Allow disabling melange runner network (capabilities.networking)#2546
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The capabilities.networking flag was only wired into the bubblewrap runner. On docker and qemu it was silently ignored, so a config with networking: false still ran build/test steps with full network access (docker is the default runner on macOS). - docker: set HostConfig.NetworkMode to "none" when networking is disabled (loopback only, no route off-box). - qemu: add SLIRP restrict=on to the guest netdev when networking is disabled. This isolates the guest from the host and the outside world while leaving the hostfwd SSH control channel intact. Extract dockerNetworkMode and qemuNetdevArgs helpers and add unit tests covering the network decision for all three runners.
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Summary
Add an optional
capabilities.networkingboolean to melange YAML so callers candisable network access in the build/test runner sandbox. Honored by all three
runners: bubblewrap, docker, and qemu.
Motivation (security)
melange currently always enables networking for the sandbox runner, which makes
it harder to build packages in network-restricted environments. Disabling
networking at the runner boundary reduces supply-chain risk by preventing
exfiltration and remote fetches during build/test steps.
Behavior
Backward compatible. When
capabilities.networkingis omitted, melange keepsthe current behavior (network enabled). When set to
false, melange disablesnetwork in the runner sandbox:
--unshare-net(new network namespace, loopback only)NetworkMode=none(loopback only, no route off-box)restrict=on(guest isolated from host and the outside world,while the hostfwd SSH control channel melange uses to drive the guest stays
intact)
Usage
Tests
Unit tests cover the network decision for each runner (
dockerNetworkMode,qemuNetdevArgs, and the bubblewrap arg construction). Also verifiedend-to-end: a probe package whose pipeline curls an external host fails the
build when reachability does not match the flag, run across all three runners.
go test ./...