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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 59250C433DF for ; Tue, 7 Jul 2020 18:31:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39E4C206F6 for ; Tue, 7 Jul 2020 18:31:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="Ftjs5t0I"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="jSA47Ed+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728284AbgGGSbj (ORCPT ); Tue, 7 Jul 2020 14:31:39 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:4278 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728036AbgGGSbi (ORCPT ); Tue, 7 Jul 2020 14:31:38 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 067IBJAs016027; Tue, 7 Jul 2020 11:31:32 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=date : from : to : cc : subject : message-id : references : content-type : in-reply-to : mime-version; s=facebook; bh=90H3+ChY0Rwj9+GuMXrRF8IMJEKjvLxb/I8QKWGBqw4=; b=Ftjs5t0IzmrcVbTAwk4DneghWV5rVAMR62hXAfF5G5PwpipoGi2wfW+nd4nTxLDD6bs9 GGZDDjuBG724Qz/jbHRlTcUC9UiOJlXcKH8olhn9MCZ0MiEB2hwEg8BDiLRTNS3nFTul ilP9s+ZaNAy0nGJEnFegUXfq2ZDX/fFGMlU= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 323a1nk3dw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 07 Jul 2020 11:31:32 -0700 Received: from NAM04-BN3-obe.outbound.protection.outlook.com (100.104.98.9) by o365-in.thefacebook.com (100.104.94.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 7 Jul 2020 11:31:31 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=WqG9sNPMhVIZHVq2qZ8a+HvLfGiC6bIPNG41fTmF2p6yjS8oqkbep5X7YpVaviDrDeIe7ePp4uKdYCWH8Fv0GYzX08VWGBpEmt3m9rQvYTThCNMHIeJhX9sZpE4zLaLpBZnFvMENSN8vhI3YMHrYz0P/zCMXVA7xRFwttUI9RFUZsKwgb/PiHrAibZIZHvi90dartLRzMPUt8K519iGDHykQqLpfPU+iEByXuefTbwojpO/yypbULt+Wm9FDpvf7/N/cDuZjZDReNBQ3IkbFjFbzS1S+3JW0gj7hKPlNdHREM9Llbm0Qf/7anv9rvmnp3Gesx28Ugl0g0jr+O1V+2A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=90H3+ChY0Rwj9+GuMXrRF8IMJEKjvLxb/I8QKWGBqw4=; b=lJP3kQk0wJzq9aW8a4dGwT7e+HZnEmSPwIXffEtvSs/dUA1ai/7sqpd/Njib6+LfQqdvDjPg1ok1aOMIgnCW2k4jNms9OrRjakzhxJusrZMgHJRoPZ53y2UZHhWey59neuThqDghs5lf13WY+0bq7rNxwSnOr1/SU2PMgu+rh/REXp6G2j160rv3bSIl0zIInWqOG1bwQWvw0SwEThdiGuIlRC627vovSaTmcymZVpGu7PIrzCEsN7KiUptaHYHGKX8wKXSf21gCx2WIZQ0SSwKW9WULQq9p4vfYm8oGzhLkEkJvx8LoPsBqAKgVem/h7+VQDR7En8zhIBMrAa4jIw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=90H3+ChY0Rwj9+GuMXrRF8IMJEKjvLxb/I8QKWGBqw4=; b=jSA47Ed+iXvg3z4RJ1A7EkgmElPMkcPWrLXc3MejYkaSeIbNAmHbPZP/ISDycH+mjGnuJK39vQIsdNMkQ497/mdPDRvjLqO/SacJ0cs+pt/HAHbugOtpjwdHvS8yZ388i3MxI+X7JBKJC1AXltQZQ+Y2ADYtCvLqCtotn6XwinM= Authentication-Results: katalix.com; dkim=none (message not signed) header.d=none;katalix.com; dmarc=none action=none header.from=fb.com; Received: from BY5PR15MB3571.namprd15.prod.outlook.com (2603:10b6:a03:1f6::32) by BYAPR15MB2824.namprd15.prod.outlook.com (2603:10b6:a03:158::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3153.27; Tue, 7 Jul 2020 18:31:30 +0000 Received: from BY5PR15MB3571.namprd15.prod.outlook.com ([fe80::d489:8f7f:614e:1b99]) by BY5PR15MB3571.namprd15.prod.outlook.com ([fe80::d489:8f7f:614e:1b99%7]) with mapi id 15.20.3153.029; Tue, 7 Jul 2020 18:31:29 +0000 Date: Tue, 7 Jul 2020 11:31:28 -0700 From: Martin KaFai Lau To: , David Miller CC: , Subject: Re: [PATCH net] l2tp: add sk_reuseport checks to l2tp_validate_socket Message-ID: <20200707183128.owsu62mnxp3k6lae@kafai-mbp> References: <20200706121259.GA20199@katalix.com> <20200706.124536.774178117550894539.davem@davemloft.net> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200706.124536.774178117550894539.davem@davemloft.net> User-Agent: NeoMutt/20180716 X-ClientProxiedBy: BY5PR04CA0021.namprd04.prod.outlook.com (2603:10b6:a03:1d0::31) To BY5PR15MB3571.namprd15.prod.outlook.com (2603:10b6:a03:1f6::32) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from kafai-mbp (2620:10d:c090:400::5:6c3d) by BY5PR04CA0021.namprd04.prod.outlook.com (2603:10b6:a03:1d0::31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3153.23 via Frontend Transport; Tue, 7 Jul 2020 18:31:29 +0000 X-Originating-IP: [2620:10d:c090:400::5:6c3d] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: fc832ad3-e2da-4205-7be7-08d822a3f743 X-MS-TrafficTypeDiagnostic: BYAPR15MB2824: X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-Forefront-PRVS: 0457F11EAF X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: YIoFSu2wFMRokrfO881BzwrGBTV4POZDQKPtCJTKdH2C2wVRGiDfptg0IW3q0oZAsXdZQWmls8kFZcd/oaeX0gPIJjGH++6nmRVZ/h6OAHW5KPtEIWBzFoIbrvgpHTFOT3/e7UNsEx6ZlyR35TMSZ8g/s0CTcQT1WAiXfkhQW4QZc8sWD8WDjT6nYL8PTkrFnTPRttqkTNhmWFeo4rntWekFbBUvEg1t3IW+IYShRAK/W/AQDaqoCrd+D9QVINutXIAROpHdEWnWgFMa18jzItN0c64Z2bHHD7gy3hzG9KivFbQXrnXYJrjdtNyxJwo2XvAMK16KXymoL9XcGaXWrg== X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY5PR15MB3571.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(136003)(366004)(376002)(39850400004)(396003)(346002)(6496006)(8936002)(86362001)(66946007)(33716001)(66476007)(66556008)(478600001)(55016002)(316002)(9686003)(1076003)(8676002)(4326008)(52116002)(16526019)(186003)(5660300002)(2906002)(6916009);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: fc832ad3-e2da-4205-7be7-08d822a3f743 X-MS-Exchange-CrossTenant-AuthSource: BY5PR15MB3571.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2020 18:31:29.8212 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 9hN4B+bXlHyJ8IDib5V6X7wdPcPgyaAn7ORHgJCi4Fv2K8iL/4hPa+MPE3sVXTVW X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2824 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-07-07_10:2020-07-07,2020-07-07 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 clxscore=1011 cotscore=-2147483648 mlxscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 impostorscore=0 spamscore=0 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2007070123 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jul 06, 2020 at 12:45:36PM -0700, David Miller wrote: > From: James Chapman > Date: Mon, 6 Jul 2020 13:12:59 +0100 > > > The crash occurs in the socket destroy path. bpf_sk_reuseport_detach > > assumes ownership of sk_user_data if sk_reuseport is set and writes a > > NULL pointer to the memory pointed to by > > sk_user_data. bpf_sk_reuseport_detach is called via > > udp_lib_unhash. l2tp does its socket cleanup through sk_destruct, > > which fetches private data through sk_user_data. The BUG_ON fires > > because this data has been corrupted. > > The ownership of sk_user_data has to be handled more cleanly. > > BPF really has no business taking over this as it is for the protocols > to use and what L2TP is doing is quite natural and normal. Exactly > what sk_user_data was designed to be used for. > > I'm not applying this, please take this up with the BPF folks. They > need to store their metadata elsewhere. Thanks for the report. The sk_user_data is used when a sk is added to the bpf's reuseport_sockarray. Before it can be added, the bpf side does check if the sk_user_data has already been used or not. It is the similar check like other usages on sk_user_data. The missing part is the reuseport_detach_sock() should check if a sk is currently in a reuseport_sockarray before calling bpf_sk_reuseport_detach(). It can be solved by remembering if a sk is added to the reuseport_sockarray. I will work on a fix by doing this.