#!/usr/bin/python3
"""
-This tool helps me to check Linux kernel options against
-my security hardening preferences for X86_64, ARM64, X86_32, and ARM.
-Let the computers do their job!
+This tool is for checking the security hardening options of the Linux kernel.
Author: Alexander Popov <alex.popov@linux.com>
This module contains knowledge for checks.
"""
-# N.B. Hardening sysctls:
-# kernel.kptr_restrict=2 (or 1?)
-# kernel.dmesg_restrict=1 (also see the kconfig option)
-# kernel.perf_event_paranoid=2 (or 3 with a custom patch, see https://lwn.net/Articles/696216/)
-# kernel.kexec_load_disabled=1
-# kernel.yama.ptrace_scope=3
-# user.max_user_namespaces=0
-# what about bpf_jit_enable?
-# kernel.unprivileged_bpf_disabled=1
-# net.core.bpf_jit_harden=2
-# vm.unprivileged_userfaultfd=0
-# (at first, it disabled unprivileged userfaultfd,
-# and since v5.11 it enables unprivileged userfaultfd for user-mode only)
-# vm.mmap_min_addr has a good value
-# dev.tty.ldisc_autoload=0
-# fs.protected_symlinks=1
-# fs.protected_hardlinks=1
-# fs.protected_fifos=2
-# fs.protected_regular=2
-# fs.suid_dumpable=0
-# kernel.modules_disabled=1
-# kernel.randomize_va_space=2
-# nosmt sysfs control file
-# dev.tty.legacy_tiocsti=0
-# vm.mmap_rnd_bits=max (?)
-# kernel.sysrq=0
-#
-# Think of these boot params:
-# module.sig_enforce=1
-# lockdown=confidentiality
-# mce=0
-# nosmt=force
-# intel_iommu=on
-# amd_iommu=on
-# efi=disable_early_pci_dma
-
# pylint: disable=missing-function-docstring,line-too-long,invalid-name
# pylint: disable=too-many-branches,too-many-statements
-from .engine import KconfigCheck, CmdlineCheck, VersionCheck, OR, AND
+from .engine import KconfigCheck, CmdlineCheck, SysctlCheck, VersionCheck, OR, AND
def add_kconfig_checks(l, arch):
+ assert(arch), 'empty arch'
+
# Calling the KconfigCheck class constructor:
# KconfigCheck(reason, decision, name, expected)
#
if arch == 'X86_64':
l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
+ l += [KconfigCheck('self_protection', 'defconfig', 'X86_KERNEL_IBT', 'y')]
l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
iommu_support_is_set)]
l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
l += [hardened_usercopy_is_set]
l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
- hardened_usercopy_is_set)]
+ hardened_usercopy_is_set)] # usercopy whitelist violations should be prohibited
l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
- hardened_usercopy_is_set)]
+ hardened_usercopy_is_set)] # this debugging for HARDENED_USERCOPY is not needed for security
l += [AND(KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y'),
gcc_plugins_support_is_set)]
l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
- l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
devmem_not_set)] # refers to LOCKDOWN
l += [AND(KconfigCheck('cut_attack_surface', 'kspp', 'LDISC_AUTOLOAD', 'is not set'),
KconfigCheck('cut_attack_surface', 'kspp', 'LDISC_AUTOLOAD', 'is present'))]
+ if arch in ('X86_64', 'X86_32'):
+ l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
+ # CONFIG_COMPAT_VDSO disabled ASLR of vDSO only on X86_64 and X86_32;
+ # on ARM64 this option has different meaning
if arch == 'ARM':
l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
devmem_not_set)] # refers to LOCKDOWN
l += [KconfigCheck('cut_attack_surface', 'my', 'KGDB', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'my', 'AIO', 'is not set')]
l += [KconfigCheck('cut_attack_surface', 'my', 'CORESIGHT', 'is not set')]
+ l += [KconfigCheck('cut_attack_surface', 'my', 'XFS_SUPPORT_V4', 'is not set')]
l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
modules_not_set)]
def add_cmdline_checks(l, arch):
+ assert(arch), 'empty arch'
+
# Calling the CmdlineCheck class constructor:
# CmdlineCheck(reason, decision, name, expected)
#
l += [CmdlineCheck('self_protection', 'defconfig', 'arm64.nobti', 'is not set')]
l += [CmdlineCheck('self_protection', 'defconfig', 'arm64.nopauth', 'is not set')]
l += [CmdlineCheck('self_protection', 'defconfig', 'arm64.nomte', 'is not set')]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spectre_v2', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'spectre_v2', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spectre_v2_user', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'spectre_v2_user', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spec_store_bypass_disable', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'spec_store_bypass_disable', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'l1tf', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'l1tf', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'mds', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'mds', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'tsx_async_abort', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'tsx_async_abort', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'srbds', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'srbds', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'mmio_stale_data', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'mmio_stale_data', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'retbleed', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'retbleed', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'kpti', 'is not off'),
- AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
- CmdlineCheck('self_protection', 'defconfig', 'kpti', 'is not set')))]
+ if arch in ('X86_64', 'X86_32'):
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spectre_v2', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'spectre_v2', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spectre_v2_user', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'spectre_v2_user', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'spec_store_bypass_disable', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'spec_store_bypass_disable', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'l1tf', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'l1tf', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'mds', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'mds', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'tsx_async_abort', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'tsx_async_abort', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'srbds', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'srbds', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'mmio_stale_data', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'mmio_stale_data', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'retbleed', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'retbleed', 'is not set')))]
if arch == 'ARM64':
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'kpti', 'is not off'),
+ AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
+ CmdlineCheck('self_protection', 'defconfig', 'kpti', 'is not set')))]
l += [OR(CmdlineCheck('self_protection', 'defconfig', 'ssbd', 'kernel'),
CmdlineCheck('self_protection', 'my', 'ssbd', 'force-on'),
AND(CmdlineCheck('self_protection', 'kspp', 'mitigations', 'auto,nosmt'),
AND(KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y'),
CmdlineCheck('self_protection', 'defconfig', 'rodata', 'is not set')))]
else:
- l += [OR(CmdlineCheck('self_protection', 'defconfig', 'rodata', '1'),
+ l += [OR(CmdlineCheck('self_protection', 'defconfig', 'rodata', 'on'),
CmdlineCheck('self_protection', 'defconfig', 'rodata', 'is not set'))]
# 'self_protection', 'kspp'
AND(CmdlineCheck('self_protection', 'kspp', 'page_poison', '1'),
KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'),
CmdlineCheck('self_protection', 'kspp', 'slub_debug', 'P')))]
- l += [OR(CmdlineCheck('self_protection', 'kspp', 'iommu.strict', '1'),
- AND(KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y'),
- CmdlineCheck('self_protection', 'kspp', 'iommu.strict', 'is not set')))]
- l += [OR(CmdlineCheck('self_protection', 'kspp', 'iommu.passthrough', '0'),
- AND(KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_PASSTHROUGH', 'is not set'),
- CmdlineCheck('self_protection', 'kspp', 'iommu.passthrough', 'is not set')))]
# The cmdline checks compatible with the kconfig recommendations of the KSPP project...
l += [OR(CmdlineCheck('self_protection', 'kspp', 'hardened_usercopy', '1'),
AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y'),
CmdlineCheck('self_protection', 'kspp', 'slab_common.usercopy_fallback', 'is not set')))]
# ... the end
if arch in ('X86_64', 'ARM64', 'X86_32'):
+ l += [OR(CmdlineCheck('self_protection', 'kspp', 'iommu.strict', '1'),
+ AND(KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y'),
+ CmdlineCheck('self_protection', 'kspp', 'iommu.strict', 'is not set')))]
+ l += [OR(CmdlineCheck('self_protection', 'kspp', 'iommu.passthrough', '0'),
+ AND(KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_PASSTHROUGH', 'is not set'),
+ CmdlineCheck('self_protection', 'kspp', 'iommu.passthrough', 'is not set')))]
l += [OR(CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', '1'),
AND(KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y'),
CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', 'is not set')))]
KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set'),
AND(KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y'),
CmdlineCheck('cut_attack_surface', 'kspp', 'vsyscall', 'is not set')))]
+ l += [OR(CmdlineCheck('cut_attack_surface', 'my', 'vdso32', '1'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso32', '0'),
+ AND(KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso32', 'is not set')))] # the vdso32 parameter must not be 2
+ if arch == 'X86_32':
+ l += [OR(CmdlineCheck('cut_attack_surface', 'my', 'vdso32', '1'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso', '1'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso32', '0'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso', '0'),
+ AND(KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso32', 'is not set'),
+ CmdlineCheck('cut_attack_surface', 'my', 'vdso', 'is not set')))] # the vdso and vdso32 parameters must not be 2
# 'cut_attack_surface', 'grsec'
# The cmdline checks compatible with the kconfig options disabled by grsecurity...
'srbds', # See srbds_parse_cmdline() in arch/x86/kernel/cpu/bugs.c
'mmio_stale_data', # See mmio_stale_data_parse_cmdline() in arch/x86/kernel/cpu/bugs.c
'retbleed', # See retbleed_parse_cmdline() in arch/x86/kernel/cpu/bugs.c
+ 'rodata', # See set_debug_rodata() in init/main.c
+ 'ssbd', # See parse_spectre_v4_param() in arch/arm64/kernel/proton-pack.c
+ 'slub_debug', # See setup_slub_debug() in mm/slub.c
+ 'iommu', # See iommu_setup() in arch/x86/kernel/pci-dma.c
+ 'vsyscall', # See vsyscall_setup() in arch/x86/entry/vsyscall/vsyscall_64.c
+ 'vdso32', # See vdso32_setup() in arch/x86/entry/vdso/vdso32-setup.c
+ 'vdso', # See vdso32_setup() in arch/x86/entry/vdso/vdso32-setup.c
'tsx' # See tsx_init() in arch/x86/kernel/cpu/tsx.c
]
return value
# Implement a limited part of the kstrtobool() logic
- if value in ('1', 'on', 'On', 'ON', 'y', 'Y', 'yes', 'Yes', 'YES'):
+ if value.lower() in ('1', 'on', 'y', 'yes', 't', 'true'):
return '1'
- if value in ('0', 'off', 'Off', 'OFF', 'n', 'N', 'no', 'No', 'NO'):
+ if value.lower() in ('0', 'off', 'n', 'no', 'f', 'false'):
return '0'
# Preserve unique values
return value
+
+
+# TODO: draft of security hardening sysctls:
+# kernel.kptr_restrict=2 (or 1?)
+# kernel.yama.ptrace_scope=3
+# what about bpf_jit_enable?
+# vm.unprivileged_userfaultfd=0
+# (at first, it disabled unprivileged userfaultfd,
+# and since v5.11 it enables unprivileged userfaultfd for user-mode only)
+# vm.mmap_min_addr has a good value
+# fs.protected_symlinks=1
+# fs.protected_hardlinks=1
+# fs.protected_fifos=2
+# fs.protected_regular=2
+# fs.suid_dumpable=0
+# kernel.modules_disabled=1
+# kernel.randomize_va_space=2
+# nosmt sysfs control file
+# dev.tty.legacy_tiocsti=0
+# vm.mmap_rnd_bits=max (?)
+# kernel.sysrq=0
+# abi.vsyscall32 (any value except 2)
+# kernel.oops_limit (think about a proper value)
+# kernel.warn_limit (think about a proper value)
+# net.ipv4.tcp_syncookies=1 (?)
+
+def add_sysctl_checks(l, arch):
+# This function may be called with arch=None
+
+# Calling the SysctlCheck class constructor:
+# SysctlCheck(reason, decision, name, expected)
+
+ l += [SysctlCheck('self_protection', 'kspp', 'net.core.bpf_jit_harden', '2')]
+
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.dmesg_restrict', '1')]
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.perf_event_paranoid', '3')] # with a custom patch, see https://lwn.net/Articles/696216/
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.kexec_load_disabled', '1')]
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'user.max_user_namespaces', '0')]
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'dev.tty.ldisc_autoload', '0')]
+ l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.unprivileged_bpf_disabled', '1')]
projects / kconfig-hardened-check.git / blobdiff