Improve the COMPAT_VDSO check

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

diff --git a/kconfig_hardened_check/checks.py b/kconfig_hardened_check/checks.py
index b24b9f8323cb59de2efeada437664fd0f1fa2bf2..43a4c648bba53fed54727838f518e6b4ed616d3f 100644 (file)
--- a/kconfig_hardened_check/checks.py
+++ b/kconfig_hardened_check/checks.py
@@ -34,6 +34,8 @@ This module contains knowledge for checks.
 #    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
@@ -286,7 +288,6 @@ def add_kconfig_checks(l, arch):
     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
@@ -306,8 +307,10 @@ def add_kconfig_checks(l, arch):
              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 == 'X86_64':
-        l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
+    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
@@ -366,7 +369,6 @@ def add_kconfig_checks(l, arch):
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
-    l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
@@ -376,6 +378,11 @@ def add_kconfig_checks(l, arch):
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
     l += [KconfigCheck('cut_attack_surface', 'clipos', 'COREDUMP', 'is not set')] # cut userspace attack surface
 #   l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
+    if arch == 'X86_64':
+        l += [OR(KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set'),
+                 KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y'))]
+                 # disabling X86_VSYSCALL_EMULATION turns vsyscall off completely,
+                 # and LEGACY_VSYSCALL_NONE can be changed at boot time via the cmdline parameter
 
     # 'cut_attack_surface', 'lockdown'
     l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
@@ -404,10 +411,7 @@ def add_kconfig_checks(l, arch):
         l += [KconfigCheck('harden_userspace', 'defconfig', 'ARM64_BTI', 'y')]
     if arch in ('ARM', 'X86_32'):
         l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
-    if arch in ('X86_64', 'ARM64'):
-        l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
-    if arch in ('X86_32', 'ARM'):
-        l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
+    l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', 'MAX')] # 'MAX' value is refined using ARCH_MMAP_RND_BITS_MAX
 
 
 def add_cmdline_checks(l, arch):
@@ -538,6 +542,7 @@ def add_cmdline_checks(l, arch):
     # 'cut_attack_surface', 'kspp'
     if arch == 'X86_64':
         l += [OR(CmdlineCheck('cut_attack_surface', 'kspp', 'vsyscall', 'none'),
+                 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')))]