Harden a bubblewrap sandbox with seccomp syscall filtering and network isolation for untrusted code
domain: github.com/containers/bubblewrap · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Add an empty network namespace so the sandbox cannot reach the host network: bwrap --unshare-net ...
Load a seccomp filter with --seccomp (via a file descriptor) to limit which syscalls the sandbox may run
At a minimum block the TIOCSTI ioctl in the filter, or pass --new-session
Filter D-Bus with xdg-dbus-proxy rather than binding the host socket directly to avoid command execution via systemd
Run the binary and verify it cannot reach the host network or signal host processes
Known gotchas
bwrap always creates a new mount namespace; the nodev default applies unless overridden
Binding a D-Bus socket plainly can allow command execution - use xdg-dbus-proxy to filter D-Bus communication
Apps that apply their own seccomp (e.g. browsers) may conflict if bwrap's filter disallows the seccomp syscall or the filter file is not available inside the sandbox
--unshare-net is required for network isolation; without it the sandbox shares the host network
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