certbot/certbot-apache/certbot_apache/_internal/override_centos.py

""" Distribution specific override class for CentOS family (RHEL, Fedora) """
import logging
from typing import cast
from typing import List

import zope.interface

from certbot import errors
from certbot import interfaces
from certbot import util
from certbot.errors import MisconfigurationError
from certbot_apache._internal import apache_util
from certbot_apache._internal import configurator
from certbot_apache._internal import parser

logger = logging.getLogger(__name__)


@zope.interface.provider(interfaces.IPluginFactory)
class CentOSConfigurator(configurator.ApacheConfigurator):
    """CentOS specific ApacheConfigurator override class"""

    OS_DEFAULTS = dict(
        server_root="/etc/httpd",
        vhost_root="/etc/httpd/conf.d",
        vhost_files="*.conf",
        logs_root="/var/log/httpd",
        ctl="apachectl",
        version_cmd=['apachectl', '-v'],
        restart_cmd=['apachectl', 'graceful'],
        restart_cmd_alt=['apachectl', 'restart'],
        conftest_cmd=['apachectl', 'configtest'],
        enmod=None,
        dismod=None,
        le_vhost_ext="-le-ssl.conf",
        handle_modules=False,
        handle_sites=False,
        challenge_location="/etc/httpd/conf.d",
        bin=None,
    )

    def config_test(self):
        """
        Override config_test to mitigate configtest error in vanilla installation
        of mod_ssl in Fedora. The error is caused by non-existent self-signed
        certificates referenced by the configuration, that would be autogenerated
        during the first (re)start of httpd.
        """

        os_info = util.get_os_info()
        fedora = os_info[0].lower() == "fedora"

        try:
            super(CentOSConfigurator, self).config_test()
        except errors.MisconfigurationError:
            if fedora:
                self._try_restart_fedora()
            else:
                raise

    def _try_restart_fedora(self):
        """
        Tries to restart httpd using systemctl to generate the self signed keypair.
        """

        try:
            util.run_script(['systemctl', 'restart', 'httpd'])
        except errors.SubprocessError as err:
            raise errors.MisconfigurationError(str(err))

        # Finish with actual config check to see if systemctl restart helped
        super(CentOSConfigurator, self).config_test()

    def _prepare_options(self):
        """
        Override the options dictionary initialization in order to support
        alternative restart cmd used in CentOS.
        """
        super(CentOSConfigurator, self)._prepare_options()
        cast(List[str], self.options["restart_cmd_alt"])[0] = self.option("ctl")

    def get_parser(self):
        """Initializes the ApacheParser"""
        return CentOSParser(
            self.option("server_root"), self.option("vhost_root"),
            self.version, configurator=self)

    def _deploy_cert(self, *args, **kwargs):  # pylint: disable=arguments-differ
        """
        Override _deploy_cert in order to ensure that the Apache configuration
        has "LoadModule ssl_module..." before parsing the VirtualHost configuration
        that was created by Certbot
        """
        super(CentOSConfigurator, self)._deploy_cert(*args, **kwargs)
        if self.version < (2, 4, 0):
            self._deploy_loadmodule_ssl_if_needed()

    def _deploy_loadmodule_ssl_if_needed(self):
        """
        Add "LoadModule ssl_module <pre-existing path>" to main httpd.conf if
        it doesn't exist there already.
        """

        loadmods = self.parser.find_dir("LoadModule", "ssl_module", exclude=False)

        correct_ifmods: List[str] = []
        loadmod_args: List[str] = []
        loadmod_paths: List[str] = []
        for m in loadmods:
            noarg_path = m.rpartition("/")[0]
            path_args = self.parser.get_all_args(noarg_path)
            if loadmod_args:
                if loadmod_args != path_args:
                    msg = ("Certbot encountered multiple LoadModule directives "
                           "for LoadModule ssl_module with differing library paths. "
                           "Please remove or comment out the one(s) that are not in "
                           "use, and run Certbot again.")
                    raise MisconfigurationError(msg)
            else:
                loadmod_args = path_args

            centos_parser: CentOSParser = cast(CentOSParser, self.parser)
            if centos_parser.not_modssl_ifmodule(noarg_path):
                if centos_parser.loc["default"] in noarg_path:
                    # LoadModule already in the main configuration file
                    if ("ifmodule/" in noarg_path.lower() or
                        "ifmodule[1]" in noarg_path.lower()):
                        # It's the first or only IfModule in the file
                        return
                # Populate the list of known !mod_ssl.c IfModules
                nodir_path = noarg_path.rpartition("/directive")[0]
                correct_ifmods.append(nodir_path)
            else:
                loadmod_paths.append(noarg_path)

        if not loadmod_args:
            # Do not try to enable mod_ssl
            return

        # Force creation as the directive wasn't found from the beginning of
        # httpd.conf
        rootconf_ifmod = self.parser.create_ifmod(
            parser.get_aug_path(self.parser.loc["default"]),
            "!mod_ssl.c", beginning=True)
        # parser.get_ifmod returns a path postfixed with "/", remove that
        self.parser.add_dir(rootconf_ifmod[:-1], "LoadModule", loadmod_args)
        correct_ifmods.append(rootconf_ifmod[:-1])
        self.save_notes += "Added LoadModule ssl_module to main configuration.\n"

        # Wrap LoadModule mod_ssl inside of <IfModule !mod_ssl.c> if it's not
        # configured like this already.
        for loadmod_path in loadmod_paths:
            nodir_path = loadmod_path.split("/directive")[0]
            # Remove the old LoadModule directive
            self.parser.aug.remove(loadmod_path)

            # Create a new IfModule !mod_ssl.c if not already found on path
            ssl_ifmod = self.parser.get_ifmod(nodir_path, "!mod_ssl.c",
                                            beginning=True)[:-1]
            if ssl_ifmod not in correct_ifmods:
                self.parser.add_dir(ssl_ifmod, "LoadModule", loadmod_args)
                correct_ifmods.append(ssl_ifmod)
                self.save_notes += ("Wrapped pre-existing LoadModule ssl_module "
                                    "inside of <IfModule !mod_ssl> block.\n")


class CentOSParser(parser.ApacheParser):
    """CentOS specific ApacheParser override class"""
    def __init__(self, *args, **kwargs):
        # CentOS specific configuration file for Apache
        self.sysconfig_filep = "/etc/sysconfig/httpd"
        super(CentOSParser, self).__init__(*args, **kwargs)

    def update_runtime_variables(self):
        """ Override for update_runtime_variables for custom parsing """
        # Opportunistic, works if SELinux not enforced
        super(CentOSParser, self).update_runtime_variables()
        self.parse_sysconfig_var()

    def parse_sysconfig_var(self):
        """ Parses Apache CLI options from CentOS configuration file """
        defines = apache_util.parse_define_file(self.sysconfig_filep, "OPTIONS")
        for k in defines:
            self.variables[k] = defines[k]

    def not_modssl_ifmodule(self, path):
        """Checks if the provided Augeas path has argument !mod_ssl"""

        if "ifmodule" not in path.lower():
            return False

        # Trim the path to the last ifmodule
        workpath = path.lower()
        while workpath:
            # Get path to the last IfModule (ignore the tail)
            parts = workpath.rpartition("ifmodule")

            if not parts[0]:
                # IfModule not found
                break
            ifmod_path = parts[0] + parts[1]
            # Check if ifmodule had an index
            if parts[2].startswith("["):
                # Append the index from tail
                ifmod_path += parts[2].partition("/")[0]
            # Get the original path trimmed to correct length
            # This is required to preserve cases
            ifmod_real_path = path[0:len(ifmod_path)]
            if "!mod_ssl.c" in self.get_all_args(ifmod_real_path):
                return True
            # Set the workpath to the heading part
            workpath = parts[0]

        return False