From patchwork Tue Mar 3 17:43:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 229998 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7999FC3F2DA for ; Tue, 3 Mar 2020 17:57:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 502AC20656 for ; Tue, 3 Mar 2020 17:57:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583258229; bh=JZUiJW8eBhaeJc/jDJnUPBeA8VAv0ThULaayFwa2xhg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ACO31KnXLWexbavtMvvocFGLopxwIkxRJ8Z/U719N0LXzXCaDZsJntbos6Sq+HiQ0 e/2FfSg5yvOKUE2H4e1Ux5Xt413WV5kj0Er0juoaBBAaxwMOnTUOA9PPjFr83rCf15 WdjRU3EkPCiNVosyNMGROT/+RW+QA1+CVW5yGUdI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733008AbgCCR5H (ORCPT ); Tue, 3 Mar 2020 12:57:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:39426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732993AbgCCR5B (ORCPT ); Tue, 3 Mar 2020 12:57:01 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5AF3E206D5; Tue, 3 Mar 2020 17:57:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583258220; bh=JZUiJW8eBhaeJc/jDJnUPBeA8VAv0ThULaayFwa2xhg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LgglmpN5QvrF6t23BSD59nrTYF7EHqa7zjjigf8LbCR9hqhjamt/Ox+yJJX1dONQb a778UFbjhIcPugdgcPZx0EZvKovgvN0hziX3/OUvouXMwiiEybK4JytO5hCEf+Dqts dhp0bPyuL0OZCK+7mkOVKcAJ7A7eoZ/TFqrPHSss= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Eric W. Biederman" , Al Viro , Aleksa Sarai Subject: [PATCH 5.4 117/152] namei: only return -ECHILD from follow_dotdot_rcu() Date: Tue, 3 Mar 2020 18:43:35 +0100 Message-Id: <20200303174316.062304834@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200303174302.523080016@linuxfoundation.org> References: <20200303174302.523080016@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Aleksa Sarai 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" Fixes: 397d425dc26d ("vfs: Test for and handle paths that are unreachable from their mnt_root") Suggested-by: Al Viro Signed-off-by: Aleksa Sarai Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/namei.c +++ b/fs/namei.c @@ -1360,7 +1360,7 @@ 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);