Two factor auth with IdentityServer3 - remember browser

Question

I'm implementing 2fa with IdentityServer3 + Asp.Net Identity (2.2.1). I'm stuck on the 2fa implementation. I've looked at the "AspNetIdentity_2fa" sample, which helped a lot.

I have everything wired up, except for the cookie that indicates the browser has been successfully authenticated. I can set the cookie during the code confirmation, but I cannot get to the cookie in the PostAuthenticateLocalAsync() call to see whether or not to take the 2fa path.

        protected override Task<AuthenticateResult> PostAuthenticateLocalAsync(User user, SignInMessage message)
    {
        if (user.TwoFactorEnabled) // && !TwoFactorCookieSet...
        {
            return Task.FromResult(new AuthenticateResult("/auth/sendcode", user.Id, user.DisplayName));
        }

        return base.PostAuthenticateLocalAsync(user, message);
    }

I believe I'm taking the correct approach in using the partial logins, but how would I detect that the current browser has already been approved?

More detail: the /auth/sendcode is the standard Asp.Net Identity pages/flow for 2fa, combined with the partial login logic from the sample.

Answer 1

Okay, I found that OwinEnvironmentService can be injected into IdentityServer services. I can get the cookies via OwinEnvironmentService. I'd be interested to hear any opinions on this solution (this isn't meant to be production-ready, it's just a concept):

internal class UserService : AspNetIdentityUserService<User, string>
{
    private readonly OwinEnvironmentService _owinEnvironmentService;

    public UserService(UserManager userMgr, OwinEnvironmentService owinEnvironmentService) : base(userMgr)
    {
        _owinEnvironmentService = owinEnvironmentService;
        DisplayNameClaimType = IdentityServer3.Core.Constants.ClaimTypes.Name;
    }

    protected override Task<AuthenticateResult> PostAuthenticateLocalAsync(User user, SignInMessage message)
    {
        if (user.TwoFactorEnabled)
        {
            var twoFactorNeeded = false;
            object httpContext;

            if (_owinEnvironmentService.Environment.TryGetValue("System.Web.HttpContextBase", out httpContext))
            {
                var cookies = (httpContext as HttpContext)?.Request.Cookies;
                if (cookies != null && !cookies.AllKeys.Contains(IdentityConstants.CookieNames.TwoFactorCompleted)) twoFactorNeeded = true;
            }

            if (twoFactorNeeded)
                return Task.FromResult(new AuthenticateResult("/auth/sendcode", user.Id, user.DisplayName));
        }

        return base.PostAuthenticateLocalAsync(user, message);
    }
}

UPDATED

Based on Brock's comment, I think I have a better solution.

// custom User Service
internal class UserService : AspNetIdentityUserService<User, string>
{
    private readonly OwinEnvironmentService _owinEnvironmentService;

    public UserService(UserManager userMgr, OwinEnvironmentService owinEnvironmentService) : base(userMgr)
    {
        _owinEnvironmentService = owinEnvironmentService;
        DisplayNameClaimType = IdentityServer3.Core.Constants.ClaimTypes.Name;
    }

    protected override async Task<AuthenticateResult> PostAuthenticateLocalAsync(User user, SignInMessage message)
    {
        if (user.TwoFactorEnabled)
        {
            var owinContext = new OwinContext(_owinEnvironmentService.Environment);
            var result = await owinContext.Authentication.AuthenticateAsync(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);
            if(result == null) return new AuthenticateResult("/auth/sendcode", user.Id, user.DisplayName);
        }

        return await base.PostAuthenticateLocalAsync(user, message);
    }
}

// (in MVC controller) generate the 2FA security code and send it
public async Task<ActionResult> SendCode(SendCodeViewModel model)
{
    // ...some code removed for brevity...

    var token = await UserManager.GenerateTwoFactorTokenAsync(userId, model.SelectedProvider);
    var identityResult = await UserManager.NotifyTwoFactorTokenAsync(userId, model.SelectedProvider, token);
    if (!identityResult.Succeeded) return View("Error");

    return RedirectToAction("VerifyCode", new { Provider = model.SelectedProvider, model.ReturnUrl, model.RememberMe });
}

// (in MVC controller) verify the code and sign in with 2FA
public async Task<ActionResult> VerifyCode(VerifyCodeViewModel model)
{
    // ...some code removed for brevity...

    var signInManager = new SignInManager<User, string>(UserManager, Request.GetOwinContext().Authentication);
    if (await UserManager.VerifyTwoFactorTokenAsync(user.Id, model.Provider, model.Code))
    {
        await UserManager.ResetAccessFailedCountAsync(user.Id);
        await signInManager.SignInAsync(user, model.RememberMe, model.RememberBrowser);
        var resumeUrl = await env.GetPartialLoginResumeUrlAsync();
        return Redirect(resumeUrl);
    }
    else
    {
        await UserManager.AccessFailedAsync(user.Id);
        ModelState.AddModelError("", "Invalid code.");
        return View(model);
    }
}