Both Fetch flows previously streamed resp.Body straight into
zstd → tar → on-disk extractor with the SHA256 check tacked on at
the END. A bad mirror or an attacker that's compromised the catalog
host could ship a multi-gigabyte tarball, watch banger expand it to
disk, and only THEN see the helpful "sha256 mismatch" message —
having already filled the host filesystem.
Reorder the operations: stage the compressed tarball to a temp file
under the destination directory through an io.LimitReader (cap +1
bytes), hash on the way in, refuse to decompress if either the cap
trips or the SHA mismatches. Worst-case disk use is bounded by the
cap, not by the source.
Cap is exposed as a package var (MaxFetchedBundleBytes,
MaxFetchedKernelBytes) so callers can tune per-deployment and tests
can squeeze it down to provoke the rejection. Default 8 GiB —
generous enough for a 4 GiB rootfs (which compresses to ~1-2 GiB),
tight enough to make a "fill the host disk" attack expensive.
The temp file lives in the destination dir so extraction stays on
the same filesystem and we don't pay for cross-FS rename. defer
os.Remove cleans up; the existing per-package cleanup() handler
still removes any partial extraction on hash mismatch / extraction
failure.
Tests: each package gets a TestFetchRejectsOversizedTarballBefore
Extraction that sets the cap to 64 bytes, points Fetch at a multi-KB
tarball, and asserts (a) error mentions "cap", (b) destination dir
is left clean (no leaked rootfs / manifest / kernel tree). All
existing tests still pass — happy path, hash mismatch, missing
files, path traversal, HTTP error, etc.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The golden-image Dockerfile + catalog pipeline replaces the entire
manual rootfs-build stack. With that shipped, the per-distro shell
flows are dead code.
Removed:
- scripts/customize.sh, scripts/interactive.sh, scripts/verify.sh
- scripts/make-rootfs{,-void,-alpine}.sh
- scripts/register-{void,alpine}-image.sh
- scripts/make-{void,alpine}-kernel.sh
- internal/imagepreset/ (only consumer was `banger internal packages`,
which fed customize.sh)
- examples/{void,alpine}.config.toml
- Makefile targets: rootfs, rootfs-void, rootfs-alpine, void-kernel,
alpine-kernel, void-register, alpine-register, void-vm, alpine-vm,
verify-void, verify-alpine, plus the ALPINE_RELEASE / *_IMAGE_NAME
/ *_VM_NAME variables
The void-6.12 kernel catalog entry is also gone — golden image pairs
with generic-6.12 and nothing else in the catalog depended on it.
Consolidated: imagemgr now holds the small DebianBasePackages list +
package-hash helper inline, so the `image build --from-image` flow
(still supported) no longer pulls from a separate imagepreset package.
Net: 3,815 lines deleted, 59 added. No runtime functionality removed
beyond the `banger internal packages` subcommand (hidden, used only
by the deleted customize.sh).
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>
Container (and kernel) layers routinely ship symlinks with absolute
targets — /usr/bin/mawk, /lib/modules/<ver>/build, etc. Those are
interpreted relative to the rootfs at runtime (`/` inside the VM),
not against the host filesystem, so they are rooted inside dest by
construction and need no escape check at write time.
The previous logic resolved absolute Linknames literally (against
the host root), compared to the staging dir, and rejected everything
that didn't happen to live under it. That made `banger image pull
docker.io/library/debian:bookworm` fail on the very first symlink
("etc/alternatives/awk -> /usr/bin/mawk").
Relative targets still get the traversal check — a relative
Linkname with ../s can genuinely escape dest at write time even if
in-VM resolution would be safe — so the defense against malicious
relative chains is intact.
Tests:
- TestFlattenAcceptsAbsoluteSymlink replaces the old overly-strict
test, using the exact etc/alternatives/awk -> /usr/bin/mawk case
that broke debian:bookworm.
- TestFlattenRejectsRelativeSymlinkEscape confirms relative-with-
traversal is still rejected with the same "unsafe symlink"
error.
Same fix applied in internal/kernelcat/fetch.go for consistency;
future kernel bundles with absolute symlinks in the modules tree
would otherwise hit the same wall.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Introduces the headline feature of the kernel catalog: pulling a kernel
bundle over HTTP without any local build step.
Catalog format (internal/kernelcat/catalog.go):
- Catalog { Version, Entries } + CatEntry { Name, Distro, Arch,
KernelVersion, TarballURL, TarballSHA256, SizeBytes, Description }.
- catalog.json is embedded via go:embed and ships with each banger
binary. It starts empty (Phase 5's CI pipeline will populate it).
- Lookup(name) returns the matching entry or os.ErrNotExist.
Fetch (internal/kernelcat/fetch.go):
- HTTP GET with streaming SHA256 over the response body.
- zstd-decode (github.com/klauspost/compress/zstd) -> tar extract into
<kernelsDir>/<name>/.
- Hardens against path-traversal tarball entries (members whose
normalised path escapes the target dir, and unsafe symlink
targets) and sha256-mismatch downloads; any failure removes the
partially-populated target dir.
- Regular files, directories, and safe symlinks are supported; other
tar types (hardlinks, devices, fifos) are silently skipped.
- After extraction, recomputes sha256 over the on-disk vmlinux and
writes the manifest with Source="pull:<url>".
Daemon methods (internal/daemon/kernels.go):
- KernelPull(ctx, {Name, Force}) - lookup in embedded catalog, refuse
overwrite unless Force, delegate to kernelcat.Fetch.
- KernelCatalog(ctx) - return the embedded catalog annotated per-entry
with whether it has been pulled locally.
RPC: kernel.pull, kernel.catalog dispatch cases.
CLI:
- `banger kernel pull <name> [--force]`.
- `banger kernel list --available` prints the catalog with a
pulled/available STATE column and a human-readable size.
Tests: fetch round-trip (extract + manifest + sha256), sha256 mismatch
rejection with cleanup, missing-vmlinux rejection, path-traversal
rejection, HTTP error propagation, catalog parsing, lookup,
pulled-status reconciliation. All 20 packages green.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
`banger kernel import <name> --from <dir>` copies a staged kernel
bundle into the local catalog. <dir> is the output of
`make void-kernel` or `make alpine-kernel` (build/manual/void-kernel/
or build/manual/alpine-kernel/).
kernelcat.DiscoverPaths locates artifacts under <dir>:
1. Prefers metadata.json (written by make-void-kernel.sh).
2. Falls back to globbing: boot/vmlinux-* or vmlinuz-* (Alpine
fallback), boot/initramfs-*, lib/modules/<latest>.
The daemon's KernelImport copies kernel + optional initrd via
system.CopyFilePreferClone and modules via system.CopyDirContents
(no-sudo mode — catalog lives under ~/.local/state), computes SHA256
over the kernel, and writes the manifest via kernelcat.WriteLocal.
While wiring this up, fixed a latent bug in system.CopyDirContents:
filepath.Join(sourceDir, ".") silently drops the trailing dot, so
`cp -a source source/contents target/` was copying the whole source
directory (including its basename) instead of just its contents.
Replaced the join with a manual "/." suffix. imagemgr.StageBootArtifacts
(the only existing caller) silently benefits.
scripts/register-void-image.sh and scripts/register-alpine-image.sh
are rewritten to use `banger kernel import … && banger image register
--kernel-ref …` instead of the find-and-pass-paths dance. Preserves
the same user-facing commands and env vars.
Tests cover: metadata.json preference, glob fallback, Alpine vmlinuz
fallback, kernel-missing error, round-trip copy into the catalog, and
the --from required flag.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Introduces a read/write kernel catalog on disk without any network
dependency, so later phases (image register --kernel-ref, import, pull)
can build on a working foundation.
Layout: adds KernelsDir to paths.Layout, ensured under
~/.local/state/banger/kernels/. Each cataloged kernel lives at
<KernelsDir>/<name>/ with a manifest.json alongside vmlinux and optional
initrd.img / modules/.
New internal/kernelcat package owns the disk format:
- Entry (Name, Distro, Arch, KernelVersion, SHA256, Source, ImportedAt)
- ValidateName (alphanumeric + dots/hyphens/underscores, no traversal)
- ReadLocal / ListLocal / WriteLocal / DeleteLocal
- SumFile helper
The daemon exposes three RPC methods dispatched in daemon.go:
kernel.list, kernel.show, kernel.delete. Implementations live in a new
internal/daemon/kernels.go and are thin wrappers over kernelcat using
d.layout.KernelsDir.
CLI: new top-level `banger kernel` with list / show / rm subcommands
mirroring the image-command pattern (ensureDaemon, RPC call, table or
JSON output). No sudo required — kernel ops are user-space only.
Users can now manually populate ~/.local/state/banger/kernels/<name>/
and see it via `banger kernel list`. Phase 2 wires --kernel-ref into
image register; Phase 3 adds `banger kernel import`; Phase 4 adds
remote pulls.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
