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Merge pull request #65585 from delroth/hardened-pti

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nixos/hardened: make pti=on overridable
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Joachim F 2019-07-30 10:35:31 +00:00 committed by GitHub
commit a7d71da84d
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2 changed files with 18 additions and 3 deletions
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5
nixos/modules/profiles/hardened.nix
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@ -26,6 +26,8 @@ with lib;
security.allowSimultaneousMultithreading = mkDefault false;
security.forcePageTableIsolation = mkDefault true;
security.virtualisation.flushL1DataCache = mkDefault "always";
security.apparmor.enable = mkDefault true;
@ -42,9 +44,6 @@ with lib;
# Disable legacy virtual syscalls
"vsyscall=none"
# Enable PTI even if CPU claims to be safe from meltdown
"pti=on"
];
boot.blacklistedKernelModules = [

16
nixos/modules/security/misc.nix
View File

@ -54,6 +54,18 @@ with lib;
'';
};
security.forcePageTableIsolation = mkOption {
type = types.bool;
default = false;
description = ''
Whether to force-enable the Page Table Isolation (PTI) Linux kernel
feature even on CPU models that claim to be safe from Meltdown.
This hardening feature is most beneficial to systems that run untrusted
workloads that rely on address space isolation for security.
'';
};
security.virtualisation.flushL1DataCache = mkOption {
type = types.nullOr (types.enum [ "never" "cond" "always" ]);
default = null;
@ -114,6 +126,10 @@ with lib;
boot.kernelParams = [ "nosmt" ];
})
(mkIf config.security.forcePageTableIsolation {
boot.kernelParams = [ "pti=on" ];
})
(mkIf (config.security.virtualisation.flushL1DataCache != null) {
boot.kernelParams = [ "kvm-intel.vmentry_l1d_flush=${config.security.virtualisation.flushL1DataCache}" ];
})