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; 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 /* Only need dccph_dport & dccph_sport which are the first 249 * 4 bytes in dccp header. 250 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 251 */ 252 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 253 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 254 dh = (struct dccp_hdr *)(skb->data + offset); 255 256 sk = __inet_lookup_established(net, &dccp_hashinfo, 257 iph->daddr, dh->dccph_dport, 258 iph->saddr, ntohs(dh->dccph_sport), 259 inet_iif(skb), 0); 260 if (!sk) { 261 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 262 return; 263 } 264 265 if (sk->sk_state == DCCP_TIME_WAIT) { 266 inet_twsk_put(inet_twsk(sk)); 267 return; 268 } 269 seq = dccp_hdr_seq(dh); 270 if (sk->sk_state == DCCP_NEW_SYN_RECV) 271 return dccp_req_err(sk, seq); 272 273 bh_lock_sock(sk); 274 /* If too many ICMPs get dropped on busy 275 * servers this needs to be solved differently. 276 */ 277 if (sock_owned_by_user(sk)) 278 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 279 280 if (sk->sk_state == DCCP_CLOSED) 281 goto out; 282 283 dp = dccp_sk(sk); 284 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 285 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 286 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 287 goto out; 288 } 289 290 switch (type) { 291 case ICMP_REDIRECT: 292 if (!sock_owned_by_user(sk)) 293 dccp_do_redirect(skb, sk); 294 goto out; 295 case ICMP_SOURCE_QUENCH: 296 /* Just silently ignore these. */ 297 goto out; 298 case ICMP_PARAMETERPROB: 299 err = EPROTO; 300 break; 301 case ICMP_DEST_UNREACH: 302 if (code > NR_ICMP_UNREACH) 303 goto out; 304 305 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 306 if (!sock_owned_by_user(sk)) 307 dccp_do_pmtu_discovery(sk, iph, info); 308 goto out; 309 } 310 311 err = icmp_err_convert[code].errno; 312 break; 313 case ICMP_TIME_EXCEEDED: 314 err = EHOSTUNREACH; 315 break; 316 default: 317 goto out; 318 } 319 320 switch (sk->sk_state) { 321 case DCCP_REQUESTING: 322 case DCCP_RESPOND: 323 if (!sock_owned_by_user(sk)) { 324 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 325 sk->sk_err = err; 326 327 sk->sk_error_report(sk); 328 329 dccp_done(sk); 330 } else 331 sk->sk_err_soft = err; 332 goto out; 333 } 334 335 /* If we've already connected we will keep trying 336 * until we time out, or the user gives up. 337 * 338 * rfc1122 4.2.3.9 allows to consider as hard errors 339 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 340 * but it is obsoleted by pmtu discovery). 341 * 342 * Note, that in modern internet, where routing is unreliable 343 * and in each dark corner broken firewalls sit, sending random 344 * errors ordered by their masters even this two messages finally lose 345 * their original sense (even Linux sends invalid PORT_UNREACHs) 346 * 347 * Now we are in compliance with RFCs. 348 * --ANK (980905) 349 */ 350 351 inet = inet_sk(sk); 352 if (!sock_owned_by_user(sk) && inet->recverr) { 353 sk->sk_err = err; 354 sk->sk_error_report(sk); 355 } else /* Only an error on timeout */ 356 sk->sk_err_soft = err; 357 out: 358 bh_unlock_sock(sk); 359 sock_put(sk); 360 } 361 362 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 363 __be32 src, __be32 dst) 364 { 365 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 366 } 367 368 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 369 { 370 const struct inet_sock *inet = inet_sk(sk); 371 struct dccp_hdr *dh = dccp_hdr(skb); 372 373 dccp_csum_outgoing(skb); 374 dh->dccph_checksum = dccp_v4_csum_finish(skb, 375 inet->inet_saddr, 376 inet->inet_daddr); 377 } 378 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 379 380 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 381 { 382 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 383 ip_hdr(skb)->saddr, 384 dccp_hdr(skb)->dccph_dport, 385 dccp_hdr(skb)->dccph_sport); 386 } 387 388 /* 389 * The three way handshake has completed - we got a valid ACK or DATAACK - 390 * now create the new socket. 391 * 392 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 393 */ 394 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 395 struct sk_buff *skb, 396 struct request_sock *req, 397 struct dst_entry *dst, 398 struct request_sock *req_unhash, 399 bool *own_req) 400 { 401 struct inet_request_sock *ireq; 402 struct inet_sock *newinet; 403 struct sock *newsk; 404 405 if (sk_acceptq_is_full(sk)) 406 goto exit_overflow; 407 408 newsk = dccp_create_openreq_child(sk, req, skb); 409 if (newsk == NULL) 410 goto exit_nonewsk; 411 412 newinet = inet_sk(newsk); 413 ireq = inet_rsk(req); 414 sk_daddr_set(newsk, ireq->ir_rmt_addr); 415 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 416 newinet->inet_saddr = ireq->ir_loc_addr; 417 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 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 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 432 if (*own_req) 433 ireq->ireq_opt = NULL; 434 else 435 newinet->inet_opt = NULL; 436 return newsk; 437 438 exit_overflow: 439 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 440 exit_nonewsk: 441 dst_release(dst); 442 exit: 443 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 444 return NULL; 445 put_and_exit: 446 newinet->inet_opt = NULL; 447 inet_csk_prepare_forced_close(newsk); 448 dccp_done(newsk); 449 goto exit; 450 } 451 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 452 453 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 454 struct sk_buff *skb) 455 { 456 struct rtable *rt; 457 const struct iphdr *iph = ip_hdr(skb); 458 struct flowi4 fl4 = { 459 .flowi4_oif = inet_iif(skb), 460 .daddr = iph->saddr, 461 .saddr = iph->daddr, 462 .flowi4_tos = RT_CONN_FLAGS(sk), 463 .flowi4_proto = sk->sk_protocol, 464 .fl4_sport = dccp_hdr(skb)->dccph_dport, 465 .fl4_dport = dccp_hdr(skb)->dccph_sport, 466 }; 467 468 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 469 rt = ip_route_output_flow(net, &fl4, sk); 470 if (IS_ERR(rt)) { 471 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 472 return NULL; 473 } 474 475 return &rt->dst; 476 } 477 478 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 479 { 480 int err = -1; 481 struct sk_buff *skb; 482 struct dst_entry *dst; 483 struct flowi4 fl4; 484 485 dst = inet_csk_route_req(sk, &fl4, req); 486 if (dst == NULL) 487 goto out; 488 489 skb = dccp_make_response(sk, dst, req); 490 if (skb != NULL) { 491 const struct inet_request_sock *ireq = inet_rsk(req); 492 struct dccp_hdr *dh = dccp_hdr(skb); 493 494 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 495 ireq->ir_rmt_addr); 496 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 497 ireq->ir_rmt_addr, 498 ireq_opt_deref(ireq)); 499 err = net_xmit_eval(err); 500 } 501 502 out: 503 dst_release(dst); 504 return err; 505 } 506 507 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 508 { 509 int err; 510 const struct iphdr *rxiph; 511 struct sk_buff *skb; 512 struct dst_entry *dst; 513 struct net *net = dev_net(skb_dst(rxskb)->dev); 514 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 515 516 /* Never send a reset in response to a reset. */ 517 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 518 return; 519 520 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 521 return; 522 523 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 524 if (dst == NULL) 525 return; 526 527 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 528 if (skb == NULL) 529 goto out; 530 531 rxiph = ip_hdr(rxskb); 532 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 533 rxiph->daddr); 534 skb_dst_set(skb, dst_clone(dst)); 535 536 local_bh_disable(); 537 bh_lock_sock(ctl_sk); 538 err = ip_build_and_send_pkt(skb, ctl_sk, 539 rxiph->daddr, rxiph->saddr, NULL); 540 bh_unlock_sock(ctl_sk); 541 542 if (net_xmit_eval(err) == 0) { 543 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 544 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 545 } 546 local_bh_enable(); 547 out: 548 dst_release(dst); 549 } 550 551 static void dccp_v4_reqsk_destructor(struct request_sock *req) 552 { 553 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 554 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 555 } 556 557 void dccp_syn_ack_timeout(const struct request_sock *req) 558 { 559 } 560 EXPORT_SYMBOL(dccp_syn_ack_timeout); 561 562 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 563 .family = PF_INET, 564 .obj_size = sizeof(struct dccp_request_sock), 565 .rtx_syn_ack = dccp_v4_send_response, 566 .send_ack = dccp_reqsk_send_ack, 567 .destructor = dccp_v4_reqsk_destructor, 568 .send_reset = dccp_v4_ctl_send_reset, 569 .syn_ack_timeout = dccp_syn_ack_timeout, 570 }; 571 572 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 573 { 574 struct inet_request_sock *ireq; 575 struct request_sock *req; 576 struct dccp_request_sock *dreq; 577 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 578 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 579 580 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 581 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 582 return 0; /* discard, don't send a reset here */ 583 584 if (dccp_bad_service_code(sk, service)) { 585 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 586 goto drop; 587 } 588 /* 589 * TW buckets are converted to open requests without 590 * limitations, they conserve resources and peer is 591 * evidently real one. 592 */ 593 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 594 if (inet_csk_reqsk_queue_is_full(sk)) 595 goto drop; 596 597 if (sk_acceptq_is_full(sk)) 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 reqsk_put(req); 638 return 0; 639 640 drop_and_free: 641 reqsk_free(req); 642 drop: 643 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 644 return -1; 645 } 646 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 647 648 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 649 { 650 struct dccp_hdr *dh = dccp_hdr(skb); 651 652 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 653 if (dccp_rcv_established(sk, skb, dh, skb->len)) 654 goto reset; 655 return 0; 656 } 657 658 /* 659 * Step 3: Process LISTEN state 660 * If P.type == Request or P contains a valid Init Cookie option, 661 * (* Must scan the packet's options to check for Init 662 * Cookies. Only Init Cookies are processed here, 663 * however; other options are processed in Step 8. This 664 * scan need only be performed if the endpoint uses Init 665 * Cookies *) 666 * (* Generate a new socket and switch to that socket *) 667 * Set S := new socket for this port pair 668 * S.state = RESPOND 669 * Choose S.ISS (initial seqno) or set from Init Cookies 670 * Initialize S.GAR := S.ISS 671 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 672 * Continue with S.state == RESPOND 673 * (* A Response packet will be generated in Step 11 *) 674 * Otherwise, 675 * Generate Reset(No Connection) unless P.type == Reset 676 * Drop packet and return 677 * 678 * NOTE: the check for the packet types is done in 679 * dccp_rcv_state_process 680 */ 681 682 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 683 goto reset; 684 return 0; 685 686 reset: 687 dccp_v4_ctl_send_reset(sk, skb); 688 kfree_skb(skb); 689 return 0; 690 } 691 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 692 693 /** 694 * dccp_invalid_packet - check for malformed packets 695 * Implements RFC 4340, 8.5: Step 1: Check header basics 696 * Packets that fail these checks are ignored and do not receive Resets. 697 */ 698 int dccp_invalid_packet(struct sk_buff *skb) 699 { 700 const struct dccp_hdr *dh; 701 unsigned int cscov; 702 u8 dccph_doff; 703 704 if (skb->pkt_type != PACKET_HOST) 705 return 1; 706 707 /* If the packet is shorter than 12 bytes, drop packet and return */ 708 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 709 DCCP_WARN("pskb_may_pull failed\n"); 710 return 1; 711 } 712 713 dh = dccp_hdr(skb); 714 715 /* If P.type is not understood, drop packet and return */ 716 if (dh->dccph_type >= DCCP_PKT_INVALID) { 717 DCCP_WARN("invalid packet type\n"); 718 return 1; 719 } 720 721 /* 722 * If P.Data Offset is too small for packet type, drop packet and return 723 */ 724 dccph_doff = dh->dccph_doff; 725 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 726 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 727 return 1; 728 } 729 /* 730 * If P.Data Offset is too too large for packet, drop packet and return 731 */ 732 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 733 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 734 return 1; 735 } 736 dh = dccp_hdr(skb); 737 /* 738 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 739 * has short sequence numbers), drop packet and return 740 */ 741 if ((dh->dccph_type < DCCP_PKT_DATA || 742 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 743 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 744 dccp_packet_name(dh->dccph_type)); 745 return 1; 746 } 747 748 /* 749 * If P.CsCov is too large for the packet size, drop packet and return. 750 * This must come _before_ checksumming (not as RFC 4340 suggests). 751 */ 752 cscov = dccp_csum_coverage(skb); 753 if (cscov > skb->len) { 754 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 755 dh->dccph_cscov, skb->len); 756 return 1; 757 } 758 759 /* If header checksum is incorrect, drop packet and return. 760 * (This step is completed in the AF-dependent functions.) */ 761 skb->csum = skb_checksum(skb, 0, cscov, 0); 762 763 return 0; 764 } 765 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 766 767 /* this is called when real data arrives */ 768 static int dccp_v4_rcv(struct sk_buff *skb) 769 { 770 const struct dccp_hdr *dh; 771 const struct iphdr *iph; 772 bool refcounted; 773 struct sock *sk; 774 int min_cov; 775 776 /* Step 1: Check header basics */ 777 778 if (dccp_invalid_packet(skb)) 779 goto discard_it; 780 781 iph = ip_hdr(skb); 782 /* Step 1: If header checksum is incorrect, drop packet and return */ 783 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 784 DCCP_WARN("dropped packet with invalid checksum\n"); 785 goto discard_it; 786 } 787 788 dh = dccp_hdr(skb); 789 790 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 791 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 792 793 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 794 dccp_packet_name(dh->dccph_type), 795 &iph->saddr, ntohs(dh->dccph_sport), 796 &iph->daddr, ntohs(dh->dccph_dport), 797 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 798 799 if (dccp_packet_without_ack(skb)) { 800 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 801 dccp_pr_debug_cat("\n"); 802 } else { 803 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 804 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 805 DCCP_SKB_CB(skb)->dccpd_ack_seq); 806 } 807 808 lookup: 809 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 810 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 811 if (!sk) { 812 dccp_pr_debug("failed to look up flow ID in table and " 813 "get corresponding socket\n"); 814 goto no_dccp_socket; 815 } 816 817 /* 818 * Step 2: 819 * ... or S.state == TIMEWAIT, 820 * Generate Reset(No Connection) unless P.type == Reset 821 * Drop packet and return 822 */ 823 if (sk->sk_state == DCCP_TIME_WAIT) { 824 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 825 inet_twsk_put(inet_twsk(sk)); 826 goto no_dccp_socket; 827 } 828 829 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 830 struct request_sock *req = inet_reqsk(sk); 831 struct sock *nsk; 832 833 sk = req->rsk_listener; 834 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 835 inet_csk_reqsk_queue_drop_and_put(sk, req); 836 goto lookup; 837 } 838 sock_hold(sk); 839 refcounted = true; 840 nsk = dccp_check_req(sk, skb, req); 841 if (!nsk) { 842 reqsk_put(req); 843 goto discard_and_relse; 844 } 845 if (nsk == sk) { 846 reqsk_put(req); 847 } else if (dccp_child_process(sk, nsk, skb)) { 848 dccp_v4_ctl_send_reset(sk, skb); 849 goto discard_and_relse; 850 } else { 851 sock_put(sk); 852 return 0; 853 } 854 } 855 /* 856 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 857 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 858 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 859 */ 860 min_cov = dccp_sk(sk)->dccps_pcrlen; 861 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 862 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 863 dh->dccph_cscov, min_cov); 864 /* FIXME: "Such packets SHOULD be reported using Data Dropped 865 * options (Section 11.7) with Drop Code 0, Protocol 866 * Constraints." */ 867 goto discard_and_relse; 868 } 869 870 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 871 goto discard_and_relse; 872 nf_reset(skb); 873 874 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 875 876 no_dccp_socket: 877 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 878 goto discard_it; 879 /* 880 * Step 2: 881 * If no socket ... 882 * Generate Reset(No Connection) unless P.type == Reset 883 * Drop packet and return 884 */ 885 if (dh->dccph_type != DCCP_PKT_RESET) { 886 DCCP_SKB_CB(skb)->dccpd_reset_code = 887 DCCP_RESET_CODE_NO_CONNECTION; 888 dccp_v4_ctl_send_reset(sk, skb); 889 } 890 891 discard_it: 892 kfree_skb(skb); 893 return 0; 894 895 discard_and_relse: 896 if (refcounted) 897 sock_put(sk); 898 goto discard_it; 899 } 900 901 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 902 .queue_xmit = ip_queue_xmit, 903 .send_check = dccp_v4_send_check, 904 .rebuild_header = inet_sk_rebuild_header, 905 .conn_request = dccp_v4_conn_request, 906 .syn_recv_sock = dccp_v4_request_recv_sock, 907 .net_header_len = sizeof(struct iphdr), 908 .setsockopt = ip_setsockopt, 909 .getsockopt = ip_getsockopt, 910 .addr2sockaddr = inet_csk_addr2sockaddr, 911 .sockaddr_len = sizeof(struct sockaddr_in), 912 #ifdef CONFIG_COMPAT 913 .compat_setsockopt = compat_ip_setsockopt, 914 .compat_getsockopt = compat_ip_getsockopt, 915 #endif 916 }; 917 918 static int dccp_v4_init_sock(struct sock *sk) 919 { 920 static __u8 dccp_v4_ctl_sock_initialized; 921 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 922 923 if (err == 0) { 924 if (unlikely(!dccp_v4_ctl_sock_initialized)) 925 dccp_v4_ctl_sock_initialized = 1; 926 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 927 } 928 929 return err; 930 } 931 932 static struct timewait_sock_ops dccp_timewait_sock_ops = { 933 .twsk_obj_size = sizeof(struct inet_timewait_sock), 934 }; 935 936 static struct proto dccp_v4_prot = { 937 .name = "DCCP", 938 .owner = THIS_MODULE, 939 .close = dccp_close, 940 .connect = dccp_v4_connect, 941 .disconnect = dccp_disconnect, 942 .ioctl = dccp_ioctl, 943 .init = dccp_v4_init_sock, 944 .setsockopt = dccp_setsockopt, 945 .getsockopt = dccp_getsockopt, 946 .sendmsg = dccp_sendmsg, 947 .recvmsg = dccp_recvmsg, 948 .backlog_rcv = dccp_v4_do_rcv, 949 .hash = inet_hash, 950 .unhash = inet_unhash, 951 .accept = inet_csk_accept, 952 .get_port = inet_csk_get_port, 953 .shutdown = dccp_shutdown, 954 .destroy = dccp_destroy_sock, 955 .orphan_count = &dccp_orphan_count, 956 .max_header = MAX_DCCP_HEADER, 957 .obj_size = sizeof(struct dccp_sock), 958 .slab_flags = SLAB_TYPESAFE_BY_RCU, 959 .rsk_prot = &dccp_request_sock_ops, 960 .twsk_prot = &dccp_timewait_sock_ops, 961 .h.hashinfo = &dccp_hashinfo, 962 #ifdef CONFIG_COMPAT 963 .compat_setsockopt = compat_dccp_setsockopt, 964 .compat_getsockopt = compat_dccp_getsockopt, 965 #endif 966 }; 967 968 static const struct net_protocol dccp_v4_protocol = { 969 .handler = dccp_v4_rcv, 970 .err_handler = dccp_v4_err, 971 .no_policy = 1, 972 .netns_ok = 1, 973 .icmp_strict_tag_validation = 1, 974 }; 975 976 static const struct proto_ops inet_dccp_ops = { 977 .family = PF_INET, 978 .owner = THIS_MODULE, 979 .release = inet_release, 980 .bind = inet_bind, 981 .connect = inet_stream_connect, 982 .socketpair = sock_no_socketpair, 983 .accept = inet_accept, 984 .getname = inet_getname, 985 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 986 .poll = dccp_poll, 987 .ioctl = inet_ioctl, 988 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 989 .listen = inet_dccp_listen, 990 .shutdown = inet_shutdown, 991 .setsockopt = sock_common_setsockopt, 992 .getsockopt = sock_common_getsockopt, 993 .sendmsg = inet_sendmsg, 994 .recvmsg = sock_common_recvmsg, 995 .mmap = sock_no_mmap, 996 .sendpage = sock_no_sendpage, 997 #ifdef CONFIG_COMPAT 998 .compat_setsockopt = compat_sock_common_setsockopt, 999 .compat_getsockopt = compat_sock_common_getsockopt, 1000 #endif 1001 }; 1002 1003 static struct inet_protosw dccp_v4_protosw = { 1004 .type = SOCK_DCCP, 1005 .protocol = IPPROTO_DCCP, 1006 .prot = &dccp_v4_prot, 1007 .ops = &inet_dccp_ops, 1008 .flags = INET_PROTOSW_ICSK, 1009 }; 1010 1011 static int __net_init dccp_v4_init_net(struct net *net) 1012 { 1013 if (dccp_hashinfo.bhash == NULL) 1014 return -ESOCKTNOSUPPORT; 1015 1016 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1017 SOCK_DCCP, IPPROTO_DCCP, net); 1018 } 1019 1020 static void __net_exit dccp_v4_exit_net(struct net *net) 1021 { 1022 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1023 } 1024 1025 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1026 { 1027 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1028 } 1029 1030 static struct pernet_operations dccp_v4_ops = { 1031 .init = dccp_v4_init_net, 1032 .exit = dccp_v4_exit_net, 1033 .exit_batch = dccp_v4_exit_batch, 1034 }; 1035 1036 static int __init dccp_v4_init(void) 1037 { 1038 int err = proto_register(&dccp_v4_prot, 1); 1039 1040 if (err) 1041 goto out; 1042 1043 inet_register_protosw(&dccp_v4_protosw); 1044 1045 err = register_pernet_subsys(&dccp_v4_ops); 1046 if (err) 1047 goto out_destroy_ctl_sock; 1048 1049 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1050 if (err) 1051 goto out_proto_unregister; 1052 1053 out: 1054 return err; 1055 out_proto_unregister: 1056 unregister_pernet_subsys(&dccp_v4_ops); 1057 out_destroy_ctl_sock: 1058 inet_unregister_protosw(&dccp_v4_protosw); 1059 proto_unregister(&dccp_v4_prot); 1060 goto out; 1061 } 1062 1063 static void __exit dccp_v4_exit(void) 1064 { 1065 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1066 unregister_pernet_subsys(&dccp_v4_ops); 1067 inet_unregister_protosw(&dccp_v4_protosw); 1068 proto_unregister(&dccp_v4_prot); 1069 } 1070 1071 module_init(dccp_v4_init); 1072 module_exit(dccp_v4_exit); 1073 1074 /* 1075 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1076 * values directly, Also cover the case where the protocol is not specified, 1077 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1078 */ 1079 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1080 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1081 MODULE_LICENSE("GPL"); 1082 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1083 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1084