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 lockdep_sock_is_held(sk)); 66 if (inet_opt != NULL && inet_opt->opt.srr) { 67 if (daddr == 0) 68 return -EINVAL; 69 nexthop = inet_opt->opt.faddr; 70 } 71 72 orig_sport = inet->inet_sport; 73 orig_dport = usin->sin_port; 74 fl4 = &inet->cork.fl.u.ip4; 75 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 76 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 77 IPPROTO_DCCP, 78 orig_sport, orig_dport, sk); 79 if (IS_ERR(rt)) 80 return PTR_ERR(rt); 81 82 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 83 ip_rt_put(rt); 84 return -ENETUNREACH; 85 } 86 87 if (inet_opt == NULL || !inet_opt->opt.srr) 88 daddr = fl4->daddr; 89 90 if (inet->inet_saddr == 0) 91 inet->inet_saddr = fl4->saddr; 92 sk_rcv_saddr_set(sk, inet->inet_saddr); 93 inet->inet_dport = usin->sin_port; 94 sk_daddr_set(sk, daddr); 95 96 inet_csk(sk)->icsk_ext_hdr_len = 0; 97 if (inet_opt) 98 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 99 /* 100 * Socket identity is still unknown (sport may be zero). 101 * However we set state to DCCP_REQUESTING and not releasing socket 102 * lock select source port, enter ourselves into the hash tables and 103 * complete initialization after this. 104 */ 105 dccp_set_state(sk, DCCP_REQUESTING); 106 err = inet_hash_connect(&dccp_death_row, sk); 107 if (err != 0) 108 goto failure; 109 110 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 111 inet->inet_sport, inet->inet_dport, sk); 112 if (IS_ERR(rt)) { 113 err = PTR_ERR(rt); 114 rt = NULL; 115 goto failure; 116 } 117 /* OK, now commit destination to socket. */ 118 sk_setup_caps(sk, &rt->dst); 119 120 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 121 inet->inet_daddr, 122 inet->inet_sport, 123 inet->inet_dport); 124 inet->inet_id = dp->dccps_iss ^ jiffies; 125 126 err = dccp_connect(sk); 127 rt = NULL; 128 if (err != 0) 129 goto failure; 130 out: 131 return err; 132 failure: 133 /* 134 * This unhashes the socket and releases the local port, if necessary. 135 */ 136 dccp_set_state(sk, DCCP_CLOSED); 137 ip_rt_put(rt); 138 sk->sk_route_caps = 0; 139 inet->inet_dport = 0; 140 goto out; 141 } 142 EXPORT_SYMBOL_GPL(dccp_v4_connect); 143 144 /* 145 * This routine does path mtu discovery as defined in RFC1191. 146 */ 147 static inline void dccp_do_pmtu_discovery(struct sock *sk, 148 const struct iphdr *iph, 149 u32 mtu) 150 { 151 struct dst_entry *dst; 152 const struct inet_sock *inet = inet_sk(sk); 153 const struct dccp_sock *dp = dccp_sk(sk); 154 155 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 156 * send out by Linux are always < 576bytes so they should go through 157 * unfragmented). 158 */ 159 if (sk->sk_state == DCCP_LISTEN) 160 return; 161 162 dst = inet_csk_update_pmtu(sk, mtu); 163 if (!dst) 164 return; 165 166 /* Something is about to be wrong... Remember soft error 167 * for the case, if this connection will not able to recover. 168 */ 169 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 170 sk->sk_err_soft = EMSGSIZE; 171 172 mtu = dst_mtu(dst); 173 174 if (inet->pmtudisc != IP_PMTUDISC_DONT && 175 ip_sk_accept_pmtu(sk) && 176 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 177 dccp_sync_mss(sk, mtu); 178 179 /* 180 * From RFC 4340, sec. 14.1: 181 * 182 * DCCP-Sync packets are the best choice for upward 183 * probing, since DCCP-Sync probes do not risk application 184 * data loss. 185 */ 186 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 187 } /* else let the usual retransmit timer handle it */ 188 } 189 190 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 191 { 192 struct dst_entry *dst = __sk_dst_check(sk, 0); 193 194 if (dst) 195 dst->ops->redirect(dst, sk, skb); 196 } 197 198 void dccp_req_err(struct sock *sk, u64 seq) 199 { 200 struct request_sock *req = inet_reqsk(sk); 201 struct net *net = sock_net(sk); 202 203 /* 204 * ICMPs are not backlogged, hence we cannot get an established 205 * socket here. 206 */ 207 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 208 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 209 } else { 210 /* 211 * Still in RESPOND, just remove it silently. 212 * There is no good way to pass the error to the newly 213 * created socket, and POSIX does not want network 214 * errors returned from accept(). 215 */ 216 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 217 } 218 reqsk_put(req); 219 } 220 EXPORT_SYMBOL(dccp_req_err); 221 222 /* 223 * This routine is called by the ICMP module when it gets some sort of error 224 * condition. If err < 0 then the socket should be closed and the error 225 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 226 * After adjustment header points to the first 8 bytes of the tcp header. We 227 * need to find the appropriate port. 228 * 229 * The locking strategy used here is very "optimistic". When someone else 230 * accesses the socket the ICMP is just dropped and for some paths there is no 231 * check at all. A more general error queue to queue errors for later handling 232 * is probably better. 233 */ 234 static void dccp_v4_err(struct sk_buff *skb, u32 info) 235 { 236 const struct iphdr *iph = (struct iphdr *)skb->data; 237 const u8 offset = iph->ihl << 2; 238 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); 239 struct dccp_sock *dp; 240 struct inet_sock *inet; 241 const int type = icmp_hdr(skb)->type; 242 const int code = icmp_hdr(skb)->code; 243 struct sock *sk; 244 __u64 seq; 245 int err; 246 struct net *net = dev_net(skb->dev); 247 248 if (skb->len < offset + sizeof(*dh) || 249 skb->len < offset + __dccp_basic_hdr_len(dh)) { 250 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 251 return; 252 } 253 254 sk = __inet_lookup_established(net, &dccp_hashinfo, 255 iph->daddr, dh->dccph_dport, 256 iph->saddr, ntohs(dh->dccph_sport), 257 inet_iif(skb)); 258 if (!sk) { 259 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 260 return; 261 } 262 263 if (sk->sk_state == DCCP_TIME_WAIT) { 264 inet_twsk_put(inet_twsk(sk)); 265 return; 266 } 267 seq = dccp_hdr_seq(dh); 268 if (sk->sk_state == DCCP_NEW_SYN_RECV) 269 return dccp_req_err(sk, seq); 270 271 bh_lock_sock(sk); 272 /* If too many ICMPs get dropped on busy 273 * servers this needs to be solved differently. 274 */ 275 if (sock_owned_by_user(sk)) 276 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 277 278 if (sk->sk_state == DCCP_CLOSED) 279 goto out; 280 281 dp = dccp_sk(sk); 282 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 283 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 284 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 285 goto out; 286 } 287 288 switch (type) { 289 case ICMP_REDIRECT: 290 dccp_do_redirect(skb, sk); 291 goto out; 292 case ICMP_SOURCE_QUENCH: 293 /* Just silently ignore these. */ 294 goto out; 295 case ICMP_PARAMETERPROB: 296 err = EPROTO; 297 break; 298 case ICMP_DEST_UNREACH: 299 if (code > NR_ICMP_UNREACH) 300 goto out; 301 302 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 303 if (!sock_owned_by_user(sk)) 304 dccp_do_pmtu_discovery(sk, iph, info); 305 goto out; 306 } 307 308 err = icmp_err_convert[code].errno; 309 break; 310 case ICMP_TIME_EXCEEDED: 311 err = EHOSTUNREACH; 312 break; 313 default: 314 goto out; 315 } 316 317 switch (sk->sk_state) { 318 case DCCP_REQUESTING: 319 case DCCP_RESPOND: 320 if (!sock_owned_by_user(sk)) { 321 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 322 sk->sk_err = err; 323 324 sk->sk_error_report(sk); 325 326 dccp_done(sk); 327 } else 328 sk->sk_err_soft = err; 329 goto out; 330 } 331 332 /* If we've already connected we will keep trying 333 * until we time out, or the user gives up. 334 * 335 * rfc1122 4.2.3.9 allows to consider as hard errors 336 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 337 * but it is obsoleted by pmtu discovery). 338 * 339 * Note, that in modern internet, where routing is unreliable 340 * and in each dark corner broken firewalls sit, sending random 341 * errors ordered by their masters even this two messages finally lose 342 * their original sense (even Linux sends invalid PORT_UNREACHs) 343 * 344 * Now we are in compliance with RFCs. 345 * --ANK (980905) 346 */ 347 348 inet = inet_sk(sk); 349 if (!sock_owned_by_user(sk) && inet->recverr) { 350 sk->sk_err = err; 351 sk->sk_error_report(sk); 352 } else /* Only an error on timeout */ 353 sk->sk_err_soft = err; 354 out: 355 bh_unlock_sock(sk); 356 sock_put(sk); 357 } 358 359 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 360 __be32 src, __be32 dst) 361 { 362 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 363 } 364 365 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 366 { 367 const struct inet_sock *inet = inet_sk(sk); 368 struct dccp_hdr *dh = dccp_hdr(skb); 369 370 dccp_csum_outgoing(skb); 371 dh->dccph_checksum = dccp_v4_csum_finish(skb, 372 inet->inet_saddr, 373 inet->inet_daddr); 374 } 375 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 376 377 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 378 { 379 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 380 ip_hdr(skb)->saddr, 381 dccp_hdr(skb)->dccph_dport, 382 dccp_hdr(skb)->dccph_sport); 383 } 384 385 /* 386 * The three way handshake has completed - we got a valid ACK or DATAACK - 387 * now create the new socket. 388 * 389 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 390 */ 391 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 392 struct sk_buff *skb, 393 struct request_sock *req, 394 struct dst_entry *dst, 395 struct request_sock *req_unhash, 396 bool *own_req) 397 { 398 struct inet_request_sock *ireq; 399 struct inet_sock *newinet; 400 struct sock *newsk; 401 402 if (sk_acceptq_is_full(sk)) 403 goto exit_overflow; 404 405 newsk = dccp_create_openreq_child(sk, req, skb); 406 if (newsk == NULL) 407 goto exit_nonewsk; 408 409 newinet = inet_sk(newsk); 410 ireq = inet_rsk(req); 411 sk_daddr_set(newsk, ireq->ir_rmt_addr); 412 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 413 newinet->inet_saddr = ireq->ir_loc_addr; 414 newinet->inet_opt = ireq->opt; 415 ireq->opt = NULL; 416 newinet->mc_index = inet_iif(skb); 417 newinet->mc_ttl = ip_hdr(skb)->ttl; 418 newinet->inet_id = jiffies; 419 420 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 421 goto put_and_exit; 422 423 sk_setup_caps(newsk, dst); 424 425 dccp_sync_mss(newsk, dst_mtu(dst)); 426 427 if (__inet_inherit_port(sk, newsk) < 0) 428 goto put_and_exit; 429 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 430 431 return newsk; 432 433 exit_overflow: 434 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 435 exit_nonewsk: 436 dst_release(dst); 437 exit: 438 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 439 return NULL; 440 put_and_exit: 441 inet_csk_prepare_forced_close(newsk); 442 dccp_done(newsk); 443 goto exit; 444 } 445 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 446 447 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 448 struct sk_buff *skb) 449 { 450 struct rtable *rt; 451 const struct iphdr *iph = ip_hdr(skb); 452 struct flowi4 fl4 = { 453 .flowi4_oif = inet_iif(skb), 454 .daddr = iph->saddr, 455 .saddr = iph->daddr, 456 .flowi4_tos = RT_CONN_FLAGS(sk), 457 .flowi4_proto = sk->sk_protocol, 458 .fl4_sport = dccp_hdr(skb)->dccph_dport, 459 .fl4_dport = dccp_hdr(skb)->dccph_sport, 460 }; 461 462 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 463 rt = ip_route_output_flow(net, &fl4, sk); 464 if (IS_ERR(rt)) { 465 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 466 return NULL; 467 } 468 469 return &rt->dst; 470 } 471 472 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 473 { 474 int err = -1; 475 struct sk_buff *skb; 476 struct dst_entry *dst; 477 struct flowi4 fl4; 478 479 dst = inet_csk_route_req(sk, &fl4, req); 480 if (dst == NULL) 481 goto out; 482 483 skb = dccp_make_response(sk, dst, req); 484 if (skb != NULL) { 485 const struct inet_request_sock *ireq = inet_rsk(req); 486 struct dccp_hdr *dh = dccp_hdr(skb); 487 488 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 489 ireq->ir_rmt_addr); 490 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 491 ireq->ir_rmt_addr, 492 ireq->opt); 493 err = net_xmit_eval(err); 494 } 495 496 out: 497 dst_release(dst); 498 return err; 499 } 500 501 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 502 { 503 int err; 504 const struct iphdr *rxiph; 505 struct sk_buff *skb; 506 struct dst_entry *dst; 507 struct net *net = dev_net(skb_dst(rxskb)->dev); 508 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 509 510 /* Never send a reset in response to a reset. */ 511 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 512 return; 513 514 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 515 return; 516 517 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 518 if (dst == NULL) 519 return; 520 521 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 522 if (skb == NULL) 523 goto out; 524 525 rxiph = ip_hdr(rxskb); 526 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 527 rxiph->daddr); 528 skb_dst_set(skb, dst_clone(dst)); 529 530 local_bh_disable(); 531 bh_lock_sock(ctl_sk); 532 err = ip_build_and_send_pkt(skb, ctl_sk, 533 rxiph->daddr, rxiph->saddr, NULL); 534 bh_unlock_sock(ctl_sk); 535 536 if (net_xmit_eval(err) == 0) { 537 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 538 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 539 } 540 local_bh_enable(); 541 out: 542 dst_release(dst); 543 } 544 545 static void dccp_v4_reqsk_destructor(struct request_sock *req) 546 { 547 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 548 kfree(inet_rsk(req)->opt); 549 } 550 551 void dccp_syn_ack_timeout(const struct request_sock *req) 552 { 553 } 554 EXPORT_SYMBOL(dccp_syn_ack_timeout); 555 556 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 557 .family = PF_INET, 558 .obj_size = sizeof(struct dccp_request_sock), 559 .rtx_syn_ack = dccp_v4_send_response, 560 .send_ack = dccp_reqsk_send_ack, 561 .destructor = dccp_v4_reqsk_destructor, 562 .send_reset = dccp_v4_ctl_send_reset, 563 .syn_ack_timeout = dccp_syn_ack_timeout, 564 }; 565 566 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 567 { 568 struct inet_request_sock *ireq; 569 struct request_sock *req; 570 struct dccp_request_sock *dreq; 571 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 572 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 573 574 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 575 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 576 return 0; /* discard, don't send a reset here */ 577 578 if (dccp_bad_service_code(sk, service)) { 579 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 580 goto drop; 581 } 582 /* 583 * TW buckets are converted to open requests without 584 * limitations, they conserve resources and peer is 585 * evidently real one. 586 */ 587 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 588 if (inet_csk_reqsk_queue_is_full(sk)) 589 goto drop; 590 591 /* 592 * Accept backlog is full. If we have already queued enough 593 * of warm entries in syn queue, drop request. It is better than 594 * clogging syn queue with openreqs with exponentially increasing 595 * timeout. 596 */ 597 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 598 goto drop; 599 600 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 601 if (req == NULL) 602 goto drop; 603 604 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 605 goto drop_and_free; 606 607 dreq = dccp_rsk(req); 608 if (dccp_parse_options(sk, dreq, skb)) 609 goto drop_and_free; 610 611 if (security_inet_conn_request(sk, skb, req)) 612 goto drop_and_free; 613 614 ireq = inet_rsk(req); 615 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 616 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 617 ireq->ireq_family = AF_INET; 618 ireq->ir_iif = sk->sk_bound_dev_if; 619 620 /* 621 * Step 3: Process LISTEN state 622 * 623 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 624 * 625 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 626 */ 627 dreq->dreq_isr = dcb->dccpd_seq; 628 dreq->dreq_gsr = dreq->dreq_isr; 629 dreq->dreq_iss = dccp_v4_init_sequence(skb); 630 dreq->dreq_gss = dreq->dreq_iss; 631 dreq->dreq_service = service; 632 633 if (dccp_v4_send_response(sk, req)) 634 goto drop_and_free; 635 636 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 637 return 0; 638 639 drop_and_free: 640 reqsk_free(req); 641 drop: 642 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 643 return -1; 644 } 645 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 646 647 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 648 { 649 struct dccp_hdr *dh = dccp_hdr(skb); 650 651 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 652 if (dccp_rcv_established(sk, skb, dh, skb->len)) 653 goto reset; 654 return 0; 655 } 656 657 /* 658 * Step 3: Process LISTEN state 659 * If P.type == Request or P contains a valid Init Cookie option, 660 * (* Must scan the packet's options to check for Init 661 * Cookies. Only Init Cookies are processed here, 662 * however; other options are processed in Step 8. This 663 * scan need only be performed if the endpoint uses Init 664 * Cookies *) 665 * (* Generate a new socket and switch to that socket *) 666 * Set S := new socket for this port pair 667 * S.state = RESPOND 668 * Choose S.ISS (initial seqno) or set from Init Cookies 669 * Initialize S.GAR := S.ISS 670 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 671 * Continue with S.state == RESPOND 672 * (* A Response packet will be generated in Step 11 *) 673 * Otherwise, 674 * Generate Reset(No Connection) unless P.type == Reset 675 * Drop packet and return 676 * 677 * NOTE: the check for the packet types is done in 678 * dccp_rcv_state_process 679 */ 680 681 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 682 goto reset; 683 return 0; 684 685 reset: 686 dccp_v4_ctl_send_reset(sk, skb); 687 kfree_skb(skb); 688 return 0; 689 } 690 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 691 692 /** 693 * dccp_invalid_packet - check for malformed packets 694 * Implements RFC 4340, 8.5: Step 1: Check header basics 695 * Packets that fail these checks are ignored and do not receive Resets. 696 */ 697 int dccp_invalid_packet(struct sk_buff *skb) 698 { 699 const struct dccp_hdr *dh; 700 unsigned int cscov; 701 702 if (skb->pkt_type != PACKET_HOST) 703 return 1; 704 705 /* If the packet is shorter than 12 bytes, drop packet and return */ 706 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 707 DCCP_WARN("pskb_may_pull failed\n"); 708 return 1; 709 } 710 711 dh = dccp_hdr(skb); 712 713 /* If P.type is not understood, drop packet and return */ 714 if (dh->dccph_type >= DCCP_PKT_INVALID) { 715 DCCP_WARN("invalid packet type\n"); 716 return 1; 717 } 718 719 /* 720 * If P.Data Offset is too small for packet type, drop packet and return 721 */ 722 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 723 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); 724 return 1; 725 } 726 /* 727 * If P.Data Offset is too too large for packet, drop packet and return 728 */ 729 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 730 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); 731 return 1; 732 } 733 734 /* 735 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 736 * has short sequence numbers), drop packet and return 737 */ 738 if ((dh->dccph_type < DCCP_PKT_DATA || 739 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 740 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 741 dccp_packet_name(dh->dccph_type)); 742 return 1; 743 } 744 745 /* 746 * If P.CsCov is too large for the packet size, drop packet and return. 747 * This must come _before_ checksumming (not as RFC 4340 suggests). 748 */ 749 cscov = dccp_csum_coverage(skb); 750 if (cscov > skb->len) { 751 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 752 dh->dccph_cscov, skb->len); 753 return 1; 754 } 755 756 /* If header checksum is incorrect, drop packet and return. 757 * (This step is completed in the AF-dependent functions.) */ 758 skb->csum = skb_checksum(skb, 0, cscov, 0); 759 760 return 0; 761 } 762 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 763 764 /* this is called when real data arrives */ 765 static int dccp_v4_rcv(struct sk_buff *skb) 766 { 767 const struct dccp_hdr *dh; 768 const struct iphdr *iph; 769 bool refcounted; 770 struct sock *sk; 771 int min_cov; 772 773 /* Step 1: Check header basics */ 774 775 if (dccp_invalid_packet(skb)) 776 goto discard_it; 777 778 iph = ip_hdr(skb); 779 /* Step 1: If header checksum is incorrect, drop packet and return */ 780 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 781 DCCP_WARN("dropped packet with invalid checksum\n"); 782 goto discard_it; 783 } 784 785 dh = dccp_hdr(skb); 786 787 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 788 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 789 790 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 791 dccp_packet_name(dh->dccph_type), 792 &iph->saddr, ntohs(dh->dccph_sport), 793 &iph->daddr, ntohs(dh->dccph_dport), 794 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 795 796 if (dccp_packet_without_ack(skb)) { 797 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 798 dccp_pr_debug_cat("\n"); 799 } else { 800 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 801 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 802 DCCP_SKB_CB(skb)->dccpd_ack_seq); 803 } 804 805 lookup: 806 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 807 dh->dccph_sport, dh->dccph_dport, &refcounted); 808 if (!sk) { 809 dccp_pr_debug("failed to look up flow ID in table and " 810 "get corresponding socket\n"); 811 goto no_dccp_socket; 812 } 813 814 /* 815 * Step 2: 816 * ... or S.state == TIMEWAIT, 817 * Generate Reset(No Connection) unless P.type == Reset 818 * Drop packet and return 819 */ 820 if (sk->sk_state == DCCP_TIME_WAIT) { 821 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 822 inet_twsk_put(inet_twsk(sk)); 823 goto no_dccp_socket; 824 } 825 826 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 827 struct request_sock *req = inet_reqsk(sk); 828 struct sock *nsk; 829 830 sk = req->rsk_listener; 831 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 832 inet_csk_reqsk_queue_drop_and_put(sk, req); 833 goto lookup; 834 } 835 sock_hold(sk); 836 refcounted = true; 837 nsk = dccp_check_req(sk, skb, req); 838 if (!nsk) { 839 reqsk_put(req); 840 goto discard_and_relse; 841 } 842 if (nsk == sk) { 843 reqsk_put(req); 844 } else if (dccp_child_process(sk, nsk, skb)) { 845 dccp_v4_ctl_send_reset(sk, skb); 846 goto discard_and_relse; 847 } else { 848 sock_put(sk); 849 return 0; 850 } 851 } 852 /* 853 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 854 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 855 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 856 */ 857 min_cov = dccp_sk(sk)->dccps_pcrlen; 858 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 859 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 860 dh->dccph_cscov, min_cov); 861 /* FIXME: "Such packets SHOULD be reported using Data Dropped 862 * options (Section 11.7) with Drop Code 0, Protocol 863 * Constraints." */ 864 goto discard_and_relse; 865 } 866 867 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 868 goto discard_and_relse; 869 nf_reset(skb); 870 871 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4); 872 873 no_dccp_socket: 874 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 875 goto discard_it; 876 /* 877 * Step 2: 878 * If no socket ... 879 * Generate Reset(No Connection) unless P.type == Reset 880 * Drop packet and return 881 */ 882 if (dh->dccph_type != DCCP_PKT_RESET) { 883 DCCP_SKB_CB(skb)->dccpd_reset_code = 884 DCCP_RESET_CODE_NO_CONNECTION; 885 dccp_v4_ctl_send_reset(sk, skb); 886 } 887 888 discard_it: 889 kfree_skb(skb); 890 return 0; 891 892 discard_and_relse: 893 if (refcounted) 894 sock_put(sk); 895 goto discard_it; 896 } 897 898 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 899 .queue_xmit = ip_queue_xmit, 900 .send_check = dccp_v4_send_check, 901 .rebuild_header = inet_sk_rebuild_header, 902 .conn_request = dccp_v4_conn_request, 903 .syn_recv_sock = dccp_v4_request_recv_sock, 904 .net_header_len = sizeof(struct iphdr), 905 .setsockopt = ip_setsockopt, 906 .getsockopt = ip_getsockopt, 907 .addr2sockaddr = inet_csk_addr2sockaddr, 908 .sockaddr_len = sizeof(struct sockaddr_in), 909 .bind_conflict = inet_csk_bind_conflict, 910 #ifdef CONFIG_COMPAT 911 .compat_setsockopt = compat_ip_setsockopt, 912 .compat_getsockopt = compat_ip_getsockopt, 913 #endif 914 }; 915 916 static int dccp_v4_init_sock(struct sock *sk) 917 { 918 static __u8 dccp_v4_ctl_sock_initialized; 919 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 920 921 if (err == 0) { 922 if (unlikely(!dccp_v4_ctl_sock_initialized)) 923 dccp_v4_ctl_sock_initialized = 1; 924 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 925 } 926 927 return err; 928 } 929 930 static struct timewait_sock_ops dccp_timewait_sock_ops = { 931 .twsk_obj_size = sizeof(struct inet_timewait_sock), 932 }; 933 934 static struct proto dccp_v4_prot = { 935 .name = "DCCP", 936 .owner = THIS_MODULE, 937 .close = dccp_close, 938 .connect = dccp_v4_connect, 939 .disconnect = dccp_disconnect, 940 .ioctl = dccp_ioctl, 941 .init = dccp_v4_init_sock, 942 .setsockopt = dccp_setsockopt, 943 .getsockopt = dccp_getsockopt, 944 .sendmsg = dccp_sendmsg, 945 .recvmsg = dccp_recvmsg, 946 .backlog_rcv = dccp_v4_do_rcv, 947 .hash = inet_hash, 948 .unhash = inet_unhash, 949 .accept = inet_csk_accept, 950 .get_port = inet_csk_get_port, 951 .shutdown = dccp_shutdown, 952 .destroy = dccp_destroy_sock, 953 .orphan_count = &dccp_orphan_count, 954 .max_header = MAX_DCCP_HEADER, 955 .obj_size = sizeof(struct dccp_sock), 956 .slab_flags = SLAB_DESTROY_BY_RCU, 957 .rsk_prot = &dccp_request_sock_ops, 958 .twsk_prot = &dccp_timewait_sock_ops, 959 .h.hashinfo = &dccp_hashinfo, 960 #ifdef CONFIG_COMPAT 961 .compat_setsockopt = compat_dccp_setsockopt, 962 .compat_getsockopt = compat_dccp_getsockopt, 963 #endif 964 }; 965 966 static const struct net_protocol dccp_v4_protocol = { 967 .handler = dccp_v4_rcv, 968 .err_handler = dccp_v4_err, 969 .no_policy = 1, 970 .netns_ok = 1, 971 .icmp_strict_tag_validation = 1, 972 }; 973 974 static const struct proto_ops inet_dccp_ops = { 975 .family = PF_INET, 976 .owner = THIS_MODULE, 977 .release = inet_release, 978 .bind = inet_bind, 979 .connect = inet_stream_connect, 980 .socketpair = sock_no_socketpair, 981 .accept = inet_accept, 982 .getname = inet_getname, 983 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 984 .poll = dccp_poll, 985 .ioctl = inet_ioctl, 986 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 987 .listen = inet_dccp_listen, 988 .shutdown = inet_shutdown, 989 .setsockopt = sock_common_setsockopt, 990 .getsockopt = sock_common_getsockopt, 991 .sendmsg = inet_sendmsg, 992 .recvmsg = sock_common_recvmsg, 993 .mmap = sock_no_mmap, 994 .sendpage = sock_no_sendpage, 995 #ifdef CONFIG_COMPAT 996 .compat_setsockopt = compat_sock_common_setsockopt, 997 .compat_getsockopt = compat_sock_common_getsockopt, 998 #endif 999 }; 1000 1001 static struct inet_protosw dccp_v4_protosw = { 1002 .type = SOCK_DCCP, 1003 .protocol = IPPROTO_DCCP, 1004 .prot = &dccp_v4_prot, 1005 .ops = &inet_dccp_ops, 1006 .flags = INET_PROTOSW_ICSK, 1007 }; 1008 1009 static int __net_init dccp_v4_init_net(struct net *net) 1010 { 1011 if (dccp_hashinfo.bhash == NULL) 1012 return -ESOCKTNOSUPPORT; 1013 1014 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1015 SOCK_DCCP, IPPROTO_DCCP, net); 1016 } 1017 1018 static void __net_exit dccp_v4_exit_net(struct net *net) 1019 { 1020 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1021 } 1022 1023 static struct pernet_operations dccp_v4_ops = { 1024 .init = dccp_v4_init_net, 1025 .exit = dccp_v4_exit_net, 1026 }; 1027 1028 static int __init dccp_v4_init(void) 1029 { 1030 int err = proto_register(&dccp_v4_prot, 1); 1031 1032 if (err != 0) 1033 goto out; 1034 1035 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1036 if (err != 0) 1037 goto out_proto_unregister; 1038 1039 inet_register_protosw(&dccp_v4_protosw); 1040 1041 err = register_pernet_subsys(&dccp_v4_ops); 1042 if (err) 1043 goto out_destroy_ctl_sock; 1044 out: 1045 return err; 1046 out_destroy_ctl_sock: 1047 inet_unregister_protosw(&dccp_v4_protosw); 1048 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1049 out_proto_unregister: 1050 proto_unregister(&dccp_v4_prot); 1051 goto out; 1052 } 1053 1054 static void __exit dccp_v4_exit(void) 1055 { 1056 unregister_pernet_subsys(&dccp_v4_ops); 1057 inet_unregister_protosw(&dccp_v4_protosw); 1058 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1059 proto_unregister(&dccp_v4_prot); 1060 } 1061 1062 module_init(dccp_v4_init); 1063 module_exit(dccp_v4_exit); 1064 1065 /* 1066 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1067 * values directly, Also cover the case where the protocol is not specified, 1068 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1069 */ 1070 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1071 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1072 MODULE_LICENSE("GPL"); 1073 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1074 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1075