fix: CNI guest MAC for macOS VMs

README.md

@@ -9,7 +9,7 @@ macOS VM engine for x86 Linux/KVM, built on [cocoon](https://github.com/cocoonst
 - **Fully-automated macOS install** — a GitHub Action boots OpenCore, erases APFS, drives the installer by OCR, and publishes a golden qcow2 (Tahoe 26 / Sequoia 15) to ghcr; the `:26` image is **SSH-ready** (`cocoon`/`cocoon`)
 - **Docker-like CLI** — `create`, `run`, `start`, `stop`, `list`, `inspect`, `console`, `rm`, `snapshot`, `restore`, `clone`
 - **Parallel Range image pull** — the multi-GB qcow2 is pulled in 8 concurrent HTTP Range chunks with an sha256 digest check (oras-go for auth; no `oras` binary needed)
-- **Per-VM Apple identity** — `--random-smbios` injects a unique serial/MLB/UUID/ROM (guest MAC = ROM) into a per-VM OpenCore, so clones never share a serial
+- **Per-VM Apple identity** — `--random-smbios` injects a unique serial/MLB/UUID/ROM into a per-VM OpenCore; the ROM is the guest MAC outside CNI, so clones never share a serial
 - **CNI networking with TC redirect** — `--net cni` joins cocoon's forwarding plane so the guest DHCPs a real LAN IP; also user/tap/bridge; reachable VNC (launch-scoped, password-gated on CNI)
 - **Snapshot, clone & data disks** — offline qcow2-internal snapshots, CoW clones that cold-boot a fresh Apple identity, and up to 4 extra AHCI data disks
 - **Intel & AMD, built on cocoon** — one boot recipe boots both hosts; imports cocoon's `cloudimg` store, `network` plane, and copy-on-write conventions

cmd/vm/lifecycle.go

@@ -154,7 +154,7 @@ func (h *Handler) create(cmd *cobra.Command, image string) (*record, error) {
 	if r.DataDisks, err = createDataDisks(ctx, dir, diskSpecs); err != nil {
 		return nil, err
 	}
-	// OpenCore before networking: a random SMBIOS sets r.MAC = ROM, which prepareNet keeps as the guest MAC.
+	// OpenCore seeds the default guest MAC from ROM before network provisioning.
 	randomSMBIOS, _ := cmd.Flags().GetBool("random-smbios")
 	if err = prepareOpenCore(ctx, dir, oc, randomSMBIOS, r); err != nil {
 		return nil, err

cmd/vm/net_linux.go

@@ -80,8 +80,10 @@ func provisionNet(cmd *cobra.Command, r *record) (tap, netns, mac string, err er
 	if len(cfgs) == 0 {
 		return "", "", "", errors.New("network add returned no NIC")
 	}
-	// SMBIOS ROM wins as the guest MAC; cocoon's generated MAC is only a fallback
-	mac = cmp.Or(r.MAC, cfgs[0].MAC)
+	mac = cfgs[0].MAC
+	if r.NetMode != netCNI {
+		mac = cmp.Or(r.MAC, mac)
+	}
 	return cfgs[0].TAP, nsPath, mac, nil
 }
 

cmd/vm/utils.go

@@ -99,9 +99,7 @@ func applyNet(cmd *cobra.Command, r *record) error {
 	if err != nil {
 		return err
 	}
-	if r.MAC == "" {
-		r.MAC = mac
-	}
+	r.MAC = mac
 	if netTap != "" {
 		r.Tap, r.Netns, r.TapOwned = netTap, netns, userTap == ""
 	}

docs/index.md

@@ -46,7 +46,7 @@ cocoon-macos CLI ──► image: pull the golden macOS qcow2 from ghcr (paralle
 - **COW overlays** — an instant copy-on-write clone of the immutable golden base
   per VM
 - **Per-VM Apple identity** — `--random-smbios` injects a unique serial/MLB/UUID/ROM
-  (guest MAC = ROM) into a per-VM OpenCore, so clones never share a serial
+  into a per-VM OpenCore; the ROM is the guest MAC outside CNI
 - **CNI networking with TC redirect** — `--net cni` joins cocoon's forwarding
   plane so the guest DHCPs a real LAN IP; also `user`/`tap`/`bridge`
 - **Reachable VNC** — loopback VNC on user/tap/bridge; a host-side proxy fronts

docs/networking.md

@@ -11,8 +11,12 @@
 
 `tap`/`bridge`/`cni` make a macOS VM join the **same** forwarding plane as cocoon's Cloud
 Hypervisor / Firecracker VMs on the node, so the guest can DHCP a **real LAN IP** from the upstream
-network. The guest NIC MAC stays equal to the SMBIOS ROM. Auto-create (`bridge`/`cni`) is Linux-only
-(needs `CAP_NET_ADMIN`); `user` and a pre-created `--tap` work everywhere.
+network. In `tap` and `bridge` mode the guest NIC MAC stays equal to the SMBIOS ROM. Auto-create
+(`bridge`/`cni`) is Linux-only (needs `CAP_NET_ADMIN`); `user` and a pre-created `--tap` work
+everywhere.
+
+In `cni` mode, the guest NIC uses the MAC CNI assigned to `eth0` because `macspoofchk` allow-lists
+that address; the SMBIOS ROM identity remains unchanged.
 
 Auto-created devices carry cocoon-macos's own host name family (`net_scope` `cm`: TAPs
 `cm<vmid8>-<nic>`, netns `cm-<vmid>`), so a cocoon daemon's GC on the same node never reads a live

qemu/launch.go

@@ -36,7 +36,7 @@ type Spec struct {
 	OpenCore string
 	OVMFCode string
 	OVMFVars string
-	MAC      string // set to the SMBIOS ROM for --random-smbios
+	MAC      string // guest NIC MAC: SMBIOS ROM by default, CNI eth0 in CNI mode
 	Tap      string // pre-created host TAP; set => -netdev tap (bridged/routed), empty => user-mode SLIRP
 
 	MonSock string

qemu/smbios.go

@@ -17,7 +17,7 @@ type SMBIOS struct {
 	Serial string `json:"serial"` // SystemSerialNumber
 	MLB    string `json:"mlb"`    // board serial
 	UUID   string `json:"uuid"`   // SystemUUID
-	ROM    string `json:"rom"`    // 6-byte ROM as hex; also the guest en0 MAC
+	ROM    string `json:"rom"`    // 6-byte ROM as hex; default guest NIC MAC outside CNI
 }
 
 // RandomSMBIOS generates a unique per-VM identity (fixed model + random serial/MLB/UUID/ROM).
@@ -41,7 +41,7 @@ func RandomSMBIOS() (SMBIOS, error) {
 	return SMBIOS{Model: smbiosModel, Serial: serial, MLB: mlb, UUID: uuid, ROM: rom}, nil
 }
 
-// MAC returns the ROM formatted as the guest NIC MAC (so en0 == ROM, as iServices expects).
+// MAC returns the ROM formatted as the default guest NIC MAC; CNI supplies its own runtime MAC.
 func (s SMBIOS) MAC() string {
 	b, err := hex.DecodeString(s.ROM)
 	if err != nil || len(b) != 6 {