sys/netpfil/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/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         IPFW_WLOCK(ch);
 422         SRV_OBJECT(ch, obj->no.kidx) = obj;
 423         IPFW_WUNLOCK(ch);
 424         obj->no.refcnt++;
 425         *pkidx = obj->no.kidx;
 426         IPFW_UH_WUNLOCK(ch);
 427         DYN_DEBUG("\tcreated kidx %d", *pkidx);
 428         return (0);
 429 }
 430
 431 static void
 432 dyn_destroy(struct ip_fw_chain *ch, struct named_object *no)
 433 {
 434         struct dyn_state_obj *obj;
 435
 436         IPFW_UH_WLOCK_ASSERT(ch);
 437
 438         KASSERT(no->refcnt == 1,
 439             ("Destroying object '%s' (type %u, idx %u) with refcnt %u",
 440             no->name, no->etlv, no->kidx, no->refcnt));
 441
 442         DYN_DEBUG("kidx %d", no->kidx);
 443         IPFW_WLOCK(ch);
 444         obj = SRV_OBJECT(ch, no->kidx);
 445         SRV_OBJECT(ch, no->kidx) = NULL;
 446         IPFW_WUNLOCK(ch);
 447         ipfw_objhash_del(CHAIN_TO_SRV(ch), no);
 448         ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), no->kidx);
 449
 450         free(obj, M_IPFW);
 451 }
 452
 453 static struct opcode_obj_rewrite dyn_opcodes[] = {
 454         {
 455                 O_KEEP_STATE, IPFW_TLV_STATE_NAME,
 456                 dyn_classify, dyn_update,
 457                 dyn_findbyname, dyn_findbykidx,
 458                 dyn_create, dyn_destroy
 459         },
 460         {
 461                 O_CHECK_STATE, IPFW_TLV_STATE_NAME,
 462                 dyn_classify, dyn_update,
 463                 dyn_findbyname, dyn_findbykidx,
 464                 dyn_create, dyn_destroy
 465         },
 466         {
 467                 O_PROBE_STATE, IPFW_TLV_STATE_NAME,
 468                 dyn_classify, dyn_update,
 469                 dyn_findbyname, dyn_findbykidx,
 470                 dyn_create, dyn_destroy
 471         },
 472         {
 473                 O_LIMIT, IPFW_TLV_STATE_NAME,
 474                 dyn_classify, dyn_update,
 475                 dyn_findbyname, dyn_findbykidx,
 476                 dyn_create, dyn_destroy
 477         },
 478 };
 479 /**
 480  * Print customizable flow id description via log(9) facility.
 481  */
 482 static void
 483 print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
 484     char *prefix, char *postfix)
 485 {
 486         struct in_addr da;
 487 #ifdef INET6
 488         char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
 489 #else
 490         char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
 491 #endif
 492
 493 #ifdef INET6
 494         if (IS_IP6_FLOW_ID(id)) {
 495                 ip6_sprintf(src, &id->src_ip6);
 496                 ip6_sprintf(dst, &id->dst_ip6);
 497         } else
 498 #endif
 499         {
 500                 da.s_addr = htonl(id->src_ip);
 501                 inet_ntop(AF_INET, &da, src, sizeof(src));
 502                 da.s_addr = htonl(id->dst_ip);
 503                 inet_ntop(AF_INET, &da, dst, sizeof(dst));
 504         }
 505         log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
 506             prefix, dyn_type, src, id->src_port, dst,
 507             id->dst_port, DYN_COUNT, postfix);
 508 }
 509
 510 #define print_dyn_rule(id, dtype, prefix, postfix)      \
 511         print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
 512
 513 #define TIME_LEQ(a,b)       ((int)((a)-(b)) <= 0)
 514 #define TIME_LE(a,b)       ((int)((a)-(b)) < 0)
 515
 516 static void
 517 dyn_update_proto_state(ipfw_dyn_rule *q, const struct ipfw_flow_id *id,
 518     const struct tcphdr *tcp, int dir)
 519 {
 520         uint32_t ack;
 521         u_char flags;
 522
 523         if (id->proto == IPPROTO_TCP) {
 524                 flags = id->_flags & (TH_FIN | TH_SYN | TH_RST);
 525 #define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
 526 #define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
 527 #define TCP_FLAGS       (TH_FLAGS | (TH_FLAGS << 8))
 528 #define ACK_FWD         0x10000                 /* fwd ack seen */
 529 #define ACK_REV         0x20000                 /* rev ack seen */
 530
 531                 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
 532                 switch (q->state & TCP_FLAGS) {
 533                 case TH_SYN:                    /* opening */
 534                         q->expire = time_uptime + V_dyn_syn_lifetime;
 535                         break;
 536
 537                 case BOTH_SYN:                  /* move to established */
 538                 case BOTH_SYN | TH_FIN:         /* one side tries to close */
 539                 case BOTH_SYN | (TH_FIN << 8):
 540 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
 541                         if (tcp == NULL)
 542                                 break;
 543
 544                         ack = ntohl(tcp->th_ack);
 545                         if (dir == MATCH_FORWARD) {
 546                                 if (q->ack_fwd == 0 ||
 547                                     _SEQ_GE(ack, q->ack_fwd)) {
 548                                         q->ack_fwd = ack;
 549                                         q->state |= ACK_FWD;
 550                                 }
 551                         } else {
 552                                 if (q->ack_rev == 0 ||
 553                                     _SEQ_GE(ack, q->ack_rev)) {
 554                                         q->ack_rev = ack;
 555                                         q->state |= ACK_REV;
 556                                 }
 557                         }
 558                         if ((q->state & (ACK_FWD | ACK_REV)) ==
 559                             (ACK_FWD | ACK_REV)) {
 560                                 q->expire = time_uptime + V_dyn_ack_lifetime;
 561                                 q->state &= ~(ACK_FWD | ACK_REV);
 562                         }
 563                         break;
 564
 565                 case BOTH_SYN | BOTH_FIN:       /* both sides closed */
 566                         if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
 567                                 V_dyn_fin_lifetime =
 568                                     V_dyn_keepalive_period - 1;
 569                         q->expire = time_uptime + V_dyn_fin_lifetime;
 570                         break;
 571
 572                 default:
 573 #if 0
 574                         /*
 575                          * reset or some invalid combination, but can also
 576                          * occur if we use keep-state the wrong way.
 577                          */
 578                         if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
 579                                 printf("invalid state: 0x%x\n", q->state);
 580 #endif
 581                         if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
 582                                 V_dyn_rst_lifetime =
 583                                     V_dyn_keepalive_period - 1;
 584                         q->expire = time_uptime + V_dyn_rst_lifetime;
 585                         break;
 586                 }
 587         } else if (id->proto == IPPROTO_UDP) {
 588                 q->expire = time_uptime + V_dyn_udp_lifetime;
 589         } else {
 590                 /* other protocols */
 591                 q->expire = time_uptime + V_dyn_short_lifetime;
 592         }
 593 }
 594
 595 /*
 596  * Lookup a dynamic rule, locked version.
 597  */
 598 static ipfw_dyn_rule *
 599 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
 600     struct tcphdr *tcp, uint16_t kidx)
 601 {
 602         /*
 603          * Stateful ipfw extensions.
 604          * Lookup into dynamic session queue.
 605          */
 606         ipfw_dyn_rule *prev, *q = NULL;
 607         int dir;
 608
 609         IPFW_BUCK_ASSERT(i);
 610
 611         dir = MATCH_NONE;
 612         for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
 613                 if (q->dyn_type == O_LIMIT_PARENT)
 614                         continue;
 615
 616                 if (pkt->proto != q->id.proto)
 617                         continue;
 618
 619                 if (kidx != 0 && kidx != q->kidx)
 620                         continue;
 621
 622                 if (IS_IP6_FLOW_ID(pkt)) {
 623                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
 624                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
 625                             pkt->src_port == q->id.src_port &&
 626                             pkt->dst_port == q->id.dst_port) {
 627                                 dir = MATCH_FORWARD;
 628                                 break;
 629                         }
 630                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
 631                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
 632                             pkt->src_port == q->id.dst_port &&
 633                             pkt->dst_port == q->id.src_port) {
 634                                 dir = MATCH_REVERSE;
 635                                 break;
 636                         }
 637                 } else {
 638                         if (pkt->src_ip == q->id.src_ip &&
 639                             pkt->dst_ip == q->id.dst_ip &&
 640                             pkt->src_port == q->id.src_port &&
 641                             pkt->dst_port == q->id.dst_port) {
 642                                 dir = MATCH_FORWARD;
 643                                 break;
 644                         }
 645                         if (pkt->src_ip == q->id.dst_ip &&
 646                             pkt->dst_ip == q->id.src_ip &&
 647                             pkt->src_port == q->id.dst_port &&
 648                             pkt->dst_port == q->id.src_port) {
 649                                 dir = MATCH_REVERSE;
 650                                 break;
 651                         }
 652                 }
 653         }
 654         if (q == NULL)
 655                 goto done;      /* q = NULL, not found */
 656
 657         if (prev != NULL) {     /* found and not in front */
 658                 prev->next = q->next;
 659                 q->next = V_ipfw_dyn_v[i].head;
 660                 V_ipfw_dyn_v[i].head = q;
 661         }
 662
 663         /* update state according to flags */
 664         dyn_update_proto_state(q, pkt, tcp, dir);
 665 done:
 666         if (match_direction != NULL)
 667                 *match_direction = dir;
 668         return (q);
 669 }
 670
 671 ipfw_dyn_rule *
 672 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
 673     struct tcphdr *tcp, uint16_t kidx)
 674 {
 675         ipfw_dyn_rule *q;
 676         int i;
 677
 678         i = hash_packet(pkt, V_curr_dyn_buckets);
 679
 680         IPFW_BUCK_LOCK(i);
 681         q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp, kidx);
 682         if (q == NULL)
 683                 IPFW_BUCK_UNLOCK(i);
 684         /* NB: return table locked when q is not NULL */
 685         return q;
 686 }
 687
 688 /*
 689  * Unlock bucket mtx
 690  * @p - pointer to dynamic rule
 691  */
 692 void
 693 ipfw_dyn_unlock(ipfw_dyn_rule *q)
 694 {
 695
 696         IPFW_BUCK_UNLOCK(q->bucket);
 697 }
 698
 699 static int
 700 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
 701 {
 702         int i, k, nbuckets_old;
 703         ipfw_dyn_rule *q;
 704         struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
 705
 706         /* Check if given number is power of 2 and less than 64k */
 707         if ((nbuckets > 65536) || (!powerof2(nbuckets)))
 708                 return 1;
 709
 710         CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
 711             V_curr_dyn_buckets, nbuckets);
 712
 713         /* Allocate and initialize new hash */
 714         dyn_v = malloc(nbuckets * sizeof(*dyn_v), M_IPFW,
 715             M_WAITOK | M_ZERO);
 716
 717         for (i = 0 ; i < nbuckets; i++)
 718                 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
 719
 720         /*
 721          * Call upper half lock, as get_map() do to ease
 722          * read-only access to dynamic rules hash from sysctl
 723          */
 724         IPFW_UH_WLOCK(chain);
 725
 726         /*
 727          * Acquire chain write lock to permit hash access
 728          * for main traffic path without additional locks
 729          */
 730         IPFW_WLOCK(chain);
 731
 732         /* Save old values */
 733         nbuckets_old = V_curr_dyn_buckets;
 734         dyn_v_old = V_ipfw_dyn_v;
 735
 736         /* Skip relinking if array is not set up */
 737         if (V_ipfw_dyn_v == NULL)
 738                 V_curr_dyn_buckets = 0;
 739
 740         /* Re-link all dynamic states */
 741         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
 742                 while (V_ipfw_dyn_v[i].head != NULL) {
 743                         /* Remove from current chain */
 744                         q = V_ipfw_dyn_v[i].head;
 745                         V_ipfw_dyn_v[i].head = q->next;
 746
 747                         /* Get new hash value */
 748                         k = hash_packet(&q->id, nbuckets);
 749                         q->bucket = k;
 750                         /* Add to the new head */
 751                         q->next = dyn_v[k].head;
 752                         dyn_v[k].head = q;
 753              }
 754         }
 755
 756         /* Update current pointers/buckets values */
 757         V_curr_dyn_buckets = nbuckets;
 758         V_ipfw_dyn_v = dyn_v;
 759
 760         IPFW_WUNLOCK(chain);
 761
 762         IPFW_UH_WUNLOCK(chain);
 763
 764         /* Start periodic callout on initial creation */
 765         if (dyn_v_old == NULL) {
 766                 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
 767                 return (0);
 768         }
 769
 770         /* Destroy all mutexes */
 771         for (i = 0 ; i < nbuckets_old ; i++)
 772                 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
 773
 774         /* Free old hash */
 775         free(dyn_v_old, M_IPFW);
 776
 777         return 0;
 778 }
 779
 780 /**
 781  * Install state of type 'type' for a dynamic session.
 782  * The hash table contains two type of rules:
 783  * - regular rules (O_KEEP_STATE)
 784  * - rules for sessions with limited number of sess per user
 785  *   (O_LIMIT). When they are created, the parent is
 786  *   increased by 1, and decreased on delete. In this case,
 787  *   the third parameter is the parent rule and not the chain.
 788  * - "parent" rules for the above (O_LIMIT_PARENT).
 789  */
 790 static ipfw_dyn_rule *
 791 add_dyn_rule(struct ipfw_flow_id *id, int i, uint8_t dyn_type,
 792     struct ip_fw *rule, uint16_t kidx)
 793 {
 794         ipfw_dyn_rule *r;
 795
 796         IPFW_BUCK_ASSERT(i);
 797
 798         r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
 799         if (r == NULL) {
 800                 if (last_log != time_uptime) {
 801                         last_log = time_uptime;
 802                         log(LOG_DEBUG,
 803                             "ipfw: Cannot allocate dynamic state, "
 804                             "consider increasing net.inet.ip.fw.dyn_max\n");
 805                 }
 806                 return NULL;
 807         }
 808         ipfw_dyn_count++;
 809
 810         /*
 811          * refcount on parent is already incremented, so
 812          * it is safe to use parent unlocked.
 813          */
 814         if (dyn_type == O_LIMIT) {
 815                 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
 816                 if ( parent->dyn_type != O_LIMIT_PARENT)
 817                         panic("invalid parent");
 818                 r->parent = parent;
 819                 rule = parent->rule;
 820         }
 821
 822         r->id = *id;
 823         r->expire = time_uptime + V_dyn_syn_lifetime;
 824         r->rule = rule;
 825         r->dyn_type = dyn_type;
 826         IPFW_ZERO_DYN_COUNTER(r);
 827         r->count = 0;
 828         r->kidx = kidx;
 829         r->bucket = i;
 830         r->next = V_ipfw_dyn_v[i].head;
 831         V_ipfw_dyn_v[i].head = r;
 832         DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
 833         return r;
 834 }
 835
 836 /**
 837  * lookup dynamic parent rule using pkt and rule as search keys.
 838  * If the lookup fails, then install one.
 839  */
 840 static ipfw_dyn_rule *
 841 lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule,
 842     uint16_t kidx)
 843 {
 844         ipfw_dyn_rule *q;
 845         int i, is_v6;
 846
 847         is_v6 = IS_IP6_FLOW_ID(pkt);
 848         i = hash_packet( pkt, V_curr_dyn_buckets );
 849         *pindex = i;
 850         IPFW_BUCK_LOCK(i);
 851         for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
 852                 if (q->dyn_type == O_LIMIT_PARENT &&
 853                     kidx == q->kidx &&
 854                     rule == q->rule &&
 855                     pkt->proto == q->id.proto &&
 856                     pkt->src_port == q->id.src_port &&
 857                     pkt->dst_port == q->id.dst_port &&
 858                     (
 859                         (is_v6 &&
 860                          IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
 861                                 &(q->id.src_ip6)) &&
 862                          IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
 863                                 &(q->id.dst_ip6))) ||
 864                         (!is_v6 &&
 865                          pkt->src_ip == q->id.src_ip &&
 866                          pkt->dst_ip == q->id.dst_ip)
 867                     )
 868                 ) {
 869                         q->expire = time_uptime + V_dyn_short_lifetime;
 870                         DEB(print_dyn_rule(pkt, q->dyn_type,
 871                             "lookup_dyn_parent found", "");)
 872                         return q;
 873                 }
 874
 875         /* Add virtual limiting rule */
 876         return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule, kidx);
 877 }
 878
 879 /**
 880  * Install dynamic state for rule type cmd->o.opcode
 881  *
 882  * Returns 1 (failure) if state is not installed because of errors or because
 883  * session limitations are enforced.
 884  */
 885 int
 886 ipfw_install_state(struct ip_fw_chain *chain, struct ip_fw *rule,
 887     ipfw_insn_limit *cmd, struct ip_fw_args *args, uint32_t tablearg)
 888 {
 889         ipfw_dyn_rule *q;
 890         int i;
 891
 892         DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state",
 893             (cmd->o.arg1 == 0 ? "": DYN_STATE_OBJ(chain, &cmd->o)->name));)
 894
 895         i = hash_packet(&args->f_id, V_curr_dyn_buckets);
 896
 897         IPFW_BUCK_LOCK(i);
 898
 899         q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL, cmd->o.arg1);
 900         if (q != NULL) {        /* should never occur */
 901                 DEB(
 902                 if (last_log != time_uptime) {
 903                         last_log = time_uptime;
 904                         printf("ipfw: %s: entry already present, done\n",
 905                             __func__);
 906                 })
 907                 IPFW_BUCK_UNLOCK(i);
 908                 return (0);
 909         }
 910
 911         /*
 912          * State limiting is done via uma(9) zone limiting.
 913          * Save pointer to newly-installed rule and reject
 914          * packet if add_dyn_rule() returned NULL.
 915          * Note q is currently set to NULL.
 916          */
 917
 918         switch (cmd->o.opcode) {
 919         case O_KEEP_STATE:      /* bidir rule */
 920                 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule,
 921                     cmd->o.arg1);
 922                 break;
 923
 924         case O_LIMIT: {         /* limit number of sessions */
 925                 struct ipfw_flow_id id;
 926                 ipfw_dyn_rule *parent;
 927                 uint32_t conn_limit;
 928                 uint16_t limit_mask = cmd->limit_mask;
 929                 int pindex;
 930
 931                 conn_limit = IP_FW_ARG_TABLEARG(chain, cmd->conn_limit, limit);
 932
 933                 DEB(
 934                 if (cmd->conn_limit == IP_FW_TARG)
 935                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
 936                             "(tablearg)\n", __func__, conn_limit);
 937                 else
 938                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
 939                             __func__, conn_limit);
 940                 )
 941
 942                 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
 943                 id.proto = args->f_id.proto;
 944                 id.addr_type = args->f_id.addr_type;
 945                 id.fib = M_GETFIB(args->m);
 946
 947                 if (IS_IP6_FLOW_ID (&(args->f_id))) {
 948                         bzero(&id.src_ip6, sizeof(id.src_ip6));
 949                         bzero(&id.dst_ip6, sizeof(id.dst_ip6));
 950
 951                         if (limit_mask & DYN_SRC_ADDR)
 952                                 id.src_ip6 = args->f_id.src_ip6;
 953                         if (limit_mask & DYN_DST_ADDR)
 954                                 id.dst_ip6 = args->f_id.dst_ip6;
 955                 } else {
 956                         if (limit_mask & DYN_SRC_ADDR)
 957                                 id.src_ip = args->f_id.src_ip;
 958                         if (limit_mask & DYN_DST_ADDR)
 959                                 id.dst_ip = args->f_id.dst_ip;
 960                 }
 961                 if (limit_mask & DYN_SRC_PORT)
 962                         id.src_port = args->f_id.src_port;
 963                 if (limit_mask & DYN_DST_PORT)
 964                         id.dst_port = args->f_id.dst_port;
 965
 966                 /*
 967                  * We have to release lock for previous bucket to
 968                  * avoid possible deadlock
 969                  */
 970                 IPFW_BUCK_UNLOCK(i);
 971
 972                 parent = lookup_dyn_parent(&id, &pindex, rule, cmd->o.arg1);
 973                 if (parent == NULL) {
 974                         printf("ipfw: %s: add parent failed\n", __func__);
 975                         IPFW_BUCK_UNLOCK(pindex);
 976                         return (1);
 977                 }
 978
 979                 if (parent->count >= conn_limit) {
 980                         if (V_fw_verbose && last_log != time_uptime) {
 981                                 char sbuf[24];
 982                                 last_log = time_uptime;
 983                                 snprintf(sbuf, sizeof(sbuf),
 984                                     "%d drop session",
 985                                     parent->rule->rulenum);
 986                                 print_dyn_rule_flags(&args->f_id,
 987                                     cmd->o.opcode,
 988                                     LOG_SECURITY | LOG_DEBUG,
 989                                     sbuf, "too many entries");
 990                         }
 991                         IPFW_BUCK_UNLOCK(pindex);
 992                         return (1);
 993                 }
 994                 /* Increment counter on parent */
 995                 parent->count++;
 996                 IPFW_BUCK_UNLOCK(pindex);
 997
 998                 IPFW_BUCK_LOCK(i);
 999                 q = add_dyn_rule(&args->f_id, i, O_LIMIT,
1000                     (struct ip_fw *)parent, cmd->o.arg1);
1001                 if (q == NULL) {
1002                         /* Decrement index and notify caller */
1003                         IPFW_BUCK_UNLOCK(i);
1004                         IPFW_BUCK_LOCK(pindex);
1005                         parent->count--;
1006                         IPFW_BUCK_UNLOCK(pindex);
1007                         return (1);
1008                 }
1009                 break;
1010         }
1011         default:
1012                 printf("ipfw: %s: unknown dynamic rule type %u\n",
1013                     __func__, cmd->o.opcode);
1014         }
1015
1016         if (q == NULL) {
1017                 IPFW_BUCK_UNLOCK(i);
1018                 return (1);     /* Notify caller about failure */
1019         }
1020
1021         dyn_update_proto_state(q, &args->f_id, NULL, MATCH_FORWARD);
1022         IPFW_BUCK_UNLOCK(i);
1023         return (0);
1024 }
1025
1026 /*
1027  * Generate a TCP packet, containing either a RST or a keepalive.
1028  * When flags & TH_RST, we are sending a RST packet, because of a
1029  * "reset" action matched the packet.
1030  * Otherwise we are sending a keepalive, and flags & TH_
1031  * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
1032  * so that MAC can label the reply appropriately.
1033  */
1034 struct mbuf *
1035 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
1036     u_int32_t ack, int flags)
1037 {
1038         struct mbuf *m = NULL;          /* stupid compiler */
1039         int len, dir;
1040         struct ip *h = NULL;            /* stupid compiler */
1041 #ifdef INET6
1042         struct ip6_hdr *h6 = NULL;
1043 #endif
1044         struct tcphdr *th = NULL;
1045
1046         MGETHDR(m, M_NOWAIT, MT_DATA);
1047         if (m == NULL)
1048                 return (NULL);
1049
1050         M_SETFIB(m, id->fib);
1051 #ifdef MAC
1052         if (replyto != NULL)
1053                 mac_netinet_firewall_reply(replyto, m);
1054         else
1055                 mac_netinet_firewall_send(m);
1056 #else
1057         (void)replyto;          /* don't warn about unused arg */
1058 #endif
1059
1060         switch (id->addr_type) {
1061         case 4:
1062                 len = sizeof(struct ip) + sizeof(struct tcphdr);
1063                 break;
1064 #ifdef INET6
1065         case 6:
1066                 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1067                 break;
1068 #endif
1069         default:
1070                 /* XXX: log me?!? */
1071                 FREE_PKT(m);
1072                 return (NULL);
1073         }
1074         dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
1075
1076         m->m_data += max_linkhdr;
1077         m->m_flags |= M_SKIP_FIREWALL;
1078         m->m_pkthdr.len = m->m_len = len;
1079         m->m_pkthdr.rcvif = NULL;
1080         bzero(m->m_data, len);
1081
1082         switch (id->addr_type) {
1083         case 4:
1084                 h = mtod(m, struct ip *);
1085
1086                 /* prepare for checksum */
1087                 h->ip_p = IPPROTO_TCP;
1088                 h->ip_len = htons(sizeof(struct tcphdr));
1089                 if (dir) {
1090                         h->ip_src.s_addr = htonl(id->src_ip);
1091                         h->ip_dst.s_addr = htonl(id->dst_ip);
1092                 } else {
1093                         h->ip_src.s_addr = htonl(id->dst_ip);
1094                         h->ip_dst.s_addr = htonl(id->src_ip);
1095                 }
1096
1097                 th = (struct tcphdr *)(h + 1);
1098                 break;
1099 #ifdef INET6
1100         case 6:
1101                 h6 = mtod(m, struct ip6_hdr *);
1102
1103                 /* prepare for checksum */
1104                 h6->ip6_nxt = IPPROTO_TCP;
1105                 h6->ip6_plen = htons(sizeof(struct tcphdr));
1106                 if (dir) {
1107                         h6->ip6_src = id->src_ip6;
1108                         h6->ip6_dst = id->dst_ip6;
1109                 } else {
1110                         h6->ip6_src = id->dst_ip6;
1111                         h6->ip6_dst = id->src_ip6;
1112                 }
1113
1114                 th = (struct tcphdr *)(h6 + 1);
1115                 break;
1116 #endif
1117         }
1118
1119         if (dir) {
1120                 th->th_sport = htons(id->src_port);
1121                 th->th_dport = htons(id->dst_port);
1122         } else {
1123                 th->th_sport = htons(id->dst_port);
1124                 th->th_dport = htons(id->src_port);
1125         }
1126         th->th_off = sizeof(struct tcphdr) >> 2;
1127
1128         if (flags & TH_RST) {
1129                 if (flags & TH_ACK) {
1130                         th->th_seq = htonl(ack);
1131                         th->th_flags = TH_RST;
1132                 } else {
1133                         if (flags & TH_SYN)
1134                                 seq++;
1135                         th->th_ack = htonl(seq);
1136                         th->th_flags = TH_RST | TH_ACK;
1137                 }
1138         } else {
1139                 /*
1140                  * Keepalive - use caller provided sequence numbers
1141                  */
1142                 th->th_seq = htonl(seq);
1143                 th->th_ack = htonl(ack);
1144                 th->th_flags = TH_ACK;
1145         }
1146
1147         switch (id->addr_type) {
1148         case 4:
1149                 th->th_sum = in_cksum(m, len);
1150
1151                 /* finish the ip header */
1152                 h->ip_v = 4;
1153                 h->ip_hl = sizeof(*h) >> 2;
1154                 h->ip_tos = IPTOS_LOWDELAY;
1155                 h->ip_off = htons(0);
1156                 h->ip_len = htons(len);
1157                 h->ip_ttl = V_ip_defttl;
1158                 h->ip_sum = 0;
1159                 break;
1160 #ifdef INET6
1161         case 6:
1162                 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
1163                     sizeof(struct tcphdr));
1164
1165                 /* finish the ip6 header */
1166                 h6->ip6_vfc |= IPV6_VERSION;
1167                 h6->ip6_hlim = IPV6_DEFHLIM;
1168                 break;
1169 #endif
1170         }
1171
1172         return (m);
1173 }
1174
1175 /*
1176  * Queue keepalive packets for given dynamic rule
1177  */
1178 static struct mbuf **
1179 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
1180 {
1181         struct mbuf *m_rev, *m_fwd;
1182
1183         m_rev = (q->state & ACK_REV) ? NULL :
1184             ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
1185         m_fwd = (q->state & ACK_FWD) ? NULL :
1186             ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
1187
1188         if (m_rev != NULL) {
1189                 *mtailp = m_rev;
1190                 mtailp = &(*mtailp)->m_nextpkt;
1191         }
1192         if (m_fwd != NULL) {
1193                 *mtailp = m_fwd;
1194                 mtailp = &(*mtailp)->m_nextpkt;
1195         }
1196
1197         return (mtailp);
1198 }
1199
1200 /*
1201  * This procedure is used to perform various maintenance
1202  * on dynamic hash list. Currently it is called every second.
1203  */
1204 static void
1205 ipfw_dyn_tick(void * vnetx)
1206 {
1207         struct ip_fw_chain *chain;
1208         int check_ka = 0;
1209 #ifdef VIMAGE
1210         struct vnet *vp = vnetx;
1211 #endif
1212
1213         CURVNET_SET(vp);
1214
1215         chain = &V_layer3_chain;
1216
1217         /* Run keepalive checks every keepalive_period iff ka is enabled */
1218         if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
1219             (V_dyn_keepalive != 0)) {
1220                 V_dyn_keepalive_last = time_uptime;
1221                 check_ka = 1;
1222         }
1223
1224         check_dyn_rules(chain, NULL, check_ka, 1);
1225
1226         callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
1227
1228         CURVNET_RESTORE();
1229 }
1230
1231
1232 /*
1233  * Walk through all dynamic states doing generic maintenance:
1234  * 1) free expired states
1235  * 2) free all states based on deleted rule / set
1236  * 3) send keepalives for states if needed
1237  *
1238  * @chain - pointer to current ipfw rules chain
1239  * @rule - delete all states originated by given rule if != NULL
1240  * @set - delete all states originated by any rule in set @set if != RESVD_SET
1241  * @check_ka - perform checking/sending keepalives
1242  * @timer - indicate call from timer routine.
1243  *
1244  * Timer routine must call this function unlocked to permit
1245  * sending keepalives/resizing table.
1246  *
1247  * Others has to call function with IPFW_UH_WLOCK held.
1248  * Additionally, function assume that dynamic rule/set is
1249  * ALREADY deleted so no new states can be generated by
1250  * 'deleted' rules.
1251  *
1252  * Write lock is needed to ensure that unused parent rules
1253  * are not freed by other instance (see stage 2, 3)
1254  */
1255 static void
1256 check_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt,
1257     int check_ka, int timer)
1258 {
1259         struct mbuf *m0, *m, *mnext, **mtailp;
1260         struct ip *h;
1261         int i, dyn_count, new_buckets = 0, max_buckets;
1262         int expired = 0, expired_limits = 0, parents = 0, total = 0;
1263         ipfw_dyn_rule *q, *q_prev, *q_next;
1264         ipfw_dyn_rule *exp_head, **exptailp;
1265         ipfw_dyn_rule *exp_lhead, **expltailp;
1266
1267         KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1268             __func__));
1269
1270         /* Avoid possible LOR */
1271         KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1272             __func__));
1273
1274         /*
1275          * Do not perform any checks if we currently have no dynamic states
1276          */
1277         if (DYN_COUNT == 0)
1278                 return;
1279
1280         /* Expired states */
1281         exp_head = NULL;
1282         exptailp = &exp_head;
1283
1284         /* Expired limit states */
1285         exp_lhead = NULL;
1286         expltailp = &exp_lhead;
1287
1288         /*
1289          * We make a chain of packets to go out here -- not deferring
1290          * until after we drop the IPFW dynamic rule lock would result
1291          * in a lock order reversal with the normal packet input -> ipfw
1292          * call stack.
1293          */
1294         m0 = NULL;
1295         mtailp = &m0;
1296
1297         /* Protect from hash resizing */
1298         if (timer != 0)
1299                 IPFW_UH_WLOCK(chain);
1300         else
1301                 IPFW_UH_WLOCK_ASSERT(chain);
1302
1303 #define NEXT_RULE()     { q_prev = q; q = q->next ; continue; }
1304
1305         /* Stage 1: perform requested deletion */
1306         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1307                 IPFW_BUCK_LOCK(i);
1308                 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1309                         /* account every rule */
1310                         total++;
1311
1312                         /* Skip parent rules at all */
1313                         if (q->dyn_type == O_LIMIT_PARENT) {
1314                                 parents++;
1315                                 NEXT_RULE();
1316                         }
1317
1318                         /*
1319                          * Remove rules which are:
1320                          * 1) expired
1321                          * 2) matches deletion range
1322                          */
1323                         if ((TIME_LEQ(q->expire, time_uptime)) ||
1324                             (rt != NULL && ipfw_match_range(q->rule, rt))) {
1325                                 if (TIME_LE(time_uptime, q->expire) &&
1326                                     q->dyn_type == O_KEEP_STATE &&
1327                                     V_dyn_keep_states != 0) {
1328                                         /*
1329                                          * Do not delete state if
1330                                          * it is not expired and
1331                                          * dyn_keep_states is ON.
1332                                          * However we need to re-link it
1333                                          * to any other stable rule
1334                                          */
1335                                         q->rule = chain->default_rule;
1336                                         NEXT_RULE();
1337                                 }
1338
1339                                 /* Unlink q from current list */
1340                                 q_next = q->next;
1341                                 if (q == V_ipfw_dyn_v[i].head)
1342                                         V_ipfw_dyn_v[i].head = q_next;
1343                                 else
1344                                         q_prev->next = q_next;
1345
1346                                 q->next = NULL;
1347
1348                                 /* queue q to expire list */
1349                                 if (q->dyn_type != O_LIMIT) {
1350                                         *exptailp = q;
1351                                         exptailp = &(*exptailp)->next;
1352                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1353                                             "unlink entry", "left");
1354                                         )
1355                                 } else {
1356                                         /* Separate list for limit rules */
1357                                         *expltailp = q;
1358                                         expltailp = &(*expltailp)->next;
1359                                         expired_limits++;
1360                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1361                                             "unlink limit entry", "left");
1362                                         )
1363                                 }
1364
1365                                 q = q_next;
1366                                 expired++;
1367                                 continue;
1368                         }
1369
1370                         /*
1371                          * Check if we need to send keepalive:
1372                          * we need to ensure if is time to do KA,
1373                          * this is established TCP session, and
1374                          * expire time is within keepalive interval
1375                          */
1376                         if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1377                             ((q->state & BOTH_SYN) == BOTH_SYN) &&
1378                             (TIME_LEQ(q->expire, time_uptime +
1379                               V_dyn_keepalive_interval)))
1380                                 mtailp = ipfw_dyn_send_ka(mtailp, q);
1381
1382                         NEXT_RULE();
1383                 }
1384                 IPFW_BUCK_UNLOCK(i);
1385         }
1386
1387         /* Stage 2: decrement counters from O_LIMIT parents */
1388         if (expired_limits != 0) {
1389                 /*
1390                  * XXX: Note that deleting set with more than one
1391                  * heavily-used LIMIT rules can result in overwhelming
1392                  * locking due to lack of per-hash value sorting
1393                  *
1394                  * We should probably think about:
1395                  * 1) pre-allocating hash of size, say,
1396                  * MAX(16, V_curr_dyn_buckets / 1024)
1397                  * 2) checking if expired_limits is large enough
1398                  * 3) If yes, init hash (or its part), re-link
1399                  * current list and start decrementing procedure in
1400                  * each bucket separately
1401                  */
1402
1403                 /*
1404                  * Small optimization: do not unlock bucket until
1405                  * we see the next item resides in different bucket
1406                  */
1407                 if (exp_lhead != NULL) {
1408                         i = exp_lhead->parent->bucket;
1409                         IPFW_BUCK_LOCK(i);
1410                 }
1411                 for (q = exp_lhead; q != NULL; q = q->next) {
1412                         if (i != q->parent->bucket) {
1413                                 IPFW_BUCK_UNLOCK(i);
1414                                 i = q->parent->bucket;
1415                                 IPFW_BUCK_LOCK(i);
1416                         }
1417
1418                         /* Decrease parent refcount */
1419                         q->parent->count--;
1420                 }
1421                 if (exp_lhead != NULL)
1422                         IPFW_BUCK_UNLOCK(i);
1423         }
1424
1425         /*
1426          * We protectet ourselves from unused parent deletion
1427          * (from the timer function) by holding UH write lock.
1428          */
1429
1430         /* Stage 3: remove unused parent rules */
1431         if ((parents != 0) && (expired != 0)) {
1432                 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1433                         IPFW_BUCK_LOCK(i);
1434                         for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1435                                 if (q->dyn_type != O_LIMIT_PARENT)
1436                                         NEXT_RULE();
1437
1438                                 if (q->count != 0)
1439                                         NEXT_RULE();
1440
1441                                 /* Parent rule without consumers */
1442
1443                                 /* Unlink q from current list */
1444                                 q_next = q->next;
1445                                 if (q == V_ipfw_dyn_v[i].head)
1446                                         V_ipfw_dyn_v[i].head = q_next;
1447                                 else
1448                                         q_prev->next = q_next;
1449
1450                                 q->next = NULL;
1451
1452                                 /* Add to expired list */
1453                                 *exptailp = q;
1454                                 exptailp = &(*exptailp)->next;
1455
1456                                 DEB(print_dyn_rule(&q->id, q->dyn_type,
1457                                     "unlink parent entry", "left");
1458                                 )
1459
1460                                 expired++;
1461
1462                                 q = q_next;
1463                         }
1464                         IPFW_BUCK_UNLOCK(i);
1465                 }
1466         }
1467
1468 #undef NEXT_RULE
1469
1470         if (timer != 0) {
1471                 /*
1472                  * Check if we need to resize hash:
1473                  * if current number of states exceeds number of buckes in hash,
1474                  * grow hash size to the minimum power of 2 which is bigger than
1475                  * current states count. Limit hash size by 64k.
1476                  */
1477                 max_buckets = (V_dyn_buckets_max > 65536) ?
1478                     65536 : V_dyn_buckets_max;
1479
1480                 dyn_count = DYN_COUNT;
1481
1482                 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1483                     (dyn_count < max_buckets)) {
1484                         new_buckets = V_curr_dyn_buckets;
1485                         while (new_buckets < dyn_count) {
1486                                 new_buckets *= 2;
1487
1488                                 if (new_buckets >= max_buckets)
1489                                         break;
1490                         }
1491                 }
1492
1493                 IPFW_UH_WUNLOCK(chain);
1494         }
1495
1496         /* Finally delete old states ad limits if any */
1497         for (q = exp_head; q != NULL; q = q_next) {
1498                 q_next = q->next;
1499                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1500                 ipfw_dyn_count--;
1501         }
1502
1503         for (q = exp_lhead; q != NULL; q = q_next) {
1504                 q_next = q->next;
1505                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1506                 ipfw_dyn_count--;
1507         }
1508
1509         /*
1510          * The rest code MUST be called from timer routine only
1511          * without holding any locks
1512          */
1513         if (timer == 0)
1514                 return;
1515
1516         /* Send keepalive packets if any */
1517         for (m = m0; m != NULL; m = mnext) {
1518                 mnext = m->m_nextpkt;
1519                 m->m_nextpkt = NULL;
1520                 h = mtod(m, struct ip *);
1521                 if (h->ip_v == 4)
1522                         ip_output(m, NULL, NULL, 0, NULL, NULL);
1523 #ifdef INET6
1524                 else
1525                         ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1526 #endif
1527         }
1528
1529         /* Run table resize without holding any locks */
1530         if (new_buckets != 0)
1531                 resize_dynamic_table(chain, new_buckets);
1532 }
1533
1534 /*
1535  * Deletes all dynamic rules originated by given rule or all rules in
1536  * given set. Specify RESVD_SET to indicate set should not be used.
1537  * @chain - pointer to current ipfw rules chain
1538  * @rr - delete all states originated by rules in matched range.
1539  *
1540  * Function has to be called with IPFW_UH_WLOCK held.
1541  * Additionally, function assume that dynamic rule/set is
1542  * ALREADY deleted so no new states can be generated by
1543  * 'deleted' rules.
1544  */
1545 void
1546 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt)
1547 {
1548
1549         check_dyn_rules(chain, rt, 0, 0);
1550 }
1551
1552 /*
1553  * Check if rule contains at least one dynamic opcode.
1554  *
1555  * Returns 1 if such opcode is found, 0 otherwise.
1556  */
1557 int
1558 ipfw_is_dyn_rule(struct ip_fw *rule)
1559 {
1560         int cmdlen, l;
1561         ipfw_insn *cmd;
1562
1563         l = rule->cmd_len;
1564         cmd = rule->cmd;
1565         cmdlen = 0;
1566         for ( ; l > 0 ; l -= cmdlen, cmd += cmdlen) {
1567                 cmdlen = F_LEN(cmd);
1568
1569                 switch (cmd->opcode) {
1570                 case O_LIMIT:
1571                 case O_KEEP_STATE:
1572                 case O_PROBE_STATE:
1573                 case O_CHECK_STATE:
1574                         return (1);
1575                 }
1576         }
1577
1578         return (0);
1579 }
1580
1581 void
1582 ipfw_dyn_init(struct ip_fw_chain *chain)
1583 {
1584
1585         V_ipfw_dyn_v = NULL;
1586         V_dyn_buckets_max = 256; /* must be power of 2 */
1587         V_curr_dyn_buckets = 256; /* must be power of 2 */
1588
1589         V_dyn_ack_lifetime = 300;
1590         V_dyn_syn_lifetime = 20;
1591         V_dyn_fin_lifetime = 1;
1592         V_dyn_rst_lifetime = 1;
1593         V_dyn_udp_lifetime = 10;
1594         V_dyn_short_lifetime = 5;
1595
1596         V_dyn_keepalive_interval = 20;
1597         V_dyn_keepalive_period = 5;
1598         V_dyn_keepalive = 1;    /* do send keepalives */
1599         V_dyn_keepalive_last = time_uptime;
1600
1601         V_dyn_max = 16384; /* max # of dynamic rules */
1602
1603         V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1604             sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1605             UMA_ALIGN_PTR, 0);
1606
1607         /* Enforce limit on dynamic rules */
1608         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1609
1610         callout_init(&V_ipfw_timeout, 1);
1611
1612         /*
1613          * This can potentially be done on first dynamic rule
1614          * being added to chain.
1615          */
1616         resize_dynamic_table(chain, V_curr_dyn_buckets);
1617         IPFW_ADD_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes);
1618 }
1619
1620 void
1621 ipfw_dyn_uninit(int pass)
1622 {
1623         int i;
1624
1625         if (pass == 0) {
1626                 callout_drain(&V_ipfw_timeout);
1627                 return;
1628         }
1629         IPFW_DEL_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes);
1630
1631         if (V_ipfw_dyn_v != NULL) {
1632                 /*
1633                  * Skip deleting all dynamic states -
1634                  * uma_zdestroy() does this more efficiently;
1635                  */
1636
1637                 /* Destroy all mutexes */
1638                 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1639                         IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1640                 free(V_ipfw_dyn_v, M_IPFW);
1641                 V_ipfw_dyn_v = NULL;
1642         }
1643
1644         uma_zdestroy(V_ipfw_dyn_rule_zone);
1645 }
1646
1647 #ifdef SYSCTL_NODE
1648 /*
1649  * Get/set maximum number of dynamic states in given VNET instance.
1650  */
1651 static int
1652 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1653 {
1654         int error;
1655         unsigned int nstates;
1656
1657         nstates = V_dyn_max;
1658
1659         error = sysctl_handle_int(oidp, &nstates, 0, req);
1660         /* Read operation or some error */
1661         if ((error != 0) || (req->newptr == NULL))
1662                 return (error);
1663
1664         V_dyn_max = nstates;
1665         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1666
1667         return (0);
1668 }
1669
1670 /*
1671  * Get current number of dynamic states in given VNET instance.
1672  */
1673 static int
1674 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1675 {
1676         int error;
1677         unsigned int nstates;
1678
1679         nstates = DYN_COUNT;
1680
1681         error = sysctl_handle_int(oidp, &nstates, 0, req);
1682
1683         return (error);
1684 }
1685 #endif
1686
1687 /*
1688  * Returns size of dynamic states in legacy format
1689  */
1690 int
1691 ipfw_dyn_len(void)
1692 {
1693
1694         return (V_ipfw_dyn_v == NULL) ? 0 :
1695                 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1696 }
1697
1698 /*
1699  * Returns number of dynamic states.
1700  * Used by dump format v1 (current).
1701  */
1702 int
1703 ipfw_dyn_get_count(void)
1704 {
1705
1706         return (V_ipfw_dyn_v == NULL) ? 0 : DYN_COUNT;
1707 }
1708
1709 static void
1710 export_dyn_rule(ipfw_dyn_rule *src, ipfw_dyn_rule *dst)
1711 {
1712         uint16_t rulenum;
1713
1714         rulenum = (uint16_t)src->rule->rulenum;
1715         memcpy(dst, src, sizeof(*src));
1716         memcpy(&dst->rule, &rulenum, sizeof(rulenum));
1717         /*
1718          * store set number into high word of
1719          * dst->rule pointer.
1720          */
1721         memcpy((char *)&dst->rule + sizeof(rulenum), &src->rule->set,
1722             sizeof(src->rule->set));
1723         /*
1724          * store a non-null value in "next".
1725          * The userland code will interpret a
1726          * NULL here as a marker
1727          * for the last dynamic rule.
1728          */
1729         memcpy(&dst->next, &dst, sizeof(dst));
1730         dst->expire = TIME_LEQ(dst->expire, time_uptime) ?  0:
1731             dst->expire - time_uptime;
1732 }
1733
1734 /*
1735  * Fills int buffer given by @sd with dynamic states.
1736  * Used by dump format v1 (current).
1737  *
1738  * Returns 0 on success.
1739  */
1740 int
1741 ipfw_dump_states(struct ip_fw_chain *chain, struct sockopt_data *sd)
1742 {
1743         ipfw_dyn_rule *p;
1744         ipfw_obj_dyntlv *dst, *last;
1745         ipfw_obj_ctlv *ctlv;
1746         int i;
1747         size_t sz;
1748
1749         if (V_ipfw_dyn_v == NULL)
1750                 return (0);
1751
1752         IPFW_UH_RLOCK_ASSERT(chain);
1753
1754         ctlv = (ipfw_obj_ctlv *)ipfw_get_sopt_space(sd, sizeof(*ctlv));
1755         if (ctlv == NULL)
1756                 return (ENOMEM);
1757         sz = sizeof(ipfw_obj_dyntlv);
1758         ctlv->head.type = IPFW_TLV_DYNSTATE_LIST;
1759         ctlv->objsize = sz;
1760         last = NULL;
1761
1762         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1763                 IPFW_BUCK_LOCK(i);
1764                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1765                         dst = (ipfw_obj_dyntlv *)ipfw_get_sopt_space(sd, sz);
1766                         if (dst == NULL) {
1767                                 IPFW_BUCK_UNLOCK(i);
1768                                 return (ENOMEM);
1769                         }
1770
1771                         export_dyn_rule(p, &dst->state);
1772                         dst->head.length = sz;
1773                         dst->head.type = IPFW_TLV_DYN_ENT;
1774                         last = dst;
1775                 }
1776                 IPFW_BUCK_UNLOCK(i);
1777         }
1778
1779         if (last != NULL) /* mark last dynamic rule */
1780                 last->head.flags = IPFW_DF_LAST;
1781
1782         return (0);
1783 }
1784
1785 /*
1786  * Fill given buffer with dynamic states (legacy format).
1787  * IPFW_UH_RLOCK has to be held while calling.
1788  */
1789 void
1790 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1791 {
1792         ipfw_dyn_rule *p, *last = NULL;
1793         char *bp;
1794         int i;
1795
1796         if (V_ipfw_dyn_v == NULL)
1797                 return;
1798         bp = *pbp;
1799
1800         IPFW_UH_RLOCK_ASSERT(chain);
1801
1802         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1803                 IPFW_BUCK_LOCK(i);
1804                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1805                         if (bp + sizeof *p <= ep) {
1806                                 ipfw_dyn_rule *dst =
1807                                         (ipfw_dyn_rule *)bp;
1808
1809                                 export_dyn_rule(p, dst);
1810                                 last = dst;
1811                                 bp += sizeof(ipfw_dyn_rule);
1812                         }
1813                 }
1814                 IPFW_BUCK_UNLOCK(i);
1815         }
1816
1817         if (last != NULL) /* mark last dynamic rule */
1818                 bzero(&last->next, sizeof(last));
1819         *pbp = bp;
1820 }
1821 /* end of file */