# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import logging
import os
import pwd
import stat

from autotest_lib.client.bin import utils
from autotest_lib.client.common_lib import error
from autotest_lib.client.cros import constants, cros_ui_test, cryptohome, login


class security_ProfilePermissions(cros_ui_test.UITest):
    version = 2
    _HOMEDIR_MODE = 0710

    def initialize(self, creds='$default'):
        try:
            super(security_ProfilePermissions, self).initialize(creds)
        except Exception as err:
            raise error.TestFailRetry(err)

    def check_owner_mode(self, path, expected_owner, expected_mode):
        """
        Checks if the file/directory at 'path' is owned by 'expected_owner'
        with permissions matching 'expected_mode'.
        Returns True if they match, else False.
        Logs any mismatches to logging.error.
        """
        s = os.stat(path)
        actual_owner = pwd.getpwuid(s.st_uid).pw_name
        actual_mode = stat.S_IMODE(s.st_mode)
        if (expected_owner != actual_owner or
            expected_mode != actual_mode):
            logging.error("%s - Expected %s:%s, saw %s:%s" %
                          (path, expected_owner, oct(expected_mode),
                           actual_owner, oct(actual_mode)))
            return False
        else:
            return True


    def run_once(self):
        username = self.username or cryptohome.GUEST_USER_NAME
        login.wait_for_cryptohome(username)

        """Check permissions within cryptohome for anything too permissive."""
        passes = []

        homepath = "/home/chronos"
        passes.append(self.check_owner_mode(homepath, "chronos", 0755))

        user_mountpt = cryptohome.user_path(username)
        passes.append(self.check_owner_mode(user_mountpt, "chronos",
                                            self._HOMEDIR_MODE))

        # TODO(benchan): Refactor the following code to use some helper
        # functions instead of find commands.

        # An array of shell commands, each representing a test that
        # passes if it emits no output. The first test is the main one.
        # In general, writable by anyone else is bad, as is owned by
        # anyone else. Any exceptions to that are pruned out of the
        # first test and checked individually by subsequent tests.
        cmds = [
            ('find -L "%s" -path "%s" -o '
             # Avoid false-positives on SingletonLock, SingletonCookie, etc.
             ' \\( -name "Singleton*" -a -type l \\) -o '
             ' -path "%s/user" -prune -o '
             ' -path "%s/Downloads" -prune -o '
             ' -path "%s/flimflam" -prune -o '
             ' -path "%s/shill" -prune -o '
             ' -path "%s/.chaps" -prune -o '
             ' -path "%s/u-*" -prune -o '
             ' \\( -perm /022 -o \\! -user chronos \\) -ls') %
            (homepath, homepath, homepath, user_mountpt, user_mountpt, user_mountpt,
            user_mountpt, homepath),
            # /home/chronos/user and /home/chronos/user/Downloads are owned by
            # the chronos-access group and with a group execute permission.
            'find -L "%s" -maxdepth 0 \\( \\! -perm 710 '
            '-o \\! -user chronos -o \\! -group chronos-access \\) -ls' %
            user_mountpt,
            'find -L "%s/Downloads" -maxdepth 0 \\( \\! -perm 710 '
            '-o \\! -user chronos -o \\! -group chronos-access \\) -ls' %
            user_mountpt,
            'find -L "%s/flimflam" \\( -perm /077 -o \\! -user root \\) -ls' %
            user_mountpt,
            'find -L "%s/shill" \\( -perm /077 -o \\! -user root \\) -ls' %
            user_mountpt,
            'find -L "%s/.chaps -name auth_data_salt -prune -o '
            '\\! -user chaps -o \\! -group chronos-access -o -perm /027 -ls' %
            user_mountpt,
            'find -L "%s/.chaps -name auth_data_salt -a '
            '\\( \\! -user root -o -perm /077 \\) -ls' %
            user_mountpt,
        ]

        for cmd in cmds:
            cmd_output = utils.system_output(cmd, ignore_status=True)
            if cmd_output:
                passes.append(False)
                logging.error(cmd_output)

        # This next section only applies if we have a real vault mounted
        # (ie, not a BWSI tmpfs).
        if cryptohome.is_vault_mounted(
                username,
                device_regex=constants.CRYPTOHOME_DEV_REGEX_REGULAR_USER):
            # Also check the permissions of the underlying vault and
            # supporting directory structure.
            vaultpath = cryptohome.get_mounted_vault_devices(username)[0]

            passes.append(self.check_owner_mode(vaultpath, "root", 0700))
            # crbug.com/265725: Avoid winning a race with cryptohome/chmod.
            # Poll for permissions on master.0 to settle.
            check = lambda: self.check_owner_mode(vaultpath + "/../master.0",
                                                  "root", 0600)
            utils.poll_for_condition(check, desc="permissions to settle",
                                     timeout=60, sleep_interval=2)
            passes.append(self.check_owner_mode(vaultpath + "/../",
                                                "root", 0700))
            passes.append(self.check_owner_mode(vaultpath + "/../../",
                                                "root", 0700))

        if False in passes:
            raise error.TestFail('Bad permissions found on cryptohome files')