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)); 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 newinet->inet_opt = ireq->opt; 418 ireq->opt = NULL; 419 newinet->mc_index = inet_iif(skb); 420 newinet->mc_ttl = ip_hdr(skb)->ttl; 421 newinet->inet_id = jiffies; 422 423 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 424 goto put_and_exit; 425 426 sk_setup_caps(newsk, dst); 427 428 dccp_sync_mss(newsk, dst_mtu(dst)); 429 430 if (__inet_inherit_port(sk, newsk) < 0) 431 goto put_and_exit; 432 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 433 434 return newsk; 435 436 exit_overflow: 437 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 438 exit_nonewsk: 439 dst_release(dst); 440 exit: 441 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 442 return NULL; 443 put_and_exit: 444 inet_csk_prepare_forced_close(newsk); 445 dccp_done(newsk); 446 goto exit; 447 } 448 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 449 450 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 451 struct sk_buff *skb) 452 { 453 struct rtable *rt; 454 const struct iphdr *iph = ip_hdr(skb); 455 struct flowi4 fl4 = { 456 .flowi4_oif = inet_iif(skb), 457 .daddr = iph->saddr, 458 .saddr = iph->daddr, 459 .flowi4_tos = RT_CONN_FLAGS(sk), 460 .flowi4_proto = sk->sk_protocol, 461 .fl4_sport = dccp_hdr(skb)->dccph_dport, 462 .fl4_dport = dccp_hdr(skb)->dccph_sport, 463 }; 464 465 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 466 rt = ip_route_output_flow(net, &fl4, sk); 467 if (IS_ERR(rt)) { 468 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 469 return NULL; 470 } 471 472 return &rt->dst; 473 } 474 475 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 476 { 477 int err = -1; 478 struct sk_buff *skb; 479 struct dst_entry *dst; 480 struct flowi4 fl4; 481 482 dst = inet_csk_route_req(sk, &fl4, req); 483 if (dst == NULL) 484 goto out; 485 486 skb = dccp_make_response(sk, dst, req); 487 if (skb != NULL) { 488 const struct inet_request_sock *ireq = inet_rsk(req); 489 struct dccp_hdr *dh = dccp_hdr(skb); 490 491 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 492 ireq->ir_rmt_addr); 493 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 494 ireq->ir_rmt_addr, 495 ireq->opt); 496 err = net_xmit_eval(err); 497 } 498 499 out: 500 dst_release(dst); 501 return err; 502 } 503 504 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 505 { 506 int err; 507 const struct iphdr *rxiph; 508 struct sk_buff *skb; 509 struct dst_entry *dst; 510 struct net *net = dev_net(skb_dst(rxskb)->dev); 511 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 512 513 /* Never send a reset in response to a reset. */ 514 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 515 return; 516 517 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 518 return; 519 520 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 521 if (dst == NULL) 522 return; 523 524 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 525 if (skb == NULL) 526 goto out; 527 528 rxiph = ip_hdr(rxskb); 529 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 530 rxiph->daddr); 531 skb_dst_set(skb, dst_clone(dst)); 532 533 local_bh_disable(); 534 bh_lock_sock(ctl_sk); 535 err = ip_build_and_send_pkt(skb, ctl_sk, 536 rxiph->daddr, rxiph->saddr, NULL); 537 bh_unlock_sock(ctl_sk); 538 539 if (net_xmit_eval(err) == 0) { 540 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 541 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 542 } 543 local_bh_enable(); 544 out: 545 dst_release(dst); 546 } 547 548 static void dccp_v4_reqsk_destructor(struct request_sock *req) 549 { 550 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 551 kfree(inet_rsk(req)->opt); 552 } 553 554 void dccp_syn_ack_timeout(const struct request_sock *req) 555 { 556 } 557 EXPORT_SYMBOL(dccp_syn_ack_timeout); 558 559 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 560 .family = PF_INET, 561 .obj_size = sizeof(struct dccp_request_sock), 562 .rtx_syn_ack = dccp_v4_send_response, 563 .send_ack = dccp_reqsk_send_ack, 564 .destructor = dccp_v4_reqsk_destructor, 565 .send_reset = dccp_v4_ctl_send_reset, 566 .syn_ack_timeout = dccp_syn_ack_timeout, 567 }; 568 569 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 570 { 571 struct inet_request_sock *ireq; 572 struct request_sock *req; 573 struct dccp_request_sock *dreq; 574 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 575 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 576 577 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 578 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 579 return 0; /* discard, don't send a reset here */ 580 581 if (dccp_bad_service_code(sk, service)) { 582 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 583 goto drop; 584 } 585 /* 586 * TW buckets are converted to open requests without 587 * limitations, they conserve resources and peer is 588 * evidently real one. 589 */ 590 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 591 if (inet_csk_reqsk_queue_is_full(sk)) 592 goto drop; 593 594 if (sk_acceptq_is_full(sk)) 595 goto drop; 596 597 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 598 if (req == NULL) 599 goto drop; 600 601 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 602 goto drop_and_free; 603 604 dreq = dccp_rsk(req); 605 if (dccp_parse_options(sk, dreq, skb)) 606 goto drop_and_free; 607 608 if (security_inet_conn_request(sk, skb, req)) 609 goto drop_and_free; 610 611 ireq = inet_rsk(req); 612 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 613 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 614 ireq->ireq_family = AF_INET; 615 ireq->ir_iif = sk->sk_bound_dev_if; 616 617 /* 618 * Step 3: Process LISTEN state 619 * 620 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 621 * 622 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 623 */ 624 dreq->dreq_isr = dcb->dccpd_seq; 625 dreq->dreq_gsr = dreq->dreq_isr; 626 dreq->dreq_iss = dccp_v4_init_sequence(skb); 627 dreq->dreq_gss = dreq->dreq_iss; 628 dreq->dreq_service = service; 629 630 if (dccp_v4_send_response(sk, req)) 631 goto drop_and_free; 632 633 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 634 return 0; 635 636 drop_and_free: 637 reqsk_free(req); 638 drop: 639 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 640 return -1; 641 } 642 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 643 644 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 645 { 646 struct dccp_hdr *dh = dccp_hdr(skb); 647 648 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 649 if (dccp_rcv_established(sk, skb, dh, skb->len)) 650 goto reset; 651 return 0; 652 } 653 654 /* 655 * Step 3: Process LISTEN state 656 * If P.type == Request or P contains a valid Init Cookie option, 657 * (* Must scan the packet's options to check for Init 658 * Cookies. Only Init Cookies are processed here, 659 * however; other options are processed in Step 8. This 660 * scan need only be performed if the endpoint uses Init 661 * Cookies *) 662 * (* Generate a new socket and switch to that socket *) 663 * Set S := new socket for this port pair 664 * S.state = RESPOND 665 * Choose S.ISS (initial seqno) or set from Init Cookies 666 * Initialize S.GAR := S.ISS 667 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 668 * Continue with S.state == RESPOND 669 * (* A Response packet will be generated in Step 11 *) 670 * Otherwise, 671 * Generate Reset(No Connection) unless P.type == Reset 672 * Drop packet and return 673 * 674 * NOTE: the check for the packet types is done in 675 * dccp_rcv_state_process 676 */ 677 678 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 679 goto reset; 680 return 0; 681 682 reset: 683 dccp_v4_ctl_send_reset(sk, skb); 684 kfree_skb(skb); 685 return 0; 686 } 687 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 688 689 /** 690 * dccp_invalid_packet - check for malformed packets 691 * Implements RFC 4340, 8.5: Step 1: Check header basics 692 * Packets that fail these checks are ignored and do not receive Resets. 693 */ 694 int dccp_invalid_packet(struct sk_buff *skb) 695 { 696 const struct dccp_hdr *dh; 697 unsigned int cscov; 698 u8 dccph_doff; 699 700 if (skb->pkt_type != PACKET_HOST) 701 return 1; 702 703 /* If the packet is shorter than 12 bytes, drop packet and return */ 704 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 705 DCCP_WARN("pskb_may_pull failed\n"); 706 return 1; 707 } 708 709 dh = dccp_hdr(skb); 710 711 /* If P.type is not understood, drop packet and return */ 712 if (dh->dccph_type >= DCCP_PKT_INVALID) { 713 DCCP_WARN("invalid packet type\n"); 714 return 1; 715 } 716 717 /* 718 * If P.Data Offset is too small for packet type, drop packet and return 719 */ 720 dccph_doff = dh->dccph_doff; 721 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 722 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 723 return 1; 724 } 725 /* 726 * If P.Data Offset is too too large for packet, drop packet and return 727 */ 728 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 729 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 730 return 1; 731 } 732 dh = dccp_hdr(skb); 733 /* 734 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 735 * has short sequence numbers), drop packet and return 736 */ 737 if ((dh->dccph_type < DCCP_PKT_DATA || 738 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 739 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 740 dccp_packet_name(dh->dccph_type)); 741 return 1; 742 } 743 744 /* 745 * If P.CsCov is too large for the packet size, drop packet and return. 746 * This must come _before_ checksumming (not as RFC 4340 suggests). 747 */ 748 cscov = dccp_csum_coverage(skb); 749 if (cscov > skb->len) { 750 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 751 dh->dccph_cscov, skb->len); 752 return 1; 753 } 754 755 /* If header checksum is incorrect, drop packet and return. 756 * (This step is completed in the AF-dependent functions.) */ 757 skb->csum = skb_checksum(skb, 0, cscov, 0); 758 759 return 0; 760 } 761 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 762 763 /* this is called when real data arrives */ 764 static int dccp_v4_rcv(struct sk_buff *skb) 765 { 766 const struct dccp_hdr *dh; 767 const struct iphdr *iph; 768 bool refcounted; 769 struct sock *sk; 770 int min_cov; 771 772 /* Step 1: Check header basics */ 773 774 if (dccp_invalid_packet(skb)) 775 goto discard_it; 776 777 iph = ip_hdr(skb); 778 /* Step 1: If header checksum is incorrect, drop packet and return */ 779 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 780 DCCP_WARN("dropped packet with invalid checksum\n"); 781 goto discard_it; 782 } 783 784 dh = dccp_hdr(skb); 785 786 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 787 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 788 789 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 790 dccp_packet_name(dh->dccph_type), 791 &iph->saddr, ntohs(dh->dccph_sport), 792 &iph->daddr, ntohs(dh->dccph_dport), 793 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 794 795 if (dccp_packet_without_ack(skb)) { 796 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 797 dccp_pr_debug_cat("\n"); 798 } else { 799 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 800 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 801 DCCP_SKB_CB(skb)->dccpd_ack_seq); 802 } 803 804 lookup: 805 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 806 dh->dccph_sport, dh->dccph_dport, &refcounted); 807 if (!sk) { 808 dccp_pr_debug("failed to look up flow ID in table and " 809 "get corresponding socket\n"); 810 goto no_dccp_socket; 811 } 812 813 /* 814 * Step 2: 815 * ... or S.state == TIMEWAIT, 816 * Generate Reset(No Connection) unless P.type == Reset 817 * Drop packet and return 818 */ 819 if (sk->sk_state == DCCP_TIME_WAIT) { 820 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 821 inet_twsk_put(inet_twsk(sk)); 822 goto no_dccp_socket; 823 } 824 825 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 826 struct request_sock *req = inet_reqsk(sk); 827 struct sock *nsk; 828 829 sk = req->rsk_listener; 830 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 831 inet_csk_reqsk_queue_drop_and_put(sk, req); 832 goto lookup; 833 } 834 sock_hold(sk); 835 refcounted = true; 836 nsk = dccp_check_req(sk, skb, req); 837 if (!nsk) { 838 reqsk_put(req); 839 goto discard_and_relse; 840 } 841 if (nsk == sk) { 842 reqsk_put(req); 843 } else if (dccp_child_process(sk, nsk, skb)) { 844 dccp_v4_ctl_send_reset(sk, skb); 845 goto discard_and_relse; 846 } else { 847 sock_put(sk); 848 return 0; 849 } 850 } 851 /* 852 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 853 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 854 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 855 */ 856 min_cov = dccp_sk(sk)->dccps_pcrlen; 857 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 858 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 859 dh->dccph_cscov, min_cov); 860 /* FIXME: "Such packets SHOULD be reported using Data Dropped 861 * options (Section 11.7) with Drop Code 0, Protocol 862 * Constraints." */ 863 goto discard_and_relse; 864 } 865 866 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 867 goto discard_and_relse; 868 nf_reset(skb); 869 870 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 871 872 no_dccp_socket: 873 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 874 goto discard_it; 875 /* 876 * Step 2: 877 * If no socket ... 878 * Generate Reset(No Connection) unless P.type == Reset 879 * Drop packet and return 880 */ 881 if (dh->dccph_type != DCCP_PKT_RESET) { 882 DCCP_SKB_CB(skb)->dccpd_reset_code = 883 DCCP_RESET_CODE_NO_CONNECTION; 884 dccp_v4_ctl_send_reset(sk, skb); 885 } 886 887 discard_it: 888 kfree_skb(skb); 889 return 0; 890 891 discard_and_relse: 892 if (refcounted) 893 sock_put(sk); 894 goto discard_it; 895 } 896 897 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 898 .queue_xmit = ip_queue_xmit, 899 .send_check = dccp_v4_send_check, 900 .rebuild_header = inet_sk_rebuild_header, 901 .conn_request = dccp_v4_conn_request, 902 .syn_recv_sock = dccp_v4_request_recv_sock, 903 .net_header_len = sizeof(struct iphdr), 904 .setsockopt = ip_setsockopt, 905 .getsockopt = ip_getsockopt, 906 .addr2sockaddr = inet_csk_addr2sockaddr, 907 .sockaddr_len = sizeof(struct sockaddr_in), 908 #ifdef CONFIG_COMPAT 909 .compat_setsockopt = compat_ip_setsockopt, 910 .compat_getsockopt = compat_ip_getsockopt, 911 #endif 912 }; 913 914 static int dccp_v4_init_sock(struct sock *sk) 915 { 916 static __u8 dccp_v4_ctl_sock_initialized; 917 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 918 919 if (err == 0) { 920 if (unlikely(!dccp_v4_ctl_sock_initialized)) 921 dccp_v4_ctl_sock_initialized = 1; 922 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 923 } 924 925 return err; 926 } 927 928 static struct timewait_sock_ops dccp_timewait_sock_ops = { 929 .twsk_obj_size = sizeof(struct inet_timewait_sock), 930 }; 931 932 static struct proto dccp_v4_prot = { 933 .name = "DCCP", 934 .owner = THIS_MODULE, 935 .close = dccp_close, 936 .connect = dccp_v4_connect, 937 .disconnect = dccp_disconnect, 938 .ioctl = dccp_ioctl, 939 .init = dccp_v4_init_sock, 940 .setsockopt = dccp_setsockopt, 941 .getsockopt = dccp_getsockopt, 942 .sendmsg = dccp_sendmsg, 943 .recvmsg = dccp_recvmsg, 944 .backlog_rcv = dccp_v4_do_rcv, 945 .hash = inet_hash, 946 .unhash = inet_unhash, 947 .accept = inet_csk_accept, 948 .get_port = inet_csk_get_port, 949 .shutdown = dccp_shutdown, 950 .destroy = dccp_destroy_sock, 951 .orphan_count = &dccp_orphan_count, 952 .max_header = MAX_DCCP_HEADER, 953 .obj_size = sizeof(struct dccp_sock), 954 .slab_flags = SLAB_TYPESAFE_BY_RCU, 955 .rsk_prot = &dccp_request_sock_ops, 956 .twsk_prot = &dccp_timewait_sock_ops, 957 .h.hashinfo = &dccp_hashinfo, 958 #ifdef CONFIG_COMPAT 959 .compat_setsockopt = compat_dccp_setsockopt, 960 .compat_getsockopt = compat_dccp_getsockopt, 961 #endif 962 }; 963 964 static const struct net_protocol dccp_v4_protocol = { 965 .handler = dccp_v4_rcv, 966 .err_handler = dccp_v4_err, 967 .no_policy = 1, 968 .netns_ok = 1, 969 .icmp_strict_tag_validation = 1, 970 }; 971 972 static const struct proto_ops inet_dccp_ops = { 973 .family = PF_INET, 974 .owner = THIS_MODULE, 975 .release = inet_release, 976 .bind = inet_bind, 977 .connect = inet_stream_connect, 978 .socketpair = sock_no_socketpair, 979 .accept = inet_accept, 980 .getname = inet_getname, 981 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 982 .poll = dccp_poll, 983 .ioctl = inet_ioctl, 984 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 985 .listen = inet_dccp_listen, 986 .shutdown = inet_shutdown, 987 .setsockopt = sock_common_setsockopt, 988 .getsockopt = sock_common_getsockopt, 989 .sendmsg = inet_sendmsg, 990 .recvmsg = sock_common_recvmsg, 991 .mmap = sock_no_mmap, 992 .sendpage = sock_no_sendpage, 993 #ifdef CONFIG_COMPAT 994 .compat_setsockopt = compat_sock_common_setsockopt, 995 .compat_getsockopt = compat_sock_common_getsockopt, 996 #endif 997 }; 998 999 static struct inet_protosw dccp_v4_protosw = { 1000 .type = SOCK_DCCP, 1001 .protocol = IPPROTO_DCCP, 1002 .prot = &dccp_v4_prot, 1003 .ops = &inet_dccp_ops, 1004 .flags = INET_PROTOSW_ICSK, 1005 }; 1006 1007 static int __net_init dccp_v4_init_net(struct net *net) 1008 { 1009 if (dccp_hashinfo.bhash == NULL) 1010 return -ESOCKTNOSUPPORT; 1011 1012 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1013 SOCK_DCCP, IPPROTO_DCCP, net); 1014 } 1015 1016 static void __net_exit dccp_v4_exit_net(struct net *net) 1017 { 1018 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1019 } 1020 1021 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1022 { 1023 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1024 } 1025 1026 static struct pernet_operations dccp_v4_ops = { 1027 .init = dccp_v4_init_net, 1028 .exit = dccp_v4_exit_net, 1029 .exit_batch = dccp_v4_exit_batch, 1030 }; 1031 1032 static int __init dccp_v4_init(void) 1033 { 1034 int err = proto_register(&dccp_v4_prot, 1); 1035 1036 if (err) 1037 goto out; 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 1045 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1046 if (err) 1047 goto out_proto_unregister; 1048 1049 out: 1050 return err; 1051 out_proto_unregister: 1052 unregister_pernet_subsys(&dccp_v4_ops); 1053 out_destroy_ctl_sock: 1054 inet_unregister_protosw(&dccp_v4_protosw); 1055 proto_unregister(&dccp_v4_prot); 1056 goto out; 1057 } 1058 1059 static void __exit dccp_v4_exit(void) 1060 { 1061 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1062 unregister_pernet_subsys(&dccp_v4_ops); 1063 inet_unregister_protosw(&dccp_v4_protosw); 1064 proto_unregister(&dccp_v4_prot); 1065 } 1066 1067 module_init(dccp_v4_init); 1068 module_exit(dccp_v4_exit); 1069 1070 /* 1071 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1072 * values directly, Also cover the case where the protocol is not specified, 1073 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1074 */ 1075 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1076 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1077 MODULE_LICENSE("GPL"); 1078 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1079 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1080