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); 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 sk_rcv_saddr_set(sk, inet->inet_saddr); 93 inet->inet_dport = usin->sin_port; 94 sk_daddr_set(sk, 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 err = PTR_ERR(rt); 114 rt = NULL; 115 goto failure; 116 } 117 /* OK, now commit destination to socket. */ 118 sk_setup_caps(sk, &rt->dst); 119 120 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 121 inet->inet_daddr, 122 inet->inet_sport, 123 inet->inet_dport); 124 inet->inet_id = dp->dccps_iss ^ jiffies; 125 126 err = dccp_connect(sk); 127 rt = NULL; 128 if (err != 0) 129 goto failure; 130 out: 131 return err; 132 failure: 133 /* 134 * This unhashes the socket and releases the local port, if necessary. 135 */ 136 dccp_set_state(sk, DCCP_CLOSED); 137 ip_rt_put(rt); 138 sk->sk_route_caps = 0; 139 inet->inet_dport = 0; 140 goto out; 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 dst = inet_csk_update_pmtu(sk, mtu); 163 if (!dst) 164 return; 165 166 /* Something is about to be wrong... Remember soft error 167 * for the case, if this connection will not able to recover. 168 */ 169 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 170 sk->sk_err_soft = EMSGSIZE; 171 172 mtu = dst_mtu(dst); 173 174 if (inet->pmtudisc != IP_PMTUDISC_DONT && 175 ip_sk_accept_pmtu(sk) && 176 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 177 dccp_sync_mss(sk, mtu); 178 179 /* 180 * From RFC 4340, sec. 14.1: 181 * 182 * DCCP-Sync packets are the best choice for upward 183 * probing, since DCCP-Sync probes do not risk application 184 * data loss. 185 */ 186 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 187 } /* else let the usual retransmit timer handle it */ 188 } 189 190 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 191 { 192 struct dst_entry *dst = __sk_dst_check(sk, 0); 193 194 if (dst) 195 dst->ops->redirect(dst, sk, skb); 196 } 197 198 void dccp_req_err(struct sock *sk, u64 seq) 199 { 200 struct request_sock *req = inet_reqsk(sk); 201 struct net *net = sock_net(sk); 202 203 /* 204 * ICMPs are not backlogged, hence we cannot get an established 205 * socket here. 206 */ 207 WARN_ON(req->sk); 208 209 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 210 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 211 reqsk_put(req); 212 } else { 213 /* 214 * Still in RESPOND, just remove it silently. 215 * There is no good way to pass the error to the newly 216 * created socket, and POSIX does not want network 217 * errors returned from accept(). 218 */ 219 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 220 } 221 } 222 EXPORT_SYMBOL(dccp_req_err); 223 224 /* 225 * This routine is called by the ICMP module when it gets some sort of error 226 * condition. If err < 0 then the socket should be closed and the error 227 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 228 * After adjustment header points to the first 8 bytes of the tcp header. We 229 * need to find the appropriate port. 230 * 231 * The locking strategy used here is very "optimistic". When someone else 232 * accesses the socket the ICMP is just dropped and for some paths there is no 233 * check at all. A more general error queue to queue errors for later handling 234 * is probably better. 235 */ 236 static void dccp_v4_err(struct sk_buff *skb, u32 info) 237 { 238 const struct iphdr *iph = (struct iphdr *)skb->data; 239 const u8 offset = iph->ihl << 2; 240 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 241 struct dccp_sock *dp; 242 struct inet_sock *inet; 243 const int type = icmp_hdr(skb)->type; 244 const int code = icmp_hdr(skb)->code; 245 struct sock *sk; 246 __u64 seq; 247 int err; 248 struct net *net = dev_net(skb->dev); 249 250 if (skb->len < offset + sizeof(*dh) || 251 skb->len < offset + __dccp_basic_hdr_len(dh)) { 252 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 253 return; 254 } 255 256 sk = __inet_lookup_established(net, &dccp_hashinfo, 257 iph->daddr, dh->dccph_dport, 258 iph->saddr, ntohs(dh->dccph_sport), 259 inet_iif(skb)); 260 if (!sk) { 261 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 262 return; 263 } 264 265 if (sk->sk_state == DCCP_TIME_WAIT) { 266 inet_twsk_put(inet_twsk(sk)); 267 return; 268 } 269 seq = dccp_hdr_seq(dh); 270 if (sk->sk_state == DCCP_NEW_SYN_RECV) 271 return dccp_req_err(sk, seq); 272 273 bh_lock_sock(sk); 274 /* If too many ICMPs get dropped on busy 275 * servers this needs to be solved differently. 276 */ 277 if (sock_owned_by_user(sk)) 278 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 279 280 if (sk->sk_state == DCCP_CLOSED) 281 goto out; 282 283 dp = dccp_sk(sk); 284 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 285 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 286 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 287 goto out; 288 } 289 290 switch (type) { 291 case ICMP_REDIRECT: 292 dccp_do_redirect(skb, sk); 293 goto out; 294 case ICMP_SOURCE_QUENCH: 295 /* Just silently ignore these. */ 296 goto out; 297 case ICMP_PARAMETERPROB: 298 err = EPROTO; 299 break; 300 case ICMP_DEST_UNREACH: 301 if (code > NR_ICMP_UNREACH) 302 goto out; 303 304 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 305 if (!sock_owned_by_user(sk)) 306 dccp_do_pmtu_discovery(sk, iph, info); 307 goto out; 308 } 309 310 err = icmp_err_convert[code].errno; 311 break; 312 case ICMP_TIME_EXCEEDED: 313 err = EHOSTUNREACH; 314 break; 315 default: 316 goto out; 317 } 318 319 switch (sk->sk_state) { 320 case DCCP_REQUESTING: 321 case DCCP_RESPOND: 322 if (!sock_owned_by_user(sk)) { 323 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 324 sk->sk_err = err; 325 326 sk->sk_error_report(sk); 327 328 dccp_done(sk); 329 } else 330 sk->sk_err_soft = err; 331 goto out; 332 } 333 334 /* If we've already connected we will keep trying 335 * until we time out, or the user gives up. 336 * 337 * rfc1122 4.2.3.9 allows to consider as hard errors 338 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 339 * but it is obsoleted by pmtu discovery). 340 * 341 * Note, that in modern internet, where routing is unreliable 342 * and in each dark corner broken firewalls sit, sending random 343 * errors ordered by their masters even this two messages finally lose 344 * their original sense (even Linux sends invalid PORT_UNREACHs) 345 * 346 * Now we are in compliance with RFCs. 347 * --ANK (980905) 348 */ 349 350 inet = inet_sk(sk); 351 if (!sock_owned_by_user(sk) && inet->recverr) { 352 sk->sk_err = err; 353 sk->sk_error_report(sk); 354 } else /* Only an error on timeout */ 355 sk->sk_err_soft = err; 356 out: 357 bh_unlock_sock(sk); 358 sock_put(sk); 359 } 360 361 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 362 __be32 src, __be32 dst) 363 { 364 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 365 } 366 367 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 368 { 369 const struct inet_sock *inet = inet_sk(sk); 370 struct dccp_hdr *dh = dccp_hdr(skb); 371 372 dccp_csum_outgoing(skb); 373 dh->dccph_checksum = dccp_v4_csum_finish(skb, 374 inet->inet_saddr, 375 inet->inet_daddr); 376 } 377 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 378 379 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 380 { 381 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 382 ip_hdr(skb)->saddr, 383 dccp_hdr(skb)->dccph_dport, 384 dccp_hdr(skb)->dccph_sport); 385 } 386 387 /* 388 * The three way handshake has completed - we got a valid ACK or DATAACK - 389 * now create the new socket. 390 * 391 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 392 */ 393 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 394 struct request_sock *req, 395 struct dst_entry *dst) 396 { 397 struct inet_request_sock *ireq; 398 struct inet_sock *newinet; 399 struct sock *newsk; 400 401 if (sk_acceptq_is_full(sk)) 402 goto exit_overflow; 403 404 newsk = dccp_create_openreq_child(sk, req, skb); 405 if (newsk == NULL) 406 goto exit_nonewsk; 407 408 newinet = inet_sk(newsk); 409 ireq = inet_rsk(req); 410 sk_daddr_set(newsk, ireq->ir_rmt_addr); 411 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 412 newinet->inet_saddr = ireq->ir_loc_addr; 413 newinet->inet_opt = ireq->opt; 414 ireq->opt = NULL; 415 newinet->mc_index = inet_iif(skb); 416 newinet->mc_ttl = ip_hdr(skb)->ttl; 417 newinet->inet_id = jiffies; 418 419 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 420 goto put_and_exit; 421 422 sk_setup_caps(newsk, dst); 423 424 dccp_sync_mss(newsk, dst_mtu(dst)); 425 426 if (__inet_inherit_port(sk, newsk) < 0) 427 goto put_and_exit; 428 __inet_hash_nolisten(newsk, NULL); 429 430 return newsk; 431 432 exit_overflow: 433 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 434 exit_nonewsk: 435 dst_release(dst); 436 exit: 437 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 438 return NULL; 439 put_and_exit: 440 inet_csk_prepare_forced_close(newsk); 441 dccp_done(newsk); 442 goto exit; 443 } 444 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 445 446 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 447 { 448 const struct dccp_hdr *dh = dccp_hdr(skb); 449 const struct iphdr *iph = ip_hdr(skb); 450 struct sock *nsk; 451 /* Find possible connection requests. */ 452 struct request_sock *req = inet_csk_search_req(sk, dh->dccph_sport, 453 iph->saddr, iph->daddr); 454 if (req) { 455 nsk = dccp_check_req(sk, skb, req); 456 if (!nsk) 457 reqsk_put(req); 458 return nsk; 459 } 460 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo, 461 iph->saddr, dh->dccph_sport, 462 iph->daddr, dh->dccph_dport, 463 inet_iif(skb)); 464 if (nsk != NULL) { 465 if (nsk->sk_state != DCCP_TIME_WAIT) { 466 bh_lock_sock(nsk); 467 return nsk; 468 } 469 inet_twsk_put(inet_twsk(nsk)); 470 return NULL; 471 } 472 473 return sk; 474 } 475 476 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 477 struct sk_buff *skb) 478 { 479 struct rtable *rt; 480 const struct iphdr *iph = ip_hdr(skb); 481 struct flowi4 fl4 = { 482 .flowi4_oif = inet_iif(skb), 483 .daddr = iph->saddr, 484 .saddr = iph->daddr, 485 .flowi4_tos = RT_CONN_FLAGS(sk), 486 .flowi4_proto = sk->sk_protocol, 487 .fl4_sport = dccp_hdr(skb)->dccph_dport, 488 .fl4_dport = dccp_hdr(skb)->dccph_sport, 489 }; 490 491 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 492 rt = ip_route_output_flow(net, &fl4, sk); 493 if (IS_ERR(rt)) { 494 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES); 495 return NULL; 496 } 497 498 return &rt->dst; 499 } 500 501 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req) 502 { 503 int err = -1; 504 struct sk_buff *skb; 505 struct dst_entry *dst; 506 struct flowi4 fl4; 507 508 dst = inet_csk_route_req(sk, &fl4, req); 509 if (dst == NULL) 510 goto out; 511 512 skb = dccp_make_response(sk, dst, req); 513 if (skb != NULL) { 514 const struct inet_request_sock *ireq = inet_rsk(req); 515 struct dccp_hdr *dh = dccp_hdr(skb); 516 517 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 518 ireq->ir_rmt_addr); 519 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 520 ireq->ir_rmt_addr, 521 ireq->opt); 522 err = net_xmit_eval(err); 523 } 524 525 out: 526 dst_release(dst); 527 return err; 528 } 529 530 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 531 { 532 int err; 533 const struct iphdr *rxiph; 534 struct sk_buff *skb; 535 struct dst_entry *dst; 536 struct net *net = dev_net(skb_dst(rxskb)->dev); 537 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 538 539 /* Never send a reset in response to a reset. */ 540 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 541 return; 542 543 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 544 return; 545 546 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 547 if (dst == NULL) 548 return; 549 550 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 551 if (skb == NULL) 552 goto out; 553 554 rxiph = ip_hdr(rxskb); 555 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 556 rxiph->daddr); 557 skb_dst_set(skb, dst_clone(dst)); 558 559 bh_lock_sock(ctl_sk); 560 err = ip_build_and_send_pkt(skb, ctl_sk, 561 rxiph->daddr, rxiph->saddr, NULL); 562 bh_unlock_sock(ctl_sk); 563 564 if (net_xmit_eval(err) == 0) { 565 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 566 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 567 } 568 out: 569 dst_release(dst); 570 } 571 572 static void dccp_v4_reqsk_destructor(struct request_sock *req) 573 { 574 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 575 kfree(inet_rsk(req)->opt); 576 } 577 578 void dccp_syn_ack_timeout(const struct request_sock *req) 579 { 580 } 581 EXPORT_SYMBOL(dccp_syn_ack_timeout); 582 583 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 584 .family = PF_INET, 585 .obj_size = sizeof(struct dccp_request_sock), 586 .rtx_syn_ack = dccp_v4_send_response, 587 .send_ack = dccp_reqsk_send_ack, 588 .destructor = dccp_v4_reqsk_destructor, 589 .send_reset = dccp_v4_ctl_send_reset, 590 .syn_ack_timeout = dccp_syn_ack_timeout, 591 }; 592 593 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 594 { 595 struct inet_request_sock *ireq; 596 struct request_sock *req; 597 struct dccp_request_sock *dreq; 598 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 599 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 600 601 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 602 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 603 return 0; /* discard, don't send a reset here */ 604 605 if (dccp_bad_service_code(sk, service)) { 606 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 607 goto drop; 608 } 609 /* 610 * TW buckets are converted to open requests without 611 * limitations, they conserve resources and peer is 612 * evidently real one. 613 */ 614 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 615 if (inet_csk_reqsk_queue_is_full(sk)) 616 goto drop; 617 618 /* 619 * Accept backlog is full. If we have already queued enough 620 * of warm entries in syn queue, drop request. It is better than 621 * clogging syn queue with openreqs with exponentially increasing 622 * timeout. 623 */ 624 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 625 goto drop; 626 627 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk); 628 if (req == NULL) 629 goto drop; 630 631 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 632 goto drop_and_free; 633 634 dreq = dccp_rsk(req); 635 if (dccp_parse_options(sk, dreq, skb)) 636 goto drop_and_free; 637 638 if (security_inet_conn_request(sk, skb, req)) 639 goto drop_and_free; 640 641 ireq = inet_rsk(req); 642 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 643 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 644 ireq->ireq_family = AF_INET; 645 ireq->ir_iif = sk->sk_bound_dev_if; 646 647 /* 648 * Step 3: Process LISTEN state 649 * 650 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 651 * 652 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 653 */ 654 dreq->dreq_isr = dcb->dccpd_seq; 655 dreq->dreq_gsr = dreq->dreq_isr; 656 dreq->dreq_iss = dccp_v4_init_sequence(skb); 657 dreq->dreq_gss = dreq->dreq_iss; 658 dreq->dreq_service = service; 659 660 if (dccp_v4_send_response(sk, req)) 661 goto drop_and_free; 662 663 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 664 return 0; 665 666 drop_and_free: 667 reqsk_free(req); 668 drop: 669 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 670 return -1; 671 } 672 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 673 674 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 675 { 676 struct dccp_hdr *dh = dccp_hdr(skb); 677 678 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 679 if (dccp_rcv_established(sk, skb, dh, skb->len)) 680 goto reset; 681 return 0; 682 } 683 684 /* 685 * Step 3: Process LISTEN state 686 * If P.type == Request or P contains a valid Init Cookie option, 687 * (* Must scan the packet's options to check for Init 688 * Cookies. Only Init Cookies are processed here, 689 * however; other options are processed in Step 8. This 690 * scan need only be performed if the endpoint uses Init 691 * Cookies *) 692 * (* Generate a new socket and switch to that socket *) 693 * Set S := new socket for this port pair 694 * S.state = RESPOND 695 * Choose S.ISS (initial seqno) or set from Init Cookies 696 * Initialize S.GAR := S.ISS 697 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 698 * Continue with S.state == RESPOND 699 * (* A Response packet will be generated in Step 11 *) 700 * Otherwise, 701 * Generate Reset(No Connection) unless P.type == Reset 702 * Drop packet and return 703 * 704 * NOTE: the check for the packet types is done in 705 * dccp_rcv_state_process 706 */ 707 if (sk->sk_state == DCCP_LISTEN) { 708 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 709 710 if (nsk == NULL) 711 goto discard; 712 713 if (nsk != sk) { 714 if (dccp_child_process(sk, nsk, skb)) 715 goto reset; 716 return 0; 717 } 718 } 719 720 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 721 goto reset; 722 return 0; 723 724 reset: 725 dccp_v4_ctl_send_reset(sk, skb); 726 discard: 727 kfree_skb(skb); 728 return 0; 729 } 730 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 731 732 /** 733 * dccp_invalid_packet - check for malformed packets 734 * Implements RFC 4340, 8.5: Step 1: Check header basics 735 * Packets that fail these checks are ignored and do not receive Resets. 736 */ 737 int dccp_invalid_packet(struct sk_buff *skb) 738 { 739 const struct dccp_hdr *dh; 740 unsigned int cscov; 741 742 if (skb->pkt_type != PACKET_HOST) 743 return 1; 744 745 /* If the packet is shorter than 12 bytes, drop packet and return */ 746 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 747 DCCP_WARN("pskb_may_pull failed\n"); 748 return 1; 749 } 750 751 dh = dccp_hdr(skb); 752 753 /* If P.type is not understood, drop packet and return */ 754 if (dh->dccph_type >= DCCP_PKT_INVALID) { 755 DCCP_WARN("invalid packet type\n"); 756 return 1; 757 } 758 759 /* 760 * If P.Data Offset is too small for packet type, drop packet and return 761 */ 762 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 763 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 764 return 1; 765 } 766 /* 767 * If P.Data Offset is too too large for packet, drop packet and return 768 */ 769 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 770 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 771 return 1; 772 } 773 774 /* 775 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 776 * has short sequence numbers), drop packet and return 777 */ 778 if ((dh->dccph_type < DCCP_PKT_DATA || 779 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 780 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 781 dccp_packet_name(dh->dccph_type)); 782 return 1; 783 } 784 785 /* 786 * If P.CsCov is too large for the packet size, drop packet and return. 787 * This must come _before_ checksumming (not as RFC 4340 suggests). 788 */ 789 cscov = dccp_csum_coverage(skb); 790 if (cscov > skb->len) { 791 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 792 dh->dccph_cscov, skb->len); 793 return 1; 794 } 795 796 /* If header checksum is incorrect, drop packet and return. 797 * (This step is completed in the AF-dependent functions.) */ 798 skb->csum = skb_checksum(skb, 0, cscov, 0); 799 800 return 0; 801 } 802 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 803 804 /* this is called when real data arrives */ 805 static int dccp_v4_rcv(struct sk_buff *skb) 806 { 807 const struct dccp_hdr *dh; 808 const struct iphdr *iph; 809 struct sock *sk; 810 int min_cov; 811 812 /* Step 1: Check header basics */ 813 814 if (dccp_invalid_packet(skb)) 815 goto discard_it; 816 817 iph = ip_hdr(skb); 818 /* Step 1: If header checksum is incorrect, drop packet and return */ 819 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 820 DCCP_WARN("dropped packet with invalid checksum\n"); 821 goto discard_it; 822 } 823 824 dh = dccp_hdr(skb); 825 826 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 827 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 828 829 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 830 dccp_packet_name(dh->dccph_type), 831 &iph->saddr, ntohs(dh->dccph_sport), 832 &iph->daddr, ntohs(dh->dccph_dport), 833 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 834 835 if (dccp_packet_without_ack(skb)) { 836 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 837 dccp_pr_debug_cat("\n"); 838 } else { 839 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 840 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 841 DCCP_SKB_CB(skb)->dccpd_ack_seq); 842 } 843 844 /* Step 2: 845 * Look up flow ID in table and get corresponding socket */ 846 sk = __inet_lookup_skb(&dccp_hashinfo, skb, 847 dh->dccph_sport, dh->dccph_dport); 848 /* 849 * Step 2: 850 * If no socket ... 851 */ 852 if (sk == NULL) { 853 dccp_pr_debug("failed to look up flow ID in table and " 854 "get corresponding socket\n"); 855 goto no_dccp_socket; 856 } 857 858 /* 859 * Step 2: 860 * ... or S.state == TIMEWAIT, 861 * Generate Reset(No Connection) unless P.type == Reset 862 * Drop packet and return 863 */ 864 if (sk->sk_state == DCCP_TIME_WAIT) { 865 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 866 inet_twsk_put(inet_twsk(sk)); 867 goto no_dccp_socket; 868 } 869 870 /* 871 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 872 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 873 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 874 */ 875 min_cov = dccp_sk(sk)->dccps_pcrlen; 876 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 877 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 878 dh->dccph_cscov, min_cov); 879 /* FIXME: "Such packets SHOULD be reported using Data Dropped 880 * options (Section 11.7) with Drop Code 0, Protocol 881 * Constraints." */ 882 goto discard_and_relse; 883 } 884 885 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 886 goto discard_and_relse; 887 nf_reset(skb); 888 889 return sk_receive_skb(sk, skb, 1); 890 891 no_dccp_socket: 892 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 893 goto discard_it; 894 /* 895 * Step 2: 896 * If no socket ... 897 * Generate Reset(No Connection) unless P.type == Reset 898 * Drop packet and return 899 */ 900 if (dh->dccph_type != DCCP_PKT_RESET) { 901 DCCP_SKB_CB(skb)->dccpd_reset_code = 902 DCCP_RESET_CODE_NO_CONNECTION; 903 dccp_v4_ctl_send_reset(sk, skb); 904 } 905 906 discard_it: 907 kfree_skb(skb); 908 return 0; 909 910 discard_and_relse: 911 sock_put(sk); 912 goto discard_it; 913 } 914 915 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 916 .queue_xmit = ip_queue_xmit, 917 .send_check = dccp_v4_send_check, 918 .rebuild_header = inet_sk_rebuild_header, 919 .conn_request = dccp_v4_conn_request, 920 .syn_recv_sock = dccp_v4_request_recv_sock, 921 .net_header_len = sizeof(struct iphdr), 922 .setsockopt = ip_setsockopt, 923 .getsockopt = ip_getsockopt, 924 .addr2sockaddr = inet_csk_addr2sockaddr, 925 .sockaddr_len = sizeof(struct sockaddr_in), 926 .bind_conflict = inet_csk_bind_conflict, 927 #ifdef CONFIG_COMPAT 928 .compat_setsockopt = compat_ip_setsockopt, 929 .compat_getsockopt = compat_ip_getsockopt, 930 #endif 931 }; 932 933 static int dccp_v4_init_sock(struct sock *sk) 934 { 935 static __u8 dccp_v4_ctl_sock_initialized; 936 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 937 938 if (err == 0) { 939 if (unlikely(!dccp_v4_ctl_sock_initialized)) 940 dccp_v4_ctl_sock_initialized = 1; 941 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 942 } 943 944 return err; 945 } 946 947 static struct timewait_sock_ops dccp_timewait_sock_ops = { 948 .twsk_obj_size = sizeof(struct inet_timewait_sock), 949 }; 950 951 static struct proto dccp_v4_prot = { 952 .name = "DCCP", 953 .owner = THIS_MODULE, 954 .close = dccp_close, 955 .connect = dccp_v4_connect, 956 .disconnect = dccp_disconnect, 957 .ioctl = dccp_ioctl, 958 .init = dccp_v4_init_sock, 959 .setsockopt = dccp_setsockopt, 960 .getsockopt = dccp_getsockopt, 961 .sendmsg = dccp_sendmsg, 962 .recvmsg = dccp_recvmsg, 963 .backlog_rcv = dccp_v4_do_rcv, 964 .hash = inet_hash, 965 .unhash = inet_unhash, 966 .accept = inet_csk_accept, 967 .get_port = inet_csk_get_port, 968 .shutdown = dccp_shutdown, 969 .destroy = dccp_destroy_sock, 970 .orphan_count = &dccp_orphan_count, 971 .max_header = MAX_DCCP_HEADER, 972 .obj_size = sizeof(struct dccp_sock), 973 .slab_flags = SLAB_DESTROY_BY_RCU, 974 .rsk_prot = &dccp_request_sock_ops, 975 .twsk_prot = &dccp_timewait_sock_ops, 976 .h.hashinfo = &dccp_hashinfo, 977 #ifdef CONFIG_COMPAT 978 .compat_setsockopt = compat_dccp_setsockopt, 979 .compat_getsockopt = compat_dccp_getsockopt, 980 #endif 981 }; 982 983 static const struct net_protocol dccp_v4_protocol = { 984 .handler = dccp_v4_rcv, 985 .err_handler = dccp_v4_err, 986 .no_policy = 1, 987 .netns_ok = 1, 988 .icmp_strict_tag_validation = 1, 989 }; 990 991 static const struct proto_ops inet_dccp_ops = { 992 .family = PF_INET, 993 .owner = THIS_MODULE, 994 .release = inet_release, 995 .bind = inet_bind, 996 .connect = inet_stream_connect, 997 .socketpair = sock_no_socketpair, 998 .accept = inet_accept, 999 .getname = inet_getname, 1000 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1001 .poll = dccp_poll, 1002 .ioctl = inet_ioctl, 1003 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1004 .listen = inet_dccp_listen, 1005 .shutdown = inet_shutdown, 1006 .setsockopt = sock_common_setsockopt, 1007 .getsockopt = sock_common_getsockopt, 1008 .sendmsg = inet_sendmsg, 1009 .recvmsg = sock_common_recvmsg, 1010 .mmap = sock_no_mmap, 1011 .sendpage = sock_no_sendpage, 1012 #ifdef CONFIG_COMPAT 1013 .compat_setsockopt = compat_sock_common_setsockopt, 1014 .compat_getsockopt = compat_sock_common_getsockopt, 1015 #endif 1016 }; 1017 1018 static struct inet_protosw dccp_v4_protosw = { 1019 .type = SOCK_DCCP, 1020 .protocol = IPPROTO_DCCP, 1021 .prot = &dccp_v4_prot, 1022 .ops = &inet_dccp_ops, 1023 .flags = INET_PROTOSW_ICSK, 1024 }; 1025 1026 static int __net_init dccp_v4_init_net(struct net *net) 1027 { 1028 if (dccp_hashinfo.bhash == NULL) 1029 return -ESOCKTNOSUPPORT; 1030 1031 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1032 SOCK_DCCP, IPPROTO_DCCP, net); 1033 } 1034 1035 static void __net_exit dccp_v4_exit_net(struct net *net) 1036 { 1037 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1038 } 1039 1040 static struct pernet_operations dccp_v4_ops = { 1041 .init = dccp_v4_init_net, 1042 .exit = dccp_v4_exit_net, 1043 }; 1044 1045 static int __init dccp_v4_init(void) 1046 { 1047 int err = proto_register(&dccp_v4_prot, 1); 1048 1049 if (err != 0) 1050 goto out; 1051 1052 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1053 if (err != 0) 1054 goto out_proto_unregister; 1055 1056 inet_register_protosw(&dccp_v4_protosw); 1057 1058 err = register_pernet_subsys(&dccp_v4_ops); 1059 if (err) 1060 goto out_destroy_ctl_sock; 1061 out: 1062 return err; 1063 out_destroy_ctl_sock: 1064 inet_unregister_protosw(&dccp_v4_protosw); 1065 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1066 out_proto_unregister: 1067 proto_unregister(&dccp_v4_prot); 1068 goto out; 1069 } 1070 1071 static void __exit dccp_v4_exit(void) 1072 { 1073 unregister_pernet_subsys(&dccp_v4_ops); 1074 inet_unregister_protosw(&dccp_v4_protosw); 1075 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1076 proto_unregister(&dccp_v4_prot); 1077 } 1078 1079 module_init(dccp_v4_init); 1080 module_exit(dccp_v4_exit); 1081 1082 /* 1083 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1084 * values directly, Also cover the case where the protocol is not specified, 1085 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1086 */ 1087 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1088 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1089 MODULE_LICENSE("GPL"); 1090 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1091 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1092