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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 * Sysctls and helper function. 163 */ 164 SYSCTL_DECL(_net_inet6_ip6); 165 166 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags, 167 CTLFLAG_RD, &frag6_nfrags, 0, 168 "Global number of IPv6 fragments across all reassembly queues."); 169 170 static void 171 frag6_set_bucketsize(void) 172 { 173 int i; 174 175 if ((i = V_ip6_maxfragpackets) > 0) 176 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); 177 } 178 179 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, 180 CTLFLAG_RW, &ip6_maxfrags, 0, 181 "Maximum allowed number of outstanding IPv6 packet fragments. " 182 "A value of 0 means no fragmented packets will be accepted, while " 183 "a value of -1 means no limit"); 184 185 static int 186 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS) 187 { 188 int error, val; 189 190 val = V_ip6_maxfragpackets; 191 error = sysctl_handle_int(oidp, &val, 0, req); 192 if (error != 0 || !req->newptr) 193 return (error); 194 V_ip6_maxfragpackets = val; 195 frag6_set_bucketsize(); 196 return (0); 197 } 198 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, 199 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 200 NULL, 0, sysctl_ip6_maxfragpackets, "I", 201 "Default maximum number of outstanding fragmented IPv6 packets. " 202 "A value of 0 means no fragmented packets will be accepted, while a " 203 "a value of -1 means no limit"); 204 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets, 205 CTLFLAG_VNET | CTLFLAG_RD, 206 __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0, 207 "Per-VNET number of IPv6 fragments across all reassembly queues."); 208 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket, 209 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0, 210 "Maximum allowed number of fragments per packet"); 211 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize, 212 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0, 213 "Maximum number of reassembly queues per hash bucket"); 214 215 /* 216 * Remove the IPv6 fragmentation header from the mbuf. 217 */ 218 int 219 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused) 220 { 221 struct ip6_hdr *ip6; 222 223 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag), 224 ("%s: ext headers not contigous in mbuf %p m_len %d >= " 225 "offset %d + %zu\n", __func__, m, m->m_len, offset, 226 sizeof(struct ip6_frag))); 227 228 /* Delete frag6 header. */ 229 ip6 = mtod(m, struct ip6_hdr *); 230 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset); 231 m->m_data += sizeof(struct ip6_frag); 232 m->m_len -= sizeof(struct ip6_frag); 233 m->m_flags |= M_FRAGMENTED; 234 235 return (0); 236 } 237 238 /* 239 * Free a fragment reassembly header and all associated datagrams. 240 */ 241 static void 242 frag6_freef(struct ip6q *q6, uint32_t bucket) 243 { 244 struct ip6_hdr *ip6; 245 struct ip6asfrag *af6; 246 struct mbuf *m; 247 248 IP6QB_LOCK_ASSERT(bucket); 249 250 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 251 m = af6->ip6af_m; 252 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 253 254 /* 255 * Return ICMP time exceeded error for the 1st fragment. 256 * Just free other fragments. 257 */ 258 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { 259 /* Adjust pointer. */ 260 ip6 = mtod(m, struct ip6_hdr *); 261 262 /* Restore source and destination addresses. */ 263 ip6->ip6_src = q6->ip6q_src; 264 ip6->ip6_dst = q6->ip6q_dst; 265 266 icmp6_error(m, ICMP6_TIME_EXCEEDED, 267 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 268 } else 269 m_freem(m); 270 271 free(af6, M_FRAG6); 272 } 273 274 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq); 275 V_ip6qb[bucket].count--; 276 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 277 #ifdef MAC 278 mac_ip6q_destroy(q6); 279 #endif 280 free(q6, M_FRAG6); 281 atomic_subtract_int(&V_frag6_nfragpackets, 1); 282 } 283 284 /* 285 * Drain off all datagram fragments belonging to 286 * the given network interface. 287 */ 288 static void 289 frag6_cleanup(void *arg __unused, struct ifnet *ifp) 290 { 291 struct ip6qhead *head; 292 struct ip6q *q6; 293 struct ip6asfrag *af6; 294 uint32_t bucket; 295 296 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 297 298 CURVNET_SET_QUIET(ifp->if_vnet); 299 #ifdef VIMAGE 300 /* 301 * Skip processing if IPv6 reassembly is not initialised or 302 * torn down by frag6_destroy(). 303 */ 304 if (!V_frag6_on) { 305 CURVNET_RESTORE(); 306 return; 307 } 308 #endif 309 310 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 311 IP6QB_LOCK(bucket); 312 head = IP6QB_HEAD(bucket); 313 /* Scan fragment list. */ 314 TAILQ_FOREACH(q6, head, ip6q_tq) { 315 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 316 /* Clear no longer valid rcvif pointer. */ 317 if (af6->ip6af_m->m_pkthdr.rcvif == ifp) 318 af6->ip6af_m->m_pkthdr.rcvif = NULL; 319 } 320 } 321 IP6QB_UNLOCK(bucket); 322 } 323 CURVNET_RESTORE(); 324 } 325 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); 326 327 /* 328 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 329 * each other, in terms of next header field handling in fragment header. 330 * While the sender will use the same value for all of the fragmented packets, 331 * receiver is suggested not to check for consistency. 332 * 333 * Fragment rules (p18,p19): 334 * (2) A Fragment header containing: 335 * The Next Header value that identifies the first header 336 * after the Per-Fragment headers of the original packet. 337 * -> next header field is same for all fragments 338 * 339 * Reassembly rule (p20): 340 * The Next Header field of the last header of the Per-Fragment 341 * headers is obtained from the Next Header field of the first 342 * fragment's Fragment header. 343 * -> should grab it from the first fragment only 344 * 345 * The following note also contradicts with fragment rule - no one is going to 346 * send different fragment with different next header field. 347 * 348 * Additional note (p22) [not an error]: 349 * The Next Header values in the Fragment headers of different 350 * fragments of the same original packet may differ. Only the value 351 * from the Offset zero fragment packet is used for reassembly. 352 * -> should grab it from the first fragment only 353 * 354 * There is no explicit reason given in the RFC. Historical reason maybe? 355 */ 356 /* 357 * Fragment input. 358 */ 359 int 360 frag6_input(struct mbuf **mp, int *offp, int proto) 361 { 362 struct mbuf *m, *t; 363 struct ip6_hdr *ip6; 364 struct ip6_frag *ip6f; 365 struct ip6qhead *head; 366 struct ip6q *q6; 367 struct ip6asfrag *af6, *ip6af, *af6tmp; 368 struct in6_ifaddr *ia6; 369 struct ifnet *dstifp, *srcifp; 370 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 371 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 372 uint32_t bucket, *hashkeyp; 373 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 374 int nxt, offset, plen; 375 uint8_t ecn, ecn0; 376 bool only_frag; 377 #ifdef RSS 378 struct ip6_direct_ctx *ip6dc; 379 struct m_tag *mtag; 380 #endif 381 382 m = *mp; 383 offset = *offp; 384 385 M_ASSERTPKTHDR(m); 386 387 if (m->m_len < offset + sizeof(struct ip6_frag)) { 388 m = m_pullup(m, offset + sizeof(struct ip6_frag)); 389 if (m == NULL) { 390 IP6STAT_INC(ip6s_exthdrtoolong); 391 *mp = NULL; 392 return (IPPROTO_DONE); 393 } 394 } 395 ip6 = mtod(m, struct ip6_hdr *); 396 397 dstifp = NULL; 398 /* Find the destination interface of the packet. */ 399 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 400 if (ia6 != NULL) 401 dstifp = ia6->ia_ifp; 402 403 /* Jumbo payload cannot contain a fragment header. */ 404 if (ip6->ip6_plen == 0) { 405 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 406 in6_ifstat_inc(dstifp, ifs6_reass_fail); 407 *mp = NULL; 408 return (IPPROTO_DONE); 409 } 410 411 /* 412 * Check whether fragment packet's fragment length is a 413 * multiple of 8 octets (unless it is the last one). 414 * sizeof(struct ip6_frag) == 8 415 * sizeof(struct ip6_hdr) = 40 416 */ 417 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 418 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 419 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 420 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 421 offsetof(struct ip6_hdr, ip6_plen)); 422 in6_ifstat_inc(dstifp, ifs6_reass_fail); 423 *mp = NULL; 424 return (IPPROTO_DONE); 425 } 426 427 IP6STAT_INC(ip6s_fragments); 428 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 429 430 /* 431 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 432 * unrelated to any reassembly. We need to remove the frag hdr 433 * which is ugly. 434 * See RFC 6946 and section 4.5 of RFC 8200. 435 */ 436 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 437 IP6STAT_INC(ip6s_atomicfrags); 438 nxt = ip6f->ip6f_nxt; 439 /* 440 * Set nxt(-hdr field value) to the original value. 441 * We cannot just set ip6->ip6_nxt as there might be 442 * an unfragmentable part with extension headers and 443 * we must update the last one. 444 */ 445 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 446 (caddr_t)&nxt); 447 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - 448 sizeof(struct ip6_frag)); 449 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) 450 goto dropfrag2; 451 m->m_pkthdr.len -= sizeof(struct ip6_frag); 452 in6_ifstat_inc(dstifp, ifs6_reass_ok); 453 *mp = m; 454 return (nxt); 455 } 456 457 /* Offset now points to data portion. */ 458 offset += sizeof(struct ip6_frag); 459 460 /* Get fragment length and discard 0-byte fragments. */ 461 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 462 if (frgpartlen == 0) { 463 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 464 offsetof(struct ip6_hdr, ip6_plen)); 465 in6_ifstat_inc(dstifp, ifs6_reass_fail); 466 IP6STAT_INC(ip6s_fragdropped); 467 *mp = NULL; 468 return (IPPROTO_DONE); 469 } 470 471 /* 472 * Enforce upper bound on number of fragments for the entire system. 473 * If maxfrag is 0, never accept fragments. 474 * If maxfrag is -1, accept all fragments without limitation. 475 */ 476 if (ip6_maxfrags < 0) 477 ; 478 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 479 goto dropfrag2; 480 481 /* 482 * Validate that a full header chain to the ULP is present in the 483 * packet containing the first fragment as per RFC RFC7112 and 484 * RFC 8200 pages 18,19: 485 * The first fragment packet is composed of: 486 * (3) Extension headers, if any, and the Upper-Layer header. These 487 * headers must be in the first fragment. ... 488 */ 489 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 490 /* XXX TODO. thj has D16851 open for this. */ 491 /* Send ICMPv6 4,3 in case of violation. */ 492 493 /* Store receive network interface pointer for later. */ 494 srcifp = m->m_pkthdr.rcvif; 495 496 /* Generate a hash value for fragment bucket selection. */ 497 hashkeyp = hashkey; 498 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 499 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 500 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 501 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 502 *hashkeyp = ip6f->ip6f_ident; 503 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 504 bucket &= IP6REASS_HMASK; 505 IP6QB_LOCK(bucket); 506 head = IP6QB_HEAD(bucket); 507 508 TAILQ_FOREACH(q6, head, ip6q_tq) 509 if (ip6f->ip6f_ident == q6->ip6q_ident && 510 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 511 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 512 #ifdef MAC 513 && mac_ip6q_match(m, q6) 514 #endif 515 ) 516 break; 517 518 only_frag = false; 519 if (q6 == NULL) { 520 /* A first fragment to arrive creates a reassembly queue. */ 521 only_frag = true; 522 523 /* 524 * Enforce upper bound on number of fragmented packets 525 * for which we attempt reassembly; 526 * If maxfragpackets is 0, never accept fragments. 527 * If maxfragpackets is -1, accept all fragments without 528 * limitation. 529 */ 530 if (V_ip6_maxfragpackets < 0) 531 ; 532 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 533 atomic_load_int(&V_frag6_nfragpackets) >= 534 (u_int)V_ip6_maxfragpackets) 535 goto dropfrag; 536 537 /* Allocate IPv6 fragement packet queue entry. */ 538 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 539 M_NOWAIT | M_ZERO); 540 if (q6 == NULL) 541 goto dropfrag; 542 #ifdef MAC 543 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 544 free(q6, M_FRAG6); 545 goto dropfrag; 546 } 547 mac_ip6q_create(m, q6); 548 #endif 549 atomic_add_int(&V_frag6_nfragpackets, 1); 550 551 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 552 TAILQ_INIT(&q6->ip6q_frags); 553 q6->ip6q_ident = ip6f->ip6f_ident; 554 q6->ip6q_ttl = IPV6_FRAGTTL; 555 q6->ip6q_src = ip6->ip6_src; 556 q6->ip6q_dst = ip6->ip6_dst; 557 q6->ip6q_ecn = IPV6_ECN(ip6); 558 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 559 560 /* Add the fragemented packet to the bucket. */ 561 TAILQ_INSERT_HEAD(head, q6, ip6q_tq); 562 V_ip6qb[bucket].count++; 563 } 564 565 /* 566 * If it is the 1st fragment, record the length of the 567 * unfragmentable part and the next header of the fragment header. 568 * Assume the first 1st fragement to arrive will be correct. 569 * We do not have any duplicate checks here yet so another packet 570 * with fragoff == 0 could come and overwrite the ip6q_unfrglen 571 * and worse, the next header, at any time. 572 */ 573 if (fragoff == 0 && q6->ip6q_unfrglen == -1) { 574 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 575 sizeof(struct ip6_frag); 576 q6->ip6q_nxt = ip6f->ip6f_nxt; 577 /* XXX ECN? */ 578 } 579 580 /* 581 * Check that the reassembled packet would not exceed 65535 bytes 582 * in size. 583 * If it would exceed, discard the fragment and return an ICMP error. 584 */ 585 if (q6->ip6q_unfrglen >= 0) { 586 /* The 1st fragment has already arrived. */ 587 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 588 if (only_frag) { 589 TAILQ_REMOVE(head, q6, ip6q_tq); 590 V_ip6qb[bucket].count--; 591 atomic_subtract_int(&V_frag6_nfragpackets, 1); 592 #ifdef MAC 593 mac_ip6q_destroy(q6); 594 #endif 595 free(q6, M_FRAG6); 596 } 597 IP6QB_UNLOCK(bucket); 598 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 599 offset - sizeof(struct ip6_frag) + 600 offsetof(struct ip6_frag, ip6f_offlg)); 601 *mp = NULL; 602 return (IPPROTO_DONE); 603 } 604 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 605 if (only_frag) { 606 TAILQ_REMOVE(head, q6, ip6q_tq); 607 V_ip6qb[bucket].count--; 608 atomic_subtract_int(&V_frag6_nfragpackets, 1); 609 #ifdef MAC 610 mac_ip6q_destroy(q6); 611 #endif 612 free(q6, M_FRAG6); 613 } 614 IP6QB_UNLOCK(bucket); 615 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 616 offset - sizeof(struct ip6_frag) + 617 offsetof(struct ip6_frag, ip6f_offlg)); 618 *mp = NULL; 619 return (IPPROTO_DONE); 620 } 621 622 /* 623 * If it is the first fragment, do the above check for each 624 * fragment already stored in the reassembly queue. 625 */ 626 if (fragoff == 0 && !only_frag) { 627 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { 628 if (q6->ip6q_unfrglen + af6->ip6af_off + 629 af6->ip6af_frglen > IPV6_MAXPACKET) { 630 struct ip6_hdr *ip6err; 631 struct mbuf *merr; 632 int erroff; 633 634 merr = af6->ip6af_m; 635 erroff = af6->ip6af_offset; 636 637 /* Dequeue the fragment. */ 638 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 639 q6->ip6q_nfrag--; 640 atomic_subtract_int(&frag6_nfrags, 1); 641 free(af6, M_FRAG6); 642 643 /* Set a valid receive interface pointer. */ 644 merr->m_pkthdr.rcvif = srcifp; 645 646 /* Adjust pointer. */ 647 ip6err = mtod(merr, struct ip6_hdr *); 648 649 /* 650 * Restore source and destination addresses 651 * in the erroneous IPv6 header. 652 */ 653 ip6err->ip6_src = q6->ip6q_src; 654 ip6err->ip6_dst = q6->ip6q_dst; 655 656 icmp6_error(merr, ICMP6_PARAM_PROB, 657 ICMP6_PARAMPROB_HEADER, 658 erroff - sizeof(struct ip6_frag) + 659 offsetof(struct ip6_frag, ip6f_offlg)); 660 } 661 } 662 } 663 664 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 665 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 666 M_NOWAIT | M_ZERO); 667 if (ip6af == NULL) 668 goto dropfrag; 669 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; 670 ip6af->ip6af_off = fragoff; 671 ip6af->ip6af_frglen = frgpartlen; 672 ip6af->ip6af_offset = offset; 673 ip6af->ip6af_m = m; 674 675 if (only_frag) { 676 /* 677 * Do a manual insert rather than a hard-to-understand cast 678 * to a different type relying on data structure order to work. 679 */ 680 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); 681 goto postinsert; 682 } 683 684 /* Do duplicate, condition, and boundry checks. */ 685 /* 686 * Handle ECN by comparing this segment with the first one; 687 * if CE is set, do not lose CE. 688 * Drop if CE and not-ECT are mixed for the same packet. 689 */ 690 ecn = IPV6_ECN(ip6); 691 ecn0 = q6->ip6q_ecn; 692 if (ecn == IPTOS_ECN_CE) { 693 if (ecn0 == IPTOS_ECN_NOTECT) { 694 free(ip6af, M_FRAG6); 695 goto dropfrag; 696 } 697 if (ecn0 != IPTOS_ECN_CE) 698 q6->ip6q_ecn = IPTOS_ECN_CE; 699 } 700 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 701 free(ip6af, M_FRAG6); 702 goto dropfrag; 703 } 704 705 /* Find a fragmented part which begins after this one does. */ 706 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) 707 if (af6->ip6af_off > ip6af->ip6af_off) 708 break; 709 710 /* 711 * If the incoming framgent overlaps some existing fragments in 712 * the reassembly queue, drop both the new fragment and the 713 * entire reassembly queue. However, if the new fragment 714 * is an exact duplicate of an existing fragment, only silently 715 * drop the existing fragment and leave the fragmentation queue 716 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 717 */ 718 if (af6 != NULL) 719 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); 720 else 721 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 722 if (af6tmp != NULL) { 723 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - 724 ip6af->ip6af_off > 0) { 725 if (af6tmp->ip6af_off != ip6af->ip6af_off || 726 af6tmp->ip6af_frglen != ip6af->ip6af_frglen) 727 frag6_freef(q6, bucket); 728 free(ip6af, M_FRAG6); 729 goto dropfrag; 730 } 731 } 732 if (af6 != NULL) { 733 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 734 af6->ip6af_off > 0) { 735 if (af6->ip6af_off != ip6af->ip6af_off || 736 af6->ip6af_frglen != ip6af->ip6af_frglen) 737 frag6_freef(q6, bucket); 738 free(ip6af, M_FRAG6); 739 goto dropfrag; 740 } 741 } 742 743 #ifdef MAC 744 mac_ip6q_update(m, q6); 745 #endif 746 747 /* 748 * Stick new segment in its place; check for complete reassembly. 749 * If not complete, check fragment limit. Move to front of packet 750 * queue, as we are the most recently active fragmented packet. 751 */ 752 if (af6 != NULL) 753 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); 754 else 755 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); 756 postinsert: 757 atomic_add_int(&frag6_nfrags, 1); 758 q6->ip6q_nfrag++; 759 760 plen = 0; 761 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { 762 if (af6->ip6af_off != plen) { 763 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 764 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 765 frag6_freef(q6, bucket); 766 } 767 IP6QB_UNLOCK(bucket); 768 *mp = NULL; 769 return (IPPROTO_DONE); 770 } 771 plen += af6->ip6af_frglen; 772 } 773 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); 774 if (af6->ip6af_mff) { 775 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 776 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 777 frag6_freef(q6, bucket); 778 } 779 IP6QB_UNLOCK(bucket); 780 *mp = NULL; 781 return (IPPROTO_DONE); 782 } 783 784 /* Reassembly is complete; concatenate fragments. */ 785 ip6af = TAILQ_FIRST(&q6->ip6q_frags); 786 t = m = ip6af->ip6af_m; 787 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); 788 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { 789 m->m_pkthdr.csum_flags &= 790 af6->ip6af_m->m_pkthdr.csum_flags; 791 m->m_pkthdr.csum_data += 792 af6->ip6af_m->m_pkthdr.csum_data; 793 794 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); 795 t = m_last(t); 796 m_adj(af6->ip6af_m, af6->ip6af_offset); 797 m_demote_pkthdr(af6->ip6af_m); 798 m_cat(t, af6->ip6af_m); 799 free(af6, M_FRAG6); 800 } 801 802 while (m->m_pkthdr.csum_data & 0xffff0000) 803 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 804 (m->m_pkthdr.csum_data >> 16); 805 806 /* Adjust offset to point where the original next header starts. */ 807 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 808 free(ip6af, M_FRAG6); 809 ip6 = mtod(m, struct ip6_hdr *); 810 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 811 if (q6->ip6q_ecn == IPTOS_ECN_CE) 812 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 813 nxt = q6->ip6q_nxt; 814 815 TAILQ_REMOVE(head, q6, ip6q_tq); 816 V_ip6qb[bucket].count--; 817 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 818 819 ip6_deletefraghdr(m, offset, M_NOWAIT); 820 821 /* Set nxt(-hdr field value) to the original value. */ 822 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 823 (caddr_t)&nxt); 824 825 #ifdef MAC 826 mac_ip6q_reassemble(q6, m); 827 mac_ip6q_destroy(q6); 828 #endif 829 free(q6, M_FRAG6); 830 atomic_subtract_int(&V_frag6_nfragpackets, 1); 831 832 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 833 834 plen = 0; 835 for (t = m; t; t = t->m_next) 836 plen += t->m_len; 837 m->m_pkthdr.len = plen; 838 /* Set a valid receive interface pointer. */ 839 m->m_pkthdr.rcvif = srcifp; 840 } 841 842 #ifdef RSS 843 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 844 M_NOWAIT); 845 if (mtag == NULL) 846 goto dropfrag; 847 848 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 849 ip6dc->ip6dc_nxt = nxt; 850 ip6dc->ip6dc_off = offset; 851 852 m_tag_prepend(m, mtag); 853 #endif 854 855 IP6QB_UNLOCK(bucket); 856 IP6STAT_INC(ip6s_reassembled); 857 in6_ifstat_inc(dstifp, ifs6_reass_ok); 858 859 #ifdef RSS 860 /* Queue/dispatch for reprocessing. */ 861 netisr_dispatch(NETISR_IPV6_DIRECT, m); 862 *mp = NULL; 863 return (IPPROTO_DONE); 864 #endif 865 866 /* Tell launch routine the next header. */ 867 *mp = m; 868 *offp = offset; 869 870 return (nxt); 871 872 dropfrag: 873 IP6QB_UNLOCK(bucket); 874 dropfrag2: 875 in6_ifstat_inc(dstifp, ifs6_reass_fail); 876 IP6STAT_INC(ip6s_fragdropped); 877 m_freem(m); 878 *mp = NULL; 879 return (IPPROTO_DONE); 880 } 881 882 /* 883 * IPv6 reassembling timer processing; 884 * if a timer expires on a reassembly queue, discard it. 885 */ 886 void 887 frag6_slowtimo(void) 888 { 889 VNET_ITERATOR_DECL(vnet_iter); 890 struct ip6qhead *head; 891 struct ip6q *q6, *q6tmp; 892 uint32_t bucket; 893 894 if (atomic_load_int(&frag6_nfrags) == 0) 895 return; 896 897 VNET_LIST_RLOCK_NOSLEEP(); 898 VNET_FOREACH(vnet_iter) { 899 CURVNET_SET(vnet_iter); 900 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 901 if (V_ip6qb[bucket].count == 0) 902 continue; 903 IP6QB_LOCK(bucket); 904 head = IP6QB_HEAD(bucket); 905 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) 906 if (--q6->ip6q_ttl == 0) { 907 IP6STAT_ADD(ip6s_fragtimeout, 908 q6->ip6q_nfrag); 909 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 910 frag6_freef(q6, bucket); 911 } 912 /* 913 * If we are over the maximum number of fragments 914 * (due to the limit being lowered), drain off 915 * enough to get down to the new limit. 916 * Note that we drain all reassembly queues if 917 * maxfragpackets is 0 (fragmentation is disabled), 918 * and do not enforce a limit when maxfragpackets 919 * is negative. 920 */ 921 while ((V_ip6_maxfragpackets == 0 || 922 (V_ip6_maxfragpackets > 0 && 923 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 924 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { 925 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 926 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 927 frag6_freef(q6, bucket); 928 } 929 IP6QB_UNLOCK(bucket); 930 } 931 /* 932 * If we are still over the maximum number of fragmented 933 * packets, drain off enough to get down to the new limit. 934 */ 935 bucket = 0; 936 while (V_ip6_maxfragpackets >= 0 && 937 atomic_load_int(&V_frag6_nfragpackets) > 938 (u_int)V_ip6_maxfragpackets) { 939 IP6QB_LOCK(bucket); 940 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); 941 if (q6 != NULL) { 942 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); 943 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 944 frag6_freef(q6, bucket); 945 } 946 IP6QB_UNLOCK(bucket); 947 bucket = (bucket + 1) % IP6REASS_NHASH; 948 } 949 CURVNET_RESTORE(); 950 } 951 VNET_LIST_RUNLOCK_NOSLEEP(); 952 } 953 954 /* 955 * Eventhandler to adjust limits in case nmbclusters change. 956 */ 957 static void 958 frag6_change(void *tag) 959 { 960 VNET_ITERATOR_DECL(vnet_iter); 961 962 ip6_maxfrags = IP6_MAXFRAGS; 963 VNET_LIST_RLOCK_NOSLEEP(); 964 VNET_FOREACH(vnet_iter) { 965 CURVNET_SET(vnet_iter); 966 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 967 frag6_set_bucketsize(); 968 CURVNET_RESTORE(); 969 } 970 VNET_LIST_RUNLOCK_NOSLEEP(); 971 } 972 973 /* 974 * Initialise reassembly queue and fragment identifier. 975 */ 976 void 977 frag6_init(void) 978 { 979 uint32_t bucket; 980 981 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 982 frag6_set_bucketsize(); 983 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 984 TAILQ_INIT(IP6QB_HEAD(bucket)); 985 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); 986 V_ip6qb[bucket].count = 0; 987 } 988 V_ip6qb_hashseed = arc4random(); 989 V_ip6_maxfragsperpacket = 64; 990 #ifdef VIMAGE 991 V_frag6_on = true; 992 #endif 993 if (!IS_DEFAULT_VNET(curvnet)) 994 return; 995 996 ip6_maxfrags = IP6_MAXFRAGS; 997 EVENTHANDLER_REGISTER(nmbclusters_change, 998 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 999 } 1000 1001 /* 1002 * Drain off all datagram fragments. 1003 */ 1004 static void 1005 frag6_drain_one(void) 1006 { 1007 struct ip6q *q6; 1008 uint32_t bucket; 1009 1010 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1011 IP6QB_LOCK(bucket); 1012 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { 1013 IP6STAT_INC(ip6s_fragdropped); 1014 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 1015 frag6_freef(q6, bucket); 1016 } 1017 IP6QB_UNLOCK(bucket); 1018 } 1019 } 1020 1021 void 1022 frag6_drain(void) 1023 { 1024 VNET_ITERATOR_DECL(vnet_iter); 1025 1026 VNET_LIST_RLOCK_NOSLEEP(); 1027 VNET_FOREACH(vnet_iter) { 1028 CURVNET_SET(vnet_iter); 1029 frag6_drain_one(); 1030 CURVNET_RESTORE(); 1031 } 1032 VNET_LIST_RUNLOCK_NOSLEEP(); 1033 } 1034 1035 #ifdef VIMAGE 1036 /* 1037 * Clear up IPv6 reassembly structures. 1038 */ 1039 void 1040 frag6_destroy(void) 1041 { 1042 uint32_t bucket; 1043 1044 frag6_drain_one(); 1045 V_frag6_on = false; 1046 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1047 KASSERT(V_ip6qb[bucket].count == 0, 1048 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1049 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1050 mtx_destroy(&V_ip6qb[bucket].lock); 1051 } 1052 } 1053 #endif
Cache object: 54ef5f708be83041679b1dda72b0285f
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