| From 2b98149c2377bff12be5dd3ce02ae0506e2dd613 Mon Sep 17 00:00:00 2001 |
| From: Aleksa Sarai <cyphar@cyphar.com> |
| Date: Sat, 7 Dec 2019 01:13:26 +1100 |
| Subject: namei: only return -ECHILD from follow_dotdot_rcu() |
| |
| From: Aleksa Sarai <cyphar@cyphar.com> |
| |
| commit 2b98149c2377bff12be5dd3ce02ae0506e2dd613 upstream. |
| |
| 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 |
| RCU. |
| |
| 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> |
| Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/namei.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/fs/namei.c |
| +++ b/fs/namei.c |
| @@ -1367,7 +1367,7 @@ static int follow_dotdot_rcu(struct name |
| nd->path.dentry = parent; |
| nd->seq = seq; |
| if (unlikely(!path_connected(&nd->path))) |
| - return -ENOENT; |
| + return -ECHILD; |
| break; |
| } else { |
| struct mount *mnt = real_mount(nd->path.mnt); |
