1 /* 2 * net/dccp/ipv4.c 3 * 4 * An implementation of the DCCP protocol 5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 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 13 #include <linux/dccp.h> 14 #include <linux/icmp.h> 15 #include <linux/slab.h> 16 #include <linux/module.h> 17 #include <linux/skbuff.h> 18 #include <linux/random.h> 19 20 #include <net/icmp.h> 21 #include <net/inet_common.h> 22 #include <net/inet_hashtables.h> 23 #include <net/inet_sock.h> 24 #include <net/protocol.h> 25 #include <net/sock.h> 26 #include <net/timewait_sock.h> 27 #include <net/tcp_states.h> 28 #include <net/xfrm.h> 29 30 #include "ackvec.h" 31 #include "ccid.h" 32 #include "dccp.h" 33 #include "feat.h" 34 35 /* 36 * The per-net dccp.v4_ctl_sk socket is used for responding to 37 * the Out-of-the-blue (OOTB) packets. A control sock will be created 38 * for this socket at the initialization time. 39 */ 40 41 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 42 { 43 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 44 struct inet_sock *inet = inet_sk(sk); 45 struct dccp_sock *dp = dccp_sk(sk); 46 __be16 orig_sport, orig_dport; 47 __be32 daddr, nexthop; 48 struct flowi4 *fl4; 49 struct rtable *rt; 50 int err; 51 struct ip_options_rcu *inet_opt; 52 53 dp->dccps_role = DCCP_ROLE_CLIENT; 54 55 if (addr_len < sizeof(struct sockaddr_in)) 56 return -EINVAL; 57 58 if (usin->sin_family != AF_INET) 59 return -EAFNOSUPPORT; 60 61 nexthop = daddr = usin->sin_addr.s_addr; 62 63 inet_opt = rcu_dereference_protected(inet->inet_opt, 64 sock_owned_by_user(sk)); 65 if (inet_opt != NULL && inet_opt->opt.srr) { 66 if (daddr == 0) 67 return -EINVAL; 68 nexthop = inet_opt->opt.faddr; 69 } 70 71 orig_sport = inet->inet_sport; 72 orig_dport = usin->sin_port; 73 fl4 = &inet->cork.fl.u.ip4; 74 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 75 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 76 IPPROTO_DCCP, 77 orig_sport, orig_dport, sk, true); 78 if (IS_ERR(rt)) 79 return PTR_ERR(rt); 80 81 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 82 ip_rt_put(rt); 83 return -ENETUNREACH; 84 } 85 86 if (inet_opt == NULL || !inet_opt->opt.srr) 87 daddr = fl4->daddr; 88 89 if (inet->inet_saddr == 0) 90 inet->inet_saddr = fl4->saddr; 91 inet->inet_rcv_saddr = inet->inet_saddr; 92 93 inet->inet_dport = usin->sin_port; 94 inet->inet_daddr = daddr; 95 96 inet_csk(sk)->icsk_ext_hdr_len = 0; 97 if (inet_opt) 98 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 99 /* 100 * Socket identity is still unknown (sport may be zero). 101 * However we set state to DCCP_REQUESTING and not releasing socket 102 * lock select source port, enter ourselves into the hash tables and 103 * complete initialization after this. 104 */ 105 dccp_set_state(sk, DCCP_REQUESTING); 106 err = inet_hash_connect(&dccp_death_row, sk); 107 if (err != 0) 108 goto failure; 109 110 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 111 inet->inet_sport, inet->inet_dport, sk); 112 if (IS_ERR(rt)) { 113 rt = NULL; 114 goto failure; 115 } 116 /* OK, now commit destination to socket. */ 117 sk_setup_caps(sk, &rt->dst); 118 119 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 120 inet->inet_daddr, 121 inet->inet_sport, 122 inet->inet_dport); 123 inet->inet_id = dp->dccps_iss ^ jiffies; 124 125 err = dccp_connect(sk); 126 rt = NULL; 127 if (err != 0) 128 goto failure; 129 out: 130 return err; 131 failure: 132 /* 133 * This unhashes the socket and releases the local port, if necessary. 134 */ 135 dccp_set_state(sk, DCCP_CLOSED); 136 ip_rt_put(rt); 137 sk->sk_route_caps = 0; 138 inet->inet_dport = 0; 139 goto out; 140 } 141 142 EXPORT_SYMBOL_GPL(dccp_v4_connect); 143 144 /* 145 * This routine does path mtu discovery as defined in RFC1191. 146 */ 147 static inline void dccp_do_pmtu_discovery(struct sock *sk, 148 const struct iphdr *iph, 149 u32 mtu) 150 { 151 struct dst_entry *dst; 152 const struct inet_sock *inet = inet_sk(sk); 153 const struct dccp_sock *dp = dccp_sk(sk); 154 155 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 156 * send out by Linux are always < 576bytes so they should go through 157 * unfragmented). 158 */ 159 if (sk->sk_state == DCCP_LISTEN) 160 return; 161 162 /* We don't check in the destentry if pmtu discovery is forbidden 163 * on this route. We just assume that no packet_to_big packets 164 * are send back when pmtu discovery is not active. 165 * There is a small race when the user changes this flag in the 166 * route, but I think that's acceptable. 167 */ 168 if ((dst = __sk_dst_check(sk, 0)) == NULL) 169 return; 170 171 dst->ops->update_pmtu(dst, mtu); 172 173 /* Something is about to be wrong... Remember soft error 174 * for the case, if this connection will not able to recover. 175 */ 176 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 177 sk->sk_err_soft = EMSGSIZE; 178 179 mtu = dst_mtu(dst); 180 181 if (inet->pmtudisc != IP_PMTUDISC_DONT && 182 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 183 dccp_sync_mss(sk, mtu); 184 185 /* 186 * From RFC 4340, sec. 14.1: 187 * 188 * DCCP-Sync packets are the best choice for upward 189 * probing, since DCCP-Sync probes do not risk application 190 * data loss. 191 */ 192 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 193 } /* else let the usual retransmit timer handle it */ 194 } 195 196 /* 197 * This routine is called by the ICMP module when it gets some sort of error 198 * condition. If err < 0 then the socket should be closed and the error 199 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 200 * After adjustment header points to the first 8 bytes of the tcp header. We 201 * need to find the appropriate port. 202 * 203 * The locking strategy used here is very "optimistic". When someone else 204 * accesses the socket the ICMP is just dropped and for some paths there is no 205 * check at all. A more general error queue to queue errors for later handling 206 * is probably better. 207 */ 208 static void dccp_v4_err(struct sk_buff *skb, u32 info) 209 { 210 const struct iphdr *iph = (struct iphdr *)skb->data; 211 const u8 offset = iph->ihl << 2; 212 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 213 struct dccp_sock *dp; 214 struct inet_sock *inet; 215 const int type = icmp_hdr(skb)->type; 216 const int code = icmp_hdr(skb)->code; 217 struct sock *sk; 218 __u64 seq; 219 int err; 220 struct net *net = dev_net(skb->dev); 221 222 if (skb->len < offset + sizeof(*dh) || 223 skb->len < offset + __dccp_basic_hdr_len(dh)) { 224 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 225 return; 226 } 227 228 sk = inet_lookup(net, &dccp_hashinfo, 229 iph->daddr, dh->dccph_dport, 230 iph->saddr, dh->dccph_sport, inet_iif(skb)); 231 if (sk == NULL) { 232 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 233 return; 234 } 235 236 if (sk->sk_state == DCCP_TIME_WAIT) { 237 inet_twsk_put(inet_twsk(sk)); 238 return; 239 } 240 241 bh_lock_sock(sk); 242 /* If too many ICMPs get dropped on busy 243 * servers this needs to be solved differently. 244 */ 245 if (sock_owned_by_user(sk)) 246 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 247 248 if (sk->sk_state == DCCP_CLOSED) 249 goto out; 250 251 dp = dccp_sk(sk); 252 seq = dccp_hdr_seq(dh); 253 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 254 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 255 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 256 goto out; 257 } 258 259 switch (type) { 260 case ICMP_SOURCE_QUENCH: 261 /* Just silently ignore these. */ 262 goto out; 263 case ICMP_PARAMETERPROB: 264 err = EPROTO; 265 break; 266 case ICMP_DEST_UNREACH: 267 if (code > NR_ICMP_UNREACH) 268 goto out; 269 270 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 271 if (!sock_owned_by_user(sk)) 272 dccp_do_pmtu_discovery(sk, iph, info); 273 goto out; 274 } 275 276 err = icmp_err_convert[code].errno; 277 break; 278 case ICMP_TIME_EXCEEDED: 279 err = EHOSTUNREACH; 280 break; 281 default: 282 goto out; 283 } 284 285 switch (sk->sk_state) { 286 struct request_sock *req , **prev; 287 case DCCP_LISTEN: 288 if (sock_owned_by_user(sk)) 289 goto out; 290 req = inet_csk_search_req(sk, &prev, dh->dccph_dport, 291 iph->daddr, iph->saddr); 292 if (!req) 293 goto out; 294 295 /* 296 * ICMPs are not backlogged, hence we cannot get an established 297 * socket here. 298 */ 299 WARN_ON(req->sk); 300 301 if (seq != dccp_rsk(req)->dreq_iss) { 302 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 303 goto out; 304 } 305 /* 306 * Still in RESPOND, just remove it silently. 307 * There is no good way to pass the error to the newly 308 * created socket, and POSIX does not want network 309 * errors returned from accept(). 310 */ 311 inet_csk_reqsk_queue_drop(sk, req, prev); 312 goto out; 313 314 case DCCP_REQUESTING: 315 case DCCP_RESPOND: 316 if (!sock_owned_by_user(sk)) { 317 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 318 sk->sk_err = err; 319 320 sk->sk_error_report(sk); 321 322 dccp_done(sk); 323 } else 324 sk->sk_err_soft = err; 325 goto out; 326 } 327 328 /* If we've already connected we will keep trying 329 * until we time out, or the user gives up. 330 * 331 * rfc1122 4.2.3.9 allows to consider as hard errors 332 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 333 * but it is obsoleted by pmtu discovery). 334 * 335 * Note, that in modern internet, where routing is unreliable 336 * and in each dark corner broken firewalls sit, sending random 337 * errors ordered by their masters even this two messages finally lose 338 * their original sense (even Linux sends invalid PORT_UNREACHs) 339 * 340 * Now we are in compliance with RFCs. 341 * --ANK (980905) 342 */ 343 344 inet = inet_sk(sk); 345 if (!sock_owned_by_user(sk) && inet->recverr) { 346 sk->sk_err = err; 347 sk->sk_error_report(sk); 348 } else /* Only an error on timeout */ 349 sk->sk_err_soft = err; 350 out: 351 bh_unlock_sock(sk); 352 sock_put(sk); 353 } 354 355 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 356 __be32 src, __be32 dst) 357 { 358 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 359 } 360 361 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 362 { 363 const struct inet_sock *inet = inet_sk(sk); 364 struct dccp_hdr *dh = dccp_hdr(skb); 365 366 dccp_csum_outgoing(skb); 367 dh->dccph_checksum = dccp_v4_csum_finish(skb, 368 inet->inet_saddr, 369 inet->inet_daddr); 370 } 371 372 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 373 374 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 375 { 376 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 377 ip_hdr(skb)->saddr, 378 dccp_hdr(skb)->dccph_dport, 379 dccp_hdr(skb)->dccph_sport); 380 } 381 382 /* 383 * The three way handshake has completed - we got a valid ACK or DATAACK - 384 * now create the new socket. 385 * 386 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 387 */ 388 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 389 struct request_sock *req, 390 struct dst_entry *dst) 391 { 392 struct inet_request_sock *ireq; 393 struct inet_sock *newinet; 394 struct sock *newsk; 395 396 if (sk_acceptq_is_full(sk)) 397 goto exit_overflow; 398 399 newsk = dccp_create_openreq_child(sk, req, skb); 400 if (newsk == NULL) 401 goto exit_nonewsk; 402 403 newinet = inet_sk(newsk); 404 ireq = inet_rsk(req); 405 newinet->inet_daddr = ireq->rmt_addr; 406 newinet->inet_rcv_saddr = ireq->loc_addr; 407 newinet->inet_saddr = ireq->loc_addr; 408 newinet->inet_opt = ireq->opt; 409 ireq->opt = NULL; 410 newinet->mc_index = inet_iif(skb); 411 newinet->mc_ttl = ip_hdr(skb)->ttl; 412 newinet->inet_id = jiffies; 413 414 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 415 goto put_and_exit; 416 417 sk_setup_caps(newsk, dst); 418 419 dccp_sync_mss(newsk, dst_mtu(dst)); 420 421 if (__inet_inherit_port(sk, newsk) < 0) 422 goto put_and_exit; 423 __inet_hash_nolisten(newsk, NULL); 424 425 return newsk; 426 427 exit_overflow: 428 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 429 exit_nonewsk: 430 dst_release(dst); 431 exit: 432 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 433 return NULL; 434 put_and_exit: 435 sock_put(newsk); 436 goto exit; 437 } 438 439 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 440 441 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 442 { 443 const struct dccp_hdr *dh = dccp_hdr(skb); 444 const struct iphdr *iph = ip_hdr(skb); 445 struct sock *nsk; 446 struct request_sock **prev; 447 /* Find possible connection requests. */ 448 struct request_sock *req = inet_csk_search_req(sk, &prev, 449 dh->dccph_sport, 450 iph->saddr, iph->daddr); 451 if (req != NULL) 452 return dccp_check_req(sk, skb, req, prev); 453 454 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo, 455 iph->saddr, dh->dccph_sport, 456 iph->daddr, dh->dccph_dport, 457 inet_iif(skb)); 458 if (nsk != NULL) { 459 if (nsk->sk_state != DCCP_TIME_WAIT) { 460 bh_lock_sock(nsk); 461 return nsk; 462 } 463 inet_twsk_put(inet_twsk(nsk)); 464 return NULL; 465 } 466 467 return sk; 468 } 469 470 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 471 struct sk_buff *skb) 472 { 473 struct rtable *rt; 474 struct flowi4 fl4 = { 475 .flowi4_oif = skb_rtable(skb)->rt_iif, 476 .daddr = ip_hdr(skb)->saddr, 477 .saddr = ip_hdr(skb)->daddr, 478 .flowi4_tos = RT_CONN_FLAGS(sk), 479 .flowi4_proto = sk->sk_protocol, 480 .fl4_sport = dccp_hdr(skb)->dccph_dport, 481 .fl4_dport = dccp_hdr(skb)->dccph_sport, 482 }; 483 484 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 485 rt = ip_route_output_flow(net, &fl4, sk); 486 if (IS_ERR(rt)) { 487 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES); 488 return NULL; 489 } 490 491 return &rt->dst; 492 } 493 494 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req, 495 struct request_values *rv_unused) 496 { 497 int err = -1; 498 struct sk_buff *skb; 499 struct dst_entry *dst; 500 struct flowi4 fl4; 501 502 dst = inet_csk_route_req(sk, &fl4, req); 503 if (dst == NULL) 504 goto out; 505 506 skb = dccp_make_response(sk, dst, req); 507 if (skb != NULL) { 508 const struct inet_request_sock *ireq = inet_rsk(req); 509 struct dccp_hdr *dh = dccp_hdr(skb); 510 511 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr, 512 ireq->rmt_addr); 513 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 514 ireq->rmt_addr, 515 ireq->opt); 516 err = net_xmit_eval(err); 517 } 518 519 out: 520 dst_release(dst); 521 return err; 522 } 523 524 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 525 { 526 int err; 527 const struct iphdr *rxiph; 528 struct sk_buff *skb; 529 struct dst_entry *dst; 530 struct net *net = dev_net(skb_dst(rxskb)->dev); 531 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 532 533 /* Never send a reset in response to a reset. */ 534 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 535 return; 536 537 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 538 return; 539 540 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 541 if (dst == NULL) 542 return; 543 544 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 545 if (skb == NULL) 546 goto out; 547 548 rxiph = ip_hdr(rxskb); 549 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 550 rxiph->daddr); 551 skb_dst_set(skb, dst_clone(dst)); 552 553 bh_lock_sock(ctl_sk); 554 err = ip_build_and_send_pkt(skb, ctl_sk, 555 rxiph->daddr, rxiph->saddr, NULL); 556 bh_unlock_sock(ctl_sk); 557 558 if (net_xmit_eval(err) == 0) { 559 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 560 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 561 } 562 out: 563 dst_release(dst); 564 } 565 566 static void dccp_v4_reqsk_destructor(struct request_sock *req) 567 { 568 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 569 kfree(inet_rsk(req)->opt); 570 } 571 572 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 573 .family = PF_INET, 574 .obj_size = sizeof(struct dccp_request_sock), 575 .rtx_syn_ack = dccp_v4_send_response, 576 .send_ack = dccp_reqsk_send_ack, 577 .destructor = dccp_v4_reqsk_destructor, 578 .send_reset = dccp_v4_ctl_send_reset, 579 }; 580 581 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 582 { 583 struct inet_request_sock *ireq; 584 struct request_sock *req; 585 struct dccp_request_sock *dreq; 586 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 587 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 588 589 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 590 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 591 return 0; /* discard, don't send a reset here */ 592 593 if (dccp_bad_service_code(sk, service)) { 594 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 595 goto drop; 596 } 597 /* 598 * TW buckets are converted to open requests without 599 * limitations, they conserve resources and peer is 600 * evidently real one. 601 */ 602 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 603 if (inet_csk_reqsk_queue_is_full(sk)) 604 goto drop; 605 606 /* 607 * Accept backlog is full. If we have already queued enough 608 * of warm entries in syn queue, drop request. It is better than 609 * clogging syn queue with openreqs with exponentially increasing 610 * timeout. 611 */ 612 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 613 goto drop; 614 615 req = inet_reqsk_alloc(&dccp_request_sock_ops); 616 if (req == NULL) 617 goto drop; 618 619 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 620 goto drop_and_free; 621 622 dreq = dccp_rsk(req); 623 if (dccp_parse_options(sk, dreq, skb)) 624 goto drop_and_free; 625 626 if (security_inet_conn_request(sk, skb, req)) 627 goto drop_and_free; 628 629 ireq = inet_rsk(req); 630 ireq->loc_addr = ip_hdr(skb)->daddr; 631 ireq->rmt_addr = ip_hdr(skb)->saddr; 632 633 /* 634 * Step 3: Process LISTEN state 635 * 636 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 637 * 638 * In fact we defer setting S.GSR, S.SWL, S.SWH to 639 * dccp_create_openreq_child. 640 */ 641 dreq->dreq_isr = dcb->dccpd_seq; 642 dreq->dreq_iss = dccp_v4_init_sequence(skb); 643 dreq->dreq_service = service; 644 645 if (dccp_v4_send_response(sk, req, NULL)) 646 goto drop_and_free; 647 648 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 649 return 0; 650 651 drop_and_free: 652 reqsk_free(req); 653 drop: 654 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 655 return -1; 656 } 657 658 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 659 660 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 661 { 662 struct dccp_hdr *dh = dccp_hdr(skb); 663 664 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 665 if (dccp_rcv_established(sk, skb, dh, skb->len)) 666 goto reset; 667 return 0; 668 } 669 670 /* 671 * Step 3: Process LISTEN state 672 * If P.type == Request or P contains a valid Init Cookie option, 673 * (* Must scan the packet's options to check for Init 674 * Cookies. Only Init Cookies are processed here, 675 * however; other options are processed in Step 8. This 676 * scan need only be performed if the endpoint uses Init 677 * Cookies *) 678 * (* Generate a new socket and switch to that socket *) 679 * Set S := new socket for this port pair 680 * S.state = RESPOND 681 * Choose S.ISS (initial seqno) or set from Init Cookies 682 * Initialize S.GAR := S.ISS 683 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 684 * Continue with S.state == RESPOND 685 * (* A Response packet will be generated in Step 11 *) 686 * Otherwise, 687 * Generate Reset(No Connection) unless P.type == Reset 688 * Drop packet and return 689 * 690 * NOTE: the check for the packet types is done in 691 * dccp_rcv_state_process 692 */ 693 if (sk->sk_state == DCCP_LISTEN) { 694 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 695 696 if (nsk == NULL) 697 goto discard; 698 699 if (nsk != sk) { 700 if (dccp_child_process(sk, nsk, skb)) 701 goto reset; 702 return 0; 703 } 704 } 705 706 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 707 goto reset; 708 return 0; 709 710 reset: 711 dccp_v4_ctl_send_reset(sk, skb); 712 discard: 713 kfree_skb(skb); 714 return 0; 715 } 716 717 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 718 719 /** 720 * dccp_invalid_packet - check for malformed packets 721 * Implements RFC 4340, 8.5: Step 1: Check header basics 722 * Packets that fail these checks are ignored and do not receive Resets. 723 */ 724 int dccp_invalid_packet(struct sk_buff *skb) 725 { 726 const struct dccp_hdr *dh; 727 unsigned int cscov; 728 729 if (skb->pkt_type != PACKET_HOST) 730 return 1; 731 732 /* If the packet is shorter than 12 bytes, drop packet and return */ 733 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 734 DCCP_WARN("pskb_may_pull failed\n"); 735 return 1; 736 } 737 738 dh = dccp_hdr(skb); 739 740 /* If P.type is not understood, drop packet and return */ 741 if (dh->dccph_type >= DCCP_PKT_INVALID) { 742 DCCP_WARN("invalid packet type\n"); 743 return 1; 744 } 745 746 /* 747 * If P.Data Offset is too small for packet type, drop packet and return 748 */ 749 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 750 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 751 return 1; 752 } 753 /* 754 * If P.Data Offset is too too large for packet, drop packet and return 755 */ 756 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 757 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 758 return 1; 759 } 760 761 /* 762 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 763 * has short sequence numbers), drop packet and return 764 */ 765 if ((dh->dccph_type < DCCP_PKT_DATA || 766 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 767 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 768 dccp_packet_name(dh->dccph_type)); 769 return 1; 770 } 771 772 /* 773 * If P.CsCov is too large for the packet size, drop packet and return. 774 * This must come _before_ checksumming (not as RFC 4340 suggests). 775 */ 776 cscov = dccp_csum_coverage(skb); 777 if (cscov > skb->len) { 778 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 779 dh->dccph_cscov, skb->len); 780 return 1; 781 } 782 783 /* If header checksum is incorrect, drop packet and return. 784 * (This step is completed in the AF-dependent functions.) */ 785 skb->csum = skb_checksum(skb, 0, cscov, 0); 786 787 return 0; 788 } 789 790 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 791 792 /* this is called when real data arrives */ 793 static int dccp_v4_rcv(struct sk_buff *skb) 794 { 795 const struct dccp_hdr *dh; 796 const struct iphdr *iph; 797 struct sock *sk; 798 int min_cov; 799 800 /* Step 1: Check header basics */ 801 802 if (dccp_invalid_packet(skb)) 803 goto discard_it; 804 805 iph = ip_hdr(skb); 806 /* Step 1: If header checksum is incorrect, drop packet and return */ 807 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 808 DCCP_WARN("dropped packet with invalid checksum\n"); 809 goto discard_it; 810 } 811 812 dh = dccp_hdr(skb); 813 814 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 815 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 816 817 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 818 dccp_packet_name(dh->dccph_type), 819 &iph->saddr, ntohs(dh->dccph_sport), 820 &iph->daddr, ntohs(dh->dccph_dport), 821 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 822 823 if (dccp_packet_without_ack(skb)) { 824 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 825 dccp_pr_debug_cat("\n"); 826 } else { 827 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 828 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 829 DCCP_SKB_CB(skb)->dccpd_ack_seq); 830 } 831 832 /* Step 2: 833 * Look up flow ID in table and get corresponding socket */ 834 sk = __inet_lookup_skb(&dccp_hashinfo, skb, 835 dh->dccph_sport, dh->dccph_dport); 836 /* 837 * Step 2: 838 * If no socket ... 839 */ 840 if (sk == NULL) { 841 dccp_pr_debug("failed to look up flow ID in table and " 842 "get corresponding socket\n"); 843 goto no_dccp_socket; 844 } 845 846 /* 847 * Step 2: 848 * ... or S.state == TIMEWAIT, 849 * Generate Reset(No Connection) unless P.type == Reset 850 * Drop packet and return 851 */ 852 if (sk->sk_state == DCCP_TIME_WAIT) { 853 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 854 inet_twsk_put(inet_twsk(sk)); 855 goto no_dccp_socket; 856 } 857 858 /* 859 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 860 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 861 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 862 */ 863 min_cov = dccp_sk(sk)->dccps_pcrlen; 864 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 865 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 866 dh->dccph_cscov, min_cov); 867 /* FIXME: "Such packets SHOULD be reported using Data Dropped 868 * options (Section 11.7) with Drop Code 0, Protocol 869 * Constraints." */ 870 goto discard_and_relse; 871 } 872 873 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 874 goto discard_and_relse; 875 nf_reset(skb); 876 877 return sk_receive_skb(sk, skb, 1); 878 879 no_dccp_socket: 880 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 881 goto discard_it; 882 /* 883 * Step 2: 884 * If no socket ... 885 * Generate Reset(No Connection) unless P.type == Reset 886 * Drop packet and return 887 */ 888 if (dh->dccph_type != DCCP_PKT_RESET) { 889 DCCP_SKB_CB(skb)->dccpd_reset_code = 890 DCCP_RESET_CODE_NO_CONNECTION; 891 dccp_v4_ctl_send_reset(sk, skb); 892 } 893 894 discard_it: 895 kfree_skb(skb); 896 return 0; 897 898 discard_and_relse: 899 sock_put(sk); 900 goto discard_it; 901 } 902 903 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 904 .queue_xmit = ip_queue_xmit, 905 .send_check = dccp_v4_send_check, 906 .rebuild_header = inet_sk_rebuild_header, 907 .conn_request = dccp_v4_conn_request, 908 .syn_recv_sock = dccp_v4_request_recv_sock, 909 .net_header_len = sizeof(struct iphdr), 910 .setsockopt = ip_setsockopt, 911 .getsockopt = ip_getsockopt, 912 .addr2sockaddr = inet_csk_addr2sockaddr, 913 .sockaddr_len = sizeof(struct sockaddr_in), 914 .bind_conflict = inet_csk_bind_conflict, 915 #ifdef CONFIG_COMPAT 916 .compat_setsockopt = compat_ip_setsockopt, 917 .compat_getsockopt = compat_ip_getsockopt, 918 #endif 919 }; 920 921 static int dccp_v4_init_sock(struct sock *sk) 922 { 923 static __u8 dccp_v4_ctl_sock_initialized; 924 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 925 926 if (err == 0) { 927 if (unlikely(!dccp_v4_ctl_sock_initialized)) 928 dccp_v4_ctl_sock_initialized = 1; 929 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 930 } 931 932 return err; 933 } 934 935 static struct timewait_sock_ops dccp_timewait_sock_ops = { 936 .twsk_obj_size = sizeof(struct inet_timewait_sock), 937 }; 938 939 static struct proto dccp_v4_prot = { 940 .name = "DCCP", 941 .owner = THIS_MODULE, 942 .close = dccp_close, 943 .connect = dccp_v4_connect, 944 .disconnect = dccp_disconnect, 945 .ioctl = dccp_ioctl, 946 .init = dccp_v4_init_sock, 947 .setsockopt = dccp_setsockopt, 948 .getsockopt = dccp_getsockopt, 949 .sendmsg = dccp_sendmsg, 950 .recvmsg = dccp_recvmsg, 951 .backlog_rcv = dccp_v4_do_rcv, 952 .hash = inet_hash, 953 .unhash = inet_unhash, 954 .accept = inet_csk_accept, 955 .get_port = inet_csk_get_port, 956 .shutdown = dccp_shutdown, 957 .destroy = dccp_destroy_sock, 958 .orphan_count = &dccp_orphan_count, 959 .max_header = MAX_DCCP_HEADER, 960 .obj_size = sizeof(struct dccp_sock), 961 .slab_flags = SLAB_DESTROY_BY_RCU, 962 .rsk_prot = &dccp_request_sock_ops, 963 .twsk_prot = &dccp_timewait_sock_ops, 964 .h.hashinfo = &dccp_hashinfo, 965 #ifdef CONFIG_COMPAT 966 .compat_setsockopt = compat_dccp_setsockopt, 967 .compat_getsockopt = compat_dccp_getsockopt, 968 #endif 969 }; 970 971 static const struct net_protocol dccp_v4_protocol = { 972 .handler = dccp_v4_rcv, 973 .err_handler = dccp_v4_err, 974 .no_policy = 1, 975 .netns_ok = 1, 976 }; 977 978 static const struct proto_ops inet_dccp_ops = { 979 .family = PF_INET, 980 .owner = THIS_MODULE, 981 .release = inet_release, 982 .bind = inet_bind, 983 .connect = inet_stream_connect, 984 .socketpair = sock_no_socketpair, 985 .accept = inet_accept, 986 .getname = inet_getname, 987 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 988 .poll = dccp_poll, 989 .ioctl = inet_ioctl, 990 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 991 .listen = inet_dccp_listen, 992 .shutdown = inet_shutdown, 993 .setsockopt = sock_common_setsockopt, 994 .getsockopt = sock_common_getsockopt, 995 .sendmsg = inet_sendmsg, 996 .recvmsg = sock_common_recvmsg, 997 .mmap = sock_no_mmap, 998 .sendpage = sock_no_sendpage, 999 #ifdef CONFIG_COMPAT 1000 .compat_setsockopt = compat_sock_common_setsockopt, 1001 .compat_getsockopt = compat_sock_common_getsockopt, 1002 #endif 1003 }; 1004 1005 static struct inet_protosw dccp_v4_protosw = { 1006 .type = SOCK_DCCP, 1007 .protocol = IPPROTO_DCCP, 1008 .prot = &dccp_v4_prot, 1009 .ops = &inet_dccp_ops, 1010 .no_check = 0, 1011 .flags = INET_PROTOSW_ICSK, 1012 }; 1013 1014 static int __net_init dccp_v4_init_net(struct net *net) 1015 { 1016 if (dccp_hashinfo.bhash == NULL) 1017 return -ESOCKTNOSUPPORT; 1018 1019 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1020 SOCK_DCCP, IPPROTO_DCCP, net); 1021 } 1022 1023 static void __net_exit dccp_v4_exit_net(struct net *net) 1024 { 1025 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1026 } 1027 1028 static struct pernet_operations dccp_v4_ops = { 1029 .init = dccp_v4_init_net, 1030 .exit = dccp_v4_exit_net, 1031 }; 1032 1033 static int __init dccp_v4_init(void) 1034 { 1035 int err = proto_register(&dccp_v4_prot, 1); 1036 1037 if (err != 0) 1038 goto out; 1039 1040 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1041 if (err != 0) 1042 goto out_proto_unregister; 1043 1044 inet_register_protosw(&dccp_v4_protosw); 1045 1046 err = register_pernet_subsys(&dccp_v4_ops); 1047 if (err) 1048 goto out_destroy_ctl_sock; 1049 out: 1050 return err; 1051 out_destroy_ctl_sock: 1052 inet_unregister_protosw(&dccp_v4_protosw); 1053 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1054 out_proto_unregister: 1055 proto_unregister(&dccp_v4_prot); 1056 goto out; 1057 } 1058 1059 static void __exit dccp_v4_exit(void) 1060 { 1061 unregister_pernet_subsys(&dccp_v4_ops); 1062 inet_unregister_protosw(&dccp_v4_protosw); 1063 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1064 proto_unregister(&dccp_v4_prot); 1065 } 1066 1067 module_init(dccp_v4_init); 1068 module_exit(dccp_v4_exit); 1069 1070 /* 1071 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1072 * values directly, Also cover the case where the protocol is not specified, 1073 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1074 */ 1075 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1076 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1077 MODULE_LICENSE("GPL"); 1078 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1079 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1080