Codex CLI¶

Codex CLI is protected via a shell wrapper installed by rampart setup codex. The wrapper runs Codex through Rampart's preload library so spawned shell commands are checked before execution.

Setup¶

rampart setup codex requires the preload library (librampart.so on Linux, librampart.dylib on macOS). If your install does not include it — common for source builds — build and place it first:

mkdir -p ~/.rampart/lib
# Linux
cc -shared -fPIC -o ~/.rampart/lib/librampart.so preload/librampart.c -ldl -lcurl -lpthread
# macOS
cc -dynamiclib -fPIC -o ~/.rampart/lib/librampart.dylib preload/librampart.c -lcurl

Then install the persistent wrapper:

rampart setup codex

# Alternative: wrap a single session
rampart preload -- codex

rampart setup codex installs a wrapper script at ~/.local/bin/codex that transparently runs the real Codex binary through rampart preload. Once installed, every codex invocation is automatically protected — no need to remember to add rampart preload -- each time.

To remove the wrapper: rampart setup codex --remove.

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
                 └─ ask   → blocks until resolved, then allow/deny

Ask behavior: The preload library blocks the exec call and polls the approval API until resolved by a human via rampart approve <id>. The process appears "hung" until approved or denied.

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 before rampart setup codex will create a wrapper. This prevents Rampart from replacing a working codex command with a wrapper that cannot start. If you built Rampart from source, build the library from preload/librampart.c as shown above.

Performance¶

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

Monitor¶

rampart watch