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>
50 #include <sys/socket.h>
51 #include <sys/sysctl.h>
52 #include <sys/syslog.h>
53 #include <net/ethernet.h> /* for ETHERTYPE_IP */
55 #include <net/if_var.h>
58 #include <netinet/in.h>
59 #include <netinet/ip.h>
60 #include <netinet/ip_var.h> /* ip_defttl */
61 #include <netinet/ip_fw.h>
62 #include <netinet/tcp_var.h>
63 #include <netinet/udp.h>
65 #include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
67 #include <netinet6/in6_var.h>
68 #include <netinet6/ip6_var.h>
71 #include <netpfil/ipfw/ip_fw_private.h>
73 #include <machine/in_cksum.h> /* XXX for in_cksum */
76 #include <security/mac/mac_framework.h>
80 * Description of dynamic rules.
82 * Dynamic rules are stored in lists accessed through a hash table
83 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
84 * be modified through the sysctl variable dyn_buckets which is
85 * updated when the table becomes empty.
87 * XXX currently there is only one list, ipfw_dyn.
89 * When a packet is received, its address fields are first masked
90 * with the mask defined for the rule, then hashed, then matched
91 * against the entries in the corresponding list.
92 * Dynamic rules can be used for different purposes:
94 * + enforcing limits on the number of sessions;
95 * + in-kernel NAT (not implemented yet)
97 * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
98 * measured in seconds and depending on the flags.
100 * The total number of dynamic rules is equal to UMA zone items count.
101 * The max number of dynamic rules is dyn_max. When we reach
102 * the maximum number of rules we do not create anymore. This is
103 * done to avoid consuming too much memory, but also too much
104 * time when searching on each packet (ideally, we should try instead
105 * to put a limit on the length of the list on each bucket...).
107 * Each dynamic rule holds a pointer to the parent ipfw rule so
108 * we know what action to perform. Dynamic rules are removed when
109 * the parent rule is deleted. XXX we should make them survive.
111 * There are some limitations with dynamic rules -- we do not
112 * obey the 'randomized match', and we do not do multiple
113 * passes through the firewall. XXX check the latter!!!
116 struct ipfw_dyn_bucket {
117 struct mtx mtx; /* Bucket protecting lock */
118 ipfw_dyn_rule *head; /* Pointer to first rule */
122 * Static variables followed by global ones
124 static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v);
125 static VNET_DEFINE(u_int32_t, dyn_buckets_max);
126 static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
127 static VNET_DEFINE(struct callout, ipfw_timeout);
128 #define V_ipfw_dyn_v VNET(ipfw_dyn_v)
129 #define V_dyn_buckets_max VNET(dyn_buckets_max)
130 #define V_curr_dyn_buckets VNET(curr_dyn_buckets)
131 #define V_ipfw_timeout VNET(ipfw_timeout)
133 static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone);
134 #define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone)
136 #define IPFW_BUCK_LOCK_INIT(b) \
137 mtx_init(&(b)->mtx, "IPFW dynamic bucket", NULL, MTX_DEF)
138 #define IPFW_BUCK_LOCK_DESTROY(b) \
139 mtx_destroy(&(b)->mtx)
140 #define IPFW_BUCK_LOCK(i) mtx_lock(&V_ipfw_dyn_v[(i)].mtx)
141 #define IPFW_BUCK_UNLOCK(i) mtx_unlock(&V_ipfw_dyn_v[(i)].mtx)
142 #define IPFW_BUCK_ASSERT(i) mtx_assert(&V_ipfw_dyn_v[(i)].mtx, MA_OWNED)
145 * Timeouts for various events in handing dynamic rules.
147 static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
148 static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
149 static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
150 static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
151 static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
152 static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
154 #define V_dyn_ack_lifetime VNET(dyn_ack_lifetime)
155 #define V_dyn_syn_lifetime VNET(dyn_syn_lifetime)
156 #define V_dyn_fin_lifetime VNET(dyn_fin_lifetime)
157 #define V_dyn_rst_lifetime VNET(dyn_rst_lifetime)
158 #define V_dyn_udp_lifetime VNET(dyn_udp_lifetime)
159 #define V_dyn_short_lifetime VNET(dyn_short_lifetime)
162 * Keepalives are sent if dyn_keepalive is set. They are sent every
163 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
164 * seconds of lifetime of a rule.
165 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
166 * than dyn_keepalive_period.
169 static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
170 static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
171 static VNET_DEFINE(u_int32_t, dyn_keepalive);
172 static VNET_DEFINE(time_t, dyn_keepalive_last);
174 #define V_dyn_keepalive_interval VNET(dyn_keepalive_interval)
175 #define V_dyn_keepalive_period VNET(dyn_keepalive_period)
176 #define V_dyn_keepalive VNET(dyn_keepalive)
177 #define V_dyn_keepalive_last VNET(dyn_keepalive_last)
179 static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
181 #define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone)
182 #define V_dyn_max VNET(dyn_max)
184 /* for userspace, we emulate the uma_zone_counter with ipfw_dyn_count */
185 static int ipfw_dyn_count; /* number of objects */
187 #ifdef USERSPACE /* emulation of UMA object counters for userspace */
188 #define uma_zone_get_cur(x) ipfw_dyn_count
189 #endif /* USERSPACE */
191 static int last_log; /* Log ratelimiting */
193 static void ipfw_dyn_tick(void *vnetx);
194 static void check_dyn_rules(struct ip_fw_chain *, struct ip_fw *,
198 static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS);
199 static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS);
203 SYSCTL_DECL(_net_inet_ip_fw);
204 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
205 CTLFLAG_RW, &VNET_NAME(dyn_buckets_max), 0,
206 "Max number of dyn. buckets");
207 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets,
208 CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0,
209 "Current Number of dyn. buckets");
210 SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_count,
211 CTLTYPE_UINT|CTLFLAG_RD, 0, 0, sysctl_ipfw_dyn_count, "IU",
212 "Number of dyn. rules");
213 SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_max,
214 CTLTYPE_UINT|CTLFLAG_RW, 0, 0, sysctl_ipfw_dyn_max, "IU",
215 "Max number of dyn. rules");
216 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime,
217 CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0,
218 "Lifetime of dyn. rules for acks");
219 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime,
220 CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0,
221 "Lifetime of dyn. rules for syn");
222 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime,
223 CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0,
224 "Lifetime of dyn. rules for fin");
225 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime,
226 CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0,
227 "Lifetime of dyn. rules for rst");
228 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime,
229 CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0,
230 "Lifetime of dyn. rules for UDP");
231 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime,
232 CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0,
233 "Lifetime of dyn. rules for other situations");
234 SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
235 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
236 "Enable keepalives for dyn. rules");
240 #endif /* SYSCTL_NODE */
244 hash_packet6(struct ipfw_flow_id *id)
247 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
248 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
249 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
250 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
251 (id->dst_port) ^ (id->src_port);
256 * IMPORTANT: the hash function for dynamic rules must be commutative
257 * in source and destination (ip,port), because rules are bidirectional
258 * and we want to find both in the same bucket.
261 hash_packet(struct ipfw_flow_id *id, int buckets)
266 if (IS_IP6_FLOW_ID(id))
267 i = hash_packet6(id);
270 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
276 * Print customizable flow id description via log(9) facility.
279 print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
280 char *prefix, char *postfix)
284 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
286 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
290 if (IS_IP6_FLOW_ID(id)) {
291 ip6_sprintf(src, &id->src_ip6);
292 ip6_sprintf(dst, &id->dst_ip6);
296 da.s_addr = htonl(id->src_ip);
297 inet_ntop(AF_INET, &da, src, sizeof(src));
298 da.s_addr = htonl(id->dst_ip);
299 inet_ntop(AF_INET, &da, dst, sizeof(dst));
301 log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
302 prefix, dyn_type, src, id->src_port, dst,
303 id->dst_port, DYN_COUNT, postfix);
306 #define print_dyn_rule(id, dtype, prefix, postfix) \
307 print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
309 #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
312 * Lookup a dynamic rule, locked version.
314 static ipfw_dyn_rule *
315 lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
319 * Stateful ipfw extensions.
320 * Lookup into dynamic session queue.
322 #define MATCH_REVERSE 0
323 #define MATCH_FORWARD 1
325 #define MATCH_UNKNOWN 3
326 int dir = MATCH_NONE;
327 ipfw_dyn_rule *prev, *q = NULL;
331 for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
332 if (q->dyn_type == O_LIMIT_PARENT && q->count)
335 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
338 if (IS_IP6_FLOW_ID(pkt)) {
339 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
340 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
341 pkt->src_port == q->id.src_port &&
342 pkt->dst_port == q->id.dst_port) {
346 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
347 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
348 pkt->src_port == q->id.dst_port &&
349 pkt->dst_port == q->id.src_port) {
354 if (pkt->src_ip == q->id.src_ip &&
355 pkt->dst_ip == q->id.dst_ip &&
356 pkt->src_port == q->id.src_port &&
357 pkt->dst_port == q->id.dst_port) {
361 if (pkt->src_ip == q->id.dst_ip &&
362 pkt->dst_ip == q->id.src_ip &&
363 pkt->src_port == q->id.dst_port &&
364 pkt->dst_port == q->id.src_port) {
371 goto done; /* q = NULL, not found */
373 if (prev != NULL) { /* found and not in front */
374 prev->next = q->next;
375 q->next = V_ipfw_dyn_v[i].head;
376 V_ipfw_dyn_v[i].head = q;
378 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
380 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
382 #define BOTH_SYN (TH_SYN | (TH_SYN << 8))
383 #define BOTH_FIN (TH_FIN | (TH_FIN << 8))
384 #define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8))
385 #define ACK_FWD 0x10000 /* fwd ack seen */
386 #define ACK_REV 0x20000 /* rev ack seen */
388 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
389 switch (q->state & TCP_FLAGS) {
390 case TH_SYN: /* opening */
391 q->expire = time_uptime + V_dyn_syn_lifetime;
394 case BOTH_SYN: /* move to established */
395 case BOTH_SYN | TH_FIN: /* one side tries to close */
396 case BOTH_SYN | (TH_FIN << 8):
397 #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
401 ack = ntohl(tcp->th_ack);
402 if (dir == MATCH_FORWARD) {
403 if (q->ack_fwd == 0 ||
404 _SEQ_GE(ack, q->ack_fwd)) {
409 if (q->ack_rev == 0 ||
410 _SEQ_GE(ack, q->ack_rev)) {
415 if ((q->state & (ACK_FWD | ACK_REV)) ==
416 (ACK_FWD | ACK_REV)) {
417 q->expire = time_uptime + V_dyn_ack_lifetime;
418 q->state &= ~(ACK_FWD | ACK_REV);
422 case BOTH_SYN | BOTH_FIN: /* both sides closed */
423 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
424 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
425 q->expire = time_uptime + V_dyn_fin_lifetime;
431 * reset or some invalid combination, but can also
432 * occur if we use keep-state the wrong way.
434 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
435 printf("invalid state: 0x%x\n", q->state);
437 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
438 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
439 q->expire = time_uptime + V_dyn_rst_lifetime;
442 } else if (pkt->proto == IPPROTO_UDP) {
443 q->expire = time_uptime + V_dyn_udp_lifetime;
445 /* other protocols */
446 q->expire = time_uptime + V_dyn_short_lifetime;
449 if (match_direction != NULL)
450 *match_direction = dir;
455 ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
461 i = hash_packet(pkt, V_curr_dyn_buckets);
464 q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp);
467 /* NB: return table locked when q is not NULL */
473 * @p - pointer to dynamic rule
476 ipfw_dyn_unlock(ipfw_dyn_rule *q)
479 IPFW_BUCK_UNLOCK(q->bucket);
483 resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
485 int i, k, nbuckets_old;
487 struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
489 /* Check if given number is power of 2 and less than 64k */
490 if ((nbuckets > 65536) || (!powerof2(nbuckets)))
493 CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
494 V_curr_dyn_buckets, nbuckets);
496 /* Allocate and initialize new hash */
497 dyn_v = malloc(nbuckets * sizeof(ipfw_dyn_rule), M_IPFW,
500 for (i = 0 ; i < nbuckets; i++)
501 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
504 * Call upper half lock, as get_map() do to ease
505 * read-only access to dynamic rules hash from sysctl
507 IPFW_UH_WLOCK(chain);
510 * Acquire chain write lock to permit hash access
511 * for main traffic path without additional locks
515 /* Save old values */
516 nbuckets_old = V_curr_dyn_buckets;
517 dyn_v_old = V_ipfw_dyn_v;
519 /* Skip relinking if array is not set up */
520 if (V_ipfw_dyn_v == NULL)
521 V_curr_dyn_buckets = 0;
523 /* Re-link all dynamic states */
524 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
525 while (V_ipfw_dyn_v[i].head != NULL) {
526 /* Remove from current chain */
527 q = V_ipfw_dyn_v[i].head;
528 V_ipfw_dyn_v[i].head = q->next;
530 /* Get new hash value */
531 k = hash_packet(&q->id, nbuckets);
533 /* Add to the new head */
534 q->next = dyn_v[k].head;
539 /* Update current pointers/buckets values */
540 V_curr_dyn_buckets = nbuckets;
541 V_ipfw_dyn_v = dyn_v;
545 IPFW_UH_WUNLOCK(chain);
547 /* Start periodic callout on initial creation */
548 if (dyn_v_old == NULL) {
549 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
553 /* Destroy all mutexes */
554 for (i = 0 ; i < nbuckets_old ; i++)
555 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
558 free(dyn_v_old, M_IPFW);
564 * Install state of type 'type' for a dynamic session.
565 * The hash table contains two type of rules:
566 * - regular rules (O_KEEP_STATE)
567 * - rules for sessions with limited number of sess per user
568 * (O_LIMIT). When they are created, the parent is
569 * increased by 1, and decreased on delete. In this case,
570 * the third parameter is the parent rule and not the chain.
571 * - "parent" rules for the above (O_LIMIT_PARENT).
573 static ipfw_dyn_rule *
574 add_dyn_rule(struct ipfw_flow_id *id, int i, u_int8_t dyn_type, struct ip_fw *rule)
580 r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
582 if (last_log != time_uptime) {
583 last_log = time_uptime;
584 log(LOG_DEBUG, "ipfw: %s: Cannot allocate rule\n",
592 * refcount on parent is already incremented, so
593 * it is safe to use parent unlocked.
595 if (dyn_type == O_LIMIT) {
596 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
597 if ( parent->dyn_type != O_LIMIT_PARENT)
598 panic("invalid parent");
604 r->expire = time_uptime + V_dyn_syn_lifetime;
606 r->dyn_type = dyn_type;
607 IPFW_ZERO_DYN_COUNTER(r);
611 r->next = V_ipfw_dyn_v[i].head;
612 V_ipfw_dyn_v[i].head = r;
613 DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
618 * lookup dynamic parent rule using pkt and rule as search keys.
619 * If the lookup fails, then install one.
621 static ipfw_dyn_rule *
622 lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule)
627 is_v6 = IS_IP6_FLOW_ID(pkt);
628 i = hash_packet( pkt, V_curr_dyn_buckets );
631 for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
632 if (q->dyn_type == O_LIMIT_PARENT &&
634 pkt->proto == q->id.proto &&
635 pkt->src_port == q->id.src_port &&
636 pkt->dst_port == q->id.dst_port &&
639 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
641 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
642 &(q->id.dst_ip6))) ||
644 pkt->src_ip == q->id.src_ip &&
645 pkt->dst_ip == q->id.dst_ip)
648 q->expire = time_uptime + V_dyn_short_lifetime;
649 DEB(print_dyn_rule(pkt, q->dyn_type,
650 "lookup_dyn_parent found", "");)
654 /* Add virtual limiting rule */
655 return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule);
659 * Install dynamic state for rule type cmd->o.opcode
661 * Returns 1 (failure) if state is not installed because of errors or because
662 * session limitations are enforced.
665 ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
666 struct ip_fw_args *args, uint32_t tablearg)
671 DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");)
673 i = hash_packet(&args->f_id, V_curr_dyn_buckets);
677 q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
679 if (q != NULL) { /* should never occur */
681 if (last_log != time_uptime) {
682 last_log = time_uptime;
683 printf("ipfw: %s: entry already present, done\n",
691 * State limiting is done via uma(9) zone limiting.
692 * Save pointer to newly-installed rule and reject
693 * packet if add_dyn_rule() returned NULL.
694 * Note q is currently set to NULL.
697 switch (cmd->o.opcode) {
698 case O_KEEP_STATE: /* bidir rule */
699 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
702 case O_LIMIT: { /* limit number of sessions */
703 struct ipfw_flow_id id;
704 ipfw_dyn_rule *parent;
706 uint16_t limit_mask = cmd->limit_mask;
709 conn_limit = IP_FW_ARG_TABLEARG(cmd->conn_limit);
712 if (cmd->conn_limit == IP_FW_TABLEARG)
713 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
714 "(tablearg)\n", __func__, conn_limit);
716 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
717 __func__, conn_limit);
720 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
721 id.proto = args->f_id.proto;
722 id.addr_type = args->f_id.addr_type;
723 id.fib = M_GETFIB(args->m);
725 if (IS_IP6_FLOW_ID (&(args->f_id))) {
726 if (limit_mask & DYN_SRC_ADDR)
727 id.src_ip6 = args->f_id.src_ip6;
728 if (limit_mask & DYN_DST_ADDR)
729 id.dst_ip6 = args->f_id.dst_ip6;
731 if (limit_mask & DYN_SRC_ADDR)
732 id.src_ip = args->f_id.src_ip;
733 if (limit_mask & DYN_DST_ADDR)
734 id.dst_ip = args->f_id.dst_ip;
736 if (limit_mask & DYN_SRC_PORT)
737 id.src_port = args->f_id.src_port;
738 if (limit_mask & DYN_DST_PORT)
739 id.dst_port = args->f_id.dst_port;
742 * We have to release lock for previous bucket to
743 * avoid possible deadlock
747 if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) {
748 printf("ipfw: %s: add parent failed\n", __func__);
749 IPFW_BUCK_UNLOCK(pindex);
753 if (parent->count >= conn_limit) {
754 if (V_fw_verbose && last_log != time_uptime) {
755 last_log = time_uptime;
757 last_log = time_uptime;
758 snprintf(sbuf, sizeof(sbuf),
760 parent->rule->rulenum);
761 print_dyn_rule_flags(&args->f_id,
763 LOG_SECURITY | LOG_DEBUG,
764 sbuf, "too many entries");
766 IPFW_BUCK_UNLOCK(pindex);
769 /* Increment counter on parent */
771 IPFW_BUCK_UNLOCK(pindex);
774 q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent);
776 /* Decrement index and notify caller */
778 IPFW_BUCK_LOCK(pindex);
780 IPFW_BUCK_UNLOCK(pindex);
786 printf("ipfw: %s: unknown dynamic rule type %u\n",
787 __func__, cmd->o.opcode);
792 return (1); /* Notify caller about failure */
795 /* XXX just set lifetime */
796 lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
803 * Generate a TCP packet, containing either a RST or a keepalive.
804 * When flags & TH_RST, we are sending a RST packet, because of a
805 * "reset" action matched the packet.
806 * Otherwise we are sending a keepalive, and flags & TH_
807 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
808 * so that MAC can label the reply appropriately.
811 ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
812 u_int32_t ack, int flags)
814 struct mbuf *m = NULL; /* stupid compiler */
816 struct ip *h = NULL; /* stupid compiler */
818 struct ip6_hdr *h6 = NULL;
820 struct tcphdr *th = NULL;
822 MGETHDR(m, M_NOWAIT, MT_DATA);
826 M_SETFIB(m, id->fib);
829 mac_netinet_firewall_reply(replyto, m);
831 mac_netinet_firewall_send(m);
833 (void)replyto; /* don't warn about unused arg */
836 switch (id->addr_type) {
838 len = sizeof(struct ip) + sizeof(struct tcphdr);
842 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
850 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
852 m->m_data += max_linkhdr;
853 m->m_flags |= M_SKIP_FIREWALL;
854 m->m_pkthdr.len = m->m_len = len;
855 m->m_pkthdr.rcvif = NULL;
856 bzero(m->m_data, len);
858 switch (id->addr_type) {
860 h = mtod(m, struct ip *);
862 /* prepare for checksum */
863 h->ip_p = IPPROTO_TCP;
864 h->ip_len = htons(sizeof(struct tcphdr));
866 h->ip_src.s_addr = htonl(id->src_ip);
867 h->ip_dst.s_addr = htonl(id->dst_ip);
869 h->ip_src.s_addr = htonl(id->dst_ip);
870 h->ip_dst.s_addr = htonl(id->src_ip);
873 th = (struct tcphdr *)(h + 1);
877 h6 = mtod(m, struct ip6_hdr *);
879 /* prepare for checksum */
880 h6->ip6_nxt = IPPROTO_TCP;
881 h6->ip6_plen = htons(sizeof(struct tcphdr));
883 h6->ip6_src = id->src_ip6;
884 h6->ip6_dst = id->dst_ip6;
886 h6->ip6_src = id->dst_ip6;
887 h6->ip6_dst = id->src_ip6;
890 th = (struct tcphdr *)(h6 + 1);
896 th->th_sport = htons(id->src_port);
897 th->th_dport = htons(id->dst_port);
899 th->th_sport = htons(id->dst_port);
900 th->th_dport = htons(id->src_port);
902 th->th_off = sizeof(struct tcphdr) >> 2;
904 if (flags & TH_RST) {
905 if (flags & TH_ACK) {
906 th->th_seq = htonl(ack);
907 th->th_flags = TH_RST;
911 th->th_ack = htonl(seq);
912 th->th_flags = TH_RST | TH_ACK;
916 * Keepalive - use caller provided sequence numbers
918 th->th_seq = htonl(seq);
919 th->th_ack = htonl(ack);
920 th->th_flags = TH_ACK;
923 switch (id->addr_type) {
925 th->th_sum = in_cksum(m, len);
927 /* finish the ip header */
929 h->ip_hl = sizeof(*h) >> 2;
930 h->ip_tos = IPTOS_LOWDELAY;
931 h->ip_off = htons(0);
932 h->ip_len = htons(len);
933 h->ip_ttl = V_ip_defttl;
938 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
939 sizeof(struct tcphdr));
941 /* finish the ip6 header */
942 h6->ip6_vfc |= IPV6_VERSION;
943 h6->ip6_hlim = IPV6_DEFHLIM;
952 * Queue keepalive packets for given dynamic rule
954 static struct mbuf **
955 ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
957 struct mbuf *m_rev, *m_fwd;
959 m_rev = (q->state & ACK_REV) ? NULL :
960 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
961 m_fwd = (q->state & ACK_FWD) ? NULL :
962 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
966 mtailp = &(*mtailp)->m_nextpkt;
970 mtailp = &(*mtailp)->m_nextpkt;
977 * This procedure is used to perform various maintance
978 * on dynamic hash list. Currently it is called every second.
981 ipfw_dyn_tick(void * vnetx)
983 struct ip_fw_chain *chain;
986 struct vnet *vp = vnetx;
991 chain = &V_layer3_chain;
993 /* Run keepalive checks every keepalive_period iff ka is enabled */
994 if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
995 (V_dyn_keepalive != 0)) {
996 V_dyn_keepalive_last = time_uptime;
1000 check_dyn_rules(chain, NULL, RESVD_SET, check_ka, 1);
1002 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
1009 * Walk thru all dynamic states doing generic maintance:
1010 * 1) free expired states
1011 * 2) free all states based on deleted rule / set
1012 * 3) send keepalives for states if needed
1014 * @chain - pointer to current ipfw rules chain
1015 * @rule - delete all states originated by given rule if != NULL
1016 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1017 * @check_ka - perform checking/sending keepalives
1018 * @timer - indicate call from timer routine.
1020 * Timer routine must call this function unlocked to permit
1021 * sending keepalives/resizing table.
1023 * Others has to call function with IPFW_UH_WLOCK held.
1024 * Additionally, function assume that dynamic rule/set is
1025 * ALREADY deleted so no new states can be generated by
1028 * Write lock is needed to ensure that unused parent rules
1029 * are not freed by other instance (see stage 2, 3)
1032 check_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule,
1033 int set, int check_ka, int timer)
1035 struct mbuf *m0, *m, *mnext, **mtailp;
1037 int i, dyn_count, new_buckets = 0, max_buckets;
1038 int expired = 0, expired_limits = 0, parents = 0, total = 0;
1039 ipfw_dyn_rule *q, *q_prev, *q_next;
1040 ipfw_dyn_rule *exp_head, **exptailp;
1041 ipfw_dyn_rule *exp_lhead, **expltailp;
1043 KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1046 /* Avoid possible LOR */
1047 KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1051 * Do not perform any checks if we currently have no dynamic states
1056 /* Expired states */
1058 exptailp = &exp_head;
1060 /* Expired limit states */
1062 expltailp = &exp_lhead;
1065 * We make a chain of packets to go out here -- not deferring
1066 * until after we drop the IPFW dynamic rule lock would result
1067 * in a lock order reversal with the normal packet input -> ipfw
1073 /* Protect from hash resizing */
1075 IPFW_UH_WLOCK(chain);
1077 IPFW_UH_WLOCK_ASSERT(chain);
1079 #define NEXT_RULE() { q_prev = q; q = q->next ; continue; }
1081 /* Stage 1: perform requested deletion */
1082 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1084 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1085 /* account every rule */
1088 /* Skip parent rules at all */
1089 if (q->dyn_type == O_LIMIT_PARENT) {
1095 * Remove rules which are:
1097 * 2) created by given rule
1098 * 3) created by any rule in given set
1100 if ((TIME_LEQ(q->expire, time_uptime)) ||
1101 ((rule != NULL) && (q->rule == rule)) ||
1102 ((set != RESVD_SET) && (q->rule->set == set))) {
1103 /* Unlink q from current list */
1105 if (q == V_ipfw_dyn_v[i].head)
1106 V_ipfw_dyn_v[i].head = q_next;
1108 q_prev->next = q_next;
1112 /* queue q to expire list */
1113 if (q->dyn_type != O_LIMIT) {
1115 exptailp = &(*exptailp)->next;
1116 DEB(print_dyn_rule(&q->id, q->dyn_type,
1117 "unlink entry", "left");
1120 /* Separate list for limit rules */
1122 expltailp = &(*expltailp)->next;
1124 DEB(print_dyn_rule(&q->id, q->dyn_type,
1125 "unlink limit entry", "left");
1135 * Check if we need to send keepalive:
1136 * we need to ensure if is time to do KA,
1137 * this is established TCP session, and
1138 * expire time is within keepalive interval
1140 if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1141 ((q->state & BOTH_SYN) == BOTH_SYN) &&
1142 (TIME_LEQ(q->expire, time_uptime +
1143 V_dyn_keepalive_interval)))
1144 mtailp = ipfw_dyn_send_ka(mtailp, q);
1148 IPFW_BUCK_UNLOCK(i);
1151 /* Stage 2: decrement counters from O_LIMIT parents */
1152 if (expired_limits != 0) {
1154 * XXX: Note that deleting set with more than one
1155 * heavily-used LIMIT rules can result in overwhelming
1156 * locking due to lack of per-hash value sorting
1158 * We should probably think about:
1159 * 1) pre-allocating hash of size, say,
1160 * MAX(16, V_curr_dyn_buckets / 1024)
1161 * 2) checking if expired_limits is large enough
1162 * 3) If yes, init hash (or its part), re-link
1163 * current list and start decrementing procedure in
1164 * each bucket separately
1168 * Small optimization: do not unlock bucket until
1169 * we see the next item resides in different bucket
1171 if (exp_lhead != NULL) {
1172 i = exp_lhead->parent->bucket;
1175 for (q = exp_lhead; q != NULL; q = q->next) {
1176 if (i != q->parent->bucket) {
1177 IPFW_BUCK_UNLOCK(i);
1178 i = q->parent->bucket;
1182 /* Decrease parent refcount */
1185 if (exp_lhead != NULL)
1186 IPFW_BUCK_UNLOCK(i);
1190 * We protectet ourselves from unused parent deletion
1191 * (from the timer function) by holding UH write lock.
1194 /* Stage 3: remove unused parent rules */
1195 if ((parents != 0) && (expired != 0)) {
1196 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1198 for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1199 if (q->dyn_type != O_LIMIT_PARENT)
1205 /* Parent rule without consumers */
1207 /* Unlink q from current list */
1209 if (q == V_ipfw_dyn_v[i].head)
1210 V_ipfw_dyn_v[i].head = q_next;
1212 q_prev->next = q_next;
1216 /* Add to expired list */
1218 exptailp = &(*exptailp)->next;
1220 DEB(print_dyn_rule(&q->id, q->dyn_type,
1221 "unlink parent entry", "left");
1228 IPFW_BUCK_UNLOCK(i);
1236 * Check if we need to resize hash:
1237 * if current number of states exceeds number of buckes in hash,
1238 * grow hash size to the minimum power of 2 which is bigger than
1239 * current states count. Limit hash size by 64k.
1241 max_buckets = (V_dyn_buckets_max > 65536) ?
1242 65536 : V_dyn_buckets_max;
1244 dyn_count = DYN_COUNT;
1246 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1247 (dyn_count < max_buckets)) {
1248 new_buckets = V_curr_dyn_buckets;
1249 while (new_buckets < dyn_count) {
1252 if (new_buckets >= max_buckets)
1257 IPFW_UH_WUNLOCK(chain);
1260 /* Finally delete old states ad limits if any */
1261 for (q = exp_head; q != NULL; q = q_next) {
1263 uma_zfree(V_ipfw_dyn_rule_zone, q);
1267 for (q = exp_lhead; q != NULL; q = q_next) {
1269 uma_zfree(V_ipfw_dyn_rule_zone, q);
1274 * The rest code MUST be called from timer routine only
1275 * without holding any locks
1280 /* Send keepalive packets if any */
1281 for (m = m0; m != NULL; m = mnext) {
1282 mnext = m->m_nextpkt;
1283 m->m_nextpkt = NULL;
1284 h = mtod(m, struct ip *);
1286 ip_output(m, NULL, NULL, 0, NULL, NULL);
1289 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1293 /* Run table resize without holding any locks */
1294 if (new_buckets != 0)
1295 resize_dynamic_table(chain, new_buckets);
1299 * Deletes all dynamic rules originated by given rule or all rules in
1300 * given set. Specify RESVD_SET to indicate set should not be used.
1301 * @chain - pointer to current ipfw rules chain
1302 * @rule - delete all states originated by given rule if != NULL
1303 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1305 * Function has to be called with IPFW_UH_WLOCK held.
1306 * Additionally, function assume that dynamic rule/set is
1307 * ALREADY deleted so no new states can be generated by
1311 ipfw_expire_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set)
1314 check_dyn_rules(chain, rule, set, 0, 0);
1318 ipfw_dyn_init(struct ip_fw_chain *chain)
1321 V_ipfw_dyn_v = NULL;
1322 V_dyn_buckets_max = 256; /* must be power of 2 */
1323 V_curr_dyn_buckets = 256; /* must be power of 2 */
1325 V_dyn_ack_lifetime = 300;
1326 V_dyn_syn_lifetime = 20;
1327 V_dyn_fin_lifetime = 1;
1328 V_dyn_rst_lifetime = 1;
1329 V_dyn_udp_lifetime = 10;
1330 V_dyn_short_lifetime = 5;
1332 V_dyn_keepalive_interval = 20;
1333 V_dyn_keepalive_period = 5;
1334 V_dyn_keepalive = 1; /* do send keepalives */
1335 V_dyn_keepalive_last = time_uptime;
1337 V_dyn_max = 4096; /* max # of dynamic rules */
1339 V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1340 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1343 /* Enforce limit on dynamic rules */
1344 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1346 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1349 * This can potentially be done on first dynamic rule
1350 * being added to chain.
1352 resize_dynamic_table(chain, V_curr_dyn_buckets);
1356 ipfw_dyn_uninit(int pass)
1361 callout_drain(&V_ipfw_timeout);
1365 if (V_ipfw_dyn_v != NULL) {
1367 * Skip deleting all dynamic states -
1368 * uma_zdestroy() does this more efficiently;
1371 /* Destroy all mutexes */
1372 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1373 IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1374 free(V_ipfw_dyn_v, M_IPFW);
1375 V_ipfw_dyn_v = NULL;
1378 uma_zdestroy(V_ipfw_dyn_rule_zone);
1383 * Get/set maximum number of dynamic states in given VNET instance.
1386 sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1389 unsigned int nstates;
1391 nstates = V_dyn_max;
1393 error = sysctl_handle_int(oidp, &nstates, 0, req);
1394 /* Read operation or some error */
1395 if ((error != 0) || (req->newptr == NULL))
1398 V_dyn_max = nstates;
1399 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1405 * Get current number of dynamic states in given VNET instance.
1408 sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1411 unsigned int nstates;
1413 nstates = DYN_COUNT;
1415 error = sysctl_handle_int(oidp, &nstates, 0, req);
1422 * Returns number of dynamic rules.
1428 return (V_ipfw_dyn_v == NULL) ? 0 :
1429 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1433 * Fill given buffer with dynamic states.
1434 * IPFW_UH_RLOCK has to be held while calling.
1437 ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1439 ipfw_dyn_rule *p, *last = NULL;
1443 if (V_ipfw_dyn_v == NULL)
1447 IPFW_UH_RLOCK_ASSERT(chain);
1449 for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1451 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1452 if (bp + sizeof *p <= ep) {
1453 ipfw_dyn_rule *dst =
1454 (ipfw_dyn_rule *)bp;
1455 bcopy(p, dst, sizeof *p);
1456 bcopy(&(p->rule->rulenum), &(dst->rule),
1457 sizeof(p->rule->rulenum));
1459 * store set number into high word of
1460 * dst->rule pointer.
1462 bcopy(&(p->rule->set),
1463 (char *)&dst->rule +
1464 sizeof(p->rule->rulenum),
1465 sizeof(p->rule->set));
1467 * store a non-null value in "next".
1468 * The userland code will interpret a
1469 * NULL here as a marker
1470 * for the last dynamic rule.
1472 bcopy(&dst, &dst->next, sizeof(dst));
1475 TIME_LEQ(dst->expire, time_uptime) ?
1476 0 : dst->expire - time_uptime ;
1477 bp += sizeof(ipfw_dyn_rule);
1480 IPFW_BUCK_UNLOCK(i);
1483 if (last != NULL) /* mark last dynamic rule */
1484 bzero(&last->next, sizeof(last));