sys/net/ipfw/ip_fw2.c

   1 /*
   2  * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/sys/netinet/ip_fw2.c,v 1.6.2.12 2003/04/08 10:42:32 maxim Exp $
  26  * $DragonFly: src/sys/net/ipfw/ip_fw2.c,v 1.59 2008/07/31 14:39:36 sephe Exp $
  27  */
  28
  29 #define        DEB(x)
  30 #define        DDB(x) x
  31
  32 /*
  33  * Implement IP packet firewall (new version)
  34  */
  35
  36 #ifndef KLD_MODULE
  37 #include "opt_ipfw.h"
  38 #include "opt_ipdn.h"
  39 #include "opt_ipdivert.h"
  40 #include "opt_inet.h"
  41 #ifndef INET
  42 #error IPFIREWALL requires INET.
  43 #endif /* INET */
  44 #endif
  45
  46 #include <sys/param.h>
  47 #include <sys/systm.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mbuf.h>
  50 #include <sys/kernel.h>
  51 #include <sys/proc.h>
  52 #include <sys/socket.h>
  53 #include <sys/socketvar.h>
  54 #include <sys/sysctl.h>
  55 #include <sys/syslog.h>
  56 #include <sys/thread2.h>
  57 #include <sys/ucred.h>
  58 #include <sys/in_cksum.h>
  59
  60 #include <net/if.h>
  61 #include <net/route.h>
  62 #include <net/netmsg2.h>
  63
  64 #include <netinet/in.h>
  65 #include <netinet/in_systm.h>
  66 #include <netinet/in_var.h>
  67 #include <netinet/in_pcb.h>
  68 #include <netinet/ip.h>
  69 #include <netinet/ip_var.h>
  70 #include <netinet/ip_icmp.h>
  71 #include "ip_fw.h"
  72 #include <net/dummynet/ip_dummynet.h>
  73 #include <netinet/tcp.h>
  74 #include <netinet/tcp_timer.h>
  75 #include <netinet/tcp_var.h>
  76 #include <netinet/tcpip.h>
  77 #include <netinet/udp.h>
  78 #include <netinet/udp_var.h>
  79
  80 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */
  81
  82 /*
  83  * set_disable contains one bit per set value (0..31).
  84  * If the bit is set, all rules with the corresponding set
  85  * are disabled. Set 31 is reserved for the default rule
  86  * and CANNOT be disabled.
  87  */
  88 static uint32_t set_disable;
  89
  90 static int fw_verbose;
  91 static int verbose_limit;
  92
  93 #ifdef KLD_MODULE
  94 static int ipfw_refcnt;
  95 #endif
  96
  97 static struct callout ipfw_timeout_h;
  98 #define IPFW_DEFAULT_RULE       65535
  99
 100 /*
 101  * list of rules for layer 3
 102  */
 103 static struct ip_fw *layer3_chain;
 104
 105 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");
 106
 107 static int fw_debug = 1;
 108 static int autoinc_step = 100; /* bounded to 1..1000 in ipfw_add_rule() */
 109
 110 #ifdef SYSCTL_NODE
 111 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
 112 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW,
 113     &fw_enable, 0, "Enable ipfw");
 114 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW,
 115     &autoinc_step, 0, "Rule number autincrement step");
 116 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW,
 117     &fw_one_pass, 0,
 118     "Only do a single pass through ipfw when using dummynet(4)");
 119 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW,
 120     &fw_debug, 0, "Enable printing of debug ip_fw statements");
 121 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW,
 122     &fw_verbose, 0, "Log matches to ipfw rules");
 123 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW,
 124     &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged");
 125
 126 /*
 127  * Description of dynamic rules.
 128  *
 129  * Dynamic rules are stored in lists accessed through a hash table
 130  * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
 131  * be modified through the sysctl variable dyn_buckets which is
 132  * updated when the table becomes empty.
 133  *
 134  * XXX currently there is only one list, ipfw_dyn.
 135  *
 136  * When a packet is received, its address fields are first masked
 137  * with the mask defined for the rule, then hashed, then matched
 138  * against the entries in the corresponding list.
 139  * Dynamic rules can be used for different purposes:
 140  *  + stateful rules;
 141  *  + enforcing limits on the number of sessions;
 142  *  + in-kernel NAT (not implemented yet)
 143  *
 144  * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
 145  * measured in seconds and depending on the flags.
 146  *
 147  * The total number of dynamic rules is stored in dyn_count.
 148  * The max number of dynamic rules is dyn_max. When we reach
 149  * the maximum number of rules we do not create anymore. This is
 150  * done to avoid consuming too much memory, but also too much
 151  * time when searching on each packet (ideally, we should try instead
 152  * to put a limit on the length of the list on each bucket...).
 153  *
 154  * Each dynamic rule holds a pointer to the parent ipfw rule so
 155  * we know what action to perform. Dynamic rules are removed when
 156  * the parent rule is deleted. XXX we should make them survive.
 157  *
 158  * There are some limitations with dynamic rules -- we do not
 159  * obey the 'randomized match', and we do not do multiple
 160  * passes through the firewall. XXX check the latter!!!
 161  */
 162 static ipfw_dyn_rule **ipfw_dyn_v = NULL;
 163 static uint32_t dyn_buckets = 256; /* must be power of 2 */
 164 static uint32_t curr_dyn_buckets = 256; /* must be power of 2 */
 165
 166 /*
 167  * Timeouts for various events in handing dynamic rules.
 168  */
 169 static uint32_t dyn_ack_lifetime = 300;
 170 static uint32_t dyn_syn_lifetime = 20;
 171 static uint32_t dyn_fin_lifetime = 1;
 172 static uint32_t dyn_rst_lifetime = 1;
 173 static uint32_t dyn_udp_lifetime = 10;
 174 static uint32_t dyn_short_lifetime = 5;
 175
 176 /*
 177  * Keepalives are sent if dyn_keepalive is set. They are sent every
 178  * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
 179  * seconds of lifetime of a rule.
 180  * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
 181  * than dyn_keepalive_period.
 182  */
 183
 184 static uint32_t dyn_keepalive_interval = 20;
 185 static uint32_t dyn_keepalive_period = 5;
 186 static uint32_t dyn_keepalive = 1;      /* do send keepalives */
 187
 188 static uint32_t static_count;           /* # of static rules */
 189 static uint32_t static_ioc_len; /* bytes of static rules */
 190 static uint32_t dyn_count;              /* # of dynamic rules */
 191 static uint32_t dyn_max = 4096; /* max # of dynamic rules */
 192
 193 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW,
 194     &dyn_buckets, 0, "Number of dyn. buckets");
 195 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD,
 196     &curr_dyn_buckets, 0, "Current Number of dyn. buckets");
 197 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD,
 198     &dyn_count, 0, "Number of dyn. rules");
 199 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW,
 200     &dyn_max, 0, "Max number of dyn. rules");
 201 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD,
 202     &static_count, 0, "Number of static rules");
 203 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW,
 204     &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks");
 205 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW,
 206     &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn");
 207 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW,
 208     &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin");
 209 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW,
 210     &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst");
 211 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW,
 212     &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP");
 213 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW,
 214     &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations");
 215 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW,
 216     &dyn_keepalive, 0, "Enable keepalives for dyn. rules");
 217
 218 #endif /* SYSCTL_NODE */
 219
 220 static struct ip_fw *ip_fw_default_rule;
 221
 222 static ip_fw_chk_t      ipfw_chk;
 223
 224 static __inline int
 225 ipfw_free_rule(struct ip_fw *rule)
 226 {
 227         KASSERT(rule->refcnt > 0, ("invalid refcnt %u\n", rule->refcnt));
 228         atomic_subtract_int(&rule->refcnt, 1);
 229         if (atomic_cmpset_int(&rule->refcnt, 0, 1)) {
 230                 kfree(rule, M_IPFW);
 231                 return 1;
 232         }
 233         return 0;
 234 }
 235
 236 static void
 237 ipfw_unref_rule(void *priv)
 238 {
 239         ipfw_free_rule(priv);
 240 #ifdef KLD_MODULE
 241         atomic_subtract_int(&ipfw_refcnt, 1);
 242 #endif
 243 }
 244
 245 static __inline void
 246 ipfw_ref_rule(struct ip_fw *rule)
 247 {
 248 #ifdef KLD_MODULE
 249         atomic_add_int(&ipfw_refcnt, 1);
 250 #endif
 251         atomic_add_int(&rule->refcnt, 1);
 252 }
 253
 254 /*
 255  * This macro maps an ip pointer into a layer3 header pointer of type T
 256  */
 257 #define L3HDR(T, ip) ((T *)((uint32_t *)(ip) + (ip)->ip_hl))
 258
 259 static __inline int
 260 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd)
 261 {
 262         int type = L3HDR(struct icmp,ip)->icmp_type;
 263
 264         return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1 << type)));
 265 }
 266
 267 #define TT      ((1 << ICMP_ECHO) | \
 268                  (1 << ICMP_ROUTERSOLICIT) | \
 269                  (1 << ICMP_TSTAMP) | \
 270                  (1 << ICMP_IREQ) | \
 271                  (1 << ICMP_MASKREQ))
 272
 273 static int
 274 is_icmp_query(struct ip *ip)
 275 {
 276         int type = L3HDR(struct icmp, ip)->icmp_type;
 277
 278         return (type <= ICMP_MAXTYPE && (TT & (1 << type)));
 279 }
 280
 281 #undef TT
 282
 283 /*
 284  * The following checks use two arrays of 8 or 16 bits to store the
 285  * bits that we want set or clear, respectively. They are in the
 286  * low and high half of cmd->arg1 or cmd->d[0].
 287  *
 288  * We scan options and store the bits we find set. We succeed if
 289  *
 290  *      (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear
 291  *
 292  * The code is sometimes optimized not to store additional variables.
 293  */
 294
 295 static int
 296 flags_match(ipfw_insn *cmd, uint8_t bits)
 297 {
 298         u_char want_clear;
 299         bits = ~bits;
 300
 301         if (((cmd->arg1 & 0xff) & bits) != 0)
 302                 return 0; /* some bits we want set were clear */
 303
 304         want_clear = (cmd->arg1 >> 8) & 0xff;
 305         if ((want_clear & bits) != want_clear)
 306                 return 0; /* some bits we want clear were set */
 307         return 1;
 308 }
 309
 310 static int
 311 ipopts_match(struct ip *ip, ipfw_insn *cmd)
 312 {
 313         int optlen, bits = 0;
 314         u_char *cp = (u_char *)(ip + 1);
 315         int x = (ip->ip_hl << 2) - sizeof(struct ip);
 316
 317         for (; x > 0; x -= optlen, cp += optlen) {
 318                 int opt = cp[IPOPT_OPTVAL];
 319
 320                 if (opt == IPOPT_EOL)
 321                         break;
 322
 323                 if (opt == IPOPT_NOP) {
 324                         optlen = 1;
 325                 } else {
 326                         optlen = cp[IPOPT_OLEN];
 327                         if (optlen <= 0 || optlen > x)
 328                                 return 0; /* invalid or truncated */
 329                 }
 330
 331                 switch (opt) {
 332                 case IPOPT_LSRR:
 333                         bits |= IP_FW_IPOPT_LSRR;
 334                         break;
 335
 336                 case IPOPT_SSRR:
 337                         bits |= IP_FW_IPOPT_SSRR;
 338                         break;
 339
 340                 case IPOPT_RR:
 341                         bits |= IP_FW_IPOPT_RR;
 342                         break;
 343
 344                 case IPOPT_TS:
 345                         bits |= IP_FW_IPOPT_TS;
 346                         break;
 347
 348                 default:
 349                         break;
 350                 }
 351         }
 352         return (flags_match(cmd, bits));
 353 }
 354
 355 static int
 356 tcpopts_match(struct ip *ip, ipfw_insn *cmd)
 357 {
 358         int optlen, bits = 0;
 359         struct tcphdr *tcp = L3HDR(struct tcphdr,ip);
 360         u_char *cp = (u_char *)(tcp + 1);
 361         int x = (tcp->th_off << 2) - sizeof(struct tcphdr);
 362
 363         for (; x > 0; x -= optlen, cp += optlen) {
 364                 int opt = cp[0];
 365
 366                 if (opt == TCPOPT_EOL)
 367                         break;
 368
 369                 if (opt == TCPOPT_NOP) {
 370                         optlen = 1;
 371                 } else {
 372                         optlen = cp[1];
 373                         if (optlen <= 0)
 374                                 break;
 375                 }
 376
 377                 switch (opt) {
 378                 case TCPOPT_MAXSEG:
 379                         bits |= IP_FW_TCPOPT_MSS;
 380                         break;
 381
 382                 case TCPOPT_WINDOW:
 383                         bits |= IP_FW_TCPOPT_WINDOW;
 384                         break;
 385
 386                 case TCPOPT_SACK_PERMITTED:
 387                 case TCPOPT_SACK:
 388                         bits |= IP_FW_TCPOPT_SACK;
 389                         break;
 390
 391                 case TCPOPT_TIMESTAMP:
 392                         bits |= IP_FW_TCPOPT_TS;
 393                         break;
 394
 395                 case TCPOPT_CC:
 396                 case TCPOPT_CCNEW:
 397                 case TCPOPT_CCECHO:
 398                         bits |= IP_FW_TCPOPT_CC;
 399                         break;
 400
 401                 default:
 402                         break;
 403                 }
 404         }
 405         return (flags_match(cmd, bits));
 406 }
 407
 408 static int
 409 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd)
 410 {
 411         if (ifp == NULL)        /* no iface with this packet, match fails */
 412                 return 0;
 413
 414         /* Check by name or by IP address */
 415         if (cmd->name[0] != '\0') { /* match by name */
 416                 /* Check name */
 417                 if (cmd->p.glob) {
 418                         if (kfnmatch(cmd->name, ifp->if_xname, 0) == 0)
 419                                 return(1);
 420                 } else {
 421                         if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0)
 422                                 return(1);
 423                 }
 424         } else {
 425                 struct ifaddr_container *ifac;
 426
 427                 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 428                         struct ifaddr *ia = ifac->ifa;
 429
 430                         if (ia->ifa_addr == NULL)
 431                                 continue;
 432                         if (ia->ifa_addr->sa_family != AF_INET)
 433                                 continue;
 434                         if (cmd->p.ip.s_addr == ((struct sockaddr_in *)
 435                             (ia->ifa_addr))->sin_addr.s_addr)
 436                                 return(1);      /* match */
 437                 }
 438         }
 439         return(0);      /* no match, fail ... */
 440 }
 441
 442 static uint64_t norule_counter; /* counter for ipfw_log(NULL...) */
 443
 444 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0
 445
 446 /*
 447  * We enter here when we have a rule with O_LOG.
 448  * XXX this function alone takes about 2Kbytes of code!
 449  */
 450 static void
 451 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh,
 452          struct mbuf *m, struct ifnet *oif)
 453 {
 454         char *action;
 455         int limit_reached = 0;
 456         char action2[40], proto[48], fragment[28];
 457
 458         fragment[0] = '\0';
 459         proto[0] = '\0';
 460
 461         if (f == NULL) {        /* bogus pkt */
 462                 if (verbose_limit != 0 && norule_counter >= verbose_limit)
 463                         return;
 464                 norule_counter++;
 465                 if (norule_counter == verbose_limit)
 466                         limit_reached = verbose_limit;
 467                 action = "Refuse";
 468         } else {        /* O_LOG is the first action, find the real one */
 469                 ipfw_insn *cmd = ACTION_PTR(f);
 470                 ipfw_insn_log *l = (ipfw_insn_log *)cmd;
 471
 472                 if (l->max_log != 0 && l->log_left == 0)
 473                         return;
 474                 l->log_left--;
 475                 if (l->log_left == 0)
 476                         limit_reached = l->max_log;
 477                 cmd += F_LEN(cmd);      /* point to first action */
 478                 if (cmd->opcode == O_PROB)
 479                         cmd += F_LEN(cmd);
 480
 481                 action = action2;
 482                 switch (cmd->opcode) {
 483                 case O_DENY:
 484                         action = "Deny";
 485                         break;
 486
 487                 case O_REJECT:
 488                         if (cmd->arg1==ICMP_REJECT_RST) {
 489                                 action = "Reset";
 490                         } else if (cmd->arg1==ICMP_UNREACH_HOST) {
 491                                 action = "Reject";
 492                         } else {
 493                                 ksnprintf(SNPARGS(action2, 0), "Unreach %d",
 494                                           cmd->arg1);
 495                         }
 496                         break;
 497
 498                 case O_ACCEPT:
 499                         action = "Accept";
 500                         break;
 501
 502                 case O_COUNT:
 503                         action = "Count";
 504                         break;
 505
 506                 case O_DIVERT:
 507                         ksnprintf(SNPARGS(action2, 0), "Divert %d", cmd->arg1);
 508                         break;
 509
 510                 case O_TEE:
 511                         ksnprintf(SNPARGS(action2, 0), "Tee %d", cmd->arg1);
 512                         break;
 513
 514                 case O_SKIPTO:
 515                         ksnprintf(SNPARGS(action2, 0), "SkipTo %d", cmd->arg1);
 516                         break;
 517
 518                 case O_PIPE:
 519                         ksnprintf(SNPARGS(action2, 0), "Pipe %d", cmd->arg1);
 520                         break;
 521
 522                 case O_QUEUE:
 523                         ksnprintf(SNPARGS(action2, 0), "Queue %d", cmd->arg1);
 524                         break;
 525
 526                 case O_FORWARD_IP:
 527                         {
 528                                 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd;
 529                                 int len;
 530
 531                                 len = ksnprintf(SNPARGS(action2, 0),
 532                                                 "Forward to %s",
 533                                                 inet_ntoa(sa->sa.sin_addr));
 534                                 if (sa->sa.sin_port) {
 535                                         ksnprintf(SNPARGS(action2, len), ":%d",
 536                                                   sa->sa.sin_port);
 537                                 }
 538                         }
 539                         break;
 540
 541                 default:
 542                         action = "UNKNOWN";
 543                         break;
 544                 }
 545         }
 546
 547         if (hlen == 0) {        /* non-ip */
 548                 ksnprintf(SNPARGS(proto, 0), "MAC");
 549         } else {
 550                 struct ip *ip = mtod(m, struct ip *);
 551                 /* these three are all aliases to the same thing */
 552                 struct icmp *const icmp = L3HDR(struct icmp, ip);
 553                 struct tcphdr *const tcp = (struct tcphdr *)icmp;
 554                 struct udphdr *const udp = (struct udphdr *)icmp;
 555
 556                 int ip_off, offset, ip_len;
 557                 int len;
 558
 559                 if (eh != NULL) { /* layer 2 packets are as on the wire */
 560                         ip_off = ntohs(ip->ip_off);
 561                         ip_len = ntohs(ip->ip_len);
 562                 } else {
 563                         ip_off = ip->ip_off;
 564                         ip_len = ip->ip_len;
 565                 }
 566                 offset = ip_off & IP_OFFMASK;
 567                 switch (ip->ip_p) {
 568                 case IPPROTO_TCP:
 569                         len = ksnprintf(SNPARGS(proto, 0), "TCP %s",
 570                                         inet_ntoa(ip->ip_src));
 571                         if (offset == 0) {
 572                                 ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
 573                                           ntohs(tcp->th_sport),
 574                                           inet_ntoa(ip->ip_dst),
 575                                           ntohs(tcp->th_dport));
 576                         } else {
 577                                 ksnprintf(SNPARGS(proto, len), " %s",
 578                                           inet_ntoa(ip->ip_dst));
 579                         }
 580                         break;
 581
 582                 case IPPROTO_UDP:
 583                         len = ksnprintf(SNPARGS(proto, 0), "UDP %s",
 584                                         inet_ntoa(ip->ip_src));
 585                         if (offset == 0) {
 586                                 ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
 587                                           ntohs(udp->uh_sport),
 588                                           inet_ntoa(ip->ip_dst),
 589                                           ntohs(udp->uh_dport));
 590                         } else {
 591                                 ksnprintf(SNPARGS(proto, len), " %s",
 592                                           inet_ntoa(ip->ip_dst));
 593                         }
 594                         break;
 595
 596                 case IPPROTO_ICMP:
 597                         if (offset == 0) {
 598                                 len = ksnprintf(SNPARGS(proto, 0),
 599                                                 "ICMP:%u.%u ",
 600                                                 icmp->icmp_type,
 601                                                 icmp->icmp_code);
 602                         } else {
 603                                 len = ksnprintf(SNPARGS(proto, 0), "ICMP ");
 604                         }
 605                         len += ksnprintf(SNPARGS(proto, len), "%s",
 606                                          inet_ntoa(ip->ip_src));
 607                         ksnprintf(SNPARGS(proto, len), " %s",
 608                                   inet_ntoa(ip->ip_dst));
 609                         break;
 610
 611                 default:
 612                         len = ksnprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p,
 613                                         inet_ntoa(ip->ip_src));
 614                         ksnprintf(SNPARGS(proto, len), " %s",
 615                                   inet_ntoa(ip->ip_dst));
 616                         break;
 617                 }
 618
 619                 if (ip_off & (IP_MF | IP_OFFMASK)) {
 620                         ksnprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)",
 621                                   ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2),
 622                                   offset << 3, (ip_off & IP_MF) ? "+" : "");
 623                 }
 624         }
 625
 626         if (oif || m->m_pkthdr.rcvif) {
 627                 log(LOG_SECURITY | LOG_INFO,
 628                     "ipfw: %d %s %s %s via %s%s\n",
 629                     f ? f->rulenum : -1,
 630                     action, proto, oif ? "out" : "in",
 631                     oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname,
 632                     fragment);
 633         } else {
 634                 log(LOG_SECURITY | LOG_INFO,
 635                     "ipfw: %d %s %s [no if info]%s\n",
 636                     f ? f->rulenum : -1,
 637                     action, proto, fragment);
 638         }
 639
 640         if (limit_reached) {
 641                 log(LOG_SECURITY | LOG_NOTICE,
 642                     "ipfw: limit %d reached on entry %d\n",
 643                     limit_reached, f ? f->rulenum : -1);
 644         }
 645 }
 646
 647 #undef SNPARGS
 648
 649 /*
 650  * IMPORTANT: the hash function for dynamic rules must be commutative
 651  * in source and destination (ip,port), because rules are bidirectional
 652  * and we want to find both in the same bucket.
 653  */
 654 static __inline int
 655 hash_packet(struct ipfw_flow_id *id)
 656 {
 657         uint32_t i;
 658
 659         i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
 660         i &= (curr_dyn_buckets - 1);
 661         return i;
 662 }
 663
 664 /**
 665  * unlink a dynamic rule from a chain. prev is a pointer to
 666  * the previous one, q is a pointer to the rule to delete,
 667  * head is a pointer to the head of the queue.
 668  * Modifies q and potentially also head.
 669  */
 670 #define UNLINK_DYN_RULE(prev, head, q)                                  \
 671 do {                                                                    \
 672         ipfw_dyn_rule *old_q = q;                                       \
 673                                                                         \
 674         /* remove a refcount to the parent */                           \
 675         if (q->dyn_type == O_LIMIT)                                     \
 676                 q->parent->count--;                                     \
 677         DEB(kprintf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \
 678                 (q->id.src_ip), (q->id.src_port),                       \
 679                 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); )      \
 680         if (prev != NULL)                                               \
 681                 prev->next = q = q->next;                               \
 682         else                                                            \
 683                 head = q = q->next;                                     \
 684         KASSERT(dyn_count > 0, ("invalid dyn count %u\n", dyn_count));  \
 685         dyn_count--;                                                    \
 686         kfree(old_q, M_IPFW);                                           \
 687 } while (0)
 688
 689 #define TIME_LEQ(a, b)  ((int)((a) - (b)) <= 0)
 690
 691 /**
 692  * Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
 693  *
 694  * If keep_me == NULL, rules are deleted even if not expired,
 695  * otherwise only expired rules are removed.
 696  *
 697  * The value of the second parameter is also used to point to identify
 698  * a rule we absolutely do not want to remove (e.g. because we are
 699  * holding a reference to it -- this is the case with O_LIMIT_PARENT
 700  * rules). The pointer is only used for comparison, so any non-null
 701  * value will do.
 702  */
 703 static void
 704 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
 705 {
 706         static uint32_t last_remove = 0;
 707
 708 #define FORCE   (keep_me == NULL)
 709
 710         ipfw_dyn_rule *prev, *q;
 711         int i, pass = 0, max_pass = 0;
 712
 713         if (ipfw_dyn_v == NULL || dyn_count == 0)
 714                 return;
 715         /* do not expire more than once per second, it is useless */
 716         if (!FORCE && last_remove == time_second)
 717                 return;
 718         last_remove = time_second;
 719
 720         /*
 721          * because O_LIMIT refer to parent rules, during the first pass only
 722          * remove child and mark any pending LIMIT_PARENT, and remove
 723          * them in a second pass.
 724          */
 725 next_pass:
 726         for (i = 0; i < curr_dyn_buckets; i++) {
 727                 for (prev = NULL, q = ipfw_dyn_v[i]; q;) {
 728                         /*
 729                          * Logic can become complex here, so we split tests.
 730                          */
 731                         if (q == keep_me)
 732                                 goto next;
 733                         if (rule != NULL && rule != q->rule)
 734                                 goto next; /* not the one we are looking for */
 735                         if (q->dyn_type == O_LIMIT_PARENT) {
 736                                 /*
 737                                  * handle parent in the second pass,
 738                                  * record we need one.
 739                                  */
 740                                 max_pass = 1;
 741                                 if (pass == 0)
 742                                         goto next;
 743                                 if (FORCE && q->count != 0) {
 744                                         /* XXX should not happen! */
 745                                         kprintf("OUCH! cannot remove rule, "
 746                                                 "count %d\n", q->count);
 747                                 }
 748                         } else {
 749                                 if (!FORCE && !TIME_LEQ(q->expire, time_second))
 750                                         goto next;
 751                         }
 752                         UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
 753                         continue;
 754 next:
 755                         prev = q;
 756                         q = q->next;
 757                 }
 758         }
 759         if (pass++ < max_pass)
 760                 goto next_pass;
 761
 762 #undef FORCE
 763 }
 764
 765
 766 /**
 767  * lookup a dynamic rule.
 768  */
 769 static ipfw_dyn_rule *
 770 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
 771                 struct tcphdr *tcp)
 772 {
 773         /*
 774          * stateful ipfw extensions.
 775          * Lookup into dynamic session queue
 776          */
 777 #define MATCH_REVERSE   0
 778 #define MATCH_FORWARD   1
 779 #define MATCH_NONE      2
 780 #define MATCH_UNKNOWN   3
 781         int i, dir = MATCH_NONE;
 782         ipfw_dyn_rule *prev, *q=NULL;
 783
 784         if (ipfw_dyn_v == NULL)
 785                 goto done;      /* not found */
 786
 787         i = hash_packet(pkt);
 788         for (prev = NULL, q = ipfw_dyn_v[i]; q != NULL;) {
 789                 if (q->dyn_type == O_LIMIT_PARENT)
 790                         goto next;
 791
 792                 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */
 793                         UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
 794                         continue;
 795                 }
 796                 if (pkt->proto == q->id.proto) {
 797                         if (pkt->src_ip == q->id.src_ip &&
 798                             pkt->dst_ip == q->id.dst_ip &&
 799                             pkt->src_port == q->id.src_port &&
 800                             pkt->dst_port == q->id.dst_port) {
 801                                 dir = MATCH_FORWARD;
 802                                 break;
 803                         }
 804                         if (pkt->src_ip == q->id.dst_ip &&
 805                             pkt->dst_ip == q->id.src_ip &&
 806                             pkt->src_port == q->id.dst_port &&
 807                             pkt->dst_port == q->id.src_port) {
 808                                 dir = MATCH_REVERSE;
 809                                 break;
 810                         }
 811                 }
 812 next:
 813                 prev = q;
 814                 q = q->next;
 815         }
 816         if (q == NULL)
 817                 goto done; /* q = NULL, not found */
 818
 819         if (prev != NULL) { /* found and not in front */
 820                 prev->next = q->next;
 821                 q->next = ipfw_dyn_v[i];
 822                 ipfw_dyn_v[i] = q;
 823         }
 824
 825         if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
 826                 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST);
 827
 828 #define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
 829 #define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
 830
 831                 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
 832                 switch (q->state) {
 833                 case TH_SYN:                            /* opening */
 834                         q->expire = time_second + dyn_syn_lifetime;
 835                         break;
 836
 837                 case BOTH_SYN:                  /* move to established */
 838                 case BOTH_SYN | TH_FIN :        /* one side tries to close */
 839                 case BOTH_SYN | (TH_FIN << 8) :
 840                         if (tcp) {
 841                                 uint32_t ack = ntohl(tcp->th_ack);
 842
 843 #define _SEQ_GE(a, b)   ((int)(a) - (int)(b) >= 0)
 844
 845                                 if (dir == MATCH_FORWARD) {
 846                                         if (q->ack_fwd == 0 ||
 847                                             _SEQ_GE(ack, q->ack_fwd))
 848                                                 q->ack_fwd = ack;
 849                                         else /* ignore out-of-sequence */
 850                                                 break;
 851                                 } else {
 852                                         if (q->ack_rev == 0 ||
 853                                             _SEQ_GE(ack, q->ack_rev))
 854                                                 q->ack_rev = ack;
 855                                         else /* ignore out-of-sequence */
 856                                                 break;
 857                                 }
 858 #undef _SEQ_GE
 859                         }
 860                         q->expire = time_second + dyn_ack_lifetime;
 861                         break;
 862
 863                 case BOTH_SYN | BOTH_FIN:       /* both sides closed */
 864                         if (dyn_fin_lifetime >= dyn_keepalive_period)
 865                                 dyn_fin_lifetime = dyn_keepalive_period - 1;
 866                         q->expire = time_second + dyn_fin_lifetime;
 867                         break;
 868
 869                 default:
 870 #if 0
 871                         /*
 872                          * reset or some invalid combination, but can also
 873                          * occur if we use keep-state the wrong way.
 874                          */
 875                         if ((q->state & ((TH_RST << 8) | TH_RST)) == 0)
 876                                 kprintf("invalid state: 0x%x\n", q->state);
 877 #endif
 878                         if (dyn_rst_lifetime >= dyn_keepalive_period)
 879                                 dyn_rst_lifetime = dyn_keepalive_period - 1;
 880                         q->expire = time_second + dyn_rst_lifetime;
 881                         break;
 882                 }
 883         } else if (pkt->proto == IPPROTO_UDP) {
 884                 q->expire = time_second + dyn_udp_lifetime;
 885         } else {
 886                 /* other protocols */
 887                 q->expire = time_second + dyn_short_lifetime;
 888         }
 889 done:
 890         if (match_direction)
 891                 *match_direction = dir;
 892         return q;
 893 }
 894
 895 static void
 896 realloc_dynamic_table(void)
 897 {
 898         /*
 899          * Try reallocation, make sure we have a power of 2 and do
 900          * not allow more than 64k entries. In case of overflow,
 901          * default to 1024.
 902          */
 903
 904         if (dyn_buckets > 65536)
 905                 dyn_buckets = 1024;
 906         if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */
 907                 dyn_buckets = curr_dyn_buckets; /* reset */
 908                 return;
 909         }
 910         curr_dyn_buckets = dyn_buckets;
 911
 912         if (ipfw_dyn_v != NULL)
 913                 kfree(ipfw_dyn_v, M_IPFW);
 914
 915         for (;;) {
 916                 ipfw_dyn_v = kmalloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
 917                                      M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
 918                 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2)
 919                         break;
 920                 curr_dyn_buckets /= 2;
 921         }
 922 }
 923
 924 /**
 925  * Install state of type 'type' for a dynamic session.
 926  * The hash table contains two type of rules:
 927  * - regular rules (O_KEEP_STATE)
 928  * - rules for sessions with limited number of sess per user
 929  *   (O_LIMIT). When they are created, the parent is
 930  *   increased by 1, and decreased on delete. In this case,
 931  *   the third parameter is the parent rule and not the chain.
 932  * - "parent" rules for the above (O_LIMIT_PARENT).
 933  */
 934 static ipfw_dyn_rule *
 935 add_dyn_rule(struct ipfw_flow_id *id, uint8_t dyn_type, struct ip_fw *rule)
 936 {
 937         ipfw_dyn_rule *r;
 938         int i;
 939
 940         if (ipfw_dyn_v == NULL ||
 941             (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) {
 942                 realloc_dynamic_table();
 943                 if (ipfw_dyn_v == NULL)
 944                         return NULL; /* failed ! */
 945         }
 946         i = hash_packet(id);
 947
 948         r = kmalloc(sizeof(*r), M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
 949         if (r == NULL) {
 950                 kprintf ("sorry cannot allocate state\n");
 951                 return NULL;
 952         }
 953
 954         /* increase refcount on parent, and set pointer */
 955         if (dyn_type == O_LIMIT) {
 956                 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
 957
 958                 if (parent->dyn_type != O_LIMIT_PARENT)
 959                         panic("invalid parent");
 960                 parent->count++;
 961                 r->parent = parent;
 962                 rule = parent->rule;
 963         }
 964
 965         r->id = *id;
 966         r->expire = time_second + dyn_syn_lifetime;
 967         r->rule = rule;
 968         r->dyn_type = dyn_type;
 969         r->pcnt = r->bcnt = 0;
 970         r->count = 0;
 971
 972         r->bucket = i;
 973         r->next = ipfw_dyn_v[i];
 974         ipfw_dyn_v[i] = r;
 975         dyn_count++;
 976         DEB(kprintf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n",
 977            dyn_type,
 978            (r->id.src_ip), (r->id.src_port),
 979            (r->id.dst_ip), (r->id.dst_port),
 980            dyn_count );)
 981         return r;
 982 }
 983
 984 /**
 985  * lookup dynamic parent rule using pkt and rule as search keys.
 986  * If the lookup fails, then install one.
 987  */
 988 static ipfw_dyn_rule *
 989 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
 990 {
 991         ipfw_dyn_rule *q;
 992         int i;
 993
 994         if (ipfw_dyn_v) {
 995                 i = hash_packet(pkt);
 996                 for (q = ipfw_dyn_v[i]; q != NULL; q = q->next) {
 997                         if (q->dyn_type == O_LIMIT_PARENT &&
 998                             rule== q->rule &&
 999                             pkt->proto == q->id.proto &&
1000                             pkt->src_ip == q->id.src_ip &&
1001                             pkt->dst_ip == q->id.dst_ip &&
1002                             pkt->src_port == q->id.src_port &&
1003                             pkt->dst_port == q->id.dst_port) {
1004                                 q->expire = time_second + dyn_short_lifetime;
1005                                 DEB(kprintf("lookup_dyn_parent found 0x%p\n",q);)
1006                                 return q;
1007                         }
1008                 }
1009         }
1010         return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
1011 }
1012
1013 /**
1014  * Install dynamic state for rule type cmd->o.opcode
1015  *
1016  * Returns 1 (failure) if state is not installed because of errors or because
1017  * session limitations are enforced.
1018  */
1019 static int
1020 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
1021               struct ip_fw_args *args)
1022 {
1023         static int last_log;
1024
1025         ipfw_dyn_rule *q;
1026
1027         DEB(kprintf("-- install state type %d 0x%08x %u -> 0x%08x %u\n",
1028             cmd->o.opcode,
1029             (args->f_id.src_ip), (args->f_id.src_port),
1030             (args->f_id.dst_ip), (args->f_id.dst_port) );)
1031
1032         q = lookup_dyn_rule(&args->f_id, NULL, NULL);
1033         if (q != NULL) { /* should never occur */
1034                 if (last_log != time_second) {
1035                         last_log = time_second;
1036                         kprintf(" install_state: entry already present, done\n");
1037                 }
1038                 return 0;
1039         }
1040
1041         if (dyn_count >= dyn_max) {
1042                 /*
1043                  * Run out of slots, try to remove any expired rule.
1044                  */
1045                 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);
1046         }
1047
1048         if (dyn_count >= dyn_max) {
1049                 if (last_log != time_second) {
1050                         last_log = time_second;
1051                         kprintf("install_state: Too many dynamic rules\n");
1052                 }
1053                 return 1; /* cannot install, notify caller */
1054         }
1055
1056         switch (cmd->o.opcode) {
1057         case O_KEEP_STATE: /* bidir rule */
1058                 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
1059                 break;
1060
1061         case O_LIMIT: /* limit number of sessions */
1062                 {
1063                         uint16_t limit_mask = cmd->limit_mask;
1064                         struct ipfw_flow_id id;
1065                         ipfw_dyn_rule *parent;
1066
1067                         DEB(kprintf("installing dyn-limit rule %d\n",
1068                             cmd->conn_limit);)
1069
1070                         id.dst_ip = id.src_ip = 0;
1071                         id.dst_port = id.src_port = 0;
1072                         id.proto = args->f_id.proto;
1073
1074                         if (limit_mask & DYN_SRC_ADDR)
1075                                 id.src_ip = args->f_id.src_ip;
1076                         if (limit_mask & DYN_DST_ADDR)
1077                                 id.dst_ip = args->f_id.dst_ip;
1078                         if (limit_mask & DYN_SRC_PORT)
1079                                 id.src_port = args->f_id.src_port;
1080                         if (limit_mask & DYN_DST_PORT)
1081                                 id.dst_port = args->f_id.dst_port;
1082
1083                         parent = lookup_dyn_parent(&id, rule);
1084                         if (parent == NULL) {
1085                                 kprintf("add parent failed\n");
1086                                 return 1;
1087                         }
1088
1089                         if (parent->count >= cmd->conn_limit) {
1090                                 /*
1091                                  * See if we can remove some expired rule.
1092                                  */
1093                                 remove_dyn_rule(rule, parent);
1094                                 if (parent->count >= cmd->conn_limit) {
1095                                         if (fw_verbose &&
1096                                             last_log != time_second) {
1097                                                 last_log = time_second;
1098                                                 log(LOG_SECURITY | LOG_DEBUG,
1099                                                     "drop session, "
1100                                                     "too many entries\n");
1101                                         }
1102                                         return 1;
1103                                 }
1104                         }
1105                         add_dyn_rule(&args->f_id, O_LIMIT,
1106                                      (struct ip_fw *)parent);
1107                 }
1108                 break;
1109         default:
1110                 kprintf("unknown dynamic rule type %u\n", cmd->o.opcode);
1111                 return 1;
1112         }
1113         lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */
1114         return 0;
1115 }
1116
1117 /*
1118  * Transmit a TCP packet, containing either a RST or a keepalive.
1119  * When flags & TH_RST, we are sending a RST packet, because of a
1120  * "reset" action matched the packet.
1121  * Otherwise we are sending a keepalive, and flags & TH_
1122  */
1123 static void
1124 send_pkt(struct ipfw_flow_id *id, uint32_t seq, uint32_t ack, int flags)
1125 {
1126         struct mbuf *m;
1127         struct ip *ip;
1128         struct tcphdr *tcp;
1129         struct route sro;       /* fake route */
1130
1131         MGETHDR(m, MB_DONTWAIT, MT_HEADER);
1132         if (m == 0)
1133                 return;
1134         m->m_pkthdr.rcvif = NULL;
1135         m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
1136         m->m_data += max_linkhdr;
1137
1138         ip = mtod(m, struct ip *);
1139         bzero(ip, m->m_len);
1140         tcp = (struct tcphdr *)(ip + 1); /* no IP options */
1141         ip->ip_p = IPPROTO_TCP;
1142         tcp->th_off = 5;
1143
1144         /*
1145          * Assume we are sending a RST (or a keepalive in the reverse
1146          * direction), swap src and destination addresses and ports.
1147          */
1148         ip->ip_src.s_addr = htonl(id->dst_ip);
1149         ip->ip_dst.s_addr = htonl(id->src_ip);
1150         tcp->th_sport = htons(id->dst_port);
1151         tcp->th_dport = htons(id->src_port);
1152         if (flags & TH_RST) {   /* we are sending a RST */
1153                 if (flags & TH_ACK) {
1154                         tcp->th_seq = htonl(ack);
1155                         tcp->th_ack = htonl(0);
1156                         tcp->th_flags = TH_RST;
1157                 } else {
1158                         if (flags & TH_SYN)
1159                                 seq++;
1160                         tcp->th_seq = htonl(0);
1161                         tcp->th_ack = htonl(seq);
1162                         tcp->th_flags = TH_RST | TH_ACK;
1163                 }
1164         } else {
1165                 /*
1166                  * We are sending a keepalive. flags & TH_SYN determines
1167                  * the direction, forward if set, reverse if clear.
1168                  * NOTE: seq and ack are always assumed to be correct
1169                  * as set by the caller. This may be confusing...
1170                  */
1171                 if (flags & TH_SYN) {
1172                         /*
1173                          * we have to rewrite the correct addresses!
1174                          */
1175                         ip->ip_dst.s_addr = htonl(id->dst_ip);
1176                         ip->ip_src.s_addr = htonl(id->src_ip);
1177                         tcp->th_dport = htons(id->dst_port);
1178                         tcp->th_sport = htons(id->src_port);
1179                 }
1180                 tcp->th_seq = htonl(seq);
1181                 tcp->th_ack = htonl(ack);
1182                 tcp->th_flags = TH_ACK;
1183         }
1184
1185         /*
1186          * set ip_len to the payload size so we can compute
1187          * the tcp checksum on the pseudoheader
1188          * XXX check this, could save a couple of words ?
1189          */
1190         ip->ip_len = htons(sizeof(struct tcphdr));
1191         tcp->th_sum = in_cksum(m, m->m_pkthdr.len);
1192
1193         /*
1194          * now fill fields left out earlier
1195          */
1196         ip->ip_ttl = ip_defttl;
1197         ip->ip_len = m->m_pkthdr.len;
1198
1199         bzero(&sro, sizeof(sro));
1200         ip_rtaddr(ip->ip_dst, &sro);
1201
1202         m->m_pkthdr.fw_flags |= IPFW_MBUF_GENERATED;
1203         ip_output(m, NULL, &sro, 0, NULL, NULL);
1204         if (sro.ro_rt)
1205                 RTFREE(sro.ro_rt);
1206 }
1207
1208 /*
1209  * sends a reject message, consuming the mbuf passed as an argument.
1210  */
1211 static void
1212 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len)
1213 {
1214         if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */
1215                 /* We need the IP header in host order for icmp_error(). */
1216                 if (args->eh != NULL) {
1217                         struct ip *ip = mtod(args->m, struct ip *);
1218
1219                         ip->ip_len = ntohs(ip->ip_len);
1220                         ip->ip_off = ntohs(ip->ip_off);
1221                 }
1222                 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0);
1223         } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) {
1224                 struct tcphdr *const tcp =
1225                     L3HDR(struct tcphdr, mtod(args->m, struct ip *));
1226
1227                 if ((tcp->th_flags & TH_RST) == 0) {
1228                         send_pkt(&args->f_id, ntohl(tcp->th_seq),
1229                                  ntohl(tcp->th_ack), tcp->th_flags | TH_RST);
1230                 }
1231                 m_freem(args->m);
1232         } else {
1233                 m_freem(args->m);
1234         }
1235         args->m = NULL;
1236 }
1237
1238 /**
1239  *
1240  * Given an ip_fw *, lookup_next_rule will return a pointer
1241  * to the next rule, which can be either the jump
1242  * target (for skipto instructions) or the next one in the list (in
1243  * all other cases including a missing jump target).
1244  * The result is also written in the "next_rule" field of the rule.
1245  * Backward jumps are not allowed, so start looking from the next
1246  * rule...
1247  *
1248  * This never returns NULL -- in case we do not have an exact match,
1249  * the next rule is returned. When the ruleset is changed,
1250  * pointers are flushed so we are always correct.
1251  */
1252
1253 static struct ip_fw *
1254 lookup_next_rule(struct ip_fw *me)
1255 {
1256         struct ip_fw *rule = NULL;
1257         ipfw_insn *cmd;
1258
1259         /* look for action, in case it is a skipto */
1260         cmd = ACTION_PTR(me);
1261         if (cmd->opcode == O_LOG)
1262                 cmd += F_LEN(cmd);
1263         if (cmd->opcode == O_SKIPTO) {
1264                 for (rule = me->next; rule; rule = rule->next) {
1265                         if (rule->rulenum >= cmd->arg1)
1266                                 break;
1267                 }
1268         }
1269         if (rule == NULL)                       /* failure or not a skipto */
1270                 rule = me->next;
1271         me->next_rule = rule;
1272         return rule;
1273 }
1274
1275 /*
1276  * The main check routine for the firewall.
1277  *
1278  * All arguments are in args so we can modify them and return them
1279  * back to the caller.
1280  *
1281  * Parameters:
1282  *
1283  *      args->m (in/out) The packet; we set to NULL when/if we nuke it.
1284  *              Starts with the IP header.
1285  *      args->eh (in)   Mac header if present, or NULL for layer3 packet.
1286  *      args->oif       Outgoing interface, or NULL if packet is incoming.
1287  *              The incoming interface is in the mbuf. (in)
1288  *
1289  *      args->rule      Pointer to the last matching rule (in/out)
1290  *      args->next_hop  Socket we are forwarding to (out).
1291  *      args->f_id      Addresses grabbed from the packet (out)
1292  *
1293  * Return value:
1294  *
1295  *      IP_FW_PORT_DENY_FLAG    the packet must be dropped.
1296  *      0       The packet is to be accepted and routed normally OR
1297  *              the packet was denied/rejected and has been dropped;
1298  *              in the latter case, *m is equal to NULL upon return.
1299  *      port    Divert the packet to port, with these caveats:
1300  *
1301  *              - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead
1302  *                of diverting it (ie, 'ipfw tee').
1303  *
1304  *              - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower
1305  *                16 bits as a dummynet pipe number instead of diverting
1306  */
1307
1308 static int
1309 ipfw_chk(struct ip_fw_args *args)
1310 {
1311         /*
1312          * Local variables hold state during the processing of a packet.
1313          *
1314          * IMPORTANT NOTE: to speed up the processing of rules, there
1315          * are some assumption on the values of the variables, which
1316          * are documented here. Should you change them, please check
1317          * the implementation of the various instructions to make sure
1318          * that they still work.
1319          *
1320          * args->eh     The MAC header. It is non-null for a layer2
1321          *      packet, it is NULL for a layer-3 packet.
1322          *
1323          * m | args->m  Pointer to the mbuf, as received from the caller.
1324          *      It may change if ipfw_chk() does an m_pullup, or if it
1325          *      consumes the packet because it calls send_reject().
1326          *      XXX This has to change, so that ipfw_chk() never modifies
1327          *      or consumes the buffer.
1328          * ip   is simply an alias of the value of m, and it is kept
1329          *      in sync with it (the packet is  supposed to start with
1330          *      the ip header).
1331          */
1332         struct mbuf *m = args->m;
1333         struct ip *ip = mtod(m, struct ip *);
1334
1335         /*
1336          * oif | args->oif      If NULL, ipfw_chk has been called on the
1337          *      inbound path (ether_input, ip_input).
1338          *      If non-NULL, ipfw_chk has been called on the outbound path
1339          *      (ether_output, ip_output).
1340          */
1341         struct ifnet *oif = args->oif;
1342
1343         struct ip_fw *f = NULL;         /* matching rule */
1344         int retval = 0;
1345         struct m_tag *mtag;
1346
1347         /*
1348          * hlen The length of the IPv4 header.
1349          *      hlen >0 means we have an IPv4 packet.
1350          */
1351         u_int hlen = 0;         /* hlen >0 means we have an IP pkt */
1352
1353         /*
1354          * offset       The offset of a fragment. offset != 0 means that
1355          *      we have a fragment at this offset of an IPv4 packet.
1356          *      offset == 0 means that (if this is an IPv4 packet)
1357          *      this is the first or only fragment.
1358          */
1359         u_short offset = 0;
1360
1361         /*
1362          * Local copies of addresses. They are only valid if we have
1363          * an IP packet.
1364          *
1365          * proto        The protocol. Set to 0 for non-ip packets,
1366          *      or to the protocol read from the packet otherwise.
1367          *      proto != 0 means that we have an IPv4 packet.
1368          *
1369          * src_port, dst_port   port numbers, in HOST format. Only
1370          *      valid for TCP and UDP packets.
1371          *
1372          * src_ip, dst_ip       ip addresses, in NETWORK format.
1373          *      Only valid for IPv4 packets.
1374          */
1375         uint8_t proto;
1376         uint16_t src_port = 0, dst_port = 0;    /* NOTE: host format    */
1377         struct in_addr src_ip, dst_ip;          /* NOTE: network format */
1378         uint16_t ip_len = 0;
1379         int dyn_dir = MATCH_UNKNOWN;
1380         ipfw_dyn_rule *q = NULL;
1381
1382         if (m->m_pkthdr.fw_flags & IPFW_MBUF_GENERATED)
1383                 return 0;       /* accept */
1384         /*
1385          * dyn_dir = MATCH_UNKNOWN when rules unchecked,
1386          *      MATCH_NONE when checked and not matched (q = NULL),
1387          *      MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL)
1388          */
1389
1390         if (args->eh == NULL ||         /* layer 3 packet */
1391             (m->m_pkthdr.len >= sizeof(struct ip) &&
1392              ntohs(args->eh->ether_type) == ETHERTYPE_IP))
1393                 hlen = ip->ip_hl << 2;
1394
1395         /*
1396          * Collect parameters into local variables for faster matching.
1397          */
1398         if (hlen == 0) {        /* do not grab addresses for non-ip pkts */
1399                 proto = args->f_id.proto = 0;   /* mark f_id invalid */
1400                 goto after_ip_checks;
1401         }
1402
1403         proto = args->f_id.proto = ip->ip_p;
1404         src_ip = ip->ip_src;
1405         dst_ip = ip->ip_dst;
1406         if (args->eh != NULL) { /* layer 2 packets are as on the wire */
1407                 offset = ntohs(ip->ip_off) & IP_OFFMASK;
1408                 ip_len = ntohs(ip->ip_len);
1409         } else {
1410                 offset = ip->ip_off & IP_OFFMASK;
1411                 ip_len = ip->ip_len;
1412         }
1413
1414 #define PULLUP_TO(len)                          \
1415 do {                                            \
1416         if (m->m_len < (len)) {                 \
1417                 args->m = m = m_pullup(m, (len));\
1418                 if (m == NULL)                  \
1419                         goto pullup_failed;     \
1420                 ip = mtod(m, struct ip *);      \
1421         }                                       \
1422 } while (0)
1423
1424         if (offset == 0) {
1425                 switch (proto) {
1426                 case IPPROTO_TCP:
1427                         {
1428                                 struct tcphdr *tcp;
1429
1430                                 PULLUP_TO(hlen + sizeof(struct tcphdr));
1431                                 tcp = L3HDR(struct tcphdr, ip);
1432                                 dst_port = tcp->th_dport;
1433                                 src_port = tcp->th_sport;
1434                                 args->f_id.flags = tcp->th_flags;
1435                         }
1436                         break;
1437
1438                 case IPPROTO_UDP:
1439                         {
1440                                 struct udphdr *udp;
1441
1442                                 PULLUP_TO(hlen + sizeof(struct udphdr));
1443                                 udp = L3HDR(struct udphdr, ip);
1444                                 dst_port = udp->uh_dport;
1445                                 src_port = udp->uh_sport;
1446                         }
1447                         break;
1448
1449                 case IPPROTO_ICMP:
1450                         PULLUP_TO(hlen + 4);    /* type, code and checksum. */
1451                         args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type;
1452                         break;
1453
1454                 default:
1455                         break;
1456                 }
1457         }
1458
1459 #undef PULLUP_TO
1460
1461         args->f_id.src_ip = ntohl(src_ip.s_addr);
1462         args->f_id.dst_ip = ntohl(dst_ip.s_addr);
1463         args->f_id.src_port = src_port = ntohs(src_port);
1464         args->f_id.dst_port = dst_port = ntohs(dst_port);
1465
1466 after_ip_checks:
1467         if (args->rule) {
1468                 /*
1469                  * Packet has already been tagged. Look for the next rule
1470                  * to restart processing.
1471                  *
1472                  * If fw_one_pass != 0 then just accept it.
1473                  * XXX should not happen here, but optimized out in
1474                  * the caller.
1475                  */
1476                 if (fw_one_pass)
1477                         return 0;
1478
1479                 /* This rule was deleted */
1480                 if (args->rule->rule_flags & IPFW_RULE_F_INVALID)
1481                         return IP_FW_PORT_DENY_FLAG;
1482
1483                 f = args->rule->next_rule;
1484                 if (f == NULL)
1485                         f = lookup_next_rule(args->rule);
1486         } else {
1487                 /*
1488                  * Find the starting rule. It can be either the first
1489                  * one, or the one after divert_rule if asked so.
1490                  */
1491                 int skipto;
1492
1493                 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
1494                 if (mtag != NULL)
1495                         skipto = *(uint16_t *)m_tag_data(mtag);
1496                 else
1497                         skipto = 0;
1498
1499                 f = layer3_chain;
1500                 if (args->eh == NULL && skipto != 0) {
1501                         if (skipto >= IPFW_DEFAULT_RULE)
1502                                 return(IP_FW_PORT_DENY_FLAG); /* invalid */
1503                         while (f && f->rulenum <= skipto)
1504                                 f = f->next;
1505                         if (f == NULL)  /* drop packet */
1506                                 return(IP_FW_PORT_DENY_FLAG);
1507                 }
1508         }
1509         if ((mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL)) != NULL)
1510                 m_tag_delete(m, mtag);
1511
1512         /*
1513          * Now scan the rules, and parse microinstructions for each rule.
1514          */
1515         for (; f; f = f->next) {
1516                 int l, cmdlen;
1517                 ipfw_insn *cmd;
1518                 int skip_or; /* skip rest of OR block */
1519
1520 again:
1521                 if (set_disable & (1 << f->set))
1522                         continue;
1523
1524                 skip_or = 0;
1525                 for (l = f->cmd_len, cmd = f->cmd; l > 0;
1526                      l -= cmdlen, cmd += cmdlen) {
1527                         int match;
1528
1529                         /*
1530                          * check_body is a jump target used when we find a
1531                          * CHECK_STATE, and need to jump to the body of
1532                          * the target rule.
1533                          */
1534
1535 check_body:
1536                         cmdlen = F_LEN(cmd);
1537                         /*
1538                          * An OR block (insn_1 || .. || insn_n) has the
1539                          * F_OR bit set in all but the last instruction.
1540                          * The first match will set "skip_or", and cause
1541                          * the following instructions to be skipped until
1542                          * past the one with the F_OR bit clear.
1543                          */
1544                         if (skip_or) {          /* skip this instruction */
1545                                 if ((cmd->len & F_OR) == 0)
1546                                         skip_or = 0;    /* next one is good */
1547                                 continue;
1548                         }
1549                         match = 0; /* set to 1 if we succeed */
1550
1551                         switch (cmd->opcode) {
1552                         /*
1553                          * The first set of opcodes compares the packet's
1554                          * fields with some pattern, setting 'match' if a
1555                          * match is found. At the end of the loop there is
1556                          * logic to deal with F_NOT and F_OR flags associated
1557                          * with the opcode.
1558                          */
1559                         case O_NOP:
1560                                 match = 1;
1561                                 break;
1562
1563                         case O_FORWARD_MAC:
1564                                 kprintf("ipfw: opcode %d unimplemented\n",
1565                                         cmd->opcode);
1566                                 break;
1567
1568                         case O_GID:
1569                         case O_UID:
1570                                 /*
1571                                  * We only check offset == 0 && proto != 0,
1572                                  * as this ensures that we have an IPv4
1573                                  * packet with the ports info.
1574                                  */
1575                                 if (offset!=0)
1576                                         break;
1577                             {
1578                                 struct inpcbinfo *pi;
1579                                 int wildcard;
1580                                 struct inpcb *pcb;
1581
1582                                 if (proto == IPPROTO_TCP) {
1583                                         wildcard = 0;
1584                                         pi = &tcbinfo[mycpu->gd_cpuid];
1585                                 } else if (proto == IPPROTO_UDP) {
1586                                         wildcard = 1;
1587                                         pi = &udbinfo;
1588                                 } else
1589                                         break;
1590
1591                                 pcb =  (oif) ?
1592                                         in_pcblookup_hash(pi,
1593                                             dst_ip, htons(dst_port),
1594                                             src_ip, htons(src_port),
1595                                             wildcard, oif) :
1596                                         in_pcblookup_hash(pi,
1597                                             src_ip, htons(src_port),
1598                                             dst_ip, htons(dst_port),
1599                                             wildcard, NULL);
1600
1601                                 if (pcb == NULL || pcb->inp_socket == NULL)
1602                                         break;
1603
1604                                 if (cmd->opcode == O_UID) {
1605 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b))
1606                                         match =
1607                                           !socheckuid(pcb->inp_socket,
1608                                            (uid_t)((ipfw_insn_u32 *)cmd)->d[0]);
1609 #undef socheckuid
1610                                 } else  {
1611                                         match = groupmember(
1612                                             (uid_t)((ipfw_insn_u32 *)cmd)->d[0],
1613                                             pcb->inp_socket->so_cred);
1614                                 }
1615                             }
1616                                 break;
1617
1618                         case O_RECV:
1619                                 match = iface_match(m->m_pkthdr.rcvif,
1620                                     (ipfw_insn_if *)cmd);
1621                                 break;
1622
1623                         case O_XMIT:
1624                                 match = iface_match(oif, (ipfw_insn_if *)cmd);
1625                                 break;
1626
1627                         case O_VIA:
1628                                 match = iface_match(oif ? oif :
1629                                     m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd);
1630                                 break;
1631
1632                         case O_MACADDR2:
1633                                 if (args->eh != NULL) { /* have MAC header */
1634                                         uint32_t *want = (uint32_t *)
1635                                                 ((ipfw_insn_mac *)cmd)->addr;
1636                                         uint32_t *mask = (uint32_t *)
1637                                                 ((ipfw_insn_mac *)cmd)->mask;
1638                                         uint32_t *hdr = (uint32_t *)args->eh;
1639
1640                                         match =
1641                                         (want[0] == (hdr[0] & mask[0]) &&
1642                                          want[1] == (hdr[1] & mask[1]) &&
1643                                          want[2] == (hdr[2] & mask[2]));
1644                                 }
1645                                 break;
1646
1647                         case O_MAC_TYPE:
1648                                 if (args->eh != NULL) {
1649                                         uint16_t t =
1650                                             ntohs(args->eh->ether_type);
1651                                         uint16_t *p =
1652                                             ((ipfw_insn_u16 *)cmd)->ports;
1653                                         int i;
1654
1655                                         /* Special vlan handling */
1656                                         if (m->m_flags & M_VLANTAG)
1657                                                 t = ETHERTYPE_VLAN;
1658
1659                                         for (i = cmdlen - 1; !match && i > 0;
1660                                              i--, p += 2) {
1661                                                 match =
1662                                                 (t >= p[0] && t <= p[1]);
1663                                         }
1664                                 }
1665                                 break;
1666
1667                         case O_FRAG:
1668                                 match = (hlen > 0 && offset != 0);
1669                                 break;
1670
1671                         case O_IN:      /* "out" is "not in" */
1672                                 match = (oif == NULL);
1673                                 break;
1674
1675                         case O_LAYER2:
1676                                 match = (args->eh != NULL);
1677                                 break;
1678
1679                         case O_PROTO:
1680                                 /*
1681                                  * We do not allow an arg of 0 so the
1682                                  * check of "proto" only suffices.
1683                                  */
1684                                 match = (proto == cmd->arg1);
1685                                 break;
1686
1687                         case O_IP_SRC:
1688                                 match = (hlen > 0 &&
1689                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1690                                     src_ip.s_addr);
1691                                 break;
1692
1693                         case O_IP_SRC_MASK:
1694                                 match = (hlen > 0 &&
1695                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1696                                      (src_ip.s_addr &
1697                                      ((ipfw_insn_ip *)cmd)->mask.s_addr));
1698                                 break;
1699
1700                         case O_IP_SRC_ME:
1701                                 if (hlen > 0) {
1702                                         struct ifnet *tif;
1703
1704                                         tif = INADDR_TO_IFP(&src_ip);
1705                                         match = (tif != NULL);
1706                                 }
1707                                 break;
1708
1709                         case O_IP_DST_SET:
1710                         case O_IP_SRC_SET:
1711                                 if (hlen > 0) {
1712                                         uint32_t *d = (uint32_t *)(cmd+1);
1713                                         uint32_t addr =
1714                                             cmd->opcode == O_IP_DST_SET ?
1715                                                 args->f_id.dst_ip :
1716                                                 args->f_id.src_ip;
1717
1718                                         if (addr < d[0])
1719                                                 break;
1720                                         addr -= d[0]; /* subtract base */
1721                                         match =
1722                                         (addr < cmd->arg1) &&
1723                                          (d[1 + (addr >> 5)] &
1724                                           (1 << (addr & 0x1f)));
1725                                 }
1726                                 break;
1727
1728                         case O_IP_DST:
1729                                 match = (hlen > 0 &&
1730                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1731                                     dst_ip.s_addr);
1732                                 break;
1733
1734                         case O_IP_DST_MASK:
1735                                 match = (hlen > 0) &&
1736                                     (((ipfw_insn_ip *)cmd)->addr.s_addr ==
1737                                      (dst_ip.s_addr &
1738                                      ((ipfw_insn_ip *)cmd)->mask.s_addr));
1739                                 break;
1740
1741                         case O_IP_DST_ME:
1742                                 if (hlen > 0) {
1743                                         struct ifnet *tif;
1744
1745                                         tif = INADDR_TO_IFP(&dst_ip);
1746                                         match = (tif != NULL);
1747                                 }
1748                                 break;
1749
1750                         case O_IP_SRCPORT:
1751                         case O_IP_DSTPORT:
1752                                 /*
1753                                  * offset == 0 && proto != 0 is enough
1754                                  * to guarantee that we have an IPv4
1755                                  * packet with port info.
1756                                  */
1757                                 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP)
1758                                     && offset == 0) {
1759                                         uint16_t x =
1760                                             (cmd->opcode == O_IP_SRCPORT) ?
1761                                                 src_port : dst_port ;
1762                                         uint16_t *p =
1763                                             ((ipfw_insn_u16 *)cmd)->ports;
1764                                         int i;
1765
1766                                         for (i = cmdlen - 1; !match && i > 0;
1767                                              i--, p += 2) {
1768                                                 match =
1769                                                 (x >= p[0] && x <= p[1]);
1770                                         }
1771                                 }
1772                                 break;
1773
1774                         case O_ICMPTYPE:
1775                                 match = (offset == 0 && proto==IPPROTO_ICMP &&
1776                                     icmptype_match(ip, (ipfw_insn_u32 *)cmd));
1777                                 break;
1778
1779                         case O_IPOPT:
1780                                 match = (hlen > 0 && ipopts_match(ip, cmd));
1781                                 break;
1782
1783                         case O_IPVER:
1784                                 match = (hlen > 0 && cmd->arg1 == ip->ip_v);
1785                                 break;
1786
1787                         case O_IPTTL:
1788                                 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl);
1789                                 break;
1790
1791                         case O_IPID:
1792                                 match = (hlen > 0 &&
1793                                     cmd->arg1 == ntohs(ip->ip_id));
1794                                 break;
1795
1796                         case O_IPLEN:
1797                                 match = (hlen > 0 && cmd->arg1 == ip_len);
1798                                 break;
1799
1800                         case O_IPPRECEDENCE:
1801                                 match = (hlen > 0 &&
1802                                     (cmd->arg1 == (ip->ip_tos & 0xe0)));
1803                                 break;
1804
1805                         case O_IPTOS:
1806                                 match = (hlen > 0 &&
1807                                     flags_match(cmd, ip->ip_tos));
1808                                 break;
1809
1810                         case O_TCPFLAGS:
1811                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1812                                     flags_match(cmd,
1813                                         L3HDR(struct tcphdr,ip)->th_flags));
1814                                 break;
1815
1816                         case O_TCPOPTS:
1817                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1818                                     tcpopts_match(ip, cmd));
1819                                 break;
1820
1821                         case O_TCPSEQ:
1822                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1823                                     ((ipfw_insn_u32 *)cmd)->d[0] ==
1824                                         L3HDR(struct tcphdr,ip)->th_seq);
1825                                 break;
1826
1827                         case O_TCPACK:
1828                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1829                                     ((ipfw_insn_u32 *)cmd)->d[0] ==
1830                                         L3HDR(struct tcphdr,ip)->th_ack);
1831                                 break;
1832
1833                         case O_TCPWIN:
1834                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1835                                     cmd->arg1 ==
1836                                         L3HDR(struct tcphdr,ip)->th_win);
1837                                 break;
1838
1839                         case O_ESTAB:
1840                                 /* reject packets which have SYN only */
1841                                 /* XXX should i also check for TH_ACK ? */
1842                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1843                                     (L3HDR(struct tcphdr,ip)->th_flags &
1844                                      (TH_RST | TH_ACK | TH_SYN)) != TH_SYN);
1845                                 break;
1846
1847                         case O_LOG:
1848                                 if (fw_verbose)
1849                                         ipfw_log(f, hlen, args->eh, m, oif);
1850                                 match = 1;
1851                                 break;
1852
1853                         case O_PROB:
1854                                 match = (krandom() <
1855                                         ((ipfw_insn_u32 *)cmd)->d[0]);
1856                                 break;
1857
1858                         /*
1859                          * The second set of opcodes represents 'actions',
1860                          * i.e. the terminal part of a rule once the packet
1861                          * matches all previous patterns.
1862                          * Typically there is only one action for each rule,
1863                          * and the opcode is stored at the end of the rule
1864                          * (but there are exceptions -- see below).
1865                          *
1866                          * In general, here we set retval and terminate the
1867                          * outer loop (would be a 'break 3' in some language,
1868                          * but we need to do a 'goto done').
1869                          *
1870                          * Exceptions:
1871                          * O_COUNT and O_SKIPTO actions:
1872                          *   instead of terminating, we jump to the next rule
1873                          *   ('goto next_rule', equivalent to a 'break 2'),
1874                          *   or to the SKIPTO target ('goto again' after
1875                          *   having set f, cmd and l), respectively.
1876                          *
1877                          * O_LIMIT and O_KEEP_STATE: these opcodes are
1878                          *   not real 'actions', and are stored right
1879                          *   before the 'action' part of the rule.
1880                          *   These opcodes try to install an entry in the
1881                          *   state tables; if successful, we continue with
1882                          *   the next opcode (match=1; break;), otherwise
1883                          *   the packet *   must be dropped
1884                          *   ('goto done' after setting retval);
1885                          *
1886                          * O_PROBE_STATE and O_CHECK_STATE: these opcodes
1887                          *   cause a lookup of the state table, and a jump
1888                          *   to the 'action' part of the parent rule
1889                          *   ('goto check_body') if an entry is found, or
1890                          *   (CHECK_STATE only) a jump to the next rule if
1891                          *   the entry is not found ('goto next_rule').
1892                          *   The result of the lookup is cached to make
1893                          *   further instances of these opcodes are
1894                          *   effectively NOPs.
1895                          */
1896                         case O_LIMIT:
1897                         case O_KEEP_STATE:
1898                                 if (install_state(f,
1899                                     (ipfw_insn_limit *)cmd, args)) {
1900                                         retval = IP_FW_PORT_DENY_FLAG;
1901                                         goto done; /* error/limit violation */
1902                                 }
1903                                 match = 1;
1904                                 break;
1905
1906                         case O_PROBE_STATE:
1907                         case O_CHECK_STATE:
1908                                 /*
1909                                  * dynamic rules are checked at the first
1910                                  * keep-state or check-state occurrence,
1911                                  * with the result being stored in dyn_dir.
1912                                  * The compiler introduces a PROBE_STATE
1913                                  * instruction for us when we have a
1914                                  * KEEP_STATE (because PROBE_STATE needs
1915                                  * to be run first).
1916                                  */
1917                                 if (dyn_dir == MATCH_UNKNOWN &&
1918                                     (q = lookup_dyn_rule(&args->f_id,
1919                                      &dyn_dir, proto == IPPROTO_TCP ?
1920                                         L3HDR(struct tcphdr, ip) : NULL))
1921                                         != NULL) {
1922                                         /*
1923                                          * Found dynamic entry, update stats
1924                                          * and jump to the 'action' part of
1925                                          * the parent rule.
1926                                          */
1927                                         q->pcnt++;
1928                                         q->bcnt += ip_len;
1929                                         f = q->rule;
1930                                         cmd = ACTION_PTR(f);
1931                                         l = f->cmd_len - f->act_ofs;
1932                                         goto check_body;
1933                                 }
1934                                 /*
1935                                  * Dynamic entry not found. If CHECK_STATE,
1936                                  * skip to next rule, if PROBE_STATE just
1937                                  * ignore and continue with next opcode.
1938                                  */
1939                                 if (cmd->opcode == O_CHECK_STATE)
1940                                         goto next_rule;
1941                                 match = 1;
1942                                 break;
1943
1944                         case O_ACCEPT:
1945                                 retval = 0;     /* accept */
1946                                 goto done;
1947
1948                         case O_PIPE:
1949                         case O_QUEUE:
1950                                 args->rule = f; /* report matching rule */
1951                                 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG;
1952                                 goto done;
1953
1954                         case O_DIVERT:
1955                         case O_TEE:
1956                                 if (args->eh) /* not on layer 2 */
1957                                         break;
1958
1959                                 mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT,
1960                                                  sizeof(uint16_t), MB_DONTWAIT);
1961                                 if (mtag == NULL) {
1962                                         retval = IP_FW_PORT_DENY_FLAG;
1963                                         goto done;
1964                                 }
1965                                 *(uint16_t *)m_tag_data(mtag) = f->rulenum;
1966                                 m_tag_prepend(m, mtag);
1967                                 retval = (cmd->opcode == O_DIVERT) ?
1968                                     cmd->arg1 :
1969                                     cmd->arg1 | IP_FW_PORT_TEE_FLAG;
1970                                 goto done;
1971
1972                         case O_COUNT:
1973                         case O_SKIPTO:
1974                                 f->pcnt++;      /* update stats */
1975                                 f->bcnt += ip_len;
1976                                 f->timestamp = time_second;
1977                                 if (cmd->opcode == O_COUNT)
1978                                         goto next_rule;
1979                                 /* handle skipto */
1980                                 if (f->next_rule == NULL)
1981                                         lookup_next_rule(f);
1982                                 f = f->next_rule;
1983                                 goto again;
1984
1985                         case O_REJECT:
1986                                 /*
1987                                  * Drop the packet and send a reject notice
1988                                  * if the packet is not ICMP (or is an ICMP
1989                                  * query), and it is not multicast/broadcast.
1990                                  */
1991                                 if (hlen > 0 &&
1992                                     (proto != IPPROTO_ICMP ||
1993                                      is_icmp_query(ip)) &&
1994                                     !(m->m_flags & (M_BCAST|M_MCAST)) &&
1995                                     !IN_MULTICAST(ntohl(dst_ip.s_addr))) {
1996                                         send_reject(args, cmd->arg1,
1997                                             offset,ip_len);
1998                                         m = args->m;
1999                                 }
2000                                 /* FALLTHROUGH */
2001                         case O_DENY:
2002                                 retval = IP_FW_PORT_DENY_FLAG;
2003                                 goto done;
2004
2005                         case O_FORWARD_IP:
2006                                 if (args->eh)   /* not valid on layer2 pkts */
2007                                         break;
2008                                 if (!q || dyn_dir == MATCH_FORWARD) {
2009                                         args->next_hop =
2010                                             &((ipfw_insn_sa *)cmd)->sa;
2011                                 }
2012                                 retval = 0;
2013                                 goto done;
2014
2015                         default:
2016                                 panic("-- unknown opcode %d\n", cmd->opcode);
2017                         } /* end of switch() on opcodes */
2018
2019                         if (cmd->len & F_NOT)
2020                                 match = !match;
2021
2022                         if (match) {
2023                                 if (cmd->len & F_OR)
2024                                         skip_or = 1;
2025                         } else {
2026                                 if (!(cmd->len & F_OR)) /* not an OR block, */
2027                                         break;          /* try next rule    */
2028                         }
2029
2030                 }       /* end of inner for, scan opcodes */
2031
2032 next_rule:;             /* try next rule                */
2033
2034         }               /* end of outer for, scan rules */
2035         kprintf("+++ ipfw: ouch!, skip past end of rules, denying packet\n");
2036         return(IP_FW_PORT_DENY_FLAG);
2037
2038 done:
2039         /* Update statistics */
2040         f->pcnt++;
2041         f->bcnt += ip_len;
2042         f->timestamp = time_second;
2043         return retval;
2044
2045 pullup_failed:
2046         if (fw_verbose)
2047                 kprintf("pullup failed\n");
2048         return(IP_FW_PORT_DENY_FLAG);
2049 }
2050
2051 static void
2052 ipfw_dummynet_io(struct mbuf *m, int pipe_nr, int dir, struct ip_fw_args *fwa)
2053 {
2054         struct m_tag *mtag;
2055         struct dn_pkt *pkt;
2056         ipfw_insn *cmd;
2057         const struct ipfw_flow_id *id;
2058         struct dn_flow_id *fid;
2059
2060         M_ASSERTPKTHDR(m);
2061
2062         mtag = m_tag_get(PACKET_TAG_DUMMYNET, sizeof(*pkt), MB_DONTWAIT);
2063         if (mtag == NULL) {
2064                 m_freem(m);
2065                 return;
2066         }
2067         m_tag_prepend(m, mtag);
2068
2069         pkt = m_tag_data(mtag);
2070         bzero(pkt, sizeof(*pkt));
2071
2072         cmd = fwa->rule->cmd + fwa->rule->act_ofs;
2073         if (cmd->opcode == O_LOG)
2074                 cmd += F_LEN(cmd);
2075         KASSERT(cmd->opcode == O_PIPE || cmd->opcode == O_QUEUE,
2076                 ("Rule is not PIPE or QUEUE, opcode %d\n", cmd->opcode));
2077
2078         pkt->dn_m = m;
2079         pkt->dn_flags = (dir & DN_FLAGS_DIR_MASK);
2080         pkt->ifp = fwa->oif;
2081         pkt->cpuid = mycpu->gd_cpuid;
2082         pkt->pipe_nr = pipe_nr;
2083
2084         id = &fwa->f_id;
2085         fid = &pkt->id;
2086         fid->fid_dst_ip = id->dst_ip;
2087         fid->fid_src_ip = id->src_ip;
2088         fid->fid_dst_port = id->dst_port;
2089         fid->fid_src_port = id->src_port;
2090         fid->fid_proto = id->proto;
2091         fid->fid_flags = id->flags;
2092
2093         ipfw_ref_rule(fwa->rule);
2094         pkt->dn_priv = fwa->rule;
2095         pkt->dn_unref_priv = ipfw_unref_rule;
2096
2097         if (cmd->opcode == O_PIPE)
2098                 pkt->dn_flags |= DN_FLAGS_IS_PIPE;
2099
2100         if (dir == DN_TO_IP_OUT) {
2101                 /*
2102                  * We need to copy *ro because for ICMP pkts (and maybe
2103                  * others) the caller passed a pointer into the stack;
2104                  * dst might also be a pointer into *ro so it needs to
2105                  * be updated.
2106                  */
2107                 pkt->ro = *(fwa->ro);
2108                 if (fwa->ro->ro_rt)
2109                         fwa->ro->ro_rt->rt_refcnt++;
2110                 if (fwa->dst == (struct sockaddr_in *)&fwa->ro->ro_dst) {
2111                         /* 'dst' points into 'ro' */
2112                         fwa->dst = (struct sockaddr_in *)&(pkt->ro.ro_dst);
2113                 }
2114                 pkt->dn_dst = fwa->dst;
2115                 pkt->flags = fwa->flags;
2116         }
2117
2118         m->m_pkthdr.fw_flags |= DUMMYNET_MBUF_TAGGED;
2119         ip_dn_queue(m);
2120 }
2121
2122 /*
2123  * When a rule is added/deleted, clear the next_rule pointers in all rules.
2124  * These will be reconstructed on the fly as packets are matched.
2125  * Must be called at splimp().
2126  */
2127 static void
2128 flush_rule_ptrs(void)
2129 {
2130         struct ip_fw *rule;
2131
2132         for (rule = layer3_chain; rule; rule = rule->next)
2133                 rule->next_rule = NULL;
2134 }
2135
2136 static __inline void
2137 ipfw_inc_static_count(struct ip_fw *rule)
2138 {
2139         KASSERT(mycpuid == 0,
2140                 ("adding static rule not on cpu0 (%d)", mycpuid));
2141
2142         static_count++;
2143         static_ioc_len += IOC_RULESIZE(rule);
2144 }
2145
2146 static __inline void
2147 ipfw_dec_static_count(struct ip_fw *rule)
2148 {
2149         int l = IOC_RULESIZE(rule);
2150
2151         KASSERT(mycpuid == 0,
2152                 ("deleting static rule not on cpu0 (%d)", mycpuid));
2153
2154         KASSERT(static_count > 0, ("invalid static count %u\n", static_count));
2155         static_count--;
2156
2157         KASSERT(static_ioc_len >= l,
2158                 ("invalid static len %u\n", static_ioc_len));
2159         static_ioc_len -= l;
2160 }
2161
2162 static struct ip_fw *
2163 ipfw_create_rule(const struct ipfw_ioc_rule *ioc_rule)
2164 {
2165         struct ip_fw *rule;
2166
2167         rule = kmalloc(RULESIZE(ioc_rule), M_IPFW, M_WAITOK | M_ZERO);
2168
2169         rule->act_ofs = ioc_rule->act_ofs;
2170         rule->cmd_len = ioc_rule->cmd_len;
2171         rule->rulenum = ioc_rule->rulenum;
2172         rule->set = ioc_rule->set;
2173         rule->usr_flags = ioc_rule->usr_flags;
2174
2175         bcopy(ioc_rule->cmd, rule->cmd, rule->cmd_len * 4 /* XXX */);
2176
2177         rule->refcnt = 1;
2178
2179         return rule;
2180 }
2181
2182 /*
2183  * Add a new rule to the list. Copy the rule into a malloc'ed area, then
2184  * possibly create a rule number and add the rule to the list.
2185  * Update the rule_number in the input struct so the caller knows it as well.
2186  */
2187 static int
2188 ipfw_add_rule(struct ip_fw **head, struct ipfw_ioc_rule *ioc_rule)
2189 {
2190         struct ip_fw *rule, *f, *prev;
2191
2192         KKASSERT(*head != NULL);
2193
2194         rule = ipfw_create_rule(ioc_rule);
2195
2196         crit_enter();
2197
2198         /*
2199          * If rulenum is 0, find highest numbered rule before the
2200          * default rule, and add autoinc_step
2201          */
2202         if (autoinc_step < 1)
2203                 autoinc_step = 1;
2204         else if (autoinc_step > 1000)
2205                 autoinc_step = 1000;
2206         if (rule->rulenum == 0) {
2207                 /*
2208                  * locate the highest numbered rule before default
2209                  */
2210                 for (f = *head; f; f = f->next) {
2211                         if (f->rulenum == IPFW_DEFAULT_RULE)
2212                                 break;
2213                         rule->rulenum = f->rulenum;
2214                 }
2215                 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step)
2216                         rule->rulenum += autoinc_step;
2217                 ioc_rule->rulenum = rule->rulenum;
2218         }
2219
2220         /*
2221          * Now insert the new rule in the right place in the sorted list.
2222          */
2223         for (prev = NULL, f = *head; f; prev = f, f = f->next) {
2224                 if (f->rulenum > rule->rulenum) { /* found the location */
2225                         if (prev) {
2226                                 rule->next = f;
2227                                 prev->next = rule;
2228                         } else { /* head insert */
2229                                 rule->next = *head;
2230                                 *head = rule;
2231                         }
2232                         break;
2233                 }
2234         }
2235
2236         flush_rule_ptrs();
2237         ipfw_inc_static_count(rule);
2238
2239         crit_exit();
2240
2241         DEB(kprintf("++ installed rule %d, static count now %d\n",
2242                 rule->rulenum, static_count);)
2243         return (0);
2244 }
2245
2246 /**
2247  * Free storage associated with a static rule (including derived
2248  * dynamic rules).
2249  * The caller is in charge of clearing rule pointers to avoid
2250  * dangling pointers.
2251  * @return a pointer to the next entry.
2252  * Arguments are not checked, so they better be correct.
2253  * Must be called at splimp().
2254  */
2255 static struct ip_fw *
2256 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule)
2257 {
2258         struct ip_fw *n;
2259
2260         n = rule->next;
2261         remove_dyn_rule(rule, NULL /* force removal */);
2262         if (prev == NULL)
2263                 *head = n;
2264         else
2265                 prev->next = n;
2266         ipfw_dec_static_count(rule);
2267
2268         /* Mark the rule as invalid */
2269         rule->rule_flags |= IPFW_RULE_F_INVALID;
2270         rule->next_rule = NULL;
2271
2272         /* Try to free this rule */
2273         ipfw_free_rule(rule);
2274
2275         return n;
2276 }
2277
2278 /*
2279  * Deletes all rules from a chain (including the default rule
2280  * if the second argument is set).
2281  * Must be called at splimp().
2282  */
2283 static void
2284 free_chain(struct ip_fw **chain, int kill_default)
2285 {
2286         struct ip_fw *rule;
2287
2288         flush_rule_ptrs(); /* more efficient to do outside the loop */
2289
2290         while ((rule = *chain) != NULL &&
2291                (kill_default || rule->rulenum != IPFW_DEFAULT_RULE))
2292                 delete_rule(chain, NULL, rule);
2293
2294         KASSERT(dyn_count == 0, ("%u dyn rule remains\n", dyn_count));
2295
2296         if (kill_default) {
2297                 ip_fw_default_rule = NULL;      /* Reset default rule */
2298
2299                 if (ipfw_dyn_v != NULL) {
2300                         /*
2301                          * Free dynamic rules(state) hash table
2302                          */
2303                         kfree(ipfw_dyn_v, M_IPFW);
2304                         ipfw_dyn_v = NULL;
2305                 }
2306
2307                 KASSERT(static_count == 0,
2308                         ("%u static rules remains\n", static_count));
2309                 KASSERT(static_ioc_len == 0,
2310                         ("%u bytes of static rules remains\n", static_ioc_len));
2311         } else {
2312                 KASSERT(static_count == 1,
2313                         ("%u static rules remains\n", static_count));
2314                 KASSERT(static_ioc_len == IOC_RULESIZE(ip_fw_default_rule),
2315                         ("%u bytes of static rules remains, should be %u\n",
2316                          static_ioc_len, IOC_RULESIZE(ip_fw_default_rule)));
2317         }
2318 }
2319
2320 /**
2321  * Remove all rules with given number, and also do set manipulation.
2322  *
2323  * The argument is an uint32_t. The low 16 bit are the rule or set number,
2324  * the next 8 bits are the new set, the top 8 bits are the command:
2325  *
2326  *      0       delete rules with given number
2327  *      1       delete rules with given set number
2328  *      2       move rules with given number to new set
2329  *      3       move rules with given set number to new set
2330  *      4       swap sets with given numbers
2331  */
2332 static int
2333 del_entry(struct ip_fw **chain, uint32_t arg)
2334 {
2335         struct ip_fw *prev, *rule;
2336         uint16_t rulenum;
2337         uint8_t cmd, new_set;
2338
2339         rulenum = arg & 0xffff;
2340         cmd = (arg >> 24) & 0xff;
2341         new_set = (arg >> 16) & 0xff;
2342
2343         if (cmd > 4)
2344                 return EINVAL;
2345         if (new_set > 30)
2346                 return EINVAL;
2347         if (cmd == 0 || cmd == 2) {
2348                 if (rulenum == IPFW_DEFAULT_RULE)
2349                         return EINVAL;
2350         } else {
2351                 if (rulenum > 30)
2352                         return EINVAL;
2353         }
2354
2355         switch (cmd) {
2356         case 0: /* delete rules with given number */
2357                 /*
2358                  * locate first rule to delete
2359                  */
2360                 for (prev = NULL, rule = *chain;
2361                      rule && rule->rulenum < rulenum;
2362                      prev = rule, rule = rule->next)
2363                         ;
2364                 if (rule->rulenum != rulenum)
2365                         return EINVAL;
2366
2367                 crit_enter(); /* no access to rules while removing */
2368                 /*
2369                  * flush pointers outside the loop, then delete all matching
2370                  * rules. prev remains the same throughout the cycle.
2371                  */
2372                 flush_rule_ptrs();
2373                 while (rule && rule->rulenum == rulenum)
2374                         rule = delete_rule(chain, prev, rule);
2375                 crit_exit();
2376                 break;
2377
2378         case 1: /* delete all rules with given set number */
2379                 crit_enter();
2380                 flush_rule_ptrs();
2381                 for (prev = NULL, rule = *chain; rule;) {
2382                         if (rule->set == rulenum) {
2383                                 rule = delete_rule(chain, prev, rule);
2384                         } else {
2385                                 prev = rule;
2386                                 rule = rule->next;
2387                         }
2388                 }
2389                 crit_exit();
2390                 break;
2391
2392         case 2: /* move rules with given number to new set */
2393                 crit_enter();
2394                 for (rule = *chain; rule; rule = rule->next) {
2395                         if (rule->rulenum == rulenum)
2396                                 rule->set = new_set;
2397                 }
2398                 crit_exit();
2399                 break;
2400
2401         case 3: /* move rules with given set number to new set */
2402                 crit_enter();
2403                 for (rule = *chain; rule; rule = rule->next) {
2404                         if (rule->set == rulenum)
2405                                 rule->set = new_set;
2406                 }
2407                 crit_exit();
2408                 break;
2409
2410         case 4: /* swap two sets */
2411                 crit_enter();
2412                 for (rule = *chain; rule; rule = rule->next) {
2413                         if (rule->set == rulenum)
2414                                 rule->set = new_set;
2415                         else if (rule->set == new_set)
2416                                 rule->set = rulenum;
2417                 }
2418                 crit_exit();
2419                 break;
2420         }
2421         return 0;
2422 }
2423
2424 /*
2425  * Clear counters for a specific rule.
2426  */
2427 static void
2428 clear_counters(struct ip_fw *rule, int log_only)
2429 {
2430         ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule);
2431
2432         if (log_only == 0) {
2433                 rule->bcnt = rule->pcnt = 0;
2434                 rule->timestamp = 0;
2435         }
2436         if (l->o.opcode == O_LOG)
2437                 l->log_left = l->max_log;
2438 }
2439
2440 /**
2441  * Reset some or all counters on firewall rules.
2442  * @arg frwl is null to clear all entries, or contains a specific
2443  * rule number.
2444  * @arg log_only is 1 if we only want to reset logs, zero otherwise.
2445  */
2446 static int
2447 zero_entry(int rulenum, int log_only)
2448 {
2449         struct ip_fw *rule;
2450         char *msg;
2451
2452         if (rulenum == 0) {
2453                 crit_enter();
2454                 norule_counter = 0;
2455                 for (rule = layer3_chain; rule; rule = rule->next)
2456                         clear_counters(rule, log_only);
2457                 crit_exit();
2458                 msg = log_only ? "ipfw: All logging counts reset.\n"
2459                                : "ipfw: Accounting cleared.\n";
2460         } else {
2461                 int cleared = 0;
2462
2463                 /*
2464                  * We can have multiple rules with the same number, so we
2465                  * need to clear them all.
2466                  */
2467                 for (rule = layer3_chain; rule; rule = rule->next) {
2468                         if (rule->rulenum == rulenum) {
2469                                 crit_enter();
2470                                 while (rule && rule->rulenum == rulenum) {
2471                                         clear_counters(rule, log_only);
2472                                         rule = rule->next;
2473                                 }
2474                                 crit_exit();
2475                                 cleared = 1;
2476                                 break;
2477                         }
2478                 }
2479                 if (!cleared)   /* we did not find any matching rules */
2480                         return (EINVAL);
2481                 msg = log_only ? "ipfw: Entry %d logging count reset.\n"
2482                                : "ipfw: Entry %d cleared.\n";
2483         }
2484         if (fw_verbose)
2485                 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum);
2486         return (0);
2487 }
2488
2489 /*
2490  * Check validity of the structure before insert.
2491  * Fortunately rules are simple, so this mostly need to check rule sizes.
2492  */
2493 static int
2494 ipfw_ctl_check_rule(struct ipfw_ioc_rule *rule, int size)
2495 {
2496         int l, cmdlen = 0;
2497         int have_action = 0;
2498         ipfw_insn *cmd;
2499
2500         /* Check for valid size */
2501         if (size < sizeof(*rule)) {
2502                 kprintf("ipfw: rule too short\n");
2503                 return EINVAL;
2504         }
2505         l = IOC_RULESIZE(rule);
2506         if (l != size) {
2507                 kprintf("ipfw: size mismatch (have %d want %d)\n", size, l);
2508                 return EINVAL;
2509         }
2510
2511         /*
2512          * Now go for the individual checks. Very simple ones, basically only
2513          * instruction sizes.
2514          */
2515         for (l = rule->cmd_len, cmd = rule->cmd; l > 0;
2516              l -= cmdlen, cmd += cmdlen) {
2517                 cmdlen = F_LEN(cmd);
2518                 if (cmdlen > l) {
2519                         kprintf("ipfw: opcode %d size truncated\n",
2520                                 cmd->opcode);
2521                         return EINVAL;
2522                 }
2523                 DEB(kprintf("ipfw: opcode %d\n", cmd->opcode);)
2524                 switch (cmd->opcode) {
2525                 case O_NOP:
2526                 case O_PROBE_STATE:
2527                 case O_KEEP_STATE:
2528                 case O_PROTO:
2529                 case O_IP_SRC_ME:
2530                 case O_IP_DST_ME:
2531                 case O_LAYER2:
2532                 case O_IN:
2533                 case O_FRAG:
2534                 case O_IPOPT:
2535                 case O_IPLEN:
2536                 case O_IPID:
2537                 case O_IPTOS:
2538                 case O_IPPRECEDENCE:
2539                 case O_IPTTL:
2540                 case O_IPVER:
2541                 case O_TCPWIN:
2542                 case O_TCPFLAGS:
2543                 case O_TCPOPTS:
2544                 case O_ESTAB:
2545                         if (cmdlen != F_INSN_SIZE(ipfw_insn))
2546                                 goto bad_size;
2547                         break;
2548
2549                 case O_UID:
2550                 case O_GID:
2551                 case O_IP_SRC:
2552                 case O_IP_DST:
2553                 case O_TCPSEQ:
2554                 case O_TCPACK:
2555                 case O_PROB:
2556                 case O_ICMPTYPE:
2557                         if (cmdlen != F_INSN_SIZE(ipfw_insn_u32))
2558                                 goto bad_size;
2559                         break;
2560
2561                 case O_LIMIT:
2562                         if (cmdlen != F_INSN_SIZE(ipfw_insn_limit))
2563                                 goto bad_size;
2564                         break;
2565
2566                 case O_LOG:
2567                         if (cmdlen != F_INSN_SIZE(ipfw_insn_log))
2568                                 goto bad_size;
2569
2570                         ((ipfw_insn_log *)cmd)->log_left =
2571                             ((ipfw_insn_log *)cmd)->max_log;
2572
2573                         break;
2574
2575                 case O_IP_SRC_MASK:
2576                 case O_IP_DST_MASK:
2577                         if (cmdlen != F_INSN_SIZE(ipfw_insn_ip))
2578                                 goto bad_size;
2579                         if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) {
2580                                 kprintf("ipfw: opcode %d, useless rule\n",
2581                                         cmd->opcode);
2582                                 return EINVAL;
2583                         }
2584                         break;
2585
2586                 case O_IP_SRC_SET:
2587                 case O_IP_DST_SET:
2588                         if (cmd->arg1 == 0 || cmd->arg1 > 256) {
2589                                 kprintf("ipfw: invalid set size %d\n",
2590                                         cmd->arg1);
2591                                 return EINVAL;
2592                         }
2593                         if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) +
2594                             (cmd->arg1+31)/32 )
2595                                 goto bad_size;
2596                         break;
2597
2598                 case O_MACADDR2:
2599                         if (cmdlen != F_INSN_SIZE(ipfw_insn_mac))
2600                                 goto bad_size;
2601                         break;
2602
2603                 case O_MAC_TYPE:
2604                 case O_IP_SRCPORT:
2605                 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */
2606                         if (cmdlen < 2 || cmdlen > 31)
2607                                 goto bad_size;
2608                         break;
2609
2610                 case O_RECV:
2611                 case O_XMIT:
2612                 case O_VIA:
2613                         if (cmdlen != F_INSN_SIZE(ipfw_insn_if))
2614                                 goto bad_size;
2615                         break;
2616
2617                 case O_PIPE:
2618                 case O_QUEUE:
2619                         if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe))
2620                                 goto bad_size;
2621                         goto check_action;
2622
2623                 case O_FORWARD_IP:
2624                         if (cmdlen != F_INSN_SIZE(ipfw_insn_sa))
2625                                 goto bad_size;
2626                         goto check_action;
2627
2628                 case O_FORWARD_MAC: /* XXX not implemented yet */
2629                 case O_CHECK_STATE:
2630                 case O_COUNT:
2631                 case O_ACCEPT:
2632                 case O_DENY:
2633                 case O_REJECT:
2634                 case O_SKIPTO:
2635                 case O_DIVERT:
2636                 case O_TEE:
2637                         if (cmdlen != F_INSN_SIZE(ipfw_insn))
2638                                 goto bad_size;
2639 check_action:
2640                         if (have_action) {
2641                                 kprintf("ipfw: opcode %d, multiple actions"
2642                                         " not allowed\n",
2643                                         cmd->opcode);
2644                                 return EINVAL;
2645                         }
2646                         have_action = 1;
2647                         if (l != cmdlen) {
2648                                 kprintf("ipfw: opcode %d, action must be"
2649                                         " last opcode\n",
2650                                         cmd->opcode);
2651                                 return EINVAL;
2652                         }
2653                         break;
2654                 default:
2655                         kprintf("ipfw: opcode %d, unknown opcode\n",
2656                                 cmd->opcode);
2657                         return EINVAL;
2658                 }
2659         }
2660         if (have_action == 0) {
2661                 kprintf("ipfw: missing action\n");
2662                 return EINVAL;
2663         }
2664         return 0;
2665
2666 bad_size:
2667         kprintf("ipfw: opcode %d size %d wrong\n",
2668                 cmd->opcode, cmdlen);
2669         return EINVAL;
2670 }
2671
2672 static int
2673 ipfw_ctl_add_rule(struct sockopt *sopt)
2674 {
2675         struct ipfw_ioc_rule *ioc_rule;
2676         size_t size;
2677         int error;
2678
2679         size = sopt->sopt_valsize;
2680         if (size > (sizeof(uint32_t) * IPFW_RULE_SIZE_MAX) ||
2681             size < sizeof(*ioc_rule)) {
2682                 return EINVAL;
2683         }
2684         if (size != (sizeof(uint32_t) * IPFW_RULE_SIZE_MAX)) {
2685                 sopt->sopt_val = krealloc(sopt->sopt_val, sizeof(uint32_t) *
2686                                           IPFW_RULE_SIZE_MAX, M_TEMP, M_WAITOK);
2687         }
2688         ioc_rule = sopt->sopt_val;
2689
2690         error = ipfw_ctl_check_rule(ioc_rule, size);
2691         if (error)
2692                 return error;
2693
2694         error = ipfw_add_rule(&layer3_chain, ioc_rule);
2695         if (error)
2696                 return error;
2697
2698         if (sopt->sopt_dir == SOPT_GET)
2699                 sopt->sopt_valsize = IOC_RULESIZE(ioc_rule);
2700         return 0;
2701 }
2702
2703 static void *
2704 ipfw_copy_rule(const struct ip_fw *rule, struct ipfw_ioc_rule *ioc_rule)
2705 {
2706         ioc_rule->act_ofs = rule->act_ofs;
2707         ioc_rule->cmd_len = rule->cmd_len;
2708         ioc_rule->rulenum = rule->rulenum;
2709         ioc_rule->set = rule->set;
2710         ioc_rule->usr_flags = rule->usr_flags;
2711
2712         ioc_rule->set_disable = set_disable;
2713         ioc_rule->static_count = static_count;
2714         ioc_rule->static_len = static_ioc_len;
2715
2716         ioc_rule->pcnt = rule->pcnt;
2717         ioc_rule->bcnt = rule->bcnt;
2718         ioc_rule->timestamp = rule->timestamp;
2719
2720         bcopy(rule->cmd, ioc_rule->cmd, ioc_rule->cmd_len * 4 /* XXX */);
2721
2722         return ((uint8_t *)ioc_rule + IOC_RULESIZE(ioc_rule));
2723 }
2724
2725 static void
2726 ipfw_copy_state(const ipfw_dyn_rule *dyn_rule,
2727                 struct ipfw_ioc_state *ioc_state)
2728 {
2729         const struct ipfw_flow_id *id;
2730         struct ipfw_ioc_flowid *ioc_id;
2731
2732         ioc_state->expire = TIME_LEQ(dyn_rule->expire, time_second) ?
2733                             0 : dyn_rule->expire - time_second;
2734         ioc_state->pcnt = dyn_rule->pcnt;
2735         ioc_state->bcnt = dyn_rule->bcnt;
2736
2737         ioc_state->dyn_type = dyn_rule->dyn_type;
2738         ioc_state->count = dyn_rule->count;
2739
2740         ioc_state->rulenum = dyn_rule->rule->rulenum;
2741
2742         id = &dyn_rule->id;
2743         ioc_id = &ioc_state->id;
2744
2745         ioc_id->type = ETHERTYPE_IP;
2746         ioc_id->u.ip.dst_ip = id->dst_ip;
2747         ioc_id->u.ip.src_ip = id->src_ip;
2748         ioc_id->u.ip.dst_port = id->dst_port;
2749         ioc_id->u.ip.src_port = id->src_port;
2750         ioc_id->u.ip.proto = id->proto;
2751 }
2752
2753 static int
2754 ipfw_ctl_get_rules(struct sockopt *sopt)
2755 {
2756         struct ip_fw *rule;
2757         void *bp;
2758         size_t size;
2759
2760         /*
2761          * pass up a copy of the current rules. Static rules
2762          * come first (the last of which has number IPFW_DEFAULT_RULE),
2763          * followed by a possibly empty list of dynamic rule.
2764          */
2765         crit_enter();
2766
2767         size = static_ioc_len;  /* size of static rules */
2768         if (ipfw_dyn_v)         /* add size of dyn.rules */
2769                 size += (dyn_count * sizeof(struct ipfw_ioc_state));
2770
2771         if (sopt->sopt_valsize < size) {
2772                 /* short length, no need to return incomplete rules */
2773                 /* XXX: if superuser, no need to zero buffer */
2774                 bzero(sopt->sopt_val, sopt->sopt_valsize);
2775                 return 0;
2776         }
2777         bp = sopt->sopt_val;
2778
2779         for (rule = layer3_chain; rule; rule = rule->next)
2780                 bp = ipfw_copy_rule(rule, bp);
2781
2782         if (ipfw_dyn_v) {
2783                 struct ipfw_ioc_state *ioc_state;
2784                 int i;
2785
2786                 ioc_state = bp;
2787                 for (i = 0; i < curr_dyn_buckets; i++) {
2788                         ipfw_dyn_rule *p;
2789
2790                         for (p = ipfw_dyn_v[i]; p != NULL;
2791                              p = p->next, ioc_state++)
2792                                 ipfw_copy_state(p, ioc_state);
2793                 }
2794         }
2795
2796         crit_exit();
2797
2798         sopt->sopt_valsize = size;
2799         return 0;
2800 }
2801
2802 /**
2803  * {set|get}sockopt parser.
2804  */
2805 static int
2806 ipfw_ctl(struct sockopt *sopt)
2807 {
2808         int error, rulenum;
2809         uint32_t *masks;
2810         size_t size;
2811
2812         error = 0;
2813
2814         switch (sopt->sopt_name) {
2815         case IP_FW_GET:
2816                 error = ipfw_ctl_get_rules(sopt);
2817                 break;
2818
2819         case IP_FW_FLUSH:
2820                 /*
2821                  * Normally we cannot release the lock on each iteration.
2822                  * We could do it here only because we start from the head all
2823                  * the times so there is no risk of missing some entries.
2824                  * On the other hand, the risk is that we end up with
2825                  * a very inconsistent ruleset, so better keep the lock
2826                  * around the whole cycle.
2827                  *
2828                  * XXX this code can be improved by resetting the head of
2829                  * the list to point to the default rule, and then freeing
2830                  * the old list without the need for a lock.
2831                  */
2832
2833                 crit_enter();
2834                 free_chain(&layer3_chain, 0 /* keep default rule */);
2835                 crit_exit();
2836                 break;
2837
2838         case IP_FW_ADD:
2839                 error = ipfw_ctl_add_rule(sopt);
2840                 break;
2841
2842         case IP_FW_DEL:
2843                 /*
2844                  * IP_FW_DEL is used for deleting single rules or sets,
2845                  * and (ab)used to atomically manipulate sets. Argument size
2846                  * is used to distinguish between the two:
2847                  *    sizeof(uint32_t)
2848                  *      delete single rule or set of rules,
2849                  *      or reassign rules (or sets) to a different set.
2850                  *    2*sizeof(uint32_t)
2851                  *      atomic disable/enable sets.
2852                  *      first uint32_t contains sets to be disabled,
2853                  *      second uint32_t contains sets to be enabled.
2854                  */
2855                 masks = sopt->sopt_val;
2856                 size = sopt->sopt_valsize;
2857                 if (size == sizeof(*masks)) {
2858                         /*
2859                          * Delete or reassign static rule
2860                          */
2861                         error = del_entry(&layer3_chain, masks[0]);
2862                 } else if (size == (2 * sizeof(*masks))) {
2863                         /*
2864                          * Set enable/disable
2865                          */
2866                         crit_enter();
2867
2868                         set_disable =
2869                             (set_disable | masks[0]) & ~masks[1] &
2870                             ~(1 << 31); /* set 31 always enabled */
2871
2872                         crit_exit();
2873                 } else {
2874                         error = EINVAL;
2875                 }
2876                 break;
2877
2878         case IP_FW_ZERO:
2879         case IP_FW_RESETLOG: /* argument is an int, the rule number */
2880                 rulenum=0;
2881
2882                 if (sopt->sopt_val != 0) {
2883                     error = soopt_to_kbuf(sopt, &rulenum,
2884                             sizeof(int), sizeof(int));
2885                     if (error)
2886                         break;
2887                 }
2888                 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG);
2889                 break;
2890
2891         default:
2892                 kprintf("ipfw_ctl invalid option %d\n", sopt->sopt_name);
2893                 error = EINVAL;
2894         }
2895         return error;
2896 }
2897
2898 /*
2899  * This procedure is only used to handle keepalives. It is invoked
2900  * every dyn_keepalive_period
2901  */
2902 static void
2903 ipfw_tick(void *unused __unused)
2904 {
2905         int i;
2906         ipfw_dyn_rule *q;
2907
2908         if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0)
2909                 goto done;
2910
2911         crit_enter();
2912         for (i = 0; i < curr_dyn_buckets; i++) {
2913                 for (q = ipfw_dyn_v[i]; q; q = q->next) {
2914                         if (q->dyn_type == O_LIMIT_PARENT)
2915                                 continue;
2916                         if (q->id.proto != IPPROTO_TCP)
2917                                 continue;
2918                         if ((q->state & BOTH_SYN) != BOTH_SYN)
2919                                 continue;
2920                         if (TIME_LEQ(time_second + dyn_keepalive_interval,
2921                             q->expire))
2922                                 continue;       /* too early */
2923                         if (TIME_LEQ(q->expire, time_second))
2924                                 continue;       /* too late, rule expired */
2925
2926                         send_pkt(&q->id, q->ack_rev - 1, q->ack_fwd, TH_SYN);
2927                         send_pkt(&q->id, q->ack_fwd - 1, q->ack_rev, 0);
2928                 }
2929         }
2930         crit_exit();
2931 done:
2932         callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz,
2933                       ipfw_tick, NULL);
2934 }
2935
2936 static void
2937 ipfw_init_default_rule(struct ip_fw **head)
2938 {
2939         struct ip_fw *def_rule;
2940
2941         KKASSERT(*head == NULL);
2942
2943         def_rule = kmalloc(sizeof(*def_rule), M_IPFW, M_WAITOK | M_ZERO);
2944
2945         def_rule->act_ofs = 0;
2946         def_rule->rulenum = IPFW_DEFAULT_RULE;
2947         def_rule->cmd_len = 1;
2948         def_rule->set = 31;
2949
2950         def_rule->cmd[0].len = 1;
2951 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
2952         def_rule->cmd[0].opcode = O_ACCEPT;
2953 #else
2954         def_rule->cmd[0].opcode = O_DENY;
2955 #endif
2956
2957         def_rule->refcnt = 1;
2958
2959         *head = def_rule;
2960         ipfw_inc_static_count(def_rule);
2961
2962         /* Install the default rule */
2963         ip_fw_default_rule = def_rule;
2964 }
2965
2966 static void
2967 ipfw_init_dispatch(struct netmsg *nmsg)
2968 {
2969         int error = 0;
2970
2971         crit_enter();
2972
2973         if (IPFW_LOADED) {
2974                 kprintf("IP firewall already loaded\n");
2975                 error = EEXIST;
2976                 goto reply;
2977         }
2978
2979         ip_fw_chk_ptr = ipfw_chk;
2980         ip_fw_ctl_ptr = ipfw_ctl;
2981         ip_fw_dn_io_ptr = ipfw_dummynet_io;
2982
2983         layer3_chain = NULL;
2984         ipfw_init_default_rule(&layer3_chain);
2985
2986         kprintf("ipfw2 initialized, divert %s, "
2987                 "rule-based forwarding enabled, default to %s, logging ",
2988 #ifdef IPDIVERT
2989                 "enabled",
2990 #else
2991                 "disabled",
2992 #endif
2993                 ip_fw_default_rule->cmd[0].opcode == O_ACCEPT ?
2994                 "accept" : "deny");
2995
2996 #ifdef IPFIREWALL_VERBOSE
2997         fw_verbose = 1;
2998 #endif
2999 #ifdef IPFIREWALL_VERBOSE_LIMIT
3000         verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
3001 #endif
3002         if (fw_verbose == 0) {
3003                 kprintf("disabled\n");
3004         } else if (verbose_limit == 0) {
3005                 kprintf("unlimited\n");
3006         } else {
3007                 kprintf("limited to %d packets/entry by default\n",
3008                         verbose_limit);
3009         }
3010         callout_init(&ipfw_timeout_h);
3011
3012         ip_fw_loaded = 1;
3013         callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL);
3014 reply:
3015         crit_exit();
3016         lwkt_replymsg(&nmsg->nm_lmsg, error);
3017 }
3018
3019 static int
3020 ipfw_init(void)
3021 {
3022         struct netmsg smsg;
3023
3024         netmsg_init(&smsg, &curthread->td_msgport, 0, ipfw_init_dispatch);
3025         return lwkt_domsg(cpu_portfn(0), &smsg.nm_lmsg, 0);
3026 }
3027
3028 #ifdef KLD_MODULE
3029
3030 static void
3031 ipfw_fini_dispatch(struct netmsg *nmsg)
3032 {
3033         int error = 0;
3034
3035         crit_enter();
3036
3037         if (ipfw_refcnt != 0) {
3038                 error = EBUSY;
3039                 goto reply;
3040         }
3041
3042         callout_stop(&ipfw_timeout_h);
3043
3044         ip_fw_loaded = 0;
3045         netmsg_service_sync();
3046
3047         ip_fw_chk_ptr = NULL;
3048         ip_fw_ctl_ptr = NULL;
3049         ip_fw_dn_io_ptr = NULL;
3050         free_chain(&layer3_chain, 1 /* kill default rule */);
3051
3052         kprintf("IP firewall unloaded\n");
3053 reply:
3054         crit_exit();
3055         lwkt_replymsg(&nmsg->nm_lmsg, error);
3056 }
3057
3058 static int
3059 ipfw_fini(void)
3060 {
3061         struct netmsg smsg;
3062
3063         netmsg_init(&smsg, &curthread->td_msgport, 0, ipfw_fini_dispatch);
3064         return lwkt_domsg(cpu_portfn(0), &smsg.nm_lmsg, 0);
3065 }
3066
3067 #endif  /* KLD_MODULE */
3068
3069 static int
3070 ipfw_modevent(module_t mod, int type, void *unused)
3071 {
3072         int err = 0;
3073
3074         switch (type) {
3075         case MOD_LOAD:
3076                 err = ipfw_init();
3077                 break;
3078
3079         case MOD_UNLOAD:
3080 #ifndef KLD_MODULE
3081                 kprintf("ipfw statically compiled, cannot unload\n");
3082                 err = EBUSY;
3083 #else
3084                 err = ipfw_fini();
3085 #endif
3086                 break;
3087         default:
3088                 break;
3089         }
3090         return err;
3091 }
3092
3093 static moduledata_t ipfwmod = {
3094         "ipfw",
3095         ipfw_modevent,
3096         0
3097 };
3098 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_END, SI_ORDER_ANY);
3099 MODULE_VERSION(ipfw, 1);