Three independent hardenings, addressing a review finding that the
kernel and image build pipelines were relying on HTTPS alone for
artifact integrity.
scripts/make-generic-kernel.sh
- Fetch the detached PGP signature (linux-<ver>.tar.sign) alongside
the tarball and verify it with gpg before extraction. An isolated
$GNUPGHOME under the tempdir keeps the kernel signers out of the
invoking user's keyring.
- Import the three kernel.org release signing keys (Greg KH / Linus /
Sasha Levin) from keyserver.ubuntu.com, falling back to
keys.openpgp.org. Ubuntu comes first because keys.openpgp.org strips
unverified UIDs on upload, leaving gpg with UID-less keys it
refuses to trust.
- Require VALIDSIG (cryptographic proof) rather than GOODSIG
(printed even for expired keys) before proceeding. Verified
end-to-end against a clean tarball (accepts) and a byte-flipped
tampered copy (rejects with BADSIG).
- gpg + gpgv + xz added to the required-tools check.
images/golden/Dockerfile
- Pin Docker's apt signing key by fingerprint. After downloading
/etc/apt/keyrings/docker.asc we gpg --show-keys --with-colons it,
extract the fpr, and compare against the expected
9DC858229FC7DD38854AE2D88D81803C0EBFCD88. A tampered or swapped key
aborts the build before any apt repo metadata is fetched.
- Replace `curl https://mise.run | sh` with a pinned GitHub release
binary (mise v2026.4.18, linux-x64) verified against its published
sha256. Refuses to build on unknown architectures rather than
silently installing a binary we have no hash for.
- Add gnupg to the ESSENTIAL apt-get install so the fingerprint check
has gpg available.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Closes the full arc: banger kernel pull + image pull + vm create + vm ssh
now works end-to-end against docker.io/library/debian:bookworm with zero
manual image building.
Generic kernel:
- New scripts/make-generic-kernel.sh builds vmlinux from upstream
kernel.org sources using Firecracker's official minimal config
(configs/firecracker-x86_64-6.1.config). All critical drivers
(virtio_blk, virtio_net, ext4, vsock) compiled in — no modules,
no initramfs needed.
- Published as generic-6.12 in the catalog (kernels.thaloco.com).
- catalog.json updated with the new entry.
Direct-boot init= override (vm_lifecycle.go):
- For images without an initrd (direct-boot / OCI-pulled), banger now
passes init=/usr/local/libexec/banger-first-boot on the kernel
cmdline. The script runs as PID 1, mounts /proc /sys /dev /run,
checks for systemd — if present execs it immediately; if not
(container images), installs systemd-sysv + openssh-server via the
guest's package manager, then execs systemd.
- Also passes kernel-level ip= parameter via BuildBootArgsWithKernelIP
so the kernel configures the network interface before init runs
(container images don't ship iproute2, so the userspace bootstrap
script can't call ip(8)).
- Masks dev-ttyS0.device and dev-vdb.device systemd units that
otherwise wait 90s for udev events that never fire in Firecracker
guests started from container rootfses.
first-boot.sh rewritten as universal init wrapper:
- Works as PID 1 (mounts essential filesystems) OR as a systemd
oneshot (existing behavior).
- Installs both systemd-sysv AND openssh-server (container images
have neither).
- Dispatch updated: debian, alpine, fedora, arch, opensuse families
+ ID_LIKE fallback. All tests updated.
Opencode capability skip for direct-boot images:
- The opencode readiness check (WaitReady on vsock port 4096) now
returns nil for images without an initrd, since pulled container
images don't ship the opencode service. Without this, the VM
would be marked as error for lacking an opinionated add-on.
Docs: README and kernel-catalog.md updated to recommend generic-6.12
as the default kernel for OCI-pulled images. AGENTS.md notes the new
build script.
Verified live:
- banger kernel pull generic-6.12
- banger image pull docker.io/library/debian:bookworm --kernel-ref generic-6.12
- banger vm create --image debian-bookworm --name testbox --nat
- banger vm ssh testbox -- "id; uname -r; systemctl is-active banger-vsock-agent"
→ uid=0(root), kernel 6.12.8, Debian bookworm, vsock-agent active,
sshd running, SSH working.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
