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 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/mbuf.h> 44#include <sys/malloc.h> 45#include <sys/domain.h> 46#include <sys/protosw.h> 47#include <sys/socket.h> 48#include <sys/time.h> 49#include <sys/kernel.h> 50#include <sys/lock.h> 51#include <sys/rwlock.h> 52#include <sys/sdt.h> 53#include <sys/syslog.h> 54#include <sys/sysctl.h> 55 56#include <net/pfil.h> 57#include <net/if.h> 58#include <net/if_types.h> 59#include <net/if_var.h> 60#include <net/if_dl.h> 61#include <net/route.h> 62#include <net/netisr.h> 63#include <net/vnet.h> 64 65#include <netinet/in.h> 66#include <netinet/in_kdtrace.h> 67#include <netinet/in_systm.h> 68#include <netinet/in_var.h> 69#include <netinet/ip.h> 70#include <netinet/in_pcb.h> 71#include <netinet/ip_var.h> 72#include <netinet/ip_fw.h> 73#include <netinet/ip_icmp.h> 74#include <netinet/ip_options.h> 75#include <machine/in_cksum.h> 76#include <netinet/ip_carp.h> 77#ifdef IPSEC 78#include <netinet/ip_ipsec.h> 79#endif /* IPSEC */ 80 81#include <sys/socketvar.h> 82 83#include <security/mac/mac_framework.h> 84 85#ifdef CTASSERT 86CTASSERT(sizeof(struct ip) == 20); 87#endif 88 89struct rwlock in_ifaddr_lock; 90RW_SYSINIT(in_ifaddr_lock, &in_ifaddr_lock, "in_ifaddr_lock"); 91 92VNET_DEFINE(int, rsvp_on); 93 94VNET_DEFINE(int, ipforwarding); 95SYSCTL_VNET_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW, 96 &VNET_NAME(ipforwarding), 0, 97 "Enable IP forwarding between interfaces"); 98 99static VNET_DEFINE(int, ipsendredirects) = 1; /* XXX */ 100#define V_ipsendredirects VNET(ipsendredirects) 101SYSCTL_VNET_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW, 102 &VNET_NAME(ipsendredirects), 0, 103 "Enable sending IP redirects"); 104 105static VNET_DEFINE(int, ip_keepfaith); 106#define V_ip_keepfaith VNET(ip_keepfaith) 107SYSCTL_VNET_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW, 108 &VNET_NAME(ip_keepfaith), 0, 109 "Enable packet capture for FAITH IPv4->IPv6 translater daemon"); 110 111static VNET_DEFINE(int, ip_sendsourcequench); 112#define V_ip_sendsourcequench VNET(ip_sendsourcequench) 113SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW, 114 &VNET_NAME(ip_sendsourcequench), 0, 115 "Enable the transmission of source quench packets"); 116 117VNET_DEFINE(int, ip_do_randomid); 118SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW, 119 &VNET_NAME(ip_do_randomid), 0, 120 "Assign random ip_id values"); 121 122/* 123 * XXX - Setting ip_checkinterface mostly implements the receive side of 124 * the Strong ES model described in RFC 1122, but since the routing table 125 * and transmit implementation do not implement the Strong ES model, 126 * setting this to 1 results in an odd hybrid. 127 * 128 * XXX - ip_checkinterface currently must be disabled if you use ipnat 129 * to translate the destination address to another local interface. 130 * 131 * XXX - ip_checkinterface must be disabled if you add IP aliases 132 * to the loopback interface instead of the interface where the 133 * packets for those addresses are received. 134 */ 135static VNET_DEFINE(int, ip_checkinterface); 136#define V_ip_checkinterface VNET(ip_checkinterface) 137SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW, 138 &VNET_NAME(ip_checkinterface), 0, 139 "Verify packet arrives on correct interface"); 140 141VNET_DEFINE(struct pfil_head, inet_pfil_hook); /* Packet filter hooks */ 142 143static struct netisr_handler ip_nh = { 144 .nh_name = "ip", 145 .nh_handler = ip_input, 146 .nh_proto = NETISR_IP, 147 .nh_policy = NETISR_POLICY_FLOW, 148}; 149 150extern struct domain inetdomain; 151extern struct protosw inetsw[]; 152u_char ip_protox[IPPROTO_MAX]; 153VNET_DEFINE(struct in_ifaddrhead, in_ifaddrhead); /* first inet address */ 154VNET_DEFINE(struct in_ifaddrhashhead *, in_ifaddrhashtbl); /* inet addr hash table */ 155VNET_DEFINE(u_long, in_ifaddrhmask); /* mask for hash table */ 156 157static VNET_DEFINE(uma_zone_t, ipq_zone); 158static VNET_DEFINE(TAILQ_HEAD(ipqhead, ipq), ipq[IPREASS_NHASH]); 159static struct mtx ipqlock; 160 161#define V_ipq_zone VNET(ipq_zone) 162#define V_ipq VNET(ipq) 163 164#define IPQ_LOCK() mtx_lock(&ipqlock) 165#define IPQ_UNLOCK() mtx_unlock(&ipqlock) 166#define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF) 167#define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED) 168 169static void maxnipq_update(void); 170static void ipq_zone_change(void *); 171static void ip_drain_locked(void); 172 173static VNET_DEFINE(int, maxnipq); /* Administrative limit on # reass queues. */ 174static VNET_DEFINE(int, nipq); /* Total # of reass queues */ 175#define V_maxnipq VNET(maxnipq) 176#define V_nipq VNET(nipq) 177SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_RD, 178 &VNET_NAME(nipq), 0, 179 "Current number of IPv4 fragment reassembly queue entries"); 180 181static VNET_DEFINE(int, maxfragsperpacket); 182#define V_maxfragsperpacket VNET(maxfragsperpacket) 183SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW, 184 &VNET_NAME(maxfragsperpacket), 0, 185 "Maximum number of IPv4 fragments allowed per packet"); 186 187#ifdef IPCTL_DEFMTU 188SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, 189 &ip_mtu, 0, "Default MTU"); 190#endif 191 192#ifdef IPSTEALTH 193VNET_DEFINE(int, ipstealth); 194SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW, 195 &VNET_NAME(ipstealth), 0, 196 "IP stealth mode, no TTL decrementation on forwarding"); 197#endif 198 199static void ip_freef(struct ipqhead *, struct ipq *); 200 201/* 202 * IP statistics are stored in the "array" of counter(9)s. 203 */ 204VNET_PCPUSTAT_DEFINE(struct ipstat, ipstat); 205VNET_PCPUSTAT_SYSINIT(ipstat); 206SYSCTL_VNET_PCPUSTAT(_net_inet_ip, IPCTL_STATS, stats, struct ipstat, ipstat, 207 "IP statistics (struct ipstat, netinet/ip_var.h)"); 208 209#ifdef VIMAGE 210VNET_PCPUSTAT_SYSUNINIT(ipstat); 211#endif /* VIMAGE */ 212 213/* 214 * Kernel module interface for updating ipstat. The argument is an index 215 * into ipstat treated as an array. 216 */ 217void 218kmod_ipstat_inc(int statnum) 219{ 220 221 counter_u64_add(VNET(ipstat)[statnum], 1); 222} 223 224void 225kmod_ipstat_dec(int statnum) 226{ 227 228 counter_u64_add(VNET(ipstat)[statnum], -1); 229} 230 231static int 232sysctl_netinet_intr_queue_maxlen(SYSCTL_HANDLER_ARGS) 233{ 234 int error, qlimit; 235 236 netisr_getqlimit(&ip_nh, &qlimit); 237 error = sysctl_handle_int(oidp, &qlimit, 0, req); 238 if (error || !req->newptr) 239 return (error); 240 if (qlimit < 1) 241 return (EINVAL); 242 return (netisr_setqlimit(&ip_nh, qlimit)); 243} 244SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, 245 CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_queue_maxlen, "I", 246 "Maximum size of the IP input queue"); 247 248static int 249sysctl_netinet_intr_queue_drops(SYSCTL_HANDLER_ARGS) 250{ 251 u_int64_t qdrops_long; 252 int error, qdrops; 253 254 netisr_getqdrops(&ip_nh, &qdrops_long); 255 qdrops = qdrops_long; 256 error = sysctl_handle_int(oidp, &qdrops, 0, req); 257 if (error || !req->newptr) 258 return (error); 259 if (qdrops != 0) 260 return (EINVAL); 261 netisr_clearqdrops(&ip_nh); 262 return (0); 263} 264 265SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, 266 CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_queue_drops, "I", 267 "Number of packets dropped from the IP input queue"); 268 269/* 270 * IP initialization: fill in IP protocol switch table. 271 * All protocols not implemented in kernel go to raw IP protocol handler. 272 */ 273void 274ip_init(void) 275{ 276 struct protosw *pr; 277 int i; 278 279 V_ip_id = time_second & 0xffff; 280 281 TAILQ_INIT(&V_in_ifaddrhead); 282 V_in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &V_in_ifaddrhmask); 283 284 /* Initialize IP reassembly queue. */ 285 for (i = 0; i < IPREASS_NHASH; i++) 286 TAILQ_INIT(&V_ipq[i]); 287 V_maxnipq = nmbclusters / 32; 288 V_maxfragsperpacket = 16; 289 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL, 290 NULL, UMA_ALIGN_PTR, 0); 291 maxnipq_update(); 292 293 /* Initialize packet filter hooks. */ 294 V_inet_pfil_hook.ph_type = PFIL_TYPE_AF; 295 V_inet_pfil_hook.ph_af = AF_INET; 296 if ((i = pfil_head_register(&V_inet_pfil_hook)) != 0) 297 printf("%s: WARNING: unable to register pfil hook, " 298 "error %d\n", __func__, i); 299 300 /* Skip initialization of globals for non-default instances. */ 301 if (!IS_DEFAULT_VNET(curvnet)) 302 return; 303 304 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 305 if (pr == NULL) 306 panic("ip_init: PF_INET not found"); 307 308 /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */ 309 for (i = 0; i < IPPROTO_MAX; i++) 310 ip_protox[i] = pr - inetsw; 311 /* 312 * Cycle through IP protocols and put them into the appropriate place 313 * in ip_protox[]. 314 */ 315 for (pr = inetdomain.dom_protosw; 316 pr < inetdomain.dom_protoswNPROTOSW; pr++) 317 if (pr->pr_domain->dom_family == PF_INET && 318 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) { 319 /* Be careful to only index valid IP protocols. */ 320 if (pr->pr_protocol < IPPROTO_MAX) 321 ip_protox[pr->pr_protocol] = pr - inetsw; 322 } 323 324 EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change, 325 NULL, EVENTHANDLER_PRI_ANY); 326 327 /* Initialize various other remaining things. */ 328 IPQ_LOCK_INIT(); 329 netisr_register(&ip_nh); 330} 331 332#ifdef VIMAGE 333void 334ip_destroy(void) 335{ 336 int i; 337 338 if ((i = pfil_head_unregister(&V_inet_pfil_hook)) != 0) 339 printf("%s: WARNING: unable to unregister pfil hook, " 340 "error %d\n", __func__, i); 341 342 /* Cleanup in_ifaddr hash table; should be empty. */ 343 hashdestroy(V_in_ifaddrhashtbl, M_IFADDR, V_in_ifaddrhmask); 344 345 IPQ_LOCK(); 346 ip_drain_locked(); 347 IPQ_UNLOCK(); 348 349 uma_zdestroy(V_ipq_zone); 350} 351#endif 352 353/* 354 * Ip input routine. Checksum and byte swap header. If fragmented 355 * try to reassemble. Process options. Pass to next level. 356 */ 357void 358ip_input(struct mbuf *m) 359{ 360 struct ip *ip = NULL; 361 struct in_ifaddr *ia = NULL; 362 struct ifaddr *ifa; 363 struct ifnet *ifp; 364 int checkif, hlen = 0; 365 uint16_t sum, ip_len; 366 int dchg = 0; /* dest changed after fw */ 367 struct in_addr odst; /* original dst address */ 368 369 M_ASSERTPKTHDR(m); 370 371 if (m->m_flags & M_FASTFWD_OURS) { 372 m->m_flags &= ~M_FASTFWD_OURS; 373 /* Set up some basics that will be used later. */ 374 ip = mtod(m, struct ip *); 375 hlen = ip->ip_hl << 2; 376 ip_len = ntohs(ip->ip_len); 377 goto ours; 378 } 379 380 IPSTAT_INC(ips_total); 381 382 if (m->m_pkthdr.len < sizeof(struct ip)) 383 goto tooshort; 384 385 if (m->m_len < sizeof (struct ip) && 386 (m = m_pullup(m, sizeof (struct ip))) == NULL) { 387 IPSTAT_INC(ips_toosmall); 388 return; 389 } 390 ip = mtod(m, struct ip *); 391 392 if (ip->ip_v != IPVERSION) { 393 IPSTAT_INC(ips_badvers); 394 goto bad; 395 } 396 397 hlen = ip->ip_hl << 2; 398 if (hlen < sizeof(struct ip)) { /* minimum header length */ 399 IPSTAT_INC(ips_badhlen); 400 goto bad; 401 } 402 if (hlen > m->m_len) { 403 if ((m = m_pullup(m, hlen)) == NULL) { 404 IPSTAT_INC(ips_badhlen); 405 return; 406 } 407 ip = mtod(m, struct ip *); 408 } 409 410 IP_PROBE(receive, NULL, NULL, ip, m->m_pkthdr.rcvif, ip, NULL); 411 412 /* 127/8 must not appear on wire - RFC1122 */ 413 ifp = m->m_pkthdr.rcvif; 414 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 415 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 416 if ((ifp->if_flags & IFF_LOOPBACK) == 0) { 417 IPSTAT_INC(ips_badaddr); 418 goto bad; 419 } 420 } 421 422 if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) { 423 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 424 } else { 425 if (hlen == sizeof(struct ip)) { 426 sum = in_cksum_hdr(ip); 427 } else { 428 sum = in_cksum(m, hlen); 429 } 430 } 431 if (sum) { 432 IPSTAT_INC(ips_badsum); 433 goto bad; 434 } 435 436#ifdef ALTQ 437 if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 438 /* packet is dropped by traffic conditioner */ 439 return; 440#endif 441 442 ip_len = ntohs(ip->ip_len); 443 if (ip_len < hlen) { 444 IPSTAT_INC(ips_badlen); 445 goto bad; 446 } 447 448 /* 449 * Check that the amount of data in the buffers 450 * is as at least much as the IP header would have us expect. 451 * Trim mbufs if longer than we expect. 452 * Drop packet if shorter than we expect. 453 */ 454 if (m->m_pkthdr.len < ip_len) { 455tooshort: 456 IPSTAT_INC(ips_tooshort); 457 goto bad; 458 } 459 if (m->m_pkthdr.len > ip_len) { 460 if (m->m_len == m->m_pkthdr.len) { 461 m->m_len = ip_len; 462 m->m_pkthdr.len = ip_len; 463 } else 464 m_adj(m, ip_len - m->m_pkthdr.len); 465 } 466#ifdef IPSEC 467 /* 468 * Bypass packet filtering for packets previously handled by IPsec. 469 */ 470 if (ip_ipsec_filtertunnel(m)) 471 goto passin; 472#endif /* IPSEC */ 473 474 /* 475 * Run through list of hooks for input packets. 476 * 477 * NB: Beware of the destination address changing (e.g. 478 * by NAT rewriting). When this happens, tell 479 * ip_forward to do the right thing. 480 */ 481 482 /* Jump over all PFIL processing if hooks are not active. */ 483 if (!PFIL_HOOKED(&V_inet_pfil_hook)) 484 goto passin; 485 486 odst = ip->ip_dst; 487 if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_IN, NULL) != 0) 488 return; 489 if (m == NULL) /* consumed by filter */ 490 return; 491 492 ip = mtod(m, struct ip *); 493 dchg = (odst.s_addr != ip->ip_dst.s_addr); 494 ifp = m->m_pkthdr.rcvif; 495 496 if (m->m_flags & M_FASTFWD_OURS) { 497 m->m_flags &= ~M_FASTFWD_OURS; 498 goto ours; 499 } 500 if (m->m_flags & M_IP_NEXTHOP) { 501 dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL); 502 if (dchg != 0) { 503 /* 504 * Directly ship the packet on. This allows 505 * forwarding packets originally destined to us 506 * to some other directly connected host. 507 */ 508 ip_forward(m, 1); 509 return; 510 } 511 } 512passin: 513 514 /* 515 * Process options and, if not destined for us, 516 * ship it on. ip_dooptions returns 1 when an 517 * error was detected (causing an icmp message 518 * to be sent and the original packet to be freed). 519 */ 520 if (hlen > sizeof (struct ip) && ip_dooptions(m, 0)) 521 return; 522 523 /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no 524 * matter if it is destined to another node, or whether it is 525 * a multicast one, RSVP wants it! and prevents it from being forwarded 526 * anywhere else. Also checks if the rsvp daemon is running before 527 * grabbing the packet. 528 */ 529 if (V_rsvp_on && ip->ip_p==IPPROTO_RSVP) 530 goto ours; 531 532 /* 533 * Check our list of addresses, to see if the packet is for us. 534 * If we don't have any addresses, assume any unicast packet 535 * we receive might be for us (and let the upper layers deal 536 * with it). 537 */ 538 if (TAILQ_EMPTY(&V_in_ifaddrhead) && 539 (m->m_flags & (M_MCAST|M_BCAST)) == 0) 540 goto ours; 541 542 /* 543 * Enable a consistency check between the destination address 544 * and the arrival interface for a unicast packet (the RFC 1122 545 * strong ES model) if IP forwarding is disabled and the packet 546 * is not locally generated and the packet is not subject to 547 * 'ipfw fwd'. 548 * 549 * XXX - Checking also should be disabled if the destination 550 * address is ipnat'ed to a different interface. 551 * 552 * XXX - Checking is incompatible with IP aliases added 553 * to the loopback interface instead of the interface where 554 * the packets are received. 555 * 556 * XXX - This is the case for carp vhost IPs as well so we 557 * insert a workaround. If the packet got here, we already 558 * checked with carp_iamatch() and carp_forus(). 559 */ 560 checkif = V_ip_checkinterface && (V_ipforwarding == 0) && 561 ifp != NULL && ((ifp->if_flags & IFF_LOOPBACK) == 0) && 562 ifp->if_carp == NULL && (dchg == 0); 563 564 /* 565 * Check for exact addresses in the hash bucket. 566 */ 567 /* IN_IFADDR_RLOCK(); */ 568 LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) { 569 /* 570 * If the address matches, verify that the packet 571 * arrived via the correct interface if checking is 572 * enabled. 573 */ 574 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr && 575 (!checkif || ia->ia_ifp == ifp)) { 576 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 577 counter_u64_add(ia->ia_ifa.ifa_ibytes, 578 m->m_pkthdr.len); 579 /* IN_IFADDR_RUNLOCK(); */ 580 goto ours; 581 } 582 } 583 /* IN_IFADDR_RUNLOCK(); */ 584 585 /* 586 * Check for broadcast addresses. 587 * 588 * Only accept broadcast packets that arrive via the matching 589 * interface. Reception of forwarded directed broadcasts would 590 * be handled via ip_forward() and ether_output() with the loopback 591 * into the stack for SIMPLEX interfaces handled by ether_output(). 592 */ 593 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 594 IF_ADDR_RLOCK(ifp); 595 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 596 if (ifa->ifa_addr->sa_family != AF_INET) 597 continue; 598 ia = ifatoia(ifa); 599 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 600 ip->ip_dst.s_addr) { 601 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 602 counter_u64_add(ia->ia_ifa.ifa_ibytes, 603 m->m_pkthdr.len); 604 IF_ADDR_RUNLOCK(ifp); 605 goto ours; 606 } 607#ifdef BOOTP_COMPAT 608 if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) { 609 counter_u64_add(ia->ia_ifa.ifa_ipackets, 1); 610 counter_u64_add(ia->ia_ifa.ifa_ibytes, 611 m->m_pkthdr.len); 612 IF_ADDR_RUNLOCK(ifp); 613 goto ours; 614 } 615#endif 616 } 617 IF_ADDR_RUNLOCK(ifp); 618 ia = NULL; 619 } 620 /* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */ 621 if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) { 622 IPSTAT_INC(ips_cantforward); 623 m_freem(m); 624 return; 625 } 626 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 627 if (V_ip_mrouter) { 628 /* 629 * If we are acting as a multicast router, all 630 * incoming multicast packets are passed to the 631 * kernel-level multicast forwarding function. 632 * The packet is returned (relatively) intact; if 633 * ip_mforward() returns a non-zero value, the packet 634 * must be discarded, else it may be accepted below. 635 */ 636 if (ip_mforward && ip_mforward(ip, ifp, m, 0) != 0) { 637 IPSTAT_INC(ips_cantforward); 638 m_freem(m); 639 return; 640 } 641 642 /* 643 * The process-level routing daemon needs to receive 644 * all multicast IGMP packets, whether or not this 645 * host belongs to their destination groups. 646 */ 647 if (ip->ip_p == IPPROTO_IGMP) 648 goto ours; 649 IPSTAT_INC(ips_forward); 650 } 651 /* 652 * Assume the packet is for us, to avoid prematurely taking 653 * a lock on the in_multi hash. Protocols must perform 654 * their own filtering and update statistics accordingly. 655 */ 656 goto ours; 657 } 658 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 659 goto ours; 660 if (ip->ip_dst.s_addr == INADDR_ANY) 661 goto ours; 662 663 /* 664 * FAITH(Firewall Aided Internet Translator) 665 */ 666 if (ifp && ifp->if_type == IFT_FAITH) { 667 if (V_ip_keepfaith) { 668 if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP) 669 goto ours; 670 } 671 m_freem(m); 672 return; 673 } 674 675 /* 676 * Not for us; forward if possible and desirable. 677 */ 678 if (V_ipforwarding == 0) { 679 IPSTAT_INC(ips_cantforward); 680 m_freem(m); 681 } else { 682#ifdef IPSEC 683 if (ip_ipsec_fwd(m)) 684 goto bad; 685#endif /* IPSEC */ 686 ip_forward(m, dchg); 687 } 688 return; 689 690ours: 691#ifdef IPSTEALTH 692 /* 693 * IPSTEALTH: Process non-routing options only 694 * if the packet is destined for us. 695 */ 696 if (V_ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1)) 697 return; 698#endif /* IPSTEALTH */ 699 700 /* 701 * Attempt reassembly; if it succeeds, proceed. 702 * ip_reass() will return a different mbuf. 703 */ 704 if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) { 705 m = ip_reass(m); 706 if (m == NULL) 707 return; 708 ip = mtod(m, struct ip *); 709 /* Get the header length of the reassembled packet */ 710 hlen = ip->ip_hl << 2; 711 } 712 713#ifdef IPSEC 714 /* 715 * enforce IPsec policy checking if we are seeing last header. 716 * note that we do not visit this with protocols with pcb layer 717 * code - like udp/tcp/raw ip. 718 */ 719 if (ip_ipsec_input(m)) 720 goto bad; 721#endif /* IPSEC */ 722 723 /* 724 * Switch out to protocol's input routine. 725 */ 726 IPSTAT_INC(ips_delivered); 727 728 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 729 return; 730bad: 731 m_freem(m); 732} 733 734/* 735 * After maxnipq has been updated, propagate the change to UMA. The UMA zone 736 * max has slightly different semantics than the sysctl, for historical 737 * reasons. 738 */ 739static void 740maxnipq_update(void) 741{ 742 743 /* 744 * -1 for unlimited allocation. 745 */ 746 if (V_maxnipq < 0) 747 uma_zone_set_max(V_ipq_zone, 0); 748 /* 749 * Positive number for specific bound. 750 */ 751 if (V_maxnipq > 0) 752 uma_zone_set_max(V_ipq_zone, V_maxnipq); 753 /* 754 * Zero specifies no further fragment queue allocation -- set the 755 * bound very low, but rely on implementation elsewhere to actually 756 * prevent allocation and reclaim current queues. 757 */ 758 if (V_maxnipq == 0) 759 uma_zone_set_max(V_ipq_zone, 1); 760} 761 762static void 763ipq_zone_change(void *tag) 764{ 765 766 if (V_maxnipq > 0 && V_maxnipq < (nmbclusters / 32)) { 767 V_maxnipq = nmbclusters / 32; 768 maxnipq_update(); 769 } 770} 771 772static int 773sysctl_maxnipq(SYSCTL_HANDLER_ARGS) 774{ 775 int error, i; 776 777 i = V_maxnipq; 778 error = sysctl_handle_int(oidp, &i, 0, req); 779 if (error || !req->newptr) 780 return (error); 781 782 /* 783 * XXXRW: Might be a good idea to sanity check the argument and place 784 * an extreme upper bound. 785 */ 786 if (i < -1) 787 return (EINVAL); 788 V_maxnipq = i; 789 maxnipq_update(); 790 return (0); 791} 792 793SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW, 794 NULL, 0, sysctl_maxnipq, "I", 795 "Maximum number of IPv4 fragment reassembly queue entries"); 796 797/* 798 * Take incoming datagram fragment and try to reassemble it into 799 * whole datagram. If the argument is the first fragment or one 800 * in between the function will return NULL and store the mbuf 801 * in the fragment chain. If the argument is the last fragment 802 * the packet will be reassembled and the pointer to the new 803 * mbuf returned for further processing. Only m_tags attached 804 * to the first packet/fragment are preserved. 805 * The IP header is *NOT* adjusted out of iplen. 806 */ 807struct mbuf * 808ip_reass(struct mbuf *m) 809{ 810 struct ip *ip; 811 struct mbuf *p, *q, *nq, *t; 812 struct ipq *fp = NULL; 813 struct ipqhead *head; 814 int i, hlen, next; 815 u_int8_t ecn, ecn0; 816 u_short hash; 817 818 /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */ 819 if (V_maxnipq == 0 || V_maxfragsperpacket == 0) { 820 IPSTAT_INC(ips_fragments); 821 IPSTAT_INC(ips_fragdropped); 822 m_freem(m); 823 return (NULL); 824 } 825 826 ip = mtod(m, struct ip *); 827 hlen = ip->ip_hl << 2; 828 829 hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); 830 head = &V_ipq[hash]; 831 IPQ_LOCK(); 832 833 /* 834 * Look for queue of fragments 835 * of this datagram. 836 */ 837 TAILQ_FOREACH(fp, head, ipq_list) 838 if (ip->ip_id == fp->ipq_id && 839 ip->ip_src.s_addr == fp->ipq_src.s_addr && 840 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 841#ifdef MAC 842 mac_ipq_match(m, fp) && 843#endif 844 ip->ip_p == fp->ipq_p) 845 goto found; 846 847 fp = NULL; 848 849 /* 850 * Attempt to trim the number of allocated fragment queues if it 851 * exceeds the administrative limit. 852 */ 853 if ((V_nipq > V_maxnipq) && (V_maxnipq > 0)) { 854 /* 855 * drop something from the tail of the current queue 856 * before proceeding further 857 */ 858 struct ipq *q = TAILQ_LAST(head, ipqhead); 859 if (q == NULL) { /* gak */ 860 for (i = 0; i < IPREASS_NHASH; i++) { 861 struct ipq *r = TAILQ_LAST(&V_ipq[i], ipqhead); 862 if (r) { 863 IPSTAT_ADD(ips_fragtimeout, 864 r->ipq_nfrags); 865 ip_freef(&V_ipq[i], r); 866 break; 867 } 868 } 869 } else { 870 IPSTAT_ADD(ips_fragtimeout, q->ipq_nfrags); 871 ip_freef(head, q); 872 } 873 } 874 875found: 876 /* 877 * Adjust ip_len to not reflect header, 878 * convert offset of this to bytes. 879 */ 880 ip->ip_len = htons(ntohs(ip->ip_len) - hlen); 881 if (ip->ip_off & htons(IP_MF)) { 882 /* 883 * Make sure that fragments have a data length 884 * that's a non-zero multiple of 8 bytes. 885 */ 886 if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) { 887 IPSTAT_INC(ips_toosmall); /* XXX */ 888 goto dropfrag; 889 } 890 m->m_flags |= M_IP_FRAG; 891 } else 892 m->m_flags &= ~M_IP_FRAG; 893 ip->ip_off = htons(ntohs(ip->ip_off) << 3); 894 895 /* 896 * Attempt reassembly; if it succeeds, proceed. 897 * ip_reass() will return a different mbuf. 898 */ 899 IPSTAT_INC(ips_fragments); 900 m->m_pkthdr.PH_loc.ptr = ip; 901 902 /* Previous ip_reass() started here. */ 903 /* 904 * Presence of header sizes in mbufs 905 * would confuse code below. 906 */ 907 m->m_data += hlen; 908 m->m_len -= hlen; 909 910 /* 911 * If first fragment to arrive, create a reassembly queue. 912 */ 913 if (fp == NULL) { 914 fp = uma_zalloc(V_ipq_zone, M_NOWAIT); 915 if (fp == NULL) 916 goto dropfrag; 917#ifdef MAC 918 if (mac_ipq_init(fp, M_NOWAIT) != 0) { 919 uma_zfree(V_ipq_zone, fp); 920 fp = NULL; 921 goto dropfrag; 922 } 923 mac_ipq_create(m, fp); 924#endif 925 TAILQ_INSERT_HEAD(head, fp, ipq_list); 926 V_nipq++; 927 fp->ipq_nfrags = 1; 928 fp->ipq_ttl = IPFRAGTTL; 929 fp->ipq_p = ip->ip_p; 930 fp->ipq_id = ip->ip_id; 931 fp->ipq_src = ip->ip_src; 932 fp->ipq_dst = ip->ip_dst; 933 fp->ipq_frags = m; 934 m->m_nextpkt = NULL; 935 goto done; 936 } else { 937 fp->ipq_nfrags++; 938#ifdef MAC 939 mac_ipq_update(m, fp); 940#endif 941 } 942 943#define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr)) 944 945 /* 946 * Handle ECN by comparing this segment with the first one; 947 * if CE is set, do not lose CE. 948 * drop if CE and not-ECT are mixed for the same packet. 949 */ 950 ecn = ip->ip_tos & IPTOS_ECN_MASK; 951 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; 952 if (ecn == IPTOS_ECN_CE) { 953 if (ecn0 == IPTOS_ECN_NOTECT) 954 goto dropfrag; 955 if (ecn0 != IPTOS_ECN_CE) 956 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE; 957 } 958 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) 959 goto dropfrag; 960 961 /* 962 * Find a segment which begins after this one does. 963 */ 964 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) 965 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off)) 966 break; 967 968 /* 969 * If there is a preceding segment, it may provide some of 970 * our data already. If so, drop the data from the incoming 971 * segment. If it provides all of our data, drop us, otherwise 972 * stick new segment in the proper place. 973 * 974 * If some of the data is dropped from the preceding 975 * segment, then it's checksum is invalidated. 976 */ 977 if (p) { 978 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) - 979 ntohs(ip->ip_off); 980 if (i > 0) { 981 if (i >= ntohs(ip->ip_len)) 982 goto dropfrag; 983 m_adj(m, i); 984 m->m_pkthdr.csum_flags = 0; 985 ip->ip_off = htons(ntohs(ip->ip_off) + i); 986 ip->ip_len = htons(ntohs(ip->ip_len) - i); 987 } 988 m->m_nextpkt = p->m_nextpkt; 989 p->m_nextpkt = m; 990 } else { 991 m->m_nextpkt = fp->ipq_frags; 992 fp->ipq_frags = m; 993 } 994 995 /* 996 * While we overlap succeeding segments trim them or, 997 * if they are completely covered, dequeue them. 998 */ 999 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) > 1000 ntohs(GETIP(q)->ip_off); q = nq) { 1001 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) - 1002 ntohs(GETIP(q)->ip_off); 1003 if (i < ntohs(GETIP(q)->ip_len)) { 1004 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i); 1005 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i); 1006 m_adj(q, i); 1007 q->m_pkthdr.csum_flags = 0; 1008 break; 1009 } 1010 nq = q->m_nextpkt; 1011 m->m_nextpkt = nq; 1012 IPSTAT_INC(ips_fragdropped); 1013 fp->ipq_nfrags--; 1014 m_freem(q); 1015 } 1016 1017 /* 1018 * Check for complete reassembly and perform frag per packet 1019 * limiting. 1020 * 1021 * Frag limiting is performed here so that the nth frag has 1022 * a chance to complete the packet before we drop the packet. 1023 * As a result, n+1 frags are actually allowed per packet, but 1024 * only n will ever be stored. (n = maxfragsperpacket.) 1025 * 1026 */ 1027 next = 0; 1028 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { 1029 if (ntohs(GETIP(q)->ip_off) != next) { 1030 if (fp->ipq_nfrags > V_maxfragsperpacket) { 1031 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1032 ip_freef(head, fp); 1033 } 1034 goto done; 1035 } 1036 next += ntohs(GETIP(q)->ip_len); 1037 } 1038 /* Make sure the last packet didn't have the IP_MF flag */ 1039 if (p->m_flags & M_IP_FRAG) { 1040 if (fp->ipq_nfrags > V_maxfragsperpacket) { 1041 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1042 ip_freef(head, fp); 1043 } 1044 goto done; 1045 } 1046 1047 /* 1048 * Reassembly is complete. Make sure the packet is a sane size. 1049 */ 1050 q = fp->ipq_frags; 1051 ip = GETIP(q); 1052 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { 1053 IPSTAT_INC(ips_toolong); 1054 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 1055 ip_freef(head, fp); 1056 goto done; 1057 } 1058 1059 /* 1060 * Concatenate fragments. 1061 */ 1062 m = q; 1063 t = m->m_next; 1064 m->m_next = NULL; 1065 m_cat(m, t); 1066 nq = q->m_nextpkt; 1067 q->m_nextpkt = NULL; 1068 for (q = nq; q != NULL; q = nq) { 1069 nq = q->m_nextpkt; 1070 q->m_nextpkt = NULL; 1071 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; 1072 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; 1073 m_cat(m, q); 1074 } 1075 /* 1076 * In order to do checksumming faster we do 'end-around carry' here 1077 * (and not in for{} loop), though it implies we are not going to 1078 * reassemble more than 64k fragments. 1079 */ 1080 m->m_pkthdr.csum_data = 1081 (m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16); 1082#ifdef MAC 1083 mac_ipq_reassemble(fp, m); 1084 mac_ipq_destroy(fp); 1085#endif 1086 1087 /* 1088 * Create header for new ip packet by modifying header of first 1089 * packet; dequeue and discard fragment reassembly header. 1090 * Make header visible. 1091 */ 1092 ip->ip_len = htons((ip->ip_hl << 2) + next); 1093 ip->ip_src = fp->ipq_src; 1094 ip->ip_dst = fp->ipq_dst; 1095 TAILQ_REMOVE(head, fp, ipq_list); 1096 V_nipq--; 1097 uma_zfree(V_ipq_zone, fp); 1098 m->m_len += (ip->ip_hl << 2); 1099 m->m_data -= (ip->ip_hl << 2); 1100 /* some debugging cruft by sklower, below, will go away soon */ 1101 if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */ 1102 m_fixhdr(m); 1103 IPSTAT_INC(ips_reassembled); 1104 IPQ_UNLOCK(); 1105 return (m); 1106 1107dropfrag: 1108 IPSTAT_INC(ips_fragdropped); 1109 if (fp != NULL) 1110 fp->ipq_nfrags--; 1111 m_freem(m); 1112done: 1113 IPQ_UNLOCK(); 1114 return (NULL); 1115 1116#undef GETIP 1117} 1118 1119/* 1120 * Free a fragment reassembly header and all 1121 * associated datagrams. 1122 */ 1123static void 1124ip_freef(struct ipqhead *fhp, struct ipq *fp) 1125{ 1126 struct mbuf *q; 1127 1128 IPQ_LOCK_ASSERT(); 1129 1130 while (fp->ipq_frags) { 1131 q = fp->ipq_frags; 1132 fp->ipq_frags = q->m_nextpkt; 1133 m_freem(q); 1134 } 1135 TAILQ_REMOVE(fhp, fp, ipq_list); 1136 uma_zfree(V_ipq_zone, fp); 1137 V_nipq--; 1138} 1139 1140/* 1141 * IP timer processing; 1142 * if a timer expires on a reassembly 1143 * queue, discard it. 1144 */ 1145void 1146ip_slowtimo(void) 1147{ 1148 VNET_ITERATOR_DECL(vnet_iter); 1149 struct ipq *fp; 1150 int i; 1151 1152 VNET_LIST_RLOCK_NOSLEEP(); 1153 IPQ_LOCK(); 1154 VNET_FOREACH(vnet_iter) { 1155 CURVNET_SET(vnet_iter); 1156 for (i = 0; i < IPREASS_NHASH; i++) { 1157 for(fp = TAILQ_FIRST(&V_ipq[i]); fp;) { 1158 struct ipq *fpp; 1159 1160 fpp = fp; 1161 fp = TAILQ_NEXT(fp, ipq_list); 1162 if(--fpp->ipq_ttl == 0) { 1163 IPSTAT_ADD(ips_fragtimeout, 1164 fpp->ipq_nfrags); 1165 ip_freef(&V_ipq[i], fpp); 1166 } 1167 } 1168 } 1169 /* 1170 * If we are over the maximum number of fragments 1171 * (due to the limit being lowered), drain off 1172 * enough to get down to the new limit. 1173 */ 1174 if (V_maxnipq >= 0 && V_nipq > V_maxnipq) { 1175 for (i = 0; i < IPREASS_NHASH; i++) { 1176 while (V_nipq > V_maxnipq && 1177 !TAILQ_EMPTY(&V_ipq[i])) { 1178 IPSTAT_ADD(ips_fragdropped, 1179 TAILQ_FIRST(&V_ipq[i])->ipq_nfrags); 1180 ip_freef(&V_ipq[i], 1181 TAILQ_FIRST(&V_ipq[i])); 1182 } 1183 } 1184 } 1185 CURVNET_RESTORE(); 1186 } 1187 IPQ_UNLOCK(); 1188 VNET_LIST_RUNLOCK_NOSLEEP(); 1189} 1190 1191/* 1192 * Drain off all datagram fragments. 1193 */ 1194static void 1195ip_drain_locked(void) 1196{ 1197 int i; 1198 1199 IPQ_LOCK_ASSERT(); 1200 1201 for (i = 0; i < IPREASS_NHASH; i++) { 1202 while(!TAILQ_EMPTY(&V_ipq[i])) { 1203 IPSTAT_ADD(ips_fragdropped, 1204 TAILQ_FIRST(&V_ipq[i])->ipq_nfrags); 1205 ip_freef(&V_ipq[i], TAILQ_FIRST(&V_ipq[i])); 1206 } 1207 } 1208} 1209 1210void 1211ip_drain(void) 1212{ 1213 VNET_ITERATOR_DECL(vnet_iter); 1214 1215 VNET_LIST_RLOCK_NOSLEEP(); 1216 IPQ_LOCK(); 1217 VNET_FOREACH(vnet_iter) { 1218 CURVNET_SET(vnet_iter); 1219 ip_drain_locked(); 1220 CURVNET_RESTORE(); 1221 } 1222 IPQ_UNLOCK(); 1223 VNET_LIST_RUNLOCK_NOSLEEP(); 1224 in_rtqdrain(); 1225} 1226 1227/* 1228 * The protocol to be inserted into ip_protox[] must be already registered 1229 * in inetsw[], either statically or through pf_proto_register(). 1230 */ 1231int 1232ipproto_register(short ipproto) 1233{ 1234 struct protosw *pr; 1235 1236 /* Sanity checks. */ 1237 if (ipproto <= 0 || ipproto >= IPPROTO_MAX) 1238 return (EPROTONOSUPPORT); 1239 1240 /* 1241 * The protocol slot must not be occupied by another protocol 1242 * already. An index pointing to IPPROTO_RAW is unused. 1243 */ 1244 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1245 if (pr == NULL) 1246 return (EPFNOSUPPORT); 1247 if (ip_protox[ipproto] != pr - inetsw) /* IPPROTO_RAW */ 1248 return (EEXIST); 1249 1250 /* Find the protocol position in inetsw[] and set the index. */ 1251 for (pr = inetdomain.dom_protosw; 1252 pr < inetdomain.dom_protoswNPROTOSW; pr++) { 1253 if (pr->pr_domain->dom_family == PF_INET && 1254 pr->pr_protocol && pr->pr_protocol == ipproto) { 1255 ip_protox[pr->pr_protocol] = pr - inetsw; 1256 return (0); 1257 } 1258 } 1259 return (EPROTONOSUPPORT); 1260} 1261 1262int 1263ipproto_unregister(short ipproto) 1264{ 1265 struct protosw *pr; 1266 1267 /* Sanity checks. */ 1268 if (ipproto <= 0 || ipproto >= IPPROTO_MAX) 1269 return (EPROTONOSUPPORT); 1270 1271 /* Check if the protocol was indeed registered. */ 1272 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 1273 if (pr == NULL) 1274 return (EPFNOSUPPORT); 1275 if (ip_protox[ipproto] == pr - inetsw) /* IPPROTO_RAW */ 1276 return (ENOENT); 1277 1278 /* Reset the protocol slot to IPPROTO_RAW. */ 1279 ip_protox[ipproto] = pr - inetsw; 1280 return (0); 1281} 1282 1283/* 1284 * Given address of next destination (final or next hop), return (referenced) 1285 * internet address info of interface to be used to get there. 1286 */ 1287struct in_ifaddr * 1288ip_rtaddr(struct in_addr dst, u_int fibnum) 1289{ 1290 struct route sro; 1291 struct sockaddr_in *sin; 1292 struct in_ifaddr *ia; 1293 1294 bzero(&sro, sizeof(sro)); 1295 sin = (struct sockaddr_in *)&sro.ro_dst; 1296 sin->sin_family = AF_INET; 1297 sin->sin_len = sizeof(*sin); 1298 sin->sin_addr = dst; 1299 in_rtalloc_ign(&sro, 0, fibnum); 1300 1301 if (sro.ro_rt == NULL) 1302 return (NULL); 1303 1304 ia = ifatoia(sro.ro_rt->rt_ifa); 1305 ifa_ref(&ia->ia_ifa); 1306 RTFREE(sro.ro_rt); 1307 return (ia); 1308} 1309 1310u_char inetctlerrmap[PRC_NCMDS] = { 1311 0, 0, 0, 0, 1312 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 1313 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 1314 EMSGSIZE, EHOSTUNREACH, 0, 0, 1315 0, 0, EHOSTUNREACH, 0, 1316 ENOPROTOOPT, ECONNREFUSED 1317}; 1318 1319/* 1320 * Forward a packet. If some error occurs return the sender 1321 * an icmp packet. Note we can't always generate a meaningful 1322 * icmp message because icmp doesn't have a large enough repertoire 1323 * of codes and types. 1324 * 1325 * If not forwarding, just drop the packet. This could be confusing 1326 * if ipforwarding was zero but some routing protocol was advancing 1327 * us as a gateway to somewhere. However, we must let the routing 1328 * protocol deal with that. 1329 * 1330 * The srcrt parameter indicates whether the packet is being forwarded 1331 * via a source route. 1332 */ 1333void 1334ip_forward(struct mbuf *m, int srcrt) 1335{ 1336 struct ip *ip = mtod(m, struct ip *); 1337 struct in_ifaddr *ia; 1338 struct mbuf *mcopy; 1339 struct in_addr dest; 1340 struct route ro; 1341 int error, type = 0, code = 0, mtu = 0; 1342 1343 if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) { 1344 IPSTAT_INC(ips_cantforward); 1345 m_freem(m); 1346 return; 1347 } 1348#ifdef IPSTEALTH 1349 if (!V_ipstealth) { 1350#endif 1351 if (ip->ip_ttl <= IPTTLDEC) { 1352 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 1353 0, 0); 1354 return; 1355 } 1356#ifdef IPSTEALTH 1357 } 1358#endif 1359 1360 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 1361#ifndef IPSEC 1362 /* 1363 * 'ia' may be NULL if there is no route for this destination. 1364 * In case of IPsec, Don't discard it just yet, but pass it to 1365 * ip_output in case of outgoing IPsec policy. 1366 */ 1367 if (!srcrt && ia == NULL) { 1368 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 1369 return; 1370 } 1371#endif 1372 1373 /* 1374 * Save the IP header and at most 8 bytes of the payload, 1375 * in case we need to generate an ICMP message to the src. 1376 * 1377 * XXX this can be optimized a lot by saving the data in a local 1378 * buffer on the stack (72 bytes at most), and only allocating the 1379 * mbuf if really necessary. The vast majority of the packets 1380 * are forwarded without having to send an ICMP back (either 1381 * because unnecessary, or because rate limited), so we are 1382 * really we are wasting a lot of work here. 1383 * 1384 * We don't use m_copy() because it might return a reference 1385 * to a shared cluster. Both this function and ip_output() 1386 * assume exclusive access to the IP header in `m', so any 1387 * data in a cluster may change before we reach icmp_error(). 1388 */ 1389 mcopy = m_gethdr(M_NOWAIT, m->m_type); 1390 if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_NOWAIT)) { 1391 /* 1392 * It's probably ok if the pkthdr dup fails (because 1393 * the deep copy of the tag chain failed), but for now 1394 * be conservative and just discard the copy since 1395 * code below may some day want the tags. 1396 */ 1397 m_free(mcopy); 1398 mcopy = NULL; 1399 } 1400 if (mcopy != NULL) { 1401 mcopy->m_len = min(ntohs(ip->ip_len), M_TRAILINGSPACE(mcopy)); 1402 mcopy->m_pkthdr.len = mcopy->m_len; 1403 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t)); 1404 } 1405 1406#ifdef IPSTEALTH 1407 if (!V_ipstealth) { 1408#endif 1409 ip->ip_ttl -= IPTTLDEC; 1410#ifdef IPSTEALTH 1411 } 1412#endif 1413 1414 /* 1415 * If forwarding packet using same interface that it came in on, 1416 * perhaps should send a redirect to sender to shortcut a hop. 1417 * Only send redirect if source is sending directly to us, 1418 * and if packet was not source routed (or has any options). 1419 * Also, don't send redirect if forwarding using a default route 1420 * or a route modified by a redirect. 1421 */ 1422 dest.s_addr = 0; 1423 if (!srcrt && V_ipsendredirects && 1424 ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) { 1425 struct sockaddr_in *sin; 1426 struct rtentry *rt; 1427 1428 bzero(&ro, sizeof(ro)); 1429 sin = (struct sockaddr_in *)&ro.ro_dst; 1430 sin->sin_family = AF_INET; 1431 sin->sin_len = sizeof(*sin); 1432 sin->sin_addr = ip->ip_dst; 1433 in_rtalloc_ign(&ro, 0, M_GETFIB(m)); 1434 1435 rt = ro.ro_rt; 1436 1437 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1438 satosin(rt_key(rt))->sin_addr.s_addr != 0) { 1439#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1440 u_long src = ntohl(ip->ip_src.s_addr); 1441 1442 if (RTA(rt) && 1443 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1444 if (rt->rt_flags & RTF_GATEWAY) 1445 dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr; 1446 else 1447 dest.s_addr = ip->ip_dst.s_addr; 1448 /* Router requirements says to only send host redirects */ 1449 type = ICMP_REDIRECT; 1450 code = ICMP_REDIRECT_HOST; 1451 } 1452 } 1453 if (rt) 1454 RTFREE(rt); 1455 } 1456 1457 /* 1458 * Try to cache the route MTU from ip_output so we can consider it for 1459 * the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191. 1460 */ 1461 bzero(&ro, sizeof(ro)); 1462 1463 error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL); 1464 1465 if (error == EMSGSIZE && ro.ro_rt)
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