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ec8f24b7 | 1 | # SPDX-License-Identifier: GPL-2.0-only |
2bd926b4 | 2 | # This config refers to the generic KASAN mode. |
0b24becc AR |
3 | config HAVE_ARCH_KASAN |
4 | bool | |
5 | ||
2bd926b4 AK |
6 | config HAVE_ARCH_KASAN_SW_TAGS |
7 | bool | |
8 | ||
6a63a63f AK |
9 | config HAVE_ARCH_KASAN_HW_TAGS |
10 | bool | |
11 | ||
12 | config HAVE_ARCH_KASAN_VMALLOC | |
3c5c3cfb DA |
13 | bool |
14 | ||
2bd926b4 AK |
15 | config CC_HAS_KASAN_GENERIC |
16 | def_bool $(cc-option, -fsanitize=kernel-address) | |
17 | ||
18 | config CC_HAS_KASAN_SW_TAGS | |
19 | def_bool $(cc-option, -fsanitize=kernel-hwaddress) | |
0b24becc | 20 | |
6a63a63f AK |
21 | # This option is only required for software KASAN modes. |
22 | # Old GCC versions don't have proper support for no_sanitize_address. | |
23 | # See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124 for details. | |
7b861a53 | 24 | config CC_HAS_WORKING_NOSANITIZE_ADDRESS |
acf7b0bf | 25 | def_bool !CC_IS_GCC || GCC_VERSION >= 80300 |
7b861a53 | 26 | |
7a3767f8 | 27 | menuconfig KASAN |
2bd926b4 | 28 | bool "KASAN: runtime memory debugger" |
6a63a63f AK |
29 | depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ |
30 | (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \ | |
31 | CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ | |
32 | HAVE_ARCH_KASAN_HW_TAGS | |
2bd926b4 | 33 | depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) |
ffcc5cea | 34 | select STACKDEPOT |
2bd926b4 AK |
35 | help |
36 | Enables KASAN (KernelAddressSANitizer) - runtime memory debugger, | |
37 | designed to find out-of-bounds accesses and use-after-free bugs. | |
38 | See Documentation/dev-tools/kasan.rst for details. | |
39 | ||
7a3767f8 ME |
40 | if KASAN |
41 | ||
2bd926b4 AK |
42 | choice |
43 | prompt "KASAN mode" | |
2bd926b4 AK |
44 | default KASAN_GENERIC |
45 | help | |
6a63a63f AK |
46 | KASAN has three modes: |
47 | 1. generic KASAN (similar to userspace ASan, | |
48 | x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC), | |
49 | 2. software tag-based KASAN (arm64 only, based on software | |
50 | memory tagging (similar to userspace HWASan), enabled with | |
51 | CONFIG_KASAN_SW_TAGS), and | |
52 | 3. hardware tag-based KASAN (arm64 only, based on hardware | |
53 | memory tagging, enabled with CONFIG_KASAN_HW_TAGS). | |
54 | ||
55 | All KASAN modes are strictly debugging features. | |
ac4766be | 56 | |
6a63a63f | 57 | For better error reports enable CONFIG_STACKTRACE. |
2bd926b4 AK |
58 | |
59 | config KASAN_GENERIC | |
60 | bool "Generic mode" | |
61 | depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC | |
dd275caf | 62 | select SLUB_DEBUG if SLUB |
6a63a63f | 63 | select CONSTRUCTORS |
0b24becc | 64 | help |
2bd926b4 | 65 | Enables generic KASAN mode. |
ac4766be ME |
66 | |
67 | This mode is supported in both GCC and Clang. With GCC it requires | |
527f6750 ME |
68 | version 8.3.0 or later. Any supported Clang version is compatible, |
69 | but detection of out-of-bounds accesses for global variables is | |
70 | supported only since Clang 11. | |
ac4766be | 71 | |
2bd926b4 AK |
72 | This mode consumes about 1/8th of available memory at kernel start |
73 | and introduces an overhead of ~x1.5 for the rest of the allocations. | |
74 | The performance slowdown is ~x3. | |
ac4766be | 75 | |
2bd926b4 | 76 | Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB |
7ed2f9e6 | 77 | (the resulting kernel does not boot). |
0b24becc | 78 | |
2bd926b4 AK |
79 | config KASAN_SW_TAGS |
80 | bool "Software tag-based mode" | |
81 | depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS | |
2bd926b4 | 82 | select SLUB_DEBUG if SLUB |
6a63a63f | 83 | select CONSTRUCTORS |
2bd926b4 AK |
84 | help |
85 | Enables software tag-based KASAN mode. | |
ac4766be | 86 | |
6a63a63f AK |
87 | This mode require software memory tagging support in the form of |
88 | HWASan-like compiler instrumentation. | |
89 | ||
90 | Currently this mode is only implemented for arm64 CPUs and relies on | |
91 | Top Byte Ignore. This mode requires Clang. | |
ac4766be | 92 | |
2bd926b4 AK |
93 | This mode consumes about 1/16th of available memory at kernel start |
94 | and introduces an overhead of ~20% for the rest of the allocations. | |
95 | This mode may potentially introduce problems relating to pointer | |
96 | casting and comparison, as it embeds tags into the top byte of each | |
97 | pointer. | |
ac4766be | 98 | |
2bd926b4 AK |
99 | Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB |
100 | (the resulting kernel does not boot). | |
101 | ||
6a63a63f AK |
102 | config KASAN_HW_TAGS |
103 | bool "Hardware tag-based mode" | |
104 | depends on HAVE_ARCH_KASAN_HW_TAGS | |
105 | depends on SLUB | |
106 | help | |
107 | Enables hardware tag-based KASAN mode. | |
108 | ||
109 | This mode requires hardware memory tagging support, and can be used | |
110 | by any architecture that provides it. | |
111 | ||
112 | Currently this mode is only implemented for arm64 CPUs starting from | |
113 | ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore. | |
114 | ||
2bd926b4 AK |
115 | endchoice |
116 | ||
0b24becc AR |
117 | choice |
118 | prompt "Instrumentation type" | |
6a63a63f | 119 | depends on KASAN_GENERIC || KASAN_SW_TAGS |
0b24becc AR |
120 | default KASAN_OUTLINE |
121 | ||
122 | config KASAN_OUTLINE | |
123 | bool "Outline instrumentation" | |
124 | help | |
125 | Before every memory access compiler insert function call | |
126 | __asan_load*/__asan_store*. These functions performs check | |
127 | of shadow memory. This is slower than inline instrumentation, | |
128 | however it doesn't bloat size of kernel's .text section so | |
129 | much as inline does. | |
130 | ||
131 | config KASAN_INLINE | |
132 | bool "Inline instrumentation" | |
133 | help | |
134 | Compiler directly inserts code checking shadow memory before | |
135 | memory accesses. This is faster than outline (in some workloads | |
136 | it gives about x2 boost over outline instrumentation), but | |
137 | make kernel's .text size much bigger. | |
138 | ||
139 | endchoice | |
140 | ||
6baec880 AB |
141 | config KASAN_STACK_ENABLE |
142 | bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST | |
6a63a63f | 143 | depends on KASAN_GENERIC || KASAN_SW_TAGS |
6baec880 AB |
144 | help |
145 | The LLVM stack address sanitizer has a know problem that | |
146 | causes excessive stack usage in a lot of functions, see | |
147 | https://bugs.llvm.org/show_bug.cgi?id=38809 | |
148 | Disabling asan-stack makes it safe to run kernels build | |
149 | with clang-8 with KASAN enabled, though it loses some of | |
150 | the functionality. | |
ebb6d35a AB |
151 | This feature is always disabled when compile-testing with clang |
152 | to avoid cluttering the output in stack overflow warnings, | |
153 | but clang users can still enable it for builds without | |
154 | CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe | |
155 | to use and enabled by default. | |
6baec880 AB |
156 | |
157 | config KASAN_STACK | |
158 | int | |
159 | default 1 if KASAN_STACK_ENABLE || CC_IS_GCC | |
160 | default 0 | |
161 | ||
ae8f06b3 WW |
162 | config KASAN_SW_TAGS_IDENTIFY |
163 | bool "Enable memory corruption identification" | |
164 | depends on KASAN_SW_TAGS | |
165 | help | |
166 | This option enables best-effort identification of bug type | |
167 | (use-after-free or out-of-bounds) at the cost of increased | |
168 | memory consumption. | |
169 | ||
3c5c3cfb DA |
170 | config KASAN_VMALLOC |
171 | bool "Back mappings in vmalloc space with real shadow memory" | |
71f6af6d | 172 | depends on KASAN_GENERIC && HAVE_ARCH_KASAN_VMALLOC |
3c5c3cfb DA |
173 | help |
174 | By default, the shadow region for vmalloc space is the read-only | |
175 | zero page. This means that KASAN cannot detect errors involving | |
176 | vmalloc space. | |
177 | ||
178 | Enabling this option will hook in to vmap/vmalloc and back those | |
179 | mappings with real shadow memory allocated on demand. This allows | |
180 | for KASAN to detect more sorts of errors (and to support vmapped | |
181 | stacks), but at the cost of higher memory usage. | |
182 | ||
73228c7e PA |
183 | config KASAN_KUNIT_TEST |
184 | tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS | |
185 | depends on KASAN && KUNIT | |
186 | default KUNIT_ALL_TESTS | |
3f15801c | 187 | help |
73228c7e PA |
188 | This is a KUnit test suite doing various nasty things like |
189 | out of bounds and use after free accesses. It is useful for testing | |
2bd926b4 | 190 | kernel debugging features like KASAN. |
7a3767f8 | 191 | |
73228c7e | 192 | For more information on KUnit and unit tests in general, please refer |
f05842cf | 193 | to the KUnit documentation in Documentation/dev-tools/kunit. |
73228c7e | 194 | |
5d92bdff | 195 | config KASAN_MODULE_TEST |
73228c7e | 196 | tristate "KUnit-incompatible tests of KASAN bug detection capabilities" |
f05842cf | 197 | depends on m && KASAN && !KASAN_HW_TAGS |
73228c7e PA |
198 | help |
199 | This is a part of the KASAN test suite that is incompatible with | |
200 | KUnit. Currently includes tests that do bad copy_from/to_user | |
201 | accesses. | |
202 | ||
7a3767f8 | 203 | endif # KASAN |