feat(sandbox): wire selective network allowlist into BashTool (#10)#144
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BashTool now routes commands through spawnNetworkSandbox when network.allowedDomains is a non-empty allowlist on Linux. If the slirp sandbox can't be set up (e.g. the DNS proxy can't bind 127.0.0.1:53), it FAILS CLOSED — re-runs under deny-all-net with a clear note — rather than running unrestricted. Background commands always fail closed (the slirp helper can't safely outlive the turn). - netns.ts: add pure helpers needsNetworkSandbox() (linux + enabled + non-empty allowlist) and denyAllNetwork() (fail-closed config). - bash.ts: foreground net path (capture/timeout/abort via the handle), fail-closed fallback, background deny-all; shared summarize() helper. - Tests: netns.test.ts (decision + config helpers, runs everywhere) + bash.test.ts wiring tests using an injected fake spawner (net path, fail-closed fallback, background) — no real bwrap needed. - docs/security-model.md: document the Linux allowlist, its DNS-name threat model, the :53 requirement, and the fail-closed behavior. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Completes #10 by making the selective per-domain network allowlist (mechanism landed in #143) actually used by the Bash tool.
What
BashToolnow routes a command throughspawnNetworkSandboxwhensandbox.network.allowedDomainsis a non-empty allowlist on Linux. Otherwise the existingwrapBashCommandpath is used (deny-all-net via--unshare-netfor[], full network forundefined, macOS sandbox-exec, etc.).Fail closed: if the slirp sandbox can't be set up — most commonly because the allowlisting DNS proxy can't bind
127.0.0.1:53(privileged port) — BashTool re-runs the command under deny-all-net with a clear note, rather than running it unrestricted. Background commands always fail closed (the slirp helper can't safely outlive the turn).Changes
netns.ts— pure helpersneedsNetworkSandbox()anddenyAllNetwork().bash.ts— foreground net path (capture / timeout / abort driven by the handle), the fail-closed fallback, background deny-all; a sharedsummarize()helper for consistent output.netns.test.ts(decision + config helpers, runs everywhere) andbash.test.tswiring tests via an injected fake spawner (happy path, fail-closed fallback, background) — no real bwrap required. The real end-to-end path stays covered bynetns-integration.test.tson the Linux CI job.docs/security-model.md— documents the Linux allowlist, its DNS-name threat model, the:53requirement, and the fail-closed behavior.Limits (documented)
DNS-name allowlisting — a raw-IP dial bypasses it (adequate for git/npm/pip-over-https). Per-domain allowlisting is Linux-only (macOS SBPL has no usable remote-host predicate). Where
:53isn't bindable, it fails closed to deny-all-net.🤖 Generated with Claude Code