Introduce bpf_mtap_af and bpf_mtap_hdr to be used when passing a mbuf chain

to bpf with either an address family or other header added.

These helpers only allocate a much smaller struct m_hdr on the stack when
needed, rather than leaving 256 byte struct mbufs on the stack in deep
call paths.  Also removes a fair bit of duplicated code.

commit now, tune after deraadt@

9 files changed, 72 insertions, 114 deletions

diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index 980066a9490..f329bde00b6 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.c,v 1.58 2005/04/20 19:52:42 reyk Exp $	*/
+/*	$OpenBSD: bpf.c,v 1.59 2005/07/31 03:52:18 pascoe Exp $	*/
 /*	$NetBSD: bpf.c,v 1.33 1997/02/21 23:59:35 thorpej Exp $	*/
 
 /*
@@ -1189,6 +1189,50 @@ bpf_mtap(caddr_t arg, struct mbuf *m)
 }
 
 /*
+ * Incoming linkage from device drivers, where we have a mbuf chain
+ * but need to prepend some arbitrary header from a linear buffer.
+ *
+ * Con up a minimal dummy header to pacify bpf.  Allocate (only) a
+ * struct m_hdr on the stack.  This is safe as bpf only reads from the
+ * fields in this header that we initialize, and will not try to free
+ * it or keep a pointer to it.
+ */
+int
+bpf_mtap_hdr(caddr_t arg, caddr_t data, u_int dlen, struct mbuf *m)
+{
+	struct m_hdr mh;
+
+	mh.mh_flags = 0;
+	mh.mh_next = m;
+	mh.mh_len = dlen;
+	mh.mh_data = data;
+
+	return bpf_mtap(arg, (struct mbuf *) &mh);
+}
+
+/*
+ * Incoming linkage from device drivers, where we have a mbuf chain
+ * but need to prepend the address family.
+ *
+ * Con up a minimal dummy header to pacify bpf.  We allocate (only) a
+ * struct m_hdr on the stack.  This is safe as bpf only reads from the
+ * fields in this header that we initialize, and will not try to free
+ * it or keep a pointer to it.
+ */
+int
+bpf_mtap_af(caddr_t arg, u_int32_t af, struct mbuf *m)
+{
+	struct m_hdr mh;
+
+	mh.mh_flags = 0;
+	mh.mh_next = m;
+	mh.mh_len = 4;
+	mh.mh_data = (caddr_t)⁡
+
+	return bpf_mtap(arg, (struct mbuf *) &mh);
+}
+
+/*
  * 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
diff --git a/sys/net/bpf.h b/sys/net/bpf.h
index c8465ea15c7..b6e8c0e1610 100644
--- a/sys/net/bpf.h
+++ b/sys/net/bpf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.h,v 1.30 2005/01/07 16:28:38 reyk Exp $	*/
+/*	$OpenBSD: bpf.h,v 1.31 2005/07/31 03:52:18 pascoe Exp $	*/
 /*	$NetBSD: bpf.h,v 1.15 1996/12/13 07:57:33 mikel Exp $	*/
 
 /*
@@ -262,6 +262,8 @@ struct bpf_dltlist {
 int	 bpf_validate(struct bpf_insn *, int);
 int	 bpf_tap(caddr_t, u_char *, u_int);
 int	 bpf_mtap(caddr_t, struct mbuf *);
+int	 bpf_mtap_hdr(caddr_t, caddr_t, u_int, struct mbuf *);
+int	 bpf_mtap_af(caddr_t, u_int32_t, struct mbuf *);
 void	 bpfattach(caddr_t *, struct ifnet *, u_int, u_int);
 void	 bpfdetach(struct ifnet *);
 void	 bpfilterattach(int);
diff --git a/sys/net/if_faith.c b/sys/net/if_faith.c
index b936b6f4204..e7a224c80ee 100644
--- a/sys/net/if_faith.c
+++ b/sys/net/if_faith.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_faith.c,v 1.17 2003/12/16 20:33:25 markus Exp $	*/
+/*	$OpenBSD: if_faith.c,v 1.18 2005/07/31 03:52:18 pascoe Exp $	*/
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
@@ -151,24 +151,8 @@ faithoutput(ifp, m, dst, rt)
 		m->m_data += sizeof(int);
 	}
 
-	if (ifp->if_bpf) {
-		/*
-		 * We need to prepend the address family as
-		 * a four byte field.  Cons up a faith header
-		 * to pacify bpf.  This is safe because bpf
-		 * will only read from the mbuf (i.e., it won't
-		 * try to free it or keep a pointer a to it).
-		 */
-		struct mbuf m0;
-		u_int32_t af = dst->sa_family;
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = 4;
-		m0.m_data = (char *)⁡
-
-		bpf_mtap(ifp->if_bpf, &m0);
-	}
+	if (ifp->if_bpf)
+		bpf_mtap_af(ifp->if_bpf, dst->sa_family);
 #endif
 
 	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
diff --git a/sys/net/if_gif.c b/sys/net/if_gif.c
index cce663f9a5f..931791e25a5 100644
--- a/sys/net/if_gif.c
+++ b/sys/net/if_gif.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_gif.c,v 1.31 2003/12/16 20:33:25 markus Exp $	*/
+/*	$OpenBSD: if_gif.c,v 1.32 2005/07/31 03:52:18 pascoe Exp $	*/
 /*	$KAME: if_gif.c,v 1.43 2001/02/20 08:51:07 itojun Exp $	*/
 
 /*
@@ -232,24 +232,8 @@ gif_output(ifp, m, dst, rt)
 	m->m_flags &= ~(M_BCAST|M_MCAST);
 
 #if NBPFILTER > 0
-	if (ifp->if_bpf) {
-		/*
-		 * We need to prepend the address family as
-		 * a four byte field.  Cons up a dummy header
-		 * to pacify bpf.  This is safe because bpf
-		 * will only read from the mbuf (i.e., it won't
-		 * try to free it or keep a pointer a to it).
-		 */
-		struct mbuf m0;
-		u_int32_t af = dst->sa_family;
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = 4;
-		m0.m_data = (char *)⁡
-		
-		bpf_mtap(ifp->if_bpf, &m0);
-	}
+	if (ifp->if_bpf)
+		bpf_mtap_af(ifp->if_bpf, dst->sa_family, m);
 #endif
 	ifp->if_opackets++;	
 	ifp->if_obytes += m->m_pkthdr.len;
diff --git a/sys/net/if_gre.c b/sys/net/if_gre.c
index 8310ff5404e..8b411fc95fe 100644
--- a/sys/net/if_gre.c
+++ b/sys/net/if_gre.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: if_gre.c,v 1.34 2005/06/08 06:35:04 henning Exp $ */
+/*      $OpenBSD: if_gre.c,v 1.35 2005/07/31 03:52:18 pascoe Exp $ */
 /*	$NetBSD: if_gre.c,v 1.9 1999/10/25 19:18:11 drochner Exp $ */
 
 /*
@@ -235,24 +235,8 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	m_tag_prepend(m, mtag);
 
 #if NBPFILTER >0
-	if (ifp->if_bpf) {
-		/*
-		 * We need to prepend the address family as a four
-		 * byte field.  Cons up a fake header to pacify bpf.
-		 * This is safe because bpf will only read from the
-		 * mbuf (i.e., it won't try to free it or keep a
-		 * pointer a to it).
-		 */
-		struct mbuf m0;
-		u_int32_t af = dst->sa_family;
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = 4;
-		m0.m_data = (char *) ⁡
-
-		bpf_mtap(ifp->if_bpf, &m0);
-	}
+	if (ifp->if_bpf)
+		bpf_mtap_af(ifp->if_bpf, dst->sa_family, m);
 #endif
 
 	if (sc->g_proto == IPPROTO_MOBILE) {
diff --git a/sys/net/if_loop.c b/sys/net/if_loop.c
index dc51a28c9b5..b4760546e43 100644
--- a/sys/net/if_loop.c
+++ b/sys/net/if_loop.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_loop.c,v 1.35 2005/06/12 06:23:43 henning Exp $	*/
+/*	$OpenBSD: if_loop.c,v 1.36 2005/07/31 03:52:18 pascoe Exp $	*/
 /*	$NetBSD: if_loop.c,v 1.15 1996/05/07 02:40:33 thorpej Exp $	*/
 
 /*
@@ -250,24 +250,8 @@ looutput(ifp, m, dst, rt)
 	 * looutput() is also called for SIMPLEX interfaces to duplicate
 	 * packets for local use. But don't dup them to bpf.
 	 */
-	if (ifp->if_bpf && (ifp->if_flags&IFF_LOOPBACK)) {
-		/*
-		 * We need to prepend the address family as
-		 * a four byte field.  Cons up a dummy header
-		 * to pacify bpf.  This is safe because bpf
-		 * will only read from the mbuf (i.e., it won't
-		 * try to free it or keep a pointer to it).
-		 */
-		struct mbuf m0;
-		u_int32_t af = htonl(dst->sa_family);
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = sizeof(af);
-		m0.m_data = (char *)⁡
-
-		bpf_mtap(ifp->if_bpf, &m0);
-	}
+	if (ifp->if_bpf && (ifp->if_flags & IFF_LOOPBACK))
+		bpf_mtap_af(ifp->if_bpf, dst->sa_family, m);
 #endif
 	m->m_pkthdr.rcvif = ifp;
 
diff --git a/sys/net/if_pflog.c b/sys/net/if_pflog.c
index d5370c1c7fa..548d0247c66 100644
--- a/sys/net/if_pflog.c
+++ b/sys/net/if_pflog.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_pflog.c,v 1.14 2005/05/27 20:17:31 dhartmei Exp $	*/
+/*	$OpenBSD: if_pflog.c,v 1.15 2005/07/31 03:52:18 pascoe Exp $	*/
 /*
  * The authors of this code are John Ioannidis (ji@tla.org),
  * Angelos D. Keromytis (kermit@csd.uch.gr) and 
@@ -180,11 +180,14 @@ pflog_packet(struct pfi_kif *kif, struct mbuf *m, sa_family_t af, u_int8_t dir,
 #if NBPFILTER > 0
 	struct ifnet *ifn;
 	struct pfloghdr hdr;
-	struct mbuf m1;
 
 	if (kif == NULL || m == NULL || rm == NULL || pd == NULL)
 		return (-1);
 
+	ifn = &(pflogif[0].sc_if);
+	if (!ifn->if_bpf)
+		return (0);
+
 	bzero(&hdr, sizeof(hdr));
 	hdr.length = PFLOG_REAL_HDRLEN;
 	hdr.af = af;
@@ -225,14 +228,7 @@ pflog_packet(struct pfi_kif *kif, struct mbuf *m, sa_family_t af, u_int8_t dir,
 	}
 #endif /* INET */
 
-	m1.m_next = m;
-	m1.m_len = PFLOG_HDRLEN;
-	m1.m_data = (char *) &hdr;
-
-	ifn = &(pflogif[0].sc_if);
-
-	if (ifn->if_bpf)
-		bpf_mtap(ifn->if_bpf, &m1);
+	bpf_mtap_hdr(ifn->if_bpf, (char *)&hdr, PFLOG_HDRLEN, m);
 #endif
 
 	return (0);
diff --git a/sys/net/if_trunk.c b/sys/net/if_trunk.c
index 8ca077eb43e..84b896281b7 100644
--- a/sys/net/if_trunk.c
+++ b/sys/net/if_trunk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_trunk.c,v 1.3 2005/05/27 22:57:13 reyk Exp $	*/
+/*	$OpenBSD: if_trunk.c,v 1.4 2005/07/31 03:52:18 pascoe Exp $	*/
 
 /*
  * Copyright (c) 2005 Reyk Floeter <reyk@vantronix.net>
@@ -669,15 +669,8 @@ trunk_input(struct ifnet *ifp, struct ether_header *eh, struct mbuf *m)
 	trifp = &tr->tr_ac.ac_if;
 
 #if NBPFILTER > 0
-	if (trifp->if_bpf) {
-		struct mbuf m0;
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = ETHER_HDR_LEN;
-		m0.m_data = (char *)eh;
-		bpf_mtap(trifp->if_bpf, &m0);
-	}
+	if (trifp->if_bpf)
+		bpf_mtap_hdr(trifp->if_bpf, (char *)eh, ETHER_HDR_LEN, m);
 #endif
 
 	error = (*tr->tr_input)(tr, tp, eh, m);
diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 376db014ef0..579128b1456 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vlan.c,v 1.58 2005/07/19 11:50:20 camield Exp $	*/
+/*	$OpenBSD: if_vlan.c,v 1.59 2005/07/31 03:52:18 pascoe Exp $	*/
 
 /*
  * Copyright 1998 Massachusetts Institute of Technology
@@ -301,21 +301,8 @@ vlan_input(eh, m)
 	m->m_pkthdr.len -= EVL_ENCAPLEN;
 
 #if NBPFILTER > 0
-	if (ifv->ifv_if.if_bpf) {
-		/*
-		 * Do the usual BPF fakery.  Note that we don't support
-		 * promiscuous mode here, since it would require the
-		 * drivers to know about VLANs and we're not ready for
-		 * that yet.
-		 */
-		struct mbuf m0;
-
-		m0.m_flags = 0;
-		m0.m_next = m;
-		m0.m_len = ETHER_HDR_LEN;
-		m0.m_data = (char *)eh;
-		bpf_mtap(ifv->ifv_if.if_bpf, &m0);
-	}
+	if (ifv->ifv_if.if_bpf)
+		bpf_mtap_hdr(ifv->ifv_if.if_bpf, (char *)eh, ETHER_HDR_LEN, m);
 #endif
 	ifv->ifv_if.if_ipackets++;
 	ether_input(&ifv->ifv_if, eh, m);