fix(api): harden ratelimit, SSRF, uploads and DM guards (#2074)

fluxer_api/src/api/channel/services/AttachmentUploadService.ts

@@ -233,11 +233,14 @@ export class AttachmentUploadService {
 				const parts = await Promise.all(
 					Array.from({length: partCount}, async (_, index) => {
 						const partNumber = index + 1;
+						const partContentLength =
+							partNumber < partCount ? partSize : attachment.file_size - partSize * (partCount - 1);
 						const presigned_upload_url = await this.storageService.getPresignedUploadPartURL({
 							bucket,
 							key: uploadKey,
 							uploadId,
 							partNumber,
+							contentLength: partContentLength,
 						});
 						const upload_url = applyUploadRelayDecision({
 							presignedUrl: presigned_upload_url,
@@ -246,7 +249,7 @@ export class AttachmentUploadService {
 							relayDecision: uploadRelayDecision,
 							uploadId,
 							partNumber,
-							maxBytes: partSize,
+							maxBytes: partContentLength,
 						});
 						return {part_number: partNumber, upload_url};
 					}),
@@ -275,7 +278,7 @@ export class AttachmentUploadService {
 		if (!Config.presignedAttachmentUploadsEnabled) {
 			throw new FeatureTemporarilyDisabledError();
 		}
-		await this.getUploadPermissionAndLimit({userId, channelId});
+		const {maxFileSize} = await this.getUploadPermissionAndLimit({userId, channelId});
 		const bucket = Config.s3.buckets.uploads;
 		return Promise.all(
 			uploads.map(async ({upload_filename, upload_id}, index) => {
@@ -305,6 +308,13 @@ export class AttachmentUploadService {
 						.catch(() => undefined);
 					throw InputValidationError.fromCode('parts', ValidationErrorCodes.NO_UPLOADED_PARTS_TO_FINALIZE);
 				}
+				const totalUploadedBytes = parts.reduce((sum, part) => sum + (part.size ?? 0), 0);
+				if (totalUploadedBytes > maxFileSize) {
+					await this.storageService
+						.abortMultipartUpload({bucket, key: upload_filename, uploadId: upload_id})
+						.catch(() => undefined);
+					throw new FileSizeTooLargeError(maxFileSize);
+				}
 				try {
 					await runAttachmentStorageOperation(() =>
 						this.storageService.completeMultipartUpload({

fluxer_api/src/api/channel/services/DMPermissionValidator.ts

@@ -40,9 +40,8 @@ export class DMPermissionValidator {
 		if (isBugHunterBotUser(senderUser)) {
 			return;
 		}
-		if (!senderUser.isBot && (senderUser.flags & UserFlags.SPAMMER) === UserFlags.SPAMMER) {
-			return;
-		}
+		const isShadowbannedSpammer =
+			!senderUser.isBot && (senderUser.flags & UserFlags.SPAMMER) === UserFlags.SPAMMER;
 		const [senderBlockedTarget, targetBlockedSender, areFriends, targetSettings, senderSettings] = await Promise.all([
 			this.deps.userRepository.getRelationship(senderId, recipientId, RelationshipTypes.BLOCKED),
 			this.deps.userRepository.getRelationship(recipientId, senderId, RelationshipTypes.BLOCKED),
@@ -53,6 +52,9 @@ export class DMPermissionValidator {
 		if (senderBlockedTarget || targetBlockedSender) {
 			throw new CannotSendMessagesToUserError();
 		}
+		if (isShadowbannedSpammer) {
+			return;
+		}
 		if (areFriends) {
 			return;
 		}

fluxer_api/src/api/download/DownloadService.ts

@@ -51,6 +51,7 @@ function isUnsatisfiableRangeError(error: unknown): boolean {
 }
 const DESKTOP_BUCKET_PREFIX = 'desktop';
 const DESKTOP_TEST_BUCKET_PREFIX = 'desktop-test';
+const DOWNLOAD_KEY_ALLOWED_PREFIXES = [`${DESKTOP_BUCKET_PREFIX}/`, `${DESKTOP_TEST_BUCKET_PREFIX}/`];
 const DEFAULT_API_CLIENT_BASE_URL = 'https://api.fluxer.app';
 const GITHUB_RELEASE_DOWNLOAD_BASE_URL = 'https://github.com/fluxerapp/fluxer/releases/download';
 const GITHUB_RELEASE_MARKER_DIRECTORY = 'github-releases';
@@ -987,7 +988,13 @@ export class DownloadService {
 				return null;
 			}
 		}
-		return normalized.length > 0 ? normalized : null;
+		if (normalized.length === 0) {
+			return null;
+		}
+		if (!DOWNLOAD_KEY_ALLOWED_PREFIXES.some((prefix) => normalized.startsWith(prefix))) {
+			return null;
+		}
+		return normalized;
 	}
 
 	private normalizePlatformArchKey(key: string): string | null {

fluxer_api/src/api/infrastructure/IStorageService.ts

@@ -91,6 +91,7 @@ export interface IStorageService {
 		key: string;
 		uploadId: string;
 		partNumber: number;
+		contentLength?: number;
 		expiresIn?: number;
 	}): Promise<string>;
 	purgeBucket(bucket: string): Promise<void>;

fluxer_api/src/api/infrastructure/StorageService.ts

@@ -296,12 +296,14 @@ export class StorageService implements IStorageService {
 		key,
 		uploadId,
 		partNumber,
+		contentLength,
 		expiresIn = seconds('1 hour'),
 	}: {
 		bucket: string;
 		key: string;
 		uploadId: string;
 		partNumber: number;
+		contentLength?: number;
 		expiresIn?: number;
 	}): Promise<string> {
 		const command = new UploadPartCommand({
@@ -309,6 +311,7 @@ export class StorageService implements IStorageService {
 			Key: key,
 			UploadId: uploadId,
 			PartNumber: partNumber,
+			ContentLength: contentLength,
 		});
 		return getSignedUrl(this.presignClient, command, {expiresIn});
 	}

fluxer_api/src/api/middleware/RateLimitMiddleware.ts

@@ -52,7 +52,11 @@ function shouldShowHeadersOnSuccess(accountType: AccountType): boolean {
 function getClientIdentifier(ctx: Context<HonoEnv>): string {
 	const user = ctx.get('user');
 	if (user?.id) {
-		return `user:${user.id}`;
+		const tokenType = ctx.get('authTokenType') ?? 'session';
+		if (tokenType === 'bearer') {
+			return `user:${user.id}:bearer:${ctx.get('oauthBearerApplicationId') ?? 'unknown'}`;
+		}
+		return `user:${user.id}:${tokenType}`;
 	}
 	const ip = extractClientIp(ctx.req.raw, {
 		trustClientIpHeader: Config.proxy.trust_client_ip_header,

fluxer_api/src/api/user/services/UserAccountLookupService.ts

@@ -89,14 +89,17 @@ export class UserAccountLookupService {
 		let guildMember: GuildMemberResponse | null = null;
 		let guildMemberDomain: GuildMember | null = null;
 		if (guildId != null) {
-			guildMemberDomain = await this.deps.guildRepository.getMember(guildId, targetId);
-			if (guildMemberDomain) {
-				guildMember = await this.deps.guildService.members.getMember({
-					userId,
-					targetId,
-					guildId,
-					requestCache,
-				});
+			const viewerMember = await this.deps.guildRepository.getMember(guildId, userId);
+			if (viewerMember) {
+				guildMemberDomain = await this.deps.guildRepository.getMember(guildId, targetId);
+				if (guildMemberDomain) {
+					guildMember = await this.deps.guildService.members.getMember({
+						userId,
+						targetId,
+						guildId,
+						requestCache,
+					});
+				}
 			}
 		}
 		let premiumType = user.premiumType ?? undefined;

fluxer_api/src/api/user/services/UserRelationshipService.ts

@@ -118,15 +118,17 @@ export class UserRelationshipService {
 		userCacheService: UserCacheService;
 		requestCache: RequestCache;
 	}): Promise<Relationship> {
-		if (!staffForceAccept && (await getInstanceConfigRepository().getInstancePolicyConfig()).direct_messages_disabled) {
+		const requesterUser = await this.userRepository.findUnique(userId);
+		const requesterIsStaff =
+			requesterUser != null && (requesterUser.flags & UserFlags.STAFF) === UserFlags.STAFF;
+		if (
+			!requesterIsStaff &&
+			(await getInstanceConfigRepository().getInstancePolicyConfig()).direct_messages_disabled
+		) {
 			throw new DirectMessagesDisabledError();
 		}
-		const requesterUser = await this.userRepository.findUnique(userId);
-		if (staffForceAccept) {
-			const requesterIsStaff = requesterUser != null && (requesterUser.flags & UserFlags.STAFF) === UserFlags.STAFF;
-			if (requesterIsStaff) {
-				return await this.forceCreateFriendship({userId, targetId, userCacheService, requestCache});
-			}
+		if (staffForceAccept && requesterIsStaff) {
+			return await this.forceCreateFriendship({userId, targetId, userCacheService, requestCache});
 		}
 		if (!requesterUser) {
 			throw new UnknownUserError();