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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,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 7F453C433DB for ; Fri, 29 Jan 2021 20:53:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 42C8E64DE3 for ; Fri, 29 Jan 2021 20:53:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233301AbhA2Uwr (ORCPT ); Fri, 29 Jan 2021 15:52:47 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:43902 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233287AbhA2Uuv (ORCPT ); Fri, 29 Jan 2021 15:50:51 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 10TKnJVQ164431; Fri, 29 Jan 2021 20:49:51 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : references : message-id : date : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2020-01-29; bh=EFzN5/FMbOknUk3enKFydmPcydIk5NkKHtLJtLOhRss=; b=kY0p2Q5I7IwhIVj3BL6ufsCdCeDqJMxFlj7dzEO8OZ0mFHU5NHlvDTBcEll4Sj7Qu+/6 nF/94/HrLFd5TaBn2fwTA31Gdn8p5jSrz1rC3E1wV7T8DyRcly7ZJPoZUckoz/Yprcau ClEkmdYSbbcd9ZJq8RAEiJc33QrjyEfv9R6ZaKoe+IsXGpsbQfoFHxYHJBXKn57eEVQR SGu0dUOemFTuoweQDvN8if6kGUd2XRFSLx9ntgNLilJYp3tWQ3MbYvT0F9/MJKfid9gM CiLJKQBNvX2xzlrzWcWZsGPLY+LBhgx9OW4Bnv9BqPmgWH1mirBNC8kvAPHID/eZGAp0 vw== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by aserp2130.oracle.com with ESMTP id 3689ab3c43-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Jan 2021 20:49:50 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 10TKeIUf147360; Fri, 29 Jan 2021 20:49:50 GMT Received: from nam10-bn7-obe.outbound.protection.outlook.com (mail-bn7nam10lp2107.outbound.protection.outlook.com [104.47.70.107]) by userp3030.oracle.com with ESMTP id 368wr2fjhr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Jan 2021 20:49:50 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=DH7aZDpSiuJBPLb1QBbRF1u7ClJt1aDH4H8s6VVjUHqoDojE1TWBSF6cYtsC0BU8OHDK4jiZ8oB0rXL7tpL6e4fvuaV9bSjZ8jj94bfjOBjyfqTIca7JiRl+z1JIC9qFmta+/49+e7BY2G2AVo8xm2g8ivwS+Sr2OcffneNyavJAoYNsUN1yfyN6eGTnfJGhK4+edhQSHfGnQpkmiNSrvlwpOY3DI1aKcVE9ji8Oany23+IeaDxbKhtlRJV2OnLJV4JsI7SbOKoPaaIOuOkfbfZC23/fo52XLm+Xh2C77FPmlpWUYQGNBH562THLJ+kEKZf0FJYzw/PTcrFypO+j7w== 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=EFzN5/FMbOknUk3enKFydmPcydIk5NkKHtLJtLOhRss=; b=Y7gzKKuLWmKcWcbsTSp0h8c9NuafkjHD4OykJGQGc1uRiF6SCtxLkYjDP4UaDGFCMfPqSFju2r5L2HU8gboJ3ldiBIlJJVxX9PO8dDSSnfNmQNlLhBDOVoL4fJ5/7Z/7KbAtjFD1etzZ5OFRRgqKsaKZxS8tFekmcornSuCST9STvCSSchG8nbYRhEGkfXHjKKymp49ePrmoEl8IuRtxK/jvwjDj1rowC5/er81O8B2BpEBE34J9MLy1yRssK6sqc2isyNGB8zrnU8aBSNx2iFyUBrAzdQDLGZyTmChIy3iX2YW8OTLcz6wFzqHyu2yLACDyEDMyqdMVN3d3gnMw8A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=EFzN5/FMbOknUk3enKFydmPcydIk5NkKHtLJtLOhRss=; b=S5oSqPJX8aFS0FlPfJI3xNOkqBR8GKsihS93PYXHclTUIkgjaSc1+I0/X+7TmY6ZnV3g/ridBDZhcWEF0lvpUXGtnrrf12k9b9Fc6x6tjo2U6K7/vpf45GfmU/FGbCapWAMJQmQavqouAoKbRx5eEI+9kBAf0EjHk+5X1M/Hf4w= Authentication-Results: intel.com; dkim=none (message not signed) header.d=none;intel.com; dmarc=none action=none header.from=oracle.com; Received: from SJ0PR10MB4494.namprd10.prod.outlook.com (2603:10b6:a03:2d4::12) by BY5PR10MB4275.namprd10.prod.outlook.com (2603:10b6:a03:210::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3805.19; Fri, 29 Jan 2021 20:49:47 +0000 Received: from SJ0PR10MB4494.namprd10.prod.outlook.com ([fe80::7445:f44:72aa:da07]) by SJ0PR10MB4494.namprd10.prod.outlook.com ([fe80::7445:f44:72aa:da07%4]) with mapi id 15.20.3805.017; Fri, 29 Jan 2021 20:49:47 +0000 Subject: Re: [PATCH] af_unix: Allow Unix sockets to raise SIGURG From: Shoaib Rao To: Jakub Kicinski Cc: "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" , andy.rudoff@intel.com References: <20210122150638.210444-1-willy@infradead.org> <20210125153650.18c84b1a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <23fc3de2-7541-04c9-a56f-4006a7dc773f@oracle.com> <20210129110605.54df8409@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20210129120250.269c366d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20210129121837.467280fb@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Message-ID: <8915ad19-4a22-9124-8f79-4f003a512bd5@oracle.com> Date: Fri, 29 Jan 2021 12:49:45 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [2606:b400:8301:1010::16aa] X-ClientProxiedBy: BYAPR11CA0056.namprd11.prod.outlook.com (2603:10b6:a03:80::33) To SJ0PR10MB4494.namprd10.prod.outlook.com (2603:10b6:a03:2d4::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2606:b400:400:7446:8000::12a8] (2606:b400:8301:1010::16aa) by BYAPR11CA0056.namprd11.prod.outlook.com (2603:10b6:a03:80::33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3805.16 via Frontend Transport; Fri, 29 Jan 2021 20:49:47 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 56380984-f57d-422e-cf46-08d8c4976a56 X-MS-TrafficTypeDiagnostic: BY5PR10MB4275: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SJ0PR10MB4494.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(366004)(346002)(376002)(396003)(136003)(39860400002)(6486002)(2616005)(54906003)(4326008)(316002)(186003)(16526019)(478600001)(83380400001)(53546011)(31686004)(8936002)(6916009)(8676002)(31696002)(86362001)(2906002)(36756003)(5660300002)(66556008)(66946007)(66476007)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?eW5zQ2Q0Rm5paFUyNmtPTFI1KzFoZ2x3QVg4b1MyVDV1MGRZL2J5alYva2Y2?= =?utf-8?B?bWU1eDI0WDZBMFZBa1JQMVZ2eHFESm5mUE4xV2pKSEY4UlVLUDN1V2JYMWh0?= =?utf-8?B?V05zbVhLTzBSOWFGaG1QU0MrTVAwSW53YkplREdjR0lRZDd6cVNFQ2UyRDNv?= =?utf-8?B?WEYrdzczWFBCQ2JrZ0lNSk9UL0t0eHlMd0p3cW5ncml5c00wQXhhNGgvejlR?= =?utf-8?B?anR6dnlTYVR2YkUwcGN1UUMxa1NXTk1RRnJMd0lQSDE0S3IyTGF2NnRMYjJN?= =?utf-8?B?a2IwZjN3NnRxYmZhMEUvaTNJSmNHT1hoTHNkTW9CN3dCcmZFLzdhUVVGdHU1?= =?utf-8?B?R3oxOGlaSGtyNlR1ZU0yYkZZMUFEUFpCQTJqc2JrK1lqWjFEUXRYYUZFaUlC?= =?utf-8?B?UklILzJpZ1B2OExSbkhWTTJUemlRVC9tRk91dXFuVUowYm9XNTNIMk1jM1Mx?= =?utf-8?B?NGdsTDcwaFRTNHNjbjBVR1U4U1g1RXh6dXBqcUtlRThNNlZRN0p6STRWMXBx?= =?utf-8?B?L0hXYzdxYzljQ2JoOW8xc3JHT2xteW5EdGVFZDMwaWtFdlllSCs4Y2NZR3dH?= =?utf-8?B?OGZFQnhJQkZsS2VZQTVhMWQ2U0FTZnJnVE1qWmpBK2MyQjF0bjNncklMVXdp?= =?utf-8?B?dVQvcGNYRXlWckRFUFlkQmExcHBZZnpTaVZlWURqS2Z1NDRTMHdWYnhPVFEv?= =?utf-8?B?QWhITzFZNnZNdWdObVY5UHh2bk9kZFJjdFRUbDRIRVNZbXBtSUErckVZV3lL?= =?utf-8?B?YUFSc2x2d3hDZWwxaENFazJ5bWhzb0VjQWdxd3JFVURaUTlMclpoYjdwNTBy?= =?utf-8?B?WXR1RFJoSmZlOCs3SWNVTmg5U3VKY3k2eUlpenBPV1ZWa3lESHhualZ6STRq?= =?utf-8?B?WXV4SmZrc3F6em5oK1F6MkhMRTdLVVQwZXowRm5CSUJlWE5vclNibk9xNCs2?= =?utf-8?B?aGNYcXJjc3c3ZldHbjUzM1ZIQ1ROYkRBaHhKZHE5Um5HY1FkUDlrMnVEWXgz?= =?utf-8?B?bWJYamFZeHJrNVJvM1plbmRweXI0eWF0S1NGQ0Qza3pCZkkweGdSQklQY2Yx?= =?utf-8?B?R1l0bzdTaFo2Y2I5WTk0c0hDUmlybGRoY2x4NnJDQ2x0ZFNTS1BZMm1kUy9F?= =?utf-8?B?citpTExmcllVNVVPTlhRVnJ2Z1FuT3VjcTVUZHdwd0hVRHlSb0FQM0M1YVZB?= =?utf-8?B?K2J1dE4rNlZhY3licmQ0aU80SCswbXU5cWY2UmVGNVdHVlVsSVFBbzBCcWhW?= =?utf-8?B?YVVvZ0dOR2kzdnoyQ0RUT1E1TXV3dUlvNFhvVEtLeVJIRi84Q2tkWnZHZGJM?= =?utf-8?B?OUpOcXVCcmZUc24rOFdDcGtia3NSS0J4QnZOUkpsbSswR08vckZ6TFRadzdG?= =?utf-8?B?MDlLbHpIRjYySUw1QWw3cFVjVklseTY1Tmp4Ym5FdElxV0o1cEI5RnJNVkFh?= =?utf-8?B?UmpMOGc3UlRSZWplQ1dkTFN4VUs1T0xsNy80R1VVc2RicEl3Ry9VcGNKczlx?= =?utf-8?Q?9wHcqw=3D?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 56380984-f57d-422e-cf46-08d8c4976a56 X-MS-Exchange-CrossTenant-AuthSource: SJ0PR10MB4494.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jan 2021 20:49:47.7170 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: TwHROFyNf2LDLtqOTiso7DEkF6kHBy4+Ilk4QhHrHvFCLxkLF+r7XUHeN656SU+kAHT32z9D86SgF8hY9IDF/Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR10MB4275 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9879 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 phishscore=0 adultscore=0 mlxlogscore=924 malwarescore=0 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101290101 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9879 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 clxscore=1015 phishscore=0 bulkscore=0 spamscore=0 priorityscore=1501 mlxscore=0 suspectscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101290102 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 1/29/21 12:44 PM, Shoaib Rao wrote: > > On 1/29/21 12:18 PM, Jakub Kicinski wrote: >> On Fri, 29 Jan 2021 12:10:21 -0800 Shoaib Rao wrote: >>> On 1/29/21 12:02 PM, Jakub Kicinski wrote: >>>> On Fri, 29 Jan 2021 11:48:15 -0800 Shoaib Rao wrote: >>>>> Data was discarded because the flag was not supported, this patch >>>>> changes that but does not support any urgent data. >>>> When you say it does not support any urgent data do you mean the >>>> message len must be == 0 because something is checking it, or that >>>> the code does not support its handling? >>>> >>>> I'm perfectly fine with the former, just point me at the check, >>>> please. >>> The code does not care about the size of data -- All it does is that if >>> MSG_OOB is set it will deliver the signal to the peer process >>> irrespective of the length of the data (which can be zero length). >>> Let's >>> look at the code of unix_stream_sendmsg() It does the following >>> (sent is >>> initialized to zero) >> Okay. Let me try again. AFAICS your code makes it so that data sent >> with MSG_OOB is treated like any other data. It just sends a signal. > Correct. >> So you're hijacking the MSG_OOB to send a signal, because OOB also >> sends a signal. > Correct. >>   But there is nothing OOB about the data itself. > Correct. >>   So >> I'm asking you to make sure that there is no data in the message. > Yes I can do that. >> That way when someone wants _actual_ OOB data on UNIX sockets they >> can implement it without breaking backwards compatibility of the >> kernel uAPI. > > I see what you are trying to achieve. However it may not work. > > Let's assume that __actual__ OOB data has been implemented. An > application sends a zero length message with MSG_OOB, after that it > sends some data (not suppose to be OOB data). How is the receiver > going to differentiate if the data an OOB or not. > > We could use a different flag (MSG_SIGURG) or implement the _actual_ > OOB data semantics (If anyone is interested in it). MSG_SIGURG could > be a generic flag that just sends SIGURG irrespective of the length of > the data. > > Shoaib There is a relevant issue that I want to point out, Is it acceptable to send SIGURG without the receiver having any means to know what the urgent condition is? Shoaib > >> >>> while (sent < len) { >>>                   size = len - sent; >>> <..> >>> >>> } >>> >>>           if (msg->msg_flags & MSG_OOB) >>>                   sk_send_sigurg(other); >>> >>> Before the patch there was a check above the while loop that checked >>> the >>> flag and returned and error, that has been removed.