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.
Separates what a VM IS (durable intent + identity + deterministic
derived paths — `VMRuntime`) from what is CURRENTLY TRUE about it
(firecracker PID, tap device, loop devices, dm-snapshot target — new
`VMHandles`). The durable state lives in the SQLite `vms` row; the
transient state lives in an in-memory cache on the daemon plus a
per-VM `handles.json` scratch file inside VMDir, rebuilt at startup
from OS inspection. Nothing kernel-level rides the SQLite schema
anymore.
Why:
Persisting ephemeral process handles to SQLite forced reconcile to
treat "running with a stale PID" as a first-class case and mix it
with real state transitions. The schema described what we last
observed, not what the VM is. Every time the observation model
shifted (tap pool, DM naming, pgrep fallback) the reconcile logic
grew a new branch. Splitting lets each layer own what it's good at:
durable records describe intent, in-memory cache + scratch file
describe momentary reality.
Shape:
- `model.VMHandles` = PID, TapDevice, BaseLoop, COWLoop, DMName,
DMDev. Never in SQLite.
- `VMRuntime` keeps: State, GuestIP, APISockPath, VSockPath,
VSockCID, LogPath, MetricsPath, DNSName, VMDir, SystemOverlay,
WorkDiskPath, LastError. All durable or deterministic.
- `handleCache` on `*Daemon` — mutex-guarded map + scratch-file
plumbing (`writeHandlesFile` / `readHandlesFile` /
`rediscoverHandles`). See `internal/daemon/vm_handles.go`.
- `d.vmAlive(vm)` replaces the 20+ inline
`vm.State==Running && ProcessRunning(vm.Runtime.PID, apiSock)`
spreads. Single source of truth for liveness.
- Startup reconcile: per running VM, load the scratch file, pgrep
the api sock, either keep (cache seeded from scratch) or demote
to stopped (scratch handles passed to cleanupRuntime first so DM
/ loops / tap actually get torn down).
Verification:
- `go test ./...` green.
- Live: `banger vm run --name handles-test -- cat /etc/hostname`
starts; `handles.json` appears in VMDir with the expected PID,
tap, loops, DM.
- `kill -9 $(pgrep bangerd)` while the VM is running, re-invoke the
CLI, daemon auto-starts, reconcile recognises the VM as alive,
`banger vm ssh` still connects, `banger vm delete` cleans up.
Tests added:
- vm_handles_test.go: scratch-file roundtrip, missing/corrupt file
behaviour, cache concurrency, rediscoverHandles prefers pgrep
over scratch, returns scratch contents even when process is
dead (so cleanup can tear down kernel state).
- vm_test.go: reconcile test rewritten to exercise the new flow
(write scratch → reconcile reads it → verifies process is gone →
issues dmsetup/losetup teardown).
ARCHITECTURE.md updated; `handles` added to Daemon field docs.
Both masks were added when the direct-boot path first landed for
container rootfses that didn't have anything mounted on /dev/vdb. The
golden image (and any pulled OCI image running under banger's
patchRootOverlay) has an /etc/fstab entry mounting /dev/vdb at /root —
masking dev-vdb.device makes systemd wait forever for a unit that can
never become active, and the work-disk mount never completes. dev-ttyS0
is a real serial console the image needs too. Drop both.
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>
vm.go (1529 LOC) splits into vm_create, vm_lifecycle, vm_set, vm_stats,
vm_disk, vm_authsync; firecracker/DNS/helpers stay in vm.go.
guest_sessions.go (1266 LOC) splits into session_controller,
session_lifecycle, session_attach, session_stream; scripts and helpers
stay in guest_sessions.go.
Mechanical move only. No behavior change. Adds doc.go and
ARCHITECTURE.md capturing subsystem map and current lock ordering as
the baseline for the upcoming subsystem extraction.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
