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 dst = inet_csk_update_pmtu(sk, mtu); 165 if (!dst) 166 return; 167 168 /* Something is about to be wrong... Remember soft error 169 * for the case, if this connection will not able to recover. 170 */ 171 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 172 sk->sk_err_soft = EMSGSIZE; 173 174 mtu = dst_mtu(dst); 175 176 if (inet->pmtudisc != IP_PMTUDISC_DONT && 177 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 178 dccp_sync_mss(sk, mtu); 179 180 /* 181 * From RFC 4340, sec. 14.1: 182 * 183 * DCCP-Sync packets are the best choice for upward 184 * probing, since DCCP-Sync probes do not risk application 185 * data loss. 186 */ 187 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 188 } /* else let the usual retransmit timer handle it */ 189 } 190 191 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 192 { 193 struct dst_entry *dst = __sk_dst_check(sk, 0); 194 195 if (dst) 196 dst->ops->redirect(dst, sk, skb); 197 } 198 199 /* 200 * This routine is called by the ICMP module when it gets some sort of error 201 * condition. If err < 0 then the socket should be closed and the error 202 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 203 * After adjustment header points to the first 8 bytes of the tcp header. We 204 * need to find the appropriate port. 205 * 206 * The locking strategy used here is very "optimistic". When someone else 207 * accesses the socket the ICMP is just dropped and for some paths there is no 208 * check at all. A more general error queue to queue errors for later handling 209 * is probably better. 210 */ 211 static void dccp_v4_err(struct sk_buff *skb, u32 info) 212 { 213 const struct iphdr *iph = (struct iphdr *)skb->data; 214 const u8 offset = iph->ihl << 2; 215 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 216 struct dccp_sock *dp; 217 struct inet_sock *inet; 218 const int type = icmp_hdr(skb)->type; 219 const int code = icmp_hdr(skb)->code; 220 struct sock *sk; 221 __u64 seq; 222 int err; 223 struct net *net = dev_net(skb->dev); 224 225 if (skb->len < offset + sizeof(*dh) || 226 skb->len < offset + __dccp_basic_hdr_len(dh)) { 227 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 228 return; 229 } 230 231 sk = inet_lookup(net, &dccp_hashinfo, 232 iph->daddr, dh->dccph_dport, 233 iph->saddr, dh->dccph_sport, inet_iif(skb)); 234 if (sk == NULL) { 235 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 236 return; 237 } 238 239 if (sk->sk_state == DCCP_TIME_WAIT) { 240 inet_twsk_put(inet_twsk(sk)); 241 return; 242 } 243 244 bh_lock_sock(sk); 245 /* If too many ICMPs get dropped on busy 246 * servers this needs to be solved differently. 247 */ 248 if (sock_owned_by_user(sk)) 249 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 250 251 if (sk->sk_state == DCCP_CLOSED) 252 goto out; 253 254 dp = dccp_sk(sk); 255 seq = dccp_hdr_seq(dh); 256 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 257 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 258 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 259 goto out; 260 } 261 262 switch (type) { 263 case ICMP_REDIRECT: 264 dccp_do_redirect(skb, sk); 265 goto out; 266 case ICMP_SOURCE_QUENCH: 267 /* Just silently ignore these. */ 268 goto out; 269 case ICMP_PARAMETERPROB: 270 err = EPROTO; 271 break; 272 case ICMP_DEST_UNREACH: 273 if (code > NR_ICMP_UNREACH) 274 goto out; 275 276 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 277 if (!sock_owned_by_user(sk)) 278 dccp_do_pmtu_discovery(sk, iph, info); 279 goto out; 280 } 281 282 err = icmp_err_convert[code].errno; 283 break; 284 case ICMP_TIME_EXCEEDED: 285 err = EHOSTUNREACH; 286 break; 287 default: 288 goto out; 289 } 290 291 switch (sk->sk_state) { 292 struct request_sock *req , **prev; 293 case DCCP_LISTEN: 294 if (sock_owned_by_user(sk)) 295 goto out; 296 req = inet_csk_search_req(sk, &prev, dh->dccph_dport, 297 iph->daddr, iph->saddr); 298 if (!req) 299 goto out; 300 301 /* 302 * ICMPs are not backlogged, hence we cannot get an established 303 * socket here. 304 */ 305 WARN_ON(req->sk); 306 307 if (!between48(seq, dccp_rsk(req)->dreq_iss, 308 dccp_rsk(req)->dreq_gss)) { 309 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 310 goto out; 311 } 312 /* 313 * Still in RESPOND, just remove it silently. 314 * There is no good way to pass the error to the newly 315 * created socket, and POSIX does not want network 316 * errors returned from accept(). 317 */ 318 inet_csk_reqsk_queue_drop(sk, req, prev); 319 goto out; 320 321 case DCCP_REQUESTING: 322 case DCCP_RESPOND: 323 if (!sock_owned_by_user(sk)) { 324 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 325 sk->sk_err = err; 326 327 sk->sk_error_report(sk); 328 329 dccp_done(sk); 330 } else 331 sk->sk_err_soft = err; 332 goto out; 333 } 334 335 /* If we've already connected we will keep trying 336 * until we time out, or the user gives up. 337 * 338 * rfc1122 4.2.3.9 allows to consider as hard errors 339 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 340 * but it is obsoleted by pmtu discovery). 341 * 342 * Note, that in modern internet, where routing is unreliable 343 * and in each dark corner broken firewalls sit, sending random 344 * errors ordered by their masters even this two messages finally lose 345 * their original sense (even Linux sends invalid PORT_UNREACHs) 346 * 347 * Now we are in compliance with RFCs. 348 * --ANK (980905) 349 */ 350 351 inet = inet_sk(sk); 352 if (!sock_owned_by_user(sk) && inet->recverr) { 353 sk->sk_err = err; 354 sk->sk_error_report(sk); 355 } else /* Only an error on timeout */ 356 sk->sk_err_soft = err; 357 out: 358 bh_unlock_sock(sk); 359 sock_put(sk); 360 } 361 362 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 363 __be32 src, __be32 dst) 364 { 365 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 366 } 367 368 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 369 { 370 const struct inet_sock *inet = inet_sk(sk); 371 struct dccp_hdr *dh = dccp_hdr(skb); 372 373 dccp_csum_outgoing(skb); 374 dh->dccph_checksum = dccp_v4_csum_finish(skb, 375 inet->inet_saddr, 376 inet->inet_daddr); 377 } 378 379 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 380 381 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 382 { 383 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 384 ip_hdr(skb)->saddr, 385 dccp_hdr(skb)->dccph_dport, 386 dccp_hdr(skb)->dccph_sport); 387 } 388 389 /* 390 * The three way handshake has completed - we got a valid ACK or DATAACK - 391 * now create the new socket. 392 * 393 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 394 */ 395 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 396 struct request_sock *req, 397 struct dst_entry *dst) 398 { 399 struct inet_request_sock *ireq; 400 struct inet_sock *newinet; 401 struct sock *newsk; 402 403 if (sk_acceptq_is_full(sk)) 404 goto exit_overflow; 405 406 newsk = dccp_create_openreq_child(sk, req, skb); 407 if (newsk == NULL) 408 goto exit_nonewsk; 409 410 newinet = inet_sk(newsk); 411 ireq = inet_rsk(req); 412 newinet->inet_daddr = ireq->rmt_addr; 413 newinet->inet_rcv_saddr = ireq->loc_addr; 414 newinet->inet_saddr = ireq->loc_addr; 415 newinet->inet_opt = ireq->opt; 416 ireq->opt = NULL; 417 newinet->mc_index = inet_iif(skb); 418 newinet->mc_ttl = ip_hdr(skb)->ttl; 419 newinet->inet_id = jiffies; 420 421 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 422 goto put_and_exit; 423 424 sk_setup_caps(newsk, dst); 425 426 dccp_sync_mss(newsk, dst_mtu(dst)); 427 428 if (__inet_inherit_port(sk, newsk) < 0) 429 goto put_and_exit; 430 __inet_hash_nolisten(newsk, NULL); 431 432 return newsk; 433 434 exit_overflow: 435 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 436 exit_nonewsk: 437 dst_release(dst); 438 exit: 439 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 440 return NULL; 441 put_and_exit: 442 inet_csk_prepare_forced_close(newsk); 443 dccp_done(newsk); 444 goto exit; 445 } 446 447 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 448 449 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 450 { 451 const struct dccp_hdr *dh = dccp_hdr(skb); 452 const struct iphdr *iph = ip_hdr(skb); 453 struct sock *nsk; 454 struct request_sock **prev; 455 /* Find possible connection requests. */ 456 struct request_sock *req = inet_csk_search_req(sk, &prev, 457 dh->dccph_sport, 458 iph->saddr, iph->daddr); 459 if (req != NULL) 460 return dccp_check_req(sk, skb, req, prev); 461 462 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo, 463 iph->saddr, dh->dccph_sport, 464 iph->daddr, dh->dccph_dport, 465 inet_iif(skb)); 466 if (nsk != NULL) { 467 if (nsk->sk_state != DCCP_TIME_WAIT) { 468 bh_lock_sock(nsk); 469 return nsk; 470 } 471 inet_twsk_put(inet_twsk(nsk)); 472 return NULL; 473 } 474 475 return sk; 476 } 477 478 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 479 struct sk_buff *skb) 480 { 481 struct rtable *rt; 482 const struct iphdr *iph = ip_hdr(skb); 483 struct flowi4 fl4 = { 484 .flowi4_oif = inet_iif(skb), 485 .daddr = iph->saddr, 486 .saddr = iph->daddr, 487 .flowi4_tos = RT_CONN_FLAGS(sk), 488 .flowi4_proto = sk->sk_protocol, 489 .fl4_sport = dccp_hdr(skb)->dccph_dport, 490 .fl4_dport = dccp_hdr(skb)->dccph_sport, 491 }; 492 493 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 494 rt = ip_route_output_flow(net, &fl4, sk); 495 if (IS_ERR(rt)) { 496 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES); 497 return NULL; 498 } 499 500 return &rt->dst; 501 } 502 503 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req) 504 { 505 int err = -1; 506 struct sk_buff *skb; 507 struct dst_entry *dst; 508 struct flowi4 fl4; 509 510 dst = inet_csk_route_req(sk, &fl4, req); 511 if (dst == NULL) 512 goto out; 513 514 skb = dccp_make_response(sk, dst, req); 515 if (skb != NULL) { 516 const struct inet_request_sock *ireq = inet_rsk(req); 517 struct dccp_hdr *dh = dccp_hdr(skb); 518 519 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr, 520 ireq->rmt_addr); 521 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 522 ireq->rmt_addr, 523 ireq->opt); 524 err = net_xmit_eval(err); 525 } 526 527 out: 528 dst_release(dst); 529 return err; 530 } 531 532 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 533 { 534 int err; 535 const struct iphdr *rxiph; 536 struct sk_buff *skb; 537 struct dst_entry *dst; 538 struct net *net = dev_net(skb_dst(rxskb)->dev); 539 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 540 541 /* Never send a reset in response to a reset. */ 542 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 543 return; 544 545 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 546 return; 547 548 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 549 if (dst == NULL) 550 return; 551 552 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 553 if (skb == NULL) 554 goto out; 555 556 rxiph = ip_hdr(rxskb); 557 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 558 rxiph->daddr); 559 skb_dst_set(skb, dst_clone(dst)); 560 561 bh_lock_sock(ctl_sk); 562 err = ip_build_and_send_pkt(skb, ctl_sk, 563 rxiph->daddr, rxiph->saddr, NULL); 564 bh_unlock_sock(ctl_sk); 565 566 if (net_xmit_eval(err) == 0) { 567 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 568 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 569 } 570 out: 571 dst_release(dst); 572 } 573 574 static void dccp_v4_reqsk_destructor(struct request_sock *req) 575 { 576 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 577 kfree(inet_rsk(req)->opt); 578 } 579 580 void dccp_syn_ack_timeout(struct sock *sk, struct request_sock *req) 581 { 582 } 583 EXPORT_SYMBOL(dccp_syn_ack_timeout); 584 585 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 586 .family = PF_INET, 587 .obj_size = sizeof(struct dccp_request_sock), 588 .rtx_syn_ack = dccp_v4_send_response, 589 .send_ack = dccp_reqsk_send_ack, 590 .destructor = dccp_v4_reqsk_destructor, 591 .send_reset = dccp_v4_ctl_send_reset, 592 .syn_ack_timeout = dccp_syn_ack_timeout, 593 }; 594 595 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 596 { 597 struct inet_request_sock *ireq; 598 struct request_sock *req; 599 struct dccp_request_sock *dreq; 600 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 601 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 602 603 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 604 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 605 return 0; /* discard, don't send a reset here */ 606 607 if (dccp_bad_service_code(sk, service)) { 608 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 609 goto drop; 610 } 611 /* 612 * TW buckets are converted to open requests without 613 * limitations, they conserve resources and peer is 614 * evidently real one. 615 */ 616 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 617 if (inet_csk_reqsk_queue_is_full(sk)) 618 goto drop; 619 620 /* 621 * Accept backlog is full. If we have already queued enough 622 * of warm entries in syn queue, drop request. It is better than 623 * clogging syn queue with openreqs with exponentially increasing 624 * timeout. 625 */ 626 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 627 goto drop; 628 629 req = inet_reqsk_alloc(&dccp_request_sock_ops); 630 if (req == NULL) 631 goto drop; 632 633 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 634 goto drop_and_free; 635 636 dreq = dccp_rsk(req); 637 if (dccp_parse_options(sk, dreq, skb)) 638 goto drop_and_free; 639 640 if (security_inet_conn_request(sk, skb, req)) 641 goto drop_and_free; 642 643 ireq = inet_rsk(req); 644 ireq->loc_addr = ip_hdr(skb)->daddr; 645 ireq->rmt_addr = ip_hdr(skb)->saddr; 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 } 672 673 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 674 675 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 676 { 677 struct dccp_hdr *dh = dccp_hdr(skb); 678 679 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 680 if (dccp_rcv_established(sk, skb, dh, skb->len)) 681 goto reset; 682 return 0; 683 } 684 685 /* 686 * Step 3: Process LISTEN state 687 * If P.type == Request or P contains a valid Init Cookie option, 688 * (* Must scan the packet's options to check for Init 689 * Cookies. Only Init Cookies are processed here, 690 * however; other options are processed in Step 8. This 691 * scan need only be performed if the endpoint uses Init 692 * Cookies *) 693 * (* Generate a new socket and switch to that socket *) 694 * Set S := new socket for this port pair 695 * S.state = RESPOND 696 * Choose S.ISS (initial seqno) or set from Init Cookies 697 * Initialize S.GAR := S.ISS 698 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 699 * Continue with S.state == RESPOND 700 * (* A Response packet will be generated in Step 11 *) 701 * Otherwise, 702 * Generate Reset(No Connection) unless P.type == Reset 703 * Drop packet and return 704 * 705 * NOTE: the check for the packet types is done in 706 * dccp_rcv_state_process 707 */ 708 if (sk->sk_state == DCCP_LISTEN) { 709 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 710 711 if (nsk == NULL) 712 goto discard; 713 714 if (nsk != sk) { 715 if (dccp_child_process(sk, nsk, skb)) 716 goto reset; 717 return 0; 718 } 719 } 720 721 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 722 goto reset; 723 return 0; 724 725 reset: 726 dccp_v4_ctl_send_reset(sk, skb); 727 discard: 728 kfree_skb(skb); 729 return 0; 730 } 731 732 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 733 734 /** 735 * dccp_invalid_packet - check for malformed packets 736 * Implements RFC 4340, 8.5: Step 1: Check header basics 737 * Packets that fail these checks are ignored and do not receive Resets. 738 */ 739 int dccp_invalid_packet(struct sk_buff *skb) 740 { 741 const struct dccp_hdr *dh; 742 unsigned int cscov; 743 744 if (skb->pkt_type != PACKET_HOST) 745 return 1; 746 747 /* If the packet is shorter than 12 bytes, drop packet and return */ 748 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 749 DCCP_WARN("pskb_may_pull failed\n"); 750 return 1; 751 } 752 753 dh = dccp_hdr(skb); 754 755 /* If P.type is not understood, drop packet and return */ 756 if (dh->dccph_type >= DCCP_PKT_INVALID) { 757 DCCP_WARN("invalid packet type\n"); 758 return 1; 759 } 760 761 /* 762 * If P.Data Offset is too small for packet type, drop packet and return 763 */ 764 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 765 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 766 return 1; 767 } 768 /* 769 * If P.Data Offset is too too large for packet, drop packet and return 770 */ 771 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 772 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 773 return 1; 774 } 775 776 /* 777 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 778 * has short sequence numbers), drop packet and return 779 */ 780 if ((dh->dccph_type < DCCP_PKT_DATA || 781 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 782 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 783 dccp_packet_name(dh->dccph_type)); 784 return 1; 785 } 786 787 /* 788 * If P.CsCov is too large for the packet size, drop packet and return. 789 * This must come _before_ checksumming (not as RFC 4340 suggests). 790 */ 791 cscov = dccp_csum_coverage(skb); 792 if (cscov > skb->len) { 793 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 794 dh->dccph_cscov, skb->len); 795 return 1; 796 } 797 798 /* If header checksum is incorrect, drop packet and return. 799 * (This step is completed in the AF-dependent functions.) */ 800 skb->csum = skb_checksum(skb, 0, cscov, 0); 801 802 return 0; 803 } 804 805 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 806 807 /* this is called when real data arrives */ 808 static int dccp_v4_rcv(struct sk_buff *skb) 809 { 810 const struct dccp_hdr *dh; 811 const struct iphdr *iph; 812 struct sock *sk; 813 int min_cov; 814 815 /* Step 1: Check header basics */ 816 817 if (dccp_invalid_packet(skb)) 818 goto discard_it; 819 820 iph = ip_hdr(skb); 821 /* Step 1: If header checksum is incorrect, drop packet and return */ 822 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 823 DCCP_WARN("dropped packet with invalid checksum\n"); 824 goto discard_it; 825 } 826 827 dh = dccp_hdr(skb); 828 829 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 830 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 831 832 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 833 dccp_packet_name(dh->dccph_type), 834 &iph->saddr, ntohs(dh->dccph_sport), 835 &iph->daddr, ntohs(dh->dccph_dport), 836 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 837 838 if (dccp_packet_without_ack(skb)) { 839 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 840 dccp_pr_debug_cat("\n"); 841 } else { 842 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 843 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 844 DCCP_SKB_CB(skb)->dccpd_ack_seq); 845 } 846 847 /* Step 2: 848 * Look up flow ID in table and get corresponding socket */ 849 sk = __inet_lookup_skb(&dccp_hashinfo, skb, 850 dh->dccph_sport, dh->dccph_dport); 851 /* 852 * Step 2: 853 * If no socket ... 854 */ 855 if (sk == NULL) { 856 dccp_pr_debug("failed to look up flow ID in table and " 857 "get corresponding socket\n"); 858 goto no_dccp_socket; 859 } 860 861 /* 862 * Step 2: 863 * ... or S.state == TIMEWAIT, 864 * Generate Reset(No Connection) unless P.type == Reset 865 * Drop packet and return 866 */ 867 if (sk->sk_state == DCCP_TIME_WAIT) { 868 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 869 inet_twsk_put(inet_twsk(sk)); 870 goto no_dccp_socket; 871 } 872 873 /* 874 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 875 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 876 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 877 */ 878 min_cov = dccp_sk(sk)->dccps_pcrlen; 879 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 880 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 881 dh->dccph_cscov, min_cov); 882 /* FIXME: "Such packets SHOULD be reported using Data Dropped 883 * options (Section 11.7) with Drop Code 0, Protocol 884 * Constraints." */ 885 goto discard_and_relse; 886 } 887 888 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 889 goto discard_and_relse; 890 nf_reset(skb); 891 892 return sk_receive_skb(sk, skb, 1); 893 894 no_dccp_socket: 895 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 896 goto discard_it; 897 /* 898 * Step 2: 899 * If no socket ... 900 * Generate Reset(No Connection) unless P.type == Reset 901 * Drop packet and return 902 */ 903 if (dh->dccph_type != DCCP_PKT_RESET) { 904 DCCP_SKB_CB(skb)->dccpd_reset_code = 905 DCCP_RESET_CODE_NO_CONNECTION; 906 dccp_v4_ctl_send_reset(sk, skb); 907 } 908 909 discard_it: 910 kfree_skb(skb); 911 return 0; 912 913 discard_and_relse: 914 sock_put(sk); 915 goto discard_it; 916 } 917 918 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 919 .queue_xmit = ip_queue_xmit, 920 .send_check = dccp_v4_send_check, 921 .rebuild_header = inet_sk_rebuild_header, 922 .conn_request = dccp_v4_conn_request, 923 .syn_recv_sock = dccp_v4_request_recv_sock, 924 .net_header_len = sizeof(struct iphdr), 925 .setsockopt = ip_setsockopt, 926 .getsockopt = ip_getsockopt, 927 .addr2sockaddr = inet_csk_addr2sockaddr, 928 .sockaddr_len = sizeof(struct sockaddr_in), 929 .bind_conflict = inet_csk_bind_conflict, 930 #ifdef CONFIG_COMPAT 931 .compat_setsockopt = compat_ip_setsockopt, 932 .compat_getsockopt = compat_ip_getsockopt, 933 #endif 934 }; 935 936 static int dccp_v4_init_sock(struct sock *sk) 937 { 938 static __u8 dccp_v4_ctl_sock_initialized; 939 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 940 941 if (err == 0) { 942 if (unlikely(!dccp_v4_ctl_sock_initialized)) 943 dccp_v4_ctl_sock_initialized = 1; 944 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 945 } 946 947 return err; 948 } 949 950 static struct timewait_sock_ops dccp_timewait_sock_ops = { 951 .twsk_obj_size = sizeof(struct inet_timewait_sock), 952 }; 953 954 static struct proto dccp_v4_prot = { 955 .name = "DCCP", 956 .owner = THIS_MODULE, 957 .close = dccp_close, 958 .connect = dccp_v4_connect, 959 .disconnect = dccp_disconnect, 960 .ioctl = dccp_ioctl, 961 .init = dccp_v4_init_sock, 962 .setsockopt = dccp_setsockopt, 963 .getsockopt = dccp_getsockopt, 964 .sendmsg = dccp_sendmsg, 965 .recvmsg = dccp_recvmsg, 966 .backlog_rcv = dccp_v4_do_rcv, 967 .hash = inet_hash, 968 .unhash = inet_unhash, 969 .accept = inet_csk_accept, 970 .get_port = inet_csk_get_port, 971 .shutdown = dccp_shutdown, 972 .destroy = dccp_destroy_sock, 973 .orphan_count = &dccp_orphan_count, 974 .max_header = MAX_DCCP_HEADER, 975 .obj_size = sizeof(struct dccp_sock), 976 .slab_flags = SLAB_DESTROY_BY_RCU, 977 .rsk_prot = &dccp_request_sock_ops, 978 .twsk_prot = &dccp_timewait_sock_ops, 979 .h.hashinfo = &dccp_hashinfo, 980 #ifdef CONFIG_COMPAT 981 .compat_setsockopt = compat_dccp_setsockopt, 982 .compat_getsockopt = compat_dccp_getsockopt, 983 #endif 984 }; 985 986 static const struct net_protocol dccp_v4_protocol = { 987 .handler = dccp_v4_rcv, 988 .err_handler = dccp_v4_err, 989 .no_policy = 1, 990 .netns_ok = 1, 991 }; 992 993 static const struct proto_ops inet_dccp_ops = { 994 .family = PF_INET, 995 .owner = THIS_MODULE, 996 .release = inet_release, 997 .bind = inet_bind, 998 .connect = inet_stream_connect, 999 .socketpair = sock_no_socketpair, 1000 .accept = inet_accept, 1001 .getname = inet_getname, 1002 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1003 .poll = dccp_poll, 1004 .ioctl = inet_ioctl, 1005 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1006 .listen = inet_dccp_listen, 1007 .shutdown = inet_shutdown, 1008 .setsockopt = sock_common_setsockopt, 1009 .getsockopt = sock_common_getsockopt, 1010 .sendmsg = inet_sendmsg, 1011 .recvmsg = sock_common_recvmsg, 1012 .mmap = sock_no_mmap, 1013 .sendpage = sock_no_sendpage, 1014 #ifdef CONFIG_COMPAT 1015 .compat_setsockopt = compat_sock_common_setsockopt, 1016 .compat_getsockopt = compat_sock_common_getsockopt, 1017 #endif 1018 }; 1019 1020 static struct inet_protosw dccp_v4_protosw = { 1021 .type = SOCK_DCCP, 1022 .protocol = IPPROTO_DCCP, 1023 .prot = &dccp_v4_prot, 1024 .ops = &inet_dccp_ops, 1025 .no_check = 0, 1026 .flags = INET_PROTOSW_ICSK, 1027 }; 1028 1029 static int __net_init dccp_v4_init_net(struct net *net) 1030 { 1031 if (dccp_hashinfo.bhash == NULL) 1032 return -ESOCKTNOSUPPORT; 1033 1034 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1035 SOCK_DCCP, IPPROTO_DCCP, net); 1036 } 1037 1038 static void __net_exit dccp_v4_exit_net(struct net *net) 1039 { 1040 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1041 } 1042 1043 static struct pernet_operations dccp_v4_ops = { 1044 .init = dccp_v4_init_net, 1045 .exit = dccp_v4_exit_net, 1046 }; 1047 1048 static int __init dccp_v4_init(void) 1049 { 1050 int err = proto_register(&dccp_v4_prot, 1); 1051 1052 if (err != 0) 1053 goto out; 1054 1055 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1056 if (err != 0) 1057 goto out_proto_unregister; 1058 1059 inet_register_protosw(&dccp_v4_protosw); 1060 1061 err = register_pernet_subsys(&dccp_v4_ops); 1062 if (err) 1063 goto out_destroy_ctl_sock; 1064 out: 1065 return err; 1066 out_destroy_ctl_sock: 1067 inet_unregister_protosw(&dccp_v4_protosw); 1068 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1069 out_proto_unregister: 1070 proto_unregister(&dccp_v4_prot); 1071 goto out; 1072 } 1073 1074 static void __exit dccp_v4_exit(void) 1075 { 1076 unregister_pernet_subsys(&dccp_v4_ops); 1077 inet_unregister_protosw(&dccp_v4_protosw); 1078 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1079 proto_unregister(&dccp_v4_prot); 1080 } 1081 1082 module_init(dccp_v4_init); 1083 module_exit(dccp_v4_exit); 1084 1085 /* 1086 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1087 * values directly, Also cover the case where the protocol is not specified, 1088 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1089 */ 1090 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1091 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1092 MODULE_LICENSE("GPL"); 1093 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1094 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1095