From patchwork Mon Feb 8 14:55:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Kiss X-Patchwork-Id: 12075811 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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 BE5CAC433DB for ; Mon, 8 Feb 2021 14:57:15 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 5CE7D64E0B for ; Mon, 8 Feb 2021 14:57:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5CE7D64E0B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: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:List-Owner; bh=E/2+e8UfY8Mo1Fn5jLykIzibDWQpyfTL3Trg4q6r1F8=; b=iIPZUl/vebftwORipzqa48uhQ 6CiQza0pLiMRPaOM6sHD4DvWyWRGuMhhZJPO3Zy7oAD9/FaqTWAluu4/6y6+DC543gOe/+uojXznb qZFahtFwADbXymnIO+u+WadH0FFXwYmOBzwEoSeYC3qQhPB5piNHZwXqhf600WrK7s+pZINAz8NQo QKkuua2lIFTVO/nYzsudpMPEmjHY068h/xKy7xjaIEB87PyFvBsnpH5a9P1yPj6qoQ9DDdrHixlkt 9Ne2Pz7S5cTyOdC33WYV/YPAV+WlSKZ76+Wl961o8H+X/oT6RNSPE98uUKwRDA9+J42fH212zAnyB RuAi6VHYQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l97xW-00025P-5s; Mon, 08 Feb 2021 14:56:14 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l97xQ-00023b-1R for linux-arm-kernel@lists.infradead.org; Mon, 08 Feb 2021 14:56:09 +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 4EBADED1; Mon, 8 Feb 2021 06:56:02 -0800 (PST) Received: from e120529.arm.com (unknown [10.37.8.4]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1AB1A3F719; Mon, 8 Feb 2021 06:56:00 -0800 (PST) From: Daniel Kiss To: linux-arm-kernel@lists.infradead.org, will@kernel.org Subject: [PATCH v3 1/2] arm64: Add ARM64_PTR_AUTH_KERNEL config option Date: Mon, 8 Feb 2021 15:55:53 +0100 Message-Id: <20210208145554.2164638-2-daniel.kiss@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210208145554.2164638-1-daniel.kiss@arm.com> References: <20210208145554.2164638-1-daniel.kiss@arm.com> MIME-Version: 1.0 X-ARM-No-Footer: FoSSMail X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210208_095608_219877_0FA2F046 X-CRM114-Status: GOOD ( 22.64 ) 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: Catalin.Marinas@arm.com, pcc@google.com, Ard.Biesheuvel@arm.com, Daniel Kiss Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch add the ARM64_PTR_AUTH_KERNEL config and deals with the build aspect of it. Userspace support has no dependency on the toolchain therefore all toolchain checks and build flags are controlled the new config option. The default config behavior will not be changed. Signed-off-by: Daniel Kiss Acked-by: Will Deacon --- arch/arm64/Kconfig | 33 +++++++++++++++++++-------------- arch/arm64/Makefile | 2 +- arch/arm64/kernel/asm-offsets.c | 2 ++ drivers/misc/lkdtm/bugs.c | 6 +++--- 4 files changed, 25 insertions(+), 18 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f39568b28ec1..c1268cdd6964 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1474,12 +1474,6 @@ menu "ARMv8.3 architectural features" config ARM64_PTR_AUTH bool "Enable support for pointer authentication" default y - depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC - # Modern compilers insert a .note.gnu.property section note for PAC - # which is only understood by binutils starting with version 2.33.1. - depends on LD_IS_LLD || LD_VERSION >= 233010000 || (CC_IS_GCC && GCC_VERSION < 90100) - depends on !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE - depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS) help Pointer authentication (part of the ARMv8.3 Extensions) provides instructions for signing and authenticating pointers against secret @@ -1491,13 +1485,6 @@ config ARM64_PTR_AUTH for each process at exec() time, with these keys being context-switched along with the process. - If the compiler supports the -mbranch-protection or - -msign-return-address flag (e.g. GCC 7 or later), then this option - will also cause the kernel itself to be compiled with return address - protection. In this case, and if the target hardware is known to - support pointer authentication, then CONFIG_STACKPROTECTOR can be - disabled with minimal loss of protection. - The feature is detected at runtime. If the feature is not present in hardware it will not be advertised to userspace/KVM guest nor will it be enabled. @@ -1508,6 +1495,24 @@ config ARM64_PTR_AUTH but with the feature disabled. On such a system, this option should not be selected. +config ARM64_PTR_AUTH_KERNEL + bool "Use pointer authentication for kernel" + default y + depends on ARM64_PTR_AUTH + depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC + # Modern compilers insert a .note.gnu.property section note for PAC + # which is only understood by binutils starting with version 2.33.1. + depends on LD_IS_LLD || LD_VERSION >= 233010000 || (CC_IS_GCC && GCC_VERSION < 90100) + depends on !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE + depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS) + help + If the compiler supports the -mbranch-protection or + -msign-return-address flag (e.g. GCC 7 or later), then this option + will cause the kernel itself to be compiled with return address + protection. In this case, and if the target hardware is known to + support pointer authentication, then CONFIG_STACKPROTECTOR can be + disabled with minimal loss of protection. + This feature works with FUNCTION_GRAPH_TRACER option only if DYNAMIC_FTRACE_WITH_REGS is enabled. @@ -1599,7 +1604,7 @@ config ARM64_BTI_KERNEL bool "Use Branch Target Identification for kernel" default y depends on ARM64_BTI - depends on ARM64_PTR_AUTH + depends on ARM64_PTR_AUTH_KERNEL depends on CC_HAS_BRANCH_PROT_PAC_RET_BTI # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697 depends on !CC_IS_GCC || GCC_VERSION >= 100100 diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 90309208bb28..a50b5e8231a7 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -70,7 +70,7 @@ endif # off, this will be overridden if we are using branch protection. branch-prot-flags-y += $(call cc-option,-mbranch-protection=none) -ifeq ($(CONFIG_ARM64_PTR_AUTH),y) +ifeq ($(CONFIG_ARM64_PTR_AUTH_KERNEL),y) branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all # We enable additional protection for leaf functions as there is some # narrow potential for ROP protection benefits and no substantial diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 301784463587..21c9f98f868d 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -45,6 +45,8 @@ int main(void) DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context)); #ifdef CONFIG_ARM64_PTR_AUTH DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user)); +#endif +#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL DEFINE(THREAD_KEYS_KERNEL, offsetof(struct task_struct, thread.keys_kernel)); #endif #ifdef CONFIG_ARM64_MTE diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index 110f5a8538e9..b5b809b3e1ef 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -446,7 +446,7 @@ void lkdtm_DOUBLE_FAULT(void) #ifdef CONFIG_ARM64 static noinline void change_pac_parameters(void) { - if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH)) { + if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) { /* Reset the keys of current task */ ptrauth_thread_init_kernel(current); ptrauth_thread_switch_kernel(current); @@ -460,8 +460,8 @@ noinline void lkdtm_CORRUPT_PAC(void) #define CORRUPT_PAC_ITERATE 10 int i; - if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH)) - pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH\n"); + if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) + pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n"); if (!system_supports_address_auth()) { pr_err("FAIL: CPU lacks pointer authentication feature\n");