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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 E9056ECE587 for ; Tue, 1 Oct 2019 16:02:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1D7C21872 for ; Tue, 1 Oct 2019 16:02:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732908AbfJAQCF (ORCPT ); Tue, 1 Oct 2019 12:02:05 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:43234 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728249AbfJAQCE (ORCPT ); Tue, 1 Oct 2019 12:02:04 -0400 Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1iFKaw-0000Ns-A7; Tue, 01 Oct 2019 16:01:46 +0000 Date: Tue, 1 Oct 2019 18:01:45 +0200 From: Christian Brauner To: Aleksa Sarai , Kees Cook Cc: Ingo Molnar , Peter Zijlstra , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Rasmus Villemoes , Al Viro , Linus Torvalds , libc-alpha@sourceware.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 0/4] lib: introduce copy_struct_from_user() helper Message-ID: <20191001160144.z4y7gz4yla76apq4@wittgenstein> References: <20191001011055.19283-1-cyphar@cyphar.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20191001011055.19283-1-cyphar@cyphar.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 01, 2019 at 11:10:51AM +1000, Aleksa Sarai wrote: > Patch changelog: > v4: > * __always_inline copy_struct_from_user(). [Kees Cook] > * Rework test_user_copy.ko changes. [Kees Cook] > v3: > > v2: > v1: > > This series was split off from the openat2(2) syscall discussion[1]. > However, the copy_struct_to_user() helper has been dropped, because > after some discussion it appears that there is no really obvious > semantics for how copy_struct_to_user() should work on mixed-vintages > (for instance, whether [2] is the correct semantics for all syscalls). > > A common pattern for syscall extensions is increasing the size of a > struct passed from userspace, such that the zero-value of the new fields > result in the old kernel behaviour (allowing for a mix of userspace and > kernel vintages to operate on one another in most cases). > > Previously there was no common lib/ function that implemented > the necessary extension-checking semantics (and different syscalls > implemented them slightly differently or incompletely[3]). This series > implements the helper and ports several syscalls to use it. > > Some in-kernel selftests are included in this patch. More complete > self-tests for copy_struct_from_user() are included in the openat2() > patchset. > > [1]: https://lore.kernel.org/lkml/20190904201933.10736-1-cyphar@cyphar.com/ > > [2]: commit 1251201c0d34 ("sched/core: Fix uclamp ABI bug, clean up and > robustify sched_read_attr() ABI logic and code") > > [3]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > always rejects differently-sized struct arguments. > > Aleksa Sarai (4): > lib: introduce copy_struct_from_user() helper > clone3: switch to copy_struct_from_user() > sched_setattr: switch to copy_struct_from_user() > perf_event_open: switch to copy_struct_from_user() > > include/linux/bitops.h | 7 ++ > include/linux/uaccess.h | 70 +++++++++++++++++++ > include/uapi/linux/sched.h | 2 + > kernel/events/core.c | 47 +++---------- > kernel/fork.c | 34 ++-------- > kernel/sched/core.c | 43 ++---------- > lib/strnlen_user.c | 8 +-- > lib/test_user_copy.c | 136 +++++++++++++++++++++++++++++++++++-- > lib/usercopy.c | 55 +++++++++++++++ > 9 files changed, 288 insertions(+), 114 deletions(-) I've picked this up now and it's sitting in https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=copy_struct_from_user It should show up in linux-next tomorrow. I will let this sit there for a few days but overall this seems good to have in rc2. If someone objects and prefers to take it through their tree I can drop it. Christian