a13xp0p0v/kernel-hardening-checker

# kernel-hardening-checker __(formerly kconfig-hardened-check)__ [](https://github.com/a13xp0p0v/kernel-hardening-checker/tags) [](https://www.gnu.org/licenses/gpl-3.0)
[](https://ci.codeberg.org/repos/12605)
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[](https://github.com/a13xp0p0v/kernel-hardening-checker/actions/workflows/static_analysis.yml) [](https://github.com/a13xp0p0v/kernel-hardening-checker/actions/workflows/package_test.yml) ## Motivation There are plenty of security hardening options for the Linux kernel. A lot of them are not enabled by the major distros. We have to enable these options ourselves to make our systems more secure. But nobody likes checking configs manually. So let the computers do their job! __kernel-hardening-checker__ (formerly __kconfig-hardened-check__) is a tool for checking the security hardening options of the Linux kernel. License: GPL-3.0. ## Repositories - At GitHub - At Codeberg: (go there if something goes wrong with GitHub) - At SourceCraft: ## Features `kernel-hardening-checker` supports checking: - Kconfig options (compile-time) - Kernel command line arguments (boot-time) - Sysctl parameters (runtime) Supported architectures: - X86_64 - X86_32 - ARM64 - ARM - RISC-V The security hardening recommendations are based on: - [KSPP recommended settings][1] - [Direct feedback from the Linux kernel maintainers][23] - Kernel options disabled by [grsecurity][3] to cut attack surface - [CLIP OS kernel configuration][2] - [GrapheneOS][25] recommendations - [SECURITY_LOCKDOWN_LSM][5] patchset - [CIS Benchmark][27] I also created the [__Linux Kernel Defence Map__][4], which is a graphical representation of the relationships between security hardening features and the corresponding vulnerability classes or exploitation techniques. ## Attention! Please note that changing the Linux kernel security parameters may also affect system performance and functionality of userspace software. Therefore, when setting these parameters, consider the threat model of your Linux-based information system and thoroughly test its typical workload. ## Installation There are multiple options: - You can install the package from this Git repository using `pip`: python3 -m pip install git+https://github.com/a13xp0p0v/kernel-hardening-checker If you encounter an error due to an externally managed environment, create a virtual environment using `python3 -m venv`. - You can install the `kernel-hardening-checker` package via the package manager on some GNU/Linux distributions. See - Alternatively, you can simply run `./bin/kernel-hardening-checker` from the cloned repository without installation. ## Usage $ ./bin/kernel-hardening-checker -h usage: kernel-hardening-checker [-h] [--version] [-m {verbose,json,show_ok,show_fail}] [-a] [-c CONFIG] [-v KERNEL_VERSION] [-l CMDLINE] [-s SYSCTL] [-p {X86_64,X86_32,ARM64,ARM,RISCV}] [-g {X86_64,X86_32,ARM64,ARM,RISCV}] A tool for checking the security hardening options of the Linux kernel options: -h, --help show this help message and exit --version show program's version number and exit -m, --mode {verbose,json,show_ok,show_fail} select a special output mode instead of the default one -a, --autodetect autodetect and check the security hardening options of the running kernel -c, --config CONFIG check the security hardening options in a Kconfig file (also supports *.gz files) -v, --kernel-version KERNEL_VERSION extract the kernel version from a version file (such as /proc/version) instead of using a Kconfig file -l, --cmdline CMDLINE check the security hardening options in a kernel command line file (such as /proc/cmdline) -s, --sysctl SYSCTL check the security hardening options in a sysctl output file (the result of "sudo sysctl -a > file") -p, --print {X86_64,X86_32,ARM64,ARM,RISCV} print security hardening recommendations for the selected architecture -g, --generate {X86_64,X86_32,ARM64,ARM,RISCV} generate a Kconfig fragment containing the security hardening options for the selected architecture ## Output modes - no `-m` argument for the default output mode (see the example below) - `-m verbose` for printing additional info: - the configuration options without a corresponding check - the internals of complex checks with AND/OR, like this: ------------------------------------------------------------------------------------------- <<< OR >>> CONFIG_STRICT_DEVMEM |kconfig|cut_attack_surface|defconfig | y CONFIG_DEVMEM |kconfig|cut_attack_surface| kspp | is not set ------------------------------------------------------------------------------------------- - `-m json` for printing the results in JSON format (for combining `kernel-hardening-checker` with other tools) - `-m show_ok` for showing only successful checks - `-m show_fail` for showing only failed checks ## Example output $ ./bin/kernel-hardening-checker -a [+] Going to autodetect and check the security hardening options of the running kernel [+] Detected version of the running kernel: (6, 11, 0) [+] Detected kconfig file of the running kernel: /boot/config-6.11.0-1007-oem [+] Detected cmdline parameters of the running kernel: /proc/cmdline [+] Saved sysctls to a temporary file /tmp/sysctl-at_0n9si [+] Detected architecture: X86_64 [+] Detected compiler: GCC 130200 [!] WARNING: sysctl options available for root are not found in /tmp/sysctl-at_0n9si, try checking the output of "sudo sysctl -a" ========================================================================================================================= option_name | type | reason | decision |desired_val | check_result ========================================================================================================================= CONFIG_BUG |kconfig| self_protection |defconfig | y | OK CONFIG_SLUB_DEBUG |kconfig| self_protection |defconfig | y | OK CONFIG_THREAD_INFO_IN_TASK |kconfig| self_protection |defconfig | y | OK CONFIG_IOMMU_DEFAULT_PASSTHROUGH |kconfig| self_protection |defconfig | is not set | OK CONFIG_IOMMU_SUPPORT |kconfig| self_protection |defconfig | y | OK CONFIG_STACKPROTECTOR |kconfig| self_protection |defconfig | y | OK CONFIG_STACKPROTECTOR_STRONG |kconfig| self_protection |defconfig | y | OK CONFIG_STRICT_KERNEL_RWX |kconfig| self_protection |defconfig | y | OK CONFIG_STRICT_MODULE_RWX |kconfig| self_protection |defconfig | y | OK CONFIG_REFCOUNT_FULL |kconfig| self_protection |defconfig | y | OK: version >= (5, 4, 208) CONFIG_INIT_STACK_ALL_ZERO |kconfig| self_protection |defconfig | y | OK CONFIG_CPU_MITIGATIONS |kconfig| self_protection |defconfig | y | OK CONFIG_RANDOMIZE_BASE |kconfig| self_protection |defconfig | y | OK CONFIG_VMAP_STACK |kconfig| self_protection |defconfig | y | OK CONFIG_LSM_MMAP_MIN_ADDR |kconfig| self_protection |defconfig | 65536 | FAIL: "0" CONFIG_DEBUG_WX |kconfig| self_protection |defconfig | y | OK CONFIG_WERROR |kconfig| self_protection |defconfig | y | FAIL: "is not set" CONFIG_X86_MCE |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_SPECTRE_V1 |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_SPECTRE_V2 |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_SSB |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MICROCODE |kconfig| self_protection |defconfig | y | OK CONFIG_MICROCODE_INTEL |kconfig| self_protection |defconfig | y | OK: CONFIG_MICROCODE is "y" CONFIG_MICROCODE_AMD |kconfig| self_protection |defconfig | y | OK: CONFIG_MICROCODE is "y" CONFIG_X86_SMAP |kconfig| self_protection |defconfig | y | OK: version >= (5, 19, 0) CONFIG_X86_UMIP |kconfig| self_protection |defconfig | y | OK CONFIG_X86_MCE_INTEL |kconfig| self_protection |defconfig | y | OK CONFIG_X86_MCE_AMD |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_RETPOLINE |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_GDS |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_RFDS |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_SPECTRE_BHI |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_MDS |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_TAA |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_MMIO_STALE_DATA |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_L1TF |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_RETBLEED |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_SRBDS |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_TSA |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_MITIGATION_VMSCAPE |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_RANDOMIZE_MEMORY |kconfig| self_protection |defconfig | y | OK CONFIG_X86_KERNEL_IBT |kconfig| self_protection |defconfig | y | FAIL: "is not set" CONFIG_MITIGATION_RETHUNK |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_PAGE_TABLE_ISOLATION|kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_UNRET_ENTRY |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_CALL_DEPTH_TRACKING |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_IBPB_ENTRY |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_IBRS_ENTRY |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_SRSO |kconfig| self_protection |defconfig | y | OK CONFIG_MITIGATION_ITS |kconfig| self_protection |defconfig | y | FAIL: is not found CONFIG_INTEL_IOMMU |kconfig| self_protection |defconfig | y | OK CONFIG_AMD_IOMMU |kconfig| self_protection |defconfig | y | OK CONFIG_RANDOM_KMALLOC_CACHES |kconfig| self_protection | kspp | y | OK CONFIG_SLAB_MERGE_DEFAULT |kconfig| self_protection | kspp | is not set | FAIL: "y" CONFIG_BUG_ON_DATA_CORRUPTION |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_SLAB_FREELIST_HARDENED |kconfig| self_protection | kspp | y | OK CONFIG_SLAB_FREELIST_RANDOM |kconfig| self_protection | kspp | y | OK CONFIG_SHUFFLE_PAGE_ALLOCATOR |kconfig| self_protection | kspp | y | OK CONFIG_FORTIFY_SOURCE |kconfig| self_protection | kspp | y | OK CONFIG_DEBUG_VIRTUAL |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_INIT_ON_ALLOC_DEFAULT_ON |kconfig| self_protection | kspp | y | OK CONFIG_STATIC_USERMODEHELPER |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_SECURITY_LOCKDOWN_LSM |kconfig| self_protection | kspp | y | OK CONFIG_LSM |kconfig| self_protection | kspp | *lockdown* | OK: in "landlock,lockdown,yama,integrity,apparmor" CONFIG_SECURITY_LOCKDOWN_LSM_EARLY |kconfig| self_protection | kspp | y | OK CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY|kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_DEBUG_SG |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_ZERO_CALL_USED_REGS |kconfig| self_protection | kspp | y | OK CONFIG_DEBUG_CREDENTIALS |kconfig| self_protection | kspp | y | OK: version >= (6, 6, 8) CONFIG_DEBUG_NOTIFIERS |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_KFENCE |kconfig| self_protection | kspp | y | OK CONFIG_KFENCE_SAMPLE_INTERVAL |kconfig| self_protection | kspp | 100 | FAIL: "0" CONFIG_RANDSTRUCT_FULL |kconfig| self_protection | kspp | y | FAIL: is not found CONFIG_HARDENED_USERCOPY |kconfig| self_protection | kspp | y | OK CONFIG_HARDENED_USERCOPY_DEFAULT_ON |kconfig| self_protection | kspp | y | FAIL: is not found CONFIG_HARDENED_USERCOPY_FALLBACK |kconfig| self_protection | kspp | is not set | OK: is not found CONFIG_HARDENED_USERCOPY_PAGESPAN |kconfig| self_protection | kspp | is not set | OK: is not found CONFIG_GCC_PLUGIN_LATENT_ENTROPY |kconfig| self_protection | kspp | y | FAIL: is not found CONFIG_MODULE_SIG |kconfig| self_protection | kspp | y | OK CONFIG_MODULE_SIG_ALL |kconfig| self_protection | kspp | y | OK CONFIG_MODULE_SIG_SHA512 |kconfig| self_protection | kspp | y | OK CONFIG_MODULE_SIG_FORCE |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_INIT_ON_FREE_DEFAULT_ON |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_EFI_DISABLE_PCI_DMA |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_RESET_ATTACK_MITIGATION |kconfig| self_protection | kspp | y | OK CONFIG_UBSAN_BOUNDS |kconfig| self_protection | kspp | y | OK CONFIG_UBSAN_LOCAL_BOUNDS |kconfig| self_protection | kspp | y | OK: CONFIG_UBSAN_BOUNDS is "y" CONFIG_UBSAN_TRAP |kconfig| self_protection | kspp | y | FAIL: CONFIG_UBSAN_ENUM is not "is not set" CONFIG_UBSAN_SANITIZE_ALL |kconfig| self_protection | kspp | y | OK: CONFIG_UBSAN_BOUNDS is "y" CONFIG_SCHED_STACK_END_CHECK |kconfig| self_protection | kspp | y | OK CONFIG_KSTACK_ERASE |kconfig| self_protection | kspp | y | FAIL: is not found CONFIG_KSTACK_ERASE_METRICS |kconfig| self_protection | kspp | is not set | FAIL: CONFIG_KSTACK_ERASE is not "y" CONFIG_KSTACK_ERASE_RUNTIME_DISABLE |kconfig| self_protection | kspp | is not set | FAIL: CONFIG_KSTACK_ERASE is not "y" CONFIG_SCHED_CORE |kconfig| self_protection | kspp | y | OK CONFIG_LIST_HARDENED |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT|kconfig| self_protection | kspp | y | OK CONFIG_PAGE_TABLE_CHECK |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_PAGE_TABLE_CHECK_ENFORCED |kconfig| self_protection | kspp | y | FAIL: is not found CONFIG_DEFAULT_MMAP_MIN_ADDR |kconfig| self_protection | kspp | 65536 | OK CONFIG_HW_RANDOM_TPM |kconfig| self_protection | kspp | y | OK CONFIG_CFI_CLANG |kconfig| self_protection | kspp | y | FAIL: CONFIG_CC_IS_CLANG is not "y" CONFIG_CFI_PERMISSIVE |kconfig| self_protection | kspp | is not set | FAIL: CONFIG_CC_IS_CLANG is not "y" CONFIG_IOMMU_DEFAULT_DMA_STRICT |kconfig| self_protection | kspp | y | FAIL: "is not set" CONFIG_INTEL_IOMMU_DEFAULT_ON |kconfig| self_protection | kspp | y | OK CONFIG_CFI_AUTO_DEFAULT |kconfig| self_protection | kspp | is not set | FAIL: CONFIG_CFI_AUTO_DEFAULT is not present CONFIG_MITIGATION_SLS |kconfig| self_protection | kspp | y | OK CONFIG_INTEL_IOMMU_SVM |kconfig| self_protection | kspp | y | OK CONFIG_AMD_IOMMU_V2 |kconfig| self_protection | kspp | y | OK: version >= (6, 7, 0) CONFIG_SECURITY |kconfig| security_policy |defconfig | y | OK CONFIG_SECURITY_YAMA |kconfig| security_policy | kspp | y | OK CONFIG_LSM |kconfig| security_policy | kspp | *yama* | OK: in "landlock,lockdown,yama,integrity,apparmor" CONFIG_SECURITY_LANDLOCK |kconfig| security_policy | kspp | y | OK CONFIG_LSM |kconfig| security_policy | kspp | *landlock* | OK: in "landlock,lockdown,yama,integrity,apparmor" CONFIG_SECURITY_SELINUX_DISABLE |kconfig| security_policy | kspp | is not set | OK: is not found CONFIG_SECURITY_SELINUX_BOOTPARAM |kconfig| security_policy | kspp | is not set | FAIL: "y" CONFIG_SECURITY_SELINUX_DEVELOP |kconfig| security_policy | kspp | is not set | FAIL: "y" CONFIG_SECURITY_WRITABLE_HOOKS |kconfig| security_policy | kspp | is not set | OK: is not found CONFIG_SECURITY_SELINUX_DEBUG |kconfig| security_policy | kspp | is not set | OK CONFIG_SECURITY_SELINUX |kconfig| security_policy |a13xp0p0v | y | OK CONFIG_LSM |kconfig| security_policy |a13xp0p0v | *selinux* | OK: "apparmor" is in CONFIG_LSM CONFIG_SECCOMP |kconfig|cut_attack_surface|defconfig | y | OK CONFIG_SECCOMP_FILTER |kconfig|cut_attack_surface|defconfig | y | OK CONFIG_BPF_UNPRIV_DEFAULT_OFF |kconfig|cut_attack_surface|defconfig | y | OK CONFIG_STRICT_DEVMEM |kconfig|cut_attack_surface|defconfig | y | OK CONFIG_X86_INTEL_TSX_MODE_OFF |kconfig|cut_attack_surface|defconfig | y | OK CONFIG_SECURITY_DMESG_RESTRICT |kconfig|cut_attack_surface| kspp | y | OK CONFIG_ACPI_CUSTOM_METHOD |kconfig|cut_attack_surface| kspp | is not set | OK: is not found CONFIG_COMPAT_BRK |kconfig|cut_attack_surface| kspp | is not set | OK CONFIG_DEVKMEM |kconfig|cut_attack_surface| kspp | is not set | OK: is not found CONFIG_BINFMT_MISC |kconfig|cut_attack_surface| kspp | is not set | FAIL: "m" CONFIG_INET_DIAG |kconfig|cut_attack_surface| kspp | is not set | FAIL: "m" CONFIG_KEXEC |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_PROC_KCORE |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_LEGACY_PTYS |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_HIBERNATION |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_COMPAT |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_IA32_EMULATION |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_X86_X32 |kconfig|cut_attack_surface| kspp | is not set | OK: is not found CONFIG_X86_X32_ABI |kconfig|cut_attack_surface| kspp | is not set | OK CONFIG_MODIFY_LDT_SYSCALL |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_OABI_COMPAT |kconfig|cut_attack_surface| kspp | is not set | OK: is not found CONFIG_X86_MSR |kconfig|cut_attack_surface| kspp | is not set | FAIL: "m" CONFIG_LEGACY_TIOCSTI |kconfig|cut_attack_surface| kspp | is not set | OK CONFIG_MODULE_FORCE_LOAD |kconfig|cut_attack_surface| kspp | is not set | OK CONFIG_M486 |kconfig|cut_attack_surface| kspp | is not set | OK: is not found CONFIG_MODULES |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_DEVMEM |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_IO_STRICT_DEVMEM |kconfig|cut_attack_surface| kspp | y | FAIL: "is not set" CONFIG_LDISC_AUTOLOAD |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_X86_VSYSCALL_EMULATION |kconfig|cut_attack_surface| kspp | is not set | FAIL: "y" CONFIG_COMPAT_VDSO |kconfig|cut_attack_surface| kspp | is not set | OK CONFIG_DRM_LEGACY |kconfig|cut_attack_surface|maintainer| is not set | OK: is not found CONFIG_FB |kconfig|cut_attack_surface|maintainer| is not set | FAIL: "y" CONFIG_VT |kconfig|cut_attack_surface|maintainer| is not set | FAIL: "y" CONFIG_BLK_DEV_FD |kconfig|cut_attack_surface|maintainer| is not set | FAIL: "m" CONFIG_BLK_DEV_FD_RAWCMD |kconfig|cut_attack_surface|maintainer| is not set | OK CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT |kconfig|cut_attack_surface|maintainer| is not set | OK: is not found CONFIG_N_GSM |kconfig|cut_attack_surface|maintainer| is not set | FAIL: "m" CONFIG_ZSMALLOC_STAT |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_DEBUG_KMEMLEAK |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_BINFMT_AOUT |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_KPROBE_EVENTS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_UPROBE_EVENTS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_GENERIC_TRACER |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_FUNCTION_TRACER |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_STACK_TRACER |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_HIST_TRIGGERS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_BLK_DEV_IO_TRACE |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_PROC_VMCORE |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_PROC_PAGE_MONITOR |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_USELIB |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_CHECKPOINT_RESTORE |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_USERFAULTFD |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_HWPOISON_INJECT |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_MEM_SOFT_DIRTY |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_DEVPORT |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_DEBUG_FS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_NOTIFIER_ERROR_INJECTION |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_FAIL_FUTEX |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_PUNIT_ATOM_DEBUG |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_ACPI_CONFIGFS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_EDAC_DEBUG |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_DRM_I915_DEBUG |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_DVB_C8SECTPFE |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_MTD_SLRAM |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_MTD_PHRAM |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_IO_URING |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_KCMP |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_RSEQ |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_LATENCYTOP |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_KCOV |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_PROVIDE_OHCI1394_DMA_INIT |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_SUNRPC_DEBUG |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_X86_16BIT |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_BLK_DEV_UBLK |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_SMB_SERVER |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_XFS_ONLINE_SCRUB_STATS |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_CACHESTAT_SYSCALL |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_PREEMPTIRQ_TRACEPOINTS |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_ENABLE_DEFAULT_TRACERS |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_PROVE_LOCKING |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_TEST_DEBUG_VIRTUAL |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_MPTCP |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_TLS |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_TIPC |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_IP_SCTP |kconfig|cut_attack_surface| grsec | is not set | FAIL: "m" CONFIG_KGDB |kconfig|cut_attack_surface| grsec | is not set | FAIL: "y" CONFIG_PTDUMP_DEBUGFS |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_X86_PTDUMP |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_DEBUG_CLOSURES |kconfig|cut_attack_surface| grsec | is not set | OK CONFIG_BCACHE_CLOSURES_DEBUG |kconfig|cut_attack_surface| grsec | is not set | OK: is not found CONFIG_STAGING |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_KSM |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_KALLSYMS |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_KEXEC_FILE |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_CRASH_DUMP |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_USER_NS |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_X86_CPUID |kconfig|cut_attack_surface| clipos | is not set | FAIL: "m" CONFIG_X86_IOPL_IOPERM |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_ACPI_TABLE_UPGRADE |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_EFI_CUSTOM_SSDT_OVERLAYS |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_AIO |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_MAGIC_SYSRQ |kconfig|cut_attack_surface| clipos | is not set | FAIL: "y" CONFIG_MAGIC_SYSRQ_SERIAL |kconfig|cut_attack_surface|grapheneos| is not set | FAIL: "y" CONFIG_EFI_TEST |kconfig|cut_attack_surface| lockdown | is not set | FAIL: "m" CONFIG_MMIOTRACE_TEST |kconfig|cut_attack_surface| lockdown | is not set | OK CONFIG_KPROBES |kconfig|cut_attack_surface| lockdown | is not set | FAIL: "y" CONFIG_BPF_SYSCALL |kconfig|cut_attack_surface| lockdown | is not set | FAIL: "y" CONFIG_MMIOTRACE |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "y" CONFIG_LIVEPATCH |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "y" CONFIG_IP_DCCP |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "m" CONFIG_FTRACE |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "y" CONFIG_VIDEO_VIVID |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "m" CONFIG_INPUT_EVBUG |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "m" CONFIG_CORESIGHT |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK: is not found CONFIG_XFS_SUPPORT_V4 |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "y" CONFIG_BLK_DEV_WRITE_MOUNTED |kconfig|cut_attack_surface|a13xp0p0v | is not set | FAIL: "y" CONFIG_FAULT_INJECTION |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK CONFIG_ARM_PTDUMP_DEBUGFS |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK: is not found CONFIG_ARM_PTDUMP |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK: is not found CONFIG_SECCOMP_CACHE_DEBUG |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK CONFIG_CRASH_DM_CRYPT |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK: is not found CONFIG_LKDTM |kconfig|cut_attack_surface|a13xp0p0v | is not set | OK CONFIG_TRIM_UNUSED_KSYMS |kconfig|cut_attack_surface|a13xp0p0v | y | FAIL: "is not set" CONFIG_SYN_COOKIES |kconfig| network_security |defconfig | y | OK CONFIG_COREDUMP |kconfig| harden_userspace | clipos | is not set | FAIL: "y" CONFIG_PROC_MEM_NO_FORCE |kconfig| harden_userspace |a13xp0p0v | y | FAIL: is not found CONFIG_ARCH_MMAP_RND_BITS |kconfig| harden_userspace |a13xp0p0v | 32 | OK CONFIG_ARCH_MMAP_RND_COMPAT_BITS |kconfig| harden_userspace |a13xp0p0v | 16 | OK CONFIG_X86_USER_SHADOW_STACK |kconfig| harden_userspace | kspp | y | OK nokaslr |cmdline| self_protection |defconfig | is not set | OK: is not found no_hash_pointers |cmdline| self_protection |defconfig | is not set | OK: is not found nosmep |cmdline| self_protection |defconfig | is not set | OK: is not found nosmap |cmdline| self_protection |defconfig | is not set | OK: is not found dis_ucode_ldr |cmdline| self_protection |defconfig | is not set | OK: is not found setcpuid |cmdline| self_protection |defconfig | is not set | OK: is not found clearcpuid |cmdline| self_protection |defconfig | is not set | OK: is not found nopti |cmdline| self_protection |defconfig | is not set | OK: is not found nospec_store_bypass_disable |cmdline| self_protection |defconfig | is not set | OK: is not found nospectre_v1 |cmdline| self_protection |defconfig | is not set | OK: is not found nospectre_v2 |cmdline| self_protection |defconfig | is not set | OK: is not found nospectre_bhb |cmdline| self_protection |defconfig | is not set | OK: is not found arm64.nobti |cmdline| self_protection |defconfig | is not set | OK: is not found arm64.nopauth |cmdline| self_protection |defconfig | is not set | OK: is not found arm64.nomte |cmdline| self_protection |defconfig | is not set | OK: is not found arm64.nogcs |cmdline| self_protection |defconfig | is not set | OK: is not found iommu.passthrough |cmdline| self_protection |defconfig | 0 | OK: CONFIG_IOMMU_DEFAULT_PASSTHROUGH is "is not set" rodata |cmdline| self_protection |defconfig | on | OK: rodata is not found spectre_v2 |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found spectre_v2_user |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found spectre_bhi |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found spec_store_bypass_disable |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found l1tf |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found mds |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found tsx_async_abort |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found srbds |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found mmio_stale_data |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found retbleed |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found spec_rstack_overflow |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found gather_data_sampling |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found reg_file_data_sampling |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found tsa |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found indirect_target_selection |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found vmscape |cmdline| self_protection |defconfig | is not off | FAIL: is off, not found slab_merge |cmdline| self_protection | kspp | is not set | OK: is not found slub_merge |cmdline| self_protection | kspp | is not set | OK: is not found page_alloc.shuffle |cmdline| self_protection | kspp | 1 | FAIL: is not found hash_pointers |cmdline| self_protection | kspp | always | FAIL: is not found slab_nomerge |cmdline| self_protection | kspp | is present | FAIL: is not present init_on_alloc |cmdline| self_protection | kspp | 1 | OK: CONFIG_INIT_ON_ALLOC_DEFAULT_ON is "y" init_on_free |cmdline| self_protection | kspp | 1 | FAIL: is not found hardened_usercopy |cmdline| self_protection | kspp | 1 | FAIL: is not found slab_common.usercopy_fallback |cmdline| self_protection | kspp | is not set | OK: is not found kfence.sample_interval |cmdline| self_protection | kspp | 100 | FAIL: is not found lockdown |cmdline| self_protection | kspp |confidentiality| FAIL: is not found module.sig_enforce |cmdline| self_protection | kspp | 1 | FAIL: is not found efi |cmdline| self_protection | kspp |*disable_early_pci_dma*| FAIL: is not found randomize_kstack_offset |cmdline| self_protection | kspp | 1 | OK: CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT is "y" mitigations |cmdline| self_protection | kspp | auto,nosmt | FAIL: is not found intel_iommu |cmdline| self_protection | kspp | on | OK: CONFIG_INTEL_IOMMU_DEFAULT_ON is "y" iommu.strict |cmdline| self_protection | kspp | 1 | FAIL: is not found pti |cmdline| self_protection | kspp | on | FAIL: is not found cfi |cmdline| self_protection | kspp | kcfi | FAIL: is not found iommu |cmdline| self_protection | clipos | force | FAIL: is not found tsx |cmdline|cut_attack_surface|defconfig | off | OK: CONFIG_X86_INTEL_TSX_MODE_OFF is "y" nosmt |cmdline|cut_attack_surface| kspp | is present | FAIL: is not present vsyscall |cmdline|cut_attack_surface| kspp | none | FAIL: is not found vdso32 |cmdline|cut_attack_surface| kspp | 0 | OK: CONFIG_COMPAT_VDSO is "is not set" ia32_emulation |cmdline|cut_attack_surface| kspp | 0 | FAIL: is not found debugfs |cmdline|cut_attack_surface| grsec | off | FAIL: is not found sysrq_always_enabled |cmdline|cut_attack_surface|grapheneos| is not set | OK: is not found bdev_allow_write_mounted |cmdline|cut_attack_surface|a13xp0p0v | 0 | FAIL: is not found norandmaps |cmdline| harden_userspace |defconfig | is not set | OK: is not found proc_mem.force_override |cmdline| harden_userspace |a13xp0p0v | never | FAIL: is not found net.core.bpf_jit_harden |sysctl | self_protection | kspp | 2 | FAIL: is not found vm.mmap_min_addr |sysctl | self_protection | kspp | 65536 | OK kernel.oops_limit |sysctl | self_protection |a13xp0p0v | 100 | FAIL: "10000" kernel.warn_limit |sysctl | self_protection |a13xp0p0v | 100 | FAIL: "0" kernel.dmesg_restrict |sysctl |cut_attack_surface| kspp | 1 | OK kernel.perf_event_paranoid |sysctl |cut_attack_surface| kspp | 3 | FAIL: "4" dev.tty.ldisc_autoload |sysctl |cut_attack_surface| kspp | 0 | FAIL: "1" kernel.kptr_restrict |sysctl |cut_attack_surface| kspp | 2 | FAIL: "1" dev.tty.legacy_tiocsti |sysctl |cut_attack_surface| kspp | 0 | OK user.max_user_namespaces |sysctl |cut_attack_surface| kspp | 0 | FAIL: "63417" kernel.kexec_load_disabled |sysctl |cut_attack_surface| kspp | 1 | FAIL: "0" kernel.unprivileged_bpf_disabled |sysctl |cut_attack_surface| kspp | 1 | FAIL: "2" vm.unprivileged_userfaultfd |sysctl |cut_attack_surface| kspp | 0 | OK kernel.modules_disabled |sysctl |cut_attack_surface| kspp | 1 | FAIL: "0" kernel.io_uring_disabled |sysctl |cut_attack_surface| grsec | 2 | FAIL: "0" kernel.sysrq |sysctl |cut_attack_surface|a13xp0p0v | 0 | FAIL: "176" net.ipv4.icmp_ignore_bogus_error_responses|sysctl | network_security | cis | 1 | OK net.ipv4.icmp_echo_ignore_broadcasts |sysctl | network_security | cis | 1 | OK net.ipv4.conf.all.accept_redirects |sysctl | network_security | cis | 0 | FAIL: "1" net.ipv4.conf.default.accept_redirects|sysctl | network_security | cis | 0 | FAIL: "1" net.ipv6.conf.all.accept_redirects |sysctl | network_security | cis | 0 | FAIL: "1" net.ipv6.conf.default.accept_redirects|sysctl | network_security | cis | 0 | FAIL: "1" net.ipv4.conf.all.accept_source_route |sysctl | network_security | cis | 0 | OK net.ipv4.conf.default.accept_source_route|sysctl | network_security | cis | 0 | FAIL: "1" net.ipv6.conf.all.accept_source_route |sysctl | network_security | cis | 0 | OK net.ipv6.conf.default.accept_source_route|sysctl | network_security | cis | 0 | OK net.ipv4.tcp_syncookies |sysctl | network_security | cis | 1 | OK net.ipv6.conf.all.accept_ra |sysctl | network_security | cis | 0 | FAIL: "1" net.ipv6.conf.default.accept_ra |sysctl | network_security | cis | 0 | FAIL: "1" fs.protected_symlinks |sysctl | harden_userspace | kspp | 1 | OK fs.protected_hardlinks |sysctl | harden_userspace | kspp | 1 | OK fs.protected_fifos |sysctl | harden_userspace | kspp | 2 | FAIL: "1" fs.protected_regular |sysctl | harden_userspace | kspp | 2 | OK fs.suid_dumpable |sysctl | harden_userspace | kspp | 0 | FAIL: "2" kernel.randomize_va_space |sysctl | harden_userspace | kspp | 2 | OK kernel.yama.ptrace_scope |sysctl | harden_userspace | kspp | 3 | FAIL: "1" vm.mmap_rnd_bits |sysctl | harden_userspace |a13xp0p0v | 32 | FAIL: is not found vm.mmap_rnd_compat_bits |sysctl | harden_userspace |a13xp0p0v | 16 | FAIL: is not found [+] Config check is finished: 'OK' - 168 / 'FAIL' - 184 ## Generating a Kconfig fragment with the security hardening options With the `-g` argument, the tool generates a Kconfig fragment with the security hardening options for the selected architecture. This Kconfig fragment can be merged with the existing Linux kernel config: $ ./bin/kernel-hardening-checker -g X86_64 > /tmp/fragment $ cd ~/linux-src/ $ ./scripts/kconfig/merge_config.sh .config /tmp/fragment Using .config as base Merging /tmp/fragment Value of CONFIG_BUG_ON_DATA_CORRUPTION is redefined by fragment /tmp/fragment: Previous value: # CONFIG_BUG_ON_DATA_CORRUPTION is not set New value: CONFIG_BUG_ON_DATA_CORRUPTION=y ... ## Questions and answers __Q:__ How all these kernel parameters influence the Linux kernel security? __A:__ To answer this question, you can use the `kernel-hardening-checker` [sources of recommendations][24] and the [Linux Kernel Defence Map][4] with its references.
__Q:__ How disabling `CONFIG_USER_NS` cuts the attack surface? It's needed for containers! __A:__ Yes, the `CONFIG_USER_NS` option provides some isolation between the userspace programs, but the tool recommends disabling it to cut the attack surface __of the kernel__. The rationale: - An LWN article about the corresponding LKML discussion: https://lwn.net/Articles/673597/ - A twitter thread about `CONFIG_USER_NS` and security: https://twitter.com/robertswiecki/status/1095447678949953541 - 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
__Q:__ KSPP and CLIP OS recommend `CONFIG_PANIC_ON_OOPS=y`. Why doesn't this tool do the same? __A:__ I can't support this recommendation because: - It decreases system robustness (kernel oops is still not a rare situation even on production systems) - It allows easier denial-of-service attacks for the whole system You should enable `CONFIG_PANIC_ON_OOPS` if: - Your kernel doesn't encounter oopses during a typical workload - Occasional system reboot is not a problem in your use case I see a good compromise, which `kernel-hardening-checker` recommends: - Enable the `CONFIG_BUG` kconfig option. If a kernel oops happens in the process context, the offending/attacking process is killed. In other cases, the kernel panics, which is similar to `CONFIG_PANIC_ON_OOPS=y`. - Set the sysctl options `kernel.oops_limit` and `kernel.warn_limit` to `100`, for example. On the one hand, this value doesn't allow easy DoS. On the other hand, it is not too large to miss the vulnerability exploitation attempts generating a lot of kernel warnings or oopses.
__Q:__ Why enabling `CONFIG_STATIC_USERMODEHELPER` breaks various things in my GNU/Linux system? Do I really need that feature? __A:__ Linux kernel usermode helpers can be used for privilege escalation in kernel exploits ([example 1][9], [example 2][10]). `CONFIG_STATIC_USERMODEHELPER` prevents that method. But it requires the corresponding support in the userspace: see the [example implementation][11] by Tycho Andersen [@tych0][12].
__Q:__ What about performance impact of these security hardening features? __A:__ That is not an easy question, since performance impact depends on the system workload. A detailed evaluation of the performance impact of Linux security hardening features is in TODO (the issue [#66][21]). There are some interesting works in this area: - Ike Devolder [@BlackIkeEagle][7] made some performance tests and described the results in [this article][8]. - Fabian Rauscher, Benedict Herzog, Timo Hönig, and Daniel Gruss published an article ["Systematic Analysis of Kernel Security Performance and Energy Costs"][28] that describes energy and run-time overhead of the hardware vulnerability mitigations (CONFIG_CPU_MITIGATIONS).
__Q:__ Does my kernel have all those mitigations of Transient Execution Vulnerabilities in my hardware? __A:__ Checking the kernel config is not enough to answer this question. I highly recommend using [spectre-meltdown-checker][13] tool maintained by Stéphane Lesimple [@speed47][14].
__Q:__ Can I easily check which kernel versions support some Kconfig option? __A:__ Yes. See the [LKDDb][18] project (Linux Kernel Driver Database) by Giacomo Catenazzi [@cateee][19]. You can use it for the `mainline` or `stable` tree from [kernel.org][20] or for your custom kernel sources.
__Q:__ Why the `CONFIG_GCC_PLUGINS` option is automatically disabled during the kernel compilation? __A:__ It means that your gcc doesn't support plugins. For example, if you have `gcc-14` on Ubuntu, try to install `gcc-14-plugin-dev` package, it should help.

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