1/*- 2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the project nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ 30 */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: stable/10/sys/netinet6/frag6.c 329158 2018-02-12 13:52:58Z ae $"); 34 35#include <sys/param.h> 36#include <sys/systm.h> 37#include <sys/malloc.h> 38#include <sys/mbuf.h> 39#include <sys/domain.h> 40#include <sys/protosw.h> 41#include <sys/socket.h> 42#include <sys/errno.h> 43#include <sys/time.h> 44#include <sys/kernel.h> 45#include <sys/syslog.h> 46 47#include <net/if.h> 48#include <net/route.h> 49#include <net/vnet.h> 50 51#include <netinet/in.h> 52#include <netinet/in_var.h> 53#include <netinet/ip6.h> 54#include <netinet6/ip6_var.h> 55#include <netinet/icmp6.h> 56#include <netinet/in_systm.h> /* for ECN definitions */ 57#include <netinet/ip.h> /* for ECN definitions */ 58 59#include <security/mac/mac_framework.h> 60 61/* 62 * Define it to get a correct behavior on per-interface statistics. 63 * You will need to perform an extra routing table lookup, per fragment, 64 * to do it. This may, or may not be, a performance hit. 65 */ 66#define IN6_IFSTAT_STRICT 67 68static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *); 69static void frag6_deq(struct ip6asfrag *); 70static void frag6_insque(struct ip6q *, struct ip6q *); 71static void frag6_remque(struct ip6q *); 72static void frag6_freef(struct ip6q *); 73 74static struct mtx ip6qlock; 75/* 76 * These fields all protected by ip6qlock. 77 */ 78static VNET_DEFINE(u_int, frag6_nfragpackets); 79static VNET_DEFINE(u_int, frag6_nfrags); 80static VNET_DEFINE(struct ip6q, ip6q); /* ip6 reassemble queue */ 81 82#define V_frag6_nfragpackets VNET(frag6_nfragpackets) 83#define V_frag6_nfrags VNET(frag6_nfrags) 84#define V_ip6q VNET(ip6q) 85 86#define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF); 87#define IP6Q_LOCK() mtx_lock(&ip6qlock) 88#define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock) 89#define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED) 90#define IP6Q_UNLOCK() mtx_unlock(&ip6qlock) 91 92static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header"); 93 94/* 95 * Initialise reassembly queue and fragment identifier. 96 */ 97static void 98frag6_change(void *tag) 99{ 100 101 V_ip6_maxfragpackets = nmbclusters / 4; 102 V_ip6_maxfrags = nmbclusters / 4; 103} 104 105void 106frag6_init(void) 107{ 108 109 V_ip6_maxfragpackets = nmbclusters / 4; 110 V_ip6_maxfrags = nmbclusters / 4; 111 V_ip6q.ip6q_next = V_ip6q.ip6q_prev = &V_ip6q; 112 113 if (!IS_DEFAULT_VNET(curvnet)) 114 return; 115 116 EVENTHANDLER_REGISTER(nmbclusters_change, 117 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 118 119 IP6Q_LOCK_INIT(); 120} 121 122/* 123 * In RFC2460, fragment and reassembly rule do not agree with each other, 124 * in terms of next header field handling in fragment header. 125 * While the sender will use the same value for all of the fragmented packets, 126 * receiver is suggested not to check the consistency. 127 * 128 * fragment rule (p20): 129 * (2) A Fragment header containing: 130 * The Next Header value that identifies the first header of 131 * the Fragmentable Part of the original packet. 132 * -> next header field is same for all fragments 133 * 134 * reassembly rule (p21): 135 * The Next Header field of the last header of the Unfragmentable 136 * Part is obtained from the Next Header field of the first 137 * fragment's Fragment header. 138 * -> should grab it from the first fragment only 139 * 140 * The following note also contradicts with fragment rule - noone is going to 141 * send different fragment with different next header field. 142 * 143 * additional note (p22): 144 * The Next Header values in the Fragment headers of different 145 * fragments of the same original packet may differ. Only the value 146 * from the Offset zero fragment packet is used for reassembly. 147 * -> should grab it from the first fragment only 148 * 149 * There is no explicit reason given in the RFC. Historical reason maybe? 150 */ 151/* 152 * Fragment input 153 */ 154int 155frag6_input(struct mbuf **mp, int *offp, int proto) 156{ 157 struct mbuf *m = *mp, *t; 158 struct ip6_hdr *ip6; 159 struct ip6_frag *ip6f; 160 struct ip6q *q6; 161 struct ip6asfrag *af6, *ip6af, *af6dwn; 162#ifdef IN6_IFSTAT_STRICT 163 struct in6_ifaddr *ia; 164#endif 165 int offset = *offp, nxt, i, next; 166 int first_frag = 0; 167 int fragoff, frgpartlen; /* must be larger than u_int16_t */ 168 struct ifnet *dstifp; 169 u_int8_t ecn, ecn0; 170#if 0 171 char ip6buf[INET6_ADDRSTRLEN]; 172#endif 173 174 ip6 = mtod(m, struct ip6_hdr *); 175#ifndef PULLDOWN_TEST 176 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 177 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 178#else 179 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 180 if (ip6f == NULL) 181 return (IPPROTO_DONE); 182#endif 183 184 dstifp = NULL; 185#ifdef IN6_IFSTAT_STRICT 186 /* find the destination interface of the packet. */ 187 if ((ia = ip6_getdstifaddr(m)) != NULL) { 188 dstifp = ia->ia_ifp; 189 ifa_free(&ia->ia_ifa); 190 } 191#else 192 /* we are violating the spec, this is not the destination interface */ 193 if ((m->m_flags & M_PKTHDR) != 0) 194 dstifp = m->m_pkthdr.rcvif; 195#endif 196 197 /* jumbo payload can't contain a fragment header */ 198 if (ip6->ip6_plen == 0) { 199 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 200 in6_ifstat_inc(dstifp, ifs6_reass_fail); 201 return IPPROTO_DONE; 202 } 203 204 /* 205 * check whether fragment packet's fragment length is 206 * multiple of 8 octets. 207 * sizeof(struct ip6_frag) == 8 208 * sizeof(struct ip6_hdr) = 40 209 */ 210 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 211 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 212 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 213 offsetof(struct ip6_hdr, ip6_plen)); 214 in6_ifstat_inc(dstifp, ifs6_reass_fail); 215 return IPPROTO_DONE; 216 } 217 218 IP6STAT_INC(ip6s_fragments); 219 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 220 221 /* offset now points to data portion */ 222 offset += sizeof(struct ip6_frag); 223 224 /* 225 * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0) 226 * upfront, unrelated to any reassembly. Just skip the fragment header. 227 */ 228 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 229 /* XXX-BZ we want dedicated counters for this. */ 230 IP6STAT_INC(ip6s_reassembled); 231 in6_ifstat_inc(dstifp, ifs6_reass_ok); 232 *offp = offset; 233 return (ip6f->ip6f_nxt); 234 } 235 236 IP6Q_LOCK(); 237 238 /* 239 * Enforce upper bound on number of fragments. 240 * If maxfrag is 0, never accept fragments. 241 * If maxfrag is -1, accept all fragments without limitation. 242 */ 243 if (V_ip6_maxfrags < 0) 244 ; 245 else if (V_frag6_nfrags >= (u_int)V_ip6_maxfrags) 246 goto dropfrag; 247 248 for (q6 = V_ip6q.ip6q_next; q6 != &V_ip6q; q6 = q6->ip6q_next) 249 if (ip6f->ip6f_ident == q6->ip6q_ident && 250 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 251 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 252#ifdef MAC 253 && mac_ip6q_match(m, q6) 254#endif 255 ) 256 break; 257 258 if (q6 == &V_ip6q) { 259 /* 260 * the first fragment to arrive, create a reassembly queue. 261 */ 262 first_frag = 1; 263 264 /* 265 * Enforce upper bound on number of fragmented packets 266 * for which we attempt reassembly; 267 * If maxfragpackets is 0, never accept fragments. 268 * If maxfragpackets is -1, accept all fragments without 269 * limitation. 270 */ 271 if (V_ip6_maxfragpackets < 0) 272 ; 273 else if (V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets) 274 goto dropfrag; 275 V_frag6_nfragpackets++; 276 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE, 277 M_NOWAIT); 278 if (q6 == NULL) 279 goto dropfrag; 280 bzero(q6, sizeof(*q6)); 281#ifdef MAC 282 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 283 free(q6, M_FTABLE); 284 goto dropfrag; 285 } 286 mac_ip6q_create(m, q6); 287#endif 288 frag6_insque(q6, &V_ip6q); 289 290 /* ip6q_nxt will be filled afterwards, from 1st fragment */ 291 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; 292#ifdef notyet 293 q6->ip6q_nxtp = (u_char *)nxtp; 294#endif 295 q6->ip6q_ident = ip6f->ip6f_ident; 296 q6->ip6q_ttl = IPV6_FRAGTTL; 297 q6->ip6q_src = ip6->ip6_src; 298 q6->ip6q_dst = ip6->ip6_dst; 299 q6->ip6q_ecn = 300 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 301 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 302 303 q6->ip6q_nfrag = 0; 304 } 305 306 /* 307 * If it's the 1st fragment, record the length of the 308 * unfragmentable part and the next header of the fragment header. 309 */ 310 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 311 if (fragoff == 0) { 312 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 313 sizeof(struct ip6_frag); 314 q6->ip6q_nxt = ip6f->ip6f_nxt; 315 } 316 317 /* 318 * Check that the reassembled packet would not exceed 65535 bytes 319 * in size. 320 * If it would exceed, discard the fragment and return an ICMP error. 321 */ 322 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 323 if (q6->ip6q_unfrglen >= 0) { 324 /* The 1st fragment has already arrived. */ 325 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 326 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 327 offset - sizeof(struct ip6_frag) + 328 offsetof(struct ip6_frag, ip6f_offlg)); 329 IP6Q_UNLOCK(); 330 return (IPPROTO_DONE); 331 } 332 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 333 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 334 offset - sizeof(struct ip6_frag) + 335 offsetof(struct ip6_frag, ip6f_offlg)); 336 IP6Q_UNLOCK(); 337 return (IPPROTO_DONE); 338 } 339 /* 340 * If it's the first fragment, do the above check for each 341 * fragment already stored in the reassembly queue. 342 */ 343 if (fragoff == 0) { 344 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 345 af6 = af6dwn) { 346 af6dwn = af6->ip6af_down; 347 348 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > 349 IPV6_MAXPACKET) { 350 struct mbuf *merr = IP6_REASS_MBUF(af6); 351 struct ip6_hdr *ip6err; 352 int erroff = af6->ip6af_offset; 353 354 /* dequeue the fragment. */ 355 frag6_deq(af6); 356 free(af6, M_FTABLE); 357 358 /* adjust pointer. */ 359 ip6err = mtod(merr, struct ip6_hdr *); 360 361 /* 362 * Restore source and destination addresses 363 * in the erroneous IPv6 header. 364 */ 365 ip6err->ip6_src = q6->ip6q_src; 366 ip6err->ip6_dst = q6->ip6q_dst; 367 368 icmp6_error(merr, ICMP6_PARAM_PROB, 369 ICMP6_PARAMPROB_HEADER, 370 erroff - sizeof(struct ip6_frag) + 371 offsetof(struct ip6_frag, ip6f_offlg)); 372 } 373 } 374 } 375 376 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE, 377 M_NOWAIT); 378 if (ip6af == NULL) 379 goto dropfrag; 380 bzero(ip6af, sizeof(*ip6af)); 381 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; 382 ip6af->ip6af_off = fragoff; 383 ip6af->ip6af_frglen = frgpartlen; 384 ip6af->ip6af_offset = offset; 385 IP6_REASS_MBUF(ip6af) = m; 386 387 if (first_frag) { 388 af6 = (struct ip6asfrag *)q6; 389 goto insert; 390 } 391 392 /* 393 * Handle ECN by comparing this segment with the first one; 394 * if CE is set, do not lose CE. 395 * drop if CE and not-ECT are mixed for the same packet. 396 */ 397 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 398 ecn0 = q6->ip6q_ecn; 399 if (ecn == IPTOS_ECN_CE) { 400 if (ecn0 == IPTOS_ECN_NOTECT) { 401 free(ip6af, M_FTABLE); 402 goto dropfrag; 403 } 404 if (ecn0 != IPTOS_ECN_CE) 405 q6->ip6q_ecn = IPTOS_ECN_CE; 406 } 407 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 408 free(ip6af, M_FTABLE); 409 goto dropfrag; 410 } 411 412 /* 413 * Find a segment which begins after this one does. 414 */ 415 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 416 af6 = af6->ip6af_down) 417 if (af6->ip6af_off > ip6af->ip6af_off) 418 break; 419 420#if 0 421 /* 422 * If there is a preceding segment, it may provide some of 423 * our data already. If so, drop the data from the incoming 424 * segment. If it provides all of our data, drop us. 425 */ 426 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 427 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 428 - ip6af->ip6af_off; 429 if (i > 0) { 430 if (i >= ip6af->ip6af_frglen) 431 goto dropfrag; 432 m_adj(IP6_REASS_MBUF(ip6af), i); 433 ip6af->ip6af_off += i; 434 ip6af->ip6af_frglen -= i; 435 } 436 } 437 438 /* 439 * While we overlap succeeding segments trim them or, 440 * if they are completely covered, dequeue them. 441 */ 442 while (af6 != (struct ip6asfrag *)q6 && 443 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) { 444 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 445 if (i < af6->ip6af_frglen) { 446 af6->ip6af_frglen -= i; 447 af6->ip6af_off += i; 448 m_adj(IP6_REASS_MBUF(af6), i); 449 break; 450 } 451 af6 = af6->ip6af_down; 452 m_freem(IP6_REASS_MBUF(af6->ip6af_up)); 453 frag6_deq(af6->ip6af_up); 454 } 455#else 456 /* 457 * If the incoming framgent overlaps some existing fragments in 458 * the reassembly queue, drop it, since it is dangerous to override 459 * existing fragments from a security point of view. 460 * We don't know which fragment is the bad guy - here we trust 461 * fragment that came in earlier, with no real reason. 462 * 463 * Note: due to changes after disabling this part, mbuf passed to 464 * m_adj() below now does not meet the requirement. 465 */ 466 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 467 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 468 - ip6af->ip6af_off; 469 if (i > 0) { 470#if 0 /* suppress the noisy log */ 471 log(LOG_ERR, "%d bytes of a fragment from %s " 472 "overlaps the previous fragment\n", 473 i, ip6_sprintf(ip6buf, &q6->ip6q_src)); 474#endif 475 free(ip6af, M_FTABLE); 476 goto dropfrag; 477 } 478 } 479 if (af6 != (struct ip6asfrag *)q6) { 480 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 481 if (i > 0) { 482#if 0 /* suppress the noisy log */ 483 log(LOG_ERR, "%d bytes of a fragment from %s " 484 "overlaps the succeeding fragment", 485 i, ip6_sprintf(ip6buf, &q6->ip6q_src)); 486#endif 487 free(ip6af, M_FTABLE); 488 goto dropfrag; 489 } 490 } 491#endif 492 493insert: 494#ifdef MAC 495 if (!first_frag) 496 mac_ip6q_update(m, q6); 497#endif 498 499 /* 500 * Stick new segment in its place; 501 * check for complete reassembly. 502 * Move to front of packet queue, as we are 503 * the most recently active fragmented packet. 504 */ 505 frag6_enq(ip6af, af6->ip6af_up); 506 V_frag6_nfrags++; 507 q6->ip6q_nfrag++; 508#if 0 /* xxx */ 509 if (q6 != V_ip6q.ip6q_next) { 510 frag6_remque(q6); 511 frag6_insque(q6, &V_ip6q); 512 } 513#endif 514 next = 0; 515 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 516 af6 = af6->ip6af_down) { 517 if (af6->ip6af_off != next) { 518 IP6Q_UNLOCK(); 519 return IPPROTO_DONE; 520 } 521 next += af6->ip6af_frglen; 522 } 523 if (af6->ip6af_up->ip6af_mff) { 524 IP6Q_UNLOCK(); 525 return IPPROTO_DONE; 526 } 527 528 /* 529 * Reassembly is complete; concatenate fragments. 530 */ 531 ip6af = q6->ip6q_down; 532 t = m = IP6_REASS_MBUF(ip6af); 533 af6 = ip6af->ip6af_down; 534 frag6_deq(ip6af); 535 while (af6 != (struct ip6asfrag *)q6) { 536 m->m_pkthdr.csum_flags &= 537 IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags; 538 m->m_pkthdr.csum_data += 539 IP6_REASS_MBUF(af6)->m_pkthdr.csum_data; 540 541 af6dwn = af6->ip6af_down; 542 frag6_deq(af6); 543 while (t->m_next) 544 t = t->m_next; 545 t->m_next = IP6_REASS_MBUF(af6); 546 m_adj(t->m_next, af6->ip6af_offset); 547 free(af6, M_FTABLE); 548 af6 = af6dwn; 549 } 550 551 while (m->m_pkthdr.csum_data & 0xffff0000) 552 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 553 (m->m_pkthdr.csum_data >> 16); 554 555 /* adjust offset to point where the original next header starts */ 556 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 557 free(ip6af, M_FTABLE); 558 ip6 = mtod(m, struct ip6_hdr *); 559 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr)); 560 if (q6->ip6q_ecn == IPTOS_ECN_CE) 561 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 562 nxt = q6->ip6q_nxt; 563#ifdef notyet 564 *q6->ip6q_nxtp = (u_char)(nxt & 0xff); 565#endif 566 567 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { 568 frag6_remque(q6); 569 V_frag6_nfrags -= q6->ip6q_nfrag; 570#ifdef MAC 571 mac_ip6q_destroy(q6); 572#endif 573 free(q6, M_FTABLE); 574 V_frag6_nfragpackets--; 575 576 goto dropfrag; 577 } 578 579 /* 580 * Store NXT to the original. 581 */ 582 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 583 (caddr_t)&nxt); 584 585 frag6_remque(q6); 586 V_frag6_nfrags -= q6->ip6q_nfrag; 587#ifdef MAC 588 mac_ip6q_reassemble(q6, m); 589 mac_ip6q_destroy(q6); 590#endif 591 free(q6, M_FTABLE); 592 V_frag6_nfragpackets--; 593 594 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 595 int plen = 0; 596 for (t = m; t; t = t->m_next) 597 plen += t->m_len; 598 m->m_pkthdr.len = plen; 599 } 600 601 IP6STAT_INC(ip6s_reassembled); 602 in6_ifstat_inc(dstifp, ifs6_reass_ok); 603 604 /* 605 * Tell launch routine the next header 606 */ 607 608 *mp = m; 609 *offp = offset; 610 611 IP6Q_UNLOCK(); 612 return nxt; 613 614 dropfrag: 615 IP6Q_UNLOCK(); 616 in6_ifstat_inc(dstifp, ifs6_reass_fail); 617 IP6STAT_INC(ip6s_fragdropped); 618 m_freem(m); 619 return IPPROTO_DONE; 620} 621 622/* 623 * Free a fragment reassembly header and all 624 * associated datagrams. 625 */ 626void 627frag6_freef(struct ip6q *q6) 628{ 629 struct ip6asfrag *af6, *down6; 630 631 IP6Q_LOCK_ASSERT(); 632 633 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 634 af6 = down6) { 635 struct mbuf *m = IP6_REASS_MBUF(af6); 636 637 down6 = af6->ip6af_down; 638 frag6_deq(af6); 639 640 /* 641 * Return ICMP time exceeded error for the 1st fragment. 642 * Just free other fragments. 643 */ 644 if (af6->ip6af_off == 0) { 645 struct ip6_hdr *ip6; 646 647 /* adjust pointer */ 648 ip6 = mtod(m, struct ip6_hdr *); 649 650 /* restore source and destination addresses */ 651 ip6->ip6_src = q6->ip6q_src; 652 ip6->ip6_dst = q6->ip6q_dst; 653 654 icmp6_error(m, ICMP6_TIME_EXCEEDED, 655 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 656 } else 657 m_freem(m); 658 free(af6, M_FTABLE); 659 } 660 frag6_remque(q6); 661 V_frag6_nfrags -= q6->ip6q_nfrag; 662#ifdef MAC 663 mac_ip6q_destroy(q6); 664#endif 665 free(q6, M_FTABLE); 666 V_frag6_nfragpackets--; 667} 668 669/* 670 * Put an ip fragment on a reassembly chain. 671 * Like insque, but pointers in middle of structure. 672 */ 673void 674frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6) 675{ 676 677 IP6Q_LOCK_ASSERT(); 678 679 af6->ip6af_up = up6; 680 af6->ip6af_down = up6->ip6af_down; 681 up6->ip6af_down->ip6af_up = af6; 682 up6->ip6af_down = af6; 683} 684 685/* 686 * To frag6_enq as remque is to insque. 687 */ 688void 689frag6_deq(struct ip6asfrag *af6) 690{ 691 692 IP6Q_LOCK_ASSERT(); 693 694 af6->ip6af_up->ip6af_down = af6->ip6af_down; 695 af6->ip6af_down->ip6af_up = af6->ip6af_up; 696} 697 698void 699frag6_insque(struct ip6q *new, struct ip6q *old) 700{ 701 702 IP6Q_LOCK_ASSERT(); 703 704 new->ip6q_prev = old; 705 new->ip6q_next = old->ip6q_next; 706 old->ip6q_next->ip6q_prev= new; 707 old->ip6q_next = new; 708} 709 710void 711frag6_remque(struct ip6q *p6) 712{ 713 714 IP6Q_LOCK_ASSERT(); 715 716 p6->ip6q_prev->ip6q_next = p6->ip6q_next; 717 p6->ip6q_next->ip6q_prev = p6->ip6q_prev; 718} 719 720/* 721 * IPv6 reassembling timer processing; 722 * if a timer expires on a reassembly 723 * queue, discard it. 724 */ 725void 726frag6_slowtimo(void) 727{ 728 VNET_ITERATOR_DECL(vnet_iter); 729 struct ip6q *q6; 730 731 VNET_LIST_RLOCK_NOSLEEP(); 732 IP6Q_LOCK(); 733 VNET_FOREACH(vnet_iter) { 734 CURVNET_SET(vnet_iter); 735 q6 = V_ip6q.ip6q_next; 736 if (q6) 737 while (q6 != &V_ip6q) { 738 --q6->ip6q_ttl; 739 q6 = q6->ip6q_next; 740 if (q6->ip6q_prev->ip6q_ttl == 0) { 741 IP6STAT_INC(ip6s_fragtimeout); 742 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 743 frag6_freef(q6->ip6q_prev); 744 } 745 } 746 /* 747 * If we are over the maximum number of fragments 748 * (due to the limit being lowered), drain off 749 * enough to get down to the new limit. 750 */ 751 while (V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets && 752 V_ip6q.ip6q_prev) { 753 IP6STAT_INC(ip6s_fragoverflow); 754 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 755 frag6_freef(V_ip6q.ip6q_prev); 756 } 757 CURVNET_RESTORE(); 758 } 759 IP6Q_UNLOCK(); 760 VNET_LIST_RUNLOCK_NOSLEEP(); 761} 762 763/* 764 * Drain off all datagram fragments. 765 */ 766void 767frag6_drain(void) 768{ 769 VNET_ITERATOR_DECL(vnet_iter); 770 771 VNET_LIST_RLOCK_NOSLEEP(); 772 if (IP6Q_TRYLOCK() == 0) { 773 VNET_LIST_RUNLOCK_NOSLEEP(); 774 return; 775 } 776 VNET_FOREACH(vnet_iter) { 777 CURVNET_SET(vnet_iter); 778 while (V_ip6q.ip6q_next != &V_ip6q) { 779 IP6STAT_INC(ip6s_fragdropped); 780 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 781 frag6_freef(V_ip6q.ip6q_next); 782 } 783 CURVNET_RESTORE(); 784 } 785 IP6Q_UNLOCK(); 786 VNET_LIST_RUNLOCK_NOSLEEP(); 787} 788 789int 790ip6_deletefraghdr(struct mbuf *m, int offset, int wait) 791{ 792 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 793 struct mbuf *t; 794 795 /* Delete frag6 header. */ 796 if (m->m_len >= offset + sizeof(struct ip6_frag)) { 797 /* This is the only possible case with !PULLDOWN_TEST. */ 798 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), 799 offset); 800 m->m_data += sizeof(struct ip6_frag); 801 m->m_len -= sizeof(struct ip6_frag); 802 } else { 803 /* This comes with no copy if the boundary is on cluster. */ 804 if ((t = m_split(m, offset, wait)) == NULL) 805 return (ENOMEM); 806 m_adj(t, sizeof(struct ip6_frag)); 807 m_cat(m, t); 808 } 809 810 return (0); 811} 812