1 # kconfig-hardened-check
3 
4 
5 [](https://codecov.io/gh/a13xp0p0v/kconfig-hardened-check)
9 There are plenty of security hardening options for the Linux kernel. A lot of them are
10 not enabled by the major distros. We have to enable these options ourselves to
11 make our systems more secure.
13 But nobody likes checking configs manually. So let the computers do their job!
15 __kconfig-hardened-check__ helps me to check the Linux kernel options
16 against my security hardening preferences, which are based on the
18 - [KSPP recommended settings][1]
19 - [CLIP OS kernel configuration][2]
20 - Last public [grsecurity][3] patch (options which they disable)
21 - [SECURITY_LOCKDOWN_LSM][5] patchset
22 - [Direct feedback from the Linux kernel maintainers][23]
24 This tool supports checking __Kconfig__ options and __kernel cmdline__ parameters.
26 I also created the [__Linux Kernel Defence Map__][4], which is a graphical representation of the
27 relationships between security hardening features and the corresponding vulnerability classes
28 or exploitation techniques.
30 __Attention!__ Changing Linux kernel security parameters may also affect system performance
31 and functionality of userspace software. So for choosing these parameters consider
32 the threat model of your Linux-based information system and perform thorough testing
33 of its typical workload.
37 - At Codeberg: [https://codeberg.org/a13xp0p0v/kconfig-hardened-check](https://codeberg.org/a13xp0p0v/kconfig-hardened-check)
38 - At GitFlic: [https://gitflic.ru/project/a13xp0p0v/kconfig-hardened-check](https://gitflic.ru/project/a13xp0p0v/kconfig-hardened-check)
40 ## Supported microarchitectures
47 TODO: RISC-V (issue [#56][22])
51 You can install the package:
54 pip install git+https://github.com/a13xp0p0v/kconfig-hardened-check
57 or simply run `./bin/kconfig-hardened-check` from the cloned repository.
59 Some Linux distributions also provide `kconfig-hardened-check` as a package.
63 usage: kconfig-hardened-check [-h] [--version] [-p {X86_64,X86_32,ARM64,ARM}]
66 [-m {verbose,json,show_ok,show_fail}]
68 A tool for checking the security hardening options of the Linux kernel
71 -h, --help show this help message and exit
72 --version show program's version number and exit
73 -p {X86_64,X86_32,ARM64,ARM}, --print {X86_64,X86_32,ARM64,ARM}
74 print security hardening preferences for the selected architecture
75 -c CONFIG, --config CONFIG
76 check the kernel kconfig file against these preferences
77 -l CMDLINE, --cmdline CMDLINE
78 check the kernel cmdline file against these preferences
79 -m {verbose,json,show_ok,show_fail}, --mode {verbose,json,show_ok,show_fail}
80 choose the report mode
85 - no `-m` argument for the default output mode (see the example below)
86 - `-m verbose` for printing additional info:
87 - config options without a corresponding check
88 - internals of complex checks with AND/OR, like this:
90 -------------------------------------------------------------------------------------------
92 CONFIG_STRICT_DEVMEM | y |defconfig | cut_attack_surface
93 CONFIG_DEVMEM | is not set | kspp | cut_attack_surface
94 -------------------------------------------------------------------------------------------
96 - `-m show_fail` for showing only the failed checks
97 - `-m show_ok` for showing only the successful checks
98 - `-m json` for printing the results in JSON format (for combining `kconfig-hardened-check` with other tools)
100 ## Example output for `Fedora 34` kernel configuration
102 $ ./bin/kconfig-hardened-check -c /boot/config-5.19.14-200.fc36.x86_64 -l /proc/cmdline
103 [+] Kconfig file to check: /boot/config-5.19.14-200.fc36.x86_64
104 [+] Kernel cmdline file to check: /proc/cmdline
105 [+] Detected architecture: X86_64
106 [+] Detected kernel version: 5.19
107 [+] Detected compiler: GCC 120201
108 =========================================================================================================================
109 option name | type |desired val | decision | reason | check result
110 =========================================================================================================================
111 CONFIG_BUG |kconfig| y |defconfig | self_protection | OK
112 CONFIG_SLUB_DEBUG |kconfig| y |defconfig | self_protection | OK
113 CONFIG_GCC_PLUGINS |kconfig| y |defconfig | self_protection | OK
114 CONFIG_STACKPROTECTOR |kconfig| y |defconfig | self_protection | OK
115 CONFIG_STACKPROTECTOR_STRONG |kconfig| y |defconfig | self_protection | FAIL: "is not set"
116 CONFIG_STRICT_KERNEL_RWX |kconfig| y |defconfig | self_protection | OK
117 CONFIG_STRICT_MODULE_RWX |kconfig| y |defconfig | self_protection | OK
118 CONFIG_REFCOUNT_FULL |kconfig| y |defconfig | self_protection | OK: version >= 5.5
119 CONFIG_THREAD_INFO_IN_TASK |kconfig| y |defconfig | self_protection | OK
120 CONFIG_IOMMU_SUPPORT |kconfig| y |defconfig | self_protection | OK
121 CONFIG_RANDOMIZE_BASE |kconfig| y |defconfig | self_protection | OK
122 CONFIG_VMAP_STACK |kconfig| y |defconfig | self_protection | OK
123 CONFIG_X86_MCE |kconfig| y |defconfig | self_protection | OK
124 CONFIG_X86_MCE_INTEL |kconfig| y |defconfig | self_protection | OK
125 CONFIG_X86_MCE_AMD |kconfig| y |defconfig | self_protection | OK
126 CONFIG_MICROCODE |kconfig| y |defconfig | self_protection | OK
127 CONFIG_RETPOLINE |kconfig| y |defconfig | self_protection | OK
128 CONFIG_X86_SMAP |kconfig| y |defconfig | self_protection | OK: version >= 5.19
129 CONFIG_SYN_COOKIES |kconfig| y |defconfig | self_protection | OK
130 CONFIG_X86_UMIP |kconfig| y |defconfig | self_protection | OK
131 CONFIG_PAGE_TABLE_ISOLATION |kconfig| y |defconfig | self_protection | OK
132 CONFIG_RANDOMIZE_MEMORY |kconfig| y |defconfig | self_protection | OK
133 CONFIG_INTEL_IOMMU |kconfig| y |defconfig | self_protection | OK
134 CONFIG_AMD_IOMMU |kconfig| y |defconfig | self_protection | OK
135 CONFIG_BUG_ON_DATA_CORRUPTION |kconfig| y | kspp | self_protection | OK
136 CONFIG_DEBUG_WX |kconfig| y | kspp | self_protection | OK
137 CONFIG_SCHED_STACK_END_CHECK |kconfig| y | kspp | self_protection | OK
138 CONFIG_SLAB_FREELIST_HARDENED |kconfig| y | kspp | self_protection | OK
139 CONFIG_SLAB_FREELIST_RANDOM |kconfig| y | kspp | self_protection | OK
140 CONFIG_SHUFFLE_PAGE_ALLOCATOR |kconfig| y | kspp | self_protection | OK
141 CONFIG_FORTIFY_SOURCE |kconfig| y | kspp | self_protection | OK
142 CONFIG_DEBUG_LIST |kconfig| y | kspp | self_protection | OK
143 CONFIG_DEBUG_VIRTUAL |kconfig| y | kspp | self_protection | FAIL: "is not set"
144 CONFIG_DEBUG_SG |kconfig| y | kspp | self_protection | FAIL: "is not set"
145 CONFIG_DEBUG_CREDENTIALS |kconfig| y | kspp | self_protection | FAIL: "is not set"
146 CONFIG_DEBUG_NOTIFIERS |kconfig| y | kspp | self_protection | FAIL: "is not set"
147 CONFIG_INIT_ON_ALLOC_DEFAULT_ON |kconfig| y | kspp | self_protection | FAIL: "is not set"
148 CONFIG_GCC_PLUGIN_LATENT_ENTROPY |kconfig| y | kspp | self_protection | FAIL: "is not set"
149 CONFIG_KFENCE |kconfig| y | kspp | self_protection | OK
150 CONFIG_WERROR |kconfig| y | kspp | self_protection | FAIL: "is not set"
151 CONFIG_IOMMU_DEFAULT_DMA_STRICT |kconfig| y | kspp | self_protection | FAIL: "is not set"
152 CONFIG_IOMMU_DEFAULT_PASSTHROUGH |kconfig| is not set | kspp | self_protection | OK
153 CONFIG_ZERO_CALL_USED_REGS |kconfig| y | kspp | self_protection | FAIL: "is not set"
154 CONFIG_HW_RANDOM_TPM |kconfig| y | kspp | self_protection | OK
155 CONFIG_STATIC_USERMODEHELPER |kconfig| y | kspp | self_protection | FAIL: "is not set"
156 CONFIG_SCHED_CORE |kconfig| y | kspp | self_protection | OK
157 CONFIG_RANDSTRUCT_FULL |kconfig| y | kspp | self_protection | FAIL: "is not set"
158 CONFIG_RANDSTRUCT_PERFORMANCE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_RANDSTRUCT_FULL not "y"
159 CONFIG_HARDENED_USERCOPY |kconfig| y | kspp | self_protection | OK
160 CONFIG_HARDENED_USERCOPY_FALLBACK |kconfig| is not set | kspp | self_protection | OK: not found
161 CONFIG_HARDENED_USERCOPY_PAGESPAN |kconfig| is not set | kspp | self_protection | OK: not found
162 CONFIG_MODULE_SIG |kconfig| y | kspp | self_protection | OK
163 CONFIG_MODULE_SIG_ALL |kconfig| y | kspp | self_protection | OK
164 CONFIG_MODULE_SIG_SHA512 |kconfig| y | kspp | self_protection | OK
165 CONFIG_MODULE_SIG_FORCE |kconfig| y | kspp | self_protection | FAIL: "is not set"
166 CONFIG_INIT_STACK_ALL_ZERO |kconfig| y | kspp | self_protection | FAIL: "is not set"
167 CONFIG_INIT_ON_FREE_DEFAULT_ON |kconfig| y | kspp | self_protection | FAIL: "is not set"
168 CONFIG_EFI_DISABLE_PCI_DMA |kconfig| y | kspp | self_protection | FAIL: "is not set"
169 CONFIG_RESET_ATTACK_MITIGATION |kconfig| y | kspp | self_protection | FAIL: "is not set"
170 CONFIG_UBSAN_BOUNDS |kconfig| y | kspp | self_protection | FAIL: not found
171 CONFIG_UBSAN_LOCAL_BOUNDS |kconfig| y | kspp | self_protection | FAIL: not found
172 CONFIG_UBSAN_TRAP |kconfig| y | kspp | self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
173 CONFIG_UBSAN_SANITIZE_ALL |kconfig| y | kspp | self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
174 CONFIG_GCC_PLUGIN_STACKLEAK |kconfig| y | kspp | self_protection | FAIL: "is not set"
175 CONFIG_STACKLEAK_METRICS |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
176 CONFIG_STACKLEAK_RUNTIME_DISABLE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
177 CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT |kconfig| y | kspp | self_protection | OK
178 CONFIG_CFI_CLANG |kconfig| y | kspp | self_protection | FAIL: not found
179 CONFIG_CFI_PERMISSIVE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_CFI_CLANG not "y"
180 CONFIG_DEFAULT_MMAP_MIN_ADDR |kconfig| 65536 | kspp | self_protection | OK
181 CONFIG_INTEL_IOMMU_DEFAULT_ON |kconfig| y | kspp | self_protection | FAIL: "is not set"
182 CONFIG_SLS |kconfig| y | kspp | self_protection | OK
183 CONFIG_INTEL_IOMMU_SVM |kconfig| y | kspp | self_protection | OK
184 CONFIG_AMD_IOMMU_V2 |kconfig| y | kspp | self_protection | FAIL: "m"
185 CONFIG_SLAB_MERGE_DEFAULT |kconfig| is not set | clipos | self_protection | OK
186 CONFIG_SECURITY |kconfig| y |defconfig | security_policy | OK
187 CONFIG_SECURITY_YAMA |kconfig| y | kspp | security_policy | OK
188 CONFIG_SECURITY_LANDLOCK |kconfig| y | kspp | security_policy | OK
189 CONFIG_SECURITY_SELINUX_DISABLE |kconfig| is not set | kspp | security_policy | OK
190 CONFIG_SECURITY_SELINUX_BOOTPARAM |kconfig| is not set | kspp | security_policy | FAIL: "y"
191 CONFIG_SECURITY_SELINUX_DEVELOP |kconfig| is not set | kspp | security_policy | FAIL: "y"
192 CONFIG_SECURITY_LOCKDOWN_LSM |kconfig| y | kspp | security_policy | OK
193 CONFIG_SECURITY_LOCKDOWN_LSM_EARLY |kconfig| y | kspp | security_policy | OK
194 CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY|kconfig| y | kspp | security_policy | FAIL: "is not set"
195 CONFIG_SECURITY_WRITABLE_HOOKS |kconfig| is not set | kspp | security_policy | OK: not found
196 CONFIG_BPF_UNPRIV_DEFAULT_OFF |kconfig| y |defconfig |cut_attack_surface| OK
197 CONFIG_SECCOMP |kconfig| y |defconfig |cut_attack_surface| OK
198 CONFIG_SECCOMP_FILTER |kconfig| y |defconfig |cut_attack_surface| OK
199 CONFIG_STRICT_DEVMEM |kconfig| y |defconfig |cut_attack_surface| OK
200 CONFIG_SECURITY_DMESG_RESTRICT |kconfig| y | kspp |cut_attack_surface| FAIL: "is not set"
201 CONFIG_ACPI_CUSTOM_METHOD |kconfig| is not set | kspp |cut_attack_surface| OK
202 CONFIG_COMPAT_BRK |kconfig| is not set | kspp |cut_attack_surface| OK
203 CONFIG_DEVKMEM |kconfig| is not set | kspp |cut_attack_surface| OK: not found
204 CONFIG_COMPAT_VDSO |kconfig| is not set | kspp |cut_attack_surface| OK
205 CONFIG_BINFMT_MISC |kconfig| is not set | kspp |cut_attack_surface| FAIL: "m"
206 CONFIG_INET_DIAG |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
207 CONFIG_KEXEC |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
208 CONFIG_PROC_KCORE |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
209 CONFIG_LEGACY_PTYS |kconfig| is not set | kspp |cut_attack_surface| OK
210 CONFIG_HIBERNATION |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
211 CONFIG_IA32_EMULATION |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
212 CONFIG_X86_X32 |kconfig| is not set | kspp |cut_attack_surface| OK: not found
213 CONFIG_MODIFY_LDT_SYSCALL |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
214 CONFIG_OABI_COMPAT |kconfig| is not set | kspp |cut_attack_surface| OK: not found
215 CONFIG_X86_MSR |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
216 CONFIG_MODULES |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
217 CONFIG_DEVMEM |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
218 CONFIG_IO_STRICT_DEVMEM |kconfig| y | kspp |cut_attack_surface| OK
219 CONFIG_LDISC_AUTOLOAD |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
220 CONFIG_LEGACY_VSYSCALL_NONE |kconfig| y | kspp |cut_attack_surface| FAIL: "is not set"
221 CONFIG_ZSMALLOC_STAT |kconfig| is not set | grsec |cut_attack_surface| OK
222 CONFIG_PAGE_OWNER |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
223 CONFIG_DEBUG_KMEMLEAK |kconfig| is not set | grsec |cut_attack_surface| OK
224 CONFIG_BINFMT_AOUT |kconfig| is not set | grsec |cut_attack_surface| OK: not found
225 CONFIG_KPROBE_EVENTS |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
226 CONFIG_UPROBE_EVENTS |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
227 CONFIG_GENERIC_TRACER |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
228 CONFIG_FUNCTION_TRACER |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
229 CONFIG_STACK_TRACER |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
230 CONFIG_HIST_TRIGGERS |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
231 CONFIG_BLK_DEV_IO_TRACE |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
232 CONFIG_PROC_VMCORE |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
233 CONFIG_PROC_PAGE_MONITOR |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
234 CONFIG_USELIB |kconfig| is not set | grsec |cut_attack_surface| OK
235 CONFIG_CHECKPOINT_RESTORE |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
236 CONFIG_USERFAULTFD |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
237 CONFIG_HWPOISON_INJECT |kconfig| is not set | grsec |cut_attack_surface| FAIL: "m"
238 CONFIG_MEM_SOFT_DIRTY |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
239 CONFIG_DEVPORT |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
240 CONFIG_DEBUG_FS |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
241 CONFIG_NOTIFIER_ERROR_INJECTION |kconfig| is not set | grsec |cut_attack_surface| OK
242 CONFIG_FAIL_FUTEX |kconfig| is not set | grsec |cut_attack_surface| OK: not found
243 CONFIG_PUNIT_ATOM_DEBUG |kconfig| is not set | grsec |cut_attack_surface| OK
244 CONFIG_ACPI_CONFIGFS |kconfig| is not set | grsec |cut_attack_surface| OK
245 CONFIG_EDAC_DEBUG |kconfig| is not set | grsec |cut_attack_surface| OK
246 CONFIG_DRM_I915_DEBUG |kconfig| is not set | grsec |cut_attack_surface| OK: not found
247 CONFIG_BCACHE_CLOSURES_DEBUG |kconfig| is not set | grsec |cut_attack_surface| OK
248 CONFIG_DVB_C8SECTPFE |kconfig| is not set | grsec |cut_attack_surface| OK: not found
249 CONFIG_MTD_SLRAM |kconfig| is not set | grsec |cut_attack_surface| OK
250 CONFIG_MTD_PHRAM |kconfig| is not set | grsec |cut_attack_surface| OK
251 CONFIG_IO_URING |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
252 CONFIG_KCMP |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
253 CONFIG_RSEQ |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
254 CONFIG_LATENCYTOP |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
255 CONFIG_KCOV |kconfig| is not set | grsec |cut_attack_surface| OK
256 CONFIG_PROVIDE_OHCI1394_DMA_INIT |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
257 CONFIG_SUNRPC_DEBUG |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
258 CONFIG_PTDUMP_DEBUGFS |kconfig| is not set | grsec |cut_attack_surface| OK
259 CONFIG_DRM_LEGACY |kconfig| is not set |maintainer|cut_attack_surface| OK
260 CONFIG_FB |kconfig| is not set |maintainer|cut_attack_surface| FAIL: "y"
261 CONFIG_VT |kconfig| is not set |maintainer|cut_attack_surface| FAIL: "y"
262 CONFIG_BLK_DEV_FD |kconfig| is not set |maintainer|cut_attack_surface| FAIL: "m"
263 CONFIG_BLK_DEV_FD_RAWCMD |kconfig| is not set |maintainer|cut_attack_surface| OK
264 CONFIG_AIO |kconfig| is not set |grapheneos|cut_attack_surface| FAIL: "y"
265 CONFIG_STAGING |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
266 CONFIG_KSM |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
267 CONFIG_KALLSYMS |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
268 CONFIG_X86_VSYSCALL_EMULATION |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
269 CONFIG_MAGIC_SYSRQ |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
270 CONFIG_KEXEC_FILE |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
271 CONFIG_USER_NS |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
272 CONFIG_X86_CPUID |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
273 CONFIG_X86_IOPL_IOPERM |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
274 CONFIG_ACPI_TABLE_UPGRADE |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
275 CONFIG_EFI_CUSTOM_SSDT_OVERLAYS |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
276 CONFIG_COREDUMP |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
277 CONFIG_X86_INTEL_TSX_MODE_OFF |kconfig| y | clipos |cut_attack_surface| OK
278 CONFIG_BPF_SYSCALL |kconfig| is not set | lockdown |cut_attack_surface| FAIL: "y"
279 CONFIG_EFI_TEST |kconfig| is not set | lockdown |cut_attack_surface| FAIL: "m"
280 CONFIG_MMIOTRACE_TEST |kconfig| is not set | lockdown |cut_attack_surface| OK
281 CONFIG_KPROBES |kconfig| is not set | lockdown |cut_attack_surface| FAIL: "y"
282 CONFIG_TRIM_UNUSED_KSYMS |kconfig| y | my |cut_attack_surface| FAIL: not found
283 CONFIG_MMIOTRACE |kconfig| is not set | my |cut_attack_surface| FAIL: "y"
284 CONFIG_LIVEPATCH |kconfig| is not set | my |cut_attack_surface| FAIL: "y"
285 CONFIG_IP_DCCP |kconfig| is not set | my |cut_attack_surface| OK
286 CONFIG_IP_SCTP |kconfig| is not set | my |cut_attack_surface| FAIL: "m"
287 CONFIG_FTRACE |kconfig| is not set | my |cut_attack_surface| FAIL: "y"
288 CONFIG_VIDEO_VIVID |kconfig| is not set | my |cut_attack_surface| OK: not found
289 CONFIG_INPUT_EVBUG |kconfig| is not set | my |cut_attack_surface| OK
290 CONFIG_KGDB |kconfig| is not set | my |cut_attack_surface| FAIL: "y"
291 CONFIG_INTEGRITY |kconfig| y |defconfig | harden_userspace | OK
292 CONFIG_ARCH_MMAP_RND_BITS |kconfig| 32 | clipos | harden_userspace | FAIL: "28"
293 nosmep |cmdline| is not set |defconfig | self_protection | OK: not found
294 nosmap |cmdline| is not set |defconfig | self_protection | OK: not found
295 nokaslr |cmdline| is not set |defconfig | self_protection | OK: not found
296 nopti |cmdline| is not set |defconfig | self_protection | OK: not found
297 nospectre_v1 |cmdline| is not set |defconfig | self_protection | OK: not found
298 nospectre_v2 |cmdline| is not set |defconfig | self_protection | OK: not found
299 rodata |cmdline| 1 |defconfig | self_protection | OK: rodata not found
300 init_on_alloc |cmdline| 1 | kspp | self_protection | FAIL: not found
301 init_on_free |cmdline| 1 | kspp | self_protection | FAIL: not found
302 slab_nomerge |cmdline| | kspp | self_protection | OK: CONFIG_SLAB_MERGE_DEFAULT "is not set"
303 iommu.strict |cmdline| 1 | kspp | self_protection | FAIL: not found
304 iommu.passthrough |cmdline| 0 | kspp | self_protection | OK: CONFIG_IOMMU_DEFAULT_PASSTHROUGH "is not set"
305 hardened_usercopy |cmdline| 1 | kspp | self_protection | OK: CONFIG_HARDENED_USERCOPY "y"
306 slab_common.usercopy_fallback |cmdline| 0 | kspp | self_protection | OK: CONFIG_HARDENED_USERCOPY_FALLBACK not found
307 randomize_kstack_offset |cmdline| 1 | kspp | self_protection | OK: CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT "y"
308 pti |cmdline| on | kspp | self_protection | FAIL: not found
309 page_alloc.shuffle |cmdline| 1 | clipos | self_protection | FAIL: not found
310 spectre_v2 |cmdline| on | clipos | self_protection | FAIL: not found
311 vsyscall |cmdline| none | kspp |cut_attack_surface| FAIL: not found
312 debugfs |cmdline| off | grsec |cut_attack_surface| FAIL: not found
314 [+] Config check is finished: 'OK' - 101 / 'FAIL' - 101
317 ## kconfig-hardened-check versioning
319 I usually update the kernel security hardening recommendations every few kernel releases.
321 So the version of `kconfig-hardened-check` is associated with the corresponding version of the kernel.
323 The version format is: __[major_number].[kernel_version].[kernel_patchlevel]__
326 ## Questions and answers
328 __Q:__ How all these kernel parameters influence the Linux kernel security?
330 __A:__ To answer this question, you can use the `kconfig-hardened-check` [sources of recommendations][24]
331 and the [Linux Kernel Defence Map][4] with its references.
335 __Q:__ How disabling `CONFIG_USER_NS` cuts the attack surface? It's needed for containers!
337 __A:__ Yes, the `CONFIG_USER_NS` option provides some isolation between the userspace programs,
338 but the tool recommends disabling it to cut the attack surface __of the kernel__.
342 - An LWN article about the corresponding LKML discussion: https://lwn.net/Articles/673597/
344 - A twitter thread about `CONFIG_USER_NS` and security: https://twitter.com/robertswiecki/status/1095447678949953541
346 - A good overview of the trade-off between having user namespaces enabled, disabled and available only for root: https://github.com/NixOS/nixpkgs/pull/84522#issuecomment-614640601
350 __Q:__ KSPP and CLIP OS recommend `CONFIG_PANIC_ON_OOPS=y`. Why doesn't this tool do the same?
352 __A:__ I personally don't support this recommendation because:
353 - It decreases system safety (kernel oops is still not a rare situation)
354 - It allows easier denial-of-service attacks for the whole system
356 I think having `CONFIG_BUG` is enough here.
357 If a kernel oops happens in the process context, the offending/attacking process is killed.
358 In other cases, the kernel panics, which is similar to `CONFIG_PANIC_ON_OOPS=y`.
362 __Q:__ Why enabling `CONFIG_STATIC_USERMODEHELPER` breaks various things in my GNU/Linux system?
363 Do I really need that feature?
365 __A:__ Linux kernel usermode helpers can be used for privilege escalation in kernel exploits
366 ([example 1][9], [example 2][10]). `CONFIG_STATIC_USERMODEHELPER` prevents that method. But it
367 requires the corresponding support in the userspace: see the [example implementation][11] by
368 Tycho Andersen [@tych0][12].
372 __Q:__ What about performance impact of these security hardening options?
374 __A:__ Ike Devolder [@BlackIkeEagle][7] made some performance tests and described the results in [this article][8].
375 A more detailed evaluation is in the TODO list (the issue [#66][21]).
379 __Q:__ Can I easily check which kernel versions support some Kconfig option?
381 __A:__ Yes. See the [LKDDb][18] project (Linux Kernel Driver Database) by Giacomo Catenazzi [@cateee][19].
382 You can use it for the `mainline` or `stable` tree from [kernel.org][20] or for your custom kernel sources.
386 __Q:__ Does my kernel have all those mitigations of Transient Execution Vulnerabilities in my hardware?
388 __A:__ Checking the kernel config is not enough to answer this question.
389 I highly recommend using [spectre-meltdown-checker][13] tool maintained by Stéphane Lesimple [@speed47][14].
393 __Q:__ Why the `CONFIG_GCC_PLUGINS` option is automatically disabled during the kernel compilation?
395 __A:__ It means that your gcc doesn't support plugins. For example, if you have `gcc-7` on Ubuntu,
396 try to install `gcc-7-plugin-dev` package, it should help.
399 [1]: http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
400 [2]: https://docs.clip-os.org/clipos/kernel.html#configuration
401 [3]: https://grsecurity.net/
402 [4]: https://github.com/a13xp0p0v/linux-kernel-defence-map
403 [5]: https://lwn.net/Articles/791863/
404 [6]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/38
405 [7]: https://github.com/BlackIkeEagle
406 [8]: https://blog.herecura.eu/blog/2020-05-30-kconfig-hardening-tests/
407 [9]: https://googleprojectzero.blogspot.com/2018/09/a-cache-invalidation-bug-in-linux.html
408 [10]: https://a13xp0p0v.github.io/2020/02/15/CVE-2019-18683.html
409 [11]: https://github.com/tych0/huldufolk
410 [12]: https://github.com/tych0
411 [13]: https://github.com/speed47/spectre-meltdown-checker
412 [14]: https://github.com/speed47
413 [15]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/53
414 [16]: https://github.com/a13xp0p0v/kconfig-hardened-check/pull/54
415 [17]: https://github.com/a13xp0p0v/kconfig-hardened-check/pull/62
416 [18]: https://cateee.net/lkddb/web-lkddb/
417 [19]: https://github.com/cateee/lkddb
418 [20]: https://kernel.org/
419 [21]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/66
420 [22]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/56
421 [23]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues?q=label%3Akernel_maintainer_feedback
422 [24]: https://github.com/a13xp0p0v/kconfig-hardened-check#motivation
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