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: stable/10/sys/netpfil/ipfw/ip_fw_dynamic.c 296649 2016-03-11 09:41:46Z ae $");
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/lock.h>
49#include <sys/socket.h>
50#include <sys/sysctl.h>
51#include <sys/syslog.h>
52#include <net/ethernet.h> /* for ETHERTYPE_IP */
53#include <net/if.h>
54#include <net/vnet.h>
55
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>
62
63#include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
64#ifdef INET6
65#include <netinet6/in6_var.h>
66#include <netinet6/ip6_var.h>
67#endif
68
69#include <netpfil/ipfw/ip_fw_private.h>
70
71#include <machine/in_cksum.h> /* XXX for in_cksum */
72
73#ifdef MAC
74#include <security/mac/mac_framework.h>
75#endif
76
77/*
78 * Description of dynamic rules.
79 *
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.
84 *
85 * XXX currently there is only one list, ipfw_dyn.
86 *
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:
91 * + stateful rules;
92 * + enforcing limits on the number of sessions;
93 * + in-kernel NAT (not implemented yet)
94 *
95 * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
96 * measured in seconds and depending on the flags.
97 *
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...).
104 *
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.
108 *
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!!!
112 */
113
114struct ipfw_dyn_bucket {
115 struct mtx mtx; /* Bucket protecting lock */
116 ipfw_dyn_rule *head; /* Pointer to first rule */
117};
118
119/*
120 * Static variables followed by global ones
121 */
122static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v);
123static VNET_DEFINE(u_int32_t, dyn_buckets_max);
124static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
125static 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)
130
131static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone);
132#define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone)
133
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)
141
142/*
143 * Timeouts for various events in handing dynamic rules.
144 */
145static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
146static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
147static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
148static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
149static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
150static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
151
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)
158
159/*
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.
165 */
166
167static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
168static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
169static VNET_DEFINE(u_int32_t, dyn_keepalive);
170static VNET_DEFINE(time_t, dyn_keepalive_last);
171
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)
176
177static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
178
179#define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone)
180#define V_dyn_max VNET(dyn_max)
181
182static int last_log; /* Log ratelimiting */
183
184static void ipfw_dyn_tick(void *vnetx);
185static void check_dyn_rules(struct ip_fw_chain *, struct ip_fw *,
186 int, int, int);
187#ifdef SYSCTL_NODE
188
189static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS);
190static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS);
191
192SYSBEGIN(f2)
193
194SYSCTL_DECL(_net_inet_ip_fw);
195SYSCTL_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");
198SYSCTL_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");
201SYSCTL_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");
204SYSCTL_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");
207SYSCTL_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");
210SYSCTL_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");
213SYSCTL_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");
216SYSCTL_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");
219SYSCTL_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");
222SYSCTL_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");
225SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
226 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
227 "Enable keepalives for dyn. rules");
228
229SYSEND
230
231#endif /* SYSCTL_NODE */
232
233
234#ifdef INET6
235static __inline int
236hash_packet6(struct ipfw_flow_id *id)
237{
238 u_int32_t i;
239 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
240 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
241 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
242 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
243 (id->dst_port) ^ (id->src_port);
244 return i;
245}
246#endif
247
248/*
249 * IMPORTANT: the hash function for dynamic rules must be commutative
250 * in source and destination (ip,port), because rules are bidirectional
251 * and we want to find both in the same bucket.
252 */
253static __inline int
254hash_packet(struct ipfw_flow_id *id, int buckets)
255{
256 u_int32_t i;
257
258#ifdef INET6
259 if (IS_IP6_FLOW_ID(id))
260 i = hash_packet6(id);
261 else
262#endif /* INET6 */
263 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
264 i &= (buckets - 1);
265 return i;
266}
267
268/**
269 * Print customizable flow id description via log(9) facility.
270 */
271static void
272print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
273 char *prefix, char *postfix)
274{
275 struct in_addr da;
276#ifdef INET6
277 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
278#else
279 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
280#endif
281
282#ifdef INET6
283 if (IS_IP6_FLOW_ID(id)) {
284 ip6_sprintf(src, &id->src_ip6);
285 ip6_sprintf(dst, &id->dst_ip6);
286 } else
287#endif
288 {
289 da.s_addr = htonl(id->src_ip);
290 inet_ntop(AF_INET, &da, src, sizeof(src));
291 da.s_addr = htonl(id->dst_ip);
292 inet_ntop(AF_INET, &da, dst, sizeof(dst));
293 }
294 log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
295 prefix, dyn_type, src, id->src_port, dst,
296 id->dst_port, DYN_COUNT, postfix);
297}
298
299#define print_dyn_rule(id, dtype, prefix, postfix) \
300 print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
301
302#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
303
304/*
305 * Lookup a dynamic rule, locked version.
306 */
307static ipfw_dyn_rule *
308lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
309 struct tcphdr *tcp)
310{
311 /*
312 * Stateful ipfw extensions.
313 * Lookup into dynamic session queue.
314 */
315#define MATCH_REVERSE 0
316#define MATCH_FORWARD 1
317#define MATCH_NONE 2
318#define MATCH_UNKNOWN 3
319 int dir = MATCH_NONE;
320 ipfw_dyn_rule *prev, *q = NULL;
321
322 IPFW_BUCK_ASSERT(i);
323
324 for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
325 if (q->dyn_type == O_LIMIT_PARENT && q->count)
326 continue;
327
328 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
329 continue;
330
331 if (IS_IP6_FLOW_ID(pkt)) {
332 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
333 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
334 pkt->src_port == q->id.src_port &&
335 pkt->dst_port == q->id.dst_port) {
336 dir = MATCH_FORWARD;
337 break;
338 }
339 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
340 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
341 pkt->src_port == q->id.dst_port &&
342 pkt->dst_port == q->id.src_port) {
343 dir = MATCH_REVERSE;
344 break;
345 }
346 } else {
347 if (pkt->src_ip == q->id.src_ip &&
348 pkt->dst_ip == q->id.dst_ip &&
349 pkt->src_port == q->id.src_port &&
350 pkt->dst_port == q->id.dst_port) {
351 dir = MATCH_FORWARD;
352 break;
353 }
354 if (pkt->src_ip == q->id.dst_ip &&
355 pkt->dst_ip == q->id.src_ip &&
356 pkt->src_port == q->id.dst_port &&
357 pkt->dst_port == q->id.src_port) {
358 dir = MATCH_REVERSE;
359 break;
360 }
361 }
362 }
363 if (q == NULL)
364 goto done; /* q = NULL, not found */
365
366 if (prev != NULL) { /* found and not in front */
367 prev->next = q->next;
368 q->next = V_ipfw_dyn_v[i].head;
369 V_ipfw_dyn_v[i].head = q;
370 }
371 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
372 uint32_t ack;
373 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
374
375#define BOTH_SYN (TH_SYN | (TH_SYN << 8))
376#define BOTH_FIN (TH_FIN | (TH_FIN << 8))
377#define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8))
378#define ACK_FWD 0x10000 /* fwd ack seen */
379#define ACK_REV 0x20000 /* rev ack seen */
380
381 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
382 switch (q->state & TCP_FLAGS) {
383 case TH_SYN: /* opening */
384 q->expire = time_uptime + V_dyn_syn_lifetime;
385 break;
386
387 case BOTH_SYN: /* move to established */
388 case BOTH_SYN | TH_FIN: /* one side tries to close */
389 case BOTH_SYN | (TH_FIN << 8):
390#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
391 if (tcp == NULL)
392 break;
393
394 ack = ntohl(tcp->th_ack);
395 if (dir == MATCH_FORWARD) {
396 if (q->ack_fwd == 0 ||
397 _SEQ_GE(ack, q->ack_fwd)) {
398 q->ack_fwd = ack;
399 q->state |= ACK_FWD;
400 }
401 } else {
402 if (q->ack_rev == 0 ||
403 _SEQ_GE(ack, q->ack_rev)) {
404 q->ack_rev = ack;
405 q->state |= ACK_REV;
406 }
407 }
408 if ((q->state & (ACK_FWD | ACK_REV)) ==
409 (ACK_FWD | ACK_REV)) {
410 q->expire = time_uptime + V_dyn_ack_lifetime;
411 q->state &= ~(ACK_FWD | ACK_REV);
412 }
413 break;
414
415 case BOTH_SYN | BOTH_FIN: /* both sides closed */
416 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
417 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
418 q->expire = time_uptime + V_dyn_fin_lifetime;
419 break;
420
421 default:
422#if 0
423 /*
424 * reset or some invalid combination, but can also
425 * occur if we use keep-state the wrong way.
426 */
427 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
428 printf("invalid state: 0x%x\n", q->state);
429#endif
430 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
431 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
432 q->expire = time_uptime + V_dyn_rst_lifetime;
433 break;
434 }
435 } else if (pkt->proto == IPPROTO_UDP) {
436 q->expire = time_uptime + V_dyn_udp_lifetime;
437 } else {
438 /* other protocols */
439 q->expire = time_uptime + V_dyn_short_lifetime;
440 }
441done:
442 if (match_direction != NULL)
443 *match_direction = dir;
444 return (q);
445}
446
447ipfw_dyn_rule *
448ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
449 struct tcphdr *tcp)
450{
451 ipfw_dyn_rule *q;
452 int i;
453
454 i = hash_packet(pkt, V_curr_dyn_buckets);
455
456 IPFW_BUCK_LOCK(i);
457 q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp);
458 if (q == NULL)
459 IPFW_BUCK_UNLOCK(i);
460 /* NB: return table locked when q is not NULL */
461 return q;
462}
463
464/*
465 * Unlock bucket mtx
466 * @p - pointer to dynamic rule
467 */
468void
469ipfw_dyn_unlock(ipfw_dyn_rule *q)
470{
471
472 IPFW_BUCK_UNLOCK(q->bucket);
473}
474
475static int
476resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
477{
478 int i, k, nbuckets_old;
479 ipfw_dyn_rule *q;
480 struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
481
482 /* Check if given number is power of 2 and less than 64k */
483 if ((nbuckets > 65536) || (!powerof2(nbuckets)))
484 return 1;
485
486 CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
487 V_curr_dyn_buckets, nbuckets);
488
489 /* Allocate and initialize new hash */
490 dyn_v = malloc(nbuckets * sizeof(*dyn_v), M_IPFW,
491 M_WAITOK | M_ZERO);
492
493 for (i = 0 ; i < nbuckets; i++)
494 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
495
496 /*
497 * Call upper half lock, as get_map() do to ease
498 * read-only access to dynamic rules hash from sysctl
499 */
500 IPFW_UH_WLOCK(chain);
501
502 /*
503 * Acquire chain write lock to permit hash access
504 * for main traffic path without additional locks
505 */
506 IPFW_WLOCK(chain);
507
508 /* Save old values */
509 nbuckets_old = V_curr_dyn_buckets;
510 dyn_v_old = V_ipfw_dyn_v;
511
512 /* Skip relinking if array is not set up */
513 if (V_ipfw_dyn_v == NULL)
514 V_curr_dyn_buckets = 0;
515
516 /* Re-link all dynamic states */
517 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
518 while (V_ipfw_dyn_v[i].head != NULL) {
519 /* Remove from current chain */
520 q = V_ipfw_dyn_v[i].head;
521 V_ipfw_dyn_v[i].head = q->next;
522
523 /* Get new hash value */
524 k = hash_packet(&q->id, nbuckets);
525 q->bucket = k;
526 /* Add to the new head */
527 q->next = dyn_v[k].head;
528 dyn_v[k].head = q;
529 }
530 }
531
532 /* Update current pointers/buckets values */
533 V_curr_dyn_buckets = nbuckets;
534 V_ipfw_dyn_v = dyn_v;
535
536 IPFW_WUNLOCK(chain);
537
538 IPFW_UH_WUNLOCK(chain);
539
540 /* Start periodic callout on initial creation */
541 if (dyn_v_old == NULL) {
542 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
543 return (0);
544 }
545
546 /* Destroy all mutexes */
547 for (i = 0 ; i < nbuckets_old ; i++)
548 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
549
550 /* Free old hash */
551 free(dyn_v_old, M_IPFW);
552
553 return 0;
554}
555
556/**
557 * Install state of type 'type' for a dynamic session.
558 * The hash table contains two type of rules:
559 * - regular rules (O_KEEP_STATE)
560 * - rules for sessions with limited number of sess per user
561 * (O_LIMIT). When they are created, the parent is
562 * increased by 1, and decreased on delete. In this case,
563 * the third parameter is the parent rule and not the chain.
564 * - "parent" rules for the above (O_LIMIT_PARENT).
565 */
566static ipfw_dyn_rule *
567add_dyn_rule(struct ipfw_flow_id *id, int i, u_int8_t dyn_type, struct ip_fw *rule)
568{
569 ipfw_dyn_rule *r;
570
571 IPFW_BUCK_ASSERT(i);
572
573 r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
574 if (r == NULL) {
575 if (last_log != time_uptime) {
576 last_log = time_uptime;
577 log(LOG_DEBUG, "ipfw: %s: Cannot allocate rule\n",
578 __func__);
579 }
580 return NULL;
581 }
582
583 /*
584 * refcount on parent is already incremented, so
585 * it is safe to use parent unlocked.
586 */
587 if (dyn_type == O_LIMIT) {
588 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
589 if ( parent->dyn_type != O_LIMIT_PARENT)
590 panic("invalid parent");
591 r->parent = parent;
592 rule = parent->rule;
593 }
594
595 r->id = *id;
596 r->expire = time_uptime + V_dyn_syn_lifetime;
597 r->rule = rule;
598 r->dyn_type = dyn_type;
599 IPFW_ZERO_DYN_COUNTER(r);
600 r->count = 0;
601
602 r->bucket = i;
603 r->next = V_ipfw_dyn_v[i].head;
604 V_ipfw_dyn_v[i].head = r;
605 DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
606 return r;
607}
608
609/**
610 * lookup dynamic parent rule using pkt and rule as search keys.
611 * If the lookup fails, then install one.
612 */
613static ipfw_dyn_rule *
614lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule)
615{
616 ipfw_dyn_rule *q;
617 int i, is_v6;
618
619 is_v6 = IS_IP6_FLOW_ID(pkt);
620 i = hash_packet( pkt, V_curr_dyn_buckets );
621 *pindex = i;
622 IPFW_BUCK_LOCK(i);
623 for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
624 if (q->dyn_type == O_LIMIT_PARENT &&
625 rule== q->rule &&
626 pkt->proto == q->id.proto &&
627 pkt->src_port == q->id.src_port &&
628 pkt->dst_port == q->id.dst_port &&
629 (
630 (is_v6 &&
631 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
632 &(q->id.src_ip6)) &&
633 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
634 &(q->id.dst_ip6))) ||
635 (!is_v6 &&
636 pkt->src_ip == q->id.src_ip &&
637 pkt->dst_ip == q->id.dst_ip)
638 )
639 ) {
640 q->expire = time_uptime + V_dyn_short_lifetime;
641 DEB(print_dyn_rule(pkt, q->dyn_type,
642 "lookup_dyn_parent found", "");)
643 return q;
644 }
645
646 /* Add virtual limiting rule */
647 return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule);
648}
649
650/**
651 * Install dynamic state for rule type cmd->o.opcode
652 *
653 * Returns 1 (failure) if state is not installed because of errors or because
654 * session limitations are enforced.
655 */
656int
657ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
658 struct ip_fw_args *args, uint32_t tablearg)
659{
660 ipfw_dyn_rule *q;
661 int i;
662
663 DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");)
664
665 i = hash_packet(&args->f_id, V_curr_dyn_buckets);
666
667 IPFW_BUCK_LOCK(i);
668
669 q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
670
671 if (q != NULL) { /* should never occur */
672 DEB(
673 if (last_log != time_uptime) {
674 last_log = time_uptime;
675 printf("ipfw: %s: entry already present, done\n",
676 __func__);
677 })
678 IPFW_BUCK_UNLOCK(i);
679 return (0);
680 }
681
682 /*
683 * State limiting is done via uma(9) zone limiting.
684 * Save pointer to newly-installed rule and reject
685 * packet if add_dyn_rule() returned NULL.
686 * Note q is currently set to NULL.
687 */
688
689 switch (cmd->o.opcode) {
690 case O_KEEP_STATE: /* bidir rule */
691 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
692 break;
693
694 case O_LIMIT: { /* limit number of sessions */
695 struct ipfw_flow_id id;
696 ipfw_dyn_rule *parent;
697 uint32_t conn_limit;
698 uint16_t limit_mask = cmd->limit_mask;
699 int pindex;
700
701 conn_limit = IP_FW_ARG_TABLEARG(cmd->conn_limit);
702
703 DEB(
704 if (cmd->conn_limit == IP_FW_TABLEARG)
705 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
706 "(tablearg)\n", __func__, conn_limit);
707 else
708 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
709 __func__, conn_limit);
710 )
711
712 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
713 id.proto = args->f_id.proto;
714 id.addr_type = args->f_id.addr_type;
715 id.fib = M_GETFIB(args->m);
716
717 if (IS_IP6_FLOW_ID (&(args->f_id))) {
718 bzero(&id.src_ip6, sizeof(id.src_ip6));
719 bzero(&id.dst_ip6, sizeof(id.dst_ip6));
720
721 if (limit_mask & DYN_SRC_ADDR)
722 id.src_ip6 = args->f_id.src_ip6;
723 if (limit_mask & DYN_DST_ADDR)
724 id.dst_ip6 = args->f_id.dst_ip6;
725 } else {
726 if (limit_mask & DYN_SRC_ADDR)
727 id.src_ip = args->f_id.src_ip;
728 if (limit_mask & DYN_DST_ADDR)
729 id.dst_ip = args->f_id.dst_ip;
730 }
731 if (limit_mask & DYN_SRC_PORT)
732 id.src_port = args->f_id.src_port;
733 if (limit_mask & DYN_DST_PORT)
734 id.dst_port = args->f_id.dst_port;
735
736 /*
737 * We have to release lock for previous bucket to
738 * avoid possible deadlock
739 */
740 IPFW_BUCK_UNLOCK(i);
741
742 if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) {
743 printf("ipfw: %s: add parent failed\n", __func__);
744 IPFW_BUCK_UNLOCK(pindex);
745 return (1);
746 }
747
748 if (parent->count >= conn_limit) {
749 if (V_fw_verbose && last_log != time_uptime) {
750 last_log = time_uptime;
751 char sbuf[24];
752 last_log = time_uptime;
753 snprintf(sbuf, sizeof(sbuf),
754 "%d drop session",
755 parent->rule->rulenum);
756 print_dyn_rule_flags(&args->f_id,
757 cmd->o.opcode,
758 LOG_SECURITY | LOG_DEBUG,
759 sbuf, "too many entries");
760 }
761 IPFW_BUCK_UNLOCK(pindex);
762 return (1);
763 }
764 /* Increment counter on parent */
765 parent->count++;
766 IPFW_BUCK_UNLOCK(pindex);
767
768 IPFW_BUCK_LOCK(i);
769 q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent);
770 if (q == NULL) {
771 /* Decrement index and notify caller */
772 IPFW_BUCK_UNLOCK(i);
773 IPFW_BUCK_LOCK(pindex);
774 parent->count--;
775 IPFW_BUCK_UNLOCK(pindex);
776 return (1);
777 }
778 break;
779 }
780 default:
781 printf("ipfw: %s: unknown dynamic rule type %u\n",
782 __func__, cmd->o.opcode);
783 }
784
785 if (q == NULL) {
786 IPFW_BUCK_UNLOCK(i);
787 return (1); /* Notify caller about failure */
788 }
789
790 /* XXX just set lifetime */
791 lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
792
793 IPFW_BUCK_UNLOCK(i);
794 return (0);
795}
796
797/*
798 * Generate a TCP packet, containing either a RST or a keepalive.
799 * When flags & TH_RST, we are sending a RST packet, because of a
800 * "reset" action matched the packet.
801 * Otherwise we are sending a keepalive, and flags & TH_
802 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
803 * so that MAC can label the reply appropriately.
804 */
805struct mbuf *
806ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
807 u_int32_t ack, int flags)
808{
809 struct mbuf *m = NULL; /* stupid compiler */
810 int len, dir;
811 struct ip *h = NULL; /* stupid compiler */
812#ifdef INET6
813 struct ip6_hdr *h6 = NULL;
814#endif
815 struct tcphdr *th = NULL;
816
817 MGETHDR(m, M_NOWAIT, MT_DATA);
818 if (m == NULL)
819 return (NULL);
820
821 M_SETFIB(m, id->fib);
822#ifdef MAC
823 if (replyto != NULL)
824 mac_netinet_firewall_reply(replyto, m);
825 else
826 mac_netinet_firewall_send(m);
827#else
828 (void)replyto; /* don't warn about unused arg */
829#endif
830
831 switch (id->addr_type) {
832 case 4:
833 len = sizeof(struct ip) + sizeof(struct tcphdr);
834 break;
835#ifdef INET6
836 case 6:
837 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
838 break;
839#endif
840 default:
841 /* XXX: log me?!? */
842 FREE_PKT(m);
843 return (NULL);
844 }
845 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
846
847 m->m_data += max_linkhdr;
848 m->m_flags |= M_SKIP_FIREWALL;
849 m->m_pkthdr.len = m->m_len = len;
850 m->m_pkthdr.rcvif = NULL;
851 bzero(m->m_data, len);
852
853 switch (id->addr_type) {
854 case 4:
855 h = mtod(m, struct ip *);
856
857 /* prepare for checksum */
858 h->ip_p = IPPROTO_TCP;
859 h->ip_len = htons(sizeof(struct tcphdr));
860 if (dir) {
861 h->ip_src.s_addr = htonl(id->src_ip);
862 h->ip_dst.s_addr = htonl(id->dst_ip);
863 } else {
864 h->ip_src.s_addr = htonl(id->dst_ip);
865 h->ip_dst.s_addr = htonl(id->src_ip);
866 }
867
868 th = (struct tcphdr *)(h + 1);
869 break;
870#ifdef INET6
871 case 6:
872 h6 = mtod(m, struct ip6_hdr *);
873
874 /* prepare for checksum */
875 h6->ip6_nxt = IPPROTO_TCP;
876 h6->ip6_plen = htons(sizeof(struct tcphdr));
877 if (dir) {
878 h6->ip6_src = id->src_ip6;
879 h6->ip6_dst = id->dst_ip6;
880 } else {
881 h6->ip6_src = id->dst_ip6;
882 h6->ip6_dst = id->src_ip6;
883 }
884
885 th = (struct tcphdr *)(h6 + 1);
886 break;
887#endif
888 }
889
890 if (dir) {
891 th->th_sport = htons(id->src_port);
892 th->th_dport = htons(id->dst_port);
893 } else {
894 th->th_sport = htons(id->dst_port);
895 th->th_dport = htons(id->src_port);
896 }
897 th->th_off = sizeof(struct tcphdr) >> 2;
898
899 if (flags & TH_RST) {
900 if (flags & TH_ACK) {
901 th->th_seq = htonl(ack);
902 th->th_flags = TH_RST;
903 } else {
904 if (flags & TH_SYN)
905 seq++;
906 th->th_ack = htonl(seq);
907 th->th_flags = TH_RST | TH_ACK;
908 }
909 } else {
910 /*
911 * Keepalive - use caller provided sequence numbers
912 */
913 th->th_seq = htonl(seq);
914 th->th_ack = htonl(ack);
915 th->th_flags = TH_ACK;
916 }
917
918 switch (id->addr_type) {
919 case 4:
920 th->th_sum = in_cksum(m, len);
921
922 /* finish the ip header */
923 h->ip_v = 4;
924 h->ip_hl = sizeof(*h) >> 2;
925 h->ip_tos = IPTOS_LOWDELAY;
926 h->ip_off = htons(0);
927 h->ip_len = htons(len);
928 h->ip_ttl = V_ip_defttl;
929 h->ip_sum = 0;
930 break;
931#ifdef INET6
932 case 6:
933 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
934 sizeof(struct tcphdr));
935
936 /* finish the ip6 header */
937 h6->ip6_vfc |= IPV6_VERSION;
938 h6->ip6_hlim = IPV6_DEFHLIM;
939 break;
940#endif
941 }
942
943 return (m);
944}
945
946/*
947 * Queue keepalive packets for given dynamic rule
948 */
949static struct mbuf **
950ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
951{
952 struct mbuf *m_rev, *m_fwd;
953
954 m_rev = (q->state & ACK_REV) ? NULL :
955 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
956 m_fwd = (q->state & ACK_FWD) ? NULL :
957 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
958
959 if (m_rev != NULL) {
960 *mtailp = m_rev;
961 mtailp = &(*mtailp)->m_nextpkt;
962 }
963 if (m_fwd != NULL) {
964 *mtailp = m_fwd;
965 mtailp = &(*mtailp)->m_nextpkt;
966 }
967
968 return (mtailp);
969}
970
971/*
972 * This procedure is used to perform various maintance
973 * on dynamic hash list. Currently it is called every second.
974 */
975static void
976ipfw_dyn_tick(void * vnetx)
977{
978 struct ip_fw_chain *chain;
979 int check_ka = 0;
980#ifdef VIMAGE
981 struct vnet *vp = vnetx;
982#endif
983
984 CURVNET_SET(vp);
985
986 chain = &V_layer3_chain;
987
988 /* Run keepalive checks every keepalive_period iff ka is enabled */
989 if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
990 (V_dyn_keepalive != 0)) {
991 V_dyn_keepalive_last = time_uptime;
992 check_ka = 1;
993 }
994
995 check_dyn_rules(chain, NULL, RESVD_SET, check_ka, 1);
996
997 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
998
999 CURVNET_RESTORE();
1000}
1001
1002
1003/*
1004 * Walk thru all dynamic states doing generic maintance:
1005 * 1) free expired states
1006 * 2) free all states based on deleted rule / set
1007 * 3) send keepalives for states if needed
1008 *
1009 * @chain - pointer to current ipfw rules chain
1010 * @rule - delete all states originated by given rule if != NULL
1011 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1012 * @check_ka - perform checking/sending keepalives
1013 * @timer - indicate call from timer routine.
1014 *
1015 * Timer routine must call this function unlocked to permit
1016 * sending keepalives/resizing table.
1017 *
1018 * Others has to call function with IPFW_UH_WLOCK held.
1019 * Additionally, function assume that dynamic rule/set is
1020 * ALREADY deleted so no new states can be generated by
1021 * 'deleted' rules.
1022 *
1023 * Write lock is needed to ensure that unused parent rules
1024 * are not freed by other instance (see stage 2, 3)
1025 */
1026static void
1027check_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule,
1028 int set, int check_ka, int timer)
1029{
1030 struct mbuf *m0, *m, *mnext, **mtailp;
1031 struct ip *h;
1032 int i, dyn_count, new_buckets = 0, max_buckets;
1033 int expired = 0, expired_limits = 0, parents = 0, total = 0;
1034 ipfw_dyn_rule *q, *q_prev, *q_next;
1035 ipfw_dyn_rule *exp_head, **exptailp;
1036 ipfw_dyn_rule *exp_lhead, **expltailp;
1037
1038 KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1039 __func__));
1040
1041 /* Avoid possible LOR */
1042 KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1043 __func__));
1044
1045 /*
1046 * Do not perform any checks if we currently have no dynamic states
1047 */
1048 if (DYN_COUNT == 0)
1049 return;
1050
1051 /* Expired states */
1052 exp_head = NULL;
1053 exptailp = &exp_head;
1054
1055 /* Expired limit states */
1056 exp_lhead = NULL;
1057 expltailp = &exp_lhead;
1058
1059 /*
1060 * We make a chain of packets to go out here -- not deferring
1061 * until after we drop the IPFW dynamic rule lock would result
1062 * in a lock order reversal with the normal packet input -> ipfw
1063 * call stack.
1064 */
1065 m0 = NULL;
1066 mtailp = &m0;
1067
1068 /* Protect from hash resizing */
1069 if (timer != 0)
1070 IPFW_UH_WLOCK(chain);
1071 else
1072 IPFW_UH_WLOCK_ASSERT(chain);
1073
1074#define NEXT_RULE() { q_prev = q; q = q->next ; continue; }
1075
1076 /* Stage 1: perform requested deletion */
1077 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1078 IPFW_BUCK_LOCK(i);
1079 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1080 /* account every rule */
1081 total++;
1082
1083 /* Skip parent rules at all */
1084 if (q->dyn_type == O_LIMIT_PARENT) {
1085 parents++;
1086 NEXT_RULE();
1087 }
1088
1089 /*
1090 * Remove rules which are:
1091 * 1) expired
1092 * 2) created by given rule
1093 * 3) created by any rule in given set
1094 */
1095 if ((TIME_LEQ(q->expire, time_uptime)) ||
1096 ((rule != NULL) && (q->rule == rule)) ||
1097 ((set != RESVD_SET) && (q->rule->set == set))) {
1098 /* Unlink q from current list */
1099 q_next = q->next;
1100 if (q == V_ipfw_dyn_v[i].head)
1101 V_ipfw_dyn_v[i].head = q_next;
1102 else
1103 q_prev->next = q_next;
1104
1105 q->next = NULL;
1106
1107 /* queue q to expire list */
1108 if (q->dyn_type != O_LIMIT) {
1109 *exptailp = q;
1110 exptailp = &(*exptailp)->next;
1111 DEB(print_dyn_rule(&q->id, q->dyn_type,
1112 "unlink entry", "left");
1113 )
1114 } else {
1115 /* Separate list for limit rules */
1116 *expltailp = q;
1117 expltailp = &(*expltailp)->next;
1118 expired_limits++;
1119 DEB(print_dyn_rule(&q->id, q->dyn_type,
1120 "unlink limit entry", "left");
1121 )
1122 }
1123
1124 q = q_next;
1125 expired++;
1126 continue;
1127 }
1128
1129 /*
1130 * Check if we need to send keepalive:
1131 * we need to ensure if is time to do KA,
1132 * this is established TCP session, and
1133 * expire time is within keepalive interval
1134 */
1135 if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1136 ((q->state & BOTH_SYN) == BOTH_SYN) &&
1137 (TIME_LEQ(q->expire, time_uptime +
1138 V_dyn_keepalive_interval)))
1139 mtailp = ipfw_dyn_send_ka(mtailp, q);
1140
1141 NEXT_RULE();
1142 }
1143 IPFW_BUCK_UNLOCK(i);
1144 }
1145
1146 /* Stage 2: decrement counters from O_LIMIT parents */
1147 if (expired_limits != 0) {
1148 /*
1149 * XXX: Note that deleting set with more than one
1150 * heavily-used LIMIT rules can result in overwhelming
1151 * locking due to lack of per-hash value sorting
1152 *
1153 * We should probably think about:
1154 * 1) pre-allocating hash of size, say,
1155 * MAX(16, V_curr_dyn_buckets / 1024)
1156 * 2) checking if expired_limits is large enough
1157 * 3) If yes, init hash (or its part), re-link
1158 * current list and start decrementing procedure in
1159 * each bucket separately
1160 */
1161
1162 /*
1163 * Small optimization: do not unlock bucket until
1164 * we see the next item resides in different bucket
1165 */
1166 if (exp_lhead != NULL) {
1167 i = exp_lhead->parent->bucket;
1168 IPFW_BUCK_LOCK(i);
1169 }
1170 for (q = exp_lhead; q != NULL; q = q->next) {
1171 if (i != q->parent->bucket) {
1172 IPFW_BUCK_UNLOCK(i);
1173 i = q->parent->bucket;
1174 IPFW_BUCK_LOCK(i);
1175 }
1176
1177 /* Decrease parent refcount */
1178 q->parent->count--;
1179 }
1180 if (exp_lhead != NULL)
1181 IPFW_BUCK_UNLOCK(i);
1182 }
1183
1184 /*
1185 * We protectet ourselves from unused parent deletion
1186 * (from the timer function) by holding UH write lock.
1187 */
1188
1189 /* Stage 3: remove unused parent rules */
1190 if ((parents != 0) && (expired != 0)) {
1191 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1192 IPFW_BUCK_LOCK(i);
1193 for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1194 if (q->dyn_type != O_LIMIT_PARENT)
1195 NEXT_RULE();
1196
1197 if (q->count != 0)
1198 NEXT_RULE();
1199
1200 /* Parent rule without consumers */
1201
1202 /* Unlink q from current list */
1203 q_next = q->next;
1204 if (q == V_ipfw_dyn_v[i].head)
1205 V_ipfw_dyn_v[i].head = q_next;
1206 else
1207 q_prev->next = q_next;
1208
1209 q->next = NULL;
1210
1211 /* Add to expired list */
1212 *exptailp = q;
1213 exptailp = &(*exptailp)->next;
1214
1215 DEB(print_dyn_rule(&q->id, q->dyn_type,
1216 "unlink parent entry", "left");
1217 )
1218
1219 expired++;
1220
1221 q = q_next;
1222 }
1223 IPFW_BUCK_UNLOCK(i);
1224 }
1225 }
1226
1227#undef NEXT_RULE
1228
1229 if (timer != 0) {
1230 /*
1231 * Check if we need to resize hash:
1232 * if current number of states exceeds number of buckes in hash,
1233 * grow hash size to the minimum power of 2 which is bigger than
1234 * current states count. Limit hash size by 64k.
1235 */
1236 max_buckets = (V_dyn_buckets_max > 65536) ?
1237 65536 : V_dyn_buckets_max;
1238
1239 dyn_count = DYN_COUNT;
1240
1241 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1242 (dyn_count < max_buckets)) {
1243 new_buckets = V_curr_dyn_buckets;
1244 while (new_buckets < dyn_count) {
1245 new_buckets *= 2;
1246
1247 if (new_buckets >= max_buckets)
1248 break;
1249 }
1250 }
1251
1252 IPFW_UH_WUNLOCK(chain);
1253 }
1254
1255 /* Finally delete old states ad limits if any */
1256 for (q = exp_head; q != NULL; q = q_next) {
1257 q_next = q->next;
1258 uma_zfree(V_ipfw_dyn_rule_zone, q);
1259 }
1260
1261 for (q = exp_lhead; q != NULL; q = q_next) {
1262 q_next = q->next;
1263 uma_zfree(V_ipfw_dyn_rule_zone, q);
1264 }
1265
1266 /*
1267 * The rest code MUST be called from timer routine only
1268 * without holding any locks
1269 */
1270 if (timer == 0)
1271 return;
1272
1273 /* Send keepalive packets if any */
1274 for (m = m0; m != NULL; m = mnext) {
1275 mnext = m->m_nextpkt;
1276 m->m_nextpkt = NULL;
1277 h = mtod(m, struct ip *);
1278 if (h->ip_v == 4)
1279 ip_output(m, NULL, NULL, 0, NULL, NULL);
1280#ifdef INET6
1281 else
1282 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1283#endif
1284 }
1285
1286 /* Run table resize without holding any locks */
1287 if (new_buckets != 0)
1288 resize_dynamic_table(chain, new_buckets);
1289}
1290
1291/*
1292 * Deletes all dynamic rules originated by given rule or all rules in
1293 * given set. Specify RESVD_SET to indicate set should not be used.
1294 * @chain - pointer to current ipfw rules chain
1295 * @rule - delete all states originated by given rule if != NULL
1296 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1297 *
1298 * Function has to be called with IPFW_UH_WLOCK held.
1299 * Additionally, function assume that dynamic rule/set is
1300 * ALREADY deleted so no new states can be generated by
1301 * 'deleted' rules.
1302 */
1303void
1304ipfw_expire_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set)
1305{
1306
1307 check_dyn_rules(chain, rule, set, 0, 0);
1308}
1309
1310void
1311ipfw_dyn_init(struct ip_fw_chain *chain)
1312{
1313
1314 V_ipfw_dyn_v = NULL;
1315 V_dyn_buckets_max = 256; /* must be power of 2 */
1316 V_curr_dyn_buckets = 256; /* must be power of 2 */
1317
1318 V_dyn_ack_lifetime = 300;
1319 V_dyn_syn_lifetime = 20;
1320 V_dyn_fin_lifetime = 1;
1321 V_dyn_rst_lifetime = 1;
1322 V_dyn_udp_lifetime = 10;
1323 V_dyn_short_lifetime = 5;
1324
1325 V_dyn_keepalive_interval = 20;
1326 V_dyn_keepalive_period = 5;
1327 V_dyn_keepalive = 1; /* do send keepalives */
1328 V_dyn_keepalive_last = time_uptime;
1329
1330 V_dyn_max = 4096; /* max # of dynamic rules */
1331
1332 V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1333 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1334 UMA_ALIGN_PTR, 0);
1335
1336 /* Enforce limit on dynamic rules */
1337 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1338
1339 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1340
1341 /*
1342 * This can potentially be done on first dynamic rule
1343 * being added to chain.
1344 */
1345 resize_dynamic_table(chain, V_curr_dyn_buckets);
1346}
1347
1348void
1349ipfw_dyn_uninit(int pass)
1350{
1351 int i;
1352
1353 if (pass == 0) {
1354 callout_drain(&V_ipfw_timeout);
1355 return;
1356 }
1357
1358 if (V_ipfw_dyn_v != NULL) {
1359 /*
1360 * Skip deleting all dynamic states -
1361 * uma_zdestroy() does this more efficiently;
1362 */
1363
1364 /* Destroy all mutexes */
1365 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1366 IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1367 free(V_ipfw_dyn_v, M_IPFW);
1368 V_ipfw_dyn_v = NULL;
1369 }
1370
1371 uma_zdestroy(V_ipfw_dyn_rule_zone);
1372}
1373
1374#ifdef SYSCTL_NODE
1375/*
1376 * Get/set maximum number of dynamic states in given VNET instance.
1377 */
1378static int
1379sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1380{
1381 int error;
1382 unsigned int nstates;
1383
1384 nstates = V_dyn_max;
1385
1386 error = sysctl_handle_int(oidp, &nstates, 0, req);
1387 /* Read operation or some error */
1388 if ((error != 0) || (req->newptr == NULL))
1389 return (error);
1390
1391 V_dyn_max = nstates;
1392 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1393
1394 return (0);
1395}
1396
1397/*
1398 * Get current number of dynamic states in given VNET instance.
1399 */
1400static int
1401sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1402{
1403 int error;
1404 unsigned int nstates;
1405
1406 nstates = DYN_COUNT;
1407
1408 error = sysctl_handle_int(oidp, &nstates, 0, req);
1409
1410 return (error);
1411}
1412#endif
1413
1414/*
1415 * Returns number of dynamic rules.
1416 */
1417int
1418ipfw_dyn_len(void)
1419{
1420
1421 return (V_ipfw_dyn_v == NULL) ? 0 :
1422 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1423}
1424
1425/*
1426 * Fill given buffer with dynamic states.
1427 * IPFW_UH_RLOCK has to be held while calling.
1428 */
1429void
1430ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1431{
1432 ipfw_dyn_rule *p, *last = NULL;
1433 char *bp;
1434 int i;
1435
1436 if (V_ipfw_dyn_v == NULL)
1437 return;
1438 bp = *pbp;
1439
1440 IPFW_UH_RLOCK_ASSERT(chain);
1441
1442 for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1443 IPFW_BUCK_LOCK(i);
1444 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1445 if (bp + sizeof *p <= ep) {
1446 ipfw_dyn_rule *dst =
1447 (ipfw_dyn_rule *)bp;
1448 bcopy(p, dst, sizeof *p);
1449 bcopy(&(p->rule->rulenum), &(dst->rule),
1450 sizeof(p->rule->rulenum));
1451 /*
1452 * store set number into high word of
1453 * dst->rule pointer.
1454 */
1455 bcopy(&(p->rule->set),
1456 (char *)&dst->rule +
1457 sizeof(p->rule->rulenum),
1458 sizeof(p->rule->set));
1459 /*
1460 * store a non-null value in "next".
1461 * The userland code will interpret a
1462 * NULL here as a marker
1463 * for the last dynamic rule.
1464 */
1465 bcopy(&dst, &dst->next, sizeof(dst));
1466 last = dst;
1467 dst->expire =
1468 TIME_LEQ(dst->expire, time_uptime) ?
1469 0 : dst->expire - time_uptime ;
1470 bp += sizeof(ipfw_dyn_rule);
1471 }
1472 }
1473 IPFW_BUCK_UNLOCK(i);
1474 }
1475
1476 if (last != NULL) /* mark last dynamic rule */
1477 bzero(&last->next, sizeof(last));
1478 *pbp = bp;
1479}
1480/* end of file */
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: stable/10/sys/netpfil/ipfw/ip_fw_dynamic.c 296649 2016-03-11 09:41:46Z ae $");
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/lock.h>
49#include <sys/socket.h>
50#include <sys/sysctl.h>
51#include <sys/syslog.h>
52#include <net/ethernet.h> /* for ETHERTYPE_IP */
53#include <net/if.h>
54#include <net/vnet.h>
55
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>
62
63#include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
64#ifdef INET6
65#include <netinet6/in6_var.h>
66#include <netinet6/ip6_var.h>
67#endif
68
69#include <netpfil/ipfw/ip_fw_private.h>
70
71#include <machine/in_cksum.h> /* XXX for in_cksum */
72
73#ifdef MAC
74#include <security/mac/mac_framework.h>
75#endif
76
77/*
78 * Description of dynamic rules.
79 *
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.
84 *
85 * XXX currently there is only one list, ipfw_dyn.
86 *
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:
91 * + stateful rules;
92 * + enforcing limits on the number of sessions;
93 * + in-kernel NAT (not implemented yet)
94 *
95 * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
96 * measured in seconds and depending on the flags.
97 *
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...).
104 *
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.
108 *
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!!!
112 */
113
114struct ipfw_dyn_bucket {
115 struct mtx mtx; /* Bucket protecting lock */
116 ipfw_dyn_rule *head; /* Pointer to first rule */
117};
118
119/*
120 * Static variables followed by global ones
121 */
122static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v);
123static VNET_DEFINE(u_int32_t, dyn_buckets_max);
124static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
125static 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)
130
131static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone);
132#define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone)
133
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)
141
142/*
143 * Timeouts for various events in handing dynamic rules.
144 */
145static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
146static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
147static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
148static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
149static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
150static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
151
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)
158
159/*
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.
165 */
166
167static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
168static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
169static VNET_DEFINE(u_int32_t, dyn_keepalive);
170static VNET_DEFINE(time_t, dyn_keepalive_last);
171
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)
176
177static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
178
179#define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone)
180#define V_dyn_max VNET(dyn_max)
181
182static int last_log; /* Log ratelimiting */
183
184static void ipfw_dyn_tick(void *vnetx);
185static void check_dyn_rules(struct ip_fw_chain *, struct ip_fw *,
186 int, int, int);
187#ifdef SYSCTL_NODE
188
189static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS);
190static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS);
191
192SYSBEGIN(f2)
193
194SYSCTL_DECL(_net_inet_ip_fw);
195SYSCTL_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");
198SYSCTL_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");
201SYSCTL_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");
204SYSCTL_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");
207SYSCTL_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");
210SYSCTL_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");
213SYSCTL_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");
216SYSCTL_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");
219SYSCTL_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");
222SYSCTL_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");
225SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
226 CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
227 "Enable keepalives for dyn. rules");
228
229SYSEND
230
231#endif /* SYSCTL_NODE */
232
233
234#ifdef INET6
235static __inline int
236hash_packet6(struct ipfw_flow_id *id)
237{
238 u_int32_t i;
239 i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
240 (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
241 (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
242 (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
243 (id->dst_port) ^ (id->src_port);
244 return i;
245}
246#endif
247
248/*
249 * IMPORTANT: the hash function for dynamic rules must be commutative
250 * in source and destination (ip,port), because rules are bidirectional
251 * and we want to find both in the same bucket.
252 */
253static __inline int
254hash_packet(struct ipfw_flow_id *id, int buckets)
255{
256 u_int32_t i;
257
258#ifdef INET6
259 if (IS_IP6_FLOW_ID(id))
260 i = hash_packet6(id);
261 else
262#endif /* INET6 */
263 i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
264 i &= (buckets - 1);
265 return i;
266}
267
268/**
269 * Print customizable flow id description via log(9) facility.
270 */
271static void
272print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags,
273 char *prefix, char *postfix)
274{
275 struct in_addr da;
276#ifdef INET6
277 char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
278#else
279 char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
280#endif
281
282#ifdef INET6
283 if (IS_IP6_FLOW_ID(id)) {
284 ip6_sprintf(src, &id->src_ip6);
285 ip6_sprintf(dst, &id->dst_ip6);
286 } else
287#endif
288 {
289 da.s_addr = htonl(id->src_ip);
290 inet_ntop(AF_INET, &da, src, sizeof(src));
291 da.s_addr = htonl(id->dst_ip);
292 inet_ntop(AF_INET, &da, dst, sizeof(dst));
293 }
294 log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n",
295 prefix, dyn_type, src, id->src_port, dst,
296 id->dst_port, DYN_COUNT, postfix);
297}
298
299#define print_dyn_rule(id, dtype, prefix, postfix) \
300 print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix)
301
302#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
303
304/*
305 * Lookup a dynamic rule, locked version.
306 */
307static ipfw_dyn_rule *
308lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, int *match_direction,
309 struct tcphdr *tcp)
310{
311 /*
312 * Stateful ipfw extensions.
313 * Lookup into dynamic session queue.
314 */
315#define MATCH_REVERSE 0
316#define MATCH_FORWARD 1
317#define MATCH_NONE 2
318#define MATCH_UNKNOWN 3
319 int dir = MATCH_NONE;
320 ipfw_dyn_rule *prev, *q = NULL;
321
322 IPFW_BUCK_ASSERT(i);
323
324 for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) {
325 if (q->dyn_type == O_LIMIT_PARENT && q->count)
326 continue;
327
328 if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
329 continue;
330
331 if (IS_IP6_FLOW_ID(pkt)) {
332 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
333 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
334 pkt->src_port == q->id.src_port &&
335 pkt->dst_port == q->id.dst_port) {
336 dir = MATCH_FORWARD;
337 break;
338 }
339 if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
340 IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
341 pkt->src_port == q->id.dst_port &&
342 pkt->dst_port == q->id.src_port) {
343 dir = MATCH_REVERSE;
344 break;
345 }
346 } else {
347 if (pkt->src_ip == q->id.src_ip &&
348 pkt->dst_ip == q->id.dst_ip &&
349 pkt->src_port == q->id.src_port &&
350 pkt->dst_port == q->id.dst_port) {
351 dir = MATCH_FORWARD;
352 break;
353 }
354 if (pkt->src_ip == q->id.dst_ip &&
355 pkt->dst_ip == q->id.src_ip &&
356 pkt->src_port == q->id.dst_port &&
357 pkt->dst_port == q->id.src_port) {
358 dir = MATCH_REVERSE;
359 break;
360 }
361 }
362 }
363 if (q == NULL)
364 goto done; /* q = NULL, not found */
365
366 if (prev != NULL) { /* found and not in front */
367 prev->next = q->next;
368 q->next = V_ipfw_dyn_v[i].head;
369 V_ipfw_dyn_v[i].head = q;
370 }
371 if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
372 uint32_t ack;
373 u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
374
375#define BOTH_SYN (TH_SYN | (TH_SYN << 8))
376#define BOTH_FIN (TH_FIN | (TH_FIN << 8))
377#define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8))
378#define ACK_FWD 0x10000 /* fwd ack seen */
379#define ACK_REV 0x20000 /* rev ack seen */
380
381 q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
382 switch (q->state & TCP_FLAGS) {
383 case TH_SYN: /* opening */
384 q->expire = time_uptime + V_dyn_syn_lifetime;
385 break;
386
387 case BOTH_SYN: /* move to established */
388 case BOTH_SYN | TH_FIN: /* one side tries to close */
389 case BOTH_SYN | (TH_FIN << 8):
390#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
391 if (tcp == NULL)
392 break;
393
394 ack = ntohl(tcp->th_ack);
395 if (dir == MATCH_FORWARD) {
396 if (q->ack_fwd == 0 ||
397 _SEQ_GE(ack, q->ack_fwd)) {
398 q->ack_fwd = ack;
399 q->state |= ACK_FWD;
400 }
401 } else {
402 if (q->ack_rev == 0 ||
403 _SEQ_GE(ack, q->ack_rev)) {
404 q->ack_rev = ack;
405 q->state |= ACK_REV;
406 }
407 }
408 if ((q->state & (ACK_FWD | ACK_REV)) ==
409 (ACK_FWD | ACK_REV)) {
410 q->expire = time_uptime + V_dyn_ack_lifetime;
411 q->state &= ~(ACK_FWD | ACK_REV);
412 }
413 break;
414
415 case BOTH_SYN | BOTH_FIN: /* both sides closed */
416 if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
417 V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
418 q->expire = time_uptime + V_dyn_fin_lifetime;
419 break;
420
421 default:
422#if 0
423 /*
424 * reset or some invalid combination, but can also
425 * occur if we use keep-state the wrong way.
426 */
427 if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
428 printf("invalid state: 0x%x\n", q->state);
429#endif
430 if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
431 V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
432 q->expire = time_uptime + V_dyn_rst_lifetime;
433 break;
434 }
435 } else if (pkt->proto == IPPROTO_UDP) {
436 q->expire = time_uptime + V_dyn_udp_lifetime;
437 } else {
438 /* other protocols */
439 q->expire = time_uptime + V_dyn_short_lifetime;
440 }
441done:
442 if (match_direction != NULL)
443 *match_direction = dir;
444 return (q);
445}
446
447ipfw_dyn_rule *
448ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
449 struct tcphdr *tcp)
450{
451 ipfw_dyn_rule *q;
452 int i;
453
454 i = hash_packet(pkt, V_curr_dyn_buckets);
455
456 IPFW_BUCK_LOCK(i);
457 q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp);
458 if (q == NULL)
459 IPFW_BUCK_UNLOCK(i);
460 /* NB: return table locked when q is not NULL */
461 return q;
462}
463
464/*
465 * Unlock bucket mtx
466 * @p - pointer to dynamic rule
467 */
468void
469ipfw_dyn_unlock(ipfw_dyn_rule *q)
470{
471
472 IPFW_BUCK_UNLOCK(q->bucket);
473}
474
475static int
476resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets)
477{
478 int i, k, nbuckets_old;
479 ipfw_dyn_rule *q;
480 struct ipfw_dyn_bucket *dyn_v, *dyn_v_old;
481
482 /* Check if given number is power of 2 and less than 64k */
483 if ((nbuckets > 65536) || (!powerof2(nbuckets)))
484 return 1;
485
486 CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__,
487 V_curr_dyn_buckets, nbuckets);
488
489 /* Allocate and initialize new hash */
490 dyn_v = malloc(nbuckets * sizeof(*dyn_v), M_IPFW,
491 M_WAITOK | M_ZERO);
492
493 for (i = 0 ; i < nbuckets; i++)
494 IPFW_BUCK_LOCK_INIT(&dyn_v[i]);
495
496 /*
497 * Call upper half lock, as get_map() do to ease
498 * read-only access to dynamic rules hash from sysctl
499 */
500 IPFW_UH_WLOCK(chain);
501
502 /*
503 * Acquire chain write lock to permit hash access
504 * for main traffic path without additional locks
505 */
506 IPFW_WLOCK(chain);
507
508 /* Save old values */
509 nbuckets_old = V_curr_dyn_buckets;
510 dyn_v_old = V_ipfw_dyn_v;
511
512 /* Skip relinking if array is not set up */
513 if (V_ipfw_dyn_v == NULL)
514 V_curr_dyn_buckets = 0;
515
516 /* Re-link all dynamic states */
517 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
518 while (V_ipfw_dyn_v[i].head != NULL) {
519 /* Remove from current chain */
520 q = V_ipfw_dyn_v[i].head;
521 V_ipfw_dyn_v[i].head = q->next;
522
523 /* Get new hash value */
524 k = hash_packet(&q->id, nbuckets);
525 q->bucket = k;
526 /* Add to the new head */
527 q->next = dyn_v[k].head;
528 dyn_v[k].head = q;
529 }
530 }
531
532 /* Update current pointers/buckets values */
533 V_curr_dyn_buckets = nbuckets;
534 V_ipfw_dyn_v = dyn_v;
535
536 IPFW_WUNLOCK(chain);
537
538 IPFW_UH_WUNLOCK(chain);
539
540 /* Start periodic callout on initial creation */
541 if (dyn_v_old == NULL) {
542 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0);
543 return (0);
544 }
545
546 /* Destroy all mutexes */
547 for (i = 0 ; i < nbuckets_old ; i++)
548 IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]);
549
550 /* Free old hash */
551 free(dyn_v_old, M_IPFW);
552
553 return 0;
554}
555
556/**
557 * Install state of type 'type' for a dynamic session.
558 * The hash table contains two type of rules:
559 * - regular rules (O_KEEP_STATE)
560 * - rules for sessions with limited number of sess per user
561 * (O_LIMIT). When they are created, the parent is
562 * increased by 1, and decreased on delete. In this case,
563 * the third parameter is the parent rule and not the chain.
564 * - "parent" rules for the above (O_LIMIT_PARENT).
565 */
566static ipfw_dyn_rule *
567add_dyn_rule(struct ipfw_flow_id *id, int i, u_int8_t dyn_type, struct ip_fw *rule)
568{
569 ipfw_dyn_rule *r;
570
571 IPFW_BUCK_ASSERT(i);
572
573 r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
574 if (r == NULL) {
575 if (last_log != time_uptime) {
576 last_log = time_uptime;
577 log(LOG_DEBUG, "ipfw: %s: Cannot allocate rule\n",
578 __func__);
579 }
580 return NULL;
581 }
582
583 /*
584 * refcount on parent is already incremented, so
585 * it is safe to use parent unlocked.
586 */
587 if (dyn_type == O_LIMIT) {
588 ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
589 if ( parent->dyn_type != O_LIMIT_PARENT)
590 panic("invalid parent");
591 r->parent = parent;
592 rule = parent->rule;
593 }
594
595 r->id = *id;
596 r->expire = time_uptime + V_dyn_syn_lifetime;
597 r->rule = rule;
598 r->dyn_type = dyn_type;
599 IPFW_ZERO_DYN_COUNTER(r);
600 r->count = 0;
601
602 r->bucket = i;
603 r->next = V_ipfw_dyn_v[i].head;
604 V_ipfw_dyn_v[i].head = r;
605 DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");)
606 return r;
607}
608
609/**
610 * lookup dynamic parent rule using pkt and rule as search keys.
611 * If the lookup fails, then install one.
612 */
613static ipfw_dyn_rule *
614lookup_dyn_parent(struct ipfw_flow_id *pkt, int *pindex, struct ip_fw *rule)
615{
616 ipfw_dyn_rule *q;
617 int i, is_v6;
618
619 is_v6 = IS_IP6_FLOW_ID(pkt);
620 i = hash_packet( pkt, V_curr_dyn_buckets );
621 *pindex = i;
622 IPFW_BUCK_LOCK(i);
623 for (q = V_ipfw_dyn_v[i].head ; q != NULL ; q=q->next)
624 if (q->dyn_type == O_LIMIT_PARENT &&
625 rule== q->rule &&
626 pkt->proto == q->id.proto &&
627 pkt->src_port == q->id.src_port &&
628 pkt->dst_port == q->id.dst_port &&
629 (
630 (is_v6 &&
631 IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
632 &(q->id.src_ip6)) &&
633 IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
634 &(q->id.dst_ip6))) ||
635 (!is_v6 &&
636 pkt->src_ip == q->id.src_ip &&
637 pkt->dst_ip == q->id.dst_ip)
638 )
639 ) {
640 q->expire = time_uptime + V_dyn_short_lifetime;
641 DEB(print_dyn_rule(pkt, q->dyn_type,
642 "lookup_dyn_parent found", "");)
643 return q;
644 }
645
646 /* Add virtual limiting rule */
647 return add_dyn_rule(pkt, i, O_LIMIT_PARENT, rule);
648}
649
650/**
651 * Install dynamic state for rule type cmd->o.opcode
652 *
653 * Returns 1 (failure) if state is not installed because of errors or because
654 * session limitations are enforced.
655 */
656int
657ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
658 struct ip_fw_args *args, uint32_t tablearg)
659{
660 ipfw_dyn_rule *q;
661 int i;
662
663 DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");)
664
665 i = hash_packet(&args->f_id, V_curr_dyn_buckets);
666
667 IPFW_BUCK_LOCK(i);
668
669 q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
670
671 if (q != NULL) { /* should never occur */
672 DEB(
673 if (last_log != time_uptime) {
674 last_log = time_uptime;
675 printf("ipfw: %s: entry already present, done\n",
676 __func__);
677 })
678 IPFW_BUCK_UNLOCK(i);
679 return (0);
680 }
681
682 /*
683 * State limiting is done via uma(9) zone limiting.
684 * Save pointer to newly-installed rule and reject
685 * packet if add_dyn_rule() returned NULL.
686 * Note q is currently set to NULL.
687 */
688
689 switch (cmd->o.opcode) {
690 case O_KEEP_STATE: /* bidir rule */
691 q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
692 break;
693
694 case O_LIMIT: { /* limit number of sessions */
695 struct ipfw_flow_id id;
696 ipfw_dyn_rule *parent;
697 uint32_t conn_limit;
698 uint16_t limit_mask = cmd->limit_mask;
699 int pindex;
700
701 conn_limit = IP_FW_ARG_TABLEARG(cmd->conn_limit);
702
703 DEB(
704 if (cmd->conn_limit == IP_FW_TABLEARG)
705 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
706 "(tablearg)\n", __func__, conn_limit);
707 else
708 printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
709 __func__, conn_limit);
710 )
711
712 id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
713 id.proto = args->f_id.proto;
714 id.addr_type = args->f_id.addr_type;
715 id.fib = M_GETFIB(args->m);
716
717 if (IS_IP6_FLOW_ID (&(args->f_id))) {
718 bzero(&id.src_ip6, sizeof(id.src_ip6));
719 bzero(&id.dst_ip6, sizeof(id.dst_ip6));
720
721 if (limit_mask & DYN_SRC_ADDR)
722 id.src_ip6 = args->f_id.src_ip6;
723 if (limit_mask & DYN_DST_ADDR)
724 id.dst_ip6 = args->f_id.dst_ip6;
725 } else {
726 if (limit_mask & DYN_SRC_ADDR)
727 id.src_ip = args->f_id.src_ip;
728 if (limit_mask & DYN_DST_ADDR)
729 id.dst_ip = args->f_id.dst_ip;
730 }
731 if (limit_mask & DYN_SRC_PORT)
732 id.src_port = args->f_id.src_port;
733 if (limit_mask & DYN_DST_PORT)
734 id.dst_port = args->f_id.dst_port;
735
736 /*
737 * We have to release lock for previous bucket to
738 * avoid possible deadlock
739 */
740 IPFW_BUCK_UNLOCK(i);
741
742 if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) {
743 printf("ipfw: %s: add parent failed\n", __func__);
744 IPFW_BUCK_UNLOCK(pindex);
745 return (1);
746 }
747
748 if (parent->count >= conn_limit) {
749 if (V_fw_verbose && last_log != time_uptime) {
750 last_log = time_uptime;
751 char sbuf[24];
752 last_log = time_uptime;
753 snprintf(sbuf, sizeof(sbuf),
754 "%d drop session",
755 parent->rule->rulenum);
756 print_dyn_rule_flags(&args->f_id,
757 cmd->o.opcode,
758 LOG_SECURITY | LOG_DEBUG,
759 sbuf, "too many entries");
760 }
761 IPFW_BUCK_UNLOCK(pindex);
762 return (1);
763 }
764 /* Increment counter on parent */
765 parent->count++;
766 IPFW_BUCK_UNLOCK(pindex);
767
768 IPFW_BUCK_LOCK(i);
769 q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent);
770 if (q == NULL) {
771 /* Decrement index and notify caller */
772 IPFW_BUCK_UNLOCK(i);
773 IPFW_BUCK_LOCK(pindex);
774 parent->count--;
775 IPFW_BUCK_UNLOCK(pindex);
776 return (1);
777 }
778 break;
779 }
780 default:
781 printf("ipfw: %s: unknown dynamic rule type %u\n",
782 __func__, cmd->o.opcode);
783 }
784
785 if (q == NULL) {
786 IPFW_BUCK_UNLOCK(i);
787 return (1); /* Notify caller about failure */
788 }
789
790 /* XXX just set lifetime */
791 lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL);
792
793 IPFW_BUCK_UNLOCK(i);
794 return (0);
795}
796
797/*
798 * Generate a TCP packet, containing either a RST or a keepalive.
799 * When flags & TH_RST, we are sending a RST packet, because of a
800 * "reset" action matched the packet.
801 * Otherwise we are sending a keepalive, and flags & TH_
802 * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
803 * so that MAC can label the reply appropriately.
804 */
805struct mbuf *
806ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
807 u_int32_t ack, int flags)
808{
809 struct mbuf *m = NULL; /* stupid compiler */
810 int len, dir;
811 struct ip *h = NULL; /* stupid compiler */
812#ifdef INET6
813 struct ip6_hdr *h6 = NULL;
814#endif
815 struct tcphdr *th = NULL;
816
817 MGETHDR(m, M_NOWAIT, MT_DATA);
818 if (m == NULL)
819 return (NULL);
820
821 M_SETFIB(m, id->fib);
822#ifdef MAC
823 if (replyto != NULL)
824 mac_netinet_firewall_reply(replyto, m);
825 else
826 mac_netinet_firewall_send(m);
827#else
828 (void)replyto; /* don't warn about unused arg */
829#endif
830
831 switch (id->addr_type) {
832 case 4:
833 len = sizeof(struct ip) + sizeof(struct tcphdr);
834 break;
835#ifdef INET6
836 case 6:
837 len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
838 break;
839#endif
840 default:
841 /* XXX: log me?!? */
842 FREE_PKT(m);
843 return (NULL);
844 }
845 dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
846
847 m->m_data += max_linkhdr;
848 m->m_flags |= M_SKIP_FIREWALL;
849 m->m_pkthdr.len = m->m_len = len;
850 m->m_pkthdr.rcvif = NULL;
851 bzero(m->m_data, len);
852
853 switch (id->addr_type) {
854 case 4:
855 h = mtod(m, struct ip *);
856
857 /* prepare for checksum */
858 h->ip_p = IPPROTO_TCP;
859 h->ip_len = htons(sizeof(struct tcphdr));
860 if (dir) {
861 h->ip_src.s_addr = htonl(id->src_ip);
862 h->ip_dst.s_addr = htonl(id->dst_ip);
863 } else {
864 h->ip_src.s_addr = htonl(id->dst_ip);
865 h->ip_dst.s_addr = htonl(id->src_ip);
866 }
867
868 th = (struct tcphdr *)(h + 1);
869 break;
870#ifdef INET6
871 case 6:
872 h6 = mtod(m, struct ip6_hdr *);
873
874 /* prepare for checksum */
875 h6->ip6_nxt = IPPROTO_TCP;
876 h6->ip6_plen = htons(sizeof(struct tcphdr));
877 if (dir) {
878 h6->ip6_src = id->src_ip6;
879 h6->ip6_dst = id->dst_ip6;
880 } else {
881 h6->ip6_src = id->dst_ip6;
882 h6->ip6_dst = id->src_ip6;
883 }
884
885 th = (struct tcphdr *)(h6 + 1);
886 break;
887#endif
888 }
889
890 if (dir) {
891 th->th_sport = htons(id->src_port);
892 th->th_dport = htons(id->dst_port);
893 } else {
894 th->th_sport = htons(id->dst_port);
895 th->th_dport = htons(id->src_port);
896 }
897 th->th_off = sizeof(struct tcphdr) >> 2;
898
899 if (flags & TH_RST) {
900 if (flags & TH_ACK) {
901 th->th_seq = htonl(ack);
902 th->th_flags = TH_RST;
903 } else {
904 if (flags & TH_SYN)
905 seq++;
906 th->th_ack = htonl(seq);
907 th->th_flags = TH_RST | TH_ACK;
908 }
909 } else {
910 /*
911 * Keepalive - use caller provided sequence numbers
912 */
913 th->th_seq = htonl(seq);
914 th->th_ack = htonl(ack);
915 th->th_flags = TH_ACK;
916 }
917
918 switch (id->addr_type) {
919 case 4:
920 th->th_sum = in_cksum(m, len);
921
922 /* finish the ip header */
923 h->ip_v = 4;
924 h->ip_hl = sizeof(*h) >> 2;
925 h->ip_tos = IPTOS_LOWDELAY;
926 h->ip_off = htons(0);
927 h->ip_len = htons(len);
928 h->ip_ttl = V_ip_defttl;
929 h->ip_sum = 0;
930 break;
931#ifdef INET6
932 case 6:
933 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
934 sizeof(struct tcphdr));
935
936 /* finish the ip6 header */
937 h6->ip6_vfc |= IPV6_VERSION;
938 h6->ip6_hlim = IPV6_DEFHLIM;
939 break;
940#endif
941 }
942
943 return (m);
944}
945
946/*
947 * Queue keepalive packets for given dynamic rule
948 */
949static struct mbuf **
950ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q)
951{
952 struct mbuf *m_rev, *m_fwd;
953
954 m_rev = (q->state & ACK_REV) ? NULL :
955 ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
956 m_fwd = (q->state & ACK_FWD) ? NULL :
957 ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0);
958
959 if (m_rev != NULL) {
960 *mtailp = m_rev;
961 mtailp = &(*mtailp)->m_nextpkt;
962 }
963 if (m_fwd != NULL) {
964 *mtailp = m_fwd;
965 mtailp = &(*mtailp)->m_nextpkt;
966 }
967
968 return (mtailp);
969}
970
971/*
972 * This procedure is used to perform various maintance
973 * on dynamic hash list. Currently it is called every second.
974 */
975static void
976ipfw_dyn_tick(void * vnetx)
977{
978 struct ip_fw_chain *chain;
979 int check_ka = 0;
980#ifdef VIMAGE
981 struct vnet *vp = vnetx;
982#endif
983
984 CURVNET_SET(vp);
985
986 chain = &V_layer3_chain;
987
988 /* Run keepalive checks every keepalive_period iff ka is enabled */
989 if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) &&
990 (V_dyn_keepalive != 0)) {
991 V_dyn_keepalive_last = time_uptime;
992 check_ka = 1;
993 }
994
995 check_dyn_rules(chain, NULL, RESVD_SET, check_ka, 1);
996
997 callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0);
998
999 CURVNET_RESTORE();
1000}
1001
1002
1003/*
1004 * Walk thru all dynamic states doing generic maintance:
1005 * 1) free expired states
1006 * 2) free all states based on deleted rule / set
1007 * 3) send keepalives for states if needed
1008 *
1009 * @chain - pointer to current ipfw rules chain
1010 * @rule - delete all states originated by given rule if != NULL
1011 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1012 * @check_ka - perform checking/sending keepalives
1013 * @timer - indicate call from timer routine.
1014 *
1015 * Timer routine must call this function unlocked to permit
1016 * sending keepalives/resizing table.
1017 *
1018 * Others has to call function with IPFW_UH_WLOCK held.
1019 * Additionally, function assume that dynamic rule/set is
1020 * ALREADY deleted so no new states can be generated by
1021 * 'deleted' rules.
1022 *
1023 * Write lock is needed to ensure that unused parent rules
1024 * are not freed by other instance (see stage 2, 3)
1025 */
1026static void
1027check_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule,
1028 int set, int check_ka, int timer)
1029{
1030 struct mbuf *m0, *m, *mnext, **mtailp;
1031 struct ip *h;
1032 int i, dyn_count, new_buckets = 0, max_buckets;
1033 int expired = 0, expired_limits = 0, parents = 0, total = 0;
1034 ipfw_dyn_rule *q, *q_prev, *q_next;
1035 ipfw_dyn_rule *exp_head, **exptailp;
1036 ipfw_dyn_rule *exp_lhead, **expltailp;
1037
1038 KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated",
1039 __func__));
1040
1041 /* Avoid possible LOR */
1042 KASSERT(!check_ka || timer, ("%s: keepalive check with lock held",
1043 __func__));
1044
1045 /*
1046 * Do not perform any checks if we currently have no dynamic states
1047 */
1048 if (DYN_COUNT == 0)
1049 return;
1050
1051 /* Expired states */
1052 exp_head = NULL;
1053 exptailp = &exp_head;
1054
1055 /* Expired limit states */
1056 exp_lhead = NULL;
1057 expltailp = &exp_lhead;
1058
1059 /*
1060 * We make a chain of packets to go out here -- not deferring
1061 * until after we drop the IPFW dynamic rule lock would result
1062 * in a lock order reversal with the normal packet input -> ipfw
1063 * call stack.
1064 */
1065 m0 = NULL;
1066 mtailp = &m0;
1067
1068 /* Protect from hash resizing */
1069 if (timer != 0)
1070 IPFW_UH_WLOCK(chain);
1071 else
1072 IPFW_UH_WLOCK_ASSERT(chain);
1073
1074#define NEXT_RULE() { q_prev = q; q = q->next ; continue; }
1075
1076 /* Stage 1: perform requested deletion */
1077 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1078 IPFW_BUCK_LOCK(i);
1079 for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) {
1080 /* account every rule */
1081 total++;
1082
1083 /* Skip parent rules at all */
1084 if (q->dyn_type == O_LIMIT_PARENT) {
1085 parents++;
1086 NEXT_RULE();
1087 }
1088
1089 /*
1090 * Remove rules which are:
1091 * 1) expired
1092 * 2) created by given rule
1093 * 3) created by any rule in given set
1094 */
1095 if ((TIME_LEQ(q->expire, time_uptime)) ||
1096 ((rule != NULL) && (q->rule == rule)) ||
1097 ((set != RESVD_SET) && (q->rule->set == set))) {
1098 /* Unlink q from current list */
1099 q_next = q->next;
1100 if (q == V_ipfw_dyn_v[i].head)
1101 V_ipfw_dyn_v[i].head = q_next;
1102 else
1103 q_prev->next = q_next;
1104
1105 q->next = NULL;
1106
1107 /* queue q to expire list */
1108 if (q->dyn_type != O_LIMIT) {
1109 *exptailp = q;
1110 exptailp = &(*exptailp)->next;
1111 DEB(print_dyn_rule(&q->id, q->dyn_type,
1112 "unlink entry", "left");
1113 )
1114 } else {
1115 /* Separate list for limit rules */
1116 *expltailp = q;
1117 expltailp = &(*expltailp)->next;
1118 expired_limits++;
1119 DEB(print_dyn_rule(&q->id, q->dyn_type,
1120 "unlink limit entry", "left");
1121 )
1122 }
1123
1124 q = q_next;
1125 expired++;
1126 continue;
1127 }
1128
1129 /*
1130 * Check if we need to send keepalive:
1131 * we need to ensure if is time to do KA,
1132 * this is established TCP session, and
1133 * expire time is within keepalive interval
1134 */
1135 if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) &&
1136 ((q->state & BOTH_SYN) == BOTH_SYN) &&
1137 (TIME_LEQ(q->expire, time_uptime +
1138 V_dyn_keepalive_interval)))
1139 mtailp = ipfw_dyn_send_ka(mtailp, q);
1140
1141 NEXT_RULE();
1142 }
1143 IPFW_BUCK_UNLOCK(i);
1144 }
1145
1146 /* Stage 2: decrement counters from O_LIMIT parents */
1147 if (expired_limits != 0) {
1148 /*
1149 * XXX: Note that deleting set with more than one
1150 * heavily-used LIMIT rules can result in overwhelming
1151 * locking due to lack of per-hash value sorting
1152 *
1153 * We should probably think about:
1154 * 1) pre-allocating hash of size, say,
1155 * MAX(16, V_curr_dyn_buckets / 1024)
1156 * 2) checking if expired_limits is large enough
1157 * 3) If yes, init hash (or its part), re-link
1158 * current list and start decrementing procedure in
1159 * each bucket separately
1160 */
1161
1162 /*
1163 * Small optimization: do not unlock bucket until
1164 * we see the next item resides in different bucket
1165 */
1166 if (exp_lhead != NULL) {
1167 i = exp_lhead->parent->bucket;
1168 IPFW_BUCK_LOCK(i);
1169 }
1170 for (q = exp_lhead; q != NULL; q = q->next) {
1171 if (i != q->parent->bucket) {
1172 IPFW_BUCK_UNLOCK(i);
1173 i = q->parent->bucket;
1174 IPFW_BUCK_LOCK(i);
1175 }
1176
1177 /* Decrease parent refcount */
1178 q->parent->count--;
1179 }
1180 if (exp_lhead != NULL)
1181 IPFW_BUCK_UNLOCK(i);
1182 }
1183
1184 /*
1185 * We protectet ourselves from unused parent deletion
1186 * (from the timer function) by holding UH write lock.
1187 */
1188
1189 /* Stage 3: remove unused parent rules */
1190 if ((parents != 0) && (expired != 0)) {
1191 for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
1192 IPFW_BUCK_LOCK(i);
1193 for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) {
1194 if (q->dyn_type != O_LIMIT_PARENT)
1195 NEXT_RULE();
1196
1197 if (q->count != 0)
1198 NEXT_RULE();
1199
1200 /* Parent rule without consumers */
1201
1202 /* Unlink q from current list */
1203 q_next = q->next;
1204 if (q == V_ipfw_dyn_v[i].head)
1205 V_ipfw_dyn_v[i].head = q_next;
1206 else
1207 q_prev->next = q_next;
1208
1209 q->next = NULL;
1210
1211 /* Add to expired list */
1212 *exptailp = q;
1213 exptailp = &(*exptailp)->next;
1214
1215 DEB(print_dyn_rule(&q->id, q->dyn_type,
1216 "unlink parent entry", "left");
1217 )
1218
1219 expired++;
1220
1221 q = q_next;
1222 }
1223 IPFW_BUCK_UNLOCK(i);
1224 }
1225 }
1226
1227#undef NEXT_RULE
1228
1229 if (timer != 0) {
1230 /*
1231 * Check if we need to resize hash:
1232 * if current number of states exceeds number of buckes in hash,
1233 * grow hash size to the minimum power of 2 which is bigger than
1234 * current states count. Limit hash size by 64k.
1235 */
1236 max_buckets = (V_dyn_buckets_max > 65536) ?
1237 65536 : V_dyn_buckets_max;
1238
1239 dyn_count = DYN_COUNT;
1240
1241 if ((dyn_count > V_curr_dyn_buckets * 2) &&
1242 (dyn_count < max_buckets)) {
1243 new_buckets = V_curr_dyn_buckets;
1244 while (new_buckets < dyn_count) {
1245 new_buckets *= 2;
1246
1247 if (new_buckets >= max_buckets)
1248 break;
1249 }
1250 }
1251
1252 IPFW_UH_WUNLOCK(chain);
1253 }
1254
1255 /* Finally delete old states ad limits if any */
1256 for (q = exp_head; q != NULL; q = q_next) {
1257 q_next = q->next;
1258 uma_zfree(V_ipfw_dyn_rule_zone, q);
1259 }
1260
1261 for (q = exp_lhead; q != NULL; q = q_next) {
1262 q_next = q->next;
1263 uma_zfree(V_ipfw_dyn_rule_zone, q);
1264 }
1265
1266 /*
1267 * The rest code MUST be called from timer routine only
1268 * without holding any locks
1269 */
1270 if (timer == 0)
1271 return;
1272
1273 /* Send keepalive packets if any */
1274 for (m = m0; m != NULL; m = mnext) {
1275 mnext = m->m_nextpkt;
1276 m->m_nextpkt = NULL;
1277 h = mtod(m, struct ip *);
1278 if (h->ip_v == 4)
1279 ip_output(m, NULL, NULL, 0, NULL, NULL);
1280#ifdef INET6
1281 else
1282 ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
1283#endif
1284 }
1285
1286 /* Run table resize without holding any locks */
1287 if (new_buckets != 0)
1288 resize_dynamic_table(chain, new_buckets);
1289}
1290
1291/*
1292 * Deletes all dynamic rules originated by given rule or all rules in
1293 * given set. Specify RESVD_SET to indicate set should not be used.
1294 * @chain - pointer to current ipfw rules chain
1295 * @rule - delete all states originated by given rule if != NULL
1296 * @set - delete all states originated by any rule in set @set if != RESVD_SET
1297 *
1298 * Function has to be called with IPFW_UH_WLOCK held.
1299 * Additionally, function assume that dynamic rule/set is
1300 * ALREADY deleted so no new states can be generated by
1301 * 'deleted' rules.
1302 */
1303void
1304ipfw_expire_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set)
1305{
1306
1307 check_dyn_rules(chain, rule, set, 0, 0);
1308}
1309
1310void
1311ipfw_dyn_init(struct ip_fw_chain *chain)
1312{
1313
1314 V_ipfw_dyn_v = NULL;
1315 V_dyn_buckets_max = 256; /* must be power of 2 */
1316 V_curr_dyn_buckets = 256; /* must be power of 2 */
1317
1318 V_dyn_ack_lifetime = 300;
1319 V_dyn_syn_lifetime = 20;
1320 V_dyn_fin_lifetime = 1;
1321 V_dyn_rst_lifetime = 1;
1322 V_dyn_udp_lifetime = 10;
1323 V_dyn_short_lifetime = 5;
1324
1325 V_dyn_keepalive_interval = 20;
1326 V_dyn_keepalive_period = 5;
1327 V_dyn_keepalive = 1; /* do send keepalives */
1328 V_dyn_keepalive_last = time_uptime;
1329
1330 V_dyn_max = 4096; /* max # of dynamic rules */
1331
1332 V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
1333 sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
1334 UMA_ALIGN_PTR, 0);
1335
1336 /* Enforce limit on dynamic rules */
1337 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1338
1339 callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
1340
1341 /*
1342 * This can potentially be done on first dynamic rule
1343 * being added to chain.
1344 */
1345 resize_dynamic_table(chain, V_curr_dyn_buckets);
1346}
1347
1348void
1349ipfw_dyn_uninit(int pass)
1350{
1351 int i;
1352
1353 if (pass == 0) {
1354 callout_drain(&V_ipfw_timeout);
1355 return;
1356 }
1357
1358 if (V_ipfw_dyn_v != NULL) {
1359 /*
1360 * Skip deleting all dynamic states -
1361 * uma_zdestroy() does this more efficiently;
1362 */
1363
1364 /* Destroy all mutexes */
1365 for (i = 0 ; i < V_curr_dyn_buckets ; i++)
1366 IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]);
1367 free(V_ipfw_dyn_v, M_IPFW);
1368 V_ipfw_dyn_v = NULL;
1369 }
1370
1371 uma_zdestroy(V_ipfw_dyn_rule_zone);
1372}
1373
1374#ifdef SYSCTL_NODE
1375/*
1376 * Get/set maximum number of dynamic states in given VNET instance.
1377 */
1378static int
1379sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS)
1380{
1381 int error;
1382 unsigned int nstates;
1383
1384 nstates = V_dyn_max;
1385
1386 error = sysctl_handle_int(oidp, &nstates, 0, req);
1387 /* Read operation or some error */
1388 if ((error != 0) || (req->newptr == NULL))
1389 return (error);
1390
1391 V_dyn_max = nstates;
1392 uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max);
1393
1394 return (0);
1395}
1396
1397/*
1398 * Get current number of dynamic states in given VNET instance.
1399 */
1400static int
1401sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS)
1402{
1403 int error;
1404 unsigned int nstates;
1405
1406 nstates = DYN_COUNT;
1407
1408 error = sysctl_handle_int(oidp, &nstates, 0, req);
1409
1410 return (error);
1411}
1412#endif
1413
1414/*
1415 * Returns number of dynamic rules.
1416 */
1417int
1418ipfw_dyn_len(void)
1419{
1420
1421 return (V_ipfw_dyn_v == NULL) ? 0 :
1422 (DYN_COUNT * sizeof(ipfw_dyn_rule));
1423}
1424
1425/*
1426 * Fill given buffer with dynamic states.
1427 * IPFW_UH_RLOCK has to be held while calling.
1428 */
1429void
1430ipfw_get_dynamic(struct ip_fw_chain *chain, char **pbp, const char *ep)
1431{
1432 ipfw_dyn_rule *p, *last = NULL;
1433 char *bp;
1434 int i;
1435
1436 if (V_ipfw_dyn_v == NULL)
1437 return;
1438 bp = *pbp;
1439
1440 IPFW_UH_RLOCK_ASSERT(chain);
1441
1442 for (i = 0 ; i < V_curr_dyn_buckets; i++) {
1443 IPFW_BUCK_LOCK(i);
1444 for (p = V_ipfw_dyn_v[i].head ; p != NULL; p = p->next) {
1445 if (bp + sizeof *p <= ep) {
1446 ipfw_dyn_rule *dst =
1447 (ipfw_dyn_rule *)bp;
1448 bcopy(p, dst, sizeof *p);
1449 bcopy(&(p->rule->rulenum), &(dst->rule),
1450 sizeof(p->rule->rulenum));
1451 /*
1452 * store set number into high word of
1453 * dst->rule pointer.
1454 */
1455 bcopy(&(p->rule->set),
1456 (char *)&dst->rule +
1457 sizeof(p->rule->rulenum),
1458 sizeof(p->rule->set));
1459 /*
1460 * store a non-null value in "next".
1461 * The userland code will interpret a
1462 * NULL here as a marker
1463 * for the last dynamic rule.
1464 */
1465 bcopy(&dst, &dst->next, sizeof(dst));
1466 last = dst;
1467 dst->expire =
1468 TIME_LEQ(dst->expire, time_uptime) ?
1469 0 : dst->expire - time_uptime ;
1470 bp += sizeof(ipfw_dyn_rule);
1471 }
1472 }
1473 IPFW_BUCK_UNLOCK(i);
1474 }
1475
1476 if (last != NULL) /* mark last dynamic rule */
1477 bzero(&last->next, sizeof(last));
1478 *pbp = bp;
1479}
1480/* end of file */