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authorEric W. Biederman <ebiederm@xmission.com>2015-08-15 13:36:12 -0500
committerJiri Slaby <jslaby@suse.cz>2015-10-05 22:02:54 +0200
commitb32388c040d559d26feef31fa02b4119c76be474 (patch)
treec43cf94c1ce4651e2c918ca52d1016822082801b
parent864c198bbd4e091577602ad42016ccc835af3b93 (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: Jiri Slaby <jslaby@suse.cz>
-rw-r--r--fs/dcache.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 4c227f81051b..0fa3b3dba96f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2808,6 +2808,13 @@ restart:
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
+ /* Escaped? */
+ if (dentry != vfsmnt->mnt_root) {
+ bptr = *buffer;
+ blen = *buflen;
+ error = 3;
+ break;
+ }
/* Global root? */
if (mnt_has_parent(mnt)) {
dentry = mnt->mnt_mountpoint;