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 #include <net/secure_seq.h> 30 31 #include "ackvec.h" 32 #include "ccid.h" 33 #include "dccp.h" 34 #include "feat.h" 35 36 /* 37 * The per-net dccp.v4_ctl_sk socket is used for responding to 38 * the Out-of-the-blue (OOTB) packets. A control sock will be created 39 * for this socket at the initialization time. 40 */ 41 42 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 43 { 44 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 45 struct inet_sock *inet = inet_sk(sk); 46 struct dccp_sock *dp = dccp_sk(sk); 47 __be16 orig_sport, orig_dport; 48 __be32 daddr, nexthop; 49 struct flowi4 *fl4; 50 struct rtable *rt; 51 int err; 52 struct ip_options_rcu *inet_opt; 53 54 dp->dccps_role = DCCP_ROLE_CLIENT; 55 56 if (addr_len < sizeof(struct sockaddr_in)) 57 return -EINVAL; 58 59 if (usin->sin_family != AF_INET) 60 return -EAFNOSUPPORT; 61 62 nexthop = daddr = usin->sin_addr.s_addr; 63 64 inet_opt = rcu_dereference_protected(inet->inet_opt, 65 sock_owned_by_user(sk)); 66 if (inet_opt != NULL && inet_opt->opt.srr) { 67 if (daddr == 0) 68 return -EINVAL; 69 nexthop = inet_opt->opt.faddr; 70 } 71 72 orig_sport = inet->inet_sport; 73 orig_dport = usin->sin_port; 74 fl4 = &inet->cork.fl.u.ip4; 75 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 76 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 77 IPPROTO_DCCP, 78 orig_sport, orig_dport, sk, true); 79 if (IS_ERR(rt)) 80 return PTR_ERR(rt); 81 82 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 83 ip_rt_put(rt); 84 return -ENETUNREACH; 85 } 86 87 if (inet_opt == NULL || !inet_opt->opt.srr) 88 daddr = fl4->daddr; 89 90 if (inet->inet_saddr == 0) 91 inet->inet_saddr = fl4->saddr; 92 inet->inet_rcv_saddr = inet->inet_saddr; 93 94 inet->inet_dport = usin->sin_port; 95 inet->inet_daddr = daddr; 96 97 inet_csk(sk)->icsk_ext_hdr_len = 0; 98 if (inet_opt) 99 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 100 /* 101 * Socket identity is still unknown (sport may be zero). 102 * However we set state to DCCP_REQUESTING and not releasing socket 103 * lock select source port, enter ourselves into the hash tables and 104 * complete initialization after this. 105 */ 106 dccp_set_state(sk, DCCP_REQUESTING); 107 err = inet_hash_connect(&dccp_death_row, sk); 108 if (err != 0) 109 goto failure; 110 111 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 112 inet->inet_sport, inet->inet_dport, sk); 113 if (IS_ERR(rt)) { 114 err = PTR_ERR(rt); 115 rt = NULL; 116 goto failure; 117 } 118 /* OK, now commit destination to socket. */ 119 sk_setup_caps(sk, &rt->dst); 120 121 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 122 inet->inet_daddr, 123 inet->inet_sport, 124 inet->inet_dport); 125 inet->inet_id = dp->dccps_iss ^ jiffies; 126 127 err = dccp_connect(sk); 128 rt = NULL; 129 if (err != 0) 130 goto failure; 131 out: 132 return err; 133 failure: 134 /* 135 * This unhashes the socket and releases the local port, if necessary. 136 */ 137 dccp_set_state(sk, DCCP_CLOSED); 138 ip_rt_put(rt); 139 sk->sk_route_caps = 0; 140 inet->inet_dport = 0; 141 goto out; 142 } 143 144 EXPORT_SYMBOL_GPL(dccp_v4_connect); 145 146 /* 147 * This routine does path mtu discovery as defined in RFC1191. 148 */ 149 static inline void dccp_do_pmtu_discovery(struct sock *sk, 150 const struct iphdr *iph, 151 u32 mtu) 152 { 153 struct dst_entry *dst; 154 const struct inet_sock *inet = inet_sk(sk); 155 const struct dccp_sock *dp = dccp_sk(sk); 156 157 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 158 * send out by Linux are always < 576bytes so they should go through 159 * unfragmented). 160 */ 161 if (sk->sk_state == DCCP_LISTEN) 162 return; 163 164 /* We don't check in the destentry if pmtu discovery is forbidden 165 * on this route. We just assume that no packet_to_big packets 166 * are send back when pmtu discovery is not active. 167 * There is a small race when the user changes this flag in the 168 * route, but I think that's acceptable. 169 */ 170 if ((dst = __sk_dst_check(sk, 0)) == NULL) 171 return; 172 173 dst->ops->update_pmtu(dst, mtu); 174 175 /* Something is about to be wrong... Remember soft error 176 * for the case, if this connection will not able to recover. 177 */ 178 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 179 sk->sk_err_soft = EMSGSIZE; 180 181 mtu = dst_mtu(dst); 182 183 if (inet->pmtudisc != IP_PMTUDISC_DONT && 184 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 185 dccp_sync_mss(sk, mtu); 186 187 /* 188 * From RFC 4340, sec. 14.1: 189 * 190 * DCCP-Sync packets are the best choice for upward 191 * probing, since DCCP-Sync probes do not risk application 192 * data loss. 193 */ 194 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 195 } /* else let the usual retransmit timer handle it */ 196 } 197 198 /* 199 * This routine is called by the ICMP module when it gets some sort of error 200 * condition. If err < 0 then the socket should be closed and the error 201 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 202 * After adjustment header points to the first 8 bytes of the tcp header. We 203 * need to find the appropriate port. 204 * 205 * The locking strategy used here is very "optimistic". When someone else 206 * accesses the socket the ICMP is just dropped and for some paths there is no 207 * check at all. A more general error queue to queue errors for later handling 208 * is probably better. 209 */ 210 static void dccp_v4_err(struct sk_buff *skb, u32 info) 211 { 212 const struct iphdr *iph = (struct iphdr *)skb->data; 213 const u8 offset = iph->ihl << 2; 214 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 215 struct dccp_sock *dp; 216 struct inet_sock *inet; 217 const int type = icmp_hdr(skb)->type; 218 const int code = icmp_hdr(skb)->code; 219 struct sock *sk; 220 __u64 seq; 221 int err; 222 struct net *net = dev_net(skb->dev); 223 224 if (skb->len < offset + sizeof(*dh) || 225 skb->len < offset + __dccp_basic_hdr_len(dh)) { 226 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 227 return; 228 } 229 230 sk = inet_lookup(net, &dccp_hashinfo, 231 iph->daddr, dh->dccph_dport, 232 iph->saddr, dh->dccph_sport, inet_iif(skb)); 233 if (sk == NULL) { 234 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 235 return; 236 } 237 238 if (sk->sk_state == DCCP_TIME_WAIT) { 239 inet_twsk_put(inet_twsk(sk)); 240 return; 241 } 242 243 bh_lock_sock(sk); 244 /* If too many ICMPs get dropped on busy 245 * servers this needs to be solved differently. 246 */ 247 if (sock_owned_by_user(sk)) 248 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 249 250 if (sk->sk_state == DCCP_CLOSED) 251 goto out; 252 253 dp = dccp_sk(sk); 254 seq = dccp_hdr_seq(dh); 255 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 256 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 257 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 258 goto out; 259 } 260 261 switch (type) { 262 case ICMP_SOURCE_QUENCH: 263 /* Just silently ignore these. */ 264 goto out; 265 case ICMP_PARAMETERPROB: 266 err = EPROTO; 267 break; 268 case ICMP_DEST_UNREACH: 269 if (code > NR_ICMP_UNREACH) 270 goto out; 271 272 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 273 if (!sock_owned_by_user(sk)) 274 dccp_do_pmtu_discovery(sk, iph, info); 275 goto out; 276 } 277 278 err = icmp_err_convert[code].errno; 279 break; 280 case ICMP_TIME_EXCEEDED: 281 err = EHOSTUNREACH; 282 break; 283 default: 284 goto out; 285 } 286 287 switch (sk->sk_state) { 288 struct request_sock *req , **prev; 289 case DCCP_LISTEN: 290 if (sock_owned_by_user(sk)) 291 goto out; 292 req = inet_csk_search_req(sk, &prev, dh->dccph_dport, 293 iph->daddr, iph->saddr); 294 if (!req) 295 goto out; 296 297 /* 298 * ICMPs are not backlogged, hence we cannot get an established 299 * socket here. 300 */ 301 WARN_ON(req->sk); 302 303 if (seq != dccp_rsk(req)->dreq_iss) { 304 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 305 goto out; 306 } 307 /* 308 * Still in RESPOND, just remove it silently. 309 * There is no good way to pass the error to the newly 310 * created socket, and POSIX does not want network 311 * errors returned from accept(). 312 */ 313 inet_csk_reqsk_queue_drop(sk, req, prev); 314 goto out; 315 316 case DCCP_REQUESTING: 317 case DCCP_RESPOND: 318 if (!sock_owned_by_user(sk)) { 319 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 320 sk->sk_err = err; 321 322 sk->sk_error_report(sk); 323 324 dccp_done(sk); 325 } else 326 sk->sk_err_soft = err; 327 goto out; 328 } 329 330 /* If we've already connected we will keep trying 331 * until we time out, or the user gives up. 332 * 333 * rfc1122 4.2.3.9 allows to consider as hard errors 334 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 335 * but it is obsoleted by pmtu discovery). 336 * 337 * Note, that in modern internet, where routing is unreliable 338 * and in each dark corner broken firewalls sit, sending random 339 * errors ordered by their masters even this two messages finally lose 340 * their original sense (even Linux sends invalid PORT_UNREACHs) 341 * 342 * Now we are in compliance with RFCs. 343 * --ANK (980905) 344 */ 345 346 inet = inet_sk(sk); 347 if (!sock_owned_by_user(sk) && inet->recverr) { 348 sk->sk_err = err; 349 sk->sk_error_report(sk); 350 } else /* Only an error on timeout */ 351 sk->sk_err_soft = err; 352 out: 353 bh_unlock_sock(sk); 354 sock_put(sk); 355 } 356 357 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 358 __be32 src, __be32 dst) 359 { 360 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 361 } 362 363 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 364 { 365 const struct inet_sock *inet = inet_sk(sk); 366 struct dccp_hdr *dh = dccp_hdr(skb); 367 368 dccp_csum_outgoing(skb); 369 dh->dccph_checksum = dccp_v4_csum_finish(skb, 370 inet->inet_saddr, 371 inet->inet_daddr); 372 } 373 374 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 375 376 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 377 { 378 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 379 ip_hdr(skb)->saddr, 380 dccp_hdr(skb)->dccph_dport, 381 dccp_hdr(skb)->dccph_sport); 382 } 383 384 /* 385 * The three way handshake has completed - we got a valid ACK or DATAACK - 386 * now create the new socket. 387 * 388 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 389 */ 390 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 391 struct request_sock *req, 392 struct dst_entry *dst) 393 { 394 struct inet_request_sock *ireq; 395 struct inet_sock *newinet; 396 struct sock *newsk; 397 398 if (sk_acceptq_is_full(sk)) 399 goto exit_overflow; 400 401 newsk = dccp_create_openreq_child(sk, req, skb); 402 if (newsk == NULL) 403 goto exit_nonewsk; 404 405 newinet = inet_sk(newsk); 406 ireq = inet_rsk(req); 407 newinet->inet_daddr = ireq->rmt_addr; 408 newinet->inet_rcv_saddr = ireq->loc_addr; 409 newinet->inet_saddr = ireq->loc_addr; 410 newinet->inet_opt = ireq->opt; 411 ireq->opt = NULL; 412 newinet->mc_index = inet_iif(skb); 413 newinet->mc_ttl = ip_hdr(skb)->ttl; 414 newinet->inet_id = jiffies; 415 416 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 417 goto put_and_exit; 418 419 sk_setup_caps(newsk, dst); 420 421 dccp_sync_mss(newsk, dst_mtu(dst)); 422 423 if (__inet_inherit_port(sk, newsk) < 0) 424 goto put_and_exit; 425 __inet_hash_nolisten(newsk, NULL); 426 427 return newsk; 428 429 exit_overflow: 430 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 431 exit_nonewsk: 432 dst_release(dst); 433 exit: 434 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 435 return NULL; 436 put_and_exit: 437 bh_unlock_sock(newsk); 438 sock_put(newsk); 439 goto exit; 440 } 441 442 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 443 444 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 445 { 446 const struct dccp_hdr *dh = dccp_hdr(skb); 447 const struct iphdr *iph = ip_hdr(skb); 448 struct sock *nsk; 449 struct request_sock **prev; 450 /* Find possible connection requests. */ 451 struct request_sock *req = inet_csk_search_req(sk, &prev, 452 dh->dccph_sport, 453 iph->saddr, iph->daddr); 454 if (req != NULL) 455 return dccp_check_req(sk, skb, req, prev); 456 457 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo, 458 iph->saddr, dh->dccph_sport, 459 iph->daddr, dh->dccph_dport, 460 inet_iif(skb)); 461 if (nsk != NULL) { 462 if (nsk->sk_state != DCCP_TIME_WAIT) { 463 bh_lock_sock(nsk); 464 return nsk; 465 } 466 inet_twsk_put(inet_twsk(nsk)); 467 return NULL; 468 } 469 470 return sk; 471 } 472 473 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 474 struct sk_buff *skb) 475 { 476 struct rtable *rt; 477 const struct iphdr *iph = ip_hdr(skb); 478 struct flowi4 fl4 = { 479 .flowi4_oif = skb_rtable(skb)->rt_iif, 480 .daddr = iph->saddr, 481 .saddr = iph->daddr, 482 .flowi4_tos = RT_CONN_FLAGS(sk), 483 .flowi4_proto = sk->sk_protocol, 484 .fl4_sport = dccp_hdr(skb)->dccph_dport, 485 .fl4_dport = dccp_hdr(skb)->dccph_sport, 486 }; 487 488 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 489 rt = ip_route_output_flow(net, &fl4, sk); 490 if (IS_ERR(rt)) { 491 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES); 492 return NULL; 493 } 494 495 return &rt->dst; 496 } 497 498 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req, 499 struct request_values *rv_unused) 500 { 501 int err = -1; 502 struct sk_buff *skb; 503 struct dst_entry *dst; 504 struct flowi4 fl4; 505 506 dst = inet_csk_route_req(sk, &fl4, req); 507 if (dst == NULL) 508 goto out; 509 510 skb = dccp_make_response(sk, dst, req); 511 if (skb != NULL) { 512 const struct inet_request_sock *ireq = inet_rsk(req); 513 struct dccp_hdr *dh = dccp_hdr(skb); 514 515 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr, 516 ireq->rmt_addr); 517 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 518 ireq->rmt_addr, 519 ireq->opt); 520 err = net_xmit_eval(err); 521 } 522 523 out: 524 dst_release(dst); 525 return err; 526 } 527 528 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 529 { 530 int err; 531 const struct iphdr *rxiph; 532 struct sk_buff *skb; 533 struct dst_entry *dst; 534 struct net *net = dev_net(skb_dst(rxskb)->dev); 535 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 536 537 /* Never send a reset in response to a reset. */ 538 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 539 return; 540 541 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 542 return; 543 544 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 545 if (dst == NULL) 546 return; 547 548 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 549 if (skb == NULL) 550 goto out; 551 552 rxiph = ip_hdr(rxskb); 553 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 554 rxiph->daddr); 555 skb_dst_set(skb, dst_clone(dst)); 556 557 bh_lock_sock(ctl_sk); 558 err = ip_build_and_send_pkt(skb, ctl_sk, 559 rxiph->daddr, rxiph->saddr, NULL); 560 bh_unlock_sock(ctl_sk); 561 562 if (net_xmit_eval(err) == 0) { 563 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 564 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 565 } 566 out: 567 dst_release(dst); 568 } 569 570 static void dccp_v4_reqsk_destructor(struct request_sock *req) 571 { 572 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 573 kfree(inet_rsk(req)->opt); 574 } 575 576 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 577 .family = PF_INET, 578 .obj_size = sizeof(struct dccp_request_sock), 579 .rtx_syn_ack = dccp_v4_send_response, 580 .send_ack = dccp_reqsk_send_ack, 581 .destructor = dccp_v4_reqsk_destructor, 582 .send_reset = dccp_v4_ctl_send_reset, 583 }; 584 585 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 586 { 587 struct inet_request_sock *ireq; 588 struct request_sock *req; 589 struct dccp_request_sock *dreq; 590 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 591 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 592 593 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 594 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 595 return 0; /* discard, don't send a reset here */ 596 597 if (dccp_bad_service_code(sk, service)) { 598 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 599 goto drop; 600 } 601 /* 602 * TW buckets are converted to open requests without 603 * limitations, they conserve resources and peer is 604 * evidently real one. 605 */ 606 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 607 if (inet_csk_reqsk_queue_is_full(sk)) 608 goto drop; 609 610 /* 611 * Accept backlog is full. If we have already queued enough 612 * of warm entries in syn queue, drop request. It is better than 613 * clogging syn queue with openreqs with exponentially increasing 614 * timeout. 615 */ 616 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 617 goto drop; 618 619 req = inet_reqsk_alloc(&dccp_request_sock_ops); 620 if (req == NULL) 621 goto drop; 622 623 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 624 goto drop_and_free; 625 626 dreq = dccp_rsk(req); 627 if (dccp_parse_options(sk, dreq, skb)) 628 goto drop_and_free; 629 630 if (security_inet_conn_request(sk, skb, req)) 631 goto drop_and_free; 632 633 ireq = inet_rsk(req); 634 ireq->loc_addr = ip_hdr(skb)->daddr; 635 ireq->rmt_addr = ip_hdr(skb)->saddr; 636 637 /* 638 * Step 3: Process LISTEN state 639 * 640 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 641 * 642 * In fact we defer setting S.GSR, S.SWL, S.SWH to 643 * dccp_create_openreq_child. 644 */ 645 dreq->dreq_isr = dcb->dccpd_seq; 646 dreq->dreq_iss = dccp_v4_init_sequence(skb); 647 dreq->dreq_service = service; 648 649 if (dccp_v4_send_response(sk, req, NULL)) 650 goto drop_and_free; 651 652 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 653 return 0; 654 655 drop_and_free: 656 reqsk_free(req); 657 drop: 658 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 659 return -1; 660 } 661 662 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 663 664 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 665 { 666 struct dccp_hdr *dh = dccp_hdr(skb); 667 668 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 669 if (dccp_rcv_established(sk, skb, dh, skb->len)) 670 goto reset; 671 return 0; 672 } 673 674 /* 675 * Step 3: Process LISTEN state 676 * If P.type == Request or P contains a valid Init Cookie option, 677 * (* Must scan the packet's options to check for Init 678 * Cookies. Only Init Cookies are processed here, 679 * however; other options are processed in Step 8. This 680 * scan need only be performed if the endpoint uses Init 681 * Cookies *) 682 * (* Generate a new socket and switch to that socket *) 683 * Set S := new socket for this port pair 684 * S.state = RESPOND 685 * Choose S.ISS (initial seqno) or set from Init Cookies 686 * Initialize S.GAR := S.ISS 687 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 688 * Continue with S.state == RESPOND 689 * (* A Response packet will be generated in Step 11 *) 690 * Otherwise, 691 * Generate Reset(No Connection) unless P.type == Reset 692 * Drop packet and return 693 * 694 * NOTE: the check for the packet types is done in 695 * dccp_rcv_state_process 696 */ 697 if (sk->sk_state == DCCP_LISTEN) { 698 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 699 700 if (nsk == NULL) 701 goto discard; 702 703 if (nsk != sk) { 704 if (dccp_child_process(sk, nsk, skb)) 705 goto reset; 706 return 0; 707 } 708 } 709 710 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 711 goto reset; 712 return 0; 713 714 reset: 715 dccp_v4_ctl_send_reset(sk, skb); 716 discard: 717 kfree_skb(skb); 718 return 0; 719 } 720 721 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 722 723 /** 724 * dccp_invalid_packet - check for malformed packets 725 * Implements RFC 4340, 8.5: Step 1: Check header basics 726 * Packets that fail these checks are ignored and do not receive Resets. 727 */ 728 int dccp_invalid_packet(struct sk_buff *skb) 729 { 730 const struct dccp_hdr *dh; 731 unsigned int cscov; 732 733 if (skb->pkt_type != PACKET_HOST) 734 return 1; 735 736 /* If the packet is shorter than 12 bytes, drop packet and return */ 737 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 738 DCCP_WARN("pskb_may_pull failed\n"); 739 return 1; 740 } 741 742 dh = dccp_hdr(skb); 743 744 /* If P.type is not understood, drop packet and return */ 745 if (dh->dccph_type >= DCCP_PKT_INVALID) { 746 DCCP_WARN("invalid packet type\n"); 747 return 1; 748 } 749 750 /* 751 * If P.Data Offset is too small for packet type, drop packet and return 752 */ 753 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 754 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 755 return 1; 756 } 757 /* 758 * If P.Data Offset is too too large for packet, drop packet and return 759 */ 760 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 761 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 762 return 1; 763 } 764 765 /* 766 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 767 * has short sequence numbers), drop packet and return 768 */ 769 if ((dh->dccph_type < DCCP_PKT_DATA || 770 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 771 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 772 dccp_packet_name(dh->dccph_type)); 773 return 1; 774 } 775 776 /* 777 * If P.CsCov is too large for the packet size, drop packet and return. 778 * This must come _before_ checksumming (not as RFC 4340 suggests). 779 */ 780 cscov = dccp_csum_coverage(skb); 781 if (cscov > skb->len) { 782 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 783 dh->dccph_cscov, skb->len); 784 return 1; 785 } 786 787 /* If header checksum is incorrect, drop packet and return. 788 * (This step is completed in the AF-dependent functions.) */ 789 skb->csum = skb_checksum(skb, 0, cscov, 0); 790 791 return 0; 792 } 793 794 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 795 796 /* this is called when real data arrives */ 797 static int dccp_v4_rcv(struct sk_buff *skb) 798 { 799 const struct dccp_hdr *dh; 800 const struct iphdr *iph; 801 struct sock *sk; 802 int min_cov; 803 804 /* Step 1: Check header basics */ 805 806 if (dccp_invalid_packet(skb)) 807 goto discard_it; 808 809 iph = ip_hdr(skb); 810 /* Step 1: If header checksum is incorrect, drop packet and return */ 811 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 812 DCCP_WARN("dropped packet with invalid checksum\n"); 813 goto discard_it; 814 } 815 816 dh = dccp_hdr(skb); 817 818 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 819 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 820 821 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 822 dccp_packet_name(dh->dccph_type), 823 &iph->saddr, ntohs(dh->dccph_sport), 824 &iph->daddr, ntohs(dh->dccph_dport), 825 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 826 827 if (dccp_packet_without_ack(skb)) { 828 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 829 dccp_pr_debug_cat("\n"); 830 } else { 831 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 832 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 833 DCCP_SKB_CB(skb)->dccpd_ack_seq); 834 } 835 836 /* Step 2: 837 * Look up flow ID in table and get corresponding socket */ 838 sk = __inet_lookup_skb(&dccp_hashinfo, skb, 839 dh->dccph_sport, dh->dccph_dport); 840 /* 841 * Step 2: 842 * If no socket ... 843 */ 844 if (sk == NULL) { 845 dccp_pr_debug("failed to look up flow ID in table and " 846 "get corresponding socket\n"); 847 goto no_dccp_socket; 848 } 849 850 /* 851 * Step 2: 852 * ... or S.state == TIMEWAIT, 853 * Generate Reset(No Connection) unless P.type == Reset 854 * Drop packet and return 855 */ 856 if (sk->sk_state == DCCP_TIME_WAIT) { 857 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 858 inet_twsk_put(inet_twsk(sk)); 859 goto no_dccp_socket; 860 } 861 862 /* 863 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 864 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 865 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 866 */ 867 min_cov = dccp_sk(sk)->dccps_pcrlen; 868 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 869 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 870 dh->dccph_cscov, min_cov); 871 /* FIXME: "Such packets SHOULD be reported using Data Dropped 872 * options (Section 11.7) with Drop Code 0, Protocol 873 * Constraints." */ 874 goto discard_and_relse; 875 } 876 877 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 878 goto discard_and_relse; 879 nf_reset(skb); 880 881 return sk_receive_skb(sk, skb, 1); 882 883 no_dccp_socket: 884 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 885 goto discard_it; 886 /* 887 * Step 2: 888 * If no socket ... 889 * Generate Reset(No Connection) unless P.type == Reset 890 * Drop packet and return 891 */ 892 if (dh->dccph_type != DCCP_PKT_RESET) { 893 DCCP_SKB_CB(skb)->dccpd_reset_code = 894 DCCP_RESET_CODE_NO_CONNECTION; 895 dccp_v4_ctl_send_reset(sk, skb); 896 } 897 898 discard_it: 899 kfree_skb(skb); 900 return 0; 901 902 discard_and_relse: 903 sock_put(sk); 904 goto discard_it; 905 } 906 907 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 908 .queue_xmit = ip_queue_xmit, 909 .send_check = dccp_v4_send_check, 910 .rebuild_header = inet_sk_rebuild_header, 911 .conn_request = dccp_v4_conn_request, 912 .syn_recv_sock = dccp_v4_request_recv_sock, 913 .net_header_len = sizeof(struct iphdr), 914 .setsockopt = ip_setsockopt, 915 .getsockopt = ip_getsockopt, 916 .addr2sockaddr = inet_csk_addr2sockaddr, 917 .sockaddr_len = sizeof(struct sockaddr_in), 918 .bind_conflict = inet_csk_bind_conflict, 919 #ifdef CONFIG_COMPAT 920 .compat_setsockopt = compat_ip_setsockopt, 921 .compat_getsockopt = compat_ip_getsockopt, 922 #endif 923 }; 924 925 static int dccp_v4_init_sock(struct sock *sk) 926 { 927 static __u8 dccp_v4_ctl_sock_initialized; 928 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 929 930 if (err == 0) { 931 if (unlikely(!dccp_v4_ctl_sock_initialized)) 932 dccp_v4_ctl_sock_initialized = 1; 933 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 934 } 935 936 return err; 937 } 938 939 static struct timewait_sock_ops dccp_timewait_sock_ops = { 940 .twsk_obj_size = sizeof(struct inet_timewait_sock), 941 }; 942 943 static struct proto dccp_v4_prot = { 944 .name = "DCCP", 945 .owner = THIS_MODULE, 946 .close = dccp_close, 947 .connect = dccp_v4_connect, 948 .disconnect = dccp_disconnect, 949 .ioctl = dccp_ioctl, 950 .init = dccp_v4_init_sock, 951 .setsockopt = dccp_setsockopt, 952 .getsockopt = dccp_getsockopt, 953 .sendmsg = dccp_sendmsg, 954 .recvmsg = dccp_recvmsg, 955 .backlog_rcv = dccp_v4_do_rcv, 956 .hash = inet_hash, 957 .unhash = inet_unhash, 958 .accept = inet_csk_accept, 959 .get_port = inet_csk_get_port, 960 .shutdown = dccp_shutdown, 961 .destroy = dccp_destroy_sock, 962 .orphan_count = &dccp_orphan_count, 963 .max_header = MAX_DCCP_HEADER, 964 .obj_size = sizeof(struct dccp_sock), 965 .slab_flags = SLAB_DESTROY_BY_RCU, 966 .rsk_prot = &dccp_request_sock_ops, 967 .twsk_prot = &dccp_timewait_sock_ops, 968 .h.hashinfo = &dccp_hashinfo, 969 #ifdef CONFIG_COMPAT 970 .compat_setsockopt = compat_dccp_setsockopt, 971 .compat_getsockopt = compat_dccp_getsockopt, 972 #endif 973 }; 974 975 static const struct net_protocol dccp_v4_protocol = { 976 .handler = dccp_v4_rcv, 977 .err_handler = dccp_v4_err, 978 .no_policy = 1, 979 .netns_ok = 1, 980 }; 981 982 static const struct proto_ops inet_dccp_ops = { 983 .family = PF_INET, 984 .owner = THIS_MODULE, 985 .release = inet_release, 986 .bind = inet_bind, 987 .connect = inet_stream_connect, 988 .socketpair = sock_no_socketpair, 989 .accept = inet_accept, 990 .getname = inet_getname, 991 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 992 .poll = dccp_poll, 993 .ioctl = inet_ioctl, 994 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 995 .listen = inet_dccp_listen, 996 .shutdown = inet_shutdown, 997 .setsockopt = sock_common_setsockopt, 998 .getsockopt = sock_common_getsockopt, 999 .sendmsg = inet_sendmsg, 1000 .recvmsg = sock_common_recvmsg, 1001 .mmap = sock_no_mmap, 1002 .sendpage = sock_no_sendpage, 1003 #ifdef CONFIG_COMPAT 1004 .compat_setsockopt = compat_sock_common_setsockopt, 1005 .compat_getsockopt = compat_sock_common_getsockopt, 1006 #endif 1007 }; 1008 1009 static struct inet_protosw dccp_v4_protosw = { 1010 .type = SOCK_DCCP, 1011 .protocol = IPPROTO_DCCP, 1012 .prot = &dccp_v4_prot, 1013 .ops = &inet_dccp_ops, 1014 .no_check = 0, 1015 .flags = INET_PROTOSW_ICSK, 1016 }; 1017 1018 static int __net_init dccp_v4_init_net(struct net *net) 1019 { 1020 if (dccp_hashinfo.bhash == NULL) 1021 return -ESOCKTNOSUPPORT; 1022 1023 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1024 SOCK_DCCP, IPPROTO_DCCP, net); 1025 } 1026 1027 static void __net_exit dccp_v4_exit_net(struct net *net) 1028 { 1029 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1030 } 1031 1032 static struct pernet_operations dccp_v4_ops = { 1033 .init = dccp_v4_init_net, 1034 .exit = dccp_v4_exit_net, 1035 }; 1036 1037 static int __init dccp_v4_init(void) 1038 { 1039 int err = proto_register(&dccp_v4_prot, 1); 1040 1041 if (err != 0) 1042 goto out; 1043 1044 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1045 if (err != 0) 1046 goto out_proto_unregister; 1047 1048 inet_register_protosw(&dccp_v4_protosw); 1049 1050 err = register_pernet_subsys(&dccp_v4_ops); 1051 if (err) 1052 goto out_destroy_ctl_sock; 1053 out: 1054 return err; 1055 out_destroy_ctl_sock: 1056 inet_unregister_protosw(&dccp_v4_protosw); 1057 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1058 out_proto_unregister: 1059 proto_unregister(&dccp_v4_prot); 1060 goto out; 1061 } 1062 1063 static void __exit dccp_v4_exit(void) 1064 { 1065 unregister_pernet_subsys(&dccp_v4_ops); 1066 inet_unregister_protosw(&dccp_v4_protosw); 1067 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1068 proto_unregister(&dccp_v4_prot); 1069 } 1070 1071 module_init(dccp_v4_init); 1072 module_exit(dccp_v4_exit); 1073 1074 /* 1075 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1076 * values directly, Also cover the case where the protocol is not specified, 1077 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1078 */ 1079 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1080 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1081 MODULE_LICENSE("GPL"); 1082 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1083 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1084