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 __unused) 222 { 223 struct ip6_hdr *ip6; 224 225 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag), 226 ("%s: ext headers not contigous in mbuf %p m_len %d >= " 227 "offset %d + %zu\n", __func__, m, m->m_len, offset, 228 sizeof(struct ip6_frag))); 229 230 /* Delete frag6 header. */ 231 ip6 = mtod(m, struct ip6_hdr *); 232 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset); 233 m->m_data += sizeof(struct ip6_frag); 234 m->m_len -= sizeof(struct ip6_frag); 235 m->m_flags |= M_FRAGMENTED; 236 237 return (0); 238 } 239 240 /* 241 * Free a fragment reassembly header and all associated datagrams. 242 */ 243 static void 244 frag6_freef(struct ip6q *q6, uint32_t bucket) 245 { 246 struct ip6_hdr *ip6; 247 struct ip6asfrag *af6; 248 struct mbuf *m; 249 250 IP6QB_LOCK_ASSERT(bucket); 251 252 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 253 254 m = af6->ip6af_m; 255 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 256 257 /* 258 * Return ICMP time exceeded error for the 1st fragment. 259 * Just free other fragments. 260 */ 261 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { 262 263 /* Adjust pointer. */ 264 ip6 = mtod(m, struct ip6_hdr *); 265 266 /* Restore source and destination addresses. */ 267 ip6->ip6_src = q6->ip6q_src; 268 ip6->ip6_dst = q6->ip6q_dst; 269 270 icmp6_error(m, ICMP6_TIME_EXCEEDED, 271 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 272 } else 273 m_freem(m); 274 275 free(af6, M_FRAG6); 276 } 277 278 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq); 279 V_ip6qb[bucket].count--; 280 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 281 #ifdef MAC 282 mac_ip6q_destroy(q6); 283 #endif 284 free(q6, M_FRAG6); 285 atomic_subtract_int(&V_frag6_nfragpackets, 1); 286 } 287 288 /* 289 * Drain off all datagram fragments belonging to 290 * the given network interface. 291 */ 292 static void 293 frag6_cleanup(void *arg __unused, struct ifnet *ifp) 294 { 295 struct ip6qhead *head; 296 struct ip6q *q6; 297 struct ip6asfrag *af6; 298 uint32_t bucket; 299 300 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 301 302 CURVNET_SET_QUIET(ifp->if_vnet); 303 #ifdef VIMAGE 304 /* 305 * Skip processing if IPv6 reassembly is not initialised or 306 * torn down by frag6_destroy(). 307 */ 308 if (!V_frag6_on) { 309 CURVNET_RESTORE(); 310 return; 311 } 312 #endif 313 314 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 315 IP6QB_LOCK(bucket); 316 head = IP6QB_HEAD(bucket); 317 /* Scan fragment list. */ 318 TAILQ_FOREACH(q6, head, ip6q_tq) { 319 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 320 321 /* Clear no longer valid rcvif pointer. */ 322 if (af6->ip6af_m->m_pkthdr.rcvif == ifp) 323 af6->ip6af_m->m_pkthdr.rcvif = NULL; 324 } 325 } 326 IP6QB_UNLOCK(bucket); 327 } 328 CURVNET_RESTORE(); 329 } 330 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); 331 332 /* 333 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 334 * each other, in terms of next header field handling in fragment header. 335 * While the sender will use the same value for all of the fragmented packets, 336 * receiver is suggested not to check for consistency. 337 * 338 * Fragment rules (p18,p19): 339 * (2) A Fragment header containing: 340 * The Next Header value that identifies the first header 341 * after the Per-Fragment headers of the original packet. 342 * -> next header field is same for all fragments 343 * 344 * Reassembly rule (p20): 345 * The Next Header field of the last header of the Per-Fragment 346 * headers is obtained from the Next Header field of the first 347 * fragment's Fragment header. 348 * -> should grab it from the first fragment only 349 * 350 * The following note also contradicts with fragment rule - no one is going to 351 * send different fragment with different next header field. 352 * 353 * Additional note (p22) [not an error]: 354 * The Next Header values in the Fragment headers of different 355 * fragments of the same original packet may differ. Only the value 356 * from the Offset zero fragment packet is used for reassembly. 357 * -> should grab it from the first fragment only 358 * 359 * There is no explicit reason given in the RFC. Historical reason maybe? 360 */ 361 /* 362 * Fragment input. 363 */ 364 int 365 frag6_input(struct mbuf **mp, int *offp, int proto) 366 { 367 struct mbuf *m, *t; 368 struct ip6_hdr *ip6; 369 struct ip6_frag *ip6f; 370 struct ip6qhead *head; 371 struct ip6q *q6; 372 struct ip6asfrag *af6, *ip6af, *af6tmp; 373 struct in6_ifaddr *ia6; 374 struct ifnet *dstifp, *srcifp; 375 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 376 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 377 uint32_t bucket, *hashkeyp; 378 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 379 int nxt, offset, plen; 380 uint8_t ecn, ecn0; 381 bool only_frag; 382 #ifdef RSS 383 struct ip6_direct_ctx *ip6dc; 384 struct m_tag *mtag; 385 #endif 386 387 m = *mp; 388 offset = *offp; 389 390 M_ASSERTPKTHDR(m); 391 392 m = m_pullup(m, offset + sizeof(struct ip6_frag)); 393 if (m == NULL) { 394 IP6STAT_INC(ip6s_exthdrtoolong); 395 *mp = NULL; 396 return (IPPROTO_DONE); 397 } 398 ip6 = mtod(m, struct ip6_hdr *); 399 400 dstifp = NULL; 401 /* Find the destination interface of the packet. */ 402 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 403 if (ia6 != NULL) { 404 dstifp = ia6->ia_ifp; 405 ifa_free(&ia6->ia_ifa); 406 } 407 408 /* Jumbo payload cannot contain a fragment header. */ 409 if (ip6->ip6_plen == 0) { 410 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 411 in6_ifstat_inc(dstifp, ifs6_reass_fail); 412 *mp = NULL; 413 return (IPPROTO_DONE); 414 } 415 416 /* 417 * Check whether fragment packet's fragment length is a 418 * multiple of 8 octets (unless it is the last one). 419 * sizeof(struct ip6_frag) == 8 420 * sizeof(struct ip6_hdr) = 40 421 */ 422 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 423 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 424 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 425 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 426 offsetof(struct ip6_hdr, ip6_plen)); 427 in6_ifstat_inc(dstifp, ifs6_reass_fail); 428 *mp = NULL; 429 return (IPPROTO_DONE); 430 } 431 432 IP6STAT_INC(ip6s_fragments); 433 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 434 435 /* 436 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 437 * unrelated to any reassembly. We need to remove the frag hdr 438 * which is ugly. 439 * See RFC 6946 and section 4.5 of RFC 8200. 440 */ 441 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 442 IP6STAT_INC(ip6s_atomicfrags); 443 nxt = ip6f->ip6f_nxt; 444 /* 445 * Set nxt(-hdr field value) to the original value. 446 * We cannot just set ip6->ip6_nxt as there might be 447 * an unfragmentable part with extension headers and 448 * we must update the last one. 449 */ 450 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 451 (caddr_t)&nxt); 452 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - 453 sizeof(struct ip6_frag)); 454 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) 455 goto dropfrag2; 456 m->m_pkthdr.len -= sizeof(struct ip6_frag); 457 in6_ifstat_inc(dstifp, ifs6_reass_ok); 458 *mp = m; 459 return (nxt); 460 } 461 462 /* Offset now points to data portion. */ 463 offset += sizeof(struct ip6_frag); 464 465 /* Get fragment length and discard 0-byte fragments. */ 466 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 467 if (frgpartlen == 0) { 468 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 469 offsetof(struct ip6_hdr, ip6_plen)); 470 in6_ifstat_inc(dstifp, ifs6_reass_fail); 471 IP6STAT_INC(ip6s_fragdropped); 472 *mp = NULL; 473 return (IPPROTO_DONE); 474 } 475 476 /* 477 * Enforce upper bound on number of fragments for the entire system. 478 * If maxfrag is 0, never accept fragments. 479 * If maxfrag is -1, accept all fragments without limitation. 480 */ 481 if (ip6_maxfrags < 0) 482 ; 483 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 484 goto dropfrag2; 485 486 /* 487 * Validate that a full header chain to the ULP is present in the 488 * packet containing the first fragment as per RFC RFC7112 and 489 * RFC 8200 pages 18,19: 490 * The first fragment packet is composed of: 491 * (3) Extension headers, if any, and the Upper-Layer header. These 492 * headers must be in the first fragment. ... 493 */ 494 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 495 /* XXX TODO. thj has D16851 open for this. */ 496 /* Send ICMPv6 4,3 in case of violation. */ 497 498 /* Store receive network interface pointer for later. */ 499 srcifp = m->m_pkthdr.rcvif; 500 501 /* Generate a hash value for fragment bucket selection. */ 502 hashkeyp = hashkey; 503 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 504 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 505 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 506 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 507 *hashkeyp = ip6f->ip6f_ident; 508 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 509 bucket &= IP6REASS_HMASK; 510 IP6QB_LOCK(bucket); 511 head = IP6QB_HEAD(bucket); 512 513 TAILQ_FOREACH(q6, head, ip6q_tq) 514 if (ip6f->ip6f_ident == q6->ip6q_ident && 515 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 516 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 517 #ifdef MAC 518 && mac_ip6q_match(m, q6) 519 #endif 520 ) 521 break; 522 523 only_frag = false; 524 if (q6 == NULL) { 525 526 /* A first fragment to arrive creates a reassembly queue. */ 527 only_frag = true; 528 529 /* 530 * Enforce upper bound on number of fragmented packets 531 * for which we attempt reassembly; 532 * If maxfragpackets is 0, never accept fragments. 533 * If maxfragpackets is -1, accept all fragments without 534 * limitation. 535 */ 536 if (V_ip6_maxfragpackets < 0) 537 ; 538 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 539 atomic_load_int(&V_frag6_nfragpackets) >= 540 (u_int)V_ip6_maxfragpackets) 541 goto dropfrag; 542 543 /* Allocate IPv6 fragement packet queue entry. */ 544 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 545 M_NOWAIT | M_ZERO); 546 if (q6 == NULL) 547 goto dropfrag; 548 #ifdef MAC 549 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 550 free(q6, M_FRAG6); 551 goto dropfrag; 552 } 553 mac_ip6q_create(m, q6); 554 #endif 555 atomic_add_int(&V_frag6_nfragpackets, 1); 556 557 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 558 TAILQ_INIT(&q6->ip6q_frags); 559 q6->ip6q_ident = ip6f->ip6f_ident; 560 q6->ip6q_ttl = IPV6_FRAGTTL; 561 q6->ip6q_src = ip6->ip6_src; 562 q6->ip6q_dst = ip6->ip6_dst; 563 q6->ip6q_ecn = 564 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 565 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 566 567 /* Add the fragemented packet to the bucket. */ 568 TAILQ_INSERT_HEAD(head, q6, ip6q_tq); 569 V_ip6qb[bucket].count++; 570 } 571 572 /* 573 * If it is the 1st fragment, record the length of the 574 * unfragmentable part and the next header of the fragment header. 575 * Assume the first 1st fragement to arrive will be correct. 576 * We do not have any duplicate checks here yet so another packet 577 * with fragoff == 0 could come and overwrite the ip6q_unfrglen 578 * and worse, the next header, at any time. 579 */ 580 if (fragoff == 0 && q6->ip6q_unfrglen == -1) { 581 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 582 sizeof(struct ip6_frag); 583 q6->ip6q_nxt = ip6f->ip6f_nxt; 584 /* XXX ECN? */ 585 } 586 587 /* 588 * Check that the reassembled packet would not exceed 65535 bytes 589 * in size. 590 * If it would exceed, discard the fragment and return an ICMP error. 591 */ 592 if (q6->ip6q_unfrglen >= 0) { 593 /* The 1st fragment has already arrived. */ 594 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 595 if (only_frag) { 596 TAILQ_REMOVE(head, q6, ip6q_tq); 597 V_ip6qb[bucket].count--; 598 atomic_subtract_int(&V_frag6_nfragpackets, 1); 599 #ifdef MAC 600 mac_ip6q_destroy(q6); 601 #endif 602 free(q6, M_FRAG6); 603 } 604 IP6QB_UNLOCK(bucket); 605 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 606 offset - sizeof(struct ip6_frag) + 607 offsetof(struct ip6_frag, ip6f_offlg)); 608 *mp = NULL; 609 return (IPPROTO_DONE); 610 } 611 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 612 if (only_frag) { 613 TAILQ_REMOVE(head, q6, ip6q_tq); 614 V_ip6qb[bucket].count--; 615 atomic_subtract_int(&V_frag6_nfragpackets, 1); 616 #ifdef MAC 617 mac_ip6q_destroy(q6); 618 #endif 619 free(q6, M_FRAG6); 620 } 621 IP6QB_UNLOCK(bucket); 622 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 623 offset - sizeof(struct ip6_frag) + 624 offsetof(struct ip6_frag, ip6f_offlg)); 625 *mp = NULL; 626 return (IPPROTO_DONE); 627 } 628 629 /* 630 * If it is the first fragment, do the above check for each 631 * fragment already stored in the reassembly queue. 632 */ 633 if (fragoff == 0 && !only_frag) { 634 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { 635 636 if (q6->ip6q_unfrglen + af6->ip6af_off + 637 af6->ip6af_frglen > IPV6_MAXPACKET) { 638 struct ip6_hdr *ip6err; 639 struct mbuf *merr; 640 int erroff; 641 642 merr = af6->ip6af_m; 643 erroff = af6->ip6af_offset; 644 645 /* Dequeue the fragment. */ 646 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 647 q6->ip6q_nfrag--; 648 atomic_subtract_int(&frag6_nfrags, 1); 649 free(af6, M_FRAG6); 650 651 /* Set a valid receive interface pointer. */ 652 merr->m_pkthdr.rcvif = srcifp; 653 654 /* Adjust pointer. */ 655 ip6err = mtod(merr, struct ip6_hdr *); 656 657 /* 658 * Restore source and destination addresses 659 * in the erroneous IPv6 header. 660 */ 661 ip6err->ip6_src = q6->ip6q_src; 662 ip6err->ip6_dst = q6->ip6q_dst; 663 664 icmp6_error(merr, ICMP6_PARAM_PROB, 665 ICMP6_PARAMPROB_HEADER, 666 erroff - sizeof(struct ip6_frag) + 667 offsetof(struct ip6_frag, ip6f_offlg)); 668 } 669 } 670 } 671 672 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 673 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 674 M_NOWAIT | M_ZERO); 675 if (ip6af == NULL) 676 goto dropfrag; 677 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; 678 ip6af->ip6af_off = fragoff; 679 ip6af->ip6af_frglen = frgpartlen; 680 ip6af->ip6af_offset = offset; 681 ip6af->ip6af_m = m; 682 683 if (only_frag) { 684 /* 685 * Do a manual insert rather than a hard-to-understand cast 686 * to a different type relying on data structure order to work. 687 */ 688 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); 689 goto postinsert; 690 } 691 692 /* Do duplicate, condition, and boundry checks. */ 693 /* 694 * Handle ECN by comparing this segment with the first one; 695 * if CE is set, do not lose CE. 696 * Drop if CE and not-ECT are mixed for the same packet. 697 */ 698 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 699 ecn0 = q6->ip6q_ecn; 700 if (ecn == IPTOS_ECN_CE) { 701 if (ecn0 == IPTOS_ECN_NOTECT) { 702 free(ip6af, M_FRAG6); 703 goto dropfrag; 704 } 705 if (ecn0 != IPTOS_ECN_CE) 706 q6->ip6q_ecn = IPTOS_ECN_CE; 707 } 708 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 709 free(ip6af, M_FRAG6); 710 goto dropfrag; 711 } 712 713 /* Find a fragmented part which begins after this one does. */ 714 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) 715 if (af6->ip6af_off > ip6af->ip6af_off) 716 break; 717 718 /* 719 * If the incoming framgent overlaps some existing fragments in 720 * the reassembly queue, drop both the new fragment and the 721 * entire reassembly queue. However, if the new fragment 722 * is an exact duplicate of an existing fragment, only silently 723 * drop the existing fragment and leave the fragmentation queue 724 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 725 */ 726 if (af6 != NULL) 727 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); 728 else 729 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 730 if (af6tmp != NULL) { 731 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - 732 ip6af->ip6af_off > 0) { 733 if (af6tmp->ip6af_off != ip6af->ip6af_off || 734 af6tmp->ip6af_frglen != ip6af->ip6af_frglen) 735 frag6_freef(q6, bucket); 736 free(ip6af, M_FRAG6); 737 goto dropfrag; 738 } 739 } 740 if (af6 != NULL) { 741 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 742 af6->ip6af_off > 0) { 743 if (af6->ip6af_off != ip6af->ip6af_off || 744 af6->ip6af_frglen != ip6af->ip6af_frglen) 745 frag6_freef(q6, bucket); 746 free(ip6af, M_FRAG6); 747 goto dropfrag; 748 } 749 } 750 751 #ifdef MAC 752 mac_ip6q_update(m, q6); 753 #endif 754 755 /* 756 * Stick new segment in its place; check for complete reassembly. 757 * If not complete, check fragment limit. Move to front of packet 758 * queue, as we are the most recently active fragmented packet. 759 */ 760 if (af6 != NULL) 761 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); 762 else 763 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); 764 postinsert: 765 atomic_add_int(&frag6_nfrags, 1); 766 q6->ip6q_nfrag++; 767 768 plen = 0; 769 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 770 if (af6->ip6af_off != plen) { 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 *mp = NULL; 777 return (IPPROTO_DONE); 778 } 779 plen += af6->ip6af_frglen; 780 } 781 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 782 if (af6->ip6af_mff) { 783 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 784 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 785 frag6_freef(q6, bucket); 786 } 787 IP6QB_UNLOCK(bucket); 788 *mp = NULL; 789 return (IPPROTO_DONE); 790 } 791 792 /* Reassembly is complete; concatenate fragments. */ 793 ip6af = TAILQ_FIRST(&q6->ip6q_frags); 794 t = m = ip6af->ip6af_m; 795 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); 796 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 797 m->m_pkthdr.csum_flags &= 798 af6->ip6af_m->m_pkthdr.csum_flags; 799 m->m_pkthdr.csum_data += 800 af6->ip6af_m->m_pkthdr.csum_data; 801 802 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 803 t = m_last(t); 804 m_adj(af6->ip6af_m, af6->ip6af_offset); 805 m_demote_pkthdr(af6->ip6af_m); 806 m_cat(t, af6->ip6af_m); 807 free(af6, M_FRAG6); 808 } 809 810 while (m->m_pkthdr.csum_data & 0xffff0000) 811 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 812 (m->m_pkthdr.csum_data >> 16); 813 814 /* Adjust offset to point where the original next header starts. */ 815 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 816 free(ip6af, M_FRAG6); 817 ip6 = mtod(m, struct ip6_hdr *); 818 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 819 if (q6->ip6q_ecn == IPTOS_ECN_CE) 820 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 821 nxt = q6->ip6q_nxt; 822 823 TAILQ_REMOVE(head, q6, ip6q_tq); 824 V_ip6qb[bucket].count--; 825 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 826 827 ip6_deletefraghdr(m, offset, M_NOWAIT); 828 829 /* Set nxt(-hdr field value) to the original value. */ 830 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 831 (caddr_t)&nxt); 832 833 #ifdef MAC 834 mac_ip6q_reassemble(q6, m); 835 mac_ip6q_destroy(q6); 836 #endif 837 free(q6, M_FRAG6); 838 atomic_subtract_int(&V_frag6_nfragpackets, 1); 839 840 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 841 842 plen = 0; 843 for (t = m; t; t = t->m_next) 844 plen += t->m_len; 845 m->m_pkthdr.len = plen; 846 /* Set a valid receive interface pointer. */ 847 m->m_pkthdr.rcvif = srcifp; 848 } 849 850 #ifdef RSS 851 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 852 M_NOWAIT); 853 if (mtag == NULL) 854 goto dropfrag; 855 856 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 857 ip6dc->ip6dc_nxt = nxt; 858 ip6dc->ip6dc_off = offset; 859 860 m_tag_prepend(m, mtag); 861 #endif 862 863 IP6QB_UNLOCK(bucket); 864 IP6STAT_INC(ip6s_reassembled); 865 in6_ifstat_inc(dstifp, ifs6_reass_ok); 866 867 #ifdef RSS 868 /* Queue/dispatch for reprocessing. */ 869 netisr_dispatch(NETISR_IPV6_DIRECT, m); 870 *mp = NULL; 871 return (IPPROTO_DONE); 872 #endif 873 874 /* Tell launch routine the next header. */ 875 *mp = m; 876 *offp = offset; 877 878 return (nxt); 879 880 dropfrag: 881 IP6QB_UNLOCK(bucket); 882 dropfrag2: 883 in6_ifstat_inc(dstifp, ifs6_reass_fail); 884 IP6STAT_INC(ip6s_fragdropped); 885 m_freem(m); 886 *mp = NULL; 887 return (IPPROTO_DONE); 888 } 889 890 /* 891 * IPv6 reassembling timer processing; 892 * if a timer expires on a reassembly queue, discard it. 893 */ 894 void 895 frag6_slowtimo(void) 896 { 897 VNET_ITERATOR_DECL(vnet_iter); 898 struct ip6qhead *head; 899 struct ip6q *q6, *q6tmp; 900 uint32_t bucket; 901 902 VNET_LIST_RLOCK_NOSLEEP(); 903 VNET_FOREACH(vnet_iter) { 904 CURVNET_SET(vnet_iter); 905 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 906 IP6QB_LOCK(bucket); 907 head = IP6QB_HEAD(bucket); 908 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) 909 if (--q6->ip6q_ttl == 0) { 910 IP6STAT_ADD(ip6s_fragtimeout, 911 q6->ip6q_nfrag); 912 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 913 frag6_freef(q6, bucket); 914 } 915 /* 916 * If we are over the maximum number of fragments 917 * (due to the limit being lowered), drain off 918 * enough to get down to the new limit. 919 * Note that we drain all reassembly queues if 920 * maxfragpackets is 0 (fragmentation is disabled), 921 * and do not enforce a limit when maxfragpackets 922 * is negative. 923 */ 924 while ((V_ip6_maxfragpackets == 0 || 925 (V_ip6_maxfragpackets > 0 && 926 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 927 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { 928 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 929 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 930 frag6_freef(q6, bucket); 931 } 932 IP6QB_UNLOCK(bucket); 933 } 934 /* 935 * If we are still over the maximum number of fragmented 936 * packets, drain off enough to get down to the new limit. 937 */ 938 bucket = 0; 939 while (V_ip6_maxfragpackets >= 0 && 940 atomic_load_int(&V_frag6_nfragpackets) > 941 (u_int)V_ip6_maxfragpackets) { 942 IP6QB_LOCK(bucket); 943 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); 944 if (q6 != NULL) { 945 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 946 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 947 frag6_freef(q6, bucket); 948 } 949 IP6QB_UNLOCK(bucket); 950 bucket = (bucket + 1) % IP6REASS_NHASH; 951 } 952 CURVNET_RESTORE(); 953 } 954 VNET_LIST_RUNLOCK_NOSLEEP(); 955 } 956 957 /* 958 * Eventhandler to adjust limits in case nmbclusters change. 959 */ 960 static void 961 frag6_change(void *tag) 962 { 963 VNET_ITERATOR_DECL(vnet_iter); 964 965 ip6_maxfrags = IP6_MAXFRAGS; 966 VNET_LIST_RLOCK_NOSLEEP(); 967 VNET_FOREACH(vnet_iter) { 968 CURVNET_SET(vnet_iter); 969 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 970 frag6_set_bucketsize(); 971 CURVNET_RESTORE(); 972 } 973 VNET_LIST_RUNLOCK_NOSLEEP(); 974 } 975 976 /* 977 * Initialise reassembly queue and fragment identifier. 978 */ 979 void 980 frag6_init(void) 981 { 982 uint32_t bucket; 983 984 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 985 frag6_set_bucketsize(); 986 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 987 TAILQ_INIT(IP6QB_HEAD(bucket)); 988 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); 989 V_ip6qb[bucket].count = 0; 990 } 991 V_ip6qb_hashseed = arc4random(); 992 V_ip6_maxfragsperpacket = 64; 993 #ifdef VIMAGE 994 V_frag6_on = true; 995 #endif 996 if (!IS_DEFAULT_VNET(curvnet)) 997 return; 998 999 ip6_maxfrags = IP6_MAXFRAGS; 1000 EVENTHANDLER_REGISTER(nmbclusters_change, 1001 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 1002 } 1003 1004 /* 1005 * Drain off all datagram fragments. 1006 */ 1007 static void 1008 frag6_drain_one(void) 1009 { 1010 struct ip6q *q6; 1011 uint32_t bucket; 1012 1013 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1014 IP6QB_LOCK(bucket); 1015 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { 1016 IP6STAT_INC(ip6s_fragdropped); 1017 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 1018 frag6_freef(q6, bucket); 1019 } 1020 IP6QB_UNLOCK(bucket); 1021 } 1022 } 1023 1024 void 1025 frag6_drain(void) 1026 { 1027 VNET_ITERATOR_DECL(vnet_iter); 1028 1029 VNET_LIST_RLOCK_NOSLEEP(); 1030 VNET_FOREACH(vnet_iter) { 1031 CURVNET_SET(vnet_iter); 1032 frag6_drain_one(); 1033 CURVNET_RESTORE(); 1034 } 1035 VNET_LIST_RUNLOCK_NOSLEEP(); 1036 } 1037 1038 #ifdef VIMAGE 1039 /* 1040 * Clear up IPv6 reassembly structures. 1041 */ 1042 void 1043 frag6_destroy(void) 1044 { 1045 uint32_t bucket; 1046 1047 frag6_drain_one(); 1048 V_frag6_on = false; 1049 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1050 KASSERT(V_ip6qb[bucket].count == 0, 1051 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1052 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1053 mtx_destroy(&V_ip6qb[bucket].lock); 1054 } 1055 } 1056 #endif 1057