From 56be282bc999cc05dcd1ccb163b108d54f3ff448 Mon Sep 17 00:00:00 2001
From: "Bjoern A. Zeeb" <bz@FreeBSD.org>
Date: Wed, 28 Jul 2021 22:53:25 +0000
Subject: [PATCH] bhyve: net_backends, automatically IFF_UP tap devices

If you want communications with the outside world and tell bhyve to
create an interfaces then it should be usable as well.
Rather than relying on the sysctl net.link.tap.up_on_open automatically
try to IFF_UP the opened tap device.

MFC after:	10 days
Reviewed by:	markj, grehan
Differential Revision: https://reviews.freebsd.org/D31342
---
 usr.sbin/bhyve/net_backends.c | 51 +++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/usr.sbin/bhyve/net_backends.c b/usr.sbin/bhyve/net_backends.c
index 30c26aea458..cb1730fc77d 100644
--- a/usr.sbin/bhyve/net_backends.c
+++ b/usr.sbin/bhyve/net_backends.c
@@ -46,6 +46,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/uio.h>
 
 #include <net/if.h>
+#if defined(INET6) || defined(INET)
+#include <net/if_tap.h>
+#endif
 #include <net/netmap.h>
 #include <net/netmap_virt.h>
 #define NETMAP_WITH_LIBS
@@ -179,6 +182,17 @@ SET_DECLARE(net_backend_set, struct net_backend);
  * The tap backend
  */
 
+#if defined(INET6) || defined(INET)
+const int pf_list[] = {
+#if defined(INET6)
+	PF_INET6,
+#endif
+#if defined(INET)
+	PF_INET,
+#endif
+};
+#endif
+
 struct tap_priv {
 	struct mevent *mevp;
 	/*
@@ -211,6 +225,10 @@ tap_init(struct net_backend *be, const char *devname,
 	struct tap_priv *priv = (struct tap_priv *)be->opaque;
 	char tbuf[80];
 	int opt = 1;
+#if defined(INET6) || defined(INET)
+	struct ifreq ifrq;
+	int i, s;
+#endif
 #ifndef WITHOUT_CAPSICUM
 	cap_rights_t rights;
 #endif
@@ -238,6 +256,39 @@ tap_init(struct net_backend *be, const char *devname,
 		goto error;
 	}
 
+#if defined(INET6) || defined(INET)
+	/*
+	 * Try to UP the interface rather than relying on
+	 * net.link.tap.up_on_open.
+	  */
+	bzero(&ifrq, sizeof(ifrq));
+	if (ioctl(be->fd, TAPGIFNAME, &ifrq) < 0) {
+		WPRINTF(("Could not get interface name"));
+		goto error;
+	}
+
+	s = -1;
+	for (i = 0; s == -1 && i < nitems(pf_list); i++)
+		s = socket(pf_list[i], SOCK_DGRAM, 0);
+	if (s == -1) {
+		WPRINTF(("Could open socket"));
+		goto error;
+	}
+
+	if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
+		(void)close(s);
+		WPRINTF(("Could not get interface flags"));
+		goto error;
+	}
+	ifrq.ifr_flags |= IFF_UP;
+	if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
+		(void)close(s);
+		WPRINTF(("Could not set interface flags"));
+		goto error;
+	}
+	(void)close(s);
+#endif
+
 #ifndef WITHOUT_CAPSICUM
 	cap_rights_init(&rights, CAP_EVENT, CAP_READ, CAP_WRITE);
 	if (caph_rights_limit(be->fd, &rights) == -1)