From patchwork Tue May 5 08:32:06 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kinglong Mee X-Patchwork-Id: 6335851 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id DEC469F32E for ; Tue, 5 May 2015 08:33:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DAB2720328 for ; Tue, 5 May 2015 08:33:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A050A2034F for ; Tue, 5 May 2015 08:33:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756779AbbEEIdi (ORCPT ); Tue, 5 May 2015 04:33:38 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:34921 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756782AbbEEIdg (ORCPT ); Tue, 5 May 2015 04:33:36 -0400 Received: by pdbqd1 with SMTP id qd1so188674077pdb.2 for ; Tue, 05 May 2015 01:33:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=g6Tw7j+98wMzOzRW7Jyb+TU4Ary+Q6orwZ891JqNlms=; b=qnf3SdNIEJ4y8Kw6mj7zOueqWUDD6ksMQjyWt82qg8jUuDdB/EeoPbfta+hrcjYy2F QC7ncU0m6Knb9jg/iU1SgbeY5OZICAPSO/5Wnf970PC9VNarVJdaKy/5/vJefVGQnK92 6ByTC1vkiEFUz0PAMTFlg2BXUKxrfSEtPZf1Dc98u9SpRKyhSE1lw/pbzeJyQPI/+f9V qZcgHaHUegpiGV8qIWXJiiaJxphejGQKOyv93kTEI6aq6UUSzRF9iwIQFQwuh2JW78U7 /UNd+Espi1MS2zqOCZ2Y82131YbxBt6wX/2FM75R21ErrCE5620SSqpgNPB16dbVkqiz w2wg== X-Received: by 10.66.122.138 with SMTP id ls10mr2258265pab.63.1430814740346; Tue, 05 May 2015 01:32:20 -0700 (PDT) Received: from [192.168.99.3] ([104.143.41.79]) by mx.google.com with ESMTPSA id v6sm15145088pdj.26.2015.05.05.01.32.12 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 May 2015 01:32:18 -0700 (PDT) Message-ID: <55488006.6050502@gmail.com> Date: Tue, 05 May 2015 16:32:06 +0800 From: Kinglong Mee User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: NeilBrown CC: "J. Bruce Fields" , "linux-nfs@vger.kernel.org" , Al Viro , Steve Dickson , kinglongmee@gmail.com Subject: Re: [PATCH RFC] NFSD: fix cannot umounting mount points under pseudo root References: <20150421215417.GE13782@fieldses.org> <553781E2.1000900@gmail.com> <20150422150703.GA1247@fieldses.org> <20150423094431.1a8aa68b@notabene.brown> <5538EB18.7080802@gmail.com> <20150424130045.6bbdb2f9@notabene.brown> <553E2784.6020906@gmail.com> <20150429125728.69ddfc6c@notabene.brown> <20150429191934.GA23980@fieldses.org> <20150430075225.21a71056@notabene.brown> <20150430213602.GB9509@fieldses.org> <55483EB7.5060104@gmail.com> <20150505141957.2aef920e@notabene.brown> In-Reply-To: <20150505141957.2aef920e@notabene.brown> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, T_DKIM_INVALID, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 5/5/2015 12:19 PM, NeilBrown wrote: > On Tue, 05 May 2015 11:53:27 +0800 Kinglong Mee wrote: > >> Cc Steve, Viro, >> >> On 5/1/2015 5:36 AM, J. Bruce Fields wrote: >>> On Thu, Apr 30, 2015 at 07:52:25AM +1000, NeilBrown wrote: >>>> On Wed, 29 Apr 2015 15:19:34 -0400 "J. Bruce Fields" >>>> wrote: >>>>> Maybe drop the locking from nfsd_buffered_readdir and *just* take the >>>>> i_mutex around lookup_one_len(), if that's the only place we need it? >> >> As description in other thread, before the upcall to rpc.mountd, >> nfsd have call lookup_one_len() for the file, but why rpc.mountd >> also blocked in lookup ? >> >> There is a bug in rpc.mountd when checking sub-directory, >> it sets bad patch length for child. >> >> If parent if "/nfs/xfs" and child is "/nfs/test", the child name >> will be truncated to "/nfs/tes" for strlen(parent), "/nfs/test" >> have exist in kernel's cache for the lookup_one_len(), but >> "/nfs/tes" is a bad path, which needs lookup_slow(), so blocked. > > Testing for "/nfs/tes" certain seems like a wrong thing to do. > >> >> static int is_subdirectory(char *child, char *parent) >> { >> /* Check is child is strictly a subdirectory of >> * parent or a more distant descendant. >> */ >> size_t l = strlen(parent); >> >> if (strcmp(parent, "/") == 0 && child[1] != 0) >> return 1; >> >> return (same_path(child, parent, l) && child[l] == '/'); > > I guess this should be: > > child[l] == '/' && same_path(child, parent, l) > > That way there would be no risk of truncating anything. > > Can you please test if that one-line change removes the problem? Yes, that's OK. I have think about the "/nfs/nfs" and "/nfs/123" of the first patch, yes, that's redundant. > >> } >> >> The following path makes a correct path, not a truncated path. >> Have be tested, everything is OK. >> >> thanks, >> Kinglong Mee >> >> ----------------------------------------------------------------------------------- >> >From 70b9d1d93a24db8a7837998cb7eb0ff4e98480a6 Mon Sep 17 00:00:00 2001 >> From: Kinglong Mee >> Date: Tue, 5 May 2015 11:47:20 +0800 >> Subject: [PATCH] mountd: Case-insensitive path length must equal to parent >> >> Commit 6091c0a4c4 (mountd: add support for case-insensitive file names) >> introdues a bug cause mutex race when looking bad path. > > I think we should be clear that the mutex race is already present. > I think you are right that there is a bug here which is making it easy to > trigger, but it isn't exactly "causing" the bug. Thanks for the comments. thanks, Kinglong Mee ----------------------------------------------------------------------------------- From d831154bb7e527f9003e16ac049526be5ed90228 Mon Sep 17 00:00:00 2001 From: Kinglong Mee Date: Tue, 5 May 2015 16:24:16 +0800 Subject: [PATCH] mountd: Case-insensitive path length must equals to parent Commit 6091c0a4c4 (mountd: add support for case-insensitive file names) introduces looking up bad path which is easy to trigger a present mutex race. Signed-off-by: Kinglong Mee --- utils/mountd/cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c index 7d250f9..155695a 100644 --- a/utils/mountd/cache.c +++ b/utils/mountd/cache.c @@ -478,7 +478,7 @@ static int is_subdirectory(char *child, char *parent) if (strcmp(parent, "/") == 0 && child[1] != 0) return 1; - return (same_path(child, parent, l) && child[l] == '/'); + return (child[l] == '/' && same_path(child, parent, l)); } static int path_matches(nfs_export *exp, char *path)