Files
codex/codex-rs/core/tests/suite/skill_approval.rs
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.
```
2026-02-25 11:05:27 -08:00

649 lines
21 KiB
Rust

#![allow(clippy::expect_used, clippy::unwrap_used)]
use anyhow::Result;
use codex_core::features::Feature;
#[cfg(unix)]
use codex_protocol::models::FileSystemPermissions;
#[cfg(unix)]
use codex_protocol::models::PermissionProfile;
use codex_protocol::protocol::AskForApproval;
use codex_protocol::protocol::EventMsg;
use codex_protocol::protocol::Op;
use codex_protocol::protocol::SandboxPolicy;
use codex_protocol::skill_approval::SkillApprovalResponse;
use core_test_support::responses::ev_assistant_message;
use core_test_support::responses::ev_completed;
use core_test_support::responses::ev_function_call;
use core_test_support::responses::ev_response_created;
use core_test_support::responses::mount_function_call_agent_response;
use core_test_support::responses::mount_sse_sequence;
use core_test_support::responses::sse;
use core_test_support::responses::start_mock_server;
use core_test_support::skip_if_no_network;
use core_test_support::test_codex::TestCodex;
use core_test_support::test_codex::test_codex;
use core_test_support::wait_for_event;
use core_test_support::wait_for_event_match;
use pretty_assertions::assert_eq;
use serde_json::json;
use std::fs;
use std::path::Path;
use std::path::PathBuf;
fn write_skill_with_script(home: &Path, name: &str, script_body: &str) -> Result<PathBuf> {
let skill_dir = home.join("skills").join(name);
let scripts_dir = skill_dir.join("scripts");
fs::create_dir_all(&scripts_dir)?;
fs::write(
skill_dir.join("SKILL.md"),
format!(
r#"---
name: {name}
description: {name} skill
---
"#
),
)?;
let script_path = scripts_dir.join("run.py");
fs::write(&script_path, script_body)?;
Ok(script_path)
}
#[cfg(unix)]
fn write_skill_metadata(home: &Path, name: &str, contents: &str) -> Result<()> {
let metadata_dir = home.join("skills").join(name).join("agents");
fs::create_dir_all(&metadata_dir)?;
fs::write(metadata_dir.join("openai.yaml"), contents)?;
Ok(())
}
fn shell_command_arguments(command: &str) -> Result<String> {
Ok(serde_json::to_string(&json!({
"command": command,
"timeout_ms": 500,
}))?)
}
fn assistant_response(message: &str) -> String {
sse(vec![
ev_response_created("resp-2"),
ev_assistant_message("msg-1", message),
ev_completed("resp-2"),
])
}
fn command_for_script(script_path: &Path) -> Result<String> {
let runner = if cfg!(windows) { "python" } else { "python3" };
let script_path = script_path.to_string_lossy().into_owned();
Ok(shlex::try_join([runner, script_path.as_str()])?)
}
async fn submit_turn(test: &TestCodex, prompt: &str) -> Result<()> {
submit_turn_with_policies(
test,
prompt,
AskForApproval::Never,
SandboxPolicy::DangerFullAccess,
)
.await
}
async fn submit_turn_with_policies(
test: &TestCodex,
prompt: &str,
approval_policy: AskForApproval,
sandbox_policy: SandboxPolicy,
) -> Result<()> {
let session_model = test.session_configured.model.clone();
test.codex
.submit(Op::UserTurn {
items: vec![codex_protocol::user_input::UserInput::Text {
text: prompt.to_string(),
text_elements: Vec::new(),
}],
final_output_json_schema: None,
cwd: test.cwd_path().to_path_buf(),
approval_policy,
sandbox_policy,
model: session_model,
effort: None,
summary: codex_protocol::config_types::ReasoningSummary::Auto,
collaboration_mode: None,
personality: None,
})
.await?;
Ok(())
}
async fn wait_for_turn_complete_without_skill_approval(test: &TestCodex) {
wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::SkillRequestApproval(request) => {
panic!("unexpected skill approval request: {request:?}");
}
EventMsg::TurnComplete(_) => Some(()),
_ => None,
})
.await;
}
#[cfg(unix)]
fn write_skill_with_shell_script(home: &Path, name: &str, script_name: &str) -> Result<PathBuf> {
use std::os::unix::fs::PermissionsExt;
let skill_dir = home.join("skills").join(name);
let scripts_dir = skill_dir.join("scripts");
fs::create_dir_all(&scripts_dir)?;
fs::write(
skill_dir.join("SKILL.md"),
format!(
r#"---
name: {name}
description: {name} skill
---
"#
),
)?;
let script_path = scripts_dir.join(script_name);
fs::write(
&script_path,
r#"#!/bin/sh
echo 'zsh-fork-stdout'
echo 'zsh-fork-stderr' >&2
"#,
)?;
let mut permissions = fs::metadata(&script_path)?.permissions();
permissions.set_mode(0o755);
fs::set_permissions(&script_path, permissions)?;
Ok(script_path)
}
#[cfg(unix)]
fn find_test_zsh_path() -> Result<Option<PathBuf>> {
use core_test_support::fetch_dotslash_file;
let repo_root = codex_utils_cargo_bin::repo_root()?;
let dotslash_zsh = repo_root.join("codex-rs/app-server/tests/suite/zsh");
if !dotslash_zsh.is_file() {
eprintln!(
"skipping zsh-fork skill test: shared zsh DotSlash file not found at {}",
dotslash_zsh.display()
);
return Ok(None);
}
match fetch_dotslash_file(&dotslash_zsh, None) {
Ok(path) => Ok(Some(path)),
Err(error) => {
eprintln!("skipping zsh-fork skill test: failed to fetch zsh via dotslash: {error:#}");
Ok(None)
}
}
}
#[cfg(unix)]
fn supports_exec_wrapper_intercept(zsh_path: &Path) -> bool {
let status = std::process::Command::new(zsh_path)
.arg("-fc")
.arg("/usr/bin/true")
.env("EXEC_WRAPPER", "/usr/bin/false")
.status();
match status {
Ok(status) => !status.success(),
Err(_) => false,
}
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn skill_approval_event_round_trip_for_shell_command_skill_script_exec() -> Result<()> {
skip_if_no_network!(Ok(()));
let server = start_mock_server().await;
let tool_call_id = "shell-skill-call";
let mut builder = test_codex()
.with_pre_build_hook(|home| {
write_skill_with_script(home, "demo", "print('shell skill approved')").unwrap();
})
.with_config(|config| {
config.features.enable(Feature::SkillApproval);
});
let test = builder.build(&server).await?;
let script_path = test.codex_home_path().join("skills/demo/scripts/run.py");
let command = command_for_script(&script_path)?;
let arguments = shell_command_arguments(&command)?;
let _mocks =
mount_function_call_agent_response(&server, tool_call_id, &arguments, "shell_command")
.await;
submit_turn(&test, "run the shell skill").await?;
let request = wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::SkillRequestApproval(request) => Some(request.clone()),
_ => None,
})
.await;
assert_eq!(request.item_id, tool_call_id);
assert_eq!(request.skill_name, "demo");
test.codex
.submit(Op::SkillApproval {
id: request.item_id,
response: SkillApprovalResponse { approved: true },
})
.await?;
wait_for_event(test.codex.as_ref(), |event| {
matches!(event, EventMsg::TurnComplete(_))
})
.await;
Ok(())
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn skill_approval_not_emitted_without_skill_script_exec() -> Result<()> {
skip_if_no_network!(Ok(()));
let server = start_mock_server().await;
let tool_call_id = "non-skill-call";
let mut builder = test_codex().with_config(|config| {
config.features.enable(Feature::SkillApproval);
});
let test = builder.build(&server).await?;
let arguments = shell_command_arguments("echo no-skill")?;
let _mocks =
mount_function_call_agent_response(&server, tool_call_id, &arguments, "shell_command")
.await;
submit_turn(&test, "run a plain command").await?;
wait_for_turn_complete_without_skill_approval(&test).await;
Ok(())
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn skill_approval_decline_blocks_execution() -> Result<()> {
skip_if_no_network!(Ok(()));
let server = start_mock_server().await;
let tool_call_id = "decline-call";
let marker_name = "declined-marker.txt";
let mut builder = test_codex()
.with_pre_build_hook(move |home| {
let marker_path = home.join(marker_name);
let marker_path = marker_path.to_string_lossy();
let script_body = format!(
r#"from pathlib import Path
Path({marker_path:?}).write_text('ran')
print('ran')
"#
);
write_skill_with_script(home, "demo", &script_body).unwrap();
})
.with_config(|config| {
config.features.enable(Feature::SkillApproval);
});
let test = builder.build(&server).await?;
let script_path = test.codex_home_path().join("skills/demo/scripts/run.py");
let command = command_for_script(&script_path)?;
let arguments = shell_command_arguments(&command)?;
let mocks =
mount_function_call_agent_response(&server, tool_call_id, &arguments, "shell_command")
.await;
submit_turn(&test, "run the skill").await?;
let request = wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::SkillRequestApproval(request) => Some(request.clone()),
_ => None,
})
.await;
assert_eq!(request.item_id, tool_call_id);
test.codex
.submit(Op::SkillApproval {
id: request.item_id,
response: SkillApprovalResponse { approved: false },
})
.await?;
wait_for_event(test.codex.as_ref(), |event| {
matches!(event, EventMsg::TurnComplete(_))
})
.await;
let marker_path = test.codex_home_path().join(marker_name);
assert!(
!marker_path.exists(),
"declined skill approval should block script execution"
);
let call_output = mocks
.completion
.single_request()
.function_call_output(tool_call_id);
assert_eq!(
call_output["output"].as_str(),
Some("This script is part of the skill and the user declined the skill usage"),
);
Ok(())
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn skill_approval_cache_is_per_skill() -> Result<()> {
skip_if_no_network!(Ok(()));
let server = start_mock_server().await;
let first_call_id = "skill-a-1";
let second_call_id = "skill-a-2";
let third_call_id = "skill-b-1";
let mut builder = test_codex()
.with_pre_build_hook(|home| {
write_skill_with_script(home, "alpha", "print('alpha')").unwrap();
write_skill_with_script(home, "beta", "print('beta')").unwrap();
})
.with_config(|config| {
config.features.enable(Feature::SkillApproval);
});
let test = builder.build(&server).await?;
let alpha_command =
command_for_script(&test.codex_home_path().join("skills/alpha/scripts/run.py"))?;
let beta_command =
command_for_script(&test.codex_home_path().join("skills/beta/scripts/run.py"))?;
let first_alpha_arguments = shell_command_arguments(&alpha_command)?;
let second_alpha_arguments = shell_command_arguments(&alpha_command)?;
let beta_arguments = shell_command_arguments(&beta_command)?;
mount_sse_sequence(
&server,
vec![
sse(vec![
ev_response_created("resp-1"),
ev_function_call(first_call_id, "shell_command", &first_alpha_arguments),
ev_completed("resp-1"),
]),
assistant_response("alpha-1"),
sse(vec![
ev_response_created("resp-1"),
ev_function_call(second_call_id, "shell_command", &second_alpha_arguments),
ev_completed("resp-1"),
]),
assistant_response("alpha-2"),
sse(vec![
ev_response_created("resp-1"),
ev_function_call(third_call_id, "shell_command", &beta_arguments),
ev_completed("resp-1"),
]),
assistant_response("beta-1"),
],
)
.await;
submit_turn(&test, "run alpha").await?;
let first_request = wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::SkillRequestApproval(request) => Some(request.clone()),
_ => None,
})
.await;
assert_eq!(first_request.item_id, first_call_id);
assert_eq!(first_request.skill_name, "alpha");
test.codex
.submit(Op::SkillApproval {
id: first_request.item_id,
response: SkillApprovalResponse { approved: true },
})
.await?;
wait_for_event(test.codex.as_ref(), |event| {
matches!(event, EventMsg::TurnComplete(_))
})
.await;
submit_turn(&test, "run alpha again").await?;
wait_for_turn_complete_without_skill_approval(&test).await;
submit_turn(&test, "run beta").await?;
let third_request = wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::SkillRequestApproval(request) => Some(request.clone()),
_ => None,
})
.await;
assert_eq!(third_request.item_id, third_call_id);
assert_eq!(third_request.skill_name, "beta");
test.codex
.submit(Op::SkillApproval {
id: third_request.item_id,
response: SkillApprovalResponse { approved: true },
})
.await?;
wait_for_event(test.codex.as_ref(), |event| {
matches!(event, EventMsg::TurnComplete(_))
})
.await;
Ok(())
}
#[cfg(unix)]
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn shell_zsh_fork_prompts_for_skill_script_execution() -> Result<()> {
use codex_config::Constrained;
use codex_protocol::protocol::ReviewDecision;
skip_if_no_network!(Ok(()));
let Some(zsh_path) = find_test_zsh_path()? else {
return Ok(());
};
if !supports_exec_wrapper_intercept(&zsh_path) {
eprintln!(
"skipping zsh-fork skill test: zsh does not support EXEC_WRAPPER intercepts ({})",
zsh_path.display()
);
return Ok(());
}
let Ok(main_execve_wrapper_exe) = codex_utils_cargo_bin::cargo_bin("codex-execve-wrapper")
else {
eprintln!("skipping zsh-fork skill test: unable to resolve `codex-execve-wrapper` binary");
return Ok(());
};
let server = start_mock_server().await;
let tool_call_id = "zsh-fork-skill-call";
let mut builder = test_codex()
.with_pre_build_hook(|home| {
write_skill_with_shell_script(home, "mbolin-test-skill", "hello-mbolin.sh").unwrap();
write_skill_metadata(
home,
"mbolin-test-skill",
r#"
permissions:
file_system:
read:
- "./data"
write:
- "./output"
"#,
)
.unwrap();
})
.with_config(move |config| {
config.features.enable(Feature::ShellTool);
config.features.enable(Feature::ShellZshFork);
config.zsh_path = Some(zsh_path.clone());
config.main_execve_wrapper_exe = Some(main_execve_wrapper_exe);
config.permissions.allow_login_shell = false;
config.permissions.approval_policy = Constrained::allow_any(AskForApproval::OnRequest);
config.permissions.sandbox_policy =
Constrained::allow_any(SandboxPolicy::new_workspace_write_policy());
});
let test = builder.build(&server).await?;
let script_path = fs::canonicalize(
test.codex_home_path()
.join("skills/mbolin-test-skill/scripts/hello-mbolin.sh"),
)?;
let script_path_str = script_path.to_string_lossy().into_owned();
let command = shlex::try_join([script_path_str.as_str()])?;
let arguments = shell_command_arguments(&command)?;
let mocks =
mount_function_call_agent_response(&server, tool_call_id, &arguments, "shell_command")
.await;
submit_turn_with_policies(
&test,
"use $mbolin-test-skill",
AskForApproval::OnRequest,
SandboxPolicy::new_workspace_write_policy(),
)
.await?;
let maybe_approval = wait_for_event_match(test.codex.as_ref(), |event| match event {
EventMsg::ExecApprovalRequest(request) => Some(Some(request.clone())),
EventMsg::TurnComplete(_) => Some(None),
_ => None,
})
.await;
let approval = match maybe_approval {
Some(approval) => approval,
None => {
let call_output = mocks
.completion
.single_request()
.function_call_output(tool_call_id);
panic!(
"expected exec approval request before completion; function_call_output={call_output:?}"
);
}
};
assert_eq!(approval.call_id, tool_call_id);
assert_eq!(approval.command, vec![script_path_str.clone()]);
assert_eq!(
approval.additional_permissions,
Some(PermissionProfile {
file_system: Some(FileSystemPermissions {
read: Some(vec![PathBuf::from("./data")]),
write: Some(vec![PathBuf::from("./output")]),
}),
..Default::default()
})
);
test.codex
.submit(Op::ExecApproval {
id: approval.effective_approval_id(),
turn_id: None,
decision: ReviewDecision::Approved,
})
.await?;
wait_for_event(test.codex.as_ref(), |event| {
matches!(event, EventMsg::TurnComplete(_))
})
.await;
let call_output = mocks
.completion
.single_request()
.function_call_output(tool_call_id);
let output = call_output["output"].as_str().unwrap_or_default();
assert!(
output.contains("zsh-fork-stdout"),
"expected stdout marker in function_call_output: {output:?}"
);
assert!(
output.contains("zsh-fork-stderr"),
"expected stderr marker in function_call_output: {output:?}"
);
Ok(())
}
#[cfg(unix)]
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn shell_zsh_fork_still_enforces_workspace_write_sandbox() -> Result<()> {
use codex_config::Constrained;
use codex_protocol::protocol::AskForApproval;
skip_if_no_network!(Ok(()));
let Some(zsh_path) = find_test_zsh_path()? else {
return Ok(());
};
if !supports_exec_wrapper_intercept(&zsh_path) {
eprintln!(
"skipping zsh-fork sandbox test: zsh does not support EXEC_WRAPPER intercepts ({})",
zsh_path.display()
);
return Ok(());
}
let Ok(main_execve_wrapper_exe) = codex_utils_cargo_bin::cargo_bin("codex-execve-wrapper")
else {
eprintln!(
"skipping zsh-fork sandbox test: unable to resolve `codex-execve-wrapper` binary"
);
return Ok(());
};
let server = start_mock_server().await;
let tool_call_id = "zsh-fork-workspace-write-deny";
let outside_path = "/tmp/codex-zsh-fork-workspace-write-deny.txt";
let workspace_write_policy = SandboxPolicy::WorkspaceWrite {
writable_roots: Vec::new(),
read_only_access: Default::default(),
network_access: false,
exclude_tmpdir_env_var: true,
exclude_slash_tmp: true,
};
let policy_for_config = workspace_write_policy.clone();
let _ = fs::remove_file(outside_path);
let mut builder = test_codex()
.with_pre_build_hook(move |_| {
let _ = fs::remove_file(outside_path);
})
.with_config(move |config| {
config.features.enable(Feature::ShellTool);
config.features.enable(Feature::ShellZshFork);
config.zsh_path = Some(zsh_path.clone());
config.main_execve_wrapper_exe = Some(main_execve_wrapper_exe);
config.permissions.allow_login_shell = false;
config.permissions.approval_policy = Constrained::allow_any(AskForApproval::Never);
config.permissions.sandbox_policy = Constrained::allow_any(policy_for_config);
});
let test = builder.build(&server).await?;
let command = format!("touch {outside_path}");
let arguments = shell_command_arguments(&command)?;
let mocks =
mount_function_call_agent_response(&server, tool_call_id, &arguments, "shell_command")
.await;
submit_turn_with_policies(
&test,
"write outside workspace with zsh fork",
AskForApproval::Never,
workspace_write_policy,
)
.await?;
wait_for_turn_complete_without_skill_approval(&test).await;
let call_output = mocks
.completion
.single_request()
.function_call_output(tool_call_id);
let output = call_output["output"].as_str().unwrap_or_default();
assert!(
output.contains("Permission denied")
|| output.contains("Operation not permitted")
|| output.contains("Read-only file system"),
"expected sandbox denial, got output: {output:?}"
);
assert!(
!Path::new(outside_path).exists(),
"command should not write outside workspace under WorkspaceWrite policy"
);
Ok(())
}