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/11.0/sys/netinet6/frag6.c 298995 2016-05-03 18:05:43Z pfg $");
   34 
   35 #include "opt_rss.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/malloc.h>
   40 #include <sys/mbuf.h>
   41 #include <sys/domain.h>
   42 #include <sys/eventhandler.h>
   43 #include <sys/protosw.h>
   44 #include <sys/socket.h>
   45 #include <sys/errno.h>
   46 #include <sys/time.h>
   47 #include <sys/kernel.h>
   48 #include <sys/syslog.h>
   49 
   50 #include <net/if.h>
   51 #include <net/if_var.h>
   52 #include <net/netisr.h>
   53 #include <net/route.h>
   54 #include <net/vnet.h>
   55 
   56 #include <netinet/in.h>
   57 #include <netinet/in_var.h>
   58 #include <netinet/ip6.h>
   59 #include <netinet6/ip6_var.h>
   60 #include <netinet/icmp6.h>
   61 #include <netinet/in_systm.h>   /* for ECN definitions */
   62 #include <netinet/ip.h>         /* for ECN definitions */
   63 
   64 #include <security/mac/mac_framework.h>
   65 
   66 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
   67 static void frag6_deq(struct ip6asfrag *);
   68 static void frag6_insque(struct ip6q *, struct ip6q *);
   69 static void frag6_remque(struct ip6q *);
   70 static void frag6_freef(struct ip6q *);
   71 
   72 static struct mtx ip6qlock;
   73 /*
   74  * These fields all protected by ip6qlock.
   75  */
   76 static VNET_DEFINE(u_int, frag6_nfragpackets);
   77 static VNET_DEFINE(u_int, frag6_nfrags);
   78 static VNET_DEFINE(struct ip6q, ip6q);  /* ip6 reassemble queue */
   79 
   80 #define V_frag6_nfragpackets            VNET(frag6_nfragpackets)
   81 #define V_frag6_nfrags                  VNET(frag6_nfrags)
   82 #define V_ip6q                          VNET(ip6q)
   83 
   84 #define IP6Q_LOCK_INIT()        mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
   85 #define IP6Q_LOCK()             mtx_lock(&ip6qlock)
   86 #define IP6Q_TRYLOCK()          mtx_trylock(&ip6qlock)
   87 #define IP6Q_LOCK_ASSERT()      mtx_assert(&ip6qlock, MA_OWNED)
   88 #define IP6Q_UNLOCK()           mtx_unlock(&ip6qlock)
   89 
   90 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
   91 
   92 /*
   93  * Initialise reassembly queue and fragment identifier.
   94  */
   95 static void
   96 frag6_change(void *tag)
   97 {
   98 
   99         V_ip6_maxfragpackets = nmbclusters / 4;
  100         V_ip6_maxfrags = nmbclusters / 4;
  101 }
  102 
  103 void
  104 frag6_init(void)
  105 {
  106 
  107         V_ip6_maxfragpackets = nmbclusters / 4;
  108         V_ip6_maxfrags = nmbclusters / 4;
  109         V_ip6q.ip6q_next = V_ip6q.ip6q_prev = &V_ip6q;
  110 
  111         if (!IS_DEFAULT_VNET(curvnet))
  112                 return;
  113 
  114         EVENTHANDLER_REGISTER(nmbclusters_change,
  115             frag6_change, NULL, EVENTHANDLER_PRI_ANY);
  116 
  117         IP6Q_LOCK_INIT();
  118 }
  119 
  120 /*
  121  * In RFC2460, fragment and reassembly rule do not agree with each other,
  122  * in terms of next header field handling in fragment header.
  123  * While the sender will use the same value for all of the fragmented packets,
  124  * receiver is suggested not to check the consistency.
  125  *
  126  * fragment rule (p20):
  127  *      (2) A Fragment header containing:
  128  *      The Next Header value that identifies the first header of
  129  *      the Fragmentable Part of the original packet.
  130  *              -> next header field is same for all fragments
  131  *
  132  * reassembly rule (p21):
  133  *      The Next Header field of the last header of the Unfragmentable
  134  *      Part is obtained from the Next Header field of the first
  135  *      fragment's Fragment header.
  136  *              -> should grab it from the first fragment only
  137  *
  138  * The following note also contradicts with fragment rule - no one is going to
  139  * send different fragment with different next header field.
  140  *
  141  * additional note (p22):
  142  *      The Next Header values in the Fragment headers of different
  143  *      fragments of the same original packet may differ.  Only the value
  144  *      from the Offset zero fragment packet is used for reassembly.
  145  *              -> should grab it from the first fragment only
  146  *
  147  * There is no explicit reason given in the RFC.  Historical reason maybe?
  148  */
  149 /*
  150  * Fragment input
  151  */
  152 int
  153 frag6_input(struct mbuf **mp, int *offp, int proto)
  154 {
  155         struct mbuf *m = *mp, *t;
  156         struct ip6_hdr *ip6;
  157         struct ip6_frag *ip6f;
  158         struct ip6q *q6;
  159         struct ip6asfrag *af6, *ip6af, *af6dwn;
  160         struct in6_ifaddr *ia;
  161         int offset = *offp, nxt, i, next;
  162         int first_frag = 0;
  163         int fragoff, frgpartlen;        /* must be larger than u_int16_t */
  164         struct ifnet *dstifp;
  165         u_int8_t ecn, ecn0;
  166 #ifdef RSS
  167         struct m_tag *mtag;
  168         struct ip6_direct_ctx *ip6dc;
  169 #endif
  170 
  171 #if 0
  172         char ip6buf[INET6_ADDRSTRLEN];
  173 #endif
  174 
  175         ip6 = mtod(m, struct ip6_hdr *);
  176 #ifndef PULLDOWN_TEST
  177         IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
  178         ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
  179 #else
  180         IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
  181         if (ip6f == NULL)
  182                 return (IPPROTO_DONE);
  183 #endif
  184 
  185         dstifp = NULL;
  186         /* find the destination interface of the packet. */
  187         ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */);
  188         if (ia != NULL) {
  189                 dstifp = ia->ia_ifp;
  190                 ifa_free(&ia->ia_ifa);
  191         }
  192         /* jumbo payload can't contain a fragment header */
  193         if (ip6->ip6_plen == 0) {
  194                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
  195                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  196                 return IPPROTO_DONE;
  197         }
  198 
  199         /*
  200          * check whether fragment packet's fragment length is
  201          * multiple of 8 octets.
  202          * sizeof(struct ip6_frag) == 8
  203          * sizeof(struct ip6_hdr) = 40
  204          */
  205         if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
  206             (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
  207                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  208                     offsetof(struct ip6_hdr, ip6_plen));
  209                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  210                 return IPPROTO_DONE;
  211         }
  212 
  213         IP6STAT_INC(ip6s_fragments);
  214         in6_ifstat_inc(dstifp, ifs6_reass_reqd);
  215 
  216         /* offset now points to data portion */
  217         offset += sizeof(struct ip6_frag);
  218 
  219         /*
  220          * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0)
  221          * upfront, unrelated to any reassembly.  Just skip the fragment header.
  222          */
  223         if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
  224                 /* XXX-BZ we want dedicated counters for this. */
  225                 IP6STAT_INC(ip6s_reassembled);
  226                 in6_ifstat_inc(dstifp, ifs6_reass_ok);
  227                 *offp = offset;
  228                 return (ip6f->ip6f_nxt);
  229         }
  230 
  231         IP6Q_LOCK();
  232 
  233         /*
  234          * Enforce upper bound on number of fragments.
  235          * If maxfrag is 0, never accept fragments.
  236          * If maxfrag is -1, accept all fragments without limitation.
  237          */
  238         if (V_ip6_maxfrags < 0)
  239                 ;
  240         else if (V_frag6_nfrags >= (u_int)V_ip6_maxfrags)
  241                 goto dropfrag;
  242 
  243         for (q6 = V_ip6q.ip6q_next; q6 != &V_ip6q; q6 = q6->ip6q_next)
  244                 if (ip6f->ip6f_ident == q6->ip6q_ident &&
  245                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
  246                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
  247 #ifdef MAC
  248                     && mac_ip6q_match(m, q6)
  249 #endif
  250                     )
  251                         break;
  252 
  253         if (q6 == &V_ip6q) {
  254                 /*
  255                  * the first fragment to arrive, create a reassembly queue.
  256                  */
  257                 first_frag = 1;
  258 
  259                 /*
  260                  * Enforce upper bound on number of fragmented packets
  261                  * for which we attempt reassembly;
  262                  * If maxfragpackets is 0, never accept fragments.
  263                  * If maxfragpackets is -1, accept all fragments without
  264                  * limitation.
  265                  */
  266                 if (V_ip6_maxfragpackets < 0)
  267                         ;
  268                 else if (V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets)
  269                         goto dropfrag;
  270                 V_frag6_nfragpackets++;
  271                 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
  272                     M_NOWAIT);
  273                 if (q6 == NULL)
  274                         goto dropfrag;
  275                 bzero(q6, sizeof(*q6));
  276 #ifdef MAC
  277                 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
  278                         free(q6, M_FTABLE);
  279                         goto dropfrag;
  280                 }
  281                 mac_ip6q_create(m, q6);
  282 #endif
  283                 frag6_insque(q6, &V_ip6q);
  284 
  285                 /* ip6q_nxt will be filled afterwards, from 1st fragment */
  286                 q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
  287 #ifdef notyet
  288                 q6->ip6q_nxtp   = (u_char *)nxtp;
  289 #endif
  290                 q6->ip6q_ident  = ip6f->ip6f_ident;
  291                 q6->ip6q_ttl    = IPV6_FRAGTTL;
  292                 q6->ip6q_src    = ip6->ip6_src;
  293                 q6->ip6q_dst    = ip6->ip6_dst;
  294                 q6->ip6q_ecn    =
  295                     (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  296                 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
  297 
  298                 q6->ip6q_nfrag = 0;
  299         }
  300 
  301         /*
  302          * If it's the 1st fragment, record the length of the
  303          * unfragmentable part and the next header of the fragment header.
  304          */
  305         fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
  306         if (fragoff == 0) {
  307                 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
  308                     sizeof(struct ip6_frag);
  309                 q6->ip6q_nxt = ip6f->ip6f_nxt;
  310         }
  311 
  312         /*
  313          * Check that the reassembled packet would not exceed 65535 bytes
  314          * in size.
  315          * If it would exceed, discard the fragment and return an ICMP error.
  316          */
  317         frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
  318         if (q6->ip6q_unfrglen >= 0) {
  319                 /* The 1st fragment has already arrived. */
  320                 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
  321                         icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  322                             offset - sizeof(struct ip6_frag) +
  323                             offsetof(struct ip6_frag, ip6f_offlg));
  324                         IP6Q_UNLOCK();
  325                         return (IPPROTO_DONE);
  326                 }
  327         } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
  328                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  329                     offset - sizeof(struct ip6_frag) +
  330                     offsetof(struct ip6_frag, ip6f_offlg));
  331                 IP6Q_UNLOCK();
  332                 return (IPPROTO_DONE);
  333         }
  334         /*
  335          * If it's the first fragment, do the above check for each
  336          * fragment already stored in the reassembly queue.
  337          */
  338         if (fragoff == 0) {
  339                 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  340                      af6 = af6dwn) {
  341                         af6dwn = af6->ip6af_down;
  342 
  343                         if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
  344                             IPV6_MAXPACKET) {
  345                                 struct mbuf *merr = IP6_REASS_MBUF(af6);
  346                                 struct ip6_hdr *ip6err;
  347                                 int erroff = af6->ip6af_offset;
  348 
  349                                 /* dequeue the fragment. */
  350                                 frag6_deq(af6);
  351                                 free(af6, M_FTABLE);
  352 
  353                                 /* adjust pointer. */
  354                                 ip6err = mtod(merr, struct ip6_hdr *);
  355 
  356                                 /*
  357                                  * Restore source and destination addresses
  358                                  * in the erroneous IPv6 header.
  359                                  */
  360                                 ip6err->ip6_src = q6->ip6q_src;
  361                                 ip6err->ip6_dst = q6->ip6q_dst;
  362 
  363                                 icmp6_error(merr, ICMP6_PARAM_PROB,
  364                                     ICMP6_PARAMPROB_HEADER,
  365                                     erroff - sizeof(struct ip6_frag) +
  366                                     offsetof(struct ip6_frag, ip6f_offlg));
  367                         }
  368                 }
  369         }
  370 
  371         ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
  372             M_NOWAIT);
  373         if (ip6af == NULL)
  374                 goto dropfrag;
  375         bzero(ip6af, sizeof(*ip6af));
  376         ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
  377         ip6af->ip6af_off = fragoff;
  378         ip6af->ip6af_frglen = frgpartlen;
  379         ip6af->ip6af_offset = offset;
  380         IP6_REASS_MBUF(ip6af) = m;
  381 
  382         if (first_frag) {
  383                 af6 = (struct ip6asfrag *)q6;
  384                 goto insert;
  385         }
  386 
  387         /*
  388          * Handle ECN by comparing this segment with the first one;
  389          * if CE is set, do not lose CE.
  390          * drop if CE and not-ECT are mixed for the same packet.
  391          */
  392         ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
  393         ecn0 = q6->ip6q_ecn;
  394         if (ecn == IPTOS_ECN_CE) {
  395                 if (ecn0 == IPTOS_ECN_NOTECT) {
  396                         free(ip6af, M_FTABLE);
  397                         goto dropfrag;
  398                 }
  399                 if (ecn0 != IPTOS_ECN_CE)
  400                         q6->ip6q_ecn = IPTOS_ECN_CE;
  401         }
  402         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
  403                 free(ip6af, M_FTABLE);
  404                 goto dropfrag;
  405         }
  406 
  407         /*
  408          * Find a segment which begins after this one does.
  409          */
  410         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  411              af6 = af6->ip6af_down)
  412                 if (af6->ip6af_off > ip6af->ip6af_off)
  413                         break;
  414 
  415 #if 0
  416         /*
  417          * If there is a preceding segment, it may provide some of
  418          * our data already.  If so, drop the data from the incoming
  419          * segment.  If it provides all of our data, drop us.
  420          */
  421         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  422                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  423                         - ip6af->ip6af_off;
  424                 if (i > 0) {
  425                         if (i >= ip6af->ip6af_frglen)
  426                                 goto dropfrag;
  427                         m_adj(IP6_REASS_MBUF(ip6af), i);
  428                         ip6af->ip6af_off += i;
  429                         ip6af->ip6af_frglen -= i;
  430                 }
  431         }
  432 
  433         /*
  434          * While we overlap succeeding segments trim them or,
  435          * if they are completely covered, dequeue them.
  436          */
  437         while (af6 != (struct ip6asfrag *)q6 &&
  438                ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
  439                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  440                 if (i < af6->ip6af_frglen) {
  441                         af6->ip6af_frglen -= i;
  442                         af6->ip6af_off += i;
  443                         m_adj(IP6_REASS_MBUF(af6), i);
  444                         break;
  445                 }
  446                 af6 = af6->ip6af_down;
  447                 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
  448                 frag6_deq(af6->ip6af_up);
  449         }
  450 #else
  451         /*
  452          * If the incoming framgent overlaps some existing fragments in
  453          * the reassembly queue, drop it, since it is dangerous to override
  454          * existing fragments from a security point of view.
  455          * We don't know which fragment is the bad guy - here we trust
  456          * fragment that came in earlier, with no real reason.
  457          *
  458          * Note: due to changes after disabling this part, mbuf passed to
  459          * m_adj() below now does not meet the requirement.
  460          */
  461         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  462                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  463                         - ip6af->ip6af_off;
  464                 if (i > 0) {
  465 #if 0                           /* suppress the noisy log */
  466                         log(LOG_ERR, "%d bytes of a fragment from %s "
  467                             "overlaps the previous fragment\n",
  468                             i, ip6_sprintf(ip6buf, &q6->ip6q_src));
  469 #endif
  470                         free(ip6af, M_FTABLE);
  471                         goto dropfrag;
  472                 }
  473         }
  474         if (af6 != (struct ip6asfrag *)q6) {
  475                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  476                 if (i > 0) {
  477 #if 0                           /* suppress the noisy log */
  478                         log(LOG_ERR, "%d bytes of a fragment from %s "
  479                             "overlaps the succeeding fragment",
  480                             i, ip6_sprintf(ip6buf, &q6->ip6q_src));
  481 #endif
  482                         free(ip6af, M_FTABLE);
  483                         goto dropfrag;
  484                 }
  485         }
  486 #endif
  487 
  488 insert:
  489 #ifdef MAC
  490         if (!first_frag)
  491                 mac_ip6q_update(m, q6);
  492 #endif
  493 
  494         /*
  495          * Stick new segment in its place;
  496          * check for complete reassembly.
  497          * Move to front of packet queue, as we are
  498          * the most recently active fragmented packet.
  499          */
  500         frag6_enq(ip6af, af6->ip6af_up);
  501         V_frag6_nfrags++;
  502         q6->ip6q_nfrag++;
  503 #if 0 /* xxx */
  504         if (q6 != V_ip6q.ip6q_next) {
  505                 frag6_remque(q6);
  506                 frag6_insque(q6, &V_ip6q);
  507         }
  508 #endif
  509         next = 0;
  510         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  511              af6 = af6->ip6af_down) {
  512                 if (af6->ip6af_off != next) {
  513                         IP6Q_UNLOCK();
  514                         return IPPROTO_DONE;
  515                 }
  516                 next += af6->ip6af_frglen;
  517         }
  518         if (af6->ip6af_up->ip6af_mff) {
  519                 IP6Q_UNLOCK();
  520                 return IPPROTO_DONE;
  521         }
  522 
  523         /*
  524          * Reassembly is complete; concatenate fragments.
  525          */
  526         ip6af = q6->ip6q_down;
  527         t = m = IP6_REASS_MBUF(ip6af);
  528         af6 = ip6af->ip6af_down;
  529         frag6_deq(ip6af);
  530         while (af6 != (struct ip6asfrag *)q6) {
  531                 af6dwn = af6->ip6af_down;
  532                 frag6_deq(af6);
  533                 while (t->m_next)
  534                         t = t->m_next;
  535                 m_adj(IP6_REASS_MBUF(af6), af6->ip6af_offset);
  536                 m_cat(t, IP6_REASS_MBUF(af6));
  537                 free(af6, M_FTABLE);
  538                 af6 = af6dwn;
  539         }
  540 
  541         /* adjust offset to point where the original next header starts */
  542         offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
  543         free(ip6af, M_FTABLE);
  544         ip6 = mtod(m, struct ip6_hdr *);
  545         ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
  546         if (q6->ip6q_ecn == IPTOS_ECN_CE)
  547                 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
  548         nxt = q6->ip6q_nxt;
  549 #ifdef notyet
  550         *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
  551 #endif
  552 
  553         if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) {
  554                 frag6_remque(q6);
  555                 V_frag6_nfrags -= q6->ip6q_nfrag;
  556 #ifdef MAC
  557                 mac_ip6q_destroy(q6);
  558 #endif
  559                 free(q6, M_FTABLE);
  560                 V_frag6_nfragpackets--;
  561 
  562                 goto dropfrag;
  563         }
  564 
  565         /*
  566          * Store NXT to the original.
  567          */
  568         {
  569                 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
  570                 *prvnxtp = nxt;
  571         }
  572 
  573         frag6_remque(q6);
  574         V_frag6_nfrags -= q6->ip6q_nfrag;
  575 #ifdef MAC
  576         mac_ip6q_reassemble(q6, m);
  577         mac_ip6q_destroy(q6);
  578 #endif
  579         free(q6, M_FTABLE);
  580         V_frag6_nfragpackets--;
  581 
  582         if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
  583                 int plen = 0;
  584                 for (t = m; t; t = t->m_next)
  585                         plen += t->m_len;
  586                 m->m_pkthdr.len = plen;
  587         }
  588 
  589 #ifdef RSS
  590         mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc),
  591             M_NOWAIT);
  592         if (mtag == NULL)
  593                 goto dropfrag;
  594 
  595         ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
  596         ip6dc->ip6dc_nxt = nxt;
  597         ip6dc->ip6dc_off = offset;
  598 
  599         m_tag_prepend(m, mtag);
  600 #endif
  601 
  602         IP6Q_UNLOCK();
  603         IP6STAT_INC(ip6s_reassembled);
  604         in6_ifstat_inc(dstifp, ifs6_reass_ok);
  605 
  606 #ifdef RSS
  607         /*
  608          * Queue/dispatch for reprocessing.
  609          */
  610         netisr_dispatch(NETISR_IPV6_DIRECT, m);
  611         return IPPROTO_DONE;
  612 #endif
  613 
  614         /*
  615          * Tell launch routine the next header
  616          */
  617 
  618         *mp = m;
  619         *offp = offset;
  620 
  621         return nxt;
  622 
  623  dropfrag:
  624         IP6Q_UNLOCK();
  625         in6_ifstat_inc(dstifp, ifs6_reass_fail);
  626         IP6STAT_INC(ip6s_fragdropped);
  627         m_freem(m);
  628         return IPPROTO_DONE;
  629 }
  630 
  631 /*
  632  * Free a fragment reassembly header and all
  633  * associated datagrams.
  634  */
  635 void
  636 frag6_freef(struct ip6q *q6)
  637 {
  638         struct ip6asfrag *af6, *down6;
  639 
  640         IP6Q_LOCK_ASSERT();
  641 
  642         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  643              af6 = down6) {
  644                 struct mbuf *m = IP6_REASS_MBUF(af6);
  645 
  646                 down6 = af6->ip6af_down;
  647                 frag6_deq(af6);
  648 
  649                 /*
  650                  * Return ICMP time exceeded error for the 1st fragment.
  651                  * Just free other fragments.
  652                  */
  653                 if (af6->ip6af_off == 0) {
  654                         struct ip6_hdr *ip6;
  655 
  656                         /* adjust pointer */
  657                         ip6 = mtod(m, struct ip6_hdr *);
  658 
  659                         /* restore source and destination addresses */
  660                         ip6->ip6_src = q6->ip6q_src;
  661                         ip6->ip6_dst = q6->ip6q_dst;
  662 
  663                         icmp6_error(m, ICMP6_TIME_EXCEEDED,
  664                                     ICMP6_TIME_EXCEED_REASSEMBLY, 0);
  665                 } else
  666                         m_freem(m);
  667                 free(af6, M_FTABLE);
  668         }
  669         frag6_remque(q6);
  670         V_frag6_nfrags -= q6->ip6q_nfrag;
  671 #ifdef MAC
  672         mac_ip6q_destroy(q6);
  673 #endif
  674         free(q6, M_FTABLE);
  675         V_frag6_nfragpackets--;
  676 }
  677 
  678 /*
  679  * Put an ip fragment on a reassembly chain.
  680  * Like insque, but pointers in middle of structure.
  681  */
  682 void
  683 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
  684 {
  685 
  686         IP6Q_LOCK_ASSERT();
  687 
  688         af6->ip6af_up = up6;
  689         af6->ip6af_down = up6->ip6af_down;
  690         up6->ip6af_down->ip6af_up = af6;
  691         up6->ip6af_down = af6;
  692 }
  693 
  694 /*
  695  * To frag6_enq as remque is to insque.
  696  */
  697 void
  698 frag6_deq(struct ip6asfrag *af6)
  699 {
  700 
  701         IP6Q_LOCK_ASSERT();
  702 
  703         af6->ip6af_up->ip6af_down = af6->ip6af_down;
  704         af6->ip6af_down->ip6af_up = af6->ip6af_up;
  705 }
  706 
  707 void
  708 frag6_insque(struct ip6q *new, struct ip6q *old)
  709 {
  710 
  711         IP6Q_LOCK_ASSERT();
  712 
  713         new->ip6q_prev = old;
  714         new->ip6q_next = old->ip6q_next;
  715         old->ip6q_next->ip6q_prev= new;
  716         old->ip6q_next = new;
  717 }
  718 
  719 void
  720 frag6_remque(struct ip6q *p6)
  721 {
  722 
  723         IP6Q_LOCK_ASSERT();
  724 
  725         p6->ip6q_prev->ip6q_next = p6->ip6q_next;
  726         p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
  727 }
  728 
  729 /*
  730  * IPv6 reassembling timer processing;
  731  * if a timer expires on a reassembly
  732  * queue, discard it.
  733  */
  734 void
  735 frag6_slowtimo(void)
  736 {
  737         VNET_ITERATOR_DECL(vnet_iter);
  738         struct ip6q *q6;
  739 
  740         VNET_LIST_RLOCK_NOSLEEP();
  741         IP6Q_LOCK();
  742         VNET_FOREACH(vnet_iter) {
  743                 CURVNET_SET(vnet_iter);
  744                 q6 = V_ip6q.ip6q_next;
  745                 if (q6)
  746                         while (q6 != &V_ip6q) {
  747                                 --q6->ip6q_ttl;
  748                                 q6 = q6->ip6q_next;
  749                                 if (q6->ip6q_prev->ip6q_ttl == 0) {
  750                                         IP6STAT_INC(ip6s_fragtimeout);
  751                                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  752                                         frag6_freef(q6->ip6q_prev);
  753                                 }
  754                         }
  755                 /*
  756                  * If we are over the maximum number of fragments
  757                  * (due to the limit being lowered), drain off
  758                  * enough to get down to the new limit.
  759                  */
  760                 while (V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets &&
  761                     V_ip6q.ip6q_prev) {
  762                         IP6STAT_INC(ip6s_fragoverflow);
  763                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  764                         frag6_freef(V_ip6q.ip6q_prev);
  765                 }
  766                 CURVNET_RESTORE();
  767         }
  768         IP6Q_UNLOCK();
  769         VNET_LIST_RUNLOCK_NOSLEEP();
  770 }
  771 
  772 /*
  773  * Drain off all datagram fragments.
  774  */
  775 void
  776 frag6_drain(void)
  777 {
  778         VNET_ITERATOR_DECL(vnet_iter);
  779 
  780         VNET_LIST_RLOCK_NOSLEEP();
  781         if (IP6Q_TRYLOCK() == 0) {
  782                 VNET_LIST_RUNLOCK_NOSLEEP();
  783                 return;
  784         }
  785         VNET_FOREACH(vnet_iter) {
  786                 CURVNET_SET(vnet_iter);
  787                 while (V_ip6q.ip6q_next != &V_ip6q) {
  788                         IP6STAT_INC(ip6s_fragdropped);
  789                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  790                         frag6_freef(V_ip6q.ip6q_next);
  791                 }
  792                 CURVNET_RESTORE();
  793         }
  794         IP6Q_UNLOCK();
  795         VNET_LIST_RUNLOCK_NOSLEEP();
  796 }
  797 
  798 int
  799 ip6_deletefraghdr(struct mbuf *m, int offset, int wait)
  800 {
  801         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  802         struct mbuf *t;
  803 
  804         /* Delete frag6 header. */
  805         if (m->m_len >= offset + sizeof(struct ip6_frag)) {
  806                 /* This is the only possible case with !PULLDOWN_TEST. */
  807                 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag),
  808                     offset);
  809                 m->m_data += sizeof(struct ip6_frag);
  810                 m->m_len -= sizeof(struct ip6_frag);
  811         } else {
  812                 /* This comes with no copy if the boundary is on cluster. */
  813                 if ((t = m_split(m, offset, wait)) == NULL)
  814                         return (ENOMEM);
  815                 m_adj(t, sizeof(struct ip6_frag));
  816                 m_cat(m, t);
  817         }
  818 
  819         return (0);
  820 }

Cache object: 30b49ce628deb3654c5b85b3d3cb9b4f


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