diff --git a/sys/kern/kern_mbuf.c b/sys/kern/kern_mbuf.c
--- a/sys/kern/kern_mbuf.c
+++ b/sys/kern/kern_mbuf.c
@@ -1586,9 +1586,7 @@
     struct m_snd_tag **mstp)
 {
 
-	if (ifp->if_snd_tag_alloc == NULL)
-		return (EOPNOTSUPP);
-	return (ifp->if_snd_tag_alloc(ifp, params, mstp));
+	return (if_snd_tag_alloc(ifp, params, mstp));
 }
 
 void
@@ -1620,13 +1618,13 @@
 	u_short idx, gen;
 
 	M_ASSERTPKTHDR(m);
-	idx = m->m_pkthdr.rcvif->if_index;
-	gen = m->m_pkthdr.rcvif->if_idxgen;
+	idx = if_getindex(m->m_pkthdr.rcvif);
+	gen = if_getidxgen(m->m_pkthdr.rcvif);
 	m->m_pkthdr.rcvidx = idx;
 	m->m_pkthdr.rcvgen = gen;
 	if (__predict_false(m->m_pkthdr.leaf_rcvif != NULL)) {
-		idx = m->m_pkthdr.leaf_rcvif->if_index;
-		gen = m->m_pkthdr.leaf_rcvif->if_idxgen;
+		idx = if_getindex(m->m_pkthdr.leaf_rcvif);
+		gen = if_getidxgen(m->m_pkthdr.leaf_rcvif);
 	} else {
 		idx = -1;
 		gen = 0;
diff --git a/sys/net/if.c b/sys/net/if.c
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -4295,6 +4295,12 @@
 	return ((struct ifnet *)ifp)->if_index;
 }
 
+int
+if_getidxgen(const if_t ifp)
+{
+	return (ifp->if_idxgen);
+}
+
 void
 if_setdescr(if_t ifp, char *descrbuf)
 {
@@ -4845,6 +4851,16 @@
 	((struct ifnet *)ifp)->if_snd_tag_alloc = alloc_fn;
 }
 
+int
+if_snd_tag_alloc(struct ifnet *ifp, union if_snd_tag_alloc_params *params,
+    struct m_snd_tag **mstp)
+{
+
+	if (ifp->if_snd_tag_alloc == NULL)
+		return (EOPNOTSUPP);
+	return (ifp->if_snd_tag_alloc(ifp, params, mstp));
+}
+
 void
 if_setgetcounterfn(if_t ifp, if_get_counter_t fn)
 {
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -578,6 +578,7 @@
 int if_getcapenable(const if_t ifp);
 int if_getdunit(const if_t ifp);
 int if_getindex(const if_t ifp);
+int if_getidxgen(const if_t ifp);
 const char *if_getdname(const if_t ifp);
 void if_setdname(if_t ifp, const char *name);
 const char *if_name(if_t ifp);
@@ -650,6 +651,8 @@
 
 void *if_getafdata(if_t ifp, int);
 
+int if_snd_tag_alloc(struct ifnet *ifp, union if_snd_tag_alloc_params *params,
+    struct m_snd_tag **mstp);
 /*
  * Traversing through interface address lists.
  */