[v18,01/13] namei: only return -ECHILD from follow_dotdot_rcu()

Message ID 20191206141338.23338-2-cyphar@cyphar.com
State New
Headers show
  • open: introduce openat2(2) syscall
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Commit Message

Aleksa Sarai Dec. 6, 2019, 2:13 p.m.
It's over-zealous to return hard errors under RCU-walk here, given that
a REF-walk will be triggered for all other cases handling ".." under

The original purpose of this check was to ensure that if a rename occurs
such that a directory is moved outside of the bind-mount which the
resolution started in, it would be detected and blocked to avoid being
able to mess with paths outside of the bind-mount. However, triggering a
new REF-walk is just as effective a solution.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Fixes: 397d425dc26d ("vfs: Test for and handle paths that are unreachable from their mnt_root")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

 fs/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)



diff --git a/fs/namei.c b/fs/namei.c
index 671c3c1a3425..5a47d9c09581 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1359,7 +1359,7 @@  static int follow_dotdot_rcu(struct nameidata *nd)
 			nd->path.dentry = parent;
 			nd->seq = seq;
 			if (unlikely(!path_connected(&nd->path)))
-				return -ENOENT;
+				return -ECHILD;
 		} else {
 			struct mount *mnt = real_mount(nd->path.mnt);