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 1.5 2004/01/06 03:17:26 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 <net/if.h> 59 #include <net/route.h> 60 #include <netinet/in.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/in_var.h> 63 #include <netinet/in_pcb.h> 64 #include <netinet/ip.h> 65 #include <netinet/ip_var.h> 66 #include <netinet/ip_icmp.h> 67 #include "ip_fw.h" 68 #include <net/dummynet/ip_dummynet.h> 69 #include <netinet/tcp.h> 70 #include <netinet/tcp_timer.h> 71 #include <netinet/tcp_var.h> 72 #include <netinet/tcpip.h> 73 #include <netinet/udp.h> 74 #include <netinet/udp_var.h> 75 76 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */ 77 78 #include <machine/in_cksum.h> /* XXX for in_cksum */ 79 80 /* 81 * XXX This one should go in sys/mbuf.h. It is used to avoid that 82 * a firewall-generated packet loops forever through the firewall. 83 */ 84 #ifndef M_SKIP_FIREWALL 85 #define M_SKIP_FIREWALL 0x4000 86 #endif 87 88 /* 89 * set_disable contains one bit per set value (0..31). 90 * If the bit is set, all rules with the corresponding set 91 * are disabled. Set 31 is reserved for the default rule 92 * and CANNOT be disabled. 93 */ 94 static u_int32_t set_disable; 95 96 static int fw_verbose; 97 static int verbose_limit; 98 99 static struct callout_handle ipfw_timeout_h; 100 #define IPFW_DEFAULT_RULE 65535 101 102 /* 103 * list of rules for layer 3 104 */ 105 static struct ip_fw *layer3_chain; 106 107 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 108 109 static int fw_debug = 1; 110 static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 111 112 #ifdef SYSCTL_NODE 113 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 114 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, 115 &fw_enable, 0, "Enable ipfw"); 116 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 117 &autoinc_step, 0, "Rule number autincrement step"); 118 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, 119 &fw_one_pass, 0, 120 "Only do a single pass through ipfw when using dummynet(4)"); 121 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 122 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 123 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, 124 &fw_verbose, 0, "Log matches to ipfw rules"); 125 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 126 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 127 128 /* 129 * Description of dynamic rules. 130 * 131 * Dynamic rules are stored in lists accessed through a hash table 132 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 133 * be modified through the sysctl variable dyn_buckets which is 134 * updated when the table becomes empty. 135 * 136 * XXX currently there is only one list, ipfw_dyn. 137 * 138 * When a packet is received, its address fields are first masked 139 * with the mask defined for the rule, then hashed, then matched 140 * against the entries in the corresponding list. 141 * Dynamic rules can be used for different purposes: 142 * + stateful rules; 143 * + enforcing limits on the number of sessions; 144 * + in-kernel NAT (not implemented yet) 145 * 146 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 147 * measured in seconds and depending on the flags. 148 * 149 * The total number of dynamic rules is stored in dyn_count. 150 * The max number of dynamic rules is dyn_max. When we reach 151 * the maximum number of rules we do not create anymore. This is 152 * done to avoid consuming too much memory, but also too much 153 * time when searching on each packet (ideally, we should try instead 154 * to put a limit on the length of the list on each bucket...). 155 * 156 * Each dynamic rule holds a pointer to the parent ipfw rule so 157 * we know what action to perform. Dynamic rules are removed when 158 * the parent rule is deleted. XXX we should make them survive. 159 * 160 * There are some limitations with dynamic rules -- we do not 161 * obey the 'randomized match', and we do not do multiple 162 * passes through the firewall. XXX check the latter!!! 163 */ 164 static ipfw_dyn_rule **ipfw_dyn_v = NULL; 165 static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 166 static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 167 168 /* 169 * Timeouts for various events in handing dynamic rules. 170 */ 171 static u_int32_t dyn_ack_lifetime = 300; 172 static u_int32_t dyn_syn_lifetime = 20; 173 static u_int32_t dyn_fin_lifetime = 1; 174 static u_int32_t dyn_rst_lifetime = 1; 175 static u_int32_t dyn_udp_lifetime = 10; 176 static u_int32_t dyn_short_lifetime = 5; 177 178 /* 179 * Keepalives are sent if dyn_keepalive is set. They are sent every 180 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 181 * seconds of lifetime of a rule. 182 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 183 * than dyn_keepalive_period. 184 */ 185 186 static u_int32_t dyn_keepalive_interval = 20; 187 static u_int32_t dyn_keepalive_period = 5; 188 static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 189 190 static u_int32_t static_count; /* # of static rules */ 191 static u_int32_t static_len; /* size in bytes of static rules */ 192 static u_int32_t dyn_count; /* # of dynamic rules */ 193 static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 194 195 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 196 &dyn_buckets, 0, "Number of dyn. buckets"); 197 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 198 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 199 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 200 &dyn_count, 0, "Number of dyn. rules"); 201 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 202 &dyn_max, 0, "Max number of dyn. rules"); 203 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 204 &static_count, 0, "Number of static rules"); 205 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 206 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 207 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 208 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 209 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 210 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 211 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 212 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 213 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 214 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 215 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 216 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 217 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 218 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 219 220 #endif /* SYSCTL_NODE */ 221 222 223 static ip_fw_chk_t ipfw_chk; 224 225 ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 226 227 /* 228 * This macro maps an ip pointer into a layer3 header pointer of type T 229 */ 230 #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 231 232 static __inline int 233 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 234 { 235 int type = L3HDR(struct icmp,ip)->icmp_type; 236 237 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 238 } 239 240 #define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 241 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 242 243 static int 244 is_icmp_query(struct ip *ip) 245 { 246 int type = L3HDR(struct icmp, ip)->icmp_type; 247 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 248 } 249 #undef TT 250 251 /* 252 * The following checks use two arrays of 8 or 16 bits to store the 253 * bits that we want set or clear, respectively. They are in the 254 * low and high half of cmd->arg1 or cmd->d[0]. 255 * 256 * We scan options and store the bits we find set. We succeed if 257 * 258 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 259 * 260 * The code is sometimes optimized not to store additional variables. 261 */ 262 263 static int 264 flags_match(ipfw_insn *cmd, u_int8_t bits) 265 { 266 u_char want_clear; 267 bits = ~bits; 268 269 if ( ((cmd->arg1 & 0xff) & bits) != 0) 270 return 0; /* some bits we want set were clear */ 271 want_clear = (cmd->arg1 >> 8) & 0xff; 272 if ( (want_clear & bits) != want_clear) 273 return 0; /* some bits we want clear were set */ 274 return 1; 275 } 276 277 static int 278 ipopts_match(struct ip *ip, ipfw_insn *cmd) 279 { 280 int optlen, bits = 0; 281 u_char *cp = (u_char *)(ip + 1); 282 int x = (ip->ip_hl << 2) - sizeof (struct ip); 283 284 for (; x > 0; x -= optlen, cp += optlen) { 285 int opt = cp[IPOPT_OPTVAL]; 286 287 if (opt == IPOPT_EOL) 288 break; 289 if (opt == IPOPT_NOP) 290 optlen = 1; 291 else { 292 optlen = cp[IPOPT_OLEN]; 293 if (optlen <= 0 || optlen > x) 294 return 0; /* invalid or truncated */ 295 } 296 switch (opt) { 297 298 default: 299 break; 300 301 case IPOPT_LSRR: 302 bits |= IP_FW_IPOPT_LSRR; 303 break; 304 305 case IPOPT_SSRR: 306 bits |= IP_FW_IPOPT_SSRR; 307 break; 308 309 case IPOPT_RR: 310 bits |= IP_FW_IPOPT_RR; 311 break; 312 313 case IPOPT_TS: 314 bits |= IP_FW_IPOPT_TS; 315 break; 316 } 317 } 318 return (flags_match(cmd, bits)); 319 } 320 321 static int 322 tcpopts_match(struct ip *ip, ipfw_insn *cmd) 323 { 324 int optlen, bits = 0; 325 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 326 u_char *cp = (u_char *)(tcp + 1); 327 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 328 329 for (; x > 0; x -= optlen, cp += optlen) { 330 int opt = cp[0]; 331 if (opt == TCPOPT_EOL) 332 break; 333 if (opt == TCPOPT_NOP) 334 optlen = 1; 335 else { 336 optlen = cp[1]; 337 if (optlen <= 0) 338 break; 339 } 340 341 switch (opt) { 342 343 default: 344 break; 345 346 case TCPOPT_MAXSEG: 347 bits |= IP_FW_TCPOPT_MSS; 348 break; 349 350 case TCPOPT_WINDOW: 351 bits |= IP_FW_TCPOPT_WINDOW; 352 break; 353 354 case TCPOPT_SACK_PERMITTED: 355 case TCPOPT_SACK: 356 bits |= IP_FW_TCPOPT_SACK; 357 break; 358 359 case TCPOPT_TIMESTAMP: 360 bits |= IP_FW_TCPOPT_TS; 361 break; 362 363 case TCPOPT_CC: 364 case TCPOPT_CCNEW: 365 case TCPOPT_CCECHO: 366 bits |= IP_FW_TCPOPT_CC; 367 break; 368 } 369 } 370 return (flags_match(cmd, bits)); 371 } 372 373 static int 374 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 375 { 376 if (ifp == NULL) /* no iface with this packet, match fails */ 377 return 0; 378 /* Check by name or by IP address */ 379 if (cmd->name[0] != '\0') { /* match by name */ 380 /* Check name */ 381 if (cmd->p.glob) { 382 if (fnmatch(cmd->name, ifp->if_xname, 0) == 0) 383 return(1); 384 } else { 385 if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) 386 return(1); 387 } 388 } else { 389 struct ifaddr *ia; 390 391 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 392 if (ia->ifa_addr == NULL) 393 continue; 394 if (ia->ifa_addr->sa_family != AF_INET) 395 continue; 396 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 397 (ia->ifa_addr))->sin_addr.s_addr) 398 return(1); /* match */ 399 } 400 } 401 return(0); /* no match, fail ... */ 402 } 403 404 static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 405 406 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 407 #define SNP(buf) buf, sizeof(buf) 408 409 /* 410 * We enter here when we have a rule with O_LOG. 411 * XXX this function alone takes about 2Kbytes of code! 412 */ 413 static void 414 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 415 struct mbuf *m, struct ifnet *oif) 416 { 417 char *action; 418 int limit_reached = 0; 419 char action2[40], proto[48], fragment[28]; 420 421 fragment[0] = '\0'; 422 proto[0] = '\0'; 423 424 if (f == NULL) { /* bogus pkt */ 425 if (verbose_limit != 0 && norule_counter >= verbose_limit) 426 return; 427 norule_counter++; 428 if (norule_counter == verbose_limit) 429 limit_reached = verbose_limit; 430 action = "Refuse"; 431 } else { /* O_LOG is the first action, find the real one */ 432 ipfw_insn *cmd = ACTION_PTR(f); 433 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 434 435 if (l->max_log != 0 && l->log_left == 0) 436 return; 437 l->log_left--; 438 if (l->log_left == 0) 439 limit_reached = l->max_log; 440 cmd += F_LEN(cmd); /* point to first action */ 441 if (cmd->opcode == O_PROB) 442 cmd += F_LEN(cmd); 443 444 action = action2; 445 switch (cmd->opcode) { 446 case O_DENY: 447 action = "Deny"; 448 break; 449 450 case O_REJECT: 451 if (cmd->arg1==ICMP_REJECT_RST) 452 action = "Reset"; 453 else if (cmd->arg1==ICMP_UNREACH_HOST) 454 action = "Reject"; 455 else 456 snprintf(SNPARGS(action2, 0), "Unreach %d", 457 cmd->arg1); 458 break; 459 460 case O_ACCEPT: 461 action = "Accept"; 462 break; 463 case O_COUNT: 464 action = "Count"; 465 break; 466 case O_DIVERT: 467 snprintf(SNPARGS(action2, 0), "Divert %d", 468 cmd->arg1); 469 break; 470 case O_TEE: 471 snprintf(SNPARGS(action2, 0), "Tee %d", 472 cmd->arg1); 473 break; 474 case O_SKIPTO: 475 snprintf(SNPARGS(action2, 0), "SkipTo %d", 476 cmd->arg1); 477 break; 478 case O_PIPE: 479 snprintf(SNPARGS(action2, 0), "Pipe %d", 480 cmd->arg1); 481 break; 482 case O_QUEUE: 483 snprintf(SNPARGS(action2, 0), "Queue %d", 484 cmd->arg1); 485 break; 486 case O_FORWARD_IP: { 487 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 488 int len; 489 490 len = snprintf(SNPARGS(action2, 0), "Forward to %s", 491 inet_ntoa(sa->sa.sin_addr)); 492 if (sa->sa.sin_port) 493 snprintf(SNPARGS(action2, len), ":%d", 494 sa->sa.sin_port); 495 } 496 break; 497 default: 498 action = "UNKNOWN"; 499 break; 500 } 501 } 502 503 if (hlen == 0) { /* non-ip */ 504 snprintf(SNPARGS(proto, 0), "MAC"); 505 } else { 506 struct ip *ip = mtod(m, struct ip *); 507 /* these three are all aliases to the same thing */ 508 struct icmp *const icmp = L3HDR(struct icmp, ip); 509 struct tcphdr *const tcp = (struct tcphdr *)icmp; 510 struct udphdr *const udp = (struct udphdr *)icmp; 511 512 int ip_off, offset, ip_len; 513 514 int len; 515 516 if (eh != NULL) { /* layer 2 packets are as on the wire */ 517 ip_off = ntohs(ip->ip_off); 518 ip_len = ntohs(ip->ip_len); 519 } else { 520 ip_off = ip->ip_off; 521 ip_len = ip->ip_len; 522 } 523 offset = ip_off & IP_OFFMASK; 524 switch (ip->ip_p) { 525 case IPPROTO_TCP: 526 len = snprintf(SNPARGS(proto, 0), "TCP %s", 527 inet_ntoa(ip->ip_src)); 528 if (offset == 0) 529 snprintf(SNPARGS(proto, len), ":%d %s:%d", 530 ntohs(tcp->th_sport), 531 inet_ntoa(ip->ip_dst), 532 ntohs(tcp->th_dport)); 533 else 534 snprintf(SNPARGS(proto, len), " %s", 535 inet_ntoa(ip->ip_dst)); 536 break; 537 538 case IPPROTO_UDP: 539 len = snprintf(SNPARGS(proto, 0), "UDP %s", 540 inet_ntoa(ip->ip_src)); 541 if (offset == 0) 542 snprintf(SNPARGS(proto, len), ":%d %s:%d", 543 ntohs(udp->uh_sport), 544 inet_ntoa(ip->ip_dst), 545 ntohs(udp->uh_dport)); 546 else 547 snprintf(SNPARGS(proto, len), " %s", 548 inet_ntoa(ip->ip_dst)); 549 break; 550 551 case IPPROTO_ICMP: 552 if (offset == 0) 553 len = snprintf(SNPARGS(proto, 0), 554 "ICMP:%u.%u ", 555 icmp->icmp_type, icmp->icmp_code); 556 else 557 len = snprintf(SNPARGS(proto, 0), "ICMP "); 558 len += snprintf(SNPARGS(proto, len), "%s", 559 inet_ntoa(ip->ip_src)); 560 snprintf(SNPARGS(proto, len), " %s", 561 inet_ntoa(ip->ip_dst)); 562 break; 563 564 default: 565 len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 566 inet_ntoa(ip->ip_src)); 567 snprintf(SNPARGS(proto, len), " %s", 568 inet_ntoa(ip->ip_dst)); 569 break; 570 } 571 572 if (ip_off & (IP_MF | IP_OFFMASK)) 573 snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 574 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 575 offset << 3, 576 (ip_off & IP_MF) ? "+" : ""); 577 } 578 if (oif || m->m_pkthdr.rcvif) 579 log(LOG_SECURITY | LOG_INFO, 580 "ipfw: %d %s %s %s via %s%s\n", 581 f ? f->rulenum : -1, 582 action, proto, oif ? "out" : "in", 583 oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 584 fragment); 585 else 586 log(LOG_SECURITY | LOG_INFO, 587 "ipfw: %d %s %s [no if info]%s\n", 588 f ? f->rulenum : -1, 589 action, proto, fragment); 590 if (limit_reached) 591 log(LOG_SECURITY | LOG_NOTICE, 592 "ipfw: limit %d reached on entry %d\n", 593 limit_reached, f ? f->rulenum : -1); 594 } 595 596 /* 597 * IMPORTANT: the hash function for dynamic rules must be commutative 598 * in source and destination (ip,port), because rules are bidirectional 599 * and we want to find both in the same bucket. 600 */ 601 static __inline int 602 hash_packet(struct ipfw_flow_id *id) 603 { 604 u_int32_t i; 605 606 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 607 i &= (curr_dyn_buckets - 1); 608 return i; 609 } 610 611 /** 612 * unlink a dynamic rule from a chain. prev is a pointer to 613 * the previous one, q is a pointer to the rule to delete, 614 * head is a pointer to the head of the queue. 615 * Modifies q and potentially also head. 616 */ 617 #define UNLINK_DYN_RULE(prev, head, q) { \ 618 ipfw_dyn_rule *old_q = q; \ 619 \ 620 /* remove a refcount to the parent */ \ 621 if (q->dyn_type == O_LIMIT) \ 622 q->parent->count--; \ 623 DEB(printf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \ 624 (q->id.src_ip), (q->id.src_port), \ 625 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 626 if (prev != NULL) \ 627 prev->next = q = q->next; \ 628 else \ 629 head = q = q->next; \ 630 dyn_count--; \ 631 free(old_q, M_IPFW); } 632 633 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 634 635 /** 636 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 637 * 638 * If keep_me == NULL, rules are deleted even if not expired, 639 * otherwise only expired rules are removed. 640 * 641 * The value of the second parameter is also used to point to identify 642 * a rule we absolutely do not want to remove (e.g. because we are 643 * holding a reference to it -- this is the case with O_LIMIT_PARENT 644 * rules). The pointer is only used for comparison, so any non-null 645 * value will do. 646 */ 647 static void 648 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 649 { 650 static u_int32_t last_remove = 0; 651 652 #define FORCE (keep_me == NULL) 653 654 ipfw_dyn_rule *prev, *q; 655 int i, pass = 0, max_pass = 0; 656 657 if (ipfw_dyn_v == NULL || dyn_count == 0) 658 return; 659 /* do not expire more than once per second, it is useless */ 660 if (!FORCE && last_remove == time_second) 661 return; 662 last_remove = time_second; 663 664 /* 665 * because O_LIMIT refer to parent rules, during the first pass only 666 * remove child and mark any pending LIMIT_PARENT, and remove 667 * them in a second pass. 668 */ 669 next_pass: 670 for (i = 0 ; i < curr_dyn_buckets ; i++) { 671 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 672 /* 673 * Logic can become complex here, so we split tests. 674 */ 675 if (q == keep_me) 676 goto next; 677 if (rule != NULL && rule != q->rule) 678 goto next; /* not the one we are looking for */ 679 if (q->dyn_type == O_LIMIT_PARENT) { 680 /* 681 * handle parent in the second pass, 682 * record we need one. 683 */ 684 max_pass = 1; 685 if (pass == 0) 686 goto next; 687 if (FORCE && q->count != 0 ) { 688 /* XXX should not happen! */ 689 printf( "OUCH! cannot remove rule," 690 " count %d\n", q->count); 691 } 692 } else { 693 if (!FORCE && 694 !TIME_LEQ( q->expire, time_second )) 695 goto next; 696 } 697 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 698 continue; 699 next: 700 prev=q; 701 q=q->next; 702 } 703 } 704 if (pass++ < max_pass) 705 goto next_pass; 706 } 707 708 709 /** 710 * lookup a dynamic rule. 711 */ 712 static ipfw_dyn_rule * 713 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 714 struct tcphdr *tcp) 715 { 716 /* 717 * stateful ipfw extensions. 718 * Lookup into dynamic session queue 719 */ 720 #define MATCH_REVERSE 0 721 #define MATCH_FORWARD 1 722 #define MATCH_NONE 2 723 #define MATCH_UNKNOWN 3 724 int i, dir = MATCH_NONE; 725 ipfw_dyn_rule *prev, *q=NULL; 726 727 if (ipfw_dyn_v == NULL) 728 goto done; /* not found */ 729 i = hash_packet( pkt ); 730 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 731 if (q->dyn_type == O_LIMIT_PARENT) 732 goto next; 733 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 734 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 735 continue; 736 } 737 if ( pkt->proto == q->id.proto) { 738 if (pkt->src_ip == q->id.src_ip && 739 pkt->dst_ip == q->id.dst_ip && 740 pkt->src_port == q->id.src_port && 741 pkt->dst_port == q->id.dst_port ) { 742 dir = MATCH_FORWARD; 743 break; 744 } 745 if (pkt->src_ip == q->id.dst_ip && 746 pkt->dst_ip == q->id.src_ip && 747 pkt->src_port == q->id.dst_port && 748 pkt->dst_port == q->id.src_port ) { 749 dir = MATCH_REVERSE; 750 break; 751 } 752 } 753 next: 754 prev = q; 755 q = q->next; 756 } 757 if (q == NULL) 758 goto done; /* q = NULL, not found */ 759 760 if ( prev != NULL) { /* found and not in front */ 761 prev->next = q->next; 762 q->next = ipfw_dyn_v[i]; 763 ipfw_dyn_v[i] = q; 764 } 765 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 766 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 767 768 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 769 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 770 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 771 switch (q->state) { 772 case TH_SYN: /* opening */ 773 q->expire = time_second + dyn_syn_lifetime; 774 break; 775 776 case BOTH_SYN: /* move to established */ 777 case BOTH_SYN | TH_FIN : /* one side tries to close */ 778 case BOTH_SYN | (TH_FIN << 8) : 779 if (tcp) { 780 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 781 u_int32_t ack = ntohl(tcp->th_ack); 782 if (dir == MATCH_FORWARD) { 783 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 784 q->ack_fwd = ack; 785 else { /* ignore out-of-sequence */ 786 break; 787 } 788 } else { 789 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 790 q->ack_rev = ack; 791 else { /* ignore out-of-sequence */ 792 break; 793 } 794 } 795 } 796 q->expire = time_second + dyn_ack_lifetime; 797 break; 798 799 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 800 if (dyn_fin_lifetime >= dyn_keepalive_period) 801 dyn_fin_lifetime = dyn_keepalive_period - 1; 802 q->expire = time_second + dyn_fin_lifetime; 803 break; 804 805 default: 806 #if 0 807 /* 808 * reset or some invalid combination, but can also 809 * occur if we use keep-state the wrong way. 810 */ 811 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 812 printf("invalid state: 0x%x\n", q->state); 813 #endif 814 if (dyn_rst_lifetime >= dyn_keepalive_period) 815 dyn_rst_lifetime = dyn_keepalive_period - 1; 816 q->expire = time_second + dyn_rst_lifetime; 817 break; 818 } 819 } else if (pkt->proto == IPPROTO_UDP) { 820 q->expire = time_second + dyn_udp_lifetime; 821 } else { 822 /* other protocols */ 823 q->expire = time_second + dyn_short_lifetime; 824 } 825 done: 826 if (match_direction) 827 *match_direction = dir; 828 return q; 829 } 830 831 static void 832 realloc_dynamic_table(void) 833 { 834 /* 835 * Try reallocation, make sure we have a power of 2 and do 836 * not allow more than 64k entries. In case of overflow, 837 * default to 1024. 838 */ 839 840 if (dyn_buckets > 65536) 841 dyn_buckets = 1024; 842 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 843 dyn_buckets = curr_dyn_buckets; /* reset */ 844 return; 845 } 846 curr_dyn_buckets = dyn_buckets; 847 if (ipfw_dyn_v != NULL) 848 free(ipfw_dyn_v, M_IPFW); 849 for (;;) { 850 ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 851 M_IPFW, M_NOWAIT | M_ZERO); 852 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 853 break; 854 curr_dyn_buckets /= 2; 855 } 856 } 857 858 /** 859 * Install state of type 'type' for a dynamic session. 860 * The hash table contains two type of rules: 861 * - regular rules (O_KEEP_STATE) 862 * - rules for sessions with limited number of sess per user 863 * (O_LIMIT). When they are created, the parent is 864 * increased by 1, and decreased on delete. In this case, 865 * the third parameter is the parent rule and not the chain. 866 * - "parent" rules for the above (O_LIMIT_PARENT). 867 */ 868 static ipfw_dyn_rule * 869 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 870 { 871 ipfw_dyn_rule *r; 872 int i; 873 874 if (ipfw_dyn_v == NULL || 875 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 876 realloc_dynamic_table(); 877 if (ipfw_dyn_v == NULL) 878 return NULL; /* failed ! */ 879 } 880 i = hash_packet(id); 881 882 r = malloc(sizeof *r, M_IPFW, M_NOWAIT | M_ZERO); 883 if (r == NULL) { 884 printf ("sorry cannot allocate state\n"); 885 return NULL; 886 } 887 888 /* increase refcount on parent, and set pointer */ 889 if (dyn_type == O_LIMIT) { 890 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 891 if ( parent->dyn_type != O_LIMIT_PARENT) 892 panic("invalid parent"); 893 parent->count++; 894 r->parent = parent; 895 rule = parent->rule; 896 } 897 898 r->id = *id; 899 r->expire = time_second + dyn_syn_lifetime; 900 r->rule = rule; 901 r->dyn_type = dyn_type; 902 r->pcnt = r->bcnt = 0; 903 r->count = 0; 904 905 r->bucket = i; 906 r->next = ipfw_dyn_v[i]; 907 ipfw_dyn_v[i] = r; 908 dyn_count++; 909 DEB(printf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 910 dyn_type, 911 (r->id.src_ip), (r->id.src_port), 912 (r->id.dst_ip), (r->id.dst_port), 913 dyn_count ); ) 914 return r; 915 } 916 917 /** 918 * lookup dynamic parent rule using pkt and rule as search keys. 919 * If the lookup fails, then install one. 920 */ 921 static ipfw_dyn_rule * 922 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 923 { 924 ipfw_dyn_rule *q; 925 int i; 926 927 if (ipfw_dyn_v) { 928 i = hash_packet( pkt ); 929 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 930 if (q->dyn_type == O_LIMIT_PARENT && 931 rule== q->rule && 932 pkt->proto == q->id.proto && 933 pkt->src_ip == q->id.src_ip && 934 pkt->dst_ip == q->id.dst_ip && 935 pkt->src_port == q->id.src_port && 936 pkt->dst_port == q->id.dst_port) { 937 q->expire = time_second + dyn_short_lifetime; 938 DEB(printf("lookup_dyn_parent found 0x%p\n",q);) 939 return q; 940 } 941 } 942 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 943 } 944 945 /** 946 * Install dynamic state for rule type cmd->o.opcode 947 * 948 * Returns 1 (failure) if state is not installed because of errors or because 949 * session limitations are enforced. 950 */ 951 static int 952 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 953 struct ip_fw_args *args) 954 { 955 static int last_log; 956 957 ipfw_dyn_rule *q; 958 959 DEB(printf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", 960 cmd->o.opcode, 961 (args->f_id.src_ip), (args->f_id.src_port), 962 (args->f_id.dst_ip), (args->f_id.dst_port) );) 963 964 q = lookup_dyn_rule(&args->f_id, NULL, NULL); 965 966 if (q != NULL) { /* should never occur */ 967 if (last_log != time_second) { 968 last_log = time_second; 969 printf(" install_state: entry already present, done\n"); 970 } 971 return 0; 972 } 973 974 if (dyn_count >= dyn_max) 975 /* 976 * Run out of slots, try to remove any expired rule. 977 */ 978 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 979 980 if (dyn_count >= dyn_max) { 981 if (last_log != time_second) { 982 last_log = time_second; 983 printf("install_state: Too many dynamic rules\n"); 984 } 985 return 1; /* cannot install, notify caller */ 986 } 987 988 switch (cmd->o.opcode) { 989 case O_KEEP_STATE: /* bidir rule */ 990 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 991 break; 992 993 case O_LIMIT: /* limit number of sessions */ 994 { 995 u_int16_t limit_mask = cmd->limit_mask; 996 struct ipfw_flow_id id; 997 ipfw_dyn_rule *parent; 998 999 DEB(printf("installing dyn-limit rule %d\n", cmd->conn_limit);) 1000 1001 id.dst_ip = id.src_ip = 0; 1002 id.dst_port = id.src_port = 0; 1003 id.proto = args->f_id.proto; 1004 1005 if (limit_mask & DYN_SRC_ADDR) 1006 id.src_ip = args->f_id.src_ip; 1007 if (limit_mask & DYN_DST_ADDR) 1008 id.dst_ip = args->f_id.dst_ip; 1009 if (limit_mask & DYN_SRC_PORT) 1010 id.src_port = args->f_id.src_port; 1011 if (limit_mask & DYN_DST_PORT) 1012 id.dst_port = args->f_id.dst_port; 1013 parent = lookup_dyn_parent(&id, rule); 1014 if (parent == NULL) { 1015 printf("add parent failed\n"); 1016 return 1; 1017 } 1018 if (parent->count >= cmd->conn_limit) { 1019 /* 1020 * See if we can remove some expired rule. 1021 */ 1022 remove_dyn_rule(rule, parent); 1023 if (parent->count >= cmd->conn_limit) { 1024 if (fw_verbose && last_log != time_second) { 1025 last_log = time_second; 1026 log(LOG_SECURITY | LOG_DEBUG, 1027 "drop session, too many entries\n"); 1028 } 1029 return 1; 1030 } 1031 } 1032 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1033 } 1034 break; 1035 default: 1036 printf("unknown dynamic rule type %u\n", cmd->o.opcode); 1037 return 1; 1038 } 1039 lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1040 return 0; 1041 } 1042 1043 /* 1044 * Transmit a TCP packet, containing either a RST or a keepalive. 1045 * When flags & TH_RST, we are sending a RST packet, because of a 1046 * "reset" action matched the packet. 1047 * Otherwise we are sending a keepalive, and flags & TH_ 1048 */ 1049 static void 1050 send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1051 { 1052 struct mbuf *m; 1053 struct ip *ip; 1054 struct tcphdr *tcp; 1055 struct route sro; /* fake route */ 1056 1057 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1058 if (m == 0) 1059 return; 1060 m->m_pkthdr.rcvif = (struct ifnet *)0; 1061 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1062 m->m_data += max_linkhdr; 1063 1064 ip = mtod(m, struct ip *); 1065 bzero(ip, m->m_len); 1066 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1067 ip->ip_p = IPPROTO_TCP; 1068 tcp->th_off = 5; 1069 /* 1070 * Assume we are sending a RST (or a keepalive in the reverse 1071 * direction), swap src and destination addresses and ports. 1072 */ 1073 ip->ip_src.s_addr = htonl(id->dst_ip); 1074 ip->ip_dst.s_addr = htonl(id->src_ip); 1075 tcp->th_sport = htons(id->dst_port); 1076 tcp->th_dport = htons(id->src_port); 1077 if (flags & TH_RST) { /* we are sending a RST */ 1078 if (flags & TH_ACK) { 1079 tcp->th_seq = htonl(ack); 1080 tcp->th_ack = htonl(0); 1081 tcp->th_flags = TH_RST; 1082 } else { 1083 if (flags & TH_SYN) 1084 seq++; 1085 tcp->th_seq = htonl(0); 1086 tcp->th_ack = htonl(seq); 1087 tcp->th_flags = TH_RST | TH_ACK; 1088 } 1089 } else { 1090 /* 1091 * We are sending a keepalive. flags & TH_SYN determines 1092 * the direction, forward if set, reverse if clear. 1093 * NOTE: seq and ack are always assumed to be correct 1094 * as set by the caller. This may be confusing... 1095 */ 1096 if (flags & TH_SYN) { 1097 /* 1098 * we have to rewrite the correct addresses! 1099 */ 1100 ip->ip_dst.s_addr = htonl(id->dst_ip); 1101 ip->ip_src.s_addr = htonl(id->src_ip); 1102 tcp->th_dport = htons(id->dst_port); 1103 tcp->th_sport = htons(id->src_port); 1104 } 1105 tcp->th_seq = htonl(seq); 1106 tcp->th_ack = htonl(ack); 1107 tcp->th_flags = TH_ACK; 1108 } 1109 /* 1110 * set ip_len to the payload size so we can compute 1111 * the tcp checksum on the pseudoheader 1112 * XXX check this, could save a couple of words ? 1113 */ 1114 ip->ip_len = htons(sizeof(struct tcphdr)); 1115 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1116 /* 1117 * now fill fields left out earlier 1118 */ 1119 ip->ip_ttl = ip_defttl; 1120 ip->ip_len = m->m_pkthdr.len; 1121 bzero (&sro, sizeof (sro)); 1122 ip_rtaddr(ip->ip_dst, &sro); 1123 m->m_flags |= M_SKIP_FIREWALL; 1124 ip_output(m, NULL, &sro, 0, NULL, NULL); 1125 if (sro.ro_rt) 1126 RTFREE(sro.ro_rt); 1127 } 1128 1129 /* 1130 * sends a reject message, consuming the mbuf passed as an argument. 1131 */ 1132 static void 1133 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1134 { 1135 1136 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1137 /* We need the IP header in host order for icmp_error(). */ 1138 if (args->eh != NULL) { 1139 struct ip *ip = mtod(args->m, struct ip *); 1140 ip->ip_len = ntohs(ip->ip_len); 1141 ip->ip_off = ntohs(ip->ip_off); 1142 } 1143 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1144 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1145 struct tcphdr *const tcp = 1146 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1147 if ( (tcp->th_flags & TH_RST) == 0) 1148 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1149 ntohl(tcp->th_ack), 1150 tcp->th_flags | TH_RST); 1151 m_freem(args->m); 1152 } else 1153 m_freem(args->m); 1154 args->m = NULL; 1155 } 1156 1157 /** 1158 * 1159 * Given an ip_fw *, lookup_next_rule will return a pointer 1160 * to the next rule, which can be either the jump 1161 * target (for skipto instructions) or the next one in the list (in 1162 * all other cases including a missing jump target). 1163 * The result is also written in the "next_rule" field of the rule. 1164 * Backward jumps are not allowed, so start looking from the next 1165 * rule... 1166 * 1167 * This never returns NULL -- in case we do not have an exact match, 1168 * the next rule is returned. When the ruleset is changed, 1169 * pointers are flushed so we are always correct. 1170 */ 1171 1172 static struct ip_fw * 1173 lookup_next_rule(struct ip_fw *me) 1174 { 1175 struct ip_fw *rule = NULL; 1176 ipfw_insn *cmd; 1177 1178 /* look for action, in case it is a skipto */ 1179 cmd = ACTION_PTR(me); 1180 if (cmd->opcode == O_LOG) 1181 cmd += F_LEN(cmd); 1182 if ( cmd->opcode == O_SKIPTO ) 1183 for (rule = me->next; rule ; rule = rule->next) 1184 if (rule->rulenum >= cmd->arg1) 1185 break; 1186 if (rule == NULL) /* failure or not a skipto */ 1187 rule = me->next; 1188 me->next_rule = rule; 1189 return rule; 1190 } 1191 1192 /* 1193 * The main check routine for the firewall. 1194 * 1195 * All arguments are in args so we can modify them and return them 1196 * back to the caller. 1197 * 1198 * Parameters: 1199 * 1200 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1201 * Starts with the IP header. 1202 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1203 * args->oif Outgoing interface, or NULL if packet is incoming. 1204 * The incoming interface is in the mbuf. (in) 1205 * args->divert_rule (in/out) 1206 * Skip up to the first rule past this rule number; 1207 * upon return, non-zero port number for divert or tee. 1208 * 1209 * args->rule Pointer to the last matching rule (in/out) 1210 * args->next_hop Socket we are forwarding to (out). 1211 * args->f_id Addresses grabbed from the packet (out) 1212 * 1213 * Return value: 1214 * 1215 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1216 * 0 The packet is to be accepted and routed normally OR 1217 * the packet was denied/rejected and has been dropped; 1218 * in the latter case, *m is equal to NULL upon return. 1219 * port Divert the packet to port, with these caveats: 1220 * 1221 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1222 * of diverting it (ie, 'ipfw tee'). 1223 * 1224 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1225 * 16 bits as a dummynet pipe number instead of diverting 1226 */ 1227 1228 static int 1229 ipfw_chk(struct ip_fw_args *args) 1230 { 1231 /* 1232 * Local variables hold state during the processing of a packet. 1233 * 1234 * IMPORTANT NOTE: to speed up the processing of rules, there 1235 * are some assumption on the values of the variables, which 1236 * are documented here. Should you change them, please check 1237 * the implementation of the various instructions to make sure 1238 * that they still work. 1239 * 1240 * args->eh The MAC header. It is non-null for a layer2 1241 * packet, it is NULL for a layer-3 packet. 1242 * 1243 * m | args->m Pointer to the mbuf, as received from the caller. 1244 * It may change if ipfw_chk() does an m_pullup, or if it 1245 * consumes the packet because it calls send_reject(). 1246 * XXX This has to change, so that ipfw_chk() never modifies 1247 * or consumes the buffer. 1248 * ip is simply an alias of the value of m, and it is kept 1249 * in sync with it (the packet is supposed to start with 1250 * the ip header). 1251 */ 1252 struct mbuf *m = args->m; 1253 struct ip *ip = mtod(m, struct ip *); 1254 1255 /* 1256 * oif | args->oif If NULL, ipfw_chk has been called on the 1257 * inbound path (ether_input, bdg_forward, ip_input). 1258 * If non-NULL, ipfw_chk has been called on the outbound path 1259 * (ether_output, ip_output). 1260 */ 1261 struct ifnet *oif = args->oif; 1262 1263 struct ip_fw *f = NULL; /* matching rule */ 1264 int retval = 0; 1265 1266 /* 1267 * hlen The length of the IPv4 header. 1268 * hlen >0 means we have an IPv4 packet. 1269 */ 1270 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1271 1272 /* 1273 * offset The offset of a fragment. offset != 0 means that 1274 * we have a fragment at this offset of an IPv4 packet. 1275 * offset == 0 means that (if this is an IPv4 packet) 1276 * this is the first or only fragment. 1277 */ 1278 u_short offset = 0; 1279 1280 /* 1281 * Local copies of addresses. They are only valid if we have 1282 * an IP packet. 1283 * 1284 * proto The protocol. Set to 0 for non-ip packets, 1285 * or to the protocol read from the packet otherwise. 1286 * proto != 0 means that we have an IPv4 packet. 1287 * 1288 * src_port, dst_port port numbers, in HOST format. Only 1289 * valid for TCP and UDP packets. 1290 * 1291 * src_ip, dst_ip ip addresses, in NETWORK format. 1292 * Only valid for IPv4 packets. 1293 */ 1294 u_int8_t proto; 1295 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1296 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1297 u_int16_t ip_len=0; 1298 int dyn_dir = MATCH_UNKNOWN; 1299 ipfw_dyn_rule *q = NULL; 1300 1301 if (m->m_flags & M_SKIP_FIREWALL) 1302 return 0; /* accept */ 1303 /* 1304 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1305 * MATCH_NONE when checked and not matched (q = NULL), 1306 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1307 */ 1308 1309 if (args->eh == NULL || /* layer 3 packet */ 1310 ( m->m_pkthdr.len >= sizeof(struct ip) && 1311 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1312 hlen = ip->ip_hl << 2; 1313 1314 /* 1315 * Collect parameters into local variables for faster matching. 1316 */ 1317 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1318 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1319 goto after_ip_checks; 1320 } 1321 1322 proto = args->f_id.proto = ip->ip_p; 1323 src_ip = ip->ip_src; 1324 dst_ip = ip->ip_dst; 1325 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1326 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1327 ip_len = ntohs(ip->ip_len); 1328 } else { 1329 offset = ip->ip_off & IP_OFFMASK; 1330 ip_len = ip->ip_len; 1331 } 1332 1333 #define PULLUP_TO(len) \ 1334 do { \ 1335 if ((m)->m_len < (len)) { \ 1336 args->m = m = m_pullup(m, (len)); \ 1337 if (m == 0) \ 1338 goto pullup_failed; \ 1339 ip = mtod(m, struct ip *); \ 1340 } \ 1341 } while (0) 1342 1343 if (offset == 0) { 1344 switch (proto) { 1345 case IPPROTO_TCP: 1346 { 1347 struct tcphdr *tcp; 1348 1349 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1350 tcp = L3HDR(struct tcphdr, ip); 1351 dst_port = tcp->th_dport; 1352 src_port = tcp->th_sport; 1353 args->f_id.flags = tcp->th_flags; 1354 } 1355 break; 1356 1357 case IPPROTO_UDP: 1358 { 1359 struct udphdr *udp; 1360 1361 PULLUP_TO(hlen + sizeof(struct udphdr)); 1362 udp = L3HDR(struct udphdr, ip); 1363 dst_port = udp->uh_dport; 1364 src_port = udp->uh_sport; 1365 } 1366 break; 1367 1368 case IPPROTO_ICMP: 1369 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1370 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1371 break; 1372 1373 default: 1374 break; 1375 } 1376 #undef PULLUP_TO 1377 } 1378 1379 args->f_id.src_ip = ntohl(src_ip.s_addr); 1380 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1381 args->f_id.src_port = src_port = ntohs(src_port); 1382 args->f_id.dst_port = dst_port = ntohs(dst_port); 1383 1384 after_ip_checks: 1385 if (args->rule) { 1386 /* 1387 * Packet has already been tagged. Look for the next rule 1388 * to restart processing. 1389 * 1390 * If fw_one_pass != 0 then just accept it. 1391 * XXX should not happen here, but optimized out in 1392 * the caller. 1393 */ 1394 if (fw_one_pass) 1395 return 0; 1396 1397 f = args->rule->next_rule; 1398 if (f == NULL) 1399 f = lookup_next_rule(args->rule); 1400 } else { 1401 /* 1402 * Find the starting rule. It can be either the first 1403 * one, or the one after divert_rule if asked so. 1404 */ 1405 int skipto = args->divert_rule; 1406 1407 f = layer3_chain; 1408 if (args->eh == NULL && skipto != 0) { 1409 if (skipto >= IPFW_DEFAULT_RULE) 1410 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1411 while (f && f->rulenum <= skipto) 1412 f = f->next; 1413 if (f == NULL) /* drop packet */ 1414 return(IP_FW_PORT_DENY_FLAG); 1415 } 1416 } 1417 args->divert_rule = 0; /* reset to avoid confusion later */ 1418 1419 /* 1420 * Now scan the rules, and parse microinstructions for each rule. 1421 */ 1422 for (; f; f = f->next) { 1423 int l, cmdlen; 1424 ipfw_insn *cmd; 1425 int skip_or; /* skip rest of OR block */ 1426 1427 again: 1428 if (set_disable & (1 << f->set) ) 1429 continue; 1430 1431 skip_or = 0; 1432 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1433 l -= cmdlen, cmd += cmdlen) { 1434 int match; 1435 1436 /* 1437 * check_body is a jump target used when we find a 1438 * CHECK_STATE, and need to jump to the body of 1439 * the target rule. 1440 */ 1441 1442 check_body: 1443 cmdlen = F_LEN(cmd); 1444 /* 1445 * An OR block (insn_1 || .. || insn_n) has the 1446 * F_OR bit set in all but the last instruction. 1447 * The first match will set "skip_or", and cause 1448 * the following instructions to be skipped until 1449 * past the one with the F_OR bit clear. 1450 */ 1451 if (skip_or) { /* skip this instruction */ 1452 if ((cmd->len & F_OR) == 0) 1453 skip_or = 0; /* next one is good */ 1454 continue; 1455 } 1456 match = 0; /* set to 1 if we succeed */ 1457 1458 switch (cmd->opcode) { 1459 /* 1460 * The first set of opcodes compares the packet's 1461 * fields with some pattern, setting 'match' if a 1462 * match is found. At the end of the loop there is 1463 * logic to deal with F_NOT and F_OR flags associated 1464 * with the opcode. 1465 */ 1466 case O_NOP: 1467 match = 1; 1468 break; 1469 1470 case O_FORWARD_MAC: 1471 printf("ipfw: opcode %d unimplemented\n", 1472 cmd->opcode); 1473 break; 1474 1475 case O_GID: 1476 case O_UID: 1477 /* 1478 * We only check offset == 0 && proto != 0, 1479 * as this ensures that we have an IPv4 1480 * packet with the ports info. 1481 */ 1482 if (offset!=0) 1483 break; 1484 { 1485 struct inpcbinfo *pi; 1486 int wildcard; 1487 struct inpcb *pcb; 1488 1489 if (proto == IPPROTO_TCP) { 1490 wildcard = 0; 1491 pi = &tcbinfo; 1492 } else if (proto == IPPROTO_UDP) { 1493 wildcard = 1; 1494 pi = &udbinfo; 1495 } else 1496 break; 1497 1498 pcb = (oif) ? 1499 in_pcblookup_hash(pi, 1500 dst_ip, htons(dst_port), 1501 src_ip, htons(src_port), 1502 wildcard, oif) : 1503 in_pcblookup_hash(pi, 1504 src_ip, htons(src_port), 1505 dst_ip, htons(dst_port), 1506 wildcard, NULL); 1507 1508 if (pcb == NULL || pcb->inp_socket == NULL) 1509 break; 1510 #if __FreeBSD_version < 500034 1511 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1512 #endif 1513 if (cmd->opcode == O_UID) { 1514 match = 1515 !socheckuid(pcb->inp_socket, 1516 (uid_t)((ipfw_insn_u32 *)cmd)->d[0]); 1517 } else { 1518 match = groupmember( 1519 (uid_t)((ipfw_insn_u32 *)cmd)->d[0], 1520 pcb->inp_socket->so_cred); 1521 } 1522 } 1523 break; 1524 1525 case O_RECV: 1526 match = iface_match(m->m_pkthdr.rcvif, 1527 (ipfw_insn_if *)cmd); 1528 break; 1529 1530 case O_XMIT: 1531 match = iface_match(oif, (ipfw_insn_if *)cmd); 1532 break; 1533 1534 case O_VIA: 1535 match = iface_match(oif ? oif : 1536 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1537 break; 1538 1539 case O_MACADDR2: 1540 if (args->eh != NULL) { /* have MAC header */ 1541 u_int32_t *want = (u_int32_t *) 1542 ((ipfw_insn_mac *)cmd)->addr; 1543 u_int32_t *mask = (u_int32_t *) 1544 ((ipfw_insn_mac *)cmd)->mask; 1545 u_int32_t *hdr = (u_int32_t *)args->eh; 1546 1547 match = 1548 ( want[0] == (hdr[0] & mask[0]) && 1549 want[1] == (hdr[1] & mask[1]) && 1550 want[2] == (hdr[2] & mask[2]) ); 1551 } 1552 break; 1553 1554 case O_MAC_TYPE: 1555 if (args->eh != NULL) { 1556 u_int16_t t = 1557 ntohs(args->eh->ether_type); 1558 u_int16_t *p = 1559 ((ipfw_insn_u16 *)cmd)->ports; 1560 int i; 1561 1562 for (i = cmdlen - 1; !match && i>0; 1563 i--, p += 2) 1564 match = (t>=p[0] && t<=p[1]); 1565 } 1566 break; 1567 1568 case O_FRAG: 1569 match = (hlen > 0 && offset != 0); 1570 break; 1571 1572 case O_IN: /* "out" is "not in" */ 1573 match = (oif == NULL); 1574 break; 1575 1576 case O_LAYER2: 1577 match = (args->eh != NULL); 1578 break; 1579 1580 case O_PROTO: 1581 /* 1582 * We do not allow an arg of 0 so the 1583 * check of "proto" only suffices. 1584 */ 1585 match = (proto == cmd->arg1); 1586 break; 1587 1588 case O_IP_SRC: 1589 match = (hlen > 0 && 1590 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1591 src_ip.s_addr); 1592 break; 1593 1594 case O_IP_SRC_MASK: 1595 match = (hlen > 0 && 1596 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1597 (src_ip.s_addr & 1598 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1599 break; 1600 1601 case O_IP_SRC_ME: 1602 if (hlen > 0) { 1603 struct ifnet *tif; 1604 1605 INADDR_TO_IFP(src_ip, tif); 1606 match = (tif != NULL); 1607 } 1608 break; 1609 1610 case O_IP_DST_SET: 1611 case O_IP_SRC_SET: 1612 if (hlen > 0) { 1613 u_int32_t *d = (u_int32_t *)(cmd+1); 1614 u_int32_t addr = 1615 cmd->opcode == O_IP_DST_SET ? 1616 args->f_id.dst_ip : 1617 args->f_id.src_ip; 1618 1619 if (addr < d[0]) 1620 break; 1621 addr -= d[0]; /* subtract base */ 1622 match = (addr < cmd->arg1) && 1623 ( d[ 1 + (addr>>5)] & 1624 (1<<(addr & 0x1f)) ); 1625 } 1626 break; 1627 1628 case O_IP_DST: 1629 match = (hlen > 0 && 1630 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1631 dst_ip.s_addr); 1632 break; 1633 1634 case O_IP_DST_MASK: 1635 match = (hlen > 0) && 1636 (((ipfw_insn_ip *)cmd)->addr.s_addr == 1637 (dst_ip.s_addr & 1638 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1639 break; 1640 1641 case O_IP_DST_ME: 1642 if (hlen > 0) { 1643 struct ifnet *tif; 1644 1645 INADDR_TO_IFP(dst_ip, tif); 1646 match = (tif != NULL); 1647 } 1648 break; 1649 1650 case O_IP_SRCPORT: 1651 case O_IP_DSTPORT: 1652 /* 1653 * offset == 0 && proto != 0 is enough 1654 * to guarantee that we have an IPv4 1655 * packet with port info. 1656 */ 1657 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1658 && offset == 0) { 1659 u_int16_t x = 1660 (cmd->opcode == O_IP_SRCPORT) ? 1661 src_port : dst_port ; 1662 u_int16_t *p = 1663 ((ipfw_insn_u16 *)cmd)->ports; 1664 int i; 1665 1666 for (i = cmdlen - 1; !match && i>0; 1667 i--, p += 2) 1668 match = (x>=p[0] && x<=p[1]); 1669 } 1670 break; 1671 1672 case O_ICMPTYPE: 1673 match = (offset == 0 && proto==IPPROTO_ICMP && 1674 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1675 break; 1676 1677 case O_IPOPT: 1678 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1679 break; 1680 1681 case O_IPVER: 1682 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1683 break; 1684 1685 case O_IPTTL: 1686 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl); 1687 break; 1688 1689 case O_IPID: 1690 match = (hlen > 0 && 1691 cmd->arg1 == ntohs(ip->ip_id)); 1692 break; 1693 1694 case O_IPLEN: 1695 match = (hlen > 0 && cmd->arg1 == ip_len); 1696 break; 1697 1698 case O_IPPRECEDENCE: 1699 match = (hlen > 0 && 1700 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1701 break; 1702 1703 case O_IPTOS: 1704 match = (hlen > 0 && 1705 flags_match(cmd, ip->ip_tos)); 1706 break; 1707 1708 case O_TCPFLAGS: 1709 match = (proto == IPPROTO_TCP && offset == 0 && 1710 flags_match(cmd, 1711 L3HDR(struct tcphdr,ip)->th_flags)); 1712 break; 1713 1714 case O_TCPOPTS: 1715 match = (proto == IPPROTO_TCP && offset == 0 && 1716 tcpopts_match(ip, cmd)); 1717 break; 1718 1719 case O_TCPSEQ: 1720 match = (proto == IPPROTO_TCP && offset == 0 && 1721 ((ipfw_insn_u32 *)cmd)->d[0] == 1722 L3HDR(struct tcphdr,ip)->th_seq); 1723 break; 1724 1725 case O_TCPACK: 1726 match = (proto == IPPROTO_TCP && offset == 0 && 1727 ((ipfw_insn_u32 *)cmd)->d[0] == 1728 L3HDR(struct tcphdr,ip)->th_ack); 1729 break; 1730 1731 case O_TCPWIN: 1732 match = (proto == IPPROTO_TCP && offset == 0 && 1733 cmd->arg1 == 1734 L3HDR(struct tcphdr,ip)->th_win); 1735 break; 1736 1737 case O_ESTAB: 1738 /* reject packets which have SYN only */ 1739 /* XXX should i also check for TH_ACK ? */ 1740 match = (proto == IPPROTO_TCP && offset == 0 && 1741 (L3HDR(struct tcphdr,ip)->th_flags & 1742 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1743 break; 1744 1745 case O_LOG: 1746 if (fw_verbose) 1747 ipfw_log(f, hlen, args->eh, m, oif); 1748 match = 1; 1749 break; 1750 1751 case O_PROB: 1752 match = (random()<((ipfw_insn_u32 *)cmd)->d[0]); 1753 break; 1754 1755 /* 1756 * The second set of opcodes represents 'actions', 1757 * i.e. the terminal part of a rule once the packet 1758 * matches all previous patterns. 1759 * Typically there is only one action for each rule, 1760 * and the opcode is stored at the end of the rule 1761 * (but there are exceptions -- see below). 1762 * 1763 * In general, here we set retval and terminate the 1764 * outer loop (would be a 'break 3' in some language, 1765 * but we need to do a 'goto done'). 1766 * 1767 * Exceptions: 1768 * O_COUNT and O_SKIPTO actions: 1769 * instead of terminating, we jump to the next rule 1770 * ('goto next_rule', equivalent to a 'break 2'), 1771 * or to the SKIPTO target ('goto again' after 1772 * having set f, cmd and l), respectively. 1773 * 1774 * O_LIMIT and O_KEEP_STATE: these opcodes are 1775 * not real 'actions', and are stored right 1776 * before the 'action' part of the rule. 1777 * These opcodes try to install an entry in the 1778 * state tables; if successful, we continue with 1779 * the next opcode (match=1; break;), otherwise 1780 * the packet * must be dropped 1781 * ('goto done' after setting retval); 1782 * 1783 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1784 * cause a lookup of the state table, and a jump 1785 * to the 'action' part of the parent rule 1786 * ('goto check_body') if an entry is found, or 1787 * (CHECK_STATE only) a jump to the next rule if 1788 * the entry is not found ('goto next_rule'). 1789 * The result of the lookup is cached to make 1790 * further instances of these opcodes are 1791 * effectively NOPs. 1792 */ 1793 case O_LIMIT: 1794 case O_KEEP_STATE: 1795 if (install_state(f, 1796 (ipfw_insn_limit *)cmd, args)) { 1797 retval = IP_FW_PORT_DENY_FLAG; 1798 goto done; /* error/limit violation */ 1799 } 1800 match = 1; 1801 break; 1802 1803 case O_PROBE_STATE: 1804 case O_CHECK_STATE: 1805 /* 1806 * dynamic rules are checked at the first 1807 * keep-state or check-state occurrence, 1808 * with the result being stored in dyn_dir. 1809 * The compiler introduces a PROBE_STATE 1810 * instruction for us when we have a 1811 * KEEP_STATE (because PROBE_STATE needs 1812 * to be run first). 1813 */ 1814 if (dyn_dir == MATCH_UNKNOWN && 1815 (q = lookup_dyn_rule(&args->f_id, 1816 &dyn_dir, proto == IPPROTO_TCP ? 1817 L3HDR(struct tcphdr, ip) : NULL)) 1818 != NULL) { 1819 /* 1820 * Found dynamic entry, update stats 1821 * and jump to the 'action' part of 1822 * the parent rule. 1823 */ 1824 q->pcnt++; 1825 q->bcnt += ip_len; 1826 f = q->rule; 1827 cmd = ACTION_PTR(f); 1828 l = f->cmd_len - f->act_ofs; 1829 goto check_body; 1830 } 1831 /* 1832 * Dynamic entry not found. If CHECK_STATE, 1833 * skip to next rule, if PROBE_STATE just 1834 * ignore and continue with next opcode. 1835 */ 1836 if (cmd->opcode == O_CHECK_STATE) 1837 goto next_rule; 1838 match = 1; 1839 break; 1840 1841 case O_ACCEPT: 1842 retval = 0; /* accept */ 1843 goto done; 1844 1845 case O_PIPE: 1846 case O_QUEUE: 1847 args->rule = f; /* report matching rule */ 1848 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 1849 goto done; 1850 1851 case O_DIVERT: 1852 case O_TEE: 1853 if (args->eh) /* not on layer 2 */ 1854 break; 1855 args->divert_rule = f->rulenum; 1856 retval = (cmd->opcode == O_DIVERT) ? 1857 cmd->arg1 : 1858 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 1859 goto done; 1860 1861 case O_COUNT: 1862 case O_SKIPTO: 1863 f->pcnt++; /* update stats */ 1864 f->bcnt += ip_len; 1865 f->timestamp = time_second; 1866 if (cmd->opcode == O_COUNT) 1867 goto next_rule; 1868 /* handle skipto */ 1869 if (f->next_rule == NULL) 1870 lookup_next_rule(f); 1871 f = f->next_rule; 1872 goto again; 1873 1874 case O_REJECT: 1875 /* 1876 * Drop the packet and send a reject notice 1877 * if the packet is not ICMP (or is an ICMP 1878 * query), and it is not multicast/broadcast. 1879 */ 1880 if (hlen > 0 && 1881 (proto != IPPROTO_ICMP || 1882 is_icmp_query(ip)) && 1883 !(m->m_flags & (M_BCAST|M_MCAST)) && 1884 !IN_MULTICAST(dst_ip.s_addr)) { 1885 send_reject(args, cmd->arg1, 1886 offset,ip_len); 1887 m = args->m; 1888 } 1889 /* FALLTHROUGH */ 1890 case O_DENY: 1891 retval = IP_FW_PORT_DENY_FLAG; 1892 goto done; 1893 1894 case O_FORWARD_IP: 1895 if (args->eh) /* not valid on layer2 pkts */ 1896 break; 1897 if (!q || dyn_dir == MATCH_FORWARD) 1898 args->next_hop = 1899 &((ipfw_insn_sa *)cmd)->sa; 1900 retval = 0; 1901 goto done; 1902 1903 default: 1904 panic("-- unknown opcode %d\n", cmd->opcode); 1905 } /* end of switch() on opcodes */ 1906 1907 if (cmd->len & F_NOT) 1908 match = !match; 1909 1910 if (match) { 1911 if (cmd->len & F_OR) 1912 skip_or = 1; 1913 } else { 1914 if (!(cmd->len & F_OR)) /* not an OR block, */ 1915 break; /* try next rule */ 1916 } 1917 1918 } /* end of inner for, scan opcodes */ 1919 1920 next_rule:; /* try next rule */ 1921 1922 } /* end of outer for, scan rules */ 1923 printf("+++ ipfw: ouch!, skip past end of rules, denying packet\n"); 1924 return(IP_FW_PORT_DENY_FLAG); 1925 1926 done: 1927 /* Update statistics */ 1928 f->pcnt++; 1929 f->bcnt += ip_len; 1930 f->timestamp = time_second; 1931 return retval; 1932 1933 pullup_failed: 1934 if (fw_verbose) 1935 printf("pullup failed\n"); 1936 return(IP_FW_PORT_DENY_FLAG); 1937 } 1938 1939 /* 1940 * When a rule is added/deleted, clear the next_rule pointers in all rules. 1941 * These will be reconstructed on the fly as packets are matched. 1942 * Must be called at splimp(). 1943 */ 1944 static void 1945 flush_rule_ptrs(void) 1946 { 1947 struct ip_fw *rule; 1948 1949 for (rule = layer3_chain; rule; rule = rule->next) 1950 rule->next_rule = NULL; 1951 } 1952 1953 /* 1954 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 1955 * pipe/queue, or to all of them (match == NULL). 1956 * Must be called at splimp(). 1957 */ 1958 void 1959 flush_pipe_ptrs(struct dn_flow_set *match) 1960 { 1961 struct ip_fw *rule; 1962 1963 for (rule = layer3_chain; rule; rule = rule->next) { 1964 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 1965 1966 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 1967 continue; 1968 if (match == NULL || cmd->pipe_ptr == match) 1969 cmd->pipe_ptr = NULL; 1970 } 1971 } 1972 1973 /* 1974 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 1975 * possibly create a rule number and add the rule to the list. 1976 * Update the rule_number in the input struct so the caller knows it as well. 1977 */ 1978 static int 1979 add_rule(struct ip_fw **head, struct ip_fw *input_rule) 1980 { 1981 struct ip_fw *rule, *f, *prev; 1982 int s; 1983 int l = RULESIZE(input_rule); 1984 1985 if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 1986 return (EINVAL); 1987 1988 rule = malloc(l, M_IPFW, M_NOWAIT | M_ZERO); 1989 if (rule == NULL) 1990 return (ENOSPC); 1991 1992 bcopy(input_rule, rule, l); 1993 1994 rule->next = NULL; 1995 rule->next_rule = NULL; 1996 1997 rule->pcnt = 0; 1998 rule->bcnt = 0; 1999 rule->timestamp = 0; 2000 2001 s = splimp(); 2002 2003 if (*head == NULL) { /* default rule */ 2004 *head = rule; 2005 goto done; 2006 } 2007 2008 /* 2009 * If rulenum is 0, find highest numbered rule before the 2010 * default rule, and add autoinc_step 2011 */ 2012 if (autoinc_step < 1) 2013 autoinc_step = 1; 2014 else if (autoinc_step > 1000) 2015 autoinc_step = 1000; 2016 if (rule->rulenum == 0) { 2017 /* 2018 * locate the highest numbered rule before default 2019 */ 2020 for (f = *head; f; f = f->next) { 2021 if (f->rulenum == IPFW_DEFAULT_RULE) 2022 break; 2023 rule->rulenum = f->rulenum; 2024 } 2025 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2026 rule->rulenum += autoinc_step; 2027 input_rule->rulenum = rule->rulenum; 2028 } 2029 2030 /* 2031 * Now insert the new rule in the right place in the sorted list. 2032 */ 2033 for (prev = NULL, f = *head; f; prev = f, f = f->next) { 2034 if (f->rulenum > rule->rulenum) { /* found the location */ 2035 if (prev) { 2036 rule->next = f; 2037 prev->next = rule; 2038 } else { /* head insert */ 2039 rule->next = *head; 2040 *head = rule; 2041 } 2042 break; 2043 } 2044 } 2045 flush_rule_ptrs(); 2046 done: 2047 static_count++; 2048 static_len += l; 2049 splx(s); 2050 DEB(printf("++ installed rule %d, static count now %d\n", 2051 rule->rulenum, static_count);) 2052 return (0); 2053 } 2054 2055 /** 2056 * Free storage associated with a static rule (including derived 2057 * dynamic rules). 2058 * The caller is in charge of clearing rule pointers to avoid 2059 * dangling pointers. 2060 * @return a pointer to the next entry. 2061 * Arguments are not checked, so they better be correct. 2062 * Must be called at splimp(). 2063 */ 2064 static struct ip_fw * 2065 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) 2066 { 2067 struct ip_fw *n; 2068 int l = RULESIZE(rule); 2069 2070 n = rule->next; 2071 remove_dyn_rule(rule, NULL /* force removal */); 2072 if (prev == NULL) 2073 *head = n; 2074 else 2075 prev->next = n; 2076 static_count--; 2077 static_len -= l; 2078 2079 if (DUMMYNET_LOADED) 2080 ip_dn_ruledel_ptr(rule); 2081 free(rule, M_IPFW); 2082 return n; 2083 } 2084 2085 /* 2086 * Deletes all rules from a chain (including the default rule 2087 * if the second argument is set). 2088 * Must be called at splimp(). 2089 */ 2090 static void 2091 free_chain(struct ip_fw **chain, int kill_default) 2092 { 2093 struct ip_fw *rule; 2094 2095 flush_rule_ptrs(); /* more efficient to do outside the loop */ 2096 2097 while ( (rule = *chain) != NULL && 2098 (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) 2099 delete_rule(chain, NULL, rule); 2100 } 2101 2102 /** 2103 * Remove all rules with given number, and also do set manipulation. 2104 * 2105 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2106 * the next 8 bits are the new set, the top 8 bits are the command: 2107 * 2108 * 0 delete rules with given number 2109 * 1 delete rules with given set number 2110 * 2 move rules with given number to new set 2111 * 3 move rules with given set number to new set 2112 * 4 swap sets with given numbers 2113 */ 2114 static int 2115 del_entry(struct ip_fw **chain, u_int32_t arg) 2116 { 2117 struct ip_fw *prev, *rule; 2118 int s; 2119 u_int16_t rulenum; 2120 u_int8_t cmd, new_set; 2121 2122 rulenum = arg & 0xffff; 2123 cmd = (arg >> 24) & 0xff; 2124 new_set = (arg >> 16) & 0xff; 2125 2126 if (cmd > 4) 2127 return EINVAL; 2128 if (new_set > 30) 2129 return EINVAL; 2130 if (cmd == 0 || cmd == 2) { 2131 if (rulenum == IPFW_DEFAULT_RULE) 2132 return EINVAL; 2133 } else { 2134 if (rulenum > 30) 2135 return EINVAL; 2136 } 2137 2138 switch (cmd) { 2139 case 0: /* delete rules with given number */ 2140 /* 2141 * locate first rule to delete 2142 */ 2143 for (prev = NULL, rule = *chain; 2144 rule && rule->rulenum < rulenum; 2145 prev = rule, rule = rule->next) 2146 ; 2147 if (rule->rulenum != rulenum) 2148 return EINVAL; 2149 2150 s = splimp(); /* no access to rules while removing */ 2151 /* 2152 * flush pointers outside the loop, then delete all matching 2153 * rules. prev remains the same throughout the cycle. 2154 */ 2155 flush_rule_ptrs(); 2156 while (rule && rule->rulenum == rulenum) 2157 rule = delete_rule(chain, prev, rule); 2158 splx(s); 2159 break; 2160 2161 case 1: /* delete all rules with given set number */ 2162 s = splimp(); 2163 flush_rule_ptrs(); 2164 for (prev = NULL, rule = *chain; rule ; ) 2165 if (rule->set == rulenum) 2166 rule = delete_rule(chain, prev, rule); 2167 else { 2168 prev = rule; 2169 rule = rule->next; 2170 } 2171 splx(s); 2172 break; 2173 2174 case 2: /* move rules with given number to new set */ 2175 s = splimp(); 2176 for (rule = *chain; rule ; rule = rule->next) 2177 if (rule->rulenum == rulenum) 2178 rule->set = new_set; 2179 splx(s); 2180 break; 2181 2182 case 3: /* move rules with given set number to new set */ 2183 s = splimp(); 2184 for (rule = *chain; rule ; rule = rule->next) 2185 if (rule->set == rulenum) 2186 rule->set = new_set; 2187 splx(s); 2188 break; 2189 2190 case 4: /* swap two sets */ 2191 s = splimp(); 2192 for (rule = *chain; rule ; rule = rule->next) 2193 if (rule->set == rulenum) 2194 rule->set = new_set; 2195 else if (rule->set == new_set) 2196 rule->set = rulenum; 2197 splx(s); 2198 break; 2199 } 2200 return 0; 2201 } 2202 2203 /* 2204 * Clear counters for a specific rule. 2205 */ 2206 static void 2207 clear_counters(struct ip_fw *rule, int log_only) 2208 { 2209 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2210 2211 if (log_only == 0) { 2212 rule->bcnt = rule->pcnt = 0; 2213 rule->timestamp = 0; 2214 } 2215 if (l->o.opcode == O_LOG) 2216 l->log_left = l->max_log; 2217 } 2218 2219 /** 2220 * Reset some or all counters on firewall rules. 2221 * @arg frwl is null to clear all entries, or contains a specific 2222 * rule number. 2223 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2224 */ 2225 static int 2226 zero_entry(int rulenum, int log_only) 2227 { 2228 struct ip_fw *rule; 2229 int s; 2230 char *msg; 2231 2232 if (rulenum == 0) { 2233 s = splimp(); 2234 norule_counter = 0; 2235 for (rule = layer3_chain; rule; rule = rule->next) 2236 clear_counters(rule, log_only); 2237 splx(s); 2238 msg = log_only ? "ipfw: All logging counts reset.\n" : 2239 "ipfw: Accounting cleared.\n"; 2240 } else { 2241 int cleared = 0; 2242 /* 2243 * We can have multiple rules with the same number, so we 2244 * need to clear them all. 2245 */ 2246 for (rule = layer3_chain; rule; rule = rule->next) 2247 if (rule->rulenum == rulenum) { 2248 s = splimp(); 2249 while (rule && rule->rulenum == rulenum) { 2250 clear_counters(rule, log_only); 2251 rule = rule->next; 2252 } 2253 splx(s); 2254 cleared = 1; 2255 break; 2256 } 2257 if (!cleared) /* we did not find any matching rules */ 2258 return (EINVAL); 2259 msg = log_only ? "ipfw: Entry %d logging count reset.\n" : 2260 "ipfw: Entry %d cleared.\n"; 2261 } 2262 if (fw_verbose) 2263 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); 2264 return (0); 2265 } 2266 2267 /* 2268 * Check validity of the structure before insert. 2269 * Fortunately rules are simple, so this mostly need to check rule sizes. 2270 */ 2271 static int 2272 check_ipfw_struct(struct ip_fw *rule, int size) 2273 { 2274 int l, cmdlen = 0; 2275 int have_action=0; 2276 ipfw_insn *cmd; 2277 2278 if (size < sizeof(*rule)) { 2279 printf("ipfw: rule too short\n"); 2280 return (EINVAL); 2281 } 2282 /* first, check for valid size */ 2283 l = RULESIZE(rule); 2284 if (l != size) { 2285 printf("ipfw: size mismatch (have %d want %d)\n", size, l); 2286 return (EINVAL); 2287 } 2288 /* 2289 * Now go for the individual checks. Very simple ones, basically only 2290 * instruction sizes. 2291 */ 2292 for (l = rule->cmd_len, cmd = rule->cmd ; 2293 l > 0 ; l -= cmdlen, cmd += cmdlen) { 2294 cmdlen = F_LEN(cmd); 2295 if (cmdlen > l) { 2296 printf("ipfw: opcode %d size truncated\n", 2297 cmd->opcode); 2298 return EINVAL; 2299 } 2300 DEB(printf("ipfw: opcode %d\n", cmd->opcode);) 2301 switch (cmd->opcode) { 2302 case O_NOP: 2303 case O_PROBE_STATE: 2304 case O_KEEP_STATE: 2305 case O_PROTO: 2306 case O_IP_SRC_ME: 2307 case O_IP_DST_ME: 2308 case O_LAYER2: 2309 case O_IN: 2310 case O_FRAG: 2311 case O_IPOPT: 2312 case O_IPLEN: 2313 case O_IPID: 2314 case O_IPTOS: 2315 case O_IPPRECEDENCE: 2316 case O_IPTTL: 2317 case O_IPVER: 2318 case O_TCPWIN: 2319 case O_TCPFLAGS: 2320 case O_TCPOPTS: 2321 case O_ESTAB: 2322 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2323 goto bad_size; 2324 break; 2325 2326 case O_UID: 2327 case O_GID: 2328 case O_IP_SRC: 2329 case O_IP_DST: 2330 case O_TCPSEQ: 2331 case O_TCPACK: 2332 case O_PROB: 2333 case O_ICMPTYPE: 2334 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) 2335 goto bad_size; 2336 break; 2337 2338 case O_LIMIT: 2339 if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) 2340 goto bad_size; 2341 break; 2342 2343 case O_LOG: 2344 if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) 2345 goto bad_size; 2346 2347 ((ipfw_insn_log *)cmd)->log_left = 2348 ((ipfw_insn_log *)cmd)->max_log; 2349 2350 break; 2351 2352 case O_IP_SRC_MASK: 2353 case O_IP_DST_MASK: 2354 if (cmdlen != F_INSN_SIZE(ipfw_insn_ip)) 2355 goto bad_size; 2356 if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) { 2357 printf("ipfw: opcode %d, useless rule\n", 2358 cmd->opcode); 2359 return EINVAL; 2360 } 2361 break; 2362 2363 case O_IP_SRC_SET: 2364 case O_IP_DST_SET: 2365 if (cmd->arg1 == 0 || cmd->arg1 > 256) { 2366 printf("ipfw: invalid set size %d\n", 2367 cmd->arg1); 2368 return EINVAL; 2369 } 2370 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + 2371 (cmd->arg1+31)/32 ) 2372 goto bad_size; 2373 break; 2374 2375 case O_MACADDR2: 2376 if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) 2377 goto bad_size; 2378 break; 2379 2380 case O_MAC_TYPE: 2381 case O_IP_SRCPORT: 2382 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ 2383 if (cmdlen < 2 || cmdlen > 31) 2384 goto bad_size; 2385 break; 2386 2387 case O_RECV: 2388 case O_XMIT: 2389 case O_VIA: 2390 if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) 2391 goto bad_size; 2392 break; 2393 2394 case O_PIPE: 2395 case O_QUEUE: 2396 if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) 2397 goto bad_size; 2398 goto check_action; 2399 2400 case O_FORWARD_IP: 2401 if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) 2402 goto bad_size; 2403 goto check_action; 2404 2405 case O_FORWARD_MAC: /* XXX not implemented yet */ 2406 case O_CHECK_STATE: 2407 case O_COUNT: 2408 case O_ACCEPT: 2409 case O_DENY: 2410 case O_REJECT: 2411 case O_SKIPTO: 2412 case O_DIVERT: 2413 case O_TEE: 2414 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2415 goto bad_size; 2416 check_action: 2417 if (have_action) { 2418 printf("ipfw: opcode %d, multiple actions" 2419 " not allowed\n", 2420 cmd->opcode); 2421 return EINVAL; 2422 } 2423 have_action = 1; 2424 if (l != cmdlen) { 2425 printf("ipfw: opcode %d, action must be" 2426 " last opcode\n", 2427 cmd->opcode); 2428 return EINVAL; 2429 } 2430 break; 2431 default: 2432 printf("ipfw: opcode %d, unknown opcode\n", 2433 cmd->opcode); 2434 return EINVAL; 2435 } 2436 } 2437 if (have_action == 0) { 2438 printf("ipfw: missing action\n"); 2439 return EINVAL; 2440 } 2441 return 0; 2442 2443 bad_size: 2444 printf("ipfw: opcode %d size %d wrong\n", 2445 cmd->opcode, cmdlen); 2446 return EINVAL; 2447 } 2448 2449 2450 /** 2451 * {set|get}sockopt parser. 2452 */ 2453 static int 2454 ipfw_ctl(struct sockopt *sopt) 2455 { 2456 int error, s, rulenum; 2457 size_t size; 2458 struct ip_fw *bp , *buf, *rule; 2459 2460 static u_int32_t rule_buf[255]; /* we copy the data here */ 2461 2462 /* 2463 * Disallow modifications in really-really secure mode, but still allow 2464 * the logging counters to be reset. 2465 */ 2466 if (sopt->sopt_name == IP_FW_ADD || 2467 (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { 2468 #if __FreeBSD_version >= 500034 2469 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); 2470 if (error) 2471 return (error); 2472 #else /* FreeBSD 4.x */ 2473 if (securelevel >= 3) 2474 return (EPERM); 2475 #endif 2476 } 2477 2478 error = 0; 2479 2480 switch (sopt->sopt_name) { 2481 case IP_FW_GET: 2482 /* 2483 * pass up a copy of the current rules. Static rules 2484 * come first (the last of which has number IPFW_DEFAULT_RULE), 2485 * followed by a possibly empty list of dynamic rule. 2486 * The last dynamic rule has NULL in the "next" field. 2487 */ 2488 s = splimp(); 2489 size = static_len; /* size of static rules */ 2490 if (ipfw_dyn_v) /* add size of dyn.rules */ 2491 size += (dyn_count * sizeof(ipfw_dyn_rule)); 2492 2493 /* 2494 * XXX todo: if the user passes a short length just to know 2495 * how much room is needed, do not bother filling up the 2496 * buffer, just jump to the sooptcopyout. 2497 */ 2498 buf = malloc(size, M_TEMP, M_WAITOK); 2499 if (buf == 0) { 2500 splx(s); 2501 error = ENOBUFS; 2502 break; 2503 } 2504 2505 bp = buf; 2506 for (rule = layer3_chain; rule ; rule = rule->next) { 2507 int i = RULESIZE(rule); 2508 bcopy(rule, bp, i); 2509 /* 2510 * abuse 'next_rule' to store the set_disable word 2511 */ 2512 (u_int32_t)(((struct ip_fw *)bp)->next_rule) = 2513 set_disable; 2514 bp = (struct ip_fw *)((char *)bp + i); 2515 } 2516 if (ipfw_dyn_v) { 2517 int i; 2518 ipfw_dyn_rule *p, *dst, *last = NULL; 2519 2520 dst = (ipfw_dyn_rule *)bp; 2521 for (i = 0 ; i < curr_dyn_buckets ; i++ ) 2522 for ( p = ipfw_dyn_v[i] ; p != NULL ; 2523 p = p->next, dst++ ) { 2524 bcopy(p, dst, sizeof *p); 2525 (int)dst->rule = p->rule->rulenum ; 2526 /* 2527 * store a non-null value in "next". 2528 * The userland code will interpret a 2529 * NULL here as a marker 2530 * for the last dynamic rule. 2531 */ 2532 dst->next = dst ; 2533 last = dst ; 2534 dst->expire = 2535 TIME_LEQ(dst->expire, time_second) ? 2536 0 : dst->expire - time_second ; 2537 } 2538 if (last != NULL) /* mark last dynamic rule */ 2539 last->next = NULL; 2540 } 2541 splx(s); 2542 2543 error = sooptcopyout(sopt, buf, size); 2544 free(buf, M_TEMP); 2545 break; 2546 2547 case IP_FW_FLUSH: 2548 /* 2549 * Normally we cannot release the lock on each iteration. 2550 * We could do it here only because we start from the head all 2551 * the times so there is no risk of missing some entries. 2552 * On the other hand, the risk is that we end up with 2553 * a very inconsistent ruleset, so better keep the lock 2554 * around the whole cycle. 2555 * 2556 * XXX this code can be improved by resetting the head of 2557 * the list to point to the default rule, and then freeing 2558 * the old list without the need for a lock. 2559 */ 2560 2561 s = splimp(); 2562 free_chain(&layer3_chain, 0 /* keep default rule */); 2563 splx(s); 2564 break; 2565 2566 case IP_FW_ADD: 2567 rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ 2568 error = sooptcopyin(sopt, rule, sizeof(rule_buf), 2569 sizeof(struct ip_fw) ); 2570 size = sopt->sopt_valsize; 2571 if (error || (error = check_ipfw_struct(rule, size))) 2572 break; 2573 2574 error = add_rule(&layer3_chain, rule); 2575 size = RULESIZE(rule); 2576 if (!error && sopt->sopt_dir == SOPT_GET) 2577 error = sooptcopyout(sopt, rule, size); 2578 break; 2579 2580 case IP_FW_DEL: 2581 /* 2582 * IP_FW_DEL is used for deleting single rules or sets, 2583 * and (ab)used to atomically manipulate sets. Argument size 2584 * is used to distinguish between the two: 2585 * sizeof(u_int32_t) 2586 * delete single rule or set of rules, 2587 * or reassign rules (or sets) to a different set. 2588 * 2*sizeof(u_int32_t) 2589 * atomic disable/enable sets. 2590 * first u_int32_t contains sets to be disabled, 2591 * second u_int32_t contains sets to be enabled. 2592 */ 2593 error = sooptcopyin(sopt, rule_buf, 2594 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2595 if (error) 2596 break; 2597 size = sopt->sopt_valsize; 2598 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2599 error = del_entry(&layer3_chain, rule_buf[0]); 2600 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2601 set_disable = 2602 (set_disable | rule_buf[0]) & ~rule_buf[1] & 2603 ~(1<<31); /* set 31 always enabled */ 2604 else 2605 error = EINVAL; 2606 break; 2607 2608 case IP_FW_ZERO: 2609 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2610 rulenum=0; 2611 2612 if (sopt->sopt_val != 0) { 2613 error = sooptcopyin(sopt, &rulenum, 2614 sizeof(int), sizeof(int)); 2615 if (error) 2616 break; 2617 } 2618 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); 2619 break; 2620 2621 default: 2622 printf("ipfw_ctl invalid option %d\n", sopt->sopt_name); 2623 error = EINVAL; 2624 } 2625 2626 return (error); 2627 } 2628 2629 /** 2630 * dummynet needs a reference to the default rule, because rules can be 2631 * deleted while packets hold a reference to them. When this happens, 2632 * dummynet changes the reference to the default rule (it could well be a 2633 * NULL pointer, but this way we do not need to check for the special 2634 * case, plus here he have info on the default behaviour). 2635 */ 2636 struct ip_fw *ip_fw_default_rule; 2637 2638 /* 2639 * This procedure is only used to handle keepalives. It is invoked 2640 * every dyn_keepalive_period 2641 */ 2642 static void 2643 ipfw_tick(void * __unused unused) 2644 { 2645 int i; 2646 int s; 2647 ipfw_dyn_rule *q; 2648 2649 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2650 goto done; 2651 2652 s = splimp(); 2653 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2654 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2655 if (q->dyn_type == O_LIMIT_PARENT) 2656 continue; 2657 if (q->id.proto != IPPROTO_TCP) 2658 continue; 2659 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2660 continue; 2661 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2662 q->expire)) 2663 continue; /* too early */ 2664 if (TIME_LEQ(q->expire, time_second)) 2665 continue; /* too late, rule expired */ 2666 2667 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2668 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2669 } 2670 } 2671 splx(s); 2672 done: 2673 ipfw_timeout_h = timeout(ipfw_tick, NULL, dyn_keepalive_period*hz); 2674 } 2675 2676 static void 2677 ipfw_init(void) 2678 { 2679 struct ip_fw default_rule; 2680 2681 ip_fw_chk_ptr = ipfw_chk; 2682 ip_fw_ctl_ptr = ipfw_ctl; 2683 layer3_chain = NULL; 2684 2685 bzero(&default_rule, sizeof default_rule); 2686 2687 default_rule.act_ofs = 0; 2688 default_rule.rulenum = IPFW_DEFAULT_RULE; 2689 default_rule.cmd_len = 1; 2690 default_rule.set = 31; 2691 2692 default_rule.cmd[0].len = 1; 2693 default_rule.cmd[0].opcode = 2694 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2695 1 ? O_ACCEPT : 2696 #endif 2697 O_DENY; 2698 2699 add_rule(&layer3_chain, &default_rule); 2700 2701 ip_fw_default_rule = layer3_chain; 2702 printf("ipfw2 initialized, divert %s, " 2703 "rule-based forwarding enabled, default to %s, logging ", 2704 #ifdef IPDIVERT 2705 "enabled", 2706 #else 2707 "disabled", 2708 #endif 2709 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2710 2711 #ifdef IPFIREWALL_VERBOSE 2712 fw_verbose = 1; 2713 #endif 2714 #ifdef IPFIREWALL_VERBOSE_LIMIT 2715 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2716 #endif 2717 if (fw_verbose == 0) 2718 printf("disabled\n"); 2719 else if (verbose_limit == 0) 2720 printf("unlimited\n"); 2721 else 2722 printf("limited to %d packets/entry by default\n", 2723 verbose_limit); 2724 bzero(&ipfw_timeout_h, sizeof(struct callout_handle)); 2725 ipfw_timeout_h = timeout(ipfw_tick, NULL, hz); 2726 } 2727 2728 static int 2729 ipfw_modevent(module_t mod, int type, void *unused) 2730 { 2731 int s; 2732 int err = 0; 2733 2734 switch (type) { 2735 case MOD_LOAD: 2736 s = splimp(); 2737 if (IPFW_LOADED) { 2738 splx(s); 2739 printf("IP firewall already loaded\n"); 2740 err = EEXIST; 2741 } else { 2742 ipfw_init(); 2743 splx(s); 2744 } 2745 break; 2746 2747 case MOD_UNLOAD: 2748 #if !defined(KLD_MODULE) 2749 printf("ipfw statically compiled, cannot unload\n"); 2750 err = EBUSY; 2751 #else 2752 s = splimp(); 2753 untimeout(ipfw_tick, NULL, ipfw_timeout_h); 2754 ip_fw_chk_ptr = NULL; 2755 ip_fw_ctl_ptr = NULL; 2756 free_chain(&layer3_chain, 1 /* kill default rule */); 2757 splx(s); 2758 printf("IP firewall unloaded\n"); 2759 #endif 2760 break; 2761 default: 2762 break; 2763 } 2764 return err; 2765 } 2766 2767 static moduledata_t ipfwmod = { 2768 "ipfw", 2769 ipfw_modevent, 2770 0 2771 }; 2772 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); 2773 MODULE_VERSION(ipfw, 1); 2774 #endif /* IPFW2 */ 2775