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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=7T2c0bl5OkkQ79Gbe1n87t+HukBdE3TTJ/DXUdpKX6g=; b=X7b2gBpvNntzerImGfGaeF538t/ObYXmH2DiMC8+yTcAjGVwoEpTmw13j7kATriQKU gDHoPRLISBnO/OfZOh0dBbv4j5Ic1tL30dGlLiY4yE+g5Orrsg09T480QR9DsrlAOq2g a2YIca5HfbW8ZaL+quFqIUtb/Am/pvLRU4tvAmfNnfkZRQPo2xdlybWg4cUXuobOtYro TOGjHtj79w1KXauRvqirRPmrgF5+lxqcqC7kc21EoJlmUGzMQmvzEzzo/ztlSr9PX7Hg ZOhnTB4sME8FApwTnXKo8n9TSCaIJ2wVN8MwdHyJSR7w3d6zCOg0FZjXivrXI3Ju6WEy sVUQ== X-Gm-Message-State: AOAM531R3bwBKhUg8y1QhbxP+aa3ZMvDoLoC/B2OTC1XY3P9nj9neQnT uAO5rPnsSPChaTU7ViSFW7ZtWRSv0/B9 X-Google-Smtp-Source: ABdhPJwMSp/rAEOX2pa/XWlA4huWXhXIwFC1NziSv58q8T8Af4FW8ptK4uG0CBbmUC48wraFdMIWN6oOpPNq X-Received: from jiancai.svl.corp.google.com ([2620:15c:2ce:0:6578:8d7f:50d0:55c8]) (user=jiancai job=sendgmr) by 2002:a0c:c488:: with SMTP id u8mr3180406qvi.9.1613765935591; Fri, 19 Feb 2021 12:18:55 -0800 (PST) Date: Fri, 19 Feb 2021 12:18:40 -0800 In-Reply-To: <20210212195255.1321544-1-jiancai@google.com> Message-Id: <20210219201852.3213914-1-jiancai@google.com> Mime-Version: 1.0 References: <20210212195255.1321544-1-jiancai@google.com> X-Mailer: git-send-email 2.30.0.617.g56c4b15f3c-goog Subject: [PATCH v3] ARM: Implement SLS mitigation From: Jian Cai X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210219_151900_380265_4130A915 X-CRM114-Status: GOOD ( 16.65 ) 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 , Catalin Marinas , James Morris , manojgupta@google.com, Will Deacon , Ingo Molnar , Marc Zyngier , Masahiro Yamada , Russell King , Ard Biesheuvel , clang-built-linux@googlegroups.com, llozano@google.com, David Brazdil , "Serge E. Hallyn" , Kees Cook , Arnd Bergmann , Jian Cai , Nathan Chancellor , linux-arm-kernel@lists.infradead.org, ndesaulniers@google.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, David Laight , James Morse , Olof Johansson , Andrew Morton , =?utf-8?q?Andreas_F=C3=A4rber?= , Mike Rapoport Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch adds CONFIG_HARDEN_SLS_ALL that can be used to turn on -mharden-sls=all, which mitigates the straight-line speculation vulnerability, speculative execution of the instruction following some unconditional jumps. Notice -mharden-sls= has other options as below, and this config turns on the strongest option. all: enable all mitigations against Straight Line Speculation that are implemented. none: disable all mitigations against Straight Line Speculation. retbr: enable the mitigation against Straight Line Speculation for RET and BR instructions. blr: enable the mitigation against Straight Line Speculation for BLR instructions. Links: https://reviews.llvm.org/D93221 https://reviews.llvm.org/D81404 https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/downloads/straight-line-speculation https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/frequently-asked-questions#SLS2 Suggested-by: Manoj Gupta Suggested-by: Nick Desaulniers Suggested-by: Nathan Chancellor Suggested-by: David Laight Suggested-by: Will Deacon Reviewed-by: Nathan Chancellor Signed-off-by: Jian Cai --- Changes v2 -> v3: Modify linker scripts as Nick suggested to address boot failure (verified with qemu). Added more details in Kconfig.hardening description. Disable the config by default. arch/arm/Makefile | 4 ++++ arch/arm/include/asm/vmlinux.lds.h | 4 ++++ arch/arm/kernel/vmlinux.lds.S | 1 + arch/arm64/Makefile | 4 ++++ arch/arm64/kernel/vmlinux.lds.S | 5 +++++ security/Kconfig.hardening | 10 ++++++++++ 6 files changed, 28 insertions(+) diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 4aaec9599e8a..11d89ef32da9 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -48,6 +48,10 @@ CHECKFLAGS += -D__ARMEL__ KBUILD_LDFLAGS += -EL endif +ifeq ($(CONFIG_HARDEN_SLS_ALL), y) +KBUILD_CFLAGS += -mharden-sls=all +endif + # # The Scalar Replacement of Aggregates (SRA) optimization pass in GCC 4.9 and # later may result in code being generated that handles signed short and signed diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h index 4a91428c324d..c7f9717511ca 100644 --- a/arch/arm/include/asm/vmlinux.lds.h +++ b/arch/arm/include/asm/vmlinux.lds.h @@ -145,3 +145,7 @@ __edtcm_data = .; \ } \ . = __dtcm_start + SIZEOF(.data_dtcm); + +#define SLS_TEXT \ + ALIGN_FUNCTION(); \ + *(.text.__llvm_slsblr_thunk_*) diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index f7f4620d59c3..e71f2bc97bae 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -63,6 +63,7 @@ SECTIONS .text : { /* Real text segment */ _stext = .; /* Text and read-only data */ ARM_TEXT + SLS_TEXT } #ifdef CONFIG_DEBUG_ALIGN_RODATA diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 90309208bb28..ca7299b356a9 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -34,6 +34,10 @@ $(warning LSE atomics not supported by binutils) endif endif +ifeq ($(CONFIG_HARDEN_SLS_ALL), y) +KBUILD_CFLAGS += -mharden-sls=all +endif + cc_has_k_constraint := $(call try-run,echo \ 'int main(void) { \ asm volatile("and w0, w0, %w0" :: "K" (4294967295)); \ diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 4c0b0c89ad59..f8912e42ffcd 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -93,6 +93,10 @@ jiffies = jiffies_64; #define TRAMP_TEXT #endif +#define SLS_TEXT \ + ALIGN_FUNCTION(); \ + *(.text.__llvm_slsblr_thunk_*) + /* * The size of the PE/COFF section that covers the kernel image, which * runs from _stext to _edata, must be a round multiple of the PE/COFF @@ -144,6 +148,7 @@ SECTIONS HIBERNATE_TEXT TRAMP_TEXT *(.fixup) + SLS_TEXT *(.gnu.warning) . = ALIGN(16); *(.got) /* Global offset table */ diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index 269967c4fc1b..e70f227019e1 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -121,6 +121,16 @@ choice endchoice +config HARDEN_SLS_ALL + bool "enable SLS vulnerability hardening" + default n + def_bool $(cc-option,-mharden-sls=all) + help + Enables straight-line speculation vulnerability hardening on ARM and ARM64 + architectures. It inserts speculation barrier sequences (SB or DSB+ISB + depending on the target architecture) after RET and BR, and replacing + BLR with BL+BR sequence. + config GCC_PLUGIN_STRUCTLEAK_VERBOSE bool "Report forcefully initialized variables" depends on GCC_PLUGIN_STRUCTLEAK