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SECURITYSPEC.md

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AgentPaaS Security Specification

Overview

AgentPaaS is a multi-tenant Agent Platform as a Service. Security is critical because:

  • Multiple tenants share the same infrastructure
  • Agents execute arbitrary LLM-generated code via tools
  • API keys and secrets must be protected at rest and in transit
  • WeChat/external channel integrations handle user credentials

Threat Model

External Attacker         Malicious Tenant         Compromised Agent
      |                        |                        |
      v                        v                        v
  [API Gateway]           [Tenant Boundary]        [Sandbox]
  - Auth bypass            - Data leakage           - Code injection
  - CORS abuse             - Quota bypass           - Resource exhaustion
  - Rate limit bypass      - Privilege escalation   - Secret exfiltration
  - Input injection        - SQL injection          - Subprocess escape

Security Architecture

1. Authentication & Authorization

API Key Authentication:

  • Keys generated with secrets.token_hex(16) (128-bit entropy)
  • Keys hashed before storage (MUST use salted PBKDF2, not bare SHA-256)
  • Bearer token in Authorization header
  • Key prefix stored for identification without exposing full key

RBAC (Role-Based Access Control):

Role Permissions
Admin tenants:*, agents:*, keys:*, billing:read, secrets:*, admin:*
Developer agents:read/write/execute, keys:read/write, runs:read, secrets:read
Viewer agents:read, runs:read, billing:read

Requirements:

  • All endpoints MUST require authentication (including admin endpoints)
  • Scope checks MUST be enforced at handler level
  • Failed auth attempts MUST be logged with source IP

2. Tenant Isolation

  • All database queries MUST include tenant_id filter via parameterized queries
  • NEVER use string interpolation for SQL (no f-strings, no .format())
  • Agent execution contexts MUST be isolated per tenant
  • Secrets MUST NOT leak across tenant boundaries

3. Secrets Management

Encryption:

  • AES-256-GCM via cryptography library (MUST NOT fall back to base64)
  • Master key MUST be provided via AGENTPAAS_MASTER_KEY environment variable
  • Master key MUST NOT be auto-generated at runtime in production

Injection:

  • Secrets SHOULD be injected via execution Context, NOT environment variables
  • Secrets MUST NOT appear in logs, error messages, or API responses

4. Input Validation

  • All API inputs MUST have size limits (max_length on string fields)
  • Agent configs MUST be validated against schema before compilation
  • SQL LIKE queries MUST escape wildcards (%, _)
  • User input to agents MUST be size-limited (default: 100KB)

5. Sandbox & Execution

  • Agent execution MUST run in isolated sandbox (L0/L1/L2)
  • Input data MUST be passed via JSON file, NOT string interpolation in code
  • Resource limits (CPU, memory, time) MUST be enforced
  • Subprocess creation MUST be explicitly allowed per policy

5b. ToolGateway — Runtime Tool Permission Enforcement

Implementation: lambdagent/tool_gateway.py (2026-03-28)

All tool calls pass through GatedTool before execution. This closes the gap where guard.dangerousCommandBlock and guard.highRiskConfirmation were declared in YAML configs but had zero runtime effect.

How it works in the PaaS context:

  1. Tenant deploys agent with guard config via POST /api/v1/agents
  2. On POST /api/v1/agents/{id}/run, compiler calls build_agent(config)
  3. build_agent() reads guard → creates ToolGateway(GatewayPolicy.from_guard_config(...))
  4. Every Tool in the agent is wrapped as GatedTool
  5. Each tool call is classified (SAFE → CRITICAL), checked against policy, and audited

Risk classification (5 levels, 50+ regex patterns):

Level Action when dangerousCommandBlock: true
CRITICAL Always BLOCK (e.g., rm -rf /, curl\|sh, credential access)
HIGH BLOCK, or CONFIRM if highRiskConfirmation: true (e.g., sudo, rm -r, pip install)
MEDIUM LOG_ONLY (e.g., mv, sed -i, git rebase)
LOW / SAFE ALLOW (e.g., ls, cat, git status, terminate)

Output control:

  • guard.maxOutputLength now enforced: GatedTool truncates output, Guard triggers retry/fallback

Audit trail:

  • Every tool call logged with: timestamp, tool name, input, risk level, action, result preview, duration
  • Available via gateway.audit.entries / gateway.audit.stats
  • Can be persisted to file via GatewayPolicy.audit_file

Confirmation flow for multi-tenant:

  • highRiskConfirmation: true triggers policy.confirm_callback(tool, input, reason)
  • PaaS can inject a callback that pauses execution and notifies the tenant via API/webhook
  • If no callback configured, HIGH-risk calls are blocked by default (safe default)

Per-tenant policy:

  • Each agent's guard config creates its own GatewayPolicy
  • Tenant A's agent can have dangerousCommandBlock: false (dev mode)
  • Tenant B's agent can have dangerousCommandBlock: true + highRiskConfirmation: true
  • Policies are compiled at agent creation time, not shared across tenants

macOS sandbox fix:

  • RLIMIT_NPROC (block subprocess creation) previously failed silently on macOS
  • Now falls back to Python-level monkey-patching of subprocess/os.system/os.exec*
  • Not a kernel boundary — for production multi-tenant, use L2 container sandbox

6. Network Security

  • Production deployments MUST enforce HTTPS
  • CORS MUST use explicit origin whitelist (NOT *)
  • Rate limiting MUST be enforced per API key
  • Security headers MUST be present on all responses

7. Error Handling

  • Error responses MUST NOT include stack traces or file paths
  • Internal errors MUST be logged server-side with full detail
  • Client-facing errors MUST use generic error codes

8. Credential Storage

  • API keys in CLI config (~/.agentpaas/config.json): plaintext (acceptable for dev)
  • WeChat credentials (~/.agentpaas/wechat/credentials.json): SHOULD be encrypted
  • Database file: SHOULD use encryption at rest in production (PostgreSQL + TDE)

9. Audit Logging

All security-relevant operations MUST be logged:

  • API key creation/revocation
  • Tenant creation/modification
  • Agent deployment/rollback
  • Secret access
  • Authentication failures
  • Admin operations

Implementation Status (2026-03-28)

ID Item Status
SEC-09 Fix sandbox code injection ✅ Input via JSON in sandbox.py
SEC-22 macOS RLIMIT_NPROC fallback ✅ Python-level monkey-patch in sandbox.py
SEC-24 ToolGateway — runtime tool permission enforcement ✅ lambdagent/tool_gateway.py
SEC-25 guard.dangerousCommandBlock enforcement ✅ compiler.py → GatedTool wraps all tools
SEC-26 guard.highRiskConfirmation enforcement ✅ confirm_callback flow in GatedTool
SEC-27 guard.maxOutputLength enforcement ✅ truncation in GatedTool + retry in Guard
SEC-28 Tool call audit logging ✅ AuditLog in tool_gateway.py

TODO List

P0 - Immediate (Critical/High, blocks production)

  • SEC-01: Fix admin endpoints — add authentication to all /api/v1/admin/* routes (2026-04-01)
  • SEC-02: Fix CORS — replace allow_origins=["*"] with configurable whitelist (2026-04-01)
  • SEC-03: Remove scoped_query() from tenant/isolation.py (SQL injection risk) (2026-04-01)
  • SEC-04: Sanitize error responses — hide traceback from clients in api/v1/agents.py (2026-04-01)
  • SEC-05: Require AGENTPAAS_MASTER_KEY — error on startup if not set (non-dev mode) (2026-04-01)

P1 - Week 1 (High, security hardening)

  • SEC-06: Implement rate limiting middleware using TenantContext.rate_limit
  • SEC-07: Fix secrets injection — use Context dict instead of os.environ
  • SEC-08: Add input size validation — max_length on RunRequest.input, config fields
  • SEC-09: Fix sandbox code injection — use JSON file for input, not string interpolation
  • SEC-10: Remove crypto fallback — require cryptography library, no base64 fallback
  • SEC-11: Add HTTPS enforcement middleware for production mode
  • SEC-12: Escape SQL LIKE wildcards in tag search
  • SEC-24: ToolGateway runtime tool permission enforcement (2026-03-28)
  • SEC-25: guard.dangerousCommandBlock enforcement (2026-03-28)
  • SEC-26: guard.highRiskConfirmation enforcement (2026-03-28)
  • SEC-27: guard.maxOutputLength enforcement (2026-03-28)
  • SEC-28: Tool call audit logging (2026-03-28)
  • SEC-29: Wire ToolGateway audit log to PaaS /api/v1/traces endpoint
  • SEC-30: Add confirm_callback webhook — notify tenant on HIGH-risk tool calls via API

P2 - Month 1 (Medium, defense in depth)

  • SEC-13: Upgrade API key hashing to PBKDF2 with salt
  • SEC-14: Add audit logging for security operations
  • SEC-15: Encrypt WeChat credentials file with master key
  • SEC-16: Add security response headers (HSTS, X-Frame-Options, CSP)
  • SEC-17: Add request ID tracking middleware
  • SEC-18: Add LLM call timeout wrapper
  • SEC-19: Migrate to PostgreSQL for production
  • SEC-31: Expose ToolGateway stats in /api/v1/status/agents/{id}/health
  • SEC-32: Per-tenant GatewayPolicy overrides (admin can force strict() for all agents)

P3 - Ongoing (Low, best practices)

  • SEC-20: Implement token rotation policy for WeChat bot tokens
  • SEC-21: Add dependency vulnerability scanning (safety, pip-audit)
  • SEC-22: Platform-specific sandbox fallback when RLIMIT_NPROC unavailable (2026-03-28)
  • SEC-23: API key format upgrade to secrets.token_urlsafe(32)
  • SEC-33: ToolGateway per-agent rate limiting (cap tool calls/min)
  • SEC-34: Integrate ToolGateway audit with OpenTelemetry distributed tracing