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 #ifdef VIMAGE 104 /* A flag to indicate if IPv6 fragmentation is initialized. */ 105 VNET_DEFINE_STATIC(bool, frag6_on); 106 #define V_frag6_on VNET(frag6_on) 107 #endif 108 109 /* System wide (global) maximum and count of packets in reassembly queues. */ 110 static int ip6_maxfrags; 111 static volatile u_int frag6_nfrags = 0; 112 113 /* Maximum and current packets in per-VNET reassembly queue. */ 114 VNET_DEFINE_STATIC(int, ip6_maxfragpackets); 115 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets); 116 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) 117 #define V_frag6_nfragpackets VNET(frag6_nfragpackets) 118 119 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */ 120 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize); 121 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket); 122 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize) 123 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket) 124 125 /* Per-VNET reassembly queue buckets. */ 126 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]); 127 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed); 128 #define V_ip6qb VNET(ip6qb) 129 #define V_ip6qb_hashseed VNET(ip6qb_hashseed) 130 131 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock) 132 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock) 133 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED) 134 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock) 135 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].ip6q) 136 137 /* 138 * By default, limit the number of IP6 fragments across all reassembly 139 * queues to 1/32 of the total number of mbuf clusters. 140 * 141 * Limit the total number of reassembly queues per VNET to the 142 * IP6 fragment limit, but ensure the limit will not allow any bucket 143 * to grow above 100 items. (The bucket limit is 144 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct 145 * multiplier to reach a 100-item limit.) 146 * The 100-item limit was chosen as brief testing seems to show that 147 * this produces "reasonable" performance on some subset of systems 148 * under DoS attack. 149 */ 150 #define IP6_MAXFRAGS (nmbclusters / 32) 151 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) 152 153 154 /* 155 * Sysctls and helper function. 156 */ 157 SYSCTL_DECL(_net_inet6_ip6); 158 159 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags, 160 CTLFLAG_RD, __DEVOLATILE(u_int *, &frag6_nfrags), 0, 161 "Global number of IPv6 fragments across all reassembly queues."); 162 163 static void 164 frag6_set_bucketsize(void) 165 { 166 int i; 167 168 if ((i = V_ip6_maxfragpackets) > 0) 169 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); 170 } 171 172 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, 173 CTLFLAG_RW, &ip6_maxfrags, 0, 174 "Maximum allowed number of outstanding IPv6 packet fragments. " 175 "A value of 0 means no fragmented packets will be accepted, while a " 176 "a value of -1 means no limit"); 177 178 static int 179 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS) 180 { 181 int error, val; 182 183 val = V_ip6_maxfragpackets; 184 error = sysctl_handle_int(oidp, &val, 0, req); 185 if (error != 0 || !req->newptr) 186 return (error); 187 V_ip6_maxfragpackets = val; 188 frag6_set_bucketsize(); 189 return (0); 190 } 191 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, 192 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, NULL, 0, 193 sysctl_ip6_maxfragpackets, "I", 194 "Default maximum number of outstanding fragmented IPv6 packets. " 195 "A value of 0 means no fragmented packets will be accepted, while a " 196 "a value of -1 means no limit"); 197 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket, 198 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0, 199 "Maximum allowed number of fragments per packet"); 200 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize, 201 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0, 202 "Maximum number of reassembly queues per hash bucket"); 203 204 205 /* 206 * Remove the IPv6 fragmentation header from the mbuf. 207 */ 208 int 209 ip6_deletefraghdr(struct mbuf *m, int offset, int wait) 210 { 211 struct ip6_hdr *ip6; 212 struct mbuf *t; 213 214 /* Delete frag6 header. */ 215 if (m->m_len >= offset + sizeof(struct ip6_frag)) { 216 217 /* This is the only possible case with !PULLDOWN_TEST. */ 218 ip6 = mtod(m, struct ip6_hdr *); 219 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), 220 offset); 221 m->m_data += sizeof(struct ip6_frag); 222 m->m_len -= sizeof(struct ip6_frag); 223 } else { 224 225 /* This comes with no copy if the boundary is on cluster. */ 226 if ((t = m_split(m, offset, wait)) == NULL) 227 return (ENOMEM); 228 m_adj(t, sizeof(struct ip6_frag)); 229 m_cat(m, t); 230 } 231 232 m->m_flags |= M_FRAGMENTED; 233 return (0); 234 } 235 236 /* 237 * Free a fragment reassembly header and all associated datagrams. 238 */ 239 static void 240 frag6_freef(struct ip6q *q6, uint32_t bucket) 241 { 242 struct ip6_hdr *ip6; 243 struct ip6asfrag *af6, *down6; 244 struct mbuf *m; 245 246 IP6QB_LOCK_ASSERT(bucket); 247 248 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 249 af6 = down6) { 250 251 m = IP6_REASS_MBUF(af6); 252 down6 = af6->ip6af_down; 253 frag6_deq(af6, bucket); 254 255 /* 256 * Return ICMP time exceeded error for the 1st fragment. 257 * Just free other fragments. 258 */ 259 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { 260 261 /* Adjust pointer. */ 262 ip6 = mtod(m, struct ip6_hdr *); 263 264 /* Restore source and destination addresses. */ 265 ip6->ip6_src = q6->ip6q_src; 266 ip6->ip6_dst = q6->ip6q_dst; 267 268 icmp6_error(m, ICMP6_TIME_EXCEEDED, 269 ICMP6_TIME_EXCEED_REASSEMBLY, 0); 270 } else 271 m_freem(m); 272 273 free(af6, M_FRAG6); 274 } 275 frag6_remque(q6, bucket); 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 ip6q *q6, *q6n, *head; 292 struct ip6asfrag *af6; 293 struct mbuf *m; 294 int i; 295 296 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 297 298 #ifdef VIMAGE 299 /* 300 * Skip processing if IPv6 reassembly is not initialised or 301 * torn down by frag6_destroy(). 302 */ 303 if (!V_frag6_on) 304 return; 305 #endif 306 307 CURVNET_SET_QUIET(ifp->if_vnet); 308 for (i = 0; i < IP6REASS_NHASH; i++) { 309 IP6QB_LOCK(i); 310 head = IP6QB_HEAD(i); 311 /* Scan fragment list. */ 312 for (q6 = head->ip6q_next; q6 != head; q6 = q6n) { 313 q6n = q6->ip6q_next; 314 315 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 316 af6 = af6->ip6af_down) { 317 m = IP6_REASS_MBUF(af6); 318 319 /* clear no longer valid rcvif pointer */ 320 if (m->m_pkthdr.rcvif == ifp) 321 m->m_pkthdr.rcvif = NULL; 322 } 323 } 324 IP6QB_UNLOCK(i); 325 } 326 CURVNET_RESTORE(); 327 } 328 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); 329 330 /* 331 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with 332 * each other, in terms of next header field handling in fragment header. 333 * While the sender will use the same value for all of the fragmented packets, 334 * receiver is suggested not to check for consistency. 335 * 336 * Fragment rules (p18,p19): 337 * (2) A Fragment header containing: 338 * The Next Header value that identifies the first header 339 * after the Per-Fragment headers of the original packet. 340 * -> next header field is same for all fragments 341 * 342 * Reassembly rule (p20): 343 * The Next Header field of the last header of the Per-Fragment 344 * headers is obtained from the Next Header field of the first 345 * fragment's Fragment header. 346 * -> should grab it from the first fragment only 347 * 348 * The following note also contradicts with fragment rule - no one is going to 349 * send different fragment with different next header field. 350 * 351 * Additional note (p22) [not an error]: 352 * The Next Header values in the Fragment headers of different 353 * fragments of the same original packet may differ. Only the value 354 * from the Offset zero fragment packet is used for reassembly. 355 * -> should grab it from the first fragment only 356 * 357 * There is no explicit reason given in the RFC. Historical reason maybe? 358 */ 359 /* 360 * Fragment input. 361 */ 362 int 363 frag6_input(struct mbuf **mp, int *offp, int proto) 364 { 365 struct ifnet *dstifp; 366 struct ifnet *srcifp; 367 struct in6_ifaddr *ia6; 368 struct ip6_hdr *ip6; 369 struct ip6_frag *ip6f; 370 struct ip6q *head, *q6; 371 struct ip6asfrag *af6, *af6dwn, *ip6af; 372 struct mbuf *m, *t; 373 uint32_t hashkey[(sizeof(struct in6_addr) * 2 + 374 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; 375 uint32_t bucket, *hashkeyp; 376 int fragoff, frgpartlen; /* Must be larger than uint16_t. */ 377 int nxt, offset, plen; 378 uint8_t ecn, ecn0; 379 bool only_frag; 380 #ifdef RSS 381 struct ip6_direct_ctx *ip6dc; 382 struct m_tag *mtag; 383 #endif 384 385 m = *mp; 386 offset = *offp; 387 388 ip6 = mtod(m, struct ip6_hdr *); 389 #ifndef PULLDOWN_TEST 390 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); 391 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 392 #else 393 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); 394 if (ip6f == NULL) 395 return (IPPROTO_DONE); 396 #endif 397 398 /* 399 * Store receive network interface pointer for later. 400 */ 401 srcifp = m->m_pkthdr.rcvif; 402 403 dstifp = NULL; 404 /* Find the destination interface of the packet. */ 405 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 406 if (ia6 != NULL) { 407 dstifp = ia6->ia_ifp; 408 ifa_free(&ia6->ia_ifa); 409 } 410 411 /* Jumbo payload cannot contain a fragment header. */ 412 if (ip6->ip6_plen == 0) { 413 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); 414 in6_ifstat_inc(dstifp, ifs6_reass_fail); 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 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && 425 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { 426 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 427 offsetof(struct ip6_hdr, ip6_plen)); 428 in6_ifstat_inc(dstifp, ifs6_reass_fail); 429 return (IPPROTO_DONE); 430 } 431 432 IP6STAT_INC(ip6s_fragments); 433 in6_ifstat_inc(dstifp, ifs6_reass_reqd); 434 435 /* Offset now points to data portion. */ 436 offset += sizeof(struct ip6_frag); 437 438 /* 439 * Handle "atomic" fragments (offset and m bit set to 0) upfront, 440 * unrelated to any reassembly. Still need to remove the frag hdr. 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 /* XXX-BZ handle correctly. */ 446 in6_ifstat_inc(dstifp, ifs6_reass_ok); 447 *offp = offset; 448 m->m_flags |= M_FRAGMENTED; 449 return (ip6f->ip6f_nxt); 450 } 451 452 /* Get fragment length and discard 0-byte fragments. */ 453 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; 454 if (frgpartlen == 0) { 455 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 456 offsetof(struct ip6_hdr, ip6_plen)); 457 in6_ifstat_inc(dstifp, ifs6_reass_fail); 458 IP6STAT_INC(ip6s_fragdropped); 459 return (IPPROTO_DONE); 460 } 461 462 /* Generate a hash value for fragment bucket selection. */ 463 hashkeyp = hashkey; 464 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); 465 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 466 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); 467 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); 468 *hashkeyp = ip6f->ip6f_ident; 469 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); 470 bucket &= IP6REASS_HMASK; 471 head = IP6QB_HEAD(bucket); 472 IP6QB_LOCK(bucket); 473 474 /* 475 * Enforce upper bound on number of fragments for the entire system. 476 * If maxfrag is 0, never accept fragments. 477 * If maxfrag is -1, accept all fragments without limitation. 478 */ 479 if (ip6_maxfrags < 0) 480 ; 481 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) 482 goto dropfrag; 483 484 for (q6 = head->ip6q_next; q6 != head; q6 = q6->ip6q_next) 485 if (ip6f->ip6f_ident == q6->ip6q_ident && 486 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && 487 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) 488 #ifdef MAC 489 && mac_ip6q_match(m, q6) 490 #endif 491 ) 492 break; 493 494 only_frag = false; 495 if (q6 == head) { 496 497 /* A first fragment to arrive creates a reassembly queue. */ 498 only_frag = true; 499 500 /* 501 * Enforce upper bound on number of fragmented packets 502 * for which we attempt reassembly; 503 * If maxfragpackets is 0, never accept fragments. 504 * If maxfragpackets is -1, accept all fragments without 505 * limitation. 506 */ 507 if (V_ip6_maxfragpackets < 0) 508 ; 509 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || 510 atomic_load_int(&V_frag6_nfragpackets) >= 511 (u_int)V_ip6_maxfragpackets) 512 goto dropfrag; 513 atomic_add_int(&V_frag6_nfragpackets, 1); 514 515 /* Allocate IPv6 fragement packet queue entry. */ 516 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, 517 M_NOWAIT | M_ZERO); 518 if (q6 == NULL) 519 goto dropfrag; 520 #ifdef MAC 521 if (mac_ip6q_init(q6, M_NOWAIT) != 0) { 522 free(q6, M_FRAG6); 523 goto dropfrag; 524 } 525 mac_ip6q_create(m, q6); 526 #endif 527 frag6_insque_head(q6, head, bucket); 528 529 /* ip6q_nxt will be filled afterwards, from 1st fragment. */ 530 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; 531 #ifdef notyet 532 q6->ip6q_nxtp = (u_char *)nxtp; 533 #endif 534 q6->ip6q_ident = ip6f->ip6f_ident; 535 q6->ip6q_ttl = IPV6_FRAGTTL; 536 q6->ip6q_src = ip6->ip6_src; 537 q6->ip6q_dst = ip6->ip6_dst; 538 q6->ip6q_ecn = 539 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 540 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ 541 542 q6->ip6q_nfrag = 0; 543 } 544 545 /* 546 * If it is the 1st fragment, record the length of the 547 * unfragmentable part and the next header of the fragment header. 548 */ 549 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); 550 if (fragoff == 0) { 551 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - 552 sizeof(struct ip6_frag); 553 q6->ip6q_nxt = ip6f->ip6f_nxt; 554 } 555 556 /* 557 * Check that the reassembled packet would not exceed 65535 bytes 558 * in size. 559 * If it would exceed, discard the fragment and return an ICMP error. 560 */ 561 if (q6->ip6q_unfrglen >= 0) { 562 /* The 1st fragment has already arrived. */ 563 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { 564 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 565 offset - sizeof(struct ip6_frag) + 566 offsetof(struct ip6_frag, ip6f_offlg)); 567 IP6QB_UNLOCK(bucket); 568 return (IPPROTO_DONE); 569 } 570 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { 571 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, 572 offset - sizeof(struct ip6_frag) + 573 offsetof(struct ip6_frag, ip6f_offlg)); 574 IP6QB_UNLOCK(bucket); 575 return (IPPROTO_DONE); 576 } 577 /* 578 * If it is the first fragment, do the above check for each 579 * fragment already stored in the reassembly queue. 580 */ 581 if (fragoff == 0) { 582 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 583 af6 = af6dwn) { 584 af6dwn = af6->ip6af_down; 585 586 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > 587 IPV6_MAXPACKET) { 588 struct ip6_hdr *ip6err; 589 struct mbuf *merr; 590 int erroff; 591 592 merr = IP6_REASS_MBUF(af6); 593 erroff = af6->ip6af_offset; 594 595 /* Dequeue the fragment. */ 596 frag6_deq(af6, bucket); 597 free(af6, M_FRAG6); 598 599 /* Set a valid receive interface pointer. */ 600 merr->m_pkthdr.rcvif = srcifp; 601 602 /* Adjust pointer. */ 603 ip6err = mtod(merr, struct ip6_hdr *); 604 605 /* 606 * Restore source and destination addresses 607 * in the erroneous IPv6 header. 608 */ 609 ip6err->ip6_src = q6->ip6q_src; 610 ip6err->ip6_dst = q6->ip6q_dst; 611 612 icmp6_error(merr, ICMP6_PARAM_PROB, 613 ICMP6_PARAMPROB_HEADER, 614 erroff - sizeof(struct ip6_frag) + 615 offsetof(struct ip6_frag, ip6f_offlg)); 616 } 617 } 618 } 619 620 /* Allocate an IPv6 fragement queue entry for this fragmented part. */ 621 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, 622 M_NOWAIT | M_ZERO); 623 if (ip6af == NULL) 624 goto dropfrag; 625 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; 626 ip6af->ip6af_off = fragoff; 627 ip6af->ip6af_frglen = frgpartlen; 628 ip6af->ip6af_offset = offset; 629 IP6_REASS_MBUF(ip6af) = m; 630 631 if (only_frag) { 632 af6 = (struct ip6asfrag *)q6; 633 goto insert; 634 } 635 636 /* Do duplicate, condition, and boundry checks. */ 637 /* 638 * Handle ECN by comparing this segment with the first one; 639 * if CE is set, do not lose CE. 640 * Drop if CE and not-ECT are mixed for the same packet. 641 */ 642 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; 643 ecn0 = q6->ip6q_ecn; 644 if (ecn == IPTOS_ECN_CE) { 645 if (ecn0 == IPTOS_ECN_NOTECT) { 646 free(ip6af, M_FRAG6); 647 goto dropfrag; 648 } 649 if (ecn0 != IPTOS_ECN_CE) 650 q6->ip6q_ecn = IPTOS_ECN_CE; 651 } 652 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { 653 free(ip6af, M_FRAG6); 654 goto dropfrag; 655 } 656 657 /* Find a fragmented part which begins after this one does. */ 658 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 659 af6 = af6->ip6af_down) 660 if (af6->ip6af_off > ip6af->ip6af_off) 661 break; 662 663 /* 664 * If the incoming framgent overlaps some existing fragments in 665 * the reassembly queue, drop both the new fragment and the 666 * entire reassembly queue. However, if the new fragment 667 * is an exact duplicate of an existing fragment, only silently 668 * drop the existing fragment and leave the fragmentation queue 669 * unchanged, as allowed by the RFC. (RFC 8200, 4.5) 670 */ 671 if (af6->ip6af_up != (struct ip6asfrag *)q6) { 672 if (af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen - 673 ip6af->ip6af_off > 0) { 674 free(ip6af, M_FRAG6); 675 goto dropfrag; 676 } 677 } 678 if (af6 != (struct ip6asfrag *)q6) { 679 if (ip6af->ip6af_off + ip6af->ip6af_frglen - 680 af6->ip6af_off > 0) { 681 free(ip6af, M_FRAG6); 682 goto dropfrag; 683 } 684 } 685 686 insert: 687 #ifdef MAC 688 if (!only_frag) 689 mac_ip6q_update(m, q6); 690 #endif 691 692 /* 693 * Stick new segment in its place; check for complete reassembly. 694 * If not complete, check fragment limit. Move to front of packet 695 * queue, as we are the most recently active fragmented packet. 696 */ 697 frag6_enq(ip6af, af6->ip6af_up, bucket); 698 atomic_add_int(&frag6_nfrags, 1); 699 q6->ip6q_nfrag++; 700 plen = 0; 701 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; 702 af6 = af6->ip6af_down) { 703 if (af6->ip6af_off != plen) { 704 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 705 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 706 frag6_freef(q6, bucket); 707 } 708 IP6QB_UNLOCK(bucket); 709 return (IPPROTO_DONE); 710 } 711 plen += af6->ip6af_frglen; 712 } 713 if (af6->ip6af_up->ip6af_mff) { 714 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { 715 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); 716 frag6_freef(q6, bucket); 717 } 718 IP6QB_UNLOCK(bucket); 719 return (IPPROTO_DONE); 720 } 721 722 /* Reassembly is complete; concatenate fragments. */ 723 ip6af = q6->ip6q_down; 724 t = m = IP6_REASS_MBUF(ip6af); 725 af6 = ip6af->ip6af_down; 726 frag6_deq(ip6af, bucket); 727 while (af6 != (struct ip6asfrag *)q6) { 728 m->m_pkthdr.csum_flags &= 729 IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags; 730 m->m_pkthdr.csum_data += 731 IP6_REASS_MBUF(af6)->m_pkthdr.csum_data; 732 733 af6dwn = af6->ip6af_down; 734 frag6_deq(af6, bucket); 735 while (t->m_next) 736 t = t->m_next; 737 m_adj(IP6_REASS_MBUF(af6), af6->ip6af_offset); 738 m_demote_pkthdr(IP6_REASS_MBUF(af6)); 739 m_cat(t, IP6_REASS_MBUF(af6)); 740 free(af6, M_FRAG6); 741 af6 = af6dwn; 742 } 743 744 while (m->m_pkthdr.csum_data & 0xffff0000) 745 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 746 (m->m_pkthdr.csum_data >> 16); 747 748 /* Adjust offset to point where the original next header starts. */ 749 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); 750 free(ip6af, M_FRAG6); 751 ip6 = mtod(m, struct ip6_hdr *); 752 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); 753 if (q6->ip6q_ecn == IPTOS_ECN_CE) 754 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); 755 nxt = q6->ip6q_nxt; 756 757 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { 758 frag6_remque(q6, bucket); 759 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 760 #ifdef MAC 761 mac_ip6q_destroy(q6); 762 #endif 763 free(q6, M_FRAG6); 764 atomic_subtract_int(&V_frag6_nfragpackets, 1); 765 766 goto dropfrag; 767 } 768 769 /* Set nxt(-hdr field value) to the original value. */ 770 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), 771 (caddr_t)&nxt); 772 773 frag6_remque(q6, bucket); 774 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); 775 #ifdef MAC 776 mac_ip6q_reassemble(q6, m); 777 mac_ip6q_destroy(q6); 778 #endif 779 free(q6, M_FRAG6); 780 atomic_subtract_int(&V_frag6_nfragpackets, 1); 781 782 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ 783 784 plen = 0; 785 for (t = m; t; t = t->m_next) 786 plen += t->m_len; 787 m->m_pkthdr.len = plen; 788 /* Set a valid receive interface pointer. */ 789 m->m_pkthdr.rcvif = srcifp; 790 } 791 792 #ifdef RSS 793 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), 794 M_NOWAIT); 795 if (mtag == NULL) 796 goto dropfrag; 797 798 ip6dc = (struct ip6_direct_ctx *)(mtag + 1); 799 ip6dc->ip6dc_nxt = nxt; 800 ip6dc->ip6dc_off = offset; 801 802 m_tag_prepend(m, mtag); 803 #endif 804 805 IP6QB_UNLOCK(bucket); 806 IP6STAT_INC(ip6s_reassembled); 807 in6_ifstat_inc(dstifp, ifs6_reass_ok); 808 809 #ifdef RSS 810 /* Queue/dispatch for reprocessing. */ 811 netisr_dispatch(NETISR_IPV6_DIRECT, m); 812 return (IPPROTO_DONE); 813 #endif 814 815 /* Tell launch routine the next header. */ 816 *mp = m; 817 *offp = offset; 818 819 return (nxt); 820 821 dropfrag: 822 IP6QB_UNLOCK(bucket); 823 in6_ifstat_inc(dstifp, ifs6_reass_fail); 824 IP6STAT_INC(ip6s_fragdropped); 825 m_freem(m); 826 return (IPPROTO_DONE); 827 } 828 829 /* 830 * IPv6 reassembling timer processing; 831 * if a timer expires on a reassembly queue, discard it. 832 */ 833 void 834 frag6_slowtimo(void) 835 { 836 VNET_ITERATOR_DECL(vnet_iter); 837 struct ip6q *head, *q6; 838 uint32_t bucket; 839 840 VNET_LIST_RLOCK_NOSLEEP(); 841 VNET_FOREACH(vnet_iter) { 842 CURVNET_SET(vnet_iter); 843 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 844 IP6QB_LOCK(bucket); 845 head = IP6QB_HEAD(bucket); 846 q6 = head->ip6q_next; 847 if (q6 == NULL) { 848 /* 849 * XXXJTL: This should never happen. This 850 * should turn into an assertion. 851 */ 852 IP6QB_UNLOCK(bucket); 853 continue; 854 } 855 while (q6 != head) { 856 --q6->ip6q_ttl; 857 q6 = q6->ip6q_next; 858 if (q6->ip6q_prev->ip6q_ttl == 0) { 859 IP6STAT_ADD(ip6s_fragtimeout, 860 q6->ip6q_prev->ip6q_nfrag); 861 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 862 frag6_freef(q6->ip6q_prev, bucket); 863 } 864 } 865 /* 866 * If we are over the maximum number of fragments 867 * (due to the limit being lowered), drain off 868 * enough to get down to the new limit. 869 * Note that we drain all reassembly queues if 870 * maxfragpackets is 0 (fragmentation is disabled), 871 * and do not enforce a limit when maxfragpackets 872 * is negative. 873 */ 874 while ((V_ip6_maxfragpackets == 0 || 875 (V_ip6_maxfragpackets > 0 && 876 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && 877 head->ip6q_prev != head) { 878 IP6STAT_ADD(ip6s_fragoverflow, 879 q6->ip6q_prev->ip6q_nfrag); 880 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 881 frag6_freef(head->ip6q_prev, bucket); 882 } 883 IP6QB_UNLOCK(bucket); 884 } 885 /* 886 * If we are still over the maximum number of fragmented 887 * packets, drain off enough to get down to the new limit. 888 */ 889 bucket = 0; 890 while (V_ip6_maxfragpackets >= 0 && 891 atomic_load_int(&V_frag6_nfragpackets) > 892 (u_int)V_ip6_maxfragpackets) { 893 IP6QB_LOCK(bucket); 894 head = IP6QB_HEAD(bucket); 895 if (head->ip6q_prev != head) { 896 IP6STAT_ADD(ip6s_fragoverflow, 897 q6->ip6q_prev->ip6q_nfrag); 898 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 899 frag6_freef(head->ip6q_prev, bucket); 900 } 901 IP6QB_UNLOCK(bucket); 902 bucket = (bucket + 1) % IP6REASS_NHASH; 903 } 904 CURVNET_RESTORE(); 905 } 906 VNET_LIST_RUNLOCK_NOSLEEP(); 907 } 908 909 /* 910 * Eventhandler to adjust limits in case nmbclusters change. 911 */ 912 static void 913 frag6_change(void *tag) 914 { 915 VNET_ITERATOR_DECL(vnet_iter); 916 917 ip6_maxfrags = IP6_MAXFRAGS; 918 VNET_LIST_RLOCK_NOSLEEP(); 919 VNET_FOREACH(vnet_iter) { 920 CURVNET_SET(vnet_iter); 921 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 922 frag6_set_bucketsize(); 923 CURVNET_RESTORE(); 924 } 925 VNET_LIST_RUNLOCK_NOSLEEP(); 926 } 927 928 /* 929 * Initialise reassembly queue and fragment identifier. 930 */ 931 void 932 frag6_init(void) 933 { 934 struct ip6q *q6; 935 uint32_t bucket; 936 937 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; 938 frag6_set_bucketsize(); 939 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 940 q6 = IP6QB_HEAD(bucket); 941 q6->ip6q_next = q6->ip6q_prev = q6; 942 mtx_init(&V_ip6qb[bucket].lock, "ip6qlock", NULL, MTX_DEF); 943 V_ip6qb[bucket].count = 0; 944 } 945 V_ip6qb_hashseed = arc4random(); 946 V_ip6_maxfragsperpacket = 64; 947 #ifdef VIMAGE 948 V_frag6_on = true; 949 #endif 950 if (!IS_DEFAULT_VNET(curvnet)) 951 return; 952 953 ip6_maxfrags = IP6_MAXFRAGS; 954 EVENTHANDLER_REGISTER(nmbclusters_change, 955 frag6_change, NULL, EVENTHANDLER_PRI_ANY); 956 } 957 958 /* 959 * Drain off all datagram fragments. 960 */ 961 static void 962 frag6_drain_one(void) 963 { 964 struct ip6q *head; 965 uint32_t bucket; 966 967 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 968 IP6QB_LOCK(bucket); 969 head = IP6QB_HEAD(bucket); 970 while (head->ip6q_next != head) { 971 IP6STAT_INC(ip6s_fragdropped); 972 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ 973 frag6_freef(head->ip6q_next, bucket); 974 } 975 IP6QB_UNLOCK(bucket); 976 } 977 } 978 979 void 980 frag6_drain(void) 981 { 982 VNET_ITERATOR_DECL(vnet_iter); 983 984 VNET_LIST_RLOCK_NOSLEEP(); 985 VNET_FOREACH(vnet_iter) { 986 CURVNET_SET(vnet_iter); 987 frag6_drain_one(); 988 CURVNET_RESTORE(); 989 } 990 VNET_LIST_RUNLOCK_NOSLEEP(); 991 } 992 993 #ifdef VIMAGE 994 /* 995 * Clear up IPv6 reassembly structures. 996 */ 997 void 998 frag6_destroy(void) 999 { 1000 uint32_t bucket; 1001 1002 frag6_drain_one(); 1003 V_frag6_on = false; 1004 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { 1005 KASSERT(V_ip6qb[bucket].count == 0, 1006 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, 1007 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); 1008 mtx_destroy(&V_ip6qb[bucket].lock); 1009 } 1010 } 1011 #endif 1012 1013 /* 1014 * Put an ip fragment on a reassembly chain. 1015 * Like insque, but pointers in middle of structure. 1016 */ 1017 static void 1018 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6, 1019 uint32_t bucket __unused) 1020 { 1021 1022 IP6QB_LOCK_ASSERT(bucket); 1023 1024 af6->ip6af_up = up6; 1025 af6->ip6af_down = up6->ip6af_down; 1026 up6->ip6af_down->ip6af_up = af6; 1027 up6->ip6af_down = af6; 1028 } 1029 1030 /* 1031 * To frag6_enq as remque is to insque. 1032 */ 1033 static void 1034 frag6_deq(struct ip6asfrag *af6, uint32_t bucket __unused) 1035 { 1036 1037 IP6QB_LOCK_ASSERT(bucket); 1038 1039 af6->ip6af_up->ip6af_down = af6->ip6af_down; 1040 af6->ip6af_down->ip6af_up = af6->ip6af_up; 1041 } 1042 1043 static void 1044 frag6_insque_head(struct ip6q *new, struct ip6q *old, uint32_t bucket) 1045 { 1046 1047 IP6QB_LOCK_ASSERT(bucket); 1048 KASSERT(IP6QB_HEAD(bucket) == old, 1049 ("%s: attempt to insert at head of wrong bucket" 1050 " (bucket=%u, old=%p)", __func__, bucket, old)); 1051 1052 new->ip6q_prev = old; 1053 new->ip6q_next = old->ip6q_next; 1054 old->ip6q_next->ip6q_prev= new; 1055 old->ip6q_next = new; 1056 V_ip6qb[bucket].count++; 1057 } 1058 1059 static void 1060 frag6_remque(struct ip6q *p6, uint32_t bucket) 1061 { 1062 1063 IP6QB_LOCK_ASSERT(bucket); 1064 1065 p6->ip6q_prev->ip6q_next = p6->ip6q_next; 1066 p6->ip6q_next->ip6q_prev = p6->ip6q_prev; 1067 V_ip6qb[bucket].count--; 1068 } 1069