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Date:      Fri, 15 Nov 2019 21:44:17 +0000 (UTC)
From:      "Bjoern A. Zeeb" <bz@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r354749 - in head/sys: netinet netinet6 netipsec
Message-ID:  <201911152144.xAFLiHop001392@repo.freebsd.org>
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Author: bz
Date: Fri Nov 15 21:44:17 2019
New Revision: 354749
URL: https://svnweb.freebsd.org/changeset/base/354749

Log:
  netinet*: replace IP6_EXTHDR_GET()
  
  In a few places we have IP6_EXTHDR_GET() left in upper layer protocols.
  The IP6_EXTHDR_GET() macro might perform an m_pulldown() in case the data
  fragment is not contiguous.
  
  Convert these last remaining instances into m_pullup()s instead.
  In CARP, for example, we will a few lines later call m_pullup() anyway,
  the IPsec code coming from OpenBSD would otherwise have done the m_pullup()
  and are copying the data a bit later anyway, so pulling it in seems no
  better or worse.
  
  Note: this leaves very few m_pulldown() cases behind in the tree and we
  might want to consider removing them as well to make mbuf management
  easier again on a path to variable size mbufs, especially given
  m_pulldown() still has an issue not re-checking M_WRITEABLE().
  
  Reviewed by:	gallatin
  MFC after:	8 weeks
  Sponsored by:	Netflix
  Differential Revision:	https://reviews.freebsd.org/D22335

Modified:
  head/sys/netinet/ip_carp.c
  head/sys/netinet6/sctp6_usrreq.c
  head/sys/netipsec/xform_ah.c
  head/sys/netipsec/xform_esp.c

Modified: head/sys/netinet/ip_carp.c
==============================================================================
--- head/sys/netinet/ip_carp.c	Fri Nov 15 21:40:40 2019	(r354748)
+++ head/sys/netinet/ip_carp.c	Fri Nov 15 21:44:17 2019	(r354749)
@@ -567,12 +567,13 @@ carp6_input(struct mbuf **mp, int *offp, int proto)
 
 	/* verify that we have a complete carp packet */
 	len = m->m_len;
-	IP6_EXTHDR_GET(ch, struct carp_header *, m, *offp, sizeof(*ch));
-	if (ch == NULL) {
+	m = m_pullup(m, *offp + sizeof(*ch));
+	if (m == NULL) {
 		CARPSTATS_INC(carps_badlen);
 		CARP_DEBUG("%s: packet size %u too small\n", __func__, len);
 		return (IPPROTO_DONE);
 	}
+	ch = (struct carp_header *)(mtod(m, caddr_t) + *offp);
 
 
 	/* verify the CARP checksum */

Modified: head/sys/netinet6/sctp6_usrreq.c
==============================================================================
--- head/sys/netinet6/sctp6_usrreq.c	Fri Nov 15 21:40:40 2019	(r354748)
+++ head/sys/netinet6/sctp6_usrreq.c	Fri Nov 15 21:44:17 2019	(r354749)
@@ -103,13 +103,13 @@ sctp6_input_with_port(struct mbuf **i_pak, int *offp, 
 	SCTP_STAT_INCR_COUNTER64(sctps_inpackets);
 	/* Get IP, SCTP, and first chunk header together in the first mbuf. */
 	offset = iphlen + sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr);
-	ip6 = mtod(m, struct ip6_hdr *);
-	IP6_EXTHDR_GET(sh, struct sctphdr *, m, iphlen,
-	    (int)(sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr)));
-	if (sh == NULL) {
+	m = m_pullup(m, offset);
+	if (m == NULL) {
 		SCTP_STAT_INCR(sctps_hdrops);
 		return (IPPROTO_DONE);
 	}
+	ip6 = mtod(m, struct ip6_hdr *);
+	sh = (struct sctphdr *)(mtod(m, caddr_t) + iphlen);
 	ch = (struct sctp_chunkhdr *)((caddr_t)sh + sizeof(struct sctphdr));
 	offset -= sizeof(struct sctp_chunkhdr);
 	memset(&src, 0, sizeof(struct sockaddr_in6));

Modified: head/sys/netipsec/xform_ah.c
==============================================================================
--- head/sys/netipsec/xform_ah.c	Fri Nov 15 21:40:40 2019	(r354748)
+++ head/sys/netipsec/xform_ah.c	Fri Nov 15 21:44:17 2019	(r354749)
@@ -575,14 +575,14 @@ ah_input(struct mbuf *m, struct secasvar *sav, int ski
 	/* Figure out header size. */
 	rplen = HDRSIZE(sav);
 
-	/* XXX don't pullup, just copy header */
-	IP6_EXTHDR_GET(ah, struct newah *, m, skip, rplen);
-	if (ah == NULL) {
+	m = m_pullup(m, skip + rplen);
+	if (m == NULL) {
 		DPRINTF(("ah_input: cannot pullup header\n"));
 		AHSTAT_INC(ahs_hdrops);		/*XXX*/
 		error = ENOBUFS;
 		goto bad;
 	}
+	ah = (struct newah *)(mtod(m, caddr_t) + skip);
 
 	/* Check replay window, if applicable. */
 	SECASVAR_LOCK(sav);

Modified: head/sys/netipsec/xform_esp.c
==============================================================================
--- head/sys/netipsec/xform_esp.c	Fri Nov 15 21:40:40 2019	(r354748)
+++ head/sys/netipsec/xform_esp.c	Fri Nov 15 21:44:17 2019	(r354749)
@@ -307,8 +307,15 @@ esp_input(struct mbuf *m, struct secasvar *sav, int sk
 		ESPSTAT_INC(esps_badilen);
 		goto bad;
 	}
-	/* XXX don't pullup, just copy header */
-	IP6_EXTHDR_GET(esp, struct newesp *, m, skip, sizeof (struct newesp));
+
+	m = m_pullup(m, skip + sizeof(*esp));
+	if (m == NULL) {
+		DPRINTF(("%s: cannot pullup header\n", __func__));
+		ESPSTAT_INC(esps_hdrops);	/*XXX*/
+		error = ENOBUFS;
+		goto bad;
+	}
+	esp = (struct newesp *)(mtod(m, caddr_t) + skip);
 
 	esph = sav->tdb_authalgxform;
 	espx = sav->tdb_encalgxform;

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