From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 F1CACC43612 for ; Mon, 17 Dec 2018 15:56:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C964A2133F for ; Mon, 17 Dec 2018 15:56:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387766AbeLQP4s (ORCPT ); Mon, 17 Dec 2018 10:56:48 -0500 Received: from mxout3.mail.janestreet.com ([38.105.200.229]:55628 "EHLO mxout3.mail.janestreet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727833AbeLQP4r (ORCPT ); Mon, 17 Dec 2018 10:56:47 -0500 X-JS-Received: from [30.40.81.8] (helo=tot-qpr-mailcore1) by mxout3.mail.janestreet.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1gYvGA-0008MX-N9 for linux-nfs@vger.kernel.org; Mon, 17 Dec 2018 10:56:46 -0500 X-JS-Flow: external X-JS-Scanner-attachment: No attachments X-JS-Scanner-esets: Not scanned (internal mail) X-JS-Received: by tot-qpr-mailcore1 with ocaml/mailcore/main_production (71f307ccacc9) (envelope-from ) id BcF8c--M6jmcA-Rf; 2018-12-17 10:56:46.608495-05:00 X-JS-Received: by igm-qpr-mailgw2 with ocaml/mailcore/main_gateway (1e9cb192eda3) (envelope-from ) id BcF8c--M9XcgA-RK; 2018-12-17 10:56:46.551270-05:00 X-JS-Received: from cperl by igm-qws-u12114b.delacy.com with local (Exim 4.91) (envelope-from ) id 1gYvGA-00084c-Ga; Mon, 17 Dec 2018 10:56:46 -0500 From: Chris Perl To: linux-nfs@vger.kernel.org Cc: Chris Perl Subject: [PATCH V2 0/1] Fix incorrect sharing of AUTH_SYS and AUTH_GSS_KRB5 data structures Date: Mon, 17 Dec 2018 10:56:37 -0500 Message-Id: <20181217155638.30975-1-cperl@janestreet.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-JS-Region: Americas X-JS-Processed-by: mailcore Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org I've marked this as V2, even though it is really the same exact patch as last time. The only change is the addition of a Signed-off-by in the commit message. Original email below. Hi! I explained most of the details in the commit, but the gist is that mounts that don't have an explicit `sec' option passed will never get through the first part of the if statement I removed, meaning a mount which has its auth flavor discovered at mount time (e.g. in `nfs_try_mount_request') cannot pass that test. This means auth flavors are not compared and can lead to incorrect sharing of data structures via `nfs_fs_mount_common'. I am not the most familiar with all this code, so I might be missing something about why that check is needed. Please correct me if it needs to remain. In addition to testing this patch on a real system I tested something almost equivalent to this patch by using systemtap to force `b->auth_info.flavor_len' to 1 on every invocation if it was 0 (so the if would always succeed) and back to 0 on exit. Doing both of these things caused my issues to go away and helped to reinforce my notion that this was the right fix. In case you're interested, that script is below. Note that it hooks onto `nfs_compare_super' and not `nfs_compare_mount_options' because the latter is inlined. Please copy me directly on any replies, as I'm not a member of the list. global revert; probe module("nfs").function("nfs_compare_super").call { server = @cast($data, "struct nfs_sb_mountdata")->server; if (server->auth_info->flavor_len == 0) { server->auth_info->flavor_len = 1; revert = 1; } } probe module("nfs").function("nfs_compare_super").return { server = @cast($data, "struct nfs_sb_mountdata")->server; if (revert) { revert = 0; server->auth_info->flavor_len = 0; } } Chris Perl (1): NFS: nfs_compare_mount_options always compare auth flavors. fs/nfs/super.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) -- 2.17.1