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ip_flow.c revision 1.72 
      1 /*	$NetBSD: ip_flow.c,v 1.72 2016/06/20 06:46:38 knakahara 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 1.72 2016/06/20 06:46:38 knakahara 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 #define	IPFLOW_HASHBITS		6	/* should not be a multiple of 8 */
     67 
     68 static struct pool ipflow_pool;
     69 
     70 LIST_HEAD(ipflowhead, ipflow);
     71 
     72 #define	IPFLOW_TIMER		(5 * PR_SLOWHZ)
     73 #define	IPFLOW_DEFAULT_HASHSIZE	(1 << IPFLOW_HASHBITS)
     74 
     75 /*
     76  * ip_flow.c internal lock.
     77  * If we use softnet_lock, it would cause recursive lock.
     78  *
     79  * This is a tentative workaround.
     80  * We should make it scalable somehow in the future.
     81  */
     82 static kmutex_t ipflow_lock;
     83 static struct ipflowhead *ipflowtable = NULL;
     84 static struct ipflowhead ipflowlist;
     85 static int ipflow_inuse;
     86 
     87 #define	IPFLOW_INSERT(bucket, ipf) \
     88 do { \
     89 	LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
     90 	LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
     91 } while (/*CONSTCOND*/ 0)
     92 
     93 #define	IPFLOW_REMOVE(ipf) \
     94 do { \
     95 	LIST_REMOVE((ipf), ipf_hash); \
     96 	LIST_REMOVE((ipf), ipf_list); \
     97 } while (/*CONSTCOND*/ 0)
     98 
     99 #ifndef IPFLOW_MAX
    100 #define	IPFLOW_MAX		256
    101 #endif
    102 static int ip_maxflows = IPFLOW_MAX;
    103 static int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE;
    104 
    105 static struct ipflow *ipflow_reap(bool);
    106 static void ipflow_sysctl_init(struct sysctllog **);
    107 
    108 static size_t
    109 ipflow_hash(const struct ip *ip)
    110 {
    111 	size_t hash = ip->ip_tos;
    112 	size_t idx;
    113 
    114 	for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) {
    115 		hash += (ip->ip_dst.s_addr >> (32 - idx)) +
    116 		    (ip->ip_src.s_addr >> idx);
    117 	}
    118 
    119 	return hash & (ip_hashsize-1);
    120 }
    121 
    122 static struct ipflow *
    123 ipflow_lookup(const struct ip *ip)
    124 {
    125 	size_t hash;
    126 	struct ipflow *ipf;
    127 
    128 	KASSERT(mutex_owned(&ipflow_lock));
    129 
    130 	hash = ipflow_hash(ip);
    131 
    132 	LIST_FOREACH(ipf, &ipflowtable[hash], ipf_hash) {
    133 		if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
    134 		    && ip->ip_src.s_addr == ipf->ipf_src.s_addr
    135 		    && ip->ip_tos == ipf->ipf_tos)
    136 			break;
    137 	}
    138 	return ipf;
    139 }
    140 
    141 void
    142 ipflow_poolinit(void)
    143 {
    144 
    145 	pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl",
    146 	    NULL, IPL_NET);
    147 }
    148 
    149 static int
    150 ipflow_reinit(int table_size)
    151 {
    152 	struct ipflowhead *new_table;
    153 	size_t i;
    154 
    155 	KASSERT(mutex_owned(&ipflow_lock));
    156 
    157 	new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) *
    158 	    table_size, M_RTABLE, M_NOWAIT);
    159 
    160 	if (new_table == NULL)
    161 		return 1;
    162 
    163 	if (ipflowtable != NULL)
    164 		free(ipflowtable, M_RTABLE);
    165 
    166 	ipflowtable = new_table;
    167 	ip_hashsize = table_size;
    168 
    169 	LIST_INIT(&ipflowlist);
    170 	for (i = 0; i < ip_hashsize; i++)
    171 		LIST_INIT(&ipflowtable[i]);
    172 
    173 	return 0;
    174 }
    175 
    176 void
    177 ipflow_init(void)
    178 {
    179 
    180 	mutex_init(&ipflow_lock, MUTEX_DEFAULT, IPL_NONE);
    181 
    182 	mutex_enter(&ipflow_lock);
    183 	(void)ipflow_reinit(ip_hashsize);
    184 	mutex_exit(&ipflow_lock);
    185 	ipflow_sysctl_init(NULL);
    186 }
    187 
    188 int
    189 ipflow_fastforward(struct mbuf *m)
    190 {
    191 	struct ip *ip;
    192 	struct ip ip_store;
    193 	struct ipflow *ipf;
    194 	struct rtentry *rt;
    195 	const struct sockaddr *dst;
    196 	int error;
    197 	int iplen;
    198 	struct ifnet *ifp;
    199 	int s;
    200 	int ret = 0;
    201 
    202 	mutex_enter(&ipflow_lock);
    203 	/*
    204 	 * Are we forwarding packets?  Big enough for an IP packet?
    205 	 */
    206 	if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
    207 		goto out;
    208 
    209 	/*
    210 	 * Was packet received as a link-level multicast or broadcast?
    211 	 * If so, don't try to fast forward..
    212 	 */
    213 	if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
    214 		goto out;
    215 
    216 	/*
    217 	 * IP header with no option and valid version and length
    218 	 */
    219 	if (IP_HDR_ALIGNED_P(mtod(m, const void *)))
    220 		ip = mtod(m, struct ip *);
    221 	else {
    222 		memcpy(&ip_store, mtod(m, const void *), sizeof(ip_store));
    223 		ip = &ip_store;
    224 	}
    225 	iplen = ntohs(ip->ip_len);
    226 	if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
    227 	    iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
    228 		goto out;
    229 	/*
    230 	 * Find a flow.
    231 	 */
    232 	if ((ipf = ipflow_lookup(ip)) == NULL)
    233 		goto out;
    234 
    235 	ifp = m_get_rcvif(m, &s);
    236 	/*
    237 	 * Verify the IP header checksum.
    238 	 */
    239 	switch (m->m_pkthdr.csum_flags &
    240 		((ifp->if_csum_flags_rx & M_CSUM_IPv4) |
    241 		 M_CSUM_IPv4_BAD)) {
    242 	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
    243 		m_put_rcvif(ifp, &s);
    244 		goto out;
    245 
    246 	case M_CSUM_IPv4:
    247 		/* Checksum was okay. */
    248 		break;
    249 
    250 	default:
    251 		/* Must compute it ourselves. */
    252 		if (in_cksum(m, sizeof(struct ip)) != 0) {
    253 			m_put_rcvif(ifp, &s);
    254 			goto out;
    255 		}
    256 		break;
    257 	}
    258 	m_put_rcvif(ifp, &s);
    259 
    260 	/*
    261 	 * Route and interface still up?
    262 	 */
    263 	if ((rt = rtcache_validate(&ipf->ipf_ro)) == NULL ||
    264 	    (rt->rt_ifp->if_flags & IFF_UP) == 0 ||
    265 	    (rt->rt_flags & (RTF_BLACKHOLE | RTF_BROADCAST)) != 0)
    266 		goto out;
    267 
    268 	/*
    269 	 * Packet size OK?  TTL?
    270 	 */
    271 	if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
    272 		goto out;
    273 
    274 	/*
    275 	 * Clear any in-bound checksum flags for this packet.
    276 	 */
    277 	m->m_pkthdr.csum_flags = 0;
    278 
    279 	/*
    280 	 * Everything checks out and so we can forward this packet.
    281 	 * Modify the TTL and incrementally change the checksum.
    282 	 *
    283 	 * This method of adding the checksum works on either endian CPU.
    284 	 * If htons() is inlined, all the arithmetic is folded; otherwise
    285 	 * the htons()s are combined by CSE due to the const attribute.
    286 	 *
    287 	 * Don't bother using HW checksumming here -- the incremental
    288 	 * update is pretty fast.
    289 	 */
    290 	ip->ip_ttl -= IPTTLDEC;
    291 	if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
    292 		ip->ip_sum -= ~htons(IPTTLDEC << 8);
    293 	else
    294 		ip->ip_sum += htons(IPTTLDEC << 8);
    295 
    296 	/*
    297 	 * Done modifying the header; copy it back, if necessary.
    298 	 *
    299 	 * XXX Use m_copyback_cow(9) here? --dyoung
    300 	 */
    301 	if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0)
    302 		memcpy(mtod(m, void *), &ip_store, sizeof(ip_store));
    303 
    304 	/*
    305 	 * Trim the packet in case it's too long..
    306 	 */
    307 	if (m->m_pkthdr.len > iplen) {
    308 		if (m->m_len == m->m_pkthdr.len) {
    309 			m->m_len = iplen;
    310 			m->m_pkthdr.len = iplen;
    311 		} else
    312 			m_adj(m, iplen - m->m_pkthdr.len);
    313 	}
    314 
    315 	/*
    316 	 * Send the packet on its way.  All we can get back is ENOBUFS
    317 	 */
    318 	ipf->ipf_uses++;
    319 	PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
    320 
    321 	if (rt->rt_flags & RTF_GATEWAY)
    322 		dst = rt->rt_gateway;
    323 	else
    324 		dst = rtcache_getdst(&ipf->ipf_ro);
    325 
    326 	if ((error = if_output_lock(rt->rt_ifp, rt->rt_ifp, m, dst, rt)) != 0) {
    327 		if (error == ENOBUFS)
    328 			ipf->ipf_dropped++;
    329 		else
    330 			ipf->ipf_errors++;
    331 	}
    332 	ret = 1;
    333  out:
    334 	mutex_exit(&ipflow_lock);
    335 	return ret;
    336 }
    337 
    338 static void
    340 ipflow_addstats(struct ipflow *ipf)
    341 {
    342 	struct rtentry *rt;
    343 	uint64_t *ips;
    344 
    345 	if ((rt = rtcache_validate(&ipf->ipf_ro)) != NULL)
    346 		rt->rt_use += ipf->ipf_uses;
    347 
    348 	ips = IP_STAT_GETREF();
    349 	ips[IP_STAT_CANTFORWARD] += ipf->ipf_errors + ipf->ipf_dropped;
    350 	ips[IP_STAT_TOTAL] += ipf->ipf_uses;
    351 	ips[IP_STAT_FORWARD] += ipf->ipf_uses;
    352 	ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
    353 	IP_STAT_PUTREF();
    354 }
    355 
    356 static void
    357 ipflow_free(struct ipflow *ipf)
    358 {
    359 
    360 	KASSERT(mutex_owned(&ipflow_lock));
    361 
    362 	/*
    363 	 * Remove the flow from the hash table (at elevated IPL).
    364 	 * Once it's off the list, we can deal with it at normal
    365 	 * network IPL.
    366 	 */
    367 	IPFLOW_REMOVE(ipf);
    368 
    369 	ipflow_addstats(ipf);
    370 	rtcache_free(&ipf->ipf_ro);
    371 	ipflow_inuse--;
    372 	pool_put(&ipflow_pool, ipf);
    373 }
    374 
    375 static struct ipflow *
    376 ipflow_reap(bool just_one)
    377 {
    378 
    379 	KASSERT(mutex_owned(&ipflow_lock));
    380 
    381 	while (just_one || ipflow_inuse > ip_maxflows) {
    382 		struct ipflow *ipf, *maybe_ipf = NULL;
    383 
    384 		ipf = LIST_FIRST(&ipflowlist);
    385 		while (ipf != NULL) {
    386 			/*
    387 			 * If this no longer points to a valid route
    388 			 * reclaim it.
    389 			 */
    390 			if (rtcache_validate(&ipf->ipf_ro) == NULL)
    391 				goto done;
    392 			/*
    393 			 * choose the one that's been least recently
    394 			 * used or has had the least uses in the
    395 			 * last 1.5 intervals.
    396 			 */
    397 			if (maybe_ipf == NULL ||
    398 			    ipf->ipf_timer < maybe_ipf->ipf_timer ||
    399 			    (ipf->ipf_timer == maybe_ipf->ipf_timer &&
    400 			     ipf->ipf_last_uses + ipf->ipf_uses <
    401 			         maybe_ipf->ipf_last_uses +
    402 			         maybe_ipf->ipf_uses))
    403 				maybe_ipf = ipf;
    404 			ipf = LIST_NEXT(ipf, ipf_list);
    405 		}
    406 		ipf = maybe_ipf;
    407 	    done:
    408 		/*
    409 		 * Remove the entry from the flow table.
    410 		 */
    411 		IPFLOW_REMOVE(ipf);
    412 
    413 		ipflow_addstats(ipf);
    414 		rtcache_free(&ipf->ipf_ro);
    415 		if (just_one)
    416 			return ipf;
    417 		pool_put(&ipflow_pool, ipf);
    418 		ipflow_inuse--;
    419 	}
    420 	return NULL;
    421 }
    422 
    423 void
    424 ipflow_slowtimo(void)
    425 {
    426 	struct rtentry *rt;
    427 	struct ipflow *ipf, *next_ipf;
    428 	uint64_t *ips;
    429 
    430 	mutex_enter(softnet_lock);
    431 	mutex_enter(&ipflow_lock);
    432 	KERNEL_LOCK(1, NULL);
    433 	for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
    434 		next_ipf = LIST_NEXT(ipf, ipf_list);
    435 		if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) ||
    436 		    (rt = rtcache_validate(&ipf->ipf_ro)) == NULL) {
    437 			ipflow_free(ipf);
    438 		} else {
    439 			ipf->ipf_last_uses = ipf->ipf_uses;
    440 			rt->rt_use += ipf->ipf_uses;
    441 			ips = IP_STAT_GETREF();
    442 			ips[IP_STAT_TOTAL] += ipf->ipf_uses;
    443 			ips[IP_STAT_FORWARD] += ipf->ipf_uses;
    444 			ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
    445 			IP_STAT_PUTREF();
    446 			ipf->ipf_uses = 0;
    447 		}
    448 	}
    449 	KERNEL_UNLOCK_ONE(NULL);
    450 	mutex_exit(&ipflow_lock);
    451 	mutex_exit(softnet_lock);
    452 }
    453 
    454 void
    455 ipflow_create(const struct route *ro, struct mbuf *m)
    456 {
    457 	const struct ip *const ip = mtod(m, const struct ip *);
    458 	struct ipflow *ipf;
    459 	size_t hash;
    460 
    461 	mutex_enter(&ipflow_lock);
    462 
    463 	/*
    464 	 * Don't create cache entries for ICMP messages.
    465 	 */
    466 	if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) {
    467 		mutex_exit(&ipflow_lock);
    468 		return;
    469 	}
    470 
    471 	KERNEL_LOCK(1, NULL);
    472 
    473 	/*
    474 	 * See if an existing flow struct exists.  If so remove it from its
    475 	 * list and free the old route.  If not, try to malloc a new one
    476 	 * (if we aren't at our limit).
    477 	 */
    478 	ipf = ipflow_lookup(ip);
    479 	if (ipf == NULL) {
    480 		if (ipflow_inuse >= ip_maxflows) {
    481 			ipf = ipflow_reap(true);
    482 		} else {
    483 			ipf = pool_get(&ipflow_pool, PR_NOWAIT);
    484 			if (ipf == NULL)
    485 				goto out;
    486 			ipflow_inuse++;
    487 		}
    488 		memset(ipf, 0, sizeof(*ipf));
    489 	} else {
    490 		IPFLOW_REMOVE(ipf);
    491 
    492 		ipflow_addstats(ipf);
    493 		rtcache_free(&ipf->ipf_ro);
    494 		ipf->ipf_uses = ipf->ipf_last_uses = 0;
    495 		ipf->ipf_errors = ipf->ipf_dropped = 0;
    496 	}
    497 
    498 	/*
    499 	 * Fill in the updated information.
    500 	 */
    501 	rtcache_copy(&ipf->ipf_ro, ro);
    502 	ipf->ipf_dst = ip->ip_dst;
    503 	ipf->ipf_src = ip->ip_src;
    504 	ipf->ipf_tos = ip->ip_tos;
    505 	PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
    506 
    507 	/*
    508 	 * Insert into the approriate bucket of the flow table.
    509 	 */
    510 	hash = ipflow_hash(ip);
    511 	IPFLOW_INSERT(&ipflowtable[hash], ipf);
    512 
    513  out:
    514 	KERNEL_UNLOCK_ONE(NULL);
    515 	mutex_exit(&ipflow_lock);
    516 }
    517 
    518 int
    519 ipflow_invalidate_all(int new_size)
    520 {
    521 	struct ipflow *ipf, *next_ipf;
    522 	int error;
    523 
    524 	error = 0;
    525 
    526 	mutex_enter(&ipflow_lock);
    527 
    528 	for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
    529 		next_ipf = LIST_NEXT(ipf, ipf_list);
    530 		ipflow_free(ipf);
    531 	}
    532 
    533 	if (new_size)
    534 		error = ipflow_reinit(new_size);
    535 
    536 	mutex_exit(&ipflow_lock);
    537 
    538 	return error;
    539 }
    540 
    541 #ifdef GATEWAY
    542 /*
    543  * sysctl helper routine for net.inet.ip.maxflows.
    544  */
    545 static int
    546 sysctl_net_inet_ip_maxflows(SYSCTLFN_ARGS)
    547 {
    548 	int error;
    549 
    550 	error = sysctl_lookup(SYSCTLFN_CALL(rnode));
    551 	if (error || newp == NULL)
    552 		return (error);
    553 
    554 	mutex_enter(softnet_lock);
    555 	mutex_enter(&ipflow_lock);
    556 	KERNEL_LOCK(1, NULL);
    557 
    558 	ipflow_reap(false);
    559 
    560 	KERNEL_UNLOCK_ONE(NULL);
    561 	mutex_exit(&ipflow_lock);
    562 	mutex_exit(softnet_lock);
    563 
    564 	return (0);
    565 }
    566 
    567 static int
    568 sysctl_net_inet_ip_hashsize(SYSCTLFN_ARGS)
    569 {
    570 	int error, tmp;
    571 	struct sysctlnode node;
    572 
    573 	node = *rnode;
    574 	tmp = ip_hashsize;
    575 	node.sysctl_data = &tmp;
    576 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
    577 	if (error || newp == NULL)
    578 		return (error);
    579 
    580 	if ((tmp & (tmp - 1)) == 0 && tmp != 0) {
    581 		/*
    582 		 * Can only fail due to malloc()
    583 		 */
    584 		mutex_enter(softnet_lock);
    585 		KERNEL_LOCK(1, NULL);
    586 
    587 		error = ipflow_invalidate_all(tmp);
    588 
    589 		KERNEL_UNLOCK_ONE(NULL);
    590 		mutex_exit(softnet_lock);
    591 
    592 	} else {
    593 		/*
    594 		 * EINVAL if not a power of 2
    595 	         */
    596 		error = EINVAL;
    597 	}
    598 
    599 	return error;
    600 }
    601 #endif /* GATEWAY */
    602 
    603 static void
    604 ipflow_sysctl_init(struct sysctllog **clog)
    605 {
    606 	sysctl_createv(clog, 0, NULL, NULL,
    607 		       CTLFLAG_PERMANENT,
    608 		       CTLTYPE_NODE, "inet",
    609 		       SYSCTL_DESCR("PF_INET related settings"),
    610 		       NULL, 0, NULL, 0,
    611 		       CTL_NET, PF_INET, CTL_EOL);
    612 	sysctl_createv(clog, 0, NULL, NULL,
    613 		       CTLFLAG_PERMANENT,
    614 		       CTLTYPE_NODE, "ip",
    615 		       SYSCTL_DESCR("IPv4 related settings"),
    616 		       NULL, 0, NULL, 0,
    617 		       CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL);
    618 
    619 #ifdef GATEWAY
    620 	sysctl_createv(clog, 0, NULL, NULL,
    621 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    622 		       CTLTYPE_INT, "maxflows",
    623 		       SYSCTL_DESCR("Number of flows for fast forwarding"),
    624 		       sysctl_net_inet_ip_maxflows, 0, &ip_maxflows, 0,
    625 		       CTL_NET, PF_INET, IPPROTO_IP,
    626 		       IPCTL_MAXFLOWS, CTL_EOL);
    627 	sysctl_createv(clog, 0, NULL, NULL,
    628 			CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    629 			CTLTYPE_INT, "hashsize",
    630 			SYSCTL_DESCR("Size of hash table for fast forwarding (IPv4)"),
    631 			sysctl_net_inet_ip_hashsize, 0, &ip_hashsize, 0,
    632 			CTL_NET, PF_INET, IPPROTO_IP,
    633 			CTL_CREATE, CTL_EOL);
    634 #endif /* GATEWAY */
    635 }
    636