frag6.c

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    1 /*      $NetBSD: frag6.c,v 1.76 2022/10/21 09:21:17 ozaki-r Exp $       */
    2 /*      $KAME: frag6.c,v 1.40 2002/05/27 21:40:31 itojun Exp $  */
    3 
    4 /*
    5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __KERNEL_RCSID(0, "$NetBSD: frag6.c,v 1.76 2022/10/21 09:21:17 ozaki-r Exp $");
   35 
   36 #ifdef _KERNEL_OPT
   37 #include "opt_net_mpsafe.h"
   38 #endif
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/errno.h>
   44 #include <sys/time.h>
   45 #include <sys/kmem.h>
   46 #include <sys/kernel.h>
   47 #include <sys/syslog.h>
   48 
   49 #include <net/if.h>
   50 #include <net/route.h>
   51 
   52 #include <netinet/in.h>
   53 #include <netinet/in_var.h>
   54 #include <netinet/ip6.h>
   55 #include <netinet6/ip6_var.h>
   56 #include <netinet6/ip6_private.h>
   57 #include <netinet/icmp6.h>
   58 
   59 /*
   60  * IPv6 reassembly queue structure. Each fragment being reassembled is
   61  * attached to one of these structures.
   62  *
   63  * XXX: Would be better to use TAILQ.
   64  */
   65 struct  ip6q {
   66         u_int32_t       ip6q_head;
   67         u_int16_t       ip6q_len;
   68         u_int8_t        ip6q_nxt;       /* ip6f_nxt in first fragment */
   69         u_int8_t        ip6q_hlim;
   70         struct ip6asfrag *ip6q_down;
   71         struct ip6asfrag *ip6q_up;
   72         u_int32_t       ip6q_ident;
   73         u_int8_t        ip6q_ttl;
   74         struct in6_addr ip6q_src, ip6q_dst;
   75         struct ip6q     *ip6q_next;
   76         struct ip6q     *ip6q_prev;
   77         int             ip6q_unfrglen;  /* len of unfragmentable part */
   78         int             ip6q_nfrag;     /* # of fragments */
   79         int             ip6q_ipsec;     /* IPsec flags */
   80 };
   81 
   82 struct  ip6asfrag {
   83         u_int32_t       ip6af_head;
   84         u_int16_t       ip6af_len;
   85         u_int8_t        ip6af_nxt;
   86         u_int8_t        ip6af_hlim;
   87         /* must not override the above members during reassembling */
   88         struct ip6asfrag *ip6af_down;
   89         struct ip6asfrag *ip6af_up;
   90         struct mbuf     *ip6af_m;
   91         int             ip6af_offset;   /* offset in ip6af_m to next header */
   92         int             ip6af_frglen;   /* fragmentable part length */
   93         int             ip6af_off;      /* fragment offset */
   94         bool            ip6af_mff;      /* more fragment bit in frag off */
   95 };
   96 
   97 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
   98 static void frag6_deq(struct ip6asfrag *);
   99 static void frag6_insque(struct ip6q *, struct ip6q *);
  100 static void frag6_remque(struct ip6q *);
  101 static void frag6_freef(struct ip6q *);
  102 
  103 static int frag6_drainwanted;
  104 
  105 static u_int frag6_nfragpackets;
  106 static u_int frag6_nfrags;
  107 static struct ip6q ip6q;        /* ip6 reassembly queue */
  108 
  109 /* Protects ip6q */
  110 static kmutex_t frag6_lock __cacheline_aligned;
  111 
  112 /*
  113  * Initialise reassembly queue and fragment identifier.
  114  */
  115 void
  116 frag6_init(void)
  117 {
  118 
  119         ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
  120         mutex_init(&frag6_lock, MUTEX_DEFAULT, IPL_NONE);
  121 }
  122 
  123 /*
  124  * IPv6 fragment input.
  125  *
  126  * In RFC2460, fragment and reassembly rule do not agree with each other,
  127  * in terms of next header field handling in fragment header.
  128  * While the sender will use the same value for all of the fragmented packets,
  129  * receiver is suggested not to check the consistency.
  130  *
  131  * fragment rule (p20):
  132  *      (2) A Fragment header containing:
  133  *      The Next Header value that identifies the first header of
  134  *      the Fragmentable Part of the original packet.
  135  *              -> next header field is same for all fragments
  136  *
  137  * reassembly rule (p21):
  138  *      The Next Header field of the last header of the Unfragmentable
  139  *      Part is obtained from the Next Header field of the first
  140  *      fragment's Fragment header.
  141  *              -> should grab it from the first fragment only
  142  *
  143  * The following note also contradicts with fragment rule - noone is going to
  144  * send different fragment with different next header field.
  145  *
  146  * additional note (p22):
  147  *      The Next Header values in the Fragment headers of different
  148  *      fragments of the same original packet may differ.  Only the value
  149  *      from the Offset zero fragment packet is used for reassembly.
  150  *              -> should grab it from the first fragment only
  151  *
  152  * There is no explicit reason given in the RFC.  Historical reason maybe?
  153  *
  154  * XXX: It would be better to use a pool, rather than kmem.
  155  */
  156 int
  157 frag6_input(struct mbuf **mp, int *offp, int proto)
  158 {
  159         struct rtentry *rt;
  160         struct mbuf *m = *mp, *t;
  161         struct ip6_hdr *ip6;
  162         struct ip6_frag *ip6f;
  163         struct ip6q *q6;
  164         struct ip6asfrag *af6, *ip6af, *af6dwn;
  165         int offset = *offp, nxt, i, next;
  166         int ipsecflags = m->m_flags & (M_DECRYPTED|M_AUTHIPHDR);
  167         int first_frag = 0;
  168         int fragoff, frgpartlen;        /* must be larger than u_int16_t */
  169         struct ifnet *dstifp;
  170         static struct route ro;
  171         union {
  172                 struct sockaddr         dst;
  173                 struct sockaddr_in6     dst6;
  174         } u;
  175 
  176         ip6 = mtod(m, struct ip6_hdr *);
  177         IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
  178         if (ip6f == NULL)
  179                 return IPPROTO_DONE;
  180 
  181         dstifp = NULL;
  182         /* find the destination interface of the packet. */
  183         sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
  184         if ((rt = rtcache_lookup(&ro, &u.dst)) != NULL)
  185                 dstifp = ((struct in6_ifaddr *)rt->rt_ifa)->ia_ifp;
  186 
  187         /* jumbo payload can't contain a fragment header */
  188         if (ip6->ip6_plen == 0) {
  189                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
  190                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  191                 goto done;
  192         }
  193 
  194         /*
  195          * Check whether fragment packet's fragment length is non-zero and
  196          * multiple of 8 octets.
  197          * sizeof(struct ip6_frag) == 8
  198          * sizeof(struct ip6_hdr) = 40
  199          */
  200         if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
  201             (((ntohs(ip6->ip6_plen) - offset) == 0) ||
  202              ((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
  203                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  204                     offsetof(struct ip6_hdr, ip6_plen));
  205                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
  206                 goto done;
  207         }
  208 
  209         IP6_STATINC(IP6_STAT_FRAGMENTS);
  210         in6_ifstat_inc(dstifp, ifs6_reass_reqd);
  211 
  212         /* offset now points to data portion */
  213         offset += sizeof(struct ip6_frag);
  214 
  215         /*
  216          * RFC6946: A host that receives an IPv6 packet which includes
  217          * a Fragment Header with the "Fragment Offset" equal to 0 and
  218          * the "M" bit equal to 0 MUST process such packet in isolation
  219          * from any other packets/fragments.
  220          *
  221          * XXX: Would be better to remove this fragment header entirely,
  222          * for us not to get confused later when looking back at the
  223          * previous headers in the chain.
  224          */
  225         fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
  226         if (fragoff == 0 && !(ip6f->ip6f_offlg & IP6F_MORE_FRAG)) {
  227                 IP6_STATINC(IP6_STAT_REASSEMBLED);
  228                 in6_ifstat_inc(dstifp, ifs6_reass_ok);
  229                 *offp = offset;
  230                 rtcache_unref(rt, &ro);
  231                 return ip6f->ip6f_nxt;
  232         }
  233 
  234         mutex_enter(&frag6_lock);
  235 
  236         /*
  237          * Enforce upper bound on number of fragments.
  238          * If maxfrag is 0, never accept fragments.
  239          * If maxfrag is -1, accept all fragments without limitation.
  240          */
  241         if (ip6_maxfrags < 0)
  242                 ;
  243         else if (frag6_nfrags >= (u_int)ip6_maxfrags)
  244                 goto dropfrag;
  245 
  246         for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
  247                 if (ip6f->ip6f_ident == q6->ip6q_ident &&
  248                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
  249                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
  250                         break;
  251 
  252         if (q6 != &ip6q) {
  253                 /* All fragments must have the same IPsec flags. */
  254                 if (q6->ip6q_ipsec != ipsecflags) {
  255                         goto dropfrag;
  256                 }
  257         }
  258 
  259         if (q6 == &ip6q) {
  260                 /*
  261                  * the first fragment to arrive, create a reassembly queue.
  262                  */
  263                 first_frag = 1;
  264 
  265                 /*
  266                  * Enforce upper bound on number of fragmented packets
  267                  * for which we attempt reassembly;
  268                  * If maxfragpackets is 0, never accept fragments.
  269                  * If maxfragpackets is -1, accept all fragments without
  270                  * limitation.
  271                  */
  272                 if (ip6_maxfragpackets < 0)
  273                         ;
  274                 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
  275                         goto dropfrag;
  276                 frag6_nfragpackets++;
  277 
  278                 q6 = kmem_intr_zalloc(sizeof(struct ip6q), KM_NOSLEEP);
  279                 if (q6 == NULL) {
  280                         goto dropfrag;
  281                 }
  282                 frag6_insque(q6, &ip6q);
  283 
  284                 /* ip6q_nxt will be filled afterwards, from 1st fragment */
  285                 q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
  286                 q6->ip6q_ident  = ip6f->ip6f_ident;
  287                 q6->ip6q_ttl    = IPV6_FRAGTTL;
  288                 q6->ip6q_src    = ip6->ip6_src;
  289                 q6->ip6q_dst    = ip6->ip6_dst;
  290                 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
  291                 q6->ip6q_nfrag = 0;
  292                 q6->ip6q_ipsec = ipsecflags;
  293         }
  294 
  295         /*
  296          * If it's the 1st fragment, record the length of the
  297          * unfragmentable part and the next header of the fragment header.
  298          */
  299         if (fragoff == 0) {
  300                 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
  301                     sizeof(struct ip6_frag);
  302                 q6->ip6q_nxt = ip6f->ip6f_nxt;
  303         }
  304 
  305         /*
  306          * Check that the reassembled packet would not exceed 65535 bytes
  307          * in size. If it would exceed, discard the fragment and return an
  308          * ICMP error.
  309          */
  310         frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
  311         if (q6->ip6q_unfrglen >= 0) {
  312                 /* The 1st fragment has already arrived. */
  313                 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
  314                         mutex_exit(&frag6_lock);
  315                         icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  316                             offset - sizeof(struct ip6_frag) +
  317                             offsetof(struct ip6_frag, ip6f_offlg));
  318                         goto done;
  319                 }
  320         } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
  321                 mutex_exit(&frag6_lock);
  322                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
  323                     offset - sizeof(struct ip6_frag) +
  324                     offsetof(struct ip6_frag, ip6f_offlg));
  325                 goto done;
  326         }
  327 
  328         /*
  329          * If it's the first fragment, do the above check for each
  330          * fragment already stored in the reassembly queue.
  331          */
  332         if (fragoff == 0) {
  333                 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  334                      af6 = af6dwn) {
  335                         af6dwn = af6->ip6af_down;
  336 
  337                         if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
  338                             IPV6_MAXPACKET) {
  339                                 struct mbuf *merr = af6->ip6af_m;
  340                                 struct ip6_hdr *ip6err;
  341                                 int erroff = af6->ip6af_offset;
  342 
  343                                 /* dequeue the fragment. */
  344                                 frag6_deq(af6);
  345                                 kmem_intr_free(af6, sizeof(struct ip6asfrag));
  346 
  347                                 /* adjust pointer. */
  348                                 ip6err = mtod(merr, struct ip6_hdr *);
  349 
  350                                 /*
  351                                  * Restore source and destination addresses
  352                                  * in the erroneous IPv6 header.
  353                                  */
  354                                 ip6err->ip6_src = q6->ip6q_src;
  355                                 ip6err->ip6_dst = q6->ip6q_dst;
  356 
  357                                 icmp6_error(merr, ICMP6_PARAM_PROB,
  358                                     ICMP6_PARAMPROB_HEADER,
  359                                     erroff - sizeof(struct ip6_frag) +
  360                                     offsetof(struct ip6_frag, ip6f_offlg));
  361                         }
  362                 }
  363         }
  364 
  365         ip6af = kmem_intr_zalloc(sizeof(struct ip6asfrag), KM_NOSLEEP);
  366         if (ip6af == NULL) {
  367                 goto dropfrag;
  368         }
  369         ip6af->ip6af_head = ip6->ip6_flow;
  370         ip6af->ip6af_len = ip6->ip6_plen;
  371         ip6af->ip6af_nxt = ip6->ip6_nxt;
  372         ip6af->ip6af_hlim = ip6->ip6_hlim;
  373         ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) != 0;
  374         ip6af->ip6af_off = fragoff;
  375         ip6af->ip6af_frglen = frgpartlen;
  376         ip6af->ip6af_offset = offset;
  377         ip6af->ip6af_m = m;
  378 
  379         if (first_frag) {
  380                 af6 = (struct ip6asfrag *)q6;
  381                 goto insert;
  382         }
  383 
  384         /*
  385          * Find a segment which begins after this one does.
  386          */
  387         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  388              af6 = af6->ip6af_down)
  389                 if (af6->ip6af_off > ip6af->ip6af_off)
  390                         break;
  391 
  392         /*
  393          * If the incoming fragment overlaps some existing fragments in
  394          * the reassembly queue - drop it as per RFC 5722.
  395          */
  396         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
  397                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
  398                         - ip6af->ip6af_off;
  399                 if (i > 0) {
  400                         kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
  401                         goto dropfrag;
  402                 }
  403         }
  404         if (af6 != (struct ip6asfrag *)q6) {
  405                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
  406                 if (i > 0) {
  407                         kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
  408                         goto dropfrag;
  409                 }
  410         }
  411 
  412 insert:
  413         /*
  414          * Stick new segment in its place.
  415          */
  416         frag6_enq(ip6af, af6->ip6af_up);
  417         frag6_nfrags++;
  418         q6->ip6q_nfrag++;
  419 
  420         /*
  421          * Check for complete reassembly.
  422          */
  423         next = 0;
  424         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  425              af6 = af6->ip6af_down) {
  426                 if (af6->ip6af_off != next) {
  427                         mutex_exit(&frag6_lock);
  428                         goto done;
  429                 }
  430                 next += af6->ip6af_frglen;
  431         }
  432         if (af6->ip6af_up->ip6af_mff) {
  433                 mutex_exit(&frag6_lock);
  434                 goto done;
  435         }
  436 
  437         /*
  438          * Reassembly is complete; concatenate fragments.
  439          */
  440         ip6af = q6->ip6q_down;
  441         t = m = ip6af->ip6af_m;
  442         af6 = ip6af->ip6af_down;
  443         frag6_deq(ip6af);
  444         while (af6 != (struct ip6asfrag *)q6) {
  445                 af6dwn = af6->ip6af_down;
  446                 frag6_deq(af6);
  447                 while (t->m_next)
  448                         t = t->m_next;
  449                 t->m_next = af6->ip6af_m;
  450                 m_adj(t->m_next, af6->ip6af_offset);
  451                 m_remove_pkthdr(t->m_next);
  452                 kmem_intr_free(af6, sizeof(struct ip6asfrag));
  453                 af6 = af6dwn;
  454         }
  455 
  456         /* adjust offset to point where the original next header starts */
  457         offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
  458         kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
  459         ip6 = mtod(m, struct ip6_hdr *);
  460         ip6->ip6_plen = htons(next + offset - sizeof(struct ip6_hdr));
  461         ip6->ip6_src = q6->ip6q_src;
  462         ip6->ip6_dst = q6->ip6q_dst;
  463         nxt = q6->ip6q_nxt;
  464 
  465         /*
  466          * Delete frag6 header.
  467          */
  468         if (m->m_len >= offset + sizeof(struct ip6_frag)) {
  469                 memmove((char *)ip6 + sizeof(struct ip6_frag), ip6, offset);
  470                 m->m_data += sizeof(struct ip6_frag);
  471                 m->m_len -= sizeof(struct ip6_frag);
  472         } else {
  473                 /* this comes with no copy if the boundary is on cluster */
  474                 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
  475                         frag6_remque(q6);
  476                         frag6_nfrags -= q6->ip6q_nfrag;
  477                         kmem_intr_free(q6, sizeof(struct ip6q));
  478                         frag6_nfragpackets--;
  479                         goto dropfrag;
  480                 }
  481                 m_adj(t, sizeof(struct ip6_frag));
  482                 m_cat(m, t);
  483         }
  484 
  485         frag6_remque(q6);
  486         frag6_nfrags -= q6->ip6q_nfrag;
  487         kmem_intr_free(q6, sizeof(struct ip6q));
  488         frag6_nfragpackets--;
  489 
  490         {
  491                 KASSERT(m->m_flags & M_PKTHDR);
  492                 int plen = 0;
  493                 for (t = m; t; t = t->m_next) {
  494                         plen += t->m_len;
  495                 }
  496                 m->m_pkthdr.len = plen;
  497                 /* XXX XXX: clear csum_flags? */
  498         }
  499 
  500         /*
  501          * Restore NXT to the original.
  502          */
  503         {
  504                 const int prvnxt = ip6_get_prevhdr(m, offset);
  505                 uint8_t *prvnxtp;
  506 
  507                 IP6_EXTHDR_GET(prvnxtp, uint8_t *, m, prvnxt,
  508                     sizeof(*prvnxtp));
  509                 if (prvnxtp == NULL) {
  510                         goto dropfrag;
  511                 }
  512                 *prvnxtp = nxt;
  513         }
  514 
  515         IP6_STATINC(IP6_STAT_REASSEMBLED);
  516         in6_ifstat_inc(dstifp, ifs6_reass_ok);
  517         rtcache_unref(rt, &ro);
  518         mutex_exit(&frag6_lock);
  519 
  520         /*
  521          * Tell launch routine the next header.
  522          */
  523         *mp = m;
  524         *offp = offset;
  525         return nxt;
  526 
  527  dropfrag:
  528         mutex_exit(&frag6_lock);
  529         in6_ifstat_inc(dstifp, ifs6_reass_fail);
  530         IP6_STATINC(IP6_STAT_FRAGDROPPED);
  531         m_freem(m);
  532  done:
  533         rtcache_unref(rt, &ro);
  534         return IPPROTO_DONE;
  535 }
  536 
  537 int
  538 ip6_reass_packet(struct mbuf **mp, int offset)
  539 {
  540 
  541         if (frag6_input(mp, &offset, IPPROTO_IPV6) == IPPROTO_DONE) {
  542                 *mp = NULL;
  543                 return EINVAL;
  544         }
  545         return 0;
  546 }
  547 
  548 /*
  549  * Free a fragment reassembly header and all
  550  * associated datagrams.
  551  */
  552 static void
  553 frag6_freef(struct ip6q *q6)
  554 {
  555         struct ip6asfrag *af6, *down6;
  556 
  557         KASSERT(mutex_owned(&frag6_lock));
  558 
  559         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
  560              af6 = down6) {
  561                 struct mbuf *m = af6->ip6af_m;
  562 
  563                 down6 = af6->ip6af_down;
  564                 frag6_deq(af6);
  565 
  566                 /*
  567                  * Return ICMP time exceeded error for the 1st fragment.
  568                  * Just free other fragments.
  569                  */
  570                 if (af6->ip6af_off == 0) {
  571                         struct ip6_hdr *ip6;
  572 
  573                         /* adjust pointer */
  574                         ip6 = mtod(m, struct ip6_hdr *);
  575 
  576                         /* restore source and destination addresses */
  577                         ip6->ip6_src = q6->ip6q_src;
  578                         ip6->ip6_dst = q6->ip6q_dst;
  579 
  580                         icmp6_error(m, ICMP6_TIME_EXCEEDED,
  581                                     ICMP6_TIME_EXCEED_REASSEMBLY, 0);
  582                 } else {
  583                         m_freem(m);
  584                 }
  585                 kmem_intr_free(af6, sizeof(struct ip6asfrag));
  586         }
  587 
  588         frag6_remque(q6);
  589         frag6_nfrags -= q6->ip6q_nfrag;
  590         kmem_intr_free(q6, sizeof(struct ip6q));
  591         frag6_nfragpackets--;
  592 }
  593 
  594 /*
  595  * Put an ip fragment on a reassembly chain.
  596  * Like insque, but pointers in middle of structure.
  597  */
  598 void
  599 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
  600 {
  601 
  602         KASSERT(mutex_owned(&frag6_lock));
  603 
  604         af6->ip6af_up = up6;
  605         af6->ip6af_down = up6->ip6af_down;
  606         up6->ip6af_down->ip6af_up = af6;
  607         up6->ip6af_down = af6;
  608 }
  609 
  610 /*
  611  * To frag6_enq as remque is to insque.
  612  */
  613 void
  614 frag6_deq(struct ip6asfrag *af6)
  615 {
  616 
  617         KASSERT(mutex_owned(&frag6_lock));
  618 
  619         af6->ip6af_up->ip6af_down = af6->ip6af_down;
  620         af6->ip6af_down->ip6af_up = af6->ip6af_up;
  621 }
  622 
  623 /*
  624  * Insert newq after oldq.
  625  */
  626 void
  627 frag6_insque(struct ip6q *newq, struct ip6q *oldq)
  628 {
  629 
  630         KASSERT(mutex_owned(&frag6_lock));
  631 
  632         newq->ip6q_prev = oldq;
  633         newq->ip6q_next = oldq->ip6q_next;
  634         oldq->ip6q_next->ip6q_prev = newq;
  635         oldq->ip6q_next = newq;
  636 }
  637 
  638 /*
  639  * Unlink p6.
  640  */
  641 void
  642 frag6_remque(struct ip6q *p6)
  643 {
  644 
  645         KASSERT(mutex_owned(&frag6_lock));
  646 
  647         p6->ip6q_prev->ip6q_next = p6->ip6q_next;
  648         p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
  649 }
  650 
  651 void
  652 frag6_fasttimo(void)
  653 {
  654 
  655         SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
  656 
  657         if (frag6_drainwanted) {
  658                 frag6_drain();
  659                 frag6_drainwanted = 0;
  660         }
  661 
  662         SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
  663 }
  664 
  665 /*
  666  * IPv6 reassembling timer processing;
  667  * if a timer expires on a reassembly
  668  * queue, discard it.
  669  */
  670 void
  671 frag6_slowtimo(void)
  672 {
  673         struct ip6q *q6;
  674 
  675         SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
  676 
  677         mutex_enter(&frag6_lock);
  678         q6 = ip6q.ip6q_next;
  679         if (q6) {
  680                 while (q6 != &ip6q) {
  681                         --q6->ip6q_ttl;
  682                         q6 = q6->ip6q_next;
  683                         if (q6->ip6q_prev->ip6q_ttl == 0) {
  684                                 IP6_STATINC(IP6_STAT_FRAGTIMEOUT);
  685                                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  686                                 frag6_freef(q6->ip6q_prev);
  687                         }
  688                 }
  689         }
  690 
  691         /*
  692          * If we are over the maximum number of fragments
  693          * (due to the limit being lowered), drain off
  694          * enough to get down to the new limit.
  695          */
  696         while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
  697             ip6q.ip6q_prev) {
  698                 IP6_STATINC(IP6_STAT_FRAGOVERFLOW);
  699                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  700                 frag6_freef(ip6q.ip6q_prev);
  701         }
  702         mutex_exit(&frag6_lock);
  703 
  704         SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
  705 
  706 #if 0
  707         /*
  708          * Routing changes might produce a better route than we last used;
  709          * make sure we notice eventually, even if forwarding only for one
  710          * destination and the cache is never replaced.
  711          */
  712         rtcache_free(&ip6_forward_rt);
  713         rtcache_free(&ipsrcchk_rt);
  714 #endif
  715 }
  716 
  717 void
  718 frag6_drainstub(void)
  719 {
  720         frag6_drainwanted = 1;
  721 }
  722 
  723 /*
  724  * Drain off all datagram fragments.
  725  */
  726 void
  727 frag6_drain(void)
  728 {
  729 
  730         if (mutex_tryenter(&frag6_lock)) {
  731                 while (ip6q.ip6q_next != &ip6q) {
  732                         IP6_STATINC(IP6_STAT_FRAGDROPPED);
  733                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
  734                         frag6_freef(ip6q.ip6q_next);
  735                 }
  736                 mutex_exit(&frag6_lock);
  737         }
  738 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/frag6.c

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