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_mac.h" 40 #include "opt_carp.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/callout.h> 45 #include <sys/mbuf.h> 46 #include <sys/malloc.h> 47 #include <sys/domain.h> 48 #include <sys/protosw.h> 49 #include <sys/socket.h> 50 #include <sys/time.h> 51 #include <sys/kernel.h> 52 #include <sys/syslog.h> 53 #include <sys/sysctl.h> 54 55 #include <net/pfil.h> 56 #include <net/if.h> 57 #include <net/if_types.h> 58 #include <net/if_var.h> 59 #include <net/if_dl.h> 60 #include <net/route.h> 61 #include <net/netisr.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_systm.h> 65 #include <netinet/in_var.h> 66 #include <netinet/ip.h> 67 #include <netinet/in_pcb.h> 68 #include <netinet/ip_var.h> 69 #include <netinet/ip_icmp.h> 70 #include <netinet/ip_options.h> 71 #include <machine/in_cksum.h> 72 #ifdef DEV_CARP 73 #include <netinet/ip_carp.h> 74 #endif 75 #ifdef IPSEC 76 #include <netinet/ip_ipsec.h> 77 #endif /* IPSEC */ 78 79 #include <sys/socketvar.h> 80 81 /* XXX: Temporary until ipfw_ether and ipfw_bridge are converted. */ 82 #include <netinet/ip_fw.h> 83 #include <netinet/ip_dummynet.h> 84 85 #include <security/mac/mac_framework.h> 86 87 int rsvp_on = 0; 88 89 int ipforwarding = 0; 90 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW, 91 &ipforwarding, 0, "Enable IP forwarding between interfaces"); 92 93 static int ipsendredirects = 1; /* XXX */ 94 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW, 95 &ipsendredirects, 0, "Enable sending IP redirects"); 96 97 int ip_defttl = IPDEFTTL; 98 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW, 99 &ip_defttl, 0, "Maximum TTL on IP packets"); 100 101 static int ip_keepfaith = 0; 102 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW, 103 &ip_keepfaith, 0, 104 "Enable packet capture for FAITH IPv4->IPv6 translater daemon"); 105 106 static int ip_sendsourcequench = 0; 107 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW, 108 &ip_sendsourcequench, 0, 109 "Enable the transmission of source quench packets"); 110 111 int ip_do_randomid = 0; 112 SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW, 113 &ip_do_randomid, 0, 114 "Assign random ip_id values"); 115 116 /* 117 * XXX - Setting ip_checkinterface mostly implements the receive side of 118 * the Strong ES model described in RFC 1122, but since the routing table 119 * and transmit implementation do not implement the Strong ES model, 120 * setting this to 1 results in an odd hybrid. 121 * 122 * XXX - ip_checkinterface currently must be disabled if you use ipnat 123 * to translate the destination address to another local interface. 124 * 125 * XXX - ip_checkinterface must be disabled if you add IP aliases 126 * to the loopback interface instead of the interface where the 127 * packets for those addresses are received. 128 */ 129 static int ip_checkinterface = 0; 130 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW, 131 &ip_checkinterface, 0, "Verify packet arrives on correct interface"); 132 133 struct pfil_head inet_pfil_hook; /* Packet filter hooks */ 134 135 static struct ifqueue ipintrq; 136 static int ipqmaxlen = IFQ_MAXLEN; 137 138 extern struct domain inetdomain; 139 extern struct protosw inetsw[]; 140 u_char ip_protox[IPPROTO_MAX]; 141 struct in_ifaddrhead in_ifaddrhead; /* first inet address */ 142 struct in_ifaddrhashhead *in_ifaddrhashtbl; /* inet addr hash table */ 143 u_long in_ifaddrhmask; /* mask for hash table */ 144 145 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW, 146 &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue"); 147 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD, 148 &ipintrq.ifq_drops, 0, 149 "Number of packets dropped from the IP input queue"); 150 151 struct ipstat ipstat; 152 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW, 153 &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)"); 154 155 /* 156 * IP datagram reassembly. 157 */ 158 #define IPREASS_NHASH_LOG2 6 159 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2) 160 #define IPREASS_HMASK (IPREASS_NHASH - 1) 161 #define IPREASS_HASH(x,y) \ 162 (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK) 163 164 static uma_zone_t ipq_zone; 165 static TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH]; 166 static struct mtx ipqlock; 167 168 #define IPQ_LOCK() mtx_lock(&ipqlock) 169 #define IPQ_UNLOCK() mtx_unlock(&ipqlock) 170 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF) 171 #define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED) 172 173 static void maxnipq_update(void); 174 static void ipq_zone_change(void *); 175 176 static int maxnipq; /* Administrative limit on # reass queues. */ 177 static int nipq = 0; /* Total # of reass queues */ 178 SYSCTL_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_RD, 179 &nipq, 0, "Current number of IPv4 fragment reassembly queue entries"); 180 181 static int maxfragsperpacket; 182 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW, 183 &maxfragsperpacket, 0, 184 "Maximum number of IPv4 fragments allowed per packet"); 185 186 struct callout ipport_tick_callout; 187 188 #ifdef IPCTL_DEFMTU 189 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, 190 &ip_mtu, 0, "Default MTU"); 191 #endif 192 193 #ifdef IPSTEALTH 194 int ipstealth = 0; 195 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW, 196 &ipstealth, 0, "IP stealth mode, no TTL decrementation on forwarding"); 197 #endif 198 199 /* 200 * ipfw_ether and ipfw_bridge hooks. 201 * XXX: Temporary until those are converted to pfil_hooks as well. 202 */ 203 ip_fw_chk_t *ip_fw_chk_ptr = NULL; 204 ip_dn_io_t *ip_dn_io_ptr = NULL; 205 int fw_one_pass = 1; 206 207 static void ip_freef(struct ipqhead *, struct ipq *); 208 209 /* 210 * IP initialization: fill in IP protocol switch table. 211 * All protocols not implemented in kernel go to raw IP protocol handler. 212 */ 213 void 214 ip_init(void) 215 { 216 struct protosw *pr; 217 int i; 218 219 TAILQ_INIT(&in_ifaddrhead); 220 in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask); 221 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 222 if (pr == NULL) 223 panic("ip_init: PF_INET not found"); 224 225 /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */ 226 for (i = 0; i < IPPROTO_MAX; i++) 227 ip_protox[i] = pr - inetsw; 228 /* 229 * Cycle through IP protocols and put them into the appropriate place 230 * in ip_protox[]. 231 */ 232 for (pr = inetdomain.dom_protosw; 233 pr < inetdomain.dom_protoswNPROTOSW; pr++) 234 if (pr->pr_domain->dom_family == PF_INET && 235 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) { 236 /* Be careful to only index valid IP protocols. */ 237 if (pr->pr_protocol < IPPROTO_MAX) 238 ip_protox[pr->pr_protocol] = pr - inetsw; 239 } 240 241 /* Initialize packet filter hooks. */ 242 inet_pfil_hook.ph_type = PFIL_TYPE_AF; 243 inet_pfil_hook.ph_af = AF_INET; 244 if ((i = pfil_head_register(&inet_pfil_hook)) != 0) 245 printf("%s: WARNING: unable to register pfil hook, " 246 "error %d\n", __func__, i); 247 248 /* Initialize IP reassembly queue. */ 249 IPQ_LOCK_INIT(); 250 for (i = 0; i < IPREASS_NHASH; i++) 251 TAILQ_INIT(&ipq[i]); 252 maxnipq = nmbclusters / 32; 253 maxfragsperpacket = 16; 254 ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL, 255 NULL, UMA_ALIGN_PTR, 0); 256 maxnipq_update(); 257 258 /* Start ipport_tick. */ 259 callout_init(&ipport_tick_callout, CALLOUT_MPSAFE); 260 ipport_tick(NULL); 261 EVENTHANDLER_REGISTER(shutdown_pre_sync, ip_fini, NULL, 262 SHUTDOWN_PRI_DEFAULT); 263 EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change, 264 NULL, EVENTHANDLER_PRI_ANY); 265 266 /* Initialize various other remaining things. */ 267 ip_id = time_second & 0xffff; 268 ipintrq.ifq_maxlen = ipqmaxlen; 269 mtx_init(&ipintrq.ifq_mtx, "ip_inq", NULL, MTX_DEF); 270 netisr_register(NETISR_IP, ip_input, &ipintrq, NETISR_MPSAFE); 271 } 272 273 void 274 ip_fini(void *xtp) 275 { 276 277 callout_stop(&ipport_tick_callout); 278 } 279 280 /* 281 * Ip input routine. Checksum and byte swap header. If fragmented 282 * try to reassemble. Process options. Pass to next level. 283 */ 284 void 285 ip_input(struct mbuf *m) 286 { 287 struct ip *ip = NULL; 288 struct in_ifaddr *ia = NULL; 289 struct ifaddr *ifa; 290 int checkif, hlen = 0; 291 u_short sum; 292 int dchg = 0; /* dest changed after fw */ 293 struct in_addr odst; /* original dst address */ 294 295 M_ASSERTPKTHDR(m); 296 297 if (m->m_flags & M_FASTFWD_OURS) { 298 /* 299 * Firewall or NAT changed destination to local. 300 * We expect ip_len and ip_off to be in host byte order. 301 */ 302 m->m_flags &= ~M_FASTFWD_OURS; 303 /* Set up some basics that will be used later. */ 304 ip = mtod(m, struct ip *); 305 hlen = ip->ip_hl << 2; 306 goto ours; 307 } 308 309 ipstat.ips_total++; 310 311 if (m->m_pkthdr.len < sizeof(struct ip)) 312 goto tooshort; 313 314 if (m->m_len < sizeof (struct ip) && 315 (m = m_pullup(m, sizeof (struct ip))) == NULL) { 316 ipstat.ips_toosmall++; 317 return; 318 } 319 ip = mtod(m, struct ip *); 320 321 if (ip->ip_v != IPVERSION) { 322 ipstat.ips_badvers++; 323 goto bad; 324 } 325 326 hlen = ip->ip_hl << 2; 327 if (hlen < sizeof(struct ip)) { /* minimum header length */ 328 ipstat.ips_badhlen++; 329 goto bad; 330 } 331 if (hlen > m->m_len) { 332 if ((m = m_pullup(m, hlen)) == NULL) { 333 ipstat.ips_badhlen++; 334 return; 335 } 336 ip = mtod(m, struct ip *); 337 } 338 339 /* 127/8 must not appear on wire - RFC1122 */ 340 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 341 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 342 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) { 343 ipstat.ips_badaddr++; 344 goto bad; 345 } 346 } 347 348 if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) { 349 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 350 } else { 351 if (hlen == sizeof(struct ip)) { 352 sum = in_cksum_hdr(ip); 353 } else { 354 sum = in_cksum(m, hlen); 355 } 356 } 357 if (sum) { 358 ipstat.ips_badsum++; 359 goto bad; 360 } 361 362 #ifdef ALTQ 363 if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 364 /* packet is dropped by traffic conditioner */ 365 return; 366 #endif 367 368 /* 369 * Convert fields to host representation. 370 */ 371 ip->ip_len = ntohs(ip->ip_len); 372 if (ip->ip_len < hlen) { 373 ipstat.ips_badlen++; 374 goto bad; 375 } 376 ip->ip_off = ntohs(ip->ip_off); 377 378 /* 379 * Check that the amount of data in the buffers 380 * is as at least much as the IP header would have us expect. 381 * Trim mbufs if longer than we expect. 382 * Drop packet if shorter than we expect. 383 */ 384 if (m->m_pkthdr.len < ip->ip_len) { 385 tooshort: 386 ipstat.ips_tooshort++; 387 goto bad; 388 } 389 if (m->m_pkthdr.len > ip->ip_len) { 390 if (m->m_len == m->m_pkthdr.len) { 391 m->m_len = ip->ip_len; 392 m->m_pkthdr.len = ip->ip_len; 393 } else 394 m_adj(m, ip->ip_len - m->m_pkthdr.len); 395 } 396 #ifdef IPSEC 397 /* 398 * Bypass packet filtering for packets from a tunnel (gif). 399 */ 400 if (ip_ipsec_filtertunnel(m)) 401 goto passin; 402 #endif /* IPSEC */ 403 404 /* 405 * Run through list of hooks for input packets. 406 * 407 * NB: Beware of the destination address changing (e.g. 408 * by NAT rewriting). When this happens, tell 409 * ip_forward to do the right thing. 410 */ 411 412 /* Jump over all PFIL processing if hooks are not active. */ 413 if (!PFIL_HOOKED(&inet_pfil_hook)) 414 goto passin; 415 416 odst = ip->ip_dst; 417 if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, 418 PFIL_IN, NULL) != 0) 419 return; 420 if (m == NULL) /* consumed by filter */ 421 return; 422 423 ip = mtod(m, struct ip *); 424 dchg = (odst.s_addr != ip->ip_dst.s_addr); 425 426 #ifdef IPFIREWALL_FORWARD 427 if (m->m_flags & M_FASTFWD_OURS) { 428 m->m_flags &= ~M_FASTFWD_OURS; 429 goto ours; 430 } 431 if ((dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL)) != 0) { 432 /* 433 * Directly ship on the packet. This allows to forward packets 434 * that were destined for us to some other directly connected 435 * host. 436 */ 437 ip_forward(m, dchg); 438 return; 439 } 440 #endif /* IPFIREWALL_FORWARD */ 441 442 passin: 443 /* 444 * Process options and, if not destined for us, 445 * ship it on. ip_dooptions returns 1 when an 446 * error was detected (causing an icmp message 447 * to be sent and the original packet to be freed). 448 */ 449 if (hlen > sizeof (struct ip) && ip_dooptions(m, 0)) 450 return; 451 452 /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no 453 * matter if it is destined to another node, or whether it is 454 * a multicast one, RSVP wants it! and prevents it from being forwarded 455 * anywhere else. Also checks if the rsvp daemon is running before 456 * grabbing the packet. 457 */ 458 if (rsvp_on && ip->ip_p==IPPROTO_RSVP) 459 goto ours; 460 461 /* 462 * Check our list of addresses, to see if the packet is for us. 463 * If we don't have any addresses, assume any unicast packet 464 * we receive might be for us (and let the upper layers deal 465 * with it). 466 */ 467 if (TAILQ_EMPTY(&in_ifaddrhead) && 468 (m->m_flags & (M_MCAST|M_BCAST)) == 0) 469 goto ours; 470 471 /* 472 * Enable a consistency check between the destination address 473 * and the arrival interface for a unicast packet (the RFC 1122 474 * strong ES model) if IP forwarding is disabled and the packet 475 * is not locally generated and the packet is not subject to 476 * 'ipfw fwd'. 477 * 478 * XXX - Checking also should be disabled if the destination 479 * address is ipnat'ed to a different interface. 480 * 481 * XXX - Checking is incompatible with IP aliases added 482 * to the loopback interface instead of the interface where 483 * the packets are received. 484 * 485 * XXX - This is the case for carp vhost IPs as well so we 486 * insert a workaround. If the packet got here, we already 487 * checked with carp_iamatch() and carp_forus(). 488 */ 489 checkif = ip_checkinterface && (ipforwarding == 0) && 490 m->m_pkthdr.rcvif != NULL && 491 ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) && 492 #ifdef DEV_CARP 493 !m->m_pkthdr.rcvif->if_carp && 494 #endif 495 (dchg == 0); 496 497 /* 498 * Check for exact addresses in the hash bucket. 499 */ 500 LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) { 501 /* 502 * If the address matches, verify that the packet 503 * arrived via the correct interface if checking is 504 * enabled. 505 */ 506 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr && 507 (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif)) 508 goto ours; 509 } 510 /* 511 * Check for broadcast addresses. 512 * 513 * Only accept broadcast packets that arrive via the matching 514 * interface. Reception of forwarded directed broadcasts would 515 * be handled via ip_forward() and ether_output() with the loopback 516 * into the stack for SIMPLEX interfaces handled by ether_output(). 517 */ 518 if (m->m_pkthdr.rcvif != NULL && 519 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 520 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 521 if (ifa->ifa_addr->sa_family != AF_INET) 522 continue; 523 ia = ifatoia(ifa); 524 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 525 ip->ip_dst.s_addr) 526 goto ours; 527 if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr) 528 goto ours; 529 #ifdef BOOTP_COMPAT 530 if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) 531 goto ours; 532 #endif 533 } 534 } 535 /* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */ 536 if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) { 537 ipstat.ips_cantforward++; 538 m_freem(m); 539 return; 540 } 541 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 542 struct in_multi *inm; 543 if (ip_mrouter) { 544 /* 545 * If we are acting as a multicast router, all 546 * incoming multicast packets are passed to the 547 * kernel-level multicast forwarding function. 548 * The packet is returned (relatively) intact; if 549 * ip_mforward() returns a non-zero value, the packet 550 * must be discarded, else it may be accepted below. 551 */ 552 if (ip_mforward && 553 ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) { 554 ipstat.ips_cantforward++; 555 m_freem(m); 556 return; 557 } 558 559 /* 560 * The process-level routing daemon needs to receive 561 * all multicast IGMP packets, whether or not this 562 * host belongs to their destination groups. 563 */ 564 if (ip->ip_p == IPPROTO_IGMP) 565 goto ours; 566 ipstat.ips_forward++; 567 } 568 /* 569 * See if we belong to the destination multicast group on the 570 * arrival interface. 571 */ 572 IN_MULTI_LOCK(); 573 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 574 IN_MULTI_UNLOCK(); 575 if (inm == NULL) { 576 ipstat.ips_notmember++; 577 m_freem(m); 578 return; 579 } 580 goto ours; 581 } 582 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 583 goto ours; 584 if (ip->ip_dst.s_addr == INADDR_ANY) 585 goto ours; 586 587 /* 588 * FAITH(Firewall Aided Internet Translator) 589 */ 590 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 591 if (ip_keepfaith) { 592 if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP) 593 goto ours; 594 } 595 m_freem(m); 596 return; 597 } 598 599 /* 600 * Not for us; forward if possible and desirable. 601 */ 602 if (ipforwarding == 0) { 603 ipstat.ips_cantforward++; 604 m_freem(m); 605 } else { 606 #ifdef IPSEC 607 if (ip_ipsec_fwd(m)) 608 goto bad; 609 #endif /* IPSEC */ 610 ip_forward(m, dchg); 611 } 612 return; 613 614 ours: 615 #ifdef IPSTEALTH 616 /* 617 * IPSTEALTH: Process non-routing options only 618 * if the packet is destined for us. 619 */ 620 if (ipstealth && hlen > sizeof (struct ip) && 621 ip_dooptions(m, 1)) 622 return; 623 #endif /* IPSTEALTH */ 624 625 /* Count the packet in the ip address stats */ 626 if (ia != NULL) { 627 ia->ia_ifa.if_ipackets++; 628 ia->ia_ifa.if_ibytes += m->m_pkthdr.len; 629 } 630 631 /* 632 * Attempt reassembly; if it succeeds, proceed. 633 * ip_reass() will return a different mbuf. 634 */ 635 if (ip->ip_off & (IP_MF | IP_OFFMASK)) { 636 m = ip_reass(m); 637 if (m == NULL) 638 return; 639 ip = mtod(m, struct ip *); 640 /* Get the header length of the reassembled packet */ 641 hlen = ip->ip_hl << 2; 642 } 643 644 /* 645 * Further protocols expect the packet length to be w/o the 646 * IP header. 647 */ 648 ip->ip_len -= hlen; 649 650 #ifdef IPSEC 651 /* 652 * enforce IPsec policy checking if we are seeing last header. 653 * note that we do not visit this with protocols with pcb layer 654 * code - like udp/tcp/raw ip. 655 */ 656 if (ip_ipsec_input(m)) 657 goto bad; 658 #endif /* IPSEC */ 659 660 /* 661 * Switch out to protocol's input routine. 662 */ 663 ipstat.ips_delivered++; 664 665 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 666 return; 667 bad: 668 m_freem(m); 669 } 670 671 /* 672 * After maxnipq has been updated, propagate the change to UMA. The UMA zone 673 * max has slightly different semantics than the sysctl, for historical 674 * reasons. 675 */ 676 static void 677 maxnipq_update(void) 678 { 679 680 /* 681 * -1 for unlimited allocation. 682 */ 683 if (maxnipq < 0) 684 uma_zone_set_max(ipq_zone, 0); 685 /* 686 * Positive number for specific bound. 687 */ 688 if (maxnipq > 0) 689 uma_zone_set_max(ipq_zone, maxnipq); 690 /* 691 * Zero specifies no further fragment queue allocation -- set the 692 * bound very low, but rely on implementation elsewhere to actually 693 * prevent allocation and reclaim current queues. 694 */ 695 if (maxnipq == 0) 696 uma_zone_set_max(ipq_zone, 1); 697 } 698 699 static void 700 ipq_zone_change(void *tag) 701 { 702 703 if (maxnipq > 0 && maxnipq < (nmbclusters / 32)) { 704 maxnipq = nmbclusters / 32; 705 maxnipq_update(); 706 } 707 } 708 709 static int 710 sysctl_maxnipq(SYSCTL_HANDLER_ARGS) 711 { 712 int error, i; 713 714 i = maxnipq; 715 error = sysctl_handle_int(oidp, &i, 0, req); 716 if (error || !req->newptr) 717 return (error); 718 719 /* 720 * XXXRW: Might be a good idea to sanity check the argument and place 721 * an extreme upper bound. 722 */ 723 if (i < -1) 724 return (EINVAL); 725 maxnipq = i; 726 maxnipq_update(); 727 return (0); 728 } 729 730 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW, 731 NULL, 0, sysctl_maxnipq, "I", 732 "Maximum number of IPv4 fragment reassembly queue entries"); 733 734 /* 735 * Take incoming datagram fragment and try to reassemble it into 736 * whole datagram. If the argument is the first fragment or one 737 * in between the function will return NULL and store the mbuf 738 * in the fragment chain. If the argument is the last fragment 739 * the packet will be reassembled and the pointer to the new 740 * mbuf returned for further processing. Only m_tags attached 741 * to the first packet/fragment are preserved. 742 * The IP header is *NOT* adjusted out of iplen. 743 */ 744 struct mbuf * 745 ip_reass(struct mbuf *m) 746 { 747 struct ip *ip; 748 struct mbuf *p, *q, *nq, *t; 749 struct ipq *fp = NULL; 750 struct ipqhead *head; 751 int i, hlen, next; 752 u_int8_t ecn, ecn0; 753 u_short hash; 754 755 /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */ 756 if (maxnipq == 0 || maxfragsperpacket == 0) { 757 ipstat.ips_fragments++; 758 ipstat.ips_fragdropped++; 759 m_freem(m); 760 return (NULL); 761 } 762 763 ip = mtod(m, struct ip *); 764 hlen = ip->ip_hl << 2; 765 766 hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); 767 head = &ipq[hash]; 768 IPQ_LOCK(); 769 770 /* 771 * Look for queue of fragments 772 * of this datagram. 773 */ 774 TAILQ_FOREACH(fp, head, ipq_list) 775 if (ip->ip_id == fp->ipq_id && 776 ip->ip_src.s_addr == fp->ipq_src.s_addr && 777 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 778 #ifdef MAC 779 mac_ipq_match(m, fp) && 780 #endif 781 ip->ip_p == fp->ipq_p) 782 goto found; 783 784 fp = NULL; 785 786 /* 787 * Attempt to trim the number of allocated fragment queues if it 788 * exceeds the administrative limit. 789 */ 790 if ((nipq > maxnipq) && (maxnipq > 0)) { 791 /* 792 * drop something from the tail of the current queue 793 * before proceeding further 794 */ 795 struct ipq *q = TAILQ_LAST(head, ipqhead); 796 if (q == NULL) { /* gak */ 797 for (i = 0; i < IPREASS_NHASH; i++) { 798 struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead); 799 if (r) { 800 ipstat.ips_fragtimeout += r->ipq_nfrags; 801 ip_freef(&ipq[i], r); 802 break; 803 } 804 } 805 } else { 806 ipstat.ips_fragtimeout += q->ipq_nfrags; 807 ip_freef(head, q); 808 } 809 } 810 811 found: 812 /* 813 * Adjust ip_len to not reflect header, 814 * convert offset of this to bytes. 815 */ 816 ip->ip_len -= hlen; 817 if (ip->ip_off & IP_MF) { 818 /* 819 * Make sure that fragments have a data length 820 * that's a non-zero multiple of 8 bytes. 821 */ 822 if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) { 823 ipstat.ips_toosmall++; /* XXX */ 824 goto dropfrag; 825 } 826 m->m_flags |= M_FRAG; 827 } else 828 m->m_flags &= ~M_FRAG; 829 ip->ip_off <<= 3; 830 831 832 /* 833 * Attempt reassembly; if it succeeds, proceed. 834 * ip_reass() will return a different mbuf. 835 */ 836 ipstat.ips_fragments++; 837 m->m_pkthdr.header = ip; 838 839 /* Previous ip_reass() started here. */ 840 /* 841 * Presence of header sizes in mbufs 842 * would confuse code below. 843 */ 844 m->m_data += hlen; 845 m->m_len -= hlen; 846 847 /* 848 * If first fragment to arrive, create a reassembly queue. 849 */ 850 if (fp == NULL) { 851 fp = uma_zalloc(ipq_zone, M_NOWAIT); 852 if (fp == NULL) 853 goto dropfrag; 854 #ifdef MAC 855 if (mac_ipq_init(fp, M_NOWAIT) != 0) { 856 uma_zfree(ipq_zone, fp); 857 fp = NULL; 858 goto dropfrag; 859 } 860 mac_ipq_create(m, fp); 861 #endif 862 TAILQ_INSERT_HEAD(head, fp, ipq_list); 863 nipq++; 864 fp->ipq_nfrags = 1; 865 fp->ipq_ttl = IPFRAGTTL; 866 fp->ipq_p = ip->ip_p; 867 fp->ipq_id = ip->ip_id; 868 fp->ipq_src = ip->ip_src; 869 fp->ipq_dst = ip->ip_dst; 870 fp->ipq_frags = m; 871 m->m_nextpkt = NULL; 872 goto done; 873 } else { 874 fp->ipq_nfrags++; 875 #ifdef MAC 876 mac_ipq_update(m, fp); 877 #endif 878 } 879 880 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.header)) 881 882 /* 883 * Handle ECN by comparing this segment with the first one; 884 * if CE is set, do not lose CE. 885 * drop if CE and not-ECT are mixed for the same packet. 886 */ 887 ecn = ip->ip_tos & IPTOS_ECN_MASK; 888 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; 889 if (ecn == IPTOS_ECN_CE) { 890 if (ecn0 == IPTOS_ECN_NOTECT) 891 goto dropfrag; 892 if (ecn0 != IPTOS_ECN_CE) 893 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE; 894 } 895 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) 896 goto dropfrag; 897 898 /* 899 * Find a segment which begins after this one does. 900 */ 901 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) 902 if (GETIP(q)->ip_off > ip->ip_off) 903 break; 904 905 /* 906 * If there is a preceding segment, it may provide some of 907 * our data already. If so, drop the data from the incoming 908 * segment. If it provides all of our data, drop us, otherwise 909 * stick new segment in the proper place. 910 * 911 * If some of the data is dropped from the the preceding 912 * segment, then it's checksum is invalidated. 913 */ 914 if (p) { 915 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off; 916 if (i > 0) { 917 if (i >= ip->ip_len) 918 goto dropfrag; 919 m_adj(m, i); 920 m->m_pkthdr.csum_flags = 0; 921 ip->ip_off += i; 922 ip->ip_len -= i; 923 } 924 m->m_nextpkt = p->m_nextpkt; 925 p->m_nextpkt = m; 926 } else { 927 m->m_nextpkt = fp->ipq_frags; 928 fp->ipq_frags = m; 929 } 930 931 /* 932 * While we overlap succeeding segments trim them or, 933 * if they are completely covered, dequeue them. 934 */ 935 for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off; 936 q = nq) { 937 i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off; 938 if (i < GETIP(q)->ip_len) { 939 GETIP(q)->ip_len -= i; 940 GETIP(q)->ip_off += i; 941 m_adj(q, i); 942 q->m_pkthdr.csum_flags = 0; 943 break; 944 } 945 nq = q->m_nextpkt; 946 m->m_nextpkt = nq; 947 ipstat.ips_fragdropped++; 948 fp->ipq_nfrags--; 949 m_freem(q); 950 } 951 952 /* 953 * Check for complete reassembly and perform frag per packet 954 * limiting. 955 * 956 * Frag limiting is performed here so that the nth frag has 957 * a chance to complete the packet before we drop the packet. 958 * As a result, n+1 frags are actually allowed per packet, but 959 * only n will ever be stored. (n = maxfragsperpacket.) 960 * 961 */ 962 next = 0; 963 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { 964 if (GETIP(q)->ip_off != next) { 965 if (fp->ipq_nfrags > maxfragsperpacket) { 966 ipstat.ips_fragdropped += fp->ipq_nfrags; 967 ip_freef(head, fp); 968 } 969 goto done; 970 } 971 next += GETIP(q)->ip_len; 972 } 973 /* Make sure the last packet didn't have the IP_MF flag */ 974 if (p->m_flags & M_FRAG) { 975 if (fp->ipq_nfrags > maxfragsperpacket) { 976 ipstat.ips_fragdropped += fp->ipq_nfrags; 977 ip_freef(head, fp); 978 } 979 goto done; 980 } 981 982 /* 983 * Reassembly is complete. Make sure the packet is a sane size. 984 */ 985 q = fp->ipq_frags; 986 ip = GETIP(q); 987 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { 988 ipstat.ips_toolong++; 989 ipstat.ips_fragdropped += fp->ipq_nfrags; 990 ip_freef(head, fp); 991 goto done; 992 } 993 994 /* 995 * Concatenate fragments. 996 */ 997 m = q; 998 t = m->m_next; 999 m->m_next = NULL; 1000 m_cat(m, t); 1001 nq = q->m_nextpkt; 1002 q->m_nextpkt = NULL; 1003 for (q = nq; q != NULL; q = nq) { 1004 nq = q->m_nextpkt; 1005 q->m_nextpkt = NULL; 1006 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; 1007 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; 1008 m_cat(m, q); 1009 } 1010 /* 1011 * In order to do checksumming faster we do 'end-around carry' here 1012 * (and not in for{} loop), though it implies we are not going to 1013 * reassemble more than 64k fragments. 1014 */ 1015 m->m_pkthdr.csum_data = 1016 (m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16); 1017 #ifdef MAC 1018 mac_ipq_reassemble(fp, m); 1019 mac_ipq_destroy(fp); 1020 #endif 1021 1022 /* 1023 * Create header for new ip packet by modifying header of first 1024 * packet; dequeue and discard fragment reassembly header. 1025 * Make header visible. 1026 */ 1027 ip->ip_len = (ip->ip_hl << 2) + next; 1028 ip->ip_src = fp->ipq_src; 1029 ip->ip_dst = fp->ipq_dst; 1030 TAILQ_REMOVE(head, fp, ipq_list); 1031 nipq--; 1032 uma_zfree(ipq_zone, fp); 1033 m->m_len += (ip->ip_hl << 2); 1034 m->m_data -= (ip->ip_hl << 2); 1035 /* some debugging cruft by sklower, below, will go away soon */ 1036 if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */ 1037 m_fixhdr(m); 1038 ipstat.ips_reassembled++; 1039 IPQ_UNLOCK(); 1040 return (m); 1041 1042 dropfrag: 1043 ipstat.ips_fragdropped++; 1044 if (fp != NULL) 1045 fp->ipq_nfrags--; 1046 m_freem(m); 1047 done: 1048 IPQ_UNLOCK(); 1049 return (NULL); 1050 1051 #undef GETIP 1052 } 1053 1054 /* 1055 * Free a fragment reassembly header and all 1056 * associated datagrams. 1057 */ 1058 static void 1059 ip_freef(struct ipqhead *fhp, struct ipq *fp) 1060 { 1061 struct mbuf *q; 1062 1063 IPQ_LOCK_ASSERT(); 1064 1065 while (fp->ipq_frags) { 1066 q = fp->ipq_frags; 1067 fp->ipq_frags = q->m_nextpkt; 1068 m_freem(q); 1069 } 1070 TAILQ_REMOVE(fhp, fp, ipq_list); 1071 uma_zfree(ipq_zone, fp); 1072 nipq--; 1073 } 1074 1075 /* 1076 * IP timer processing; 1077 * if a timer expires on a reassembly 1078 * queue, discard it. 1079 */ 1080 void 1081 ip_slowtimo(void) 1082 { 1083 struct ipq *fp; 1084 int i; 1085 1086 IPQ_LOCK(); 1087 for (i = 0; i < IPREASS_NHASH; i++) { 1088 for(fp = TAILQ_FIRST(&ipq[i]); fp;) { 1089 struct ipq *fpp; 1090 1091 fpp = fp; 1092 fp = TAILQ_NEXT(fp, ipq_list); 1093 if(--fpp->ipq_ttl == 0) { 1094 ipstat.ips_fragtimeout += fpp->ipq_nfrags; 1095 ip_freef(&ipq[i], fpp); 1096 } 1097 } 1098 } 1099 /* 1100 * If we are over the maximum number of fragments 1101 * (due to the limit being lowered), drain off 1102 * enough to get down to the new limit. 1103 */ 1104 if (maxnipq >= 0 && nipq > maxnipq) { 1105 for (i = 0; i < IPREASS_NHASH; i++) { 1106 while (nipq > maxnipq && !TAILQ_EMPTY(&ipq[i])) { 1107 ipstat.ips_fragdropped += 1108 TAILQ_FIRST(&ipq[i])->ipq_nfrags; 1109 ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i])); 1110 } 1111 } 1112 } 1113 IPQ_UNLOCK(); 1114 } 1115 1116 /* 1117 * Drain off all datagram fragments. 1118 */ 1119 void 1120 ip_drain(void) 1121 { 1122 int i; 1123 1124 IPQ_LOCK(); 1125 for (i = 0; i < IPREASS_NHASH; i++) { 1126 while(!TAILQ_EMPTY(&ipq[i])) { 1127 ipstat.ips_fragdropped += 1128 TAILQ_FIRST(&ipq[i])->ipq_nfrags; 1129 ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i])); 1130 } 1131 } 1132 IPQ_UNLOCK(); 1133 in_rtqdrain(); 1134 } 1135 1136 /* 1137 * The protocol to be inserted into ip_protox[] must be already registered 1138 * in inetsw[], either statically or through pf_proto_register(). 1139 */ 1140 int 1141 ipproto_register(u_char ipproto) 1142 { 1143 struct protosw *pr; 1144 1145 /* Sanity checks. */ 1146 if (ipproto == 0) 1147 return (EPROTONOSUPPORT); 1148 1149 /* 1150 * The protocol slot must not be occupied by another protocol 1151 * already. An index pointing to IPPROTO_RAW is unused. 1152 */ 1153 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1154 if (pr == NULL) 1155 return (EPFNOSUPPORT); 1156 if (ip_protox[ipproto] != pr - inetsw) /* IPPROTO_RAW */ 1157 return (EEXIST); 1158 1159 /* Find the protocol position in inetsw[] and set the index. */ 1160 for (pr = inetdomain.dom_protosw; 1161 pr < inetdomain.dom_protoswNPROTOSW; pr++) { 1162 if (pr->pr_domain->dom_family == PF_INET && 1163 pr->pr_protocol && pr->pr_protocol == ipproto) { 1164 /* Be careful to only index valid IP protocols. */ 1165 if (pr->pr_protocol < IPPROTO_MAX) { 1166 ip_protox[pr->pr_protocol] = pr - inetsw; 1167 return (0); 1168 } else 1169 return (EINVAL); 1170 } 1171 } 1172 return (EPROTONOSUPPORT); 1173 } 1174 1175 int 1176 ipproto_unregister(u_char ipproto) 1177 { 1178 struct protosw *pr; 1179 1180 /* Sanity checks. */ 1181 if (ipproto == 0) 1182 return (EPROTONOSUPPORT); 1183 1184 /* Check if the protocol was indeed registered. */ 1185 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1186 if (pr == NULL) 1187 return (EPFNOSUPPORT); 1188 if (ip_protox[ipproto] == pr - inetsw) /* IPPROTO_RAW */ 1189 return (ENOENT); 1190 1191 /* Reset the protocol slot to IPPROTO_RAW. */ 1192 ip_protox[ipproto] = pr - inetsw; 1193 return (0); 1194 } 1195 1196 /* 1197 * Given address of next destination (final or next hop), 1198 * return internet address info of interface to be used to get there. 1199 */ 1200 struct in_ifaddr * 1201 ip_rtaddr(struct in_addr dst) 1202 { 1203 struct route sro; 1204 struct sockaddr_in *sin; 1205 struct in_ifaddr *ifa; 1206 1207 bzero(&sro, sizeof(sro)); 1208 sin = (struct sockaddr_in *)&sro.ro_dst; 1209 sin->sin_family = AF_INET; 1210 sin->sin_len = sizeof(*sin); 1211 sin->sin_addr = dst; 1212 rtalloc_ign(&sro, RTF_CLONING); 1213 1214 if (sro.ro_rt == NULL) 1215 return (NULL); 1216 1217 ifa = ifatoia(sro.ro_rt->rt_ifa); 1218 RTFREE(sro.ro_rt); 1219 return (ifa); 1220 } 1221 1222 u_char inetctlerrmap[PRC_NCMDS] = { 1223 0, 0, 0, 0, 1224 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 1225 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 1226 EMSGSIZE, EHOSTUNREACH, 0, 0, 1227 0, 0, EHOSTUNREACH, 0, 1228 ENOPROTOOPT, ECONNREFUSED 1229 }; 1230 1231 /* 1232 * Forward a packet. If some error occurs return the sender 1233 * an icmp packet. Note we can't always generate a meaningful 1234 * icmp message because icmp doesn't have a large enough repertoire 1235 * of codes and types. 1236 * 1237 * If not forwarding, just drop the packet. This could be confusing 1238 * if ipforwarding was zero but some routing protocol was advancing 1239 * us as a gateway to somewhere. However, we must let the routing 1240 * protocol deal with that. 1241 * 1242 * The srcrt parameter indicates whether the packet is being forwarded 1243 * via a source route. 1244 */ 1245 void 1246 ip_forward(struct mbuf *m, int srcrt) 1247 { 1248 struct ip *ip = mtod(m, struct ip *); 1249 struct in_ifaddr *ia = NULL; 1250 struct mbuf *mcopy; 1251 struct in_addr dest; 1252 struct route ro; 1253 int error, type = 0, code = 0, mtu = 0; 1254 1255 if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) { 1256 ipstat.ips_cantforward++; 1257 m_freem(m); 1258 return; 1259 } 1260 #ifdef IPSTEALTH 1261 if (!ipstealth) { 1262 #endif 1263 if (ip->ip_ttl <= IPTTLDEC) { 1264 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 1265 0, 0); 1266 return; 1267 } 1268 #ifdef IPSTEALTH 1269 } 1270 #endif 1271 1272 ia = ip_rtaddr(ip->ip_dst); 1273 if (!srcrt && ia == NULL) { 1274 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 1275 return; 1276 } 1277 1278 /* 1279 * Save the IP header and at most 8 bytes of the payload, 1280 * in case we need to generate an ICMP message to the src. 1281 * 1282 * XXX this can be optimized a lot by saving the data in a local 1283 * buffer on the stack (72 bytes at most), and only allocating the 1284 * mbuf if really necessary. The vast majority of the packets 1285 * are forwarded without having to send an ICMP back (either 1286 * because unnecessary, or because rate limited), so we are 1287 * really we are wasting a lot of work here. 1288 * 1289 * We don't use m_copy() because it might return a reference 1290 * to a shared cluster. Both this function and ip_output() 1291 * assume exclusive access to the IP header in `m', so any 1292 * data in a cluster may change before we reach icmp_error(). 1293 */ 1294 MGETHDR(mcopy, M_DONTWAIT, m->m_type); 1295 if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) { 1296 /* 1297 * It's probably ok if the pkthdr dup fails (because 1298 * the deep copy of the tag chain failed), but for now 1299 * be conservative and just discard the copy since 1300 * code below may some day want the tags. 1301 */ 1302 m_free(mcopy); 1303 mcopy = NULL; 1304 } 1305 if (mcopy != NULL) { 1306 mcopy->m_len = min(ip->ip_len, M_TRAILINGSPACE(mcopy)); 1307 mcopy->m_pkthdr.len = mcopy->m_len; 1308 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t)); 1309 } 1310 1311 #ifdef IPSTEALTH 1312 if (!ipstealth) { 1313 #endif 1314 ip->ip_ttl -= IPTTLDEC; 1315 #ifdef IPSTEALTH 1316 } 1317 #endif 1318 1319 /* 1320 * If forwarding packet using same interface that it came in on, 1321 * perhaps should send a redirect to sender to shortcut a hop. 1322 * Only send redirect if source is sending directly to us, 1323 * and if packet was not source routed (or has any options). 1324 * Also, don't send redirect if forwarding using a default route 1325 * or a route modified by a redirect. 1326 */ 1327 dest.s_addr = 0; 1328 if (!srcrt && ipsendredirects && ia->ia_ifp == m->m_pkthdr.rcvif) { 1329 struct sockaddr_in *sin; 1330 struct rtentry *rt; 1331 1332 bzero(&ro, sizeof(ro)); 1333 sin = (struct sockaddr_in *)&ro.ro_dst; 1334 sin->sin_family = AF_INET; 1335 sin->sin_len = sizeof(*sin); 1336 sin->sin_addr = ip->ip_dst; 1337 rtalloc_ign(&ro, RTF_CLONING); 1338 1339 rt = ro.ro_rt; 1340 1341 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1342 satosin(rt_key(rt))->sin_addr.s_addr != 0) { 1343 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1344 u_long src = ntohl(ip->ip_src.s_addr); 1345 1346 if (RTA(rt) && 1347 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1348 if (rt->rt_flags & RTF_GATEWAY) 1349 dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr; 1350 else 1351 dest.s_addr = ip->ip_dst.s_addr; 1352 /* Router requirements says to only send host redirects */ 1353 type = ICMP_REDIRECT; 1354 code = ICMP_REDIRECT_HOST; 1355 } 1356 } 1357 if (rt) 1358 RTFREE(rt); 1359 } 1360 1361 /* 1362 * Try to cache the route MTU from ip_output so we can consider it for 1363 * the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191. 1364 */ 1365 bzero(&ro, sizeof(ro)); 1366 rtalloc_ign(&ro, RTF_CLONING); 1367 1368 error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL); 1369 1370 if (error == EMSGSIZE && ro.ro_rt) 1371 mtu = ro.ro_rt->rt_rmx.rmx_mtu; 1372 if (ro.ro_rt) 1373 RTFREE(ro.ro_rt); 1374 1375 if (error) 1376 ipstat.ips_cantforward++; 1377 else { 1378 ipstat.ips_forward++; 1379 if (type) 1380 ipstat.ips_redirectsent++; 1381 else { 1382 if (mcopy) 1383 m_freem(mcopy); 1384 return; 1385 } 1386 } 1387 if (mcopy == NULL) 1388 return; 1389 1390 switch (error) { 1391 1392 case 0: /* forwarded, but need redirect */ 1393 /* type, code set above */ 1394 break; 1395 1396 case ENETUNREACH: /* shouldn't happen, checked above */ 1397 case EHOSTUNREACH: 1398 case ENETDOWN: 1399 case EHOSTDOWN: 1400 default: 1401 type = ICMP_UNREACH; 1402 code = ICMP_UNREACH_HOST; 1403 break; 1404 1405 case EMSGSIZE: 1406 type = ICMP_UNREACH; 1407 code = ICMP_UNREACH_NEEDFRAG; 1408 1409 #ifdef IPSEC 1410 /* 1411 * If IPsec is configured for this path, 1412 * override any possibly mtu value set by ip_output. 1413 */ 1414 mtu = ip_ipsec_mtu(m, mtu); 1415 #endif /* IPSEC */ 1416 /* 1417 * If the MTU was set before make sure we are below the 1418 * interface MTU. 1419 * If the MTU wasn't set before use the interface mtu or 1420 * fall back to the next smaller mtu step compared to the 1421 * current packet size. 1422 */ 1423 if (mtu != 0) { 1424 if (ia != NULL) 1425 mtu = min(mtu, ia->ia_ifp->if_mtu); 1426 } else { 1427 if (ia != NULL) 1428 mtu = ia->ia_ifp->if_mtu; 1429 else 1430 mtu = ip_next_mtu(ip->ip_len, 0); 1431 } 1432 ipstat.ips_cantfrag++; 1433 break; 1434 1435 case ENOBUFS: 1436 /* 1437 * A router should not generate ICMP_SOURCEQUENCH as 1438 * required in RFC1812 Requirements for IP Version 4 Routers. 1439 * Source quench could be a big problem under DoS attacks, 1440 * or if the underlying interface is rate-limited. 1441 * Those who need source quench packets may re-enable them 1442 * via the net.inet.ip.sendsourcequench sysctl. 1443 */ 1444 if (ip_sendsourcequench == 0) { 1445 m_freem(mcopy); 1446 return; 1447 } else { 1448 type = ICMP_SOURCEQUENCH; 1449 code = 0; 1450 } 1451 break; 1452 1453 case EACCES: /* ipfw denied packet */ 1454 m_freem(mcopy); 1455 return; 1456 } 1457 icmp_error(mcopy, type, code, dest.s_addr, mtu); 1458 } 1459 1460 void 1461 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip, 1462 struct mbuf *m) 1463 { 1464 if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) { 1465 struct bintime bt; 1466 1467 bintime(&bt); 1468 if (inp->inp_socket->so_options & SO_BINTIME) { 1469 *mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt), 1470 SCM_BINTIME, SOL_SOCKET); 1471 if (*mp) 1472 mp = &(*mp)->m_next; 1473 } 1474 if (inp->inp_socket->so_options & SO_TIMESTAMP) { 1475 struct timeval tv; 1476 1477 bintime2timeval(&bt, &tv); 1478 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv), 1479 SCM_TIMESTAMP, SOL_SOCKET); 1480 if (*mp) 1481 mp = &(*mp)->m_next; 1482 } 1483 } 1484 if (inp->inp_flags & INP_RECVDSTADDR) { 1485 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst, 1486 sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP); 1487 if (*mp) 1488 mp = &(*mp)->m_next; 1489 } 1490 if (inp->inp_flags & INP_RECVTTL) { 1491 *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl, 1492 sizeof(u_char), IP_RECVTTL, IPPROTO_IP); 1493 if (*mp) 1494 mp = &(*mp)->m_next; 1495 } 1496 #ifdef notyet 1497 /* XXX 1498 * Moving these out of udp_input() made them even more broken 1499 * than they already were. 1500 */ 1501 /* options were tossed already */ 1502 if (inp->inp_flags & INP_RECVOPTS) { 1503 *mp = sbcreatecontrol((caddr_t) opts_deleted_above, 1504 sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP); 1505 if (*mp) 1506 mp = &(*mp)->m_next; 1507 } 1508 /* ip_srcroute doesn't do what we want here, need to fix */ 1509 if (inp->inp_flags & INP_RECVRETOPTS) { 1510 *mp = sbcreatecontrol((caddr_t) ip_srcroute(m), 1511 sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP); 1512 if (*mp) 1513 mp = &(*mp)->m_next; 1514 } 1515 #endif 1516 if (inp->inp_flags & INP_RECVIF) { 1517 struct ifnet *ifp; 1518 struct sdlbuf { 1519 struct sockaddr_dl sdl; 1520 u_char pad[32]; 1521 } sdlbuf; 1522 struct sockaddr_dl *sdp; 1523 struct sockaddr_dl *sdl2 = &sdlbuf.sdl; 1524 1525 if (((ifp = m->m_pkthdr.rcvif)) 1526 && ( ifp->if_index && (ifp->if_index <= if_index))) { 1527 sdp = (struct sockaddr_dl *)ifp->if_addr->ifa_addr; 1528 /* 1529 * Change our mind and don't try copy. 1530 */ 1531 if ((sdp->sdl_family != AF_LINK) 1532 || (sdp->sdl_len > sizeof(sdlbuf))) { 1533 goto makedummy; 1534 } 1535 bcopy(sdp, sdl2, sdp->sdl_len); 1536 } else { 1537 makedummy: 1538 sdl2->sdl_len 1539 = offsetof(struct sockaddr_dl, sdl_data[0]); 1540 sdl2->sdl_family = AF_LINK; 1541 sdl2->sdl_index = 0; 1542 sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0; 1543 } 1544 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len, 1545 IP_RECVIF, IPPROTO_IP); 1546 if (*mp) 1547 mp = &(*mp)->m_next; 1548 } 1549 } 1550 1551 /* 1552 * XXXRW: Multicast routing code in ip_mroute.c is generally MPSAFE, but the 1553 * ip_rsvp and ip_rsvp_on variables need to be interlocked with rsvp_on 1554 * locking. This code remains in ip_input.c as ip_mroute.c is optionally 1555 * compiled. 1556 */ 1557 static int ip_rsvp_on; 1558 struct socket *ip_rsvpd; 1559 int 1560 ip_rsvp_init(struct socket *so) 1561 { 1562 if (so->so_type != SOCK_RAW || 1563 so->so_proto->pr_protocol != IPPROTO_RSVP) 1564 return EOPNOTSUPP; 1565 1566 if (ip_rsvpd != NULL) 1567 return EADDRINUSE; 1568 1569 ip_rsvpd = so; 1570 /* 1571 * This may seem silly, but we need to be sure we don't over-increment 1572 * the RSVP counter, in case something slips up. 1573 */ 1574 if (!ip_rsvp_on) { 1575 ip_rsvp_on = 1; 1576 rsvp_on++; 1577 } 1578 1579 return 0; 1580 } 1581 1582 int 1583 ip_rsvp_done(void) 1584 { 1585 ip_rsvpd = NULL; 1586 /* 1587 * This may seem silly, but we need to be sure we don't over-decrement 1588 * the RSVP counter, in case something slips up. 1589 */ 1590 if (ip_rsvp_on) { 1591 ip_rsvp_on = 0; 1592 rsvp_on--; 1593 } 1594 return 0; 1595 } 1596 1597 void 1598 rsvp_input(struct mbuf *m, int off) /* XXX must fixup manually */ 1599 { 1600 if (rsvp_input_p) { /* call the real one if loaded */ 1601 rsvp_input_p(m, off); 1602 return; 1603 } 1604 1605 /* Can still get packets with rsvp_on = 0 if there is a local member 1606 * of the group to which the RSVP packet is addressed. But in this 1607 * case we want to throw the packet away. 1608 */ 1609 1610 if (!rsvp_on) { 1611 m_freem(m); 1612 return; 1613 } 1614 1615 if (ip_rsvpd != NULL) { 1616 rip_input(m, off); 1617 return; 1618 } 1619 /* Drop the packet */ 1620 m_freem(m); 1621 } 1622