Files
felhom-controller/controller/internal/offsiteapply/offsiteapply_test.go
T
admin 9a34887acc harden offsite apply-bridge: pin verified host key on the install/verify sessions (no TOFU)
The SSHCopyIDInstaller used StrictHostKeyChecking=accept-new on the ssh-copy-id
and sftp-verify connections, so even though the bridge verifies the box host-key
fingerprint against the hub descriptor BEFORE installing, the actual install
connection was not pinned to that verified key — a MITM could substitute a
different key in the gap between the scan and the install (TOCTOU).

Now the bridge threads the scanner-verified known_hosts line into KeyInstaller,
which writes it to a temp known_hosts and connects with StrictHostKeyChecking=yes
+ UserKnownHostsFile — the install/verify sessions refuse any key but the one the
bridge already matched. Empty known_hosts now refuses to install.

Test asserts the installer receives the pinned known_hosts; red-proofed by passing
an empty line (the pre-fix TOFU shape) → test fails. Addresses the security-review
"host-key TOFU after verify" finding on internal/offsiteapply/seams.go.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6
2026-07-09 19:24:17 +02:00

193 lines
6.0 KiB
Go

package offsiteapply
import (
"bytes"
"context"
"errors"
"log"
"os"
"path/filepath"
"strings"
"testing"
"gitea.dooplex.hu/admin/felhom-controller/internal/config"
)
// --- fakes ---
type fakeConsumer struct {
pw string
err error
calls int
panics bool
}
func (f *fakeConsumer) Consume(_ context.Context) (string, error) {
if f.panics {
panic("consume must NOT be called (idempotent no-op)")
}
f.calls++
return f.pw, f.err
}
type fakeScanner struct {
fp, line string
err error
}
func (f *fakeScanner) Scan(_ context.Context, _ string, _ int) (string, string, error) {
return f.fp, f.line, f.err
}
type fakeKeyGen struct{ priv, pub string }
func (f *fakeKeyGen) Generate() (string, string, error) { return f.priv, f.pub, nil }
type fakeInstaller struct {
err error
calls int
gotPub string
gotPriv string
gotPw string
gotKnownHost string
}
func (f *fakeInstaller) Install(_ context.Context, _, _ string, _ int, password, privPEM, pub, knownHosts string) error {
f.calls++
f.gotPub, f.gotPriv, f.gotPw, f.gotKnownHost = pub, privPEM, password, knownHosts
return f.err
}
type fakeEnabler struct {
err error
calls int
gotHost string
gotKnownHost string
gotPriv string
}
func (f *fakeEnabler) ConfigureOffbox(_ context.Context, host, _ string, _ int, _, privPEM, knownHosts string) error {
f.calls++
f.gotHost, f.gotKnownHost, f.gotPriv = host, knownHosts, privPEM
return f.err
}
func newBridge(t *testing.T, o config.OffsiteConfig) (*Bridge, *fakeConsumer, *fakeInstaller, *fakeEnabler, *bytes.Buffer) {
t.Helper()
cfg := &config.Config{}
cfg.Offsite = o
cons := &fakeConsumer{pw: "the-transient-pw"}
inst := &fakeInstaller{}
en := &fakeEnabler{}
var logbuf bytes.Buffer
b := &Bridge{
Cfg: cfg,
Consumer: cons,
Scanner: &fakeScanner{fp: "SHA256:goodfp", line: "[h]:23 ssh-ed25519 AAAAKEY"},
KeyGen: &fakeKeyGen{priv: "PRIVPEM", pub: "ssh-ed25519 AAAAPUB felhom"},
Installer: inst,
Enabler: en,
MarkerPath: filepath.Join(t.TempDir(), "offbox", "applied_marker"),
Logger: log.New(&logbuf, "", 0),
}
return b, cons, inst, en, &logbuf
}
func goodOffsite() config.OffsiteConfig {
return config.OffsiteConfig{Enabled: true, Type: "shared", Host: "h", User: "u", Port: 23, RepoPath: "/home/felhom-repo", HostFingerprint: "SHA256:goodfp"}
}
// Scenario A — full apply: consume → verify-pin → install → configure offbox → marker persisted; pw not logged.
func TestBridge_AppliesEndToEnd(t *testing.T) {
b, cons, inst, en, logbuf := newBridge(t, goodOffsite())
if err := b.Reconcile(context.Background()); err != nil {
t.Fatalf("reconcile: %v", err)
}
if cons.calls != 1 {
t.Fatalf("consume calls = %d, want 1", cons.calls)
}
if inst.calls != 1 || inst.gotPw != "the-transient-pw" || inst.gotPub == "" {
t.Fatalf("installer not called with pw+pub: %+v", inst)
}
if inst.gotKnownHost != "[h]:23 ssh-ed25519 AAAAKEY" {
t.Fatalf("installer must receive the scanner-verified known_hosts to pin (no TOFU), got %q", inst.gotKnownHost)
}
if en.calls != 1 || en.gotHost != "h" || en.gotKnownHost != "[h]:23 ssh-ed25519 AAAAKEY" || en.gotPriv != "PRIVPEM" {
t.Fatalf("enabler not called with the pinned known_hosts + key: %+v", en)
}
if b.readMarker() != descriptorHash(b.Cfg.Offsite) {
t.Fatal("marker not persisted after a successful apply")
}
if strings.Contains(logbuf.String(), "the-transient-pw") {
t.Fatal("the one-time password LEAKED into a log line")
}
}
// Scenario B — host-key mismatch → refuse: no consume, no install, no configure, no marker.
func TestBridge_HostKeyMismatchRefuses(t *testing.T) {
b, cons, inst, en, _ := newBridge(t, goodOffsite())
b.Scanner = &fakeScanner{fp: "SHA256:ATTACKER", line: "[h]:23 ssh-ed25519 EVIL"}
err := b.Reconcile(context.Background())
if err == nil || !strings.Contains(err.Error(), "MISMATCH") {
t.Fatalf("mismatch must refuse, got %v", err)
}
if cons.calls != 0 || inst.calls != 0 || en.calls != 0 {
t.Fatalf("nothing may proceed on a host-key mismatch: cons=%d inst=%d en=%d", cons.calls, inst.calls, en.calls)
}
if b.readMarker() != "" {
t.Fatal("no marker may be written on a mismatch")
}
}
// Scenario C — idempotent: marker already matches → no-op, consume is NOT called.
func TestBridge_IdempotentNoReconsume(t *testing.T) {
b, cons, inst, en, _ := newBridge(t, goodOffsite())
cons.panics = true // Consume must not be called
// pre-seed the marker with the current descriptor hash
_ = os.MkdirAll(filepath.Dir(b.MarkerPath), 0o700)
if err := os.WriteFile(b.MarkerPath, []byte(descriptorHash(b.Cfg.Offsite)), 0o600); err != nil {
t.Fatal(err)
}
if err := b.Reconcile(context.Background()); err != nil {
t.Fatalf("idempotent reconcile must be a clean no-op, got %v", err)
}
if cons.calls != 0 || inst.calls != 0 || en.calls != 0 {
t.Fatal("an already-applied descriptor must be a full no-op")
}
}
// Scenario D — install fails → fail-safe: marker NOT persisted, offbox NOT configured, loud log.
func TestBridge_InstallFailIsFailSafe(t *testing.T) {
b, cons, inst, en, logbuf := newBridge(t, goodOffsite())
inst.err = errors.New("ssh-copy-id refused")
err := b.Reconcile(context.Background())
if err == nil {
t.Fatal("install failure must error")
}
if en.calls != 0 {
t.Fatal("offbox must NOT be configured when install fails")
}
if b.readMarker() != "" {
t.Fatal("marker must NOT be persisted on a failed apply (fail-safe)")
}
if cons.calls != 1 {
t.Fatal("the password was consumed (spent) before install")
}
if !strings.Contains(logbuf.String(), "password is spent") {
t.Fatal("a consumed-but-failed install must log the loud 'password is spent' signal")
}
}
// Disabled → no-op (no consume/install/configure).
func TestBridge_DisabledNoOp(t *testing.T) {
o := goodOffsite()
o.Enabled = false
b, cons, inst, en, _ := newBridge(t, o)
if err := b.Reconcile(context.Background()); err != nil {
t.Fatal(err)
}
if cons.calls+inst.calls+en.calls != 0 {
t.Fatal("disabled offsite must be a no-op")
}
}