landstrip 0.9.0

Sandbox for coding agents with parametrized state
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102

# landstrip

`landstrip` runs a command in an OS-level sandbox using Landlock LSM on Linux,
Seatbelt on macOS, and LPAC AppContainer on Windows.  It accepts the Anthropic
Sandbox Runtime JSON subset as the policy.

## Installation

### npm

```sh
npm install --save-dev @jarkkojs/landstrip
```

```sh
npx landstrip -p policy.json cargo test
```

The npm package installs a small Node.js wrapper and a platform-specific native
binary package.

## Backends

| Area         | macOS                    | Linux                        | Windows                         |
| ------------ | ------------------------ | ---------------------------- | ------------------------------- |
| Policy       | path based rules         | file based rules             | access control list (ACL)       |
| Timing       | dynamic subset of paths  | file based static ruleset    | persistent ACLs                 |
| TCP          | localhost proxy ports    | loopback proxy ports         | unsupported                     |
| Unix sockets | allowlist                | allowlist via seccomp broker | unsupported                     |

Windows uses an AppContainer. The backend grants the generated AppContainer SID
access to the lowered read and write roots, so Windows policies must use
explicit read allowlists. Fine-grained TCP and Unix socket policies are rejected
until Windows enforcement exists.

## Network Policy

Sandbox mode denies direct network access by default. Proxy ports, local binding,
and Unix sockets can be allowed with the Anthropic Sandbox Runtime network fields.

For a filesystem-only sandbox with unrestricted direct network access, set:

```json
{
  "network": {
    "allowNetwork": true
  }
}
```

On Linux and macOS, `allowNetwork` disables landstrip network enforcement while
leaving filesystem policy enforcement in place. Windows rejects unrestricted
network policies until Windows network support exists.

## JSON Output

Failures reported by `landstrip` are printed as one compact JSON object on
standard output. This covers policy, command launch, capability, and system
errors. Usage errors are not JSON responses; they remain on standard error and
exit with status 2.

```json
{"code":"policy","file":"policy.json","message":"expected value at line 1 column 1"}
```

```json
{"code":"command","command":"missing-tool","message":"No such file or directory"}
```

The `code` field is one of `policy`, `command`, `capability`, or `system`. The
`file` field is present when a policy error is tied to a policy file. The
`command` field is present when landstrip could not start or encode a command.

Logs and sandboxed command output are not part of the JSON response. Normal
successful command execution does not print a landstrip JSON response because
standard output belongs to the sandboxed command.

## Development

### Commit messages

- **`<subsystem>: <message>`**
- Long description for non-trivial changes.
- Kernel style commit messages.
- **`Signed-off-by`**

### Documenting errors

The following snippet demonstrates the recommended pattern for documenting
the return values on error:

```
/// # Errors
///
/// Returns [`<variant's unqualified name>`](<variant's unqualified name>)
/// Returns ...
```

## Licensing

The JavaScript npm wrapper is licensed under `Apache-2.0`. The Rust source and
native binaries are licensed under `LGPL-2.1-or-later`.