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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A605C4332F for ; Wed, 13 Dec 2023 19:48:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378712AbjLMTse (ORCPT ); Wed, 13 Dec 2023 14:48:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229811AbjLMTsd (ORCPT ); Wed, 13 Dec 2023 14:48:33 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2C039C for ; Wed, 13 Dec 2023 11:48:39 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7215AC433C7; Wed, 13 Dec 2023 19:48:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702496919; bh=MZtzdUx4eKT5heieT9T5VOR43tMJJzsqr7+1whfzXas=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=V7uGFuNHvpesCeFV2U++2OplcF8v4oBAlDcXfknxMkfBwIOdoPbiDOhepHt8u3hhn dJiojJM/VfCGpAMnMesfB4H5uCicK1y5jxuLv5FHILPBXat0VWi1iOAoOxU9gZgZUb l8M7QsbawfZos/ahINA3IdeLESlKIPE1+bhtG7e0PXeiC1L6nRYSvOEzGoUYGsfozI ekB6+Al5sf4osUXPOvKnkbVafY9lGZk41toCjgNPFfTlwkNnZHVtW7V8nOHGoDgxSp wCdSCFc4lrTp0SYb/2qv/dL0X/a4SRA2op13Gh+K9k9gMcYs8U87M2mqMuH+YfwILd GnU5OqCI0duSA== Date: Wed, 13 Dec 2023 19:48:28 +0000 From: Mark Brown To: Deepak Gupta Cc: Catalin Marinas , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Ard Biesheuvel , Szabolcs Nagy , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v7 02/39] prctl: arch-agnostic prctl for shadow stack Message-ID: References: <20231122-arm64-gcs-v7-0-201c483bd775@kernel.org> <20231122-arm64-gcs-v7-2-201c483bd775@kernel.org> <0d0d8802-09e3-4ea5-a0b4-b3a08c8a282e@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="PqL9xaSuINxjZ0qj" Content-Disposition: inline In-Reply-To: X-Cookie: One size fits all. Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --PqL9xaSuINxjZ0qj Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Dec 13, 2023 at 11:43:49AM -0800, Deepak Gupta wrote: > On Wed, Dec 13, 2023 at 5:37=E2=80=AFAM Mark Brown w= rote: > > On Tue, Dec 12, 2023 at 04:50:38PM -0800, Deepak Gupta wrote: > > > How will it do that (currently _ENABLE is married to _WRITE and _PUSH= ) ? > > That's feeling moderately firmly into "don't do that" territory to be > > honest, the problems of trying to modify the stack of another running > > thread while it's active just don't seem worth it - if you're > > coordinating enough to do the modifications it's probably possible to > > just ask the thread who's stack is being modified to do the modification > > itself and having an unprotected thread writing into shadow stack memory > > doesn't feel great. > Yeah no leanings on my side. Just wanted to articulate this scenario. > Since this is new ground, > we can define what's appropriate. Let's keep it this way where a > thread can write to shadow > stack mappings only when it itself has shadow stack enabled. Sounds good to me - it's much easier to relax permissions later than to tighten them up. --PqL9xaSuINxjZ0qj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmV6CosACgkQJNaLcl1U h9ALhgf/X0uXQk/jQmE5Jq0LTM5Dq11ls+1yrW1dnXA7KxS0COIsEEUbdISRGMla V+YwOPaYph3UvrmaWSwwvJoYLBnF5otV9j195V9CyQ0+ffNtfzadl8v/tCaf9Kj8 w3gJY/USQR8ILQtuKGWengTYUOgoygMfNi5bjUokSG8R06ZNY9d51H/aOjGUgnUQ 8EaJ6bxBsbsqd4FlcP8EcxYfwdpfhEf9EKrHF+ZIlHTZdP4abSGD5mb7B1w4Tqpj iVf/C2FzA5H8OSh7cMg/9WfDUCs74i+AUc2sIVVpFNYvfcxyCqQIfdwk5Okiyc8t LBjtoBgkATaNC4M22Ino8jfc5Dasew== =qiqv -----END PGP SIGNATURE----- --PqL9xaSuINxjZ0qj--