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 1.31 2007/10/29 12:23:57 sephe Exp $ 27 */ 28 29 #define DEB(x) 30 #define DDB(x) x 31 32 /* 33 * Implement IP packet firewall (new version) 34 */ 35 36 #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 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/malloc.h> 49 #include <sys/mbuf.h> 50 #include <sys/kernel.h> 51 #include <sys/proc.h> 52 #include <sys/socket.h> 53 #include <sys/socketvar.h> 54 #include <sys/sysctl.h> 55 #include <sys/syslog.h> 56 #include <sys/thread2.h> 57 #include <sys/ucred.h> 58 #include <sys/in_cksum.h> 59 #include <net/if.h> 60 #include <net/route.h> 61 #include <netinet/in.h> 62 #include <netinet/in_systm.h> 63 #include <netinet/in_var.h> 64 #include <netinet/in_pcb.h> 65 #include <netinet/ip.h> 66 #include <netinet/ip_var.h> 67 #include <netinet/ip_icmp.h> 68 #include "ip_fw.h" 69 #include <net/dummynet/ip_dummynet.h> 70 #include <netinet/tcp.h> 71 #include <netinet/tcp_timer.h> 72 #include <netinet/tcp_var.h> 73 #include <netinet/tcpip.h> 74 #include <netinet/udp.h> 75 #include <netinet/udp_var.h> 76 77 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */ 78 79 /* 80 * set_disable contains one bit per set value (0..31). 81 * If the bit is set, all rules with the corresponding set 82 * are disabled. Set 31 is reserved for the default rule 83 * and CANNOT be disabled. 84 */ 85 static u_int32_t set_disable; 86 87 static int fw_verbose; 88 static int verbose_limit; 89 90 static struct callout ipfw_timeout_h; 91 #define IPFW_DEFAULT_RULE 65535 92 93 /* 94 * list of rules for layer 3 95 */ 96 static struct ip_fw *layer3_chain; 97 98 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 99 100 static int fw_debug = 1; 101 static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 102 103 #ifdef SYSCTL_NODE 104 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 105 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, 106 &fw_enable, 0, "Enable ipfw"); 107 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 108 &autoinc_step, 0, "Rule number autincrement step"); 109 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, 110 &fw_one_pass, 0, 111 "Only do a single pass through ipfw when using dummynet(4)"); 112 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 113 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 114 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, 115 &fw_verbose, 0, "Log matches to ipfw rules"); 116 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 117 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 118 119 /* 120 * Description of dynamic rules. 121 * 122 * Dynamic rules are stored in lists accessed through a hash table 123 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 124 * be modified through the sysctl variable dyn_buckets which is 125 * updated when the table becomes empty. 126 * 127 * XXX currently there is only one list, ipfw_dyn. 128 * 129 * When a packet is received, its address fields are first masked 130 * with the mask defined for the rule, then hashed, then matched 131 * against the entries in the corresponding list. 132 * Dynamic rules can be used for different purposes: 133 * + stateful rules; 134 * + enforcing limits on the number of sessions; 135 * + in-kernel NAT (not implemented yet) 136 * 137 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 138 * measured in seconds and depending on the flags. 139 * 140 * The total number of dynamic rules is stored in dyn_count. 141 * The max number of dynamic rules is dyn_max. When we reach 142 * the maximum number of rules we do not create anymore. This is 143 * done to avoid consuming too much memory, but also too much 144 * time when searching on each packet (ideally, we should try instead 145 * to put a limit on the length of the list on each bucket...). 146 * 147 * Each dynamic rule holds a pointer to the parent ipfw rule so 148 * we know what action to perform. Dynamic rules are removed when 149 * the parent rule is deleted. XXX we should make them survive. 150 * 151 * There are some limitations with dynamic rules -- we do not 152 * obey the 'randomized match', and we do not do multiple 153 * passes through the firewall. XXX check the latter!!! 154 */ 155 static ipfw_dyn_rule **ipfw_dyn_v = NULL; 156 static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 157 static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 158 159 /* 160 * Timeouts for various events in handing dynamic rules. 161 */ 162 static u_int32_t dyn_ack_lifetime = 300; 163 static u_int32_t dyn_syn_lifetime = 20; 164 static u_int32_t dyn_fin_lifetime = 1; 165 static u_int32_t dyn_rst_lifetime = 1; 166 static u_int32_t dyn_udp_lifetime = 10; 167 static u_int32_t dyn_short_lifetime = 5; 168 169 /* 170 * Keepalives are sent if dyn_keepalive is set. They are sent every 171 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 172 * seconds of lifetime of a rule. 173 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 174 * than dyn_keepalive_period. 175 */ 176 177 static u_int32_t dyn_keepalive_interval = 20; 178 static u_int32_t dyn_keepalive_period = 5; 179 static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 180 181 static u_int32_t static_count; /* # of static rules */ 182 static u_int32_t static_len; /* size in bytes of static rules */ 183 static u_int32_t dyn_count; /* # of dynamic rules */ 184 static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 185 186 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 187 &dyn_buckets, 0, "Number of dyn. buckets"); 188 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 189 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 190 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 191 &dyn_count, 0, "Number of dyn. rules"); 192 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 193 &dyn_max, 0, "Max number of dyn. rules"); 194 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 195 &static_count, 0, "Number of static rules"); 196 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 197 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 198 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 199 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 200 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 201 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 202 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 203 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 204 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 205 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 206 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 207 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 208 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 209 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 210 211 #endif /* SYSCTL_NODE */ 212 213 214 static ip_fw_chk_t ipfw_chk; 215 216 ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 217 218 /* 219 * This macro maps an ip pointer into a layer3 header pointer of type T 220 */ 221 #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 222 223 static __inline int 224 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 225 { 226 int type = L3HDR(struct icmp,ip)->icmp_type; 227 228 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 229 } 230 231 #define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 232 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 233 234 static int 235 is_icmp_query(struct ip *ip) 236 { 237 int type = L3HDR(struct icmp, ip)->icmp_type; 238 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 239 } 240 #undef TT 241 242 /* 243 * The following checks use two arrays of 8 or 16 bits to store the 244 * bits that we want set or clear, respectively. They are in the 245 * low and high half of cmd->arg1 or cmd->d[0]. 246 * 247 * We scan options and store the bits we find set. We succeed if 248 * 249 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 250 * 251 * The code is sometimes optimized not to store additional variables. 252 */ 253 254 static int 255 flags_match(ipfw_insn *cmd, u_int8_t bits) 256 { 257 u_char want_clear; 258 bits = ~bits; 259 260 if ( ((cmd->arg1 & 0xff) & bits) != 0) 261 return 0; /* some bits we want set were clear */ 262 want_clear = (cmd->arg1 >> 8) & 0xff; 263 if ( (want_clear & bits) != want_clear) 264 return 0; /* some bits we want clear were set */ 265 return 1; 266 } 267 268 static int 269 ipopts_match(struct ip *ip, ipfw_insn *cmd) 270 { 271 int optlen, bits = 0; 272 u_char *cp = (u_char *)(ip + 1); 273 int x = (ip->ip_hl << 2) - sizeof (struct ip); 274 275 for (; x > 0; x -= optlen, cp += optlen) { 276 int opt = cp[IPOPT_OPTVAL]; 277 278 if (opt == IPOPT_EOL) 279 break; 280 if (opt == IPOPT_NOP) 281 optlen = 1; 282 else { 283 optlen = cp[IPOPT_OLEN]; 284 if (optlen <= 0 || optlen > x) 285 return 0; /* invalid or truncated */ 286 } 287 switch (opt) { 288 289 default: 290 break; 291 292 case IPOPT_LSRR: 293 bits |= IP_FW_IPOPT_LSRR; 294 break; 295 296 case IPOPT_SSRR: 297 bits |= IP_FW_IPOPT_SSRR; 298 break; 299 300 case IPOPT_RR: 301 bits |= IP_FW_IPOPT_RR; 302 break; 303 304 case IPOPT_TS: 305 bits |= IP_FW_IPOPT_TS; 306 break; 307 } 308 } 309 return (flags_match(cmd, bits)); 310 } 311 312 static int 313 tcpopts_match(struct ip *ip, ipfw_insn *cmd) 314 { 315 int optlen, bits = 0; 316 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 317 u_char *cp = (u_char *)(tcp + 1); 318 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 319 320 for (; x > 0; x -= optlen, cp += optlen) { 321 int opt = cp[0]; 322 if (opt == TCPOPT_EOL) 323 break; 324 if (opt == TCPOPT_NOP) 325 optlen = 1; 326 else { 327 optlen = cp[1]; 328 if (optlen <= 0) 329 break; 330 } 331 332 switch (opt) { 333 334 default: 335 break; 336 337 case TCPOPT_MAXSEG: 338 bits |= IP_FW_TCPOPT_MSS; 339 break; 340 341 case TCPOPT_WINDOW: 342 bits |= IP_FW_TCPOPT_WINDOW; 343 break; 344 345 case TCPOPT_SACK_PERMITTED: 346 case TCPOPT_SACK: 347 bits |= IP_FW_TCPOPT_SACK; 348 break; 349 350 case TCPOPT_TIMESTAMP: 351 bits |= IP_FW_TCPOPT_TS; 352 break; 353 354 case TCPOPT_CC: 355 case TCPOPT_CCNEW: 356 case TCPOPT_CCECHO: 357 bits |= IP_FW_TCPOPT_CC; 358 break; 359 } 360 } 361 return (flags_match(cmd, bits)); 362 } 363 364 static int 365 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 366 { 367 if (ifp == NULL) /* no iface with this packet, match fails */ 368 return 0; 369 /* Check by name or by IP address */ 370 if (cmd->name[0] != '\0') { /* match by name */ 371 /* Check name */ 372 if (cmd->p.glob) { 373 if (kfnmatch(cmd->name, ifp->if_xname, 0) == 0) 374 return(1); 375 } else { 376 if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) 377 return(1); 378 } 379 } else { 380 struct ifaddr *ia; 381 382 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 383 if (ia->ifa_addr == NULL) 384 continue; 385 if (ia->ifa_addr->sa_family != AF_INET) 386 continue; 387 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 388 (ia->ifa_addr))->sin_addr.s_addr) 389 return(1); /* match */ 390 } 391 } 392 return(0); /* no match, fail ... */ 393 } 394 395 static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 396 397 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 398 #define SNP(buf) buf, sizeof(buf) 399 400 /* 401 * We enter here when we have a rule with O_LOG. 402 * XXX this function alone takes about 2Kbytes of code! 403 */ 404 static void 405 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 406 struct mbuf *m, struct ifnet *oif) 407 { 408 char *action; 409 int limit_reached = 0; 410 char action2[40], proto[48], fragment[28]; 411 412 fragment[0] = '\0'; 413 proto[0] = '\0'; 414 415 if (f == NULL) { /* bogus pkt */ 416 if (verbose_limit != 0 && norule_counter >= verbose_limit) 417 return; 418 norule_counter++; 419 if (norule_counter == verbose_limit) 420 limit_reached = verbose_limit; 421 action = "Refuse"; 422 } else { /* O_LOG is the first action, find the real one */ 423 ipfw_insn *cmd = ACTION_PTR(f); 424 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 425 426 if (l->max_log != 0 && l->log_left == 0) 427 return; 428 l->log_left--; 429 if (l->log_left == 0) 430 limit_reached = l->max_log; 431 cmd += F_LEN(cmd); /* point to first action */ 432 if (cmd->opcode == O_PROB) 433 cmd += F_LEN(cmd); 434 435 action = action2; 436 switch (cmd->opcode) { 437 case O_DENY: 438 action = "Deny"; 439 break; 440 441 case O_REJECT: 442 if (cmd->arg1==ICMP_REJECT_RST) 443 action = "Reset"; 444 else if (cmd->arg1==ICMP_UNREACH_HOST) 445 action = "Reject"; 446 else 447 ksnprintf(SNPARGS(action2, 0), "Unreach %d", 448 cmd->arg1); 449 break; 450 451 case O_ACCEPT: 452 action = "Accept"; 453 break; 454 case O_COUNT: 455 action = "Count"; 456 break; 457 case O_DIVERT: 458 ksnprintf(SNPARGS(action2, 0), "Divert %d", 459 cmd->arg1); 460 break; 461 case O_TEE: 462 ksnprintf(SNPARGS(action2, 0), "Tee %d", 463 cmd->arg1); 464 break; 465 case O_SKIPTO: 466 ksnprintf(SNPARGS(action2, 0), "SkipTo %d", 467 cmd->arg1); 468 break; 469 case O_PIPE: 470 ksnprintf(SNPARGS(action2, 0), "Pipe %d", 471 cmd->arg1); 472 break; 473 case O_QUEUE: 474 ksnprintf(SNPARGS(action2, 0), "Queue %d", 475 cmd->arg1); 476 break; 477 case O_FORWARD_IP: { 478 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 479 int len; 480 481 len = ksnprintf(SNPARGS(action2, 0), "Forward to %s", 482 inet_ntoa(sa->sa.sin_addr)); 483 if (sa->sa.sin_port) 484 ksnprintf(SNPARGS(action2, len), ":%d", 485 sa->sa.sin_port); 486 } 487 break; 488 default: 489 action = "UNKNOWN"; 490 break; 491 } 492 } 493 494 if (hlen == 0) { /* non-ip */ 495 ksnprintf(SNPARGS(proto, 0), "MAC"); 496 } else { 497 struct ip *ip = mtod(m, struct ip *); 498 /* these three are all aliases to the same thing */ 499 struct icmp *const icmp = L3HDR(struct icmp, ip); 500 struct tcphdr *const tcp = (struct tcphdr *)icmp; 501 struct udphdr *const udp = (struct udphdr *)icmp; 502 503 int ip_off, offset, ip_len; 504 505 int len; 506 507 if (eh != NULL) { /* layer 2 packets are as on the wire */ 508 ip_off = ntohs(ip->ip_off); 509 ip_len = ntohs(ip->ip_len); 510 } else { 511 ip_off = ip->ip_off; 512 ip_len = ip->ip_len; 513 } 514 offset = ip_off & IP_OFFMASK; 515 switch (ip->ip_p) { 516 case IPPROTO_TCP: 517 len = ksnprintf(SNPARGS(proto, 0), "TCP %s", 518 inet_ntoa(ip->ip_src)); 519 if (offset == 0) 520 ksnprintf(SNPARGS(proto, len), ":%d %s:%d", 521 ntohs(tcp->th_sport), 522 inet_ntoa(ip->ip_dst), 523 ntohs(tcp->th_dport)); 524 else 525 ksnprintf(SNPARGS(proto, len), " %s", 526 inet_ntoa(ip->ip_dst)); 527 break; 528 529 case IPPROTO_UDP: 530 len = ksnprintf(SNPARGS(proto, 0), "UDP %s", 531 inet_ntoa(ip->ip_src)); 532 if (offset == 0) 533 ksnprintf(SNPARGS(proto, len), ":%d %s:%d", 534 ntohs(udp->uh_sport), 535 inet_ntoa(ip->ip_dst), 536 ntohs(udp->uh_dport)); 537 else 538 ksnprintf(SNPARGS(proto, len), " %s", 539 inet_ntoa(ip->ip_dst)); 540 break; 541 542 case IPPROTO_ICMP: 543 if (offset == 0) 544 len = ksnprintf(SNPARGS(proto, 0), 545 "ICMP:%u.%u ", 546 icmp->icmp_type, icmp->icmp_code); 547 else 548 len = ksnprintf(SNPARGS(proto, 0), "ICMP "); 549 len += ksnprintf(SNPARGS(proto, len), "%s", 550 inet_ntoa(ip->ip_src)); 551 ksnprintf(SNPARGS(proto, len), " %s", 552 inet_ntoa(ip->ip_dst)); 553 break; 554 555 default: 556 len = ksnprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 557 inet_ntoa(ip->ip_src)); 558 ksnprintf(SNPARGS(proto, len), " %s", 559 inet_ntoa(ip->ip_dst)); 560 break; 561 } 562 563 if (ip_off & (IP_MF | IP_OFFMASK)) 564 ksnprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 565 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 566 offset << 3, 567 (ip_off & IP_MF) ? "+" : ""); 568 } 569 if (oif || m->m_pkthdr.rcvif) 570 log(LOG_SECURITY | LOG_INFO, 571 "ipfw: %d %s %s %s via %s%s\n", 572 f ? f->rulenum : -1, 573 action, proto, oif ? "out" : "in", 574 oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 575 fragment); 576 else 577 log(LOG_SECURITY | LOG_INFO, 578 "ipfw: %d %s %s [no if info]%s\n", 579 f ? f->rulenum : -1, 580 action, proto, fragment); 581 if (limit_reached) 582 log(LOG_SECURITY | LOG_NOTICE, 583 "ipfw: limit %d reached on entry %d\n", 584 limit_reached, f ? f->rulenum : -1); 585 } 586 587 /* 588 * IMPORTANT: the hash function for dynamic rules must be commutative 589 * in source and destination (ip,port), because rules are bidirectional 590 * and we want to find both in the same bucket. 591 */ 592 static __inline int 593 hash_packet(struct ipfw_flow_id *id) 594 { 595 u_int32_t i; 596 597 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 598 i &= (curr_dyn_buckets - 1); 599 return i; 600 } 601 602 /** 603 * unlink a dynamic rule from a chain. prev is a pointer to 604 * the previous one, q is a pointer to the rule to delete, 605 * head is a pointer to the head of the queue. 606 * Modifies q and potentially also head. 607 */ 608 #define UNLINK_DYN_RULE(prev, head, q) { \ 609 ipfw_dyn_rule *old_q = q; \ 610 \ 611 /* remove a refcount to the parent */ \ 612 if (q->dyn_type == O_LIMIT) \ 613 q->parent->count--; \ 614 DEB(kprintf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \ 615 (q->id.src_ip), (q->id.src_port), \ 616 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 617 if (prev != NULL) \ 618 prev->next = q = q->next; \ 619 else \ 620 head = q = q->next; \ 621 dyn_count--; \ 622 kfree(old_q, M_IPFW); } 623 624 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 625 626 /** 627 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 628 * 629 * If keep_me == NULL, rules are deleted even if not expired, 630 * otherwise only expired rules are removed. 631 * 632 * The value of the second parameter is also used to point to identify 633 * a rule we absolutely do not want to remove (e.g. because we are 634 * holding a reference to it -- this is the case with O_LIMIT_PARENT 635 * rules). The pointer is only used for comparison, so any non-null 636 * value will do. 637 */ 638 static void 639 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 640 { 641 static u_int32_t last_remove = 0; 642 643 #define FORCE (keep_me == NULL) 644 645 ipfw_dyn_rule *prev, *q; 646 int i, pass = 0, max_pass = 0; 647 648 if (ipfw_dyn_v == NULL || dyn_count == 0) 649 return; 650 /* do not expire more than once per second, it is useless */ 651 if (!FORCE && last_remove == time_second) 652 return; 653 last_remove = time_second; 654 655 /* 656 * because O_LIMIT refer to parent rules, during the first pass only 657 * remove child and mark any pending LIMIT_PARENT, and remove 658 * them in a second pass. 659 */ 660 next_pass: 661 for (i = 0 ; i < curr_dyn_buckets ; i++) { 662 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 663 /* 664 * Logic can become complex here, so we split tests. 665 */ 666 if (q == keep_me) 667 goto next; 668 if (rule != NULL && rule != q->rule) 669 goto next; /* not the one we are looking for */ 670 if (q->dyn_type == O_LIMIT_PARENT) { 671 /* 672 * handle parent in the second pass, 673 * record we need one. 674 */ 675 max_pass = 1; 676 if (pass == 0) 677 goto next; 678 if (FORCE && q->count != 0 ) { 679 /* XXX should not happen! */ 680 kprintf( "OUCH! cannot remove rule," 681 " count %d\n", q->count); 682 } 683 } else { 684 if (!FORCE && 685 !TIME_LEQ( q->expire, time_second )) 686 goto next; 687 } 688 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 689 continue; 690 next: 691 prev=q; 692 q=q->next; 693 } 694 } 695 if (pass++ < max_pass) 696 goto next_pass; 697 } 698 699 700 /** 701 * lookup a dynamic rule. 702 */ 703 static ipfw_dyn_rule * 704 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 705 struct tcphdr *tcp) 706 { 707 /* 708 * stateful ipfw extensions. 709 * Lookup into dynamic session queue 710 */ 711 #define MATCH_REVERSE 0 712 #define MATCH_FORWARD 1 713 #define MATCH_NONE 2 714 #define MATCH_UNKNOWN 3 715 int i, dir = MATCH_NONE; 716 ipfw_dyn_rule *prev, *q=NULL; 717 718 if (ipfw_dyn_v == NULL) 719 goto done; /* not found */ 720 i = hash_packet( pkt ); 721 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 722 if (q->dyn_type == O_LIMIT_PARENT) 723 goto next; 724 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 725 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 726 continue; 727 } 728 if ( pkt->proto == q->id.proto) { 729 if (pkt->src_ip == q->id.src_ip && 730 pkt->dst_ip == q->id.dst_ip && 731 pkt->src_port == q->id.src_port && 732 pkt->dst_port == q->id.dst_port ) { 733 dir = MATCH_FORWARD; 734 break; 735 } 736 if (pkt->src_ip == q->id.dst_ip && 737 pkt->dst_ip == q->id.src_ip && 738 pkt->src_port == q->id.dst_port && 739 pkt->dst_port == q->id.src_port ) { 740 dir = MATCH_REVERSE; 741 break; 742 } 743 } 744 next: 745 prev = q; 746 q = q->next; 747 } 748 if (q == NULL) 749 goto done; /* q = NULL, not found */ 750 751 if ( prev != NULL) { /* found and not in front */ 752 prev->next = q->next; 753 q->next = ipfw_dyn_v[i]; 754 ipfw_dyn_v[i] = q; 755 } 756 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 757 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 758 759 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 760 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 761 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 762 switch (q->state) { 763 case TH_SYN: /* opening */ 764 q->expire = time_second + dyn_syn_lifetime; 765 break; 766 767 case BOTH_SYN: /* move to established */ 768 case BOTH_SYN | TH_FIN : /* one side tries to close */ 769 case BOTH_SYN | (TH_FIN << 8) : 770 if (tcp) { 771 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 772 u_int32_t ack = ntohl(tcp->th_ack); 773 if (dir == MATCH_FORWARD) { 774 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 775 q->ack_fwd = ack; 776 else { /* ignore out-of-sequence */ 777 break; 778 } 779 } else { 780 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 781 q->ack_rev = ack; 782 else { /* ignore out-of-sequence */ 783 break; 784 } 785 } 786 } 787 q->expire = time_second + dyn_ack_lifetime; 788 break; 789 790 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 791 if (dyn_fin_lifetime >= dyn_keepalive_period) 792 dyn_fin_lifetime = dyn_keepalive_period - 1; 793 q->expire = time_second + dyn_fin_lifetime; 794 break; 795 796 default: 797 #if 0 798 /* 799 * reset or some invalid combination, but can also 800 * occur if we use keep-state the wrong way. 801 */ 802 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 803 kprintf("invalid state: 0x%x\n", q->state); 804 #endif 805 if (dyn_rst_lifetime >= dyn_keepalive_period) 806 dyn_rst_lifetime = dyn_keepalive_period - 1; 807 q->expire = time_second + dyn_rst_lifetime; 808 break; 809 } 810 } else if (pkt->proto == IPPROTO_UDP) { 811 q->expire = time_second + dyn_udp_lifetime; 812 } else { 813 /* other protocols */ 814 q->expire = time_second + dyn_short_lifetime; 815 } 816 done: 817 if (match_direction) 818 *match_direction = dir; 819 return q; 820 } 821 822 static void 823 realloc_dynamic_table(void) 824 { 825 /* 826 * Try reallocation, make sure we have a power of 2 and do 827 * not allow more than 64k entries. In case of overflow, 828 * default to 1024. 829 */ 830 831 if (dyn_buckets > 65536) 832 dyn_buckets = 1024; 833 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 834 dyn_buckets = curr_dyn_buckets; /* reset */ 835 return; 836 } 837 curr_dyn_buckets = dyn_buckets; 838 if (ipfw_dyn_v != NULL) 839 kfree(ipfw_dyn_v, M_IPFW); 840 for (;;) { 841 ipfw_dyn_v = kmalloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 842 M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO); 843 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 844 break; 845 curr_dyn_buckets /= 2; 846 } 847 } 848 849 /** 850 * Install state of type 'type' for a dynamic session. 851 * The hash table contains two type of rules: 852 * - regular rules (O_KEEP_STATE) 853 * - rules for sessions with limited number of sess per user 854 * (O_LIMIT). When they are created, the parent is 855 * increased by 1, and decreased on delete. In this case, 856 * the third parameter is the parent rule and not the chain. 857 * - "parent" rules for the above (O_LIMIT_PARENT). 858 */ 859 static ipfw_dyn_rule * 860 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 861 { 862 ipfw_dyn_rule *r; 863 int i; 864 865 if (ipfw_dyn_v == NULL || 866 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 867 realloc_dynamic_table(); 868 if (ipfw_dyn_v == NULL) 869 return NULL; /* failed ! */ 870 } 871 i = hash_packet(id); 872 873 r = kmalloc(sizeof *r, M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO); 874 if (r == NULL) { 875 kprintf ("sorry cannot allocate state\n"); 876 return NULL; 877 } 878 879 /* increase refcount on parent, and set pointer */ 880 if (dyn_type == O_LIMIT) { 881 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 882 if ( parent->dyn_type != O_LIMIT_PARENT) 883 panic("invalid parent"); 884 parent->count++; 885 r->parent = parent; 886 rule = parent->rule; 887 } 888 889 r->id = *id; 890 r->expire = time_second + dyn_syn_lifetime; 891 r->rule = rule; 892 r->dyn_type = dyn_type; 893 r->pcnt = r->bcnt = 0; 894 r->count = 0; 895 896 r->bucket = i; 897 r->next = ipfw_dyn_v[i]; 898 ipfw_dyn_v[i] = r; 899 dyn_count++; 900 DEB(kprintf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 901 dyn_type, 902 (r->id.src_ip), (r->id.src_port), 903 (r->id.dst_ip), (r->id.dst_port), 904 dyn_count ); ) 905 return r; 906 } 907 908 /** 909 * lookup dynamic parent rule using pkt and rule as search keys. 910 * If the lookup fails, then install one. 911 */ 912 static ipfw_dyn_rule * 913 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 914 { 915 ipfw_dyn_rule *q; 916 int i; 917 918 if (ipfw_dyn_v) { 919 i = hash_packet( pkt ); 920 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 921 if (q->dyn_type == O_LIMIT_PARENT && 922 rule== q->rule && 923 pkt->proto == q->id.proto && 924 pkt->src_ip == q->id.src_ip && 925 pkt->dst_ip == q->id.dst_ip && 926 pkt->src_port == q->id.src_port && 927 pkt->dst_port == q->id.dst_port) { 928 q->expire = time_second + dyn_short_lifetime; 929 DEB(kprintf("lookup_dyn_parent found 0x%p\n",q);) 930 return q; 931 } 932 } 933 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 934 } 935 936 /** 937 * Install dynamic state for rule type cmd->o.opcode 938 * 939 * Returns 1 (failure) if state is not installed because of errors or because 940 * session limitations are enforced. 941 */ 942 static int 943 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 944 struct ip_fw_args *args) 945 { 946 static int last_log; 947 948 ipfw_dyn_rule *q; 949 950 DEB(kprintf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", 951 cmd->o.opcode, 952 (args->f_id.src_ip), (args->f_id.src_port), 953 (args->f_id.dst_ip), (args->f_id.dst_port) );) 954 955 q = lookup_dyn_rule(&args->f_id, NULL, NULL); 956 957 if (q != NULL) { /* should never occur */ 958 if (last_log != time_second) { 959 last_log = time_second; 960 kprintf(" install_state: entry already present, done\n"); 961 } 962 return 0; 963 } 964 965 if (dyn_count >= dyn_max) 966 /* 967 * Run out of slots, try to remove any expired rule. 968 */ 969 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 970 971 if (dyn_count >= dyn_max) { 972 if (last_log != time_second) { 973 last_log = time_second; 974 kprintf("install_state: Too many dynamic rules\n"); 975 } 976 return 1; /* cannot install, notify caller */ 977 } 978 979 switch (cmd->o.opcode) { 980 case O_KEEP_STATE: /* bidir rule */ 981 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 982 break; 983 984 case O_LIMIT: /* limit number of sessions */ 985 { 986 u_int16_t limit_mask = cmd->limit_mask; 987 struct ipfw_flow_id id; 988 ipfw_dyn_rule *parent; 989 990 DEB(kprintf("installing dyn-limit rule %d\n", cmd->conn_limit);) 991 992 id.dst_ip = id.src_ip = 0; 993 id.dst_port = id.src_port = 0; 994 id.proto = args->f_id.proto; 995 996 if (limit_mask & DYN_SRC_ADDR) 997 id.src_ip = args->f_id.src_ip; 998 if (limit_mask & DYN_DST_ADDR) 999 id.dst_ip = args->f_id.dst_ip; 1000 if (limit_mask & DYN_SRC_PORT) 1001 id.src_port = args->f_id.src_port; 1002 if (limit_mask & DYN_DST_PORT) 1003 id.dst_port = args->f_id.dst_port; 1004 parent = lookup_dyn_parent(&id, rule); 1005 if (parent == NULL) { 1006 kprintf("add parent failed\n"); 1007 return 1; 1008 } 1009 if (parent->count >= cmd->conn_limit) { 1010 /* 1011 * See if we can remove some expired rule. 1012 */ 1013 remove_dyn_rule(rule, parent); 1014 if (parent->count >= cmd->conn_limit) { 1015 if (fw_verbose && last_log != time_second) { 1016 last_log = time_second; 1017 log(LOG_SECURITY | LOG_DEBUG, 1018 "drop session, too many entries\n"); 1019 } 1020 return 1; 1021 } 1022 } 1023 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1024 } 1025 break; 1026 default: 1027 kprintf("unknown dynamic rule type %u\n", cmd->o.opcode); 1028 return 1; 1029 } 1030 lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1031 return 0; 1032 } 1033 1034 /* 1035 * Transmit a TCP packet, containing either a RST or a keepalive. 1036 * When flags & TH_RST, we are sending a RST packet, because of a 1037 * "reset" action matched the packet. 1038 * Otherwise we are sending a keepalive, and flags & TH_ 1039 */ 1040 static void 1041 send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1042 { 1043 struct mbuf *m; 1044 struct ip *ip; 1045 struct tcphdr *tcp; 1046 struct route sro; /* fake route */ 1047 1048 MGETHDR(m, MB_DONTWAIT, MT_HEADER); 1049 if (m == 0) 1050 return; 1051 m->m_pkthdr.rcvif = (struct ifnet *)0; 1052 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1053 m->m_data += max_linkhdr; 1054 1055 ip = mtod(m, struct ip *); 1056 bzero(ip, m->m_len); 1057 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1058 ip->ip_p = IPPROTO_TCP; 1059 tcp->th_off = 5; 1060 /* 1061 * Assume we are sending a RST (or a keepalive in the reverse 1062 * direction), swap src and destination addresses and ports. 1063 */ 1064 ip->ip_src.s_addr = htonl(id->dst_ip); 1065 ip->ip_dst.s_addr = htonl(id->src_ip); 1066 tcp->th_sport = htons(id->dst_port); 1067 tcp->th_dport = htons(id->src_port); 1068 if (flags & TH_RST) { /* we are sending a RST */ 1069 if (flags & TH_ACK) { 1070 tcp->th_seq = htonl(ack); 1071 tcp->th_ack = htonl(0); 1072 tcp->th_flags = TH_RST; 1073 } else { 1074 if (flags & TH_SYN) 1075 seq++; 1076 tcp->th_seq = htonl(0); 1077 tcp->th_ack = htonl(seq); 1078 tcp->th_flags = TH_RST | TH_ACK; 1079 } 1080 } else { 1081 /* 1082 * We are sending a keepalive. flags & TH_SYN determines 1083 * the direction, forward if set, reverse if clear. 1084 * NOTE: seq and ack are always assumed to be correct 1085 * as set by the caller. This may be confusing... 1086 */ 1087 if (flags & TH_SYN) { 1088 /* 1089 * we have to rewrite the correct addresses! 1090 */ 1091 ip->ip_dst.s_addr = htonl(id->dst_ip); 1092 ip->ip_src.s_addr = htonl(id->src_ip); 1093 tcp->th_dport = htons(id->dst_port); 1094 tcp->th_sport = htons(id->src_port); 1095 } 1096 tcp->th_seq = htonl(seq); 1097 tcp->th_ack = htonl(ack); 1098 tcp->th_flags = TH_ACK; 1099 } 1100 /* 1101 * set ip_len to the payload size so we can compute 1102 * the tcp checksum on the pseudoheader 1103 * XXX check this, could save a couple of words ? 1104 */ 1105 ip->ip_len = htons(sizeof(struct tcphdr)); 1106 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1107 /* 1108 * now fill fields left out earlier 1109 */ 1110 ip->ip_ttl = ip_defttl; 1111 ip->ip_len = m->m_pkthdr.len; 1112 bzero (&sro, sizeof (sro)); 1113 ip_rtaddr(ip->ip_dst, &sro); 1114 m->m_pkthdr.fw_flags |= IPFW_MBUF_SKIP_FIREWALL; 1115 ip_output(m, NULL, &sro, 0, NULL, NULL); 1116 if (sro.ro_rt) 1117 RTFREE(sro.ro_rt); 1118 } 1119 1120 /* 1121 * sends a reject message, consuming the mbuf passed as an argument. 1122 */ 1123 static void 1124 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1125 { 1126 1127 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1128 /* We need the IP header in host order for icmp_error(). */ 1129 if (args->eh != NULL) { 1130 struct ip *ip = mtod(args->m, struct ip *); 1131 ip->ip_len = ntohs(ip->ip_len); 1132 ip->ip_off = ntohs(ip->ip_off); 1133 } 1134 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1135 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1136 struct tcphdr *const tcp = 1137 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1138 if ( (tcp->th_flags & TH_RST) == 0) 1139 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1140 ntohl(tcp->th_ack), 1141 tcp->th_flags | TH_RST); 1142 m_freem(args->m); 1143 } else 1144 m_freem(args->m); 1145 args->m = NULL; 1146 } 1147 1148 /** 1149 * 1150 * Given an ip_fw *, lookup_next_rule will return a pointer 1151 * to the next rule, which can be either the jump 1152 * target (for skipto instructions) or the next one in the list (in 1153 * all other cases including a missing jump target). 1154 * The result is also written in the "next_rule" field of the rule. 1155 * Backward jumps are not allowed, so start looking from the next 1156 * rule... 1157 * 1158 * This never returns NULL -- in case we do not have an exact match, 1159 * the next rule is returned. When the ruleset is changed, 1160 * pointers are flushed so we are always correct. 1161 */ 1162 1163 static struct ip_fw * 1164 lookup_next_rule(struct ip_fw *me) 1165 { 1166 struct ip_fw *rule = NULL; 1167 ipfw_insn *cmd; 1168 1169 /* look for action, in case it is a skipto */ 1170 cmd = ACTION_PTR(me); 1171 if (cmd->opcode == O_LOG) 1172 cmd += F_LEN(cmd); 1173 if ( cmd->opcode == O_SKIPTO ) 1174 for (rule = me->next; rule ; rule = rule->next) 1175 if (rule->rulenum >= cmd->arg1) 1176 break; 1177 if (rule == NULL) /* failure or not a skipto */ 1178 rule = me->next; 1179 me->next_rule = rule; 1180 return rule; 1181 } 1182 1183 /* 1184 * The main check routine for the firewall. 1185 * 1186 * All arguments are in args so we can modify them and return them 1187 * back to the caller. 1188 * 1189 * Parameters: 1190 * 1191 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1192 * Starts with the IP header. 1193 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1194 * args->oif Outgoing interface, or NULL if packet is incoming. 1195 * The incoming interface is in the mbuf. (in) 1196 * 1197 * args->rule Pointer to the last matching rule (in/out) 1198 * args->next_hop Socket we are forwarding to (out). 1199 * args->f_id Addresses grabbed from the packet (out) 1200 * 1201 * Return value: 1202 * 1203 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1204 * 0 The packet is to be accepted and routed normally OR 1205 * the packet was denied/rejected and has been dropped; 1206 * in the latter case, *m is equal to NULL upon return. 1207 * port Divert the packet to port, with these caveats: 1208 * 1209 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1210 * of diverting it (ie, 'ipfw tee'). 1211 * 1212 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1213 * 16 bits as a dummynet pipe number instead of diverting 1214 */ 1215 1216 static int 1217 ipfw_chk(struct ip_fw_args *args) 1218 { 1219 /* 1220 * Local variables hold state during the processing of a packet. 1221 * 1222 * IMPORTANT NOTE: to speed up the processing of rules, there 1223 * are some assumption on the values of the variables, which 1224 * are documented here. Should you change them, please check 1225 * the implementation of the various instructions to make sure 1226 * that they still work. 1227 * 1228 * args->eh The MAC header. It is non-null for a layer2 1229 * packet, it is NULL for a layer-3 packet. 1230 * 1231 * m | args->m Pointer to the mbuf, as received from the caller. 1232 * It may change if ipfw_chk() does an m_pullup, or if it 1233 * consumes the packet because it calls send_reject(). 1234 * XXX This has to change, so that ipfw_chk() never modifies 1235 * or consumes the buffer. 1236 * ip is simply an alias of the value of m, and it is kept 1237 * in sync with it (the packet is supposed to start with 1238 * the ip header). 1239 */ 1240 struct mbuf *m = args->m; 1241 struct ip *ip = mtod(m, struct ip *); 1242 1243 /* 1244 * oif | args->oif If NULL, ipfw_chk has been called on the 1245 * inbound path (ether_input, ip_input). 1246 * If non-NULL, ipfw_chk has been called on the outbound path 1247 * (ether_output, ip_output). 1248 */ 1249 struct ifnet *oif = args->oif; 1250 1251 struct ip_fw *f = NULL; /* matching rule */ 1252 int retval = 0; 1253 struct m_tag *mtag; 1254 1255 /* 1256 * hlen The length of the IPv4 header. 1257 * hlen >0 means we have an IPv4 packet. 1258 */ 1259 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1260 1261 /* 1262 * offset The offset of a fragment. offset != 0 means that 1263 * we have a fragment at this offset of an IPv4 packet. 1264 * offset == 0 means that (if this is an IPv4 packet) 1265 * this is the first or only fragment. 1266 */ 1267 u_short offset = 0; 1268 1269 /* 1270 * Local copies of addresses. They are only valid if we have 1271 * an IP packet. 1272 * 1273 * proto The protocol. Set to 0 for non-ip packets, 1274 * or to the protocol read from the packet otherwise. 1275 * proto != 0 means that we have an IPv4 packet. 1276 * 1277 * src_port, dst_port port numbers, in HOST format. Only 1278 * valid for TCP and UDP packets. 1279 * 1280 * src_ip, dst_ip ip addresses, in NETWORK format. 1281 * Only valid for IPv4 packets. 1282 */ 1283 u_int8_t proto; 1284 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1285 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1286 u_int16_t ip_len=0; 1287 int dyn_dir = MATCH_UNKNOWN; 1288 ipfw_dyn_rule *q = NULL; 1289 1290 if (m->m_pkthdr.fw_flags & IPFW_MBUF_SKIP_FIREWALL) 1291 return 0; /* accept */ 1292 /* 1293 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1294 * MATCH_NONE when checked and not matched (q = NULL), 1295 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1296 */ 1297 1298 if (args->eh == NULL || /* layer 3 packet */ 1299 ( m->m_pkthdr.len >= sizeof(struct ip) && 1300 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1301 hlen = ip->ip_hl << 2; 1302 1303 /* 1304 * Collect parameters into local variables for faster matching. 1305 */ 1306 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1307 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1308 goto after_ip_checks; 1309 } 1310 1311 proto = args->f_id.proto = ip->ip_p; 1312 src_ip = ip->ip_src; 1313 dst_ip = ip->ip_dst; 1314 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1315 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1316 ip_len = ntohs(ip->ip_len); 1317 } else { 1318 offset = ip->ip_off & IP_OFFMASK; 1319 ip_len = ip->ip_len; 1320 } 1321 1322 #define PULLUP_TO(len) \ 1323 do { \ 1324 if ((m)->m_len < (len)) { \ 1325 args->m = m = m_pullup(m, (len)); \ 1326 if (m == 0) \ 1327 goto pullup_failed; \ 1328 ip = mtod(m, struct ip *); \ 1329 } \ 1330 } while (0) 1331 1332 if (offset == 0) { 1333 switch (proto) { 1334 case IPPROTO_TCP: 1335 { 1336 struct tcphdr *tcp; 1337 1338 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1339 tcp = L3HDR(struct tcphdr, ip); 1340 dst_port = tcp->th_dport; 1341 src_port = tcp->th_sport; 1342 args->f_id.flags = tcp->th_flags; 1343 } 1344 break; 1345 1346 case IPPROTO_UDP: 1347 { 1348 struct udphdr *udp; 1349 1350 PULLUP_TO(hlen + sizeof(struct udphdr)); 1351 udp = L3HDR(struct udphdr, ip); 1352 dst_port = udp->uh_dport; 1353 src_port = udp->uh_sport; 1354 } 1355 break; 1356 1357 case IPPROTO_ICMP: 1358 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1359 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1360 break; 1361 1362 default: 1363 break; 1364 } 1365 #undef PULLUP_TO 1366 } 1367 1368 args->f_id.src_ip = ntohl(src_ip.s_addr); 1369 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1370 args->f_id.src_port = src_port = ntohs(src_port); 1371 args->f_id.dst_port = dst_port = ntohs(dst_port); 1372 1373 after_ip_checks: 1374 if (args->rule) { 1375 /* 1376 * Packet has already been tagged. Look for the next rule 1377 * to restart processing. 1378 * 1379 * If fw_one_pass != 0 then just accept it. 1380 * XXX should not happen here, but optimized out in 1381 * the caller. 1382 */ 1383 if (fw_one_pass) 1384 return 0; 1385 1386 f = args->rule->next_rule; 1387 if (f == NULL) 1388 f = lookup_next_rule(args->rule); 1389 } else { 1390 /* 1391 * Find the starting rule. It can be either the first 1392 * one, or the one after divert_rule if asked so. 1393 */ 1394 int skipto; 1395 1396 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 1397 if (mtag != NULL) 1398 skipto = *(u_int16_t *)m_tag_data(mtag); 1399 else 1400 skipto = 0; 1401 1402 f = layer3_chain; 1403 if (args->eh == NULL && skipto != 0) { 1404 if (skipto >= IPFW_DEFAULT_RULE) 1405 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1406 while (f && f->rulenum <= skipto) 1407 f = f->next; 1408 if (f == NULL) /* drop packet */ 1409 return(IP_FW_PORT_DENY_FLAG); 1410 } 1411 } 1412 if ((mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL)) != NULL) 1413 m_tag_delete(m, mtag); 1414 1415 /* 1416 * Now scan the rules, and parse microinstructions for each rule. 1417 */ 1418 for (; f; f = f->next) { 1419 int l, cmdlen; 1420 ipfw_insn *cmd; 1421 int skip_or; /* skip rest of OR block */ 1422 1423 again: 1424 if (set_disable & (1 << f->set) ) 1425 continue; 1426 1427 skip_or = 0; 1428 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1429 l -= cmdlen, cmd += cmdlen) { 1430 int match; 1431 1432 /* 1433 * check_body is a jump target used when we find a 1434 * CHECK_STATE, and need to jump to the body of 1435 * the target rule. 1436 */ 1437 1438 check_body: 1439 cmdlen = F_LEN(cmd); 1440 /* 1441 * An OR block (insn_1 || .. || insn_n) has the 1442 * F_OR bit set in all but the last instruction. 1443 * The first match will set "skip_or", and cause 1444 * the following instructions to be skipped until 1445 * past the one with the F_OR bit clear. 1446 */ 1447 if (skip_or) { /* skip this instruction */ 1448 if ((cmd->len & F_OR) == 0) 1449 skip_or = 0; /* next one is good */ 1450 continue; 1451 } 1452 match = 0; /* set to 1 if we succeed */ 1453 1454 switch (cmd->opcode) { 1455 /* 1456 * The first set of opcodes compares the packet's 1457 * fields with some pattern, setting 'match' if a 1458 * match is found. At the end of the loop there is 1459 * logic to deal with F_NOT and F_OR flags associated 1460 * with the opcode. 1461 */ 1462 case O_NOP: 1463 match = 1; 1464 break; 1465 1466 case O_FORWARD_MAC: 1467 kprintf("ipfw: opcode %d unimplemented\n", 1468 cmd->opcode); 1469 break; 1470 1471 case O_GID: 1472 case O_UID: 1473 /* 1474 * We only check offset == 0 && proto != 0, 1475 * as this ensures that we have an IPv4 1476 * packet with the ports info. 1477 */ 1478 if (offset!=0) 1479 break; 1480 { 1481 struct inpcbinfo *pi; 1482 int wildcard; 1483 struct inpcb *pcb; 1484 1485 if (proto == IPPROTO_TCP) { 1486 wildcard = 0; 1487 pi = &tcbinfo[mycpu->gd_cpuid]; 1488 } else if (proto == IPPROTO_UDP) { 1489 wildcard = 1; 1490 pi = &udbinfo; 1491 } else 1492 break; 1493 1494 pcb = (oif) ? 1495 in_pcblookup_hash(pi, 1496 dst_ip, htons(dst_port), 1497 src_ip, htons(src_port), 1498 wildcard, oif) : 1499 in_pcblookup_hash(pi, 1500 src_ip, htons(src_port), 1501 dst_ip, htons(dst_port), 1502 wildcard, NULL); 1503 1504 if (pcb == NULL || pcb->inp_socket == NULL) 1505 break; 1506 #if defined(__DragonFly__) || (defined(__FreeBSD__) && __FreeBSD_version < 500034) 1507 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1508 #endif 1509 if (cmd->opcode == O_UID) { 1510 match = 1511 !socheckuid(pcb->inp_socket, 1512 (uid_t)((ipfw_insn_u32 *)cmd)->d[0]); 1513 } else { 1514 match = groupmember( 1515 (uid_t)((ipfw_insn_u32 *)cmd)->d[0], 1516 pcb->inp_socket->so_cred); 1517 } 1518 } 1519 break; 1520 1521 case O_RECV: 1522 match = iface_match(m->m_pkthdr.rcvif, 1523 (ipfw_insn_if *)cmd); 1524 break; 1525 1526 case O_XMIT: 1527 match = iface_match(oif, (ipfw_insn_if *)cmd); 1528 break; 1529 1530 case O_VIA: 1531 match = iface_match(oif ? oif : 1532 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1533 break; 1534 1535 case O_MACADDR2: 1536 if (args->eh != NULL) { /* have MAC header */ 1537 u_int32_t *want = (u_int32_t *) 1538 ((ipfw_insn_mac *)cmd)->addr; 1539 u_int32_t *mask = (u_int32_t *) 1540 ((ipfw_insn_mac *)cmd)->mask; 1541 u_int32_t *hdr = (u_int32_t *)args->eh; 1542 1543 match = 1544 ( want[0] == (hdr[0] & mask[0]) && 1545 want[1] == (hdr[1] & mask[1]) && 1546 want[2] == (hdr[2] & mask[2]) ); 1547 } 1548 break; 1549 1550 case O_MAC_TYPE: 1551 if (args->eh != NULL) { 1552 u_int16_t t = 1553 ntohs(args->eh->ether_type); 1554 u_int16_t *p = 1555 ((ipfw_insn_u16 *)cmd)->ports; 1556 int i; 1557 1558 for (i = cmdlen - 1; !match && i>0; 1559 i--, p += 2) 1560 match = (t>=p[0] && t<=p[1]); 1561 } 1562 break; 1563 1564 case O_FRAG: 1565 match = (hlen > 0 && offset != 0); 1566 break; 1567 1568 case O_IN: /* "out" is "not in" */ 1569 match = (oif == NULL); 1570 break; 1571 1572 case O_LAYER2: 1573 match = (args->eh != NULL); 1574 break; 1575 1576 case O_PROTO: 1577 /* 1578 * We do not allow an arg of 0 so the 1579 * check of "proto" only suffices. 1580 */ 1581 match = (proto == cmd->arg1); 1582 break; 1583 1584 case O_IP_SRC: 1585 match = (hlen > 0 && 1586 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1587 src_ip.s_addr); 1588 break; 1589 1590 case O_IP_SRC_MASK: 1591 match = (hlen > 0 && 1592 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1593 (src_ip.s_addr & 1594 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1595 break; 1596 1597 case O_IP_SRC_ME: 1598 if (hlen > 0) { 1599 struct ifnet *tif; 1600 1601 INADDR_TO_IFP(src_ip, tif); 1602 match = (tif != NULL); 1603 } 1604 break; 1605 1606 case O_IP_DST_SET: 1607 case O_IP_SRC_SET: 1608 if (hlen > 0) { 1609 u_int32_t *d = (u_int32_t *)(cmd+1); 1610 u_int32_t addr = 1611 cmd->opcode == O_IP_DST_SET ? 1612 args->f_id.dst_ip : 1613 args->f_id.src_ip; 1614 1615 if (addr < d[0]) 1616 break; 1617 addr -= d[0]; /* subtract base */ 1618 match = (addr < cmd->arg1) && 1619 ( d[ 1 + (addr>>5)] & 1620 (1<<(addr & 0x1f)) ); 1621 } 1622 break; 1623 1624 case O_IP_DST: 1625 match = (hlen > 0 && 1626 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1627 dst_ip.s_addr); 1628 break; 1629 1630 case O_IP_DST_MASK: 1631 match = (hlen > 0) && 1632 (((ipfw_insn_ip *)cmd)->addr.s_addr == 1633 (dst_ip.s_addr & 1634 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1635 break; 1636 1637 case O_IP_DST_ME: 1638 if (hlen > 0) { 1639 struct ifnet *tif; 1640 1641 INADDR_TO_IFP(dst_ip, tif); 1642 match = (tif != NULL); 1643 } 1644 break; 1645 1646 case O_IP_SRCPORT: 1647 case O_IP_DSTPORT: 1648 /* 1649 * offset == 0 && proto != 0 is enough 1650 * to guarantee that we have an IPv4 1651 * packet with port info. 1652 */ 1653 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1654 && offset == 0) { 1655 u_int16_t x = 1656 (cmd->opcode == O_IP_SRCPORT) ? 1657 src_port : dst_port ; 1658 u_int16_t *p = 1659 ((ipfw_insn_u16 *)cmd)->ports; 1660 int i; 1661 1662 for (i = cmdlen - 1; !match && i>0; 1663 i--, p += 2) 1664 match = (x>=p[0] && x<=p[1]); 1665 } 1666 break; 1667 1668 case O_ICMPTYPE: 1669 match = (offset == 0 && proto==IPPROTO_ICMP && 1670 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1671 break; 1672 1673 case O_IPOPT: 1674 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1675 break; 1676 1677 case O_IPVER: 1678 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1679 break; 1680 1681 case O_IPTTL: 1682 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl); 1683 break; 1684 1685 case O_IPID: 1686 match = (hlen > 0 && 1687 cmd->arg1 == ntohs(ip->ip_id)); 1688 break; 1689 1690 case O_IPLEN: 1691 match = (hlen > 0 && cmd->arg1 == ip_len); 1692 break; 1693 1694 case O_IPPRECEDENCE: 1695 match = (hlen > 0 && 1696 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1697 break; 1698 1699 case O_IPTOS: 1700 match = (hlen > 0 && 1701 flags_match(cmd, ip->ip_tos)); 1702 break; 1703 1704 case O_TCPFLAGS: 1705 match = (proto == IPPROTO_TCP && offset == 0 && 1706 flags_match(cmd, 1707 L3HDR(struct tcphdr,ip)->th_flags)); 1708 break; 1709 1710 case O_TCPOPTS: 1711 match = (proto == IPPROTO_TCP && offset == 0 && 1712 tcpopts_match(ip, cmd)); 1713 break; 1714 1715 case O_TCPSEQ: 1716 match = (proto == IPPROTO_TCP && offset == 0 && 1717 ((ipfw_insn_u32 *)cmd)->d[0] == 1718 L3HDR(struct tcphdr,ip)->th_seq); 1719 break; 1720 1721 case O_TCPACK: 1722 match = (proto == IPPROTO_TCP && offset == 0 && 1723 ((ipfw_insn_u32 *)cmd)->d[0] == 1724 L3HDR(struct tcphdr,ip)->th_ack); 1725 break; 1726 1727 case O_TCPWIN: 1728 match = (proto == IPPROTO_TCP && offset == 0 && 1729 cmd->arg1 == 1730 L3HDR(struct tcphdr,ip)->th_win); 1731 break; 1732 1733 case O_ESTAB: 1734 /* reject packets which have SYN only */ 1735 /* XXX should i also check for TH_ACK ? */ 1736 match = (proto == IPPROTO_TCP && offset == 0 && 1737 (L3HDR(struct tcphdr,ip)->th_flags & 1738 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1739 break; 1740 1741 case O_LOG: 1742 if (fw_verbose) 1743 ipfw_log(f, hlen, args->eh, m, oif); 1744 match = 1; 1745 break; 1746 1747 case O_PROB: 1748 match = (krandom() < 1749 ((ipfw_insn_u32 *)cmd)->d[0]); 1750 break; 1751 1752 /* 1753 * The second set of opcodes represents 'actions', 1754 * i.e. the terminal part of a rule once the packet 1755 * matches all previous patterns. 1756 * Typically there is only one action for each rule, 1757 * and the opcode is stored at the end of the rule 1758 * (but there are exceptions -- see below). 1759 * 1760 * In general, here we set retval and terminate the 1761 * outer loop (would be a 'break 3' in some language, 1762 * but we need to do a 'goto done'). 1763 * 1764 * Exceptions: 1765 * O_COUNT and O_SKIPTO actions: 1766 * instead of terminating, we jump to the next rule 1767 * ('goto next_rule', equivalent to a 'break 2'), 1768 * or to the SKIPTO target ('goto again' after 1769 * having set f, cmd and l), respectively. 1770 * 1771 * O_LIMIT and O_KEEP_STATE: these opcodes are 1772 * not real 'actions', and are stored right 1773 * before the 'action' part of the rule. 1774 * These opcodes try to install an entry in the 1775 * state tables; if successful, we continue with 1776 * the next opcode (match=1; break;), otherwise 1777 * the packet * must be dropped 1778 * ('goto done' after setting retval); 1779 * 1780 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1781 * cause a lookup of the state table, and a jump 1782 * to the 'action' part of the parent rule 1783 * ('goto check_body') if an entry is found, or 1784 * (CHECK_STATE only) a jump to the next rule if 1785 * the entry is not found ('goto next_rule'). 1786 * The result of the lookup is cached to make 1787 * further instances of these opcodes are 1788 * effectively NOPs. 1789 */ 1790 case O_LIMIT: 1791 case O_KEEP_STATE: 1792 if (install_state(f, 1793 (ipfw_insn_limit *)cmd, args)) { 1794 retval = IP_FW_PORT_DENY_FLAG; 1795 goto done; /* error/limit violation */ 1796 } 1797 match = 1; 1798 break; 1799 1800 case O_PROBE_STATE: 1801 case O_CHECK_STATE: 1802 /* 1803 * dynamic rules are checked at the first 1804 * keep-state or check-state occurrence, 1805 * with the result being stored in dyn_dir. 1806 * The compiler introduces a PROBE_STATE 1807 * instruction for us when we have a 1808 * KEEP_STATE (because PROBE_STATE needs 1809 * to be run first). 1810 */ 1811 if (dyn_dir == MATCH_UNKNOWN && 1812 (q = lookup_dyn_rule(&args->f_id, 1813 &dyn_dir, proto == IPPROTO_TCP ? 1814 L3HDR(struct tcphdr, ip) : NULL)) 1815 != NULL) { 1816 /* 1817 * Found dynamic entry, update stats 1818 * and jump to the 'action' part of 1819 * the parent rule. 1820 */ 1821 q->pcnt++; 1822 q->bcnt += ip_len; 1823 f = q->rule; 1824 cmd = ACTION_PTR(f); 1825 l = f->cmd_len - f->act_ofs; 1826 goto check_body; 1827 } 1828 /* 1829 * Dynamic entry not found. If CHECK_STATE, 1830 * skip to next rule, if PROBE_STATE just 1831 * ignore and continue with next opcode. 1832 */ 1833 if (cmd->opcode == O_CHECK_STATE) 1834 goto next_rule; 1835 match = 1; 1836 break; 1837 1838 case O_ACCEPT: 1839 retval = 0; /* accept */ 1840 goto done; 1841 1842 case O_PIPE: 1843 case O_QUEUE: 1844 args->rule = f; /* report matching rule */ 1845 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 1846 goto done; 1847 1848 case O_DIVERT: 1849 case O_TEE: 1850 if (args->eh) /* not on layer 2 */ 1851 break; 1852 1853 mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, 1854 sizeof(u_int16_t), MB_DONTWAIT); 1855 if (mtag == NULL) { 1856 retval = IP_FW_PORT_DENY_FLAG; 1857 goto done; 1858 } 1859 *(u_int16_t *)m_tag_data(mtag) = f->rulenum; 1860 m_tag_prepend(m, mtag); 1861 retval = (cmd->opcode == O_DIVERT) ? 1862 cmd->arg1 : 1863 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 1864 goto done; 1865 1866 case O_COUNT: 1867 case O_SKIPTO: 1868 f->pcnt++; /* update stats */ 1869 f->bcnt += ip_len; 1870 f->timestamp = time_second; 1871 if (cmd->opcode == O_COUNT) 1872 goto next_rule; 1873 /* handle skipto */ 1874 if (f->next_rule == NULL) 1875 lookup_next_rule(f); 1876 f = f->next_rule; 1877 goto again; 1878 1879 case O_REJECT: 1880 /* 1881 * Drop the packet and send a reject notice 1882 * if the packet is not ICMP (or is an ICMP 1883 * query), and it is not multicast/broadcast. 1884 */ 1885 if (hlen > 0 && 1886 (proto != IPPROTO_ICMP || 1887 is_icmp_query(ip)) && 1888 !(m->m_flags & (M_BCAST|M_MCAST)) && 1889 !IN_MULTICAST(ntohl(dst_ip.s_addr))) { 1890 send_reject(args, cmd->arg1, 1891 offset,ip_len); 1892 m = args->m; 1893 } 1894 /* FALLTHROUGH */ 1895 case O_DENY: 1896 retval = IP_FW_PORT_DENY_FLAG; 1897 goto done; 1898 1899 case O_FORWARD_IP: 1900 if (args->eh) /* not valid on layer2 pkts */ 1901 break; 1902 if (!q || dyn_dir == MATCH_FORWARD) 1903 args->next_hop = 1904 &((ipfw_insn_sa *)cmd)->sa; 1905 retval = 0; 1906 goto done; 1907 1908 default: 1909 panic("-- unknown opcode %d\n", cmd->opcode); 1910 } /* end of switch() on opcodes */ 1911 1912 if (cmd->len & F_NOT) 1913 match = !match; 1914 1915 if (match) { 1916 if (cmd->len & F_OR) 1917 skip_or = 1; 1918 } else { 1919 if (!(cmd->len & F_OR)) /* not an OR block, */ 1920 break; /* try next rule */ 1921 } 1922 1923 } /* end of inner for, scan opcodes */ 1924 1925 next_rule:; /* try next rule */ 1926 1927 } /* end of outer for, scan rules */ 1928 kprintf("+++ ipfw: ouch!, skip past end of rules, denying packet\n"); 1929 return(IP_FW_PORT_DENY_FLAG); 1930 1931 done: 1932 /* Update statistics */ 1933 f->pcnt++; 1934 f->bcnt += ip_len; 1935 f->timestamp = time_second; 1936 return retval; 1937 1938 pullup_failed: 1939 if (fw_verbose) 1940 kprintf("pullup failed\n"); 1941 return(IP_FW_PORT_DENY_FLAG); 1942 } 1943 1944 /* 1945 * When a rule is added/deleted, clear the next_rule pointers in all rules. 1946 * These will be reconstructed on the fly as packets are matched. 1947 * Must be called at splimp(). 1948 */ 1949 static void 1950 flush_rule_ptrs(void) 1951 { 1952 struct ip_fw *rule; 1953 1954 for (rule = layer3_chain; rule; rule = rule->next) 1955 rule->next_rule = NULL; 1956 } 1957 1958 /* 1959 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 1960 * pipe/queue, or to all of them (match == NULL). 1961 * Must be called at splimp(). 1962 */ 1963 void 1964 flush_pipe_ptrs(struct dn_flow_set *match) 1965 { 1966 struct ip_fw *rule; 1967 1968 for (rule = layer3_chain; rule; rule = rule->next) { 1969 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 1970 1971 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 1972 continue; 1973 if (match == NULL || cmd->pipe_ptr == match) 1974 cmd->pipe_ptr = NULL; 1975 } 1976 } 1977 1978 /* 1979 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 1980 * possibly create a rule number and add the rule to the list. 1981 * Update the rule_number in the input struct so the caller knows it as well. 1982 */ 1983 static int 1984 add_rule(struct ip_fw **head, struct ip_fw *input_rule) 1985 { 1986 struct ip_fw *rule, *f, *prev; 1987 int l = RULESIZE(input_rule); 1988 1989 if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 1990 return (EINVAL); 1991 1992 rule = kmalloc(l, M_IPFW, M_WAITOK | M_ZERO); 1993 1994 bcopy(input_rule, rule, l); 1995 1996 rule->next = NULL; 1997 rule->next_rule = NULL; 1998 1999 rule->pcnt = 0; 2000 rule->bcnt = 0; 2001 rule->timestamp = 0; 2002 2003 crit_enter(); 2004 2005 if (*head == NULL) { /* default rule */ 2006 *head = rule; 2007 goto done; 2008 } 2009 2010 /* 2011 * If rulenum is 0, find highest numbered rule before the 2012 * default rule, and add autoinc_step 2013 */ 2014 if (autoinc_step < 1) 2015 autoinc_step = 1; 2016 else if (autoinc_step > 1000) 2017 autoinc_step = 1000; 2018 if (rule->rulenum == 0) { 2019 /* 2020 * locate the highest numbered rule before default 2021 */ 2022 for (f = *head; f; f = f->next) { 2023 if (f->rulenum == IPFW_DEFAULT_RULE) 2024 break; 2025 rule->rulenum = f->rulenum; 2026 } 2027 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2028 rule->rulenum += autoinc_step; 2029 input_rule->rulenum = rule->rulenum; 2030 } 2031 2032 /* 2033 * Now insert the new rule in the right place in the sorted list. 2034 */ 2035 for (prev = NULL, f = *head; f; prev = f, f = f->next) { 2036 if (f->rulenum > rule->rulenum) { /* found the location */ 2037 if (prev) { 2038 rule->next = f; 2039 prev->next = rule; 2040 } else { /* head insert */ 2041 rule->next = *head; 2042 *head = rule; 2043 } 2044 break; 2045 } 2046 } 2047 flush_rule_ptrs(); 2048 done: 2049 static_count++; 2050 static_len += l; 2051 crit_exit(); 2052 DEB(kprintf("++ installed rule %d, static count now %d\n", 2053 rule->rulenum, static_count);) 2054 return (0); 2055 } 2056 2057 /** 2058 * Free storage associated with a static rule (including derived 2059 * dynamic rules). 2060 * The caller is in charge of clearing rule pointers to avoid 2061 * dangling pointers. 2062 * @return a pointer to the next entry. 2063 * Arguments are not checked, so they better be correct. 2064 * Must be called at splimp(). 2065 */ 2066 static struct ip_fw * 2067 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) 2068 { 2069 struct ip_fw *n; 2070 int l = RULESIZE(rule); 2071 2072 n = rule->next; 2073 remove_dyn_rule(rule, NULL /* force removal */); 2074 if (prev == NULL) 2075 *head = n; 2076 else 2077 prev->next = n; 2078 static_count--; 2079 static_len -= l; 2080 2081 if (DUMMYNET_LOADED) 2082 ip_dn_ruledel_ptr(rule); 2083 kfree(rule, M_IPFW); 2084 return n; 2085 } 2086 2087 /* 2088 * Deletes all rules from a chain (including the default rule 2089 * if the second argument is set). 2090 * Must be called at splimp(). 2091 */ 2092 static void 2093 free_chain(struct ip_fw **chain, int kill_default) 2094 { 2095 struct ip_fw *rule; 2096 2097 flush_rule_ptrs(); /* more efficient to do outside the loop */ 2098 2099 while ( (rule = *chain) != NULL && 2100 (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) 2101 delete_rule(chain, NULL, rule); 2102 } 2103 2104 /** 2105 * Remove all rules with given number, and also do set manipulation. 2106 * 2107 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2108 * the next 8 bits are the new set, the top 8 bits are the command: 2109 * 2110 * 0 delete rules with given number 2111 * 1 delete rules with given set number 2112 * 2 move rules with given number to new set 2113 * 3 move rules with given set number to new set 2114 * 4 swap sets with given numbers 2115 */ 2116 static int 2117 del_entry(struct ip_fw **chain, u_int32_t arg) 2118 { 2119 struct ip_fw *prev, *rule; 2120 u_int16_t rulenum; 2121 u_int8_t cmd, new_set; 2122 2123 rulenum = arg & 0xffff; 2124 cmd = (arg >> 24) & 0xff; 2125 new_set = (arg >> 16) & 0xff; 2126 2127 if (cmd > 4) 2128 return EINVAL; 2129 if (new_set > 30) 2130 return EINVAL; 2131 if (cmd == 0 || cmd == 2) { 2132 if (rulenum == IPFW_DEFAULT_RULE) 2133 return EINVAL; 2134 } else { 2135 if (rulenum > 30) 2136 return EINVAL; 2137 } 2138 2139 switch (cmd) { 2140 case 0: /* delete rules with given number */ 2141 /* 2142 * locate first rule to delete 2143 */ 2144 for (prev = NULL, rule = *chain; 2145 rule && rule->rulenum < rulenum; 2146 prev = rule, rule = rule->next) 2147 ; 2148 if (rule->rulenum != rulenum) 2149 return EINVAL; 2150 2151 crit_enter(); /* no access to rules while removing */ 2152 /* 2153 * flush pointers outside the loop, then delete all matching 2154 * rules. prev remains the same throughout the cycle. 2155 */ 2156 flush_rule_ptrs(); 2157 while (rule && rule->rulenum == rulenum) 2158 rule = delete_rule(chain, prev, rule); 2159 crit_exit(); 2160 break; 2161 2162 case 1: /* delete all rules with given set number */ 2163 crit_enter(); 2164 flush_rule_ptrs(); 2165 for (prev = NULL, rule = *chain; rule ; ) 2166 if (rule->set == rulenum) 2167 rule = delete_rule(chain, prev, rule); 2168 else { 2169 prev = rule; 2170 rule = rule->next; 2171 } 2172 crit_exit(); 2173 break; 2174 2175 case 2: /* move rules with given number to new set */ 2176 crit_enter(); 2177 for (rule = *chain; rule ; rule = rule->next) 2178 if (rule->rulenum == rulenum) 2179 rule->set = new_set; 2180 crit_exit(); 2181 break; 2182 2183 case 3: /* move rules with given set number to new set */ 2184 crit_enter(); 2185 for (rule = *chain; rule ; rule = rule->next) 2186 if (rule->set == rulenum) 2187 rule->set = new_set; 2188 crit_exit(); 2189 break; 2190 2191 case 4: /* swap two sets */ 2192 crit_enter(); 2193 for (rule = *chain; rule ; rule = rule->next) 2194 if (rule->set == rulenum) 2195 rule->set = new_set; 2196 else if (rule->set == new_set) 2197 rule->set = rulenum; 2198 crit_exit(); 2199 break; 2200 } 2201 return 0; 2202 } 2203 2204 /* 2205 * Clear counters for a specific rule. 2206 */ 2207 static void 2208 clear_counters(struct ip_fw *rule, int log_only) 2209 { 2210 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2211 2212 if (log_only == 0) { 2213 rule->bcnt = rule->pcnt = 0; 2214 rule->timestamp = 0; 2215 } 2216 if (l->o.opcode == O_LOG) 2217 l->log_left = l->max_log; 2218 } 2219 2220 /** 2221 * Reset some or all counters on firewall rules. 2222 * @arg frwl is null to clear all entries, or contains a specific 2223 * rule number. 2224 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2225 */ 2226 static int 2227 zero_entry(int rulenum, int log_only) 2228 { 2229 struct ip_fw *rule; 2230 char *msg; 2231 2232 if (rulenum == 0) { 2233 crit_enter(); 2234 norule_counter = 0; 2235 for (rule = layer3_chain; rule; rule = rule->next) 2236 clear_counters(rule, log_only); 2237 crit_exit(); 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 crit_enter(); 2249 while (rule && rule->rulenum == rulenum) { 2250 clear_counters(rule, log_only); 2251 rule = rule->next; 2252 } 2253 crit_exit(); 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 kprintf("ipfw: rule too short\n"); 2280 return (EINVAL); 2281 } 2282 /* first, check for valid size */ 2283 l = RULESIZE(rule); 2284 if (l != size) { 2285 kprintf("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 kprintf("ipfw: opcode %d size truncated\n", 2297 cmd->opcode); 2298 return EINVAL; 2299 } 2300 DEB(kprintf("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 kprintf("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 kprintf("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 kprintf("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 kprintf("ipfw: opcode %d, action must be" 2426 " last opcode\n", 2427 cmd->opcode); 2428 return EINVAL; 2429 } 2430 break; 2431 default: 2432 kprintf("ipfw: opcode %d, unknown opcode\n", 2433 cmd->opcode); 2434 return EINVAL; 2435 } 2436 } 2437 if (have_action == 0) { 2438 kprintf("ipfw: missing action\n"); 2439 return EINVAL; 2440 } 2441 return 0; 2442 2443 bad_size: 2444 kprintf("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, 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 defined(__FreeBSD__) && __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 crit_enter(); 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 = kmalloc(size, M_TEMP, M_WAITOK); 2499 2500 bp = buf; 2501 for (rule = layer3_chain; rule ; rule = rule->next) { 2502 int i = RULESIZE(rule); 2503 bcopy(rule, bp, i); 2504 /* 2505 * abuse 'next_rule' to store the set_disable word 2506 */ 2507 bcopy(&set_disable, &(((struct ip_fw *)bp)->next_rule), 2508 sizeof(set_disable)); 2509 bp = (struct ip_fw *)((char *)bp + i); 2510 } 2511 if (ipfw_dyn_v) { 2512 int i; 2513 ipfw_dyn_rule *p, *dst, *last = NULL; 2514 2515 dst = (ipfw_dyn_rule *)bp; 2516 for (i = 0 ; i < curr_dyn_buckets ; i++ ) 2517 for ( p = ipfw_dyn_v[i] ; p != NULL ; 2518 p = p->next, dst++ ) { 2519 bcopy(p, dst, sizeof *p); 2520 bcopy(&(p->rule->rulenum), &(dst->rule), 2521 sizeof(p->rule->rulenum)); 2522 /* 2523 * store a non-null value in "next". 2524 * The userland code will interpret a 2525 * NULL here as a marker 2526 * for the last dynamic rule. 2527 */ 2528 dst->next = dst ; 2529 last = dst ; 2530 dst->expire = 2531 TIME_LEQ(dst->expire, time_second) ? 2532 0 : dst->expire - time_second ; 2533 } 2534 if (last != NULL) /* mark last dynamic rule */ 2535 last->next = NULL; 2536 } 2537 crit_exit(); 2538 2539 error = sooptcopyout(sopt, buf, size); 2540 kfree(buf, M_TEMP); 2541 break; 2542 2543 case IP_FW_FLUSH: 2544 /* 2545 * Normally we cannot release the lock on each iteration. 2546 * We could do it here only because we start from the head all 2547 * the times so there is no risk of missing some entries. 2548 * On the other hand, the risk is that we end up with 2549 * a very inconsistent ruleset, so better keep the lock 2550 * around the whole cycle. 2551 * 2552 * XXX this code can be improved by resetting the head of 2553 * the list to point to the default rule, and then freeing 2554 * the old list without the need for a lock. 2555 */ 2556 2557 crit_enter(); 2558 free_chain(&layer3_chain, 0 /* keep default rule */); 2559 crit_exit(); 2560 break; 2561 2562 case IP_FW_ADD: 2563 rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ 2564 error = sooptcopyin(sopt, rule, sizeof(rule_buf), 2565 sizeof(struct ip_fw) ); 2566 size = sopt->sopt_valsize; 2567 if (error || (error = check_ipfw_struct(rule, size))) 2568 break; 2569 2570 error = add_rule(&layer3_chain, rule); 2571 size = RULESIZE(rule); 2572 if (!error && sopt->sopt_dir == SOPT_GET) 2573 error = sooptcopyout(sopt, rule, size); 2574 break; 2575 2576 case IP_FW_DEL: 2577 /* 2578 * IP_FW_DEL is used for deleting single rules or sets, 2579 * and (ab)used to atomically manipulate sets. Argument size 2580 * is used to distinguish between the two: 2581 * sizeof(u_int32_t) 2582 * delete single rule or set of rules, 2583 * or reassign rules (or sets) to a different set. 2584 * 2*sizeof(u_int32_t) 2585 * atomic disable/enable sets. 2586 * first u_int32_t contains sets to be disabled, 2587 * second u_int32_t contains sets to be enabled. 2588 */ 2589 error = sooptcopyin(sopt, rule_buf, 2590 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2591 if (error) 2592 break; 2593 size = sopt->sopt_valsize; 2594 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2595 error = del_entry(&layer3_chain, rule_buf[0]); 2596 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2597 set_disable = 2598 (set_disable | rule_buf[0]) & ~rule_buf[1] & 2599 ~(1<<31); /* set 31 always enabled */ 2600 else 2601 error = EINVAL; 2602 break; 2603 2604 case IP_FW_ZERO: 2605 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2606 rulenum=0; 2607 2608 if (sopt->sopt_val != 0) { 2609 error = sooptcopyin(sopt, &rulenum, 2610 sizeof(int), sizeof(int)); 2611 if (error) 2612 break; 2613 } 2614 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); 2615 break; 2616 2617 default: 2618 kprintf("ipfw_ctl invalid option %d\n", sopt->sopt_name); 2619 error = EINVAL; 2620 } 2621 2622 return (error); 2623 } 2624 2625 /** 2626 * dummynet needs a reference to the default rule, because rules can be 2627 * deleted while packets hold a reference to them. When this happens, 2628 * dummynet changes the reference to the default rule (it could well be a 2629 * NULL pointer, but this way we do not need to check for the special 2630 * case, plus here he have info on the default behaviour). 2631 */ 2632 struct ip_fw *ip_fw_default_rule; 2633 2634 /* 2635 * This procedure is only used to handle keepalives. It is invoked 2636 * every dyn_keepalive_period 2637 */ 2638 static void 2639 ipfw_tick(void * __unused unused) 2640 { 2641 int i; 2642 ipfw_dyn_rule *q; 2643 2644 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2645 goto done; 2646 2647 crit_enter(); 2648 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2649 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2650 if (q->dyn_type == O_LIMIT_PARENT) 2651 continue; 2652 if (q->id.proto != IPPROTO_TCP) 2653 continue; 2654 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2655 continue; 2656 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2657 q->expire)) 2658 continue; /* too early */ 2659 if (TIME_LEQ(q->expire, time_second)) 2660 continue; /* too late, rule expired */ 2661 2662 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2663 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2664 } 2665 } 2666 crit_exit(); 2667 done: 2668 callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz, 2669 ipfw_tick, NULL); 2670 } 2671 2672 static void 2673 ipfw_init(void) 2674 { 2675 struct ip_fw default_rule; 2676 2677 ip_fw_chk_ptr = ipfw_chk; 2678 ip_fw_ctl_ptr = ipfw_ctl; 2679 layer3_chain = NULL; 2680 2681 bzero(&default_rule, sizeof default_rule); 2682 2683 default_rule.act_ofs = 0; 2684 default_rule.rulenum = IPFW_DEFAULT_RULE; 2685 default_rule.cmd_len = 1; 2686 default_rule.set = 31; 2687 2688 default_rule.cmd[0].len = 1; 2689 default_rule.cmd[0].opcode = 2690 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2691 1 ? O_ACCEPT : 2692 #endif 2693 O_DENY; 2694 2695 add_rule(&layer3_chain, &default_rule); 2696 2697 ip_fw_default_rule = layer3_chain; 2698 kprintf("ipfw2 initialized, divert %s, " 2699 "rule-based forwarding enabled, default to %s, logging ", 2700 #ifdef IPDIVERT 2701 "enabled", 2702 #else 2703 "disabled", 2704 #endif 2705 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2706 2707 #ifdef IPFIREWALL_VERBOSE 2708 fw_verbose = 1; 2709 #endif 2710 #ifdef IPFIREWALL_VERBOSE_LIMIT 2711 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2712 #endif 2713 if (fw_verbose == 0) 2714 kprintf("disabled\n"); 2715 else if (verbose_limit == 0) 2716 kprintf("unlimited\n"); 2717 else 2718 kprintf("limited to %d packets/entry by default\n", 2719 verbose_limit); 2720 callout_init(&ipfw_timeout_h); 2721 callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL); 2722 } 2723 2724 static int 2725 ipfw_modevent(module_t mod, int type, void *unused) 2726 { 2727 int err = 0; 2728 2729 switch (type) { 2730 case MOD_LOAD: 2731 crit_enter(); 2732 if (IPFW_LOADED) { 2733 crit_exit(); 2734 kprintf("IP firewall already loaded\n"); 2735 err = EEXIST; 2736 } else { 2737 ipfw_init(); 2738 crit_exit(); 2739 } 2740 break; 2741 2742 case MOD_UNLOAD: 2743 #if !defined(KLD_MODULE) 2744 kprintf("ipfw statically compiled, cannot unload\n"); 2745 err = EBUSY; 2746 #else 2747 crit_enter(); 2748 callout_stop(&ipfw_timeout_h); 2749 ip_fw_chk_ptr = NULL; 2750 ip_fw_ctl_ptr = NULL; 2751 free_chain(&layer3_chain, 1 /* kill default rule */); 2752 crit_exit(); 2753 kprintf("IP firewall unloaded\n"); 2754 #endif 2755 break; 2756 default: 2757 break; 2758 } 2759 return err; 2760 } 2761 2762 static moduledata_t ipfwmod = { 2763 "ipfw", 2764 ipfw_modevent, 2765 0 2766 }; 2767 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_END, SI_ORDER_ANY); 2768 MODULE_VERSION(ipfw, 1); 2769