FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_flow.c
1 /* $NetBSD: ip_flow.c,v 1.56 2008/04/28 20:24:09 martin Exp $ */
2
3 /*-
4 * Copyright (c) 1998 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by the 3am Software Foundry ("3am"). It was developed by Matt Thomas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.56 2008/04/28 20:24:09 martin Exp $");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/domain.h>
40 #include <sys/protosw.h>
41 #include <sys/socket.h>
42 #include <sys/socketvar.h>
43 #include <sys/errno.h>
44 #include <sys/time.h>
45 #include <sys/kernel.h>
46 #include <sys/pool.h>
47 #include <sys/sysctl.h>
48
49 #include <net/if.h>
50 #include <net/if_dl.h>
51 #include <net/route.h>
52 #include <net/pfil.h>
53
54 #include <netinet/in.h>
55 #include <netinet/in_systm.h>
56 #include <netinet/ip.h>
57 #include <netinet/in_pcb.h>
58 #include <netinet/in_var.h>
59 #include <netinet/ip_var.h>
60 #include <netinet/ip_private.h>
61
62 /*
63 * Similar code is very well commented in netinet6/ip6_flow.c
64 */
65
66 struct ipflow {
67 LIST_ENTRY(ipflow) ipf_list; /* next in active list */
68 LIST_ENTRY(ipflow) ipf_hash; /* next ipflow in bucket */
69 struct in_addr ipf_dst; /* destination address */
70 struct in_addr ipf_src; /* source address */
71 uint8_t ipf_tos; /* type-of-service */
72 struct route ipf_ro; /* associated route entry */
73 u_long ipf_uses; /* number of uses in this period */
74 u_long ipf_last_uses; /* number of uses in last period */
75 u_long ipf_dropped; /* ENOBUFS retured by if_output */
76 u_long ipf_errors; /* other errors returned by if_output */
77 u_int ipf_timer; /* lifetime timer */
78 time_t ipf_start; /* creation time */
79 };
80
81 #define IPFLOW_HASHBITS 6 /* should not be a multiple of 8 */
82
83 POOL_INIT(ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", NULL,
84 IPL_NET);
85
86 LIST_HEAD(ipflowhead, ipflow);
87
88 #define IPFLOW_TIMER (5 * PR_SLOWHZ)
89 #define IPFLOW_DEFAULT_HASHSIZE (1 << IPFLOW_HASHBITS)
90
91 static struct ipflowhead *ipflowtable = NULL;
92 static struct ipflowhead ipflowlist;
93 static int ipflow_inuse;
94
95 #define IPFLOW_INSERT(bucket, ipf) \
96 do { \
97 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
98 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
99 } while (/*CONSTCOND*/ 0)
100
101 #define IPFLOW_REMOVE(ipf) \
102 do { \
103 LIST_REMOVE((ipf), ipf_hash); \
104 LIST_REMOVE((ipf), ipf_list); \
105 } while (/*CONSTCOND*/ 0)
106
107 #ifndef IPFLOW_MAX
108 #define IPFLOW_MAX 256
109 #endif
110 int ip_maxflows = IPFLOW_MAX;
111 int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE;
112
113 static size_t
114 ipflow_hash(const struct ip *ip)
115 {
116 size_t hash = ip->ip_tos;
117 size_t idx;
118
119 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) {
120 hash += (ip->ip_dst.s_addr >> (32 - idx)) +
121 (ip->ip_src.s_addr >> idx);
122 }
123
124 return hash & (ip_hashsize-1);
125 }
126
127 static struct ipflow *
128 ipflow_lookup(const struct ip *ip)
129 {
130 size_t hash;
131 struct ipflow *ipf;
132
133 hash = ipflow_hash(ip);
134
135 LIST_FOREACH(ipf, &ipflowtable[hash], ipf_hash) {
136 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
137 && ip->ip_src.s_addr == ipf->ipf_src.s_addr
138 && ip->ip_tos == ipf->ipf_tos)
139 break;
140 }
141 return ipf;
142 }
143
144 int
145 ipflow_init(int table_size)
146 {
147 struct ipflowhead *new_table;
148 size_t i;
149
150 new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) *
151 table_size, M_RTABLE, M_NOWAIT);
152
153 if (new_table == NULL)
154 return 1;
155
156 if (ipflowtable != NULL)
157 free(ipflowtable, M_RTABLE);
158
159 ipflowtable = new_table;
160 ip_hashsize = table_size;
161
162 LIST_INIT(&ipflowlist);
163 for (i = 0; i < ip_hashsize; i++)
164 LIST_INIT(&ipflowtable[i]);
165
166 return 0;
167 }
168
169 int
170 ipflow_fastforward(struct mbuf *m)
171 {
172 struct ip *ip;
173 struct ip ip_store;
174 struct ipflow *ipf;
175 struct rtentry *rt;
176 const struct sockaddr *dst;
177 int error;
178 int iplen;
179
180 /*
181 * Are we forwarding packets? Big enough for an IP packet?
182 */
183 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
184 return 0;
185
186 /*
187 * Was packet received as a link-level multicast or broadcast?
188 * If so, don't try to fast forward..
189 */
190 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
191 return 0;
192
193 /*
194 * IP header with no option and valid version and length
195 */
196 if (IP_HDR_ALIGNED_P(mtod(m, const void *)))
197 ip = mtod(m, struct ip *);
198 else {
199 memcpy(&ip_store, mtod(m, const void *), sizeof(ip_store));
200 ip = &ip_store;
201 }
202 iplen = ntohs(ip->ip_len);
203 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
204 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
205 return 0;
206 /*
207 * Find a flow.
208 */
209 if ((ipf = ipflow_lookup(ip)) == NULL)
210 return 0;
211
212 /*
213 * Verify the IP header checksum.
214 */
215 switch (m->m_pkthdr.csum_flags &
216 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
217 M_CSUM_IPv4_BAD)) {
218 case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
219 return (0);
220
221 case M_CSUM_IPv4:
222 /* Checksum was okay. */
223 break;
224
225 default:
226 /* Must compute it ourselves. */
227 if (in_cksum(m, sizeof(struct ip)) != 0)
228 return (0);
229 break;
230 }
231
232 /*
233 * Route and interface still up?
234 */
235 if ((rt = rtcache_validate(&ipf->ipf_ro)) == NULL ||
236 (rt->rt_ifp->if_flags & IFF_UP) == 0)
237 return 0;
238
239 /*
240 * Packet size OK? TTL?
241 */
242 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
243 return 0;
244
245 /*
246 * Clear any in-bound checksum flags for this packet.
247 */
248 m->m_pkthdr.csum_flags = 0;
249
250 /*
251 * Everything checks out and so we can forward this packet.
252 * Modify the TTL and incrementally change the checksum.
253 *
254 * This method of adding the checksum works on either endian CPU.
255 * If htons() is inlined, all the arithmetic is folded; otherwise
256 * the htons()s are combined by CSE due to the const attribute.
257 *
258 * Don't bother using HW checksumming here -- the incremental
259 * update is pretty fast.
260 */
261 ip->ip_ttl -= IPTTLDEC;
262 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
263 ip->ip_sum -= ~htons(IPTTLDEC << 8);
264 else
265 ip->ip_sum += htons(IPTTLDEC << 8);
266
267 /*
268 * Done modifying the header; copy it back, if necessary.
269 *
270 * XXX Use m_copyback_cow(9) here? --dyoung
271 */
272 if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0)
273 memcpy(mtod(m, void *), &ip_store, sizeof(ip_store));
274
275 /*
276 * Trim the packet in case it's too long..
277 */
278 if (m->m_pkthdr.len > iplen) {
279 if (m->m_len == m->m_pkthdr.len) {
280 m->m_len = iplen;
281 m->m_pkthdr.len = iplen;
282 } else
283 m_adj(m, iplen - m->m_pkthdr.len);
284 }
285
286 /*
287 * Send the packet on it's way. All we can get back is ENOBUFS
288 */
289 ipf->ipf_uses++;
290 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
291
292 if (rt->rt_flags & RTF_GATEWAY)
293 dst = rt->rt_gateway;
294 else
295 dst = rtcache_getdst(&ipf->ipf_ro);
296
297 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
298 if (error == ENOBUFS)
299 ipf->ipf_dropped++;
300 else
301 ipf->ipf_errors++;
302 }
303 return 1;
304 }
305
306 static void
307 ipflow_addstats(struct ipflow *ipf)
308 {
309 struct rtentry *rt;
310 uint64_t *ips;
311
312 if ((rt = rtcache_validate(&ipf->ipf_ro)) != NULL)
313 rt->rt_use += ipf->ipf_uses;
314
315 ips = IP_STAT_GETREF();
316 ips[IP_STAT_CANTFORWARD] += ipf->ipf_errors + ipf->ipf_dropped;
317 ips[IP_STAT_TOTAL] += ipf->ipf_uses;
318 ips[IP_STAT_FORWARD] += ipf->ipf_uses;
319 ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
320 IP_STAT_PUTREF();
321 }
322
323 static void
324 ipflow_free(struct ipflow *ipf)
325 {
326 int s;
327 /*
328 * Remove the flow from the hash table (at elevated IPL).
329 * Once it's off the list, we can deal with it at normal
330 * network IPL.
331 */
332 s = splnet();
333 IPFLOW_REMOVE(ipf);
334 splx(s);
335 ipflow_addstats(ipf);
336 rtcache_free(&ipf->ipf_ro);
337 ipflow_inuse--;
338 s = splnet();
339 pool_put(&ipflow_pool, ipf);
340 splx(s);
341 }
342
343 static struct ipflow *
344 ipflow_reap(bool just_one)
345 {
346 while (just_one || ipflow_inuse > ip_maxflows) {
347 struct ipflow *ipf, *maybe_ipf = NULL;
348 int s;
349
350 ipf = LIST_FIRST(&ipflowlist);
351 while (ipf != NULL) {
352 /*
353 * If this no longer points to a valid route
354 * reclaim it.
355 */
356 if (rtcache_validate(&ipf->ipf_ro) == NULL)
357 goto done;
358 /*
359 * choose the one that's been least recently
360 * used or has had the least uses in the
361 * last 1.5 intervals.
362 */
363 if (maybe_ipf == NULL ||
364 ipf->ipf_timer < maybe_ipf->ipf_timer ||
365 (ipf->ipf_timer == maybe_ipf->ipf_timer &&
366 ipf->ipf_last_uses + ipf->ipf_uses <
367 maybe_ipf->ipf_last_uses +
368 maybe_ipf->ipf_uses))
369 maybe_ipf = ipf;
370 ipf = LIST_NEXT(ipf, ipf_list);
371 }
372 ipf = maybe_ipf;
373 done:
374 /*
375 * Remove the entry from the flow table.
376 */
377 s = splnet();
378 IPFLOW_REMOVE(ipf);
379 splx(s);
380 ipflow_addstats(ipf);
381 rtcache_free(&ipf->ipf_ro);
382 if (just_one)
383 return ipf;
384 pool_put(&ipflow_pool, ipf);
385 ipflow_inuse--;
386 }
387 return NULL;
388 }
389
390 void
391 ipflow_prune(void)
392 {
393
394 (void) ipflow_reap(false);
395 }
396
397 void
398 ipflow_slowtimo(void)
399 {
400 struct rtentry *rt;
401 struct ipflow *ipf, *next_ipf;
402 uint64_t *ips;
403
404 mutex_enter(softnet_lock);
405 KERNEL_LOCK(1, NULL);
406 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
407 next_ipf = LIST_NEXT(ipf, ipf_list);
408 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) ||
409 (rt = rtcache_validate(&ipf->ipf_ro)) == NULL) {
410 ipflow_free(ipf);
411 } else {
412 ipf->ipf_last_uses = ipf->ipf_uses;
413 rt->rt_use += ipf->ipf_uses;
414 ips = IP_STAT_GETREF();
415 ips[IP_STAT_TOTAL] += ipf->ipf_uses;
416 ips[IP_STAT_FORWARD] += ipf->ipf_uses;
417 ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
418 IP_STAT_PUTREF();
419 ipf->ipf_uses = 0;
420 }
421 }
422 KERNEL_UNLOCK_ONE(NULL);
423 mutex_exit(softnet_lock);
424 }
425
426 void
427 ipflow_create(const struct route *ro, struct mbuf *m)
428 {
429 const struct ip *const ip = mtod(m, const struct ip *);
430 struct ipflow *ipf;
431 size_t hash;
432 int s;
433
434 /*
435 * Don't create cache entries for ICMP messages.
436 */
437 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
438 return;
439 /*
440 * See if an existing flow struct exists. If so remove it from it's
441 * list and free the old route. If not, try to malloc a new one
442 * (if we aren't at our limit).
443 */
444 ipf = ipflow_lookup(ip);
445 if (ipf == NULL) {
446 if (ipflow_inuse >= ip_maxflows) {
447 ipf = ipflow_reap(true);
448 } else {
449 s = splnet();
450 ipf = pool_get(&ipflow_pool, PR_NOWAIT);
451 splx(s);
452 if (ipf == NULL)
453 return;
454 ipflow_inuse++;
455 }
456 memset(ipf, 0, sizeof(*ipf));
457 } else {
458 s = splnet();
459 IPFLOW_REMOVE(ipf);
460 splx(s);
461 ipflow_addstats(ipf);
462 rtcache_free(&ipf->ipf_ro);
463 ipf->ipf_uses = ipf->ipf_last_uses = 0;
464 ipf->ipf_errors = ipf->ipf_dropped = 0;
465 }
466
467 /*
468 * Fill in the updated information.
469 */
470 rtcache_copy(&ipf->ipf_ro, ro);
471 ipf->ipf_dst = ip->ip_dst;
472 ipf->ipf_src = ip->ip_src;
473 ipf->ipf_tos = ip->ip_tos;
474 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
475 ipf->ipf_start = time_uptime;
476 /*
477 * Insert into the approriate bucket of the flow table.
478 */
479 hash = ipflow_hash(ip);
480 s = splnet();
481 IPFLOW_INSERT(&ipflowtable[hash], ipf);
482 splx(s);
483 }
484
485 int
486 ipflow_invalidate_all(int new_size)
487 {
488 struct ipflow *ipf, *next_ipf;
489 int s, error;
490
491 error = 0;
492 s = splnet();
493 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
494 next_ipf = LIST_NEXT(ipf, ipf_list);
495 ipflow_free(ipf);
496 }
497
498 if (new_size)
499 error = ipflow_init(new_size);
500 splx(s);
501
502 return error;
503 }
Cache object: ef8ac3cb32feed1c19242a69f6d93efc
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