ip_fw_dynamic.c revision 236692
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: stable/9/sys/netinet/ipfw/ip_fw_dynamic.c 236692 2012-06-06 18:00:19Z oleg $"); 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/ipfw/ip_fw_private.h> 61#include <netinet/tcp_var.h> 62#include <netinet/udp.h> 63 64#include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */ 65#ifdef INET6 66#include <netinet6/in6_var.h> 67#include <netinet6/ip6_var.h> 68#endif 69 70#include <machine/in_cksum.h> /* XXX for in_cksum */ 71 72#ifdef MAC 73#include <security/mac/mac_framework.h> 74#endif 75 76/* 77 * Description of dynamic rules. 78 * 79 * Dynamic rules are stored in lists accessed through a hash table 80 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 81 * be modified through the sysctl variable dyn_buckets which is 82 * updated when the table becomes empty. 83 * 84 * XXX currently there is only one list, ipfw_dyn. 85 * 86 * When a packet is received, its address fields are first masked 87 * with the mask defined for the rule, then hashed, then matched 88 * against the entries in the corresponding list. 89 * Dynamic rules can be used for different purposes: 90 * + stateful rules; 91 * + enforcing limits on the number of sessions; 92 * + in-kernel NAT (not implemented yet) 93 * 94 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 95 * measured in seconds and depending on the flags. 96 * 97 * The total number of dynamic rules is stored in dyn_count. 98 * The max number of dynamic rules is dyn_max. When we reach 99 * the maximum number of rules we do not create anymore. This is 100 * done to avoid consuming too much memory, but also too much 101 * time when searching on each packet (ideally, we should try instead 102 * to put a limit on the length of the list on each bucket...). 103 * 104 * Each dynamic rule holds a pointer to the parent ipfw rule so 105 * we know what action to perform. Dynamic rules are removed when 106 * the parent rule is deleted. XXX we should make them survive. 107 * 108 * There are some limitations with dynamic rules -- we do not 109 * obey the 'randomized match', and we do not do multiple 110 * passes through the firewall. XXX check the latter!!! 111 */ 112 113/* 114 * Static variables followed by global ones 115 */ 116static VNET_DEFINE(ipfw_dyn_rule **, ipfw_dyn_v); 117static VNET_DEFINE(u_int32_t, dyn_buckets); 118static VNET_DEFINE(u_int32_t, curr_dyn_buckets); 119static VNET_DEFINE(struct callout, ipfw_timeout); 120#define V_ipfw_dyn_v VNET(ipfw_dyn_v) 121#define V_dyn_buckets VNET(dyn_buckets) 122#define V_curr_dyn_buckets VNET(curr_dyn_buckets) 123#define V_ipfw_timeout VNET(ipfw_timeout) 124 125static uma_zone_t ipfw_dyn_rule_zone; 126#ifndef __FreeBSD__ 127DEFINE_SPINLOCK(ipfw_dyn_mtx); 128#else 129static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */ 130#endif 131 132#define IPFW_DYN_LOCK_INIT() \ 133 mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF) 134#define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx) 135#define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx) 136#define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx) 137#define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED) 138 139void 140ipfw_dyn_unlock(void) 141{ 142 IPFW_DYN_UNLOCK(); 143} 144 145/* 146 * Timeouts for various events in handing dynamic rules. 147 */ 148static VNET_DEFINE(u_int32_t, dyn_ack_lifetime); 149static VNET_DEFINE(u_int32_t, dyn_syn_lifetime); 150static VNET_DEFINE(u_int32_t, dyn_fin_lifetime); 151static VNET_DEFINE(u_int32_t, dyn_rst_lifetime); 152static VNET_DEFINE(u_int32_t, dyn_udp_lifetime); 153static VNET_DEFINE(u_int32_t, dyn_short_lifetime); 154 155#define V_dyn_ack_lifetime VNET(dyn_ack_lifetime) 156#define V_dyn_syn_lifetime VNET(dyn_syn_lifetime) 157#define V_dyn_fin_lifetime VNET(dyn_fin_lifetime) 158#define V_dyn_rst_lifetime VNET(dyn_rst_lifetime) 159#define V_dyn_udp_lifetime VNET(dyn_udp_lifetime) 160#define V_dyn_short_lifetime VNET(dyn_short_lifetime) 161 162/* 163 * Keepalives are sent if dyn_keepalive is set. They are sent every 164 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 165 * seconds of lifetime of a rule. 166 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 167 * than dyn_keepalive_period. 168 */ 169 170static VNET_DEFINE(u_int32_t, dyn_keepalive_interval); 171static VNET_DEFINE(u_int32_t, dyn_keepalive_period); 172static VNET_DEFINE(u_int32_t, dyn_keepalive); 173 174#define V_dyn_keepalive_interval VNET(dyn_keepalive_interval) 175#define V_dyn_keepalive_period VNET(dyn_keepalive_period) 176#define V_dyn_keepalive VNET(dyn_keepalive) 177 178static VNET_DEFINE(u_int32_t, dyn_count); /* # of dynamic rules */ 179static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */ 180 181#define V_dyn_count VNET(dyn_count) 182#define V_dyn_max VNET(dyn_max) 183 184#ifdef SYSCTL_NODE 185 186SYSBEGIN(f2) 187 188SYSCTL_DECL(_net_inet_ip_fw); 189SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, 190 CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0, 191 "Number of dyn. buckets"); 192SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, 193 CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0, 194 "Current Number of dyn. buckets"); 195SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_count, 196 CTLFLAG_RD, &VNET_NAME(dyn_count), 0, 197 "Number of dyn. rules"); 198SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_max, 199 CTLFLAG_RW, &VNET_NAME(dyn_max), 0, 200 "Max number of dyn. rules"); 201SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, 202 CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0, 203 "Lifetime of dyn. rules for acks"); 204SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, 205 CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0, 206 "Lifetime of dyn. rules for syn"); 207SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, 208 CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0, 209 "Lifetime of dyn. rules for fin"); 210SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, 211 CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0, 212 "Lifetime of dyn. rules for rst"); 213SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, 214 CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0, 215 "Lifetime of dyn. rules for UDP"); 216SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, 217 CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0, 218 "Lifetime of dyn. rules for other situations"); 219SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, 220 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0, 221 "Enable keepalives for dyn. rules"); 222 223SYSEND 224 225#endif /* SYSCTL_NODE */ 226 227 228static __inline int 229hash_packet6(struct ipfw_flow_id *id) 230{ 231 u_int32_t i; 232 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^ 233 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^ 234 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^ 235 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^ 236 (id->dst_port) ^ (id->src_port); 237 return i; 238} 239 240/* 241 * IMPORTANT: the hash function for dynamic rules must be commutative 242 * in source and destination (ip,port), because rules are bidirectional 243 * and we want to find both in the same bucket. 244 */ 245static __inline int 246hash_packet(struct ipfw_flow_id *id) 247{ 248 u_int32_t i; 249 250#ifdef INET6 251 if (IS_IP6_FLOW_ID(id)) 252 i = hash_packet6(id); 253 else 254#endif /* INET6 */ 255 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); 256 i &= (V_curr_dyn_buckets - 1); 257 return i; 258} 259 260static __inline void 261unlink_dyn_rule_print(struct ipfw_flow_id *id) 262{ 263 struct in_addr da; 264#ifdef INET6 265 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN]; 266#else 267 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN]; 268#endif 269 270#ifdef INET6 271 if (IS_IP6_FLOW_ID(id)) { 272 ip6_sprintf(src, &id->src_ip6); 273 ip6_sprintf(dst, &id->dst_ip6); 274 } else 275#endif 276 { 277 da.s_addr = htonl(id->src_ip); 278 inet_ntoa_r(da, src); 279 da.s_addr = htonl(id->dst_ip); 280 inet_ntoa_r(da, dst); 281 } 282 printf("ipfw: unlink entry %s %d -> %s %d, %d left\n", 283 src, id->src_port, dst, id->dst_port, V_dyn_count - 1); 284} 285 286/** 287 * unlink a dynamic rule from a chain. prev is a pointer to 288 * the previous one, q is a pointer to the rule to delete, 289 * head is a pointer to the head of the queue. 290 * Modifies q and potentially also head. 291 */ 292#define UNLINK_DYN_RULE(prev, head, q) { \ 293 ipfw_dyn_rule *old_q = q; \ 294 \ 295 /* remove a refcount to the parent */ \ 296 if (q->dyn_type == O_LIMIT) \ 297 q->parent->count--; \ 298 DEB(unlink_dyn_rule_print(&q->id);) \ 299 if (prev != NULL) \ 300 prev->next = q = q->next; \ 301 else \ 302 head = q = q->next; \ 303 V_dyn_count--; \ 304 uma_zfree(ipfw_dyn_rule_zone, old_q); } 305 306#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 307 308/** 309 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. 310 * 311 * If keep_me == NULL, rules are deleted even if not expired, 312 * otherwise only expired rules are removed. 313 * 314 * The value of the second parameter is also used to point to identify 315 * a rule we absolutely do not want to remove (e.g. because we are 316 * holding a reference to it -- this is the case with O_LIMIT_PARENT 317 * rules). The pointer is only used for comparison, so any non-null 318 * value will do. 319 */ 320static void 321remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) 322{ 323 static u_int32_t last_remove = 0; 324 325#define FORCE (keep_me == NULL) 326 327 ipfw_dyn_rule *prev, *q; 328 int i, pass = 0, max_pass = 0; 329 330 IPFW_DYN_LOCK_ASSERT(); 331 332 if (V_ipfw_dyn_v == NULL || V_dyn_count == 0) 333 return; 334 /* do not expire more than once per second, it is useless */ 335 if (!FORCE && last_remove == time_uptime) 336 return; 337 last_remove = time_uptime; 338 339 /* 340 * because O_LIMIT refer to parent rules, during the first pass only 341 * remove child and mark any pending LIMIT_PARENT, and remove 342 * them in a second pass. 343 */ 344next_pass: 345 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 346 for (prev=NULL, q = V_ipfw_dyn_v[i] ; q ; ) { 347 /* 348 * Logic can become complex here, so we split tests. 349 */ 350 if (q == keep_me) 351 goto next; 352 if (rule != NULL && rule != q->rule) 353 goto next; /* not the one we are looking for */ 354 if (q->dyn_type == O_LIMIT_PARENT) { 355 /* 356 * handle parent in the second pass, 357 * record we need one. 358 */ 359 max_pass = 1; 360 if (pass == 0) 361 goto next; 362 if (FORCE && q->count != 0 ) { 363 /* XXX should not happen! */ 364 printf("ipfw: OUCH! cannot remove rule," 365 " count %d\n", q->count); 366 } 367 } else { 368 if (!FORCE && 369 !TIME_LEQ( q->expire, time_uptime )) 370 goto next; 371 } 372 if (q->dyn_type != O_LIMIT_PARENT || !q->count) { 373 UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q); 374 continue; 375 } 376next: 377 prev=q; 378 q=q->next; 379 } 380 } 381 if (pass++ < max_pass) 382 goto next_pass; 383} 384 385void 386ipfw_remove_dyn_children(struct ip_fw *rule) 387{ 388 IPFW_DYN_LOCK(); 389 remove_dyn_rule(rule, NULL /* force removal */); 390 IPFW_DYN_UNLOCK(); 391} 392 393/* 394 * Lookup a dynamic rule, locked version. 395 */ 396static ipfw_dyn_rule * 397lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction, 398 struct tcphdr *tcp) 399{ 400 /* 401 * Stateful ipfw extensions. 402 * Lookup into dynamic session queue. 403 */ 404#define MATCH_REVERSE 0 405#define MATCH_FORWARD 1 406#define MATCH_NONE 2 407#define MATCH_UNKNOWN 3 408 int i, dir = MATCH_NONE; 409 ipfw_dyn_rule *prev, *q = NULL; 410 411 IPFW_DYN_LOCK_ASSERT(); 412 413 if (V_ipfw_dyn_v == NULL) 414 goto done; /* not found */ 415 i = hash_packet(pkt); 416 for (prev = NULL, q = V_ipfw_dyn_v[i]; q != NULL;) { 417 if (q->dyn_type == O_LIMIT_PARENT && q->count) 418 goto next; 419 if (TIME_LEQ(q->expire, time_uptime)) { /* expire entry */ 420 UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q); 421 continue; 422 } 423 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT) 424 goto next; 425 426 if (IS_IP6_FLOW_ID(pkt)) { 427 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) && 428 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) && 429 pkt->src_port == q->id.src_port && 430 pkt->dst_port == q->id.dst_port) { 431 dir = MATCH_FORWARD; 432 break; 433 } 434 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) && 435 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) && 436 pkt->src_port == q->id.dst_port && 437 pkt->dst_port == q->id.src_port) { 438 dir = MATCH_REVERSE; 439 break; 440 } 441 } else { 442 if (pkt->src_ip == q->id.src_ip && 443 pkt->dst_ip == q->id.dst_ip && 444 pkt->src_port == q->id.src_port && 445 pkt->dst_port == q->id.dst_port) { 446 dir = MATCH_FORWARD; 447 break; 448 } 449 if (pkt->src_ip == q->id.dst_ip && 450 pkt->dst_ip == q->id.src_ip && 451 pkt->src_port == q->id.dst_port && 452 pkt->dst_port == q->id.src_port) { 453 dir = MATCH_REVERSE; 454 break; 455 } 456 } 457next: 458 prev = q; 459 q = q->next; 460 } 461 if (q == NULL) 462 goto done; /* q = NULL, not found */ 463 464 if (prev != NULL) { /* found and not in front */ 465 prev->next = q->next; 466 q->next = V_ipfw_dyn_v[i]; 467 V_ipfw_dyn_v[i] = q; 468 } 469 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ 470 uint32_t ack; 471 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST); 472 473#define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 474#define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 475#define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8)) 476#define ACK_FWD 0x10000 /* fwd ack seen */ 477#define ACK_REV 0x20000 /* rev ack seen */ 478 479 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8); 480 switch (q->state & TCP_FLAGS) { 481 case TH_SYN: /* opening */ 482 q->expire = time_uptime + V_dyn_syn_lifetime; 483 break; 484 485 case BOTH_SYN: /* move to established */ 486 case BOTH_SYN | TH_FIN: /* one side tries to close */ 487 case BOTH_SYN | (TH_FIN << 8): 488#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 489 if (tcp == NULL) 490 break; 491 492 ack = ntohl(tcp->th_ack); 493 if (dir == MATCH_FORWARD) { 494 if (q->ack_fwd == 0 || 495 _SEQ_GE(ack, q->ack_fwd)) { 496 q->ack_fwd = ack; 497 q->state |= ACK_FWD; 498 } 499 } else { 500 if (q->ack_rev == 0 || 501 _SEQ_GE(ack, q->ack_rev)) { 502 q->ack_rev = ack; 503 q->state |= ACK_REV; 504 } 505 } 506 if ((q->state & (ACK_FWD | ACK_REV)) == 507 (ACK_FWD | ACK_REV)) { 508 q->expire = time_uptime + V_dyn_ack_lifetime; 509 q->state &= ~(ACK_FWD | ACK_REV); 510 } 511 break; 512 513 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 514 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period) 515 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1; 516 q->expire = time_uptime + V_dyn_fin_lifetime; 517 break; 518 519 default: 520#if 0 521 /* 522 * reset or some invalid combination, but can also 523 * occur if we use keep-state the wrong way. 524 */ 525 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 526 printf("invalid state: 0x%x\n", q->state); 527#endif 528 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period) 529 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1; 530 q->expire = time_uptime + V_dyn_rst_lifetime; 531 break; 532 } 533 } else if (pkt->proto == IPPROTO_UDP) { 534 q->expire = time_uptime + V_dyn_udp_lifetime; 535 } else { 536 /* other protocols */ 537 q->expire = time_uptime + V_dyn_short_lifetime; 538 } 539done: 540 if (match_direction != NULL) 541 *match_direction = dir; 542 return (q); 543} 544 545ipfw_dyn_rule * 546ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 547 struct tcphdr *tcp) 548{ 549 ipfw_dyn_rule *q; 550 551 IPFW_DYN_LOCK(); 552 q = lookup_dyn_rule_locked(pkt, match_direction, tcp); 553 if (q == NULL) 554 IPFW_DYN_UNLOCK(); 555 /* NB: return table locked when q is not NULL */ 556 return q; 557} 558 559static void 560realloc_dynamic_table(void) 561{ 562 IPFW_DYN_LOCK_ASSERT(); 563 564 /* 565 * Try reallocation, make sure we have a power of 2 and do 566 * not allow more than 64k entries. In case of overflow, 567 * default to 1024. 568 */ 569 570 if (V_dyn_buckets > 65536) 571 V_dyn_buckets = 1024; 572 if ((V_dyn_buckets & (V_dyn_buckets-1)) != 0) { /* not a power of 2 */ 573 V_dyn_buckets = V_curr_dyn_buckets; /* reset */ 574 return; 575 } 576 V_curr_dyn_buckets = V_dyn_buckets; 577 if (V_ipfw_dyn_v != NULL) 578 free(V_ipfw_dyn_v, M_IPFW); 579 for (;;) { 580 V_ipfw_dyn_v = malloc(V_curr_dyn_buckets * sizeof(ipfw_dyn_rule *), 581 M_IPFW, M_NOWAIT | M_ZERO); 582 if (V_ipfw_dyn_v != NULL || V_curr_dyn_buckets <= 2) 583 break; 584 V_curr_dyn_buckets /= 2; 585 } 586} 587 588/** 589 * Install state of type 'type' for a dynamic session. 590 * The hash table contains two type of rules: 591 * - regular rules (O_KEEP_STATE) 592 * - rules for sessions with limited number of sess per user 593 * (O_LIMIT). When they are created, the parent is 594 * increased by 1, and decreased on delete. In this case, 595 * the third parameter is the parent rule and not the chain. 596 * - "parent" rules for the above (O_LIMIT_PARENT). 597 */ 598static ipfw_dyn_rule * 599add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) 600{ 601 ipfw_dyn_rule *r; 602 int i; 603 604 IPFW_DYN_LOCK_ASSERT(); 605 606 if (V_ipfw_dyn_v == NULL || 607 (V_dyn_count == 0 && V_dyn_buckets != V_curr_dyn_buckets)) { 608 realloc_dynamic_table(); 609 if (V_ipfw_dyn_v == NULL) 610 return NULL; /* failed ! */ 611 } 612 i = hash_packet(id); 613 614 r = uma_zalloc(ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO); 615 if (r == NULL) { 616 printf ("ipfw: sorry cannot allocate state\n"); 617 return NULL; 618 } 619 620 /* increase refcount on parent, and set pointer */ 621 if (dyn_type == O_LIMIT) { 622 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 623 if ( parent->dyn_type != O_LIMIT_PARENT) 624 panic("invalid parent"); 625 parent->count++; 626 r->parent = parent; 627 rule = parent->rule; 628 } 629 630 r->id = *id; 631 r->expire = time_uptime + V_dyn_syn_lifetime; 632 r->rule = rule; 633 r->dyn_type = dyn_type; 634 r->pcnt = r->bcnt = 0; 635 r->count = 0; 636 637 r->bucket = i; 638 r->next = V_ipfw_dyn_v[i]; 639 V_ipfw_dyn_v[i] = r; 640 V_dyn_count++; 641 DEB({ 642 struct in_addr da; 643#ifdef INET6 644 char src[INET6_ADDRSTRLEN]; 645 char dst[INET6_ADDRSTRLEN]; 646#else 647 char src[INET_ADDRSTRLEN]; 648 char dst[INET_ADDRSTRLEN]; 649#endif 650 651#ifdef INET6 652 if (IS_IP6_FLOW_ID(&(r->id))) { 653 ip6_sprintf(src, &r->id.src_ip6); 654 ip6_sprintf(dst, &r->id.dst_ip6); 655 } else 656#endif 657 { 658 da.s_addr = htonl(r->id.src_ip); 659 inet_ntoa_r(da, src); 660 da.s_addr = htonl(r->id.dst_ip); 661 inet_ntoa_r(da, dst); 662 } 663 printf("ipfw: add dyn entry ty %d %s %d -> %s %d, total %d\n", 664 dyn_type, src, r->id.src_port, dst, r->id.dst_port, 665 V_dyn_count); 666 }) 667 return r; 668} 669 670/** 671 * lookup dynamic parent rule using pkt and rule as search keys. 672 * If the lookup fails, then install one. 673 */ 674static ipfw_dyn_rule * 675lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) 676{ 677 ipfw_dyn_rule *q; 678 int i; 679 680 IPFW_DYN_LOCK_ASSERT(); 681 682 if (V_ipfw_dyn_v) { 683 int is_v6 = IS_IP6_FLOW_ID(pkt); 684 i = hash_packet( pkt ); 685 for (q = V_ipfw_dyn_v[i] ; q != NULL ; q=q->next) 686 if (q->dyn_type == O_LIMIT_PARENT && 687 rule== q->rule && 688 pkt->proto == q->id.proto && 689 pkt->src_port == q->id.src_port && 690 pkt->dst_port == q->id.dst_port && 691 ( 692 (is_v6 && 693 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6), 694 &(q->id.src_ip6)) && 695 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6), 696 &(q->id.dst_ip6))) || 697 (!is_v6 && 698 pkt->src_ip == q->id.src_ip && 699 pkt->dst_ip == q->id.dst_ip) 700 ) 701 ) { 702 q->expire = time_uptime + V_dyn_short_lifetime; 703 DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);) 704 return q; 705 } 706 } 707 return add_dyn_rule(pkt, O_LIMIT_PARENT, rule); 708} 709 710/** 711 * Install dynamic state for rule type cmd->o.opcode 712 * 713 * Returns 1 (failure) if state is not installed because of errors or because 714 * session limitations are enforced. 715 */ 716int 717ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd, 718 struct ip_fw_args *args, uint32_t tablearg) 719{ 720 static int last_log; 721 ipfw_dyn_rule *q; 722 struct in_addr da; 723#ifdef INET6 724 char src[INET6_ADDRSTRLEN + 2], dst[INET6_ADDRSTRLEN + 2]; 725#else 726 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN]; 727#endif 728 729 src[0] = '\0'; 730 dst[0] = '\0'; 731 732 IPFW_DYN_LOCK(); 733 734 DEB( 735#ifdef INET6 736 if (IS_IP6_FLOW_ID(&(args->f_id))) { 737 ip6_sprintf(src, &args->f_id.src_ip6); 738 ip6_sprintf(dst, &args->f_id.dst_ip6); 739 } else 740#endif 741 { 742 da.s_addr = htonl(args->f_id.src_ip); 743 inet_ntoa_r(da, src); 744 da.s_addr = htonl(args->f_id.dst_ip); 745 inet_ntoa_r(da, dst); 746 } 747 printf("ipfw: %s: type %d %s %u -> %s %u\n", 748 __func__, cmd->o.opcode, src, args->f_id.src_port, 749 dst, args->f_id.dst_port); 750 src[0] = '\0'; 751 dst[0] = '\0'; 752 ) 753 754 q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL); 755 756 if (q != NULL) { /* should never occur */ 757 DEB( 758 if (last_log != time_uptime) { 759 last_log = time_uptime; 760 printf("ipfw: %s: entry already present, done\n", 761 __func__); 762 }) 763 IPFW_DYN_UNLOCK(); 764 return (0); 765 } 766 767 if (V_dyn_count >= V_dyn_max) 768 /* Run out of slots, try to remove any expired rule. */ 769 remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); 770 771 if (V_dyn_count >= V_dyn_max) { 772 if (last_log != time_uptime) { 773 last_log = time_uptime; 774 printf("ipfw: %s: Too many dynamic rules\n", __func__); 775 } 776 IPFW_DYN_UNLOCK(); 777 return (1); /* cannot install, notify caller */ 778 } 779 780 switch (cmd->o.opcode) { 781 case O_KEEP_STATE: /* bidir rule */ 782 add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); 783 break; 784 785 case O_LIMIT: { /* limit number of sessions */ 786 struct ipfw_flow_id id; 787 ipfw_dyn_rule *parent; 788 uint32_t conn_limit; 789 uint16_t limit_mask = cmd->limit_mask; 790 791 conn_limit = (cmd->conn_limit == IP_FW_TABLEARG) ? 792 tablearg : cmd->conn_limit; 793 794 DEB( 795 if (cmd->conn_limit == IP_FW_TABLEARG) 796 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u " 797 "(tablearg)\n", __func__, conn_limit); 798 else 799 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n", 800 __func__, conn_limit); 801 ) 802 803 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0; 804 id.proto = args->f_id.proto; 805 id.addr_type = args->f_id.addr_type; 806 id.fib = M_GETFIB(args->m); 807 808 if (IS_IP6_FLOW_ID (&(args->f_id))) { 809 if (limit_mask & DYN_SRC_ADDR) 810 id.src_ip6 = args->f_id.src_ip6; 811 if (limit_mask & DYN_DST_ADDR) 812 id.dst_ip6 = args->f_id.dst_ip6; 813 } else { 814 if (limit_mask & DYN_SRC_ADDR) 815 id.src_ip = args->f_id.src_ip; 816 if (limit_mask & DYN_DST_ADDR) 817 id.dst_ip = args->f_id.dst_ip; 818 } 819 if (limit_mask & DYN_SRC_PORT) 820 id.src_port = args->f_id.src_port; 821 if (limit_mask & DYN_DST_PORT) 822 id.dst_port = args->f_id.dst_port; 823 if ((parent = lookup_dyn_parent(&id, rule)) == NULL) { 824 printf("ipfw: %s: add parent failed\n", __func__); 825 IPFW_DYN_UNLOCK(); 826 return (1); 827 } 828 829 if (parent->count >= conn_limit) { 830 /* See if we can remove some expired rule. */ 831 remove_dyn_rule(rule, parent); 832 if (parent->count >= conn_limit) { 833 if (V_fw_verbose && last_log != time_uptime) { 834 last_log = time_uptime; 835#ifdef INET6 836 /* 837 * XXX IPv6 flows are not 838 * supported yet. 839 */ 840 if (IS_IP6_FLOW_ID(&(args->f_id))) { 841 char ip6buf[INET6_ADDRSTRLEN]; 842 snprintf(src, sizeof(src), 843 "[%s]", ip6_sprintf(ip6buf, 844 &args->f_id.src_ip6)); 845 snprintf(dst, sizeof(dst), 846 "[%s]", ip6_sprintf(ip6buf, 847 &args->f_id.dst_ip6)); 848 } else 849#endif 850 { 851 da.s_addr = 852 htonl(args->f_id.src_ip); 853 inet_ntoa_r(da, src); 854 da.s_addr = 855 htonl(args->f_id.dst_ip); 856 inet_ntoa_r(da, dst); 857 } 858 log(LOG_SECURITY | LOG_DEBUG, 859 "ipfw: %d %s %s:%u -> %s:%u, %s\n", 860 parent->rule->rulenum, 861 "drop session", 862 src, (args->f_id.src_port), 863 dst, (args->f_id.dst_port), 864 "too many entries"); 865 } 866 IPFW_DYN_UNLOCK(); 867 return (1); 868 } 869 } 870 add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); 871 break; 872 } 873 default: 874 printf("ipfw: %s: unknown dynamic rule type %u\n", 875 __func__, cmd->o.opcode); 876 IPFW_DYN_UNLOCK(); 877 return (1); 878 } 879 880 /* XXX just set lifetime */ 881 lookup_dyn_rule_locked(&args->f_id, NULL, NULL); 882 883 IPFW_DYN_UNLOCK(); 884 return (0); 885} 886 887/* 888 * Generate a TCP packet, containing either a RST or a keepalive. 889 * When flags & TH_RST, we are sending a RST packet, because of a 890 * "reset" action matched the packet. 891 * Otherwise we are sending a keepalive, and flags & TH_ 892 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required 893 * so that MAC can label the reply appropriately. 894 */ 895struct mbuf * 896ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq, 897 u_int32_t ack, int flags) 898{ 899 struct mbuf *m = NULL; /* stupid compiler */ 900 int len, dir; 901 struct ip *h = NULL; /* stupid compiler */ 902#ifdef INET6 903 struct ip6_hdr *h6 = NULL; 904#endif 905 struct tcphdr *th = NULL; 906 907 MGETHDR(m, M_DONTWAIT, MT_DATA); 908 if (m == NULL) 909 return (NULL); 910 911 M_SETFIB(m, id->fib); 912#ifdef MAC 913 if (replyto != NULL) 914 mac_netinet_firewall_reply(replyto, m); 915 else 916 mac_netinet_firewall_send(m); 917#else 918 (void)replyto; /* don't warn about unused arg */ 919#endif 920 921 switch (id->addr_type) { 922 case 4: 923 len = sizeof(struct ip) + sizeof(struct tcphdr); 924 break; 925#ifdef INET6 926 case 6: 927 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 928 break; 929#endif 930 default: 931 /* XXX: log me?!? */ 932 FREE_PKT(m); 933 return (NULL); 934 } 935 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN); 936 937 m->m_data += max_linkhdr; 938 m->m_flags |= M_SKIP_FIREWALL; 939 m->m_pkthdr.len = m->m_len = len; 940 m->m_pkthdr.rcvif = NULL; 941 bzero(m->m_data, len); 942 943 switch (id->addr_type) { 944 case 4: 945 h = mtod(m, struct ip *); 946 947 /* prepare for checksum */ 948 h->ip_p = IPPROTO_TCP; 949 h->ip_len = htons(sizeof(struct tcphdr)); 950 if (dir) { 951 h->ip_src.s_addr = htonl(id->src_ip); 952 h->ip_dst.s_addr = htonl(id->dst_ip); 953 } else { 954 h->ip_src.s_addr = htonl(id->dst_ip); 955 h->ip_dst.s_addr = htonl(id->src_ip); 956 } 957 958 th = (struct tcphdr *)(h + 1); 959 break; 960#ifdef INET6 961 case 6: 962 h6 = mtod(m, struct ip6_hdr *); 963 964 /* prepare for checksum */ 965 h6->ip6_nxt = IPPROTO_TCP; 966 h6->ip6_plen = htons(sizeof(struct tcphdr)); 967 if (dir) { 968 h6->ip6_src = id->src_ip6; 969 h6->ip6_dst = id->dst_ip6; 970 } else { 971 h6->ip6_src = id->dst_ip6; 972 h6->ip6_dst = id->src_ip6; 973 } 974 975 th = (struct tcphdr *)(h6 + 1); 976 break; 977#endif 978 } 979 980 if (dir) { 981 th->th_sport = htons(id->src_port); 982 th->th_dport = htons(id->dst_port); 983 } else { 984 th->th_sport = htons(id->dst_port); 985 th->th_dport = htons(id->src_port); 986 } 987 th->th_off = sizeof(struct tcphdr) >> 2; 988 989 if (flags & TH_RST) { 990 if (flags & TH_ACK) { 991 th->th_seq = htonl(ack); 992 th->th_flags = TH_RST; 993 } else { 994 if (flags & TH_SYN) 995 seq++; 996 th->th_ack = htonl(seq); 997 th->th_flags = TH_RST | TH_ACK; 998 } 999 } else { 1000 /* 1001 * Keepalive - use caller provided sequence numbers 1002 */ 1003 th->th_seq = htonl(seq); 1004 th->th_ack = htonl(ack); 1005 th->th_flags = TH_ACK; 1006 } 1007 1008 switch (id->addr_type) { 1009 case 4: 1010 th->th_sum = in_cksum(m, len); 1011 1012 /* finish the ip header */ 1013 h->ip_v = 4; 1014 h->ip_hl = sizeof(*h) >> 2; 1015 h->ip_tos = IPTOS_LOWDELAY; 1016 h->ip_off = 0; 1017 /* ip_len must be in host format for ip_output */ 1018 h->ip_len = len; 1019 h->ip_ttl = V_ip_defttl; 1020 h->ip_sum = 0; 1021 break; 1022#ifdef INET6 1023 case 6: 1024 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6), 1025 sizeof(struct tcphdr)); 1026 1027 /* finish the ip6 header */ 1028 h6->ip6_vfc |= IPV6_VERSION; 1029 h6->ip6_hlim = IPV6_DEFHLIM; 1030 break; 1031#endif 1032 } 1033 1034 return (m); 1035} 1036 1037/* 1038 * This procedure is only used to handle keepalives. It is invoked 1039 * every dyn_keepalive_period 1040 */ 1041static void 1042ipfw_tick(void * vnetx) 1043{ 1044 struct mbuf *m0, *m, *mnext, **mtailp; 1045#ifdef INET6 1046 struct mbuf *m6, **m6_tailp; 1047#endif 1048 int i; 1049 ipfw_dyn_rule *q; 1050#ifdef VIMAGE 1051 struct vnet *vp = vnetx; 1052#endif 1053 1054 CURVNET_SET(vp); 1055 if (V_dyn_keepalive == 0 || V_ipfw_dyn_v == NULL || V_dyn_count == 0) 1056 goto done; 1057 1058 /* 1059 * We make a chain of packets to go out here -- not deferring 1060 * until after we drop the IPFW dynamic rule lock would result 1061 * in a lock order reversal with the normal packet input -> ipfw 1062 * call stack. 1063 */ 1064 m0 = NULL; 1065 mtailp = &m0; 1066#ifdef INET6 1067 m6 = NULL; 1068 m6_tailp = &m6; 1069#endif 1070 IPFW_DYN_LOCK(); 1071 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 1072 for (q = V_ipfw_dyn_v[i] ; q ; q = q->next ) { 1073 if (q->dyn_type == O_LIMIT_PARENT) 1074 continue; 1075 if (q->id.proto != IPPROTO_TCP) 1076 continue; 1077 if ( (q->state & BOTH_SYN) != BOTH_SYN) 1078 continue; 1079 if (TIME_LEQ(time_uptime + V_dyn_keepalive_interval, 1080 q->expire)) 1081 continue; /* too early */ 1082 if (TIME_LEQ(q->expire, time_uptime)) 1083 continue; /* too late, rule expired */ 1084 1085 m = (q->state & ACK_REV) ? NULL : 1086 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, 1087 q->ack_fwd, TH_SYN); 1088 mnext = (q->state & ACK_FWD) ? NULL : 1089 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, 1090 q->ack_rev, 0); 1091 1092 switch (q->id.addr_type) { 1093 case 4: 1094 if (m != NULL) { 1095 *mtailp = m; 1096 mtailp = &(*mtailp)->m_nextpkt; 1097 } 1098 if (mnext != NULL) { 1099 *mtailp = mnext; 1100 mtailp = &(*mtailp)->m_nextpkt; 1101 } 1102 break; 1103#ifdef INET6 1104 case 6: 1105 if (m != NULL) { 1106 *m6_tailp = m; 1107 m6_tailp = &(*m6_tailp)->m_nextpkt; 1108 } 1109 if (mnext != NULL) { 1110 *m6_tailp = mnext; 1111 m6_tailp = &(*m6_tailp)->m_nextpkt; 1112 } 1113 break; 1114#endif 1115 } 1116 } 1117 } 1118 IPFW_DYN_UNLOCK(); 1119 for (m = m0; m != NULL; m = mnext) { 1120 mnext = m->m_nextpkt; 1121 m->m_nextpkt = NULL; 1122 ip_output(m, NULL, NULL, 0, NULL, NULL); 1123 } 1124#ifdef INET6 1125 for (m = m6; m != NULL; m = mnext) { 1126 mnext = m->m_nextpkt; 1127 m->m_nextpkt = NULL; 1128 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL); 1129 } 1130#endif 1131done: 1132 callout_reset_on(&V_ipfw_timeout, V_dyn_keepalive_period * hz, 1133 ipfw_tick, vnetx, 0); 1134 CURVNET_RESTORE(); 1135} 1136 1137void 1138ipfw_dyn_attach(void) 1139{ 1140 ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule", 1141 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL, 1142 UMA_ALIGN_PTR, 0); 1143 1144 IPFW_DYN_LOCK_INIT(); 1145} 1146 1147void 1148ipfw_dyn_detach(void) 1149{ 1150 uma_zdestroy(ipfw_dyn_rule_zone); 1151 IPFW_DYN_LOCK_DESTROY(); 1152} 1153 1154void 1155ipfw_dyn_init(void) 1156{ 1157 V_ipfw_dyn_v = NULL; 1158 V_dyn_buckets = 256; /* must be power of 2 */ 1159 V_curr_dyn_buckets = 256; /* must be power of 2 */ 1160 1161 V_dyn_ack_lifetime = 300; 1162 V_dyn_syn_lifetime = 20; 1163 V_dyn_fin_lifetime = 1; 1164 V_dyn_rst_lifetime = 1; 1165 V_dyn_udp_lifetime = 10; 1166 V_dyn_short_lifetime = 5; 1167 1168 V_dyn_keepalive_interval = 20; 1169 V_dyn_keepalive_period = 5; 1170 V_dyn_keepalive = 1; /* do send keepalives */ 1171 1172 V_dyn_max = 4096; /* max # of dynamic rules */ 1173 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE); 1174 callout_reset_on(&V_ipfw_timeout, hz, ipfw_tick, curvnet, 0); 1175} 1176 1177void 1178ipfw_dyn_uninit(int pass) 1179{ 1180 if (pass == 0) 1181 callout_drain(&V_ipfw_timeout); 1182 else { 1183 if (V_ipfw_dyn_v != NULL) 1184 free(V_ipfw_dyn_v, M_IPFW); 1185 } 1186} 1187 1188int 1189ipfw_dyn_len(void) 1190{ 1191 return (V_ipfw_dyn_v == NULL) ? 0 : 1192 (V_dyn_count * sizeof(ipfw_dyn_rule)); 1193} 1194 1195void 1196ipfw_get_dynamic(char **pbp, const char *ep) 1197{ 1198 ipfw_dyn_rule *p, *last = NULL; 1199 char *bp; 1200 int i; 1201 1202 if (V_ipfw_dyn_v == NULL) 1203 return; 1204 bp = *pbp; 1205 1206 IPFW_DYN_LOCK(); 1207 for (i = 0 ; i < V_curr_dyn_buckets; i++) 1208 for (p = V_ipfw_dyn_v[i] ; p != NULL; p = p->next) { 1209 if (bp + sizeof *p <= ep) { 1210 ipfw_dyn_rule *dst = 1211 (ipfw_dyn_rule *)bp; 1212 bcopy(p, dst, sizeof *p); 1213 bcopy(&(p->rule->rulenum), &(dst->rule), 1214 sizeof(p->rule->rulenum)); 1215 /* 1216 * store set number into high word of 1217 * dst->rule pointer. 1218 */ 1219 bcopy(&(p->rule->set), 1220 (char *)&dst->rule + 1221 sizeof(p->rule->rulenum), 1222 sizeof(p->rule->set)); 1223 /* 1224 * store a non-null value in "next". 1225 * The userland code will interpret a 1226 * NULL here as a marker 1227 * for the last dynamic rule. 1228 */ 1229 bcopy(&dst, &dst->next, sizeof(dst)); 1230 last = dst; 1231 dst->expire = 1232 TIME_LEQ(dst->expire, time_uptime) ? 1233 0 : dst->expire - time_uptime ; 1234 bp += sizeof(ipfw_dyn_rule); 1235 } 1236 } 1237 IPFW_DYN_UNLOCK(); 1238 if (last != NULL) /* mark last dynamic rule */ 1239 bzero(&last->next, sizeof(last)); 1240 *pbp = bp; 1241} 1242/* end of file */ 1243