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 1.26 2006/12/22 23:44:57 swildner 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/thread2.h> 58 #include <sys/ucred.h> 59 #include <sys/in_cksum.h> 60 #include <net/if.h> 61 #include <net/route.h> 62 #include <netinet/in.h> 63 #include <netinet/in_systm.h> 64 #include <netinet/in_var.h> 65 #include <netinet/in_pcb.h> 66 #include <netinet/ip.h> 67 #include <netinet/ip_var.h> 68 #include <netinet/ip_icmp.h> 69 #include "ip_fw.h" 70 #include <net/dummynet/ip_dummynet.h> 71 #include <netinet/tcp.h> 72 #include <netinet/tcp_timer.h> 73 #include <netinet/tcp_var.h> 74 #include <netinet/tcpip.h> 75 #include <netinet/udp.h> 76 #include <netinet/udp_var.h> 77 78 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */ 79 80 /* 81 * set_disable contains one bit per set value (0..31). 82 * If the bit is set, all rules with the corresponding set 83 * are disabled. Set 31 is reserved for the default rule 84 * and CANNOT be disabled. 85 */ 86 static u_int32_t set_disable; 87 88 static int fw_verbose; 89 static int verbose_limit; 90 91 static struct callout ipfw_timeout_h; 92 #define IPFW_DEFAULT_RULE 65535 93 94 /* 95 * list of rules for layer 3 96 */ 97 static struct ip_fw *layer3_chain; 98 99 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 100 101 static int fw_debug = 1; 102 static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 103 104 #ifdef SYSCTL_NODE 105 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 106 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, 107 &fw_enable, 0, "Enable ipfw"); 108 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 109 &autoinc_step, 0, "Rule number autincrement step"); 110 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, 111 &fw_one_pass, 0, 112 "Only do a single pass through ipfw when using dummynet(4)"); 113 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 114 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 115 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, 116 &fw_verbose, 0, "Log matches to ipfw rules"); 117 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 118 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 119 120 /* 121 * Description of dynamic rules. 122 * 123 * Dynamic rules are stored in lists accessed through a hash table 124 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 125 * be modified through the sysctl variable dyn_buckets which is 126 * updated when the table becomes empty. 127 * 128 * XXX currently there is only one list, ipfw_dyn. 129 * 130 * When a packet is received, its address fields are first masked 131 * with the mask defined for the rule, then hashed, then matched 132 * against the entries in the corresponding list. 133 * Dynamic rules can be used for different purposes: 134 * + stateful rules; 135 * + enforcing limits on the number of sessions; 136 * + in-kernel NAT (not implemented yet) 137 * 138 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 139 * measured in seconds and depending on the flags. 140 * 141 * The total number of dynamic rules is stored in dyn_count. 142 * The max number of dynamic rules is dyn_max. When we reach 143 * the maximum number of rules we do not create anymore. This is 144 * done to avoid consuming too much memory, but also too much 145 * time when searching on each packet (ideally, we should try instead 146 * to put a limit on the length of the list on each bucket...). 147 * 148 * Each dynamic rule holds a pointer to the parent ipfw rule so 149 * we know what action to perform. Dynamic rules are removed when 150 * the parent rule is deleted. XXX we should make them survive. 151 * 152 * There are some limitations with dynamic rules -- we do not 153 * obey the 'randomized match', and we do not do multiple 154 * passes through the firewall. XXX check the latter!!! 155 */ 156 static ipfw_dyn_rule **ipfw_dyn_v = NULL; 157 static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 158 static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 159 160 /* 161 * Timeouts for various events in handing dynamic rules. 162 */ 163 static u_int32_t dyn_ack_lifetime = 300; 164 static u_int32_t dyn_syn_lifetime = 20; 165 static u_int32_t dyn_fin_lifetime = 1; 166 static u_int32_t dyn_rst_lifetime = 1; 167 static u_int32_t dyn_udp_lifetime = 10; 168 static u_int32_t dyn_short_lifetime = 5; 169 170 /* 171 * Keepalives are sent if dyn_keepalive is set. They are sent every 172 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 173 * seconds of lifetime of a rule. 174 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 175 * than dyn_keepalive_period. 176 */ 177 178 static u_int32_t dyn_keepalive_interval = 20; 179 static u_int32_t dyn_keepalive_period = 5; 180 static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 181 182 static u_int32_t static_count; /* # of static rules */ 183 static u_int32_t static_len; /* size in bytes of static rules */ 184 static u_int32_t dyn_count; /* # of dynamic rules */ 185 static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 186 187 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 188 &dyn_buckets, 0, "Number of dyn. buckets"); 189 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 190 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 191 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 192 &dyn_count, 0, "Number of dyn. rules"); 193 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 194 &dyn_max, 0, "Max number of dyn. rules"); 195 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 196 &static_count, 0, "Number of static rules"); 197 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 198 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 199 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 200 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 201 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 202 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 203 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 204 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 205 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 206 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 207 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 208 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 209 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 210 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 211 212 #endif /* SYSCTL_NODE */ 213 214 215 static ip_fw_chk_t ipfw_chk; 216 217 ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 218 219 /* 220 * This macro maps an ip pointer into a layer3 header pointer of type T 221 */ 222 #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 223 224 static __inline int 225 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 226 { 227 int type = L3HDR(struct icmp,ip)->icmp_type; 228 229 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 230 } 231 232 #define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 233 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 234 235 static int 236 is_icmp_query(struct ip *ip) 237 { 238 int type = L3HDR(struct icmp, ip)->icmp_type; 239 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 240 } 241 #undef TT 242 243 /* 244 * The following checks use two arrays of 8 or 16 bits to store the 245 * bits that we want set or clear, respectively. They are in the 246 * low and high half of cmd->arg1 or cmd->d[0]. 247 * 248 * We scan options and store the bits we find set. We succeed if 249 * 250 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 251 * 252 * The code is sometimes optimized not to store additional variables. 253 */ 254 255 static int 256 flags_match(ipfw_insn *cmd, u_int8_t bits) 257 { 258 u_char want_clear; 259 bits = ~bits; 260 261 if ( ((cmd->arg1 & 0xff) & bits) != 0) 262 return 0; /* some bits we want set were clear */ 263 want_clear = (cmd->arg1 >> 8) & 0xff; 264 if ( (want_clear & bits) != want_clear) 265 return 0; /* some bits we want clear were set */ 266 return 1; 267 } 268 269 static int 270 ipopts_match(struct ip *ip, ipfw_insn *cmd) 271 { 272 int optlen, bits = 0; 273 u_char *cp = (u_char *)(ip + 1); 274 int x = (ip->ip_hl << 2) - sizeof (struct ip); 275 276 for (; x > 0; x -= optlen, cp += optlen) { 277 int opt = cp[IPOPT_OPTVAL]; 278 279 if (opt == IPOPT_EOL) 280 break; 281 if (opt == IPOPT_NOP) 282 optlen = 1; 283 else { 284 optlen = cp[IPOPT_OLEN]; 285 if (optlen <= 0 || optlen > x) 286 return 0; /* invalid or truncated */ 287 } 288 switch (opt) { 289 290 default: 291 break; 292 293 case IPOPT_LSRR: 294 bits |= IP_FW_IPOPT_LSRR; 295 break; 296 297 case IPOPT_SSRR: 298 bits |= IP_FW_IPOPT_SSRR; 299 break; 300 301 case IPOPT_RR: 302 bits |= IP_FW_IPOPT_RR; 303 break; 304 305 case IPOPT_TS: 306 bits |= IP_FW_IPOPT_TS; 307 break; 308 } 309 } 310 return (flags_match(cmd, bits)); 311 } 312 313 static int 314 tcpopts_match(struct ip *ip, ipfw_insn *cmd) 315 { 316 int optlen, bits = 0; 317 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 318 u_char *cp = (u_char *)(tcp + 1); 319 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 320 321 for (; x > 0; x -= optlen, cp += optlen) { 322 int opt = cp[0]; 323 if (opt == TCPOPT_EOL) 324 break; 325 if (opt == TCPOPT_NOP) 326 optlen = 1; 327 else { 328 optlen = cp[1]; 329 if (optlen <= 0) 330 break; 331 } 332 333 switch (opt) { 334 335 default: 336 break; 337 338 case TCPOPT_MAXSEG: 339 bits |= IP_FW_TCPOPT_MSS; 340 break; 341 342 case TCPOPT_WINDOW: 343 bits |= IP_FW_TCPOPT_WINDOW; 344 break; 345 346 case TCPOPT_SACK_PERMITTED: 347 case TCPOPT_SACK: 348 bits |= IP_FW_TCPOPT_SACK; 349 break; 350 351 case TCPOPT_TIMESTAMP: 352 bits |= IP_FW_TCPOPT_TS; 353 break; 354 355 case TCPOPT_CC: 356 case TCPOPT_CCNEW: 357 case TCPOPT_CCECHO: 358 bits |= IP_FW_TCPOPT_CC; 359 break; 360 } 361 } 362 return (flags_match(cmd, bits)); 363 } 364 365 static int 366 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 367 { 368 if (ifp == NULL) /* no iface with this packet, match fails */ 369 return 0; 370 /* Check by name or by IP address */ 371 if (cmd->name[0] != '\0') { /* match by name */ 372 /* Check name */ 373 if (cmd->p.glob) { 374 if (kfnmatch(cmd->name, ifp->if_xname, 0) == 0) 375 return(1); 376 } else { 377 if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) 378 return(1); 379 } 380 } else { 381 struct ifaddr *ia; 382 383 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 384 if (ia->ifa_addr == NULL) 385 continue; 386 if (ia->ifa_addr->sa_family != AF_INET) 387 continue; 388 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 389 (ia->ifa_addr))->sin_addr.s_addr) 390 return(1); /* match */ 391 } 392 } 393 return(0); /* no match, fail ... */ 394 } 395 396 static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 397 398 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 399 #define SNP(buf) buf, sizeof(buf) 400 401 /* 402 * We enter here when we have a rule with O_LOG. 403 * XXX this function alone takes about 2Kbytes of code! 404 */ 405 static void 406 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 407 struct mbuf *m, struct ifnet *oif) 408 { 409 char *action; 410 int limit_reached = 0; 411 char action2[40], proto[48], fragment[28]; 412 413 fragment[0] = '\0'; 414 proto[0] = '\0'; 415 416 if (f == NULL) { /* bogus pkt */ 417 if (verbose_limit != 0 && norule_counter >= verbose_limit) 418 return; 419 norule_counter++; 420 if (norule_counter == verbose_limit) 421 limit_reached = verbose_limit; 422 action = "Refuse"; 423 } else { /* O_LOG is the first action, find the real one */ 424 ipfw_insn *cmd = ACTION_PTR(f); 425 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 426 427 if (l->max_log != 0 && l->log_left == 0) 428 return; 429 l->log_left--; 430 if (l->log_left == 0) 431 limit_reached = l->max_log; 432 cmd += F_LEN(cmd); /* point to first action */ 433 if (cmd->opcode == O_PROB) 434 cmd += F_LEN(cmd); 435 436 action = action2; 437 switch (cmd->opcode) { 438 case O_DENY: 439 action = "Deny"; 440 break; 441 442 case O_REJECT: 443 if (cmd->arg1==ICMP_REJECT_RST) 444 action = "Reset"; 445 else if (cmd->arg1==ICMP_UNREACH_HOST) 446 action = "Reject"; 447 else 448 ksnprintf(SNPARGS(action2, 0), "Unreach %d", 449 cmd->arg1); 450 break; 451 452 case O_ACCEPT: 453 action = "Accept"; 454 break; 455 case O_COUNT: 456 action = "Count"; 457 break; 458 case O_DIVERT: 459 ksnprintf(SNPARGS(action2, 0), "Divert %d", 460 cmd->arg1); 461 break; 462 case O_TEE: 463 ksnprintf(SNPARGS(action2, 0), "Tee %d", 464 cmd->arg1); 465 break; 466 case O_SKIPTO: 467 ksnprintf(SNPARGS(action2, 0), "SkipTo %d", 468 cmd->arg1); 469 break; 470 case O_PIPE: 471 ksnprintf(SNPARGS(action2, 0), "Pipe %d", 472 cmd->arg1); 473 break; 474 case O_QUEUE: 475 ksnprintf(SNPARGS(action2, 0), "Queue %d", 476 cmd->arg1); 477 break; 478 case O_FORWARD_IP: { 479 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 480 int len; 481 482 len = ksnprintf(SNPARGS(action2, 0), "Forward to %s", 483 inet_ntoa(sa->sa.sin_addr)); 484 if (sa->sa.sin_port) 485 ksnprintf(SNPARGS(action2, len), ":%d", 486 sa->sa.sin_port); 487 } 488 break; 489 default: 490 action = "UNKNOWN"; 491 break; 492 } 493 } 494 495 if (hlen == 0) { /* non-ip */ 496 ksnprintf(SNPARGS(proto, 0), "MAC"); 497 } else { 498 struct ip *ip = mtod(m, struct ip *); 499 /* these three are all aliases to the same thing */ 500 struct icmp *const icmp = L3HDR(struct icmp, ip); 501 struct tcphdr *const tcp = (struct tcphdr *)icmp; 502 struct udphdr *const udp = (struct udphdr *)icmp; 503 504 int ip_off, offset, ip_len; 505 506 int len; 507 508 if (eh != NULL) { /* layer 2 packets are as on the wire */ 509 ip_off = ntohs(ip->ip_off); 510 ip_len = ntohs(ip->ip_len); 511 } else { 512 ip_off = ip->ip_off; 513 ip_len = ip->ip_len; 514 } 515 offset = ip_off & IP_OFFMASK; 516 switch (ip->ip_p) { 517 case IPPROTO_TCP: 518 len = ksnprintf(SNPARGS(proto, 0), "TCP %s", 519 inet_ntoa(ip->ip_src)); 520 if (offset == 0) 521 ksnprintf(SNPARGS(proto, len), ":%d %s:%d", 522 ntohs(tcp->th_sport), 523 inet_ntoa(ip->ip_dst), 524 ntohs(tcp->th_dport)); 525 else 526 ksnprintf(SNPARGS(proto, len), " %s", 527 inet_ntoa(ip->ip_dst)); 528 break; 529 530 case IPPROTO_UDP: 531 len = ksnprintf(SNPARGS(proto, 0), "UDP %s", 532 inet_ntoa(ip->ip_src)); 533 if (offset == 0) 534 ksnprintf(SNPARGS(proto, len), ":%d %s:%d", 535 ntohs(udp->uh_sport), 536 inet_ntoa(ip->ip_dst), 537 ntohs(udp->uh_dport)); 538 else 539 ksnprintf(SNPARGS(proto, len), " %s", 540 inet_ntoa(ip->ip_dst)); 541 break; 542 543 case IPPROTO_ICMP: 544 if (offset == 0) 545 len = ksnprintf(SNPARGS(proto, 0), 546 "ICMP:%u.%u ", 547 icmp->icmp_type, icmp->icmp_code); 548 else 549 len = ksnprintf(SNPARGS(proto, 0), "ICMP "); 550 len += ksnprintf(SNPARGS(proto, len), "%s", 551 inet_ntoa(ip->ip_src)); 552 ksnprintf(SNPARGS(proto, len), " %s", 553 inet_ntoa(ip->ip_dst)); 554 break; 555 556 default: 557 len = ksnprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 558 inet_ntoa(ip->ip_src)); 559 ksnprintf(SNPARGS(proto, len), " %s", 560 inet_ntoa(ip->ip_dst)); 561 break; 562 } 563 564 if (ip_off & (IP_MF | IP_OFFMASK)) 565 ksnprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 566 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 567 offset << 3, 568 (ip_off & IP_MF) ? "+" : ""); 569 } 570 if (oif || m->m_pkthdr.rcvif) 571 log(LOG_SECURITY | LOG_INFO, 572 "ipfw: %d %s %s %s via %s%s\n", 573 f ? f->rulenum : -1, 574 action, proto, oif ? "out" : "in", 575 oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 576 fragment); 577 else 578 log(LOG_SECURITY | LOG_INFO, 579 "ipfw: %d %s %s [no if info]%s\n", 580 f ? f->rulenum : -1, 581 action, proto, fragment); 582 if (limit_reached) 583 log(LOG_SECURITY | LOG_NOTICE, 584 "ipfw: limit %d reached on entry %d\n", 585 limit_reached, f ? f->rulenum : -1); 586 } 587 588 /* 589 * IMPORTANT: the hash function for dynamic rules must be commutative 590 * in source and destination (ip,port), because rules are bidirectional 591 * and we want to find both in the same bucket. 592 */ 593 static __inline int 594 hash_packet(struct ipfw_flow_id *id) 595 { 596 u_int32_t i; 597 598 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 599 i &= (curr_dyn_buckets - 1); 600 return i; 601 } 602 603 /** 604 * unlink a dynamic rule from a chain. prev is a pointer to 605 * the previous one, q is a pointer to the rule to delete, 606 * head is a pointer to the head of the queue. 607 * Modifies q and potentially also head. 608 */ 609 #define UNLINK_DYN_RULE(prev, head, q) { \ 610 ipfw_dyn_rule *old_q = q; \ 611 \ 612 /* remove a refcount to the parent */ \ 613 if (q->dyn_type == O_LIMIT) \ 614 q->parent->count--; \ 615 DEB(kprintf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \ 616 (q->id.src_ip), (q->id.src_port), \ 617 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 618 if (prev != NULL) \ 619 prev->next = q = q->next; \ 620 else \ 621 head = q = q->next; \ 622 dyn_count--; \ 623 kfree(old_q, M_IPFW); } 624 625 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 626 627 /** 628 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 629 * 630 * If keep_me == NULL, rules are deleted even if not expired, 631 * otherwise only expired rules are removed. 632 * 633 * The value of the second parameter is also used to point to identify 634 * a rule we absolutely do not want to remove (e.g. because we are 635 * holding a reference to it -- this is the case with O_LIMIT_PARENT 636 * rules). The pointer is only used for comparison, so any non-null 637 * value will do. 638 */ 639 static void 640 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 641 { 642 static u_int32_t last_remove = 0; 643 644 #define FORCE (keep_me == NULL) 645 646 ipfw_dyn_rule *prev, *q; 647 int i, pass = 0, max_pass = 0; 648 649 if (ipfw_dyn_v == NULL || dyn_count == 0) 650 return; 651 /* do not expire more than once per second, it is useless */ 652 if (!FORCE && last_remove == time_second) 653 return; 654 last_remove = time_second; 655 656 /* 657 * because O_LIMIT refer to parent rules, during the first pass only 658 * remove child and mark any pending LIMIT_PARENT, and remove 659 * them in a second pass. 660 */ 661 next_pass: 662 for (i = 0 ; i < curr_dyn_buckets ; i++) { 663 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 664 /* 665 * Logic can become complex here, so we split tests. 666 */ 667 if (q == keep_me) 668 goto next; 669 if (rule != NULL && rule != q->rule) 670 goto next; /* not the one we are looking for */ 671 if (q->dyn_type == O_LIMIT_PARENT) { 672 /* 673 * handle parent in the second pass, 674 * record we need one. 675 */ 676 max_pass = 1; 677 if (pass == 0) 678 goto next; 679 if (FORCE && q->count != 0 ) { 680 /* XXX should not happen! */ 681 kprintf( "OUCH! cannot remove rule," 682 " count %d\n", q->count); 683 } 684 } else { 685 if (!FORCE && 686 !TIME_LEQ( q->expire, time_second )) 687 goto next; 688 } 689 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 690 continue; 691 next: 692 prev=q; 693 q=q->next; 694 } 695 } 696 if (pass++ < max_pass) 697 goto next_pass; 698 } 699 700 701 /** 702 * lookup a dynamic rule. 703 */ 704 static ipfw_dyn_rule * 705 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 706 struct tcphdr *tcp) 707 { 708 /* 709 * stateful ipfw extensions. 710 * Lookup into dynamic session queue 711 */ 712 #define MATCH_REVERSE 0 713 #define MATCH_FORWARD 1 714 #define MATCH_NONE 2 715 #define MATCH_UNKNOWN 3 716 int i, dir = MATCH_NONE; 717 ipfw_dyn_rule *prev, *q=NULL; 718 719 if (ipfw_dyn_v == NULL) 720 goto done; /* not found */ 721 i = hash_packet( pkt ); 722 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 723 if (q->dyn_type == O_LIMIT_PARENT) 724 goto next; 725 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 726 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 727 continue; 728 } 729 if ( pkt->proto == q->id.proto) { 730 if (pkt->src_ip == q->id.src_ip && 731 pkt->dst_ip == q->id.dst_ip && 732 pkt->src_port == q->id.src_port && 733 pkt->dst_port == q->id.dst_port ) { 734 dir = MATCH_FORWARD; 735 break; 736 } 737 if (pkt->src_ip == q->id.dst_ip && 738 pkt->dst_ip == q->id.src_ip && 739 pkt->src_port == q->id.dst_port && 740 pkt->dst_port == q->id.src_port ) { 741 dir = MATCH_REVERSE; 742 break; 743 } 744 } 745 next: 746 prev = q; 747 q = q->next; 748 } 749 if (q == NULL) 750 goto done; /* q = NULL, not found */ 751 752 if ( prev != NULL) { /* found and not in front */ 753 prev->next = q->next; 754 q->next = ipfw_dyn_v[i]; 755 ipfw_dyn_v[i] = q; 756 } 757 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 758 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 759 760 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 761 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 762 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 763 switch (q->state) { 764 case TH_SYN: /* opening */ 765 q->expire = time_second + dyn_syn_lifetime; 766 break; 767 768 case BOTH_SYN: /* move to established */ 769 case BOTH_SYN | TH_FIN : /* one side tries to close */ 770 case BOTH_SYN | (TH_FIN << 8) : 771 if (tcp) { 772 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 773 u_int32_t ack = ntohl(tcp->th_ack); 774 if (dir == MATCH_FORWARD) { 775 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 776 q->ack_fwd = ack; 777 else { /* ignore out-of-sequence */ 778 break; 779 } 780 } else { 781 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 782 q->ack_rev = ack; 783 else { /* ignore out-of-sequence */ 784 break; 785 } 786 } 787 } 788 q->expire = time_second + dyn_ack_lifetime; 789 break; 790 791 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 792 if (dyn_fin_lifetime >= dyn_keepalive_period) 793 dyn_fin_lifetime = dyn_keepalive_period - 1; 794 q->expire = time_second + dyn_fin_lifetime; 795 break; 796 797 default: 798 #if 0 799 /* 800 * reset or some invalid combination, but can also 801 * occur if we use keep-state the wrong way. 802 */ 803 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 804 kprintf("invalid state: 0x%x\n", q->state); 805 #endif 806 if (dyn_rst_lifetime >= dyn_keepalive_period) 807 dyn_rst_lifetime = dyn_keepalive_period - 1; 808 q->expire = time_second + dyn_rst_lifetime; 809 break; 810 } 811 } else if (pkt->proto == IPPROTO_UDP) { 812 q->expire = time_second + dyn_udp_lifetime; 813 } else { 814 /* other protocols */ 815 q->expire = time_second + dyn_short_lifetime; 816 } 817 done: 818 if (match_direction) 819 *match_direction = dir; 820 return q; 821 } 822 823 static void 824 realloc_dynamic_table(void) 825 { 826 /* 827 * Try reallocation, make sure we have a power of 2 and do 828 * not allow more than 64k entries. In case of overflow, 829 * default to 1024. 830 */ 831 832 if (dyn_buckets > 65536) 833 dyn_buckets = 1024; 834 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 835 dyn_buckets = curr_dyn_buckets; /* reset */ 836 return; 837 } 838 curr_dyn_buckets = dyn_buckets; 839 if (ipfw_dyn_v != NULL) 840 kfree(ipfw_dyn_v, M_IPFW); 841 for (;;) { 842 ipfw_dyn_v = kmalloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 843 M_IPFW, M_WAITOK | M_ZERO); 844 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 845 break; 846 curr_dyn_buckets /= 2; 847 } 848 } 849 850 /** 851 * Install state of type 'type' for a dynamic session. 852 * The hash table contains two type of rules: 853 * - regular rules (O_KEEP_STATE) 854 * - rules for sessions with limited number of sess per user 855 * (O_LIMIT). When they are created, the parent is 856 * increased by 1, and decreased on delete. In this case, 857 * the third parameter is the parent rule and not the chain. 858 * - "parent" rules for the above (O_LIMIT_PARENT). 859 */ 860 static ipfw_dyn_rule * 861 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 862 { 863 ipfw_dyn_rule *r; 864 int i; 865 866 if (ipfw_dyn_v == NULL || 867 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 868 realloc_dynamic_table(); 869 if (ipfw_dyn_v == NULL) 870 return NULL; /* failed ! */ 871 } 872 i = hash_packet(id); 873 874 r = kmalloc(sizeof *r, M_IPFW, M_WAITOK | M_ZERO); 875 if (r == NULL) { 876 kprintf ("sorry cannot allocate state\n"); 877 return NULL; 878 } 879 880 /* increase refcount on parent, and set pointer */ 881 if (dyn_type == O_LIMIT) { 882 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 883 if ( parent->dyn_type != O_LIMIT_PARENT) 884 panic("invalid parent"); 885 parent->count++; 886 r->parent = parent; 887 rule = parent->rule; 888 } 889 890 r->id = *id; 891 r->expire = time_second + dyn_syn_lifetime; 892 r->rule = rule; 893 r->dyn_type = dyn_type; 894 r->pcnt = r->bcnt = 0; 895 r->count = 0; 896 897 r->bucket = i; 898 r->next = ipfw_dyn_v[i]; 899 ipfw_dyn_v[i] = r; 900 dyn_count++; 901 DEB(kprintf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 902 dyn_type, 903 (r->id.src_ip), (r->id.src_port), 904 (r->id.dst_ip), (r->id.dst_port), 905 dyn_count ); ) 906 return r; 907 } 908 909 /** 910 * lookup dynamic parent rule using pkt and rule as search keys. 911 * If the lookup fails, then install one. 912 */ 913 static ipfw_dyn_rule * 914 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 915 { 916 ipfw_dyn_rule *q; 917 int i; 918 919 if (ipfw_dyn_v) { 920 i = hash_packet( pkt ); 921 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 922 if (q->dyn_type == O_LIMIT_PARENT && 923 rule== q->rule && 924 pkt->proto == q->id.proto && 925 pkt->src_ip == q->id.src_ip && 926 pkt->dst_ip == q->id.dst_ip && 927 pkt->src_port == q->id.src_port && 928 pkt->dst_port == q->id.dst_port) { 929 q->expire = time_second + dyn_short_lifetime; 930 DEB(kprintf("lookup_dyn_parent found 0x%p\n",q);) 931 return q; 932 } 933 } 934 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 935 } 936 937 /** 938 * Install dynamic state for rule type cmd->o.opcode 939 * 940 * Returns 1 (failure) if state is not installed because of errors or because 941 * session limitations are enforced. 942 */ 943 static int 944 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 945 struct ip_fw_args *args) 946 { 947 static int last_log; 948 949 ipfw_dyn_rule *q; 950 951 DEB(kprintf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", 952 cmd->o.opcode, 953 (args->f_id.src_ip), (args->f_id.src_port), 954 (args->f_id.dst_ip), (args->f_id.dst_port) );) 955 956 q = lookup_dyn_rule(&args->f_id, NULL, NULL); 957 958 if (q != NULL) { /* should never occur */ 959 if (last_log != time_second) { 960 last_log = time_second; 961 kprintf(" install_state: entry already present, done\n"); 962 } 963 return 0; 964 } 965 966 if (dyn_count >= dyn_max) 967 /* 968 * Run out of slots, try to remove any expired rule. 969 */ 970 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 971 972 if (dyn_count >= dyn_max) { 973 if (last_log != time_second) { 974 last_log = time_second; 975 kprintf("install_state: Too many dynamic rules\n"); 976 } 977 return 1; /* cannot install, notify caller */ 978 } 979 980 switch (cmd->o.opcode) { 981 case O_KEEP_STATE: /* bidir rule */ 982 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 983 break; 984 985 case O_LIMIT: /* limit number of sessions */ 986 { 987 u_int16_t limit_mask = cmd->limit_mask; 988 struct ipfw_flow_id id; 989 ipfw_dyn_rule *parent; 990 991 DEB(kprintf("installing dyn-limit rule %d\n", cmd->conn_limit);) 992 993 id.dst_ip = id.src_ip = 0; 994 id.dst_port = id.src_port = 0; 995 id.proto = args->f_id.proto; 996 997 if (limit_mask & DYN_SRC_ADDR) 998 id.src_ip = args->f_id.src_ip; 999 if (limit_mask & DYN_DST_ADDR) 1000 id.dst_ip = args->f_id.dst_ip; 1001 if (limit_mask & DYN_SRC_PORT) 1002 id.src_port = args->f_id.src_port; 1003 if (limit_mask & DYN_DST_PORT) 1004 id.dst_port = args->f_id.dst_port; 1005 parent = lookup_dyn_parent(&id, rule); 1006 if (parent == NULL) { 1007 kprintf("add parent failed\n"); 1008 return 1; 1009 } 1010 if (parent->count >= cmd->conn_limit) { 1011 /* 1012 * See if we can remove some expired rule. 1013 */ 1014 remove_dyn_rule(rule, parent); 1015 if (parent->count >= cmd->conn_limit) { 1016 if (fw_verbose && last_log != time_second) { 1017 last_log = time_second; 1018 log(LOG_SECURITY | LOG_DEBUG, 1019 "drop session, too many entries\n"); 1020 } 1021 return 1; 1022 } 1023 } 1024 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1025 } 1026 break; 1027 default: 1028 kprintf("unknown dynamic rule type %u\n", cmd->o.opcode); 1029 return 1; 1030 } 1031 lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1032 return 0; 1033 } 1034 1035 /* 1036 * Transmit a TCP packet, containing either a RST or a keepalive. 1037 * When flags & TH_RST, we are sending a RST packet, because of a 1038 * "reset" action matched the packet. 1039 * Otherwise we are sending a keepalive, and flags & TH_ 1040 */ 1041 static void 1042 send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1043 { 1044 struct mbuf *m; 1045 struct ip *ip; 1046 struct tcphdr *tcp; 1047 struct route sro; /* fake route */ 1048 1049 MGETHDR(m, MB_DONTWAIT, MT_HEADER); 1050 if (m == 0) 1051 return; 1052 m->m_pkthdr.rcvif = (struct ifnet *)0; 1053 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1054 m->m_data += max_linkhdr; 1055 1056 ip = mtod(m, struct ip *); 1057 bzero(ip, m->m_len); 1058 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1059 ip->ip_p = IPPROTO_TCP; 1060 tcp->th_off = 5; 1061 /* 1062 * Assume we are sending a RST (or a keepalive in the reverse 1063 * direction), swap src and destination addresses and ports. 1064 */ 1065 ip->ip_src.s_addr = htonl(id->dst_ip); 1066 ip->ip_dst.s_addr = htonl(id->src_ip); 1067 tcp->th_sport = htons(id->dst_port); 1068 tcp->th_dport = htons(id->src_port); 1069 if (flags & TH_RST) { /* we are sending a RST */ 1070 if (flags & TH_ACK) { 1071 tcp->th_seq = htonl(ack); 1072 tcp->th_ack = htonl(0); 1073 tcp->th_flags = TH_RST; 1074 } else { 1075 if (flags & TH_SYN) 1076 seq++; 1077 tcp->th_seq = htonl(0); 1078 tcp->th_ack = htonl(seq); 1079 tcp->th_flags = TH_RST | TH_ACK; 1080 } 1081 } else { 1082 /* 1083 * We are sending a keepalive. flags & TH_SYN determines 1084 * the direction, forward if set, reverse if clear. 1085 * NOTE: seq and ack are always assumed to be correct 1086 * as set by the caller. This may be confusing... 1087 */ 1088 if (flags & TH_SYN) { 1089 /* 1090 * we have to rewrite the correct addresses! 1091 */ 1092 ip->ip_dst.s_addr = htonl(id->dst_ip); 1093 ip->ip_src.s_addr = htonl(id->src_ip); 1094 tcp->th_dport = htons(id->dst_port); 1095 tcp->th_sport = htons(id->src_port); 1096 } 1097 tcp->th_seq = htonl(seq); 1098 tcp->th_ack = htonl(ack); 1099 tcp->th_flags = TH_ACK; 1100 } 1101 /* 1102 * set ip_len to the payload size so we can compute 1103 * the tcp checksum on the pseudoheader 1104 * XXX check this, could save a couple of words ? 1105 */ 1106 ip->ip_len = htons(sizeof(struct tcphdr)); 1107 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1108 /* 1109 * now fill fields left out earlier 1110 */ 1111 ip->ip_ttl = ip_defttl; 1112 ip->ip_len = m->m_pkthdr.len; 1113 bzero (&sro, sizeof (sro)); 1114 ip_rtaddr(ip->ip_dst, &sro); 1115 m->m_pkthdr.fw_flags |= IPFW_MBUF_SKIP_FIREWALL; 1116 ip_output(m, NULL, &sro, 0, NULL, NULL); 1117 if (sro.ro_rt) 1118 RTFREE(sro.ro_rt); 1119 } 1120 1121 /* 1122 * sends a reject message, consuming the mbuf passed as an argument. 1123 */ 1124 static void 1125 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1126 { 1127 1128 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1129 /* We need the IP header in host order for icmp_error(). */ 1130 if (args->eh != NULL) { 1131 struct ip *ip = mtod(args->m, struct ip *); 1132 ip->ip_len = ntohs(ip->ip_len); 1133 ip->ip_off = ntohs(ip->ip_off); 1134 } 1135 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1136 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1137 struct tcphdr *const tcp = 1138 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1139 if ( (tcp->th_flags & TH_RST) == 0) 1140 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1141 ntohl(tcp->th_ack), 1142 tcp->th_flags | TH_RST); 1143 m_freem(args->m); 1144 } else 1145 m_freem(args->m); 1146 args->m = NULL; 1147 } 1148 1149 /** 1150 * 1151 * Given an ip_fw *, lookup_next_rule will return a pointer 1152 * to the next rule, which can be either the jump 1153 * target (for skipto instructions) or the next one in the list (in 1154 * all other cases including a missing jump target). 1155 * The result is also written in the "next_rule" field of the rule. 1156 * Backward jumps are not allowed, so start looking from the next 1157 * rule... 1158 * 1159 * This never returns NULL -- in case we do not have an exact match, 1160 * the next rule is returned. When the ruleset is changed, 1161 * pointers are flushed so we are always correct. 1162 */ 1163 1164 static struct ip_fw * 1165 lookup_next_rule(struct ip_fw *me) 1166 { 1167 struct ip_fw *rule = NULL; 1168 ipfw_insn *cmd; 1169 1170 /* look for action, in case it is a skipto */ 1171 cmd = ACTION_PTR(me); 1172 if (cmd->opcode == O_LOG) 1173 cmd += F_LEN(cmd); 1174 if ( cmd->opcode == O_SKIPTO ) 1175 for (rule = me->next; rule ; rule = rule->next) 1176 if (rule->rulenum >= cmd->arg1) 1177 break; 1178 if (rule == NULL) /* failure or not a skipto */ 1179 rule = me->next; 1180 me->next_rule = rule; 1181 return rule; 1182 } 1183 1184 /* 1185 * The main check routine for the firewall. 1186 * 1187 * All arguments are in args so we can modify them and return them 1188 * back to the caller. 1189 * 1190 * Parameters: 1191 * 1192 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1193 * Starts with the IP header. 1194 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1195 * args->oif Outgoing interface, or NULL if packet is incoming. 1196 * The incoming interface is in the mbuf. (in) 1197 * 1198 * args->rule Pointer to the last matching rule (in/out) 1199 * args->next_hop Socket we are forwarding to (out). 1200 * args->f_id Addresses grabbed from the packet (out) 1201 * 1202 * Return value: 1203 * 1204 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1205 * 0 The packet is to be accepted and routed normally OR 1206 * the packet was denied/rejected and has been dropped; 1207 * in the latter case, *m is equal to NULL upon return. 1208 * port Divert the packet to port, with these caveats: 1209 * 1210 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1211 * of diverting it (ie, 'ipfw tee'). 1212 * 1213 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1214 * 16 bits as a dummynet pipe number instead of diverting 1215 */ 1216 1217 static int 1218 ipfw_chk(struct ip_fw_args *args) 1219 { 1220 /* 1221 * Local variables hold state during the processing of a packet. 1222 * 1223 * IMPORTANT NOTE: to speed up the processing of rules, there 1224 * are some assumption on the values of the variables, which 1225 * are documented here. Should you change them, please check 1226 * the implementation of the various instructions to make sure 1227 * that they still work. 1228 * 1229 * args->eh The MAC header. It is non-null for a layer2 1230 * packet, it is NULL for a layer-3 packet. 1231 * 1232 * m | args->m Pointer to the mbuf, as received from the caller. 1233 * It may change if ipfw_chk() does an m_pullup, or if it 1234 * consumes the packet because it calls send_reject(). 1235 * XXX This has to change, so that ipfw_chk() never modifies 1236 * or consumes the buffer. 1237 * ip is simply an alias of the value of m, and it is kept 1238 * in sync with it (the packet is supposed to start with 1239 * the ip header). 1240 */ 1241 struct mbuf *m = args->m; 1242 struct ip *ip = mtod(m, struct ip *); 1243 1244 /* 1245 * oif | args->oif If NULL, ipfw_chk has been called on the 1246 * inbound path (ether_input, ip_input). 1247 * If non-NULL, ipfw_chk has been called on the outbound path 1248 * (ether_output, ip_output). 1249 */ 1250 struct ifnet *oif = args->oif; 1251 1252 struct ip_fw *f = NULL; /* matching rule */ 1253 int retval = 0; 1254 struct m_tag *mtag; 1255 1256 /* 1257 * hlen The length of the IPv4 header. 1258 * hlen >0 means we have an IPv4 packet. 1259 */ 1260 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1261 1262 /* 1263 * offset The offset of a fragment. offset != 0 means that 1264 * we have a fragment at this offset of an IPv4 packet. 1265 * offset == 0 means that (if this is an IPv4 packet) 1266 * this is the first or only fragment. 1267 */ 1268 u_short offset = 0; 1269 1270 /* 1271 * Local copies of addresses. They are only valid if we have 1272 * an IP packet. 1273 * 1274 * proto The protocol. Set to 0 for non-ip packets, 1275 * or to the protocol read from the packet otherwise. 1276 * proto != 0 means that we have an IPv4 packet. 1277 * 1278 * src_port, dst_port port numbers, in HOST format. Only 1279 * valid for TCP and UDP packets. 1280 * 1281 * src_ip, dst_ip ip addresses, in NETWORK format. 1282 * Only valid for IPv4 packets. 1283 */ 1284 u_int8_t proto; 1285 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1286 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1287 u_int16_t ip_len=0; 1288 int dyn_dir = MATCH_UNKNOWN; 1289 ipfw_dyn_rule *q = NULL; 1290 1291 if (m->m_pkthdr.fw_flags & IPFW_MBUF_SKIP_FIREWALL) 1292 return 0; /* accept */ 1293 /* 1294 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1295 * MATCH_NONE when checked and not matched (q = NULL), 1296 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1297 */ 1298 1299 if (args->eh == NULL || /* layer 3 packet */ 1300 ( m->m_pkthdr.len >= sizeof(struct ip) && 1301 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1302 hlen = ip->ip_hl << 2; 1303 1304 /* 1305 * Collect parameters into local variables for faster matching. 1306 */ 1307 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1308 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1309 goto after_ip_checks; 1310 } 1311 1312 proto = args->f_id.proto = ip->ip_p; 1313 src_ip = ip->ip_src; 1314 dst_ip = ip->ip_dst; 1315 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1316 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1317 ip_len = ntohs(ip->ip_len); 1318 } else { 1319 offset = ip->ip_off & IP_OFFMASK; 1320 ip_len = ip->ip_len; 1321 } 1322 1323 #define PULLUP_TO(len) \ 1324 do { \ 1325 if ((m)->m_len < (len)) { \ 1326 args->m = m = m_pullup(m, (len)); \ 1327 if (m == 0) \ 1328 goto pullup_failed; \ 1329 ip = mtod(m, struct ip *); \ 1330 } \ 1331 } while (0) 1332 1333 if (offset == 0) { 1334 switch (proto) { 1335 case IPPROTO_TCP: 1336 { 1337 struct tcphdr *tcp; 1338 1339 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1340 tcp = L3HDR(struct tcphdr, ip); 1341 dst_port = tcp->th_dport; 1342 src_port = tcp->th_sport; 1343 args->f_id.flags = tcp->th_flags; 1344 } 1345 break; 1346 1347 case IPPROTO_UDP: 1348 { 1349 struct udphdr *udp; 1350 1351 PULLUP_TO(hlen + sizeof(struct udphdr)); 1352 udp = L3HDR(struct udphdr, ip); 1353 dst_port = udp->uh_dport; 1354 src_port = udp->uh_sport; 1355 } 1356 break; 1357 1358 case IPPROTO_ICMP: 1359 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1360 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1361 break; 1362 1363 default: 1364 break; 1365 } 1366 #undef PULLUP_TO 1367 } 1368 1369 args->f_id.src_ip = ntohl(src_ip.s_addr); 1370 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1371 args->f_id.src_port = src_port = ntohs(src_port); 1372 args->f_id.dst_port = dst_port = ntohs(dst_port); 1373 1374 after_ip_checks: 1375 if (args->rule) { 1376 /* 1377 * Packet has already been tagged. Look for the next rule 1378 * to restart processing. 1379 * 1380 * If fw_one_pass != 0 then just accept it. 1381 * XXX should not happen here, but optimized out in 1382 * the caller. 1383 */ 1384 if (fw_one_pass) 1385 return 0; 1386 1387 f = args->rule->next_rule; 1388 if (f == NULL) 1389 f = lookup_next_rule(args->rule); 1390 } else { 1391 /* 1392 * Find the starting rule. It can be either the first 1393 * one, or the one after divert_rule if asked so. 1394 */ 1395 int skipto; 1396 1397 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 1398 if (mtag != NULL) 1399 skipto = *(u_int16_t *)m_tag_data(mtag); 1400 else 1401 skipto = 0; 1402 1403 f = layer3_chain; 1404 if (args->eh == NULL && skipto != 0) { 1405 if (skipto >= IPFW_DEFAULT_RULE) 1406 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1407 while (f && f->rulenum <= skipto) 1408 f = f->next; 1409 if (f == NULL) /* drop packet */ 1410 return(IP_FW_PORT_DENY_FLAG); 1411 } 1412 } 1413 if ((mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL)) != NULL) 1414 m_tag_delete(m, mtag); 1415 1416 /* 1417 * Now scan the rules, and parse microinstructions for each rule. 1418 */ 1419 for (; f; f = f->next) { 1420 int l, cmdlen; 1421 ipfw_insn *cmd; 1422 int skip_or; /* skip rest of OR block */ 1423 1424 again: 1425 if (set_disable & (1 << f->set) ) 1426 continue; 1427 1428 skip_or = 0; 1429 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1430 l -= cmdlen, cmd += cmdlen) { 1431 int match; 1432 1433 /* 1434 * check_body is a jump target used when we find a 1435 * CHECK_STATE, and need to jump to the body of 1436 * the target rule. 1437 */ 1438 1439 check_body: 1440 cmdlen = F_LEN(cmd); 1441 /* 1442 * An OR block (insn_1 || .. || insn_n) has the 1443 * F_OR bit set in all but the last instruction. 1444 * The first match will set "skip_or", and cause 1445 * the following instructions to be skipped until 1446 * past the one with the F_OR bit clear. 1447 */ 1448 if (skip_or) { /* skip this instruction */ 1449 if ((cmd->len & F_OR) == 0) 1450 skip_or = 0; /* next one is good */ 1451 continue; 1452 } 1453 match = 0; /* set to 1 if we succeed */ 1454 1455 switch (cmd->opcode) { 1456 /* 1457 * The first set of opcodes compares the packet's 1458 * fields with some pattern, setting 'match' if a 1459 * match is found. At the end of the loop there is 1460 * logic to deal with F_NOT and F_OR flags associated 1461 * with the opcode. 1462 */ 1463 case O_NOP: 1464 match = 1; 1465 break; 1466 1467 case O_FORWARD_MAC: 1468 kprintf("ipfw: opcode %d unimplemented\n", 1469 cmd->opcode); 1470 break; 1471 1472 case O_GID: 1473 case O_UID: 1474 /* 1475 * We only check offset == 0 && proto != 0, 1476 * as this ensures that we have an IPv4 1477 * packet with the ports info. 1478 */ 1479 if (offset!=0) 1480 break; 1481 { 1482 struct inpcbinfo *pi; 1483 int wildcard; 1484 struct inpcb *pcb; 1485 1486 if (proto == IPPROTO_TCP) { 1487 wildcard = 0; 1488 pi = &tcbinfo[mycpu->gd_cpuid]; 1489 } else if (proto == IPPROTO_UDP) { 1490 wildcard = 1; 1491 pi = &udbinfo; 1492 } else 1493 break; 1494 1495 pcb = (oif) ? 1496 in_pcblookup_hash(pi, 1497 dst_ip, htons(dst_port), 1498 src_ip, htons(src_port), 1499 wildcard, oif) : 1500 in_pcblookup_hash(pi, 1501 src_ip, htons(src_port), 1502 dst_ip, htons(dst_port), 1503 wildcard, NULL); 1504 1505 if (pcb == NULL || pcb->inp_socket == NULL) 1506 break; 1507 #if defined(__DragonFly__) || (defined(__FreeBSD__) && __FreeBSD_version < 500034) 1508 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1509 #endif 1510 if (cmd->opcode == O_UID) { 1511 match = 1512 !socheckuid(pcb->inp_socket, 1513 (uid_t)((ipfw_insn_u32 *)cmd)->d[0]); 1514 } else { 1515 match = groupmember( 1516 (uid_t)((ipfw_insn_u32 *)cmd)->d[0], 1517 pcb->inp_socket->so_cred); 1518 } 1519 } 1520 break; 1521 1522 case O_RECV: 1523 match = iface_match(m->m_pkthdr.rcvif, 1524 (ipfw_insn_if *)cmd); 1525 break; 1526 1527 case O_XMIT: 1528 match = iface_match(oif, (ipfw_insn_if *)cmd); 1529 break; 1530 1531 case O_VIA: 1532 match = iface_match(oif ? oif : 1533 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1534 break; 1535 1536 case O_MACADDR2: 1537 if (args->eh != NULL) { /* have MAC header */ 1538 u_int32_t *want = (u_int32_t *) 1539 ((ipfw_insn_mac *)cmd)->addr; 1540 u_int32_t *mask = (u_int32_t *) 1541 ((ipfw_insn_mac *)cmd)->mask; 1542 u_int32_t *hdr = (u_int32_t *)args->eh; 1543 1544 match = 1545 ( want[0] == (hdr[0] & mask[0]) && 1546 want[1] == (hdr[1] & mask[1]) && 1547 want[2] == (hdr[2] & mask[2]) ); 1548 } 1549 break; 1550 1551 case O_MAC_TYPE: 1552 if (args->eh != NULL) { 1553 u_int16_t t = 1554 ntohs(args->eh->ether_type); 1555 u_int16_t *p = 1556 ((ipfw_insn_u16 *)cmd)->ports; 1557 int i; 1558 1559 for (i = cmdlen - 1; !match && i>0; 1560 i--, p += 2) 1561 match = (t>=p[0] && t<=p[1]); 1562 } 1563 break; 1564 1565 case O_FRAG: 1566 match = (hlen > 0 && offset != 0); 1567 break; 1568 1569 case O_IN: /* "out" is "not in" */ 1570 match = (oif == NULL); 1571 break; 1572 1573 case O_LAYER2: 1574 match = (args->eh != NULL); 1575 break; 1576 1577 case O_PROTO: 1578 /* 1579 * We do not allow an arg of 0 so the 1580 * check of "proto" only suffices. 1581 */ 1582 match = (proto == cmd->arg1); 1583 break; 1584 1585 case O_IP_SRC: 1586 match = (hlen > 0 && 1587 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1588 src_ip.s_addr); 1589 break; 1590 1591 case O_IP_SRC_MASK: 1592 match = (hlen > 0 && 1593 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1594 (src_ip.s_addr & 1595 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1596 break; 1597 1598 case O_IP_SRC_ME: 1599 if (hlen > 0) { 1600 struct ifnet *tif; 1601 1602 INADDR_TO_IFP(src_ip, tif); 1603 match = (tif != NULL); 1604 } 1605 break; 1606 1607 case O_IP_DST_SET: 1608 case O_IP_SRC_SET: 1609 if (hlen > 0) { 1610 u_int32_t *d = (u_int32_t *)(cmd+1); 1611 u_int32_t addr = 1612 cmd->opcode == O_IP_DST_SET ? 1613 args->f_id.dst_ip : 1614 args->f_id.src_ip; 1615 1616 if (addr < d[0]) 1617 break; 1618 addr -= d[0]; /* subtract base */ 1619 match = (addr < cmd->arg1) && 1620 ( d[ 1 + (addr>>5)] & 1621 (1<<(addr & 0x1f)) ); 1622 } 1623 break; 1624 1625 case O_IP_DST: 1626 match = (hlen > 0 && 1627 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1628 dst_ip.s_addr); 1629 break; 1630 1631 case O_IP_DST_MASK: 1632 match = (hlen > 0) && 1633 (((ipfw_insn_ip *)cmd)->addr.s_addr == 1634 (dst_ip.s_addr & 1635 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1636 break; 1637 1638 case O_IP_DST_ME: 1639 if (hlen > 0) { 1640 struct ifnet *tif; 1641 1642 INADDR_TO_IFP(dst_ip, tif); 1643 match = (tif != NULL); 1644 } 1645 break; 1646 1647 case O_IP_SRCPORT: 1648 case O_IP_DSTPORT: 1649 /* 1650 * offset == 0 && proto != 0 is enough 1651 * to guarantee that we have an IPv4 1652 * packet with port info. 1653 */ 1654 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1655 && offset == 0) { 1656 u_int16_t x = 1657 (cmd->opcode == O_IP_SRCPORT) ? 1658 src_port : dst_port ; 1659 u_int16_t *p = 1660 ((ipfw_insn_u16 *)cmd)->ports; 1661 int i; 1662 1663 for (i = cmdlen - 1; !match && i>0; 1664 i--, p += 2) 1665 match = (x>=p[0] && x<=p[1]); 1666 } 1667 break; 1668 1669 case O_ICMPTYPE: 1670 match = (offset == 0 && proto==IPPROTO_ICMP && 1671 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1672 break; 1673 1674 case O_IPOPT: 1675 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1676 break; 1677 1678 case O_IPVER: 1679 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1680 break; 1681 1682 case O_IPTTL: 1683 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl); 1684 break; 1685 1686 case O_IPID: 1687 match = (hlen > 0 && 1688 cmd->arg1 == ntohs(ip->ip_id)); 1689 break; 1690 1691 case O_IPLEN: 1692 match = (hlen > 0 && cmd->arg1 == ip_len); 1693 break; 1694 1695 case O_IPPRECEDENCE: 1696 match = (hlen > 0 && 1697 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1698 break; 1699 1700 case O_IPTOS: 1701 match = (hlen > 0 && 1702 flags_match(cmd, ip->ip_tos)); 1703 break; 1704 1705 case O_TCPFLAGS: 1706 match = (proto == IPPROTO_TCP && offset == 0 && 1707 flags_match(cmd, 1708 L3HDR(struct tcphdr,ip)->th_flags)); 1709 break; 1710 1711 case O_TCPOPTS: 1712 match = (proto == IPPROTO_TCP && offset == 0 && 1713 tcpopts_match(ip, cmd)); 1714 break; 1715 1716 case O_TCPSEQ: 1717 match = (proto == IPPROTO_TCP && offset == 0 && 1718 ((ipfw_insn_u32 *)cmd)->d[0] == 1719 L3HDR(struct tcphdr,ip)->th_seq); 1720 break; 1721 1722 case O_TCPACK: 1723 match = (proto == IPPROTO_TCP && offset == 0 && 1724 ((ipfw_insn_u32 *)cmd)->d[0] == 1725 L3HDR(struct tcphdr,ip)->th_ack); 1726 break; 1727 1728 case O_TCPWIN: 1729 match = (proto == IPPROTO_TCP && offset == 0 && 1730 cmd->arg1 == 1731 L3HDR(struct tcphdr,ip)->th_win); 1732 break; 1733 1734 case O_ESTAB: 1735 /* reject packets which have SYN only */ 1736 /* XXX should i also check for TH_ACK ? */ 1737 match = (proto == IPPROTO_TCP && offset == 0 && 1738 (L3HDR(struct tcphdr,ip)->th_flags & 1739 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1740 break; 1741 1742 case O_LOG: 1743 if (fw_verbose) 1744 ipfw_log(f, hlen, args->eh, m, oif); 1745 match = 1; 1746 break; 1747 1748 case O_PROB: 1749 match = (krandom() < 1750 ((ipfw_insn_u32 *)cmd)->d[0]); 1751 break; 1752 1753 /* 1754 * The second set of opcodes represents 'actions', 1755 * i.e. the terminal part of a rule once the packet 1756 * matches all previous patterns. 1757 * Typically there is only one action for each rule, 1758 * and the opcode is stored at the end of the rule 1759 * (but there are exceptions -- see below). 1760 * 1761 * In general, here we set retval and terminate the 1762 * outer loop (would be a 'break 3' in some language, 1763 * but we need to do a 'goto done'). 1764 * 1765 * Exceptions: 1766 * O_COUNT and O_SKIPTO actions: 1767 * instead of terminating, we jump to the next rule 1768 * ('goto next_rule', equivalent to a 'break 2'), 1769 * or to the SKIPTO target ('goto again' after 1770 * having set f, cmd and l), respectively. 1771 * 1772 * O_LIMIT and O_KEEP_STATE: these opcodes are 1773 * not real 'actions', and are stored right 1774 * before the 'action' part of the rule. 1775 * These opcodes try to install an entry in the 1776 * state tables; if successful, we continue with 1777 * the next opcode (match=1; break;), otherwise 1778 * the packet * must be dropped 1779 * ('goto done' after setting retval); 1780 * 1781 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1782 * cause a lookup of the state table, and a jump 1783 * to the 'action' part of the parent rule 1784 * ('goto check_body') if an entry is found, or 1785 * (CHECK_STATE only) a jump to the next rule if 1786 * the entry is not found ('goto next_rule'). 1787 * The result of the lookup is cached to make 1788 * further instances of these opcodes are 1789 * effectively NOPs. 1790 */ 1791 case O_LIMIT: 1792 case O_KEEP_STATE: 1793 if (install_state(f, 1794 (ipfw_insn_limit *)cmd, args)) { 1795 retval = IP_FW_PORT_DENY_FLAG; 1796 goto done; /* error/limit violation */ 1797 } 1798 match = 1; 1799 break; 1800 1801 case O_PROBE_STATE: 1802 case O_CHECK_STATE: 1803 /* 1804 * dynamic rules are checked at the first 1805 * keep-state or check-state occurrence, 1806 * with the result being stored in dyn_dir. 1807 * The compiler introduces a PROBE_STATE 1808 * instruction for us when we have a 1809 * KEEP_STATE (because PROBE_STATE needs 1810 * to be run first). 1811 */ 1812 if (dyn_dir == MATCH_UNKNOWN && 1813 (q = lookup_dyn_rule(&args->f_id, 1814 &dyn_dir, proto == IPPROTO_TCP ? 1815 L3HDR(struct tcphdr, ip) : NULL)) 1816 != NULL) { 1817 /* 1818 * Found dynamic entry, update stats 1819 * and jump to the 'action' part of 1820 * the parent rule. 1821 */ 1822 q->pcnt++; 1823 q->bcnt += ip_len; 1824 f = q->rule; 1825 cmd = ACTION_PTR(f); 1826 l = f->cmd_len - f->act_ofs; 1827 goto check_body; 1828 } 1829 /* 1830 * Dynamic entry not found. If CHECK_STATE, 1831 * skip to next rule, if PROBE_STATE just 1832 * ignore and continue with next opcode. 1833 */ 1834 if (cmd->opcode == O_CHECK_STATE) 1835 goto next_rule; 1836 match = 1; 1837 break; 1838 1839 case O_ACCEPT: 1840 retval = 0; /* accept */ 1841 goto done; 1842 1843 case O_PIPE: 1844 case O_QUEUE: 1845 args->rule = f; /* report matching rule */ 1846 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 1847 goto done; 1848 1849 case O_DIVERT: 1850 case O_TEE: 1851 if (args->eh) /* not on layer 2 */ 1852 break; 1853 1854 mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, 1855 sizeof(u_int16_t), M_NOWAIT); 1856 if (mtag == NULL) { 1857 retval = IP_FW_PORT_DENY_FLAG; 1858 goto done; 1859 } 1860 *(u_int16_t *)m_tag_data(mtag) = f->rulenum; 1861 m_tag_prepend(m, mtag); 1862 retval = (cmd->opcode == O_DIVERT) ? 1863 cmd->arg1 : 1864 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 1865 goto done; 1866 1867 case O_COUNT: 1868 case O_SKIPTO: 1869 f->pcnt++; /* update stats */ 1870 f->bcnt += ip_len; 1871 f->timestamp = time_second; 1872 if (cmd->opcode == O_COUNT) 1873 goto next_rule; 1874 /* handle skipto */ 1875 if (f->next_rule == NULL) 1876 lookup_next_rule(f); 1877 f = f->next_rule; 1878 goto again; 1879 1880 case O_REJECT: 1881 /* 1882 * Drop the packet and send a reject notice 1883 * if the packet is not ICMP (or is an ICMP 1884 * query), and it is not multicast/broadcast. 1885 */ 1886 if (hlen > 0 && 1887 (proto != IPPROTO_ICMP || 1888 is_icmp_query(ip)) && 1889 !(m->m_flags & (M_BCAST|M_MCAST)) && 1890 !IN_MULTICAST(ntohl(dst_ip.s_addr))) { 1891 send_reject(args, cmd->arg1, 1892 offset,ip_len); 1893 m = args->m; 1894 } 1895 /* FALLTHROUGH */ 1896 case O_DENY: 1897 retval = IP_FW_PORT_DENY_FLAG; 1898 goto done; 1899 1900 case O_FORWARD_IP: 1901 if (args->eh) /* not valid on layer2 pkts */ 1902 break; 1903 if (!q || dyn_dir == MATCH_FORWARD) 1904 args->next_hop = 1905 &((ipfw_insn_sa *)cmd)->sa; 1906 retval = 0; 1907 goto done; 1908 1909 default: 1910 panic("-- unknown opcode %d\n", cmd->opcode); 1911 } /* end of switch() on opcodes */ 1912 1913 if (cmd->len & F_NOT) 1914 match = !match; 1915 1916 if (match) { 1917 if (cmd->len & F_OR) 1918 skip_or = 1; 1919 } else { 1920 if (!(cmd->len & F_OR)) /* not an OR block, */ 1921 break; /* try next rule */ 1922 } 1923 1924 } /* end of inner for, scan opcodes */ 1925 1926 next_rule:; /* try next rule */ 1927 1928 } /* end of outer for, scan rules */ 1929 kprintf("+++ ipfw: ouch!, skip past end of rules, denying packet\n"); 1930 return(IP_FW_PORT_DENY_FLAG); 1931 1932 done: 1933 /* Update statistics */ 1934 f->pcnt++; 1935 f->bcnt += ip_len; 1936 f->timestamp = time_second; 1937 return retval; 1938 1939 pullup_failed: 1940 if (fw_verbose) 1941 kprintf("pullup failed\n"); 1942 return(IP_FW_PORT_DENY_FLAG); 1943 } 1944 1945 /* 1946 * When a rule is added/deleted, clear the next_rule pointers in all rules. 1947 * These will be reconstructed on the fly as packets are matched. 1948 * Must be called at splimp(). 1949 */ 1950 static void 1951 flush_rule_ptrs(void) 1952 { 1953 struct ip_fw *rule; 1954 1955 for (rule = layer3_chain; rule; rule = rule->next) 1956 rule->next_rule = NULL; 1957 } 1958 1959 /* 1960 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 1961 * pipe/queue, or to all of them (match == NULL). 1962 * Must be called at splimp(). 1963 */ 1964 void 1965 flush_pipe_ptrs(struct dn_flow_set *match) 1966 { 1967 struct ip_fw *rule; 1968 1969 for (rule = layer3_chain; rule; rule = rule->next) { 1970 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 1971 1972 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 1973 continue; 1974 if (match == NULL || cmd->pipe_ptr == match) 1975 cmd->pipe_ptr = NULL; 1976 } 1977 } 1978 1979 /* 1980 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 1981 * possibly create a rule number and add the rule to the list. 1982 * Update the rule_number in the input struct so the caller knows it as well. 1983 */ 1984 static int 1985 add_rule(struct ip_fw **head, struct ip_fw *input_rule) 1986 { 1987 struct ip_fw *rule, *f, *prev; 1988 int l = RULESIZE(input_rule); 1989 1990 if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 1991 return (EINVAL); 1992 1993 rule = kmalloc(l, M_IPFW, M_WAITOK | M_ZERO); 1994 if (rule == NULL) 1995 return (ENOSPC); 1996 1997 bcopy(input_rule, rule, l); 1998 1999 rule->next = NULL; 2000 rule->next_rule = NULL; 2001 2002 rule->pcnt = 0; 2003 rule->bcnt = 0; 2004 rule->timestamp = 0; 2005 2006 crit_enter(); 2007 2008 if (*head == NULL) { /* default rule */ 2009 *head = rule; 2010 goto done; 2011 } 2012 2013 /* 2014 * If rulenum is 0, find highest numbered rule before the 2015 * default rule, and add autoinc_step 2016 */ 2017 if (autoinc_step < 1) 2018 autoinc_step = 1; 2019 else if (autoinc_step > 1000) 2020 autoinc_step = 1000; 2021 if (rule->rulenum == 0) { 2022 /* 2023 * locate the highest numbered rule before default 2024 */ 2025 for (f = *head; f; f = f->next) { 2026 if (f->rulenum == IPFW_DEFAULT_RULE) 2027 break; 2028 rule->rulenum = f->rulenum; 2029 } 2030 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2031 rule->rulenum += autoinc_step; 2032 input_rule->rulenum = rule->rulenum; 2033 } 2034 2035 /* 2036 * Now insert the new rule in the right place in the sorted list. 2037 */ 2038 for (prev = NULL, f = *head; f; prev = f, f = f->next) { 2039 if (f->rulenum > rule->rulenum) { /* found the location */ 2040 if (prev) { 2041 rule->next = f; 2042 prev->next = rule; 2043 } else { /* head insert */ 2044 rule->next = *head; 2045 *head = rule; 2046 } 2047 break; 2048 } 2049 } 2050 flush_rule_ptrs(); 2051 done: 2052 static_count++; 2053 static_len += l; 2054 crit_exit(); 2055 DEB(kprintf("++ installed rule %d, static count now %d\n", 2056 rule->rulenum, static_count);) 2057 return (0); 2058 } 2059 2060 /** 2061 * Free storage associated with a static rule (including derived 2062 * dynamic rules). 2063 * The caller is in charge of clearing rule pointers to avoid 2064 * dangling pointers. 2065 * @return a pointer to the next entry. 2066 * Arguments are not checked, so they better be correct. 2067 * Must be called at splimp(). 2068 */ 2069 static struct ip_fw * 2070 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) 2071 { 2072 struct ip_fw *n; 2073 int l = RULESIZE(rule); 2074 2075 n = rule->next; 2076 remove_dyn_rule(rule, NULL /* force removal */); 2077 if (prev == NULL) 2078 *head = n; 2079 else 2080 prev->next = n; 2081 static_count--; 2082 static_len -= l; 2083 2084 if (DUMMYNET_LOADED) 2085 ip_dn_ruledel_ptr(rule); 2086 kfree(rule, M_IPFW); 2087 return n; 2088 } 2089 2090 /* 2091 * Deletes all rules from a chain (including the default rule 2092 * if the second argument is set). 2093 * Must be called at splimp(). 2094 */ 2095 static void 2096 free_chain(struct ip_fw **chain, int kill_default) 2097 { 2098 struct ip_fw *rule; 2099 2100 flush_rule_ptrs(); /* more efficient to do outside the loop */ 2101 2102 while ( (rule = *chain) != NULL && 2103 (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) 2104 delete_rule(chain, NULL, rule); 2105 } 2106 2107 /** 2108 * Remove all rules with given number, and also do set manipulation. 2109 * 2110 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2111 * the next 8 bits are the new set, the top 8 bits are the command: 2112 * 2113 * 0 delete rules with given number 2114 * 1 delete rules with given set number 2115 * 2 move rules with given number to new set 2116 * 3 move rules with given set number to new set 2117 * 4 swap sets with given numbers 2118 */ 2119 static int 2120 del_entry(struct ip_fw **chain, u_int32_t arg) 2121 { 2122 struct ip_fw *prev, *rule; 2123 u_int16_t rulenum; 2124 u_int8_t cmd, new_set; 2125 2126 rulenum = arg & 0xffff; 2127 cmd = (arg >> 24) & 0xff; 2128 new_set = (arg >> 16) & 0xff; 2129 2130 if (cmd > 4) 2131 return EINVAL; 2132 if (new_set > 30) 2133 return EINVAL; 2134 if (cmd == 0 || cmd == 2) { 2135 if (rulenum == IPFW_DEFAULT_RULE) 2136 return EINVAL; 2137 } else { 2138 if (rulenum > 30) 2139 return EINVAL; 2140 } 2141 2142 switch (cmd) { 2143 case 0: /* delete rules with given number */ 2144 /* 2145 * locate first rule to delete 2146 */ 2147 for (prev = NULL, rule = *chain; 2148 rule && rule->rulenum < rulenum; 2149 prev = rule, rule = rule->next) 2150 ; 2151 if (rule->rulenum != rulenum) 2152 return EINVAL; 2153 2154 crit_enter(); /* no access to rules while removing */ 2155 /* 2156 * flush pointers outside the loop, then delete all matching 2157 * rules. prev remains the same throughout the cycle. 2158 */ 2159 flush_rule_ptrs(); 2160 while (rule && rule->rulenum == rulenum) 2161 rule = delete_rule(chain, prev, rule); 2162 crit_exit(); 2163 break; 2164 2165 case 1: /* delete all rules with given set number */ 2166 crit_enter(); 2167 flush_rule_ptrs(); 2168 for (prev = NULL, rule = *chain; rule ; ) 2169 if (rule->set == rulenum) 2170 rule = delete_rule(chain, prev, rule); 2171 else { 2172 prev = rule; 2173 rule = rule->next; 2174 } 2175 crit_exit(); 2176 break; 2177 2178 case 2: /* move rules with given number to new set */ 2179 crit_enter(); 2180 for (rule = *chain; rule ; rule = rule->next) 2181 if (rule->rulenum == rulenum) 2182 rule->set = new_set; 2183 crit_exit(); 2184 break; 2185 2186 case 3: /* move rules with given set number to new set */ 2187 crit_enter(); 2188 for (rule = *chain; rule ; rule = rule->next) 2189 if (rule->set == rulenum) 2190 rule->set = new_set; 2191 crit_exit(); 2192 break; 2193 2194 case 4: /* swap two sets */ 2195 crit_enter(); 2196 for (rule = *chain; rule ; rule = rule->next) 2197 if (rule->set == rulenum) 2198 rule->set = new_set; 2199 else if (rule->set == new_set) 2200 rule->set = rulenum; 2201 crit_exit(); 2202 break; 2203 } 2204 return 0; 2205 } 2206 2207 /* 2208 * Clear counters for a specific rule. 2209 */ 2210 static void 2211 clear_counters(struct ip_fw *rule, int log_only) 2212 { 2213 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2214 2215 if (log_only == 0) { 2216 rule->bcnt = rule->pcnt = 0; 2217 rule->timestamp = 0; 2218 } 2219 if (l->o.opcode == O_LOG) 2220 l->log_left = l->max_log; 2221 } 2222 2223 /** 2224 * Reset some or all counters on firewall rules. 2225 * @arg frwl is null to clear all entries, or contains a specific 2226 * rule number. 2227 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2228 */ 2229 static int 2230 zero_entry(int rulenum, int log_only) 2231 { 2232 struct ip_fw *rule; 2233 char *msg; 2234 2235 if (rulenum == 0) { 2236 crit_enter(); 2237 norule_counter = 0; 2238 for (rule = layer3_chain; rule; rule = rule->next) 2239 clear_counters(rule, log_only); 2240 crit_exit(); 2241 msg = log_only ? "ipfw: All logging counts reset.\n" : 2242 "ipfw: Accounting cleared.\n"; 2243 } else { 2244 int cleared = 0; 2245 /* 2246 * We can have multiple rules with the same number, so we 2247 * need to clear them all. 2248 */ 2249 for (rule = layer3_chain; rule; rule = rule->next) 2250 if (rule->rulenum == rulenum) { 2251 crit_enter(); 2252 while (rule && rule->rulenum == rulenum) { 2253 clear_counters(rule, log_only); 2254 rule = rule->next; 2255 } 2256 crit_exit(); 2257 cleared = 1; 2258 break; 2259 } 2260 if (!cleared) /* we did not find any matching rules */ 2261 return (EINVAL); 2262 msg = log_only ? "ipfw: Entry %d logging count reset.\n" : 2263 "ipfw: Entry %d cleared.\n"; 2264 } 2265 if (fw_verbose) 2266 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); 2267 return (0); 2268 } 2269 2270 /* 2271 * Check validity of the structure before insert. 2272 * Fortunately rules are simple, so this mostly need to check rule sizes. 2273 */ 2274 static int 2275 check_ipfw_struct(struct ip_fw *rule, int size) 2276 { 2277 int l, cmdlen = 0; 2278 int have_action=0; 2279 ipfw_insn *cmd; 2280 2281 if (size < sizeof(*rule)) { 2282 kprintf("ipfw: rule too short\n"); 2283 return (EINVAL); 2284 } 2285 /* first, check for valid size */ 2286 l = RULESIZE(rule); 2287 if (l != size) { 2288 kprintf("ipfw: size mismatch (have %d want %d)\n", size, l); 2289 return (EINVAL); 2290 } 2291 /* 2292 * Now go for the individual checks. Very simple ones, basically only 2293 * instruction sizes. 2294 */ 2295 for (l = rule->cmd_len, cmd = rule->cmd ; 2296 l > 0 ; l -= cmdlen, cmd += cmdlen) { 2297 cmdlen = F_LEN(cmd); 2298 if (cmdlen > l) { 2299 kprintf("ipfw: opcode %d size truncated\n", 2300 cmd->opcode); 2301 return EINVAL; 2302 } 2303 DEB(kprintf("ipfw: opcode %d\n", cmd->opcode);) 2304 switch (cmd->opcode) { 2305 case O_NOP: 2306 case O_PROBE_STATE: 2307 case O_KEEP_STATE: 2308 case O_PROTO: 2309 case O_IP_SRC_ME: 2310 case O_IP_DST_ME: 2311 case O_LAYER2: 2312 case O_IN: 2313 case O_FRAG: 2314 case O_IPOPT: 2315 case O_IPLEN: 2316 case O_IPID: 2317 case O_IPTOS: 2318 case O_IPPRECEDENCE: 2319 case O_IPTTL: 2320 case O_IPVER: 2321 case O_TCPWIN: 2322 case O_TCPFLAGS: 2323 case O_TCPOPTS: 2324 case O_ESTAB: 2325 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2326 goto bad_size; 2327 break; 2328 2329 case O_UID: 2330 case O_GID: 2331 case O_IP_SRC: 2332 case O_IP_DST: 2333 case O_TCPSEQ: 2334 case O_TCPACK: 2335 case O_PROB: 2336 case O_ICMPTYPE: 2337 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) 2338 goto bad_size; 2339 break; 2340 2341 case O_LIMIT: 2342 if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) 2343 goto bad_size; 2344 break; 2345 2346 case O_LOG: 2347 if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) 2348 goto bad_size; 2349 2350 ((ipfw_insn_log *)cmd)->log_left = 2351 ((ipfw_insn_log *)cmd)->max_log; 2352 2353 break; 2354 2355 case O_IP_SRC_MASK: 2356 case O_IP_DST_MASK: 2357 if (cmdlen != F_INSN_SIZE(ipfw_insn_ip)) 2358 goto bad_size; 2359 if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) { 2360 kprintf("ipfw: opcode %d, useless rule\n", 2361 cmd->opcode); 2362 return EINVAL; 2363 } 2364 break; 2365 2366 case O_IP_SRC_SET: 2367 case O_IP_DST_SET: 2368 if (cmd->arg1 == 0 || cmd->arg1 > 256) { 2369 kprintf("ipfw: invalid set size %d\n", 2370 cmd->arg1); 2371 return EINVAL; 2372 } 2373 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + 2374 (cmd->arg1+31)/32 ) 2375 goto bad_size; 2376 break; 2377 2378 case O_MACADDR2: 2379 if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) 2380 goto bad_size; 2381 break; 2382 2383 case O_MAC_TYPE: 2384 case O_IP_SRCPORT: 2385 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ 2386 if (cmdlen < 2 || cmdlen > 31) 2387 goto bad_size; 2388 break; 2389 2390 case O_RECV: 2391 case O_XMIT: 2392 case O_VIA: 2393 if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) 2394 goto bad_size; 2395 break; 2396 2397 case O_PIPE: 2398 case O_QUEUE: 2399 if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) 2400 goto bad_size; 2401 goto check_action; 2402 2403 case O_FORWARD_IP: 2404 if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) 2405 goto bad_size; 2406 goto check_action; 2407 2408 case O_FORWARD_MAC: /* XXX not implemented yet */ 2409 case O_CHECK_STATE: 2410 case O_COUNT: 2411 case O_ACCEPT: 2412 case O_DENY: 2413 case O_REJECT: 2414 case O_SKIPTO: 2415 case O_DIVERT: 2416 case O_TEE: 2417 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2418 goto bad_size; 2419 check_action: 2420 if (have_action) { 2421 kprintf("ipfw: opcode %d, multiple actions" 2422 " not allowed\n", 2423 cmd->opcode); 2424 return EINVAL; 2425 } 2426 have_action = 1; 2427 if (l != cmdlen) { 2428 kprintf("ipfw: opcode %d, action must be" 2429 " last opcode\n", 2430 cmd->opcode); 2431 return EINVAL; 2432 } 2433 break; 2434 default: 2435 kprintf("ipfw: opcode %d, unknown opcode\n", 2436 cmd->opcode); 2437 return EINVAL; 2438 } 2439 } 2440 if (have_action == 0) { 2441 kprintf("ipfw: missing action\n"); 2442 return EINVAL; 2443 } 2444 return 0; 2445 2446 bad_size: 2447 kprintf("ipfw: opcode %d size %d wrong\n", 2448 cmd->opcode, cmdlen); 2449 return EINVAL; 2450 } 2451 2452 2453 /** 2454 * {set|get}sockopt parser. 2455 */ 2456 static int 2457 ipfw_ctl(struct sockopt *sopt) 2458 { 2459 int error, rulenum; 2460 size_t size; 2461 struct ip_fw *bp , *buf, *rule; 2462 2463 static u_int32_t rule_buf[255]; /* we copy the data here */ 2464 2465 /* 2466 * Disallow modifications in really-really secure mode, but still allow 2467 * the logging counters to be reset. 2468 */ 2469 if (sopt->sopt_name == IP_FW_ADD || 2470 (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { 2471 #if defined(__FreeBSD__) && __FreeBSD_version >= 500034 2472 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); 2473 if (error) 2474 return (error); 2475 #else /* FreeBSD 4.x */ 2476 if (securelevel >= 3) 2477 return (EPERM); 2478 #endif 2479 } 2480 2481 error = 0; 2482 2483 switch (sopt->sopt_name) { 2484 case IP_FW_GET: 2485 /* 2486 * pass up a copy of the current rules. Static rules 2487 * come first (the last of which has number IPFW_DEFAULT_RULE), 2488 * followed by a possibly empty list of dynamic rule. 2489 * The last dynamic rule has NULL in the "next" field. 2490 */ 2491 crit_enter(); 2492 size = static_len; /* size of static rules */ 2493 if (ipfw_dyn_v) /* add size of dyn.rules */ 2494 size += (dyn_count * sizeof(ipfw_dyn_rule)); 2495 2496 /* 2497 * XXX todo: if the user passes a short length just to know 2498 * how much room is needed, do not bother filling up the 2499 * buffer, just jump to the sooptcopyout. 2500 */ 2501 buf = kmalloc(size, M_TEMP, M_WAITOK); 2502 2503 bp = buf; 2504 for (rule = layer3_chain; rule ; rule = rule->next) { 2505 int i = RULESIZE(rule); 2506 bcopy(rule, bp, i); 2507 /* 2508 * abuse 'next_rule' to store the set_disable word 2509 */ 2510 bcopy(&set_disable, &(((struct ip_fw *)bp)->next_rule), 2511 sizeof(set_disable)); 2512 bp = (struct ip_fw *)((char *)bp + i); 2513 } 2514 if (ipfw_dyn_v) { 2515 int i; 2516 ipfw_dyn_rule *p, *dst, *last = NULL; 2517 2518 dst = (ipfw_dyn_rule *)bp; 2519 for (i = 0 ; i < curr_dyn_buckets ; i++ ) 2520 for ( p = ipfw_dyn_v[i] ; p != NULL ; 2521 p = p->next, dst++ ) { 2522 bcopy(p, dst, sizeof *p); 2523 bcopy(&(p->rule->rulenum), &(dst->rule), 2524 sizeof(p->rule->rulenum)); 2525 /* 2526 * store a non-null value in "next". 2527 * The userland code will interpret a 2528 * NULL here as a marker 2529 * for the last dynamic rule. 2530 */ 2531 dst->next = dst ; 2532 last = dst ; 2533 dst->expire = 2534 TIME_LEQ(dst->expire, time_second) ? 2535 0 : dst->expire - time_second ; 2536 } 2537 if (last != NULL) /* mark last dynamic rule */ 2538 last->next = NULL; 2539 } 2540 crit_exit(); 2541 2542 error = sooptcopyout(sopt, buf, size); 2543 kfree(buf, M_TEMP); 2544 break; 2545 2546 case IP_FW_FLUSH: 2547 /* 2548 * Normally we cannot release the lock on each iteration. 2549 * We could do it here only because we start from the head all 2550 * the times so there is no risk of missing some entries. 2551 * On the other hand, the risk is that we end up with 2552 * a very inconsistent ruleset, so better keep the lock 2553 * around the whole cycle. 2554 * 2555 * XXX this code can be improved by resetting the head of 2556 * the list to point to the default rule, and then freeing 2557 * the old list without the need for a lock. 2558 */ 2559 2560 crit_enter(); 2561 free_chain(&layer3_chain, 0 /* keep default rule */); 2562 crit_exit(); 2563 break; 2564 2565 case IP_FW_ADD: 2566 rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ 2567 error = sooptcopyin(sopt, rule, sizeof(rule_buf), 2568 sizeof(struct ip_fw) ); 2569 size = sopt->sopt_valsize; 2570 if (error || (error = check_ipfw_struct(rule, size))) 2571 break; 2572 2573 error = add_rule(&layer3_chain, rule); 2574 size = RULESIZE(rule); 2575 if (!error && sopt->sopt_dir == SOPT_GET) 2576 error = sooptcopyout(sopt, rule, size); 2577 break; 2578 2579 case IP_FW_DEL: 2580 /* 2581 * IP_FW_DEL is used for deleting single rules or sets, 2582 * and (ab)used to atomically manipulate sets. Argument size 2583 * is used to distinguish between the two: 2584 * sizeof(u_int32_t) 2585 * delete single rule or set of rules, 2586 * or reassign rules (or sets) to a different set. 2587 * 2*sizeof(u_int32_t) 2588 * atomic disable/enable sets. 2589 * first u_int32_t contains sets to be disabled, 2590 * second u_int32_t contains sets to be enabled. 2591 */ 2592 error = sooptcopyin(sopt, rule_buf, 2593 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2594 if (error) 2595 break; 2596 size = sopt->sopt_valsize; 2597 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2598 error = del_entry(&layer3_chain, rule_buf[0]); 2599 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2600 set_disable = 2601 (set_disable | rule_buf[0]) & ~rule_buf[1] & 2602 ~(1<<31); /* set 31 always enabled */ 2603 else 2604 error = EINVAL; 2605 break; 2606 2607 case IP_FW_ZERO: 2608 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2609 rulenum=0; 2610 2611 if (sopt->sopt_val != 0) { 2612 error = sooptcopyin(sopt, &rulenum, 2613 sizeof(int), sizeof(int)); 2614 if (error) 2615 break; 2616 } 2617 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); 2618 break; 2619 2620 default: 2621 kprintf("ipfw_ctl invalid option %d\n", sopt->sopt_name); 2622 error = EINVAL; 2623 } 2624 2625 return (error); 2626 } 2627 2628 /** 2629 * dummynet needs a reference to the default rule, because rules can be 2630 * deleted while packets hold a reference to them. When this happens, 2631 * dummynet changes the reference to the default rule (it could well be a 2632 * NULL pointer, but this way we do not need to check for the special 2633 * case, plus here he have info on the default behaviour). 2634 */ 2635 struct ip_fw *ip_fw_default_rule; 2636 2637 /* 2638 * This procedure is only used to handle keepalives. It is invoked 2639 * every dyn_keepalive_period 2640 */ 2641 static void 2642 ipfw_tick(void * __unused unused) 2643 { 2644 int i; 2645 ipfw_dyn_rule *q; 2646 2647 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2648 goto done; 2649 2650 crit_enter(); 2651 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2652 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2653 if (q->dyn_type == O_LIMIT_PARENT) 2654 continue; 2655 if (q->id.proto != IPPROTO_TCP) 2656 continue; 2657 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2658 continue; 2659 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2660 q->expire)) 2661 continue; /* too early */ 2662 if (TIME_LEQ(q->expire, time_second)) 2663 continue; /* too late, rule expired */ 2664 2665 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2666 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2667 } 2668 } 2669 crit_exit(); 2670 done: 2671 callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz, 2672 ipfw_tick, NULL); 2673 } 2674 2675 static void 2676 ipfw_init(void) 2677 { 2678 struct ip_fw default_rule; 2679 2680 ip_fw_chk_ptr = ipfw_chk; 2681 ip_fw_ctl_ptr = ipfw_ctl; 2682 layer3_chain = NULL; 2683 2684 bzero(&default_rule, sizeof default_rule); 2685 2686 default_rule.act_ofs = 0; 2687 default_rule.rulenum = IPFW_DEFAULT_RULE; 2688 default_rule.cmd_len = 1; 2689 default_rule.set = 31; 2690 2691 default_rule.cmd[0].len = 1; 2692 default_rule.cmd[0].opcode = 2693 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2694 1 ? O_ACCEPT : 2695 #endif 2696 O_DENY; 2697 2698 add_rule(&layer3_chain, &default_rule); 2699 2700 ip_fw_default_rule = layer3_chain; 2701 kprintf("ipfw2 initialized, divert %s, " 2702 "rule-based forwarding enabled, default to %s, logging ", 2703 #ifdef IPDIVERT 2704 "enabled", 2705 #else 2706 "disabled", 2707 #endif 2708 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2709 2710 #ifdef IPFIREWALL_VERBOSE 2711 fw_verbose = 1; 2712 #endif 2713 #ifdef IPFIREWALL_VERBOSE_LIMIT 2714 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2715 #endif 2716 if (fw_verbose == 0) 2717 kprintf("disabled\n"); 2718 else if (verbose_limit == 0) 2719 kprintf("unlimited\n"); 2720 else 2721 kprintf("limited to %d packets/entry by default\n", 2722 verbose_limit); 2723 callout_init(&ipfw_timeout_h); 2724 callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL); 2725 } 2726 2727 static int 2728 ipfw_modevent(module_t mod, int type, void *unused) 2729 { 2730 int err = 0; 2731 2732 switch (type) { 2733 case MOD_LOAD: 2734 crit_enter(); 2735 if (IPFW_LOADED) { 2736 crit_exit(); 2737 kprintf("IP firewall already loaded\n"); 2738 err = EEXIST; 2739 } else { 2740 ipfw_init(); 2741 crit_exit(); 2742 } 2743 break; 2744 2745 case MOD_UNLOAD: 2746 #if !defined(KLD_MODULE) 2747 kprintf("ipfw statically compiled, cannot unload\n"); 2748 err = EBUSY; 2749 #else 2750 crit_enter(); 2751 callout_stop(&ipfw_timeout_h); 2752 ip_fw_chk_ptr = NULL; 2753 ip_fw_ctl_ptr = NULL; 2754 free_chain(&layer3_chain, 1 /* kill default rule */); 2755 crit_exit(); 2756 kprintf("IP firewall unloaded\n"); 2757 #endif 2758 break; 2759 default: 2760 break; 2761 } 2762 return err; 2763 } 2764 2765 static moduledata_t ipfwmod = { 2766 "ipfw", 2767 ipfw_modevent, 2768 0 2769 }; 2770 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); 2771 MODULE_VERSION(ipfw, 1); 2772 #endif /* IPFW2 */ 2773