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diff --git a/docs/saml_mapping_providers.md b/docs/saml_mapping_providers.md new file mode 100644 index 0000000000..92f2380488 --- /dev/null +++ b/docs/saml_mapping_providers.md @@ -0,0 +1,77 @@ +# SAML Mapping Providers + +A SAML mapping provider is a Python class (loaded via a Python module) that +works out how to map attributes of a SAML response object 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. + +## Enabling Providers + +External mapping providers are provided to Synapse in the form of an external +Python module. Retrieve this module from [PyPi](https://pypi.org) or elsewhere, +then tell Synapse where to look for the handler class 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 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. +* `saml_response_to_user_attributes(self, saml_response, failures)` + - 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`. + - 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`. +* `parse_config(config)` + - This method should have the `@staticmethod` decoration. + - Arguments: + - `config` - A `dict` representing the parsed content of the + `saml2_config.user_mapping_provider.config` homeserver config option. + Runs on homeserver startup. Providers should extract 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. + +## Synapse's Default 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). |