provide a tun_input() interface input handler for tun(4) packets.

this makes tun(4) more like tap(4). it now relies on the network
stack to set the rcvif, rdomain, count the packets, and lock
appropriately. right now it also means we consistently use if input
queues for both tun and tap, and return backpressure at the same
points.

the tun_input handler is then responsible for pulling the "link"
header off the packet and shoving it it into the various protocol
handlers as appropriate.

a consequence of having the stack count the bytes before tun_input
strips the header is ibytes now includes the 4 byte AF header.
however, this makes tun input consistent with the accounting on tun
output, which included those 4 bytes anyway.

1 files changed, 23 insertions, 29 deletions

diff --git a/sys/net/if_tun.c b/sys/net/if_tun.c
index 2b2c317a927..9ea301df771 100644
--- a/sys/net/if_tun.c
+++ b/sys/net/if_tun.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_tun.c,v 1.207 2020/01/24 01:17:22 dlg Exp $	*/
+/*	$OpenBSD: if_tun.c,v 1.208 2020/01/24 01:36:22 dlg Exp $	*/
 /*	$NetBSD: if_tun.c,v 1.24 1996/05/07 02:40:48 thorpej Exp $	*/
 
 /*
@@ -109,6 +109,7 @@ int	tun_dev_poll(struct tun_softc *, int, struct proc *);
 int	tun_dev_kqfilter(struct tun_softc *, struct knote *);
 
 int	tun_ioctl(struct ifnet *, u_long, caddr_t);
+int	tun_input(struct ifnet *, struct mbuf *, void *);
 int	tun_output(struct ifnet *, struct mbuf *, struct sockaddr *,
 	    struct rtentry *);
 int	tun_enqueue(struct ifnet *, struct mbuf *);
@@ -240,9 +241,12 @@ tun_create(struct if_clone *ifc, int unit, int flags)
 
 		if_attach(ifp);
 		if_alloc_sadl(ifp);
+
 #if NBPFILTER > 0
 		bpfattach(&ifp->if_bpf, ifp, DLT_LOOP, sizeof(u_int32_t));
 #endif
+
+		if_ih_insert(ifp, tun_input, NULL);
 	} else {
 		if (tun_list_insert(&tap_softc_list, sc) != 0)
 			goto exists;
@@ -275,7 +279,9 @@ tun_clone_destroy(struct ifnet *ifp)
 	klist_invalidate(&sc->sc_wsel.si_note);
 	splx(s);
 
-	if (sc->sc_flags & TUN_LAYER2)
+	if (!ISSET(sc->sc_flags, TUN_LAYER2))
+		if_ih_remove(ifp, tun_input, NULL);
+	else
 		ether_ifdetach(ifp);
 
 	if_detach(ifp);
@@ -814,10 +820,10 @@ int
 tun_dev_write(struct tun_softc *sc, struct uio *uio, int ioflag, int align)
 {
 	struct ifnet		*ifp;
-	uint32_t		af;
 	struct mbuf		*m0;
 	int			error = 0;
 	size_t			mlen;
+	struct mbuf_list	ml = MBUF_LIST_INITIALIZER();
 
 	ifp = &sc->sc_if;
 	TUNDEBUG(("%s: tunwrite\n", ifp->if_xname));
@@ -850,31 +856,26 @@ tun_dev_write(struct tun_softc *sc, struct uio *uio, int ioflag, int align)
 	if (error != 0)
 		goto drop;
 
-	if (sc->sc_flags & TUN_LAYER2) {
-		struct mbuf_list ml = MBUF_LIST_INITIALIZER();
+	ml_enqueue(&ml, m0);
+	if_input(ifp, &ml);
+	return (0);
 
-		ml_enqueue(&ml, m0);
-		if_input(ifp, &ml);
-		return (0);
-	}
+drop:
+	m_freem(m0);
+	return (error);
+}
 
-#if NBPFILTER > 0
-	if (ifp->if_bpf)
-		bpf_mtap(ifp->if_bpf, m0, BPF_DIRECTION_IN);
-#endif
+int
+tun_input(struct ifnet *ifp, struct mbuf *m0, void *cookie)
+{
+	uint32_t		af;
+
+	KASSERT(m0->m_len >= sizeof(af));
 
 	af = *mtod(m0, uint32_t *);
 	/* strip the tunnel header */
 	m_adj(m0, sizeof(af));
 
-	m0->m_pkthdr.ph_rtableid = ifp->if_rdomain;
-	m0->m_pkthdr.ph_ifidx = ifp->if_index;
-
-	ifp->if_ipackets++;
-	ifp->if_ibytes += m0->m_pkthdr.len;
-
-	NET_LOCK();
-
 	switch (ntohl(af)) {
 	case AF_INET:
 		ipv4_input(ifp, m0);
@@ -891,17 +892,10 @@ tun_dev_write(struct tun_softc *sc, struct uio *uio, int ioflag, int align)
 #endif
 	default:
 		m_freem(m0);
-		error = EAFNOSUPPORT;
 		break;
 	}
 
-	NET_UNLOCK();
-
-	return (error);
-
-drop:
-	m_freem(m0);
-	return (error);
+	return (1);
 }
 
 /*