]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/netinet6/frag6.c
xnu-2422.1.72.tar.gz
[apple/xnu.git] / bsd / netinet6 / frag6.c
index 020c3d340f955707d94f173530411736a8e67fd7..6a92d73808983ea2932e9d5de7777b1d3fe4e7a9 100644 (file)
@@ -1,4 +1,33 @@
-/*     $KAME: frag6.c,v 1.23 2000/02/28 16:18:11 itojun Exp $  */
+/*
+ * Copyright (c) 2000-2013 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ * 
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ */
+
+/*     $FreeBSD: src/sys/netinet6/frag6.c,v 1.2.2.5 2001/07/03 11:01:50 ume Exp $      */
+/*     $KAME: frag6.c,v 1.31 2001/05/17 13:45:34 jinmei Exp $  */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -32,6 +61,7 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/malloc.h>
+#include <sys/mcache.h>
 #include <sys/mbuf.h>
 #include <sys/domain.h>
 #include <sys/protosw.h>
 #include <sys/kernel.h>
 #include <sys/syslog.h>
 #include <kern/queue.h>
+#include <kern/locks.h>
 
 #include <net/if.h>
 #include <net/route.h>
 
 #include <netinet/in.h>
 #include <netinet/in_var.h>
+#include <netinet/ip.h>
 #include <netinet/ip6.h>
 #include <netinet6/ip6_var.h>
-#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3) && !defined(__OpenBSD__) && !(defined(__bsdi__) && _BSDI_VERSION >= 199802) && !defined(__APPLE__)
-#include <netinet6/in6_pcb.h>
-#endif
 #include <netinet/icmp6.h>
 
 #include <net/net_osdep.h>
+#include <dev/random/randomdev.h>
 
 /*
  * Define it to get a correct behavior on per-interface statistics.
- * You will need to perform an extra routing table lookup, per fragment,
- * to do it.  This may, or may not be, a performance hit.
  */
 #define IN6_IFSTAT_STRICT
 
-static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
-static void frag6_deq __P((struct ip6asfrag *));
-static void frag6_insque __P((struct ip6q *, struct ip6q *));
-static void frag6_remque __P((struct ip6q *));
-static void frag6_freef __P((struct ip6q *));
+MBUFQ_HEAD(fq6_head);
+
+static void frag6_save_context(struct mbuf *, int);
+static void frag6_scrub_context(struct mbuf *);
+static int frag6_restore_context(struct mbuf *);
+
+static void frag6_icmp6_paramprob_error(struct fq6_head *);
+static void frag6_icmp6_timeex_error(struct fq6_head *);
+
+static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
+static void frag6_deq(struct ip6asfrag *);
+static void frag6_insque(struct ip6q *, struct ip6q *);
+static void frag6_remque(struct ip6q *);
+static void frag6_freef(struct ip6q *, struct fq6_head *, struct fq6_head *);
+
+static int frag6_timeout_run;          /* frag6 timer is scheduled to run */
+static void frag6_timeout(void *);
+static void frag6_sched_timeout(void);
+
+static struct ip6q *ip6q_alloc(int);
+static void ip6q_free(struct ip6q *);
+static void ip6q_updateparams(void);
+static struct ip6asfrag *ip6af_alloc(int);
+static void ip6af_free(struct ip6asfrag *);
+
+decl_lck_mtx_data(static, ip6qlock);
+static lck_attr_t      *ip6qlock_attr;
+static lck_grp_t       *ip6qlock_grp;
+static lck_grp_attr_t  *ip6qlock_grp_attr;
+
+/* IPv6 fragment reassembly queues (protected by ip6qlock) */
+static struct ip6q ip6q;               /* ip6 reassembly queues */
+static int ip6_maxfragpackets;         /* max packets in reass queues */
+static u_int32_t frag6_nfragpackets;   /* # of packets in reass queues */
+static int ip6_maxfrags;               /* max fragments in reass queues */
+static u_int32_t frag6_nfrags;         /* # of fragments in reass queues */
+static u_int32_t ip6q_limit;           /* ip6q allocation limit */
+static u_int32_t ip6q_count;           /* current # of allocated ip6q's */
+static u_int32_t ip6af_limit;          /* ip6asfrag allocation limit */
+static u_int32_t ip6af_count;          /* current # of allocated ip6asfrag's */
+
+static int sysctl_maxfragpackets SYSCTL_HANDLER_ARGS;
+static int sysctl_maxfrags SYSCTL_HANDLER_ARGS;
+
+SYSCTL_DECL(_net_inet6_ip6);
+
+SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &ip6_maxfragpackets, 0,
+    sysctl_maxfragpackets, "I",
+    "Maximum number of IPv6 fragment reassembly queue entries");
+
+SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, fragpackets,
+    CTLFLAG_RD | CTLFLAG_LOCKED, &frag6_nfragpackets, 0,
+    "Current number of IPv6 fragment reassembly queue entries");
+
+SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &ip6_maxfrags, 0,
+    sysctl_maxfrags, "I", "Maximum number of IPv6 fragments allowed");
 
-int frag6_doing_reass;
-u_int frag6_nfragpackets;
-struct ip6q ip6q;      /* ip6 reassemble queue */
+/*
+ * Initialise reassembly queue and fragment identifier.
+ */
+void
+frag6_init(void)
+{
+       /* ip6q_alloc() uses mbufs for IPv6 fragment queue structures */
+       _CASSERT(sizeof (struct ip6q) <= _MLEN);
+       /* ip6af_alloc() uses mbufs for IPv6 fragment queue structures */
+       _CASSERT(sizeof (struct ip6asfrag) <= _MLEN);
+
+       /* IPv6 fragment reassembly queue lock */
+       ip6qlock_grp_attr  = lck_grp_attr_alloc_init();
+       ip6qlock_grp = lck_grp_alloc_init("ip6qlock", ip6qlock_grp_attr);
+       ip6qlock_attr = lck_attr_alloc_init();
+       lck_mtx_init(&ip6qlock, ip6qlock_grp, ip6qlock_attr);
+
+       lck_mtx_lock(&ip6qlock);
+       /* Initialize IPv6 reassembly queue. */
+       ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
 
-/* FreeBSD tweak */
-#if !defined(M_FTABLE) && (defined(__FreeBSD__) && __FreeBSD__ >= 3)
-MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
-#endif
+       /* same limits as IPv4 */
+       ip6_maxfragpackets = nmbclusters / 32;
+       ip6_maxfrags = ip6_maxfragpackets * 2;
+       ip6q_updateparams();
+       lck_mtx_unlock(&ip6qlock);
+}
 
-#ifndef offsetof               /* XXX */
-#define        offsetof(type, member)  ((size_t)(&((type *)0)->member))
-#endif
+static void
+frag6_save_context(struct mbuf *m, int val)
+{
+       m->m_pkthdr.pkt_hdr = (void *)(uintptr_t)val;
+}
+
+static void
+frag6_scrub_context(struct mbuf *m)
+{
+       m->m_pkthdr.pkt_hdr = NULL;
+}
+
+static int
+frag6_restore_context(struct mbuf *m)
+{
+       return ((int)m->m_pkthdr.pkt_hdr);
+}
 
 /*
- * Initialise reassembly queue and fragment identifier.
+ * Send any deferred ICMP param problem error messages; caller must not be
+ * holding ip6qlock and is expected to have saved the per-packet parameter
+ * value via frag6_save_context().
  */
-void
-frag6_init()
+static void
+frag6_icmp6_paramprob_error(struct fq6_head *diq6)
+{
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_NOTOWNED);
+
+       if (!MBUFQ_EMPTY(diq6)) {
+               struct mbuf *merr, *merr_tmp;
+               int param;
+               MBUFQ_FOREACH_SAFE(merr, diq6, merr_tmp) {
+                       MBUFQ_REMOVE(diq6, merr);
+                       MBUFQ_NEXT(merr) = NULL;
+                       param = frag6_restore_context(merr);
+                       frag6_scrub_context(merr);
+                       icmp6_error(merr, ICMP6_PARAM_PROB,
+                           ICMP6_PARAMPROB_HEADER, param);
+               }
+       }
+}
+
+/*
+ * Send any deferred ICMP time exceeded error messages;
+ * caller must not be holding ip6qlock.
+ */
+static void
+frag6_icmp6_timeex_error(struct fq6_head *diq6)
 {
-       struct timeval tv;
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_NOTOWNED);
 
-       /*
-        * in many cases, random() here does NOT return random number
-        * as initialization during bootstrap time occur in fixed order.
-        */
-       microtime(&tv);
-       ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
-       ip6_id = random() ^ tv.tv_usec;
+       if (!MBUFQ_EMPTY(diq6)) {
+               struct mbuf *m, *m_tmp;
+               MBUFQ_FOREACH_SAFE(m, diq6, m_tmp) {
+                       MBUFQ_REMOVE(diq6, m);
+                       MBUFQ_NEXT(m) = NULL;
+                       icmp6_error(m, ICMP6_TIME_EXCEEDED,
+                           ICMP6_TIME_EXCEED_REASSEMBLY, 0);
+               }
+       }
 }
 
 /*
@@ -132,10 +273,9 @@ frag6_init()
  * Fragment input
  */
 int
-frag6_input(mp, offp, proto)
-       struct mbuf **mp;
-       int *offp, proto;
+frag6_input(struct mbuf **mp, int *offp, int proto)
 {
+#pragma unused(proto)
        struct mbuf *m = *mp, *t;
        struct ip6_hdr *ip6;
        struct ip6_frag *ip6f;
@@ -144,56 +284,54 @@ frag6_input(mp, offp, proto)
        int offset = *offp, nxt, i, next;
        int first_frag = 0;
        int fragoff, frgpartlen;        /* must be larger than u_int16_t */
-       struct ifnet *dstifp;
-#ifdef IN6_IFSTAT_STRICT
-       static struct route_in6 ro;
-       struct sockaddr_in6 *dst;
-#endif
+       struct ifnet *dstifp = NULL;
+       u_int8_t ecn, ecn0;
+       uint32_t csum, csum_flags;
+       struct fq6_head diq6;
+       int locked = 0;
+
+       VERIFY(m->m_flags & M_PKTHDR);
+
+       MBUFQ_INIT(&diq6);      /* for deferred ICMP param problem errors */
+
+       /* Expect 32-bit aligned data pointer on strict-align platforms */
+       MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 
        ip6 = mtod(m, struct ip6_hdr *);
 #ifndef PULLDOWN_TEST
-       IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
+       IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), goto done);
        ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
 #else
        IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
        if (ip6f == NULL)
-               return IPPROTO_DONE;
+               goto done;
 #endif
 
-       dstifp = NULL;
 #ifdef IN6_IFSTAT_STRICT
        /* find the destination interface of the packet. */
-       dst = (struct sockaddr_in6 *)&ro.ro_dst;
-       if (ro.ro_rt
-        && ((ro.ro_rt->rt_flags & RTF_UP) == 0
-         || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
-               RTFREE(ro.ro_rt);
-               ro.ro_rt = (struct rtentry *)0;
-       }
-       if (ro.ro_rt == NULL) {
-               bzero(dst, sizeof(*dst));
-               dst->sin6_family = AF_INET6;
-               dst->sin6_len = sizeof(struct sockaddr_in6);
-               dst->sin6_addr = ip6->ip6_dst;
-       }
-#ifndef __bsdi__
-       rtalloc((struct route *)&ro);
-#else
-       rtcalloc((struct route *)&ro);
-#endif
-       if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
-               dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
-#else
-       /* we are violating the spec, this is not the destination interface */
-       if ((m->m_flags & M_PKTHDR) != 0)
+       if (m->m_pkthdr.pkt_flags & PKTF_IFAINFO) {
+               uint32_t idx;
+
+               if (ip6_getdstifaddr_info(m, &idx, NULL) == 0) {
+                       if (idx > 0 && idx <= if_index) {
+                               ifnet_head_lock_shared();
+                               dstifp = ifindex2ifnet[idx];
+                               ifnet_head_done();
+                       }
+               }
+       }
+#endif /* IN6_IFSTAT_STRICT */
+
+       /* we are violating the spec, this may not be the dst interface */
+       if (dstifp == NULL)
                dstifp = m->m_pkthdr.rcvif;
-#endif
 
        /* jumbo payload can't contain a fragment header */
        if (ip6->ip6_plen == 0) {
                icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
                in6_ifstat_inc(dstifp, ifs6_reass_fail);
-               return IPPROTO_DONE;
+               m = NULL;
+               goto done;
        }
 
        /*
@@ -204,19 +342,79 @@ frag6_input(mp, offp, proto)
         */
        if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
            (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
-               icmp6_error(m, ICMP6_PARAM_PROB,
-                           ICMP6_PARAMPROB_HEADER,
-                           offsetof(struct ip6_hdr, ip6_plen));
+               icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
+                   offsetof(struct ip6_hdr, ip6_plen));
                in6_ifstat_inc(dstifp, ifs6_reass_fail);
-               return IPPROTO_DONE;
+               m = NULL;
+               goto done;
+       }
+
+       /* If ip6_maxfragpackets or ip6_maxfrags is 0, never accept fragments */
+       if (ip6_maxfragpackets == 0 || ip6_maxfrags == 0) {
+               ip6stat.ip6s_fragments++;
+               ip6stat.ip6s_fragdropped++;
+               in6_ifstat_inc(dstifp, ifs6_reass_fail);
+               m_freem(m);
+               m = NULL;
+               goto done;
        }
 
-       ip6stat.ip6s_fragments++;
-       in6_ifstat_inc(dstifp, ifs6_reass_reqd);
-       
        /* offset now points to data portion */
        offset += sizeof(struct ip6_frag);
 
+       /*
+        * Leverage partial checksum offload for simple UDP/IP fragments,
+        * as that is the most common case.
+        *
+        * Perform 1's complement adjustment of octets that got included/
+        * excluded in the hardware-calculated checksum value.
+        */
+       if (ip6f->ip6f_nxt == IPPROTO_UDP &&
+           offset == (sizeof (*ip6) + sizeof (*ip6f)) &&
+           (m->m_pkthdr.csum_flags &
+           (CSUM_DATA_VALID | CSUM_PARTIAL | CSUM_PSEUDO_HDR)) ==
+           (CSUM_DATA_VALID | CSUM_PARTIAL)) {
+               uint32_t start;
+
+               start = m->m_pkthdr.csum_rx_start;
+               csum = m->m_pkthdr.csum_rx_val;
+
+               if (start != offset) {
+                       uint16_t s, d;
+
+                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) {
+                               s = ip6->ip6_src.s6_addr16[1];
+                               ip6->ip6_src.s6_addr16[1] = 0 ;
+                       }
+                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) {
+                               d = ip6->ip6_dst.s6_addr16[1];
+                               ip6->ip6_dst.s6_addr16[1] = 0;
+                       }
+
+                       /* callee folds in sum */
+                       csum = m_adj_sum16(m, start, offset, csum);
+
+                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
+                               ip6->ip6_src.s6_addr16[1] = s;
+                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
+                               ip6->ip6_dst.s6_addr16[1] = d;
+
+               }
+               csum_flags = m->m_pkthdr.csum_flags;
+       } else {
+               csum = 0;
+               csum_flags = 0;
+       }
+
+       /* Invalidate checksum */
+       m->m_pkthdr.csum_flags &= ~CSUM_DATA_VALID;
+
+       ip6stat.ip6s_fragments++;
+       in6_ifstat_inc(dstifp, ifs6_reass_reqd);
+
+       lck_mtx_lock(&ip6qlock);
+       locked = 1;
+
        for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
                if (ip6f->ip6f_ident == q6->ip6q_ident &&
                    IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
@@ -228,38 +426,37 @@ frag6_input(mp, offp, proto)
                 * the first fragment to arrive, create a reassembly queue.
                 */
                first_frag = 1;
-               frag6_nfragpackets++;
 
-               /*
-                * Enforce upper bound on number of fragmented packets
-                * for which we attempt reassembly;
-                * If maxfrag is 0, never accept fragments.
-                * If maxfrag is -1, accept all fragments without limitation.
-                */
-               if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) {
-                       ip6stat.ip6s_fragoverflow++;
-                       in6_ifstat_inc(dstifp, ifs6_reass_fail);
-                       frag6_freef(ip6q.ip6q_prev);
-               }
-               q6 = (struct ip6q *)_MALLOC(sizeof(struct ip6q), M_FTABLE,
-                       M_DONTWAIT);
+               q6 = ip6q_alloc(M_DONTWAIT);
                if (q6 == NULL)
                        goto dropfrag;
-               bzero(q6, sizeof(*q6));
 
                frag6_insque(q6, &ip6q);
+               frag6_nfragpackets++;
 
                /* ip6q_nxt will be filled afterwards, from 1st fragment */
                q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
-#if notyet
+#ifdef notyet
                q6->ip6q_nxtp   = (u_char *)nxtp;
 #endif
                q6->ip6q_ident  = ip6f->ip6f_ident;
-               q6->ip6q_arrive = 0; /* Is it used anywhere? */
-               q6->ip6q_ttl    = IPV6_FRAGTTL;
+               q6->ip6q_ttl    = IPV6_FRAGTTL;
                q6->ip6q_src    = ip6->ip6_src;
                q6->ip6q_dst    = ip6->ip6_dst;
+               q6->ip6q_ecn    =
+                   (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
                q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
+
+               q6->ip6q_nfrag = 0;
+
+               /*
+                * If the first fragment has valid checksum offload
+                * info, the rest of fragments are eligible as well.
+                */
+               if (csum_flags != 0) {
+                       q6->ip6q_csum = csum;
+                       q6->ip6q_csum_flags = csum_flags;
+               }
        }
 
        /*
@@ -268,8 +465,8 @@ frag6_input(mp, offp, proto)
         */
        fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
        if (fragoff == 0) {
-               q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
-                       - sizeof(struct ip6_frag);
+               q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
+                   sizeof(struct ip6_frag);
                q6->ip6q_nxt = ip6f->ip6f_nxt;
        }
 
@@ -282,17 +479,22 @@ frag6_input(mp, offp, proto)
        if (q6->ip6q_unfrglen >= 0) {
                /* The 1st fragment has already arrived. */
                if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
+                       lck_mtx_unlock(&ip6qlock);
+                       locked = 0;
                        icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
-                                   offset - sizeof(struct ip6_frag) +
-                                       offsetof(struct ip6_frag, ip6f_offlg));
-                       return(IPPROTO_DONE);
+                           offset - sizeof(struct ip6_frag) +
+                           offsetof(struct ip6_frag, ip6f_offlg));
+                       m = NULL;
+                       goto done;
                }
-       }
-       else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
+       } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
+               lck_mtx_unlock(&ip6qlock);
+               locked = 0;
                icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
-                           offset - sizeof(struct ip6_frag) +
-                               offsetof(struct ip6_frag, ip6f_offlg));
-               return(IPPROTO_DONE);
+                   offset - sizeof(struct ip6_frag) +
+                   offsetof(struct ip6_frag, ip6f_offlg));
+               m = NULL;
+               goto done;
        }
        /*
         * If it's the first fragment, do the above check for each
@@ -311,7 +513,7 @@ frag6_input(mp, offp, proto)
 
                                /* dequeue the fragment. */
                                frag6_deq(af6);
-                               _FREE(af6, M_FTABLE);
+                               ip6af_free(af6);
 
                                /* adjust pointer. */
                                ip6err = mtod(merr, struct ip6_hdr *);
@@ -323,23 +525,19 @@ frag6_input(mp, offp, proto)
                                ip6err->ip6_src = q6->ip6q_src;
                                ip6err->ip6_dst = q6->ip6q_dst;
 
-                               icmp6_error(merr, ICMP6_PARAM_PROB,
-                                           ICMP6_PARAMPROB_HEADER,
-                                           erroff - sizeof(struct ip6_frag) +
-                                               offsetof(struct ip6_frag, ip6f_offlg));
+                               frag6_save_context(merr,
+                                   erroff - sizeof (struct ip6_frag) +
+                                   offsetof(struct ip6_frag, ip6f_offlg));
+
+                               MBUFQ_ENQUEUE(&diq6, merr);
                        }
                }
        }
 
-       ip6af = (struct ip6asfrag *)_MALLOC(sizeof(struct ip6asfrag), M_FTABLE,
-           M_DONTWAIT);
+       ip6af = ip6af_alloc(M_DONTWAIT);
        if (ip6af == NULL)
                goto dropfrag;
-       bzero(ip6af, sizeof(*ip6af));
-       ip6af->ip6af_head = ip6->ip6_flow;
-       ip6af->ip6af_len = ip6->ip6_plen;
-       ip6af->ip6af_nxt = ip6->ip6_nxt;
-       ip6af->ip6af_hlim = ip6->ip6_hlim;
+
        ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
        ip6af->ip6af_off = fragoff;
        ip6af->ip6af_frglen = frgpartlen;
@@ -351,6 +549,26 @@ frag6_input(mp, offp, proto)
                goto insert;
        }
 
+       /*
+        * Handle ECN by comparing this segment with the first one;
+        * if CE is set, do not lose CE.
+        * drop if CE and not-ECT are mixed for the same packet.
+        */
+       ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
+       ecn0 = q6->ip6q_ecn;
+       if (ecn == IPTOS_ECN_CE) {
+               if (ecn0 == IPTOS_ECN_NOTECT) {
+                       ip6af_free(ip6af);
+                       goto dropfrag;
+               }
+               if (ecn0 != IPTOS_ECN_CE)
+                       q6->ip6q_ecn = IPTOS_ECN_CE;
+       }
+       if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
+               ip6af_free(ip6af);
+               goto dropfrag;
+       }
+
        /*
         * Find a segment which begins after this one does.
         */
@@ -364,6 +582,9 @@ frag6_input(mp, offp, proto)
         * If there is a preceding segment, it may provide some of
         * our data already.  If so, drop the data from the incoming
         * segment.  If it provides all of our data, drop us.
+        *
+        * If some of the data is dropped from the preceding
+        * segment, then it's checksum is invalidated.
         */
        if (af6->ip6af_up != (struct ip6asfrag *)q6) {
                i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
@@ -372,6 +593,7 @@ frag6_input(mp, offp, proto)
                        if (i >= ip6af->ip6af_frglen)
                                goto dropfrag;
                        m_adj(IP6_REASS_MBUF(ip6af), i);
+                       q6->ip6q_csum_flags = 0;
                        ip6af->ip6af_off += i;
                        ip6af->ip6af_frglen -= i;
                }
@@ -388,6 +610,7 @@ frag6_input(mp, offp, proto)
                        af6->ip6af_frglen -= i;
                        af6->ip6af_off += i;
                        m_adj(IP6_REASS_MBUF(af6), i);
+                       q6->ip6q_csum_flags = 0;
                        break;
                }
                af6 = af6->ip6af_down;
@@ -399,28 +622,49 @@ frag6_input(mp, offp, proto)
         * If the incoming framgent overlaps some existing fragments in
         * the reassembly queue, drop it, since it is dangerous to override
         * existing fragments from a security point of view.
+        * We don't know which fragment is the bad guy - here we trust
+        * fragment that came in earlier, with no real reason.
+        *
+        * Note: due to changes after disabling this part, mbuf passed to
+        * m_adj() below now does not meet the requirement.
         */
        if (af6->ip6af_up != (struct ip6asfrag *)q6) {
                i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
                        - ip6af->ip6af_off;
                if (i > 0) {
+#if 0                          /* suppress the noisy log */
                        log(LOG_ERR, "%d bytes of a fragment from %s "
                            "overlaps the previous fragment\n",
                            i, ip6_sprintf(&q6->ip6q_src));
+#endif
+                       ip6af_free(ip6af);
                        goto dropfrag;
                }
        }
        if (af6 != (struct ip6asfrag *)q6) {
                i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
                if (i > 0) {
+#if 0                          /* suppress the noisy log */
                        log(LOG_ERR, "%d bytes of a fragment from %s "
                            "overlaps the succeeding fragment",
                            i, ip6_sprintf(&q6->ip6q_src));
+#endif
+                       ip6af_free(ip6af);
                        goto dropfrag;
                }
        }
 #endif
 
+       /*
+        * If this fragment contains similar checksum offload info
+        * as that of the existing ones, accumulate checksum.  Otherwise,
+        * invalidate checksum offload info for the entire datagram.
+        */
+       if (csum_flags != 0 && csum_flags == q6->ip6q_csum_flags)
+               q6->ip6q_csum += csum;
+       else if (q6->ip6q_csum_flags != 0)
+               q6->ip6q_csum_flags = 0;
+
 insert:
 
        /*
@@ -430,6 +674,8 @@ insert:
         * the most recently active fragmented packet.
         */
        frag6_enq(ip6af, af6->ip6af_up);
+       frag6_nfrags++;
+       q6->ip6q_nfrag++;
 #if 0 /* xxx */
        if (q6 != ip6q.ip6q_next) {
                frag6_remque(q6);
@@ -440,14 +686,18 @@ insert:
        for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
             af6 = af6->ip6af_down) {
                if (af6->ip6af_off != next) {
-                       frag6_doing_reass = 0;
-                       return IPPROTO_DONE;
+                       lck_mtx_unlock(&ip6qlock);
+                       locked = 0;
+                       m = NULL;
+                       goto done;
                }
                next += af6->ip6af_frglen;
        }
        if (af6->ip6af_up->ip6af_mff) {
-               frag6_doing_reass = 0;
-               return IPPROTO_DONE;
+               lck_mtx_unlock(&ip6qlock);
+               locked = 0;
+               m = NULL;
+               goto done;
        }
 
        /*
@@ -464,36 +714,60 @@ insert:
                        t = t->m_next;
                t->m_next = IP6_REASS_MBUF(af6);
                m_adj(t->m_next, af6->ip6af_offset);
-               _FREE(af6, M_FTABLE);
+               ip6af_free(af6);
                af6 = af6dwn;
        }
 
+       /*
+        * Store partial hardware checksum info from the fragment queue;
+        * the receive start offset is set to 40 bytes (see code at the
+        * top of this routine.)
+        */
+       if (q6->ip6q_csum_flags != 0) {
+               csum = q6->ip6q_csum;
+
+               ADDCARRY(csum);
+
+               m->m_pkthdr.csum_rx_val = csum;
+               m->m_pkthdr.csum_rx_start = sizeof (struct ip6_hdr);
+               m->m_pkthdr.csum_flags = q6->ip6q_csum_flags;
+       } else if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
+           (m->m_pkthdr.pkt_flags & PKTF_LOOP)) {
+               /* loopback checksums are always OK */
+               m->m_pkthdr.csum_data = 0xffff;
+               m->m_pkthdr.csum_flags &= ~CSUM_PARTIAL;
+               m->m_pkthdr.csum_flags = CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
+       }
+
        /* adjust offset to point where the original next header starts */
        offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
-       _FREE(ip6af, M_FTABLE);
+       ip6af_free(ip6af);
        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
        ip6->ip6_src = q6->ip6q_src;
        ip6->ip6_dst = q6->ip6q_dst;
+       if (q6->ip6q_ecn == IPTOS_ECN_CE)
+               ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
+
        nxt = q6->ip6q_nxt;
-#if notyet
+#ifdef notyet
        *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
 #endif
 
-       /*
-        * Delete frag6 header with as a few cost as possible.
-        */
-       if (offset < m->m_len) {
+       /* Delete frag6 header */
+       if (m->m_len >= offset + sizeof(struct ip6_frag)) {
+               /* This is the only possible case with !PULLDOWN_TEST */
                ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
-                       offset);
+                   offset);
                m->m_data += sizeof(struct ip6_frag);
                m->m_len -= sizeof(struct ip6_frag);
        } else {
                /* this comes with no copy if the boundary is on cluster */
                if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
                        frag6_remque(q6);
-                       _FREE(q6, M_FTABLE);
                        frag6_nfragpackets--;
+                       frag6_nfrags -= q6->ip6q_nfrag;
+                       ip6q_free(q6);
                        goto dropfrag;
                }
                m_adj(t, sizeof(struct ip6_frag));
@@ -509,34 +783,56 @@ insert:
        }
 
        frag6_remque(q6);
-       _FREE(q6, M_FTABLE);
        frag6_nfragpackets--;
+       frag6_nfrags -= q6->ip6q_nfrag;
+       ip6q_free(q6);
+
+       if (m->m_flags & M_PKTHDR)      /* Isn't it always true? */
+               m_fixhdr(m);
 
-       if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
-               int plen = 0;
-               for (t = m; t; t = t->m_next)
-                       plen += t->m_len;
-               m->m_pkthdr.len = plen;
-       }
-       
        ip6stat.ip6s_reassembled++;
-       in6_ifstat_inc(dstifp, ifs6_reass_ok);
 
        /*
         * Tell launch routine the next header
         */
-
        *mp = m;
        *offp = offset;
 
-       frag6_doing_reass = 0;
-       return nxt;
-
- dropfrag:
-       in6_ifstat_inc(dstifp, ifs6_reass_fail);
+       /* arm the purge timer if not already and if there's work to do */
+       frag6_sched_timeout();
+       lck_mtx_unlock(&ip6qlock);
+       in6_ifstat_inc(dstifp, ifs6_reass_ok);
+       frag6_icmp6_paramprob_error(&diq6);
+       VERIFY(MBUFQ_EMPTY(&diq6));
+       return (nxt);
+
+done:
+       VERIFY(m == NULL);
+       if (!locked) {
+               if (frag6_nfragpackets == 0) {
+                       frag6_icmp6_paramprob_error(&diq6);
+                       VERIFY(MBUFQ_EMPTY(&diq6));
+                       return (IPPROTO_DONE);
+               }
+               lck_mtx_lock(&ip6qlock);
+       }
+       /* arm the purge timer if not already and if there's work to do */
+       frag6_sched_timeout();
+       lck_mtx_unlock(&ip6qlock);
+       frag6_icmp6_paramprob_error(&diq6);
+       VERIFY(MBUFQ_EMPTY(&diq6));
+       return (IPPROTO_DONE);
+
+dropfrag:
        ip6stat.ip6s_fragdropped++;
+       /* arm the purge timer if not already and if there's work to do */
+       frag6_sched_timeout();
+       lck_mtx_unlock(&ip6qlock);
+       in6_ifstat_inc(dstifp, ifs6_reass_fail);
        m_freem(m);
-       return IPPROTO_DONE;
+       frag6_icmp6_paramprob_error(&diq6);
+       VERIFY(MBUFQ_EMPTY(&diq6));
+       return (IPPROTO_DONE);
 }
 
 /*
@@ -544,11 +840,12 @@ insert:
  * associated datagrams.
  */
 void
-frag6_freef(q6)
-       struct ip6q *q6;
+frag6_freef(struct ip6q *q6, struct fq6_head *dfq6, struct fq6_head *diq6)
 {
        struct ip6asfrag *af6, *down6;
 
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+
        for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
             af6 = down6) {
                struct mbuf *m = IP6_REASS_MBUF(af6);
@@ -566,20 +863,21 @@ frag6_freef(q6)
                        /* adjust pointer */
                        ip6 = mtod(m, struct ip6_hdr *);
 
-                       /* restoure source and destination addresses */
+                       /* restore source and destination addresses */
                        ip6->ip6_src = q6->ip6q_src;
                        ip6->ip6_dst = q6->ip6q_dst;
 
-                       icmp6_error(m, ICMP6_TIME_EXCEEDED,
-                                   ICMP6_TIME_EXCEED_REASSEMBLY, 0);
-               } else
-                       m_freem(m);
-               _FREE(af6, M_FTABLE);
+                       MBUFQ_ENQUEUE(diq6, m);
+               } else {
+                       MBUFQ_ENQUEUE(dfq6, m);
+               }
+               ip6af_free(af6);
 
        }
        frag6_remque(q6);
-       _FREE(q6, M_FTABLE);
        frag6_nfragpackets--;
+       frag6_nfrags -= q6->ip6q_nfrag;
+       ip6q_free(q6);
 }
 
 /*
@@ -587,9 +885,10 @@ frag6_freef(q6)
  * Like insque, but pointers in middle of structure.
  */
 void
-frag6_enq(af6, up6)
-       struct ip6asfrag *af6, *up6;
+frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
 {
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+
        af6->ip6af_up = up6;
        af6->ip6af_down = up6->ip6af_down;
        up6->ip6af_down->ip6af_up = af6;
@@ -600,17 +899,19 @@ frag6_enq(af6, up6)
  * To frag6_enq as remque is to insque.
  */
 void
-frag6_deq(af6)
-       struct ip6asfrag *af6;
+frag6_deq(struct ip6asfrag *af6)
 {
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+
        af6->ip6af_up->ip6af_down = af6->ip6af_down;
        af6->ip6af_down->ip6af_up = af6->ip6af_up;
 }
 
 void
-frag6_insque(new, old)
-       struct ip6q *new, *old;
+frag6_insque(struct ip6q *new, struct ip6q *old)
 {
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+
        new->ip6q_prev = old;
        new->ip6q_next = old->ip6q_next;
        old->ip6q_next->ip6q_prev= new;
@@ -618,33 +919,37 @@ frag6_insque(new, old)
 }
 
 void
-frag6_remque(p6)
-       struct ip6q *p6;
+frag6_remque(struct ip6q *p6)
 {
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+
        p6->ip6q_prev->ip6q_next = p6->ip6q_next;
        p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
 }
 
 /*
- * IP timer processing;
+ * IPv6 reassembling timer processing;
  * if a timer expires on a reassembly
  * queue, discard it.
  */
-void
-frag6_slowtimo()
+static void
+frag6_timeout(void *arg)
 {
+#pragma unused(arg)
+       struct fq6_head dfq6, diq6;
        struct ip6q *q6;
-       int s;
-#ifdef __NetBSD__
-       s = splsoftnet();
-#else
-       s = splnet();
-#endif
-#if 0
-       extern struct   route_in6 ip6_forward_rt;
-#endif
 
-       frag6_doing_reass = 1;
+       MBUFQ_INIT(&dfq6);      /* for deferred frees */
+       MBUFQ_INIT(&diq6);      /* for deferred ICMP time exceeded errors */
+
+       /*
+        * Update coarse-grained networking timestamp (in sec.); the idea
+        * is to piggy-back on the timeout callout to update the counter
+        * returnable via net_uptime().
+        */
+       net_update_uptime();
+
+       lck_mtx_lock(&ip6qlock);
        q6 = ip6q.ip6q_next;
        if (q6)
                while (q6 != &ip6q) {
@@ -653,7 +958,7 @@ frag6_slowtimo()
                        if (q6->ip6q_prev->ip6q_ttl == 0) {
                                ip6stat.ip6s_fragtimeout++;
                                /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
-                               frag6_freef(q6->ip6q_prev);
+                               frag6_freef(q6->ip6q_prev, &dfq6, &diq6);
                        }
                }
        /*
@@ -661,43 +966,208 @@ frag6_slowtimo()
         * (due to the limit being lowered), drain off
         * enough to get down to the new limit.
         */
-       while (frag6_nfragpackets > (u_int)ip6_maxfragpackets) {
-               ip6stat.ip6s_fragoverflow++;
-               /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
-               frag6_freef(ip6q.ip6q_prev);
+       if (ip6_maxfragpackets >= 0) {
+               while (frag6_nfragpackets > (unsigned)ip6_maxfragpackets &&
+                   ip6q.ip6q_prev) {
+                       ip6stat.ip6s_fragoverflow++;
+                       /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
+                       frag6_freef(ip6q.ip6q_prev, &dfq6, &diq6);
+               }
        }
-       frag6_doing_reass = 0;
+       /* re-arm the purge timer if there's work to do */
+       frag6_timeout_run = 0;
+       frag6_sched_timeout();
+       lck_mtx_unlock(&ip6qlock);
 
-#if 0
-       /*
-        * Routing changes might produce a better route than we last used;
-        * make sure we notice eventually, even if forwarding only for one
-        * destination and the cache is never replaced.
-        */
-       if (ip6_forward_rt.ro_rt) {
-               RTFREE(ip6_forward_rt.ro_rt);
-               ip6_forward_rt.ro_rt = 0;
-       }
-       if (ipsrcchk_rt.ro_rt) {
-               RTFREE(ipsrcchk_rt.ro_rt);
-               ipsrcchk_rt.ro_rt = 0;
-       }
-#endif
+       /* free fragments that need to be freed */
+       if (!MBUFQ_EMPTY(&dfq6))
+               MBUFQ_DRAIN(&dfq6);
+
+       frag6_icmp6_timeex_error(&diq6);
+
+       VERIFY(MBUFQ_EMPTY(&dfq6));
+       VERIFY(MBUFQ_EMPTY(&diq6));
+}
+
+static void
+frag6_sched_timeout(void)
+{
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
 
-       splx(s);
+       if (!frag6_timeout_run && frag6_nfragpackets > 0) {
+               frag6_timeout_run = 1;
+               timeout(frag6_timeout, NULL, hz);
+       }
 }
 
 /*
  * Drain off all datagram fragments.
  */
 void
-frag6_drain()
+frag6_drain(void)
 {
-       if (frag6_doing_reass)
-               return;
+       struct fq6_head dfq6, diq6;
+
+       MBUFQ_INIT(&dfq6);      /* for deferred frees */
+       MBUFQ_INIT(&diq6);      /* for deferred ICMP time exceeded errors */
+
+       lck_mtx_lock(&ip6qlock);
        while (ip6q.ip6q_next != &ip6q) {
                ip6stat.ip6s_fragdropped++;
                /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
-               frag6_freef(ip6q.ip6q_next);
+               frag6_freef(ip6q.ip6q_next, &dfq6, &diq6);
+       }
+       lck_mtx_unlock(&ip6qlock);
+
+       /* free fragments that need to be freed */
+       if (!MBUFQ_EMPTY(&dfq6))
+               MBUFQ_DRAIN(&dfq6);
+
+       frag6_icmp6_timeex_error(&diq6);
+
+       VERIFY(MBUFQ_EMPTY(&dfq6));
+       VERIFY(MBUFQ_EMPTY(&diq6));
+}
+
+static struct ip6q *
+ip6q_alloc(int how)
+{
+       struct mbuf *t;
+       struct ip6q *q6;
+
+       /*
+        * See comments in ip6q_updateparams().  Keep the count separate
+        * from frag6_nfragpackets since the latter represents the elements
+        * already in the reassembly queues.
+        */
+       if (ip6q_limit > 0 && ip6q_count > ip6q_limit)
+               return (NULL);
+
+       t = m_get(how, MT_FTABLE);
+       if (t != NULL) {
+               atomic_add_32(&ip6q_count, 1);
+               q6 = mtod(t, struct ip6q *);
+               bzero(q6, sizeof (*q6));
+       } else {
+               q6 = NULL;
+       }
+       return (q6);
+}
+
+static void
+ip6q_free(struct ip6q *q6)
+{
+       (void) m_free(dtom(q6));
+       atomic_add_32(&ip6q_count, -1);
+}
+
+static struct ip6asfrag *
+ip6af_alloc(int how)
+{
+       struct mbuf *t;
+       struct ip6asfrag *af6;
+
+       /*
+        * See comments in ip6q_updateparams().  Keep the count separate
+        * from frag6_nfrags since the latter represents the elements
+        * already in the reassembly queues.
+        */
+       if (ip6af_limit > 0 && ip6af_count > ip6af_limit)
+               return (NULL);
+
+       t = m_get(how, MT_FTABLE);
+       if (t != NULL) {
+               atomic_add_32(&ip6af_count, 1);
+               af6 = mtod(t, struct ip6asfrag *);
+               bzero(af6, sizeof (*af6));
+       } else {
+               af6 = NULL;
+       }
+       return (af6);
+}
+
+static void
+ip6af_free(struct ip6asfrag *af6)
+{
+       (void) m_free(dtom(af6));
+       atomic_add_32(&ip6af_count, -1);
+}
+
+static void
+ip6q_updateparams(void)
+{
+       lck_mtx_assert(&ip6qlock, LCK_MTX_ASSERT_OWNED);
+       /*
+        * -1 for unlimited allocation.
+        */
+       if (ip6_maxfragpackets < 0)
+               ip6q_limit = 0;
+       if (ip6_maxfrags < 0)
+               ip6af_limit = 0;
+       /*
+        * Positive number for specific bound.
+        */
+       if (ip6_maxfragpackets > 0)
+               ip6q_limit = ip6_maxfragpackets;
+       if (ip6_maxfrags > 0)
+               ip6af_limit = ip6_maxfrags;
+       /*
+        * Zero specifies no further fragment queue allocation -- set the
+        * bound very low, but rely on implementation elsewhere to actually
+        * prevent allocation and reclaim current queues.
+        */
+       if (ip6_maxfragpackets == 0)
+               ip6q_limit = 1;
+       if (ip6_maxfrags == 0)
+               ip6af_limit = 1;
+       /*
+        * Arm the purge timer if not already and if there's work to do
+        */
+       frag6_sched_timeout();
+}
+
+static int
+sysctl_maxfragpackets SYSCTL_HANDLER_ARGS
+{
+#pragma unused(arg1, arg2)
+       int error, i;
+
+       lck_mtx_lock(&ip6qlock);
+       i = ip6_maxfragpackets;
+       error = sysctl_handle_int(oidp, &i, 0, req);
+       if (error || req->newptr == USER_ADDR_NULL)
+               goto done;
+       /* impose bounds */
+       if (i < -1 || i > (nmbclusters / 4)) {
+               error = EINVAL;
+               goto done;
+       }
+       ip6_maxfragpackets = i;
+       ip6q_updateparams();
+done:
+       lck_mtx_unlock(&ip6qlock);
+       return (error);
+}
+
+static int
+sysctl_maxfrags SYSCTL_HANDLER_ARGS
+{
+#pragma unused(arg1, arg2)
+       int error, i;
+
+       lck_mtx_lock(&ip6qlock);
+       i = ip6_maxfrags;
+       error = sysctl_handle_int(oidp, &i, 0, req);
+       if (error || req->newptr == USER_ADDR_NULL)
+               goto done;
+       /* impose bounds */
+       if (i < -1 || i > (nmbclusters / 4)) {
+               error = EINVAL;
+               goto done;
        }
+       ip6_maxfrags= i;
+       ip6q_updateparams();    /* see if we need to arm timer */
+done:
+       lck_mtx_unlock(&ip6qlock);
+       return (error);
 }