nixos-config/modules/systemd-secure-boot/systemd-boot-builder.py

300 lines
12 KiB
Python

#! @python3@/bin/python3 -B
import argparse
import shutil
import os
import sys
import errno
import subprocess
import glob
import tempfile
import errno
import warnings
import ctypes
libc = ctypes.CDLL("libc.so.6")
import re
import datetime
import glob
import os.path
from typing import Tuple, List, Optional, Callable
def install_signed_if_required(source: Callable[[], str], dest: str) -> None:
if "@secureBootEnable@" == "1":
try:
subprocess.check_call(
["@sbsigntool@/bin/sbverify", "--cert=@certPath@", dest],
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL)
except subprocess.CalledProcessError:
subprocess.check_call([
"@sbsigntool@/bin/sbsign",
"--key=@keyPath@",
"--cert=@certPath@",
"--output=%s.tmp" % (dest),
source()],
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL)
os.rename("%s.tmp" % (dest), dest)
elif not os.path.exists(dest):
shutil.copy(source(), dest)
def efi_section(name: str, path: str, vma: str) -> List[str]:
return [
"--add-section",
".%s=%s" % (name, path),
"--change-section-vma",
".%s=%s" % (name, vma)]
def system_dir(profile: Optional[str], generation: int) -> str:
if profile:
return "/nix/var/nix/profiles/system-profiles/%s-%d-link" % (profile, generation)
else:
return "/nix/var/nix/profiles/system-%d-link" % (generation)
# The boot loader entry for memtest86.
#
# TODO: This is hard-coded to use the 64-bit EFI app, but it could probably
# be updated to use the 32-bit EFI app on 32-bit systems. The 32-bit EFI
# app filename is BOOTIA32.efi.
MEMTEST_BOOT_ENTRY = """title MemTest86
efi /efi/memtest86/BOOTX64.efi
"""
def write_loader_conf(profile: Optional[str], generation: int) -> None:
with open("@efiSysMountPoint@/loader/loader.conf.tmp", 'w') as f:
if "@timeout@" != "":
f.write("timeout @timeout@\n")
if profile:
f.write("default nixos-%s-generation-%d.efi\n" % (profile, generation))
else:
f.write("default nixos-generation-%d.efi\n" % (generation))
if not @editor@:
f.write("editor 0\n");
f.write("console-mode @consoleMode@\n");
os.rename("@efiSysMountPoint@/loader/loader.conf.tmp", "@efiSysMountPoint@/loader/loader.conf")
def profile_path(profile: Optional[str], generation: int, name: str) -> str:
return os.path.realpath("%s/%s" % (system_dir(profile, generation), name))
def path_from_profile(profile: Optional[str], generation: int, name: str) -> str:
store_file_path = profile_path(profile, generation, name)
suffix = os.path.basename(store_file_path)
store_dir = os.path.basename(os.path.dirname(store_file_path))
efi_file_path = "/efi/nixos/%s-%s.efi" % (store_dir, suffix)
return efi_file_path
def describe_generation(generation_dir: str) -> str:
try:
with open("%s/nixos-version" % generation_dir) as f:
nixos_version = f.read()
except IOError:
nixos_version = "Unknown"
kernel_dir = os.path.dirname(os.path.realpath("%s/kernel" % generation_dir))
module_dir = glob.glob("%s/lib/modules/*" % kernel_dir)[0]
kernel_version = os.path.basename(module_dir)
build_time = int(os.path.getctime(generation_dir))
build_date = datetime.datetime.fromtimestamp(build_time).strftime('%F')
description = "NixOS {}, Linux Kernel {}, Built on {}".format(
nixos_version, kernel_version, build_date
)
return description
def write_entry(profile: Optional[str], generation: int) -> None:
if profile:
entry_file = "@efiSysMountPoint@/EFI/Linux/nixos-%s-generation-%d.efi" % (profile, generation)
else:
entry_file = "@efiSysMountPoint@/EFI/Linux/nixos-generation-%d.efi" % (generation)
with tempfile.TemporaryDirectory() as tmpdir:
def make_unified_kernel() -> str:
kernel = profile_path(profile, generation, "kernel")
initrd = profile_path(profile, generation, "initrd")
osrel = profile_path(profile, generation, "etc/os-release")
cmdline = "%s/cmdline" % (tmpdir)
efistub = profile_path(profile, generation, "sw/lib/systemd/boot/efi/linuxx64.efi.stub")
if not os.path.exists(efistub):
efistub = "@systemd@lib/systemd/boot/efi/linuxx64.efi.stub"
try:
append_initrd_secrets = profile_path(profile, generation, "append-initrd-secrets")
subprocess.check_call([append_initrd_secrets, initrd])
except FileNotFoundError:
pass
generation_dir = os.readlink(system_dir(profile, generation))
kernel_params = "init=%s/init " % generation_dir
with open("%s/kernel-params" % (generation_dir)) as params_file:
kernel_params = kernel_params + params_file.read()
with open(cmdline, 'w') as f:
f.write(kernel_params)
subprocess.check_call([
"@binutils@/bin/objcopy",
*efi_section("osrel", osrel, "0x20000"),
*efi_section("cmdline", cmdline, "0x30000"),
*efi_section("linux", kernel, "0x40000"),
*efi_section("initrd", initrd, "0x3000000"),
efistub,
"%s/unified.efi" % (tmpdir)])
return "%s/unified.efi" % (tmpdir)
install_signed_if_required(make_unified_kernel, entry_file)
def mkdir_p(path: str) -> None:
try:
os.makedirs(path)
except OSError as e:
if e.errno != errno.EEXIST or not os.path.isdir(path):
raise
def get_generations(profile: Optional[str] = None) -> List[Tuple[Optional[str], int]]:
gen_list = subprocess.check_output([
"@nix@/bin/nix-env",
"--list-generations",
"-p",
"/nix/var/nix/profiles/%s" % ("system-profiles/" + profile if profile else "system"),
"--option", "build-users-group", ""],
universal_newlines=True)
gen_lines = gen_list.split('\n')
gen_lines.pop()
configurationLimit = @configurationLimit@
return [ (profile, int(line.split()[0])) for line in gen_lines ][-configurationLimit:]
def remove_old_entries(gens: List[Tuple[Optional[str], int]]) -> None:
rex_profile = re.compile("^@efiSysMountPoint@/EFI/Linux/nixos-(.*)-generation-.*\.efi$")
rex_generation = re.compile("^@efiSysMountPoint@/EFI/Linux/nixos.*-generation-(.*)\.efi$")
known_paths = []
for gen in gens:
known_paths.append(path_from_profile(*gen, "kernel"))
known_paths.append(path_from_profile(*gen, "initrd"))
for path in glob.iglob("@efiSysMountPoint@/EFI/Linux/nixos*-generation-[1-9]*.efi"):
try:
if rex_profile.match(path):
prof = rex_profile.sub(r"\1", path)
else:
prof = "system"
gen_number = int(rex_generation.sub(r"\1", path))
if not (prof, gen_number) in gens:
os.unlink(path)
except ValueError:
pass
for path in glob.iglob("@efiSysMountPoint@/EFI/Linux/*"):
if not path in known_paths and not os.path.isdir(path):
os.unlink(path)
def get_profiles() -> List[str]:
if os.path.isdir("/nix/var/nix/profiles/system-profiles/"):
return [x
for x in os.listdir("/nix/var/nix/profiles/system-profiles/")
if not x.endswith("-link")]
else:
return []
def main() -> None:
parser = argparse.ArgumentParser(description='Update NixOS-related systemd-boot files')
parser.add_argument('default_config', metavar='DEFAULT-CONFIG', help='The default NixOS config to boot')
args = parser.parse_args()
try:
with open("/etc/machine-id") as machine_file:
machine_id = machine_file.readlines()[0]
except IOError as e:
if e.errno != errno.ENOENT:
raise
# Since systemd version 232 a machine ID is required and it might not
# be there on newly installed systems, so let's generate one so that
# bootctl can find it and we can also pass it to write_entry() later.
cmd = ["@systemd@/bin/systemd-machine-id-setup", "--print"]
machine_id = subprocess.run(
cmd, text=True, check=True, stdout=subprocess.PIPE
).stdout.rstrip()
if os.getenv("NIXOS_INSTALL_GRUB") == "1":
warnings.warn("NIXOS_INSTALL_GRUB env var deprecated, use NIXOS_INSTALL_BOOTLOADER", DeprecationWarning)
os.environ["NIXOS_INSTALL_BOOTLOADER"] = "1"
if os.getenv("NIXOS_INSTALL_BOOTLOADER") == "1":
# bootctl uses fopen() with modes "wxe" and fails if the file exists.
if os.path.exists("@efiSysMountPoint@/loader/loader.conf"):
os.unlink("@efiSysMountPoint@/loader/loader.conf")
if "@canTouchEfiVariables@" == "1":
subprocess.check_call(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "install"])
else:
subprocess.check_call(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "--no-variables", "install"])
else:
# Update bootloader to latest if needed
systemd_version = subprocess.check_output(["@systemd@/bin/bootctl", "--version"], universal_newlines=True).split()[1]
sdboot_status = subprocess.check_output(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "status"], universal_newlines=True)
# See status_binaries() in systemd bootctl.c for code which generates this
m = re.search("^\W+File:.*/EFI/(BOOT|systemd)/.*\.efi \(systemd-boot ([\d.]+[^)]*)\)$",
sdboot_status, re.IGNORECASE | re.MULTILINE)
if m is None:
print("could not find any previously installed systemd-boot")
else:
sdboot_version = m.group(2)
if systemd_version > sdboot_version:
print("updating systemd-boot from %s to %s" % (sdboot_version, systemd_version))
subprocess.check_call(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "update"])
install_signed_if_required(lambda: "@systemd@/lib/systemd/boot/efi/systemd-bootx64.efi", "@efiSysMountPoint@/EFI/BOOT/BOOTX64.efi")
install_signed_if_required(lambda: "@systemd@/lib/systemd/boot/efi/systemd-bootx64.efi", "@efiSysMountPoint@/EFI/systemd/systemd-bootx64.efi")
mkdir_p("@efiSysMountPoint@/EFI/Linux")
mkdir_p("@efiSysMountPoint@/loader/entries")
gens = get_generations()
for profile in get_profiles():
gens += get_generations(profile)
remove_old_entries(gens)
for gen in gens:
try:
write_entry(*gen)
if os.readlink(system_dir(*gen)) == args.default_config:
write_loader_conf(*gen)
except OSError as e:
print("ignoring profile '{}' in the list of boot entries because of the following error:\n{}".format(profile, e), file=sys.stderr)
memtest_entry_file = "@efiSysMountPoint@/loader/entries/memtest86.conf"
if os.path.exists(memtest_entry_file):
os.unlink(memtest_entry_file)
shutil.rmtree("@efiSysMountPoint@/efi/memtest86", ignore_errors=True)
if "@memtest86@" != "":
mkdir_p("@efiSysMountPoint@/efi/memtest86")
for path in glob.iglob("@memtest86@/*"):
if os.path.isdir(path):
shutil.copytree(path, os.path.join("@efiSysMountPoint@/efi/memtest86", os.path.basename(path)))
else:
shutil.copy(path, "@efiSysMountPoint@/efi/memtest86/")
memtest_entry_file = "@efiSysMountPoint@/loader/entries/memtest86.conf"
memtest_entry_file_tmp_path = "%s.tmp" % memtest_entry_file
with open(memtest_entry_file_tmp_path, 'w') as f:
f.write(MEMTEST_BOOT_ENTRY)
os.rename(memtest_entry_file_tmp_path, memtest_entry_file)
# Since fat32 provides little recovery facilities after a crash,
# it can leave the system in an unbootable state, when a crash/outage
# happens shortly after an update. To decrease the likelihood of this
# event sync the efi filesystem after each update.
rc = libc.syncfs(os.open("@efiSysMountPoint@", os.O_RDONLY))
if rc != 0:
print("could not sync @efiSysMountPoint@: {}".format(os.strerror(rc)), file=sys.stderr)
if __name__ == '__main__':
main()