From patchwork Wed Nov 20 05:06:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aleksa Sarai X-Patchwork-Id: 11253065 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 675676C1 for ; Wed, 20 Nov 2019 05:08:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 52AE02240D for ; Wed, 20 Nov 2019 05:08:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726623AbfKTFIU (ORCPT ); Wed, 20 Nov 2019 00:08:20 -0500 Received: from mout-p-101.mailbox.org ([80.241.56.151]:11584 "EHLO mout-p-101.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726593AbfKTFIT (ORCPT ); Wed, 20 Nov 2019 00:08:19 -0500 Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:105:465:1:2:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mout-p-101.mailbox.org (Postfix) with ESMTPS id 47HrLT1YBxzKmgb; Wed, 20 Nov 2019 06:08:17 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id Ao3trqnTVvOG; Wed, 20 Nov 2019 06:08:14 +0100 (CET) From: Aleksa Sarai To: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , Jonathan Corbet Cc: Aleksa Sarai , "Eric W. Biederman" , Andy Lutomirski , Andrew Morton , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Rasmus Villemoes , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Christian Brauner , Aleksa Sarai , Linus Torvalds , dev@opencontainers.org, containers@lists.linux-foundation.org, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, libc-alpha@sourceware.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: [PATCH RESEND v17 01/13] namei: only return -ECHILD from follow_dotdot_rcu() Date: Wed, 20 Nov 2019 16:06:19 +1100 Message-Id: <20191120050631.12816-2-cyphar@cyphar.com> In-Reply-To: <20191120050631.12816-1-cyphar@cyphar.com> References: <20191120050631.12816-1-cyphar@cyphar.com> MIME-Version: 1.0 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org 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" Fixes: 397d425dc26d ("vfs: Test for and handle paths that are unreachable from their mnt_root") Suggested-by: Al Viro Signed-off-by: Aleksa Sarai --- 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; break; } else { struct mount *mnt = real_mount(nd->path.mnt);