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bots: Audit filesystem access.

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This adds a safe function for opening files via
ExternalBotHandler. This restricts open calls to a bot's
local directory.

Finalizes #9
This commit is contained in:
derAnfaenger 2017-07-25 16:04:38 +02:00
parent e619c19b36
commit f3eaa381f6
2 changed files with 19 additions and 5 deletions
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18
zulip_bots/zulip_bots/lib.py
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@ -47,12 +47,13 @@ class RateLimit(object):
sys.exit(1)
class ExternalBotHandler(object):
def __init__(self, client):
# type: (Client) -> None
def __init__(self, client, root_dir):
# type: (Client, string) -> None
# Only expose a subset of our Client's functionality
user_profile = client.get_profile()
self._rate_limit = RateLimit(20, 5)
self._client = client
self._root_dir = root_dir
try:
self.full_name = user_profile['full_name']
self.email = user_profile['email']
@ -106,6 +107,16 @@ class ExternalBotHandler(object):
raise
return dict(config.items(section))
def open(self, filepath):
# type: (str) -> None
filepath = os.path.normpath(filepath)
abs_filepath = os.path.join(self._root_dir, filepath)
if abs_filepath.startswith(self._root_dir):
return open(abs_filepath)
else:
raise PermissionError("Cannot open file \"{}\". Bots may only access "
"files in their local directory.".format(abs_filepath))
class StateHandler(object):
def __init__(self):
# type: () -> None
@ -136,7 +147,8 @@ def run_message_handler_for_bot(lib_module, quiet, config_file, bot_name):
#
# Make sure you set up your ~/.zuliprc
client = Client(config_file=config_file, client="Zulip{}Bot".format(bot_name.capitalize()))
restricted_client = ExternalBotHandler(client)
bot_dir = os.path.dirname(lib_module.__file__)
restricted_client = ExternalBotHandler(client, bot_dir)
message_handler = lib_module.handler_class()
if hasattr(message_handler, 'initialize'):