hc
2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c
kernel/lib/Kconfig.kasan
....@@ -1,8 +1,15 @@
1
+# SPDX-License-Identifier: GPL-2.0-only
12 # This config refers to the generic KASAN mode.
23 config HAVE_ARCH_KASAN
34 bool
45
56 config HAVE_ARCH_KASAN_SW_TAGS
7
+ bool
8
+
9
+config HAVE_ARCH_KASAN_HW_TAGS
10
+ bool
11
+
12
+config HAVE_ARCH_KASAN_VMALLOC
613 bool
714
815 config CC_HAS_KASAN_GENERIC
....@@ -11,76 +18,107 @@
1118 config CC_HAS_KASAN_SW_TAGS
1219 def_bool $(cc-option, -fsanitize=kernel-hwaddress)
1320
14
-config KASAN
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.
24
+config CC_HAS_WORKING_NOSANITIZE_ADDRESS
25
+ def_bool !CC_IS_GCC || GCC_VERSION >= 80300
26
+
27
+menuconfig KASAN
1528 bool "KASAN: runtime memory debugger"
16
- depends on (HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
17
- (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)
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
1833 depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
34
+ select STACKDEPOT
1935 help
2036 Enables KASAN (KernelAddressSANitizer) - runtime memory debugger,
2137 designed to find out-of-bounds accesses and use-after-free bugs.
2238 See Documentation/dev-tools/kasan.rst for details.
2339
40
+if KASAN
41
+
2442 choice
2543 prompt "KASAN mode"
26
- depends on KASAN
2744 default KASAN_GENERIC
2845 help
29
- KASAN has two modes: generic KASAN (similar to userspace ASan,
30
- x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC) and
31
- software tag-based KASAN (a version based on software memory
32
- tagging, arm64 only, similar to userspace HWASan, enabled with
33
- CONFIG_KASAN_SW_TAGS).
34
- Both generic and tag-based KASAN are strictly debugging features.
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).
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+
55
+ All KASAN modes are strictly debugging features.
56
+
57
+ For better error reports enable CONFIG_STACKTRACE.
3558
3659 config KASAN_GENERIC
3760 bool "Generic mode"
3861 depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
39
- depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
62
+ depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
4063 select SLUB_DEBUG if SLUB
4164 select CONSTRUCTORS
42
- select STACKDEPOT
4365 help
4466 Enables generic KASAN mode.
45
- Supported in both GCC and Clang. With GCC it requires version 4.9.2
46
- or later for basic support and version 5.0 or later for detection of
47
- out-of-bounds accesses for stack and global variables and for inline
48
- instrumentation mode (CONFIG_KASAN_INLINE). With Clang it requires
49
- version 3.7.0 or later and it doesn't support detection of
50
- out-of-bounds accesses for global variables yet.
67
+
68
+ This mode is supported in both GCC and Clang. With GCC it requires
69
+ version 8.3.0 or later. Any supported Clang version is compatible,
70
+ but detection of out-of-bounds accesses for global variables is
71
+ supported only since Clang 11.
72
+
5173 This mode consumes about 1/8th of available memory at kernel start
5274 and introduces an overhead of ~x1.5 for the rest of the allocations.
5375 The performance slowdown is ~x3.
54
- For better error detection enable CONFIG_STACKTRACE.
76
+
5577 Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
5678 (the resulting kernel does not boot).
5779
5880 config KASAN_SW_TAGS
5981 bool "Software tag-based mode"
6082 depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
61
- depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
83
+ depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
6284 select SLUB_DEBUG if SLUB
6385 select CONSTRUCTORS
64
- select STACKDEPOT
6586 help
6687 Enables software tag-based KASAN mode.
67
- This mode requires Top Byte Ignore support by the CPU and therefore
68
- is only supported for arm64.
69
- This mode requires Clang version 7.0.0 or later.
88
+
89
+ This mode require software memory tagging support in the form of
90
+ HWASan-like compiler instrumentation.
91
+
92
+ Currently this mode is only implemented for arm64 CPUs and relies on
93
+ Top Byte Ignore. This mode requires Clang.
94
+
7095 This mode consumes about 1/16th of available memory at kernel start
7196 and introduces an overhead of ~20% for the rest of the allocations.
7297 This mode may potentially introduce problems relating to pointer
7398 casting and comparison, as it embeds tags into the top byte of each
7499 pointer.
75
- For better error detection enable CONFIG_STACKTRACE.
100
+
76101 Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB
77102 (the resulting kernel does not boot).
103
+
104
+config KASAN_HW_TAGS
105
+ bool "Hardware tag-based mode"
106
+ depends on HAVE_ARCH_KASAN_HW_TAGS
107
+ depends on SLUB
108
+ help
109
+ Enables hardware tag-based KASAN mode.
110
+
111
+ This mode requires hardware memory tagging support, and can be used
112
+ by any architecture that provides it.
113
+
114
+ Currently this mode is only implemented for arm64 CPUs starting from
115
+ ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore.
78116
79117 endchoice
80118
81119 choice
82120 prompt "Instrumentation type"
83
- depends on KASAN
121
+ depends on KASAN_GENERIC || KASAN_SW_TAGS
84122 default KASAN_OUTLINE
85123
86124 config KASAN_OUTLINE
....@@ -99,13 +137,13 @@
99137 memory accesses. This is faster than outline (in some workloads
100138 it gives about x2 boost over outline instrumentation), but
101139 make kernel's .text size much bigger.
102
- For CONFIG_KASAN_GENERIC this requires GCC 5.0 or later.
103140
104141 endchoice
105142
106
-config KASAN_STACK_ENABLE
143
+config KASAN_STACK
107144 bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
108
- depends on KASAN
145
+ depends on KASAN_GENERIC || KASAN_SW_TAGS
146
+ default y if CC_IS_GCC
109147 help
110148 The LLVM stack address sanitizer has a know problem that
111149 causes excessive stack usage in a lot of functions, see
....@@ -119,15 +157,54 @@
119157 CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe
120158 to use and enabled by default.
121159
122
-config KASAN_STACK
123
- int
124
- default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
125
- default 0
126
-
127
-config TEST_KASAN
128
- tristate "Module for testing KASAN for bug detection"
129
- depends on m && KASAN
160
+config KASAN_S390_4_LEVEL_PAGING
161
+ bool "KASan: use 4-level paging"
162
+ depends on S390
130163 help
131
- This is a test module doing various nasty things like
132
- out of bounds accesses, use after free. It is useful for testing
164
+ Compiling the kernel with KASan disables automatic 3-level vs
165
+ 4-level paging selection. 3-level paging is used by default (up
166
+ to 3TB of RAM with KASan enabled). This options allows to force
167
+ 4-level paging instead.
168
+
169
+config KASAN_SW_TAGS_IDENTIFY
170
+ bool "Enable memory corruption identification"
171
+ depends on KASAN_SW_TAGS
172
+ help
173
+ This option enables best-effort identification of bug type
174
+ (use-after-free or out-of-bounds) at the cost of increased
175
+ memory consumption.
176
+
177
+config KASAN_VMALLOC
178
+ bool "Back mappings in vmalloc space with real shadow memory"
179
+ depends on KASAN_GENERIC && HAVE_ARCH_KASAN_VMALLOC
180
+ help
181
+ By default, the shadow region for vmalloc space is the read-only
182
+ zero page. This means that KASAN cannot detect errors involving
183
+ vmalloc space.
184
+
185
+ Enabling this option will hook in to vmap/vmalloc and back those
186
+ mappings with real shadow memory allocated on demand. This allows
187
+ for KASAN to detect more sorts of errors (and to support vmapped
188
+ stacks), but at the cost of higher memory usage.
189
+
190
+config KASAN_KUNIT_TEST
191
+ tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS
192
+ depends on KASAN && KUNIT
193
+ default KUNIT_ALL_TESTS
194
+ help
195
+ This is a KUnit test suite doing various nasty things like
196
+ out of bounds and use after free accesses. It is useful for testing
133197 kernel debugging features like KASAN.
198
+
199
+ For more information on KUnit and unit tests in general, please refer
200
+ to the KUnit documentation in Documentation/dev-tools/kunit.
201
+
202
+config KASAN_MODULE_TEST
203
+ tristate "KUnit-incompatible tests of KASAN bug detection capabilities"
204
+ depends on m && KASAN && !KASAN_HW_TAGS
205
+ help
206
+ This is a part of the KASAN test suite that is incompatible with
207
+ KUnit. Currently includes tests that do bad copy_from/to_user
208
+ accesses.
209
+
210
+endif # KASAN