Fix the reason and decision of the KEXEC_CORE check

[kconfig-hardened-check.git] / kernel_hardening_checker / checks.py

diff --git a/kernel_hardening_checker/checks.py b/kernel_hardening_checker/checks.py
index 5ec19cc5b7b7ad4a77a370d9c3671d579750eabd..56efe2570e72e73c75aa96dd41082ba84ea95164 100644 (file)
--- a/kernel_hardening_checker/checks.py
+++ b/kernel_hardening_checker/checks.py
@@ -26,6 +26,9 @@ def add_kconfig_checks(l, arch):
     efi_not_set = KconfigCheck('-', '-', 'EFI', 'is not set')
     cc_is_gcc = KconfigCheck('-', '-', 'CC_IS_GCC', 'y') # exists since v4.18
     cc_is_clang = KconfigCheck('-', '-', 'CC_IS_CLANG', 'y') # exists since v4.18
+    if arch in ('X86_64', 'X86_32'):
+        cpu_sup_amd_not_set = KconfigCheck('-', '-', 'CPU_SUP_AMD', 'is not set')
+        cpu_sup_intel_not_set = KconfigCheck('-', '-', 'CPU_SUP_INTEL', 'is not set')
 
     modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set') # radical, but may be useful in some cases
     devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
@@ -65,22 +68,26 @@ def add_kconfig_checks(l, arch):
         l += [KconfigCheck('self_protection', 'defconfig', 'DEBUG_WX', 'y')]
         l += [KconfigCheck('self_protection', 'defconfig', 'WERROR', 'y')]
         l += [KconfigCheck('self_protection', 'defconfig', 'X86_MCE', 'y')]
-        l += [KconfigCheck('self_protection', 'defconfig', 'X86_MCE_INTEL', 'y')]
-        l += [KconfigCheck('self_protection', 'defconfig', 'X86_MCE_AMD', 'y')]
         l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
         l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
         microcode_is_set = KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')
         l += [microcode_is_set] # is needed for mitigating CPU bugs
         l += [OR(KconfigCheck('self_protection', 'defconfig', 'MICROCODE_INTEL', 'y'),
+                 cpu_sup_intel_not_set,
                  AND(microcode_is_set,
                      VersionCheck((6, 6, 0))))] # MICROCODE_INTEL was included in MICROCODE since v6.6
         l += [OR(KconfigCheck('self_protection', 'defconfig', 'MICROCODE_AMD', 'y'),
+                 cpu_sup_amd_not_set,
                  AND(microcode_is_set,
                      VersionCheck((6, 6, 0))))] # MICROCODE_AMD was included in MICROCODE since v6.6
         l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y'),
                  VersionCheck((5, 19, 0)))] # X86_SMAP is enabled by default since v5.19
         l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
                  KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
+        l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_MCE_INTEL', 'y'),
+                 cpu_sup_intel_not_set)]
+        l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_MCE_AMD', 'y'),
+                 cpu_sup_amd_not_set)]
     if arch in ('ARM64', 'ARM'):
         l += [KconfigCheck('self_protection', 'defconfig', 'HW_RANDOM_TPM', 'y')]
         l += [KconfigCheck('self_protection', 'defconfig', 'IOMMU_DEFAULT_DMA_STRICT', 'y')]
@@ -90,7 +97,8 @@ def add_kconfig_checks(l, arch):
         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 += [KconfigCheck('self_protection', 'defconfig', 'CPU_SRSO', 'y')]
+        l += [OR(KconfigCheck('self_protection', 'defconfig', 'CPU_SRSO', 'y'),
+                 cpu_sup_amd_not_set)]
         l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
                   iommu_support_is_set)]
         l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
@@ -274,7 +282,8 @@ def add_kconfig_checks(l, arch):
         l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
                  devmem_not_set)] # refers to LOCKDOWN
     if arch in ('X86_64', 'X86_32'):
-        l += [KconfigCheck('cut_attack_surface', 'defconfig', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
+        l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'X86_INTEL_TSX_MODE_OFF', 'y'),
+                 cpu_sup_intel_not_set)] # tsx=off
 
     # 'cut_attack_surface', 'kspp'
     l += [KconfigCheck('cut_attack_surface', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
@@ -395,9 +404,11 @@ def add_kconfig_checks(l, arch):
     l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'KGDB', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'CORESIGHT', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'XFS_SUPPORT_V4', 'is not set')]
+    l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'MODULE_FORCE_LOAD', 'is not set')]
+    l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'BLK_DEV_WRITE_MOUNTED', 'is not set')]
     l += [OR(KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'TRIM_UNUSED_KSYMS', 'y'),
              modules_not_set)]
-    l += [KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'MODULE_FORCE_LOAD', 'is not set')]
+
 
     # 'harden_userspace'
     if arch == 'ARM64':
@@ -546,9 +557,12 @@ def add_cmdline_checks(l, arch):
 
     # 'cut_attack_surface', 'defconfig'
     if arch in ('X86_64', 'X86_32'):
+        tsx_not_set = CmdlineCheck('cut_attack_surface', 'defconfig', 'tsx', 'is not set')
         l += [OR(CmdlineCheck('cut_attack_surface', 'defconfig', 'tsx', 'off'),
                  AND(KconfigCheck('cut_attack_surface', 'defconfig', 'X86_INTEL_TSX_MODE_OFF', 'y'),
-                     CmdlineCheck('cut_attack_surface', 'defconfig', 'tsx', 'is not set')))]
+                     tsx_not_set),
+                 AND(KconfigCheck('-', '-', 'CPU_SUP_INTEL', 'is not set'),
+                     tsx_not_set))]
 
     # 'cut_attack_surface', 'kspp'
     l += [CmdlineCheck('cut_attack_surface', 'kspp', 'nosmt', 'is present')] # slow (high performance penalty)
@@ -577,6 +591,9 @@ def add_cmdline_checks(l, arch):
 
     # 'cut_attack_surface', 'a13xp0p0v'
     l += [CmdlineCheck('cut_attack_surface', 'a13xp0p0v', 'sysrq_always_enabled', 'is not set')]
+    l += [OR(CmdlineCheck('cut_attack_surface', 'a13xp0p0v', 'bdev_allow_write_mounted', '0'),
+             AND(KconfigCheck('cut_attack_surface', 'a13xp0p0v', 'BLK_DEV_WRITE_MOUNTED', 'is not set'),
+                 CmdlineCheck('cut_attack_surface', 'a13xp0p0v', 'bdev_allow_write_mounted', 'is not set')))]
     if arch == 'X86_64':
         l += [OR(CmdlineCheck('cut_attack_surface', 'a13xp0p0v', 'ia32_emulation', '0'),
                  KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set'),
@@ -646,21 +663,34 @@ def add_sysctl_checks(l, _arch):
 # Calling the SysctlCheck class constructor:
 #   SysctlCheck(reason, decision, name, expected)
 
-    l += [SysctlCheck('self_protection', 'kspp', 'net.core.bpf_jit_harden', '2')]
+    # Use an omnipresent kconfig symbol to see if we have a kconfig file for checking
+    have_config_file = KconfigCheck('-', '-', 'LOCALVERSION', 'is present')
+
+    l += [OR(SysctlCheck('self_protection', 'kspp', 'net.core.bpf_jit_harden', '2'),
+             AND(KconfigCheck('-', '-', 'BPF_JIT', 'is not set'),
+                 have_config_file))]
 
     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 += [OR(SysctlCheck('cut_attack_surface', 'kspp', 'kernel.kexec_load_disabled', '1'),
+             AND(KconfigCheck('-', '-', 'KEXEC_CORE', 'is not set'),
+                 have_config_file))]
     l += [SysctlCheck('cut_attack_surface', 'kspp', 'user.max_user_namespaces', '0')] # may break the upower daemon in Ubuntu
     l += [SysctlCheck('cut_attack_surface', 'kspp', 'dev.tty.ldisc_autoload', '0')]
-    l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.unprivileged_bpf_disabled', '1')]
+    l += [OR(SysctlCheck('cut_attack_surface', 'kspp', 'kernel.unprivileged_bpf_disabled', '1'),
+             AND(KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set'),
+                 have_config_file))]
     l += [SysctlCheck('cut_attack_surface', 'kspp', 'kernel.kptr_restrict', '2')]
     l += [SysctlCheck('cut_attack_surface', 'kspp', 'dev.tty.legacy_tiocsti', '0')]
-    l += [SysctlCheck('cut_attack_surface', 'kspp', 'vm.unprivileged_userfaultfd', '0')]
+    l += [OR(SysctlCheck('cut_attack_surface', 'kspp', 'vm.unprivileged_userfaultfd', '0'),
+             AND(KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set'),
+                 have_config_file))]
           # At first, it disabled unprivileged userfaultfd,
           # and since v5.11 it enables unprivileged userfaultfd for user-mode only.
 
-    l += [SysctlCheck('cut_attack_surface', 'clipos', 'kernel.modules_disabled', '1')] # radical, but may be useful in some cases
+    l += [OR(SysctlCheck('cut_attack_surface', 'clipos', 'kernel.modules_disabled', '1'), # radical, but may be useful in some cases
+             AND(KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set'),
+                 have_config_file))]
 
     l += [SysctlCheck('harden_userspace', 'kspp', 'fs.protected_symlinks', '1')]
     l += [SysctlCheck('harden_userspace', 'kspp', 'fs.protected_hardlinks', '1')]