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Mon, 02 Nov 2020 08:05:43 -0800 (PST) Date: Mon, 2 Nov 2020 17:04:12 +0100 In-Reply-To: Message-Id: <9fd49bf636f1f9be56cf400c9ec8afc9b5bc2cfa.1604333009.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.29.1.341.ge80a0c044ae-goog Subject: [PATCH v7 32/41] kasan: introduce CONFIG_KASAN_HW_TAGS From: Andrey Konovalov To: Catalin Marinas , Will Deacon X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201102_110548_091170_F72F505B X-CRM114-Status: GOOD ( 18.10 ) 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: linux-arm-kernel@lists.infradead.org, Marco Elver , Elena Petrova , Andrey Konovalov , Kevin Brodsky , Branislav Rankov , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Alexander Potapenko , Evgenii Stepanov , Andrey Ryabinin , Andrew Morton , Vincenzo Frascino , Dmitry Vyukov Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch adds a configuration option for a new KASAN mode called hardware tag-based KASAN. This mode uses the memory tagging approach like the software tag-based mode, but relies on arm64 Memory Tagging Extension feature for tag management and access checking. Signed-off-by: Andrey Konovalov Co-developed-by: Vincenzo Frascino Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver --- Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe --- lib/Kconfig.kasan | 58 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 41 insertions(+), 17 deletions(-) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index ec59a0e26d09..e5f27ec8b254 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -6,7 +6,10 @@ config HAVE_ARCH_KASAN config HAVE_ARCH_KASAN_SW_TAGS bool -config HAVE_ARCH_KASAN_VMALLOC +config HAVE_ARCH_KASAN_HW_TAGS + bool + +config HAVE_ARCH_KASAN_VMALLOC bool config CC_HAS_KASAN_GENERIC @@ -20,11 +23,11 @@ config CC_HAS_WORKING_NOSANITIZE_ADDRESS menuconfig KASAN bool "KASAN: runtime memory debugger" - depends on (HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ - (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS) + depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ + (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \ + CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ + HAVE_ARCH_KASAN_HW_TAGS depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) - depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS - select CONSTRUCTORS select STACKDEPOT help Enables KASAN (KernelAddressSANitizer) - runtime memory debugger, @@ -37,18 +40,24 @@ choice prompt "KASAN mode" default KASAN_GENERIC help - KASAN has two modes: generic KASAN (similar to userspace ASan, - x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC) and - software tag-based KASAN (a version based on software memory - tagging, arm64 only, similar to userspace HWASan, enabled with - CONFIG_KASAN_SW_TAGS). + KASAN has three modes: + 1. generic KASAN (similar to userspace ASan, + x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC), + 2. software tag-based KASAN (arm64 only, based on software + memory tagging (similar to userspace HWASan), enabled with + CONFIG_KASAN_SW_TAGS), and + 3. hardware tag-based KASAN (arm64 only, based on hardware + memory tagging, enabled with CONFIG_KASAN_HW_TAGS). + + All KASAN modes are strictly debugging features. - Both generic and tag-based KASAN are strictly debugging features. + For better error reports enable CONFIG_STACKTRACE. config KASAN_GENERIC bool "Generic mode" depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC select SLUB_DEBUG if SLUB + select CONSTRUCTORS help Enables generic KASAN mode. @@ -61,8 +70,6 @@ config KASAN_GENERIC and introduces an overhead of ~x1.5 for the rest of the allocations. The performance slowdown is ~x3. - For better error detection enable CONFIG_STACKTRACE. - Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). @@ -70,11 +77,15 @@ config KASAN_SW_TAGS bool "Software tag-based mode" depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS select SLUB_DEBUG if SLUB + select CONSTRUCTORS help Enables software tag-based KASAN mode. - This mode requires Top Byte Ignore support by the CPU and therefore - is only supported for arm64. This mode requires Clang. + This mode require software memory tagging support in the form of + HWASan-like compiler instrumentation. + + Currently this mode is only implemented for arm64 CPUs and relies on + Top Byte Ignore. This mode requires Clang. This mode consumes about 1/16th of available memory at kernel start and introduces an overhead of ~20% for the rest of the allocations. @@ -82,15 +93,27 @@ config KASAN_SW_TAGS casting and comparison, as it embeds tags into the top byte of each pointer. - For better error detection enable CONFIG_STACKTRACE. - Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). +config KASAN_HW_TAGS + bool "Hardware tag-based mode" + depends on HAVE_ARCH_KASAN_HW_TAGS + depends on SLUB + help + Enables hardware tag-based KASAN mode. + + This mode requires hardware memory tagging support, and can be used + by any architecture that provides it. + + Currently this mode is only implemented for arm64 CPUs starting from + ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore. + endchoice choice prompt "Instrumentation type" + depends on KASAN_GENERIC || KASAN_SW_TAGS default KASAN_OUTLINE config KASAN_OUTLINE @@ -114,6 +137,7 @@ endchoice config KASAN_STACK_ENABLE bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST + depends on KASAN_GENERIC || KASAN_SW_TAGS help The LLVM stack address sanitizer has a know problem that causes excessive stack usage in a lot of functions, see