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/ktr.h> 49 #include <sys/lock.h> 50 #include <sys/rmlock.h> 51 #include <sys/socket.h> 52 #include <sys/sysctl.h> 53 #include <sys/syslog.h> 54 #include <net/ethernet.h> /* for ETHERTYPE_IP */ 55 #include <net/if.h> 56 #include <net/if_var.h> 57 #include <net/pfil.h> 58 #include <net/vnet.h> 59 60 #include <netinet/in.h> 61 #include <netinet/ip.h> 62 #include <netinet/ip_var.h> /* ip_defttl */ 63 #include <netinet/ip_fw.h> 64 #include <netinet/tcp_var.h> 65 #include <netinet/udp.h> 66 67 #include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */ 68 #ifdef INET6 69 #include <netinet6/in6_var.h> 70 #include <netinet6/ip6_var.h> 71 #endif 72 73 #include <netpfil/ipfw/ip_fw_private.h> 74 75 #include <machine/in_cksum.h> /* XXX for in_cksum */ 76 77 #ifdef MAC 78 #include <security/mac/mac_framework.h> 79 #endif 80 81 /* 82 * Description of dynamic rules. 83 * 84 * Dynamic rules are stored in lists accessed through a hash table 85 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can 86 * be modified through the sysctl variable dyn_buckets which is 87 * updated when the table becomes empty. 88 * 89 * XXX currently there is only one list, ipfw_dyn. 90 * 91 * When a packet is received, its address fields are first masked 92 * with the mask defined for the rule, then hashed, then matched 93 * against the entries in the corresponding list. 94 * Dynamic rules can be used for different purposes: 95 * + stateful rules; 96 * + enforcing limits on the number of sessions; 97 * + in-kernel NAT (not implemented yet) 98 * 99 * The lifetime of dynamic rules is regulated by dyn_*_lifetime, 100 * measured in seconds and depending on the flags. 101 * 102 * The total number of dynamic rules is equal to UMA zone items count. 103 * The max number of dynamic rules is dyn_max. When we reach 104 * the maximum number of rules we do not create anymore. This is 105 * done to avoid consuming too much memory, but also too much 106 * time when searching on each packet (ideally, we should try instead 107 * to put a limit on the length of the list on each bucket...). 108 * 109 * Each dynamic rule holds a pointer to the parent ipfw rule so 110 * we know what action to perform. Dynamic rules are removed when 111 * the parent rule is deleted. This can be changed by dyn_keep_states 112 * sysctl. 113 * 114 * There are some limitations with dynamic rules -- we do not 115 * obey the 'randomized match', and we do not do multiple 116 * passes through the firewall. XXX check the latter!!! 117 */ 118 119 struct ipfw_dyn_bucket { 120 struct mtx mtx; /* Bucket protecting lock */ 121 ipfw_dyn_rule *head; /* Pointer to first rule */ 122 }; 123 124 /* 125 * Static variables followed by global ones 126 */ 127 static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v); 128 static VNET_DEFINE(u_int32_t, dyn_buckets_max); 129 static VNET_DEFINE(u_int32_t, curr_dyn_buckets); 130 static VNET_DEFINE(struct callout, ipfw_timeout); 131 #define V_ipfw_dyn_v VNET(ipfw_dyn_v) 132 #define V_dyn_buckets_max VNET(dyn_buckets_max) 133 #define V_curr_dyn_buckets VNET(curr_dyn_buckets) 134 #define V_ipfw_timeout VNET(ipfw_timeout) 135 136 static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone); 137 #define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone) 138 139 #define IPFW_BUCK_LOCK_INIT(b) \ 140 mtx_init(&(b)->mtx, "IPFW dynamic bucket", NULL, MTX_DEF) 141 #define IPFW_BUCK_LOCK_DESTROY(b) \ 142 mtx_destroy(&(b)->mtx) 143 #define IPFW_BUCK_LOCK(i) mtx_lock(&V_ipfw_dyn_v[(i)].mtx) 144 #define IPFW_BUCK_UNLOCK(i) mtx_unlock(&V_ipfw_dyn_v[(i)].mtx) 145 #define IPFW_BUCK_ASSERT(i) mtx_assert(&V_ipfw_dyn_v[(i)].mtx, MA_OWNED) 146 147 148 static VNET_DEFINE(int, dyn_keep_states); 149 #define V_dyn_keep_states VNET(dyn_keep_states) 150 151 /* 152 * Timeouts for various events in handing dynamic rules. 153 */ 154 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime); 155 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime); 156 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime); 157 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime); 158 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime); 159 static VNET_DEFINE(u_int32_t, dyn_short_lifetime); 160 161 #define V_dyn_ack_lifetime VNET(dyn_ack_lifetime) 162 #define V_dyn_syn_lifetime VNET(dyn_syn_lifetime) 163 #define V_dyn_fin_lifetime VNET(dyn_fin_lifetime) 164 #define V_dyn_rst_lifetime VNET(dyn_rst_lifetime) 165 #define V_dyn_udp_lifetime VNET(dyn_udp_lifetime) 166 #define V_dyn_short_lifetime VNET(dyn_short_lifetime) 167 168 /* 169 * Keepalives are sent if dyn_keepalive is set. They are sent every 170 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval 171 * seconds of lifetime of a rule. 172 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower 173 * than dyn_keepalive_period. 174 */ 175 176 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval); 177 static VNET_DEFINE(u_int32_t, dyn_keepalive_period); 178 static VNET_DEFINE(u_int32_t, dyn_keepalive); 179 static VNET_DEFINE(time_t, dyn_keepalive_last); 180 181 #define V_dyn_keepalive_interval VNET(dyn_keepalive_interval) 182 #define V_dyn_keepalive_period VNET(dyn_keepalive_period) 183 #define V_dyn_keepalive VNET(dyn_keepalive) 184 #define V_dyn_keepalive_last VNET(dyn_keepalive_last) 185 186 static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */ 187 188 #define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone) 189 #define V_dyn_max VNET(dyn_max) 190 191 /* for userspace, we emulate the uma_zone_counter with ipfw_dyn_count */ 192 static int ipfw_dyn_count; /* number of objects */ 193 194 #ifdef USERSPACE /* emulation of UMA object counters for userspace */ 195 #define uma_zone_get_cur(x) ipfw_dyn_count 196 #endif /* USERSPACE */ 197 198 static int last_log; /* Log ratelimiting */ 199 200 static void ipfw_dyn_tick(void *vnetx); 201 static void check_dyn_rules(struct ip_fw_chain *, ipfw_range_tlv *, int, int); 202 #ifdef SYSCTL_NODE 203 204 static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS); 205 static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS); 206 207 SYSBEGIN(f2) 208 209 SYSCTL_DECL(_net_inet_ip_fw); 210 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, 211 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_buckets_max), 0, 212 "Max number of dyn. buckets"); 213 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, 214 CTLFLAG_VNET | CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0, 215 "Current Number of dyn. buckets"); 216 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, dyn_count, 217 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RD, 0, 0, sysctl_ipfw_dyn_count, "IU", 218 "Number of dyn. rules"); 219 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, dyn_max, 220 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, 0, 0, sysctl_ipfw_dyn_max, "IU", 221 "Max number of dyn. rules"); 222 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, 223 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0, 224 "Lifetime of dyn. rules for acks"); 225 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, 226 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0, 227 "Lifetime of dyn. rules for syn"); 228 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, 229 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0, 230 "Lifetime of dyn. rules for fin"); 231 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, 232 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0, 233 "Lifetime of dyn. rules for rst"); 234 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, 235 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0, 236 "Lifetime of dyn. rules for UDP"); 237 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, 238 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0, 239 "Lifetime of dyn. rules for other situations"); 240 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, 241 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0, 242 "Enable keepalives for dyn. rules"); 243 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keep_states, 244 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_keep_states), 0, 245 "Do not flush dynamic states on rule deletion"); 246 247 SYSEND 248 249 #endif /* SYSCTL_NODE */ 250 251 252 #ifdef INET6 253 static __inline int 254 hash_packet6(struct ipfw_flow_id *id) 255 { 256 u_int32_t i; 257 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^ 258 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^ 259 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^ 260 (id->src_ip6.__u6_addr.__u6_addr32[3]); 261 return ntohl(i); 262 } 263 #endif 264 265 /* 266 * IMPORTANT: the hash function for dynamic rules must be commutative 267 * in source and destination (ip,port), because rules are bidirectional 268 * and we want to find both in the same bucket. 269 */ 270 static __inline int 271 hash_packet(struct ipfw_flow_id *id, int buckets) 272 { 273 u_int32_t i; 274 275 #ifdef INET6 276 if (IS_IP6_FLOW_ID(id)) 277 i = hash_packet6(id); 278 else 279 #endif /* INET6 */ 280 i = (id->dst_ip) ^ (id->src_ip); 281 i ^= (id->dst_port) ^ (id->src_port); 282 return (i & (buckets - 1)); 283 } 284 285 #if 0 286 #define DYN_DEBUG(fmt, ...) do { \ 287 printf("%s: " fmt "\n", __func__, __VA_ARGS__); \ 288 } while (0) 289 #else 290 #define DYN_DEBUG(fmt, ...) 291 #endif 292 293 static char *default_state_name = "default"; 294 struct dyn_state_obj { 295 struct named_object no; 296 char name[64]; 297 }; 298 299 #define DYN_STATE_OBJ(ch, cmd) \ 300 ((struct dyn_state_obj *)SRV_OBJECT(ch, (cmd)->arg1)) 301 /* 302 * Classifier callback. 303 * Return 0 if opcode contains object that should be referenced 304 * or rewritten. 305 */ 306 static int 307 dyn_classify(ipfw_insn *cmd, uint16_t *puidx, uint8_t *ptype) 308 { 309 310 DYN_DEBUG("opcode %d, arg1 %d", cmd->opcode, cmd->arg1); 311 /* Don't rewrite "check-state any" */ 312 if (cmd->arg1 == 0 && 313 cmd->opcode == O_CHECK_STATE) 314 return (1); 315 316 *puidx = cmd->arg1; 317 *ptype = 0; 318 return (0); 319 } 320 321 static void 322 dyn_update(ipfw_insn *cmd, uint16_t idx) 323 { 324 325 cmd->arg1 = idx; 326 DYN_DEBUG("opcode %d, arg1 %d", cmd->opcode, cmd->arg1); 327 } 328 329 static int 330 dyn_findbyname(struct ip_fw_chain *ch, struct tid_info *ti, 331 struct named_object **pno) 332 { 333 ipfw_obj_ntlv *ntlv; 334 const char *name; 335 336 DYN_DEBUG("uidx %d", ti->uidx); 337 if (ti->uidx != 0) { 338 if (ti->tlvs == NULL) 339 return (EINVAL); 340 /* Search ntlv in the buffer provided by user */ 341 ntlv = ipfw_find_name_tlv_type(ti->tlvs, ti->tlen, ti->uidx, 342 IPFW_TLV_STATE_NAME); 343 if (ntlv == NULL) 344 return (EINVAL); 345 name = ntlv->name; 346 } else 347 name = default_state_name; 348 /* 349 * Search named object with corresponding name. 350 * Since states objects are global - ignore the set value 351 * and use zero instead. 352 */ 353 *pno = ipfw_objhash_lookup_name_type(CHAIN_TO_SRV(ch), 0, 354 IPFW_TLV_STATE_NAME, name); 355 /* 356 * We always return success here. 357 * The caller will check *pno and mark object as unresolved, 358 * then it will automatically create "default" object. 359 */ 360 return (0); 361 } 362 363 static struct named_object * 364 dyn_findbykidx(struct ip_fw_chain *ch, uint16_t idx) 365 { 366 367 DYN_DEBUG("kidx %d", idx); 368 return (ipfw_objhash_lookup_kidx(CHAIN_TO_SRV(ch), idx)); 369 } 370 371 static int 372 dyn_create(struct ip_fw_chain *ch, struct tid_info *ti, 373 uint16_t *pkidx) 374 { 375 struct namedobj_instance *ni; 376 struct dyn_state_obj *obj; 377 struct named_object *no; 378 ipfw_obj_ntlv *ntlv; 379 char *name; 380 381 DYN_DEBUG("uidx %d", ti->uidx); 382 if (ti->uidx != 0) { 383 if (ti->tlvs == NULL) 384 return (EINVAL); 385 ntlv = ipfw_find_name_tlv_type(ti->tlvs, ti->tlen, ti->uidx, 386 IPFW_TLV_STATE_NAME); 387 if (ntlv == NULL) 388 return (EINVAL); 389 name = ntlv->name; 390 } else 391 name = default_state_name; 392 393 ni = CHAIN_TO_SRV(ch); 394 obj = malloc(sizeof(*obj), M_IPFW, M_WAITOK | M_ZERO); 395 obj->no.name = obj->name; 396 obj->no.etlv = IPFW_TLV_STATE_NAME; 397 strlcpy(obj->name, name, sizeof(obj->name)); 398 399 IPFW_UH_WLOCK(ch); 400 no = ipfw_objhash_lookup_name_type(ni, 0, 401 IPFW_TLV_STATE_NAME, name); 402 if (no != NULL) { 403 /* 404 * Object is already created. 405 * Just return its kidx and bump refcount. 406 */ 407 *pkidx = no->kidx; 408 no->refcnt++; 409 IPFW_UH_WUNLOCK(ch); 410 free(obj, M_IPFW); 411 DYN_DEBUG("\tfound kidx %d", *pkidx); 412 return (0); 413 } 414 if (ipfw_objhash_alloc_idx(ni, &obj->no.kidx) != 0) { 415 DYN_DEBUG("\talloc_idx failed for %s", name); 416 IPFW_UH_WUNLOCK(ch); 417 free(obj, M_IPFW); 418 return (ENOSPC); 419 } 420 ipfw_objhash_add(ni, &obj->no); 421 SRV_OBJECT(ch, obj->no.kidx) = obj; 422 obj->no.refcnt++; 423 *pkidx = obj->no.kidx; 424 IPFW_UH_WUNLOCK(ch); 425 DYN_DEBUG("\tcreated kidx %d", *pkidx); 426 return (0); 427 } 428 429 static void 430 dyn_destroy(struct ip_fw_chain *ch, struct named_object *no) 431 { 432 struct dyn_state_obj *obj; 433 434 IPFW_UH_WLOCK_ASSERT(ch); 435 436 KASSERT(no->refcnt == 1, 437 ("Destroying object '%s' (type %u, idx %u) with refcnt %u", 438 no->name, no->etlv, no->kidx, no->refcnt)); 439 440 DYN_DEBUG("kidx %d", no->kidx); 441 obj = SRV_OBJECT(ch, no->kidx); 442 SRV_OBJECT(ch, no->kidx) = NULL; 443 ipfw_objhash_del(CHAIN_TO_SRV(ch), no); 444 ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), no->kidx); 445 446 free(obj, M_IPFW); 447 } 448 449 static struct opcode_obj_rewrite dyn_opcodes[] = { 450 { 451 O_KEEP_STATE, IPFW_TLV_STATE_NAME, 452 dyn_classify, dyn_update, 453 dyn_findbyname, dyn_findbykidx, 454 dyn_create, dyn_destroy 455 }, 456 { 457 O_CHECK_STATE, IPFW_TLV_STATE_NAME, 458 dyn_classify, dyn_update, 459 dyn_findbyname, dyn_findbykidx, 460 dyn_create, dyn_destroy 461 }, 462 { 463 O_PROBE_STATE, IPFW_TLV_STATE_NAME, 464 dyn_classify, dyn_update, 465 dyn_findbyname, dyn_findbykidx, 466 dyn_create, dyn_destroy 467 }, 468 { 469 O_LIMIT, IPFW_TLV_STATE_NAME, 470 dyn_classify, dyn_update, 471 dyn_findbyname, dyn_findbykidx, 472 dyn_create, dyn_destroy 473 }, 474 }; 475 /** 476 * Print customizable flow id description via log(9) facility. 477 */ 478 static void 479 print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags, 480 char *prefix, char *postfix) 481 { 482 struct in_addr da; 483 #ifdef INET6 484 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN]; 485 #else 486 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN]; 487 #endif 488 489 #ifdef INET6 490 if (IS_IP6_FLOW_ID(id)) { 491 ip6_sprintf(src, &id->src_ip6); 492 ip6_sprintf(dst, &id->dst_ip6); 493 } else 494 #endif 495 { 496 da.s_addr = htonl(id->src_ip); 497 inet_ntop(AF_INET, &da, src, sizeof(src)); 498 da.s_addr = htonl(id->dst_ip); 499 inet_ntop(AF_INET, &da, dst, sizeof(dst)); 500 } 501 log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n", 502 prefix, dyn_type, src, id->src_port, dst, 503 id->dst_port, DYN_COUNT, postfix); 504 } 505 506 #define print_dyn_rule(id, dtype, prefix, postfix) \ 507 print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix) 508 509 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) 510 #define TIME_LE(a,b) ((int)((a)-(b)) < 0) 511 512 static void 513 dyn_update_proto_state(ipfw_dyn_rule *q, const struct ipfw_flow_id *id, 514 const struct tcphdr *tcp, int dir) 515 { 516 uint32_t ack; 517 u_char flags; 518 519 if (id->proto == IPPROTO_TCP) { 520 flags = id->_flags & (TH_FIN | TH_SYN | TH_RST); 521 #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) 522 #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) 523 #define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8)) 524 #define ACK_FWD 0x10000 /* fwd ack seen */ 525 #define ACK_REV 0x20000 /* rev ack seen */ 526 527 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8); 528 switch (q->state & TCP_FLAGS) { 529 case TH_SYN: /* opening */ 530 q->expire = time_uptime + V_dyn_syn_lifetime; 531 break; 532 533 case BOTH_SYN: /* move to established */ 534 case BOTH_SYN | TH_FIN: /* one side tries to close */ 535 case BOTH_SYN | (TH_FIN << 8): 536 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) 537 if (tcp == NULL) 538 break; 539 540 ack = ntohl(tcp->th_ack); 541 if (dir == MATCH_FORWARD) { 542 if (q->ack_fwd == 0 || 543 _SEQ_GE(ack, q->ack_fwd)) { 544 q->ack_fwd = ack; 545 q->state |= ACK_FWD; 546 } 547 } else { 548 if (q->ack_rev == 0 || 549 _SEQ_GE(ack, q->ack_rev)) { 550 q->ack_rev = ack; 551 q->state |= ACK_REV; 552 } 553 } 554 if ((q->state & (ACK_FWD | ACK_REV)) == 555 (ACK_FWD | ACK_REV)) { 556 q->expire = time_uptime + V_dyn_ack_lifetime; 557 q->state &= ~(ACK_FWD | ACK_REV); 558 } 559 break; 560 561 case BOTH_SYN | BOTH_FIN: /* both sides closed */ 562 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period) 563 V_dyn_fin_lifetime = 564 V_dyn_keepalive_period - 1; 565 q->expire = time_uptime + V_dyn_fin_lifetime; 566 break; 567 568 default: 569 #if 0 570 /* 571 * reset or some invalid combination, but can also 572 * occur if we use keep-state the wrong way. 573 */ 574 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) 575 printf("invalid state: 0x%x\n", q->state); 576 #endif 577 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period) 578 V_dyn_rst_lifetime = 579 V_dyn_keepalive_period - 1; 580 q->expire = time_uptime + V_dyn_rst_lifetime; 581 break; 582 } 583 } else if (id->proto == IPPROTO_UDP) { 584 q->expire = time_uptime + V_dyn_udp_lifetime; 585 } else { 586 /* other protocols */ 587 q->expire = time_uptime + V_dyn_short_lifetime; 588 } 589 } 590 591 /* 592 * Lookup a dynamic rule, locked version. 593 */ 594 static ipfw_dyn_rule * 595 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction, 596 struct tcphdr *tcp, uint16_t kidx) 597 { 598 /* 599 * Stateful ipfw extensions. 600 * Lookup into dynamic session queue. 601 */ 602 ipfw_dyn_rule *prev, *q = NULL; 603 int dir; 604 605 IPFW_BUCK_ASSERT(i); 606 607 dir = MATCH_NONE; 608 for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) { 609 if (q->dyn_type == O_LIMIT_PARENT) 610 continue; 611 612 if (pkt->proto != q->id.proto) 613 continue; 614 615 if (kidx != 0 && kidx != q->kidx) 616 continue; 617 618 if (IS_IP6_FLOW_ID(pkt)) { 619 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) && 620 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) && 621 pkt->src_port == q->id.src_port && 622 pkt->dst_port == q->id.dst_port) { 623 dir = MATCH_FORWARD; 624 break; 625 } 626 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) && 627 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) && 628 pkt->src_port == q->id.dst_port && 629 pkt->dst_port == q->id.src_port) { 630 dir = MATCH_REVERSE; 631 break; 632 } 633 } else { 634 if (pkt->src_ip == q->id.src_ip && 635 pkt->dst_ip == q->id.dst_ip && 636 pkt->src_port == q->id.src_port && 637 pkt->dst_port == q->id.dst_port) { 638 dir = MATCH_FORWARD; 639 break; 640 } 641 if (pkt->src_ip == q->id.dst_ip && 642 pkt->dst_ip == q->id.src_ip && 643 pkt->src_port == q->id.dst_port && 644 pkt->dst_port == q->id.src_port) { 645 dir = MATCH_REVERSE; 646 break; 647 } 648 } 649 } 650 if (q == NULL) 651 goto done; /* q = NULL, not found */ 652 653 if (prev != NULL) { /* found and not in front */ 654 prev->next = q->next; 655 q->next = V_ipfw_dyn_v[i].head; 656 V_ipfw_dyn_v[i].head = q; 657 } 658 659 /* update state according to flags */ 660 dyn_update_proto_state(q, pkt, tcp, dir); 661 done: 662 if (match_direction != NULL) 663 *match_direction = dir; 664 return (q); 665 } 666 667 ipfw_dyn_rule * 668 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, 669 struct tcphdr *tcp, uint16_t kidx) 670 { 671 ipfw_dyn_rule *q; 672 int i; 673 674 i = hash_packet(pkt, V_curr_dyn_buckets); 675 676 IPFW_BUCK_LOCK(i); 677 q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp, kidx); 678 if (q == NULL) 679 IPFW_BUCK_UNLOCK(i); 680 /* NB: return table locked when q is not NULL */ 681 return q; 682 } 683 684 /* 685 * Unlock bucket mtx 686 * @p - pointer to dynamic rule 687 */ 688 void 689 ipfw_dyn_unlock(ipfw_dyn_rule *q) 690 { 691 692 IPFW_BUCK_UNLOCK(q->bucket); 693 } 694 695 static int 696 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets) 697 { 698 int i, k, nbuckets_old; 699 ipfw_dyn_rule *q; 700 struct ipfw_dyn_bucket *dyn_v, *dyn_v_old; 701 702 /* Check if given number is power of 2 and less than 64k */ 703 if ((nbuckets > 65536) || (!powerof2(nbuckets))) 704 return 1; 705 706 CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__, 707 V_curr_dyn_buckets, nbuckets); 708 709 /* Allocate and initialize new hash */ 710 dyn_v = malloc(nbuckets * sizeof(*dyn_v), M_IPFW, 711 M_WAITOK | M_ZERO); 712 713 for (i = 0 ; i < nbuckets; i++) 714 IPFW_BUCK_LOCK_INIT(&dyn_v[i]); 715 716 /* 717 * Call upper half lock, as get_map() do to ease 718 * read-only access to dynamic rules hash from sysctl 719 */ 720 IPFW_UH_WLOCK(chain); 721 722 /* 723 * Acquire chain write lock to permit hash access 724 * for main traffic path without additional locks 725 */ 726 IPFW_WLOCK(chain); 727 728 /* Save old values */ 729 nbuckets_old = V_curr_dyn_buckets; 730 dyn_v_old = V_ipfw_dyn_v; 731 732 /* Skip relinking if array is not set up */ 733 if (V_ipfw_dyn_v == NULL) 734 V_curr_dyn_buckets = 0; 735 736 /* Re-link all dynamic states */ 737 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 738 while (V_ipfw_dyn_v[i].head != NULL) { 739 /* Remove from current chain */ 740 q = V_ipfw_dyn_v[i].head; 741 V_ipfw_dyn_v[i].head = q->next; 742 743 /* Get new hash value */ 744 k = hash_packet(&q->id, nbuckets); 745 q->bucket = k; 746 /* Add to the new head */ 747 q->next = dyn_v[k].head; 748 dyn_v[k].head = q; 749 } 750 } 751 752 /* Update current pointers/buckets values */ 753 V_curr_dyn_buckets = nbuckets; 754 V_ipfw_dyn_v = dyn_v; 755 756 IPFW_WUNLOCK(chain); 757 758 IPFW_UH_WUNLOCK(chain); 759 760 /* Start periodic callout on initial creation */ 761 if (dyn_v_old == NULL) { 762 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0); 763 return (0); 764 } 765 766 /* Destroy all mutexes */ 767 for (i = 0 ; i < nbuckets_old ; i++) 768 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]); 769 770 /* Free old hash */ 771 free(dyn_v_old, M_IPFW); 772 773 return 0; 774 } 775 776 /** 777 * Install state of type 'type' for a dynamic session. 778 * The hash table contains two type of rules: 779 * - regular rules (O_KEEP_STATE) 780 * - rules for sessions with limited number of sess per user 781 * (O_LIMIT). When they are created, the parent is 782 * increased by 1, and decreased on delete. In this case, 783 * the third parameter is the parent rule and not the chain. 784 * - "parent" rules for the above (O_LIMIT_PARENT). 785 */ 786 static ipfw_dyn_rule * 787 add_dyn_rule(struct ipfw_flow_id *id, int i, uint8_t dyn_type, 788 struct ip_fw *rule, uint16_t kidx) 789 { 790 ipfw_dyn_rule *r; 791 792 IPFW_BUCK_ASSERT(i); 793 794 r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO); 795 if (r == NULL) { 796 if (last_log != time_uptime) { 797 last_log = time_uptime; 798 log(LOG_DEBUG, 799 "ipfw: Cannot allocate dynamic state, " 800 "consider increasing net.inet.ip.fw.dyn_max\n"); 801 } 802 return NULL; 803 } 804 ipfw_dyn_count++; 805 806 /* 807 * refcount on parent is already incremented, so 808 * it is safe to use parent unlocked. 809 */ 810 if (dyn_type == O_LIMIT) { 811 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; 812 if ( parent->dyn_type != O_LIMIT_PARENT) 813 panic("invalid parent"); 814 r->parent = parent; 815 rule = parent->rule; 816 } 817 818 r->id = *id; 819 r->expire = time_uptime + V_dyn_syn_lifetime; 820 r->rule = rule; 821 r->dyn_type = dyn_type; 822 IPFW_ZERO_DYN_COUNTER(r); 823 r->count = 0; 824 r->kidx = kidx; 825 r->bucket = i; 826 r->next = V_ipfw_dyn_v[i].head; 827 V_ipfw_dyn_v[i].head = r; 828 DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");) 829 return r; 830 } 831 832 /** 833 * lookup dynamic parent rule using pkt and rule as search keys. 834 * If the lookup fails, then install one. 835 */ 836 static ipfw_dyn_rule * 837 lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule, 838 uint16_t kidx) 839 { 840 ipfw_dyn_rule *q; 841 int i, is_v6; 842 843 is_v6 = IS_IP6_FLOW_ID(pkt); 844 i = hash_packet( pkt, V_curr_dyn_buckets ); 845 *pindex = i; 846 IPFW_BUCK_LOCK(i); 847 for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next) 848 if (q->dyn_type == O_LIMIT_PARENT && 849 kidx == q->kidx && 850 rule == q->rule && 851 pkt->proto == q->id.proto && 852 pkt->src_port == q->id.src_port && 853 pkt->dst_port == q->id.dst_port && 854 ( 855 (is_v6 && 856 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6), 857 &(q->id.src_ip6)) && 858 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6), 859 &(q->id.dst_ip6))) || 860 (!is_v6 && 861 pkt->src_ip == q->id.src_ip && 862 pkt->dst_ip == q->id.dst_ip) 863 ) 864 ) { 865 q->expire = time_uptime + V_dyn_short_lifetime; 866 DEB(print_dyn_rule(pkt, q->dyn_type, 867 "lookup_dyn_parent found", "");) 868 return q; 869 } 870 871 /* Add virtual limiting rule */ 872 return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule, kidx); 873 } 874 875 /** 876 * Install dynamic state for rule type cmd->o.opcode 877 * 878 * Returns 1 (failure) if state is not installed because of errors or because 879 * session limitations are enforced. 880 */ 881 int 882 ipfw_install_state(struct ip_fw_chain *chain, struct ip_fw *rule, 883 ipfw_insn_limit *cmd, struct ip_fw_args *args, uint32_t tablearg) 884 { 885 ipfw_dyn_rule *q; 886 int i; 887 888 DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", 889 (cmd->o.arg1 == 0 ? "": DYN_STATE_OBJ(chain, &cmd->o)->name));) 890 891 i = hash_packet(&args->f_id, V_curr_dyn_buckets); 892 893 IPFW_BUCK_LOCK(i); 894 895 q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL, cmd->o.arg1); 896 if (q != NULL) { /* should never occur */ 897 DEB( 898 if (last_log != time_uptime) { 899 last_log = time_uptime; 900 printf("ipfw: %s: entry already present, done\n", 901 __func__); 902 }) 903 IPFW_BUCK_UNLOCK(i); 904 return (0); 905 } 906 907 /* 908 * State limiting is done via uma(9) zone limiting. 909 * Save pointer to newly-installed rule and reject 910 * packet if add_dyn_rule() returned NULL. 911 * Note q is currently set to NULL. 912 */ 913 914 switch (cmd->o.opcode) { 915 case O_KEEP_STATE: /* bidir rule */ 916 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule, 917 cmd->o.arg1); 918 break; 919 920 case O_LIMIT: { /* limit number of sessions */ 921 struct ipfw_flow_id id; 922 ipfw_dyn_rule *parent; 923 uint32_t conn_limit; 924 uint16_t limit_mask = cmd->limit_mask; 925 int pindex; 926 927 conn_limit = IP_FW_ARG_TABLEARG(chain, cmd->conn_limit, limit); 928 929 DEB( 930 if (cmd->conn_limit == IP_FW_TARG) 931 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u " 932 "(tablearg)\n", __func__, conn_limit); 933 else 934 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n", 935 __func__, conn_limit); 936 ) 937 938 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0; 939 id.proto = args->f_id.proto; 940 id.addr_type = args->f_id.addr_type; 941 id.fib = M_GETFIB(args->m); 942 943 if (IS_IP6_FLOW_ID (&(args->f_id))) { 944 bzero(&id.src_ip6, sizeof(id.src_ip6)); 945 bzero(&id.dst_ip6, sizeof(id.dst_ip6)); 946 947 if (limit_mask & DYN_SRC_ADDR) 948 id.src_ip6 = args->f_id.src_ip6; 949 if (limit_mask & DYN_DST_ADDR) 950 id.dst_ip6 = args->f_id.dst_ip6; 951 } else { 952 if (limit_mask & DYN_SRC_ADDR) 953 id.src_ip = args->f_id.src_ip; 954 if (limit_mask & DYN_DST_ADDR) 955 id.dst_ip = args->f_id.dst_ip; 956 } 957 if (limit_mask & DYN_SRC_PORT) 958 id.src_port = args->f_id.src_port; 959 if (limit_mask & DYN_DST_PORT) 960 id.dst_port = args->f_id.dst_port; 961 962 /* 963 * We have to release lock for previous bucket to 964 * avoid possible deadlock 965 */ 966 IPFW_BUCK_UNLOCK(i); 967 968 parent = lookup_dyn_parent(&id, &pindex, rule, cmd->o.arg1); 969 if (parent == NULL) { 970 printf("ipfw: %s: add parent failed\n", __func__); 971 IPFW_BUCK_UNLOCK(pindex); 972 return (1); 973 } 974 975 if (parent->count >= conn_limit) { 976 if (V_fw_verbose && last_log != time_uptime) { 977 char sbuf[24]; 978 last_log = time_uptime; 979 snprintf(sbuf, sizeof(sbuf), 980 "%d drop session", 981 parent->rule->rulenum); 982 print_dyn_rule_flags(&args->f_id, 983 cmd->o.opcode, 984 LOG_SECURITY | LOG_DEBUG, 985 sbuf, "too many entries"); 986 } 987 IPFW_BUCK_UNLOCK(pindex); 988 return (1); 989 } 990 /* Increment counter on parent */ 991 parent->count++; 992 IPFW_BUCK_UNLOCK(pindex); 993 994 IPFW_BUCK_LOCK(i); 995 q = add_dyn_rule(&args->f_id, i, O_LIMIT, 996 (struct ip_fw *)parent, cmd->o.arg1); 997 if (q == NULL) { 998 /* Decrement index and notify caller */ 999 IPFW_BUCK_UNLOCK(i); 1000 IPFW_BUCK_LOCK(pindex); 1001 parent->count--; 1002 IPFW_BUCK_UNLOCK(pindex); 1003 return (1); 1004 } 1005 break; 1006 } 1007 default: 1008 printf("ipfw: %s: unknown dynamic rule type %u\n", 1009 __func__, cmd->o.opcode); 1010 } 1011 1012 if (q == NULL) { 1013 IPFW_BUCK_UNLOCK(i); 1014 return (1); /* Notify caller about failure */ 1015 } 1016 1017 dyn_update_proto_state(q, &args->f_id, NULL, MATCH_FORWARD); 1018 IPFW_BUCK_UNLOCK(i); 1019 return (0); 1020 } 1021 1022 /* 1023 * Generate a TCP packet, containing either a RST or a keepalive. 1024 * When flags & TH_RST, we are sending a RST packet, because of a 1025 * "reset" action matched the packet. 1026 * Otherwise we are sending a keepalive, and flags & TH_ 1027 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required 1028 * so that MAC can label the reply appropriately. 1029 */ 1030 struct mbuf * 1031 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq, 1032 u_int32_t ack, int flags) 1033 { 1034 struct mbuf *m = NULL; /* stupid compiler */ 1035 int len, dir; 1036 struct ip *h = NULL; /* stupid compiler */ 1037 #ifdef INET6 1038 struct ip6_hdr *h6 = NULL; 1039 #endif 1040 struct tcphdr *th = NULL; 1041 1042 MGETHDR(m, M_NOWAIT, MT_DATA); 1043 if (m == NULL) 1044 return (NULL); 1045 1046 M_SETFIB(m, id->fib); 1047 #ifdef MAC 1048 if (replyto != NULL) 1049 mac_netinet_firewall_reply(replyto, m); 1050 else 1051 mac_netinet_firewall_send(m); 1052 #else 1053 (void)replyto; /* don't warn about unused arg */ 1054 #endif 1055 1056 switch (id->addr_type) { 1057 case 4: 1058 len = sizeof(struct ip) + sizeof(struct tcphdr); 1059 break; 1060 #ifdef INET6 1061 case 6: 1062 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1063 break; 1064 #endif 1065 default: 1066 /* XXX: log me?!? */ 1067 FREE_PKT(m); 1068 return (NULL); 1069 } 1070 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN); 1071 1072 m->m_data += max_linkhdr; 1073 m->m_flags |= M_SKIP_FIREWALL; 1074 m->m_pkthdr.len = m->m_len = len; 1075 m->m_pkthdr.rcvif = NULL; 1076 bzero(m->m_data, len); 1077 1078 switch (id->addr_type) { 1079 case 4: 1080 h = mtod(m, struct ip *); 1081 1082 /* prepare for checksum */ 1083 h->ip_p = IPPROTO_TCP; 1084 h->ip_len = htons(sizeof(struct tcphdr)); 1085 if (dir) { 1086 h->ip_src.s_addr = htonl(id->src_ip); 1087 h->ip_dst.s_addr = htonl(id->dst_ip); 1088 } else { 1089 h->ip_src.s_addr = htonl(id->dst_ip); 1090 h->ip_dst.s_addr = htonl(id->src_ip); 1091 } 1092 1093 th = (struct tcphdr *)(h + 1); 1094 break; 1095 #ifdef INET6 1096 case 6: 1097 h6 = mtod(m, struct ip6_hdr *); 1098 1099 /* prepare for checksum */ 1100 h6->ip6_nxt = IPPROTO_TCP; 1101 h6->ip6_plen = htons(sizeof(struct tcphdr)); 1102 if (dir) { 1103 h6->ip6_src = id->src_ip6; 1104 h6->ip6_dst = id->dst_ip6; 1105 } else { 1106 h6->ip6_src = id->dst_ip6; 1107 h6->ip6_dst = id->src_ip6; 1108 } 1109 1110 th = (struct tcphdr *)(h6 + 1); 1111 break; 1112 #endif 1113 } 1114 1115 if (dir) { 1116 th->th_sport = htons(id->src_port); 1117 th->th_dport = htons(id->dst_port); 1118 } else { 1119 th->th_sport = htons(id->dst_port); 1120 th->th_dport = htons(id->src_port); 1121 } 1122 th->th_off = sizeof(struct tcphdr) >> 2; 1123 1124 if (flags & TH_RST) { 1125 if (flags & TH_ACK) { 1126 th->th_seq = htonl(ack); 1127 th->th_flags = TH_RST; 1128 } else { 1129 if (flags & TH_SYN) 1130 seq++; 1131 th->th_ack = htonl(seq); 1132 th->th_flags = TH_RST | TH_ACK; 1133 } 1134 } else { 1135 /* 1136 * Keepalive - use caller provided sequence numbers 1137 */ 1138 th->th_seq = htonl(seq); 1139 th->th_ack = htonl(ack); 1140 th->th_flags = TH_ACK; 1141 } 1142 1143 switch (id->addr_type) { 1144 case 4: 1145 th->th_sum = in_cksum(m, len); 1146 1147 /* finish the ip header */ 1148 h->ip_v = 4; 1149 h->ip_hl = sizeof(*h) >> 2; 1150 h->ip_tos = IPTOS_LOWDELAY; 1151 h->ip_off = htons(0); 1152 h->ip_len = htons(len); 1153 h->ip_ttl = V_ip_defttl; 1154 h->ip_sum = 0; 1155 break; 1156 #ifdef INET6 1157 case 6: 1158 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6), 1159 sizeof(struct tcphdr)); 1160 1161 /* finish the ip6 header */ 1162 h6->ip6_vfc |= IPV6_VERSION; 1163 h6->ip6_hlim = IPV6_DEFHLIM; 1164 break; 1165 #endif 1166 } 1167 1168 return (m); 1169 } 1170 1171 /* 1172 * Queue keepalive packets for given dynamic rule 1173 */ 1174 static struct mbuf ** 1175 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q) 1176 { 1177 struct mbuf *m_rev, *m_fwd; 1178 1179 m_rev = (q->state & ACK_REV) ? NULL : 1180 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); 1181 m_fwd = (q->state & ACK_FWD) ? NULL : 1182 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0); 1183 1184 if (m_rev != NULL) { 1185 *mtailp = m_rev; 1186 mtailp = &(*mtailp)->m_nextpkt; 1187 } 1188 if (m_fwd != NULL) { 1189 *mtailp = m_fwd; 1190 mtailp = &(*mtailp)->m_nextpkt; 1191 } 1192 1193 return (mtailp); 1194 } 1195 1196 /* 1197 * This procedure is used to perform various maintenance 1198 * on dynamic hash list. Currently it is called every second. 1199 */ 1200 static void 1201 ipfw_dyn_tick(void * vnetx) 1202 { 1203 struct ip_fw_chain *chain; 1204 int check_ka = 0; 1205 #ifdef VIMAGE 1206 struct vnet *vp = vnetx; 1207 #endif 1208 1209 CURVNET_SET(vp); 1210 1211 chain = &V_layer3_chain; 1212 1213 /* Run keepalive checks every keepalive_period iff ka is enabled */ 1214 if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) && 1215 (V_dyn_keepalive != 0)) { 1216 V_dyn_keepalive_last = time_uptime; 1217 check_ka = 1; 1218 } 1219 1220 check_dyn_rules(chain, NULL, check_ka, 1); 1221 1222 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0); 1223 1224 CURVNET_RESTORE(); 1225 } 1226 1227 1228 /* 1229 * Walk through all dynamic states doing generic maintenance: 1230 * 1) free expired states 1231 * 2) free all states based on deleted rule / set 1232 * 3) send keepalives for states if needed 1233 * 1234 * @chain - pointer to current ipfw rules chain 1235 * @rule - delete all states originated by given rule if != NULL 1236 * @set - delete all states originated by any rule in set @set if != RESVD_SET 1237 * @check_ka - perform checking/sending keepalives 1238 * @timer - indicate call from timer routine. 1239 * 1240 * Timer routine must call this function unlocked to permit 1241 * sending keepalives/resizing table. 1242 * 1243 * Others has to call function with IPFW_UH_WLOCK held. 1244 * Additionally, function assume that dynamic rule/set is 1245 * ALREADY deleted so no new states can be generated by 1246 * 'deleted' rules. 1247 * 1248 * Write lock is needed to ensure that unused parent rules 1249 * are not freed by other instance (see stage 2, 3) 1250 */ 1251 static void 1252 check_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt, 1253 int check_ka, int timer) 1254 { 1255 struct mbuf *m0, *m, *mnext, **mtailp; 1256 struct ip *h; 1257 int i, dyn_count, new_buckets = 0, max_buckets; 1258 int expired = 0, expired_limits = 0, parents = 0, total = 0; 1259 ipfw_dyn_rule *q, *q_prev, *q_next; 1260 ipfw_dyn_rule *exp_head, **exptailp; 1261 ipfw_dyn_rule *exp_lhead, **expltailp; 1262 1263 KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated", 1264 __func__)); 1265 1266 /* Avoid possible LOR */ 1267 KASSERT(!check_ka || timer, ("%s: keepalive check with lock held", 1268 __func__)); 1269 1270 /* 1271 * Do not perform any checks if we currently have no dynamic states 1272 */ 1273 if (DYN_COUNT == 0) 1274 return; 1275 1276 /* Expired states */ 1277 exp_head = NULL; 1278 exptailp = &exp_head; 1279 1280 /* Expired limit states */ 1281 exp_lhead = NULL; 1282 expltailp = &exp_lhead; 1283 1284 /* 1285 * We make a chain of packets to go out here -- not deferring 1286 * until after we drop the IPFW dynamic rule lock would result 1287 * in a lock order reversal with the normal packet input -> ipfw 1288 * call stack. 1289 */ 1290 m0 = NULL; 1291 mtailp = &m0; 1292 1293 /* Protect from hash resizing */ 1294 if (timer != 0) 1295 IPFW_UH_WLOCK(chain); 1296 else 1297 IPFW_UH_WLOCK_ASSERT(chain); 1298 1299 #define NEXT_RULE() { q_prev = q; q = q->next ; continue; } 1300 1301 /* Stage 1: perform requested deletion */ 1302 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 1303 IPFW_BUCK_LOCK(i); 1304 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) { 1305 /* account every rule */ 1306 total++; 1307 1308 /* Skip parent rules at all */ 1309 if (q->dyn_type == O_LIMIT_PARENT) { 1310 parents++; 1311 NEXT_RULE(); 1312 } 1313 1314 /* 1315 * Remove rules which are: 1316 * 1) expired 1317 * 2) matches deletion range 1318 */ 1319 if ((TIME_LEQ(q->expire, time_uptime)) || 1320 (rt != NULL && ipfw_match_range(q->rule, rt))) { 1321 if (TIME_LE(time_uptime, q->expire) && 1322 q->dyn_type == O_KEEP_STATE && 1323 V_dyn_keep_states != 0) { 1324 /* 1325 * Do not delete state if 1326 * it is not expired and 1327 * dyn_keep_states is ON. 1328 * However we need to re-link it 1329 * to any other stable rule 1330 */ 1331 q->rule = chain->default_rule; 1332 NEXT_RULE(); 1333 } 1334 1335 /* Unlink q from current list */ 1336 q_next = q->next; 1337 if (q == V_ipfw_dyn_v[i].head) 1338 V_ipfw_dyn_v[i].head = q_next; 1339 else 1340 q_prev->next = q_next; 1341 1342 q->next = NULL; 1343 1344 /* queue q to expire list */ 1345 if (q->dyn_type != O_LIMIT) { 1346 *exptailp = q; 1347 exptailp = &(*exptailp)->next; 1348 DEB(print_dyn_rule(&q->id, q->dyn_type, 1349 "unlink entry", "left"); 1350 ) 1351 } else { 1352 /* Separate list for limit rules */ 1353 *expltailp = q; 1354 expltailp = &(*expltailp)->next; 1355 expired_limits++; 1356 DEB(print_dyn_rule(&q->id, q->dyn_type, 1357 "unlink limit entry", "left"); 1358 ) 1359 } 1360 1361 q = q_next; 1362 expired++; 1363 continue; 1364 } 1365 1366 /* 1367 * Check if we need to send keepalive: 1368 * we need to ensure if is time to do KA, 1369 * this is established TCP session, and 1370 * expire time is within keepalive interval 1371 */ 1372 if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) && 1373 ((q->state & BOTH_SYN) == BOTH_SYN) && 1374 (TIME_LEQ(q->expire, time_uptime + 1375 V_dyn_keepalive_interval))) 1376 mtailp = ipfw_dyn_send_ka(mtailp, q); 1377 1378 NEXT_RULE(); 1379 } 1380 IPFW_BUCK_UNLOCK(i); 1381 } 1382 1383 /* Stage 2: decrement counters from O_LIMIT parents */ 1384 if (expired_limits != 0) { 1385 /* 1386 * XXX: Note that deleting set with more than one 1387 * heavily-used LIMIT rules can result in overwhelming 1388 * locking due to lack of per-hash value sorting 1389 * 1390 * We should probably think about: 1391 * 1) pre-allocating hash of size, say, 1392 * MAX(16, V_curr_dyn_buckets / 1024) 1393 * 2) checking if expired_limits is large enough 1394 * 3) If yes, init hash (or its part), re-link 1395 * current list and start decrementing procedure in 1396 * each bucket separately 1397 */ 1398 1399 /* 1400 * Small optimization: do not unlock bucket until 1401 * we see the next item resides in different bucket 1402 */ 1403 if (exp_lhead != NULL) { 1404 i = exp_lhead->parent->bucket; 1405 IPFW_BUCK_LOCK(i); 1406 } 1407 for (q = exp_lhead; q != NULL; q = q->next) { 1408 if (i != q->parent->bucket) { 1409 IPFW_BUCK_UNLOCK(i); 1410 i = q->parent->bucket; 1411 IPFW_BUCK_LOCK(i); 1412 } 1413 1414 /* Decrease parent refcount */ 1415 q->parent->count--; 1416 } 1417 if (exp_lhead != NULL) 1418 IPFW_BUCK_UNLOCK(i); 1419 } 1420 1421 /* 1422 * We protectet ourselves from unused parent deletion 1423 * (from the timer function) by holding UH write lock. 1424 */ 1425 1426 /* Stage 3: remove unused parent rules */ 1427 if ((parents != 0) && (expired != 0)) { 1428 for (i = 0 ; i < V_curr_dyn_buckets ; i++) { 1429 IPFW_BUCK_LOCK(i); 1430 for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) { 1431 if (q->dyn_type != O_LIMIT_PARENT) 1432 NEXT_RULE(); 1433 1434 if (q->count != 0) 1435 NEXT_RULE(); 1436 1437 /* Parent rule without consumers */ 1438 1439 /* Unlink q from current list */ 1440 q_next = q->next; 1441 if (q == V_ipfw_dyn_v[i].head) 1442 V_ipfw_dyn_v[i].head = q_next; 1443 else 1444 q_prev->next = q_next; 1445 1446 q->next = NULL; 1447 1448 /* Add to expired list */ 1449 *exptailp = q; 1450 exptailp = &(*exptailp)->next; 1451 1452 DEB(print_dyn_rule(&q->id, q->dyn_type, 1453 "unlink parent entry", "left"); 1454 ) 1455 1456 expired++; 1457 1458 q = q_next; 1459 } 1460 IPFW_BUCK_UNLOCK(i); 1461 } 1462 } 1463 1464 #undef NEXT_RULE 1465 1466 if (timer != 0) { 1467 /* 1468 * Check if we need to resize hash: 1469 * if current number of states exceeds number of buckes in hash, 1470 * grow hash size to the minimum power of 2 which is bigger than 1471 * current states count. Limit hash size by 64k. 1472 */ 1473 max_buckets = (V_dyn_buckets_max > 65536) ? 1474 65536 : V_dyn_buckets_max; 1475 1476 dyn_count = DYN_COUNT; 1477 1478 if ((dyn_count > V_curr_dyn_buckets * 2) && 1479 (dyn_count < max_buckets)) { 1480 new_buckets = V_curr_dyn_buckets; 1481 while (new_buckets < dyn_count) { 1482 new_buckets *= 2; 1483 1484 if (new_buckets >= max_buckets) 1485 break; 1486 } 1487 } 1488 1489 IPFW_UH_WUNLOCK(chain); 1490 } 1491 1492 /* Finally delete old states ad limits if any */ 1493 for (q = exp_head; q != NULL; q = q_next) { 1494 q_next = q->next; 1495 uma_zfree(V_ipfw_dyn_rule_zone, q); 1496 ipfw_dyn_count--; 1497 } 1498 1499 for (q = exp_lhead; q != NULL; q = q_next) { 1500 q_next = q->next; 1501 uma_zfree(V_ipfw_dyn_rule_zone, q); 1502 ipfw_dyn_count--; 1503 } 1504 1505 /* 1506 * The rest code MUST be called from timer routine only 1507 * without holding any locks 1508 */ 1509 if (timer == 0) 1510 return; 1511 1512 /* Send keepalive packets if any */ 1513 for (m = m0; m != NULL; m = mnext) { 1514 mnext = m->m_nextpkt; 1515 m->m_nextpkt = NULL; 1516 h = mtod(m, struct ip *); 1517 if (h->ip_v == 4) 1518 ip_output(m, NULL, NULL, 0, NULL, NULL); 1519 #ifdef INET6 1520 else 1521 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL); 1522 #endif 1523 } 1524 1525 /* Run table resize without holding any locks */ 1526 if (new_buckets != 0) 1527 resize_dynamic_table(chain, new_buckets); 1528 } 1529 1530 /* 1531 * Deletes all dynamic rules originated by given rule or all rules in 1532 * given set. Specify RESVD_SET to indicate set should not be used. 1533 * @chain - pointer to current ipfw rules chain 1534 * @rr - delete all states originated by rules in matched range. 1535 * 1536 * Function has to be called with IPFW_UH_WLOCK held. 1537 * Additionally, function assume that dynamic rule/set is 1538 * ALREADY deleted so no new states can be generated by 1539 * 'deleted' rules. 1540 */ 1541 void 1542 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt) 1543 { 1544 1545 check_dyn_rules(chain, rt, 0, 0); 1546 } 1547 1548 /* 1549 * Check if rule contains at least one dynamic opcode. 1550 * 1551 * Returns 1 if such opcode is found, 0 otherwise. 1552 */ 1553 int 1554 ipfw_is_dyn_rule(struct ip_fw *rule) 1555 { 1556 int cmdlen, l; 1557 ipfw_insn *cmd; 1558 1559 l = rule->cmd_len; 1560 cmd = rule->cmd; 1561 cmdlen = 0; 1562 for ( ; l > 0 ; l -= cmdlen, cmd += cmdlen) { 1563 cmdlen = F_LEN(cmd); 1564 1565 switch (cmd->opcode) { 1566 case O_LIMIT: 1567 case O_KEEP_STATE: 1568 case O_PROBE_STATE: 1569 case O_CHECK_STATE: 1570 return (1); 1571 } 1572 } 1573 1574 return (0); 1575 } 1576 1577 void 1578 ipfw_dyn_init(struct ip_fw_chain *chain) 1579 { 1580 1581 V_ipfw_dyn_v = NULL; 1582 V_dyn_buckets_max = 256; /* must be power of 2 */ 1583 V_curr_dyn_buckets = 256; /* must be power of 2 */ 1584 1585 V_dyn_ack_lifetime = 300; 1586 V_dyn_syn_lifetime = 20; 1587 V_dyn_fin_lifetime = 1; 1588 V_dyn_rst_lifetime = 1; 1589 V_dyn_udp_lifetime = 10; 1590 V_dyn_short_lifetime = 5; 1591 1592 V_dyn_keepalive_interval = 20; 1593 V_dyn_keepalive_period = 5; 1594 V_dyn_keepalive = 1; /* do send keepalives */ 1595 V_dyn_keepalive_last = time_uptime; 1596 1597 V_dyn_max = 16384; /* max # of dynamic rules */ 1598 1599 V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule", 1600 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL, 1601 UMA_ALIGN_PTR, 0); 1602 1603 /* Enforce limit on dynamic rules */ 1604 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max); 1605 1606 callout_init(&V_ipfw_timeout, 1); 1607 1608 /* 1609 * This can potentially be done on first dynamic rule 1610 * being added to chain. 1611 */ 1612 resize_dynamic_table(chain, V_curr_dyn_buckets); 1613 IPFW_ADD_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes); 1614 } 1615 1616 void 1617 ipfw_dyn_uninit(int pass) 1618 { 1619 int i; 1620 1621 if (pass == 0) { 1622 callout_drain(&V_ipfw_timeout); 1623 return; 1624 } 1625 IPFW_DEL_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes); 1626 1627 if (V_ipfw_dyn_v != NULL) { 1628 /* 1629 * Skip deleting all dynamic states - 1630 * uma_zdestroy() does this more efficiently; 1631 */ 1632 1633 /* Destroy all mutexes */ 1634 for (i = 0 ; i < V_curr_dyn_buckets ; i++) 1635 IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]); 1636 free(V_ipfw_dyn_v, M_IPFW); 1637 V_ipfw_dyn_v = NULL; 1638 } 1639 1640 uma_zdestroy(V_ipfw_dyn_rule_zone); 1641 } 1642 1643 #ifdef SYSCTL_NODE 1644 /* 1645 * Get/set maximum number of dynamic states in given VNET instance. 1646 */ 1647 static int 1648 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS) 1649 { 1650 int error; 1651 unsigned int nstates; 1652 1653 nstates = V_dyn_max; 1654 1655 error = sysctl_handle_int(oidp, &nstates, 0, req); 1656 /* Read operation or some error */ 1657 if ((error != 0) || (req->newptr == NULL)) 1658 return (error); 1659 1660 V_dyn_max = nstates; 1661 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max); 1662 1663 return (0); 1664 } 1665 1666 /* 1667 * Get current number of dynamic states in given VNET instance. 1668 */ 1669 static int 1670 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS) 1671 { 1672 int error; 1673 unsigned int nstates; 1674 1675 nstates = DYN_COUNT; 1676 1677 error = sysctl_handle_int(oidp, &nstates, 0, req); 1678 1679 return (error); 1680 } 1681 #endif 1682 1683 /* 1684 * Returns size of dynamic states in legacy format 1685 */ 1686 int 1687 ipfw_dyn_len(void) 1688 { 1689 1690 return (V_ipfw_dyn_v == NULL) ? 0 : 1691 (DYN_COUNT * sizeof(ipfw_dyn_rule)); 1692 } 1693 1694 /* 1695 * Returns number of dynamic states. 1696 * Used by dump format v1 (current). 1697 */ 1698 int 1699 ipfw_dyn_get_count(void) 1700 { 1701 1702 return (V_ipfw_dyn_v == NULL) ? 0 : DYN_COUNT; 1703 } 1704 1705 static void 1706 export_dyn_rule(ipfw_dyn_rule *src, ipfw_dyn_rule *dst) 1707 { 1708 uint16_t rulenum; 1709 1710 rulenum = (uint16_t)src->rule->rulenum; 1711 memcpy(dst, src, sizeof(*src)); 1712 memcpy(&dst->rule, &rulenum, sizeof(rulenum)); 1713 /* 1714 * store set number into high word of 1715 * dst->rule pointer. 1716 */ 1717 memcpy((char *)&dst->rule + sizeof(rulenum), &src->rule->set, 1718 sizeof(src->rule->set)); 1719 /* 1720 * store a non-null value in "next". 1721 * The userland code will interpret a 1722 * NULL here as a marker 1723 * for the last dynamic rule. 1724 */ 1725 memcpy(&dst->next, &dst, sizeof(dst)); 1726 dst->expire = TIME_LEQ(dst->expire, time_uptime) ? 0: 1727 dst->expire - time_uptime; 1728 } 1729 1730 /* 1731 * Fills int buffer given by @sd with dynamic states. 1732 * Used by dump format v1 (current). 1733 * 1734 * Returns 0 on success. 1735 */ 1736 int 1737 ipfw_dump_states(struct ip_fw_chain *chain, struct sockopt_data *sd) 1738 { 1739 ipfw_dyn_rule *p; 1740 ipfw_obj_dyntlv *dst, *last; 1741 ipfw_obj_ctlv *ctlv; 1742 int i; 1743 size_t sz; 1744 1745 if (V_ipfw_dyn_v == NULL) 1746 return (0); 1747 1748 IPFW_UH_RLOCK_ASSERT(chain); 1749 1750 ctlv = (ipfw_obj_ctlv *)ipfw_get_sopt_space(sd, sizeof(*ctlv)); 1751 if (ctlv == NULL) 1752 return (ENOMEM); 1753 sz = sizeof(ipfw_obj_dyntlv); 1754 ctlv->head.type = IPFW_TLV_DYNSTATE_LIST; 1755 ctlv->objsize = sz; 1756 last = NULL; 1757 1758 for (i = 0 ; i < V_curr_dyn_buckets; i++) { 1759 IPFW_BUCK_LOCK(i); 1760 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) { 1761 dst = (ipfw_obj_dyntlv *)ipfw_get_sopt_space(sd, sz); 1762 if (dst == NULL) { 1763 IPFW_BUCK_UNLOCK(i); 1764 return (ENOMEM); 1765 } 1766 1767 export_dyn_rule(p, &dst->state); 1768 dst->head.length = sz; 1769 dst->head.type = IPFW_TLV_DYN_ENT; 1770 last = dst; 1771 } 1772 IPFW_BUCK_UNLOCK(i); 1773 } 1774 1775 if (last != NULL) /* mark last dynamic rule */ 1776 last->head.flags = IPFW_DF_LAST; 1777 1778 return (0); 1779 } 1780 1781 /* 1782 * Fill given buffer with dynamic states (legacy format). 1783 * IPFW_UH_RLOCK has to be held while calling. 1784 */ 1785 void 1786 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep) 1787 { 1788 ipfw_dyn_rule *p, *last = NULL; 1789 char *bp; 1790 int i; 1791 1792 if (V_ipfw_dyn_v == NULL) 1793 return; 1794 bp = *pbp; 1795 1796 IPFW_UH_RLOCK_ASSERT(chain); 1797 1798 for (i = 0 ; i < V_curr_dyn_buckets; i++) { 1799 IPFW_BUCK_LOCK(i); 1800 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) { 1801 if (bp + sizeof *p <= ep) { 1802 ipfw_dyn_rule *dst = 1803 (ipfw_dyn_rule *)bp; 1804 1805 export_dyn_rule(p, dst); 1806 last = dst; 1807 bp += sizeof(ipfw_dyn_rule); 1808 } 1809 } 1810 IPFW_BUCK_UNLOCK(i); 1811 } 1812 1813 if (last != NULL) /* mark last dynamic rule */ 1814 bzero(&last->next, sizeof(last)); 1815 *pbp = bp; 1816 } 1817 /* end of file */ 1818