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nixpkgs/nixos/tests/systemd-credentials-tpm2.nix
Tobias Markus e83babd493 nixos/tests/systemd-credentials-tpm2: Add tests for systemd credentials
Add a test that checks whether systemd can access the TPM in order
access credentials requested via Load/SetCredentialEncrypted.
2023-02-20 13:54:49 +01:00

125 lines
4 KiB
Nix

import ./make-test-python.nix ({ lib, pkgs, system, ... }:
let
tpmSocketPath = "/tmp/swtpm-sock";
tpmDeviceModels = {
x86_64-linux = "tpm-tis";
aarch64-linux = "tpm-tis-device";
};
in
{
name = "systemd-credentials-tpm2";
meta = {
maintainers = with pkgs.lib.maintainers; [ tmarkus ];
};
nodes.machine = { pkgs, ... }: {
virtualisation = {
qemu.options = [
"-chardev socket,id=chrtpm,path=${tpmSocketPath}"
"-tpmdev emulator,id=tpm_dev_0,chardev=chrtpm"
"-device ${tpmDeviceModels.${system}},tpmdev=tpm_dev_0"
];
};
boot.initrd.availableKernelModules = [ "tpm_tis" ];
environment.systemPackages = with pkgs; [ diffutils ];
};
testScript = ''
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")
CRED_NAME = "testkey"
CRED_RAW_FILE = f"/root/{CRED_NAME}"
CRED_FILE = f"/root/{CRED_NAME}.cred"
def systemd_run(machine, cmd):
machine.log(f"Executing command (via systemd-run): \"{cmd}\"")
(status, out) = machine.execute( " ".join([
"systemd-run",
"--service-type=exec",
"--quiet",
"--wait",
"-E PATH=\"$PATH\"",
"-p StandardOutput=journal",
"-p StandardError=journal",
f"-p LoadCredentialEncrypted={CRED_NAME}:{CRED_FILE}",
f"$SHELL -c '{cmd}'"
]) )
if status != 0:
raise Exception(f"systemd_run failed (status {status})")
machine.log("systemd-run finished successfully")
tpm = Tpm()
@polling_condition
def swtpm_running():
tpm.check()
machine.wait_for_unit("multi-user.target")
with subtest("Check whether TPM device exists"):
machine.succeed("test -e /dev/tpm0")
machine.succeed("test -e /dev/tpmrm0")
with subtest("Check whether systemd-creds detects TPM2 correctly"):
cmd = "systemd-creds has-tpm2"
machine.log(f"Running \"{cmd}\"")
(status, _) = machine.execute(cmd)
# Check exit code equals 0 or 1 (1 means firmware support is missing, which is OK here)
if status != 0 and status != 1:
raise Exception("systemd-creds failed to detect TPM2")
with subtest("Encrypt credential using systemd-creds"):
machine.succeed(f"dd if=/dev/urandom of={CRED_RAW_FILE} bs=1k count=16")
machine.succeed(f"systemd-creds --with-key=host+tpm2 encrypt --name=testkey {CRED_RAW_FILE} {CRED_FILE}")
with subtest("Write provided credential and check for equality"):
CRED_OUT_FILE = f"/root/{CRED_NAME}.out"
systemd_run(machine, f"systemd-creds cat testkey > {CRED_OUT_FILE}")
machine.succeed(f"cmp --silent -- {CRED_RAW_FILE} {CRED_OUT_FILE}")
with subtest("Check whether systemd service can see credential in systemd-creds list"):
systemd_run(machine, f"systemd-creds list | grep {CRED_NAME}")
with subtest("Check whether systemd service can access credential in $CREDENTIALS_DIRECTORY"):
systemd_run(machine, f"cmp --silent -- $CREDENTIALS_DIRECTORY/{CRED_NAME} {CRED_RAW_FILE}")
'';
})