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authorJan Kara <jack@suse.cz>2016-09-19 17:39:09 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-10-31 04:13:58 -0600
commit57c9cfdb61ea270936fab76da99a742c6ef0b86f (patch)
tree21d4a6c2d00f59986ddfdeaea80af4f760884ab3 /fs/btrfs
parentb82a7f93b4e60d8689d8f4e687ef58ed2098739f (diff)
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 <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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/acl.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 9a0124a95851..fb3e64d37cb4 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -83,11 +83,9 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
- ret = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (ret < 0)
+ ret = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (ret)
return ret;
- if (ret == 0)
- acl = NULL;
}
ret = 0;
break;