diff options
author | Eric W. Biederman <ebiederm@xmission.com> | 2015-08-15 13:36:12 -0500 |
---|---|---|
committer | Willy Tarreau <w@1wt.eu> | 2015-12-06 00:49:00 +0100 |
commit | fc9e08aac437c910e55f032a43bf70a22e5a038b (patch) | |
tree | 2892ef4ddd956c06aeb51b6c63a1edad232d3412 | |
parent | 6f493a57eac5fa655560c7a69f2aefa211927081 (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>
[bwh: For 2.6.32, implement the "(unreachable)" string in __d_path()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>
-rw-r--r-- | fs/dcache.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 44c0aeafcbc9..07c4472ca62c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1910,7 +1910,7 @@ char *__d_path(const struct path *path, struct path *root, struct dentry *dentry = path->dentry; struct vfsmount *vfsmnt = path->mnt; char *end = buffer + buflen; - char *retval; + char *retval, *tail; spin_lock(&vfsmount_lock); prepend(&end, &buflen, "\0", 1); @@ -1923,6 +1923,7 @@ char *__d_path(const struct path *path, struct path *root, /* Get '/' right */ retval = end-1; *retval = '/'; + tail = end; for (;;) { struct dentry * parent; @@ -1930,6 +1931,14 @@ char *__d_path(const struct path *path, struct path *root, if (dentry == root->dentry && vfsmnt == root->mnt) break; if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { + /* Escaped? */ + if (dentry != vfsmnt->mnt_root) { + buflen += (tail - end); + end = tail; + prepend(&end, &buflen, "(unreachable)/", 14); + retval = end; + goto out; + } /* Global root? */ if (vfsmnt->mnt_parent == vfsmnt) { goto global_root; |