bsd/netinet/ip_flow.c

   1 /*
   2  * Copyright (c) 2000,2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*-
  29  * Copyright (c) 1998 The NetBSD Foundation, Inc.
  30  * All rights reserved.
  31  *
  32  * This code is derived from software contributed to The NetBSD Foundation
  33  * by the 3am Software Foundry ("3am").  It was developed by Matt Thomas.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  * 3. All advertising materials mentioning features or use of this software
  44  *    must display the following acknowledgement:
  45  *      This product includes software developed by the NetBSD
  46  *      Foundation, Inc. and its contributors.
  47  * 4. Neither the name of The NetBSD Foundation nor the names of its
  48  *    contributors may be used to endorse or promote products derived
  49  *    from this software without specific prior written permission.
  50  *
  51  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  52  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  53  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  54  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  55  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  56  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  57  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  58  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  59  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  60  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  61  * POSSIBILITY OF SUCH DAMAGE.
  62  *
  63  * $FreeBSD: src/sys/netinet/ip_flow.c,v 1.9.2.1 2001/08/08 08:20:35 ru Exp $
  64  */
  65
  66 #include <sys/param.h>
  67 #include <sys/systm.h>
  68 #include <sys/malloc.h>
  69 #include <sys/mbuf.h>
  70 #include <sys/protosw.h>
  71 #include <sys/socket.h>
  72 #include <sys/kernel.h>
  73
  74 #include <sys/sysctl.h>
  75 #include <libkern/OSAtomic.h>
  76
  77 #include <net/if.h>
  78 #include <net/route.h>
  79
  80 #include <netinet/in.h>
  81 #include <netinet/in_systm.h>
  82 #include <netinet/ip.h>
  83 #include <netinet/in_var.h>
  84 #include <netinet/ip_var.h>
  85 #include <netinet/ip_flow.h>
  86 #include <net/dlil.h>
  87
  88 #define IPFLOW_TIMER            (5 * PR_SLOWHZ)
  89 #define IPFLOW_HASHBITS         6       /* should not be a multiple of 8 */
  90 #define IPFLOW_HASHSIZE         (1 << IPFLOW_HASHBITS)
  91 static LIST_HEAD(ipflowhead, ipflow) ipflows[IPFLOW_HASHSIZE];
  92 static int ipflow_inuse;
  93 #define IPFLOW_MAX              256
  94
  95 #ifdef __APPLE__
  96 #define M_IPFLOW M_TEMP
  97 #endif
  98
  99 static int ipflow_active = 0;
 100 SYSCTL_INT(_net_inet_ip, IPCTL_FASTFORWARDING, fastforwarding, CTLFLAG_RW,
 101     &ipflow_active, 0, "Enable flow-based IP forwarding");
 102
 103 #ifndef __APPLE__
 104 static MALLOC_DEFINE(M_IPFLOW, "ip_flow", "IP flow");
 105 #endif
 106
 107 static unsigned
 108 ipflow_hash(
 109         struct in_addr dst,
 110         struct in_addr src,
 111         unsigned tos)
 112 {
 113         unsigned hash = tos;
 114         int idx;
 115         for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS)
 116                 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx);
 117         return hash & (IPFLOW_HASHSIZE-1);
 118 }
 119
 120 static struct ipflow *
 121 ipflow_lookup(
 122         const struct ip *ip)
 123 {
 124         unsigned hash;
 125         struct ipflow *ipf;
 126
 127         hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
 128
 129         ipf = LIST_FIRST(&ipflows[hash]);
 130         while (ipf != NULL) {
 131                 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
 132                     && ip->ip_src.s_addr == ipf->ipf_src.s_addr
 133                     && ip->ip_tos == ipf->ipf_tos)
 134                         break;
 135                 ipf = LIST_NEXT(ipf, ipf_next);
 136         }
 137         return ipf;
 138 }
 139
 140 int
 141 ipflow_fastforward(
 142         struct mbuf *m)
 143 {
 144         struct ip *ip;
 145         struct ipflow *ipf;
 146         struct rtentry *rt;
 147         struct sockaddr *dst;
 148         int error;
 149
 150         /*
 151          * Are we forwarding packets?  Big enough for an IP packet?
 152          */
 153         if (!ipforwarding || !ipflow_active || m->m_len < sizeof(struct ip))
 154                 return 0;
 155         /*
 156          * IP header with no option and valid version and length
 157          */
 158         ip = mtod(m, struct ip *);
 159         if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2)
 160             || ntohs(ip->ip_len) > m->m_pkthdr.len)
 161                 return 0;
 162         /*
 163          * Find a flow.
 164          */
 165         if ((ipf = ipflow_lookup(ip)) == NULL)
 166                 return 0;
 167
 168         /*
 169          * Route and interface still up?
 170          */
 171         rt = ipf->ipf_ro.ro_rt;
 172         if ((rt->rt_flags & RTF_UP) == 0 || (rt->rt_ifp->if_flags & IFF_UP) == 0)
 173                 return 0;
 174
 175         /*
 176          * Packet size OK?  TTL?
 177          */
 178         if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
 179                 return 0;
 180
 181         /*
 182          * Everything checks out and so we can forward this packet.
 183          * Modify the TTL and incrementally change the checksum.
 184          */
 185         ip->ip_ttl -= IPTTLDEC;
 186         if (ip->ip_sum >= htons(0xffff - (IPTTLDEC << 8))) {
 187                 ip->ip_sum += htons(IPTTLDEC << 8) + 1;
 188         } else {
 189                 ip->ip_sum += htons(IPTTLDEC << 8);
 190         }
 191
 192         /*
 193          * Send the packet on its way.  All we can get back is ENOBUFS
 194          */
 195         ipf->ipf_uses++;
 196         ipf->ipf_timer = IPFLOW_TIMER;
 197
 198         if (rt->rt_flags & RTF_GATEWAY)
 199                 dst = rt->rt_gateway;
 200         else
 201                 dst = &ipf->ipf_ro.ro_dst;
 202 #ifdef __APPLE__
 203         /* Not sure the rt_dlt is valid here !! XXX */
 204         if ((error = dlil_output(rt->rt_ifp, PF_INET, m, (caddr_t) rt, dst, 0)) != 0) {
 205
 206 #else
 207         if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
 208 #endif
 209                 if (error == ENOBUFS)
 210                         ipf->ipf_dropped++;
 211                 else
 212                         ipf->ipf_errors++;
 213         }
 214         return 1;
 215 }
 216 \f
 217 static void
 218 ipflow_addstats(
 219         struct ipflow *ipf)
 220 {
 221         ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
 222         OSAddAtomic(ipf->ipf_errors + ipf->ipf_dropped, (SInt32*)&ipstat.ips_cantforward);
 223         OSAddAtomic(ipf->ipf_uses, (SInt32*)&ipstat.ips_forward);
 224         OSAddAtomic(ipf->ipf_uses, (SInt32*)&ipstat.ips_fastforward);
 225 }
 226
 227 static void
 228 ipflow_free(
 229         struct ipflow *ipf)
 230 {
 231         /*
 232          * Remove the flow from the hash table (at elevated IPL).
 233          * Once it's off the list, we can deal with it at normal
 234          * network IPL.
 235          */
 236         LIST_REMOVE(ipf, ipf_next);
 237         ipflow_addstats(ipf);
 238         rtfree(ipf->ipf_ro.ro_rt);
 239         ipflow_inuse--;
 240         FREE(ipf, M_IPFLOW);
 241 }
 242
 243 static struct ipflow *
 244 ipflow_reap(
 245         void)
 246 {
 247         struct ipflow *ipf, *maybe_ipf = NULL;
 248         int idx;
 249
 250         for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) {
 251                 ipf = LIST_FIRST(&ipflows[idx]);
 252                 while (ipf != NULL) {
 253                         /*
 254                          * If this no longer points to a valid route
 255                          * reclaim it.
 256                          */
 257                         if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0)
 258                                 goto done;
 259                         /*
 260                          * choose the one that's been least recently used
 261                          * or has had the least uses in the last 1.5
 262                          * intervals.
 263                          */
 264                         if (maybe_ipf == NULL
 265                             || ipf->ipf_timer < maybe_ipf->ipf_timer
 266                             || (ipf->ipf_timer == maybe_ipf->ipf_timer
 267                                 && ipf->ipf_last_uses + ipf->ipf_uses <
 268                                       maybe_ipf->ipf_last_uses +
 269                                         maybe_ipf->ipf_uses))
 270                                 maybe_ipf = ipf;
 271                         ipf = LIST_NEXT(ipf, ipf_next);
 272                 }
 273         }
 274         ipf = maybe_ipf;
 275     done:
 276         /*
 277          * Remove the entry from the flow table.
 278          */
 279         LIST_REMOVE(ipf, ipf_next);
 280         ipflow_addstats(ipf);
 281         rtfree(ipf->ipf_ro.ro_rt);
 282         return ipf;
 283 }
 284 /* note: called under the ip_mutex lock */
 285 void
 286 ipflow_slowtimo(
 287         void)
 288 {
 289         struct ipflow *ipf;
 290         int idx;
 291
 292         for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) {
 293                 ipf = LIST_FIRST(&ipflows[idx]);
 294                 while (ipf != NULL) {
 295                         struct ipflow *next_ipf = LIST_NEXT(ipf, ipf_next);
 296                         if (--ipf->ipf_timer == 0) {
 297                                 ipflow_free(ipf);
 298                         } else {
 299                                 ipf->ipf_last_uses = ipf->ipf_uses;
 300                                 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
 301                                 OSAddAtomic(ipf->ipf_uses, (SInt32*)&ipstat.ips_forward);
 302                                 OSAddAtomic(ipf->ipf_uses, (SInt32*)&ipstat.ips_fastforward);
 303                                 ipstat.ips_forward += ipf->ipf_uses;
 304                                 ipstat.ips_fastforward += ipf->ipf_uses;
 305                                 ipf->ipf_uses = 0;
 306                         }
 307                         ipf = next_ipf;
 308                 }
 309         }
 310 }
 311
 312 void
 313 ipflow_create(
 314         const struct route *ro,
 315         struct mbuf *m)
 316 {
 317         const struct ip *const ip = mtod(m, struct ip *);
 318         struct ipflow *ipf;
 319         unsigned hash;
 320
 321         /*
 322          * Don't create cache entries for ICMP messages.
 323          */
 324         if (!ipflow_active || ip->ip_p == IPPROTO_ICMP)
 325                 return;
 326         /*
 327          * See if an existing flow struct exists.  If so remove it from it's
 328          * list and free the old route.  If not, try to malloc a new one
 329          * (if we aren't at our limit).
 330          */
 331         ipf = ipflow_lookup(ip);
 332         if (ipf == NULL) {
 333                 if (ipflow_inuse == IPFLOW_MAX) {
 334                         ipf = ipflow_reap();
 335                 } else {
 336                         ipf = (struct ipflow *) _MALLOC(sizeof(*ipf), M_IPFLOW,
 337                                                        M_NOWAIT);
 338                         if (ipf == NULL)
 339                                 return;
 340                         ipflow_inuse++;
 341                 }
 342                 bzero((caddr_t) ipf, sizeof(*ipf));
 343         } else {
 344                 LIST_REMOVE(ipf, ipf_next);
 345                 ipflow_addstats(ipf);
 346                 rtfree(ipf->ipf_ro.ro_rt);
 347                 ipf->ipf_uses = ipf->ipf_last_uses = 0;
 348                 ipf->ipf_errors = ipf->ipf_dropped = 0;
 349         }
 350
 351         /*
 352          * Fill in the updated information.
 353          */
 354         lck_mtx_lock(rt_mtx);
 355         ipf->ipf_ro = *ro;
 356         rtref(ro->ro_rt);
 357         lck_mtx_unlock(rt_mtx);
 358         ipf->ipf_dst = ip->ip_dst;
 359         ipf->ipf_src = ip->ip_src;
 360         ipf->ipf_tos = ip->ip_tos;
 361         ipf->ipf_timer = IPFLOW_TIMER;
 362         /*
 363          * Insert into the approriate bucket of the flow table.
 364          */
 365         hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
 366         LIST_INSERT_HEAD(&ipflows[hash], ipf, ipf_next);
 367 }