From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755727AbXD0MLc (ORCPT ); Fri, 27 Apr 2007 08:11:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755707AbXD0MLc (ORCPT ); Fri, 27 Apr 2007 08:11:32 -0400 Received: from mail-gw1.sa.eol.hu ([212.108.200.67]:54794 "EHLO mail-gw1.sa.eol.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755708AbXD0MLb (ORCPT ); Fri, 27 Apr 2007 08:11:31 -0400 Message-Id: <20070427120607.477677076@szeredi.hu> References: <20070427120417.110164241@szeredi.hu> User-Agent: quilt/0.45-1 Date: Fri, 27 Apr 2007 14:04:27 +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, kzak@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org Subject: [patch 10/10] unprivileged mounts: add "no submounts" flag Content-Disposition: inline; filename=unprivileged-mounts-add-no-submounts-flag.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi Add a new mount flag "nomnt", which denies submounts for the owner. This would be useful, if we want to support traditional /etc/fstab based user mounts. In this case mount(8) would still have to be suid-root, to check the mountpoint against the user/users flag in /etc/fstab, but /etc/mtab would no longer be mandatory for storing the actual owner of the mount. Signed-off-by: Miklos Szeredi --- Index: linux/fs/namespace.c =================================================================== --- linux.orig/fs/namespace.c 2007-04-27 12:57:11.000000000 +0200 +++ linux/fs/namespace.c 2007-04-27 12:57:14.000000000 +0200 @@ -449,6 +449,7 @@ static int show_vfsmnt(struct seq_file * { MNT_NOATIME, ",noatime" }, { MNT_NODIRATIME, ",nodiratime" }, { MNT_RELATIME, ",relatime" }, + { MNT_NOMNT, ",nomnt" }, { 0, NULL } }; struct proc_fs_info *fs_infop; @@ -806,6 +807,9 @@ static bool permit_mount(struct nameidat if (S_ISLNK(inode->i_mode)) return false; + if (nd->mnt->mnt_flags & MNT_NOMNT) + return false; + if (!is_mount_owner(nd->mnt, current->fsuid)) return false; @@ -1575,9 +1579,11 @@ long do_mount(char *dev_name, char *dir_ mnt_flags |= MNT_NODIRATIME; if (flags & MS_RELATIME) mnt_flags |= MNT_RELATIME; + if (flags & MS_NOMNT) + mnt_flags |= MNT_NOMNT; flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | - MS_NOATIME | MS_NODIRATIME | MS_RELATIME); + MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT); /* ... and get the mountpoint */ retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); Index: linux/include/linux/fs.h =================================================================== --- linux.orig/include/linux/fs.h 2007-04-27 12:57:11.000000000 +0200 +++ linux/include/linux/fs.h 2007-04-27 12:57:14.000000000 +0200 @@ -128,6 +128,7 @@ extern int dir_notify_enable; #define MS_SHARED (1<<20) /* change to shared */ #define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */ #define MS_SETUSER (1<<22) /* set mnt_uid to current user */ +#define MS_NOMNT (1<<23) /* don't allow unprivileged submounts */ #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) Index: linux/include/linux/mount.h =================================================================== --- linux.orig/include/linux/mount.h 2007-04-27 12:57:01.000000000 +0200 +++ linux/include/linux/mount.h 2007-04-27 12:57:14.000000000 +0200 @@ -28,6 +28,7 @@ struct mnt_namespace; #define MNT_NOATIME 0x08 #define MNT_NODIRATIME 0x10 #define MNT_RELATIME 0x20 +#define MNT_NOMNT 0x40 #define MNT_SHRINKABLE 0x100 #define MNT_USER 0x200 --