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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0381CC77B7A for ; Wed, 17 May 2023 15:09:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9E39B900009; Wed, 17 May 2023 11:09:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9940A900003; Wed, 17 May 2023 11:09:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 88308900009; Wed, 17 May 2023 11:09:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 793FF900003 for ; Wed, 17 May 2023 11:09:16 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 4BDAAC0602 for ; Wed, 17 May 2023 15:09:16 +0000 (UTC) X-FDA: 80800080312.15.423473D Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf25.hostedemail.com (Postfix) with ESMTP id 4A281A0103 for ; Wed, 17 May 2023 15:07:11 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=XQbBabmZ; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684336033; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KcF1hvR5skYdKWqthLfWJRyn1Uj5JCRRCjlPP/5Hh8I=; b=Q77zhErDoZbmEYQEQ0Xr7fpqyOjMk/tXP4HOc8pDOfGh15L/SuydQNYs5d+eovPxyVZee4 MSyXDKXdKpcpUoUNmKFlGky1ebBzEsuj+f7782MfGLyMLzNcZzwWh7k5EbmF1i6jV6shqG PgLhyP0mxqUjkXUYCikx5yPAzJ4SKz4= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=XQbBabmZ; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684336033; a=rsa-sha256; cv=none; b=C6655r21F104+PagqB9LghYTnQH8wsGFRxGQ6fdE13S9NDod5J1+8eKplRV3QaFnjVia0c wwKWN7DRmx0+H+x2AjQxJOt5shuFd+rcgzwU1g8Lrz81c2aHbuIz/HhvslpEENU56QjW/Q wyjwFr7c8zQ5L84GLGqYNtTWhFjGlb0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1684336032; x=1715872032; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=m3M2b/UpB2Fp67mqL0iGGBx6gX63ZHkbp9fZFhoFbDc=; b=XQbBabmZapH/0Oy+JOxan9jdc8sAAUKcXCTxua+stXK40EVmlhVir/rB u3TIr69SsTJ5mUp27VvjEBmM6w/ULs7imD6EHOVUQrH1HfQYSetN92gXy 614hnYXoYrfXhJJmuA6hAZ4RgsfN+YYylG8an01CVHnCPH1NASTp8Wt5c Vv8zTy4WT4R9QkzKml/l6TE2YNQ396RhlKjJnphamBSOZ8PbdqJLrnnyW 4vkOtvHUknCqiUCkWUW51vGHojyfq9kT6S6SZ/r/At8tA+7HhE5QuOJXY yjmtaBjaHAb+tGN9FvJJKgaPYZT2HVE2hrmp/8RuMmfR3jZPAJrU4xOGf Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10713"; a="354083131" X-IronPort-AV: E=Sophos;i="5.99,282,1677571200"; d="scan'208";a="354083131" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 May 2023 08:07:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10713"; a="652277994" X-IronPort-AV: E=Sophos;i="5.99,282,1677571200"; d="scan'208";a="652277994" Received: from cbrown-mobl1.amr.corp.intel.com (HELO [10.212.129.207]) ([10.212.129.207]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 May 2023 08:07:07 -0700 Message-ID: Date: Wed, 17 May 2023 08:07:07 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1 Content-Language: en-US To: =?UTF-8?Q?Stephen_R=c3=b6ttger?= Cc: jeffxu@chromium.org, luto@kernel.org, jorgelo@chromium.org, keescook@chromium.org, groeck@chromium.org, jannh@google.com, akpm@linux-foundation.org, jeffxu@google.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org References: <20230515130553.2311248-1-jeffxu@chromium.org> <2bcffc9f-9244-0362-2da9-ece230055320@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: naw768k3uawa3coz7dbzpngw66e48wgw X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4A281A0103 X-Rspam-User: X-HE-Tag: 1684336031-356376 X-HE-Meta: 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 2nthxtH8 WoA0BdnHdfM/fafYgOe4dbK8dxcTt/4adgU2aIhbedZsYOLA5i3aNbaioSWmi18KZfxqqgbPTf7k1tq/WmseP5304g0Ow9DRKTNg/xEE3ynvJXNdZuat2Yqohe5f7HYUPsc0i1r0BP9wwAG07un3OWzV3JDh0DRj4UvmTolcJ9fjqpgM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 5/17/23 03:51, Stephen Röttger wrote: > On Wed, May 17, 2023 at 12:41 AM Dave Hansen wrote: >> Can't run arbitrary instructions, but can make (pretty) arbitrary syscalls? > > The threat model is that the attacker has arbitrary read/write, while other > threads run in parallel. So whenever a regular thread performs a syscall and > takes a syscall argument from memory, we assume that argument can be attacker > controlled. > Unfortunately, the line is a bit blurry which syscalls / syscall arguments we > need to assume to be attacker controlled. Ahh, OK. So, it's not that the *attacker* can make arbitrary syscalls. It's that the attacker might leverage its arbitrary write to trick a victim thread into turning what would otherwise be a good syscall into a bad one with attacker-controlled content. I guess that makes the readv/writev-style of things a bad idea in this environment. >>> Sigreturn is a separate problem that we hope to solve by adding pkey >>> support to sigaltstack >> >> What kind of support were you planning to add? > > We’d like to allow registering pkey-tagged memory as a sigaltstack. This would > allow the signal handler to run isolated from other threads. Right now, the > main reason this doesn’t work is that the kernel would need to change the pkru > state before storing the register state on the stack. > >> I was thinking that an attacker with arbitrary write access would wait >> until PKRU was on the userspace stack and *JUST* before the kernel >> sigreturn code restores it to write a malicious value. It could >> presumably do this with some asynchronous mechanism so that even if >> there was only one attacker thread, it could change its own value. > > I’m not sure I follow the details, can you give an example of an asynchronous > mechanism to do this? E.g. would this be the kernel writing to the memory in a > syscall for example? I was thinking of all of the IORING_OP_*'s that can write to memory or aio(7).