Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/ip_fw2.c
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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: releng/5.1/sys/netinet/ip_fw2.c 115796 2003-06-04 02:19:36Z ticso $ 26 */ 27 28 #define DEB(x) 29 #define DDB(x) x 30 31 /* 32 * Implement IP packet firewall (new version) 33 */ 34 35 #if !defined(KLD_MODULE) 36 #include "opt_ipfw.h" 37 #include "opt_ipdn.h" 38 #include "opt_ipdivert.h" 39 #include "opt_inet.h" 40 #ifndef INET 41 #error IPFIREWALL requires INET. 42 #endif /* INET */ 43 #endif 44 45 #define IPFW2 1 46 #if IPFW2 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/malloc.h> 50 #include <sys/mbuf.h> 51 #include <sys/kernel.h> 52 #include <sys/proc.h> 53 #include <sys/socket.h> 54 #include <sys/socketvar.h> 55 #include <sys/sysctl.h> 56 #include <sys/syslog.h> 57 #include <sys/ucred.h> 58 #include <net/if.h> 59 #include <net/route.h> 60 #include <netinet/in.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/in_var.h> 63 #include <netinet/in_pcb.h> 64 #include <netinet/ip.h> 65 #include <netinet/ip_var.h> 66 #include <netinet/ip_icmp.h> 67 #include <netinet/ip_fw.h> 68 #include <netinet/ip_dummynet.h> 69 #include <netinet/tcp.h> 70 #include <netinet/tcp_timer.h> 71 #include <netinet/tcp_var.h> 72 #include <netinet/tcpip.h> 73 #include <netinet/udp.h> 74 #include <netinet/udp_var.h> 75 76 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */ 77 78 #include <machine/in_cksum.h> /* XXX for in_cksum */ 79 80 /* 81 * XXX This one should go in sys/mbuf.h. It is used to avoid that 82 * a firewall-generated packet loops forever through the firewall. 83 */ 84 #ifndef M_SKIP_FIREWALL 85 #define M_SKIP_FIREWALL 0x4000 86 #endif 87 88 /* 89 * set_disable contains one bit per set value (0..31). 90 * If the bit is set, all rules with the corresponding set 91 * are disabled. Set 31 is reserved for the default rule 92 * and CANNOT be disabled. 93 */ 94 static u_int32_t set_disable; 95 96 static int fw_verbose; 97 static int verbose_limit; 98 99 static struct callout_handle ipfw_timeout_h; 100 #define IPFW_DEFAULT_RULE 65535 101 102 /* 103 * list of rules for layer 3 104 */ 105 static struct ip_fw *layer3_chain; 106 107 MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 108 109 static int fw_debug = 1; 110 static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 111 112 #ifdef SYSCTL_NODE 113 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 114 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, 115 CTLFLAG_RW | CTLFLAG_SECURE3, 116 &fw_enable, 0, "Enable ipfw"); 117 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 118 &autoinc_step, 0, "Rule number autincrement step"); 119 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, one_pass, 120 CTLFLAG_RW | CTLFLAG_SECURE3, 121 &fw_one_pass, 0, 122 "Only do a single pass through ipfw when using dummynet(4)"); 123 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 124 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 125 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, 126 CTLFLAG_RW | CTLFLAG_SECURE3, 127 &fw_verbose, 0, "Log matches to ipfw rules"); 128 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 129 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 130 131 /* 132 * Description of dynamic rules. 133 * 134 * Dynamic rules are stored in lists accessed through a hash table 135 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 136 * be modified through the sysctl variable dyn_buckets which is 137 * updated when the table becomes empty. 138 * 139 * XXX currently there is only one list, ipfw_dyn. 140 * 141 * When a packet is received, its address fields are first masked 142 * with the mask defined for the rule, then hashed, then matched 143 * against the entries in the corresponding list. 144 * Dynamic rules can be used for different purposes: 145 * + stateful rules; 146 * + enforcing limits on the number of sessions; 147 * + in-kernel NAT (not implemented yet) 148 * 149 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 150 * measured in seconds and depending on the flags. 151 * 152 * The total number of dynamic rules is stored in dyn_count. 153 * The max number of dynamic rules is dyn_max. When we reach 154 * the maximum number of rules we do not create anymore. This is 155 * done to avoid consuming too much memory, but also too much 156 * time when searching on each packet (ideally, we should try instead 157 * to put a limit on the length of the list on each bucket...). 158 * 159 * Each dynamic rule holds a pointer to the parent ipfw rule so 160 * we know what action to perform. Dynamic rules are removed when 161 * the parent rule is deleted. XXX we should make them survive. 162 * 163 * There are some limitations with dynamic rules -- we do not 164 * obey the 'randomized match', and we do not do multiple 165 * passes through the firewall. XXX check the latter!!! 166 */ 167 static ipfw_dyn_rule **ipfw_dyn_v = NULL; 168 static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 169 static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 170 171 /* 172 * Timeouts for various events in handing dynamic rules. 173 */ 174 static u_int32_t dyn_ack_lifetime = 300; 175 static u_int32_t dyn_syn_lifetime = 20; 176 static u_int32_t dyn_fin_lifetime = 1; 177 static u_int32_t dyn_rst_lifetime = 1; 178 static u_int32_t dyn_udp_lifetime = 10; 179 static u_int32_t dyn_short_lifetime = 5; 180 181 /* 182 * Keepalives are sent if dyn_keepalive is set. They are sent every 183 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 184 * seconds of lifetime of a rule. 185 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 186 * than dyn_keepalive_period. 187 */ 188 189 static u_int32_t dyn_keepalive_interval = 20; 190 static u_int32_t dyn_keepalive_period = 5; 191 static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 192 193 static u_int32_t static_count; /* # of static rules */ 194 static u_int32_t static_len; /* size in bytes of static rules */ 195 static u_int32_t dyn_count; /* # of dynamic rules */ 196 static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 197 198 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 199 &dyn_buckets, 0, "Number of dyn. buckets"); 200 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 201 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 202 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 203 &dyn_count, 0, "Number of dyn. rules"); 204 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 205 &dyn_max, 0, "Max number of dyn. rules"); 206 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 207 &static_count, 0, "Number of static rules"); 208 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 209 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 210 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 211 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 212 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 213 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 214 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 215 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 216 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 217 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 218 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 219 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 220 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 221 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 222 223 #endif /* SYSCTL_NODE */ 224 225 226 static ip_fw_chk_t ipfw_chk; 227 228 ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 229 230 /* 231 * This macro maps an ip pointer into a layer3 header pointer of type T 232 */ 233 #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 234 235 static __inline int 236 icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 237 { 238 int type = L3HDR(struct icmp,ip)->icmp_type; 239 240 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 241 } 242 243 #define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 244 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 245 246 static int 247 is_icmp_query(struct ip *ip) 248 { 249 int type = L3HDR(struct icmp, ip)->icmp_type; 250 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 251 } 252 #undef TT 253 254 /* 255 * The following checks use two arrays of 8 or 16 bits to store the 256 * bits that we want set or clear, respectively. They are in the 257 * low and high half of cmd->arg1 or cmd->d[0]. 258 * 259 * We scan options and store the bits we find set. We succeed if 260 * 261 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 262 * 263 * The code is sometimes optimized not to store additional variables. 264 */ 265 266 static int 267 flags_match(ipfw_insn *cmd, u_int8_t bits) 268 { 269 u_char want_clear; 270 bits = ~bits; 271 272 if ( ((cmd->arg1 & 0xff) & bits) != 0) 273 return 0; /* some bits we want set were clear */ 274 want_clear = (cmd->arg1 >> 8) & 0xff; 275 if ( (want_clear & bits) != want_clear) 276 return 0; /* some bits we want clear were set */ 277 return 1; 278 } 279 280 static int 281 ipopts_match(struct ip *ip, ipfw_insn *cmd) 282 { 283 int optlen, bits = 0; 284 u_char *cp = (u_char *)(ip + 1); 285 int x = (ip->ip_hl << 2) - sizeof (struct ip); 286 287 for (; x > 0; x -= optlen, cp += optlen) { 288 int opt = cp[IPOPT_OPTVAL]; 289 290 if (opt == IPOPT_EOL) 291 break; 292 if (opt == IPOPT_NOP) 293 optlen = 1; 294 else { 295 optlen = cp[IPOPT_OLEN]; 296 if (optlen <= 0 || optlen > x) 297 return 0; /* invalid or truncated */ 298 } 299 switch (opt) { 300 301 default: 302 break; 303 304 case IPOPT_LSRR: 305 bits |= IP_FW_IPOPT_LSRR; 306 break; 307 308 case IPOPT_SSRR: 309 bits |= IP_FW_IPOPT_SSRR; 310 break; 311 312 case IPOPT_RR: 313 bits |= IP_FW_IPOPT_RR; 314 break; 315 316 case IPOPT_TS: 317 bits |= IP_FW_IPOPT_TS; 318 break; 319 } 320 } 321 return (flags_match(cmd, bits)); 322 } 323 324 static int 325 tcpopts_match(struct ip *ip, ipfw_insn *cmd) 326 { 327 int optlen, bits = 0; 328 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 329 u_char *cp = (u_char *)(tcp + 1); 330 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 331 332 for (; x > 0; x -= optlen, cp += optlen) { 333 int opt = cp[0]; 334 if (opt == TCPOPT_EOL) 335 break; 336 if (opt == TCPOPT_NOP) 337 optlen = 1; 338 else { 339 optlen = cp[1]; 340 if (optlen <= 0) 341 break; 342 } 343 344 switch (opt) { 345 346 default: 347 break; 348 349 case TCPOPT_MAXSEG: 350 bits |= IP_FW_TCPOPT_MSS; 351 break; 352 353 case TCPOPT_WINDOW: 354 bits |= IP_FW_TCPOPT_WINDOW; 355 break; 356 357 case TCPOPT_SACK_PERMITTED: 358 case TCPOPT_SACK: 359 bits |= IP_FW_TCPOPT_SACK; 360 break; 361 362 case TCPOPT_TIMESTAMP: 363 bits |= IP_FW_TCPOPT_TS; 364 break; 365 366 case TCPOPT_CC: 367 case TCPOPT_CCNEW: 368 case TCPOPT_CCECHO: 369 bits |= IP_FW_TCPOPT_CC; 370 break; 371 } 372 } 373 return (flags_match(cmd, bits)); 374 } 375 376 static int 377 iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 378 { 379 if (ifp == NULL) /* no iface with this packet, match fails */ 380 return 0; 381 /* Check by name or by IP address */ 382 if (cmd->name[0] != '\0') { /* match by name */ 383 /* Check unit number (-1 is wildcard) */ 384 if (cmd->p.unit != -1 && cmd->p.unit != ifp->if_unit) 385 return(0); 386 /* Check name */ 387 if (!strncmp(ifp->if_name, cmd->name, IFNAMSIZ)) 388 return(1); 389 } else { 390 struct ifaddr *ia; 391 392 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 393 if (ia->ifa_addr == NULL) 394 continue; 395 if (ia->ifa_addr->sa_family != AF_INET) 396 continue; 397 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 398 (ia->ifa_addr))->sin_addr.s_addr) 399 return(1); /* match */ 400 } 401 } 402 return(0); /* no match, fail ... */ 403 } 404 405 /* 406 * The 'verrevpath' option checks that the interface that an IP packet 407 * arrives on is the same interface that traffic destined for the 408 * packet's source address would be routed out of. This is a measure 409 * to block forged packets. This is also commonly known as "anti-spoofing" 410 * or Unicast Reverse Path Forwarding (Unicast RFP) in Cisco-ese. The 411 * name of the knob is purposely reminisent of the Cisco IOS command, 412 * 413 * ip verify unicast reverse-path 414 * 415 * which implements the same functionality. But note that syntax is 416 * misleading. The check may be performed on all IP packets whether unicast, 417 * multicast, or broadcast. 418 */ 419 static int 420 verify_rev_path(struct in_addr src, struct ifnet *ifp) 421 { 422 static struct route ro; 423 struct sockaddr_in *dst; 424 425 dst = (struct sockaddr_in *)&(ro.ro_dst); 426 427 /* Check if we've cached the route from the previous call. */ 428 if (src.s_addr != dst->sin_addr.s_addr) { 429 ro.ro_rt = NULL; 430 431 bzero(dst, sizeof(*dst)); 432 dst->sin_family = AF_INET; 433 dst->sin_len = sizeof(*dst); 434 dst->sin_addr = src; 435 436 rtalloc_ign(&ro, RTF_CLONING|RTF_PRCLONING); 437 } 438 439 if ((ro.ro_rt == NULL) || (ifp == NULL) || 440 (ro.ro_rt->rt_ifp->if_index != ifp->if_index)) 441 return 0; 442 443 return 1; 444 } 445 446 447 static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 448 449 #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 450 #define SNP(buf) buf, sizeof(buf) 451 452 /* 453 * We enter here when we have a rule with O_LOG. 454 * XXX this function alone takes about 2Kbytes of code! 455 */ 456 static void 457 ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 458 struct mbuf *m, struct ifnet *oif) 459 { 460 char *action; 461 int limit_reached = 0; 462 char action2[40], proto[48], fragment[28]; 463 464 fragment[0] = '\0'; 465 proto[0] = '\0'; 466 467 if (f == NULL) { /* bogus pkt */ 468 if (verbose_limit != 0 && norule_counter >= verbose_limit) 469 return; 470 norule_counter++; 471 if (norule_counter == verbose_limit) 472 limit_reached = verbose_limit; 473 action = "Refuse"; 474 } else { /* O_LOG is the first action, find the real one */ 475 ipfw_insn *cmd = ACTION_PTR(f); 476 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 477 478 if (l->max_log != 0 && l->log_left == 0) 479 return; 480 l->log_left--; 481 if (l->log_left == 0) 482 limit_reached = l->max_log; 483 cmd += F_LEN(cmd); /* point to first action */ 484 if (cmd->opcode == O_PROB) 485 cmd += F_LEN(cmd); 486 487 action = action2; 488 switch (cmd->opcode) { 489 case O_DENY: 490 action = "Deny"; 491 break; 492 493 case O_REJECT: 494 if (cmd->arg1==ICMP_REJECT_RST) 495 action = "Reset"; 496 else if (cmd->arg1==ICMP_UNREACH_HOST) 497 action = "Reject"; 498 else 499 snprintf(SNPARGS(action2, 0), "Unreach %d", 500 cmd->arg1); 501 break; 502 503 case O_ACCEPT: 504 action = "Accept"; 505 break; 506 case O_COUNT: 507 action = "Count"; 508 break; 509 case O_DIVERT: 510 snprintf(SNPARGS(action2, 0), "Divert %d", 511 cmd->arg1); 512 break; 513 case O_TEE: 514 snprintf(SNPARGS(action2, 0), "Tee %d", 515 cmd->arg1); 516 break; 517 case O_SKIPTO: 518 snprintf(SNPARGS(action2, 0), "SkipTo %d", 519 cmd->arg1); 520 break; 521 case O_PIPE: 522 snprintf(SNPARGS(action2, 0), "Pipe %d", 523 cmd->arg1); 524 break; 525 case O_QUEUE: 526 snprintf(SNPARGS(action2, 0), "Queue %d", 527 cmd->arg1); 528 break; 529 case O_FORWARD_IP: { 530 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 531 int len; 532 533 len = snprintf(SNPARGS(action2, 0), "Forward to %s", 534 inet_ntoa(sa->sa.sin_addr)); 535 if (sa->sa.sin_port) 536 snprintf(SNPARGS(action2, len), ":%d", 537 sa->sa.sin_port); 538 } 539 break; 540 default: 541 action = "UNKNOWN"; 542 break; 543 } 544 } 545 546 if (hlen == 0) { /* non-ip */ 547 snprintf(SNPARGS(proto, 0), "MAC"); 548 } else { 549 struct ip *ip = mtod(m, struct ip *); 550 /* these three are all aliases to the same thing */ 551 struct icmp *const icmp = L3HDR(struct icmp, ip); 552 struct tcphdr *const tcp = (struct tcphdr *)icmp; 553 struct udphdr *const udp = (struct udphdr *)icmp; 554 555 int ip_off, offset, ip_len; 556 557 int len; 558 559 if (eh != NULL) { /* layer 2 packets are as on the wire */ 560 ip_off = ntohs(ip->ip_off); 561 ip_len = ntohs(ip->ip_len); 562 } else { 563 ip_off = ip->ip_off; 564 ip_len = ip->ip_len; 565 } 566 offset = ip_off & IP_OFFMASK; 567 switch (ip->ip_p) { 568 case IPPROTO_TCP: 569 len = snprintf(SNPARGS(proto, 0), "TCP %s", 570 inet_ntoa(ip->ip_src)); 571 if (offset == 0) 572 snprintf(SNPARGS(proto, len), ":%d %s:%d", 573 ntohs(tcp->th_sport), 574 inet_ntoa(ip->ip_dst), 575 ntohs(tcp->th_dport)); 576 else 577 snprintf(SNPARGS(proto, len), " %s", 578 inet_ntoa(ip->ip_dst)); 579 break; 580 581 case IPPROTO_UDP: 582 len = snprintf(SNPARGS(proto, 0), "UDP %s", 583 inet_ntoa(ip->ip_src)); 584 if (offset == 0) 585 snprintf(SNPARGS(proto, len), ":%d %s:%d", 586 ntohs(udp->uh_sport), 587 inet_ntoa(ip->ip_dst), 588 ntohs(udp->uh_dport)); 589 else 590 snprintf(SNPARGS(proto, len), " %s", 591 inet_ntoa(ip->ip_dst)); 592 break; 593 594 case IPPROTO_ICMP: 595 if (offset == 0) 596 len = snprintf(SNPARGS(proto, 0), 597 "ICMP:%u.%u ", 598 icmp->icmp_type, icmp->icmp_code); 599 else 600 len = snprintf(SNPARGS(proto, 0), "ICMP "); 601 len += snprintf(SNPARGS(proto, len), "%s", 602 inet_ntoa(ip->ip_src)); 603 snprintf(SNPARGS(proto, len), " %s", 604 inet_ntoa(ip->ip_dst)); 605 break; 606 607 default: 608 len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 609 inet_ntoa(ip->ip_src)); 610 snprintf(SNPARGS(proto, len), " %s", 611 inet_ntoa(ip->ip_dst)); 612 break; 613 } 614 615 if (ip_off & (IP_MF | IP_OFFMASK)) 616 snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 617 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 618 offset << 3, 619 (ip_off & IP_MF) ? "+" : ""); 620 } 621 if (oif || m->m_pkthdr.rcvif) 622 log(LOG_SECURITY | LOG_INFO, 623 "ipfw: %d %s %s %s via %s%d%s\n", 624 f ? f->rulenum : -1, 625 action, proto, oif ? "out" : "in", 626 oif ? oif->if_name : m->m_pkthdr.rcvif->if_name, 627 oif ? oif->if_unit : m->m_pkthdr.rcvif->if_unit, 628 fragment); 629 else 630 log(LOG_SECURITY | LOG_INFO, 631 "ipfw: %d %s %s [no if info]%s\n", 632 f ? f->rulenum : -1, 633 action, proto, fragment); 634 if (limit_reached) 635 log(LOG_SECURITY | LOG_NOTICE, 636 "ipfw: limit %d reached on entry %d\n", 637 limit_reached, f ? f->rulenum : -1); 638 } 639 640 /* 641 * IMPORTANT: the hash function for dynamic rules must be commutative 642 * in source and destination (ip,port), because rules are bidirectional 643 * and we want to find both in the same bucket. 644 */ 645 static __inline int 646 hash_packet(struct ipfw_flow_id *id) 647 { 648 u_int32_t i; 649 650 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 651 i &= (curr_dyn_buckets - 1); 652 return i; 653 } 654 655 /** 656 * unlink a dynamic rule from a chain. prev is a pointer to 657 * the previous one, q is a pointer to the rule to delete, 658 * head is a pointer to the head of the queue. 659 * Modifies q and potentially also head. 660 */ 661 #define UNLINK_DYN_RULE(prev, head, q) { \ 662 ipfw_dyn_rule *old_q = q; \ 663 \ 664 /* remove a refcount to the parent */ \ 665 if (q->dyn_type == O_LIMIT) \ 666 q->parent->count--; \ 667 DEB(printf("ipfw: unlink entry 0x%08x %d -> 0x%08x %d, %d left\n",\ 668 (q->id.src_ip), (q->id.src_port), \ 669 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 670 if (prev != NULL) \ 671 prev->next = q = q->next; \ 672 else \ 673 head = q = q->next; \ 674 dyn_count--; \ 675 free(old_q, M_IPFW); } 676 677 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 678 679 /** 680 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 681 * 682 * If keep_me == NULL, rules are deleted even if not expired, 683 * otherwise only expired rules are removed. 684 * 685 * The value of the second parameter is also used to point to identify 686 * a rule we absolutely do not want to remove (e.g. because we are 687 * holding a reference to it -- this is the case with O_LIMIT_PARENT 688 * rules). The pointer is only used for comparison, so any non-null 689 * value will do. 690 */ 691 static void 692 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 693 { 694 static u_int32_t last_remove = 0; 695 696 #define FORCE (keep_me == NULL) 697 698 ipfw_dyn_rule *prev, *q; 699 int i, pass = 0, max_pass = 0; 700 701 if (ipfw_dyn_v == NULL || dyn_count == 0) 702 return; 703 /* do not expire more than once per second, it is useless */ 704 if (!FORCE && last_remove == time_second) 705 return; 706 last_remove = time_second; 707 708 /* 709 * because O_LIMIT refer to parent rules, during the first pass only 710 * remove child and mark any pending LIMIT_PARENT, and remove 711 * them in a second pass. 712 */ 713 next_pass: 714 for (i = 0 ; i < curr_dyn_buckets ; i++) { 715 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 716 /* 717 * Logic can become complex here, so we split tests. 718 */ 719 if (q == keep_me) 720 goto next; 721 if (rule != NULL && rule != q->rule) 722 goto next; /* not the one we are looking for */ 723 if (q->dyn_type == O_LIMIT_PARENT) { 724 /* 725 * handle parent in the second pass, 726 * record we need one. 727 */ 728 max_pass = 1; 729 if (pass == 0) 730 goto next; 731 if (FORCE && q->count != 0 ) { 732 /* XXX should not happen! */ 733 printf("ipfw: OUCH! cannot remove rule," 734 " count %d\n", q->count); 735 } 736 } else { 737 if (!FORCE && 738 !TIME_LEQ( q->expire, time_second )) 739 goto next; 740 } 741 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 742 continue; 743 next: 744 prev=q; 745 q=q->next; 746 } 747 } 748 if (pass++ < max_pass) 749 goto next_pass; 750 } 751 752 753 /** 754 * lookup a dynamic rule. 755 */ 756 static ipfw_dyn_rule * 757 lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 758 struct tcphdr *tcp) 759 { 760 /* 761 * stateful ipfw extensions. 762 * Lookup into dynamic session queue 763 */ 764 #define MATCH_REVERSE 0 765 #define MATCH_FORWARD 1 766 #define MATCH_NONE 2 767 #define MATCH_UNKNOWN 3 768 int i, dir = MATCH_NONE; 769 ipfw_dyn_rule *prev, *q=NULL; 770 771 if (ipfw_dyn_v == NULL) 772 goto done; /* not found */ 773 i = hash_packet( pkt ); 774 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 775 if (q->dyn_type == O_LIMIT_PARENT) 776 goto next; 777 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 778 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 779 continue; 780 } 781 if ( pkt->proto == q->id.proto) { 782 if (pkt->src_ip == q->id.src_ip && 783 pkt->dst_ip == q->id.dst_ip && 784 pkt->src_port == q->id.src_port && 785 pkt->dst_port == q->id.dst_port ) { 786 dir = MATCH_FORWARD; 787 break; 788 } 789 if (pkt->src_ip == q->id.dst_ip && 790 pkt->dst_ip == q->id.src_ip && 791 pkt->src_port == q->id.dst_port && 792 pkt->dst_port == q->id.src_port ) { 793 dir = MATCH_REVERSE; 794 break; 795 } 796 } 797 next: 798 prev = q; 799 q = q->next; 800 } 801 if (q == NULL) 802 goto done; /* q = NULL, not found */ 803 804 if ( prev != NULL) { /* found and not in front */ 805 prev->next = q->next; 806 q->next = ipfw_dyn_v[i]; 807 ipfw_dyn_v[i] = q; 808 } 809 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 810 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 811 812 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 813 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 814 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 815 switch (q->state) { 816 case TH_SYN: /* opening */ 817 q->expire = time_second + dyn_syn_lifetime; 818 break; 819 820 case BOTH_SYN: /* move to established */ 821 case BOTH_SYN | TH_FIN : /* one side tries to close */ 822 case BOTH_SYN | (TH_FIN << 8) : 823 if (tcp) { 824 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 825 u_int32_t ack = ntohl(tcp->th_ack); 826 if (dir == MATCH_FORWARD) { 827 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 828 q->ack_fwd = ack; 829 else { /* ignore out-of-sequence */ 830 break; 831 } 832 } else { 833 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 834 q->ack_rev = ack; 835 else { /* ignore out-of-sequence */ 836 break; 837 } 838 } 839 } 840 q->expire = time_second + dyn_ack_lifetime; 841 break; 842 843 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 844 if (dyn_fin_lifetime >= dyn_keepalive_period) 845 dyn_fin_lifetime = dyn_keepalive_period - 1; 846 q->expire = time_second + dyn_fin_lifetime; 847 break; 848 849 default: 850 #if 0 851 /* 852 * reset or some invalid combination, but can also 853 * occur if we use keep-state the wrong way. 854 */ 855 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 856 printf("invalid state: 0x%x\n", q->state); 857 #endif 858 if (dyn_rst_lifetime >= dyn_keepalive_period) 859 dyn_rst_lifetime = dyn_keepalive_period - 1; 860 q->expire = time_second + dyn_rst_lifetime; 861 break; 862 } 863 } else if (pkt->proto == IPPROTO_UDP) { 864 q->expire = time_second + dyn_udp_lifetime; 865 } else { 866 /* other protocols */ 867 q->expire = time_second + dyn_short_lifetime; 868 } 869 done: 870 if (match_direction) 871 *match_direction = dir; 872 return q; 873 } 874 875 static void 876 realloc_dynamic_table(void) 877 { 878 /* 879 * Try reallocation, make sure we have a power of 2 and do 880 * not allow more than 64k entries. In case of overflow, 881 * default to 1024. 882 */ 883 884 if (dyn_buckets > 65536) 885 dyn_buckets = 1024; 886 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 887 dyn_buckets = curr_dyn_buckets; /* reset */ 888 return; 889 } 890 curr_dyn_buckets = dyn_buckets; 891 if (ipfw_dyn_v != NULL) 892 free(ipfw_dyn_v, M_IPFW); 893 for (;;) { 894 ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 895 M_IPFW, M_NOWAIT | M_ZERO); 896 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 897 break; 898 curr_dyn_buckets /= 2; 899 } 900 } 901 902 /** 903 * Install state of type 'type' for a dynamic session. 904 * The hash table contains two type of rules: 905 * - regular rules (O_KEEP_STATE) 906 * - rules for sessions with limited number of sess per user 907 * (O_LIMIT). When they are created, the parent is 908 * increased by 1, and decreased on delete. In this case, 909 * the third parameter is the parent rule and not the chain. 910 * - "parent" rules for the above (O_LIMIT_PARENT). 911 */ 912 static ipfw_dyn_rule * 913 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 914 { 915 ipfw_dyn_rule *r; 916 int i; 917 918 if (ipfw_dyn_v == NULL || 919 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 920 realloc_dynamic_table(); 921 if (ipfw_dyn_v == NULL) 922 return NULL; /* failed ! */ 923 } 924 i = hash_packet(id); 925 926 r = malloc(sizeof *r, M_IPFW, M_NOWAIT | M_ZERO); 927 if (r == NULL) { 928 printf ("ipfw: sorry cannot allocate state\n"); 929 return NULL; 930 } 931 932 /* increase refcount on parent, and set pointer */ 933 if (dyn_type == O_LIMIT) { 934 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 935 if ( parent->dyn_type != O_LIMIT_PARENT) 936 panic("invalid parent"); 937 parent->count++; 938 r->parent = parent; 939 rule = parent->rule; 940 } 941 942 r->id = *id; 943 r->expire = time_second + dyn_syn_lifetime; 944 r->rule = rule; 945 r->dyn_type = dyn_type; 946 r->pcnt = r->bcnt = 0; 947 r->count = 0; 948 949 r->bucket = i; 950 r->next = ipfw_dyn_v[i]; 951 ipfw_dyn_v[i] = r; 952 dyn_count++; 953 DEB(printf("ipfw: add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 954 dyn_type, 955 (r->id.src_ip), (r->id.src_port), 956 (r->id.dst_ip), (r->id.dst_port), 957 dyn_count ); ) 958 return r; 959 } 960 961 /** 962 * lookup dynamic parent rule using pkt and rule as search keys. 963 * If the lookup fails, then install one. 964 */ 965 static ipfw_dyn_rule * 966 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 967 { 968 ipfw_dyn_rule *q; 969 int i; 970 971 if (ipfw_dyn_v) { 972 i = hash_packet( pkt ); 973 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 974 if (q->dyn_type == O_LIMIT_PARENT && 975 rule== q->rule && 976 pkt->proto == q->id.proto && 977 pkt->src_ip == q->id.src_ip && 978 pkt->dst_ip == q->id.dst_ip && 979 pkt->src_port == q->id.src_port && 980 pkt->dst_port == q->id.dst_port) { 981 q->expire = time_second + dyn_short_lifetime; 982 DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);) 983 return q; 984 } 985 } 986 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 987 } 988 989 /** 990 * Install dynamic state for rule type cmd->o.opcode 991 * 992 * Returns 1 (failure) if state is not installed because of errors or because 993 * session limitations are enforced. 994 */ 995 static int 996 install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 997 struct ip_fw_args *args) 998 { 999 static int last_log; 1000 1001 ipfw_dyn_rule *q; 1002 1003 DEB(printf("ipfw: install state type %d 0x%08x %u -> 0x%08x %u\n", 1004 cmd->o.opcode, 1005 (args->f_id.src_ip), (args->f_id.src_port), 1006 (args->f_id.dst_ip), (args->f_id.dst_port) );) 1007 1008 q = lookup_dyn_rule(&args->f_id, NULL, NULL); 1009 1010 if (q != NULL) { /* should never occur */ 1011 if (last_log != time_second) { 1012 last_log = time_second; 1013 printf("ipfw: install_state: entry already present, done\n"); 1014 } 1015 return 0; 1016 } 1017 1018 if (dyn_count >= dyn_max) 1019 /* 1020 * Run out of slots, try to remove any expired rule. 1021 */ 1022 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 1023 1024 if (dyn_count >= dyn_max) { 1025 if (last_log != time_second) { 1026 last_log = time_second; 1027 printf("ipfw: install_state: Too many dynamic rules\n"); 1028 } 1029 return 1; /* cannot install, notify caller */ 1030 } 1031 1032 switch (cmd->o.opcode) { 1033 case O_KEEP_STATE: /* bidir rule */ 1034 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 1035 break; 1036 1037 case O_LIMIT: /* limit number of sessions */ 1038 { 1039 u_int16_t limit_mask = cmd->limit_mask; 1040 struct ipfw_flow_id id; 1041 ipfw_dyn_rule *parent; 1042 1043 DEB(printf("ipfw: installing dyn-limit rule %d\n", 1044 cmd->conn_limit);) 1045 1046 id.dst_ip = id.src_ip = 0; 1047 id.dst_port = id.src_port = 0; 1048 id.proto = args->f_id.proto; 1049 1050 if (limit_mask & DYN_SRC_ADDR) 1051 id.src_ip = args->f_id.src_ip; 1052 if (limit_mask & DYN_DST_ADDR) 1053 id.dst_ip = args->f_id.dst_ip; 1054 if (limit_mask & DYN_SRC_PORT) 1055 id.src_port = args->f_id.src_port; 1056 if (limit_mask & DYN_DST_PORT) 1057 id.dst_port = args->f_id.dst_port; 1058 parent = lookup_dyn_parent(&id, rule); 1059 if (parent == NULL) { 1060 printf("ipfw: add parent failed\n"); 1061 return 1; 1062 } 1063 if (parent->count >= cmd->conn_limit) { 1064 /* 1065 * See if we can remove some expired rule. 1066 */ 1067 remove_dyn_rule(rule, parent); 1068 if (parent->count >= cmd->conn_limit) { 1069 if (fw_verbose && last_log != time_second) { 1070 last_log = time_second; 1071 log(LOG_SECURITY | LOG_DEBUG, 1072 "drop session, too many entries\n"); 1073 } 1074 return 1; 1075 } 1076 } 1077 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1078 } 1079 break; 1080 default: 1081 printf("ipfw: unknown dynamic rule type %u\n", cmd->o.opcode); 1082 return 1; 1083 } 1084 lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1085 return 0; 1086 } 1087 1088 /* 1089 * Transmit a TCP packet, containing either a RST or a keepalive. 1090 * When flags & TH_RST, we are sending a RST packet, because of a 1091 * "reset" action matched the packet. 1092 * Otherwise we are sending a keepalive, and flags & TH_ 1093 */ 1094 static void 1095 send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1096 { 1097 struct mbuf *m; 1098 struct ip *ip; 1099 struct tcphdr *tcp; 1100 struct route sro; /* fake route */ 1101 1102 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1103 if (m == 0) 1104 return; 1105 m->m_pkthdr.rcvif = (struct ifnet *)0; 1106 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1107 m->m_data += max_linkhdr; 1108 1109 ip = mtod(m, struct ip *); 1110 bzero(ip, m->m_len); 1111 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1112 ip->ip_p = IPPROTO_TCP; 1113 tcp->th_off = 5; 1114 /* 1115 * Assume we are sending a RST (or a keepalive in the reverse 1116 * direction), swap src and destination addresses and ports. 1117 */ 1118 ip->ip_src.s_addr = htonl(id->dst_ip); 1119 ip->ip_dst.s_addr = htonl(id->src_ip); 1120 tcp->th_sport = htons(id->dst_port); 1121 tcp->th_dport = htons(id->src_port); 1122 if (flags & TH_RST) { /* we are sending a RST */ 1123 if (flags & TH_ACK) { 1124 tcp->th_seq = htonl(ack); 1125 tcp->th_ack = htonl(0); 1126 tcp->th_flags = TH_RST; 1127 } else { 1128 if (flags & TH_SYN) 1129 seq++; 1130 tcp->th_seq = htonl(0); 1131 tcp->th_ack = htonl(seq); 1132 tcp->th_flags = TH_RST | TH_ACK; 1133 } 1134 } else { 1135 /* 1136 * We are sending a keepalive. flags & TH_SYN determines 1137 * the direction, forward if set, reverse if clear. 1138 * NOTE: seq and ack are always assumed to be correct 1139 * as set by the caller. This may be confusing... 1140 */ 1141 if (flags & TH_SYN) { 1142 /* 1143 * we have to rewrite the correct addresses! 1144 */ 1145 ip->ip_dst.s_addr = htonl(id->dst_ip); 1146 ip->ip_src.s_addr = htonl(id->src_ip); 1147 tcp->th_dport = htons(id->dst_port); 1148 tcp->th_sport = htons(id->src_port); 1149 } 1150 tcp->th_seq = htonl(seq); 1151 tcp->th_ack = htonl(ack); 1152 tcp->th_flags = TH_ACK; 1153 } 1154 /* 1155 * set ip_len to the payload size so we can compute 1156 * the tcp checksum on the pseudoheader 1157 * XXX check this, could save a couple of words ? 1158 */ 1159 ip->ip_len = htons(sizeof(struct tcphdr)); 1160 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1161 /* 1162 * now fill fields left out earlier 1163 */ 1164 ip->ip_ttl = ip_defttl; 1165 ip->ip_len = m->m_pkthdr.len; 1166 bzero (&sro, sizeof (sro)); 1167 ip_rtaddr(ip->ip_dst, &sro); 1168 m->m_flags |= M_SKIP_FIREWALL; 1169 ip_output(m, NULL, &sro, 0, NULL, NULL); 1170 if (sro.ro_rt) 1171 RTFREE(sro.ro_rt); 1172 } 1173 1174 /* 1175 * sends a reject message, consuming the mbuf passed as an argument. 1176 */ 1177 static void 1178 send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1179 { 1180 1181 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1182 /* We need the IP header in host order for icmp_error(). */ 1183 if (args->eh != NULL) { 1184 struct ip *ip = mtod(args->m, struct ip *); 1185 ip->ip_len = ntohs(ip->ip_len); 1186 ip->ip_off = ntohs(ip->ip_off); 1187 } 1188 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1189 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1190 struct tcphdr *const tcp = 1191 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1192 if ( (tcp->th_flags & TH_RST) == 0) 1193 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1194 ntohl(tcp->th_ack), 1195 tcp->th_flags | TH_RST); 1196 m_freem(args->m); 1197 } else 1198 m_freem(args->m); 1199 args->m = NULL; 1200 } 1201 1202 /** 1203 * 1204 * Given an ip_fw *, lookup_next_rule will return a pointer 1205 * to the next rule, which can be either the jump 1206 * target (for skipto instructions) or the next one in the list (in 1207 * all other cases including a missing jump target). 1208 * The result is also written in the "next_rule" field of the rule. 1209 * Backward jumps are not allowed, so start looking from the next 1210 * rule... 1211 * 1212 * This never returns NULL -- in case we do not have an exact match, 1213 * the next rule is returned. When the ruleset is changed, 1214 * pointers are flushed so we are always correct. 1215 */ 1216 1217 static struct ip_fw * 1218 lookup_next_rule(struct ip_fw *me) 1219 { 1220 struct ip_fw *rule = NULL; 1221 ipfw_insn *cmd; 1222 1223 /* look for action, in case it is a skipto */ 1224 cmd = ACTION_PTR(me); 1225 if (cmd->opcode == O_LOG) 1226 cmd += F_LEN(cmd); 1227 if ( cmd->opcode == O_SKIPTO ) 1228 for (rule = me->next; rule ; rule = rule->next) 1229 if (rule->rulenum >= cmd->arg1) 1230 break; 1231 if (rule == NULL) /* failure or not a skipto */ 1232 rule = me->next; 1233 me->next_rule = rule; 1234 return rule; 1235 } 1236 1237 /* 1238 * The main check routine for the firewall. 1239 * 1240 * All arguments are in args so we can modify them and return them 1241 * back to the caller. 1242 * 1243 * Parameters: 1244 * 1245 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1246 * Starts with the IP header. 1247 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1248 * args->oif Outgoing interface, or NULL if packet is incoming. 1249 * The incoming interface is in the mbuf. (in) 1250 * args->divert_rule (in/out) 1251 * Skip up to the first rule past this rule number; 1252 * upon return, non-zero port number for divert or tee. 1253 * 1254 * args->rule Pointer to the last matching rule (in/out) 1255 * args->next_hop Socket we are forwarding to (out). 1256 * args->f_id Addresses grabbed from the packet (out) 1257 * 1258 * Return value: 1259 * 1260 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1261 * 0 The packet is to be accepted and routed normally OR 1262 * the packet was denied/rejected and has been dropped; 1263 * in the latter case, *m is equal to NULL upon return. 1264 * port Divert the packet to port, with these caveats: 1265 * 1266 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1267 * of diverting it (ie, 'ipfw tee'). 1268 * 1269 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1270 * 16 bits as a dummynet pipe number instead of diverting 1271 */ 1272 1273 static int 1274 ipfw_chk(struct ip_fw_args *args) 1275 { 1276 /* 1277 * Local variables hold state during the processing of a packet. 1278 * 1279 * IMPORTANT NOTE: to speed up the processing of rules, there 1280 * are some assumption on the values of the variables, which 1281 * are documented here. Should you change them, please check 1282 * the implementation of the various instructions to make sure 1283 * that they still work. 1284 * 1285 * args->eh The MAC header. It is non-null for a layer2 1286 * packet, it is NULL for a layer-3 packet. 1287 * 1288 * m | args->m Pointer to the mbuf, as received from the caller. 1289 * It may change if ipfw_chk() does an m_pullup, or if it 1290 * consumes the packet because it calls send_reject(). 1291 * XXX This has to change, so that ipfw_chk() never modifies 1292 * or consumes the buffer. 1293 * ip is simply an alias of the value of m, and it is kept 1294 * in sync with it (the packet is supposed to start with 1295 * the ip header). 1296 */ 1297 struct mbuf *m = args->m; 1298 struct ip *ip = mtod(m, struct ip *); 1299 1300 /* 1301 * oif | args->oif If NULL, ipfw_chk has been called on the 1302 * inbound path (ether_input, bdg_forward, ip_input). 1303 * If non-NULL, ipfw_chk has been called on the outbound path 1304 * (ether_output, ip_output). 1305 */ 1306 struct ifnet *oif = args->oif; 1307 1308 struct ip_fw *f = NULL; /* matching rule */ 1309 int retval = 0; 1310 1311 /* 1312 * hlen The length of the IPv4 header. 1313 * hlen >0 means we have an IPv4 packet. 1314 */ 1315 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1316 1317 /* 1318 * offset The offset of a fragment. offset != 0 means that 1319 * we have a fragment at this offset of an IPv4 packet. 1320 * offset == 0 means that (if this is an IPv4 packet) 1321 * this is the first or only fragment. 1322 */ 1323 u_short offset = 0; 1324 1325 /* 1326 * Local copies of addresses. They are only valid if we have 1327 * an IP packet. 1328 * 1329 * proto The protocol. Set to 0 for non-ip packets, 1330 * or to the protocol read from the packet otherwise. 1331 * proto != 0 means that we have an IPv4 packet. 1332 * 1333 * src_port, dst_port port numbers, in HOST format. Only 1334 * valid for TCP and UDP packets. 1335 * 1336 * src_ip, dst_ip ip addresses, in NETWORK format. 1337 * Only valid for IPv4 packets. 1338 */ 1339 u_int8_t proto; 1340 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1341 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1342 u_int16_t ip_len=0; 1343 int dyn_dir = MATCH_UNKNOWN; 1344 ipfw_dyn_rule *q = NULL; 1345 1346 if (m->m_flags & M_SKIP_FIREWALL) 1347 return 0; /* accept */ 1348 /* 1349 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1350 * MATCH_NONE when checked and not matched (q = NULL), 1351 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1352 */ 1353 1354 if (args->eh == NULL || /* layer 3 packet */ 1355 ( m->m_pkthdr.len >= sizeof(struct ip) && 1356 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1357 hlen = ip->ip_hl << 2; 1358 1359 /* 1360 * Collect parameters into local variables for faster matching. 1361 */ 1362 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1363 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1364 goto after_ip_checks; 1365 } 1366 1367 proto = args->f_id.proto = ip->ip_p; 1368 src_ip = ip->ip_src; 1369 dst_ip = ip->ip_dst; 1370 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1371 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1372 ip_len = ntohs(ip->ip_len); 1373 } else { 1374 offset = ip->ip_off & IP_OFFMASK; 1375 ip_len = ip->ip_len; 1376 } 1377 1378 #define PULLUP_TO(len) \ 1379 do { \ 1380 if ((m)->m_len < (len)) { \ 1381 args->m = m = m_pullup(m, (len)); \ 1382 if (m == 0) \ 1383 goto pullup_failed; \ 1384 ip = mtod(m, struct ip *); \ 1385 } \ 1386 } while (0) 1387 1388 if (offset == 0) { 1389 switch (proto) { 1390 case IPPROTO_TCP: 1391 { 1392 struct tcphdr *tcp; 1393 1394 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1395 tcp = L3HDR(struct tcphdr, ip); 1396 dst_port = tcp->th_dport; 1397 src_port = tcp->th_sport; 1398 args->f_id.flags = tcp->th_flags; 1399 } 1400 break; 1401 1402 case IPPROTO_UDP: 1403 { 1404 struct udphdr *udp; 1405 1406 PULLUP_TO(hlen + sizeof(struct udphdr)); 1407 udp = L3HDR(struct udphdr, ip); 1408 dst_port = udp->uh_dport; 1409 src_port = udp->uh_sport; 1410 } 1411 break; 1412 1413 case IPPROTO_ICMP: 1414 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1415 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1416 break; 1417 1418 default: 1419 break; 1420 } 1421 #undef PULLUP_TO 1422 } 1423 1424 args->f_id.src_ip = ntohl(src_ip.s_addr); 1425 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1426 args->f_id.src_port = src_port = ntohs(src_port); 1427 args->f_id.dst_port = dst_port = ntohs(dst_port); 1428 1429 after_ip_checks: 1430 if (args->rule) { 1431 /* 1432 * Packet has already been tagged. Look for the next rule 1433 * to restart processing. 1434 * 1435 * If fw_one_pass != 0 then just accept it. 1436 * XXX should not happen here, but optimized out in 1437 * the caller. 1438 */ 1439 if (fw_one_pass) 1440 return 0; 1441 1442 f = args->rule->next_rule; 1443 if (f == NULL) 1444 f = lookup_next_rule(args->rule); 1445 } else { 1446 /* 1447 * Find the starting rule. It can be either the first 1448 * one, or the one after divert_rule if asked so. 1449 */ 1450 int skipto = args->divert_rule; 1451 1452 f = layer3_chain; 1453 if (args->eh == NULL && skipto != 0) { 1454 if (skipto >= IPFW_DEFAULT_RULE) 1455 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1456 while (f && f->rulenum <= skipto) 1457 f = f->next; 1458 if (f == NULL) /* drop packet */ 1459 return(IP_FW_PORT_DENY_FLAG); 1460 } 1461 } 1462 args->divert_rule = 0; /* reset to avoid confusion later */ 1463 1464 /* 1465 * Now scan the rules, and parse microinstructions for each rule. 1466 */ 1467 for (; f; f = f->next) { 1468 int l, cmdlen; 1469 ipfw_insn *cmd; 1470 int skip_or; /* skip rest of OR block */ 1471 1472 again: 1473 if (set_disable & (1 << f->set) ) 1474 continue; 1475 1476 skip_or = 0; 1477 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1478 l -= cmdlen, cmd += cmdlen) { 1479 int match; 1480 1481 /* 1482 * check_body is a jump target used when we find a 1483 * CHECK_STATE, and need to jump to the body of 1484 * the target rule. 1485 */ 1486 1487 check_body: 1488 cmdlen = F_LEN(cmd); 1489 /* 1490 * An OR block (insn_1 || .. || insn_n) has the 1491 * F_OR bit set in all but the last instruction. 1492 * The first match will set "skip_or", and cause 1493 * the following instructions to be skipped until 1494 * past the one with the F_OR bit clear. 1495 */ 1496 if (skip_or) { /* skip this instruction */ 1497 if ((cmd->len & F_OR) == 0) 1498 skip_or = 0; /* next one is good */ 1499 continue; 1500 } 1501 match = 0; /* set to 1 if we succeed */ 1502 1503 switch (cmd->opcode) { 1504 /* 1505 * The first set of opcodes compares the packet's 1506 * fields with some pattern, setting 'match' if a 1507 * match is found. At the end of the loop there is 1508 * logic to deal with F_NOT and F_OR flags associated 1509 * with the opcode. 1510 */ 1511 case O_NOP: 1512 match = 1; 1513 break; 1514 1515 case O_FORWARD_MAC: 1516 printf("ipfw: opcode %d unimplemented\n", 1517 cmd->opcode); 1518 break; 1519 1520 case O_GID: 1521 case O_UID: 1522 /* 1523 * We only check offset == 0 && proto != 0, 1524 * as this ensures that we have an IPv4 1525 * packet with the ports info. 1526 */ 1527 if (offset!=0) 1528 break; 1529 { 1530 struct inpcbinfo *pi; 1531 int wildcard; 1532 struct inpcb *pcb; 1533 1534 if (proto == IPPROTO_TCP) { 1535 wildcard = 0; 1536 pi = &tcbinfo; 1537 } else if (proto == IPPROTO_UDP) { 1538 wildcard = 1; 1539 pi = &udbinfo; 1540 } else 1541 break; 1542 1543 pcb = (oif) ? 1544 in_pcblookup_hash(pi, 1545 dst_ip, htons(dst_port), 1546 src_ip, htons(src_port), 1547 wildcard, oif) : 1548 in_pcblookup_hash(pi, 1549 src_ip, htons(src_port), 1550 dst_ip, htons(dst_port), 1551 wildcard, NULL); 1552 1553 if (pcb == NULL || pcb->inp_socket == NULL) 1554 break; 1555 #if __FreeBSD_version < 500034 1556 #define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1557 #endif 1558 if (cmd->opcode == O_UID) { 1559 match = 1560 !socheckuid(pcb->inp_socket, 1561 (uid_t)((ipfw_insn_u32 *)cmd)->d[0]); 1562 } else { 1563 match = groupmember( 1564 (uid_t)((ipfw_insn_u32 *)cmd)->d[0], 1565 pcb->inp_socket->so_cred); 1566 } 1567 } 1568 break; 1569 1570 case O_RECV: 1571 match = iface_match(m->m_pkthdr.rcvif, 1572 (ipfw_insn_if *)cmd); 1573 break; 1574 1575 case O_XMIT: 1576 match = iface_match(oif, (ipfw_insn_if *)cmd); 1577 break; 1578 1579 case O_VIA: 1580 match = iface_match(oif ? oif : 1581 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1582 break; 1583 1584 case O_MACADDR2: 1585 if (args->eh != NULL) { /* have MAC header */ 1586 u_int32_t *want = (u_int32_t *) 1587 ((ipfw_insn_mac *)cmd)->addr; 1588 u_int32_t *mask = (u_int32_t *) 1589 ((ipfw_insn_mac *)cmd)->mask; 1590 u_int32_t *hdr = (u_int32_t *)args->eh; 1591 1592 match = 1593 ( want[0] == (hdr[0] & mask[0]) && 1594 want[1] == (hdr[1] & mask[1]) && 1595 want[2] == (hdr[2] & mask[2]) ); 1596 } 1597 break; 1598 1599 case O_MAC_TYPE: 1600 if (args->eh != NULL) { 1601 u_int16_t t = 1602 ntohs(args->eh->ether_type); 1603 u_int16_t *p = 1604 ((ipfw_insn_u16 *)cmd)->ports; 1605 int i; 1606 1607 for (i = cmdlen - 1; !match && i>0; 1608 i--, p += 2) 1609 match = (t>=p[0] && t<=p[1]); 1610 } 1611 break; 1612 1613 case O_FRAG: 1614 match = (hlen > 0 && offset != 0); 1615 break; 1616 1617 case O_IN: /* "out" is "not in" */ 1618 match = (oif == NULL); 1619 break; 1620 1621 case O_LAYER2: 1622 match = (args->eh != NULL); 1623 break; 1624 1625 case O_PROTO: 1626 /* 1627 * We do not allow an arg of 0 so the 1628 * check of "proto" only suffices. 1629 */ 1630 match = (proto == cmd->arg1); 1631 break; 1632 1633 case O_IP_SRC: 1634 match = (hlen > 0 && 1635 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1636 src_ip.s_addr); 1637 break; 1638 1639 case O_IP_SRC_MASK: 1640 match = (hlen > 0 && 1641 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1642 (src_ip.s_addr & 1643 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1644 break; 1645 1646 case O_IP_SRC_ME: 1647 if (hlen > 0) { 1648 struct ifnet *tif; 1649 1650 INADDR_TO_IFP(src_ip, tif); 1651 match = (tif != NULL); 1652 } 1653 break; 1654 1655 case O_IP_DST_SET: 1656 case O_IP_SRC_SET: 1657 if (hlen > 0) { 1658 u_int32_t *d = (u_int32_t *)(cmd+1); 1659 u_int32_t addr = 1660 cmd->opcode == O_IP_DST_SET ? 1661 args->f_id.dst_ip : 1662 args->f_id.src_ip; 1663 1664 if (addr < d[0]) 1665 break; 1666 addr -= d[0]; /* subtract base */ 1667 match = (addr < cmd->arg1) && 1668 ( d[ 1 + (addr>>5)] & 1669 (1<<(addr & 0x1f)) ); 1670 } 1671 break; 1672 1673 case O_IP_DST: 1674 match = (hlen > 0 && 1675 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1676 dst_ip.s_addr); 1677 break; 1678 1679 case O_IP_DST_MASK: 1680 match = (hlen > 0) && 1681 (((ipfw_insn_ip *)cmd)->addr.s_addr == 1682 (dst_ip.s_addr & 1683 ((ipfw_insn_ip *)cmd)->mask.s_addr)); 1684 break; 1685 1686 case O_IP_DST_ME: 1687 if (hlen > 0) { 1688 struct ifnet *tif; 1689 1690 INADDR_TO_IFP(dst_ip, tif); 1691 match = (tif != NULL); 1692 } 1693 break; 1694 1695 case O_IP_SRCPORT: 1696 case O_IP_DSTPORT: 1697 /* 1698 * offset == 0 && proto != 0 is enough 1699 * to guarantee that we have an IPv4 1700 * packet with port info. 1701 */ 1702 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1703 && offset == 0) { 1704 u_int16_t x = 1705 (cmd->opcode == O_IP_SRCPORT) ? 1706 src_port : dst_port ; 1707 u_int16_t *p = 1708 ((ipfw_insn_u16 *)cmd)->ports; 1709 int i; 1710 1711 for (i = cmdlen - 1; !match && i>0; 1712 i--, p += 2) 1713 match = (x>=p[0] && x<=p[1]); 1714 } 1715 break; 1716 1717 case O_ICMPTYPE: 1718 match = (offset == 0 && proto==IPPROTO_ICMP && 1719 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1720 break; 1721 1722 case O_IPOPT: 1723 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1724 break; 1725 1726 case O_IPVER: 1727 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1728 break; 1729 1730 case O_IPTTL: 1731 match = (hlen > 0 && cmd->arg1 == ip->ip_ttl); 1732 break; 1733 1734 case O_IPID: 1735 match = (hlen > 0 && 1736 cmd->arg1 == ntohs(ip->ip_id)); 1737 break; 1738 1739 case O_IPLEN: 1740 match = (hlen > 0 && cmd->arg1 == ip_len); 1741 break; 1742 1743 case O_IPPRECEDENCE: 1744 match = (hlen > 0 && 1745 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1746 break; 1747 1748 case O_IPTOS: 1749 match = (hlen > 0 && 1750 flags_match(cmd, ip->ip_tos)); 1751 break; 1752 1753 case O_TCPFLAGS: 1754 match = (proto == IPPROTO_TCP && offset == 0 && 1755 flags_match(cmd, 1756 L3HDR(struct tcphdr,ip)->th_flags)); 1757 break; 1758 1759 case O_TCPOPTS: 1760 match = (proto == IPPROTO_TCP && offset == 0 && 1761 tcpopts_match(ip, cmd)); 1762 break; 1763 1764 case O_TCPSEQ: 1765 match = (proto == IPPROTO_TCP && offset == 0 && 1766 ((ipfw_insn_u32 *)cmd)->d[0] == 1767 L3HDR(struct tcphdr,ip)->th_seq); 1768 break; 1769 1770 case O_TCPACK: 1771 match = (proto == IPPROTO_TCP && offset == 0 && 1772 ((ipfw_insn_u32 *)cmd)->d[0] == 1773 L3HDR(struct tcphdr,ip)->th_ack); 1774 break; 1775 1776 case O_TCPWIN: 1777 match = (proto == IPPROTO_TCP && offset == 0 && 1778 cmd->arg1 == 1779 L3HDR(struct tcphdr,ip)->th_win); 1780 break; 1781 1782 case O_ESTAB: 1783 /* reject packets which have SYN only */ 1784 /* XXX should i also check for TH_ACK ? */ 1785 match = (proto == IPPROTO_TCP && offset == 0 && 1786 (L3HDR(struct tcphdr,ip)->th_flags & 1787 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1788 break; 1789 1790 case O_LOG: 1791 if (fw_verbose) 1792 ipfw_log(f, hlen, args->eh, m, oif); 1793 match = 1; 1794 break; 1795 1796 case O_PROB: 1797 match = (random()<((ipfw_insn_u32 *)cmd)->d[0]); 1798 break; 1799 1800 case O_VERREVPATH: 1801 /* Outgoing packets automatically pass/match */ 1802 match = ((oif != NULL) || 1803 (m->m_pkthdr.rcvif == NULL) || 1804 verify_rev_path(src_ip, m->m_pkthdr.rcvif)); 1805 break; 1806 1807 /* 1808 * The second set of opcodes represents 'actions', 1809 * i.e. the terminal part of a rule once the packet 1810 * matches all previous patterns. 1811 * Typically there is only one action for each rule, 1812 * and the opcode is stored at the end of the rule 1813 * (but there are exceptions -- see below). 1814 * 1815 * In general, here we set retval and terminate the 1816 * outer loop (would be a 'break 3' in some language, 1817 * but we need to do a 'goto done'). 1818 * 1819 * Exceptions: 1820 * O_COUNT and O_SKIPTO actions: 1821 * instead of terminating, we jump to the next rule 1822 * ('goto next_rule', equivalent to a 'break 2'), 1823 * or to the SKIPTO target ('goto again' after 1824 * having set f, cmd and l), respectively. 1825 * 1826 * O_LIMIT and O_KEEP_STATE: these opcodes are 1827 * not real 'actions', and are stored right 1828 * before the 'action' part of the rule. 1829 * These opcodes try to install an entry in the 1830 * state tables; if successful, we continue with 1831 * the next opcode (match=1; break;), otherwise 1832 * the packet * must be dropped 1833 * ('goto done' after setting retval); 1834 * 1835 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1836 * cause a lookup of the state table, and a jump 1837 * to the 'action' part of the parent rule 1838 * ('goto check_body') if an entry is found, or 1839 * (CHECK_STATE only) a jump to the next rule if 1840 * the entry is not found ('goto next_rule'). 1841 * The result of the lookup is cached to make 1842 * further instances of these opcodes are 1843 * effectively NOPs. 1844 */ 1845 case O_LIMIT: 1846 case O_KEEP_STATE: 1847 if (install_state(f, 1848 (ipfw_insn_limit *)cmd, args)) { 1849 retval = IP_FW_PORT_DENY_FLAG; 1850 goto done; /* error/limit violation */ 1851 } 1852 match = 1; 1853 break; 1854 1855 case O_PROBE_STATE: 1856 case O_CHECK_STATE: 1857 /* 1858 * dynamic rules are checked at the first 1859 * keep-state or check-state occurrence, 1860 * with the result being stored in dyn_dir. 1861 * The compiler introduces a PROBE_STATE 1862 * instruction for us when we have a 1863 * KEEP_STATE (because PROBE_STATE needs 1864 * to be run first). 1865 */ 1866 if (dyn_dir == MATCH_UNKNOWN && 1867 (q = lookup_dyn_rule(&args->f_id, 1868 &dyn_dir, proto == IPPROTO_TCP ? 1869 L3HDR(struct tcphdr, ip) : NULL)) 1870 != NULL) { 1871 /* 1872 * Found dynamic entry, update stats 1873 * and jump to the 'action' part of 1874 * the parent rule. 1875 */ 1876 q->pcnt++; 1877 q->bcnt += ip_len; 1878 f = q->rule; 1879 cmd = ACTION_PTR(f); 1880 l = f->cmd_len - f->act_ofs; 1881 goto check_body; 1882 } 1883 /* 1884 * Dynamic entry not found. If CHECK_STATE, 1885 * skip to next rule, if PROBE_STATE just 1886 * ignore and continue with next opcode. 1887 */ 1888 if (cmd->opcode == O_CHECK_STATE) 1889 goto next_rule; 1890 match = 1; 1891 break; 1892 1893 case O_ACCEPT: 1894 retval = 0; /* accept */ 1895 goto done; 1896 1897 case O_PIPE: 1898 case O_QUEUE: 1899 args->rule = f; /* report matching rule */ 1900 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 1901 goto done; 1902 1903 case O_DIVERT: 1904 case O_TEE: 1905 if (args->eh) /* not on layer 2 */ 1906 break; 1907 args->divert_rule = f->rulenum; 1908 retval = (cmd->opcode == O_DIVERT) ? 1909 cmd->arg1 : 1910 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 1911 goto done; 1912 1913 case O_COUNT: 1914 case O_SKIPTO: 1915 f->pcnt++; /* update stats */ 1916 f->bcnt += ip_len; 1917 f->timestamp = time_second; 1918 if (cmd->opcode == O_COUNT) 1919 goto next_rule; 1920 /* handle skipto */ 1921 if (f->next_rule == NULL) 1922 lookup_next_rule(f); 1923 f = f->next_rule; 1924 goto again; 1925 1926 case O_REJECT: 1927 /* 1928 * Drop the packet and send a reject notice 1929 * if the packet is not ICMP (or is an ICMP 1930 * query), and it is not multicast/broadcast. 1931 */ 1932 if (hlen > 0 && 1933 (proto != IPPROTO_ICMP || 1934 is_icmp_query(ip)) && 1935 !(m->m_flags & (M_BCAST|M_MCAST)) && 1936 !IN_MULTICAST(dst_ip.s_addr)) { 1937 send_reject(args, cmd->arg1, 1938 offset,ip_len); 1939 m = args->m; 1940 } 1941 /* FALLTHROUGH */ 1942 case O_DENY: 1943 retval = IP_FW_PORT_DENY_FLAG; 1944 goto done; 1945 1946 case O_FORWARD_IP: 1947 if (args->eh) /* not valid on layer2 pkts */ 1948 break; 1949 if (!q || dyn_dir == MATCH_FORWARD) 1950 args->next_hop = 1951 &((ipfw_insn_sa *)cmd)->sa; 1952 retval = 0; 1953 goto done; 1954 1955 default: 1956 panic("-- unknown opcode %d\n", cmd->opcode); 1957 } /* end of switch() on opcodes */ 1958 1959 if (cmd->len & F_NOT) 1960 match = !match; 1961 1962 if (match) { 1963 if (cmd->len & F_OR) 1964 skip_or = 1; 1965 } else { 1966 if (!(cmd->len & F_OR)) /* not an OR block, */ 1967 break; /* try next rule */ 1968 } 1969 1970 } /* end of inner for, scan opcodes */ 1971 1972 next_rule:; /* try next rule */ 1973 1974 } /* end of outer for, scan rules */ 1975 printf("ipfw: ouch!, skip past end of rules, denying packet\n"); 1976 return(IP_FW_PORT_DENY_FLAG); 1977 1978 done: 1979 /* Update statistics */ 1980 f->pcnt++; 1981 f->bcnt += ip_len; 1982 f->timestamp = time_second; 1983 return retval; 1984 1985 pullup_failed: 1986 if (fw_verbose) 1987 printf("ipfw: pullup failed\n"); 1988 return(IP_FW_PORT_DENY_FLAG); 1989 } 1990 1991 /* 1992 * When a rule is added/deleted, clear the next_rule pointers in all rules. 1993 * These will be reconstructed on the fly as packets are matched. 1994 * Must be called at splimp(). 1995 */ 1996 static void 1997 flush_rule_ptrs(void) 1998 { 1999 struct ip_fw *rule; 2000 2001 for (rule = layer3_chain; rule; rule = rule->next) 2002 rule->next_rule = NULL; 2003 } 2004 2005 /* 2006 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 2007 * pipe/queue, or to all of them (match == NULL). 2008 * Must be called at splimp(). 2009 */ 2010 void 2011 flush_pipe_ptrs(struct dn_flow_set *match) 2012 { 2013 struct ip_fw *rule; 2014 2015 for (rule = layer3_chain; rule; rule = rule->next) { 2016 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 2017 2018 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 2019 continue; 2020 /* 2021 * XXX Use bcmp/bzero to handle pipe_ptr to overcome 2022 * possible alignment problems on 64-bit architectures. 2023 * This code is seldom used so we do not worry too 2024 * much about efficiency. 2025 */ 2026 if (match == NULL || 2027 !bcmp(&cmd->pipe_ptr, &match, sizeof(match)) ) 2028 bzero(&cmd->pipe_ptr, sizeof(cmd->pipe_ptr)); 2029 } 2030 } 2031 2032 /* 2033 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 2034 * possibly create a rule number and add the rule to the list. 2035 * Update the rule_number in the input struct so the caller knows it as well. 2036 */ 2037 static int 2038 add_rule(struct ip_fw **head, struct ip_fw *input_rule) 2039 { 2040 struct ip_fw *rule, *f, *prev; 2041 int s; 2042 int l = RULESIZE(input_rule); 2043 2044 if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 2045 return (EINVAL); 2046 2047 rule = malloc(l, M_IPFW, M_NOWAIT | M_ZERO); 2048 if (rule == NULL) 2049 return (ENOSPC); 2050 2051 bcopy(input_rule, rule, l); 2052 2053 rule->next = NULL; 2054 rule->next_rule = NULL; 2055 2056 rule->pcnt = 0; 2057 rule->bcnt = 0; 2058 rule->timestamp = 0; 2059 2060 s = splimp(); 2061 2062 if (*head == NULL) { /* default rule */ 2063 *head = rule; 2064 goto done; 2065 } 2066 2067 /* 2068 * If rulenum is 0, find highest numbered rule before the 2069 * default rule, and add autoinc_step 2070 */ 2071 if (autoinc_step < 1) 2072 autoinc_step = 1; 2073 else if (autoinc_step > 1000) 2074 autoinc_step = 1000; 2075 if (rule->rulenum == 0) { 2076 /* 2077 * locate the highest numbered rule before default 2078 */ 2079 for (f = *head; f; f = f->next) { 2080 if (f->rulenum == IPFW_DEFAULT_RULE) 2081 break; 2082 rule->rulenum = f->rulenum; 2083 } 2084 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2085 rule->rulenum += autoinc_step; 2086 input_rule->rulenum = rule->rulenum; 2087 } 2088 2089 /* 2090 * Now insert the new rule in the right place in the sorted list. 2091 */ 2092 for (prev = NULL, f = *head; f; prev = f, f = f->next) { 2093 if (f->rulenum > rule->rulenum) { /* found the location */ 2094 if (prev) { 2095 rule->next = f; 2096 prev->next = rule; 2097 } else { /* head insert */ 2098 rule->next = *head; 2099 *head = rule; 2100 } 2101 break; 2102 } 2103 } 2104 flush_rule_ptrs(); 2105 done: 2106 static_count++; 2107 static_len += l; 2108 splx(s); 2109 DEB(printf("ipfw: installed rule %d, static count now %d\n", 2110 rule->rulenum, static_count);) 2111 return (0); 2112 } 2113 2114 /** 2115 * Free storage associated with a static rule (including derived 2116 * dynamic rules). 2117 * The caller is in charge of clearing rule pointers to avoid 2118 * dangling pointers. 2119 * @return a pointer to the next entry. 2120 * Arguments are not checked, so they better be correct. 2121 * Must be called at splimp(). 2122 */ 2123 static struct ip_fw * 2124 delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) 2125 { 2126 struct ip_fw *n; 2127 int l = RULESIZE(rule); 2128 2129 n = rule->next; 2130 remove_dyn_rule(rule, NULL /* force removal */); 2131 if (prev == NULL) 2132 *head = n; 2133 else 2134 prev->next = n; 2135 static_count--; 2136 static_len -= l; 2137 2138 if (DUMMYNET_LOADED) 2139 ip_dn_ruledel_ptr(rule); 2140 free(rule, M_IPFW); 2141 return n; 2142 } 2143 2144 /* 2145 * Deletes all rules from a chain (including the default rule 2146 * if the second argument is set). 2147 * Must be called at splimp(). 2148 */ 2149 static void 2150 free_chain(struct ip_fw **chain, int kill_default) 2151 { 2152 struct ip_fw *rule; 2153 2154 flush_rule_ptrs(); /* more efficient to do outside the loop */ 2155 2156 while ( (rule = *chain) != NULL && 2157 (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) 2158 delete_rule(chain, NULL, rule); 2159 } 2160 2161 /** 2162 * Remove all rules with given number, and also do set manipulation. 2163 * 2164 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2165 * the next 8 bits are the new set, the top 8 bits are the command: 2166 * 2167 * 0 delete rules with given number 2168 * 1 delete rules with given set number 2169 * 2 move rules with given number to new set 2170 * 3 move rules with given set number to new set 2171 * 4 swap sets with given numbers 2172 */ 2173 static int 2174 del_entry(struct ip_fw **chain, u_int32_t arg) 2175 { 2176 struct ip_fw *prev, *rule; 2177 int s; 2178 u_int16_t rulenum; 2179 u_int8_t cmd, new_set; 2180 2181 rulenum = arg & 0xffff; 2182 cmd = (arg >> 24) & 0xff; 2183 new_set = (arg >> 16) & 0xff; 2184 2185 if (cmd > 4) 2186 return EINVAL; 2187 if (new_set > 30) 2188 return EINVAL; 2189 if (cmd == 0 || cmd == 2) { 2190 if (rulenum == IPFW_DEFAULT_RULE) 2191 return EINVAL; 2192 } else { 2193 if (rulenum > 30) 2194 return EINVAL; 2195 } 2196 2197 switch (cmd) { 2198 case 0: /* delete rules with given number */ 2199 /* 2200 * locate first rule to delete 2201 */ 2202 for (prev = NULL, rule = *chain; 2203 rule && rule->rulenum < rulenum; 2204 prev = rule, rule = rule->next) 2205 ; 2206 if (rule->rulenum != rulenum) 2207 return EINVAL; 2208 2209 s = splimp(); /* no access to rules while removing */ 2210 /* 2211 * flush pointers outside the loop, then delete all matching 2212 * rules. prev remains the same throughout the cycle. 2213 */ 2214 flush_rule_ptrs(); 2215 while (rule && rule->rulenum == rulenum) 2216 rule = delete_rule(chain, prev, rule); 2217 splx(s); 2218 break; 2219 2220 case 1: /* delete all rules with given set number */ 2221 s = splimp(); 2222 flush_rule_ptrs(); 2223 for (prev = NULL, rule = *chain; rule ; ) 2224 if (rule->set == rulenum) 2225 rule = delete_rule(chain, prev, rule); 2226 else { 2227 prev = rule; 2228 rule = rule->next; 2229 } 2230 splx(s); 2231 break; 2232 2233 case 2: /* move rules with given number to new set */ 2234 s = splimp(); 2235 for (rule = *chain; rule ; rule = rule->next) 2236 if (rule->rulenum == rulenum) 2237 rule->set = new_set; 2238 splx(s); 2239 break; 2240 2241 case 3: /* move rules with given set number to new set */ 2242 s = splimp(); 2243 for (rule = *chain; rule ; rule = rule->next) 2244 if (rule->set == rulenum) 2245 rule->set = new_set; 2246 splx(s); 2247 break; 2248 2249 case 4: /* swap two sets */ 2250 s = splimp(); 2251 for (rule = *chain; rule ; rule = rule->next) 2252 if (rule->set == rulenum) 2253 rule->set = new_set; 2254 else if (rule->set == new_set) 2255 rule->set = rulenum; 2256 splx(s); 2257 break; 2258 } 2259 return 0; 2260 } 2261 2262 /* 2263 * Clear counters for a specific rule. 2264 */ 2265 static void 2266 clear_counters(struct ip_fw *rule, int log_only) 2267 { 2268 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2269 2270 if (log_only == 0) { 2271 rule->bcnt = rule->pcnt = 0; 2272 rule->timestamp = 0; 2273 } 2274 if (l->o.opcode == O_LOG) 2275 l->log_left = l->max_log; 2276 } 2277 2278 /** 2279 * Reset some or all counters on firewall rules. 2280 * @arg frwl is null to clear all entries, or contains a specific 2281 * rule number. 2282 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2283 */ 2284 static int 2285 zero_entry(int rulenum, int log_only) 2286 { 2287 struct ip_fw *rule; 2288 int s; 2289 char *msg; 2290 2291 if (rulenum == 0) { 2292 s = splimp(); 2293 norule_counter = 0; 2294 for (rule = layer3_chain; rule; rule = rule->next) 2295 clear_counters(rule, log_only); 2296 splx(s); 2297 msg = log_only ? "ipfw: All logging counts reset.\n" : 2298 "ipfw: Accounting cleared.\n"; 2299 } else { 2300 int cleared = 0; 2301 /* 2302 * We can have multiple rules with the same number, so we 2303 * need to clear them all. 2304 */ 2305 for (rule = layer3_chain; rule; rule = rule->next) 2306 if (rule->rulenum == rulenum) { 2307 s = splimp(); 2308 while (rule && rule->rulenum == rulenum) { 2309 clear_counters(rule, log_only); 2310 rule = rule->next; 2311 } 2312 splx(s); 2313 cleared = 1; 2314 break; 2315 } 2316 if (!cleared) /* we did not find any matching rules */ 2317 return (EINVAL); 2318 msg = log_only ? "ipfw: Entry %d logging count reset.\n" : 2319 "ipfw: Entry %d cleared.\n"; 2320 } 2321 if (fw_verbose) 2322 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); 2323 return (0); 2324 } 2325 2326 /* 2327 * Check validity of the structure before insert. 2328 * Fortunately rules are simple, so this mostly need to check rule sizes. 2329 */ 2330 static int 2331 check_ipfw_struct(struct ip_fw *rule, int size) 2332 { 2333 int l, cmdlen = 0; 2334 int have_action=0; 2335 ipfw_insn *cmd; 2336 2337 if (size < sizeof(*rule)) { 2338 printf("ipfw: rule too short\n"); 2339 return (EINVAL); 2340 } 2341 /* first, check for valid size */ 2342 l = RULESIZE(rule); 2343 if (l != size) { 2344 printf("ipfw: size mismatch (have %d want %d)\n", size, l); 2345 return (EINVAL); 2346 } 2347 /* 2348 * Now go for the individual checks. Very simple ones, basically only 2349 * instruction sizes. 2350 */ 2351 for (l = rule->cmd_len, cmd = rule->cmd ; 2352 l > 0 ; l -= cmdlen, cmd += cmdlen) { 2353 cmdlen = F_LEN(cmd); 2354 if (cmdlen > l) { 2355 printf("ipfw: opcode %d size truncated\n", 2356 cmd->opcode); 2357 return EINVAL; 2358 } 2359 DEB(printf("ipfw: opcode %d\n", cmd->opcode);) 2360 switch (cmd->opcode) { 2361 case O_NOP: 2362 case O_PROBE_STATE: 2363 case O_KEEP_STATE: 2364 case O_PROTO: 2365 case O_IP_SRC_ME: 2366 case O_IP_DST_ME: 2367 case O_LAYER2: 2368 case O_IN: 2369 case O_FRAG: 2370 case O_IPOPT: 2371 case O_IPLEN: 2372 case O_IPID: 2373 case O_IPTOS: 2374 case O_IPPRECEDENCE: 2375 case O_IPTTL: 2376 case O_IPVER: 2377 case O_TCPWIN: 2378 case O_TCPFLAGS: 2379 case O_TCPOPTS: 2380 case O_ESTAB: 2381 case O_VERREVPATH: 2382 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2383 goto bad_size; 2384 break; 2385 2386 case O_UID: 2387 case O_GID: 2388 case O_IP_SRC: 2389 case O_IP_DST: 2390 case O_TCPSEQ: 2391 case O_TCPACK: 2392 case O_PROB: 2393 case O_ICMPTYPE: 2394 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) 2395 goto bad_size; 2396 break; 2397 2398 case O_LIMIT: 2399 if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) 2400 goto bad_size; 2401 break; 2402 2403 case O_LOG: 2404 if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) 2405 goto bad_size; 2406 2407 ((ipfw_insn_log *)cmd)->log_left = 2408 ((ipfw_insn_log *)cmd)->max_log; 2409 2410 break; 2411 2412 case O_IP_SRC_MASK: 2413 case O_IP_DST_MASK: 2414 if (cmdlen != F_INSN_SIZE(ipfw_insn_ip)) 2415 goto bad_size; 2416 if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) { 2417 printf("ipfw: opcode %d, useless rule\n", 2418 cmd->opcode); 2419 return EINVAL; 2420 } 2421 break; 2422 2423 case O_IP_SRC_SET: 2424 case O_IP_DST_SET: 2425 if (cmd->arg1 == 0 || cmd->arg1 > 256) { 2426 printf("ipfw: invalid set size %d\n", 2427 cmd->arg1); 2428 return EINVAL; 2429 } 2430 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + 2431 (cmd->arg1+31)/32 ) 2432 goto bad_size; 2433 break; 2434 2435 case O_MACADDR2: 2436 if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) 2437 goto bad_size; 2438 break; 2439 2440 case O_MAC_TYPE: 2441 case O_IP_SRCPORT: 2442 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ 2443 if (cmdlen < 2 || cmdlen > 31) 2444 goto bad_size; 2445 break; 2446 2447 case O_RECV: 2448 case O_XMIT: 2449 case O_VIA: 2450 if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) 2451 goto bad_size; 2452 break; 2453 2454 case O_PIPE: 2455 case O_QUEUE: 2456 if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) 2457 goto bad_size; 2458 goto check_action; 2459 2460 case O_FORWARD_IP: 2461 if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) 2462 goto bad_size; 2463 goto check_action; 2464 2465 case O_FORWARD_MAC: /* XXX not implemented yet */ 2466 case O_CHECK_STATE: 2467 case O_COUNT: 2468 case O_ACCEPT: 2469 case O_DENY: 2470 case O_REJECT: 2471 case O_SKIPTO: 2472 case O_DIVERT: 2473 case O_TEE: 2474 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2475 goto bad_size; 2476 check_action: 2477 if (have_action) { 2478 printf("ipfw: opcode %d, multiple actions" 2479 " not allowed\n", 2480 cmd->opcode); 2481 return EINVAL; 2482 } 2483 have_action = 1; 2484 if (l != cmdlen) { 2485 printf("ipfw: opcode %d, action must be" 2486 " last opcode\n", 2487 cmd->opcode); 2488 return EINVAL; 2489 } 2490 break; 2491 default: 2492 printf("ipfw: opcode %d, unknown opcode\n", 2493 cmd->opcode); 2494 return EINVAL; 2495 } 2496 } 2497 if (have_action == 0) { 2498 printf("ipfw: missing action\n"); 2499 return EINVAL; 2500 } 2501 return 0; 2502 2503 bad_size: 2504 printf("ipfw: opcode %d size %d wrong\n", 2505 cmd->opcode, cmdlen); 2506 return EINVAL; 2507 } 2508 2509 2510 /** 2511 * {set|get}sockopt parser. 2512 */ 2513 static int 2514 ipfw_ctl(struct sockopt *sopt) 2515 { 2516 int error, s, rulenum; 2517 size_t size; 2518 struct ip_fw *bp , *buf, *rule; 2519 2520 static u_int32_t rule_buf[255]; /* we copy the data here */ 2521 2522 /* 2523 * Disallow modifications in really-really secure mode, but still allow 2524 * the logging counters to be reset. 2525 */ 2526 if (sopt->sopt_name == IP_FW_ADD || 2527 (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { 2528 #if __FreeBSD_version >= 500034 2529 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); 2530 if (error) 2531 return (error); 2532 #else /* FreeBSD 4.x */ 2533 if (securelevel >= 3) 2534 return (EPERM); 2535 #endif 2536 } 2537 2538 error = 0; 2539 2540 switch (sopt->sopt_name) { 2541 case IP_FW_GET: 2542 /* 2543 * pass up a copy of the current rules. Static rules 2544 * come first (the last of which has number IPFW_DEFAULT_RULE), 2545 * followed by a possibly empty list of dynamic rule. 2546 * The last dynamic rule has NULL in the "next" field. 2547 */ 2548 s = splimp(); 2549 size = static_len; /* size of static rules */ 2550 if (ipfw_dyn_v) /* add size of dyn.rules */ 2551 size += (dyn_count * sizeof(ipfw_dyn_rule)); 2552 2553 /* 2554 * XXX todo: if the user passes a short length just to know 2555 * how much room is needed, do not bother filling up the 2556 * buffer, just jump to the sooptcopyout. 2557 */ 2558 buf = malloc(size, M_TEMP, M_WAITOK); 2559 if (buf == 0) { 2560 splx(s); 2561 error = ENOBUFS; 2562 break; 2563 } 2564 2565 bp = buf; 2566 for (rule = layer3_chain; rule ; rule = rule->next) { 2567 int i = RULESIZE(rule); 2568 bcopy(rule, bp, i); 2569 bcopy(&set_disable, &(bp->next_rule), 2570 sizeof(set_disable)); 2571 bp = (struct ip_fw *)((char *)bp + i); 2572 } 2573 if (ipfw_dyn_v) { 2574 int i; 2575 ipfw_dyn_rule *p, *dst, *last = NULL; 2576 2577 dst = (ipfw_dyn_rule *)bp; 2578 for (i = 0 ; i < curr_dyn_buckets ; i++ ) 2579 for ( p = ipfw_dyn_v[i] ; p != NULL ; 2580 p = p->next, dst++ ) { 2581 bcopy(p, dst, sizeof *p); 2582 bcopy(&(p->rule->rulenum), &(dst->rule), 2583 sizeof(p->rule->rulenum)); 2584 /* 2585 * store a non-null value in "next". 2586 * The userland code will interpret a 2587 * NULL here as a marker 2588 * for the last dynamic rule. 2589 */ 2590 bcopy(&dst, &dst->next, sizeof(dst)); 2591 last = dst ; 2592 dst->expire = 2593 TIME_LEQ(dst->expire, time_second) ? 2594 0 : dst->expire - time_second ; 2595 } 2596 if (last != NULL) /* mark last dynamic rule */ 2597 bzero(&last->next, sizeof(last)); 2598 } 2599 splx(s); 2600 2601 error = sooptcopyout(sopt, buf, size); 2602 free(buf, M_TEMP); 2603 break; 2604 2605 case IP_FW_FLUSH: 2606 /* 2607 * Normally we cannot release the lock on each iteration. 2608 * We could do it here only because we start from the head all 2609 * the times so there is no risk of missing some entries. 2610 * On the other hand, the risk is that we end up with 2611 * a very inconsistent ruleset, so better keep the lock 2612 * around the whole cycle. 2613 * 2614 * XXX this code can be improved by resetting the head of 2615 * the list to point to the default rule, and then freeing 2616 * the old list without the need for a lock. 2617 */ 2618 2619 s = splimp(); 2620 free_chain(&layer3_chain, 0 /* keep default rule */); 2621 splx(s); 2622 break; 2623 2624 case IP_FW_ADD: 2625 rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ 2626 error = sooptcopyin(sopt, rule, sizeof(rule_buf), 2627 sizeof(struct ip_fw) ); 2628 size = sopt->sopt_valsize; 2629 if (error || (error = check_ipfw_struct(rule, size))) 2630 break; 2631 2632 error = add_rule(&layer3_chain, rule); 2633 size = RULESIZE(rule); 2634 if (!error && sopt->sopt_dir == SOPT_GET) 2635 error = sooptcopyout(sopt, rule, size); 2636 break; 2637 2638 case IP_FW_DEL: 2639 /* 2640 * IP_FW_DEL is used for deleting single rules or sets, 2641 * and (ab)used to atomically manipulate sets. Argument size 2642 * is used to distinguish between the two: 2643 * sizeof(u_int32_t) 2644 * delete single rule or set of rules, 2645 * or reassign rules (or sets) to a different set. 2646 * 2*sizeof(u_int32_t) 2647 * atomic disable/enable sets. 2648 * first u_int32_t contains sets to be disabled, 2649 * second u_int32_t contains sets to be enabled. 2650 */ 2651 error = sooptcopyin(sopt, rule_buf, 2652 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2653 if (error) 2654 break; 2655 size = sopt->sopt_valsize; 2656 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2657 error = del_entry(&layer3_chain, rule_buf[0]); 2658 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2659 set_disable = 2660 (set_disable | rule_buf[0]) & ~rule_buf[1] & 2661 ~(1<<31); /* set 31 always enabled */ 2662 else 2663 error = EINVAL; 2664 break; 2665 2666 case IP_FW_ZERO: 2667 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2668 rulenum=0; 2669 2670 if (sopt->sopt_val != 0) { 2671 error = sooptcopyin(sopt, &rulenum, 2672 sizeof(int), sizeof(int)); 2673 if (error) 2674 break; 2675 } 2676 error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); 2677 break; 2678 2679 default: 2680 printf("ipfw: ipfw_ctl invalid option %d\n", sopt->sopt_name); 2681 error = EINVAL; 2682 } 2683 2684 return (error); 2685 } 2686 2687 /** 2688 * dummynet needs a reference to the default rule, because rules can be 2689 * deleted while packets hold a reference to them. When this happens, 2690 * dummynet changes the reference to the default rule (it could well be a 2691 * NULL pointer, but this way we do not need to check for the special 2692 * case, plus here he have info on the default behaviour). 2693 */ 2694 struct ip_fw *ip_fw_default_rule; 2695 2696 /* 2697 * This procedure is only used to handle keepalives. It is invoked 2698 * every dyn_keepalive_period 2699 */ 2700 static void 2701 ipfw_tick(void * __unused unused) 2702 { 2703 int i; 2704 int s; 2705 ipfw_dyn_rule *q; 2706 2707 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2708 goto done; 2709 2710 s = splimp(); 2711 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2712 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2713 if (q->dyn_type == O_LIMIT_PARENT) 2714 continue; 2715 if (q->id.proto != IPPROTO_TCP) 2716 continue; 2717 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2718 continue; 2719 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2720 q->expire)) 2721 continue; /* too early */ 2722 if (TIME_LEQ(q->expire, time_second)) 2723 continue; /* too late, rule expired */ 2724 2725 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2726 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2727 } 2728 } 2729 splx(s); 2730 done: 2731 ipfw_timeout_h = timeout(ipfw_tick, NULL, dyn_keepalive_period*hz); 2732 } 2733 2734 static void 2735 ipfw_init(void) 2736 { 2737 struct ip_fw default_rule; 2738 2739 ip_fw_chk_ptr = ipfw_chk; 2740 ip_fw_ctl_ptr = ipfw_ctl; 2741 layer3_chain = NULL; 2742 2743 bzero(&default_rule, sizeof default_rule); 2744 2745 default_rule.act_ofs = 0; 2746 default_rule.rulenum = IPFW_DEFAULT_RULE; 2747 default_rule.cmd_len = 1; 2748 default_rule.set = 31; 2749 2750 default_rule.cmd[0].len = 1; 2751 default_rule.cmd[0].opcode = 2752 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2753 1 ? O_ACCEPT : 2754 #endif 2755 O_DENY; 2756 2757 add_rule(&layer3_chain, &default_rule); 2758 2759 ip_fw_default_rule = layer3_chain; 2760 printf("ipfw2 initialized, divert %s, " 2761 "rule-based forwarding enabled, default to %s, logging ", 2762 #ifdef IPDIVERT 2763 "enabled", 2764 #else 2765 "disabled", 2766 #endif 2767 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2768 2769 #ifdef IPFIREWALL_VERBOSE 2770 fw_verbose = 1; 2771 #endif 2772 #ifdef IPFIREWALL_VERBOSE_LIMIT 2773 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2774 #endif 2775 if (fw_verbose == 0) 2776 printf("disabled\n"); 2777 else if (verbose_limit == 0) 2778 printf("unlimited\n"); 2779 else 2780 printf("limited to %d packets/entry by default\n", 2781 verbose_limit); 2782 bzero(&ipfw_timeout_h, sizeof(struct callout_handle)); 2783 ipfw_timeout_h = timeout(ipfw_tick, NULL, hz); 2784 } 2785 2786 static int 2787 ipfw_modevent(module_t mod, int type, void *unused) 2788 { 2789 int s; 2790 int err = 0; 2791 2792 switch (type) { 2793 case MOD_LOAD: 2794 s = splimp(); 2795 if (IPFW_LOADED) { 2796 splx(s); 2797 printf("IP firewall already loaded\n"); 2798 err = EEXIST; 2799 } else { 2800 ipfw_init(); 2801 splx(s); 2802 } 2803 break; 2804 2805 case MOD_UNLOAD: 2806 #if !defined(KLD_MODULE) 2807 printf("ipfw statically compiled, cannot unload\n"); 2808 err = EBUSY; 2809 #else 2810 s = splimp(); 2811 untimeout(ipfw_tick, NULL, ipfw_timeout_h); 2812 ip_fw_chk_ptr = NULL; 2813 ip_fw_ctl_ptr = NULL; 2814 free_chain(&layer3_chain, 1 /* kill default rule */); 2815 splx(s); 2816 printf("IP firewall unloaded\n"); 2817 #endif 2818 break; 2819 default: 2820 break; 2821 } 2822 return err; 2823 } 2824 2825 static moduledata_t ipfwmod = { 2826 "ipfw", 2827 ipfw_modevent, 2828 0 2829 }; 2830 DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); 2831 MODULE_VERSION(ipfw, 1); 2832 #endif /* IPFW2 */
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