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/vnet.h>
  58
  59 #include <netinet/in.h>
  60 #include <netinet/ip.h>
  61 #include <netinet/ip_var.h>     /* ip_defttl */
  62 #include <netinet/ip_fw.h>
  63 #include <netinet/tcp_var.h>
  64 #include <netinet/udp.h>
  65
  66 #include <netinet/ip6.h>        /* IN6_ARE_ADDR_EQUAL */
  67 #ifdef INET6
  68 #include <netinet6/in6_var.h>
  69 #include <netinet6/ip6_var.h>
  70 #endif
  71
  72 #include <netpfil/ipfw/ip_fw_private.h>
  73
  74 #include <machine/in_cksum.h>   /* XXX for in_cksum */
  75
  76 #ifdef MAC
  77 #include <security/mac/mac_framework.h>
  78 #endif
  79
  80 /*
  81  * Description of dynamic rules.
  82  *
  83  * Dynamic rules are stored in lists accessed through a hash table
  84  * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
  85  * be modified through the sysctl variable dyn_buckets which is
  86  * updated when the table becomes empty.
  87  *
  88  * XXX currently there is only one list, ipfw_dyn.
  89  *
  90  * When a packet is received, its address fields are first masked
  91  * with the mask defined for the rule, then hashed, then matched
  92  * against the entries in the corresponding list.
  93  * Dynamic rules can be used for different purposes:
  94  *  + stateful rules;
  95  *  + enforcing limits on the number of sessions;
  96  *  + in-kernel NAT (not implemented yet)
  97  *
  98  * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
  99  * measured in seconds and depending on the flags.
 100  *
 101  * The total number of dynamic rules is equal to UMA zone items count.
 102  * The max number of dynamic rules is dyn_max. When we reach
 103  * the maximum number of rules we do not create anymore. This is
 104  * done to avoid consuming too much memory, but also too much
 105  * time when searching on each packet (ideally, we should try instead
 106  * to put a limit on the length of the list on each bucket...).
 107  *
 108  * Each dynamic rule holds a pointer to the parent ipfw rule so
 109  * we know what action to perform. Dynamic rules are removed when
 110  * the parent rule is deleted. This can be changed by dyn_keep_states
 111  * sysctl.
 112  *
 113  * There are some limitations with dynamic rules -- we do not
 114  * obey the 'randomized match', and we do not do multiple
 115  * passes through the firewall. XXX check the latter!!!
 116  */
 117
 118 struct ipfw_dyn_bucket {
 119         struct mtx      mtx;            /* Bucket protecting lock */
 120         ipfw_dyn_rule   *head;          /* Pointer to first rule */
 121 };
 122
 123 /*
 124  * Static variables followed by global ones
 125  */
 126 static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v);
 127 static VNET_DEFINE(u_int32_t, dyn_buckets_max);
 128 static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
 129 static VNET_DEFINE(struct callout, ipfw_timeout);
 130 #define V_ipfw_dyn_v                    VNET(ipfw_dyn_v)
 131 #define V_dyn_buckets_max               VNET(dyn_buckets_max)
 132 #define V_curr_dyn_buckets              VNET(curr_dyn_buckets)
 133 #define V_ipfw_timeout                  VNET(ipfw_timeout)
 134
 135 static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone);
 136 #define V_ipfw_dyn_rule_zone            VNET(ipfw_dyn_rule_zone)
 137
 138 #define IPFW_BUCK_LOCK_INIT(b)  \
 139         mtx_init(&(b)->mtx, "IPFW dynamic bucket", NULL, MTX_DEF)
 140 #define IPFW_BUCK_LOCK_DESTROY(b)       \
 141         mtx_destroy(&(b)->mtx)
 142 #define IPFW_BUCK_LOCK(i)       mtx_lock(&V_ipfw_dyn_v[(i)].mtx)
 143 #define IPFW_BUCK_UNLOCK(i)     mtx_unlock(&V_ipfw_dyn_v[(i)].mtx)
 144 #define IPFW_BUCK_ASSERT(i)     mtx_assert(&V_ipfw_dyn_v[(i)].mtx, MA_OWNED)
 145
 146
 147 static VNET_DEFINE(int, dyn_keep_states);
 148 #define V_dyn_keep_states               VNET(dyn_keep_states)
 149
 150 /*
 151  * Timeouts for various events in handing dynamic rules.
 152  */
 153 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
 154 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
 155 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
 156 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
 157 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
 158 static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
 159
 160 #define V_dyn_ack_lifetime              VNET(dyn_ack_lifetime)
 161 #define V_dyn_syn_lifetime              VNET(dyn_syn_lifetime)
 162 #define V_dyn_fin_lifetime              VNET(dyn_fin_lifetime)
 163 #define V_dyn_rst_lifetime              VNET(dyn_rst_lifetime)
 164 #define V_dyn_udp_lifetime              VNET(dyn_udp_lifetime)
 165 #define V_dyn_short_lifetime            VNET(dyn_short_lifetime)
 166
 167 /*
 168  * Keepalives are sent if dyn_keepalive is set. They are sent every
 169  * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
 170  * seconds of lifetime of a rule.
 171  * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
 172  * than dyn_keepalive_period.
 173  */
 174
 175 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
 176 static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
 177 static VNET_DEFINE(u_int32_t, dyn_keepalive);
 178 static VNET_DEFINE(time_t, dyn_keepalive_last);
 179
 180 #define V_dyn_keepalive_interval        VNET(dyn_keepalive_interval)
 181 #define V_dyn_keepalive_period          VNET(dyn_keepalive_period)
 182 #define V_dyn_keepalive                 VNET(dyn_keepalive)
 183 #define V_dyn_keepalive_last            VNET(dyn_keepalive_last)
 184
 185 static VNET_DEFINE(u_int32_t, dyn_max);         /* max # of dynamic rules */
 186
 187 #define DYN_COUNT                       uma_zone_get_cur(V_ipfw_dyn_rule_zone)
 188 #define V_dyn_max                       VNET(dyn_max)
 189
 190 /* for userspace, we emulate the uma_zone_counter with ipfw_dyn_count */
 191 static int ipfw_dyn_count;      /* number of objects */
 192
 193 #ifdef USERSPACE /* emulation of UMA object counters for userspace */
 194 #define uma_zone_get_cur(x)     ipfw_dyn_count
 195 #endif /* USERSPACE */
 196
 197 static int last_log;    /* Log ratelimiting */
 198
 199 static void ipfw_dyn_tick(void *vnetx);
 200 static void check_dyn_rules(struct ip_fw_chain *, ipfw_range_tlv *, int, int);
 201 #ifdef SYSCTL_NODE
 202
 203 static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS);
 204 static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS);
 205
 206 SYSBEGIN(f2)
 207
 208 SYSCTL_DECL(_net_inet_ip_fw);
 209 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
 210     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_buckets_max), 0,
 211     "Max number of dyn. buckets");
 212 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets,
 213     CTLFLAG_VNET | CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0,
 214     "Current Number of dyn. buckets");
 215 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, dyn_count,
 216     CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RD, 0, 0, sysctl_ipfw_dyn_count, "IU",
 217     "Number of dyn. rules");
 218 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, dyn_max,
 219     CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, 0, 0, sysctl_ipfw_dyn_max, "IU",
 220     "Max number of dyn. rules");
 221 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime,
 222     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0,
 223     "Lifetime of dyn. rules for acks");
 224 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime,
 225     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0,
 226     "Lifetime of dyn. rules for syn");
 227 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime,
 228     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0,
 229     "Lifetime of dyn. rules for fin");
 230 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime,
 231     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0,
 232     "Lifetime of dyn. rules for rst");
 233 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime,
 234     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0,
 235     "Lifetime of dyn. rules for UDP");
 236 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime,
 237     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0,
 238     "Lifetime of dyn. rules for other situations");
 239 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
 240     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
 241     "Enable keepalives for dyn. rules");
 242 SYSCTL_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keep_states,
 243     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(dyn_keep_states), 0,
 244     "Do not flush dynamic states on rule deletion");
 245
 246 SYSEND
 247
 248 #endif /* SYSCTL_NODE */
 249
 250
 251 #ifdef INET6
 252 static __inline int
 253 hash_packet6(struct ipfw_flow_id *id)
 254 {
 255         u_int32_t i;
 256         i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
 257             (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
 258             (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
 259             (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
 260             (id->dst_port) ^ (id->src_port);
 261         return 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) ^ (id->dst_port) ^ (id->src_port);
 281         i &= (buckets - 1);
 282         return i;
 283 }
 284
 285 /**
 286  * Print customizable flow id description via log(9) facility.
 287  */
 288 static void
 289 print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
 290     char *prefix, char *postfix)
 291 {
 292         struct in_addr da;
 293 #ifdef INET6
 294         char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
 295 #else
 296         char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
 297 #endif
 298
 299 #ifdef INET6
 300         if (IS_IP6_FLOW_ID(id)) {
 301                 ip6_sprintf(src, &id->src_ip6);
 302                 ip6_sprintf(dst, &id->dst_ip6);
 303         } else
 304 #endif
 305         {
 306                 da.s_addr = htonl(id->src_ip);
 307                 inet_ntop(AF_INET, &da, src, sizeof(src));
 308                 da.s_addr = htonl(id->dst_ip);
 309                 inet_ntop(AF_INET, &da, dst, sizeof(dst));
 310         }
 311         log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
 312             prefix, dyn_type, src, id->src_port, dst,
 313             id->dst_port, DYN_COUNT, postfix);
 314 }
 315
 316 #define print_dyn_rule(id, dtype, prefix, postfix)      \
 317         print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
 318
 319 #define TIME_LEQ(a,b)       ((int)((a)-(b)) <= 0)
 320 #define TIME_LE(a,b)       ((int)((a)-(b)) < 0)
 321
 322 /*
 323  * Lookup a dynamic rule, locked version.
 324  */
 325 static ipfw_dyn_rule *
 326 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
 327     struct tcphdr *tcp)
 328 {
 329         /*
 330          * Stateful ipfw extensions.
 331          * Lookup into dynamic session queue.
 332          */
 333 #define MATCH_REVERSE   0
 334 #define MATCH_FORWARD   1
 335 #define MATCH_NONE      2
 336 #define MATCH_UNKNOWN   3
 337         int dir = MATCH_NONE;
 338         ipfw_dyn_rule *prev, *q = NULL;
 339
 340         IPFW_BUCK_ASSERT(i);
 341
 342         for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
 343                 if (q->dyn_type == O_LIMIT_PARENT && q->count)
 344                         continue;
 345
 346                 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
 347                         continue;
 348
 349                 if (IS_IP6_FLOW_ID(pkt)) {
 350                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
 351                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
 352                             pkt->src_port == q->id.src_port &&
 353                             pkt->dst_port == q->id.dst_port) {
 354                                 dir = MATCH_FORWARD;
 355                                 break;
 356                         }
 357                         if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
 358                             IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
 359                             pkt->src_port == q->id.dst_port &&
 360                             pkt->dst_port == q->id.src_port) {
 361                                 dir = MATCH_REVERSE;
 362                                 break;
 363                         }
 364                 } else {
 365                         if (pkt->src_ip == q->id.src_ip &&
 366                             pkt->dst_ip == q->id.dst_ip &&
 367                             pkt->src_port == q->id.src_port &&
 368                             pkt->dst_port == q->id.dst_port) {
 369                                 dir = MATCH_FORWARD;
 370                                 break;
 371                         }
 372                         if (pkt->src_ip == q->id.dst_ip &&
 373                             pkt->dst_ip == q->id.src_ip &&
 374                             pkt->src_port == q->id.dst_port &&
 375                             pkt->dst_port == q->id.src_port) {
 376                                 dir = MATCH_REVERSE;
 377                                 break;
 378                         }
 379                 }
 380         }
 381         if (q == NULL)
 382                 goto done;      /* q = NULL, not found */
 383
 384         if (prev != NULL) {     /* found and not in front */
 385                 prev->next = q->next;
 386                 q->next = V_ipfw_dyn_v[i].head;
 387                 V_ipfw_dyn_v[i].head = q;
 388         }
 389         if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
 390                 uint32_t ack;
 391                 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
 392
 393 #define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
 394 #define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
 395 #define TCP_FLAGS       (TH_FLAGS | (TH_FLAGS << 8))
 396 #define ACK_FWD         0x10000                 /* fwd ack seen */
 397 #define ACK_REV         0x20000                 /* rev ack seen */
 398
 399                 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
 400                 switch (q->state & TCP_FLAGS) {
 401                 case TH_SYN:                    /* opening */
 402                         q->expire = time_uptime + V_dyn_syn_lifetime;
 403                         break;
 404
 405                 case BOTH_SYN:                  /* move to established */
 406                 case BOTH_SYN | TH_FIN:         /* one side tries to close */
 407                 case BOTH_SYN | (TH_FIN << 8):
 408 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
 409                         if (tcp == NULL)
 410                                 break;
 411
 412                         ack = ntohl(tcp->th_ack);
 413                         if (dir == MATCH_FORWARD) {
 414                                 if (q->ack_fwd == 0 ||
 415                                     _SEQ_GE(ack, q->ack_fwd)) {
 416                                         q->ack_fwd = ack;
 417                                         q->state |= ACK_FWD;
 418                                 }
 419                         } else {
 420                                 if (q->ack_rev == 0 ||
 421                                     _SEQ_GE(ack, q->ack_rev)) {
 422                                         q->ack_rev = ack;
 423                                         q->state |= ACK_REV;
 424                                 }
 425                         }
 426                         if ((q->state & (ACK_FWD | ACK_REV)) ==
 427                             (ACK_FWD | ACK_REV)) {
 428                                 q->expire = time_uptime + V_dyn_ack_lifetime;
 429                                 q->state &= ~(ACK_FWD | ACK_REV);
 430                         }
 431                         break;
 432
 433                 case BOTH_SYN | BOTH_FIN:       /* both sides closed */
 434                         if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
 435                                 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
 436                         q->expire = time_uptime + V_dyn_fin_lifetime;
 437                         break;
 438
 439                 default:
 440 #if 0
 441                         /*
 442                          * reset or some invalid combination, but can also
 443                          * occur if we use keep-state the wrong way.
 444                          */
 445                         if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
 446                                 printf("invalid state: 0x%x\n", q->state);
 447 #endif
 448                         if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
 449                                 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
 450                         q->expire = time_uptime + V_dyn_rst_lifetime;
 451                         break;
 452                 }
 453         } else if (pkt->proto == IPPROTO_UDP) {
 454                 q->expire = time_uptime + V_dyn_udp_lifetime;
 455         } else {
 456                 /* other protocols */
 457                 q->expire = time_uptime + V_dyn_short_lifetime;
 458         }
 459 done:
 460         if (match_direction != NULL)
 461                 *match_direction = dir;
 462         return (q);
 463 }
 464
 465 ipfw_dyn_rule *
 466 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
 467     struct tcphdr *tcp)
 468 {
 469         ipfw_dyn_rule *q;
 470         int i;
 471
 472         i = hash_packet(pkt, V_curr_dyn_buckets);
 473
 474         IPFW_BUCK_LOCK(i);
 475         q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp);
 476         if (q == NULL)
 477                 IPFW_BUCK_UNLOCK(i);
 478         /* NB: return table locked when q is not NULL */
 479         return q;
 480 }
 481
 482 /*
 483  * Unlock bucket mtx
 484  * @p - pointer to dynamic rule
 485  */
 486 void
 487 ipfw_dyn_unlock(ipfw_dyn_rule *q)
 488 {
 489
 490         IPFW_BUCK_UNLOCK(q->bucket);
 491 }
 492
 493 static int
 494 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
 495 {
 496         int i, k, nbuckets_old;
 497         ipfw_dyn_rule *q;
 498         struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
 499
 500         /* Check if given number is power of 2 and less than 64k */
 501         if ((nbuckets > 65536) || (!powerof2(nbuckets)))
 502                 return 1;
 503
 504         CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
 505             V_curr_dyn_buckets, nbuckets);
 506
 507         /* Allocate and initialize new hash */
 508         dyn_v = malloc(nbuckets * sizeof(ipfw_dyn_rule), M_IPFW,
 509             M_WAITOK | M_ZERO);
 510
 511         for (i = 0 ; i < nbuckets; i++)
 512                 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
 513
 514         /*
 515          * Call upper half lock, as get_map() do to ease
 516          * read-only access to dynamic rules hash from sysctl
 517          */
 518         IPFW_UH_WLOCK(chain);
 519
 520         /*
 521          * Acquire chain write lock to permit hash access
 522          * for main traffic path without additional locks
 523          */
 524         IPFW_WLOCK(chain);
 525
 526         /* Save old values */
 527         nbuckets_old = V_curr_dyn_buckets;
 528         dyn_v_old = V_ipfw_dyn_v;
 529
 530         /* Skip relinking if array is not set up */
 531         if (V_ipfw_dyn_v == NULL)
 532                 V_curr_dyn_buckets = 0;
 533
 534         /* Re-link all dynamic states */
 535         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
 536                 while (V_ipfw_dyn_v[i].head != NULL) {
 537                         /* Remove from current chain */
 538                         q = V_ipfw_dyn_v[i].head;
 539                         V_ipfw_dyn_v[i].head = q->next;
 540
 541                         /* Get new hash value */
 542                         k = hash_packet(&q->id, nbuckets);
 543                         q->bucket = k;
 544                         /* Add to the new head */
 545                         q->next = dyn_v[k].head;
 546                         dyn_v[k].head = q;
 547              }
 548         }
 549
 550         /* Update current pointers/buckets values */
 551         V_curr_dyn_buckets = nbuckets;
 552         V_ipfw_dyn_v = dyn_v;
 553
 554         IPFW_WUNLOCK(chain);
 555
 556         IPFW_UH_WUNLOCK(chain);
 557
 558         /* Start periodic callout on initial creation */
 559         if (dyn_v_old == NULL) {
 560                 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
 561                 return (0);
 562         }
 563
 564         /* Destroy all mutexes */
 565         for (i = 0 ; i < nbuckets_old ; i++)
 566                 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
 567
 568         /* Free old hash */
 569         free(dyn_v_old, M_IPFW);
 570
 571         return 0;
 572 }
 573
 574 /**
 575  * Install state of type 'type' for a dynamic session.
 576  * The hash table contains two type of rules:
 577  * - regular rules (O_KEEP_STATE)
 578  * - rules for sessions with limited number of sess per user
 579  *   (O_LIMIT). When they are created, the parent is
 580  *   increased by 1, and decreased on delete. In this case,
 581  *   the third parameter is the parent rule and not the chain.
 582  * - "parent" rules for the above (O_LIMIT_PARENT).
 583  */
 584 static ipfw_dyn_rule *
 585 add_dyn_rule(struct ipfw_flow_id *id, int i, u_int8_t dyn_type, struct ip_fw *rule)
 586 {
 587         ipfw_dyn_rule *r;
 588
 589         IPFW_BUCK_ASSERT(i);
 590
 591         r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
 592         if (r == NULL) {
 593                 if (last_log != time_uptime) {
 594                         last_log = time_uptime;
 595                         log(LOG_DEBUG,
 596                             "ipfw: Cannot allocate dynamic state, "
 597                             "consider increasing net.inet.ip.fw.dyn_max\n");
 598                 }
 599                 return NULL;
 600         }
 601         ipfw_dyn_count++;
 602
 603         /*
 604          * refcount on parent is already incremented, so
 605          * it is safe to use parent unlocked.
 606          */
 607         if (dyn_type == O_LIMIT) {
 608                 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
 609                 if ( parent->dyn_type != O_LIMIT_PARENT)
 610                         panic("invalid parent");
 611                 r->parent = parent;
 612                 rule = parent->rule;
 613         }
 614
 615         r->id = *id;
 616         r->expire = time_uptime + V_dyn_syn_lifetime;
 617         r->rule = rule;
 618         r->dyn_type = dyn_type;
 619         IPFW_ZERO_DYN_COUNTER(r);
 620         r->count = 0;
 621
 622         r->bucket = i;
 623         r->next = V_ipfw_dyn_v[i].head;
 624         V_ipfw_dyn_v[i].head = r;
 625         DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
 626         return r;
 627 }
 628
 629 /**
 630  * lookup dynamic parent rule using pkt and rule as search keys.
 631  * If the lookup fails, then install one.
 632  */
 633 static ipfw_dyn_rule *
 634 lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule)
 635 {
 636         ipfw_dyn_rule *q;
 637         int i, is_v6;
 638
 639         is_v6 = IS_IP6_FLOW_ID(pkt);
 640         i = hash_packet( pkt, V_curr_dyn_buckets );
 641         *pindex = i;
 642         IPFW_BUCK_LOCK(i);
 643         for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
 644                 if (q->dyn_type == O_LIMIT_PARENT &&
 645                     rule== q->rule &&
 646                     pkt->proto == q->id.proto &&
 647                     pkt->src_port == q->id.src_port &&
 648                     pkt->dst_port == q->id.dst_port &&
 649                     (
 650                         (is_v6 &&
 651                          IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
 652                                 &(q->id.src_ip6)) &&
 653                          IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
 654                                 &(q->id.dst_ip6))) ||
 655                         (!is_v6 &&
 656                          pkt->src_ip == q->id.src_ip &&
 657                          pkt->dst_ip == q->id.dst_ip)
 658                     )
 659                 ) {
 660                         q->expire = time_uptime + V_dyn_short_lifetime;
 661                         DEB(print_dyn_rule(pkt, q->dyn_type,
 662                             "lookup_dyn_parent found", "");)
 663                         return q;
 664                 }
 665
 666         /* Add virtual limiting rule */
 667         return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule);
 668 }
 669
 670 /**
 671  * Install dynamic state for rule type cmd->o.opcode
 672  *
 673  * Returns 1 (failure) if state is not installed because of errors or because
 674  * session limitations are enforced.
 675  */
 676 int
 677 ipfw_install_state(struct ip_fw_chain *chain, struct ip_fw *rule,
 678     ipfw_insn_limit *cmd, struct ip_fw_args *args, uint32_t tablearg)
 679 {
 680         ipfw_dyn_rule *q;
 681         int i;
 682
 683         DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");)
 684
 685         i = hash_packet(&args->f_id, V_curr_dyn_buckets);
 686
 687         IPFW_BUCK_LOCK(i);
 688
 689         q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
 690
 691         if (q != NULL) {        /* should never occur */
 692                 DEB(
 693                 if (last_log != time_uptime) {
 694                         last_log = time_uptime;
 695                         printf("ipfw: %s: entry already present, done\n",
 696                             __func__);
 697                 })
 698                 IPFW_BUCK_UNLOCK(i);
 699                 return (0);
 700         }
 701
 702         /*
 703          * State limiting is done via uma(9) zone limiting.
 704          * Save pointer to newly-installed rule and reject
 705          * packet if add_dyn_rule() returned NULL.
 706          * Note q is currently set to NULL.
 707          */
 708
 709         switch (cmd->o.opcode) {
 710         case O_KEEP_STATE:      /* bidir rule */
 711                 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
 712                 break;
 713
 714         case O_LIMIT: {         /* limit number of sessions */
 715                 struct ipfw_flow_id id;
 716                 ipfw_dyn_rule *parent;
 717                 uint32_t conn_limit;
 718                 uint16_t limit_mask = cmd->limit_mask;
 719                 int pindex;
 720
 721                 conn_limit = IP_FW_ARG_TABLEARG(chain, cmd->conn_limit, limit);
 722
 723                 DEB(
 724                 if (cmd->conn_limit == IP_FW_TARG)
 725                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
 726                             "(tablearg)\n", __func__, conn_limit);
 727                 else
 728                         printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
 729                             __func__, conn_limit);
 730                 )
 731
 732                 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
 733                 id.proto = args->f_id.proto;
 734                 id.addr_type = args->f_id.addr_type;
 735                 id.fib = M_GETFIB(args->m);
 736
 737                 if (IS_IP6_FLOW_ID (&(args->f_id))) {
 738                         if (limit_mask & DYN_SRC_ADDR)
 739                                 id.src_ip6 = args->f_id.src_ip6;
 740                         if (limit_mask & DYN_DST_ADDR)
 741                                 id.dst_ip6 = args->f_id.dst_ip6;
 742                 } else {
 743                         if (limit_mask & DYN_SRC_ADDR)
 744                                 id.src_ip = args->f_id.src_ip;
 745                         if (limit_mask & DYN_DST_ADDR)
 746                                 id.dst_ip = args->f_id.dst_ip;
 747                 }
 748                 if (limit_mask & DYN_SRC_PORT)
 749                         id.src_port = args->f_id.src_port;
 750                 if (limit_mask & DYN_DST_PORT)
 751                         id.dst_port = args->f_id.dst_port;
 752
 753                 /*
 754                  * We have to release lock for previous bucket to
 755                  * avoid possible deadlock
 756                  */
 757                 IPFW_BUCK_UNLOCK(i);
 758
 759                 if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) {
 760                         printf("ipfw: %s: add parent failed\n", __func__);
 761                         IPFW_BUCK_UNLOCK(pindex);
 762                         return (1);
 763                 }
 764
 765                 if (parent->count >= conn_limit) {
 766                         if (V_fw_verbose && last_log != time_uptime) {
 767                                 last_log = time_uptime;
 768                                 char sbuf[24];
 769                                 last_log = time_uptime;
 770                                 snprintf(sbuf, sizeof(sbuf),
 771                                     "%d drop session",
 772                                     parent->rule->rulenum);
 773                                 print_dyn_rule_flags(&args->f_id,
 774                                     cmd->o.opcode,
 775                                     LOG_SECURITY | LOG_DEBUG,
 776                                     sbuf, "too many entries");
 777                         }
 778                         IPFW_BUCK_UNLOCK(pindex);
 779                         return (1);
 780                 }
 781                 /* Increment counter on parent */
 782                 parent->count++;
 783                 IPFW_BUCK_UNLOCK(pindex);
 784
 785                 IPFW_BUCK_LOCK(i);
 786                 q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent);
 787                 if (q == NULL) {
 788                         /* Decrement index and notify caller */
 789                         IPFW_BUCK_UNLOCK(i);
 790                         IPFW_BUCK_LOCK(pindex);
 791                         parent->count--;
 792                         IPFW_BUCK_UNLOCK(pindex);
 793                         return (1);
 794                 }
 795                 break;
 796         }
 797         default:
 798                 printf("ipfw: %s: unknown dynamic rule type %u\n",
 799                     __func__, cmd->o.opcode);
 800         }
 801
 802         if (q == NULL) {
 803                 IPFW_BUCK_UNLOCK(i);
 804                 return (1);     /* Notify caller about failure */
 805         }
 806
 807         /* XXX just set lifetime */
 808         lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
 809
 810         IPFW_BUCK_UNLOCK(i);
 811         return (0);
 812 }
 813
 814 /*
 815  * Generate a TCP packet, containing either a RST or a keepalive.
 816  * When flags & TH_RST, we are sending a RST packet, because of a
 817  * "reset" action matched the packet.
 818  * Otherwise we are sending a keepalive, and flags & TH_
 819  * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
 820  * so that MAC can label the reply appropriately.
 821  */
 822 struct mbuf *
 823 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
 824     u_int32_t ack, int flags)
 825 {
 826         struct mbuf *m = NULL;          /* stupid compiler */
 827         int len, dir;
 828         struct ip *h = NULL;            /* stupid compiler */
 829 #ifdef INET6
 830         struct ip6_hdr *h6 = NULL;
 831 #endif
 832         struct tcphdr *th = NULL;
 833
 834         MGETHDR(m, M_NOWAIT, MT_DATA);
 835         if (m == NULL)
 836                 return (NULL);
 837
 838         M_SETFIB(m, id->fib);
 839 #ifdef MAC
 840         if (replyto != NULL)
 841                 mac_netinet_firewall_reply(replyto, m);
 842         else
 843                 mac_netinet_firewall_send(m);
 844 #else
 845         (void)replyto;          /* don't warn about unused arg */
 846 #endif
 847
 848         switch (id->addr_type) {
 849         case 4:
 850                 len = sizeof(struct ip) + sizeof(struct tcphdr);
 851                 break;
 852 #ifdef INET6
 853         case 6:
 854                 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
 855                 break;
 856 #endif
 857         default:
 858                 /* XXX: log me?!? */
 859                 FREE_PKT(m);
 860                 return (NULL);
 861         }
 862         dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
 863
 864         m->m_data += max_linkhdr;
 865         m->m_flags |= M_SKIP_FIREWALL;
 866         m->m_pkthdr.len = m->m_len = len;
 867         m->m_pkthdr.rcvif = NULL;
 868         bzero(m->m_data, len);
 869
 870         switch (id->addr_type) {
 871         case 4:
 872                 h = mtod(m, struct ip *);
 873
 874                 /* prepare for checksum */
 875                 h->ip_p = IPPROTO_TCP;
 876                 h->ip_len = htons(sizeof(struct tcphdr));
 877                 if (dir) {
 878                         h->ip_src.s_addr = htonl(id->src_ip);
 879                         h->ip_dst.s_addr = htonl(id->dst_ip);
 880                 } else {
 881                         h->ip_src.s_addr = htonl(id->dst_ip);
 882                         h->ip_dst.s_addr = htonl(id->src_ip);
 883                 }
 884
 885                 th = (struct tcphdr *)(h + 1);
 886                 break;
 887 #ifdef INET6
 888         case 6:
 889                 h6 = mtod(m, struct ip6_hdr *);
 890
 891                 /* prepare for checksum */
 892                 h6->ip6_nxt = IPPROTO_TCP;
 893                 h6->ip6_plen = htons(sizeof(struct tcphdr));
 894                 if (dir) {
 895                         h6->ip6_src = id->src_ip6;
 896                         h6->ip6_dst = id->dst_ip6;
 897                 } else {
 898                         h6->ip6_src = id->dst_ip6;
 899                         h6->ip6_dst = id->src_ip6;
 900                 }
 901
 902                 th = (struct tcphdr *)(h6 + 1);
 903                 break;
 904 #endif
 905         }
 906
 907         if (dir) {
 908                 th->th_sport = htons(id->src_port);
 909                 th->th_dport = htons(id->dst_port);
 910         } else {
 911                 th->th_sport = htons(id->dst_port);
 912                 th->th_dport = htons(id->src_port);
 913         }
 914         th->th_off = sizeof(struct tcphdr) >> 2;
 915
 916         if (flags & TH_RST) {
 917                 if (flags & TH_ACK) {
 918                         th->th_seq = htonl(ack);
 919                         th->th_flags = TH_RST;
 920                 } else {
 921                         if (flags & TH_SYN)
 922                                 seq++;
 923                         th->th_ack = htonl(seq);
 924                         th->th_flags = TH_RST | TH_ACK;
 925                 }
 926         } else {
 927                 /*
 928                  * Keepalive - use caller provided sequence numbers
 929                  */
 930                 th->th_seq = htonl(seq);
 931                 th->th_ack = htonl(ack);
 932                 th->th_flags = TH_ACK;
 933         }
 934
 935         switch (id->addr_type) {
 936         case 4:
 937                 th->th_sum = in_cksum(m, len);
 938
 939                 /* finish the ip header */
 940                 h->ip_v = 4;
 941                 h->ip_hl = sizeof(*h) >> 2;
 942                 h->ip_tos = IPTOS_LOWDELAY;
 943                 h->ip_off = htons(0);
 944                 h->ip_len = htons(len);
 945                 h->ip_ttl = V_ip_defttl;
 946                 h->ip_sum = 0;
 947                 break;
 948 #ifdef INET6
 949         case 6:
 950                 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
 951                     sizeof(struct tcphdr));
 952
 953                 /* finish the ip6 header */
 954                 h6->ip6_vfc |= IPV6_VERSION;
 955                 h6->ip6_hlim = IPV6_DEFHLIM;
 956                 break;
 957 #endif
 958         }
 959
 960         return (m);
 961 }
 962
 963 /*
 964  * Queue keepalive packets for given dynamic rule
 965  */
 966 static struct mbuf **
 967 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
 968 {
 969         struct mbuf *m_rev, *m_fwd;
 970
 971         m_rev = (q->state & ACK_REV) ? NULL :
 972             ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
 973         m_fwd = (q->state & ACK_FWD) ? NULL :
 974             ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
 975
 976         if (m_rev != NULL) {
 977                 *mtailp = m_rev;
 978                 mtailp = &(*mtailp)->m_nextpkt;
 979         }
 980         if (m_fwd != NULL) {
 981                 *mtailp = m_fwd;
 982                 mtailp = &(*mtailp)->m_nextpkt;
 983         }
 984
 985         return (mtailp);
 986 }
 987
 988 /*
 989  * This procedure is used to perform various maintance
 990  * on dynamic hash list. Currently it is called every second.
 991  */
 992 static void
 993 ipfw_dyn_tick(void * vnetx)
 994 {
 995         struct ip_fw_chain *chain;
 996         int check_ka = 0;
 997 #ifdef VIMAGE
 998         struct vnet *vp = vnetx;
 999 #endif
1000
1001         CURVNET_SET(vp);
1002
1003         chain = &V_layer3_chain;
1004
1005         /* Run keepalive checks every keepalive_period iff ka is enabled */
1006         if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
1007             (V_dyn_keepalive != 0)) {
1008                 V_dyn_keepalive_last = time_uptime;
1009                 check_ka = 1;
1010         }
1011
1012         check_dyn_rules(chain, NULL, check_ka, 1);
1013
1014         callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
1015
1016         CURVNET_RESTORE();
1017 }
1018
1019
1020 /*
1021  * Walk thru all dynamic states doing generic maintance:
1022  * 1) free expired states
1023  * 2) free all states based on deleted rule / set
1024  * 3) send keepalives for states if needed
1025  *
1026  * @chain - pointer to current ipfw rules chain
1027  * @rule - delete all states originated by given rule if != NULL
1028  * @set - delete all states originated by any rule in set @set if != RESVD_SET
1029  * @check_ka - perform checking/sending keepalives
1030  * @timer - indicate call from timer routine.
1031  *
1032  * Timer routine must call this function unlocked to permit
1033  * sending keepalives/resizing table.
1034  *
1035  * Others has to call function with IPFW_UH_WLOCK held.
1036  * Additionally, function assume that dynamic rule/set is
1037  * ALREADY deleted so no new states can be generated by
1038  * 'deleted' rules.
1039  *
1040  * Write lock is needed to ensure that unused parent rules
1041  * are not freed by other instance (see stage 2, 3)
1042  */
1043 static void
1044 check_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt,
1045     int check_ka, int timer)
1046 {
1047         struct mbuf *m0, *m, *mnext, **mtailp;
1048         struct ip *h;
1049         int i, dyn_count, new_buckets = 0, max_buckets;
1050         int expired = 0, expired_limits = 0, parents = 0, total = 0;
1051         ipfw_dyn_rule *q, *q_prev, *q_next;
1052         ipfw_dyn_rule *exp_head, **exptailp;
1053         ipfw_dyn_rule *exp_lhead, **expltailp;
1054
1055         KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1056             __func__));
1057
1058         /* Avoid possible LOR */
1059         KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1060             __func__));
1061
1062         /*
1063          * Do not perform any checks if we currently have no dynamic states
1064          */
1065         if (DYN_COUNT == 0)
1066                 return;
1067
1068         /* Expired states */
1069         exp_head = NULL;
1070         exptailp = &exp_head;
1071
1072         /* Expired limit states */
1073         exp_lhead = NULL;
1074         expltailp = &exp_lhead;
1075
1076         /*
1077          * We make a chain of packets to go out here -- not deferring
1078          * until after we drop the IPFW dynamic rule lock would result
1079          * in a lock order reversal with the normal packet input -> ipfw
1080          * call stack.
1081          */
1082         m0 = NULL;
1083         mtailp = &m0;
1084
1085         /* Protect from hash resizing */
1086         if (timer != 0)
1087                 IPFW_UH_WLOCK(chain);
1088         else
1089                 IPFW_UH_WLOCK_ASSERT(chain);
1090
1091 #define NEXT_RULE()     { q_prev = q; q = q->next ; continue; }
1092
1093         /* Stage 1: perform requested deletion */
1094         for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1095                 IPFW_BUCK_LOCK(i);
1096                 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1097                         /* account every rule */
1098                         total++;
1099
1100                         /* Skip parent rules at all */
1101                         if (q->dyn_type == O_LIMIT_PARENT) {
1102                                 parents++;
1103                                 NEXT_RULE();
1104                         }
1105
1106                         /*
1107                          * Remove rules which are:
1108                          * 1) expired
1109                          * 2) matches deletion range
1110                          */
1111                         if ((TIME_LEQ(q->expire, time_uptime)) ||
1112                             (rt != NULL && ipfw_match_range(q->rule, rt))) {
1113                                 if (TIME_LE(time_uptime, q->expire) &&
1114                                     q->dyn_type == O_KEEP_STATE &&
1115                                     V_dyn_keep_states != 0) {
1116                                         /*
1117                                          * Do not delete state if
1118                                          * it is not expired and
1119                                          * dyn_keep_states is ON.
1120                                          * However we need to re-link it
1121                                          * to any other stable rule
1122                                          */
1123                                         q->rule = chain->default_rule;
1124                                         NEXT_RULE();
1125                                 }
1126
1127                                 /* Unlink q from current list */
1128                                 q_next = q->next;
1129                                 if (q == V_ipfw_dyn_v[i].head)
1130                                         V_ipfw_dyn_v[i].head = q_next;
1131                                 else
1132                                         q_prev->next = q_next;
1133
1134                                 q->next = NULL;
1135
1136                                 /* queue q to expire list */
1137                                 if (q->dyn_type != O_LIMIT) {
1138                                         *exptailp = q;
1139                                         exptailp = &(*exptailp)->next;
1140                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1141                                             "unlink entry", "left");
1142                                         )
1143                                 } else {
1144                                         /* Separate list for limit rules */
1145                                         *expltailp = q;
1146                                         expltailp = &(*expltailp)->next;
1147                                         expired_limits++;
1148                                         DEB(print_dyn_rule(&q->id, q->dyn_type,
1149                                             "unlink limit entry", "left");
1150                                         )
1151                                 }
1152
1153                                 q = q_next;
1154                                 expired++;
1155                                 continue;
1156                         }
1157
1158                         /*
1159                          * Check if we need to send keepalive:
1160                          * we need to ensure if is time to do KA,
1161                          * this is established TCP session, and
1162                          * expire time is within keepalive interval
1163                          */
1164                         if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1165                             ((q->state & BOTH_SYN) == BOTH_SYN) &&
1166                             (TIME_LEQ(q->expire, time_uptime +
1167                               V_dyn_keepalive_interval)))
1168                                 mtailp = ipfw_dyn_send_ka(mtailp, q);
1169
1170                         NEXT_RULE();
1171                 }
1172                 IPFW_BUCK_UNLOCK(i);
1173         }
1174
1175         /* Stage 2: decrement counters from O_LIMIT parents */
1176         if (expired_limits != 0) {
1177                 /*
1178                  * XXX: Note that deleting set with more than one
1179                  * heavily-used LIMIT rules can result in overwhelming
1180                  * locking due to lack of per-hash value sorting
1181                  *
1182                  * We should probably think about:
1183                  * 1) pre-allocating hash of size, say,
1184                  * MAX(16, V_curr_dyn_buckets / 1024)
1185                  * 2) checking if expired_limits is large enough
1186                  * 3) If yes, init hash (or its part), re-link
1187                  * current list and start decrementing procedure in
1188                  * each bucket separately
1189                  */
1190
1191                 /*
1192                  * Small optimization: do not unlock bucket until
1193                  * we see the next item resides in different bucket
1194                  */
1195                 if (exp_lhead != NULL) {
1196                         i = exp_lhead->parent->bucket;
1197                         IPFW_BUCK_LOCK(i);
1198                 }
1199                 for (q = exp_lhead; q != NULL; q = q->next) {
1200                         if (i != q->parent->bucket) {
1201                                 IPFW_BUCK_UNLOCK(i);
1202                                 i = q->parent->bucket;
1203                                 IPFW_BUCK_LOCK(i);
1204                         }
1205
1206                         /* Decrease parent refcount */
1207                         q->parent->count--;
1208                 }
1209                 if (exp_lhead != NULL)
1210                         IPFW_BUCK_UNLOCK(i);
1211         }
1212
1213         /*
1214          * We protectet ourselves from unused parent deletion
1215          * (from the timer function) by holding UH write lock.
1216          */
1217
1218         /* Stage 3: remove unused parent rules */
1219         if ((parents != 0) && (expired != 0)) {
1220                 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1221                         IPFW_BUCK_LOCK(i);
1222                         for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1223                                 if (q->dyn_type != O_LIMIT_PARENT)
1224                                         NEXT_RULE();
1225
1226                                 if (q->count != 0)
1227                                         NEXT_RULE();
1228
1229                                 /* Parent rule without consumers */
1230
1231                                 /* Unlink q from current list */
1232                                 q_next = q->next;
1233                                 if (q == V_ipfw_dyn_v[i].head)
1234                                         V_ipfw_dyn_v[i].head = q_next;
1235                                 else
1236                                         q_prev->next = q_next;
1237
1238                                 q->next = NULL;
1239
1240                                 /* Add to expired list */
1241                                 *exptailp = q;
1242                                 exptailp = &(*exptailp)->next;
1243
1244                                 DEB(print_dyn_rule(&q->id, q->dyn_type,
1245                                     "unlink parent entry", "left");
1246                                 )
1247
1248                                 expired++;
1249
1250                                 q = q_next;
1251                         }
1252                         IPFW_BUCK_UNLOCK(i);
1253                 }
1254         }
1255
1256 #undef NEXT_RULE
1257
1258         if (timer != 0) {
1259                 /*
1260                  * Check if we need to resize hash:
1261                  * if current number of states exceeds number of buckes in hash,
1262                  * grow hash size to the minimum power of 2 which is bigger than
1263                  * current states count. Limit hash size by 64k.
1264                  */
1265                 max_buckets = (V_dyn_buckets_max > 65536) ?
1266                     65536 : V_dyn_buckets_max;
1267
1268                 dyn_count = DYN_COUNT;
1269
1270                 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1271                     (dyn_count < max_buckets)) {
1272                         new_buckets = V_curr_dyn_buckets;
1273                         while (new_buckets < dyn_count) {
1274                                 new_buckets *= 2;
1275
1276                                 if (new_buckets >= max_buckets)
1277                                         break;
1278                         }
1279                 }
1280
1281                 IPFW_UH_WUNLOCK(chain);
1282         }
1283
1284         /* Finally delete old states ad limits if any */
1285         for (q = exp_head; q != NULL; q = q_next) {
1286                 q_next = q->next;
1287                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1288                 ipfw_dyn_count--;
1289         }
1290
1291         for (q = exp_lhead; q != NULL; q = q_next) {
1292                 q_next = q->next;
1293                 uma_zfree(V_ipfw_dyn_rule_zone, q);
1294                 ipfw_dyn_count--;
1295         }
1296
1297         /*
1298          * The rest code MUST be called from timer routine only
1299          * without holding any locks
1300          */
1301         if (timer == 0)
1302                 return;
1303
1304         /* Send keepalive packets if any */
1305         for (m = m0; m != NULL; m = mnext) {
1306                 mnext = m->m_nextpkt;
1307                 m->m_nextpkt = NULL;
1308                 h = mtod(m, struct ip *);
1309                 if (h->ip_v == 4)
1310                         ip_output(m, NULL, NULL, 0, NULL, NULL);
1311 #ifdef INET6
1312                 else
1313                         ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1314 #endif
1315         }
1316
1317         /* Run table resize without holding any locks */
1318         if (new_buckets != 0)
1319                 resize_dynamic_table(chain, new_buckets);
1320 }
1321
1322 /*
1323  * Deletes all dynamic rules originated by given rule or all rules in
1324  * given set. Specify RESVD_SET to indicate set should not be used.
1325  * @chain - pointer to current ipfw rules chain
1326  * @rr - delete all states originated by rules in matched range.
1327  *
1328  * Function has to be called with IPFW_UH_WLOCK held.
1329  * Additionally, function assume that dynamic rule/set is
1330  * ALREADY deleted so no new states can be generated by
1331  * 'deleted' rules.
1332  */
1333 void
1334 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, ipfw_range_tlv *rt)
1335 {
1336
1337         check_dyn_rules(chain, rt, 0, 0);
1338 }
1339
1340 /*
1341  * Check if rule contains at least one dynamic opcode.
1342  *
1343  * Returns 1 if such opcode is found, 0 otherwise.
1344  */
1345 int
1346 ipfw_is_dyn_rule(struct ip_fw *rule)
1347 {
1348         int cmdlen, l;
1349         ipfw_insn *cmd;
1350
1351         l = rule->cmd_len;
1352         cmd = rule->cmd;
1353         cmdlen = 0;
1354         for ( ; l > 0 ; l -= cmdlen, cmd += cmdlen) {
1355                 cmdlen = F_LEN(cmd);
1356
1357                 switch (cmd->opcode) {
1358                 case O_LIMIT:
1359                 case O_KEEP_STATE:
1360                 case O_PROBE_STATE:
1361                 case O_CHECK_STATE:
1362                         return (1);
1363                 }
1364         }
1365
1366         return (0);
1367 }
1368
1369 void
1370 ipfw_dyn_init(struct ip_fw_chain *chain)
1371 {
1372
1373         V_ipfw_dyn_v = NULL;
1374         V_dyn_buckets_max = 256; /* must be power of 2 */
1375         V_curr_dyn_buckets = 256; /* must be power of 2 */
1376
1377         V_dyn_ack_lifetime = 300;
1378         V_dyn_syn_lifetime = 20;
1379         V_dyn_fin_lifetime = 1;
1380         V_dyn_rst_lifetime = 1;
1381         V_dyn_udp_lifetime = 10;
1382         V_dyn_short_lifetime = 5;
1383
1384         V_dyn_keepalive_interval = 20;
1385         V_dyn_keepalive_period = 5;
1386         V_dyn_keepalive = 1;    /* do send keepalives */
1387         V_dyn_keepalive_last = time_uptime;
1388
1389         V_dyn_max = 16384; /* max # of dynamic rules */
1390
1391         V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1392             sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1393             UMA_ALIGN_PTR, 0);
1394
1395         /* Enforce limit on dynamic rules */
1396         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1397
1398         callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1399
1400         /*
1401          * This can potentially be done on first dynamic rule
1402          * being added to chain.
1403          */
1404         resize_dynamic_table(chain, V_curr_dyn_buckets);
1405 }
1406
1407 void
1408 ipfw_dyn_uninit(int pass)
1409 {
1410         int i;
1411
1412         if (pass == 0) {
1413                 callout_drain(&V_ipfw_timeout);
1414                 return;
1415         }
1416
1417         if (V_ipfw_dyn_v != NULL) {
1418                 /*
1419                  * Skip deleting all dynamic states -
1420                  * uma_zdestroy() does this more efficiently;
1421                  */
1422
1423                 /* Destroy all mutexes */
1424                 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1425                         IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1426                 free(V_ipfw_dyn_v, M_IPFW);
1427                 V_ipfw_dyn_v = NULL;
1428         }
1429
1430         uma_zdestroy(V_ipfw_dyn_rule_zone);
1431 }
1432
1433 #ifdef SYSCTL_NODE
1434 /*
1435  * Get/set maximum number of dynamic states in given VNET instance.
1436  */
1437 static int
1438 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1439 {
1440         int error;
1441         unsigned int nstates;
1442
1443         nstates = V_dyn_max;
1444
1445         error = sysctl_handle_int(oidp, &nstates, 0, req);
1446         /* Read operation or some error */
1447         if ((error != 0) || (req->newptr == NULL))
1448                 return (error);
1449
1450         V_dyn_max = nstates;
1451         uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1452
1453         return (0);
1454 }
1455
1456 /*
1457  * Get current number of dynamic states in given VNET instance.
1458  */
1459 static int
1460 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1461 {
1462         int error;
1463         unsigned int nstates;
1464
1465         nstates = DYN_COUNT;
1466
1467         error = sysctl_handle_int(oidp, &nstates, 0, req);
1468
1469         return (error);
1470 }
1471 #endif
1472
1473 /*
1474  * Returns size of dynamic states in legacy format
1475  */
1476 int
1477 ipfw_dyn_len(void)
1478 {
1479
1480         return (V_ipfw_dyn_v == NULL) ? 0 :
1481                 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1482 }
1483
1484 /*
1485  * Returns number of dynamic states.
1486  * Used by dump format v1 (current).
1487  */
1488 int
1489 ipfw_dyn_get_count(void)
1490 {
1491
1492         return (V_ipfw_dyn_v == NULL) ? 0 : DYN_COUNT;
1493 }
1494
1495 static void
1496 export_dyn_rule(ipfw_dyn_rule *src, ipfw_dyn_rule *dst)
1497 {
1498
1499         memcpy(dst, src, sizeof(*src));
1500         memcpy(&(dst->rule), &(src->rule->rulenum), sizeof(src->rule->rulenum));
1501         /*
1502          * store set number into high word of
1503          * dst->rule pointer.
1504          */
1505         memcpy((char *)&dst->rule + sizeof(src->rule->rulenum),
1506             &(src->rule->set), sizeof(src->rule->set));
1507         /*
1508          * store a non-null value in "next".
1509          * The userland code will interpret a
1510          * NULL here as a marker
1511          * for the last dynamic rule.
1512          */
1513         memcpy(&dst->next, &dst, sizeof(dst));
1514         dst->expire =
1515             TIME_LEQ(dst->expire, time_uptime) ?  0 : dst->expire - time_uptime;
1516 }
1517
1518 /*
1519  * Fills int buffer given by @sd with dynamic states.
1520  * Used by dump format v1 (current).
1521  *
1522  * Returns 0 on success.
1523  */
1524 int
1525 ipfw_dump_states(struct ip_fw_chain *chain, struct sockopt_data *sd)
1526 {
1527         ipfw_dyn_rule *p;
1528         ipfw_obj_dyntlv *dst, *last;
1529         ipfw_obj_ctlv *ctlv;
1530         int i;
1531         size_t sz;
1532
1533         if (V_ipfw_dyn_v == NULL)
1534                 return (0);
1535
1536         IPFW_UH_RLOCK_ASSERT(chain);
1537
1538         ctlv = (ipfw_obj_ctlv *)ipfw_get_sopt_space(sd, sizeof(*ctlv));
1539         if (ctlv == NULL)
1540                 return (ENOMEM);
1541         sz = sizeof(ipfw_obj_dyntlv);
1542         ctlv->head.type = IPFW_TLV_DYNSTATE_LIST;
1543         ctlv->objsize = sz;
1544         last = NULL;
1545
1546         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1547                 IPFW_BUCK_LOCK(i);
1548                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1549                         dst = (ipfw_obj_dyntlv *)ipfw_get_sopt_space(sd, sz);
1550                         if (dst == NULL) {
1551                                 IPFW_BUCK_UNLOCK(i);
1552                                 return (ENOMEM);
1553                         }
1554
1555                         export_dyn_rule(p, &dst->state);
1556                         dst->head.length = sz;
1557                         dst->head.type = IPFW_TLV_DYN_ENT;
1558                         last = dst;
1559                 }
1560                 IPFW_BUCK_UNLOCK(i);
1561         }
1562
1563         if (last != NULL) /* mark last dynamic rule */
1564                 last->head.flags = IPFW_DF_LAST;
1565
1566         return (0);
1567 }
1568
1569 /*
1570  * Fill given buffer with dynamic states (legacy format).
1571  * IPFW_UH_RLOCK has to be held while calling.
1572  */
1573 void
1574 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1575 {
1576         ipfw_dyn_rule *p, *last = NULL;
1577         char *bp;
1578         int i;
1579
1580         if (V_ipfw_dyn_v == NULL)
1581                 return;
1582         bp = *pbp;
1583
1584         IPFW_UH_RLOCK_ASSERT(chain);
1585
1586         for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1587                 IPFW_BUCK_LOCK(i);
1588                 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1589                         if (bp + sizeof *p <= ep) {
1590                                 ipfw_dyn_rule *dst =
1591                                         (ipfw_dyn_rule *)bp;
1592
1593                                 export_dyn_rule(p, dst);
1594                                 last = dst;
1595                                 bp += sizeof(ipfw_dyn_rule);
1596                         }
1597                 }
1598                 IPFW_BUCK_UNLOCK(i);
1599         }
1600
1601         if (last != NULL) /* mark last dynamic rule */
1602                 bzero(&last->next, sizeof(last));
1603         *pbp = bp;
1604 }
1605 /* end of file */