Split authentication and authorization

Iceshrimp.Backend/Controllers/AuthController.cs

@@ -1,4 +1,3 @@
-using System.Net;
 using System.Net.Mime;
 using Iceshrimp.Backend.Controllers.Schemas;
 using Iceshrimp.Backend.Core.Database;
@@ -19,16 +18,15 @@ namespace Iceshrimp.Backend.Controllers;
 [Route("/api/iceshrimp/v1/auth")]
 public class AuthController(DatabaseContext db, UserService userSvc) : Controller {
 	[HttpGet]
-	[Authentication(false)]
+	[Authenticate]
 	[ProducesResponseType(StatusCodes.Status200OK, Type = typeof(AuthResponse))]
 	public IActionResult GetAuthStatus() {
 		var session = Request.HttpContext.GetSession();
 
-		if (session == null) {
+		if (session == null)
 			return Ok(new AuthResponse {
 				Status = AuthStatusEnum.Guest
 			});
-		}
 
 		return Ok(new AuthResponse {
 			Status = session.Active ? AuthStatusEnum.Authenticated : AuthStatusEnum.TwoFactor,

Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs

@@ -39,6 +39,7 @@ public static class ServiceExtensions {
 		services.AddSingleton<QueueService>();
 		services.AddSingleton<ErrorHandlerMiddleware>();
 		services.AddSingleton<RequestBufferingMiddleware>();
+		services.AddSingleton<AuthorizationMiddleware>();
 
 		// Hosted services = long running background tasks
 		// Note: These need to be added as a singleton as well to ensure data consistency

Iceshrimp.Backend/Core/Extensions/WebApplicationExtensions.cs

@@ -12,6 +12,7 @@ public static class WebApplicationExtensions {
 		return app.UseMiddleware<ErrorHandlerMiddleware>()
 		          .UseMiddleware<RequestBufferingMiddleware>()
 		          .UseMiddleware<AuthenticationMiddleware>()
+		          .UseMiddleware<AuthorizationMiddleware>()
 		          .UseMiddleware<AuthorizedFetchMiddleware>();
 	}
 

Iceshrimp.Backend/Core/Middleware/AuthenticationMiddleware.cs

@@ -1,4 +1,3 @@
-using System.Diagnostics.CodeAnalysis;
 using Iceshrimp.Backend.Core.Database;
 using Iceshrimp.Backend.Core.Database.Tables;
 using Microsoft.AspNetCore.Http.Features;
@@ -6,20 +5,15 @@ using Microsoft.EntityFrameworkCore;
 
 namespace Iceshrimp.Backend.Core.Middleware;
 
-public class AuthenticationMiddleware(
-	[SuppressMessage("ReSharper", "SuggestBaseTypeForParameterInConstructor")]
-	DatabaseContext db
-) : IMiddleware {
+public class AuthenticationMiddleware(DatabaseContext db) : IMiddleware {
 	public async Task InvokeAsync(HttpContext ctx, RequestDelegate next) {
 		var endpoint  = ctx.Features.Get<IEndpointFeature>()?.Endpoint;
-		var attribute = endpoint?.Metadata.GetMetadata<AuthenticationAttribute>();
+		var attribute = endpoint?.Metadata.GetMetadata<AuthenticateAttribute>();
 
 		if (attribute != null) {
 			var request = ctx.Request;
 			var header  = request.Headers.Authorization.ToString();
 			if (!header.ToLowerInvariant().StartsWith("bearer ")) {
-				if (attribute.Required)
-					throw GracefulException.Unauthorized("Missing bearer token in authorization header");
 				await next(ctx);
 				return;
 			}
@@ -27,11 +21,10 @@ public class AuthenticationMiddleware(
 			var token   = header[7..];
 			var session = await db.Sessions.Include(p => p.User).FirstOrDefaultAsync(p => p.Token == token);
 			if (session == null) {
-				if (attribute.Required)
-					throw GracefulException.Forbidden("Bearer token is invalid");
 				await next(ctx);
 				return;
 			}
+
 			ctx.SetSession(session);
 		}
 
@@ -39,9 +32,7 @@ public class AuthenticationMiddleware(
 	}
 }
 
-public class AuthenticationAttribute(bool required = true) : Attribute {
-	public bool Required { get; } = required;
-}
+public class AuthenticateAttribute : Attribute;
 
 public static class HttpContextExtensions {
 	private const string Key = "session";
@@ -49,7 +40,7 @@ public static class HttpContextExtensions {
 	internal static void SetSession(this HttpContext ctx, Session session) {
 		ctx.Items.Add(Key, session);
 	}
-	
+
 	public static Session? GetSession(this HttpContext ctx) {
 		ctx.Items.TryGetValue(Key, out var session);
 		return session as Session;

Iceshrimp.Backend/Core/Middleware/AuthorizationMiddleware.cs

@@ -0,0 +1,18 @@
+using Microsoft.AspNetCore.Http.Features;
+
+namespace Iceshrimp.Backend.Core.Middleware;
+
+public class AuthorizationMiddleware : IMiddleware {
+	public async Task InvokeAsync(HttpContext ctx, RequestDelegate next) {
+		var endpoint  = ctx.Features.Get<IEndpointFeature>()?.Endpoint;
+		var attribute = endpoint?.Metadata.GetMetadata<AuthorizeAttribute>();
+
+		if (attribute != null)
+			if (ctx.GetSession() is not { Active: true })
+				throw GracefulException.Forbidden("This method requires an authenticated user");
+
+		await next(ctx);
+	}
+}
+
+public class AuthorizeAttribute : Attribute;

Iceshrimp.Backend/Core/Middleware/ErrorHandlerMiddleware.cs

@@ -77,7 +77,7 @@ public class GracefulException(HttpStatusCode statusCode, string error, string m
 	public static GracefulException Forbidden(string message, string? details = null) {
 		return new GracefulException(HttpStatusCode.Forbidden, message, details);
 	}
-	
+
 	public static GracefulException Unauthorized(string message, string? details = null) {
 		return new GracefulException(HttpStatusCode.Unauthorized, message, details);
 	}