[GITLAB] - A technical upgrade is planned on Thursday the 1st of July at noon on our GITLAB server.

Commit 91397d56 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Greg Kroah-Hartman

dcache: Handle escaped paths in prepend_path

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: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ef5844a0
......@@ -2534,6 +2534,8 @@ static int prepend_path(const struct path *path,
struct dentry *dentry = path->dentry;
struct vfsmount *vfsmnt = path->mnt;
struct mount *mnt = real_mount(vfsmnt);
char *orig_buffer = *buffer;
int orig_len = *buflen;
bool slash = false;
int error = 0;
......@@ -2541,6 +2543,14 @@ static int prepend_path(const struct path *path,
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
/* Escaped? */
if (dentry != vfsmnt->mnt_root) {
*buffer = orig_buffer;
*buflen = orig_len;
slash = false;
error = 3;
goto global_root;
/* Global root? */
if (!mnt_has_parent(mnt))
goto global_root;
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment