1 /* 2 * net/dccp/ipv4.c 3 * 4 * An implementation of the DCCP protocol 5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <linux/config.h> 14 #include <linux/dccp.h> 15 #include <linux/icmp.h> 16 #include <linux/module.h> 17 #include <linux/skbuff.h> 18 #include <linux/random.h> 19 20 #include <net/icmp.h> 21 #include <net/inet_common.h> 22 #include <net/inet_hashtables.h> 23 #include <net/inet_sock.h> 24 #include <net/protocol.h> 25 #include <net/sock.h> 26 #include <net/timewait_sock.h> 27 #include <net/tcp_states.h> 28 #include <net/xfrm.h> 29 30 #include "ackvec.h" 31 #include "ccid.h" 32 #include "dccp.h" 33 #include "feat.h" 34 35 /* 36 * This is the global socket data structure used for responding to 37 * the Out-of-the-blue (OOTB) packets. A control sock will be created 38 * for this socket at the initialization time. 39 */ 40 static struct socket *dccp_v4_ctl_socket; 41 42 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum) 43 { 44 return inet_csk_get_port(&dccp_hashinfo, sk, snum, 45 inet_csk_bind_conflict); 46 } 47 48 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 49 { 50 struct inet_sock *inet = inet_sk(sk); 51 struct dccp_sock *dp = dccp_sk(sk); 52 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 53 struct rtable *rt; 54 u32 daddr, nexthop; 55 int tmp; 56 int err; 57 58 dp->dccps_role = DCCP_ROLE_CLIENT; 59 60 if (dccp_service_not_initialized(sk)) 61 return -EPROTO; 62 63 if (addr_len < sizeof(struct sockaddr_in)) 64 return -EINVAL; 65 66 if (usin->sin_family != AF_INET) 67 return -EAFNOSUPPORT; 68 69 nexthop = daddr = usin->sin_addr.s_addr; 70 if (inet->opt != NULL && inet->opt->srr) { 71 if (daddr == 0) 72 return -EINVAL; 73 nexthop = inet->opt->faddr; 74 } 75 76 tmp = ip_route_connect(&rt, nexthop, inet->saddr, 77 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 78 IPPROTO_DCCP, 79 inet->sport, usin->sin_port, sk); 80 if (tmp < 0) 81 return tmp; 82 83 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 84 ip_rt_put(rt); 85 return -ENETUNREACH; 86 } 87 88 if (inet->opt == NULL || !inet->opt->srr) 89 daddr = rt->rt_dst; 90 91 if (inet->saddr == 0) 92 inet->saddr = rt->rt_src; 93 inet->rcv_saddr = inet->saddr; 94 95 inet->dport = usin->sin_port; 96 inet->daddr = daddr; 97 98 inet_csk(sk)->icsk_ext_hdr_len = 0; 99 if (inet->opt != NULL) 100 inet_csk(sk)->icsk_ext_hdr_len = inet->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 err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport, 113 sk); 114 if (err != 0) 115 goto failure; 116 117 /* OK, now commit destination to socket. */ 118 sk_setup_caps(sk, &rt->u.dst); 119 120 dp->dccps_gar = 121 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, 122 inet->daddr, 123 inet->sport, 124 usin->sin_port); 125 dccp_update_gss(sk, dp->dccps_iss); 126 127 inet->id = dp->dccps_iss ^ jiffies; 128 129 err = dccp_connect(sk); 130 rt = NULL; 131 if (err != 0) 132 goto failure; 133 out: 134 return err; 135 failure: 136 /* 137 * This unhashes the socket and releases the local port, if necessary. 138 */ 139 dccp_set_state(sk, DCCP_CLOSED); 140 ip_rt_put(rt); 141 sk->sk_route_caps = 0; 142 inet->dport = 0; 143 goto out; 144 } 145 146 EXPORT_SYMBOL_GPL(dccp_v4_connect); 147 148 /* 149 * This routine does path mtu discovery as defined in RFC1191. 150 */ 151 static inline void dccp_do_pmtu_discovery(struct sock *sk, 152 const struct iphdr *iph, 153 u32 mtu) 154 { 155 struct dst_entry *dst; 156 const struct inet_sock *inet = inet_sk(sk); 157 const struct dccp_sock *dp = dccp_sk(sk); 158 159 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 160 * send out by Linux are always < 576bytes so they should go through 161 * unfragmented). 162 */ 163 if (sk->sk_state == DCCP_LISTEN) 164 return; 165 166 /* We don't check in the destentry if pmtu discovery is forbidden 167 * on this route. We just assume that no packet_to_big packets 168 * are send back when pmtu discovery is not active. 169 * There is a small race when the user changes this flag in the 170 * route, but I think that's acceptable. 171 */ 172 if ((dst = __sk_dst_check(sk, 0)) == NULL) 173 return; 174 175 dst->ops->update_pmtu(dst, mtu); 176 177 /* Something is about to be wrong... Remember soft error 178 * for the case, if this connection will not able to recover. 179 */ 180 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 181 sk->sk_err_soft = EMSGSIZE; 182 183 mtu = dst_mtu(dst); 184 185 if (inet->pmtudisc != IP_PMTUDISC_DONT && 186 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 187 dccp_sync_mss(sk, mtu); 188 189 /* 190 * From: draft-ietf-dccp-spec-11.txt 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_v4_reqsk_send_ack(struct sk_buff *rxskb, 201 struct request_sock *req) 202 { 203 int err; 204 struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh; 205 const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) + 206 sizeof(struct dccp_hdr_ext) + 207 sizeof(struct dccp_hdr_ack_bits); 208 struct sk_buff *skb; 209 210 if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL) 211 return; 212 213 skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC); 214 if (skb == NULL) 215 return; 216 217 /* Reserve space for headers. */ 218 skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header); 219 220 skb->dst = dst_clone(rxskb->dst); 221 222 skb->h.raw = skb_push(skb, dccp_hdr_ack_len); 223 dh = dccp_hdr(skb); 224 memset(dh, 0, dccp_hdr_ack_len); 225 226 /* Build DCCP header and checksum it. */ 227 dh->dccph_type = DCCP_PKT_ACK; 228 dh->dccph_sport = rxdh->dccph_dport; 229 dh->dccph_dport = rxdh->dccph_sport; 230 dh->dccph_doff = dccp_hdr_ack_len / 4; 231 dh->dccph_x = 1; 232 233 dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq); 234 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), 235 DCCP_SKB_CB(rxskb)->dccpd_seq); 236 237 bh_lock_sock(dccp_v4_ctl_socket->sk); 238 err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk, 239 rxskb->nh.iph->daddr, 240 rxskb->nh.iph->saddr, NULL); 241 bh_unlock_sock(dccp_v4_ctl_socket->sk); 242 243 if (err == NET_XMIT_CN || err == 0) { 244 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 245 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 246 } 247 } 248 249 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req, 250 struct dst_entry *dst) 251 { 252 int err = -1; 253 struct sk_buff *skb; 254 255 /* First, grab a route. */ 256 257 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL) 258 goto out; 259 260 skb = dccp_make_response(sk, dst, req); 261 if (skb != NULL) { 262 const struct inet_request_sock *ireq = inet_rsk(req); 263 struct dccp_hdr *dh = dccp_hdr(skb); 264 265 dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr, 266 ireq->rmt_addr); 267 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 268 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 269 ireq->rmt_addr, 270 ireq->opt); 271 if (err == NET_XMIT_CN) 272 err = 0; 273 } 274 275 out: 276 dst_release(dst); 277 return err; 278 } 279 280 /* 281 * This routine is called by the ICMP module when it gets some sort of error 282 * condition. If err < 0 then the socket should be closed and the error 283 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 284 * After adjustment header points to the first 8 bytes of the tcp header. We 285 * need to find the appropriate port. 286 * 287 * The locking strategy used here is very "optimistic". When someone else 288 * accesses the socket the ICMP is just dropped and for some paths there is no 289 * check at all. A more general error queue to queue errors for later handling 290 * is probably better. 291 */ 292 static void dccp_v4_err(struct sk_buff *skb, u32 info) 293 { 294 const struct iphdr *iph = (struct iphdr *)skb->data; 295 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + 296 (iph->ihl << 2)); 297 struct dccp_sock *dp; 298 struct inet_sock *inet; 299 const int type = skb->h.icmph->type; 300 const int code = skb->h.icmph->code; 301 struct sock *sk; 302 __u64 seq; 303 int err; 304 305 if (skb->len < (iph->ihl << 2) + 8) { 306 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 307 return; 308 } 309 310 sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport, 311 iph->saddr, dh->dccph_sport, inet_iif(skb)); 312 if (sk == NULL) { 313 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 314 return; 315 } 316 317 if (sk->sk_state == DCCP_TIME_WAIT) { 318 inet_twsk_put((struct inet_timewait_sock *)sk); 319 return; 320 } 321 322 bh_lock_sock(sk); 323 /* If too many ICMPs get dropped on busy 324 * servers this needs to be solved differently. 325 */ 326 if (sock_owned_by_user(sk)) 327 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); 328 329 if (sk->sk_state == DCCP_CLOSED) 330 goto out; 331 332 dp = dccp_sk(sk); 333 seq = dccp_hdr_seq(skb); 334 if (sk->sk_state != DCCP_LISTEN && 335 !between48(seq, dp->dccps_swl, dp->dccps_swh)) { 336 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS); 337 goto out; 338 } 339 340 switch (type) { 341 case ICMP_SOURCE_QUENCH: 342 /* Just silently ignore these. */ 343 goto out; 344 case ICMP_PARAMETERPROB: 345 err = EPROTO; 346 break; 347 case ICMP_DEST_UNREACH: 348 if (code > NR_ICMP_UNREACH) 349 goto out; 350 351 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 352 if (!sock_owned_by_user(sk)) 353 dccp_do_pmtu_discovery(sk, iph, info); 354 goto out; 355 } 356 357 err = icmp_err_convert[code].errno; 358 break; 359 case ICMP_TIME_EXCEEDED: 360 err = EHOSTUNREACH; 361 break; 362 default: 363 goto out; 364 } 365 366 switch (sk->sk_state) { 367 struct request_sock *req , **prev; 368 case DCCP_LISTEN: 369 if (sock_owned_by_user(sk)) 370 goto out; 371 req = inet_csk_search_req(sk, &prev, dh->dccph_dport, 372 iph->daddr, iph->saddr); 373 if (!req) 374 goto out; 375 376 /* 377 * ICMPs are not backlogged, hence we cannot get an established 378 * socket here. 379 */ 380 BUG_TRAP(!req->sk); 381 382 if (seq != dccp_rsk(req)->dreq_iss) { 383 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS); 384 goto out; 385 } 386 /* 387 * Still in RESPOND, just remove it silently. 388 * There is no good way to pass the error to the newly 389 * created socket, and POSIX does not want network 390 * errors returned from accept(). 391 */ 392 inet_csk_reqsk_queue_drop(sk, req, prev); 393 goto out; 394 395 case DCCP_REQUESTING: 396 case DCCP_RESPOND: 397 if (!sock_owned_by_user(sk)) { 398 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 399 sk->sk_err = err; 400 401 sk->sk_error_report(sk); 402 403 dccp_done(sk); 404 } else 405 sk->sk_err_soft = err; 406 goto out; 407 } 408 409 /* If we've already connected we will keep trying 410 * until we time out, or the user gives up. 411 * 412 * rfc1122 4.2.3.9 allows to consider as hard errors 413 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 414 * but it is obsoleted by pmtu discovery). 415 * 416 * Note, that in modern internet, where routing is unreliable 417 * and in each dark corner broken firewalls sit, sending random 418 * errors ordered by their masters even this two messages finally lose 419 * their original sense (even Linux sends invalid PORT_UNREACHs) 420 * 421 * Now we are in compliance with RFCs. 422 * --ANK (980905) 423 */ 424 425 inet = inet_sk(sk); 426 if (!sock_owned_by_user(sk) && inet->recverr) { 427 sk->sk_err = err; 428 sk->sk_error_report(sk); 429 } else /* Only an error on timeout */ 430 sk->sk_err_soft = err; 431 out: 432 bh_unlock_sock(sk); 433 sock_put(sk); 434 } 435 436 /* This routine computes an IPv4 DCCP checksum. */ 437 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb) 438 { 439 const struct inet_sock *inet = inet_sk(sk); 440 struct dccp_hdr *dh = dccp_hdr(skb); 441 442 dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr); 443 } 444 445 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 446 447 static inline u64 dccp_v4_init_sequence(const struct sock *sk, 448 const struct sk_buff *skb) 449 { 450 return secure_dccp_sequence_number(skb->nh.iph->daddr, 451 skb->nh.iph->saddr, 452 dccp_hdr(skb)->dccph_dport, 453 dccp_hdr(skb)->dccph_sport); 454 } 455 456 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 457 { 458 struct inet_request_sock *ireq; 459 struct dccp_sock dp; 460 struct request_sock *req; 461 struct dccp_request_sock *dreq; 462 const __be32 saddr = skb->nh.iph->saddr; 463 const __be32 daddr = skb->nh.iph->daddr; 464 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 465 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 466 __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY; 467 468 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 469 if (((struct rtable *)skb->dst)->rt_flags & 470 (RTCF_BROADCAST | RTCF_MULTICAST)) { 471 reset_code = DCCP_RESET_CODE_NO_CONNECTION; 472 goto drop; 473 } 474 475 if (dccp_bad_service_code(sk, service)) { 476 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 477 goto drop; 478 } 479 /* 480 * TW buckets are converted to open requests without 481 * limitations, they conserve resources and peer is 482 * evidently real one. 483 */ 484 if (inet_csk_reqsk_queue_is_full(sk)) 485 goto drop; 486 487 /* 488 * Accept backlog is full. If we have already queued enough 489 * of warm entries in syn queue, drop request. It is better than 490 * clogging syn queue with openreqs with exponentially increasing 491 * timeout. 492 */ 493 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 494 goto drop; 495 496 req = reqsk_alloc(sk->sk_prot->rsk_prot); 497 if (req == NULL) 498 goto drop; 499 500 if (dccp_parse_options(sk, skb)) 501 goto drop_and_free; 502 503 dccp_openreq_init(req, &dp, skb); 504 505 ireq = inet_rsk(req); 506 ireq->loc_addr = daddr; 507 ireq->rmt_addr = saddr; 508 req->rcv_wnd = 100; /* Fake, option parsing will get the 509 right value */ 510 ireq->opt = NULL; 511 512 /* 513 * Step 3: Process LISTEN state 514 * 515 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 516 * 517 * In fact we defer setting S.GSR, S.SWL, S.SWH to 518 * dccp_create_openreq_child. 519 */ 520 dreq = dccp_rsk(req); 521 dreq->dreq_isr = dcb->dccpd_seq; 522 dreq->dreq_iss = dccp_v4_init_sequence(sk, skb); 523 dreq->dreq_service = service; 524 525 if (dccp_v4_send_response(sk, req, NULL)) 526 goto drop_and_free; 527 528 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 529 return 0; 530 531 drop_and_free: 532 reqsk_free(req); 533 drop: 534 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); 535 dcb->dccpd_reset_code = reset_code; 536 return -1; 537 } 538 539 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 540 541 /* 542 * The three way handshake has completed - we got a valid ACK or DATAACK - 543 * now create the new socket. 544 * 545 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 546 */ 547 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, 548 struct request_sock *req, 549 struct dst_entry *dst) 550 { 551 struct inet_request_sock *ireq; 552 struct inet_sock *newinet; 553 struct dccp_sock *newdp; 554 struct sock *newsk; 555 556 if (sk_acceptq_is_full(sk)) 557 goto exit_overflow; 558 559 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL) 560 goto exit; 561 562 newsk = dccp_create_openreq_child(sk, req, skb); 563 if (newsk == NULL) 564 goto exit; 565 566 sk_setup_caps(newsk, dst); 567 568 newdp = dccp_sk(newsk); 569 newinet = inet_sk(newsk); 570 ireq = inet_rsk(req); 571 newinet->daddr = ireq->rmt_addr; 572 newinet->rcv_saddr = ireq->loc_addr; 573 newinet->saddr = ireq->loc_addr; 574 newinet->opt = ireq->opt; 575 ireq->opt = NULL; 576 newinet->mc_index = inet_iif(skb); 577 newinet->mc_ttl = skb->nh.iph->ttl; 578 newinet->id = jiffies; 579 580 dccp_sync_mss(newsk, dst_mtu(dst)); 581 582 __inet_hash(&dccp_hashinfo, newsk, 0); 583 __inet_inherit_port(&dccp_hashinfo, sk, newsk); 584 585 return newsk; 586 587 exit_overflow: 588 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS); 589 exit: 590 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS); 591 dst_release(dst); 592 return NULL; 593 } 594 595 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 596 597 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 598 { 599 const struct dccp_hdr *dh = dccp_hdr(skb); 600 const struct iphdr *iph = skb->nh.iph; 601 struct sock *nsk; 602 struct request_sock **prev; 603 /* Find possible connection requests. */ 604 struct request_sock *req = inet_csk_search_req(sk, &prev, 605 dh->dccph_sport, 606 iph->saddr, iph->daddr); 607 if (req != NULL) 608 return dccp_check_req(sk, skb, req, prev); 609 610 nsk = __inet_lookup_established(&dccp_hashinfo, 611 iph->saddr, dh->dccph_sport, 612 iph->daddr, ntohs(dh->dccph_dport), 613 inet_iif(skb)); 614 if (nsk != NULL) { 615 if (nsk->sk_state != DCCP_TIME_WAIT) { 616 bh_lock_sock(nsk); 617 return nsk; 618 } 619 inet_twsk_put((struct inet_timewait_sock *)nsk); 620 return NULL; 621 } 622 623 return sk; 624 } 625 626 int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr, 627 const __be32 daddr) 628 { 629 const struct dccp_hdr* dh = dccp_hdr(skb); 630 int checksum_len; 631 u32 tmp; 632 633 if (dh->dccph_cscov == 0) 634 checksum_len = skb->len; 635 else { 636 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32); 637 checksum_len = checksum_len < skb->len ? checksum_len : 638 skb->len; 639 } 640 641 tmp = csum_partial((unsigned char *)dh, checksum_len, 0); 642 return csum_tcpudp_magic(saddr, daddr, checksum_len, 643 IPPROTO_DCCP, tmp); 644 } 645 646 EXPORT_SYMBOL_GPL(dccp_v4_checksum); 647 648 static int dccp_v4_verify_checksum(struct sk_buff *skb, 649 const __be32 saddr, const __be32 daddr) 650 { 651 struct dccp_hdr *dh = dccp_hdr(skb); 652 int checksum_len; 653 u32 tmp; 654 655 if (dh->dccph_cscov == 0) 656 checksum_len = skb->len; 657 else { 658 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32); 659 checksum_len = checksum_len < skb->len ? checksum_len : 660 skb->len; 661 } 662 tmp = csum_partial((unsigned char *)dh, checksum_len, 0); 663 return csum_tcpudp_magic(saddr, daddr, checksum_len, 664 IPPROTO_DCCP, tmp) == 0 ? 0 : -1; 665 } 666 667 static struct dst_entry* dccp_v4_route_skb(struct sock *sk, 668 struct sk_buff *skb) 669 { 670 struct rtable *rt; 671 struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif, 672 .nl_u = { .ip4_u = 673 { .daddr = skb->nh.iph->saddr, 674 .saddr = skb->nh.iph->daddr, 675 .tos = RT_CONN_FLAGS(sk) } }, 676 .proto = sk->sk_protocol, 677 .uli_u = { .ports = 678 { .sport = dccp_hdr(skb)->dccph_dport, 679 .dport = dccp_hdr(skb)->dccph_sport } 680 } 681 }; 682 683 if (ip_route_output_flow(&rt, &fl, sk, 0)) { 684 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES); 685 return NULL; 686 } 687 688 return &rt->u.dst; 689 } 690 691 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb) 692 { 693 int err; 694 struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh; 695 const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) + 696 sizeof(struct dccp_hdr_ext) + 697 sizeof(struct dccp_hdr_reset); 698 struct sk_buff *skb; 699 struct dst_entry *dst; 700 u64 seqno; 701 702 /* Never send a reset in response to a reset. */ 703 if (rxdh->dccph_type == DCCP_PKT_RESET) 704 return; 705 706 if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL) 707 return; 708 709 dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb); 710 if (dst == NULL) 711 return; 712 713 skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, 714 GFP_ATOMIC); 715 if (skb == NULL) 716 goto out; 717 718 /* Reserve space for headers. */ 719 skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header); 720 skb->dst = dst_clone(dst); 721 722 skb->h.raw = skb_push(skb, dccp_hdr_reset_len); 723 dh = dccp_hdr(skb); 724 memset(dh, 0, dccp_hdr_reset_len); 725 726 /* Build DCCP header and checksum it. */ 727 dh->dccph_type = DCCP_PKT_RESET; 728 dh->dccph_sport = rxdh->dccph_dport; 729 dh->dccph_dport = rxdh->dccph_sport; 730 dh->dccph_doff = dccp_hdr_reset_len / 4; 731 dh->dccph_x = 1; 732 dccp_hdr_reset(skb)->dccph_reset_code = 733 DCCP_SKB_CB(rxskb)->dccpd_reset_code; 734 735 /* See "8.3.1. Abnormal Termination" in draft-ietf-dccp-spec-11 */ 736 seqno = 0; 737 if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 738 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1); 739 740 dccp_hdr_set_seq(dh, seqno); 741 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), 742 DCCP_SKB_CB(rxskb)->dccpd_seq); 743 744 dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr, 745 rxskb->nh.iph->daddr); 746 747 bh_lock_sock(dccp_v4_ctl_socket->sk); 748 err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk, 749 rxskb->nh.iph->daddr, 750 rxskb->nh.iph->saddr, NULL); 751 bh_unlock_sock(dccp_v4_ctl_socket->sk); 752 753 if (err == NET_XMIT_CN || err == 0) { 754 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); 755 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); 756 } 757 out: 758 dst_release(dst); 759 } 760 761 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 762 { 763 struct dccp_hdr *dh = dccp_hdr(skb); 764 765 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 766 if (dccp_rcv_established(sk, skb, dh, skb->len)) 767 goto reset; 768 return 0; 769 } 770 771 /* 772 * Step 3: Process LISTEN state 773 * If S.state == LISTEN, 774 * If P.type == Request or P contains a valid Init Cookie 775 * option, 776 * * Must scan the packet's options to check for an Init 777 * Cookie. Only the Init Cookie is processed here, 778 * however; other options are processed in Step 8. This 779 * scan need only be performed if the endpoint uses Init 780 * Cookies * 781 * * Generate a new socket and switch to that socket * 782 * Set S := new socket for this port pair 783 * S.state = RESPOND 784 * Choose S.ISS (initial seqno) or set from Init Cookie 785 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 786 * Continue with S.state == RESPOND 787 * * A Response packet will be generated in Step 11 * 788 * Otherwise, 789 * Generate Reset(No Connection) unless P.type == Reset 790 * Drop packet and return 791 * 792 * NOTE: the check for the packet types is done in 793 * dccp_rcv_state_process 794 */ 795 if (sk->sk_state == DCCP_LISTEN) { 796 struct sock *nsk = dccp_v4_hnd_req(sk, skb); 797 798 if (nsk == NULL) 799 goto discard; 800 801 if (nsk != sk) { 802 if (dccp_child_process(sk, nsk, skb)) 803 goto reset; 804 return 0; 805 } 806 } 807 808 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 809 goto reset; 810 return 0; 811 812 reset: 813 dccp_v4_ctl_send_reset(skb); 814 discard: 815 kfree_skb(skb); 816 return 0; 817 } 818 819 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 820 821 int dccp_invalid_packet(struct sk_buff *skb) 822 { 823 const struct dccp_hdr *dh; 824 825 if (skb->pkt_type != PACKET_HOST) 826 return 1; 827 828 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 829 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n"); 830 return 1; 831 } 832 833 dh = dccp_hdr(skb); 834 835 /* If the packet type is not understood, drop packet and return */ 836 if (dh->dccph_type >= DCCP_PKT_INVALID) { 837 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n"); 838 return 1; 839 } 840 841 /* 842 * If P.Data Offset is too small for packet type, or too large for 843 * packet, drop packet and return 844 */ 845 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 846 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) " 847 "too small 1\n", 848 dh->dccph_doff); 849 return 1; 850 } 851 852 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { 853 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) " 854 "too small 2\n", 855 dh->dccph_doff); 856 return 1; 857 } 858 859 dh = dccp_hdr(skb); 860 861 /* 862 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 863 * has short sequence numbers), drop packet and return 864 */ 865 if (dh->dccph_x == 0 && 866 dh->dccph_type != DCCP_PKT_DATA && 867 dh->dccph_type != DCCP_PKT_ACK && 868 dh->dccph_type != DCCP_PKT_DATAACK) { 869 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack " 870 "nor DataAck and P.X == 0\n", 871 dccp_packet_name(dh->dccph_type)); 872 return 1; 873 } 874 875 return 0; 876 } 877 878 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 879 880 /* this is called when real data arrives */ 881 static int dccp_v4_rcv(struct sk_buff *skb) 882 { 883 const struct dccp_hdr *dh; 884 struct sock *sk; 885 886 /* Step 1: Check header basics: */ 887 888 if (dccp_invalid_packet(skb)) 889 goto discard_it; 890 891 /* If the header checksum is incorrect, drop packet and return */ 892 if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr, 893 skb->nh.iph->daddr) < 0) { 894 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n", 895 __FUNCTION__); 896 goto discard_it; 897 } 898 899 dh = dccp_hdr(skb); 900 901 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(skb); 902 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 903 904 dccp_pr_debug("%8.8s " 905 "src=%u.%u.%u.%u@%-5d " 906 "dst=%u.%u.%u.%u@%-5d seq=%llu", 907 dccp_packet_name(dh->dccph_type), 908 NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport), 909 NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport), 910 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 911 912 if (dccp_packet_without_ack(skb)) { 913 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 914 dccp_pr_debug_cat("\n"); 915 } else { 916 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 917 dccp_pr_debug_cat(", ack=%llu\n", 918 (unsigned long long) 919 DCCP_SKB_CB(skb)->dccpd_ack_seq); 920 } 921 922 /* Step 2: 923 * Look up flow ID in table and get corresponding socket */ 924 sk = __inet_lookup(&dccp_hashinfo, 925 skb->nh.iph->saddr, dh->dccph_sport, 926 skb->nh.iph->daddr, ntohs(dh->dccph_dport), 927 inet_iif(skb)); 928 929 /* 930 * Step 2: 931 * If no socket ... 932 * Generate Reset(No Connection) unless P.type == Reset 933 * Drop packet and return 934 */ 935 if (sk == NULL) { 936 dccp_pr_debug("failed to look up flow ID in table and " 937 "get corresponding socket\n"); 938 goto no_dccp_socket; 939 } 940 941 /* 942 * Step 2: 943 * ... or S.state == TIMEWAIT, 944 * Generate Reset(No Connection) unless P.type == Reset 945 * Drop packet and return 946 */ 947 948 if (sk->sk_state == DCCP_TIME_WAIT) { 949 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: " 950 "do_time_wait\n"); 951 goto do_time_wait; 952 } 953 954 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 955 goto discard_and_relse; 956 nf_reset(skb); 957 958 return sk_receive_skb(sk, skb); 959 960 no_dccp_socket: 961 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 962 goto discard_it; 963 /* 964 * Step 2: 965 * Generate Reset(No Connection) unless P.type == Reset 966 * Drop packet and return 967 */ 968 if (dh->dccph_type != DCCP_PKT_RESET) { 969 DCCP_SKB_CB(skb)->dccpd_reset_code = 970 DCCP_RESET_CODE_NO_CONNECTION; 971 dccp_v4_ctl_send_reset(skb); 972 } 973 974 discard_it: 975 /* Discard frame. */ 976 kfree_skb(skb); 977 return 0; 978 979 discard_and_relse: 980 sock_put(sk); 981 goto discard_it; 982 983 do_time_wait: 984 inet_twsk_put((struct inet_timewait_sock *)sk); 985 goto no_dccp_socket; 986 } 987 988 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 989 .queue_xmit = ip_queue_xmit, 990 .send_check = dccp_v4_send_check, 991 .rebuild_header = inet_sk_rebuild_header, 992 .conn_request = dccp_v4_conn_request, 993 .syn_recv_sock = dccp_v4_request_recv_sock, 994 .net_header_len = sizeof(struct iphdr), 995 .setsockopt = ip_setsockopt, 996 .getsockopt = ip_getsockopt, 997 .addr2sockaddr = inet_csk_addr2sockaddr, 998 .sockaddr_len = sizeof(struct sockaddr_in), 999 #ifdef CONFIG_COMPAT 1000 .compat_setsockopt = compat_ip_setsockopt, 1001 .compat_getsockopt = compat_ip_getsockopt, 1002 #endif 1003 }; 1004 1005 static int dccp_v4_init_sock(struct sock *sk) 1006 { 1007 static __u8 dccp_v4_ctl_sock_initialized; 1008 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 1009 1010 if (err == 0) { 1011 if (unlikely(!dccp_v4_ctl_sock_initialized)) 1012 dccp_v4_ctl_sock_initialized = 1; 1013 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 1014 } 1015 1016 return err; 1017 } 1018 1019 static void dccp_v4_reqsk_destructor(struct request_sock *req) 1020 { 1021 kfree(inet_rsk(req)->opt); 1022 } 1023 1024 static struct request_sock_ops dccp_request_sock_ops = { 1025 .family = PF_INET, 1026 .obj_size = sizeof(struct dccp_request_sock), 1027 .rtx_syn_ack = dccp_v4_send_response, 1028 .send_ack = dccp_v4_reqsk_send_ack, 1029 .destructor = dccp_v4_reqsk_destructor, 1030 .send_reset = dccp_v4_ctl_send_reset, 1031 }; 1032 1033 static struct timewait_sock_ops dccp_timewait_sock_ops = { 1034 .twsk_obj_size = sizeof(struct inet_timewait_sock), 1035 }; 1036 1037 static struct proto dccp_v4_prot = { 1038 .name = "DCCP", 1039 .owner = THIS_MODULE, 1040 .close = dccp_close, 1041 .connect = dccp_v4_connect, 1042 .disconnect = dccp_disconnect, 1043 .ioctl = dccp_ioctl, 1044 .init = dccp_v4_init_sock, 1045 .setsockopt = dccp_setsockopt, 1046 .getsockopt = dccp_getsockopt, 1047 .sendmsg = dccp_sendmsg, 1048 .recvmsg = dccp_recvmsg, 1049 .backlog_rcv = dccp_v4_do_rcv, 1050 .hash = dccp_hash, 1051 .unhash = dccp_unhash, 1052 .accept = inet_csk_accept, 1053 .get_port = dccp_v4_get_port, 1054 .shutdown = dccp_shutdown, 1055 .destroy = dccp_destroy_sock, 1056 .orphan_count = &dccp_orphan_count, 1057 .max_header = MAX_DCCP_HEADER, 1058 .obj_size = sizeof(struct dccp_sock), 1059 .rsk_prot = &dccp_request_sock_ops, 1060 .twsk_prot = &dccp_timewait_sock_ops, 1061 #ifdef CONFIG_COMPAT 1062 .compat_setsockopt = compat_dccp_setsockopt, 1063 .compat_getsockopt = compat_dccp_getsockopt, 1064 #endif 1065 }; 1066 1067 static struct net_protocol dccp_v4_protocol = { 1068 .handler = dccp_v4_rcv, 1069 .err_handler = dccp_v4_err, 1070 .no_policy = 1, 1071 }; 1072 1073 static const struct proto_ops inet_dccp_ops = { 1074 .family = PF_INET, 1075 .owner = THIS_MODULE, 1076 .release = inet_release, 1077 .bind = inet_bind, 1078 .connect = inet_stream_connect, 1079 .socketpair = sock_no_socketpair, 1080 .accept = inet_accept, 1081 .getname = inet_getname, 1082 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1083 .poll = dccp_poll, 1084 .ioctl = inet_ioctl, 1085 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1086 .listen = inet_dccp_listen, 1087 .shutdown = inet_shutdown, 1088 .setsockopt = sock_common_setsockopt, 1089 .getsockopt = sock_common_getsockopt, 1090 .sendmsg = inet_sendmsg, 1091 .recvmsg = sock_common_recvmsg, 1092 .mmap = sock_no_mmap, 1093 .sendpage = sock_no_sendpage, 1094 #ifdef CONFIG_COMPAT 1095 .compat_setsockopt = compat_sock_common_setsockopt, 1096 .compat_getsockopt = compat_sock_common_getsockopt, 1097 #endif 1098 }; 1099 1100 static struct inet_protosw dccp_v4_protosw = { 1101 .type = SOCK_DCCP, 1102 .protocol = IPPROTO_DCCP, 1103 .prot = &dccp_v4_prot, 1104 .ops = &inet_dccp_ops, 1105 .capability = -1, 1106 .no_check = 0, 1107 .flags = INET_PROTOSW_ICSK, 1108 }; 1109 1110 static int __init dccp_v4_init(void) 1111 { 1112 int err = proto_register(&dccp_v4_prot, 1); 1113 1114 if (err != 0) 1115 goto out; 1116 1117 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1118 if (err != 0) 1119 goto out_proto_unregister; 1120 1121 inet_register_protosw(&dccp_v4_protosw); 1122 1123 err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET, 1124 SOCK_DCCP, IPPROTO_DCCP); 1125 if (err) 1126 goto out_unregister_protosw; 1127 out: 1128 return err; 1129 out_unregister_protosw: 1130 inet_unregister_protosw(&dccp_v4_protosw); 1131 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1132 out_proto_unregister: 1133 proto_unregister(&dccp_v4_prot); 1134 goto out; 1135 } 1136 1137 static void __exit dccp_v4_exit(void) 1138 { 1139 inet_unregister_protosw(&dccp_v4_protosw); 1140 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1141 proto_unregister(&dccp_v4_prot); 1142 } 1143 1144 module_init(dccp_v4_init); 1145 module_exit(dccp_v4_exit); 1146 1147 /* 1148 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1149 * values directly, Also cover the case where the protocol is not specified, 1150 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1151 */ 1152 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6"); 1153 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6"); 1154 MODULE_LICENSE("GPL"); 1155 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1156 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1157