X-Git-Url: https://jxself.org/git/?a=blobdiff_plain;f=README.md;h=3ae9147ac0ba3a5f454a17c5c3d37e45546c5116;hb=d361925ba8e7c1f712615e12d4eff678f1f4d59b;hp=9ecd348451b4da528e77060e378eb57ad240ed88;hpb=e5525cb1deb1e701b15d2f0268540efaec817751;p=kconfig-hardened-check.git
diff --git a/README.md b/README.md
index 9ecd348..3ae9147 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,11 @@ I also created the [__Linux Kernel Defence Map__][4], which is a graphical repre
relationships between security hardening features and the corresponding vulnerability classes
or exploitation techniques.
+__Attention!__ Changing Linux kernel security parameters may also affect system performance
+and functionality of userspace software. So for choosing these parameters consider
+the threat model of your Linux-based information system and perform thorough testing
+of its typical workload.
+
## Supported microarchitectures
- X86_64
@@ -89,8 +94,8 @@ CONFIG_DEVMEM | is not set | kspp | cut_atta
## Example output for `Fedora 34` kernel configuration
```
-$ ./bin/kconfig-hardened-check -c /boot/config-5.19.4-200.fc36.x86_64 -l /proc/cmdline
-[+] Kconfig file to check: /boot/config-5.19.4-200.fc36.x86_64
+$ ./bin/kconfig-hardened-check -c /boot/config-5.19.14-200.fc36.x86_64 -l /proc/cmdline
+[+] Kconfig file to check: /boot/config-5.19.14-200.fc36.x86_64
[+] Kernel cmdline file to check: /proc/cmdline
[+] Detected architecture: X86_64
[+] Detected kernel version: 5.19
@@ -130,6 +135,7 @@ CONFIG_SLAB_FREELIST_RANDOM |kconfig| y | kspp | self_p
CONFIG_SHUFFLE_PAGE_ALLOCATOR |kconfig| y | kspp | self_protection | OK
CONFIG_FORTIFY_SOURCE |kconfig| y | kspp | self_protection | OK
CONFIG_DEBUG_LIST |kconfig| y | kspp | self_protection | OK
+CONFIG_DEBUG_VIRTUAL |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_DEBUG_SG |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_DEBUG_CREDENTIALS |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_DEBUG_NOTIFIERS |kconfig| y | kspp | self_protection | FAIL: "is not set"
@@ -140,7 +146,11 @@ CONFIG_WERROR |kconfig| y | kspp | self_p
CONFIG_IOMMU_DEFAULT_DMA_STRICT |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_IOMMU_DEFAULT_PASSTHROUGH |kconfig| is not set | kspp | self_protection | OK
CONFIG_ZERO_CALL_USED_REGS |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_HW_RANDOM_TPM |kconfig| y | kspp | self_protection | OK
+CONFIG_STATIC_USERMODEHELPER |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_SCHED_CORE |kconfig| y | kspp | self_protection | OK
CONFIG_RANDSTRUCT_FULL |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_RANDSTRUCT_PERFORMANCE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_RANDSTRUCT_FULL not "y"
CONFIG_HARDENED_USERCOPY |kconfig| y | kspp | self_protection | OK
CONFIG_HARDENED_USERCOPY_FALLBACK |kconfig| is not set | kspp | self_protection | OK: not found
CONFIG_HARDENED_USERCOPY_PAGESPAN |kconfig| is not set | kspp | self_protection | OK: not found
@@ -150,39 +160,34 @@ CONFIG_MODULE_SIG_SHA512 |kconfig| y | kspp | self_p
CONFIG_MODULE_SIG_FORCE |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_INIT_STACK_ALL_ZERO |kconfig| y | kspp | self_protection | FAIL: "is not set"
CONFIG_INIT_ON_FREE_DEFAULT_ON |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_EFI_DISABLE_PCI_DMA |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_RESET_ATTACK_MITIGATION |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_UBSAN_BOUNDS |kconfig| y | kspp | self_protection | FAIL: not found
+CONFIG_UBSAN_LOCAL_BOUNDS |kconfig| y | kspp | self_protection | FAIL: not found
+CONFIG_UBSAN_TRAP |kconfig| y | kspp | self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
+CONFIG_UBSAN_SANITIZE_ALL |kconfig| y | kspp | self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
CONFIG_GCC_PLUGIN_STACKLEAK |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_STACKLEAK_METRICS |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
+CONFIG_STACKLEAK_RUNTIME_DISABLE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT |kconfig| y | kspp | self_protection | OK
-CONFIG_SCHED_CORE |kconfig| y | kspp | self_protection | OK
+CONFIG_CFI_CLANG |kconfig| y | kspp | self_protection | FAIL: not found
+CONFIG_CFI_PERMISSIVE |kconfig| is not set | kspp | self_protection | FAIL: CONFIG_CFI_CLANG not "y"
CONFIG_DEFAULT_MMAP_MIN_ADDR |kconfig| 65536 | kspp | self_protection | OK
-CONFIG_UBSAN_BOUNDS |kconfig| y |maintainer| self_protection | FAIL: not found
-CONFIG_UBSAN_SANITIZE_ALL |kconfig| y |maintainer| self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
-CONFIG_UBSAN_TRAP |kconfig| y |maintainer| self_protection | FAIL: CONFIG_UBSAN_BOUNDS not "y"
-CONFIG_DEBUG_VIRTUAL |kconfig| y | clipos | self_protection | FAIL: "is not set"
-CONFIG_STATIC_USERMODEHELPER |kconfig| y | clipos | self_protection | FAIL: "is not set"
-CONFIG_EFI_DISABLE_PCI_DMA |kconfig| y | clipos | self_protection | FAIL: "is not set"
+CONFIG_INTEL_IOMMU_DEFAULT_ON |kconfig| y | kspp | self_protection | FAIL: "is not set"
+CONFIG_SLS |kconfig| y | kspp | self_protection | OK
+CONFIG_INTEL_IOMMU_SVM |kconfig| y | kspp | self_protection | OK
+CONFIG_AMD_IOMMU_V2 |kconfig| y | kspp | self_protection | FAIL: "m"
CONFIG_SLAB_MERGE_DEFAULT |kconfig| is not set | clipos | self_protection | OK
-CONFIG_HW_RANDOM_TPM |kconfig| y | clipos | self_protection | OK
-CONFIG_RANDOM_TRUST_BOOTLOADER |kconfig| is not set | clipos | self_protection | FAIL: "y"
-CONFIG_RANDOM_TRUST_CPU |kconfig| is not set | clipos | self_protection | FAIL: "y"
-CONFIG_RANDSTRUCT_PERFORMANCE |kconfig| is not set | clipos | self_protection | FAIL: CONFIG_RANDSTRUCT_FULL not "y"
-CONFIG_STACKLEAK_METRICS |kconfig| is not set | clipos | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
-CONFIG_STACKLEAK_RUNTIME_DISABLE |kconfig| is not set | clipos | self_protection | FAIL: CONFIG_GCC_PLUGIN_STACKLEAK not "y"
-CONFIG_INTEL_IOMMU_DEFAULT_ON |kconfig| y | clipos | self_protection | FAIL: "is not set"
-CONFIG_INTEL_IOMMU_SVM |kconfig| y | clipos | self_protection | OK
-CONFIG_RESET_ATTACK_MITIGATION |kconfig| y | my | self_protection | FAIL: "is not set"
-CONFIG_UBSAN_LOCAL_BOUNDS |kconfig| y | my | self_protection | FAIL: not found
-CONFIG_SLS |kconfig| y | my | self_protection | OK
-CONFIG_AMD_IOMMU_V2 |kconfig| y | my | self_protection | FAIL: "m"
CONFIG_SECURITY |kconfig| y |defconfig | security_policy | OK
CONFIG_SECURITY_YAMA |kconfig| y | kspp | security_policy | OK
CONFIG_SECURITY_LANDLOCK |kconfig| y | kspp | security_policy | OK
CONFIG_SECURITY_SELINUX_DISABLE |kconfig| is not set | kspp | security_policy | OK
-CONFIG_SECURITY_SELINUX_BOOTPARAM |kconfig| is not set | clipos | security_policy | FAIL: "y"
-CONFIG_SECURITY_SELINUX_DEVELOP |kconfig| is not set | clipos | security_policy | FAIL: "y"
-CONFIG_SECURITY_LOCKDOWN_LSM |kconfig| y | clipos | security_policy | OK
-CONFIG_SECURITY_LOCKDOWN_LSM_EARLY |kconfig| y | clipos | security_policy | OK
-CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY|kconfig| y | clipos | security_policy | FAIL: "is not set"
-CONFIG_SECURITY_WRITABLE_HOOKS |kconfig| is not set | my | security_policy | OK: not found
+CONFIG_SECURITY_SELINUX_BOOTPARAM |kconfig| is not set | kspp | security_policy | FAIL: "y"
+CONFIG_SECURITY_SELINUX_DEVELOP |kconfig| is not set | kspp | security_policy | FAIL: "y"
+CONFIG_SECURITY_LOCKDOWN_LSM |kconfig| y | kspp | security_policy | OK
+CONFIG_SECURITY_LOCKDOWN_LSM_EARLY |kconfig| y | kspp | security_policy | OK
+CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY|kconfig| y | kspp | security_policy | FAIL: "is not set"
+CONFIG_SECURITY_WRITABLE_HOOKS |kconfig| is not set | kspp | security_policy | OK: not found
CONFIG_BPF_UNPRIV_DEFAULT_OFF |kconfig| y |defconfig |cut_attack_surface| OK
CONFIG_SECCOMP |kconfig| y |defconfig |cut_attack_surface| OK
CONFIG_SECCOMP_FILTER |kconfig| y |defconfig |cut_attack_surface| OK
@@ -206,6 +211,7 @@ CONFIG_X86_MSR |kconfig| is not set | kspp |cut_att
CONFIG_MODULES |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
CONFIG_DEVMEM |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
CONFIG_IO_STRICT_DEVMEM |kconfig| y | kspp |cut_attack_surface| OK
+CONFIG_LDISC_AUTOLOAD |kconfig| is not set | kspp |cut_attack_surface| FAIL: "y"
CONFIG_LEGACY_VSYSCALL_NONE |kconfig| y | kspp |cut_attack_surface| FAIL: "is not set"
CONFIG_ZSMALLOC_STAT |kconfig| is not set | grsec |cut_attack_surface| OK
CONFIG_PAGE_OWNER |kconfig| is not set | grsec |cut_attack_surface| FAIL: "y"
@@ -263,7 +269,6 @@ CONFIG_X86_IOPL_IOPERM |kconfig| is not set | clipos |cut_att
CONFIG_ACPI_TABLE_UPGRADE |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
CONFIG_EFI_CUSTOM_SSDT_OVERLAYS |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
CONFIG_COREDUMP |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
-CONFIG_LDISC_AUTOLOAD |kconfig| is not set | clipos |cut_attack_surface| FAIL: "y"
CONFIG_X86_INTEL_TSX_MODE_OFF |kconfig| y | clipos |cut_attack_surface| OK
CONFIG_BPF_SYSCALL |kconfig| is not set | lockdown |cut_attack_surface| FAIL: "y"
CONFIG_EFI_TEST |kconfig| is not set | lockdown |cut_attack_surface| FAIL: "m"
@@ -315,6 +320,13 @@ The version format is: __[major_number].[kernel_version].[kernel_patchlevel]__
## Questions and answers
+__Q:__ How all these kernel parameters influence the Linux kernel security?
+
+__A:__ To answer this question, you can use the `kconfig-hardened-check` [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,
@@ -330,13 +342,6 @@ The rationale:
-__Q:__ Why `CONFIG_GCC_PLUGINS` is automatically disabled during the kernel compilation?
-
-__A:__ It means that your gcc doesn't support plugins. For example, if you have `gcc-7` on Ubuntu,
-try to install `gcc-7-plugin-dev` package, it should help.
-
-
-
__Q:__ KSPP and CLIP OS recommend `CONFIG_PANIC_ON_OOPS=y`. Why doesn't this tool do the same?
__A:__ I personally don't support this recommendation because:
@@ -349,6 +354,16 @@ In other cases, the kernel panics, which is similar to `CONFIG_PANIC_ON_OOPS=y`.
+__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 options?
__A:__ Ike Devolder [@BlackIkeEagle][7] made some performance tests and described the results in [this article][8].
@@ -363,20 +378,17 @@ You can use it for the `mainline` or `stable` tree from [kernel.org][20] or for
-__Q:__ Why enabling `CONFIG_STATIC_USERMODEHELPER` breaks various things in my GNU/Linux system?
-Do I really need that feature?
+__Q:__ Does my kernel have all those mitigations of Transient Execution Vulnerabilities in my hardware?
-__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].
+__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:__ Does my kernel have all those mitigations of Transient Execution Vulnerabilities in my hardware?
+__Q:__ Why the `CONFIG_GCC_PLUGINS` option is automatically disabled during the kernel compilation?
-__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].
+__A:__ It means that your gcc doesn't support plugins. For example, if you have `gcc-7` on Ubuntu,
+try to install `gcc-7-plugin-dev` package, it should help.
[1]: http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
@@ -402,3 +414,4 @@ I highly recommend using [spectre-meltdown-checker][13] tool maintained by Stép
[21]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/66
[22]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/56
[23]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues?q=label%3Akernel_maintainer_feedback
+[24]: https://github.com/a13xp0p0v/kconfig-hardened-check#motivation