sys/netinet/ip_input.c

   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  * $FreeBSD$
  31  */
  32
  33 #include "opt_bootp.h"
  34 #include "opt_ipfw.h"
  35 #include "opt_ipstealth.h"
  36 #include "opt_ipsec.h"
  37 #include "opt_mac.h"
  38 #include "opt_carp.h"
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/callout.h>
  43 #include <sys/mac.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/syslog.h>
  52 #include <sys/sysctl.h>
  53
  54 #include <net/pfil.h>
  55 #include <net/if.h>
  56 #include <net/if_types.h>
  57 #include <net/if_var.h>
  58 #include <net/if_dl.h>
  59 #include <net/route.h>
  60 #include <net/netisr.h>
  61
  62 #include <netinet/in.h>
  63 #include <netinet/in_systm.h>
  64 #include <netinet/in_var.h>
  65 #include <netinet/ip.h>
  66 #include <netinet/in_pcb.h>
  67 #include <netinet/ip_var.h>
  68 #include <netinet/ip_icmp.h>
  69 #include <machine/in_cksum.h>
  70 #ifdef DEV_CARP
  71 #include <netinet/ip_carp.h>
  72 #endif
  73
  74 #include <sys/socketvar.h>
  75
  76 /* XXX: Temporary until ipfw_ether and ipfw_bridge are converted. */
  77 #include <netinet/ip_fw.h>
  78 #include <netinet/ip_dummynet.h>
  79
  80 #ifdef IPSEC
  81 #include <netinet6/ipsec.h>
  82 #include <netkey/key.h>
  83 #endif
  84
  85 #ifdef FAST_IPSEC
  86 #include <netipsec/ipsec.h>
  87 #include <netipsec/key.h>
  88 #endif
  89
  90 int rsvp_on = 0;
  91
  92 int     ipforwarding = 0;
  93 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
  94     &ipforwarding, 0, "Enable IP forwarding between interfaces");
  95
  96 static int      ipsendredirects = 1; /* XXX */
  97 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
  98     &ipsendredirects, 0, "Enable sending IP redirects");
  99
 100 int     ip_defttl = IPDEFTTL;
 101 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
 102     &ip_defttl, 0, "Maximum TTL on IP packets");
 103
 104 static int      ip_dosourceroute = 0;
 105 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 106     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 107
 108 static int      ip_acceptsourceroute = 0;
 109 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 110     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 111     "Enable accepting source routed IP packets");
 112
 113 int             ip_doopts = 1;  /* 0 = ignore, 1 = process, 2 = reject */
 114 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
 115     &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
 116
 117 static int      ip_keepfaith = 0;
 118 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 119         &ip_keepfaith,  0,
 120         "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 121
 122 static int    nipq = 0;         /* total # of reass queues */
 123 static int    maxnipq;
 124 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 125         &maxnipq, 0,
 126         "Maximum number of IPv4 fragment reassembly queue entries");
 127
 128 static int    maxfragsperpacket;
 129 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 130         &maxfragsperpacket, 0,
 131         "Maximum number of IPv4 fragments allowed per packet");
 132
 133 static int      ip_sendsourcequench = 0;
 134 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 135         &ip_sendsourcequench, 0,
 136         "Enable the transmission of source quench packets");
 137
 138 int     ip_do_randomid = 0;
 139 SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
 140         &ip_do_randomid, 0,
 141         "Assign random ip_id values");
 142
 143 /*
 144  * XXX - Setting ip_checkinterface mostly implements the receive side of
 145  * the Strong ES model described in RFC 1122, but since the routing table
 146  * and transmit implementation do not implement the Strong ES model,
 147  * setting this to 1 results in an odd hybrid.
 148  *
 149  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 150  * to translate the destination address to another local interface.
 151  *
 152  * XXX - ip_checkinterface must be disabled if you add IP aliases
 153  * to the loopback interface instead of the interface where the
 154  * packets for those addresses are received.
 155  */
 156 static int      ip_checkinterface = 0;
 157 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 158     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 159
 160 #ifdef DIAGNOSTIC
 161 static int      ipprintfs = 0;
 162 #endif
 163
 164 struct pfil_head inet_pfil_hook;        /* Packet filter hooks */
 165
 166 static struct   ifqueue ipintrq;
 167 static int      ipqmaxlen = IFQ_MAXLEN;
 168
 169 extern  struct domain inetdomain;
 170 extern  struct protosw inetsw[];
 171 u_char  ip_protox[IPPROTO_MAX];
 172 struct  in_ifaddrhead in_ifaddrhead;            /* first inet address */
 173 struct  in_ifaddrhashhead *in_ifaddrhashtbl;    /* inet addr hash table  */
 174 u_long  in_ifaddrhmask;                         /* mask for hash table */
 175
 176 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 177     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 178 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 179     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 180
 181 struct ipstat ipstat;
 182 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 183     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
 184
 185 /* Packet reassembly stuff */
 186 #define IPREASS_NHASH_LOG2      6
 187 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 188 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 189 #define IPREASS_HASH(x,y) \
 190         (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 191
 192 static TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH];
 193 struct mtx ipqlock;
 194 struct callout ipport_tick_callout;
 195
 196 #define IPQ_LOCK()      mtx_lock(&ipqlock)
 197 #define IPQ_UNLOCK()    mtx_unlock(&ipqlock)
 198 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
 199 #define IPQ_LOCK_ASSERT()       mtx_assert(&ipqlock, MA_OWNED)
 200
 201 #ifdef IPCTL_DEFMTU
 202 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 203     &ip_mtu, 0, "Default MTU");
 204 #endif
 205
 206 #ifdef IPSTEALTH
 207 int     ipstealth = 0;
 208 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
 209     &ipstealth, 0, "");
 210 #endif
 211
 212 /*
 213  * ipfw_ether and ipfw_bridge hooks.
 214  * XXX: Temporary until those are converted to pfil_hooks as well.
 215  */
 216 ip_fw_chk_t *ip_fw_chk_ptr = NULL;
 217 ip_dn_io_t *ip_dn_io_ptr = NULL;
 218 int fw_enable = 1;
 219 int fw_one_pass = 1;
 220
 221 /*
 222  * XXX this is ugly.  IP options source routing magic.
 223  */
 224 struct ipoptrt {
 225         struct  in_addr dst;                    /* final destination */
 226         char    nop;                            /* one NOP to align */
 227         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 228         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 229 };
 230
 231 struct ipopt_tag {
 232         struct  m_tag tag;
 233         int     ip_nhops;
 234         struct  ipoptrt ip_srcrt;
 235 };
 236
 237 static void     save_rte(struct mbuf *, u_char *, struct in_addr);
 238 static int      ip_dooptions(struct mbuf *m, int);
 239 static void     ip_forward(struct mbuf *m, int srcrt);
 240 static void     ip_freef(struct ipqhead *, struct ipq *);
 241
 242 /*
 243  * IP initialization: fill in IP protocol switch table.
 244  * All protocols not implemented in kernel go to raw IP protocol handler.
 245  */
 246 void
 247 ip_init()
 248 {
 249         register struct protosw *pr;
 250         register int i;
 251
 252         TAILQ_INIT(&in_ifaddrhead);
 253         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 254         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 255         if (pr == NULL)
 256                 panic("ip_init: PF_INET not found");
 257
 258         /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
 259         for (i = 0; i < IPPROTO_MAX; i++)
 260                 ip_protox[i] = pr - inetsw;
 261         /*
 262          * Cycle through IP protocols and put them into the appropriate place
 263          * in ip_protox[].
 264          */
 265         for (pr = inetdomain.dom_protosw;
 266             pr < inetdomain.dom_protoswNPROTOSW; pr++)
 267                 if (pr->pr_domain->dom_family == PF_INET &&
 268                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
 269                         /* Be careful to only index valid IP protocols. */
 270                         if (pr->pr_protocol < IPPROTO_MAX)
 271                                 ip_protox[pr->pr_protocol] = pr - inetsw;
 272                 }
 273
 274         /* Initialize packet filter hooks. */
 275         inet_pfil_hook.ph_type = PFIL_TYPE_AF;
 276         inet_pfil_hook.ph_af = AF_INET;
 277         if ((i = pfil_head_register(&inet_pfil_hook)) != 0)
 278                 printf("%s: WARNING: unable to register pfil hook, "
 279                         "error %d\n", __func__, i);
 280
 281         /* Initialize IP reassembly queue. */
 282         IPQ_LOCK_INIT();
 283         for (i = 0; i < IPREASS_NHASH; i++)
 284             TAILQ_INIT(&ipq[i]);
 285         maxnipq = nmbclusters / 32;
 286         maxfragsperpacket = 16;
 287
 288         /* Start ipport_tick. */
 289         callout_init(&ipport_tick_callout, CALLOUT_MPSAFE);
 290         ipport_tick(NULL);
 291         EVENTHANDLER_REGISTER(shutdown_pre_sync, ip_fini, NULL,
 292                 SHUTDOWN_PRI_DEFAULT);
 293
 294         /* Initialize various other remaining things. */
 295         ip_id = time_second & 0xffff;
 296         ipintrq.ifq_maxlen = ipqmaxlen;
 297         mtx_init(&ipintrq.ifq_mtx, "ip_inq", NULL, MTX_DEF);
 298         netisr_register(NETISR_IP, ip_input, &ipintrq, NETISR_MPSAFE);
 299 }
 300
 301 void ip_fini(xtp)
 302         void *xtp;
 303 {
 304         callout_stop(&ipport_tick_callout);
 305 }
 306
 307 /*
 308  * Ip input routine.  Checksum and byte swap header.  If fragmented
 309  * try to reassemble.  Process options.  Pass to next level.
 310  */
 311 void
 312 ip_input(struct mbuf *m)
 313 {
 314         struct ip *ip = NULL;
 315         struct in_ifaddr *ia = NULL;
 316         struct ifaddr *ifa;
 317         int    checkif, hlen = 0;
 318         u_short sum;
 319         int dchg = 0;                           /* dest changed after fw */
 320         struct in_addr odst;                    /* original dst address */
 321 #ifdef FAST_IPSEC
 322         struct m_tag *mtag;
 323         struct tdb_ident *tdbi;
 324         struct secpolicy *sp;
 325         int s, error;
 326 #endif /* FAST_IPSEC */
 327
 328         M_ASSERTPKTHDR(m);
 329
 330         if (m->m_flags & M_FASTFWD_OURS) {
 331                 /*
 332                  * Firewall or NAT changed destination to local.
 333                  * We expect ip_len and ip_off to be in host byte order.
 334                  */
 335                 m->m_flags &= ~M_FASTFWD_OURS;
 336                 /* Set up some basics that will be used later. */
 337                 ip = mtod(m, struct ip *);
 338                 hlen = ip->ip_hl << 2;
 339                 goto ours;
 340         }
 341
 342         ipstat.ips_total++;
 343
 344         if (m->m_pkthdr.len < sizeof(struct ip))
 345                 goto tooshort;
 346
 347         if (m->m_len < sizeof (struct ip) &&
 348             (m = m_pullup(m, sizeof (struct ip))) == NULL) {
 349                 ipstat.ips_toosmall++;
 350                 return;
 351         }
 352         ip = mtod(m, struct ip *);
 353
 354         if (ip->ip_v != IPVERSION) {
 355                 ipstat.ips_badvers++;
 356                 goto bad;
 357         }
 358
 359         hlen = ip->ip_hl << 2;
 360         if (hlen < sizeof(struct ip)) { /* minimum header length */
 361                 ipstat.ips_badhlen++;
 362                 goto bad;
 363         }
 364         if (hlen > m->m_len) {
 365                 if ((m = m_pullup(m, hlen)) == NULL) {
 366                         ipstat.ips_badhlen++;
 367                         return;
 368                 }
 369                 ip = mtod(m, struct ip *);
 370         }
 371
 372         /* 127/8 must not appear on wire - RFC1122 */
 373         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 374             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 375                 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
 376                         ipstat.ips_badaddr++;
 377                         goto bad;
 378                 }
 379         }
 380
 381         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 382                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 383         } else {
 384                 if (hlen == sizeof(struct ip)) {
 385                         sum = in_cksum_hdr(ip);
 386                 } else {
 387                         sum = in_cksum(m, hlen);
 388                 }
 389         }
 390         if (sum) {
 391                 ipstat.ips_badsum++;
 392                 goto bad;
 393         }
 394
 395 #ifdef ALTQ
 396         if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
 397                 /* packet is dropped by traffic conditioner */
 398                 return;
 399 #endif
 400
 401         /*
 402          * Convert fields to host representation.
 403          */
 404         ip->ip_len = ntohs(ip->ip_len);
 405         if (ip->ip_len < hlen) {
 406                 ipstat.ips_badlen++;
 407                 goto bad;
 408         }
 409         ip->ip_off = ntohs(ip->ip_off);
 410
 411         /*
 412          * Check that the amount of data in the buffers
 413          * is as at least much as the IP header would have us expect.
 414          * Trim mbufs if longer than we expect.
 415          * Drop packet if shorter than we expect.
 416          */
 417         if (m->m_pkthdr.len < ip->ip_len) {
 418 tooshort:
 419                 ipstat.ips_tooshort++;
 420                 goto bad;
 421         }
 422         if (m->m_pkthdr.len > ip->ip_len) {
 423                 if (m->m_len == m->m_pkthdr.len) {
 424                         m->m_len = ip->ip_len;
 425                         m->m_pkthdr.len = ip->ip_len;
 426                 } else
 427                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 428         }
 429 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 430         /*
 431          * Bypass packet filtering for packets from a tunnel (gif).
 432          */
 433         if (ipsec_getnhist(m))
 434                 goto passin;
 435 #endif
 436 #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF)
 437         /*
 438          * Bypass packet filtering for packets from a tunnel (gif).
 439          */
 440         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 441                 goto passin;
 442 #endif
 443
 444         /*
 445          * Run through list of hooks for input packets.
 446          *
 447          * NB: Beware of the destination address changing (e.g.
 448          *     by NAT rewriting).  When this happens, tell
 449          *     ip_forward to do the right thing.
 450          */
 451
 452         /* Jump over all PFIL processing if hooks are not active. */
 453         if (inet_pfil_hook.ph_busy_count == -1)
 454                 goto passin;
 455
 456         odst = ip->ip_dst;
 457         if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
 458             PFIL_IN, NULL) != 0)
 459                 return;
 460         if (m == NULL)                  /* consumed by filter */
 461                 return;
 462
 463         ip = mtod(m, struct ip *);
 464         dchg = (odst.s_addr != ip->ip_dst.s_addr);
 465
 466 #ifdef IPFIREWALL_FORWARD
 467         if (m->m_flags & M_FASTFWD_OURS) {
 468                 m->m_flags &= ~M_FASTFWD_OURS;
 469                 goto ours;
 470         }
 471 #ifndef IPFIREWALL_FORWARD_EXTENDED
 472         dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
 473 #else
 474         if ((dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL)) != 0) {
 475                 /*
 476                  * Directly ship on the packet.  This allows to forward packets
 477                  * that were destined for us to some other directly connected
 478                  * host.
 479                  */
 480                 ip_forward(m, dchg);
 481                 return;
 482         }
 483 #endif /* IPFIREWALL_FORWARD_EXTENDED */
 484 #endif /* IPFIREWALL_FORWARD */
 485
 486 passin:
 487         /*
 488          * Process options and, if not destined for us,
 489          * ship it on.  ip_dooptions returns 1 when an
 490          * error was detected (causing an icmp message
 491          * to be sent and the original packet to be freed).
 492          */
 493         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
 494                 return;
 495
 496         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 497          * matter if it is destined to another node, or whether it is
 498          * a multicast one, RSVP wants it! and prevents it from being forwarded
 499          * anywhere else. Also checks if the rsvp daemon is running before
 500          * grabbing the packet.
 501          */
 502         if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
 503                 goto ours;
 504
 505         /*
 506          * Check our list of addresses, to see if the packet is for us.
 507          * If we don't have any addresses, assume any unicast packet
 508          * we receive might be for us (and let the upper layers deal
 509          * with it).
 510          */
 511         if (TAILQ_EMPTY(&in_ifaddrhead) &&
 512             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
 513                 goto ours;
 514
 515         /*
 516          * Enable a consistency check between the destination address
 517          * and the arrival interface for a unicast packet (the RFC 1122
 518          * strong ES model) if IP forwarding is disabled and the packet
 519          * is not locally generated and the packet is not subject to
 520          * 'ipfw fwd'.
 521          *
 522          * XXX - Checking also should be disabled if the destination
 523          * address is ipnat'ed to a different interface.
 524          *
 525          * XXX - Checking is incompatible with IP aliases added
 526          * to the loopback interface instead of the interface where
 527          * the packets are received.
 528          *
 529          * XXX - This is the case for carp vhost IPs as well so we
 530          * insert a workaround. If the packet got here, we already
 531          * checked with carp_iamatch() and carp_forus().
 532          */
 533         checkif = ip_checkinterface && (ipforwarding == 0) &&
 534             m->m_pkthdr.rcvif != NULL &&
 535             ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
 536 #ifdef DEV_CARP
 537             !m->m_pkthdr.rcvif->if_carp &&
 538 #endif
 539             (dchg == 0);
 540
 541         /*
 542          * Check for exact addresses in the hash bucket.
 543          */
 544         LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
 545                 /*
 546                  * If the address matches, verify that the packet
 547                  * arrived via the correct interface if checking is
 548                  * enabled.
 549                  */
 550                 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr &&
 551                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 552                         goto ours;
 553         }
 554         /*
 555          * Check for broadcast addresses.
 556          *
 557          * Only accept broadcast packets that arrive via the matching
 558          * interface.  Reception of forwarded directed broadcasts would
 559          * be handled via ip_forward() and ether_output() with the loopback
 560          * into the stack for SIMPLEX interfaces handled by ether_output().
 561          */
 562         if (m->m_pkthdr.rcvif != NULL &&
 563             m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 564                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 565                         if (ifa->ifa_addr->sa_family != AF_INET)
 566                                 continue;
 567                         ia = ifatoia(ifa);
 568                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 569                             ip->ip_dst.s_addr)
 570                                 goto ours;
 571                         if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
 572                                 goto ours;
 573 #ifdef BOOTP_COMPAT
 574                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 575                                 goto ours;
 576 #endif
 577                 }
 578         }
 579         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 580                 struct in_multi *inm;
 581                 if (ip_mrouter) {
 582                         /*
 583                          * If we are acting as a multicast router, all
 584                          * incoming multicast packets are passed to the
 585                          * kernel-level multicast forwarding function.
 586                          * The packet is returned (relatively) intact; if
 587                          * ip_mforward() returns a non-zero value, the packet
 588                          * must be discarded, else it may be accepted below.
 589                          */
 590                         if (ip_mforward &&
 591                             ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
 592                                 ipstat.ips_cantforward++;
 593                                 m_freem(m);
 594                                 return;
 595                         }
 596
 597                         /*
 598                          * The process-level routing daemon needs to receive
 599                          * all multicast IGMP packets, whether or not this
 600                          * host belongs to their destination groups.
 601                          */
 602                         if (ip->ip_p == IPPROTO_IGMP)
 603                                 goto ours;
 604                         ipstat.ips_forward++;
 605                 }
 606                 /*
 607                  * See if we belong to the destination multicast group on the
 608                  * arrival interface.
 609                  */
 610                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 611                 if (inm == NULL) {
 612                         ipstat.ips_notmember++;
 613                         m_freem(m);
 614                         return;
 615                 }
 616                 goto ours;
 617         }
 618         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 619                 goto ours;
 620         if (ip->ip_dst.s_addr == INADDR_ANY)
 621                 goto ours;
 622
 623         /*
 624          * FAITH(Firewall Aided Internet Translator)
 625          */
 626         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 627                 if (ip_keepfaith) {
 628                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 629                                 goto ours;
 630                 }
 631                 m_freem(m);
 632                 return;
 633         }
 634
 635         /*
 636          * Not for us; forward if possible and desirable.
 637          */
 638         if (ipforwarding == 0) {
 639                 ipstat.ips_cantforward++;
 640                 m_freem(m);
 641         } else {
 642 #ifdef IPSEC
 643                 /*
 644                  * Enforce inbound IPsec SPD.
 645                  */
 646                 if (ipsec4_in_reject(m, NULL)) {
 647                         ipsecstat.in_polvio++;
 648                         goto bad;
 649                 }
 650 #endif /* IPSEC */
 651 #ifdef FAST_IPSEC
 652                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 653                 s = splnet();
 654                 if (mtag != NULL) {
 655                         tdbi = (struct tdb_ident *)(mtag + 1);
 656                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 657                 } else {
 658                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 659                                                    IP_FORWARDING, &error);
 660                 }
 661                 if (sp == NULL) {       /* NB: can happen if error */
 662                         splx(s);
 663                         /*XXX error stat???*/
 664                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 665                         goto bad;
 666                 }
 667
 668                 /*
 669                  * Check security policy against packet attributes.
 670                  */
 671                 error = ipsec_in_reject(sp, m);
 672                 KEY_FREESP(&sp);
 673                 splx(s);
 674                 if (error) {
 675                         ipstat.ips_cantforward++;
 676                         goto bad;
 677                 }
 678 #endif /* FAST_IPSEC */
 679                 ip_forward(m, dchg);
 680         }
 681         return;
 682
 683 ours:
 684 #ifdef IPSTEALTH
 685         /*
 686          * IPSTEALTH: Process non-routing options only
 687          * if the packet is destined for us.
 688          */
 689         if (ipstealth && hlen > sizeof (struct ip) &&
 690             ip_dooptions(m, 1))
 691                 return;
 692 #endif /* IPSTEALTH */
 693
 694         /* Count the packet in the ip address stats */
 695         if (ia != NULL) {
 696                 ia->ia_ifa.if_ipackets++;
 697                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 698         }
 699
 700         /*
 701          * Attempt reassembly; if it succeeds, proceed.
 702          * ip_reass() will return a different mbuf.
 703          */
 704         if (ip->ip_off & (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         /*
 714          * Further protocols expect the packet length to be w/o the
 715          * IP header.
 716          */
 717         ip->ip_len -= hlen;
 718
 719 #ifdef IPSEC
 720         /*
 721          * enforce IPsec policy checking if we are seeing last header.
 722          * note that we do not visit this with protocols with pcb layer
 723          * code - like udp/tcp/raw ip.
 724          */
 725         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 726             ipsec4_in_reject(m, NULL)) {
 727                 ipsecstat.in_polvio++;
 728                 goto bad;
 729         }
 730 #endif
 731 #if FAST_IPSEC
 732         /*
 733          * enforce IPsec policy checking if we are seeing last header.
 734          * note that we do not visit this with protocols with pcb layer
 735          * code - like udp/tcp/raw ip.
 736          */
 737         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 738                 /*
 739                  * Check if the packet has already had IPsec processing
 740                  * done.  If so, then just pass it along.  This tag gets
 741                  * set during AH, ESP, etc. input handling, before the
 742                  * packet is returned to the ip input queue for delivery.
 743                  */
 744                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 745                 s = splnet();
 746                 if (mtag != NULL) {
 747                         tdbi = (struct tdb_ident *)(mtag + 1);
 748                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 749                 } else {
 750                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 751                                                    IP_FORWARDING, &error);
 752                 }
 753                 if (sp != NULL) {
 754                         /*
 755                          * Check security policy against packet attributes.
 756                          */
 757                         error = ipsec_in_reject(sp, m);
 758                         KEY_FREESP(&sp);
 759                 } else {
 760                         /* XXX error stat??? */
 761                         error = EINVAL;
 762 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 763                         goto bad;
 764                 }
 765                 splx(s);
 766                 if (error)
 767                         goto bad;
 768         }
 769 #endif /* FAST_IPSEC */
 770
 771         /*
 772          * Switch out to protocol's input routine.
 773          */
 774         ipstat.ips_delivered++;
 775
 776         (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
 777         return;
 778 bad:
 779         m_freem(m);
 780 }
 781
 782 /*
 783  * Take incoming datagram fragment and try to reassemble it into
 784  * whole datagram.  If the argument is the first fragment or one
 785  * in between the function will return NULL and store the mbuf
 786  * in the fragment chain.  If the argument is the last fragment
 787  * the packet will be reassembled and the pointer to the new
 788  * mbuf returned for further processing.  Only m_tags attached
 789  * to the first packet/fragment are preserved.
 790  * The IP header is *NOT* adjusted out of iplen.
 791  */
 792
 793 struct mbuf *
 794 ip_reass(struct mbuf *m)
 795 {
 796         struct ip *ip;
 797         struct mbuf *p, *q, *nq, *t;
 798         struct ipq *fp = NULL;
 799         struct ipqhead *head;
 800         int i, hlen, next;
 801         u_int8_t ecn, ecn0;
 802         u_short hash;
 803
 804         /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
 805         if (maxnipq == 0 || maxfragsperpacket == 0) {
 806                 ipstat.ips_fragments++;
 807                 ipstat.ips_fragdropped++;
 808                 m_freem(m);
 809                 return (NULL);
 810         }
 811
 812         ip = mtod(m, struct ip *);
 813         hlen = ip->ip_hl << 2;
 814
 815         hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 816         head = &ipq[hash];
 817         IPQ_LOCK();
 818
 819         /*
 820          * Look for queue of fragments
 821          * of this datagram.
 822          */
 823         TAILQ_FOREACH(fp, head, ipq_list)
 824                 if (ip->ip_id == fp->ipq_id &&
 825                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 826                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 827 #ifdef MAC
 828                     mac_fragment_match(m, fp) &&
 829 #endif
 830                     ip->ip_p == fp->ipq_p)
 831                         goto found;
 832
 833         fp = NULL;
 834
 835         /*
 836          * Enforce upper bound on number of fragmented packets
 837          * for which we attempt reassembly;
 838          * If maxnipq is -1, accept all fragments without limitation.
 839          */
 840         if ((nipq > maxnipq) && (maxnipq > 0)) {
 841                 /*
 842                  * drop something from the tail of the current queue
 843                  * before proceeding further
 844                  */
 845                 struct ipq *q = TAILQ_LAST(head, ipqhead);
 846                 if (q == NULL) {   /* gak */
 847                         for (i = 0; i < IPREASS_NHASH; i++) {
 848                                 struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead);
 849                                 if (r) {
 850                                         ipstat.ips_fragtimeout += r->ipq_nfrags;
 851                                         ip_freef(&ipq[i], r);
 852                                         break;
 853                                 }
 854                         }
 855                 } else {
 856                         ipstat.ips_fragtimeout += q->ipq_nfrags;
 857                         ip_freef(head, q);
 858                 }
 859         }
 860
 861 found:
 862         /*
 863          * Adjust ip_len to not reflect header,
 864          * convert offset of this to bytes.
 865          */
 866         ip->ip_len -= hlen;
 867         if (ip->ip_off & IP_MF) {
 868                 /*
 869                  * Make sure that fragments have a data length
 870                  * that's a non-zero multiple of 8 bytes.
 871                  */
 872                 if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 873                         ipstat.ips_toosmall++; /* XXX */
 874                         goto dropfrag;
 875                 }
 876                 m->m_flags |= M_FRAG;
 877         } else
 878                 m->m_flags &= ~M_FRAG;
 879         ip->ip_off <<= 3;
 880
 881
 882         /*
 883          * Attempt reassembly; if it succeeds, proceed.
 884          * ip_reass() will return a different mbuf.
 885          */
 886         ipstat.ips_fragments++;
 887         m->m_pkthdr.header = ip;
 888
 889         /* Previous ip_reass() started here. */
 890         /*
 891          * Presence of header sizes in mbufs
 892          * would confuse code below.
 893          */
 894         m->m_data += hlen;
 895         m->m_len -= hlen;
 896
 897         /*
 898          * If first fragment to arrive, create a reassembly queue.
 899          */
 900         if (fp == NULL) {
 901                 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
 902                         goto dropfrag;
 903                 fp = mtod(t, struct ipq *);
 904 #ifdef MAC
 905                 if (mac_init_ipq(fp, M_NOWAIT) != 0) {
 906                         m_free(t);
 907                         goto dropfrag;
 908                 }
 909                 mac_create_ipq(m, fp);
 910 #endif
 911                 TAILQ_INSERT_HEAD(head, fp, ipq_list);
 912                 nipq++;
 913                 fp->ipq_nfrags = 1;
 914                 fp->ipq_ttl = IPFRAGTTL;
 915                 fp->ipq_p = ip->ip_p;
 916                 fp->ipq_id = ip->ip_id;
 917                 fp->ipq_src = ip->ip_src;
 918                 fp->ipq_dst = ip->ip_dst;
 919                 fp->ipq_frags = m;
 920                 m->m_nextpkt = NULL;
 921                 goto done;
 922         } else {
 923                 fp->ipq_nfrags++;
 924 #ifdef MAC
 925                 mac_update_ipq(m, fp);
 926 #endif
 927         }
 928
 929 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
 930
 931         /*
 932          * Handle ECN by comparing this segment with the first one;
 933          * if CE is set, do not lose CE.
 934          * drop if CE and not-ECT are mixed for the same packet.
 935          */
 936         ecn = ip->ip_tos & IPTOS_ECN_MASK;
 937         ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
 938         if (ecn == IPTOS_ECN_CE) {
 939                 if (ecn0 == IPTOS_ECN_NOTECT)
 940                         goto dropfrag;
 941                 if (ecn0 != IPTOS_ECN_CE)
 942                         GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
 943         }
 944         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
 945                 goto dropfrag;
 946
 947         /*
 948          * Find a segment which begins after this one does.
 949          */
 950         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
 951                 if (GETIP(q)->ip_off > ip->ip_off)
 952                         break;
 953
 954         /*
 955          * If there is a preceding segment, it may provide some of
 956          * our data already.  If so, drop the data from the incoming
 957          * segment.  If it provides all of our data, drop us, otherwise
 958          * stick new segment in the proper place.
 959          *
 960          * If some of the data is dropped from the the preceding
 961          * segment, then it's checksum is invalidated.
 962          */
 963         if (p) {
 964                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
 965                 if (i > 0) {
 966                         if (i >= ip->ip_len)
 967                                 goto dropfrag;
 968                         m_adj(m, i);
 969                         m->m_pkthdr.csum_flags = 0;
 970                         ip->ip_off += i;
 971                         ip->ip_len -= i;
 972                 }
 973                 m->m_nextpkt = p->m_nextpkt;
 974                 p->m_nextpkt = m;
 975         } else {
 976                 m->m_nextpkt = fp->ipq_frags;
 977                 fp->ipq_frags = m;
 978         }
 979
 980         /*
 981          * While we overlap succeeding segments trim them or,
 982          * if they are completely covered, dequeue them.
 983          */
 984         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
 985              q = nq) {
 986                 i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
 987                 if (i < GETIP(q)->ip_len) {
 988                         GETIP(q)->ip_len -= i;
 989                         GETIP(q)->ip_off += i;
 990                         m_adj(q, i);
 991                         q->m_pkthdr.csum_flags = 0;
 992                         break;
 993                 }
 994                 nq = q->m_nextpkt;
 995                 m->m_nextpkt = nq;
 996                 ipstat.ips_fragdropped++;
 997                 fp->ipq_nfrags--;
 998                 m_freem(q);
 999         }
1000
1001         /*
1002          * Check for complete reassembly and perform frag per packet
1003          * limiting.
1004          *
1005          * Frag limiting is performed here so that the nth frag has
1006          * a chance to complete the packet before we drop the packet.
1007          * As a result, n+1 frags are actually allowed per packet, but
1008          * only n will ever be stored. (n = maxfragsperpacket.)
1009          *
1010          */
1011         next = 0;
1012         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
1013                 if (GETIP(q)->ip_off != next) {
1014                         if (fp->ipq_nfrags > maxfragsperpacket) {
1015                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1016                                 ip_freef(head, fp);
1017                         }
1018                         goto done;
1019                 }
1020                 next += GETIP(q)->ip_len;
1021         }
1022         /* Make sure the last packet didn't have the IP_MF flag */
1023         if (p->m_flags & M_FRAG) {
1024                 if (fp->ipq_nfrags > maxfragsperpacket) {
1025                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1026                         ip_freef(head, fp);
1027                 }
1028                 goto done;
1029         }
1030
1031         /*
1032          * Reassembly is complete.  Make sure the packet is a sane size.
1033          */
1034         q = fp->ipq_frags;
1035         ip = GETIP(q);
1036         if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
1037                 ipstat.ips_toolong++;
1038                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1039                 ip_freef(head, fp);
1040                 goto done;
1041         }
1042
1043         /*
1044          * Concatenate fragments.
1045          */
1046         m = q;
1047         t = m->m_next;
1048         m->m_next = NULL;
1049         m_cat(m, t);
1050         nq = q->m_nextpkt;
1051         q->m_nextpkt = NULL;
1052         for (q = nq; q != NULL; q = nq) {
1053                 nq = q->m_nextpkt;
1054                 q->m_nextpkt = NULL;
1055                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1056                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1057                 m_cat(m, q);
1058         }
1059 #ifdef MAC
1060         mac_create_datagram_from_ipq(fp, m);
1061         mac_destroy_ipq(fp);
1062 #endif
1063
1064         /*
1065          * Create header for new ip packet by modifying header of first
1066          * packet;  dequeue and discard fragment reassembly header.
1067          * Make header visible.
1068          */
1069         ip->ip_len = (ip->ip_hl << 2) + next;
1070         ip->ip_src = fp->ipq_src;
1071         ip->ip_dst = fp->ipq_dst;
1072         TAILQ_REMOVE(head, fp, ipq_list);
1073         nipq--;
1074         (void) m_free(dtom(fp));
1075         m->m_len += (ip->ip_hl << 2);
1076         m->m_data -= (ip->ip_hl << 2);
1077         /* some debugging cruft by sklower, below, will go away soon */
1078         if (m->m_flags & M_PKTHDR)      /* XXX this should be done elsewhere */
1079                 m_fixhdr(m);
1080         ipstat.ips_reassembled++;
1081         IPQ_UNLOCK();
1082         return (m);
1083
1084 dropfrag:
1085         ipstat.ips_fragdropped++;
1086         if (fp != NULL)
1087                 fp->ipq_nfrags--;
1088         m_freem(m);
1089 done:
1090         IPQ_UNLOCK();
1091         return (NULL);
1092
1093 #undef GETIP
1094 }
1095
1096 /*
1097  * Free a fragment reassembly header and all
1098  * associated datagrams.
1099  */
1100 static void
1101 ip_freef(fhp, fp)
1102         struct ipqhead *fhp;
1103         struct ipq *fp;
1104 {
1105         register struct mbuf *q;
1106
1107         IPQ_LOCK_ASSERT();
1108
1109         while (fp->ipq_frags) {
1110                 q = fp->ipq_frags;
1111                 fp->ipq_frags = q->m_nextpkt;
1112                 m_freem(q);
1113         }
1114         TAILQ_REMOVE(fhp, fp, ipq_list);
1115         (void) m_free(dtom(fp));
1116         nipq--;
1117 }
1118
1119 /*
1120  * IP timer processing;
1121  * if a timer expires on a reassembly
1122  * queue, discard it.
1123  */
1124 void
1125 ip_slowtimo()
1126 {
1127         register struct ipq *fp;
1128         int s = splnet();
1129         int i;
1130
1131         IPQ_LOCK();
1132         for (i = 0; i < IPREASS_NHASH; i++) {
1133                 for(fp = TAILQ_FIRST(&ipq[i]); fp;) {
1134                         struct ipq *fpp;
1135
1136                         fpp = fp;
1137                         fp = TAILQ_NEXT(fp, ipq_list);
1138                         if(--fpp->ipq_ttl == 0) {
1139                                 ipstat.ips_fragtimeout += fpp->ipq_nfrags;
1140                                 ip_freef(&ipq[i], fpp);
1141                         }
1142                 }
1143         }
1144         /*
1145          * If we are over the maximum number of fragments
1146          * (due to the limit being lowered), drain off
1147          * enough to get down to the new limit.
1148          */
1149         if (maxnipq >= 0 && nipq > maxnipq) {
1150                 for (i = 0; i < IPREASS_NHASH; i++) {
1151                         while (nipq > maxnipq && !TAILQ_EMPTY(&ipq[i])) {
1152                                 ipstat.ips_fragdropped +=
1153                                     TAILQ_FIRST(&ipq[i])->ipq_nfrags;
1154                                 ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1155                         }
1156                 }
1157         }
1158         IPQ_UNLOCK();
1159         splx(s);
1160 }
1161
1162 /*
1163  * Drain off all datagram fragments.
1164  */
1165 void
1166 ip_drain()
1167 {
1168         int     i;
1169
1170         IPQ_LOCK();
1171         for (i = 0; i < IPREASS_NHASH; i++) {
1172                 while(!TAILQ_EMPTY(&ipq[i])) {
1173                         ipstat.ips_fragdropped +=
1174                             TAILQ_FIRST(&ipq[i])->ipq_nfrags;
1175                         ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1176                 }
1177         }
1178         IPQ_UNLOCK();
1179         in_rtqdrain();
1180 }
1181
1182 /*
1183  * The protocol to be inserted into ip_protox[] must be already registered
1184  * in inetsw[], either statically or through pf_proto_register().
1185  */
1186 int
1187 ipproto_register(u_char ipproto)
1188 {
1189         struct protosw *pr;
1190
1191         /* Sanity checks. */
1192         if (ipproto == 0)
1193                 return (EPROTONOSUPPORT);
1194
1195         /*
1196          * The protocol slot must not be occupied by another protocol
1197          * already.  An index pointing to IPPROTO_RAW is unused.
1198          */
1199         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
1200         if (pr == NULL)
1201                 return (EPFNOSUPPORT);
1202         if (ip_protox[ipproto] != pr - inetsw)  /* IPPROTO_RAW */
1203                 return (EEXIST);
1204
1205         /* Find the protocol position in inetsw[] and set the index. */
1206         for (pr = inetdomain.dom_protosw;
1207              pr < inetdomain.dom_protoswNPROTOSW; pr++) {
1208                 if (pr->pr_domain->dom_family == PF_INET &&
1209                     pr->pr_protocol && pr->pr_protocol == ipproto) {
1210                         /* Be careful to only index valid IP protocols. */
1211                         if (pr->pr_protocol < IPPROTO_MAX) {
1212                                 ip_protox[pr->pr_protocol] = pr - inetsw;
1213                                 return (0);
1214                         } else
1215                                 return (EINVAL);
1216                 }
1217         }
1218         return (EPROTONOSUPPORT);
1219 }
1220
1221 int
1222 ipproto_unregister(u_char ipproto)
1223 {
1224         struct protosw *pr;
1225
1226         /* Sanity checks. */
1227         if (ipproto == 0)
1228                 return (EPROTONOSUPPORT);
1229
1230         /* Check if the protocol was indeed registered. */
1231         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
1232         if (pr == NULL)
1233                 return (EPFNOSUPPORT);
1234         if (ip_protox[ipproto] == pr - inetsw)  /* IPPROTO_RAW */
1235                 return (ENOENT);
1236
1237         /* Reset the protocol slot to IPPROTO_RAW. */
1238         ip_protox[ipproto] = pr - inetsw;
1239         return (0);
1240 }
1241
1242
1243 /*
1244  * Do option processing on a datagram,
1245  * possibly discarding it if bad options are encountered,
1246  * or forwarding it if source-routed.
1247  * The pass argument is used when operating in the IPSTEALTH
1248  * mode to tell what options to process:
1249  * [LS]SRR (pass 0) or the others (pass 1).
1250  * The reason for as many as two passes is that when doing IPSTEALTH,
1251  * non-routing options should be processed only if the packet is for us.
1252  * Returns 1 if packet has been forwarded/freed,
1253  * 0 if the packet should be processed further.
1254  */
1255 static int
1256 ip_dooptions(struct mbuf *m, int pass)
1257 {
1258         struct ip *ip = mtod(m, struct ip *);
1259         u_char *cp;
1260         struct in_ifaddr *ia;
1261         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1262         struct in_addr *sin, dst;
1263         n_time ntime;
1264         struct  sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
1265
1266         /* ignore or reject packets with IP options */
1267         if (ip_doopts == 0)
1268                 return 0;
1269         else if (ip_doopts == 2) {
1270                 type = ICMP_UNREACH;
1271                 code = ICMP_UNREACH_FILTER_PROHIB;
1272                 goto bad;
1273         }
1274
1275         dst = ip->ip_dst;
1276         cp = (u_char *)(ip + 1);
1277         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
1278         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1279                 opt = cp[IPOPT_OPTVAL];
1280                 if (opt == IPOPT_EOL)
1281                         break;
1282                 if (opt == IPOPT_NOP)
1283                         optlen = 1;
1284                 else {
1285                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1286                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1287                                 goto bad;
1288                         }
1289                         optlen = cp[IPOPT_OLEN];
1290                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1291                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1292                                 goto bad;
1293                         }
1294                 }
1295                 switch (opt) {
1296
1297                 default:
1298                         break;
1299
1300                 /*
1301                  * Source routing with record.
1302                  * Find interface with current destination address.
1303                  * If none on this machine then drop if strictly routed,
1304                  * or do nothing if loosely routed.
1305                  * Record interface address and bring up next address
1306                  * component.  If strictly routed make sure next
1307                  * address is on directly accessible net.
1308                  */
1309                 case IPOPT_LSRR:
1310                 case IPOPT_SSRR:
1311 #ifdef IPSTEALTH
1312                         if (ipstealth && pass > 0)
1313                                 break;
1314 #endif
1315                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1316                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1317                                 goto bad;
1318                         }
1319                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1320                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1321                                 goto bad;
1322                         }
1323                         ipaddr.sin_addr = ip->ip_dst;
1324                         ia = (struct in_ifaddr *)
1325                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1326                         if (ia == NULL) {
1327                                 if (opt == IPOPT_SSRR) {
1328                                         type = ICMP_UNREACH;
1329                                         code = ICMP_UNREACH_SRCFAIL;
1330                                         goto bad;
1331                                 }
1332                                 if (!ip_dosourceroute)
1333                                         goto nosourcerouting;
1334                                 /*
1335                                  * Loose routing, and not at next destination
1336                                  * yet; nothing to do except forward.
1337                                  */
1338                                 break;
1339                         }
1340                         off--;                  /* 0 origin */
1341                         if (off > optlen - (int)sizeof(struct in_addr)) {
1342                                 /*
1343                                  * End of source route.  Should be for us.
1344                                  */
1345                                 if (!ip_acceptsourceroute)
1346                                         goto nosourcerouting;
1347                                 save_rte(m, cp, ip->ip_src);
1348                                 break;
1349                         }
1350 #ifdef IPSTEALTH
1351                         if (ipstealth)
1352                                 goto dropit;
1353 #endif
1354                         if (!ip_dosourceroute) {
1355                                 if (ipforwarding) {
1356                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1357                                         /*
1358                                          * Acting as a router, so generate ICMP
1359                                          */
1360 nosourcerouting:
1361                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1362                                         log(LOG_WARNING,
1363                                             "attempted source route from %s to %s\n",
1364                                             inet_ntoa(ip->ip_src), buf);
1365                                         type = ICMP_UNREACH;
1366                                         code = ICMP_UNREACH_SRCFAIL;
1367                                         goto bad;
1368                                 } else {
1369                                         /*
1370                                          * Not acting as a router, so silently drop.
1371                                          */
1372 #ifdef IPSTEALTH
1373 dropit:
1374 #endif
1375                                         ipstat.ips_cantforward++;
1376                                         m_freem(m);
1377                                         return (1);
1378                                 }
1379                         }
1380
1381                         /*
1382                          * locate outgoing interface
1383                          */
1384                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1385                             sizeof(ipaddr.sin_addr));
1386
1387                         if (opt == IPOPT_SSRR) {
1388 #define INA     struct in_ifaddr *
1389 #define SA      struct sockaddr *
1390                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
1391                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1392                         } else
1393                                 ia = ip_rtaddr(ipaddr.sin_addr);
1394                         if (ia == NULL) {
1395                                 type = ICMP_UNREACH;
1396                                 code = ICMP_UNREACH_SRCFAIL;
1397                                 goto bad;
1398                         }
1399                         ip->ip_dst = ipaddr.sin_addr;
1400                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1401                             sizeof(struct in_addr));
1402                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1403                         /*
1404                          * Let ip_intr's mcast routing check handle mcast pkts
1405                          */
1406                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1407                         break;
1408
1409                 case IPOPT_RR:
1410 #ifdef IPSTEALTH
1411                         if (ipstealth && pass == 0)
1412                                 break;
1413 #endif
1414                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1415                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1416                                 goto bad;
1417                         }
1418                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1419                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1420                                 goto bad;
1421                         }
1422                         /*
1423                          * If no space remains, ignore.
1424                          */
1425                         off--;                  /* 0 origin */
1426                         if (off > optlen - (int)sizeof(struct in_addr))
1427                                 break;
1428                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1429                             sizeof(ipaddr.sin_addr));
1430                         /*
1431                          * locate outgoing interface; if we're the destination,
1432                          * use the incoming interface (should be same).
1433                          */
1434                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
1435                             (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
1436                                 type = ICMP_UNREACH;
1437                                 code = ICMP_UNREACH_HOST;
1438                                 goto bad;
1439                         }
1440                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1441                             sizeof(struct in_addr));
1442                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1443                         break;
1444
1445                 case IPOPT_TS:
1446 #ifdef IPSTEALTH
1447                         if (ipstealth && pass == 0)
1448                                 break;
1449 #endif
1450                         code = cp - (u_char *)ip;
1451                         if (optlen < 4 || optlen > 40) {
1452                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1453                                 goto bad;
1454                         }
1455                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1456                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1457                                 goto bad;
1458                         }
1459                         if (off > optlen - (int)sizeof(int32_t)) {
1460                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1461                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1462                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1463                                         goto bad;
1464                                 }
1465                                 break;
1466                         }
1467                         off--;                          /* 0 origin */
1468                         sin = (struct in_addr *)(cp + off);
1469                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1470
1471                         case IPOPT_TS_TSONLY:
1472                                 break;
1473
1474                         case IPOPT_TS_TSANDADDR:
1475                                 if (off + sizeof(n_time) +
1476                                     sizeof(struct in_addr) > optlen) {
1477                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1478                                         goto bad;
1479                                 }
1480                                 ipaddr.sin_addr = dst;
1481                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1482                                                             m->m_pkthdr.rcvif);
1483                                 if (ia == NULL)
1484                                         continue;
1485                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1486                                     sizeof(struct in_addr));
1487                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1488                                 off += sizeof(struct in_addr);
1489                                 break;
1490
1491                         case IPOPT_TS_PRESPEC:
1492                                 if (off + sizeof(n_time) +
1493                                     sizeof(struct in_addr) > optlen) {
1494                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1495                                         goto bad;
1496                                 }
1497                                 (void)memcpy(&ipaddr.sin_addr, sin,
1498                                     sizeof(struct in_addr));
1499                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
1500                                         continue;
1501                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1502                                 off += sizeof(struct in_addr);
1503                                 break;
1504
1505                         default:
1506                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1507                                 goto bad;
1508                         }
1509                         ntime = iptime();
1510                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1511                         cp[IPOPT_OFFSET] += sizeof(n_time);
1512                 }
1513         }
1514         if (forward && ipforwarding) {
1515                 ip_forward(m, 1);
1516                 return (1);
1517         }
1518         return (0);
1519 bad:
1520         icmp_error(m, type, code, 0, 0);
1521         ipstat.ips_badoptions++;
1522         return (1);
1523 }
1524
1525 /*
1526  * Given address of next destination (final or next hop),
1527  * return internet address info of interface to be used to get there.
1528  */
1529 struct in_ifaddr *
1530 ip_rtaddr(dst)
1531         struct in_addr dst;
1532 {
1533         struct route sro;
1534         struct sockaddr_in *sin;
1535         struct in_ifaddr *ifa;
1536
1537         bzero(&sro, sizeof(sro));
1538         sin = (struct sockaddr_in *)&sro.ro_dst;
1539         sin->sin_family = AF_INET;
1540         sin->sin_len = sizeof(*sin);
1541         sin->sin_addr = dst;
1542         rtalloc_ign(&sro, RTF_CLONING);
1543
1544         if (sro.ro_rt == NULL)
1545                 return (NULL);
1546
1547         ifa = ifatoia(sro.ro_rt->rt_ifa);
1548         RTFREE(sro.ro_rt);
1549         return (ifa);
1550 }
1551
1552 /*
1553  * Save incoming source route for use in replies,
1554  * to be picked up later by ip_srcroute if the receiver is interested.
1555  */
1556 static void
1557 save_rte(m, option, dst)
1558         struct mbuf *m;
1559         u_char *option;
1560         struct in_addr dst;
1561 {
1562         unsigned olen;
1563         struct ipopt_tag *opts;
1564
1565         opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
1566                                         sizeof(struct ipopt_tag), M_NOWAIT);
1567         if (opts == NULL)
1568                 return;
1569
1570         olen = option[IPOPT_OLEN];
1571 #ifdef DIAGNOSTIC
1572         if (ipprintfs)
1573                 printf("save_rte: olen %d\n", olen);
1574 #endif
1575         if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
1576                 m_tag_free((struct m_tag *)opts);
1577                 return;
1578         }
1579         bcopy(option, opts->ip_srcrt.srcopt, olen);
1580         opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1581         opts->ip_srcrt.dst = dst;
1582         m_tag_prepend(m, (struct m_tag *)opts);
1583 }
1584
1585 /*
1586  * Retrieve incoming source route for use in replies,
1587  * in the same form used by setsockopt.
1588  * The first hop is placed before the options, will be removed later.
1589  */
1590 struct mbuf *
1591 ip_srcroute(m0)
1592         struct mbuf *m0;
1593 {
1594         register struct in_addr *p, *q;
1595         register struct mbuf *m;
1596         struct ipopt_tag *opts;
1597
1598         opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
1599         if (opts == NULL)
1600                 return (NULL);
1601
1602         if (opts->ip_nhops == 0)
1603                 return (NULL);
1604         m = m_get(M_DONTWAIT, MT_HEADER);
1605         if (m == NULL)
1606                 return (NULL);
1607
1608 #define OPTSIZ  (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
1609
1610         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1611         m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
1612             sizeof(struct in_addr) + OPTSIZ;
1613 #ifdef DIAGNOSTIC
1614         if (ipprintfs)
1615                 printf("ip_srcroute: nhops %d mlen %d", opts->ip_nhops, m->m_len);
1616 #endif
1617
1618         /*
1619          * First save first hop for return route
1620          */
1621         p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
1622         *(mtod(m, struct in_addr *)) = *p--;
1623 #ifdef DIAGNOSTIC
1624         if (ipprintfs)
1625                 printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1626 #endif
1627
1628         /*
1629          * Copy option fields and padding (nop) to mbuf.
1630          */
1631         opts->ip_srcrt.nop = IPOPT_NOP;
1632         opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1633         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1634             &(opts->ip_srcrt.nop), OPTSIZ);
1635         q = (struct in_addr *)(mtod(m, caddr_t) +
1636             sizeof(struct in_addr) + OPTSIZ);
1637 #undef OPTSIZ
1638         /*
1639          * Record return path as an IP source route,
1640          * reversing the path (pointers are now aligned).
1641          */
1642         while (p >= opts->ip_srcrt.route) {
1643 #ifdef DIAGNOSTIC
1644                 if (ipprintfs)
1645                         printf(" %lx", (u_long)ntohl(q->s_addr));
1646 #endif
1647                 *q++ = *p--;
1648         }
1649         /*
1650          * Last hop goes to final destination.
1651          */
1652         *q = opts->ip_srcrt.dst;
1653 #ifdef DIAGNOSTIC
1654         if (ipprintfs)
1655                 printf(" %lx\n", (u_long)ntohl(q->s_addr));
1656 #endif
1657         m_tag_delete(m0, (struct m_tag *)opts);
1658         return (m);
1659 }
1660
1661 /*
1662  * Strip out IP options, at higher
1663  * level protocol in the kernel.
1664  * Second argument is buffer to which options
1665  * will be moved, and return value is their length.
1666  * XXX should be deleted; last arg currently ignored.
1667  */
1668 void
1669 ip_stripoptions(m, mopt)
1670         register struct mbuf *m;
1671         struct mbuf *mopt;
1672 {
1673         register int i;
1674         struct ip *ip = mtod(m, struct ip *);
1675         register caddr_t opts;
1676         int olen;
1677
1678         olen = (ip->ip_hl << 2) - sizeof (struct ip);
1679         opts = (caddr_t)(ip + 1);
1680         i = m->m_len - (sizeof (struct ip) + olen);
1681         bcopy(opts + olen, opts, (unsigned)i);
1682         m->m_len -= olen;
1683         if (m->m_flags & M_PKTHDR)
1684                 m->m_pkthdr.len -= olen;
1685         ip->ip_v = IPVERSION;
1686         ip->ip_hl = sizeof(struct ip) >> 2;
1687 }
1688
1689 u_char inetctlerrmap[PRC_NCMDS] = {
1690         0,              0,              0,              0,
1691         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1692         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1693         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1694         0,              0,              EHOSTUNREACH,   0,
1695         ENOPROTOOPT,    ECONNREFUSED
1696 };
1697
1698 /*
1699  * Forward a packet.  If some error occurs return the sender
1700  * an icmp packet.  Note we can't always generate a meaningful
1701  * icmp message because icmp doesn't have a large enough repertoire
1702  * of codes and types.
1703  *
1704  * If not forwarding, just drop the packet.  This could be confusing
1705  * if ipforwarding was zero but some routing protocol was advancing
1706  * us as a gateway to somewhere.  However, we must let the routing
1707  * protocol deal with that.
1708  *
1709  * The srcrt parameter indicates whether the packet is being forwarded
1710  * via a source route.
1711  */
1712 void
1713 ip_forward(struct mbuf *m, int srcrt)
1714 {
1715         struct ip *ip = mtod(m, struct ip *);
1716         struct in_ifaddr *ia = NULL;
1717         struct mbuf *mcopy;
1718         struct in_addr dest;
1719         int error, type = 0, code = 0, mtu = 0;
1720
1721 #ifdef DIAGNOSTIC
1722         if (ipprintfs)
1723                 printf("forward: src %lx dst %lx ttl %x\n",
1724                     (u_long)ip->ip_src.s_addr, (u_long)ip->ip_dst.s_addr,
1725                     ip->ip_ttl);
1726 #endif
1727
1728
1729         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
1730                 ipstat.ips_cantforward++;
1731                 m_freem(m);
1732                 return;
1733         }
1734 #ifdef IPSTEALTH
1735         if (!ipstealth) {
1736 #endif
1737                 if (ip->ip_ttl <= IPTTLDEC) {
1738                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1739                             0, 0);
1740                         return;
1741                 }
1742 #ifdef IPSTEALTH
1743         }
1744 #endif
1745
1746         if (!srcrt && (ia = ip_rtaddr(ip->ip_dst)) == NULL) {
1747                 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
1748                 return;
1749         }
1750
1751         /*
1752          * Save the IP header and at most 8 bytes of the payload,
1753          * in case we need to generate an ICMP message to the src.
1754          *
1755          * XXX this can be optimized a lot by saving the data in a local
1756          * buffer on the stack (72 bytes at most), and only allocating the
1757          * mbuf if really necessary. The vast majority of the packets
1758          * are forwarded without having to send an ICMP back (either
1759          * because unnecessary, or because rate limited), so we are
1760          * really we are wasting a lot of work here.
1761          *
1762          * We don't use m_copy() because it might return a reference
1763          * to a shared cluster. Both this function and ip_output()
1764          * assume exclusive access to the IP header in `m', so any
1765          * data in a cluster may change before we reach icmp_error().
1766          */
1767         MGET(mcopy, M_DONTWAIT, m->m_type);
1768         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
1769                 /*
1770                  * It's probably ok if the pkthdr dup fails (because
1771                  * the deep copy of the tag chain failed), but for now
1772                  * be conservative and just discard the copy since
1773                  * code below may some day want the tags.
1774                  */
1775                 m_free(mcopy);
1776                 mcopy = NULL;
1777         }
1778         if (mcopy != NULL) {
1779                 mcopy->m_len = imin((ip->ip_hl << 2) + 8,
1780                     (int)ip->ip_len);
1781                 mcopy->m_pkthdr.len = mcopy->m_len;
1782                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1783         }
1784
1785 #ifdef IPSTEALTH
1786         if (!ipstealth) {
1787 #endif
1788                 ip->ip_ttl -= IPTTLDEC;
1789 #ifdef IPSTEALTH
1790         }
1791 #endif
1792
1793         /*
1794          * If forwarding packet using same interface that it came in on,
1795          * perhaps should send a redirect to sender to shortcut a hop.
1796          * Only send redirect if source is sending directly to us,
1797          * and if packet was not source routed (or has any options).
1798          * Also, don't send redirect if forwarding using a default route
1799          * or a route modified by a redirect.
1800          */
1801         dest.s_addr = 0;
1802         if (!srcrt && ipsendredirects && ia->ia_ifp == m->m_pkthdr.rcvif) {
1803                 struct sockaddr_in *sin;
1804                 struct route ro;
1805                 struct rtentry *rt;
1806
1807                 bzero(&ro, sizeof(ro));
1808                 sin = (struct sockaddr_in *)&ro.ro_dst;
1809                 sin->sin_family = AF_INET;
1810                 sin->sin_len = sizeof(*sin);
1811                 sin->sin_addr = ip->ip_dst;
1812                 rtalloc_ign(&ro, RTF_CLONING);
1813
1814                 rt = ro.ro_rt;
1815
1816                 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1817                     satosin(rt_key(rt))->sin_addr.s_addr != 0) {
1818 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1819                         u_long src = ntohl(ip->ip_src.s_addr);
1820
1821                         if (RTA(rt) &&
1822                             (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1823                                 if (rt->rt_flags & RTF_GATEWAY)
1824                                         dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
1825                                 else
1826                                         dest.s_addr = ip->ip_dst.s_addr;
1827                                 /* Router requirements says to only send host redirects */
1828                                 type = ICMP_REDIRECT;
1829                                 code = ICMP_REDIRECT_HOST;
1830 #ifdef DIAGNOSTIC
1831                                 if (ipprintfs)
1832                                         printf("redirect (%d) to %lx\n", code, (u_long)dest.s_addr);
1833 #endif
1834                         }
1835                 }
1836                 if (rt)
1837                         RTFREE(rt);
1838         }
1839
1840         error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
1841         if (error)
1842                 ipstat.ips_cantforward++;
1843         else {
1844                 ipstat.ips_forward++;
1845                 if (type)
1846                         ipstat.ips_redirectsent++;
1847                 else {
1848                         if (mcopy)
1849                                 m_freem(mcopy);
1850                         return;
1851                 }
1852         }
1853         if (mcopy == NULL)
1854                 return;
1855
1856         switch (error) {
1857
1858         case 0:                         /* forwarded, but need redirect */
1859                 /* type, code set above */
1860                 break;
1861
1862         case ENETUNREACH:               /* shouldn't happen, checked above */
1863         case EHOSTUNREACH:
1864         case ENETDOWN:
1865         case EHOSTDOWN:
1866         default:
1867                 type = ICMP_UNREACH;
1868                 code = ICMP_UNREACH_HOST;
1869                 break;
1870
1871         case EMSGSIZE:
1872                 type = ICMP_UNREACH;
1873                 code = ICMP_UNREACH_NEEDFRAG;
1874 #if defined(IPSEC) || defined(FAST_IPSEC)
1875                 /*
1876                  * If the packet is routed over IPsec tunnel, tell the
1877                  * originator the tunnel MTU.
1878                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1879                  * XXX quickhack!!!
1880                  */
1881                 {
1882                         struct secpolicy *sp = NULL;
1883                         int ipsecerror;
1884                         int ipsechdr;
1885                         struct route *ro;
1886
1887 #ifdef IPSEC
1888                         sp = ipsec4_getpolicybyaddr(mcopy,
1889                                                     IPSEC_DIR_OUTBOUND,
1890                                                     IP_FORWARDING,
1891                                                     &ipsecerror);
1892 #else /* FAST_IPSEC */
1893                         sp = ipsec_getpolicybyaddr(mcopy,
1894                                                    IPSEC_DIR_OUTBOUND,
1895                                                    IP_FORWARDING,
1896                                                    &ipsecerror);
1897 #endif
1898                         if (sp != NULL) {
1899                                 /* count IPsec header size */
1900                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1901                                                          IPSEC_DIR_OUTBOUND,
1902                                                          NULL);
1903
1904                                 /*
1905                                  * find the correct route for outer IPv4
1906                                  * header, compute tunnel MTU.
1907                                  */
1908                                 if (sp->req != NULL
1909                                  && sp->req->sav != NULL
1910                                  && sp->req->sav->sah != NULL) {
1911                                         ro = &sp->req->sav->sah->sa_route;
1912                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1913                                                 mtu =
1914                                                     ro->ro_rt->rt_rmx.rmx_mtu ?
1915                                                     ro->ro_rt->rt_rmx.rmx_mtu :
1916                                                     ro->ro_rt->rt_ifp->if_mtu;
1917                                                 mtu -= ipsechdr;
1918                                         }
1919                                 }
1920
1921 #ifdef IPSEC
1922                                 key_freesp(sp);
1923 #else /* FAST_IPSEC */
1924                                 KEY_FREESP(&sp);
1925 #endif
1926                                 ipstat.ips_cantfrag++;
1927                                 break;
1928                         } else
1929 #endif /*IPSEC || FAST_IPSEC*/
1930                 /*
1931                  * When doing source routing 'ia' can be NULL.  Fall back
1932                  * to the minimum guaranteed routeable packet size and use
1933                  * the same hack as IPSEC to setup a dummyifp for icmp.
1934                  */
1935                 if (ia == NULL)
1936                         mtu = IP_MSS;
1937                 else
1938                         mtu = ia->ia_ifp->if_mtu;
1939 #if defined(IPSEC) || defined(FAST_IPSEC)
1940                 }
1941 #endif /*IPSEC || FAST_IPSEC*/
1942                 ipstat.ips_cantfrag++;
1943                 break;
1944
1945         case ENOBUFS:
1946                 /*
1947                  * A router should not generate ICMP_SOURCEQUENCH as
1948                  * required in RFC1812 Requirements for IP Version 4 Routers.
1949                  * Source quench could be a big problem under DoS attacks,
1950                  * or if the underlying interface is rate-limited.
1951                  * Those who need source quench packets may re-enable them
1952                  * via the net.inet.ip.sendsourcequench sysctl.
1953                  */
1954                 if (ip_sendsourcequench == 0) {
1955                         m_freem(mcopy);
1956                         return;
1957                 } else {
1958                         type = ICMP_SOURCEQUENCH;
1959                         code = 0;
1960                 }
1961                 break;
1962
1963         case EACCES:                    /* ipfw denied packet */
1964                 m_freem(mcopy);
1965                 return;
1966         }
1967         icmp_error(mcopy, type, code, dest.s_addr, mtu);
1968 }
1969
1970 void
1971 ip_savecontrol(inp, mp, ip, m)
1972         register struct inpcb *inp;
1973         register struct mbuf **mp;
1974         register struct ip *ip;
1975         register struct mbuf *m;
1976 {
1977         if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
1978                 struct bintime bt;
1979
1980                 bintime(&bt);
1981                 if (inp->inp_socket->so_options & SO_BINTIME) {
1982                         *mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt),
1983                         SCM_BINTIME, SOL_SOCKET);
1984                         if (*mp)
1985                                 mp = &(*mp)->m_next;
1986                 }
1987                 if (inp->inp_socket->so_options & SO_TIMESTAMP) {
1988                         struct timeval tv;
1989
1990                         bintime2timeval(&bt, &tv);
1991                         *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
1992                                 SCM_TIMESTAMP, SOL_SOCKET);
1993                         if (*mp)
1994                                 mp = &(*mp)->m_next;
1995                 }
1996         }
1997         if (inp->inp_flags & INP_RECVDSTADDR) {
1998                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
1999                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
2000                 if (*mp)
2001                         mp = &(*mp)->m_next;
2002         }
2003         if (inp->inp_flags & INP_RECVTTL) {
2004                 *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
2005                     sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
2006                 if (*mp)
2007                         mp = &(*mp)->m_next;
2008         }
2009 #ifdef notyet
2010         /* XXX
2011          * Moving these out of udp_input() made them even more broken
2012          * than they already were.
2013          */
2014         /* options were tossed already */
2015         if (inp->inp_flags & INP_RECVOPTS) {
2016                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2017                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2018                 if (*mp)
2019                         mp = &(*mp)->m_next;
2020         }
2021         /* ip_srcroute doesn't do what we want here, need to fix */
2022         if (inp->inp_flags & INP_RECVRETOPTS) {
2023                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(m),
2024                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2025                 if (*mp)
2026                         mp = &(*mp)->m_next;
2027         }
2028 #endif
2029         if (inp->inp_flags & INP_RECVIF) {
2030                 struct ifnet *ifp;
2031                 struct sdlbuf {
2032                         struct sockaddr_dl sdl;
2033                         u_char  pad[32];
2034                 } sdlbuf;
2035                 struct sockaddr_dl *sdp;
2036                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2037
2038                 if (((ifp = m->m_pkthdr.rcvif))
2039                 && ( ifp->if_index && (ifp->if_index <= if_index))) {
2040                         sdp = (struct sockaddr_dl *)
2041                             (ifaddr_byindex(ifp->if_index)->ifa_addr);
2042                         /*
2043                          * Change our mind and don't try copy.
2044                          */
2045                         if ((sdp->sdl_family != AF_LINK)
2046                         || (sdp->sdl_len > sizeof(sdlbuf))) {
2047                                 goto makedummy;
2048                         }
2049                         bcopy(sdp, sdl2, sdp->sdl_len);
2050                 } else {
2051 makedummy:
2052                         sdl2->sdl_len
2053                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
2054                         sdl2->sdl_family = AF_LINK;
2055                         sdl2->sdl_index = 0;
2056                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2057                 }
2058                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2059                         IP_RECVIF, IPPROTO_IP);
2060                 if (*mp)
2061                         mp = &(*mp)->m_next;
2062         }
2063 }
2064
2065 /*
2066  * XXX these routines are called from the upper part of the kernel.
2067  * They need to be locked when we remove Giant.
2068  *
2069  * They could also be moved to ip_mroute.c, since all the RSVP
2070  *  handling is done there already.
2071  */
2072 static int ip_rsvp_on;
2073 struct socket *ip_rsvpd;
2074 int
2075 ip_rsvp_init(struct socket *so)
2076 {
2077         if (so->so_type != SOCK_RAW ||
2078             so->so_proto->pr_protocol != IPPROTO_RSVP)
2079                 return EOPNOTSUPP;
2080
2081         if (ip_rsvpd != NULL)
2082                 return EADDRINUSE;
2083
2084         ip_rsvpd = so;
2085         /*
2086          * This may seem silly, but we need to be sure we don't over-increment
2087          * the RSVP counter, in case something slips up.
2088          */
2089         if (!ip_rsvp_on) {
2090                 ip_rsvp_on = 1;
2091                 rsvp_on++;
2092         }
2093
2094         return 0;
2095 }
2096
2097 int
2098 ip_rsvp_done(void)
2099 {
2100         ip_rsvpd = NULL;
2101         /*
2102          * This may seem silly, but we need to be sure we don't over-decrement
2103          * the RSVP counter, in case something slips up.
2104          */
2105         if (ip_rsvp_on) {
2106                 ip_rsvp_on = 0;
2107                 rsvp_on--;
2108         }
2109         return 0;
2110 }
2111
2112 void
2113 rsvp_input(struct mbuf *m, int off)     /* XXX must fixup manually */
2114 {
2115         if (rsvp_input_p) { /* call the real one if loaded */
2116                 rsvp_input_p(m, off);
2117                 return;
2118         }
2119
2120         /* Can still get packets with rsvp_on = 0 if there is a local member
2121          * of the group to which the RSVP packet is addressed.  But in this
2122          * case we want to throw the packet away.
2123          */
2124
2125         if (!rsvp_on) {
2126                 m_freem(m);
2127                 return;
2128         }
2129
2130         if (ip_rsvpd != NULL) {
2131                 rip_input(m, off);
2132                 return;
2133         }
2134         /* Drop the packet */
2135         m_freem(m);
2136 }