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=-3.8 required=3.0 tests=BAYES_00, 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 8053EC4346A for ; Sun, 20 Sep 2020 18:12:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52B8C21D7A for ; Sun, 20 Sep 2020 18:12:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbgITSMR (ORCPT ); Sun, 20 Sep 2020 14:12:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726305AbgITSMP (ORCPT ); Sun, 20 Sep 2020 14:12:15 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C43F1C061755; Sun, 20 Sep 2020 11:12:14 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kK3om-002bUn-Fx; Sun, 20 Sep 2020 18:12:08 +0000 Date: Sun, 20 Sep 2020 19:12:08 +0100 From: Al Viro To: Andy Lutomirski Cc: Christoph Hellwig , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , linux-arm-kernel , X86 ML , LKML , "open list:MIPS" , Parisc List , linuxppc-dev , linux-s390 , sparclinux , linux-block , Linux SCSI List , Linux FS Devel , linux-aio , io-uring@vger.kernel.org, linux-arch , Linux-MM , Network Development , keyrings@vger.kernel.org, LSM List Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-ID: <20200920181208.GO3421308@ZenIV.linux.org.uk> References: <20200919224122.GJ3421308@ZenIV.linux.org.uk> <36CF3DE7-7B4B-41FD-9818-FDF8A5B440FB@amacapital.net> <20200919232411.GK3421308@ZenIV.linux.org.uk> <20200920025745.GL3421308@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Sun, Sep 20, 2020 at 09:59:36AM -0700, Andy Lutomirski wrote: > As one example, look at __sys_setsockopt(). It's called for the > native and compat versions, and it contains an in_compat_syscall() > check. (This particularly check looks dubious to me, but that's > another story.) If this were to be done with equivalent semantics > without a separate COMPAT_DEFINE_SYSCALL and without > in_compat_syscall(), there would need to be some indication as to > whether this is compat or native setsockopt. There are other > setsockopt implementations in the net stack with more > legitimate-seeming uses of in_compat_syscall() that would need some > other mechanism if in_compat_syscall() were to go away. > > setsockopt is (I hope!) out of scope for io_uring, but the situation > isn't fundamentally different from read and write. Except that setsockopt() had that crap very widespread; for read() and write() those are very rare exceptions. Andy, please RTFS. Or dig through archives. The situation with setsockopt() is *NOT* a good thing - it's (probably) the least of the evils. The last thing we need is making that the norm.