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sys/netinet6/frag6.c
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1 /*- 2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the project nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_rss.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/hash.h> 40 #include <sys/malloc.h> 41 #include <sys/mbuf.h> 42 #include <sys/domain.h> 43 #include <sys/eventhandler.h> 44 #include <sys/protosw.h> 45 #include <sys/socket.h> 46 #include <sys/errno.h> 47 #include <sys/time.h> 48 #include <sys/kernel.h> 49 #include <sys/syslog.h> 50 51 #include <machine/atomic.h> 52 53 #include <net/if.h> 54 #include <net/if_var.h> 55 #include <net/netisr.h> 56 #include <net/route.h> 57 #include <net/vnet.h> 58 59 #include <netinet/in.h> 60 #include <netinet/in_var.h> 61 #include <netinet/ip6.h> 62 #include <netinet6/ip6_var.h> 63 #include <netinet/icmp6.h> 64 #include <netinet/in_systm.h> /* for ECN definitions */ 65 #include <netinet/ip.h> /* for ECN definitions */ 66 67 #include <security/mac/mac_framework.h> 68 69 /* 70 * Reassembly headers are stored in hash buckets. 71 */ 72 #define IP6REASS_NHASH_LOG2 10 73 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2) 74 #define IP6REASS_HMASK (IP6REASS_NHASH - 1) 75 76 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *, 77 uint32_t bucket __unused); 78 static void frag6_deq(struct ip6asfrag *, uint32_t bucket __unused); 79 static void frag6_insque_head(struct ip6q *, struct ip6q *, 80 uint32_t bucket); 81 static void frag6_remque(struct ip6q *, uint32_t bucket); 82 static void frag6_freef(struct ip6q *, uint32_t bucket); 83 84 struct ip6qbucket { 85 struct ip6q ip6q; 86 struct mtx lock; 87 int count; 88 }; 89 90 static VNET_DEFINE(volatile u_int, frag6_nfragpackets); 91 volatile u_int frag6_nfrags = 0; 92 static VNET_DEFINE(struct ip6qbucket, ip6q[IP6REASS_NHASH]); 93 static VNET_DEFINE(uint32_t, ip6q_hashseed); 94 95 #define V_frag6_nfragpackets VNET(frag6_nfragpackets) 96 #define V_ip6q VNET(ip6q) 97 #define V_ip6q_hashseed VNET(ip6q_hashseed) 98 99 #define IP6Q_LOCK(i) mtx_lock(&V_ip6q[(i)].lock) 100 #define IP6Q_TRYLOCK(i) mtx_trylock(&V_ip6q[(i)].lock) 101 #define IP6Q_LOCK_ASSERT(i) mtx_assert(&V_ip6q[(i)].lock, MA_OWNED) 102 #define IP6Q_UNLOCK(i) mtx_unlock(&V_ip6q[(i)].lock) 103 #define IP6Q_HEAD(i) (&V_ip6q[(i)].ip6q) 104 105 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header"); 106 107 /* 108 * By default, limit the number of IP6 fragments across all reassembly 109 * queues to 1/32 of the total number of mbuf clusters. 110 * 111 * Limit the total number of reassembly queues per VNET to the 112 * IP6 fragment limit, but ensure the limit will not allow any bucket 113 * to grow above 100 items. (The bucket limit is 114 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct 115 * multiplier to reach a 100-item limit.) 116 * The 100-item limit was chosen as brief testing seems to show that 117 * this produces "reasonable" performance on some subset of systems 118 * under DoS attack. 119 */ 120 #define IP6_MAXFRAGS (nmbclusters / 32) 121 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) 122 123 /* 124 * Initialise reassembly queue and fragment identifier. 125 */ 126 void 127 frag6_set_bucketsize() 128 { 129 int i; 130 131 if ((i = V_ip6_maxfragpackets) > 0) 132 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); 133 } 134 135 static void 136 frag6_change(void *tag) 137 { 138 VNET_ITERATOR_DECL(vnet_iter); 139 140 ip6_maxfrags = IP6_MAXFRAGS; 141 VNET_LIST_RLOCK_NOSLEEP(); 142 VNET_FOREACH(vnet_iter) { 143 CURVNET_SET(vnet_iter); 144 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 145 frag6_set_bucketsize(); 146 CURVNET_RESTORE(); 147 } 148 VNET_LIST_RUNLOCK_NOSLEEP(); 149 } 150 151 void 152 frag6_init(void) 153 { 154 struct ip6q *q6; 155 int i; 156 157 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 158 frag6_set_bucketsize(); 159 for (i = 0; i < IP6REASS_NHASH; i++) { 160 q6 = IP6Q_HEAD(i); 161 q6->ip6q_next = q6->ip6q_prev = q6; 162 mtx_init(&V_ip6q[i].lock, "ip6qlock", NULL, MTX_DEF); 163 V_ip6q[i].count = 0; 164 } 165 V_ip6q_hashseed = arc4random(); 166 V_ip6_maxfragsperpacket = 64; 167 if (!IS_DEFAULT_VNET(curvnet)) 168 return; 169 170 ip6_maxfrags = IP6_MAXFRAGS; 171 EVENTHANDLER_REGISTER(nmbclusters_change, 172 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 173 } 174 175 /* 176 * In RFC2460, fragment and reassembly rule do not agree with each other, 177 * in terms of next header field handling in fragment header. 178 * While the sender will use the same value for all of the fragmented packets, 179 * receiver is suggested not to check the consistency. 180 * 181 * fragment rule (p20): 182 * (2) A Fragment header containing: 183 * The Next Header value that identifies the first header of 184 * the Fragmentable Part of the original packet. 185 * -> next header field is same for all fragments 186 * 187 * reassembly rule (p21): 188 * The Next Header field of the last header of the Unfragmentable 189 * Part is obtained from the Next Header field of the first 190 * fragment's Fragment header. 191 * -> should grab it from the first fragment only 192 * 193 * The following note also contradicts with fragment rule - no one is going to 194 * send different fragment with different next header field. 195 * 196 * additional note (p22): 197 * The Next Header values in the Fragment headers of different 198 * fragments of the same original packet may differ. Only the value 199 * from the Offset zero fragment packet is used for reassembly. 200 * -> should grab it from the first fragment only 201 * 202 * There is no explicit reason given in the RFC. Historical reason maybe? 203 */ 204 /* 205 * Fragment input 206 */ 207 int 208 frag6_input(struct mbuf **mp, int *offp, int proto) 209 { 210 struct mbuf *m = *mp, *t; 211 struct ip6_hdr *ip6; 212 struct ip6_frag *ip6f; 213 struct ip6q *head, *q6; 214 struct ip6asfrag *af6, *ip6af, *af6dwn; 215 struct in6_ifaddr *ia; 216 int offset = *offp, nxt, i, next; 217 int first_frag = 0; 218 int fragoff, frgpartlen; /* must be larger than u_int16_t */ 219 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 220 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 221 uint32_t hash, *hashkeyp; 222 struct ifnet *dstifp; 223 u_int8_t ecn, ecn0; 224 #ifdef RSS 225 struct m_tag *mtag; 226 struct ip6_direct_ctx *ip6dc; 227 #endif 228 229 #if 0 230 char ip6buf[INET6_ADDRSTRLEN]; 231 #endif 232 233 ip6 = mtod(m, struct ip6_hdr *); 234 #ifndef PULLDOWN_TEST 235 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 236 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 237 #else 238 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 239 if (ip6f == NULL) 240 return (IPPROTO_DONE); 241 #endif 242 243 dstifp = NULL; 244 /* find the destination interface of the packet. */ 245 ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 246 if (ia != NULL) { 247 dstifp = ia->ia_ifp; 248 ifa_free(&ia->ia_ifa); 249 } 250 /* jumbo payload can't contain a fragment header */ 251 if (ip6->ip6_plen == 0) { 252 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 253 in6_ifstat_inc(dstifp, ifs6_reass_fail); 254 return IPPROTO_DONE; 255 } 256 257 /* 258 * check whether fragment packet's fragment length is 259 * multiple of 8 octets. 260 * sizeof(struct ip6_frag) == 8 261 * sizeof(struct ip6_hdr) = 40 262 */ 263 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 264 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 265 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 266 offsetof(struct ip6_hdr, ip6_plen)); 267 in6_ifstat_inc(dstifp, ifs6_reass_fail); 268 return IPPROTO_DONE; 269 } 270 271 IP6STAT_INC(ip6s_fragments); 272 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 273 274 /* offset now points to data portion */ 275 offset += sizeof(struct ip6_frag); 276 277 /* 278 * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0) 279 * upfront, unrelated to any reassembly. Just skip the fragment header. 280 */ 281 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 282 /* XXX-BZ we want dedicated counters for this. */ 283 IP6STAT_INC(ip6s_reassembled); 284 in6_ifstat_inc(dstifp, ifs6_reass_ok); 285 *offp = offset; 286 m->m_flags |= M_FRAGMENTED; 287 return (ip6f->ip6f_nxt); 288 } 289 290 /* Get fragment length and discard 0-byte fragments. */ 291 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 292 if (frgpartlen == 0) { 293 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 294 offsetof(struct ip6_hdr, ip6_plen)); 295 in6_ifstat_inc(dstifp, ifs6_reass_fail); 296 IP6STAT_INC(ip6s_fragdropped); 297 return IPPROTO_DONE; 298 } 299 300 hashkeyp = hashkey; 301 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 302 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 303 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 304 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 305 *hashkeyp = ip6f->ip6f_ident; 306 hash = jenkins_hash32(hashkey, nitems(hashkey), V_ip6q_hashseed); 307 hash &= IP6REASS_HMASK; 308 head = IP6Q_HEAD(hash); 309 IP6Q_LOCK(hash); 310 311 /* 312 * Enforce upper bound on number of fragments. 313 * If maxfrag is 0, never accept fragments. 314 * If maxfrag is -1, accept all fragments without limitation. 315 */ 316 if (ip6_maxfrags < 0) 317 ; 318 else if (frag6_nfrags >= (u_int)ip6_maxfrags) 319 goto dropfrag; 320 321 for (q6 = head->ip6q_next; q6 != head; q6 = q6->ip6q_next) 322 if (ip6f->ip6f_ident == q6->ip6q_ident && 323 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 324 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 325 #ifdef MAC 326 && mac_ip6q_match(m, q6) 327 #endif 328 ) 329 break; 330 331 if (q6 == head) { 332 /* 333 * the first fragment to arrive, create a reassembly queue. 334 */ 335 first_frag = 1; 336 337 /* 338 * Enforce upper bound on number of fragmented packets 339 * for which we attempt reassembly; 340 * If maxfragpackets is 0, never accept fragments. 341 * If maxfragpackets is -1, accept all fragments without 342 * limitation. 343 */ 344 if (V_ip6_maxfragpackets < 0) 345 ; 346 else if (V_ip6q[hash].count >= V_ip6_maxfragbucketsize || 347 V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets) 348 goto dropfrag; 349 atomic_add_int(&V_frag6_nfragpackets, 1); 350 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE, 351 M_NOWAIT); 352 if (q6 == NULL) 353 goto dropfrag; 354 bzero(q6, sizeof(*q6)); 355 #ifdef MAC 356 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 357 free(q6, M_FTABLE); 358 goto dropfrag; 359 } 360 mac_ip6q_create(m, q6); 361 #endif 362 frag6_insque_head(q6, head, hash); 363 364 /* ip6q_nxt will be filled afterwards, from 1st fragment */ 365 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; 366 #ifdef notyet 367 q6->ip6q_nxtp = (u_char *)nxtp; 368 #endif 369 q6->ip6q_ident = ip6f->ip6f_ident; 370 q6->ip6q_ttl = IPV6_FRAGTTL; 371 q6->ip6q_src = ip6->ip6_src; 372 q6->ip6q_dst = ip6->ip6_dst; 373 q6->ip6q_ecn = 374 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 375 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 376 377 q6->ip6q_nfrag = 0; 378 } 379 380 /* 381 * If it's the 1st fragment, record the length of the 382 * unfragmentable part and the next header of the fragment header. 383 */ 384 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 385 if (fragoff == 0) { 386 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 387 sizeof(struct ip6_frag); 388 q6->ip6q_nxt = ip6f->ip6f_nxt; 389 } 390 391 /* 392 * Check that the reassembled packet would not exceed 65535 bytes 393 * in size. 394 * If it would exceed, discard the fragment and return an ICMP error. 395 */ 396 if (q6->ip6q_unfrglen >= 0) { 397 /* The 1st fragment has already arrived. */ 398 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 399 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 400 offset - sizeof(struct ip6_frag) + 401 offsetof(struct ip6_frag, ip6f_offlg)); 402 IP6Q_UNLOCK(hash); 403 return (IPPROTO_DONE); 404 } 405 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 406 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 407 offset - sizeof(struct ip6_frag) + 408 offsetof(struct ip6_frag, ip6f_offlg)); 409 IP6Q_UNLOCK(hash); 410 return (IPPROTO_DONE); 411 } 412 /* 413 * If it's the first fragment, do the above check for each 414 * fragment already stored in the reassembly queue. 415 */ 416 if (fragoff == 0) { 417 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 418 af6 = af6dwn) { 419 af6dwn = af6->ip6af_down; 420 421 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > 422 IPV6_MAXPACKET) { 423 struct mbuf *merr = IP6_REASS_MBUF(af6); 424 struct ip6_hdr *ip6err; 425 int erroff = af6->ip6af_offset; 426 427 /* dequeue the fragment. */ 428 frag6_deq(af6, hash); 429 free(af6, M_FTABLE); 430 431 /* adjust pointer. */ 432 ip6err = mtod(merr, struct ip6_hdr *); 433 434 /* 435 * Restore source and destination addresses 436 * in the erroneous IPv6 header. 437 */ 438 ip6err->ip6_src = q6->ip6q_src; 439 ip6err->ip6_dst = q6->ip6q_dst; 440 441 icmp6_error(merr, ICMP6_PARAM_PROB, 442 ICMP6_PARAMPROB_HEADER, 443 erroff - sizeof(struct ip6_frag) + 444 offsetof(struct ip6_frag, ip6f_offlg)); 445 } 446 } 447 } 448 449 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE, 450 M_NOWAIT); 451 if (ip6af == NULL) 452 goto dropfrag; 453 bzero(ip6af, sizeof(*ip6af)); 454 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; 455 ip6af->ip6af_off = fragoff; 456 ip6af->ip6af_frglen = frgpartlen; 457 ip6af->ip6af_offset = offset; 458 IP6_REASS_MBUF(ip6af) = m; 459 460 if (first_frag) { 461 af6 = (struct ip6asfrag *)q6; 462 goto insert; 463 } 464 465 /* 466 * Handle ECN by comparing this segment with the first one; 467 * if CE is set, do not lose CE. 468 * drop if CE and not-ECT are mixed for the same packet. 469 */ 470 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 471 ecn0 = q6->ip6q_ecn; 472 if (ecn == IPTOS_ECN_CE) { 473 if (ecn0 == IPTOS_ECN_NOTECT) { 474 free(ip6af, M_FTABLE); 475 goto dropfrag; 476 } 477 if (ecn0 != IPTOS_ECN_CE) 478 q6->ip6q_ecn = IPTOS_ECN_CE; 479 } 480 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 481 free(ip6af, M_FTABLE); 482 goto dropfrag; 483 } 484 485 /* 486 * Find a segment which begins after this one does. 487 */ 488 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 489 af6 = af6->ip6af_down) 490 if (af6->ip6af_off > ip6af->ip6af_off) 491 break; 492 493 #if 0 494 /* 495 * If there is a preceding segment, it may provide some of 496 * our data already. If so, drop the data from the incoming 497 * segment. If it provides all of our data, drop us. 498 */ 499 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 500 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 501 - ip6af->ip6af_off; 502 if (i > 0) { 503 if (i >= ip6af->ip6af_frglen) 504 goto dropfrag; 505 m_adj(IP6_REASS_MBUF(ip6af), i); 506 ip6af->ip6af_off += i; 507 ip6af->ip6af_frglen -= i; 508 } 509 } 510 511 /* 512 * While we overlap succeeding segments trim them or, 513 * if they are completely covered, dequeue them. 514 */ 515 while (af6 != (struct ip6asfrag *)q6 && 516 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) { 517 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 518 if (i < af6->ip6af_frglen) { 519 af6->ip6af_frglen -= i; 520 af6->ip6af_off += i; 521 m_adj(IP6_REASS_MBUF(af6), i); 522 break; 523 } 524 af6 = af6->ip6af_down; 525 m_freem(IP6_REASS_MBUF(af6->ip6af_up)); 526 frag6_deq(af6->ip6af_up, hash); 527 } 528 #else 529 /* 530 * If the incoming framgent overlaps some existing fragments in 531 * the reassembly queue, drop it, since it is dangerous to override 532 * existing fragments from a security point of view. 533 * We don't know which fragment is the bad guy - here we trust 534 * fragment that came in earlier, with no real reason. 535 * 536 * Note: due to changes after disabling this part, mbuf passed to 537 * m_adj() below now does not meet the requirement. 538 */ 539 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 540 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen 541 - ip6af->ip6af_off; 542 if (i > 0) { 543 #if 0 /* suppress the noisy log */ 544 log(LOG_ERR, "%d bytes of a fragment from %s " 545 "overlaps the previous fragment\n", 546 i, ip6_sprintf(ip6buf, &q6->ip6q_src)); 547 #endif 548 free(ip6af, M_FTABLE); 549 goto dropfrag; 550 } 551 } 552 if (af6 != (struct ip6asfrag *)q6) { 553 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; 554 if (i > 0) { 555 #if 0 /* suppress the noisy log */ 556 log(LOG_ERR, "%d bytes of a fragment from %s " 557 "overlaps the succeeding fragment", 558 i, ip6_sprintf(ip6buf, &q6->ip6q_src)); 559 #endif 560 free(ip6af, M_FTABLE); 561 goto dropfrag; 562 } 563 } 564 #endif 565 566 insert: 567 #ifdef MAC 568 if (!first_frag) 569 mac_ip6q_update(m, q6); 570 #endif 571 572 /* 573 * Stick new segment in its place; 574 * check for complete reassembly. 575 * If not complete, check fragment limit. 576 * Move to front of packet queue, as we are 577 * the most recently active fragmented packet. 578 */ 579 frag6_enq(ip6af, af6->ip6af_up, hash); 580 atomic_add_int(&frag6_nfrags, 1); 581 q6->ip6q_nfrag++; 582 #if 0 /* xxx */ 583 if (q6 != head->ip6q_next) { 584 frag6_remque(q6, hash); 585 frag6_insque_head(q6, head, hash); 586 } 587 #endif 588 next = 0; 589 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 590 af6 = af6->ip6af_down) { 591 if (af6->ip6af_off != next) { 592 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 593 IP6STAT_INC(ip6s_fragdropped); 594 frag6_freef(q6, hash); 595 } 596 IP6Q_UNLOCK(hash); 597 return IPPROTO_DONE; 598 } 599 next += af6->ip6af_frglen; 600 } 601 if (af6->ip6af_up->ip6af_mff) { 602 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 603 IP6STAT_INC(ip6s_fragdropped); 604 frag6_freef(q6, hash); 605 } 606 IP6Q_UNLOCK(hash); 607 return IPPROTO_DONE; 608 } 609 610 /* 611 * Reassembly is complete; concatenate fragments. 612 */ 613 ip6af = q6->ip6q_down; 614 t = m = IP6_REASS_MBUF(ip6af); 615 af6 = ip6af->ip6af_down; 616 frag6_deq(ip6af, hash); 617 while (af6 != (struct ip6asfrag *)q6) { 618 m->m_pkthdr.csum_flags &= 619 IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags; 620 m->m_pkthdr.csum_data += 621 IP6_REASS_MBUF(af6)->m_pkthdr.csum_data; 622 623 af6dwn = af6->ip6af_down; 624 frag6_deq(af6, hash); 625 while (t->m_next) 626 t = t->m_next; 627 m_adj(IP6_REASS_MBUF(af6), af6->ip6af_offset); 628 m_demote_pkthdr(IP6_REASS_MBUF(af6)); 629 m_cat(t, IP6_REASS_MBUF(af6)); 630 free(af6, M_FTABLE); 631 af6 = af6dwn; 632 } 633 634 while (m->m_pkthdr.csum_data & 0xffff0000) 635 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 636 (m->m_pkthdr.csum_data >> 16); 637 638 /* adjust offset to point where the original next header starts */ 639 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 640 free(ip6af, M_FTABLE); 641 ip6 = mtod(m, struct ip6_hdr *); 642 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr)); 643 if (q6->ip6q_ecn == IPTOS_ECN_CE) 644 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 645 nxt = q6->ip6q_nxt; 646 #ifdef notyet 647 *q6->ip6q_nxtp = (u_char)(nxt & 0xff); 648 #endif 649 650 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { 651 frag6_remque(q6, hash); 652 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 653 #ifdef MAC 654 mac_ip6q_destroy(q6); 655 #endif 656 free(q6, M_FTABLE); 657 atomic_subtract_int(&V_frag6_nfragpackets, 1); 658 659 goto dropfrag; 660 } 661 662 /* 663 * Store NXT to the original. 664 */ 665 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 666 (caddr_t)&nxt); 667 668 frag6_remque(q6, hash); 669 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 670 #ifdef MAC 671 mac_ip6q_reassemble(q6, m); 672 mac_ip6q_destroy(q6); 673 #endif 674 free(q6, M_FTABLE); 675 atomic_subtract_int(&V_frag6_nfragpackets, 1); 676 677 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 678 int plen = 0; 679 for (t = m; t; t = t->m_next) 680 plen += t->m_len; 681 m->m_pkthdr.len = plen; 682 } 683 684 #ifdef RSS 685 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 686 M_NOWAIT); 687 if (mtag == NULL) 688 goto dropfrag; 689 690 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 691 ip6dc->ip6dc_nxt = nxt; 692 ip6dc->ip6dc_off = offset; 693 694 m_tag_prepend(m, mtag); 695 #endif 696 697 IP6Q_UNLOCK(hash); 698 IP6STAT_INC(ip6s_reassembled); 699 in6_ifstat_inc(dstifp, ifs6_reass_ok); 700 701 #ifdef RSS 702 /* 703 * Queue/dispatch for reprocessing. 704 */ 705 netisr_dispatch(NETISR_IPV6_DIRECT, m); 706 return IPPROTO_DONE; 707 #endif 708 709 /* 710 * Tell launch routine the next header 711 */ 712 713 *mp = m; 714 *offp = offset; 715 716 return nxt; 717 718 dropfrag: 719 IP6Q_UNLOCK(hash); 720 in6_ifstat_inc(dstifp, ifs6_reass_fail); 721 IP6STAT_INC(ip6s_fragdropped); 722 m_freem(m); 723 return IPPROTO_DONE; 724 } 725 726 /* 727 * Free a fragment reassembly header and all 728 * associated datagrams. 729 */ 730 static void 731 frag6_freef(struct ip6q *q6, uint32_t bucket) 732 { 733 struct ip6asfrag *af6, *down6; 734 735 IP6Q_LOCK_ASSERT(bucket); 736 737 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 738 af6 = down6) { 739 struct mbuf *m = IP6_REASS_MBUF(af6); 740 741 down6 = af6->ip6af_down; 742 frag6_deq(af6, bucket); 743 744 /* 745 * Return ICMP time exceeded error for the 1st fragment. 746 * Just free other fragments. 747 */ 748 if (af6->ip6af_off == 0) { 749 struct ip6_hdr *ip6; 750 751 /* adjust pointer */ 752 ip6 = mtod(m, struct ip6_hdr *); 753 754 /* restore source and destination addresses */ 755 ip6->ip6_src = q6->ip6q_src; 756 ip6->ip6_dst = q6->ip6q_dst; 757 758 icmp6_error(m, ICMP6_TIME_EXCEEDED, 759 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 760 } else 761 m_freem(m); 762 free(af6, M_FTABLE); 763 } 764 frag6_remque(q6, bucket); 765 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 766 #ifdef MAC 767 mac_ip6q_destroy(q6); 768 #endif 769 free(q6, M_FTABLE); 770 atomic_subtract_int(&V_frag6_nfragpackets, 1); 771 } 772 773 /* 774 * Put an ip fragment on a reassembly chain. 775 * Like insque, but pointers in middle of structure. 776 */ 777 static void 778 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6, 779 uint32_t bucket __unused) 780 { 781 782 IP6Q_LOCK_ASSERT(bucket); 783 784 af6->ip6af_up = up6; 785 af6->ip6af_down = up6->ip6af_down; 786 up6->ip6af_down->ip6af_up = af6; 787 up6->ip6af_down = af6; 788 } 789 790 /* 791 * To frag6_enq as remque is to insque. 792 */ 793 static void 794 frag6_deq(struct ip6asfrag *af6, uint32_t bucket __unused) 795 { 796 797 IP6Q_LOCK_ASSERT(bucket); 798 799 af6->ip6af_up->ip6af_down = af6->ip6af_down; 800 af6->ip6af_down->ip6af_up = af6->ip6af_up; 801 } 802 803 static void 804 frag6_insque_head(struct ip6q *new, struct ip6q *old, uint32_t bucket) 805 { 806 807 IP6Q_LOCK_ASSERT(bucket); 808 KASSERT(IP6Q_HEAD(bucket) == old, 809 ("%s: attempt to insert at head of wrong bucket" 810 " (bucket=%u, old=%p)", __func__, bucket, old)); 811 812 new->ip6q_prev = old; 813 new->ip6q_next = old->ip6q_next; 814 old->ip6q_next->ip6q_prev= new; 815 old->ip6q_next = new; 816 V_ip6q[bucket].count++; 817 } 818 819 static void 820 frag6_remque(struct ip6q *p6, uint32_t bucket) 821 { 822 823 IP6Q_LOCK_ASSERT(bucket); 824 825 p6->ip6q_prev->ip6q_next = p6->ip6q_next; 826 p6->ip6q_next->ip6q_prev = p6->ip6q_prev; 827 V_ip6q[bucket].count--; 828 } 829 830 /* 831 * IPv6 reassembling timer processing; 832 * if a timer expires on a reassembly 833 * queue, discard it. 834 */ 835 void 836 frag6_slowtimo(void) 837 { 838 VNET_ITERATOR_DECL(vnet_iter); 839 struct ip6q *head, *q6; 840 int i; 841 842 VNET_LIST_RLOCK_NOSLEEP(); 843 VNET_FOREACH(vnet_iter) { 844 CURVNET_SET(vnet_iter); 845 for (i = 0; i < IP6REASS_NHASH; i++) { 846 IP6Q_LOCK(i); 847 head = IP6Q_HEAD(i); 848 q6 = head->ip6q_next; 849 if (q6 == NULL) { 850 /* 851 * XXXJTL: This should never happen. This 852 * should turn into an assertion. 853 */ 854 IP6Q_UNLOCK(i); 855 continue; 856 } 857 while (q6 != head) { 858 --q6->ip6q_ttl; 859 q6 = q6->ip6q_next; 860 if (q6->ip6q_prev->ip6q_ttl == 0) { 861 IP6STAT_INC(ip6s_fragtimeout); 862 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 863 frag6_freef(q6->ip6q_prev, i); 864 } 865 } 866 /* 867 * If we are over the maximum number of fragments 868 * (due to the limit being lowered), drain off 869 * enough to get down to the new limit. 870 * Note that we drain all reassembly queues if 871 * maxfragpackets is 0 (fragmentation is disabled), 872 * and don't enforce a limit when maxfragpackets 873 * is negative. 874 */ 875 while ((V_ip6_maxfragpackets == 0 || 876 (V_ip6_maxfragpackets > 0 && 877 V_ip6q[i].count > V_ip6_maxfragbucketsize)) && 878 head->ip6q_prev != head) { 879 IP6STAT_INC(ip6s_fragoverflow); 880 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 881 frag6_freef(head->ip6q_prev, i); 882 } 883 IP6Q_UNLOCK(i); 884 } 885 /* 886 * If we are still over the maximum number of fragmented 887 * packets, drain off enough to get down to the new limit. 888 */ 889 i = 0; 890 while (V_ip6_maxfragpackets >= 0 && 891 V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets) { 892 IP6Q_LOCK(i); 893 head = IP6Q_HEAD(i); 894 if (head->ip6q_prev != head) { 895 IP6STAT_INC(ip6s_fragoverflow); 896 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 897 frag6_freef(head->ip6q_prev, i); 898 } 899 IP6Q_UNLOCK(i); 900 i = (i + 1) % IP6REASS_NHASH; 901 } 902 CURVNET_RESTORE(); 903 } 904 VNET_LIST_RUNLOCK_NOSLEEP(); 905 } 906 907 /* 908 * Drain off all datagram fragments. 909 */ 910 void 911 frag6_drain(void) 912 { 913 VNET_ITERATOR_DECL(vnet_iter); 914 struct ip6q *head; 915 int i; 916 917 VNET_LIST_RLOCK_NOSLEEP(); 918 VNET_FOREACH(vnet_iter) { 919 CURVNET_SET(vnet_iter); 920 for (i = 0; i < IP6REASS_NHASH; i++) { 921 if (IP6Q_TRYLOCK(i) == 0) 922 continue; 923 head = IP6Q_HEAD(i); 924 while (head->ip6q_next != head) { 925 IP6STAT_INC(ip6s_fragdropped); 926 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 927 frag6_freef(head->ip6q_next, i); 928 } 929 IP6Q_UNLOCK(i); 930 } 931 CURVNET_RESTORE(); 932 } 933 VNET_LIST_RUNLOCK_NOSLEEP(); 934 } 935 936 int 937 ip6_deletefraghdr(struct mbuf *m, int offset, int wait) 938 { 939 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 940 struct mbuf *t; 941 942 /* Delete frag6 header. */ 943 if (m->m_len >= offset + sizeof(struct ip6_frag)) { 944 /* This is the only possible case with !PULLDOWN_TEST. */ 945 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), 946 offset); 947 m->m_data += sizeof(struct ip6_frag); 948 m->m_len -= sizeof(struct ip6_frag); 949 } else { 950 /* This comes with no copy if the boundary is on cluster. */ 951 if ((t = m_split(m, offset, wait)) == NULL) 952 return (ENOMEM); 953 m_adj(t, sizeof(struct ip6_frag)); 954 m_cat(m, t); 955 } 956 957 m->m_flags |= M_FRAGMENTED; 958 return (0); 959 }
Cache object: da01b1e05fac157f300b4c20d068ec33
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