ip_flow.c revision 1.48 1 /* $NetBSD: ip_flow.c,v 1.48 2007/08/20 19:42:34 dyoung 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 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 #include <sys/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.48 2007/08/20 19:42:34 dyoung Exp $");
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/malloc.h>
45 #include <sys/mbuf.h>
46 #include <sys/domain.h>
47 #include <sys/protosw.h>
48 #include <sys/socket.h>
49 #include <sys/socketvar.h>
50 #include <sys/errno.h>
51 #include <sys/time.h>
52 #include <sys/kernel.h>
53 #include <sys/pool.h>
54 #include <sys/sysctl.h>
55
56 #include <net/if.h>
57 #include <net/if_dl.h>
58 #include <net/route.h>
59 #include <net/pfil.h>
60
61 #include <netinet/in.h>
62 #include <netinet/in_systm.h>
63 #include <netinet/ip.h>
64 #include <netinet/in_pcb.h>
65 #include <netinet/in_var.h>
66 #include <netinet/ip_var.h>
67
68 /*
69 * Similar code is very well commented in netinet6/ip6_flow.c
70 */
71
72 POOL_INIT(ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", NULL,
73 IPL_NET);
74
75 LIST_HEAD(ipflowhead, ipflow);
76
77 #define IPFLOW_TIMER (5 * PR_SLOWHZ)
78 #define IPFLOW_DEFAULT_HASHSIZE (1 << IPFLOW_HASHBITS)
79
80 static struct ipflowhead *ipflowtable = NULL;
81 static struct ipflowhead ipflowlist;
82 static int ipflow_inuse;
83
84 #define IPFLOW_INSERT(bucket, ipf) \
85 do { \
86 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
87 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
88 } while (/*CONSTCOND*/ 0)
89
90 #define IPFLOW_REMOVE(ipf) \
91 do { \
92 LIST_REMOVE((ipf), ipf_hash); \
93 LIST_REMOVE((ipf), ipf_list); \
94 } while (/*CONSTCOND*/ 0)
95
96 #ifndef IPFLOW_MAX
97 #define IPFLOW_MAX 256
98 #endif
99 int ip_maxflows = IPFLOW_MAX;
100 int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE;
101
102 static size_t
103 ipflow_hash(struct ip *ip)
104 {
105 size_t hash = ip->ip_tos;
106 size_t idx;
107
108 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) {
109 hash += (ip->ip_dst.s_addr >> (32 - idx)) +
110 (ip->ip_src.s_addr >> idx);
111 }
112
113 return hash & (ip_hashsize-1);
114 }
115
116 static struct ipflow *
117 ipflow_lookup(struct ip *ip)
118 {
119 size_t hash;
120 struct ipflow *ipf;
121
122 hash = ipflow_hash(ip);
123
124 LIST_FOREACH(ipf, &ipflowtable[hash], ipf_hash) {
125 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
126 && ip->ip_src.s_addr == ipf->ipf_src.s_addr
127 && ip->ip_tos == ipf->ipf_tos)
128 break;
129 }
130 return ipf;
131 }
132
133 int
134 ipflow_init(int table_size)
135 {
136 struct ipflowhead *new_table;
137 size_t i;
138
139 new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) *
140 table_size, M_RTABLE, M_NOWAIT);
141
142 if (new_table == NULL)
143 return 1;
144
145 if (ipflowtable != NULL)
146 free(ipflowtable, M_RTABLE);
147
148 ipflowtable = new_table;
149 ip_hashsize = table_size;
150
151 LIST_INIT(&ipflowlist);
152 for (i = 0; i < ip_hashsize; i++)
153 LIST_INIT(&ipflowtable[i]);
154
155 return 0;
156 }
157
158 int
159 ipflow_fastforward(struct mbuf *m)
160 {
161 struct ip *ip, ip_store;
162 struct ipflow *ipf;
163 struct rtentry *rt;
164 const struct sockaddr *dst;
165 int error;
166 int iplen;
167
168 /*
169 * Are we forwarding packets? Big enough for an IP packet?
170 */
171 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
172 return 0;
173
174 /*
175 * Was packet received as a link-level multicast or broadcast?
176 * If so, don't try to fast forward..
177 */
178 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
179 return 0;
180
181 /*
182 * IP header with no option and valid version and length
183 */
184 if (IP_HDR_ALIGNED_P(mtod(m, void *)))
185 ip = mtod(m, struct ip *);
186 else {
187 memcpy(&ip_store, mtod(m, void *), sizeof(ip_store));
188 ip = &ip_store;
189 }
190 iplen = ntohs(ip->ip_len);
191 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
192 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
193 return 0;
194 /*
195 * Find a flow.
196 */
197 if ((ipf = ipflow_lookup(ip)) == NULL)
198 return 0;
199
200 /*
201 * Verify the IP header checksum.
202 */
203 switch (m->m_pkthdr.csum_flags &
204 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
205 M_CSUM_IPv4_BAD)) {
206 case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
207 return (0);
208
209 case M_CSUM_IPv4:
210 /* Checksum was okay. */
211 break;
212
213 default:
214 /* Must compute it ourselves. */
215 if (in_cksum(m, sizeof(struct ip)) != 0)
216 return (0);
217 break;
218 }
219
220 /*
221 * Route and interface still up?
222 */
223 if (rtcache_down(&ipf->ipf_ro) || (rt = ipf->ipf_ro.ro_rt) == NULL ||
224 (rt->rt_ifp->if_flags & IFF_UP) == 0)
225 return 0;
226
227 /*
228 * Packet size OK? TTL?
229 */
230 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
231 return 0;
232
233 /*
234 * Clear any in-bound checksum flags for this packet.
235 */
236 m->m_pkthdr.csum_flags = 0;
237
238 /*
239 * Everything checks out and so we can forward this packet.
240 * Modify the TTL and incrementally change the checksum.
241 *
242 * This method of adding the checksum works on either endian CPU.
243 * If htons() is inlined, all the arithmetic is folded; otherwise
244 * the htons()s are combined by CSE due to the const attribute.
245 *
246 * Don't bother using HW checksumming here -- the incremental
247 * update is pretty fast.
248 */
249 ip->ip_ttl -= IPTTLDEC;
250 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
251 ip->ip_sum -= ~htons(IPTTLDEC << 8);
252 else
253 ip->ip_sum += htons(IPTTLDEC << 8);
254
255 /*
256 * Done modifying the header; copy it back, if necessary.
257 */
258 if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0)
259 memcpy(mtod(m, void *), &ip_store, sizeof(ip_store));
260
261 /*
262 * Trim the packet in case it's too long..
263 */
264 if (m->m_pkthdr.len > iplen) {
265 if (m->m_len == m->m_pkthdr.len) {
266 m->m_len = iplen;
267 m->m_pkthdr.len = iplen;
268 } else
269 m_adj(m, iplen - m->m_pkthdr.len);
270 }
271
272 /*
273 * Send the packet on it's way. All we can get back is ENOBUFS
274 */
275 ipf->ipf_uses++;
276 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
277
278 if (rt->rt_flags & RTF_GATEWAY)
279 dst = rt->rt_gateway;
280 else
281 dst = rtcache_getdst(&ipf->ipf_ro);
282
283 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
284 if (error == ENOBUFS)
285 ipf->ipf_dropped++;
286 else
287 ipf->ipf_errors++;
288 }
289 return 1;
290 }
291
292 static void
294 ipflow_addstats(struct ipflow *ipf)
295 {
296 if (!rtcache_down(&ipf->ipf_ro) && ipf->ipf_ro.ro_rt != NULL)
297 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
298 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped;
299 ipstat.ips_total += ipf->ipf_uses;
300 ipstat.ips_forward += ipf->ipf_uses;
301 ipstat.ips_fastforward += ipf->ipf_uses;
302 }
303
304 static void
305 ipflow_free(struct ipflow *ipf)
306 {
307 int s;
308 /*
309 * Remove the flow from the hash table (at elevated IPL).
310 * Once it's off the list, we can deal with it at normal
311 * network IPL.
312 */
313 s = splnet();
314 IPFLOW_REMOVE(ipf);
315 splx(s);
316 ipflow_addstats(ipf);
317 rtcache_free(&ipf->ipf_ro);
318 ipflow_inuse--;
319 s = splnet();
320 pool_put(&ipflow_pool, ipf);
321 splx(s);
322 }
323
324 struct ipflow *
325 ipflow_reap(int just_one)
326 {
327 while (just_one || ipflow_inuse > ip_maxflows) {
328 struct ipflow *ipf, *maybe_ipf = NULL;
329 int s;
330
331 ipf = LIST_FIRST(&ipflowlist);
332 while (ipf != NULL) {
333 /*
334 * If this no longer points to a valid route
335 * reclaim it.
336 */
337 if (rtcache_down(&ipf->ipf_ro) ||
338 ipf->ipf_ro.ro_rt == NULL)
339 goto done;
340 /*
341 * choose the one that's been least recently
342 * used or has had the least uses in the
343 * last 1.5 intervals.
344 */
345 if (maybe_ipf == NULL ||
346 ipf->ipf_timer < maybe_ipf->ipf_timer ||
347 (ipf->ipf_timer == maybe_ipf->ipf_timer &&
348 ipf->ipf_last_uses + ipf->ipf_uses <
349 maybe_ipf->ipf_last_uses +
350 maybe_ipf->ipf_uses))
351 maybe_ipf = ipf;
352 ipf = LIST_NEXT(ipf, ipf_list);
353 }
354 ipf = maybe_ipf;
355 done:
356 /*
357 * Remove the entry from the flow table.
358 */
359 s = splnet();
360 IPFLOW_REMOVE(ipf);
361 splx(s);
362 ipflow_addstats(ipf);
363 rtcache_free(&ipf->ipf_ro);
364 if (just_one)
365 return ipf;
366 pool_put(&ipflow_pool, ipf);
367 ipflow_inuse--;
368 }
369 return NULL;
370 }
371
372 void
373 ipflow_slowtimo(void)
374 {
375 struct ipflow *ipf, *next_ipf;
376
377 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
378 next_ipf = LIST_NEXT(ipf, ipf_list);
379 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) ||
380 rtcache_down(&ipf->ipf_ro) || ipf->ipf_ro.ro_rt == NULL) {
381 ipflow_free(ipf);
382 } else {
383 ipf->ipf_last_uses = ipf->ipf_uses;
384 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
385 ipstat.ips_total += ipf->ipf_uses;
386 ipstat.ips_forward += ipf->ipf_uses;
387 ipstat.ips_fastforward += ipf->ipf_uses;
388 ipf->ipf_uses = 0;
389 }
390 }
391 }
392
393 void
394 ipflow_create(const struct route *ro, struct mbuf *m)
395 {
396 struct ip *const ip = mtod(m, struct ip *);
397 struct ipflow *ipf;
398 size_t hash;
399 int s;
400
401 /*
402 * Don't create cache entries for ICMP messages.
403 */
404 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
405 return;
406 /*
407 * See if an existing flow struct exists. If so remove it from it's
408 * list and free the old route. If not, try to malloc a new one
409 * (if we aren't at our limit).
410 */
411 ipf = ipflow_lookup(ip);
412 if (ipf == NULL) {
413 if (ipflow_inuse >= ip_maxflows) {
414 ipf = ipflow_reap(1);
415 } else {
416 s = splnet();
417 ipf = pool_get(&ipflow_pool, PR_NOWAIT);
418 splx(s);
419 if (ipf == NULL)
420 return;
421 ipflow_inuse++;
422 }
423 memset(ipf, 0, sizeof(*ipf));
424 } else {
425 s = splnet();
426 IPFLOW_REMOVE(ipf);
427 splx(s);
428 ipflow_addstats(ipf);
429 rtcache_free(&ipf->ipf_ro);
430 ipf->ipf_uses = ipf->ipf_last_uses = 0;
431 ipf->ipf_errors = ipf->ipf_dropped = 0;
432 }
433
434 /*
435 * Fill in the updated information.
436 */
437 rtcache_copy(&ipf->ipf_ro, ro);
438 ipf->ipf_dst = ip->ip_dst;
439 ipf->ipf_src = ip->ip_src;
440 ipf->ipf_tos = ip->ip_tos;
441 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
442 ipf->ipf_start = time_uptime;
443 /*
444 * Insert into the approriate bucket of the flow table.
445 */
446 hash = ipflow_hash(ip);
447 s = splnet();
448 IPFLOW_INSERT(&ipflowtable[hash], ipf);
449 splx(s);
450 }
451
452 int
453 ipflow_invalidate_all(int new_size)
454 {
455 struct ipflow *ipf, *next_ipf;
456 int s, error;
457
458 error = 0;
459 s = splnet();
460 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
461 next_ipf = LIST_NEXT(ipf, ipf_list);
462 ipflow_free(ipf);
463 }
464
465 if (new_size)
466 error = ipflow_init(new_size);
467 splx(s);
468
469 return error;
470 }
471