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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 25014C47404 for ; Fri, 11 Oct 2019 15:25:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED79D206A1 for ; Fri, 11 Oct 2019 15:25:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="E0dKoxgv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727849AbfJKPZh (ORCPT ); Fri, 11 Oct 2019 11:25:37 -0400 Received: from mail-yb1-f194.google.com ([209.85.219.194]:41568 "EHLO mail-yb1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726707AbfJKPZh (ORCPT ); Fri, 11 Oct 2019 11:25:37 -0400 Received: by mail-yb1-f194.google.com with SMTP id 206so3221200ybc.8 for ; Fri, 11 Oct 2019 08:25:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:openpgp:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=hjVVG+LCl45Ap93nqrjHPaMZ4hTq+jdNOcLl2h2isR4=; b=E0dKoxgvUXWjFVVVks6GzW0TjExH0yK1lnbi91wV8UOgJXhezVXn6TKlZ8HQUqA4LB Ocx5BzIjuxG958WumzE9PHeFIKmdin8uJ80H+haes7A8Uss5tac+84Bu78gsZut6QXAH lAk8SDxXuvS8brS+1lB1ksHLQ4k/RGyUL6wLn/UpINn7yR8VT+jswqGAyCr8ZhDTczre 5iQpR0zvXXa+jUNmN6dDOszzNYTbsXpTuYHQnlbsTKD8jioNaXyu0auTjxbbs/cFails zGhGXYBrnMUWJ8wU2JABRejO0vxitMy0Ol37RK7oCzGgGTyKxkikYq8uCPF7weNSTt9/ JvtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=hjVVG+LCl45Ap93nqrjHPaMZ4hTq+jdNOcLl2h2isR4=; b=hn8IcF3+Quwc+xCkDl3RY+Ll/tVudtTl0HTR6PNX7MAVP/3Gy73zuTQQxR5poD7lCb YgEILmbDRQSz2V0f7HZT5hQCH5nPZtd0peoawIXBA/8yp648BSqLNQqd7gpRY0a5i9X8 JGnPtKmRLnL6E1kVQ2li4hT3blGU7WbmglT7heTBpi/xgE9kCFE8B0mFmr6ujV6v+HRD RXHlFb4/EmdsvsNNUusXJEfQiSGcSU04yej6OGC5BUAcKoCnOfZnd2LvAB6W6k8mhRWA 26CtyJ1sn5quX7lda+f4s7h+1/buDyTyOBGSNkCWCJX8NddFGC6Q0trmLd2nq1LQQYAr DTlQ== X-Gm-Message-State: APjAAAVBcCGWszmjZXJ2i1bChOmt7Ch1wwt7ejBYipoNR13wqmmALn+4 1O+pA1bqDyrWM5KlGM/sR61/eA== X-Google-Smtp-Source: APXvYqysY7dY5L83dfJIuaCR944gcYiW6Lfi2SqxpcDRGH/9Id6HpLLJrRLEW2oTFhfQatKUSjZZtg== X-Received: by 2002:a25:2d49:: with SMTP id s9mr9205759ybe.450.1570807536250; Fri, 11 Oct 2019 08:25:36 -0700 (PDT) Received: from [192.168.1.44] (67.216.151.25.pool.hargray.net. [67.216.151.25]) by smtp.gmail.com with ESMTPSA id t82sm2316781ywc.26.2019.10.11.08.25.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Oct 2019 08:25:35 -0700 (PDT) Subject: Re: [PATCH v2 05/12] arm64: Basic Branch Target Identification support To: Mark Rutland , Dave Martin Cc: linux-kernel@vger.kernel.org, Andrew Jones , Arnd Bergmann , Catalin Marinas , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Kees Cook , =?UTF-8?Q?Kristina_Mart=c5=a1enko?= , Mark Brown , Paul Elliott , Peter Zijlstra , Sudakshina Das , Szabolcs Nagy , Thomas Gleixner , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com> <1570733080-21015-6-git-send-email-Dave.Martin@arm.com> <20191011151028.GE33537@lakrids.cambridge.arm.com> From: Richard Henderson Openpgp: preference=signencrypt Message-ID: <4e09ca54-f353-9448-64ed-4ba1e38c6ebc@linaro.org> Date: Fri, 11 Oct 2019 11:25:33 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191011151028.GE33537@lakrids.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/11/19 11:10 AM, Mark Rutland wrote: > On Thu, Oct 10, 2019 at 07:44:33PM +0100, Dave Martin wrote: >> @@ -730,6 +730,11 @@ static void setup_return >> regs->regs[29] = (unsigned long)&user->next_frame->fp; >> regs->pc = (unsigned long)ka->sa.sa_handler; >> >> + if (system_supports_bti()) { >> + regs->pstate &= ~PSR_BTYPE_MASK; >> + regs->pstate |= PSR_BTYPE_CALL; >> + } >> + > > I think we might need a comment as to what we're trying to ensure here. > > I was under the (perhaps mistaken) impression that we'd generate a > pristine pstate for a signal handler, and it's not clear to me that we > must ensure the first instruction is a target instruction. I think it makes sense to treat entry into a signal handler as a call. Code that has been compiled for BTI, and whose page has been marked with PROT_BTI, will already have the pauth/bti markup at the beginning of the signal handler function; we might as well verify that. Otherwise sigaction becomes a hole by which an attacker can force execution to start at any arbitrary address. r~ From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Henderson Subject: Re: [PATCH v2 05/12] arm64: Basic Branch Target Identification support Date: Fri, 11 Oct 2019 11:25:33 -0400 Message-ID: <4e09ca54-f353-9448-64ed-4ba1e38c6ebc@linaro.org> References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com> <1570733080-21015-6-git-send-email-Dave.Martin@arm.com> <20191011151028.GE33537@lakrids.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20191011151028.GE33537@lakrids.cambridge.arm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Mark Rutland , Dave Martin Cc: linux-kernel@vger.kernel.org, Andrew Jones , Arnd Bergmann , Catalin Marinas , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Kees Cook , =?UTF-8?Q?Kristina_Mart=c5=a1enko?= , Mark Brown , Paul Elliott , Peter Zijlstra , Sudakshina Das , Szabolcs Nagy , Thomas Gleixner , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino List-Id: linux-arch.vger.kernel.org On 10/11/19 11:10 AM, Mark Rutland wrote: > On Thu, Oct 10, 2019 at 07:44:33PM +0100, Dave Martin wrote: >> @@ -730,6 +730,11 @@ static void setup_return >> regs->regs[29] = (unsigned long)&user->next_frame->fp; >> regs->pc = (unsigned long)ka->sa.sa_handler; >> >> + if (system_supports_bti()) { >> + regs->pstate &= ~PSR_BTYPE_MASK; >> + regs->pstate |= PSR_BTYPE_CALL; >> + } >> + > > I think we might need a comment as to what we're trying to ensure here. > > I was under the (perhaps mistaken) impression that we'd generate a > pristine pstate for a signal handler, and it's not clear to me that we > must ensure the first instruction is a target instruction. I think it makes sense to treat entry into a signal handler as a call. Code that has been compiled for BTI, and whose page has been marked with PROT_BTI, will already have the pauth/bti markup at the beginning of the signal handler function; we might as well verify that. Otherwise sigaction becomes a hole by which an attacker can force execution to start at any arbitrary address. r~ 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0A45FC47404 for ; Fri, 11 Oct 2019 15:25:49 +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 D1E50206A1 for ; Fri, 11 Oct 2019 15:25:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XRtw7Nsd"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="E0dKoxgv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1E50206A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=dG9q337jRLrGdo8E+urN4pEGnWvfCPQVaHYQ2oReVkI=; b=XRtw7Nsdk3ylgf KQholgNmOgvDvCMFtZP0q0Sr4vHLzF1hNtwb+As96BLNvrINwNPslUyZ3b4bDVg1pQ1y9N74GrwWa 37wD85KF20/9gJxKpJcOmYWmQq6+XFUYzhiFi4IgReGbqvWyE30CppA8ZW0ZcnbNIvRLGsh6OQqrK K1EkJthC8QlpGS+G1xzGQFSyjPx9AsmEgfhU3/8V7+/PUDY4cmFX+rdkyM1i1b64wBakhxguxXm06 ftsQD/LcFpxBQQArli/q/thKyU4IE9JtrHJDazmRYLh4YPcfmA9Rs5BOaPNq58QdBcIEDPrJCEfLE 1qUyjFjTRaC+ibUhb8+Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIwnV-000105-Bw; Fri, 11 Oct 2019 15:25:41 +0000 Received: from mail-yb1-xb43.google.com ([2607:f8b0:4864:20::b43]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIwnS-0000zH-Ka for linux-arm-kernel@lists.infradead.org; Fri, 11 Oct 2019 15:25:39 +0000 Received: by mail-yb1-xb43.google.com with SMTP id y204so3212743yby.10 for ; Fri, 11 Oct 2019 08:25:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:openpgp:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=hjVVG+LCl45Ap93nqrjHPaMZ4hTq+jdNOcLl2h2isR4=; b=E0dKoxgvUXWjFVVVks6GzW0TjExH0yK1lnbi91wV8UOgJXhezVXn6TKlZ8HQUqA4LB Ocx5BzIjuxG958WumzE9PHeFIKmdin8uJ80H+haes7A8Uss5tac+84Bu78gsZut6QXAH lAk8SDxXuvS8brS+1lB1ksHLQ4k/RGyUL6wLn/UpINn7yR8VT+jswqGAyCr8ZhDTczre 5iQpR0zvXXa+jUNmN6dDOszzNYTbsXpTuYHQnlbsTKD8jioNaXyu0auTjxbbs/cFails zGhGXYBrnMUWJ8wU2JABRejO0vxitMy0Ol37RK7oCzGgGTyKxkikYq8uCPF7weNSTt9/ JvtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=hjVVG+LCl45Ap93nqrjHPaMZ4hTq+jdNOcLl2h2isR4=; b=iPS/NppVWWNM0090HXzvvPbf4JzQB1sKMSDhJUjUoOcN2SWsW3hpRckqD3NZuWvIOl u4Ig9I9P7Kl32TwwPrh1eOGxpBlOexLnm6mRuNPyRrr7vnQ6IdGAJ+tWWwy2d4sBN6Se JN5TSyr3Te249jzPjD6kQs1vIHgF76EU5qevwS/RYuyCukPdR9Ni4WLVznz19kRh5TvQ g4qb0VMPrzo622GZxARx28g7f3nOz/d1x3578NDj3xJGy4UqmAvx5g+DjWQswsWB1Tu7 HnOFUFsCOg0bBQUUqRhtPcduXffJlQBkQI3n+l2M38pzNjrrBX0ZcER9kmvn+bwcNq5/ 9Jew== X-Gm-Message-State: APjAAAXGkP7hu6ApJrjgk1yDZH09ld93wzX5d+/rCs6WHbH6LOkmL0Ra DwwBhsf9WIWE5m1mcLHnGEsBMWavsMk= X-Google-Smtp-Source: APXvYqysY7dY5L83dfJIuaCR944gcYiW6Lfi2SqxpcDRGH/9Id6HpLLJrRLEW2oTFhfQatKUSjZZtg== X-Received: by 2002:a25:2d49:: with SMTP id s9mr9205759ybe.450.1570807536250; Fri, 11 Oct 2019 08:25:36 -0700 (PDT) Received: from [192.168.1.44] (67.216.151.25.pool.hargray.net. [67.216.151.25]) by smtp.gmail.com with ESMTPSA id t82sm2316781ywc.26.2019.10.11.08.25.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Oct 2019 08:25:35 -0700 (PDT) Subject: Re: [PATCH v2 05/12] arm64: Basic Branch Target Identification support To: Mark Rutland , Dave Martin References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com> <1570733080-21015-6-git-send-email-Dave.Martin@arm.com> <20191011151028.GE33537@lakrids.cambridge.arm.com> From: Richard Henderson Openpgp: preference=signencrypt Message-ID: <4e09ca54-f353-9448-64ed-4ba1e38c6ebc@linaro.org> Date: Fri, 11 Oct 2019 11:25:33 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191011151028.GE33537@lakrids.cambridge.arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191011_082538_679328_08616060 X-CRM114-Status: GOOD ( 16.01 ) 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: Paul Elliott , Peter Zijlstra , Catalin Marinas , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , linux-arch@vger.kernel.org, Eugene Syromiatnikov , Szabolcs Nagy , "H.J. Lu" , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , =?UTF-8?Q?Kristina_Mart=c5=a1enko?= , Mark Brown , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Florian Weimer , linux-kernel@vger.kernel.org, Sudakshina Das Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 10/11/19 11:10 AM, Mark Rutland wrote: > On Thu, Oct 10, 2019 at 07:44:33PM +0100, Dave Martin wrote: >> @@ -730,6 +730,11 @@ static void setup_return >> regs->regs[29] = (unsigned long)&user->next_frame->fp; >> regs->pc = (unsigned long)ka->sa.sa_handler; >> >> + if (system_supports_bti()) { >> + regs->pstate &= ~PSR_BTYPE_MASK; >> + regs->pstate |= PSR_BTYPE_CALL; >> + } >> + > > I think we might need a comment as to what we're trying to ensure here. > > I was under the (perhaps mistaken) impression that we'd generate a > pristine pstate for a signal handler, and it's not clear to me that we > must ensure the first instruction is a target instruction. I think it makes sense to treat entry into a signal handler as a call. Code that has been compiled for BTI, and whose page has been marked with PROT_BTI, will already have the pauth/bti markup at the beginning of the signal handler function; we might as well verify that. Otherwise sigaction becomes a hole by which an attacker can force execution to start at any arbitrary address. r~ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel