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