From patchwork Fri Jun 4 10:04:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Kiss X-Patchwork-Id: 12299391 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=-17.1 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 0145CC07E94 for ; Fri, 4 Jun 2021 10:26:57 +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 C34B761009 for ; Fri, 4 Jun 2021 10:26:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C34B761009 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=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SA5+zbj/3dht27AUnWRUtN4RpwiLX2PWBBL8Ihb2KEU=; b=EpQ0EBfT94HqfO mmZN5rDQltwz+YoNsXRy/yZX8yZK0KlOplQKrLGWftkWfvCVtDEZ77BbsPDg2AiOk6BkADeP2W2wk tcfL4BS5gJv67nPojTsCliHHBViJ1OXnQhZrTPklsIc7PYe5MQM8uBCLMdh+oHzwoc7YahajWgSsI VUoyrihzIpn8Yl7zarDzpKBj+m30wOMPTDSzPmXr4hi1DZrDUI1Bu+I+MYODS+y+VHFyHmv2cI9Dm Ip3QiVSLljQAfihYhE/tHEV12qlZrq3RLn4y/lI2VnJlFlSxhtQ7ccD538msfXoLlCI+3Bb859Hyq G5nUMc/Gu9Vhs7L8o9uQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lp70k-00CwT6-08; Fri, 04 Jun 2021 10:25:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lp6hL-00Cnsp-Ce for linux-arm-kernel@lists.infradead.org; Fri, 04 Jun 2021 10:05:11 +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 AD99A1396; Fri, 4 Jun 2021 03:04:58 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 865A43F73D; Fri, 4 Jun 2021 03:04:57 -0700 (PDT) From: Daniel Kiss To: will@kernel.org Cc: Ard.Biesheuvel@arm.com, Catalin.Marinas@arm.com, linux-arm-kernel@lists.infradead.org, pcc@google.com, Daniel Kiss Subject: [PATCH v5 1/2] arm64: Add ARM64_PTR_AUTH_KERNEL config option Date: Fri, 4 Jun 2021 12:04:36 +0200 Message-Id: <20210604100437.1658599-2-daniel.kiss@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210604100437.1658599-1-daniel.kiss@arm.com> References: <20210604100437.1658599-1-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-20210604_030503_520873_A3441DF1 X-CRM114-Status: GOOD ( 21.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Reviewed-by: Catalin Marinas --- 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 9f1d8566bbf9..c0c0073a70c3 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1481,12 +1481,6 @@ 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 >= 23301 || (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 @@ -1498,13 +1492,6 @@ 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. @@ -1515,6 +1502,24 @@ 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. @@ -1606,7 +1611,7 @@ 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 b52481f0605d..3b5b1c480449 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 0cb34ccb6e73..03420b89c602 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -46,6 +46,8 @@ int main(void) DEFINE(THREAD_SCTLR_USER, offsetof(struct task_struct, thread.sctlr_user)); #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 0e8254d0cf0b..a164896dc6d4 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -463,7 +463,7 @@ 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); @@ -477,8 +477,8 @@ 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");