From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932181Ab0GWPLW (ORCPT ); Fri, 23 Jul 2010 11:11:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42636 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759985Ab0GWPLR (ORCPT ); Fri, 23 Jul 2010 11:11:17 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 In-Reply-To: <20100722175913.5552.3905.stgit@warthog.procyon.org.uk> References: <20100722175913.5552.3905.stgit@warthog.procyon.org.uk> <20100722175847.5552.11520.stgit@warthog.procyon.org.uk> To: viro@ZenIV.linux.org.uk Cc: dhowells@redhat.com, raven@themaw.net, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount [ver #2] Date: Fri, 23 Jul 2010 16:11:05 +0100 Message-ID: <17789.1279897865@redhat.com> From: David Howells Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an update required because the first patch in the series was also altered in the same area. David --- From: David Howells Subject: [PATCH] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of directories with follow_link semantics. This can be used by fstatat() users to permit the gathering of attributes on an automount point and also prevent mass-automounting of a directory of automount points by ls. Signed-off-by: David Howells --- fs/namei.c | 6 ++++++ fs/stat.c | 4 +++- include/linux/fcntl.h | 1 + include/linux/namei.h | 2 ++ 4 files changed, 12 insertions(+), 1 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index f2910b7..c154112 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -629,6 +629,12 @@ static int follow_automount(struct path *path, unsigned flags, int res) if (!path->dentry->d_op || !path->dentry->d_op->d_automount) return -EREMOTE; + /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT + * and this is the terminal part of the path. + */ + if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) + return -EXDEV; /* we actually want to stop here */ + /* We want to mount if someone is trying to open/create a file of any * type under the mountpoint, wants to traverse through the mountpoint * or wants to open the mounted directory. diff --git a/fs/stat.c b/fs/stat.c index c4ecd52..bae6fa2 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -74,11 +74,13 @@ int vfs_fstatat(int dfd, char __user *filename, struct kstat *stat, int flag) int error = -EINVAL; int lookup_flags = 0; - if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) + if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)) != 0) goto out; if (!(flag & AT_SYMLINK_NOFOLLOW)) lookup_flags |= LOOKUP_FOLLOW; + if (flag & AT_NO_AUTOMOUNT) + lookup_flags |= LOOKUP_NO_AUTOMOUNT; error = user_path_at(dfd, filename, lookup_flags, &path); if (error) diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index afc00af..a562fa5 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -45,6 +45,7 @@ #define AT_REMOVEDIR 0x200 /* Remove directory instead of unlinking file. */ #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */ +#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */ #ifdef __KERNEL__ diff --git a/include/linux/namei.h b/include/linux/namei.h index 05b441d..1e1febf 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -43,12 +43,14 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; * - internal "there are more path components" flag * - locked when lookup done with dcache_lock held * - dentry cache is untrusted; force a real lookup + * - suppress terminal automount */ #define LOOKUP_FOLLOW 1 #define LOOKUP_DIRECTORY 2 #define LOOKUP_CONTINUE 4 #define LOOKUP_PARENT 16 #define LOOKUP_REVAL 64 +#define LOOKUP_NO_AUTOMOUNT 128 /* * Intent data */