sys/netinet/ipfw/ip_fw_dynamic.c

   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/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  */
 116 static VNET_DEFINE(ipfw_dyn_rule **, ipfw_dyn_v);
 117 static VNET_DEFINE(u_int32_t, dyn_buckets);
 118 static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
 119 static 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
 125 static uma_zone_t ipfw_dyn_rule_zone;
 126 #ifndef __FreeBSD__
 127 DEFINE_SPINLOCK(ipfw_dyn_mtx);
 128 #else
 129 static 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
 139 void
 140 ipfw_dyn_unlock(void)
 141 {
 142         IPFW_DYN_UNLOCK();
 143 }
 144
 145 /*
 146  * Timeouts for various events in handing dynamic rules.
 147  */
 148 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
 149 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
 150 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
 151 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
 152 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
 153 static 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
 170 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
 171 static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
 172 static 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
 178 static VNET_DEFINE(u_int32_t, dyn_count);       /* # of dynamic rules */
 179 static 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
 186 SYSBEGIN(f2)
 187
 188 SYSCTL_DECL(_net_inet_ip_fw);
 189 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
 190     CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0,
 191     "Number of dyn. buckets");
 192 SYSCTL_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");
 195 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_count,
 196     CTLFLAG_RD, &VNET_NAME(dyn_count), 0,
 197     "Number of dyn. rules");
 198 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_max,
 199     CTLFLAG_RW, &VNET_NAME(dyn_max), 0,
 200     "Max number of dyn. rules");
 201 SYSCTL_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");
 204 SYSCTL_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");
 207 SYSCTL_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");
 210 SYSCTL_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");
 213 SYSCTL_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");
 216 SYSCTL_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");
 219 SYSCTL_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
 223 SYSEND
 224
 225 #endif /* SYSCTL_NODE */
 226
 227
 228 static __inline int
 229 hash_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  */
 245 static __inline int
 246 hash_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
 260 static __inline void
 261 unlink_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  */
 320 static void
 321 remove_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          */
 344 next_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              }
 376 next:
 377                         prev=q;
 378                         q=q->next;
 379                 }
 380         }
 381         if (pass++ < max_pass)
 382                 goto next_pass;
 383 }
 384
 385 void
 386 ipfw_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  */
 396 static ipfw_dyn_rule *
 397 lookup_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                 }
 457 next:
 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         }
 539 done:
 540         if (match_direction != NULL)
 541                 *match_direction = dir;
 542         return (q);
 543 }
 544
 545 ipfw_dyn_rule *
 546 ipfw_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
 559 static void
 560 realloc_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  */
 598 static ipfw_dyn_rule *
 599 add_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  */
 674 static ipfw_dyn_rule *
 675 lookup_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  */
 716 int
 717 ipfw_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  */
 895 struct mbuf *
 896 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
 897     u_int32_t ack, int flags)
 898 {
 899 #ifndef __FreeBSD__
 900         return NULL;
 901 #else
 902         struct mbuf *m;
 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 #endif /* __FreeBSD__ */
1039 }
1040
1041 /*
1042  * This procedure is only used to handle keepalives. It is invoked
1043  * every dyn_keepalive_period
1044  */
1045 static void
1046 ipfw_tick(void * vnetx)
1047 {
1048         struct mbuf *m0, *m, *mnext, **mtailp;
1049 #ifdef INET6
1050         struct mbuf *m6, **m6_tailp;
1051 #endif
1052         int i;
1053         ipfw_dyn_rule *q;
1054 #ifdef VIMAGE
1055         struct vnet *vp = vnetx;
1056 #endif
1057
1058         CURVNET_SET(vp);
1059         if (V_dyn_keepalive == 0 || V_ipfw_dyn_v == NULL || V_dyn_count == 0)
1060                 goto done;
1061
1062         /*
1063          * We make a chain of packets to go out here -- not deferring
1064          * until after we drop the IPFW dynamic rule lock would result
1065          * in a lock order reversal with the normal packet input -> ipfw
1066          * call stack.
1067          */
1068         m0 = NULL;
1069         mtailp = &m0;
1070 #ifdef INET6
1071         m6 = NULL;
1072         m6_tailp = &m6;
1073 #endif
1074         IPFW_DYN_LOCK();
1075         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1076                 for (q = V_ipfw_dyn_v[i] ; q ; q = q->next ) {
1077                         if (q->dyn_type == O_LIMIT_PARENT)
1078                                 continue;
1079                         if (q->id.proto != IPPROTO_TCP)
1080                                 continue;
1081                         if ( (q->state & BOTH_SYN) != BOTH_SYN)
1082                                 continue;
1083                         if (TIME_LEQ(time_uptime + V_dyn_keepalive_interval,
1084                             q->expire))
1085                                 continue;       /* too early */
1086                         if (TIME_LEQ(q->expire, time_uptime))
1087                                 continue;       /* too late, rule expired */
1088
1089                         m = (q->state & ACK_REV) ? NULL :
1090                             ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1,
1091                             q->ack_fwd, TH_SYN);
1092                         mnext = (q->state & ACK_FWD) ? NULL :
1093                             ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1,
1094                             q->ack_rev, 0);
1095
1096                         switch (q->id.addr_type) {
1097                         case 4:
1098                                 if (m != NULL) {
1099                                         *mtailp = m;
1100                                         mtailp = &(*mtailp)->m_nextpkt;
1101                                 }
1102                                 if (mnext != NULL) {
1103                                         *mtailp = mnext;
1104                                         mtailp = &(*mtailp)->m_nextpkt;
1105                                 }
1106                                 break;
1107 #ifdef INET6
1108                         case 6:
1109                                 if (m != NULL) {
1110                                         *m6_tailp = m;
1111                                         m6_tailp = &(*m6_tailp)->m_nextpkt;
1112                                 }
1113                                 if (mnext != NULL) {
1114                                         *m6_tailp = mnext;
1115                                         m6_tailp = &(*m6_tailp)->m_nextpkt;
1116                                 }
1117                                 break;
1118 #endif
1119                         }
1120                 }
1121         }
1122         IPFW_DYN_UNLOCK();
1123         for (m = m0; m != NULL; m = mnext) {
1124                 mnext = m->m_nextpkt;
1125                 m->m_nextpkt = NULL;
1126                 ip_output(m, NULL, NULL, 0, NULL, NULL);
1127         }
1128 #ifdef INET6
1129         for (m = m6; m != NULL; m = mnext) {
1130                 mnext = m->m_nextpkt;
1131                 m->m_nextpkt = NULL;
1132                 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1133         }
1134 #endif
1135 done:
1136         callout_reset(&V_ipfw_timeout, V_dyn_keepalive_period * hz,
1137                       ipfw_tick, vnetx);
1138         CURVNET_RESTORE();
1139 }
1140
1141 void
1142 ipfw_dyn_attach(void)
1143 {
1144         ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1145             sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1146             UMA_ALIGN_PTR, 0);
1147
1148         IPFW_DYN_LOCK_INIT();
1149 }
1150
1151 void
1152 ipfw_dyn_detach(void)
1153 {
1154         uma_zdestroy(ipfw_dyn_rule_zone);
1155         IPFW_DYN_LOCK_DESTROY();
1156 }
1157
1158 void
1159 ipfw_dyn_init(void)
1160 {
1161         V_ipfw_dyn_v = NULL;
1162         V_dyn_buckets = 256;    /* must be power of 2 */
1163         V_curr_dyn_buckets = 256; /* must be power of 2 */
1164
1165         V_dyn_ack_lifetime = 300;
1166         V_dyn_syn_lifetime = 20;
1167         V_dyn_fin_lifetime = 1;
1168         V_dyn_rst_lifetime = 1;
1169         V_dyn_udp_lifetime = 10;
1170         V_dyn_short_lifetime = 5;
1171
1172         V_dyn_keepalive_interval = 20;
1173         V_dyn_keepalive_period = 5;
1174         V_dyn_keepalive = 1;    /* do send keepalives */
1175
1176         V_dyn_max = 4096;       /* max # of dynamic rules */
1177         callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1178         callout_reset(&V_ipfw_timeout, hz, ipfw_tick, curvnet);
1179 }
1180
1181 void
1182 ipfw_dyn_uninit(int pass)
1183 {
1184         if (pass == 0)
1185                 callout_drain(&V_ipfw_timeout);
1186         else {
1187                 if (V_ipfw_dyn_v != NULL)
1188                         free(V_ipfw_dyn_v, M_IPFW);
1189         }
1190 }
1191
1192 int
1193 ipfw_dyn_len(void)
1194 {
1195         return (V_ipfw_dyn_v == NULL) ? 0 :
1196                 (V_dyn_count * sizeof(ipfw_dyn_rule));
1197 }
1198
1199 void
1200 ipfw_get_dynamic(char **pbp, const char *ep)
1201 {
1202         ipfw_dyn_rule *p, *last = NULL;
1203         char *bp;
1204         int i;
1205
1206         if (V_ipfw_dyn_v == NULL)
1207                 return;
1208         bp = *pbp;
1209
1210         IPFW_DYN_LOCK();
1211         for (i = 0 ; i < V_curr_dyn_buckets; i++)
1212                 for (p = V_ipfw_dyn_v[i] ; p != NULL; p = p->next) {
1213                         if (bp + sizeof *p <= ep) {
1214                                 ipfw_dyn_rule *dst =
1215                                         (ipfw_dyn_rule *)bp;
1216                                 bcopy(p, dst, sizeof *p);
1217                                 bcopy(&(p->rule->rulenum), &(dst->rule),
1218                                     sizeof(p->rule->rulenum));
1219                                 /*
1220                                  * store set number into high word of
1221                                  * dst->rule pointer.
1222                                  */
1223                                 bcopy(&(p->rule->set),
1224                                     (char *)&dst->rule +
1225                                     sizeof(p->rule->rulenum),
1226                                     sizeof(p->rule->set));
1227                                 /*
1228                                  * store a non-null value in "next".
1229                                  * The userland code will interpret a
1230                                  * NULL here as a marker
1231                                  * for the last dynamic rule.
1232                                  */
1233                                 bcopy(&dst, &dst->next, sizeof(dst));
1234                                 last = dst;
1235                                 dst->expire =
1236                                     TIME_LEQ(dst->expire, time_uptime) ?
1237                                         0 : dst->expire - time_uptime ;
1238                                 bp += sizeof(ipfw_dyn_rule);
1239                         }
1240                 }
1241         IPFW_DYN_UNLOCK();
1242         if (last != NULL) /* mark last dynamic rule */
1243                 bzero(&last->next, sizeof(last));
1244         *pbp = bp;
1245 }
1246 /* end of file */