sys/netinet6/frag6.c

   1 /*      $NetBSD: frag6.c,v 1.46 2008/05/21 17:08:07 drochner 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 1.46 2008/05/21 17:08:07 drochner Exp $");
  35
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/malloc.h>
  39 #include <sys/mbuf.h>
  40 #include <sys/domain.h>
  41 #include <sys/protosw.h>
  42 #include <sys/socket.h>
  43 #include <sys/socketvar.h>
  44 #include <sys/errno.h>
  45 #include <sys/time.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 #include <net/net_osdep.h>
  60
  61 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
  62 static void frag6_deq(struct ip6asfrag *);
  63 static void frag6_insque(struct ip6q *, struct ip6q *);
  64 static void frag6_remque(struct ip6q *);
  65 static void frag6_freef(struct ip6q *);
  66
  67 static int ip6q_locked;
  68 u_int frag6_nfragpackets;
  69 u_int frag6_nfrags;
  70 struct  ip6q ip6q;      /* ip6 reassemble queue */
  71
  72 static inline int ip6q_lock_try(void);
  73 static inline void ip6q_unlock(void);
  74
  75 static inline int
  76 ip6q_lock_try(void)
  77 {
  78         int s;
  79
  80         /*
  81          * Use splvm() -- we're bloking things that would cause
  82          * mbuf allocation.
  83          */
  84         s = splvm();
  85         if (ip6q_locked) {
  86                 splx(s);
  87                 return (0);
  88         }
  89         ip6q_locked = 1;
  90         splx(s);
  91         return (1);
  92 }
  93
  94 static inline void
  95 ip6q_unlock(void)
  96 {
  97         int s;
  98
  99         s = splvm();
 100         ip6q_locked = 0;
 101         splx(s);
 102 }
 103
 104 #ifdef DIAGNOSTIC
 105 #define IP6Q_LOCK()                                                     \
 106 do {                                                                    \
 107         if (ip6q_lock_try() == 0) {                                     \
 108                 printf("%s:%d: ip6q already locked\n", __FILE__, __LINE__); \
 109                 panic("ip6q_lock");                                     \
 110         }                                                               \
 111 } while (/*CONSTCOND*/ 0)
 112 #define IP6Q_LOCK_CHECK()                                               \
 113 do {                                                                    \
 114         if (ip6q_locked == 0) {                                         \
 115                 printf("%s:%d: ip6q lock not held\n", __FILE__, __LINE__); \
 116                 panic("ip6q lock check");                               \
 117         }                                                               \
 118 } while (/*CONSTCOND*/ 0)
 119 #else
 120 #define IP6Q_LOCK()             (void) ip6q_lock_try()
 121 #define IP6Q_LOCK_CHECK()       /* nothing */
 122 #endif
 123
 124 #define IP6Q_UNLOCK()           ip6q_unlock()
 125
 126 #ifndef offsetof                /* XXX */
 127 #define offsetof(type, member)  ((size_t)(&((type *)0)->member))
 128 #endif
 129
 130 /*
 131  * Initialise reassembly queue and fragment identifier.
 132  */
 133 void
 134 frag6_init(void)
 135 {
 136
 137         ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
 138 }
 139
 140 /*
 141  * In RFC2460, fragment and reassembly rule do not agree with each other,
 142  * in terms of next header field handling in fragment header.
 143  * While the sender will use the same value for all of the fragmented packets,
 144  * receiver is suggested not to check the consistency.
 145  *
 146  * fragment rule (p20):
 147  *      (2) A Fragment header containing:
 148  *      The Next Header value that identifies the first header of
 149  *      the Fragmentable Part of the original packet.
 150  *              -> next header field is same for all fragments
 151  *
 152  * reassembly rule (p21):
 153  *      The Next Header field of the last header of the Unfragmentable
 154  *      Part is obtained from the Next Header field of the first
 155  *      fragment's Fragment header.
 156  *              -> should grab it from the first fragment only
 157  *
 158  * The following note also contradicts with fragment rule - noone is going to
 159  * send different fragment with different next header field.
 160  *
 161  * additional note (p22):
 162  *      The Next Header values in the Fragment headers of different
 163  *      fragments of the same original packet may differ.  Only the value
 164  *      from the Offset zero fragment packet is used for reassembly.
 165  *              -> should grab it from the first fragment only
 166  *
 167  * There is no explicit reason given in the RFC.  Historical reason maybe?
 168  */
 169 /*
 170  * Fragment input
 171  */
 172 int
 173 frag6_input(struct mbuf **mp, int *offp, int proto)
 174 {
 175         struct rtentry *rt;
 176         struct mbuf *m = *mp, *t;
 177         struct ip6_hdr *ip6;
 178         struct ip6_frag *ip6f;
 179         struct ip6q *q6;
 180         struct ip6asfrag *af6, *ip6af, *af6dwn;
 181         int offset = *offp, nxt, i, next;
 182         int first_frag = 0;
 183         int fragoff, frgpartlen;        /* must be larger than u_int16_t */
 184         struct ifnet *dstifp;
 185         static struct route ro;
 186         union {
 187                 struct sockaddr         dst;
 188                 struct sockaddr_in6     dst6;
 189         } u;
 190
 191         ip6 = mtod(m, struct ip6_hdr *);
 192         IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
 193         if (ip6f == NULL)
 194                 return IPPROTO_DONE;
 195
 196         dstifp = NULL;
 197         /* find the destination interface of the packet. */
 198         sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
 199         if ((rt = rtcache_lookup(&ro, &u.dst)) != NULL && rt->rt_ifa != NULL)
 200                 dstifp = ((struct in6_ifaddr *)rt->rt_ifa)->ia_ifp;
 201
 202         /* jumbo payload can't contain a fragment header */
 203         if (ip6->ip6_plen == 0) {
 204                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
 205                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
 206                 return IPPROTO_DONE;
 207         }
 208
 209         /*
 210          * check whether fragment packet's fragment length is
 211          * multiple of 8 octets.
 212          * sizeof(struct ip6_frag) == 8
 213          * sizeof(struct ip6_hdr) = 40
 214          */
 215         if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
 216             (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
 217                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
 218                     offsetof(struct ip6_hdr, ip6_plen));
 219                 in6_ifstat_inc(dstifp, ifs6_reass_fail);
 220                 return IPPROTO_DONE;
 221         }
 222
 223         IP6_STATINC(IP6_STAT_FRAGMENTS);
 224         in6_ifstat_inc(dstifp, ifs6_reass_reqd);
 225
 226         /* offset now points to data portion */
 227         offset += sizeof(struct ip6_frag);
 228
 229         IP6Q_LOCK();
 230
 231         /*
 232          * Enforce upper bound on number of fragments.
 233          * If maxfrag is 0, never accept fragments.
 234          * If maxfrag is -1, accept all fragments without limitation.
 235          */
 236         if (ip6_maxfrags < 0)
 237                 ;
 238         else if (frag6_nfrags >= (u_int)ip6_maxfrags)
 239                 goto dropfrag;
 240
 241         for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
 242                 if (ip6f->ip6f_ident == q6->ip6q_ident &&
 243                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
 244                     IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
 245                         break;
 246
 247         if (q6 == &ip6q) {
 248                 /*
 249                  * the first fragment to arrive, create a reassembly queue.
 250                  */
 251                 first_frag = 1;
 252
 253                 /*
 254                  * Enforce upper bound on number of fragmented packets
 255                  * for which we attempt reassembly;
 256                  * If maxfragpackets is 0, never accept fragments.
 257                  * If maxfragpackets is -1, accept all fragments without
 258                  * limitation.
 259                  */
 260                 if (ip6_maxfragpackets < 0)
 261                         ;
 262                 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
 263                         goto dropfrag;
 264                 frag6_nfragpackets++;
 265                 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
 266                     M_DONTWAIT);
 267                 if (q6 == NULL)
 268                         goto dropfrag;
 269                 memset(q6, 0, sizeof(*q6));
 270
 271                 frag6_insque(q6, &ip6q);
 272
 273                 /* ip6q_nxt will be filled afterwards, from 1st fragment */
 274                 q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
 275 #ifdef notyet
 276                 q6->ip6q_nxtp   = (u_char *)nxtp;
 277 #endif
 278                 q6->ip6q_ident  = ip6f->ip6f_ident;
 279                 q6->ip6q_arrive = 0; /* Is it used anywhere? */
 280                 q6->ip6q_ttl    = IPV6_FRAGTTL;
 281                 q6->ip6q_src    = ip6->ip6_src;
 282                 q6->ip6q_dst    = ip6->ip6_dst;
 283                 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
 284
 285                 q6->ip6q_nfrag = 0;
 286         }
 287
 288         /*
 289          * If it's the 1st fragment, record the length of the
 290          * unfragmentable part and the next header of the fragment header.
 291          */
 292         fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
 293         if (fragoff == 0) {
 294                 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
 295                     sizeof(struct ip6_frag);
 296                 q6->ip6q_nxt = ip6f->ip6f_nxt;
 297         }
 298
 299         /*
 300          * Check that the reassembled packet would not exceed 65535 bytes
 301          * in size.
 302          * If it would exceed, discard the fragment and return an ICMP error.
 303          */
 304         frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
 305         if (q6->ip6q_unfrglen >= 0) {
 306                 /* The 1st fragment has already arrived. */
 307                 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
 308                         icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
 309                             offset - sizeof(struct ip6_frag) +
 310                             offsetof(struct ip6_frag, ip6f_offlg));
 311                         IP6Q_UNLOCK();
 312                         return (IPPROTO_DONE);
 313                 }
 314         } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
 315                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
 316                             offset - sizeof(struct ip6_frag) +
 317                                 offsetof(struct ip6_frag, ip6f_offlg));
 318                 IP6Q_UNLOCK();
 319                 return (IPPROTO_DONE);
 320         }
 321         /*
 322          * If it's the first fragment, do the above check for each
 323          * fragment already stored in the reassembly queue.
 324          */
 325         if (fragoff == 0) {
 326                 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
 327                      af6 = af6dwn) {
 328                         af6dwn = af6->ip6af_down;
 329
 330                         if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
 331                             IPV6_MAXPACKET) {
 332                                 struct mbuf *merr = IP6_REASS_MBUF(af6);
 333                                 struct ip6_hdr *ip6err;
 334                                 int erroff = af6->ip6af_offset;
 335
 336                                 /* dequeue the fragment. */
 337                                 frag6_deq(af6);
 338                                 free(af6, M_FTABLE);
 339
 340                                 /* adjust pointer. */
 341                                 ip6err = mtod(merr, struct ip6_hdr *);
 342
 343                                 /*
 344                                  * Restore source and destination addresses
 345                                  * in the erroneous IPv6 header.
 346                                  */
 347                                 ip6err->ip6_src = q6->ip6q_src;
 348                                 ip6err->ip6_dst = q6->ip6q_dst;
 349
 350                                 icmp6_error(merr, ICMP6_PARAM_PROB,
 351                                     ICMP6_PARAMPROB_HEADER,
 352                                     erroff - sizeof(struct ip6_frag) +
 353                                     offsetof(struct ip6_frag, ip6f_offlg));
 354                         }
 355                 }
 356         }
 357
 358         ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
 359             M_DONTWAIT);
 360         if (ip6af == NULL)
 361                 goto dropfrag;
 362         memset(ip6af, 0, sizeof(*ip6af));
 363         ip6af->ip6af_head = ip6->ip6_flow;
 364         ip6af->ip6af_len = ip6->ip6_plen;
 365         ip6af->ip6af_nxt = ip6->ip6_nxt;
 366         ip6af->ip6af_hlim = ip6->ip6_hlim;
 367         ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
 368         ip6af->ip6af_off = fragoff;
 369         ip6af->ip6af_frglen = frgpartlen;
 370         ip6af->ip6af_offset = offset;
 371         IP6_REASS_MBUF(ip6af) = m;
 372
 373         if (first_frag) {
 374                 af6 = (struct ip6asfrag *)q6;
 375                 goto insert;
 376         }
 377
 378         /*
 379          * Find a segment which begins after this one does.
 380          */
 381         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
 382              af6 = af6->ip6af_down)
 383                 if (af6->ip6af_off > ip6af->ip6af_off)
 384                         break;
 385
 386 #if 0
 387         /*
 388          * If there is a preceding segment, it may provide some of
 389          * our data already.  If so, drop the data from the incoming
 390          * segment.  If it provides all of our data, drop us.
 391          */
 392         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
 393                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
 394                         - ip6af->ip6af_off;
 395                 if (i > 0) {
 396                         if (i >= ip6af->ip6af_frglen)
 397                                 goto dropfrag;
 398                         m_adj(IP6_REASS_MBUF(ip6af), i);
 399                         ip6af->ip6af_off += i;
 400                         ip6af->ip6af_frglen -= i;
 401                 }
 402         }
 403
 404         /*
 405          * While we overlap succeeding segments trim them or,
 406          * if they are completely covered, dequeue them.
 407          */
 408         while (af6 != (struct ip6asfrag *)q6 &&
 409                ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
 410                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
 411                 if (i < af6->ip6af_frglen) {
 412                         af6->ip6af_frglen -= i;
 413                         af6->ip6af_off += i;
 414                         m_adj(IP6_REASS_MBUF(af6), i);
 415                         break;
 416                 }
 417                 af6 = af6->ip6af_down;
 418                 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
 419                 frag6_deq(af6->ip6af_up);
 420         }
 421 #else
 422         /*
 423          * If the incoming framgent overlaps some existing fragments in
 424          * the reassembly queue, drop it, since it is dangerous to override
 425          * existing fragments from a security point of view.
 426          * We don't know which fragment is the bad guy - here we trust
 427          * fragment that came in earlier, with no real reason.
 428          */
 429         if (af6->ip6af_up != (struct ip6asfrag *)q6) {
 430                 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
 431                         - ip6af->ip6af_off;
 432                 if (i > 0) {
 433 #if 0                           /* suppress the noisy log */
 434                         log(LOG_ERR, "%d bytes of a fragment from %s "
 435                             "overlaps the previous fragment\n",
 436                             i, ip6_sprintf(&q6->ip6q_src));
 437 #endif
 438                         free(ip6af, M_FTABLE);
 439                         goto dropfrag;
 440                 }
 441         }
 442         if (af6 != (struct ip6asfrag *)q6) {
 443                 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
 444                 if (i > 0) {
 445 #if 0                           /* suppress the noisy log */
 446                         log(LOG_ERR, "%d bytes of a fragment from %s "
 447                             "overlaps the succeeding fragment",
 448                             i, ip6_sprintf(&q6->ip6q_src));
 449 #endif
 450                         free(ip6af, M_FTABLE);
 451                         goto dropfrag;
 452                 }
 453         }
 454 #endif
 455
 456 insert:
 457
 458         /*
 459          * Stick new segment in its place;
 460          * check for complete reassembly.
 461          * Move to front of packet queue, as we are
 462          * the most recently active fragmented packet.
 463          */
 464         frag6_enq(ip6af, af6->ip6af_up);
 465         frag6_nfrags++;
 466         q6->ip6q_nfrag++;
 467 #if 0 /* xxx */
 468         if (q6 != ip6q.ip6q_next) {
 469                 frag6_remque(q6);
 470                 frag6_insque(q6, &ip6q);
 471         }
 472 #endif
 473         next = 0;
 474         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
 475              af6 = af6->ip6af_down) {
 476                 if (af6->ip6af_off != next) {
 477                         IP6Q_UNLOCK();
 478                         return IPPROTO_DONE;
 479                 }
 480                 next += af6->ip6af_frglen;
 481         }
 482         if (af6->ip6af_up->ip6af_mff) {
 483                 IP6Q_UNLOCK();
 484                 return IPPROTO_DONE;
 485         }
 486
 487         /*
 488          * Reassembly is complete; concatenate fragments.
 489          */
 490         ip6af = q6->ip6q_down;
 491         t = m = IP6_REASS_MBUF(ip6af);
 492         af6 = ip6af->ip6af_down;
 493         frag6_deq(ip6af);
 494         while (af6 != (struct ip6asfrag *)q6) {
 495                 af6dwn = af6->ip6af_down;
 496                 frag6_deq(af6);
 497                 while (t->m_next)
 498                         t = t->m_next;
 499                 t->m_next = IP6_REASS_MBUF(af6);
 500                 m_adj(t->m_next, af6->ip6af_offset);
 501                 free(af6, M_FTABLE);
 502                 af6 = af6dwn;
 503         }
 504
 505         /* adjust offset to point where the original next header starts */
 506         offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
 507         free(ip6af, M_FTABLE);
 508         ip6 = mtod(m, struct ip6_hdr *);
 509         ip6->ip6_plen = htons(next + offset - sizeof(struct ip6_hdr));
 510         ip6->ip6_src = q6->ip6q_src;
 511         ip6->ip6_dst = q6->ip6q_dst;
 512         nxt = q6->ip6q_nxt;
 513 #ifdef notyet
 514         *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
 515 #endif
 516
 517         /*
 518          * Delete frag6 header with as a few cost as possible.
 519          */
 520         if (offset < m->m_len) {
 521                 memmove((char *)ip6 + sizeof(struct ip6_frag), ip6, offset);
 522                 m->m_data += sizeof(struct ip6_frag);
 523                 m->m_len -= sizeof(struct ip6_frag);
 524         } else {
 525                 /* this comes with no copy if the boundary is on cluster */
 526                 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
 527                         frag6_remque(q6);
 528                         frag6_nfrags -= q6->ip6q_nfrag;
 529                         free(q6, M_FTABLE);
 530                         frag6_nfragpackets--;
 531                         goto dropfrag;
 532                 }
 533                 m_adj(t, sizeof(struct ip6_frag));
 534                 m_cat(m, t);
 535         }
 536
 537         /*
 538          * Store NXT to the original.
 539          */
 540         {
 541                 u_int8_t *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
 542                 *prvnxtp = nxt;
 543         }
 544
 545         frag6_remque(q6);
 546         frag6_nfrags -= q6->ip6q_nfrag;
 547         free(q6, M_FTABLE);
 548         frag6_nfragpackets--;
 549
 550         if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
 551                 int plen = 0;
 552                 for (t = m; t; t = t->m_next)
 553                         plen += t->m_len;
 554                 m->m_pkthdr.len = plen;
 555         }
 556
 557         IP6_STATINC(IP6_STAT_REASSEMBLED);
 558         in6_ifstat_inc(dstifp, ifs6_reass_ok);
 559
 560         /*
 561          * Tell launch routine the next header
 562          */
 563
 564         *mp = m;
 565         *offp = offset;
 566
 567         IP6Q_UNLOCK();
 568         return nxt;
 569
 570  dropfrag:
 571         in6_ifstat_inc(dstifp, ifs6_reass_fail);
 572         IP6_STATINC(IP6_STAT_FRAGDROPPED);
 573         m_freem(m);
 574         IP6Q_UNLOCK();
 575         return IPPROTO_DONE;
 576 }
 577
 578 /*
 579  * Free a fragment reassembly header and all
 580  * associated datagrams.
 581  */
 582 void
 583 frag6_freef(struct ip6q *q6)
 584 {
 585         struct ip6asfrag *af6, *down6;
 586
 587         IP6Q_LOCK_CHECK();
 588
 589         for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
 590              af6 = down6) {
 591                 struct mbuf *m = IP6_REASS_MBUF(af6);
 592
 593                 down6 = af6->ip6af_down;
 594                 frag6_deq(af6);
 595
 596                 /*
 597                  * Return ICMP time exceeded error for the 1st fragment.
 598                  * Just free other fragments.
 599                  */
 600                 if (af6->ip6af_off == 0) {
 601                         struct ip6_hdr *ip6;
 602
 603                         /* adjust pointer */
 604                         ip6 = mtod(m, struct ip6_hdr *);
 605
 606                         /* restoure source and destination addresses */
 607                         ip6->ip6_src = q6->ip6q_src;
 608                         ip6->ip6_dst = q6->ip6q_dst;
 609
 610                         icmp6_error(m, ICMP6_TIME_EXCEEDED,
 611                                     ICMP6_TIME_EXCEED_REASSEMBLY, 0);
 612                 } else
 613                         m_freem(m);
 614                 free(af6, M_FTABLE);
 615         }
 616         frag6_remque(q6);
 617         frag6_nfrags -= q6->ip6q_nfrag;
 618         free(q6, M_FTABLE);
 619         frag6_nfragpackets--;
 620 }
 621
 622 /*
 623  * Put an ip fragment on a reassembly chain.
 624  * Like insque, but pointers in middle of structure.
 625  */
 626 void
 627 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
 628 {
 629
 630         IP6Q_LOCK_CHECK();
 631
 632         af6->ip6af_up = up6;
 633         af6->ip6af_down = up6->ip6af_down;
 634         up6->ip6af_down->ip6af_up = af6;
 635         up6->ip6af_down = af6;
 636 }
 637
 638 /*
 639  * To frag6_enq as remque is to insque.
 640  */
 641 void
 642 frag6_deq(struct ip6asfrag *af6)
 643 {
 644
 645         IP6Q_LOCK_CHECK();
 646
 647         af6->ip6af_up->ip6af_down = af6->ip6af_down;
 648         af6->ip6af_down->ip6af_up = af6->ip6af_up;
 649 }
 650
 651 void
 652 frag6_insque(struct ip6q *new, struct ip6q *old)
 653 {
 654
 655         IP6Q_LOCK_CHECK();
 656
 657         new->ip6q_prev = old;
 658         new->ip6q_next = old->ip6q_next;
 659         old->ip6q_next->ip6q_prev= new;
 660         old->ip6q_next = new;
 661 }
 662
 663 void
 664 frag6_remque(struct ip6q *p6)
 665 {
 666
 667         IP6Q_LOCK_CHECK();
 668
 669         p6->ip6q_prev->ip6q_next = p6->ip6q_next;
 670         p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
 671 }
 672
 673 /*
 674  * IPv6 reassembling timer processing;
 675  * if a timer expires on a reassembly
 676  * queue, discard it.
 677  */
 678 void
 679 frag6_slowtimo(void)
 680 {
 681         struct ip6q *q6;
 682
 683         mutex_enter(softnet_lock);
 684         KERNEL_LOCK(1, NULL);
 685
 686         IP6Q_LOCK();
 687         q6 = ip6q.ip6q_next;
 688         if (q6)
 689                 while (q6 != &ip6q) {
 690                         --q6->ip6q_ttl;
 691                         q6 = q6->ip6q_next;
 692                         if (q6->ip6q_prev->ip6q_ttl == 0) {
 693                                 IP6_STATINC(IP6_STAT_FRAGTIMEOUT);
 694                                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
 695                                 frag6_freef(q6->ip6q_prev);
 696                         }
 697                 }
 698         /*
 699          * If we are over the maximum number of fragments
 700          * (due to the limit being lowered), drain off
 701          * enough to get down to the new limit.
 702          */
 703         while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
 704             ip6q.ip6q_prev) {
 705                 IP6_STATINC(IP6_STAT_FRAGOVERFLOW);
 706                 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
 707                 frag6_freef(ip6q.ip6q_prev);
 708         }
 709         IP6Q_UNLOCK();
 710
 711 #if 0
 712         /*
 713          * Routing changes might produce a better route than we last used;
 714          * make sure we notice eventually, even if forwarding only for one
 715          * destination and the cache is never replaced.
 716          */
 717         rtcache_free(&ip6_forward_rt);
 718         rtcache_free(&ipsrcchk_rt);
 719 #endif
 720
 721         KERNEL_UNLOCK_ONE(NULL);
 722         mutex_exit(softnet_lock);
 723 }
 724
 725 /*
 726  * Drain off all datagram fragments.
 727  */
 728 void
 729 frag6_drain(void)
 730 {
 731
 732         KERNEL_LOCK(1, NULL);
 733         if (ip6q_lock_try() != 0) {
 734                 while (ip6q.ip6q_next != &ip6q) {
 735                         IP6_STATINC(IP6_STAT_FRAGDROPPED);
 736                         /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
 737                         frag6_freef(ip6q.ip6q_next);
 738                 }
 739                 IP6Q_UNLOCK();
 740         }
 741         KERNEL_UNLOCK_ONE(NULL);
 742 }