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[PATCH] Fix user.* xattr permission check for sticky dirs

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The user.* extended attributes are only allowed on regular files and
directories.  Sticky directories further restrict write access to the owner
and privileged users.  (See the attr(5) man page for an explanation.)

The original check in ext2/ext3 when user.* xattrs were merged was more
restrictive than intended, and when the xattr permission checks were moved
into the VFS, read access to user.* attributes on sticky directores ended
up being denied in addition.

Originally-from: Gerard Neil <xyzzy@devferret.org>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andreas Gruenbacher 2006-11-02 22:07:29 -08:00 committed by Linus Torvalds
parent 8ce08464d2
commit f1f2d8713d
1 changed files with 10 additions and 3 deletions
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13
fs/xattr.c
View file

@ -48,14 +48,21 @@ xattr_permission(struct inode *inode, const char *name, int mask)
return 0;
/*
* The trusted.* namespace can only accessed by a privilegued user.
* The trusted.* namespace can only be accessed by a privileged user.
*/
if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
/* In user.* namespace, only regular files and directories can have
* extended attributes. For sticky directories, only the owner and
* privileged user can write attributes.
*/
if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
if (!S_ISREG(inode->i_mode) &&
(!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
return -EPERM;
if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
(mask & MAY_WRITE) && (current->fsuid != inode->i_uid) &&
!capable(CAP_FOWNER))
return -EPERM;
}