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: stable/10/sys/netinet6/frag6.c 329158 2018-02-12 13:52:58Z ae $");
   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 #include <net/vnet.h>
   50 
   51 #include <netinet/in.h>
   52 #include <netinet/in_var.h>
   53 #include <netinet/ip6.h>
   54 #include <netinet6/ip6_var.h>
   55 #include <netinet/icmp6.h>
   56 #include <netinet/in_systm.h>   /* for ECN definitions */
   57 #include <netinet/ip.h>         /* for ECN definitions */
   58 
   59 #include <security/mac/mac_framework.h>
   60 
   61 /*
   62  * Define it to get a correct behavior on per-interface statistics.
   63  * You will need to perform an extra routing table lookup, per fragment,
   64  * to do it.  This may, or may not be, a performance hit.
   65  */
   66 #define IN6_IFSTAT_STRICT
   67 
   68 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
   69 static void frag6_deq(struct ip6asfrag *);
   70 static void frag6_insque(struct ip6q *, struct ip6q *);
   71 static void frag6_remque(struct ip6q *);
   72 static void frag6_freef(struct ip6q *);
   73 
   74 static struct mtx ip6qlock;
   75 /*
   76  * These fields all protected by ip6qlock.
   77  */
   78 static VNET_DEFINE(u_int, frag6_nfragpackets);
   79 static VNET_DEFINE(u_int, frag6_nfrags);
   80 static VNET_DEFINE(struct ip6q, ip6q);  /* ip6 reassemble queue */
   81 
   82 #define V_frag6_nfragpackets            VNET(frag6_nfragpackets)
   83 #define V_frag6_nfrags                  VNET(frag6_nfrags)
   84 #define V_ip6q                          VNET(ip6q)
   85 
   86 #define IP6Q_LOCK_INIT()        mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
   87 #define IP6Q_LOCK()             mtx_lock(&ip6qlock)
   88 #define IP6Q_TRYLOCK()          mtx_trylock(&ip6qlock)
   89 #define IP6Q_LOCK_ASSERT()      mtx_assert(&ip6qlock, MA_OWNED)
   90 #define IP6Q_UNLOCK()           mtx_unlock(&ip6qlock)
   91 
   92 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
   93 
   94 /*
   95  * Initialise reassembly queue and fragment identifier.
   96  */
   97 static void
   98 frag6_change(void *tag)
   99 {
  100 
  101         V_ip6_maxfragpackets = nmbclusters / 4;
  102         V_ip6_maxfrags = nmbclusters / 4;
  103 }
  104 
  105 void
  106 frag6_init(void)
  107 {
  108 
  109         V_ip6_maxfragpackets = nmbclusters / 4;
  110         V_ip6_maxfrags = nmbclusters / 4;
  111         V_ip6q.ip6q_next = V_ip6q.ip6q_prev = &V_ip6q;
  112 
  113         if (!IS_DEFAULT_VNET(curvnet))
  114                 return;
  115 
  116         EVENTHANDLER_REGISTER(nmbclusters_change,
  117             frag6_change, NULL, EVENTHANDLER_PRI_ANY);
  118 
  119         IP6Q_LOCK_INIT();
  120 }
  121 
  122 /*
  123  * In RFC2460, fragment and reassembly rule do not agree with each other,
  124  * in terms of next header field handling in fragment header.
  125  * While the sender will use the same value for all of the fragmented packets,
  126  * receiver is suggested not to check the consistency.
  127  *
  128  * fragment rule (p20):
  129  *      (2) A Fragment header containing:
  130  *      The Next Header value that identifies the first header of
  131  *      the Fragmentable Part of the original packet.
  132  *              -> next header field is same for all fragments
  133  *
  134  * reassembly rule (p21):
  135  *      The Next Header field of the last header of the Unfragmentable
  136  *      Part is obtained from the Next Header field of the first
  137  *      fragment's Fragment header.
  138  *              -> should grab it from the first fragment only
  139  *
  140  * The following note also contradicts with fragment rule - noone is going to
  141  * send different fragment with different next header field.
  142  *
  143  * additional note (p22):
  144  *      The Next Header values in the Fragment headers of different
  145  *      fragments of the same original packet may differ.  Only the value
  146  *      from the Offset zero fragment packet is used for reassembly.
  147  *              -> should grab it from the first fragment only
  148  *
  149  * There is no explicit reason given in the RFC.  Historical reason maybe?
  150  */
  151 /*
  152  * Fragment input
  153  */
  154 int
  155 frag6_input(struct mbuf **mp, int *offp, int proto)
  156 {
  157         struct mbuf *m = *mp, *t;
  158         struct ip6_hdr *ip6;
  159         struct ip6_frag *ip6f;
  160         struct ip6q *q6;
  161         struct ip6asfrag *af6, *ip6af, *af6dwn;
  162 #ifdef IN6_IFSTAT_STRICT
  163         struct in6_ifaddr *ia;
  164 #endif
  165         int offset = *offp, nxt, i, next;
  166         int first_frag = 0;
  167         int fragoff, frgpartlen;        /* must be larger than u_int16_t */
  168         struct ifnet *dstifp;
  169         u_int8_t ecn, ecn0;
  170 #if 0
  171         char ip6buf[INET6_ADDRSTRLEN];
  172 #endif
  173 
  174         ip6 = mtod(m, struct ip6_hdr *);
  175 #ifndef PULLDOWN_TEST
  176         IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
  177         ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
  178 #else
  179         IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
  180         if (ip6f == NULL)
  181                 return (IPPROTO_DONE);
  182 #endif
  183 
  184         dstifp = NULL;
  185 #ifdef IN6_IFSTAT_STRICT
  186         /* find the destination interface of the packet. */
  187         if ((ia = ip6_getdstifaddr(m)) != NULL) {
  188                 dstifp = ia->ia_ifp;
  189                 ifa_free(&ia->ia_ifa);
  190         }
  191 #else
  192         /* we are violating the spec, this is not the destination interface */
  193         if ((m->m_flags & M_PKTHDR) != 0)
  194                 dstifp = m->m_pkthdr.rcvif;
  195 #endif
  196 
  197         /* jumbo payload can't contain a fragment header */
  198         if (ip6->ip6_plen == 0) {
  199                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
  200                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  201                 return IPPROTO_DONE;
  202         }
  203 
  204         /*
  205          * check whether fragment packet's fragment length is
  206          * multiple of 8 octets.
  207          * sizeof(struct ip6_frag) == 8
  208          * sizeof(struct ip6_hdr) = 40
  209          */
  210         if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
  211             (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
  212                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  213                     offsetof(struct ip6_hdr, ip6_plen));
  214                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  215                 return IPPROTO_DONE;
  216         }
  217 
  218         IP6STAT_INC(ip6s_fragments);
  219         in6_ifstat_inc(dstifp, ifs6_reass_reqd);
  220 
  221         /* offset now points to data portion */
  222         offset += sizeof(struct ip6_frag);
  223 
  224         /*
  225          * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0)
  226          * upfront, unrelated to any reassembly.  Just skip the fragment header.
  227          */
  228         if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
  229                 /* XXX-BZ we want dedicated counters for this. */
  230                 IP6STAT_INC(ip6s_reassembled);
  231                 in6_ifstat_inc(dstifp, ifs6_reass_ok);
  232                 *offp = offset;
  233                 return (ip6f->ip6f_nxt);
  234         }
  235 
  236         IP6Q_LOCK();
  237 
  238         /*
  239          * Enforce upper bound on number of fragments.
  240          * If maxfrag is 0, never accept fragments.
  241          * If maxfrag is -1, accept all fragments without limitation.
  242          */
  243         if (V_ip6_maxfrags < 0)
  244                 ;
  245         else if (V_frag6_nfrags >= (u_int)V_ip6_maxfrags)
  246                 goto dropfrag;
  247 
  248         for (q6 = V_ip6q.ip6q_next; q6 != &V_ip6q; q6 = q6->ip6q_next)
  249                 if (ip6f->ip6f_ident == q6->ip6q_ident &&
  250                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
  251                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
  252 #ifdef MAC
  253                     && mac_ip6q_match(m, q6)
  254 #endif
  255                     )
  256                         break;
  257 
  258         if (q6 == &V_ip6q) {
  259                 /*
  260                  * the first fragment to arrive, create a reassembly queue.
  261                  */
  262                 first_frag = 1;
  263 
  264                 /*
  265                  * Enforce upper bound on number of fragmented packets
  266                  * for which we attempt reassembly;
  267                  * If maxfragpackets is 0, never accept fragments.
  268                  * If maxfragpackets is -1, accept all fragments without
  269                  * limitation.
  270                  */
  271                 if (V_ip6_maxfragpackets < 0)
  272                         ;
  273                 else if (V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets)
  274                         goto dropfrag;
  275                 V_frag6_nfragpackets++;
  276                 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
  277                     M_NOWAIT);
  278                 if (q6 == NULL)
  279                         goto dropfrag;
  280                 bzero(q6, sizeof(*q6));
  281 #ifdef MAC
  282                 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
  283                         free(q6, M_FTABLE);
  284                         goto dropfrag;
  285                 }
  286                 mac_ip6q_create(m, q6);
  287 #endif
  288                 frag6_insque(q6, &V_ip6q);
  289 
  290                 /* ip6q_nxt will be filled afterwards, from 1st fragment */
  291                 q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
  292 #ifdef notyet
  293                 q6->ip6q_nxtp   = (u_char *)nxtp;
  294 #endif
  295                 q6->ip6q_ident  = ip6f->ip6f_ident;
  296                 q6->ip6q_ttl    = IPV6_FRAGTTL;
  297                 q6->ip6q_src    = ip6->ip6_src;
  298                 q6->ip6q_dst    = ip6->ip6_dst;
  299                 q6->ip6q_ecn    =
  300                     (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  301                 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
  302 
  303                 q6->ip6q_nfrag = 0;
  304         }
  305 
  306         /*
  307          * If it's the 1st fragment, record the length of the
  308          * unfragmentable part and the next header of the fragment header.
  309          */
  310         fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
  311         if (fragoff == 0) {
  312                 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
  313                     sizeof(struct ip6_frag);
  314                 q6->ip6q_nxt = ip6f->ip6f_nxt;
  315         }
  316 
  317         /*
  318          * Check that the reassembled packet would not exceed 65535 bytes
  319          * in size.
  320          * If it would exceed, discard the fragment and return an ICMP error.
  321          */
  322         frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
  323         if (q6->ip6q_unfrglen >= 0) {
  324                 /* The 1st fragment has already arrived. */
  325                 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
  326                         icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  327                             offset - sizeof(struct ip6_frag) +
  328                             offsetof(struct ip6_frag, ip6f_offlg));
  329                         IP6Q_UNLOCK();
  330                         return (IPPROTO_DONE);
  331                 }
  332         } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
  333                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  334                     offset - sizeof(struct ip6_frag) +
  335                     offsetof(struct ip6_frag, ip6f_offlg));
  336                 IP6Q_UNLOCK();
  337                 return (IPPROTO_DONE);
  338         }
  339         /*
  340          * If it's the first fragment, do the above check for each
  341          * fragment already stored in the reassembly queue.
  342          */
  343         if (fragoff == 0) {
  344                 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  345                      af6 = af6dwn) {
  346                         af6dwn = af6->ip6af_down;
  347 
  348                         if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
  349                             IPV6_MAXPACKET) {
  350                                 struct mbuf *merr = IP6_REASS_MBUF(af6);
  351                                 struct ip6_hdr *ip6err;
  352                                 int erroff = af6->ip6af_offset;
  353 
  354                                 /* dequeue the fragment. */
  355                                 frag6_deq(af6);
  356                                 free(af6, M_FTABLE);
  357 
  358                                 /* adjust pointer. */
  359                                 ip6err = mtod(merr, struct ip6_hdr *);
  360 
  361                                 /*
  362                                  * Restore source and destination addresses
  363                                  * in the erroneous IPv6 header.
  364                                  */
  365                                 ip6err->ip6_src = q6->ip6q_src;
  366                                 ip6err->ip6_dst = q6->ip6q_dst;
  367 
  368                                 icmp6_error(merr, ICMP6_PARAM_PROB,
  369                                     ICMP6_PARAMPROB_HEADER,
  370                                     erroff - sizeof(struct ip6_frag) +
  371                                     offsetof(struct ip6_frag, ip6f_offlg));
  372                         }
  373                 }
  374         }
  375 
  376         ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
  377             M_NOWAIT);
  378         if (ip6af == NULL)
  379                 goto dropfrag;
  380         bzero(ip6af, sizeof(*ip6af));
  381         ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
  382         ip6af->ip6af_off = fragoff;
  383         ip6af->ip6af_frglen = frgpartlen;
  384         ip6af->ip6af_offset = offset;
  385         IP6_REASS_MBUF(ip6af) = m;
  386 
  387         if (first_frag) {
  388                 af6 = (struct ip6asfrag *)q6;
  389                 goto insert;
  390         }
  391 
  392         /*
  393          * Handle ECN by comparing this segment with the first one;
  394          * if CE is set, do not lose CE.
  395          * drop if CE and not-ECT are mixed for the same packet.
  396          */
  397         ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  398         ecn0 = q6->ip6q_ecn;
  399         if (ecn == IPTOS_ECN_CE) {
  400                 if (ecn0 == IPTOS_ECN_NOTECT) {
  401                         free(ip6af, M_FTABLE);
  402                         goto dropfrag;
  403                 }
  404                 if (ecn0 != IPTOS_ECN_CE)
  405                         q6->ip6q_ecn = IPTOS_ECN_CE;
  406         }
  407         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
  408                 free(ip6af, M_FTABLE);
  409                 goto dropfrag;
  410         }
  411 
  412         /*
  413          * Find a segment which begins after this one does.
  414          */
  415         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  416              af6 = af6->ip6af_down)
  417                 if (af6->ip6af_off > ip6af->ip6af_off)
  418                         break;
  419 
  420 #if 0
  421         /*
  422          * If there is a preceding segment, it may provide some of
  423          * our data already.  If so, drop the data from the incoming
  424          * segment.  If it provides all of our data, drop us.
  425          */
  426         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  427                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  428                         - ip6af->ip6af_off;
  429                 if (i > 0) {
  430                         if (i >= ip6af->ip6af_frglen)
  431                                 goto dropfrag;
  432                         m_adj(IP6_REASS_MBUF(ip6af), i);
  433                         ip6af->ip6af_off += i;
  434                         ip6af->ip6af_frglen -= i;
  435                 }
  436         }
  437 
  438         /*
  439          * While we overlap succeeding segments trim them or,
  440          * if they are completely covered, dequeue them.
  441          */
  442         while (af6 != (struct ip6asfrag *)q6 &&
  443                ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
  444                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  445                 if (i < af6->ip6af_frglen) {
  446                         af6->ip6af_frglen -= i;
  447                         af6->ip6af_off += i;
  448                         m_adj(IP6_REASS_MBUF(af6), i);
  449                         break;
  450                 }
  451                 af6 = af6->ip6af_down;
  452                 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
  453                 frag6_deq(af6->ip6af_up);
  454         }
  455 #else
  456         /*
  457          * If the incoming framgent overlaps some existing fragments in
  458          * the reassembly queue, drop it, since it is dangerous to override
  459          * existing fragments from a security point of view.
  460          * We don't know which fragment is the bad guy - here we trust
  461          * fragment that came in earlier, with no real reason.
  462          *
  463          * Note: due to changes after disabling this part, mbuf passed to
  464          * m_adj() below now does not meet the requirement.
  465          */
  466         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  467                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  468                         - ip6af->ip6af_off;
  469                 if (i > 0) {
  470 #if 0                           /* suppress the noisy log */
  471                         log(LOG_ERR, "%d bytes of a fragment from %s "
  472                             "overlaps the previous fragment\n",
  473                             i, ip6_sprintf(ip6buf, &q6->ip6q_src));
  474 #endif
  475                         free(ip6af, M_FTABLE);
  476                         goto dropfrag;
  477                 }
  478         }
  479         if (af6 != (struct ip6asfrag *)q6) {
  480                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  481                 if (i > 0) {
  482 #if 0                           /* suppress the noisy log */
  483                         log(LOG_ERR, "%d bytes of a fragment from %s "
  484                             "overlaps the succeeding fragment",
  485                             i, ip6_sprintf(ip6buf, &q6->ip6q_src));
  486 #endif
  487                         free(ip6af, M_FTABLE);
  488                         goto dropfrag;
  489                 }
  490         }
  491 #endif
  492 
  493 insert:
  494 #ifdef MAC
  495         if (!first_frag)
  496                 mac_ip6q_update(m, q6);
  497 #endif
  498 
  499         /*
  500          * Stick new segment in its place;
  501          * check for complete reassembly.
  502          * Move to front of packet queue, as we are
  503          * the most recently active fragmented packet.
  504          */
  505         frag6_enq(ip6af, af6->ip6af_up);
  506         V_frag6_nfrags++;
  507         q6->ip6q_nfrag++;
  508 #if 0 /* xxx */
  509         if (q6 != V_ip6q.ip6q_next) {
  510                 frag6_remque(q6);
  511                 frag6_insque(q6, &V_ip6q);
  512         }
  513 #endif
  514         next = 0;
  515         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  516              af6 = af6->ip6af_down) {
  517                 if (af6->ip6af_off != next) {
  518                         IP6Q_UNLOCK();
  519                         return IPPROTO_DONE;
  520                 }
  521                 next += af6->ip6af_frglen;
  522         }
  523         if (af6->ip6af_up->ip6af_mff) {
  524                 IP6Q_UNLOCK();
  525                 return IPPROTO_DONE;
  526         }
  527 
  528         /*
  529          * Reassembly is complete; concatenate fragments.
  530          */
  531         ip6af = q6->ip6q_down;
  532         t = m = IP6_REASS_MBUF(ip6af);
  533         af6 = ip6af->ip6af_down;
  534         frag6_deq(ip6af);
  535         while (af6 != (struct ip6asfrag *)q6) {
  536                 m->m_pkthdr.csum_flags &=
  537                     IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags;
  538                 m->m_pkthdr.csum_data +=
  539                     IP6_REASS_MBUF(af6)->m_pkthdr.csum_data;
  540 
  541                 af6dwn = af6->ip6af_down;
  542                 frag6_deq(af6);
  543                 while (t->m_next)
  544                         t = t->m_next;
  545                 t->m_next = IP6_REASS_MBUF(af6);
  546                 m_adj(t->m_next, af6->ip6af_offset);
  547                 free(af6, M_FTABLE);
  548                 af6 = af6dwn;
  549         }
  550 
  551         while (m->m_pkthdr.csum_data & 0xffff0000)
  552                 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
  553                     (m->m_pkthdr.csum_data >> 16);
  554 
  555         /* adjust offset to point where the original next header starts */
  556         offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
  557         free(ip6af, M_FTABLE);
  558         ip6 = mtod(m, struct ip6_hdr *);
  559         ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
  560         if (q6->ip6q_ecn == IPTOS_ECN_CE)
  561                 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
  562         nxt = q6->ip6q_nxt;
  563 #ifdef notyet
  564         *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
  565 #endif
  566 
  567         if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) {
  568                 frag6_remque(q6);
  569                 V_frag6_nfrags -= q6->ip6q_nfrag;
  570 #ifdef MAC
  571                 mac_ip6q_destroy(q6);
  572 #endif
  573                 free(q6, M_FTABLE);
  574                 V_frag6_nfragpackets--;
  575 
  576                 goto dropfrag;
  577         }
  578 
  579         /*
  580          * Store NXT to the original.
  581          */
  582         m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
  583             (caddr_t)&nxt);
  584 
  585         frag6_remque(q6);
  586         V_frag6_nfrags -= q6->ip6q_nfrag;
  587 #ifdef MAC
  588         mac_ip6q_reassemble(q6, m);
  589         mac_ip6q_destroy(q6);
  590 #endif
  591         free(q6, M_FTABLE);
  592         V_frag6_nfragpackets--;
  593 
  594         if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
  595                 int plen = 0;
  596                 for (t = m; t; t = t->m_next)
  597                         plen += t->m_len;
  598                 m->m_pkthdr.len = plen;
  599         }
  600 
  601         IP6STAT_INC(ip6s_reassembled);
  602         in6_ifstat_inc(dstifp, ifs6_reass_ok);
  603 
  604         /*
  605          * Tell launch routine the next header
  606          */
  607 
  608         *mp = m;
  609         *offp = offset;
  610 
  611         IP6Q_UNLOCK();
  612         return nxt;
  613 
  614  dropfrag:
  615         IP6Q_UNLOCK();
  616         in6_ifstat_inc(dstifp, ifs6_reass_fail);
  617         IP6STAT_INC(ip6s_fragdropped);
  618         m_freem(m);
  619         return IPPROTO_DONE;
  620 }
  621 
  622 /*
  623  * Free a fragment reassembly header and all
  624  * associated datagrams.
  625  */
  626 void
  627 frag6_freef(struct ip6q *q6)
  628 {
  629         struct ip6asfrag *af6, *down6;
  630 
  631         IP6Q_LOCK_ASSERT();
  632 
  633         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  634              af6 = down6) {
  635                 struct mbuf *m = IP6_REASS_MBUF(af6);
  636 
  637                 down6 = af6->ip6af_down;
  638                 frag6_deq(af6);
  639 
  640                 /*
  641                  * Return ICMP time exceeded error for the 1st fragment.
  642                  * Just free other fragments.
  643                  */
  644                 if (af6->ip6af_off == 0) {
  645                         struct ip6_hdr *ip6;
  646 
  647                         /* adjust pointer */
  648                         ip6 = mtod(m, struct ip6_hdr *);
  649 
  650                         /* restore source and destination addresses */
  651                         ip6->ip6_src = q6->ip6q_src;
  652                         ip6->ip6_dst = q6->ip6q_dst;
  653 
  654                         icmp6_error(m, ICMP6_TIME_EXCEEDED,
  655                                     ICMP6_TIME_EXCEED_REASSEMBLY, 0);
  656                 } else
  657                         m_freem(m);
  658                 free(af6, M_FTABLE);
  659         }
  660         frag6_remque(q6);
  661         V_frag6_nfrags -= q6->ip6q_nfrag;
  662 #ifdef MAC
  663         mac_ip6q_destroy(q6);
  664 #endif
  665         free(q6, M_FTABLE);
  666         V_frag6_nfragpackets--;
  667 }
  668 
  669 /*
  670  * Put an ip fragment on a reassembly chain.
  671  * Like insque, but pointers in middle of structure.
  672  */
  673 void
  674 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
  675 {
  676 
  677         IP6Q_LOCK_ASSERT();
  678 
  679         af6->ip6af_up = up6;
  680         af6->ip6af_down = up6->ip6af_down;
  681         up6->ip6af_down->ip6af_up = af6;
  682         up6->ip6af_down = af6;
  683 }
  684 
  685 /*
  686  * To frag6_enq as remque is to insque.
  687  */
  688 void
  689 frag6_deq(struct ip6asfrag *af6)
  690 {
  691 
  692         IP6Q_LOCK_ASSERT();
  693 
  694         af6->ip6af_up->ip6af_down = af6->ip6af_down;
  695         af6->ip6af_down->ip6af_up = af6->ip6af_up;
  696 }
  697 
  698 void
  699 frag6_insque(struct ip6q *new, struct ip6q *old)
  700 {
  701 
  702         IP6Q_LOCK_ASSERT();
  703 
  704         new->ip6q_prev = old;
  705         new->ip6q_next = old->ip6q_next;
  706         old->ip6q_next->ip6q_prev= new;
  707         old->ip6q_next = new;
  708 }
  709 
  710 void
  711 frag6_remque(struct ip6q *p6)
  712 {
  713 
  714         IP6Q_LOCK_ASSERT();
  715 
  716         p6->ip6q_prev->ip6q_next = p6->ip6q_next;
  717         p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
  718 }
  719 
  720 /*
  721  * IPv6 reassembling timer processing;
  722  * if a timer expires on a reassembly
  723  * queue, discard it.
  724  */
  725 void
  726 frag6_slowtimo(void)
  727 {
  728         VNET_ITERATOR_DECL(vnet_iter);
  729         struct ip6q *q6;
  730 
  731         VNET_LIST_RLOCK_NOSLEEP();
  732         IP6Q_LOCK();
  733         VNET_FOREACH(vnet_iter) {
  734                 CURVNET_SET(vnet_iter);
  735                 q6 = V_ip6q.ip6q_next;
  736                 if (q6)
  737                         while (q6 != &V_ip6q) {
  738                                 --q6->ip6q_ttl;
  739                                 q6 = q6->ip6q_next;
  740                                 if (q6->ip6q_prev->ip6q_ttl == 0) {
  741                                         IP6STAT_INC(ip6s_fragtimeout);
  742                                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  743                                         frag6_freef(q6->ip6q_prev);
  744                                 }
  745                         }
  746                 /*
  747                  * If we are over the maximum number of fragments
  748                  * (due to the limit being lowered), drain off
  749                  * enough to get down to the new limit.
  750                  */
  751                 while (V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets &&
  752                     V_ip6q.ip6q_prev) {
  753                         IP6STAT_INC(ip6s_fragoverflow);
  754                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  755                         frag6_freef(V_ip6q.ip6q_prev);
  756                 }
  757                 CURVNET_RESTORE();
  758         }
  759         IP6Q_UNLOCK();
  760         VNET_LIST_RUNLOCK_NOSLEEP();
  761 }
  762 
  763 /*
  764  * Drain off all datagram fragments.
  765  */
  766 void
  767 frag6_drain(void)
  768 {
  769         VNET_ITERATOR_DECL(vnet_iter);
  770 
  771         VNET_LIST_RLOCK_NOSLEEP();
  772         if (IP6Q_TRYLOCK() == 0) {
  773                 VNET_LIST_RUNLOCK_NOSLEEP();
  774                 return;
  775         }
  776         VNET_FOREACH(vnet_iter) {
  777                 CURVNET_SET(vnet_iter);
  778                 while (V_ip6q.ip6q_next != &V_ip6q) {
  779                         IP6STAT_INC(ip6s_fragdropped);
  780                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  781                         frag6_freef(V_ip6q.ip6q_next);
  782                 }
  783                 CURVNET_RESTORE();
  784         }
  785         IP6Q_UNLOCK();
  786         VNET_LIST_RUNLOCK_NOSLEEP();
  787 }
  788 
  789 int
  790 ip6_deletefraghdr(struct mbuf *m, int offset, int wait)
  791 {
  792         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  793         struct mbuf *t;
  794 
  795         /* Delete frag6 header. */
  796         if (m->m_len >= offset + sizeof(struct ip6_frag)) {
  797                 /* This is the only possible case with !PULLDOWN_TEST. */
  798                 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag),
  799                     offset);
  800                 m->m_data += sizeof(struct ip6_frag);
  801                 m->m_len -= sizeof(struct ip6_frag);
  802         } else {
  803                 /* This comes with no copy if the boundary is on cluster. */
  804                 if ((t = m_split(m, offset, wait)) == NULL)
  805                         return (ENOMEM);
  806                 m_adj(t, sizeof(struct ip6_frag));
  807                 m_cat(m, t);
  808         }
  809 
  810         return (0);
  811 }

Cache object: 53db0043cf05414ce4fae9f1d852d48a


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