Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755560Ab0GASLF (ORCPT ); Thu, 1 Jul 2010 14:11:05 -0400 Received: from kroah.org ([198.145.64.141]:60108 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755410Ab0GASK5 (ORCPT ); Thu, 1 Jul 2010 14:10:57 -0400 X-Mailbox-Line: From gregkh@clark.site Thu Jul 1 10:28:58 2010 Message-Id: <20100701172857.962093216@clark.site> User-Agent: quilt/0.48-10.1 Date: Thu, 01 Jul 2010 10:27:07 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Eugene Teo , Michael Kerrisk , Miklos Szeredi , Al Viro Subject: [18/23] vfs: add NOFOLLOW flag to umount(2) In-Reply-To: <20100701175134.GA2098@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2111 Lines: 63 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Miklos Szeredi commit db1f05bb85d7966b9176e293f3ceead1cb8b5d79 upstream. Add a new UMOUNT_NOFOLLOW flag to umount(2). This is needed to prevent symlink attacks in unprivileged unmounts (fuse, samba, ncpfs). Additionally, return -EINVAL if an unknown flag is used (and specify an explicitly unused flag: UMOUNT_UNUSED). This makes it possible for the caller to determine if a flag is supported or not. CC: Eugene Teo CC: Michael Kerrisk Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 9 ++++++++- include/linux/fs.h | 2 ++ 2 files changed, 10 insertions(+), 1 deletion(-) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1132,8 +1132,15 @@ SYSCALL_DEFINE2(umount, char __user *, n { struct path path; int retval; + int lookup_flags = 0; - retval = user_path(name, &path); + if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) + return -EINVAL; + + if (!(flags & UMOUNT_NOFOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + + retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); if (retval) goto out; retval = -EINVAL; --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1061,6 +1061,8 @@ extern int send_sigurg(struct fown_struc #define MNT_FORCE 0x00000001 /* Attempt to forcibily umount */ #define MNT_DETACH 0x00000002 /* Just detach from the tree */ #define MNT_EXPIRE 0x00000004 /* Mark for expiry */ +#define UMOUNT_NOFOLLOW 0x00000008 /* Don't follow symlink on umount */ +#define UMOUNT_UNUSED 0x80000000 /* Flag guaranteed to be unused */ extern struct list_head super_blocks; extern spinlock_t sb_lock; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/