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 1.44 2008/06/21 06:47:29 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 #include <net/if.h>
  60 #include <net/route.h>
  61 #include <netinet/in.h>
  62 #include <netinet/in_systm.h>
  63 #include <netinet/in_var.h>
  64 #include <netinet/in_pcb.h>
  65 #include <netinet/ip.h>
  66 #include <netinet/ip_var.h>
  67 #include <netinet/ip_icmp.h>
  68 #include "ip_fw.h"
  69 #include <net/dummynet/ip_dummynet.h>
  70 #include <netinet/tcp.h>
  71 #include <netinet/tcp_timer.h>
  72 #include <netinet/tcp_var.h>
  73 #include <netinet/tcpip.h>
  74 #include <netinet/udp.h>
  75 #include <netinet/udp_var.h>
  76
  77 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */
  78
  79 /*
  80  * set_disable contains one bit per set value (0..31).
  81  * If the bit is set, all rules with the corresponding set
  82  * are disabled. Set 31 is reserved for the default rule
  83  * and CANNOT be disabled.
  84  */
  85 static uint32_t set_disable;
  86
  87 static int fw_verbose;
  88 static int verbose_limit;
  89
  90 #ifdef KLD_MODULE
  91 static int ipfw_refcnt;
  92 #endif
  93
  94 static struct callout ipfw_timeout_h;
  95 #define IPFW_DEFAULT_RULE       65535
  96
  97 /*
  98  * list of rules for layer 3
  99  */
 100 static struct ip_fw *layer3_chain;
 101
 102 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");
 103
 104 static int fw_debug = 1;
 105 static int autoinc_step = 100; /* bounded to 1..1000 in ipfw_add_rule() */
 106
 107 #ifdef SYSCTL_NODE
 108 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
 109 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW,
 110     &fw_enable, 0, "Enable ipfw");
 111 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW,
 112     &autoinc_step, 0, "Rule number autincrement step");
 113 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW,
 114     &fw_one_pass, 0,
 115     "Only do a single pass through ipfw when using dummynet(4)");
 116 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW,
 117     &fw_debug, 0, "Enable printing of debug ip_fw statements");
 118 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW,
 119     &fw_verbose, 0, "Log matches to ipfw rules");
 120 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW,
 121     &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged");
 122
 123 /*
 124  * Description of dynamic rules.
 125  *
 126  * Dynamic rules are stored in lists accessed through a hash table
 127  * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
 128  * be modified through the sysctl variable dyn_buckets which is
 129  * updated when the table becomes empty.
 130  *
 131  * XXX currently there is only one list, ipfw_dyn.
 132  *
 133  * When a packet is received, its address fields are first masked
 134  * with the mask defined for the rule, then hashed, then matched
 135  * against the entries in the corresponding list.
 136  * Dynamic rules can be used for different purposes:
 137  *  + stateful rules;
 138  *  + enforcing limits on the number of sessions;
 139  *  + in-kernel NAT (not implemented yet)
 140  *
 141  * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
 142  * measured in seconds and depending on the flags.
 143  *
 144  * The total number of dynamic rules is stored in dyn_count.
 145  * The max number of dynamic rules is dyn_max. When we reach
 146  * the maximum number of rules we do not create anymore. This is
 147  * done to avoid consuming too much memory, but also too much
 148  * time when searching on each packet (ideally, we should try instead
 149  * to put a limit on the length of the list on each bucket...).
 150  *
 151  * Each dynamic rule holds a pointer to the parent ipfw rule so
 152  * we know what action to perform. Dynamic rules are removed when
 153  * the parent rule is deleted. XXX we should make them survive.
 154  *
 155  * There are some limitations with dynamic rules -- we do not
 156  * obey the 'randomized match', and we do not do multiple
 157  * passes through the firewall. XXX check the latter!!!
 158  */
 159 static ipfw_dyn_rule **ipfw_dyn_v = NULL;
 160 static uint32_t dyn_buckets = 256; /* must be power of 2 */
 161 static uint32_t curr_dyn_buckets = 256; /* must be power of 2 */
 162
 163 /*
 164  * Timeouts for various events in handing dynamic rules.
 165  */
 166 static uint32_t dyn_ack_lifetime = 300;
 167 static uint32_t dyn_syn_lifetime = 20;
 168 static uint32_t dyn_fin_lifetime = 1;
 169 static uint32_t dyn_rst_lifetime = 1;
 170 static uint32_t dyn_udp_lifetime = 10;
 171 static uint32_t dyn_short_lifetime = 5;
 172
 173 /*
 174  * Keepalives are sent if dyn_keepalive is set. They are sent every
 175  * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
 176  * seconds of lifetime of a rule.
 177  * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
 178  * than dyn_keepalive_period.
 179  */
 180
 181 static uint32_t dyn_keepalive_interval = 20;
 182 static uint32_t dyn_keepalive_period = 5;
 183 static uint32_t dyn_keepalive = 1;      /* do send keepalives */
 184
 185 static uint32_t static_count;           /* # of static rules */
 186 static uint32_t static_ioc_len; /* bytes of static rules */
 187 static uint32_t dyn_count;              /* # of dynamic rules */
 188 static uint32_t dyn_max = 4096; /* max # of dynamic rules */
 189
 190 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW,
 191     &dyn_buckets, 0, "Number of dyn. buckets");
 192 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD,
 193     &curr_dyn_buckets, 0, "Current Number of dyn. buckets");
 194 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD,
 195     &dyn_count, 0, "Number of dyn. rules");
 196 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW,
 197     &dyn_max, 0, "Max number of dyn. rules");
 198 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD,
 199     &static_count, 0, "Number of static rules");
 200 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW,
 201     &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks");
 202 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW,
 203     &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn");
 204 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW,
 205     &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin");
 206 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW,
 207     &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst");
 208 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW,
 209     &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP");
 210 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW,
 211     &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations");
 212 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW,
 213     &dyn_keepalive, 0, "Enable keepalives for dyn. rules");
 214
 215 #endif /* SYSCTL_NODE */
 216
 217 /**
 218  * dummynet needs a reference to the default rule, because rules can be
 219  * deleted while packets hold a reference to them. When this happens,
 220  * dummynet changes the reference to the default rule (it could well be a
 221  * NULL pointer, but this way we do not need to check for the special
 222  * case, plus here he have info on the default behaviour).
 223  */
 224 struct ip_fw *ip_fw_default_rule;
 225
 226 static ip_fw_chk_t      ipfw_chk;
 227
 228 static __inline int
 229 ipfw_free_rule(struct ip_fw *rule)
 230 {
 231         KASSERT(rule->refcnt > 0, ("invalid refcnt %u\n", rule->refcnt));
 232         atomic_subtract_int(&rule->refcnt, 1);
 233         if (atomic_cmpset_int(&rule->refcnt, 0, 1)) {
 234                 kfree(rule, M_IPFW);
 235                 return 1;
 236         }
 237         return 0;
 238 }
 239
 240 static void
 241 ipfw_unref_rule(void *priv)
 242 {
 243         ipfw_free_rule(priv);
 244 #ifdef KLD_MODULE
 245         atomic_subtract_int(&ipfw_refcnt, 1);
 246 #endif
 247 }
 248
 249 static __inline void
 250 ipfw_ref_rule(struct ip_fw *rule)
 251 {
 252 #ifdef KLD_MODULE
 253         atomic_add_int(&ipfw_refcnt, 1);
 254 #endif
 255         atomic_add_int(&rule->refcnt, 1);
 256 }
 257
 258 /*
 259  * This macro maps an ip pointer into a layer3 header pointer of type T
 260  */
 261 #define L3HDR(T, ip) ((T *)((uint32_t *)(ip) + (ip)->ip_hl))
 262
 263 static __inline int
 264 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd)
 265 {
 266         int type = L3HDR(struct icmp,ip)->icmp_type;
 267
 268         return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) );
 269 }
 270
 271 #define TT      ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \
 272     (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) )
 273
 274 static int
 275 is_icmp_query(struct ip *ip)
 276 {
 277         int type = L3HDR(struct icmp, ip)->icmp_type;
 278         return (type <= ICMP_MAXTYPE && (TT & (1<<type)) );
 279 }
 280 #undef TT
 281
 282 /*
 283  * The following checks use two arrays of 8 or 16 bits to store the
 284  * bits that we want set or clear, respectively. They are in the
 285  * low and high half of cmd->arg1 or cmd->d[0].
 286  *
 287  * We scan options and store the bits we find set. We succeed if
 288  *
 289  *      (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear
 290  *
 291  * The code is sometimes optimized not to store additional variables.
 292  */
 293
 294 static int
 295 flags_match(ipfw_insn *cmd, uint8_t bits)
 296 {
 297         u_char want_clear;
 298         bits = ~bits;
 299
 300         if ( ((cmd->arg1 & 0xff) & bits) != 0)
 301                 return 0; /* some bits we want set were clear */
 302         want_clear = (cmd->arg1 >> 8) & 0xff;
 303         if ( (want_clear & bits) != want_clear)
 304                 return 0; /* some bits we want clear were set */
 305         return 1;
 306 }
 307
 308 static int
 309 ipopts_match(struct ip *ip, ipfw_insn *cmd)
 310 {
 311         int optlen, bits = 0;
 312         u_char *cp = (u_char *)(ip + 1);
 313         int x = (ip->ip_hl << 2) - sizeof (struct ip);
 314
 315         for (; x > 0; x -= optlen, cp += optlen) {
 316                 int opt = cp[IPOPT_OPTVAL];
 317
 318                 if (opt == IPOPT_EOL)
 319                         break;
 320                 if (opt == IPOPT_NOP)
 321                         optlen = 1;
 322                 else {
 323                         optlen = cp[IPOPT_OLEN];
 324                         if (optlen <= 0 || optlen > x)
 325                                 return 0; /* invalid or truncated */
 326                 }
 327                 switch (opt) {
 328
 329                 default:
 330                         break;
 331
 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         }
 349         return (flags_match(cmd, bits));
 350 }
 351
 352 static int
 353 tcpopts_match(struct ip *ip, ipfw_insn *cmd)
 354 {
 355         int optlen, bits = 0;
 356         struct tcphdr *tcp = L3HDR(struct tcphdr,ip);
 357         u_char *cp = (u_char *)(tcp + 1);
 358         int x = (tcp->th_off << 2) - sizeof(struct tcphdr);
 359
 360         for (; x > 0; x -= optlen, cp += optlen) {
 361                 int opt = cp[0];
 362                 if (opt == TCPOPT_EOL)
 363                         break;
 364                 if (opt == TCPOPT_NOP)
 365                         optlen = 1;
 366                 else {
 367                         optlen = cp[1];
 368                         if (optlen <= 0)
 369                                 break;
 370                 }
 371
 372                 switch (opt) {
 373
 374                 default:
 375                         break;
 376
 377                 case TCPOPT_MAXSEG:
 378                         bits |= IP_FW_TCPOPT_MSS;
 379                         break;
 380
 381                 case TCPOPT_WINDOW:
 382                         bits |= IP_FW_TCPOPT_WINDOW;
 383                         break;
 384
 385                 case TCPOPT_SACK_PERMITTED:
 386                 case TCPOPT_SACK:
 387                         bits |= IP_FW_TCPOPT_SACK;
 388                         break;
 389
 390                 case TCPOPT_TIMESTAMP:
 391                         bits |= IP_FW_TCPOPT_TS;
 392                         break;
 393
 394                 case TCPOPT_CC:
 395                 case TCPOPT_CCNEW:
 396                 case TCPOPT_CCECHO:
 397                         bits |= IP_FW_TCPOPT_CC;
 398                         break;
 399                 }
 400         }
 401         return (flags_match(cmd, bits));
 402 }
 403
 404 static int
 405 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd)
 406 {
 407         if (ifp == NULL)        /* no iface with this packet, match fails */
 408                 return 0;
 409         /* Check by name or by IP address */
 410         if (cmd->name[0] != '\0') { /* match by name */
 411                 /* Check name */
 412                 if (cmd->p.glob) {
 413                         if (kfnmatch(cmd->name, ifp->if_xname, 0) == 0)
 414                                 return(1);
 415                 } else {
 416                         if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0)
 417                                 return(1);
 418                 }
 419         } else {
 420                 struct ifaddr_container *ifac;
 421
 422                 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 423                         struct ifaddr *ia = ifac->ifa;
 424
 425                         if (ia->ifa_addr == NULL)
 426                                 continue;
 427                         if (ia->ifa_addr->sa_family != AF_INET)
 428                                 continue;
 429                         if (cmd->p.ip.s_addr == ((struct sockaddr_in *)
 430                             (ia->ifa_addr))->sin_addr.s_addr)
 431                                 return(1);      /* match */
 432                 }
 433         }
 434         return(0);      /* no match, fail ... */
 435 }
 436
 437 static uint64_t norule_counter; /* counter for ipfw_log(NULL...) */
 438
 439 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0
 440 #define SNP(buf) buf, sizeof(buf)
 441
 442 /*
 443  * We enter here when we have a rule with O_LOG.
 444  * XXX this function alone takes about 2Kbytes of code!
 445  */
 446 static void
 447 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh,
 448         struct mbuf *m, struct ifnet *oif)
 449 {
 450         char *action;
 451         int limit_reached = 0;
 452         char action2[40], proto[48], fragment[28];
 453
 454         fragment[0] = '\0';
 455         proto[0] = '\0';
 456
 457         if (f == NULL) {        /* bogus pkt */
 458                 if (verbose_limit != 0 && norule_counter >= verbose_limit)
 459                         return;
 460                 norule_counter++;
 461                 if (norule_counter == verbose_limit)
 462                         limit_reached = verbose_limit;
 463                 action = "Refuse";
 464         } else {        /* O_LOG is the first action, find the real one */
 465                 ipfw_insn *cmd = ACTION_PTR(f);
 466                 ipfw_insn_log *l = (ipfw_insn_log *)cmd;
 467
 468                 if (l->max_log != 0 && l->log_left == 0)
 469                         return;
 470                 l->log_left--;
 471                 if (l->log_left == 0)
 472                         limit_reached = l->max_log;
 473                 cmd += F_LEN(cmd);      /* point to first action */
 474                 if (cmd->opcode == O_PROB)
 475                         cmd += F_LEN(cmd);
 476
 477                 action = action2;
 478                 switch (cmd->opcode) {
 479                 case O_DENY:
 480                         action = "Deny";
 481                         break;
 482
 483                 case O_REJECT:
 484                         if (cmd->arg1==ICMP_REJECT_RST)
 485                                 action = "Reset";
 486                         else if (cmd->arg1==ICMP_UNREACH_HOST)
 487                                 action = "Reject";
 488                         else
 489                                 ksnprintf(SNPARGS(action2, 0), "Unreach %d",
 490                                         cmd->arg1);
 491                         break;
 492
 493                 case O_ACCEPT:
 494                         action = "Accept";
 495                         break;
 496                 case O_COUNT:
 497                         action = "Count";
 498                         break;
 499                 case O_DIVERT:
 500                         ksnprintf(SNPARGS(action2, 0), "Divert %d",
 501                                 cmd->arg1);
 502                         break;
 503                 case O_TEE:
 504                         ksnprintf(SNPARGS(action2, 0), "Tee %d",
 505                                 cmd->arg1);
 506                         break;
 507                 case O_SKIPTO:
 508                         ksnprintf(SNPARGS(action2, 0), "SkipTo %d",
 509                                 cmd->arg1);
 510                         break;
 511                 case O_PIPE:
 512                         ksnprintf(SNPARGS(action2, 0), "Pipe %d",
 513                                 cmd->arg1);
 514                         break;
 515                 case O_QUEUE:
 516                         ksnprintf(SNPARGS(action2, 0), "Queue %d",
 517                                 cmd->arg1);
 518                         break;
 519                 case O_FORWARD_IP: {
 520                         ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd;
 521                         int len;
 522
 523                         len = ksnprintf(SNPARGS(action2, 0), "Forward to %s",
 524                                 inet_ntoa(sa->sa.sin_addr));
 525                         if (sa->sa.sin_port)
 526                                 ksnprintf(SNPARGS(action2, len), ":%d",
 527                                     sa->sa.sin_port);
 528                         }
 529                         break;
 530                 default:
 531                         action = "UNKNOWN";
 532                         break;
 533                 }
 534         }
 535
 536         if (hlen == 0) {        /* non-ip */
 537                 ksnprintf(SNPARGS(proto, 0), "MAC");
 538         } else {
 539                 struct ip *ip = mtod(m, struct ip *);
 540                 /* these three are all aliases to the same thing */
 541                 struct icmp *const icmp = L3HDR(struct icmp, ip);
 542                 struct tcphdr *const tcp = (struct tcphdr *)icmp;
 543                 struct udphdr *const udp = (struct udphdr *)icmp;
 544
 545                 int ip_off, offset, ip_len;
 546
 547                 int len;
 548
 549                 if (eh != NULL) { /* layer 2 packets are as on the wire */
 550                         ip_off = ntohs(ip->ip_off);
 551                         ip_len = ntohs(ip->ip_len);
 552                 } else {
 553                         ip_off = ip->ip_off;
 554                         ip_len = ip->ip_len;
 555                 }
 556                 offset = ip_off & IP_OFFMASK;
 557                 switch (ip->ip_p) {
 558                 case IPPROTO_TCP:
 559                         len = ksnprintf(SNPARGS(proto, 0), "TCP %s",
 560                             inet_ntoa(ip->ip_src));
 561                         if (offset == 0)
 562                                 ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
 563                                     ntohs(tcp->th_sport),
 564                                     inet_ntoa(ip->ip_dst),
 565                                     ntohs(tcp->th_dport));
 566                         else
 567                                 ksnprintf(SNPARGS(proto, len), " %s",
 568                                     inet_ntoa(ip->ip_dst));
 569                         break;
 570
 571                 case IPPROTO_UDP:
 572                         len = ksnprintf(SNPARGS(proto, 0), "UDP %s",
 573                                 inet_ntoa(ip->ip_src));
 574                         if (offset == 0)
 575                                 ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
 576                                     ntohs(udp->uh_sport),
 577                                     inet_ntoa(ip->ip_dst),
 578                                     ntohs(udp->uh_dport));
 579                         else
 580                                 ksnprintf(SNPARGS(proto, len), " %s",
 581                                     inet_ntoa(ip->ip_dst));
 582                         break;
 583
 584                 case IPPROTO_ICMP:
 585                         if (offset == 0)
 586                                 len = ksnprintf(SNPARGS(proto, 0),
 587                                     "ICMP:%u.%u ",
 588                                     icmp->icmp_type, icmp->icmp_code);
 589                         else
 590                                 len = ksnprintf(SNPARGS(proto, 0), "ICMP ");
 591                         len += ksnprintf(SNPARGS(proto, len), "%s",
 592                             inet_ntoa(ip->ip_src));
 593                         ksnprintf(SNPARGS(proto, len), " %s",
 594                             inet_ntoa(ip->ip_dst));
 595                         break;
 596
 597                 default:
 598                         len = ksnprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p,
 599                             inet_ntoa(ip->ip_src));
 600                         ksnprintf(SNPARGS(proto, len), " %s",
 601                             inet_ntoa(ip->ip_dst));
 602                         break;
 603                 }
 604
 605                 if (ip_off & (IP_MF | IP_OFFMASK))
 606                         ksnprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)",
 607                              ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2),
 608                              offset << 3,
 609                              (ip_off & IP_MF) ? "+" : "");
 610         }
 611         if (oif || m->m_pkthdr.rcvif)
 612                 log(LOG_SECURITY | LOG_INFO,
 613                     "ipfw: %d %s %s %s via %s%s\n",
 614                     f ? f->rulenum : -1,
 615                     action, proto, oif ? "out" : "in",
 616                     oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname,
 617                     fragment);
 618         else
 619                 log(LOG_SECURITY | LOG_INFO,
 620                     "ipfw: %d %s %s [no if info]%s\n",
 621                     f ? f->rulenum : -1,
 622                     action, proto, fragment);
 623         if (limit_reached)
 624                 log(LOG_SECURITY | LOG_NOTICE,
 625                     "ipfw: limit %d reached on entry %d\n",
 626                     limit_reached, f ? f->rulenum : -1);
 627 }
 628
 629 /*
 630  * IMPORTANT: the hash function for dynamic rules must be commutative
 631  * in source and destination (ip,port), because rules are bidirectional
 632  * and we want to find both in the same bucket.
 633  */
 634 static __inline int
 635 hash_packet(struct ipfw_flow_id *id)
 636 {
 637         uint32_t i;
 638
 639         i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
 640         i &= (curr_dyn_buckets - 1);
 641         return i;
 642 }
 643
 644 /**
 645  * unlink a dynamic rule from a chain. prev is a pointer to
 646  * the previous one, q is a pointer to the rule to delete,
 647  * head is a pointer to the head of the queue.
 648  * Modifies q and potentially also head.
 649  */
 650 #define UNLINK_DYN_RULE(prev, head, q) {                                \
 651         ipfw_dyn_rule *old_q = q;                                       \
 652                                                                         \
 653         /* remove a refcount to the parent */                           \
 654         if (q->dyn_type == O_LIMIT)                                     \
 655                 q->parent->count--;                                     \
 656         DEB(kprintf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n",        \
 657                 (q->id.src_ip), (q->id.src_port),                       \
 658                 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); )      \
 659         if (prev != NULL)                                               \
 660                 prev->next = q = q->next;                               \
 661         else                                                            \
 662                 head = q = q->next;                                     \
 663         KASSERT(dyn_count > 0, ("invalid dyn count %u\n", dyn_count));  \
 664         dyn_count--;                                                    \
 665         kfree(old_q, M_IPFW); }
 666
 667 #define TIME_LEQ(a,b)       ((int)((a)-(b)) <= 0)
 668
 669 /**
 670  * Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
 671  *
 672  * If keep_me == NULL, rules are deleted even if not expired,
 673  * otherwise only expired rules are removed.
 674  *
 675  * The value of the second parameter is also used to point to identify
 676  * a rule we absolutely do not want to remove (e.g. because we are
 677  * holding a reference to it -- this is the case with O_LIMIT_PARENT
 678  * rules). The pointer is only used for comparison, so any non-null
 679  * value will do.
 680  */
 681 static void
 682 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
 683 {
 684         static uint32_t last_remove = 0;
 685
 686 #define FORCE (keep_me == NULL)
 687
 688         ipfw_dyn_rule *prev, *q;
 689         int i, pass = 0, max_pass = 0;
 690
 691         if (ipfw_dyn_v == NULL || dyn_count == 0)
 692                 return;
 693         /* do not expire more than once per second, it is useless */
 694         if (!FORCE && last_remove == time_second)
 695                 return;
 696         last_remove = time_second;
 697
 698         /*
 699          * because O_LIMIT refer to parent rules, during the first pass only
 700          * remove child and mark any pending LIMIT_PARENT, and remove
 701          * them in a second pass.
 702          */
 703 next_pass:
 704         for (i = 0 ; i < curr_dyn_buckets ; i++) {
 705                 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) {
 706                         /*
 707                          * Logic can become complex here, so we split tests.
 708                          */
 709                         if (q == keep_me)
 710                                 goto next;
 711                         if (rule != NULL && rule != q->rule)
 712                                 goto next; /* not the one we are looking for */
 713                         if (q->dyn_type == O_LIMIT_PARENT) {
 714                                 /*
 715                                  * handle parent in the second pass,
 716                                  * record we need one.
 717                                  */
 718                                 max_pass = 1;
 719                                 if (pass == 0)
 720                                         goto next;
 721                                 if (FORCE && q->count != 0 ) {
 722                                         /* XXX should not happen! */
 723                                         kprintf( "OUCH! cannot remove rule,"
 724                                              " count %d\n", q->count);
 725                                 }
 726                         } else {
 727                                 if (!FORCE &&
 728                                     !TIME_LEQ( q->expire, time_second ))
 729                                         goto next;
 730                         }
 731                         UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
 732                         continue;
 733 next:
 734                         prev=q;
 735                         q=q->next;
 736                 }
 737         }
 738         if (pass++ < max_pass)
 739                 goto next_pass;
 740 }
 741
 742
 743 /**
 744  * lookup a dynamic rule.
 745  */
 746 static ipfw_dyn_rule *
 747 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
 748         struct tcphdr *tcp)
 749 {
 750         /*
 751          * stateful ipfw extensions.
 752          * Lookup into dynamic session queue
 753          */
 754 #define MATCH_REVERSE   0
 755 #define MATCH_FORWARD   1
 756 #define MATCH_NONE      2
 757 #define MATCH_UNKNOWN   3
 758         int i, dir = MATCH_NONE;
 759         ipfw_dyn_rule *prev, *q=NULL;
 760
 761         if (ipfw_dyn_v == NULL)
 762                 goto done;      /* not found */
 763         i = hash_packet( pkt );
 764         for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) {
 765                 if (q->dyn_type == O_LIMIT_PARENT)
 766                         goto next;
 767                 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */
 768                         UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
 769                         continue;
 770                 }
 771                 if ( pkt->proto == q->id.proto) {
 772                         if (pkt->src_ip == q->id.src_ip &&
 773                             pkt->dst_ip == q->id.dst_ip &&
 774                             pkt->src_port == q->id.src_port &&
 775                             pkt->dst_port == q->id.dst_port ) {
 776                                 dir = MATCH_FORWARD;
 777                                 break;
 778                         }
 779                         if (pkt->src_ip == q->id.dst_ip &&
 780                             pkt->dst_ip == q->id.src_ip &&
 781                             pkt->src_port == q->id.dst_port &&
 782                             pkt->dst_port == q->id.src_port ) {
 783                                 dir = MATCH_REVERSE;
 784                                 break;
 785                         }
 786                 }
 787 next:
 788                 prev = q;
 789                 q = q->next;
 790         }
 791         if (q == NULL)
 792                 goto done; /* q = NULL, not found */
 793
 794         if ( prev != NULL) { /* found and not in front */
 795                 prev->next = q->next;
 796                 q->next = ipfw_dyn_v[i];
 797                 ipfw_dyn_v[i] = q;
 798         }
 799         if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
 800                 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST);
 801
 802 #define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
 803 #define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
 804                 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
 805                 switch (q->state) {
 806                 case TH_SYN:                            /* opening */
 807                         q->expire = time_second + dyn_syn_lifetime;
 808                         break;
 809
 810                 case BOTH_SYN:                  /* move to established */
 811                 case BOTH_SYN | TH_FIN :        /* one side tries to close */
 812                 case BOTH_SYN | (TH_FIN << 8) :
 813                         if (tcp) {
 814 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
 815                             uint32_t ack = ntohl(tcp->th_ack);
 816                             if (dir == MATCH_FORWARD) {
 817                                 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd))
 818                                     q->ack_fwd = ack;
 819                                 else { /* ignore out-of-sequence */
 820                                     break;
 821                                 }
 822                             } else {
 823                                 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev))
 824                                     q->ack_rev = ack;
 825                                 else { /* ignore out-of-sequence */
 826                                     break;
 827                                 }
 828                             }
 829                         }
 830                         q->expire = time_second + dyn_ack_lifetime;
 831                         break;
 832
 833                 case BOTH_SYN | BOTH_FIN:       /* both sides closed */
 834                         if (dyn_fin_lifetime >= dyn_keepalive_period)
 835                                 dyn_fin_lifetime = dyn_keepalive_period - 1;
 836                         q->expire = time_second + dyn_fin_lifetime;
 837                         break;
 838
 839                 default:
 840 #if 0
 841                         /*
 842                          * reset or some invalid combination, but can also
 843                          * occur if we use keep-state the wrong way.
 844                          */
 845                         if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
 846                                 kprintf("invalid state: 0x%x\n", q->state);
 847 #endif
 848                         if (dyn_rst_lifetime >= dyn_keepalive_period)
 849                                 dyn_rst_lifetime = dyn_keepalive_period - 1;
 850                         q->expire = time_second + dyn_rst_lifetime;
 851                         break;
 852                 }
 853         } else if (pkt->proto == IPPROTO_UDP) {
 854                 q->expire = time_second + dyn_udp_lifetime;
 855         } else {
 856                 /* other protocols */
 857                 q->expire = time_second + dyn_short_lifetime;
 858         }
 859 done:
 860         if (match_direction)
 861                 *match_direction = dir;
 862         return q;
 863 }
 864
 865 static void
 866 realloc_dynamic_table(void)
 867 {
 868         /*
 869          * Try reallocation, make sure we have a power of 2 and do
 870          * not allow more than 64k entries. In case of overflow,
 871          * default to 1024.
 872          */
 873
 874         if (dyn_buckets > 65536)
 875                 dyn_buckets = 1024;
 876         if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */
 877                 dyn_buckets = curr_dyn_buckets; /* reset */
 878                 return;
 879         }
 880         curr_dyn_buckets = dyn_buckets;
 881         if (ipfw_dyn_v != NULL)
 882                 kfree(ipfw_dyn_v, M_IPFW);
 883         for (;;) {
 884                 ipfw_dyn_v = kmalloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
 885                        M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
 886                 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2)
 887                         break;
 888                 curr_dyn_buckets /= 2;
 889         }
 890 }
 891
 892 /**
 893  * Install state of type 'type' for a dynamic session.
 894  * The hash table contains two type of rules:
 895  * - regular rules (O_KEEP_STATE)
 896  * - rules for sessions with limited number of sess per user
 897  *   (O_LIMIT). When they are created, the parent is
 898  *   increased by 1, and decreased on delete. In this case,
 899  *   the third parameter is the parent rule and not the chain.
 900  * - "parent" rules for the above (O_LIMIT_PARENT).
 901  */
 902 static ipfw_dyn_rule *
 903 add_dyn_rule(struct ipfw_flow_id *id, uint8_t dyn_type, struct ip_fw *rule)
 904 {
 905         ipfw_dyn_rule *r;
 906         int i;
 907
 908         if (ipfw_dyn_v == NULL ||
 909             (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) {
 910                 realloc_dynamic_table();
 911                 if (ipfw_dyn_v == NULL)
 912                         return NULL; /* failed ! */
 913         }
 914         i = hash_packet(id);
 915
 916         r = kmalloc(sizeof *r, M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
 917         if (r == NULL) {
 918                 kprintf ("sorry cannot allocate state\n");
 919                 return NULL;
 920         }
 921
 922         /* increase refcount on parent, and set pointer */
 923         if (dyn_type == O_LIMIT) {
 924                 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
 925                 if ( parent->dyn_type != O_LIMIT_PARENT)
 926                         panic("invalid parent");
 927                 parent->count++;
 928                 r->parent = parent;
 929                 rule = parent->rule;
 930         }
 931
 932         r->id = *id;
 933         r->expire = time_second + dyn_syn_lifetime;
 934         r->rule = rule;
 935         r->dyn_type = dyn_type;
 936         r->pcnt = r->bcnt = 0;
 937         r->count = 0;
 938
 939         r->bucket = i;
 940         r->next = ipfw_dyn_v[i];
 941         ipfw_dyn_v[i] = r;
 942         dyn_count++;
 943         DEB(kprintf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n",
 944            dyn_type,
 945            (r->id.src_ip), (r->id.src_port),
 946            (r->id.dst_ip), (r->id.dst_port),
 947            dyn_count ); )
 948         return r;
 949 }
 950
 951 /**
 952  * lookup dynamic parent rule using pkt and rule as search keys.
 953  * If the lookup fails, then install one.
 954  */
 955 static ipfw_dyn_rule *
 956 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
 957 {
 958         ipfw_dyn_rule *q;
 959         int i;
 960
 961         if (ipfw_dyn_v) {
 962                 i = hash_packet( pkt );
 963                 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next)
 964                         if (q->dyn_type == O_LIMIT_PARENT &&
 965                             rule== q->rule &&
 966                             pkt->proto == q->id.proto &&
 967                             pkt->src_ip == q->id.src_ip &&
 968                             pkt->dst_ip == q->id.dst_ip &&
 969                             pkt->src_port == q->id.src_port &&
 970                             pkt->dst_port == q->id.dst_port) {
 971                                 q->expire = time_second + dyn_short_lifetime;
 972                                 DEB(kprintf("lookup_dyn_parent found 0x%p\n",q);)
 973                                 return q;
 974                         }
 975         }
 976         return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
 977 }
 978
 979 /**
 980  * Install dynamic state for rule type cmd->o.opcode
 981  *
 982  * Returns 1 (failure) if state is not installed because of errors or because
 983  * session limitations are enforced.
 984  */
 985 static int
 986 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
 987         struct ip_fw_args *args)
 988 {
 989         static int last_log;
 990
 991         ipfw_dyn_rule *q;
 992
 993         DEB(kprintf("-- install state type %d 0x%08x %u -> 0x%08x %u\n",
 994             cmd->o.opcode,
 995             (args->f_id.src_ip), (args->f_id.src_port),
 996             (args->f_id.dst_ip), (args->f_id.dst_port) );)
 997
 998         q = lookup_dyn_rule(&args->f_id, NULL, NULL);
 999
1000         if (q != NULL) { /* should never occur */
1001                 if (last_log != time_second) {
1002                         last_log = time_second;
1003                         kprintf(" install_state: entry already present, done\n");
1004                 }
1005                 return 0;
1006         }
1007
1008         if (dyn_count >= dyn_max)
1009                 /*
1010                  * Run out of slots, try to remove any expired rule.
1011                  */
1012                 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);
1013
1014         if (dyn_count >= dyn_max) {
1015                 if (last_log != time_second) {
1016                         last_log = time_second;
1017                         kprintf("install_state: Too many dynamic rules\n");
1018                 }
1019                 return 1; /* cannot install, notify caller */
1020         }
1021
1022         switch (cmd->o.opcode) {
1023         case O_KEEP_STATE: /* bidir rule */
1024                 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
1025                 break;
1026
1027         case O_LIMIT: /* limit number of sessions */
1028             {
1029                 uint16_t limit_mask = cmd->limit_mask;
1030                 struct ipfw_flow_id id;
1031                 ipfw_dyn_rule *parent;
1032
1033                 DEB(kprintf("installing dyn-limit rule %d\n", cmd->conn_limit);)
1034
1035                 id.dst_ip = id.src_ip = 0;
1036                 id.dst_port = id.src_port = 0;
1037                 id.proto = args->f_id.proto;
1038
1039                 if (limit_mask & DYN_SRC_ADDR)
1040                         id.src_ip = args->f_id.src_ip;
1041                 if (limit_mask & DYN_DST_ADDR)
1042                         id.dst_ip = args->f_id.dst_ip;
1043                 if (limit_mask & DYN_SRC_PORT)
1044                         id.src_port = args->f_id.src_port;
1045                 if (limit_mask & DYN_DST_PORT)
1046                         id.dst_port = args->f_id.dst_port;
1047                 parent = lookup_dyn_parent(&id, rule);
1048                 if (parent == NULL) {
1049                         kprintf("add parent failed\n");
1050                         return 1;
1051                 }
1052                 if (parent->count >= cmd->conn_limit) {
1053                         /*
1054                          * See if we can remove some expired rule.
1055                          */
1056                         remove_dyn_rule(rule, parent);
1057                         if (parent->count >= cmd->conn_limit) {
1058                                 if (fw_verbose && last_log != time_second) {
1059                                         last_log = time_second;
1060                                         log(LOG_SECURITY | LOG_DEBUG,
1061                                             "drop session, too many entries\n");
1062                                 }
1063                                 return 1;
1064                         }
1065                 }
1066                 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent);
1067             }
1068                 break;
1069         default:
1070                 kprintf("unknown dynamic rule type %u\n", cmd->o.opcode);
1071                 return 1;
1072         }
1073         lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */
1074         return 0;
1075 }
1076
1077 /*
1078  * Transmit a TCP packet, containing either a RST or a keepalive.
1079  * When flags & TH_RST, we are sending a RST packet, because of a
1080  * "reset" action matched the packet.
1081  * Otherwise we are sending a keepalive, and flags & TH_
1082  */
1083 static void
1084 send_pkt(struct ipfw_flow_id *id, uint32_t seq, uint32_t ack, int flags)
1085 {
1086         struct mbuf *m;
1087         struct ip *ip;
1088         struct tcphdr *tcp;
1089         struct route sro;       /* fake route */
1090
1091         MGETHDR(m, MB_DONTWAIT, MT_HEADER);
1092         if (m == 0)
1093                 return;
1094         m->m_pkthdr.rcvif = (struct ifnet *)0;
1095         m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
1096         m->m_data += max_linkhdr;
1097
1098         ip = mtod(m, struct ip *);
1099         bzero(ip, m->m_len);
1100         tcp = (struct tcphdr *)(ip + 1); /* no IP options */
1101         ip->ip_p = IPPROTO_TCP;
1102         tcp->th_off = 5;
1103         /*
1104          * Assume we are sending a RST (or a keepalive in the reverse
1105          * direction), swap src and destination addresses and ports.
1106          */
1107         ip->ip_src.s_addr = htonl(id->dst_ip);
1108         ip->ip_dst.s_addr = htonl(id->src_ip);
1109         tcp->th_sport = htons(id->dst_port);
1110         tcp->th_dport = htons(id->src_port);
1111         if (flags & TH_RST) {   /* we are sending a RST */
1112                 if (flags & TH_ACK) {
1113                         tcp->th_seq = htonl(ack);
1114                         tcp->th_ack = htonl(0);
1115                         tcp->th_flags = TH_RST;
1116                 } else {
1117                         if (flags & TH_SYN)
1118                                 seq++;
1119                         tcp->th_seq = htonl(0);
1120                         tcp->th_ack = htonl(seq);
1121                         tcp->th_flags = TH_RST | TH_ACK;
1122                 }
1123         } else {
1124                 /*
1125                  * We are sending a keepalive. flags & TH_SYN determines
1126                  * the direction, forward if set, reverse if clear.
1127                  * NOTE: seq and ack are always assumed to be correct
1128                  * as set by the caller. This may be confusing...
1129                  */
1130                 if (flags & TH_SYN) {
1131                         /*
1132                          * we have to rewrite the correct addresses!
1133                          */
1134                         ip->ip_dst.s_addr = htonl(id->dst_ip);
1135                         ip->ip_src.s_addr = htonl(id->src_ip);
1136                         tcp->th_dport = htons(id->dst_port);
1137                         tcp->th_sport = htons(id->src_port);
1138                 }
1139                 tcp->th_seq = htonl(seq);
1140                 tcp->th_ack = htonl(ack);
1141                 tcp->th_flags = TH_ACK;
1142         }
1143         /*
1144          * set ip_len to the payload size so we can compute
1145          * the tcp checksum on the pseudoheader
1146          * XXX check this, could save a couple of words ?
1147          */
1148         ip->ip_len = htons(sizeof(struct tcphdr));
1149         tcp->th_sum = in_cksum(m, m->m_pkthdr.len);
1150         /*
1151          * now fill fields left out earlier
1152          */
1153         ip->ip_ttl = ip_defttl;
1154         ip->ip_len = m->m_pkthdr.len;
1155         bzero (&sro, sizeof (sro));
1156         ip_rtaddr(ip->ip_dst, &sro);
1157         m->m_pkthdr.fw_flags |= IPFW_MBUF_GENERATED;
1158         ip_output(m, NULL, &sro, 0, NULL, NULL);
1159         if (sro.ro_rt)
1160                 RTFREE(sro.ro_rt);
1161 }
1162
1163 /*
1164  * sends a reject message, consuming the mbuf passed as an argument.
1165  */
1166 static void
1167 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len)
1168 {
1169
1170         if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */
1171                 /* We need the IP header in host order for icmp_error(). */
1172                 if (args->eh != NULL) {
1173                         struct ip *ip = mtod(args->m, struct ip *);
1174                         ip->ip_len = ntohs(ip->ip_len);
1175                         ip->ip_off = ntohs(ip->ip_off);
1176                 }
1177                 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0);
1178         } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) {
1179                 struct tcphdr *const tcp =
1180                     L3HDR(struct tcphdr, mtod(args->m, struct ip *));
1181                 if ( (tcp->th_flags & TH_RST) == 0)
1182                         send_pkt(&(args->f_id), ntohl(tcp->th_seq),
1183                                 ntohl(tcp->th_ack),
1184                                 tcp->th_flags | TH_RST);
1185                 m_freem(args->m);
1186         } else
1187                 m_freem(args->m);
1188         args->m = NULL;
1189 }
1190
1191 /**
1192  *
1193  * Given an ip_fw *, lookup_next_rule will return a pointer
1194  * to the next rule, which can be either the jump
1195  * target (for skipto instructions) or the next one in the list (in
1196  * all other cases including a missing jump target).
1197  * The result is also written in the "next_rule" field of the rule.
1198  * Backward jumps are not allowed, so start looking from the next
1199  * rule...
1200  *
1201  * This never returns NULL -- in case we do not have an exact match,
1202  * the next rule is returned. When the ruleset is changed,
1203  * pointers are flushed so we are always correct.
1204  */
1205
1206 static struct ip_fw *
1207 lookup_next_rule(struct ip_fw *me)
1208 {
1209         struct ip_fw *rule = NULL;
1210         ipfw_insn *cmd;
1211
1212         /* look for action, in case it is a skipto */
1213         cmd = ACTION_PTR(me);
1214         if (cmd->opcode == O_LOG)
1215                 cmd += F_LEN(cmd);
1216         if ( cmd->opcode == O_SKIPTO )
1217                 for (rule = me->next; rule ; rule = rule->next)
1218                         if (rule->rulenum >= cmd->arg1)
1219                                 break;
1220         if (rule == NULL)                       /* failure or not a skipto */
1221                 rule = me->next;
1222         me->next_rule = rule;
1223         return rule;
1224 }
1225
1226 /*
1227  * The main check routine for the firewall.
1228  *
1229  * All arguments are in args so we can modify them and return them
1230  * back to the caller.
1231  *
1232  * Parameters:
1233  *
1234  *      args->m (in/out) The packet; we set to NULL when/if we nuke it.
1235  *              Starts with the IP header.
1236  *      args->eh (in)   Mac header if present, or NULL for layer3 packet.
1237  *      args->oif       Outgoing interface, or NULL if packet is incoming.
1238  *              The incoming interface is in the mbuf. (in)
1239  *
1240  *      args->rule      Pointer to the last matching rule (in/out)
1241  *      args->next_hop  Socket we are forwarding to (out).
1242  *      args->f_id      Addresses grabbed from the packet (out)
1243  *
1244  * Return value:
1245  *
1246  *      IP_FW_PORT_DENY_FLAG    the packet must be dropped.
1247  *      0       The packet is to be accepted and routed normally OR
1248  *              the packet was denied/rejected and has been dropped;
1249  *              in the latter case, *m is equal to NULL upon return.
1250  *      port    Divert the packet to port, with these caveats:
1251  *
1252  *              - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead
1253  *                of diverting it (ie, 'ipfw tee').
1254  *
1255  *              - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower
1256  *                16 bits as a dummynet pipe number instead of diverting
1257  */
1258
1259 static int
1260 ipfw_chk(struct ip_fw_args *args)
1261 {
1262         /*
1263          * Local variables hold state during the processing of a packet.
1264          *
1265          * IMPORTANT NOTE: to speed up the processing of rules, there
1266          * are some assumption on the values of the variables, which
1267          * are documented here. Should you change them, please check
1268          * the implementation of the various instructions to make sure
1269          * that they still work.
1270          *
1271          * args->eh     The MAC header. It is non-null for a layer2
1272          *      packet, it is NULL for a layer-3 packet.
1273          *
1274          * m | args->m  Pointer to the mbuf, as received from the caller.
1275          *      It may change if ipfw_chk() does an m_pullup, or if it
1276          *      consumes the packet because it calls send_reject().
1277          *      XXX This has to change, so that ipfw_chk() never modifies
1278          *      or consumes the buffer.
1279          * ip   is simply an alias of the value of m, and it is kept
1280          *      in sync with it (the packet is  supposed to start with
1281          *      the ip header).
1282          */
1283         struct mbuf *m = args->m;
1284         struct ip *ip = mtod(m, struct ip *);
1285
1286         /*
1287          * oif | args->oif      If NULL, ipfw_chk has been called on the
1288          *      inbound path (ether_input, ip_input).
1289          *      If non-NULL, ipfw_chk has been called on the outbound path
1290          *      (ether_output, ip_output).
1291          */
1292         struct ifnet *oif = args->oif;
1293
1294         struct ip_fw *f = NULL;         /* matching rule */
1295         int retval = 0;
1296         struct m_tag *mtag;
1297
1298         /*
1299          * hlen The length of the IPv4 header.
1300          *      hlen >0 means we have an IPv4 packet.
1301          */
1302         u_int hlen = 0;         /* hlen >0 means we have an IP pkt */
1303
1304         /*
1305          * offset       The offset of a fragment. offset != 0 means that
1306          *      we have a fragment at this offset of an IPv4 packet.
1307          *      offset == 0 means that (if this is an IPv4 packet)
1308          *      this is the first or only fragment.
1309          */
1310         u_short offset = 0;
1311
1312         /*
1313          * Local copies of addresses. They are only valid if we have
1314          * an IP packet.
1315          *
1316          * proto        The protocol. Set to 0 for non-ip packets,
1317          *      or to the protocol read from the packet otherwise.
1318          *      proto != 0 means that we have an IPv4 packet.
1319          *
1320          * src_port, dst_port   port numbers, in HOST format. Only
1321          *      valid for TCP and UDP packets.
1322          *
1323          * src_ip, dst_ip       ip addresses, in NETWORK format.
1324          *      Only valid for IPv4 packets.
1325          */
1326         uint8_t proto;
1327         uint16_t src_port = 0, dst_port = 0;    /* NOTE: host format    */
1328         struct in_addr src_ip, dst_ip;          /* NOTE: network format */
1329         uint16_t ip_len=0;
1330         int dyn_dir = MATCH_UNKNOWN;
1331         ipfw_dyn_rule *q = NULL;
1332
1333         if (m->m_pkthdr.fw_flags & IPFW_MBUF_GENERATED)
1334                 return 0;       /* accept */
1335         /*
1336          * dyn_dir = MATCH_UNKNOWN when rules unchecked,
1337          *      MATCH_NONE when checked and not matched (q = NULL),
1338          *      MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL)
1339          */
1340
1341         if (args->eh == NULL ||         /* layer 3 packet */
1342                 ( m->m_pkthdr.len >= sizeof(struct ip) &&
1343                     ntohs(args->eh->ether_type) == ETHERTYPE_IP))
1344                         hlen = ip->ip_hl << 2;
1345
1346         /*
1347          * Collect parameters into local variables for faster matching.
1348          */
1349         if (hlen == 0) {        /* do not grab addresses for non-ip pkts */
1350                 proto = args->f_id.proto = 0;   /* mark f_id invalid */
1351                 goto after_ip_checks;
1352         }
1353
1354         proto = args->f_id.proto = ip->ip_p;
1355         src_ip = ip->ip_src;
1356         dst_ip = ip->ip_dst;
1357         if (args->eh != NULL) { /* layer 2 packets are as on the wire */
1358                 offset = ntohs(ip->ip_off) & IP_OFFMASK;
1359                 ip_len = ntohs(ip->ip_len);
1360         } else {
1361                 offset = ip->ip_off & IP_OFFMASK;
1362                 ip_len = ip->ip_len;
1363         }
1364
1365 #define PULLUP_TO(len)                                          \
1366                 do {                                            \
1367                         if ((m)->m_len < (len)) {               \
1368                             args->m = m = m_pullup(m, (len));   \
1369                             if (m == 0)                         \
1370                                 goto pullup_failed;             \
1371                             ip = mtod(m, struct ip *);          \
1372                         }                                       \
1373                 } while (0)
1374
1375         if (offset == 0) {
1376                 switch (proto) {
1377                 case IPPROTO_TCP:
1378                     {
1379                         struct tcphdr *tcp;
1380
1381                         PULLUP_TO(hlen + sizeof(struct tcphdr));
1382                         tcp = L3HDR(struct tcphdr, ip);
1383                         dst_port = tcp->th_dport;
1384                         src_port = tcp->th_sport;
1385                         args->f_id.flags = tcp->th_flags;
1386                         }
1387                         break;
1388
1389                 case IPPROTO_UDP:
1390                     {
1391                         struct udphdr *udp;
1392
1393                         PULLUP_TO(hlen + sizeof(struct udphdr));
1394                         udp = L3HDR(struct udphdr, ip);
1395                         dst_port = udp->uh_dport;
1396                         src_port = udp->uh_sport;
1397                         }
1398                         break;
1399
1400                 case IPPROTO_ICMP:
1401                         PULLUP_TO(hlen + 4);    /* type, code and checksum. */
1402                         args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type;
1403                         break;
1404
1405                 default:
1406                         break;
1407                 }
1408 #undef PULLUP_TO
1409         }
1410
1411         args->f_id.src_ip = ntohl(src_ip.s_addr);
1412         args->f_id.dst_ip = ntohl(dst_ip.s_addr);
1413         args->f_id.src_port = src_port = ntohs(src_port);
1414         args->f_id.dst_port = dst_port = ntohs(dst_port);
1415
1416 after_ip_checks:
1417         if (args->rule) {
1418                 /*
1419                  * Packet has already been tagged. Look for the next rule
1420                  * to restart processing.
1421                  *
1422                  * If fw_one_pass != 0 then just accept it.
1423                  * XXX should not happen here, but optimized out in
1424                  * the caller.
1425                  */
1426                 if (fw_one_pass)
1427                         return 0;
1428
1429                 /* This rule was deleted */
1430                 if (args->rule->rule_flags & IPFW_RULE_F_INVALID)
1431                         return IP_FW_PORT_DENY_FLAG;
1432
1433                 f = args->rule->next_rule;
1434                 if (f == NULL)
1435                         f = lookup_next_rule(args->rule);
1436         } else {
1437                 /*
1438                  * Find the starting rule. It can be either the first
1439                  * one, or the one after divert_rule if asked so.
1440                  */
1441                 int skipto;
1442
1443                 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
1444                 if (mtag != NULL)
1445                         skipto = *(uint16_t *)m_tag_data(mtag);
1446                 else
1447                         skipto = 0;
1448
1449                 f = layer3_chain;
1450                 if (args->eh == NULL && skipto != 0) {
1451                         if (skipto >= IPFW_DEFAULT_RULE)
1452                                 return(IP_FW_PORT_DENY_FLAG); /* invalid */
1453                         while (f && f->rulenum <= skipto)
1454                                 f = f->next;
1455                         if (f == NULL)  /* drop packet */
1456                                 return(IP_FW_PORT_DENY_FLAG);
1457                 }
1458         }
1459         if ((mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL)) != NULL)
1460                 m_tag_delete(m, mtag);
1461
1462         /*
1463          * Now scan the rules, and parse microinstructions for each rule.
1464          */
1465         for (; f; f = f->next) {
1466                 int l, cmdlen;
1467                 ipfw_insn *cmd;
1468                 int skip_or; /* skip rest of OR block */
1469
1470 again:
1471                 if (set_disable & (1 << f->set) )
1472                         continue;
1473
1474                 skip_or = 0;
1475                 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ;
1476                     l -= cmdlen, cmd += cmdlen) {
1477                         int match;
1478
1479                         /*
1480                          * check_body is a jump target used when we find a
1481                          * CHECK_STATE, and need to jump to the body of
1482                          * the target rule.
1483                          */
1484
1485 check_body:
1486                         cmdlen = F_LEN(cmd);
1487                         /*
1488                          * An OR block (insn_1 || .. || insn_n) has the
1489                          * F_OR bit set in all but the last instruction.
1490                          * The first match will set "skip_or", and cause
1491                          * the following instructions to be skipped until
1492                          * past the one with the F_OR bit clear.
1493                          */
1494                         if (skip_or) {          /* skip this instruction */
1495                                 if ((cmd->len & F_OR) == 0)
1496                                         skip_or = 0;    /* next one is good */
1497                                 continue;
1498                         }
1499                         match = 0; /* set to 1 if we succeed */
1500
1501                         switch (cmd->opcode) {
1502                         /*
1503                          * The first set of opcodes compares the packet's
1504                          * fields with some pattern, setting 'match' if a
1505                          * match is found. At the end of the loop there is
1506                          * logic to deal with F_NOT and F_OR flags associated
1507                          * with the opcode.
1508                          */
1509                         case O_NOP:
1510                                 match = 1;
1511                                 break;
1512
1513                         case O_FORWARD_MAC:
1514                                 kprintf("ipfw: opcode %d unimplemented\n",
1515                                     cmd->opcode);
1516                                 break;
1517
1518                         case O_GID:
1519                         case O_UID:
1520                                 /*
1521                                  * We only check offset == 0 && proto != 0,
1522                                  * as this ensures that we have an IPv4
1523                                  * packet with the ports info.
1524                                  */
1525                                 if (offset!=0)
1526                                         break;
1527                             {
1528                                 struct inpcbinfo *pi;
1529                                 int wildcard;
1530                                 struct inpcb *pcb;
1531
1532                                 if (proto == IPPROTO_TCP) {
1533                                         wildcard = 0;
1534                                         pi = &tcbinfo[mycpu->gd_cpuid];
1535                                 } else if (proto == IPPROTO_UDP) {
1536                                         wildcard = 1;
1537                                         pi = &udbinfo;
1538                                 } else
1539                                         break;
1540
1541                                 pcb =  (oif) ?
1542                                         in_pcblookup_hash(pi,
1543                                             dst_ip, htons(dst_port),
1544                                             src_ip, htons(src_port),
1545                                             wildcard, oif) :
1546                                         in_pcblookup_hash(pi,
1547                                             src_ip, htons(src_port),
1548                                             dst_ip, htons(dst_port),
1549                                             wildcard, NULL);
1550
1551                                 if (pcb == NULL || pcb->inp_socket == NULL)
1552                                         break;
1553 #if defined(__DragonFly__) || (defined(__FreeBSD__) && __FreeBSD_version < 500034)
1554 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b))
1555 #endif
1556                                 if (cmd->opcode == O_UID) {
1557                                         match =
1558                                           !socheckuid(pcb->inp_socket,
1559                                            (uid_t)((ipfw_insn_u32 *)cmd)->d[0]);
1560                                 } else  {
1561                                         match = groupmember(
1562                                             (uid_t)((ipfw_insn_u32 *)cmd)->d[0],
1563                                             pcb->inp_socket->so_cred);
1564                                 }
1565                             }
1566                                 break;
1567
1568                         case O_RECV:
1569                                 match = iface_match(m->m_pkthdr.rcvif,
1570                                     (ipfw_insn_if *)cmd);
1571                                 break;
1572
1573                         case O_XMIT:
1574                                 match = iface_match(oif, (ipfw_insn_if *)cmd);
1575                                 break;
1576
1577                         case O_VIA:
1578                                 match = iface_match(oif ? oif :
1579                                     m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd);
1580                                 break;
1581
1582                         case O_MACADDR2:
1583                                 if (args->eh != NULL) { /* have MAC header */
1584                                         uint32_t *want = (uint32_t *)
1585                                                 ((ipfw_insn_mac *)cmd)->addr;
1586                                         uint32_t *mask = (uint32_t *)
1587                                                 ((ipfw_insn_mac *)cmd)->mask;
1588                                         uint32_t *hdr = (uint32_t *)args->eh;
1589
1590                                         match =
1591                                             ( want[0] == (hdr[0] & mask[0]) &&
1592                                               want[1] == (hdr[1] & mask[1]) &&
1593                                               want[2] == (hdr[2] & mask[2]) );
1594                                 }
1595                                 break;
1596
1597                         case O_MAC_TYPE:
1598                                 if (args->eh != NULL) {
1599                                         uint16_t t =
1600                                             ntohs(args->eh->ether_type);
1601                                         uint16_t *p =
1602                                             ((ipfw_insn_u16 *)cmd)->ports;
1603                                         int i;
1604
1605                                         /* Special vlan handling */
1606                                         if (m->m_flags & M_VLANTAG)
1607                                                 t = ETHERTYPE_VLAN;
1608
1609                                         for (i = cmdlen - 1; !match && i>0;
1610                                             i--, p += 2)
1611                                                 match = (t>=p[0] && t<=p[1]);
1612                                 }
1613                                 break;
1614
1615                         case O_FRAG:
1616                                 match = (hlen > 0 && offset != 0);
1617                                 break;
1618
1619                         case O_IN:      /* "out" is "not in" */
1620                                 match = (oif == NULL);
1621                                 break;
1622
1623                         case O_LAYER2:
1624                                 match = (args->eh != NULL);
1625                                 break;
1626
1627                         case O_PROTO:
1628                                 /*
1629                                  * We do not allow an arg of 0 so the
1630                                  * check of "proto" only suffices.
1631                                  */
1632                                 match = (proto == cmd->arg1);
1633                                 break;
1634
1635                         case O_IP_SRC:
1636                                 match = (hlen > 0 &&
1637                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1638                                     src_ip.s_addr);
1639                                 break;
1640
1641                         case O_IP_SRC_MASK:
1642                                 match = (hlen > 0 &&
1643                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1644                                      (src_ip.s_addr &
1645                                      ((ipfw_insn_ip *)cmd)->mask.s_addr));
1646                                 break;
1647
1648                         case O_IP_SRC_ME:
1649                                 if (hlen > 0) {
1650                                         struct ifnet *tif;
1651
1652                                         tif = INADDR_TO_IFP(&src_ip);
1653                                         match = (tif != NULL);
1654                                 }
1655                                 break;
1656
1657                         case O_IP_DST_SET:
1658                         case O_IP_SRC_SET:
1659                                 if (hlen > 0) {
1660                                         uint32_t *d = (uint32_t *)(cmd+1);
1661                                         uint32_t addr =
1662                                             cmd->opcode == O_IP_DST_SET ?
1663                                                 args->f_id.dst_ip :
1664                                                 args->f_id.src_ip;
1665
1666                                             if (addr < d[0])
1667                                                     break;
1668                                             addr -= d[0]; /* subtract base */
1669                                             match = (addr < cmd->arg1) &&
1670                                                 ( d[ 1 + (addr>>5)] &
1671                                                   (1<<(addr & 0x1f)) );
1672                                 }
1673                                 break;
1674
1675                         case O_IP_DST:
1676                                 match = (hlen > 0 &&
1677                                     ((ipfw_insn_ip *)cmd)->addr.s_addr ==
1678                                     dst_ip.s_addr);
1679                                 break;
1680
1681                         case O_IP_DST_MASK:
1682                                 match = (hlen > 0) &&
1683                                     (((ipfw_insn_ip *)cmd)->addr.s_addr ==
1684                                      (dst_ip.s_addr &
1685                                      ((ipfw_insn_ip *)cmd)->mask.s_addr));
1686                                 break;
1687
1688                         case O_IP_DST_ME:
1689                                 if (hlen > 0) {
1690                                         struct ifnet *tif;
1691
1692                                         tif = INADDR_TO_IFP(&dst_ip);
1693                                         match = (tif != NULL);
1694                                 }
1695                                 break;
1696
1697                         case O_IP_SRCPORT:
1698                         case O_IP_DSTPORT:
1699                                 /*
1700                                  * offset == 0 && proto != 0 is enough
1701                                  * to guarantee that we have an IPv4
1702                                  * packet with port info.
1703                                  */
1704                                 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP)
1705                                     && offset == 0) {
1706                                         uint16_t x =
1707                                             (cmd->opcode == O_IP_SRCPORT) ?
1708                                                 src_port : dst_port ;
1709                                         uint16_t *p =
1710                                             ((ipfw_insn_u16 *)cmd)->ports;
1711                                         int i;
1712
1713                                         for (i = cmdlen - 1; !match && i>0;
1714                                             i--, p += 2)
1715                                                 match = (x>=p[0] && x<=p[1]);
1716                                 }
1717                                 break;
1718
1719                         case O_ICMPTYPE:
1720                                 match = (offset == 0 && proto==IPPROTO_ICMP &&
1721                                     icmptype_match(ip, (ipfw_insn_u32 *)cmd) );
1722                                 break;
1723
1724                         case O_IPOPT:
1725                                 match = (hlen > 0 && ipopts_match(ip, cmd) );
1726                                 break;
1727
1728                         case O_IPVER:
1729                                 match = (hlen > 0 && cmd->arg1 == ip->ip_v);
1730                                 break;
1731
1732                         case O_IPTTL:
1733                                 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl);
1734                                 break;
1735
1736                         case O_IPID:
1737                                 match = (hlen > 0 &&
1738                                     cmd->arg1 == ntohs(ip->ip_id));
1739                                 break;
1740
1741                         case O_IPLEN:
1742                                 match = (hlen > 0 && cmd->arg1 == ip_len);
1743                                 break;
1744
1745                         case O_IPPRECEDENCE:
1746                                 match = (hlen > 0 &&
1747                                     (cmd->arg1 == (ip->ip_tos & 0xe0)) );
1748                                 break;
1749
1750                         case O_IPTOS:
1751                                 match = (hlen > 0 &&
1752                                     flags_match(cmd, ip->ip_tos));
1753                                 break;
1754
1755                         case O_TCPFLAGS:
1756                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1757                                     flags_match(cmd,
1758                                         L3HDR(struct tcphdr,ip)->th_flags));
1759                                 break;
1760
1761                         case O_TCPOPTS:
1762                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1763                                     tcpopts_match(ip, cmd));
1764                                 break;
1765
1766                         case O_TCPSEQ:
1767                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1768                                     ((ipfw_insn_u32 *)cmd)->d[0] ==
1769                                         L3HDR(struct tcphdr,ip)->th_seq);
1770                                 break;
1771
1772                         case O_TCPACK:
1773                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1774                                     ((ipfw_insn_u32 *)cmd)->d[0] ==
1775                                         L3HDR(struct tcphdr,ip)->th_ack);
1776                                 break;
1777
1778                         case O_TCPWIN:
1779                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1780                                     cmd->arg1 ==
1781                                         L3HDR(struct tcphdr,ip)->th_win);
1782                                 break;
1783
1784                         case O_ESTAB:
1785                                 /* reject packets which have SYN only */
1786                                 /* XXX should i also check for TH_ACK ? */
1787                                 match = (proto == IPPROTO_TCP && offset == 0 &&
1788                                     (L3HDR(struct tcphdr,ip)->th_flags &
1789                                      (TH_RST | TH_ACK | TH_SYN)) != TH_SYN);
1790                                 break;
1791
1792                         case O_LOG:
1793                                 if (fw_verbose)
1794                                         ipfw_log(f, hlen, args->eh, m, oif);
1795                                 match = 1;
1796                                 break;
1797
1798                         case O_PROB:
1799                                 match = (krandom() <
1800                                         ((ipfw_insn_u32 *)cmd)->d[0]);
1801                                 break;
1802
1803                         /*
1804                          * The second set of opcodes represents 'actions',
1805                          * i.e. the terminal part of a rule once the packet
1806                          * matches all previous patterns.
1807                          * Typically there is only one action for each rule,
1808                          * and the opcode is stored at the end of the rule
1809                          * (but there are exceptions -- see below).
1810                          *
1811                          * In general, here we set retval and terminate the
1812                          * outer loop (would be a 'break 3' in some language,
1813                          * but we need to do a 'goto done').
1814                          *
1815                          * Exceptions:
1816                          * O_COUNT and O_SKIPTO actions:
1817                          *   instead of terminating, we jump to the next rule
1818                          *   ('goto next_rule', equivalent to a 'break 2'),
1819                          *   or to the SKIPTO target ('goto again' after
1820                          *   having set f, cmd and l), respectively.
1821                          *
1822                          * O_LIMIT and O_KEEP_STATE: these opcodes are
1823                          *   not real 'actions', and are stored right
1824                          *   before the 'action' part of the rule.
1825                          *   These opcodes try to install an entry in the
1826                          *   state tables; if successful, we continue with
1827                          *   the next opcode (match=1; break;), otherwise
1828                          *   the packet *   must be dropped
1829                          *   ('goto done' after setting retval);
1830                          *
1831                          * O_PROBE_STATE and O_CHECK_STATE: these opcodes
1832                          *   cause a lookup of the state table, and a jump
1833                          *   to the 'action' part of the parent rule
1834                          *   ('goto check_body') if an entry is found, or
1835                          *   (CHECK_STATE only) a jump to the next rule if
1836                          *   the entry is not found ('goto next_rule').
1837                          *   The result of the lookup is cached to make
1838                          *   further instances of these opcodes are
1839                          *   effectively NOPs.
1840                          */
1841                         case O_LIMIT:
1842                         case O_KEEP_STATE:
1843                                 if (install_state(f,
1844                                     (ipfw_insn_limit *)cmd, args)) {
1845                                         retval = IP_FW_PORT_DENY_FLAG;
1846                                         goto done; /* error/limit violation */
1847                                 }
1848                                 match = 1;
1849                                 break;
1850
1851                         case O_PROBE_STATE:
1852                         case O_CHECK_STATE:
1853                                 /*
1854                                  * dynamic rules are checked at the first
1855                                  * keep-state or check-state occurrence,
1856                                  * with the result being stored in dyn_dir.
1857                                  * The compiler introduces a PROBE_STATE
1858                                  * instruction for us when we have a
1859                                  * KEEP_STATE (because PROBE_STATE needs
1860                                  * to be run first).
1861                                  */
1862                                 if (dyn_dir == MATCH_UNKNOWN &&
1863                                     (q = lookup_dyn_rule(&args->f_id,
1864                                      &dyn_dir, proto == IPPROTO_TCP ?
1865                                         L3HDR(struct tcphdr, ip) : NULL))
1866                                         != NULL) {
1867                                         /*
1868                                          * Found dynamic entry, update stats
1869                                          * and jump to the 'action' part of
1870                                          * the parent rule.
1871                                          */
1872                                         q->pcnt++;
1873                                         q->bcnt += ip_len;
1874                                         f = q->rule;
1875                                         cmd = ACTION_PTR(f);
1876                                         l = f->cmd_len - f->act_ofs;
1877                                         goto check_body;
1878                                 }
1879                                 /*
1880                                  * Dynamic entry not found. If CHECK_STATE,
1881                                  * skip to next rule, if PROBE_STATE just
1882                                  * ignore and continue with next opcode.
1883                                  */
1884                                 if (cmd->opcode == O_CHECK_STATE)
1885                                         goto next_rule;
1886                                 match = 1;
1887                                 break;
1888
1889                         case O_ACCEPT:
1890                                 retval = 0;     /* accept */
1891                                 goto done;
1892
1893                         case O_PIPE:
1894                         case O_QUEUE:
1895                                 args->rule = f; /* report matching rule */
1896                                 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG;
1897                                 goto done;
1898
1899                         case O_DIVERT:
1900                         case O_TEE:
1901                                 if (args->eh) /* not on layer 2 */
1902                                         break;
1903
1904                                 mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT,
1905                                                  sizeof(uint16_t), MB_DONTWAIT);
1906                                 if (mtag == NULL) {
1907                                         retval = IP_FW_PORT_DENY_FLAG;
1908                                         goto done;
1909                                 }
1910                                 *(uint16_t *)m_tag_data(mtag) = f->rulenum;
1911                                 m_tag_prepend(m, mtag);
1912                                 retval = (cmd->opcode == O_DIVERT) ?
1913                                     cmd->arg1 :
1914                                     cmd->arg1 | IP_FW_PORT_TEE_FLAG;
1915                                 goto done;
1916
1917                         case O_COUNT:
1918                         case O_SKIPTO:
1919                                 f->pcnt++;      /* update stats */
1920                                 f->bcnt += ip_len;
1921                                 f->timestamp = time_second;
1922                                 if (cmd->opcode == O_COUNT)
1923                                         goto next_rule;
1924                                 /* handle skipto */
1925                                 if (f->next_rule == NULL)
1926                                         lookup_next_rule(f);
1927                                 f = f->next_rule;
1928                                 goto again;
1929
1930                         case O_REJECT:
1931                                 /*
1932                                  * Drop the packet and send a reject notice
1933                                  * if the packet is not ICMP (or is an ICMP
1934                                  * query), and it is not multicast/broadcast.
1935                                  */
1936                                 if (hlen > 0 &&
1937                                     (proto != IPPROTO_ICMP ||
1938                                      is_icmp_query(ip)) &&
1939                                     !(m->m_flags & (M_BCAST|M_MCAST)) &&
1940                                     !IN_MULTICAST(ntohl(dst_ip.s_addr))) {
1941                                         send_reject(args, cmd->arg1,
1942                                             offset,ip_len);
1943                                         m = args->m;
1944                                 }
1945                                 /* FALLTHROUGH */
1946                         case O_DENY:
1947                                 retval = IP_FW_PORT_DENY_FLAG;
1948                                 goto done;
1949
1950                         case O_FORWARD_IP:
1951                                 if (args->eh)   /* not valid on layer2 pkts */
1952                                         break;
1953                                 if (!q || dyn_dir == MATCH_FORWARD)
1954                                         args->next_hop =
1955                                             &((ipfw_insn_sa *)cmd)->sa;
1956                                 retval = 0;
1957                                 goto done;
1958
1959                         default:
1960                                 panic("-- unknown opcode %d\n", cmd->opcode);
1961                         } /* end of switch() on opcodes */
1962
1963                         if (cmd->len & F_NOT)
1964                                 match = !match;
1965
1966                         if (match) {
1967                                 if (cmd->len & F_OR)
1968                                         skip_or = 1;
1969                         } else {
1970                                 if (!(cmd->len & F_OR)) /* not an OR block, */
1971                                         break;          /* try next rule    */
1972                         }
1973
1974                 }       /* end of inner for, scan opcodes */
1975
1976 next_rule:;             /* try next rule                */
1977
1978         }               /* end of outer for, scan rules */
1979         kprintf("+++ ipfw: ouch!, skip past end of rules, denying packet\n");
1980         return(IP_FW_PORT_DENY_FLAG);
1981
1982 done:
1983         /* Update statistics */
1984         f->pcnt++;
1985         f->bcnt += ip_len;
1986         f->timestamp = time_second;
1987         return retval;
1988
1989 pullup_failed:
1990         if (fw_verbose)
1991                 kprintf("pullup failed\n");
1992         return(IP_FW_PORT_DENY_FLAG);
1993 }
1994
1995 static void
1996 ipfw_dummynet_io(struct mbuf *m, int pipe_nr, int dir, struct ip_fw_args *fwa)
1997 {
1998         struct m_tag *mtag;
1999         struct dn_pkt *pkt;
2000         ipfw_insn *cmd;
2001         const struct ipfw_flow_id *id;
2002         struct dn_flow_id *fid;
2003
2004         M_ASSERTPKTHDR(m);
2005
2006         mtag = m_tag_get(PACKET_TAG_DUMMYNET, sizeof(*pkt), MB_DONTWAIT);
2007         if (mtag == NULL) {
2008                 m_freem(m);
2009                 return;
2010         }
2011         m_tag_prepend(m, mtag);
2012
2013         pkt = m_tag_data(mtag);
2014         bzero(pkt, sizeof(*pkt));
2015
2016         cmd = fwa->rule->cmd + fwa->rule->act_ofs;
2017         if (cmd->opcode == O_LOG)
2018                 cmd += F_LEN(cmd);
2019         KASSERT(cmd->opcode == O_PIPE || cmd->opcode == O_QUEUE,
2020                 ("Rule is not PIPE or QUEUE, opcode %d\n", cmd->opcode));
2021
2022         pkt->dn_m = m;
2023         pkt->dn_flags = (dir & DN_FLAGS_DIR_MASK);
2024         pkt->ifp = fwa->oif;
2025         pkt->cpuid = mycpu->gd_cpuid;
2026         pkt->pipe_nr = pipe_nr;
2027
2028         id = &fwa->f_id;
2029         fid = &pkt->id;
2030         fid->fid_dst_ip = id->dst_ip;
2031         fid->fid_src_ip = id->src_ip;
2032         fid->fid_dst_port = id->dst_port;
2033         fid->fid_src_port = id->src_port;
2034         fid->fid_proto = id->proto;
2035         fid->fid_flags = id->flags;
2036
2037         ipfw_ref_rule(fwa->rule);
2038         pkt->dn_priv = fwa->rule;
2039         pkt->dn_unref_priv = ipfw_unref_rule;
2040
2041         if (cmd->opcode == O_PIPE)
2042                 pkt->dn_flags |= DN_FLAGS_IS_PIPE;
2043
2044         if (dir == DN_TO_IP_OUT) {
2045                 /*
2046                  * We need to copy *ro because for ICMP pkts (and maybe
2047                  * others) the caller passed a pointer into the stack;
2048                  * dst might also be a pointer into *ro so it needs to
2049                  * be updated.
2050                  */
2051                 pkt->ro = *(fwa->ro);
2052                 if (fwa->ro->ro_rt)
2053                         fwa->ro->ro_rt->rt_refcnt++;
2054                 if (fwa->dst == (struct sockaddr_in *)&fwa->ro->ro_dst) {
2055                         /* 'dst' points into 'ro' */
2056                         fwa->dst = (struct sockaddr_in *)&(pkt->ro.ro_dst);
2057                 }
2058                 pkt->dn_dst = fwa->dst;
2059                 pkt->flags = fwa->flags;
2060         }
2061
2062         m->m_pkthdr.fw_flags |= DUMMYNET_MBUF_TAGGED;
2063         ip_dn_queue(m);
2064 }
2065
2066 /*
2067  * When a rule is added/deleted, clear the next_rule pointers in all rules.
2068  * These will be reconstructed on the fly as packets are matched.
2069  * Must be called at splimp().
2070  */
2071 static void
2072 flush_rule_ptrs(void)
2073 {
2074         struct ip_fw *rule;
2075
2076         for (rule = layer3_chain; rule; rule = rule->next)
2077                 rule->next_rule = NULL;
2078 }
2079
2080 static __inline void
2081 ipfw_inc_static_count(struct ip_fw *rule)
2082 {
2083         static_count++;
2084         static_ioc_len += IOC_RULESIZE(rule);
2085 }
2086
2087 static __inline void
2088 ipfw_dec_static_count(struct ip_fw *rule)
2089 {
2090         int l = IOC_RULESIZE(rule);
2091
2092         KASSERT(static_count > 0, ("invalid static count %u\n", static_count));
2093         static_count--;
2094
2095         KASSERT(static_ioc_len >= l,
2096                 ("invalid static len %u\n", static_ioc_len));
2097         static_ioc_len -= l;
2098 }
2099
2100 static struct ip_fw *
2101 ipfw_create_rule(const struct ipfw_ioc_rule *ioc_rule)
2102 {
2103         struct ip_fw *rule;
2104
2105         rule = kmalloc(RULESIZE(ioc_rule), M_IPFW, M_WAITOK | M_ZERO);
2106
2107         rule->act_ofs = ioc_rule->act_ofs;
2108         rule->cmd_len = ioc_rule->cmd_len;
2109         rule->rulenum = ioc_rule->rulenum;
2110         rule->set = ioc_rule->set;
2111         rule->usr_flags = ioc_rule->usr_flags;
2112
2113         bcopy(ioc_rule->cmd, rule->cmd, rule->cmd_len * 4 /* XXX */);
2114
2115         rule->refcnt = 1;
2116
2117         return rule;
2118 }
2119
2120 /*
2121  * Add a new rule to the list. Copy the rule into a malloc'ed area, then
2122  * possibly create a rule number and add the rule to the list.
2123  * Update the rule_number in the input struct so the caller knows it as well.
2124  */
2125 static int
2126 ipfw_add_rule(struct ip_fw **head, struct ipfw_ioc_rule *ioc_rule)
2127 {
2128         struct ip_fw *rule, *f, *prev;
2129
2130         KKASSERT(*head != NULL);
2131
2132         rule = ipfw_create_rule(ioc_rule);
2133
2134         crit_enter();
2135
2136         /*
2137          * If rulenum is 0, find highest numbered rule before the
2138          * default rule, and add autoinc_step
2139          */
2140         if (autoinc_step < 1)
2141                 autoinc_step = 1;
2142         else if (autoinc_step > 1000)
2143                 autoinc_step = 1000;
2144         if (rule->rulenum == 0) {
2145                 /*
2146                  * locate the highest numbered rule before default
2147                  */
2148                 for (f = *head; f; f = f->next) {
2149                         if (f->rulenum == IPFW_DEFAULT_RULE)
2150                                 break;
2151                         rule->rulenum = f->rulenum;
2152                 }
2153                 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step)
2154                         rule->rulenum += autoinc_step;
2155                 ioc_rule->rulenum = rule->rulenum;
2156         }
2157
2158         /*
2159          * Now insert the new rule in the right place in the sorted list.
2160          */
2161         for (prev = NULL, f = *head; f; prev = f, f = f->next) {
2162                 if (f->rulenum > rule->rulenum) { /* found the location */
2163                         if (prev) {
2164                                 rule->next = f;
2165                                 prev->next = rule;
2166                         } else { /* head insert */
2167                                 rule->next = *head;
2168                                 *head = rule;
2169                         }
2170                         break;
2171                 }
2172         }
2173
2174         flush_rule_ptrs();
2175         ipfw_inc_static_count(rule);
2176
2177         crit_exit();
2178
2179         DEB(kprintf("++ installed rule %d, static count now %d\n",
2180                 rule->rulenum, static_count);)
2181         return (0);
2182 }
2183
2184 /**
2185  * Free storage associated with a static rule (including derived
2186  * dynamic rules).
2187  * The caller is in charge of clearing rule pointers to avoid
2188  * dangling pointers.
2189  * @return a pointer to the next entry.
2190  * Arguments are not checked, so they better be correct.
2191  * Must be called at splimp().
2192  */
2193 static struct ip_fw *
2194 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule)
2195 {
2196         struct ip_fw *n;
2197
2198         n = rule->next;
2199         remove_dyn_rule(rule, NULL /* force removal */);
2200         if (prev == NULL)
2201                 *head = n;
2202         else
2203                 prev->next = n;
2204         ipfw_dec_static_count(rule);
2205
2206         /* Mark the rule as invalid */
2207         rule->rule_flags |= IPFW_RULE_F_INVALID;
2208         rule->next_rule = NULL;
2209
2210         /* Try to free this rule */
2211         ipfw_free_rule(rule);
2212
2213         return n;
2214 }
2215
2216 /*
2217  * Deletes all rules from a chain (including the default rule
2218  * if the second argument is set).
2219  * Must be called at splimp().
2220  */
2221 static void
2222 free_chain(struct ip_fw **chain, int kill_default)
2223 {
2224         struct ip_fw *rule;
2225
2226         flush_rule_ptrs(); /* more efficient to do outside the loop */
2227
2228         while ( (rule = *chain) != NULL &&
2229             (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) )
2230                 delete_rule(chain, NULL, rule);
2231
2232         KASSERT(dyn_count == 0, ("%u dyn rule remains\n", dyn_count));
2233
2234         if (kill_default) {
2235                 ip_fw_default_rule = NULL;      /* Reset default rule */
2236
2237                 if (ipfw_dyn_v != NULL) {
2238                         /*
2239                          * Free dynamic rules(state) hash table
2240                          */
2241                         kfree(ipfw_dyn_v, M_IPFW);
2242                         ipfw_dyn_v = NULL;
2243                 }
2244
2245                 KASSERT(static_count == 0,
2246                         ("%u static rules remains\n", static_count));
2247                 KASSERT(static_ioc_len == 0,
2248                         ("%u bytes of static rules remains\n", static_ioc_len));
2249         } else {
2250                 KASSERT(static_count == 1,
2251                         ("%u static rules remains\n", static_count));
2252                 KASSERT(static_ioc_len == IOC_RULESIZE(ip_fw_default_rule),
2253                         ("%u bytes of static rules remains, should be %u\n",
2254                          static_ioc_len, IOC_RULESIZE(ip_fw_default_rule)));
2255         }
2256 }
2257
2258 /**
2259  * Remove all rules with given number, and also do set manipulation.
2260  *
2261  * The argument is an uint32_t. The low 16 bit are the rule or set number,
2262  * the next 8 bits are the new set, the top 8 bits are the command:
2263  *
2264  *      0       delete rules with given number
2265  *      1       delete rules with given set number
2266  *      2       move rules with given number to new set
2267  *      3       move rules with given set number to new set
2268  *      4       swap sets with given numbers
2269  */
2270 static int
2271 del_entry(struct ip_fw **chain, uint32_t arg)
2272 {
2273         struct ip_fw *prev, *rule;
2274         uint16_t rulenum;
2275         uint8_t cmd, new_set;
2276
2277         rulenum = arg & 0xffff;
2278         cmd = (arg >> 24) & 0xff;
2279         new_set = (arg >> 16) & 0xff;
2280
2281         if (cmd > 4)
2282                 return EINVAL;
2283         if (new_set > 30)
2284                 return EINVAL;
2285         if (cmd == 0 || cmd == 2) {
2286                 if (rulenum == IPFW_DEFAULT_RULE)
2287                         return EINVAL;
2288         } else {
2289                 if (rulenum > 30)
2290                         return EINVAL;
2291         }
2292
2293         switch (cmd) {
2294         case 0: /* delete rules with given number */
2295                 /*
2296                  * locate first rule to delete
2297                  */
2298                 for (prev = NULL, rule = *chain;
2299                     rule && rule->rulenum < rulenum;
2300                      prev = rule, rule = rule->next)
2301                         ;
2302                 if (rule->rulenum != rulenum)
2303                         return EINVAL;
2304
2305                 crit_enter(); /* no access to rules while removing */
2306                 /*
2307                  * flush pointers outside the loop, then delete all matching
2308                  * rules. prev remains the same throughout the cycle.
2309                  */
2310                 flush_rule_ptrs();
2311                 while (rule && rule->rulenum == rulenum)
2312                         rule = delete_rule(chain, prev, rule);
2313                 crit_exit();
2314                 break;
2315
2316         case 1: /* delete all rules with given set number */
2317                 crit_enter();
2318                 flush_rule_ptrs();
2319                 for (prev = NULL, rule = *chain; rule ; )
2320                         if (rule->set == rulenum)
2321                                 rule = delete_rule(chain, prev, rule);
2322                         else {
2323                                 prev = rule;
2324                                 rule = rule->next;
2325                         }
2326                 crit_exit();
2327                 break;
2328
2329         case 2: /* move rules with given number to new set */
2330                 crit_enter();
2331                 for (rule = *chain; rule ; rule = rule->next)
2332                         if (rule->rulenum == rulenum)
2333                                 rule->set = new_set;
2334                 crit_exit();
2335                 break;
2336
2337         case 3: /* move rules with given set number to new set */
2338                 crit_enter();
2339                 for (rule = *chain; rule ; rule = rule->next)
2340                         if (rule->set == rulenum)
2341                                 rule->set = new_set;
2342                 crit_exit();
2343                 break;
2344
2345         case 4: /* swap two sets */
2346                 crit_enter();
2347                 for (rule = *chain; rule ; rule = rule->next)
2348                         if (rule->set == rulenum)
2349                                 rule->set = new_set;
2350                         else if (rule->set == new_set)
2351                                 rule->set = rulenum;
2352                 crit_exit();
2353                 break;
2354         }
2355         return 0;
2356 }
2357
2358 /*
2359  * Clear counters for a specific rule.
2360  */
2361 static void
2362 clear_counters(struct ip_fw *rule, int log_only)
2363 {
2364         ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule);
2365
2366         if (log_only == 0) {
2367                 rule->bcnt = rule->pcnt = 0;
2368                 rule->timestamp = 0;
2369         }
2370         if (l->o.opcode == O_LOG)
2371                 l->log_left = l->max_log;
2372 }
2373
2374 /**
2375  * Reset some or all counters on firewall rules.
2376  * @arg frwl is null to clear all entries, or contains a specific
2377  * rule number.
2378  * @arg log_only is 1 if we only want to reset logs, zero otherwise.
2379  */
2380 static int
2381 zero_entry(int rulenum, int log_only)
2382 {
2383         struct ip_fw *rule;
2384         char *msg;
2385
2386         if (rulenum == 0) {
2387                 crit_enter();
2388                 norule_counter = 0;
2389                 for (rule = layer3_chain; rule; rule = rule->next)
2390                         clear_counters(rule, log_only);
2391                 crit_exit();
2392                 msg = log_only ? "ipfw: All logging counts reset.\n" :
2393                                 "ipfw: Accounting cleared.\n";
2394         } else {
2395                 int cleared = 0;
2396                 /*
2397                  * We can have multiple rules with the same number, so we
2398                  * need to clear them all.
2399                  */
2400                 for (rule = layer3_chain; rule; rule = rule->next)
2401                         if (rule->rulenum == rulenum) {
2402                                 crit_enter();
2403                                 while (rule && rule->rulenum == rulenum) {
2404                                         clear_counters(rule, log_only);
2405                                         rule = rule->next;
2406                                 }
2407                                 crit_exit();
2408                                 cleared = 1;
2409                                 break;
2410                         }
2411                 if (!cleared)   /* we did not find any matching rules */
2412                         return (EINVAL);
2413                 msg = log_only ? "ipfw: Entry %d logging count reset.\n" :
2414                                 "ipfw: Entry %d cleared.\n";
2415         }
2416         if (fw_verbose)
2417                 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum);
2418         return (0);
2419 }
2420
2421 /*
2422  * Check validity of the structure before insert.
2423  * Fortunately rules are simple, so this mostly need to check rule sizes.
2424  */
2425 static int
2426 ipfw_ctl_check_rule(struct ipfw_ioc_rule *rule, int size)
2427 {
2428         int l, cmdlen = 0;
2429         int have_action = 0;
2430         ipfw_insn *cmd;
2431
2432         /* Check for valid size */
2433         if (size < sizeof(*rule)) {
2434                 kprintf("ipfw: rule too short\n");
2435                 return EINVAL;
2436         }
2437         l = IOC_RULESIZE(rule);
2438         if (l != size) {
2439                 kprintf("ipfw: size mismatch (have %d want %d)\n", size, l);
2440                 return EINVAL;
2441         }
2442
2443         /*
2444          * Now go for the individual checks. Very simple ones, basically only
2445          * instruction sizes.
2446          */
2447         for (l = rule->cmd_len, cmd = rule->cmd; l > 0;
2448              l -= cmdlen, cmd += cmdlen) {
2449                 cmdlen = F_LEN(cmd);
2450                 if (cmdlen > l) {
2451                         kprintf("ipfw: opcode %d size truncated\n",
2452                             cmd->opcode);
2453                         return EINVAL;
2454                 }
2455                 DEB(kprintf("ipfw: opcode %d\n", cmd->opcode);)
2456                 switch (cmd->opcode) {
2457                 case O_NOP:
2458                 case O_PROBE_STATE:
2459                 case O_KEEP_STATE:
2460                 case O_PROTO:
2461                 case O_IP_SRC_ME:
2462                 case O_IP_DST_ME:
2463                 case O_LAYER2:
2464                 case O_IN:
2465                 case O_FRAG:
2466                 case O_IPOPT:
2467                 case O_IPLEN:
2468                 case O_IPID:
2469                 case O_IPTOS:
2470                 case O_IPPRECEDENCE:
2471                 case O_IPTTL:
2472                 case O_IPVER:
2473                 case O_TCPWIN:
2474                 case O_TCPFLAGS:
2475                 case O_TCPOPTS:
2476                 case O_ESTAB:
2477                         if (cmdlen != F_INSN_SIZE(ipfw_insn))
2478                                 goto bad_size;
2479                         break;
2480
2481                 case O_UID:
2482                 case O_GID:
2483                 case O_IP_SRC:
2484                 case O_IP_DST:
2485                 case O_TCPSEQ:
2486                 case O_TCPACK:
2487                 case O_PROB:
2488                 case O_ICMPTYPE:
2489                         if (cmdlen != F_INSN_SIZE(ipfw_insn_u32))
2490                                 goto bad_size;
2491                         break;
2492
2493                 case O_LIMIT:
2494                         if (cmdlen != F_INSN_SIZE(ipfw_insn_limit))
2495                                 goto bad_size;
2496                         break;
2497
2498                 case O_LOG:
2499                         if (cmdlen != F_INSN_SIZE(ipfw_insn_log))
2500                                 goto bad_size;
2501
2502                         ((ipfw_insn_log *)cmd)->log_left =
2503                             ((ipfw_insn_log *)cmd)->max_log;
2504
2505                         break;
2506
2507                 case O_IP_SRC_MASK:
2508                 case O_IP_DST_MASK:
2509                         if (cmdlen != F_INSN_SIZE(ipfw_insn_ip))
2510                                 goto bad_size;
2511                         if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) {
2512                                 kprintf("ipfw: opcode %d, useless rule\n",
2513                                         cmd->opcode);
2514                                 return EINVAL;
2515                         }
2516                         break;
2517
2518                 case O_IP_SRC_SET:
2519                 case O_IP_DST_SET:
2520                         if (cmd->arg1 == 0 || cmd->arg1 > 256) {
2521                                 kprintf("ipfw: invalid set size %d\n",
2522                                         cmd->arg1);
2523                                 return EINVAL;
2524                         }
2525                         if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) +
2526                             (cmd->arg1+31)/32 )
2527                                 goto bad_size;
2528                         break;
2529
2530                 case O_MACADDR2:
2531                         if (cmdlen != F_INSN_SIZE(ipfw_insn_mac))
2532                                 goto bad_size;
2533                         break;
2534
2535                 case O_MAC_TYPE:
2536                 case O_IP_SRCPORT:
2537                 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */
2538                         if (cmdlen < 2 || cmdlen > 31)
2539                                 goto bad_size;
2540                         break;
2541
2542                 case O_RECV:
2543                 case O_XMIT:
2544                 case O_VIA:
2545                         if (cmdlen != F_INSN_SIZE(ipfw_insn_if))
2546                                 goto bad_size;
2547                         break;
2548
2549                 case O_PIPE:
2550                 case O_QUEUE:
2551                         if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe))
2552                                 goto bad_size;
2553                         goto check_action;
2554
2555                 case O_FORWARD_IP:
2556                         if (cmdlen != F_INSN_SIZE(ipfw_insn_sa))
2557                                 goto bad_size;
2558                         goto check_action;
2559
2560                 case O_FORWARD_MAC: /* XXX not implemented yet */
2561                 case O_CHECK_STATE:
2562                 case O_COUNT:
2563                 case O_ACCEPT:
2564                 case O_DENY:
2565                 case O_REJECT:
2566                 case O_SKIPTO:
2567                 case O_DIVERT:
2568                 case O_TEE:
2569                         if (cmdlen != F_INSN_SIZE(ipfw_insn))
2570                                 goto bad_size;
2571 check_action:
2572                         if (have_action) {
2573                                 kprintf("ipfw: opcode %d, multiple actions"
2574                                         " not allowed\n",
2575                                         cmd->opcode);
2576                                 return EINVAL;
2577                         }
2578                         have_action = 1;
2579                         if (l != cmdlen) {
2580                                 kprintf("ipfw: opcode %d, action must be"
2581                                         " last opcode\n",
2582                                         cmd->opcode);
2583                                 return EINVAL;
2584                         }
2585                         break;
2586                 default:
2587                         kprintf("ipfw: opcode %d, unknown opcode\n",
2588                                 cmd->opcode);
2589                         return EINVAL;
2590                 }
2591         }
2592         if (have_action == 0) {
2593                 kprintf("ipfw: missing action\n");
2594                 return EINVAL;
2595         }
2596         return 0;
2597
2598 bad_size:
2599         kprintf("ipfw: opcode %d size %d wrong\n",
2600                 cmd->opcode, cmdlen);
2601         return EINVAL;
2602 }
2603
2604 static int
2605 ipfw_ctl_add_rule(struct sockopt *sopt)
2606 {
2607         struct ipfw_ioc_rule *ioc_rule;
2608         size_t size;
2609         int error;
2610
2611         size = sopt->sopt_valsize;
2612         if ((size > (sizeof(uint32_t) * IPFW_RULE_SIZE_MAX)) ||
2613             (size < sizeof(*ioc_rule))) {
2614                 return EINVAL;
2615         }
2616         if (size != (sizeof(uint32_t) * IPFW_RULE_SIZE_MAX)) {
2617                 sopt->sopt_val = krealloc(sopt->sopt_val, sizeof(uint32_t) *
2618                                           IPFW_RULE_SIZE_MAX, M_TEMP, M_WAITOK);
2619         }
2620         ioc_rule = sopt->sopt_val;
2621
2622         error = ipfw_ctl_check_rule(ioc_rule, size);
2623         if (error)
2624                 return error;
2625
2626         error = ipfw_add_rule(&layer3_chain, ioc_rule);
2627         if (error)
2628                 return error;
2629
2630         if (sopt->sopt_dir == SOPT_GET) {
2631                 sopt->sopt_valsize = IOC_RULESIZE(ioc_rule);
2632         }
2633         return 0;
2634 }
2635
2636 static void *
2637 ipfw_copy_rule(const struct ip_fw *rule, struct ipfw_ioc_rule *ioc_rule)
2638 {
2639         ioc_rule->act_ofs = rule->act_ofs;
2640         ioc_rule->cmd_len = rule->cmd_len;
2641         ioc_rule->rulenum = rule->rulenum;
2642         ioc_rule->set = rule->set;
2643         ioc_rule->usr_flags = rule->usr_flags;
2644
2645         ioc_rule->set_disable = set_disable;
2646         ioc_rule->static_count = static_count;
2647         ioc_rule->static_len = static_ioc_len;
2648
2649         ioc_rule->pcnt = rule->pcnt;
2650         ioc_rule->bcnt = rule->bcnt;
2651         ioc_rule->timestamp = rule->timestamp;
2652
2653         bcopy(rule->cmd, ioc_rule->cmd, ioc_rule->cmd_len * 4 /* XXX */);
2654
2655         return ((uint8_t *)ioc_rule + IOC_RULESIZE(ioc_rule));
2656 }
2657
2658 static void
2659 ipfw_copy_state(const ipfw_dyn_rule *dyn_rule,
2660                 struct ipfw_ioc_state *ioc_state)
2661 {
2662         const struct ipfw_flow_id *id;
2663         struct ipfw_ioc_flowid *ioc_id;
2664
2665         ioc_state->expire = TIME_LEQ(dyn_rule->expire, time_second) ?
2666                             0 : dyn_rule->expire - time_second;
2667         ioc_state->pcnt = dyn_rule->pcnt;
2668         ioc_state->bcnt = dyn_rule->bcnt;
2669
2670         ioc_state->dyn_type = dyn_rule->dyn_type;
2671         ioc_state->count = dyn_rule->count;
2672
2673         ioc_state->rulenum = dyn_rule->rule->rulenum;
2674
2675         id = &dyn_rule->id;
2676         ioc_id = &ioc_state->id;
2677
2678         ioc_id->type = ETHERTYPE_IP;
2679         ioc_id->u.ip.dst_ip = id->dst_ip;
2680         ioc_id->u.ip.src_ip = id->src_ip;
2681         ioc_id->u.ip.dst_port = id->dst_port;
2682         ioc_id->u.ip.src_port = id->src_port;
2683         ioc_id->u.ip.proto = id->proto;
2684 }
2685
2686 static int
2687 ipfw_ctl_get_rules(struct sockopt *sopt)
2688 {
2689         struct ip_fw *rule;
2690         void *bp;
2691         size_t size;
2692
2693         /*
2694          * pass up a copy of the current rules. Static rules
2695          * come first (the last of which has number IPFW_DEFAULT_RULE),
2696          * followed by a possibly empty list of dynamic rule.
2697          */
2698         crit_enter();
2699
2700         size = static_ioc_len;  /* size of static rules */
2701         if (ipfw_dyn_v)         /* add size of dyn.rules */
2702                 size += (dyn_count * sizeof(struct ipfw_ioc_state));
2703
2704         if (sopt->sopt_valsize < size) {
2705                 /* short length, no need to return incomplete rules */
2706                 /* XXX: if superuser, no need to zero buffer */
2707                 bzero(sopt->sopt_val, sopt->sopt_valsize);
2708                 return 0;
2709         }
2710         bp = sopt->sopt_val;
2711
2712         for (rule = layer3_chain; rule; rule = rule->next)
2713                 bp = ipfw_copy_rule(rule, bp);
2714
2715         if (ipfw_dyn_v) {
2716                 struct ipfw_ioc_state *ioc_state;
2717                 int i;
2718
2719                 ioc_state = bp;
2720                 for (i = 0; i < curr_dyn_buckets; i++) {
2721                         ipfw_dyn_rule *p;
2722
2723                         for (p = ipfw_dyn_v[i]; p != NULL;
2724                              p = p->next, ioc_state++)
2725                                 ipfw_copy_state(p, ioc_state);
2726                 }
2727         }
2728
2729         crit_exit();
2730
2731         sopt->sopt_valsize = size;
2732         return 0;
2733 }
2734
2735 /**
2736  * {set|get}sockopt parser.
2737  */
2738 static int
2739 ipfw_ctl(struct sockopt *sopt)
2740 {
2741         int error, rulenum;
2742         uint32_t *masks;
2743         size_t size;
2744
2745         /*
2746          * Disallow modifications in really-really secure mode, but still allow
2747          * the logging counters to be reset.
2748          */
2749         if (sopt->sopt_name == IP_FW_ADD ||
2750             (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) {
2751                 if (securelevel >= 3)
2752                         return EPERM;
2753         }
2754
2755         error = 0;
2756
2757         switch (sopt->sopt_name) {
2758         case IP_FW_GET:
2759                 error = ipfw_ctl_get_rules(sopt);
2760                 break;
2761
2762         case IP_FW_FLUSH:
2763                 /*
2764                  * Normally we cannot release the lock on each iteration.
2765                  * We could do it here only because we start from the head all
2766                  * the times so there is no risk of missing some entries.
2767                  * On the other hand, the risk is that we end up with
2768                  * a very inconsistent ruleset, so better keep the lock
2769                  * around the whole cycle.
2770                  *
2771                  * XXX this code can be improved by resetting the head of
2772                  * the list to point to the default rule, and then freeing
2773                  * the old list without the need for a lock.
2774                  */
2775
2776                 crit_enter();
2777                 free_chain(&layer3_chain, 0 /* keep default rule */);
2778                 crit_exit();
2779                 break;
2780
2781         case IP_FW_ADD:
2782                 error = ipfw_ctl_add_rule(sopt);
2783                 break;
2784
2785         case IP_FW_DEL:
2786                 /*
2787                  * IP_FW_DEL is used for deleting single rules or sets,
2788                  * and (ab)used to atomically manipulate sets. Argument size
2789                  * is used to distinguish between the two:
2790                  *    sizeof(uint32_t)
2791                  *      delete single rule or set of rules,
2792                  *      or reassign rules (or sets) to a different set.
2793                  *    2*sizeof(uint32_t)
2794                  *      atomic disable/enable sets.
2795                  *      first uint32_t contains sets to be disabled,
2796                  *      second uint32_t contains sets to be enabled.
2797                  */
2798                 masks = sopt->sopt_val;
2799                 size = sopt->sopt_valsize;
2800                 if (size == sizeof(*masks)) {
2801                         /*
2802                          * Delete or reassign static rule
2803                          */
2804                         error = del_entry(&layer3_chain, masks[0]);
2805                 } else if (size == (2 * sizeof(*masks))) {
2806                         /*
2807                          * Set enable/disable
2808                          */
2809                         crit_enter();
2810
2811                         set_disable =
2812                             (set_disable | masks[0]) & ~masks[1] &
2813                             ~(1 << 31); /* set 31 always enabled */
2814
2815                         crit_exit();
2816                 } else {
2817                         error = EINVAL;
2818                 }
2819                 break;
2820
2821         case IP_FW_ZERO:
2822         case IP_FW_RESETLOG: /* argument is an int, the rule number */
2823                 rulenum=0;
2824
2825                 if (sopt->sopt_val != 0) {
2826                     error = soopt_to_kbuf(sopt, &rulenum,
2827                             sizeof(int), sizeof(int));
2828                     if (error)
2829                         break;
2830                 }
2831                 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG);
2832                 break;
2833
2834         default:
2835                 kprintf("ipfw_ctl invalid option %d\n", sopt->sopt_name);
2836                 error = EINVAL;
2837         }
2838
2839         return error;
2840 }
2841
2842 /*
2843  * This procedure is only used to handle keepalives. It is invoked
2844  * every dyn_keepalive_period
2845  */
2846 static void
2847 ipfw_tick(void * __unused unused)
2848 {
2849         int i;
2850         ipfw_dyn_rule *q;
2851
2852         if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0)
2853                 goto done;
2854
2855         crit_enter();
2856         for (i = 0 ; i < curr_dyn_buckets ; i++) {
2857                 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) {
2858                         if (q->dyn_type == O_LIMIT_PARENT)
2859                                 continue;
2860                         if (q->id.proto != IPPROTO_TCP)
2861                                 continue;
2862                         if ( (q->state & BOTH_SYN) != BOTH_SYN)
2863                                 continue;
2864                         if (TIME_LEQ( time_second+dyn_keepalive_interval,
2865                             q->expire))
2866                                 continue;       /* too early */
2867                         if (TIME_LEQ(q->expire, time_second))
2868                                 continue;       /* too late, rule expired */
2869
2870                         send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
2871                         send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0);
2872                 }
2873         }
2874         crit_exit();
2875 done:
2876         callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz,
2877                       ipfw_tick, NULL);
2878 }
2879
2880 static void
2881 ipfw_init_default_rule(struct ip_fw **head)
2882 {
2883         struct ip_fw *def_rule;
2884
2885         KKASSERT(*head == NULL);
2886
2887         def_rule = kmalloc(sizeof(*def_rule), M_IPFW, M_WAITOK | M_ZERO);
2888
2889         def_rule->act_ofs = 0;
2890         def_rule->rulenum = IPFW_DEFAULT_RULE;
2891         def_rule->cmd_len = 1;
2892         def_rule->set = 31;
2893
2894         def_rule->cmd[0].len = 1;
2895 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
2896         def_rule->cmd[0].opcode = O_ACCEPT;
2897 #else
2898         def_rule->cmd[0].opcode = O_DENY;
2899 #endif
2900
2901         def_rule->refcnt = 1;
2902
2903         *head = def_rule;
2904         ipfw_inc_static_count(def_rule);
2905
2906         /* Install the default rule */
2907         ip_fw_default_rule = def_rule;
2908 }
2909
2910 static void
2911 ipfw_init(void)
2912 {
2913         ip_fw_chk_ptr = ipfw_chk;
2914         ip_fw_ctl_ptr = ipfw_ctl;
2915         ip_fw_dn_io_ptr = ipfw_dummynet_io;
2916
2917         layer3_chain = NULL;
2918         ipfw_init_default_rule(&layer3_chain);
2919
2920         kprintf("ipfw2 initialized, divert %s, "
2921                 "rule-based forwarding enabled, default to %s, logging ",
2922 #ifdef IPDIVERT
2923                 "enabled",
2924 #else
2925                 "disabled",
2926 #endif
2927                 ip_fw_default_rule->cmd[0].opcode == O_ACCEPT ?
2928                 "accept" : "deny");
2929
2930 #ifdef IPFIREWALL_VERBOSE
2931         fw_verbose = 1;
2932 #endif
2933 #ifdef IPFIREWALL_VERBOSE_LIMIT
2934         verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
2935 #endif
2936         if (fw_verbose == 0)
2937                 kprintf("disabled\n");
2938         else if (verbose_limit == 0)
2939                 kprintf("unlimited\n");
2940         else
2941                 kprintf("limited to %d packets/entry by default\n",
2942                     verbose_limit);
2943         callout_init(&ipfw_timeout_h);
2944         callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL);
2945 }
2946
2947 static int
2948 ipfw_modevent(module_t mod, int type, void *unused)
2949 {
2950         int err = 0;
2951
2952         switch (type) {
2953         case MOD_LOAD:
2954                 crit_enter();
2955                 if (IPFW_LOADED) {
2956                         crit_exit();
2957                         kprintf("IP firewall already loaded\n");
2958                         err = EEXIST;
2959                 } else {
2960                         ipfw_init();
2961                         crit_exit();
2962                 }
2963                 break;
2964
2965         case MOD_UNLOAD:
2966 #ifndef KLD_MODULE
2967                 kprintf("ipfw statically compiled, cannot unload\n");
2968                 err = EBUSY;
2969 #else
2970                 if (ipfw_refcnt != 0) {
2971                         err = EBUSY;
2972                         break;
2973                 }
2974
2975                 crit_enter();
2976                 callout_stop(&ipfw_timeout_h);
2977                 ip_fw_chk_ptr = NULL;
2978                 ip_fw_ctl_ptr = NULL;
2979                 ip_fw_dn_io_ptr = NULL;
2980                 free_chain(&layer3_chain, 1 /* kill default rule */);
2981                 crit_exit();
2982                 kprintf("IP firewall unloaded\n");
2983 #endif
2984                 break;
2985         default:
2986                 break;
2987         }
2988         return err;
2989 }
2990
2991 static moduledata_t ipfwmod = {
2992         "ipfw",
2993         ipfw_modevent,
2994         0
2995 };
2996 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_END, SI_ORDER_ANY);
2997 MODULE_VERSION(ipfw, 1);