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 int 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 -ENOENT; 263 } 264 265 if (sk->sk_state == DCCP_TIME_WAIT) { 266 inet_twsk_put(inet_twsk(sk)); 267 return 0; 268 } 269 seq = dccp_hdr_seq(dh); 270 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 271 dccp_req_err(sk, seq); 272 return 0; 273 } 274 275 bh_lock_sock(sk); 276 /* If too many ICMPs get dropped on busy 277 * servers this needs to be solved differently. 278 */ 279 if (sock_owned_by_user(sk)) 280 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 281 282 if (sk->sk_state == DCCP_CLOSED) 283 goto out; 284 285 dp = dccp_sk(sk); 286 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 287 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 288 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 289 goto out; 290 } 291 292 switch (type) { 293 case ICMP_REDIRECT: 294 if (!sock_owned_by_user(sk)) 295 dccp_do_redirect(skb, sk); 296 goto out; 297 case ICMP_SOURCE_QUENCH: 298 /* Just silently ignore these. */ 299 goto out; 300 case ICMP_PARAMETERPROB: 301 err = EPROTO; 302 break; 303 case ICMP_DEST_UNREACH: 304 if (code > NR_ICMP_UNREACH) 305 goto out; 306 307 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 308 if (!sock_owned_by_user(sk)) 309 dccp_do_pmtu_discovery(sk, iph, info); 310 goto out; 311 } 312 313 err = icmp_err_convert[code].errno; 314 break; 315 case ICMP_TIME_EXCEEDED: 316 err = EHOSTUNREACH; 317 break; 318 default: 319 goto out; 320 } 321 322 switch (sk->sk_state) { 323 case DCCP_REQUESTING: 324 case DCCP_RESPOND: 325 if (!sock_owned_by_user(sk)) { 326 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 327 sk->sk_err = err; 328 329 sk->sk_error_report(sk); 330 331 dccp_done(sk); 332 } else 333 sk->sk_err_soft = err; 334 goto out; 335 } 336 337 /* If we've already connected we will keep trying 338 * until we time out, or the user gives up. 339 * 340 * rfc1122 4.2.3.9 allows to consider as hard errors 341 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 342 * but it is obsoleted by pmtu discovery). 343 * 344 * Note, that in modern internet, where routing is unreliable 345 * and in each dark corner broken firewalls sit, sending random 346 * errors ordered by their masters even this two messages finally lose 347 * their original sense (even Linux sends invalid PORT_UNREACHs) 348 * 349 * Now we are in compliance with RFCs. 350 * --ANK (980905) 351 */ 352 353 inet = inet_sk(sk); 354 if (!sock_owned_by_user(sk) && inet->recverr) { 355 sk->sk_err = err; 356 sk->sk_error_report(sk); 357 } else /* Only an error on timeout */ 358 sk->sk_err_soft = err; 359 out: 360 bh_unlock_sock(sk); 361 sock_put(sk); 362 return 0; 363 } 364 365 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 366 __be32 src, __be32 dst) 367 { 368 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 369 } 370 371 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 372 { 373 const struct inet_sock *inet = inet_sk(sk); 374 struct dccp_hdr *dh = dccp_hdr(skb); 375 376 dccp_csum_outgoing(skb); 377 dh->dccph_checksum = dccp_v4_csum_finish(skb, 378 inet->inet_saddr, 379 inet->inet_daddr); 380 } 381 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 382 383 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 384 { 385 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 386 ip_hdr(skb)->saddr, 387 dccp_hdr(skb)->dccph_dport, 388 dccp_hdr(skb)->dccph_sport); 389 } 390 391 /* 392 * The three way handshake has completed - we got a valid ACK or DATAACK - 393 * now create the new socket. 394 * 395 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 396 */ 397 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 398 struct sk_buff *skb, 399 struct request_sock *req, 400 struct dst_entry *dst, 401 struct request_sock *req_unhash, 402 bool *own_req) 403 { 404 struct inet_request_sock *ireq; 405 struct inet_sock *newinet; 406 struct sock *newsk; 407 408 if (sk_acceptq_is_full(sk)) 409 goto exit_overflow; 410 411 newsk = dccp_create_openreq_child(sk, req, skb); 412 if (newsk == NULL) 413 goto exit_nonewsk; 414 415 newinet = inet_sk(newsk); 416 ireq = inet_rsk(req); 417 sk_daddr_set(newsk, ireq->ir_rmt_addr); 418 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 419 newinet->inet_saddr = ireq->ir_loc_addr; 420 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 421 newinet->mc_index = inet_iif(skb); 422 newinet->mc_ttl = ip_hdr(skb)->ttl; 423 newinet->inet_id = jiffies; 424 425 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 426 goto put_and_exit; 427 428 sk_setup_caps(newsk, dst); 429 430 dccp_sync_mss(newsk, dst_mtu(dst)); 431 432 if (__inet_inherit_port(sk, newsk) < 0) 433 goto put_and_exit; 434 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 435 if (*own_req) 436 ireq->ireq_opt = NULL; 437 else 438 newinet->inet_opt = NULL; 439 return newsk; 440 441 exit_overflow: 442 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 443 exit_nonewsk: 444 dst_release(dst); 445 exit: 446 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 447 return NULL; 448 put_and_exit: 449 newinet->inet_opt = NULL; 450 inet_csk_prepare_forced_close(newsk); 451 dccp_done(newsk); 452 goto exit; 453 } 454 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 455 456 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 457 struct sk_buff *skb) 458 { 459 struct rtable *rt; 460 const struct iphdr *iph = ip_hdr(skb); 461 struct flowi4 fl4 = { 462 .flowi4_oif = inet_iif(skb), 463 .daddr = iph->saddr, 464 .saddr = iph->daddr, 465 .flowi4_tos = RT_CONN_FLAGS(sk), 466 .flowi4_proto = sk->sk_protocol, 467 .fl4_sport = dccp_hdr(skb)->dccph_dport, 468 .fl4_dport = dccp_hdr(skb)->dccph_sport, 469 }; 470 471 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 472 rt = ip_route_output_flow(net, &fl4, sk); 473 if (IS_ERR(rt)) { 474 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 475 return NULL; 476 } 477 478 return &rt->dst; 479 } 480 481 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 482 { 483 int err = -1; 484 struct sk_buff *skb; 485 struct dst_entry *dst; 486 struct flowi4 fl4; 487 488 dst = inet_csk_route_req(sk, &fl4, req); 489 if (dst == NULL) 490 goto out; 491 492 skb = dccp_make_response(sk, dst, req); 493 if (skb != NULL) { 494 const struct inet_request_sock *ireq = inet_rsk(req); 495 struct dccp_hdr *dh = dccp_hdr(skb); 496 497 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 498 ireq->ir_rmt_addr); 499 rcu_read_lock(); 500 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 501 ireq->ir_rmt_addr, 502 rcu_dereference(ireq->ireq_opt)); 503 rcu_read_unlock(); 504 err = net_xmit_eval(err); 505 } 506 507 out: 508 dst_release(dst); 509 return err; 510 } 511 512 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 513 { 514 int err; 515 const struct iphdr *rxiph; 516 struct sk_buff *skb; 517 struct dst_entry *dst; 518 struct net *net = dev_net(skb_dst(rxskb)->dev); 519 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 520 521 /* Never send a reset in response to a reset. */ 522 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 523 return; 524 525 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 526 return; 527 528 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 529 if (dst == NULL) 530 return; 531 532 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 533 if (skb == NULL) 534 goto out; 535 536 rxiph = ip_hdr(rxskb); 537 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 538 rxiph->daddr); 539 skb_dst_set(skb, dst_clone(dst)); 540 541 local_bh_disable(); 542 bh_lock_sock(ctl_sk); 543 err = ip_build_and_send_pkt(skb, ctl_sk, 544 rxiph->daddr, rxiph->saddr, NULL); 545 bh_unlock_sock(ctl_sk); 546 547 if (net_xmit_eval(err) == 0) { 548 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 549 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 550 } 551 local_bh_enable(); 552 out: 553 dst_release(dst); 554 } 555 556 static void dccp_v4_reqsk_destructor(struct request_sock *req) 557 { 558 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 559 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 560 } 561 562 void dccp_syn_ack_timeout(const struct request_sock *req) 563 { 564 } 565 EXPORT_SYMBOL(dccp_syn_ack_timeout); 566 567 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 568 .family = PF_INET, 569 .obj_size = sizeof(struct dccp_request_sock), 570 .rtx_syn_ack = dccp_v4_send_response, 571 .send_ack = dccp_reqsk_send_ack, 572 .destructor = dccp_v4_reqsk_destructor, 573 .send_reset = dccp_v4_ctl_send_reset, 574 .syn_ack_timeout = dccp_syn_ack_timeout, 575 }; 576 577 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 578 { 579 struct inet_request_sock *ireq; 580 struct request_sock *req; 581 struct dccp_request_sock *dreq; 582 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 583 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 584 585 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 586 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 587 return 0; /* discard, don't send a reset here */ 588 589 if (dccp_bad_service_code(sk, service)) { 590 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 591 goto drop; 592 } 593 /* 594 * TW buckets are converted to open requests without 595 * limitations, they conserve resources and peer is 596 * evidently real one. 597 */ 598 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 599 if (inet_csk_reqsk_queue_is_full(sk)) 600 goto drop; 601 602 if (sk_acceptq_is_full(sk)) 603 goto drop; 604 605 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 606 if (req == NULL) 607 goto drop; 608 609 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 610 goto drop_and_free; 611 612 dreq = dccp_rsk(req); 613 if (dccp_parse_options(sk, dreq, skb)) 614 goto drop_and_free; 615 616 if (security_inet_conn_request(sk, skb, req)) 617 goto drop_and_free; 618 619 ireq = inet_rsk(req); 620 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 621 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 622 ireq->ir_mark = inet_request_mark(sk, skb); 623 ireq->ireq_family = AF_INET; 624 ireq->ir_iif = sk->sk_bound_dev_if; 625 626 /* 627 * Step 3: Process LISTEN state 628 * 629 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 630 * 631 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 632 */ 633 dreq->dreq_isr = dcb->dccpd_seq; 634 dreq->dreq_gsr = dreq->dreq_isr; 635 dreq->dreq_iss = dccp_v4_init_sequence(skb); 636 dreq->dreq_gss = dreq->dreq_iss; 637 dreq->dreq_service = service; 638 639 if (dccp_v4_send_response(sk, req)) 640 goto drop_and_free; 641 642 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 643 reqsk_put(req); 644 return 0; 645 646 drop_and_free: 647 reqsk_free(req); 648 drop: 649 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 650 return -1; 651 } 652 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 653 654 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 655 { 656 struct dccp_hdr *dh = dccp_hdr(skb); 657 658 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 659 if (dccp_rcv_established(sk, skb, dh, skb->len)) 660 goto reset; 661 return 0; 662 } 663 664 /* 665 * Step 3: Process LISTEN state 666 * If P.type == Request or P contains a valid Init Cookie option, 667 * (* Must scan the packet's options to check for Init 668 * Cookies. Only Init Cookies are processed here, 669 * however; other options are processed in Step 8. This 670 * scan need only be performed if the endpoint uses Init 671 * Cookies *) 672 * (* Generate a new socket and switch to that socket *) 673 * Set S := new socket for this port pair 674 * S.state = RESPOND 675 * Choose S.ISS (initial seqno) or set from Init Cookies 676 * Initialize S.GAR := S.ISS 677 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 678 * Continue with S.state == RESPOND 679 * (* A Response packet will be generated in Step 11 *) 680 * Otherwise, 681 * Generate Reset(No Connection) unless P.type == Reset 682 * Drop packet and return 683 * 684 * NOTE: the check for the packet types is done in 685 * dccp_rcv_state_process 686 */ 687 688 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 689 goto reset; 690 return 0; 691 692 reset: 693 dccp_v4_ctl_send_reset(sk, skb); 694 kfree_skb(skb); 695 return 0; 696 } 697 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 698 699 /** 700 * dccp_invalid_packet - check for malformed packets 701 * Implements RFC 4340, 8.5: Step 1: Check header basics 702 * Packets that fail these checks are ignored and do not receive Resets. 703 */ 704 int dccp_invalid_packet(struct sk_buff *skb) 705 { 706 const struct dccp_hdr *dh; 707 unsigned int cscov; 708 u8 dccph_doff; 709 710 if (skb->pkt_type != PACKET_HOST) 711 return 1; 712 713 /* If the packet is shorter than 12 bytes, drop packet and return */ 714 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 715 DCCP_WARN("pskb_may_pull failed\n"); 716 return 1; 717 } 718 719 dh = dccp_hdr(skb); 720 721 /* If P.type is not understood, drop packet and return */ 722 if (dh->dccph_type >= DCCP_PKT_INVALID) { 723 DCCP_WARN("invalid packet type\n"); 724 return 1; 725 } 726 727 /* 728 * If P.Data Offset is too small for packet type, drop packet and return 729 */ 730 dccph_doff = dh->dccph_doff; 731 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 732 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 733 return 1; 734 } 735 /* 736 * If P.Data Offset is too too large for packet, drop packet and return 737 */ 738 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 739 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 740 return 1; 741 } 742 dh = dccp_hdr(skb); 743 /* 744 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 745 * has short sequence numbers), drop packet and return 746 */ 747 if ((dh->dccph_type < DCCP_PKT_DATA || 748 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 749 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 750 dccp_packet_name(dh->dccph_type)); 751 return 1; 752 } 753 754 /* 755 * If P.CsCov is too large for the packet size, drop packet and return. 756 * This must come _before_ checksumming (not as RFC 4340 suggests). 757 */ 758 cscov = dccp_csum_coverage(skb); 759 if (cscov > skb->len) { 760 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 761 dh->dccph_cscov, skb->len); 762 return 1; 763 } 764 765 /* If header checksum is incorrect, drop packet and return. 766 * (This step is completed in the AF-dependent functions.) */ 767 skb->csum = skb_checksum(skb, 0, cscov, 0); 768 769 return 0; 770 } 771 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 772 773 /* this is called when real data arrives */ 774 static int dccp_v4_rcv(struct sk_buff *skb) 775 { 776 const struct dccp_hdr *dh; 777 const struct iphdr *iph; 778 bool refcounted; 779 struct sock *sk; 780 int min_cov; 781 782 /* Step 1: Check header basics */ 783 784 if (dccp_invalid_packet(skb)) 785 goto discard_it; 786 787 iph = ip_hdr(skb); 788 /* Step 1: If header checksum is incorrect, drop packet and return */ 789 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 790 DCCP_WARN("dropped packet with invalid checksum\n"); 791 goto discard_it; 792 } 793 794 dh = dccp_hdr(skb); 795 796 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 797 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 798 799 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 800 dccp_packet_name(dh->dccph_type), 801 &iph->saddr, ntohs(dh->dccph_sport), 802 &iph->daddr, ntohs(dh->dccph_dport), 803 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 804 805 if (dccp_packet_without_ack(skb)) { 806 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 807 dccp_pr_debug_cat("\n"); 808 } else { 809 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 810 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 811 DCCP_SKB_CB(skb)->dccpd_ack_seq); 812 } 813 814 lookup: 815 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 816 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 817 if (!sk) { 818 dccp_pr_debug("failed to look up flow ID in table and " 819 "get corresponding socket\n"); 820 goto no_dccp_socket; 821 } 822 823 /* 824 * Step 2: 825 * ... or S.state == TIMEWAIT, 826 * Generate Reset(No Connection) unless P.type == Reset 827 * Drop packet and return 828 */ 829 if (sk->sk_state == DCCP_TIME_WAIT) { 830 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 831 inet_twsk_put(inet_twsk(sk)); 832 goto no_dccp_socket; 833 } 834 835 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 836 struct request_sock *req = inet_reqsk(sk); 837 struct sock *nsk; 838 839 sk = req->rsk_listener; 840 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 841 inet_csk_reqsk_queue_drop_and_put(sk, req); 842 goto lookup; 843 } 844 sock_hold(sk); 845 refcounted = true; 846 nsk = dccp_check_req(sk, skb, req); 847 if (!nsk) { 848 reqsk_put(req); 849 goto discard_and_relse; 850 } 851 if (nsk == sk) { 852 reqsk_put(req); 853 } else if (dccp_child_process(sk, nsk, skb)) { 854 dccp_v4_ctl_send_reset(sk, skb); 855 goto discard_and_relse; 856 } else { 857 sock_put(sk); 858 return 0; 859 } 860 } 861 /* 862 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 863 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 864 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 865 */ 866 min_cov = dccp_sk(sk)->dccps_pcrlen; 867 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 868 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 869 dh->dccph_cscov, min_cov); 870 /* FIXME: "Such packets SHOULD be reported using Data Dropped 871 * options (Section 11.7) with Drop Code 0, Protocol 872 * Constraints." */ 873 goto discard_and_relse; 874 } 875 876 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 877 goto discard_and_relse; 878 nf_reset(skb); 879 880 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 881 882 no_dccp_socket: 883 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 884 goto discard_it; 885 /* 886 * Step 2: 887 * If no socket ... 888 * Generate Reset(No Connection) unless P.type == Reset 889 * Drop packet and return 890 */ 891 if (dh->dccph_type != DCCP_PKT_RESET) { 892 DCCP_SKB_CB(skb)->dccpd_reset_code = 893 DCCP_RESET_CODE_NO_CONNECTION; 894 dccp_v4_ctl_send_reset(sk, skb); 895 } 896 897 discard_it: 898 kfree_skb(skb); 899 return 0; 900 901 discard_and_relse: 902 if (refcounted) 903 sock_put(sk); 904 goto discard_it; 905 } 906 907 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 908 .queue_xmit = ip_queue_xmit, 909 .send_check = dccp_v4_send_check, 910 .rebuild_header = inet_sk_rebuild_header, 911 .conn_request = dccp_v4_conn_request, 912 .syn_recv_sock = dccp_v4_request_recv_sock, 913 .net_header_len = sizeof(struct iphdr), 914 .setsockopt = ip_setsockopt, 915 .getsockopt = ip_getsockopt, 916 .addr2sockaddr = inet_csk_addr2sockaddr, 917 .sockaddr_len = sizeof(struct sockaddr_in), 918 #ifdef CONFIG_COMPAT 919 .compat_setsockopt = compat_ip_setsockopt, 920 .compat_getsockopt = compat_ip_getsockopt, 921 #endif 922 }; 923 924 static int dccp_v4_init_sock(struct sock *sk) 925 { 926 static __u8 dccp_v4_ctl_sock_initialized; 927 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 928 929 if (err == 0) { 930 if (unlikely(!dccp_v4_ctl_sock_initialized)) 931 dccp_v4_ctl_sock_initialized = 1; 932 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 933 } 934 935 return err; 936 } 937 938 static struct timewait_sock_ops dccp_timewait_sock_ops = { 939 .twsk_obj_size = sizeof(struct inet_timewait_sock), 940 }; 941 942 static struct proto dccp_v4_prot = { 943 .name = "DCCP", 944 .owner = THIS_MODULE, 945 .close = dccp_close, 946 .connect = dccp_v4_connect, 947 .disconnect = dccp_disconnect, 948 .ioctl = dccp_ioctl, 949 .init = dccp_v4_init_sock, 950 .setsockopt = dccp_setsockopt, 951 .getsockopt = dccp_getsockopt, 952 .sendmsg = dccp_sendmsg, 953 .recvmsg = dccp_recvmsg, 954 .backlog_rcv = dccp_v4_do_rcv, 955 .hash = inet_hash, 956 .unhash = inet_unhash, 957 .accept = inet_csk_accept, 958 .get_port = inet_csk_get_port, 959 .shutdown = dccp_shutdown, 960 .destroy = dccp_destroy_sock, 961 .orphan_count = &dccp_orphan_count, 962 .max_header = MAX_DCCP_HEADER, 963 .obj_size = sizeof(struct dccp_sock), 964 .slab_flags = SLAB_TYPESAFE_BY_RCU, 965 .rsk_prot = &dccp_request_sock_ops, 966 .twsk_prot = &dccp_timewait_sock_ops, 967 .h.hashinfo = &dccp_hashinfo, 968 #ifdef CONFIG_COMPAT 969 .compat_setsockopt = compat_dccp_setsockopt, 970 .compat_getsockopt = compat_dccp_getsockopt, 971 #endif 972 }; 973 974 static const struct net_protocol dccp_v4_protocol = { 975 .handler = dccp_v4_rcv, 976 .err_handler = dccp_v4_err, 977 .no_policy = 1, 978 .netns_ok = 1, 979 .icmp_strict_tag_validation = 1, 980 }; 981 982 static const struct proto_ops inet_dccp_ops = { 983 .family = PF_INET, 984 .owner = THIS_MODULE, 985 .release = inet_release, 986 .bind = inet_bind, 987 .connect = inet_stream_connect, 988 .socketpair = sock_no_socketpair, 989 .accept = inet_accept, 990 .getname = inet_getname, 991 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 992 .poll = dccp_poll, 993 .ioctl = inet_ioctl, 994 .gettstamp = sock_gettstamp, 995 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 996 .listen = inet_dccp_listen, 997 .shutdown = inet_shutdown, 998 .setsockopt = sock_common_setsockopt, 999 .getsockopt = sock_common_getsockopt, 1000 .sendmsg = inet_sendmsg, 1001 .recvmsg = sock_common_recvmsg, 1002 .mmap = sock_no_mmap, 1003 .sendpage = sock_no_sendpage, 1004 #ifdef CONFIG_COMPAT 1005 .compat_setsockopt = compat_sock_common_setsockopt, 1006 .compat_getsockopt = compat_sock_common_getsockopt, 1007 #endif 1008 }; 1009 1010 static struct inet_protosw dccp_v4_protosw = { 1011 .type = SOCK_DCCP, 1012 .protocol = IPPROTO_DCCP, 1013 .prot = &dccp_v4_prot, 1014 .ops = &inet_dccp_ops, 1015 .flags = INET_PROTOSW_ICSK, 1016 }; 1017 1018 static int __net_init dccp_v4_init_net(struct net *net) 1019 { 1020 if (dccp_hashinfo.bhash == NULL) 1021 return -ESOCKTNOSUPPORT; 1022 1023 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1024 SOCK_DCCP, IPPROTO_DCCP, net); 1025 } 1026 1027 static void __net_exit dccp_v4_exit_net(struct net *net) 1028 { 1029 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1030 } 1031 1032 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1033 { 1034 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1035 } 1036 1037 static struct pernet_operations dccp_v4_ops = { 1038 .init = dccp_v4_init_net, 1039 .exit = dccp_v4_exit_net, 1040 .exit_batch = dccp_v4_exit_batch, 1041 }; 1042 1043 static int __init dccp_v4_init(void) 1044 { 1045 int err = proto_register(&dccp_v4_prot, 1); 1046 1047 if (err) 1048 goto out; 1049 1050 inet_register_protosw(&dccp_v4_protosw); 1051 1052 err = register_pernet_subsys(&dccp_v4_ops); 1053 if (err) 1054 goto out_destroy_ctl_sock; 1055 1056 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1057 if (err) 1058 goto out_proto_unregister; 1059 1060 out: 1061 return err; 1062 out_proto_unregister: 1063 unregister_pernet_subsys(&dccp_v4_ops); 1064 out_destroy_ctl_sock: 1065 inet_unregister_protosw(&dccp_v4_protosw); 1066 proto_unregister(&dccp_v4_prot); 1067 goto out; 1068 } 1069 1070 static void __exit dccp_v4_exit(void) 1071 { 1072 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1073 unregister_pernet_subsys(&dccp_v4_ops); 1074 inet_unregister_protosw(&dccp_v4_protosw); 1075 proto_unregister(&dccp_v4_prot); 1076 } 1077 1078 module_init(dccp_v4_init); 1079 module_exit(dccp_v4_exit); 1080 1081 /* 1082 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1083 * values directly, Also cover the case where the protocol is not specified, 1084 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1085 */ 1086 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1087 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1088 MODULE_LICENSE("GPL"); 1089 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1090 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1091