Redirecting Users from Unauthorized Page - asp.net-mvc

Question

I have an MVC application that I recently converted the authentication/authorization method from forms to federated. Everything works fine, but on the home page I have to create a cookie for the authorization of the rest of my site to work properly. When users navigate to the home page first it works great, if they navigate to a different page first where authorization is required they get a 401 unauthorized error page.
When I had the forms authentication implemented it would redirect users that were unauthorized to the login page, with federation I no longer have a login page so I would like to redirect to the home page. With forms authentication the redirection was automatic, how would I setup something similar for my federated application?
Here are the federated portions of my web.config that are relevant. Again, federated authentication/authorization works, just the unauthorized redirect that isn't.
<system.web>
<customErrors mode="Off"/>
<authentication mode="None"/>
<authorization>
<deny users="?"/>
</authorization>
<membership defaultProvider="ADMembershipProvider">
<providers>
<add name="ADMembershipProvider" type="System.Web.Security.ActiveDirectoryMembershipProvider" connectionProtection="Secure" attributeMapUsername="sAMAccountName" connectionStringName="ADConn" connectionUsername="UName" connectionPassword="Pass" />
</providers>
</membership>
<roleManager enabled="true" defaultProvider="ActiveDirectoryRoleProvider" cacheRolesInCookie="true" cookieName=".ADLibraryROLES" cookiePath="/" cookieTimeout="1440" cookieRequireSSL="false" cookieSlidingExpiration="true" createPersistentCookie="true" cookieProtection="All">
<providers>
<clear />
<add name="ActiveDirectoryRoleProvider" connectionStringName="ADConn" connectionUsername="UName" connectionPassword="Pass" attributeMapUsername="sAMAccountName" type="MyApp.ActiveDirectoryRoleProvider" />
</providers>
</roleManager>
</system.web>
<system.webServer>
<modules>
<add name="WSFederationAuthenticationModule" type="System.IdentityModel.Services.WSFederationAuthenticationModule, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="managedHandler"/>
<add name="SessionAuthenticationModule" type="System.IdentityModel.Services.SessionAuthenticationModule, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="managedHandler"/>
</modules>
</system.webServer>
<system.identityModel>
<identityConfiguration>
<audienceUris>
<add value="https://fed.example.com/"/>
</audienceUris>
<securityTokenHandlers>
<add type="System.IdentityModel.Services.Tokens.MachineKeySessionSecurityTokenHandler, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
<remove type="System.IdentityModel.Tokens.SessionSecurityTokenHandler, System.IdentityModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
</securityTokenHandlers>
<certificateValidation certificateValidationMode="None"/>
<issuerNameRegistry type="System.IdentityModel.Tokens.ValidatingIssuerNameRegistry, System.IdentityModel.Tokens.ValidatingIssuerNameRegistry">
<authority name="http://myfedservice.example.com/adfs/services/trust">
<keys>
<add thumbprint="mythumb"/>
</keys>
<validIssuers>
<add name="http://fed.example.com/adfs/services/trust"/>
</validIssuers>
</authority>
</issuerNameRegistry>
</identityConfiguration>
</system.identityModel>
<system.identityModel.services>
<federationConfiguration>
<cookieHandler requireSsl="true"/>
<wsFederation passiveRedirectEnabled="true" issuer="https://fed.example.com/adfs/ls/" realm="https://fed.example.com/" reply="https://fed.example.com/" requireHttps="true" persistentCookiesOnPassiveRedirects="true"/>
</federationConfiguration>
</system.identityModel.services>

Answer 1

You can configure this in the wsFederation section, see MSDN for further details. By setting the “passiveRedirectEnabled” to true, the WSFederationAuthenticationModule will look at all outgoing responses, trying to find HTTP 401s. If it finds a 401, it will modify the response and turn it into a redirect to the STS. Please note that in production you want to change requireHttps to true.
<system.identityModel.services>
<federationConfiguration>
<wsFederation passiveRedirectEnabled="true"
issuer="http://localhost:15839/wsFederationSTS/Issue"
realm="http://localhost:50969/" reply="http://localhost:50969/"
requireHttps="false"
signOutReply="http://localhost:50969/SignedOutPage.html"
signOutQueryString="Param1=value2&Param2=value2"
persistentCookiesOnPassiveRedirects="true" />
<cookieHandler requireSsl="false" />
</federationConfiguration>
Please note that you also need to add these modules:
<modules>
<add name="WSFederationAuthenticationModule" type="System.IdentityModel.Services.WSFederationAuthenticationModule, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="managedHandler" />
<add name="SessionAuthenticationModule" type="System.IdentityModel.Services.SessionAuthenticationModule, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="managedHandler" />
</modules>
and the following config sections:
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="system.identityModel" type="System.IdentityModel.Configuration.SystemIdentityModelSection, System.IdentityModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
<section name="system.identityModel.services" type="System.IdentityModel.Services.Configuration.SystemIdentityModelServicesSection, System.IdentityModel.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />