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Diffstat (limited to 'lib/Kconfig.kasan')
| -rw-r--r-- | lib/Kconfig.kasan | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan new file mode 100644 index 000000000..542a9c183 --- /dev/null +++ b/lib/Kconfig.kasan @@ -0,0 +1,189 @@ +# SPDX-License-Identifier: GPL-2.0-only +# This config refers to the generic KASAN mode. +config HAVE_ARCH_KASAN + bool + +config HAVE_ARCH_KASAN_SW_TAGS + bool + +config HAVE_ARCH_KASAN_VMALLOC + bool + +config CC_HAS_KASAN_GENERIC + def_bool $(cc-option, -fsanitize=kernel-address) + +config CC_HAS_KASAN_SW_TAGS + def_bool $(cc-option, -fsanitize=kernel-hwaddress) + +config CC_HAS_WORKING_NOSANITIZE_ADDRESS + def_bool !CC_IS_GCC || GCC_VERSION >= 80300 + +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 (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) + depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS + help + Enables KASAN (KernelAddressSANitizer) - runtime memory debugger, + designed to find out-of-bounds accesses and use-after-free bugs. + See Documentation/dev-tools/kasan.rst for details. + +if KASAN + +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). + + Both generic and tag-based KASAN are strictly debugging features. + +config KASAN_GENERIC + bool "Generic mode" + depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC + depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) + select SLUB_DEBUG if SLUB + select CONSTRUCTORS + select STACKDEPOT + help + Enables generic KASAN mode. + + This mode is supported in both GCC and Clang. With GCC it requires + version 8.3.0 or later. Any supported Clang version is compatible, + but detection of out-of-bounds accesses for global variables is + supported only since Clang 11. + + This mode consumes about 1/8th of available memory at kernel start + 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). + +config KASAN_SW_TAGS + bool "Software tag-based mode" + depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS + depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) + select SLUB_DEBUG if SLUB + select CONSTRUCTORS + select STACKDEPOT + 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 consumes about 1/16th of available memory at kernel start + and introduces an overhead of ~20% for the rest of the allocations. + This mode may potentially introduce problems relating to pointer + 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). + +endchoice + +choice + prompt "Instrumentation type" + default KASAN_OUTLINE + +config KASAN_OUTLINE + bool "Outline instrumentation" + help + Before every memory access compiler insert function call + __asan_load*/__asan_store*. These functions performs check + of shadow memory. This is slower than inline instrumentation, + however it doesn't bloat size of kernel's .text section so + much as inline does. + +config KASAN_INLINE + bool "Inline instrumentation" + help + Compiler directly inserts code checking shadow memory before + memory accesses. This is faster than outline (in some workloads + it gives about x2 boost over outline instrumentation), but + make kernel's .text size much bigger. + +endchoice + +config KASAN_STACK_ENABLE + bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST + help + The LLVM stack address sanitizer has a know problem that + causes excessive stack usage in a lot of functions, see + https://bugs.llvm.org/show_bug.cgi?id=38809 + Disabling asan-stack makes it safe to run kernels build + with clang-8 with KASAN enabled, though it loses some of + the functionality. + This feature is always disabled when compile-testing with clang + to avoid cluttering the output in stack overflow warnings, + but clang users can still enable it for builds without + CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe + to use and enabled by default. + +config KASAN_STACK + int + default 1 if KASAN_STACK_ENABLE || CC_IS_GCC + default 0 + +config KASAN_S390_4_LEVEL_PAGING + bool "KASan: use 4-level paging" + depends on S390 + help + Compiling the kernel with KASan disables automatic 3-level vs + 4-level paging selection. 3-level paging is used by default (up + to 3TB of RAM with KASan enabled). This options allows to force + 4-level paging instead. + +config KASAN_SW_TAGS_IDENTIFY + bool "Enable memory corruption identification" + depends on KASAN_SW_TAGS + help + This option enables best-effort identification of bug type + (use-after-free or out-of-bounds) at the cost of increased + memory consumption. + +config KASAN_VMALLOC + bool "Back mappings in vmalloc space with real shadow memory" + depends on HAVE_ARCH_KASAN_VMALLOC + help + By default, the shadow region for vmalloc space is the read-only + zero page. This means that KASAN cannot detect errors involving + vmalloc space. + + Enabling this option will hook in to vmap/vmalloc and back those + mappings with real shadow memory allocated on demand. This allows + for KASAN to detect more sorts of errors (and to support vmapped + stacks), but at the cost of higher memory usage. + +config KASAN_KUNIT_TEST + tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS + depends on KASAN && KUNIT + default KUNIT_ALL_TESTS + help + This is a KUnit test suite doing various nasty things like + out of bounds and use after free accesses. It is useful for testing + kernel debugging features like KASAN. + + For more information on KUnit and unit tests in general, please refer + to the KUnit documentation in Documentation/dev-tools/kunit + +config TEST_KASAN_MODULE + tristate "KUnit-incompatible tests of KASAN bug detection capabilities" + depends on m && KASAN + help + This is a part of the KASAN test suite that is incompatible with + KUnit. Currently includes tests that do bad copy_from/to_user + accesses. + +endif # KASAN |