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 26 #include <sys/cdefs.h> 27 __FBSDID("$FreeBSD$"); 28 29 #define DEB(x) 30 #define DDB(x) x 31 32 /* 33 * Dynamic rule support for ipfw 34 */ 35 36 #include "opt_ipfw.h" 37 #include "opt_inet.h" 38 #ifndef INET 39 #error IPFIREWALL requires INET. 40 #endif /* INET */ 41 #include "opt_inet6.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/socket.h> 50 #include <sys/sysctl.h> 51 #include <sys/syslog.h> 52 #include <net/ethernet.h> /* for ETHERTYPE_IP */ 53 #include <net/if.h> 54 #include <net/vnet.h> 55 56 #include <netinet/in.h> 57 #include <netinet/ip.h> 58 #include <netinet/ip_var.h> /* ip_defttl */ 59 #include <netinet/ip_fw.h> 60 #include <netinet/tcp_var.h> 61 #include <netinet/udp.h> 62 63 #include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */ 64 #ifdef INET6 65 #include <netinet6/in6_var.h> 66 #include <netinet6/ip6_var.h> 67 #endif 68 69 #include <netpfil/ipfw/ip_fw_private.h> 70 71 #include <machine/in_cksum.h> /* XXX for in_cksum */ 72 73 #ifdef MAC 74 #include <security/mac/mac_framework.h> 75 #endif 76 77 /* 78 * Description of dynamic rules. 79 * 80 * Dynamic rules are stored in lists accessed through a hash table 81 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 82 * be modified through the sysctl variable dyn_buckets which is 83 * updated when the table becomes empty. 84 * 85 * XXX currently there is only one list, ipfw_dyn. 86 * 87 * When a packet is received, its address fields are first masked 88 * with the mask defined for the rule, then hashed, then matched 89 * against the entries in the corresponding list. 90 * Dynamic rules can be used for different purposes: 91 * + stateful rules; 92 * + enforcing limits on the number of sessions; 93 * + in-kernel NAT (not implemented yet) 94 * 95 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 96 * measured in seconds and depending on the flags. 97 * 98 * The total number of dynamic rules is stored in dyn_count. 99 * The max number of dynamic rules is dyn_max. When we reach 100 * the maximum number of rules we do not create anymore. This is 101 * done to avoid consuming too much memory, but also too much 102 * time when searching on each packet (ideally, we should try instead 103 * to put a limit on the length of the list on each bucket...). 104 * 105 * Each dynamic rule holds a pointer to the parent ipfw rule so 106 * we know what action to perform. Dynamic rules are removed when 107 * the parent rule is deleted. XXX we should make them survive. 108 * 109 * There are some limitations with dynamic rules -- we do not 110 * obey the 'randomized match', and we do not do multiple 111 * passes through the firewall. XXX check the latter!!! 112 */ 113 114 /* 115 * Static variables followed by global ones 116 */ 117 static VNET_DEFINE(ipfw_dyn_rule **, ipfw_dyn_v); 118 static VNET_DEFINE(u_int32_t, dyn_buckets); 119 static VNET_DEFINE(u_int32_t, curr_dyn_buckets); 120 static VNET_DEFINE(struct callout, ipfw_timeout); 121 #define V_ipfw_dyn_v VNET(ipfw_dyn_v) 122 #define V_dyn_buckets VNET(dyn_buckets) 123 #define V_curr_dyn_buckets VNET(curr_dyn_buckets) 124 #define V_ipfw_timeout VNET(ipfw_timeout) 125 126 static uma_zone_t ipfw_dyn_rule_zone; 127 #ifndef __FreeBSD__ 128 DEFINE_SPINLOCK(ipfw_dyn_mtx); 129 #else 130 static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */ 131 #endif 132 133 #define IPFW_DYN_LOCK_INIT() \ 134 mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF) 135 #define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx) 136 #define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx) 137 #define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx) 138 #define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED) 139 140 void 141 ipfw_dyn_unlock(void) 142 { 143 IPFW_DYN_UNLOCK(); 144 } 145 146 /* 147 * Timeouts for various events in handing dynamic rules. 148 */ 149 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime); 150 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime); 151 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime); 152 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime); 153 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime); 154 static VNET_DEFINE(u_int32_t, dyn_short_lifetime); 155 156 #define V_dyn_ack_lifetime VNET(dyn_ack_lifetime) 157 #define V_dyn_syn_lifetime VNET(dyn_syn_lifetime) 158 #define V_dyn_fin_lifetime VNET(dyn_fin_lifetime) 159 #define V_dyn_rst_lifetime VNET(dyn_rst_lifetime) 160 #define V_dyn_udp_lifetime VNET(dyn_udp_lifetime) 161 #define V_dyn_short_lifetime VNET(dyn_short_lifetime) 162 163 /* 164 * Keepalives are sent if dyn_keepalive is set. They are sent every 165 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 166 * seconds of lifetime of a rule. 167 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 168 * than dyn_keepalive_period. 169 */ 170 171 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval); 172 static VNET_DEFINE(u_int32_t, dyn_keepalive_period); 173 static VNET_DEFINE(u_int32_t, dyn_keepalive); 174 175 #define V_dyn_keepalive_interval VNET(dyn_keepalive_interval) 176 #define V_dyn_keepalive_period VNET(dyn_keepalive_period) 177 #define V_dyn_keepalive VNET(dyn_keepalive) 178 179 static VNET_DEFINE(u_int32_t, dyn_count); /* # of dynamic rules */ 180 static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */ 181 182 #define V_dyn_count VNET(dyn_count) 183 #define V_dyn_max VNET(dyn_max) 184 185 #ifdef SYSCTL_NODE 186 187 SYSBEGIN(f2) 188 189 SYSCTL_DECL(_net_inet_ip_fw); 190 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, 191 CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0, 192 "Number of dyn. buckets"); 193 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, 194 CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0, 195 "Current Number of dyn. buckets"); 196 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_count, 197 CTLFLAG_RD, &VNET_NAME(dyn_count), 0, 198 "Number of dyn. rules"); 199 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_max, 200 CTLFLAG_RW, &VNET_NAME(dyn_max), 0, 201 "Max number of dyn. rules"); 202 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, 203 CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0, 204 "Lifetime of dyn. rules for acks"); 205 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, 206 CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0, 207 "Lifetime of dyn. rules for syn"); 208 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, 209 CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0, 210 "Lifetime of dyn. rules for fin"); 211 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, 212 CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0, 213 "Lifetime of dyn. rules for rst"); 214 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, 215 CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0, 216 "Lifetime of dyn. rules for UDP"); 217 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, 218 CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0, 219 "Lifetime of dyn. rules for other situations"); 220 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, 221 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0, 222 "Enable keepalives for dyn. rules"); 223 224 SYSEND 225 226 #endif /* SYSCTL_NODE */ 227 228 229 static __inline int 230 hash_packet6(struct ipfw_flow_id *id) 231 { 232 u_int32_t i; 233 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^ 234 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^ 235 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^ 236 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^ 237 (id->dst_port) ^ (id->src_port); 238 return i; 239 } 240 241 /* 242 * IMPORTANT: the hash function for dynamic rules must be commutative 243 * in source and destination (ip,port), because rules are bidirectional 244 * and we want to find both in the same bucket. 245 */ 246 static __inline int 247 hash_packet(struct ipfw_flow_id *id) 248 { 249 u_int32_t i; 250 251 #ifdef INET6 252 if (IS_IP6_FLOW_ID(id)) 253 i = hash_packet6(id); 254 else 255 #endif /* INET6 */ 256 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 257 i &= (V_curr_dyn_buckets - 1); 258 return i; 259 } 260 261 static __inline void 262 unlink_dyn_rule_print(struct ipfw_flow_id *id) 263 { 264 struct in_addr da; 265 #ifdef INET6 266 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN]; 267 #else 268 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN]; 269 #endif 270 271 #ifdef INET6 272 if (IS_IP6_FLOW_ID(id)) { 273 ip6_sprintf(src, &id->src_ip6); 274 ip6_sprintf(dst, &id->dst_ip6); 275 } else 276 #endif 277 { 278 da.s_addr = htonl(id->src_ip); 279 inet_ntop(AF_INET, &da, src, sizeof(src)); 280 da.s_addr = htonl(id->dst_ip); 281 inet_ntop(AF_INET, &da, dst, sizeof(dst)); 282 } 283 printf("ipfw: unlink entry %s %d -> %s %d, %d left\n", 284 src, id->src_port, dst, id->dst_port, V_dyn_count - 1); 285 } 286 287 /** 288 * unlink a dynamic rule from a chain. prev is a pointer to 289 * the previous one, q is a pointer to the rule to delete, 290 * head is a pointer to the head of the queue. 291 * Modifies q and potentially also head. 292 */ 293 #define UNLINK_DYN_RULE(prev, head, q) { \ 294 ipfw_dyn_rule *old_q = q; \ 295 \ 296 /* remove a refcount to the parent */ \ 297 if (q->dyn_type == O_LIMIT) \ 298 q->parent->count--; \ 299 DEB(unlink_dyn_rule_print(&q->id);) \ 300 if (prev != NULL) \ 301 prev->next = q = q->next; \ 302 else \ 303 head = q = q->next; \ 304 V_dyn_count--; \ 305 uma_zfree(ipfw_dyn_rule_zone, old_q); } 306 307 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 308 309 /** 310 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 311 * 312 * If keep_me == NULL, rules are deleted even if not expired, 313 * otherwise only expired rules are removed. 314 * 315 * The value of the second parameter is also used to point to identify 316 * a rule we absolutely do not want to remove (e.g. because we are 317 * holding a reference to it -- this is the case with O_LIMIT_PARENT 318 * rules). The pointer is only used for comparison, so any non-null 319 * value will do. 320 */ 321 static void 322 remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 323 { 324 static u_int32_t last_remove = 0; 325 326 #define FORCE (keep_me == NULL) 327 328 ipfw_dyn_rule *prev, *q; 329 int i, pass = 0, max_pass = 0; 330 331 IPFW_DYN_LOCK_ASSERT(); 332 333 if (V_ipfw_dyn_v == NULL || V_dyn_count == 0) 334 return; 335 /* do not expire more than once per second, it is useless */ 336 if (!FORCE && last_remove == time_uptime) 337 return; 338 last_remove = time_uptime; 339 340 /* 341 * because O_LIMIT refer to parent rules, during the first pass only 342 * remove child and mark any pending LIMIT_PARENT, and remove 343 * them in a second pass. 344 */ 345 next_pass: 346 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 347 for (prev=NULL, q = V_ipfw_dyn_v[i] ; q ; ) { 348 /* 349 * Logic can become complex here, so we split tests. 350 */ 351 if (q == keep_me) 352 goto next; 353 if (rule != NULL && rule != q->rule) 354 goto next; /* not the one we are looking for */ 355 if (q->dyn_type == O_LIMIT_PARENT) { 356 /* 357 * handle parent in the second pass, 358 * record we need one. 359 */ 360 max_pass = 1; 361 if (pass == 0) 362 goto next; 363 if (FORCE && q->count != 0 ) { 364 /* XXX should not happen! */ 365 printf("ipfw: OUCH! cannot remove rule," 366 " count %d\n", q->count); 367 } 368 } else { 369 if (!FORCE && 370 !TIME_LEQ( q->expire, time_uptime )) 371 goto next; 372 } 373 if (q->dyn_type != O_LIMIT_PARENT || !q->count) { 374 UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q); 375 continue; 376 } 377 next: 378 prev=q; 379 q=q->next; 380 } 381 } 382 if (pass++ < max_pass) 383 goto next_pass; 384 } 385 386 void 387 ipfw_remove_dyn_children(struct ip_fw *rule) 388 { 389 IPFW_DYN_LOCK(); 390 remove_dyn_rule(rule, NULL /* force removal */); 391 IPFW_DYN_UNLOCK(); 392 } 393 394 /* 395 * Lookup a dynamic rule, locked version. 396 */ 397 static ipfw_dyn_rule * 398 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction, 399 struct tcphdr *tcp) 400 { 401 /* 402 * Stateful ipfw extensions. 403 * Lookup into dynamic session queue. 404 */ 405 #define MATCH_REVERSE 0 406 #define MATCH_FORWARD 1 407 #define MATCH_NONE 2 408 #define MATCH_UNKNOWN 3 409 int i, dir = MATCH_NONE; 410 ipfw_dyn_rule *prev, *q = NULL; 411 412 IPFW_DYN_LOCK_ASSERT(); 413 414 if (V_ipfw_dyn_v == NULL) 415 goto done; /* not found */ 416 i = hash_packet(pkt); 417 for (prev = NULL, q = V_ipfw_dyn_v[i]; q != NULL;) { 418 if (q->dyn_type == O_LIMIT_PARENT && q->count) 419 goto next; 420 if (TIME_LEQ(q->expire, time_uptime)) { /* expire entry */ 421 UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q); 422 continue; 423 } 424 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT) 425 goto next; 426 427 if (IS_IP6_FLOW_ID(pkt)) { 428 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) && 429 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) && 430 pkt->src_port == q->id.src_port && 431 pkt->dst_port == q->id.dst_port) { 432 dir = MATCH_FORWARD; 433 break; 434 } 435 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) && 436 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) && 437 pkt->src_port == q->id.dst_port && 438 pkt->dst_port == q->id.src_port) { 439 dir = MATCH_REVERSE; 440 break; 441 } 442 } else { 443 if (pkt->src_ip == q->id.src_ip && 444 pkt->dst_ip == q->id.dst_ip && 445 pkt->src_port == q->id.src_port && 446 pkt->dst_port == q->id.dst_port) { 447 dir = MATCH_FORWARD; 448 break; 449 } 450 if (pkt->src_ip == q->id.dst_ip && 451 pkt->dst_ip == q->id.src_ip && 452 pkt->src_port == q->id.dst_port && 453 pkt->dst_port == q->id.src_port) { 454 dir = MATCH_REVERSE; 455 break; 456 } 457 } 458 next: 459 prev = q; 460 q = q->next; 461 } 462 if (q == NULL) 463 goto done; /* q = NULL, not found */ 464 465 if (prev != NULL) { /* found and not in front */ 466 prev->next = q->next; 467 q->next = V_ipfw_dyn_v[i]; 468 V_ipfw_dyn_v[i] = q; 469 } 470 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 471 uint32_t ack; 472 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST); 473 474 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 475 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 476 #define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8)) 477 #define ACK_FWD 0x10000 /* fwd ack seen */ 478 #define ACK_REV 0x20000 /* rev ack seen */ 479 480 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8); 481 switch (q->state & TCP_FLAGS) { 482 case TH_SYN: /* opening */ 483 q->expire = time_uptime + V_dyn_syn_lifetime; 484 break; 485 486 case BOTH_SYN: /* move to established */ 487 case BOTH_SYN | TH_FIN: /* one side tries to close */ 488 case BOTH_SYN | (TH_FIN << 8): 489 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 490 if (tcp == NULL) 491 break; 492 493 ack = ntohl(tcp->th_ack); 494 if (dir == MATCH_FORWARD) { 495 if (q->ack_fwd == 0 || 496 _SEQ_GE(ack, q->ack_fwd)) { 497 q->ack_fwd = ack; 498 q->state |= ACK_FWD; 499 } 500 } else { 501 if (q->ack_rev == 0 || 502 _SEQ_GE(ack, q->ack_rev)) { 503 q->ack_rev = ack; 504 q->state |= ACK_REV; 505 } 506 } 507 if ((q->state & (ACK_FWD | ACK_REV)) == 508 (ACK_FWD | ACK_REV)) { 509 q->expire = time_uptime + V_dyn_ack_lifetime; 510 q->state &= ~(ACK_FWD | ACK_REV); 511 } 512 break; 513 514 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 515 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period) 516 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1; 517 q->expire = time_uptime + V_dyn_fin_lifetime; 518 break; 519 520 default: 521 #if 0 522 /* 523 * reset or some invalid combination, but can also 524 * occur if we use keep-state the wrong way. 525 */ 526 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 527 printf("invalid state: 0x%x\n", q->state); 528 #endif 529 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period) 530 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1; 531 q->expire = time_uptime + V_dyn_rst_lifetime; 532 break; 533 } 534 } else if (pkt->proto == IPPROTO_UDP) { 535 q->expire = time_uptime + V_dyn_udp_lifetime; 536 } else { 537 /* other protocols */ 538 q->expire = time_uptime + V_dyn_short_lifetime; 539 } 540 done: 541 if (match_direction != NULL) 542 *match_direction = dir; 543 return (q); 544 } 545 546 ipfw_dyn_rule * 547 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 548 struct tcphdr *tcp) 549 { 550 ipfw_dyn_rule *q; 551 552 IPFW_DYN_LOCK(); 553 q = lookup_dyn_rule_locked(pkt, match_direction, tcp); 554 if (q == NULL) 555 IPFW_DYN_UNLOCK(); 556 /* NB: return table locked when q is not NULL */ 557 return q; 558 } 559 560 static void 561 realloc_dynamic_table(void) 562 { 563 IPFW_DYN_LOCK_ASSERT(); 564 565 /* 566 * Try reallocation, make sure we have a power of 2 and do 567 * not allow more than 64k entries. In case of overflow, 568 * default to 1024. 569 */ 570 571 if (V_dyn_buckets > 65536) 572 V_dyn_buckets = 1024; 573 if ((V_dyn_buckets & (V_dyn_buckets-1)) != 0) { /* not a power of 2 */ 574 V_dyn_buckets = V_curr_dyn_buckets; /* reset */ 575 return; 576 } 577 V_curr_dyn_buckets = V_dyn_buckets; 578 if (V_ipfw_dyn_v != NULL) 579 free(V_ipfw_dyn_v, M_IPFW); 580 for (;;) { 581 V_ipfw_dyn_v = malloc(V_curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 582 M_IPFW, M_NOWAIT | M_ZERO); 583 if (V_ipfw_dyn_v != NULL || V_curr_dyn_buckets <= 2) 584 break; 585 V_curr_dyn_buckets /= 2; 586 } 587 } 588 589 /** 590 * Install state of type 'type' for a dynamic session. 591 * The hash table contains two type of rules: 592 * - regular rules (O_KEEP_STATE) 593 * - rules for sessions with limited number of sess per user 594 * (O_LIMIT). When they are created, the parent is 595 * increased by 1, and decreased on delete. In this case, 596 * the third parameter is the parent rule and not the chain. 597 * - "parent" rules for the above (O_LIMIT_PARENT). 598 */ 599 static ipfw_dyn_rule * 600 add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 601 { 602 ipfw_dyn_rule *r; 603 int i; 604 605 IPFW_DYN_LOCK_ASSERT(); 606 607 if (V_ipfw_dyn_v == NULL || 608 (V_dyn_count == 0 && V_dyn_buckets != V_curr_dyn_buckets)) { 609 realloc_dynamic_table(); 610 if (V_ipfw_dyn_v == NULL) 611 return NULL; /* failed ! */ 612 } 613 i = hash_packet(id); 614 615 r = uma_zalloc(ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO); 616 if (r == NULL) { 617 printf ("ipfw: sorry cannot allocate state\n"); 618 return NULL; 619 } 620 621 /* increase refcount on parent, and set pointer */ 622 if (dyn_type == O_LIMIT) { 623 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 624 if ( parent->dyn_type != O_LIMIT_PARENT) 625 panic("invalid parent"); 626 parent->count++; 627 r->parent = parent; 628 rule = parent->rule; 629 } 630 631 r->id = *id; 632 r->expire = time_uptime + V_dyn_syn_lifetime; 633 r->rule = rule; 634 r->dyn_type = dyn_type; 635 r->pcnt = r->bcnt = 0; 636 r->count = 0; 637 638 r->bucket = i; 639 r->next = V_ipfw_dyn_v[i]; 640 V_ipfw_dyn_v[i] = r; 641 V_dyn_count++; 642 DEB({ 643 struct in_addr da; 644 #ifdef INET6 645 char src[INET6_ADDRSTRLEN]; 646 char dst[INET6_ADDRSTRLEN]; 647 #else 648 char src[INET_ADDRSTRLEN]; 649 char dst[INET_ADDRSTRLEN]; 650 #endif 651 652 #ifdef INET6 653 if (IS_IP6_FLOW_ID(&(r->id))) { 654 ip6_sprintf(src, &r->id.src_ip6); 655 ip6_sprintf(dst, &r->id.dst_ip6); 656 } else 657 #endif 658 { 659 da.s_addr = htonl(r->id.src_ip); 660 inet_ntop(AF_INET, &da, src, sizeof(src)); 661 da.s_addr = htonl(r->id.dst_ip); 662 inet_ntop(AF_INET, &da, dst, sizeof(dst)); 663 } 664 printf("ipfw: add dyn entry ty %d %s %d -> %s %d, total %d\n", 665 dyn_type, src, r->id.src_port, dst, r->id.dst_port, 666 V_dyn_count); 667 }) 668 return r; 669 } 670 671 /** 672 * lookup dynamic parent rule using pkt and rule as search keys. 673 * If the lookup fails, then install one. 674 */ 675 static ipfw_dyn_rule * 676 lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 677 { 678 ipfw_dyn_rule *q; 679 int i; 680 681 IPFW_DYN_LOCK_ASSERT(); 682 683 if (V_ipfw_dyn_v) { 684 int is_v6 = IS_IP6_FLOW_ID(pkt); 685 i = hash_packet( pkt ); 686 for (q = V_ipfw_dyn_v[i] ; q != NULL ; q=q->next) 687 if (q->dyn_type == O_LIMIT_PARENT && 688 rule== q->rule && 689 pkt->proto == q->id.proto && 690 pkt->src_port == q->id.src_port && 691 pkt->dst_port == q->id.dst_port && 692 ( 693 (is_v6 && 694 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6), 695 &(q->id.src_ip6)) && 696 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6), 697 &(q->id.dst_ip6))) || 698 (!is_v6 && 699 pkt->src_ip == q->id.src_ip && 700 pkt->dst_ip == q->id.dst_ip) 701 ) 702 ) { 703 q->expire = time_uptime + V_dyn_short_lifetime; 704 DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);) 705 return q; 706 } 707 } 708 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 709 } 710 711 /** 712 * Install dynamic state for rule type cmd->o.opcode 713 * 714 * Returns 1 (failure) if state is not installed because of errors or because 715 * session limitations are enforced. 716 */ 717 int 718 ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 719 struct ip_fw_args *args, uint32_t tablearg) 720 { 721 static int last_log; 722 ipfw_dyn_rule *q; 723 struct in_addr da; 724 #ifdef INET6 725 char src[INET6_ADDRSTRLEN + 2], dst[INET6_ADDRSTRLEN + 2]; 726 #else 727 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN]; 728 #endif 729 730 src[0] = '\0'; 731 dst[0] = '\0'; 732 733 IPFW_DYN_LOCK(); 734 735 DEB( 736 #ifdef INET6 737 if (IS_IP6_FLOW_ID(&(args->f_id))) { 738 ip6_sprintf(src, &args->f_id.src_ip6); 739 ip6_sprintf(dst, &args->f_id.dst_ip6); 740 } else 741 #endif 742 { 743 da.s_addr = htonl(args->f_id.src_ip); 744 inet_ntop(AF_INET, &da, src, sizeof(src)); 745 da.s_addr = htonl(args->f_id.dst_ip); 746 inet_ntop(AF_INET, &da, dst, sizeof(dst)); 747 } 748 printf("ipfw: %s: type %d %s %u -> %s %u\n", 749 __func__, cmd->o.opcode, src, args->f_id.src_port, 750 dst, args->f_id.dst_port); 751 src[0] = '\0'; 752 dst[0] = '\0'; 753 ) 754 755 q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL); 756 757 if (q != NULL) { /* should never occur */ 758 DEB( 759 if (last_log != time_uptime) { 760 last_log = time_uptime; 761 printf("ipfw: %s: entry already present, done\n", 762 __func__); 763 }) 764 IPFW_DYN_UNLOCK(); 765 return (0); 766 } 767 768 if (V_dyn_count >= V_dyn_max) 769 /* Run out of slots, try to remove any expired rule. */ 770 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 771 772 if (V_dyn_count >= V_dyn_max) { 773 if (last_log != time_uptime) { 774 last_log = time_uptime; 775 printf("ipfw: %s: Too many dynamic rules\n", __func__); 776 } 777 IPFW_DYN_UNLOCK(); 778 return (1); /* cannot install, notify caller */ 779 } 780 781 switch (cmd->o.opcode) { 782 case O_KEEP_STATE: /* bidir rule */ 783 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 784 break; 785 786 case O_LIMIT: { /* limit number of sessions */ 787 struct ipfw_flow_id id; 788 ipfw_dyn_rule *parent; 789 uint32_t conn_limit; 790 uint16_t limit_mask = cmd->limit_mask; 791 792 conn_limit = (cmd->conn_limit == IP_FW_TABLEARG) ? 793 tablearg : cmd->conn_limit; 794 795 DEB( 796 if (cmd->conn_limit == IP_FW_TABLEARG) 797 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u " 798 "(tablearg)\n", __func__, conn_limit); 799 else 800 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n", 801 __func__, conn_limit); 802 ) 803 804 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0; 805 id.proto = args->f_id.proto; 806 id.addr_type = args->f_id.addr_type; 807 id.fib = M_GETFIB(args->m); 808 809 if (IS_IP6_FLOW_ID (&(args->f_id))) { 810 if (limit_mask & DYN_SRC_ADDR) 811 id.src_ip6 = args->f_id.src_ip6; 812 if (limit_mask & DYN_DST_ADDR) 813 id.dst_ip6 = args->f_id.dst_ip6; 814 } else { 815 if (limit_mask & DYN_SRC_ADDR) 816 id.src_ip = args->f_id.src_ip; 817 if (limit_mask & DYN_DST_ADDR) 818 id.dst_ip = args->f_id.dst_ip; 819 } 820 if (limit_mask & DYN_SRC_PORT) 821 id.src_port = args->f_id.src_port; 822 if (limit_mask & DYN_DST_PORT) 823 id.dst_port = args->f_id.dst_port; 824 if ((parent = lookup_dyn_parent(&id, rule)) == NULL) { 825 printf("ipfw: %s: add parent failed\n", __func__); 826 IPFW_DYN_UNLOCK(); 827 return (1); 828 } 829 830 if (parent->count >= conn_limit) { 831 /* See if we can remove some expired rule. */ 832 remove_dyn_rule(rule, parent); 833 if (parent->count >= conn_limit) { 834 if (V_fw_verbose && last_log != time_uptime) { 835 last_log = time_uptime; 836 #ifdef INET6 837 /* 838 * XXX IPv6 flows are not 839 * supported yet. 840 */ 841 if (IS_IP6_FLOW_ID(&(args->f_id))) { 842 char ip6buf[INET6_ADDRSTRLEN]; 843 snprintf(src, sizeof(src), 844 "[%s]", ip6_sprintf(ip6buf, 845 &args->f_id.src_ip6)); 846 snprintf(dst, sizeof(dst), 847 "[%s]", ip6_sprintf(ip6buf, 848 &args->f_id.dst_ip6)); 849 } else 850 #endif 851 { 852 da.s_addr = 853 htonl(args->f_id.src_ip); 854 inet_ntop(AF_INET, &da, src, 855 sizeof(src)); 856 da.s_addr = 857 htonl(args->f_id.dst_ip); 858 inet_ntop(AF_INET, &da, dst, 859 sizeof(dst)); 860 } 861 log(LOG_SECURITY | LOG_DEBUG, 862 "ipfw: %d %s %s:%u -> %s:%u, %s\n", 863 parent->rule->rulenum, 864 "drop session", 865 src, (args->f_id.src_port), 866 dst, (args->f_id.dst_port), 867 "too many entries"); 868 } 869 IPFW_DYN_UNLOCK(); 870 return (1); 871 } 872 } 873 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 874 break; 875 } 876 default: 877 printf("ipfw: %s: unknown dynamic rule type %u\n", 878 __func__, cmd->o.opcode); 879 IPFW_DYN_UNLOCK(); 880 return (1); 881 } 882 883 /* XXX just set lifetime */ 884 lookup_dyn_rule_locked(&args->f_id, NULL, NULL); 885 886 IPFW_DYN_UNLOCK(); 887 return (0); 888 } 889 890 /* 891 * Generate a TCP packet, containing either a RST or a keepalive. 892 * When flags & TH_RST, we are sending a RST packet, because of a 893 * "reset" action matched the packet. 894 * Otherwise we are sending a keepalive, and flags & TH_ 895 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required 896 * so that MAC can label the reply appropriately. 897 */ 898 struct mbuf * 899 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq, 900 u_int32_t ack, int flags) 901 { 902 struct mbuf *m = NULL; /* stupid compiler */ 903 int len, dir; 904 struct ip *h = NULL; /* stupid compiler */ 905 #ifdef INET6 906 struct ip6_hdr *h6 = NULL; 907 #endif 908 struct tcphdr *th = NULL; 909 910 MGETHDR(m, M_DONTWAIT, MT_DATA); 911 if (m == NULL) 912 return (NULL); 913 914 M_SETFIB(m, id->fib); 915 #ifdef MAC 916 if (replyto != NULL) 917 mac_netinet_firewall_reply(replyto, m); 918 else 919 mac_netinet_firewall_send(m); 920 #else 921 (void)replyto; /* don't warn about unused arg */ 922 #endif 923 924 switch (id->addr_type) { 925 case 4: 926 len = sizeof(struct ip) + sizeof(struct tcphdr); 927 break; 928 #ifdef INET6 929 case 6: 930 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 931 break; 932 #endif 933 default: 934 /* XXX: log me?!? */ 935 FREE_PKT(m); 936 return (NULL); 937 } 938 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN); 939 940 m->m_data += max_linkhdr; 941 m->m_flags |= M_SKIP_FIREWALL; 942 m->m_pkthdr.len = m->m_len = len; 943 m->m_pkthdr.rcvif = NULL; 944 bzero(m->m_data, len); 945 946 switch (id->addr_type) { 947 case 4: 948 h = mtod(m, struct ip *); 949 950 /* prepare for checksum */ 951 h->ip_p = IPPROTO_TCP; 952 h->ip_len = htons(sizeof(struct tcphdr)); 953 if (dir) { 954 h->ip_src.s_addr = htonl(id->src_ip); 955 h->ip_dst.s_addr = htonl(id->dst_ip); 956 } else { 957 h->ip_src.s_addr = htonl(id->dst_ip); 958 h->ip_dst.s_addr = htonl(id->src_ip); 959 } 960 961 th = (struct tcphdr *)(h + 1); 962 break; 963 #ifdef INET6 964 case 6: 965 h6 = mtod(m, struct ip6_hdr *); 966 967 /* prepare for checksum */ 968 h6->ip6_nxt = IPPROTO_TCP; 969 h6->ip6_plen = htons(sizeof(struct tcphdr)); 970 if (dir) { 971 h6->ip6_src = id->src_ip6; 972 h6->ip6_dst = id->dst_ip6; 973 } else { 974 h6->ip6_src = id->dst_ip6; 975 h6->ip6_dst = id->src_ip6; 976 } 977 978 th = (struct tcphdr *)(h6 + 1); 979 break; 980 #endif 981 } 982 983 if (dir) { 984 th->th_sport = htons(id->src_port); 985 th->th_dport = htons(id->dst_port); 986 } else { 987 th->th_sport = htons(id->dst_port); 988 th->th_dport = htons(id->src_port); 989 } 990 th->th_off = sizeof(struct tcphdr) >> 2; 991 992 if (flags & TH_RST) { 993 if (flags & TH_ACK) { 994 th->th_seq = htonl(ack); 995 th->th_flags = TH_RST; 996 } else { 997 if (flags & TH_SYN) 998 seq++; 999 th->th_ack = htonl(seq); 1000 th->th_flags = TH_RST | TH_ACK; 1001 } 1002 } else { 1003 /* 1004 * Keepalive - use caller provided sequence numbers 1005 */ 1006 th->th_seq = htonl(seq); 1007 th->th_ack = htonl(ack); 1008 th->th_flags = TH_ACK; 1009 } 1010 1011 switch (id->addr_type) { 1012 case 4: 1013 th->th_sum = in_cksum(m, len); 1014 1015 /* finish the ip header */ 1016 h->ip_v = 4; 1017 h->ip_hl = sizeof(*h) >> 2; 1018 h->ip_tos = IPTOS_LOWDELAY; 1019 h->ip_off = 0; 1020 /* ip_len must be in host format for ip_output */ 1021 h->ip_len = len; 1022 h->ip_ttl = V_ip_defttl; 1023 h->ip_sum = 0; 1024 break; 1025 #ifdef INET6 1026 case 6: 1027 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6), 1028 sizeof(struct tcphdr)); 1029 1030 /* finish the ip6 header */ 1031 h6->ip6_vfc |= IPV6_VERSION; 1032 h6->ip6_hlim = IPV6_DEFHLIM; 1033 break; 1034 #endif 1035 } 1036 1037 return (m); 1038 } 1039 1040 /* 1041 * This procedure is only used to handle keepalives. It is invoked 1042 * every dyn_keepalive_period 1043 */ 1044 static void 1045 ipfw_tick(void * vnetx) 1046 { 1047 struct mbuf *m0, *m, *mnext, **mtailp; 1048 #ifdef INET6 1049 struct mbuf *m6, **m6_tailp; 1050 #endif 1051 int i; 1052 ipfw_dyn_rule *q; 1053 #ifdef VIMAGE 1054 struct vnet *vp = vnetx; 1055 #endif 1056 1057 CURVNET_SET(vp); 1058 if (V_dyn_keepalive == 0 || V_ipfw_dyn_v == NULL || V_dyn_count == 0) 1059 goto done; 1060 1061 /* 1062 * We make a chain of packets to go out here -- not deferring 1063 * until after we drop the IPFW dynamic rule lock would result 1064 * in a lock order reversal with the normal packet input -> ipfw 1065 * call stack. 1066 */ 1067 m0 = NULL; 1068 mtailp = &m0; 1069 #ifdef INET6 1070 m6 = NULL; 1071 m6_tailp = &m6; 1072 #endif 1073 IPFW_DYN_LOCK(); 1074 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 1075 for (q = V_ipfw_dyn_v[i] ; q ; q = q->next ) { 1076 if (q->dyn_type == O_LIMIT_PARENT) 1077 continue; 1078 if (q->id.proto != IPPROTO_TCP) 1079 continue; 1080 if ( (q->state & BOTH_SYN) != BOTH_SYN) 1081 continue; 1082 if (TIME_LEQ(time_uptime + V_dyn_keepalive_interval, 1083 q->expire)) 1084 continue; /* too early */ 1085 if (TIME_LEQ(q->expire, time_uptime)) 1086 continue; /* too late, rule expired */ 1087 1088 m = (q->state & ACK_REV) ? NULL : 1089 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, 1090 q->ack_fwd, TH_SYN); 1091 mnext = (q->state & ACK_FWD) ? NULL : 1092 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, 1093 q->ack_rev, 0); 1094 1095 switch (q->id.addr_type) { 1096 case 4: 1097 if (m != NULL) { 1098 *mtailp = m; 1099 mtailp = &(*mtailp)->m_nextpkt; 1100 } 1101 if (mnext != NULL) { 1102 *mtailp = mnext; 1103 mtailp = &(*mtailp)->m_nextpkt; 1104 } 1105 break; 1106 #ifdef INET6 1107 case 6: 1108 if (m != NULL) { 1109 *m6_tailp = m; 1110 m6_tailp = &(*m6_tailp)->m_nextpkt; 1111 } 1112 if (mnext != NULL) { 1113 *m6_tailp = mnext; 1114 m6_tailp = &(*m6_tailp)->m_nextpkt; 1115 } 1116 break; 1117 #endif 1118 } 1119 } 1120 } 1121 IPFW_DYN_UNLOCK(); 1122 for (m = m0; m != NULL; m = mnext) { 1123 mnext = m->m_nextpkt; 1124 m->m_nextpkt = NULL; 1125 ip_output(m, NULL, NULL, 0, NULL, NULL); 1126 } 1127 #ifdef INET6 1128 for (m = m6; m != NULL; m = mnext) { 1129 mnext = m->m_nextpkt; 1130 m->m_nextpkt = NULL; 1131 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL); 1132 } 1133 #endif 1134 done: 1135 callout_reset_on(&V_ipfw_timeout, V_dyn_keepalive_period * hz, 1136 ipfw_tick, vnetx, 0); 1137 CURVNET_RESTORE(); 1138 } 1139 1140 void 1141 ipfw_dyn_attach(void) 1142 { 1143 ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule", 1144 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL, 1145 UMA_ALIGN_PTR, 0); 1146 1147 IPFW_DYN_LOCK_INIT(); 1148 } 1149 1150 void 1151 ipfw_dyn_detach(void) 1152 { 1153 uma_zdestroy(ipfw_dyn_rule_zone); 1154 IPFW_DYN_LOCK_DESTROY(); 1155 } 1156 1157 void 1158 ipfw_dyn_init(void) 1159 { 1160 V_ipfw_dyn_v = NULL; 1161 V_dyn_buckets = 256; /* must be power of 2 */ 1162 V_curr_dyn_buckets = 256; /* must be power of 2 */ 1163 1164 V_dyn_ack_lifetime = 300; 1165 V_dyn_syn_lifetime = 20; 1166 V_dyn_fin_lifetime = 1; 1167 V_dyn_rst_lifetime = 1; 1168 V_dyn_udp_lifetime = 10; 1169 V_dyn_short_lifetime = 5; 1170 1171 V_dyn_keepalive_interval = 20; 1172 V_dyn_keepalive_period = 5; 1173 V_dyn_keepalive = 1; /* do send keepalives */ 1174 1175 V_dyn_max = 4096; /* max # of dynamic rules */ 1176 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE); 1177 callout_reset_on(&V_ipfw_timeout, hz, ipfw_tick, curvnet, 0); 1178 } 1179 1180 void 1181 ipfw_dyn_uninit(int pass) 1182 { 1183 if (pass == 0) 1184 callout_drain(&V_ipfw_timeout); 1185 else { 1186 if (V_ipfw_dyn_v != NULL) 1187 free(V_ipfw_dyn_v, M_IPFW); 1188 } 1189 } 1190 1191 int 1192 ipfw_dyn_len(void) 1193 { 1194 return (V_ipfw_dyn_v == NULL) ? 0 : 1195 (V_dyn_count * sizeof(ipfw_dyn_rule)); 1196 } 1197 1198 void 1199 ipfw_get_dynamic(char **pbp, const char *ep) 1200 { 1201 ipfw_dyn_rule *p, *last = NULL; 1202 char *bp; 1203 int i; 1204 1205 if (V_ipfw_dyn_v == NULL) 1206 return; 1207 bp = *pbp; 1208 1209 IPFW_DYN_LOCK(); 1210 for (i = 0 ; i < V_curr_dyn_buckets; i++) 1211 for (p = V_ipfw_dyn_v[i] ; p != NULL; p = p->next) { 1212 if (bp + sizeof *p <= ep) { 1213 ipfw_dyn_rule *dst = 1214 (ipfw_dyn_rule *)bp; 1215 bcopy(p, dst, sizeof *p); 1216 bcopy(&(p->rule->rulenum), &(dst->rule), 1217 sizeof(p->rule->rulenum)); 1218 /* 1219 * store set number into high word of 1220 * dst->rule pointer. 1221 */ 1222 bcopy(&(p->rule->set), 1223 (char *)&dst->rule + 1224 sizeof(p->rule->rulenum), 1225 sizeof(p->rule->set)); 1226 /* 1227 * store a non-null value in "next". 1228 * The userland code will interpret a 1229 * NULL here as a marker 1230 * for the last dynamic rule. 1231 */ 1232 bcopy(&dst, &dst->next, sizeof(dst)); 1233 last = dst; 1234 dst->expire = 1235 TIME_LEQ(dst->expire, time_uptime) ? 1236 0 : dst->expire - time_uptime ; 1237 bp += sizeof(ipfw_dyn_rule); 1238 } 1239 } 1240 IPFW_DYN_UNLOCK(); 1241 if (last != NULL) /* mark last dynamic rule */ 1242 bzero(&last->next, sizeof(last)); 1243 *pbp = bp; 1244 } 1245 /* end of file */ 1246