227 lines
7.5 KiB
Plaintext
227 lines
7.5 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# This config refers to the generic KASAN mode.
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config HAVE_ARCH_KASAN
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bool
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config HAVE_ARCH_KASAN_SW_TAGS
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bool
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config HAVE_ARCH_KASAN_HW_TAGS
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bool
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config HAVE_ARCH_KASAN_VMALLOC
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bool
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config ARCH_DISABLE_KASAN_INLINE
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bool
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help
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Disables both inline and stack instrumentation. Selected by
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architectures that do not support these instrumentation types.
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config CC_HAS_KASAN_GENERIC
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def_bool $(cc-option, -fsanitize=kernel-address)
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config CC_HAS_KASAN_SW_TAGS
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def_bool $(cc-option, -fsanitize=kernel-hwaddress)
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# This option is only required for software KASAN modes.
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# Old GCC versions do not have proper support for no_sanitize_address.
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# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124 for details.
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config CC_HAS_WORKING_NOSANITIZE_ADDRESS
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def_bool !CC_IS_GCC || GCC_VERSION >= 80300
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menuconfig KASAN
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bool "KASAN: dynamic memory safety error detector"
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depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
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(HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \
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CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \
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HAVE_ARCH_KASAN_HW_TAGS
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depends on SYSFS && !SLUB_TINY
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select STACKDEPOT_ALWAYS_INIT
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help
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Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety
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error detector designed to find out-of-bounds and use-after-free bugs.
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See Documentation/dev-tools/kasan.rst for details.
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For better error reports, also enable CONFIG_STACKTRACE.
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if KASAN
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config CC_HAS_KASAN_MEMINTRINSIC_PREFIX
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def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=kernel-address -mllvm -asan-kernel-mem-intrinsic-prefix=1)) || \
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(CC_IS_GCC && $(cc-option,-fsanitize=kernel-address --param asan-kernel-mem-intrinsic-prefix=1))
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# Don't define it if we don't need it: compilation of the test uses
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# this variable to decide how the compiler should treat builtins.
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depends on !KASAN_HW_TAGS
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help
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The compiler is able to prefix memintrinsics with __asan or __hwasan.
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choice
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prompt "KASAN mode"
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default KASAN_GENERIC
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help
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KASAN has three modes:
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1. Generic KASAN (supported by many architectures, enabled with
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CONFIG_KASAN_GENERIC, similar to userspace ASan),
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2. Software Tag-Based KASAN (arm64 only, based on software memory
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tagging, enabled with CONFIG_KASAN_SW_TAGS, similar to userspace
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HWASan), and
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3. Hardware Tag-Based KASAN (arm64 only, based on hardware memory
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tagging, enabled with CONFIG_KASAN_HW_TAGS).
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See Documentation/dev-tools/kasan.rst for details about each mode.
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config KASAN_GENERIC
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bool "Generic KASAN"
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depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
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depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
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select SLUB_DEBUG
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select CONSTRUCTORS
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help
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Enables Generic KASAN.
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Requires GCC 8.3.0+ or Clang.
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Consumes about 1/8th of available memory at kernel start and adds an
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overhead of ~50% for dynamic allocations.
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The performance slowdown is ~x3.
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config KASAN_SW_TAGS
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bool "Software Tag-Based KASAN"
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depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
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depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
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select SLUB_DEBUG
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select CONSTRUCTORS
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help
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Enables Software Tag-Based KASAN.
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Requires GCC 11+ or Clang.
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Supported only on arm64 CPUs and relies on Top Byte Ignore.
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Consumes about 1/16th of available memory at kernel start and
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add an overhead of ~20% for dynamic allocations.
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May potentially introduce problems related to pointer casting and
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comparison, as it embeds a tag into the top byte of each pointer.
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config KASAN_HW_TAGS
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bool "Hardware Tag-Based KASAN"
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depends on HAVE_ARCH_KASAN_HW_TAGS
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help
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Enables Hardware Tag-Based KASAN.
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Requires GCC 10+ or Clang 12+.
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Supported only on arm64 CPUs starting from ARMv8.5 and relies on
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Memory Tagging Extension and Top Byte Ignore.
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Consumes about 1/32nd of available memory.
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May potentially introduce problems related to pointer casting and
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comparison, as it embeds a tag into the top byte of each pointer.
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endchoice
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choice
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prompt "Instrumentation type"
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depends on KASAN_GENERIC || KASAN_SW_TAGS
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default KASAN_INLINE if !ARCH_DISABLE_KASAN_INLINE
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config KASAN_OUTLINE
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bool "Outline instrumentation"
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help
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Makes the compiler insert function calls that check whether the memory
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is accessible before each memory access. Slower than KASAN_INLINE, but
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does not bloat the size of the kernel's .text section so much.
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config KASAN_INLINE
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bool "Inline instrumentation"
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depends on !ARCH_DISABLE_KASAN_INLINE
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help
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Makes the compiler directly insert memory accessibility checks before
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each memory access. Faster than KASAN_OUTLINE (gives ~x2 boost for
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some workloads), but makes the kernel's .text size much bigger.
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endchoice
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config KASAN_STACK
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bool "Stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
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depends on KASAN_GENERIC || KASAN_SW_TAGS
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depends on !ARCH_DISABLE_KASAN_INLINE
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default y if CC_IS_GCC
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help
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Disables stack instrumentation and thus KASAN's ability to detect
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out-of-bounds bugs in stack variables.
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With Clang, stack instrumentation has a problem that causes excessive
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stack usage, see https://llvm.org/pr38809. Thus,
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with Clang, this option is deemed unsafe.
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This option is always disabled when compile-testing with Clang to
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avoid cluttering the log with stack overflow warnings.
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With GCC, enabling stack instrumentation is assumed to be safe.
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If the architecture disables inline instrumentation via
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ARCH_DISABLE_KASAN_INLINE, stack instrumentation gets disabled
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as well, as it adds inline-style instrumentation that is run
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unconditionally.
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config KASAN_VMALLOC
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bool "Check accesses to vmalloc allocations"
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depends on HAVE_ARCH_KASAN_VMALLOC
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help
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Makes KASAN check the validity of accesses to vmalloc allocations.
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With software KASAN modes, all types vmalloc allocations are
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checked. Enabling this option leads to higher memory usage.
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With Hardware Tag-Based KASAN, only non-executable VM_ALLOC mappings
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are checked. There is no additional memory usage.
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config KASAN_KUNIT_TEST
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tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS
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depends on KASAN && KUNIT && TRACEPOINTS
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default KUNIT_ALL_TESTS
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help
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A KUnit-based KASAN test suite. Triggers different kinds of
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out-of-bounds and use-after-free accesses. Useful for testing whether
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KASAN can detect certain bug types.
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For more information on KUnit and unit tests in general, please refer
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to the KUnit documentation in Documentation/dev-tools/kunit/.
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config KASAN_MODULE_TEST
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tristate "KUnit-incompatible tests of KASAN bug detection capabilities"
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depends on m && KASAN && !KASAN_HW_TAGS
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help
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A part of the KASAN test suite that is not integrated with KUnit.
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Incompatible with Hardware Tag-Based KASAN.
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config KASAN_EXTRA_INFO
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bool "Record and report more information"
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depends on KASAN
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help
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Record and report more information to help us find the cause of the
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bug and to help us correlate the error with other system events.
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Currently, the CPU number and timestamp are additionally
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recorded for each heap block at allocation and free time, and
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8 bytes will be added to each metadata structure that records
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allocation or free information.
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In Generic KASAN, each kmalloc-8 and kmalloc-16 object will add
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16 bytes of additional memory consumption, and each kmalloc-32
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object will add 8 bytes of additional memory consumption, not
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affecting other larger objects.
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In SW_TAGS KASAN and HW_TAGS KASAN, depending on the stack_ring_size
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boot parameter, it will add 8 * stack_ring_size bytes of additional
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memory consumption.
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endif # KASAN
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