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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 24683C3A5AC for ; Thu, 5 Sep 2019 11:10:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07EC422CF6 for ; Thu, 5 Sep 2019 11:10:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388236AbfIELJz (ORCPT ); Thu, 5 Sep 2019 07:09:55 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:59887 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732051AbfIELJy (ORCPT ); Thu, 5 Sep 2019 07:09:54 -0400 Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i5pdd-0000xz-G0; Thu, 05 Sep 2019 11:09:17 +0000 Date: Thu, 5 Sep 2019 13:09:15 +0200 From: Christian Brauner To: Aleksa Sarai Cc: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Rasmus Villemoes , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190904201933.10736-2-cyphar@cyphar.com> User-Agent: NeoMutt/20180716 Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > 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). This is done > in both directions -- hence two helpers -- though it's more common to > have to copy user space structs into kernel space. > > Previously there was no common lib/ function that implemented > the necessary extension-checking semantics (and different syscalls > implemented them slightly differently or incompletely[1]). A future > patch replaces all of the common uses of this pattern to use the new > copy_struct_{to,from}_user() helpers. > > [1]: 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. > > Suggested-by: Rasmus Villemoes > Signed-off-by: Aleksa Sarai I would probably split this out into a separate patchset. It can very well go in before openat2(). Thoughts? Christian