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a432668acf
The priviledge separation mode has several downsides:
- it's incompatible with alternative memory allocators, including
graphene-hardened;
- it needs an unreleased patch to fix a crash;
- it results in none less than 6 subprocesses running at any time,
increasing the memory usage;
- the privileged process (albeit not doing any networking related
tasks) is still running as root, so it has complete access to the
system.
Let's disable this by default and instead run dhcpcd as an unpriviledge
user with only the necessary capabilities.
101 lines
3.3 KiB
Nix
101 lines
3.3 KiB
Nix
import ./make-test-python.nix ({ pkgs, ... } : {
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name = "hardened";
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meta = with pkgs.lib.maintainers; {
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maintainers = [ joachifm ];
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};
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nodes.machine =
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{ lib, pkgs, config, ... }:
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{ users.users.alice = { isNormalUser = true; extraGroups = [ "proc" ]; };
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users.users.sybil = { isNormalUser = true; group = "wheel"; };
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imports = [ ../modules/profiles/hardened.nix ];
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environment.memoryAllocator.provider = "graphene-hardened";
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nix.settings.sandbox = false;
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virtualisation.emptyDiskImages = [ 4096 ];
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boot.initrd.postDeviceCommands = ''
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${pkgs.dosfstools}/bin/mkfs.vfat -n EFISYS /dev/vdb
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'';
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virtualisation.fileSystems = {
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"/efi" = {
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device = "/dev/disk/by-label/EFISYS";
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fsType = "vfat";
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options = [ "noauto" ];
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};
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};
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boot.extraModulePackages =
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pkgs.lib.optional (pkgs.lib.versionOlder config.boot.kernelPackages.kernel.version "5.6")
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config.boot.kernelPackages.wireguard;
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boot.kernelModules = [ "wireguard" ];
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};
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testScript =
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let
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hardened-malloc-tests = pkgs.graphene-hardened-malloc.ld-preload-tests;
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in
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''
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machine.wait_for_unit("multi-user.target")
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with subtest("AppArmor profiles are loaded"):
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machine.succeed("systemctl status apparmor.service")
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# AppArmor securityfs
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with subtest("AppArmor securityfs is mounted"):
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machine.succeed("mountpoint -q /sys/kernel/security")
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machine.succeed("cat /sys/kernel/security/apparmor/profiles")
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# Test loading out-of-tree modules
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with subtest("Out-of-tree modules can be loaded"):
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machine.succeed("grep -Fq wireguard /proc/modules")
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# Test kernel module hardening
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with subtest("No more kernel modules can be loaded"):
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# note: this better a be module we normally wouldn't load ...
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machine.wait_for_unit("disable-kernel-module-loading.service")
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machine.fail("modprobe dccp")
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# Test userns
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with subtest("User namespaces are restricted"):
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machine.succeed("unshare --user true")
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machine.fail("su -l alice -c 'unshare --user true'")
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# Test dmesg restriction
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with subtest("Regular users cannot access dmesg"):
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machine.fail("su -l alice -c dmesg")
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# Test access to kcore
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with subtest("Kcore is inaccessible as root"):
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machine.fail("cat /proc/kcore")
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# Test deferred mount
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with subtest("Deferred mounts work"):
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machine.fail("mountpoint -q /efi") # was deferred
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machine.execute("mkdir -p /efi")
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machine.succeed("mount /dev/disk/by-label/EFISYS /efi")
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machine.succeed("mountpoint -q /efi") # now mounted
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# Test Nix dæmon usage
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with subtest("nix-daemon cannot be used by all users"):
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machine.fail("su -l nobody -s /bin/sh -c 'nix --extra-experimental-features nix-command ping-store'")
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machine.succeed("su -l alice -c 'nix --extra-experimental-features nix-command ping-store'")
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# Test kernel image protection
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with subtest("The kernel image is protected"):
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machine.fail("systemctl hibernate")
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machine.fail("systemctl kexec")
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with subtest("The hardened memory allocator works"):
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machine.succeed("${hardened-malloc-tests}/bin/run-tests")
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'';
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})
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