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 1.14 2004/09/17 08:25:30 dillon Exp $ 27 */ 28 29 #define DEB(x) 30 #define DDB(x) x 31 32 /* 33 * Implement IP packet firewall (new version) 34 */ 35 36 #if !defined(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 #if IPFW2 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/malloc.h> 50 #include <sys/mbuf.h> 51 #include <sys/kernel.h> 52 #include <sys/proc.h> 53 #include <sys/socket.h> 54 #include <sys/socketvar.h> 55 #include <sys/sysctl.h> 56 #include <sys/syslog.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 * XXX This one should go in sys/mbuf.h. It is used to avoid that 81 * a firewall-generated packet loops forever through the firewall. 82 */ 83 #ifndef M_SKIP_FIREWALL 84 #define M_SKIP_FIREWALL 0x4000 85 #endif 86 87 /* 88 * set_disable contains one bit per set value (0..31). 89 * If the bit is set, all rules with the corresponding set 90 * are disabled. Set 31 is reserved for the default rule 91 * and CANNOT be disabled. 92 */ 93 static u_int32_t set_disable; 94 95 static int fw_verbose; 96 static int verbose_limit; 97 98 static struct callout ipfw_timeout_h; 99 #define IPFW_DEFAULT_RULE 65535 100 101 /* 102 * list of rules for layer 3 103 */ 104 static struct ip_fw *layer3_chain; 105 106 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 107 108 static int fw_debug = 1; 109 static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 110 111 #ifdef SYSCTL_NODE 112 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 113 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, 114 &fw_enable, 0, "Enable ipfw"); 115 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 116 &autoinc_step, 0, "Rule number autincrement step"); 117 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, 118 &fw_one_pass, 0, 119 "Only do a single pass through ipfw when using dummynet(4)"); 120 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 121 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 122 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, 123 &fw_verbose, 0, "Log matches to ipfw rules"); 124 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 125 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 126 127 /* 128 * Description of dynamic rules. 129 * 130 * Dynamic rules are stored in lists accessed through a hash table 131 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 132 * be modified through the sysctl variable dyn_buckets which is 133 * updated when the table becomes empty. 134 * 135 * XXX currently there is only one list, ipfw_dyn. 136 * 137 * When a packet is received, its address fields are first masked 138 * with the mask defined for the rule, then hashed, then matched 139 * against the entries in the corresponding list. 140 * Dynamic rules can be used for different purposes: 141 * + stateful rules; 142 * + enforcing limits on the number of sessions; 143 * + in-kernel NAT (not implemented yet) 144 * 145 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 146 * measured in seconds and depending on the flags. 147 * 148 * The total number of dynamic rules is stored in dyn_count. 149 * The max number of dynamic rules is dyn_max. When we reach 150 * the maximum number of rules we do not create anymore. This is 151 * done to avoid consuming too much memory, but also too much 152 * time when searching on each packet (ideally, we should try instead 153 * to put a limit on the length of the list on each bucket...). 154 * 155 * Each dynamic rule holds a pointer to the parent ipfw rule so 156 * we know what action to perform. Dynamic rules are removed when 157 * the parent rule is deleted. XXX we should make them survive. 158 * 159 * There are some limitations with dynamic rules -- we do not 160 * obey the 'randomized match', and we do not do multiple 161 * passes through the firewall. XXX check the latter!!! 162 */ 163 static ipfw_dyn_rule **ipfw_dyn_v = NULL; 164 static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 165 static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 166 167 /* 168 * Timeouts for various events in handing dynamic rules. 169 */ 170 static u_int32_t dyn_ack_lifetime = 300; 171 static u_int32_t dyn_syn_lifetime = 20; 172 static u_int32_t dyn_fin_lifetime = 1; 173 static u_int32_t dyn_rst_lifetime = 1; 174 static u_int32_t dyn_udp_lifetime = 10; 175 static u_int32_t dyn_short_lifetime = 5; 176 177 /* 178 * Keepalives are sent if dyn_keepalive is set. They are sent every 179 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 180 * seconds of lifetime of a rule. 181 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 182 * than dyn_keepalive_period. 183 */ 184 185 static u_int32_t dyn_keepalive_interval = 20; 186 static u_int32_t dyn_keepalive_period = 5; 187 static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 188 189 static u_int32_t static_count; /* # of static rules */ 190 static u_int32_t static_len; /* size in bytes of static rules */ 191 static u_int32_t dyn_count; /* # of dynamic rules */ 192 static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 193 194 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 195 &dyn_buckets, 0, "Number of dyn. buckets"); 196 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 197 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 198 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 199 &dyn_count, 0, "Number of dyn. rules"); 200 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 201 &dyn_max, 0, "Max number of dyn. rules"); 202 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 203 &static_count, 0, "Number of static rules"); 204 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 205 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 206 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 207 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 208 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 209 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 210 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 211 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 212 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 213 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 214 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 215 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 216 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 217 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 218 219 #endif /* SYSCTL_NODE */ 220 221 222 static ip_fw_chk_t ipfw_chk; 223 224 ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 225 226 /* 227 * This macro maps an ip pointer into a layer3 header pointer of type T 228 */ 229 #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 230 231 static __inline int 232 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 233 { 234 int type = L3HDR(struct icmp,ip)->icmp_type; 235 236 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 237 } 238 239 #define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 240 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 241 242 static int 243 is_icmp_query(struct ip *ip) 244 { 245 int type = L3HDR(struct icmp, ip)->icmp_type; 246 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 247 } 248 #undef TT 249 250 /* 251 * The following checks use two arrays of 8 or 16 bits to store the 252 * bits that we want set or clear, respectively. They are in the 253 * low and high half of cmd->arg1 or cmd->d[0]. 254 * 255 * We scan options and store the bits we find set. We succeed if 256 * 257 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 258 * 259 * The code is sometimes optimized not to store additional variables. 260 */ 261 262 static int 263 flags_match(ipfw_insn *cmd, u_int8_t bits) 264 { 265 u_char want_clear; 266 bits = ~bits; 267 268 if ( ((cmd->arg1 & 0xff) & bits) != 0) 269 return 0; /* some bits we want set were clear */ 270 want_clear = (cmd->arg1 >> 8) & 0xff; 271 if ( (want_clear & bits) != want_clear) 272 return 0; /* some bits we want clear were set */ 273 return 1; 274 } 275 276 static int 277 ipopts_match(struct ip *ip, ipfw_insn *cmd) 278 { 279 int optlen, bits = 0; 280 u_char *cp = (u_char *)(ip + 1); 281 int x = (ip->ip_hl << 2) - sizeof (struct ip); 282 283 for (; x > 0; x -= optlen, cp += optlen) { 284 int opt = cp[IPOPT_OPTVAL]; 285 286 if (opt == IPOPT_EOL) 287 break; 288 if (opt == IPOPT_NOP) 289 optlen = 1; 290 else { 291 optlen = cp[IPOPT_OLEN]; 292 if (optlen <= 0 || optlen > x) 293 return 0; /* invalid or truncated */ 294 } 295 switch (opt) { 296 297 default: 298 break; 299 300 case IPOPT_LSRR: 301 bits |= IP_FW_IPOPT_LSRR; 302 break; 303 304 case IPOPT_SSRR: 305 bits |= IP_FW_IPOPT_SSRR; 306 break; 307 308 case IPOPT_RR: 309 bits |= IP_FW_IPOPT_RR; 310 break; 311 312 case IPOPT_TS: 313 bits |= IP_FW_IPOPT_TS; 314 break; 315 } 316 } 317 return (flags_match(cmd, bits)); 318 } 319 320 static int 321 tcpopts_match(struct ip *ip, ipfw_insn *cmd) 322 { 323 int optlen, bits = 0; 324 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 325 u_char *cp = (u_char *)(tcp + 1); 326 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 327 328 for (; x > 0; x -= optlen, cp += optlen) { 329 int opt = cp[0]; 330 if (opt == TCPOPT_EOL) 331 break; 332 if (opt == TCPOPT_NOP) 333 optlen = 1; 334 else { 335 optlen = cp[1]; 336 if (optlen <= 0) 337 break; 338 } 339 340 switch (opt) { 341 342 default: 343 break; 344 345 case TCPOPT_MAXSEG: 346 bits |= IP_FW_TCPOPT_MSS; 347 break; 348 349 case TCPOPT_WINDOW: 350 bits |= IP_FW_TCPOPT_WINDOW; 351 break; 352 353 case TCPOPT_SACK_PERMITTED: 354 case TCPOPT_SACK: 355 bits |= IP_FW_TCPOPT_SACK; 356 break; 357 358 case TCPOPT_TIMESTAMP: 359 bits |= IP_FW_TCPOPT_TS; 360 break; 361 362 case TCPOPT_CC: 363 case TCPOPT_CCNEW: 364 case TCPOPT_CCECHO: 365 bits |= IP_FW_TCPOPT_CC; 366 break; 367 } 368 } 369 return (flags_match(cmd, bits)); 370 } 371 372 static int 373 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 374 { 375 if (ifp == NULL) /* no iface with this packet, match fails */ 376 return 0; 377 /* Check by name or by IP address */ 378 if (cmd->name[0] != '\0') { /* match by name */ 379 /* Check name */ 380 if (cmd->p.glob) { 381 if (fnmatch(cmd->name, ifp->if_xname, 0) == 0) 382 return(1); 383 } else { 384 if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) 385 return(1); 386 } 387 } else { 388 struct ifaddr *ia; 389 390 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 391 if (ia->ifa_addr == NULL) 392 continue; 393 if (ia->ifa_addr->sa_family != AF_INET) 394 continue; 395 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 396 (ia->ifa_addr))->sin_addr.s_addr) 397 return(1); /* match */ 398 } 399 } 400 return(0); /* no match, fail ... */ 401 } 402 403 static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 404 405 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 406 #define SNP(buf) buf, sizeof(buf) 407 408 /* 409 * We enter here when we have a rule with O_LOG. 410 * XXX this function alone takes about 2Kbytes of code! 411 */ 412 static void 413 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 414 struct mbuf *m, struct ifnet *oif) 415 { 416 char *action; 417 int limit_reached = 0; 418 char action2[40], proto[48], fragment[28]; 419 420 fragment[0] = '\0'; 421 proto[0] = '\0'; 422 423 if (f == NULL) { /* bogus pkt */ 424 if (verbose_limit != 0 && norule_counter >= verbose_limit) 425 return; 426 norule_counter++; 427 if (norule_counter == verbose_limit) 428 limit_reached = verbose_limit; 429 action = "Refuse"; 430 } else { /* O_LOG is the first action, find the real one */ 431 ipfw_insn *cmd = ACTION_PTR(f); 432 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 433 434 if (l->max_log != 0 && l->log_left == 0) 435 return; 436 l->log_left--; 437 if (l->log_left == 0) 438 limit_reached = l->max_log; 439 cmd += F_LEN(cmd); /* point to first action */ 440 if (cmd->opcode == O_PROB) 441 cmd += F_LEN(cmd); 442 443 action = action2; 444 switch (cmd->opcode) { 445 case O_DENY: 446 action = "Deny"; 447 break; 448 449 case O_REJECT: 450 if (cmd->arg1==ICMP_REJECT_RST) 451 action = "Reset"; 452 else if (cmd->arg1==ICMP_UNREACH_HOST) 453 action = "Reject"; 454 else 455 snprintf(SNPARGS(action2, 0), "Unreach %d", 456 cmd->arg1); 457 break; 458 459 case O_ACCEPT: 460 action = "Accept"; 461 break; 462 case O_COUNT: 463 action = "Count"; 464 break; 465 case O_DIVERT: 466 snprintf(SNPARGS(action2, 0), "Divert %d", 467 cmd->arg1); 468 break; 469 case O_TEE: 470 snprintf(SNPARGS(action2, 0), "Tee %d", 471 cmd->arg1); 472 break; 473 case O_SKIPTO: 474 snprintf(SNPARGS(action2, 0), "SkipTo %d", 475 cmd->arg1); 476 break; 477 case O_PIPE: 478 snprintf(SNPARGS(action2, 0), "Pipe %d", 479 cmd->arg1); 480 break; 481 case O_QUEUE: 482 snprintf(SNPARGS(action2, 0), "Queue %d", 483 cmd->arg1); 484 break; 485 case O_FORWARD_IP: { 486 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 487 int len; 488 489 len = snprintf(SNPARGS(action2, 0), "Forward to %s", 490 inet_ntoa(sa->sa.sin_addr)); 491 if (sa->sa.sin_port) 492 snprintf(SNPARGS(action2, len), ":%d", 493 sa->sa.sin_port); 494 } 495 break; 496 default: 497 action = "UNKNOWN"; 498 break; 499 } 500 } 501 502 if (hlen == 0) { /* non-ip */ 503 snprintf(SNPARGS(proto, 0), "MAC"); 504 } else { 505 struct ip *ip = mtod(m, struct ip *); 506 /* these three are all aliases to the same thing */ 507 struct icmp *const icmp = L3HDR(struct icmp, ip); 508 struct tcphdr *const tcp = (struct tcphdr *)icmp; 509 struct udphdr *const udp = (struct udphdr *)icmp; 510 511 int ip_off, offset, ip_len; 512 513 int len; 514 515 if (eh != NULL) { /* layer 2 packets are as on the wire */ 516 ip_off = ntohs(ip->ip_off); 517 ip_len = ntohs(ip->ip_len); 518 } else { 519 ip_off = ip->ip_off; 520 ip_len = ip->ip_len; 521 } 522 offset = ip_off & IP_OFFMASK; 523 switch (ip->ip_p) { 524 case IPPROTO_TCP: 525 len = snprintf(SNPARGS(proto, 0), "TCP %s", 526 inet_ntoa(ip->ip_src)); 527 if (offset == 0) 528 snprintf(SNPARGS(proto, len), ":%d %s:%d", 529 ntohs(tcp->th_sport), 530 inet_ntoa(ip->ip_dst), 531 ntohs(tcp->th_dport)); 532 else 533 snprintf(SNPARGS(proto, len), " %s", 534 inet_ntoa(ip->ip_dst)); 535 break; 536 537 case IPPROTO_UDP: 538 len = snprintf(SNPARGS(proto, 0), "UDP %s", 539 inet_ntoa(ip->ip_src)); 540 if (offset == 0) 541 snprintf(SNPARGS(proto, len), ":%d %s:%d", 542 ntohs(udp->uh_sport), 543 inet_ntoa(ip->ip_dst), 544 ntohs(udp->uh_dport)); 545 else 546 snprintf(SNPARGS(proto, len), " %s", 547 inet_ntoa(ip->ip_dst)); 548 break; 549 550 case IPPROTO_ICMP: 551 if (offset == 0) 552 len = snprintf(SNPARGS(proto, 0), 553 "ICMP:%u.%u ", 554 icmp->icmp_type, icmp->icmp_code); 555 else 556 len = snprintf(SNPARGS(proto, 0), "ICMP "); 557 len += snprintf(SNPARGS(proto, len), "%s", 558 inet_ntoa(ip->ip_src)); 559 snprintf(SNPARGS(proto, len), " %s", 560 inet_ntoa(ip->ip_dst)); 561 break; 562 563 default: 564 len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 565 inet_ntoa(ip->ip_src)); 566 snprintf(SNPARGS(proto, len), " %s", 567 inet_ntoa(ip->ip_dst)); 568 break; 569 } 570 571 if (ip_off & (IP_MF | IP_OFFMASK)) 572 snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 573 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 574 offset << 3, 575 (ip_off & IP_MF) ? "+" : ""); 576 } 577 if (oif || m->m_pkthdr.rcvif) 578 log(LOG_SECURITY | LOG_INFO, 579 "ipfw: %d %s %s %s via %s%s\n", 580 f ? f->rulenum : -1, 581 action, proto, oif ? "out" : "in", 582 oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 583 fragment); 584 else 585 log(LOG_SECURITY | LOG_INFO, 586 "ipfw: %d %s %s [no if info]%s\n", 587 f ? f->rulenum : -1, 588 action, proto, fragment); 589 if (limit_reached) 590 log(LOG_SECURITY | LOG_NOTICE, 591 "ipfw: limit %d reached on entry %d\n", 592 limit_reached, f ? f->rulenum : -1); 593 } 594 595 /* 596 * IMPORTANT: the hash function for dynamic rules must be commutative 597 * in source and destination (ip,port), because rules are bidirectional 598 * and we want to find both in the same bucket. 599 */ 600 static __inline int 601 hash_packet(struct ipfw_flow_id *id) 602 { 603 u_int32_t i; 604 605 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 606 i &= (curr_dyn_buckets - 1); 607 return i; 608 } 609 610 /** 611 * unlink a dynamic rule from a chain. prev is a pointer to 612 * the previous one, q is a pointer to the rule to delete, 613 * head is a pointer to the head of the queue. 614 * Modifies q and potentially also head. 615 */ 616 #define UNLINK_DYN_RULE(prev, head, q) { \ 617 ipfw_dyn_rule *old_q = q; \ 618 \ 619 /* remove a refcount to the parent */ \ 620 if (q->dyn_type == O_LIMIT) \ 621 q->parent->count--; \ 622 DEB(printf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \ 623 (q->id.src_ip), (q->id.src_port), \ 624 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 625 if (prev != NULL) \ 626 prev->next = q = q->next; \ 627 else \ 628 head = q = q->next; \ 629 dyn_count--; \ 630 free(old_q, M_IPFW); } 631 632 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 633 634 /** 635 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 636 * 637 * If keep_me == NULL, rules are deleted even if not expired, 638 * otherwise only expired rules are removed. 639 * 640 * The value of the second parameter is also used to point to identify 641 * a rule we absolutely do not want to remove (e.g. because we are 642 * holding a reference to it -- this is the case with O_LIMIT_PARENT 643 * rules). The pointer is only used for comparison, so any non-null 644 * value will do. 645 */ 646 static void 647 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 648 { 649 static u_int32_t last_remove = 0; 650 651 #define FORCE (keep_me == NULL) 652 653 ipfw_dyn_rule *prev, *q; 654 int i, pass = 0, max_pass = 0; 655 656 if (ipfw_dyn_v == NULL || dyn_count == 0) 657 return; 658 /* do not expire more than once per second, it is useless */ 659 if (!FORCE && last_remove == time_second) 660 return; 661 last_remove = time_second; 662 663 /* 664 * because O_LIMIT refer to parent rules, during the first pass only 665 * remove child and mark any pending LIMIT_PARENT, and remove 666 * them in a second pass. 667 */ 668 next_pass: 669 for (i = 0 ; i < curr_dyn_buckets ; i++) { 670 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 671 /* 672 * Logic can become complex here, so we split tests. 673 */ 674 if (q == keep_me) 675 goto next; 676 if (rule != NULL && rule != q->rule) 677 goto next; /* not the one we are looking for */ 678 if (q->dyn_type == O_LIMIT_PARENT) { 679 /* 680 * handle parent in the second pass, 681 * record we need one. 682 */ 683 max_pass = 1; 684 if (pass == 0) 685 goto next; 686 if (FORCE && q->count != 0 ) { 687 /* XXX should not happen! */ 688 printf( "OUCH! cannot remove rule," 689 " count %d\n", q->count); 690 } 691 } else { 692 if (!FORCE && 693 !TIME_LEQ( q->expire, time_second )) 694 goto next; 695 } 696 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 697 continue; 698 next: 699 prev=q; 700 q=q->next; 701 } 702 } 703 if (pass++ < max_pass) 704 goto next_pass; 705 } 706 707 708 /** 709 * lookup a dynamic rule. 710 */ 711 static ipfw_dyn_rule * 712 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 713 struct tcphdr *tcp) 714 { 715 /* 716 * stateful ipfw extensions. 717 * Lookup into dynamic session queue 718 */ 719 #define MATCH_REVERSE 0 720 #define MATCH_FORWARD 1 721 #define MATCH_NONE 2 722 #define MATCH_UNKNOWN 3 723 int i, dir = MATCH_NONE; 724 ipfw_dyn_rule *prev, *q=NULL; 725 726 if (ipfw_dyn_v == NULL) 727 goto done; /* not found */ 728 i = hash_packet( pkt ); 729 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 730 if (q->dyn_type == O_LIMIT_PARENT) 731 goto next; 732 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 733 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 734 continue; 735 } 736 if ( pkt->proto == q->id.proto) { 737 if (pkt->src_ip == q->id.src_ip && 738 pkt->dst_ip == q->id.dst_ip && 739 pkt->src_port == q->id.src_port && 740 pkt->dst_port == q->id.dst_port ) { 741 dir = MATCH_FORWARD; 742 break; 743 } 744 if (pkt->src_ip == q->id.dst_ip && 745 pkt->dst_ip == q->id.src_ip && 746 pkt->src_port == q->id.dst_port && 747 pkt->dst_port == q->id.src_port ) { 748 dir = MATCH_REVERSE; 749 break; 750 } 751 } 752 next: 753 prev = q; 754 q = q->next; 755 } 756 if (q == NULL) 757 goto done; /* q = NULL, not found */ 758 759 if ( prev != NULL) { /* found and not in front */ 760 prev->next = q->next; 761 q->next = ipfw_dyn_v[i]; 762 ipfw_dyn_v[i] = q; 763 } 764 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 765 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 766 767 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 768 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 769 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 770 switch (q->state) { 771 case TH_SYN: /* opening */ 772 q->expire = time_second + dyn_syn_lifetime; 773 break; 774 775 case BOTH_SYN: /* move to established */ 776 case BOTH_SYN | TH_FIN : /* one side tries to close */ 777 case BOTH_SYN | (TH_FIN << 8) : 778 if (tcp) { 779 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 780 u_int32_t ack = ntohl(tcp->th_ack); 781 if (dir == MATCH_FORWARD) { 782 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 783 q->ack_fwd = ack; 784 else { /* ignore out-of-sequence */ 785 break; 786 } 787 } else { 788 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 789 q->ack_rev = ack; 790 else { /* ignore out-of-sequence */ 791 break; 792 } 793 } 794 } 795 q->expire = time_second + dyn_ack_lifetime; 796 break; 797 798 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 799 if (dyn_fin_lifetime >= dyn_keepalive_period) 800 dyn_fin_lifetime = dyn_keepalive_period - 1; 801 q->expire = time_second + dyn_fin_lifetime; 802 break; 803 804 default: 805 #if 0 806 /* 807 * reset or some invalid combination, but can also 808 * occur if we use keep-state the wrong way. 809 */ 810 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 811 printf("invalid state: 0x%x\n", q->state); 812 #endif 813 if (dyn_rst_lifetime >= dyn_keepalive_period) 814 dyn_rst_lifetime = dyn_keepalive_period - 1; 815 q->expire = time_second + dyn_rst_lifetime; 816 break; 817 } 818 } else if (pkt->proto == IPPROTO_UDP) { 819 q->expire = time_second + dyn_udp_lifetime; 820 } else { 821 /* other protocols */ 822 q->expire = time_second + dyn_short_lifetime; 823 } 824 done: 825 if (match_direction) 826 *match_direction = dir; 827 return q; 828 } 829 830 static void 831 realloc_dynamic_table(void) 832 { 833 /* 834 * Try reallocation, make sure we have a power of 2 and do 835 * not allow more than 64k entries. In case of overflow, 836 * default to 1024. 837 */ 838 839 if (dyn_buckets > 65536) 840 dyn_buckets = 1024; 841 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 842 dyn_buckets = curr_dyn_buckets; /* reset */ 843 return; 844 } 845 curr_dyn_buckets = dyn_buckets; 846 if (ipfw_dyn_v != NULL) 847 free(ipfw_dyn_v, M_IPFW); 848 for (;;) { 849 ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 850 M_IPFW, M_WAITOK | M_ZERO); 851 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 852 break; 853 curr_dyn_buckets /= 2; 854 } 855 } 856 857 /** 858 * Install state of type 'type' for a dynamic session. 859 * The hash table contains two type of rules: 860 * - regular rules (O_KEEP_STATE) 861 * - rules for sessions with limited number of sess per user 862 * (O_LIMIT). When they are created, the parent is 863 * increased by 1, and decreased on delete. In this case, 864 * the third parameter is the parent rule and not the chain. 865 * - "parent" rules for the above (O_LIMIT_PARENT). 866 */ 867 static ipfw_dyn_rule * 868 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 869 { 870 ipfw_dyn_rule *r; 871 int i; 872 873 if (ipfw_dyn_v == NULL || 874 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 875 realloc_dynamic_table(); 876 if (ipfw_dyn_v == NULL) 877 return NULL; /* failed ! */ 878 } 879 i = hash_packet(id); 880 881 r = malloc(sizeof *r, M_IPFW, M_WAITOK | M_ZERO); 882 if (r == NULL) { 883 printf ("sorry cannot allocate state\n"); 884 return NULL; 885 } 886 887 /* increase refcount on parent, and set pointer */ 888 if (dyn_type == O_LIMIT) { 889 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 890 if ( parent->dyn_type != O_LIMIT_PARENT) 891 panic("invalid parent"); 892 parent->count++; 893 r->parent = parent; 894 rule = parent->rule; 895 } 896 897 r->id = *id; 898 r->expire = time_second + dyn_syn_lifetime; 899 r->rule = rule; 900 r->dyn_type = dyn_type; 901 r->pcnt = r->bcnt = 0; 902 r->count = 0; 903 904 r->bucket = i; 905 r->next = ipfw_dyn_v[i]; 906 ipfw_dyn_v[i] = r; 907 dyn_count++; 908 DEB(printf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 909 dyn_type, 910 (r->id.src_ip), (r->id.src_port), 911 (r->id.dst_ip), (r->id.dst_port), 912 dyn_count ); ) 913 return r; 914 } 915 916 /** 917 * lookup dynamic parent rule using pkt and rule as search keys. 918 * If the lookup fails, then install one. 919 */ 920 static ipfw_dyn_rule * 921 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 922 { 923 ipfw_dyn_rule *q; 924 int i; 925 926 if (ipfw_dyn_v) { 927 i = hash_packet( pkt ); 928 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 929 if (q->dyn_type == O_LIMIT_PARENT && 930 rule== q->rule && 931 pkt->proto == q->id.proto && 932 pkt->src_ip == q->id.src_ip && 933 pkt->dst_ip == q->id.dst_ip && 934 pkt->src_port == q->id.src_port && 935 pkt->dst_port == q->id.dst_port) { 936 q->expire = time_second + dyn_short_lifetime; 937 DEB(printf("lookup_dyn_parent found 0x%p\n",q);) 938 return q; 939 } 940 } 941 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 942 } 943 944 /** 945 * Install dynamic state for rule type cmd->o.opcode 946 * 947 * Returns 1 (failure) if state is not installed because of errors or because 948 * session limitations are enforced. 949 */ 950 static int 951 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 952 struct ip_fw_args *args) 953 { 954 static int last_log; 955 956 ipfw_dyn_rule *q; 957 958 DEB(printf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", 959 cmd->o.opcode, 960 (args->f_id.src_ip), (args->f_id.src_port), 961 (args->f_id.dst_ip), (args->f_id.dst_port) );) 962 963 q = lookup_dyn_rule(&args->f_id, NULL, NULL); 964 965 if (q != NULL) { /* should never occur */ 966 if (last_log != time_second) { 967 last_log = time_second; 968 printf(" install_state: entry already present, done\n"); 969 } 970 return 0; 971 } 972 973 if (dyn_count >= dyn_max) 974 /* 975 * Run out of slots, try to remove any expired rule. 976 */ 977 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 978 979 if (dyn_count >= dyn_max) { 980 if (last_log != time_second) { 981 last_log = time_second; 982 printf("install_state: Too many dynamic rules\n"); 983 } 984 return 1; /* cannot install, notify caller */ 985 } 986 987 switch (cmd->o.opcode) { 988 case O_KEEP_STATE: /* bidir rule */ 989 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 990 break; 991 992 case O_LIMIT: /* limit number of sessions */ 993 { 994 u_int16_t limit_mask = cmd->limit_mask; 995 struct ipfw_flow_id id; 996 ipfw_dyn_rule *parent; 997 998 DEB(printf("installing dyn-limit rule %d\n", cmd->conn_limit);) 999 1000 id.dst_ip = id.src_ip = 0; 1001 id.dst_port = id.src_port = 0; 1002 id.proto = args->f_id.proto; 1003 1004 if (limit_mask & DYN_SRC_ADDR) 1005 id.src_ip = args->f_id.src_ip; 1006 if (limit_mask & DYN_DST_ADDR) 1007 id.dst_ip = args->f_id.dst_ip; 1008 if (limit_mask & DYN_SRC_PORT) 1009 id.src_port = args->f_id.src_port; 1010 if (limit_mask & DYN_DST_PORT) 1011 id.dst_port = args->f_id.dst_port; 1012 parent = lookup_dyn_parent(&id, rule); 1013 if (parent == NULL) { 1014 printf("add parent failed\n"); 1015 return 1; 1016 } 1017 if (parent->count >= cmd->conn_limit) { 1018 /* 1019 * See if we can remove some expired rule. 1020 */ 1021 remove_dyn_rule(rule, parent); 1022 if (parent->count >= cmd->conn_limit) { 1023 if (fw_verbose && last_log != time_second) { 1024 last_log = time_second; 1025 log(LOG_SECURITY | LOG_DEBUG, 1026 "drop session, too many entries\n"); 1027 } 1028 return 1; 1029 } 1030 } 1031 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1032 } 1033 break; 1034 default: 1035 printf("unknown dynamic rule type %u\n", cmd->o.opcode); 1036 return 1; 1037 } 1038 lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1039 return 0; 1040 } 1041 1042 /* 1043 * Transmit a TCP packet, containing either a RST or a keepalive. 1044 * When flags & TH_RST, we are sending a RST packet, because of a 1045 * "reset" action matched the packet. 1046 * Otherwise we are sending a keepalive, and flags & TH_ 1047 */ 1048 static void 1049 send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1050 { 1051 struct mbuf *m; 1052 struct ip *ip; 1053 struct tcphdr *tcp; 1054 struct route sro; /* fake route */ 1055 1056 MGETHDR(m, MB_DONTWAIT, MT_HEADER); 1057 if (m == 0) 1058 return; 1059 m->m_pkthdr.rcvif = (struct ifnet *)0; 1060 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1061 m->m_data += max_linkhdr; 1062 1063 ip = mtod(m, struct ip *); 1064 bzero(ip, m->m_len); 1065 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1066 ip->ip_p = IPPROTO_TCP; 1067 tcp->th_off = 5; 1068 /* 1069 * Assume we are sending a RST (or a keepalive in the reverse 1070 * direction), swap src and destination addresses and ports. 1071 */ 1072 ip->ip_src.s_addr = htonl(id->dst_ip); 1073 ip->ip_dst.s_addr = htonl(id->src_ip); 1074 tcp->th_sport = htons(id->dst_port); 1075 tcp->th_dport = htons(id->src_port); 1076 if (flags & TH_RST) { /* we are sending a RST */ 1077 if (flags & TH_ACK) { 1078 tcp->th_seq = htonl(ack); 1079 tcp->th_ack = htonl(0); 1080 tcp->th_flags = TH_RST; 1081 } else { 1082 if (flags & TH_SYN) 1083 seq++; 1084 tcp->th_seq = htonl(0); 1085 tcp->th_ack = htonl(seq); 1086 tcp->th_flags = TH_RST | TH_ACK; 1087 } 1088 } else { 1089 /* 1090 * We are sending a keepalive. flags & TH_SYN determines 1091 * the direction, forward if set, reverse if clear. 1092 * NOTE: seq and ack are always assumed to be correct 1093 * as set by the caller. This may be confusing... 1094 */ 1095 if (flags & TH_SYN) { 1096 /* 1097 * we have to rewrite the correct addresses! 1098 */ 1099 ip->ip_dst.s_addr = htonl(id->dst_ip); 1100 ip->ip_src.s_addr = htonl(id->src_ip); 1101 tcp->th_dport = htons(id->dst_port); 1102 tcp->th_sport = htons(id->src_port); 1103 } 1104 tcp->th_seq = htonl(seq); 1105 tcp->th_ack = htonl(ack); 1106 tcp->th_flags = TH_ACK; 1107 } 1108 /* 1109 * set ip_len to the payload size so we can compute 1110 * the tcp checksum on the pseudoheader 1111 * XXX check this, could save a couple of words ? 1112 */ 1113 ip->ip_len = htons(sizeof(struct tcphdr)); 1114 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1115 /* 1116 * now fill fields left out earlier 1117 */ 1118 ip->ip_ttl = ip_defttl; 1119 ip->ip_len = m->m_pkthdr.len; 1120 bzero (&sro, sizeof (sro)); 1121 ip_rtaddr(ip->ip_dst, &sro); 1122 m->m_flags |= M_SKIP_FIREWALL; 1123 ip_output(m, NULL, &sro, 0, NULL, NULL); 1124 if (sro.ro_rt) 1125 RTFREE(sro.ro_rt); 1126 } 1127 1128 /* 1129 * sends a reject message, consuming the mbuf passed as an argument. 1130 */ 1131 static void 1132 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1133 { 1134 1135 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1136 /* We need the IP header in host order for icmp_error(). */ 1137 if (args->eh != NULL) { 1138 struct ip *ip = mtod(args->m, struct ip *); 1139 ip->ip_len = ntohs(ip->ip_len); 1140 ip->ip_off = ntohs(ip->ip_off); 1141 } 1142 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1143 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1144 struct tcphdr *const tcp = 1145 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1146 if ( (tcp->th_flags & TH_RST) == 0) 1147 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1148 ntohl(tcp->th_ack), 1149 tcp->th_flags | TH_RST); 1150 m_freem(args->m); 1151 } else 1152 m_freem(args->m); 1153 args->m = NULL; 1154 } 1155 1156 /** 1157 * 1158 * Given an ip_fw *, lookup_next_rule will return a pointer 1159 * to the next rule, which can be either the jump 1160 * target (for skipto instructions) or the next one in the list (in 1161 * all other cases including a missing jump target). 1162 * The result is also written in the "next_rule" field of the rule. 1163 * Backward jumps are not allowed, so start looking from the next 1164 * rule... 1165 * 1166 * This never returns NULL -- in case we do not have an exact match, 1167 * the next rule is returned. When the ruleset is changed, 1168 * pointers are flushed so we are always correct. 1169 */ 1170 1171 static struct ip_fw * 1172 lookup_next_rule(struct ip_fw *me) 1173 { 1174 struct ip_fw *rule = NULL; 1175 ipfw_insn *cmd; 1176 1177 /* look for action, in case it is a skipto */ 1178 cmd = ACTION_PTR(me); 1179 if (cmd->opcode == O_LOG) 1180 cmd += F_LEN(cmd); 1181 if ( cmd->opcode == O_SKIPTO ) 1182 for (rule = me->next; rule ; rule = rule->next) 1183 if (rule->rulenum >= cmd->arg1) 1184 break; 1185 if (rule == NULL) /* failure or not a skipto */ 1186 rule = me->next; 1187 me->next_rule = rule; 1188 return rule; 1189 } 1190 1191 /* 1192 * The main check routine for the firewall. 1193 * 1194 * All arguments are in args so we can modify them and return them 1195 * back to the caller. 1196 * 1197 * Parameters: 1198 * 1199 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1200 * Starts with the IP header. 1201 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1202 * args->oif Outgoing interface, or NULL if packet is incoming. 1203 * The incoming interface is in the mbuf. (in) 1204 * args->divert_rule (in/out) 1205 * Skip up to the first rule past this rule number; 1206 * upon return, non-zero port number for divert or tee. 1207 * 1208 * args->rule Pointer to the last matching rule (in/out) 1209 * args->next_hop Socket we are forwarding to (out). 1210 * args->f_id Addresses grabbed from the packet (out) 1211 * 1212 * Return value: 1213 * 1214 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1215 * 0 The packet is to be accepted and routed normally OR 1216 * the packet was denied/rejected and has been dropped; 1217 * in the latter case, *m is equal to NULL upon return. 1218 * port Divert the packet to port, with these caveats: 1219 * 1220 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1221 * of diverting it (ie, 'ipfw tee'). 1222 * 1223 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1224 * 16 bits as a dummynet pipe number instead of diverting 1225 */ 1226 1227 static int 1228 ipfw_chk(struct ip_fw_args *args) 1229 { 1230 /* 1231 * Local variables hold state during the processing of a packet. 1232 * 1233 * IMPORTANT NOTE: to speed up the processing of rules, there 1234 * are some assumption on the values of the variables, which 1235 * are documented here. Should you change them, please check 1236 * the implementation of the various instructions to make sure 1237 * that they still work. 1238 * 1239 * args->eh The MAC header. It is non-null for a layer2 1240 * packet, it is NULL for a layer-3 packet. 1241 * 1242 * m | args->m Pointer to the mbuf, as received from the caller. 1243 * It may change if ipfw_chk() does an m_pullup, or if it 1244 * consumes the packet because it calls send_reject(). 1245 * XXX This has to change, so that ipfw_chk() never modifies 1246 * or consumes the buffer. 1247 * ip is simply an alias of the value of m, and it is kept 1248 * in sync with it (the packet is supposed to start with 1249 * the ip header). 1250 */ 1251 struct mbuf *m = args->m; 1252 struct ip *ip = mtod(m, struct ip *); 1253 1254 /* 1255 * oif | args->oif If NULL, ipfw_chk has been called on the 1256 * inbound path (ether_input, bdg_forward, ip_input). 1257 * If non-NULL, ipfw_chk has been called on the outbound path 1258 * (ether_output, ip_output). 1259 */ 1260 struct ifnet *oif = args->oif; 1261 1262 struct ip_fw *f = NULL; /* matching rule */ 1263 int retval = 0; 1264 1265 /* 1266 * hlen The length of the IPv4 header. 1267 * hlen >0 means we have an IPv4 packet. 1268 */ 1269 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1270 1271 /* 1272 * offset The offset of a fragment. offset != 0 means that 1273 * we have a fragment at this offset of an IPv4 packet. 1274 * offset == 0 means that (if this is an IPv4 packet) 1275 * this is the first or only fragment. 1276 */ 1277 u_short offset = 0; 1278 1279 /* 1280 * Local copies of addresses. They are only valid if we have 1281 * an IP packet. 1282 * 1283 * proto The protocol. Set to 0 for non-ip packets, 1284 * or to the protocol read from the packet otherwise. 1285 * proto != 0 means that we have an IPv4 packet. 1286 * 1287 * src_port, dst_port port numbers, in HOST format. Only 1288 * valid for TCP and UDP packets. 1289 * 1290 * src_ip, dst_ip ip addresses, in NETWORK format. 1291 * Only valid for IPv4 packets. 1292 */ 1293 u_int8_t proto; 1294 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1295 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1296 u_int16_t ip_len=0; 1297 int dyn_dir = MATCH_UNKNOWN; 1298 ipfw_dyn_rule *q = NULL; 1299 1300 if (m->m_flags & M_SKIP_FIREWALL) 1301 return 0; /* accept */ 1302 /* 1303 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1304 * MATCH_NONE when checked and not matched (q = NULL), 1305 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1306 */ 1307 1308 if (args->eh == NULL || /* layer 3 packet */ 1309 ( m->m_pkthdr.len >= sizeof(struct ip) && 1310 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1311 hlen = ip->ip_hl << 2; 1312 1313 /* 1314 * Collect parameters into local variables for faster matching. 1315 */ 1316 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1317 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1318 goto after_ip_checks; 1319 } 1320 1321 proto = args->f_id.proto = ip->ip_p; 1322 src_ip = ip->ip_src; 1323 dst_ip = ip->ip_dst; 1324 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1325 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1326 ip_len = ntohs(ip->ip_len); 1327 } else { 1328 offset = ip->ip_off & IP_OFFMASK; 1329 ip_len = ip->ip_len; 1330 } 1331 1332 #define PULLUP_TO(len) \ 1333 do { \ 1334 if ((m)->m_len < (len)) { \ 1335 args->m = m = m_pullup(m, (len)); \ 1336 if (m == 0) \ 1337 goto pullup_failed; \ 1338 ip = mtod(m, struct ip *); \ 1339 } \ 1340 } while (0) 1341 1342 if (offset == 0) { 1343 switch (proto) { 1344 case IPPROTO_TCP: 1345 { 1346 struct tcphdr *tcp; 1347 1348 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1349 tcp = L3HDR(struct tcphdr, ip); 1350 dst_port = tcp->th_dport; 1351 src_port = tcp->th_sport; 1352 args->f_id.flags = tcp->th_flags; 1353 } 1354 break; 1355 1356 case IPPROTO_UDP: 1357 { 1358 struct udphdr *udp; 1359 1360 PULLUP_TO(hlen + sizeof(struct udphdr)); 1361 udp = L3HDR(struct udphdr, ip); 1362 dst_port = udp->uh_dport; 1363 src_port = udp->uh_sport; 1364 } 1365 break; 1366 1367 case IPPROTO_ICMP: 1368 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1369 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1370 break; 1371 1372 default: 1373 break; 1374 } 1375 #undef PULLUP_TO 1376 } 1377 1378 args->f_id.src_ip = ntohl(src_ip.s_addr); 1379 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1380 args->f_id.src_port = src_port = ntohs(src_port); 1381 args->f_id.dst_port = dst_port = ntohs(dst_port); 1382 1383 after_ip_checks: 1384 if (args->rule) { 1385 /* 1386 * Packet has already been tagged. Look for the next rule 1387 * to restart processing. 1388 * 1389 * If fw_one_pass != 0 then just accept it. 1390 * XXX should not happen here, but optimized out in 1391 * the caller. 1392 */ 1393 if (fw_one_pass) 1394 return 0; 1395 1396 f = args->rule->next_rule; 1397 if (f == NULL) 1398 f = lookup_next_rule(args->rule); 1399 } else { 1400 /* 1401 * Find the starting rule. It can be either the first 1402 * one, or the one after divert_rule if asked so. 1403 */ 1404 int skipto = args->divert_rule; 1405 1406 f = layer3_chain; 1407 if (args->eh == NULL && skipto != 0) { 1408 if (skipto >= IPFW_DEFAULT_RULE) 1409 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1410 while (f && f->rulenum <= skipto) 1411 f = f->next; 1412 if (f == NULL) /* drop packet */ 1413 return(IP_FW_PORT_DENY_FLAG); 1414 } 1415 } 1416 args->divert_rule = 0; /* reset to avoid confusion later */ 1417 1418 /* 1419 * Now scan the rules, and parse microinstructions for each rule. 1420 */ 1421 for (; f; f = f->next) { 1422 int l, cmdlen; 1423 ipfw_insn *cmd; 1424 int skip_or; /* skip rest of OR block */ 1425 1426 again: 1427 if (set_disable & (1 << f->set) ) 1428 continue; 1429 1430 skip_or = 0; 1431 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1432 l -= cmdlen, cmd += cmdlen) { 1433 int match; 1434 1435 /* 1436 * check_body is a jump target used when we find a 1437 * CHECK_STATE, and need to jump to the body of 1438 * the target rule. 1439 */ 1440 1441 check_body: 1442 cmdlen = F_LEN(cmd); 1443 /* 1444 * An OR block (insn_1 || .. || insn_n) has the 1445 * F_OR bit set in all but the last instruction. 1446 * The first match will set "skip_or", and cause 1447 * the following instructions to be skipped until 1448 * past the one with the F_OR bit clear. 1449 */ 1450 if (skip_or) { /* skip this instruction */ 1451 if ((cmd->len & F_OR) == 0) 1452 skip_or = 0; /* next one is good */ 1453 continue; 1454 } 1455 match = 0; /* set to 1 if we succeed */ 1456 1457 switch (cmd->opcode) { 1458 /* 1459 * The first set of opcodes compares the packet's 1460 * fields with some pattern, setting 'match' if a 1461 * match is found. At the end of the loop there is 1462 * logic to deal with F_NOT and F_OR flags associated 1463 * with the opcode. 1464 */ 1465 case O_NOP: 1466 match = 1; 1467 break; 1468 1469 case O_FORWARD_MAC: 1470 printf("ipfw: opcode %d unimplemented\n", 1471 cmd->opcode); 1472 break; 1473 1474 case O_GID: 1475 case O_UID: 1476 /* 1477 * We only check offset == 0 && proto != 0, 1478 * as this ensures that we have an IPv4 1479 * packet with the ports info. 1480 */ 1481 if (offset!=0) 1482 break; 1483 { 1484 struct inpcbinfo *pi; 1485 int wildcard; 1486 struct inpcb *pcb; 1487 1488 if (proto == IPPROTO_TCP) { 1489 wildcard = 0; 1490 pi = &tcbinfo[mycpu->gd_cpuid]; 1491 } else if (proto == IPPROTO_UDP) { 1492 wildcard = 1; 1493 pi = &udbinfo; 1494 } else 1495 break; 1496 1497 pcb = (oif) ? 1498 in_pcblookup_hash(pi, 1499 dst_ip, htons(dst_port), 1500 src_ip, htons(src_port), 1501 wildcard, oif) : 1502 in_pcblookup_hash(pi, 1503 src_ip, htons(src_port), 1504 dst_ip, htons(dst_port), 1505 wildcard, NULL); 1506 1507 if (pcb == NULL || pcb->inp_socket == NULL) 1508 break; 1509 #if defined(__DragonFly__) || (defined(__FreeBSD__) && __FreeBSD_version < 500034) 1510 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1511 #endif 1512 if (cmd->opcode == O_UID) { 1513 match = 1514 !socheckuid(pcb->inp_socket, 1515 (uid_t)((ipfw_insn_u32 *)cmd)->d[0]); 1516 } else { 1517 match = groupmember( 1518 (uid_t)((ipfw_insn_u32 *)cmd)->d[0], 1519 pcb->inp_socket->so_cred); 1520 } 1521 } 1522 break; 1523 1524 case O_RECV: 1525 match = iface_match(m->m_pkthdr.rcvif, 1526 (ipfw_insn_if *)cmd); 1527 break; 1528 1529 case O_XMIT: 1530 match = iface_match(oif, (ipfw_insn_if *)cmd); 1531 break; 1532 1533 case O_VIA: 1534 match = iface_match(oif ? oif : 1535 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1536 break; 1537 1538 case O_MACADDR2: 1539 if (args->eh != NULL) { /* have MAC header */ 1540 u_int32_t *want = (u_int32_t *) 1541 ((ipfw_insn_mac *)cmd)->addr; 1542 u_int32_t *mask = (u_int32_t *) 1543 ((ipfw_insn_mac *)cmd)->mask; 1544 u_int32_t *hdr = (u_int32_t *)args->eh; 1545 1546 match = 1547 ( want[0] == (hdr[0] & mask[0]) && 1548 want[1] == (hdr[1] & mask[1]) && 1549 want[2] == (hdr[2] & mask[2]) ); 1550 } 1551 break; 1552 1553 case O_MAC_TYPE: 1554 if (args->eh != NULL) { 1555 u_int16_t t = 1556 ntohs(args->eh->ether_type); 1557 u_int16_t *p = 1558 ((ipfw_insn_u16 *)cmd)->ports; 1559 int i; 1560 1561 for (i = cmdlen - 1; !match && i>0; 1562 i--, p += 2) 1563 match = (t>=p[0] && t<=p[1]); 1564 } 1565 break; 1566 1567 case O_FRAG: 1568 match = (hlen > 0 && offset != 0); 1569 break; 1570 1571 case O_IN: /* "out" is "not in" */ 1572 match = (oif == NULL); 1573 break; 1574 1575 case O_LAYER2: 1576 match = (args->eh != NULL); 1577 break; 1578 1579 case O_PROTO: 1580 /* 1581 * We do not allow an arg of 0 so the 1582 * check of "proto" only suffices. 1583 */ 1584 match = (proto == cmd->arg1); 1585 break; 1586 1587 case O_IP_SRC: 1588 match = (hlen > 0 && 1589 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1590 src_ip.s_addr); 1591 break; 1592 1593 case O_IP_SRC_MASK: 1594 match = (hlen > 0 && 1595 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1596 (src_ip.s_addr & 1597 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1598 break; 1599 1600 case O_IP_SRC_ME: 1601 if (hlen > 0) { 1602 struct ifnet *tif; 1603 1604 INADDR_TO_IFP(src_ip, tif); 1605 match = (tif != NULL); 1606 } 1607 break; 1608 1609 case O_IP_DST_SET: 1610 case O_IP_SRC_SET: 1611 if (hlen > 0) { 1612 u_int32_t *d = (u_int32_t *)(cmd+1); 1613 u_int32_t addr = 1614 cmd->opcode == O_IP_DST_SET ? 1615 args->f_id.dst_ip : 1616 args->f_id.src_ip; 1617 1618 if (addr < d[0]) 1619 break; 1620 addr -= d[0]; /* subtract base */ 1621 match = (addr < cmd->arg1) && 1622 ( d[ 1 + (addr>>5)] & 1623 (1<<(addr & 0x1f)) ); 1624 } 1625 break; 1626 1627 case O_IP_DST: 1628 match = (hlen > 0 && 1629 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1630 dst_ip.s_addr); 1631 break; 1632 1633 case O_IP_DST_MASK: 1634 match = (hlen > 0) && 1635 (((ipfw_insn_ip *)cmd)->addr.s_addr == 1636 (dst_ip.s_addr & 1637 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1638 break; 1639 1640 case O_IP_DST_ME: 1641 if (hlen > 0) { 1642 struct ifnet *tif; 1643 1644 INADDR_TO_IFP(dst_ip, tif); 1645 match = (tif != NULL); 1646 } 1647 break; 1648 1649 case O_IP_SRCPORT: 1650 case O_IP_DSTPORT: 1651 /* 1652 * offset == 0 && proto != 0 is enough 1653 * to guarantee that we have an IPv4 1654 * packet with port info. 1655 */ 1656 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1657 && offset == 0) { 1658 u_int16_t x = 1659 (cmd->opcode == O_IP_SRCPORT) ? 1660 src_port : dst_port ; 1661 u_int16_t *p = 1662 ((ipfw_insn_u16 *)cmd)->ports; 1663 int i; 1664 1665 for (i = cmdlen - 1; !match && i>0; 1666 i--, p += 2) 1667 match = (x>=p[0] && x<=p[1]); 1668 } 1669 break; 1670 1671 case O_ICMPTYPE: 1672 match = (offset == 0 && proto==IPPROTO_ICMP && 1673 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1674 break; 1675 1676 case O_IPOPT: 1677 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1678 break; 1679 1680 case O_IPVER: 1681 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1682 break; 1683 1684 case O_IPTTL: 1685 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl); 1686 break; 1687 1688 case O_IPID: 1689 match = (hlen > 0 && 1690 cmd->arg1 == ntohs(ip->ip_id)); 1691 break; 1692 1693 case O_IPLEN: 1694 match = (hlen > 0 && cmd->arg1 == ip_len); 1695 break; 1696 1697 case O_IPPRECEDENCE: 1698 match = (hlen > 0 && 1699 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1700 break; 1701 1702 case O_IPTOS: 1703 match = (hlen > 0 && 1704 flags_match(cmd, ip->ip_tos)); 1705 break; 1706 1707 case O_TCPFLAGS: 1708 match = (proto == IPPROTO_TCP && offset == 0 && 1709 flags_match(cmd, 1710 L3HDR(struct tcphdr,ip)->th_flags)); 1711 break; 1712 1713 case O_TCPOPTS: 1714 match = (proto == IPPROTO_TCP && offset == 0 && 1715 tcpopts_match(ip, cmd)); 1716 break; 1717 1718 case O_TCPSEQ: 1719 match = (proto == IPPROTO_TCP && offset == 0 && 1720 ((ipfw_insn_u32 *)cmd)->d[0] == 1721 L3HDR(struct tcphdr,ip)->th_seq); 1722 break; 1723 1724 case O_TCPACK: 1725 match = (proto == IPPROTO_TCP && offset == 0 && 1726 ((ipfw_insn_u32 *)cmd)->d[0] == 1727 L3HDR(struct tcphdr,ip)->th_ack); 1728 break; 1729 1730 case O_TCPWIN: 1731 match = (proto == IPPROTO_TCP && offset == 0 && 1732 cmd->arg1 == 1733 L3HDR(struct tcphdr,ip)->th_win); 1734 break; 1735 1736 case O_ESTAB: 1737 /* reject packets which have SYN only */ 1738 /* XXX should i also check for TH_ACK ? */ 1739 match = (proto == IPPROTO_TCP && offset == 0 && 1740 (L3HDR(struct tcphdr,ip)->th_flags & 1741 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1742 break; 1743 1744 case O_LOG: 1745 if (fw_verbose) 1746 ipfw_log(f, hlen, args->eh, m, oif); 1747 match = 1; 1748 break; 1749 1750 case O_PROB: 1751 match = (random()<((ipfw_insn_u32 *)cmd)->d[0]); 1752 break; 1753 1754 /* 1755 * The second set of opcodes represents 'actions', 1756 * i.e. the terminal part of a rule once the packet 1757 * matches all previous patterns. 1758 * Typically there is only one action for each rule, 1759 * and the opcode is stored at the end of the rule 1760 * (but there are exceptions -- see below). 1761 * 1762 * In general, here we set retval and terminate the 1763 * outer loop (would be a 'break 3' in some language, 1764 * but we need to do a 'goto done'). 1765 * 1766 * Exceptions: 1767 * O_COUNT and O_SKIPTO actions: 1768 * instead of terminating, we jump to the next rule 1769 * ('goto next_rule', equivalent to a 'break 2'), 1770 * or to the SKIPTO target ('goto again' after 1771 * having set f, cmd and l), respectively. 1772 * 1773 * O_LIMIT and O_KEEP_STATE: these opcodes are 1774 * not real 'actions', and are stored right 1775 * before the 'action' part of the rule. 1776 * These opcodes try to install an entry in the 1777 * state tables; if successful, we continue with 1778 * the next opcode (match=1; break;), otherwise 1779 * the packet * must be dropped 1780 * ('goto done' after setting retval); 1781 * 1782 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1783 * cause a lookup of the state table, and a jump 1784 * to the 'action' part of the parent rule 1785 * ('goto check_body') if an entry is found, or 1786 * (CHECK_STATE only) a jump to the next rule if 1787 * the entry is not found ('goto next_rule'). 1788 * The result of the lookup is cached to make 1789 * further instances of these opcodes are 1790 * effectively NOPs. 1791 */ 1792 case O_LIMIT: 1793 case O_KEEP_STATE: 1794 if (install_state(f, 1795 (ipfw_insn_limit *)cmd, args)) { 1796 retval = IP_FW_PORT_DENY_FLAG; 1797 goto done; /* error/limit violation */ 1798 } 1799 match = 1; 1800 break; 1801 1802 case O_PROBE_STATE: 1803 case O_CHECK_STATE: 1804 /* 1805 * dynamic rules are checked at the first 1806 * keep-state or check-state occurrence, 1807 * with the result being stored in dyn_dir. 1808 * The compiler introduces a PROBE_STATE 1809 * instruction for us when we have a 1810 * KEEP_STATE (because PROBE_STATE needs 1811 * to be run first). 1812 */ 1813 if (dyn_dir == MATCH_UNKNOWN && 1814 (q = lookup_dyn_rule(&args->f_id, 1815 &dyn_dir, proto == IPPROTO_TCP ? 1816 L3HDR(struct tcphdr, ip) : NULL)) 1817 != NULL) { 1818 /* 1819 * Found dynamic entry, update stats 1820 * and jump to the 'action' part of 1821 * the parent rule. 1822 */ 1823 q->pcnt++; 1824 q->bcnt += ip_len; 1825 f = q->rule; 1826 cmd = ACTION_PTR(f); 1827 l = f->cmd_len - f->act_ofs; 1828 goto check_body; 1829 } 1830 /* 1831 * Dynamic entry not found. If CHECK_STATE, 1832 * skip to next rule, if PROBE_STATE just 1833 * ignore and continue with next opcode. 1834 */ 1835 if (cmd->opcode == O_CHECK_STATE) 1836 goto next_rule; 1837 match = 1; 1838 break; 1839 1840 case O_ACCEPT: 1841 retval = 0; /* accept */ 1842 goto done; 1843 1844 case O_PIPE: 1845 case O_QUEUE: 1846 args->rule = f; /* report matching rule */ 1847 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 1848 goto done; 1849 1850 case O_DIVERT: 1851 case O_TEE: 1852 if (args->eh) /* not on layer 2 */ 1853 break; 1854 args->divert_rule = f->rulenum; 1855 retval = (cmd->opcode == O_DIVERT) ? 1856 cmd->arg1 : 1857 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 1858 goto done; 1859 1860 case O_COUNT: 1861 case O_SKIPTO: 1862 f->pcnt++; /* update stats */ 1863 f->bcnt += ip_len; 1864 f->timestamp = time_second; 1865 if (cmd->opcode == O_COUNT) 1866 goto next_rule; 1867 /* handle skipto */ 1868 if (f->next_rule == NULL) 1869 lookup_next_rule(f); 1870 f = f->next_rule; 1871 goto again; 1872 1873 case O_REJECT: 1874 /* 1875 * Drop the packet and send a reject notice 1876 * if the packet is not ICMP (or is an ICMP 1877 * query), and it is not multicast/broadcast. 1878 */ 1879 if (hlen > 0 && 1880 (proto != IPPROTO_ICMP || 1881 is_icmp_query(ip)) && 1882 !(m->m_flags & (M_BCAST|M_MCAST)) && 1883 !IN_MULTICAST(ntohl(dst_ip.s_addr))) { 1884 send_reject(args, cmd->arg1, 1885 offset,ip_len); 1886 m = args->m; 1887 } 1888 /* FALLTHROUGH */ 1889 case O_DENY: 1890 retval = IP_FW_PORT_DENY_FLAG; 1891 goto done; 1892 1893 case O_FORWARD_IP: 1894 if (args->eh) /* not valid on layer2 pkts */ 1895 break; 1896 if (!q || dyn_dir == MATCH_FORWARD) 1897 args->next_hop = 1898 &((ipfw_insn_sa *)cmd)->sa; 1899 retval = 0; 1900 goto done; 1901 1902 default: 1903 panic("-- unknown opcode %d\n", cmd->opcode); 1904 } /* end of switch() on opcodes */ 1905 1906 if (cmd->len & F_NOT) 1907 match = !match; 1908 1909 if (match) { 1910 if (cmd->len & F_OR) 1911 skip_or = 1; 1912 } else { 1913 if (!(cmd->len & F_OR)) /* not an OR block, */ 1914 break; /* try next rule */ 1915 } 1916 1917 } /* end of inner for, scan opcodes */ 1918 1919 next_rule:; /* try next rule */ 1920 1921 } /* end of outer for, scan rules */ 1922 printf("+++ ipfw: ouch!, skip past end of rules, denying packet\n"); 1923 return(IP_FW_PORT_DENY_FLAG); 1924 1925 done: 1926 /* Update statistics */ 1927 f->pcnt++; 1928 f->bcnt += ip_len; 1929 f->timestamp = time_second; 1930 return retval; 1931 1932 pullup_failed: 1933 if (fw_verbose) 1934 printf("pullup failed\n"); 1935 return(IP_FW_PORT_DENY_FLAG); 1936 } 1937 1938 /* 1939 * When a rule is added/deleted, clear the next_rule pointers in all rules. 1940 * These will be reconstructed on the fly as packets are matched. 1941 * Must be called at splimp(). 1942 */ 1943 static void 1944 flush_rule_ptrs(void) 1945 { 1946 struct ip_fw *rule; 1947 1948 for (rule = layer3_chain; rule; rule = rule->next) 1949 rule->next_rule = NULL; 1950 } 1951 1952 /* 1953 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 1954 * pipe/queue, or to all of them (match == NULL). 1955 * Must be called at splimp(). 1956 */ 1957 void 1958 flush_pipe_ptrs(struct dn_flow_set *match) 1959 { 1960 struct ip_fw *rule; 1961 1962 for (rule = layer3_chain; rule; rule = rule->next) { 1963 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 1964 1965 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 1966 continue; 1967 if (match == NULL || cmd->pipe_ptr == match) 1968 cmd->pipe_ptr = NULL; 1969 } 1970 } 1971 1972 /* 1973 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 1974 * possibly create a rule number and add the rule to the list. 1975 * Update the rule_number in the input struct so the caller knows it as well. 1976 */ 1977 static int 1978 add_rule(struct ip_fw **head, struct ip_fw *input_rule) 1979 { 1980 struct ip_fw *rule, *f, *prev; 1981 int s; 1982 int l = RULESIZE(input_rule); 1983 1984 if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 1985 return (EINVAL); 1986 1987 rule = malloc(l, M_IPFW, M_WAITOK | M_ZERO); 1988 if (rule == NULL) 1989 return (ENOSPC); 1990 1991 bcopy(input_rule, rule, l); 1992 1993 rule->next = NULL; 1994 rule->next_rule = NULL; 1995 1996 rule->pcnt = 0; 1997 rule->bcnt = 0; 1998 rule->timestamp = 0; 1999 2000 s = splimp(); 2001 2002 if (*head == NULL) { /* default rule */ 2003 *head = rule; 2004 goto done; 2005 } 2006 2007 /* 2008 * If rulenum is 0, find highest numbered rule before the 2009 * default rule, and add autoinc_step 2010 */ 2011 if (autoinc_step < 1) 2012 autoinc_step = 1; 2013 else if (autoinc_step > 1000) 2014 autoinc_step = 1000; 2015 if (rule->rulenum == 0) { 2016 /* 2017 * locate the highest numbered rule before default 2018 */ 2019 for (f = *head; f; f = f->next) { 2020 if (f->rulenum == IPFW_DEFAULT_RULE) 2021 break; 2022 rule->rulenum = f->rulenum; 2023 } 2024 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2025 rule->rulenum += autoinc_step; 2026 input_rule->rulenum = rule->rulenum; 2027 } 2028 2029 /* 2030 * Now insert the new rule in the right place in the sorted list. 2031 */ 2032 for (prev = NULL, f = *head; f; prev = f, f = f->next) { 2033 if (f->rulenum > rule->rulenum) { /* found the location */ 2034 if (prev) { 2035 rule->next = f; 2036 prev->next = rule; 2037 } else { /* head insert */ 2038 rule->next = *head; 2039 *head = rule; 2040 } 2041 break; 2042 } 2043 } 2044 flush_rule_ptrs(); 2045 done: 2046 static_count++; 2047 static_len += l; 2048 splx(s); 2049 DEB(printf("++ installed rule %d, static count now %d\n", 2050 rule->rulenum, static_count);) 2051 return (0); 2052 } 2053 2054 /** 2055 * Free storage associated with a static rule (including derived 2056 * dynamic rules). 2057 * The caller is in charge of clearing rule pointers to avoid 2058 * dangling pointers. 2059 * @return a pointer to the next entry. 2060 * Arguments are not checked, so they better be correct. 2061 * Must be called at splimp(). 2062 */ 2063 static struct ip_fw * 2064 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) 2065 { 2066 struct ip_fw *n; 2067 int l = RULESIZE(rule); 2068 2069 n = rule->next; 2070 remove_dyn_rule(rule, NULL /* force removal */); 2071 if (prev == NULL) 2072 *head = n; 2073 else 2074 prev->next = n; 2075 static_count--; 2076 static_len -= l; 2077 2078 if (DUMMYNET_LOADED) 2079 ip_dn_ruledel_ptr(rule); 2080 free(rule, M_IPFW); 2081 return n; 2082 } 2083 2084 /* 2085 * Deletes all rules from a chain (including the default rule 2086 * if the second argument is set). 2087 * Must be called at splimp(). 2088 */ 2089 static void 2090 free_chain(struct ip_fw **chain, int kill_default) 2091 { 2092 struct ip_fw *rule; 2093 2094 flush_rule_ptrs(); /* more efficient to do outside the loop */ 2095 2096 while ( (rule = *chain) != NULL && 2097 (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) 2098 delete_rule(chain, NULL, rule); 2099 } 2100 2101 /** 2102 * Remove all rules with given number, and also do set manipulation. 2103 * 2104 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2105 * the next 8 bits are the new set, the top 8 bits are the command: 2106 * 2107 * 0 delete rules with given number 2108 * 1 delete rules with given set number 2109 * 2 move rules with given number to new set 2110 * 3 move rules with given set number to new set 2111 * 4 swap sets with given numbers 2112 */ 2113 static int 2114 del_entry(struct ip_fw **chain, u_int32_t arg) 2115 { 2116 struct ip_fw *prev, *rule; 2117 int s; 2118 u_int16_t rulenum; 2119 u_int8_t cmd, new_set; 2120 2121 rulenum = arg & 0xffff; 2122 cmd = (arg >> 24) & 0xff; 2123 new_set = (arg >> 16) & 0xff; 2124 2125 if (cmd > 4) 2126 return EINVAL; 2127 if (new_set > 30) 2128 return EINVAL; 2129 if (cmd == 0 || cmd == 2) { 2130 if (rulenum == IPFW_DEFAULT_RULE) 2131 return EINVAL; 2132 } else { 2133 if (rulenum > 30) 2134 return EINVAL; 2135 } 2136 2137 switch (cmd) { 2138 case 0: /* delete rules with given number */ 2139 /* 2140 * locate first rule to delete 2141 */ 2142 for (prev = NULL, rule = *chain; 2143 rule && rule->rulenum < rulenum; 2144 prev = rule, rule = rule->next) 2145 ; 2146 if (rule->rulenum != rulenum) 2147 return EINVAL; 2148 2149 s = splimp(); /* no access to rules while removing */ 2150 /* 2151 * flush pointers outside the loop, then delete all matching 2152 * rules. prev remains the same throughout the cycle. 2153 */ 2154 flush_rule_ptrs(); 2155 while (rule && rule->rulenum == rulenum) 2156 rule = delete_rule(chain, prev, rule); 2157 splx(s); 2158 break; 2159 2160 case 1: /* delete all rules with given set number */ 2161 s = splimp(); 2162 flush_rule_ptrs(); 2163 for (prev = NULL, rule = *chain; rule ; ) 2164 if (rule->set == rulenum) 2165 rule = delete_rule(chain, prev, rule); 2166 else { 2167 prev = rule; 2168 rule = rule->next; 2169 } 2170 splx(s); 2171 break; 2172 2173 case 2: /* move rules with given number to new set */ 2174 s = splimp(); 2175 for (rule = *chain; rule ; rule = rule->next) 2176 if (rule->rulenum == rulenum) 2177 rule->set = new_set; 2178 splx(s); 2179 break; 2180 2181 case 3: /* move rules with given set number to new set */ 2182 s = splimp(); 2183 for (rule = *chain; rule ; rule = rule->next) 2184 if (rule->set == rulenum) 2185 rule->set = new_set; 2186 splx(s); 2187 break; 2188 2189 case 4: /* swap two sets */ 2190 s = splimp(); 2191 for (rule = *chain; rule ; rule = rule->next) 2192 if (rule->set == rulenum) 2193 rule->set = new_set; 2194 else if (rule->set == new_set) 2195 rule->set = rulenum; 2196 splx(s); 2197 break; 2198 } 2199 return 0; 2200 } 2201 2202 /* 2203 * Clear counters for a specific rule. 2204 */ 2205 static void 2206 clear_counters(struct ip_fw *rule, int log_only) 2207 { 2208 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2209 2210 if (log_only == 0) { 2211 rule->bcnt = rule->pcnt = 0; 2212 rule->timestamp = 0; 2213 } 2214 if (l->o.opcode == O_LOG) 2215 l->log_left = l->max_log; 2216 } 2217 2218 /** 2219 * Reset some or all counters on firewall rules. 2220 * @arg frwl is null to clear all entries, or contains a specific 2221 * rule number. 2222 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2223 */ 2224 static int 2225 zero_entry(int rulenum, int log_only) 2226 { 2227 struct ip_fw *rule; 2228 int s; 2229 char *msg; 2230 2231 if (rulenum == 0) { 2232 s = splimp(); 2233 norule_counter = 0; 2234 for (rule = layer3_chain; rule; rule = rule->next) 2235 clear_counters(rule, log_only); 2236 splx(s); 2237 msg = log_only ? "ipfw: All logging counts reset.\n" : 2238 "ipfw: Accounting cleared.\n"; 2239 } else { 2240 int cleared = 0; 2241 /* 2242 * We can have multiple rules with the same number, so we 2243 * need to clear them all. 2244 */ 2245 for (rule = layer3_chain; rule; rule = rule->next) 2246 if (rule->rulenum == rulenum) { 2247 s = splimp(); 2248 while (rule && rule->rulenum == rulenum) { 2249 clear_counters(rule, log_only); 2250 rule = rule->next; 2251 } 2252 splx(s); 2253 cleared = 1; 2254 break; 2255 } 2256 if (!cleared) /* we did not find any matching rules */ 2257 return (EINVAL); 2258 msg = log_only ? "ipfw: Entry %d logging count reset.\n" : 2259 "ipfw: Entry %d cleared.\n"; 2260 } 2261 if (fw_verbose) 2262 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); 2263 return (0); 2264 } 2265 2266 /* 2267 * Check validity of the structure before insert. 2268 * Fortunately rules are simple, so this mostly need to check rule sizes. 2269 */ 2270 static int 2271 check_ipfw_struct(struct ip_fw *rule, int size) 2272 { 2273 int l, cmdlen = 0; 2274 int have_action=0; 2275 ipfw_insn *cmd; 2276 2277 if (size < sizeof(*rule)) { 2278 printf("ipfw: rule too short\n"); 2279 return (EINVAL); 2280 } 2281 /* first, check for valid size */ 2282 l = RULESIZE(rule); 2283 if (l != size) { 2284 printf("ipfw: size mismatch (have %d want %d)\n", size, l); 2285 return (EINVAL); 2286 } 2287 /* 2288 * Now go for the individual checks. Very simple ones, basically only 2289 * instruction sizes. 2290 */ 2291 for (l = rule->cmd_len, cmd = rule->cmd ; 2292 l > 0 ; l -= cmdlen, cmd += cmdlen) { 2293 cmdlen = F_LEN(cmd); 2294 if (cmdlen > l) { 2295 printf("ipfw: opcode %d size truncated\n", 2296 cmd->opcode); 2297 return EINVAL; 2298 } 2299 DEB(printf("ipfw: opcode %d\n", cmd->opcode);) 2300 switch (cmd->opcode) { 2301 case O_NOP: 2302 case O_PROBE_STATE: 2303 case O_KEEP_STATE: 2304 case O_PROTO: 2305 case O_IP_SRC_ME: 2306 case O_IP_DST_ME: 2307 case O_LAYER2: 2308 case O_IN: 2309 case O_FRAG: 2310 case O_IPOPT: 2311 case O_IPLEN: 2312 case O_IPID: 2313 case O_IPTOS: 2314 case O_IPPRECEDENCE: 2315 case O_IPTTL: 2316 case O_IPVER: 2317 case O_TCPWIN: 2318 case O_TCPFLAGS: 2319 case O_TCPOPTS: 2320 case O_ESTAB: 2321 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2322 goto bad_size; 2323 break; 2324 2325 case O_UID: 2326 case O_GID: 2327 case O_IP_SRC: 2328 case O_IP_DST: 2329 case O_TCPSEQ: 2330 case O_TCPACK: 2331 case O_PROB: 2332 case O_ICMPTYPE: 2333 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) 2334 goto bad_size; 2335 break; 2336 2337 case O_LIMIT: 2338 if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) 2339 goto bad_size; 2340 break; 2341 2342 case O_LOG: 2343 if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) 2344 goto bad_size; 2345 2346 ((ipfw_insn_log *)cmd)->log_left = 2347 ((ipfw_insn_log *)cmd)->max_log; 2348 2349 break; 2350 2351 case O_IP_SRC_MASK: 2352 case O_IP_DST_MASK: 2353 if (cmdlen != F_INSN_SIZE(ipfw_insn_ip)) 2354 goto bad_size; 2355 if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) { 2356 printf("ipfw: opcode %d, useless rule\n", 2357 cmd->opcode); 2358 return EINVAL; 2359 } 2360 break; 2361 2362 case O_IP_SRC_SET: 2363 case O_IP_DST_SET: 2364 if (cmd->arg1 == 0 || cmd->arg1 > 256) { 2365 printf("ipfw: invalid set size %d\n", 2366 cmd->arg1); 2367 return EINVAL; 2368 } 2369 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + 2370 (cmd->arg1+31)/32 ) 2371 goto bad_size; 2372 break; 2373 2374 case O_MACADDR2: 2375 if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) 2376 goto bad_size; 2377 break; 2378 2379 case O_MAC_TYPE: 2380 case O_IP_SRCPORT: 2381 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ 2382 if (cmdlen < 2 || cmdlen > 31) 2383 goto bad_size; 2384 break; 2385 2386 case O_RECV: 2387 case O_XMIT: 2388 case O_VIA: 2389 if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) 2390 goto bad_size; 2391 break; 2392 2393 case O_PIPE: 2394 case O_QUEUE: 2395 if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) 2396 goto bad_size; 2397 goto check_action; 2398 2399 case O_FORWARD_IP: 2400 if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) 2401 goto bad_size; 2402 goto check_action; 2403 2404 case O_FORWARD_MAC: /* XXX not implemented yet */ 2405 case O_CHECK_STATE: 2406 case O_COUNT: 2407 case O_ACCEPT: 2408 case O_DENY: 2409 case O_REJECT: 2410 case O_SKIPTO: 2411 case O_DIVERT: 2412 case O_TEE: 2413 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2414 goto bad_size; 2415 check_action: 2416 if (have_action) { 2417 printf("ipfw: opcode %d, multiple actions" 2418 " not allowed\n", 2419 cmd->opcode); 2420 return EINVAL; 2421 } 2422 have_action = 1; 2423 if (l != cmdlen) { 2424 printf("ipfw: opcode %d, action must be" 2425 " last opcode\n", 2426 cmd->opcode); 2427 return EINVAL; 2428 } 2429 break; 2430 default: 2431 printf("ipfw: opcode %d, unknown opcode\n", 2432 cmd->opcode); 2433 return EINVAL; 2434 } 2435 } 2436 if (have_action == 0) { 2437 printf("ipfw: missing action\n"); 2438 return EINVAL; 2439 } 2440 return 0; 2441 2442 bad_size: 2443 printf("ipfw: opcode %d size %d wrong\n", 2444 cmd->opcode, cmdlen); 2445 return EINVAL; 2446 } 2447 2448 2449 /** 2450 * {set|get}sockopt parser. 2451 */ 2452 static int 2453 ipfw_ctl(struct sockopt *sopt) 2454 { 2455 int error, s, rulenum; 2456 size_t size; 2457 struct ip_fw *bp , *buf, *rule; 2458 2459 static u_int32_t rule_buf[255]; /* we copy the data here */ 2460 2461 /* 2462 * Disallow modifications in really-really secure mode, but still allow 2463 * the logging counters to be reset. 2464 */ 2465 if (sopt->sopt_name == IP_FW_ADD || 2466 (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { 2467 #if defined(__FreeBSD__) && __FreeBSD_version >= 500034 2468 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); 2469 if (error) 2470 return (error); 2471 #else /* FreeBSD 4.x */ 2472 if (securelevel >= 3) 2473 return (EPERM); 2474 #endif 2475 } 2476 2477 error = 0; 2478 2479 switch (sopt->sopt_name) { 2480 case IP_FW_GET: 2481 /* 2482 * pass up a copy of the current rules. Static rules 2483 * come first (the last of which has number IPFW_DEFAULT_RULE), 2484 * followed by a possibly empty list of dynamic rule. 2485 * The last dynamic rule has NULL in the "next" field. 2486 */ 2487 s = splimp(); 2488 size = static_len; /* size of static rules */ 2489 if (ipfw_dyn_v) /* add size of dyn.rules */ 2490 size += (dyn_count * sizeof(ipfw_dyn_rule)); 2491 2492 /* 2493 * XXX todo: if the user passes a short length just to know 2494 * how much room is needed, do not bother filling up the 2495 * buffer, just jump to the sooptcopyout. 2496 */ 2497 buf = malloc(size, M_TEMP, M_WAITOK); 2498 2499 bp = buf; 2500 for (rule = layer3_chain; rule ; rule = rule->next) { 2501 int i = RULESIZE(rule); 2502 bcopy(rule, bp, i); 2503 /* 2504 * abuse 'next_rule' to store the set_disable word 2505 */ 2506 (u_int32_t)(((struct ip_fw *)bp)->next_rule) = 2507 set_disable; 2508 bp = (struct ip_fw *)((char *)bp + i); 2509 } 2510 if (ipfw_dyn_v) { 2511 int i; 2512 ipfw_dyn_rule *p, *dst, *last = NULL; 2513 2514 dst = (ipfw_dyn_rule *)bp; 2515 for (i = 0 ; i < curr_dyn_buckets ; i++ ) 2516 for ( p = ipfw_dyn_v[i] ; p != NULL ; 2517 p = p->next, dst++ ) { 2518 bcopy(p, dst, sizeof *p); 2519 (int)dst->rule = p->rule->rulenum ; 2520 /* 2521 * store a non-null value in "next". 2522 * The userland code will interpret a 2523 * NULL here as a marker 2524 * for the last dynamic rule. 2525 */ 2526 dst->next = dst ; 2527 last = dst ; 2528 dst->expire = 2529 TIME_LEQ(dst->expire, time_second) ? 2530 0 : dst->expire - time_second ; 2531 } 2532 if (last != NULL) /* mark last dynamic rule */ 2533 last->next = NULL; 2534 } 2535 splx(s); 2536 2537 error = sooptcopyout(sopt, buf, size); 2538 free(buf, M_TEMP); 2539 break; 2540 2541 case IP_FW_FLUSH: 2542 /* 2543 * Normally we cannot release the lock on each iteration. 2544 * We could do it here only because we start from the head all 2545 * the times so there is no risk of missing some entries. 2546 * On the other hand, the risk is that we end up with 2547 * a very inconsistent ruleset, so better keep the lock 2548 * around the whole cycle. 2549 * 2550 * XXX this code can be improved by resetting the head of 2551 * the list to point to the default rule, and then freeing 2552 * the old list without the need for a lock. 2553 */ 2554 2555 s = splimp(); 2556 free_chain(&layer3_chain, 0 /* keep default rule */); 2557 splx(s); 2558 break; 2559 2560 case IP_FW_ADD: 2561 rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ 2562 error = sooptcopyin(sopt, rule, sizeof(rule_buf), 2563 sizeof(struct ip_fw) ); 2564 size = sopt->sopt_valsize; 2565 if (error || (error = check_ipfw_struct(rule, size))) 2566 break; 2567 2568 error = add_rule(&layer3_chain, rule); 2569 size = RULESIZE(rule); 2570 if (!error && sopt->sopt_dir == SOPT_GET) 2571 error = sooptcopyout(sopt, rule, size); 2572 break; 2573 2574 case IP_FW_DEL: 2575 /* 2576 * IP_FW_DEL is used for deleting single rules or sets, 2577 * and (ab)used to atomically manipulate sets. Argument size 2578 * is used to distinguish between the two: 2579 * sizeof(u_int32_t) 2580 * delete single rule or set of rules, 2581 * or reassign rules (or sets) to a different set. 2582 * 2*sizeof(u_int32_t) 2583 * atomic disable/enable sets. 2584 * first u_int32_t contains sets to be disabled, 2585 * second u_int32_t contains sets to be enabled. 2586 */ 2587 error = sooptcopyin(sopt, rule_buf, 2588 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2589 if (error) 2590 break; 2591 size = sopt->sopt_valsize; 2592 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2593 error = del_entry(&layer3_chain, rule_buf[0]); 2594 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2595 set_disable = 2596 (set_disable | rule_buf[0]) & ~rule_buf[1] & 2597 ~(1<<31); /* set 31 always enabled */ 2598 else 2599 error = EINVAL; 2600 break; 2601 2602 case IP_FW_ZERO: 2603 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2604 rulenum=0; 2605 2606 if (sopt->sopt_val != 0) { 2607 error = sooptcopyin(sopt, &rulenum, 2608 sizeof(int), sizeof(int)); 2609 if (error) 2610 break; 2611 } 2612 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); 2613 break; 2614 2615 default: 2616 printf("ipfw_ctl invalid option %d\n", sopt->sopt_name); 2617 error = EINVAL; 2618 } 2619 2620 return (error); 2621 } 2622 2623 /** 2624 * dummynet needs a reference to the default rule, because rules can be 2625 * deleted while packets hold a reference to them. When this happens, 2626 * dummynet changes the reference to the default rule (it could well be a 2627 * NULL pointer, but this way we do not need to check for the special 2628 * case, plus here he have info on the default behaviour). 2629 */ 2630 struct ip_fw *ip_fw_default_rule; 2631 2632 /* 2633 * This procedure is only used to handle keepalives. It is invoked 2634 * every dyn_keepalive_period 2635 */ 2636 static void 2637 ipfw_tick(void * __unused unused) 2638 { 2639 int i; 2640 int s; 2641 ipfw_dyn_rule *q; 2642 2643 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2644 goto done; 2645 2646 s = splimp(); 2647 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2648 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2649 if (q->dyn_type == O_LIMIT_PARENT) 2650 continue; 2651 if (q->id.proto != IPPROTO_TCP) 2652 continue; 2653 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2654 continue; 2655 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2656 q->expire)) 2657 continue; /* too early */ 2658 if (TIME_LEQ(q->expire, time_second)) 2659 continue; /* too late, rule expired */ 2660 2661 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2662 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2663 } 2664 } 2665 splx(s); 2666 done: 2667 callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz, 2668 ipfw_tick, NULL); 2669 } 2670 2671 static void 2672 ipfw_init(void) 2673 { 2674 struct ip_fw default_rule; 2675 2676 ip_fw_chk_ptr = ipfw_chk; 2677 ip_fw_ctl_ptr = ipfw_ctl; 2678 layer3_chain = NULL; 2679 2680 bzero(&default_rule, sizeof default_rule); 2681 2682 default_rule.act_ofs = 0; 2683 default_rule.rulenum = IPFW_DEFAULT_RULE; 2684 default_rule.cmd_len = 1; 2685 default_rule.set = 31; 2686 2687 default_rule.cmd[0].len = 1; 2688 default_rule.cmd[0].opcode = 2689 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2690 1 ? O_ACCEPT : 2691 #endif 2692 O_DENY; 2693 2694 add_rule(&layer3_chain, &default_rule); 2695 2696 ip_fw_default_rule = layer3_chain; 2697 printf("ipfw2 initialized, divert %s, " 2698 "rule-based forwarding enabled, default to %s, logging ", 2699 #ifdef IPDIVERT 2700 "enabled", 2701 #else 2702 "disabled", 2703 #endif 2704 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2705 2706 #ifdef IPFIREWALL_VERBOSE 2707 fw_verbose = 1; 2708 #endif 2709 #ifdef IPFIREWALL_VERBOSE_LIMIT 2710 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2711 #endif 2712 if (fw_verbose == 0) 2713 printf("disabled\n"); 2714 else if (verbose_limit == 0) 2715 printf("unlimited\n"); 2716 else 2717 printf("limited to %d packets/entry by default\n", 2718 verbose_limit); 2719 callout_init(&ipfw_timeout_h); 2720 callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL); 2721 } 2722 2723 static int 2724 ipfw_modevent(module_t mod, int type, void *unused) 2725 { 2726 int s; 2727 int err = 0; 2728 2729 switch (type) { 2730 case MOD_LOAD: 2731 s = splimp(); 2732 if (IPFW_LOADED) { 2733 splx(s); 2734 printf("IP firewall already loaded\n"); 2735 err = EEXIST; 2736 } else { 2737 ipfw_init(); 2738 splx(s); 2739 } 2740 break; 2741 2742 case MOD_UNLOAD: 2743 #if !defined(KLD_MODULE) 2744 printf("ipfw statically compiled, cannot unload\n"); 2745 err = EBUSY; 2746 #else 2747 s = splimp(); 2748 callout_stop(&ipfw_timeout_h); 2749 ip_fw_chk_ptr = NULL; 2750 ip_fw_ctl_ptr = NULL; 2751 free_chain(&layer3_chain, 1 /* kill default rule */); 2752 splx(s); 2753 printf("IP firewall unloaded\n"); 2754 #endif 2755 break; 2756 default: 2757 break; 2758 } 2759 return err; 2760 } 2761 2762 static moduledata_t ipfwmod = { 2763 "ipfw", 2764 ipfw_modevent, 2765 0 2766 }; 2767 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); 2768 MODULE_VERSION(ipfw, 1); 2769 #endif /* IPFW2 */ 2770