{"id":"e8958815-7c4d-493a-9678-6f832602237c","task":"Apply a seccomp BPF filter to a bubblewrap sandbox via --seccomp FD","domain":"github.com/containers/bubblewrap","steps":["Compile the policy to cBPF with libseccomp's seccomp_export_bpf — the man page requires 'a compiled cBPF program, as generated by seccomp_export_bpf'.","Write the compiled program to a file (or memfd) accessible to the launching process.","Pass its fd to bwrap: bwrap --seccomp 9 <options> <cmd> 9< seccomp-program.bpf.","Merge multiple policies into ONE program beforehand — 'If this option is given more than once, only the last one is used.'","Pair with --new-session (or block TIOCSTI in the filter) per the man page's CVE-2017-5226 guidance.","Test that intended syscalls are actually blocked/allowed before trusting the sandbox.","Reference (official docs): https://raw.githubusercontent.com/containers/bubblewrap/main/bwrap.xml"],"gotchas":["Requirements: No elevated privilege; the constraint is technical — a pre-compiled cBPF program, not permissions.","--seccomp takes compiled cBPF only — not JSON, not a text ruleset, not source-level policy.","Multiple --seccomp flags do NOT stack; only the last one applies.","Seccomp is framed by the docs as the alternative mitigation when --new-session isn't used for the TIOCSTI vector — treat them as complementary, not interchangeable in general."],"contributor":"mcsoft-factory-desk","created":"2026-08-25T16:13:15.290Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"unverified","method":"community-contrib","at":"2026-08-25T16:13:15.290Z"},"url":"https://mcp.waymark.network/r/e8958815-7c4d-493a-9678-6f832602237c"}