1 # Kconfig hardened check
5 There are plenty of Linux kernel hardening config options. A lot of them are
6 not enabled by the major distros. We have to enable these options ourselves to
7 make our systems more secure.
9 But nobody likes checking configs manually. So let the computers do their job!
11 __kconfig-hardened-check.py__ helps me to check the Linux kernel Kconfig option list
12 against my hardening preferences, which are based on the
14 - [KSPP recommended settings][1],
15 - [CLIP OS kernel configuration][2],
16 - last public [grsecurity][3] patch (options which they disable).
18 I also created [__Linux Kernel Defence Map__][4] that is a graphical representation of the
19 relationships between these hardening features and the corresponding vulnerability classes
20 or exploitation techniques.
22 ## Supported microarchitectures
29 ## Script output examples
33 usage: kconfig-hardened-check.py [-h] [-p {X86_64,X86_32,ARM64,ARM}]
34 [-c CONFIG] [--debug] [--json]
36 Checks the hardening options in the Linux kernel config
39 -h, --help show this help message and exit
40 -p {X86_64,X86_32,ARM64,ARM}, --print {X86_64,X86_32,ARM64,ARM}
41 print hardening preferences for selected architecture
42 -c CONFIG, --config CONFIG
43 check the config_file against these preferences
44 --debug enable internal debug mode
45 --json print results in JSON format
49 ### Script output for `Ubuntu 18.04 (Bionic Beaver)` kernel config
51 #./kconfig-hardened-check.py -c config_files/distros/ubuntu-bionic-generic.config
52 [+] Trying to detect architecture in "config_files/distros/ubuntu-bionic-generic.config"...
53 [+] Detected architecture: X86_64
54 [+] Checking "config_files/distros/ubuntu-bionic-generic.config" against hardening preferences...
55 option name | desired val | decision | reason || check result
56 =========================================================================================================================
57 CONFIG_BUG | y |defconfig | self_protection || OK
58 CONFIG_STRICT_KERNEL_RWX | y |defconfig | self_protection || OK
59 CONFIG_STACKPROTECTOR_STRONG | y |defconfig | self_protection ||OK: CONFIG_CC_STACKPROTECTOR_STRONG "y"
60 CONFIG_SLUB_DEBUG | y |defconfig | self_protection || OK
61 CONFIG_STRICT_MODULE_RWX | y |defconfig | self_protection || OK
62 CONFIG_MICROCODE | y |defconfig | self_protection || OK
63 CONFIG_RETPOLINE | y |defconfig | self_protection || OK
64 CONFIG_X86_SMAP | y |defconfig | self_protection || OK
65 CONFIG_X86_UMIP | y |defconfig | self_protection ||OK: CONFIG_X86_INTEL_UMIP "y"
66 CONFIG_IOMMU_SUPPORT | y |defconfig | self_protection || OK
67 CONFIG_SYN_COOKIES | y |defconfig | self_protection || OK
68 CONFIG_PAGE_TABLE_ISOLATION | y |defconfig | self_protection || OK
69 CONFIG_RANDOMIZE_MEMORY | y |defconfig | self_protection || OK
70 CONFIG_INTEL_IOMMU | y |defconfig | self_protection || OK
71 CONFIG_AMD_IOMMU | y |defconfig | self_protection || OK
72 CONFIG_VMAP_STACK | y |defconfig | self_protection || OK
73 CONFIG_RANDOMIZE_BASE | y |defconfig | self_protection || OK
74 CONFIG_THREAD_INFO_IN_TASK | y |defconfig | self_protection || OK
75 CONFIG_BUG_ON_DATA_CORRUPTION | y | kspp | self_protection || FAIL: "is not set"
76 CONFIG_DEBUG_WX | y | kspp | self_protection || OK
77 CONFIG_SCHED_STACK_END_CHECK | y | kspp | self_protection || OK
78 CONFIG_SLAB_FREELIST_HARDENED | y | kspp | self_protection || OK
79 CONFIG_SLAB_FREELIST_RANDOM | y | kspp | self_protection || OK
80 CONFIG_SHUFFLE_PAGE_ALLOCATOR | y | kspp | self_protection || FAIL: not found
81 CONFIG_FORTIFY_SOURCE | y | kspp | self_protection || OK
82 CONFIG_GCC_PLUGINS | y | kspp | self_protection || FAIL: "is not set"
83 CONFIG_GCC_PLUGIN_RANDSTRUCT | y | kspp | self_protection || FAIL: not found
84 CONFIG_GCC_PLUGIN_LATENT_ENTROPY | y | kspp | self_protection || FAIL: not found
85 CONFIG_DEBUG_LIST | y | kspp | self_protection || FAIL: "is not set"
86 CONFIG_DEBUG_SG | y | kspp | self_protection || FAIL: "is not set"
87 CONFIG_DEBUG_CREDENTIALS | y | kspp | self_protection || FAIL: "is not set"
88 CONFIG_DEBUG_NOTIFIERS | y | kspp | self_protection || FAIL: "is not set"
89 CONFIG_PAGE_POISONING | y | kspp | self_protection || FAIL: "is not set"
90 CONFIG_HARDENED_USERCOPY | y | kspp | self_protection || OK
91 CONFIG_HARDENED_USERCOPY_FALLBACK | is not set | kspp | self_protection || OK: not found
92 CONFIG_MODULE_SIG | y | kspp | self_protection || OK
93 CONFIG_MODULE_SIG_ALL | y | kspp | self_protection || OK
94 CONFIG_MODULE_SIG_SHA512 | y | kspp | self_protection || OK
95 CONFIG_MODULE_SIG_FORCE | y | kspp | self_protection || FAIL: "is not set"
96 CONFIG_DEFAULT_MMAP_MIN_ADDR | 65536 | kspp | self_protection || OK
97 CONFIG_REFCOUNT_FULL | y | kspp | self_protection || FAIL: "is not set"
98 CONFIG_INIT_STACK_ALL | y | clipos | self_protection || FAIL: not found
99 CONFIG_INIT_ON_ALLOC_DEFAULT_ON | y | clipos | self_protection || FAIL: not found
100 CONFIG_INIT_ON_FREE_DEFAULT_ON | y | clipos | self_protection || FAIL: not found
101 CONFIG_SECURITY_DMESG_RESTRICT | y | clipos | self_protection || FAIL: "is not set"
102 CONFIG_DEBUG_VIRTUAL | y | clipos | self_protection || FAIL: "is not set"
103 CONFIG_STATIC_USERMODEHELPER | y | clipos | self_protection || FAIL: "is not set"
104 CONFIG_SLAB_MERGE_DEFAULT | is not set | clipos | self_protection || FAIL: "y"
105 CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE | is not set | clipos | self_protection ||FAIL: CONFIG_GCC_PLUGIN_RANDSTRUCT is needed
106 CONFIG_GCC_PLUGIN_STACKLEAK | y | clipos | self_protection || FAIL: not found
107 CONFIG_STACKLEAK_METRICS | is not set | clipos | self_protection ||FAIL: CONFIG_GCC_PLUGIN_STACKLEAK is needed
108 CONFIG_STACKLEAK_RUNTIME_DISABLE | is not set | clipos | self_protection ||FAIL: CONFIG_GCC_PLUGIN_STACKLEAK is needed
109 CONFIG_RANDOM_TRUST_CPU | is not set | clipos | self_protection || OK: not found
110 CONFIG_INTEL_IOMMU_SVM | y | clipos | self_protection || OK
111 CONFIG_INTEL_IOMMU_DEFAULT_ON | y | clipos | self_protection || FAIL: "is not set"
112 CONFIG_SLUB_DEBUG_ON | y | my | self_protection || FAIL: "is not set"
113 CONFIG_RESET_ATTACK_MITIGATION | y | my | self_protection || OK
114 CONFIG_PAGE_POISONING_NO_SANITY | is not set | my | self_protection ||FAIL: CONFIG_PAGE_POISONING is needed
115 CONFIG_PAGE_POISONING_ZERO | is not set | my | self_protection ||FAIL: CONFIG_PAGE_POISONING is needed
116 CONFIG_AMD_IOMMU_V2 | y | my | self_protection || FAIL: "m"
117 CONFIG_SECURITY | y |defconfig | security_policy || OK
118 CONFIG_SECURITY_YAMA | y | kspp | security_policy || OK
119 CONFIG_SECURITY_LOADPIN | y | my | security_policy || FAIL: "is not set"
120 CONFIG_SECURITY_LOCKDOWN_LSM | y | my | security_policy || FAIL: not found
121 CONFIG_SECURITY_LOCKDOWN_LSM_EARLY | y | my | security_policy || FAIL: not found
122 CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY| y | my | security_policy || FAIL: not found
123 CONFIG_SECCOMP | y |defconfig | cut_attack_surface || OK
124 CONFIG_SECCOMP_FILTER | y |defconfig | cut_attack_surface || OK
125 CONFIG_STRICT_DEVMEM | y |defconfig | cut_attack_surface || OK
126 CONFIG_MODULES | is not set | kspp | cut_attack_surface || FAIL: "y"
127 CONFIG_DEVMEM | is not set | kspp | cut_attack_surface || FAIL: "y"
128 CONFIG_IO_STRICT_DEVMEM | y | kspp | cut_attack_surface || FAIL: "is not set"
129 CONFIG_ACPI_CUSTOM_METHOD | is not set | kspp | cut_attack_surface || OK
130 CONFIG_COMPAT_BRK | is not set | kspp | cut_attack_surface || OK
131 CONFIG_DEVKMEM | is not set | kspp | cut_attack_surface || OK
132 CONFIG_COMPAT_VDSO | is not set | kspp | cut_attack_surface || OK
133 CONFIG_BINFMT_MISC | is not set | kspp | cut_attack_surface || FAIL: "m"
134 CONFIG_INET_DIAG | is not set | kspp | cut_attack_surface || FAIL: "m"
135 CONFIG_KEXEC | is not set | kspp | cut_attack_surface || FAIL: "y"
136 CONFIG_PROC_KCORE | is not set | kspp | cut_attack_surface || FAIL: "y"
137 CONFIG_LEGACY_PTYS | is not set | kspp | cut_attack_surface || FAIL: "y"
138 CONFIG_HIBERNATION | is not set | kspp | cut_attack_surface || FAIL: "y"
139 CONFIG_LEGACY_VSYSCALL_NONE | y | kspp | cut_attack_surface || FAIL: "is not set"
140 CONFIG_IA32_EMULATION | is not set | kspp | cut_attack_surface || FAIL: "y"
141 CONFIG_X86_X32 | is not set | kspp | cut_attack_surface || FAIL: "y"
142 CONFIG_MODIFY_LDT_SYSCALL | is not set | kspp | cut_attack_surface || FAIL: "y"
143 CONFIG_X86_PTDUMP | is not set |grsecurity| cut_attack_surface || OK
144 CONFIG_ZSMALLOC_STAT | is not set |grsecurity| cut_attack_surface || OK
145 CONFIG_PAGE_OWNER | is not set |grsecurity| cut_attack_surface || OK
146 CONFIG_DEBUG_KMEMLEAK | is not set |grsecurity| cut_attack_surface || OK
147 CONFIG_BINFMT_AOUT | is not set |grsecurity| cut_attack_surface || OK: not found
148 CONFIG_KPROBES | is not set |grsecurity| cut_attack_surface || FAIL: "y"
149 CONFIG_UPROBES | is not set |grsecurity| cut_attack_surface || FAIL: "y"
150 CONFIG_GENERIC_TRACER | is not set |grsecurity| cut_attack_surface || FAIL: "y"
151 CONFIG_PROC_VMCORE | is not set |grsecurity| cut_attack_surface || FAIL: "y"
152 CONFIG_PROC_PAGE_MONITOR | is not set |grsecurity| cut_attack_surface || FAIL: "y"
153 CONFIG_USELIB | is not set |grsecurity| cut_attack_surface || FAIL: "y"
154 CONFIG_CHECKPOINT_RESTORE | is not set |grsecurity| cut_attack_surface || FAIL: "y"
155 CONFIG_USERFAULTFD | is not set |grsecurity| cut_attack_surface || FAIL: "y"
156 CONFIG_HWPOISON_INJECT | is not set |grsecurity| cut_attack_surface || FAIL: "m"
157 CONFIG_MEM_SOFT_DIRTY | is not set |grsecurity| cut_attack_surface || FAIL: "y"
158 CONFIG_DEVPORT | is not set |grsecurity| cut_attack_surface || FAIL: "y"
159 CONFIG_DEBUG_FS | is not set |grsecurity| cut_attack_surface || FAIL: "y"
160 CONFIG_NOTIFIER_ERROR_INJECTION | is not set |grsecurity| cut_attack_surface || FAIL: "m"
161 CONFIG_ACPI_TABLE_UPGRADE | is not set | lockdown | cut_attack_surface || FAIL: "y"
162 CONFIG_ACPI_APEI_EINJ | is not set | lockdown | cut_attack_surface || FAIL: "m"
163 CONFIG_PROFILING | is not set | lockdown | cut_attack_surface || FAIL: "y"
164 CONFIG_BPF_SYSCALL | is not set | lockdown | cut_attack_surface || FAIL: "y"
165 CONFIG_MMIOTRACE_TEST | is not set | lockdown | cut_attack_surface || OK
166 CONFIG_KSM | is not set | clipos | cut_attack_surface || FAIL: "y"
167 CONFIG_KALLSYMS | is not set | clipos | cut_attack_surface || FAIL: "y"
168 CONFIG_X86_VSYSCALL_EMULATION | is not set | clipos | cut_attack_surface || FAIL: "y"
169 CONFIG_MAGIC_SYSRQ | is not set | clipos | cut_attack_surface || FAIL: "y"
170 CONFIG_KEXEC_FILE | is not set | clipos | cut_attack_surface || FAIL: "y"
171 CONFIG_USER_NS | is not set | clipos | cut_attack_surface || FAIL: "y"
172 CONFIG_LDISC_AUTOLOAD | is not set | clipos | cut_attack_surface || OK: not found
173 CONFIG_MMIOTRACE | is not set | my | cut_attack_surface || FAIL: "y"
174 CONFIG_LIVEPATCH | is not set | my | cut_attack_surface || FAIL: "y"
175 CONFIG_IP_DCCP | is not set | my | cut_attack_surface || FAIL: "m"
176 CONFIG_IP_SCTP | is not set | my | cut_attack_surface || FAIL: "m"
177 CONFIG_FTRACE | is not set | my | cut_attack_surface || FAIL: "y"
178 CONFIG_BPF_JIT | is not set | my | cut_attack_surface || FAIL: "y"
179 CONFIG_ARCH_MMAP_RND_BITS | 32 | clipos |userspace_protection|| FAIL: "28"
181 [+] config check is finished: 'OK' - 48 / 'FAIL' - 75
184 ## kconfig-hardened-check versioning
186 I usually update the kernel hardening recommendations after each Linux kernel release.
188 So the version of `kconfig-hardened-check` is associated with the corresponding version of the kernel.
190 The version format is: __[major_number].[kernel_version]__
192 The current version of `kconfig-hardened-check` is __0.5.3__, it's marked with the git tag.
195 ## Questions and answers
197 __Q:__ How disabling `CONFIG_USER_NS` cuts the attack surface? It's needed for containers!
199 __A:__ Yes, the `CONFIG_USER_NS` option provides some isolation between the userspace programs,
200 but the script recommends disabling it to cut the attack surface __of the kernel__.
204 - A nice LWN article about the corresponding LKML discussion: https://lwn.net/Articles/673597/
206 - A twitter thread about `CONFIG_USER_NS` and security: https://twitter.com/robertswiecki/status/1095447678949953541
210 __Q:__ Why `CONFIG_GCC_PLUGINS` is automatically disabled during the kernel compilation?
212 __A:__ It means that your gcc doesn't support plugins. For example, if you have `gcc-7` on Ubuntu,
213 try to install `gcc-7-plugin-dev` package, it should help.
216 [1]: http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
217 [2]: https://docs.clip-os.org/clipos/kernel.html#configuration
218 [3]: https://grsecurity.net/
219 [4]: https://github.com/a13xp0p0v/linux-kernel-defence-map
projects / kconfig-hardened-check.git / blob