fix(krun): air-gap guests by default; opt-in TSI inet hijack#53
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toksdotdev merged 1 commit intokrunfrom Apr 30, 2026
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fix(krun): air-gap guests by default; opt-in TSI inet hijack#53toksdotdev merged 1 commit intokrunfrom
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when no virtio-net device was configured, configure_vsock auto-enabled TsiFlags::HIJACK_INET so the guest's inet socket calls were transparently bridged to the host through vsock. that silently defeated air-gap setups: the guest had no network interface, yet its tcp/udp traffic still reached the outside world. flipped the default so guests with no virtio-net are air-gapped, and added MachineBuilder::enable_inet_hijack(bool) for callers that still want the TSI fallback. reported in superradcompany/microsandbox#645. BREAKING CHANGE: callers that previously relied on the implicit TSI fallback (no virtio-net configured) must now call .machine(|m| m.enable_inet_hijack(true)) to keep that behavior.
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bumped all msb_krun_* workspace crates and their internal path-dependency version refs from 0.1.11 to 0.1.12, and refreshed both lockfiles. the libkrun C-API crate (1.17.3) and the example crates are unchanged. changes since 0.1.11: - fix(krun): air-gap guests by default; opt-in TSI inet hijack (#53)
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problem
when no virtio-net device was configured,
configure_vsockauto-enabledTsiFlags::HIJACK_INETso the guest's inet socket calls were transparently bridged to the host through vsock. that's a sensible default for "no network attached, give me something usable," but it silently defeated true air-gap setups: the guest had no network interface, yet its tcp/udp traffic still reached the outside world.reported downstream in superradcompany/microsandbox#645 where
msb run --no-net ... nc 1.1.1.1 80returned a cloudflare 301 even thoughip ashowed onlylo.fix
flipped the default so guests with no virtio-net are air-gapped, and added
MachineBuilder::enable_inet_hijack(bool)for callers that still want the TSI fallback. covered by unit tests.breaking: callers that previously relied on the implicit TSI fallback (no virtio-net configured) must now call
.machine(|m| m.enable_inet_hijack(true))to keep that behavior.test plan
cargo build -p msb_krun(no features)cargo build -p msb_krun --features netcargo test -p msb_kruncargo test -p msb_krun --features net api::vmcargo clippy -p msb_krun --features net --tests -- -D warningscargo fmt -p msb_krun --check