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securitycritical PriorityID: cilium-tetragon-namespace-escape-guardrail-production-standard

Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement

Enforces kernel-level syscall boundary validation via Cilium Tetragon TracingPolicy resources to prevent container breakouts. Intercepts privileged namespace transitions such as sys_enter_setns, sys_enter_unshare, and sys_enter_pivot_root directly in kernel space, issuing synchronous Sigkill actions before host namespaces are compromised. Guarantees deterministic runtime containment by eliminating the latency gap inherent to user-space audit daemons.

Prohibited Anti-Pattern: Passive Audit-Only Logging or Unenforced Syscall Filtering on Namespace Transition Boundaries

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---
description: Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement - Enforces kernel-level syscall boundary validation via Cilium Tetragon TracingPolicy resources to prevent container breakouts. Intercepts privileged namespace transitions such as sys_enter_setns, sys_enter_unshare, and sys_enter_pivot_root directly in kernel space, issuing synchronous Sigkill actions before host namespaces are compromised. Guarantees deterministic runtime containment by eliminating the latency gap inherent to user-space audit daemons.
globs: deploy/**/*.{yaml,yml}, k8s/**/*.{yaml,yml}, security/**/*.{yaml,yml}, tetragon/**/*.{yaml,yml}, helm/**/*.{yaml,yml}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/cilium-tetragon-namespace-escape-guardrail-production-standard"
---

# Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Passive Audit-Only Logging or Unenforced Syscall Filtering on Namespace Transition Boundaries

## System Constraints
You are a Principal Security Architect specializing in Linux kernel security, eBPF internals, and Cilium Tetragon runtime enforcement. Your mandate is to enforce synchronous, in-kernel syscall boundary validation to eliminate container breakout attack surfaces. You must ensure that all security policies handling namespace modification syscalls (setns, unshare, pivot_root) execute deterministic in-kernel terminations (Sigkill) against violating processes rather than delegating containment to user-space logging pipelines.

## Strict Guidelines
- Engineers MUST ALWAYS attach synchronous 'Sigkill' actions to Tetragon TracingPolicy definitions for critical namespace transition syscalls ('sys_enter_setns', 'sys_enter_unshare', 'sys_enter_pivot_root').
- Engineers MUST NOT rely on asynchronous notification streams, user-space SIEM pipelines, or passive audit logs for high-severity container escape events.
- TracingPolicies SHOULD restrict match filters to containerized namespaces, preventing inadvertent disruption of host-level systemd or container runtime daemons.
- Services MUST continuously validate Tetragon BPF sensor attachment health and report degraded sensor states via admission controllers and readiness probes.
- Components NEVER permit untrusted container processes to invoke capability checks via 'cap_capable' targeting CAP_SYS_ADMIN or CAP_SYS_CHROOT without immediate process tree termination.

## Bad vs Good Implementations
### Tetragon TracingPolicy Namespace Breakout Prevention

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: This policy merely audits invocations of setns without an enforcement action. The container breakout executes in nanoseconds, leaving userland monitoring tools to observe an already-compromised host without stopping the attacker.
```yaml
# INSECURE: Passive monitoring policy without kernel-level enforcement
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
  name: audit-namespace-escape
spec:
  kprobes:
    - call: "sys_enter_setns"
      syscall: true
      args:
        - index: 0
          type: "int"
        - index: 1
          type: "int"
      # Fails to enforce in-kernel termination; attacker escapes before userland logs
      selectors:
        - matchNamespaces:
            - namespace: default
              operator: In
      # Missing action: Sigkill
```

#### Production Standard (Correct)
> **Standard**: This policy implements immediate synchronous kernel enforcement via 'action: Sigkill'. The moment an unprivileged or malicious process invokes setns or unshare targeting critical namespaces, the eBPF probe terminates the offending process tree before context switching can finalize the container breakout.
```yaml
# SECURE: In-kernel synchronous termination of namespace escape attempts
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
  name: block-namespace-escape
  labels:
    app.kubernetes.io/part-of: tetragon-runtime-guardrails
spec:
  kprobes:
    - call: "sys_enter_setns"
      syscall: true
      args:
        - index: 0
          type: "int"
        - index: 1
          type: "int"
      selectors:
        - matchArgs:
            - index: 1
              operator: "Mask"
              values:
                - "0x00020000" # CLONE_NEWNET
                - "0x00040000" # CLONE_NEWPID
                - "0x00080000" # CLONE_NEWUSER
                - "0x00000020" # CLONE_NEWNS (Mount)
          matchNamespaces:
            - namespace: kube-system
              operator: NotIn
          matchActions:
            - action: Sigkill
    - call: "sys_enter_unshare"
      syscall: true
      args:
        - index: 0
          type: "int"
      selectors:
        - matchArgs:
            - index: 0
              operator: "Mask"
              values:
                - "0x00000020" # CLONE_NEWNS
                - "0x00040000" # CLONE_NEWPID
          matchActions:
            - action: Sigkill
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Kubernetes Resource Validator MCP
Validates Kubernetes manifests and Cilium CRDs against live cluster APIs and dynamic admission schemes.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

Tetragon CLI & Sensor Inspector
Inspects eBPF map state, sensor hook health, and validates TracingPolicy YAML files against Tetragon kernel requirements.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement

Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement defines an industrial-grade behavioral standard for security engineering. Enforces kernel-level syscall boundary validation via Cilium Tetragon TracingPolicy resources to prevent container breakouts. Intercepts privileged namespace transitions such as sys_enter_setns, sys_enter_unshare, and sys_enter_pivot_root directly in kernel space, issuing synchronous Sigkill actions before host namespaces are compromised. Guarantees deterministic runtime containment by eliminating the latency gap inherent to user-space audit daemons. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Passive Audit-Only Logging or Unenforced Syscall Filtering on Namespace Transition Boundaries Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftPassive Audit-Only Logging or Unenforced Syscall Filtering on Namespace Transition BoundariesCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS attach synchronous 'Sigkill' actions to Tetragon TracingPolicy definitions for critical namespace transition syscalls ('sys_enter_setns', 'sys_enter_unshare', 'sys_enter_pivot_root').

Engineers MUST ALWAYS attach synchronous 'Sigkill' actions to Tetragon TracingPolicy definitions for critical namespace transition syscalls ('sys_enter_setns', 'sys_enter_unshare', 'sys_enter_pivot_root').

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST NOT rely on asynchronous notification streams, user-space SIEM pipelines, or passive audit logs for high-severity container escape events.

Engineers MUST NOT rely on asynchronous notification streams, user-space SIEM pipelines, or passive audit logs for high-severity container escape events.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

TracingPolicies SHOULD restrict match filters to containerized namespaces, preventing inadvertent disruption of host-level systemd or container runtime daemons.

TracingPolicies SHOULD restrict match filters to containerized namespaces, preventing inadvertent disruption of host-level systemd or container runtime daemons.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Services MUST continuously validate Tetragon BPF sensor attachment health and report degraded sensor states via admission controllers and readiness probes.

Services MUST continuously validate Tetragon BPF sensor attachment health and report degraded sensor states via admission controllers and readiness probes.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Components NEVER permit untrusted container processes to invoke capability checks via 'cap_capable' targeting CAP_SYS_ADMIN or CAP_SYS_CHROOT without immediate process tree termination.

Components NEVER permit untrusted container processes to invoke capability checks via 'cap_capable' targeting CAP_SYS_ADMIN or CAP_SYS_CHROOT without immediate process tree termination.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Cilium Tetragon eBPF Synchronous Namespace Escape & Syscall Boundary Enforcement critical for AI coding assistants?

Enforces kernel-level syscall boundary validation via Cilium Tetragon TracingPolicy resources to prevent container breakouts. Intercepts privileged namespace transitions such as sys_enter_setns, sys_enter_unshare, and sys_enter_pivot_root directly in kernel space, issuing synchronous Sigkill actions before host namespaces are compromised. Guarantees deterministic runtime containment by eliminating the latency gap inherent to user-space audit daemons. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Passive Audit-Only Logging or Unenforced Syscall Filtering on Namespace Transition Boundaries) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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