From 2748f5e225ff2609bc6086a165874a65b38b1a20 Mon Sep 17 00:00:00 2001
From: dv <dv@openbsd.org>
Date: Sat, 14 Jan 2023 20:55:55 +0000
Subject: [PATCH] Only open /dev/vmm once in vmd(8).

Have the parent process open /dev/vmm and send the fd to the vmm
child process. Only the vmm process and its resulting children
(guest vms) need it for ioctl calls.

ok kn@
---
 usr.sbin/vmd/vmd.c | 10 +++++++---
 usr.sbin/vmd/vmd.h |  3 ++-
 usr.sbin/vmd/vmm.c | 13 +++++++++----
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/usr.sbin/vmd/vmd.c b/usr.sbin/vmd/vmd.c
index 6bffb2519a3..0557a3101c9 100644
--- a/usr.sbin/vmd/vmd.c
+++ b/usr.sbin/vmd/vmd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmd.c,v 1.135 2022/12/28 21:30:19 jmc Exp $	*/
+/*	$OpenBSD: vmd.c,v 1.136 2023/01/14 20:55:55 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Reyk Floeter <reyk@openbsd.org>
@@ -847,8 +847,8 @@ main(int argc, char **argv)
 	proc_priv->p_pw = &proc_privpw; /* initialized to all 0 */
 	proc_priv->p_chroot = ps->ps_pw->pw_dir; /* from VMD_USER */
 
-	/* Open /dev/vmm */
-	if (env->vmd_noaction == 0) {
+	/* Open /dev/vmm early. */
+	if (env->vmd_noaction == 0 && proc_id == PROC_PARENT) {
 		env->vmd_fd = open(VMM_NODE, O_RDWR);
 		if (env->vmd_fd == -1)
 			fatal("%s", VMM_NODE);
@@ -971,6 +971,10 @@ vmd_configure(void)
 		exit(0);
 	}
 
+	/* Send VMM device fd to vmm proc. */
+	proc_compose_imsg(&env->vmd_ps, PROC_VMM, -1,
+	    IMSG_VMDOP_RECEIVE_VMM_FD, -1, env->vmd_fd, NULL, 0);
+
 	/* Send shared global configuration to all children */
 	if (config_setconfig(env) == -1)
 		return (-1);
diff --git a/usr.sbin/vmd/vmd.h b/usr.sbin/vmd/vmd.h
index f1ccfea1242..3e7f1d15970 100644
--- a/usr.sbin/vmd/vmd.h
+++ b/usr.sbin/vmd/vmd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmd.h,v 1.112 2022/12/23 19:25:22 dv Exp $	*/
+/*	$OpenBSD: vmd.h,v 1.113 2023/01/14 20:55:55 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -108,6 +108,7 @@ enum imsg_type {
 	IMSG_VMDOP_GET_INFO_VM_DATA,
 	IMSG_VMDOP_GET_INFO_VM_END_DATA,
 	IMSG_VMDOP_LOAD,
+	IMSG_VMDOP_RECEIVE_VMM_FD,
 	IMSG_VMDOP_RELOAD,
 	IMSG_VMDOP_PRIV_IFDESCR,
 	IMSG_VMDOP_PRIV_IFADD,
diff --git a/usr.sbin/vmd/vmm.c b/usr.sbin/vmd/vmm.c
index 6c2bdbd12a3..d9eff3c8f70 100644
--- a/usr.sbin/vmd/vmm.c
+++ b/usr.sbin/vmd/vmm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vmm.c,v 1.106 2022/11/06 11:54:08 dv Exp $	*/
+/*	$OpenBSD: vmm.c,v 1.107 2023/01/14 20:55:55 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -94,9 +94,6 @@ vmm_run(struct privsep *ps, struct privsep_proc *p, void *arg)
 	 */
 	if (pledge("stdio vmm sendfd recvfd proc", NULL) == -1)
 		fatal("pledge");
-
-	/* Get and terminate all running VMs */
-	get_info_vm(ps, NULL, 1);
 }
 
 int
@@ -315,6 +312,14 @@ vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 		    imsg->hdr.type, imsg->hdr.peerid, imsg->hdr.pid,
 		    imsg->fd, &var, sizeof(var));
 		break;
+	case IMSG_VMDOP_RECEIVE_VMM_FD:
+		if (env->vmd_fd > -1)
+			fatalx("already received vmm fd");
+		env->vmd_fd = imsg->fd;
+
+		/* Get and terminate all running VMs */
+		get_info_vm(ps, NULL, 1);
+		break;
 	default:
 		return (-1);
 	}
-- 
2.20.1