lanzaboote/nix/tests/lanzaboote.nix

454 lines
17 KiB
Nix

{ pkgs
, lanzabooteModule
}:
let
inherit (pkgs) lib system;
defaultTimeout = 5 * 60; # = 5 minutes
mkSecureBootTest = { name, machine ? { }, useSecureBoot ? true, useTPM2 ? false, readEfiVariables ? false, testScript }:
let
tpmSocketPath = "/tmp/swtpm-sock";
tpmDeviceModels = {
x86_64-linux = "tpm-tis";
aarch64-linux = "tpm-tis-device";
};
# Should go to nixpkgs.
efiVariablesHelpers = ''
import struct
SD_LOADER_GUID = "4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"
def read_raw_variable(var: str) -> bytes:
attr_var = machine.succeed(f"cat /sys/firmware/efi/efivars/{var}-{SD_LOADER_GUID}").encode('raw_unicode_escape')
_ = attr_var[:4] # First 4 bytes are attributes according to https://www.kernel.org/doc/html/latest/filesystems/efivarfs.html
value = attr_var[4:]
return value
def read_string_variable(var: str, encoding='utf-16-le') -> str:
return read_raw_variable(var).decode(encoding).rstrip('\x00')
# By default, it will read a 4 byte value, read `struct` docs to change the format.
def assert_variable_uint(var: str, expected: int, format: str = 'I'):
with subtest(f"Is `{var}` set to {expected} (uint)"):
value, = struct.unpack(f'<{format}', read_raw_variable(var))
assert value == expected, f"Unexpected variable value in `{var}`, expected: `{expected}`, actual: `{value}`"
def assert_variable_string(var: str, expected: str, encoding='utf-16-le'):
with subtest(f"Is `{var}` correctly set"):
value = read_string_variable(var, encoding)
assert value == expected, f"Unexpected variable value in `{var}`, expected: `{expected.encode(encoding)!r}`, actual: `{value.encode(encoding)!r}`"
def assert_variable_string_contains(var: str, expected_substring: str):
with subtest(f"Do `{var}` contain expected substrings"):
value = read_string_variable(var).strip()
assert expected_substring in value, f"Did not find expected substring in `{var}`, expected substring: `{expected_substring}`, actual value: `{value}`"
'';
tpm2Initialization = ''
import subprocess
from tempfile import TemporaryDirectory
# From systemd-initrd-luks-tpm2.nix
class Tpm:
def __init__(self):
self.state_dir = TemporaryDirectory()
self.start()
def start(self):
self.proc = subprocess.Popen(["${pkgs.swtpm}/bin/swtpm",
"socket",
"--tpmstate", f"dir={self.state_dir.name}",
"--ctrl", "type=unixio,path=${tpmSocketPath}",
"--tpm2",
])
# Check whether starting swtpm failed
try:
exit_code = self.proc.wait(timeout=0.2)
if exit_code is not None and exit_code != 0:
raise Exception("failed to start swtpm")
except subprocess.TimeoutExpired:
pass
"""Check whether the swtpm process exited due to an error"""
def check(self):
exit_code = self.proc.poll()
if exit_code is not None and exit_code != 0:
raise Exception("swtpm process died")
tpm = Tpm()
@polling_condition
def swtpm_running():
tpm.check()
'';
in
pkgs.nixosTest {
inherit name;
globalTimeout = defaultTimeout;
testScript = ''
${lib.optionalString useTPM2 tpm2Initialization}
${lib.optionalString readEfiVariables efiVariablesHelpers}
${testScript}
'';
nodes.machine = { pkgs, lib, ... }: {
imports = [
lanzabooteModule
machine
];
virtualisation = {
useBootLoader = true;
useEFIBoot = true;
# We actually only want to enable features in OVMF, but at
# the moment edk2 202308 is also broken. So we downgrade it
# here as well. How painful!
#
# See #240.
efi.OVMF =
let
edk2Version = "202305";
edk2Src = pkgs.fetchFromGitHub {
owner = "tianocore";
repo = "edk2";
rev = "edk2-stable${edk2Version}";
fetchSubmodules = true;
hash = "sha256-htOvV43Hw5K05g0SF3po69HncLyma3BtgpqYSdzRG4s=";
};
edk2 = pkgs.edk2.overrideAttrs (old: rec {
version = edk2Version;
src = edk2Src;
});
in
(pkgs.OVMF.override {
secureBoot = useSecureBoot;
tpmSupport = useTPM2; # This is needed otherwise OVMF won't initialize the TPM2 protocol.
edk2 = edk2;
}).overrideAttrs (old: {
src = edk2Src;
});
qemu.options = lib.mkIf useTPM2 [
"-chardev socket,id=chrtpm,path=${tpmSocketPath}"
"-tpmdev emulator,id=tpm_dev_0,chardev=chrtpm"
"-device ${tpmDeviceModels.${system}},tpmdev=tpm_dev_0"
];
inherit useSecureBoot;
};
boot.initrd.availableKernelModules = lib.mkIf useTPM2 [ "tpm_tis" ];
boot.loader.efi = {
canTouchEfiVariables = true;
};
boot.lanzaboote = {
enable = true;
enrollKeys = lib.mkDefault true;
pkiBundle = ./fixtures/uefi-keys;
};
};
};
# Execute a boot test that has an intentionally broken secure boot
# chain. This test is expected to fail with Secure Boot and should
# succeed without.
#
# Takes a set `path` consisting of a `src` and a `dst` attribute. The file at
# `src` is copied to `dst` inside th VM. Optionally append some random data
# ("crap") to the end of the file at `dst`. This is useful to easily change
# the hash of a file and produce a hash mismatch when booting the stub.
mkHashMismatchTest = { name, appendCrapGlob, useSecureBoot ? true }: mkSecureBootTest {
inherit name;
inherit useSecureBoot;
testScript = ''
machine.start()
machine.succeed("echo some_garbage_to_change_the_hash | tee -a ${appendCrapGlob} > /dev/null")
machine.succeed("sync")
machine.crash()
machine.start()
'' + (if useSecureBoot then ''
machine.wait_for_console_text("hash does not match")
'' else ''
# Just check that the system came up.
print(machine.succeed("bootctl", timeout=120))
'');
};
# The initrd is not directly signed. Its hash is embedded into
# lanzaboote. To make integrity verification fail, we actually have
# to modify the initrd. Appending crap to the end is a harmless way
# that would make the kernel still accept it.
mkModifiedInitrdTest = { name, useSecureBoot }: mkHashMismatchTest {
inherit name useSecureBoot;
appendCrapGlob = "/boot/EFI/nixos/initrd-*.efi";
};
mkModifiedKernelTest = { name, useSecureBoot }: mkHashMismatchTest {
inherit name useSecureBoot;
appendCrapGlob = "/boot/EFI/nixos/kernel-*.efi";
};
in
{
# TODO: user mode: OK
# TODO: how to get in: {deployed, audited} mode ?
basic = mkSecureBootTest {
name = "lanzaboote";
testScript = ''
machine.start()
assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
'';
};
systemd-initrd = mkSecureBootTest {
name = "lanzaboote-systemd-initrd";
machine = { ... }: {
boot.initrd.systemd.enable = true;
};
testScript = ''
machine.start()
assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
'';
};
# Test that a secret is appended to the initrd during installation. Smilar to
# the initrd-secrets test in Nixpkgs:
# https://github.com/NixOS/nixpkgs/blob/master/nixos/tests/initrd-secrets.nix
initrd-secrets =
let
secret = (pkgs.writeText "oh-so-secure" "uhh-ooh-uhh-security");
in
mkSecureBootTest {
name = "lanzaboote-initrd-secrets";
machine = { ... }: {
boot.initrd.secrets = {
"/test" = secret;
};
boot.initrd.postMountCommands = ''
cp /test /mnt-root/secret-from-initramfs
'';
};
testScript = ''
machine.start()
machine.wait_for_unit("multi-user.target")
machine.succeed("cmp ${secret} /secret-from-initramfs")
assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
'';
};
# Test that the secrets configured to be appended to the initrd get updated
# when installing a new generation even if the initrd itself (i.e. its store
# path) does not change.
#
# An unfortunate result of this NixOS feature is that updating the secrets
# without creating a new initrd might break previous generations. Verify that
# a new initrd (which is supposed to only differ by the secrets) is created
# in this case.
#
# This tests uses a specialisation to imitate a newer generation. This works
# because `lzbt` installs the specialisation of a generation AFTER installing
# the generation itself (thus making the specialisation "newer").
initrd-secrets-update =
let
originalSecret = (pkgs.writeText "oh-so-secure" "uhh-ooh-uhh-security");
newSecret = (pkgs.writeText "newly-secure" "so-much-better-now");
in
mkSecureBootTest {
name = "lanzaboote-initrd-secrets-update";
machine = { pkgs, lib, ... }: {
boot.initrd.secrets = {
"/test" = lib.mkDefault originalSecret;
};
boot.initrd.postMountCommands = ''
cp /test /mnt-root/secret-from-initramfs
'';
specialisation.variant.configuration = {
boot.initrd.secrets = {
"/test" = newSecret;
};
};
};
testScript = ''
machine.start()
machine.wait_for_unit("multi-user.target")
# Assert that only three boot files exists (a single kernel and a two
# initrds).
assert int(machine.succeed("ls -1 /boot/EFI/nixos | wc -l")) == 3
# It is expected that the initrd contains the original secret.
machine.succeed("cmp ${originalSecret} /secret-from-initramfs")
machine.succeed("bootctl set-default nixos-generation-1-specialisation-variant-\*.efi")
machine.succeed("sync")
machine.crash()
machine.start()
machine.wait_for_unit("multi-user.target")
# It is expected that the initrd of the specialisation contains the new secret.
machine.succeed("cmp ${newSecret} /secret-from-initramfs")
'';
};
modified-initrd-doesnt-boot-with-secure-boot = mkModifiedInitrdTest {
name = "modified-initrd-doesnt-boot-with-secure-boot";
useSecureBoot = true;
};
modified-initrd-boots-without-secure-boot = mkModifiedInitrdTest {
name = "modified-initrd-boots-without-secure-boot";
useSecureBoot = false;
};
modified-kernel-doesnt-boot-with-secure-boot = mkModifiedKernelTest {
name = "modified-kernel-doesnt-boot-with-secure-boot";
useSecureBoot = true;
};
modified-kernel-boots-without-secure-boot = mkModifiedKernelTest {
name = "modified-kernel-boots-without-secure-boot";
useSecureBoot = false;
};
specialisation-works = mkSecureBootTest {
name = "specialisation-still-boot-under-secureboot";
machine = { pkgs, ... }: {
specialisation.variant.configuration = {
environment.systemPackages = [
pkgs.efibootmgr
];
};
};
testScript = ''
machine.start()
print(machine.succeed("ls -lah /boot/EFI/Linux"))
# TODO: make it more reliable to find this filename, i.e. read it from somewhere?
machine.succeed("bootctl set-default nixos-generation-1-specialisation-variant-\*.efi")
machine.succeed("sync")
machine.fail("efibootmgr")
machine.crash()
machine.start()
print(machine.succeed("bootctl"))
# Only the specialisation contains the efibootmgr binary.
machine.succeed("efibootmgr")
'';
};
# We test if we can install Lanzaboote without Bootspec support.
synthesis = mkSecureBootTest {
name = "lanzaboote-synthesis";
machine = { lib, ... }: {
boot.bootspec.enable = lib.mkForce false;
};
testScript = ''
machine.start()
assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
'';
};
systemd-boot-loader-config = mkSecureBootTest {
name = "lanzaboote-systemd-boot-loader-config";
machine = {
boot.loader.timeout = 0;
boot.loader.systemd-boot.consoleMode = "auto";
};
testScript = ''
machine.start()
actual_loader_config = machine.succeed("cat /boot/loader/loader.conf").split("\n")
expected_loader_config = ["timeout 0", "console-mode auto"]
assert all(cfg in actual_loader_config for cfg in expected_loader_config), \
f"Expected: {expected_loader_config} is not included in actual config: '{actual_loader_config}'"
'';
};
export-efi-variables = mkSecureBootTest {
name = "lanzaboote-exports-efi-variables";
machine.environment.systemPackages = [ pkgs.efibootmgr ];
readEfiVariables = true;
testScript = ''
# We will choose to boot directly on the stub.
# To perform this trick, we will boot first with systemd-boot.
# Then, we will add a new boot entry in EFI with higher priority
# pointing to our stub.
# Finally, we will reboot.
# We will also assert that systemd-boot is not running
# by checking for the sd-boot's specific EFI variables.
machine.start()
# By construction, nixos-generation-1.efi is the stub we are interested in.
# TODO: this should work -- machine.succeed("efibootmgr -d /dev/vda -c -l \\EFI\\Linux\\nixos-generation-1.efi") -- efivars are not persisted
# across reboots atm?
# cheat code no 1
machine.succeed("cp /boot/EFI/Linux/nixos-generation-1-*.efi /boot/EFI/BOOT/BOOTX64.EFI")
machine.succeed("cp /boot/EFI/Linux/nixos-generation-1-*.efi /boot/EFI/systemd/systemd-bootx64.efi")
# Let's reboot.
machine.succeed("sync")
machine.crash()
machine.start()
# This is the sd-boot EFI variable indicator, we should not have it at this point.
print(machine.execute("bootctl")[1]) # Check if there's incorrect value in the output.
machine.succeed(
"test -e /sys/firmware/efi/efivars/LoaderEntrySelected-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f && false || true"
)
expected_variables = ["LoaderDevicePartUUID",
"LoaderImageIdentifier",
"LoaderFirmwareInfo",
"LoaderFirmwareType",
"StubInfo",
"StubFeatures"
]
# Debug all systemd loader specification GUID EFI variables loaded by the current environment.
print(machine.succeed(f"ls /sys/firmware/efi/efivars/*-{SD_LOADER_GUID}"))
with subtest("Check if supported variables are exported"):
for expected_var in expected_variables:
machine.succeed(f"test -e /sys/firmware/efi/efivars/{expected_var}-{SD_LOADER_GUID}")
with subtest("Is `StubInfo` correctly set"):
assert "lanzastub" in read_string_variable("StubInfo"), "Unexpected stub information, provenance is not lanzaboote project!"
assert_variable_string("LoaderImageIdentifier", "\\EFI\\BOOT\\BOOTX64.EFI")
# TODO: exploit QEMU test infrastructure to pass the good value all the time.
assert_variable_string("LoaderDevicePartUUID", "1c06f03b-704e-4657-b9cd-681a087a2fdc")
# OVMF tests are using EDK II tree.
assert_variable_string_contains("LoaderFirmwareInfo", "EDK II")
assert_variable_string_contains("LoaderFirmwareType", "UEFI")
with subtest("Is `StubFeatures` non-zero"):
assert struct.unpack('<Q', read_raw_variable("StubFeatures")) != 0
'';
};
tpm2-export-efi-variables = mkSecureBootTest {
name = "lanzaboote-tpm2-exports-efi-variables";
useTPM2 = true;
readEfiVariables = true;
testScript = ''
machine.start()
# TODO: the other variables are not yet supported.
expected_variables = [
"StubPcrKernelImage"
]
# Debug all systemd loader specification GUID EFI variables loaded by the current environment.
print(machine.succeed(f"ls /sys/firmware/efi/efivars/*-{SD_LOADER_GUID}"))
with subtest("Check if supported variables are exported"):
for expected_var in expected_variables:
machine.succeed(f"test -e /sys/firmware/efi/efivars/{expected_var}-{SD_LOADER_GUID}")
# "Static" parts of the UKI is measured in PCR11
assert_variable_uint("StubPcrKernelImage", 11)
'';
};
}