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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1505EC433E0 for ; Thu, 21 May 2020 10:46:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4559207FB for ; Thu, 21 May 2020 10:46:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728981AbgEUKqj convert rfc822-to-8bit (ORCPT ); Thu, 21 May 2020 06:46:39 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:60281 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728902AbgEUKqi (ORCPT ); Thu, 21 May 2020 06:46:38 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-221-qFd0NAKZNGeARFK-F-oKaQ-1; Thu, 21 May 2020 11:46:34 +0100 X-MC-Unique: qFd0NAKZNGeARFK-F-oKaQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Thu, 21 May 2020 11:46:33 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Thu, 21 May 2020 11:46:33 +0100 From: David Laight To: 'Christoph Hellwig' CC: "David S. Miller" , Jakub Kicinski , Eric Dumazet , Alexey Kuznetsov , Hideaki YOSHIFUJI , Vlad Yasevich , Neil Horman , "Marcelo Ricardo Leitner" , Jon Maloy , Ying Xue , "drbd-dev@lists.linbit.com" , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "target-devel@vger.kernel.org" , "linux-afs@lists.infradead.org" , "linux-cifs@vger.kernel.org" , "cluster-devel@redhat.com" , "ocfs2-devel@oss.oracle.com" , "netdev@vger.kernel.org" , "linux-sctp@vger.kernel.org" , "ceph-devel@vger.kernel.org" , "rds-devel@oss.oracle.com" , "linux-nfs@vger.kernel.org" Subject: RE: remove kernel_setsockopt and kernel_getsockopt v2 Thread-Topic: remove kernel_setsockopt and kernel_getsockopt v2 Thread-Index: AQHWL0EWFDRlmpM/90uRt9jvD36P/KiyKtMAgAAFoACAACnvQA== Date: Thu, 21 May 2020 10:46:33 +0000 Message-ID: References: <20200520195509.2215098-1-hch@lst.de> <138a17dfff244c089b95f129e4ea2f66@AcuMS.aculab.com> <20200521091150.GA8401@lst.de> In-Reply-To: <20200521091150.GA8401@lst.de> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: 'Christoph Hellwig' > Sent: 21 May 2020 10:12 ... > > I worried about whether getsockopt() should read the entire > > user buffer first. SCTP needs the some of it often (including a > > sockaddr_storage in one case), TCP needs it once. > > However the cost of reading a few words is small, and a big > > buffer probably needs setting to avoid leaking kernel > > memory if the structure has holes or fields that don't get set. > > Reading from userspace solves both issues. > > As mention in the thread on the last series: That was my first idea, but > we have way to many sockopts, especially in obscure protocols that just > hard code the size. The chance of breaking userspace in a way that can't > be fixed without going back to passing user pointers to get/setsockopt > is way to high to commit to such a change unfortunately. Right the syscall stubs probably can't do it. But the per-protocol ones can for the main protocols. I posted a patch for SCTP yesterday that removes 800 lines of source and 8k of object code. Even that needs a horrid bodge for one request where the length returned has to be less than the data copied! David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)