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(const 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(const struct ipfw_flow_id *id, int buckets)
 272 {
 273         u_int32_t i;
 274
 275 #ifdef INET6
 276         if (IS_IP6_FLOW_ID(id))
 277                 i = hash_packet6(id);
 278         else
 279 #endif /* INET6 */
 280         i = (id->dst_ip) ^ (id->src_ip);
 281         i ^= (id->dst_port) ^ (id->src_port);
 282         return (i & (buckets - 1));
 283 }
 284
 285 #if 0
 286 #define DYN_DEBUG(fmt, ...)     do {                    \
 287         printf("%s: " fmt "\n", __func__, __VA_ARGS__); \
 288 } while (0)
 289 #else
 290 #define DYN_DEBUG(fmt, ...)
 291 #endif
 292
 293 static char *default_state_name = "default";
 294 struct dyn_state_obj {
 295         struct named_object     no;
 296         char                    name[64];
 297 };
 298
 299 #define DYN_STATE_OBJ(ch, cmd)  \
 300     ((struct dyn_state_obj *)SRV_OBJECT(ch, (cmd)->arg1))
 301 /*
 302  * Classifier callback.
 303  * Return 0 if opcode contains object that should be referenced
 304  * or rewritten.
 305  */
 306 static int
 307 dyn_classify(ipfw_insn *cmd, uint16_t *puidx, uint8_t *ptype)
 308 {
 309
 310         DYN_DEBUG("opcode %d, arg1 %d", cmd->opcode, cmd->arg1);
 311         /* Don't rewrite "check-state any" */
 312         if (cmd->arg1 == 0 &&
 313             cmd->opcode == O_CHECK_STATE)
 314                 return (1);
 315
 316         *puidx = cmd->arg1;
 317         *ptype = 0;
 318         return (0);
 319 }
 320
 321 static void
 322 dyn_update(ipfw_insn *cmd, uint16_t idx)
 323 {
 324
 325         cmd->arg1 = idx;
 326         DYN_DEBUG("opcode %d, arg1 %d", cmd->opcode, cmd->arg1);
 327 }
 328
 329 static int
 330 dyn_findbyname(struct ip_fw_chain *ch, struct tid_info *ti,
 331     struct named_object **pno)
 332 {
 333         ipfw_obj_ntlv *ntlv;
 334         const char *name;
 335
 336         DYN_DEBUG("uidx %d", ti->uidx);
 337         if (ti->uidx != 0) {
 338                 if (ti->tlvs == NULL)
 339                         return (EINVAL);
 340                 /* Search ntlv in the buffer provided by user */
 341                 ntlv = ipfw_find_name_tlv_type(ti->tlvs, ti->tlen, ti->uidx,
 342                     IPFW_TLV_STATE_NAME);
 343                 if (ntlv == NULL)
 344                         return (EINVAL);
 345                 name = ntlv->name;
 346         } else
 347                 name = default_state_name;
 348         /*
 349          * Search named object with corresponding name.
 350          * Since states objects are global - ignore the set value
 351          * and use zero instead.
 352          */
 353         *pno = ipfw_objhash_lookup_name_type(CHAIN_TO_SRV(ch), 0,
 354             IPFW_TLV_STATE_NAME, name);
 355         /*
 356          * We always return success here.
 357          * The caller will check *pno and mark object as unresolved,
 358          * then it will automatically create "default" object.
 359          */
 360         return (0);
 361 }
 362
 363 static struct named_object *
 364 dyn_findbykidx(struct ip_fw_chain *ch, uint16_t idx)
 365 {
 366
 367         DYN_DEBUG("kidx %d", idx);
 368         return (ipfw_objhash_lookup_kidx(CHAIN_TO_SRV(ch), idx));
 369 }
 370
 371 static int
 372 dyn_create(struct ip_fw_chain *ch, struct tid_info *ti,
 373     uint16_t *pkidx)
 374 {
 375         struct namedobj_instance *ni;
 376         struct dyn_state_obj *obj;
 377         struct named_object *no;
 378         ipfw_obj_ntlv *ntlv;
 379         char *name;
 380
 381         DYN_DEBUG("uidx %d", ti->uidx);
 382         if (ti->uidx != 0) {
 383                 if (ti->tlvs == NULL)
 384                         return (EINVAL);
 385                 ntlv = ipfw_find_name_tlv_type(ti->tlvs, ti->tlen, ti->uidx,
 386                     IPFW_TLV_STATE_NAME);
 387                 if (ntlv == NULL)
 388                         return (EINVAL);
 389                 name = ntlv->name;
 390         } else
 391                 name = default_state_name;
 392
 393         ni = CHAIN_TO_SRV(ch);
 394         obj = malloc(sizeof(*obj), M_IPFW, M_WAITOK | M_ZERO);
 395         obj->no.name = obj->name;
 396         obj->no.etlv = IPFW_TLV_STATE_NAME;
 397         strlcpy(obj->name, name, sizeof(obj->name));
 398
 399         IPFW_UH_WLOCK(ch);
 400         no = ipfw_objhash_lookup_name_type(ni, 0,
 401             IPFW_TLV_STATE_NAME, name);
 402         if (no != NULL) {
 403                 /*
 404                  * Object is already created.
 405                  * Just return its kidx and bump refcount.
 406                  */
 407                 *pkidx = no->kidx;
 408                 no->refcnt++;
 409                 IPFW_UH_WUNLOCK(ch);
 410                 free(obj, M_IPFW);
 411                 DYN_DEBUG("\tfound kidx %d", *pkidx);
 412                 return (0);
 413         }
 414         if (ipfw_objhash_alloc_idx(ni, &obj->no.kidx) != 0) {
 415                 DYN_DEBUG("\talloc_idx failed for %s", name);
 416                 IPFW_UH_WUNLOCK(ch);
 417                 free(obj, M_IPFW);
 418                 return (ENOSPC);
 419         }
 420         ipfw_objhash_add(ni, &obj->no);
 421         SRV_OBJECT(ch, obj->no.kidx) = obj;
 422         obj->no.refcnt++;
 423         *pkidx = obj->no.kidx;
 424         IPFW_UH_WUNLOCK(ch);
 425         DYN_DEBUG("\tcreated kidx %d", *pkidx);
 426         return (0);
 427 }
 428
 429 static void
 430 dyn_destroy(struct ip_fw_chain *ch, struct named_object *no)
 431 {
 432         struct dyn_state_obj *obj;
 433
 434         IPFW_UH_WLOCK_ASSERT(ch);
 435
 436         KASSERT(no->refcnt == 1,
 437             ("Destroying object '%s' (type %u, idx %u) with refcnt %u",
 438             no->name, no->etlv, no->kidx, no->refcnt));
 439
 440         DYN_DEBUG("kidx %d", no->kidx);
 441         obj = SRV_OBJECT(ch, no->kidx);
 442         SRV_OBJECT(ch, no->kidx) = NULL;
 443         ipfw_objhash_del(CHAIN_TO_SRV(ch), no);
 444         ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), no->kidx);
 445
 446         free(obj, M_IPFW);
 447 }
 448
 449 static struct opcode_obj_rewrite dyn_opcodes[] = {
 450         {
 451                 O_KEEP_STATE, IPFW_TLV_STATE_NAME,
 452                 dyn_classify, dyn_update,
 453                 dyn_findbyname, dyn_findbykidx,
 454                 dyn_create, dyn_destroy
 455         },
 456         {
 457                 O_CHECK_STATE, IPFW_TLV_STATE_NAME,
 458                 dyn_classify, dyn_update,
 459                 dyn_findbyname, dyn_findbykidx,
 460                 dyn_create, dyn_destroy
 461         },
 462         {
 463                 O_PROBE_STATE, IPFW_TLV_STATE_NAME,
 464                 dyn_classify, dyn_update,
 465                 dyn_findbyname, dyn_findbykidx,
 466                 dyn_create, dyn_destroy
 467         },
 468         {
 469                 O_LIMIT, IPFW_TLV_STATE_NAME,
 470                 dyn_classify, dyn_update,
 471                 dyn_findbyname, dyn_findbykidx,
 472                 dyn_create, dyn_destroy
 473         },
 474 };
 475 /**
 476  * Print customizable flow id description via log(9) facility.
 477  */
 478 static void
 479 print_dyn_rule_flags(const struct ipfw_flow_id *id, int dyn_type,
 480     int log_flags, char *prefix, char *postfix)
 481 {
 482         struct in_addr da;
 483 #ifdef INET6
 484         char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
 485 #else
 486         char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
 487 #endif
 488
 489 #ifdef INET6
 490         if (IS_IP6_FLOW_ID(id)) {
 491                 ip6_sprintf(src, &id->src_ip6);
 492                 ip6_sprintf(dst, &id->dst_ip6);
 493         } else
 494 #endif
 495         {
 496                 da.s_addr = htonl(id->src_ip);
 497                 inet_ntop(AF_INET, &da, src, sizeof(src));
 498                 da.s_addr = htonl(id->dst_ip);
 499                 inet_ntop(AF_INET, &da, dst, sizeof(dst));
 500         }
 501         log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
 502             prefix, dyn_type, src, id->src_port, dst,
 503             id->dst_port, DYN_COUNT, postfix);
 504 }
 505
 506 #define print_dyn_rule(id, dtype, prefix, postfix)      \
 507         print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
 508
 509 #define TIME_LEQ(a,b)       ((int)((a)-(b)) <= 0)
 510 #define TIME_LE(a,b)       ((int)((a)-(b)) < 0)
 511
 512 static void
 513 dyn_update_proto_state(ipfw_dyn_rule *q, const struct ipfw_flow_id *id,
 514     const void *ulp, int dir)
 515 {
 516         const struct tcphdr *tcp;
 517         uint32_t ack;
 518         u_char flags;
 519
 520         if (id->proto == IPPROTO_TCP) {
 521                 tcp = (const struct tcphdr *)ulp;
 522                 flags = id->_flags & (TH_FIN | TH_SYN | TH_RST);
 523 #define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
 524 #define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
 525 #define TCP_FLAGS       (TH_FLAGS | (TH_FLAGS << 8))
 526 #define ACK_FWD         0x10000                 /* fwd ack seen */
 527 #define ACK_REV         0x20000                 /* rev ack seen */
 528
 529                 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
 530                 switch (q->state & TCP_FLAGS) {
 531                 case TH_SYN:                    /* opening */
 532                         q->expire = time_uptime + V_dyn_syn_lifetime;
 533                         break;
 534
 535                 case BOTH_SYN:                  /* move to established */
 536                 case BOTH_SYN | TH_FIN:         /* one side tries to close */
 537                 case BOTH_SYN | (TH_FIN << 8):
 538 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
 539                         if (tcp == NULL)
 540                                 break;
 541
 542                         ack = ntohl(tcp->th_ack);
 543                         if (dir == MATCH_FORWARD) {
 544                                 if (q->ack_fwd == 0 ||
 545                                     _SEQ_GE(ack, q->ack_fwd)) {
 546                                         q->ack_fwd = ack;
 547                                         q->state |= ACK_FWD;
 548                                 }
 549                         } else {
 550                                 if (q->ack_rev == 0 ||
 551                                     _SEQ_GE(ack, q->ack_rev)) {
 552                                         q->ack_rev = ack;
 553                                         q->state |= ACK_REV;
 554                                 }
 555                         }
 556                         if ((q->state & (ACK_FWD | ACK_REV)) ==
 557                             (ACK_FWD | ACK_REV)) {
 558                                 q->expire = time_uptime + V_dyn_ack_lifetime;
 559                                 q->state &= ~(ACK_FWD | ACK_REV);
 560                         }
 561                         break;
 562
 563                 case BOTH_SYN | BOTH_FIN:       /* both sides closed */
 564                         if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
 565                                 V_dyn_fin_lifetime =
 566                                     V_dyn_keepalive_period - 1;
 567                         q->expire = time_uptime + V_dyn_fin_lifetime;
 568                         break;
 569
 570                 default:
 571 #if 0
 572                         /*
 573                          * reset or some invalid combination, but can also
 574                          * occur if we use keep-state the wrong way.
 575                          */
 576                         if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
 577                                 printf("invalid state: 0x%x\n", q->state);
 578 #endif
 579                         if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
 580                                 V_dyn_rst_lifetime =
 581                                     V_dyn_keepalive_period - 1;
 582                         q->expire = time_uptime + V_dyn_rst_lifetime;
 583                         break;
 584                 }
 585         } else if (id->proto == IPPROTO_UDP) {
 586                 q->expire = time_uptime + V_dyn_udp_lifetime;
 587         } else {
 588                 /* other protocols */
 589                 q->expire = time_uptime + V_dyn_short_lifetime;
 590         }
 591 }
 592
 593 /*
 594  * Lookup a dynamic rule, locked version.
 595  */
 596 static ipfw_dyn_rule *
 597 lookup_dyn_rule_locked(const struct ipfw_flow_id *pkt, const void *ulp,
 598     int i, int *match_direction, uint16_t kidx)
 599 {
 600         /*
 601          * Stateful ipfw extensions.
 602          * Lookup into dynamic session queue.
 603          */
 604         ipfw_dyn_rule *prev, *q = NULL;
 605         int dir;
 606
 607         IPFW_BUCK_ASSERT(i);
 608
 609         dir = MATCH_NONE;
 610         for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
 611                 if (q->dyn_type == O_LIMIT_PARENT)
 612                         continue;
 613
 614                 if (pkt->addr_type != q->id.addr_type)
 615                         continue;
 616
 617                 if (pkt->proto != q->id.proto)
 618                         continue;
 619
 620                 if (kidx != 0 && kidx != q->kidx)
 621                         continue;
 622
 623                 if (IS_IP6_FLOW_ID(pkt)) {
 624                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
 625                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
 626                             pkt->src_port == q->id.src_port &&
 627                             pkt->dst_port == q->id.dst_port) {
 628                                 dir = MATCH_FORWARD;
 629                                 break;
 630                         }
 631                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
 632                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
 633                             pkt->src_port == q->id.dst_port &&
 634                             pkt->dst_port == q->id.src_port) {
 635                                 dir = MATCH_REVERSE;
 636                                 break;
 637                         }
 638                 } else {
 639                         if (pkt->src_ip == q->id.src_ip &&
 640                             pkt->dst_ip == q->id.dst_ip &&
 641                             pkt->src_port == q->id.src_port &&
 642                             pkt->dst_port == q->id.dst_port) {
 643                                 dir = MATCH_FORWARD;
 644                                 break;
 645                         }
 646                         if (pkt->src_ip == q->id.dst_ip &&
 647                             pkt->dst_ip == q->id.src_ip &&
 648                             pkt->src_port == q->id.dst_port &&
 649                             pkt->dst_port == q->id.src_port) {
 650                                 dir = MATCH_REVERSE;
 651                                 break;
 652                         }
 653                 }
 654         }
 655         if (q == NULL)
 656                 goto done;      /* q = NULL, not found */
 657
 658         if (prev != NULL) {     /* found and not in front */
 659                 prev->next = q->next;
 660                 q->next = V_ipfw_dyn_v[i].head;
 661                 V_ipfw_dyn_v[i].head = q;
 662         }
 663
 664         /* update state according to flags */
 665         dyn_update_proto_state(q, pkt, ulp, dir);
 666 done:
 667         if (match_direction != NULL)
 668                 *match_direction = dir;
 669         return (q);
 670 }
 671
 672 struct ip_fw *
 673 ipfw_dyn_lookup_state(const struct ipfw_flow_id *pkt, const void *ulp,
 674     int pktlen, int *match_direction, uint16_t kidx)
 675 {
 676         struct ip_fw *rule;
 677         ipfw_dyn_rule *q;
 678         int i;
 679
 680         i = hash_packet(pkt, V_curr_dyn_buckets);
 681
 682         IPFW_BUCK_LOCK(i);
 683         q = lookup_dyn_rule_locked(pkt, ulp, i, match_direction, kidx);
 684         if (q == NULL)
 685                 rule = NULL;
 686         else {
 687                 rule = q->rule;
 688                 IPFW_INC_DYN_COUNTER(q, pktlen);
 689         }
 690         IPFW_BUCK_UNLOCK(i);
 691         return (rule);
 692 }
 693
 694 static int
 695 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
 696 {
 697         int i, k, nbuckets_old;
 698         ipfw_dyn_rule *q;
 699         struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
 700
 701         /* Check if given number is power of 2 and less than 64k */
 702         if ((nbuckets > 65536) || (!powerof2(nbuckets)))
 703                 return 1;
 704
 705         CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
 706             V_curr_dyn_buckets, nbuckets);
 707
 708         /* Allocate and initialize new hash */
 709         dyn_v = malloc(nbuckets * sizeof(*dyn_v), M_IPFW,
 710             M_WAITOK | M_ZERO);
 711
 712         for (i = 0 ; i < nbuckets; i++)
 713                 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
 714
 715         /*
 716          * Call upper half lock, as get_map() do to ease
 717          * read-only access to dynamic rules hash from sysctl
 718          */
 719         IPFW_UH_WLOCK(chain);
 720
 721         /*
 722          * Acquire chain write lock to permit hash access
 723          * for main traffic path without additional locks
 724          */
 725         IPFW_WLOCK(chain);
 726
 727         /* Save old values */
 728         nbuckets_old = V_curr_dyn_buckets;
 729         dyn_v_old = V_ipfw_dyn_v;
 730
 731         /* Skip relinking if array is not set up */
 732         if (V_ipfw_dyn_v == NULL)
 733                 V_curr_dyn_buckets = 0;
 734
 735         /* Re-link all dynamic states */
 736         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
 737                 while (V_ipfw_dyn_v[i].head != NULL) {
 738                         /* Remove from current chain */
 739                         q = V_ipfw_dyn_v[i].head;
 740                         V_ipfw_dyn_v[i].head = q->next;
 741
 742                         /* Get new hash value */
 743                         k = hash_packet(&q->id, nbuckets);
 744                         q->bucket = k;
 745                         /* Add to the new head */
 746                         q->next = dyn_v[k].head;
 747                         dyn_v[k].head = q;
 748              }
 749         }
 750
 751         /* Update current pointers/buckets values */
 752         V_curr_dyn_buckets = nbuckets;
 753         V_ipfw_dyn_v = dyn_v;
 754
 755         IPFW_WUNLOCK(chain);
 756
 757         IPFW_UH_WUNLOCK(chain);
 758
 759         /* Start periodic callout on initial creation */
 760         if (dyn_v_old == NULL) {
 761                 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
 762                 return (0);
 763         }
 764
 765         /* Destroy all mutexes */
 766         for (i = 0 ; i < nbuckets_old ; i++)
 767                 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
 768
 769         /* Free old hash */
 770         free(dyn_v_old, M_IPFW);
 771
 772         return 0;
 773 }
 774
 775 /**
 776  * Install state of type 'type' for a dynamic session.
 777  * The hash table contains two type of rules:
 778  * - regular rules (O_KEEP_STATE)
 779  * - rules for sessions with limited number of sess per user
 780  *   (O_LIMIT). When they are created, the parent is
 781  *   increased by 1, and decreased on delete. In this case,
 782  *   the third parameter is the parent rule and not the chain.
 783  * - "parent" rules for the above (O_LIMIT_PARENT).
 784  */
 785 static ipfw_dyn_rule *
 786 add_dyn_rule(const struct ipfw_flow_id *id, int i, uint8_t dyn_type,
 787     struct ip_fw *rule, uint16_t kidx)
 788 {
 789         ipfw_dyn_rule *r;
 790
 791         IPFW_BUCK_ASSERT(i);
 792
 793         r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
 794         if (r == NULL) {
 795                 if (last_log != time_uptime) {
 796                         last_log = time_uptime;
 797                         log(LOG_DEBUG,
 798                             "ipfw: Cannot allocate dynamic state, "
 799                             "consider increasing net.inet.ip.fw.dyn_max\n");
 800                 }
 801                 return NULL;
 802         }
 803         ipfw_dyn_count++;
 804
 805         /*
 806          * refcount on parent is already incremented, so
 807          * it is safe to use parent unlocked.
 808          */
 809         if (dyn_type == O_LIMIT) {
 810                 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
 811                 if ( parent->dyn_type != O_LIMIT_PARENT)
 812                         panic("invalid parent");
 813                 r->parent = parent;
 814                 rule = parent->rule;
 815         }
 816
 817         r->id = *id;
 818         r->expire = time_uptime + V_dyn_syn_lifetime;
 819         r->rule = rule;
 820         r->dyn_type = dyn_type;
 821         IPFW_ZERO_DYN_COUNTER(r);
 822         r->count = 0;
 823         r->kidx = kidx;
 824         r->bucket = i;
 825         r->next = V_ipfw_dyn_v[i].head;
 826         V_ipfw_dyn_v[i].head = r;
 827         DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
 828         return r;
 829 }
 830
 831 /**
 832  * lookup dynamic parent rule using pkt and rule as search keys.
 833  * If the lookup fails, then install one.
 834  */
 835 static ipfw_dyn_rule *
 836 lookup_dyn_parent(const struct ipfw_flow_id *pkt, int *pindex,
 837     struct ip_fw *rule, uint16_t kidx)
 838 {
 839         ipfw_dyn_rule *q;
 840         int i, is_v6;
 841
 842         is_v6 = IS_IP6_FLOW_ID(pkt);
 843         i = hash_packet( pkt, V_curr_dyn_buckets );
 844         *pindex = i;
 845         IPFW_BUCK_LOCK(i);
 846         for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
 847                 if (q->dyn_type == O_LIMIT_PARENT &&
 848                     kidx == q->kidx &&
 849                     rule == q->rule &&
 850                     pkt->proto == q->id.proto &&
 851                     pkt->src_port == q->id.src_port &&
 852                     pkt->dst_port == q->id.dst_port &&
 853                     (
 854                         (is_v6 &&
 855                          IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
 856                                 &(q->id.src_ip6)) &&
 857                          IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
 858                                 &(q->id.dst_ip6))) ||
 859                         (!is_v6 &&
 860                          pkt->src_ip == q->id.src_ip &&
 861                          pkt->dst_ip == q->id.dst_ip)
 862                     )
 863                 ) {
 864                         q->expire = time_uptime + V_dyn_short_lifetime;
 865                         DEB(print_dyn_rule(pkt, q->dyn_type,
 866                             "lookup_dyn_parent found", "");)
 867                         return q;
 868                 }
 869
 870         /* Add virtual limiting rule */
 871         return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule, kidx);
 872 }
 873
 874 /**
 875  * Install dynamic state for rule type cmd->o.opcode
 876  *
 877  * Returns 1 (failure) if state is not installed because of errors or because
 878  * session limitations are enforced.
 879  */
 880 int
 881 ipfw_dyn_install_state(struct ip_fw_chain *chain, struct ip_fw *rule,
 882     ipfw_insn_limit *cmd, struct ip_fw_args *args, uint32_t tablearg)
 883 {
 884         ipfw_dyn_rule *q;
 885         int i;
 886
 887         DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state",
 888             (cmd->o.arg1 == 0 ? "": DYN_STATE_OBJ(chain, &cmd->o)->name));)
 889
 890         i = hash_packet(&args->f_id, V_curr_dyn_buckets);
 891
 892         IPFW_BUCK_LOCK(i);
 893
 894         q = lookup_dyn_rule_locked(&args->f_id, NULL, i, NULL, cmd->o.arg1);
 895         if (q != NULL) {        /* should never occur */
 896                 DEB(
 897                 if (last_log != time_uptime) {
 898                         last_log = time_uptime;
 899                         printf("ipfw: %s: entry already present, done\n",
 900                             __func__);
 901                 })
 902                 IPFW_BUCK_UNLOCK(i);
 903                 return (0);
 904         }
 905
 906         /*
 907          * State limiting is done via uma(9) zone limiting.
 908          * Save pointer to newly-installed rule and reject
 909          * packet if add_dyn_rule() returned NULL.
 910          * Note q is currently set to NULL.
 911          */
 912
 913         switch (cmd->o.opcode) {
 914         case O_KEEP_STATE:      /* bidir rule */
 915                 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule,
 916                     cmd->o.arg1);
 917                 break;
 918
 919         case O_LIMIT: {         /* limit number of sessions */
 920                 struct ipfw_flow_id id;
 921                 ipfw_dyn_rule *parent;
 922                 uint32_t conn_limit;
 923                 uint16_t limit_mask = cmd->limit_mask;
 924                 int pindex;
 925
 926                 conn_limit = IP_FW_ARG_TABLEARG(chain, cmd->conn_limit, limit);
 927
 928                 DEB(
 929                 if (cmd->conn_limit == IP_FW_TARG)
 930                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
 931                             "(tablearg)\n", __func__, conn_limit);
 932                 else
 933                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
 934                             __func__, conn_limit);
 935                 )
 936
 937                 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
 938                 id.proto = args->f_id.proto;
 939                 id.addr_type = args->f_id.addr_type;
 940                 id.fib = M_GETFIB(args->m);
 941
 942                 if (IS_IP6_FLOW_ID (&(args->f_id))) {
 943                         bzero(&id.src_ip6, sizeof(id.src_ip6));
 944                         bzero(&id.dst_ip6, sizeof(id.dst_ip6));
 945
 946                         if (limit_mask & DYN_SRC_ADDR)
 947                                 id.src_ip6 = args->f_id.src_ip6;
 948                         if (limit_mask & DYN_DST_ADDR)
 949                                 id.dst_ip6 = args->f_id.dst_ip6;
 950                 } else {
 951                         if (limit_mask & DYN_SRC_ADDR)
 952                                 id.src_ip = args->f_id.src_ip;
 953                         if (limit_mask & DYN_DST_ADDR)
 954                                 id.dst_ip = args->f_id.dst_ip;
 955                 }
 956                 if (limit_mask & DYN_SRC_PORT)
 957                         id.src_port = args->f_id.src_port;
 958                 if (limit_mask & DYN_DST_PORT)
 959                         id.dst_port = args->f_id.dst_port;
 960
 961                 /*
 962                  * We have to release lock for previous bucket to
 963                  * avoid possible deadlock
 964                  */
 965                 IPFW_BUCK_UNLOCK(i);
 966
 967                 parent = lookup_dyn_parent(&id, &pindex, rule, cmd->o.arg1);
 968                 if (parent == NULL) {
 969                         printf("ipfw: %s: add parent failed\n", __func__);
 970                         IPFW_BUCK_UNLOCK(pindex);
 971                         return (1);
 972                 }
 973
 974                 if (parent->count >= conn_limit) {
 975                         if (V_fw_verbose && last_log != time_uptime) {
 976                                 char sbuf[24];
 977                                 last_log = time_uptime;
 978                                 snprintf(sbuf, sizeof(sbuf),
 979                                     "%d drop session",
 980                                     parent->rule->rulenum);
 981                                 print_dyn_rule_flags(&args->f_id,
 982                                     cmd->o.opcode,
 983                                     LOG_SECURITY | LOG_DEBUG,
 984                                     sbuf, "too many entries");
 985                         }
 986                         IPFW_BUCK_UNLOCK(pindex);
 987                         return (1);
 988                 }
 989                 /* Increment counter on parent */
 990                 parent->count++;
 991                 IPFW_BUCK_UNLOCK(pindex);
 992
 993                 IPFW_BUCK_LOCK(i);
 994                 q = add_dyn_rule(&args->f_id, i, O_LIMIT,
 995                     (struct ip_fw *)parent, cmd->o.arg1);
 996                 if (q == NULL) {
 997                         /* Decrement index and notify caller */
 998                         IPFW_BUCK_UNLOCK(i);
 999                         IPFW_BUCK_LOCK(pindex);
1000                         parent->count--;
1001                         IPFW_BUCK_UNLOCK(pindex);
1002                         return (1);
1003                 }
1004                 break;
1005         }
1006         default:
1007                 printf("ipfw: %s: unknown dynamic rule type %u\n",
1008                     __func__, cmd->o.opcode);
1009         }
1010
1011         if (q == NULL) {
1012                 IPFW_BUCK_UNLOCK(i);
1013                 return (1);     /* Notify caller about failure */
1014         }
1015
1016         dyn_update_proto_state(q, &args->f_id, NULL, MATCH_FORWARD);
1017         IPFW_BUCK_UNLOCK(i);
1018         return (0);
1019 }
1020
1021 /*
1022  * Queue keepalive packets for given dynamic rule
1023  */
1024 static struct mbuf **
1025 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
1026 {
1027         struct mbuf *m_rev, *m_fwd;
1028
1029         m_rev = (q->state & ACK_REV) ? NULL :
1030             ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
1031         m_fwd = (q->state & ACK_FWD) ? NULL :
1032             ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
1033
1034         if (m_rev != NULL) {
1035                 *mtailp = m_rev;
1036                 mtailp = &(*mtailp)->m_nextpkt;
1037         }
1038         if (m_fwd != NULL) {
1039                 *mtailp = m_fwd;
1040                 mtailp = &(*mtailp)->m_nextpkt;
1041         }
1042
1043         return (mtailp);
1044 }
1045
1046 /*
1047  * This procedure is used to perform various maintenance
1048  * on dynamic hash list. Currently it is called every second.
1049  */
1050 static void
1051 ipfw_dyn_tick(void * vnetx)
1052 {
1053         struct ip_fw_chain *chain;
1054         int check_ka = 0;
1055 #ifdef VIMAGE
1056         struct vnet *vp = vnetx;
1057 #endif
1058
1059         CURVNET_SET(vp);
1060
1061         chain = &V_layer3_chain;
1062
1063         /* Run keepalive checks every keepalive_period iff ka is enabled */
1064         if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
1065             (V_dyn_keepalive != 0)) {
1066                 V_dyn_keepalive_last = time_uptime;
1067                 check_ka = 1;
1068         }
1069
1070         check_dyn_rules(chain, NULL, check_ka, 1);
1071
1072         callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
1073
1074         CURVNET_RESTORE();
1075 }
1076
1077
1078 /*
1079  * Walk through all dynamic states doing generic maintenance:
1080  * 1) free expired states
1081  * 2) free all states based on deleted rule / set
1082  * 3) send keepalives for states if needed
1083  *
1084  * @chain - pointer to current ipfw rules chain
1085  * @rule - delete all states originated by given rule if != NULL
1086  * @set - delete all states originated by any rule in set @set if != RESVD_SET
1087  * @check_ka - perform checking/sending keepalives
1088  * @timer - indicate call from timer routine.
1089  *
1090  * Timer routine must call this function unlocked to permit
1091  * sending keepalives/resizing table.
1092  *
1093  * Others has to call function with IPFW_UH_WLOCK held.
1094  * Additionally, function assume that dynamic rule/set is
1095  * ALREADY deleted so no new states can be generated by
1096  * 'deleted' rules.
1097  *
1098  * Write lock is needed to ensure that unused parent rules
1099  * are not freed by other instance (see stage 2, 3)
1100  */
1101 static void
1102 check_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt,
1103     int check_ka, int timer)
1104 {
1105         struct mbuf *m0, *m, *mnext, **mtailp;
1106         struct ip *h;
1107         int i, dyn_count, new_buckets = 0, max_buckets;
1108         int expired = 0, expired_limits = 0, parents = 0, total = 0;
1109         ipfw_dyn_rule *q, *q_prev, *q_next;
1110         ipfw_dyn_rule *exp_head, **exptailp;
1111         ipfw_dyn_rule *exp_lhead, **expltailp;
1112
1113         KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1114             __func__));
1115
1116         /* Avoid possible LOR */
1117         KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1118             __func__));
1119
1120         /*
1121          * Do not perform any checks if we currently have no dynamic states
1122          */
1123         if (DYN_COUNT == 0)
1124                 return;
1125
1126         /* Expired states */
1127         exp_head = NULL;
1128         exptailp = &exp_head;
1129
1130         /* Expired limit states */
1131         exp_lhead = NULL;
1132         expltailp = &exp_lhead;
1133
1134         /*
1135          * We make a chain of packets to go out here -- not deferring
1136          * until after we drop the IPFW dynamic rule lock would result
1137          * in a lock order reversal with the normal packet input -> ipfw
1138          * call stack.
1139          */
1140         m0 = NULL;
1141         mtailp = &m0;
1142
1143         /* Protect from hash resizing */
1144         if (timer != 0)
1145                 IPFW_UH_WLOCK(chain);
1146         else
1147                 IPFW_UH_WLOCK_ASSERT(chain);
1148
1149 #define NEXT_RULE()     { q_prev = q; q = q->next ; continue; }
1150
1151         /* Stage 1: perform requested deletion */
1152         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1153                 IPFW_BUCK_LOCK(i);
1154                 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1155                         /* account every rule */
1156                         total++;
1157
1158                         /* Skip parent rules at all */
1159                         if (q->dyn_type == O_LIMIT_PARENT) {
1160                                 parents++;
1161                                 NEXT_RULE();
1162                         }
1163
1164                         /*
1165                          * Remove rules which are:
1166                          * 1) expired
1167                          * 2) matches deletion range
1168                          */
1169                         if ((TIME_LEQ(q->expire, time_uptime)) ||
1170                             (rt != NULL && ipfw_match_range(q->rule, rt))) {
1171                                 if (TIME_LE(time_uptime, q->expire) &&
1172                                     q->dyn_type == O_KEEP_STATE &&
1173                                     V_dyn_keep_states != 0) {
1174                                         /*
1175                                          * Do not delete state if
1176                                          * it is not expired and
1177                                          * dyn_keep_states is ON.
1178                                          * However we need to re-link it
1179                                          * to any other stable rule
1180                                          */
1181                                         q->rule = chain->default_rule;
1182                                         NEXT_RULE();
1183                                 }
1184
1185                                 /* Unlink q from current list */
1186                                 q_next = q->next;
1187                                 if (q == V_ipfw_dyn_v[i].head)
1188                                         V_ipfw_dyn_v[i].head = q_next;
1189                                 else
1190                                         q_prev->next = q_next;
1191
1192                                 q->next = NULL;
1193
1194                                 /* queue q to expire list */
1195                                 if (q->dyn_type != O_LIMIT) {
1196                                         *exptailp = q;
1197                                         exptailp = &(*exptailp)->next;
1198                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1199                                             "unlink entry", "left");
1200                                         )
1201                                 } else {
1202                                         /* Separate list for limit rules */
1203                                         *expltailp = q;
1204                                         expltailp = &(*expltailp)->next;
1205                                         expired_limits++;
1206                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1207                                             "unlink limit entry", "left");
1208                                         )
1209                                 }
1210
1211                                 q = q_next;
1212                                 expired++;
1213                                 continue;
1214                         }
1215
1216                         /*
1217                          * Check if we need to send keepalive:
1218                          * we need to ensure if is time to do KA,
1219                          * this is established TCP session, and
1220                          * expire time is within keepalive interval
1221                          */
1222                         if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1223                             ((q->state & BOTH_SYN) == BOTH_SYN) &&
1224                             (TIME_LEQ(q->expire, time_uptime +
1225                               V_dyn_keepalive_interval)))
1226                                 mtailp = ipfw_dyn_send_ka(mtailp, q);
1227
1228                         NEXT_RULE();
1229                 }
1230                 IPFW_BUCK_UNLOCK(i);
1231         }
1232
1233         /* Stage 2: decrement counters from O_LIMIT parents */
1234         if (expired_limits != 0) {
1235                 /*
1236                  * XXX: Note that deleting set with more than one
1237                  * heavily-used LIMIT rules can result in overwhelming
1238                  * locking due to lack of per-hash value sorting
1239                  *
1240                  * We should probably think about:
1241                  * 1) pre-allocating hash of size, say,
1242                  * MAX(16, V_curr_dyn_buckets / 1024)
1243                  * 2) checking if expired_limits is large enough
1244                  * 3) If yes, init hash (or its part), re-link
1245                  * current list and start decrementing procedure in
1246                  * each bucket separately
1247                  */
1248
1249                 /*
1250                  * Small optimization: do not unlock bucket until
1251                  * we see the next item resides in different bucket
1252                  */
1253                 if (exp_lhead != NULL) {
1254                         i = exp_lhead->parent->bucket;
1255                         IPFW_BUCK_LOCK(i);
1256                 }
1257                 for (q = exp_lhead; q != NULL; q = q->next) {
1258                         if (i != q->parent->bucket) {
1259                                 IPFW_BUCK_UNLOCK(i);
1260                                 i = q->parent->bucket;
1261                                 IPFW_BUCK_LOCK(i);
1262                         }
1263
1264                         /* Decrease parent refcount */
1265                         q->parent->count--;
1266                 }
1267                 if (exp_lhead != NULL)
1268                         IPFW_BUCK_UNLOCK(i);
1269         }
1270
1271         /*
1272          * We protectet ourselves from unused parent deletion
1273          * (from the timer function) by holding UH write lock.
1274          */
1275
1276         /* Stage 3: remove unused parent rules */
1277         if ((parents != 0) && (expired != 0)) {
1278                 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1279                         IPFW_BUCK_LOCK(i);
1280                         for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1281                                 if (q->dyn_type != O_LIMIT_PARENT)
1282                                         NEXT_RULE();
1283
1284                                 if (q->count != 0)
1285                                         NEXT_RULE();
1286
1287                                 /* Parent rule without consumers */
1288
1289                                 /* Unlink q from current list */
1290                                 q_next = q->next;
1291                                 if (q == V_ipfw_dyn_v[i].head)
1292                                         V_ipfw_dyn_v[i].head = q_next;
1293                                 else
1294                                         q_prev->next = q_next;
1295
1296                                 q->next = NULL;
1297
1298                                 /* Add to expired list */
1299                                 *exptailp = q;
1300                                 exptailp = &(*exptailp)->next;
1301
1302                                 DEB(print_dyn_rule(&q->id, q->dyn_type,
1303                                     "unlink parent entry", "left");
1304                                 )
1305
1306                                 expired++;
1307
1308                                 q = q_next;
1309                         }
1310                         IPFW_BUCK_UNLOCK(i);
1311                 }
1312         }
1313
1314 #undef NEXT_RULE
1315
1316         if (timer != 0) {
1317                 /*
1318                  * Check if we need to resize hash:
1319                  * if current number of states exceeds number of buckes in hash,
1320                  * grow hash size to the minimum power of 2 which is bigger than
1321                  * current states count. Limit hash size by 64k.
1322                  */
1323                 max_buckets = (V_dyn_buckets_max > 65536) ?
1324                     65536 : V_dyn_buckets_max;
1325
1326                 dyn_count = DYN_COUNT;
1327
1328                 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1329                     (dyn_count < max_buckets)) {
1330                         new_buckets = V_curr_dyn_buckets;
1331                         while (new_buckets < dyn_count) {
1332                                 new_buckets *= 2;
1333
1334                                 if (new_buckets >= max_buckets)
1335                                         break;
1336                         }
1337                 }
1338
1339                 IPFW_UH_WUNLOCK(chain);
1340         }
1341
1342         /* Finally delete old states ad limits if any */
1343         for (q = exp_head; q != NULL; q = q_next) {
1344                 q_next = q->next;
1345                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1346                 ipfw_dyn_count--;
1347         }
1348
1349         for (q = exp_lhead; q != NULL; q = q_next) {
1350                 q_next = q->next;
1351                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1352                 ipfw_dyn_count--;
1353         }
1354
1355         /*
1356          * The rest code MUST be called from timer routine only
1357          * without holding any locks
1358          */
1359         if (timer == 0)
1360                 return;
1361
1362         /* Send keepalive packets if any */
1363         for (m = m0; m != NULL; m = mnext) {
1364                 mnext = m->m_nextpkt;
1365                 m->m_nextpkt = NULL;
1366                 h = mtod(m, struct ip *);
1367                 if (h->ip_v == 4)
1368                         ip_output(m, NULL, NULL, 0, NULL, NULL);
1369 #ifdef INET6
1370                 else
1371                         ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1372 #endif
1373         }
1374
1375         /* Run table resize without holding any locks */
1376         if (new_buckets != 0)
1377                 resize_dynamic_table(chain, new_buckets);
1378 }
1379
1380 /*
1381  * Deletes all dynamic rules originated by given rule or all rules in
1382  * given set. Specify RESVD_SET to indicate set should not be used.
1383  * @chain - pointer to current ipfw rules chain
1384  * @rr - delete all states originated by rules in matched range.
1385  *
1386  * Function has to be called with IPFW_UH_WLOCK held.
1387  * Additionally, function assume that dynamic rule/set is
1388  * ALREADY deleted so no new states can be generated by
1389  * 'deleted' rules.
1390  */
1391 void
1392 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt)
1393 {
1394
1395         check_dyn_rules(chain, rt, 0, 0);
1396 }
1397
1398 /*
1399  * Check if rule contains at least one dynamic opcode.
1400  *
1401  * Returns 1 if such opcode is found, 0 otherwise.
1402  */
1403 int
1404 ipfw_is_dyn_rule(struct ip_fw *rule)
1405 {
1406         int cmdlen, l;
1407         ipfw_insn *cmd;
1408
1409         l = rule->cmd_len;
1410         cmd = rule->cmd;
1411         cmdlen = 0;
1412         for ( ; l > 0 ; l -= cmdlen, cmd += cmdlen) {
1413                 cmdlen = F_LEN(cmd);
1414
1415                 switch (cmd->opcode) {
1416                 case O_LIMIT:
1417                 case O_KEEP_STATE:
1418                 case O_PROBE_STATE:
1419                 case O_CHECK_STATE:
1420                         return (1);
1421                 }
1422         }
1423
1424         return (0);
1425 }
1426
1427 void
1428 ipfw_dyn_init(struct ip_fw_chain *chain)
1429 {
1430
1431         V_ipfw_dyn_v = NULL;
1432         V_dyn_buckets_max = 256; /* must be power of 2 */
1433         V_curr_dyn_buckets = 256; /* must be power of 2 */
1434
1435         V_dyn_ack_lifetime = 300;
1436         V_dyn_syn_lifetime = 20;
1437         V_dyn_fin_lifetime = 1;
1438         V_dyn_rst_lifetime = 1;
1439         V_dyn_udp_lifetime = 10;
1440         V_dyn_short_lifetime = 5;
1441
1442         V_dyn_keepalive_interval = 20;
1443         V_dyn_keepalive_period = 5;
1444         V_dyn_keepalive = 1;    /* do send keepalives */
1445         V_dyn_keepalive_last = time_uptime;
1446
1447         V_dyn_max = 16384; /* max # of dynamic rules */
1448
1449         V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1450             sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1451             UMA_ALIGN_PTR, 0);
1452
1453         /* Enforce limit on dynamic rules */
1454         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1455
1456         callout_init(&V_ipfw_timeout, 1);
1457
1458         /*
1459          * This can potentially be done on first dynamic rule
1460          * being added to chain.
1461          */
1462         resize_dynamic_table(chain, V_curr_dyn_buckets);
1463         IPFW_ADD_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes);
1464 }
1465
1466 void
1467 ipfw_dyn_uninit(int pass)
1468 {
1469         int i;
1470
1471         if (pass == 0) {
1472                 callout_drain(&V_ipfw_timeout);
1473                 return;
1474         }
1475         IPFW_DEL_OBJ_REWRITER(IS_DEFAULT_VNET(curvnet), dyn_opcodes);
1476
1477         if (V_ipfw_dyn_v != NULL) {
1478                 /*
1479                  * Skip deleting all dynamic states -
1480                  * uma_zdestroy() does this more efficiently;
1481                  */
1482
1483                 /* Destroy all mutexes */
1484                 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1485                         IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1486                 free(V_ipfw_dyn_v, M_IPFW);
1487                 V_ipfw_dyn_v = NULL;
1488         }
1489
1490         uma_zdestroy(V_ipfw_dyn_rule_zone);
1491 }
1492
1493 #ifdef SYSCTL_NODE
1494 /*
1495  * Get/set maximum number of dynamic states in given VNET instance.
1496  */
1497 static int
1498 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1499 {
1500         int error;
1501         unsigned int nstates;
1502
1503         nstates = V_dyn_max;
1504
1505         error = sysctl_handle_int(oidp, &nstates, 0, req);
1506         /* Read operation or some error */
1507         if ((error != 0) || (req->newptr == NULL))
1508                 return (error);
1509
1510         V_dyn_max = nstates;
1511         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1512
1513         return (0);
1514 }
1515
1516 /*
1517  * Get current number of dynamic states in given VNET instance.
1518  */
1519 static int
1520 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1521 {
1522         int error;
1523         unsigned int nstates;
1524
1525         nstates = DYN_COUNT;
1526
1527         error = sysctl_handle_int(oidp, &nstates, 0, req);
1528
1529         return (error);
1530 }
1531 #endif
1532
1533 /*
1534  * Returns size of dynamic states in legacy format
1535  */
1536 int
1537 ipfw_dyn_len(void)
1538 {
1539
1540         return (V_ipfw_dyn_v == NULL) ? 0 :
1541                 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1542 }
1543
1544 /*
1545  * Returns number of dynamic states.
1546  * Used by dump format v1 (current).
1547  */
1548 int
1549 ipfw_dyn_get_count(void)
1550 {
1551
1552         return (V_ipfw_dyn_v == NULL) ? 0 : DYN_COUNT;
1553 }
1554
1555 static void
1556 export_dyn_rule(ipfw_dyn_rule *src, ipfw_dyn_rule *dst)
1557 {
1558         uint16_t rulenum;
1559
1560         rulenum = (uint16_t)src->rule->rulenum;
1561         memcpy(dst, src, sizeof(*src));
1562         memcpy(&dst->rule, &rulenum, sizeof(rulenum));
1563         /*
1564          * store set number into high word of
1565          * dst->rule pointer.
1566          */
1567         memcpy((char *)&dst->rule + sizeof(rulenum), &src->rule->set,
1568             sizeof(src->rule->set));
1569         /*
1570          * store a non-null value in "next".
1571          * The userland code will interpret a
1572          * NULL here as a marker
1573          * for the last dynamic rule.
1574          */
1575         memcpy(&dst->next, &dst, sizeof(dst));
1576         dst->expire = TIME_LEQ(dst->expire, time_uptime) ?  0:
1577             dst->expire - time_uptime;
1578 }
1579
1580 /*
1581  * Fills int buffer given by @sd with dynamic states.
1582  * Used by dump format v1 (current).
1583  *
1584  * Returns 0 on success.
1585  */
1586 int
1587 ipfw_dump_states(struct ip_fw_chain *chain, struct sockopt_data *sd)
1588 {
1589         ipfw_dyn_rule *p;
1590         ipfw_obj_dyntlv *dst, *last;
1591         ipfw_obj_ctlv *ctlv;
1592         int i;
1593         size_t sz;
1594
1595         if (V_ipfw_dyn_v == NULL)
1596                 return (0);
1597
1598         IPFW_UH_RLOCK_ASSERT(chain);
1599
1600         ctlv = (ipfw_obj_ctlv *)ipfw_get_sopt_space(sd, sizeof(*ctlv));
1601         if (ctlv == NULL)
1602                 return (ENOMEM);
1603         sz = sizeof(ipfw_obj_dyntlv);
1604         ctlv->head.type = IPFW_TLV_DYNSTATE_LIST;
1605         ctlv->objsize = sz;
1606         last = NULL;
1607
1608         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1609                 IPFW_BUCK_LOCK(i);
1610                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1611                         dst = (ipfw_obj_dyntlv *)ipfw_get_sopt_space(sd, sz);
1612                         if (dst == NULL) {
1613                                 IPFW_BUCK_UNLOCK(i);
1614                                 return (ENOMEM);
1615                         }
1616
1617                         export_dyn_rule(p, &dst->state);
1618                         dst->head.length = sz;
1619                         dst->head.type = IPFW_TLV_DYN_ENT;
1620                         last = dst;
1621                 }
1622                 IPFW_BUCK_UNLOCK(i);
1623         }
1624
1625         if (last != NULL) /* mark last dynamic rule */
1626                 last->head.flags = IPFW_DF_LAST;
1627
1628         return (0);
1629 }
1630
1631 /*
1632  * Fill given buffer with dynamic states (legacy format).
1633  * IPFW_UH_RLOCK has to be held while calling.
1634  */
1635 void
1636 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1637 {
1638         ipfw_dyn_rule *p, *last = NULL;
1639         char *bp;
1640         int i;
1641
1642         if (V_ipfw_dyn_v == NULL)
1643                 return;
1644         bp = *pbp;
1645
1646         IPFW_UH_RLOCK_ASSERT(chain);
1647
1648         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1649                 IPFW_BUCK_LOCK(i);
1650                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1651                         if (bp + sizeof *p <= ep) {
1652                                 ipfw_dyn_rule *dst =
1653                                         (ipfw_dyn_rule *)bp;
1654
1655                                 export_dyn_rule(p, dst);
1656                                 last = dst;
1657                                 bp += sizeof(ipfw_dyn_rule);
1658                         }
1659                 }
1660                 IPFW_BUCK_UNLOCK(i);
1661         }
1662
1663         if (last != NULL) /* mark last dynamic rule */
1664                 bzero(&last->next, sizeof(last));
1665         *pbp = bp;
1666 }
1667 /* end of file */