tails-additional-software

#!/usr/bin/env python3

import gettext
import json
import logging
import logging.handlers
import os
import os.path
import pwd
import shutil
import subprocess
import sys

import apt.cache

from tailslib import LIVE_USERNAME

from tailslib.additionalsoftware import (
    ASPDataError,
    add_additional_packages,
    filter_package_details,
    get_additional_packages,
    get_packages_list_path,
    remove_additional_packages)

from tailslib.persistence import (
    has_unlocked_persistence,
    has_persistence,
    is_tails_media_writable,
    launch_persistence_setup,
    PERSISTENCE_DIR)

from tailslib.utils import launch_x_application

_ = gettext.gettext

ASP_STATE_DIR = "/run/live-additional-software"
ASP_STATE_PACKAGES = os.path.join(ASP_STATE_DIR, "packages")
ASP_STATE_INSTALLER_ASKED = os.path.join(ASP_STATE_DIR, "installer-asked")
ASP_LOG_FILE = os.path.join(ASP_STATE_DIR, "log")
OLD_APT_LISTS_DIR = os.path.join(PERSISTENCE_DIR, 'apt', 'lists.old')
APT_ARCHIVES_DIR = "/var/cache/apt/archives"
APT_LISTS_DIR = "/var/lib/apt/lists"


def _exit_if_in_live_build():
    """Exits with success if running inside live-build."""
    if "SOURCE_DATE_EPOCH" in os.environ:
        sys.exit(0)


def _launch_apt_get(specific_args):
    """Launch apt-get with given arguments.

    Launch apt-get with given arguments list, log its standard and error output
    and return its returncode."""
    apt_get_env = os.environ.copy()
    # The environnment provided in GDM PostLogin hooks doesn't contain /sbin/
    # which is required by dpkg. Let's use the default path for root in Tails.
    apt_get_env['PATH'] = "/usr/local/sbin:/usr/local/bin:/usr/sbin:" \
                          "/usr/bin:/sbin:/bin"
    # We will log the output and want it in English when included in bug
    # reports
    apt_get_env['LANG'] = "C"
    apt_get_env['DEBIAN_PRIORITY'] = "critical"
    args = ["apt-get", "--quiet", "--yes"]
    args.extend(specific_args)
    apt_get = subprocess.Popen(args,
                               env=apt_get_env,
                               universal_newlines=True,
                               stderr=subprocess.STDOUT,
                               stdout=subprocess.PIPE)
    for line in iter(apt_get.stdout.readline, ''):
        if not line.startswith('('):
            logging.info(line.rstrip())
    apt_get.wait()
    if apt_get.returncode:
        logging.warning("apt-get exited with returncode %i"
                        % apt_get.returncode)
    return apt_get.returncode


def _notify(title, body="", accept_label="", deny_label="",
            documentation_target="", urgent=False, return_id=False):
    """Display a notification to the user of the live system.

    The notification will show title and body.

    If accept_label or deny_label are set, they will be shown on action buttons
    and the method will wait for user input and return 1 if the button with
    accept_label was clicked or 0 if the button with deny_label was
    clicked.

    If documentation_target is set, a "Documentation" action button will open
    corresponding tails documentation when clicked.

    If return_id is true, returns the notification ID, which may be used to
    close the notification.

    Else, return None.
    """

    cmd = "/usr/local/lib/tails-additional-software-notify"
    if urgent:
        urgent = "urgent"
    else:
        urgent = ""

    try:
        completed_process = subprocess.run(
            [
                "sudo", "-u", LIVE_USERNAME,
                cmd, title, body, accept_label, deny_label,
                documentation_target, urgent
            ],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True
        )
        if completed_process.returncode == 1:
            # sudo failed to execute the command
            raise OSError(completed_process.stderr)
    except OSError as e:
        logging.warning("Warning: unable to notify the user. %s" % e)
        logging.warning("The notification was: %s %s" % (title, body))
        return None

    if return_id:
        for line in completed_process.stdout.splitlines():
            if line.startswith("id="):
                return line[3:]
    else:
        if completed_process.returncode == 0:
            return 1
        elif completed_process.returncode == 3:
            return 0
        else:
            return None


def _notify_failure(summary, details=None):
    """Display a failure notification to the user of the live system.

    The user has the option to edit the configuration or to view the system
    log.
    """
    if details:
        # Translators: Don't translate {details}, it's a placeholder and will
        # be replaced.
        details = _("{details} Please check your list of additional "
                    "software or read the system log to "
                    "understand the problem.").format(details=details)

    else:
        details = _("Please check your list of additional "
                    "software or read the system log to "
                    "understand the problem.")

    action_clicked = _notify(summary, details, _("Show Log"), _("Configure"),
                             urgent=True)
    if action_clicked == 1:
        show_system_log()
    elif action_clicked == 0:
        show_configuration_window()


def _close_notification(notification_id):
    """Close a notification shown to the user of the live system."""
    subprocess.run(
            ["sudo", "-u", LIVE_USERNAME,
             "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/{uid}/bus".format(
                  uid=pwd.getpwnam(LIVE_USERNAME).pw_uid),
             "gdbus", "call",
             "--session",
             "--dest", "org.freedesktop.Notifications",
             "--object-path", "/org/freedesktop/Notifications",
             "--method", "org.freedesktop.Notifications.CloseNotification",
             str(notification_id)],
            stdout=subprocess.DEVNULL)


def _spawn_daemon(func):
    """Spawn func after double-forking.

    Do the UNIX double-fork magic, see Stevens' "Advanced
    Programming in the UNIX Environment" for details (ISBN 0201563177).

    From https://stackoverflow.com/questions/6011235/run-a-program-from-
    python-and-have-it-continue-to-run-after-the-script-is-kille
    """
    try:
        pid = os.fork()
        if pid > 0:
            # parent process, return and keep running
            return
    except OSError as e:
        logging.error("fork #1 failed: %d (%s)" % (e.errno, e.strerror))
        sys.exit(1)

    os.setsid()

    # do second fork
    try:
        pid = os.fork()
        if pid > 0:
            # exit from second parent
            sys.exit(0)
    except OSError as e:
        logging.error("fork #2 failed: %d (%s)" % (e.errno, e.strerror))
        sys.exit(1)

    # do stuff
    func()


def _format_iterable(iterable):
    """Return a nice formatted string with the elements of iterable."""
    iterable = sorted(iterable)

    if len(iterable) == 1:
        return iterable[0]
    elif len(iterable) > 1:
        # Translators: Don't translate {beginning} or {last}, they are
        # placeholders and will be replaced.
        return _("{beginning} and {last}").format(
            beginning=_(", ").join(iterable[:-1]), last=iterable[-1])
    else:
        return str(iterable)


def has_additional_packages_list(search_new_persistence=False):
    """Return true iff a packages list file is found in a persistence.

    Log warnings in syslog.
    The search_new_persistence argument is passed to get_persistence_path.
    """
    try:
        packages_list_path = get_packages_list_path(search_new_persistence)
    except FileNotFoundError as e:
        logging.warning("Warning: {}".format(e))
        return False
    if os.path.isfile(packages_list_path):
        logging.info("Found additional packages list.")
        return True
    else:
        logging.warning("Warning: no configuration file found.")
        return False


def delete_old_apt_lists(old_apt_lists_dir=OLD_APT_LISTS_DIR):
    """Delete the copy of the old APT lists, if any."""
    shutil.rmtree(old_apt_lists_dir)


def save_old_apt_lists(srcdir=APT_LISTS_DIR, destdir=OLD_APT_LISTS_DIR):
    """Save a copy of the APT lists"""
    if os.path.exists(destdir):
        logging.warning("Warning: a copy of the APT lists already exists, "
                        "which should never happen. Removing it.")
        delete_old_apt_lists(destdir)
    shutil.copytree(srcdir, destdir, symlinks=True)


# Note: we can't do nicer delete + move operations because the directory
# we want to replace is bind-mounted. So we have to delete the content
# we want to replace, and then move the content we want to restore.
def restore_old_apt_lists(srcdir=OLD_APT_LISTS_DIR, dstdir=APT_LISTS_DIR):
    """Restore the copy of the old APT lists."""
    # Empty dstdir
    for basename in os.listdir(dstdir):
        path = os.path.join(dstdir, basename)
        if os.path.isfile(path):
            os.remove(path)
        elif os.path.isdir(path):
            shutil.rmtree(path)
    # Move the content of srcdir to dstdir
    for basename in os.listdir(srcdir):
        path = os.path.join(srcdir, basename)
        shutil.move(path, dstdir)


def handle_installed_packages(packages):
    """Configure packages as additional software packages if the user wants to.

    Ask the user if packages should be added to additional software, and
    actually add them if requested.
    """
    logging.info("New packages manually installed: %s" % packages)
    if has_unlocked_persistence(search_new_persistence=True):
        # Translators: Don't translate {packages}, it's a placeholder and will
        # be replaced.
        if _notify(_("Add {packages} to your additional software?").format(
                    packages=_format_iterable(packages)),
                   _("To install it automatically from your persistent "
                     "storage when starting Tails."),
                   _("Install Every Time"),
                   _("Install Only Once"),
                   urgent=True):
            try:
                setup_additional_packages()
                add_additional_packages(packages, search_new_persistence=True)
            except Exception as e:
                _notify_failure(_("The configuration of your additional "
                                  "software failed."))
                raise e
    elif has_persistence():
        # When a package is installed with a persistent storage locked, don't
        # show any notification.
        #
        # People who have a persistent storage but don't unlock it, probably do
        # this only sometimes and for a reason. They probably otherwise unlock
        # their persistent storage most of the time.
        #
        # If they install packages with their persistent storage locked, they
        # probably do it with their persistent storage unlock as well and would
        # learn about this feature when it's most relevant for them.
        logging.warning("Warning: persistence storage is locked, can't add "
                        "additional software.")
    elif is_tails_media_writable():
        # Translators: Don't translate {packages}, it's a placeholder and will
        # be replaced.
        if _notify(_("Add {packages} to your additional software?").format(
                    packages=_format_iterable(packages)),
                   _("To install it automatically when starting Tails, you "
                     "can create a persistent storage and activate the "
                     "<b>Additional Software</b> feature."),
                   _("Create Persistent Storage"),
                   _("Install Only Once"),
                   urgent=True):
            try:
                create_persistence_and_setup_additional_packages(packages)
            except Exception as e:
                _notify_failure(_("The configuration of your additional "
                                  "software failed."),
                                _("Creating your persistent storage "
                                  "failed."))
                raise e
    else:   # It's impossible to have a persistent storage
        logging.warning("Cannot create persistent storage on this media.")
        if not os.path.isfile(ASP_STATE_INSTALLER_ASKED):
            open(ASP_STATE_INSTALLER_ASKED, 'a').close()
            # Translators: Don't translate {packages}, it's a placeholder and
            # will be replaced.
            _notify(_("You could install {packages} automatically when "
                      "starting Tails").format(
                        packages=_format_iterable(packages)),
                    _("To do so, you need to run Tails from a USB stick "
                      "installed using <i>Tails Installer</i>."),
                    documentation_target="install/clone",
                    urgent=True)


def handle_removed_packages(packages):
    """Removes packages from additional software packages if the user wants to.

    Ask the user if packages should be removed from additional software, and
    actually remove them if requested.
    """
    logging.info("Additional packages removed: %s" % packages)
    # Translators: Don't translate {packages}, it's a placeholder and will be
    # replaced.
    if _notify(_("Remove {packages} from your additional software?").format(
                 packages=_format_iterable(packages)),
               # Translators: Don't translate {packages}, it's a placeholder
               # and will be replaced.
               _("This will stop installing {packages} automatically.").format(
                 packages=_format_iterable(packages)),
               _("Remove"),
               _("Cancel"),
               urgent=True):
        try:
            remove_additional_packages(packages, search_new_persistence=True)
        except Exception as e:
            _notify_failure(_("The configuration of your additional "
                              "software failed."))
            raise e


def setup_additional_packages():
    """Enable additional software in persistence."""
    launch_persistence_setup("--no-gui",
                             "--no-display-finished-message",
                             "--force-enable-preset", "AdditionalSoftware")


def create_persistence_and_setup_additional_packages(packages):
    """Create persistence and add packages to its configuration.

    Create a new persistence with additional packages enabled.
    Then add the packages to additional packages configuration.

    packages should be a list of packages names.
    """
    logging.info("Creating new persistent volume")
    launch_persistence_setup("--step", "bootstrap",
                             "--no-display-finished-message",
                             "--force-enable-preset", "AdditionalSoftware")
    add_additional_packages(packages, search_new_persistence=True)
    # show persistence configuration
    launch_persistence_setup()
    # APT lists and APT archive cache will be synchronized at shutdown by
    # tails-synchronize-data-to-new-persistent-volume-on-shutdown.service


def show_configuration_window():
    """Show additional packages configuration window."""
    launch_x_application(LIVE_USERNAME,
                         "/usr/local/bin/tails-additional-software-config")


def show_system_log():
    """Show additional packages configuration window."""
    launch_x_application(LIVE_USERNAME,
                         "/usr/bin/gedit",
                         ASP_LOG_FILE)


def apt_hook_pre():
    """Subcommand to handle Dpkg::Pre-Install-Pkgs."""
    _exit_if_in_live_build()
    logging.info("Saving package changes")

    apt_cache = apt.cache.Cache()

    installed_packages = []
    removed_packages = []

    line = sys.stdin.readline()
    if not line.startswith("VERSION 3"):
        raise ASPDataError("APT data is not version 3")
    line = sys.stdin.readline()
    # Ignore configuration space, which ends with an empty line
    while line != "\n":
        line = sys.stdin.readline()
    # Package action lines
    for line in sys.stdin:
        # Package action lines consist of five fields in Version 2: package
        # name (without architecture qualification even if foreign), old
        # version, direction of version change (< for upgrades, > for
        # downgrades, = for no change), new version, action. The version
        # fields are "-" for no version at all (for example when installing
        # a package for the first time; no version is treated as earlier
        # than any real version, so that is an upgrade, indicated as - <
        # 1.23.4). The action field is "**CONFIGURE**" if the package is
        # being configured, "**REMOVE**" if it is being removed, or the
        # filename of a .deb file if it is being unpacked.
        #
        # In Version 3 after each version field follows the architecture of
        # this version, which is "-" if there is no version, and a field
        # showing the MultiArch type "same", "foreign", "allowed" or "none".
        # Note that "none" is an incorrect typename which is just kept to
        # remain compatible, it should be read as "no" and users are
        # encouraged to support both.
        #
        # Example:
        #
        # colordif - - none < 1.0.16-1 all none **CONFIGURE**
        package_name, old_version, old_arch, old_multiarch, direction, \
                new_version, new_arch, new_multiarch, action = line.split()
        if action.endswith(".deb"):
            # Filter packages that will only be upgraded
            if not apt_cache[package_name].is_installed:
                installed_packages.append(package_name)
        elif action.endswith("**REMOVE**"):
            removed_packages.append(package_name)

    result = {"installed": installed_packages, "removed": removed_packages}
    with open(ASP_STATE_PACKAGES, 'w') as f:
        json.dump(result, f)


def apt_hook_post():
    """Subcommand to handle Dpkg::Post-Invoke.

    Retrieve the list of packages saved by apt_hook_pre, filter packages not
    interesting and pass the resulting list to the appropriate method.
    """
    _exit_if_in_live_build()
    logging.info("Examining package changes")

    with open(ASP_STATE_PACKAGES) as f:
        packages = json.load(f)
    os.remove(ASP_STATE_PACKAGES)

    additional_packages_names = {
        filter_package_details(pkg) for pkg in
        get_additional_packages(search_new_persistence=True)
    }

    apt_cache = apt.cache.Cache()
    # Filter automatically installed packages and packages already configured
    # as additional software
    new_manually_installed_packages = {
        pkg for pkg in packages["installed"] if (
            not apt_cache[pkg].is_auto_installed and
            pkg not in additional_packages_names)
    }

    if new_manually_installed_packages:
        handle_installed_packages(new_manually_installed_packages)

    # Filter non-additional software packages
    additional_packages_removed = set(packages["removed"]).intersection(
        additional_packages_names)
    if additional_packages_removed:
        handle_removed_packages(additional_packages_removed)


def install_additional_packages(upgrade_mode=False):
    """Subcommand which activates and installs all additional packages.

    If upgrade_mode is True, don't attempt to restore old apt lists and don't
    notify the user using desktop notifications."""
    logging.info("Starting to install additional software...")

    if not has_additional_packages_list():
        return True

    # If a copy of old APT lists is found, then the previous upgrade
    # attempt has not completed successfully (it may have failed e.g.
    # due to network problems, or it may have been interrupted).
    # In many of these cases, the APT package cache lacks some
    # packages the new APT lists reference, so the (offline)
    # installation step below in this function will fail. To avoid
    # that, we restore the old APT lists: there are greater chances
    # that the APT packages cache still has the corresponding packages.
    if os.path.isdir(OLD_APT_LISTS_DIR) and not upgrade_mode:
        logging.warning("Found a copy of old APT lists, restoring it.")
        try:
            restore_old_apt_lists()
        except Exception as e:
            logging.warning("Restoring old APT lists failed with %r, "
                            "deleting them and proceeding anyway." % e)
        # In all cases, delete the old APT lists: if they could be
        # restored we don't need them anymore (and we don't want to
        # restore them again next time); if they could not be
        # restored, chances are restoration will fail next time
        # as well.
        delete_old_apt_lists()

    packages = get_additional_packages()
    if not packages:
        logging.warning("Warning: no packages to install, exiting")
        return True
    if not upgrade_mode:
        installing_notification_id = _notify(
            _("Installing your additional software from persistent "
              "storage..."),
            _("This can take several minutes."),
            return_id=True)
    logging.info("Will install the following packages: %s"
                 % " ".join(packages))
    apt_get_returncode = _launch_apt_get(
        ["--no-remove",
         "--option", "DPkg::Options::=--force-confold",
         "install"] + list(packages))
    if apt_get_returncode:
        logging.warning("Warning: installation of %s failed"
                        % " ".join(packages))
        if not upgrade_mode:
            _close_notification(installing_notification_id)
            _notify_failure(_("The installation of your additional software "
                              "failed"))
        return False
    else:
        logging.info("Installation completed successfully.")
        if not upgrade_mode:
            _close_notification(installing_notification_id)
            # XXX: there should be a "Configure" button in this notification.
            # However, the easy way to implement it makes this process not
            # return until the notification is clicked. The notification
            # process could be detached, and handle the "configure" action
            # itself.
            #  if _notify(_("Additional software installed successfully"),
            #             accept_label=_("Configure")):
            #      show_configuration_window()
            _notify(_("Additional software installed successfully"))
        return True


def upgrade_additional_packages():
    """Subcommand which upgrades all additional packages."""
    logging.info("Starting to upgrade additional software...")

    if not has_additional_packages_list():
        return True

    # Save a copy of APT lists that we'll delete only once the upgrade
    # has succeeded, to ensure that the APT packages cache is up-to-date
    # wrt. the APT lists.
    logging.info("Saving old APT lists...")
    save_old_apt_lists()

    apt_get_returncode = _launch_apt_get(["update"])
    if apt_get_returncode:
        logging.warning("Warning: the update failed.")
        _notify_failure(_("The check for upgrades of your additional software "
                          "failed"),
                        _("Please check your network connection, "
                          "restart Tails, or read the system log to "
                          "understand the problem."))
        return False
    if install_additional_packages(upgrade_mode=True):
        logging.info("The upgrade was successful.")
    else:
        _notify_failure(_("The upgrade of your additional software failed"),
                        _("Please check your network connection, "
                          "restart Tails, or read the system log to "
                          "understand the problem."))
        return False

    # We now know that the APT packages cache is up-to-date wrt. the APT lists,
    # so we can delete the copy of the old lists
    delete_old_apt_lists()

    # Remove outdated packages from the local package cache. This is needed as
    # we disable apt-daily.timer, which would else take care of this cleanup.
    # We do this after the upgrade has succeeded so that the old packages
    # remain available in the cache in case we have to restore the old lists.
    # In the past we did this before upgrading in order to remove the
    # i386 packages from the cache before downloading amd64 ones, but
    # this does not matter anymore now that all persistent volumes
    # must have been upgraded already.
    apt_get_returncode = _launch_apt_get(["autoclean"])
    if apt_get_returncode:
        logging.warning("Warning: autoclean failed.")
    return True


def print_help():
    """Subcommand which displays help."""
    sys.stderr.write("Usage: %s <subcommand>\n" % program_name)
    sys.stderr.write("""Subcommands:
    install: install additional software
    upgrade: upgrade additional software\n""")


if __name__ == "__main__":
    program_name = os.path.basename(sys.argv[0])

    # Exits with success if running inside live-build.
    if "SOURCE_DATE_EPOCH" in os.environ:
        sys.exit(0)

    # Set loglevel if debug is found in kernel command line.
    with open('/proc/cmdline') as cmdline_fd:
        cmdline = cmdline_fd.read()
    if "DEBUG" in os.environ or "debug" in cmdline.split():
        log_level = logging.DEBUG
        log_format = "[%(levelname)s] %(filename)s:%(lineno)d " \
                     "%(funcName)s: %(message)s"
    else:
        log_level = logging.INFO
        log_format = "[%(levelname)s] %(message)s"
    stderr_handler = logging.StreamHandler()
    file_handler = logging.FileHandler(ASP_LOG_FILE)
    logging.basicConfig(format=log_format,
                        handlers=[stderr_handler, file_handler],
                        level=log_level)

    gettext.install("tails")

    if len(sys.argv) < 2:
        print_help()
        sys.exit(2)

    if sys.argv[1] == "install":
        if not install_additional_packages():
            sys.exit(150)
    elif sys.argv[1] == "upgrade":
        if not upgrade_additional_packages():
            sys.exit(151)
    elif sys.argv[1] == "apt-pre":
        apt_hook_pre()
    elif sys.argv[1] == "apt-post":
        _spawn_daemon(apt_hook_post)
    else:
        print_help()
        sys.exit(2)