svn commit: r238495 - stable/8/sys/netinet6

[Bjoern A. Zeeb]

Author: bz
Date: Sun Jul 15 18:20:09 2012
New Revision: 238495
URL: http://svn.freebsd.org/changeset/base/238495

Log:
  MFC r238248:
  
   Implement handling of "atomic fragements" as outlined in
   draft-gont-6man-ipv6-atomic-fragments to mitigate one class of
   possible fragmentation-based attacks.

Modified:
  stable/8/sys/netinet6/frag6.c
Directory Properties:
  stable/8/sys/   (props changed)

Modified: stable/8/sys/netinet6/frag6.c
==============================================================================
--- stable/8/sys/netinet6/frag6.c	Sun Jul 15 18:14:04 2012	(r238494)
+++ stable/8/sys/netinet6/frag6.c	Sun Jul 15 18:20:09 2012	(r238495)
@@ -221,6 +221,19 @@ frag6_input(struct mbuf **mp, int *offp,
 	/* offset now points to data portion */
 	offset += sizeof(struct ip6_frag);
 
+	/*
+	 * XXX-BZ RFC XXXX (draft-gont-6man-ipv6-atomic-fragments)
+	 * Handle "atomic" fragments (offset and m bit set to 0) upfront,
+	 * unrelated to any reassembly.  Just skip the fragment header.
+	 */
+	if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
+		/* XXX-BZ we want dedicated counters for this. */
+		V_ip6stat.ip6s_reassembled++;
+		in6_ifstat_inc(dstifp, ifs6_reass_ok);
+		*offp = offset;
+		return (ip6f->ip6f_nxt);
+	}
+
 	IP6Q_LOCK();
 
 	/*