fix(security): close Critical IDOR/authz gaps (C-1/C-2)

C-1: messaging endpoints now enforce channel participation (public
     channels open; private require channel_members). authorUserId is
     forced to the authenticated user (no more author spoofing); edit/
     delete require message-author ownership; history read gated too.
C-2: PUT /commands body strictly validated + size-capped via
     SyncCommandsDto (kills catalog poisoning / DoS). Optional
     FABRIC_BACKEND_GUILD_COMMANDS_SYNC_KEY restricts the write to the
     plugin when set; never weaker than before when unset.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/commands/commands.controller.ts

@@ -1,29 +1,51 @@
 import {
   Body,
   Controller,
+  ForbiddenException,
   Get,
+  Headers,
   Put,
   Req,
   UnauthorizedException,
 } from '@nestjs/common';
+import { timingSafeEqual } from 'node:crypto';
 import { CommandsService } from './commands.service.js';
+import { SyncCommandsDto } from './dto.sync-commands.dto.js';
 
 type AuthedRequest = { userId?: string };
 
+function safeEqual(a: string, b: string): boolean {
+  const ab = Buffer.from(a);
+  const bb = Buffer.from(b);
+  if (ab.length !== bb.length) return false;
+  return timingSafeEqual(ab, bb);
+}
+
 @Controller('commands')
 export class CommandsController {
   constructor(private readonly commands: CommandsService) {}
 
-  // Plugin syncs the OpenClaw native-command catalog here (any authenticated
-  // agent/user; idempotent full replace).
+  // Guild C-2: catalog write is privileged. When
+  // FABRIC_BACKEND_GUILD_COMMANDS_SYNC_KEY is configured (recommended in
+  // production), the caller must present a matching x-commands-sync-key
+  // header — this restricts writes to the OpenClaw plugin. When unset, we
+  // fall back to "any authenticated agent/user" (never weaker than before).
+  // The body is always strictly validated + size-capped via SyncCommandsDto.
   @Put()
   sync(
     @Req() req: AuthedRequest,
-    @Body() body: { commands?: unknown[] },
+    @Body() body: SyncCommandsDto,
+    @Headers('x-commands-sync-key') syncKey?: string,
   ) {
-    if (!req.userId) throw new UnauthorizedException('missing user');
-    const commands = Array.isArray(body?.commands) ? body.commands : [];
-    return this.commands.sync(commands);
+    const configured = process.env.FABRIC_BACKEND_GUILD_COMMANDS_SYNC_KEY ?? '';
+    if (configured) {
+      if (!syncKey || !safeEqual(syncKey, configured)) {
+        throw new ForbiddenException('invalid commands sync key');
+      }
+    } else if (!req.userId) {
+      throw new UnauthorizedException('missing user');
+    }
+    return this.commands.sync(body.commands as unknown[]);
   }
 
   // Frontend reads the catalog to drive `/` autocomplete.

src/commands/dto.sync-commands.dto.ts

@@ -0,0 +1,102 @@
+import {
+  ArrayMaxSize,
+  IsArray,
+  IsBoolean,
+  IsOptional,
+  IsString,
+  MaxLength,
+  ValidateNested,
+} from 'class-validator';
+import { Type } from 'class-transformer';
+
+// Guild C-2: the slash-command catalog is guild-global and rendered by the
+// frontend `/` autocomplete. Without a strict schema + caps a single
+// authenticated caller could poison it or blow up the DB / clients.
+// The global ValidationPipe runs with { whitelist, forbidNonWhitelisted },
+// so any unknown field is rejected.
+
+class CommandChoiceDto {
+  @IsString()
+  @MaxLength(200)
+  value!: string;
+
+  @IsString()
+  @MaxLength(200)
+  label!: string;
+}
+
+class CommandArgDto {
+  @IsString()
+  @MaxLength(100)
+  name!: string;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  description?: string;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(40)
+  type?: string;
+
+  @IsOptional()
+  @IsBoolean()
+  required?: boolean;
+
+  @IsOptional()
+  @IsBoolean()
+  captureRemaining?: boolean;
+
+  @IsOptional()
+  @IsBoolean()
+  preferAutocomplete?: boolean;
+
+  // null when there are no choices (plugin sends explicit null).
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(100)
+  @ValidateNested({ each: true })
+  @Type(() => CommandChoiceDto)
+  choices?: CommandChoiceDto[] | null;
+}
+
+class CommandSpecDto {
+  @IsString()
+  @MaxLength(100)
+  name!: string;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(100)
+  nativeName?: string;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  description?: string;
+
+  @IsOptional()
+  @IsBoolean()
+  acceptsArgs?: boolean;
+
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(50)
+  @ValidateNested({ each: true })
+  @Type(() => CommandArgDto)
+  args?: CommandArgDto[];
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  argsParsing?: string;
+}
+
+export class SyncCommandsDto {
+  @IsArray()
+  @ArrayMaxSize(200)
+  @ValidateNested({ each: true })
+  @Type(() => CommandSpecDto)
+  commands!: CommandSpecDto[];
+}

src/messaging/messaging.controller.ts

@@ -3,6 +3,7 @@ import {
   ConflictException,
   Controller,
   Delete,
+  ForbiddenException,
   Get,
   Headers,
   NotFoundException,
@@ -10,11 +11,13 @@ import {
   Patch,
   Post,
   Query,
+  Req,
 } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import { DataSource, Repository } from 'typeorm';
 import { CreateMessageDto } from './dto.create-message.dto.js';
 import { Channel } from '../entities/channel.entity.js';
+import { ChannelMember } from '../entities/channel-member.entity.js';
 import { Message } from '../entities/message.entity.js';
 import { IdempotencyRecord } from '../entities/idempotency-record.entity.js';
 import { WakeMapping } from '../entities/wake-mapping.entity.js';
@@ -36,6 +39,8 @@ export class MessagingController {
     private readonly dataSource: DataSource,
     @InjectRepository(Channel)
     private readonly channelRepo: Repository<Channel>,
+    @InjectRepository(ChannelMember)
+    private readonly memberRepo: Repository<ChannelMember>,
     @InjectRepository(Message)
     private readonly messageRepo: Repository<Message>,
     @InjectRepository(IdempotencyRecord)
@@ -86,6 +91,19 @@ export class MessagingController {
     };
   }
 
+  // Channel-participant gate (Guild C-1): public channels are readable/
+  // writable by any authenticated user; private channels require explicit
+  // channel_members membership. Returns the channel so callers can reuse it.
+  private async assertParticipant(channelId: string, userId: string): Promise<Channel> {
+    const channel = await this.channelRepo.findOne({ where: { id: channelId } });
+    if (!channel) throw new NotFoundException('channel not found');
+    if (channel.isPublic) return channel;
+    if (!userId) throw new ForbiddenException('not a channel member');
+    const member = await this.memberRepo.findOne({ where: { channelId, userId } });
+    if (!member) throw new ForbiddenException('not a channel member');
+    return channel;
+  }
+
   // Persists one message (allocates a seq under a channel row lock) and
   // returns its view. Used for normal messages and for guild /ack messages.
   private async persistMessage(
@@ -136,20 +154,25 @@ export class MessagingController {
   async create(
     @Param('id') channelId: string,
     @Body() body: CreateMessageDto,
+    @Req() req: { userId?: string },
     @Headers('idempotency-key') idempotencyKey?: string,
   ) {
     const scope = `POST:/channels/${channelId}/messages`;
     const existed = await this.getIdempotentResponse(scope, idempotencyKey);
     if (existed) return existed;
 
-    const channel = await this.channelRepo.findOne({ where: { id: channelId } });
-    if (!channel) throw new NotFoundException('channel not found');
+    // Guild C-1: caller must be a participant of the channel, and the
+    // author is always the authenticated user — body.authorUserId is
+    // ignored so a caller can never post as someone else.
+    const userId = String(req.userId ?? '');
+    if (!userId) throw new ForbiddenException('missing user');
+    const channel = await this.assertParticipant(channelId, userId);
     if (channel.closed) {
       throw new ConflictException({ error: 'channel_closed', message: 'channel is closed' });
     }
     const xType = channel.xType ?? 'general';
     const isRotating = xType === 'discuss' || xType === 'work';
-    const authorUserId = String(body.authorUserId ?? 'anonymous');
+    const authorUserId = userId;
 
     // ---- translate <@user.name:NAME> -> <@userId> (outside backticks) via
     // Center before anything else persists/parses the content
@@ -223,14 +246,23 @@ export class MessagingController {
     @Param('id') channelId: string,
     @Param('messageId') messageId: string,
     @Body() body: { content?: string },
+    @Req() req: { userId?: string },
     @Headers('idempotency-key') idempotencyKey?: string,
   ) {
     const scope = `PATCH:/channels/${channelId}/messages/${messageId}`;
     const existed = await this.getIdempotentResponse(scope, idempotencyKey);
     if (existed) return existed;
 
+    // Guild C-1: participant + author-ownership.
+    const userId = String(req.userId ?? '');
+    if (!userId) throw new ForbiddenException('missing user');
+    await this.assertParticipant(channelId, userId);
+
     const item = await this.messageRepo.findOne({ where: { channelId, messageId } });
     if (!item) return { status: 'not_found' };
+    if (item.authorUserId !== userId) {
+      throw new ForbiddenException('not the message author');
+    }
 
     const now = Date.now();
     const createdAt = new Date(item.createdAt).getTime();
@@ -259,14 +291,23 @@ export class MessagingController {
   async remove(
     @Param('id') channelId: string,
     @Param('messageId') messageId: string,
+    @Req() req: { userId?: string },
     @Headers('idempotency-key') idempotencyKey?: string,
   ) {
     const scope = `DELETE:/channels/${channelId}/messages/${messageId}`;
     const existed = await this.getIdempotentResponse(scope, idempotencyKey);
     if (existed) return existed;
 
+    // Guild C-1: participant + author-ownership.
+    const userId = String(req.userId ?? '');
+    if (!userId) throw new ForbiddenException('missing user');
+    await this.assertParticipant(channelId, userId);
+
     const item = await this.messageRepo.findOne({ where: { channelId, messageId } });
     if (!item) return { status: 'not_found' };
+    if (item.authorUserId !== userId) {
+      throw new ForbiddenException('not the message author');
+    }
 
     item.isDeleted = true;
     item.deletedAt = new Date();
@@ -304,10 +345,14 @@ export class MessagingController {
   @Get()
   async listBySeq(
     @Param('id') channelId: string,
+    @Req() req: { userId?: string },
     @Query('seq_from') seqFrom?: string,
     @Query('seq_to') seqTo?: string,
     @Query('limit') limit?: string,
   ) {
+    // Guild C-1: only participants may read channel history.
+    const userId = String(req.userId ?? '');
+    if (!userId) throw new ForbiddenException('missing user');
     const from = seqFrom ? Number(seqFrom) : 1;
     const to = seqTo ? Number(seqTo) : Number.MAX_SAFE_INTEGER;
     const safeLimit = clampLimit(limit, DEFAULT_PAGE_LIMIT, MAX_PAGE_LIMIT);
@@ -327,10 +372,7 @@ export class MessagingController {
       };
     }
 
-    const channel = await this.channelRepo.findOne({ where: { id: channelId } });
-    if (!channel) {
-      throw new NotFoundException('channel not found');
-    }
+    const channel = await this.assertParticipant(channelId, userId);
 
     const qb = this.messageRepo
       .createQueryBuilder('m')

src/messaging/messaging.module.ts

@@ -2,12 +2,13 @@ import { Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { MessagingController } from './messaging.controller.js';
 import { Channel } from '../entities/channel.entity.js';
+import { ChannelMember } from '../entities/channel-member.entity.js';
 import { Message } from '../entities/message.entity.js';
 import { IdempotencyRecord } from '../entities/idempotency-record.entity.js';
 import { WakeMapping } from '../entities/wake-mapping.entity.js';
 
 @Module({
-  imports: [TypeOrmModule.forFeature([Channel, Message, IdempotencyRecord, WakeMapping])],
+  imports: [TypeOrmModule.forFeature([Channel, ChannelMember, Message, IdempotencyRecord, WakeMapping])],
   controllers: [MessagingController],
 })
 export class MessagingModule {}