Fix critical and high security issues

- exec_script: relay now enforces admin role before forwarding to agent
- relay CORS: restrict allow_origins via ALLOWED_ORIGINS env var (docker-compose passes app URL)
- session-code: replace Math.random() with crypto.randomInt, add per-key rate limit (10 req/min)
- sessions GET: fix IDOR — users can only read their own sessions (admins see all)
- signal API: validate session ownership on create; enforce ownerUserId on all subsequent actions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/api/agent/session-code/route.ts

@@ -2,16 +2,34 @@ import { db } from '@/lib/db'
 import { machines, sessionCodes } from '@/lib/db/schema'
 import { eq, and } from 'drizzle-orm'
 import { NextRequest, NextResponse } from 'next/server'
+import { randomInt } from 'crypto'
 
 function generateSessionCode(): string {
   const chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789'
   let code = ''
   for (let i = 0; i < 6; i++) {
-    code += chars.charAt(Math.floor(Math.random() * chars.length))
+    code += chars.charAt(randomInt(chars.length))
   }
   return code
 }
 
+// Simple in-process rate limiter: max 10 requests per minute per access key
+const rateLimitMap = new Map<string, { count: number; resetAt: number }>()
+const RATE_LIMIT = 10
+const RATE_WINDOW_MS = 60_000
+
+function isRateLimited(key: string): boolean {
+  const now = Date.now()
+  const entry = rateLimitMap.get(key)
+  if (!entry || now >= entry.resetAt) {
+    rateLimitMap.set(key, { count: 1, resetAt: now + RATE_WINDOW_MS })
+    return false
+  }
+  if (entry.count >= RATE_LIMIT) return true
+  entry.count++
+  return false
+}
+
 export async function POST(request: NextRequest) {
   try {
     const { accessKey } = await request.json()
@@ -20,6 +38,10 @@ export async function POST(request: NextRequest) {
       return NextResponse.json({ error: 'Access key required' }, { status: 400 })
     }
 
+    if (isRateLimited(accessKey)) {
+      return NextResponse.json({ error: 'Too many requests' }, { status: 429 })
+    }
+
     const machineResult = await db
       .select()
       .from(machines)

app/api/sessions/[id]/route.ts

@@ -8,17 +8,22 @@ export async function GET(
   _request: NextRequest,
   { params }: { params: Promise<{ id: string }> }
 ) {
-  const session = await auth()
+  const authSession = await auth()
-  if (!session?.user?.id) {
+  if (!authSession?.user?.id) {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
   const { id } = await params
+  const isAdmin = (authSession.user as { role?: string }).role === 'admin'
 
   const result = await db
     .select()
     .from(sessions)
-    .where(eq(sessions.id, id))
+    .where(
+      isAdmin
+        ? eq(sessions.id, id)
+        : and(eq(sessions.id, id), eq(sessions.viewerUserId, authSession.user.id))
+    )
     .limit(1)
 
   if (!result[0]) {
@@ -32,8 +37,8 @@ export async function PATCH(
   request: NextRequest,
   { params }: { params: Promise<{ id: string }> }
 ) {
-  const session = await auth()
+  const authSession = await auth()
-  if (!session?.user?.id) {
+  if (!authSession?.user?.id) {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
@@ -47,7 +52,7 @@ export async function PATCH(
   await db
     .update(sessions)
     .set(updates)
-    .where(and(eq(sessions.id, id), eq(sessions.viewerUserId, session.user.id)))
+    .where(and(eq(sessions.id, id), eq(sessions.viewerUserId, authSession.user.id)))
 
   return NextResponse.json({ success: true })
 }

app/api/signal/route.ts

@@ -1,4 +1,7 @@
 import { auth } from '@/auth'
+import { db } from '@/lib/db'
+import { sessions } from '@/lib/db/schema'
+import { and, eq } from 'drizzle-orm'
 import { NextRequest, NextResponse } from 'next/server'
 
 // In-memory signaling store (use Redis for multi-instance deployments)
@@ -8,6 +11,7 @@ const signalingStore = new Map<string, {
   viewerCandidates: RTCIceCandidateInit[]
   hostCandidates: RTCIceCandidateInit[]
   createdAt: number
+  ownerUserId: string
 }>()
 
 function cleanupOldSessions() {
@@ -19,48 +23,59 @@ function cleanupOldSessions() {
 
 export async function POST(request: NextRequest) {
   try {
-    const session = await auth()
+    const authSession = await auth()
-    if (!session?.user) {
+    if (!authSession?.user?.id) {
       return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
     }
 
+    const userId = authSession.user.id
     const { action, sessionId, data } = await request.json()
     cleanupOldSessions()
 
     switch (action) {
-      case 'create-session':
+      case 'create-session': {
-        signalingStore.set(sessionId, { viewerCandidates: [], hostCandidates: [], createdAt: Date.now() })
+        // Verify the sessionId corresponds to a real session owned by this user
+        const dbSession = await db
+          .select({ id: sessions.id })
+          .from(sessions)
+          .where(and(eq(sessions.id, sessionId), eq(sessions.viewerUserId, userId)))
+          .limit(1)
+        if (!dbSession[0]) {
+          return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        }
+        signalingStore.set(sessionId, { viewerCandidates: [], hostCandidates: [], createdAt: Date.now(), ownerUserId: userId })
         return NextResponse.json({ success: true })
+      }
 
       case 'send-offer': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         s.offer = data.offer
         return NextResponse.json({ success: true })
       }
 
       case 'get-offer': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         return NextResponse.json({ offer: s.offer ?? null })
       }
 
       case 'send-answer': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         s.answer = data.answer
         return NextResponse.json({ success: true })
       }
 
       case 'get-answer': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         return NextResponse.json({ answer: s.answer ?? null })
       }
 
       case 'send-ice-candidate': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         if (data.role === 'viewer') s.viewerCandidates.push(data.candidate)
         else s.hostCandidates.push(data.candidate)
         return NextResponse.json({ success: true })
@@ -68,16 +83,19 @@ export async function POST(request: NextRequest) {
 
       case 'get-ice-candidates': {
         const s = signalingStore.get(sessionId)
-        if (!s) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
+        if (!s || s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         const candidates = data.role === 'viewer' ? s.hostCandidates : s.viewerCandidates
         if (data.role === 'viewer') s.hostCandidates = []
         else s.viewerCandidates = []
         return NextResponse.json({ candidates })
       }
 
-      case 'close-session':
+      case 'close-session': {
+        const s = signalingStore.get(sessionId)
+        if (s && s.ownerUserId !== userId) return NextResponse.json({ error: 'Session not found' }, { status: 404 })
         signalingStore.delete(sessionId)
         return NextResponse.json({ success: true })
+      }
 
       default:
         return NextResponse.json({ error: 'Unknown action' }, { status: 400 })

docker-compose.yml

@@ -52,6 +52,7 @@ services:
       - "8765:8765"
     environment:
       DATABASE_URL: postgresql://${POSTGRES_USER:-remotelink}:${POSTGRES_PASSWORD}@postgres:5432/${POSTGRES_DB:-remotelink}
+      ALLOWED_ORIGINS: ${NEXT_PUBLIC_APP_URL:-http://localhost:3000}
     depends_on:
       postgres:
         condition: service_healthy

relay/main.py

@@ -22,6 +22,8 @@ logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(mess
 log = logging.getLogger("relay")
 
 DATABASE_URL = os.environ["DATABASE_URL"]
+# Comma-separated list of allowed origins for CORS, e.g. "https://app.example.com"
+ALLOWED_ORIGINS = [o.strip() for o in os.environ.get("ALLOWED_ORIGINS", "").split(",") if o.strip()]
 
 # ── In-memory connection registry ────────────────────────────────────────────
 # machine_id (str) → WebSocket
@@ -30,6 +32,8 @@ agents: dict[str, WebSocket] = {}
 viewers: dict[str, WebSocket] = {}
 # session_id → machine_id
 session_to_machine: dict[str, str] = {}
+# session_id → viewer's user role ("admin" | "user")
+viewer_roles: dict[str, str] = {}
 
 db_pool: Optional[asyncpg.Pool] = None
 
@@ -47,7 +51,7 @@ app = FastAPI(lifespan=lifespan)
 
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["*"],
+    allow_origins=ALLOWED_ORIGINS if ALLOWED_ORIGINS else ["*"],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],
@@ -68,9 +72,10 @@ async def validate_agent(machine_id: str, access_key: str) -> Optional[dict]:
 async def validate_viewer(session_id: str, viewer_token: str) -> Optional[dict]:
     async with db_pool.acquire() as conn:
         row = await conn.fetchrow(
-            """SELECT id, machine_id, machine_name
+            """SELECT s.id, s.machine_id, s.machine_name, COALESCE(u.role, 'user') AS viewer_role
-               FROM sessions
+               FROM sessions s
-               WHERE id = $1 AND viewer_token = $2 AND ended_at IS NULL""",
+               LEFT JOIN users u ON u.id = s.viewer_user_id
+               WHERE s.id = $1 AND s.viewer_token = $2 AND s.ended_at IS NULL""",
             session_id, viewer_token,
         )
     return dict(row) if row else None
@@ -174,10 +179,13 @@ async def viewer_endpoint(
         await websocket.close(code=4002, reason="No machine associated with session")
         return
 
+    viewer_role = session.get("viewer_role", "user")
+
     await websocket.accept()
     viewers[session_id] = websocket
     session_to_machine[session_id] = machine_id
-    log.info(f"Viewer connected to session {session_id} (machine {machine_id})")
+    viewer_roles[session_id] = viewer_role
+    log.info(f"Viewer connected to session {session_id} (machine {machine_id}, role {viewer_role})")
 
     if machine_id in agents:
         # Tell agent to start streaming for this session
@@ -195,6 +203,14 @@ async def viewer_endpoint(
             try:
                 event = json.loads(text)
                 event["session_id"] = session_id
+                # exec_script is restricted to admin viewers only
+                if event.get("type") == "exec_script":
+                    if viewer_roles.get(session_id) != "admin":
+                        await send_json(websocket, {
+                            "type": "error",
+                            "message": "exec_script requires admin role",
+                        })
+                        continue
                 # Forward control events to the agent
                 if machine_id in agents:
                     await send_json(agents[machine_id], event)
@@ -207,6 +223,7 @@ async def viewer_endpoint(
     finally:
         viewers.pop(session_id, None)
         session_to_machine.pop(session_id, None)
+        viewer_roles.pop(session_id, None)
         if machine_id in agents:
             await send_json(agents[machine_id], {"type": "stop_stream", "session_id": session_id})
         log.info(f"Viewer disconnected from session {session_id}")