1 /*- 2 * Copyright (c) 1998 The NetBSD Foundation, Inc. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to The NetBSD Foundation 6 * by the 3am Software Foundry ("3am"). It was developed by Matt Thomas. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the NetBSD 19 * Foundation, Inc. and its contributors. 20 * 4. Neither the name of The NetBSD Foundation nor the names of its 21 * contributors may be used to endorse or promote products derived 22 * from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 25 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 26 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 27 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 28 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 * POSSIBILITY OF SUCH DAMAGE. 35 * 36 * $FreeBSD: src/sys/netinet/ip_flow.c,v 1.9.2.2 2001/11/04 17:35:31 luigi Exp $ 37 * $DragonFly: src/sys/netinet/ip_flow.c,v 1.10 2006/09/05 00:55:48 dillon Exp $ 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/malloc.h> 43 #include <sys/mbuf.h> 44 #include <sys/globaldata.h> 45 #include <sys/thread.h> 46 #include <sys/protosw.h> 47 #include <sys/socket.h> 48 #include <sys/kernel.h> 49 50 #include <sys/sysctl.h> 51 #include <sys/thread2.h> 52 53 #include <net/if.h> 54 #include <net/route.h> 55 56 #include <netinet/in.h> 57 #include <netinet/in_systm.h> 58 #include <netinet/ip.h> 59 #include <netinet/in_var.h> 60 #include <netinet/ip_var.h> 61 #include <netinet/ip_flow.h> 62 63 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 64 #define IPFLOW_HASHBITS 6 /* should not be a multiple of 8 */ 65 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 66 static LIST_HEAD(ipflowhead, ipflow) ipflows[IPFLOW_HASHSIZE]; 67 static int ipflow_inuse; 68 #define IPFLOW_MAX 256 69 70 static int ipflow_active = 0; 71 SYSCTL_INT(_net_inet_ip, IPCTL_FASTFORWARDING, fastforwarding, CTLFLAG_RW, 72 &ipflow_active, 0, "Enable flow-based IP forwarding"); 73 74 static MALLOC_DEFINE(M_IPFLOW, "ip_flow", "IP flow"); 75 76 static unsigned 77 ipflow_hash(struct in_addr dst, struct in_addr src, unsigned tos) 78 { 79 unsigned hash = tos; 80 int idx; 81 82 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 83 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 84 return hash & (IPFLOW_HASHSIZE-1); 85 } 86 87 static struct ipflow * 88 ipflow_lookup(const struct ip *ip) 89 { 90 unsigned hash; 91 struct ipflow *ipf; 92 93 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 94 95 ipf = LIST_FIRST(&ipflows[hash]); 96 while (ipf != NULL) { 97 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr && 98 ip->ip_src.s_addr == ipf->ipf_src.s_addr && 99 ip->ip_tos == ipf->ipf_tos) 100 break; 101 ipf = LIST_NEXT(ipf, ipf_next); 102 } 103 return ipf; 104 } 105 106 int 107 ipflow_fastforward(struct mbuf *m, lwkt_serialize_t serializer) 108 { 109 struct ip *ip; 110 struct ipflow *ipf; 111 struct rtentry *rt; 112 struct sockaddr *dst; 113 int error; 114 115 /* 116 * Are we forwarding packets? Big enough for an IP packet? 117 */ 118 if (!ipforwarding || !ipflow_active || m->m_len < sizeof(struct ip)) 119 return 0; 120 /* 121 * IP header with no option and valid version and length 122 */ 123 ip = mtod(m, struct ip *); 124 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 125 ntohs(ip->ip_len) > m->m_pkthdr.len) 126 return 0; 127 /* 128 * Find a flow. 129 */ 130 if ((ipf = ipflow_lookup(ip)) == NULL) 131 return 0; 132 133 /* 134 * Route and interface still up? 135 */ 136 rt = ipf->ipf_ro.ro_rt; 137 if ((rt->rt_flags & RTF_UP) == 0 || (rt->rt_ifp->if_flags & IFF_UP) == 0) 138 return 0; 139 140 /* 141 * Packet size OK? TTL? 142 */ 143 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 144 return 0; 145 146 /* 147 * Everything checks out and so we can forward this packet. 148 * Modify the TTL and incrementally change the checksum. 149 */ 150 ip->ip_ttl -= IPTTLDEC; 151 if (ip->ip_sum >= htons(0xffff - (IPTTLDEC << 8))) 152 ip->ip_sum += htons(IPTTLDEC << 8) + 1; 153 else 154 ip->ip_sum += htons(IPTTLDEC << 8); 155 156 /* 157 * Send the packet on its way. All we can get back is ENOBUFS 158 */ 159 ipf->ipf_uses++; 160 ipf->ipf_timer = IPFLOW_TIMER; 161 162 if (rt->rt_flags & RTF_GATEWAY) 163 dst = rt->rt_gateway; 164 else 165 dst = &ipf->ipf_ro.ro_dst; 166 if (serializer) 167 lwkt_serialize_exit(serializer); 168 lwkt_serialize_enter(rt->rt_ifp->if_serializer); 169 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 170 if (error == ENOBUFS) 171 ipf->ipf_dropped++; 172 else 173 ipf->ipf_errors++; 174 } 175 lwkt_serialize_exit(rt->rt_ifp->if_serializer); 176 if (serializer) 177 lwkt_serialize_enter(serializer); 178 return 1; 179 } 180 181 static void 182 ipflow_addstats(struct ipflow *ipf) 183 { 184 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 185 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 186 ipstat.ips_forward += ipf->ipf_uses; 187 ipstat.ips_fastforward += ipf->ipf_uses; 188 } 189 190 static void 191 ipflow_free(struct ipflow *ipf) 192 { 193 /* 194 * Remove the flow from the hash table (at elevated IPL). 195 * Once it's off the list, we can deal with it at normal 196 * network IPL. 197 */ 198 crit_enter(); 199 LIST_REMOVE(ipf, ipf_next); 200 crit_exit(); 201 ipflow_addstats(ipf); 202 RTFREE(ipf->ipf_ro.ro_rt); 203 ipflow_inuse--; 204 kfree(ipf, M_IPFLOW); 205 } 206 207 static struct ipflow * 208 ipflow_reap(void) 209 { 210 struct ipflow *ipf, *maybe_ipf = NULL; 211 int idx; 212 213 for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) { 214 ipf = LIST_FIRST(&ipflows[idx]); 215 while (ipf != NULL) { 216 /* 217 * If this no longer points to a valid route 218 * reclaim it. 219 */ 220 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 221 goto done; 222 /* 223 * choose the one that's been least recently used 224 * or has had the least uses in the last 1.5 225 * intervals. 226 */ 227 if (maybe_ipf == NULL || 228 ipf->ipf_timer < maybe_ipf->ipf_timer || 229 (ipf->ipf_timer == maybe_ipf->ipf_timer && 230 ipf->ipf_last_uses + ipf->ipf_uses < 231 maybe_ipf->ipf_last_uses + maybe_ipf->ipf_uses)) 232 maybe_ipf = ipf; 233 ipf = LIST_NEXT(ipf, ipf_next); 234 } 235 } 236 ipf = maybe_ipf; 237 done: 238 /* 239 * Remove the entry from the flow table. 240 */ 241 crit_enter(); 242 LIST_REMOVE(ipf, ipf_next); 243 crit_exit(); 244 ipflow_addstats(ipf); 245 RTFREE(ipf->ipf_ro.ro_rt); 246 return ipf; 247 } 248 249 void 250 ipflow_slowtimo(void) 251 { 252 struct ipflow *ipf; 253 int idx; 254 255 for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) { 256 ipf = LIST_FIRST(&ipflows[idx]); 257 while (ipf != NULL) { 258 struct ipflow *next_ipf = LIST_NEXT(ipf, ipf_next); 259 if (--ipf->ipf_timer == 0) { 260 ipflow_free(ipf); 261 } else { 262 ipf->ipf_last_uses = ipf->ipf_uses; 263 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 264 ipstat.ips_forward += ipf->ipf_uses; 265 ipstat.ips_fastforward += ipf->ipf_uses; 266 ipf->ipf_uses = 0; 267 } 268 ipf = next_ipf; 269 } 270 } 271 } 272 273 void 274 ipflow_create(const struct route *ro, struct mbuf *m) 275 { 276 const struct ip *const ip = mtod(m, struct ip *); 277 struct ipflow *ipf; 278 unsigned hash; 279 280 /* 281 * Don't create cache entries for ICMP messages. 282 */ 283 if (!ipflow_active || ip->ip_p == IPPROTO_ICMP) 284 return; 285 /* 286 * See if an existing flow struct exists. If so remove it from it's 287 * list and free the old route. If not, try to malloc a new one 288 * (if we aren't at our limit). 289 */ 290 ipf = ipflow_lookup(ip); 291 if (ipf == NULL) { 292 if (ipflow_inuse == IPFLOW_MAX) { 293 ipf = ipflow_reap(); 294 } else { 295 ipf = kmalloc(sizeof *ipf, M_IPFLOW, 296 M_INTWAIT | M_NULLOK); 297 if (ipf == NULL) 298 return; 299 ipflow_inuse++; 300 } 301 bzero(ipf, sizeof *ipf); 302 } else { 303 crit_enter(); 304 LIST_REMOVE(ipf, ipf_next); 305 crit_exit(); 306 ipflow_addstats(ipf); 307 RTFREE(ipf->ipf_ro.ro_rt); 308 ipf->ipf_uses = ipf->ipf_last_uses = 0; 309 ipf->ipf_errors = ipf->ipf_dropped = 0; 310 } 311 312 /* 313 * Fill in the updated information. 314 */ 315 ipf->ipf_ro = *ro; 316 ro->ro_rt->rt_refcnt++; 317 ipf->ipf_dst = ip->ip_dst; 318 ipf->ipf_src = ip->ip_src; 319 ipf->ipf_tos = ip->ip_tos; 320 ipf->ipf_timer = IPFLOW_TIMER; 321 /* 322 * Insert into the approriate bucket of the flow table. 323 */ 324 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 325 crit_enter(); 326 LIST_INSERT_HEAD(&ipflows[hash], ipf, ipf_next); 327 crit_exit(); 328 } 329