Previously the daemon socket, per-VM firecracker API socket, and vsock
socket were transiently world-exposed on hosts without XDG_RUNTIME_DIR:
the runtime directory landed in /tmp at 0755, Firecracker ran with
umask 000 (mode 0666 sockets), and only a follow-up chown/chmod in
EnsureSocketAccess tightened them. A local attacker could race into
bangerd.sock or the firecracker API socket during that window.
Three changes:
- internal/paths/paths.go: RuntimeDir is now created (and re-chmod'd if
stale) at 0700 unconditionally. When XDG_RUNTIME_DIR is unset and we
fall back to /tmp/banger-runtime-<uid>, Ensure() now verifies the
parent dir is owned by the current uid and 0700 mode — refusing to
place sockets inside a directory someone else created. Symlink swaps
rejected via Lstat.
- internal/firecracker/client.go: launch firecracker with umask 077
instead of umask 000 so the API socket is mode 0600 from birth. The
chown in fcproc.EnsureSocketAccess still transfers ownership from
root to the invoking user afterwards.
- internal/daemon/fcproc/fcproc.go: EnsureSocketDir now creates (and
re-chmod's) the runtime socket directory at 0700.
Tests cover the tightening path — an existing 0755 RuntimeDir is
re-chmod'd on Ensure.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Guest host-key verification was off in all three SSH paths:
* Go SSH (internal/guest/ssh.go) used ssh.InsecureIgnoreHostKey
* `banger vm ssh` passed StrictHostKeyChecking=no
+ UserKnownHostsFile=/dev/null
* `~/.ssh/config` Host *.vm shipped the same posture into the
user's global config
Now each path verifies against a banger-owned known_hosts file at
`~/.local/state/banger/ssh/known_hosts` with TOFU semantics:
* First dial to a VM pins the key.
* Subsequent dials require an exact match. A mismatch fails with
an explicit "possible MITM" error.
* `vm delete` removes the entries so a future VM reusing the IP
or name re-pins cleanly.
* The user's `~/.ssh/known_hosts` is untouched.
Changes:
internal/guest/known_hosts.go (new) — OpenSSH-compatible parser,
TOFUHostKeyCallback, RemoveKnownHosts. Process-wide mutex
around the file.
internal/guest/ssh.go — Dial and WaitForSSH grew a knownHostsPath
parameter threaded through the callback. Empty path keeps the
insecure callback (tests + throwaway tools only; documented).
internal/daemon/{guest_sessions,session_attach,session_lifecycle,
session_stream}.go — call sites pass d.layout.KnownHostsPath.
internal/daemon/ssh_client_config.go — the ~/.ssh/config Host *.vm
block now points at banger's known_hosts and uses
StrictHostKeyChecking=accept-new. Missing path → fail closed.
internal/daemon/vm_lifecycle.go — deleteVMLocked drops known_hosts
entries for the VM's IP and DNS name via removeVMKnownHosts.
internal/cli/banger.go — sshCommandArgs swaps StrictHostKeyChecking
no + /dev/null for banger's file + accept-new. Path resolution
failure falls through to StrictHostKeyChecking=yes.
internal/paths/paths.go — Layout gains SSHDir + KnownHostsPath;
Ensure creates SSHDir at 0700.
Tests (internal/guest/known_hosts_test.go): pin on first use, accept
matching key on second dial, reject mismatch, empty path skips
checking, RemoveKnownHosts drops the entry, re-pin works after
remove. Existing daemon + cli tests updated to assert the new
posture and regression-guard against the old flags.
Live verified: vm run writes the pin to banger's known_hosts at 0600
inside a 0700 dir; banger vm ssh + ssh root@<vm>.vm both succeed
using the pin; vm delete clears it.
New internal/imagepull/ subpackage. Three concerns, each
independently testable:
Pull (imagepull.go):
- github.com/google/go-containerregistry's remote.Image with the
linux/amd64 platform pinned. Anonymous pulls only for v1.
- Layer blobs cached on disk via cache.NewFilesystemCache under
<cacheDir>/blobs/sha256/<hex> — OCI-standard layout so
skopeo/crane could co-exist later.
- Eagerly touches every layer once so network errors surface at
Pull time, not deep in Flatten.
Flatten (flatten.go):
- Replays layers oldest-first into destDir.
- Whiteout-aware: .wh.<name> deletes the named entry,
.wh..wh..opq wipes the parent directory's contents from prior
layers.
- Path-traversal hardening mirrored from kernelcat extractTar:
reject .., absolute paths, and symlinks/hardlinks whose
resolved target escapes destDir.
- Handles tar.TypeReg, TypeDir, TypeSymlink, TypeLink. Skips
device/fifo nodes silently (need privilege; udev/devtmpfs
handles them in the guest).
BuildExt4 (ext4.go):
- Truncates outFile to sizeBytes, then runs `mkfs.ext4 -F -d
<srcDir> -E root_owner=0:0`. No mount, no sudo, no loopback.
- 64 MiB floor; callers handle real sizing with content-aware
headroom.
- File ownership in the resulting ext4 reflects srcDir's on-disk
ownership — runner's uid/gid since extraction was unprivileged.
Documented in package doc as a Phase A v1 limitation; Phase B
will add a debugfs- or tar2ext4-based ownership fixup.
paths.Layout gains OCICacheDir at $XDG_CACHE_HOME/banger/oci/,
ensured at startup alongside the other dirs.
Tests use go-containerregistry's in-process registry to push and
pull synthetic multi-layer images. Cover: layer caching round-trip,
whiteout + opaque-marker handling, path-traversal rejection, unsafe
symlink rejection, real mkfs.ext4 round-trip (skipped if mkfs.ext4
absent), and tiny-size rejection.
go-containerregistry v0.21.5 added as a direct dep, plus its
transitive closure (containerd/stargz, opencontainers/go-digest,
docker/cli config helpers, etc).
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>
Hard-cut banger away from source-checkout runtime bundles as an implicit source of\nimage and host defaults. Managed images now own their full boot set,\nimage build starts from an existing registered image, and daemon startup\nno longer synthesizes a default image from host paths.\n\nResolve Firecracker from PATH or firecracker_bin, make SSH keys config-owned\nwith an auto-managed XDG default, replace the external name generator and\npackage manifests with Go code, and keep the vsock helper as a companion\nbinary instead of a user-managed runtime asset.\n\nUpdate the manual scripts, web/CLI forms, config surface, and docs around\nthe new build/manual flow and explicit image registration semantics.\n\nValidation: GOCACHE=/tmp/banger-gocache go test ./..., bash -n scripts/*.sh,\nand make build.
Separate tracked source from generated artifacts so the repo root stops accumulating helper scripts, manifests, and local runtime outputs.
Move manual shell entrypoints under scripts/, manifests under config/, and the Firecracker API reference under docs/reference/. Make build and runtimebundle now target build/bin, build/runtime, and build/dist as the canonical source-checkout paths.
Update runtime discovery, helper scripts, tests, and docs to follow the new layout while keeping legacy source-checkout runtime fallbacks for existing local bundles during migration.
Validated with bash -n on the moved scripts, make build, and GOCACHE=/tmp/banger-gocache go test ./....
Stop assuming one workstation layout for runtime artifacts, mapdns, and host tooling. The daemon and shell helpers now use portable mapdns configuration, and runtime bundles can carry bundle.json metadata for their default kernel, initrd, modules, rootfs, and helper paths.
Load bundle metadata through config with a legacy layout fallback, thread mapdns_bin/mapdns_data_file through the Go and shell paths, and add command-scoped preflight checks for VM start, NAT, image build, work-disk resize, and SSH so missing tools or artifacts fail with actionable errors.
Update the runtime-bundle manifest, docs, and tests to match the new model. Verified with go test ./..., make build, and bash -n customize.sh interactive.sh dns.sh make-rootfs.sh verify.sh.
Stop treating Firecracker, kernels, modules, and guest images as tracked source files. Source checkouts now resolve runtime assets from ./runtime, while installed binaries keep using ../lib/banger.
Add a small runtimebundle helper plus runtime-bundle.toml so make can bootstrap, package, and install a runtime bundle with checksum validation. Update the shell helpers and daemon path hints to fail clearly when the bundle is missing instead of assuming repo-root artifacts.
This removes the tracked runtime blobs from HEAD in favor of an ignored local runtime/ tree. Verified with go test ./..., make build, bash -n on the shell helpers, make -n install, and a temporary package/fetch smoke test. The manifest URL/SHA still need a published bundle before fresh clones can bootstrap, and history rewrite remains a separate rollout step.
Fix the misleading make install path where banger and bangerd still depended on a repo checkout for Firecracker, guest artifacts, image builds, and the SSH key.
Replace repo-root inference with an explicit runtime bundle model: resolve a runtime_dir from env/config/install layout, derive concrete artifact paths from it, and update the daemon, CLI, and image-build flow to use those paths. Keep repo_root only as an explicit compatibility alias instead of auto-detecting it.
Teach customize.sh to run from a read-only bundled runtime tree while writing transient state under XDG/BANGER_STATE_DIR, and make make install copy the runtime assets into PREFIX/lib/banger so installed binaries stay usable outside the repo.
Validate with go test ./..., make build, bash -n customize.sh, and make install DESTDIR=/tmp/banger-install PREFIX=/usr. An out-of-repo installed-binary smoke test was attempted, but this sandbox blocked bangerd from binding its Unix socket (setsockopt: operation not permitted).
Replace the shell-only user workflow with `banger` and `bangerd`: Cobra commands, XDG/SQLite-backed state, managed VM and image lifecycle, and a Bubble Tea TUI for browsing and operating VMs.\n\nKeep Firecracker orchestration behind the daemon so VM specs become persistent objects, and add repo entrypoints for building, installing, and documenting the new flow while still delegating rootfs customization to the existing shell tooling.\n\nHarden the control plane around real usage by reclaiming Firecracker API sockets for the user, restarting stale daemons after rebuilds, and returning the correct `vm.create` payload so the CLI and TUI creation flow work reliably.\n\nValidation: `go test ./...`, `make build`, and a host-side smoke test with `./banger vm create --name codex-smoke`.
