FreedomBox/plinth/modules/letsencrypt/privileged.py

# SPDX-License-Identifier: AGPL-3.0-or-later
"""Configure Let's Encrypt."""

import filecmp
import importlib
import inspect
import os
import pathlib
import re
import shutil
import sys
from typing import Any

from plinth import action_utils
from plinth import app as app_module
from plinth import module_loader
from plinth.actions import privileged
from plinth.modules import letsencrypt as le

TEST_MODE = False
LE_DIRECTORY = '/etc/letsencrypt/'
ETC_SSL_DIRECTORY = '/etc/ssl/'
AUTHENTICATOR = 'webroot'
WEB_ROOT_PATH = '/var/www/html'


def _get_certificate_expiry(domain: str) -> str:
    """Return the expiry date of a certificate."""
    certificate_file = os.path.join(le.LIVE_DIRECTORY, domain, 'cert.pem')
    output = action_utils.run(
        ['openssl', 'x509', '-enddate', '-noout', '-in', certificate_file],
        check=True).stdout
    return output.decode().strip().split('=')[1]


def _get_modified_time(domain: str) -> int:
    """Return the last modified time of a certificate."""
    certificate_file = pathlib.Path(le.LIVE_DIRECTORY) / domain / 'cert.pem'
    return int(certificate_file.stat().st_mtime)


def _get_validity_status(domain: str) -> str:
    """Return validity status of a certificate; valid, revoked, expired."""
    output = action_utils.run(['certbot', 'certificates', '-d', domain],
                              check=True).stdout
    line = output.decode(sys.stdout.encoding)

    match = re.search(r'INVALID: (.*)\)', line)
    if match is not None:
        validity = match.group(1).lower()
    elif re.search('VALID', line) is not None:
        validity = 'valid'
    else:
        validity = 'unknown'

    return validity


def _get_status() -> dict[str, Any]:
    """Return Python dictionary of currently configured domains.

    Should be run as root, otherwise might yield a wrong, empty answer.
    """
    try:
        domains = os.listdir(le.LIVE_DIRECTORY)
    except OSError:
        domains = []

    domains = [
        domain for domain in domains
        if os.path.isdir(os.path.join(le.LIVE_DIRECTORY, domain))
    ]

    domain_status = {}
    for domain in domains:
        domain_status[domain] = {
            'certificate_available':
                True,
            'expiry_date':
                _get_certificate_expiry(domain),
            'web_enabled':
                action_utils.webserver_is_enabled(domain, kind='site'),
            'validity':
                _get_validity_status(domain),
            'lineage':
                str(pathlib.Path(le.LIVE_DIRECTORY) / domain),
            'modified_time':
                _get_modified_time(domain)
        }
    return domain_status


@privileged
def get_status() -> dict[str, dict]:
    """Return a dictionary of currently configured domains."""
    domain_status = _get_status()
    return {'domains': domain_status}


@privileged
def get_modified_time(domain: str) -> int:
    """Return the modified time of a certificate as integer."""
    return _get_modified_time(domain)


@privileged
def revoke(domain: str):
    """Disable a domain and revoke the certificate."""
    cert_path = pathlib.Path(le.LIVE_DIRECTORY) / domain / 'cert.pem'
    if cert_path.exists():
        command = [
            'certbot', 'revoke', '--non-interactive', '--domain', domain,
            '--cert-path',
            str(cert_path)
        ]
        if TEST_MODE:
            command.append('--staging')

        action_utils.run(command, check=True)

    action_utils.webserver_disable(domain, kind='site')


@privileged
def obtain(domain: str):
    """Obtain a certificate for a domain and setup website."""
    command = [
        'certbot', 'certonly', '--non-interactive', '--text', '--agree-tos',
        '--register-unsafely-without-email', '--domain', domain,
        '--authenticator', AUTHENTICATOR, '--webroot-path', WEB_ROOT_PATH,
        '--renew-by-default'
    ]
    if TEST_MODE:
        command.append('--staging')

    action_utils.run(command, check=True)


@privileged
def copy_certificate(managing_app: str, source_private_key: str,
                     source_certificate: str, private_key: str,
                     certificate: str, user_owner: str, group_owner: str):
    """Copy certificate from LE directory to daemon's directory.

    Set ownership and permissions as requested needed by the daemon.

    """
    source_private_key_path = pathlib.Path(source_private_key).resolve()
    _assert_source_directory(source_private_key_path)
    source_certificate_path = pathlib.Path(source_certificate).resolve()
    _assert_source_directory(source_certificate_path)

    private_key_path = pathlib.Path(private_key).resolve()
    _assert_managed_path(managing_app, private_key_path)
    certificate_path = pathlib.Path(certificate).resolve()
    _assert_managed_path(managing_app, certificate_path)

    # Create directories, owned by root
    private_key_path.parent.mkdir(mode=0o755, parents=True, exist_ok=True)
    certificate_path.parent.mkdir(mode=0o755, parents=True, exist_ok=True)

    # Private key is only accessible to the user owner
    with action_utils.umask(0o177):
        shutil.copyfile(source_private_key_path, private_key_path)

        if certificate_path != private_key_path:
            # Certificate is only writable by the user owner
            with action_utils.umask(0o133):
                shutil.copyfile(source_certificate_path, certificate_path)
        else:
            # If private key and certificate are the same file, append one
            # after the other.
            source_certificate_bytes = source_certificate_path.read_bytes()
            with private_key_path.open(mode='a+b') as file_handle:
                file_handle.write(source_certificate_bytes)

    shutil.chown(certificate_path, user=user_owner, group=group_owner)
    shutil.chown(private_key_path, user=user_owner, group=group_owner)


@privileged
def compare_certificate(managing_app: str, source_private_key: str,
                        source_certificate: str, private_key: str,
                        certificate: str) -> bool:
    """Compare LE certificate with an app certificate."""
    source_private_key_path = pathlib.Path(source_private_key)
    source_certificate_path = pathlib.Path(source_certificate)
    _assert_source_directory(source_private_key_path)
    _assert_source_directory(source_certificate_path)

    private_key_path = pathlib.Path(private_key)
    certificate_path = pathlib.Path(certificate)
    _assert_managed_path(managing_app, private_key_path)
    _assert_managed_path(managing_app, certificate_path)

    result = False
    try:
        if filecmp.cmp(source_certificate_path, certificate_path) and \
           filecmp.cmp(source_private_key_path, private_key_path):
            result = True
    except FileNotFoundError:
        result = False

    return result


def _assert_source_directory(path):
    """Assert that a path is a valid source of a certificates."""
    assert (str(path).startswith(LE_DIRECTORY)
            or str(path).startswith(ETC_SSL_DIRECTORY))


def _get_managed_path(path):
    """Return the managed path given a certificate path."""
    if '{domain}' in path:
        return pathlib.Path(path.partition('{domain}')[0])

    return pathlib.Path(path).parent


def _assert_managed_path(module, path):
    """Check that path is in fact managed by module."""
    module_path = module_loader.get_module_import_path(module)
    module = importlib.import_module(module_path)
    module_classes = inspect.getmembers(module, inspect.isclass)
    app_classes = [
        cls[1] for cls in module_classes if issubclass(cls[1], app_module.App)
    ]

    managed_paths = []
    for cls in app_classes:
        app = cls()
        from plinth.modules.letsencrypt.components import LetsEncrypt
        components = app.get_components_of_type(LetsEncrypt)
        for component in components:
            if component.private_key_path:
                managed_paths.append(
                    _get_managed_path(component.private_key_path))
            if component.certificate_path:
                managed_paths.append(
                    _get_managed_path(component.certificate_path))

    if not set(path.parents).intersection(set(managed_paths)):
        raise AssertionError('Not a managed path')


@privileged
def delete(domain: str):
    """Disable a domain and delete the certificate."""
    command = ['certbot', 'delete', '--non-interactive', '--cert-name', domain]
    action_utils.run(command, check=True)
    action_utils.webserver_disable(domain, kind='site')