> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://docs.nvidia.com/nemoclaw/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/nemoclaw/_mcp/server. # Review Sandbox Hardening > Security hardening measures applied to the NemoClaw sandbox container image. The NemoClaw sandbox image applies several security measures to reduce the attack surface and limit damage from untrusted workloads. ## Removed Unnecessary Tools NemoClaw explicitly purges build toolchains (`gcc`, `g++`, `make`) and network probes (`netcat`) from the runtime image. These tools are not needed at runtime and would widen the attack surface. The runtime image keeps a small set of operational utilities for normal sandbox workflows, including `vi`, `jq`, and `dos2unix`. Use these utilities for lightweight inspection and file cleanup inside the sandbox, but make durable image or policy changes in the NemoClaw source tree and rebuild the sandbox. If you need a compiler during build, use the existing multi-stage build. The `builder` stage has full Node.js tooling. Copy only artifacts into the runtime stage. ## Process Limits The container ENTRYPOINT sets `ulimit -u 512` to cap the number of processes a sandbox user can spawn. This mitigates fork-bomb attacks. The startup script (`nemoclaw-start.sh`) applies the same limit. Adjust the value with the `--ulimit nproc=512:512` flag if you launch with `docker run` directly. ## Open File Descriptor Limits The same ENTRYPOINT also sets `ulimit -n 65536` to cap the number of open file descriptors a sandbox user can hold. Without this cap, the sandbox inherits the Docker daemon default (`nofile` \~1048576), which can exceed the host runtime limit and let a runaway process exhaust file descriptors. The startup script (`nemoclaw-start.sh`) applies the same limit. Adjust the value with the `--ulimit nofile=65536:65536` flag if you launch with `docker run` directly. Like the process limit, this limit applies to the PID 1 entrypoint process tree, which includes the gateway and agent. `openshell sandbox connect` shells spawn outside that tree and still inherit the runtime default (tracked upstream in NVIDIA/OpenShell#1452). Enforce both limits at the container runtime when that residual risk matters to you. ## Dropping Linux Capabilities The NemoClaw entrypoint drops dangerous capabilities from the process bounding set before it starts agent services. It removes `CAP_SYS_ADMIN`, `CAP_SYS_PTRACE`, `CAP_NET_RAW`, `CAP_DAC_OVERRIDE`, `CAP_SYS_CHROOT`, `CAP_FSETID`, `CAP_SETFCAP`, `CAP_MKNOD`, `CAP_AUDIT_WRITE`, and `CAP_NET_BIND_SERVICE`. When `setpriv` is available, the entrypoint also removes the remaining privilege-separation capabilities during the switch from root to the `sandbox` and `gateway` users. The bounding-set drop is best effort: if `capsh` or `CAP_SETPCAP` is unavailable the entrypoint logs a warning and continues with the runtime-provided capability set. If `setpriv` is unavailable, the entrypoint falls back to `gosu`. To make the drop fail-closed instead, set `NEMOCLAW_REQUIRE_CAP_DROP=1` in the entrypoint environment: the agent then refuses to start unless the agent process tree's bounding set is verified free of the dangerous capabilities. This is opt-in because many hosts cannot drop capabilities, including cloud VMs, Docker Desktop, and WSL environments without `CAP_SETPCAP`. The check covers the agent process tree only. For defense-in-depth, also drop all Linux capabilities at the container runtime when you launch the image directly. In the examples below, `nemoclaw-sandbox` is a placeholder for the sandbox image NemoClaw builds during onboarding; substitute the image tag your install produced, which you can find with `docker images`. ```bash docker run --rm \ --cap-drop=ALL \ --ulimit nproc=512:512 \ --ulimit nofile=65536:65536 \ nemoclaw-sandbox ``` ### Docker Compose Example ```yaml services: nemoclaw-sandbox: image: nemoclaw-sandbox:latest cap_drop: - ALL cap_add: - NET_BIND_SERVICE ulimits: nproc: soft: 512 hard: 512 nofile: soft: 65536 hard: 65536 security_opt: - no-new-privileges:true read_only: true tmpfs: - /tmp:size=64m ``` The `Dockerfile` itself cannot enforce `--cap-drop`. The container orchestrator controls that runtime setting. Always configure capability dropping in your `docker run` flags, Compose file, or Kubernetes `securityContext`. ## Filesystem Layout The sandbox Landlock policy declares which paths are writable. The agent's home directory (`/sandbox`) is writable by default: | Path | Access | Purpose | | -------------------- | ------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `/sandbox` | read-write | Home directory where agents can create files and use standard home paths | | `/sandbox/.openclaw` | read-write | Agent config, state, workspace, plugins | | `/sandbox/.nemoclaw` | read-write (Landlock); DAC-restricted | Parent directory is `root:root` mode `1755`; the sandbox user can write only to `state/`, `migration/`, `snapshots/`, `staging/`, and `config.json`. `blueprints/` and the parent itself are root-owned to prevent tampering. | | `/tmp` | read-write | Temporary files and logs | The `Access` column reflects the Landlock policy declaration only. Actual write success additionally requires POSIX (DAC) ownership and permissions to allow it. For example, Landlock lists `/sandbox/.nemoclaw` as writable, but the sandbox user cannot create files directly under it because the parent directory is root-owned; writes must target the sandbox-owned subdirectories listed above. This writable default is intentional. Seeing the sandbox user create files under `/sandbox` or `/sandbox/.openclaw` in a fresh sandbox does not mean Landlock failed. Landlock still enforces the fixed read-only system paths below. System paths remain read-only for these protections: * Agents cannot replace system binaries with trojanized versions. * Agents cannot modify DNS resolution or TLS trust stores. * Agents cannot tamper with libraries or shell configuration outside `/sandbox`. The image build pre-creates locked shell init files `.bashrc` and `.profile` without proxy entries. System-wide shell hooks that read `/tmp/nemoclaw-proxy-env.sh` source the runtime proxy configuration. ### Landlock Kernel Requirements Landlock LSM requires Linux kernel 5.13 or later with `CONFIG_SECURITY_LANDLOCK=y`. The NemoClaw sandbox policy uses `compatibility: best_effort`, which means Landlock enforcement is silently skipped on kernels that do not support it. On such kernels, protection falls back to DAC (file ownership and permissions) only. Files outside the writable paths would be inaccessible to the agent regardless of DAC permissions. Verify Landlock availability: ```bash ls /sys/kernel/security/landlock ``` On a kernel with Landlock support, the path exists and `ls` succeeds. If it reports `No such file or directory`, the kernel does not expose Landlock, and the sandbox falls back to DAC-only enforcement as described above. For production deployments, use kernel 5.13+ with Landlock enabled. The `test/e2e/e2e-cloud-experimental/checks/04-landlock-readonly.sh` script validates enforcement at runtime. ## References * [#804](https://github.com/NVIDIA/NemoClaw/issues/804): Filesystem layout and Landlock policy * [#807](https://github.com/NVIDIA/NemoClaw/issues/807): gcc in sandbox image * [#808](https://github.com/NVIDIA/NemoClaw/issues/808): netcat in sandbox image * [#809](https://github.com/NVIDIA/NemoClaw/issues/809): No process limit * [#4527](https://github.com/NVIDIA/NemoClaw/issues/4527): Cap open file descriptors (nofile) * [#797](https://github.com/NVIDIA/NemoClaw/issues/797): Drop Linux capabilities