1 /* $NetBSD: ip_flow.c,v 1.66 2015/03/23 18:33:17 roy 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 1.66 2015/03/23 18:33:17 roy 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 static struct ipflowhead *ipflowtable = NULL; 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 static int ip_maxflows = IPFLOW_MAX; 95 static int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE; 96 97 static void ipflow_sysctl_init(struct sysctllog **); 98 99 static size_t 100 ipflow_hash(const struct ip *ip) 101 { 102 size_t hash = ip->ip_tos; 103 size_t idx; 104 105 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) { 106 hash += (ip->ip_dst.s_addr >> (32 - idx)) + 107 (ip->ip_src.s_addr >> idx); 108 } 109 110 return hash & (ip_hashsize-1); 111 } 112 113 static struct ipflow * 114 ipflow_lookup(const struct ip *ip) 115 { 116 size_t hash; 117 struct ipflow *ipf; 118 119 hash = ipflow_hash(ip); 120 121 LIST_FOREACH(ipf, &ipflowtable[hash], ipf_hash) { 122 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 123 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 124 && ip->ip_tos == ipf->ipf_tos) 125 break; 126 } 127 return ipf; 128 } 129 130 void 131 ipflow_poolinit(void) 132 { 133 134 pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", 135 NULL, IPL_NET); 136 } 137 138 static int 139 ipflow_reinit(int table_size) 140 { 141 struct ipflowhead *new_table; 142 size_t i; 143 144 new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) * 145 table_size, M_RTABLE, M_NOWAIT); 146 147 if (new_table == NULL) 148 return 1; 149 150 if (ipflowtable != NULL) 151 free(ipflowtable, M_RTABLE); 152 153 ipflowtable = new_table; 154 ip_hashsize = table_size; 155 156 LIST_INIT(&ipflowlist); 157 for (i = 0; i < ip_hashsize; i++) 158 LIST_INIT(&ipflowtable[i]); 159 160 return 0; 161 } 162 163 void 164 ipflow_init(void) 165 { 166 (void)ipflow_reinit(ip_hashsize); 167 ipflow_sysctl_init(NULL); 168 } 169 170 int 171 ipflow_fastforward(struct mbuf *m) 172 { 173 struct ip *ip; 174 struct ip ip_store; 175 struct ipflow *ipf; 176 struct rtentry *rt; 177 const struct sockaddr *dst; 178 int error; 179 int iplen; 180 181 /* 182 * Are we forwarding packets? Big enough for an IP packet? 183 */ 184 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip)) 185 return 0; 186 187 /* 188 * Was packet received as a link-level multicast or broadcast? 189 * If so, don't try to fast forward.. 190 */ 191 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0) 192 return 0; 193 194 /* 195 * IP header with no option and valid version and length 196 */ 197 if (IP_HDR_ALIGNED_P(mtod(m, const void *))) 198 ip = mtod(m, struct ip *); 199 else { 200 memcpy(&ip_store, mtod(m, const void *), sizeof(ip_store)); 201 ip = &ip_store; 202 } 203 iplen = ntohs(ip->ip_len); 204 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 205 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 206 return 0; 207 /* 208 * Find a flow. 209 */ 210 if ((ipf = ipflow_lookup(ip)) == NULL) 211 return 0; 212 213 /* 214 * Verify the IP header checksum. 215 */ 216 switch (m->m_pkthdr.csum_flags & 217 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) | 218 M_CSUM_IPv4_BAD)) { 219 case M_CSUM_IPv4|M_CSUM_IPv4_BAD: 220 return (0); 221 222 case M_CSUM_IPv4: 223 /* Checksum was okay. */ 224 break; 225 226 default: 227 /* Must compute it ourselves. */ 228 if (in_cksum(m, sizeof(struct ip)) != 0) 229 return (0); 230 break; 231 } 232 233 /* 234 * Route and interface still up? 235 */ 236 if ((rt = rtcache_validate(&ipf->ipf_ro)) == NULL || 237 (rt->rt_ifp->if_flags & IFF_UP) == 0 || 238 (rt->rt_flags & (RTF_BLACKHOLE | RTF_BROADCAST)) != 0) 239 return 0; 240 241 /* 242 * Packet size OK? TTL? 243 */ 244 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 245 return 0; 246 247 /* 248 * Clear any in-bound checksum flags for this packet. 249 */ 250 m->m_pkthdr.csum_flags = 0; 251 252 /* 253 * Everything checks out and so we can forward this packet. 254 * Modify the TTL and incrementally change the checksum. 255 * 256 * This method of adding the checksum works on either endian CPU. 257 * If htons() is inlined, all the arithmetic is folded; otherwise 258 * the htons()s are combined by CSE due to the const attribute. 259 * 260 * Don't bother using HW checksumming here -- the incremental 261 * update is pretty fast. 262 */ 263 ip->ip_ttl -= IPTTLDEC; 264 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 265 ip->ip_sum -= ~htons(IPTTLDEC << 8); 266 else 267 ip->ip_sum += htons(IPTTLDEC << 8); 268 269 /* 270 * Done modifying the header; copy it back, if necessary. 271 * 272 * XXX Use m_copyback_cow(9) here? --dyoung 273 */ 274 if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0) 275 memcpy(mtod(m, void *), &ip_store, sizeof(ip_store)); 276 277 /* 278 * Trim the packet in case it's too long.. 279 */ 280 if (m->m_pkthdr.len > iplen) { 281 if (m->m_len == m->m_pkthdr.len) { 282 m->m_len = iplen; 283 m->m_pkthdr.len = iplen; 284 } else 285 m_adj(m, iplen - m->m_pkthdr.len); 286 } 287 288 /* 289 * Send the packet on its way. All we can get back is ENOBUFS 290 */ 291 ipf->ipf_uses++; 292 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 293 294 if (rt->rt_flags & RTF_GATEWAY) 295 dst = rt->rt_gateway; 296 else 297 dst = rtcache_getdst(&ipf->ipf_ro); 298 299 KERNEL_LOCK(1, NULL); 300 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 301 if (error == ENOBUFS) 302 ipf->ipf_dropped++; 303 else 304 ipf->ipf_errors++; 305 } 306 KERNEL_UNLOCK_ONE(NULL); 307 return 1; 308 } 309 310 static void 311 ipflow_addstats(struct ipflow *ipf) 312 { 313 struct rtentry *rt; 314 uint64_t *ips; 315 316 if ((rt = rtcache_validate(&ipf->ipf_ro)) != NULL) 317 rt->rt_use += ipf->ipf_uses; 318 319 ips = IP_STAT_GETREF(); 320 ips[IP_STAT_CANTFORWARD] += ipf->ipf_errors + ipf->ipf_dropped; 321 ips[IP_STAT_TOTAL] += ipf->ipf_uses; 322 ips[IP_STAT_FORWARD] += ipf->ipf_uses; 323 ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses; 324 IP_STAT_PUTREF(); 325 } 326 327 static void 328 ipflow_free(struct ipflow *ipf) 329 { 330 int s; 331 /* 332 * Remove the flow from the hash table (at elevated IPL). 333 * Once it's off the list, we can deal with it at normal 334 * network IPL. 335 */ 336 s = splnet(); 337 IPFLOW_REMOVE(ipf); 338 splx(s); 339 ipflow_addstats(ipf); 340 rtcache_free(&ipf->ipf_ro); 341 ipflow_inuse--; 342 s = splnet(); 343 pool_put(&ipflow_pool, ipf); 344 splx(s); 345 } 346 347 struct ipflow * 348 ipflow_reap(bool just_one) 349 { 350 while (just_one || ipflow_inuse > ip_maxflows) { 351 struct ipflow *ipf, *maybe_ipf = NULL; 352 int s; 353 354 ipf = LIST_FIRST(&ipflowlist); 355 while (ipf != NULL) { 356 /* 357 * If this no longer points to a valid route 358 * reclaim it. 359 */ 360 if (rtcache_validate(&ipf->ipf_ro) == NULL) 361 goto done; 362 /* 363 * choose the one that's been least recently 364 * used or has had the least uses in the 365 * last 1.5 intervals. 366 */ 367 if (maybe_ipf == NULL || 368 ipf->ipf_timer < maybe_ipf->ipf_timer || 369 (ipf->ipf_timer == maybe_ipf->ipf_timer && 370 ipf->ipf_last_uses + ipf->ipf_uses < 371 maybe_ipf->ipf_last_uses + 372 maybe_ipf->ipf_uses)) 373 maybe_ipf = ipf; 374 ipf = LIST_NEXT(ipf, ipf_list); 375 } 376 ipf = maybe_ipf; 377 done: 378 /* 379 * Remove the entry from the flow table. 380 */ 381 s = splnet(); 382 IPFLOW_REMOVE(ipf); 383 splx(s); 384 ipflow_addstats(ipf); 385 rtcache_free(&ipf->ipf_ro); 386 if (just_one) 387 return ipf; 388 pool_put(&ipflow_pool, ipf); 389 ipflow_inuse--; 390 } 391 return NULL; 392 } 393 394 void 395 ipflow_slowtimo(void) 396 { 397 struct rtentry *rt; 398 struct ipflow *ipf, *next_ipf; 399 uint64_t *ips; 400 401 mutex_enter(softnet_lock); 402 KERNEL_LOCK(1, NULL); 403 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) { 404 next_ipf = LIST_NEXT(ipf, ipf_list); 405 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) || 406 (rt = rtcache_validate(&ipf->ipf_ro)) == NULL) { 407 ipflow_free(ipf); 408 } else { 409 ipf->ipf_last_uses = ipf->ipf_uses; 410 rt->rt_use += ipf->ipf_uses; 411 ips = IP_STAT_GETREF(); 412 ips[IP_STAT_TOTAL] += ipf->ipf_uses; 413 ips[IP_STAT_FORWARD] += ipf->ipf_uses; 414 ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses; 415 IP_STAT_PUTREF(); 416 ipf->ipf_uses = 0; 417 } 418 } 419 KERNEL_UNLOCK_ONE(NULL); 420 mutex_exit(softnet_lock); 421 } 422 423 void 424 ipflow_create(const struct route *ro, struct mbuf *m) 425 { 426 const struct ip *const ip = mtod(m, const struct ip *); 427 struct ipflow *ipf; 428 size_t hash; 429 int s; 430 431 /* 432 * Don't create cache entries for ICMP messages. 433 */ 434 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 435 return; 436 437 KERNEL_LOCK(1, NULL); 438 439 /* 440 * See if an existing flow struct exists. If so remove it from its 441 * list and free the old route. If not, try to malloc a new one 442 * (if we aren't at our limit). 443 */ 444 ipf = ipflow_lookup(ip); 445 if (ipf == NULL) { 446 if (ipflow_inuse >= ip_maxflows) { 447 ipf = ipflow_reap(true); 448 } else { 449 s = splnet(); 450 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 451 splx(s); 452 if (ipf == NULL) 453 goto out; 454 ipflow_inuse++; 455 } 456 memset(ipf, 0, sizeof(*ipf)); 457 } else { 458 s = splnet(); 459 IPFLOW_REMOVE(ipf); 460 splx(s); 461 ipflow_addstats(ipf); 462 rtcache_free(&ipf->ipf_ro); 463 ipf->ipf_uses = ipf->ipf_last_uses = 0; 464 ipf->ipf_errors = ipf->ipf_dropped = 0; 465 } 466 467 /* 468 * Fill in the updated information. 469 */ 470 rtcache_copy(&ipf->ipf_ro, ro); 471 ipf->ipf_dst = ip->ip_dst; 472 ipf->ipf_src = ip->ip_src; 473 ipf->ipf_tos = ip->ip_tos; 474 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 475 476 /* 477 * Insert into the approriate bucket of the flow table. 478 */ 479 hash = ipflow_hash(ip); 480 s = splnet(); 481 IPFLOW_INSERT(&ipflowtable[hash], ipf); 482 splx(s); 483 484 out: 485 KERNEL_UNLOCK_ONE(NULL); 486 } 487 488 int 489 ipflow_invalidate_all(int new_size) 490 { 491 struct ipflow *ipf, *next_ipf; 492 int s, error; 493 494 error = 0; 495 s = splnet(); 496 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) { 497 next_ipf = LIST_NEXT(ipf, ipf_list); 498 ipflow_free(ipf); 499 } 500 501 if (new_size) 502 error = ipflow_reinit(new_size); 503 splx(s); 504 505 return error; 506 } 507 508 #ifdef GATEWAY 509 /* 510 * sysctl helper routine for net.inet.ip.maxflows. 511 */ 512 static int 513 sysctl_net_inet_ip_maxflows(SYSCTLFN_ARGS) 514 { 515 int error; 516 517 error = sysctl_lookup(SYSCTLFN_CALL(rnode)); 518 if (error || newp == NULL) 519 return (error); 520 521 mutex_enter(softnet_lock); 522 KERNEL_LOCK(1, NULL); 523 524 ipflow_reap(false); 525 526 KERNEL_UNLOCK_ONE(NULL); 527 mutex_exit(softnet_lock); 528 529 return (0); 530 } 531 532 static int 533 sysctl_net_inet_ip_hashsize(SYSCTLFN_ARGS) 534 { 535 int error, tmp; 536 struct sysctlnode node; 537 538 node = *rnode; 539 tmp = ip_hashsize; 540 node.sysctl_data = &tmp; 541 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 542 if (error || newp == NULL) 543 return (error); 544 545 if ((tmp & (tmp - 1)) == 0 && tmp != 0) { 546 /* 547 * Can only fail due to malloc() 548 */ 549 mutex_enter(softnet_lock); 550 KERNEL_LOCK(1, NULL); 551 552 error = ipflow_invalidate_all(tmp); 553 554 KERNEL_UNLOCK_ONE(NULL); 555 mutex_exit(softnet_lock); 556 557 } else { 558 /* 559 * EINVAL if not a power of 2 560 */ 561 error = EINVAL; 562 } 563 564 return error; 565 } 566 #endif /* GATEWAY */ 567 568 static void 569 ipflow_sysctl_init(struct sysctllog **clog) 570 { 571 sysctl_createv(clog, 0, NULL, NULL, 572 CTLFLAG_PERMANENT, 573 CTLTYPE_NODE, "inet", 574 SYSCTL_DESCR("PF_INET related settings"), 575 NULL, 0, NULL, 0, 576 CTL_NET, PF_INET, CTL_EOL); 577 sysctl_createv(clog, 0, NULL, NULL, 578 CTLFLAG_PERMANENT, 579 CTLTYPE_NODE, "ip", 580 SYSCTL_DESCR("IPv4 related settings"), 581 NULL, 0, NULL, 0, 582 CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL); 583 584 #ifdef GATEWAY 585 sysctl_createv(clog, 0, NULL, NULL, 586 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 587 CTLTYPE_INT, "maxflows", 588 SYSCTL_DESCR("Number of flows for fast forwarding"), 589 sysctl_net_inet_ip_maxflows, 0, &ip_maxflows, 0, 590 CTL_NET, PF_INET, IPPROTO_IP, 591 IPCTL_MAXFLOWS, CTL_EOL); 592 sysctl_createv(clog, 0, NULL, NULL, 593 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 594 CTLTYPE_INT, "hashsize", 595 SYSCTL_DESCR("Size of hash table for fast forwarding (IPv4)"), 596 sysctl_net_inet_ip_hashsize, 0, &ip_hashsize, 0, 597 CTL_NET, PF_INET, IPPROTO_IP, 598 CTL_CREATE, CTL_EOL); 599 #endif /* GATEWAY */ 600 } 601