1 /* 2 * ip_vs_proto_udp.c: UDP load balancing support for IPVS 3 * 4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> 5 * Julian Anastasov <ja@ssi.bg> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * Changes: Hans Schillstrom <hans.schillstrom@ericsson.com> 13 * Network name space (netns) aware. 14 * 15 */ 16 17 #define KMSG_COMPONENT "IPVS" 18 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 19 20 #include <linux/in.h> 21 #include <linux/ip.h> 22 #include <linux/kernel.h> 23 #include <linux/netfilter.h> 24 #include <linux/netfilter_ipv4.h> 25 #include <linux/udp.h> 26 27 #include <net/ip_vs.h> 28 #include <net/ip.h> 29 #include <net/ip6_checksum.h> 30 31 static int 32 udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb, 33 struct ip_vs_proto_data *pd, 34 int *verdict, struct ip_vs_conn **cpp, 35 struct ip_vs_iphdr *iph) 36 { 37 struct ip_vs_service *svc; 38 struct udphdr _udph, *uh; 39 __be16 _ports[2], *ports = NULL; 40 41 if (likely(!ip_vs_iph_icmp(iph))) { 42 /* IPv6 fragments, only first fragment will hit this */ 43 uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph); 44 if (uh) 45 ports = &uh->source; 46 } else { 47 ports = skb_header_pointer( 48 skb, iph->len, sizeof(_ports), &_ports); 49 } 50 51 if (!ports) { 52 *verdict = NF_DROP; 53 return 0; 54 } 55 56 if (likely(!ip_vs_iph_inverse(iph))) 57 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol, 58 &iph->daddr, ports[1]); 59 else 60 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol, 61 &iph->saddr, ports[0]); 62 63 if (svc) { 64 int ignored; 65 66 if (ip_vs_todrop(ipvs)) { 67 /* 68 * It seems that we are very loaded. 69 * We have to drop this packet :( 70 */ 71 *verdict = NF_DROP; 72 return 0; 73 } 74 75 /* 76 * Let the virtual server select a real server for the 77 * incoming connection, and create a connection entry. 78 */ 79 *cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph); 80 if (!*cpp && ignored <= 0) { 81 if (!ignored) 82 *verdict = ip_vs_leave(svc, skb, pd, iph); 83 else 84 *verdict = NF_DROP; 85 return 0; 86 } 87 } 88 /* NF_ACCEPT */ 89 return 1; 90 } 91 92 93 static inline void 94 udp_fast_csum_update(int af, struct udphdr *uhdr, 95 const union nf_inet_addr *oldip, 96 const union nf_inet_addr *newip, 97 __be16 oldport, __be16 newport) 98 { 99 #ifdef CONFIG_IP_VS_IPV6 100 if (af == AF_INET6) 101 uhdr->check = 102 csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6, 103 ip_vs_check_diff2(oldport, newport, 104 ~csum_unfold(uhdr->check)))); 105 else 106 #endif 107 uhdr->check = 108 csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip, 109 ip_vs_check_diff2(oldport, newport, 110 ~csum_unfold(uhdr->check)))); 111 if (!uhdr->check) 112 uhdr->check = CSUM_MANGLED_0; 113 } 114 115 static inline void 116 udp_partial_csum_update(int af, struct udphdr *uhdr, 117 const union nf_inet_addr *oldip, 118 const union nf_inet_addr *newip, 119 __be16 oldlen, __be16 newlen) 120 { 121 #ifdef CONFIG_IP_VS_IPV6 122 if (af == AF_INET6) 123 uhdr->check = 124 ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6, 125 ip_vs_check_diff2(oldlen, newlen, 126 csum_unfold(uhdr->check)))); 127 else 128 #endif 129 uhdr->check = 130 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip, 131 ip_vs_check_diff2(oldlen, newlen, 132 csum_unfold(uhdr->check)))); 133 } 134 135 136 static int 137 udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, 138 struct ip_vs_conn *cp, struct ip_vs_iphdr *iph) 139 { 140 struct udphdr *udph; 141 unsigned int udphoff = iph->len; 142 int oldlen; 143 int payload_csum = 0; 144 145 #ifdef CONFIG_IP_VS_IPV6 146 if (cp->af == AF_INET6 && iph->fragoffs) 147 return 1; 148 #endif 149 oldlen = skb->len - udphoff; 150 151 /* csum_check requires unshared skb */ 152 if (!skb_make_writable(skb, udphoff+sizeof(*udph))) 153 return 0; 154 155 if (unlikely(cp->app != NULL)) { 156 int ret; 157 158 /* Some checks before mangling */ 159 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp)) 160 return 0; 161 162 /* 163 * Call application helper if needed 164 */ 165 if (!(ret = ip_vs_app_pkt_out(cp, skb))) 166 return 0; 167 /* ret=2: csum update is needed after payload mangling */ 168 if (ret == 1) 169 oldlen = skb->len - udphoff; 170 else 171 payload_csum = 1; 172 } 173 174 udph = (void *)skb_network_header(skb) + udphoff; 175 udph->source = cp->vport; 176 177 /* 178 * Adjust UDP checksums 179 */ 180 if (skb->ip_summed == CHECKSUM_PARTIAL) { 181 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr, 182 htons(oldlen), 183 htons(skb->len - udphoff)); 184 } else if (!payload_csum && (udph->check != 0)) { 185 /* Only port and addr are changed, do fast csum update */ 186 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr, 187 cp->dport, cp->vport); 188 if (skb->ip_summed == CHECKSUM_COMPLETE) 189 skb->ip_summed = (cp->app && pp->csum_check) ? 190 CHECKSUM_UNNECESSARY : CHECKSUM_NONE; 191 } else { 192 /* full checksum calculation */ 193 udph->check = 0; 194 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0); 195 #ifdef CONFIG_IP_VS_IPV6 196 if (cp->af == AF_INET6) 197 udph->check = csum_ipv6_magic(&cp->vaddr.in6, 198 &cp->caddr.in6, 199 skb->len - udphoff, 200 cp->protocol, skb->csum); 201 else 202 #endif 203 udph->check = csum_tcpudp_magic(cp->vaddr.ip, 204 cp->caddr.ip, 205 skb->len - udphoff, 206 cp->protocol, 207 skb->csum); 208 if (udph->check == 0) 209 udph->check = CSUM_MANGLED_0; 210 skb->ip_summed = CHECKSUM_UNNECESSARY; 211 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n", 212 pp->name, udph->check, 213 (char*)&(udph->check) - (char*)udph); 214 } 215 return 1; 216 } 217 218 219 static int 220 udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, 221 struct ip_vs_conn *cp, struct ip_vs_iphdr *iph) 222 { 223 struct udphdr *udph; 224 unsigned int udphoff = iph->len; 225 int oldlen; 226 int payload_csum = 0; 227 228 #ifdef CONFIG_IP_VS_IPV6 229 if (cp->af == AF_INET6 && iph->fragoffs) 230 return 1; 231 #endif 232 oldlen = skb->len - udphoff; 233 234 /* csum_check requires unshared skb */ 235 if (!skb_make_writable(skb, udphoff+sizeof(*udph))) 236 return 0; 237 238 if (unlikely(cp->app != NULL)) { 239 int ret; 240 241 /* Some checks before mangling */ 242 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp)) 243 return 0; 244 245 /* 246 * Attempt ip_vs_app call. 247 * It will fix ip_vs_conn 248 */ 249 if (!(ret = ip_vs_app_pkt_in(cp, skb))) 250 return 0; 251 /* ret=2: csum update is needed after payload mangling */ 252 if (ret == 1) 253 oldlen = skb->len - udphoff; 254 else 255 payload_csum = 1; 256 } 257 258 udph = (void *)skb_network_header(skb) + udphoff; 259 udph->dest = cp->dport; 260 261 /* 262 * Adjust UDP checksums 263 */ 264 if (skb->ip_summed == CHECKSUM_PARTIAL) { 265 udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr, 266 htons(oldlen), 267 htons(skb->len - udphoff)); 268 } else if (!payload_csum && (udph->check != 0)) { 269 /* Only port and addr are changed, do fast csum update */ 270 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr, 271 cp->vport, cp->dport); 272 if (skb->ip_summed == CHECKSUM_COMPLETE) 273 skb->ip_summed = (cp->app && pp->csum_check) ? 274 CHECKSUM_UNNECESSARY : CHECKSUM_NONE; 275 } else { 276 /* full checksum calculation */ 277 udph->check = 0; 278 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0); 279 #ifdef CONFIG_IP_VS_IPV6 280 if (cp->af == AF_INET6) 281 udph->check = csum_ipv6_magic(&cp->caddr.in6, 282 &cp->daddr.in6, 283 skb->len - udphoff, 284 cp->protocol, skb->csum); 285 else 286 #endif 287 udph->check = csum_tcpudp_magic(cp->caddr.ip, 288 cp->daddr.ip, 289 skb->len - udphoff, 290 cp->protocol, 291 skb->csum); 292 if (udph->check == 0) 293 udph->check = CSUM_MANGLED_0; 294 skb->ip_summed = CHECKSUM_UNNECESSARY; 295 } 296 return 1; 297 } 298 299 300 static int 301 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) 302 { 303 struct udphdr _udph, *uh; 304 unsigned int udphoff; 305 306 #ifdef CONFIG_IP_VS_IPV6 307 if (af == AF_INET6) 308 udphoff = sizeof(struct ipv6hdr); 309 else 310 #endif 311 udphoff = ip_hdrlen(skb); 312 313 uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph); 314 if (uh == NULL) 315 return 0; 316 317 if (uh->check != 0) { 318 switch (skb->ip_summed) { 319 case CHECKSUM_NONE: 320 skb->csum = skb_checksum(skb, udphoff, 321 skb->len - udphoff, 0); 322 /* fall through */ 323 case CHECKSUM_COMPLETE: 324 #ifdef CONFIG_IP_VS_IPV6 325 if (af == AF_INET6) { 326 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr, 327 &ipv6_hdr(skb)->daddr, 328 skb->len - udphoff, 329 ipv6_hdr(skb)->nexthdr, 330 skb->csum)) { 331 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0, 332 "Failed checksum for"); 333 return 0; 334 } 335 } else 336 #endif 337 if (csum_tcpudp_magic(ip_hdr(skb)->saddr, 338 ip_hdr(skb)->daddr, 339 skb->len - udphoff, 340 ip_hdr(skb)->protocol, 341 skb->csum)) { 342 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0, 343 "Failed checksum for"); 344 return 0; 345 } 346 break; 347 default: 348 /* No need to checksum. */ 349 break; 350 } 351 } 352 return 1; 353 } 354 355 static inline __u16 udp_app_hashkey(__be16 port) 356 { 357 return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port) 358 & UDP_APP_TAB_MASK; 359 } 360 361 362 static int udp_register_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc) 363 { 364 struct ip_vs_app *i; 365 __u16 hash; 366 __be16 port = inc->port; 367 int ret = 0; 368 struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP); 369 370 hash = udp_app_hashkey(port); 371 372 list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) { 373 if (i->port == port) { 374 ret = -EEXIST; 375 goto out; 376 } 377 } 378 list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]); 379 atomic_inc(&pd->appcnt); 380 381 out: 382 return ret; 383 } 384 385 386 static void 387 udp_unregister_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc) 388 { 389 struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP); 390 391 atomic_dec(&pd->appcnt); 392 list_del_rcu(&inc->p_list); 393 } 394 395 396 static int udp_app_conn_bind(struct ip_vs_conn *cp) 397 { 398 struct netns_ipvs *ipvs = cp->ipvs; 399 int hash; 400 struct ip_vs_app *inc; 401 int result = 0; 402 403 /* Default binding: bind app only for NAT */ 404 if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) 405 return 0; 406 407 /* Lookup application incarnations and bind the right one */ 408 hash = udp_app_hashkey(cp->vport); 409 410 list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) { 411 if (inc->port == cp->vport) { 412 if (unlikely(!ip_vs_app_inc_get(inc))) 413 break; 414 415 IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->" 416 "%s:%u to app %s on port %u\n", 417 __func__, 418 IP_VS_DBG_ADDR(cp->af, &cp->caddr), 419 ntohs(cp->cport), 420 IP_VS_DBG_ADDR(cp->af, &cp->vaddr), 421 ntohs(cp->vport), 422 inc->name, ntohs(inc->port)); 423 424 cp->app = inc; 425 if (inc->init_conn) 426 result = inc->init_conn(inc, cp); 427 break; 428 } 429 } 430 431 return result; 432 } 433 434 435 static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = { 436 [IP_VS_UDP_S_NORMAL] = 5*60*HZ, 437 [IP_VS_UDP_S_LAST] = 2*HZ, 438 }; 439 440 static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = { 441 [IP_VS_UDP_S_NORMAL] = "UDP", 442 [IP_VS_UDP_S_LAST] = "BUG!", 443 }; 444 445 static const char * udp_state_name(int state) 446 { 447 if (state >= IP_VS_UDP_S_LAST) 448 return "ERR!"; 449 return udp_state_name_table[state] ? udp_state_name_table[state] : "?"; 450 } 451 452 static void 453 udp_state_transition(struct ip_vs_conn *cp, int direction, 454 const struct sk_buff *skb, 455 struct ip_vs_proto_data *pd) 456 { 457 if (unlikely(!pd)) { 458 pr_err("UDP no ns data\n"); 459 return; 460 } 461 462 cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL]; 463 } 464 465 static int __udp_init(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd) 466 { 467 ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE); 468 pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts, 469 sizeof(udp_timeouts)); 470 if (!pd->timeout_table) 471 return -ENOMEM; 472 return 0; 473 } 474 475 static void __udp_exit(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd) 476 { 477 kfree(pd->timeout_table); 478 } 479 480 481 struct ip_vs_protocol ip_vs_protocol_udp = { 482 .name = "UDP", 483 .protocol = IPPROTO_UDP, 484 .num_states = IP_VS_UDP_S_LAST, 485 .dont_defrag = 0, 486 .init = NULL, 487 .exit = NULL, 488 .init_netns = __udp_init, 489 .exit_netns = __udp_exit, 490 .conn_schedule = udp_conn_schedule, 491 .conn_in_get = ip_vs_conn_in_get_proto, 492 .conn_out_get = ip_vs_conn_out_get_proto, 493 .snat_handler = udp_snat_handler, 494 .dnat_handler = udp_dnat_handler, 495 .csum_check = udp_csum_check, 496 .state_transition = udp_state_transition, 497 .state_name = udp_state_name, 498 .register_app = udp_register_app, 499 .unregister_app = udp_unregister_app, 500 .app_conn_bind = udp_app_conn_bind, 501 .debug_packet = ip_vs_tcpudp_debug_packet, 502 .timeout_change = NULL, 503 }; 504