1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_bootp.h" 36 #include "opt_ipfw.h" 37 #include "opt_ipstealth.h" 38 #include "opt_ipsec.h" 39 #include "opt_route.h" 40 #include "opt_rss.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/mbuf.h> 45 #include <sys/malloc.h> 46 #include <sys/domain.h> 47 #include <sys/protosw.h> 48 #include <sys/socket.h> 49 #include <sys/time.h> 50 #include <sys/kernel.h> 51 #include <sys/lock.h> 52 #include <sys/rwlock.h> 53 #include <sys/sdt.h> 54 #include <sys/syslog.h> 55 #include <sys/sysctl.h> 56 57 #include <net/pfil.h> 58 #include <net/if.h> 59 #include <net/if_types.h> 60 #include <net/if_var.h> 61 #include <net/if_dl.h> 62 #include <net/route.h> 63 #include <net/netisr.h> 64 #include <net/vnet.h> 65 66 #include <netinet/in.h> 67 #include <netinet/in_kdtrace.h> 68 #include <netinet/in_systm.h> 69 #include <netinet/in_var.h> 70 #include <netinet/ip.h> 71 #include <netinet/in_pcb.h> 72 #include <netinet/ip_var.h> 73 #include <netinet/ip_fw.h> 74 #include <netinet/ip_icmp.h> 75 #include <netinet/ip_options.h> 76 #include <machine/in_cksum.h> 77 #include <netinet/ip_carp.h> 78 #ifdef IPSEC 79 #include <netinet/ip_ipsec.h> 80 #endif /* IPSEC */ 81 #include <netinet/in_rss.h> 82 83 #include <sys/socketvar.h> 84 85 #include <security/mac/mac_framework.h> 86 87 #ifdef CTASSERT 88 CTASSERT(sizeof(struct ip) == 20); 89 #endif 90 91 struct rwlock in_ifaddr_lock; 92 RW_SYSINIT(in_ifaddr_lock, &in_ifaddr_lock, "in_ifaddr_lock"); 93 94 VNET_DEFINE(int, rsvp_on); 95 96 VNET_DEFINE(int, ipforwarding); 97 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_VNET | CTLFLAG_RW, 98 &VNET_NAME(ipforwarding), 0, 99 "Enable IP forwarding between interfaces"); 100 101 static VNET_DEFINE(int, ipsendredirects) = 1; /* XXX */ 102 #define V_ipsendredirects VNET(ipsendredirects) 103 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_VNET | CTLFLAG_RW, 104 &VNET_NAME(ipsendredirects), 0, 105 "Enable sending IP redirects"); 106 107 static VNET_DEFINE(int, ip_sendsourcequench); 108 #define V_ip_sendsourcequench VNET(ip_sendsourcequench) 109 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_VNET | CTLFLAG_RW, 110 &VNET_NAME(ip_sendsourcequench), 0, 111 "Enable the transmission of source quench packets"); 112 113 VNET_DEFINE(int, ip_do_randomid); 114 SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_VNET | CTLFLAG_RW, 115 &VNET_NAME(ip_do_randomid), 0, 116 "Assign random ip_id values"); 117 118 /* 119 * XXX - Setting ip_checkinterface mostly implements the receive side of 120 * the Strong ES model described in RFC 1122, but since the routing table 121 * and transmit implementation do not implement the Strong ES model, 122 * setting this to 1 results in an odd hybrid. 123 * 124 * XXX - ip_checkinterface currently must be disabled if you use ipnat 125 * to translate the destination address to another local interface. 126 * 127 * XXX - ip_checkinterface must be disabled if you add IP aliases 128 * to the loopback interface instead of the interface where the 129 * packets for those addresses are received. 130 */ 131 static VNET_DEFINE(int, ip_checkinterface); 132 #define V_ip_checkinterface VNET(ip_checkinterface) 133 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_VNET | CTLFLAG_RW, 134 &VNET_NAME(ip_checkinterface), 0, 135 "Verify packet arrives on correct interface"); 136 137 VNET_DEFINE(struct pfil_head, inet_pfil_hook); /* Packet filter hooks */ 138 139 static struct netisr_handler ip_nh = { 140 .nh_name = "ip", 141 .nh_handler = ip_input, 142 .nh_proto = NETISR_IP, 143 #ifdef RSS 144 .nh_m2cpuid = rss_soft_m2cpuid, 145 .nh_policy = NETISR_POLICY_CPU, 146 .nh_dispatch = NETISR_DISPATCH_HYBRID, 147 #else 148 .nh_policy = NETISR_POLICY_FLOW, 149 #endif 150 }; 151 152 #ifdef RSS 153 /* 154 * Directly dispatched frames are currently assumed 155 * to have a flowid already calculated. 156 * 157 * It should likely have something that assert it 158 * actually has valid flow details. 159 */ 160 static struct netisr_handler ip_direct_nh = { 161 .nh_name = "ip_direct", 162 .nh_handler = ip_direct_input, 163 .nh_proto = NETISR_IP_DIRECT, 164 .nh_m2cpuid = rss_m2cpuid, 165 .nh_policy = NETISR_POLICY_CPU, 166 .nh_dispatch = NETISR_DISPATCH_HYBRID, 167 }; 168 #endif 169 170 extern struct domain inetdomain; 171 extern struct protosw inetsw[]; 172 u_char ip_protox[IPPROTO_MAX]; 173 VNET_DEFINE(struct in_ifaddrhead, in_ifaddrhead); /* first inet address */ 174 VNET_DEFINE(struct in_ifaddrhashhead *, in_ifaddrhashtbl); /* inet addr hash table */ 175 VNET_DEFINE(u_long, in_ifaddrhmask); /* mask for hash table */ 176 177 static VNET_DEFINE(uma_zone_t, ipq_zone); 178 static VNET_DEFINE(TAILQ_HEAD(ipqhead, ipq), ipq[IPREASS_NHASH]); 179 static struct mtx ipqlock; 180 181 #define V_ipq_zone VNET(ipq_zone) 182 #define V_ipq VNET(ipq) 183 184 #define IPQ_LOCK() mtx_lock(&ipqlock) 185 #define IPQ_UNLOCK() mtx_unlock(&ipqlock) 186 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF) 187 #define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED) 188 189 static void maxnipq_update(void); 190 static void ipq_zone_change(void *); 191 static void ip_drain_locked(void); 192 193 static VNET_DEFINE(int, maxnipq); /* Administrative limit on # reass queues. */ 194 static VNET_DEFINE(int, nipq); /* Total # of reass queues */ 195 #define V_maxnipq VNET(maxnipq) 196 #define V_nipq VNET(nipq) 197 SYSCTL_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET | CTLFLAG_RD, 198 &VNET_NAME(nipq), 0, 199 "Current number of IPv4 fragment reassembly queue entries"); 200 201 static VNET_DEFINE(int, maxfragsperpacket); 202 #define V_maxfragsperpacket VNET(maxfragsperpacket) 203 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW, 204 &VNET_NAME(maxfragsperpacket), 0, 205 "Maximum number of IPv4 fragments allowed per packet"); 206 207 #ifdef IPCTL_DEFMTU 208 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, 209 &ip_mtu, 0, "Default MTU"); 210 #endif 211 212 #ifdef IPSTEALTH 213 VNET_DEFINE(int, ipstealth); 214 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_VNET | CTLFLAG_RW, 215 &VNET_NAME(ipstealth), 0, 216 "IP stealth mode, no TTL decrementation on forwarding"); 217 #endif 218 219 static void ip_freef(struct ipqhead *, struct ipq *); 220 221 /* 222 * IP statistics are stored in the "array" of counter(9)s. 223 */ 224 VNET_PCPUSTAT_DEFINE(struct ipstat, ipstat); 225 VNET_PCPUSTAT_SYSINIT(ipstat); 226 SYSCTL_VNET_PCPUSTAT(_net_inet_ip, IPCTL_STATS, stats, struct ipstat, ipstat, 227 "IP statistics (struct ipstat, netinet/ip_var.h)"); 228 229 #ifdef VIMAGE 230 VNET_PCPUSTAT_SYSUNINIT(ipstat); 231 #endif /* VIMAGE */ 232 233 /* 234 * Kernel module interface for updating ipstat. The argument is an index 235 * into ipstat treated as an array. 236 */ 237 void 238 kmod_ipstat_inc(int statnum) 239 { 240 241 counter_u64_add(VNET(ipstat)[statnum], 1); 242 } 243 244 void 245 kmod_ipstat_dec(int statnum) 246 { 247 248 counter_u64_add(VNET(ipstat)[statnum], -1); 249 } 250 251 static int 252 sysctl_netinet_intr_queue_maxlen(SYSCTL_HANDLER_ARGS) 253 { 254 int error, qlimit; 255 256 netisr_getqlimit(&ip_nh, &qlimit); 257 error = sysctl_handle_int(oidp, &qlimit, 0, req); 258 if (error || !req->newptr) 259 return (error); 260 if (qlimit < 1) 261 return (EINVAL); 262 return (netisr_setqlimit(&ip_nh, qlimit)); 263 } 264 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, 265 CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_queue_maxlen, "I", 266 "Maximum size of the IP input queue"); 267 268 static int 269 sysctl_netinet_intr_queue_drops(SYSCTL_HANDLER_ARGS) 270 { 271 u_int64_t qdrops_long; 272 int error, qdrops; 273 274 netisr_getqdrops(&ip_nh, &qdrops_long); 275 qdrops = qdrops_long; 276 error = sysctl_handle_int(oidp, &qdrops, 0, req); 277 if (error || !req->newptr) 278 return (error); 279 if (qdrops != 0) 280 return (EINVAL); 281 netisr_clearqdrops(&ip_nh); 282 return (0); 283 } 284 285 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, 286 CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_queue_drops, "I", 287 "Number of packets dropped from the IP input queue"); 288 289 #ifdef RSS 290 static int 291 sysctl_netinet_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS) 292 { 293 int error, qlimit; 294 295 netisr_getqlimit(&ip_direct_nh, &qlimit); 296 error = sysctl_handle_int(oidp, &qlimit, 0, req); 297 if (error || !req->newptr) 298 return (error); 299 if (qlimit < 1) 300 return (EINVAL); 301 return (netisr_setqlimit(&ip_direct_nh, qlimit)); 302 } 303 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_direct_queue_maxlen, 304 CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_direct_queue_maxlen, "I", 305 "Maximum size of the IP direct input queue"); 306 307 static int 308 sysctl_netinet_intr_direct_queue_drops(SYSCTL_HANDLER_ARGS) 309 { 310 u_int64_t qdrops_long; 311 int error, qdrops; 312 313 netisr_getqdrops(&ip_direct_nh, &qdrops_long); 314 qdrops = qdrops_long; 315 error = sysctl_handle_int(oidp, &qdrops, 0, req); 316 if (error || !req->newptr) 317 return (error); 318 if (qdrops != 0) 319 return (EINVAL); 320 netisr_clearqdrops(&ip_direct_nh); 321 return (0); 322 } 323 324 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_direct_queue_drops, 325 CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_direct_queue_drops, "I", 326 "Number of packets dropped from the IP direct input queue"); 327 #endif /* RSS */ 328 329 /* 330 * IP initialization: fill in IP protocol switch table. 331 * All protocols not implemented in kernel go to raw IP protocol handler. 332 */ 333 void 334 ip_init(void) 335 { 336 struct protosw *pr; 337 int i; 338 339 V_ip_id = time_second & 0xffff; 340 341 TAILQ_INIT(&V_in_ifaddrhead); 342 V_in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &V_in_ifaddrhmask); 343 344 /* Initialize IP reassembly queue. */ 345 for (i = 0; i < IPREASS_NHASH; i++) 346 TAILQ_INIT(&V_ipq[i]); 347 V_maxnipq = nmbclusters / 32; 348 V_maxfragsperpacket = 16; 349 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL, 350 NULL, UMA_ALIGN_PTR, 0); 351 maxnipq_update(); 352 353 /* Initialize packet filter hooks. */ 354 V_inet_pfil_hook.ph_type = PFIL_TYPE_AF; 355 V_inet_pfil_hook.ph_af = AF_INET; 356 if ((i = pfil_head_register(&V_inet_pfil_hook)) != 0) 357 printf("%s: WARNING: unable to register pfil hook, " 358 "error %d\n", __func__, i); 359 360 /* Skip initialization of globals for non-default instances. */ 361 if (!IS_DEFAULT_VNET(curvnet)) 362 return; 363 364 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 365 if (pr == NULL) 366 panic("ip_init: PF_INET not found"); 367 368 /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */ 369 for (i = 0; i < IPPROTO_MAX; i++) 370 ip_protox[i] = pr - inetsw; 371 /* 372 * Cycle through IP protocols and put them into the appropriate place 373 * in ip_protox[]. 374 */ 375 for (pr = inetdomain.dom_protosw; 376 pr < inetdomain.dom_protoswNPROTOSW; pr++) 377 if (pr->pr_domain->dom_family == PF_INET && 378 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) { 379 /* Be careful to only index valid IP protocols. */ 380 if (pr->pr_protocol < IPPROTO_MAX) 381 ip_protox[pr->pr_protocol] = pr - inetsw; 382 } 383 384 EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change, 385 NULL, EVENTHANDLER_PRI_ANY); 386 387 /* Initialize various other remaining things. */ 388 IPQ_LOCK_INIT(); 389 netisr_register(&ip_nh); 390 #ifdef RSS 391 netisr_register(&ip_direct_nh); 392 #endif 393 } 394 395 #ifdef VIMAGE 396 void 397 ip_destroy(void) 398 { 399 int i; 400 401 if ((i = pfil_head_unregister(&V_inet_pfil_hook)) != 0) 402 printf("%s: WARNING: unable to unregister pfil hook, " 403 "error %d\n", __func__, i); 404 405 /* Cleanup in_ifaddr hash table; should be empty. */ 406 hashdestroy(V_in_ifaddrhashtbl, M_IFADDR, V_in_ifaddrhmask); 407 408 IPQ_LOCK(); 409 ip_drain_locked(); 410 IPQ_UNLOCK(); 411 412 uma_zdestroy(V_ipq_zone); 413 } 414 #endif 415 416 #ifdef RSS 417 /* 418 * IP direct input routine. 419 * 420 * This is called when reinjecting completed fragments where 421 * all of the previous checking and book-keeping has been done. 422 */ 423 void 424 ip_direct_input(struct mbuf *m) 425 { 426 struct ip *ip; 427 int hlen; 428 429 ip = mtod(m, struct ip *); 430 hlen = ip->ip_hl << 2; 431 432 IPSTAT_INC(ips_delivered); 433 (*inetsw[ip_protox[ip->ip_p]].pr_input)(&m, &hlen, ip->ip_p); 434 return; 435 } 436 #endif 437 438 /* 439 * Ip input routine. Checksum and byte swap header. If fragmented 440 * try to reassemble. Process options. Pass to next level. 441 */ 442 void 443 ip_input(struct mbuf *m) 444 { 445 struct ip *ip = NULL; 446 struct in_ifaddr *ia = NULL; 447 struct ifaddr *ifa; 448 struct ifnet *ifp; 449 int checkif, hlen = 0; 450 uint16_t sum, ip_len; 451 int dchg = 0; /* dest changed after fw */ 452 struct in_addr odst; /* original dst address */ 453 454 M_ASSERTPKTHDR(m); 455 456 if (m->m_flags & M_FASTFWD_OURS) { 457 m->m_flags &= ~M_FASTFWD_OURS; 458 /* Set up some basics that will be used later. */ 459 ip = mtod(m, struct ip *); 460 hlen = ip->ip_hl << 2; 461 ip_len = ntohs(ip->ip_len); 462 goto ours; 463 } 464 465 IPSTAT_INC(ips_total); 466 467 if (m->m_pkthdr.len < sizeof(struct ip)) 468 goto tooshort; 469 470 if (m->m_len < sizeof (struct ip) && 471 (m = m_pullup(m, sizeof (struct ip))) == NULL) { 472 IPSTAT_INC(ips_toosmall); 473 return; 474 } 475 ip = mtod(m, struct ip *); 476 477 if (ip->ip_v != IPVERSION) { 478 IPSTAT_INC(ips_badvers); 479 goto bad; 480 } 481 482 hlen = ip->ip_hl << 2; 483 if (hlen < sizeof(struct ip)) { /* minimum header length */ 484 IPSTAT_INC(ips_badhlen); 485 goto bad; 486 } 487 if (hlen > m->m_len) { 488 if ((m = m_pullup(m, hlen)) == NULL) { 489 IPSTAT_INC(ips_badhlen); 490 return; 491 } 492 ip = mtod(m, struct ip *); 493 } 494 495 IP_PROBE(receive, NULL, NULL, ip, m->m_pkthdr.rcvif, ip, NULL); 496 497 /* 127/8 must not appear on wire - RFC1122 */ 498 ifp = m->m_pkthdr.rcvif; 499 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 500 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 501 if ((ifp->if_flags & IFF_LOOPBACK) == 0) { 502 IPSTAT_INC(ips_badaddr); 503 goto bad; 504 } 505 } 506 507 if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) { 508 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 509 } else { 510 if (hlen == sizeof(struct ip)) { 511 sum = in_cksum_hdr(ip); 512 } else { 513 sum = in_cksum(m, hlen); 514 } 515 } 516 if (sum) { 517 IPSTAT_INC(ips_badsum); 518 goto bad; 519 } 520 521 #ifdef ALTQ 522 if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 523 /* packet is dropped by traffic conditioner */ 524 return; 525 #endif 526 527 ip_len = ntohs(ip->ip_len); 528 if (ip_len < hlen) { 529 IPSTAT_INC(ips_badlen); 530 goto bad; 531 } 532 533 /* 534 * Check that the amount of data in the buffers 535 * is as at least much as the IP header would have us expect. 536 * Trim mbufs if longer than we expect. 537 * Drop packet if shorter than we expect. 538 */ 539 if (m->m_pkthdr.len < ip_len) { 540 tooshort: 541 IPSTAT_INC(ips_tooshort); 542 goto bad; 543 } 544 if (m->m_pkthdr.len > ip_len) { 545 if (m->m_len == m->m_pkthdr.len) { 546 m->m_len = ip_len; 547 m->m_pkthdr.len = ip_len; 548 } else 549 m_adj(m, ip_len - m->m_pkthdr.len); 550 } 551 552 #ifdef IPSEC 553 /* 554 * Bypass packet filtering for packets previously handled by IPsec. 555 */ 556 if (ip_ipsec_filtertunnel(m)) 557 goto passin; 558 #endif /* IPSEC */ 559 560 /* 561 * Run through list of hooks for input packets. 562 * 563 * NB: Beware of the destination address changing (e.g. 564 * by NAT rewriting). When this happens, tell 565 * ip_forward to do the right thing. 566 */ 567 568 /* Jump over all PFIL processing if hooks are not active. */ 569 if (!PFIL_HOOKED(&V_inet_pfil_hook)) 570 goto passin; 571 572 odst = ip->ip_dst; 573 if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_IN, NULL) != 0) 574 return; 575 if (m == NULL) /* consumed by filter */ 576 return; 577 578 ip = mtod(m, struct ip *); 579 dchg = (odst.s_addr != ip->ip_dst.s_addr); 580 ifp = m->m_pkthdr.rcvif; 581 582 if (m->m_flags & M_FASTFWD_OURS) { 583 m->m_flags &= ~M_FASTFWD_OURS; 584 goto ours; 585 } 586 if (m->m_flags & M_IP_NEXTHOP) { 587 dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL); 588 if (dchg != 0) { 589 /* 590 * Directly ship the packet on. This allows 591 * forwarding packets originally destined to us 592 * to some other directly connected host. 593 */ 594 ip_forward(m, 1); 595 return; 596 } 597 } 598 passin: 599 600 /* 601 * Process options and, if not destined for us, 602 * ship it on. ip_dooptions returns 1 when an 603 * error was detected (causing an icmp message 604 * to be sent and the original packet to be freed). 605 */ 606 if (hlen > sizeof (struct ip) && ip_dooptions(m, 0)) 607 return; 608 609 /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no 610 * matter if it is destined to another node, or whether it is 611 * a multicast one, RSVP wants it! and prevents it from being forwarded 612 * anywhere else. Also checks if the rsvp daemon is running before 613 * grabbing the packet. 614 */ 615 if (V_rsvp_on && ip->ip_p==IPPROTO_RSVP) 616 goto ours; 617 618 /* 619 * Check our list of addresses, to see if the packet is for us. 620 * If we don't have any addresses, assume any unicast packet 621 * we receive might be for us (and let the upper layers deal 622 * with it). 623 */ 624 if (TAILQ_EMPTY(&V_in_ifaddrhead) && 625 (m->m_flags & (M_MCAST|M_BCAST)) == 0) 626 goto ours; 627 628 /* 629 * Enable a consistency check between the destination address 630 * and the arrival interface for a unicast packet (the RFC 1122 631 * strong ES model) if IP forwarding is disabled and the packet 632 * is not locally generated and the packet is not subject to 633 * 'ipfw fwd'. 634 * 635 * XXX - Checking also should be disabled if the destination 636 * address is ipnat'ed to a different interface. 637 * 638 * XXX - Checking is incompatible with IP aliases added 639 * to the loopback interface instead of the interface where 640 * the packets are received. 641 * 642 * XXX - This is the case for carp vhost IPs as well so we 643 * insert a workaround. If the packet got here, we already 644 * checked with carp_iamatch() and carp_forus(). 645 */ 646 checkif = V_ip_checkinterface && (V_ipforwarding == 0) && 647 ifp != NULL && ((ifp->if_flags & IFF_LOOPBACK) == 0) && 648 ifp->if_carp == NULL && (dchg == 0); 649 650 /* 651 * Check for exact addresses in the hash bucket. 652 */ 653 /* IN_IFADDR_RLOCK(); */ 654 LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) { 655 /* 656 * If the address matches, verify that the packet 657 * arrived via the correct interface if checking is 658 * enabled. 659 */ 660 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr && 661 (!checkif || ia->ia_ifp == ifp)) { 662 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 663 counter_u64_add(ia->ia_ifa.ifa_ibytes, 664 m->m_pkthdr.len); 665 /* IN_IFADDR_RUNLOCK(); */ 666 goto ours; 667 } 668 } 669 /* IN_IFADDR_RUNLOCK(); */ 670 671 /* 672 * Check for broadcast addresses. 673 * 674 * Only accept broadcast packets that arrive via the matching 675 * interface. Reception of forwarded directed broadcasts would 676 * be handled via ip_forward() and ether_output() with the loopback 677 * into the stack for SIMPLEX interfaces handled by ether_output(). 678 */ 679 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 680 IF_ADDR_RLOCK(ifp); 681 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 682 if (ifa->ifa_addr->sa_family != AF_INET) 683 continue; 684 ia = ifatoia(ifa); 685 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 686 ip->ip_dst.s_addr) { 687 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 688 counter_u64_add(ia->ia_ifa.ifa_ibytes, 689 m->m_pkthdr.len); 690 IF_ADDR_RUNLOCK(ifp); 691 goto ours; 692 } 693 #ifdef BOOTP_COMPAT 694 if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) { 695 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 696 counter_u64_add(ia->ia_ifa.ifa_ibytes, 697 m->m_pkthdr.len); 698 IF_ADDR_RUNLOCK(ifp); 699 goto ours; 700 } 701 #endif 702 } 703 IF_ADDR_RUNLOCK(ifp); 704 ia = NULL; 705 } 706 /* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */ 707 if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) { 708 IPSTAT_INC(ips_cantforward); 709 m_freem(m); 710 return; 711 } 712 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 713 if (V_ip_mrouter) { 714 /* 715 * If we are acting as a multicast router, all 716 * incoming multicast packets are passed to the 717 * kernel-level multicast forwarding function. 718 * The packet is returned (relatively) intact; if 719 * ip_mforward() returns a non-zero value, the packet 720 * must be discarded, else it may be accepted below. 721 */ 722 if (ip_mforward && ip_mforward(ip, ifp, m, 0) != 0) { 723 IPSTAT_INC(ips_cantforward); 724 m_freem(m); 725 return; 726 } 727 728 /* 729 * The process-level routing daemon needs to receive 730 * all multicast IGMP packets, whether or not this 731 * host belongs to their destination groups. 732 */ 733 if (ip->ip_p == IPPROTO_IGMP) 734 goto ours; 735 IPSTAT_INC(ips_forward); 736 } 737 /* 738 * Assume the packet is for us, to avoid prematurely taking 739 * a lock on the in_multi hash. Protocols must perform 740 * their own filtering and update statistics accordingly. 741 */ 742 goto ours; 743 } 744 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 745 goto ours; 746 if (ip->ip_dst.s_addr == INADDR_ANY) 747 goto ours; 748 749 /* 750 * Not for us; forward if possible and desirable. 751 */ 752 if (V_ipforwarding == 0) { 753 IPSTAT_INC(ips_cantforward); 754 m_freem(m); 755 } else { 756 #ifdef IPSEC 757 if (ip_ipsec_fwd(m)) 758 goto bad; 759 #endif /* IPSEC */ 760 ip_forward(m, dchg); 761 } 762 return; 763 764 ours: 765 #ifdef IPSTEALTH 766 /* 767 * IPSTEALTH: Process non-routing options only 768 * if the packet is destined for us. 769 */ 770 if (V_ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1)) 771 return; 772 #endif /* IPSTEALTH */ 773 774 /* 775 * Attempt reassembly; if it succeeds, proceed. 776 * ip_reass() will return a different mbuf. 777 */ 778 if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) { 779 /* XXXGL: shouldn't we save & set m_flags? */ 780 m = ip_reass(m); 781 if (m == NULL) 782 return; 783 ip = mtod(m, struct ip *); 784 /* Get the header length of the reassembled packet */ 785 hlen = ip->ip_hl << 2; 786 } 787 788 #ifdef IPSEC 789 /* 790 * enforce IPsec policy checking if we are seeing last header. 791 * note that we do not visit this with protocols with pcb layer 792 * code - like udp/tcp/raw ip. 793 */ 794 if (ip_ipsec_input(m)) 795 goto bad; 796 #endif /* IPSEC */ 797 798 /* 799 * Switch out to protocol's input routine. 800 */ 801 IPSTAT_INC(ips_delivered); 802 803 (*inetsw[ip_protox[ip->ip_p]].pr_input)(&m, &hlen, ip->ip_p); 804 return; 805 bad: 806 m_freem(m); 807 } 808 809 /* 810 * After maxnipq has been updated, propagate the change to UMA. The UMA zone 811 * max has slightly different semantics than the sysctl, for historical 812 * reasons. 813 */ 814 static void 815 maxnipq_update(void) 816 { 817 818 /* 819 * -1 for unlimited allocation. 820 */ 821 if (V_maxnipq < 0) 822 uma_zone_set_max(V_ipq_zone, 0); 823 /* 824 * Positive number for specific bound. 825 */ 826 if (V_maxnipq > 0) 827 uma_zone_set_max(V_ipq_zone, V_maxnipq); 828 /* 829 * Zero specifies no further fragment queue allocation -- set the 830 * bound very low, but rely on implementation elsewhere to actually 831 * prevent allocation and reclaim current queues. 832 */ 833 if (V_maxnipq == 0) 834 uma_zone_set_max(V_ipq_zone, 1); 835 } 836 837 static void 838 ipq_zone_change(void *tag) 839 { 840 841 if (V_maxnipq > 0 && V_maxnipq < (nmbclusters / 32)) { 842 V_maxnipq = nmbclusters / 32; 843 maxnipq_update(); 844 } 845 } 846 847 static int 848 sysctl_maxnipq(SYSCTL_HANDLER_ARGS) 849 { 850 int error, i; 851 852 i = V_maxnipq; 853 error = sysctl_handle_int(oidp, &i, 0, req); 854 if (error || !req->newptr) 855 return (error); 856 857 /* 858 * XXXRW: Might be a good idea to sanity check the argument and place 859 * an extreme upper bound. 860 */ 861 if (i < -1) 862 return (EINVAL); 863 V_maxnipq = i; 864 maxnipq_update(); 865 return (0); 866 } 867 868 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW, 869 NULL, 0, sysctl_maxnipq, "I", 870 "Maximum number of IPv4 fragment reassembly queue entries"); 871 872 #define M_IP_FRAG M_PROTO9 873 874 /* 875 * Take incoming datagram fragment and try to reassemble it into 876 * whole datagram. If the argument is the first fragment or one 877 * in between the function will return NULL and store the mbuf 878 * in the fragment chain. If the argument is the last fragment 879 * the packet will be reassembled and the pointer to the new 880 * mbuf returned for further processing. Only m_tags attached 881 * to the first packet/fragment are preserved. 882 * The IP header is *NOT* adjusted out of iplen. 883 */ 884 struct mbuf * 885 ip_reass(struct mbuf *m) 886 { 887 struct ip *ip; 888 struct mbuf *p, *q, *nq, *t; 889 struct ipq *fp = NULL; 890 struct ipqhead *head; 891 int i, hlen, next; 892 u_int8_t ecn, ecn0; 893 u_short hash; 894 #ifdef RSS 895 uint32_t rss_hash, rss_type; 896 #endif 897 898 /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */ 899 if (V_maxnipq == 0 || V_maxfragsperpacket == 0) { 900 IPSTAT_INC(ips_fragments); 901 IPSTAT_INC(ips_fragdropped); 902 m_freem(m); 903 return (NULL); 904 } 905 906 ip = mtod(m, struct ip *); 907 hlen = ip->ip_hl << 2; 908 909 hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); 910 head = &V_ipq[hash]; 911 IPQ_LOCK(); 912 913 /* 914 * Look for queue of fragments 915 * of this datagram. 916 */ 917 TAILQ_FOREACH(fp, head, ipq_list) 918 if (ip->ip_id == fp->ipq_id && 919 ip->ip_src.s_addr == fp->ipq_src.s_addr && 920 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 921 #ifdef MAC 922 mac_ipq_match(m, fp) && 923 #endif 924 ip->ip_p == fp->ipq_p) 925 goto found; 926 927 fp = NULL; 928 929 /* 930 * Attempt to trim the number of allocated fragment queues if it 931 * exceeds the administrative limit. 932 */ 933 if ((V_nipq > V_maxnipq) && (V_maxnipq > 0)) { 934 /* 935 * drop something from the tail of the current queue 936 * before proceeding further 937 */ 938 struct ipq *q = TAILQ_LAST(head, ipqhead); 939 if (q == NULL) { /* gak */ 940 for (i = 0; i < IPREASS_NHASH; i++) { 941 struct ipq *r = TAILQ_LAST(&V_ipq[i], ipqhead); 942 if (r) { 943 IPSTAT_ADD(ips_fragtimeout, 944 r->ipq_nfrags); 945 ip_freef(&V_ipq[i], r); 946 break; 947 } 948 } 949 } else { 950 IPSTAT_ADD(ips_fragtimeout, q->ipq_nfrags); 951 ip_freef(head, q); 952 } 953 } 954 955 found: 956 /* 957 * Adjust ip_len to not reflect header, 958 * convert offset of this to bytes. 959 */ 960 ip->ip_len = htons(ntohs(ip->ip_len) - hlen); 961 if (ip->ip_off & htons(IP_MF)) { 962 /* 963 * Make sure that fragments have a data length 964 * that's a non-zero multiple of 8 bytes. 965 */ 966 if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) { 967 IPSTAT_INC(ips_toosmall); /* XXX */ 968 goto dropfrag; 969 } 970 m->m_flags |= M_IP_FRAG; 971 } else 972 m->m_flags &= ~M_IP_FRAG; 973 ip->ip_off = htons(ntohs(ip->ip_off) << 3); 974 975 /* 976 * Attempt reassembly; if it succeeds, proceed. 977 * ip_reass() will return a different mbuf. 978 */ 979 IPSTAT_INC(ips_fragments); 980 m->m_pkthdr.PH_loc.ptr = ip; 981 982 /* Previous ip_reass() started here. */ 983 /* 984 * Presence of header sizes in mbufs 985 * would confuse code below. 986 */ 987 m->m_data += hlen; 988 m->m_len -= hlen; 989 990 /* 991 * If first fragment to arrive, create a reassembly queue. 992 */ 993 if (fp == NULL) { 994 fp = uma_zalloc(V_ipq_zone, M_NOWAIT); 995 if (fp == NULL) 996 goto dropfrag; 997 #ifdef MAC 998 if (mac_ipq_init(fp, M_NOWAIT) != 0) { 999 uma_zfree(V_ipq_zone, fp); 1000 fp = NULL; 1001 goto dropfrag; 1002 } 1003 mac_ipq_create(m, fp); 1004 #endif 1005 TAILQ_INSERT_HEAD(head, fp, ipq_list); 1006 V_nipq++; 1007 fp->ipq_nfrags = 1; 1008 fp->ipq_ttl = IPFRAGTTL; 1009 fp->ipq_p = ip->ip_p; 1010 fp->ipq_id = ip->ip_id; 1011 fp->ipq_src = ip->ip_src; 1012 fp->ipq_dst = ip->ip_dst; 1013 fp->ipq_frags = m; 1014 m->m_nextpkt = NULL; 1015 goto done; 1016 } else { 1017 fp->ipq_nfrags++; 1018 #ifdef MAC 1019 mac_ipq_update(m, fp); 1020 #endif 1021 } 1022 1023 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr)) 1024 1025 /* 1026 * Handle ECN by comparing this segment with the first one; 1027 * if CE is set, do not lose CE. 1028 * drop if CE and not-ECT are mixed for the same packet. 1029 */ 1030 ecn = ip->ip_tos & IPTOS_ECN_MASK; 1031 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; 1032 if (ecn == IPTOS_ECN_CE) { 1033 if (ecn0 == IPTOS_ECN_NOTECT) 1034 goto dropfrag; 1035 if (ecn0 != IPTOS_ECN_CE) 1036 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE; 1037 } 1038 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) 1039 goto dropfrag; 1040 1041 /* 1042 * Find a segment which begins after this one does. 1043 */ 1044 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) 1045 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off)) 1046 break; 1047 1048 /* 1049 * If there is a preceding segment, it may provide some of 1050 * our data already. If so, drop the data from the incoming 1051 * segment. If it provides all of our data, drop us, otherwise 1052 * stick new segment in the proper place. 1053 * 1054 * If some of the data is dropped from the preceding 1055 * segment, then it's checksum is invalidated. 1056 */ 1057 if (p) { 1058 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) - 1059 ntohs(ip->ip_off); 1060 if (i > 0) { 1061 if (i >= ntohs(ip->ip_len)) 1062 goto dropfrag; 1063 m_adj(m, i); 1064 m->m_pkthdr.csum_flags = 0; 1065 ip->ip_off = htons(ntohs(ip->ip_off) + i); 1066 ip->ip_len = htons(ntohs(ip->ip_len) - i); 1067 } 1068 m->m_nextpkt = p->m_nextpkt; 1069 p->m_nextpkt = m; 1070 } else { 1071 m->m_nextpkt = fp->ipq_frags; 1072 fp->ipq_frags = m; 1073 } 1074 1075 /* 1076 * While we overlap succeeding segments trim them or, 1077 * if they are completely covered, dequeue them. 1078 */ 1079 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) > 1080 ntohs(GETIP(q)->ip_off); q = nq) { 1081 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) - 1082 ntohs(GETIP(q)->ip_off); 1083 if (i < ntohs(GETIP(q)->ip_len)) { 1084 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i); 1085 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i); 1086 m_adj(q, i); 1087 q->m_pkthdr.csum_flags = 0; 1088 break; 1089 } 1090 nq = q->m_nextpkt; 1091 m->m_nextpkt = nq; 1092 IPSTAT_INC(ips_fragdropped); 1093 fp->ipq_nfrags--; 1094 m_freem(q); 1095 } 1096 1097 /* 1098 * Check for complete reassembly and perform frag per packet 1099 * limiting. 1100 * 1101 * Frag limiting is performed here so that the nth frag has 1102 * a chance to complete the packet before we drop the packet. 1103 * As a result, n+1 frags are actually allowed per packet, but 1104 * only n will ever be stored. (n = maxfragsperpacket.) 1105 * 1106 */ 1107 next = 0; 1108 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { 1109 if (ntohs(GETIP(q)->ip_off) != next) { 1110 if (fp->ipq_nfrags > V_maxfragsperpacket) { 1111 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1112 ip_freef(head, fp); 1113 } 1114 goto done; 1115 } 1116 next += ntohs(GETIP(q)->ip_len); 1117 } 1118 /* Make sure the last packet didn't have the IP_MF flag */ 1119 if (p->m_flags & M_IP_FRAG) { 1120 if (fp->ipq_nfrags > V_maxfragsperpacket) { 1121 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1122 ip_freef(head, fp); 1123 } 1124 goto done; 1125 } 1126 1127 /* 1128 * Reassembly is complete. Make sure the packet is a sane size. 1129 */ 1130 q = fp->ipq_frags; 1131 ip = GETIP(q); 1132 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { 1133 IPSTAT_INC(ips_toolong); 1134 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1135 ip_freef(head, fp); 1136 goto done; 1137 } 1138 1139 /* 1140 * Concatenate fragments. 1141 */ 1142 m = q; 1143 t = m->m_next; 1144 m->m_next = NULL; 1145 m_cat(m, t); 1146 nq = q->m_nextpkt; 1147 q->m_nextpkt = NULL; 1148 for (q = nq; q != NULL; q = nq) { 1149 nq = q->m_nextpkt; 1150 q->m_nextpkt = NULL; 1151 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; 1152 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; 1153 m_cat(m, q); 1154 } 1155 /* 1156 * In order to do checksumming faster we do 'end-around carry' here 1157 * (and not in for{} loop), though it implies we are not going to 1158 * reassemble more than 64k fragments. 1159 */ 1160 while (m->m_pkthdr.csum_data & 0xffff0000) 1161 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 1162 (m->m_pkthdr.csum_data >> 16); 1163 #ifdef MAC 1164 mac_ipq_reassemble(fp, m); 1165 mac_ipq_destroy(fp); 1166 #endif 1167 1168 /* 1169 * Create header for new ip packet by modifying header of first 1170 * packet; dequeue and discard fragment reassembly header. 1171 * Make header visible. 1172 */ 1173 ip->ip_len = htons((ip->ip_hl << 2) + next); 1174 ip->ip_src = fp->ipq_src; 1175 ip->ip_dst = fp->ipq_dst; 1176 TAILQ_REMOVE(head, fp, ipq_list); 1177 V_nipq--; 1178 uma_zfree(V_ipq_zone, fp); 1179 m->m_len += (ip->ip_hl << 2); 1180 m->m_data -= (ip->ip_hl << 2); 1181 /* some debugging cruft by sklower, below, will go away soon */ 1182 if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */ 1183 m_fixhdr(m); 1184 IPSTAT_INC(ips_reassembled); 1185 IPQ_UNLOCK(); 1186 1187 #ifdef RSS 1188 /* 1189 * Query the RSS layer for the flowid / flowtype for the 1190 * mbuf payload. 1191 * 1192 * For now, just assume we have to calculate a new one. 1193 * Later on we should check to see if the assigned flowid matches 1194 * what RSS wants for the given IP protocol and if so, just keep it. 1195 * 1196 * We then queue into the relevant netisr so it can be dispatched 1197 * to the correct CPU. 1198 * 1199 * Note - this may return 1, which means the flowid in the mbuf 1200 * is correct for the configured RSS hash types and can be used. 1201 */ 1202 if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) { 1203 m->m_pkthdr.flowid = rss_hash; 1204 M_HASHTYPE_SET(m, rss_type); 1205 m->m_flags |= M_FLOWID; 1206 } 1207 1208 /* 1209 * Queue/dispatch for reprocessing. 1210 * 1211 * Note: this is much slower than just handling the frame in the 1212 * current receive context. It's likely worth investigating 1213 * why this is. 1214 */ 1215 netisr_dispatch(NETISR_IP_DIRECT, m); 1216 return (NULL); 1217 #endif 1218 1219 /* Handle in-line */ 1220 return (m); 1221 1222 dropfrag: 1223 IPSTAT_INC(ips_fragdropped); 1224 if (fp != NULL) 1225 fp->ipq_nfrags--; 1226 m_freem(m); 1227 done: 1228 IPQ_UNLOCK(); 1229 return (NULL); 1230 1231 #undef GETIP 1232 } 1233 1234 /* 1235 * Free a fragment reassembly header and all 1236 * associated datagrams. 1237 */ 1238 static void 1239 ip_freef(struct ipqhead *fhp, struct ipq *fp) 1240 { 1241 struct mbuf *q; 1242 1243 IPQ_LOCK_ASSERT(); 1244 1245 while (fp->ipq_frags) { 1246 q = fp->ipq_frags; 1247 fp->ipq_frags = q->m_nextpkt; 1248 m_freem(q); 1249 } 1250 TAILQ_REMOVE(fhp, fp, ipq_list); 1251 uma_zfree(V_ipq_zone, fp); 1252 V_nipq--; 1253 } 1254 1255 /* 1256 * IP timer processing; 1257 * if a timer expires on a reassembly 1258 * queue, discard it. 1259 */ 1260 void 1261 ip_slowtimo(void) 1262 { 1263 VNET_ITERATOR_DECL(vnet_iter); 1264 struct ipq *fp; 1265 int i; 1266 1267 VNET_LIST_RLOCK_NOSLEEP(); 1268 IPQ_LOCK(); 1269 VNET_FOREACH(vnet_iter) { 1270 CURVNET_SET(vnet_iter); 1271 for (i = 0; i < IPREASS_NHASH; i++) { 1272 for(fp = TAILQ_FIRST(&V_ipq[i]); fp;) { 1273 struct ipq *fpp; 1274 1275 fpp = fp; 1276 fp = TAILQ_NEXT(fp, ipq_list); 1277 if(--fpp->ipq_ttl == 0) { 1278 IPSTAT_ADD(ips_fragtimeout, 1279 fpp->ipq_nfrags); 1280 ip_freef(&V_ipq[i], fpp); 1281 } 1282 } 1283 } 1284 /* 1285 * If we are over the maximum number of fragments 1286 * (due to the limit being lowered), drain off 1287 * enough to get down to the new limit. 1288 */ 1289 if (V_maxnipq >= 0 && V_nipq > V_maxnipq) { 1290 for (i = 0; i < IPREASS_NHASH; i++) { 1291 while (V_nipq > V_maxnipq && 1292 !TAILQ_EMPTY(&V_ipq[i])) { 1293 IPSTAT_ADD(ips_fragdropped, 1294 TAILQ_FIRST(&V_ipq[i])->ipq_nfrags); 1295 ip_freef(&V_ipq[i], 1296 TAILQ_FIRST(&V_ipq[i])); 1297 } 1298 } 1299 } 1300 CURVNET_RESTORE(); 1301 } 1302 IPQ_UNLOCK(); 1303 VNET_LIST_RUNLOCK_NOSLEEP(); 1304 } 1305 1306 /* 1307 * Drain off all datagram fragments. 1308 */ 1309 static void 1310 ip_drain_locked(void) 1311 { 1312 int i; 1313 1314 IPQ_LOCK_ASSERT(); 1315 1316 for (i = 0; i < IPREASS_NHASH; i++) { 1317 while(!TAILQ_EMPTY(&V_ipq[i])) { 1318 IPSTAT_ADD(ips_fragdropped, 1319 TAILQ_FIRST(&V_ipq[i])->ipq_nfrags); 1320 ip_freef(&V_ipq[i], TAILQ_FIRST(&V_ipq[i])); 1321 } 1322 } 1323 } 1324 1325 void 1326 ip_drain(void) 1327 { 1328 VNET_ITERATOR_DECL(vnet_iter); 1329 1330 VNET_LIST_RLOCK_NOSLEEP(); 1331 IPQ_LOCK(); 1332 VNET_FOREACH(vnet_iter) { 1333 CURVNET_SET(vnet_iter); 1334 ip_drain_locked(); 1335 CURVNET_RESTORE(); 1336 } 1337 IPQ_UNLOCK(); 1338 VNET_LIST_RUNLOCK_NOSLEEP(); 1339 in_rtqdrain(); 1340 } 1341 1342 /* 1343 * The protocol to be inserted into ip_protox[] must be already registered 1344 * in inetsw[], either statically or through pf_proto_register(). 1345 */ 1346 int 1347 ipproto_register(short ipproto) 1348 { 1349 struct protosw *pr; 1350 1351 /* Sanity checks. */ 1352 if (ipproto <= 0 || ipproto >= IPPROTO_MAX) 1353 return (EPROTONOSUPPORT); 1354 1355 /* 1356 * The protocol slot must not be occupied by another protocol 1357 * already. An index pointing to IPPROTO_RAW is unused. 1358 */ 1359 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1360 if (pr == NULL) 1361 return (EPFNOSUPPORT); 1362 if (ip_protox[ipproto] != pr - inetsw) /* IPPROTO_RAW */ 1363 return (EEXIST); 1364 1365 /* Find the protocol position in inetsw[] and set the index. */ 1366 for (pr = inetdomain.dom_protosw; 1367 pr < inetdomain.dom_protoswNPROTOSW; pr++) { 1368 if (pr->pr_domain->dom_family == PF_INET && 1369 pr->pr_protocol && pr->pr_protocol == ipproto) { 1370 ip_protox[pr->pr_protocol] = pr - inetsw; 1371 return (0); 1372 } 1373 } 1374 return (EPROTONOSUPPORT); 1375 } 1376 1377 int 1378 ipproto_unregister(short ipproto) 1379 { 1380 struct protosw *pr; 1381 1382 /* Sanity checks. */ 1383 if (ipproto <= 0 || ipproto >= IPPROTO_MAX) 1384 return (EPROTONOSUPPORT); 1385 1386 /* Check if the protocol was indeed registered. */ 1387 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1388 if (pr == NULL) 1389 return (EPFNOSUPPORT); 1390 if (ip_protox[ipproto] == pr - inetsw) /* IPPROTO_RAW */ 1391 return (ENOENT); 1392 1393 /* Reset the protocol slot to IPPROTO_RAW. */ 1394 ip_protox[ipproto] = pr - inetsw; 1395 return (0); 1396 } 1397 1398 /* 1399 * Given address of next destination (final or next hop), return (referenced) 1400 * internet address info of interface to be used to get there. 1401 */ 1402 struct in_ifaddr * 1403 ip_rtaddr(struct in_addr dst, u_int fibnum) 1404 { 1405 struct route sro; 1406 struct sockaddr_in *sin; 1407 struct in_ifaddr *ia; 1408 1409 bzero(&sro, sizeof(sro)); 1410 sin = (struct sockaddr_in *)&sro.ro_dst; 1411 sin->sin_family = AF_INET; 1412 sin->sin_len = sizeof(*sin); 1413 sin->sin_addr = dst; 1414 in_rtalloc_ign(&sro, 0, fibnum); 1415 1416 if (sro.ro_rt == NULL) 1417 return (NULL); 1418 1419 ia = ifatoia(sro.ro_rt->rt_ifa); 1420 ifa_ref(&ia->ia_ifa); 1421 RTFREE(sro.ro_rt); 1422 return (ia); 1423 } 1424 1425 u_char inetctlerrmap[PRC_NCMDS] = { 1426 0, 0, 0, 0, 1427 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 1428 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 1429 EMSGSIZE, EHOSTUNREACH, 0, 0, 1430 0, 0, EHOSTUNREACH, 0, 1431 ENOPROTOOPT, ECONNREFUSED 1432 }; 1433 1434 /* 1435 * Forward a packet. If some error occurs return the sender 1436 * an icmp packet. Note we can't always generate a meaningful 1437 * icmp message because icmp doesn't have a large enough repertoire 1438 * of codes and types. 1439 * 1440 * If not forwarding, just drop the packet. This could be confusing 1441 * if ipforwarding was zero but some routing protocol was advancing 1442 * us as a gateway to somewhere. However, we must let the routing 1443 * protocol deal with that. 1444 * 1445 * The srcrt parameter indicates whether the packet is being forwarded 1446 * via a source route. 1447 */ 1448 void 1449 ip_forward(struct mbuf *m, int srcrt) 1450 { 1451 struct ip *ip = mtod(m, struct ip *); 1452 struct in_ifaddr *ia; 1453 struct mbuf *mcopy; 1454 struct in_addr dest; 1455 struct route ro; 1456 int error, type = 0, code = 0, mtu = 0; 1457 1458 if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) { 1459 IPSTAT_INC(ips_cantforward); 1460 m_freem(m); 1461 return; 1462 } 1463 #ifdef IPSTEALTH 1464 if (!V_ipstealth) { 1465 #endif 1466 if (ip->ip_ttl <= IPTTLDEC) { 1467 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 1468 0, 0); 1469 return; 1470 } 1471 #ifdef IPSTEALTH 1472 } 1473 #endif 1474 1475 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 1476 #ifndef IPSEC 1477 /* 1478 * 'ia' may be NULL if there is no route for this destination. 1479 * In case of IPsec, Don't discard it just yet, but pass it to 1480 * ip_output in case of outgoing IPsec policy. 1481 */ 1482 if (!srcrt && ia == NULL) { 1483 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 1484 return; 1485 } 1486 #endif 1487 1488 /* 1489 * Save the IP header and at most 8 bytes of the payload, 1490 * in case we need to generate an ICMP message to the src. 1491 * 1492 * XXX this can be optimized a lot by saving the data in a local 1493 * buffer on the stack (72 bytes at most), and only allocating the 1494 * mbuf if really necessary. The vast majority of the packets 1495 * are forwarded without having to send an ICMP back (either 1496 * because unnecessary, or because rate limited), so we are 1497 * really we are wasting a lot of work here. 1498 * 1499 * We don't use m_copy() because it might return a reference 1500 * to a shared cluster. Both this function and ip_output() 1501 * assume exclusive access to the IP header in `m', so any 1502 * data in a cluster may change before we reach icmp_error(). 1503 */ 1504 mcopy = m_gethdr(M_NOWAIT, m->m_type); 1505 if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_NOWAIT)) { 1506 /* 1507 * It's probably ok if the pkthdr dup fails (because 1508 * the deep copy of the tag chain failed), but for now 1509 * be conservative and just discard the copy since 1510 * code below may some day want the tags. 1511 */ 1512 m_free(mcopy); 1513 mcopy = NULL; 1514 } 1515 if (mcopy != NULL) { 1516 mcopy->m_len = min(ntohs(ip->ip_len), M_TRAILINGSPACE(mcopy)); 1517 mcopy->m_pkthdr.len = mcopy->m_len; 1518 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t)); 1519 } 1520 1521 #ifdef IPSTEALTH 1522 if (!V_ipstealth) { 1523 #endif 1524 ip->ip_ttl -= IPTTLDEC; 1525 #ifdef IPSTEALTH 1526 } 1527 #endif 1528 1529 /* 1530 * If forwarding packet using same interface that it came in on, 1531 * perhaps should send a redirect to sender to shortcut a hop. 1532 * Only send redirect if source is sending directly to us, 1533 * and if packet was not source routed (or has any options). 1534 * Also, don't send redirect if forwarding using a default route 1535 * or a route modified by a redirect. 1536 */ 1537 dest.s_addr = 0; 1538 if (!srcrt && V_ipsendredirects && 1539 ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) { 1540 struct sockaddr_in *sin; 1541 struct rtentry *rt; 1542 1543 bzero(&ro, sizeof(ro)); 1544 sin = (struct sockaddr_in *)&ro.ro_dst; 1545 sin->sin_family = AF_INET; 1546 sin->sin_len = sizeof(*sin); 1547 sin->sin_addr = ip->ip_dst; 1548 in_rtalloc_ign(&ro, 0, M_GETFIB(m)); 1549 1550 rt = ro.ro_rt; 1551 1552 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1553 satosin(rt_key(rt))->sin_addr.s_addr != 0) { 1554 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1555 u_long src = ntohl(ip->ip_src.s_addr); 1556 1557 if (RTA(rt) && 1558 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1559 if (rt->rt_flags & RTF_GATEWAY) 1560 dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr; 1561 else 1562 dest.s_addr = ip->ip_dst.s_addr; 1563 /* Router requirements says to only send host redirects */ 1564 type = ICMP_REDIRECT; 1565 code = ICMP_REDIRECT_HOST; 1566 } 1567 } 1568 if (rt) 1569 RTFREE(rt); 1570 } 1571 1572 /* 1573 * Try to cache the route MTU from ip_output so we can consider it for 1574 * the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191. 1575 */ 1576 bzero(&ro, sizeof(ro)); 1577 1578 error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL); 1579 1580 if (error == EMSGSIZE && ro.ro_rt) 1581 mtu = ro.ro_rt->rt_mtu; 1582 RO_RTFREE(&ro); 1583 1584 if (error) 1585 IPSTAT_INC(ips_cantforward); 1586 else { 1587 IPSTAT_INC(ips_forward); 1588 if (type) 1589 IPSTAT_INC(ips_redirectsent); 1590 else { 1591 if (mcopy) 1592 m_freem(mcopy); 1593 if (ia != NULL) 1594 ifa_free(&ia->ia_ifa); 1595 return; 1596 } 1597 } 1598 if (mcopy == NULL) { 1599 if (ia != NULL) 1600 ifa_free(&ia->ia_ifa); 1601 return; 1602 } 1603 1604 switch (error) { 1605 1606 case 0: /* forwarded, but need redirect */ 1607 /* type, code set above */ 1608 break; 1609 1610 case ENETUNREACH: 1611 case EHOSTUNREACH: 1612 case ENETDOWN: 1613 case EHOSTDOWN: 1614 default: 1615 type = ICMP_UNREACH; 1616 code = ICMP_UNREACH_HOST; 1617 break; 1618 1619 case EMSGSIZE: 1620 type = ICMP_UNREACH; 1621 code = ICMP_UNREACH_NEEDFRAG; 1622 1623 #ifdef IPSEC 1624 /* 1625 * If IPsec is configured for this path, 1626 * override any possibly mtu value set by ip_output. 1627 */ 1628 mtu = ip_ipsec_mtu(mcopy, mtu); 1629 #endif /* IPSEC */ 1630 /* 1631 * If the MTU was set before make sure we are below the 1632 * interface MTU. 1633 * If the MTU wasn't set before use the interface mtu or 1634 * fall back to the next smaller mtu step compared to the 1635 * current packet size. 1636 */ 1637 if (mtu != 0) { 1638 if (ia != NULL) 1639 mtu = min(mtu, ia->ia_ifp->if_mtu); 1640 } else { 1641 if (ia != NULL) 1642 mtu = ia->ia_ifp->if_mtu; 1643 else 1644 mtu = ip_next_mtu(ntohs(ip->ip_len), 0); 1645 } 1646 IPSTAT_INC(ips_cantfrag); 1647 break; 1648 1649 case ENOBUFS: 1650 /* 1651 * A router should not generate ICMP_SOURCEQUENCH as 1652 * required in RFC1812 Requirements for IP Version 4 Routers. 1653 * Source quench could be a big problem under DoS attacks, 1654 * or if the underlying interface is rate-limited. 1655 * Those who need source quench packets may re-enable them 1656 * via the net.inet.ip.sendsourcequench sysctl. 1657 */ 1658 if (V_ip_sendsourcequench == 0) { 1659 m_freem(mcopy); 1660 if (ia != NULL) 1661 ifa_free(&ia->ia_ifa); 1662 return; 1663 } else { 1664 type = ICMP_SOURCEQUENCH; 1665 code = 0; 1666 } 1667 break; 1668 1669 case EACCES: /* ipfw denied packet */ 1670 m_freem(mcopy); 1671 if (ia != NULL) 1672 ifa_free(&ia->ia_ifa); 1673 return; 1674 } 1675 if (ia != NULL) 1676 ifa_free(&ia->ia_ifa); 1677 icmp_error(mcopy, type, code, dest.s_addr, mtu); 1678 } 1679 1680 void 1681 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip, 1682 struct mbuf *m) 1683 { 1684 1685 if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) { 1686 struct bintime bt; 1687 1688 bintime(&bt); 1689 if (inp->inp_socket->so_options & SO_BINTIME) { 1690 *mp = sbcreatecontrol((caddr_t)&bt, sizeof(bt), 1691 SCM_BINTIME, SOL_SOCKET); 1692 if (*mp) 1693 mp = &(*mp)->m_next; 1694 } 1695 if (inp->inp_socket->so_options & SO_TIMESTAMP) { 1696 struct timeval tv; 1697 1698 bintime2timeval(&bt, &tv); 1699 *mp = sbcreatecontrol((caddr_t)&tv, sizeof(tv), 1700 SCM_TIMESTAMP, SOL_SOCKET); 1701 if (*mp) 1702 mp = &(*mp)->m_next; 1703 } 1704 } 1705 if (inp->inp_flags & INP_RECVDSTADDR) { 1706 *mp = sbcreatecontrol((caddr_t)&ip->ip_dst, 1707 sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP); 1708 if (*mp) 1709 mp = &(*mp)->m_next; 1710 } 1711 if (inp->inp_flags & INP_RECVTTL) { 1712 *mp = sbcreatecontrol((caddr_t)&ip->ip_ttl, 1713 sizeof(u_char), IP_RECVTTL, IPPROTO_IP); 1714 if (*mp) 1715 mp = &(*mp)->m_next; 1716 } 1717 #ifdef notyet 1718 /* XXX 1719 * Moving these out of udp_input() made them even more broken 1720 * than they already were. 1721 */ 1722 /* options were tossed already */ 1723 if (inp->inp_flags & INP_RECVOPTS) { 1724 *mp = sbcreatecontrol((caddr_t)opts_deleted_above, 1725 sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP); 1726 if (*mp) 1727 mp = &(*mp)->m_next; 1728 } 1729 /* ip_srcroute doesn't do what we want here, need to fix */ 1730 if (inp->inp_flags & INP_RECVRETOPTS) { 1731 *mp = sbcreatecontrol((caddr_t)ip_srcroute(m), 1732 sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP); 1733 if (*mp) 1734 mp = &(*mp)->m_next; 1735 } 1736 #endif 1737 if (inp->inp_flags & INP_RECVIF) { 1738 struct ifnet *ifp; 1739 struct sdlbuf { 1740 struct sockaddr_dl sdl; 1741 u_char pad[32]; 1742 } sdlbuf; 1743 struct sockaddr_dl *sdp; 1744 struct sockaddr_dl *sdl2 = &sdlbuf.sdl; 1745 1746 if ((ifp = m->m_pkthdr.rcvif) && 1747 ifp->if_index && ifp->if_index <= V_if_index) { 1748 sdp = (struct sockaddr_dl *)ifp->if_addr->ifa_addr; 1749 /* 1750 * Change our mind and don't try copy. 1751 */ 1752 if (sdp->sdl_family != AF_LINK || 1753 sdp->sdl_len > sizeof(sdlbuf)) { 1754 goto makedummy; 1755 } 1756 bcopy(sdp, sdl2, sdp->sdl_len); 1757 } else { 1758 makedummy: 1759 sdl2->sdl_len = 1760 offsetof(struct sockaddr_dl, sdl_data[0]); 1761 sdl2->sdl_family = AF_LINK; 1762 sdl2->sdl_index = 0; 1763 sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0; 1764 } 1765 *mp = sbcreatecontrol((caddr_t)sdl2, sdl2->sdl_len, 1766 IP_RECVIF, IPPROTO_IP); 1767 if (*mp) 1768 mp = &(*mp)->m_next; 1769 } 1770 if (inp->inp_flags & INP_RECVTOS) { 1771 *mp = sbcreatecontrol((caddr_t)&ip->ip_tos, 1772 sizeof(u_char), IP_RECVTOS, IPPROTO_IP); 1773 if (*mp) 1774 mp = &(*mp)->m_next; 1775 } 1776 1777 if (inp->inp_flags2 & INP_RECVFLOWID) { 1778 uint32_t flowid, flow_type; 1779 1780 flowid = m->m_pkthdr.flowid; 1781 flow_type = M_HASHTYPE_GET(m); 1782 1783 /* 1784 * XXX should handle the failure of one or the 1785 * other - don't populate both? 1786 */ 1787 *mp = sbcreatecontrol((caddr_t) &flowid, 1788 sizeof(uint32_t), IP_FLOWID, IPPROTO_IP); 1789 if (*mp) 1790 mp = &(*mp)->m_next; 1791 *mp = sbcreatecontrol((caddr_t) &flow_type, 1792 sizeof(uint32_t), IP_FLOWTYPE, IPPROTO_IP); 1793 if (*mp) 1794 mp = &(*mp)->m_next; 1795 } 1796 1797 #ifdef RSS 1798 if (inp->inp_flags2 & INP_RECVRSSBUCKETID) { 1799 uint32_t flowid, flow_type; 1800 uint32_t rss_bucketid; 1801 1802 flowid = m->m_pkthdr.flowid; 1803 flow_type = M_HASHTYPE_GET(m); 1804 1805 if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) { 1806 *mp = sbcreatecontrol((caddr_t) &rss_bucketid, 1807 sizeof(uint32_t), IP_RSSBUCKETID, IPPROTO_IP); 1808 if (*mp) 1809 mp = &(*mp)->m_next; 1810 } 1811 } 1812 #endif 1813 } 1814 1815 /* 1816 * XXXRW: Multicast routing code in ip_mroute.c is generally MPSAFE, but the 1817 * ip_rsvp and ip_rsvp_on variables need to be interlocked with rsvp_on 1818 * locking. This code remains in ip_input.c as ip_mroute.c is optionally 1819 * compiled. 1820 */ 1821 static VNET_DEFINE(int, ip_rsvp_on); 1822 VNET_DEFINE(struct socket *, ip_rsvpd); 1823 1824 #define V_ip_rsvp_on VNET(ip_rsvp_on) 1825 1826 int 1827 ip_rsvp_init(struct socket *so) 1828 { 1829 1830 if (so->so_type != SOCK_RAW || 1831 so->so_proto->pr_protocol != IPPROTO_RSVP) 1832 return EOPNOTSUPP; 1833 1834 if (V_ip_rsvpd != NULL) 1835 return EADDRINUSE; 1836 1837 V_ip_rsvpd = so; 1838 /* 1839 * This may seem silly, but we need to be sure we don't over-increment 1840 * the RSVP counter, in case something slips up. 1841 */ 1842 if (!V_ip_rsvp_on) { 1843 V_ip_rsvp_on = 1; 1844 V_rsvp_on++; 1845 } 1846 1847 return 0; 1848 } 1849 1850 int 1851 ip_rsvp_done(void) 1852 { 1853 1854 V_ip_rsvpd = NULL; 1855 /* 1856 * This may seem silly, but we need to be sure we don't over-decrement 1857 * the RSVP counter, in case something slips up. 1858 */ 1859 if (V_ip_rsvp_on) { 1860 V_ip_rsvp_on = 0; 1861 V_rsvp_on--; 1862 } 1863 return 0; 1864 } 1865 1866 int 1867 rsvp_input(struct mbuf **mp, int *offp, int proto) 1868 { 1869 struct mbuf *m; 1870 1871 m = *mp; 1872 *mp = NULL; 1873 1874 if (rsvp_input_p) { /* call the real one if loaded */ 1875 *mp = m; 1876 rsvp_input_p(mp, offp, proto); 1877 return (IPPROTO_DONE); 1878 } 1879 1880 /* Can still get packets with rsvp_on = 0 if there is a local member 1881 * of the group to which the RSVP packet is addressed. But in this 1882 * case we want to throw the packet away. 1883 */ 1884 1885 if (!V_rsvp_on) { 1886 m_freem(m); 1887 return (IPPROTO_DONE); 1888 } 1889 1890 if (V_ip_rsvpd != NULL) { 1891 *mp = m; 1892 rip_input(mp, offp, proto); 1893 return (IPPROTO_DONE); 1894 } 1895 /* Drop the packet */ 1896 m_freem(m); 1897 return (IPPROTO_DONE); 1898 } 1899