ip_flow.c revision 1.27
1 /* $NetBSD: ip_flow.c,v 1.27 2003/12/12 21:17:59 scw 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 1.27 2003/12/12 21:17:59 scw 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 struct pool ipflow_pool; 69 70 LIST_HEAD(ipflowhead, ipflow); 71 72 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 73 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 74 75 static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE]; 76 static struct ipflowhead ipflowlist; 77 static int ipflow_inuse; 78 79 #define IPFLOW_INSERT(bucket, ipf) \ 80 do { \ 81 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \ 82 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \ 83 } while (/*CONSTCOND*/ 0) 84 85 #define IPFLOW_REMOVE(ipf) \ 86 do { \ 87 LIST_REMOVE((ipf), ipf_hash); \ 88 LIST_REMOVE((ipf), ipf_list); \ 89 } while (/*CONSTCOND*/ 0) 90 91 #ifndef IPFLOW_MAX 92 #define IPFLOW_MAX 256 93 #endif 94 int ip_maxflows = IPFLOW_MAX; 95 96 static unsigned 97 ipflow_hash( 98 struct in_addr dst, 99 struct in_addr src, 100 unsigned tos) 101 { 102 unsigned hash = tos; 103 int idx; 104 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 105 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 106 return hash & (IPFLOW_HASHSIZE-1); 107 } 108 109 static struct ipflow * 110 ipflow_lookup( 111 const struct ip *ip) 112 { 113 unsigned hash; 114 struct ipflow *ipf; 115 116 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 117 118 ipf = LIST_FIRST(&ipflowtable[hash]); 119 while (ipf != NULL) { 120 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 121 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 122 && ip->ip_tos == ipf->ipf_tos) 123 break; 124 ipf = LIST_NEXT(ipf, ipf_hash); 125 } 126 return ipf; 127 } 128 129 void 130 ipflow_init() 131 { 132 int i; 133 134 pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", 135 NULL); 136 137 LIST_INIT(&ipflowlist); 138 for (i = 0; i < IPFLOW_HASHSIZE; i++) 139 LIST_INIT(&ipflowtable[i]); 140 } 141 142 int 143 ipflow_fastforward( 144 struct mbuf *m) 145 { 146 struct ip *ip, ip_store; 147 struct ipflow *ipf; 148 struct rtentry *rt; 149 struct sockaddr *dst; 150 int error; 151 int iplen; 152 153 /* 154 * Are we forwarding packets? Big enough for an IP packet? 155 */ 156 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip)) 157 return 0; 158 159 /* 160 * Was packet received as a link-level multicast or broadcast? 161 * If so, don't try to fast forward.. 162 */ 163 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0) 164 return 0; 165 166 /* 167 * IP header with no option and valid version and length 168 */ 169 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t))) 170 ip = mtod(m, struct ip *); 171 else { 172 memcpy(&ip_store, mtod(m, caddr_t), sizeof(ip_store)); 173 ip = &ip_store; 174 } 175 iplen = ntohs(ip->ip_len); 176 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 177 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 178 return 0; 179 /* 180 * Find a flow. 181 */ 182 if ((ipf = ipflow_lookup(ip)) == NULL) 183 return 0; 184 185 /* 186 * Verify the IP header checksum. 187 */ 188 switch (m->m_pkthdr.csum_flags & 189 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) | 190 M_CSUM_IPv4_BAD)) { 191 case M_CSUM_IPv4|M_CSUM_IPv4_BAD: 192 return (0); 193 194 case M_CSUM_IPv4: 195 /* Checksum was okay. */ 196 break; 197 198 default: 199 /* Must compute it ourselves. */ 200 if (in_cksum(m, sizeof(struct ip)) != 0) 201 return (0); 202 break; 203 } 204 205 /* 206 * Route and interface still up? 207 */ 208 rt = ipf->ipf_ro.ro_rt; 209 if ((rt->rt_flags & RTF_UP) == 0 || 210 (rt->rt_ifp->if_flags & IFF_UP) == 0) 211 return 0; 212 213 /* 214 * Packet size OK? TTL? 215 */ 216 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 217 return 0; 218 219 /* 220 * Clear any in-bound checksum flags for this packet. 221 */ 222 m->m_pkthdr.csum_flags = 0; 223 224 /* 225 * Everything checks out and so we can forward this packet. 226 * Modify the TTL and incrementally change the checksum. 227 * 228 * This method of adding the checksum works on either endian CPU. 229 * If htons() is inlined, all the arithmetic is folded; otherwise 230 * the htons()s are combined by CSE due to the __const__ attribute. 231 * 232 * Don't bother using HW checksumming here -- the incremental 233 * update is pretty fast. 234 */ 235 ip->ip_ttl -= IPTTLDEC; 236 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 237 ip->ip_sum -= ~htons(IPTTLDEC << 8); 238 else 239 ip->ip_sum += htons(IPTTLDEC << 8); 240 241 /* 242 * Done modifying the header; copy it back, if necessary. 243 */ 244 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0) 245 memcpy(mtod(m, caddr_t), &ip_store, sizeof(ip_store)); 246 247 /* 248 * Trim the packet in case it's too long.. 249 */ 250 if (m->m_pkthdr.len > iplen) { 251 if (m->m_len == m->m_pkthdr.len) { 252 m->m_len = iplen; 253 m->m_pkthdr.len = iplen; 254 } else 255 m_adj(m, iplen - m->m_pkthdr.len); 256 } 257 258 /* 259 * Send the packet on it's way. All we can get back is ENOBUFS 260 */ 261 ipf->ipf_uses++; 262 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 263 264 if (rt->rt_flags & RTF_GATEWAY) 265 dst = rt->rt_gateway; 266 else 267 dst = &ipf->ipf_ro.ro_dst; 268 269 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 270 if (error == ENOBUFS) 271 ipf->ipf_dropped++; 272 else 273 ipf->ipf_errors++; 274 } 275 return 1; 276 } 277 278 static void 280 ipflow_addstats( 281 struct ipflow *ipf) 282 { 283 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 284 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 285 ipstat.ips_forward += ipf->ipf_uses; 286 ipstat.ips_fastforward += ipf->ipf_uses; 287 } 288 289 static void 290 ipflow_free( 291 struct ipflow *ipf) 292 { 293 int s; 294 /* 295 * Remove the flow from the hash table (at elevated IPL). 296 * Once it's off the list, we can deal with it at normal 297 * network IPL. 298 */ 299 s = splnet(); 300 IPFLOW_REMOVE(ipf); 301 splx(s); 302 ipflow_addstats(ipf); 303 RTFREE(ipf->ipf_ro.ro_rt); 304 ipflow_inuse--; 305 pool_put(&ipflow_pool, ipf); 306 } 307 308 struct ipflow * 309 ipflow_reap( 310 int just_one) 311 { 312 while (just_one || ipflow_inuse > ip_maxflows) { 313 struct ipflow *ipf, *maybe_ipf = NULL; 314 int s; 315 316 ipf = LIST_FIRST(&ipflowlist); 317 while (ipf != NULL) { 318 /* 319 * If this no longer points to a valid route 320 * reclaim it. 321 */ 322 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 323 goto done; 324 /* 325 * choose the one that's been least recently 326 * used or has had the least uses in the 327 * last 1.5 intervals. 328 */ 329 if (maybe_ipf == NULL || 330 ipf->ipf_timer < maybe_ipf->ipf_timer || 331 (ipf->ipf_timer == maybe_ipf->ipf_timer && 332 ipf->ipf_last_uses + ipf->ipf_uses < 333 maybe_ipf->ipf_last_uses + 334 maybe_ipf->ipf_uses)) 335 maybe_ipf = ipf; 336 ipf = LIST_NEXT(ipf, ipf_list); 337 } 338 ipf = maybe_ipf; 339 done: 340 /* 341 * Remove the entry from the flow table. 342 */ 343 s = splnet(); 344 IPFLOW_REMOVE(ipf); 345 splx(s); 346 ipflow_addstats(ipf); 347 RTFREE(ipf->ipf_ro.ro_rt); 348 if (just_one) 349 return ipf; 350 pool_put(&ipflow_pool, ipf); 351 ipflow_inuse--; 352 } 353 return NULL; 354 } 355 356 void 357 ipflow_slowtimo( 358 void) 359 { 360 struct ipflow *ipf, *next_ipf; 361 362 ipf = LIST_FIRST(&ipflowlist); 363 while (ipf != NULL) { 364 next_ipf = LIST_NEXT(ipf, ipf_list); 365 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 366 ipflow_free(ipf); 367 } else { 368 ipf->ipf_last_uses = ipf->ipf_uses; 369 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 370 ipstat.ips_forward += ipf->ipf_uses; 371 ipstat.ips_fastforward += ipf->ipf_uses; 372 ipf->ipf_uses = 0; 373 } 374 ipf = next_ipf; 375 } 376 } 377 378 void 379 ipflow_create( 380 const struct route *ro, 381 struct mbuf *m) 382 { 383 const struct ip *const ip = mtod(m, struct ip *); 384 struct ipflow *ipf; 385 unsigned hash; 386 int s; 387 388 /* 389 * Don't create cache entries for ICMP messages. 390 */ 391 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 392 return; 393 /* 394 * See if an existing flow struct exists. If so remove it from it's 395 * list and free the old route. If not, try to malloc a new one 396 * (if we aren't at our limit). 397 */ 398 ipf = ipflow_lookup(ip); 399 if (ipf == NULL) { 400 if (ipflow_inuse >= ip_maxflows) { 401 ipf = ipflow_reap(1); 402 } else { 403 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 404 if (ipf == NULL) 405 return; 406 ipflow_inuse++; 407 } 408 bzero((caddr_t) ipf, sizeof(*ipf)); 409 } else { 410 s = splnet(); 411 IPFLOW_REMOVE(ipf); 412 splx(s); 413 ipflow_addstats(ipf); 414 RTFREE(ipf->ipf_ro.ro_rt); 415 ipf->ipf_uses = ipf->ipf_last_uses = 0; 416 ipf->ipf_errors = ipf->ipf_dropped = 0; 417 } 418 419 /* 420 * Fill in the updated information. 421 */ 422 ipf->ipf_ro = *ro; 423 ro->ro_rt->rt_refcnt++; 424 ipf->ipf_dst = ip->ip_dst; 425 ipf->ipf_src = ip->ip_src; 426 ipf->ipf_tos = ip->ip_tos; 427 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 428 ipf->ipf_start = time.tv_sec; 429 /* 430 * Insert into the approriate bucket of the flow table. 431 */ 432 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 433 s = splnet(); 434 IPFLOW_INSERT(&ipflowtable[hash], ipf); 435 splx(s); 436 } 437 438 void 439 ipflow_invalidate_all( 440 void) 441 { 442 struct ipflow *ipf, *next_ipf; 443 int s; 444 445 s = splnet(); 446 ipf = LIST_FIRST(&ipflowlist); 447 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) { 448 next_ipf = LIST_NEXT(ipf, ipf_list); 449 ipflow_free(ipf); 450 } 451 splx(s); 452 } 453
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