WSL2-Linux-Kernel/fs/devpts/inode.c

601 строка
14 KiB
C
Исходник Обычный вид История

/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/inode.c
*
* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 11:04:11 +03:00
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/mutex.h>
#include <linux/magic.h>
#include <linux/idr.h>
#include <linux/devpts_fs.h>
#include <linux/parser.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
#define DEVPTS_DEFAULT_MODE 0600
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
/*
* ptmx is a new node in /dev/pts and will be unused in legacy (single-
* instance) mode. To prevent surprises in user space, set permissions of
* ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
* permissions.
*/
#define DEVPTS_DEFAULT_PTMX_MODE 0000
#define PTMX_MINOR 2
/*
* sysctl support for setting limits on the number of Unix98 ptys allocated.
* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
*/
static int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_reserve = NR_UNIX98_PTY_RESERVE;
static int pty_limit_min;
static int pty_limit_max = INT_MAX;
static int pty_count;
static struct ctl_table pty_table[] = {
{
.procname = "max",
.maxlen = sizeof(int),
.mode = 0644,
.data = &pty_limit,
.proc_handler = proc_dointvec_minmax,
.extra1 = &pty_limit_min,
.extra2 = &pty_limit_max,
}, {
.procname = "reserve",
.maxlen = sizeof(int),
.mode = 0644,
.data = &pty_reserve,
.proc_handler = proc_dointvec_minmax,
.extra1 = &pty_limit_min,
.extra2 = &pty_limit_max,
}, {
.procname = "nr",
.maxlen = sizeof(int),
.mode = 0444,
.data = &pty_count,
.proc_handler = proc_dointvec,
},
{}
};
static struct ctl_table pty_kern_table[] = {
{
.procname = "pty",
.mode = 0555,
.child = pty_table,
},
{}
};
static struct ctl_table pty_root_table[] = {
{
.procname = "kernel",
.mode = 0555,
.child = pty_kern_table,
},
{}
};
static DEFINE_MUTEX(allocated_ptys_lock);
struct pts_mount_opts {
int setuid;
int setgid;
kuid_t uid;
kgid_t gid;
umode_t mode;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
umode_t ptmxmode;
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
int reserve;
int max;
};
enum {
Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max,
Opt_err
};
static const match_table_t tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
{Opt_ptmxmode, "ptmxmode=%o"},
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
{Opt_newinstance, "newinstance"},
{Opt_max, "max=%d"},
{Opt_err, NULL}
};
struct pts_fs_info {
struct ida allocated_ptys;
struct pts_mount_opts mount_opts;
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
struct super_block *sb;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
struct dentry *ptmx_dentry;
};
static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
{
return sb->s_fs_info;
}
pty: fix the cached path of the pty slave file descriptor in the master Christian Brauner reported that if you use the TIOCGPTPEER ioctl() to get a slave pty file descriptor, the resulting file descriptor doesn't look right in /proc/<pid>/fd/<fd>. In particular, he wanted to use readlink() on /proc/self/fd/<fd> to get the pathname of the slave pty (basically implementing "ptsname{_r}()"). The reason for that was that we had generated the wrong 'struct path' when we create the pty in ptmx_open(). In particular, the dentry was correct, but the vfsmount pointed to the mount of the ptmx node. That _can_ be correct - in case you use "/dev/pts/ptmx" to open the master - but usually is not. The normal case is to use /dev/ptmx, which then looks up the pts/ directory, and then the vfsmount of the ptmx node is obviously the /dev directory, not the /dev/pts/ directory. We actually did have the right vfsmount available, but in the wrong place (it gets looked up in 'devpts_acquire()' when we get a reference to the pts filesystem), and so ptmx_open() used the wrong mnt pointer. The end result of this confusion was that the pty worked fine, but when if you did TIOCGPTPEER to get the slave side of the pty, end end result would also work, but have that dodgy 'struct path'. And then when doing "d_path()" on to get the pathname, the vfsmount would not match the root of the pts directory, and d_path() would return an empty pathname thinking that the entry had escaped a bind mount into another mount. This fixes the problem by making devpts_acquire() return the vfsmount for the pts filesystem, allowing ptmx_open() to trivially just use the right mount for the pts dentry, and create the proper 'struct path'. Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-17 03:08:07 +03:00
struct pts_fs_info *devpts_acquire(struct file *filp, struct vfsmount **ptsmnt)
{
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
struct pts_fs_info *result;
struct path path;
struct super_block *sb;
int err;
path = filp->f_path;
path_get(&path);
pty: fix the cached path of the pty slave file descriptor in the master Christian Brauner reported that if you use the TIOCGPTPEER ioctl() to get a slave pty file descriptor, the resulting file descriptor doesn't look right in /proc/<pid>/fd/<fd>. In particular, he wanted to use readlink() on /proc/self/fd/<fd> to get the pathname of the slave pty (basically implementing "ptsname{_r}()"). The reason for that was that we had generated the wrong 'struct path' when we create the pty in ptmx_open(). In particular, the dentry was correct, but the vfsmount pointed to the mount of the ptmx node. That _can_ be correct - in case you use "/dev/pts/ptmx" to open the master - but usually is not. The normal case is to use /dev/ptmx, which then looks up the pts/ directory, and then the vfsmount of the ptmx node is obviously the /dev directory, not the /dev/pts/ directory. We actually did have the right vfsmount available, but in the wrong place (it gets looked up in 'devpts_acquire()' when we get a reference to the pts filesystem), and so ptmx_open() used the wrong mnt pointer. The end result of this confusion was that the pty worked fine, but when if you did TIOCGPTPEER to get the slave side of the pty, end end result would also work, but have that dodgy 'struct path'. And then when doing "d_path()" on to get the pathname, the vfsmount would not match the root of the pts directory, and d_path() would return an empty pathname thinking that the entry had escaped a bind mount into another mount. This fixes the problem by making devpts_acquire() return the vfsmount for the pts filesystem, allowing ptmx_open() to trivially just use the right mount for the pts dentry, and create the proper 'struct path'. Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-17 03:08:07 +03:00
*ptsmnt = NULL;
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
/* Has the devpts filesystem already been found? */
sb = path.mnt->mnt_sb;
if (sb->s_magic != DEVPTS_SUPER_MAGIC) {
/* Is a devpts filesystem at "pts" in the same directory? */
err = path_pts(&path);
if (err) {
result = ERR_PTR(err);
goto out;
}
/* Is the path the root of a devpts filesystem? */
result = ERR_PTR(-ENODEV);
sb = path.mnt->mnt_sb;
if ((sb->s_magic != DEVPTS_SUPER_MAGIC) ||
(path.mnt->mnt_root != sb->s_root))
goto out;
}
/*
* pty code needs to hold extra references in case of last /dev/tty close
*/
atomic_inc(&sb->s_active);
pty: fix the cached path of the pty slave file descriptor in the master Christian Brauner reported that if you use the TIOCGPTPEER ioctl() to get a slave pty file descriptor, the resulting file descriptor doesn't look right in /proc/<pid>/fd/<fd>. In particular, he wanted to use readlink() on /proc/self/fd/<fd> to get the pathname of the slave pty (basically implementing "ptsname{_r}()"). The reason for that was that we had generated the wrong 'struct path' when we create the pty in ptmx_open(). In particular, the dentry was correct, but the vfsmount pointed to the mount of the ptmx node. That _can_ be correct - in case you use "/dev/pts/ptmx" to open the master - but usually is not. The normal case is to use /dev/ptmx, which then looks up the pts/ directory, and then the vfsmount of the ptmx node is obviously the /dev directory, not the /dev/pts/ directory. We actually did have the right vfsmount available, but in the wrong place (it gets looked up in 'devpts_acquire()' when we get a reference to the pts filesystem), and so ptmx_open() used the wrong mnt pointer. The end result of this confusion was that the pty worked fine, but when if you did TIOCGPTPEER to get the slave side of the pty, end end result would also work, but have that dodgy 'struct path'. And then when doing "d_path()" on to get the pathname, the vfsmount would not match the root of the pts directory, and d_path() would return an empty pathname thinking that the entry had escaped a bind mount into another mount. This fixes the problem by making devpts_acquire() return the vfsmount for the pts filesystem, allowing ptmx_open() to trivially just use the right mount for the pts dentry, and create the proper 'struct path'. Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-17 03:08:07 +03:00
*ptsmnt = mntget(path.mnt);
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
result = DEVPTS_SB(sb);
out:
path_put(&path);
return result;
}
void devpts_release(struct pts_fs_info *fsi)
{
deactivate_super(fsi->sb);
}
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
#define PARSE_MOUNT 0
#define PARSE_REMOUNT 1
/*
* parse_mount_options():
* Set @opts to mount options specified in @data. If an option is not
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
* specified in @data, set it to its default value.
*
* Note: @data may be NULL (in which case all options are set to default).
*/
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
{
char *p;
kuid_t uid;
kgid_t gid;
opts->setuid = 0;
opts->setgid = 0;
opts->uid = GLOBAL_ROOT_UID;
opts->gid = GLOBAL_ROOT_GID;
opts->mode = DEVPTS_DEFAULT_MODE;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
opts->max = NR_UNIX98_PTY_MAX;
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
/* Only allow instances mounted from the initial mount
* namespace to tap the reserve pool of ptys.
*/
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
if (op == PARSE_MOUNT)
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
opts->reserve =
(current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns);
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
while ((p = strsep(&data, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
int token;
int option;
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
uid = make_kuid(current_user_ns(), option);
if (!uid_valid(uid))
return -EINVAL;
opts->uid = uid;
opts->setuid = 1;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
gid = make_kgid(current_user_ns(), option);
if (!gid_valid(gid))
return -EINVAL;
opts->gid = gid;
opts->setgid = 1;
break;
case Opt_mode:
if (match_octal(&args[0], &option))
return -EINVAL;
opts->mode = option & S_IALLUGO;
break;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
case Opt_ptmxmode:
if (match_octal(&args[0], &option))
return -EINVAL;
opts->ptmxmode = option & S_IALLUGO;
break;
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
case Opt_newinstance:
break;
case Opt_max:
if (match_int(&args[0], &option) ||
option < 0 || option > NR_UNIX98_PTY_MAX)
return -EINVAL;
opts->max = option;
break;
default:
pr_err("called with bogus options\n");
return -EINVAL;
}
}
return 0;
}
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
static int mknod_ptmx(struct super_block *sb)
{
int mode;
int rc = -ENOMEM;
struct dentry *dentry;
struct inode *inode;
struct dentry *root = sb->s_root;
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = &fsi->mount_opts;
kuid_t ptmx_uid = current_fsuid();
kgid_t ptmx_gid = current_fsgid();
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
inode_lock(d_inode(root));
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
/* If we have already created ptmx node, return */
if (fsi->ptmx_dentry) {
rc = 0;
goto out;
}
dentry = d_alloc_name(root, "ptmx");
if (!dentry) {
pr_err("Unable to alloc dentry for ptmx node\n");
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
goto out;
}
/*
* Create a new 'ptmx' node in this mount of devpts.
*/
inode = new_inode(sb);
if (!inode) {
pr_err("Unable to alloc inode for ptmx node\n");
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
dput(dentry);
goto out;
}
inode->i_ino = 2;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
mode = S_IFCHR|opts->ptmxmode;
init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
inode->i_uid = ptmx_uid;
inode->i_gid = ptmx_gid;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
d_add(dentry, inode);
fsi->ptmx_dentry = dentry;
rc = 0;
out:
inode_unlock(d_inode(root));
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
return rc;
}
static void update_ptmx_mode(struct pts_fs_info *fsi)
{
struct inode *inode;
if (fsi->ptmx_dentry) {
inode = d_inode(fsi->ptmx_dentry);
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
}
}
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
int err;
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = &fsi->mount_opts;
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
err = parse_mount_options(data, PARSE_REMOUNT, opts);
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
/*
* parse_mount_options() restores options to default values
* before parsing and may have changed ptmxmode. So, update the
* mode in the inode too. Bogus options don't fail the remount,
* so do this even on error return.
*/
update_ptmx_mode(fsi);
return err;
}
static int devpts_show_options(struct seq_file *seq, struct dentry *root)
{
struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb);
struct pts_mount_opts *opts = &fsi->mount_opts;
if (opts->setuid)
seq_printf(seq, ",uid=%u",
from_kuid_munged(&init_user_ns, opts->uid));
if (opts->setgid)
seq_printf(seq, ",gid=%u",
from_kgid_munged(&init_user_ns, opts->gid));
seq_printf(seq, ",mode=%03o", opts->mode);
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
if (opts->max < NR_UNIX98_PTY_MAX)
seq_printf(seq, ",max=%d", opts->max);
return 0;
}
static const struct super_operations devpts_sops = {
.statfs = simple_statfs,
.remount_fs = devpts_remount,
.show_options = devpts_show_options,
};
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
static void *new_pts_fs_info(struct super_block *sb)
{
struct pts_fs_info *fsi;
fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
if (!fsi)
return NULL;
ida_init(&fsi->allocated_ptys);
fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
fsi->sb = sb;
return fsi;
}
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
struct inode *inode;
int error;
s->s_iflags &= ~SB_I_NODEV;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = DEVPTS_SUPER_MAGIC;
s->s_op = &devpts_sops;
s->s_time_gran = 1;
error = -ENOMEM;
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
s->s_fs_info = new_pts_fs_info(s);
if (!s->s_fs_info)
goto fail;
error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts);
if (error)
goto fail;
error = -ENOMEM;
inode = new_inode(s);
if (!inode)
goto fail;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
set_nlink(inode, 2);
s->s_root = d_make_root(inode);
if (!s->s_root) {
pr_err("get root dentry failed\n");
goto fail;
}
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
error = mknod_ptmx(s);
if (error)
goto fail_dput;
return 0;
fail_dput:
dput(s->s_root);
s->s_root = NULL;
fail:
return error;
}
Enable multiple instances of devpts To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:27 +03:00
/*
* devpts_mount()
*
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
* Mount a new (private) instance of devpts. PTYs created in this
* instance are independent of the PTYs in other devpts instances.
*/
static struct dentry *devpts_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return mount_nodev(fs_type, flags, data, devpts_fill_super);
}
static void devpts_kill_sb(struct super_block *sb)
{
struct pts_fs_info *fsi = DEVPTS_SB(sb);
if (fsi)
ida_destroy(&fsi->allocated_ptys);
kfree(fsi);
Define mknod_ptmx() /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 16:42:02 +03:00
kill_litter_super(sb);
}
static struct file_system_type devpts_fs_type = {
.name = "devpts",
.mount = devpts_mount,
.kill_sb = devpts_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
int devpts_new_index(struct pts_fs_info *fsi)
{
int index;
int ida_ret;
retry:
if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
return -ENOMEM;
mutex_lock(&allocated_ptys_lock);
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
if (pty_count >= (pty_limit -
(fsi->mount_opts.reserve ? 0 : pty_reserve))) {
mutex_unlock(&allocated_ptys_lock);
return -ENOSPC;
}
ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
if (ida_ret < 0) {
mutex_unlock(&allocated_ptys_lock);
if (ida_ret == -EAGAIN)
goto retry;
return -EIO;
}
if (index >= fsi->mount_opts.max) {
ida_remove(&fsi->allocated_ptys, index);
mutex_unlock(&allocated_ptys_lock);
return -ENOSPC;
}
pty_count++;
mutex_unlock(&allocated_ptys_lock);
return index;
}
devpts: clean up interface to pty drivers This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-17 01:16:07 +03:00
void devpts_kill_index(struct pts_fs_info *fsi, int idx)
{
mutex_lock(&allocated_ptys_lock);
ida_remove(&fsi->allocated_ptys, idx);
pty_count--;
mutex_unlock(&allocated_ptys_lock);
}
/**
* devpts_pty_new -- create a new inode in /dev/pts/
* @ptmx_inode: inode of the master
* @device: major+minor of the node to be created
* @index: used as a name of the node
* @priv: what's given back by devpts_get_priv
*
* The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill.
*/
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
{
struct dentry *dentry;
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
struct super_block *sb = fsi->sb;
struct inode *inode;
struct dentry *root;
struct pts_mount_opts *opts;
char s[12];
root = sb->s_root;
opts = &fsi->mount_opts;
inode = new_inode(sb);
if (!inode)
return ERR_PTR(-ENOMEM);
inode->i_ino = index + 3;
inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index));
sprintf(s, "%d", index);
dentry = d_alloc_name(root, s);
if (dentry) {
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
dentry->d_fsdata = priv;
d_add(dentry, inode);
fsnotify_create(d_inode(root), dentry);
} else {
iput(inode);
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
dentry = ERR_PTR(-ENOMEM);
}
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
return dentry;
}
/**
* devpts_get_priv -- get private data for a slave
* @pts_inode: inode of the slave
*
* Returns whatever was passed as priv in devpts_pty_new for a given inode.
*/
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
void *devpts_get_priv(struct dentry *dentry)
{
if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC)
return NULL;
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
return dentry->d_fsdata;
}
/**
* devpts_pty_kill -- remove inode form /dev/pts/
* @inode: inode of the slave to be removed
*
* This is an inverse operation of devpts_pty_new.
*/
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
void devpts_pty_kill(struct dentry *dentry)
{
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC);
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 06:04:08 +03:00
dentry->d_fsdata = NULL;
drop_nlink(dentry->d_inode);
d_delete(dentry);
dput(dentry); /* d_alloc_name() in devpts_pty_new() */
}
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts: Make each mount of devpts an independent filesystem. The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-02 18:29:47 +03:00
register_sysctl_table(pty_root_table);
}
return err;
}
module_init(init_devpts_fs)