From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C33971869 for ; Fri, 29 Apr 2022 20:37:38 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id b6-20020a5b0b46000000b006457d921729so8368410ybr.23 for ; Fri, 29 Apr 2022 13:37:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc:content-transfer-encoding; bh=CBFSOSCWmXZdYTn8wlTZ3Rj5NSKYEySXgB9hFZpDWcQ=; b=ZMe9V/MSuwf8udmciH8lqoba83OKO8v0g4K1vzIlxr2talii7K7Ys0ordrrMAHe+pp DaqLObTTros84C3FoilHwVOlv/STu0KhGjugyeK349pAgMRnv4wFfKGXK66cTNEK/E/2 9CS4D6qXyibLUANPFQftw9xg5fy6QMtOA2/GCKenixGS3WyJxUkAAE2Fomn5XE4N6+Fu MH4isN9/BTjRcs0gsnSNZkRVTC/M1BBUGL5BQ+8ljr9lJua+F/PodDy+y3v9FvpxQypS cIBtMTLJxrS2yefnyXe+cpHCAo5gcyjEL1MfDZsZasLEWiGX5qs2r02D/2wLWwBVNFNQ E5nw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc:content-transfer-encoding; bh=CBFSOSCWmXZdYTn8wlTZ3Rj5NSKYEySXgB9hFZpDWcQ=; b=57sQpOammaU46zBdC0rg6T246UY8+leJIHw8BUjjdKm44Ns3VvQS6soWA6dcvrc3Js 5kYOYZpUHFJfbFIzeQ6YgiKCrcA8OnXntCA3XaqzXas4pZt3O/LaivIwBkF8os4SSCai tpdZRpm/J1ZE+O0uDM3fEhKAB2wtl/vqrTr+RLVPJaAnI458AJCj0sCSFgk8wJ+xy0Te i1bHFtPABKbChgvL+v0fEVnlwZ6Tmd31fZTO61TQ6CKUF5TC4PuSPKuk67IzogwUtMM5 QBz3zt3++WjjUS6JhFef50Swo+3QimOTkwjRMYIN6Q9ka9hnqQ7qOt3QCbmj7nLSaYii reMw== X-Gm-Message-State: AOAM530tDos2Simqn4CiPIqbmP4xpmtMn6swLkOFflNyPPpwAzz+AzKT fDdoH7kyw0rtYClhCU+XfqlTr+t3f5JXoYXpRaE= X-Google-Smtp-Source: ABdhPJz3PRZnRDaYveY8PEOrWLh5TwRRZFIgz/hxn66OLDYa/VrKRiT3aho8JsA1WKfUtkL1urGOjyBFCiYVRzF+Yvc= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:351:bea9:f158:1021]) (user=samitolvanen job=sendgmr) by 2002:a25:e0d3:0:b0:645:77c9:4e31 with SMTP id x202-20020a25e0d3000000b0064577c94e31mr1243653ybg.97.1651264657838; Fri, 29 Apr 2022 13:37:37 -0700 (PDT) Date: Fri, 29 Apr 2022 13:36:44 -0700 In-Reply-To: <20220429203644.2868448-1-samitolvanen@google.com> Message-Id: <20220429203644.2868448-22-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20220429203644.2868448-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=3169; h=from:subject; bh=uFL18k3KC4iCKF4AXgGD1Mq4jj5gai1wigbzvC9PP/o=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBibExY2LifXNevk1TsxQ0IeoobF4r0E0uMXfS+2IhA yLd8T56JAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYmxMWAAKCRBMtfaEi7xW7ou7DA CVtuVd3sKEK3z2ChoeiIcGcU8iukBN8OM/HXmzh3pZq6yVg67wrrJiJ5oCCKPR2sRaYP0t6MSn772K l5U4p82O/prDh9AK0kKeyaSy4kvxVMyegTBCTiWzEC3tN48aXVcmI3dMp98RL7LGQzu9v4CLIEVaAa ZyLplEa810jUrIxOZER6sZfDmqUN7V/0ZKKzwsynPVXj76wvte6NCWe3NJ/ZxHTKwz2evdYtezNBOs w5UmruzJ3X4BM+NXqEmVZVfauFH9okVc4aHyl3C0tSJ4hQddWslVlW6jiD7FczG0DVtfhYaktcY3yZ 335Ly2E9sGHsooiWLotHkG2PgPaJ+Jhfa2cw8T3990e55MXFQKaNXNTCRXA+Qq5C7qXBuPFrmbgIz1 isZNNgIYvj+7LUjbO4NBInJYbyLkQMpgNLLqoZq/7hfv1xoJcIZg4CS+1iAmr+3dOxn1GAj/d/7CTi jKj9QZzAlA88rYhDAQ3LbORG2j6VAUCtSo+oWCun3pPF8= X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [RFC PATCH 21/21] x86: Add support for CONFIG_CFI_CLANG From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Add CONFIG_CFI_CLANG error handling and allow the config to be selected on x86_64. Signed-off-by: Sami Tolvanen --- arch/x86/Kconfig | 1 + arch/x86/include/asm/linkage.h | 7 ++++++ arch/x86/kernel/traps.c | 39 +++++++++++++++++++++++++++++++++- 3 files changed, 46 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b0142e01002e..01db5c5c4dde 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -108,6 +108,7 @@ config X86 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <=3D 4096 + select ARCH_SUPPORTS_CFI_CLANG if X86_64 select ARCH_SUPPORTS_LTO_CLANG select ARCH_SUPPORTS_LTO_CLANG_THIN select ARCH_USE_BUILTIN_BSWAP diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.= h index 85865f1645bd..d20acf5ebae3 100644 --- a/arch/x86/include/asm/linkage.h +++ b/arch/x86/include/asm/linkage.h @@ -25,6 +25,13 @@ #define RET ret #endif =20 +#ifdef CONFIG_CFI_CLANG +#define __CFI_TYPE(name) \ + .fill 10, 1, 0x90 ASM_NL \ + .4byte __kcfi_typeid_##name ASM_NL \ + .fill 2, 1, 0xcc +#endif + #else /* __ASSEMBLY__ */ =20 #ifdef CONFIG_SLS diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 1563fb995005..b9e46e6ed83b 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -40,6 +40,7 @@ #include #include #include +#include =20 #include #include @@ -295,6 +296,41 @@ static inline void handle_invalid_op(struct pt_regs *r= egs) ILL_ILLOPN, error_get_trap_addr(regs)); } =20 +#ifdef CONFIG_CFI_CLANG +void *arch_get_cfi_target(unsigned long addr, struct pt_regs *regs) +{ + char buffer[MAX_INSN_SIZE]; + int offset; + struct insn insn; + unsigned long *target; + + /* + * The expected CFI check instruction sequence: + * =C2=A0 cmpl=C2=A0 =C2=A0 , -6(%reg) ; 7 bytes + * je .Ltmp1 ; 2 bytes + * ud2 ; <- addr + * .Ltmp1: + * + * Therefore, the target address is in a register that we can + * decode from the cmpl instruction. + */ + if (copy_from_kernel_nofault(buffer, (void *)addr - 9, MAX_INSN_SIZE)) + return NULL; + if (insn_decode(&insn, buffer, MAX_INSN_SIZE, INSN_MODE_64)) + return NULL; + if (insn.opcode.value !=3D 0x81) + return NULL; + + offset =3D insn_get_modrm_rm_off(&insn, regs); + if (offset < 0) + return NULL; + + target =3D (void *)regs + offset; + + return (void *)*target; +} +#endif + static noinstr bool handle_bug(struct pt_regs *regs) { bool handled =3D false; @@ -312,7 +348,8 @@ static noinstr bool handle_bug(struct pt_regs *regs) */ if (regs->flags & X86_EFLAGS_IF) raw_local_irq_enable(); - if (report_bug(regs->ip, regs) =3D=3D BUG_TRAP_TYPE_WARN) { + if (report_bug(regs->ip, regs) =3D=3D BUG_TRAP_TYPE_WARN || + report_cfi(regs->ip, regs) =3D=3D BUG_TRAP_TYPE_WARN) { regs->ip +=3D LEN_UD2; handled =3D true; } --=20 2.36.0.464.gb9c8b46e94-goog