1 /* $NetBSD: frag6.c,v 1.19 2002/05/28 10:11:50 itojun 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 1.19 2002/05/28 10:11:50 itojun 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/errno.h> 44 #include <sys/time.h> 45 #include <sys/kernel.h> 46 #include <sys/syslog.h> 47 48 #include <net/if.h> 49 #include <net/route.h> 50 51 #include <netinet/in.h> 52 #include <netinet/in_var.h> 53 #include <netinet/ip6.h> 54 #include <netinet6/in6_pcb.h> 55 #include <netinet6/ip6_var.h> 56 #include <netinet/icmp6.h> 57 58 #include <net/net_osdep.h> 59 60 /* 61 * Define it to get a correct behavior on per-interface statistics. 62 * You will need to perform an extra routing table lookup, per fragment, 63 * to do it. This may, or may not be, a performance hit. 64 */ 65 #define IN6_IFSTAT_STRICT 66 67 static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *)); 68 static void frag6_deq __P((struct ip6asfrag *)); 69 static void frag6_insque __P((struct ip6q *, struct ip6q *)); 70 static void frag6_remque __P((struct ip6q *)); 71 static void frag6_freef __P((struct ip6q *)); 72 73 static int ip6q_locked; 74 u_int frag6_nfragpackets; 75 u_int frag6_nfrags; 76 struct ip6q ip6q; /* ip6 reassemble queue */ 77 78 static __inline int ip6q_lock_try __P((void)); 79 static __inline void ip6q_unlock __P((void)); 80 81 static __inline int 82 ip6q_lock_try() 83 { 84 int s; 85 86 /* 87 * Use splvm() -- we're bloking things that would cause 88 * mbuf allocation. 89 */ 90 s = splvm(); 91 if (ip6q_locked) { 92 splx(s); 93 return (0); 94 } 95 ip6q_locked = 1; 96 splx(s); 97 return (1); 98 } 99 100 static __inline void 101 ip6q_unlock() 102 { 103 int s; 104 105 s = splvm(); 106 ip6q_locked = 0; 107 splx(s); 108 } 109 110 #ifdef DIAGNOSTIC 111 #define IP6Q_LOCK() \ 112 do { \ 113 if (ip6q_lock_try() == 0) { \ 114 printf("%s:%d: ip6q already locked\n", __FILE__, __LINE__); \ 115 panic("ip6q_lock"); \ 116 } \ 117 } while (0) 118 #define IP6Q_LOCK_CHECK() \ 119 do { \ 120 if (ip6q_locked == 0) { \ 121 printf("%s:%d: ip6q lock not held\n", __FILE__, __LINE__); \ 122 panic("ip6q lock check"); \ 123 } \ 124 } while (0) 125 #else 126 #define IP6Q_LOCK() (void) ip6q_lock_try() 127 #define IP6Q_LOCK_CHECK() /* nothing */ 128 #endif 129 130 #define IP6Q_UNLOCK() ip6q_unlock() 131 132 #ifndef offsetof /* XXX */ 133 #define offsetof(type, member) ((size_t)(&((type *)0)->member)) 134 #endif 135 136 /* 137 * Initialise reassembly queue and fragment identifier. 138 */ 139 void 140 frag6_init() 141 { 142 143 ip6_id = arc4random(); 144 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q; 145 } 146 147 /* 148 * In RFC2460, fragment and reassembly rule do not agree with each other, 149 * in terms of next header field handling in fragment header. 150 * While the sender will use the same value for all of the fragmented packets, 151 * receiver is suggested not to check the consistency. 152 * 153 * fragment rule (p20): 154 * (2) A Fragment header containing: 155 * The Next Header value that identifies the first header of 156 * the Fragmentable Part of the original packet. 157 * -> next header field is same for all fragments 158 * 159 * reassembly rule (p21): 160 * The Next Header field of the last header of the Unfragmentable 161 * Part is obtained from the Next Header field of the first 162 * fragment's Fragment header. 163 * -> should grab it from the first fragment only 164 * 165 * The following note also contradicts with fragment rule - noone is going to 166 * send different fragment with different next header field. 167 * 168 * additional note (p22): 169 * The Next Header values in the Fragment headers of different 170 * fragments of the same original packet may differ. Only the value 171 * from the Offset zero fragment packet is used for reassembly. 172 * -> should grab it from the first fragment only 173 * 174 * There is no explicit reason given in the RFC. Historical reason maybe? 175 */ 176 /* 177 * Fragment input 178 */ 179 int 180 frag6_input(mp, offp, proto) 181 struct mbuf **mp; 182 int *offp, proto; 183 { 184 struct mbuf *m = *mp, *t; 185 struct ip6_hdr *ip6; 186 struct ip6_frag *ip6f; 187 struct ip6q *q6; 188 struct ip6asfrag *af6, *ip6af, *af6dwn; 189 int offset = *offp, nxt, i, next; 190 int first_frag = 0; 191 int fragoff, frgpartlen; /* must be larger than u_int16_t */ 192 struct ifnet *dstifp; 193 #ifdef IN6_IFSTAT_STRICT 194 static struct route_in6 ro; 195 struct sockaddr_in6 *dst; 196 #endif 197 198 ip6 = mtod(m, struct ip6_hdr *); 199 #ifndef PULLDOWN_TEST 200 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 201 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 202 #else 203 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 204 if (ip6f == NULL) 205 return IPPROTO_DONE; 206 #endif 207 208 dstifp = NULL; 209 #ifdef IN6_IFSTAT_STRICT 210 /* find the destination interface of the packet. */ 211 dst = (struct sockaddr_in6 *)&ro.ro_dst; 212 if (ro.ro_rt 213 && ((ro.ro_rt->rt_flags & RTF_UP) == 0 214 || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) { 215 RTFREE(ro.ro_rt); 216 ro.ro_rt = (struct rtentry *)0; 217 } 218 if (ro.ro_rt == NULL) { 219 bzero(dst, sizeof(*dst)); 220 dst->sin6_family = AF_INET6; 221 dst->sin6_len = sizeof(struct sockaddr_in6); 222 dst->sin6_addr = ip6->ip6_dst; 223 } 224 rtalloc((struct route *)&ro); 225 if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL) 226 dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp; 227 #else 228 /* we are violating the spec, this is not the destination interface */ 229 if ((m->m_flags & M_PKTHDR) != 0) 230 dstifp = m->m_pkthdr.rcvif; 231 #endif 232 233 /* jumbo payload can't contain a fragment header */ 234 if (ip6->ip6_plen == 0) { 235 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 236 in6_ifstat_inc(dstifp, ifs6_reass_fail); 237 return IPPROTO_DONE; 238 } 239 240 /* 241 * check whether fragment packet's fragment length is 242 * multiple of 8 octets. 243 * sizeof(struct ip6_frag) == 8 244 * sizeof(struct ip6_hdr) = 40 245 */ 246 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 247 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 248 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 249 offsetof(struct ip6_hdr, ip6_plen)); 250 in6_ifstat_inc(dstifp, ifs6_reass_fail); 251 return IPPROTO_DONE; 252 } 253 254 ip6stat.ip6s_fragments++; 255 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 256 257 /* offset now points to data portion */ 258 offset += sizeof(struct ip6_frag); 259 260 IP6Q_LOCK(); 261 262 /* 263 * Enforce upper bound on number of fragments. 264 * If maxfrag is 0, never accept fragments. 265 * If maxfrag is -1, accept all fragments without limitation. 266 */ 267 if (ip6_maxfrags < 0) 268 ; 269 else if (frag6_nfrags >= (u_int)ip6_maxfrags) 270 goto dropfrag; 271 272 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next) 273 if (ip6f->ip6f_ident == q6->ip6q_ident && 274 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 275 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)) 276 break; 277 278 if (q6 == &ip6q) { 279 /* 280 * the first fragment to arrive, create a reassembly queue. 281 */ 282 first_frag = 1; 283 284 /* 285 * Enforce upper bound on number of fragmented packets 286 * for which we attempt reassembly; 287 * If maxfragpackets is 0, never accept fragments. 288 * If maxfragpackets is -1, accept all fragments without 289 * limitation. 290 */ 291 if (ip6_maxfragpackets < 0) 292 ; 293 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) 294 goto dropfrag; 295 frag6_nfragpackets++; 296 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE, 297 M_DONTWAIT); 298 if (q6 == NULL) 299 goto dropfrag; 300 bzero(q6, sizeof(*q6)); 301 302 frag6_insque(q6, &ip6q); 303 304 /* ip6q_nxt will be filled afterwards, from 1st fragment */ 305 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; 306 #ifdef notyet 307 q6->ip6q_nxtp = (u_char *)nxtp; 308 #endif 309 q6->ip6q_ident = ip6f->ip6f_ident; 310 q6->ip6q_arrive = 0; /* Is it used anywhere? */ 311 q6->ip6q_ttl = IPV6_FRAGTTL; 312 q6->ip6q_src = ip6->ip6_src; 313 q6->ip6q_dst = ip6->ip6_dst; 314 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 315 316 q6->ip6q_nfrag = 0; 317 } 318 319 /* 320 * If it's the 1st fragment, record the length of the 321 * unfragmentable part and the next header of the fragment header. 322 */ 323 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 324 if (fragoff == 0) { 325 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 326 sizeof(struct ip6_frag); 327 q6->ip6q_nxt = ip6f->ip6f_nxt; 328 } 329 330 /* 331 * Check that the reassembled packet would not exceed 65535 bytes 332 * in size. 333 * If it would exceed, discard the fragment and return an ICMP error. 334 */ 335 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 336 if (q6->ip6q_unfrglen >= 0) { 337 /* The 1st fragment has already arrived. */ 338 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 339 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 340 offset - sizeof(struct ip6_frag) + 341 offsetof(struct ip6_frag, ip6f_offlg)); 342 IP6Q_UNLOCK(); 343 return(IPPROTO_DONE); 344 } 345 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 346 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 347 offset - sizeof(struct ip6_frag) + 348 offsetof(struct ip6_frag, ip6f_offlg)); 349 IP6Q_UNLOCK(); 350 return(IPPROTO_DONE); 351 } 352 /* 353 * If it's the first fragment, do the above check for each 354 * fragment already stored in the reassembly queue. 355 */ 356 if (fragoff == 0) { 357 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 358 af6 = af6dwn) { 359 af6dwn = af6->ip6af_down; 360 361 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > 362 IPV6_MAXPACKET) { 363 struct mbuf *merr = IP6_REASS_MBUF(af6); 364 struct ip6_hdr *ip6err; 365 int erroff = af6->ip6af_offset; 366 367 /* dequeue the fragment. */ 368 frag6_deq(af6); 369 free(af6, M_FTABLE); 370 371 /* adjust pointer. */ 372 ip6err = mtod(merr, struct ip6_hdr *); 373 374 /* 375 * Restore source and destination addresses 376 * in the erroneous IPv6 header. 377 */ 378 ip6err->ip6_src = q6->ip6q_src; 379 ip6err->ip6_dst = q6->ip6q_dst; 380 381 icmp6_error(merr, ICMP6_PARAM_PROB, 382 ICMP6_PARAMPROB_HEADER, 383 erroff - sizeof(struct ip6_frag) + 384 offsetof(struct ip6_frag, ip6f_offlg)); 385 } 386 } 387 } 388 389 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE, 390 M_DONTWAIT); 391 if (ip6af == NULL) 392 goto dropfrag; 393 bzero(ip6af, sizeof(*ip6af)); 394 ip6af->ip6af_head = ip6->ip6_flow; 395 ip6af->ip6af_len = ip6->ip6_plen; 396 ip6af->ip6af_nxt = ip6->ip6_nxt; 397 ip6af->ip6af_hlim = ip6->ip6_hlim; 398 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; 399 ip6af->ip6af_off = fragoff; 400 ip6af->ip6af_frglen = frgpartlen; 401 ip6af->ip6af_offset = offset; 402 IP6_REASS_MBUF(ip6af) = m; 403 404 if (first_frag) { 405 af6 = (struct ip6asfrag *)q6; 406 goto insert; 407 } 408 409 /* 410 * Find a segment which begins after this one does. 411 */ 412 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 413 af6 = af6->ip6af_down) 414 if (af6->ip6af_off > ip6af->ip6af_off) 415 break; 416 417 #if 0 418 /* 419 * If there is a preceding segment, it may provide some of 420 * our data already. If so, drop the data from the incoming 421 * segment. If it provides all of our data, drop us. 422 */ 423 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 424 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 425 - ip6af->ip6af_off; 426 if (i > 0) { 427 if (i >= ip6af->ip6af_frglen) 428 goto dropfrag; 429 m_adj(IP6_REASS_MBUF(ip6af), i); 430 ip6af->ip6af_off += i; 431 ip6af->ip6af_frglen -= i; 432 } 433 } 434 435 /* 436 * While we overlap succeeding segments trim them or, 437 * if they are completely covered, dequeue them. 438 */ 439 while (af6 != (struct ip6asfrag *)q6 && 440 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) { 441 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 442 if (i < af6->ip6af_frglen) { 443 af6->ip6af_frglen -= i; 444 af6->ip6af_off += i; 445 m_adj(IP6_REASS_MBUF(af6), i); 446 break; 447 } 448 af6 = af6->ip6af_down; 449 m_freem(IP6_REASS_MBUF(af6->ip6af_up)); 450 frag6_deq(af6->ip6af_up); 451 } 452 #else 453 /* 454 * If the incoming framgent overlaps some existing fragments in 455 * the reassembly queue, drop it, since it is dangerous to override 456 * existing fragments from a security point of view. 457 * We don't know which fragment is the bad guy - here we trust 458 * fragment that came in earlier, with no real reason. 459 */ 460 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 461 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 462 - ip6af->ip6af_off; 463 if (i > 0) { 464 #if 0 /* suppress the noisy log */ 465 log(LOG_ERR, "%d bytes of a fragment from %s " 466 "overlaps the previous fragment\n", 467 i, ip6_sprintf(&q6->ip6q_src)); 468 #endif 469 free(ip6af, M_FTABLE); 470 goto dropfrag; 471 } 472 } 473 if (af6 != (struct ip6asfrag *)q6) { 474 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 475 if (i > 0) { 476 #if 0 /* suppress the noisy log */ 477 log(LOG_ERR, "%d bytes of a fragment from %s " 478 "overlaps the succeeding fragment", 479 i, ip6_sprintf(&q6->ip6q_src)); 480 #endif 481 free(ip6af, M_FTABLE); 482 goto dropfrag; 483 } 484 } 485 #endif 486 487 insert: 488 489 /* 490 * Stick new segment in its place; 491 * check for complete reassembly. 492 * Move to front of packet queue, as we are 493 * the most recently active fragmented packet. 494 */ 495 frag6_enq(ip6af, af6->ip6af_up); 496 frag6_nfrags++; 497 q6->ip6q_nfrag++; 498 #if 0 /* xxx */ 499 if (q6 != ip6q.ip6q_next) { 500 frag6_remque(q6); 501 frag6_insque(q6, &ip6q); 502 } 503 #endif 504 next = 0; 505 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 506 af6 = af6->ip6af_down) { 507 if (af6->ip6af_off != next) { 508 IP6Q_UNLOCK(); 509 return IPPROTO_DONE; 510 } 511 next += af6->ip6af_frglen; 512 } 513 if (af6->ip6af_up->ip6af_mff) { 514 IP6Q_UNLOCK(); 515 return IPPROTO_DONE; 516 } 517 518 /* 519 * Reassembly is complete; concatenate fragments. 520 */ 521 ip6af = q6->ip6q_down; 522 t = m = IP6_REASS_MBUF(ip6af); 523 af6 = ip6af->ip6af_down; 524 frag6_deq(ip6af); 525 while (af6 != (struct ip6asfrag *)q6) { 526 af6dwn = af6->ip6af_down; 527 frag6_deq(af6); 528 while (t->m_next) 529 t = t->m_next; 530 t->m_next = IP6_REASS_MBUF(af6); 531 m_adj(t->m_next, af6->ip6af_offset); 532 free(af6, M_FTABLE); 533 af6 = af6dwn; 534 } 535 536 /* adjust offset to point where the original next header starts */ 537 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 538 free(ip6af, M_FTABLE); 539 ip6 = mtod(m, struct ip6_hdr *); 540 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr)); 541 ip6->ip6_src = q6->ip6q_src; 542 ip6->ip6_dst = q6->ip6q_dst; 543 nxt = q6->ip6q_nxt; 544 #ifdef notyet 545 *q6->ip6q_nxtp = (u_char)(nxt & 0xff); 546 #endif 547 548 /* 549 * Delete frag6 header with as a few cost as possible. 550 */ 551 if (offset < m->m_len) { 552 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag), 553 offset); 554 m->m_data += sizeof(struct ip6_frag); 555 m->m_len -= sizeof(struct ip6_frag); 556 } else { 557 /* this comes with no copy if the boundary is on cluster */ 558 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) { 559 frag6_remque(q6); 560 frag6_nfrags -= q6->ip6q_nfrag; 561 free(q6, M_FTABLE); 562 frag6_nfragpackets--; 563 goto dropfrag; 564 } 565 m_adj(t, sizeof(struct ip6_frag)); 566 m_cat(m, t); 567 } 568 569 /* 570 * Store NXT to the original. 571 */ 572 { 573 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */ 574 *prvnxtp = nxt; 575 } 576 577 frag6_remque(q6); 578 frag6_nfrags -= q6->ip6q_nfrag; 579 free(q6, M_FTABLE); 580 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 ip6stat.ip6s_reassembled++; 590 in6_ifstat_inc(dstifp, ifs6_reass_ok); 591 592 /* 593 * Tell launch routine the next header 594 */ 595 596 *mp = m; 597 *offp = offset; 598 599 IP6Q_UNLOCK(); 600 return nxt; 601 602 dropfrag: 603 in6_ifstat_inc(dstifp, ifs6_reass_fail); 604 ip6stat.ip6s_fragdropped++; 605 m_freem(m); 606 IP6Q_UNLOCK(); 607 return IPPROTO_DONE; 608 } 609 610 /* 611 * Free a fragment reassembly header and all 612 * associated datagrams. 613 */ 614 void 615 frag6_freef(q6) 616 struct ip6q *q6; 617 { 618 struct ip6asfrag *af6, *down6; 619 620 IP6Q_LOCK_CHECK(); 621 622 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 623 af6 = down6) { 624 struct mbuf *m = IP6_REASS_MBUF(af6); 625 626 down6 = af6->ip6af_down; 627 frag6_deq(af6); 628 629 /* 630 * Return ICMP time exceeded error for the 1st fragment. 631 * Just free other fragments. 632 */ 633 if (af6->ip6af_off == 0) { 634 struct ip6_hdr *ip6; 635 636 /* adjust pointer */ 637 ip6 = mtod(m, struct ip6_hdr *); 638 639 /* restoure source and destination addresses */ 640 ip6->ip6_src = q6->ip6q_src; 641 ip6->ip6_dst = q6->ip6q_dst; 642 643 icmp6_error(m, ICMP6_TIME_EXCEEDED, 644 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 645 } else 646 m_freem(m); 647 free(af6, M_FTABLE); 648 } 649 frag6_remque(q6); 650 frag6_nfrags -= q6->ip6q_nfrag; 651 free(q6, M_FTABLE); 652 frag6_nfragpackets--; 653 } 654 655 /* 656 * Put an ip fragment on a reassembly chain. 657 * Like insque, but pointers in middle of structure. 658 */ 659 void 660 frag6_enq(af6, up6) 661 struct ip6asfrag *af6, *up6; 662 { 663 664 IP6Q_LOCK_CHECK(); 665 666 af6->ip6af_up = up6; 667 af6->ip6af_down = up6->ip6af_down; 668 up6->ip6af_down->ip6af_up = af6; 669 up6->ip6af_down = af6; 670 } 671 672 /* 673 * To frag6_enq as remque is to insque. 674 */ 675 void 676 frag6_deq(af6) 677 struct ip6asfrag *af6; 678 { 679 680 IP6Q_LOCK_CHECK(); 681 682 af6->ip6af_up->ip6af_down = af6->ip6af_down; 683 af6->ip6af_down->ip6af_up = af6->ip6af_up; 684 } 685 686 void 687 frag6_insque(new, old) 688 struct ip6q *new, *old; 689 { 690 691 IP6Q_LOCK_CHECK(); 692 693 new->ip6q_prev = old; 694 new->ip6q_next = old->ip6q_next; 695 old->ip6q_next->ip6q_prev= new; 696 old->ip6q_next = new; 697 } 698 699 void 700 frag6_remque(p6) 701 struct ip6q *p6; 702 { 703 704 IP6Q_LOCK_CHECK(); 705 706 p6->ip6q_prev->ip6q_next = p6->ip6q_next; 707 p6->ip6q_next->ip6q_prev = p6->ip6q_prev; 708 } 709 710 /* 711 * IPv6 reassembling timer processing; 712 * if a timer expires on a reassembly 713 * queue, discard it. 714 */ 715 void 716 frag6_slowtimo() 717 { 718 struct ip6q *q6; 719 int s = splsoftnet(); 720 721 IP6Q_LOCK(); 722 q6 = ip6q.ip6q_next; 723 if (q6) 724 while (q6 != &ip6q) { 725 --q6->ip6q_ttl; 726 q6 = q6->ip6q_next; 727 if (q6->ip6q_prev->ip6q_ttl == 0) { 728 ip6stat.ip6s_fragtimeout++; 729 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 730 frag6_freef(q6->ip6q_prev); 731 } 732 } 733 /* 734 * If we are over the maximum number of fragments 735 * (due to the limit being lowered), drain off 736 * enough to get down to the new limit. 737 */ 738 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets && 739 ip6q.ip6q_prev) { 740 ip6stat.ip6s_fragoverflow++; 741 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 742 frag6_freef(ip6q.ip6q_prev); 743 } 744 IP6Q_UNLOCK(); 745 746 #if 0 747 /* 748 * Routing changes might produce a better route than we last used; 749 * make sure we notice eventually, even if forwarding only for one 750 * destination and the cache is never replaced. 751 */ 752 if (ip6_forward_rt.ro_rt) { 753 RTFREE(ip6_forward_rt.ro_rt); 754 ip6_forward_rt.ro_rt = 0; 755 } 756 if (ipsrcchk_rt.ro_rt) { 757 RTFREE(ipsrcchk_rt.ro_rt); 758 ipsrcchk_rt.ro_rt = 0; 759 } 760 #endif 761 762 splx(s); 763 } 764 765 /* 766 * Drain off all datagram fragments. 767 */ 768 void 769 frag6_drain() 770 { 771 772 if (ip6q_lock_try() == 0) 773 return; 774 while (ip6q.ip6q_next != &ip6q) { 775 ip6stat.ip6s_fragdropped++; 776 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 777 frag6_freef(ip6q.ip6q_next); 778 } 779 IP6Q_UNLOCK(); 780 } 781