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/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()
-    if (!session?.user) {
+    const authSession = await auth()
+    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':
-        signalingStore.set(sessionId, { viewerCandidates: [], hostCandidates: [], createdAt: Date.now() })
+      case 'create-session': {
+        // 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 })