xref: /netbsd-src/sys/netinet6/ip6_flow.c (revision b7b7574d3bf8eeb51a1fa3977b59142ec6434a55) 
1 /*	$NetBSD: ip6_flow.c,v 1.23 2014/05/20 20:23:56 bouyer Exp $	*/
2 
3 /*-
4  * Copyright (c) 2007 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 Liam J. Foy
9  * <liamjfoy@netbsd.org> and Matt Thomas <matt@netbsd.org>.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  *
32  * IPv6 version was developed by Liam J. Foy. Original source existed in IPv4
33  * format developed by Matt Thomas. Thanks to Joerg Sonnenberger, Matt
34  * Thomas and Christos Zoulas.
35  *
36  * Thanks to Liverpool John Moores University, especially Dr. David Llewellyn-Jones
37  * for providing resources (to test) and Professor Madjid Merabti.
38  */
39 
40 #include <sys/cdefs.h>
41 __KERNEL_RCSID(0, "$NetBSD: ip6_flow.c,v 1.23 2014/05/20 20:23:56 bouyer Exp $");
42 
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/malloc.h>
46 #include <sys/mbuf.h>
47 #include <sys/domain.h>
48 #include <sys/protosw.h>
49 #include <sys/socket.h>
50 #include <sys/socketvar.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 <netinet6/in6_var.h>
63 #include <netinet/in_systm.h>
64 #include <netinet/ip6.h>
65 #include <netinet6/ip6_var.h>
66 #include <netinet6/ip6_private.h>
67 
68 /*
69  * IPv6 Fast Forward caches/hashes flows from one source to destination.
70  *
71  * Upon a successful forward IPv6FF caches and hashes details such as the
72  * route, source and destination. Once another packet is received matching
73  * the source and destination the packet is forwarded straight onto if_output
74  * using the cached details.
75  *
76  * Example:
77  * ether/fddi_input -> ip6flow_fastforward -> if_output
78  */
79 
80 static struct pool ip6flow_pool;
81 
82 LIST_HEAD(ip6flowhead, ip6flow);
83 
84 /*
85  * We could use IPv4 defines (IPFLOW_HASHBITS) but we'll
86  * use our own (possibly for future expansion).
87  */
88 #define	IP6FLOW_TIMER		(5 * PR_SLOWHZ)
89 #define	IP6FLOW_DEFAULT_HASHSIZE	(1 << IP6FLOW_HASHBITS)
90 
91 static struct ip6flowhead *ip6flowtable = NULL;
92 static struct ip6flowhead ip6flowlist;
93 static int ip6flow_inuse;
94 
95 /*
96  * Insert an ip6flow into the list.
97  */
98 #define	IP6FLOW_INSERT(bucket, ip6f) \
99 do { \
100 	LIST_INSERT_HEAD((bucket), (ip6f), ip6f_hash); \
101 	LIST_INSERT_HEAD(&ip6flowlist, (ip6f), ip6f_list); \
102 } while (/*CONSTCOND*/ 0)
103 
104 /*
105  * Remove an ip6flow from the list.
106  */
107 #define	IP6FLOW_REMOVE(ip6f) \
108 do { \
109 	LIST_REMOVE((ip6f), ip6f_hash); \
110 	LIST_REMOVE((ip6f), ip6f_list); \
111 } while (/*CONSTCOND*/ 0)
112 
113 #ifndef IP6FLOW_DEFAULT
114 #define	IP6FLOW_DEFAULT		256
115 #endif
116 
117 int ip6_maxflows = IP6FLOW_DEFAULT;
118 int ip6_hashsize = IP6FLOW_DEFAULT_HASHSIZE;
119 
120 /*
121  * Calculate hash table position.
122  */
123 static size_t
124 ip6flow_hash(const struct ip6_hdr *ip6)
125 {
126 	size_t hash;
127 	uint32_t dst_sum, src_sum;
128 	size_t idx;
129 
130 	src_sum = ip6->ip6_src.s6_addr32[0] + ip6->ip6_src.s6_addr32[1]
131 	    + ip6->ip6_src.s6_addr32[2] + ip6->ip6_src.s6_addr32[3];
132 	dst_sum = ip6->ip6_dst.s6_addr32[0] + ip6->ip6_dst.s6_addr32[1]
133 	    + ip6->ip6_dst.s6_addr32[2] + ip6->ip6_dst.s6_addr32[3];
134 
135 	hash = ip6->ip6_flow;
136 
137 	for (idx = 0; idx < 32; idx += IP6FLOW_HASHBITS)
138 		hash += (dst_sum >> (32 - idx)) + (src_sum >> idx);
139 
140 	return hash & (ip6_hashsize-1);
141 }
142 
143 /*
144  * Check to see if a flow already exists - if so return it.
145  */
146 static struct ip6flow *
147 ip6flow_lookup(const struct ip6_hdr *ip6)
148 {
149 	size_t hash;
150 	struct ip6flow *ip6f;
151 
152 	hash = ip6flow_hash(ip6);
153 
154 	LIST_FOREACH(ip6f, &ip6flowtable[hash], ip6f_hash) {
155 		if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6f->ip6f_dst)
156 		    && IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6f->ip6f_src)
157 		    && ip6f->ip6f_flow == ip6->ip6_flow) {
158 		    	/* A cached flow has been found. */
159 			return ip6f;
160 		}
161 	}
162 
163 	return NULL;
164 }
165 
166 void
167 ip6flow_poolinit(void)
168 {
169 
170 	pool_init(&ip6flow_pool, sizeof(struct ip6flow), 0, 0, 0, "ip6flowpl",
171 			NULL, IPL_NET);
172 }
173 
174 /*
175  * Allocate memory and initialise lists. This function is called
176  * from ip6_init and called there after to resize the hash table.
177  * If a newly sized table cannot be malloc'ed we just continue
178  * to use the old one.
179  */
180 int
181 ip6flow_init(int table_size)
182 {
183 	struct ip6flowhead *new_table;
184 	size_t i;
185 
186 	new_table = (struct ip6flowhead *)malloc(sizeof(struct ip6flowhead) *
187 	    table_size, M_RTABLE, M_NOWAIT);
188 
189 	if (new_table == NULL)
190 		return 1;
191 
192 	if (ip6flowtable != NULL)
193 		free(ip6flowtable, M_RTABLE);
194 
195 	ip6flowtable = new_table;
196 	ip6_hashsize = table_size;
197 
198 	LIST_INIT(&ip6flowlist);
199 	for (i = 0; i < ip6_hashsize; i++)
200 		LIST_INIT(&ip6flowtable[i]);
201 
202 	return 0;
203 }
204 
205 /*
206  * IPv6 Fast Forward routine. Attempt to forward the packet -
207  * if any problems are found return to the main IPv6 input
208  * routine to deal with.
209  */
210 int
211 ip6flow_fastforward(struct mbuf **mp)
212 {
213 	struct ip6flow *ip6f;
214 	struct ip6_hdr *ip6;
215 	struct rtentry *rt;
216 	struct mbuf *m;
217 	const struct sockaddr *dst;
218 	int error;
219 
220 	/*
221 	 * Are we forwarding packets and have flows?
222 	 */
223 	if (!ip6_forwarding || ip6flow_inuse == 0)
224 		return 0;
225 
226 	m = *mp;
227 	/*
228 	 * At least size of IPv6 Header?
229 	 */
230 	if (m->m_len < sizeof(struct ip6_hdr))
231 		return 0;
232 	/*
233 	 * Was packet received as a link-level multicast or broadcast?
234 	 * If so, don't try to fast forward.
235 	 */
236 	if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
237 		return 0;
238 
239 	if (IP6_HDR_ALIGNED_P(mtod(m, const void *)) == 0) {
240 		if ((m = m_copyup(m, sizeof(struct ip6_hdr),
241 				(max_linkhdr + 3) & ~3)) == NULL) {
242 			return 0;
243 		}
244 		*mp = m;
245 	} else if (__predict_false(m->m_len < sizeof(struct ip6_hdr))) {
246 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
247 			return 0;
248 		}
249 		*mp = m;
250 	}
251 
252 	ip6 = mtod(m, struct ip6_hdr *);
253 
254 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
255 		/* Bad version. */
256 		return 0;
257 	}
258 
259 	/*
260 	 * If we have a hop-by-hop extension we must process it.
261 	 * We just leave this up to ip6_input to deal with.
262 	 */
263 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS)
264 		return 0;
265 
266 	/*
267 	 * Attempt to find a flow.
268 	 */
269 	if ((ip6f = ip6flow_lookup(ip6)) == NULL) {
270 		/* No flow found. */
271 		return 0;
272 	}
273 
274 	/*
275 	 * Route and interface still up?
276 	 */
277 	if ((rt = rtcache_validate(&ip6f->ip6f_ro)) == NULL ||
278 	    (rt->rt_ifp->if_flags & IFF_UP) == 0) {
279 	    	/* Route or interface is down */
280 		return 0;
281 	}
282 
283 	/*
284 	 * Packet size greater than MTU?
285 	 */
286 	if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
287 		/* Return to main IPv6 input function. */
288 		return 0;
289 	}
290 
291 	/*
292 	 * Clear any in-bound checksum flags for this packet.
293 	 */
294 	m->m_pkthdr.csum_flags = 0;
295 
296 	if (ip6->ip6_hlim <= IPV6_HLIMDEC)
297 		return 0;
298 
299 	/* Decrement hop limit (same as TTL) */
300 	ip6->ip6_hlim -= IPV6_HLIMDEC;
301 
302 	if (rt->rt_flags & RTF_GATEWAY)
303 		dst = rt->rt_gateway;
304 	else
305 		dst = rtcache_getdst(&ip6f->ip6f_ro);
306 
307 	PRT_SLOW_ARM(ip6f->ip6f_timer, IP6FLOW_TIMER);
308 
309 	ip6f->ip6f_uses++;
310 
311 	KERNEL_LOCK(1, NULL);
312 	/* Send on its way - straight to the interface output routine. */
313 	if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
314 		ip6f->ip6f_dropped++;
315 	} else {
316 		ip6f->ip6f_forwarded++;
317 	}
318 	KERNEL_UNLOCK_ONE(NULL);
319 	return 1;
320 }
321 
322 /*
323  * Add the IPv6 flow statistics to the main IPv6 statistics.
324  */
325 static void
326 ip6flow_addstats(const struct ip6flow *ip6f)
327 {
328 	struct rtentry *rt;
329 	uint64_t *ip6s;
330 
331 	if ((rt = rtcache_validate(&ip6f->ip6f_ro)) != NULL)
332 		rt->rt_use += ip6f->ip6f_uses;
333 	ip6s = IP6_STAT_GETREF();
334 	ip6s[IP6_STAT_FASTFORWARDFLOWS] = ip6flow_inuse;
335 	ip6s[IP6_STAT_CANTFORWARD] += ip6f->ip6f_dropped;
336 	ip6s[IP6_STAT_ODROPPED] += ip6f->ip6f_dropped;
337 	ip6s[IP6_STAT_TOTAL] += ip6f->ip6f_uses;
338 	ip6s[IP6_STAT_FORWARD] += ip6f->ip6f_forwarded;
339 	ip6s[IP6_STAT_FASTFORWARD] += ip6f->ip6f_forwarded;
340 	IP6_STAT_PUTREF();
341 }
342 
343 /*
344  * Add statistics and free the flow.
345  */
346 static void
347 ip6flow_free(struct ip6flow *ip6f)
348 {
349 	int s;
350 
351 	/*
352 	 * Remove the flow from the hash table (at elevated IPL).
353 	 * Once it's off the list, we can deal with it at normal
354 	 * network IPL.
355 	 */
356 	s = splnet();
357 	IP6FLOW_REMOVE(ip6f);
358 	splx(s);
359 	ip6flow_inuse--;
360 	ip6flow_addstats(ip6f);
361 	rtcache_free(&ip6f->ip6f_ro);
362 	pool_put(&ip6flow_pool, ip6f);
363 }
364 
365 /*
366  * Reap one or more flows - ip6flow_reap may remove
367  * multiple flows if net.inet6.ip6.maxflows is reduced.
368  */
369 struct ip6flow *
370 ip6flow_reap(int just_one)
371 {
372 	while (just_one || ip6flow_inuse > ip6_maxflows) {
373 		struct ip6flow *ip6f, *maybe_ip6f = NULL;
374 		int s;
375 
376 		ip6f = LIST_FIRST(&ip6flowlist);
377 		while (ip6f != NULL) {
378 			/*
379 			 * If this no longer points to a valid route -
380 			 * reclaim it.
381 			 */
382 			if (rtcache_validate(&ip6f->ip6f_ro) == NULL)
383 				goto done;
384 			/*
385 			 * choose the one that's been least recently
386 			 * used or has had the least uses in the
387 			 * last 1.5 intervals.
388 			 */
389 			if (maybe_ip6f == NULL ||
390 			    ip6f->ip6f_timer < maybe_ip6f->ip6f_timer ||
391 			    (ip6f->ip6f_timer == maybe_ip6f->ip6f_timer &&
392 			     ip6f->ip6f_last_uses + ip6f->ip6f_uses <
393 			         maybe_ip6f->ip6f_last_uses +
394 			         maybe_ip6f->ip6f_uses))
395 				maybe_ip6f = ip6f;
396 			ip6f = LIST_NEXT(ip6f, ip6f_list);
397 		}
398 		ip6f = maybe_ip6f;
399 	    done:
400 		/*
401 		 * Remove the entry from the flow table
402 		 */
403 		s = splnet();
404 		IP6FLOW_REMOVE(ip6f);
405 		splx(s);
406 		rtcache_free(&ip6f->ip6f_ro);
407 		if (just_one) {
408 			ip6flow_addstats(ip6f);
409 			return ip6f;
410 		}
411 		ip6flow_inuse--;
412 		ip6flow_addstats(ip6f);
413 		pool_put(&ip6flow_pool, ip6f);
414 	}
415 	return NULL;
416 }
417 
418 void
419 ip6flow_slowtimo(void)
420 {
421 	struct ip6flow *ip6f, *next_ip6f;
422 
423 	mutex_enter(softnet_lock);
424 	KERNEL_LOCK(1, NULL);
425 
426 	for (ip6f = LIST_FIRST(&ip6flowlist); ip6f != NULL; ip6f = next_ip6f) {
427 		next_ip6f = LIST_NEXT(ip6f, ip6f_list);
428 		if (PRT_SLOW_ISEXPIRED(ip6f->ip6f_timer) ||
429 		    rtcache_validate(&ip6f->ip6f_ro) == NULL) {
430 			ip6flow_free(ip6f);
431 		} else {
432 			ip6f->ip6f_last_uses = ip6f->ip6f_uses;
433 			ip6flow_addstats(ip6f);
434 			ip6f->ip6f_uses = 0;
435 			ip6f->ip6f_dropped = 0;
436 			ip6f->ip6f_forwarded = 0;
437 		}
438 	}
439 
440 	KERNEL_UNLOCK_ONE(NULL);
441 	mutex_exit(softnet_lock);
442 }
443 
444 /*
445  * We have successfully forwarded a packet using the normal
446  * IPv6 stack. Now create/update a flow.
447  */
448 void
449 ip6flow_create(const struct route *ro, struct mbuf *m)
450 {
451 	const struct ip6_hdr *ip6;
452 	struct ip6flow *ip6f;
453 	size_t hash;
454 	int s;
455 
456 	ip6 = mtod(m, const struct ip6_hdr *);
457 
458 	/*
459 	 * If IPv6 Fast Forward is disabled, don't create a flow.
460 	 * It can be disabled by setting net.inet6.ip6.maxflows to 0.
461 	 *
462 	 * Don't create a flow for ICMPv6 messages.
463 	 */
464 	if (ip6_maxflows == 0 || ip6->ip6_nxt == IPPROTO_IPV6_ICMP)
465 		return;
466 
467 	KERNEL_LOCK(1, NULL);
468 
469 	/*
470 	 * See if an existing flow exists.  If so:
471 	 *	- Remove the flow
472 	 *	- Add flow statistics
473 	 *	- Free the route
474 	 *	- Reset statistics
475 	 *
476 	 * If a flow doesn't exist allocate a new one if
477 	 * ip6_maxflows hasn't reached its limit. If it has
478 	 * been reached, reap some flows.
479 	 */
480 	ip6f = ip6flow_lookup(ip6);
481 	if (ip6f == NULL) {
482 		if (ip6flow_inuse >= ip6_maxflows) {
483 			ip6f = ip6flow_reap(1);
484 		} else {
485 			ip6f = pool_get(&ip6flow_pool, PR_NOWAIT);
486 			if (ip6f == NULL)
487 				goto out;
488 			ip6flow_inuse++;
489 		}
490 		memset(ip6f, 0, sizeof(*ip6f));
491 	} else {
492 		s = splnet();
493 		IP6FLOW_REMOVE(ip6f);
494 		splx(s);
495 		ip6flow_addstats(ip6f);
496 		rtcache_free(&ip6f->ip6f_ro);
497 		ip6f->ip6f_uses = 0;
498 		ip6f->ip6f_last_uses = 0;
499 		ip6f->ip6f_dropped = 0;
500 		ip6f->ip6f_forwarded = 0;
501 	}
502 
503 	/*
504 	 * Fill in the updated/new details.
505 	 */
506 	rtcache_copy(&ip6f->ip6f_ro, ro);
507 	ip6f->ip6f_dst = ip6->ip6_dst;
508 	ip6f->ip6f_src = ip6->ip6_src;
509 	ip6f->ip6f_flow = ip6->ip6_flow;
510 	PRT_SLOW_ARM(ip6f->ip6f_timer, IP6FLOW_TIMER);
511 
512 	/*
513 	 * Insert into the approriate bucket of the flow table.
514 	 */
515 	hash = ip6flow_hash(ip6);
516 	s = splnet();
517 	IP6FLOW_INSERT(&ip6flowtable[hash], ip6f);
518 	splx(s);
519 
520  out:
521 	KERNEL_UNLOCK_ONE(NULL);
522 }
523 
524 /*
525  * Invalidate/remove all flows - if new_size is positive we
526  * resize the hash table.
527  */
528 int
529 ip6flow_invalidate_all(int new_size)
530 {
531 	struct ip6flow *ip6f, *next_ip6f;
532 	int s, error;
533 
534 	error = 0;
535 	s = splnet();
536 	for (ip6f = LIST_FIRST(&ip6flowlist); ip6f != NULL; ip6f = next_ip6f) {
537 		next_ip6f = LIST_NEXT(ip6f, ip6f_list);
538 		ip6flow_free(ip6f);
539 	}
540 
541 	if (new_size)
542 		error = ip6flow_init(new_size);
543 	splx(s);
544 
545 	return error;
546 }
547