nanobot/nanobot/agent/tools/sandbox.py

50 lines
1.7 KiB
Python

"""Sandbox backends for shell command execution.
To add a new backend, implement a function with the signature:
_wrap_<name>(command: str, workspace: str, cwd: str) -> str
and register it in _BACKENDS below.
"""
import shlex
from pathlib import Path
def _bwrap(command: str, workspace: str, cwd: str) -> str:
"""Wrap command in a bubblewrap sandbox (requires bwrap in container).
Only the workspace is bind-mounted read-write; its parent dir (which holds
config.json) is hidden behind a fresh tmpfs.
"""
ws = Path(workspace).resolve()
try:
sandbox_cwd = str(ws / Path(cwd).resolve().relative_to(ws))
except ValueError:
sandbox_cwd = str(ws)
required = ["/usr"]
optional = ["/bin", "/lib", "/lib64", "/etc/alternatives",
"/etc/ssl/certs", "/etc/resolv.conf", "/etc/ld.so.cache"]
args = ["bwrap", "--new-session", "--die-with-parent"]
for p in required: args += ["--ro-bind", p, p]
for p in optional: args += ["--ro-bind-try", p, p]
args += [
"--proc", "/proc", "--dev", "/dev", "--tmpfs", "/tmp",
"--tmpfs", str(ws.parent), # mask config dir
"--dir", str(ws), # recreate workspace mount point
"--bind", str(ws), str(ws),
"--chdir", sandbox_cwd,
"--", "sh", "-c", command,
]
return shlex.join(args)
_BACKENDS = {"bwrap": _bwrap}
def wrap_command(sandbox: str, command: str, workspace: str, cwd: str) -> str:
"""Wrap *command* using the named sandbox backend."""
if backend := _BACKENDS.get(sandbox):
return backend(command, workspace, cwd)
raise ValueError(f"Unknown sandbox backend {sandbox!r}. Available: {list(_BACKENDS)}")