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 #include <net/netns/generic.h> 27 28 #include "ackvec.h" 29 #include "ccid.h" 30 #include "dccp.h" 31 #include "feat.h" 32 33 struct dccp_v4_pernet { 34 struct sock *v4_ctl_sk; 35 }; 36 37 static unsigned int dccp_v4_pernet_id __read_mostly; 38 39 /* 40 * The per-net v4_ctl_sk socket is used for responding to 41 * the Out-of-the-blue (OOTB) packets. A control sock will be created 42 * for this socket at the initialization time. 43 */ 44 45 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 46 { 47 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 48 struct inet_sock *inet = inet_sk(sk); 49 struct dccp_sock *dp = dccp_sk(sk); 50 __be16 orig_sport, orig_dport; 51 __be32 daddr, nexthop; 52 struct flowi4 *fl4; 53 struct rtable *rt; 54 int err; 55 struct ip_options_rcu *inet_opt; 56 57 dp->dccps_role = DCCP_ROLE_CLIENT; 58 59 if (addr_len < sizeof(struct sockaddr_in)) 60 return -EINVAL; 61 62 if (usin->sin_family != AF_INET) 63 return -EAFNOSUPPORT; 64 65 nexthop = daddr = usin->sin_addr.s_addr; 66 67 inet_opt = rcu_dereference_protected(inet->inet_opt, 68 lockdep_sock_is_held(sk)); 69 if (inet_opt != NULL && inet_opt->opt.srr) { 70 if (daddr == 0) 71 return -EINVAL; 72 nexthop = inet_opt->opt.faddr; 73 } 74 75 orig_sport = inet->inet_sport; 76 orig_dport = usin->sin_port; 77 fl4 = &inet->cork.fl.u.ip4; 78 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 79 sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport, 80 orig_dport, sk); 81 if (IS_ERR(rt)) 82 return PTR_ERR(rt); 83 84 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 85 ip_rt_put(rt); 86 return -ENETUNREACH; 87 } 88 89 if (inet_opt == NULL || !inet_opt->opt.srr) 90 daddr = fl4->daddr; 91 92 if (inet->inet_saddr == 0) 93 inet->inet_saddr = fl4->saddr; 94 sk_rcv_saddr_set(sk, inet->inet_saddr); 95 inet->inet_dport = usin->sin_port; 96 sk_daddr_set(sk, daddr); 97 98 inet_csk(sk)->icsk_ext_hdr_len = 0; 99 if (inet_opt) 100 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 101 /* 102 * Socket identity is still unknown (sport may be zero). 103 * However we set state to DCCP_REQUESTING and not releasing socket 104 * lock select source port, enter ourselves into the hash tables and 105 * complete initialization after this. 106 */ 107 dccp_set_state(sk, DCCP_REQUESTING); 108 err = inet_hash_connect(&dccp_death_row, sk); 109 if (err != 0) 110 goto failure; 111 112 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 113 inet->inet_sport, inet->inet_dport, sk); 114 if (IS_ERR(rt)) { 115 err = PTR_ERR(rt); 116 rt = NULL; 117 goto failure; 118 } 119 /* OK, now commit destination to socket. */ 120 sk_setup_caps(sk, &rt->dst); 121 122 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 123 inet->inet_daddr, 124 inet->inet_sport, 125 inet->inet_dport); 126 inet->inet_id = prandom_u32(); 127 128 err = dccp_connect(sk); 129 rt = NULL; 130 if (err != 0) 131 goto failure; 132 out: 133 return err; 134 failure: 135 /* 136 * This unhashes the socket and releases the local port, if necessary. 137 */ 138 dccp_set_state(sk, DCCP_CLOSED); 139 ip_rt_put(rt); 140 sk->sk_route_caps = 0; 141 inet->inet_dport = 0; 142 goto out; 143 } 144 EXPORT_SYMBOL_GPL(dccp_v4_connect); 145 146 /* 147 * This routine does path mtu discovery as defined in RFC1191. 148 */ 149 static inline void dccp_do_pmtu_discovery(struct sock *sk, 150 const struct iphdr *iph, 151 u32 mtu) 152 { 153 struct dst_entry *dst; 154 const struct inet_sock *inet = inet_sk(sk); 155 const struct dccp_sock *dp = dccp_sk(sk); 156 157 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 158 * send out by Linux are always < 576bytes so they should go through 159 * unfragmented). 160 */ 161 if (sk->sk_state == DCCP_LISTEN) 162 return; 163 164 dst = inet_csk_update_pmtu(sk, mtu); 165 if (!dst) 166 return; 167 168 /* Something is about to be wrong... Remember soft error 169 * for the case, if this connection will not able to recover. 170 */ 171 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 172 sk->sk_err_soft = EMSGSIZE; 173 174 mtu = dst_mtu(dst); 175 176 if (inet->pmtudisc != IP_PMTUDISC_DONT && 177 ip_sk_accept_pmtu(sk) && 178 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 179 dccp_sync_mss(sk, mtu); 180 181 /* 182 * From RFC 4340, sec. 14.1: 183 * 184 * DCCP-Sync packets are the best choice for upward 185 * probing, since DCCP-Sync probes do not risk application 186 * data loss. 187 */ 188 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 189 } /* else let the usual retransmit timer handle it */ 190 } 191 192 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 193 { 194 struct dst_entry *dst = __sk_dst_check(sk, 0); 195 196 if (dst) 197 dst->ops->redirect(dst, sk, skb); 198 } 199 200 void dccp_req_err(struct sock *sk, u64 seq) 201 { 202 struct request_sock *req = inet_reqsk(sk); 203 struct net *net = sock_net(sk); 204 205 /* 206 * ICMPs are not backlogged, hence we cannot get an established 207 * socket here. 208 */ 209 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 210 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 211 } else { 212 /* 213 * Still in RESPOND, just remove it silently. 214 * There is no good way to pass the error to the newly 215 * created socket, and POSIX does not want network 216 * errors returned from accept(). 217 */ 218 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 219 } 220 reqsk_put(req); 221 } 222 EXPORT_SYMBOL(dccp_req_err); 223 224 /* 225 * This routine is called by the ICMP module when it gets some sort of error 226 * condition. If err < 0 then the socket should be closed and the error 227 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 228 * After adjustment header points to the first 8 bytes of the tcp header. We 229 * need to find the appropriate port. 230 * 231 * The locking strategy used here is very "optimistic". When someone else 232 * accesses the socket the ICMP is just dropped and for some paths there is no 233 * check at all. A more general error queue to queue errors for later handling 234 * is probably better. 235 */ 236 static int dccp_v4_err(struct sk_buff *skb, u32 info) 237 { 238 const struct iphdr *iph = (struct iphdr *)skb->data; 239 const u8 offset = iph->ihl << 2; 240 const struct dccp_hdr *dh; 241 struct dccp_sock *dp; 242 struct inet_sock *inet; 243 const int type = icmp_hdr(skb)->type; 244 const int code = icmp_hdr(skb)->code; 245 struct sock *sk; 246 __u64 seq; 247 int err; 248 struct net *net = dev_net(skb->dev); 249 250 /* Only need dccph_dport & dccph_sport which are the first 251 * 4 bytes in dccp header. 252 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 253 */ 254 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 255 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 256 dh = (struct dccp_hdr *)(skb->data + offset); 257 258 sk = __inet_lookup_established(net, &dccp_hashinfo, 259 iph->daddr, dh->dccph_dport, 260 iph->saddr, ntohs(dh->dccph_sport), 261 inet_iif(skb), 0); 262 if (!sk) { 263 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 264 return -ENOENT; 265 } 266 267 if (sk->sk_state == DCCP_TIME_WAIT) { 268 inet_twsk_put(inet_twsk(sk)); 269 return 0; 270 } 271 seq = dccp_hdr_seq(dh); 272 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 273 dccp_req_err(sk, seq); 274 return 0; 275 } 276 277 bh_lock_sock(sk); 278 /* If too many ICMPs get dropped on busy 279 * servers this needs to be solved differently. 280 */ 281 if (sock_owned_by_user(sk)) 282 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 283 284 if (sk->sk_state == DCCP_CLOSED) 285 goto out; 286 287 dp = dccp_sk(sk); 288 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 289 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 290 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 291 goto out; 292 } 293 294 switch (type) { 295 case ICMP_REDIRECT: 296 if (!sock_owned_by_user(sk)) 297 dccp_do_redirect(skb, sk); 298 goto out; 299 case ICMP_SOURCE_QUENCH: 300 /* Just silently ignore these. */ 301 goto out; 302 case ICMP_PARAMETERPROB: 303 err = EPROTO; 304 break; 305 case ICMP_DEST_UNREACH: 306 if (code > NR_ICMP_UNREACH) 307 goto out; 308 309 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 310 if (!sock_owned_by_user(sk)) 311 dccp_do_pmtu_discovery(sk, iph, info); 312 goto out; 313 } 314 315 err = icmp_err_convert[code].errno; 316 break; 317 case ICMP_TIME_EXCEEDED: 318 err = EHOSTUNREACH; 319 break; 320 default: 321 goto out; 322 } 323 324 switch (sk->sk_state) { 325 case DCCP_REQUESTING: 326 case DCCP_RESPOND: 327 if (!sock_owned_by_user(sk)) { 328 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 329 sk->sk_err = err; 330 331 sk_error_report(sk); 332 333 dccp_done(sk); 334 } else 335 sk->sk_err_soft = err; 336 goto out; 337 } 338 339 /* If we've already connected we will keep trying 340 * until we time out, or the user gives up. 341 * 342 * rfc1122 4.2.3.9 allows to consider as hard errors 343 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 344 * but it is obsoleted by pmtu discovery). 345 * 346 * Note, that in modern internet, where routing is unreliable 347 * and in each dark corner broken firewalls sit, sending random 348 * errors ordered by their masters even this two messages finally lose 349 * their original sense (even Linux sends invalid PORT_UNREACHs) 350 * 351 * Now we are in compliance with RFCs. 352 * --ANK (980905) 353 */ 354 355 inet = inet_sk(sk); 356 if (!sock_owned_by_user(sk) && inet->recverr) { 357 sk->sk_err = err; 358 sk_error_report(sk); 359 } else /* Only an error on timeout */ 360 sk->sk_err_soft = err; 361 out: 362 bh_unlock_sock(sk); 363 sock_put(sk); 364 return 0; 365 } 366 367 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 368 __be32 src, __be32 dst) 369 { 370 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 371 } 372 373 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 374 { 375 const struct inet_sock *inet = inet_sk(sk); 376 struct dccp_hdr *dh = dccp_hdr(skb); 377 378 dccp_csum_outgoing(skb); 379 dh->dccph_checksum = dccp_v4_csum_finish(skb, 380 inet->inet_saddr, 381 inet->inet_daddr); 382 } 383 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 384 385 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 386 { 387 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 388 ip_hdr(skb)->saddr, 389 dccp_hdr(skb)->dccph_dport, 390 dccp_hdr(skb)->dccph_sport); 391 } 392 393 /* 394 * The three way handshake has completed - we got a valid ACK or DATAACK - 395 * now create the new socket. 396 * 397 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 398 */ 399 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 400 struct sk_buff *skb, 401 struct request_sock *req, 402 struct dst_entry *dst, 403 struct request_sock *req_unhash, 404 bool *own_req) 405 { 406 struct inet_request_sock *ireq; 407 struct inet_sock *newinet; 408 struct sock *newsk; 409 410 if (sk_acceptq_is_full(sk)) 411 goto exit_overflow; 412 413 newsk = dccp_create_openreq_child(sk, req, skb); 414 if (newsk == NULL) 415 goto exit_nonewsk; 416 417 newinet = inet_sk(newsk); 418 ireq = inet_rsk(req); 419 sk_daddr_set(newsk, ireq->ir_rmt_addr); 420 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 421 newinet->inet_saddr = ireq->ir_loc_addr; 422 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 423 newinet->mc_index = inet_iif(skb); 424 newinet->mc_ttl = ip_hdr(skb)->ttl; 425 newinet->inet_id = prandom_u32(); 426 427 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 428 goto put_and_exit; 429 430 sk_setup_caps(newsk, dst); 431 432 dccp_sync_mss(newsk, dst_mtu(dst)); 433 434 if (__inet_inherit_port(sk, newsk) < 0) 435 goto put_and_exit; 436 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 437 if (*own_req) 438 ireq->ireq_opt = NULL; 439 else 440 newinet->inet_opt = NULL; 441 return newsk; 442 443 exit_overflow: 444 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 445 exit_nonewsk: 446 dst_release(dst); 447 exit: 448 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 449 return NULL; 450 put_and_exit: 451 newinet->inet_opt = NULL; 452 inet_csk_prepare_forced_close(newsk); 453 dccp_done(newsk); 454 goto exit; 455 } 456 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 457 458 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 459 struct sk_buff *skb) 460 { 461 struct rtable *rt; 462 const struct iphdr *iph = ip_hdr(skb); 463 struct flowi4 fl4 = { 464 .flowi4_oif = inet_iif(skb), 465 .daddr = iph->saddr, 466 .saddr = iph->daddr, 467 .flowi4_tos = RT_CONN_FLAGS(sk), 468 .flowi4_proto = sk->sk_protocol, 469 .fl4_sport = dccp_hdr(skb)->dccph_dport, 470 .fl4_dport = dccp_hdr(skb)->dccph_sport, 471 }; 472 473 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 474 rt = ip_route_output_flow(net, &fl4, sk); 475 if (IS_ERR(rt)) { 476 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 477 return NULL; 478 } 479 480 return &rt->dst; 481 } 482 483 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 484 { 485 int err = -1; 486 struct sk_buff *skb; 487 struct dst_entry *dst; 488 struct flowi4 fl4; 489 490 dst = inet_csk_route_req(sk, &fl4, req); 491 if (dst == NULL) 492 goto out; 493 494 skb = dccp_make_response(sk, dst, req); 495 if (skb != NULL) { 496 const struct inet_request_sock *ireq = inet_rsk(req); 497 struct dccp_hdr *dh = dccp_hdr(skb); 498 499 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 500 ireq->ir_rmt_addr); 501 rcu_read_lock(); 502 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 503 ireq->ir_rmt_addr, 504 rcu_dereference(ireq->ireq_opt), 505 inet_sk(sk)->tos); 506 rcu_read_unlock(); 507 err = net_xmit_eval(err); 508 } 509 510 out: 511 dst_release(dst); 512 return err; 513 } 514 515 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 516 { 517 int err; 518 const struct iphdr *rxiph; 519 struct sk_buff *skb; 520 struct dst_entry *dst; 521 struct net *net = dev_net(skb_dst(rxskb)->dev); 522 struct dccp_v4_pernet *pn; 523 struct sock *ctl_sk; 524 525 /* Never send a reset in response to a reset. */ 526 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 527 return; 528 529 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 530 return; 531 532 pn = net_generic(net, dccp_v4_pernet_id); 533 ctl_sk = pn->v4_ctl_sk; 534 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 535 if (dst == NULL) 536 return; 537 538 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 539 if (skb == NULL) 540 goto out; 541 542 rxiph = ip_hdr(rxskb); 543 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 544 rxiph->daddr); 545 skb_dst_set(skb, dst_clone(dst)); 546 547 local_bh_disable(); 548 bh_lock_sock(ctl_sk); 549 err = ip_build_and_send_pkt(skb, ctl_sk, 550 rxiph->daddr, rxiph->saddr, NULL, 551 inet_sk(ctl_sk)->tos); 552 bh_unlock_sock(ctl_sk); 553 554 if (net_xmit_eval(err) == 0) { 555 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 556 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 557 } 558 local_bh_enable(); 559 out: 560 dst_release(dst); 561 } 562 563 static void dccp_v4_reqsk_destructor(struct request_sock *req) 564 { 565 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 566 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 567 } 568 569 void dccp_syn_ack_timeout(const struct request_sock *req) 570 { 571 } 572 EXPORT_SYMBOL(dccp_syn_ack_timeout); 573 574 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 575 .family = PF_INET, 576 .obj_size = sizeof(struct dccp_request_sock), 577 .rtx_syn_ack = dccp_v4_send_response, 578 .send_ack = dccp_reqsk_send_ack, 579 .destructor = dccp_v4_reqsk_destructor, 580 .send_reset = dccp_v4_ctl_send_reset, 581 .syn_ack_timeout = dccp_syn_ack_timeout, 582 }; 583 584 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 585 { 586 struct inet_request_sock *ireq; 587 struct request_sock *req; 588 struct dccp_request_sock *dreq; 589 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 590 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 591 592 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 593 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 594 return 0; /* discard, don't send a reset here */ 595 596 if (dccp_bad_service_code(sk, service)) { 597 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 598 goto drop; 599 } 600 /* 601 * TW buckets are converted to open requests without 602 * limitations, they conserve resources and peer is 603 * evidently real one. 604 */ 605 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 606 if (inet_csk_reqsk_queue_is_full(sk)) 607 goto drop; 608 609 if (sk_acceptq_is_full(sk)) 610 goto drop; 611 612 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 613 if (req == NULL) 614 goto drop; 615 616 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 617 goto drop_and_free; 618 619 dreq = dccp_rsk(req); 620 if (dccp_parse_options(sk, dreq, skb)) 621 goto drop_and_free; 622 623 if (security_inet_conn_request(sk, skb, req)) 624 goto drop_and_free; 625 626 ireq = inet_rsk(req); 627 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 628 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 629 ireq->ir_mark = inet_request_mark(sk, skb); 630 ireq->ireq_family = AF_INET; 631 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if); 632 633 /* 634 * Step 3: Process LISTEN state 635 * 636 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 637 * 638 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 639 */ 640 dreq->dreq_isr = dcb->dccpd_seq; 641 dreq->dreq_gsr = dreq->dreq_isr; 642 dreq->dreq_iss = dccp_v4_init_sequence(skb); 643 dreq->dreq_gss = dreq->dreq_iss; 644 dreq->dreq_service = service; 645 646 if (dccp_v4_send_response(sk, req)) 647 goto drop_and_free; 648 649 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 650 reqsk_put(req); 651 return 0; 652 653 drop_and_free: 654 reqsk_free(req); 655 drop: 656 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 657 return -1; 658 } 659 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 660 661 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 662 { 663 struct dccp_hdr *dh = dccp_hdr(skb); 664 665 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 666 if (dccp_rcv_established(sk, skb, dh, skb->len)) 667 goto reset; 668 return 0; 669 } 670 671 /* 672 * Step 3: Process LISTEN state 673 * If P.type == Request or P contains a valid Init Cookie option, 674 * (* Must scan the packet's options to check for Init 675 * Cookies. Only Init Cookies are processed here, 676 * however; other options are processed in Step 8. This 677 * scan need only be performed if the endpoint uses Init 678 * Cookies *) 679 * (* Generate a new socket and switch to that socket *) 680 * Set S := new socket for this port pair 681 * S.state = RESPOND 682 * Choose S.ISS (initial seqno) or set from Init Cookies 683 * Initialize S.GAR := S.ISS 684 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 685 * Continue with S.state == RESPOND 686 * (* A Response packet will be generated in Step 11 *) 687 * Otherwise, 688 * Generate Reset(No Connection) unless P.type == Reset 689 * Drop packet and return 690 * 691 * NOTE: the check for the packet types is done in 692 * dccp_rcv_state_process 693 */ 694 695 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 696 goto reset; 697 return 0; 698 699 reset: 700 dccp_v4_ctl_send_reset(sk, skb); 701 kfree_skb(skb); 702 return 0; 703 } 704 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 705 706 /** 707 * dccp_invalid_packet - check for malformed packets 708 * @skb: Packet to validate 709 * 710 * Implements RFC 4340, 8.5: Step 1: Check header basics 711 * Packets that fail these checks are ignored and do not receive Resets. 712 */ 713 int dccp_invalid_packet(struct sk_buff *skb) 714 { 715 const struct dccp_hdr *dh; 716 unsigned int cscov; 717 u8 dccph_doff; 718 719 if (skb->pkt_type != PACKET_HOST) 720 return 1; 721 722 /* If the packet is shorter than 12 bytes, drop packet and return */ 723 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 724 DCCP_WARN("pskb_may_pull failed\n"); 725 return 1; 726 } 727 728 dh = dccp_hdr(skb); 729 730 /* If P.type is not understood, drop packet and return */ 731 if (dh->dccph_type >= DCCP_PKT_INVALID) { 732 DCCP_WARN("invalid packet type\n"); 733 return 1; 734 } 735 736 /* 737 * If P.Data Offset is too small for packet type, drop packet and return 738 */ 739 dccph_doff = dh->dccph_doff; 740 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 741 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 742 return 1; 743 } 744 /* 745 * If P.Data Offset is too large for packet, drop packet and return 746 */ 747 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 748 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 749 return 1; 750 } 751 dh = dccp_hdr(skb); 752 /* 753 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 754 * has short sequence numbers), drop packet and return 755 */ 756 if ((dh->dccph_type < DCCP_PKT_DATA || 757 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 758 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 759 dccp_packet_name(dh->dccph_type)); 760 return 1; 761 } 762 763 /* 764 * If P.CsCov is too large for the packet size, drop packet and return. 765 * This must come _before_ checksumming (not as RFC 4340 suggests). 766 */ 767 cscov = dccp_csum_coverage(skb); 768 if (cscov > skb->len) { 769 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 770 dh->dccph_cscov, skb->len); 771 return 1; 772 } 773 774 /* If header checksum is incorrect, drop packet and return. 775 * (This step is completed in the AF-dependent functions.) */ 776 skb->csum = skb_checksum(skb, 0, cscov, 0); 777 778 return 0; 779 } 780 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 781 782 /* this is called when real data arrives */ 783 static int dccp_v4_rcv(struct sk_buff *skb) 784 { 785 const struct dccp_hdr *dh; 786 const struct iphdr *iph; 787 bool refcounted; 788 struct sock *sk; 789 int min_cov; 790 791 /* Step 1: Check header basics */ 792 793 if (dccp_invalid_packet(skb)) 794 goto discard_it; 795 796 iph = ip_hdr(skb); 797 /* Step 1: If header checksum is incorrect, drop packet and return */ 798 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 799 DCCP_WARN("dropped packet with invalid checksum\n"); 800 goto discard_it; 801 } 802 803 dh = dccp_hdr(skb); 804 805 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 806 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 807 808 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 809 dccp_packet_name(dh->dccph_type), 810 &iph->saddr, ntohs(dh->dccph_sport), 811 &iph->daddr, ntohs(dh->dccph_dport), 812 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 813 814 if (dccp_packet_without_ack(skb)) { 815 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 816 dccp_pr_debug_cat("\n"); 817 } else { 818 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 819 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 820 DCCP_SKB_CB(skb)->dccpd_ack_seq); 821 } 822 823 lookup: 824 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 825 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 826 if (!sk) { 827 dccp_pr_debug("failed to look up flow ID in table and " 828 "get corresponding socket\n"); 829 goto no_dccp_socket; 830 } 831 832 /* 833 * Step 2: 834 * ... or S.state == TIMEWAIT, 835 * Generate Reset(No Connection) unless P.type == Reset 836 * Drop packet and return 837 */ 838 if (sk->sk_state == DCCP_TIME_WAIT) { 839 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 840 inet_twsk_put(inet_twsk(sk)); 841 goto no_dccp_socket; 842 } 843 844 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 845 struct request_sock *req = inet_reqsk(sk); 846 struct sock *nsk; 847 848 sk = req->rsk_listener; 849 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 850 inet_csk_reqsk_queue_drop_and_put(sk, req); 851 goto lookup; 852 } 853 sock_hold(sk); 854 refcounted = true; 855 nsk = dccp_check_req(sk, skb, req); 856 if (!nsk) { 857 reqsk_put(req); 858 goto discard_and_relse; 859 } 860 if (nsk == sk) { 861 reqsk_put(req); 862 } else if (dccp_child_process(sk, nsk, skb)) { 863 dccp_v4_ctl_send_reset(sk, skb); 864 goto discard_and_relse; 865 } else { 866 sock_put(sk); 867 return 0; 868 } 869 } 870 /* 871 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 872 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 873 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 874 */ 875 min_cov = dccp_sk(sk)->dccps_pcrlen; 876 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 877 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 878 dh->dccph_cscov, min_cov); 879 /* FIXME: "Such packets SHOULD be reported using Data Dropped 880 * options (Section 11.7) with Drop Code 0, Protocol 881 * Constraints." */ 882 goto discard_and_relse; 883 } 884 885 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 886 goto discard_and_relse; 887 nf_reset_ct(skb); 888 889 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 890 891 no_dccp_socket: 892 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 893 goto discard_it; 894 /* 895 * Step 2: 896 * If no socket ... 897 * Generate Reset(No Connection) unless P.type == Reset 898 * Drop packet and return 899 */ 900 if (dh->dccph_type != DCCP_PKT_RESET) { 901 DCCP_SKB_CB(skb)->dccpd_reset_code = 902 DCCP_RESET_CODE_NO_CONNECTION; 903 dccp_v4_ctl_send_reset(sk, skb); 904 } 905 906 discard_it: 907 kfree_skb(skb); 908 return 0; 909 910 discard_and_relse: 911 if (refcounted) 912 sock_put(sk); 913 goto discard_it; 914 } 915 916 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 917 .queue_xmit = ip_queue_xmit, 918 .send_check = dccp_v4_send_check, 919 .rebuild_header = inet_sk_rebuild_header, 920 .conn_request = dccp_v4_conn_request, 921 .syn_recv_sock = dccp_v4_request_recv_sock, 922 .net_header_len = sizeof(struct iphdr), 923 .setsockopt = ip_setsockopt, 924 .getsockopt = ip_getsockopt, 925 .addr2sockaddr = inet_csk_addr2sockaddr, 926 .sockaddr_len = sizeof(struct sockaddr_in), 927 }; 928 929 static int dccp_v4_init_sock(struct sock *sk) 930 { 931 static __u8 dccp_v4_ctl_sock_initialized; 932 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 933 934 if (err == 0) { 935 if (unlikely(!dccp_v4_ctl_sock_initialized)) 936 dccp_v4_ctl_sock_initialized = 1; 937 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 938 } 939 940 return err; 941 } 942 943 static struct timewait_sock_ops dccp_timewait_sock_ops = { 944 .twsk_obj_size = sizeof(struct inet_timewait_sock), 945 }; 946 947 static struct proto dccp_v4_prot = { 948 .name = "DCCP", 949 .owner = THIS_MODULE, 950 .close = dccp_close, 951 .connect = dccp_v4_connect, 952 .disconnect = dccp_disconnect, 953 .ioctl = dccp_ioctl, 954 .init = dccp_v4_init_sock, 955 .setsockopt = dccp_setsockopt, 956 .getsockopt = dccp_getsockopt, 957 .sendmsg = dccp_sendmsg, 958 .recvmsg = dccp_recvmsg, 959 .backlog_rcv = dccp_v4_do_rcv, 960 .hash = inet_hash, 961 .unhash = inet_unhash, 962 .accept = inet_csk_accept, 963 .get_port = inet_csk_get_port, 964 .shutdown = dccp_shutdown, 965 .destroy = dccp_destroy_sock, 966 .orphan_count = &dccp_orphan_count, 967 .max_header = MAX_DCCP_HEADER, 968 .obj_size = sizeof(struct dccp_sock), 969 .slab_flags = SLAB_TYPESAFE_BY_RCU, 970 .rsk_prot = &dccp_request_sock_ops, 971 .twsk_prot = &dccp_timewait_sock_ops, 972 .h.hashinfo = &dccp_hashinfo, 973 }; 974 975 static const struct net_protocol dccp_v4_protocol = { 976 .handler = dccp_v4_rcv, 977 .err_handler = dccp_v4_err, 978 .no_policy = 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 }; 1005 1006 static struct inet_protosw dccp_v4_protosw = { 1007 .type = SOCK_DCCP, 1008 .protocol = IPPROTO_DCCP, 1009 .prot = &dccp_v4_prot, 1010 .ops = &inet_dccp_ops, 1011 .flags = INET_PROTOSW_ICSK, 1012 }; 1013 1014 static int __net_init dccp_v4_init_net(struct net *net) 1015 { 1016 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1017 1018 if (dccp_hashinfo.bhash == NULL) 1019 return -ESOCKTNOSUPPORT; 1020 1021 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1022 SOCK_DCCP, IPPROTO_DCCP, net); 1023 } 1024 1025 static void __net_exit dccp_v4_exit_net(struct net *net) 1026 { 1027 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1028 1029 inet_ctl_sock_destroy(pn->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 .id = &dccp_v4_pernet_id, 1042 .size = sizeof(struct dccp_v4_pernet), 1043 }; 1044 1045 static int __init dccp_v4_init(void) 1046 { 1047 int err = proto_register(&dccp_v4_prot, 1); 1048 1049 if (err) 1050 goto out; 1051 1052 inet_register_protosw(&dccp_v4_protosw); 1053 1054 err = register_pernet_subsys(&dccp_v4_ops); 1055 if (err) 1056 goto out_destroy_ctl_sock; 1057 1058 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1059 if (err) 1060 goto out_proto_unregister; 1061 1062 out: 1063 return err; 1064 out_proto_unregister: 1065 unregister_pernet_subsys(&dccp_v4_ops); 1066 out_destroy_ctl_sock: 1067 inet_unregister_protosw(&dccp_v4_protosw); 1068 proto_unregister(&dccp_v4_prot); 1069 goto out; 1070 } 1071 1072 static void __exit dccp_v4_exit(void) 1073 { 1074 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1075 unregister_pernet_subsys(&dccp_v4_ops); 1076 inet_unregister_protosw(&dccp_v4_protosw); 1077 proto_unregister(&dccp_v4_prot); 1078 } 1079 1080 module_init(dccp_v4_init); 1081 module_exit(dccp_v4_exit); 1082 1083 /* 1084 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1085 * values directly, Also cover the case where the protocol is not specified, 1086 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1087 */ 1088 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1089 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1090 MODULE_LICENSE("GPL"); 1091 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1092 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1093