ip_fw2.c revision 123096
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: head/sys/netinet/ip_fw2.c 123096 2003-12-02 00:23:45Z sam $ 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#include "opt_ipsec.h" 41#ifndef INET 42#error IPFIREWALL requires INET. 43#endif /* INET */ 44#endif 45 46#define IPFW2 1 47#if IPFW2 48#include <sys/param.h> 49#include <sys/systm.h> 50#include <sys/malloc.h> 51#include <sys/mbuf.h> 52#include <sys/kernel.h> 53#include <sys/proc.h> 54#include <sys/socket.h> 55#include <sys/socketvar.h> 56#include <sys/sysctl.h> 57#include <sys/syslog.h> 58#include <sys/ucred.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 <netinet/ip_fw.h> 69#include <netinet/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#ifdef IPSEC 78#include <netinet6/ipsec.h> 79#endif 80 81#include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */ 82 83#include <machine/in_cksum.h> /* XXX for in_cksum */ 84 85/* 86 * This is used to avoid that a firewall-generated packet 87 * loops forever through the firewall. Note that it must 88 * be a flag that is unused by other protocols that might 89 * be called from ip_output (e.g. IPsec) and it must be 90 * listed in M_COPYFLAGS in mbuf.h so that if the mbuf chain 91 * is altered on the way through ip_output it is not lost. 92 * It might be better to add an m_tag since the this happens 93 * infrequently. 94 */ 95#define M_SKIP_FIREWALL M_PROTO6 96 97/* 98 * set_disable contains one bit per set value (0..31). 99 * If the bit is set, all rules with the corresponding set 100 * are disabled. Set RESVD_SET(31) is reserved for the default rule 101 * and rules that are not deleted by the flush command, 102 * and CANNOT be disabled. 103 * Rules in set RESVD_SET can only be deleted explicitly. 104 */ 105static u_int32_t set_disable; 106 107static int fw_verbose; 108static int verbose_limit; 109 110static struct callout ipfw_timeout; 111#define IPFW_DEFAULT_RULE 65535 112 113struct ip_fw_chain { 114 struct ip_fw *rules; /* list of rules */ 115 struct ip_fw *reap; /* list of rules to reap */ 116 struct mtx mtx; /* lock guarding rule list */ 117}; 118#define IPFW_LOCK_INIT(_chain) \ 119 mtx_init(&(_chain)->mtx, "IPFW static rules", NULL, \ 120 MTX_DEF | MTX_RECURSE) 121#define IPFW_LOCK_DESTROY(_chain) mtx_destroy(&(_chain)->mtx) 122#define IPFW_LOCK(_chain) mtx_lock(&(_chain)->mtx) 123#define IPFW_UNLOCK(_chain) mtx_unlock(&(_chain)->mtx) 124#define IPFW_LOCK_ASSERT(_chain) mtx_assert(&(_chain)->mtx, MA_OWNED) 125 126/* 127 * list of rules for layer 3 128 */ 129static struct ip_fw_chain layer3_chain; 130 131MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); 132 133static int fw_debug = 1; 134static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ 135 136#ifdef SYSCTL_NODE 137SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); 138SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, 139 CTLFLAG_RW | CTLFLAG_SECURE3, 140 &fw_enable, 0, "Enable ipfw"); 141SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW, 142 &autoinc_step, 0, "Rule number autincrement step"); 143SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, one_pass, 144 CTLFLAG_RW | CTLFLAG_SECURE3, 145 &fw_one_pass, 0, 146 "Only do a single pass through ipfw when using dummynet(4)"); 147SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, 148 &fw_debug, 0, "Enable printing of debug ip_fw statements"); 149SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, 150 CTLFLAG_RW | CTLFLAG_SECURE3, 151 &fw_verbose, 0, "Log matches to ipfw rules"); 152SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, 153 &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); 154 155/* 156 * Description of dynamic rules. 157 * 158 * Dynamic rules are stored in lists accessed through a hash table 159 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 160 * be modified through the sysctl variable dyn_buckets which is 161 * updated when the table becomes empty. 162 * 163 * XXX currently there is only one list, ipfw_dyn. 164 * 165 * When a packet is received, its address fields are first masked 166 * with the mask defined for the rule, then hashed, then matched 167 * against the entries in the corresponding list. 168 * Dynamic rules can be used for different purposes: 169 * + stateful rules; 170 * + enforcing limits on the number of sessions; 171 * + in-kernel NAT (not implemented yet) 172 * 173 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 174 * measured in seconds and depending on the flags. 175 * 176 * The total number of dynamic rules is stored in dyn_count. 177 * The max number of dynamic rules is dyn_max. When we reach 178 * the maximum number of rules we do not create anymore. This is 179 * done to avoid consuming too much memory, but also too much 180 * time when searching on each packet (ideally, we should try instead 181 * to put a limit on the length of the list on each bucket...). 182 * 183 * Each dynamic rule holds a pointer to the parent ipfw rule so 184 * we know what action to perform. Dynamic rules are removed when 185 * the parent rule is deleted. XXX we should make them survive. 186 * 187 * There are some limitations with dynamic rules -- we do not 188 * obey the 'randomized match', and we do not do multiple 189 * passes through the firewall. XXX check the latter!!! 190 */ 191static ipfw_dyn_rule **ipfw_dyn_v = NULL; 192static u_int32_t dyn_buckets = 256; /* must be power of 2 */ 193static u_int32_t curr_dyn_buckets = 256; /* must be power of 2 */ 194 195static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */ 196#define IPFW_DYN_LOCK_INIT() \ 197 mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF) 198#define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx) 199#define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx) 200#define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx) 201#define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED) 202 203/* 204 * Timeouts for various events in handing dynamic rules. 205 */ 206static u_int32_t dyn_ack_lifetime = 300; 207static u_int32_t dyn_syn_lifetime = 20; 208static u_int32_t dyn_fin_lifetime = 1; 209static u_int32_t dyn_rst_lifetime = 1; 210static u_int32_t dyn_udp_lifetime = 10; 211static u_int32_t dyn_short_lifetime = 5; 212 213/* 214 * Keepalives are sent if dyn_keepalive is set. They are sent every 215 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 216 * seconds of lifetime of a rule. 217 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 218 * than dyn_keepalive_period. 219 */ 220 221static u_int32_t dyn_keepalive_interval = 20; 222static u_int32_t dyn_keepalive_period = 5; 223static u_int32_t dyn_keepalive = 1; /* do send keepalives */ 224 225static u_int32_t static_count; /* # of static rules */ 226static u_int32_t static_len; /* size in bytes of static rules */ 227static u_int32_t dyn_count; /* # of dynamic rules */ 228static u_int32_t dyn_max = 4096; /* max # of dynamic rules */ 229 230SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, 231 &dyn_buckets, 0, "Number of dyn. buckets"); 232SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, 233 &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); 234SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, 235 &dyn_count, 0, "Number of dyn. rules"); 236SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, 237 &dyn_max, 0, "Max number of dyn. rules"); 238SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, 239 &static_count, 0, "Number of static rules"); 240SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, 241 &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); 242SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, 243 &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); 244SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, 245 &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); 246SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, 247 &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); 248SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, 249 &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); 250SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, 251 &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); 252SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, 253 &dyn_keepalive, 0, "Enable keepalives for dyn. rules"); 254 255#endif /* SYSCTL_NODE */ 256 257 258static ip_fw_chk_t ipfw_chk; 259 260ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ 261 262/* 263 * This macro maps an ip pointer into a layer3 header pointer of type T 264 */ 265#define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) 266 267static __inline int 268icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) 269{ 270 int type = L3HDR(struct icmp,ip)->icmp_type; 271 272 return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) ); 273} 274 275#define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \ 276 (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) ) 277 278static int 279is_icmp_query(struct ip *ip) 280{ 281 int type = L3HDR(struct icmp, ip)->icmp_type; 282 return (type <= ICMP_MAXTYPE && (TT & (1<<type)) ); 283} 284#undef TT 285 286/* 287 * The following checks use two arrays of 8 or 16 bits to store the 288 * bits that we want set or clear, respectively. They are in the 289 * low and high half of cmd->arg1 or cmd->d[0]. 290 * 291 * We scan options and store the bits we find set. We succeed if 292 * 293 * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear 294 * 295 * The code is sometimes optimized not to store additional variables. 296 */ 297 298static int 299flags_match(ipfw_insn *cmd, u_int8_t bits) 300{ 301 u_char want_clear; 302 bits = ~bits; 303 304 if ( ((cmd->arg1 & 0xff) & bits) != 0) 305 return 0; /* some bits we want set were clear */ 306 want_clear = (cmd->arg1 >> 8) & 0xff; 307 if ( (want_clear & bits) != want_clear) 308 return 0; /* some bits we want clear were set */ 309 return 1; 310} 311 312static int 313ipopts_match(struct ip *ip, ipfw_insn *cmd) 314{ 315 int optlen, bits = 0; 316 u_char *cp = (u_char *)(ip + 1); 317 int x = (ip->ip_hl << 2) - sizeof (struct ip); 318 319 for (; x > 0; x -= optlen, cp += optlen) { 320 int opt = cp[IPOPT_OPTVAL]; 321 322 if (opt == IPOPT_EOL) 323 break; 324 if (opt == IPOPT_NOP) 325 optlen = 1; 326 else { 327 optlen = cp[IPOPT_OLEN]; 328 if (optlen <= 0 || optlen > x) 329 return 0; /* invalid or truncated */ 330 } 331 switch (opt) { 332 333 default: 334 break; 335 336 case IPOPT_LSRR: 337 bits |= IP_FW_IPOPT_LSRR; 338 break; 339 340 case IPOPT_SSRR: 341 bits |= IP_FW_IPOPT_SSRR; 342 break; 343 344 case IPOPT_RR: 345 bits |= IP_FW_IPOPT_RR; 346 break; 347 348 case IPOPT_TS: 349 bits |= IP_FW_IPOPT_TS; 350 break; 351 } 352 } 353 return (flags_match(cmd, bits)); 354} 355 356static int 357tcpopts_match(struct ip *ip, ipfw_insn *cmd) 358{ 359 int optlen, bits = 0; 360 struct tcphdr *tcp = L3HDR(struct tcphdr,ip); 361 u_char *cp = (u_char *)(tcp + 1); 362 int x = (tcp->th_off << 2) - sizeof(struct tcphdr); 363 364 for (; x > 0; x -= optlen, cp += optlen) { 365 int opt = cp[0]; 366 if (opt == TCPOPT_EOL) 367 break; 368 if (opt == TCPOPT_NOP) 369 optlen = 1; 370 else { 371 optlen = cp[1]; 372 if (optlen <= 0) 373 break; 374 } 375 376 switch (opt) { 377 378 default: 379 break; 380 381 case TCPOPT_MAXSEG: 382 bits |= IP_FW_TCPOPT_MSS; 383 break; 384 385 case TCPOPT_WINDOW: 386 bits |= IP_FW_TCPOPT_WINDOW; 387 break; 388 389 case TCPOPT_SACK_PERMITTED: 390 case TCPOPT_SACK: 391 bits |= IP_FW_TCPOPT_SACK; 392 break; 393 394 case TCPOPT_TIMESTAMP: 395 bits |= IP_FW_TCPOPT_TS; 396 break; 397 398 case TCPOPT_CC: 399 case TCPOPT_CCNEW: 400 case TCPOPT_CCECHO: 401 bits |= IP_FW_TCPOPT_CC; 402 break; 403 } 404 } 405 return (flags_match(cmd, bits)); 406} 407 408static int 409iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) 410{ 411 if (ifp == NULL) /* no iface with this packet, match fails */ 412 return 0; 413 /* Check by name or by IP address */ 414 if (cmd->name[0] != '\0') { /* match by name */ 415 /* Check name */ 416 if (cmd->p.glob) { 417 if (fnmatch(cmd->name, ifp->if_xname, 0) == 0) 418 return(1); 419 } else { 420 if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) 421 return(1); 422 } 423 } else { 424 struct ifaddr *ia; 425 426 /* XXX lock? */ 427 TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 428 if (ia->ifa_addr == NULL) 429 continue; 430 if (ia->ifa_addr->sa_family != AF_INET) 431 continue; 432 if (cmd->p.ip.s_addr == ((struct sockaddr_in *) 433 (ia->ifa_addr))->sin_addr.s_addr) 434 return(1); /* match */ 435 } 436 } 437 return(0); /* no match, fail ... */ 438} 439 440/* 441 * The 'verrevpath' option checks that the interface that an IP packet 442 * arrives on is the same interface that traffic destined for the 443 * packet's source address would be routed out of. This is a measure 444 * to block forged packets. This is also commonly known as "anti-spoofing" 445 * or Unicast Reverse Path Forwarding (Unicast RFP) in Cisco-ese. The 446 * name of the knob is purposely reminisent of the Cisco IOS command, 447 * 448 * ip verify unicast reverse-path 449 * 450 * which implements the same functionality. But note that syntax is 451 * misleading. The check may be performed on all IP packets whether unicast, 452 * multicast, or broadcast. 453 */ 454static int 455verify_rev_path(struct in_addr src, struct ifnet *ifp) 456{ 457 struct route ro; 458 struct sockaddr_in *dst; 459 460 bzero(&ro, sizeof(ro)); 461 462 dst = (struct sockaddr_in *)&(ro.ro_dst); 463 dst->sin_family = AF_INET; 464 dst->sin_len = sizeof(*dst); 465 dst->sin_addr = src; 466 rtalloc_ign(&ro, RTF_CLONING); 467 468 if (ro.ro_rt == NULL) 469 return 0; 470 if ((ifp == NULL) || (ro.ro_rt->rt_ifp->if_index != ifp->if_index)) { 471 RTFREE(ro.ro_rt); 472 return 0; 473 } 474 RTFREE(ro.ro_rt); 475 return 1; 476} 477 478 479static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ 480 481#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 482#define SNP(buf) buf, sizeof(buf) 483 484/* 485 * We enter here when we have a rule with O_LOG. 486 * XXX this function alone takes about 2Kbytes of code! 487 */ 488static void 489ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, 490 struct mbuf *m, struct ifnet *oif) 491{ 492 char *action; 493 int limit_reached = 0; 494 char action2[40], proto[48], fragment[28]; 495 496 fragment[0] = '\0'; 497 proto[0] = '\0'; 498 499 if (f == NULL) { /* bogus pkt */ 500 if (verbose_limit != 0 && norule_counter >= verbose_limit) 501 return; 502 norule_counter++; 503 if (norule_counter == verbose_limit) 504 limit_reached = verbose_limit; 505 action = "Refuse"; 506 } else { /* O_LOG is the first action, find the real one */ 507 ipfw_insn *cmd = ACTION_PTR(f); 508 ipfw_insn_log *l = (ipfw_insn_log *)cmd; 509 510 if (l->max_log != 0 && l->log_left == 0) 511 return; 512 l->log_left--; 513 if (l->log_left == 0) 514 limit_reached = l->max_log; 515 cmd += F_LEN(cmd); /* point to first action */ 516 if (cmd->opcode == O_PROB) 517 cmd += F_LEN(cmd); 518 519 action = action2; 520 switch (cmd->opcode) { 521 case O_DENY: 522 action = "Deny"; 523 break; 524 525 case O_REJECT: 526 if (cmd->arg1==ICMP_REJECT_RST) 527 action = "Reset"; 528 else if (cmd->arg1==ICMP_UNREACH_HOST) 529 action = "Reject"; 530 else 531 snprintf(SNPARGS(action2, 0), "Unreach %d", 532 cmd->arg1); 533 break; 534 535 case O_ACCEPT: 536 action = "Accept"; 537 break; 538 case O_COUNT: 539 action = "Count"; 540 break; 541 case O_DIVERT: 542 snprintf(SNPARGS(action2, 0), "Divert %d", 543 cmd->arg1); 544 break; 545 case O_TEE: 546 snprintf(SNPARGS(action2, 0), "Tee %d", 547 cmd->arg1); 548 break; 549 case O_SKIPTO: 550 snprintf(SNPARGS(action2, 0), "SkipTo %d", 551 cmd->arg1); 552 break; 553 case O_PIPE: 554 snprintf(SNPARGS(action2, 0), "Pipe %d", 555 cmd->arg1); 556 break; 557 case O_QUEUE: 558 snprintf(SNPARGS(action2, 0), "Queue %d", 559 cmd->arg1); 560 break; 561 case O_FORWARD_IP: { 562 ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; 563 int len; 564 565 len = snprintf(SNPARGS(action2, 0), "Forward to %s", 566 inet_ntoa(sa->sa.sin_addr)); 567 if (sa->sa.sin_port) 568 snprintf(SNPARGS(action2, len), ":%d", 569 sa->sa.sin_port); 570 } 571 break; 572 default: 573 action = "UNKNOWN"; 574 break; 575 } 576 } 577 578 if (hlen == 0) { /* non-ip */ 579 snprintf(SNPARGS(proto, 0), "MAC"); 580 } else { 581 struct ip *ip = mtod(m, struct ip *); 582 /* these three are all aliases to the same thing */ 583 struct icmp *const icmp = L3HDR(struct icmp, ip); 584 struct tcphdr *const tcp = (struct tcphdr *)icmp; 585 struct udphdr *const udp = (struct udphdr *)icmp; 586 587 int ip_off, offset, ip_len; 588 589 int len; 590 591 if (eh != NULL) { /* layer 2 packets are as on the wire */ 592 ip_off = ntohs(ip->ip_off); 593 ip_len = ntohs(ip->ip_len); 594 } else { 595 ip_off = ip->ip_off; 596 ip_len = ip->ip_len; 597 } 598 offset = ip_off & IP_OFFMASK; 599 switch (ip->ip_p) { 600 case IPPROTO_TCP: 601 len = snprintf(SNPARGS(proto, 0), "TCP %s", 602 inet_ntoa(ip->ip_src)); 603 if (offset == 0) 604 snprintf(SNPARGS(proto, len), ":%d %s:%d", 605 ntohs(tcp->th_sport), 606 inet_ntoa(ip->ip_dst), 607 ntohs(tcp->th_dport)); 608 else 609 snprintf(SNPARGS(proto, len), " %s", 610 inet_ntoa(ip->ip_dst)); 611 break; 612 613 case IPPROTO_UDP: 614 len = snprintf(SNPARGS(proto, 0), "UDP %s", 615 inet_ntoa(ip->ip_src)); 616 if (offset == 0) 617 snprintf(SNPARGS(proto, len), ":%d %s:%d", 618 ntohs(udp->uh_sport), 619 inet_ntoa(ip->ip_dst), 620 ntohs(udp->uh_dport)); 621 else 622 snprintf(SNPARGS(proto, len), " %s", 623 inet_ntoa(ip->ip_dst)); 624 break; 625 626 case IPPROTO_ICMP: 627 if (offset == 0) 628 len = snprintf(SNPARGS(proto, 0), 629 "ICMP:%u.%u ", 630 icmp->icmp_type, icmp->icmp_code); 631 else 632 len = snprintf(SNPARGS(proto, 0), "ICMP "); 633 len += snprintf(SNPARGS(proto, len), "%s", 634 inet_ntoa(ip->ip_src)); 635 snprintf(SNPARGS(proto, len), " %s", 636 inet_ntoa(ip->ip_dst)); 637 break; 638 639 default: 640 len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, 641 inet_ntoa(ip->ip_src)); 642 snprintf(SNPARGS(proto, len), " %s", 643 inet_ntoa(ip->ip_dst)); 644 break; 645 } 646 647 if (ip_off & (IP_MF | IP_OFFMASK)) 648 snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", 649 ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), 650 offset << 3, 651 (ip_off & IP_MF) ? "+" : ""); 652 } 653 if (oif || m->m_pkthdr.rcvif) 654 log(LOG_SECURITY | LOG_INFO, 655 "ipfw: %d %s %s %s via %s%s\n", 656 f ? f->rulenum : -1, 657 action, proto, oif ? "out" : "in", 658 oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 659 fragment); 660 else 661 log(LOG_SECURITY | LOG_INFO, 662 "ipfw: %d %s %s [no if info]%s\n", 663 f ? f->rulenum : -1, 664 action, proto, fragment); 665 if (limit_reached) 666 log(LOG_SECURITY | LOG_NOTICE, 667 "ipfw: limit %d reached on entry %d\n", 668 limit_reached, f ? f->rulenum : -1); 669} 670 671/* 672 * IMPORTANT: the hash function for dynamic rules must be commutative 673 * in source and destination (ip,port), because rules are bidirectional 674 * and we want to find both in the same bucket. 675 */ 676static __inline int 677hash_packet(struct ipfw_flow_id *id) 678{ 679 u_int32_t i; 680 681 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 682 i &= (curr_dyn_buckets - 1); 683 return i; 684} 685 686/** 687 * unlink a dynamic rule from a chain. prev is a pointer to 688 * the previous one, q is a pointer to the rule to delete, 689 * head is a pointer to the head of the queue. 690 * Modifies q and potentially also head. 691 */ 692#define UNLINK_DYN_RULE(prev, head, q) { \ 693 ipfw_dyn_rule *old_q = q; \ 694 \ 695 /* remove a refcount to the parent */ \ 696 if (q->dyn_type == O_LIMIT) \ 697 q->parent->count--; \ 698 DEB(printf("ipfw: unlink entry 0x%08x %d -> 0x%08x %d, %d left\n",\ 699 (q->id.src_ip), (q->id.src_port), \ 700 (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ 701 if (prev != NULL) \ 702 prev->next = q = q->next; \ 703 else \ 704 head = q = q->next; \ 705 dyn_count--; \ 706 free(old_q, M_IPFW); } 707 708#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 709 710/** 711 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 712 * 713 * If keep_me == NULL, rules are deleted even if not expired, 714 * otherwise only expired rules are removed. 715 * 716 * The value of the second parameter is also used to point to identify 717 * a rule we absolutely do not want to remove (e.g. because we are 718 * holding a reference to it -- this is the case with O_LIMIT_PARENT 719 * rules). The pointer is only used for comparison, so any non-null 720 * value will do. 721 */ 722static void 723remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 724{ 725 static u_int32_t last_remove = 0; 726 727#define FORCE (keep_me == NULL) 728 729 ipfw_dyn_rule *prev, *q; 730 int i, pass = 0, max_pass = 0; 731 732 IPFW_DYN_LOCK_ASSERT(); 733 734 if (ipfw_dyn_v == NULL || dyn_count == 0) 735 return; 736 /* do not expire more than once per second, it is useless */ 737 if (!FORCE && last_remove == time_second) 738 return; 739 last_remove = time_second; 740 741 /* 742 * because O_LIMIT refer to parent rules, during the first pass only 743 * remove child and mark any pending LIMIT_PARENT, and remove 744 * them in a second pass. 745 */ 746next_pass: 747 for (i = 0 ; i < curr_dyn_buckets ; i++) { 748 for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { 749 /* 750 * Logic can become complex here, so we split tests. 751 */ 752 if (q == keep_me) 753 goto next; 754 if (rule != NULL && rule != q->rule) 755 goto next; /* not the one we are looking for */ 756 if (q->dyn_type == O_LIMIT_PARENT) { 757 /* 758 * handle parent in the second pass, 759 * record we need one. 760 */ 761 max_pass = 1; 762 if (pass == 0) 763 goto next; 764 if (FORCE && q->count != 0 ) { 765 /* XXX should not happen! */ 766 printf("ipfw: OUCH! cannot remove rule," 767 " count %d\n", q->count); 768 } 769 } else { 770 if (!FORCE && 771 !TIME_LEQ( q->expire, time_second )) 772 goto next; 773 } 774 if (q->dyn_type != O_LIMIT_PARENT || !q->count) { 775 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 776 continue; 777 } 778next: 779 prev=q; 780 q=q->next; 781 } 782 } 783 if (pass++ < max_pass) 784 goto next_pass; 785} 786 787 788/** 789 * lookup a dynamic rule. 790 */ 791static ipfw_dyn_rule * 792lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction, 793 struct tcphdr *tcp) 794{ 795 /* 796 * stateful ipfw extensions. 797 * Lookup into dynamic session queue 798 */ 799#define MATCH_REVERSE 0 800#define MATCH_FORWARD 1 801#define MATCH_NONE 2 802#define MATCH_UNKNOWN 3 803 int i, dir = MATCH_NONE; 804 ipfw_dyn_rule *prev, *q=NULL; 805 806 IPFW_DYN_LOCK_ASSERT(); 807 808 if (ipfw_dyn_v == NULL) 809 goto done; /* not found */ 810 i = hash_packet( pkt ); 811 for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { 812 if (q->dyn_type == O_LIMIT_PARENT && q->count) 813 goto next; 814 if (TIME_LEQ( q->expire, time_second)) { /* expire entry */ 815 UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); 816 continue; 817 } 818 if (pkt->proto == q->id.proto && 819 q->dyn_type != O_LIMIT_PARENT) { 820 if (pkt->src_ip == q->id.src_ip && 821 pkt->dst_ip == q->id.dst_ip && 822 pkt->src_port == q->id.src_port && 823 pkt->dst_port == q->id.dst_port ) { 824 dir = MATCH_FORWARD; 825 break; 826 } 827 if (pkt->src_ip == q->id.dst_ip && 828 pkt->dst_ip == q->id.src_ip && 829 pkt->src_port == q->id.dst_port && 830 pkt->dst_port == q->id.src_port ) { 831 dir = MATCH_REVERSE; 832 break; 833 } 834 } 835next: 836 prev = q; 837 q = q->next; 838 } 839 if (q == NULL) 840 goto done; /* q = NULL, not found */ 841 842 if ( prev != NULL) { /* found and not in front */ 843 prev->next = q->next; 844 q->next = ipfw_dyn_v[i]; 845 ipfw_dyn_v[i] = q; 846 } 847 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 848 u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); 849 850#define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 851#define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 852 q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); 853 switch (q->state) { 854 case TH_SYN: /* opening */ 855 q->expire = time_second + dyn_syn_lifetime; 856 break; 857 858 case BOTH_SYN: /* move to established */ 859 case BOTH_SYN | TH_FIN : /* one side tries to close */ 860 case BOTH_SYN | (TH_FIN << 8) : 861 if (tcp) { 862#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 863 u_int32_t ack = ntohl(tcp->th_ack); 864 if (dir == MATCH_FORWARD) { 865 if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) 866 q->ack_fwd = ack; 867 else { /* ignore out-of-sequence */ 868 break; 869 } 870 } else { 871 if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) 872 q->ack_rev = ack; 873 else { /* ignore out-of-sequence */ 874 break; 875 } 876 } 877 } 878 q->expire = time_second + dyn_ack_lifetime; 879 break; 880 881 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 882 if (dyn_fin_lifetime >= dyn_keepalive_period) 883 dyn_fin_lifetime = dyn_keepalive_period - 1; 884 q->expire = time_second + dyn_fin_lifetime; 885 break; 886 887 default: 888#if 0 889 /* 890 * reset or some invalid combination, but can also 891 * occur if we use keep-state the wrong way. 892 */ 893 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 894 printf("invalid state: 0x%x\n", q->state); 895#endif 896 if (dyn_rst_lifetime >= dyn_keepalive_period) 897 dyn_rst_lifetime = dyn_keepalive_period - 1; 898 q->expire = time_second + dyn_rst_lifetime; 899 break; 900 } 901 } else if (pkt->proto == IPPROTO_UDP) { 902 q->expire = time_second + dyn_udp_lifetime; 903 } else { 904 /* other protocols */ 905 q->expire = time_second + dyn_short_lifetime; 906 } 907done: 908 if (match_direction) 909 *match_direction = dir; 910 return q; 911} 912 913static ipfw_dyn_rule * 914lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 915 struct tcphdr *tcp) 916{ 917 ipfw_dyn_rule *q; 918 919 IPFW_DYN_LOCK(); 920 q = lookup_dyn_rule_locked(pkt, match_direction, tcp); 921 if (q == NULL) 922 IPFW_DYN_UNLOCK(); 923 /* NB: return table locked when q is not NULL */ 924 return q; 925} 926 927static void 928realloc_dynamic_table(void) 929{ 930 IPFW_DYN_LOCK_ASSERT(); 931 932 /* 933 * Try reallocation, make sure we have a power of 2 and do 934 * not allow more than 64k entries. In case of overflow, 935 * default to 1024. 936 */ 937 938 if (dyn_buckets > 65536) 939 dyn_buckets = 1024; 940 if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ 941 dyn_buckets = curr_dyn_buckets; /* reset */ 942 return; 943 } 944 curr_dyn_buckets = dyn_buckets; 945 if (ipfw_dyn_v != NULL) 946 free(ipfw_dyn_v, M_IPFW); 947 for (;;) { 948 ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 949 M_IPFW, M_NOWAIT | M_ZERO); 950 if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) 951 break; 952 curr_dyn_buckets /= 2; 953 } 954} 955 956/** 957 * Install state of type 'type' for a dynamic session. 958 * The hash table contains two type of rules: 959 * - regular rules (O_KEEP_STATE) 960 * - rules for sessions with limited number of sess per user 961 * (O_LIMIT). When they are created, the parent is 962 * increased by 1, and decreased on delete. In this case, 963 * the third parameter is the parent rule and not the chain. 964 * - "parent" rules for the above (O_LIMIT_PARENT). 965 */ 966static ipfw_dyn_rule * 967add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 968{ 969 ipfw_dyn_rule *r; 970 int i; 971 972 IPFW_DYN_LOCK_ASSERT(); 973 974 if (ipfw_dyn_v == NULL || 975 (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { 976 realloc_dynamic_table(); 977 if (ipfw_dyn_v == NULL) 978 return NULL; /* failed ! */ 979 } 980 i = hash_packet(id); 981 982 r = malloc(sizeof *r, M_IPFW, M_NOWAIT | M_ZERO); 983 if (r == NULL) { 984 printf ("ipfw: sorry cannot allocate state\n"); 985 return NULL; 986 } 987 988 /* increase refcount on parent, and set pointer */ 989 if (dyn_type == O_LIMIT) { 990 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 991 if ( parent->dyn_type != O_LIMIT_PARENT) 992 panic("invalid parent"); 993 parent->count++; 994 r->parent = parent; 995 rule = parent->rule; 996 } 997 998 r->id = *id; 999 r->expire = time_second + dyn_syn_lifetime; 1000 r->rule = rule; 1001 r->dyn_type = dyn_type; 1002 r->pcnt = r->bcnt = 0; 1003 r->count = 0; 1004 1005 r->bucket = i; 1006 r->next = ipfw_dyn_v[i]; 1007 ipfw_dyn_v[i] = r; 1008 dyn_count++; 1009 DEB(printf("ipfw: add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", 1010 dyn_type, 1011 (r->id.src_ip), (r->id.src_port), 1012 (r->id.dst_ip), (r->id.dst_port), 1013 dyn_count ); ) 1014 return r; 1015} 1016 1017/** 1018 * lookup dynamic parent rule using pkt and rule as search keys. 1019 * If the lookup fails, then install one. 1020 */ 1021static ipfw_dyn_rule * 1022lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 1023{ 1024 ipfw_dyn_rule *q; 1025 int i; 1026 1027 IPFW_DYN_LOCK_ASSERT(); 1028 1029 if (ipfw_dyn_v) { 1030 i = hash_packet( pkt ); 1031 for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) 1032 if (q->dyn_type == O_LIMIT_PARENT && 1033 rule== q->rule && 1034 pkt->proto == q->id.proto && 1035 pkt->src_ip == q->id.src_ip && 1036 pkt->dst_ip == q->id.dst_ip && 1037 pkt->src_port == q->id.src_port && 1038 pkt->dst_port == q->id.dst_port) { 1039 q->expire = time_second + dyn_short_lifetime; 1040 DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);) 1041 return q; 1042 } 1043 } 1044 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 1045} 1046 1047/** 1048 * Install dynamic state for rule type cmd->o.opcode 1049 * 1050 * Returns 1 (failure) if state is not installed because of errors or because 1051 * session limitations are enforced. 1052 */ 1053static int 1054install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 1055 struct ip_fw_args *args) 1056{ 1057 static int last_log; 1058 1059 ipfw_dyn_rule *q; 1060 1061 DEB(printf("ipfw: install state type %d 0x%08x %u -> 0x%08x %u\n", 1062 cmd->o.opcode, 1063 (args->f_id.src_ip), (args->f_id.src_port), 1064 (args->f_id.dst_ip), (args->f_id.dst_port) );) 1065 1066 IPFW_DYN_LOCK(); 1067 1068 q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL); 1069 1070 if (q != NULL) { /* should never occur */ 1071 if (last_log != time_second) { 1072 last_log = time_second; 1073 printf("ipfw: install_state: entry already present, done\n"); 1074 } 1075 IPFW_DYN_UNLOCK(); 1076 return 0; 1077 } 1078 1079 if (dyn_count >= dyn_max) 1080 /* 1081 * Run out of slots, try to remove any expired rule. 1082 */ 1083 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 1084 1085 if (dyn_count >= dyn_max) { 1086 if (last_log != time_second) { 1087 last_log = time_second; 1088 printf("ipfw: install_state: Too many dynamic rules\n"); 1089 } 1090 IPFW_DYN_UNLOCK(); 1091 return 1; /* cannot install, notify caller */ 1092 } 1093 1094 switch (cmd->o.opcode) { 1095 case O_KEEP_STATE: /* bidir rule */ 1096 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 1097 break; 1098 1099 case O_LIMIT: /* limit number of sessions */ 1100 { 1101 u_int16_t limit_mask = cmd->limit_mask; 1102 struct ipfw_flow_id id; 1103 ipfw_dyn_rule *parent; 1104 1105 DEB(printf("ipfw: installing dyn-limit rule %d\n", 1106 cmd->conn_limit);) 1107 1108 id.dst_ip = id.src_ip = 0; 1109 id.dst_port = id.src_port = 0; 1110 id.proto = args->f_id.proto; 1111 1112 if (limit_mask & DYN_SRC_ADDR) 1113 id.src_ip = args->f_id.src_ip; 1114 if (limit_mask & DYN_DST_ADDR) 1115 id.dst_ip = args->f_id.dst_ip; 1116 if (limit_mask & DYN_SRC_PORT) 1117 id.src_port = args->f_id.src_port; 1118 if (limit_mask & DYN_DST_PORT) 1119 id.dst_port = args->f_id.dst_port; 1120 parent = lookup_dyn_parent(&id, rule); 1121 if (parent == NULL) { 1122 printf("ipfw: add parent failed\n"); 1123 return 1; 1124 } 1125 if (parent->count >= cmd->conn_limit) { 1126 /* 1127 * See if we can remove some expired rule. 1128 */ 1129 remove_dyn_rule(rule, parent); 1130 if (parent->count >= cmd->conn_limit) { 1131 if (fw_verbose && last_log != time_second) { 1132 last_log = time_second; 1133 log(LOG_SECURITY | LOG_DEBUG, 1134 "drop session, too many entries\n"); 1135 } 1136 IPFW_DYN_UNLOCK(); 1137 return 1; 1138 } 1139 } 1140 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 1141 } 1142 break; 1143 default: 1144 printf("ipfw: unknown dynamic rule type %u\n", cmd->o.opcode); 1145 IPFW_DYN_UNLOCK(); 1146 return 1; 1147 } 1148 lookup_dyn_rule_locked(&args->f_id, NULL, NULL); /* XXX just set lifetime */ 1149 IPFW_DYN_UNLOCK(); 1150 return 0; 1151} 1152 1153/* 1154 * Transmit a TCP packet, containing either a RST or a keepalive. 1155 * When flags & TH_RST, we are sending a RST packet, because of a 1156 * "reset" action matched the packet. 1157 * Otherwise we are sending a keepalive, and flags & TH_ 1158 */ 1159static void 1160send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) 1161{ 1162 struct mbuf *m; 1163 struct ip *ip; 1164 struct tcphdr *tcp; 1165 1166 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1167 if (m == 0) 1168 return; 1169 m->m_pkthdr.rcvif = (struct ifnet *)0; 1170 m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); 1171 m->m_data += max_linkhdr; 1172 1173 ip = mtod(m, struct ip *); 1174 bzero(ip, m->m_len); 1175 tcp = (struct tcphdr *)(ip + 1); /* no IP options */ 1176 ip->ip_p = IPPROTO_TCP; 1177 tcp->th_off = 5; 1178 /* 1179 * Assume we are sending a RST (or a keepalive in the reverse 1180 * direction), swap src and destination addresses and ports. 1181 */ 1182 ip->ip_src.s_addr = htonl(id->dst_ip); 1183 ip->ip_dst.s_addr = htonl(id->src_ip); 1184 tcp->th_sport = htons(id->dst_port); 1185 tcp->th_dport = htons(id->src_port); 1186 if (flags & TH_RST) { /* we are sending a RST */ 1187 if (flags & TH_ACK) { 1188 tcp->th_seq = htonl(ack); 1189 tcp->th_ack = htonl(0); 1190 tcp->th_flags = TH_RST; 1191 } else { 1192 if (flags & TH_SYN) 1193 seq++; 1194 tcp->th_seq = htonl(0); 1195 tcp->th_ack = htonl(seq); 1196 tcp->th_flags = TH_RST | TH_ACK; 1197 } 1198 } else { 1199 /* 1200 * We are sending a keepalive. flags & TH_SYN determines 1201 * the direction, forward if set, reverse if clear. 1202 * NOTE: seq and ack are always assumed to be correct 1203 * as set by the caller. This may be confusing... 1204 */ 1205 if (flags & TH_SYN) { 1206 /* 1207 * we have to rewrite the correct addresses! 1208 */ 1209 ip->ip_dst.s_addr = htonl(id->dst_ip); 1210 ip->ip_src.s_addr = htonl(id->src_ip); 1211 tcp->th_dport = htons(id->dst_port); 1212 tcp->th_sport = htons(id->src_port); 1213 } 1214 tcp->th_seq = htonl(seq); 1215 tcp->th_ack = htonl(ack); 1216 tcp->th_flags = TH_ACK; 1217 } 1218 /* 1219 * set ip_len to the payload size so we can compute 1220 * the tcp checksum on the pseudoheader 1221 * XXX check this, could save a couple of words ? 1222 */ 1223 ip->ip_len = htons(sizeof(struct tcphdr)); 1224 tcp->th_sum = in_cksum(m, m->m_pkthdr.len); 1225 /* 1226 * now fill fields left out earlier 1227 */ 1228 ip->ip_ttl = ip_defttl; 1229 ip->ip_len = m->m_pkthdr.len; 1230 m->m_flags |= M_SKIP_FIREWALL; 1231 ip_output(m, NULL, NULL, 0, NULL, NULL); 1232} 1233 1234/* 1235 * sends a reject message, consuming the mbuf passed as an argument. 1236 */ 1237static void 1238send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) 1239{ 1240 1241 if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ 1242 /* We need the IP header in host order for icmp_error(). */ 1243 if (args->eh != NULL) { 1244 struct ip *ip = mtod(args->m, struct ip *); 1245 ip->ip_len = ntohs(ip->ip_len); 1246 ip->ip_off = ntohs(ip->ip_off); 1247 } 1248 icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); 1249 } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { 1250 struct tcphdr *const tcp = 1251 L3HDR(struct tcphdr, mtod(args->m, struct ip *)); 1252 if ( (tcp->th_flags & TH_RST) == 0) 1253 send_pkt(&(args->f_id), ntohl(tcp->th_seq), 1254 ntohl(tcp->th_ack), 1255 tcp->th_flags | TH_RST); 1256 m_freem(args->m); 1257 } else 1258 m_freem(args->m); 1259 args->m = NULL; 1260} 1261 1262/** 1263 * 1264 * Given an ip_fw *, lookup_next_rule will return a pointer 1265 * to the next rule, which can be either the jump 1266 * target (for skipto instructions) or the next one in the list (in 1267 * all other cases including a missing jump target). 1268 * The result is also written in the "next_rule" field of the rule. 1269 * Backward jumps are not allowed, so start looking from the next 1270 * rule... 1271 * 1272 * This never returns NULL -- in case we do not have an exact match, 1273 * the next rule is returned. When the ruleset is changed, 1274 * pointers are flushed so we are always correct. 1275 */ 1276 1277static struct ip_fw * 1278lookup_next_rule(struct ip_fw *me) 1279{ 1280 struct ip_fw *rule = NULL; 1281 ipfw_insn *cmd; 1282 1283 /* look for action, in case it is a skipto */ 1284 cmd = ACTION_PTR(me); 1285 if (cmd->opcode == O_LOG) 1286 cmd += F_LEN(cmd); 1287 if ( cmd->opcode == O_SKIPTO ) 1288 for (rule = me->next; rule ; rule = rule->next) 1289 if (rule->rulenum >= cmd->arg1) 1290 break; 1291 if (rule == NULL) /* failure or not a skipto */ 1292 rule = me->next; 1293 me->next_rule = rule; 1294 return rule; 1295} 1296 1297static int 1298check_uidgid(ipfw_insn_u32 *insn, 1299 int proto, struct ifnet *oif, 1300 struct in_addr dst_ip, u_int16_t dst_port, 1301 struct in_addr src_ip, u_int16_t src_port) 1302{ 1303 struct inpcbinfo *pi; 1304 int wildcard; 1305 struct inpcb *pcb; 1306 int match; 1307 1308 if (proto == IPPROTO_TCP) { 1309 wildcard = 0; 1310 pi = &tcbinfo; 1311 } else if (proto == IPPROTO_UDP) { 1312 wildcard = 1; 1313 pi = &udbinfo; 1314 } else 1315 return 0; 1316 1317 match = 0; 1318 1319 INP_INFO_RLOCK(pi); /* XXX LOR with IPFW */ 1320 pcb = (oif) ? 1321 in_pcblookup_hash(pi, 1322 dst_ip, htons(dst_port), 1323 src_ip, htons(src_port), 1324 wildcard, oif) : 1325 in_pcblookup_hash(pi, 1326 src_ip, htons(src_port), 1327 dst_ip, htons(dst_port), 1328 wildcard, NULL); 1329 if (pcb != NULL) { 1330 INP_LOCK(pcb); 1331 if (pcb->inp_socket != NULL) { 1332#if __FreeBSD_version < 500034 1333#define socheckuid(a,b) ((a)->so_cred->cr_uid != (b)) 1334#endif 1335 if (insn->o.opcode == O_UID) { 1336 match = !socheckuid(pcb->inp_socket, 1337 (uid_t)insn->d[0]); 1338 } else { 1339 match = groupmember((uid_t)insn->d[0], 1340 pcb->inp_socket->so_cred); 1341 } 1342 } 1343 INP_UNLOCK(pcb); 1344 } 1345 INP_INFO_RUNLOCK(pi); 1346 1347 return match; 1348} 1349 1350/* 1351 * The main check routine for the firewall. 1352 * 1353 * All arguments are in args so we can modify them and return them 1354 * back to the caller. 1355 * 1356 * Parameters: 1357 * 1358 * args->m (in/out) The packet; we set to NULL when/if we nuke it. 1359 * Starts with the IP header. 1360 * args->eh (in) Mac header if present, or NULL for layer3 packet. 1361 * args->oif Outgoing interface, or NULL if packet is incoming. 1362 * The incoming interface is in the mbuf. (in) 1363 * args->divert_rule (in/out) 1364 * Skip up to the first rule past this rule number; 1365 * upon return, non-zero port number for divert or tee. 1366 * 1367 * args->rule Pointer to the last matching rule (in/out) 1368 * args->next_hop Socket we are forwarding to (out). 1369 * args->f_id Addresses grabbed from the packet (out) 1370 * 1371 * Return value: 1372 * 1373 * IP_FW_PORT_DENY_FLAG the packet must be dropped. 1374 * 0 The packet is to be accepted and routed normally OR 1375 * the packet was denied/rejected and has been dropped; 1376 * in the latter case, *m is equal to NULL upon return. 1377 * port Divert the packet to port, with these caveats: 1378 * 1379 * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead 1380 * of diverting it (ie, 'ipfw tee'). 1381 * 1382 * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower 1383 * 16 bits as a dummynet pipe number instead of diverting 1384 */ 1385 1386static int 1387ipfw_chk(struct ip_fw_args *args) 1388{ 1389 /* 1390 * Local variables hold state during the processing of a packet. 1391 * 1392 * IMPORTANT NOTE: to speed up the processing of rules, there 1393 * are some assumption on the values of the variables, which 1394 * are documented here. Should you change them, please check 1395 * the implementation of the various instructions to make sure 1396 * that they still work. 1397 * 1398 * args->eh The MAC header. It is non-null for a layer2 1399 * packet, it is NULL for a layer-3 packet. 1400 * 1401 * m | args->m Pointer to the mbuf, as received from the caller. 1402 * It may change if ipfw_chk() does an m_pullup, or if it 1403 * consumes the packet because it calls send_reject(). 1404 * XXX This has to change, so that ipfw_chk() never modifies 1405 * or consumes the buffer. 1406 * ip is simply an alias of the value of m, and it is kept 1407 * in sync with it (the packet is supposed to start with 1408 * the ip header). 1409 */ 1410 struct mbuf *m = args->m; 1411 struct ip *ip = mtod(m, struct ip *); 1412 1413 /* 1414 * oif | args->oif If NULL, ipfw_chk has been called on the 1415 * inbound path (ether_input, bdg_forward, ip_input). 1416 * If non-NULL, ipfw_chk has been called on the outbound path 1417 * (ether_output, ip_output). 1418 */ 1419 struct ifnet *oif = args->oif; 1420 1421 struct ip_fw *f = NULL; /* matching rule */ 1422 int retval = 0; 1423 1424 /* 1425 * hlen The length of the IPv4 header. 1426 * hlen >0 means we have an IPv4 packet. 1427 */ 1428 u_int hlen = 0; /* hlen >0 means we have an IP pkt */ 1429 1430 /* 1431 * offset The offset of a fragment. offset != 0 means that 1432 * we have a fragment at this offset of an IPv4 packet. 1433 * offset == 0 means that (if this is an IPv4 packet) 1434 * this is the first or only fragment. 1435 */ 1436 u_short offset = 0; 1437 1438 /* 1439 * Local copies of addresses. They are only valid if we have 1440 * an IP packet. 1441 * 1442 * proto The protocol. Set to 0 for non-ip packets, 1443 * or to the protocol read from the packet otherwise. 1444 * proto != 0 means that we have an IPv4 packet. 1445 * 1446 * src_port, dst_port port numbers, in HOST format. Only 1447 * valid for TCP and UDP packets. 1448 * 1449 * src_ip, dst_ip ip addresses, in NETWORK format. 1450 * Only valid for IPv4 packets. 1451 */ 1452 u_int8_t proto; 1453 u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ 1454 struct in_addr src_ip, dst_ip; /* NOTE: network format */ 1455 u_int16_t ip_len=0; 1456 int pktlen; 1457 int dyn_dir = MATCH_UNKNOWN; 1458 ipfw_dyn_rule *q = NULL; 1459 struct ip_fw_chain *chain = &layer3_chain; 1460 1461 if (m->m_flags & M_SKIP_FIREWALL) 1462 return 0; /* accept */ 1463 /* 1464 * dyn_dir = MATCH_UNKNOWN when rules unchecked, 1465 * MATCH_NONE when checked and not matched (q = NULL), 1466 * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) 1467 */ 1468 1469 pktlen = m->m_pkthdr.len; 1470 if (args->eh == NULL || /* layer 3 packet */ 1471 ( m->m_pkthdr.len >= sizeof(struct ip) && 1472 ntohs(args->eh->ether_type) == ETHERTYPE_IP)) 1473 hlen = ip->ip_hl << 2; 1474 1475 /* 1476 * Collect parameters into local variables for faster matching. 1477 */ 1478 if (hlen == 0) { /* do not grab addresses for non-ip pkts */ 1479 proto = args->f_id.proto = 0; /* mark f_id invalid */ 1480 goto after_ip_checks; 1481 } 1482 1483 proto = args->f_id.proto = ip->ip_p; 1484 src_ip = ip->ip_src; 1485 dst_ip = ip->ip_dst; 1486 if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 1487 offset = ntohs(ip->ip_off) & IP_OFFMASK; 1488 ip_len = ntohs(ip->ip_len); 1489 } else { 1490 offset = ip->ip_off & IP_OFFMASK; 1491 ip_len = ip->ip_len; 1492 } 1493 pktlen = ip_len < pktlen ? ip_len : pktlen; 1494 1495#define PULLUP_TO(len) \ 1496 do { \ 1497 if ((m)->m_len < (len)) { \ 1498 args->m = m = m_pullup(m, (len)); \ 1499 if (m == 0) \ 1500 goto pullup_failed; \ 1501 ip = mtod(m, struct ip *); \ 1502 } \ 1503 } while (0) 1504 1505 if (offset == 0) { 1506 switch (proto) { 1507 case IPPROTO_TCP: 1508 { 1509 struct tcphdr *tcp; 1510 1511 PULLUP_TO(hlen + sizeof(struct tcphdr)); 1512 tcp = L3HDR(struct tcphdr, ip); 1513 dst_port = tcp->th_dport; 1514 src_port = tcp->th_sport; 1515 args->f_id.flags = tcp->th_flags; 1516 } 1517 break; 1518 1519 case IPPROTO_UDP: 1520 { 1521 struct udphdr *udp; 1522 1523 PULLUP_TO(hlen + sizeof(struct udphdr)); 1524 udp = L3HDR(struct udphdr, ip); 1525 dst_port = udp->uh_dport; 1526 src_port = udp->uh_sport; 1527 } 1528 break; 1529 1530 case IPPROTO_ICMP: 1531 PULLUP_TO(hlen + 4); /* type, code and checksum. */ 1532 args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; 1533 break; 1534 1535 default: 1536 break; 1537 } 1538#undef PULLUP_TO 1539 } 1540 1541 args->f_id.src_ip = ntohl(src_ip.s_addr); 1542 args->f_id.dst_ip = ntohl(dst_ip.s_addr); 1543 args->f_id.src_port = src_port = ntohs(src_port); 1544 args->f_id.dst_port = dst_port = ntohs(dst_port); 1545 1546after_ip_checks: 1547 IPFW_LOCK(chain); /* XXX expensive? can we run lock free? */ 1548 if (args->rule) { 1549 /* 1550 * Packet has already been tagged. Look for the next rule 1551 * to restart processing. 1552 * 1553 * If fw_one_pass != 0 then just accept it. 1554 * XXX should not happen here, but optimized out in 1555 * the caller. 1556 */ 1557 if (fw_one_pass) { 1558 IPFW_UNLOCK(chain); /* XXX optimize */ 1559 return 0; 1560 } 1561 1562 f = args->rule->next_rule; 1563 if (f == NULL) 1564 f = lookup_next_rule(args->rule); 1565 } else { 1566 /* 1567 * Find the starting rule. It can be either the first 1568 * one, or the one after divert_rule if asked so. 1569 */ 1570 int skipto = args->divert_rule; 1571 1572 f = chain->rules; 1573 if (args->eh == NULL && skipto != 0) { 1574 if (skipto >= IPFW_DEFAULT_RULE) { 1575 IPFW_UNLOCK(chain); 1576 return(IP_FW_PORT_DENY_FLAG); /* invalid */ 1577 } 1578 while (f && f->rulenum <= skipto) 1579 f = f->next; 1580 if (f == NULL) { /* drop packet */ 1581 IPFW_UNLOCK(chain); 1582 return(IP_FW_PORT_DENY_FLAG); 1583 } 1584 } 1585 } 1586 args->divert_rule = 0; /* reset to avoid confusion later */ 1587 1588 /* 1589 * Now scan the rules, and parse microinstructions for each rule. 1590 */ 1591 for (; f; f = f->next) { 1592 int l, cmdlen; 1593 ipfw_insn *cmd; 1594 int skip_or; /* skip rest of OR block */ 1595 1596again: 1597 if (set_disable & (1 << f->set) ) 1598 continue; 1599 1600 skip_or = 0; 1601 for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; 1602 l -= cmdlen, cmd += cmdlen) { 1603 int match; 1604 1605 /* 1606 * check_body is a jump target used when we find a 1607 * CHECK_STATE, and need to jump to the body of 1608 * the target rule. 1609 */ 1610 1611check_body: 1612 cmdlen = F_LEN(cmd); 1613 /* 1614 * An OR block (insn_1 || .. || insn_n) has the 1615 * F_OR bit set in all but the last instruction. 1616 * The first match will set "skip_or", and cause 1617 * the following instructions to be skipped until 1618 * past the one with the F_OR bit clear. 1619 */ 1620 if (skip_or) { /* skip this instruction */ 1621 if ((cmd->len & F_OR) == 0) 1622 skip_or = 0; /* next one is good */ 1623 continue; 1624 } 1625 match = 0; /* set to 1 if we succeed */ 1626 1627 switch (cmd->opcode) { 1628 /* 1629 * The first set of opcodes compares the packet's 1630 * fields with some pattern, setting 'match' if a 1631 * match is found. At the end of the loop there is 1632 * logic to deal with F_NOT and F_OR flags associated 1633 * with the opcode. 1634 */ 1635 case O_NOP: 1636 match = 1; 1637 break; 1638 1639 case O_FORWARD_MAC: 1640 printf("ipfw: opcode %d unimplemented\n", 1641 cmd->opcode); 1642 break; 1643 1644 case O_GID: 1645 case O_UID: 1646 /* 1647 * We only check offset == 0 && proto != 0, 1648 * as this ensures that we have an IPv4 1649 * packet with the ports info. 1650 */ 1651 if (offset!=0) 1652 break; 1653 if (proto == IPPROTO_TCP || 1654 proto == IPPROTO_UDP) 1655 match = check_uidgid( 1656 (ipfw_insn_u32 *)cmd, 1657 proto, oif, 1658 dst_ip, dst_port, 1659 src_ip, src_port); 1660 break; 1661 1662 case O_RECV: 1663 match = iface_match(m->m_pkthdr.rcvif, 1664 (ipfw_insn_if *)cmd); 1665 break; 1666 1667 case O_XMIT: 1668 match = iface_match(oif, (ipfw_insn_if *)cmd); 1669 break; 1670 1671 case O_VIA: 1672 match = iface_match(oif ? oif : 1673 m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); 1674 break; 1675 1676 case O_MACADDR2: 1677 if (args->eh != NULL) { /* have MAC header */ 1678 u_int32_t *want = (u_int32_t *) 1679 ((ipfw_insn_mac *)cmd)->addr; 1680 u_int32_t *mask = (u_int32_t *) 1681 ((ipfw_insn_mac *)cmd)->mask; 1682 u_int32_t *hdr = (u_int32_t *)args->eh; 1683 1684 match = 1685 ( want[0] == (hdr[0] & mask[0]) && 1686 want[1] == (hdr[1] & mask[1]) && 1687 want[2] == (hdr[2] & mask[2]) ); 1688 } 1689 break; 1690 1691 case O_MAC_TYPE: 1692 if (args->eh != NULL) { 1693 u_int16_t t = 1694 ntohs(args->eh->ether_type); 1695 u_int16_t *p = 1696 ((ipfw_insn_u16 *)cmd)->ports; 1697 int i; 1698 1699 for (i = cmdlen - 1; !match && i>0; 1700 i--, p += 2) 1701 match = (t>=p[0] && t<=p[1]); 1702 } 1703 break; 1704 1705 case O_FRAG: 1706 match = (hlen > 0 && offset != 0); 1707 break; 1708 1709 case O_IN: /* "out" is "not in" */ 1710 match = (oif == NULL); 1711 break; 1712 1713 case O_LAYER2: 1714 match = (args->eh != NULL); 1715 break; 1716 1717 case O_PROTO: 1718 /* 1719 * We do not allow an arg of 0 so the 1720 * check of "proto" only suffices. 1721 */ 1722 match = (proto == cmd->arg1); 1723 break; 1724 1725 case O_IP_SRC: 1726 match = (hlen > 0 && 1727 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1728 src_ip.s_addr); 1729 break; 1730 1731 case O_IP_SRC_MASK: 1732 case O_IP_DST_MASK: 1733 if (hlen > 0) { 1734 uint32_t a = 1735 (cmd->opcode == O_IP_DST_MASK) ? 1736 dst_ip.s_addr : src_ip.s_addr; 1737 uint32_t *p = ((ipfw_insn_u32 *)cmd)->d; 1738 int i = cmdlen-1; 1739 1740 for (; !match && i>0; i-= 2, p+= 2) 1741 match = (p[0] == (a & p[1])); 1742 } 1743 break; 1744 1745 case O_IP_SRC_ME: 1746 if (hlen > 0) { 1747 struct ifnet *tif; 1748 1749 INADDR_TO_IFP(src_ip, tif); 1750 match = (tif != NULL); 1751 } 1752 break; 1753 1754 case O_IP_DST_SET: 1755 case O_IP_SRC_SET: 1756 if (hlen > 0) { 1757 u_int32_t *d = (u_int32_t *)(cmd+1); 1758 u_int32_t addr = 1759 cmd->opcode == O_IP_DST_SET ? 1760 args->f_id.dst_ip : 1761 args->f_id.src_ip; 1762 1763 if (addr < d[0]) 1764 break; 1765 addr -= d[0]; /* subtract base */ 1766 match = (addr < cmd->arg1) && 1767 ( d[ 1 + (addr>>5)] & 1768 (1<<(addr & 0x1f)) ); 1769 } 1770 break; 1771 1772 case O_IP_DST: 1773 match = (hlen > 0 && 1774 ((ipfw_insn_ip *)cmd)->addr.s_addr == 1775 dst_ip.s_addr); 1776 break; 1777 1778 case O_IP_DST_ME: 1779 if (hlen > 0) { 1780 struct ifnet *tif; 1781 1782 INADDR_TO_IFP(dst_ip, tif); 1783 match = (tif != NULL); 1784 } 1785 break; 1786 1787 case O_IP_SRCPORT: 1788 case O_IP_DSTPORT: 1789 /* 1790 * offset == 0 && proto != 0 is enough 1791 * to guarantee that we have an IPv4 1792 * packet with port info. 1793 */ 1794 if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) 1795 && offset == 0) { 1796 u_int16_t x = 1797 (cmd->opcode == O_IP_SRCPORT) ? 1798 src_port : dst_port ; 1799 u_int16_t *p = 1800 ((ipfw_insn_u16 *)cmd)->ports; 1801 int i; 1802 1803 for (i = cmdlen - 1; !match && i>0; 1804 i--, p += 2) 1805 match = (x>=p[0] && x<=p[1]); 1806 } 1807 break; 1808 1809 case O_ICMPTYPE: 1810 match = (offset == 0 && proto==IPPROTO_ICMP && 1811 icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); 1812 break; 1813 1814 case O_IPOPT: 1815 match = (hlen > 0 && ipopts_match(ip, cmd) ); 1816 break; 1817 1818 case O_IPVER: 1819 match = (hlen > 0 && cmd->arg1 == ip->ip_v); 1820 break; 1821 1822 case O_IPID: 1823 case O_IPLEN: 1824 case O_IPTTL: 1825 if (hlen > 0) { /* only for IP packets */ 1826 uint16_t x; 1827 uint16_t *p; 1828 int i; 1829 1830 if (cmd->opcode == O_IPLEN) 1831 x = ip_len; 1832 else if (cmd->opcode == O_IPTTL) 1833 x = ip->ip_ttl; 1834 else /* must be IPID */ 1835 x = ntohs(ip->ip_id); 1836 if (cmdlen == 1) { 1837 match = (cmd->arg1 == x); 1838 break; 1839 } 1840 /* otherwise we have ranges */ 1841 p = ((ipfw_insn_u16 *)cmd)->ports; 1842 i = cmdlen - 1; 1843 for (; !match && i>0; i--, p += 2) 1844 match = (x >= p[0] && x <= p[1]); 1845 } 1846 break; 1847 1848 case O_IPPRECEDENCE: 1849 match = (hlen > 0 && 1850 (cmd->arg1 == (ip->ip_tos & 0xe0)) ); 1851 break; 1852 1853 case O_IPTOS: 1854 match = (hlen > 0 && 1855 flags_match(cmd, ip->ip_tos)); 1856 break; 1857 1858 case O_TCPFLAGS: 1859 match = (proto == IPPROTO_TCP && offset == 0 && 1860 flags_match(cmd, 1861 L3HDR(struct tcphdr,ip)->th_flags)); 1862 break; 1863 1864 case O_TCPOPTS: 1865 match = (proto == IPPROTO_TCP && offset == 0 && 1866 tcpopts_match(ip, cmd)); 1867 break; 1868 1869 case O_TCPSEQ: 1870 match = (proto == IPPROTO_TCP && offset == 0 && 1871 ((ipfw_insn_u32 *)cmd)->d[0] == 1872 L3HDR(struct tcphdr,ip)->th_seq); 1873 break; 1874 1875 case O_TCPACK: 1876 match = (proto == IPPROTO_TCP && offset == 0 && 1877 ((ipfw_insn_u32 *)cmd)->d[0] == 1878 L3HDR(struct tcphdr,ip)->th_ack); 1879 break; 1880 1881 case O_TCPWIN: 1882 match = (proto == IPPROTO_TCP && offset == 0 && 1883 cmd->arg1 == 1884 L3HDR(struct tcphdr,ip)->th_win); 1885 break; 1886 1887 case O_ESTAB: 1888 /* reject packets which have SYN only */ 1889 /* XXX should i also check for TH_ACK ? */ 1890 match = (proto == IPPROTO_TCP && offset == 0 && 1891 (L3HDR(struct tcphdr,ip)->th_flags & 1892 (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); 1893 break; 1894 1895 case O_LOG: 1896 if (fw_verbose) 1897 ipfw_log(f, hlen, args->eh, m, oif); 1898 match = 1; 1899 break; 1900 1901 case O_PROB: 1902 match = (random()<((ipfw_insn_u32 *)cmd)->d[0]); 1903 break; 1904 1905 case O_VERREVPATH: 1906 /* Outgoing packets automatically pass/match */ 1907 match = ((oif != NULL) || 1908 (m->m_pkthdr.rcvif == NULL) || 1909 verify_rev_path(src_ip, m->m_pkthdr.rcvif)); 1910 break; 1911 1912 case O_IPSEC: 1913#ifdef FAST_IPSEC 1914 match = (m_tag_find(m, 1915 PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL); 1916#endif 1917#ifdef IPSEC 1918 match = (ipsec_getnhist(m) != NULL); 1919#endif 1920 /* otherwise no match */ 1921 break; 1922 1923 /* 1924 * The second set of opcodes represents 'actions', 1925 * i.e. the terminal part of a rule once the packet 1926 * matches all previous patterns. 1927 * Typically there is only one action for each rule, 1928 * and the opcode is stored at the end of the rule 1929 * (but there are exceptions -- see below). 1930 * 1931 * In general, here we set retval and terminate the 1932 * outer loop (would be a 'break 3' in some language, 1933 * but we need to do a 'goto done'). 1934 * 1935 * Exceptions: 1936 * O_COUNT and O_SKIPTO actions: 1937 * instead of terminating, we jump to the next rule 1938 * ('goto next_rule', equivalent to a 'break 2'), 1939 * or to the SKIPTO target ('goto again' after 1940 * having set f, cmd and l), respectively. 1941 * 1942 * O_LIMIT and O_KEEP_STATE: these opcodes are 1943 * not real 'actions', and are stored right 1944 * before the 'action' part of the rule. 1945 * These opcodes try to install an entry in the 1946 * state tables; if successful, we continue with 1947 * the next opcode (match=1; break;), otherwise 1948 * the packet * must be dropped 1949 * ('goto done' after setting retval); 1950 * 1951 * O_PROBE_STATE and O_CHECK_STATE: these opcodes 1952 * cause a lookup of the state table, and a jump 1953 * to the 'action' part of the parent rule 1954 * ('goto check_body') if an entry is found, or 1955 * (CHECK_STATE only) a jump to the next rule if 1956 * the entry is not found ('goto next_rule'). 1957 * The result of the lookup is cached to make 1958 * further instances of these opcodes are 1959 * effectively NOPs. 1960 */ 1961 case O_LIMIT: 1962 case O_KEEP_STATE: 1963 if (install_state(f, 1964 (ipfw_insn_limit *)cmd, args)) { 1965 retval = IP_FW_PORT_DENY_FLAG; 1966 goto done; /* error/limit violation */ 1967 } 1968 match = 1; 1969 break; 1970 1971 case O_PROBE_STATE: 1972 case O_CHECK_STATE: 1973 /* 1974 * dynamic rules are checked at the first 1975 * keep-state or check-state occurrence, 1976 * with the result being stored in dyn_dir. 1977 * The compiler introduces a PROBE_STATE 1978 * instruction for us when we have a 1979 * KEEP_STATE (because PROBE_STATE needs 1980 * to be run first). 1981 */ 1982 if (dyn_dir == MATCH_UNKNOWN && 1983 (q = lookup_dyn_rule(&args->f_id, 1984 &dyn_dir, proto == IPPROTO_TCP ? 1985 L3HDR(struct tcphdr, ip) : NULL)) 1986 != NULL) { 1987 /* 1988 * Found dynamic entry, update stats 1989 * and jump to the 'action' part of 1990 * the parent rule. 1991 */ 1992 q->pcnt++; 1993 q->bcnt += pktlen; 1994 f = q->rule; 1995 cmd = ACTION_PTR(f); 1996 l = f->cmd_len - f->act_ofs; 1997 IPFW_DYN_UNLOCK(); 1998 goto check_body; 1999 } 2000 /* 2001 * Dynamic entry not found. If CHECK_STATE, 2002 * skip to next rule, if PROBE_STATE just 2003 * ignore and continue with next opcode. 2004 */ 2005 if (cmd->opcode == O_CHECK_STATE) 2006 goto next_rule; 2007 match = 1; 2008 break; 2009 2010 case O_ACCEPT: 2011 retval = 0; /* accept */ 2012 goto done; 2013 2014 case O_PIPE: 2015 case O_QUEUE: 2016 args->rule = f; /* report matching rule */ 2017 retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; 2018 goto done; 2019 2020 case O_DIVERT: 2021 case O_TEE: 2022 if (args->eh) /* not on layer 2 */ 2023 break; 2024 args->divert_rule = f->rulenum; 2025 retval = (cmd->opcode == O_DIVERT) ? 2026 cmd->arg1 : 2027 cmd->arg1 | IP_FW_PORT_TEE_FLAG; 2028 goto done; 2029 2030 case O_COUNT: 2031 case O_SKIPTO: 2032 f->pcnt++; /* update stats */ 2033 f->bcnt += pktlen; 2034 f->timestamp = time_second; 2035 if (cmd->opcode == O_COUNT) 2036 goto next_rule; 2037 /* handle skipto */ 2038 if (f->next_rule == NULL) 2039 lookup_next_rule(f); 2040 f = f->next_rule; 2041 goto again; 2042 2043 case O_REJECT: 2044 /* 2045 * Drop the packet and send a reject notice 2046 * if the packet is not ICMP (or is an ICMP 2047 * query), and it is not multicast/broadcast. 2048 */ 2049 if (hlen > 0 && 2050 (proto != IPPROTO_ICMP || 2051 is_icmp_query(ip)) && 2052 !(m->m_flags & (M_BCAST|M_MCAST)) && 2053 !IN_MULTICAST(dst_ip.s_addr)) { 2054 send_reject(args, cmd->arg1, 2055 offset,ip_len); 2056 m = args->m; 2057 } 2058 /* FALLTHROUGH */ 2059 case O_DENY: 2060 retval = IP_FW_PORT_DENY_FLAG; 2061 goto done; 2062 2063 case O_FORWARD_IP: 2064 if (args->eh) /* not valid on layer2 pkts */ 2065 break; 2066 if (!q || dyn_dir == MATCH_FORWARD) 2067 args->next_hop = 2068 &((ipfw_insn_sa *)cmd)->sa; 2069 retval = 0; 2070 goto done; 2071 2072 default: 2073 panic("-- unknown opcode %d\n", cmd->opcode); 2074 } /* end of switch() on opcodes */ 2075 2076 if (cmd->len & F_NOT) 2077 match = !match; 2078 2079 if (match) { 2080 if (cmd->len & F_OR) 2081 skip_or = 1; 2082 } else { 2083 if (!(cmd->len & F_OR)) /* not an OR block, */ 2084 break; /* try next rule */ 2085 } 2086 2087 } /* end of inner for, scan opcodes */ 2088 2089next_rule:; /* try next rule */ 2090 2091 } /* end of outer for, scan rules */ 2092 printf("ipfw: ouch!, skip past end of rules, denying packet\n"); 2093 IPFW_UNLOCK(chain); 2094 return(IP_FW_PORT_DENY_FLAG); 2095 2096done: 2097 /* Update statistics */ 2098 f->pcnt++; 2099 f->bcnt += pktlen; 2100 f->timestamp = time_second; 2101 IPFW_UNLOCK(chain); 2102 return retval; 2103 2104pullup_failed: 2105 if (fw_verbose) 2106 printf("ipfw: pullup failed\n"); 2107 return(IP_FW_PORT_DENY_FLAG); 2108} 2109 2110/* 2111 * When a rule is added/deleted, clear the next_rule pointers in all rules. 2112 * These will be reconstructed on the fly as packets are matched. 2113 */ 2114static void 2115flush_rule_ptrs(struct ip_fw_chain *chain) 2116{ 2117 struct ip_fw *rule; 2118 2119 IPFW_LOCK_ASSERT(chain); 2120 2121 for (rule = chain->rules; rule; rule = rule->next) 2122 rule->next_rule = NULL; 2123} 2124 2125/* 2126 * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given 2127 * pipe/queue, or to all of them (match == NULL). 2128 */ 2129void 2130flush_pipe_ptrs(struct dn_flow_set *match) 2131{ 2132 struct ip_fw *rule; 2133 2134 IPFW_LOCK(&layer3_chain); 2135 for (rule = layer3_chain.rules; rule; rule = rule->next) { 2136 ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); 2137 2138 if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) 2139 continue; 2140 /* 2141 * XXX Use bcmp/bzero to handle pipe_ptr to overcome 2142 * possible alignment problems on 64-bit architectures. 2143 * This code is seldom used so we do not worry too 2144 * much about efficiency. 2145 */ 2146 if (match == NULL || 2147 !bcmp(&cmd->pipe_ptr, &match, sizeof(match)) ) 2148 bzero(&cmd->pipe_ptr, sizeof(cmd->pipe_ptr)); 2149 } 2150 IPFW_UNLOCK(&layer3_chain); 2151} 2152 2153/* 2154 * Add a new rule to the list. Copy the rule into a malloc'ed area, then 2155 * possibly create a rule number and add the rule to the list. 2156 * Update the rule_number in the input struct so the caller knows it as well. 2157 */ 2158static int 2159add_rule(struct ip_fw_chain *chain, struct ip_fw *input_rule) 2160{ 2161 struct ip_fw *rule, *f, *prev; 2162 int l = RULESIZE(input_rule); 2163 2164 if (chain->rules == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) 2165 return (EINVAL); 2166 2167 rule = malloc(l, M_IPFW, M_NOWAIT | M_ZERO); 2168 if (rule == NULL) 2169 return (ENOSPC); 2170 2171 bcopy(input_rule, rule, l); 2172 2173 rule->next = NULL; 2174 rule->next_rule = NULL; 2175 2176 rule->pcnt = 0; 2177 rule->bcnt = 0; 2178 rule->timestamp = 0; 2179 2180 IPFW_LOCK(chain); 2181 2182 if (chain->rules == NULL) { /* default rule */ 2183 chain->rules = rule; 2184 goto done; 2185 } 2186 2187 /* 2188 * If rulenum is 0, find highest numbered rule before the 2189 * default rule, and add autoinc_step 2190 */ 2191 if (autoinc_step < 1) 2192 autoinc_step = 1; 2193 else if (autoinc_step > 1000) 2194 autoinc_step = 1000; 2195 if (rule->rulenum == 0) { 2196 /* 2197 * locate the highest numbered rule before default 2198 */ 2199 for (f = chain->rules; f; f = f->next) { 2200 if (f->rulenum == IPFW_DEFAULT_RULE) 2201 break; 2202 rule->rulenum = f->rulenum; 2203 } 2204 if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) 2205 rule->rulenum += autoinc_step; 2206 input_rule->rulenum = rule->rulenum; 2207 } 2208 2209 /* 2210 * Now insert the new rule in the right place in the sorted list. 2211 */ 2212 for (prev = NULL, f = chain->rules; f; prev = f, f = f->next) { 2213 if (f->rulenum > rule->rulenum) { /* found the location */ 2214 if (prev) { 2215 rule->next = f; 2216 prev->next = rule; 2217 } else { /* head insert */ 2218 rule->next = chain->rules; 2219 chain->rules = rule; 2220 } 2221 break; 2222 } 2223 } 2224 flush_rule_ptrs(chain); 2225done: 2226 static_count++; 2227 static_len += l; 2228 IPFW_UNLOCK(chain); 2229 DEB(printf("ipfw: installed rule %d, static count now %d\n", 2230 rule->rulenum, static_count);) 2231 return (0); 2232} 2233 2234/** 2235 * Remove a static rule (including derived * dynamic rules) 2236 * and place it on the ``reap list'' for later reclamation. 2237 * The caller is in charge of clearing rule pointers to avoid 2238 * dangling pointers. 2239 * @return a pointer to the next entry. 2240 * Arguments are not checked, so they better be correct. 2241 */ 2242static struct ip_fw * 2243remove_rule(struct ip_fw_chain *chain, struct ip_fw *rule, struct ip_fw *prev) 2244{ 2245 struct ip_fw *n; 2246 int l = RULESIZE(rule); 2247 2248 IPFW_LOCK_ASSERT(chain); 2249 2250 n = rule->next; 2251 IPFW_DYN_LOCK(); 2252 remove_dyn_rule(rule, NULL /* force removal */); 2253 IPFW_DYN_UNLOCK(); 2254 if (prev == NULL) 2255 chain->rules = n; 2256 else 2257 prev->next = n; 2258 static_count--; 2259 static_len -= l; 2260 2261 rule->next = chain->reap; 2262 chain->reap = rule; 2263 2264 return n; 2265} 2266 2267/** 2268 * Reclaim storage associated with a list of rules. This is 2269 * typically the list created using remove_rule. 2270 */ 2271static void 2272reap_rules(struct ip_fw *head) 2273{ 2274 struct ip_fw *rule; 2275 2276 while ((rule = head) != NULL) { 2277 head = head->next; 2278 if (DUMMYNET_LOADED) 2279 ip_dn_ruledel_ptr(rule); 2280 free(rule, M_IPFW); 2281 } 2282} 2283 2284/* 2285 * Remove all rules from a chain (except rules in set RESVD_SET 2286 * unless kill_default = 1). The caller is responsible for 2287 * reclaiming storage for the rules left in chain->reap. 2288 */ 2289static void 2290free_chain(struct ip_fw_chain *chain, int kill_default) 2291{ 2292 struct ip_fw *prev, *rule; 2293 2294 IPFW_LOCK_ASSERT(chain); 2295 2296 flush_rule_ptrs(chain); /* more efficient to do outside the loop */ 2297 for (prev = NULL, rule = chain->rules; rule ; ) 2298 if (kill_default || rule->set != RESVD_SET) 2299 rule = remove_rule(chain, rule, prev); 2300 else { 2301 prev = rule; 2302 rule = rule->next; 2303 } 2304} 2305 2306/** 2307 * Remove all rules with given number, and also do set manipulation. 2308 * Assumes chain != NULL && *chain != NULL. 2309 * 2310 * The argument is an u_int32_t. The low 16 bit are the rule or set number, 2311 * the next 8 bits are the new set, the top 8 bits are the command: 2312 * 2313 * 0 delete rules with given number 2314 * 1 delete rules with given set number 2315 * 2 move rules with given number to new set 2316 * 3 move rules with given set number to new set 2317 * 4 swap sets with given numbers 2318 */ 2319static int 2320del_entry(struct ip_fw_chain *chain, u_int32_t arg) 2321{ 2322 struct ip_fw *prev = NULL, *rule; 2323 u_int16_t rulenum; /* rule or old_set */ 2324 u_int8_t cmd, new_set; 2325 2326 rulenum = arg & 0xffff; 2327 cmd = (arg >> 24) & 0xff; 2328 new_set = (arg >> 16) & 0xff; 2329 2330 if (cmd > 4) 2331 return EINVAL; 2332 if (new_set > RESVD_SET) 2333 return EINVAL; 2334 if (cmd == 0 || cmd == 2) { 2335 if (rulenum >= IPFW_DEFAULT_RULE) 2336 return EINVAL; 2337 } else { 2338 if (rulenum > RESVD_SET) /* old_set */ 2339 return EINVAL; 2340 } 2341 2342 IPFW_LOCK(chain); 2343 rule = chain->rules; 2344 chain->reap = NULL; 2345 switch (cmd) { 2346 case 0: /* delete rules with given number */ 2347 /* 2348 * locate first rule to delete 2349 */ 2350 for (; rule->rulenum < rulenum; prev = rule, rule = rule->next) 2351 ; 2352 if (rule->rulenum != rulenum) { 2353 IPFW_UNLOCK(chain); 2354 return EINVAL; 2355 } 2356 2357 /* 2358 * flush pointers outside the loop, then delete all matching 2359 * rules. prev remains the same throughout the cycle. 2360 */ 2361 flush_rule_ptrs(chain); 2362 while (rule->rulenum == rulenum) 2363 rule = remove_rule(chain, rule, prev); 2364 break; 2365 2366 case 1: /* delete all rules with given set number */ 2367 flush_rule_ptrs(chain); 2368 rule = chain->rules; 2369 while (rule->rulenum < IPFW_DEFAULT_RULE) 2370 if (rule->set == rulenum) 2371 rule = remove_rule(chain, rule, prev); 2372 else { 2373 prev = rule; 2374 rule = rule->next; 2375 } 2376 break; 2377 2378 case 2: /* move rules with given number to new set */ 2379 rule = chain->rules; 2380 for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) 2381 if (rule->rulenum == rulenum) 2382 rule->set = new_set; 2383 break; 2384 2385 case 3: /* move rules with given set number to new set */ 2386 for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) 2387 if (rule->set == rulenum) 2388 rule->set = new_set; 2389 break; 2390 2391 case 4: /* swap two sets */ 2392 for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) 2393 if (rule->set == rulenum) 2394 rule->set = new_set; 2395 else if (rule->set == new_set) 2396 rule->set = rulenum; 2397 break; 2398 } 2399 /* 2400 * Look for rules to reclaim. We grab the list before 2401 * releasing the lock then reclaim them w/o the lock to 2402 * avoid a LOR with dummynet. 2403 */ 2404 rule = chain->reap; 2405 chain->reap = NULL; 2406 IPFW_UNLOCK(chain); 2407 if (rule) 2408 reap_rules(rule); 2409 return 0; 2410} 2411 2412/* 2413 * Clear counters for a specific rule. 2414 * The enclosing "table" is assumed locked. 2415 */ 2416static void 2417clear_counters(struct ip_fw *rule, int log_only) 2418{ 2419 ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); 2420 2421 if (log_only == 0) { 2422 rule->bcnt = rule->pcnt = 0; 2423 rule->timestamp = 0; 2424 } 2425 if (l->o.opcode == O_LOG) 2426 l->log_left = l->max_log; 2427} 2428 2429/** 2430 * Reset some or all counters on firewall rules. 2431 * @arg frwl is null to clear all entries, or contains a specific 2432 * rule number. 2433 * @arg log_only is 1 if we only want to reset logs, zero otherwise. 2434 */ 2435static int 2436zero_entry(struct ip_fw_chain *chain, int rulenum, int log_only) 2437{ 2438 struct ip_fw *rule; 2439 char *msg; 2440 2441 IPFW_LOCK(chain); 2442 if (rulenum == 0) { 2443 norule_counter = 0; 2444 for (rule = chain->rules; rule; rule = rule->next) 2445 clear_counters(rule, log_only); 2446 msg = log_only ? "ipfw: All logging counts reset.\n" : 2447 "ipfw: Accounting cleared.\n"; 2448 } else { 2449 int cleared = 0; 2450 /* 2451 * We can have multiple rules with the same number, so we 2452 * need to clear them all. 2453 */ 2454 for (rule = chain->rules; rule; rule = rule->next) 2455 if (rule->rulenum == rulenum) { 2456 while (rule && rule->rulenum == rulenum) { 2457 clear_counters(rule, log_only); 2458 rule = rule->next; 2459 } 2460 cleared = 1; 2461 break; 2462 } 2463 if (!cleared) { /* we did not find any matching rules */ 2464 IPFW_UNLOCK(chain); 2465 return (EINVAL); 2466 } 2467 msg = log_only ? "ipfw: Entry %d logging count reset.\n" : 2468 "ipfw: Entry %d cleared.\n"; 2469 } 2470 IPFW_UNLOCK(chain); 2471 2472 if (fw_verbose) 2473 log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); 2474 return (0); 2475} 2476 2477/* 2478 * Check validity of the structure before insert. 2479 * Fortunately rules are simple, so this mostly need to check rule sizes. 2480 */ 2481static int 2482check_ipfw_struct(struct ip_fw *rule, int size) 2483{ 2484 int l, cmdlen = 0; 2485 int have_action=0; 2486 ipfw_insn *cmd; 2487 2488 if (size < sizeof(*rule)) { 2489 printf("ipfw: rule too short\n"); 2490 return (EINVAL); 2491 } 2492 /* first, check for valid size */ 2493 l = RULESIZE(rule); 2494 if (l != size) { 2495 printf("ipfw: size mismatch (have %d want %d)\n", size, l); 2496 return (EINVAL); 2497 } 2498 /* 2499 * Now go for the individual checks. Very simple ones, basically only 2500 * instruction sizes. 2501 */ 2502 for (l = rule->cmd_len, cmd = rule->cmd ; 2503 l > 0 ; l -= cmdlen, cmd += cmdlen) { 2504 cmdlen = F_LEN(cmd); 2505 if (cmdlen > l) { 2506 printf("ipfw: opcode %d size truncated\n", 2507 cmd->opcode); 2508 return EINVAL; 2509 } 2510 DEB(printf("ipfw: opcode %d\n", cmd->opcode);) 2511 switch (cmd->opcode) { 2512 case O_PROBE_STATE: 2513 case O_KEEP_STATE: 2514 case O_PROTO: 2515 case O_IP_SRC_ME: 2516 case O_IP_DST_ME: 2517 case O_LAYER2: 2518 case O_IN: 2519 case O_FRAG: 2520 case O_IPOPT: 2521 case O_IPTOS: 2522 case O_IPPRECEDENCE: 2523 case O_IPVER: 2524 case O_TCPWIN: 2525 case O_TCPFLAGS: 2526 case O_TCPOPTS: 2527 case O_ESTAB: 2528 case O_VERREVPATH: 2529 case O_IPSEC: 2530 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2531 goto bad_size; 2532 break; 2533 2534 case O_UID: 2535 case O_GID: 2536 case O_IP_SRC: 2537 case O_IP_DST: 2538 case O_TCPSEQ: 2539 case O_TCPACK: 2540 case O_PROB: 2541 case O_ICMPTYPE: 2542 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) 2543 goto bad_size; 2544 break; 2545 2546 case O_LIMIT: 2547 if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) 2548 goto bad_size; 2549 break; 2550 2551 case O_LOG: 2552 if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) 2553 goto bad_size; 2554 2555 ((ipfw_insn_log *)cmd)->log_left = 2556 ((ipfw_insn_log *)cmd)->max_log; 2557 2558 break; 2559 2560 case O_IP_SRC_MASK: 2561 case O_IP_DST_MASK: 2562 /* only odd command lengths */ 2563 if ( !(cmdlen & 1) || cmdlen > 31) 2564 goto bad_size; 2565 break; 2566 2567 case O_IP_SRC_SET: 2568 case O_IP_DST_SET: 2569 if (cmd->arg1 == 0 || cmd->arg1 > 256) { 2570 printf("ipfw: invalid set size %d\n", 2571 cmd->arg1); 2572 return EINVAL; 2573 } 2574 if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + 2575 (cmd->arg1+31)/32 ) 2576 goto bad_size; 2577 break; 2578 2579 case O_MACADDR2: 2580 if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) 2581 goto bad_size; 2582 break; 2583 2584 case O_NOP: 2585 case O_IPID: 2586 case O_IPTTL: 2587 case O_IPLEN: 2588 if (cmdlen < 1 || cmdlen > 31) 2589 goto bad_size; 2590 break; 2591 2592 case O_MAC_TYPE: 2593 case O_IP_SRCPORT: 2594 case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ 2595 if (cmdlen < 2 || cmdlen > 31) 2596 goto bad_size; 2597 break; 2598 2599 case O_RECV: 2600 case O_XMIT: 2601 case O_VIA: 2602 if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) 2603 goto bad_size; 2604 break; 2605 2606 case O_PIPE: 2607 case O_QUEUE: 2608 if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) 2609 goto bad_size; 2610 goto check_action; 2611 2612 case O_FORWARD_IP: 2613 if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) 2614 goto bad_size; 2615 goto check_action; 2616 2617 case O_FORWARD_MAC: /* XXX not implemented yet */ 2618 case O_CHECK_STATE: 2619 case O_COUNT: 2620 case O_ACCEPT: 2621 case O_DENY: 2622 case O_REJECT: 2623 case O_SKIPTO: 2624 case O_DIVERT: 2625 case O_TEE: 2626 if (cmdlen != F_INSN_SIZE(ipfw_insn)) 2627 goto bad_size; 2628check_action: 2629 if (have_action) { 2630 printf("ipfw: opcode %d, multiple actions" 2631 " not allowed\n", 2632 cmd->opcode); 2633 return EINVAL; 2634 } 2635 have_action = 1; 2636 if (l != cmdlen) { 2637 printf("ipfw: opcode %d, action must be" 2638 " last opcode\n", 2639 cmd->opcode); 2640 return EINVAL; 2641 } 2642 break; 2643 default: 2644 printf("ipfw: opcode %d, unknown opcode\n", 2645 cmd->opcode); 2646 return EINVAL; 2647 } 2648 } 2649 if (have_action == 0) { 2650 printf("ipfw: missing action\n"); 2651 return EINVAL; 2652 } 2653 return 0; 2654 2655bad_size: 2656 printf("ipfw: opcode %d size %d wrong\n", 2657 cmd->opcode, cmdlen); 2658 return EINVAL; 2659} 2660 2661/* 2662 * Copy the static and dynamic rules to the supplied buffer 2663 * and return the amount of space actually used. 2664 */ 2665static size_t 2666ipfw_getrules(struct ip_fw_chain *chain, void *buf, size_t space) 2667{ 2668 char *bp = buf; 2669 char *ep = bp + space; 2670 struct ip_fw *rule; 2671 int i; 2672 2673 /* XXX this can take a long time and locking will block packet flow */ 2674 IPFW_LOCK(chain); 2675 for (rule = chain->rules; rule ; rule = rule->next) { 2676 /* 2677 * Verify the entry fits in the buffer in case the 2678 * rules changed between calculating buffer space and 2679 * now. This would be better done using a generation 2680 * number but should suffice for now. 2681 */ 2682 i = RULESIZE(rule); 2683 if (bp + i <= ep) { 2684 bcopy(rule, bp, i); 2685 bcopy(&set_disable, &(((struct ip_fw *)bp)->next_rule), 2686 sizeof(set_disable)); 2687 bp += i; 2688 } 2689 } 2690 IPFW_UNLOCK(chain); 2691 if (ipfw_dyn_v) { 2692 ipfw_dyn_rule *p, *last = NULL; 2693 2694 IPFW_DYN_LOCK(); 2695 for (i = 0 ; i < curr_dyn_buckets; i++) 2696 for (p = ipfw_dyn_v[i] ; p != NULL; p = p->next) { 2697 if (bp + sizeof *p <= ep) { 2698 ipfw_dyn_rule *dst = 2699 (ipfw_dyn_rule *)bp; 2700 bcopy(p, dst, sizeof *p); 2701 bcopy(&(p->rule->rulenum), &(dst->rule), 2702 sizeof(p->rule->rulenum)); 2703 /* 2704 * store a non-null value in "next". 2705 * The userland code will interpret a 2706 * NULL here as a marker 2707 * for the last dynamic rule. 2708 */ 2709 bcopy(&dst, &dst->next, sizeof(dst)); 2710 last = dst; 2711 dst->expire = 2712 TIME_LEQ(dst->expire, time_second) ? 2713 0 : dst->expire - time_second ; 2714 bp += sizeof(ipfw_dyn_rule); 2715 } 2716 } 2717 IPFW_DYN_UNLOCK(); 2718 if (last != NULL) /* mark last dynamic rule */ 2719 bzero(&last->next, sizeof(last)); 2720 } 2721 return (bp - (char *)buf); 2722} 2723 2724 2725/** 2726 * {set|get}sockopt parser. 2727 */ 2728static int 2729ipfw_ctl(struct sockopt *sopt) 2730{ 2731#define RULE_MAXSIZE (256*sizeof(u_int32_t)) 2732 int error, rule_num; 2733 size_t size; 2734 struct ip_fw *buf, *rule; 2735 u_int32_t rulenum[2]; 2736 2737 /* 2738 * Disallow modifications in really-really secure mode, but still allow 2739 * the logging counters to be reset. 2740 */ 2741 if (sopt->sopt_name == IP_FW_ADD || 2742 (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { 2743#if __FreeBSD_version >= 500034 2744 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); 2745 if (error) 2746 return (error); 2747#else /* FreeBSD 4.x */ 2748 if (securelevel >= 3) 2749 return (EPERM); 2750#endif 2751 } 2752 2753 error = 0; 2754 2755 switch (sopt->sopt_name) { 2756 case IP_FW_GET: 2757 /* 2758 * pass up a copy of the current rules. Static rules 2759 * come first (the last of which has number IPFW_DEFAULT_RULE), 2760 * followed by a possibly empty list of dynamic rule. 2761 * The last dynamic rule has NULL in the "next" field. 2762 * 2763 * Note that the calculated size is used to bound the 2764 * amount of data returned to the user. The rule set may 2765 * change between calculating the size and returning the 2766 * data in which case we'll just return what fits. 2767 */ 2768 size = static_len; /* size of static rules */ 2769 if (ipfw_dyn_v) /* add size of dyn.rules */ 2770 size += (dyn_count * sizeof(ipfw_dyn_rule)); 2771 2772 /* 2773 * XXX todo: if the user passes a short length just to know 2774 * how much room is needed, do not bother filling up the 2775 * buffer, just jump to the sooptcopyout. 2776 */ 2777 buf = malloc(size, M_TEMP, M_WAITOK); 2778 error = sooptcopyout(sopt, buf, 2779 ipfw_getrules(&layer3_chain, buf, size)); 2780 free(buf, M_TEMP); 2781 break; 2782 2783 case IP_FW_FLUSH: 2784 /* 2785 * Normally we cannot release the lock on each iteration. 2786 * We could do it here only because we start from the head all 2787 * the times so there is no risk of missing some entries. 2788 * On the other hand, the risk is that we end up with 2789 * a very inconsistent ruleset, so better keep the lock 2790 * around the whole cycle. 2791 * 2792 * XXX this code can be improved by resetting the head of 2793 * the list to point to the default rule, and then freeing 2794 * the old list without the need for a lock. 2795 */ 2796 2797 IPFW_LOCK(&layer3_chain); 2798 layer3_chain.reap = NULL; 2799 free_chain(&layer3_chain, 0 /* keep default rule */); 2800 rule = layer3_chain.reap, layer3_chain.reap = NULL; 2801 IPFW_UNLOCK(&layer3_chain); 2802 if (layer3_chain.reap != NULL) 2803 reap_rules(rule); 2804 break; 2805 2806 case IP_FW_ADD: 2807 rule = malloc(RULE_MAXSIZE, M_TEMP, M_WAITOK); 2808 error = sooptcopyin(sopt, rule, RULE_MAXSIZE, 2809 sizeof(struct ip_fw) ); 2810 if (error == 0) 2811 error = check_ipfw_struct(rule, sopt->sopt_valsize); 2812 if (error == 0) { 2813 error = add_rule(&layer3_chain, rule); 2814 size = RULESIZE(rule); 2815 if (!error && sopt->sopt_dir == SOPT_GET) 2816 error = sooptcopyout(sopt, rule, size); 2817 } 2818 free(rule, M_TEMP); 2819 break; 2820 2821 case IP_FW_DEL: 2822 /* 2823 * IP_FW_DEL is used for deleting single rules or sets, 2824 * and (ab)used to atomically manipulate sets. Argument size 2825 * is used to distinguish between the two: 2826 * sizeof(u_int32_t) 2827 * delete single rule or set of rules, 2828 * or reassign rules (or sets) to a different set. 2829 * 2*sizeof(u_int32_t) 2830 * atomic disable/enable sets. 2831 * first u_int32_t contains sets to be disabled, 2832 * second u_int32_t contains sets to be enabled. 2833 */ 2834 error = sooptcopyin(sopt, rulenum, 2835 2*sizeof(u_int32_t), sizeof(u_int32_t)); 2836 if (error) 2837 break; 2838 size = sopt->sopt_valsize; 2839 if (size == sizeof(u_int32_t)) /* delete or reassign */ 2840 error = del_entry(&layer3_chain, rulenum[0]); 2841 else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ 2842 set_disable = 2843 (set_disable | rulenum[0]) & ~rulenum[1] & 2844 ~(1<<RESVD_SET); /* set RESVD_SET always enabled */ 2845 else 2846 error = EINVAL; 2847 break; 2848 2849 case IP_FW_ZERO: 2850 case IP_FW_RESETLOG: /* argument is an int, the rule number */ 2851 rule_num = 0; 2852 if (sopt->sopt_val != 0) { 2853 error = sooptcopyin(sopt, &rule_num, 2854 sizeof(int), sizeof(int)); 2855 if (error) 2856 break; 2857 } 2858 error = zero_entry(&layer3_chain, rule_num, 2859 sopt->sopt_name == IP_FW_RESETLOG); 2860 break; 2861 2862 default: 2863 printf("ipfw: ipfw_ctl invalid option %d\n", sopt->sopt_name); 2864 error = EINVAL; 2865 } 2866 2867 return (error); 2868#undef RULE_MAXSIZE 2869} 2870 2871/** 2872 * dummynet needs a reference to the default rule, because rules can be 2873 * deleted while packets hold a reference to them. When this happens, 2874 * dummynet changes the reference to the default rule (it could well be a 2875 * NULL pointer, but this way we do not need to check for the special 2876 * case, plus here he have info on the default behaviour). 2877 */ 2878struct ip_fw *ip_fw_default_rule; 2879 2880/* 2881 * This procedure is only used to handle keepalives. It is invoked 2882 * every dyn_keepalive_period 2883 */ 2884static void 2885ipfw_tick(void * __unused unused) 2886{ 2887 int i; 2888 ipfw_dyn_rule *q; 2889 2890 if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) 2891 goto done; 2892 2893 IPFW_DYN_LOCK(); 2894 for (i = 0 ; i < curr_dyn_buckets ; i++) { 2895 for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { 2896 if (q->dyn_type == O_LIMIT_PARENT) 2897 continue; 2898 if (q->id.proto != IPPROTO_TCP) 2899 continue; 2900 if ( (q->state & BOTH_SYN) != BOTH_SYN) 2901 continue; 2902 if (TIME_LEQ( time_second+dyn_keepalive_interval, 2903 q->expire)) 2904 continue; /* too early */ 2905 if (TIME_LEQ(q->expire, time_second)) 2906 continue; /* too late, rule expired */ 2907 2908 send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 2909 send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); 2910 } 2911 } 2912 IPFW_DYN_UNLOCK(); 2913done: 2914 callout_reset(&ipfw_timeout, dyn_keepalive_period*hz, ipfw_tick, NULL); 2915} 2916 2917static int 2918ipfw_init(void) 2919{ 2920 struct ip_fw default_rule; 2921 int error; 2922 2923 layer3_chain.rules = NULL; 2924 IPFW_LOCK_INIT(&layer3_chain); 2925 IPFW_DYN_LOCK_INIT(); 2926 callout_init(&ipfw_timeout, debug_mpsafenet ? CALLOUT_MPSAFE : 0); 2927 2928 bzero(&default_rule, sizeof default_rule); 2929 2930 default_rule.act_ofs = 0; 2931 default_rule.rulenum = IPFW_DEFAULT_RULE; 2932 default_rule.cmd_len = 1; 2933 default_rule.set = RESVD_SET; 2934 2935 default_rule.cmd[0].len = 1; 2936 default_rule.cmd[0].opcode = 2937#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 2938 1 ? O_ACCEPT : 2939#endif 2940 O_DENY; 2941 2942 error = add_rule(&layer3_chain, &default_rule); 2943 if (error != 0) { 2944 printf("ipfw2: error %u initializing default rule " 2945 "(support disabled)\n", error); 2946 IPFW_DYN_LOCK_DESTROY(); 2947 IPFW_LOCK_DESTROY(&layer3_chain); 2948 return (error); 2949 } 2950 2951 ip_fw_default_rule = layer3_chain.rules; 2952 printf("ipfw2 initialized, divert %s, " 2953 "rule-based forwarding enabled, default to %s, logging ", 2954#ifdef IPDIVERT 2955 "enabled", 2956#else 2957 "disabled", 2958#endif 2959 default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); 2960 2961#ifdef IPFIREWALL_VERBOSE 2962 fw_verbose = 1; 2963#endif 2964#ifdef IPFIREWALL_VERBOSE_LIMIT 2965 verbose_limit = IPFIREWALL_VERBOSE_LIMIT; 2966#endif 2967 if (fw_verbose == 0) 2968 printf("disabled\n"); 2969 else if (verbose_limit == 0) 2970 printf("unlimited\n"); 2971 else 2972 printf("limited to %d packets/entry by default\n", 2973 verbose_limit); 2974 2975 ip_fw_chk_ptr = ipfw_chk; 2976 ip_fw_ctl_ptr = ipfw_ctl; 2977 callout_reset(&ipfw_timeout, hz, ipfw_tick, NULL); 2978 2979 return (0); 2980} 2981 2982static void 2983ipfw_destroy(void) 2984{ 2985 struct ip_fw *reap; 2986 2987 IPFW_LOCK(&layer3_chain); 2988 callout_stop(&ipfw_timeout); 2989 ip_fw_chk_ptr = NULL; 2990 ip_fw_ctl_ptr = NULL; 2991 layer3_chain.reap = NULL; 2992 free_chain(&layer3_chain, 1 /* kill default rule */); 2993 reap = layer3_chain.reap, layer3_chain.reap = NULL; 2994 IPFW_UNLOCK(&layer3_chain); 2995 if (reap != NULL) 2996 reap_rules(reap); 2997 2998 IPFW_DYN_LOCK_DESTROY(); 2999 IPFW_LOCK_DESTROY(&layer3_chain); 3000 printf("IP firewall unloaded\n"); 3001} 3002 3003static int 3004ipfw_modevent(module_t mod, int type, void *unused) 3005{ 3006 int err = 0; 3007 3008 switch (type) { 3009 case MOD_LOAD: 3010 if (IPFW_LOADED) { 3011 printf("IP firewall already loaded\n"); 3012 err = EEXIST; 3013 } else { 3014 err = ipfw_init(); 3015 } 3016 break; 3017 3018 case MOD_UNLOAD: 3019 ipfw_destroy(); 3020 err = 0; 3021 break; 3022 default: 3023 break; 3024 } 3025 return err; 3026} 3027 3028static moduledata_t ipfwmod = { 3029 "ipfw", 3030 ipfw_modevent, 3031 0 3032}; 3033DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); 3034MODULE_VERSION(ipfw, 1); 3035#endif /* IPFW2 */ 3036