1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_rss.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/domain.h> 42 #include <sys/eventhandler.h> 43 #include <sys/hash.h> 44 #include <sys/kernel.h> 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/protosw.h> 48 #include <sys/socket.h> 49 #include <sys/sysctl.h> 50 #include <sys/syslog.h> 51 52 #include <net/if.h> 53 #include <net/if_var.h> 54 #include <net/netisr.h> 55 #include <net/route.h> 56 #include <net/vnet.h> 57 58 #include <netinet/in.h> 59 #include <netinet/in_var.h> 60 #include <netinet/ip6.h> 61 #include <netinet6/ip6_var.h> 62 #include <netinet/icmp6.h> 63 #include <netinet/in_systm.h> /* For ECN definitions. */ 64 #include <netinet/ip.h> /* For ECN definitions. */ 65 66 #ifdef MAC 67 #include <security/mac/mac_framework.h> 68 #endif 69 70 /* Reassembly headers are stored in hash buckets. */ 71 #define IP6REASS_NHASH_LOG2 10 72 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2) 73 #define IP6REASS_HMASK (IP6REASS_NHASH - 1) 74 75 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *, 76 uint32_t bucket __unused); 77 static void frag6_deq(struct ip6asfrag *, uint32_t bucket __unused); 78 static void frag6_insque_head(struct ip6q *, struct ip6q *, 79 uint32_t bucket); 80 static void frag6_remque(struct ip6q *, uint32_t bucket); 81 static void frag6_freef(struct ip6q *, uint32_t bucket); 82 83 struct ip6qbucket { 84 struct ip6q ip6q; 85 struct mtx lock; 86 int count; 87 }; 88 89 struct ip6asfrag { 90 struct ip6asfrag *ip6af_down; 91 struct ip6asfrag *ip6af_up; 92 struct mbuf *ip6af_m; 93 int ip6af_offset; /* offset in ip6af_m to next header */ 94 int ip6af_frglen; /* fragmentable part length */ 95 int ip6af_off; /* fragment offset */ 96 u_int16_t ip6af_mff; /* more fragment bit in frag off */ 97 }; 98 99 #define IP6_REASS_MBUF(ip6af) (*(struct mbuf **)&((ip6af)->ip6af_m)) 100 101 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header"); 102 103 /* System wide (global) maximum and count of packets in reassembly queues. */ 104 static int ip6_maxfrags; 105 static volatile u_int frag6_nfrags = 0; 106 107 /* Maximum and current packets in per-VNET reassembly queue. */ 108 VNET_DEFINE_STATIC(int, ip6_maxfragpackets); 109 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets); 110 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) 111 #define V_frag6_nfragpackets VNET(frag6_nfragpackets) 112 113 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */ 114 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize); 115 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket); 116 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize) 117 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket) 118 119 /* Per-VNET reassembly queue buckets. */ 120 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]); 121 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed); 122 #define V_ip6qb VNET(ip6qb) 123 #define V_ip6qb_hashseed VNET(ip6qb_hashseed) 124 125 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock) 126 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock) 127 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED) 128 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock) 129 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].ip6q) 130 131 /* 132 * By default, limit the number of IP6 fragments across all reassembly 133 * queues to 1/32 of the total number of mbuf clusters. 134 * 135 * Limit the total number of reassembly queues per VNET to the 136 * IP6 fragment limit, but ensure the limit will not allow any bucket 137 * to grow above 100 items. (The bucket limit is 138 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct 139 * multiplier to reach a 100-item limit.) 140 * The 100-item limit was chosen as brief testing seems to show that 141 * this produces "reasonable" performance on some subset of systems 142 * under DoS attack. 143 */ 144 #define IP6_MAXFRAGS (nmbclusters / 32) 145 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) 146 147 148 /* 149 * Sysctls and helper function. 150 */ 151 SYSCTL_DECL(_net_inet6_ip6); 152 153 static void 154 frag6_set_bucketsize(void) 155 { 156 int i; 157 158 if ((i = V_ip6_maxfragpackets) > 0) 159 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); 160 } 161 162 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, 163 CTLFLAG_RW, &ip6_maxfrags, 0, 164 "Maximum allowed number of outstanding IPv6 packet fragments. " 165 "A value of 0 means no fragmented packets will be accepted, while a " 166 "a value of -1 means no limit"); 167 168 static int 169 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS) 170 { 171 int error, val; 172 173 val = V_ip6_maxfragpackets; 174 error = sysctl_handle_int(oidp, &val, 0, req); 175 if (error != 0 || !req->newptr) 176 return (error); 177 V_ip6_maxfragpackets = val; 178 frag6_set_bucketsize(); 179 return (0); 180 } 181 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, 182 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, NULL, 0, 183 sysctl_ip6_maxfragpackets, "I", 184 "Default maximum number of outstanding fragmented IPv6 packets. " 185 "A value of 0 means no fragmented packets will be accepted, while a " 186 "a value of -1 means no limit"); 187 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket, 188 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0, 189 "Maximum allowed number of fragments per packet"); 190 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize, 191 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0, 192 "Maximum number of reassembly queues per hash bucket"); 193 194 195 /* 196 * Remove the IPv6 fragmentation header from the mbuf. 197 */ 198 int 199 ip6_deletefraghdr(struct mbuf *m, int offset, int wait) 200 { 201 struct ip6_hdr *ip6; 202 struct mbuf *t; 203 204 /* Delete frag6 header. */ 205 if (m->m_len >= offset + sizeof(struct ip6_frag)) { 206 207 /* This is the only possible case with !PULLDOWN_TEST. */ 208 ip6 = mtod(m, struct ip6_hdr *); 209 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), 210 offset); 211 m->m_data += sizeof(struct ip6_frag); 212 m->m_len -= sizeof(struct ip6_frag); 213 } else { 214 215 /* This comes with no copy if the boundary is on cluster. */ 216 if ((t = m_split(m, offset, wait)) == NULL) 217 return (ENOMEM); 218 m_adj(t, sizeof(struct ip6_frag)); 219 m_cat(m, t); 220 } 221 222 m->m_flags |= M_FRAGMENTED; 223 return (0); 224 } 225 226 /* 227 * Free a fragment reassembly header and all associated datagrams. 228 */ 229 static void 230 frag6_freef(struct ip6q *q6, uint32_t bucket) 231 { 232 struct ip6_hdr *ip6; 233 struct ip6asfrag *af6, *down6; 234 struct mbuf *m; 235 236 IP6QB_LOCK_ASSERT(bucket); 237 238 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 239 af6 = down6) { 240 241 m = IP6_REASS_MBUF(af6); 242 down6 = af6->ip6af_down; 243 frag6_deq(af6, bucket); 244 245 /* 246 * Return ICMP time exceeded error for the 1st fragment. 247 * Just free other fragments. 248 */ 249 if (af6->ip6af_off == 0) { 250 251 /* Adjust pointer. */ 252 ip6 = mtod(m, struct ip6_hdr *); 253 254 /* Restore source and destination addresses. */ 255 ip6->ip6_src = q6->ip6q_src; 256 ip6->ip6_dst = q6->ip6q_dst; 257 258 icmp6_error(m, ICMP6_TIME_EXCEEDED, 259 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 260 } else 261 m_freem(m); 262 263 free(af6, M_FRAG6); 264 } 265 frag6_remque(q6, bucket); 266 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 267 #ifdef MAC 268 mac_ip6q_destroy(q6); 269 #endif 270 free(q6, M_FRAG6); 271 atomic_subtract_int(&V_frag6_nfragpackets, 1); 272 } 273 274 /* 275 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 276 * each other, in terms of next header field handling in fragment header. 277 * While the sender will use the same value for all of the fragmented packets, 278 * receiver is suggested not to check for consistency. 279 * 280 * Fragment rules (p18,p19): 281 * (2) A Fragment header containing: 282 * The Next Header value that identifies the first header 283 * after the Per-Fragment headers of the original packet. 284 * -> next header field is same for all fragments 285 * 286 * Reassembly rule (p20): 287 * The Next Header field of the last header of the Per-Fragment 288 * headers is obtained from the Next Header field of the first 289 * fragment's Fragment header. 290 * -> should grab it from the first fragment only 291 * 292 * The following note also contradicts with fragment rule - no one is going to 293 * send different fragment with different next header field. 294 * 295 * Additional note (p22) [not an error]: 296 * The Next Header values in the Fragment headers of different 297 * fragments of the same original packet may differ. Only the value 298 * from the Offset zero fragment packet is used for reassembly. 299 * -> should grab it from the first fragment only 300 * 301 * There is no explicit reason given in the RFC. Historical reason maybe? 302 */ 303 /* 304 * Fragment input. 305 */ 306 int 307 frag6_input(struct mbuf **mp, int *offp, int proto) 308 { 309 struct ifnet *dstifp; 310 struct in6_ifaddr *ia6; 311 struct ip6_hdr *ip6; 312 struct ip6_frag *ip6f; 313 struct ip6q *head, *q6; 314 struct ip6asfrag *af6, *af6dwn, *ip6af; 315 struct mbuf *m, *t; 316 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 317 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 318 uint32_t bucket, *hashkeyp; 319 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 320 int nxt, offset, plen; 321 uint8_t ecn, ecn0; 322 bool only_frag; 323 #ifdef RSS 324 struct ip6_direct_ctx *ip6dc; 325 struct m_tag *mtag; 326 #endif 327 328 m = *mp; 329 offset = *offp; 330 331 ip6 = mtod(m, struct ip6_hdr *); 332 #ifndef PULLDOWN_TEST 333 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 334 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 335 #else 336 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 337 if (ip6f == NULL) 338 return (IPPROTO_DONE); 339 #endif 340 341 dstifp = NULL; 342 /* Find the destination interface of the packet. */ 343 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 344 if (ia6 != NULL) { 345 dstifp = ia6->ia_ifp; 346 ifa_free(&ia6->ia_ifa); 347 } 348 349 /* Jumbo payload cannot contain a fragment header. */ 350 if (ip6->ip6_plen == 0) { 351 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 352 in6_ifstat_inc(dstifp, ifs6_reass_fail); 353 return (IPPROTO_DONE); 354 } 355 356 /* 357 * Check whether fragment packet's fragment length is a 358 * multiple of 8 octets (unless it is the last one). 359 * sizeof(struct ip6_frag) == 8 360 * sizeof(struct ip6_hdr) = 40 361 */ 362 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 363 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 364 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 365 offsetof(struct ip6_hdr, ip6_plen)); 366 in6_ifstat_inc(dstifp, ifs6_reass_fail); 367 return (IPPROTO_DONE); 368 } 369 370 IP6STAT_INC(ip6s_fragments); 371 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 372 373 /* Offset now points to data portion. */ 374 offset += sizeof(struct ip6_frag); 375 376 /* 377 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 378 * unrelated to any reassembly. Still need to remove the frag hdr. 379 * See RFC 6946 and section 4.5 of RFC 8200. 380 */ 381 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { 382 IP6STAT_INC(ip6s_atomicfrags); 383 /* XXX-BZ handle correctly. */ 384 in6_ifstat_inc(dstifp, ifs6_reass_ok); 385 *offp = offset; 386 m->m_flags |= M_FRAGMENTED; 387 return (ip6f->ip6f_nxt); 388 } 389 390 /* Get fragment length and discard 0-byte fragments. */ 391 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 392 if (frgpartlen == 0) { 393 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 394 offsetof(struct ip6_hdr, ip6_plen)); 395 in6_ifstat_inc(dstifp, ifs6_reass_fail); 396 IP6STAT_INC(ip6s_fragdropped); 397 return (IPPROTO_DONE); 398 } 399 400 /* Generate a hash value for fragment bucket selection. */ 401 hashkeyp = hashkey; 402 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 403 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 404 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 405 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 406 *hashkeyp = ip6f->ip6f_ident; 407 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 408 bucket &= IP6REASS_HMASK; 409 head = IP6QB_HEAD(bucket); 410 IP6QB_LOCK(bucket); 411 412 /* 413 * Enforce upper bound on number of fragments for the entire system. 414 * If maxfrag is 0, never accept fragments. 415 * If maxfrag is -1, accept all fragments without limitation. 416 */ 417 if (ip6_maxfrags < 0) 418 ; 419 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 420 goto dropfrag; 421 422 for (q6 = head->ip6q_next; q6 != head; q6 = q6->ip6q_next) 423 if (ip6f->ip6f_ident == q6->ip6q_ident && 424 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 425 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 426 #ifdef MAC 427 && mac_ip6q_match(m, q6) 428 #endif 429 ) 430 break; 431 432 only_frag = false; 433 if (q6 == head) { 434 435 /* A first fragment to arrive creates a reassembly queue. */ 436 only_frag = true; 437 438 /* 439 * Enforce upper bound on number of fragmented packets 440 * for which we attempt reassembly; 441 * If maxfragpackets is 0, never accept fragments. 442 * If maxfragpackets is -1, accept all fragments without 443 * limitation. 444 */ 445 if (V_ip6_maxfragpackets < 0) 446 ; 447 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 448 atomic_load_int(&V_frag6_nfragpackets) >= 449 (u_int)V_ip6_maxfragpackets) 450 goto dropfrag; 451 atomic_add_int(&V_frag6_nfragpackets, 1); 452 453 /* Allocate IPv6 fragement packet queue entry. */ 454 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 455 M_NOWAIT | M_ZERO); 456 if (q6 == NULL) 457 goto dropfrag; 458 #ifdef MAC 459 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 460 free(q6, M_FRAG6); 461 goto dropfrag; 462 } 463 mac_ip6q_create(m, q6); 464 #endif 465 frag6_insque_head(q6, head, bucket); 466 467 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 468 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; 469 #ifdef notyet 470 q6->ip6q_nxtp = (u_char *)nxtp; 471 #endif 472 q6->ip6q_ident = ip6f->ip6f_ident; 473 q6->ip6q_ttl = IPV6_FRAGTTL; 474 q6->ip6q_src = ip6->ip6_src; 475 q6->ip6q_dst = ip6->ip6_dst; 476 q6->ip6q_ecn = 477 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 478 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 479 480 q6->ip6q_nfrag = 0; 481 } 482 483 /* 484 * If it is the 1st fragment, record the length of the 485 * unfragmentable part and the next header of the fragment header. 486 */ 487 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 488 if (fragoff == 0) { 489 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 490 sizeof(struct ip6_frag); 491 q6->ip6q_nxt = ip6f->ip6f_nxt; 492 } 493 494 /* 495 * Check that the reassembled packet would not exceed 65535 bytes 496 * in size. 497 * If it would exceed, discard the fragment and return an ICMP error. 498 */ 499 if (q6->ip6q_unfrglen >= 0) { 500 /* The 1st fragment has already arrived. */ 501 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 502 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 503 offset - sizeof(struct ip6_frag) + 504 offsetof(struct ip6_frag, ip6f_offlg)); 505 IP6QB_UNLOCK(bucket); 506 return (IPPROTO_DONE); 507 } 508 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 509 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 510 offset - sizeof(struct ip6_frag) + 511 offsetof(struct ip6_frag, ip6f_offlg)); 512 IP6QB_UNLOCK(bucket); 513 return (IPPROTO_DONE); 514 } 515 /* 516 * If it is the first fragment, do the above check for each 517 * fragment already stored in the reassembly queue. 518 */ 519 if (fragoff == 0) { 520 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 521 af6 = af6dwn) { 522 af6dwn = af6->ip6af_down; 523 524 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > 525 IPV6_MAXPACKET) { 526 struct ip6_hdr *ip6err; 527 struct mbuf *merr; 528 int erroff; 529 530 merr = IP6_REASS_MBUF(af6); 531 erroff = af6->ip6af_offset; 532 533 /* Dequeue the fragment. */ 534 frag6_deq(af6, bucket); 535 free(af6, M_FRAG6); 536 537 /* Adjust pointer. */ 538 ip6err = mtod(merr, struct ip6_hdr *); 539 540 /* 541 * Restore source and destination addresses 542 * in the erroneous IPv6 header. 543 */ 544 ip6err->ip6_src = q6->ip6q_src; 545 ip6err->ip6_dst = q6->ip6q_dst; 546 547 icmp6_error(merr, ICMP6_PARAM_PROB, 548 ICMP6_PARAMPROB_HEADER, 549 erroff - sizeof(struct ip6_frag) + 550 offsetof(struct ip6_frag, ip6f_offlg)); 551 } 552 } 553 } 554 555 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 556 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 557 M_NOWAIT | M_ZERO); 558 if (ip6af == NULL) 559 goto dropfrag; 560 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; 561 ip6af->ip6af_off = fragoff; 562 ip6af->ip6af_frglen = frgpartlen; 563 ip6af->ip6af_offset = offset; 564 IP6_REASS_MBUF(ip6af) = m; 565 566 if (only_frag) { 567 af6 = (struct ip6asfrag *)q6; 568 goto insert; 569 } 570 571 /* Do duplicate, condition, and boundry checks. */ 572 /* 573 * Handle ECN by comparing this segment with the first one; 574 * if CE is set, do not lose CE. 575 * Drop if CE and not-ECT are mixed for the same packet. 576 */ 577 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 578 ecn0 = q6->ip6q_ecn; 579 if (ecn == IPTOS_ECN_CE) { 580 if (ecn0 == IPTOS_ECN_NOTECT) { 581 free(ip6af, M_FRAG6); 582 goto dropfrag; 583 } 584 if (ecn0 != IPTOS_ECN_CE) 585 q6->ip6q_ecn = IPTOS_ECN_CE; 586 } 587 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 588 free(ip6af, M_FRAG6); 589 goto dropfrag; 590 } 591 592 /* Find a fragmented part which begins after this one does. */ 593 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 594 af6 = af6->ip6af_down) 595 if (af6->ip6af_off > ip6af->ip6af_off) 596 break; 597 598 /* 599 * If the incoming framgent overlaps some existing fragments in 600 * the reassembly queue, drop both the new fragment and the 601 * entire reassembly queue. However, if the new fragment 602 * is an exact duplicate of an existing fragment, only silently 603 * drop the existing fragment and leave the fragmentation queue 604 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 605 */ 606 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 607 if (af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen - 608 ip6af->ip6af_off > 0) { 609 free(ip6af, M_FRAG6); 610 goto dropfrag; 611 } 612 } 613 if (af6 != (struct ip6asfrag *)q6) { 614 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 615 af6->ip6af_off > 0) { 616 free(ip6af, M_FRAG6); 617 goto dropfrag; 618 } 619 } 620 621 insert: 622 #ifdef MAC 623 if (!only_frag) 624 mac_ip6q_update(m, q6); 625 #endif 626 627 /* 628 * Stick new segment in its place; check for complete reassembly. 629 * If not complete, check fragment limit. Move to front of packet 630 * queue, as we are the most recently active fragmented packet. 631 */ 632 frag6_enq(ip6af, af6->ip6af_up, bucket); 633 atomic_add_int(&frag6_nfrags, 1); 634 q6->ip6q_nfrag++; 635 plen = 0; 636 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 637 af6 = af6->ip6af_down) { 638 if (af6->ip6af_off != plen) { 639 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 640 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 641 frag6_freef(q6, bucket); 642 } 643 IP6QB_UNLOCK(bucket); 644 return (IPPROTO_DONE); 645 } 646 plen += af6->ip6af_frglen; 647 } 648 if (af6->ip6af_up->ip6af_mff) { 649 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 650 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 651 frag6_freef(q6, bucket); 652 } 653 IP6QB_UNLOCK(bucket); 654 return (IPPROTO_DONE); 655 } 656 657 /* Reassembly is complete; concatenate fragments. */ 658 ip6af = q6->ip6q_down; 659 t = m = IP6_REASS_MBUF(ip6af); 660 af6 = ip6af->ip6af_down; 661 frag6_deq(ip6af, bucket); 662 while (af6 != (struct ip6asfrag *)q6) { 663 m->m_pkthdr.csum_flags &= 664 IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags; 665 m->m_pkthdr.csum_data += 666 IP6_REASS_MBUF(af6)->m_pkthdr.csum_data; 667 668 af6dwn = af6->ip6af_down; 669 frag6_deq(af6, bucket); 670 while (t->m_next) 671 t = t->m_next; 672 m_adj(IP6_REASS_MBUF(af6), af6->ip6af_offset); 673 m_demote_pkthdr(IP6_REASS_MBUF(af6)); 674 m_cat(t, IP6_REASS_MBUF(af6)); 675 free(af6, M_FRAG6); 676 af6 = af6dwn; 677 } 678 679 while (m->m_pkthdr.csum_data & 0xffff0000) 680 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 681 (m->m_pkthdr.csum_data >> 16); 682 683 /* Adjust offset to point where the original next header starts. */ 684 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 685 free(ip6af, M_FRAG6); 686 ip6 = mtod(m, struct ip6_hdr *); 687 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 688 if (q6->ip6q_ecn == IPTOS_ECN_CE) 689 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 690 nxt = q6->ip6q_nxt; 691 692 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { 693 frag6_remque(q6, bucket); 694 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 695 #ifdef MAC 696 mac_ip6q_destroy(q6); 697 #endif 698 free(q6, M_FRAG6); 699 atomic_subtract_int(&V_frag6_nfragpackets, 1); 700 701 goto dropfrag; 702 } 703 704 /* Set nxt(-hdr field value) to the original value. */ 705 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 706 (caddr_t)&nxt); 707 708 frag6_remque(q6, bucket); 709 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 710 #ifdef MAC 711 mac_ip6q_reassemble(q6, m); 712 mac_ip6q_destroy(q6); 713 #endif 714 free(q6, M_FRAG6); 715 atomic_subtract_int(&V_frag6_nfragpackets, 1); 716 717 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 718 719 plen = 0; 720 for (t = m; t; t = t->m_next) 721 plen += t->m_len; 722 m->m_pkthdr.len = plen; 723 } 724 725 #ifdef RSS 726 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 727 M_NOWAIT); 728 if (mtag == NULL) 729 goto dropfrag; 730 731 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 732 ip6dc->ip6dc_nxt = nxt; 733 ip6dc->ip6dc_off = offset; 734 735 m_tag_prepend(m, mtag); 736 #endif 737 738 IP6QB_UNLOCK(bucket); 739 IP6STAT_INC(ip6s_reassembled); 740 in6_ifstat_inc(dstifp, ifs6_reass_ok); 741 742 #ifdef RSS 743 /* Queue/dispatch for reprocessing. */ 744 netisr_dispatch(NETISR_IPV6_DIRECT, m); 745 return (IPPROTO_DONE); 746 #endif 747 748 /* Tell launch routine the next header. */ 749 *mp = m; 750 *offp = offset; 751 752 return (nxt); 753 754 dropfrag: 755 IP6QB_UNLOCK(bucket); 756 in6_ifstat_inc(dstifp, ifs6_reass_fail); 757 IP6STAT_INC(ip6s_fragdropped); 758 m_freem(m); 759 return (IPPROTO_DONE); 760 } 761 762 /* 763 * IPv6 reassembling timer processing; 764 * if a timer expires on a reassembly queue, discard it. 765 */ 766 void 767 frag6_slowtimo(void) 768 { 769 VNET_ITERATOR_DECL(vnet_iter); 770 struct ip6q *head, *q6; 771 uint32_t bucket; 772 773 VNET_LIST_RLOCK_NOSLEEP(); 774 VNET_FOREACH(vnet_iter) { 775 CURVNET_SET(vnet_iter); 776 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 777 IP6QB_LOCK(bucket); 778 head = IP6QB_HEAD(bucket); 779 q6 = head->ip6q_next; 780 if (q6 == NULL) { 781 /* 782 * XXXJTL: This should never happen. This 783 * should turn into an assertion. 784 */ 785 IP6QB_UNLOCK(bucket); 786 continue; 787 } 788 while (q6 != head) { 789 --q6->ip6q_ttl; 790 q6 = q6->ip6q_next; 791 if (q6->ip6q_prev->ip6q_ttl == 0) { 792 IP6STAT_ADD(ip6s_fragtimeout, 793 q6->ip6q_prev->ip6q_nfrag); 794 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 795 frag6_freef(q6->ip6q_prev, bucket); 796 } 797 } 798 /* 799 * If we are over the maximum number of fragments 800 * (due to the limit being lowered), drain off 801 * enough to get down to the new limit. 802 * Note that we drain all reassembly queues if 803 * maxfragpackets is 0 (fragmentation is disabled), 804 * and do not enforce a limit when maxfragpackets 805 * is negative. 806 */ 807 while ((V_ip6_maxfragpackets == 0 || 808 (V_ip6_maxfragpackets > 0 && 809 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 810 head->ip6q_prev != head) { 811 IP6STAT_ADD(ip6s_fragoverflow, 812 q6->ip6q_prev->ip6q_nfrag); 813 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 814 frag6_freef(head->ip6q_prev, bucket); 815 } 816 IP6QB_UNLOCK(bucket); 817 } 818 /* 819 * If we are still over the maximum number of fragmented 820 * packets, drain off enough to get down to the new limit. 821 */ 822 bucket = 0; 823 while (V_ip6_maxfragpackets >= 0 && 824 atomic_load_int(&V_frag6_nfragpackets) > 825 (u_int)V_ip6_maxfragpackets) { 826 IP6QB_LOCK(bucket); 827 head = IP6QB_HEAD(bucket); 828 if (head->ip6q_prev != head) { 829 IP6STAT_ADD(ip6s_fragoverflow, 830 q6->ip6q_prev->ip6q_nfrag); 831 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 832 frag6_freef(head->ip6q_prev, bucket); 833 } 834 IP6QB_UNLOCK(bucket); 835 bucket = (bucket + 1) % IP6REASS_NHASH; 836 } 837 CURVNET_RESTORE(); 838 } 839 VNET_LIST_RUNLOCK_NOSLEEP(); 840 } 841 842 /* 843 * Eventhandler to adjust limits in case nmbclusters change. 844 */ 845 static void 846 frag6_change(void *tag) 847 { 848 VNET_ITERATOR_DECL(vnet_iter); 849 850 ip6_maxfrags = IP6_MAXFRAGS; 851 VNET_LIST_RLOCK_NOSLEEP(); 852 VNET_FOREACH(vnet_iter) { 853 CURVNET_SET(vnet_iter); 854 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 855 frag6_set_bucketsize(); 856 CURVNET_RESTORE(); 857 } 858 VNET_LIST_RUNLOCK_NOSLEEP(); 859 } 860 861 /* 862 * Initialise reassembly queue and fragment identifier. 863 */ 864 void 865 frag6_init(void) 866 { 867 struct ip6q *q6; 868 uint32_t bucket; 869 870 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 871 frag6_set_bucketsize(); 872 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 873 q6 = IP6QB_HEAD(bucket); 874 q6->ip6q_next = q6->ip6q_prev = q6; 875 mtx_init(&V_ip6qb[bucket].lock, "ip6qlock", NULL, MTX_DEF); 876 V_ip6qb[bucket].count = 0; 877 } 878 V_ip6qb_hashseed = arc4random(); 879 V_ip6_maxfragsperpacket = 64; 880 if (!IS_DEFAULT_VNET(curvnet)) 881 return; 882 883 ip6_maxfrags = IP6_MAXFRAGS; 884 EVENTHANDLER_REGISTER(nmbclusters_change, 885 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 886 } 887 888 /* 889 * Drain off all datagram fragments. 890 */ 891 void 892 frag6_drain(void) 893 { 894 VNET_ITERATOR_DECL(vnet_iter); 895 struct ip6q *head; 896 uint32_t bucket; 897 898 VNET_LIST_RLOCK_NOSLEEP(); 899 VNET_FOREACH(vnet_iter) { 900 CURVNET_SET(vnet_iter); 901 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 902 if (IP6QB_TRYLOCK(bucket) == 0) 903 continue; 904 head = IP6QB_HEAD(bucket); 905 while (head->ip6q_next != head) { 906 IP6STAT_INC(ip6s_fragdropped); 907 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 908 frag6_freef(head->ip6q_next, bucket); 909 } 910 IP6QB_UNLOCK(bucket); 911 } 912 CURVNET_RESTORE(); 913 } 914 VNET_LIST_RUNLOCK_NOSLEEP(); 915 } 916 917 /* 918 * Put an ip fragment on a reassembly chain. 919 * Like insque, but pointers in middle of structure. 920 */ 921 static void 922 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6, 923 uint32_t bucket __unused) 924 { 925 926 IP6QB_LOCK_ASSERT(bucket); 927 928 af6->ip6af_up = up6; 929 af6->ip6af_down = up6->ip6af_down; 930 up6->ip6af_down->ip6af_up = af6; 931 up6->ip6af_down = af6; 932 } 933 934 /* 935 * To frag6_enq as remque is to insque. 936 */ 937 static void 938 frag6_deq(struct ip6asfrag *af6, uint32_t bucket __unused) 939 { 940 941 IP6QB_LOCK_ASSERT(bucket); 942 943 af6->ip6af_up->ip6af_down = af6->ip6af_down; 944 af6->ip6af_down->ip6af_up = af6->ip6af_up; 945 } 946 947 static void 948 frag6_insque_head(struct ip6q *new, struct ip6q *old, uint32_t bucket) 949 { 950 951 IP6QB_LOCK_ASSERT(bucket); 952 KASSERT(IP6QB_HEAD(bucket) == old, 953 ("%s: attempt to insert at head of wrong bucket" 954 " (bucket=%u, old=%p)", __func__, bucket, old)); 955 956 new->ip6q_prev = old; 957 new->ip6q_next = old->ip6q_next; 958 old->ip6q_next->ip6q_prev= new; 959 old->ip6q_next = new; 960 V_ip6qb[bucket].count++; 961 } 962 963 static void 964 frag6_remque(struct ip6q *p6, uint32_t bucket) 965 { 966 967 IP6QB_LOCK_ASSERT(bucket); 968 969 p6->ip6q_prev->ip6q_next = p6->ip6q_next; 970 p6->ip6q_next->ip6q_prev = p6->ip6q_prev; 971 V_ip6qb[bucket].count--; 972 } 973