From b68041df3dcbcf3ca04c500d1712aa22a3c2580c Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Mon, 2 Mar 2020 17:05:09 +0000 Subject: [PATCH] Add a whitelist for the SSO confirmation step. --- docs/sample_config.yaml | 22 +++++++++++++++++--- synapse/config/sso.py | 18 +++++++++++++++++ synapse/rest/client/v1/login.py | 26 ++++++++++++++++-------- tests/rest/client/v1/test_login.py | 32 +++++++++++++++++++++++++++--- 4 files changed, 84 insertions(+), 14 deletions(-) diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml index bbb8a4d93..f719ec696 100644 --- a/docs/sample_config.yaml +++ b/docs/sample_config.yaml @@ -1363,6 +1363,22 @@ saml2_config: # Additional settings to use with single-sign on systems such as SAML2 and CAS. # sso: + # A list of client URLs which are whitelisted so that the user does not + # have to confirm giving access to their account to the URL. Any client + # whose URL starts with an entry in the following list will not be subject + # to an additional confirmation step after the SSO login is completed. + # + # WARNING: An entry such as "https://my.client" is insecure, because it + # will also match "https://my.client.evil.site", exposing your users to + # phishing attacks from evil.site. To avoid this, include a slash after the + # hostname: "https://my.client/". + # + # By default, this list is empty. + # + #client_whitelist: + # - https://riot.im/develop + # - https://my.custom.client/ + # Directory in which Synapse will try to find the template files below. # If not set, default templates from within the Synapse package will be used. # @@ -1372,8 +1388,8 @@ sso: # # Synapse will look for the following templates in this directory: # - # * HTML page for confirmation of redirect during authentication: - # 'sso_redirect_confirm.html'. + # * HTML page for a confirmation step before redirecting back to the client + # with the login token: 'sso_redirect_confirm.html'. # # When rendering, this template is given three variables: # * redirect_url: the URL the user is about to be redirected to. Needs @@ -1381,7 +1397,7 @@ sso: # https://jinja.palletsprojects.com/en/2.11.x/templates/#html-escaping). # # * display_url: the same as `redirect_url`, but with the query - # parameters stripped. The intention is to have a + # parameters stripped. The intention is to have a # human-readable URL to show to users, not to use it as # the final address to redirect to. Needs manual escaping # (see https://jinja.palletsprojects.com/en/2.11.x/templates/#html-escaping). diff --git a/synapse/config/sso.py b/synapse/config/sso.py index f426b65b4..56299bd4e 100644 --- a/synapse/config/sso.py +++ b/synapse/config/sso.py @@ -37,11 +37,29 @@ class SSOConfig(Config): self.sso_redirect_confirm_template_dir = template_dir + self.sso_client_whitelist = sso_config.get("client_whitelist") or [] + def generate_config_section(self, **kwargs): return """\ # Additional settings to use with single-sign on systems such as SAML2 and CAS. # sso: + # A list of client URLs which are whitelisted so that the user does not + # have to confirm giving access to their account to the URL. Any client + # whose URL starts with an entry in the following list will not be subject + # to an additional confirmation step after the SSO login is completed. + # + # WARNING: An entry such as "https://my.client" is insecure, because it + # will also match "https://my.client.evil.site", exposing your users to + # phishing attacks from evil.site. To avoid this, include a slash after the + # hostname: "https://my.client/". + # + # By default, this list is empty. + # + #client_whitelist: + # - https://riot.im/develop + # - https://my.custom.client/ + # Directory in which Synapse will try to find the template files below. # If not set, default templates from within the Synapse package will be used. # diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py index 1acfd01d8..b2bc7537d 100644 --- a/synapse/rest/client/v1/login.py +++ b/synapse/rest/client/v1/login.py @@ -556,6 +556,9 @@ class SSOAuthHandler(object): self._server_name = hs.config.server_name + # cast to tuple for use with str.startswith + self._whitelisted_sso_clients = tuple(hs.config.sso_client_whitelist) + async def on_successful_auth( self, username, request, client_redirect_url, user_display_name=None ): @@ -605,11 +608,6 @@ class SSOAuthHandler(object): registered_user_id ) - # Remove the query parameters from the redirect URL to get a shorter version of - # it. This is only to display a human-readable URL in the template, but not the - # URL we redirect users to. - redirect_url_no_params = client_redirect_url.split("?")[0] - # Append the login token to the original redirect URL (i.e. with its query # parameters kept intact) to build the URL to which the template needs to # redirect the users once they have clicked on the confirmation link. @@ -617,17 +615,29 @@ class SSOAuthHandler(object): client_redirect_url, "loginToken", login_token ) - # Serve the redirect confirmation page + # if the client is whitelisted, we can redirect straight to it + if client_redirect_url.startswith(self._whitelisted_sso_clients): + request.redirect(redirect_url) + finish_request(request) + return + + # Otherwise, serve the redirect confirmation page. + + # Remove the query parameters from the redirect URL to get a shorter version of + # it. This is only to display a human-readable URL in the template, but not the + # URL we redirect users to. + redirect_url_no_params = client_redirect_url.split("?")[0] + html = self._template.render( display_url=redirect_url_no_params, redirect_url=redirect_url, server_name=self._server_name, - ) + ).encode("utf-8") request.setResponseCode(200) request.setHeader(b"Content-Type", b"text/html; charset=utf-8") request.setHeader(b"Content-Length", b"%d" % (len(html),)) - request.write(html.encode("utf8")) + request.write(html) finish_request(request) @staticmethod diff --git a/tests/rest/client/v1/test_login.py b/tests/rest/client/v1/test_login.py index 2b8ad5c75..da2c9bfa1 100644 --- a/tests/rest/client/v1/test_login.py +++ b/tests/rest/client/v1/test_login.py @@ -268,13 +268,11 @@ class CASRedirectConfirmTestCase(unittest.HomeserverTestCase): self.redirect_path = "_synapse/client/login/sso/redirect/confirm" config = self.default_config() - config["enable_registration"] = True config["cas_config"] = { "enabled": True, "server_url": "https://fake.test", "service_url": "https://matrix.goodserver.com:8448", } - config["public_baseurl"] = self.base_url async def get_raw(uri, args): """Return an example response payload from a call to the `/proxyValidate` @@ -310,7 +308,7 @@ class CASRedirectConfirmTestCase(unittest.HomeserverTestCase): """Tests that the SSO login flow serves a confirmation page before redirecting a user to the redirect URL. """ - base_url = "/login/cas/ticket?redirectUrl" + base_url = "/_matrix/client/r0/login/cas/ticket?redirectUrl" redirect_url = "https://dodgy-site.com/" url_parts = list(urllib.parse.urlparse(base_url)) @@ -325,6 +323,7 @@ class CASRedirectConfirmTestCase(unittest.HomeserverTestCase): self.render(request) # Test that the response is HTML. + self.assertEqual(channel.code, 200) content_type_header_value = "" for header in channel.result.get("headers", []): if header[0] == b"Content-Type": @@ -337,3 +336,30 @@ class CASRedirectConfirmTestCase(unittest.HomeserverTestCase): # And that it contains our redirect link self.assertIn(redirect_url, channel.result["body"].decode("UTF-8")) + + @override_config( + { + "sso": { + "client_whitelist": [ + "https://legit-site.com/", + "https://other-site.com/", + ] + } + } + ) + def test_cas_redirect_whitelisted(self): + """Tests that the SSO login flow serves a redirect to a whitelisted url + """ + redirect_url = "https://legit-site.com/" + cas_ticket_url = ( + "/_matrix/client/r0/login/cas/ticket?redirectUrl=%s&ticket=ticket" + % (urllib.parse.quote(redirect_url)) + ) + + # Get Synapse to call the fake CAS and serve the template. + request, channel = self.make_request("GET", cas_ticket_url) + self.render(request) + + self.assertEqual(channel.code, 302) + location_headers = channel.headers.getRawHeaders("Location") + self.assertEqual(location_headers[0][: len(redirect_url)], redirect_url)