Config option to inhibit 3PID errors on /requestToken

Adds a request_token_inhibit_errors configuration flag (disabled by
default) which, if enabled, change the behaviour of all /requestToken
endpoints so that they return a 200 and a fake sid if the 3PID was/was
not found associated with an account (depending on the endpoint),
instead of an error.

Co-Authored-By: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
This commit is contained in:
Brendan Abolivier 2020-04-21 16:33:01 +02:00
parent 88bb6c27e1
commit 69ad7cc13b
No known key found for this signature in database
GPG Key ID: 1E015C145F1916CD
7 changed files with 121 additions and 3 deletions

1
changelog.d/7315.feature Normal file
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@ -0,0 +1 @@
Allow `/requestToken` endpoints to hide the existence (or lack thereof) of 3PID associations on the homeserver.

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@ -409,6 +409,16 @@ retention:
# longest_max_lifetime: 1y
# interval: 1d
# Inhibits the /requestToken endpoints from returning an error that might leak
# information about whether an e-mail address is in use or not on this
# homeserver.
# Note that for some endpoints the error situation is the e-mail already being
# used, and for others the error is entering the e-mail being unused.
# If this option is enabled, instead of returning an error, these endpoints will
# act as if no error happened and return a fake session ID ('sid') to clients.
#
#request_token_inhibit_3pid_errors: true
## TLS ##

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@ -507,6 +507,17 @@ class ServerConfig(Config):
self.enable_ephemeral_messages = config.get("enable_ephemeral_messages", False)
# Inhibits the /requestToken endpoints from returning an error that might leak
# information about whether an e-mail address is in use or not on this
# homeserver, and instead return a 200 with a fake sid if this kind of error is
# met, without sending anything.
# This is a compromise between sending an email, which could be a spam vector,
# and letting the client know which email address is bound to an account and
# which one isn't.
self.request_token_inhibit_3pid_errors = config.get(
"request_token_inhibit_3pid_errors", False,
)
def has_tls_listener(self) -> bool:
return any(l["tls"] for l in self.listeners)
@ -967,6 +978,16 @@ class ServerConfig(Config):
# - shortest_max_lifetime: 3d
# longest_max_lifetime: 1y
# interval: 1d
# Inhibits the /requestToken endpoints from returning an error that might leak
# information about whether an e-mail address is in use or not on this
# homeserver.
# Note that for some endpoints the error situation is the e-mail already being
# used, and for others the error is entering the e-mail being unused.
# If this option is enabled, instead of returning an error, these endpoints will
# act as if no error happened and return a fake session ID ('sid') to clients.
#
#request_token_inhibit_3pid_errors: true
"""
% locals()
)

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@ -30,7 +30,7 @@ from synapse.http.servlet import (
)
from synapse.push.mailer import Mailer, load_jinja2_templates
from synapse.util.msisdn import phone_number_to_msisdn
from synapse.util.stringutils import assert_valid_client_secret
from synapse.util.stringutils import assert_valid_client_secret, random_string
from synapse.util.threepids import check_3pid_allowed
from ._base import client_patterns, interactive_auth_handler
@ -100,6 +100,11 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
)
if existing_user_id is None:
if self.config.request_token_inhibit_3pid_errors:
# Make the client think the operation succeeded. See the rationale in the
# comments for request_token_inhibit_3pid_errors.
return 200, {"sid": random_string(16)}
raise SynapseError(400, "Email not found", Codes.THREEPID_NOT_FOUND)
if self.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
@ -378,6 +383,11 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
)
if existing_user_id is not None:
if self.config.request_token_inhibit_3pid_errors:
# Make the client think the operation succeeded. See the rationale in the
# comments for request_token_inhibit_3pid_errors.
return 200, {"sid": random_string(16)}
raise SynapseError(400, "Email is already in use", Codes.THREEPID_IN_USE)
if self.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
@ -441,6 +451,11 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
existing_user_id = await self.store.get_user_id_by_threepid("msisdn", msisdn)
if existing_user_id is not None:
if self.hs.config.request_token_inhibit_3pid_errors:
# Make the client think the operation succeeded. See the rationale in the
# comments for request_token_inhibit_3pid_errors.
return 200, {"sid": random_string(16)}
raise SynapseError(400, "MSISDN is already in use", Codes.THREEPID_IN_USE)
if not self.hs.config.account_threepid_delegate_msisdn:

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@ -49,7 +49,7 @@ from synapse.http.servlet import (
from synapse.push.mailer import load_jinja2_templates
from synapse.util.msisdn import phone_number_to_msisdn
from synapse.util.ratelimitutils import FederationRateLimiter
from synapse.util.stringutils import assert_valid_client_secret
from synapse.util.stringutils import assert_valid_client_secret, random_string
from synapse.util.threepids import check_3pid_allowed
from ._base import client_patterns, interactive_auth_handler
@ -135,6 +135,11 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
)
if existing_user_id is not None:
if self.hs.config.request_token_inhibit_3pid_errors:
# Make the client think the operation succeeded. See the rationale in the
# comments for request_token_inhibit_3pid_errors.
return 200, {"sid": random_string(16)}
raise SynapseError(400, "Email is already in use", Codes.THREEPID_IN_USE)
if self.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
@ -202,6 +207,11 @@ class MsisdnRegisterRequestTokenRestServlet(RestServlet):
)
if existing_user_id is not None:
if self.hs.config.request_token_inhibit_3pid_errors:
# Make the client think the operation succeeded. See the rationale in the
# comments for request_token_inhibit_3pid_errors.
return 200, {"sid": random_string(16)}
raise SynapseError(
400, "Phone number is already in use", Codes.THREEPID_IN_USE
)

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@ -178,6 +178,22 @@ class PasswordResetTestCase(unittest.HomeserverTestCase):
# Assert we can't log in with the new password
self.attempt_wrong_password_login("kermit", new_password)
@unittest.override_config({"request_token_inhibit_3pid_errors": True})
def test_password_reset_bad_email_inhibit_error(self):
"""Test that triggering a password reset with an email address that isn't bound
to an account doesn't leak the lack of binding for that address if configured
that way.
"""
self.register_user("kermit", "monkey")
self.login("kermit", "monkey")
email = "test@example.com"
client_secret = "foobar"
session_id = self._request_token(email, client_secret)
self.assertIsNotNone(session_id)
def _request_token(self, email, client_secret):
request, channel = self.make_request(
"POST",

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@ -33,7 +33,11 @@ from tests import unittest
class RegisterRestServletTestCase(unittest.HomeserverTestCase):
servlets = [register.register_servlets]
servlets = [
login.register_servlets,
register.register_servlets,
synapse.rest.admin.register_servlets,
]
url = b"/_matrix/client/r0/register"
def default_config(self, name="test"):
@ -260,6 +264,47 @@ class RegisterRestServletTestCase(unittest.HomeserverTestCase):
[["m.login.email.identity"]], (f["stages"] for f in flows)
)
@unittest.override_config(
{
"request_token_inhibit_3pid_errors": True,
"public_baseurl": "https://test_server",
"email": {
"smtp_host": "mail_server",
"smtp_port": 2525,
"notif_from": "sender@host",
},
}
)
def test_request_token_existing_email_inhibit_error(self):
"""Test that requesting a token via this endpoint doesn't leak existing
associations if configured that way.
"""
user_id = self.register_user("kermit", "monkey")
self.login("kermit", "monkey")
email = "test@example.com"
# Add a threepid
self.get_success(
self.hs.get_datastore().user_add_threepid(
user_id=user_id,
medium="email",
address=email,
validated_at=0,
added_at=0,
)
)
request, channel = self.make_request(
"POST",
b"register/email/requestToken",
{"client_secret": "foobar", "email": email, "send_attempt": 1},
)
self.render(request)
self.assertEquals(200, channel.code, channel.result)
self.assertIsNotNone(channel.json_body.get("sid"))
class AccountValidityTestCase(unittest.HomeserverTestCase):