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b064559652
This ensures that even if it were possible to create an MIT Kerberos account with a malicious username and/or hack webathena to pretend that's the case, one couldn't do anything malicious. This security improvement only impacts a single installation of Zulip where Zephyr mirroring is in use that has already had the fix applied, so there's no reason to do a security notice for it. Found by Graham Bleaney using pysa.
62 lines
2.3 KiB
Python
62 lines
2.3 KiB
Python
from django.conf import settings
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from django.http import HttpResponse, HttpRequest
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from django.utils.translation import ugettext as _
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from zerver.decorator import authenticated_json_view
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from zerver.lib.ccache import make_ccache
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from zerver.lib.request import has_request_variables, REQ
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from zerver.lib.response import json_success, json_error
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from zerver.lib.users import get_api_key
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from zerver.models import UserProfile
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import base64
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import logging
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import re
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import subprocess
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import ujson
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from typing import Optional
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# Hack for mit.edu users whose Kerberos usernames don't match what they zephyr
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# as. The key is for Kerberos and the value is for zephyr.
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kerberos_alter_egos = {
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'golem': 'ctl',
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}
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@authenticated_json_view
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@has_request_variables
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def webathena_kerberos_login(request: HttpRequest, user_profile: UserProfile,
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cred: Optional[str]=REQ(default=None)) -> HttpResponse:
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global kerberos_alter_egos
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if cred is None:
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return json_error(_("Could not find Kerberos credential"))
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if not user_profile.realm.webathena_enabled:
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return json_error(_("Webathena login not enabled"))
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try:
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parsed_cred = ujson.loads(cred)
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user = parsed_cred["cname"]["nameString"][0]
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if user in kerberos_alter_egos:
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user = kerberos_alter_egos[user]
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assert(user == user_profile.email.split("@")[0])
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# Limit characters in usernames to valid MIT usernames
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# This is important for security since DNS is not secure.
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assert(re.match(r'^[a-z0-9_.-]+$', user) is not None)
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ccache = make_ccache(parsed_cred)
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except Exception:
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return json_error(_("Invalid Kerberos cache"))
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# TODO: Send these data via (say) rabbitmq
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try:
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api_key = get_api_key(user_profile)
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subprocess.check_call(["ssh", settings.PERSONAL_ZMIRROR_SERVER, "--",
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"/home/zulip/python-zulip-api/zulip/integrations/zephyr/process_ccache",
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user,
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api_key,
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base64.b64encode(ccache).decode("utf-8")])
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except Exception:
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logging.exception("Error updating the user's ccache")
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return json_error(_("We were unable to setup mirroring for you"))
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return json_success()
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