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 err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET); 94 if (err) { 95 ip_rt_put(rt); 96 return err; 97 } 98 } else { 99 sk_rcv_saddr_set(sk, inet->inet_saddr); 100 } 101 102 inet->inet_dport = usin->sin_port; 103 sk_daddr_set(sk, daddr); 104 105 inet_csk(sk)->icsk_ext_hdr_len = 0; 106 if (inet_opt) 107 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 108 /* 109 * Socket identity is still unknown (sport may be zero). 110 * However we set state to DCCP_REQUESTING and not releasing socket 111 * lock select source port, enter ourselves into the hash tables and 112 * complete initialization after this. 113 */ 114 dccp_set_state(sk, DCCP_REQUESTING); 115 err = inet_hash_connect(&dccp_death_row, sk); 116 if (err != 0) 117 goto failure; 118 119 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 120 inet->inet_sport, inet->inet_dport, sk); 121 if (IS_ERR(rt)) { 122 err = PTR_ERR(rt); 123 rt = NULL; 124 goto failure; 125 } 126 /* OK, now commit destination to socket. */ 127 sk_setup_caps(sk, &rt->dst); 128 129 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 130 inet->inet_daddr, 131 inet->inet_sport, 132 inet->inet_dport); 133 inet->inet_id = get_random_u16(); 134 135 err = dccp_connect(sk); 136 rt = NULL; 137 if (err != 0) 138 goto failure; 139 out: 140 return err; 141 failure: 142 /* 143 * This unhashes the socket and releases the local port, if necessary. 144 */ 145 dccp_set_state(sk, DCCP_CLOSED); 146 inet_bhash2_reset_saddr(sk); 147 ip_rt_put(rt); 148 sk->sk_route_caps = 0; 149 inet->inet_dport = 0; 150 goto out; 151 } 152 EXPORT_SYMBOL_GPL(dccp_v4_connect); 153 154 /* 155 * This routine does path mtu discovery as defined in RFC1191. 156 */ 157 static inline void dccp_do_pmtu_discovery(struct sock *sk, 158 const struct iphdr *iph, 159 u32 mtu) 160 { 161 struct dst_entry *dst; 162 const struct inet_sock *inet = inet_sk(sk); 163 const struct dccp_sock *dp = dccp_sk(sk); 164 165 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 166 * send out by Linux are always < 576bytes so they should go through 167 * unfragmented). 168 */ 169 if (sk->sk_state == DCCP_LISTEN) 170 return; 171 172 dst = inet_csk_update_pmtu(sk, mtu); 173 if (!dst) 174 return; 175 176 /* Something is about to be wrong... Remember soft error 177 * for the case, if this connection will not able to recover. 178 */ 179 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 180 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE); 181 182 mtu = dst_mtu(dst); 183 184 if (inet->pmtudisc != IP_PMTUDISC_DONT && 185 ip_sk_accept_pmtu(sk) && 186 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 187 dccp_sync_mss(sk, mtu); 188 189 /* 190 * From RFC 4340, sec. 14.1: 191 * 192 * DCCP-Sync packets are the best choice for upward 193 * probing, since DCCP-Sync probes do not risk application 194 * data loss. 195 */ 196 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 197 } /* else let the usual retransmit timer handle it */ 198 } 199 200 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 201 { 202 struct dst_entry *dst = __sk_dst_check(sk, 0); 203 204 if (dst) 205 dst->ops->redirect(dst, sk, skb); 206 } 207 208 void dccp_req_err(struct sock *sk, u64 seq) 209 { 210 struct request_sock *req = inet_reqsk(sk); 211 struct net *net = sock_net(sk); 212 213 /* 214 * ICMPs are not backlogged, hence we cannot get an established 215 * socket here. 216 */ 217 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 218 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 219 } else { 220 /* 221 * Still in RESPOND, just remove it silently. 222 * There is no good way to pass the error to the newly 223 * created socket, and POSIX does not want network 224 * errors returned from accept(). 225 */ 226 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 227 } 228 reqsk_put(req); 229 } 230 EXPORT_SYMBOL(dccp_req_err); 231 232 /* 233 * This routine is called by the ICMP module when it gets some sort of error 234 * condition. If err < 0 then the socket should be closed and the error 235 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 236 * After adjustment header points to the first 8 bytes of the tcp header. We 237 * need to find the appropriate port. 238 * 239 * The locking strategy used here is very "optimistic". When someone else 240 * accesses the socket the ICMP is just dropped and for some paths there is no 241 * check at all. A more general error queue to queue errors for later handling 242 * is probably better. 243 */ 244 static int dccp_v4_err(struct sk_buff *skb, u32 info) 245 { 246 const struct iphdr *iph = (struct iphdr *)skb->data; 247 const u8 offset = iph->ihl << 2; 248 const struct dccp_hdr *dh; 249 struct dccp_sock *dp; 250 struct inet_sock *inet; 251 const int type = icmp_hdr(skb)->type; 252 const int code = icmp_hdr(skb)->code; 253 struct sock *sk; 254 __u64 seq; 255 int err; 256 struct net *net = dev_net(skb->dev); 257 258 /* Only need dccph_dport & dccph_sport which are the first 259 * 4 bytes in dccp header. 260 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 261 */ 262 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 263 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 264 dh = (struct dccp_hdr *)(skb->data + offset); 265 266 sk = __inet_lookup_established(net, &dccp_hashinfo, 267 iph->daddr, dh->dccph_dport, 268 iph->saddr, ntohs(dh->dccph_sport), 269 inet_iif(skb), 0); 270 if (!sk) { 271 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 272 return -ENOENT; 273 } 274 275 if (sk->sk_state == DCCP_TIME_WAIT) { 276 inet_twsk_put(inet_twsk(sk)); 277 return 0; 278 } 279 seq = dccp_hdr_seq(dh); 280 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 281 dccp_req_err(sk, seq); 282 return 0; 283 } 284 285 bh_lock_sock(sk); 286 /* If too many ICMPs get dropped on busy 287 * servers this needs to be solved differently. 288 */ 289 if (sock_owned_by_user(sk)) 290 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 291 292 if (sk->sk_state == DCCP_CLOSED) 293 goto out; 294 295 dp = dccp_sk(sk); 296 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 297 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 298 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 299 goto out; 300 } 301 302 switch (type) { 303 case ICMP_REDIRECT: 304 if (!sock_owned_by_user(sk)) 305 dccp_do_redirect(skb, sk); 306 goto out; 307 case ICMP_SOURCE_QUENCH: 308 /* Just silently ignore these. */ 309 goto out; 310 case ICMP_PARAMETERPROB: 311 err = EPROTO; 312 break; 313 case ICMP_DEST_UNREACH: 314 if (code > NR_ICMP_UNREACH) 315 goto out; 316 317 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 318 if (!sock_owned_by_user(sk)) 319 dccp_do_pmtu_discovery(sk, iph, info); 320 goto out; 321 } 322 323 err = icmp_err_convert[code].errno; 324 break; 325 case ICMP_TIME_EXCEEDED: 326 err = EHOSTUNREACH; 327 break; 328 default: 329 goto out; 330 } 331 332 switch (sk->sk_state) { 333 case DCCP_REQUESTING: 334 case DCCP_RESPOND: 335 if (!sock_owned_by_user(sk)) { 336 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 337 sk->sk_err = err; 338 339 sk_error_report(sk); 340 341 dccp_done(sk); 342 } else { 343 WRITE_ONCE(sk->sk_err_soft, err); 344 } 345 goto out; 346 } 347 348 /* If we've already connected we will keep trying 349 * until we time out, or the user gives up. 350 * 351 * rfc1122 4.2.3.9 allows to consider as hard errors 352 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 353 * but it is obsoleted by pmtu discovery). 354 * 355 * Note, that in modern internet, where routing is unreliable 356 * and in each dark corner broken firewalls sit, sending random 357 * errors ordered by their masters even this two messages finally lose 358 * their original sense (even Linux sends invalid PORT_UNREACHs) 359 * 360 * Now we are in compliance with RFCs. 361 * --ANK (980905) 362 */ 363 364 inet = inet_sk(sk); 365 if (!sock_owned_by_user(sk) && inet->recverr) { 366 sk->sk_err = err; 367 sk_error_report(sk); 368 } else { /* Only an error on timeout */ 369 WRITE_ONCE(sk->sk_err_soft, err); 370 } 371 out: 372 bh_unlock_sock(sk); 373 sock_put(sk); 374 return 0; 375 } 376 377 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 378 __be32 src, __be32 dst) 379 { 380 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 381 } 382 383 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 384 { 385 const struct inet_sock *inet = inet_sk(sk); 386 struct dccp_hdr *dh = dccp_hdr(skb); 387 388 dccp_csum_outgoing(skb); 389 dh->dccph_checksum = dccp_v4_csum_finish(skb, 390 inet->inet_saddr, 391 inet->inet_daddr); 392 } 393 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 394 395 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 396 { 397 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 398 ip_hdr(skb)->saddr, 399 dccp_hdr(skb)->dccph_dport, 400 dccp_hdr(skb)->dccph_sport); 401 } 402 403 /* 404 * The three way handshake has completed - we got a valid ACK or DATAACK - 405 * now create the new socket. 406 * 407 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 408 */ 409 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 410 struct sk_buff *skb, 411 struct request_sock *req, 412 struct dst_entry *dst, 413 struct request_sock *req_unhash, 414 bool *own_req) 415 { 416 struct inet_request_sock *ireq; 417 struct inet_sock *newinet; 418 struct sock *newsk; 419 420 if (sk_acceptq_is_full(sk)) 421 goto exit_overflow; 422 423 newsk = dccp_create_openreq_child(sk, req, skb); 424 if (newsk == NULL) 425 goto exit_nonewsk; 426 427 newinet = inet_sk(newsk); 428 ireq = inet_rsk(req); 429 sk_daddr_set(newsk, ireq->ir_rmt_addr); 430 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 431 newinet->inet_saddr = ireq->ir_loc_addr; 432 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 433 newinet->mc_index = inet_iif(skb); 434 newinet->mc_ttl = ip_hdr(skb)->ttl; 435 newinet->inet_id = get_random_u16(); 436 437 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 438 goto put_and_exit; 439 440 sk_setup_caps(newsk, dst); 441 442 dccp_sync_mss(newsk, dst_mtu(dst)); 443 444 if (__inet_inherit_port(sk, newsk) < 0) 445 goto put_and_exit; 446 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 447 if (*own_req) 448 ireq->ireq_opt = NULL; 449 else 450 newinet->inet_opt = NULL; 451 return newsk; 452 453 exit_overflow: 454 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 455 exit_nonewsk: 456 dst_release(dst); 457 exit: 458 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 459 return NULL; 460 put_and_exit: 461 newinet->inet_opt = NULL; 462 inet_csk_prepare_forced_close(newsk); 463 dccp_done(newsk); 464 goto exit; 465 } 466 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 467 468 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 469 struct sk_buff *skb) 470 { 471 struct rtable *rt; 472 const struct iphdr *iph = ip_hdr(skb); 473 struct flowi4 fl4 = { 474 .flowi4_oif = inet_iif(skb), 475 .daddr = iph->saddr, 476 .saddr = iph->daddr, 477 .flowi4_tos = RT_CONN_FLAGS(sk), 478 .flowi4_proto = sk->sk_protocol, 479 .fl4_sport = dccp_hdr(skb)->dccph_dport, 480 .fl4_dport = dccp_hdr(skb)->dccph_sport, 481 }; 482 483 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 484 rt = ip_route_output_flow(net, &fl4, sk); 485 if (IS_ERR(rt)) { 486 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 487 return NULL; 488 } 489 490 return &rt->dst; 491 } 492 493 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 494 { 495 int err = -1; 496 struct sk_buff *skb; 497 struct dst_entry *dst; 498 struct flowi4 fl4; 499 500 dst = inet_csk_route_req(sk, &fl4, req); 501 if (dst == NULL) 502 goto out; 503 504 skb = dccp_make_response(sk, dst, req); 505 if (skb != NULL) { 506 const struct inet_request_sock *ireq = inet_rsk(req); 507 struct dccp_hdr *dh = dccp_hdr(skb); 508 509 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 510 ireq->ir_rmt_addr); 511 rcu_read_lock(); 512 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 513 ireq->ir_rmt_addr, 514 rcu_dereference(ireq->ireq_opt), 515 inet_sk(sk)->tos); 516 rcu_read_unlock(); 517 err = net_xmit_eval(err); 518 } 519 520 out: 521 dst_release(dst); 522 return err; 523 } 524 525 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 526 { 527 int err; 528 const struct iphdr *rxiph; 529 struct sk_buff *skb; 530 struct dst_entry *dst; 531 struct net *net = dev_net(skb_dst(rxskb)->dev); 532 struct dccp_v4_pernet *pn; 533 struct sock *ctl_sk; 534 535 /* Never send a reset in response to a reset. */ 536 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 537 return; 538 539 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 540 return; 541 542 pn = net_generic(net, dccp_v4_pernet_id); 543 ctl_sk = pn->v4_ctl_sk; 544 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 545 if (dst == NULL) 546 return; 547 548 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 549 if (skb == NULL) 550 goto out; 551 552 rxiph = ip_hdr(rxskb); 553 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 554 rxiph->daddr); 555 skb_dst_set(skb, dst_clone(dst)); 556 557 local_bh_disable(); 558 bh_lock_sock(ctl_sk); 559 err = ip_build_and_send_pkt(skb, ctl_sk, 560 rxiph->daddr, rxiph->saddr, NULL, 561 inet_sk(ctl_sk)->tos); 562 bh_unlock_sock(ctl_sk); 563 564 if (net_xmit_eval(err) == 0) { 565 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 566 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 567 } 568 local_bh_enable(); 569 out: 570 dst_release(dst); 571 } 572 573 static void dccp_v4_reqsk_destructor(struct request_sock *req) 574 { 575 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 576 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 577 } 578 579 void dccp_syn_ack_timeout(const struct request_sock *req) 580 { 581 } 582 EXPORT_SYMBOL(dccp_syn_ack_timeout); 583 584 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 585 .family = PF_INET, 586 .obj_size = sizeof(struct dccp_request_sock), 587 .rtx_syn_ack = dccp_v4_send_response, 588 .send_ack = dccp_reqsk_send_ack, 589 .destructor = dccp_v4_reqsk_destructor, 590 .send_reset = dccp_v4_ctl_send_reset, 591 .syn_ack_timeout = dccp_syn_ack_timeout, 592 }; 593 594 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 595 { 596 struct inet_request_sock *ireq; 597 struct request_sock *req; 598 struct dccp_request_sock *dreq; 599 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 600 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 601 602 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 603 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 604 return 0; /* discard, don't send a reset here */ 605 606 if (dccp_bad_service_code(sk, service)) { 607 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 608 goto drop; 609 } 610 /* 611 * TW buckets are converted to open requests without 612 * limitations, they conserve resources and peer is 613 * evidently real one. 614 */ 615 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 616 if (inet_csk_reqsk_queue_is_full(sk)) 617 goto drop; 618 619 if (sk_acceptq_is_full(sk)) 620 goto drop; 621 622 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 623 if (req == NULL) 624 goto drop; 625 626 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 627 goto drop_and_free; 628 629 dreq = dccp_rsk(req); 630 if (dccp_parse_options(sk, dreq, skb)) 631 goto drop_and_free; 632 633 if (security_inet_conn_request(sk, skb, req)) 634 goto drop_and_free; 635 636 ireq = inet_rsk(req); 637 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 638 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 639 ireq->ir_mark = inet_request_mark(sk, skb); 640 ireq->ireq_family = AF_INET; 641 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if); 642 643 /* 644 * Step 3: Process LISTEN state 645 * 646 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 647 * 648 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 649 */ 650 dreq->dreq_isr = dcb->dccpd_seq; 651 dreq->dreq_gsr = dreq->dreq_isr; 652 dreq->dreq_iss = dccp_v4_init_sequence(skb); 653 dreq->dreq_gss = dreq->dreq_iss; 654 dreq->dreq_service = service; 655 656 if (dccp_v4_send_response(sk, req)) 657 goto drop_and_free; 658 659 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 660 reqsk_put(req); 661 return 0; 662 663 drop_and_free: 664 reqsk_free(req); 665 drop: 666 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 667 return -1; 668 } 669 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 670 671 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 672 { 673 struct dccp_hdr *dh = dccp_hdr(skb); 674 675 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 676 if (dccp_rcv_established(sk, skb, dh, skb->len)) 677 goto reset; 678 return 0; 679 } 680 681 /* 682 * Step 3: Process LISTEN state 683 * If P.type == Request or P contains a valid Init Cookie option, 684 * (* Must scan the packet's options to check for Init 685 * Cookies. Only Init Cookies are processed here, 686 * however; other options are processed in Step 8. This 687 * scan need only be performed if the endpoint uses Init 688 * Cookies *) 689 * (* Generate a new socket and switch to that socket *) 690 * Set S := new socket for this port pair 691 * S.state = RESPOND 692 * Choose S.ISS (initial seqno) or set from Init Cookies 693 * Initialize S.GAR := S.ISS 694 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 695 * Continue with S.state == RESPOND 696 * (* A Response packet will be generated in Step 11 *) 697 * Otherwise, 698 * Generate Reset(No Connection) unless P.type == Reset 699 * Drop packet and return 700 * 701 * NOTE: the check for the packet types is done in 702 * dccp_rcv_state_process 703 */ 704 705 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 706 goto reset; 707 return 0; 708 709 reset: 710 dccp_v4_ctl_send_reset(sk, skb); 711 kfree_skb(skb); 712 return 0; 713 } 714 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 715 716 /** 717 * dccp_invalid_packet - check for malformed packets 718 * @skb: Packet to validate 719 * 720 * Implements RFC 4340, 8.5: Step 1: Check header basics 721 * Packets that fail these checks are ignored and do not receive Resets. 722 */ 723 int dccp_invalid_packet(struct sk_buff *skb) 724 { 725 const struct dccp_hdr *dh; 726 unsigned int cscov; 727 u8 dccph_doff; 728 729 if (skb->pkt_type != PACKET_HOST) 730 return 1; 731 732 /* If the packet is shorter than 12 bytes, drop packet and return */ 733 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 734 DCCP_WARN("pskb_may_pull failed\n"); 735 return 1; 736 } 737 738 dh = dccp_hdr(skb); 739 740 /* If P.type is not understood, drop packet and return */ 741 if (dh->dccph_type >= DCCP_PKT_INVALID) { 742 DCCP_WARN("invalid packet type\n"); 743 return 1; 744 } 745 746 /* 747 * If P.Data Offset is too small for packet type, drop packet and return 748 */ 749 dccph_doff = dh->dccph_doff; 750 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 751 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 752 return 1; 753 } 754 /* 755 * If P.Data Offset is too large for packet, drop packet and return 756 */ 757 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 758 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 759 return 1; 760 } 761 dh = dccp_hdr(skb); 762 /* 763 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 764 * has short sequence numbers), drop packet and return 765 */ 766 if ((dh->dccph_type < DCCP_PKT_DATA || 767 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 768 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 769 dccp_packet_name(dh->dccph_type)); 770 return 1; 771 } 772 773 /* 774 * If P.CsCov is too large for the packet size, drop packet and return. 775 * This must come _before_ checksumming (not as RFC 4340 suggests). 776 */ 777 cscov = dccp_csum_coverage(skb); 778 if (cscov > skb->len) { 779 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 780 dh->dccph_cscov, skb->len); 781 return 1; 782 } 783 784 /* If header checksum is incorrect, drop packet and return. 785 * (This step is completed in the AF-dependent functions.) */ 786 skb->csum = skb_checksum(skb, 0, cscov, 0); 787 788 return 0; 789 } 790 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 791 792 /* this is called when real data arrives */ 793 static int dccp_v4_rcv(struct sk_buff *skb) 794 { 795 const struct dccp_hdr *dh; 796 const struct iphdr *iph; 797 bool refcounted; 798 struct sock *sk; 799 int min_cov; 800 801 /* Step 1: Check header basics */ 802 803 if (dccp_invalid_packet(skb)) 804 goto discard_it; 805 806 iph = ip_hdr(skb); 807 /* Step 1: If header checksum is incorrect, drop packet and return */ 808 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 809 DCCP_WARN("dropped packet with invalid checksum\n"); 810 goto discard_it; 811 } 812 813 dh = dccp_hdr(skb); 814 815 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 816 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 817 818 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 819 dccp_packet_name(dh->dccph_type), 820 &iph->saddr, ntohs(dh->dccph_sport), 821 &iph->daddr, ntohs(dh->dccph_dport), 822 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 823 824 if (dccp_packet_without_ack(skb)) { 825 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 826 dccp_pr_debug_cat("\n"); 827 } else { 828 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 829 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 830 DCCP_SKB_CB(skb)->dccpd_ack_seq); 831 } 832 833 lookup: 834 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 835 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 836 if (!sk) { 837 dccp_pr_debug("failed to look up flow ID in table and " 838 "get corresponding socket\n"); 839 goto no_dccp_socket; 840 } 841 842 /* 843 * Step 2: 844 * ... or S.state == TIMEWAIT, 845 * Generate Reset(No Connection) unless P.type == Reset 846 * Drop packet and return 847 */ 848 if (sk->sk_state == DCCP_TIME_WAIT) { 849 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 850 inet_twsk_put(inet_twsk(sk)); 851 goto no_dccp_socket; 852 } 853 854 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 855 struct request_sock *req = inet_reqsk(sk); 856 struct sock *nsk; 857 858 sk = req->rsk_listener; 859 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 860 inet_csk_reqsk_queue_drop_and_put(sk, req); 861 goto lookup; 862 } 863 sock_hold(sk); 864 refcounted = true; 865 nsk = dccp_check_req(sk, skb, req); 866 if (!nsk) { 867 reqsk_put(req); 868 goto discard_and_relse; 869 } 870 if (nsk == sk) { 871 reqsk_put(req); 872 } else if (dccp_child_process(sk, nsk, skb)) { 873 dccp_v4_ctl_send_reset(sk, skb); 874 goto discard_and_relse; 875 } else { 876 sock_put(sk); 877 return 0; 878 } 879 } 880 /* 881 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 882 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 883 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 884 */ 885 min_cov = dccp_sk(sk)->dccps_pcrlen; 886 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 887 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 888 dh->dccph_cscov, min_cov); 889 /* FIXME: "Such packets SHOULD be reported using Data Dropped 890 * options (Section 11.7) with Drop Code 0, Protocol 891 * Constraints." */ 892 goto discard_and_relse; 893 } 894 895 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 896 goto discard_and_relse; 897 nf_reset_ct(skb); 898 899 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 900 901 no_dccp_socket: 902 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 903 goto discard_it; 904 /* 905 * Step 2: 906 * If no socket ... 907 * Generate Reset(No Connection) unless P.type == Reset 908 * Drop packet and return 909 */ 910 if (dh->dccph_type != DCCP_PKT_RESET) { 911 DCCP_SKB_CB(skb)->dccpd_reset_code = 912 DCCP_RESET_CODE_NO_CONNECTION; 913 dccp_v4_ctl_send_reset(sk, skb); 914 } 915 916 discard_it: 917 kfree_skb(skb); 918 return 0; 919 920 discard_and_relse: 921 if (refcounted) 922 sock_put(sk); 923 goto discard_it; 924 } 925 926 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 927 .queue_xmit = ip_queue_xmit, 928 .send_check = dccp_v4_send_check, 929 .rebuild_header = inet_sk_rebuild_header, 930 .conn_request = dccp_v4_conn_request, 931 .syn_recv_sock = dccp_v4_request_recv_sock, 932 .net_header_len = sizeof(struct iphdr), 933 .setsockopt = ip_setsockopt, 934 .getsockopt = ip_getsockopt, 935 .addr2sockaddr = inet_csk_addr2sockaddr, 936 .sockaddr_len = sizeof(struct sockaddr_in), 937 }; 938 939 static int dccp_v4_init_sock(struct sock *sk) 940 { 941 static __u8 dccp_v4_ctl_sock_initialized; 942 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 943 944 if (err == 0) { 945 if (unlikely(!dccp_v4_ctl_sock_initialized)) 946 dccp_v4_ctl_sock_initialized = 1; 947 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 948 } 949 950 return err; 951 } 952 953 static struct timewait_sock_ops dccp_timewait_sock_ops = { 954 .twsk_obj_size = sizeof(struct inet_timewait_sock), 955 }; 956 957 static struct proto dccp_v4_prot = { 958 .name = "DCCP", 959 .owner = THIS_MODULE, 960 .close = dccp_close, 961 .connect = dccp_v4_connect, 962 .disconnect = dccp_disconnect, 963 .ioctl = dccp_ioctl, 964 .init = dccp_v4_init_sock, 965 .setsockopt = dccp_setsockopt, 966 .getsockopt = dccp_getsockopt, 967 .sendmsg = dccp_sendmsg, 968 .recvmsg = dccp_recvmsg, 969 .backlog_rcv = dccp_v4_do_rcv, 970 .hash = inet_hash, 971 .unhash = inet_unhash, 972 .accept = inet_csk_accept, 973 .get_port = inet_csk_get_port, 974 .shutdown = dccp_shutdown, 975 .destroy = dccp_destroy_sock, 976 .orphan_count = &dccp_orphan_count, 977 .max_header = MAX_DCCP_HEADER, 978 .obj_size = sizeof(struct dccp_sock), 979 .slab_flags = SLAB_TYPESAFE_BY_RCU, 980 .rsk_prot = &dccp_request_sock_ops, 981 .twsk_prot = &dccp_timewait_sock_ops, 982 .h.hashinfo = &dccp_hashinfo, 983 }; 984 985 static const struct net_protocol dccp_v4_protocol = { 986 .handler = dccp_v4_rcv, 987 .err_handler = dccp_v4_err, 988 .no_policy = 1, 989 .icmp_strict_tag_validation = 1, 990 }; 991 992 static const struct proto_ops inet_dccp_ops = { 993 .family = PF_INET, 994 .owner = THIS_MODULE, 995 .release = inet_release, 996 .bind = inet_bind, 997 .connect = inet_stream_connect, 998 .socketpair = sock_no_socketpair, 999 .accept = inet_accept, 1000 .getname = inet_getname, 1001 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1002 .poll = dccp_poll, 1003 .ioctl = inet_ioctl, 1004 .gettstamp = sock_gettstamp, 1005 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1006 .listen = inet_dccp_listen, 1007 .shutdown = inet_shutdown, 1008 .setsockopt = sock_common_setsockopt, 1009 .getsockopt = sock_common_getsockopt, 1010 .sendmsg = inet_sendmsg, 1011 .recvmsg = sock_common_recvmsg, 1012 .mmap = sock_no_mmap, 1013 .sendpage = sock_no_sendpage, 1014 }; 1015 1016 static struct inet_protosw dccp_v4_protosw = { 1017 .type = SOCK_DCCP, 1018 .protocol = IPPROTO_DCCP, 1019 .prot = &dccp_v4_prot, 1020 .ops = &inet_dccp_ops, 1021 .flags = INET_PROTOSW_ICSK, 1022 }; 1023 1024 static int __net_init dccp_v4_init_net(struct net *net) 1025 { 1026 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1027 1028 if (dccp_hashinfo.bhash == NULL) 1029 return -ESOCKTNOSUPPORT; 1030 1031 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1032 SOCK_DCCP, IPPROTO_DCCP, net); 1033 } 1034 1035 static void __net_exit dccp_v4_exit_net(struct net *net) 1036 { 1037 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1038 1039 inet_ctl_sock_destroy(pn->v4_ctl_sk); 1040 } 1041 1042 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1043 { 1044 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1045 } 1046 1047 static struct pernet_operations dccp_v4_ops = { 1048 .init = dccp_v4_init_net, 1049 .exit = dccp_v4_exit_net, 1050 .exit_batch = dccp_v4_exit_batch, 1051 .id = &dccp_v4_pernet_id, 1052 .size = sizeof(struct dccp_v4_pernet), 1053 }; 1054 1055 static int __init dccp_v4_init(void) 1056 { 1057 int err = proto_register(&dccp_v4_prot, 1); 1058 1059 if (err) 1060 goto out; 1061 1062 inet_register_protosw(&dccp_v4_protosw); 1063 1064 err = register_pernet_subsys(&dccp_v4_ops); 1065 if (err) 1066 goto out_destroy_ctl_sock; 1067 1068 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1069 if (err) 1070 goto out_proto_unregister; 1071 1072 out: 1073 return err; 1074 out_proto_unregister: 1075 unregister_pernet_subsys(&dccp_v4_ops); 1076 out_destroy_ctl_sock: 1077 inet_unregister_protosw(&dccp_v4_protosw); 1078 proto_unregister(&dccp_v4_prot); 1079 goto out; 1080 } 1081 1082 static void __exit dccp_v4_exit(void) 1083 { 1084 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1085 unregister_pernet_subsys(&dccp_v4_ops); 1086 inet_unregister_protosw(&dccp_v4_protosw); 1087 proto_unregister(&dccp_v4_prot); 1088 } 1089 1090 module_init(dccp_v4_init); 1091 module_exit(dccp_v4_exit); 1092 1093 /* 1094 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1095 * values directly, Also cover the case where the protocol is not specified, 1096 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1097 */ 1098 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1099 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1100 MODULE_LICENSE("GPL"); 1101 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1102 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1103