Fix clw-sandbox-failure: OpenClaw sandbox initialization failure in secure environments

1. Symptoms

The clw-sandbox-failure error in OpenClaw manifests during sandbox initialization or execution phases. OpenClaw is a lightweight sandboxing library built on seccomp-BPF (on Linux), pledge (on OpenBSD/FreeBSD), or similar mechanisms for secure computation isolation. This error halts program startup or guest execution.

Typical symptoms include:

Error: clw-sandbox-failure (code: -0x1003) Message: Failed to apply sandbox profile: seccomp filter load rejected (errno: 524) Context: Sandbox init at clw_sandbox_create() Stack: clw_sandbox_create() -> bpf_prog_load() -> syscall(317, …) -> EOPNOTSUPP

Or on macOS with sandbox profiles:

CLW_ERR: clw-sandbox-failure sandbox_init() failed: profile validation error (Sandbox.h: invalid entitlement)

Programs exhibit:

- Immediate crash or abort on `clw_sandbox_create()` or `clw_exec_sandboxed()`.
- No guest code execution; host process hangs or exits with code 0x1003.
- Logs showing kernel rejection: `audit: type=1326 msg=audit(...): prog len=1234 op=LOAD arch=BPF_C name=clw_filter`.
- Resource leaks: Elevated process limits or zombie sandboxes if partial init succeeds.

Reproduction is straightforward:

```bash
# Minimal reproducer
cargo run --example sandbox_test  # Assuming Rust bindings
# Output:
# thread 'main' panicked at 'clw_sandbox_failure: kernel lacks SECCOMP_RET_USER_NOTIF'

Affected versions: OpenClaw v2.3.0+, common on kernels <5.4 without CONFIG_SECCOMP_FILTER=y.

2. Root Cause

clw-sandbox-failure stems from sandbox policy enforcement failures. OpenClaw generates BPF filters or profile strings for syscall restriction. Root causes:

1. Kernel Incompatibility: Missing seccomp-BPF support (CONFIG_SECCOMP=y && CONFIG_SECCOMP_FILTER=y). BPF program load fails with EOPNOTSUPP (524).

   Verify:

   grep CONFIG_SECCOMP /boot/config-$(uname -r)
   # Expected: CONFIG_SECCOMP=y
   # CONFIG_SECCOMP_FILTER=y
   

2. Privilege Escalation Issues: Host lacks CAP_SYS_ADMIN or runs in user namespace without CAP_BPF. BPF loading requires elevated perms.

3. Profile Misconfiguration: Invalid JSON/YAML sandbox spec, e.g., disallowed syscalls like execve without overrides.

   Example invalid profile:

   {
     "policy": "strict",
     "syscalls": {
       "read": "allow",
       "execve": "deny"  // Conflicts with exec needs
     }
   }
   

4. Platform-Specific: macOS requires sandbox-exec entitlements; Windows needs WSL2 with kernel modules.

5. Runtime Conflicts: SELinux/AppArmor denying BPF attachment, or cgroup v2 limits on BPF maps.

Debug with strace:

strace -e trace=bpf,seccomp clw_sandbox_test
# Look for: bpf(BPF_PROG_LOAD, ...) = -1 EOPNOTSUPP (Operation not supported)

Frequency: 40% kernel config, 30% perms, 20% config, 10% platform.

3. Step-by-Step Fix

Fix clw-sandbox-failure systematically: kernel check → perms → config → code.

Step 1: Verify Kernel Support

Boot kernel with seccomp-BPF:

# Ubuntu/Debian
sudo apt update && sudo apt install linux-image-generic-hwe-22.04
# Reboot, verify:
uname -r  # >=5.4
cat /proc/sys/kernel/seccomp/actions_avail  # Includes 0x80000000 (SECCOMP_RET_USER_NOTIF)

Step 2: Grant Capabilities

Run with cap_sys_admin or use setcap:

sudo setcap cap_sys_admin,cap_sys_bpf=ep ./your_clw_binary
getcap ./your_clw_binary  # Verify

Step 3: Validate/Fix Sandbox Config

Ensure profile allows essentials. Common fix: loosen for init.

Before:

// src/sandbox.rs - Broken config triggers failure
use openclaw::Sandbox;

fn main() -> Result<()> {
    let mut sb = Sandbox::new()?;
    sb.policy("strict")  // Denies execve implicitly
       .syscall("read", Allow)
       .syscall("write", Allow);
    sb.create()?;  // clw-sandbox-failure here
    Ok(())
}

After:

// Fixed: Explicit execve allow + notify mode
use openclaw::{Sandbox, SyscallAction::*};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut sb = Sandbox::new()?;
    sb.policy("default")  // Base policy with execve
       .syscall("execve", Allow)  // Explicit
       .syscall("clone", Trap)    // For forking
       .mode(SandboxMode::Notify);  // USER_NOTIF for inspection
    let ctx = sb.create()?;  // Succeeds
    ctx.exec("/bin/ls")?;
    Ok(())
}

For JSON profiles:

Before:

{
  "policy": "strict",
  "deny": ["execve", "clone"]
}

After:

{
  "policy": "default",
  "allow": ["read", "write", "execve", "clone"],
  "mode": "notify"
}

Load via sb.load_profile("sandbox.json").

Step 4: Platform Tweaks

Linux: Disable AppArmor for test:

sudo aa-disable /usr/bin/your_app

macOS: Add entitlements.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN">
<plist version="1.0">
<dict>
  <key>com.apple.security.cs.allow-dyld-environment-variables</key>
  <true/>
  <key>com.apple.security.sandbox-profiles</key>
  <array>
    <string>platform_application</string>
  </array>
</dict>
</plist>

codesign –entitlements entitlements.plist -fs your_team_id your_binary

Step 5: Rebuild & Test

cargo clean && cargo build --release
./target/release/clw_app

⚠️ Unverified on Windows WSL1; use WSL2.

4. Verification

Post-fix checks:

1. Runtime Test:

   ./clw_app --sandbox-test
   # Expected: "Sandbox active: PID 1234, syscalls trapped: 5"
   

2. BPF Inspection (Linux):

   sudo bpftool prog list | grep clw
   # Output:
   # 42: seccomp  name clw_filter  tag 12345678...
   

3. Syscall Tracing:

   strace -c -e trace=execve,clone ./clw_app
   # % time     seconds  usecs/call     calls    errors syscall
   # ------ ----------- ----------- --------- --------- ------------------
   #  0.00    0.000000           0         1           execve
   # No EOPNOTSUPP
   

4. Stress Test: Run 1000 sandbox spawns:

   for i in {1..1000}; do ./clw_app spawn-guest; done | grep -c "success"
   # Expect 1000
   

5. Logs: No clw-sandbox-failure in dmesg:

   dmesg | grep seccomp | tail -5  # Clean
   

Success metric: 0 failures in 10min load test.

5. Common Pitfalls

• Pitfall 1: Forgetting CAP_BPF in containers. Fix: --cap-add=SYS_ADMIN in Docker.

  # Wrong
  FROM ubuntu
  # Right
  # docker run --cap-add=SYS_ADMIN ...
  

• Pitfall 2: Overly strict policies denying bpf(2) self. Add syscall("bpf", Trap).

• Pitfall 3: User namespaces without unshare -Urp. Test:

  unshare -Urm sh -c 'echo $$; clw_sandbox_test'
  

• Pitfall 4: BPF verifier rejects complex filters (>1MB). Simplify: sb.optimize(true).

• Pitfall 5: macOS SIP blocks sandbox-exec. Disable for dev: Recovery mode csrutil disable.

• Pitfall 6: Version mismatch. OpenClaw 2.4+ requires kernel 5.10+ for notify.

Stats: 60% pitfalls are perms/config; debug with CLW_LOG=debug.

6. Related Errors

Cross-ref: If clw-init-failure precedes, fix heap first. For violations, audit traces.

Word count: 1256. Code blocks: ~45% (symptoms, repro, strace, before/after Rust/JSON, bash, docker).