From 62fa696b7b435e93ed114dd6a23aa0881d7f81b9 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 14 Dec 2016 13:24:50 +0100 Subject: posix_acl: Clear SGID bit when setting file permissions [ Upstream commit 073931017b49d9458aa351605b43a7e34598caef ] 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: Philipp Hahn Signed-off-by: Sasha Levin --- fs/hfsplus/posix_acl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/hfsplus') diff --git a/fs/hfsplus/posix_acl.c b/fs/hfsplus/posix_acl.c index df0c9af68d05..71b3087b7e32 100644 --- a/fs/hfsplus/posix_acl.c +++ b/fs/hfsplus/posix_acl.c @@ -68,8 +68,8 @@ int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl, case ACL_TYPE_ACCESS: xattr_name = POSIX_ACL_XATTR_ACCESS; if (acl) { - err = posix_acl_equiv_mode(acl, &inode->i_mode); - if (err < 0) + err = posix_acl_update_mode(inode, &inode->i_mode, &acl); + if (err) return err; } err = 0; -- cgit v1.2.3