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sys/netinet6/frag6.c
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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 u_int __exclusive_cache_line frag6_nfrags; 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, &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, 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 if (m->m_len < offset + sizeof(struct ip6_frag)) { 393 m = m_pullup(m, offset + sizeof(struct ip6_frag)); 394 if (m == NULL) { 395 IP6STAT_INC(ip6s_exthdrtoolong); 396 *mp = NULL; 397 return (IPPROTO_DONE); 398 } 399 } 400 ip6 = mtod(m, struct ip6_hdr *); 401 402 dstifp = NULL; 403 /* Find the destination interface of the packet. */ 404 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 405 if (ia6 != NULL) { 406 dstifp = ia6->ia_ifp; 407 ifa_free(&ia6->ia_ifa); 408 } 409 410 /* Jumbo payload cannot contain a fragment header. */ 411 if (ip6->ip6_plen == 0) { 412 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 413 in6_ifstat_inc(dstifp, ifs6_reass_fail); 414 *mp = NULL; 415 return (IPPROTO_DONE); 416 } 417 418 /* 419 * Check whether fragment packet's fragment length is a 420 * multiple of 8 octets (unless it is the last one). 421 * sizeof(struct ip6_frag) == 8 422 * sizeof(struct ip6_hdr) = 40 423 */ 424 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 425 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 426 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 427 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 428 offsetof(struct ip6_hdr, ip6_plen)); 429 in6_ifstat_inc(dstifp, ifs6_reass_fail); 430 *mp = NULL; 431 return (IPPROTO_DONE); 432 } 433 434 IP6STAT_INC(ip6s_fragments); 435 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 436 437 /* 438 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 439 * unrelated to any reassembly. We need to remove the frag hdr 440 * which is ugly. 441 * See RFC 6946 and section 4.5 of RFC 8200. 442 */ 443 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 444 IP6STAT_INC(ip6s_atomicfrags); 445 nxt = ip6f->ip6f_nxt; 446 /* 447 * Set nxt(-hdr field value) to the original value. 448 * We cannot just set ip6->ip6_nxt as there might be 449 * an unfragmentable part with extension headers and 450 * we must update the last one. 451 */ 452 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 453 (caddr_t)&nxt); 454 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - 455 sizeof(struct ip6_frag)); 456 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) 457 goto dropfrag2; 458 m->m_pkthdr.len -= sizeof(struct ip6_frag); 459 in6_ifstat_inc(dstifp, ifs6_reass_ok); 460 *mp = m; 461 return (nxt); 462 } 463 464 /* Offset now points to data portion. */ 465 offset += sizeof(struct ip6_frag); 466 467 /* Get fragment length and discard 0-byte fragments. */ 468 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 469 if (frgpartlen == 0) { 470 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 471 offsetof(struct ip6_hdr, ip6_plen)); 472 in6_ifstat_inc(dstifp, ifs6_reass_fail); 473 IP6STAT_INC(ip6s_fragdropped); 474 *mp = NULL; 475 return (IPPROTO_DONE); 476 } 477 478 /* 479 * Enforce upper bound on number of fragments for the entire system. 480 * If maxfrag is 0, never accept fragments. 481 * If maxfrag is -1, accept all fragments without limitation. 482 */ 483 if (ip6_maxfrags < 0) 484 ; 485 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 486 goto dropfrag2; 487 488 /* 489 * Validate that a full header chain to the ULP is present in the 490 * packet containing the first fragment as per RFC RFC7112 and 491 * RFC 8200 pages 18,19: 492 * The first fragment packet is composed of: 493 * (3) Extension headers, if any, and the Upper-Layer header. These 494 * headers must be in the first fragment. ... 495 */ 496 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 497 /* XXX TODO. thj has D16851 open for this. */ 498 /* Send ICMPv6 4,3 in case of violation. */ 499 500 /* Store receive network interface pointer for later. */ 501 srcifp = m->m_pkthdr.rcvif; 502 503 /* Generate a hash value for fragment bucket selection. */ 504 hashkeyp = hashkey; 505 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 506 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 507 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 508 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 509 *hashkeyp = ip6f->ip6f_ident; 510 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 511 bucket &= IP6REASS_HMASK; 512 IP6QB_LOCK(bucket); 513 head = IP6QB_HEAD(bucket); 514 515 TAILQ_FOREACH(q6, head, ip6q_tq) 516 if (ip6f->ip6f_ident == q6->ip6q_ident && 517 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 518 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 519 #ifdef MAC 520 && mac_ip6q_match(m, q6) 521 #endif 522 ) 523 break; 524 525 only_frag = false; 526 if (q6 == NULL) { 527 528 /* A first fragment to arrive creates a reassembly queue. */ 529 only_frag = true; 530 531 /* 532 * Enforce upper bound on number of fragmented packets 533 * for which we attempt reassembly; 534 * If maxfragpackets is 0, never accept fragments. 535 * If maxfragpackets is -1, accept all fragments without 536 * limitation. 537 */ 538 if (V_ip6_maxfragpackets < 0) 539 ; 540 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 541 atomic_load_int(&V_frag6_nfragpackets) >= 542 (u_int)V_ip6_maxfragpackets) 543 goto dropfrag; 544 545 /* Allocate IPv6 fragement packet queue entry. */ 546 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 547 M_NOWAIT | M_ZERO); 548 if (q6 == NULL) 549 goto dropfrag; 550 #ifdef MAC 551 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 552 free(q6, M_FRAG6); 553 goto dropfrag; 554 } 555 mac_ip6q_create(m, q6); 556 #endif 557 atomic_add_int(&V_frag6_nfragpackets, 1); 558 559 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 560 TAILQ_INIT(&q6->ip6q_frags); 561 q6->ip6q_ident = ip6f->ip6f_ident; 562 q6->ip6q_ttl = IPV6_FRAGTTL; 563 q6->ip6q_src = ip6->ip6_src; 564 q6->ip6q_dst = ip6->ip6_dst; 565 q6->ip6q_ecn = 566 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 567 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 568 569 /* Add the fragemented packet to the bucket. */ 570 TAILQ_INSERT_HEAD(head, q6, ip6q_tq); 571 V_ip6qb[bucket].count++; 572 } 573 574 /* 575 * If it is the 1st fragment, record the length of the 576 * unfragmentable part and the next header of the fragment header. 577 * Assume the first 1st fragement to arrive will be correct. 578 * We do not have any duplicate checks here yet so another packet 579 * with fragoff == 0 could come and overwrite the ip6q_unfrglen 580 * and worse, the next header, at any time. 581 */ 582 if (fragoff == 0 && q6->ip6q_unfrglen == -1) { 583 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 584 sizeof(struct ip6_frag); 585 q6->ip6q_nxt = ip6f->ip6f_nxt; 586 /* XXX ECN? */ 587 } 588 589 /* 590 * Check that the reassembled packet would not exceed 65535 bytes 591 * in size. 592 * If it would exceed, discard the fragment and return an ICMP error. 593 */ 594 if (q6->ip6q_unfrglen >= 0) { 595 /* The 1st fragment has already arrived. */ 596 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 597 if (only_frag) { 598 TAILQ_REMOVE(head, q6, ip6q_tq); 599 V_ip6qb[bucket].count--; 600 atomic_subtract_int(&V_frag6_nfragpackets, 1); 601 #ifdef MAC 602 mac_ip6q_destroy(q6); 603 #endif 604 free(q6, M_FRAG6); 605 } 606 IP6QB_UNLOCK(bucket); 607 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 608 offset - sizeof(struct ip6_frag) + 609 offsetof(struct ip6_frag, ip6f_offlg)); 610 *mp = NULL; 611 return (IPPROTO_DONE); 612 } 613 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 614 if (only_frag) { 615 TAILQ_REMOVE(head, q6, ip6q_tq); 616 V_ip6qb[bucket].count--; 617 atomic_subtract_int(&V_frag6_nfragpackets, 1); 618 #ifdef MAC 619 mac_ip6q_destroy(q6); 620 #endif 621 free(q6, M_FRAG6); 622 } 623 IP6QB_UNLOCK(bucket); 624 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 625 offset - sizeof(struct ip6_frag) + 626 offsetof(struct ip6_frag, ip6f_offlg)); 627 *mp = NULL; 628 return (IPPROTO_DONE); 629 } 630 631 /* 632 * If it is the first fragment, do the above check for each 633 * fragment already stored in the reassembly queue. 634 */ 635 if (fragoff == 0 && !only_frag) { 636 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { 637 638 if (q6->ip6q_unfrglen + af6->ip6af_off + 639 af6->ip6af_frglen > IPV6_MAXPACKET) { 640 struct ip6_hdr *ip6err; 641 struct mbuf *merr; 642 int erroff; 643 644 merr = af6->ip6af_m; 645 erroff = af6->ip6af_offset; 646 647 /* Dequeue the fragment. */ 648 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 649 q6->ip6q_nfrag--; 650 atomic_subtract_int(&frag6_nfrags, 1); 651 free(af6, M_FRAG6); 652 653 /* Set a valid receive interface pointer. */ 654 merr->m_pkthdr.rcvif = srcifp; 655 656 /* Adjust pointer. */ 657 ip6err = mtod(merr, struct ip6_hdr *); 658 659 /* 660 * Restore source and destination addresses 661 * in the erroneous IPv6 header. 662 */ 663 ip6err->ip6_src = q6->ip6q_src; 664 ip6err->ip6_dst = q6->ip6q_dst; 665 666 icmp6_error(merr, ICMP6_PARAM_PROB, 667 ICMP6_PARAMPROB_HEADER, 668 erroff - sizeof(struct ip6_frag) + 669 offsetof(struct ip6_frag, ip6f_offlg)); 670 } 671 } 672 } 673 674 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 675 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 676 M_NOWAIT | M_ZERO); 677 if (ip6af == NULL) 678 goto dropfrag; 679 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; 680 ip6af->ip6af_off = fragoff; 681 ip6af->ip6af_frglen = frgpartlen; 682 ip6af->ip6af_offset = offset; 683 ip6af->ip6af_m = m; 684 685 if (only_frag) { 686 /* 687 * Do a manual insert rather than a hard-to-understand cast 688 * to a different type relying on data structure order to work. 689 */ 690 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); 691 goto postinsert; 692 } 693 694 /* Do duplicate, condition, and boundry checks. */ 695 /* 696 * Handle ECN by comparing this segment with the first one; 697 * if CE is set, do not lose CE. 698 * Drop if CE and not-ECT are mixed for the same packet. 699 */ 700 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 701 ecn0 = q6->ip6q_ecn; 702 if (ecn == IPTOS_ECN_CE) { 703 if (ecn0 == IPTOS_ECN_NOTECT) { 704 free(ip6af, M_FRAG6); 705 goto dropfrag; 706 } 707 if (ecn0 != IPTOS_ECN_CE) 708 q6->ip6q_ecn = IPTOS_ECN_CE; 709 } 710 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 711 free(ip6af, M_FRAG6); 712 goto dropfrag; 713 } 714 715 /* Find a fragmented part which begins after this one does. */ 716 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) 717 if (af6->ip6af_off > ip6af->ip6af_off) 718 break; 719 720 /* 721 * If the incoming framgent overlaps some existing fragments in 722 * the reassembly queue, drop both the new fragment and the 723 * entire reassembly queue. However, if the new fragment 724 * is an exact duplicate of an existing fragment, only silently 725 * drop the existing fragment and leave the fragmentation queue 726 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 727 */ 728 if (af6 != NULL) 729 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); 730 else 731 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 732 if (af6tmp != NULL) { 733 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - 734 ip6af->ip6af_off > 0) { 735 if (af6tmp->ip6af_off != ip6af->ip6af_off || 736 af6tmp->ip6af_frglen != ip6af->ip6af_frglen) 737 frag6_freef(q6, bucket); 738 free(ip6af, M_FRAG6); 739 goto dropfrag; 740 } 741 } 742 if (af6 != NULL) { 743 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 744 af6->ip6af_off > 0) { 745 if (af6->ip6af_off != ip6af->ip6af_off || 746 af6->ip6af_frglen != ip6af->ip6af_frglen) 747 frag6_freef(q6, bucket); 748 free(ip6af, M_FRAG6); 749 goto dropfrag; 750 } 751 } 752 753 #ifdef MAC 754 mac_ip6q_update(m, q6); 755 #endif 756 757 /* 758 * Stick new segment in its place; check for complete reassembly. 759 * If not complete, check fragment limit. Move to front of packet 760 * queue, as we are the most recently active fragmented packet. 761 */ 762 if (af6 != NULL) 763 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); 764 else 765 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); 766 postinsert: 767 atomic_add_int(&frag6_nfrags, 1); 768 q6->ip6q_nfrag++; 769 770 plen = 0; 771 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 772 if (af6->ip6af_off != plen) { 773 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 774 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 775 frag6_freef(q6, bucket); 776 } 777 IP6QB_UNLOCK(bucket); 778 *mp = NULL; 779 return (IPPROTO_DONE); 780 } 781 plen += af6->ip6af_frglen; 782 } 783 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 784 if (af6->ip6af_mff) { 785 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 786 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 787 frag6_freef(q6, bucket); 788 } 789 IP6QB_UNLOCK(bucket); 790 *mp = NULL; 791 return (IPPROTO_DONE); 792 } 793 794 /* Reassembly is complete; concatenate fragments. */ 795 ip6af = TAILQ_FIRST(&q6->ip6q_frags); 796 t = m = ip6af->ip6af_m; 797 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); 798 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 799 m->m_pkthdr.csum_flags &= 800 af6->ip6af_m->m_pkthdr.csum_flags; 801 m->m_pkthdr.csum_data += 802 af6->ip6af_m->m_pkthdr.csum_data; 803 804 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 805 t = m_last(t); 806 m_adj(af6->ip6af_m, af6->ip6af_offset); 807 m_demote_pkthdr(af6->ip6af_m); 808 m_cat(t, af6->ip6af_m); 809 free(af6, M_FRAG6); 810 } 811 812 while (m->m_pkthdr.csum_data & 0xffff0000) 813 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 814 (m->m_pkthdr.csum_data >> 16); 815 816 /* Adjust offset to point where the original next header starts. */ 817 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 818 free(ip6af, M_FRAG6); 819 ip6 = mtod(m, struct ip6_hdr *); 820 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 821 if (q6->ip6q_ecn == IPTOS_ECN_CE) 822 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 823 nxt = q6->ip6q_nxt; 824 825 TAILQ_REMOVE(head, q6, ip6q_tq); 826 V_ip6qb[bucket].count--; 827 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 828 829 ip6_deletefraghdr(m, offset, M_NOWAIT); 830 831 /* Set nxt(-hdr field value) to the original value. */ 832 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 833 (caddr_t)&nxt); 834 835 #ifdef MAC 836 mac_ip6q_reassemble(q6, m); 837 mac_ip6q_destroy(q6); 838 #endif 839 free(q6, M_FRAG6); 840 atomic_subtract_int(&V_frag6_nfragpackets, 1); 841 842 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 843 844 plen = 0; 845 for (t = m; t; t = t->m_next) 846 plen += t->m_len; 847 m->m_pkthdr.len = plen; 848 /* Set a valid receive interface pointer. */ 849 m->m_pkthdr.rcvif = srcifp; 850 } 851 852 #ifdef RSS 853 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 854 M_NOWAIT); 855 if (mtag == NULL) 856 goto dropfrag; 857 858 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 859 ip6dc->ip6dc_nxt = nxt; 860 ip6dc->ip6dc_off = offset; 861 862 m_tag_prepend(m, mtag); 863 #endif 864 865 IP6QB_UNLOCK(bucket); 866 IP6STAT_INC(ip6s_reassembled); 867 in6_ifstat_inc(dstifp, ifs6_reass_ok); 868 869 #ifdef RSS 870 /* Queue/dispatch for reprocessing. */ 871 netisr_dispatch(NETISR_IPV6_DIRECT, m); 872 *mp = NULL; 873 return (IPPROTO_DONE); 874 #endif 875 876 /* Tell launch routine the next header. */ 877 *mp = m; 878 *offp = offset; 879 880 return (nxt); 881 882 dropfrag: 883 IP6QB_UNLOCK(bucket); 884 dropfrag2: 885 in6_ifstat_inc(dstifp, ifs6_reass_fail); 886 IP6STAT_INC(ip6s_fragdropped); 887 m_freem(m); 888 *mp = NULL; 889 return (IPPROTO_DONE); 890 } 891 892 /* 893 * IPv6 reassembling timer processing; 894 * if a timer expires on a reassembly queue, discard it. 895 */ 896 void 897 frag6_slowtimo(void) 898 { 899 VNET_ITERATOR_DECL(vnet_iter); 900 struct ip6qhead *head; 901 struct ip6q *q6, *q6tmp; 902 uint32_t bucket; 903 904 if (atomic_load_int(&frag6_nfrags) == 0) 905 return; 906 907 VNET_LIST_RLOCK_NOSLEEP(); 908 VNET_FOREACH(vnet_iter) { 909 CURVNET_SET(vnet_iter); 910 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 911 if (V_ip6qb[bucket].count == 0) 912 continue; 913 IP6QB_LOCK(bucket); 914 head = IP6QB_HEAD(bucket); 915 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) 916 if (--q6->ip6q_ttl == 0) { 917 IP6STAT_ADD(ip6s_fragtimeout, 918 q6->ip6q_nfrag); 919 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 920 frag6_freef(q6, bucket); 921 } 922 /* 923 * If we are over the maximum number of fragments 924 * (due to the limit being lowered), drain off 925 * enough to get down to the new limit. 926 * Note that we drain all reassembly queues if 927 * maxfragpackets is 0 (fragmentation is disabled), 928 * and do not enforce a limit when maxfragpackets 929 * is negative. 930 */ 931 while ((V_ip6_maxfragpackets == 0 || 932 (V_ip6_maxfragpackets > 0 && 933 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 934 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { 935 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 936 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 937 frag6_freef(q6, bucket); 938 } 939 IP6QB_UNLOCK(bucket); 940 } 941 /* 942 * If we are still over the maximum number of fragmented 943 * packets, drain off enough to get down to the new limit. 944 */ 945 bucket = 0; 946 while (V_ip6_maxfragpackets >= 0 && 947 atomic_load_int(&V_frag6_nfragpackets) > 948 (u_int)V_ip6_maxfragpackets) { 949 IP6QB_LOCK(bucket); 950 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); 951 if (q6 != NULL) { 952 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 953 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 954 frag6_freef(q6, bucket); 955 } 956 IP6QB_UNLOCK(bucket); 957 bucket = (bucket + 1) % IP6REASS_NHASH; 958 } 959 CURVNET_RESTORE(); 960 } 961 VNET_LIST_RUNLOCK_NOSLEEP(); 962 } 963 964 /* 965 * Eventhandler to adjust limits in case nmbclusters change. 966 */ 967 static void 968 frag6_change(void *tag) 969 { 970 VNET_ITERATOR_DECL(vnet_iter); 971 972 ip6_maxfrags = IP6_MAXFRAGS; 973 VNET_LIST_RLOCK_NOSLEEP(); 974 VNET_FOREACH(vnet_iter) { 975 CURVNET_SET(vnet_iter); 976 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 977 frag6_set_bucketsize(); 978 CURVNET_RESTORE(); 979 } 980 VNET_LIST_RUNLOCK_NOSLEEP(); 981 } 982 983 /* 984 * Initialise reassembly queue and fragment identifier. 985 */ 986 void 987 frag6_init(void) 988 { 989 uint32_t bucket; 990 991 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 992 frag6_set_bucketsize(); 993 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 994 TAILQ_INIT(IP6QB_HEAD(bucket)); 995 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); 996 V_ip6qb[bucket].count = 0; 997 } 998 V_ip6qb_hashseed = arc4random(); 999 V_ip6_maxfragsperpacket = 64; 1000 #ifdef VIMAGE 1001 V_frag6_on = true; 1002 #endif 1003 if (!IS_DEFAULT_VNET(curvnet)) 1004 return; 1005 1006 ip6_maxfrags = IP6_MAXFRAGS; 1007 EVENTHANDLER_REGISTER(nmbclusters_change, 1008 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 1009 } 1010 1011 /* 1012 * Drain off all datagram fragments. 1013 */ 1014 static void 1015 frag6_drain_one(void) 1016 { 1017 struct ip6q *q6; 1018 uint32_t bucket; 1019 1020 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1021 IP6QB_LOCK(bucket); 1022 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { 1023 IP6STAT_INC(ip6s_fragdropped); 1024 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 1025 frag6_freef(q6, bucket); 1026 } 1027 IP6QB_UNLOCK(bucket); 1028 } 1029 } 1030 1031 void 1032 frag6_drain(void) 1033 { 1034 VNET_ITERATOR_DECL(vnet_iter); 1035 1036 VNET_LIST_RLOCK_NOSLEEP(); 1037 VNET_FOREACH(vnet_iter) { 1038 CURVNET_SET(vnet_iter); 1039 frag6_drain_one(); 1040 CURVNET_RESTORE(); 1041 } 1042 VNET_LIST_RUNLOCK_NOSLEEP(); 1043 } 1044 1045 #ifdef VIMAGE 1046 /* 1047 * Clear up IPv6 reassembly structures. 1048 */ 1049 void 1050 frag6_destroy(void) 1051 { 1052 uint32_t bucket; 1053 1054 frag6_drain_one(); 1055 V_frag6_on = false; 1056 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1057 KASSERT(V_ip6qb[bucket].count == 0, 1058 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1059 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1060 mtx_destroy(&V_ip6qb[bucket].lock); 1061 } 1062 } 1063 #endif
Cache object: 018f050a140e5678ee6033585d25ef67
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