[CRITICAL] Implement TLS/mTLS configuration for secure communications

[claranceliberi]

Problem Statement

The metrics agent transmits potentially sensitive system data over unencrypted HTTP connections, creating a significant security vulnerability. No TLS configuration options exist, and all communications are plaintext.

Impact Assessment

• Severity: Critical
• Impact: Data interception, man-in-the-middle attacks, compliance violations
• Affected Components: All metric transmissions, diagnostic data, agent communications
• Security Risk: High - Sensitive system information exposed in transit
• Compliance: Violates SOC 2, GDPR, HIPAA requirements

Technical Details

Current State

• File: pkg/clients/tsclient/client.go
• Lines: 82-84, 142-148
• Issues:
  • No TLS configuration in HTTP transport
  • No certificate validation
  • Hardcoded insecure transport settings
  • Missing client certificate support

Code Analysis

// Line 82-84 - Insecure transport
transport := &http.Transport{
    MaxIdleConns:        10,
    IdleConnTimeout:     30 * time.Second,
    // Missing TLS configuration
}

// Lines 142-148 - Plaintext transmission
req, err := http.NewRequestWithContext(ctx, "POST", c.endpoint, bytes.NewBuffer(compressed))
// No certificate validation, no encryption

Acceptance Criteria

• Implement TLS 1.3 minimum version requirement
• Add certificate validation with configurable CA bundle
• Implement mutual TLS (mTLS) support for client authentication
• Add certificate pinning for enhanced security
• Support custom cipher suites configuration
• Add TLS connection logging and monitoring
• Implement certificate rotation mechanism
• Add configuration options for all TLS settings

Implementation Guidelines

1. TLS Configuration Structure:

type TLSConfig struct {
    Enabled           bool     `yaml:"enabled"`
    MinVersion        string   `yaml:"min_version"`
    CipherSuites      []string `yaml:"cipher_suites"`
    InsecureSkipVerify bool    `yaml:"insecure_skip_verify"`
    CertFile          string   `yaml:"cert_file"`
    KeyFile           string   `yaml:"key_file"`
    CAFile            string   `yaml:"ca_file"`
    ServerName        string   `yaml:"server_name"`
}

2. Security Requirements:

   • Default to TLS 1.3, fallback to TLS 1.2
   • Disable weak cipher suites
   • Enable certificate validation by default
   • Support both file-based and embedded certificates

3. mTLS Implementation:

   • Client certificate authentication
   • Automatic certificate renewal
   • Certificate health monitoring

Testing Requirements

• Unit tests for TLS configuration parsing
• Integration tests with real TLS servers
• Security tests for certificate validation
• Performance tests for TLS overhead
• Compatibility tests with different TLS versions

Security Considerations

• Certificate Storage: Secure storage of private keys
• Key Rotation: Automated certificate renewal
• Monitoring: TLS connection health and certificate expiry
• Fallback: Graceful degradation options

Configuration Example

tls:
  enabled: true
  min_version: "1.3"
  cert_file: "/etc/ssl/certs/agent.crt"
  key_file: "/etc/ssl/private/agent.key"
  ca_file: "/etc/ssl/ca-bundle.pem"
  server_name: "metrics.example.com"
  insecure_skip_verify: false

Related Issues

• Blocks: Authentication framework implementation ([CRITICAL] Implement authentication and authorization framework #3)
• Related to: Audit logging and compliance ([DOCUMENTATION] Comprehensive documentation and compliance framework #13)
• Depends on: Configuration management improvements

Definition of Done

• TLS 1.3 implemented with secure defaults
• mTLS support for client authentication
• Certificate validation working correctly
• Configuration options documented
• Security tests passing
• Performance impact < 5% overhead
• Code review by security team