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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 2DDDDC3A5A5 for ; Thu, 5 Sep 2019 13:40:56 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9F7E12053B for ; Thu, 5 Sep 2019 13:40:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PTvR4twp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F7E12053B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=HQl96vk8bYu3ZjWCUfDLOtu2UlGQw8ixqRHttYx0dQA=; b=PTvR4twpDFAS8g5DGl7j9c//f mZgMfxQZeLTJk9fjwv9rXvLdMODTfUWi1r9f9v1W3EXiwkf7GZt122Fm5UQ7xcOj6wdlLNtEd42uA YV1DyqwrURiSS2uXN4lHs4ZXJGFdZEDdk2KzPMg3itoKNg8Rx69yjD8KxnaTzK4ADRObZhHCpDwkQ 2hdiJXWt6Xg2lLqfe8IRgYG9rAaY23CVqzl/VmOTFjdJIMHfB7SRrbr+sfeCjRM9GEq3caHcAD4k/ F8eTihiEt2HEIyzon3reyXv0sSIbNpSpdIawx8gjj6cNS6oVnM26jbC8J5P/whgbvhiSmE3YXsOet /SlZr/i9g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i5s0J-0006uu-Dw; Thu, 05 Sep 2019 13:40:51 +0000 Received: from mx2a.mailbox.org ([2001:67c:2050:104:0:2:25:2] helo=mx2.mailbox.org) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5s0F-0006uW-W4 for linux-arm-kernel@lists.infradead.org; Thu, 05 Sep 2019 13:40:49 +0000 Received: from smtp2.mailbox.org (smtp2.mailbox.org [80.241.60.241]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 641B2A2002; Thu, 5 Sep 2019 15:40:45 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id fp988BBgv0Z0; Thu, 5 Sep 2019 15:40:41 +0200 (CEST) Date: Thu, 5 Sep 2019 23:40:17 +1000 From: Aleksa Sarai To: Christian Brauner Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905134017.rstiqa6v6roslzlu@yavin.dot.cyphar.com> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> MIME-Version: 1.0 In-Reply-To: <20190905110544.d6c5t7rx25kvywmi@wittgenstein> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190905_064048_335726_9043C64B X-CRM114-Status: GOOD ( 21.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Rasmus Villemoes , Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , Jiri Olsa , Alexander Shishkin , Ingo Molnar , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, Al Viro , Andy Lutomirski , Shuah Khan , Namhyung Kim , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Content-Type: multipart/mixed; boundary="===============0802662071480975608==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0802662071480975608== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lfmn5rszd42a2efo" Content-Disposition: inline --lfmn5rszd42a2efo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > 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. > >=20 > > 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. > >=20 > > [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. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai [...] > > + if (unlikely(!access_ok(src, usize))) > > + return -EFAULT; > > + > > + /* Deal with trailing bytes. */ > > + if (usize < ksize) > > + memset(dst + size, 0, rest); [...] > That's a change in behavior for clone3() and sched at least, no? Unless > - which I guess you might have done - you have moved the "error out when > the struct is too small" part before the call to copy_struct_from_user() > for them. Yes, I've put the minimum size check to the callers in all of the cases (in the case of clone3() I've #define'd a CLONE_ARGS_SIZE_VER0 to match the others -- see patch 2 of the series). --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --lfmn5rszd42a2efo Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXEQPQAKCRCdlLljIbnQ EmI0AQDWLDq3CfEAPKhr2gyUgsbcgKNMnsXSA4qFj1Jjd61fzQEAqPhisgSoisGO mIYO56C9d94ktWhTGVP9Bs10TG3V/Ac= =1PLZ -----END PGP SIGNATURE----- --lfmn5rszd42a2efo-- --===============0802662071480975608== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============0802662071480975608==--