445 lines
16 KiB
Nix
445 lines
16 KiB
Nix
{ pkgs
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, lanzabooteModule
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}:
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let
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inherit (pkgs) lib system;
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defaultTimeout = 5 * 60; # = 5 minutes
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inherit (pkgs.stdenv.hostPlatform) efiArch;
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efiArchUppercased = lib.toUpper efiArch;
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mkSecureBootTest = { name, machine ? { }, useSecureBoot ? true, useTPM2 ? false, readEfiVariables ? false, testScript }:
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let
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tpmSocketPath = "/tmp/swtpm-sock";
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tpmDeviceModels = {
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x86_64-linux = "tpm-tis";
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aarch64-linux = "tpm-tis-device";
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};
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# Should go to nixpkgs.
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efiVariablesHelpers = ''
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import struct
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SD_LOADER_GUID = "4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"
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def read_raw_variable(var: str) -> bytes:
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attr_var = machine.succeed(f"cat /sys/firmware/efi/efivars/{var}-{SD_LOADER_GUID}").encode('raw_unicode_escape')
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_ = attr_var[:4] # First 4 bytes are attributes according to https://www.kernel.org/doc/html/latest/filesystems/efivarfs.html
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value = attr_var[4:]
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return value
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def read_string_variable(var: str, encoding='utf-16-le') -> str:
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return read_raw_variable(var).decode(encoding).rstrip('\x00')
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# By default, it will read a 4 byte value, read `struct` docs to change the format.
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def assert_variable_uint(var: str, expected: int, format: str = 'I'):
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with subtest(f"Is `{var}` set to {expected} (uint)"):
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value, = struct.unpack(f'<{format}', read_raw_variable(var))
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assert value == expected, f"Unexpected variable value in `{var}`, expected: `{expected}`, actual: `{value}`"
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def assert_variable_string(var: str, expected: str, encoding='utf-16-le'):
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with subtest(f"Is `{var}` correctly set"):
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value = read_string_variable(var, encoding)
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assert value == expected, f"Unexpected variable value in `{var}`, expected: `{expected.encode(encoding)!r}`, actual: `{value.encode(encoding)!r}`"
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def assert_variable_string_contains(var: str, expected_substring: str):
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with subtest(f"Do `{var}` contain expected substrings"):
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value = read_string_variable(var).strip()
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assert expected_substring in value, f"Did not find expected substring in `{var}`, expected substring: `{expected_substring}`, actual value: `{value}`"
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'';
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tpm2Initialization = ''
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import subprocess
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from tempfile import TemporaryDirectory
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# From systemd-initrd-luks-tpm2.nix
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class Tpm:
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def __init__(self):
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self.state_dir = TemporaryDirectory()
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self.start()
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def start(self):
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self.proc = subprocess.Popen(["${pkgs.swtpm}/bin/swtpm",
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"socket",
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"--tpmstate", f"dir={self.state_dir.name}",
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"--ctrl", "type=unixio,path=${tpmSocketPath}",
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"--tpm2",
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])
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# Check whether starting swtpm failed
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try:
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exit_code = self.proc.wait(timeout=0.2)
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if exit_code is not None and exit_code != 0:
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raise Exception("failed to start swtpm")
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except subprocess.TimeoutExpired:
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pass
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"""Check whether the swtpm process exited due to an error"""
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def check(self):
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exit_code = self.proc.poll()
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if exit_code is not None and exit_code != 0:
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raise Exception("swtpm process died")
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tpm = Tpm()
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@polling_condition
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def swtpm_running():
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tpm.check()
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'';
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in
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pkgs.nixosTest {
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inherit name;
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globalTimeout = defaultTimeout;
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testScript = ''
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${lib.optionalString useTPM2 tpm2Initialization}
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${lib.optionalString readEfiVariables efiVariablesHelpers}
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${testScript}
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'';
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nodes.machine = { pkgs, lib, ... }: {
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imports = [
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lanzabooteModule
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machine
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];
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virtualisation = {
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useBootLoader = true;
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useEFIBoot = true;
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efi.OVMF = pkgs.OVMFFull.fd;
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qemu.options = lib.mkIf useTPM2 [
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"-chardev socket,id=chrtpm,path=${tpmSocketPath}"
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"-tpmdev emulator,id=tpm_dev_0,chardev=chrtpm"
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"-device ${tpmDeviceModels.${system}},tpmdev=tpm_dev_0"
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];
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inherit useSecureBoot;
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};
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boot.initrd.availableKernelModules = lib.mkIf useTPM2 [ "tpm_tis" ];
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boot.loader.efi = {
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canTouchEfiVariables = true;
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};
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boot.lanzaboote = {
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enable = true;
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enrollKeys = useSecureBoot;
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pkiBundle = ./fixtures/uefi-keys;
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};
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};
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};
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# Execute a boot test that has an intentionally broken secure boot
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# chain. This test is expected to fail with Secure Boot and should
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# succeed without.
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#
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# Takes a set `path` consisting of a `src` and a `dst` attribute. The file at
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# `src` is copied to `dst` inside th VM. Optionally append some random data
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# ("crap") to the end of the file at `dst`. This is useful to easily change
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# the hash of a file and produce a hash mismatch when booting the stub.
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mkHashMismatchTest = { name, appendCrapGlob, useSecureBoot ? true }: mkSecureBootTest {
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inherit name;
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inherit useSecureBoot;
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testScript = ''
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machine.start()
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machine.succeed("echo some_garbage_to_change_the_hash | tee -a ${appendCrapGlob} > /dev/null")
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machine.succeed("sync")
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machine.crash()
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machine.start()
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'' + (if useSecureBoot then ''
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machine.wait_for_console_text("hash does not match")
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'' else ''
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# Just check that the system came up.
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print(machine.succeed("bootctl", timeout=120))
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'');
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};
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# The initrd is not directly signed. Its hash is embedded into
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# lanzaboote. To make integrity verification fail, we actually have
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# to modify the initrd. Appending crap to the end is a harmless way
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# that would make the kernel still accept it.
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mkModifiedInitrdTest = { name, useSecureBoot }: mkHashMismatchTest {
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inherit name useSecureBoot;
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appendCrapGlob = "/boot/EFI/nixos/initrd-*.efi";
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};
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mkModifiedKernelTest = { name, useSecureBoot }: mkHashMismatchTest {
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inherit name useSecureBoot;
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appendCrapGlob = "/boot/EFI/nixos/kernel-*.efi";
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};
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in
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{
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# TODO: user mode: OK
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# TODO: how to get in: {deployed, audited} mode ?
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basic = mkSecureBootTest {
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name = "lanzaboote";
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testScript = ''
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machine.start()
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assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
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# We want systemd to recognize our PE binaries as true UKIs. systemd has
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# become more picky in the past, so make sure.
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assert "Kernel Type: uki" in machine.succeed("bootctl kernel-inspect /boot/EFI/Linux/nixos-generation-1-*.efi")
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'';
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};
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systemd-initrd = mkSecureBootTest {
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name = "lanzaboote-systemd-initrd";
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machine = { ... }: {
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boot.initrd.systemd.enable = true;
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};
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testScript = ''
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machine.start()
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assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
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'';
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};
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# Test that a secret is appended to the initrd during installation. Smilar to
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# the initrd-secrets test in Nixpkgs:
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# https://github.com/NixOS/nixpkgs/blob/master/nixos/tests/initrd-secrets.nix
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initrd-secrets =
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let
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secret = (pkgs.writeText "oh-so-secure" "uhh-ooh-uhh-security");
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in
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mkSecureBootTest {
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name = "lanzaboote-initrd-secrets";
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machine = { ... }: {
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boot.initrd.secrets = {
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"/test" = secret;
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};
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boot.initrd.postMountCommands = ''
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cp /test /mnt-root/secret-from-initramfs
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'';
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};
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testScript = ''
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machine.start()
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machine.wait_for_unit("multi-user.target")
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machine.succeed("cmp ${secret} /secret-from-initramfs")
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assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
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'';
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};
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# Test that the secrets configured to be appended to the initrd get updated
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# when installing a new generation even if the initrd itself (i.e. its store
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# path) does not change.
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#
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# An unfortunate result of this NixOS feature is that updating the secrets
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# without creating a new initrd might break previous generations. Verify that
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# a new initrd (which is supposed to only differ by the secrets) is created
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# in this case.
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#
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# This tests uses a specialisation to imitate a newer generation. This works
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# because `lzbt` installs the specialisation of a generation AFTER installing
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# the generation itself (thus making the specialisation "newer").
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initrd-secrets-update =
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let
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originalSecret = (pkgs.writeText "oh-so-secure" "uhh-ooh-uhh-security");
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newSecret = (pkgs.writeText "newly-secure" "so-much-better-now");
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in
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mkSecureBootTest {
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name = "lanzaboote-initrd-secrets-update";
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machine = { pkgs, lib, ... }: {
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boot.initrd.secrets = {
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"/test" = lib.mkDefault originalSecret;
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};
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boot.initrd.postMountCommands = ''
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cp /test /mnt-root/secret-from-initramfs
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'';
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specialisation.variant.configuration = {
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boot.initrd.secrets = {
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"/test" = newSecret;
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};
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};
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};
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testScript = ''
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machine.start()
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machine.wait_for_unit("multi-user.target")
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# Assert that only three boot files exists (a single kernel and a two
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# initrds).
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assert int(machine.succeed("ls -1 /boot/EFI/nixos | wc -l")) == 3
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# It is expected that the initrd contains the original secret.
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machine.succeed("cmp ${originalSecret} /secret-from-initramfs")
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machine.succeed("bootctl set-default nixos-generation-1-specialisation-variant-\*.efi")
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machine.succeed("sync")
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machine.crash()
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machine.start()
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machine.wait_for_unit("multi-user.target")
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# It is expected that the initrd of the specialisation contains the new secret.
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machine.succeed("cmp ${newSecret} /secret-from-initramfs")
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'';
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};
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modified-initrd-doesnt-boot-with-secure-boot = mkModifiedInitrdTest {
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name = "modified-initrd-doesnt-boot-with-secure-boot";
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useSecureBoot = true;
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};
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modified-initrd-boots-without-secure-boot = mkModifiedInitrdTest {
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name = "modified-initrd-boots-without-secure-boot";
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useSecureBoot = false;
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};
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modified-kernel-doesnt-boot-with-secure-boot = mkModifiedKernelTest {
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name = "modified-kernel-doesnt-boot-with-secure-boot";
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useSecureBoot = true;
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};
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modified-kernel-boots-without-secure-boot = mkModifiedKernelTest {
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name = "modified-kernel-boots-without-secure-boot";
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useSecureBoot = false;
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};
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specialisation-works = mkSecureBootTest {
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name = "specialisation-still-boot-under-secureboot";
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machine = { pkgs, ... }: {
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specialisation.variant.configuration = {
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environment.systemPackages = [
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pkgs.efibootmgr
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];
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};
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};
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testScript = ''
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machine.start()
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print(machine.succeed("ls -lah /boot/EFI/Linux"))
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# TODO: make it more reliable to find this filename, i.e. read it from somewhere?
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machine.succeed("bootctl set-default nixos-generation-1-specialisation-variant-\*.efi")
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machine.succeed("sync")
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machine.fail("efibootmgr")
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machine.crash()
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machine.start()
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print(machine.succeed("bootctl"))
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# Only the specialisation contains the efibootmgr binary.
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machine.succeed("efibootmgr")
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'';
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};
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# We test if we can install Lanzaboote without Bootspec support.
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synthesis =
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if pkgs.hostPlatform.isAarch64 then
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# FIXME: currently broken on aarch64
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#> mkfs.fat 4.2 (2021-01-31)
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#> setting up /etc...
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#> Enrolling keys to EFI variables...✓
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#> Enrolled keys to the EFI variables!
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#> Installing Lanzaboote to "/boot"...
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#> No bootable generations found! Aborting to avoid unbootable system. Please check for Lanzaboote updates!
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#> [ 2.788390] reboot: Power down
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pkgs.hello
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else
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mkSecureBootTest {
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name = "lanzaboote-synthesis";
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machine = { lib, ... }: {
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boot.bootspec.enable = lib.mkForce false;
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};
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testScript = ''
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machine.start()
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assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
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'';
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};
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systemd-boot-loader-config = mkSecureBootTest {
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name = "lanzaboote-systemd-boot-loader-config";
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machine = {
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boot.loader.timeout = 0;
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boot.loader.systemd-boot.consoleMode = "auto";
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};
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testScript = ''
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machine.start()
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actual_loader_config = machine.succeed("cat /boot/loader/loader.conf").split("\n")
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expected_loader_config = ["timeout 0", "console-mode auto"]
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assert all(cfg in actual_loader_config for cfg in expected_loader_config), \
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f"Expected: {expected_loader_config} is not included in actual config: '{actual_loader_config}'"
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'';
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};
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export-efi-variables = mkSecureBootTest {
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name = "lanzaboote-exports-efi-variables";
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machine.environment.systemPackages = [ pkgs.efibootmgr ];
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readEfiVariables = true;
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testScript = ''
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# We will choose to boot directly on the stub.
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# To perform this trick, we will boot first with systemd-boot.
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# Then, we will add a new boot entry in EFI with higher priority
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# pointing to our stub.
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# Finally, we will reboot.
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# We will also assert that systemd-boot is not running
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# by checking for the sd-boot's specific EFI variables.
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machine.start()
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# By construction, nixos-generation-1.efi is the stub we are interested in.
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# TODO: this should work -- machine.succeed("efibootmgr -d /dev/vda -c -l \\EFI\\Linux\\nixos-generation-1.efi") -- efivars are not persisted
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# across reboots atm?
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# cheat code no 1
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machine.succeed("cp /boot/EFI/Linux/nixos-generation-1-*.efi /boot/EFI/BOOT/BOOT${efiArchUppercased}.EFI")
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machine.succeed("cp /boot/EFI/Linux/nixos-generation-1-*.efi /boot/EFI/systemd/systemd-boot${efiArch}.efi")
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# Let's reboot.
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machine.succeed("sync")
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machine.crash()
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machine.start()
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# This is the sd-boot EFI variable indicator, we should not have it at this point.
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print(machine.execute("bootctl")[1]) # Check if there's incorrect value in the output.
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machine.succeed(
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"test -e /sys/firmware/efi/efivars/LoaderEntrySelected-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f && false || true"
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)
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expected_variables = ["LoaderDevicePartUUID",
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"LoaderImageIdentifier",
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"LoaderFirmwareInfo",
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"LoaderFirmwareType",
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"StubInfo",
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"StubFeatures"
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]
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# Debug all systemd loader specification GUID EFI variables loaded by the current environment.
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print(machine.succeed(f"ls /sys/firmware/efi/efivars/*-{SD_LOADER_GUID}"))
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with subtest("Check if supported variables are exported"):
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for expected_var in expected_variables:
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machine.succeed(f"test -e /sys/firmware/efi/efivars/{expected_var}-{SD_LOADER_GUID}")
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with subtest("Is `StubInfo` correctly set"):
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assert "lanzastub" in read_string_variable("StubInfo"), "Unexpected stub information, provenance is not lanzaboote project!"
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assert_variable_string("LoaderImageIdentifier", "\\EFI\\BOOT\\BOOT${efiArchUppercased}.EFI")
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# TODO: exploit QEMU test infrastructure to pass the good value all the time.
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assert_variable_string("LoaderDevicePartUUID", "1c06f03b-704e-4657-b9cd-681a087a2fdc")
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# OVMF tests are using EDK II tree.
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assert_variable_string_contains("LoaderFirmwareInfo", "EDK II")
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assert_variable_string_contains("LoaderFirmwareType", "UEFI")
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with subtest("Is `StubFeatures` non-zero"):
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assert struct.unpack('<Q', read_raw_variable("StubFeatures")) != 0
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'';
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};
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tpm2-export-efi-variables = mkSecureBootTest {
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name = "lanzaboote-tpm2-exports-efi-variables";
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useTPM2 = true;
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readEfiVariables = true;
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testScript = ''
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machine.start()
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# TODO: the other variables are not yet supported.
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expected_variables = [
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"StubPcrKernelImage"
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]
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# Debug all systemd loader specification GUID EFI variables loaded by the current environment.
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print(machine.succeed(f"ls /sys/firmware/efi/efivars/*-{SD_LOADER_GUID}"))
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with subtest("Check if supported variables are exported"):
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for expected_var in expected_variables:
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machine.succeed(f"test -e /sys/firmware/efi/efivars/{expected_var}-{SD_LOADER_GUID}")
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# "Static" parts of the UKI is measured in PCR11
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assert_variable_uint("StubPcrKernelImage", 11)
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'';
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};
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}
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