The bridging output function puts the mbuf directly on the interfaces send

queue so the output network card must support the same tagging mechanism as
how the frame was input (prepended Ethernet header tag or stripped HW mflag).

Now the vlan Ethernet header is _always_ stripped in ether_input and the mbuf
flagged, only only network cards with VLAN_HWTAGGING enabled would properly
re-tag any outgoing vlan frames.

If the outgoing interface does not support hardware tagging then readd the vlan
header to the front of the frame. Move the common vlan encapsulation in to
ether_vlanencap().

Reported by:	Erik Osterholm, Jon Otterholm
MFC after:	1 week

4 files changed, 47 insertions, 29 deletions

diff --git a/sys/net/ethernet.h b/sys/net/ethernet.h
index 29a5316..c5b6118 100644
--- a/sys/net/ethernet.h
+++ b/sys/net/ethernet.h
@@ -386,6 +386,7 @@ extern	int  ether_output_frame(struct ifnet *, struct mbuf *);
 extern	char *ether_sprintf(const u_int8_t *);
 void	ether_vlan_mtap(struct bpf_if *, struct mbuf *,
 	    void *, u_int);
+struct mbuf  *ether_vlanencap(struct mbuf *, int);
 
 #else /* _KERNEL */
 
diff --git a/sys/net/if_bridge.c b/sys/net/if_bridge.c
index e464d96..f29063d 100644
--- a/sys/net/if_bridge.c
+++ b/sys/net/if_bridge.c
@@ -1653,7 +1653,23 @@ bridge_enqueue(struct bridge_softc *sc, struct ifnet *dst_ifp, struct mbuf *m)
 	for (; m; m = m0) {
 		m0 = m->m_nextpkt;
 		m->m_nextpkt = NULL;
-		
+
+		/*
+		 * If underlying interface can not do VLAN tag insertion itself
+		 * then attach a packet tag that holds it.
+		 */
+		if ((m->m_flags & M_VLANTAG) &&
+		    (dst_ifp->if_capenable & IFCAP_VLAN_HWTAGGING) == 0) {
+			m = ether_vlanencap(m, m->m_pkthdr.ether_vtag);
+			if (m == NULL) {
+				if_printf(dst_ifp,
+				    "unable to prepend VLAN header\n");
+				dst_ifp->if_oerrors++;
+				continue;
+			}
+			m->m_flags &= ~M_VLANTAG;
+		}
+
 		if (err == 0)
 			IFQ_ENQUEUE(&dst_ifp->if_snd, m, err);
 	}
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 53e9b64..9509eb5 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1249,5 +1249,33 @@ ether_vlan_mtap(struct bpf_if *bp, struct mbuf *m, void *data, u_int dlen)
 	m->m_data -= sizeof(struct ether_header);
 }
 
+struct mbuf *
+ether_vlanencap(struct mbuf *m, int tag)
+{
+	struct ether_vlan_header *evl;
+
+	M_PREPEND(m, ETHER_VLAN_ENCAP_LEN, M_DONTWAIT);
+	if (m == NULL)
+		return (NULL);
+	/* M_PREPEND takes care of m_len, m_pkthdr.len for us */
+
+	if (m->m_len < sizeof(*evl)) {
+		m = m_pullup(m, sizeof(*evl));
+		if (m == NULL)
+			return (NULL);
+	}
+
+	/*
+	 * Transform the Ethernet header into an Ethernet header
+	 * with 802.1Q encapsulation.
+	 */
+	evl = mtod(m, struct ether_vlan_header *);
+	bcopy((char *)evl + ETHER_VLAN_ENCAP_LEN,
+	    (char *)evl, ETHER_HDR_LEN - ETHER_TYPE_LEN);
+	evl->evl_encap_proto = htons(ETHERTYPE_VLAN);
+	evl->evl_tag = htons(tag);
+	return (m);
+}
+
 DECLARE_MODULE(ether, ether_mod, SI_SUB_INIT_IF, SI_ORDER_ANY);
 MODULE_VERSION(ether, 1);
diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 8fb7a1f..6cce6e9 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -850,40 +850,13 @@ vlan_start(struct ifnet *ifp)
 			m->m_pkthdr.ether_vtag = ifv->ifv_tag;
 			m->m_flags |= M_VLANTAG;
 		} else {
-			struct ether_vlan_header *evl;
-
-			M_PREPEND(m, ifv->ifv_encaplen, M_DONTWAIT);
+			m = ether_vlanencap(m, ifv->ifv_tag);
 			if (m == NULL) {
 				if_printf(ifp,
 				    "unable to prepend VLAN header\n");
 				ifp->if_oerrors++;
 				continue;
 			}
-			/* M_PREPEND takes care of m_len, m_pkthdr.len for us */
-
-			if (m->m_len < sizeof(*evl)) {
-				m = m_pullup(m, sizeof(*evl));
-				if (m == NULL) {
-					if_printf(ifp,
-					    "cannot pullup VLAN header\n");
-					ifp->if_oerrors++;
-					continue;
-				}
-			}
-
-			/*
-			 * Transform the Ethernet header into an Ethernet header
-			 * with 802.1Q encapsulation.
-			 */
-			evl = mtod(m, struct ether_vlan_header *);
-			bcopy((char *)evl + ifv->ifv_encaplen,
-			      (char *)evl, ETHER_HDR_LEN - ETHER_TYPE_LEN);
-			evl->evl_encap_proto = htons(ifv->ifv_proto);
-			evl->evl_tag = htons(ifv->ifv_tag);
-#ifdef DEBUG
-			printf("%s: %*D\n", __func__, (int)sizeof(*evl),
-			    (unsigned char *)evl, ":");
-#endif
 		}
 
 		/*