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diff --git a/docs/sso_mapping_providers.md b/docs/sso_mapping_providers.md new file mode 100644 index 0000000000..abea432343 --- /dev/null +++ b/docs/sso_mapping_providers.md @@ -0,0 +1,148 @@ +# SSO Mapping Providers + +A mapping provider is a Python class (loaded via a Python module) that +works out how to map attributes of a SSO response to Matrix-specific +user attributes. Details such as user ID localpart, displayname, and even avatar +URLs are all things that can be mapped from talking to a SSO service. + +As an example, a SSO service may return the email address +"john.smith@example.com" for a user, whereas Synapse will need to figure out how +to turn that into a displayname when creating a Matrix user for this individual. +It may choose `John Smith`, or `Smith, John [Example.com]` or any number of +variations. As each Synapse configuration may want something different, this is +where SAML mapping providers come into play. + +SSO mapping providers are currently supported for OpenID and SAML SSO +configurations. Please see the details below for how to implement your own. + +External mapping providers are provided to Synapse in the form of an external +Python module. You can retrieve this module from [PyPi](https://pypi.org) or elsewhere, +but it must be importable via Synapse (e.g. it must be in the same virtualenv +as Synapse). The Synapse config is then modified to point to the mapping provider +(and optionally provide additional configuration for it). + +## OpenID Mapping Providers + +The OpenID mapping provider can be customized by editing the +`oidc_config.user_mapping_provider.module` config option. + +`oidc_config.user_mapping_provider.config` allows you to provide custom +configuration options to the module. Check with the module's documentation for +what options it provides (if any). The options listed by default are for the +user mapping provider built in to Synapse. If using a custom module, you should +comment these options out and use those specified by the module instead. + +### Building a Custom OpenID Mapping Provider + +A custom mapping provider must specify the following methods: + +* `__init__(self, parsed_config)` + - Arguments: + - `parsed_config` - A configuration object that is the return value of the + `parse_config` method. You should set any configuration options needed by + the module here. +* `parse_config(config)` + - This method should have the `@staticmethod` decoration. + - Arguments: + - `config` - A `dict` representing the parsed content of the + `oidc_config.user_mapping_provider.config` homeserver config option. + Runs on homeserver startup. Providers should extract and validate + any option values they need here. + - Whatever is returned will be passed back to the user mapping provider module's + `__init__` method during construction. +* `get_remote_user_id(self, userinfo)` + - Arguments: + - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user + information from. + - This method must return a string, which is the unique identifier for the + user. Commonly the ``sub`` claim of the response. +* `map_user_attributes(self, userinfo, token)` + - This method should be async. + - Arguments: + - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user + information from. + - `token` - A dictionary which includes information necessary to make + further requests to the OpenID provider. + - Returns a dictionary with two keys: + - localpart: A required string, used to generate the Matrix ID. + - displayname: An optional string, the display name for the user. + +### Default OpenID Mapping Provider + +Synapse has a built-in OpenID mapping provider if a custom provider isn't +specified in the config. It is located at +[`synapse.handlers.oidc_handler.JinjaOidcMappingProvider`](../synapse/handlers/oidc_handler.py). + +## SAML Mapping Providers + +The SAML mapping provider can be customized by editing the +`saml2_config.user_mapping_provider.module` config option. + +`saml2_config.user_mapping_provider.config` allows you to provide custom +configuration options to the module. Check with the module's documentation for +what options it provides (if any). The options listed by default are for the +user mapping provider built in to Synapse. If using a custom module, you should +comment these options out and use those specified by the module instead. + +### Building a Custom SAML Mapping Provider + +A custom mapping provider must specify the following methods: + +* `__init__(self, parsed_config)` + - Arguments: + - `parsed_config` - A configuration object that is the return value of the + `parse_config` method. You should set any configuration options needed by + the module here. +* `parse_config(config)` + - This method should have the `@staticmethod` decoration. + - Arguments: + - `config` - A `dict` representing the parsed content of the + `saml_config.user_mapping_provider.config` homeserver config option. + Runs on homeserver startup. Providers should extract and validate + any option values they need here. + - Whatever is returned will be passed back to the user mapping provider module's + `__init__` method during construction. +* `get_saml_attributes(config)` + - This method should have the `@staticmethod` decoration. + - Arguments: + - `config` - A object resulting from a call to `parse_config`. + - Returns a tuple of two sets. The first set equates to the SAML auth + response attributes that are required for the module to function, whereas + the second set consists of those attributes which can be used if available, + but are not necessary. +* `get_remote_user_id(self, saml_response, client_redirect_url)` + - Arguments: + - `saml_response` - A `saml2.response.AuthnResponse` object to extract user + information from. + - `client_redirect_url` - A string, the URL that the client will be + redirected to. + - This method must return a string, which is the unique identifier for the + user. Commonly the ``uid`` claim of the response. +* `saml_response_to_user_attributes(self, saml_response, failures, client_redirect_url)` + - Arguments: + - `saml_response` - A `saml2.response.AuthnResponse` object to extract user + information from. + - `failures` - An `int` that represents the amount of times the returned + mxid localpart mapping has failed. This should be used + to create a deduplicated mxid localpart which should be + returned instead. For example, if this method returns + `john.doe` as the value of `mxid_localpart` in the returned + dict, and that is already taken on the homeserver, this + method will be called again with the same parameters but + with failures=1. The method should then return a different + `mxid_localpart` value, such as `john.doe1`. + - `client_redirect_url` - A string, the URL that the client will be + redirected to. + - This method must return a dictionary, which will then be used by Synapse + to build a new user. The following keys are allowed: + * `mxid_localpart` - Required. The mxid localpart of the new user. + * `displayname` - The displayname of the new user. If not provided, will default to + the value of `mxid_localpart`. + * `emails` - A list of emails for the new user. If not provided, will + default to an empty list. + +### Default SAML Mapping Provider + +Synapse has a built-in SAML mapping provider if a custom provider isn't +specified in the config. It is located at +[`synapse.handlers.saml_handler.DefaultSamlMappingProvider`](../synapse/handlers/saml_handler.py). |