From patchwork Fri Sep 4 10:42:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Daniel Kachhap X-Patchwork-Id: 11756597 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 7ACD8618 for ; Fri, 4 Sep 2020 10:42:57 +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 523762087C for ; Fri, 4 Sep 2020 10:42:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Q2yMYRo9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 523762087C 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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id: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=ZDK8uBJDLaOc2HJnSSu+zyELwBLkgqBf1fr3ory3uhk=; b=Q2yMYRo9iNYQuN7FGSchLeQNCl A/B+Pm39s8hmyHbdLMiNg4GK79PR5lhoJBSkOZZz/R5cIE9fGNRUWbOfLA0rAJ450DCRS2bqCi5lI 4ZgmcDIpaat4KDR9hsm04He497A6lXWZxEDwWAXNBt4au1k7RFVjdkP+iLDLSmuI9dRIAR3iDt59y pryAC+jUkOT873TcKBRVsaXBC0rDYk7pIvFre2ooH99W/r2eDzSIoAO4jzehx3DnQbfIyCV2GIVif s2bRKiZDyNSCzEMh1QM4eXaNH/ug+QfkxY6aFvJOSKXh8vTcrZYYqlRtFRVxerD54i5n41W0+53GL MkQXFtuA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kE9B5-0002zH-8d; Fri, 04 Sep 2020 10:42:43 +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 1kE9Az-0002xD-FJ for linux-arm-kernel@lists.infradead.org; Fri, 04 Sep 2020 10:42:38 +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 795C9101E; Fri, 4 Sep 2020 03:42:33 -0700 (PDT) Received: from a077416.arm.com (unknown [10.57.5.177]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 522E43F66F; Fri, 4 Sep 2020 03:42:30 -0700 (PDT) From: Amit Daniel Kachhap To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v6 3/6] arm64: ptrauth: Introduce Armv8.3 pointer authentication enhancements Date: Fri, 4 Sep 2020 16:12:06 +0530 Message-Id: <20200904104209.32385-4-amit.kachhap@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200904104209.32385-1-amit.kachhap@arm.com> References: <20200904104209.32385-1-amit.kachhap@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200904_064237_636106_46C66227 X-CRM114-Status: GOOD ( 20.39 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.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 , Suzuki K Poulose , Catalin Marinas , Mark Brown , James Morse , Amit Daniel Kachhap , Vincenzo Frascino , Will Deacon , Dave Martin MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Some Armv8.3 Pointer Authentication enhancements have been introduced which are mandatory for Armv8.6 and optional for Armv8.3. These features are, * ARMv8.3-PAuth2 - An enhanced PAC generation logic is added which hardens finding the correct PAC value of the authenticated pointer. * ARMv8.3-FPAC - Fault is generated now when the ptrauth authentication instruction fails in authenticating the PAC present in the address. This is different from earlier case when such failures just adds an error code in the top byte and waits for subsequent load/store to abort. The ptrauth instructions which may cause this fault are autiasp, retaa etc. The above features are now represented by additional configurations for the Address Authentication cpufeature and a new ESR exception class. The userspace fault received in the kernel due to ARMv8.3-FPAC is treated as Illegal instruction and hence signal SIGILL is injected with ILL_ILLOPN as the signal code. Note that this is different from earlier ARMv8.3 ptrauth where signal SIGSEGV is issued due to Pointer authentication failures. The in-kernel PAC fault causes kernel to crash. Signed-off-by: Amit Daniel Kachhap Reviewed-by: Dave Martin --- Changes since v5: * Modified comment as suggested by Dave. * Added Reviewed-by. arch/arm64/include/asm/esr.h | 4 +++- arch/arm64/include/asm/exception.h | 1 + arch/arm64/include/asm/sysreg.h | 24 ++++++++++++++++-------- arch/arm64/kernel/entry-common.c | 21 +++++++++++++++++++++ arch/arm64/kernel/traps.c | 12 ++++++++++++ 5 files changed, 53 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index 035003acfa87..22c81f1edda2 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -35,7 +35,9 @@ #define ESR_ELx_EC_SYS64 (0x18) #define ESR_ELx_EC_SVE (0x19) #define ESR_ELx_EC_ERET (0x1a) /* EL2 only */ -/* Unallocated EC: 0x1b - 0x1E */ +/* Unallocated EC: 0x1B */ +#define ESR_ELx_EC_FPAC (0x1C) /* EL1 and above */ +/* Unallocated EC: 0x1D - 0x1E */ #define ESR_ELx_EC_IMP_DEF (0x1f) /* EL3 only */ #define ESR_ELx_EC_IABT_LOW (0x20) #define ESR_ELx_EC_IABT_CUR (0x21) diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h index 7577a754d443..99b9383cd036 100644 --- a/arch/arm64/include/asm/exception.h +++ b/arch/arm64/include/asm/exception.h @@ -47,4 +47,5 @@ void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr); void do_cp15instr(unsigned int esr, struct pt_regs *regs); void do_el0_svc(struct pt_regs *regs); void do_el0_svc_compat(struct pt_regs *regs); +void do_ptrauth_fault(struct pt_regs *regs, unsigned int esr); #endif /* __ASM_EXCEPTION_H */ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 554a7e8ecb07..b738bc793369 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -636,14 +636,22 @@ #define ID_AA64ISAR1_APA_SHIFT 4 #define ID_AA64ISAR1_DPB_SHIFT 0 -#define ID_AA64ISAR1_APA_NI 0x0 -#define ID_AA64ISAR1_APA_ARCHITECTED 0x1 -#define ID_AA64ISAR1_API_NI 0x0 -#define ID_AA64ISAR1_API_IMP_DEF 0x1 -#define ID_AA64ISAR1_GPA_NI 0x0 -#define ID_AA64ISAR1_GPA_ARCHITECTED 0x1 -#define ID_AA64ISAR1_GPI_NI 0x0 -#define ID_AA64ISAR1_GPI_IMP_DEF 0x1 +#define ID_AA64ISAR1_APA_NI 0x0 +#define ID_AA64ISAR1_APA_ARCHITECTED 0x1 +#define ID_AA64ISAR1_APA_ARCH_EPAC 0x2 +#define ID_AA64ISAR1_APA_ARCH_EPAC2 0x3 +#define ID_AA64ISAR1_APA_ARCH_EPAC2_FPAC 0x4 +#define ID_AA64ISAR1_APA_ARCH_EPAC2_FPAC_CMB 0x5 +#define ID_AA64ISAR1_API_NI 0x0 +#define ID_AA64ISAR1_API_IMP_DEF 0x1 +#define ID_AA64ISAR1_API_IMP_DEF_EPAC 0x2 +#define ID_AA64ISAR1_API_IMP_DEF_EPAC2 0x3 +#define ID_AA64ISAR1_API_IMP_DEF_EPAC2_FPAC 0x4 +#define ID_AA64ISAR1_API_IMP_DEF_EPAC2_FPAC_CMB 0x5 +#define ID_AA64ISAR1_GPA_NI 0x0 +#define ID_AA64ISAR1_GPA_ARCHITECTED 0x1 +#define ID_AA64ISAR1_GPI_NI 0x0 +#define ID_AA64ISAR1_GPI_IMP_DEF 0x1 /* id_aa64pfr0 */ #define ID_AA64PFR0_CSV3_SHIFT 60 diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index d3be9dbf5490..43d4c329775f 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -66,6 +66,13 @@ static void notrace el1_dbg(struct pt_regs *regs, unsigned long esr) } NOKPROBE_SYMBOL(el1_dbg); +static void notrace el1_fpac(struct pt_regs *regs, unsigned long esr) +{ + local_daif_inherit(regs); + do_ptrauth_fault(regs, esr); +} +NOKPROBE_SYMBOL(el1_fpac); + asmlinkage void notrace el1_sync_handler(struct pt_regs *regs) { unsigned long esr = read_sysreg(esr_el1); @@ -92,6 +99,9 @@ asmlinkage void notrace el1_sync_handler(struct pt_regs *regs) case ESR_ELx_EC_BRK64: el1_dbg(regs, esr); break; + case ESR_ELx_EC_FPAC: + el1_fpac(regs, esr); + break; default: el1_inv(regs, esr); } @@ -227,6 +237,14 @@ static void notrace el0_svc(struct pt_regs *regs) } NOKPROBE_SYMBOL(el0_svc); +static void notrace el0_fpac(struct pt_regs *regs, unsigned long esr) +{ + user_exit_irqoff(); + local_daif_restore(DAIF_PROCCTX); + do_ptrauth_fault(regs, esr); +} +NOKPROBE_SYMBOL(el0_fpac); + asmlinkage void notrace el0_sync_handler(struct pt_regs *regs) { unsigned long esr = read_sysreg(esr_el1); @@ -272,6 +290,9 @@ asmlinkage void notrace el0_sync_handler(struct pt_regs *regs) case ESR_ELx_EC_BRK64: el0_dbg(regs, esr); break; + case ESR_ELx_EC_FPAC: + el0_fpac(regs, esr); + break; default: el0_inv(regs, esr); } diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 29fd00fe94f2..b24f81197a68 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -479,6 +479,17 @@ void do_bti(struct pt_regs *regs) } NOKPROBE_SYMBOL(do_bti); +void do_ptrauth_fault(struct pt_regs *regs, unsigned int esr) +{ + /* + * Unexpected FPAC exception or pointer authentication failure in + * the kernel: kill the task before it does any more harm. + */ + BUG_ON(!user_mode(regs)); + force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); +} +NOKPROBE_SYMBOL(do_ptrauth_fault); + #define __user_cache_maint(insn, address, res) \ if (address >= user_addr_max()) { \ res = -EFAULT; \ @@ -775,6 +786,7 @@ static const char *esr_class_str[] = { [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)", [ESR_ELx_EC_SVE] = "SVE", [ESR_ELx_EC_ERET] = "ERET/ERETAA/ERETAB", + [ESR_ELx_EC_FPAC] = "FPAC", [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF", [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)", [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)",