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#!/usr/bin/python3
import argparse
import glob
import os
import subprocess
import sys
import tempfile
import yaml
verbose = False
def log(msg):
if verbose:
sys.stderr.write(msg)
sys.stderr.write("\n")
sys.stderr.flush()
class Config:
defaults = {
"authorized_keys_file": None,
"host_cert_file": None,
"host_key_file": None,
"host_cert_cmd": None,
"host_key_cmd": None,
"user_ca_pub_file": None,
"user_ca_pub_cmd": None,
"cmd_as_user": None,
"wifi_name": None,
"wifi_password": None,
}
exandable = [
"authorized_keys_file",
"host_cert_file",
"host_key_file",
"user_ca_pub_file",
]
def __init__(self):
self.config = dict(self.defaults)
def __getitem__(self, key):
return self.config[key]
def read(self, filename):
log(f"reading configuration from {filename}")
with open(filename) as f:
obj = yaml.safe_load(f)
if obj is not None:
self.config.update(obj)
for key in self.exandable:
if self.config[key] is not None:
self.config[key] = os.path.expanduser(self.config[key])
log(f"config:")
for key in self.config:
log(f" {key}={self.config[key]!r}")
def user_ca_pub(self):
return self._get_from_file_or_cmd("user_ca_pub", "user CA public key", None)
def host_key(self, hostname):
return self._get_from_file_or_cmd("host_key", "host private key", hostname)
def host_cert(self, hostname):
return self._get_from_file_or_cmd("host_cert", "host certificate", hostname)
def wifi(self):
return self.config.get("wifi_name"), self.config.get("wifi_password")
def _get_from_file_or_cmd(self, prefix, msg, hostname):
filename = self.config.get(f"{prefix}_file")
if filename is not None:
log(f"reading {msg} from {filename}")
return cat(filename)
cmd = self.config.get(f"{prefix}_cmd")
if cmd is None:
return None
if hostname is not None:
cmd = hostname.join(cmd.split("$HOST"))
if cmd is not None:
user = self.config.get("cmd_as_user")
if user is not None:
log(f"reading {msg} from command (as {user}): {cmd}")
return run(cmd, user=user)
else:
log(f"reading {msg} from command: {cmd}")
return run(cmd)
log(f"can't read {msg}")
return None
def mount(drive, mp):
log(f"mounting {drive} on {mp}")
subprocess.run(["mount", drive, mp])
def unmount(path):
log(f"un-mounting {path}")
subprocess.run(["umount", path])
def run(cmd, user=None):
if user is not None:
argv = ["sudo", "-u", user, "--", "/bin/bash", "-c", cmd]
log(f"argv: {argv}")
p = subprocess.run(argv, capture_output=True)
else:
p = subprocess.run(cmd, shell=True, capture_output=True)
if p.returncode != 0:
sys.stderr.write(p.stderr.decode())
sys.exit(1)
return p.stdout.decode()
def cat(path):
log(f"reading {path}")
with open(path) as f:
return f.read()
def write(path, content, owner, group, mode):
log(f"writing {path}")
with open(path, "w") as f:
f.write(content)
os.chown(path, owner, group)
os.chmod(path, mode)
def dir_exists(mp, path):
full = os.path.join(mp, path)
if not os.path.exists(full):
raise Exception(f"{full} does not exist")
def host_id(config, mp, installer_hostname):
key = config.host_key(installer_hostname)
cert = config.host_cert(installer_hostname)
if key is None or cert is None:
return
config_d = "/etc/ssh/sshd_config.d"
host_key = "/etc/ssh/ssh_host_key"
host_cert = "/etc/ssh/ssh_host_key-cert.pub"
# Remove all existing host keys.
for filename in glob.glob(f"{mp}/etc/ssh/ssh_host_*_key*"):
os.remove(filename)
# Note that the order of HostKey and HostCertificate lines matter.
write(
f"{mp}{config_d}/id.conf",
f"""
HostKeyAlgorithms ssh-ed25519,ssh-ed25519-cert-v01@openssh.com
HostKey {host_key}
HostCertificate {host_cert}
""",
0,
0,
0o644,
)
write(f"{mp}{host_key}", key, 0, 0, 0o600)
write(f"{mp}{host_cert}", cert, 0, 0, 0o644)
def authorized_keys(config, mp):
authz_keys_path = config["authorized_keys_file"]
if authz_keys_path is None:
return
authz_keys = cat(authz_keys_path)
write(f"{mp}/root/.ssh/authorized_keys", authz_keys, 0, 0, 0x600)
def user_ca(config, mp):
ca_key = config.user_ca_pub()
if ca_key is None:
return
include = f"{mp}/etc/ssh/sshd_config.d/user_ca.conf"
write(include, "TrustedUserCAKeys /etc/ssh/user_ca_pubs\n", 0, 0, 0o644)
cakeys = f"{mp}/etc/ssh/user_ca_pubs"
write(cakeys, ca_key, 0, 0, 0o644)
def wifi(config, mp):
(name, password) = config.wifi()
if name and password:
data = f"[Security]\nPassphrase={password}\n"
filename = f"{mp}/var/lib/iwd/{name}.psk"
dirname = os.path.dirname(filename)
os.makedirs(dirname, exist_ok=True)
write(filename, data, 0, 0, 0o600)
def main():
log("configure-image starting")
p = argparse.ArgumentParser()
p.add_argument("--verbose", action="store_true", help="be verbose")
p.add_argument("--hostname", default="v-i", help="host name of installer image")
p.add_argument("config", metavar="FILE", help="configuration file")
p.add_argument(
"drive",
metavar="DEVICE",
help="device file of the drive with v-i installer image",
)
args = p.parse_args()
global verbose
verbose = args.verbose
config = Config()
config.read(args.config)
mp = tempfile.mkdtemp()
drive1 = f"{args.drive}1"
drive2 = f"{args.drive}2"
mount(drive2, mp)
try:
dir_exists(mp, "etc/ssh")
host_id(config, mp, args.hostname)
authorized_keys(config, mp)
user_ca(config, mp)
wifi(config, mp)
finally:
unmount(mp)
os.rmdir(mp)
log("all good")
main()
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