I have JWT-based claims authentication/ authorization set up in my .NET Core application, which authenticates as expected, but my policy enforcement is not acting as I would expect.
I have a requirements implementation and handler set up as follows:
public class ImpersonationRequirement : IAuthorizationRequirement
{
}
public class ImpersonationHandler : AuthorizationHandler<ImpersonationRequirement>
{
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context,
ImpersonationRequirement requirement)
{
if (context.User.CanImpersonate()) context.Succeed(requirement);
return Task.CompletedTask;
}
}
I have a helper set up like so:
public static bool CanImpersonate(
this ClaimsPrincipal principal)
{
var val = principal?.FindFirst(MyClaimTypes.CAN_IMPERSONATE)?.Value;
return bool.TryParse(val, out var value) && value;
}
public class MyClaimTypes
{
/// <summary>
/// Boolean value indicating this user is authorized to impersonate other customer accounts.
/// </summary>
public const string CAN_IMPERSONATE = "cim";
...
/// <summary>
/// Actual name of the user impersonating the current user.
/// </summary>
public const string IMPERSONATING_USER = "imp";
}
...off of my Startup.cs, I have the policy defined:
services.AddAuthorization(options =>
{
options.AddPolicy("Impersonator", policy => policy.Requirements.Add(new ImpersonationRequirement()));
});
...and on my controller, it's written as such:
[Produces("application/json")]
[Authorize(Policy = "Impersonator")]
public class ImpersonationController : Controller
{
private readonly ILogger _logger;
private readonly ITokenManagementService _tokenManagementService;
private readonly UserManager<MyUser> _userManager;
public ImpersonationController(ITokenManagementService tokenManagementService, ILoggerFactory loggerFactory, UserManager<MyUser> userManager)
{
_tokenManagementService = tokenManagementService;
_userManager = userManager;
_logger = loggerFactory.CreateLogger<ImpersonationController>();
}
[HttpPost]
[Route("~/api/impersonation/token")]
[ProducesResponseType(typeof(AuthenticationResponse), 200)]
[ProducesResponseType(typeof(Exception), 500)]
public async Task<IActionResult> Impersonate([FromBody] string userNameToImpersonate)
{
try
{
var impersonated = await _userManager.FindByNameAsync(userNameToImpersonate);
if (impersonated == null) throw new EntityNotFoundException($"Unable to find user '{userNameToImpersonate}' in the data store.");
var actualUserId = User.UserId();
var token = await _tokenManagementService.GenerateJwt(impersonated.Id, actualUserId);
var refresh = await _tokenManagementService.GenerateRefreshToken(impersonated.Id, actualUserId);
var response = new AuthenticationResponse {AuthenticationToken = token, RefreshToken = refresh};
return Ok(response);
}
catch (Exception ex)
{
return new OopsResult(ex);
}
}
}
If I run this with the AuthorizeAttribute commented out, I can take a look at the user's claims, and the "cim: true" is in the claims enumeration, but if I run it with the AuthorizeAttribute enabled, I get a 403 Forbidden error.
I tried putting a breakpoint on the line in the ImpersonationHandler:
if (context.User.CanImpersonate()) context.Succeed(requirement);
...but the debugger never stops here, so I don't know what the problem is. Can someone educate me as to what I'm doing wrong?
