From 57c9cfdb61ea270936fab76da99a742c6ef0b86f Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 19 Sep 2016 17:39:09 +0200 Subject: posix_acl: Clear SGID bit when setting file permissions commit 073931017b49d9458aa351605b43a7e34598caef upstream. 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 Reviewed-by: Jeff Layton Signed-off-by: Jan Kara Signed-off-by: Andreas Gruenbacher Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_acl.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c index 6bb470fbb8e8..c5101a3295d8 100644 --- a/fs/xfs/xfs_acl.c +++ b/fs/xfs/xfs_acl.c @@ -288,16 +288,11 @@ 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; -- cgit v1.2.3