ASP.NET Core JWT mapping role claims to ClaimsIdentity

Question

I want to protect ASP.NET Core Web API using JWT. Additionally, I would like to have an option of using roles from tokens payload directly in controller actions attributes.

Now, while I did find it out how to use it with Policies:

Authorize(Policy="CheckIfUserIsOfRoleX")
ControllerAction()...

I would like better to have an option to use something usual like:

Authorize(Role="RoleX")

where Role would be automatically mapped from JWT payload.

{
    name: "somename",
    roles: ["RoleX", "RoleY", "RoleZ"]
}

So, what is the easiest way to accomplish this in ASP.NET Core? Is there a way to get this working automatically through some settings/mappings (if so, where to set it?) or should I, after token is validated, intercept generation of ClaimsIdentity and add roles claims manually (if so, where/how to do that?)?

trinvh trinvh · Accepted Answer · 2017-02-04T07:09:27

You need get valid claims when generating JWT. Here is example code:

Login logic:

[HttpPost]
[AllowAnonymous]
public async Task<IActionResult> Login([FromBody] ApplicationUser applicationUser) {
    var result = await _signInManager.PasswordSignInAsync(applicationUser.UserName, applicationUser.Password, true, false);
    if(result.Succeeded) {
        var user = await _userManager.FindByNameAsync(applicationUser.UserName);

        // Get valid claims and pass them into JWT
        var claims = await GetValidClaims(user);

        // Create the JWT security token and encode it.
        var jwt = new JwtSecurityToken(
            issuer: _jwtOptions.Issuer,
            audience: _jwtOptions.Audience,
            claims: claims,
            notBefore: _jwtOptions.NotBefore,
            expires: _jwtOptions.Expiration,
            signingCredentials: _jwtOptions.SigningCredentials);
        //...
    } else {
        throw new ApiException('Wrong username or password', 403);
    }
}

Get user claims based UserRoles, RoleClaims and UserClaims tables (ASP.NET Identity):

private async Task<List<Claim>> GetValidClaims(ApplicationUser user)
{
    IdentityOptions _options = new IdentityOptions();
    var claims = new List<Claim>
        {
            new Claim(JwtRegisteredClaimNames.Sub, user.UserName),
            new Claim(JwtRegisteredClaimNames.Jti, await _jwtOptions.JtiGenerator()),
            new Claim(JwtRegisteredClaimNames.Iat, ToUnixEpochDate(_jwtOptions.IssuedAt).ToString(), ClaimValueTypes.Integer64),
            new Claim(_options.ClaimsIdentity.UserIdClaimType, user.Id.ToString()),
            new Claim(_options.ClaimsIdentity.UserNameClaimType, user.UserName)
        };
    var userClaims = await _userManager.GetClaimsAsync(user);
    var userRoles = await _userManager.GetRolesAsync(user);
    claims.AddRange(userClaims);
    foreach (var userRole in userRoles)
    {
        claims.Add(new Claim(ClaimTypes.Role, userRole));
        var role = await _roleManager.FindByNameAsync(userRole);
        if(role != null)
        {
            var roleClaims = await _roleManager.GetClaimsAsync(role);
            foreach(Claim roleClaim in roleClaims)
            {
                claims.Add(roleClaim);
            }
        }
    }
    return claims;
}

In Startup.cs please add needed policies into authorization:

void ConfigureServices(IServiceCollection service) {
   services.AddAuthorization(options =>
    {
        // Here I stored necessary permissions/roles in a constant
        foreach (var prop in typeof(ClaimPermission).GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy))
        {
            options.AddPolicy(prop.GetValue(null).ToString(), policy => policy.RequireClaim(ClaimType.Permission, prop.GetValue(null).ToString()));
        }
    });
}

ClaimPermission:

public static class ClaimPermission
{
    public const string
        CanAddNewService = "Tự thêm dịch vụ",
        CanCancelCustomerServices = "Hủy dịch vụ khách gọi",
        CanPrintReceiptAgain = "In lại hóa đơn",
        CanImportGoods = "Quản lý tồn kho",
        CanManageComputers = "Quản lý máy tính",
        CanManageCoffees = "Quản lý bàn cà phê",
        CanManageBillards = "Quản lý bàn billard";
}

Use the similar snippet to get all pre-defined permissions and insert it to asp.net permission claims table:

var staffRole = await roleManager.CreateRoleIfNotExists(UserType.Staff);

foreach (var prop in typeof(ClaimPermission).GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy))
{
    await roleManager.AddClaimIfNotExists(staffRole, prop.GetValue(null).ToString());
}

I am a beginner in ASP.NET, so please let me know if you have better solutions.

And, I don't know how worst when I put all claims/permissions into JWT. Too long? Performance ? Should I store generated JWT in database and check it later for getting valid user's roles/claims?

ASP.NET Core JWT mapping role claims to ClaimsIdentity

3 Answers