During fragment reassembly, mbuf chains with packet headers were

created.  Add a new function m_removehdr() do convert packet header
mbufs within the chain to regular mbufs.  Assert that the mbuf at
the beginning of the chain has a packet header.
found by Maxime Villard in NetBSD; from markus@; OK claudio@

6 files changed, 57 insertions, 22 deletions

diff --git a/share/man/man9/mbuf.9 b/share/man/man9/mbuf.9
index d70a070fc0a..d08f1d246e0 100644
--- a/share/man/man9/mbuf.9
+++ b/share/man/man9/mbuf.9
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: mbuf.9,v 1.111 2018/02/11 00:27:10 dlg Exp $
+.\"     $OpenBSD: mbuf.9,v 1.112 2018/09/10 12:47:02 bluhm Exp $
 .\"
 .\" Copyright (c) 2001 Jean-Jacques Bernard-Gundol <jjbg@openbsd.org>
 .\" All rights reserved.
@@ -25,7 +25,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: February 11 2018 $
+.Dd $Mdocdate: September 10 2018 $
 .Dt MGET 9
 .Os
 .Sh NAME
@@ -35,6 +35,7 @@
 .Nm MGET ,
 .Nm m_getclr ,
 .Nm m_gethdr ,
+.Nm m_removehdr ,
 .Nm m_resethdr ,
 .Nm MGETHDR ,
 .Nm m_prepend ,
@@ -79,6 +80,8 @@
 .Ft struct mbuf *
 .Fn m_getclr "int how" "int type"
 .Ft void
+.Fn m_removehdr "struct mbuf *m"
+.Ft void
 .Fn m_resethdr "struct mbuf *m"
 .Ft struct mbuf *
 .Fn m_gethdr "int how" "int type"
@@ -486,11 +489,19 @@ See
 .Fn m_get
 for a description of
 .Fa how .
+.It Fn m_removehdr "struct mbuf *m"
+Convert a mbuf with packet header to one without.
+Delete all
+.Xr pf 4
+data and all tags attached to a
+.Fa mbuf .
+Keep the data and mbuf chain, clear the packet header.
 .It Fn m_resethdr "struct mbuf *m"
-Deletes all
+Delete all
 .Xr pf 4
 data and all tags attached to a
 .Fa mbuf .
+Keep the data and mbuf chain, initialize the packet header.
 .It Fn m_gethdr "int how" "int type"
 Return a pointer to an mbuf of the type specified after initializing
 it to contain a packet header.
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index 5bb5c624978..2dda4b56292 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_mbuf.c,v 1.256 2018/03/18 21:25:14 deraadt Exp $	*/
+/*	$OpenBSD: uipc_mbuf.c,v 1.257 2018/09/10 12:47:02 bluhm Exp $	*/
 /*	$NetBSD: uipc_mbuf.c,v 1.15.4.1 1996/06/13 17:11:44 cgd Exp $	*/
 
 /*
@@ -291,15 +291,9 @@ m_inithdr(struct mbuf *m)
 	return (m);
 }
 
-void
-m_resethdr(struct mbuf *m)
+static inline void
+m_clearhdr(struct mbuf *m)
 {
-	int len = m->m_pkthdr.len;
-	u_int8_t loopcnt = m->m_pkthdr.ph_loopcnt;
-
-	KASSERT(m->m_flags & M_PKTHDR);
-	m->m_flags &= (M_EXT|M_PKTHDR|M_EOR|M_EXTWR|M_ZEROIZE);
-
 	/* delete all mbuf tags to reset the state */
 	m_tag_delete_chain(m);
 
@@ -307,8 +301,27 @@ m_resethdr(struct mbuf *m)
 	pf_mbuf_unlink_state_key(m);
 #endif	/* NPF > 0 */
 
-	/* like m_inithdr(), but keep any associated data and mbufs */
 	memset(&m->m_pkthdr, 0, sizeof(m->m_pkthdr));
+}
+
+void
+m_removehdr(struct mbuf *m)
+{
+	KASSERT(m->m_flags & M_PKTHDR);
+	m_clearhdr(m);
+	m->m_flags &= ~M_PKTHDR;
+}
+
+void
+m_resethdr(struct mbuf *m)
+{
+	int len = m->m_pkthdr.len;
+	u_int8_t loopcnt = m->m_pkthdr.ph_loopcnt;
+
+	KASSERT(m->m_flags & M_PKTHDR);
+	m->m_flags &= (M_EXT|M_PKTHDR|M_EOR|M_EXTWR|M_ZEROIZE);
+	m_clearhdr(m);
+	/* like m_inithdr(), but keep any associated data and mbufs */
 	m->m_pkthdr.pf.prio = IFQ_DEFPRIO;
 	m->m_pkthdr.len = len;
 	m->m_pkthdr.ph_loopcnt = loopcnt;
diff --git a/sys/net/pf_norm.c b/sys/net/pf_norm.c
index a328c9be7cd..d60dd43442b 100644
--- a/sys/net/pf_norm.c
+++ b/sys/net/pf_norm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pf_norm.c,v 1.214 2018/09/10 11:37:26 bluhm Exp $ */
+/*	$OpenBSD: pf_norm.c,v 1.215 2018/09/10 12:47:02 bluhm Exp $ */
 
 /*
  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
@@ -743,6 +743,7 @@ pf_join_fragment(struct pf_fragment *frag)
 			m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 		pool_put(&pf_frent_pl, frent);
 		pf_nfrents--;
+		m_removehdr(m2);
 		m_cat(m, m2);
 	}
 
@@ -805,8 +806,10 @@ pf_reassemble(struct mbuf **m0, int dir, u_short *reason)
 	m = *m0 = pf_join_fragment(frag);
 	frag = NULL;
 
-	if (m->m_flags & M_PKTHDR) {
+	{
 		int plen = 0;
+
+		KASSERT(m->m_flags & M_PKTHDR);
 		for (m = *m0; m; m = m->m_next)
 			plen += m->m_len;
 		m = *m0;
@@ -904,8 +907,10 @@ pf_reassemble6(struct mbuf **m0, struct ip6_frag *fraghdr,
 	if (frag6_deletefraghdr(m, hdrlen) != 0)
 		goto fail;
 
-	if (m->m_flags & M_PKTHDR) {
+	{
 		int plen = 0;
+
+		KASSERT(m->m_flags & M_PKTHDR);
 		for (m = *m0; m; m = m->m_next)
 			plen += m->m_len;
 		m = *m0;
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 4585b7f8b06..3e9bab33b36 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_input.c,v 1.338 2018/07/10 11:34:12 mpi Exp $	*/
+/*	$OpenBSD: ip_input.c,v 1.339 2018/09/10 12:47:02 bluhm Exp $	*/
 /*	$NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $	*/
 
 /*
@@ -947,6 +947,7 @@ insert:
 		nq = LIST_NEXT(q, ipqe_q);
 		pool_put(&ipqent_pool, q);
 		ip_frags--;
+		m_removehdr(t);
 		m_cat(m, t);
 	}
 
@@ -963,9 +964,10 @@ insert:
 	pool_put(&ipq_pool, fp);
 	m->m_len += (ip->ip_hl << 2);
 	m->m_data -= (ip->ip_hl << 2);
-	/* some debugging cruft by sklower, below, will go away soon */
-	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
+	{
 		int plen = 0;
+
+		KASSERT(m->m_flags & M_PKTHDR);
 		for (t = m; t; t = t->m_next)
 			plen += t->m_len;
 		m->m_pkthdr.len = plen;
diff --git a/sys/netinet6/frag6.c b/sys/netinet6/frag6.c
index 38631a8159a..5e8721f15e2 100644
--- a/sys/netinet6/frag6.c
+++ b/sys/netinet6/frag6.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: frag6.c,v 1.83 2018/08/22 19:48:48 cheloha Exp $	*/
+/*	$OpenBSD: frag6.c,v 1.84 2018/09/10 12:47:02 bluhm Exp $	*/
 /*	$KAME: frag6.c,v 1.40 2002/05/27 21:40:31 itojun Exp $	*/
 
 /*
@@ -400,6 +400,7 @@ frag6_input(struct mbuf **mp, int *offp, int proto, int af)
 			t = t->m_next;
 		t->m_next = af6->ip6af_m;
 		m_adj(t->m_next, af6->ip6af_offset);
+		m_removehdr(t->m_next);
 		pool_put(&ip6af_pool, af6);
 	}
 
@@ -430,8 +431,10 @@ frag6_input(struct mbuf **mp, int *offp, int proto, int af)
 
 	pool_put(&ip6q_pool, q6);
 
-	if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
+	{
 		int plen = 0;
+
+		KASSERT(m->m_flags & M_PKTHDR);
 		for (t = m; t; t = t->m_next)
 			plen += t->m_len;
 		m->m_pkthdr.len = plen;
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 8c2f21b690b..8a9df640faf 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbuf.h,v 1.236 2018/07/10 09:28:27 henning Exp $	*/
+/*	$OpenBSD: mbuf.h,v 1.237 2018/09/10 12:47:02 bluhm Exp $	*/
 /*	$NetBSD: mbuf.h,v 1.19 1996/02/09 18:25:14 christos Exp $	*/
 
 /*
@@ -441,6 +441,7 @@ struct	mbuf *m_get(int, int);
 struct	mbuf *m_getclr(int, int);
 struct	mbuf *m_gethdr(int, int);
 struct	mbuf *m_inithdr(struct mbuf *);
+void	m_removehdr(struct mbuf *);
 void	m_resethdr(struct mbuf *);
 int	m_defrag(struct mbuf *, int);
 struct	mbuf *m_prepend(struct mbuf *, int, int);