Codex CLI¶

Codex CLI doesn't have a hook system or $SHELL support. Rampart uses LD_PRELOAD to intercept exec syscalls at the OS level — the universal fallback.

Setup¶

rampart preload -- codex

That's it. Every command Codex tries to execute goes through Rampart first.

How It Works¶

Codex CLI
  └─ calls execve("rm", ["-rf", "/"], env)
       └─ librampart.so intercepts (LD_PRELOAD)
            └─ HTTP POST to rampart /v1/preflight/exec
                 ├─ allow → real execve() runs
                 └─ deny  → returns EPERM

The preload library intercepts:

• execve — primary exec syscall
• execvp / execvpe — PATH-resolved variants
• system() — libc shell wrapper
• popen() — pipe to shell command
• posix_spawn() — modern spawn API

Monitor Mode¶

Log everything without blocking:

rampart preload --mode monitor -- codex

Platform Support¶

Requirements¶

The preload library (librampart.so or librampart.dylib) must be installed. It's included in Homebrew installs and release tarballs, or build from preload/ in the source tree.

Performance¶

The library adds <1ms per intercepted call via Unix socket, <3ms via TCP. Fail-open is instant (<0.01ms).

Monitor¶

rampart watch