netlink: add interface notification on link status / flags change.

* Add link-state change notifications by subscribing to ifnet_link_event.
 In the Linux netlink model, link state is reported in 2 places: first is
 the IFLA_OPERSTATE, which stores state per RFC2863.
 The second is an IFF_LOWER_UP interface flag. As many applications rely
 on the latter, reserve 1 bit from if_flags, named as IFF_NETLINK_1.
 This flag is mapped to IFF_LOWER_UP in the netlink headers. This is done
 to avoid making applications think this flag is actually
 supported / presented in non-netlink outputs.
* Add flag change notifications, by hooking into rt_ifmsg().
 In the netlink model, notification should include the bitmask for the
 change flags. Update rt_ifmsg() to include such bitmask.

Differential Revision: https://reviews.freebsd.org/D37597

(cherry picked from commit 1bcd230f9508b3c917f26be4b905e4b5141decea)

6 files changed, 39 insertions, 9 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index d42b642e8d18..7423c4963f57 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -2222,7 +2222,7 @@ if_unroute(struct ifnet *ifp, int flag, int fam)
 
 	if (ifp->if_carp)
 		(*carp_linkstate_p)(ifp);
-	rt_ifmsg(ifp);
+	rt_ifmsg_14(ifp, IFF_UP);
 }
 
 /*
@@ -2246,7 +2246,7 @@ if_route(struct ifnet *ifp, int flag, int fam)
 	NET_EPOCH_EXIT(et);
 	if (ifp->if_carp)
 		(*carp_linkstate_p)(ifp);
-	rt_ifmsg(ifp);
+	rt_ifmsg_14(ifp, IFF_UP);
 #ifdef INET6
 	in6_if_up(ifp);
 #endif
@@ -2290,7 +2290,7 @@ do_link_state_change(void *arg, int pending)
 	link_state = ifp->if_link_state;
 
 	CURVNET_SET(ifp->if_vnet);
-	rt_ifmsg(ifp);
+	rt_ifmsg_14(ifp, 0);
 	if (ifp->if_vlantrunk != NULL)
 		(*vlan_link_state_p)(ifp);
 
@@ -2760,7 +2760,7 @@ ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
 		error = (*ifp->if_ioctl)(ifp, cmd, data);
 		if (error == 0) {
 			getmicrotime(&ifp->if_lastchange);
-			rt_ifmsg(ifp);
+			rt_ifmsg_14(ifp, 0);
 #ifdef INET
 			DEBUGNET_NOTIFY_MTU(ifp);
 #endif
@@ -3190,7 +3190,7 @@ if_setflag(struct ifnet *ifp, int flag, int pflag, int *refcount, int onswitch)
 	if (error)
 		goto recover;
 	/* Notify userland that interface flags have changed */
-	rt_ifmsg(ifp);
+	rt_ifmsg_14(ifp, flag);
 	return (0);
 
 recover:
diff --git a/sys/net/if.h b/sys/net/if.h
index 782e792cf87c..409289869c27 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -163,6 +163,7 @@ struct if_data {
 #define	IFF_DYING	0x200000	/* (n) interface is winding down */
 #define	IFF_RENAMING	0x400000	/* (n) interface is being renamed */
 #define	IFF_NOGROUP	0x800000	/* (n) interface is not part of any groups */
+#define	IFF_NETLINK_1	0x1000000	/* (n) used by netlink */
 
 /*
  * Old names for driver flags so that user space tools can continue to use
diff --git a/sys/net/route.c b/sys/net/route.c
index b4076123e5d6..80d08d1bc7f0 100644
--- a/sys/net/route.c
+++ b/sys/net/route.c
@@ -813,12 +813,34 @@ rt_routemsg_info(int cmd, struct rt_addrinfo *info, int fibnum)
 	return (rtsock_routemsg_info(cmd, info, fibnum));
 }
 
+void
+rt_ifmsg(struct ifnet *ifp)
+{
+	rt_ifmsg_14(ifp, 0);
+}
+
+void
+rt_ifmsg_14(struct ifnet *ifp, int if_flags_mask)
+{
+	rtsock_callback_p->ifmsg_f(ifp, if_flags_mask);
+	netlink_callback_p->ifmsg_f(ifp, if_flags_mask);
+}
+
 /* Netlink-related callbacks needed to glue rtsock, netlink and linuxolator */
 static void
 ignore_route_event(uint32_t fibnum, const struct rib_cmd_info *rc)
 {
 }
-static struct rtbridge ignore_cb = { .route_f = ignore_route_event };
+
+static void
+ignore_ifmsg_event(struct ifnet *ifp, int if_flags_mask)
+{
+}
+
+static struct rtbridge ignore_cb = {
+	.route_f = ignore_route_event,
+	.ifmsg_f = ignore_ifmsg_event,
+};
 
 void *linux_netlink_p = NULL; /* Callback pointer for Linux translator functions */
 struct rtbridge *rtsock_callback_p = &ignore_cb;
diff --git a/sys/net/route.h b/sys/net/route.h
index a2394d54b92f..3dac437426b0 100644
--- a/sys/net/route.h
+++ b/sys/net/route.h
@@ -416,6 +416,7 @@ struct rib_head;
 
 void	 rt_ieee80211msg(struct ifnet *, int, void *, size_t);
 void	 rt_ifmsg(struct ifnet *);
+void	 rt_ifmsg_14(struct ifnet *, int);
 void	 rt_missmsg(int, struct rt_addrinfo *, int, int);
 void	 rt_missmsg_fib(int, struct rt_addrinfo *, int, int, int);
 int	 rt_addrmsg(int, struct ifaddr *, int);
diff --git a/sys/net/route/route_ctl.h b/sys/net/route/route_ctl.h
index d150da6264d4..e8560e681ddb 100644
--- a/sys/net/route/route_ctl.h
+++ b/sys/net/route/route_ctl.h
@@ -191,8 +191,10 @@ void rib_notify(struct rib_head *rnh, enum rib_subscription_type type,
 
 /* Event bridge */
 typedef void route_event_f(uint32_t fibnum, const struct rib_cmd_info *rc);
+typedef void ifmsg_event_f(struct ifnet *ifp, int if_flags_mask);
 struct rtbridge{
 	route_event_f	*route_f;
+	ifmsg_event_f	*ifmsg_f;
 };
 extern struct rtbridge *rtsock_callback_p;
 extern struct rtbridge *netlink_callback_p;
diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index 69a5698e4b5f..fc9439602c13 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -211,6 +211,7 @@ static void	send_rtm_reply(struct socket *so, struct rt_msghdr *rtm,
 static bool	can_export_rte(struct ucred *td_ucred, bool rt_is_host,
 			const struct sockaddr *rt_dst);
 static void	rtsock_notify_event(uint32_t fibnum, const struct rib_cmd_info *rc);
+static void	rtsock_ifmsg(struct ifnet *ifp, int if_flags_mask);
 
 static struct netisr_handler rtsock_nh = {
 	.nh_name = "rtsock",
@@ -288,7 +289,10 @@ rts_handle_route_event(uint32_t fibnum, const struct rib_cmd_info *rc)
 #endif
 		report_route_event(rc, (void *)(uintptr_t)fibnum);
 }
-static struct rtbridge rtsbridge = { .route_f = rts_handle_route_event };
+static struct rtbridge rtsbridge = {
+	.route_f = rts_handle_route_event,
+	.ifmsg_f = rtsock_ifmsg,
+};
 static struct rtbridge *rtsbridge_orig_p;
 
 static void
@@ -1984,8 +1988,8 @@ rt_missmsg(int type, struct rt_addrinfo *rtinfo, int flags, int error)
  * This routine is called to generate a message from the routing
  * socket indicating that the status of a network interface has changed.
  */
-void
-rt_ifmsg(struct ifnet *ifp)
+static void
+rtsock_ifmsg(struct ifnet *ifp, int if_flags_mask __unused)
 {
 	struct if_msghdr *ifm;
 	struct mbuf *m;