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 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 ip_sk_accept_pmtu(sk) && 178 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 179 dccp_sync_mss(sk, mtu); 180 181 /* 182 * From RFC 4340, sec. 14.1: 183 * 184 * DCCP-Sync packets are the best choice for upward 185 * probing, since DCCP-Sync probes do not risk application 186 * data loss. 187 */ 188 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 189 } /* else let the usual retransmit timer handle it */ 190 } 191 192 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 193 { 194 struct dst_entry *dst = __sk_dst_check(sk, 0); 195 196 if (dst) 197 dst->ops->redirect(dst, sk, skb); 198 } 199 200 /* 201 * This routine is called by the ICMP module when it gets some sort of error 202 * condition. If err < 0 then the socket should be closed and the error 203 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 204 * After adjustment header points to the first 8 bytes of the tcp header. We 205 * need to find the appropriate port. 206 * 207 * The locking strategy used here is very "optimistic". When someone else 208 * accesses the socket the ICMP is just dropped and for some paths there is no 209 * check at all. A more general error queue to queue errors for later handling 210 * is probably better. 211 */ 212 static void dccp_v4_err(struct sk_buff *skb, u32 info) 213 { 214 const struct iphdr *iph = (struct iphdr *)skb->data; 215 const u8 offset = iph->ihl << 2; 216 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 217 struct dccp_sock *dp; 218 struct inet_sock *inet; 219 const int type = icmp_hdr(skb)->type; 220 const int code = icmp_hdr(skb)->code; 221 struct sock *sk; 222 __u64 seq; 223 int err; 224 struct net *net = dev_net(skb->dev); 225 226 if (skb->len < offset + sizeof(*dh) || 227 skb->len < offset + __dccp_basic_hdr_len(dh)) { 228 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 229 return; 230 } 231 232 sk = inet_lookup(net, &dccp_hashinfo, 233 iph->daddr, dh->dccph_dport, 234 iph->saddr, dh->dccph_sport, inet_iif(skb)); 235 if (sk == NULL) { 236 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 237 return; 238 } 239 240 if (sk->sk_state == DCCP_TIME_WAIT) { 241 inet_twsk_put(inet_twsk(sk)); 242 return; 243 } 244 245 bh_lock_sock(sk); 246 /* If too many ICMPs get dropped on busy 247 * servers this needs to be solved differently. 248 */ 249 if (sock_owned_by_user(sk)) 250 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 251 252 if (sk->sk_state == DCCP_CLOSED) 253 goto out; 254 255 dp = dccp_sk(sk); 256 seq = dccp_hdr_seq(dh); 257 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 258 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 259 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 260 goto out; 261 } 262 263 switch (type) { 264 case ICMP_REDIRECT: 265 dccp_do_redirect(skb, sk); 266 goto out; 267 case ICMP_SOURCE_QUENCH: 268 /* Just silently ignore these. */ 269 goto out; 270 case ICMP_PARAMETERPROB: 271 err = EPROTO; 272 break; 273 case ICMP_DEST_UNREACH: 274 if (code > NR_ICMP_UNREACH) 275 goto out; 276 277 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 278 if (!sock_owned_by_user(sk)) 279 dccp_do_pmtu_discovery(sk, iph, info); 280 goto out; 281 } 282 283 err = icmp_err_convert[code].errno; 284 break; 285 case ICMP_TIME_EXCEEDED: 286 err = EHOSTUNREACH; 287 break; 288 default: 289 goto out; 290 } 291 292 switch (sk->sk_state) { 293 struct request_sock *req , **prev; 294 case DCCP_LISTEN: 295 if (sock_owned_by_user(sk)) 296 goto out; 297 req = inet_csk_search_req(sk, &prev, dh->dccph_dport, 298 iph->daddr, iph->saddr); 299 if (!req) 300 goto out; 301 302 /* 303 * ICMPs are not backlogged, hence we cannot get an established 304 * socket here. 305 */ 306 WARN_ON(req->sk); 307 308 if (!between48(seq, dccp_rsk(req)->dreq_iss, 309 dccp_rsk(req)->dreq_gss)) { 310 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 311 goto out; 312 } 313 /* 314 * Still in RESPOND, just remove it silently. 315 * There is no good way to pass the error to the newly 316 * created socket, and POSIX does not want network 317 * errors returned from accept(). 318 */ 319 inet_csk_reqsk_queue_drop(sk, req, prev); 320 goto out; 321 322 case DCCP_REQUESTING: 323 case DCCP_RESPOND: 324 if (!sock_owned_by_user(sk)) { 325 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 326 sk->sk_err = err; 327 328 sk->sk_error_report(sk); 329 330 dccp_done(sk); 331 } else 332 sk->sk_err_soft = err; 333 goto out; 334 } 335 336 /* If we've already connected we will keep trying 337 * until we time out, or the user gives up. 338 * 339 * rfc1122 4.2.3.9 allows to consider as hard errors 340 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 341 * but it is obsoleted by pmtu discovery). 342 * 343 * Note, that in modern internet, where routing is unreliable 344 * and in each dark corner broken firewalls sit, sending random 345 * errors ordered by their masters even this two messages finally lose 346 * their original sense (even Linux sends invalid PORT_UNREACHs) 347 * 348 * Now we are in compliance with RFCs. 349 * --ANK (980905) 350 */ 351 352 inet = inet_sk(sk); 353 if (!sock_owned_by_user(sk) && inet->recverr) { 354 sk->sk_err = err; 355 sk->sk_error_report(sk); 356 } else /* Only an error on timeout */ 357 sk->sk_err_soft = err; 358 out: 359 bh_unlock_sock(sk); 360 sock_put(sk); 361 } 362 363 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 364 __be32 src, __be32 dst) 365 { 366 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 367 } 368 369 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 370 { 371 const struct inet_sock *inet = inet_sk(sk); 372 struct dccp_hdr *dh = dccp_hdr(skb); 373 374 dccp_csum_outgoing(skb); 375 dh->dccph_checksum = dccp_v4_csum_finish(skb, 376 inet->inet_saddr, 377 inet->inet_daddr); 378 } 379 380 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 381 382 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 383 { 384 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 385 ip_hdr(skb)->saddr, 386 dccp_hdr(skb)->dccph_dport, 387 dccp_hdr(skb)->dccph_sport); 388 } 389 390 /* 391 * The three way handshake has completed - we got a valid ACK or DATAACK - 392 * now create the new socket. 393 * 394 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 395 */ 396 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 397 struct request_sock *req, 398 struct dst_entry *dst) 399 { 400 struct inet_request_sock *ireq; 401 struct inet_sock *newinet; 402 struct sock *newsk; 403 404 if (sk_acceptq_is_full(sk)) 405 goto exit_overflow; 406 407 newsk = dccp_create_openreq_child(sk, req, skb); 408 if (newsk == NULL) 409 goto exit_nonewsk; 410 411 newinet = inet_sk(newsk); 412 ireq = inet_rsk(req); 413 newinet->inet_daddr = ireq->ir_rmt_addr; 414 newinet->inet_rcv_saddr = ireq->ir_loc_addr; 415 newinet->inet_saddr = ireq->ir_loc_addr; 416 newinet->inet_opt = ireq->opt; 417 ireq->opt = NULL; 418 newinet->mc_index = inet_iif(skb); 419 newinet->mc_ttl = ip_hdr(skb)->ttl; 420 newinet->inet_id = jiffies; 421 422 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 423 goto put_and_exit; 424 425 sk_setup_caps(newsk, dst); 426 427 dccp_sync_mss(newsk, dst_mtu(dst)); 428 429 if (__inet_inherit_port(sk, newsk) < 0) 430 goto put_and_exit; 431 __inet_hash_nolisten(newsk, NULL); 432 433 return newsk; 434 435 exit_overflow: 436 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 437 exit_nonewsk: 438 dst_release(dst); 439 exit: 440 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 441 return NULL; 442 put_and_exit: 443 inet_csk_prepare_forced_close(newsk); 444 dccp_done(newsk); 445 goto exit; 446 } 447 448 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 449 450 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 451 { 452 const struct dccp_hdr *dh = dccp_hdr(skb); 453 const struct iphdr *iph = ip_hdr(skb); 454 struct sock *nsk; 455 struct request_sock **prev; 456 /* Find possible connection requests. */ 457 struct request_sock *req = inet_csk_search_req(sk, &prev, 458 dh->dccph_sport, 459 iph->saddr, iph->daddr); 460 if (req != NULL) 461 return dccp_check_req(sk, skb, req, prev); 462 463 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo, 464 iph->saddr, dh->dccph_sport, 465 iph->daddr, dh->dccph_dport, 466 inet_iif(skb)); 467 if (nsk != NULL) { 468 if (nsk->sk_state != DCCP_TIME_WAIT) { 469 bh_lock_sock(nsk); 470 return nsk; 471 } 472 inet_twsk_put(inet_twsk(nsk)); 473 return NULL; 474 } 475 476 return sk; 477 } 478 479 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 480 struct sk_buff *skb) 481 { 482 struct rtable *rt; 483 const struct iphdr *iph = ip_hdr(skb); 484 struct flowi4 fl4 = { 485 .flowi4_oif = inet_iif(skb), 486 .daddr = iph->saddr, 487 .saddr = iph->daddr, 488 .flowi4_tos = RT_CONN_FLAGS(sk), 489 .flowi4_proto = sk->sk_protocol, 490 .fl4_sport = dccp_hdr(skb)->dccph_dport, 491 .fl4_dport = dccp_hdr(skb)->dccph_sport, 492 }; 493 494 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 495 rt = ip_route_output_flow(net, &fl4, sk); 496 if (IS_ERR(rt)) { 497 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES); 498 return NULL; 499 } 500 501 return &rt->dst; 502 } 503 504 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req) 505 { 506 int err = -1; 507 struct sk_buff *skb; 508 struct dst_entry *dst; 509 struct flowi4 fl4; 510 511 dst = inet_csk_route_req(sk, &fl4, req); 512 if (dst == NULL) 513 goto out; 514 515 skb = dccp_make_response(sk, dst, req); 516 if (skb != NULL) { 517 const struct inet_request_sock *ireq = inet_rsk(req); 518 struct dccp_hdr *dh = dccp_hdr(skb); 519 520 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 521 ireq->ir_rmt_addr); 522 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 523 ireq->ir_rmt_addr, 524 ireq->opt); 525 err = net_xmit_eval(err); 526 } 527 528 out: 529 dst_release(dst); 530 return err; 531 } 532 533 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 534 { 535 int err; 536 const struct iphdr *rxiph; 537 struct sk_buff *skb; 538 struct dst_entry *dst; 539 struct net *net = dev_net(skb_dst(rxskb)->dev); 540 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 541 542 /* Never send a reset in response to a reset. */ 543 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 544 return; 545 546 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 547 return; 548 549 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 550 if (dst == NULL) 551 return; 552 553 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 554 if (skb == NULL) 555 goto out; 556 557 rxiph = ip_hdr(rxskb); 558 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 559 rxiph->daddr); 560 skb_dst_set(skb, dst_clone(dst)); 561 562 bh_lock_sock(ctl_sk); 563 err = ip_build_and_send_pkt(skb, ctl_sk, 564 rxiph->daddr, rxiph->saddr, NULL); 565 bh_unlock_sock(ctl_sk); 566 567 if (net_xmit_eval(err) == 0) { 568 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 569 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 570 } 571 out: 572 dst_release(dst); 573 } 574 575 static void dccp_v4_reqsk_destructor(struct request_sock *req) 576 { 577 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 578 kfree(inet_rsk(req)->opt); 579 } 580 581 void dccp_syn_ack_timeout(struct sock *sk, struct request_sock *req) 582 { 583 } 584 EXPORT_SYMBOL(dccp_syn_ack_timeout); 585 586 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 587 .family = PF_INET, 588 .obj_size = sizeof(struct dccp_request_sock), 589 .rtx_syn_ack = dccp_v4_send_response, 590 .send_ack = dccp_reqsk_send_ack, 591 .destructor = dccp_v4_reqsk_destructor, 592 .send_reset = dccp_v4_ctl_send_reset, 593 .syn_ack_timeout = dccp_syn_ack_timeout, 594 }; 595 596 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 597 { 598 struct inet_request_sock *ireq; 599 struct request_sock *req; 600 struct dccp_request_sock *dreq; 601 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 602 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 603 604 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 605 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 606 return 0; /* discard, don't send a reset here */ 607 608 if (dccp_bad_service_code(sk, service)) { 609 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 610 goto drop; 611 } 612 /* 613 * TW buckets are converted to open requests without 614 * limitations, they conserve resources and peer is 615 * evidently real one. 616 */ 617 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 618 if (inet_csk_reqsk_queue_is_full(sk)) 619 goto drop; 620 621 /* 622 * Accept backlog is full. If we have already queued enough 623 * of warm entries in syn queue, drop request. It is better than 624 * clogging syn queue with openreqs with exponentially increasing 625 * timeout. 626 */ 627 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 628 goto drop; 629 630 req = inet_reqsk_alloc(&dccp_request_sock_ops); 631 if (req == NULL) 632 goto drop; 633 634 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 635 goto drop_and_free; 636 637 dreq = dccp_rsk(req); 638 if (dccp_parse_options(sk, dreq, skb)) 639 goto drop_and_free; 640 641 if (security_inet_conn_request(sk, skb, req)) 642 goto drop_and_free; 643 644 ireq = inet_rsk(req); 645 ireq->ir_loc_addr = ip_hdr(skb)->daddr; 646 ireq->ir_rmt_addr = ip_hdr(skb)->saddr; 647 648 /* 649 * Step 3: Process LISTEN state 650 * 651 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 652 * 653 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 654 */ 655 dreq->dreq_isr = dcb->dccpd_seq; 656 dreq->dreq_gsr = dreq->dreq_isr; 657 dreq->dreq_iss = dccp_v4_init_sequence(skb); 658 dreq->dreq_gss = dreq->dreq_iss; 659 dreq->dreq_service = service; 660 661 if (dccp_v4_send_response(sk, req)) 662 goto drop_and_free; 663 664 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 665 return 0; 666 667 drop_and_free: 668 reqsk_free(req); 669 drop: 670 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 671 return -1; 672 } 673 674 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 675 676 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 677 { 678 struct dccp_hdr *dh = dccp_hdr(skb); 679 680 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 681 if (dccp_rcv_established(sk, skb, dh, skb->len)) 682 goto reset; 683 return 0; 684 } 685 686 /* 687 * Step 3: Process LISTEN state 688 * If P.type == Request or P contains a valid Init Cookie option, 689 * (* Must scan the packet's options to check for Init 690 * Cookies. Only Init Cookies are processed here, 691 * however; other options are processed in Step 8. This 692 * scan need only be performed if the endpoint uses Init 693 * Cookies *) 694 * (* Generate a new socket and switch to that socket *) 695 * Set S := new socket for this port pair 696 * S.state = RESPOND 697 * Choose S.ISS (initial seqno) or set from Init Cookies 698 * Initialize S.GAR := S.ISS 699 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 700 * Continue with S.state == RESPOND 701 * (* A Response packet will be generated in Step 11 *) 702 * Otherwise, 703 * Generate Reset(No Connection) unless P.type == Reset 704 * Drop packet and return 705 * 706 * NOTE: the check for the packet types is done in 707 * dccp_rcv_state_process 708 */ 709 if (sk->sk_state == DCCP_LISTEN) { 710 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 711 712 if (nsk == NULL) 713 goto discard; 714 715 if (nsk != sk) { 716 if (dccp_child_process(sk, nsk, skb)) 717 goto reset; 718 return 0; 719 } 720 } 721 722 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 723 goto reset; 724 return 0; 725 726 reset: 727 dccp_v4_ctl_send_reset(sk, skb); 728 discard: 729 kfree_skb(skb); 730 return 0; 731 } 732 733 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 734 735 /** 736 * dccp_invalid_packet - check for malformed packets 737 * Implements RFC 4340, 8.5: Step 1: Check header basics 738 * Packets that fail these checks are ignored and do not receive Resets. 739 */ 740 int dccp_invalid_packet(struct sk_buff *skb) 741 { 742 const struct dccp_hdr *dh; 743 unsigned int cscov; 744 745 if (skb->pkt_type != PACKET_HOST) 746 return 1; 747 748 /* If the packet is shorter than 12 bytes, drop packet and return */ 749 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 750 DCCP_WARN("pskb_may_pull failed\n"); 751 return 1; 752 } 753 754 dh = dccp_hdr(skb); 755 756 /* If P.type is not understood, drop packet and return */ 757 if (dh->dccph_type >= DCCP_PKT_INVALID) { 758 DCCP_WARN("invalid packet type\n"); 759 return 1; 760 } 761 762 /* 763 * If P.Data Offset is too small for packet type, drop packet and return 764 */ 765 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 766 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 767 return 1; 768 } 769 /* 770 * If P.Data Offset is too too large for packet, drop packet and return 771 */ 772 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 773 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 774 return 1; 775 } 776 777 /* 778 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 779 * has short sequence numbers), drop packet and return 780 */ 781 if ((dh->dccph_type < DCCP_PKT_DATA || 782 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 783 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 784 dccp_packet_name(dh->dccph_type)); 785 return 1; 786 } 787 788 /* 789 * If P.CsCov is too large for the packet size, drop packet and return. 790 * This must come _before_ checksumming (not as RFC 4340 suggests). 791 */ 792 cscov = dccp_csum_coverage(skb); 793 if (cscov > skb->len) { 794 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 795 dh->dccph_cscov, skb->len); 796 return 1; 797 } 798 799 /* If header checksum is incorrect, drop packet and return. 800 * (This step is completed in the AF-dependent functions.) */ 801 skb->csum = skb_checksum(skb, 0, cscov, 0); 802 803 return 0; 804 } 805 806 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 807 808 /* this is called when real data arrives */ 809 static int dccp_v4_rcv(struct sk_buff *skb) 810 { 811 const struct dccp_hdr *dh; 812 const struct iphdr *iph; 813 struct sock *sk; 814 int min_cov; 815 816 /* Step 1: Check header basics */ 817 818 if (dccp_invalid_packet(skb)) 819 goto discard_it; 820 821 iph = ip_hdr(skb); 822 /* Step 1: If header checksum is incorrect, drop packet and return */ 823 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 824 DCCP_WARN("dropped packet with invalid checksum\n"); 825 goto discard_it; 826 } 827 828 dh = dccp_hdr(skb); 829 830 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 831 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 832 833 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 834 dccp_packet_name(dh->dccph_type), 835 &iph->saddr, ntohs(dh->dccph_sport), 836 &iph->daddr, ntohs(dh->dccph_dport), 837 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 838 839 if (dccp_packet_without_ack(skb)) { 840 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 841 dccp_pr_debug_cat("\n"); 842 } else { 843 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 844 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 845 DCCP_SKB_CB(skb)->dccpd_ack_seq); 846 } 847 848 /* Step 2: 849 * Look up flow ID in table and get corresponding socket */ 850 sk = __inet_lookup_skb(&dccp_hashinfo, skb, 851 dh->dccph_sport, dh->dccph_dport); 852 /* 853 * Step 2: 854 * If no socket ... 855 */ 856 if (sk == NULL) { 857 dccp_pr_debug("failed to look up flow ID in table and " 858 "get corresponding socket\n"); 859 goto no_dccp_socket; 860 } 861 862 /* 863 * Step 2: 864 * ... or S.state == TIMEWAIT, 865 * Generate Reset(No Connection) unless P.type == Reset 866 * Drop packet and return 867 */ 868 if (sk->sk_state == DCCP_TIME_WAIT) { 869 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 870 inet_twsk_put(inet_twsk(sk)); 871 goto no_dccp_socket; 872 } 873 874 /* 875 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 876 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 877 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 878 */ 879 min_cov = dccp_sk(sk)->dccps_pcrlen; 880 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 881 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 882 dh->dccph_cscov, min_cov); 883 /* FIXME: "Such packets SHOULD be reported using Data Dropped 884 * options (Section 11.7) with Drop Code 0, Protocol 885 * Constraints." */ 886 goto discard_and_relse; 887 } 888 889 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 890 goto discard_and_relse; 891 nf_reset(skb); 892 893 return sk_receive_skb(sk, skb, 1); 894 895 no_dccp_socket: 896 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 897 goto discard_it; 898 /* 899 * Step 2: 900 * If no socket ... 901 * Generate Reset(No Connection) unless P.type == Reset 902 * Drop packet and return 903 */ 904 if (dh->dccph_type != DCCP_PKT_RESET) { 905 DCCP_SKB_CB(skb)->dccpd_reset_code = 906 DCCP_RESET_CODE_NO_CONNECTION; 907 dccp_v4_ctl_send_reset(sk, skb); 908 } 909 910 discard_it: 911 kfree_skb(skb); 912 return 0; 913 914 discard_and_relse: 915 sock_put(sk); 916 goto discard_it; 917 } 918 919 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 920 .queue_xmit = ip_queue_xmit, 921 .send_check = dccp_v4_send_check, 922 .rebuild_header = inet_sk_rebuild_header, 923 .conn_request = dccp_v4_conn_request, 924 .syn_recv_sock = dccp_v4_request_recv_sock, 925 .net_header_len = sizeof(struct iphdr), 926 .setsockopt = ip_setsockopt, 927 .getsockopt = ip_getsockopt, 928 .addr2sockaddr = inet_csk_addr2sockaddr, 929 .sockaddr_len = sizeof(struct sockaddr_in), 930 .bind_conflict = inet_csk_bind_conflict, 931 #ifdef CONFIG_COMPAT 932 .compat_setsockopt = compat_ip_setsockopt, 933 .compat_getsockopt = compat_ip_getsockopt, 934 #endif 935 }; 936 937 static int dccp_v4_init_sock(struct sock *sk) 938 { 939 static __u8 dccp_v4_ctl_sock_initialized; 940 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 941 942 if (err == 0) { 943 if (unlikely(!dccp_v4_ctl_sock_initialized)) 944 dccp_v4_ctl_sock_initialized = 1; 945 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 946 } 947 948 return err; 949 } 950 951 static struct timewait_sock_ops dccp_timewait_sock_ops = { 952 .twsk_obj_size = sizeof(struct inet_timewait_sock), 953 }; 954 955 static struct proto dccp_v4_prot = { 956 .name = "DCCP", 957 .owner = THIS_MODULE, 958 .close = dccp_close, 959 .connect = dccp_v4_connect, 960 .disconnect = dccp_disconnect, 961 .ioctl = dccp_ioctl, 962 .init = dccp_v4_init_sock, 963 .setsockopt = dccp_setsockopt, 964 .getsockopt = dccp_getsockopt, 965 .sendmsg = dccp_sendmsg, 966 .recvmsg = dccp_recvmsg, 967 .backlog_rcv = dccp_v4_do_rcv, 968 .hash = inet_hash, 969 .unhash = inet_unhash, 970 .accept = inet_csk_accept, 971 .get_port = inet_csk_get_port, 972 .shutdown = dccp_shutdown, 973 .destroy = dccp_destroy_sock, 974 .orphan_count = &dccp_orphan_count, 975 .max_header = MAX_DCCP_HEADER, 976 .obj_size = sizeof(struct dccp_sock), 977 .slab_flags = SLAB_DESTROY_BY_RCU, 978 .rsk_prot = &dccp_request_sock_ops, 979 .twsk_prot = &dccp_timewait_sock_ops, 980 .h.hashinfo = &dccp_hashinfo, 981 #ifdef CONFIG_COMPAT 982 .compat_setsockopt = compat_dccp_setsockopt, 983 .compat_getsockopt = compat_dccp_getsockopt, 984 #endif 985 }; 986 987 static const struct net_protocol dccp_v4_protocol = { 988 .handler = dccp_v4_rcv, 989 .err_handler = dccp_v4_err, 990 .no_policy = 1, 991 .netns_ok = 1, 992 .icmp_strict_tag_validation = 1, 993 }; 994 995 static const struct proto_ops inet_dccp_ops = { 996 .family = PF_INET, 997 .owner = THIS_MODULE, 998 .release = inet_release, 999 .bind = inet_bind, 1000 .connect = inet_stream_connect, 1001 .socketpair = sock_no_socketpair, 1002 .accept = inet_accept, 1003 .getname = inet_getname, 1004 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1005 .poll = dccp_poll, 1006 .ioctl = inet_ioctl, 1007 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1008 .listen = inet_dccp_listen, 1009 .shutdown = inet_shutdown, 1010 .setsockopt = sock_common_setsockopt, 1011 .getsockopt = sock_common_getsockopt, 1012 .sendmsg = inet_sendmsg, 1013 .recvmsg = sock_common_recvmsg, 1014 .mmap = sock_no_mmap, 1015 .sendpage = sock_no_sendpage, 1016 #ifdef CONFIG_COMPAT 1017 .compat_setsockopt = compat_sock_common_setsockopt, 1018 .compat_getsockopt = compat_sock_common_getsockopt, 1019 #endif 1020 }; 1021 1022 static struct inet_protosw dccp_v4_protosw = { 1023 .type = SOCK_DCCP, 1024 .protocol = IPPROTO_DCCP, 1025 .prot = &dccp_v4_prot, 1026 .ops = &inet_dccp_ops, 1027 .no_check = 0, 1028 .flags = INET_PROTOSW_ICSK, 1029 }; 1030 1031 static int __net_init dccp_v4_init_net(struct net *net) 1032 { 1033 if (dccp_hashinfo.bhash == NULL) 1034 return -ESOCKTNOSUPPORT; 1035 1036 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1037 SOCK_DCCP, IPPROTO_DCCP, net); 1038 } 1039 1040 static void __net_exit dccp_v4_exit_net(struct net *net) 1041 { 1042 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1043 } 1044 1045 static struct pernet_operations dccp_v4_ops = { 1046 .init = dccp_v4_init_net, 1047 .exit = dccp_v4_exit_net, 1048 }; 1049 1050 static int __init dccp_v4_init(void) 1051 { 1052 int err = proto_register(&dccp_v4_prot, 1); 1053 1054 if (err != 0) 1055 goto out; 1056 1057 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1058 if (err != 0) 1059 goto out_proto_unregister; 1060 1061 inet_register_protosw(&dccp_v4_protosw); 1062 1063 err = register_pernet_subsys(&dccp_v4_ops); 1064 if (err) 1065 goto out_destroy_ctl_sock; 1066 out: 1067 return err; 1068 out_destroy_ctl_sock: 1069 inet_unregister_protosw(&dccp_v4_protosw); 1070 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1071 out_proto_unregister: 1072 proto_unregister(&dccp_v4_prot); 1073 goto out; 1074 } 1075 1076 static void __exit dccp_v4_exit(void) 1077 { 1078 unregister_pernet_subsys(&dccp_v4_ops); 1079 inet_unregister_protosw(&dccp_v4_protosw); 1080 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1081 proto_unregister(&dccp_v4_prot); 1082 } 1083 1084 module_init(dccp_v4_init); 1085 module_exit(dccp_v4_exit); 1086 1087 /* 1088 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1089 * values directly, Also cover the case where the protocol is not specified, 1090 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1091 */ 1092 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1093 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1094 MODULE_LICENSE("GPL"); 1095 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1096 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1097