diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2015-08-15 13:36:12 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-22 14:39:21 -0700 |
| commit | cb1320693b9d8d32651a2bb7cd15498408732b8f (patch) | |
| tree | e9444218d0ae4ef41609f3ecbd610f5c61a82074 | |
| parent | 0b39400f99f47ac8671c0956c480774b7f73804b (diff) | |
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: "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>
| -rw-r--r-- | fs/dcache.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index df323f809e03..65ccdf0e2854 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2787,6 +2787,13 @@ 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); |