PYSEC-2026-3504

Summary

praisonai.sandbox.SandlockSandbox is documented and implemented as the kernel-enforced sandbox backend for untrusted code. Its SandboxConfig.native() path lets callers configure allowed filesystem paths and network=False.

On systems where the optional sandlock module imports but reports that Landlock is unavailable, SandlockSandbox.execute() and run_command() do not fail closed. They silently fall back to SubprocessSandbox(self.config).

That fallback keeps the same high-level native policy object but does not enforce the native filesystem or network boundary during code execution. A sandboxed payload can read files outside the configured allowed path and open network connections despite network=False.

Technical Details

SandboxConfig.native() creates a restricted native policy and records caller-provided writable paths plus the requested network posture:

return cls(
    sandbox_type="native",
    working_dir=os.getcwd(),
    security_policy=SecurityPolicy(
        allow_network=network,
        allow_file_write=True,
        allow_subprocess=True,
        allowed_paths=resolved_paths,
    ),
    metadata={"writable_paths": resolved_paths, "network": network},
)

SandlockSandbox builds the intended kernel policy with Landlock-backed filesystem allowlisting and network denial:

policy = Policy(
    fs_readable=allowed_read_paths,
    fs_writable=allowed_write_paths,
    net_allow_hosts=[] if not limits.network_enabled else None,
    max_memory=f"{limits.memory_mb}M",
    max_processes=limits.max_processes,
    max_open_files=limits.max_open_files,
)

However, both execution paths fail open when Sandlock is unavailable:

if not self.is_available:
    logger.warning("Sandlock not available, falling back to subprocess")
    from .subprocess import SubprocessSandbox
    fallback = SubprocessSandbox(self.config)
    return await fallback.execute(code, language, limits, env, working_dir)
```...