The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/frag6.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/6.4/sys/netinet6/frag6.c 182649 2008-09-01 22:57:56Z obrien $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/malloc.h>
   38 #include <sys/mbuf.h>
   39 #include <sys/domain.h>
   40 #include <sys/protosw.h>
   41 #include <sys/socket.h>
   42 #include <sys/errno.h>
   43 #include <sys/time.h>
   44 #include <sys/kernel.h>
   45 #include <sys/syslog.h>
   46 
   47 #include <net/if.h>
   48 #include <net/route.h>
   49 
   50 #include <netinet/in.h>
   51 #include <netinet/in_var.h>
   52 #include <netinet/ip6.h>
   53 #include <netinet6/ip6_var.h>
   54 #include <netinet/icmp6.h>
   55 #include <netinet/in_systm.h>   /* for ECN definitions */
   56 #include <netinet/ip.h>         /* for ECN definitions */
   57 
   58 #include <net/net_osdep.h>
   59 
   60 /*
   61  * Define it to get a correct behavior on per-interface statistics.
   62  * You will need to perform an extra routing table lookup, per fragment,
   63  * to do it.  This may, or may not be, a performance hit.
   64  */
   65 #define IN6_IFSTAT_STRICT
   66 
   67 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
   68 static void frag6_deq(struct ip6asfrag *);
   69 static void frag6_insque(struct ip6q *, struct ip6q *);
   70 static void frag6_remque(struct ip6q *);
   71 static void frag6_freef(struct ip6q *);
   72 
   73 static struct mtx ip6qlock;
   74 /*
   75  * These fields all protected by ip6qlock.
   76  */
   77 static u_int frag6_nfragpackets;
   78 static u_int frag6_nfrags;
   79 static struct   ip6q ip6q;      /* ip6 reassemble queue */
   80 
   81 #define IP6Q_LOCK_INIT()        mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
   82 #define IP6Q_LOCK()             mtx_lock(&ip6qlock)
   83 #define IP6Q_TRYLOCK()          mtx_trylock(&ip6qlock)
   84 #define IP6Q_LOCK_ASSERT()      mtx_assert(&ip6qlock, MA_OWNED)
   85 #define IP6Q_UNLOCK()           mtx_unlock(&ip6qlock)
   86 
   87 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
   88 
   89 /*
   90  * Initialise reassembly queue and fragment identifier.
   91  */
   92 static void
   93 frag6_change(void *tag)
   94 {
   95 
   96         ip6_maxfragpackets = nmbclusters / 4;
   97         ip6_maxfrags = nmbclusters / 4;
   98 }
   99 
  100 void
  101 frag6_init()
  102 {
  103 
  104         ip6_maxfragpackets = nmbclusters / 4;
  105         ip6_maxfrags = nmbclusters / 4;
  106         EVENTHANDLER_REGISTER(nmbclusters_change,
  107             frag6_change, NULL, EVENTHANDLER_PRI_ANY);
  108 
  109         IP6Q_LOCK_INIT();
  110 
  111         ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
  112 }
  113 
  114 /*
  115  * In RFC2460, fragment and reassembly rule do not agree with each other,
  116  * in terms of next header field handling in fragment header.
  117  * While the sender will use the same value for all of the fragmented packets,
  118  * receiver is suggested not to check the consistency.
  119  *
  120  * fragment rule (p20):
  121  *      (2) A Fragment header containing:
  122  *      The Next Header value that identifies the first header of
  123  *      the Fragmentable Part of the original packet.
  124  *              -> next header field is same for all fragments
  125  *
  126  * reassembly rule (p21):
  127  *      The Next Header field of the last header of the Unfragmentable
  128  *      Part is obtained from the Next Header field of the first
  129  *      fragment's Fragment header.
  130  *              -> should grab it from the first fragment only
  131  *
  132  * The following note also contradicts with fragment rule - noone is going to
  133  * send different fragment with different next header field.
  134  *
  135  * additional note (p22):
  136  *      The Next Header values in the Fragment headers of different
  137  *      fragments of the same original packet may differ.  Only the value
  138  *      from the Offset zero fragment packet is used for reassembly.
  139  *              -> should grab it from the first fragment only
  140  *
  141  * There is no explicit reason given in the RFC.  Historical reason maybe?
  142  */
  143 /*
  144  * Fragment input
  145  */
  146 int
  147 frag6_input(mp, offp, proto)
  148         struct mbuf **mp;
  149         int *offp, proto;
  150 {
  151         struct mbuf *m = *mp, *t;
  152         struct ip6_hdr *ip6;
  153         struct ip6_frag *ip6f;
  154         struct ip6q *q6;
  155         struct ip6asfrag *af6, *ip6af, *af6dwn;
  156 #ifdef IN6_IFSTAT_STRICT
  157         struct in6_ifaddr *ia;
  158 #endif
  159         int offset = *offp, nxt, i, next;
  160         int first_frag = 0;
  161         int fragoff, frgpartlen;        /* must be larger than u_int16_t */
  162         struct ifnet *dstifp;
  163         u_int8_t ecn, ecn0;
  164 
  165         ip6 = mtod(m, struct ip6_hdr *);
  166 #ifndef PULLDOWN_TEST
  167         IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
  168         ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
  169 #else
  170         IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
  171         if (ip6f == NULL)
  172                 return (IPPROTO_DONE);
  173 #endif
  174 
  175         dstifp = NULL;
  176 #ifdef IN6_IFSTAT_STRICT
  177         /* find the destination interface of the packet. */
  178         if ((ia = ip6_getdstifaddr(m)) != NULL)
  179                 dstifp = ia->ia_ifp;
  180 #else
  181         /* we are violating the spec, this is not the destination interface */
  182         if ((m->m_flags & M_PKTHDR) != 0)
  183                 dstifp = m->m_pkthdr.rcvif;
  184 #endif
  185 
  186         /* jumbo payload can't contain a fragment header */
  187         if (ip6->ip6_plen == 0) {
  188                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
  189                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  190                 return IPPROTO_DONE;
  191         }
  192 
  193         /*
  194          * check whether fragment packet's fragment length is
  195          * multiple of 8 octets.
  196          * sizeof(struct ip6_frag) == 8
  197          * sizeof(struct ip6_hdr) = 40
  198          */
  199         if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
  200             (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
  201                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  202                     offsetof(struct ip6_hdr, ip6_plen));
  203                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  204                 return IPPROTO_DONE;
  205         }
  206 
  207         ip6stat.ip6s_fragments++;
  208         in6_ifstat_inc(dstifp, ifs6_reass_reqd);
  209 
  210         /* offset now points to data portion */
  211         offset += sizeof(struct ip6_frag);
  212 
  213         IP6Q_LOCK();
  214 
  215         /*
  216          * Enforce upper bound on number of fragments.
  217          * If maxfrag is 0, never accept fragments.
  218          * If maxfrag is -1, accept all fragments without limitation.
  219          */
  220         if (ip6_maxfrags < 0)
  221                 ;
  222         else if (frag6_nfrags >= (u_int)ip6_maxfrags)
  223                 goto dropfrag;
  224 
  225         for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
  226                 if (ip6f->ip6f_ident == q6->ip6q_ident &&
  227                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
  228                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
  229                         break;
  230 
  231         if (q6 == &ip6q) {
  232                 /*
  233                  * the first fragment to arrive, create a reassembly queue.
  234                  */
  235                 first_frag = 1;
  236 
  237                 /*
  238                  * Enforce upper bound on number of fragmented packets
  239                  * for which we attempt reassembly;
  240                  * If maxfragpackets is 0, never accept fragments.
  241                  * If maxfragpackets is -1, accept all fragments without
  242                  * limitation.
  243                  */
  244                 if (ip6_maxfragpackets < 0)
  245                         ;
  246                 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
  247                         goto dropfrag;
  248                 frag6_nfragpackets++;
  249                 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
  250                     M_NOWAIT);
  251                 if (q6 == NULL)
  252                         goto dropfrag;
  253                 bzero(q6, sizeof(*q6));
  254 
  255                 frag6_insque(q6, &ip6q);
  256 
  257                 /* ip6q_nxt will be filled afterwards, from 1st fragment */
  258                 q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
  259 #ifdef notyet
  260                 q6->ip6q_nxtp   = (u_char *)nxtp;
  261 #endif
  262                 q6->ip6q_ident  = ip6f->ip6f_ident;
  263                 q6->ip6q_ttl    = IPV6_FRAGTTL;
  264                 q6->ip6q_src    = ip6->ip6_src;
  265                 q6->ip6q_dst    = ip6->ip6_dst;
  266                 q6->ip6q_ecn    =
  267                     (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  268                 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
  269 
  270                 q6->ip6q_nfrag = 0;
  271         }
  272 
  273         /*
  274          * If it's the 1st fragment, record the length of the
  275          * unfragmentable part and the next header of the fragment header.
  276          */
  277         fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
  278         if (fragoff == 0) {
  279                 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
  280                     sizeof(struct ip6_frag);
  281                 q6->ip6q_nxt = ip6f->ip6f_nxt;
  282         }
  283 
  284         /*
  285          * Check that the reassembled packet would not exceed 65535 bytes
  286          * in size.
  287          * If it would exceed, discard the fragment and return an ICMP error.
  288          */
  289         frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
  290         if (q6->ip6q_unfrglen >= 0) {
  291                 /* The 1st fragment has already arrived. */
  292                 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
  293                         icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  294                             offset - sizeof(struct ip6_frag) +
  295                             offsetof(struct ip6_frag, ip6f_offlg));
  296                         IP6Q_UNLOCK();
  297                         return (IPPROTO_DONE);
  298                 }
  299         } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
  300                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  301                     offset - sizeof(struct ip6_frag) +
  302                     offsetof(struct ip6_frag, ip6f_offlg));
  303                 IP6Q_UNLOCK();
  304                 return (IPPROTO_DONE);
  305         }
  306         /*
  307          * If it's the first fragment, do the above check for each
  308          * fragment already stored in the reassembly queue.
  309          */
  310         if (fragoff == 0) {
  311                 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  312                      af6 = af6dwn) {
  313                         af6dwn = af6->ip6af_down;
  314 
  315                         if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
  316                             IPV6_MAXPACKET) {
  317                                 struct mbuf *merr = IP6_REASS_MBUF(af6);
  318                                 struct ip6_hdr *ip6err;
  319                                 int erroff = af6->ip6af_offset;
  320 
  321                                 /* dequeue the fragment. */
  322                                 frag6_deq(af6);
  323                                 free(af6, M_FTABLE);
  324 
  325                                 /* adjust pointer. */
  326                                 ip6err = mtod(merr, struct ip6_hdr *);
  327 
  328                                 /*
  329                                  * Restore source and destination addresses
  330                                  * in the erroneous IPv6 header.
  331                                  */
  332                                 ip6err->ip6_src = q6->ip6q_src;
  333                                 ip6err->ip6_dst = q6->ip6q_dst;
  334 
  335                                 icmp6_error(merr, ICMP6_PARAM_PROB,
  336                                     ICMP6_PARAMPROB_HEADER,
  337                                     erroff - sizeof(struct ip6_frag) +
  338                                     offsetof(struct ip6_frag, ip6f_offlg));
  339                         }
  340                 }
  341         }
  342 
  343         ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
  344             M_NOWAIT);
  345         if (ip6af == NULL)
  346                 goto dropfrag;
  347         bzero(ip6af, sizeof(*ip6af));
  348         ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
  349         ip6af->ip6af_off = fragoff;
  350         ip6af->ip6af_frglen = frgpartlen;
  351         ip6af->ip6af_offset = offset;
  352         IP6_REASS_MBUF(ip6af) = m;
  353 
  354         if (first_frag) {
  355                 af6 = (struct ip6asfrag *)q6;
  356                 goto insert;
  357         }
  358 
  359         /*
  360          * Handle ECN by comparing this segment with the first one;
  361          * if CE is set, do not lose CE.
  362          * drop if CE and not-ECT are mixed for the same packet.
  363          */
  364         ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  365         ecn0 = q6->ip6q_ecn;
  366         if (ecn == IPTOS_ECN_CE) {
  367                 if (ecn0 == IPTOS_ECN_NOTECT) {
  368                         free(ip6af, M_FTABLE);
  369                         goto dropfrag;
  370                 }
  371                 if (ecn0 != IPTOS_ECN_CE)
  372                         q6->ip6q_ecn = IPTOS_ECN_CE;
  373         }
  374         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
  375                 free(ip6af, M_FTABLE);
  376                 goto dropfrag;
  377         }
  378 
  379         /*
  380          * Find a segment which begins after this one does.
  381          */
  382         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  383              af6 = af6->ip6af_down)
  384                 if (af6->ip6af_off > ip6af->ip6af_off)
  385                         break;
  386 
  387 #if 0
  388         /*
  389          * If there is a preceding segment, it may provide some of
  390          * our data already.  If so, drop the data from the incoming
  391          * segment.  If it provides all of our data, drop us.
  392          */
  393         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  394                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  395                         - ip6af->ip6af_off;
  396                 if (i > 0) {
  397                         if (i >= ip6af->ip6af_frglen)
  398                                 goto dropfrag;
  399                         m_adj(IP6_REASS_MBUF(ip6af), i);
  400                         ip6af->ip6af_off += i;
  401                         ip6af->ip6af_frglen -= i;
  402                 }
  403         }
  404 
  405         /*
  406          * While we overlap succeeding segments trim them or,
  407          * if they are completely covered, dequeue them.
  408          */
  409         while (af6 != (struct ip6asfrag *)q6 &&
  410                ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
  411                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  412                 if (i < af6->ip6af_frglen) {
  413                         af6->ip6af_frglen -= i;
  414                         af6->ip6af_off += i;
  415                         m_adj(IP6_REASS_MBUF(af6), i);
  416                         break;
  417                 }
  418                 af6 = af6->ip6af_down;
  419                 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
  420                 frag6_deq(af6->ip6af_up);
  421         }
  422 #else
  423         /*
  424          * If the incoming framgent overlaps some existing fragments in
  425          * the reassembly queue, drop it, since it is dangerous to override
  426          * existing fragments from a security point of view.
  427          * We don't know which fragment is the bad guy - here we trust
  428          * fragment that came in earlier, with no real reason.
  429          *
  430          * Note: due to changes after disabling this part, mbuf passed to
  431          * m_adj() below now does not meet the requirement.
  432          */
  433         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  434                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  435                         - ip6af->ip6af_off;
  436                 if (i > 0) {
  437 #if 0                           /* suppress the noisy log */
  438                         log(LOG_ERR, "%d bytes of a fragment from %s "
  439                             "overlaps the previous fragment\n",
  440                             i, ip6_sprintf(&q6->ip6q_src));
  441 #endif
  442                         free(ip6af, M_FTABLE);
  443                         goto dropfrag;
  444                 }
  445         }
  446         if (af6 != (struct ip6asfrag *)q6) {
  447                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  448                 if (i > 0) {
  449 #if 0                           /* suppress the noisy log */
  450                         log(LOG_ERR, "%d bytes of a fragment from %s "
  451                             "overlaps the succeeding fragment",
  452                             i, ip6_sprintf(&q6->ip6q_src));
  453 #endif
  454                         free(ip6af, M_FTABLE);
  455                         goto dropfrag;
  456                 }
  457         }
  458 #endif
  459 
  460 insert:
  461 
  462         /*
  463          * Stick new segment in its place;
  464          * check for complete reassembly.
  465          * Move to front of packet queue, as we are
  466          * the most recently active fragmented packet.
  467          */
  468         frag6_enq(ip6af, af6->ip6af_up);
  469         frag6_nfrags++;
  470         q6->ip6q_nfrag++;
  471 #if 0 /* xxx */
  472         if (q6 != ip6q.ip6q_next) {
  473                 frag6_remque(q6);
  474                 frag6_insque(q6, &ip6q);
  475         }
  476 #endif
  477         next = 0;
  478         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  479              af6 = af6->ip6af_down) {
  480                 if (af6->ip6af_off != next) {
  481                         IP6Q_UNLOCK();
  482                         return IPPROTO_DONE;
  483                 }
  484                 next += af6->ip6af_frglen;
  485         }
  486         if (af6->ip6af_up->ip6af_mff) {
  487                 IP6Q_UNLOCK();
  488                 return IPPROTO_DONE;
  489         }
  490 
  491         /*
  492          * Reassembly is complete; concatenate fragments.
  493          */
  494         ip6af = q6->ip6q_down;
  495         t = m = IP6_REASS_MBUF(ip6af);
  496         af6 = ip6af->ip6af_down;
  497         frag6_deq(ip6af);
  498         while (af6 != (struct ip6asfrag *)q6) {
  499                 af6dwn = af6->ip6af_down;
  500                 frag6_deq(af6);
  501                 while (t->m_next)
  502                         t = t->m_next;
  503                 t->m_next = IP6_REASS_MBUF(af6);
  504                 m_adj(t->m_next, af6->ip6af_offset);
  505                 free(af6, M_FTABLE);
  506                 af6 = af6dwn;
  507         }
  508 
  509         /* adjust offset to point where the original next header starts */
  510         offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
  511         free(ip6af, M_FTABLE);
  512         ip6 = mtod(m, struct ip6_hdr *);
  513         ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
  514         if (q6->ip6q_ecn == IPTOS_ECN_CE)
  515                 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
  516         nxt = q6->ip6q_nxt;
  517 #ifdef notyet
  518         *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
  519 #endif
  520 
  521         /* Delete frag6 header */
  522         if (m->m_len >= offset + sizeof(struct ip6_frag)) {
  523                 /* This is the only possible case with !PULLDOWN_TEST */
  524                 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
  525                     offset);
  526                 m->m_data += sizeof(struct ip6_frag);
  527                 m->m_len -= sizeof(struct ip6_frag);
  528         } else {
  529                 /* this comes with no copy if the boundary is on cluster */
  530                 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
  531                         frag6_remque(q6);
  532                         frag6_nfrags -= q6->ip6q_nfrag;
  533                         free(q6, M_FTABLE);
  534                         frag6_nfragpackets--;
  535                         goto dropfrag;
  536                 }
  537                 m_adj(t, sizeof(struct ip6_frag));
  538                 m_cat(m, t);
  539         }
  540 
  541         /*
  542          * Store NXT to the original.
  543          */
  544         {
  545                 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
  546                 *prvnxtp = nxt;
  547         }
  548 
  549         frag6_remque(q6);
  550         frag6_nfrags -= q6->ip6q_nfrag;
  551         free(q6, M_FTABLE);
  552         frag6_nfragpackets--;
  553 
  554         if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
  555                 int plen = 0;
  556                 for (t = m; t; t = t->m_next)
  557                         plen += t->m_len;
  558                 m->m_pkthdr.len = plen;
  559         }
  560 
  561         ip6stat.ip6s_reassembled++;
  562         in6_ifstat_inc(dstifp, ifs6_reass_ok);
  563 
  564         /*
  565          * Tell launch routine the next header
  566          */
  567 
  568         *mp = m;
  569         *offp = offset;
  570 
  571         IP6Q_UNLOCK();
  572         return nxt;
  573 
  574  dropfrag:
  575         IP6Q_UNLOCK();
  576         in6_ifstat_inc(dstifp, ifs6_reass_fail);
  577         ip6stat.ip6s_fragdropped++;
  578         m_freem(m);
  579         return IPPROTO_DONE;
  580 }
  581 
  582 /*
  583  * Free a fragment reassembly header and all
  584  * associated datagrams.
  585  */
  586 void
  587 frag6_freef(q6)
  588         struct ip6q *q6;
  589 {
  590         struct ip6asfrag *af6, *down6;
  591 
  592         IP6Q_LOCK_ASSERT();
  593 
  594         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  595              af6 = down6) {
  596                 struct mbuf *m = IP6_REASS_MBUF(af6);
  597 
  598                 down6 = af6->ip6af_down;
  599                 frag6_deq(af6);
  600 
  601                 /*
  602                  * Return ICMP time exceeded error for the 1st fragment.
  603                  * Just free other fragments.
  604                  */
  605                 if (af6->ip6af_off == 0) {
  606                         struct ip6_hdr *ip6;
  607 
  608                         /* adjust pointer */
  609                         ip6 = mtod(m, struct ip6_hdr *);
  610 
  611                         /* restore source and destination addresses */
  612                         ip6->ip6_src = q6->ip6q_src;
  613                         ip6->ip6_dst = q6->ip6q_dst;
  614 
  615                         icmp6_error(m, ICMP6_TIME_EXCEEDED,
  616                                     ICMP6_TIME_EXCEED_REASSEMBLY, 0);
  617                 } else
  618                         m_freem(m);
  619                 free(af6, M_FTABLE);
  620         }
  621         frag6_remque(q6);
  622         frag6_nfrags -= q6->ip6q_nfrag;
  623         free(q6, M_FTABLE);
  624         frag6_nfragpackets--;
  625 }
  626 
  627 /*
  628  * Put an ip fragment on a reassembly chain.
  629  * Like insque, but pointers in middle of structure.
  630  */
  631 void
  632 frag6_enq(af6, up6)
  633         struct ip6asfrag *af6, *up6;
  634 {
  635 
  636         IP6Q_LOCK_ASSERT();
  637 
  638         af6->ip6af_up = up6;
  639         af6->ip6af_down = up6->ip6af_down;
  640         up6->ip6af_down->ip6af_up = af6;
  641         up6->ip6af_down = af6;
  642 }
  643 
  644 /*
  645  * To frag6_enq as remque is to insque.
  646  */
  647 void
  648 frag6_deq(af6)
  649         struct ip6asfrag *af6;
  650 {
  651 
  652         IP6Q_LOCK_ASSERT();
  653 
  654         af6->ip6af_up->ip6af_down = af6->ip6af_down;
  655         af6->ip6af_down->ip6af_up = af6->ip6af_up;
  656 }
  657 
  658 void
  659 frag6_insque(new, old)
  660         struct ip6q *new, *old;
  661 {
  662 
  663         IP6Q_LOCK_ASSERT();
  664 
  665         new->ip6q_prev = old;
  666         new->ip6q_next = old->ip6q_next;
  667         old->ip6q_next->ip6q_prev= new;
  668         old->ip6q_next = new;
  669 }
  670 
  671 void
  672 frag6_remque(p6)
  673         struct ip6q *p6;
  674 {
  675 
  676         IP6Q_LOCK_ASSERT();
  677 
  678         p6->ip6q_prev->ip6q_next = p6->ip6q_next;
  679         p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
  680 }
  681 
  682 /*
  683  * IPv6 reassembling timer processing;
  684  * if a timer expires on a reassembly
  685  * queue, discard it.
  686  */
  687 void
  688 frag6_slowtimo()
  689 {
  690         struct ip6q *q6;
  691         int s = splnet();
  692 
  693         IP6Q_LOCK();
  694         q6 = ip6q.ip6q_next;
  695         if (q6)
  696                 while (q6 != &ip6q) {
  697                         --q6->ip6q_ttl;
  698                         q6 = q6->ip6q_next;
  699                         if (q6->ip6q_prev->ip6q_ttl == 0) {
  700                                 ip6stat.ip6s_fragtimeout++;
  701                                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  702                                 frag6_freef(q6->ip6q_prev);
  703                         }
  704                 }
  705         /*
  706          * If we are over the maximum number of fragments
  707          * (due to the limit being lowered), drain off
  708          * enough to get down to the new limit.
  709          */
  710         while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
  711             ip6q.ip6q_prev) {
  712                 ip6stat.ip6s_fragoverflow++;
  713                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  714                 frag6_freef(ip6q.ip6q_prev);
  715         }
  716         IP6Q_UNLOCK();
  717 
  718 #if 0
  719         /*
  720          * Routing changes might produce a better route than we last used;
  721          * make sure we notice eventually, even if forwarding only for one
  722          * destination and the cache is never replaced.
  723          */
  724         if (ip6_forward_rt.ro_rt) {
  725                 RTFREE(ip6_forward_rt.ro_rt);
  726                 ip6_forward_rt.ro_rt = 0;
  727         }
  728         if (ipsrcchk_rt.ro_rt) {
  729                 RTFREE(ipsrcchk_rt.ro_rt);
  730                 ipsrcchk_rt.ro_rt = 0;
  731         }
  732 #endif
  733 
  734         splx(s);
  735 }
  736 
  737 /*
  738  * Drain off all datagram fragments.
  739  */
  740 void
  741 frag6_drain()
  742 {
  743 
  744         if (IP6Q_TRYLOCK() == 0)
  745                 return;
  746         while (ip6q.ip6q_next != &ip6q) {
  747                 ip6stat.ip6s_fragdropped++;
  748                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  749                 frag6_freef(ip6q.ip6q_next);
  750         }
  751         IP6Q_UNLOCK();
  752 }

Cache object: 702be6d9e3b9e5b32e8f0ed5ecae030c


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