codex

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Michael Bolin 648a420cbf fix: enforce sandbox envelope for zsh fork execution (#12800 )

## Why
Zsh fork execution was still able to bypass the `WorkspaceWrite` model
in edge cases because the fork path reconstructed command execution
without preserving sandbox wrappers, and command extraction only
accepted shell invocations in a narrow positional shape. This can allow
commands to run with broader filesystem access than expected, which
breaks the sandbox safety model.

## What changed
- Preserved the sandboxed `ExecRequest` produced by
`attempt.env_for(...)` when entering the zsh fork path in
[`unix_escalation.rs`](https://github.com/openai/codex/blob/main/codex-rs/core/src/tools/runtimes/shell/unix_escalation.rs).
- Updated `CoreShellCommandExecutor` to execute the sandboxed command
and working directory captured from `attempt.env_for(...)`, instead of
re-running a freshly reconstructed shell command.
- Made zsh-fork script extraction robust to wrapped invocations by
scanning command arguments for `-c`/`-lc` rather than only matching the
first positional form.
- Added unit tests in `unix_escalation.rs` to lock in wrapper-tolerant
parsing behavior and keep unsupported shell forms rejected.
- Tightened the regression in
[`skill_approval.rs`](https://github.com/openai/codex/blob/main/codex-rs/core/tests/suite/skill_approval.rs):
- `shell_zsh_fork_still_enforces_workspace_write_sandbox` now uses an
explicit `WorkspaceWrite` policy with `exclude_tmpdir_env_var: true` and
`exclude_slash_tmp: true`.
- The test attempts to write to `/tmp/...`, which is only reliably
outside writable roots with those explicit exclusions set.

## Verification
- Added and passed the new unit tests around `extract_shell_script`
parsing behavior with wrapped command shapes.
  - `extract_shell_script_supports_wrapped_command_prefixes`
  - `extract_shell_script_rejects_unsupported_shell_invocation`
- Verified the regression with the focused integration test:
`shell_zsh_fork_still_enforces_workspace_write_sandbox`.

## Manual Testing

Prior to this change, if I ran Codex via:

```
just codex --config zsh_path=/Users/mbolin/code/codex2/codex-rs/app-server/tests/suite/zsh --enable shell_zsh_fork
```

and asked:

```
what is the output of /bin/ps
```

it would run it, even though the default sandbox should prevent the
agent from running `/bin/ps` because it is setuid on MacOS.

But with this change, I now see the expected failure because it is
blocked by the sandbox:

```
/bin/ps exited with status 1 and produced no output in this environment.
```

648a420cbf · 2026-02-25 11:05:27 -08:00

History

common

Agent jobs (spawn_agents_on_csv) + progress UI (#10935 )

2026-02-24 21:00:19 +00:00

fixtures

Update tests to stop using sse_completed fixture (#10638 )

2026-02-04 08:38:06 -08:00

suite

fix: enforce sandbox envelope for zsh fork execution (#12800 )

2026-02-25 11:05:27 -08:00

all.rs