Sandbox an untrusted binary with bubblewrap: read-only system dirs and a private /tmp
domain: github.com/containers/bubblewrap · 8 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Bind the host's base system read-only: bwrap --ro-bind /usr /usr, then recreate top-level symlinks as the official demo does: --symlink usr/bin /bin --symlink usr/lib /lib --symlink usr/lib64 /lib64 --symlink usr/sbin /sbin.
Give the sandbox a private /tmp: --dir /tmp (empty dir, as in the demo) or --tmpfs /tmp for a fresh tmpfs.
Mount fresh procfs and devtmpfs: --proc /proc --dev /dev (never bind the host's real /proc or /dev).
Set the working directory explicitly with --chdir /.
Isolate namespaces with --unshare-all (equivalent to --unshare-user-try --unshare-ipc --unshare-pid --unshare-net --unshare-uts --unshare-cgroup-try).
Append the untrusted binary as the trailing command: bwrap <options> /path/to/untrusted-binary.
Add --die-with-parent so the sandbox is torn down if the invoking process dies.
Requirements: Requires kernel support for unprivileged user namespaces (bwrap's only sandboxing model — setuid mode has been removed upstream). No root needed.
The sandbox root starts as an empty tmpfs — anything not explicitly bound is absent, including /bin and /lib unless you add the usr-merge symlinks.
Options are processed sequentially and later options can override earlier ones — argument order matters.
Latest release is v0.11.2; setuid bwrap is deprecated there and removed from current main, so do not design around a setuid-root bwrap binary.
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