1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * Copyright (c) 2019 Netflix, Inc. 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 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_rss.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/domain.h> 43 #include <sys/eventhandler.h> 44 #include <sys/hash.h> 45 #include <sys/kernel.h> 46 #include <sys/malloc.h> 47 #include <sys/mbuf.h> 48 #include <sys/protosw.h> 49 #include <sys/queue.h> 50 #include <sys/socket.h> 51 #include <sys/sysctl.h> 52 #include <sys/syslog.h> 53 54 #include <net/if.h> 55 #include <net/if_var.h> 56 #include <net/netisr.h> 57 #include <net/route.h> 58 #include <net/vnet.h> 59 60 #include <netinet/in.h> 61 #include <netinet/in_var.h> 62 #include <netinet/ip6.h> 63 #include <netinet6/ip6_var.h> 64 #include <netinet/icmp6.h> 65 #include <netinet/in_systm.h> /* For ECN definitions. */ 66 #include <netinet/ip.h> /* For ECN definitions. */ 67 68 #ifdef MAC 69 #include <security/mac/mac_framework.h> 70 #endif 71 72 /* 73 * A "big picture" of how IPv6 fragment queues are all linked together. 74 * 75 * struct ip6qbucket ip6qb[...]; hashed buckets 76 * |||||||| 77 * | 78 * +--- TAILQ(struct ip6q, packets) *q6; tailq entries holding 79 * |||||||| fragmented packets 80 * | (1 per original packet) 81 * | 82 * +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6; tailq entries of IPv6 83 * | *ip6af;fragment packets 84 * | for one original packet 85 * + *mbuf 86 */ 87 88 /* Reassembly headers are stored in hash buckets. */ 89 #define IP6REASS_NHASH_LOG2 10 90 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2) 91 #define IP6REASS_HMASK (IP6REASS_NHASH - 1) 92 93 TAILQ_HEAD(ip6qhead, ip6q); 94 struct ip6qbucket { 95 struct ip6qhead packets; 96 struct mtx lock; 97 int count; 98 }; 99 100 struct ip6asfrag { 101 TAILQ_ENTRY(ip6asfrag) ip6af_tq; 102 struct mbuf *ip6af_m; 103 int ip6af_offset; /* Offset in ip6af_m to next header. */ 104 int ip6af_frglen; /* Fragmentable part length. */ 105 int ip6af_off; /* Fragment offset. */ 106 bool ip6af_mff; /* More fragment bit in frag off. */ 107 }; 108 109 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header"); 110 111 #ifdef VIMAGE 112 /* A flag to indicate if IPv6 fragmentation is initialized. */ 113 VNET_DEFINE_STATIC(bool, frag6_on); 114 #define V_frag6_on VNET(frag6_on) 115 #endif 116 117 /* System wide (global) maximum and count of packets in reassembly queues. */ 118 static int ip6_maxfrags; 119 static volatile u_int frag6_nfrags = 0; 120 121 /* Maximum and current packets in per-VNET reassembly queue. */ 122 VNET_DEFINE_STATIC(int, ip6_maxfragpackets); 123 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets); 124 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) 125 #define V_frag6_nfragpackets VNET(frag6_nfragpackets) 126 127 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */ 128 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize); 129 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket); 130 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize) 131 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket) 132 133 /* Per-VNET reassembly queue buckets. */ 134 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]); 135 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed); 136 #define V_ip6qb VNET(ip6qb) 137 #define V_ip6qb_hashseed VNET(ip6qb_hashseed) 138 139 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock) 140 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock) 141 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED) 142 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock) 143 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].packets) 144 145 /* 146 * By default, limit the number of IP6 fragments across all reassembly 147 * queues to 1/32 of the total number of mbuf clusters. 148 * 149 * Limit the total number of reassembly queues per VNET to the 150 * IP6 fragment limit, but ensure the limit will not allow any bucket 151 * to grow above 100 items. (The bucket limit is 152 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct 153 * multiplier to reach a 100-item limit.) 154 * The 100-item limit was chosen as brief testing seems to show that 155 * this produces "reasonable" performance on some subset of systems 156 * under DoS attack. 157 */ 158 #define IP6_MAXFRAGS (nmbclusters / 32) 159 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) 160 161 162 /* 163 * Sysctls and helper function. 164 */ 165 SYSCTL_DECL(_net_inet6_ip6); 166 167 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags, 168 CTLFLAG_RD, __DEVOLATILE(u_int *, &frag6_nfrags), 0, 169 "Global number of IPv6 fragments across all reassembly queues."); 170 171 static void 172 frag6_set_bucketsize(void) 173 { 174 int i; 175 176 if ((i = V_ip6_maxfragpackets) > 0) 177 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); 178 } 179 180 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, 181 CTLFLAG_RW, &ip6_maxfrags, 0, 182 "Maximum allowed number of outstanding IPv6 packet fragments. " 183 "A value of 0 means no fragmented packets will be accepted, while a " 184 "a value of -1 means no limit"); 185 186 static int 187 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS) 188 { 189 int error, val; 190 191 val = V_ip6_maxfragpackets; 192 error = sysctl_handle_int(oidp, &val, 0, req); 193 if (error != 0 || !req->newptr) 194 return (error); 195 V_ip6_maxfragpackets = val; 196 frag6_set_bucketsize(); 197 return (0); 198 } 199 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, 200 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, NULL, 0, 201 sysctl_ip6_maxfragpackets, "I", 202 "Default maximum number of outstanding fragmented IPv6 packets. " 203 "A value of 0 means no fragmented packets will be accepted, while a " 204 "a value of -1 means no limit"); 205 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets, 206 CTLFLAG_VNET | CTLFLAG_RD, 207 __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0, 208 "Per-VNET number of IPv6 fragments across all reassembly queues."); 209 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket, 210 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0, 211 "Maximum allowed number of fragments per packet"); 212 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize, 213 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0, 214 "Maximum number of reassembly queues per hash bucket"); 215 216 217 /* 218 * Remove the IPv6 fragmentation header from the mbuf. 219 */ 220 int 221 ip6_deletefraghdr(struct mbuf *m, int offset, int wait) 222 { 223 struct ip6_hdr *ip6; 224 struct mbuf *t; 225 226 /* Delete frag6 header. */ 227 if (m->m_len >= offset + sizeof(struct ip6_frag)) { 228 229 /* This is the only possible case with !PULLDOWN_TEST. */ 230 ip6 = mtod(m, struct ip6_hdr *); 231 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), 232 offset); 233 m->m_data += sizeof(struct ip6_frag); 234 m->m_len -= sizeof(struct ip6_frag); 235 } else { 236 237 /* This comes with no copy if the boundary is on cluster. */ 238 if ((t = m_split(m, offset, wait)) == NULL) 239 return (ENOMEM); 240 m_adj(t, sizeof(struct ip6_frag)); 241 m_cat(m, t); 242 } 243 244 m->m_flags |= M_FRAGMENTED; 245 return (0); 246 } 247 248 /* 249 * Free a fragment reassembly header and all associated datagrams. 250 */ 251 static void 252 frag6_freef(struct ip6q *q6, uint32_t bucket) 253 { 254 struct ip6_hdr *ip6; 255 struct ip6asfrag *af6; 256 struct mbuf *m; 257 258 IP6QB_LOCK_ASSERT(bucket); 259 260 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 261 262 m = af6->ip6af_m; 263 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 264 265 /* 266 * Return ICMP time exceeded error for the 1st fragment. 267 * Just free other fragments. 268 */ 269 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { 270 271 /* Adjust pointer. */ 272 ip6 = mtod(m, struct ip6_hdr *); 273 274 /* Restore source and destination addresses. */ 275 ip6->ip6_src = q6->ip6q_src; 276 ip6->ip6_dst = q6->ip6q_dst; 277 278 icmp6_error(m, ICMP6_TIME_EXCEEDED, 279 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 280 } else 281 m_freem(m); 282 283 free(af6, M_FRAG6); 284 } 285 286 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq); 287 V_ip6qb[bucket].count--; 288 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 289 #ifdef MAC 290 mac_ip6q_destroy(q6); 291 #endif 292 free(q6, M_FRAG6); 293 atomic_subtract_int(&V_frag6_nfragpackets, 1); 294 } 295 296 /* 297 * Drain off all datagram fragments belonging to 298 * the given network interface. 299 */ 300 static void 301 frag6_cleanup(void *arg __unused, struct ifnet *ifp) 302 { 303 struct ip6qhead *head; 304 struct ip6q *q6; 305 struct ip6asfrag *af6; 306 uint32_t bucket; 307 308 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 309 310 CURVNET_SET_QUIET(ifp->if_vnet); 311 #ifdef VIMAGE 312 /* 313 * Skip processing if IPv6 reassembly is not initialised or 314 * torn down by frag6_destroy(). 315 */ 316 if (!V_frag6_on) { 317 CURVNET_RESTORE(); 318 return; 319 } 320 #endif 321 322 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 323 IP6QB_LOCK(bucket); 324 head = IP6QB_HEAD(bucket); 325 /* Scan fragment list. */ 326 TAILQ_FOREACH(q6, head, ip6q_tq) { 327 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 328 329 /* Clear no longer valid rcvif pointer. */ 330 if (af6->ip6af_m->m_pkthdr.rcvif == ifp) 331 af6->ip6af_m->m_pkthdr.rcvif = NULL; 332 } 333 } 334 IP6QB_UNLOCK(bucket); 335 } 336 CURVNET_RESTORE(); 337 } 338 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); 339 340 /* 341 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 342 * each other, in terms of next header field handling in fragment header. 343 * While the sender will use the same value for all of the fragmented packets, 344 * receiver is suggested not to check for consistency. 345 * 346 * Fragment rules (p18,p19): 347 * (2) A Fragment header containing: 348 * The Next Header value that identifies the first header 349 * after the Per-Fragment headers of the original packet. 350 * -> next header field is same for all fragments 351 * 352 * Reassembly rule (p20): 353 * The Next Header field of the last header of the Per-Fragment 354 * headers is obtained from the Next Header field of the first 355 * fragment's Fragment header. 356 * -> should grab it from the first fragment only 357 * 358 * The following note also contradicts with fragment rule - no one is going to 359 * send different fragment with different next header field. 360 * 361 * Additional note (p22) [not an error]: 362 * The Next Header values in the Fragment headers of different 363 * fragments of the same original packet may differ. Only the value 364 * from the Offset zero fragment packet is used for reassembly. 365 * -> should grab it from the first fragment only 366 * 367 * There is no explicit reason given in the RFC. Historical reason maybe? 368 */ 369 /* 370 * Fragment input. 371 */ 372 int 373 frag6_input(struct mbuf **mp, int *offp, int proto) 374 { 375 struct mbuf *m, *t; 376 struct ip6_hdr *ip6; 377 struct ip6_frag *ip6f; 378 struct ip6qhead *head; 379 struct ip6q *q6; 380 struct ip6asfrag *af6, *ip6af, *af6tmp; 381 struct in6_ifaddr *ia6; 382 struct ifnet *dstifp, *srcifp; 383 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 384 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 385 uint32_t bucket, *hashkeyp; 386 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 387 int nxt, offset, plen; 388 uint8_t ecn, ecn0; 389 bool only_frag; 390 #ifdef RSS 391 struct ip6_direct_ctx *ip6dc; 392 struct m_tag *mtag; 393 #endif 394 395 m = *mp; 396 offset = *offp; 397 398 ip6 = mtod(m, struct ip6_hdr *); 399 #ifndef PULLDOWN_TEST 400 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 401 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 402 #else 403 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 404 if (ip6f == NULL) 405 return (IPPROTO_DONE); 406 #endif 407 408 dstifp = NULL; 409 /* Find the destination interface of the packet. */ 410 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 411 if (ia6 != NULL) { 412 dstifp = ia6->ia_ifp; 413 ifa_free(&ia6->ia_ifa); 414 } 415 416 /* Jumbo payload cannot contain a fragment header. */ 417 if (ip6->ip6_plen == 0) { 418 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 419 in6_ifstat_inc(dstifp, ifs6_reass_fail); 420 return (IPPROTO_DONE); 421 } 422 423 /* 424 * Check whether fragment packet's fragment length is a 425 * multiple of 8 octets (unless it is the last one). 426 * sizeof(struct ip6_frag) == 8 427 * sizeof(struct ip6_hdr) = 40 428 */ 429 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 430 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 431 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 432 offsetof(struct ip6_hdr, ip6_plen)); 433 in6_ifstat_inc(dstifp, ifs6_reass_fail); 434 return (IPPROTO_DONE); 435 } 436 437 IP6STAT_INC(ip6s_fragments); 438 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 439 440 /* Offset now points to data portion. */ 441 offset += sizeof(struct ip6_frag); 442 443 /* 444 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 445 * unrelated to any reassembly. Still need to remove the frag hdr. 446 * See RFC 6946 and section 4.5 of RFC 8200. 447 */ 448 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 449 IP6STAT_INC(ip6s_atomicfrags); 450 /* XXX-BZ handle correctly. */ 451 in6_ifstat_inc(dstifp, ifs6_reass_ok); 452 *offp = offset; 453 m->m_flags |= M_FRAGMENTED; 454 return (ip6f->ip6f_nxt); 455 } 456 457 /* Get fragment length and discard 0-byte fragments. */ 458 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 459 if (frgpartlen == 0) { 460 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 461 offsetof(struct ip6_hdr, ip6_plen)); 462 in6_ifstat_inc(dstifp, ifs6_reass_fail); 463 IP6STAT_INC(ip6s_fragdropped); 464 return (IPPROTO_DONE); 465 } 466 467 /* 468 * Enforce upper bound on number of fragments for the entire system. 469 * If maxfrag is 0, never accept fragments. 470 * If maxfrag is -1, accept all fragments without limitation. 471 */ 472 if (ip6_maxfrags < 0) 473 ; 474 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 475 goto dropfrag2; 476 477 /* 478 * Validate that a full header chain to the ULP is present in the 479 * packet containing the first fragment as per RFC RFC7112 and 480 * RFC 8200 pages 18,19: 481 * The first fragment packet is composed of: 482 * (3) Extension headers, if any, and the Upper-Layer header. These 483 * headers must be in the first fragment. ... 484 */ 485 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 486 /* XXX TODO. thj has D16851 open for this. */ 487 /* Send ICMPv6 4,3 in case of violation. */ 488 489 /* Store receive network interface pointer for later. */ 490 srcifp = m->m_pkthdr.rcvif; 491 492 /* Generate a hash value for fragment bucket selection. */ 493 hashkeyp = hashkey; 494 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 495 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 496 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 497 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 498 *hashkeyp = ip6f->ip6f_ident; 499 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 500 bucket &= IP6REASS_HMASK; 501 IP6QB_LOCK(bucket); 502 head = IP6QB_HEAD(bucket); 503 504 TAILQ_FOREACH(q6, head, ip6q_tq) 505 if (ip6f->ip6f_ident == q6->ip6q_ident && 506 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 507 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 508 #ifdef MAC 509 && mac_ip6q_match(m, q6) 510 #endif 511 ) 512 break; 513 514 only_frag = false; 515 if (q6 == NULL) { 516 517 /* A first fragment to arrive creates a reassembly queue. */ 518 only_frag = true; 519 520 /* 521 * Enforce upper bound on number of fragmented packets 522 * for which we attempt reassembly; 523 * If maxfragpackets is 0, never accept fragments. 524 * If maxfragpackets is -1, accept all fragments without 525 * limitation. 526 */ 527 if (V_ip6_maxfragpackets < 0) 528 ; 529 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 530 atomic_load_int(&V_frag6_nfragpackets) >= 531 (u_int)V_ip6_maxfragpackets) 532 goto dropfrag; 533 534 /* Allocate IPv6 fragement packet queue entry. */ 535 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 536 M_NOWAIT | M_ZERO); 537 if (q6 == NULL) 538 goto dropfrag; 539 #ifdef MAC 540 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 541 free(q6, M_FRAG6); 542 goto dropfrag; 543 } 544 mac_ip6q_create(m, q6); 545 #endif 546 atomic_add_int(&V_frag6_nfragpackets, 1); 547 548 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 549 TAILQ_INIT(&q6->ip6q_frags); 550 q6->ip6q_ident = ip6f->ip6f_ident; 551 q6->ip6q_ttl = IPV6_FRAGTTL; 552 q6->ip6q_src = ip6->ip6_src; 553 q6->ip6q_dst = ip6->ip6_dst; 554 q6->ip6q_ecn = 555 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 556 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 557 558 /* Add the fragemented packet to the bucket. */ 559 TAILQ_INSERT_HEAD(head, q6, ip6q_tq); 560 V_ip6qb[bucket].count++; 561 } 562 563 /* 564 * If it is the 1st fragment, record the length of the 565 * unfragmentable part and the next header of the fragment header. 566 * Assume the first 1st fragement to arrive will be correct. 567 * We do not have any duplicate checks here yet so another packet 568 * with fragoff == 0 could come and overwrite the ip6q_unfrglen 569 * and worse, the next header, at any time. 570 */ 571 if (fragoff == 0 && q6->ip6q_unfrglen == -1) { 572 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 573 sizeof(struct ip6_frag); 574 q6->ip6q_nxt = ip6f->ip6f_nxt; 575 /* XXX ECN? */ 576 } 577 578 /* 579 * Check that the reassembled packet would not exceed 65535 bytes 580 * in size. 581 * If it would exceed, discard the fragment and return an ICMP error. 582 */ 583 if (q6->ip6q_unfrglen >= 0) { 584 /* The 1st fragment has already arrived. */ 585 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 586 if (only_frag) { 587 TAILQ_REMOVE(head, q6, ip6q_tq); 588 V_ip6qb[bucket].count--; 589 atomic_subtract_int(&V_frag6_nfragpackets, 1); 590 #ifdef MAC 591 mac_ip6q_destroy(q6); 592 #endif 593 free(q6, M_FRAG6); 594 } 595 IP6QB_UNLOCK(bucket); 596 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 597 offset - sizeof(struct ip6_frag) + 598 offsetof(struct ip6_frag, ip6f_offlg)); 599 return (IPPROTO_DONE); 600 } 601 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 602 if (only_frag) { 603 TAILQ_REMOVE(head, q6, ip6q_tq); 604 V_ip6qb[bucket].count--; 605 atomic_subtract_int(&V_frag6_nfragpackets, 1); 606 #ifdef MAC 607 mac_ip6q_destroy(q6); 608 #endif 609 free(q6, M_FRAG6); 610 } 611 IP6QB_UNLOCK(bucket); 612 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 613 offset - sizeof(struct ip6_frag) + 614 offsetof(struct ip6_frag, ip6f_offlg)); 615 return (IPPROTO_DONE); 616 } 617 618 /* 619 * If it is the first fragment, do the above check for each 620 * fragment already stored in the reassembly queue. 621 */ 622 if (fragoff == 0 && !only_frag) { 623 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { 624 625 if (q6->ip6q_unfrglen + af6->ip6af_off + 626 af6->ip6af_frglen > IPV6_MAXPACKET) { 627 struct ip6_hdr *ip6err; 628 struct mbuf *merr; 629 int erroff; 630 631 merr = af6->ip6af_m; 632 erroff = af6->ip6af_offset; 633 634 /* Dequeue the fragment. */ 635 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 636 q6->ip6q_nfrag--; 637 atomic_subtract_int(&frag6_nfrags, 1); 638 free(af6, M_FRAG6); 639 640 /* Set a valid receive interface pointer. */ 641 merr->m_pkthdr.rcvif = srcifp; 642 643 /* Adjust pointer. */ 644 ip6err = mtod(merr, struct ip6_hdr *); 645 646 /* 647 * Restore source and destination addresses 648 * in the erroneous IPv6 header. 649 */ 650 ip6err->ip6_src = q6->ip6q_src; 651 ip6err->ip6_dst = q6->ip6q_dst; 652 653 icmp6_error(merr, ICMP6_PARAM_PROB, 654 ICMP6_PARAMPROB_HEADER, 655 erroff - sizeof(struct ip6_frag) + 656 offsetof(struct ip6_frag, ip6f_offlg)); 657 } 658 } 659 } 660 661 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 662 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 663 M_NOWAIT | M_ZERO); 664 if (ip6af == NULL) 665 goto dropfrag; 666 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; 667 ip6af->ip6af_off = fragoff; 668 ip6af->ip6af_frglen = frgpartlen; 669 ip6af->ip6af_offset = offset; 670 ip6af->ip6af_m = m; 671 672 if (only_frag) { 673 /* 674 * Do a manual insert rather than a hard-to-understand cast 675 * to a different type relying on data structure order to work. 676 */ 677 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); 678 goto postinsert; 679 } 680 681 /* Do duplicate, condition, and boundry checks. */ 682 /* 683 * Handle ECN by comparing this segment with the first one; 684 * if CE is set, do not lose CE. 685 * Drop if CE and not-ECT are mixed for the same packet. 686 */ 687 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 688 ecn0 = q6->ip6q_ecn; 689 if (ecn == IPTOS_ECN_CE) { 690 if (ecn0 == IPTOS_ECN_NOTECT) { 691 free(ip6af, M_FRAG6); 692 goto dropfrag; 693 } 694 if (ecn0 != IPTOS_ECN_CE) 695 q6->ip6q_ecn = IPTOS_ECN_CE; 696 } 697 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 698 free(ip6af, M_FRAG6); 699 goto dropfrag; 700 } 701 702 /* Find a fragmented part which begins after this one does. */ 703 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) 704 if (af6->ip6af_off > ip6af->ip6af_off) 705 break; 706 707 /* 708 * If the incoming framgent overlaps some existing fragments in 709 * the reassembly queue, drop both the new fragment and the 710 * entire reassembly queue. However, if the new fragment 711 * is an exact duplicate of an existing fragment, only silently 712 * drop the existing fragment and leave the fragmentation queue 713 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 714 */ 715 if (af6 != NULL) 716 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); 717 else 718 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 719 if (af6tmp != NULL) { 720 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - 721 ip6af->ip6af_off > 0) { 722 if (af6tmp->ip6af_off != ip6af->ip6af_off || 723 af6tmp->ip6af_frglen != ip6af->ip6af_frglen) 724 frag6_freef(q6, bucket); 725 free(ip6af, M_FRAG6); 726 goto dropfrag; 727 } 728 } 729 if (af6 != NULL) { 730 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 731 af6->ip6af_off > 0) { 732 if (af6->ip6af_off != ip6af->ip6af_off || 733 af6->ip6af_frglen != ip6af->ip6af_frglen) 734 frag6_freef(q6, bucket); 735 free(ip6af, M_FRAG6); 736 goto dropfrag; 737 } 738 } 739 740 #ifdef MAC 741 mac_ip6q_update(m, q6); 742 #endif 743 744 /* 745 * Stick new segment in its place; check for complete reassembly. 746 * If not complete, check fragment limit. Move to front of packet 747 * queue, as we are the most recently active fragmented packet. 748 */ 749 if (af6 != NULL) 750 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); 751 else 752 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); 753 postinsert: 754 atomic_add_int(&frag6_nfrags, 1); 755 q6->ip6q_nfrag++; 756 757 plen = 0; 758 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 759 if (af6->ip6af_off != plen) { 760 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 761 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 762 frag6_freef(q6, bucket); 763 } 764 IP6QB_UNLOCK(bucket); 765 return (IPPROTO_DONE); 766 } 767 plen += af6->ip6af_frglen; 768 } 769 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 770 if (af6->ip6af_mff) { 771 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 772 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 773 frag6_freef(q6, bucket); 774 } 775 IP6QB_UNLOCK(bucket); 776 return (IPPROTO_DONE); 777 } 778 779 /* Reassembly is complete; concatenate fragments. */ 780 ip6af = TAILQ_FIRST(&q6->ip6q_frags); 781 t = m = ip6af->ip6af_m; 782 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); 783 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 784 m->m_pkthdr.csum_flags &= 785 af6->ip6af_m->m_pkthdr.csum_flags; 786 m->m_pkthdr.csum_data += 787 af6->ip6af_m->m_pkthdr.csum_data; 788 789 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 790 t = m_last(t); 791 m_adj(af6->ip6af_m, af6->ip6af_offset); 792 m_demote_pkthdr(af6->ip6af_m); 793 m_cat(t, af6->ip6af_m); 794 free(af6, M_FRAG6); 795 } 796 797 while (m->m_pkthdr.csum_data & 0xffff0000) 798 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 799 (m->m_pkthdr.csum_data >> 16); 800 801 /* Adjust offset to point where the original next header starts. */ 802 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 803 free(ip6af, M_FRAG6); 804 ip6 = mtod(m, struct ip6_hdr *); 805 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 806 if (q6->ip6q_ecn == IPTOS_ECN_CE) 807 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 808 nxt = q6->ip6q_nxt; 809 810 TAILQ_REMOVE(head, q6, ip6q_tq); 811 V_ip6qb[bucket].count--; 812 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 813 814 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { 815 #ifdef MAC 816 mac_ip6q_destroy(q6); 817 #endif 818 free(q6, M_FRAG6); 819 atomic_subtract_int(&V_frag6_nfragpackets, 1); 820 821 goto dropfrag; 822 } 823 824 /* Set nxt(-hdr field value) to the original value. */ 825 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 826 (caddr_t)&nxt); 827 828 #ifdef MAC 829 mac_ip6q_reassemble(q6, m); 830 mac_ip6q_destroy(q6); 831 #endif 832 free(q6, M_FRAG6); 833 atomic_subtract_int(&V_frag6_nfragpackets, 1); 834 835 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 836 837 plen = 0; 838 for (t = m; t; t = t->m_next) 839 plen += t->m_len; 840 m->m_pkthdr.len = plen; 841 /* Set a valid receive interface pointer. */ 842 m->m_pkthdr.rcvif = srcifp; 843 } 844 845 #ifdef RSS 846 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 847 M_NOWAIT); 848 if (mtag == NULL) 849 goto dropfrag; 850 851 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 852 ip6dc->ip6dc_nxt = nxt; 853 ip6dc->ip6dc_off = offset; 854 855 m_tag_prepend(m, mtag); 856 #endif 857 858 IP6QB_UNLOCK(bucket); 859 IP6STAT_INC(ip6s_reassembled); 860 in6_ifstat_inc(dstifp, ifs6_reass_ok); 861 862 #ifdef RSS 863 /* Queue/dispatch for reprocessing. */ 864 netisr_dispatch(NETISR_IPV6_DIRECT, m); 865 return (IPPROTO_DONE); 866 #endif 867 868 /* Tell launch routine the next header. */ 869 *mp = m; 870 *offp = offset; 871 872 return (nxt); 873 874 dropfrag: 875 IP6QB_UNLOCK(bucket); 876 dropfrag2: 877 in6_ifstat_inc(dstifp, ifs6_reass_fail); 878 IP6STAT_INC(ip6s_fragdropped); 879 m_freem(m); 880 return (IPPROTO_DONE); 881 } 882 883 /* 884 * IPv6 reassembling timer processing; 885 * if a timer expires on a reassembly queue, discard it. 886 */ 887 void 888 frag6_slowtimo(void) 889 { 890 VNET_ITERATOR_DECL(vnet_iter); 891 struct ip6qhead *head; 892 struct ip6q *q6, *q6tmp; 893 uint32_t bucket; 894 895 VNET_LIST_RLOCK_NOSLEEP(); 896 VNET_FOREACH(vnet_iter) { 897 CURVNET_SET(vnet_iter); 898 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 899 IP6QB_LOCK(bucket); 900 head = IP6QB_HEAD(bucket); 901 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) 902 if (--q6->ip6q_ttl == 0) { 903 IP6STAT_ADD(ip6s_fragtimeout, 904 q6->ip6q_nfrag); 905 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 906 frag6_freef(q6, bucket); 907 } 908 /* 909 * If we are over the maximum number of fragments 910 * (due to the limit being lowered), drain off 911 * enough to get down to the new limit. 912 * Note that we drain all reassembly queues if 913 * maxfragpackets is 0 (fragmentation is disabled), 914 * and do not enforce a limit when maxfragpackets 915 * is negative. 916 */ 917 while ((V_ip6_maxfragpackets == 0 || 918 (V_ip6_maxfragpackets > 0 && 919 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 920 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { 921 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 922 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 923 frag6_freef(q6, bucket); 924 } 925 IP6QB_UNLOCK(bucket); 926 } 927 /* 928 * If we are still over the maximum number of fragmented 929 * packets, drain off enough to get down to the new limit. 930 */ 931 bucket = 0; 932 while (V_ip6_maxfragpackets >= 0 && 933 atomic_load_int(&V_frag6_nfragpackets) > 934 (u_int)V_ip6_maxfragpackets) { 935 IP6QB_LOCK(bucket); 936 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); 937 if (q6 != NULL) { 938 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 939 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 940 frag6_freef(q6, bucket); 941 } 942 IP6QB_UNLOCK(bucket); 943 bucket = (bucket + 1) % IP6REASS_NHASH; 944 } 945 CURVNET_RESTORE(); 946 } 947 VNET_LIST_RUNLOCK_NOSLEEP(); 948 } 949 950 /* 951 * Eventhandler to adjust limits in case nmbclusters change. 952 */ 953 static void 954 frag6_change(void *tag) 955 { 956 VNET_ITERATOR_DECL(vnet_iter); 957 958 ip6_maxfrags = IP6_MAXFRAGS; 959 VNET_LIST_RLOCK_NOSLEEP(); 960 VNET_FOREACH(vnet_iter) { 961 CURVNET_SET(vnet_iter); 962 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 963 frag6_set_bucketsize(); 964 CURVNET_RESTORE(); 965 } 966 VNET_LIST_RUNLOCK_NOSLEEP(); 967 } 968 969 /* 970 * Initialise reassembly queue and fragment identifier. 971 */ 972 void 973 frag6_init(void) 974 { 975 uint32_t bucket; 976 977 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 978 frag6_set_bucketsize(); 979 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 980 TAILQ_INIT(IP6QB_HEAD(bucket)); 981 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); 982 V_ip6qb[bucket].count = 0; 983 } 984 V_ip6qb_hashseed = arc4random(); 985 V_ip6_maxfragsperpacket = 64; 986 #ifdef VIMAGE 987 V_frag6_on = true; 988 #endif 989 if (!IS_DEFAULT_VNET(curvnet)) 990 return; 991 992 ip6_maxfrags = IP6_MAXFRAGS; 993 EVENTHANDLER_REGISTER(nmbclusters_change, 994 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 995 } 996 997 /* 998 * Drain off all datagram fragments. 999 */ 1000 static void 1001 frag6_drain_one(void) 1002 { 1003 struct ip6q *q6; 1004 uint32_t bucket; 1005 1006 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1007 IP6QB_LOCK(bucket); 1008 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { 1009 IP6STAT_INC(ip6s_fragdropped); 1010 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 1011 frag6_freef(q6, bucket); 1012 } 1013 IP6QB_UNLOCK(bucket); 1014 } 1015 } 1016 1017 void 1018 frag6_drain(void) 1019 { 1020 VNET_ITERATOR_DECL(vnet_iter); 1021 1022 VNET_LIST_RLOCK_NOSLEEP(); 1023 VNET_FOREACH(vnet_iter) { 1024 CURVNET_SET(vnet_iter); 1025 frag6_drain_one(); 1026 CURVNET_RESTORE(); 1027 } 1028 VNET_LIST_RUNLOCK_NOSLEEP(); 1029 } 1030 1031 #ifdef VIMAGE 1032 /* 1033 * Clear up IPv6 reassembly structures. 1034 */ 1035 void 1036 frag6_destroy(void) 1037 { 1038 uint32_t bucket; 1039 1040 frag6_drain_one(); 1041 V_frag6_on = false; 1042 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1043 KASSERT(V_ip6qb[bucket].count == 0, 1044 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1045 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1046 mtx_destroy(&V_ip6qb[bucket].lock); 1047 } 1048 } 1049 #endif 1050