# Security Hardening Plan

## 🎯 **Objective**

Implement comprehensive security measures to protect apt-ostree from various attack vectors while maintaining system functionality and user experience.

## 🛡️ **Security Threats**

### **1. Privilege Escalation**
- **Unauthorized system modifications** through package installation
- **Root access** through malicious package scripts
- **System compromise** through package vulnerabilities

### **2. Data Integrity**
- **Package tampering** during download or installation
- **Repository compromise** leading to malicious packages
- **System state corruption** through failed operations

### **3. Information Disclosure**
- **Sensitive system information** exposure
- **User data leakage** through logging or debugging
- **Configuration details** accessible to unauthorized users

### **4. Denial of Service**
- **Resource exhaustion** through malicious operations
- **System instability** through package conflicts
- **Service disruption** through transaction failures

## 🔒 **Security Measures**

### **1. Authentication and Authorization**

#### **Polkit Integration**
```rust
// Enhanced Polkit authorization
pub struct SecurityManager {
    authority: Authority,
    policies: HashMap<String, SecurityPolicy>,
    user_cache: LruCache<String, UserPermissions>,
}

impl SecurityManager {
    pub async fn check_authorization(
        &self,
        action: &str,
        user: &str,
        details: &HashMap<String, String>,
    ) -> AptOstreeResult<bool> {
        let policy = self.policies.get(action)
            .ok_or_else(|| AptOstreeError::Security("Unknown action".to_string()))?;
        
        let permissions = self.get_user_permissions(user).await?;
        
        if policy.requires_root && !permissions.is_root {
            return Ok(false);
        }
        
        if policy.requires_specific_user && !policy.allowed_users.contains(user) {
            return Ok(false);
        }
        
        Ok(true)
    }
}
```

#### **User Role Management**
```rust
// User role definitions
#[derive(Debug, Clone)]
pub enum UserRole {
    Administrator,    // Full system access
    PowerUser,       // Package management access
    StandardUser,    // Read-only access
    Guest,           // Minimal access
}

impl UserRole {
    pub fn can_install_packages(&self) -> bool {
        matches!(self, UserRole::Administrator | UserRole::PowerUser)
    }
    
    pub fn can_modify_system(&self) -> bool {
        matches!(self, UserRole::Administrator)
    }
}
```

### **2. Input Validation and Sanitization**

#### **Package Name Validation**
```rust
// Secure package name validation
pub fn validate_package_name(name: &str) -> AptOstreeResult<()> {
    // Check for path traversal attempts
    if name.contains("..") || name.contains("/") || name.contains("\\") {
        return Err(AptOstreeError::Security(
            "Invalid package name: path traversal detected".to_string()
        ));
    }
    
    // Check for command injection attempts
    let dangerous_chars = [';', '&', '|', '$', '(', ')', '`'];
    if dangerous_chars.iter().any(|&c| name.contains(c)) {
        return Err(AptOstreeError::Security(
            "Invalid package name: command injection detected".to_string()
        ));
    }
    
    // Check length limits
    if name.len() > 100 {
        return Err(AptOstreeError::Security(
            "Package name too long".to_string()
        ));
    }
    
    Ok(())
}
```

#### **Path Validation**
```rust
// Secure path validation
pub fn validate_system_path(path: &str) -> AptOstreeResult<()> {
    let path = std::path::Path::new(path);
    
    // Prevent path traversal
    if path.components().any(|component| {
        matches!(component, std::path::Component::ParentDir)
    }) {
        return Err(AptOstreeError::Security(
            "Path traversal detected".to_string()
        ));
    }
    
    // Restrict to system directories
    let allowed_prefixes = [
        "/usr",
        "/etc",
        "/var",
        "/opt",
        "/home",
    ];
    
    let is_allowed = allowed_prefixes.iter().any(|&prefix| {
        path.starts_with(prefix)
    });
    
    if !is_allowed {
        return Err(AptOstreeError::Security(
            "Access to path not allowed".to_string()
        ));
    }
    
    Ok(())
}
```

### **3. Secure Communication**

#### **DBus Security**
```rust
// Secure DBus interface
#[dbus_interface(name = "org.projectatomic.aptostree1")]
impl DaemonDBus {
    #[dbus_interface(property)]
    async fn get_system_status(&self) -> Result<String, Box<dyn std::error::Error>> {
        // Verify caller permissions
        let caller = self.get_caller_info().await?;
        if !self.security_manager.check_authorization("get_status", &caller.user, &HashMap::new()).await? {
            return Err("Access denied".into());
        }
        
        Ok(self.get_status().await?)
    }
    
    async fn install_packages(
        &self,
        packages: Vec<String>,
        #[zbus(header)] hdr: MessageHeader<'_>,
    ) -> Result<String, Box<dyn std::error::Error>> {
        // Validate caller
        let caller = self.get_caller_info().await?;
        
        // Validate package names
        for package in &packages {
            validate_package_name(package)?;
        }
        
        // Check authorization
        if !self.security_manager.check_authorization("install_packages", &caller.user, &HashMap::new()).await? {
            return Err("Access denied".into());
        }
        
        // Execute installation
        Ok(self.execute_installation(packages).await?)
    }
}
```

#### **Network Security**
```rust
// Secure network operations
pub struct SecureNetworkManager {
    tls_config: TlsConfig,
    certificate_store: CertificateStore,
    allowed_hosts: HashSet<String>,
}

impl SecureNetworkManager {
    pub async fn secure_download(
        &self,
        url: &str,
        destination: &Path,
    ) -> AptOstreeResult<()> {
        // Validate URL
        let parsed_url = url::Url::parse(url)
            .map_err(|_| AptOstreeError::Security("Invalid URL".to_string()))?;
        
        // Check allowed hosts
        if !self.allowed_hosts.contains(parsed_url.host_str().unwrap_or("")) {
            return Err(AptOstreeError::Security("Host not allowed".to_string()));
        }
        
        // Verify TLS certificate
        let certificate = self.get_certificate(parsed_url.host_str().unwrap()).await?;
        if !self.verify_certificate(&certificate).await? {
            return Err(AptOstreeError::Security("Invalid certificate".to_string()));
        }
        
        // Download with integrity verification
        self.download_with_verification(url, destination).await
    }
}
```

### **4. Data Integrity and Verification**

#### **Package Integrity**
```rust
// Package integrity verification
pub struct PackageVerifier {
    hash_algorithms: Vec<HashAlgorithm>,
    signature_verifier: SignatureVerifier,
}

impl PackageVerifier {
    pub async fn verify_package(
        &self,
        package_path: &Path,
        expected_hash: &str,
        signature: Option<&[u8]>,
    ) -> AptOstreeResult<()> {
        // Calculate package hash
        let actual_hash = self.calculate_hash(package_path).await?;
        
        if actual_hash != expected_hash {
            return Err(AptOstreeError::Security(
                "Package hash mismatch".to_string()
            ));
        }
        
        // Verify signature if provided
        if let Some(sig) = signature {
            if !self.signature_verifier.verify(package_path, sig).await? {
                return Err(AptOstreeError::Security(
                    "Package signature verification failed".to_string()
                ));
            }
        }
        
        Ok(())
    }
}
```

#### **System State Verification**
```rust
// System state verification
pub struct SystemStateVerifier {
    checksum_store: ChecksumStore,
    integrity_checker: IntegrityChecker,
}

impl SystemStateVerifier {
    pub async fn verify_system_integrity(&self) -> AptOstreeResult<()> {
        let critical_paths = [
            "/usr/bin",
            "/usr/lib",
            "/etc",
            "/var/lib",
        ];
        
        for path in &critical_paths {
            let checksum = self.checksum_store.get_checksum(path).await?;
            let actual_checksum = self.calculate_path_checksum(path).await?;
            
            if checksum != actual_checksum {
                return Err(AptOstreeError::Security(
                    format!("System integrity check failed for {}", path)
                ));
            }
        }
        
        Ok(())
    }
}
```

### **5. Audit and Logging**

#### **Security Audit Log**
```rust
// Security audit logging
pub struct SecurityAuditLogger {
    log_writer: Arc<Mutex<File>>,
    sensitive_operations: HashSet<String>,
}

impl SecurityAuditLogger {
    pub async fn log_security_event(
        &self,
        event_type: SecurityEventType,
        user: &str,
        operation: &str,
        details: &HashMap<String, String>,
        success: bool,
    ) -> AptOstreeResult<()> {
        let timestamp = chrono::Utc::now();
        let event = SecurityEvent {
            timestamp,
            event_type,
            user: user.to_string(),
            operation: operation.to_string(),
            details: details.clone(),
            success,
            ip_address: self.get_client_ip().await?,
            session_id: self.get_session_id().await?,
        };
        
        let log_entry = serde_json::to_string(&event)?;
        let mut writer = self.log_writer.lock().await;
        writeln!(writer, "{}", log_entry)?;
        
        // Alert on sensitive operations
        if self.sensitive_operations.contains(operation) {
            self.send_security_alert(&event).await?;
        }
        
        Ok(())
    }
}
```

## 🔧 **Implementation Plan**

### **Phase 1: Foundation (Week 5)**
- [ ] Implement Polkit integration
- [ ] Add input validation framework
- [ ] Set up security audit logging
- [ ] Create security policy definitions

### **Phase 2: Core Security (Week 5)**
- [ ] Implement package integrity verification
- [ ] Add secure communication protocols
- [ ] Implement user role management
- [ ] Add path validation and sanitization

### **Phase 3: Advanced Security (Week 6)**
- [ ] Implement system state verification
- [ ] Add network security measures
- [ ] Implement advanced authentication
- [ ] Add intrusion detection features

### **Phase 4: Validation (Week 6)**
- [ ] Security penetration testing
- [ ] Vulnerability assessment
- [ ] Security audit review
- [ ] Compliance validation

## 📊 **Security Metrics**

### **Quantitative Goals**
- **Vulnerability reduction**: 90% reduction in known vulnerabilities
- **Attack prevention**: 95% success rate in preventing common attacks
- **Response time**: < 1 second for security event detection
- **False positive rate**: < 5% for security alerts

### **Qualitative Goals**
- **Compliance**: Meet industry security standards
- **Transparency**: Clear security policies and procedures
- **Maintainability**: Easy security policy updates
- **User experience**: Minimal security overhead

## 🚨 **Security Policies**

### **Default Security Policy**
```yaml
security:
  default_policy: "deny"
  allowed_operations:
    - "read_system_status"
    - "list_packages"
    - "search_packages"
  
  restricted_operations:
    - "install_packages"
    - "remove_packages"
    - "modify_system"
    - "upgrade_system"
  
  authentication:
    required: true
    methods: ["polkit", "sudo"]
  
  authorization:
    admin_users: ["root", "sudo"]
    power_users: ["admin", "system"]
    standard_users: ["user"]
```

## 🔗 **Related Documentation**

- [Security Model](../architecture/responsibility-analysis.md)
- [CLI Architecture](../architecture/cli-command-structure.md)
- [Package Management](../architecture/apt-library-analysis.md)
- [Testing Strategy](../implementation/testing-strategy.md)
- [Deployment Guide](../implementation/deployment-guide.md)
