Implement MSC3231: Token authenticated registration (#10142)

Signed-off-by: Callum Brown <callum@calcuode.com>

This is part of my GSoC project implementing [MSC3231](https://github.com/matrix-org/matrix-doc/pull/3231).

2 files changed, 26 insertions, 0 deletions

diff --git a/synapse/config/ratelimiting.py b/synapse/config/ratelimiting.py
index 7a8d5851c4..f856327bd8 100644
--- a/synapse/config/ratelimiting.py
+++ b/synapse/config/ratelimiting.py
@@ -79,6 +79,11 @@ class RatelimitConfig(Config):
 
         self.rc_registration = RateLimitConfig(config.get("rc_registration", {}))
 
+        self.rc_registration_token_validity = RateLimitConfig(
+            config.get("rc_registration_token_validity", {}),
+            defaults={"per_second": 0.1, "burst_count": 5},
+        )
+
         rc_login_config = config.get("rc_login", {})
         self.rc_login_address = RateLimitConfig(rc_login_config.get("address", {}))
         self.rc_login_account = RateLimitConfig(rc_login_config.get("account", {}))
@@ -143,6 +148,8 @@ class RatelimitConfig(Config):
         #     is using
         #   - one for registration that ratelimits registration requests based on the
         #     client's IP address.
+        #   - one for checking the validity of registration tokens that ratelimits
+        #     requests based on the client's IP address.
         #   - one for login that ratelimits login requests based on the client's IP
         #     address.
         #   - one for login that ratelimits login requests based on the account the
@@ -171,6 +178,10 @@ class RatelimitConfig(Config):
         #  per_second: 0.17
         #  burst_count: 3
         #
+        #rc_registration_token_validity:
+        #  per_second: 0.1
+        #  burst_count: 5
+        #
         #rc_login:
         #  address:
         #    per_second: 0.17
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 0ad919b139..7cffdacfa5 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -33,6 +33,9 @@ class RegistrationConfig(Config):
         self.registrations_require_3pid = config.get("registrations_require_3pid", [])
         self.allowed_local_3pids = config.get("allowed_local_3pids", [])
         self.enable_3pid_lookup = config.get("enable_3pid_lookup", True)
+        self.registration_requires_token = config.get(
+            "registration_requires_token", False
+        )
         self.registration_shared_secret = config.get("registration_shared_secret")
 
         self.bcrypt_rounds = config.get("bcrypt_rounds", 12)
@@ -140,6 +143,9 @@ class RegistrationConfig(Config):
                 "mechanism by removing the `access_token_lifetime` option."
             )
 
+        # The fallback template used for authenticating using a registration token
+        self.registration_token_template = self.read_template("registration_token.html")
+
         # The success template used during fallback auth.
         self.fallback_success_template = self.read_template("auth_success.html")
 
@@ -199,6 +205,15 @@ class RegistrationConfig(Config):
         #
         #enable_3pid_lookup: true
 
+        # Require users to submit a token during registration.
+        # Tokens can be managed using the admin API:
+        # https://matrix-org.github.io/synapse/latest/usage/administration/admin_api/registration_tokens.html
+        # Note that `enable_registration` must be set to `true`.
+        # Disabling this option will not delete any tokens previously generated.
+        # Defaults to false. Uncomment the following to require tokens:
+        #
+        #registration_requires_token: true
+
         # If set, allows registration of standard or admin accounts by anyone who
         # has the shared secret, even if registration is otherwise disabled.
         #