WSL2-Linux-Kernel/fs/namei.c

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69 KiB
C
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/*
* linux/fs/namei.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* Some corrections by tytso.
*/
/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
* lookup logic.
*/
/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/pagemap.h>
#include <linux/fsnotify.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/file.h>
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
#include <linux/fcntl.h>
cgroups: implement device whitelist Implement a cgroup to track and enforce open and mknod restrictions on device files. A device cgroup associates a device access whitelist with each cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or b (block). 'all' means it applies to all types and all major and minor numbers. Major and minor are either an integer or * for all. Access is a composition of r (read), w (write), and m (mknod). The root device cgroup starts with rwm to 'all'. A child devcg gets a copy of the parent. Admins can then remove devices from the whitelist or add new entries. A child cgroup can never receive a device access which is denied its parent. However when a device access is removed from a parent it will not also be removed from the child(ren). An entry is added using devices.allow, and removed using devices.deny. For instance echo 'c 1:3 mr' > /cgroups/1/devices.allow allows cgroup 1 to read and mknod the device usually known as /dev/null. Doing echo a > /cgroups/1/devices.deny will remove the default 'a *:* mrw' entry. CAP_SYS_ADMIN is needed to change permissions or move another task to a new cgroup. A cgroup may not be granted more permissions than the cgroup's parent has. Any task can move itself between cgroups. This won't be sufficient, but we can decide the best way to adequately restrict movement later. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix may-be-used-uninitialized warning] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: James Morris <jmorris@namei.org> Looks-good-to: Pavel Emelyanov <xemul@openvz.org> Cc: Daniel Hokka Zakrisson <daniel@hozac.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:00:10 +04:00
#include <linux/device_cgroup.h>
#include <asm/uaccess.h>
#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
/* [Feb-1997 T. Schoebel-Theuer]
* Fundamental changes in the pathname lookup mechanisms (namei)
* were necessary because of omirr. The reason is that omirr needs
* to know the _real_ pathname, not the user-supplied one, in case
* of symlinks (and also when transname replacements occur).
*
* The new code replaces the old recursive symlink resolution with
* an iterative one (in case of non-nested symlink chains). It does
* this with calls to <fs>_follow_link().
* As a side effect, dir_namei(), _namei() and follow_link() are now
* replaced with a single function lookup_dentry() that can handle all
* the special cases of the former code.
*
* With the new dcache, the pathname is stored at each inode, at least as
* long as the refcount of the inode is positive. As a side effect, the
* size of the dcache depends on the inode cache and thus is dynamic.
*
* [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
* resolution to correspond with current state of the code.
*
* Note that the symlink resolution is not *completely* iterative.
* There is still a significant amount of tail- and mid- recursion in
* the algorithm. Also, note that <fs>_readlink() is not used in
* lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
* may return different results than <fs>_follow_link(). Many virtual
* filesystems (including /proc) exhibit this behavior.
*/
/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
* New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
* and the name already exists in form of a symlink, try to create the new
* name indicated by the symlink. The old code always complained that the
* name already exists, due to not following the symlink even if its target
* is nonexistent. The new semantics affects also mknod() and link() when
* the name is a symlink pointing to a non-existant name.
*
* I don't know which semantics is the right one, since I have no access
* to standards. But I found by trial that HP-UX 9.0 has the full "new"
* semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
* "old" one. Personally, I think the new semantics is much more logical.
* Note that "ln old new" where "new" is a symlink pointing to a non-existing
* file does succeed in both HP-UX and SunOs, but not in Solaris
* and in the old Linux semantics.
*/
/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
* semantics. See the comments in "open_namei" and "do_link" below.
*
* [10-Sep-98 Alan Modra] Another symlink change.
*/
/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
* inside the path - always follow.
* in the last component in creation/removal/renaming - never follow.
* if LOOKUP_FOLLOW passed - follow.
* if the pathname has trailing slashes - follow.
* otherwise - don't follow.
* (applied in that order).
*
* [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
* restored for 2.4. This is the last surviving part of old 4.2BSD bug.
* During the 2.4 we need to fix the userland stuff depending on it -
* hopefully we will be able to get rid of that wart in 2.5. So far only
* XEmacs seems to be relying on it...
*/
/*
* [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
* implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
* any extra contention...
*/
static int __link_path_walk(const char *name, struct nameidata *nd);
/* In order to reduce some races, while at the same time doing additional
* checking and hopefully speeding things up, we copy filenames to the
* kernel data space before using them..
*
* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
* PATH_MAX includes the nul terminator --RR.
*/
static int do_getname(const char __user *filename, char *page)
{
int retval;
unsigned long len = PATH_MAX;
if (!segment_eq(get_fs(), KERNEL_DS)) {
if ((unsigned long) filename >= TASK_SIZE)
return -EFAULT;
if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
len = TASK_SIZE - (unsigned long) filename;
}
retval = strncpy_from_user(page, filename, len);
if (retval > 0) {
if (retval < len)
return 0;
return -ENAMETOOLONG;
} else if (!retval)
retval = -ENOENT;
return retval;
}
char * getname(const char __user * filename)
{
char *tmp, *result;
result = ERR_PTR(-ENOMEM);
tmp = __getname();
if (tmp) {
int retval = do_getname(filename, tmp);
result = tmp;
if (retval < 0) {
__putname(tmp);
result = ERR_PTR(retval);
}
}
audit_getname(result);
return result;
}
#ifdef CONFIG_AUDITSYSCALL
void putname(const char *name)
{
if (unlikely(!audit_dummy_context()))
audit_putname(name);
else
__putname(name);
}
EXPORT_SYMBOL(putname);
#endif
/**
* generic_permission - check for access rights on a Posix-like filesystem
* @inode: inode to check access rights for
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
* @check_acl: optional callback to check for Posix ACLs
*
* Used to check for read/write/execute permissions on a file.
* We use "fsuid" for this, letting us set arbitrary permissions
* for filesystem access without changing the "normal" uids which
* are used for other things..
*/
int generic_permission(struct inode *inode, int mask,
int (*check_acl)(struct inode *inode, int mask))
{
umode_t mode = inode->i_mode;
mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
if (current->fsuid == inode->i_uid)
mode >>= 6;
else {
if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
int error = check_acl(inode, mask);
if (error == -EACCES)
goto check_capabilities;
else if (error != -EAGAIN)
return error;
}
if (in_group_p(inode->i_gid))
mode >>= 3;
}
/*
* If the DACs are ok we don't need any capability check.
*/
if ((mask & ~mode) == 0)
return 0;
check_capabilities:
/*
* Read/write DACs are always overridable.
* Executable DACs are overridable if at least one exec bit is set.
*/
if (!(mask & MAY_EXEC) || execute_ok(inode))
if (capable(CAP_DAC_OVERRIDE))
return 0;
/*
* Searching includes executable on directories, else just read.
*/
if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
if (capable(CAP_DAC_READ_SEARCH))
return 0;
return -EACCES;
}
int inode_permission(struct inode *inode, int mask)
{
int retval;
if (mask & MAY_WRITE) {
umode_t mode = inode->i_mode;
/*
* Nobody gets write access to a read-only fs.
*/
if (IS_RDONLY(inode) &&
(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
return -EROFS;
/*
* Nobody gets write access to an immutable file.
*/
if (IS_IMMUTABLE(inode))
return -EACCES;
}
/* Ordinary permission routines do not understand MAY_APPEND. */
if (inode->i_op && inode->i_op->permission)
retval = inode->i_op->permission(inode, mask);
else
retval = generic_permission(inode, mask, NULL);
if (retval)
return retval;
cgroups: implement device whitelist Implement a cgroup to track and enforce open and mknod restrictions on device files. A device cgroup associates a device access whitelist with each cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or b (block). 'all' means it applies to all types and all major and minor numbers. Major and minor are either an integer or * for all. Access is a composition of r (read), w (write), and m (mknod). The root device cgroup starts with rwm to 'all'. A child devcg gets a copy of the parent. Admins can then remove devices from the whitelist or add new entries. A child cgroup can never receive a device access which is denied its parent. However when a device access is removed from a parent it will not also be removed from the child(ren). An entry is added using devices.allow, and removed using devices.deny. For instance echo 'c 1:3 mr' > /cgroups/1/devices.allow allows cgroup 1 to read and mknod the device usually known as /dev/null. Doing echo a > /cgroups/1/devices.deny will remove the default 'a *:* mrw' entry. CAP_SYS_ADMIN is needed to change permissions or move another task to a new cgroup. A cgroup may not be granted more permissions than the cgroup's parent has. Any task can move itself between cgroups. This won't be sufficient, but we can decide the best way to adequately restrict movement later. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix may-be-used-uninitialized warning] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: James Morris <jmorris@namei.org> Looks-good-to: Pavel Emelyanov <xemul@openvz.org> Cc: Daniel Hokka Zakrisson <daniel@hozac.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:00:10 +04:00
retval = devcgroup_inode_permission(inode, mask);
if (retval)
return retval;
return security_inode_permission(inode,
mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND));
}
/**
* vfs_permission - check for access rights to a given path
* @nd: lookup result that describes the path
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
* Used to check for read/write/execute permissions on a path.
* We use "fsuid" for this, letting us set arbitrary permissions
* for filesystem access without changing the "normal" uids which
* are used for other things.
*/
int vfs_permission(struct nameidata *nd, int mask)
{
return inode_permission(nd->path.dentry->d_inode, mask);
}
/**
* file_permission - check for additional access rights to a given file
* @file: file to check access rights for
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
* Used to check for read/write/execute permissions on an already opened
* file.
*
* Note:
* Do not use this function in new code. All access checks should
* be done using vfs_permission().
*/
int file_permission(struct file *file, int mask)
{
return inode_permission(file->f_path.dentry->d_inode, mask);
}
/*
* get_write_access() gets write permission for a file.
* put_write_access() releases this write permission.
* This is used for regular files.
* We cannot support write (and maybe mmap read-write shared) accesses and
* MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
* can have the following values:
* 0: no writers, no VM_DENYWRITE mappings
* < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
* > 0: (i_writecount) users are writing to the file.
*
* Normally we operate on that counter with atomic_{inc,dec} and it's safe
* except for the cases where we don't hold i_writecount yet. Then we need to
* use {get,deny}_write_access() - these functions check the sign and refuse
* to do the change if sign is wrong. Exclusion between them is provided by
* the inode->i_lock spinlock.
*/
int get_write_access(struct inode * inode)
{
spin_lock(&inode->i_lock);
if (atomic_read(&inode->i_writecount) < 0) {
spin_unlock(&inode->i_lock);
return -ETXTBSY;
}
atomic_inc(&inode->i_writecount);
spin_unlock(&inode->i_lock);
return 0;
}
int deny_write_access(struct file * file)
{
struct inode *inode = file->f_path.dentry->d_inode;
spin_lock(&inode->i_lock);
if (atomic_read(&inode->i_writecount) > 0) {
spin_unlock(&inode->i_lock);
return -ETXTBSY;
}
atomic_dec(&inode->i_writecount);
spin_unlock(&inode->i_lock);
return 0;
}
/**
* path_get - get a reference to a path
* @path: path to get the reference to
*
* Given a path increment the reference count to the dentry and the vfsmount.
*/
void path_get(struct path *path)
{
mntget(path->mnt);
dget(path->dentry);
}
EXPORT_SYMBOL(path_get);
/**
* path_put - put a reference to a path
* @path: path to put the reference to
*
* Given a path decrement the reference count to the dentry and the vfsmount.
*/
void path_put(struct path *path)
{
dput(path->dentry);
mntput(path->mnt);
}
EXPORT_SYMBOL(path_put);
/**
* release_open_intent - free up open intent resources
* @nd: pointer to nameidata
*/
void release_open_intent(struct nameidata *nd)
{
if (nd->intent.open.file->f_path.dentry == NULL)
put_filp(nd->intent.open.file);
else
fput(nd->intent.open.file);
}
static inline struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
int status = dentry->d_op->d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
/*
* The dentry failed validation.
* If d_revalidate returned 0 attempt to invalidate
* the dentry otherwise d_revalidate is asking us
* to return a fail status.
*/
if (!status) {
if (!d_invalidate(dentry)) {
dput(dentry);
dentry = NULL;
}
} else {
dput(dentry);
dentry = ERR_PTR(status);
}
}
return dentry;
}
/*
* Internal lookup() using the new generic dcache.
* SMP-safe
*/
static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
{
struct dentry * dentry = __d_lookup(parent, name);
/* lockess __d_lookup may fail due to concurrent d_move()
* in some unrelated directory, so try with d_lookup
*/
if (!dentry)
dentry = d_lookup(parent, name);
if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
dentry = do_revalidate(dentry, nd);
return dentry;
}
/*
* Short-cut version of permission(), for calling by
* path_walk(), when dcache lock is held. Combines parts
* of permission() and generic_permission(), and tests ONLY for
* MAY_EXEC permission.
*
* If appropriate, check DAC only. If not appropriate, or
* short-cut DAC fails, then call permission() to do more
* complete permission check.
*/
static int exec_permission_lite(struct inode *inode)
{
umode_t mode = inode->i_mode;
if (inode->i_op && inode->i_op->permission)
return -EAGAIN;
if (current->fsuid == inode->i_uid)
mode >>= 6;
else if (in_group_p(inode->i_gid))
mode >>= 3;
if (mode & MAY_EXEC)
goto ok;
if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
goto ok;
if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
goto ok;
if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
goto ok;
return -EACCES;
ok:
return security_inode_permission(inode, MAY_EXEC);
}
/*
* This is called when everything else fails, and we actually have
* to go to the low-level filesystem to find out what we should do..
*
* We get the directory semaphore, and after getting that we also
* make sure that nobody added the entry to the dcache in the meantime..
* SMP-safe
*/
static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
{
struct dentry * result;
struct inode *dir = parent->d_inode;
mutex_lock(&dir->i_mutex);
/*
* First re-do the cached lookup just in case it was created
* while we waited for the directory semaphore..
*
* FIXME! This could use version numbering or similar to
* avoid unnecessary cache lookups.
*
* The "dcache_lock" is purely to protect the RCU list walker
* from concurrent renames at this point (we mustn't get false
* negatives from the RCU list walk here, unlike the optimistic
* fast walk).
*
* so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
*/
result = d_lookup(parent, name);
if (!result) {
struct dentry *dentry;
/* Don't create child dentry for a dead directory. */
result = ERR_PTR(-ENOENT);
if (IS_DEADDIR(dir))
goto out_unlock;
dentry = d_alloc(parent, name);
result = ERR_PTR(-ENOMEM);
if (dentry) {
result = dir->i_op->lookup(dir, dentry, nd);
if (result)
dput(dentry);
else
result = dentry;
}
out_unlock:
mutex_unlock(&dir->i_mutex);
return result;
}
/*
* Uhhuh! Nasty case: the cache was re-populated while
* we waited on the semaphore. Need to revalidate.
*/
mutex_unlock(&dir->i_mutex);
if (result->d_op && result->d_op->d_revalidate) {
result = do_revalidate(result, nd);
if (!result)
result = ERR_PTR(-ENOENT);
}
return result;
}
/* SMP-safe */
static __always_inline void
walk_init_root(const char *name, struct nameidata *nd)
{
struct fs_struct *fs = current->fs;
read_lock(&fs->lock);
nd->path = fs->root;
path_get(&fs->root);
read_unlock(&fs->lock);
}
/*
* Wrapper to retry pathname resolution whenever the underlying
* file system returns an ESTALE.
*
* Retry the whole path once, forcing real lookup requests
* instead of relying on the dcache.
*/
static __always_inline int link_path_walk(const char *name, struct nameidata *nd)
{
struct path save = nd->path;
int result;
/* make sure the stuff we saved doesn't go away */
path_get(&save);
result = __link_path_walk(name, nd);
if (result == -ESTALE) {
/* nd->path had been dropped */
nd->path = save;
path_get(&nd->path);
nd->flags |= LOOKUP_REVAL;
result = __link_path_walk(name, nd);
}
path_put(&save);
return result;
}
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
{
int res = 0;
char *name;
if (IS_ERR(link))
goto fail;
if (*link == '/') {
path_put(&nd->path);
walk_init_root(link, nd);
}
res = link_path_walk(link, nd);
if (nd->depth || res || nd->last_type!=LAST_NORM)
return res;
/*
* If it is an iterative symlinks resolution in open_namei() we
* have to copy the last component. And all that crap because of
* bloody create() on broken symlinks. Furrfu...
*/
name = __getname();
if (unlikely(!name)) {
path_put(&nd->path);
return -ENOMEM;
}
strcpy(name, nd->last.name);
nd->last.name = name;
return 0;
fail:
path_put(&nd->path);
return PTR_ERR(link);
}
static void path_put_conditional(struct path *path, struct nameidata *nd)
{
dput(path->dentry);
if (path->mnt != nd->path.mnt)
mntput(path->mnt);
}
static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
{
dput(nd->path.dentry);
if (nd->path.mnt != path->mnt)
mntput(nd->path.mnt);
nd->path.mnt = path->mnt;
nd->path.dentry = path->dentry;
}
static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
{
int error;
void *cookie;
struct dentry *dentry = path->dentry;
touch_atime(path->mnt, dentry);
nd_set_link(nd, NULL);
if (path->mnt != nd->path.mnt) {
path_to_nameidata(path, nd);
dget(dentry);
}
mntget(path->mnt);
cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(cookie);
if (!IS_ERR(cookie)) {
char *s = nd_get_link(nd);
error = 0;
if (s)
error = __vfs_follow_link(nd, s);
if (dentry->d_inode->i_op->put_link)
dentry->d_inode->i_op->put_link(dentry, nd, cookie);
}
path_put(path);
return error;
}
/*
* This limits recursive symlink follows to 8, while
* limiting consecutive symlinks to 40.
*
* Without that kind of total limit, nasty chains of consecutive
* symlinks can cause almost arbitrarily long lookups.
*/
static inline int do_follow_link(struct path *path, struct nameidata *nd)
{
int err = -ELOOP;
if (current->link_count >= MAX_NESTED_LINKS)
goto loop;
if (current->total_link_count >= 40)
goto loop;
BUG_ON(nd->depth >= MAX_NESTED_LINKS);
cond_resched();
err = security_inode_follow_link(path->dentry, nd);
if (err)
goto loop;
current->link_count++;
current->total_link_count++;
nd->depth++;
err = __do_follow_link(path, nd);
current->link_count--;
nd->depth--;
return err;
loop:
path_put_conditional(path, nd);
path_put(&nd->path);
return err;
}
int follow_up(struct vfsmount **mnt, struct dentry **dentry)
{
struct vfsmount *parent;
struct dentry *mountpoint;
spin_lock(&vfsmount_lock);
parent=(*mnt)->mnt_parent;
if (parent == *mnt) {
spin_unlock(&vfsmount_lock);
return 0;
}
mntget(parent);
mountpoint=dget((*mnt)->mnt_mountpoint);
spin_unlock(&vfsmount_lock);
dput(*dentry);
*dentry = mountpoint;
mntput(*mnt);
*mnt = parent;
return 1;
}
/* no need for dcache_lock, as serialization is taken care in
* namespace.c
*/
static int __follow_mount(struct path *path)
{
int res = 0;
while (d_mountpoint(path->dentry)) {
struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
if (!mounted)
break;
dput(path->dentry);
if (res)
mntput(path->mnt);
path->mnt = mounted;
path->dentry = dget(mounted->mnt_root);
res = 1;
}
return res;
}
static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
{
while (d_mountpoint(*dentry)) {
struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
if (!mounted)
break;
dput(*dentry);
mntput(*mnt);
*mnt = mounted;
*dentry = dget(mounted->mnt_root);
}
}
/* no need for dcache_lock, as serialization is taken care in
* namespace.c
*/
int follow_down(struct vfsmount **mnt, struct dentry **dentry)
{
struct vfsmount *mounted;
mounted = lookup_mnt(*mnt, *dentry);
if (mounted) {
dput(*dentry);
mntput(*mnt);
*mnt = mounted;
*dentry = dget(mounted->mnt_root);
return 1;
}
return 0;
}
static __always_inline void follow_dotdot(struct nameidata *nd)
{
struct fs_struct *fs = current->fs;
while(1) {
struct vfsmount *parent;
struct dentry *old = nd->path.dentry;
read_lock(&fs->lock);
if (nd->path.dentry == fs->root.dentry &&
nd->path.mnt == fs->root.mnt) {
read_unlock(&fs->lock);
break;
}
read_unlock(&fs->lock);
spin_lock(&dcache_lock);
if (nd->path.dentry != nd->path.mnt->mnt_root) {
nd->path.dentry = dget(nd->path.dentry->d_parent);
spin_unlock(&dcache_lock);
dput(old);
break;
}
spin_unlock(&dcache_lock);
spin_lock(&vfsmount_lock);
parent = nd->path.mnt->mnt_parent;
if (parent == nd->path.mnt) {
spin_unlock(&vfsmount_lock);
break;
}
mntget(parent);
nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint);
spin_unlock(&vfsmount_lock);
dput(old);
mntput(nd->path.mnt);
nd->path.mnt = parent;
}
follow_mount(&nd->path.mnt, &nd->path.dentry);
}
/*
* It's more convoluted than I'd like it to be, but... it's still fairly
* small and for now I'd prefer to have fast path as straight as possible.
* It _is_ time-critical.
*/
static int do_lookup(struct nameidata *nd, struct qstr *name,
struct path *path)
{
struct vfsmount *mnt = nd->path.mnt;
struct dentry *dentry = __d_lookup(nd->path.dentry, name);
if (!dentry)
goto need_lookup;
if (dentry->d_op && dentry->d_op->d_revalidate)
goto need_revalidate;
done:
path->mnt = mnt;
path->dentry = dentry;
__follow_mount(path);
return 0;
need_lookup:
dentry = real_lookup(nd->path.dentry, name, nd);
if (IS_ERR(dentry))
goto fail;
goto done;
need_revalidate:
dentry = do_revalidate(dentry, nd);
if (!dentry)
goto need_lookup;
if (IS_ERR(dentry))
goto fail;
goto done;
fail:
return PTR_ERR(dentry);
}
/*
* Name resolution.
* This is the basic name resolution function, turning a pathname into
* the final dentry. We expect 'base' to be positive and a directory.
*
* Returns 0 and nd will have valid dentry and mnt on success.
* Returns error and drops reference to input namei data on failure.
*/
static int __link_path_walk(const char *name, struct nameidata *nd)
{
struct path next;
struct inode *inode;
int err;
unsigned int lookup_flags = nd->flags;
while (*name=='/')
name++;
if (!*name)
goto return_reval;
inode = nd->path.dentry->d_inode;
if (nd->depth)
lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
/* At this point we know we have a real path component. */
for(;;) {
unsigned long hash;
struct qstr this;
unsigned int c;
nd->flags |= LOOKUP_CONTINUE;
err = exec_permission_lite(inode);
if (err == -EAGAIN)
err = vfs_permission(nd, MAY_EXEC);
if (err)
break;
this.name = name;
c = *(const unsigned char *)name;
hash = init_name_hash();
do {
name++;
hash = partial_name_hash(c, hash);
c = *(const unsigned char *)name;
} while (c && (c != '/'));
this.len = name - (const char *) this.name;
this.hash = end_name_hash(hash);
/* remove trailing slashes? */
if (!c)
goto last_component;
while (*++name == '/');
if (!*name)
goto last_with_slashes;
/*
* "." and ".." are special - ".." especially so because it has
* to be able to know about the current root directory and
* parent relationships.
*/
if (this.name[0] == '.') switch (this.len) {
default:
break;
case 2:
if (this.name[1] != '.')
break;
follow_dotdot(nd);
inode = nd->path.dentry->d_inode;
/* fallthrough */
case 1:
continue;
}
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
&this);
if (err < 0)
break;
}
/* This does the actual lookups.. */
err = do_lookup(nd, &this, &next);
if (err)
break;
err = -ENOENT;
inode = next.dentry->d_inode;
if (!inode)
goto out_dput;
err = -ENOTDIR;
if (!inode->i_op)
goto out_dput;
if (inode->i_op->follow_link) {
err = do_follow_link(&next, nd);
if (err)
goto return_err;
err = -ENOENT;
inode = nd->path.dentry->d_inode;
if (!inode)
break;
err = -ENOTDIR;
if (!inode->i_op)
break;
} else
path_to_nameidata(&next, nd);
err = -ENOTDIR;
if (!inode->i_op->lookup)
break;
continue;
/* here ends the main loop */
last_with_slashes:
lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
last_component:
/* Clear LOOKUP_CONTINUE iff it was previously unset */
nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
if (lookup_flags & LOOKUP_PARENT)
goto lookup_parent;
if (this.name[0] == '.') switch (this.len) {
default:
break;
case 2:
if (this.name[1] != '.')
break;
follow_dotdot(nd);
inode = nd->path.dentry->d_inode;
/* fallthrough */
case 1:
goto return_reval;
}
if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
&this);
if (err < 0)
break;
}
err = do_lookup(nd, &this, &next);
if (err)
break;
inode = next.dentry->d_inode;
if ((lookup_flags & LOOKUP_FOLLOW)
&& inode && inode->i_op && inode->i_op->follow_link) {
err = do_follow_link(&next, nd);
if (err)
goto return_err;
inode = nd->path.dentry->d_inode;
} else
path_to_nameidata(&next, nd);
err = -ENOENT;
if (!inode)
break;
if (lookup_flags & LOOKUP_DIRECTORY) {
err = -ENOTDIR;
if (!inode->i_op || !inode->i_op->lookup)
break;
}
goto return_base;
lookup_parent:
nd->last = this;
nd->last_type = LAST_NORM;
if (this.name[0] != '.')
goto return_base;
if (this.len == 1)
nd->last_type = LAST_DOT;
else if (this.len == 2 && this.name[1] == '.')
nd->last_type = LAST_DOTDOT;
else
goto return_base;
return_reval:
/*
* We bypassed the ordinary revalidation routines.
* We may need to check the cached dentry for staleness.
*/
if (nd->path.dentry && nd->path.dentry->d_sb &&
(nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
err = -ESTALE;
/* Note: we do not d_invalidate() */
if (!nd->path.dentry->d_op->d_revalidate(
nd->path.dentry, nd))
break;
}
return_base:
return 0;
out_dput:
path_put_conditional(&next, nd);
break;
}
path_put(&nd->path);
return_err:
return err;
}
static int path_walk(const char *name, struct nameidata *nd)
{
current->total_link_count = 0;
return link_path_walk(name, nd);
}
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
static int do_path_lookup(int dfd, const char *name,
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
unsigned int flags, struct nameidata *nd)
{
int retval = 0;
int fput_needed;
struct file *file;
struct fs_struct *fs = current->fs;
nd->last_type = LAST_ROOT; /* if there are only slashes... */
nd->flags = flags;
nd->depth = 0;
if (*name=='/') {
read_lock(&fs->lock);
nd->path = fs->root;
path_get(&fs->root);
read_unlock(&fs->lock);
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
} else if (dfd == AT_FDCWD) {
read_lock(&fs->lock);
nd->path = fs->pwd;
path_get(&fs->pwd);
read_unlock(&fs->lock);
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
} else {
struct dentry *dentry;
file = fget_light(dfd, &fput_needed);
retval = -EBADF;
if (!file)
goto out_fail;
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
dentry = file->f_path.dentry;
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
retval = -ENOTDIR;
if (!S_ISDIR(dentry->d_inode->i_mode))
goto fput_fail;
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
retval = file_permission(file, MAY_EXEC);
if (retval)
goto fput_fail;
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
nd->path = file->f_path;
path_get(&file->f_path);
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
fput_light(file, fput_needed);
}
retval = path_walk(name, nd);
if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
nd->path.dentry->d_inode))
audit_inode(name, nd->path.dentry);
out_fail:
return retval;
fput_fail:
fput_light(file, fput_needed);
goto out_fail;
}
int path_lookup(const char *name, unsigned int flags,
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
struct nameidata *nd)
{
return do_path_lookup(AT_FDCWD, name, flags, nd);
}
int kern_path(const char *name, unsigned int flags, struct path *path)
{
struct nameidata nd;
int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
if (!res)
*path = nd.path;
return res;
}
fs: introduce vfs_path_lookup Stackable file systems, among others, frequently need to lookup paths or path components starting from an arbitrary point in the namespace (identified by a dentry and a vfsmount). Currently, such file systems use lookup_one_len, which is frowned upon [1] as it does not pass the lookup intent along; not passing a lookup intent, for example, can trigger BUG_ON's when stacking on top of NFSv4. The first patch introduces a new lookup function to allow lookup starting from an arbitrary point in the namespace. This approach has been suggested by Christoph Hellwig [2]. The second patch changes sunrpc to use vfs_path_lookup. The third patch changes nfsctl.c to use vfs_path_lookup. The fourth patch marks link_path_walk static. The fifth, and last patch, unexports path_walk because it is no longer unnecessary to call it directly, and using the new vfs_path_lookup is cleaner. For example, the following snippet of code, looks up "some/path/component" in a directory pointed to by parent_{dentry,vfsmnt}: err = vfs_path_lookup(parent_dentry, parent_vfsmnt, "some/path/component", 0, &nd); if (!err) { /* exits */ ... /* once done, release the references */ path_release(&nd); } else if (err == -ENOENT) { /* doesn't exist */ } else { /* other error */ } VFS functions such as lookup_create can be used on the nameidata structure to pass the create intent to the file system. Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@suse.de> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:48:18 +04:00
/**
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
* @dentry: pointer to dentry of the base directory
* @mnt: pointer to vfs mount of the base directory
* @name: pointer to file name
* @flags: lookup flags
* @nd: pointer to nameidata
*/
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
const char *name, unsigned int flags,
struct nameidata *nd)
{
int retval;
/* same as do_path_lookup */
nd->last_type = LAST_ROOT;
nd->flags = flags;
nd->depth = 0;
nd->path.dentry = dentry;
nd->path.mnt = mnt;
path_get(&nd->path);
fs: introduce vfs_path_lookup Stackable file systems, among others, frequently need to lookup paths or path components starting from an arbitrary point in the namespace (identified by a dentry and a vfsmount). Currently, such file systems use lookup_one_len, which is frowned upon [1] as it does not pass the lookup intent along; not passing a lookup intent, for example, can trigger BUG_ON's when stacking on top of NFSv4. The first patch introduces a new lookup function to allow lookup starting from an arbitrary point in the namespace. This approach has been suggested by Christoph Hellwig [2]. The second patch changes sunrpc to use vfs_path_lookup. The third patch changes nfsctl.c to use vfs_path_lookup. The fourth patch marks link_path_walk static. The fifth, and last patch, unexports path_walk because it is no longer unnecessary to call it directly, and using the new vfs_path_lookup is cleaner. For example, the following snippet of code, looks up "some/path/component" in a directory pointed to by parent_{dentry,vfsmnt}: err = vfs_path_lookup(parent_dentry, parent_vfsmnt, "some/path/component", 0, &nd); if (!err) { /* exits */ ... /* once done, release the references */ path_release(&nd); } else if (err == -ENOENT) { /* doesn't exist */ } else { /* other error */ } VFS functions such as lookup_create can be used on the nameidata structure to pass the create intent to the file system. Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@suse.de> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:48:18 +04:00
retval = path_walk(name, nd);
if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
nd->path.dentry->d_inode))
audit_inode(name, nd->path.dentry);
fs: introduce vfs_path_lookup Stackable file systems, among others, frequently need to lookup paths or path components starting from an arbitrary point in the namespace (identified by a dentry and a vfsmount). Currently, such file systems use lookup_one_len, which is frowned upon [1] as it does not pass the lookup intent along; not passing a lookup intent, for example, can trigger BUG_ON's when stacking on top of NFSv4. The first patch introduces a new lookup function to allow lookup starting from an arbitrary point in the namespace. This approach has been suggested by Christoph Hellwig [2]. The second patch changes sunrpc to use vfs_path_lookup. The third patch changes nfsctl.c to use vfs_path_lookup. The fourth patch marks link_path_walk static. The fifth, and last patch, unexports path_walk because it is no longer unnecessary to call it directly, and using the new vfs_path_lookup is cleaner. For example, the following snippet of code, looks up "some/path/component" in a directory pointed to by parent_{dentry,vfsmnt}: err = vfs_path_lookup(parent_dentry, parent_vfsmnt, "some/path/component", 0, &nd); if (!err) { /* exits */ ... /* once done, release the references */ path_release(&nd); } else if (err == -ENOENT) { /* doesn't exist */ } else { /* other error */ } VFS functions such as lookup_create can be used on the nameidata structure to pass the create intent to the file system. Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@suse.de> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:48:18 +04:00
return retval;
}
/**
* path_lookup_open - lookup a file path with open intent
* @dfd: the directory to use as base, or AT_FDCWD
* @name: pointer to file name
* @lookup_flags: lookup intent flags
* @nd: pointer to nameidata
* @open_flags: open intent flags
*/
int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
struct nameidata *nd, int open_flags)
{
struct file *filp = get_empty_filp();
int err;
if (filp == NULL)
return -ENFILE;
nd->intent.open.file = filp;
nd->intent.open.flags = open_flags;
nd->intent.open.create_mode = 0;
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
if (IS_ERR(nd->intent.open.file)) {
if (err == 0) {
err = PTR_ERR(nd->intent.open.file);
path_put(&nd->path);
}
} else if (err != 0)
release_open_intent(nd);
return err;
}
static struct dentry *__lookup_hash(struct qstr *name,
struct dentry *base, struct nameidata *nd)
{
struct dentry *dentry;
struct inode *inode;
int err;
inode = base->d_inode;
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
if (base->d_op && base->d_op->d_hash) {
err = base->d_op->d_hash(base, name);
dentry = ERR_PTR(err);
if (err < 0)
goto out;
}
dentry = cached_lookup(base, name, nd);
if (!dentry) {
struct dentry *new;
/* Don't create child dentry for a dead directory. */
dentry = ERR_PTR(-ENOENT);
if (IS_DEADDIR(inode))
goto out;
new = d_alloc(base, name);
dentry = ERR_PTR(-ENOMEM);
if (!new)
goto out;
dentry = inode->i_op->lookup(inode, new, nd);
if (!dentry)
dentry = new;
else
dput(new);
}
out:
return dentry;
}
/*
* Restricted form of lookup. Doesn't follow links, single-component only,
* needs parent already locked. Doesn't follow mounts.
* SMP-safe.
*/
static struct dentry *lookup_hash(struct nameidata *nd)
{
int err;
err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC);
if (err)
return ERR_PTR(err);
return __lookup_hash(&nd->last, nd->path.dentry, nd);
}
static int __lookup_one_len(const char *name, struct qstr *this,
struct dentry *base, int len)
{
unsigned long hash;
unsigned int c;
this->name = name;
this->len = len;
if (!len)
return -EACCES;
hash = init_name_hash();
while (len--) {
c = *(const unsigned char *)name++;
if (c == '/' || c == '\0')
return -EACCES;
hash = partial_name_hash(c, hash);
}
this->hash = end_name_hash(hash);
return 0;
}
/**
fs: fix kernel-doc notation warnings Fix kernel-doc notation warnings in fs/. Warning(mmotm-2008-0314-1449//fs/super.c:560): missing initial short description on line: * mark_files_ro Warning(mmotm-2008-0314-1449//fs/locks.c:1277): missing initial short description on line: * lease_get_mtime Warning(mmotm-2008-0314-1449//fs/locks.c:1277): missing initial short description on line: * lease_get_mtime Warning(mmotm-2008-0314-1449//fs/namei.c:1368): missing initial short description on line: * lookup_one_len: filesystem helper to lookup single pathname component Warning(mmotm-2008-0314-1449//fs/buffer.c:3221): missing initial short description on line: * bh_uptodate_or_lock: Test whether the buffer is uptodate Warning(mmotm-2008-0314-1449//fs/buffer.c:3240): missing initial short description on line: * bh_submit_read: Submit a locked buffer for reading Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:30): missing initial short description on line: * writeback_acquire: attempt to get exclusive writeback access to a device Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:47): missing initial short description on line: * writeback_in_progress: determine whether there is writeback in progress Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:58): missing initial short description on line: * writeback_release: relinquish exclusive writeback access against a device. Warning(mmotm-2008-0314-1449//include/linux/jbd.h:351): contents before sections Warning(mmotm-2008-0314-1449//include/linux/jbd.h:561): contents before sections Warning(mmotm-2008-0314-1449//fs/jbd/transaction.c:1935): missing initial short description on line: * void journal_invalidatepage() Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-20 03:01:00 +03:00
* lookup_one_len - filesystem helper to lookup single pathname component
* @name: pathname component to lookup
* @base: base directory to lookup from
* @len: maximum length @len should be interpreted to
*
fs: fix kernel-doc notation warnings Fix kernel-doc notation warnings in fs/. Warning(mmotm-2008-0314-1449//fs/super.c:560): missing initial short description on line: * mark_files_ro Warning(mmotm-2008-0314-1449//fs/locks.c:1277): missing initial short description on line: * lease_get_mtime Warning(mmotm-2008-0314-1449//fs/locks.c:1277): missing initial short description on line: * lease_get_mtime Warning(mmotm-2008-0314-1449//fs/namei.c:1368): missing initial short description on line: * lookup_one_len: filesystem helper to lookup single pathname component Warning(mmotm-2008-0314-1449//fs/buffer.c:3221): missing initial short description on line: * bh_uptodate_or_lock: Test whether the buffer is uptodate Warning(mmotm-2008-0314-1449//fs/buffer.c:3240): missing initial short description on line: * bh_submit_read: Submit a locked buffer for reading Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:30): missing initial short description on line: * writeback_acquire: attempt to get exclusive writeback access to a device Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:47): missing initial short description on line: * writeback_in_progress: determine whether there is writeback in progress Warning(mmotm-2008-0314-1449//fs/fs-writeback.c:58): missing initial short description on line: * writeback_release: relinquish exclusive writeback access against a device. Warning(mmotm-2008-0314-1449//include/linux/jbd.h:351): contents before sections Warning(mmotm-2008-0314-1449//include/linux/jbd.h:561): contents before sections Warning(mmotm-2008-0314-1449//fs/jbd/transaction.c:1935): missing initial short description on line: * void journal_invalidatepage() Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-20 03:01:00 +03:00
* Note that this routine is purely a helper for filesystem usage and should
* not be called by generic code. Also note that by using this function the
* nameidata argument is passed to the filesystem methods and a filesystem
* using this helper needs to be prepared for that.
*/
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
{
int err;
struct qstr this;
err = __lookup_one_len(name, &this, base, len);
if (err)
return ERR_PTR(err);
err = inode_permission(base->d_inode, MAY_EXEC);
if (err)
return ERR_PTR(err);
return __lookup_hash(&this, base, NULL);
}
/**
* lookup_one_noperm - bad hack for sysfs
* @name: pathname component to lookup
* @base: base directory to lookup from
*
* This is a variant of lookup_one_len that doesn't perform any permission
* checks. It's a horrible hack to work around the braindead sysfs
* architecture and should not be used anywhere else.
*
* DON'T USE THIS FUNCTION EVER, thanks.
*/
struct dentry *lookup_one_noperm(const char *name, struct dentry *base)
{
int err;
struct qstr this;
err = __lookup_one_len(name, &this, base, strlen(name));
if (err)
return ERR_PTR(err);
return __lookup_hash(&this, base, NULL);
}
int user_path_at(int dfd, const char __user *name, unsigned flags,
struct path *path)
{
struct nameidata nd;
char *tmp = getname(name);
int err = PTR_ERR(tmp);
if (!IS_ERR(tmp)) {
BUG_ON(flags & LOOKUP_PARENT);
err = do_path_lookup(dfd, tmp, flags, &nd);
putname(tmp);
if (!err)
*path = nd.path;
}
return err;
}
static int user_path_parent(int dfd, const char __user *path,
struct nameidata *nd, char **name)
{
char *s = getname(path);
int error;
if (IS_ERR(s))
return PTR_ERR(s);
error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
if (error)
putname(s);
else
*name = s;
return error;
}
/*
* It's inline, so penalty for filesystems that don't use sticky bit is
* minimal.
*/
static inline int check_sticky(struct inode *dir, struct inode *inode)
{
if (!(dir->i_mode & S_ISVTX))
return 0;
if (inode->i_uid == current->fsuid)
return 0;
if (dir->i_uid == current->fsuid)
return 0;
return !capable(CAP_FOWNER);
}
/*
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
* 1. We can't do it if dir is read-only (done in permission())
* 2. We should have write and exec permissions on dir
* 3. We can't remove anything from append-only dir
* 4. We can't do anything with immutable dir (done in permission())
* 5. If the sticky bit on dir is set we should either
* a. be owner of dir, or
* b. be owner of victim, or
* c. have CAP_FOWNER capability
* 6. If the victim is append-only or immutable we can't do antyhing with
* links pointing to it.
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
* 9. We can't remove a root or mountpoint.
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
{
int error;
if (!victim->d_inode)
return -ENOENT;
BUG_ON(victim->d_parent->d_inode != dir);
audit_inode_child(victim->d_name.name, victim, dir);
error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
if (error)
return error;
if (IS_APPEND(dir))
return -EPERM;
if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
IS_IMMUTABLE(victim->d_inode))
return -EPERM;
if (isdir) {
if (!S_ISDIR(victim->d_inode->i_mode))
return -ENOTDIR;
if (IS_ROOT(victim))
return -EBUSY;
} else if (S_ISDIR(victim->d_inode->i_mode))
return -EISDIR;
if (IS_DEADDIR(dir))
return -ENOENT;
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
return -EBUSY;
return 0;
}
/* Check whether we can create an object with dentry child in directory
* dir.
* 1. We can't do it if child already exists (open has special treatment for
* this case, but since we are inlined it's OK)
* 2. We can't do it if dir is read-only (done in permission())
* 3. We should have write and exec permissions on dir
* 4. We can't do it if dir is immutable (done in permission())
*/
static inline int may_create(struct inode *dir, struct dentry *child)
{
if (child->d_inode)
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
return inode_permission(dir, MAY_WRITE | MAY_EXEC);
}
/*
* O_DIRECTORY translates into forcing a directory lookup.
*/
static inline int lookup_flags(unsigned int f)
{
unsigned long retval = LOOKUP_FOLLOW;
if (f & O_NOFOLLOW)
retval &= ~LOOKUP_FOLLOW;
if (f & O_DIRECTORY)
retval |= LOOKUP_DIRECTORY;
return retval;
}
/*
* p1 and p2 should be directories on the same fs.
*/
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
{
struct dentry *p;
if (p1 == p2) {
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
return NULL;
}
mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
p = d_ancestor(p2, p1);
if (p) {
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
return p;
}
p = d_ancestor(p1, p2);
if (p) {
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
return p;
}
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
return NULL;
}
void unlock_rename(struct dentry *p1, struct dentry *p2)
{
mutex_unlock(&p1->d_inode->i_mutex);
if (p1 != p2) {
mutex_unlock(&p2->d_inode->i_mutex);
mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
}
}
int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
int error = may_create(dir, dentry);
if (error)
return error;
if (!dir->i_op || !dir->i_op->create)
return -EACCES; /* shouldn't it be ENOSYS? */
mode &= S_IALLUGO;
mode |= S_IFREG;
error = security_inode_create(dir, dentry, mode);
if (error)
return error;
DQUOT_INIT(dir);
error = dir->i_op->create(dir, dentry, mode, nd);
if (!error)
fsnotify_create(dir, dentry);
return error;
}
int may_open(struct nameidata *nd, int acc_mode, int flag)
{
struct dentry *dentry = nd->path.dentry;
struct inode *inode = dentry->d_inode;
int error;
if (!inode)
return -ENOENT;
if (S_ISLNK(inode->i_mode))
return -ELOOP;
if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE))
return -EISDIR;
/*
* FIFO's, sockets and device files are special: they don't
* actually live on the filesystem itself, and as such you
* can write to them even if the filesystem is read-only.
*/
if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
flag &= ~O_TRUNC;
} else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
if (nd->path.mnt->mnt_flags & MNT_NODEV)
return -EACCES;
flag &= ~O_TRUNC;
}
error = vfs_permission(nd, acc_mode);
if (error)
return error;
/*
* An append-only file must be opened in append mode for writing.
*/
if (IS_APPEND(inode)) {
if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
return -EPERM;
if (flag & O_TRUNC)
return -EPERM;
}
/* O_NOATIME can only be set by the owner or superuser */
if (flag & O_NOATIME)
if (!is_owner_or_cap(inode))
return -EPERM;
/*
* Ensure there are no outstanding leases on the file.
*/
error = break_lease(inode, flag);
if (error)
return error;
if (flag & O_TRUNC) {
error = get_write_access(inode);
if (error)
return error;
/*
* Refuse to truncate files with mandatory locks held on them.
*/
error = locks_verify_locked(inode);
if (!error) {
DQUOT_INIT(inode);
error = do_truncate(dentry, 0,
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
NULL);
}
put_write_access(inode);
if (error)
return error;
} else
if (flag & FMODE_WRITE)
DQUOT_INIT(inode);
return 0;
}
/*
* Be careful about ever adding any more callers of this
* function. Its flags must be in the namei format, not
* what get passed to sys_open().
*/
static int __open_namei_create(struct nameidata *nd, struct path *path,
int flag, int mode)
{
int error;
struct dentry *dir = nd->path.dentry;
if (!IS_POSIXACL(dir->d_inode))
mode &= ~current->fs->umask;
error = vfs_create(dir->d_inode, path->dentry, mode, nd);
mutex_unlock(&dir->d_inode->i_mutex);
dput(nd->path.dentry);
nd->path.dentry = path->dentry;
if (error)
return error;
/* Don't check for write permission, don't truncate */
return may_open(nd, 0, flag & ~O_TRUNC);
}
/*
* Note that while the flag value (low two bits) for sys_open means:
* 00 - read-only
* 01 - write-only
* 10 - read-write
* 11 - special
* it is changed into
* 00 - no permissions needed
* 01 - read-permission
* 10 - write-permission
* 11 - read-write
* for the internal routines (ie open_namei()/follow_link() etc)
* This is more logical, and also allows the 00 "no perm needed"
* to be used for symlinks (where the permissions are checked
* later).
*
*/
static inline int open_to_namei_flags(int flag)
{
if ((flag+1) & O_ACCMODE)
flag++;
return flag;
}
static int open_will_write_to_fs(int flag, struct inode *inode)
{
/*
* We'll never write to the fs underlying
* a device file.
*/
if (special_file(inode->i_mode))
return 0;
return (flag & O_TRUNC);
}
/*
* Note that the low bits of the passed in "open_flag"
* are not the same as in the local variable "flag". See
* open_to_namei_flags() for more details.
*/
struct file *do_filp_open(int dfd, const char *pathname,
int open_flag, int mode)
{
struct file *filp;
struct nameidata nd;
int acc_mode, error;
struct path path;
struct dentry *dir;
int count = 0;
int will_write;
int flag = open_to_namei_flags(open_flag);
acc_mode = MAY_OPEN | ACC_MODE(flag);
/* O_TRUNC implies we need access checks for write permissions */
if (flag & O_TRUNC)
acc_mode |= MAY_WRITE;
/* Allow the LSM permission hook to distinguish append
access from general write access. */
if (flag & O_APPEND)
acc_mode |= MAY_APPEND;
/*
* The simplest case - just a plain lookup.
*/
if (!(flag & O_CREAT)) {
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
error = path_lookup_open(dfd, pathname, lookup_flags(flag),
&nd, flag);
if (error)
return ERR_PTR(error);
goto ok;
}
/*
* Create - we need to know the parent.
*/
error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
if (error)
return ERR_PTR(error);
/*
* We have the parent and last component. First of all, check
* that we are not asked to creat(2) an obvious directory - that
* will not do.
*/
error = -EISDIR;
if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len])
goto exit_parent;
error = -ENFILE;
filp = get_empty_filp();
if (filp == NULL)
goto exit_parent;
nd.intent.open.file = filp;
nd.intent.open.flags = flag;
nd.intent.open.create_mode = mode;
dir = nd.path.dentry;
nd.flags &= ~LOOKUP_PARENT;
nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN;
if (flag & O_EXCL)
nd.flags |= LOOKUP_EXCL;
mutex_lock(&dir->d_inode->i_mutex);
path.dentry = lookup_hash(&nd);
path.mnt = nd.path.mnt;
do_last:
error = PTR_ERR(path.dentry);
if (IS_ERR(path.dentry)) {
mutex_unlock(&dir->d_inode->i_mutex);
goto exit;
}
if (IS_ERR(nd.intent.open.file)) {
error = PTR_ERR(nd.intent.open.file);
goto exit_mutex_unlock;
}
/* Negative dentry, just create the file */
if (!path.dentry->d_inode) {
/*
* This write is needed to ensure that a
* ro->rw transition does not occur between
* the time when the file is created and when
* a permanent write count is taken through
* the 'struct file' in nameidata_to_filp().
*/
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit_mutex_unlock;
error = __open_namei_create(&nd, &path, flag, mode);
if (error) {
mnt_drop_write(nd.path.mnt);
goto exit;
}
filp = nameidata_to_filp(&nd, open_flag);
mnt_drop_write(nd.path.mnt);
return filp;
}
/*
* It already exists.
*/
mutex_unlock(&dir->d_inode->i_mutex);
audit_inode(pathname, path.dentry);
error = -EEXIST;
if (flag & O_EXCL)
goto exit_dput;
if (__follow_mount(&path)) {
error = -ELOOP;
if (flag & O_NOFOLLOW)
goto exit_dput;
}
error = -ENOENT;
if (!path.dentry->d_inode)
goto exit_dput;
if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
goto do_link;
path_to_nameidata(&path, &nd);
error = -EISDIR;
if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
goto exit;
ok:
/*
* Consider:
* 1. may_open() truncates a file
* 2. a rw->ro mount transition occurs
* 3. nameidata_to_filp() fails due to
* the ro mount.
* That would be inconsistent, and should
* be avoided. Taking this mnt write here
* ensures that (2) can not occur.
*/
will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
if (will_write) {
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit;
}
error = may_open(&nd, acc_mode, flag);
if (error) {
if (will_write)
mnt_drop_write(nd.path.mnt);
goto exit;
}
filp = nameidata_to_filp(&nd, open_flag);
/*
* It is now safe to drop the mnt write
* because the filp has had a write taken
* on its behalf.
*/
if (will_write)
mnt_drop_write(nd.path.mnt);
return filp;
exit_mutex_unlock:
mutex_unlock(&dir->d_inode->i_mutex);
exit_dput:
path_put_conditional(&path, &nd);
exit:
if (!IS_ERR(nd.intent.open.file))
release_open_intent(&nd);
exit_parent:
path_put(&nd.path);
return ERR_PTR(error);
do_link:
error = -ELOOP;
if (flag & O_NOFOLLOW)
goto exit_dput;
/*
* This is subtle. Instead of calling do_follow_link() we do the
* thing by hands. The reason is that this way we have zero link_count
* and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
* After that we have the parent and last component, i.e.
* we are in the same situation as after the first path_walk().
* Well, almost - if the last component is normal we get its copy
* stored in nd->last.name and we will have to putname() it when we
* are done. Procfs-like symlinks just set LAST_BIND.
*/
nd.flags |= LOOKUP_PARENT;
error = security_inode_follow_link(path.dentry, &nd);
if (error)
goto exit_dput;
error = __do_follow_link(&path, &nd);
if (error) {
/* Does someone understand code flow here? Or it is only
* me so stupid? Anathema to whoever designed this non-sense
* with "intent.open".
*/
release_open_intent(&nd);
return ERR_PTR(error);
}
nd.flags &= ~LOOKUP_PARENT;
if (nd.last_type == LAST_BIND)
goto ok;
error = -EISDIR;
if (nd.last_type != LAST_NORM)
goto exit;
if (nd.last.name[nd.last.len]) {
__putname(nd.last.name);
goto exit;
}
error = -ELOOP;
if (count++==32) {
__putname(nd.last.name);
goto exit;
}
dir = nd.path.dentry;
mutex_lock(&dir->d_inode->i_mutex);
path.dentry = lookup_hash(&nd);
path.mnt = nd.path.mnt;
__putname(nd.last.name);
goto do_last;
}
/**
* filp_open - open file and return file pointer
*
* @filename: path to open
* @flags: open flags as per the open(2) second argument
* @mode: mode for the new file if O_CREAT is set, else ignored
*
* This is the helper to open a file from kernelspace if you really
* have to. But in generally you should not do this, so please move
* along, nothing to see here..
*/
struct file *filp_open(const char *filename, int flags, int mode)
{
return do_filp_open(AT_FDCWD, filename, flags, mode);
}
EXPORT_SYMBOL(filp_open);
/**
* lookup_create - lookup a dentry, creating it if it doesn't exist
* @nd: nameidata info
* @is_dir: directory flag
*
* Simple function to lookup and return a dentry and create it
* if it doesn't exist. Is SMP-safe.
*
* Returns with nd->path.dentry->d_inode->i_mutex locked.
*/
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
struct dentry *dentry = ERR_PTR(-EEXIST);
mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
/*
* Yucky last component or no last component at all?
* (foo/., foo/.., /////)
*/
if (nd->last_type != LAST_NORM)
goto fail;
nd->flags &= ~LOOKUP_PARENT;
nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
nd->intent.open.flags = O_EXCL;
/*
* Do the final lookup.
*/
dentry = lookup_hash(nd);
if (IS_ERR(dentry))
goto fail;
if (dentry->d_inode)
goto eexist;
/*
* Special case - lookup gave negative, but... we had foo/bar/
* From the vfs_mknod() POV we just have a negative dentry -
* all is fine. Let's be bastards - you had / on the end, you've
* been asking for (non-existent) directory. -ENOENT for you.
*/
if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
dput(dentry);
dentry = ERR_PTR(-ENOENT);
}
return dentry;
eexist:
dput(dentry);
dentry = ERR_PTR(-EEXIST);
fail:
return dentry;
}
EXPORT_SYMBOL_GPL(lookup_create);
int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
int error = may_create(dir, dentry);
if (error)
return error;
if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
return -EPERM;
if (!dir->i_op || !dir->i_op->mknod)
return -EPERM;
cgroups: implement device whitelist Implement a cgroup to track and enforce open and mknod restrictions on device files. A device cgroup associates a device access whitelist with each cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or b (block). 'all' means it applies to all types and all major and minor numbers. Major and minor are either an integer or * for all. Access is a composition of r (read), w (write), and m (mknod). The root device cgroup starts with rwm to 'all'. A child devcg gets a copy of the parent. Admins can then remove devices from the whitelist or add new entries. A child cgroup can never receive a device access which is denied its parent. However when a device access is removed from a parent it will not also be removed from the child(ren). An entry is added using devices.allow, and removed using devices.deny. For instance echo 'c 1:3 mr' > /cgroups/1/devices.allow allows cgroup 1 to read and mknod the device usually known as /dev/null. Doing echo a > /cgroups/1/devices.deny will remove the default 'a *:* mrw' entry. CAP_SYS_ADMIN is needed to change permissions or move another task to a new cgroup. A cgroup may not be granted more permissions than the cgroup's parent has. Any task can move itself between cgroups. This won't be sufficient, but we can decide the best way to adequately restrict movement later. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix may-be-used-uninitialized warning] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: James Morris <jmorris@namei.org> Looks-good-to: Pavel Emelyanov <xemul@openvz.org> Cc: Daniel Hokka Zakrisson <daniel@hozac.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 12:00:10 +04:00
error = devcgroup_inode_mknod(mode, dev);
if (error)
return error;
error = security_inode_mknod(dir, dentry, mode, dev);
if (error)
return error;
DQUOT_INIT(dir);
error = dir->i_op->mknod(dir, dentry, mode, dev);
if (!error)
fsnotify_create(dir, dentry);
return error;
}
static int may_mknod(mode_t mode)
{
switch (mode & S_IFMT) {
case S_IFREG:
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
case 0: /* zero mode translates to S_IFREG */
return 0;
case S_IFDIR:
return -EPERM;
default:
return -EINVAL;
}
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
unsigned dev)
{
int error;
char *tmp;
struct dentry *dentry;
struct nameidata nd;
if (S_ISDIR(mode))
return -EPERM;
error = user_path_parent(dfd, filename, &nd, &tmp);
if (error)
return error;
dentry = lookup_create(&nd, 0);
if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
goto out_unlock;
}
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
error = may_mknod(mode);
if (error)
goto out_dput;
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
break;
case S_IFCHR: case S_IFBLK:
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
new_decode_dev(dev));
break;
case S_IFIFO: case S_IFSOCK:
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
break;
}
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
putname(tmp);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev)
{
return sys_mknodat(AT_FDCWD, filename, mode, dev);
}
int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
int error = may_create(dir, dentry);
if (error)
return error;
if (!dir->i_op || !dir->i_op->mkdir)
return -EPERM;
mode &= (S_IRWXUGO|S_ISVTX);
error = security_inode_mkdir(dir, dentry, mode);
if (error)
return error;
DQUOT_INIT(dir);
error = dir->i_op->mkdir(dir, dentry, mode);
if (!error)
fsnotify_mkdir(dir, dentry);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
{
int error = 0;
char * tmp;
struct dentry *dentry;
struct nameidata nd;
error = user_path_parent(dfd, pathname, &nd, &tmp);
if (error)
goto out_err;
dentry = lookup_create(&nd, 1);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_unlock;
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
putname(tmp);
out_err:
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_mkdir(const char __user *pathname, int mode)
{
return sys_mkdirat(AT_FDCWD, pathname, mode);
}
/*
* We try to drop the dentry early: we should have
* a usage count of 2 if we're the only user of this
* dentry, and if that is true (possibly after pruning
* the dcache), then we drop the dentry now.
*
* A low-level filesystem can, if it choses, legally
* do a
*
* if (!d_unhashed(dentry))
* return -EBUSY;
*
* if it cannot handle the case of removing a directory
* that is still in use by something else..
*/
void dentry_unhash(struct dentry *dentry)
{
dget(dentry);
shrink_dcache_parent(dentry);
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
if (atomic_read(&dentry->d_count) == 2)
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
}
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
{
int error = may_delete(dir, dentry, 1);
if (error)
return error;
if (!dir->i_op || !dir->i_op->rmdir)
return -EPERM;
DQUOT_INIT(dir);
mutex_lock(&dentry->d_inode->i_mutex);
dentry_unhash(dentry);
if (d_mountpoint(dentry))
error = -EBUSY;
else {
error = security_inode_rmdir(dir, dentry);
if (!error) {
error = dir->i_op->rmdir(dir, dentry);
if (!error)
dentry->d_inode->i_flags |= S_DEAD;
}
}
mutex_unlock(&dentry->d_inode->i_mutex);
if (!error) {
d_delete(dentry);
}
dput(dentry);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
static long do_rmdir(int dfd, const char __user *pathname)
{
int error = 0;
char * name;
struct dentry *dentry;
struct nameidata nd;
error = user_path_parent(dfd, pathname, &nd, &name);
if (error)
return error;
switch(nd.last_type) {
case LAST_DOTDOT:
error = -ENOTEMPTY;
goto exit1;
case LAST_DOT:
error = -EINVAL;
goto exit1;
case LAST_ROOT:
error = -EBUSY;
goto exit1;
}
nd.flags &= ~LOOKUP_PARENT;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto exit2;
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit3;
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
mnt_drop_write(nd.path.mnt);
exit3:
dput(dentry);
exit2:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
exit1:
path_put(&nd.path);
putname(name);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_rmdir(const char __user *pathname)
{
return do_rmdir(AT_FDCWD, pathname);
}
int vfs_unlink(struct inode *dir, struct dentry *dentry)
{
int error = may_delete(dir, dentry, 0);
if (error)
return error;
if (!dir->i_op || !dir->i_op->unlink)
return -EPERM;
DQUOT_INIT(dir);
mutex_lock(&dentry->d_inode->i_mutex);
if (d_mountpoint(dentry))
error = -EBUSY;
else {
error = security_inode_unlink(dir, dentry);
if (!error)
error = dir->i_op->unlink(dir, dentry);
}
mutex_unlock(&dentry->d_inode->i_mutex);
/* We don't d_delete() NFS sillyrenamed files--they still exist. */
if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
fsnotify_link_count(dentry->d_inode);
d_delete(dentry);
}
return error;
}
/*
* Make sure that the actual truncation of the file will occur outside its
* directory's i_mutex. Truncate can take a long time if there is a lot of
* writeout happening, and we don't want to prevent access to the directory
* while waiting on the I/O.
*/
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
static long do_unlinkat(int dfd, const char __user *pathname)
{
int error;
char *name;
struct dentry *dentry;
struct nameidata nd;
struct inode *inode = NULL;
error = user_path_parent(dfd, pathname, &nd, &name);
if (error)
return error;
error = -EISDIR;
if (nd.last_type != LAST_NORM)
goto exit1;
nd.flags &= ~LOOKUP_PARENT;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
/* Why not before? Because we want correct error value */
if (nd.last.name[nd.last.len])
goto slashes;
inode = dentry->d_inode;
if (inode)
atomic_inc(&inode->i_count);
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit2;
error = vfs_unlink(nd.path.dentry->d_inode, dentry);
mnt_drop_write(nd.path.mnt);
exit2:
dput(dentry);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (inode)
iput(inode); /* truncate the inode here */
exit1:
path_put(&nd.path);
putname(name);
return error;
slashes:
error = !dentry->d_inode ? -ENOENT :
S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
goto exit2;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag)
{
if ((flag & ~AT_REMOVEDIR) != 0)
return -EINVAL;
if (flag & AT_REMOVEDIR)
return do_rmdir(dfd, pathname);
return do_unlinkat(dfd, pathname);
}
asmlinkage long sys_unlink(const char __user *pathname)
{
return do_unlinkat(AT_FDCWD, pathname);
}
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
{
int error = may_create(dir, dentry);
if (error)
return error;
if (!dir->i_op || !dir->i_op->symlink)
return -EPERM;
error = security_inode_symlink(dir, dentry, oldname);
if (error)
return error;
DQUOT_INIT(dir);
error = dir->i_op->symlink(dir, dentry, oldname);
if (!error)
fsnotify_create(dir, dentry);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_symlinkat(const char __user *oldname,
int newdfd, const char __user *newname)
{
int error;
char *from;
char *to;
struct dentry *dentry;
struct nameidata nd;
from = getname(oldname);
if (IS_ERR(from))
return PTR_ERR(from);
error = user_path_parent(newdfd, newname, &nd, &to);
if (error)
goto out_putname;
dentry = lookup_create(&nd, 0);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_unlock;
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
putname(to);
out_putname:
putname(from);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname)
{
return sys_symlinkat(oldname, AT_FDCWD, newname);
}
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
{
struct inode *inode = old_dentry->d_inode;
int error;
if (!inode)
return -ENOENT;
error = may_create(dir, new_dentry);
if (error)
return error;
if (dir->i_sb != inode->i_sb)
return -EXDEV;
/*
* A link to an append-only or immutable file cannot be created.
*/
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
return -EPERM;
if (!dir->i_op || !dir->i_op->link)
return -EPERM;
if (S_ISDIR(inode->i_mode))
return -EPERM;
error = security_inode_link(old_dentry, dir, new_dentry);
if (error)
return error;
mutex_lock(&inode->i_mutex);
DQUOT_INIT(dir);
error = dir->i_op->link(old_dentry, dir, new_dentry);
mutex_unlock(&inode->i_mutex);
if (!error)
fsnotify_link(dir, inode, new_dentry);
return error;
}
/*
* Hardlinks are often used in delicate situations. We avoid
* security-related surprises by not following symlinks on the
* newname. --KAB
*
* We don't follow them on the oldname either to be compatible
* with linux 2.0, and to avoid hard-linking to directories
* and other special files. --ADM
*/
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
int newdfd, const char __user *newname,
int flags)
{
struct dentry *new_dentry;
struct nameidata nd;
struct path old_path;
int error;
char *to;
if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
return -EINVAL;
error = user_path_at(olddfd, oldname,
flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
&old_path);
if (error)
return error;
error = user_path_parent(newdfd, newname, &nd, &to);
if (error)
goto out;
error = -EXDEV;
if (old_path.mnt != nd.path.mnt)
goto out_release;
new_dentry = lookup_create(&nd, 0);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto out_unlock;
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
mnt_drop_write(nd.path.mnt);
out_dput:
dput(new_dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
out_release:
path_put(&nd.path);
putname(to);
out:
path_put(&old_path);
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
{
return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
}
/*
* The worst of all namespace operations - renaming directory. "Perverted"
* doesn't even start to describe it. Somebody in UCB had a heck of a trip...
* Problems:
* a) we can get into loop creation. Check is done in is_subdir().
* b) race potential - two innocent renames can create a loop together.
* That's where 4.4 screws up. Current fix: serialization on
* sb->s_vfs_rename_mutex. We might be more accurate, but that's another
* story.
* c) we have to lock _three_ objects - parents and victim (if it exists).
* And that - after we got ->i_mutex on parents (until then we don't know
* whether the target exists). Solution: try to be smart with locking
* order for inodes. We rely on the fact that tree topology may change
* only under ->s_vfs_rename_mutex _and_ that parent of the object we
* move will be locked. Thus we can rank directories by the tree
* (ancestors first) and rank all non-directories after them.
* That works since everybody except rename does "lock parent, lookup,
* lock child" and rename is under ->s_vfs_rename_mutex.
* HOWEVER, it relies on the assumption that any object with ->lookup()
* has no more than 1 dentry. If "hybrid" objects will ever appear,
* we'd better make sure that there's no link(2) for them.
* d) some filesystems don't support opened-but-unlinked directories,
* either because of layout or because they are not ready to deal with
* all cases correctly. The latter will be fixed (taking this sort of
* stuff into VFS), but the former is not going away. Solution: the same
* trick as in rmdir().
* e) conversion from fhandle to dentry may come in the wrong moment - when
* we are removing the target. Solution: we will have to grab ->i_mutex
* in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
* ->i_mutex on parents, which works but leads to some truely excessive
* locking].
*/
static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
int error = 0;
struct inode *target;
/*
* If we are going to change the parent - check write permissions,
* we'll need to flip '..'.
*/
if (new_dir != old_dir) {
error = inode_permission(old_dentry->d_inode, MAY_WRITE);
if (error)
return error;
}
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
if (error)
return error;
target = new_dentry->d_inode;
if (target) {
mutex_lock(&target->i_mutex);
dentry_unhash(new_dentry);
}
if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
error = -EBUSY;
else
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
if (target) {
if (!error)
target->i_flags |= S_DEAD;
mutex_unlock(&target->i_mutex);
if (d_unhashed(new_dentry))
d_rehash(new_dentry);
dput(new_dentry);
}
if (!error)
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
d_move(old_dentry,new_dentry);
return error;
}
static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct inode *target;
int error;
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
if (error)
return error;
dget(new_dentry);
target = new_dentry->d_inode;
if (target)
mutex_lock(&target->i_mutex);
if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
error = -EBUSY;
else
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
if (!error) {
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
d_move(old_dentry, new_dentry);
}
if (target)
mutex_unlock(&target->i_mutex);
dput(new_dentry);
return error;
}
int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
int error;
int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
const char *old_name;
if (old_dentry->d_inode == new_dentry->d_inode)
return 0;
error = may_delete(old_dir, old_dentry, is_dir);
if (error)
return error;
if (!new_dentry->d_inode)
error = may_create(new_dir, new_dentry);
else
error = may_delete(new_dir, new_dentry, is_dir);
if (error)
return error;
if (!old_dir->i_op || !old_dir->i_op->rename)
return -EPERM;
DQUOT_INIT(old_dir);
DQUOT_INIT(new_dir);
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
if (is_dir)
error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
else
error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
if (!error) {
const char *new_name = old_dentry->d_name.name;
fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
new_dentry->d_inode, old_dentry);
}
fsnotify_oldname_free(old_name);
return error;
}
asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
int newdfd, const char __user *newname)
{
struct dentry *old_dir, *new_dir;
struct dentry *old_dentry, *new_dentry;
struct dentry *trap;
struct nameidata oldnd, newnd;
char *from;
char *to;
int error;
error = user_path_parent(olddfd, oldname, &oldnd, &from);
if (error)
goto exit;
error = user_path_parent(newdfd, newname, &newnd, &to);
if (error)
goto exit1;
error = -EXDEV;
if (oldnd.path.mnt != newnd.path.mnt)
goto exit2;
old_dir = oldnd.path.dentry;
error = -EBUSY;
if (oldnd.last_type != LAST_NORM)
goto exit2;
new_dir = newnd.path.dentry;
if (newnd.last_type != LAST_NORM)
goto exit2;
oldnd.flags &= ~LOOKUP_PARENT;
newnd.flags &= ~LOOKUP_PARENT;
newnd.flags |= LOOKUP_RENAME_TARGET;
trap = lock_rename(new_dir, old_dir);
old_dentry = lookup_hash(&oldnd);
error = PTR_ERR(old_dentry);
if (IS_ERR(old_dentry))
goto exit3;
/* source must exist */
error = -ENOENT;
if (!old_dentry->d_inode)
goto exit4;
/* unless the source is a directory trailing slashes give -ENOTDIR */
if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
error = -ENOTDIR;
if (oldnd.last.name[oldnd.last.len])
goto exit4;
if (newnd.last.name[newnd.last.len])
goto exit4;
}
/* source should not be ancestor of target */
error = -EINVAL;
if (old_dentry == trap)
goto exit4;
new_dentry = lookup_hash(&newnd);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto exit4;
/* target should not be an ancestor of source */
error = -ENOTEMPTY;
if (new_dentry == trap)
goto exit5;
error = mnt_want_write(oldnd.path.mnt);
if (error)
goto exit5;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
exit4:
dput(old_dentry);
exit3:
unlock_rename(new_dir, old_dir);
exit2:
path_put(&newnd.path);
putname(to);
exit1:
path_put(&oldnd.path);
putname(from);
exit:
return error;
}
[PATCH] vfs: *at functions: core Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-19 04:43:53 +03:00
asmlinkage long sys_rename(const char __user *oldname, const char __user *newname)
{
return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
}
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
{
int len;
len = PTR_ERR(link);
if (IS_ERR(link))
goto out;
len = strlen(link);
if (len > (unsigned) buflen)
len = buflen;
if (copy_to_user(buffer, link, len))
len = -EFAULT;
out:
return len;
}
/*
* A helper for ->readlink(). This should be used *ONLY* for symlinks that
* have ->follow_link() touching nd only in nd_set_link(). Using (or not
* using) it for any given inode is up to filesystem.
*/
int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
struct nameidata nd;
void *cookie;
int res;
nd.depth = 0;
cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
if (IS_ERR(cookie))
return PTR_ERR(cookie);
res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
if (dentry->d_inode->i_op->put_link)
dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
return res;
}
int vfs_follow_link(struct nameidata *nd, const char *link)
{
return __vfs_follow_link(nd, link);
}
/* get the link contents into pagecache */
static char *page_getlink(struct dentry * dentry, struct page **ppage)
{
struct page * page;
struct address_space *mapping = dentry->d_inode->i_mapping;
page = read_mapping_page(mapping, 0, NULL);
if (IS_ERR(page))
return (char*)page;
*ppage = page;
return kmap(page);
}
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
struct page *page = NULL;
char *s = page_getlink(dentry, &page);
int res = vfs_readlink(dentry,buffer,buflen,s);
if (page) {
kunmap(page);
page_cache_release(page);
}
return res;
}
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
{
struct page *page = NULL;
nd_set_link(nd, page_getlink(dentry, &page));
return page;
}
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
{
struct page *page = cookie;
if (page) {
kunmap(page);
page_cache_release(page);
}
}
int __page_symlink(struct inode *inode, const char *symname, int len,
gfp_t gfp_mask)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
void *fsdata;
int err;
char *kaddr;
retry:
err = pagecache_write_begin(NULL, mapping, 0, len-1,
AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
if (err)
goto fail;
kaddr = kmap_atomic(page, KM_USER0);
memcpy(kaddr, symname, len-1);
kunmap_atomic(kaddr, KM_USER0);
err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
page, fsdata);
if (err < 0)
goto fail;
if (err < len-1)
goto retry;
mark_inode_dirty(inode);
return 0;
fail:
return err;
}
int page_symlink(struct inode *inode, const char *symname, int len)
{
return __page_symlink(inode, symname, len,
mapping_gfp_mask(inode->i_mapping));
}
const struct inode_operations page_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = page_follow_link_light,
.put_link = page_put_link,
};
EXPORT_SYMBOL(user_path_at);
EXPORT_SYMBOL(follow_down);
EXPORT_SYMBOL(follow_up);
EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
EXPORT_SYMBOL(getname);
EXPORT_SYMBOL(lock_rename);
EXPORT_SYMBOL(lookup_one_len);
EXPORT_SYMBOL(page_follow_link_light);
EXPORT_SYMBOL(page_put_link);
EXPORT_SYMBOL(page_readlink);
EXPORT_SYMBOL(__page_symlink);
EXPORT_SYMBOL(page_symlink);
EXPORT_SYMBOL(page_symlink_inode_operations);
EXPORT_SYMBOL(path_lookup);
EXPORT_SYMBOL(kern_path);
fs: introduce vfs_path_lookup Stackable file systems, among others, frequently need to lookup paths or path components starting from an arbitrary point in the namespace (identified by a dentry and a vfsmount). Currently, such file systems use lookup_one_len, which is frowned upon [1] as it does not pass the lookup intent along; not passing a lookup intent, for example, can trigger BUG_ON's when stacking on top of NFSv4. The first patch introduces a new lookup function to allow lookup starting from an arbitrary point in the namespace. This approach has been suggested by Christoph Hellwig [2]. The second patch changes sunrpc to use vfs_path_lookup. The third patch changes nfsctl.c to use vfs_path_lookup. The fourth patch marks link_path_walk static. The fifth, and last patch, unexports path_walk because it is no longer unnecessary to call it directly, and using the new vfs_path_lookup is cleaner. For example, the following snippet of code, looks up "some/path/component" in a directory pointed to by parent_{dentry,vfsmnt}: err = vfs_path_lookup(parent_dentry, parent_vfsmnt, "some/path/component", 0, &nd); if (!err) { /* exits */ ... /* once done, release the references */ path_release(&nd); } else if (err == -ENOENT) { /* doesn't exist */ } else { /* other error */ } VFS functions such as lookup_create can be used on the nameidata structure to pass the create intent to the file system. Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@suse.de> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:48:18 +04:00
EXPORT_SYMBOL(vfs_path_lookup);
EXPORT_SYMBOL(inode_permission);
EXPORT_SYMBOL(vfs_permission);
EXPORT_SYMBOL(file_permission);
EXPORT_SYMBOL(unlock_rename);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_follow_link);
EXPORT_SYMBOL(vfs_link);
EXPORT_SYMBOL(vfs_mkdir);
EXPORT_SYMBOL(vfs_mknod);
EXPORT_SYMBOL(generic_permission);
EXPORT_SYMBOL(vfs_readlink);
EXPORT_SYMBOL(vfs_rename);
EXPORT_SYMBOL(vfs_rmdir);
EXPORT_SYMBOL(vfs_symlink);
EXPORT_SYMBOL(vfs_unlink);
EXPORT_SYMBOL(dentry_unhash);
EXPORT_SYMBOL(generic_readlink);