The patch titled
Fix user.* xattr permission check for sticky dirs
has been added to the -mm tree. Its filename is
fix-user-xattr-permission-check-for-sticky-dirs.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix user.* xattr permission check for sticky dirs
From: Andreas Gruenbacher <agruen@xxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Andreas Gruenbacher <agruen@xxxxxxx>
Cc: Dave Kleikamp <shaggy@xxxxxxxxxxxxxx>
Cc: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/xattr.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff -puN fs/xattr.c~fix-user-xattr-permission-check-for-sticky-dirs fs/xattr.c
--- a/fs/xattr.c~fix-user-xattr-permission-check-for-sticky-dirs
+++ a/fs/xattr.c
@@ -48,14 +48,21 @@ xattr_permission(struct inode *inode, co
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;
}
_
Patches currently in -mm which might be from agruen@xxxxxxx are
fix-user-xattr-permission-check-for-sticky-dirs.patch
remove-superfluous-lock_super-in-ext2-and-ext3-xattr-code.patch
-
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