fetch_ml/docs/src/multi-tenant-security.md

Multi-Tenant Security Implementation Summary

Overview

This document summarizes the Multi-Tenant Server Security features implemented for tenant isolation, cross-tenant access prevention, resource quotas, worker sanitization, and per-tenant audit logging.

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Tenant Isolation

Tenant Manager (internal/worker/tenant/manager.go)

Core Types:

• Tenant - Represents an isolated tenant with metadata, config, and lifecycle state
• TenantConfig - Holds tenant-specific configuration including quotas and security policies
• IsolationLevel - Defines isolation degree: soft, hard, or dedicated

Key Methods:

• CreateTenant() - Creates isolated tenant workspace with subdirectories (artifacts, snapshots, logs, cache)
• GetTenant() - Retrieves active tenant by ID
• DeactivateTenant() - Soft-delete tenant
• GetTenantWorkspace() - Returns isolated workspace path for tenant
• ListTenants() - Returns all active tenants

Workspace Isolation:

/tenants/
  ├── {tenant-id}/
  │   ├── artifacts/
  │   ├── snapshots/
  │   ├── logs/
  │   └── cache/

Security Defaults (DefaultTenantConfig):

• IsolationLevel: hard (container-level)
• RequireEncryption: true
• RequireAuditLogging: true
• RequireSandbox: true
• NetworkPolicy: "restricted"

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Cross-Tenant Access Prevention

Middleware (internal/worker/tenant/middleware.go)

HTTP Middleware:

• Middleware.Handler() - Validates tenant ID from headers/query params/context
• ExtractTenantID() - Extracts tenant ID from request (header: X-Tenant-ID, query param, or context)
• Automatic audit logging of all tenant requests

Resource Access Control:

• ResourceAccessChecker - Validates cross-tenant resource access
• CheckAccess() - Denies all cross-tenant access by default
• CheckResourceOwnership() - Validates resource belongs to requesting tenant
• ValidateResourcePath() - Ensures path within tenant workspace

Cross-Tenant Denial:

// All cross-tenant access denied by default
if requestingTenantID != resourceTenantID {
    return fmt.Errorf("cross-tenant access denied")
}

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Resource Quotas per Tenant

Quota Manager (internal/worker/tenant/quota.go)

ResourceQuota Structure:

• MaxConcurrentJobs - Job concurrency limit
• MaxGPUs - GPU allocation limit
• MaxMemoryGB - Memory usage limit
• MaxStorageGB - Storage quota
• MaxCPUCores - CPU core limit
• MaxRuntimeHours - Maximum job runtime
• MaxArtifactsPerHour - Artifact creation rate limit

QuotaManager Features:

• CheckQuota() - Validates resource request against tenant limits
• Allocate() - Reserves resources for tenant
• Release() - Frees resources when done
• RecordArtifact() - Tracks artifact creation rate
• Automatic hourly counter reset

Default Quotas:

MaxConcurrentJobs:   5
MaxGPUs:             1
MaxMemoryGB:         32
MaxStorageGB:        100
MaxCPUCores:         8
MaxRuntimeHours:     24
MaxArtifactsPerHour: 10

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Worker Sanitization Between Tenants

Sanitization (internal/worker/tenant/manager.go)

SanitizeForTenant():

• Clears tenant-specific caches
• Logs tenant transition for audit
• Prepares worker environment for different tenant

Called When:

• Worker switches between tenant tasks
• New tenant session begins

Audit Event: AuditWorkerSanitized

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Per-Tenant Audit Logging

Audit Logger (internal/worker/tenant/quota.go)

AuditEvent Types:

• AuditTenantCreated - Tenant provisioned
• AuditTenantDeactivated - Tenant deactivated
• AuditTenantUpdated - Configuration changed
• AuditResourceAccess - Resource accessed
• AuditResourceCreated - Resource created
• AuditResourceDeleted - Resource deleted
• AuditJobSubmitted - Job queued
• AuditJobCompleted - Job finished
• AuditJobFailed - Job error
• AuditCrossTenantDeny - Cross-tenant blocked
• AuditQuotaExceeded - Quota violation
• AuditWorkerSanitized - Worker cleaned
• AuditEncryptionOp - Encryption operation
• AuditDecryptionOp - Decryption operation

Audit Log Structure:

/tenants/
  └── {tenant-id}/
      └── audit.log (JSON format)

Features:

• Per-tenant isolated log files
• Structured JSON format
• IP address tracking
• Success/failure status
• Detailed context in Details field

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Files Created

Core Implementation

1. internal/worker/tenant/manager.go - Tenant lifecycle and isolation
2. internal/worker/tenant/quota.go - Resource quotas and audit logging
3. internal/worker/tenant/middleware.go - HTTP middleware and access control

Worker Integration

4. internal/worker/worker.go - Added TenantManager field to Worker struct

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Testing

Build verification:

make dev  # Successful

All Go packages compile on:

• macOS (Darwin)
• Linux
• Windows

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Security Impact

Feature	Threat Mitigated	Implementation
Tenant Isolation	Data leakage between tenants	Hard isolation with dedicated workspaces
Cross-Tenant Access	Unauthorized data access	Deny-by-default with audit logging
Resource Quotas	Resource exhaustion / DoS	Per-tenant limits with enforcement
Worker Sanitization	Cross-contamination	State clearing between tenant switches
Per-Tenant Audit	Compliance gaps	Isolated audit logs per tenant

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HIPAA Compliance

All features support HIPAA compliance:

• Tenant isolation ensures data separation
• Cross-tenant access prevention blocks unauthorized access
• Per-tenant audit logs enable compliance tracking
• Resource quotas prevent resource-based DoS

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Integration Points

Worker Usage:

// Initialize tenant manager
w.TenantManager, _ = tenant.NewManager("/tenants", w.Logger)

// Create tenant
tenant, _ := w.TenantManager.CreateTenant(ctx, "tenant-1", "Acme Corp", config)

// Validate resource access
err := w.TenantManager.ValidateTenantAccess(ctx, requestingTenant, resourceTenant)

// Sanitize between tenants
w.TenantManager.SanitizeForTenant(ctx, newTenantID)

HTTP Middleware Usage:

middleware := tenant.NewMiddleware(tenantManager, logger)
http.Handle("/api/", middleware.Handler(apiHandler))