From patchwork Tue Apr 21 12:10:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 11501149 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CCE3281 for ; Tue, 21 Apr 2020 12:10:33 +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 A382E206A5 for ; Tue, 21 Apr 2020 12:10:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="huLkB+Q+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A382E206A5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=O0wFr3xPElp9clt/mN4ZZbi/BBZdFAY6Kaznr/C5dLY=; b=huL kB+Q+boyhU/zADafGiRDXaB3o3gxPRL6I4N5F2uYgE1bVk+o62/mSWkt9nmI1Pt+cyuTYmP7/b+VZ dqCGA5FS/3q19LRWpGktAufQIzy9bZo/qbed0Cs/QMWaziPY9Is6p4wnzCj2CCgsSkUNhCFXAnutj sDPE01M53Mv2G+Nie4HjnC4S8dk6FGXYjm8qhk9gvhAiqPWXTn/OpJMVfLwErKraDpZpmnWkW+yvc EL+zeYbSgCfxzvs2bgEfM9vb9IQwsjs8HnzvRxvdb48AyJtefuKcNeiT2TP25sxOh528MvdUJtYh+ ROa+1gtGN99238ioSX5uyem6l5seLaA==; 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 1jQrjR-0000oW-Rh; Tue, 21 Apr 2020 12:10:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jQrjO-0000nG-26 for linux-arm-kernel@lists.infradead.org; Tue, 21 Apr 2020 12:10:27 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6997B31B; Tue, 21 Apr 2020 05:10:22 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 769063F68F; Tue, 21 Apr 2020 05:10:21 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, will@kernel.org Subject: [PATCH] arm64: sync kernel APIAKey when installing Date: Tue, 21 Apr 2020 13:10:14 +0100 Message-Id: <20200421121014.53120-1-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200421_051026_145073_5F9A70F4 X-CRM114-Status: GOOD ( 12.43 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 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: Mark Rutland , Amit Daniel Kachhap , Marc Zyngier , Catalin Marinas MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org A direct write to a APxxKey_EL1 register requires a context synchronization event to ensure that indirect reads made by subsequent instructions (e.g. AUTIASP, PACIASP) observe the new value. When we initialize the boot task's APIAKey in boot_init_stack_canary() via ptrauth_keys_switch_kernel() we miss the necessary ISB, and so there is a window where instructions are not guaranteed to use the new APIAKey value. This has been observed to result in boot-time crashes where PACIASP and AUTIASP within a function used a mixture of the old and new key values. Fix this by having ptrauth_keys_switch_kernel() synchronize the new key value with an ISB. At the same time, __ptrauth_key_install() is renamed to __ptrauth_key_install_nosync() so that it is obvious that this performs no synchronization itself. Fixes: 28321582334c261c ("arm64: initialize ptrauth keys for kernel booting task") Signed-off-by: Mark Rutland Reported-by: Will Deacon Cc: Amit Daniel Kachhap Cc: Catalin Marinas Cc: Marc Zyngier Tested-by: Will Deacon --- arch/arm64/include/asm/pointer_auth.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h index 70c47156e54b..c6b4f0603024 100644 --- a/arch/arm64/include/asm/pointer_auth.h +++ b/arch/arm64/include/asm/pointer_auth.h @@ -47,7 +47,7 @@ static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys) get_random_bytes(&keys->apga, sizeof(keys->apga)); } -#define __ptrauth_key_install(k, v) \ +#define __ptrauth_key_install_nosync(k, v) \ do { \ struct ptrauth_key __pki_v = (v); \ write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \ @@ -62,8 +62,11 @@ static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys) { - if (system_supports_address_auth()) - __ptrauth_key_install(APIA, keys->apia); + if (!system_supports_address_auth()) + return; + + __ptrauth_key_install_nosync(APIA, keys->apia); + isb(); } extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);