# Copyright (C) 2011-2018 by the Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.
""" Cross-Site Request Forgery checker """
import time
import urllib
import marshal
import binascii
from Mailman import mm_cfg
from Mailman.Logging.Syslog import syslog
from Mailman.Utils import UnobscureEmail, sha_new
keydict = {
'user': mm_cfg.AuthUser,
'poster': mm_cfg.AuthListPoster,
'moderator': mm_cfg.AuthListModerator,
'admin': mm_cfg.AuthListAdmin,
'site': mm_cfg.AuthSiteAdmin,
}
def csrf_token(mlist, contexts, user=None):
""" create token by mailman cookie generation algorithm """
if user:
# Unmunge a munged email address.
user = UnobscureEmail(urllib.unquote(user))
for context in contexts:
key, secret = mlist.AuthContextInfo(context, user)
if key:
break
else:
return None # not authenticated
issued = int(time.time())
mac = sha_new(secret + `issued`).hexdigest()
keymac = '%s:%s' % (key, mac)
token = binascii.hexlify(marshal.dumps((issued, keymac)))
return token
def csrf_check(mlist, token, options_user=None):
""" check token by mailman cookie validation algorithm """
try:
issued, keymac = marshal.loads(binascii.unhexlify(token))
key, received_mac = keymac.split(':', 1)
if not key.startswith(mlist.internal_name() + '+'):
return False
key = key[len(mlist.internal_name()) + 1:]
if '+' in key:
key, user = key.split('+', 1)
else:
user = None
if user:
# This is for CVE-2021-42097. The token is a user token because
# of the fix for CVE-2021-42096 but it must match the user for
# whom the options page is requested.
raw_user = UnobscureEmail(urllib.unquote(user))
if options_user and options_user != raw_user:
syslog('mischief',
'Form for user %s submitted with CSRF token '
'issued for %s.',
options_user, raw_user)
return False
context = keydict.get(key)
key, secret = mlist.AuthContextInfo(context, user)
assert key
mac = sha_new(secret + `issued`).hexdigest()
if (mac == received_mac
and 0 < time.time() - issued < mm_cfg.FORM_LIFETIME):
return True
return False
except (AssertionError, ValueError, TypeError):
return False
