Return SAML error response and relay state back to service provider when SAML authentication failure occurs

[mefarazath]

Description:
Right now we are showing the error notification page. It is great if we can redirect to relying party with the response and relay state. If the application cannot handle error response, there could be a configuration (could be at Service Provider level, or could be system wide) and if someone set that to false, then we can show error in our notification page.

Affected Product Version:
5.3.0

[isharak]

Thank you for your contribution!
We are closing this issue since it has not been prioritized for a long time. Chances are that it has already been solved in more recent versions. If not, we will be re-evaluating this when it becomes a priority.

[rksk]

Currently, all SAML (inbound) related errors are redirected to a common error page on IS via a SAML response [1]. However, this common page does not parse the specific error message included in the SAML response and simply displays a generic error message.

Two improvements are expected here:

• A configuration flag to determine whether the SAML error should be sent back to the Relying Party or redirected to the common error page on IS.
• The common error page on IS should be updated to display meaningful error messages, similar to how it currently handles OAuth2/OIDC errors.

[1] https://github.com/wso2-extensions/identity-inbound-auth-saml/blob/dd4ceb12243c14d95fe8eee30693a79d5cb281a6/components/org.wso2.carbon.identity.sso.saml/src/main/java/org/wso2/carbon/identity/sso/saml/servlet/SAMLSSOProviderServlet.java#L594