Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761021AbYAHLkm (ORCPT ); Tue, 8 Jan 2008 06:40:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760340AbYAHLil (ORCPT ); Tue, 8 Jan 2008 06:38:41 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:51603 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760312AbYAHLij (ORCPT ); Tue, 8 Jan 2008 06:38:39 -0500 Message-Id: <20080108113634.382855604@szeredi.hu> References: <20080108113502.184459371@szeredi.hu> User-Agent: quilt/0.45-1 Date: Tue, 08 Jan 2008 12:35:11 +0100 From: Miklos Szeredi To: akpm@linux-foundation.org, hch@infradead.org, serue@us.ibm.com, viro@ftp.linux.org.uk, ebiederm@xmission.com, kzak@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org, util-linux-ng@vger.kernel.org Subject: [patch 9/9] unprivileged mounts: add "no submounts" flag Content-Disposition: inline; filename=unprivileged-mounts-add-no-submounts-flag.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3101 Lines: 81 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 2008-01-04 13:49:52.000000000 +0100 +++ linux/fs/namespace.c 2008-01-04 13:50:28.000000000 +0100 @@ -694,6 +694,7 @@ 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; @@ -1044,6 +1045,9 @@ static bool permit_mount(struct nameidat if (S_ISLNK(inode->i_mode)) return false; + if (nd->path.mnt->mnt_flags & MNT_NOMNT) + return false; + if (!is_mount_owner(nd->path.mnt, current->fsuid)) return false; @@ -1888,9 +1892,11 @@ long do_mount(char *dev_name, char *dir_ mnt_flags |= MNT_RELATIME; if (flags & MS_RDONLY) mnt_flags |= MNT_READONLY; + if (flags & MS_NOMNT) + mnt_flags |= MNT_NOMNT; - flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | - MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT); + flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_NOATIME | + MS_NODIRATIME | MS_RELATIME | MS_KERNMOUNT | 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 2008-01-04 13:49:12.000000000 +0100 +++ linux/include/linux/fs.h 2008-01-04 13:49:58.000000000 +0100 @@ -130,6 +130,7 @@ extern int dir_notify_enable; #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ #define MS_I_VERSION (1<<23) /* Update inode I_version field */ #define MS_SETUSER (1<<24) /* set mnt_uid to current user */ +#define MS_NOMNT (1<<25) /* 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 2008-01-04 13:45:45.000000000 +0100 +++ linux/include/linux/mount.h 2008-01-04 13:49:58.000000000 +0100 @@ -30,6 +30,7 @@ struct mnt_namespace; #define MNT_NODIRATIME 0x10 #define MNT_RELATIME 0x20 #define MNT_READONLY 0x40 /* does the user want this to be r/o? */ +#define MNT_NOMNT 0x80 #define MNT_SHRINKABLE 0x100 #define MNT_IMBALANCED_WRITE_COUNT 0x200 /* just for debugging */ -- -- 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/