| 1 | # SPDX-License-Identifier: GPL-2.0-only |
| 2 | |
| 3 | # This config refers to the generic KASAN mode. |
| 4 | config HAVE_ARCH_KASAN |
| 5 | bool |
| 6 | |
| 7 | config HAVE_ARCH_KASAN_SW_TAGS |
| 8 | bool |
| 9 | |
| 10 | config HAVE_ARCH_KASAN_HW_TAGS |
| 11 | bool |
| 12 | |
| 13 | config HAVE_ARCH_KASAN_VMALLOC |
| 14 | bool |
| 15 | |
| 16 | config ARCH_DISABLE_KASAN_INLINE |
| 17 | bool |
| 18 | help |
| 19 | Disables both inline and stack instrumentation. Selected by |
| 20 | architectures that do not support these instrumentation types. |
| 21 | |
| 22 | config ARCH_NEEDS_DEFER_KASAN |
| 23 | bool |
| 24 | |
| 25 | config ARCH_DEFER_KASAN |
| 26 | def_bool y |
| 27 | depends on KASAN && ARCH_NEEDS_DEFER_KASAN |
| 28 | help |
| 29 | Architectures should select this if they need to defer KASAN |
| 30 | initialization until shadow memory is properly set up. This |
| 31 | enables runtime control via static keys. Otherwise, KASAN uses |
| 32 | compile-time constants for better performance. |
| 33 | |
| 34 | config CC_HAS_KASAN_GENERIC |
| 35 | def_bool $(cc-option, -fsanitize=kernel-address) |
| 36 | |
| 37 | config CC_HAS_KASAN_SW_TAGS |
| 38 | def_bool $(cc-option, -fsanitize=kernel-hwaddress) |
| 39 | |
| 40 | # This option is only required for software KASAN modes. |
| 41 | # Old GCC versions do not have proper support for no_sanitize_address. |
| 42 | # See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124 for details. |
| 43 | config CC_HAS_WORKING_NOSANITIZE_ADDRESS |
| 44 | def_bool !CC_IS_GCC || GCC_VERSION >= 80300 |
| 45 | |
| 46 | menuconfig KASAN |
| 47 | bool "KASAN: dynamic memory safety error detector" |
| 48 | depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ |
| 49 | (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \ |
| 50 | CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ |
| 51 | HAVE_ARCH_KASAN_HW_TAGS |
| 52 | depends on SYSFS && !SLUB_TINY |
| 53 | select STACKDEPOT_ALWAYS_INIT |
| 54 | help |
| 55 | Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety |
| 56 | error detector designed to find out-of-bounds and use-after-free bugs. |
| 57 | |
| 58 | See Documentation/dev-tools/kasan.rst for details. |
| 59 | |
| 60 | For better error reports, also enable CONFIG_STACKTRACE. |
| 61 | |
| 62 | if KASAN |
| 63 | |
| 64 | config CC_HAS_KASAN_MEMINTRINSIC_PREFIX |
| 65 | def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=kernel-address -mllvm -asan-kernel-mem-intrinsic-prefix=1)) || \ |
| 66 | (CC_IS_GCC && $(cc-option,-fsanitize=kernel-address --param asan-kernel-mem-intrinsic-prefix=1)) |
| 67 | # Don't define it if we don't need it: compilation of the test uses |
| 68 | # this variable to decide how the compiler should treat builtins. |
| 69 | depends on !KASAN_HW_TAGS |
| 70 | help |
| 71 | The compiler is able to prefix memintrinsics with __asan or __hwasan. |
| 72 | |
| 73 | choice |
| 74 | prompt "KASAN mode" |
| 75 | default KASAN_GENERIC |
| 76 | help |
| 77 | KASAN has three modes: |
| 78 | |
| 79 | 1. Generic KASAN (supported by many architectures, enabled with |
| 80 | CONFIG_KASAN_GENERIC, similar to userspace ASan), |
| 81 | 2. Software Tag-Based KASAN (arm64 only, based on software memory |
| 82 | tagging, enabled with CONFIG_KASAN_SW_TAGS, similar to userspace |
| 83 | HWASan), and |
| 84 | 3. Hardware Tag-Based KASAN (arm64 only, based on hardware memory |
| 85 | tagging, enabled with CONFIG_KASAN_HW_TAGS). |
| 86 | |
| 87 | See Documentation/dev-tools/kasan.rst for details about each mode. |
| 88 | |
| 89 | config KASAN_GENERIC |
| 90 | bool "Generic KASAN" |
| 91 | depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC |
| 92 | depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS |
| 93 | select SLUB_DEBUG |
| 94 | select CONSTRUCTORS |
| 95 | help |
| 96 | Enables Generic KASAN. |
| 97 | |
| 98 | Requires GCC 8.3.0+ or Clang. |
| 99 | |
| 100 | Consumes about 1/8th of available memory at kernel start and adds an |
| 101 | overhead of ~50% for dynamic allocations. |
| 102 | The performance slowdown is ~x3. |
| 103 | |
| 104 | config KASAN_SW_TAGS |
| 105 | bool "Software Tag-Based KASAN" |
| 106 | depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS |
| 107 | depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS |
| 108 | select SLUB_DEBUG |
| 109 | select CONSTRUCTORS |
| 110 | help |
| 111 | Enables Software Tag-Based KASAN. |
| 112 | |
| 113 | Requires GCC 11+ or Clang. |
| 114 | |
| 115 | Supported only on arm64 CPUs and relies on Top Byte Ignore. |
| 116 | |
| 117 | Consumes about 1/16th of available memory at kernel start and |
| 118 | add an overhead of ~20% for dynamic allocations. |
| 119 | |
| 120 | May potentially introduce problems related to pointer casting and |
| 121 | comparison, as it embeds a tag into the top byte of each pointer. |
| 122 | |
| 123 | config KASAN_HW_TAGS |
| 124 | bool "Hardware Tag-Based KASAN" |
| 125 | depends on HAVE_ARCH_KASAN_HW_TAGS |
| 126 | help |
| 127 | Enables Hardware Tag-Based KASAN. |
| 128 | |
| 129 | Requires GCC 10+ or Clang 12+. |
| 130 | |
| 131 | Supported only on arm64 CPUs starting from ARMv8.5 and relies on |
| 132 | Memory Tagging Extension and Top Byte Ignore. |
| 133 | |
| 134 | Consumes about 1/32nd of available memory. |
| 135 | |
| 136 | May potentially introduce problems related to pointer casting and |
| 137 | comparison, as it embeds a tag into the top byte of each pointer. |
| 138 | |
| 139 | endchoice |
| 140 | |
| 141 | choice |
| 142 | prompt "Instrumentation type" |
| 143 | depends on KASAN_GENERIC || KASAN_SW_TAGS |
| 144 | default KASAN_INLINE if !ARCH_DISABLE_KASAN_INLINE |
| 145 | |
| 146 | config KASAN_OUTLINE |
| 147 | bool "Outline instrumentation" |
| 148 | help |
| 149 | Makes the compiler insert function calls that check whether the memory |
| 150 | is accessible before each memory access. Slower than KASAN_INLINE, but |
| 151 | does not bloat the size of the kernel's .text section so much. |
| 152 | |
| 153 | config KASAN_INLINE |
| 154 | bool "Inline instrumentation" |
| 155 | depends on !ARCH_DISABLE_KASAN_INLINE |
| 156 | help |
| 157 | Makes the compiler directly insert memory accessibility checks before |
| 158 | each memory access. Faster than KASAN_OUTLINE (gives ~x2 boost for |
| 159 | some workloads), but makes the kernel's .text size much bigger. |
| 160 | |
| 161 | endchoice |
| 162 | |
| 163 | config KASAN_STACK |
| 164 | bool "Stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST |
| 165 | depends on KASAN_GENERIC || KASAN_SW_TAGS |
| 166 | depends on !ARCH_DISABLE_KASAN_INLINE |
| 167 | default y if CC_IS_GCC |
| 168 | help |
| 169 | Disables stack instrumentation and thus KASAN's ability to detect |
| 170 | out-of-bounds bugs in stack variables. |
| 171 | |
| 172 | With Clang, stack instrumentation has a problem that causes excessive |
| 173 | stack usage, see https://llvm.org/pr38809. Thus, |
| 174 | with Clang, this option is deemed unsafe. |
| 175 | |
| 176 | This option is always disabled when compile-testing with Clang to |
| 177 | avoid cluttering the log with stack overflow warnings. |
| 178 | |
| 179 | With GCC, enabling stack instrumentation is assumed to be safe. |
| 180 | |
| 181 | If the architecture disables inline instrumentation via |
| 182 | ARCH_DISABLE_KASAN_INLINE, stack instrumentation gets disabled |
| 183 | as well, as it adds inline-style instrumentation that is run |
| 184 | unconditionally. |
| 185 | |
| 186 | config KASAN_VMALLOC |
| 187 | bool "Check accesses to vmalloc allocations" |
| 188 | depends on HAVE_ARCH_KASAN_VMALLOC |
| 189 | help |
| 190 | Makes KASAN check the validity of accesses to vmalloc allocations. |
| 191 | |
| 192 | With software KASAN modes, all types vmalloc allocations are |
| 193 | checked. Enabling this option leads to higher memory usage. |
| 194 | |
| 195 | With Hardware Tag-Based KASAN, only non-executable VM_ALLOC mappings |
| 196 | are checked. There is no additional memory usage. |
| 197 | |
| 198 | config KASAN_KUNIT_TEST |
| 199 | tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS |
| 200 | depends on KASAN && KUNIT && TRACEPOINTS |
| 201 | default KUNIT_ALL_TESTS |
| 202 | help |
| 203 | A KUnit-based KASAN test suite. Triggers different kinds of |
| 204 | out-of-bounds and use-after-free accesses. Useful for testing whether |
| 205 | KASAN can detect certain bug types. |
| 206 | |
| 207 | For more information on KUnit and unit tests in general, please refer |
| 208 | to the KUnit documentation in Documentation/dev-tools/kunit/. |
| 209 | |
| 210 | config KASAN_EXTRA_INFO |
| 211 | bool "Record and report more information" |
| 212 | depends on KASAN |
| 213 | help |
| 214 | Record and report more information to help us find the cause of the |
| 215 | bug and to help us correlate the error with other system events. |
| 216 | |
| 217 | Currently, the CPU number and timestamp are additionally |
| 218 | recorded for each heap block at allocation and free time, and |
| 219 | 8 bytes will be added to each metadata structure that records |
| 220 | allocation or free information. |
| 221 | |
| 222 | In Generic KASAN, each kmalloc-8 and kmalloc-16 object will add |
| 223 | 16 bytes of additional memory consumption, and each kmalloc-32 |
| 224 | object will add 8 bytes of additional memory consumption, not |
| 225 | affecting other larger objects. |
| 226 | |
| 227 | In SW_TAGS KASAN and HW_TAGS KASAN, depending on the stack_ring_size |
| 228 | boot parameter, it will add 8 * stack_ring_size bytes of additional |
| 229 | memory consumption. |
| 230 | |
| 231 | endif # KASAN |