2 * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
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
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
33 * Dynamic rule support for ipfw
39 #error IPFIREWALL requires INET.
41 #include "opt_inet6.h"
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/malloc.h>
47 #include <sys/kernel.h>
49 #include <sys/socket.h>
50 #include <sys/sysctl.h>
51 #include <sys/syslog.h>
52 #include <net/ethernet.h> /* for ETHERTYPE_IP */
56 #include <netinet/in.h>
57 #include <netinet/ip.h>
58 #include <netinet/ip_var.h> /* ip_defttl */
59 #include <netinet/ip_fw.h>
60 #include <netinet/tcp_var.h>
61 #include <netinet/udp.h>
63 #include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
65 #include <netinet6/in6_var.h>
66 #include <netinet6/ip6_var.h>
69 #include <netpfil/ipfw/ip_fw_private.h>
71 #include <machine/in_cksum.h> /* XXX for in_cksum */
74 #include <security/mac/mac_framework.h>
78 * Description of dynamic rules.
80 * Dynamic rules are stored in lists accessed through a hash table
81 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
82 * be modified through the sysctl variable dyn_buckets which is
83 * updated when the table becomes empty.
85 * XXX currently there is only one list, ipfw_dyn.
87 * When a packet is received, its address fields are first masked
88 * with the mask defined for the rule, then hashed, then matched
89 * against the entries in the corresponding list.
90 * Dynamic rules can be used for different purposes:
92 * + enforcing limits on the number of sessions;
93 * + in-kernel NAT (not implemented yet)
95 * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
96 * measured in seconds and depending on the flags.
98 * The total number of dynamic rules is equal to UMA zone items count.
99 * The max number of dynamic rules is dyn_max. When we reach
100 * the maximum number of rules we do not create anymore. This is
101 * done to avoid consuming too much memory, but also too much
102 * time when searching on each packet (ideally, we should try instead
103 * to put a limit on the length of the list on each bucket...).
105 * Each dynamic rule holds a pointer to the parent ipfw rule so
106 * we know what action to perform. Dynamic rules are removed when
107 * the parent rule is deleted. XXX we should make them survive.
109 * There are some limitations with dynamic rules -- we do not
110 * obey the 'randomized match', and we do not do multiple
111 * passes through the firewall. XXX check the latter!!!
114 struct ipfw_dyn_bucket {
115 struct mtx mtx; /* Bucket protecting lock */
116 ipfw_dyn_rule *head; /* Pointer to first rule */
120 * Static variables followed by global ones
122 static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v);
123 static VNET_DEFINE(u_int32_t, dyn_buckets_max);
124 static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
125 static VNET_DEFINE(struct callout, ipfw_timeout);
126 #define V_ipfw_dyn_v VNET(ipfw_dyn_v)
127 #define V_dyn_buckets_max VNET(dyn_buckets_max)
128 #define V_curr_dyn_buckets VNET(curr_dyn_buckets)
129 #define V_ipfw_timeout VNET(ipfw_timeout)
131 static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone);
132 #define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone)
134 #define IPFW_BUCK_LOCK_INIT(b) \
135 mtx_init(&(b)->mtx, "IPFW dynamic bucket", NULL, MTX_DEF)
136 #define IPFW_BUCK_LOCK_DESTROY(b) \
137 mtx_destroy(&(b)->mtx)
138 #define IPFW_BUCK_LOCK(i) mtx_lock(&V_ipfw_dyn_v[(i)].mtx)
139 #define IPFW_BUCK_UNLOCK(i) mtx_unlock(&V_ipfw_dyn_v[(i)].mtx)
140 #define IPFW_BUCK_ASSERT(i) mtx_assert(&V_ipfw_dyn_v[(i)].mtx, MA_OWNED)
143 * Timeouts for various events in handing dynamic rules.
145 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
146 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
147 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
148 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
149 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
150 static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
152 #define V_dyn_ack_lifetime VNET(dyn_ack_lifetime)
153 #define V_dyn_syn_lifetime VNET(dyn_syn_lifetime)
154 #define V_dyn_fin_lifetime VNET(dyn_fin_lifetime)
155 #define V_dyn_rst_lifetime VNET(dyn_rst_lifetime)
156 #define V_dyn_udp_lifetime VNET(dyn_udp_lifetime)
157 #define V_dyn_short_lifetime VNET(dyn_short_lifetime)
160 * Keepalives are sent if dyn_keepalive is set. They are sent every
161 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
162 * seconds of lifetime of a rule.
163 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
164 * than dyn_keepalive_period.
167 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
168 static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
169 static VNET_DEFINE(u_int32_t, dyn_keepalive);
170 static VNET_DEFINE(time_t, dyn_keepalive_last);
172 #define V_dyn_keepalive_interval VNET(dyn_keepalive_interval)
173 #define V_dyn_keepalive_period VNET(dyn_keepalive_period)
174 #define V_dyn_keepalive VNET(dyn_keepalive)
175 #define V_dyn_keepalive_last VNET(dyn_keepalive_last)
177 static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
179 #define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone)
180 #define V_dyn_max VNET(dyn_max)
182 static int last_log; /* Log ratelimiting */
184 static void ipfw_dyn_tick(void *vnetx);
185 static void check_dyn_rules(struct ip_fw_chain *, struct ip_fw *,
189 static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS);
190 static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS);
194 SYSCTL_DECL(_net_inet_ip_fw);
195 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
196 CTLFLAG_RW, &VNET_NAME(dyn_buckets_max), 0,
197 "Max number of dyn. buckets");
198 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets,
199 CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0,
200 "Current Number of dyn. buckets");
201 SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_count,
202 CTLTYPE_UINT|CTLFLAG_RD, 0, 0, sysctl_ipfw_dyn_count, "IU",
203 "Number of dyn. rules");
204 SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_max,
205 CTLTYPE_UINT|CTLFLAG_RW, 0, 0, sysctl_ipfw_dyn_max, "IU",
206 "Max number of dyn. rules");
207 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime,
208 CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0,
209 "Lifetime of dyn. rules for acks");
210 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime,
211 CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0,
212 "Lifetime of dyn. rules for syn");
213 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime,
214 CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0,
215 "Lifetime of dyn. rules for fin");
216 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime,
217 CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0,
218 "Lifetime of dyn. rules for rst");
219 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime,
220 CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0,
221 "Lifetime of dyn. rules for UDP");
222 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime,
223 CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0,
224 "Lifetime of dyn. rules for other situations");
225 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
226 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
227 "Enable keepalives for dyn. rules");
231 #endif /* SYSCTL_NODE */
235 hash_packet6(struct ipfw_flow_id *id)
238 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
239 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
240 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
241 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
242 (id->dst_port) ^ (id->src_port);
247 * IMPORTANT: the hash function for dynamic rules must be commutative
248 * in source and destination (ip,port), because rules are bidirectional
249 * and we want to find both in the same bucket.
252 hash_packet(struct ipfw_flow_id *id, int buckets)
257 if (IS_IP6_FLOW_ID(id))
258 i = hash_packet6(id);
261 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
267 * Print customizable flow id description via log(9) facility.
270 print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
271 char *prefix, char *postfix)
275 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
277 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
281 if (IS_IP6_FLOW_ID(id)) {
282 ip6_sprintf(src, &id->src_ip6);
283 ip6_sprintf(dst, &id->dst_ip6);
287 da.s_addr = htonl(id->src_ip);
288 inet_ntop(AF_INET, &da, src, sizeof(src));
289 da.s_addr = htonl(id->dst_ip);
290 inet_ntop(AF_INET, &da, dst, sizeof(dst));
292 log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
293 prefix, dyn_type, src, id->src_port, dst,
294 id->dst_port, DYN_COUNT, postfix);
297 #define print_dyn_rule(id, dtype, prefix, postfix) \
298 print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
300 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
303 * Lookup a dynamic rule, locked version.
305 static ipfw_dyn_rule *
306 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
310 * Stateful ipfw extensions.
311 * Lookup into dynamic session queue.
313 #define MATCH_REVERSE 0
314 #define MATCH_FORWARD 1
316 #define MATCH_UNKNOWN 3
317 int dir = MATCH_NONE;
318 ipfw_dyn_rule *prev, *q = NULL;
322 for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
323 if (q->dyn_type == O_LIMIT_PARENT && q->count)
326 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
329 if (IS_IP6_FLOW_ID(pkt)) {
330 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
331 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
332 pkt->src_port == q->id.src_port &&
333 pkt->dst_port == q->id.dst_port) {
337 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
338 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
339 pkt->src_port == q->id.dst_port &&
340 pkt->dst_port == q->id.src_port) {
345 if (pkt->src_ip == q->id.src_ip &&
346 pkt->dst_ip == q->id.dst_ip &&
347 pkt->src_port == q->id.src_port &&
348 pkt->dst_port == q->id.dst_port) {
352 if (pkt->src_ip == q->id.dst_ip &&
353 pkt->dst_ip == q->id.src_ip &&
354 pkt->src_port == q->id.dst_port &&
355 pkt->dst_port == q->id.src_port) {
362 goto done; /* q = NULL, not found */
364 if (prev != NULL) { /* found and not in front */
365 prev->next = q->next;
366 q->next = V_ipfw_dyn_v[i].head;
367 V_ipfw_dyn_v[i].head = q;
369 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
371 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
373 #define BOTH_SYN (TH_SYN | (TH_SYN << 8))
374 #define BOTH_FIN (TH_FIN | (TH_FIN << 8))
375 #define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8))
376 #define ACK_FWD 0x10000 /* fwd ack seen */
377 #define ACK_REV 0x20000 /* rev ack seen */
379 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
380 switch (q->state & TCP_FLAGS) {
381 case TH_SYN: /* opening */
382 q->expire = time_uptime + V_dyn_syn_lifetime;
385 case BOTH_SYN: /* move to established */
386 case BOTH_SYN | TH_FIN: /* one side tries to close */
387 case BOTH_SYN | (TH_FIN << 8):
388 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
392 ack = ntohl(tcp->th_ack);
393 if (dir == MATCH_FORWARD) {
394 if (q->ack_fwd == 0 ||
395 _SEQ_GE(ack, q->ack_fwd)) {
400 if (q->ack_rev == 0 ||
401 _SEQ_GE(ack, q->ack_rev)) {
406 if ((q->state & (ACK_FWD | ACK_REV)) ==
407 (ACK_FWD | ACK_REV)) {
408 q->expire = time_uptime + V_dyn_ack_lifetime;
409 q->state &= ~(ACK_FWD | ACK_REV);
413 case BOTH_SYN | BOTH_FIN: /* both sides closed */
414 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
415 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
416 q->expire = time_uptime + V_dyn_fin_lifetime;
422 * reset or some invalid combination, but can also
423 * occur if we use keep-state the wrong way.
425 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
426 printf("invalid state: 0x%x\n", q->state);
428 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
429 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
430 q->expire = time_uptime + V_dyn_rst_lifetime;
433 } else if (pkt->proto == IPPROTO_UDP) {
434 q->expire = time_uptime + V_dyn_udp_lifetime;
436 /* other protocols */
437 q->expire = time_uptime + V_dyn_short_lifetime;
440 if (match_direction != NULL)
441 *match_direction = dir;
446 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
452 i = hash_packet(pkt, V_curr_dyn_buckets);
455 q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp);
458 /* NB: return table locked when q is not NULL */
464 * @p - pointer to dynamic rule
467 ipfw_dyn_unlock(ipfw_dyn_rule *q)
470 IPFW_BUCK_UNLOCK(q->bucket);
474 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
476 int i, k, nbuckets_old;
478 struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
480 /* Check if given number is power of 2 and less than 64k */
481 if ((nbuckets > 65536) || (!powerof2(nbuckets)))
484 CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
485 V_curr_dyn_buckets, nbuckets);
487 /* Allocate and initialize new hash */
488 dyn_v = malloc(nbuckets * sizeof(ipfw_dyn_rule), M_IPFW,
491 for (i = 0 ; i < nbuckets; i++)
492 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
495 * Call upper half lock, as get_map() do to ease
496 * read-only access to dynamic rules hash from sysctl
498 IPFW_UH_WLOCK(chain);
501 * Acquire chain write lock to permit hash access
502 * for main traffic path without additional locks
506 /* Save old values */
507 nbuckets_old = V_curr_dyn_buckets;
508 dyn_v_old = V_ipfw_dyn_v;
510 /* Skip relinking if array is not set up */
511 if (V_ipfw_dyn_v == NULL)
512 V_curr_dyn_buckets = 0;
514 /* Re-link all dynamic states */
515 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
516 while (V_ipfw_dyn_v[i].head != NULL) {
517 /* Remove from current chain */
518 q = V_ipfw_dyn_v[i].head;
519 V_ipfw_dyn_v[i].head = q->next;
521 /* Get new hash value */
522 k = hash_packet(&q->id, nbuckets);
524 /* Add to the new head */
525 q->next = dyn_v[k].head;
530 /* Update current pointers/buckets values */
531 V_curr_dyn_buckets = nbuckets;
532 V_ipfw_dyn_v = dyn_v;
536 IPFW_UH_WUNLOCK(chain);
538 /* Start periodic callout on initial creation */
539 if (dyn_v_old == NULL) {
540 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
544 /* Destroy all mutexes */
545 for (i = 0 ; i < nbuckets_old ; i++)
546 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
549 free(dyn_v_old, M_IPFW);
555 * Install state of type 'type' for a dynamic session.
556 * The hash table contains two type of rules:
557 * - regular rules (O_KEEP_STATE)
558 * - rules for sessions with limited number of sess per user
559 * (O_LIMIT). When they are created, the parent is
560 * increased by 1, and decreased on delete. In this case,
561 * the third parameter is the parent rule and not the chain.
562 * - "parent" rules for the above (O_LIMIT_PARENT).
564 static ipfw_dyn_rule *
565 add_dyn_rule(struct ipfw_flow_id *id, int i, u_int8_t dyn_type, struct ip_fw *rule)
571 r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
573 if (last_log != time_uptime) {
574 last_log = time_uptime;
575 log(LOG_DEBUG, "ipfw: %s: Cannot allocate rule\n",
582 * refcount on parent is already incremented, so
583 * it is safe to use parent unlocked.
585 if (dyn_type == O_LIMIT) {
586 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
587 if ( parent->dyn_type != O_LIMIT_PARENT)
588 panic("invalid parent");
594 r->expire = time_uptime + V_dyn_syn_lifetime;
596 r->dyn_type = dyn_type;
597 IPFW_ZERO_DYN_COUNTER(r);
601 r->next = V_ipfw_dyn_v[i].head;
602 V_ipfw_dyn_v[i].head = r;
603 DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
608 * lookup dynamic parent rule using pkt and rule as search keys.
609 * If the lookup fails, then install one.
611 static ipfw_dyn_rule *
612 lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule)
617 is_v6 = IS_IP6_FLOW_ID(pkt);
618 i = hash_packet( pkt, V_curr_dyn_buckets );
621 for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
622 if (q->dyn_type == O_LIMIT_PARENT &&
624 pkt->proto == q->id.proto &&
625 pkt->src_port == q->id.src_port &&
626 pkt->dst_port == q->id.dst_port &&
629 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
631 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
632 &(q->id.dst_ip6))) ||
634 pkt->src_ip == q->id.src_ip &&
635 pkt->dst_ip == q->id.dst_ip)
638 q->expire = time_uptime + V_dyn_short_lifetime;
639 DEB(print_dyn_rule(pkt, q->dyn_type,
640 "lookup_dyn_parent found", "");)
644 /* Add virtual limiting rule */
645 return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule);
649 * Install dynamic state for rule type cmd->o.opcode
651 * Returns 1 (failure) if state is not installed because of errors or because
652 * session limitations are enforced.
655 ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
656 struct ip_fw_args *args, uint32_t tablearg)
661 DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");)
663 i = hash_packet(&args->f_id, V_curr_dyn_buckets);
667 q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
669 if (q != NULL) { /* should never occur */
671 if (last_log != time_uptime) {
672 last_log = time_uptime;
673 printf("ipfw: %s: entry already present, done\n",
681 * State limiting is done via uma(9) zone limiting.
682 * Save pointer to newly-installed rule and reject
683 * packet if add_dyn_rule() returned NULL.
684 * Note q is currently set to NULL.
687 switch (cmd->o.opcode) {
688 case O_KEEP_STATE: /* bidir rule */
689 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
692 case O_LIMIT: { /* limit number of sessions */
693 struct ipfw_flow_id id;
694 ipfw_dyn_rule *parent;
696 uint16_t limit_mask = cmd->limit_mask;
699 conn_limit = IP_FW_ARG_TABLEARG(cmd->conn_limit);
702 if (cmd->conn_limit == IP_FW_TABLEARG)
703 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
704 "(tablearg)\n", __func__, conn_limit);
706 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
707 __func__, conn_limit);
710 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
711 id.proto = args->f_id.proto;
712 id.addr_type = args->f_id.addr_type;
713 id.fib = M_GETFIB(args->m);
715 if (IS_IP6_FLOW_ID (&(args->f_id))) {
716 if (limit_mask & DYN_SRC_ADDR)
717 id.src_ip6 = args->f_id.src_ip6;
718 if (limit_mask & DYN_DST_ADDR)
719 id.dst_ip6 = args->f_id.dst_ip6;
721 if (limit_mask & DYN_SRC_ADDR)
722 id.src_ip = args->f_id.src_ip;
723 if (limit_mask & DYN_DST_ADDR)
724 id.dst_ip = args->f_id.dst_ip;
726 if (limit_mask & DYN_SRC_PORT)
727 id.src_port = args->f_id.src_port;
728 if (limit_mask & DYN_DST_PORT)
729 id.dst_port = args->f_id.dst_port;
732 * We have to release lock for previous bucket to
733 * avoid possible deadlock
737 if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) {
738 printf("ipfw: %s: add parent failed\n", __func__);
739 IPFW_BUCK_UNLOCK(pindex);
743 if (parent->count >= conn_limit) {
744 if (V_fw_verbose && last_log != time_uptime) {
745 last_log = time_uptime;
747 last_log = time_uptime;
748 snprintf(sbuf, sizeof(sbuf),
750 parent->rule->rulenum);
751 print_dyn_rule_flags(&args->f_id,
753 LOG_SECURITY | LOG_DEBUG,
754 sbuf, "too many entries");
756 IPFW_BUCK_UNLOCK(pindex);
759 /* Increment counter on parent */
761 IPFW_BUCK_UNLOCK(pindex);
764 q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent);
766 /* Decrement index and notify caller */
768 IPFW_BUCK_LOCK(pindex);
770 IPFW_BUCK_UNLOCK(pindex);
776 printf("ipfw: %s: unknown dynamic rule type %u\n",
777 __func__, cmd->o.opcode);
782 return (1); /* Notify caller about failure */
785 /* XXX just set lifetime */
786 lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
793 * Generate a TCP packet, containing either a RST or a keepalive.
794 * When flags & TH_RST, we are sending a RST packet, because of a
795 * "reset" action matched the packet.
796 * Otherwise we are sending a keepalive, and flags & TH_
797 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
798 * so that MAC can label the reply appropriately.
801 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
802 u_int32_t ack, int flags)
804 struct mbuf *m = NULL; /* stupid compiler */
806 struct ip *h = NULL; /* stupid compiler */
808 struct ip6_hdr *h6 = NULL;
810 struct tcphdr *th = NULL;
812 MGETHDR(m, M_NOWAIT, MT_DATA);
816 M_SETFIB(m, id->fib);
819 mac_netinet_firewall_reply(replyto, m);
821 mac_netinet_firewall_send(m);
823 (void)replyto; /* don't warn about unused arg */
826 switch (id->addr_type) {
828 len = sizeof(struct ip) + sizeof(struct tcphdr);
832 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
840 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
842 m->m_data += max_linkhdr;
843 m->m_flags |= M_SKIP_FIREWALL;
844 m->m_pkthdr.len = m->m_len = len;
845 m->m_pkthdr.rcvif = NULL;
846 bzero(m->m_data, len);
848 switch (id->addr_type) {
850 h = mtod(m, struct ip *);
852 /* prepare for checksum */
853 h->ip_p = IPPROTO_TCP;
854 h->ip_len = htons(sizeof(struct tcphdr));
856 h->ip_src.s_addr = htonl(id->src_ip);
857 h->ip_dst.s_addr = htonl(id->dst_ip);
859 h->ip_src.s_addr = htonl(id->dst_ip);
860 h->ip_dst.s_addr = htonl(id->src_ip);
863 th = (struct tcphdr *)(h + 1);
867 h6 = mtod(m, struct ip6_hdr *);
869 /* prepare for checksum */
870 h6->ip6_nxt = IPPROTO_TCP;
871 h6->ip6_plen = htons(sizeof(struct tcphdr));
873 h6->ip6_src = id->src_ip6;
874 h6->ip6_dst = id->dst_ip6;
876 h6->ip6_src = id->dst_ip6;
877 h6->ip6_dst = id->src_ip6;
880 th = (struct tcphdr *)(h6 + 1);
886 th->th_sport = htons(id->src_port);
887 th->th_dport = htons(id->dst_port);
889 th->th_sport = htons(id->dst_port);
890 th->th_dport = htons(id->src_port);
892 th->th_off = sizeof(struct tcphdr) >> 2;
894 if (flags & TH_RST) {
895 if (flags & TH_ACK) {
896 th->th_seq = htonl(ack);
897 th->th_flags = TH_RST;
901 th->th_ack = htonl(seq);
902 th->th_flags = TH_RST | TH_ACK;
906 * Keepalive - use caller provided sequence numbers
908 th->th_seq = htonl(seq);
909 th->th_ack = htonl(ack);
910 th->th_flags = TH_ACK;
913 switch (id->addr_type) {
915 th->th_sum = in_cksum(m, len);
917 /* finish the ip header */
919 h->ip_hl = sizeof(*h) >> 2;
920 h->ip_tos = IPTOS_LOWDELAY;
921 h->ip_off = htons(0);
922 h->ip_len = htons(len);
923 h->ip_ttl = V_ip_defttl;
928 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
929 sizeof(struct tcphdr));
931 /* finish the ip6 header */
932 h6->ip6_vfc |= IPV6_VERSION;
933 h6->ip6_hlim = IPV6_DEFHLIM;
942 * Queue keepalive packets for given dynamic rule
944 static struct mbuf **
945 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
947 struct mbuf *m_rev, *m_fwd;
949 m_rev = (q->state & ACK_REV) ? NULL :
950 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
951 m_fwd = (q->state & ACK_FWD) ? NULL :
952 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
956 mtailp = &(*mtailp)->m_nextpkt;
960 mtailp = &(*mtailp)->m_nextpkt;
967 * This procedure is used to perform various maintance
968 * on dynamic hash list. Currently it is called every second.
971 ipfw_dyn_tick(void * vnetx)
973 struct ip_fw_chain *chain;
976 struct vnet *vp = vnetx;
981 chain = &V_layer3_chain;
983 /* Run keepalive checks every keepalive_period iff ka is enabled */
984 if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
985 (V_dyn_keepalive != 0)) {
986 V_dyn_keepalive_last = time_uptime;
990 check_dyn_rules(chain, NULL, RESVD_SET, check_ka, 1);
992 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
999 * Walk thru all dynamic states doing generic maintance:
1000 * 1) free expired states
1001 * 2) free all states based on deleted rule / set
1002 * 3) send keepalives for states if needed
1004 * @chain - pointer to current ipfw rules chain
1005 * @rule - delete all states originated by given rule if != NULL
1006 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1007 * @check_ka - perform checking/sending keepalives
1008 * @timer - indicate call from timer routine.
1010 * Timer routine must call this function unlocked to permit
1011 * sending keepalives/resizing table.
1013 * Others has to call function with IPFW_UH_WLOCK held.
1014 * Additionally, function assume that dynamic rule/set is
1015 * ALREADY deleted so no new states can be generated by
1018 * Write lock is needed to ensure that unused parent rules
1019 * are not freed by other instance (see stage 2, 3)
1022 check_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule,
1023 int set, int check_ka, int timer)
1025 struct mbuf *m0, *m, *mnext, **mtailp;
1027 int i, dyn_count, new_buckets = 0, max_buckets;
1028 int expired = 0, expired_limits = 0, parents = 0, total = 0;
1029 ipfw_dyn_rule *q, *q_prev, *q_next;
1030 ipfw_dyn_rule *exp_head, **exptailp;
1031 ipfw_dyn_rule *exp_lhead, **expltailp;
1033 KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1036 /* Avoid possible LOR */
1037 KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1041 * Do not perform any checks if we currently have no dynamic states
1046 /* Expired states */
1048 exptailp = &exp_head;
1050 /* Expired limit states */
1052 expltailp = &exp_lhead;
1055 * We make a chain of packets to go out here -- not deferring
1056 * until after we drop the IPFW dynamic rule lock would result
1057 * in a lock order reversal with the normal packet input -> ipfw
1063 /* Protect from hash resizing */
1065 IPFW_UH_WLOCK(chain);
1067 IPFW_UH_WLOCK_ASSERT(chain);
1069 #define NEXT_RULE() { q_prev = q; q = q->next ; continue; }
1071 /* Stage 1: perform requested deletion */
1072 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1074 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1075 /* account every rule */
1078 /* Skip parent rules at all */
1079 if (q->dyn_type == O_LIMIT_PARENT) {
1085 * Remove rules which are:
1087 * 2) created by given rule
1088 * 3) created by any rule in given set
1090 if ((TIME_LEQ(q->expire, time_uptime)) ||
1091 ((rule != NULL) && (q->rule == rule)) ||
1092 ((set != RESVD_SET) && (q->rule->set == set))) {
1093 /* Unlink q from current list */
1095 if (q == V_ipfw_dyn_v[i].head)
1096 V_ipfw_dyn_v[i].head = q_next;
1098 q_prev->next = q_next;
1102 /* queue q to expire list */
1103 if (q->dyn_type != O_LIMIT) {
1105 exptailp = &(*exptailp)->next;
1106 DEB(print_dyn_rule(&q->id, q->dyn_type,
1107 "unlink entry", "left");
1110 /* Separate list for limit rules */
1112 expltailp = &(*expltailp)->next;
1114 DEB(print_dyn_rule(&q->id, q->dyn_type,
1115 "unlink limit entry", "left");
1125 * Check if we need to send keepalive:
1126 * we need to ensure if is time to do KA,
1127 * this is established TCP session, and
1128 * expire time is within keepalive interval
1130 if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1131 ((q->state & BOTH_SYN) == BOTH_SYN) &&
1132 (TIME_LEQ(q->expire, time_uptime +
1133 V_dyn_keepalive_interval)))
1134 mtailp = ipfw_dyn_send_ka(mtailp, q);
1138 IPFW_BUCK_UNLOCK(i);
1141 /* Stage 2: decrement counters from O_LIMIT parents */
1142 if (expired_limits != 0) {
1144 * XXX: Note that deleting set with more than one
1145 * heavily-used LIMIT rules can result in overwhelming
1146 * locking due to lack of per-hash value sorting
1148 * We should probably think about:
1149 * 1) pre-allocating hash of size, say,
1150 * MAX(16, V_curr_dyn_buckets / 1024)
1151 * 2) checking if expired_limits is large enough
1152 * 3) If yes, init hash (or its part), re-link
1153 * current list and start decrementing procedure in
1154 * each bucket separately
1158 * Small optimization: do not unlock bucket until
1159 * we see the next item resides in different bucket
1161 if (exp_lhead != NULL) {
1162 i = exp_lhead->parent->bucket;
1165 for (q = exp_lhead; q != NULL; q = q->next) {
1166 if (i != q->parent->bucket) {
1167 IPFW_BUCK_UNLOCK(i);
1168 i = q->parent->bucket;
1172 /* Decrease parent refcount */
1175 if (exp_lhead != NULL)
1176 IPFW_BUCK_UNLOCK(i);
1180 * We protectet ourselves from unused parent deletion
1181 * (from the timer function) by holding UH write lock.
1184 /* Stage 3: remove unused parent rules */
1185 if ((parents != 0) && (expired != 0)) {
1186 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1188 for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1189 if (q->dyn_type != O_LIMIT_PARENT)
1195 /* Parent rule without consumers */
1197 /* Unlink q from current list */
1199 if (q == V_ipfw_dyn_v[i].head)
1200 V_ipfw_dyn_v[i].head = q_next;
1202 q_prev->next = q_next;
1206 /* Add to expired list */
1208 exptailp = &(*exptailp)->next;
1210 DEB(print_dyn_rule(&q->id, q->dyn_type,
1211 "unlink parent entry", "left");
1218 IPFW_BUCK_UNLOCK(i);
1226 * Check if we need to resize hash:
1227 * if current number of states exceeds number of buckes in hash,
1228 * grow hash size to the minimum power of 2 which is bigger than
1229 * current states count. Limit hash size by 64k.
1231 max_buckets = (V_dyn_buckets_max > 65536) ?
1232 65536 : V_dyn_buckets_max;
1234 dyn_count = DYN_COUNT;
1236 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1237 (dyn_count < max_buckets)) {
1238 new_buckets = V_curr_dyn_buckets;
1239 while (new_buckets < dyn_count) {
1242 if (new_buckets >= max_buckets)
1247 IPFW_UH_WUNLOCK(chain);
1250 /* Finally delete old states ad limits if any */
1251 for (q = exp_head; q != NULL; q = q_next) {
1253 uma_zfree(V_ipfw_dyn_rule_zone, q);
1256 for (q = exp_lhead; q != NULL; q = q_next) {
1258 uma_zfree(V_ipfw_dyn_rule_zone, q);
1262 * The rest code MUST be called from timer routine only
1263 * without holding any locks
1268 /* Send keepalive packets if any */
1269 for (m = m0; m != NULL; m = mnext) {
1270 mnext = m->m_nextpkt;
1271 m->m_nextpkt = NULL;
1272 h = mtod(m, struct ip *);
1274 ip_output(m, NULL, NULL, 0, NULL, NULL);
1277 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1281 /* Run table resize without holding any locks */
1282 if (new_buckets != 0)
1283 resize_dynamic_table(chain, new_buckets);
1287 * Deletes all dynamic rules originated by given rule or all rules in
1288 * given set. Specify RESVD_SET to indicate set should not be used.
1289 * @chain - pointer to current ipfw rules chain
1290 * @rule - delete all states originated by given rule if != NULL
1291 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1293 * Function has to be called with IPFW_UH_WLOCK held.
1294 * Additionally, function assume that dynamic rule/set is
1295 * ALREADY deleted so no new states can be generated by
1299 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set)
1302 check_dyn_rules(chain, rule, set, 0, 0);
1306 ipfw_dyn_init(struct ip_fw_chain *chain)
1309 V_ipfw_dyn_v = NULL;
1310 V_dyn_buckets_max = 256; /* must be power of 2 */
1311 V_curr_dyn_buckets = 256; /* must be power of 2 */
1313 V_dyn_ack_lifetime = 300;
1314 V_dyn_syn_lifetime = 20;
1315 V_dyn_fin_lifetime = 1;
1316 V_dyn_rst_lifetime = 1;
1317 V_dyn_udp_lifetime = 10;
1318 V_dyn_short_lifetime = 5;
1320 V_dyn_keepalive_interval = 20;
1321 V_dyn_keepalive_period = 5;
1322 V_dyn_keepalive = 1; /* do send keepalives */
1323 V_dyn_keepalive_last = time_uptime;
1325 V_dyn_max = 4096; /* max # of dynamic rules */
1327 V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1328 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1331 /* Enforce limit on dynamic rules */
1332 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1334 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1337 * This can potentially be done on first dynamic rule
1338 * being added to chain.
1340 resize_dynamic_table(chain, V_curr_dyn_buckets);
1344 ipfw_dyn_uninit(int pass)
1349 callout_drain(&V_ipfw_timeout);
1353 if (V_ipfw_dyn_v != NULL) {
1355 * Skip deleting all dynamic states -
1356 * uma_zdestroy() does this more efficiently;
1359 /* Destroy all mutexes */
1360 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1361 IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1362 free(V_ipfw_dyn_v, M_IPFW);
1363 V_ipfw_dyn_v = NULL;
1366 uma_zdestroy(V_ipfw_dyn_rule_zone);
1371 * Get/set maximum number of dynamic states in given VNET instance.
1374 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1377 unsigned int nstates;
1379 nstates = V_dyn_max;
1381 error = sysctl_handle_int(oidp, &nstates, 0, req);
1382 /* Read operation or some error */
1383 if ((error != 0) || (req->newptr == NULL))
1386 V_dyn_max = nstates;
1387 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1393 * Get current number of dynamic states in given VNET instance.
1396 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1399 unsigned int nstates;
1401 nstates = DYN_COUNT;
1403 error = sysctl_handle_int(oidp, &nstates, 0, req);
1410 * Returns number of dynamic rules.
1416 return (V_ipfw_dyn_v == NULL) ? 0 :
1417 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1421 * Fill given buffer with dynamic states.
1422 * IPFW_UH_RLOCK has to be held while calling.
1425 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1427 ipfw_dyn_rule *p, *last = NULL;
1431 if (V_ipfw_dyn_v == NULL)
1435 IPFW_UH_RLOCK_ASSERT(chain);
1437 for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1439 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1440 if (bp + sizeof *p <= ep) {
1441 ipfw_dyn_rule *dst =
1442 (ipfw_dyn_rule *)bp;
1443 bcopy(p, dst, sizeof *p);
1444 bcopy(&(p->rule->rulenum), &(dst->rule),
1445 sizeof(p->rule->rulenum));
1447 * store set number into high word of
1448 * dst->rule pointer.
1450 bcopy(&(p->rule->set),
1451 (char *)&dst->rule +
1452 sizeof(p->rule->rulenum),
1453 sizeof(p->rule->set));
1455 * store a non-null value in "next".
1456 * The userland code will interpret a
1457 * NULL here as a marker
1458 * for the last dynamic rule.
1460 bcopy(&dst, &dst->next, sizeof(dst));
1463 TIME_LEQ(dst->expire, time_uptime) ?
1464 0 : dst->expire - time_uptime ;
1465 bp += sizeof(ipfw_dyn_rule);
1468 IPFW_BUCK_UNLOCK(i);
1471 if (last != NULL) /* mark last dynamic rule */
1472 bzero(&last->next, sizeof(last));