File 0007-PAOS-Do-not-populate-Destination-attribute... of Package lasso

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File 0007-PAOS-Do-not-populate-Destination-attribute.patch of Package lasso (Revision 5cd4b227a3ca5896fcc6a2f40d95ad3c)

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From 1e85f1b2bd30c0d93b4a2ef37b35abeae3d15b56 Mon Sep 17 00:00:00 2001
From: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>
Date: Fri, 28 Jun 2019 02:36:19 +0300
Subject: [PATCH] PAOS: Do not populate "Destination" attribute

When ECP profile (saml-ecp-v2.0-cs01) is used with PAOS binding Lasso
populates an AuthnRequest with the "Destination" attribute set to
AssertionConsumerURL of an SP - this leads to IdP-side errors because
the destination attribute in the request does not match the IdP URL.

The "Destination" attribute is mandatory only for HTTP Redirect and HTTP
Post bindings when AuthRequests are signed per saml-bindings-2.0-os
(sections 3.4.5.2 and 3.5.5.2). Specifically for PAOS it makes sense to
avoid setting that optional attribute because an ECP decides which IdP
to use, not the SP.

Fixes Bug: 34409
License: MIT
Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>
---
 lasso/saml-2.0/login.c   | 18 +++++++++---------
 lasso/saml-2.0/profile.c | 10 +++++++++-
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/lasso/saml-2.0/login.c b/lasso/saml-2.0/login.c
index 6e8f7553..0d4bb1da 100644
--- a/lasso/saml-2.0/login.c
+++ b/lasso/saml-2.0/login.c
@@ -222,7 +222,7 @@ _lasso_login_must_verify_signature(LassoProfile *profile) {
 gint
 lasso_saml20_login_build_authn_request_msg(LassoLogin *login)
 {
-	char *url = NULL;
+	char *assertionConsumerServiceURL = NULL;
 	gboolean must_sign = TRUE;
 	LassoProfile *profile;
 	LassoSamlp2AuthnRequest *authn_request;
@@ -247,29 +247,29 @@ lasso_saml20_login_build_authn_request_msg(LassoLogin *login)
 	}
 
 	if (login->http_method == LASSO_HTTP_METHOD_PAOS) {
-
 		/*
 		 * PAOS is special, the url passed to build_request is the
 		 * AssertionConsumerServiceURL of this SP, not the
-		 * destination.
+		 * destination IdP URL. This is done to fill paos:responseConsumerURL
+		 * appropriately down the line in build_request_msg.
+		 * See https://dev.entrouvert.org/issues/34409 for more information.
 		 */
 		if (authn_request->AssertionConsumerServiceURL) {
-			url = authn_request->AssertionConsumerServiceURL;
+			assertionConsumerServiceURL = authn_request->AssertionConsumerServiceURL;
 			if (!lasso_saml20_provider_check_assertion_consumer_service_url(
-					LASSO_PROVIDER(profile->server), url, LASSO_SAML2_METADATA_BINDING_PAOS)) {
+					LASSO_PROVIDER(profile->server), assertionConsumerServiceURL, LASSO_SAML2_METADATA_BINDING_PAOS)) {
 				rc = LASSO_PROFILE_ERROR_INVALID_REQUEST;
 				goto cleanup;
 			}
 		} else {
-			url = lasso_saml20_provider_get_assertion_consumer_service_url_by_binding(
+			assertionConsumerServiceURL = lasso_saml20_provider_get_assertion_consumer_service_url_by_binding(
 					LASSO_PROVIDER(profile->server), LASSO_SAML2_METADATA_BINDING_PAOS);
-			lasso_assign_new_string(authn_request->AssertionConsumerServiceURL, url);
+			lasso_assign_new_string(authn_request->AssertionConsumerServiceURL, assertionConsumerServiceURL);
 		}
 	}
 
-
 	lasso_check_good_rc(lasso_saml20_profile_build_request_msg(profile, "SingleSignOnService",
-				login->http_method, url));
+				login->http_method, assertionConsumerServiceURL));
 
 cleanup:
 	return rc;
diff --git a/lasso/saml-2.0/profile.c b/lasso/saml-2.0/profile.c
index 22a4e08c..85f535ae 100644
--- a/lasso/saml-2.0/profile.c
+++ b/lasso/saml-2.0/profile.c
@@ -968,7 +968,15 @@ lasso_saml20_profile_build_request_msg(LassoProfile *profile, const char *servic
 		made_url = url = get_url(provider, service, http_method_to_binding(method));
 	}
 
-	if (url) {
+
+	// Usage of the Destination attribute on a request is mandated only
+	// in "3.4.5.2" and "3.5.5.2" in saml-bindings-2.0-os for signed requests
+	// and is marked as optional in the XSD schema otherwise.
+	// PAOS is a special case because an SP does not select an IdP - ECP does
+	// it instead. Therefore, this attribute needs to be left unpopulated.
+	if (method == LASSO_HTTP_METHOD_PAOS) {
+		lasso_release_string(((LassoSamlp2RequestAbstract*)profile->request)->Destination);
+	} else if (url) {
 		lasso_assign_string(((LassoSamlp2RequestAbstract*)profile->request)->Destination,
 				url);
 	} else {
-- 
2.21.0

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File 0007-PAOS-Do-not-populate-Destination-attribute.patch of Package lasso (Revision 5cd4b227a3ca5896fcc6a2f40d95ad3c)

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