From patchwork Mon Aug 3 21:26:34 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 6933281 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 14081C05AC for ; Mon, 3 Aug 2015 21:33:21 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0BF42205BD for ; Mon, 3 Aug 2015 21:33:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E48E520383 for ; Mon, 3 Aug 2015 21:33:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932521AbbHCVdR (ORCPT ); Mon, 3 Aug 2015 17:33:17 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:35699 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932144AbbHCVdQ (ORCPT ); Mon, 3 Aug 2015 17:33:16 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZMNMB-00089j-Ss; Mon, 03 Aug 2015 15:33:15 -0600 Received: from 97-119-22-40.omah.qwest.net ([97.119.22.40] helo=x220.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZMNMA-0008TP-U5; Mon, 03 Aug 2015 15:33:15 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linux Containers Cc: , Al Viro , Andy Lutomirski , "Serge E. Hallyn" , Richard Weinberger , Andrey Vagin , Jann Horn , Willy Tarreau , Omar Sandoval , Miklos Szeredi , Linus Torvalds , "J. Bruce Fields" References: <871tncuaf6.fsf@x220.int.ebiederm.org> <87mw5xq7lt.fsf@x220.int.ebiederm.org> <87a8yqou41.fsf_-_@x220.int.ebiederm.org> <874moq9oyb.fsf_-_@x220.int.ebiederm.org> <871tfkawu9.fsf_-_@x220.int.ebiederm.org> Date: Mon, 03 Aug 2015 16:26:34 -0500 In-Reply-To: <871tfkawu9.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Mon, 03 Aug 2015 16:25:18 -0500") Message-ID: <87pp349i7p.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 X-XM-AID: U2FsdGVkX189wbi4C4l8OUeC+VqTFPwra5L93OH65QA= X-SA-Exim-Connect-IP: 97.119.22.40 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-DCC: XMission; sa04 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Linux Containers X-Spam-Relay-Country: X-Spam-Timing: total 493 ms - load_scoreonly_sql: 0.08 (0.0%), signal_user_changed: 12 (2.5%), b_tie_ro: 10 (2.1%), parse: 1.42 (0.3%), extract_message_metadata: 14 (2.9%), get_uri_detail_list: 1.77 (0.4%), tests_pri_-1000: 6 (1.2%), tests_pri_-950: 1.25 (0.3%), tests_pri_-900: 1.02 (0.2%), tests_pri_-400: 26 (5.2%), check_bayes: 24 (4.9%), b_tokenize: 7 (1.4%), b_tok_get_all: 8 (1.6%), b_comp_prob: 3.5 (0.7%), b_tok_touch_all: 3.3 (0.7%), b_finish: 0.96 (0.2%), tests_pri_0: 423 (85.9%), tests_pri_500: 4.2 (0.8%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH review 2/6] dcache: Handle escaped paths in prepend_path X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 / 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" --- fs/dcache.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index 5c8ea15e73a5..d7fe995dd32d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2926,6 +2926,13 @@ restart: if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); + /* Escaped? */ + if (dentry != vfsmnt->mnt_root) { + bptr = *buffer; + blen = *buflen; + error = 3; + break; + } /* Global root? */ if (mnt != parent) { dentry = ACCESS_ONCE(mnt->mnt_mountpoint);