After weeks of research on Identity 2.0, impersonation, delegation and Kerberos, I am still unable to find a solution that will allow me to impersonate the ClaimsIdentity user I have created using OWIN in my MVC application. The specifics to my scenario are as follows.
Windows Authentication is disabled + Anonymous enabled.
I am using an OWIN startup class to manually authenticate the user against our Active Directory. Then I pack up some of the properties into a cookie which is available throughout the rest of the application. This is the link I referenced when setting up these classes.
Startup.Auth.cs
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
AuthenticationType = MyAuthentication.ApplicationCookie,
LoginPath = new PathString("/Login"),
Provider = new CookieAuthenticationProvider(),
CookieName = "SessionName",
CookieHttpOnly = true,
ExpireTimeSpan = TimeSpan.FromHours(double.Parse(ConfigurationManager.AppSettings["CookieLength"]))
});
AuthenticationService.cs
using System;
using System.DirectoryServices.AccountManagement;
using System.DirectoryServices;
using System.Security.Claims;
using Microsoft.Owin.Security;
using System.Configuration;
using System.Collections.Generic;
using System.Linq;
namespace mine.Security
{
public class AuthenticationService
{
private readonly IAuthenticationManager _authenticationManager;
private PrincipalContext _context;
private UserPrincipal _userPrincipal;
private ClaimsIdentity _identity;
public AuthenticationService(IAuthenticationManager authenticationManager)
{
_authenticationManager = authenticationManager;
}
/// <summary>
/// Check if username and password matches existing account in AD.
/// </summary>
/// <param name="username"></param>
/// <param name="password"></param>
/// <returns></returns>
public AuthenticationResult SignIn(String username, String password)
{
// connect to active directory
_context = new PrincipalContext(ContextType.Domain,
ConfigurationManager.ConnectionStrings["LdapServer"].ConnectionString,
ConfigurationManager.ConnectionStrings["LdapContainer"].ConnectionString,
ContextOptions.SimpleBind,
ConfigurationManager.ConnectionStrings["LDAPUser"].ConnectionString,
ConfigurationManager.ConnectionStrings["LDAPPass"].ConnectionString);
// try to find if the user exists
_userPrincipal = UserPrincipal.FindByIdentity(_context, IdentityType.SamAccountName, username);
if (_userPrincipal == null)
{
return new AuthenticationResult("There was an issue authenticating you.");
}
// try to validate credentials
if (!_context.ValidateCredentials(username, password))
{
return new AuthenticationResult("Incorrect username/password combination.");
}
// ensure account is not locked out
if (_userPrincipal.IsAccountLockedOut())
{
return new AuthenticationResult("There was an issue authenticating you.");
}
// ensure account is enabled
if (_userPrincipal.Enabled.HasValue && _userPrincipal.Enabled.Value == false)
{
return new AuthenticationResult("There was an issue authenticating you.");
}
MyContext dbcontext = new MyContext();
var appUser = dbcontext.AppUsers.Where(a => a.ActiveDirectoryLogin.ToLower() == "domain\\" +_userPrincipal.SamAccountName.ToLower()).FirstOrDefault();
if (appUser == null)
{
return new AuthenticationResult("Sorry, you have not been granted user access to the MED application.");
}
// pass both adprincipal and appuser model to build claims identity
_identity = CreateIdentity(_userPrincipal, appUser);
_authenticationManager.SignOut(MyAuthentication.ApplicationCookie);
_authenticationManager.SignIn(new AuthenticationProperties() { IsPersistent = false }, _identity);
return new AuthenticationResult();
}
/// <summary>
/// Creates identity and packages into cookie
/// </summary>
/// <param name="userPrincipal"></param>
/// <returns></returns>
private ClaimsIdentity CreateIdentity(UserPrincipal userPrincipal, AppUser appUser)
{
var identity = new ClaimsIdentity(MyAuthentication.ApplicationCookie, ClaimsIdentity.DefaultNameClaimType, ClaimsIdentity.DefaultRoleClaimType);
identity.AddClaim(new Claim("http://schemas.microsoft.com/accesscontrolservice/2010/07/claims/identityprovider", "Active Directory"));
identity.AddClaim(new Claim(ClaimTypes.GivenName, userPrincipal.GivenName));
identity.AddClaim(new Claim(ClaimTypes.Surname, userPrincipal.Surname));
identity.AddClaim(new Claim(ClaimTypes.NameIdentifier, userPrincipal.SamAccountName));
identity.AddClaim(new Claim(ClaimTypes.Name, userPrincipal.SamAccountName));
identity.AddClaim(new Claim(ClaimTypes.Upn, userPrincipal.UserPrincipalName));
if (!String.IsNullOrEmpty(userPrincipal.EmailAddress))
{
identity.AddClaim(new Claim(ClaimTypes.Email, userPrincipal.EmailAddress));
}
// db claims
if (appUser.DefaultAppOfficeId != null)
{
identity.AddClaim(new Claim("DefaultOffice", appUser.AppOffice.OfficeName));
}
if (appUser.CurrentAppOfficeId != null)
{
identity.AddClaim(new Claim("Office", appUser.AppOffice1.OfficeName));
}
var claims = new List<Claim>();
DirectoryEntry dirEntry = (DirectoryEntry)userPrincipal.GetUnderlyingObject();
foreach (string groupDn in dirEntry.Properties["memberOf"])
{
string[] parts = groupDn.Replace("CN=", "").Split(',');
claims.Add(new Claim(ClaimTypes.Role, parts[0]));
}
if (claims.Count > 0)
{
identity.AddClaims(claims);
}
return identity;
}
/// <summary>
/// Authentication result class
/// </summary>
public class AuthenticationResult
{
public AuthenticationResult(string errorMessage = null)
{
ErrorMessage = errorMessage;
}
public String ErrorMessage { get; private set; }
public Boolean IsSuccess => String.IsNullOrEmpty(ErrorMessage);
}
}
}
That part seems to work just fine. However, I am required to be able to impersonate the ClaimsIdentity when making calls to the database because the database has role level security setup on it. I need the connection to be done under the context of the ClaimsIdentity for the remainder of that user's session.
Can someone help point me towards an example where I am able to impersonate the ClaimsIdentity object when making the database queries to the SQL Server database?
[SOLVED Update 2-1-19] I have written a blog post detailing this process and it is available here.
I was able to accomplish this by doing the following. I created a class to make these methods reusable. In that class i used the System.IdentityModel.Selectors and System.IdentityModel.Tokens library to generate a KeberosReceiverSecurityToken and stored it in memory.
public class KerberosTokenCacher
{
public KerberosTokenCacher()
{
}
public KerberosReceiverSecurityToken WriteToCache(string contextUsername, string contextPassword)
{
KerberosSecurityTokenProvider provider =
new KerberosSecurityTokenProvider("YOURSPN",
TokenImpersonationLevel.Impersonation,
new NetworkCredential(contextUsername.ToLower(), contextPassword, "yourdomain"));
KerberosRequestorSecurityToken requestorToken = provider.GetToken(TimeSpan.FromMinutes(double.Parse(ConfigurationManager.AppSettings["KerberosTokenExpiration"]))) as KerberosRequestorSecurityToken;
KerberosReceiverSecurityToken receiverToken = new KerberosReceiverSecurityToken(requestorToken.GetRequest());
IAppCache appCache = new CachingService();
KerberosReceiverSecurityToken tokenFactory() => receiverToken;
return appCache.GetOrAdd(contextUsername.ToLower(), tokenFactory); // this will either add the token or get the token if it exists
}
public KerberosReceiverSecurityToken ReadFromCache(string contextUsername)
{
IAppCache appCache = new CachingService();
KerberosReceiverSecurityToken token = appCache.Get<KerberosReceiverSecurityToken>(contextUsername.ToLower());
return token;
}
public void DeleteFromCache(string contextUsername)
{
IAppCache appCache = new CachingService();
KerberosReceiverSecurityToken token = appCache.Get<KerberosReceiverSecurityToken>(contextUsername.ToLower());
if(token != null)
{
appCache.Remove(contextUsername.ToLower());
}
}
}
Now when users login using my AuthenticationService, I create the ticket and store it in memory. When they log out I do the reverse and remove the ticket from cache. The final part (which i am still looking for a better way to accomplish this), I added some code to the constructor of my dbcontext class.
public MyContext(bool impersonate = true): base("name=MyContext")
{
if (impersonate)
{
var currentUsername = HttpContext.Current.GetOwinContext().Authentication.User?.Identity?.Name;
if (!string.IsNullOrEmpty(currentUsername)){
KerberosTokenCacher kerberosTokenCacher = new KerberosTokenCacher();
KerberosReceiverSecurityToken token = kerberosTokenCacher.ReadFromCache(currentUsername);
if (token != null)
{
token.WindowsIdentity.Impersonate();
}
else
{
// token has expired or cache has expired so you must log in again
HttpContext.Current.Response.Redirect("Login/Logoff");
}
}
}
}
Obviously its definitely not perfect, but it allows me to use Owin Cookie Authentication against active directory and have a Kerberos ticket generated allowing the connection to the SQL database to be under the context of the user who was authenticated.