Propagate host-side tap(4) lladdr to guest vm process to allow unicast dhcp

and bootp renewals with vmd(8)'s built-in dhcp server. Previous behavior
ignored did not intercept these packets and instead transmitted them.

This should make vmd(8)'s dhcp behave more as a true dhcp server should and
allows it to work properly with the new dhcpleased(8) attempting a renewal.

OK mlarkin@

9 files changed, 124 insertions, 12 deletions

diff --git a/usr.sbin/vmd/config.c b/usr.sbin/vmd/config.c
index 9bcf49b5304..46acf78ce8a 100644
--- a/usr.sbin/vmd/config.c
+++ b/usr.sbin/vmd/config.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: config.c,v 1.60 2021/03/19 09:29:33 kn Exp $	*/
+/*	$OpenBSD: config.c,v 1.61 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Reyk Floeter <reyk@openbsd.org>
@@ -227,6 +227,7 @@ config_setvm(struct privsep *ps, struct vmd_vm *vm, uint32_t peerid, uid_t uid)
 	char			 base[PATH_MAX];
 	unsigned int		 unit;
 	struct timeval		 tv, rate, since_last;
+	struct vmop_addr_req	 var;
 
 	errno = 0;
 
@@ -499,6 +500,12 @@ config_setvm(struct privsep *ps, struct vmd_vm *vm, uint32_t peerid, uid_t uid)
 		proc_compose_imsg(ps, PROC_VMM, -1,
 		    IMSG_VMDOP_START_VM_IF, vm->vm_vmid, tapfds[i],
 		    &i, sizeof(i));
+
+		memset(&var, 0, sizeof(var));
+		var.var_vmid = vm->vm_vmid;
+		var.var_nic_idx = i;
+		proc_compose_imsg(ps, PROC_PRIV, -1, IMSG_VMDOP_PRIV_GET_ADDR,
+		    vm->vm_vmid, dup(tapfds[i]), &var, sizeof(var));
 	}
 
 	if (!(vm->vm_state & VM_STATE_RECEIVED))
diff --git a/usr.sbin/vmd/dhcp.c b/usr.sbin/vmd/dhcp.c
index 63d17d0dcc9..987d4386f9f 100644
--- a/usr.sbin/vmd/dhcp.c
+++ b/usr.sbin/vmd/dhcp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcp.c,v 1.8 2018/12/27 19:51:30 anton Exp $	*/
+/*	$OpenBSD: dhcp.c,v 1.9 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2017 Reyk Floeter <reyk@openbsd.org>
@@ -57,8 +57,11 @@ dhcp_request(struct vionet_dev *dev, char *buf, size_t buflen, char **obuf)
 	if ((offset = decode_hw_header(buf, buflen, 0, &pc, HTYPE_ETHER)) < 0)
 		return (-1);
 
-	if (memcmp(pc.pc_smac, dev->mac, ETHER_ADDR_LEN) != 0 ||
-	    memcmp(pc.pc_dmac, broadcast, ETHER_ADDR_LEN) != 0)
+	if (memcmp(pc.pc_dmac, broadcast, ETHER_ADDR_LEN) != 0 &&
+	    memcmp(pc.pc_dmac, dev->hostmac, ETHER_ADDR_LEN) != 0)
+		return (-1);
+
+	if (memcmp(pc.pc_smac, dev->mac, ETHER_ADDR_LEN) != 0)
 		return (-1);
 
 	if ((offset = decode_udp_ip_header(buf, buflen, offset, &pc)) < 0)
diff --git a/usr.sbin/vmd/priv.c b/usr.sbin/vmd/priv.c
index 7335f0c4a89..6718174765a 100644
--- a/usr.sbin/vmd/priv.c
+++ b/usr.sbin/vmd/priv.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: priv.c,v 1.16 2021/02/28 22:56:09 dlg Exp $	*/
+/*	$OpenBSD: priv.c,v 1.17 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2016 Reyk Floeter <reyk@openbsd.org>
@@ -92,6 +92,8 @@ priv_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 	struct ifaliasreq	 ifra;
 	struct in6_aliasreq	 in6_ifra;
 	struct if_afreq		 ifar;
+	struct vmop_addr_req	 vareq;
+	struct vmop_addr_result	 varesult;
 	char			 type[IF_NAMESIZE];
 
 	switch (imsg->hdr.type) {
@@ -115,6 +117,7 @@ priv_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 		break;
 	case IMSG_VMDOP_CONFIG:
 	case IMSG_CTL_RESET:
+	case IMSG_VMDOP_PRIV_GET_ADDR:
 		break;
 	default:
 		return (-1);
@@ -245,6 +248,22 @@ priv_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 		if (ioctl(env->vmd_fd6, SIOCAIFADDR_IN6, &in6_ifra) == -1)
 			log_warn("SIOCAIFADDR_IN6");
 		break;
+	case IMSG_VMDOP_PRIV_GET_ADDR:
+		IMSG_SIZE_CHECK(imsg, &vareq);
+		memcpy(&vareq, imsg->data, sizeof(vareq));
+
+		varesult.var_vmid = vareq.var_vmid;
+		varesult.var_nic_idx = vareq.var_nic_idx;
+
+		/* resolve lladdr for the tap(4) and send back to parent */
+		if (ioctl(imsg->fd, SIOCGIFADDR, &varesult.var_addr) != 0)
+			log_warn("SIOCGIFADDR");
+		else
+			proc_compose_imsg(ps, PROC_PARENT, -1,
+			    IMSG_VMDOP_PRIV_GET_ADDR_RESPONSE, imsg->hdr.peerid,
+			    -1, &varesult, sizeof(varesult));
+		close(imsg->fd);
+		break;
 	case IMSG_VMDOP_CONFIG:
 		config_getconfig(env, imsg);
 		break;
diff --git a/usr.sbin/vmd/virtio.c b/usr.sbin/vmd/virtio.c
index 1d269ed65ff..f937bf602f6 100644
--- a/usr.sbin/vmd/virtio.c
+++ b/usr.sbin/vmd/virtio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: virtio.c,v 1.83 2021/03/26 17:40:03 deraadt Exp $	*/
+/*	$OpenBSD: virtio.c,v 1.84 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -2034,6 +2034,31 @@ virtio_init(struct vmd_vm *vm, int child_cdrom,
 	evtimer_set(&vmmci.timeout, vmmci_timeout, NULL);
 }
 
+/*
+ * vionet_set_hostmac
+ *
+ * Sets the hardware address for the host-side tap(4) on a vionet_dev.
+ *
+ * This should only be called from the event-loop thread
+ *
+ * vm: pointer to the current vmd_vm instance
+ * idx: index into the array of vionet_dev's for the target vionet_dev
+ * addr: ethernet address to set
+ */
+void
+vionet_set_hostmac(struct vmd_vm *vm, unsigned int idx, uint8_t *addr)
+{
+	struct vmop_create_params *vmc = &vm->vm_params;
+	struct vm_create_params	  *vcp = &vmc->vmc_params;
+	struct vionet_dev	  *dev;
+
+	if (idx > vcp->vcp_nnics)
+		fatalx("vionet_set_hostmac");
+
+	dev = &vionet[idx];
+	memcpy(dev->hostmac, addr, sizeof(dev->hostmac));
+}
+
 void
 virtio_shutdown(struct vmd_vm *vm)
 {
diff --git a/usr.sbin/vmd/virtio.h b/usr.sbin/vmd/virtio.h
index 1672cca267c..9d7ef81831d 100644
--- a/usr.sbin/vmd/virtio.h
+++ b/usr.sbin/vmd/virtio.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: virtio.h,v 1.36 2021/01/07 17:11:38 tracey Exp $	*/
+/*	$OpenBSD: virtio.h,v 1.37 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -208,6 +208,7 @@ struct vionet_dev {
 	uint32_t vm_vmid;
 	int irq;
 	uint8_t mac[6];
+	uint8_t hostmac[6];
 
 	int idx;
 	int lockedmac;
@@ -298,6 +299,7 @@ void vionet_notify_rx(struct vionet_dev *);
 int vionet_notify_tx(struct vionet_dev *);
 void vionet_process_rx(uint32_t);
 int vionet_enq_rx(struct vionet_dev *, char *, ssize_t, int *);
+void vionet_set_hostmac(struct vmd_vm *, unsigned int, uint8_t *);
 
 int vmmci_io(int, uint16_t, uint32_t *, uint8_t *, void *, uint8_t);
 int vmmci_dump(int);
diff --git a/usr.sbin/vmd/vm.c b/usr.sbin/vmd/vm.c
index bf515eb3778..9ffd1598b21 100644
--- a/usr.sbin/vmd/vm.c
+++ b/usr.sbin/vmd/vm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm.c,v 1.60 2021/03/19 09:29:33 kn Exp $	*/
+/*	$OpenBSD: vm.c,v 1.61 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -394,6 +394,7 @@ vm_dispatch_vmm(int fd, short event, void *arg)
 {
 	struct vmd_vm		*vm = arg;
 	struct vmop_result	 vmr;
+	struct vmop_addr_result	 var;
 	struct imsgev		*iev = &vm->vm_iev;
 	struct imsgbuf		*ibuf = &iev->ibuf;
 	struct imsg		 imsg;
@@ -471,6 +472,16 @@ vm_dispatch_vmm(int fd, short event, void *arg)
 				_exit(0);
 			}
 			break;
+		case IMSG_VMDOP_PRIV_GET_ADDR_RESPONSE:
+			IMSG_SIZE_CHECK(&imsg, &var);
+			memcpy(&var, imsg.data, sizeof(var));
+
+			log_debug("%s: received tap addr %s for nic %d",
+			    vm->vm_params.vmc_params.vcp_name,
+			    ether_ntoa((void *)var.var_addr), var.var_nic_idx);
+
+			vionet_set_hostmac(vm, var.var_nic_idx, var.var_addr);
+			break;
 		default:
 			fatalx("%s: got invalid imsg %d from %s",
 			    __func__, imsg.hdr.type,
diff --git a/usr.sbin/vmd/vmd.c b/usr.sbin/vmd/vmd.c
index 3bceb5c0593..cd585d5a197 100644
--- a/usr.sbin/vmd/vmd.c
+++ b/usr.sbin/vmd/vmd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmd.c,v 1.120 2021/01/27 07:21:54 deraadt Exp $	*/
+/*	$OpenBSD: vmd.c,v 1.121 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Reyk Floeter <reyk@openbsd.org>
@@ -58,6 +58,7 @@ void	 vmd_shutdown(void);
 int	 vmd_control_run(void);
 int	 vmd_dispatch_control(int, struct privsep_proc *, struct imsg *);
 int	 vmd_dispatch_vmm(int, struct privsep_proc *, struct imsg *);
+int	 vmd_dispatch_priv(int, struct privsep_proc *, struct imsg *);
 int	 vmd_check_vmh(struct vm_dump_header *);
 
 int	 vm_instance(struct privsep *, struct vmd_vm **,
@@ -70,7 +71,7 @@ struct vmd	*env;
 
 static struct privsep_proc procs[] = {
 	/* Keep "priv" on top as procs[0] */
-	{ "priv",	PROC_PRIV,	NULL, priv },
+	{ "priv",	PROC_PRIV,	vmd_dispatch_priv, priv },
 	{ "control",	PROC_CONTROL,	vmd_dispatch_control, control },
 	{ "vmm",	PROC_VMM,	vmd_dispatch_vmm, vmm, vmm_shutdown },
 };
@@ -551,6 +552,24 @@ vmd_dispatch_vmm(int fd, struct privsep_proc *p, struct imsg *imsg)
 }
 
 int
+vmd_dispatch_priv(int fd, struct privsep_proc *p, struct imsg *imsg)
+{
+	struct vmop_addr_result	 var;
+
+	switch (imsg->hdr.type) {
+	case IMSG_VMDOP_PRIV_GET_ADDR_RESPONSE:
+		IMSG_SIZE_CHECK(imsg, &var);
+		memcpy(&var, imsg->data, sizeof(var));
+		proc_forward_imsg(p->p_ps, imsg, PROC_VMM, -1);
+		break;
+	default:
+		return (-1);
+	}
+
+	return (0);
+}
+
+int
 vmd_check_vmh(struct vm_dump_header *vmh)
 {
 	int i;
diff --git a/usr.sbin/vmd/vmd.h b/usr.sbin/vmd/vmd.h
index a2d80eb2181..a9d752a2c2a 100644
--- a/usr.sbin/vmd/vmd.h
+++ b/usr.sbin/vmd/vmd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmd.h,v 1.102 2021/03/19 09:29:33 kn Exp $	*/
+/*	$OpenBSD: vmd.h,v 1.103 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -120,6 +120,8 @@ enum imsg_type {
 	IMSG_VMDOP_PRIV_IFADDR,
 	IMSG_VMDOP_PRIV_IFADDR6,
 	IMSG_VMDOP_PRIV_IFRDOMAIN,
+	IMSG_VMDOP_PRIV_GET_ADDR,
+	IMSG_VMDOP_PRIV_GET_ADDR_RESPONSE,
 	IMSG_VMDOP_VM_SHUTDOWN,
 	IMSG_VMDOP_VM_REBOOT,
 	IMSG_VMDOP_CONFIG,
@@ -158,6 +160,17 @@ struct vmop_ifreq {
 	struct sockaddr_storage		 vfr_mask;
 };
 
+struct vmop_addr_req {
+	uint32_t		 var_vmid;
+	unsigned int		 var_nic_idx;
+};
+
+struct vmop_addr_result {
+	uint32_t		 var_vmid;
+	unsigned int		 var_nic_idx;
+	uint8_t			 var_addr[ETHER_ADDR_LEN];
+};
+
 struct vmop_owner {
 	uid_t			 uid;
 	int64_t			 gid;
diff --git a/usr.sbin/vmd/vmm.c b/usr.sbin/vmd/vmm.c
index 19964a86f80..faebf670dee 100644
--- a/usr.sbin/vmd/vmm.c
+++ b/usr.sbin/vmd/vmm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmm.c,v 1.97 2021/03/02 02:56:22 jsg Exp $	*/
+/*	$OpenBSD: vmm.c,v 1.98 2021/03/29 23:37:01 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -109,6 +109,7 @@ vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 	struct vmop_id		 vid;
 	struct vmop_result	 vmr;
 	struct vmop_create_params vmc;
+	struct vmop_addr_result  var;
 	uint32_t		 id = 0, peerid = imsg->hdr.peerid;
 	pid_t			 pid = 0;
 	unsigned int		 mode, flags;
@@ -332,6 +333,18 @@ vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 			res = ENOENT;
 		cmd = IMSG_VMDOP_START_VM_RESPONSE;
 		break;
+	case IMSG_VMDOP_PRIV_GET_ADDR_RESPONSE:
+		IMSG_SIZE_CHECK(imsg, &var);
+		memcpy(&var, imsg->data, sizeof(var));
+		if ((vm = vm_getbyvmid(var.var_vmid)) == NULL) {
+			res = ENOENT;
+			break;
+		}
+		/* Forward hardware address details to the guest vm */
+		imsg_compose_event(&vm->vm_iev,
+		    imsg->hdr.type, imsg->hdr.peerid, imsg->hdr.pid,
+		    imsg->fd, &var, sizeof(var));
+		break;
 	default:
 		return (-1);
 	}