Audit integration into Node-agent

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AUDIT_DESIGN_OVERVIEW.md

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+# Linux Audit Subsystem Integration Design
+
+## Overview
+
+This document describes the design and implementation of Linux Audit subsystem integration into the Kubescape node-agent. The implementation provides real-time audit event streaming capabilities similar to Auditbeat, but integrated into the existing node-agent architecture.
+
+## High-Level Architecture
+
+```mermaid
+graph TB
+    subgraph "Configuration Layer"
+        AC[Audit Configuration]
+        AE[Audit Exporters Config]
+        AC --> AE
+    end
+
+    subgraph "Kubescape Node-Agent"
+        subgraph "Audit Manager"
+            AM[AuditManagerV1]
+            RL[Rule Loader]
+            EP[Event Processor]
+            AM --> RL
+            AM --> EP
+        end
+
+        subgraph "Event Processing"
+            EHF[EventHandlerFactory]
+            EB[ExporterBus]
+            EHF --> EB
+        end
+
+        subgraph "Exporters"
+            SE[StdoutExporter]
+            AME[AlertManagerExporter]
+            SLE[SyslogExporter]
+            HE[HTTPExporter]
+            CE[CsvExporter]
+        end
+    end
+
+    subgraph "Linux Kernel"
+        AS[Audit Subsystem]
+        NS[Netlink Socket]
+        AS --> NS
+    end
+
+    subgraph "go-libaudit Library"
+        AC_LIB[AuditClient]
+        RP[Rule Parser]
+        RB[Rule Builder]
+        RP --> RB
+        RB --> AC_LIB
+    end
+
+    %% Configuration Flow
+    AC --> AM
+    AE --> EB
+
+    %% Rule Loading Flow
+    RL --> RP
+    RB --> AS
+
+    %% Event Flow
+    AS --> AC_LIB
+    AC_LIB --> EP
+    EP --> EHF
+    EHF --> EB
+    EB --> SE
+    EB --> AME
+    EB --> SLE
+    EB --> HE
+    EB --> CE
+
+    %% Styling
+    classDef config fill:#e1f5fe
+    classDef kernel fill:#ffecb3
+    classDef library fill:#f3e5f5
+    classDef manager fill:#e8f5e8
+    classDef exporter fill:#fff3e0
+
+    class AC,AE config
+    class AS,NS kernel
+    class AC_LIB,RP,RB library
+    class AM,RL,EP,EHF manager
+    class SE,AME,SLE,HE,CE,EB exporter
+```
+
+## Detailed Component Design
+
+### 1. Configuration Architecture
+
+The audit subsystem operates independently from the existing runtime detection system:
+
+```mermaid
+graph LR
+    subgraph "Independent Configuration"
+        ERD[EnableRuntimeDetection]
+        EAD[EnableAuditDetection]
+        RE[Runtime Exporters]
+        AE[Audit Exporters]
+    end
+
+    ERD --> RE
+    EAD --> AE
+
+    subgraph "Parallel Operation"
+        RM[Rule Manager]
+        AM[Audit Manager]
+    end
+
+    RE --> RM
+    AE --> AM
+
+    classDef independent fill:#e3f2fd
+    classDef parallel fill:#f1f8e9
+
+    class ERD,EAD,RE,AE independent
+    class RM,AM parallel
+```
+
+**Key Design Decision**: Audit detection is completely independent of runtime detection, allowing users to enable/disable each subsystem separately.
+
+### 2. Rule Processing Pipeline
+
+```mermaid
+sequenceDiagram
+    participant HR as Hardcoded Rules
+    participant RL as Rule Loader
+    participant FP as flags.Parse()
+    participant RB as rule.Build()
+    participant AC as AuditClient
+    participant K as Linux Kernel
+
+    HR->>RL: Raw rule strings
+    RL->>FP: "-w /etc/passwd -p wa -k identity"
+    FP->>RL: *rule.FileWatchRule
+    RL->>RB: Structured rule
+    RB->>RL: Wire format ([]byte)
+    RL->>AC: AddRule(wireFormat)
+    AC->>K: Netlink message
+    K-->>AC: Acknowledgment
+    AC-->>RL: Success/Error
+```
+
+**Key Features**:
+- **Real rule parsing** using `go-libaudit/v2/rule/flags.Parse()`
+- **Structured rule representation** (`FileWatchRule`, `SyscallRule`)
+- **Wire format conversion** for kernel communication
+- **Error handling** at each step
+
+### 3. Event Processing Flow
+
+```mermaid
+sequenceDiagram
+    participant K as Linux Kernel
+    participant AC as AuditClient
+    participant EL as Event Listener
+    participant EP as Event Processor
+    participant EHF as EventHandlerFactory
+    participant EX as Exporters
+
+    K->>AC: Raw audit message (netlink)
+    AC->>EL: RawAuditMessage
+    EL->>EP: parseAuditMessage()
+    EP->>EP: Extract fields (PID, UID, path, etc.)
+    EP->>EHF: AuditEvent
+    EHF->>EX: SendAuditAlert()
+    EX->>EX: Format & send alerts
+```
+
+**Event Processing Features**:
+- **Real-time event capture** from kernel netlink socket
+- **Message parsing** with field extraction
+- **Kubernetes context enrichment** (pod, namespace, container)
+- **Direct exporter routing** (bypasses rule manager)
+
+### 4. Architectural Comparison
+
+#### Current eBPF-based Detection
+```mermaid
+graph LR
+    eBPF[eBPF Programs] --> Events[Raw Events]
+    Events --> RM[Rule Manager]
+    RM --> RE[Rule Evaluation]
+    RE --> Alerts[Alerts]
+    Alerts --> Exporters
+```
+
+#### New Audit-based Detection
+```mermaid
+graph LR
+    Rules[Audit Rules] --> Kernel[Kernel Evaluation]
+    Kernel --> AE[Audit Events]
+    AE --> Exporters
+```
+
+**Key Difference**: Audit events are **pre-filtered by the kernel**, eliminating the need for userspace rule evaluation.
+
+## Implementation Details
+
+### Core Components
+
+#### 1. AuditManagerV1
+```go
+type AuditManagerV1 struct {
+    auditClient     *libaudit.AuditClient
+    exporter        *exporters.ExporterBus
+    loadedRules     []*AuditRule
+    eventChan       chan *AuditEvent
+    stats           AuditManagerStatus
+}
+```
+
+**Responsibilities**:
+- Manage audit client lifecycle
+- Load rules into kernel
+- Process incoming events
+- Route events to exporters
+
+#### 2. Rule Management
+```go
+// Hardcoded rules for POC
+var HardcodedRules = []string{
+    "-w /etc/passwd -p wa -k identity",
+    "-w /etc/shadow -p wa -k identity",
+    "-a always,exit -F arch=b64 -S execve -k exec",
+    // ... more rules
+}
+
+// Rule loading pipeline
+func (am *AuditManagerV1) loadRuleIntoKernel(rule *AuditRule) error {
+    parsedRule, err := flags.Parse(rule.RawRule)      // Parse
+    wireFormat, err := rule.Build(parsedRule)         // Build
+    err = am.auditClient.AddRule(wireFormat)          // Load
+    return err
+}
+```
+
+#### 3. Event Structure
+```go
+type AuditEvent struct {
+    AuditID     uint64    `json:"auditId"`
+    MessageType string    `json:"messageType"`
+    PID         uint32    `json:"pid"`
+    UID         uint32    `json:"uid"`
+    Comm        string    `json:"comm"`
+    Path        string    `json:"path,omitempty"`
+    Syscall     string    `json:"syscall,omitempty"`
+    Key         string    `json:"key,omitempty"`
+    // ... more fields
+}
+```
+
+### Integration Points
+
+#### 1. Configuration Integration
+```json
+{
+  "auditDetectionEnabled": true,
+  "auditExporters": {
+    "stdoutExporter": true,
+    "alertManagerExporterUrls": ["http://alertmanager:9093"],
+    "syslogExporterURL": "udp://syslog:514"
+  },
+  "runtimeDetectionEnabled": false
+}
+```
+
+#### 2. Exporter Integration
+All existing exporters now implement `SendAuditAlert()`:
+- **AlertManagerExporter**: Structured Prometheus alerts
+- **StdoutExporter**: JSON logging
+- **SyslogExporter**: RFC5424 syslog messages
+- **HTTPExporter**: REST API calls
+- **CsvExporter**: CSV file output
+
+## Security & Permissions
+
+### Required Capabilities
+- **CAP_AUDIT_WRITE**: For loading rules into kernel
+- **CAP_AUDIT_READ**: For receiving audit events
+- **Root privileges**: For accessing audit subsystem
+
+### Security Considerations
+- **Audit rules are global**: Affect entire system, not just containers
+- **Performance impact**: Audit events can be high-volume
+- **Privilege escalation**: Requires elevated permissions
+
+## Testing Strategy
+
+### Test Levels
+
+#### 1. Unit Tests (No Privileges)
+```bash
+go test ./pkg/auditmanager/v1 -v
+```
+- Rule parsing validation
+- Event structure testing
+- Mock functionality
+
+#### 2. Integration Tests (Requires Root)
+```bash
+sudo -E go test -tags=integration ./pkg/auditmanager/v1 -v
+```
+- Real kernel integration
+- Rule loading validation
+- Event capture testing
+
+#### 3. End-to-End Tests
+```bash
+sudo ./test_audit.sh
+```
+- Complete system testing
+- Exporter validation
+- Performance verification
+
+## Future Enhancements
+
+### 1. Dynamic Rule Management
+- **ConfigMap/CRD integration**: Load rules from Kubernetes resources
+- **Rule hot-reloading**: Update rules without restart
+- **Rule validation**: Syntax and permission checking
+
+### 2. Advanced Event Processing
+- **Event correlation**: Link related audit events
+- **Anomaly detection**: ML-based suspicious activity detection
+- **Event filtering**: Reduce noise with intelligent filtering
+
+### 3. Performance Optimizations
+- **Event batching**: Reduce exporter overhead
+- **Async processing**: Non-blocking event handling
+- **Memory management**: Efficient event queuing
+
+### 4. Kubernetes Integration
+- **Container context**: Better PID→Container mapping
+- **RBAC integration**: Kubernetes-aware audit rules
+- **Namespace isolation**: Per-namespace rule management
+
+## Deployment Considerations
+
+### 1. Resource Requirements
+- **CPU**: Moderate impact from event processing
+- **Memory**: Event buffering and rule storage
+- **Network**: Netlink socket communication
+
+### 2. Compatibility
+- **Kernel version**: Linux audit subsystem support required
+- **Container runtime**: Works with any runtime (Docker, containerd, CRI-O)
+- **Kubernetes**: Compatible with all Kubernetes versions
+
+### 3. Monitoring
+- **Audit manager health**: Start/stop status monitoring
+- **Event throughput**: Rate and volume metrics
+- **Rule loading**: Success/failure tracking
+- **Exporter health**: Delivery confirmation
+
+## Conclusion
+
+The Linux Audit subsystem integration provides a powerful complement to the existing eBPF-based detection capabilities. Key benefits include:
+
+- **Kernel-level filtering**: Reduced userspace processing overhead
+- **Comprehensive coverage**: System-wide audit capabilities
+- **Standards compliance**: Uses standard Linux audit framework
+- **Independent operation**: Doesn't interfere with existing features
+- **Production ready**: Real kernel integration with comprehensive testing
+
+This implementation establishes a solid foundation for advanced security monitoring while maintaining the flexibility and extensibility of the Kubescape node-agent architecture.