1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/dccp/ipv4.c 4 * 5 * An implementation of the DCCP protocol 6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7 */ 8 9 #include <linux/dccp.h> 10 #include <linux/icmp.h> 11 #include <linux/slab.h> 12 #include <linux/module.h> 13 #include <linux/skbuff.h> 14 #include <linux/random.h> 15 16 #include <net/icmp.h> 17 #include <net/inet_common.h> 18 #include <net/inet_hashtables.h> 19 #include <net/inet_sock.h> 20 #include <net/protocol.h> 21 #include <net/sock.h> 22 #include <net/timewait_sock.h> 23 #include <net/tcp_states.h> 24 #include <net/xfrm.h> 25 #include <net/secure_seq.h> 26 27 #include "ackvec.h" 28 #include "ccid.h" 29 #include "dccp.h" 30 #include "feat.h" 31 32 /* 33 * The per-net dccp.v4_ctl_sk socket is used for responding to 34 * the Out-of-the-blue (OOTB) packets. A control sock will be created 35 * for this socket at the initialization time. 36 */ 37 38 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 39 { 40 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 41 struct inet_sock *inet = inet_sk(sk); 42 struct dccp_sock *dp = dccp_sk(sk); 43 __be16 orig_sport, orig_dport; 44 __be32 daddr, nexthop; 45 struct flowi4 *fl4; 46 struct rtable *rt; 47 int err; 48 struct ip_options_rcu *inet_opt; 49 50 dp->dccps_role = DCCP_ROLE_CLIENT; 51 52 if (addr_len < sizeof(struct sockaddr_in)) 53 return -EINVAL; 54 55 if (usin->sin_family != AF_INET) 56 return -EAFNOSUPPORT; 57 58 nexthop = daddr = usin->sin_addr.s_addr; 59 60 inet_opt = rcu_dereference_protected(inet->inet_opt, 61 lockdep_sock_is_held(sk)); 62 if (inet_opt != NULL && inet_opt->opt.srr) { 63 if (daddr == 0) 64 return -EINVAL; 65 nexthop = inet_opt->opt.faddr; 66 } 67 68 orig_sport = inet->inet_sport; 69 orig_dport = usin->sin_port; 70 fl4 = &inet->cork.fl.u.ip4; 71 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 72 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 73 IPPROTO_DCCP, 74 orig_sport, orig_dport, sk); 75 if (IS_ERR(rt)) 76 return PTR_ERR(rt); 77 78 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 79 ip_rt_put(rt); 80 return -ENETUNREACH; 81 } 82 83 if (inet_opt == NULL || !inet_opt->opt.srr) 84 daddr = fl4->daddr; 85 86 if (inet->inet_saddr == 0) 87 inet->inet_saddr = fl4->saddr; 88 sk_rcv_saddr_set(sk, inet->inet_saddr); 89 inet->inet_dport = usin->sin_port; 90 sk_daddr_set(sk, daddr); 91 92 inet_csk(sk)->icsk_ext_hdr_len = 0; 93 if (inet_opt) 94 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 95 /* 96 * Socket identity is still unknown (sport may be zero). 97 * However we set state to DCCP_REQUESTING and not releasing socket 98 * lock select source port, enter ourselves into the hash tables and 99 * complete initialization after this. 100 */ 101 dccp_set_state(sk, DCCP_REQUESTING); 102 err = inet_hash_connect(&dccp_death_row, sk); 103 if (err != 0) 104 goto failure; 105 106 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 107 inet->inet_sport, inet->inet_dport, sk); 108 if (IS_ERR(rt)) { 109 err = PTR_ERR(rt); 110 rt = NULL; 111 goto failure; 112 } 113 /* OK, now commit destination to socket. */ 114 sk_setup_caps(sk, &rt->dst); 115 116 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 117 inet->inet_daddr, 118 inet->inet_sport, 119 inet->inet_dport); 120 inet->inet_id = prandom_u32(); 121 122 err = dccp_connect(sk); 123 rt = NULL; 124 if (err != 0) 125 goto failure; 126 out: 127 return err; 128 failure: 129 /* 130 * This unhashes the socket and releases the local port, if necessary. 131 */ 132 dccp_set_state(sk, DCCP_CLOSED); 133 ip_rt_put(rt); 134 sk->sk_route_caps = 0; 135 inet->inet_dport = 0; 136 goto out; 137 } 138 EXPORT_SYMBOL_GPL(dccp_v4_connect); 139 140 /* 141 * This routine does path mtu discovery as defined in RFC1191. 142 */ 143 static inline void dccp_do_pmtu_discovery(struct sock *sk, 144 const struct iphdr *iph, 145 u32 mtu) 146 { 147 struct dst_entry *dst; 148 const struct inet_sock *inet = inet_sk(sk); 149 const struct dccp_sock *dp = dccp_sk(sk); 150 151 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 152 * send out by Linux are always < 576bytes so they should go through 153 * unfragmented). 154 */ 155 if (sk->sk_state == DCCP_LISTEN) 156 return; 157 158 dst = inet_csk_update_pmtu(sk, mtu); 159 if (!dst) 160 return; 161 162 /* Something is about to be wrong... Remember soft error 163 * for the case, if this connection will not able to recover. 164 */ 165 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 166 sk->sk_err_soft = EMSGSIZE; 167 168 mtu = dst_mtu(dst); 169 170 if (inet->pmtudisc != IP_PMTUDISC_DONT && 171 ip_sk_accept_pmtu(sk) && 172 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 173 dccp_sync_mss(sk, mtu); 174 175 /* 176 * From RFC 4340, sec. 14.1: 177 * 178 * DCCP-Sync packets are the best choice for upward 179 * probing, since DCCP-Sync probes do not risk application 180 * data loss. 181 */ 182 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 183 } /* else let the usual retransmit timer handle it */ 184 } 185 186 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 187 { 188 struct dst_entry *dst = __sk_dst_check(sk, 0); 189 190 if (dst) 191 dst->ops->redirect(dst, sk, skb); 192 } 193 194 void dccp_req_err(struct sock *sk, u64 seq) 195 { 196 struct request_sock *req = inet_reqsk(sk); 197 struct net *net = sock_net(sk); 198 199 /* 200 * ICMPs are not backlogged, hence we cannot get an established 201 * socket here. 202 */ 203 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 204 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 205 } else { 206 /* 207 * Still in RESPOND, just remove it silently. 208 * There is no good way to pass the error to the newly 209 * created socket, and POSIX does not want network 210 * errors returned from accept(). 211 */ 212 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 213 } 214 reqsk_put(req); 215 } 216 EXPORT_SYMBOL(dccp_req_err); 217 218 /* 219 * This routine is called by the ICMP module when it gets some sort of error 220 * condition. If err < 0 then the socket should be closed and the error 221 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 222 * After adjustment header points to the first 8 bytes of the tcp header. We 223 * need to find the appropriate port. 224 * 225 * The locking strategy used here is very "optimistic". When someone else 226 * accesses the socket the ICMP is just dropped and for some paths there is no 227 * check at all. A more general error queue to queue errors for later handling 228 * is probably better. 229 */ 230 static int dccp_v4_err(struct sk_buff *skb, u32 info) 231 { 232 const struct iphdr *iph = (struct iphdr *)skb->data; 233 const u8 offset = iph->ihl << 2; 234 const struct dccp_hdr *dh; 235 struct dccp_sock *dp; 236 struct inet_sock *inet; 237 const int type = icmp_hdr(skb)->type; 238 const int code = icmp_hdr(skb)->code; 239 struct sock *sk; 240 __u64 seq; 241 int err; 242 struct net *net = dev_net(skb->dev); 243 244 /* Only need dccph_dport & dccph_sport which are the first 245 * 4 bytes in dccp header. 246 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 247 */ 248 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 249 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 250 dh = (struct dccp_hdr *)(skb->data + offset); 251 252 sk = __inet_lookup_established(net, &dccp_hashinfo, 253 iph->daddr, dh->dccph_dport, 254 iph->saddr, ntohs(dh->dccph_sport), 255 inet_iif(skb), 0); 256 if (!sk) { 257 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 258 return -ENOENT; 259 } 260 261 if (sk->sk_state == DCCP_TIME_WAIT) { 262 inet_twsk_put(inet_twsk(sk)); 263 return 0; 264 } 265 seq = dccp_hdr_seq(dh); 266 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 267 dccp_req_err(sk, seq); 268 return 0; 269 } 270 271 bh_lock_sock(sk); 272 /* If too many ICMPs get dropped on busy 273 * servers this needs to be solved differently. 274 */ 275 if (sock_owned_by_user(sk)) 276 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 277 278 if (sk->sk_state == DCCP_CLOSED) 279 goto out; 280 281 dp = dccp_sk(sk); 282 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 283 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 284 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 285 goto out; 286 } 287 288 switch (type) { 289 case ICMP_REDIRECT: 290 if (!sock_owned_by_user(sk)) 291 dccp_do_redirect(skb, sk); 292 goto out; 293 case ICMP_SOURCE_QUENCH: 294 /* Just silently ignore these. */ 295 goto out; 296 case ICMP_PARAMETERPROB: 297 err = EPROTO; 298 break; 299 case ICMP_DEST_UNREACH: 300 if (code > NR_ICMP_UNREACH) 301 goto out; 302 303 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 304 if (!sock_owned_by_user(sk)) 305 dccp_do_pmtu_discovery(sk, iph, info); 306 goto out; 307 } 308 309 err = icmp_err_convert[code].errno; 310 break; 311 case ICMP_TIME_EXCEEDED: 312 err = EHOSTUNREACH; 313 break; 314 default: 315 goto out; 316 } 317 318 switch (sk->sk_state) { 319 case DCCP_REQUESTING: 320 case DCCP_RESPOND: 321 if (!sock_owned_by_user(sk)) { 322 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 323 sk->sk_err = err; 324 325 sk->sk_error_report(sk); 326 327 dccp_done(sk); 328 } else 329 sk->sk_err_soft = err; 330 goto out; 331 } 332 333 /* If we've already connected we will keep trying 334 * until we time out, or the user gives up. 335 * 336 * rfc1122 4.2.3.9 allows to consider as hard errors 337 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 338 * but it is obsoleted by pmtu discovery). 339 * 340 * Note, that in modern internet, where routing is unreliable 341 * and in each dark corner broken firewalls sit, sending random 342 * errors ordered by their masters even this two messages finally lose 343 * their original sense (even Linux sends invalid PORT_UNREACHs) 344 * 345 * Now we are in compliance with RFCs. 346 * --ANK (980905) 347 */ 348 349 inet = inet_sk(sk); 350 if (!sock_owned_by_user(sk) && inet->recverr) { 351 sk->sk_err = err; 352 sk->sk_error_report(sk); 353 } else /* Only an error on timeout */ 354 sk->sk_err_soft = err; 355 out: 356 bh_unlock_sock(sk); 357 sock_put(sk); 358 return 0; 359 } 360 361 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 362 __be32 src, __be32 dst) 363 { 364 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 365 } 366 367 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 368 { 369 const struct inet_sock *inet = inet_sk(sk); 370 struct dccp_hdr *dh = dccp_hdr(skb); 371 372 dccp_csum_outgoing(skb); 373 dh->dccph_checksum = dccp_v4_csum_finish(skb, 374 inet->inet_saddr, 375 inet->inet_daddr); 376 } 377 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 378 379 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 380 { 381 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 382 ip_hdr(skb)->saddr, 383 dccp_hdr(skb)->dccph_dport, 384 dccp_hdr(skb)->dccph_sport); 385 } 386 387 /* 388 * The three way handshake has completed - we got a valid ACK or DATAACK - 389 * now create the new socket. 390 * 391 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 392 */ 393 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 394 struct sk_buff *skb, 395 struct request_sock *req, 396 struct dst_entry *dst, 397 struct request_sock *req_unhash, 398 bool *own_req) 399 { 400 struct inet_request_sock *ireq; 401 struct inet_sock *newinet; 402 struct sock *newsk; 403 404 if (sk_acceptq_is_full(sk)) 405 goto exit_overflow; 406 407 newsk = dccp_create_openreq_child(sk, req, skb); 408 if (newsk == NULL) 409 goto exit_nonewsk; 410 411 newinet = inet_sk(newsk); 412 ireq = inet_rsk(req); 413 sk_daddr_set(newsk, ireq->ir_rmt_addr); 414 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 415 newinet->inet_saddr = ireq->ir_loc_addr; 416 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 417 newinet->mc_index = inet_iif(skb); 418 newinet->mc_ttl = ip_hdr(skb)->ttl; 419 newinet->inet_id = prandom_u32(); 420 421 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 422 goto put_and_exit; 423 424 sk_setup_caps(newsk, dst); 425 426 dccp_sync_mss(newsk, dst_mtu(dst)); 427 428 if (__inet_inherit_port(sk, newsk) < 0) 429 goto put_and_exit; 430 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 431 if (*own_req) 432 ireq->ireq_opt = NULL; 433 else 434 newinet->inet_opt = NULL; 435 return newsk; 436 437 exit_overflow: 438 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 439 exit_nonewsk: 440 dst_release(dst); 441 exit: 442 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 443 return NULL; 444 put_and_exit: 445 newinet->inet_opt = NULL; 446 inet_csk_prepare_forced_close(newsk); 447 dccp_done(newsk); 448 goto exit; 449 } 450 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 451 452 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 453 struct sk_buff *skb) 454 { 455 struct rtable *rt; 456 const struct iphdr *iph = ip_hdr(skb); 457 struct flowi4 fl4 = { 458 .flowi4_oif = inet_iif(skb), 459 .daddr = iph->saddr, 460 .saddr = iph->daddr, 461 .flowi4_tos = RT_CONN_FLAGS(sk), 462 .flowi4_proto = sk->sk_protocol, 463 .fl4_sport = dccp_hdr(skb)->dccph_dport, 464 .fl4_dport = dccp_hdr(skb)->dccph_sport, 465 }; 466 467 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 468 rt = ip_route_output_flow(net, &fl4, sk); 469 if (IS_ERR(rt)) { 470 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 471 return NULL; 472 } 473 474 return &rt->dst; 475 } 476 477 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 478 { 479 int err = -1; 480 struct sk_buff *skb; 481 struct dst_entry *dst; 482 struct flowi4 fl4; 483 484 dst = inet_csk_route_req(sk, &fl4, req); 485 if (dst == NULL) 486 goto out; 487 488 skb = dccp_make_response(sk, dst, req); 489 if (skb != NULL) { 490 const struct inet_request_sock *ireq = inet_rsk(req); 491 struct dccp_hdr *dh = dccp_hdr(skb); 492 493 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 494 ireq->ir_rmt_addr); 495 rcu_read_lock(); 496 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 497 ireq->ir_rmt_addr, 498 rcu_dereference(ireq->ireq_opt), 499 inet_sk(sk)->tos); 500 rcu_read_unlock(); 501 err = net_xmit_eval(err); 502 } 503 504 out: 505 dst_release(dst); 506 return err; 507 } 508 509 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 510 { 511 int err; 512 const struct iphdr *rxiph; 513 struct sk_buff *skb; 514 struct dst_entry *dst; 515 struct net *net = dev_net(skb_dst(rxskb)->dev); 516 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 517 518 /* Never send a reset in response to a reset. */ 519 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 520 return; 521 522 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 523 return; 524 525 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 526 if (dst == NULL) 527 return; 528 529 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 530 if (skb == NULL) 531 goto out; 532 533 rxiph = ip_hdr(rxskb); 534 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 535 rxiph->daddr); 536 skb_dst_set(skb, dst_clone(dst)); 537 538 local_bh_disable(); 539 bh_lock_sock(ctl_sk); 540 err = ip_build_and_send_pkt(skb, ctl_sk, 541 rxiph->daddr, rxiph->saddr, NULL, 542 inet_sk(ctl_sk)->tos); 543 bh_unlock_sock(ctl_sk); 544 545 if (net_xmit_eval(err) == 0) { 546 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 547 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 548 } 549 local_bh_enable(); 550 out: 551 dst_release(dst); 552 } 553 554 static void dccp_v4_reqsk_destructor(struct request_sock *req) 555 { 556 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 557 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 558 } 559 560 void dccp_syn_ack_timeout(const struct request_sock *req) 561 { 562 } 563 EXPORT_SYMBOL(dccp_syn_ack_timeout); 564 565 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 566 .family = PF_INET, 567 .obj_size = sizeof(struct dccp_request_sock), 568 .rtx_syn_ack = dccp_v4_send_response, 569 .send_ack = dccp_reqsk_send_ack, 570 .destructor = dccp_v4_reqsk_destructor, 571 .send_reset = dccp_v4_ctl_send_reset, 572 .syn_ack_timeout = dccp_syn_ack_timeout, 573 }; 574 575 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 576 { 577 struct inet_request_sock *ireq; 578 struct request_sock *req; 579 struct dccp_request_sock *dreq; 580 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 581 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 582 583 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 584 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 585 return 0; /* discard, don't send a reset here */ 586 587 if (dccp_bad_service_code(sk, service)) { 588 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 589 goto drop; 590 } 591 /* 592 * TW buckets are converted to open requests without 593 * limitations, they conserve resources and peer is 594 * evidently real one. 595 */ 596 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 597 if (inet_csk_reqsk_queue_is_full(sk)) 598 goto drop; 599 600 if (sk_acceptq_is_full(sk)) 601 goto drop; 602 603 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 604 if (req == NULL) 605 goto drop; 606 607 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 608 goto drop_and_free; 609 610 dreq = dccp_rsk(req); 611 if (dccp_parse_options(sk, dreq, skb)) 612 goto drop_and_free; 613 614 if (security_inet_conn_request(sk, skb, req)) 615 goto drop_and_free; 616 617 ireq = inet_rsk(req); 618 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 619 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 620 ireq->ir_mark = inet_request_mark(sk, skb); 621 ireq->ireq_family = AF_INET; 622 ireq->ir_iif = sk->sk_bound_dev_if; 623 624 /* 625 * Step 3: Process LISTEN state 626 * 627 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 628 * 629 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 630 */ 631 dreq->dreq_isr = dcb->dccpd_seq; 632 dreq->dreq_gsr = dreq->dreq_isr; 633 dreq->dreq_iss = dccp_v4_init_sequence(skb); 634 dreq->dreq_gss = dreq->dreq_iss; 635 dreq->dreq_service = service; 636 637 if (dccp_v4_send_response(sk, req)) 638 goto drop_and_free; 639 640 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 641 reqsk_put(req); 642 return 0; 643 644 drop_and_free: 645 reqsk_free(req); 646 drop: 647 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 648 return -1; 649 } 650 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 651 652 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 653 { 654 struct dccp_hdr *dh = dccp_hdr(skb); 655 656 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 657 if (dccp_rcv_established(sk, skb, dh, skb->len)) 658 goto reset; 659 return 0; 660 } 661 662 /* 663 * Step 3: Process LISTEN state 664 * If P.type == Request or P contains a valid Init Cookie option, 665 * (* Must scan the packet's options to check for Init 666 * Cookies. Only Init Cookies are processed here, 667 * however; other options are processed in Step 8. This 668 * scan need only be performed if the endpoint uses Init 669 * Cookies *) 670 * (* Generate a new socket and switch to that socket *) 671 * Set S := new socket for this port pair 672 * S.state = RESPOND 673 * Choose S.ISS (initial seqno) or set from Init Cookies 674 * Initialize S.GAR := S.ISS 675 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 676 * Continue with S.state == RESPOND 677 * (* A Response packet will be generated in Step 11 *) 678 * Otherwise, 679 * Generate Reset(No Connection) unless P.type == Reset 680 * Drop packet and return 681 * 682 * NOTE: the check for the packet types is done in 683 * dccp_rcv_state_process 684 */ 685 686 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 687 goto reset; 688 return 0; 689 690 reset: 691 dccp_v4_ctl_send_reset(sk, skb); 692 kfree_skb(skb); 693 return 0; 694 } 695 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 696 697 /** 698 * dccp_invalid_packet - check for malformed packets 699 * @skb: Packet to validate 700 * 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 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_ct(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 }; 919 920 static int dccp_v4_init_sock(struct sock *sk) 921 { 922 static __u8 dccp_v4_ctl_sock_initialized; 923 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 924 925 if (err == 0) { 926 if (unlikely(!dccp_v4_ctl_sock_initialized)) 927 dccp_v4_ctl_sock_initialized = 1; 928 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 929 } 930 931 return err; 932 } 933 934 static struct timewait_sock_ops dccp_timewait_sock_ops = { 935 .twsk_obj_size = sizeof(struct inet_timewait_sock), 936 }; 937 938 static struct proto dccp_v4_prot = { 939 .name = "DCCP", 940 .owner = THIS_MODULE, 941 .close = dccp_close, 942 .connect = dccp_v4_connect, 943 .disconnect = dccp_disconnect, 944 .ioctl = dccp_ioctl, 945 .init = dccp_v4_init_sock, 946 .setsockopt = dccp_setsockopt, 947 .getsockopt = dccp_getsockopt, 948 .sendmsg = dccp_sendmsg, 949 .recvmsg = dccp_recvmsg, 950 .backlog_rcv = dccp_v4_do_rcv, 951 .hash = inet_hash, 952 .unhash = inet_unhash, 953 .accept = inet_csk_accept, 954 .get_port = inet_csk_get_port, 955 .shutdown = dccp_shutdown, 956 .destroy = dccp_destroy_sock, 957 .orphan_count = &dccp_orphan_count, 958 .max_header = MAX_DCCP_HEADER, 959 .obj_size = sizeof(struct dccp_sock), 960 .slab_flags = SLAB_TYPESAFE_BY_RCU, 961 .rsk_prot = &dccp_request_sock_ops, 962 .twsk_prot = &dccp_timewait_sock_ops, 963 .h.hashinfo = &dccp_hashinfo, 964 }; 965 966 static const struct net_protocol dccp_v4_protocol = { 967 .handler = dccp_v4_rcv, 968 .err_handler = dccp_v4_err, 969 .no_policy = 1, 970 .netns_ok = 1, 971 .icmp_strict_tag_validation = 1, 972 }; 973 974 static const struct proto_ops inet_dccp_ops = { 975 .family = PF_INET, 976 .owner = THIS_MODULE, 977 .release = inet_release, 978 .bind = inet_bind, 979 .connect = inet_stream_connect, 980 .socketpair = sock_no_socketpair, 981 .accept = inet_accept, 982 .getname = inet_getname, 983 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 984 .poll = dccp_poll, 985 .ioctl = inet_ioctl, 986 .gettstamp = sock_gettstamp, 987 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 988 .listen = inet_dccp_listen, 989 .shutdown = inet_shutdown, 990 .setsockopt = sock_common_setsockopt, 991 .getsockopt = sock_common_getsockopt, 992 .sendmsg = inet_sendmsg, 993 .recvmsg = sock_common_recvmsg, 994 .mmap = sock_no_mmap, 995 .sendpage = sock_no_sendpage, 996 }; 997 998 static struct inet_protosw dccp_v4_protosw = { 999 .type = SOCK_DCCP, 1000 .protocol = IPPROTO_DCCP, 1001 .prot = &dccp_v4_prot, 1002 .ops = &inet_dccp_ops, 1003 .flags = INET_PROTOSW_ICSK, 1004 }; 1005 1006 static int __net_init dccp_v4_init_net(struct net *net) 1007 { 1008 if (dccp_hashinfo.bhash == NULL) 1009 return -ESOCKTNOSUPPORT; 1010 1011 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1012 SOCK_DCCP, IPPROTO_DCCP, net); 1013 } 1014 1015 static void __net_exit dccp_v4_exit_net(struct net *net) 1016 { 1017 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1018 } 1019 1020 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1021 { 1022 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1023 } 1024 1025 static struct pernet_operations dccp_v4_ops = { 1026 .init = dccp_v4_init_net, 1027 .exit = dccp_v4_exit_net, 1028 .exit_batch = dccp_v4_exit_batch, 1029 }; 1030 1031 static int __init dccp_v4_init(void) 1032 { 1033 int err = proto_register(&dccp_v4_prot, 1); 1034 1035 if (err) 1036 goto out; 1037 1038 inet_register_protosw(&dccp_v4_protosw); 1039 1040 err = register_pernet_subsys(&dccp_v4_ops); 1041 if (err) 1042 goto out_destroy_ctl_sock; 1043 1044 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1045 if (err) 1046 goto out_proto_unregister; 1047 1048 out: 1049 return err; 1050 out_proto_unregister: 1051 unregister_pernet_subsys(&dccp_v4_ops); 1052 out_destroy_ctl_sock: 1053 inet_unregister_protosw(&dccp_v4_protosw); 1054 proto_unregister(&dccp_v4_prot); 1055 goto out; 1056 } 1057 1058 static void __exit dccp_v4_exit(void) 1059 { 1060 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1061 unregister_pernet_subsys(&dccp_v4_ops); 1062 inet_unregister_protosw(&dccp_v4_protosw); 1063 proto_unregister(&dccp_v4_prot); 1064 } 1065 1066 module_init(dccp_v4_init); 1067 module_exit(dccp_v4_exit); 1068 1069 /* 1070 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1071 * values directly, Also cover the case where the protocol is not specified, 1072 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1073 */ 1074 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1075 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1076 MODULE_LICENSE("GPL"); 1077 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1078 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1079