WSL2-Linux-Kernel/fs/proc/proc_sysctl.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 17:07:57 +03:00
// SPDX-License-Identifier: GPL-2.0
/*
* /proc/sys support
*/
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/printk.h>
#include <linux/security.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/module.h>
#include "internal.h"
static const struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
static const struct inode_operations proc_sys_inode_operations;
static const struct file_operations proc_sys_dir_file_operations;
static const struct inode_operations proc_sys_dir_operations;
/* Support for permanently empty directories */
struct ctl_table sysctl_mount_point[] = {
{ }
};
static bool is_empty_dir(struct ctl_table_header *head)
{
return head->ctl_table[0].child == sysctl_mount_point;
}
static void set_empty_dir(struct ctl_dir *dir)
{
dir->header.ctl_table[0].child = sysctl_mount_point;
}
static void clear_empty_dir(struct ctl_dir *dir)
{
dir->header.ctl_table[0].child = NULL;
}
void proc_sys_poll_notify(struct ctl_table_poll *poll)
{
if (!poll)
return;
atomic_inc(&poll->event);
wake_up_interruptible(&poll->wait);
}
static struct ctl_table root_table[] = {
{
.procname = "",
.mode = S_IFDIR|S_IRUGO|S_IXUGO,
},
{ }
};
static struct ctl_table_root sysctl_table_root = {
.default_set.dir.header = {
{{.count = 1,
.nreg = 1,
.ctl_table = root_table }},
.ctl_table_arg = root_table,
.root = &sysctl_table_root,
.set = &sysctl_table_root.default_set,
},
};
static DEFINE_SPINLOCK(sysctl_lock);
static void drop_sysctl_table(struct ctl_table_header *header);
static int sysctl_follow_link(struct ctl_table_header **phead,
struct ctl_table **pentry);
static int insert_links(struct ctl_table_header *head);
static void put_links(struct ctl_table_header *header);
static void sysctl_print_dir(struct ctl_dir *dir)
{
if (dir->header.parent)
sysctl_print_dir(dir->header.parent);
pr_cont("%s/", dir->header.ctl_table[0].procname);
}
static int namecmp(const char *name1, int len1, const char *name2, int len2)
{
int minlen;
int cmp;
minlen = len1;
if (minlen > len2)
minlen = len2;
cmp = memcmp(name1, name2, minlen);
if (cmp == 0)
cmp = len1 - len2;
return cmp;
}
/* Called under sysctl_lock */
static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_dir *dir, const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
struct rb_node *node = dir->root.rb_node;
while (node)
{
struct ctl_node *ctl_node;
const char *procname;
int cmp;
ctl_node = rb_entry(node, struct ctl_node, node);
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
procname = entry->procname;
cmp = namecmp(name, namelen, procname, strlen(procname));
if (cmp < 0)
node = node->rb_left;
else if (cmp > 0)
node = node->rb_right;
else {
*phead = head;
return entry;
}
}
return NULL;
}
static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
{
struct rb_node *node = &head->node[entry - head->ctl_table].node;
struct rb_node **p = &head->parent->root.rb_node;
struct rb_node *parent = NULL;
const char *name = entry->procname;
int namelen = strlen(name);
while (*p) {
struct ctl_table_header *parent_head;
struct ctl_table *parent_entry;
struct ctl_node *parent_node;
const char *parent_name;
int cmp;
parent = *p;
parent_node = rb_entry(parent, struct ctl_node, node);
parent_head = parent_node->header;
parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
parent_name = parent_entry->procname;
cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
if (cmp < 0)
p = &(*p)->rb_left;
else if (cmp > 0)
p = &(*p)->rb_right;
else {
pr_err("sysctl duplicate entry: ");
sysctl_print_dir(head->parent);
pr_cont("/%s\n", entry->procname);
return -EEXIST;
}
}
rb_link_node(node, parent, p);
rb_insert_color(node, &head->parent->root);
return 0;
}
static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
{
struct rb_node *node = &head->node[entry - head->ctl_table].node;
rb_erase(node, &head->parent->root);
}
static void init_header(struct ctl_table_header *head,
struct ctl_table_root *root, struct ctl_table_set *set,
struct ctl_node *node, struct ctl_table *table)
{
head->ctl_table = table;
head->ctl_table_arg = table;
head->used = 0;
head->count = 1;
head->nreg = 1;
head->unregistering = NULL;
head->root = root;
head->set = set;
head->parent = NULL;
head->node = node;
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
INIT_HLIST_HEAD(&head->inodes);
if (node) {
struct ctl_table *entry;
rbtree: empty nodes have no color Empty nodes have no color. We can make use of this property to simplify the code emitted by the RB_EMPTY_NODE and RB_CLEAR_NODE macros. Also, we can get rid of the rb_init_node function which had been introduced by commit 88d19cf37952 ("timers: Add rb_init_node() to allow for stack allocated rb nodes") to avoid some issue with the empty node's color not being initialized. I'm not sure what the RB_EMPTY_NODE checks in rb_prev() / rb_next() are doing there, though. axboe introduced them in commit 10fd48f2376d ("rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prev"). The way I see it, the 'empty node' abstraction is only used by rbtree users to flag nodes that they haven't inserted in any rbtree, so asking the predecessor or successor of such nodes doesn't make any sense. One final rb_init_node() caller was recently added in sysctl code to implement faster sysctl name lookups. This code doesn't make use of RB_EMPTY_NODE at all, and from what I could see it only called rb_init_node() under the mistaken assumption that such initialization was required before node insertion. [sfr@canb.auug.org.au: fix net/ceph/osd_client.c build] Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 03:30:32 +04:00
for (entry = table; entry->procname; entry++, node++)
node->header = head;
}
}
static void erase_header(struct ctl_table_header *head)
{
struct ctl_table *entry;
for (entry = head->ctl_table; entry->procname; entry++)
erase_entry(head, entry);
}
static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
{
struct ctl_table *entry;
int err;
/* Is this a permanently empty directory? */
if (is_empty_dir(&dir->header))
return -EROFS;
/* Am I creating a permanently empty directory? */
if (header->ctl_table == sysctl_mount_point) {
if (!RB_EMPTY_ROOT(&dir->root))
return -EINVAL;
set_empty_dir(dir);
}
dir->header.nreg++;
header->parent = dir;
err = insert_links(header);
if (err)
goto fail_links;
for (entry = header->ctl_table; entry->procname; entry++) {
err = insert_entry(header, entry);
if (err)
goto fail;
}
return 0;
fail:
erase_header(header);
put_links(header);
fail_links:
if (header->ctl_table == sysctl_mount_point)
clear_empty_dir(dir);
header->parent = NULL;
drop_sysctl_table(&dir->header);
return err;
}
/* called under sysctl_lock */
static int use_table(struct ctl_table_header *p)
{
if (unlikely(p->unregistering))
return 0;
p->used++;
return 1;
}
/* called under sysctl_lock */
static void unuse_table(struct ctl_table_header *p)
{
if (!--p->used)
if (unlikely(p->unregistering))
complete(p->unregistering);
}
static void proc_sys_prune_dcache(struct ctl_table_header *head)
{
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
struct inode *inode;
struct proc_inode *ei;
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
struct hlist_node *node;
struct super_block *sb;
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
rcu_read_lock();
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
for (;;) {
node = hlist_first_rcu(&head->inodes);
if (!node)
break;
ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
spin_lock(&sysctl_lock);
hlist_del_init_rcu(&ei->sysctl_inodes);
spin_unlock(&sysctl_lock);
inode = &ei->vfs_inode;
sb = inode->i_sb;
if (!atomic_inc_not_zero(&sb->s_active))
continue;
inode = igrab(inode);
rcu_read_unlock();
if (unlikely(!inode)) {
deactivate_super(sb);
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
rcu_read_lock();
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
continue;
}
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
d_prune_aliases(inode);
iput(inode);
deactivate_super(sb);
rcu_read_lock();
}
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
rcu_read_unlock();
}
/* called under sysctl_lock, will reacquire if has to wait */
static void start_unregistering(struct ctl_table_header *p)
{
/*
* if p->used is 0, nobody will ever touch that entry again;
* we'll eliminate all paths to it before dropping sysctl_lock
*/
if (unlikely(p->used)) {
struct completion wait;
init_completion(&wait);
p->unregistering = &wait;
spin_unlock(&sysctl_lock);
wait_for_completion(&wait);
} else {
/* anything non-NULL; we'll never dereference it */
p->unregistering = ERR_PTR(-EINVAL);
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
spin_unlock(&sysctl_lock);
}
/*
* Prune dentries for unregistered sysctls: namespaced sysctls
* can have duplicate names and contaminate dcache very badly.
*/
proc_sys_prune_dcache(p);
/*
* do not remove from the list until nobody holds it; walking the
* list in do_sysctl() relies on that.
*/
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
spin_lock(&sysctl_lock);
erase_header(p);
}
static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
{
BUG_ON(!head);
spin_lock(&sysctl_lock);
if (!use_table(head))
head = ERR_PTR(-ENOENT);
spin_unlock(&sysctl_lock);
return head;
}
static void sysctl_head_finish(struct ctl_table_header *head)
{
if (!head)
return;
spin_lock(&sysctl_lock);
unuse_table(head);
spin_unlock(&sysctl_lock);
}
static struct ctl_table_set *
lookup_header_set(struct ctl_table_root *root)
{
struct ctl_table_set *set = &root->default_set;
if (root->lookup)
set = root->lookup(root);
return set;
}
static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
spin_lock(&sysctl_lock);
entry = find_entry(&head, dir, name, namelen);
if (entry && use_table(head))
*phead = head;
else
entry = NULL;
spin_unlock(&sysctl_lock);
return entry;
}
static struct ctl_node *first_usable_entry(struct rb_node *node)
{
struct ctl_node *ctl_node;
for (;node; node = rb_next(node)) {
ctl_node = rb_entry(node, struct ctl_node, node);
if (use_table(ctl_node->header))
return ctl_node;
}
return NULL;
}
static void first_entry(struct ctl_dir *dir,
struct ctl_table_header **phead, struct ctl_table **pentry)
{
struct ctl_table_header *head = NULL;
struct ctl_table *entry = NULL;
struct ctl_node *ctl_node;
spin_lock(&sysctl_lock);
ctl_node = first_usable_entry(rb_first(&dir->root));
spin_unlock(&sysctl_lock);
if (ctl_node) {
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
}
*phead = head;
*pentry = entry;
}
static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
{
struct ctl_table_header *head = *phead;
struct ctl_table *entry = *pentry;
struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
spin_lock(&sysctl_lock);
unuse_table(head);
ctl_node = first_usable_entry(rb_next(&ctl_node->node));
spin_unlock(&sysctl_lock);
head = NULL;
if (ctl_node) {
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
}
*phead = head;
*pentry = entry;
}
/*
* sysctl_perm does NOT grant the superuser all rights automatically, because
* some sysctl variables are readonly even to root.
*/
static int test_perm(int mode, int op)
{
if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
mode >>= 6;
else if (in_egroup_p(GLOBAL_ROOT_GID))
mode >>= 3;
if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
return 0;
return -EACCES;
}
static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
{
struct ctl_table_root *root = head->root;
int mode;
if (root->permissions)
mode = root->permissions(head, table);
else
mode = table->mode;
return test_perm(mode, op);
}
static struct inode *proc_sys_make_inode(struct super_block *sb,
struct ctl_table_header *head, struct ctl_table *table)
{
struct ctl_table_root *root = head->root;
struct inode *inode;
struct proc_inode *ei;
inode = new_inode(sb);
if (!inode)
goto out;
inode->i_ino = get_next_ino();
ei = PROC_I(inode);
spin_lock(&sysctl_lock);
proc/sysctl: Don't grab i_lock under sysctl_lock. Konstantin Khlebnikov <khlebnikov@yandex-team.ru> writes: > This patch has locking problem. I've got lockdep splat under LTP. > > [ 6633.115456] ====================================================== > [ 6633.115502] [ INFO: possible circular locking dependency detected ] > [ 6633.115553] 4.9.10-debug+ #9 Tainted: G L > [ 6633.115584] ------------------------------------------------------- > [ 6633.115627] ksm02/284980 is trying to acquire lock: > [ 6633.115659] (&sb->s_type->i_lock_key#4){+.+...}, at: [<ffffffff816bc1ce>] igrab+0x1e/0x80 > [ 6633.115834] but task is already holding lock: > [ 6633.115882] (sysctl_lock){+.+...}, at: [<ffffffff817e379b>] unregister_sysctl_table+0x6b/0x110 > [ 6633.116026] which lock already depends on the new lock. > [ 6633.116026] > [ 6633.116080] > [ 6633.116080] the existing dependency chain (in reverse order) is: > [ 6633.116117] > -> #2 (sysctl_lock){+.+...}: > -> #1 (&(&dentry->d_lockref.lock)->rlock){+.+...}: > -> #0 (&sb->s_type->i_lock_key#4){+.+...}: > > d_lock nests inside i_lock > sysctl_lock nests inside d_lock in d_compare > > This patch adds i_lock nesting inside sysctl_lock. Al Viro <viro@ZenIV.linux.org.uk> replied: > Once ->unregistering is set, you can drop sysctl_lock just fine. So I'd > try something like this - use rcu_read_lock() in proc_sys_prune_dcache(), > drop sysctl_lock() before it and regain after. Make sure that no inodes > are added to the list ones ->unregistering has been set and use RCU list > primitives for modifying the inode list, with sysctl_lock still used to > serialize its modifications. > > Freeing struct inode is RCU-delayed (see proc_destroy_inode()), so doing > igrab() is safe there. Since we don't drop inode reference until after we'd > passed beyond it in the list, list_for_each_entry_rcu() should be fine. I agree with Al Viro's analsysis of the situtation. Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Tested-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-20 08:17:03 +03:00
if (unlikely(head->unregistering)) {
spin_unlock(&sysctl_lock);
iput(inode);
inode = NULL;
goto out;
}
ei->sysctl = head;
ei->sysctl_entry = table;
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
head->count++;
spin_unlock(&sysctl_lock);
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_mode = table->mode;
if (!S_ISDIR(table->mode)) {
inode->i_mode |= S_IFREG;
inode->i_op = &proc_sys_inode_operations;
inode->i_fop = &proc_sys_file_operations;
} else {
inode->i_mode |= S_IFDIR;
inode->i_op = &proc_sys_dir_operations;
inode->i_fop = &proc_sys_dir_file_operations;
if (is_empty_dir(head))
make_empty_dir_inode(inode);
}
if (root->set_ownership)
root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
out:
return inode;
}
void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
{
spin_lock(&sysctl_lock);
proc: Fix proc_sys_prune_dcache to hold a sb reference Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes: d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-06 16:41:06 +03:00
hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
if (!--head->count)
kfree_rcu(head, rcu);
spin_unlock(&sysctl_lock);
}
static struct ctl_table_header *grab_header(struct inode *inode)
{
struct ctl_table_header *head = PROC_I(inode)->sysctl;
if (!head)
head = &sysctl_table_root.default_set.dir.header;
return sysctl_head_grab(head);
}
static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ctl_table_header *head = grab_header(dir);
struct ctl_table_header *h = NULL;
const struct qstr *name = &dentry->d_name;
struct ctl_table *p;
struct inode *inode;
struct dentry *err = ERR_PTR(-ENOENT);
struct ctl_dir *ctl_dir;
int ret;
if (IS_ERR(head))
return ERR_CAST(head);
ctl_dir = container_of(head, struct ctl_dir, header);
p = lookup_entry(&h, ctl_dir, name->name, name->len);
if (!p)
goto out;
if (S_ISLNK(p->mode)) {
ret = sysctl_follow_link(&h, &p);
err = ERR_PTR(ret);
if (ret)
goto out;
}
err = ERR_PTR(-ENOMEM);
inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
if (!inode)
goto out;
err = NULL;
d_set_d_op(dentry, &proc_sys_dentry_operations);
d_add(dentry, inode);
out:
if (h)
sysctl_head_finish(h);
sysctl_head_finish(head);
return err;
}
sysctl: merge equal proc_sys_read and proc_sys_write Many (most of) sysctls do not have a per-container sense. E.g. kernel.print_fatal_signals, vm.panic_on_oom, net.core.netdev_budget and so on and so forth. Besides, tuning then from inside a container is not even secure. On the other hand, hiding them completely from the container's tasks sometimes causes user-space to stop working. When developing net sysctl, the common practice was to duplicate a table and drop the write bits in table->mode, but this approach was not very elegant, lead to excessive memory consumption and was not suitable in general. Here's the alternative solution. To facilitate the per-container sysctls ctl_table_root-s were introduced. Each root contains a list of ctl_table_header-s that are visible to different namespaces. The idea of this set is to add the permissions() callback on the ctl_table_root to allow ctl root limit permissions to the same ctl_table-s. The main user of this functionality is the net-namespaces code, but later this will (should) be used by more and more namespaces, containers and control groups. Actually, this idea's core is in a single hunk in the third patch. First two patches are cleanups for sysctl code, while the third one mostly extends the arguments set of some sysctl functions. This patch: These ->read and ->write callbacks act in a very similar way, so merge these paths to reduce the number of places to patch later and shrink the .text size (a bit). Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Cc: Denis V. Lunev <den@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:02:40 +04:00
static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
size_t count, loff_t *ppos, int write)
{
struct inode *inode = file_inode(filp);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
ssize_t error;
size_t res;
if (IS_ERR(head))
return PTR_ERR(head);
/*
* At this point we know that the sysctl was not unregistered
* and won't be until we finish.
*/
error = -EPERM;
if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
goto out;
/* if that can happen at all, it should be -EINVAL, not -EISDIR */
error = -EINVAL;
if (!table->proc_handler)
goto out;
/* careful: calling conventions are nasty here */
res = count;
error = table->proc_handler(table, write, buf, &res, ppos);
if (!error)
error = res;
out:
sysctl_head_finish(head);
return error;
}
sysctl: merge equal proc_sys_read and proc_sys_write Many (most of) sysctls do not have a per-container sense. E.g. kernel.print_fatal_signals, vm.panic_on_oom, net.core.netdev_budget and so on and so forth. Besides, tuning then from inside a container is not even secure. On the other hand, hiding them completely from the container's tasks sometimes causes user-space to stop working. When developing net sysctl, the common practice was to duplicate a table and drop the write bits in table->mode, but this approach was not very elegant, lead to excessive memory consumption and was not suitable in general. Here's the alternative solution. To facilitate the per-container sysctls ctl_table_root-s were introduced. Each root contains a list of ctl_table_header-s that are visible to different namespaces. The idea of this set is to add the permissions() callback on the ctl_table_root to allow ctl root limit permissions to the same ctl_table-s. The main user of this functionality is the net-namespaces code, but later this will (should) be used by more and more namespaces, containers and control groups. Actually, this idea's core is in a single hunk in the third patch. First two patches are cleanups for sysctl code, while the third one mostly extends the arguments set of some sysctl functions. This patch: These ->read and ->write callbacks act in a very similar way, so merge these paths to reduce the number of places to patch later and shrink the .text size (a bit). Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Cc: Denis V. Lunev <den@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:02:40 +04:00
static ssize_t proc_sys_read(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
sysctl: merge equal proc_sys_read and proc_sys_write Many (most of) sysctls do not have a per-container sense. E.g. kernel.print_fatal_signals, vm.panic_on_oom, net.core.netdev_budget and so on and so forth. Besides, tuning then from inside a container is not even secure. On the other hand, hiding them completely from the container's tasks sometimes causes user-space to stop working. When developing net sysctl, the common practice was to duplicate a table and drop the write bits in table->mode, but this approach was not very elegant, lead to excessive memory consumption and was not suitable in general. Here's the alternative solution. To facilitate the per-container sysctls ctl_table_root-s were introduced. Each root contains a list of ctl_table_header-s that are visible to different namespaces. The idea of this set is to add the permissions() callback on the ctl_table_root to allow ctl root limit permissions to the same ctl_table-s. The main user of this functionality is the net-namespaces code, but later this will (should) be used by more and more namespaces, containers and control groups. Actually, this idea's core is in a single hunk in the third patch. First two patches are cleanups for sysctl code, while the third one mostly extends the arguments set of some sysctl functions. This patch: These ->read and ->write callbacks act in a very similar way, so merge these paths to reduce the number of places to patch later and shrink the .text size (a bit). Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Cc: Denis V. Lunev <den@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:02:40 +04:00
return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
}
sysctl: merge equal proc_sys_read and proc_sys_write Many (most of) sysctls do not have a per-container sense. E.g. kernel.print_fatal_signals, vm.panic_on_oom, net.core.netdev_budget and so on and so forth. Besides, tuning then from inside a container is not even secure. On the other hand, hiding them completely from the container's tasks sometimes causes user-space to stop working. When developing net sysctl, the common practice was to duplicate a table and drop the write bits in table->mode, but this approach was not very elegant, lead to excessive memory consumption and was not suitable in general. Here's the alternative solution. To facilitate the per-container sysctls ctl_table_root-s were introduced. Each root contains a list of ctl_table_header-s that are visible to different namespaces. The idea of this set is to add the permissions() callback on the ctl_table_root to allow ctl root limit permissions to the same ctl_table-s. The main user of this functionality is the net-namespaces code, but later this will (should) be used by more and more namespaces, containers and control groups. Actually, this idea's core is in a single hunk in the third patch. First two patches are cleanups for sysctl code, while the third one mostly extends the arguments set of some sysctl functions. This patch: These ->read and ->write callbacks act in a very similar way, so merge these paths to reduce the number of places to patch later and shrink the .text size (a bit). Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Cc: Denis V. Lunev <den@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:02:40 +04:00
static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
size_t count, loff_t *ppos)
{
return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
}
static int proc_sys_open(struct inode *inode, struct file *filp)
{
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
/* sysctl was unregistered */
if (IS_ERR(head))
return PTR_ERR(head);
if (table->poll)
filp->private_data = proc_sys_poll_event(table->poll);
sysctl_head_finish(head);
return 0;
}
static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
{
struct inode *inode = file_inode(filp);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
unsigned int ret = DEFAULT_POLLMASK;
unsigned long event;
/* sysctl was unregistered */
if (IS_ERR(head))
return POLLERR | POLLHUP;
if (!table->proc_handler)
goto out;
if (!table->poll)
goto out;
event = (unsigned long)filp->private_data;
poll_wait(filp, &table->poll->wait, wait);
if (event != atomic_read(&table->poll->event)) {
filp->private_data = proc_sys_poll_event(table->poll);
ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
}
out:
sysctl_head_finish(head);
return ret;
}
static bool proc_sys_fill_cache(struct file *file,
struct dir_context *ctx,
struct ctl_table_header *head,
struct ctl_table *table)
{
struct dentry *child, *dir = file->f_path.dentry;
struct inode *inode;
struct qstr qname;
ino_t ino = 0;
unsigned type = DT_UNKNOWN;
qname.name = table->procname;
qname.len = strlen(table->procname);
qname.hash = full_name_hash(dir, qname.name, qname.len);
child = d_lookup(dir, &qname);
if (!child) {
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
child = d_alloc_parallel(dir, &qname, &wq);
if (IS_ERR(child))
return false;
if (d_in_lookup(child)) {
inode = proc_sys_make_inode(dir->d_sb, head, table);
if (!inode) {
d_lookup_done(child);
dput(child);
return false;
}
d_set_d_op(child, &proc_sys_dentry_operations);
d_add(child, inode);
}
}
inode = d_inode(child);
ino = inode->i_ino;
type = inode->i_mode >> 12;
dput(child);
return dir_emit(ctx, qname.name, qname.len, ino, type);
}
static bool proc_sys_link_fill_cache(struct file *file,
struct dir_context *ctx,
struct ctl_table_header *head,
struct ctl_table *table)
{
bool ret = true;
head = sysctl_head_grab(head);
if (S_ISLNK(table->mode)) {
/* It is not an error if we can not follow the link ignore it */
int err = sysctl_follow_link(&head, &table);
if (err)
goto out;
}
ret = proc_sys_fill_cache(file, ctx, head, table);
out:
sysctl_head_finish(head);
return ret;
}
static int scan(struct ctl_table_header *head, struct ctl_table *table,
unsigned long *pos, struct file *file,
struct dir_context *ctx)
{
bool res;
if ((*pos)++ < ctx->pos)
return true;
if (unlikely(S_ISLNK(table->mode)))
res = proc_sys_link_fill_cache(file, ctx, head, table);
else
res = proc_sys_fill_cache(file, ctx, head, table);
if (res)
ctx->pos = *pos;
return res;
}
static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
{
struct ctl_table_header *head = grab_header(file_inode(file));
struct ctl_table_header *h = NULL;
struct ctl_table *entry;
struct ctl_dir *ctl_dir;
unsigned long pos;
if (IS_ERR(head))
return PTR_ERR(head);
ctl_dir = container_of(head, struct ctl_dir, header);
if (!dir_emit_dots(file, ctx))
sysctl: Drop reference added by grab_header in proc_sys_readdir Fixes CVE-2016-9191, proc_sys_readdir doesn't drop reference added by grab_header when return from !dir_emit_dots path. It can cause any path called unregister_sysctl_table will wait forever. The calltrace of CVE-2016-9191: [ 5535.960522] Call Trace: [ 5535.963265] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5535.968817] [<ffffffff817d33fb>] schedule_timeout+0x3db/0x6f0 [ 5535.975346] [<ffffffff817cf055>] ? wait_for_completion+0x45/0x130 [ 5535.982256] [<ffffffff817cf0d3>] wait_for_completion+0xc3/0x130 [ 5535.988972] [<ffffffff810d1fd0>] ? wake_up_q+0x80/0x80 [ 5535.994804] [<ffffffff8130de64>] drop_sysctl_table+0xc4/0xe0 [ 5536.001227] [<ffffffff8130de17>] drop_sysctl_table+0x77/0xe0 [ 5536.007648] [<ffffffff8130decd>] unregister_sysctl_table+0x4d/0xa0 [ 5536.014654] [<ffffffff8130deff>] unregister_sysctl_table+0x7f/0xa0 [ 5536.021657] [<ffffffff810f57f5>] unregister_sched_domain_sysctl+0x15/0x40 [ 5536.029344] [<ffffffff810d7704>] partition_sched_domains+0x44/0x450 [ 5536.036447] [<ffffffff817d0761>] ? __mutex_unlock_slowpath+0x111/0x1f0 [ 5536.043844] [<ffffffff81167684>] rebuild_sched_domains_locked+0x64/0xb0 [ 5536.051336] [<ffffffff8116789d>] update_flag+0x11d/0x210 [ 5536.057373] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.064186] [<ffffffff81167acb>] ? cpuset_css_offline+0x1b/0x60 [ 5536.070899] [<ffffffff810fce3d>] ? trace_hardirqs_on+0xd/0x10 [ 5536.077420] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.084234] [<ffffffff8115a9f5>] ? css_killed_work_fn+0x25/0x220 [ 5536.091049] [<ffffffff81167ae5>] cpuset_css_offline+0x35/0x60 [ 5536.097571] [<ffffffff8115aa2c>] css_killed_work_fn+0x5c/0x220 [ 5536.104207] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5536.110736] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5536.117461] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5536.123697] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5536.130426] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5536.135991] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5536.142041] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 One cgroup maintainer mentioned that "cgroup is trying to offline a cpuset css, which takes place under cgroup_mutex. The offlining ends up trying to drain active usages of a sysctl table which apprently is not happening." The real reason is that proc_sys_readdir doesn't drop reference added by grab_header when return from !dir_emit_dots path. So this cpuset offline path will wait here forever. See here for details: http://www.openwall.com/lists/oss-security/2016/11/04/13 Fixes: f0c3b5093add ("[readdir] convert procfs") Cc: stable@vger.kernel.org Reported-by: CAI Qian <caiqian@redhat.com> Tested-by: Yang Shukui <yangshukui@huawei.com> Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-06 04:32:32 +03:00
goto out;
pos = 2;
for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
if (!scan(h, entry, &pos, file, ctx)) {
sysctl_head_finish(h);
break;
}
}
sysctl: Drop reference added by grab_header in proc_sys_readdir Fixes CVE-2016-9191, proc_sys_readdir doesn't drop reference added by grab_header when return from !dir_emit_dots path. It can cause any path called unregister_sysctl_table will wait forever. The calltrace of CVE-2016-9191: [ 5535.960522] Call Trace: [ 5535.963265] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5535.968817] [<ffffffff817d33fb>] schedule_timeout+0x3db/0x6f0 [ 5535.975346] [<ffffffff817cf055>] ? wait_for_completion+0x45/0x130 [ 5535.982256] [<ffffffff817cf0d3>] wait_for_completion+0xc3/0x130 [ 5535.988972] [<ffffffff810d1fd0>] ? wake_up_q+0x80/0x80 [ 5535.994804] [<ffffffff8130de64>] drop_sysctl_table+0xc4/0xe0 [ 5536.001227] [<ffffffff8130de17>] drop_sysctl_table+0x77/0xe0 [ 5536.007648] [<ffffffff8130decd>] unregister_sysctl_table+0x4d/0xa0 [ 5536.014654] [<ffffffff8130deff>] unregister_sysctl_table+0x7f/0xa0 [ 5536.021657] [<ffffffff810f57f5>] unregister_sched_domain_sysctl+0x15/0x40 [ 5536.029344] [<ffffffff810d7704>] partition_sched_domains+0x44/0x450 [ 5536.036447] [<ffffffff817d0761>] ? __mutex_unlock_slowpath+0x111/0x1f0 [ 5536.043844] [<ffffffff81167684>] rebuild_sched_domains_locked+0x64/0xb0 [ 5536.051336] [<ffffffff8116789d>] update_flag+0x11d/0x210 [ 5536.057373] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.064186] [<ffffffff81167acb>] ? cpuset_css_offline+0x1b/0x60 [ 5536.070899] [<ffffffff810fce3d>] ? trace_hardirqs_on+0xd/0x10 [ 5536.077420] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.084234] [<ffffffff8115a9f5>] ? css_killed_work_fn+0x25/0x220 [ 5536.091049] [<ffffffff81167ae5>] cpuset_css_offline+0x35/0x60 [ 5536.097571] [<ffffffff8115aa2c>] css_killed_work_fn+0x5c/0x220 [ 5536.104207] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5536.110736] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5536.117461] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5536.123697] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5536.130426] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5536.135991] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5536.142041] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 One cgroup maintainer mentioned that "cgroup is trying to offline a cpuset css, which takes place under cgroup_mutex. The offlining ends up trying to drain active usages of a sysctl table which apprently is not happening." The real reason is that proc_sys_readdir doesn't drop reference added by grab_header when return from !dir_emit_dots path. So this cpuset offline path will wait here forever. See here for details: http://www.openwall.com/lists/oss-security/2016/11/04/13 Fixes: f0c3b5093add ("[readdir] convert procfs") Cc: stable@vger.kernel.org Reported-by: CAI Qian <caiqian@redhat.com> Tested-by: Yang Shukui <yangshukui@huawei.com> Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-06 04:32:32 +03:00
out:
sysctl_head_finish(head);
return 0;
}
static int proc_sys_permission(struct inode *inode, int mask)
{
/*
* sysctl entries that are not writeable,
* are _NOT_ writeable, capabilities or not.
*/
struct ctl_table_header *head;
struct ctl_table *table;
int error;
/* Executable files are not allowed under /proc/sys/ */
if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
return -EACCES;
head = grab_header(inode);
if (IS_ERR(head))
return PTR_ERR(head);
table = PROC_I(inode)->sysctl_entry;
if (!table) /* global root - r-xr-xr-x */
error = mask & MAY_WRITE ? -EACCES : 0;
else /* Use the permissions on the sysctl table entry */
error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
sysctl_head_finish(head);
return error;
}
static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
int error;
if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
return -EPERM;
error = setattr_prepare(dentry, attr);
if (error)
return error;
setattr_copy(inode, attr);
mark_inode_dirty(inode);
return 0;
}
statx: Add a system call to make enhanced file info available Add a system call to make extended file information available, including file creation and some attribute flags where available through the underlying filesystem. The getattr inode operation is altered to take two additional arguments: a u32 request_mask and an unsigned int flags that indicate the synchronisation mode. This change is propagated to the vfs_getattr*() function. Functions like vfs_stat() are now inline wrappers around new functions vfs_statx() and vfs_statx_fd() to reduce stack usage. ======== OVERVIEW ======== The idea was initially proposed as a set of xattrs that could be retrieved with getxattr(), but the general preference proved to be for a new syscall with an extended stat structure. A number of requests were gathered for features to be included. The following have been included: (1) Make the fields a consistent size on all arches and make them large. (2) Spare space, request flags and information flags are provided for future expansion. (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an __s64). (4) Creation time: The SMB protocol carries the creation time, which could be exported by Samba, which will in turn help CIFS make use of FS-Cache as that can be used for coherency data (stx_btime). This is also specified in NFSv4 as a recommended attribute and could be exported by NFSD [Steve French]. (5) Lightweight stat: Ask for just those details of interest, and allow a netfs (such as NFS) to approximate anything not of interest, possibly without going to the server [Trond Myklebust, Ulrich Drepper, Andreas Dilger] (AT_STATX_DONT_SYNC). (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks its cached attributes are up to date [Trond Myklebust] (AT_STATX_FORCE_SYNC). And the following have been left out for future extension: (7) Data version number: Could be used by userspace NFS servers [Aneesh Kumar]. Can also be used to modify fill_post_wcc() in NFSD which retrieves i_version directly, but has just called vfs_getattr(). It could get it from the kstat struct if it used vfs_xgetattr() instead. (There's disagreement on the exact semantics of a single field, since not all filesystems do this the same way). (8) BSD stat compatibility: Including more fields from the BSD stat such as creation time (st_btime) and inode generation number (st_gen) [Jeremy Allison, Bernd Schubert]. (9) Inode generation number: Useful for FUSE and userspace NFS servers [Bernd Schubert]. (This was asked for but later deemed unnecessary with the open-by-handle capability available and caused disagreement as to whether it's a security hole or not). (10) Extra coherency data may be useful in making backups [Andreas Dilger]. (No particular data were offered, but things like last backup timestamp, the data version number and the DOS archive bit would come into this category). (11) Allow the filesystem to indicate what it can/cannot provide: A filesystem can now say it doesn't support a standard stat feature if that isn't available, so if, for instance, inode numbers or UIDs don't exist or are fabricated locally... (This requires a separate system call - I have an fsinfo() call idea for this). (12) Store a 16-byte volume ID in the superblock that can be returned in struct xstat [Steve French]. (Deferred to fsinfo). (13) Include granularity fields in the time data to indicate the granularity of each of the times (NFSv4 time_delta) [Steve French]. (Deferred to fsinfo). (14) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. Note that the Linux IOC flags are a mess and filesystems such as Ext4 define flags that aren't in linux/fs.h, so translation in the kernel may be a necessity (or, possibly, we provide the filesystem type too). (Some attributes are made available in stx_attributes, but the general feeling was that the IOC flags were to ext[234]-specific and shouldn't be exposed through statx this way). (15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer, Michael Kerrisk]. (Deferred, probably to fsinfo. Finding out if there's an ACL or seclabal might require extra filesystem operations). (16) Femtosecond-resolution timestamps [Dave Chinner]. (A __reserved field has been left in the statx_timestamp struct for this - if there proves to be a need). (17) A set multiple attributes syscall to go with this. =============== NEW SYSTEM CALL =============== The new system call is: int ret = statx(int dfd, const char *filename, unsigned int flags, unsigned int mask, struct statx *buffer); The dfd, filename and flags parameters indicate the file to query, in a similar way to fstatat(). There is no equivalent of lstat() as that can be emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as that can be emulated by passing a NULL filename to statx() with the fd of interest in dfd. Whether or not statx() synchronises the attributes with the backing store can be controlled by OR'ing a value into the flags argument (this typically only affects network filesystems): (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this respect. (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise its attributes with the server - which might require data writeback to occur to get the timestamps correct. (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a network filesystem. The resulting values should be considered approximate. mask is a bitmask indicating the fields in struct statx that are of interest to the caller. The user should set this to STATX_BASIC_STATS to get the basic set returned by stat(). It should be noted that asking for more information may entail extra I/O operations. buffer points to the destination for the data. This must be 256 bytes in size. ====================== MAIN ATTRIBUTES RECORD ====================== The following structures are defined in which to return the main attribute set: struct statx_timestamp { __s64 tv_sec; __s32 tv_nsec; __s32 __reserved; }; struct statx { __u32 stx_mask; __u32 stx_blksize; __u64 stx_attributes; __u32 stx_nlink; __u32 stx_uid; __u32 stx_gid; __u16 stx_mode; __u16 __spare0[1]; __u64 stx_ino; __u64 stx_size; __u64 stx_blocks; __u64 __spare1[1]; struct statx_timestamp stx_atime; struct statx_timestamp stx_btime; struct statx_timestamp stx_ctime; struct statx_timestamp stx_mtime; __u32 stx_rdev_major; __u32 stx_rdev_minor; __u32 stx_dev_major; __u32 stx_dev_minor; __u64 __spare2[14]; }; The defined bits in request_mask and stx_mask are: STATX_TYPE Want/got stx_mode & S_IFMT STATX_MODE Want/got stx_mode & ~S_IFMT STATX_NLINK Want/got stx_nlink STATX_UID Want/got stx_uid STATX_GID Want/got stx_gid STATX_ATIME Want/got stx_atime{,_ns} STATX_MTIME Want/got stx_mtime{,_ns} STATX_CTIME Want/got stx_ctime{,_ns} STATX_INO Want/got stx_ino STATX_SIZE Want/got stx_size STATX_BLOCKS Want/got stx_blocks STATX_BASIC_STATS [The stuff in the normal stat struct] STATX_BTIME Want/got stx_btime{,_ns} STATX_ALL [All currently available stuff] stx_btime is the file creation time, stx_mask is a bitmask indicating the data provided and __spares*[] are where as-yet undefined fields can be placed. Time fields are structures with separate seconds and nanoseconds fields plus a reserved field in case we want to add even finer resolution. Note that times will be negative if before 1970; in such a case, the nanosecond fields will also be negative if not zero. The bits defined in the stx_attributes field convey information about a file, how it is accessed, where it is and what it does. The following attributes map to FS_*_FL flags and are the same numerical value: STATX_ATTR_COMPRESSED File is compressed by the fs STATX_ATTR_IMMUTABLE File is marked immutable STATX_ATTR_APPEND File is append-only STATX_ATTR_NODUMP File is not to be dumped STATX_ATTR_ENCRYPTED File requires key to decrypt in fs Within the kernel, the supported flags are listed by: KSTAT_ATTR_FS_IOC_FLAGS [Are any other IOC flags of sufficient general interest to be exposed through this interface?] New flags include: STATX_ATTR_AUTOMOUNT Object is an automount trigger These are for the use of GUI tools that might want to mark files specially, depending on what they are. Fields in struct statx come in a number of classes: (0) stx_dev_*, stx_blksize. These are local system information and are always available. (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino, stx_size, stx_blocks. These will be returned whether the caller asks for them or not. The corresponding bits in stx_mask will be set to indicate whether they actually have valid values. If the caller didn't ask for them, then they may be approximated. For example, NFS won't waste any time updating them from the server, unless as a byproduct of updating something requested. If the values don't actually exist for the underlying object (such as UID or GID on a DOS file), then the bit won't be set in the stx_mask, even if the caller asked for the value. In such a case, the returned value will be a fabrication. Note that there are instances where the type might not be valid, for instance Windows reparse points. (2) stx_rdev_*. This will be set only if stx_mode indicates we're looking at a blockdev or a chardev, otherwise will be 0. (3) stx_btime. Similar to (1), except this will be set to 0 if it doesn't exist. ======= TESTING ======= The following test program can be used to test the statx system call: samples/statx/test-statx.c Just compile and run, passing it paths to the files you want to examine. The file is built automatically if CONFIG_SAMPLES is enabled. Here's some example output. Firstly, an NFS directory that crosses to another FSID. Note that the AUTOMOUNT attribute is set because transiting this directory will cause d_automount to be invoked by the VFS. [root@andromeda ~]# /tmp/test-statx -A /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:26 Inode: 1703937 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------) Secondly, the result of automounting on that directory. [root@andromeda ~]# /tmp/test-statx /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:27 Inode: 2 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-31 19:46:22 +03:00
static int proc_sys_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
statx: Add a system call to make enhanced file info available Add a system call to make extended file information available, including file creation and some attribute flags where available through the underlying filesystem. The getattr inode operation is altered to take two additional arguments: a u32 request_mask and an unsigned int flags that indicate the synchronisation mode. This change is propagated to the vfs_getattr*() function. Functions like vfs_stat() are now inline wrappers around new functions vfs_statx() and vfs_statx_fd() to reduce stack usage. ======== OVERVIEW ======== The idea was initially proposed as a set of xattrs that could be retrieved with getxattr(), but the general preference proved to be for a new syscall with an extended stat structure. A number of requests were gathered for features to be included. The following have been included: (1) Make the fields a consistent size on all arches and make them large. (2) Spare space, request flags and information flags are provided for future expansion. (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an __s64). (4) Creation time: The SMB protocol carries the creation time, which could be exported by Samba, which will in turn help CIFS make use of FS-Cache as that can be used for coherency data (stx_btime). This is also specified in NFSv4 as a recommended attribute and could be exported by NFSD [Steve French]. (5) Lightweight stat: Ask for just those details of interest, and allow a netfs (such as NFS) to approximate anything not of interest, possibly without going to the server [Trond Myklebust, Ulrich Drepper, Andreas Dilger] (AT_STATX_DONT_SYNC). (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks its cached attributes are up to date [Trond Myklebust] (AT_STATX_FORCE_SYNC). And the following have been left out for future extension: (7) Data version number: Could be used by userspace NFS servers [Aneesh Kumar]. Can also be used to modify fill_post_wcc() in NFSD which retrieves i_version directly, but has just called vfs_getattr(). It could get it from the kstat struct if it used vfs_xgetattr() instead. (There's disagreement on the exact semantics of a single field, since not all filesystems do this the same way). (8) BSD stat compatibility: Including more fields from the BSD stat such as creation time (st_btime) and inode generation number (st_gen) [Jeremy Allison, Bernd Schubert]. (9) Inode generation number: Useful for FUSE and userspace NFS servers [Bernd Schubert]. (This was asked for but later deemed unnecessary with the open-by-handle capability available and caused disagreement as to whether it's a security hole or not). (10) Extra coherency data may be useful in making backups [Andreas Dilger]. (No particular data were offered, but things like last backup timestamp, the data version number and the DOS archive bit would come into this category). (11) Allow the filesystem to indicate what it can/cannot provide: A filesystem can now say it doesn't support a standard stat feature if that isn't available, so if, for instance, inode numbers or UIDs don't exist or are fabricated locally... (This requires a separate system call - I have an fsinfo() call idea for this). (12) Store a 16-byte volume ID in the superblock that can be returned in struct xstat [Steve French]. (Deferred to fsinfo). (13) Include granularity fields in the time data to indicate the granularity of each of the times (NFSv4 time_delta) [Steve French]. (Deferred to fsinfo). (14) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. Note that the Linux IOC flags are a mess and filesystems such as Ext4 define flags that aren't in linux/fs.h, so translation in the kernel may be a necessity (or, possibly, we provide the filesystem type too). (Some attributes are made available in stx_attributes, but the general feeling was that the IOC flags were to ext[234]-specific and shouldn't be exposed through statx this way). (15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer, Michael Kerrisk]. (Deferred, probably to fsinfo. Finding out if there's an ACL or seclabal might require extra filesystem operations). (16) Femtosecond-resolution timestamps [Dave Chinner]. (A __reserved field has been left in the statx_timestamp struct for this - if there proves to be a need). (17) A set multiple attributes syscall to go with this. =============== NEW SYSTEM CALL =============== The new system call is: int ret = statx(int dfd, const char *filename, unsigned int flags, unsigned int mask, struct statx *buffer); The dfd, filename and flags parameters indicate the file to query, in a similar way to fstatat(). There is no equivalent of lstat() as that can be emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as that can be emulated by passing a NULL filename to statx() with the fd of interest in dfd. Whether or not statx() synchronises the attributes with the backing store can be controlled by OR'ing a value into the flags argument (this typically only affects network filesystems): (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this respect. (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise its attributes with the server - which might require data writeback to occur to get the timestamps correct. (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a network filesystem. The resulting values should be considered approximate. mask is a bitmask indicating the fields in struct statx that are of interest to the caller. The user should set this to STATX_BASIC_STATS to get the basic set returned by stat(). It should be noted that asking for more information may entail extra I/O operations. buffer points to the destination for the data. This must be 256 bytes in size. ====================== MAIN ATTRIBUTES RECORD ====================== The following structures are defined in which to return the main attribute set: struct statx_timestamp { __s64 tv_sec; __s32 tv_nsec; __s32 __reserved; }; struct statx { __u32 stx_mask; __u32 stx_blksize; __u64 stx_attributes; __u32 stx_nlink; __u32 stx_uid; __u32 stx_gid; __u16 stx_mode; __u16 __spare0[1]; __u64 stx_ino; __u64 stx_size; __u64 stx_blocks; __u64 __spare1[1]; struct statx_timestamp stx_atime; struct statx_timestamp stx_btime; struct statx_timestamp stx_ctime; struct statx_timestamp stx_mtime; __u32 stx_rdev_major; __u32 stx_rdev_minor; __u32 stx_dev_major; __u32 stx_dev_minor; __u64 __spare2[14]; }; The defined bits in request_mask and stx_mask are: STATX_TYPE Want/got stx_mode & S_IFMT STATX_MODE Want/got stx_mode & ~S_IFMT STATX_NLINK Want/got stx_nlink STATX_UID Want/got stx_uid STATX_GID Want/got stx_gid STATX_ATIME Want/got stx_atime{,_ns} STATX_MTIME Want/got stx_mtime{,_ns} STATX_CTIME Want/got stx_ctime{,_ns} STATX_INO Want/got stx_ino STATX_SIZE Want/got stx_size STATX_BLOCKS Want/got stx_blocks STATX_BASIC_STATS [The stuff in the normal stat struct] STATX_BTIME Want/got stx_btime{,_ns} STATX_ALL [All currently available stuff] stx_btime is the file creation time, stx_mask is a bitmask indicating the data provided and __spares*[] are where as-yet undefined fields can be placed. Time fields are structures with separate seconds and nanoseconds fields plus a reserved field in case we want to add even finer resolution. Note that times will be negative if before 1970; in such a case, the nanosecond fields will also be negative if not zero. The bits defined in the stx_attributes field convey information about a file, how it is accessed, where it is and what it does. The following attributes map to FS_*_FL flags and are the same numerical value: STATX_ATTR_COMPRESSED File is compressed by the fs STATX_ATTR_IMMUTABLE File is marked immutable STATX_ATTR_APPEND File is append-only STATX_ATTR_NODUMP File is not to be dumped STATX_ATTR_ENCRYPTED File requires key to decrypt in fs Within the kernel, the supported flags are listed by: KSTAT_ATTR_FS_IOC_FLAGS [Are any other IOC flags of sufficient general interest to be exposed through this interface?] New flags include: STATX_ATTR_AUTOMOUNT Object is an automount trigger These are for the use of GUI tools that might want to mark files specially, depending on what they are. Fields in struct statx come in a number of classes: (0) stx_dev_*, stx_blksize. These are local system information and are always available. (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino, stx_size, stx_blocks. These will be returned whether the caller asks for them or not. The corresponding bits in stx_mask will be set to indicate whether they actually have valid values. If the caller didn't ask for them, then they may be approximated. For example, NFS won't waste any time updating them from the server, unless as a byproduct of updating something requested. If the values don't actually exist for the underlying object (such as UID or GID on a DOS file), then the bit won't be set in the stx_mask, even if the caller asked for the value. In such a case, the returned value will be a fabrication. Note that there are instances where the type might not be valid, for instance Windows reparse points. (2) stx_rdev_*. This will be set only if stx_mode indicates we're looking at a blockdev or a chardev, otherwise will be 0. (3) stx_btime. Similar to (1), except this will be set to 0 if it doesn't exist. ======= TESTING ======= The following test program can be used to test the statx system call: samples/statx/test-statx.c Just compile and run, passing it paths to the files you want to examine. The file is built automatically if CONFIG_SAMPLES is enabled. Here's some example output. Firstly, an NFS directory that crosses to another FSID. Note that the AUTOMOUNT attribute is set because transiting this directory will cause d_automount to be invoked by the VFS. [root@andromeda ~]# /tmp/test-statx -A /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:26 Inode: 1703937 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------) Secondly, the result of automounting on that directory. [root@andromeda ~]# /tmp/test-statx /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:27 Inode: 2 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-31 19:46:22 +03:00
struct inode *inode = d_inode(path->dentry);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
if (IS_ERR(head))
return PTR_ERR(head);
generic_fillattr(inode, stat);
if (table)
stat->mode = (stat->mode & S_IFMT) | table->mode;
sysctl_head_finish(head);
return 0;
}
static const struct file_operations proc_sys_file_operations = {
.open = proc_sys_open,
.poll = proc_sys_poll,
.read = proc_sys_read,
.write = proc_sys_write,
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 20:52:59 +04:00
.llseek = default_llseek,
};
static const struct file_operations proc_sys_dir_file_operations = {
.read = generic_read_dir,
.iterate_shared = proc_sys_readdir,
.llseek = generic_file_llseek,
};
static const struct inode_operations proc_sys_inode_operations = {
.permission = proc_sys_permission,
.setattr = proc_sys_setattr,
.getattr = proc_sys_getattr,
};
static const struct inode_operations proc_sys_dir_operations = {
.lookup = proc_sys_lookup,
.permission = proc_sys_permission,
.setattr = proc_sys_setattr,
.getattr = proc_sys_getattr,
};
static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
{
if (flags & LOOKUP_RCU)
return -ECHILD;
return !PROC_I(d_inode(dentry))->sysctl->unregistering;
}
static int proc_sys_delete(const struct dentry *dentry)
{
return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
}
static int sysctl_is_seen(struct ctl_table_header *p)
{
struct ctl_table_set *set = p->set;
int res;
spin_lock(&sysctl_lock);
if (p->unregistering)
res = 0;
else if (!set->is_seen)
res = 1;
else
res = set->is_seen(set);
spin_unlock(&sysctl_lock);
return res;
}
static int proc_sys_compare(const struct dentry *dentry,
unsigned int len, const char *str, const struct qstr *name)
{
struct ctl_table_header *head;
struct inode *inode;
fs: rcu-walk for path lookup Perform common cases of path lookups without any stores or locking in the ancestor dentry elements. This is called rcu-walk, as opposed to the current algorithm which is a refcount based walk, or ref-walk. This results in far fewer atomic operations on every path element, significantly improving path lookup performance. It also avoids cacheline bouncing on common dentries, significantly improving scalability. The overall design is like this: * LOOKUP_RCU is set in nd->flags, which distinguishes rcu-walk from ref-walk. * Take the RCU lock for the entire path walk, starting with the acquiring of the starting path (eg. root/cwd/fd-path). So now dentry refcounts are not required for dentry persistence. * synchronize_rcu is called when unregistering a filesystem, so we can access d_ops and i_ops during rcu-walk. * Similarly take the vfsmount lock for the entire path walk. So now mnt refcounts are not required for persistence. Also we are free to perform mount lookups, and to assume dentry mount points and mount roots are stable up and down the path. * Have a per-dentry seqlock to protect the dentry name, parent, and inode, so we can load this tuple atomically, and also check whether any of its members have changed. * Dentry lookups (based on parent, candidate string tuple) recheck the parent sequence after the child is found in case anything changed in the parent during the path walk. * inode is also RCU protected so we can load d_inode and use the inode for limited things. * i_mode, i_uid, i_gid can be tested for exec permissions during path walk. * i_op can be loaded. When we reach the destination dentry, we lock it, recheck lookup sequence, and increment its refcount and mountpoint refcount. RCU and vfsmount locks are dropped. This is termed "dropping rcu-walk". If the dentry refcount does not match, we can not drop rcu-walk gracefully at the current point in the lokup, so instead return -ECHILD (for want of a better errno). This signals the path walking code to re-do the entire lookup with a ref-walk. Aside from the final dentry, there are other situations that may be encounted where we cannot continue rcu-walk. In that case, we drop rcu-walk (ie. take a reference on the last good dentry) and continue with a ref-walk. Again, if we can drop rcu-walk gracefully, we return -ECHILD and do the whole lookup using ref-walk. But it is very important that we can continue with ref-walk for most cases, particularly to avoid the overhead of double lookups, and to gain the scalability advantages on common path elements (like cwd and root). The cases where rcu-walk cannot continue are: * NULL dentry (ie. any uncached path element) * parent with d_inode->i_op->permission or ACLs * dentries with d_revalidate * Following links In future patches, permission checks and d_revalidate become rcu-walk aware. It may be possible eventually to make following links rcu-walk aware. Uncached path elements will always require dropping to ref-walk mode, at the very least because i_mutex needs to be grabbed, and objects allocated. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 09:49:52 +03:00
/* Although proc doesn't have negative dentries, rcu-walk means
* that inode here can be NULL */
/* AV: can it, indeed? */
inode = d_inode_rcu(dentry);
fs: rcu-walk for path lookup Perform common cases of path lookups without any stores or locking in the ancestor dentry elements. This is called rcu-walk, as opposed to the current algorithm which is a refcount based walk, or ref-walk. This results in far fewer atomic operations on every path element, significantly improving path lookup performance. It also avoids cacheline bouncing on common dentries, significantly improving scalability. The overall design is like this: * LOOKUP_RCU is set in nd->flags, which distinguishes rcu-walk from ref-walk. * Take the RCU lock for the entire path walk, starting with the acquiring of the starting path (eg. root/cwd/fd-path). So now dentry refcounts are not required for dentry persistence. * synchronize_rcu is called when unregistering a filesystem, so we can access d_ops and i_ops during rcu-walk. * Similarly take the vfsmount lock for the entire path walk. So now mnt refcounts are not required for persistence. Also we are free to perform mount lookups, and to assume dentry mount points and mount roots are stable up and down the path. * Have a per-dentry seqlock to protect the dentry name, parent, and inode, so we can load this tuple atomically, and also check whether any of its members have changed. * Dentry lookups (based on parent, candidate string tuple) recheck the parent sequence after the child is found in case anything changed in the parent during the path walk. * inode is also RCU protected so we can load d_inode and use the inode for limited things. * i_mode, i_uid, i_gid can be tested for exec permissions during path walk. * i_op can be loaded. When we reach the destination dentry, we lock it, recheck lookup sequence, and increment its refcount and mountpoint refcount. RCU and vfsmount locks are dropped. This is termed "dropping rcu-walk". If the dentry refcount does not match, we can not drop rcu-walk gracefully at the current point in the lokup, so instead return -ECHILD (for want of a better errno). This signals the path walking code to re-do the entire lookup with a ref-walk. Aside from the final dentry, there are other situations that may be encounted where we cannot continue rcu-walk. In that case, we drop rcu-walk (ie. take a reference on the last good dentry) and continue with a ref-walk. Again, if we can drop rcu-walk gracefully, we return -ECHILD and do the whole lookup using ref-walk. But it is very important that we can continue with ref-walk for most cases, particularly to avoid the overhead of double lookups, and to gain the scalability advantages on common path elements (like cwd and root). The cases where rcu-walk cannot continue are: * NULL dentry (ie. any uncached path element) * parent with d_inode->i_op->permission or ACLs * dentries with d_revalidate * Following links In future patches, permission checks and d_revalidate become rcu-walk aware. It may be possible eventually to make following links rcu-walk aware. Uncached path elements will always require dropping to ref-walk mode, at the very least because i_mutex needs to be grabbed, and objects allocated. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 09:49:52 +03:00
if (!inode)
return 1;
if (name->len != len)
return 1;
if (memcmp(name->name, str, len))
return 1;
head = rcu_dereference(PROC_I(inode)->sysctl);
return !head || !sysctl_is_seen(head);
}
static const struct dentry_operations proc_sys_dentry_operations = {
.d_revalidate = proc_sys_revalidate,
.d_delete = proc_sys_delete,
.d_compare = proc_sys_compare,
};
static struct ctl_dir *find_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
entry = find_entry(&head, dir, name, namelen);
if (!entry)
return ERR_PTR(-ENOENT);
if (!S_ISDIR(entry->mode))
return ERR_PTR(-ENOTDIR);
return container_of(head, struct ctl_dir, header);
}
static struct ctl_dir *new_dir(struct ctl_table_set *set,
const char *name, int namelen)
{
struct ctl_table *table;
struct ctl_dir *new;
struct ctl_node *node;
char *new_name;
new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
sizeof(struct ctl_table)*2 + namelen + 1,
GFP_KERNEL);
if (!new)
return NULL;
node = (struct ctl_node *)(new + 1);
table = (struct ctl_table *)(node + 1);
new_name = (char *)(table + 2);
memcpy(new_name, name, namelen);
new_name[namelen] = '\0';
table[0].procname = new_name;
table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
init_header(&new->header, set->dir.header.root, set, node, table);
return new;
}
/**
* get_subdir - find or create a subdir with the specified name.
* @dir: Directory to create the subdirectory in
* @name: The name of the subdirectory to find or create
* @namelen: The length of name
*
* Takes a directory with an elevated reference count so we know that
* if we drop the lock the directory will not go away. Upon success
* the reference is moved from @dir to the returned subdirectory.
* Upon error an error code is returned and the reference on @dir is
* simply dropped.
*/
static struct ctl_dir *get_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_set *set = dir->header.set;
struct ctl_dir *subdir, *new = NULL;
int err;
spin_lock(&sysctl_lock);
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
spin_unlock(&sysctl_lock);
new = new_dir(set, name, namelen);
spin_lock(&sysctl_lock);
subdir = ERR_PTR(-ENOMEM);
if (!new)
goto failed;
/* Was the subdir added while we dropped the lock? */
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
/* Nope. Use the our freshly made directory entry. */
err = insert_header(dir, &new->header);
subdir = ERR_PTR(err);
if (err)
goto failed;
subdir = new;
found:
subdir->header.nreg++;
failed:
if (IS_ERR(subdir)) {
pr_err("sysctl could not get directory: ");
sysctl_print_dir(dir);
pr_cont("/%*.*s %ld\n",
namelen, namelen, name, PTR_ERR(subdir));
}
drop_sysctl_table(&dir->header);
if (new)
drop_sysctl_table(&new->header);
spin_unlock(&sysctl_lock);
return subdir;
}
static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
{
struct ctl_dir *parent;
const char *procname;
if (!dir->header.parent)
return &set->dir;
parent = xlate_dir(set, dir->header.parent);
if (IS_ERR(parent))
return parent;
procname = dir->header.ctl_table[0].procname;
return find_subdir(parent, procname, strlen(procname));
}
static int sysctl_follow_link(struct ctl_table_header **phead,
struct ctl_table **pentry)
{
struct ctl_table_header *head;
struct ctl_table_root *root;
struct ctl_table_set *set;
struct ctl_table *entry;
struct ctl_dir *dir;
int ret;
ret = 0;
spin_lock(&sysctl_lock);
root = (*pentry)->data;
set = lookup_header_set(root);
dir = xlate_dir(set, (*phead)->parent);
if (IS_ERR(dir))
ret = PTR_ERR(dir);
else {
const char *procname = (*pentry)->procname;
head = NULL;
entry = find_entry(&head, dir, procname, strlen(procname));
ret = -ENOENT;
if (entry && use_table(head)) {
unuse_table(*phead);
*phead = head;
*pentry = entry;
ret = 0;
}
}
spin_unlock(&sysctl_lock);
return ret;
}
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
{
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
struct va_format vaf;
va_list args;
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("sysctl table check failed: %s/%s %pV\n",
path, table->procname, &vaf);
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
va_end(args);
return -EINVAL;
}
sysctl: simplify unsigned int support Commit e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") added proc_douintvec() to start help adding support for unsigned int, this however was only half the work needed. Two fixes have come in since then for the following issues: o Printing the values shows a negative value, this happens since do_proc_dointvec() and this uses proc_put_long() This was fixed by commit 5380e5644afbba9 ("sysctl: don't print negative flag for proc_douintvec"). o We can easily wrap around the int values: UINT_MAX is 4294967295, if we echo in 4294967295 + 1 we end up with 0, using 4294967295 + 2 we end up with 1. o We echo negative values in and they are accepted This was fixed by commit 425fffd886ba ("sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec"). It still also failed to be added to sysctl_check_table()... instead of adding it with the current implementation just provide a proper and simplified unsigned int support without any array unsigned int support with no negative support at all. Historically sysctl proc helpers have supported arrays, due to the complexity this adds though we've taken a step back to evaluate array users to determine if its worth upkeeping for unsigned int. An evaluation using Coccinelle has been done to perform a grammatical search to ask ourselves: o How many sysctl proc_dointvec() (int) users exist which likely should be moved over to proc_douintvec() (unsigned int) ? Answer: about 8 - Of these how many are array users ? Answer: Probably only 1 o How many sysctl array users exist ? Answer: about 12 This last question gives us an idea just how popular arrays: they are not. Array support should probably just be kept for strings. The identified uint ports are: drivers/infiniband/core/ucma.c - max_backlog drivers/infiniband/core/iwcm.c - default_backlog net/core/sysctl_net_core.c - rps_sock_flow_sysctl() net/netfilter/nf_conntrack_timestamp.c - nf_conntrack_timestamp -- bool net/netfilter/nf_conntrack_acct.c nf_conntrack_acct -- bool net/netfilter/nf_conntrack_ecache.c - nf_conntrack_events -- bool net/netfilter/nf_conntrack_helper.c - nf_conntrack_helper -- bool net/phonet/sysctl.c proc_local_port_range() The only possible array users is proc_local_port_range() but it does not seem worth it to add array support just for this given the range support works just as well. Unsigned int support should be desirable more for when you *need* more than INT_MAX or using int min/max support then does not suffice for your ranges. If you forget and by mistake happen to register an unsigned int proc entry with an array, the driver will fail and you will get something as follows: sysctl table check failed: debug/test_sysctl//uint_0002 array now allowed CPU: 2 PID: 1342 Comm: modprobe Tainted: G W E <etc> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS <etc> Call Trace: dump_stack+0x63/0x81 __register_sysctl_table+0x350/0x650 ? kmem_cache_alloc_trace+0x107/0x240 __register_sysctl_paths+0x1b3/0x1e0 ? 0xffffffffc005f000 register_sysctl_table+0x1f/0x30 test_sysctl_init+0x10/0x1000 [test_sysctl] do_one_initcall+0x52/0x1a0 ? kmem_cache_alloc_trace+0x107/0x240 do_init_module+0x5f/0x200 load_module+0x1867/0x1bd0 ? __symbol_put+0x60/0x60 SYSC_finit_module+0xdf/0x110 SyS_finit_module+0xe/0x10 entry_SYSCALL_64_fastpath+0x1e/0xad RIP: 0033:0x7f042b22d119 <etc> Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") Link: http://lkml.kernel.org/r/20170519033554.18592-5-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Suggested-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Cc: Liping Zhang <zlpnobody@gmail.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Kees Cook <keescook@chromium.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:36 +03:00
static int sysctl_check_table_array(const char *path, struct ctl_table *table)
{
int err = 0;
if ((table->proc_handler == proc_douintvec) ||
(table->proc_handler == proc_douintvec_minmax)) {
sysctl: simplify unsigned int support Commit e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") added proc_douintvec() to start help adding support for unsigned int, this however was only half the work needed. Two fixes have come in since then for the following issues: o Printing the values shows a negative value, this happens since do_proc_dointvec() and this uses proc_put_long() This was fixed by commit 5380e5644afbba9 ("sysctl: don't print negative flag for proc_douintvec"). o We can easily wrap around the int values: UINT_MAX is 4294967295, if we echo in 4294967295 + 1 we end up with 0, using 4294967295 + 2 we end up with 1. o We echo negative values in and they are accepted This was fixed by commit 425fffd886ba ("sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec"). It still also failed to be added to sysctl_check_table()... instead of adding it with the current implementation just provide a proper and simplified unsigned int support without any array unsigned int support with no negative support at all. Historically sysctl proc helpers have supported arrays, due to the complexity this adds though we've taken a step back to evaluate array users to determine if its worth upkeeping for unsigned int. An evaluation using Coccinelle has been done to perform a grammatical search to ask ourselves: o How many sysctl proc_dointvec() (int) users exist which likely should be moved over to proc_douintvec() (unsigned int) ? Answer: about 8 - Of these how many are array users ? Answer: Probably only 1 o How many sysctl array users exist ? Answer: about 12 This last question gives us an idea just how popular arrays: they are not. Array support should probably just be kept for strings. The identified uint ports are: drivers/infiniband/core/ucma.c - max_backlog drivers/infiniband/core/iwcm.c - default_backlog net/core/sysctl_net_core.c - rps_sock_flow_sysctl() net/netfilter/nf_conntrack_timestamp.c - nf_conntrack_timestamp -- bool net/netfilter/nf_conntrack_acct.c nf_conntrack_acct -- bool net/netfilter/nf_conntrack_ecache.c - nf_conntrack_events -- bool net/netfilter/nf_conntrack_helper.c - nf_conntrack_helper -- bool net/phonet/sysctl.c proc_local_port_range() The only possible array users is proc_local_port_range() but it does not seem worth it to add array support just for this given the range support works just as well. Unsigned int support should be desirable more for when you *need* more than INT_MAX or using int min/max support then does not suffice for your ranges. If you forget and by mistake happen to register an unsigned int proc entry with an array, the driver will fail and you will get something as follows: sysctl table check failed: debug/test_sysctl//uint_0002 array now allowed CPU: 2 PID: 1342 Comm: modprobe Tainted: G W E <etc> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS <etc> Call Trace: dump_stack+0x63/0x81 __register_sysctl_table+0x350/0x650 ? kmem_cache_alloc_trace+0x107/0x240 __register_sysctl_paths+0x1b3/0x1e0 ? 0xffffffffc005f000 register_sysctl_table+0x1f/0x30 test_sysctl_init+0x10/0x1000 [test_sysctl] do_one_initcall+0x52/0x1a0 ? kmem_cache_alloc_trace+0x107/0x240 do_init_module+0x5f/0x200 load_module+0x1867/0x1bd0 ? __symbol_put+0x60/0x60 SYSC_finit_module+0xdf/0x110 SyS_finit_module+0xe/0x10 entry_SYSCALL_64_fastpath+0x1e/0xad RIP: 0033:0x7f042b22d119 <etc> Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") Link: http://lkml.kernel.org/r/20170519033554.18592-5-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Suggested-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Cc: Liping Zhang <zlpnobody@gmail.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Kees Cook <keescook@chromium.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:36 +03:00
if (table->maxlen != sizeof(unsigned int))
err |= sysctl_err(path, table, "array now allowed");
}
return err;
}
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
static int sysctl_check_table(const char *path, struct ctl_table *table)
{
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
int err = 0;
for (; table->procname; table++) {
if (table->child)
sysctl: fix lax sysctl_check_table() sanity check Patch series "sysctl: few fixes", v5. I've been working on making kmod more deterministic, and as I did that I couldn't help but notice a few issues with sysctl. My end goal was just to fix unsigned int support, which back then was completely broken. Liping Zhang has sent up small atomic fixes, however it still missed yet one more fix and Alexey Dobriyan had also suggested to just drop array support given its complexity. I have inspected array support using Coccinelle and indeed its not that popular, so if in fact we can avoid it for new interfaces, I agree its best. I did develop a sysctl stress driver but will hold that off for another series. This patch (of 5): Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") improved sanity checks considerbly, however the enhancements on sysctl_check_table() meant adding a functional change so that only the last table entry's sanity error is propagated. It also changed the way errors were propagated so that each new check reset the err value, this means only last sanity check computed is used for an error. This has been in the kernel since v3.4 days. Fix this by carrying on errors from previous checks and iterations as we traverse the table and ensuring we keep any error from previous checks. We keep iterating on the table even if an error is found so we can complain for all errors found in one shot. This works as -EINVAL is always returned on error anyway, and the check for error is any non-zero value. Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:27 +03:00
err |= sysctl_err(path, table, "Not a file");
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
if ((table->proc_handler == proc_dostring) ||
(table->proc_handler == proc_dointvec) ||
(table->proc_handler == proc_douintvec) ||
(table->proc_handler == proc_douintvec_minmax) ||
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
(table->proc_handler == proc_dointvec_minmax) ||
(table->proc_handler == proc_dointvec_jiffies) ||
(table->proc_handler == proc_dointvec_userhz_jiffies) ||
(table->proc_handler == proc_dointvec_ms_jiffies) ||
(table->proc_handler == proc_doulongvec_minmax) ||
(table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
if (!table->data)
sysctl: fix lax sysctl_check_table() sanity check Patch series "sysctl: few fixes", v5. I've been working on making kmod more deterministic, and as I did that I couldn't help but notice a few issues with sysctl. My end goal was just to fix unsigned int support, which back then was completely broken. Liping Zhang has sent up small atomic fixes, however it still missed yet one more fix and Alexey Dobriyan had also suggested to just drop array support given its complexity. I have inspected array support using Coccinelle and indeed its not that popular, so if in fact we can avoid it for new interfaces, I agree its best. I did develop a sysctl stress driver but will hold that off for another series. This patch (of 5): Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") improved sanity checks considerbly, however the enhancements on sysctl_check_table() meant adding a functional change so that only the last table entry's sanity error is propagated. It also changed the way errors were propagated so that each new check reset the err value, this means only last sanity check computed is used for an error. This has been in the kernel since v3.4 days. Fix this by carrying on errors from previous checks and iterations as we traverse the table and ensuring we keep any error from previous checks. We keep iterating on the table even if an error is found so we can complain for all errors found in one shot. This works as -EINVAL is always returned on error anyway, and the check for error is any non-zero value. Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:27 +03:00
err |= sysctl_err(path, table, "No data");
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
if (!table->maxlen)
sysctl: fix lax sysctl_check_table() sanity check Patch series "sysctl: few fixes", v5. I've been working on making kmod more deterministic, and as I did that I couldn't help but notice a few issues with sysctl. My end goal was just to fix unsigned int support, which back then was completely broken. Liping Zhang has sent up small atomic fixes, however it still missed yet one more fix and Alexey Dobriyan had also suggested to just drop array support given its complexity. I have inspected array support using Coccinelle and indeed its not that popular, so if in fact we can avoid it for new interfaces, I agree its best. I did develop a sysctl stress driver but will hold that off for another series. This patch (of 5): Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") improved sanity checks considerbly, however the enhancements on sysctl_check_table() meant adding a functional change so that only the last table entry's sanity error is propagated. It also changed the way errors were propagated so that each new check reset the err value, this means only last sanity check computed is used for an error. This has been in the kernel since v3.4 days. Fix this by carrying on errors from previous checks and iterations as we traverse the table and ensuring we keep any error from previous checks. We keep iterating on the table even if an error is found so we can complain for all errors found in one shot. This works as -EINVAL is always returned on error anyway, and the check for error is any non-zero value. Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:27 +03:00
err |= sysctl_err(path, table, "No maxlen");
sysctl: simplify unsigned int support Commit e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") added proc_douintvec() to start help adding support for unsigned int, this however was only half the work needed. Two fixes have come in since then for the following issues: o Printing the values shows a negative value, this happens since do_proc_dointvec() and this uses proc_put_long() This was fixed by commit 5380e5644afbba9 ("sysctl: don't print negative flag for proc_douintvec"). o We can easily wrap around the int values: UINT_MAX is 4294967295, if we echo in 4294967295 + 1 we end up with 0, using 4294967295 + 2 we end up with 1. o We echo negative values in and they are accepted This was fixed by commit 425fffd886ba ("sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec"). It still also failed to be added to sysctl_check_table()... instead of adding it with the current implementation just provide a proper and simplified unsigned int support without any array unsigned int support with no negative support at all. Historically sysctl proc helpers have supported arrays, due to the complexity this adds though we've taken a step back to evaluate array users to determine if its worth upkeeping for unsigned int. An evaluation using Coccinelle has been done to perform a grammatical search to ask ourselves: o How many sysctl proc_dointvec() (int) users exist which likely should be moved over to proc_douintvec() (unsigned int) ? Answer: about 8 - Of these how many are array users ? Answer: Probably only 1 o How many sysctl array users exist ? Answer: about 12 This last question gives us an idea just how popular arrays: they are not. Array support should probably just be kept for strings. The identified uint ports are: drivers/infiniband/core/ucma.c - max_backlog drivers/infiniband/core/iwcm.c - default_backlog net/core/sysctl_net_core.c - rps_sock_flow_sysctl() net/netfilter/nf_conntrack_timestamp.c - nf_conntrack_timestamp -- bool net/netfilter/nf_conntrack_acct.c nf_conntrack_acct -- bool net/netfilter/nf_conntrack_ecache.c - nf_conntrack_events -- bool net/netfilter/nf_conntrack_helper.c - nf_conntrack_helper -- bool net/phonet/sysctl.c proc_local_port_range() The only possible array users is proc_local_port_range() but it does not seem worth it to add array support just for this given the range support works just as well. Unsigned int support should be desirable more for when you *need* more than INT_MAX or using int min/max support then does not suffice for your ranges. If you forget and by mistake happen to register an unsigned int proc entry with an array, the driver will fail and you will get something as follows: sysctl table check failed: debug/test_sysctl//uint_0002 array now allowed CPU: 2 PID: 1342 Comm: modprobe Tainted: G W E <etc> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS <etc> Call Trace: dump_stack+0x63/0x81 __register_sysctl_table+0x350/0x650 ? kmem_cache_alloc_trace+0x107/0x240 __register_sysctl_paths+0x1b3/0x1e0 ? 0xffffffffc005f000 register_sysctl_table+0x1f/0x30 test_sysctl_init+0x10/0x1000 [test_sysctl] do_one_initcall+0x52/0x1a0 ? kmem_cache_alloc_trace+0x107/0x240 do_init_module+0x5f/0x200 load_module+0x1867/0x1bd0 ? __symbol_put+0x60/0x60 SYSC_finit_module+0xdf/0x110 SyS_finit_module+0xe/0x10 entry_SYSCALL_64_fastpath+0x1e/0xad RIP: 0033:0x7f042b22d119 <etc> Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") Link: http://lkml.kernel.org/r/20170519033554.18592-5-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Suggested-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Cc: Liping Zhang <zlpnobody@gmail.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Kees Cook <keescook@chromium.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:36 +03:00
else
err |= sysctl_check_table_array(path, table);
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
}
if (!table->proc_handler)
sysctl: fix lax sysctl_check_table() sanity check Patch series "sysctl: few fixes", v5. I've been working on making kmod more deterministic, and as I did that I couldn't help but notice a few issues with sysctl. My end goal was just to fix unsigned int support, which back then was completely broken. Liping Zhang has sent up small atomic fixes, however it still missed yet one more fix and Alexey Dobriyan had also suggested to just drop array support given its complexity. I have inspected array support using Coccinelle and indeed its not that popular, so if in fact we can avoid it for new interfaces, I agree its best. I did develop a sysctl stress driver but will hold that off for another series. This patch (of 5): Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") improved sanity checks considerbly, however the enhancements on sysctl_check_table() meant adding a functional change so that only the last table entry's sanity error is propagated. It also changed the way errors were propagated so that each new check reset the err value, this means only last sanity check computed is used for an error. This has been in the kernel since v3.4 days. Fix this by carrying on errors from previous checks and iterations as we traverse the table and ensuring we keep any error from previous checks. We keep iterating on the table even if an error is found so we can complain for all errors found in one shot. This works as -EINVAL is always returned on error anyway, and the check for error is any non-zero value. Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:27 +03:00
err |= sysctl_err(path, table, "No proc_handler");
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
sysctl: fix lax sysctl_check_table() sanity check Patch series "sysctl: few fixes", v5. I've been working on making kmod more deterministic, and as I did that I couldn't help but notice a few issues with sysctl. My end goal was just to fix unsigned int support, which back then was completely broken. Liping Zhang has sent up small atomic fixes, however it still missed yet one more fix and Alexey Dobriyan had also suggested to just drop array support given its complexity. I have inspected array support using Coccinelle and indeed its not that popular, so if in fact we can avoid it for new interfaces, I agree its best. I did develop a sysctl stress driver but will hold that off for another series. This patch (of 5): Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") improved sanity checks considerbly, however the enhancements on sysctl_check_table() meant adding a functional change so that only the last table entry's sanity error is propagated. It also changed the way errors were propagated so that each new check reset the err value, this means only last sanity check computed is used for an error. This has been in the kernel since v3.4 days. Fix this by carrying on errors from previous checks and iterations as we traverse the table and ensuring we keep any error from previous checks. We keep iterating on the table even if an error is found so we can complain for all errors found in one shot. This works as -EINVAL is always returned on error anyway, and the check for error is any non-zero value. Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks") Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 00:33:27 +03:00
err |= sysctl_err(path, table, "bogus .mode 0%o",
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
table->mode);
}
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
return err;
}
static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
struct ctl_table_root *link_root)
{
struct ctl_table *link_table, *entry, *link;
struct ctl_table_header *links;
struct ctl_node *node;
char *link_name;
int nr_entries, name_bytes;
name_bytes = 0;
nr_entries = 0;
for (entry = table; entry->procname; entry++) {
nr_entries++;
name_bytes += strlen(entry->procname) + 1;
}
links = kzalloc(sizeof(struct ctl_table_header) +
sizeof(struct ctl_node)*nr_entries +
sizeof(struct ctl_table)*(nr_entries + 1) +
name_bytes,
GFP_KERNEL);
if (!links)
return NULL;
node = (struct ctl_node *)(links + 1);
link_table = (struct ctl_table *)(node + nr_entries);
link_name = (char *)&link_table[nr_entries + 1];
for (link = link_table, entry = table; entry->procname; link++, entry++) {
int len = strlen(entry->procname) + 1;
memcpy(link_name, entry->procname, len);
link->procname = link_name;
link->mode = S_IFLNK|S_IRWXUGO;
link->data = link_root;
link_name += len;
}
init_header(links, dir->header.root, dir->header.set, node, link_table);
links->nreg = nr_entries;
return links;
}
static bool get_links(struct ctl_dir *dir,
struct ctl_table *table, struct ctl_table_root *link_root)
{
struct ctl_table_header *head;
struct ctl_table *entry, *link;
/* Are there links available for every entry in table? */
for (entry = table; entry->procname; entry++) {
const char *procname = entry->procname;
link = find_entry(&head, dir, procname, strlen(procname));
if (!link)
return false;
if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
continue;
if (S_ISLNK(link->mode) && (link->data == link_root))
continue;
return false;
}
/* The checks passed. Increase the registration count on the links */
for (entry = table; entry->procname; entry++) {
const char *procname = entry->procname;
link = find_entry(&head, dir, procname, strlen(procname));
head->nreg++;
}
return true;
}
static int insert_links(struct ctl_table_header *head)
{
struct ctl_table_set *root_set = &sysctl_table_root.default_set;
struct ctl_dir *core_parent = NULL;
struct ctl_table_header *links;
int err;
if (head->set == root_set)
return 0;
core_parent = xlate_dir(root_set, head->parent);
if (IS_ERR(core_parent))
return 0;
if (get_links(core_parent, head->ctl_table, head->root))
return 0;
core_parent->header.nreg++;
spin_unlock(&sysctl_lock);
links = new_links(core_parent, head->ctl_table, head->root);
spin_lock(&sysctl_lock);
err = -ENOMEM;
if (!links)
goto out;
err = 0;
if (get_links(core_parent, head->ctl_table, head->root)) {
kfree(links);
goto out;
}
err = insert_header(core_parent, links);
if (err)
kfree(links);
out:
drop_sysctl_table(&core_parent->header);
return err;
}
/**
* __register_sysctl_table - register a leaf sysctl table
* @set: Sysctl tree to register on
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* The members of the &struct ctl_table structure are used as follows:
*
* procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
* enter a sysctl file
*
* data - a pointer to data for use by proc_handler
*
* maxlen - the maximum size in bytes of the data
*
* mode - the file permissions for the /proc/sys file
*
* child - must be %NULL.
*
* proc_handler - the text handler routine (described below)
*
* extra1, extra2 - extra pointers usable by the proc handler routines
*
* Leaf nodes in the sysctl tree will be represented by a single file
* under /proc; non-leaf nodes will be represented by directories.
*
* There must be a proc_handler routine for any terminal nodes.
* Several default handlers are available to cover common cases -
*
* proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
* proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
* proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
*
* It is the handler's job to read the input buffer from user memory
* and process it. The handler should return 0 on success.
*
* This routine returns %NULL on a failure to register, and a pointer
* to the table header on success.
*/
struct ctl_table_header *__register_sysctl_table(
struct ctl_table_set *set,
const char *path, struct ctl_table *table)
{
struct ctl_table_root *root = set->dir.header.root;
struct ctl_table_header *header;
const char *name, *nextname;
struct ctl_dir *dir;
struct ctl_table *entry;
struct ctl_node *node;
int nr_entries = 0;
for (entry = table; entry->procname; entry++)
nr_entries++;
header = kzalloc(sizeof(struct ctl_table_header) +
sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
if (!header)
return NULL;
node = (struct ctl_node *)(header + 1);
init_header(header, root, set, node, table);
if (sysctl_check_table(path, table))
goto fail;
spin_lock(&sysctl_lock);
dir = &set->dir;
/* Reference moved down the diretory tree get_subdir */
dir->header.nreg++;
spin_unlock(&sysctl_lock);
/* Find the directory for the ctl_table */
for (name = path; name; name = nextname) {
int namelen;
nextname = strchr(name, '/');
if (nextname) {
namelen = nextname - name;
nextname++;
} else {
namelen = strlen(name);
}
if (namelen == 0)
continue;
dir = get_subdir(dir, name, namelen);
if (IS_ERR(dir))
goto fail;
}
spin_lock(&sysctl_lock);
if (insert_header(dir, header))
goto fail_put_dir_locked;
drop_sysctl_table(&dir->header);
spin_unlock(&sysctl_lock);
return header;
fail_put_dir_locked:
drop_sysctl_table(&dir->header);
sysctl: Improve the sysctl sanity checks - Stop validating subdirectories now that we only register leaf tables - Cleanup and improve the duplicate filename check. * Run the duplicate filename check under the sysctl_lock to guarantee we never add duplicate names. * Reduce the duplicate filename check to nearly O(M*N) where M is the number of entries in tthe table we are registering and N is the number of entries in the directory before we got there. - Move the duplicate filename check into it's own function and call it directtly from __register_sysctl_table - Kill the config option as the sanity checks are now cheap enough the config option is unnecessary. The original reason for the config option was because we had a huge table used to verify the proc filename to binary sysctl mapping. That table has now evolved into the binary_sysctl translation layer and is no longer part of the sysctl_check code. - Tighten up the permission checks. Guarnateeing that files only have read or write permissions. - Removed redudant check for parents having a procname as now everything has a procname. - Generalize the backtrace logic so that we print a backtrace from any failure of __register_sysctl_table that was not caused by a memmory allocation failure. The backtrace allows us to track down who erroneously registered a sysctl table. Bechmark before (CONFIG_SYSCTL_CHECK=y): make-dummies 0 999 -> 12s rmmod dummy -> 0.08s Bechmark before (CONFIG_SYSCTL_CHECK=n): make-dummies 0 999 -> 0.7s rmmod dummy -> 0.06s make-dummies 0 99999 -> 1m13s rmmod dummy -> 0.38s Benchmark after: make-dummies 0 999 -> 0.65s rmmod dummy -> 0.055s make-dummies 0 9999 -> 1m10s rmmod dummy -> 0.39s The sysctl sanity checks now impose no measurable cost. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-22 01:34:05 +04:00
spin_unlock(&sysctl_lock);
fail:
kfree(header);
dump_stack();
return NULL;
}
/**
* register_sysctl - register a sysctl table
* @path: The path to the directory the sysctl table is in.
* @table: the table structure
*
* Register a sysctl table. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_table for more details.
*/
struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
{
return __register_sysctl_table(&sysctl_table_root.default_set,
path, table);
}
EXPORT_SYMBOL(register_sysctl);
static char *append_path(const char *path, char *pos, const char *name)
{
int namelen;
namelen = strlen(name);
if (((pos - path) + namelen + 2) >= PATH_MAX)
return NULL;
memcpy(pos, name, namelen);
pos[namelen] = '/';
pos[namelen + 1] = '\0';
pos += namelen + 1;
return pos;
}
static int count_subheaders(struct ctl_table *table)
{
int has_files = 0;
int nr_subheaders = 0;
struct ctl_table *entry;
/* special case: no directory and empty directory */
if (!table || !table->procname)
return 1;
for (entry = table; entry->procname; entry++) {
if (entry->child)
nr_subheaders += count_subheaders(entry->child);
else
has_files = 1;
}
return nr_subheaders + has_files;
}
static int register_leaf_sysctl_tables(const char *path, char *pos,
struct ctl_table_header ***subheader, struct ctl_table_set *set,
struct ctl_table *table)
{
struct ctl_table *ctl_table_arg = NULL;
struct ctl_table *entry, *files;
int nr_files = 0;
int nr_dirs = 0;
int err = -ENOMEM;
for (entry = table; entry->procname; entry++) {
if (entry->child)
nr_dirs++;
else
nr_files++;
}
files = table;
/* If there are mixed files and directories we need a new table */
if (nr_dirs && nr_files) {
struct ctl_table *new;
files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
GFP_KERNEL);
if (!files)
goto out;
ctl_table_arg = files;
for (new = files, entry = table; entry->procname; entry++) {
if (entry->child)
continue;
*new = *entry;
new++;
}
}
/* Register everything except a directory full of subdirectories */
if (nr_files || !nr_dirs) {
struct ctl_table_header *header;
header = __register_sysctl_table(set, path, files);
if (!header) {
kfree(ctl_table_arg);
goto out;
}
/* Remember if we need to free the file table */
header->ctl_table_arg = ctl_table_arg;
**subheader = header;
(*subheader)++;
}
/* Recurse into the subdirectories. */
for (entry = table; entry->procname; entry++) {
char *child_pos;
if (!entry->child)
continue;
err = -ENAMETOOLONG;
child_pos = append_path(path, pos, entry->procname);
if (!child_pos)
goto out;
err = register_leaf_sysctl_tables(path, child_pos, subheader,
set, entry->child);
pos[0] = '\0';
if (err)
goto out;
}
err = 0;
out:
/* On failure our caller will unregister all registered subheaders */
return err;
}
/**
* __register_sysctl_paths - register a sysctl table hierarchy
* @set: Sysctl tree to register on
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_table for more details.
*/
struct ctl_table_header *__register_sysctl_paths(
struct ctl_table_set *set,
const struct ctl_path *path, struct ctl_table *table)
{
struct ctl_table *ctl_table_arg = table;
int nr_subheaders = count_subheaders(table);
struct ctl_table_header *header = NULL, **subheaders, **subheader;
const struct ctl_path *component;
char *new_path, *pos;
pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
if (!new_path)
return NULL;
pos[0] = '\0';
for (component = path; component->procname; component++) {
pos = append_path(new_path, pos, component->procname);
if (!pos)
goto out;
}
while (table->procname && table->child && !table[1].procname) {
pos = append_path(new_path, pos, table->procname);
if (!pos)
goto out;
table = table->child;
}
if (nr_subheaders == 1) {
header = __register_sysctl_table(set, new_path, table);
if (header)
header->ctl_table_arg = ctl_table_arg;
} else {
header = kzalloc(sizeof(*header) +
sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
if (!header)
goto out;
subheaders = (struct ctl_table_header **) (header + 1);
subheader = subheaders;
header->ctl_table_arg = ctl_table_arg;
if (register_leaf_sysctl_tables(new_path, pos, &subheader,
set, table))
goto err_register_leaves;
}
out:
kfree(new_path);
return header;
err_register_leaves:
while (subheader > subheaders) {
struct ctl_table_header *subh = *(--subheader);
struct ctl_table *table = subh->ctl_table_arg;
unregister_sysctl_table(subh);
kfree(table);
}
kfree(header);
header = NULL;
goto out;
}
/**
* register_sysctl_table_path - register a sysctl table hierarchy
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_paths for more details.
*/
struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
struct ctl_table *table)
{
return __register_sysctl_paths(&sysctl_table_root.default_set,
path, table);
}
EXPORT_SYMBOL(register_sysctl_paths);
/**
* register_sysctl_table - register a sysctl table hierarchy
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See register_sysctl_paths for more details.
*/
struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
{
static const struct ctl_path null_path[] = { {} };
return register_sysctl_paths(null_path, table);
}
EXPORT_SYMBOL(register_sysctl_table);
static void put_links(struct ctl_table_header *header)
{
struct ctl_table_set *root_set = &sysctl_table_root.default_set;
struct ctl_table_root *root = header->root;
struct ctl_dir *parent = header->parent;
struct ctl_dir *core_parent;
struct ctl_table *entry;
if (header->set == root_set)
return;
core_parent = xlate_dir(root_set, parent);
if (IS_ERR(core_parent))
return;
for (entry = header->ctl_table; entry->procname; entry++) {
struct ctl_table_header *link_head;
struct ctl_table *link;
const char *name = entry->procname;
link = find_entry(&link_head, core_parent, name, strlen(name));
if (link &&
((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
(S_ISLNK(link->mode) && (link->data == root)))) {
drop_sysctl_table(link_head);
}
else {
pr_err("sysctl link missing during unregister: ");
sysctl_print_dir(parent);
pr_cont("/%s\n", name);
}
}
}
static void drop_sysctl_table(struct ctl_table_header *header)
{
struct ctl_dir *parent = header->parent;
if (--header->nreg)
return;
put_links(header);
start_unregistering(header);
if (!--header->count)
kfree_rcu(header, rcu);
if (parent)
drop_sysctl_table(&parent->header);
}
/**
* unregister_sysctl_table - unregister a sysctl table hierarchy
* @header: the header returned from register_sysctl_table
*
* Unregisters the sysctl table and all children. proc entries may not
* actually be removed until they are no longer used by anyone.
*/
void unregister_sysctl_table(struct ctl_table_header * header)
{
int nr_subheaders;
might_sleep();
if (header == NULL)
return;
nr_subheaders = count_subheaders(header->ctl_table_arg);
if (unlikely(nr_subheaders > 1)) {
struct ctl_table_header **subheaders;
int i;
subheaders = (struct ctl_table_header **)(header + 1);
for (i = nr_subheaders -1; i >= 0; i--) {
struct ctl_table_header *subh = subheaders[i];
struct ctl_table *table = subh->ctl_table_arg;
unregister_sysctl_table(subh);
kfree(table);
}
kfree(header);
return;
}
spin_lock(&sysctl_lock);
drop_sysctl_table(header);
spin_unlock(&sysctl_lock);
}
EXPORT_SYMBOL(unregister_sysctl_table);
void setup_sysctl_set(struct ctl_table_set *set,
struct ctl_table_root *root,
int (*is_seen)(struct ctl_table_set *))
{
memset(set, 0, sizeof(*set));
set->is_seen = is_seen;
init_header(&set->dir.header, root, set, NULL, root_table);
}
void retire_sysctl_set(struct ctl_table_set *set)
{
WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
}
int __init proc_sys_init(void)
{
struct proc_dir_entry *proc_sys_root;
proc_sys_root = proc_mkdir("sys", NULL);
proc_sys_root->proc_iops = &proc_sys_dir_operations;
proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
proc_sys_root->nlink = 0;
return sysctl_init();
}