From 2704f4feaae4a1d800f01e3854781347ce62c4a2 Mon Sep 17 00:00:00 2001
From: Benjamin Dauvergne <bdauvergne@entrouvert.com>
Date: Tue, 3 Aug 2021 16:38:02 +0200
Subject: [PATCH] views: keep a nonce during a forceAuthn request (#55953)

Nonce value and forceAuthn is linked to the request id which is randomly
generated by lasso and returned by IdPs as part of a SAML SSO.
---
 mellon/views.py       | 11 ++++++++++-
 tests/test_sso_slo.py | 20 +++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/mellon/views.py b/mellon/views.py
index a22be3d..c78c517 100644
--- a/mellon/views.py
+++ b/mellon/views.py
@@ -251,6 +251,11 @@ class LoginView(ProfileMixin, LogMixin, View):
                     if content is not None:
                         values.append(content)
         attributes['issuer'] = login.remoteProviderId
+        in_response_to = login.response.inResponseTo
+        if in_response_to:
+            attributes['nonce'] = request.session.get('mellon-nonce-%s' % in_response_to)
+            attributes['force_authn'] = request.session.get('mellon-force-authn-%s' % in_response_to, False)
+
         if login.nameIdentifier:
             name_id = login.nameIdentifier
             name_id_format = force_text(name_id.format or lasso.SAML2_NAME_IDENTIFIER_FORMAT_UNSPECIFIED)
@@ -490,8 +495,12 @@ class LoginView(ProfileMixin, LogMixin, View):
             policy = authn_request.nameIdPolicy
             policy.allowCreate = utils.get_setting(idp, 'NAME_ID_POLICY_ALLOW_CREATE')
             policy.format = utils.get_setting(idp, 'NAME_ID_POLICY_FORMAT')
-            force_authn = utils.get_setting(idp, 'FORCE_AUTHN')
+            force_authn = utils.get_setting(idp, 'FORCE_AUTHN') or 'force-authn' in request.GET
+            # link the nonce and forceAuthn state to the request-id
+            if 'nonce' in request.GET:
+                request.session['mellon-nonce-%s' % authn_request.id] = request.GET['nonce']
             if force_authn:
+                request.session['mellon-force-authn-%s' % authn_request.id] = True
                 authn_request.forceAuthn = True
             if request.GET.get('passive') == '1':
                 authn_request.isPassive = True
diff --git a/tests/test_sso_slo.py b/tests/test_sso_slo.py
index f9ec6b1..61eae22 100644
--- a/tests/test_sso_slo.py
+++ b/tests/test_sso_slo.py
@@ -94,7 +94,7 @@ class MockIdp(object):
         self.session_dump = None
 
     def process_authn_request_redirect(self, url, auth_result=True, consent=True, msg=None):
-        login = lasso.Login(self.server)
+        login = self.login = lasso.Login(self.server)
         if self.identity_dump:
             login.setIdentityFromDump(self.identity_dump)
         if self.session_dump:
@@ -421,6 +421,8 @@ def test_sso(db, app, idp, caplog, sp_settings):
     assert app.session['mellon_session']['first_name'] == ['<i>Fr\xe9d\xe9ric</i>']
     assert app.session['mellon_session']['email'] == ['john.doe@gmail.com']
     assert app.session['mellon_session']['wtf'] == []
+    assert not app.session['mellon_session']['force_authn']
+    assert not app.session['mellon_session']['nonce']
 
 
 def test_sso_request_denied(db, app, idp, caplog, sp_settings):
@@ -732,3 +734,19 @@ def test_debug_sso(db, app, idp, caplog, sp_settings, settings):
     assert '<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"' in response_text
     assert '<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"' in response_text
     assert 'mellon: created new user _' in response_text
+
+
+def test_nonce(db, app, idp, caplog, sp_settings):
+    response = app.get(reverse('mellon_login') + '?nonce=1234')
+    url, body, relay_state = idp.process_authn_request_redirect(response['Location'])
+    response = app.post(reverse('mellon_login'), params={'SAMLResponse': body, 'RelayState': relay_state})
+    assert app.session['mellon_session']['nonce'] == '1234'
+
+
+def test_force_authn(db, app, idp, caplog, sp_settings):
+    response = app.get(reverse('mellon_login') + '?force-authn=1')
+    url, body, relay_state = idp.process_authn_request_redirect(response['Location'])
+    assert idp.login.request.forceAuthn
+
+    response = app.post(reverse('mellon_login'), params={'SAMLResponse': body, 'RelayState': relay_state})
+    assert app.session['mellon_session']['force_authn']
-- 
2.32.0.rc0