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zachmargolis
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Jun 14, 2017
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LGTM! Thanks for the fix
**Why**: A bug was discovered where an OIDC Service Provider's configuration included attributes that are only meant for SAML, namely `assertion_consumer_logout_service_url`. That attribute was set to an empty string, but the logic in `SingleLogoutHandler#slo_not_implemented_at_sp?` was checking for `nil?` only, which caused `SamlIdpController#logout` to proceed all the way to call `generate_slo_request` with a nil URL (instead of returning early at `finish_slo_at_idp`), which resulted in an exception in `SecureHeadersWhitelister.extract_domain` due to the `nil` URL. **How**: In addition to the empty SAML attribute, reproducing this bug also requires that the user have an active identity with the OIDC SP. In SAML, identities get deactivated during the logout process, but OIDC identities remain active (which could be another bug). This is why the spec signs the user in fully to the SP first to create the identity, then signs out, then signs in again, but cancels the sign in process on the 2FA screen. Using `blank?` instead of `nil?` fixes the bug.
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Why: A bug was discovered where an OIDC Service Provider's
configuration included attributes that are only meant for SAML,
namely
assertion_consumer_logout_service_url. That attribute wasset to an empty string, but the logic in
SingleLogoutHandler#slo_not_implemented_at_sp?was checking fornil?only, which causedSamlIdpController#logoutto proceed all theway to call
generate_slo_requestwith a nil URL (instead ofreturning early at
finish_slo_at_idp), which resulted in anexception in
SecureHeadersWhitelister.extract_domaindue to thenilURL.
How: In addition to the empty SAML attribute, reproducing this bug
also requires that the user have an active identity with the OIDC SP.
In SAML, identities get deactivated during the logout process, but
OIDC identities remain active (which could be another bug).
This is why the spec signs the user in fully to the SP first to create
the identity, then signs out, then signs in again, but cancels the
sign in process on the 2FA screen.
Using
blank?instead ofnil?fixes the bug.