From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753663AbXDPLGB (ORCPT ); Mon, 16 Apr 2007 07:06:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753089AbXDPLGA (ORCPT ); Mon, 16 Apr 2007 07:06:00 -0400 Received: from mail-gw2.sa.eol.hu ([212.108.200.109]:60167 "EHLO mail-gw2.sa.eol.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752389AbXDPLF4 (ORCPT ); Mon, 16 Apr 2007 07:05:56 -0400 Message-Id: <20070416110403.068601478@szeredi.hu> References: <20070416110308.739051445@szeredi.hu> User-Agent: quilt/0.45-1 Date: Mon, 16 Apr 2007 13:03:10 +0200 From: Miklos Szeredi To: akpm@linux-foundation.org, serue@us.ibm.com, viro@ftp.linux.org.uk, linuxram@us.ibm.com, ebiederm@xmission.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org Subject: [patch 02/10] allow unprivileged umount Content-Disposition: inline; filename=unprivileged_umount.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi The owner doesn't need sysadmin capabilities to call umount(). Similar behavior as umount(8) on mounts having "user=UID" option in /etc/mtab. The difference is that umount also checks /etc/fstab, presumably to exclude another mount on the same mountpoint. Signed-off-by: Miklos Szeredi --- Index: linux/fs/namespace.c =================================================================== --- linux.orig/fs/namespace.c 2007-04-11 20:07:51.000000000 +0200 +++ linux/fs/namespace.c 2007-04-11 20:08:05.000000000 +0200 @@ -659,6 +659,25 @@ static int do_umount(struct vfsmount *mn } /* + * umount is permitted for + * - sysadmin + * - mount owner, if not forced umount + */ +static bool permit_umount(struct vfsmount *mnt, int flags) +{ + if (capable(CAP_SYS_ADMIN)) + return true; + + if (!(mnt->mnt_flags & MNT_USER)) + return false; + + if (flags & MNT_FORCE) + return false; + + return mnt->mnt_uid == current->uid; +} + +/* * Now umount can handle mount points as well as block devices. * This is important for filesystems which use unnamed block devices. * @@ -681,7 +700,7 @@ asmlinkage long sys_umount(char __user * goto dput_and_out; retval = -EPERM; - if (!capable(CAP_SYS_ADMIN)) + if (!permit_umount(nd.mnt, flags)) goto dput_and_out; retval = do_umount(nd.mnt, flags); --