# landstrip
`landstrip` runs a tool 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, in JSON or YAML syntax.
## 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.
## Platforms
| 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 platform 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.
## Policy Format
JSON is the default policy format. Use `--format yml` for YAML policy files or
YAML read from standard input.
```sh
landstrip --format yml -p policy.yml cargo test
```
YAML path fields can use normal lists or one statement per line:
```yml
filesystem:
allowWrite: |
.
~/.cargo
denyRead: |
~/.ssh
allowRead: |
~/.ssh/config
network:
allowNetwork: true
```
## 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 error. This covers policy, tool launch, platform, and system
errors. Usage errors are not JSON responses; they remain on standard error and
exit with status 2.
```json
{"category":"policy","file":"policy.json","message":"expected value at line 1 column 1"}
```
```json
{"category":"tool","program":"cargo","type":"launch","message":"No such file or directory"}
```
The `category` field is one of `policy`, `tool`, `platform`, or `system`. The
`file` field is present when a policy error is tied to a policy file. The
`program` field is present when landstrip could not start or encode a tool. The
`type` field is present for policy or tool errors and is either `filesystem`,
`network`, or `platform` for policy errors, or `launch` (failed to start
the tool) or `encoding` (failed to encode the command line) for tool errors.
Logs and sandboxed tool output are not part of the JSON response. Normal
successful tool execution does not print a landstrip JSON response because
standard error belongs to landstrip; standard output belongs to the sandboxed tool.
## 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`.