* Patch "dcache: Handle escaped paths in prepend_path" has been added to the 4.2-stable tree
@ 2015-10-17 23:57 gregkh
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From: gregkh @ 2015-10-17 23:57 UTC (permalink / raw)
To: ebiederm, gregkh, viro; +Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
dcache: Handle escaped paths in prepend_path
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dcache-handle-escaped-paths-in-prepend_path.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From cde93be45a8a90d8c264c776fab63487b5038a65 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Sat, 15 Aug 2015 13:36:12 -0500
Subject: dcache: Handle escaped paths in prepend_path
From: "Eric W. Biederman" <ebiederm@xmission.com>
commit cde93be45a8a90d8c264c776fab63487b5038a65 upstream.
A rename can result in a dentry that by walking up d_parent
will never reach it's mnt_root. For lack of a better term
I call this an escaped path.
prepend_path is called by four different functions __d_path,
d_absolute_path, d_path, and getcwd.
__d_path only wants to see paths are connected to the root it passes
in. So __d_path needs prepend_path to return an error.
d_absolute_path similarly wants to see paths that are connected to
some root. Escaped paths are not connected to any mnt_root so
d_absolute_path needs prepend_path to return an error greater
than 1. So escaped paths will be treated like paths on lazily
unmounted mounts.
getcwd needs to prepend "(unreachable)" so getcwd also needs
prepend_path to return an error.
d_path is the interesting hold out. d_path just wants to print
something, and does not care about the weird cases. Which raises
the question what should be printed?
Given that <escaped_path>/<anything> should result in -ENOENT I
believe it is desirable for escaped paths to be printed as empty
paths. As there are not really any meaninful path components when
considered from the perspective of a mount tree.
So tweak prepend_path to return an empty path with an new error
code of 3 when it encounters an escaped path.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/dcache.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2926,6 +2926,13 @@ restart:
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
struct mount *parent = ACCESS_ONCE(mnt->mnt_parent);
+ /* Escaped? */
+ if (dentry != vfsmnt->mnt_root) {
+ bptr = *buffer;
+ blen = *buflen;
+ error = 3;
+ break;
+ }
/* Global root? */
if (mnt != parent) {
dentry = ACCESS_ONCE(mnt->mnt_mountpoint);
Patches currently in stable-queue which might be from ebiederm@xmission.com are
queue-4.2/dcache-handle-escaped-paths-in-prepend_path.patch
queue-4.2/vfs-test-for-and-handle-paths-that-are-unreachable-from-their-mnt_root.patch
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2015-10-17 23:57 Patch "dcache: Handle escaped paths in prepend_path" has been added to the 4.2-stable tree gregkh
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