From: David Howells <dhowells@redhat.com>
To: viro@ZenIV.linux.org.uk
Cc: 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, David Howells <dhowells@redhat.com>
Subject: [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount
Date: Thu, 22 Jul 2010 18:59:13 +0100 [thread overview]
Message-ID: <20100722175913.5552.3905.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <20100722175847.5552.11520.stgit@warthog.procyon.org.uk>
Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of directories
with follow_link semantics. This can be used by fstatat()/xstat() 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 <dhowells@redhat.com>
---
fs/namei.c | 15 ++++++++++-----
fs/stat.c | 4 +++-
include/linux/fcntl.h | 1 +
include/linux/namei.h | 2 ++
4 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 86068a2..056427e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -654,7 +654,8 @@ static int follow_automount(struct path *path, int res)
/* no need for dcache_lock, as serialization is taken care in
* namespace.c
*/
-static int __follow_mount(struct path *path, unsigned nofollow)
+static int __follow_mount(struct path *path, unsigned nofollow,
+ struct nameidata *nd)
{
struct vfsmount *mounted;
int ret, res = 0;
@@ -674,8 +675,12 @@ static int __follow_mount(struct path *path, unsigned nofollow)
}
if (!d_automount_point(path->dentry))
break;
- if (nofollow)
- return -ELOOP;
+ if (!(nd->flags & LOOKUP_CONTINUE)) {
+ if (nofollow)
+ return -ELOOP;
+ if (nd->flags & LOOKUP_NO_AUTOMOUNT)
+ break;
+ }
ret = follow_automount(path, res);
if (ret < 0)
return ret;
@@ -769,7 +774,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
done:
path->mnt = mnt;
path->dentry = dentry;
- ret = __follow_mount(path, 0);
+ ret = __follow_mount(path, 0, nd);
if (unlikely(ret < 0))
path_put(path);
return ret;
@@ -1762,7 +1767,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
if (open_flag & O_EXCL)
goto exit_dput;
- error = __follow_mount(path, open_flag & O_NOFOLLOW);
+ error = __follow_mount(path, open_flag & O_NOFOLLOW, nd);
if (error < 0)
goto exit_dput;
diff --git a/fs/stat.c b/fs/stat.c
index c4ecd52..e4662de 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
*/
next prev parent reply other threads:[~2010-07-22 17:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-22 17:58 [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() David Howells
2010-07-22 17:58 ` David Howells
2010-07-22 17:58 ` [PATCH 2/6] AFS: Use d_automount() " David Howells
2010-07-22 17:59 ` [PATCH 5/6] Remove the automount through follow_link() kludge code from pathwalk David Howells
2010-07-22 17:59 ` David Howells [this message]
[not found] ` <20100722175847.5552.11520.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2010-07-22 17:58 ` [PATCH 3/6] NFS: Use d_automount() rather than abusing follow_link() David Howells
2010-07-22 17:58 ` David Howells
2010-07-22 17:59 ` [PATCH 4/6] CIFS: " David Howells
2010-07-22 17:59 ` David Howells
2010-07-23 15:09 ` [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() [ver #2] David Howells
2010-07-23 15:09 ` David Howells
[not found] ` <17723.1279897759-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-07-24 4:11 ` Ian Kent
2010-07-24 4:11 ` Ian Kent
2010-07-26 14:19 ` David Howells
[not found] ` <9168.1280153997-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-07-26 15:22 ` Ian Kent
2010-07-26 15:22 ` Ian Kent
2010-07-26 15:54 ` David Howells
[not found] ` <30118.1280159695-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-07-27 3:43 ` Ian Kent
2010-07-27 3:43 ` Ian Kent
2010-07-27 8:48 ` David Howells
[not found] ` <12883.1280220521-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-07-27 12:51 ` Ian Kent
2010-07-27 12:51 ` Ian Kent
[not found] ` <20100722175913.5552.3905.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2010-07-22 18:01 ` [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount David Howells
2010-07-22 18:01 ` David Howells
2010-07-23 15:11 ` [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount [ver #2] David Howells
2010-07-23 15:11 ` David Howells
2010-07-23 15:11 ` David Howells
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