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authorJan Kara <jack@suse.cz>2016-09-19 17:39:09 +0200
committerJan Kara <jack@suse.cz>2016-09-22 10:55:32 +0200
commit073931017b49d9458aa351605b43a7e34598caef (patch)
tree8c4374e82e5cad92bdb589e5be417f1a94870399 /fs/xfs
parent5d3ddd84eaefffd23c028bce5610dac8726f71c1 (diff)
posix_acl: Clear SGID bit when setting file permissions
When file permissions are modified via chmod(2) and the user is not in the owning group or capable of CAP_FSETID, the setgid bit is cleared in inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file permissions as well as the new ACL, but doesn't clear the setgid bit in a similar way; this allows to bypass the check in chmod(2). Fix that. References: CVE-2016-7097 Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_acl.c13
1 files changed, 4 insertions, 9 deletions
diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index b6e527b8eccb..8a0dec89ca56 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -257,16 +257,11 @@ xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
return error;
if (type == ACL_TYPE_ACCESS) {
- umode_t mode = inode->i_mode;
- error = posix_acl_equiv_mode(acl, &mode);
-
- if (error <= 0) {
- acl = NULL;
-
- if (error < 0)
- return error;
- }
+ umode_t mode;
+ error = posix_acl_update_mode(inode, &mode, &acl);
+ if (error)
+ return error;
error = xfs_set_mode(inode, mode);
if (error)
return error;