Linux/security/Kconfig.hardening

Version: ~ [ linux-6.12-rc7 ] ~ [ linux-6.11.7 ] ~ [ linux-6.10.14 ] ~ [ linux-6.9.12 ] ~ [ linux-6.8.12 ] ~ [ linux-6.7.12 ] ~ [ linux-6.6.60 ] ~ [ linux-6.5.13 ] ~ [ linux-6.4.16 ] ~ [ linux-6.3.13 ] ~ [ linux-6.2.16 ] ~ [ linux-6.1.116 ] ~ [ linux-6.0.19 ] ~ [ linux-5.19.17 ] ~ [ linux-5.18.19 ] ~ [ linux-5.17.15 ] ~ [ linux-5.16.20 ] ~ [ linux-5.15.171 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.229 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.285 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.323 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.336 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.337 ] ~ [ linux-4.4.302 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.12 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only 2 menu "Kernel hardening options" 2 menu "Kernel hardening options" 3 3 4 config GCC_PLUGIN_STRUCTLEAK 4 config GCC_PLUGIN_STRUCTLEAK 5 bool 5 bool 6 help 6 help 7 While the kernel is built with warni 7 While the kernel is built with warnings enabled for any missed 8 stack variable initializations, this 8 stack variable initializations, this warning is silenced for 9 anything passed by reference to anot 9 anything passed by reference to another function, under the 10 occasionally misguided assumption th 10 occasionally misguided assumption that the function will do 11 the initialization. As this regularl 11 the initialization. As this regularly leads to exploitable 12 flaws, this plugin is available to i 12 flaws, this plugin is available to identify and zero-initialize 13 such variables, depending on the cho 13 such variables, depending on the chosen level of coverage. 14 14 15 This plugin was originally ported fr 15 This plugin was originally ported from grsecurity/PaX. More 16 information at: 16 information at: 17 * https://grsecurity.net/ 17 * https://grsecurity.net/ 18 * https://pax.grsecurity.net/ 18 * https://pax.grsecurity.net/ 19 19 20 menu "Memory initialization" 20 menu "Memory initialization" 21 21 22 config CC_HAS_AUTO_VAR_INIT_PATTERN !! 22 config CC_HAS_AUTO_VAR_INIT 23 def_bool $(cc-option,-ftrivial-auto-va 23 def_bool $(cc-option,-ftrivial-auto-var-init=pattern) 24 24 25 config CC_HAS_AUTO_VAR_INIT_ZERO_BARE << 26 def_bool $(cc-option,-ftrivial-auto-va << 27 << 28 config CC_HAS_AUTO_VAR_INIT_ZERO_ENABLER << 29 # Clang 16 and later warn about using << 30 # is required before then. << 31 def_bool $(cc-option,-ftrivial-auto-va << 32 depends on !CC_HAS_AUTO_VAR_INIT_ZERO_ << 33 << 34 config CC_HAS_AUTO_VAR_INIT_ZERO << 35 def_bool CC_HAS_AUTO_VAR_INIT_ZERO_BAR << 36 << 37 choice 25 choice 38 prompt "Initialize kernel stack variab 26 prompt "Initialize kernel stack variables at function entry" 39 default GCC_PLUGIN_STRUCTLEAK_BYREF_AL 27 default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS 40 default INIT_STACK_ALL_PATTERN if COMP !! 28 default INIT_STACK_ALL if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT 41 default INIT_STACK_ALL_ZERO if CC_HAS_ << 42 default INIT_STACK_NONE 29 default INIT_STACK_NONE 43 help 30 help 44 This option enables initialization o 31 This option enables initialization of stack variables at 45 function entry time. This has the po 32 function entry time. This has the possibility to have the 46 greatest coverage (since all functio 33 greatest coverage (since all functions can have their 47 variables initialized), but the perf 34 variables initialized), but the performance impact depends 48 on the function calling complexity o 35 on the function calling complexity of a given workload's 49 syscalls. 36 syscalls. 50 37 51 This chooses the level of coverage o 38 This chooses the level of coverage over classes of potentially 52 uninitialized variables. The selecte !! 39 uninitialized variables. The selected class will be 53 initialized before use in a function 40 initialized before use in a function. 54 41 55 config INIT_STACK_NONE 42 config INIT_STACK_NONE 56 bool "no automatic stack varia !! 43 bool "no automatic initialization (weakest)" 57 help 44 help 58 Disable automatic stack vari 45 Disable automatic stack variable initialization. 59 This leaves the kernel vulne 46 This leaves the kernel vulnerable to the standard 60 classes of uninitialized sta 47 classes of uninitialized stack variable exploits 61 and information exposures. 48 and information exposures. 62 49 63 config GCC_PLUGIN_STRUCTLEAK_USER 50 config GCC_PLUGIN_STRUCTLEAK_USER 64 bool "zero-init structs marked 51 bool "zero-init structs marked for userspace (weak)" 65 # Plugin can be removed once t !! 52 depends on GCC_PLUGINS 66 depends on GCC_PLUGINS && !CC_ << 67 select GCC_PLUGIN_STRUCTLEAK 53 select GCC_PLUGIN_STRUCTLEAK 68 help 54 help 69 Zero-initialize any structur 55 Zero-initialize any structures on the stack containing 70 a __user attribute. This can 56 a __user attribute. This can prevent some classes of 71 uninitialized stack variable 57 uninitialized stack variable exploits and information 72 exposures, like CVE-2013-214 58 exposures, like CVE-2013-2141: 73 https://git.kernel.org/linus 59 https://git.kernel.org/linus/b9e146d8eb3b9eca 74 60 75 config GCC_PLUGIN_STRUCTLEAK_BYREF 61 config GCC_PLUGIN_STRUCTLEAK_BYREF 76 bool "zero-init structs passed 62 bool "zero-init structs passed by reference (strong)" 77 # Plugin can be removed once t !! 63 depends on GCC_PLUGINS 78 depends on GCC_PLUGINS && !CC_ !! 64 depends on !(KASAN && KASAN_STACK=1) 79 depends on !(KASAN && KASAN_ST << 80 select GCC_PLUGIN_STRUCTLEAK 65 select GCC_PLUGIN_STRUCTLEAK 81 help 66 help 82 Zero-initialize any structur 67 Zero-initialize any structures on the stack that may 83 be passed by reference and h 68 be passed by reference and had not already been 84 explicitly initialized. This 69 explicitly initialized. This can prevent most classes 85 of uninitialized stack varia 70 of uninitialized stack variable exploits and information 86 exposures, like CVE-2017-100 71 exposures, like CVE-2017-1000410: 87 https://git.kernel.org/linus 72 https://git.kernel.org/linus/06e7e776ca4d3654 88 73 89 As a side-effect, this keeps 74 As a side-effect, this keeps a lot of variables on the 90 stack that can otherwise be 75 stack that can otherwise be optimized out, so combining 91 this with CONFIG_KASAN_STACK 76 this with CONFIG_KASAN_STACK can lead to a stack overflow 92 and is disallowed. 77 and is disallowed. 93 78 94 config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL 79 config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL 95 bool "zero-init everything pas !! 80 bool "zero-init anything passed by reference (very strong)" 96 # Plugin can be removed once t !! 81 depends on GCC_PLUGINS 97 depends on GCC_PLUGINS && !CC_ !! 82 depends on !(KASAN && KASAN_STACK=1) 98 depends on !(KASAN && KASAN_ST << 99 select GCC_PLUGIN_STRUCTLEAK 83 select GCC_PLUGIN_STRUCTLEAK 100 help 84 help 101 Zero-initialize any stack va 85 Zero-initialize any stack variables that may be passed 102 by reference and had not alr 86 by reference and had not already been explicitly 103 initialized. This is intende 87 initialized. This is intended to eliminate all classes 104 of uninitialized stack varia 88 of uninitialized stack variable exploits and information 105 exposures. 89 exposures. 106 90 107 As a side-effect, this keeps !! 91 config INIT_STACK_ALL 108 stack that can otherwise be !! 92 bool "0xAA-init everything on the stack (strongest)" 109 this with CONFIG_KASAN_STACK !! 93 depends on CC_HAS_AUTO_VAR_INIT 110 and is disallowed. << 111 << 112 config INIT_STACK_ALL_PATTERN << 113 bool "pattern-init everything << 114 depends on CC_HAS_AUTO_VAR_INI << 115 depends on !KMSAN << 116 help << 117 Initializes everything on th << 118 with a specific debug value. << 119 all classes of uninitialized << 120 information exposures, even << 121 having been left uninitializ << 122 << 123 Pattern initialization is kn << 124 related to uninitialized loc << 125 non-NULL values, buffer size << 126 pattern is situation-specifi << 127 repeating for all types and << 128 which use 0xFF repeating (-N << 129 repeating for all types and << 130 << 131 config INIT_STACK_ALL_ZERO << 132 bool "zero-init everything (st << 133 depends on CC_HAS_AUTO_VAR_INI << 134 depends on !KMSAN << 135 help 94 help 136 Initializes everything on th !! 95 Initializes everything on the stack with a 0xAA 137 with a zero value. This is i !! 96 pattern. This is intended to eliminate all classes 138 classes of uninitialized sta !! 97 of uninitialized stack variable exploits and information 139 information exposures, even !! 98 exposures, even variables that were warned to have been 140 about having been left unini !! 99 left uninitialized. 141 << 142 Zero initialization provides << 143 (immediately NUL-terminated) << 144 (index 0), and sizes (0 leng << 145 suitable as a production sec << 146 initialization. << 147 100 148 endchoice 101 endchoice 149 102 150 config GCC_PLUGIN_STRUCTLEAK_VERBOSE 103 config GCC_PLUGIN_STRUCTLEAK_VERBOSE 151 bool "Report forcefully initialized va 104 bool "Report forcefully initialized variables" 152 depends on GCC_PLUGIN_STRUCTLEAK 105 depends on GCC_PLUGIN_STRUCTLEAK 153 depends on !COMPILE_TEST # too 106 depends on !COMPILE_TEST # too noisy 154 help 107 help 155 This option will cause a warning to 108 This option will cause a warning to be printed each time the 156 structleak plugin finds a variable i 109 structleak plugin finds a variable it thinks needs to be 157 initialized. Since not all existing 110 initialized. Since not all existing initializers are detected 158 by the plugin, this can produce fals 111 by the plugin, this can produce false positive warnings. 159 112 160 config GCC_PLUGIN_STACKLEAK 113 config GCC_PLUGIN_STACKLEAK 161 bool "Poison kernel stack before retur 114 bool "Poison kernel stack before returning from syscalls" 162 depends on GCC_PLUGINS 115 depends on GCC_PLUGINS 163 depends on HAVE_ARCH_STACKLEAK 116 depends on HAVE_ARCH_STACKLEAK 164 help 117 help 165 This option makes the kernel erase t 118 This option makes the kernel erase the kernel stack before 166 returning from system calls. This ha 119 returning from system calls. This has the effect of leaving 167 the stack initialized to the poison 120 the stack initialized to the poison value, which both reduces 168 the lifetime of any sensitive stack 121 the lifetime of any sensitive stack contents and reduces 169 potential for uninitialized stack va 122 potential for uninitialized stack variable exploits or information 170 exposures (it does not cover functio 123 exposures (it does not cover functions reaching the same stack 171 depth as prior functions during the 124 depth as prior functions during the same syscall). This blocks 172 most uninitialized stack variable at 125 most uninitialized stack variable attacks, with the performance 173 impact being driven by the depth of 126 impact being driven by the depth of the stack usage, rather than 174 the function calling complexity. 127 the function calling complexity. 175 128 176 The performance impact on a single C 129 The performance impact on a single CPU system kernel compilation 177 sees a 1% slowdown, other systems an 130 sees a 1% slowdown, other systems and workloads may vary and you 178 are advised to test this feature on 131 are advised to test this feature on your expected workload before 179 deploying it. 132 deploying it. 180 133 181 This plugin was ported from grsecuri 134 This plugin was ported from grsecurity/PaX. More information at: 182 * https://grsecurity.net/ 135 * https://grsecurity.net/ 183 * https://pax.grsecurity.net/ 136 * https://pax.grsecurity.net/ 184 137 185 config GCC_PLUGIN_STACKLEAK_VERBOSE << 186 bool "Report stack depth analysis inst << 187 depends on GCC_PLUGIN_STACKLEAK << 188 depends on !COMPILE_TEST # too << 189 help << 190 This option will cause a warning to << 191 stackleak plugin finds a function it << 192 instrumented. This is useful for com << 193 builds. << 194 << 195 config STACKLEAK_TRACK_MIN_SIZE 138 config STACKLEAK_TRACK_MIN_SIZE 196 int "Minimum stack frame size of funct 139 int "Minimum stack frame size of functions tracked by STACKLEAK" 197 default 100 140 default 100 198 range 0 4096 141 range 0 4096 199 depends on GCC_PLUGIN_STACKLEAK 142 depends on GCC_PLUGIN_STACKLEAK 200 help 143 help 201 The STACKLEAK gcc plugin instruments 144 The STACKLEAK gcc plugin instruments the kernel code for tracking 202 the lowest border of the kernel stac 145 the lowest border of the kernel stack (and for some other purposes). 203 It inserts the stackleak_track_stack 146 It inserts the stackleak_track_stack() call for the functions with 204 a stack frame size greater than or e 147 a stack frame size greater than or equal to this parameter. 205 If unsure, leave the default value 1 148 If unsure, leave the default value 100. 206 149 207 config STACKLEAK_METRICS 150 config STACKLEAK_METRICS 208 bool "Show STACKLEAK metrics in the /p 151 bool "Show STACKLEAK metrics in the /proc file system" 209 depends on GCC_PLUGIN_STACKLEAK 152 depends on GCC_PLUGIN_STACKLEAK 210 depends on PROC_FS 153 depends on PROC_FS 211 help 154 help 212 If this is set, STACKLEAK metrics fo 155 If this is set, STACKLEAK metrics for every task are available in 213 the /proc file system. In particular 156 the /proc file system. In particular, /proc/<pid>/stack_depth 214 shows the maximum kernel stack consu 157 shows the maximum kernel stack consumption for the current and 215 previous syscalls. Although this inf 158 previous syscalls. Although this information is not precise, it 216 can be useful for estimating the STA 159 can be useful for estimating the STACKLEAK performance impact for 217 your workloads. 160 your workloads. 218 161 219 config STACKLEAK_RUNTIME_DISABLE 162 config STACKLEAK_RUNTIME_DISABLE 220 bool "Allow runtime disabling of kerne 163 bool "Allow runtime disabling of kernel stack erasing" 221 depends on GCC_PLUGIN_STACKLEAK 164 depends on GCC_PLUGIN_STACKLEAK 222 help 165 help 223 This option provides 'stack_erasing' 166 This option provides 'stack_erasing' sysctl, which can be used in 224 runtime to control kernel stack eras 167 runtime to control kernel stack erasing for kernels built with 225 CONFIG_GCC_PLUGIN_STACKLEAK. 168 CONFIG_GCC_PLUGIN_STACKLEAK. 226 169 227 config INIT_ON_ALLOC_DEFAULT_ON 170 config INIT_ON_ALLOC_DEFAULT_ON 228 bool "Enable heap memory zeroing on al 171 bool "Enable heap memory zeroing on allocation by default" 229 depends on !KMSAN << 230 help 172 help 231 This has the effect of setting "init 173 This has the effect of setting "init_on_alloc=1" on the kernel 232 command line. This can be disabled w 174 command line. This can be disabled with "init_on_alloc=0". 233 When "init_on_alloc" is enabled, all 175 When "init_on_alloc" is enabled, all page allocator and slab 234 allocator memory will be zeroed when 176 allocator memory will be zeroed when allocated, eliminating 235 many kinds of "uninitialized heap me 177 many kinds of "uninitialized heap memory" flaws, especially 236 heap content exposures. The performa 178 heap content exposures. The performance impact varies by 237 workload, but most cases see <1% imp 179 workload, but most cases see <1% impact. Some synthetic 238 workloads have measured as high as 7 180 workloads have measured as high as 7%. 239 181 240 config INIT_ON_FREE_DEFAULT_ON 182 config INIT_ON_FREE_DEFAULT_ON 241 bool "Enable heap memory zeroing on fr 183 bool "Enable heap memory zeroing on free by default" 242 depends on !KMSAN << 243 help 184 help 244 This has the effect of setting "init 185 This has the effect of setting "init_on_free=1" on the kernel 245 command line. This can be disabled w 186 command line. This can be disabled with "init_on_free=0". 246 Similar to "init_on_alloc", when "in 187 Similar to "init_on_alloc", when "init_on_free" is enabled, 247 all page allocator and slab allocato 188 all page allocator and slab allocator memory will be zeroed 248 when freed, eliminating many kinds o 189 when freed, eliminating many kinds of "uninitialized heap memory" 249 flaws, especially heap content expos 190 flaws, especially heap content exposures. The primary difference 250 with "init_on_free" is that data lif 191 with "init_on_free" is that data lifetime in memory is reduced, 251 as anything freed is wiped immediate 192 as anything freed is wiped immediately, making live forensics or 252 cold boot memory attacks unable to r 193 cold boot memory attacks unable to recover freed memory contents. 253 The performance impact varies by wor 194 The performance impact varies by workload, but is more expensive 254 than "init_on_alloc" due to the nega 195 than "init_on_alloc" due to the negative cache effects of 255 touching "cold" memory areas. Most c 196 touching "cold" memory areas. Most cases see 3-5% impact. Some 256 synthetic workloads have measured as 197 synthetic workloads have measured as high as 8%. 257 198 258 config CC_HAS_ZERO_CALL_USED_REGS << 259 def_bool $(cc-option,-fzero-call-used- << 260 # https://github.com/ClangBuiltLinux/l << 261 # https://github.com/llvm/llvm-project << 262 depends on !CC_IS_CLANG || CLANG_VERSI << 263 << 264 config ZERO_CALL_USED_REGS << 265 bool "Enable register zeroing on funct << 266 depends on CC_HAS_ZERO_CALL_USED_REGS << 267 help << 268 At the end of functions, always zero << 269 contents. This helps ensure that tem << 270 leaked beyond the function boundary. << 271 contents are less likely to be avail << 272 and information exposures. Additiona << 273 number of useful ROP gadgets by abou << 274 generated "write-what-where" gadgets << 275 image. This has a less than 1% perfo << 276 workloads. Image size growth depends << 277 be evaluated for suitability. For ex << 278 than 1%, and arm64 grows by about 5% << 279 << 280 endmenu 199 endmenu 281 << 282 menu "Hardening of kernel data structures" << 283 << 284 config LIST_HARDENED << 285 bool "Check integrity of linked list m << 286 help << 287 Minimal integrity checking in the li << 288 to catch memory corruptions that are << 289 immediate access fault. << 290 << 291 If unsure, say N. << 292 << 293 config BUG_ON_DATA_CORRUPTION << 294 bool "Trigger a BUG when data corrupti << 295 select LIST_HARDENED << 296 help << 297 Select this option if the kernel sho << 298 data corruption in kernel memory str << 299 for validity. << 300 << 301 If unsure, say N. << 302 << 303 endmenu << 304 << 305 config CC_HAS_RANDSTRUCT << 306 def_bool $(cc-option,-frandomize-layou << 307 # Randstruct was first added in Clang << 308 # Clang 16 due to https://github.com/l << 309 depends on !CC_IS_CLANG || CLANG_VERSI << 310 << 311 choice << 312 prompt "Randomize layout of sensitive << 313 default RANDSTRUCT_FULL if COMPILE_TES << 314 default RANDSTRUCT_NONE << 315 help << 316 If you enable this, the layouts of s << 317 function pointers (and have not been << 318 __no_randomize_layout), or structure << 319 marked with __randomize_layout, will << 320 This can introduce the requirement o << 321 exposure vulnerability for exploits << 322 types. << 323 << 324 Enabling this feature will introduce << 325 slightly increase memory usage, and << 326 tools like Volatility against the sy << 327 source tree isn't cleaned after kern << 328 << 329 The seed used for compilation is in << 330 It remains after a "make clean" to a << 331 be compiled with the existing seed a << 332 "make mrproper" or "make distclean". << 333 public, or the structure layout can << 334 << 335 config RANDSTRUCT_NONE << 336 bool "Disable structure layout << 337 help << 338 Build normally: no structure << 339 << 340 config RANDSTRUCT_FULL << 341 bool "Fully randomize structur << 342 depends on CC_HAS_RANDSTRUCT | << 343 select MODVERSIONS if MODULES << 344 help << 345 Fully randomize the member l << 346 structures as much as possib << 347 memory size and performance << 348 << 349 One difference between the C << 350 implementations is the handl << 351 plugin treats them as fully << 352 introducing sometimes signif << 353 to keep adjacent bitfields t << 354 ordering randomized. << 355 << 356 config RANDSTRUCT_PERFORMANCE << 357 bool "Limit randomization of s << 358 depends on GCC_PLUGINS << 359 select MODVERSIONS if MODULES << 360 help << 361 Randomization of sensitive k << 362 best effort at restricting r << 363 groups of members. It will f << 364 in structures. This reduces << 365 at the cost of weakened rand << 366 endchoice << 367 << 368 config RANDSTRUCT << 369 def_bool !RANDSTRUCT_NONE << 370 << 371 config GCC_PLUGIN_RANDSTRUCT << 372 def_bool GCC_PLUGINS && RANDSTRUCT << 373 help << 374 Use GCC plugin to randomize structur << 375 << 376 This plugin was ported from grsecuri << 377 information at: << 378 * https://grsecurity.net/ << 379 * https://pax.grsecurity.net/ << 380 200 381 endmenu 201 endmenu

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TOMOYO Linux Cross Reference
Linux/security/Kconfig.hardening

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Differences between /security/Kconfig.hardening (Version linux-6.12-rc7) and /security/Kconfig.hardening (Version linux-5.6.19)

TOMOYO Linux Cross Reference Linux/security/Kconfig.hardening

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Differences between /security/Kconfig.hardening (Version linux-6.12-rc7) and /security/Kconfig.hardening (Version linux-5.6.19)

TOMOYO Linux Cross Reference
Linux/security/Kconfig.hardening