o eliminate widespread on-stack mbuf use for bpf by introducing

  a new bpf_mtap2 routine that does the right thing for an mbuf
  and a variable-length chunk of data that should be prepended.
o while we're sweeping the drivers, use u_int32_t uniformly when
  when prepending the address family (several places were assuming
  sizeof(int) was 4)
o return M_ASSERTVALID to BPF_MTAP* now that all stack-allocated
  mbufs have been eliminated; this may better be moved to the bpf
  routines

Reviewed by:	arch@ and several others

1 files changed, 53 insertions, 0 deletions

diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index c282dcf..c06312e 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -1227,6 +1227,50 @@ bpf_mtap(bp, m)
 }
 
 /*
+ * Incoming linkage from device drivers, when packet is in
+ * an mbuf chain and to be prepended by a contiguous header.
+ */
+void
+bpf_mtap2(bp, data, dlen, m)
+	struct bpf_if *bp;
+	void *data;
+	u_int dlen;
+	struct mbuf *m;
+{
+	struct mbuf mb;
+	struct bpf_d *d;
+	u_int pktlen, slen;
+
+	pktlen = m_length(m, NULL);
+	/*
+	 * Craft on-stack mbuf suitable for passing to bpf_filter.
+	 * Note that we cut corners here; we only setup what's
+	 * absolutely needed--this mbuf should never go anywhere else.
+	 */
+	mb.m_next = m;
+	mb.m_data = data;
+	mb.m_len = dlen;
+	pktlen += dlen;
+
+	BPFIF_LOCK(bp);
+	for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
+		if (!d->bd_seesent && (m->m_pkthdr.rcvif == NULL))
+			continue;
+		BPFD_LOCK(d);
+		++d->bd_rcount;
+		slen = bpf_filter(d->bd_filter, (u_char *)&mb, pktlen, 0);
+		if (slen != 0)
+#ifdef MAC
+			if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
+#endif
+				catchpacket(d, (u_char *)&mb, pktlen, slen,
+				    bpf_mcopy);
+		BPFD_UNLOCK(d);
+	}
+	BPFIF_UNLOCK(bp);
+}
+
+/*
  * Move the packet data from interface memory (pkt) into the
  * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
  * otherwise 0.  "copy" is the routine called to do the actual data
@@ -1580,6 +1624,15 @@ bpf_mtap(bp, m)
 }
 
 void
+bpf_mtap2(bp, d, l, m)
+	struct bpf_if *bp;
+	const void *d;
+	u_int l;
+	struct mbuf *m;
+{
+}
+
+void
 bpfattach(ifp, dlt, hdrlen)
 	struct ifnet *ifp;
 	u_int dlt, hdrlen;