From: John@suse.de, Johansen@suse.de
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
Andreas Gruenbacher <agruen@suse.de>,
John Johansen <jjohansen@suse.de>
Subject: [AppArmor 30/47] Make d_path() consistent across mount operations
Date: Thu, 20 Dec 2007 06:09:40 -0800 [thread overview]
Message-ID: <20071220140946.068298016@suse.de> (raw)
In-Reply-To: 20071220140910.934607826@suse.de
[-- Attachment #1: mount-consistent-__d_path.diff --]
[-- Type: text/plain, Size: 1875 bytes --]
The path that __d_path() computes can become slightly inconsistent when it
races with mount operations: it grabs the vfsmount_lock when traversing mount
points but immediately drops it again, only to re-grab it when it reaches the
next mount point. The result is that the filename computed is not always
consisent, and the file may never have had that name. (This is unlikely, but
still possible.)
Fix this by grabbing the vfsmount_lock when the first mount point is reached,
and holding onto it until the d_cache lookup is completed.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: John Johansen <jjohansen@suse.de>
---
fs/dcache.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1766,7 +1766,7 @@ shouldnt_be_hashed:
static char *__d_path(struct path *path, struct path *root,
char *buffer, int buflen, int fail_deleted)
{
- int namelen, is_slash;
+ int namelen, is_slash, vfsmount_locked = 0;
struct dentry *dentry = path->dentry;
struct vfsmount *vfsmnt = path->mnt;
@@ -1791,14 +1791,14 @@ static char *__d_path(struct path *path,
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
- spin_lock(&vfsmount_lock);
- if (vfsmnt->mnt_parent == vfsmnt) {
- spin_unlock(&vfsmount_lock);
- goto global_root;
+ if (!vfsmount_locked) {
+ spin_lock(&vfsmount_lock);
+ vfsmount_locked = 1;
}
+ if (vfsmnt->mnt_parent == vfsmnt)
+ goto global_root;
dentry = vfsmnt->mnt_mountpoint;
vfsmnt = vfsmnt->mnt_parent;
- spin_unlock(&vfsmount_lock);
continue;
}
parent = dentry->d_parent;
@@ -1817,6 +1817,8 @@ static char *__d_path(struct path *path,
*--buffer = '/';
out:
+ if (vfsmount_locked)
+ spin_unlock(&vfsmount_lock);
spin_unlock(&dcache_lock);
return buffer;
--
next prev parent reply other threads:[~2007-12-20 14:26 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-20 14:09 [AppArmor 00/47] AppArmor security module overview John, Johansen
2007-12-20 14:09 ` [AppArmor 01/47] Pass struct vfsmount to the inode_create LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 02/47] Pass struct path down to remove_suid and children John, Johansen
2007-12-20 14:09 ` [AppArmor 03/47] Add a vfsmount parameter to notify_change() John, Johansen
2007-12-20 14:09 ` [AppArmor 04/47] Pass struct vfsmount to the inode_setattr LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 05/47] Add struct vfsmount parameter to vfs_mkdir() John, Johansen
2007-12-20 14:09 ` [AppArmor 06/47] Pass struct vfsmount to the inode_mkdir LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 07/47] Add a struct vfsmount parameter to vfs_mknod() John, Johansen
2007-12-20 14:09 ` [AppArmor 08/47] Pass struct vfsmount to the inode_mknod LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 09/47] Add a struct vfsmount parameter to vfs_symlink() John, Johansen
2007-12-20 14:09 ` [AppArmor 10/47] Pass struct vfsmount to the inode_symlink LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 11/47] Pass struct vfsmount to the inode_readlink " John, Johansen
2007-12-20 14:09 ` [AppArmor 12/47] Add struct vfsmount parameters to vfs_link() John, Johansen
2007-12-20 14:09 ` [AppArmor 13/47] Pass the struct vfsmounts to the inode_link LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 14/47] Add a struct vfsmount parameter to vfs_rmdir() John, Johansen
2007-12-20 14:09 ` [AppArmor 15/47] Pass struct vfsmount to the inode_rmdir LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 16/47] Call lsm hook before unhashing dentry in vfs_rmdir() John, Johansen
2007-12-20 14:09 ` [AppArmor 17/47] Add a struct vfsmount parameter to vfs_unlink() John, Johansen
2007-12-20 14:09 ` [AppArmor 18/47] Pass struct vfsmount to the inode_unlink LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 19/47] Add struct vfsmount parameters to vfs_rename() John, Johansen
2007-12-20 14:09 ` [AppArmor 20/47] Pass struct vfsmount to the inode_rename LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 21/47] Add a struct vfsmount parameter to vfs_setxattr() John, Johansen
2007-12-20 14:09 ` [AppArmor 22/47] Pass struct vfsmount to the inode_setxattr LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 23/47] Add a struct vfsmount parameter to vfs_getxattr() John, Johansen
2007-12-20 14:09 ` [AppArmor 24/47] Pass struct vfsmount to the inode_getxattr LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 25/47] Add a struct vfsmount parameter to vfs_listxattr() John, Johansen
2007-12-20 14:09 ` [AppArmor 26/47] Pass struct vfsmount to the inode_listxattr LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 27/47] Add a struct vfsmount parameter to vfs_removexattr() John, Johansen
2007-12-20 14:09 ` [AppArmor 28/47] Pass struct vfsmount to the inode_removexattr LSM hook John, Johansen
2007-12-20 14:09 ` [AppArmor 29/47] Fix __d_path() for lazy unmounts and make it unambiguous John, Johansen
2007-12-20 14:09 ` John, Johansen [this message]
2007-12-20 14:09 ` [AppArmor 31/47] Add d_namespace_path() to compute namespace relative pathnames John, Johansen
2007-12-20 14:09 ` [AppArmor 32/47] From: Miklos Szeredi <mszeredi@suse.cz> John, Johansen
2007-12-20 14:09 ` [AppArmor 33/47] VFS: new fsetattr() file operation John, Johansen
2007-12-20 14:09 ` [AppArmor 34/47] Pass struct file down the inode_*xattr security LSM hooks John, Johansen
2007-12-20 14:09 ` [AppArmor 35/47] Factor out sysctl pathname code John, Johansen
2007-12-20 14:09 ` [AppArmor 36/47] Allow permission functions to tell between parent and leaf checks John, Johansen
2007-12-20 14:09 ` [AppArmor 37/47] Switch to vfs_permission() in do_path_lookup() John, Johansen
2007-12-20 14:09 ` [AppArmor 38/47] Switch to vfs_permission() in sys_fchdir() John, Johansen
2007-12-20 14:09 ` [AppArmor 39/47] Fix file_permission() John, Johansen
2007-12-20 14:09 ` [AppArmor 40/47] Export audit subsystem for use by modules John, Johansen
2007-12-20 14:09 ` [AppArmor 41/47] AppArmor: Main Part John, Johansen
2007-12-20 14:09 ` [AppArmor 42/47] AppArmor: Module and LSM hooks John, Johansen
2007-12-20 14:09 ` [AppArmor 43/47] AppArmor: Profile loading and manipulation, pathname matching John, Johansen
2007-12-20 14:09 ` [AppArmor 44/47] AppArmor: all the rest John, Johansen
2007-12-20 14:09 ` [AppArmor 45/47] Add AppArmor LSM to security/Makefile John, Johansen
2007-12-20 14:09 ` [AppArmor 46/47] add simple network toggles to apparmor John, Johansen
2007-12-20 14:09 ` [AppArmor 47/47] --- Documentation/lsm/AppArmor-Security-Goal.txt | 134 +++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) John, Johansen
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