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/if_private.h> 57 #include <net/netisr.h> 58 #include <net/route.h> 59 #include <net/vnet.h> 60 61 #include <netinet/in.h> 62 #include <netinet/in_var.h> 63 #include <netinet/ip6.h> 64 #include <netinet6/ip6_var.h> 65 #include <netinet/icmp6.h> 66 #include <netinet/in_systm.h> /* For ECN definitions. */ 67 #include <netinet/ip.h> /* For ECN definitions. */ 68 69 #ifdef MAC 70 #include <security/mac/mac_framework.h> 71 #endif 72 73 /* 74 * A "big picture" of how IPv6 fragment queues are all linked together. 75 * 76 * struct ip6qbucket ip6qb[...]; hashed buckets 77 * |||||||| 78 * | 79 * +--- TAILQ(struct ip6q, packets) *q6; tailq entries holding 80 * |||||||| fragmented packets 81 * | (1 per original packet) 82 * | 83 * +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6; tailq entries of IPv6 84 * | *ip6af;fragment packets 85 * | for one original packet 86 * + *mbuf 87 */ 88 89 /* Reassembly headers are stored in hash buckets. */ 90 #define IP6REASS_NHASH_LOG2 10 91 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2) 92 #define IP6REASS_HMASK (IP6REASS_NHASH - 1) 93 94 TAILQ_HEAD(ip6qhead, ip6q); 95 struct ip6qbucket { 96 struct ip6qhead packets; 97 struct mtx lock; 98 int count; 99 }; 100 101 struct ip6asfrag { 102 TAILQ_ENTRY(ip6asfrag) ip6af_tq; 103 struct mbuf *ip6af_m; 104 int ip6af_offset; /* Offset in ip6af_m to next header. */ 105 int ip6af_frglen; /* Fragmentable part length. */ 106 int ip6af_off; /* Fragment offset. */ 107 bool ip6af_mff; /* More fragment bit in frag off. */ 108 }; 109 110 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header"); 111 112 #ifdef VIMAGE 113 /* A flag to indicate if IPv6 fragmentation is initialized. */ 114 VNET_DEFINE_STATIC(bool, frag6_on); 115 #define V_frag6_on VNET(frag6_on) 116 #endif 117 118 /* System wide (global) maximum and count of packets in reassembly queues. */ 119 static int ip6_maxfrags; 120 static u_int __exclusive_cache_line frag6_nfrags; 121 122 /* Maximum and current packets in per-VNET reassembly queue. */ 123 VNET_DEFINE_STATIC(int, ip6_maxfragpackets); 124 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets); 125 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) 126 #define V_frag6_nfragpackets VNET(frag6_nfragpackets) 127 128 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */ 129 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize); 130 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket); 131 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize) 132 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket) 133 134 /* Per-VNET reassembly queue buckets. */ 135 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]); 136 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed); 137 #define V_ip6qb VNET(ip6qb) 138 #define V_ip6qb_hashseed VNET(ip6qb_hashseed) 139 140 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock) 141 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock) 142 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED) 143 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock) 144 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].packets) 145 146 /* 147 * By default, limit the number of IP6 fragments across all reassembly 148 * queues to 1/32 of the total number of mbuf clusters. 149 * 150 * Limit the total number of reassembly queues per VNET to the 151 * IP6 fragment limit, but ensure the limit will not allow any bucket 152 * to grow above 100 items. (The bucket limit is 153 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct 154 * multiplier to reach a 100-item limit.) 155 * The 100-item limit was chosen as brief testing seems to show that 156 * this produces "reasonable" performance on some subset of systems 157 * under DoS attack. 158 */ 159 #define IP6_MAXFRAGS (nmbclusters / 32) 160 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) 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, &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 " 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 | CTLFLAG_NEEDGIANT, 201 NULL, 0, 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 * Remove the IPv6 fragmentation header from the mbuf. 218 */ 219 int 220 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused) 221 { 222 struct ip6_hdr *ip6; 223 224 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag), 225 ("%s: ext headers not contigous in mbuf %p m_len %d >= " 226 "offset %d + %zu\n", __func__, m, m->m_len, offset, 227 sizeof(struct ip6_frag))); 228 229 /* Delete frag6 header. */ 230 ip6 = mtod(m, struct ip6_hdr *); 231 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset); 232 m->m_data += sizeof(struct ip6_frag); 233 m->m_len -= sizeof(struct ip6_frag); 234 m->m_flags |= M_FRAGMENTED; 235 236 return (0); 237 } 238 239 /* 240 * Free a fragment reassembly header and all associated datagrams. 241 */ 242 static void 243 frag6_freef(struct ip6q *q6, uint32_t bucket) 244 { 245 struct ip6_hdr *ip6; 246 struct ip6asfrag *af6; 247 struct mbuf *m; 248 249 IP6QB_LOCK_ASSERT(bucket); 250 251 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 252 m = af6->ip6af_m; 253 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 254 255 /* 256 * Return ICMP time exceeded error for the 1st fragment. 257 * Just free other fragments. 258 */ 259 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { 260 /* Adjust pointer. */ 261 ip6 = mtod(m, struct ip6_hdr *); 262 263 /* Restore source and destination addresses. */ 264 ip6->ip6_src = q6->ip6q_src; 265 ip6->ip6_dst = q6->ip6q_dst; 266 267 icmp6_error(m, ICMP6_TIME_EXCEEDED, 268 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 269 } else 270 m_freem(m); 271 272 free(af6, M_FRAG6); 273 } 274 275 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq); 276 V_ip6qb[bucket].count--; 277 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 278 #ifdef MAC 279 mac_ip6q_destroy(q6); 280 #endif 281 free(q6, M_FRAG6); 282 atomic_subtract_int(&V_frag6_nfragpackets, 1); 283 } 284 285 /* 286 * Drain off all datagram fragments belonging to 287 * the given network interface. 288 */ 289 static void 290 frag6_cleanup(void *arg __unused, struct ifnet *ifp) 291 { 292 struct ip6qhead *head; 293 struct ip6q *q6; 294 struct ip6asfrag *af6; 295 uint32_t bucket; 296 297 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 298 299 CURVNET_SET_QUIET(ifp->if_vnet); 300 #ifdef VIMAGE 301 /* 302 * Skip processing if IPv6 reassembly is not initialised or 303 * torn down by frag6_destroy(). 304 */ 305 if (!V_frag6_on) { 306 CURVNET_RESTORE(); 307 return; 308 } 309 #endif 310 311 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 312 IP6QB_LOCK(bucket); 313 head = IP6QB_HEAD(bucket); 314 /* Scan fragment list. */ 315 TAILQ_FOREACH(q6, head, ip6q_tq) { 316 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 317 /* Clear no longer valid rcvif pointer. */ 318 if (af6->ip6af_m->m_pkthdr.rcvif == ifp) 319 af6->ip6af_m->m_pkthdr.rcvif = NULL; 320 } 321 } 322 IP6QB_UNLOCK(bucket); 323 } 324 CURVNET_RESTORE(); 325 } 326 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); 327 328 /* 329 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 330 * each other, in terms of next header field handling in fragment header. 331 * While the sender will use the same value for all of the fragmented packets, 332 * receiver is suggested not to check for consistency. 333 * 334 * Fragment rules (p18,p19): 335 * (2) A Fragment header containing: 336 * The Next Header value that identifies the first header 337 * after the Per-Fragment headers of the original packet. 338 * -> next header field is same for all fragments 339 * 340 * Reassembly rule (p20): 341 * The Next Header field of the last header of the Per-Fragment 342 * headers is obtained from the Next Header field of the first 343 * fragment's Fragment header. 344 * -> should grab it from the first fragment only 345 * 346 * The following note also contradicts with fragment rule - no one is going to 347 * send different fragment with different next header field. 348 * 349 * Additional note (p22) [not an error]: 350 * The Next Header values in the Fragment headers of different 351 * fragments of the same original packet may differ. Only the value 352 * from the Offset zero fragment packet is used for reassembly. 353 * -> should grab it from the first fragment only 354 * 355 * There is no explicit reason given in the RFC. Historical reason maybe? 356 */ 357 /* 358 * Fragment input. 359 */ 360 int 361 frag6_input(struct mbuf **mp, int *offp, int proto) 362 { 363 struct mbuf *m, *t; 364 struct ip6_hdr *ip6; 365 struct ip6_frag *ip6f; 366 struct ip6qhead *head; 367 struct ip6q *q6; 368 struct ip6asfrag *af6, *ip6af, *af6tmp; 369 struct in6_ifaddr *ia6; 370 struct ifnet *dstifp, *srcifp; 371 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 372 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 373 uint32_t bucket, *hashkeyp; 374 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 375 int nxt, offset, plen; 376 uint8_t ecn, ecn0; 377 bool only_frag; 378 #ifdef RSS 379 struct ip6_direct_ctx *ip6dc; 380 struct m_tag *mtag; 381 #endif 382 383 m = *mp; 384 offset = *offp; 385 386 M_ASSERTPKTHDR(m); 387 388 if (m->m_len < offset + sizeof(struct ip6_frag)) { 389 m = m_pullup(m, offset + sizeof(struct ip6_frag)); 390 if (m == NULL) { 391 IP6STAT_INC(ip6s_exthdrtoolong); 392 *mp = NULL; 393 return (IPPROTO_DONE); 394 } 395 } 396 ip6 = mtod(m, struct ip6_hdr *); 397 398 dstifp = NULL; 399 /* Find the destination interface of the packet. */ 400 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 401 if (ia6 != NULL) 402 dstifp = ia6->ia_ifp; 403 404 /* Jumbo payload cannot contain a fragment header. */ 405 if (ip6->ip6_plen == 0) { 406 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 407 in6_ifstat_inc(dstifp, ifs6_reass_fail); 408 *mp = NULL; 409 return (IPPROTO_DONE); 410 } 411 412 /* 413 * Check whether fragment packet's fragment length is a 414 * multiple of 8 octets (unless it is the last one). 415 * sizeof(struct ip6_frag) == 8 416 * sizeof(struct ip6_hdr) = 40 417 */ 418 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 419 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 420 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 421 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 422 offsetof(struct ip6_hdr, ip6_plen)); 423 in6_ifstat_inc(dstifp, ifs6_reass_fail); 424 *mp = NULL; 425 return (IPPROTO_DONE); 426 } 427 428 IP6STAT_INC(ip6s_fragments); 429 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 430 431 /* 432 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 433 * unrelated to any reassembly. We need to remove the frag hdr 434 * which is ugly. 435 * See RFC 6946 and section 4.5 of RFC 8200. 436 */ 437 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 438 IP6STAT_INC(ip6s_atomicfrags); 439 nxt = ip6f->ip6f_nxt; 440 /* 441 * Set nxt(-hdr field value) to the original value. 442 * We cannot just set ip6->ip6_nxt as there might be 443 * an unfragmentable part with extension headers and 444 * we must update the last one. 445 */ 446 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 447 (caddr_t)&nxt); 448 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - 449 sizeof(struct ip6_frag)); 450 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) 451 goto dropfrag2; 452 m->m_pkthdr.len -= sizeof(struct ip6_frag); 453 in6_ifstat_inc(dstifp, ifs6_reass_ok); 454 *mp = m; 455 return (nxt); 456 } 457 458 /* Offset now points to data portion. */ 459 offset += sizeof(struct ip6_frag); 460 461 /* Get fragment length and discard 0-byte fragments. */ 462 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 463 if (frgpartlen == 0) { 464 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 465 offsetof(struct ip6_hdr, ip6_plen)); 466 in6_ifstat_inc(dstifp, ifs6_reass_fail); 467 IP6STAT_INC(ip6s_fragdropped); 468 *mp = NULL; 469 return (IPPROTO_DONE); 470 } 471 472 /* 473 * Enforce upper bound on number of fragments for the entire system. 474 * If maxfrag is 0, never accept fragments. 475 * If maxfrag is -1, accept all fragments without limitation. 476 */ 477 if (ip6_maxfrags < 0) 478 ; 479 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 480 goto dropfrag2; 481 482 /* 483 * Validate that a full header chain to the ULP is present in the 484 * packet containing the first fragment as per RFC RFC7112 and 485 * RFC 8200 pages 18,19: 486 * The first fragment packet is composed of: 487 * (3) Extension headers, if any, and the Upper-Layer header. These 488 * headers must be in the first fragment. ... 489 */ 490 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 491 /* XXX TODO. thj has D16851 open for this. */ 492 /* Send ICMPv6 4,3 in case of violation. */ 493 494 /* Store receive network interface pointer for later. */ 495 srcifp = m->m_pkthdr.rcvif; 496 497 /* Generate a hash value for fragment bucket selection. */ 498 hashkeyp = hashkey; 499 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 500 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 501 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 502 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 503 *hashkeyp = ip6f->ip6f_ident; 504 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 505 bucket &= IP6REASS_HMASK; 506 IP6QB_LOCK(bucket); 507 head = IP6QB_HEAD(bucket); 508 509 TAILQ_FOREACH(q6, head, ip6q_tq) 510 if (ip6f->ip6f_ident == q6->ip6q_ident && 511 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 512 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 513 #ifdef MAC 514 && mac_ip6q_match(m, q6) 515 #endif 516 ) 517 break; 518 519 only_frag = false; 520 if (q6 == NULL) { 521 /* A first fragment to arrive creates a reassembly queue. */ 522 only_frag = true; 523 524 /* 525 * Enforce upper bound on number of fragmented packets 526 * for which we attempt reassembly; 527 * If maxfragpackets is 0, never accept fragments. 528 * If maxfragpackets is -1, accept all fragments without 529 * limitation. 530 */ 531 if (V_ip6_maxfragpackets < 0) 532 ; 533 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 534 atomic_load_int(&V_frag6_nfragpackets) >= 535 (u_int)V_ip6_maxfragpackets) 536 goto dropfrag; 537 538 /* Allocate IPv6 fragement packet queue entry. */ 539 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 540 M_NOWAIT | M_ZERO); 541 if (q6 == NULL) 542 goto dropfrag; 543 #ifdef MAC 544 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 545 free(q6, M_FRAG6); 546 goto dropfrag; 547 } 548 mac_ip6q_create(m, q6); 549 #endif 550 atomic_add_int(&V_frag6_nfragpackets, 1); 551 552 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 553 TAILQ_INIT(&q6->ip6q_frags); 554 q6->ip6q_ident = ip6f->ip6f_ident; 555 q6->ip6q_ttl = IPV6_FRAGTTL; 556 q6->ip6q_src = ip6->ip6_src; 557 q6->ip6q_dst = ip6->ip6_dst; 558 q6->ip6q_ecn = IPV6_ECN(ip6); 559 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 560 561 /* Add the fragemented packet to the bucket. */ 562 TAILQ_INSERT_HEAD(head, q6, ip6q_tq); 563 V_ip6qb[bucket].count++; 564 } 565 566 /* 567 * If it is the 1st fragment, record the length of the 568 * unfragmentable part and the next header of the fragment header. 569 * Assume the first 1st fragement to arrive will be correct. 570 * We do not have any duplicate checks here yet so another packet 571 * with fragoff == 0 could come and overwrite the ip6q_unfrglen 572 * and worse, the next header, at any time. 573 */ 574 if (fragoff == 0 && q6->ip6q_unfrglen == -1) { 575 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 576 sizeof(struct ip6_frag); 577 q6->ip6q_nxt = ip6f->ip6f_nxt; 578 /* XXX ECN? */ 579 } 580 581 /* 582 * Check that the reassembled packet would not exceed 65535 bytes 583 * in size. 584 * If it would exceed, discard the fragment and return an ICMP error. 585 */ 586 if (q6->ip6q_unfrglen >= 0) { 587 /* The 1st fragment has already arrived. */ 588 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 589 if (only_frag) { 590 TAILQ_REMOVE(head, q6, ip6q_tq); 591 V_ip6qb[bucket].count--; 592 atomic_subtract_int(&V_frag6_nfragpackets, 1); 593 #ifdef MAC 594 mac_ip6q_destroy(q6); 595 #endif 596 free(q6, M_FRAG6); 597 } 598 IP6QB_UNLOCK(bucket); 599 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 600 offset - sizeof(struct ip6_frag) + 601 offsetof(struct ip6_frag, ip6f_offlg)); 602 *mp = NULL; 603 return (IPPROTO_DONE); 604 } 605 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 606 if (only_frag) { 607 TAILQ_REMOVE(head, q6, ip6q_tq); 608 V_ip6qb[bucket].count--; 609 atomic_subtract_int(&V_frag6_nfragpackets, 1); 610 #ifdef MAC 611 mac_ip6q_destroy(q6); 612 #endif 613 free(q6, M_FRAG6); 614 } 615 IP6QB_UNLOCK(bucket); 616 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 617 offset - sizeof(struct ip6_frag) + 618 offsetof(struct ip6_frag, ip6f_offlg)); 619 *mp = NULL; 620 return (IPPROTO_DONE); 621 } 622 623 /* 624 * If it is the first fragment, do the above check for each 625 * fragment already stored in the reassembly queue. 626 */ 627 if (fragoff == 0 && !only_frag) { 628 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { 629 if (q6->ip6q_unfrglen + af6->ip6af_off + 630 af6->ip6af_frglen > IPV6_MAXPACKET) { 631 struct ip6_hdr *ip6err; 632 struct mbuf *merr; 633 int erroff; 634 635 merr = af6->ip6af_m; 636 erroff = af6->ip6af_offset; 637 638 /* Dequeue the fragment. */ 639 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 640 q6->ip6q_nfrag--; 641 atomic_subtract_int(&frag6_nfrags, 1); 642 free(af6, M_FRAG6); 643 644 /* Set a valid receive interface pointer. */ 645 merr->m_pkthdr.rcvif = srcifp; 646 647 /* Adjust pointer. */ 648 ip6err = mtod(merr, struct ip6_hdr *); 649 650 /* 651 * Restore source and destination addresses 652 * in the erroneous IPv6 header. 653 */ 654 ip6err->ip6_src = q6->ip6q_src; 655 ip6err->ip6_dst = q6->ip6q_dst; 656 657 icmp6_error(merr, ICMP6_PARAM_PROB, 658 ICMP6_PARAMPROB_HEADER, 659 erroff - sizeof(struct ip6_frag) + 660 offsetof(struct ip6_frag, ip6f_offlg)); 661 } 662 } 663 } 664 665 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 666 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 667 M_NOWAIT | M_ZERO); 668 if (ip6af == NULL) 669 goto dropfrag; 670 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; 671 ip6af->ip6af_off = fragoff; 672 ip6af->ip6af_frglen = frgpartlen; 673 ip6af->ip6af_offset = offset; 674 ip6af->ip6af_m = m; 675 676 if (only_frag) { 677 /* 678 * Do a manual insert rather than a hard-to-understand cast 679 * to a different type relying on data structure order to work. 680 */ 681 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); 682 goto postinsert; 683 } 684 685 /* Do duplicate, condition, and boundry checks. */ 686 /* 687 * Handle ECN by comparing this segment with the first one; 688 * if CE is set, do not lose CE. 689 * Drop if CE and not-ECT are mixed for the same packet. 690 */ 691 ecn = IPV6_ECN(ip6); 692 ecn0 = q6->ip6q_ecn; 693 if (ecn == IPTOS_ECN_CE) { 694 if (ecn0 == IPTOS_ECN_NOTECT) { 695 free(ip6af, M_FRAG6); 696 goto dropfrag; 697 } 698 if (ecn0 != IPTOS_ECN_CE) 699 q6->ip6q_ecn = IPTOS_ECN_CE; 700 } 701 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 702 free(ip6af, M_FRAG6); 703 goto dropfrag; 704 } 705 706 /* Find a fragmented part which begins after this one does. */ 707 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) 708 if (af6->ip6af_off > ip6af->ip6af_off) 709 break; 710 711 /* 712 * If the incoming framgent overlaps some existing fragments in 713 * the reassembly queue, drop both the new fragment and the 714 * entire reassembly queue. However, if the new fragment 715 * is an exact duplicate of an existing fragment, only silently 716 * drop the existing fragment and leave the fragmentation queue 717 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 718 */ 719 if (af6 != NULL) 720 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); 721 else 722 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 723 if (af6tmp != NULL) { 724 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - 725 ip6af->ip6af_off > 0) { 726 if (af6tmp->ip6af_off != ip6af->ip6af_off || 727 af6tmp->ip6af_frglen != ip6af->ip6af_frglen) 728 frag6_freef(q6, bucket); 729 free(ip6af, M_FRAG6); 730 goto dropfrag; 731 } 732 } 733 if (af6 != NULL) { 734 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 735 af6->ip6af_off > 0) { 736 if (af6->ip6af_off != ip6af->ip6af_off || 737 af6->ip6af_frglen != ip6af->ip6af_frglen) 738 frag6_freef(q6, bucket); 739 free(ip6af, M_FRAG6); 740 goto dropfrag; 741 } 742 } 743 744 #ifdef MAC 745 mac_ip6q_update(m, q6); 746 #endif 747 748 /* 749 * Stick new segment in its place; check for complete reassembly. 750 * If not complete, check fragment limit. Move to front of packet 751 * queue, as we are the most recently active fragmented packet. 752 */ 753 if (af6 != NULL) 754 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); 755 else 756 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); 757 postinsert: 758 atomic_add_int(&frag6_nfrags, 1); 759 q6->ip6q_nfrag++; 760 761 plen = 0; 762 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 763 if (af6->ip6af_off != plen) { 764 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 765 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 766 frag6_freef(q6, bucket); 767 } 768 IP6QB_UNLOCK(bucket); 769 *mp = NULL; 770 return (IPPROTO_DONE); 771 } 772 plen += af6->ip6af_frglen; 773 } 774 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 775 if (af6->ip6af_mff) { 776 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 777 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 778 frag6_freef(q6, bucket); 779 } 780 IP6QB_UNLOCK(bucket); 781 *mp = NULL; 782 return (IPPROTO_DONE); 783 } 784 785 /* Reassembly is complete; concatenate fragments. */ 786 ip6af = TAILQ_FIRST(&q6->ip6q_frags); 787 t = m = ip6af->ip6af_m; 788 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); 789 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 790 m->m_pkthdr.csum_flags &= 791 af6->ip6af_m->m_pkthdr.csum_flags; 792 m->m_pkthdr.csum_data += 793 af6->ip6af_m->m_pkthdr.csum_data; 794 795 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 796 t = m_last(t); 797 m_adj(af6->ip6af_m, af6->ip6af_offset); 798 m_demote_pkthdr(af6->ip6af_m); 799 m_cat(t, af6->ip6af_m); 800 free(af6, M_FRAG6); 801 } 802 803 while (m->m_pkthdr.csum_data & 0xffff0000) 804 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 805 (m->m_pkthdr.csum_data >> 16); 806 807 /* Adjust offset to point where the original next header starts. */ 808 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 809 free(ip6af, M_FRAG6); 810 ip6 = mtod(m, struct ip6_hdr *); 811 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 812 if (q6->ip6q_ecn == IPTOS_ECN_CE) 813 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 814 nxt = q6->ip6q_nxt; 815 816 TAILQ_REMOVE(head, q6, ip6q_tq); 817 V_ip6qb[bucket].count--; 818 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 819 820 ip6_deletefraghdr(m, offset, M_NOWAIT); 821 822 /* Set nxt(-hdr field value) to the original value. */ 823 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 824 (caddr_t)&nxt); 825 826 #ifdef MAC 827 mac_ip6q_reassemble(q6, m); 828 mac_ip6q_destroy(q6); 829 #endif 830 free(q6, M_FRAG6); 831 atomic_subtract_int(&V_frag6_nfragpackets, 1); 832 833 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 834 835 plen = 0; 836 for (t = m; t; t = t->m_next) 837 plen += t->m_len; 838 m->m_pkthdr.len = plen; 839 /* Set a valid receive interface pointer. */ 840 m->m_pkthdr.rcvif = srcifp; 841 } 842 843 #ifdef RSS 844 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 845 M_NOWAIT); 846 if (mtag == NULL) 847 goto dropfrag; 848 849 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 850 ip6dc->ip6dc_nxt = nxt; 851 ip6dc->ip6dc_off = offset; 852 853 m_tag_prepend(m, mtag); 854 #endif 855 856 IP6QB_UNLOCK(bucket); 857 IP6STAT_INC(ip6s_reassembled); 858 in6_ifstat_inc(dstifp, ifs6_reass_ok); 859 860 #ifdef RSS 861 /* Queue/dispatch for reprocessing. */ 862 netisr_dispatch(NETISR_IPV6_DIRECT, m); 863 *mp = NULL; 864 return (IPPROTO_DONE); 865 #endif 866 867 /* Tell launch routine the next header. */ 868 *mp = m; 869 *offp = offset; 870 871 return (nxt); 872 873 dropfrag: 874 IP6QB_UNLOCK(bucket); 875 dropfrag2: 876 in6_ifstat_inc(dstifp, ifs6_reass_fail); 877 IP6STAT_INC(ip6s_fragdropped); 878 m_freem(m); 879 *mp = NULL; 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 static struct callout frag6_callout; 888 static void 889 frag6_slowtimo(void *arg __unused) 890 { 891 VNET_ITERATOR_DECL(vnet_iter); 892 struct ip6qhead *head; 893 struct ip6q *q6, *q6tmp; 894 uint32_t bucket; 895 896 if (atomic_load_int(&frag6_nfrags) == 0) 897 goto done; 898 899 VNET_LIST_RLOCK_NOSLEEP(); 900 VNET_FOREACH(vnet_iter) { 901 CURVNET_SET(vnet_iter); 902 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 903 if (V_ip6qb[bucket].count == 0) 904 continue; 905 IP6QB_LOCK(bucket); 906 head = IP6QB_HEAD(bucket); 907 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) 908 if (--q6->ip6q_ttl == 0) { 909 IP6STAT_ADD(ip6s_fragtimeout, 910 q6->ip6q_nfrag); 911 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 912 frag6_freef(q6, bucket); 913 } 914 /* 915 * If we are over the maximum number of fragments 916 * (due to the limit being lowered), drain off 917 * enough to get down to the new limit. 918 * Note that we drain all reassembly queues if 919 * maxfragpackets is 0 (fragmentation is disabled), 920 * and do not enforce a limit when maxfragpackets 921 * is negative. 922 */ 923 while ((V_ip6_maxfragpackets == 0 || 924 (V_ip6_maxfragpackets > 0 && 925 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 926 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { 927 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 928 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 929 frag6_freef(q6, bucket); 930 } 931 IP6QB_UNLOCK(bucket); 932 } 933 /* 934 * If we are still over the maximum number of fragmented 935 * packets, drain off enough to get down to the new limit. 936 */ 937 bucket = 0; 938 while (V_ip6_maxfragpackets >= 0 && 939 atomic_load_int(&V_frag6_nfragpackets) > 940 (u_int)V_ip6_maxfragpackets) { 941 IP6QB_LOCK(bucket); 942 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); 943 if (q6 != NULL) { 944 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 945 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 946 frag6_freef(q6, bucket); 947 } 948 IP6QB_UNLOCK(bucket); 949 bucket = (bucket + 1) % IP6REASS_NHASH; 950 } 951 CURVNET_RESTORE(); 952 } 953 VNET_LIST_RUNLOCK_NOSLEEP(); 954 done: 955 callout_reset_sbt(&frag6_callout, SBT_1MS * 500, SBT_1MS * 10, 956 frag6_slowtimo, NULL, 0); 957 } 958 959 static void 960 frag6_slowtimo_init(void *arg __unused) 961 { 962 963 callout_init(&frag6_callout, 1); 964 callout_reset_sbt(&frag6_callout, SBT_1MS * 500, SBT_1MS * 10, 965 frag6_slowtimo, NULL, 0); 966 } 967 SYSINIT(frag6, SI_SUB_VNET_DONE, SI_ORDER_ANY, frag6_slowtimo_init, NULL); 968 969 /* 970 * Eventhandler to adjust limits in case nmbclusters change. 971 */ 972 static void 973 frag6_change(void *tag) 974 { 975 VNET_ITERATOR_DECL(vnet_iter); 976 977 ip6_maxfrags = IP6_MAXFRAGS; 978 VNET_LIST_RLOCK_NOSLEEP(); 979 VNET_FOREACH(vnet_iter) { 980 CURVNET_SET(vnet_iter); 981 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 982 frag6_set_bucketsize(); 983 CURVNET_RESTORE(); 984 } 985 VNET_LIST_RUNLOCK_NOSLEEP(); 986 } 987 988 /* 989 * Initialise reassembly queue and fragment identifier. 990 */ 991 void 992 frag6_init(void) 993 { 994 uint32_t bucket; 995 996 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 997 frag6_set_bucketsize(); 998 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 999 TAILQ_INIT(IP6QB_HEAD(bucket)); 1000 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); 1001 V_ip6qb[bucket].count = 0; 1002 } 1003 V_ip6qb_hashseed = arc4random(); 1004 V_ip6_maxfragsperpacket = 64; 1005 #ifdef VIMAGE 1006 V_frag6_on = true; 1007 #endif 1008 if (!IS_DEFAULT_VNET(curvnet)) 1009 return; 1010 1011 ip6_maxfrags = IP6_MAXFRAGS; 1012 EVENTHANDLER_REGISTER(nmbclusters_change, 1013 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 1014 } 1015 1016 /* 1017 * Drain off all datagram fragments. 1018 */ 1019 static void 1020 frag6_drain_one(void) 1021 { 1022 struct ip6q *q6; 1023 uint32_t bucket; 1024 1025 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1026 IP6QB_LOCK(bucket); 1027 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { 1028 IP6STAT_INC(ip6s_fragdropped); 1029 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 1030 frag6_freef(q6, bucket); 1031 } 1032 IP6QB_UNLOCK(bucket); 1033 } 1034 } 1035 1036 void 1037 frag6_drain(void) 1038 { 1039 VNET_ITERATOR_DECL(vnet_iter); 1040 1041 VNET_LIST_RLOCK_NOSLEEP(); 1042 VNET_FOREACH(vnet_iter) { 1043 CURVNET_SET(vnet_iter); 1044 frag6_drain_one(); 1045 CURVNET_RESTORE(); 1046 } 1047 VNET_LIST_RUNLOCK_NOSLEEP(); 1048 } 1049 1050 #ifdef VIMAGE 1051 /* 1052 * Clear up IPv6 reassembly structures. 1053 */ 1054 void 1055 frag6_destroy(void) 1056 { 1057 uint32_t bucket; 1058 1059 frag6_drain_one(); 1060 V_frag6_on = false; 1061 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1062 KASSERT(V_ip6qb[bucket].count == 0, 1063 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1064 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1065 mtx_destroy(&V_ip6qb[bucket].lock); 1066 } 1067 } 1068 #endif 1069