svn commit: r358566 - stable/11/sys/netinet6

[Bjoern A. Zeeb]

Author: bz
Date: Tue Mar  3 08:24:09 2020
New Revision: 358566
URL: https://svnweb.freebsd.org/changeset/base/358566

Log:
  MFC r358297: Fix IPv6 checksums when exthdrs are present.
  
      In two places in ip6_output we are doing (delayed) checksum calculations.
      The initial logic came from SCTP in r205075,205104 and later I copied
      and adjusted it for the TCP|UDP case in r235958.
      The problem was that the original SCTP offsets were already wrong for any
      case with extension headers present given IPv6 extension headers are not
      part of the pseudo checksum calculations.
      The later changes do not help in case there is checksum offloading as for
      extension headers (incl. fragments) we do currrently never offload as we
      have no infrastructure to know whether the NIC can handle these cases.
  
      Correct the offsets for delayed checksum calculations and properly handle
      mbuf flags.  In addition harmonize the almost identical duplicate code.
  
      While here eliminate the now unneeded variable hlen and add an always
      missing mtod() call in the 1-b and 3 cases after the introduction of
      the mb_unmapped_to_ext() calls. [Keep code in sync with head]
  
  Reported by:	Francis Dupont (fdupont isc.org)
  PR:		243675

Modified:
  stable/11/sys/netinet6/ip6_output.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/netinet6/ip6_output.c
==============================================================================
--- stable/11/sys/netinet6/ip6_output.c	Tue Mar  3 03:22:00 2020	(r358565)
+++ stable/11/sys/netinet6/ip6_output.c	Tue Mar  3 08:24:09 2020	(r358566)
@@ -209,6 +209,36 @@ in6_delayed_cksum(struct mbuf *m, uint32_t plen, u_sho
 		*(u_short *)mtodo(m, offset) = csum;
 }
 
+static int
+ip6_output_delayed_csum(struct mbuf *m, struct ifnet *ifp, int csum_flags,
+    int plen, int optlen, bool frag __unused)
+{
+
+	KASSERT((plen >= optlen), ("%s:%d: plen %d < optlen %d, m %p, ifp %p "
+	    "csum_flags %#x frag %d\n",
+	    __func__, __LINE__, plen, optlen, m, ifp, csum_flags, frag));
+
+	if ((csum_flags & CSUM_DELAY_DATA_IPV6) ||
+#ifdef SCTP
+	    (csum_flags & CSUM_SCTP_IPV6) ||
+#endif
+	    false) {
+		if (csum_flags & CSUM_DELAY_DATA_IPV6) {
+			in6_delayed_cksum(m, plen - optlen,
+			    sizeof(struct ip6_hdr) + optlen);
+			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
+		}
+#ifdef SCTP
+		if (csum_flags & CSUM_SCTP_IPV6) {
+			sctp_delayed_cksum(m, sizeof(struct ip6_hdr) + optlen);
+			m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
+		}
+#endif
+	}
+
+	return (0);
+}
+
 int
 ip6_fragment(struct ifnet *ifp, struct mbuf *m0, int hlen, u_char nextproto,
     int mtu, uint32_t id)
@@ -308,7 +338,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
 	struct ifnet *ifp, *origifp;
 	struct mbuf *m = m0;
 	struct mbuf *mprev;
-	int hlen, tlen, len;
+	int tlen, len;
 	struct route_in6 ip6route;
 	struct rtentry *rt = NULL;
 	struct sockaddr_in6 *dst, src_sa, dst_sa;
@@ -929,17 +959,10 @@ passout:
 	 * XXX-BZ  Need a framework to know when the NIC can handle it, even
 	 * with ext. hdrs.
 	 */
-	if (sw_csum & CSUM_DELAY_DATA_IPV6) {
-		sw_csum &= ~CSUM_DELAY_DATA_IPV6;
-		in6_delayed_cksum(m, plen, sizeof(struct ip6_hdr));
-	}
-#ifdef SCTP
-	if (sw_csum & CSUM_SCTP_IPV6) {
-		sw_csum &= ~CSUM_SCTP_IPV6;
-		sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
-	}
-#endif
-	m->m_pkthdr.csum_flags &= ifp->if_hwassist;
+	error = ip6_output_delayed_csum(m, ifp, sw_csum, plen, optlen, false);
+	if (error != 0)
+		goto bad;
+	/* XXX-BZ m->m_pkthdr.csum_flags &= ~ifp->if_hwassist; */
 	tlen = m->m_pkthdr.len;
 
 	if ((opt && (opt->ip6po_flags & IP6PO_DONTFRAG)) || tso)
@@ -1003,11 +1026,10 @@ passout:
 		 * fragment if possible.
 		 * Must be able to put at least 8 bytes per fragment.
 		 */
-		hlen = unfragpartlen;
 		if (mtu > IPV6_MAXPACKET)
 			mtu = IPV6_MAXPACKET;
 
-		len = (mtu - hlen - sizeof(struct ip6_frag)) & ~7;
+		len = (mtu - unfragpartlen - sizeof(struct ip6_frag)) & ~7;
 		if (len < 8) {
 			error = EMSGSIZE;
 			in6_ifstat_inc(ifp, ifs6_out_fragfail);
@@ -1019,16 +1041,11 @@ passout:
 		 * fragmented packets, then do it here.
 		 * XXX-BZ handle the hw offloading case.  Need flags.
 		 */
-		if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
-			in6_delayed_cksum(m, plen, hlen);
-			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
-		}
-#ifdef SCTP
-		if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
-			sctp_delayed_cksum(m, hlen);
-			m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
-		}
-#endif
+		error = ip6_output_delayed_csum(m, ifp, m->m_pkthdr.csum_flags,
+		    plen, optlen, true);
+		if (error != 0)
+			goto bad;
+
 		/*
 		 * Change the next header field of the last header in the
 		 * unfragmentable part.
@@ -1043,6 +1060,7 @@ passout:
 			nextproto = *mtod(exthdrs.ip6e_hbh, u_char *);
 			*mtod(exthdrs.ip6e_hbh, u_char *) = IPPROTO_FRAGMENT;
 		} else {
+			ip6 = mtod(m, struct ip6_hdr *);
 			nextproto = ip6->ip6_nxt;
 			ip6->ip6_nxt = IPPROTO_FRAGMENT;
 		}
@@ -1054,7 +1072,8 @@ passout:
 		 */
 		m0 = m;
 		id = htonl(ip6_randomid());
-		if ((error = ip6_fragment(ifp, m, hlen, nextproto, len, id)))
+		error = ip6_fragment(ifp, m, unfragpartlen, nextproto,len, id);
+		if (error != 0)
 			goto sendorfree;
 
 		in6_ifstat_inc(ifp, ifs6_out_fragok);