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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7F587C433E6 for ; Sun, 7 Feb 2021 08:31:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B02F64E30 for ; Sun, 7 Feb 2021 08:31:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229522AbhBGIau (ORCPT ); Sun, 7 Feb 2021 03:30:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:58410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230174AbhBGI1j (ORCPT ); Sun, 7 Feb 2021 03:27:39 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 60C4564E30; Sun, 7 Feb 2021 08:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612686418; bh=iZLaC3K6FGWfQE8Z7GFLrLVt5OWKG6Rvey5Ve5cjNH8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Zs2NrYB/TuowYUapVOvW+Wf1wcukDT1WFaKInV+BguiJO3b1pATom0R+idEd9IR+n H1Z03Y/Cqn5muO4+SCYOnDMkHtUMXI1xnNxcaKnwaUeAWMnbOVcuXKZZ+eX/xWXdto ZzqC+DX6WKFny/t58M1kPHPC4O+t+bKyTYuXne6D1ohjqPVE16pAdIJ5Wh2f1jwob2 WH8CQPJ3hrxWwJtwmSkOO5dJkh/srg50le7DNO3Q2luOyQZp2Ro2mifGbzFRgfNbKP so9nglPQLIkCxxBXf2/Nwu5jvtDMySGfdEGXE+/EwwFjvc6yvm1xfRH37HKIpMNnLE LrxzYaA/11XxQ== Date: Sun, 7 Feb 2021 10:26:54 +0200 From: Leon Romanovsky To: Jakub Kicinski Cc: Arjun Roy , davem@davemloft.net, netdev@vger.kernel.org, arjunroy@google.com, edumazet@google.com, soheil@google.com, David Ahern Subject: Re: [net-next v2] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args. Message-ID: <20210207082654.GC4656@unreal> References: <20210206203648.609650-1-arjunroy.kdev@gmail.com> <20210206152828.6610da2b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210206152828.6610da2b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Feb 06, 2021 at 03:28:28PM -0800, Jakub Kicinski wrote: > On Sat, 6 Feb 2021 12:36:48 -0800 Arjun Roy wrote: > > From: Arjun Roy > > > > Explicitly define reserved field and require it to be 0-valued. > > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > > index e1a17c6b473c..c8469c579ed8 100644 > > --- a/net/ipv4/tcp.c > > +++ b/net/ipv4/tcp.c > > @@ -4159,6 +4159,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level, > > } > > if (copy_from_user(&zc, optval, len)) > > return -EFAULT; > > + if (zc.reserved) > > + return -EINVAL; > > lock_sock(sk); > > err = tcp_zerocopy_receive(sk, &zc, &tss); > > release_sock(sk); > > I was expecting we'd also throw in a check_zeroed_user(). > Either we can check if the buffer is zeroed all the way, > or we can't and we shouldn't validate reserved either > > check_zeroed_user(optval + offsetof(reserved), > len - offsetof(reserved)) > ? There is a check that len is not larger than zs and users can't give large buffer. I would say that is pretty safe to write "if (zc.reserved)". Thanks