net/dccp/ipv4.c

   1 /*
   2  *  net/dccp/ipv4.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/dccp.h>
  14 #include <linux/icmp.h>
  15 #include <linux/slab.h>
  16 #include <linux/module.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/random.h>
  19
  20 #include <net/icmp.h>
  21 #include <net/inet_common.h>
  22 #include <net/inet_hashtables.h>
  23 #include <net/inet_sock.h>
  24 #include <net/protocol.h>
  25 #include <net/sock.h>
  26 #include <net/timewait_sock.h>
  27 #include <net/tcp_states.h>
  28 #include <net/xfrm.h>
  29
  30 #include "ackvec.h"
  31 #include "ccid.h"
  32 #include "dccp.h"
  33 #include "feat.h"
  34
  35 /*
  36  * The per-net dccp.v4_ctl_sk socket is 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
  41 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  42 {
  43         struct inet_sock *inet = inet_sk(sk);
  44         struct dccp_sock *dp = dccp_sk(sk);
  45         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  46         struct rtable *rt;
  47         __be32 daddr, nexthop;
  48         int tmp;
  49         int err;
  50
  51         dp->dccps_role = DCCP_ROLE_CLIENT;
  52
  53         if (addr_len < sizeof(struct sockaddr_in))
  54                 return -EINVAL;
  55
  56         if (usin->sin_family != AF_INET)
  57                 return -EAFNOSUPPORT;
  58
  59         nexthop = daddr = usin->sin_addr.s_addr;
  60         if (inet->opt != NULL && inet->opt->srr) {
  61                 if (daddr == 0)
  62                         return -EINVAL;
  63                 nexthop = inet->opt->faddr;
  64         }
  65
  66         tmp = ip_route_connect(&rt, nexthop, inet->inet_saddr,
  67                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  68                                IPPROTO_DCCP,
  69                                inet->inet_sport, usin->sin_port, sk, 1);
  70         if (tmp < 0)
  71                 return tmp;
  72
  73         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  74                 ip_rt_put(rt);
  75                 return -ENETUNREACH;
  76         }
  77
  78         if (inet->opt == NULL || !inet->opt->srr)
  79                 daddr = rt->rt_dst;
  80
  81         if (inet->inet_saddr == 0)
  82                 inet->inet_saddr = rt->rt_src;
  83         inet->inet_rcv_saddr = inet->inet_saddr;
  84
  85         inet->inet_dport = usin->sin_port;
  86         inet->inet_daddr = daddr;
  87
  88         inet_csk(sk)->icsk_ext_hdr_len = 0;
  89         if (inet->opt != NULL)
  90                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
  91         /*
  92          * Socket identity is still unknown (sport may be zero).
  93          * However we set state to DCCP_REQUESTING and not releasing socket
  94          * lock select source port, enter ourselves into the hash tables and
  95          * complete initialization after this.
  96          */
  97         dccp_set_state(sk, DCCP_REQUESTING);
  98         err = inet_hash_connect(&dccp_death_row, sk);
  99         if (err != 0)
 100                 goto failure;
 101
 102         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->inet_sport,
 103                                 inet->inet_dport, sk);
 104         if (err != 0)
 105                 goto failure;
 106
 107         /* OK, now commit destination to socket.  */
 108         sk_setup_caps(sk, &rt->dst);
 109
 110         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 111                                                     inet->inet_daddr,
 112                                                     inet->inet_sport,
 113                                                     inet->inet_dport);
 114         inet->inet_id = dp->dccps_iss ^ jiffies;
 115
 116         err = dccp_connect(sk);
 117         rt = NULL;
 118         if (err != 0)
 119                 goto failure;
 120 out:
 121         return err;
 122 failure:
 123         /*
 124          * This unhashes the socket and releases the local port, if necessary.
 125          */
 126         dccp_set_state(sk, DCCP_CLOSED);
 127         ip_rt_put(rt);
 128         sk->sk_route_caps = 0;
 129         inet->inet_dport = 0;
 130         goto out;
 131 }
 132
 133 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 134
 135 /*
 136  * This routine does path mtu discovery as defined in RFC1191.
 137  */
 138 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 139                                           const struct iphdr *iph,
 140                                           u32 mtu)
 141 {
 142         struct dst_entry *dst;
 143         const struct inet_sock *inet = inet_sk(sk);
 144         const struct dccp_sock *dp = dccp_sk(sk);
 145
 146         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 147          * send out by Linux are always < 576bytes so they should go through
 148          * unfragmented).
 149          */
 150         if (sk->sk_state == DCCP_LISTEN)
 151                 return;
 152
 153         /* We don't check in the destentry if pmtu discovery is forbidden
 154          * on this route. We just assume that no packet_to_big packets
 155          * are send back when pmtu discovery is not active.
 156          * There is a small race when the user changes this flag in the
 157          * route, but I think that's acceptable.
 158          */
 159         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 160                 return;
 161
 162         dst->ops->update_pmtu(dst, mtu);
 163
 164         /* Something is about to be wrong... Remember soft error
 165          * for the case, if this connection will not able to recover.
 166          */
 167         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 168                 sk->sk_err_soft = EMSGSIZE;
 169
 170         mtu = dst_mtu(dst);
 171
 172         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 173             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 174                 dccp_sync_mss(sk, mtu);
 175
 176                 /*
 177                  * From RFC 4340, sec. 14.1:
 178                  *
 179                  *      DCCP-Sync packets are the best choice for upward
 180                  *      probing, since DCCP-Sync probes do not risk application
 181                  *      data loss.
 182                  */
 183                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 184         } /* else let the usual retransmit timer handle it */
 185 }
 186
 187 /*
 188  * This routine is called by the ICMP module when it gets some sort of error
 189  * condition. If err < 0 then the socket should be closed and the error
 190  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 191  * After adjustment header points to the first 8 bytes of the tcp header. We
 192  * need to find the appropriate port.
 193  *
 194  * The locking strategy used here is very "optimistic". When someone else
 195  * accesses the socket the ICMP is just dropped and for some paths there is no
 196  * check at all. A more general error queue to queue errors for later handling
 197  * is probably better.
 198  */
 199 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 200 {
 201         const struct iphdr *iph = (struct iphdr *)skb->data;
 202         const u8 offset = iph->ihl << 2;
 203         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
 204         struct dccp_sock *dp;
 205         struct inet_sock *inet;
 206         const int type = icmp_hdr(skb)->type;
 207         const int code = icmp_hdr(skb)->code;
 208         struct sock *sk;
 209         __u64 seq;
 210         int err;
 211         struct net *net = dev_net(skb->dev);
 212
 213         if (skb->len < offset + sizeof(*dh) ||
 214             skb->len < offset + __dccp_basic_hdr_len(dh)) {
 215                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 216                 return;
 217         }
 218
 219         sk = inet_lookup(net, &dccp_hashinfo,
 220                         iph->daddr, dh->dccph_dport,
 221                         iph->saddr, dh->dccph_sport, inet_iif(skb));
 222         if (sk == NULL) {
 223                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 224                 return;
 225         }
 226
 227         if (sk->sk_state == DCCP_TIME_WAIT) {
 228                 inet_twsk_put(inet_twsk(sk));
 229                 return;
 230         }
 231
 232         bh_lock_sock(sk);
 233         /* If too many ICMPs get dropped on busy
 234          * servers this needs to be solved differently.
 235          */
 236         if (sock_owned_by_user(sk))
 237                 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 238
 239         if (sk->sk_state == DCCP_CLOSED)
 240                 goto out;
 241
 242         dp = dccp_sk(sk);
 243         seq = dccp_hdr_seq(dh);
 244         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 245             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 246                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 247                 goto out;
 248         }
 249
 250         switch (type) {
 251         case ICMP_SOURCE_QUENCH:
 252                 /* Just silently ignore these. */
 253                 goto out;
 254         case ICMP_PARAMETERPROB:
 255                 err = EPROTO;
 256                 break;
 257         case ICMP_DEST_UNREACH:
 258                 if (code > NR_ICMP_UNREACH)
 259                         goto out;
 260
 261                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 262                         if (!sock_owned_by_user(sk))
 263                                 dccp_do_pmtu_discovery(sk, iph, info);
 264                         goto out;
 265                 }
 266
 267                 err = icmp_err_convert[code].errno;
 268                 break;
 269         case ICMP_TIME_EXCEEDED:
 270                 err = EHOSTUNREACH;
 271                 break;
 272         default:
 273                 goto out;
 274         }
 275
 276         switch (sk->sk_state) {
 277                 struct request_sock *req , **prev;
 278         case DCCP_LISTEN:
 279                 if (sock_owned_by_user(sk))
 280                         goto out;
 281                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 282                                           iph->daddr, iph->saddr);
 283                 if (!req)
 284                         goto out;
 285
 286                 /*
 287                  * ICMPs are not backlogged, hence we cannot get an established
 288                  * socket here.
 289                  */
 290                 WARN_ON(req->sk);
 291
 292                 if (seq != dccp_rsk(req)->dreq_iss) {
 293                         NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 294                         goto out;
 295                 }
 296                 /*
 297                  * Still in RESPOND, just remove it silently.
 298                  * There is no good way to pass the error to the newly
 299                  * created socket, and POSIX does not want network
 300                  * errors returned from accept().
 301                  */
 302                 inet_csk_reqsk_queue_drop(sk, req, prev);
 303                 goto out;
 304
 305         case DCCP_REQUESTING:
 306         case DCCP_RESPOND:
 307                 if (!sock_owned_by_user(sk)) {
 308                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 309                         sk->sk_err = err;
 310
 311                         sk->sk_error_report(sk);
 312
 313                         dccp_done(sk);
 314                 } else
 315                         sk->sk_err_soft = err;
 316                 goto out;
 317         }
 318
 319         /* If we've already connected we will keep trying
 320          * until we time out, or the user gives up.
 321          *
 322          * rfc1122 4.2.3.9 allows to consider as hard errors
 323          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 324          * but it is obsoleted by pmtu discovery).
 325          *
 326          * Note, that in modern internet, where routing is unreliable
 327          * and in each dark corner broken firewalls sit, sending random
 328          * errors ordered by their masters even this two messages finally lose
 329          * their original sense (even Linux sends invalid PORT_UNREACHs)
 330          *
 331          * Now we are in compliance with RFCs.
 332          *                                                      --ANK (980905)
 333          */
 334
 335         inet = inet_sk(sk);
 336         if (!sock_owned_by_user(sk) && inet->recverr) {
 337                 sk->sk_err = err;
 338                 sk->sk_error_report(sk);
 339         } else /* Only an error on timeout */
 340                 sk->sk_err_soft = err;
 341 out:
 342         bh_unlock_sock(sk);
 343         sock_put(sk);
 344 }
 345
 346 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 347                                       __be32 src, __be32 dst)
 348 {
 349         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 350 }
 351
 352 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 353 {
 354         const struct inet_sock *inet = inet_sk(sk);
 355         struct dccp_hdr *dh = dccp_hdr(skb);
 356
 357         dccp_csum_outgoing(skb);
 358         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 359                                                  inet->inet_saddr,
 360                                                  inet->inet_daddr);
 361 }
 362
 363 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 364
 365 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 366 {
 367         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 368                                            ip_hdr(skb)->saddr,
 369                                            dccp_hdr(skb)->dccph_dport,
 370                                            dccp_hdr(skb)->dccph_sport);
 371 }
 372
 373 /*
 374  * The three way handshake has completed - we got a valid ACK or DATAACK -
 375  * now create the new socket.
 376  *
 377  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 378  */
 379 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 380                                        struct request_sock *req,
 381                                        struct dst_entry *dst)
 382 {
 383         struct inet_request_sock *ireq;
 384         struct inet_sock *newinet;
 385         struct sock *newsk;
 386
 387         if (sk_acceptq_is_full(sk))
 388                 goto exit_overflow;
 389
 390         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 391                 goto exit;
 392
 393         newsk = dccp_create_openreq_child(sk, req, skb);
 394         if (newsk == NULL)
 395                 goto exit_nonewsk;
 396
 397         sk_setup_caps(newsk, dst);
 398
 399         newinet            = inet_sk(newsk);
 400         ireq               = inet_rsk(req);
 401         newinet->inet_daddr     = ireq->rmt_addr;
 402         newinet->inet_rcv_saddr = ireq->loc_addr;
 403         newinet->inet_saddr     = ireq->loc_addr;
 404         newinet->opt       = ireq->opt;
 405         ireq->opt          = NULL;
 406         newinet->mc_index  = inet_iif(skb);
 407         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 408         newinet->inet_id   = jiffies;
 409
 410         dccp_sync_mss(newsk, dst_mtu(dst));
 411
 412         if (__inet_inherit_port(sk, newsk) < 0) {
 413                 sock_put(newsk);
 414                 goto exit;
 415         }
 416         __inet_hash_nolisten(newsk, NULL);
 417
 418         return newsk;
 419
 420 exit_overflow:
 421         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 422 exit_nonewsk:
 423         dst_release(dst);
 424 exit:
 425         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 426         return NULL;
 427 }
 428
 429 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 430
 431 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 432 {
 433         const struct dccp_hdr *dh = dccp_hdr(skb);
 434         const struct iphdr *iph = ip_hdr(skb);
 435         struct sock *nsk;
 436         struct request_sock **prev;
 437         /* Find possible connection requests. */
 438         struct request_sock *req = inet_csk_search_req(sk, &prev,
 439                                                        dh->dccph_sport,
 440                                                        iph->saddr, iph->daddr);
 441         if (req != NULL)
 442                 return dccp_check_req(sk, skb, req, prev);
 443
 444         nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
 445                                       iph->saddr, dh->dccph_sport,
 446                                       iph->daddr, dh->dccph_dport,
 447                                       inet_iif(skb));
 448         if (nsk != NULL) {
 449                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 450                         bh_lock_sock(nsk);
 451                         return nsk;
 452                 }
 453                 inet_twsk_put(inet_twsk(nsk));
 454                 return NULL;
 455         }
 456
 457         return sk;
 458 }
 459
 460 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 461                                            struct sk_buff *skb)
 462 {
 463         struct rtable *rt;
 464         struct flowi fl = { .oif = skb_rtable(skb)->rt_iif,
 465                             .fl4_dst = ip_hdr(skb)->saddr,
 466                             .fl4_src = ip_hdr(skb)->daddr,
 467                             .fl4_tos = RT_CONN_FLAGS(sk),
 468                             .proto = sk->sk_protocol,
 469                             .fl_ip_sport = dccp_hdr(skb)->dccph_dport,
 470                             .fl_ip_dport = dccp_hdr(skb)->dccph_sport
 471                           };
 472
 473         security_skb_classify_flow(skb, &fl);
 474         if (ip_route_output_flow(net, &rt, &fl, sk, 0)) {
 475                 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 476                 return NULL;
 477         }
 478
 479         return &rt->dst;
 480 }
 481
 482 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 483                                  struct request_values *rv_unused)
 484 {
 485         int err = -1;
 486         struct sk_buff *skb;
 487         struct dst_entry *dst;
 488
 489         dst = inet_csk_route_req(sk, req);
 490         if (dst == NULL)
 491                 goto out;
 492
 493         skb = dccp_make_response(sk, dst, req);
 494         if (skb != NULL) {
 495                 const struct inet_request_sock *ireq = inet_rsk(req);
 496                 struct dccp_hdr *dh = dccp_hdr(skb);
 497
 498                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
 499                                                               ireq->rmt_addr);
 500                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 501                                             ireq->rmt_addr,
 502                                             ireq->opt);
 503                 err = net_xmit_eval(err);
 504         }
 505
 506 out:
 507         dst_release(dst);
 508         return err;
 509 }
 510
 511 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
 512 {
 513         int err;
 514         const struct iphdr *rxiph;
 515         struct sk_buff *skb;
 516         struct dst_entry *dst;
 517         struct net *net = dev_net(skb_dst(rxskb)->dev);
 518         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
 519
 520         /* Never send a reset in response to a reset. */
 521         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 522                 return;
 523
 524         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 525                 return;
 526
 527         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 528         if (dst == NULL)
 529                 return;
 530
 531         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 532         if (skb == NULL)
 533                 goto out;
 534
 535         rxiph = ip_hdr(rxskb);
 536         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 537                                                                  rxiph->daddr);
 538         skb_dst_set(skb, dst_clone(dst));
 539
 540         bh_lock_sock(ctl_sk);
 541         err = ip_build_and_send_pkt(skb, ctl_sk,
 542                                     rxiph->daddr, rxiph->saddr, NULL);
 543         bh_unlock_sock(ctl_sk);
 544
 545         if (net_xmit_eval(err) == 0) {
 546                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 547                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 548         }
 549 out:
 550          dst_release(dst);
 551 }
 552
 553 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 554 {
 555         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 556         kfree(inet_rsk(req)->opt);
 557 }
 558
 559 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 560         .family         = PF_INET,
 561         .obj_size       = sizeof(struct dccp_request_sock),
 562         .rtx_syn_ack    = dccp_v4_send_response,
 563         .send_ack       = dccp_reqsk_send_ack,
 564         .destructor     = dccp_v4_reqsk_destructor,
 565         .send_reset     = dccp_v4_ctl_send_reset,
 566 };
 567
 568 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 569 {
 570         struct inet_request_sock *ireq;
 571         struct request_sock *req;
 572         struct dccp_request_sock *dreq;
 573         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 574         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 575
 576         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 577         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 578                 return 0;       /* discard, don't send a reset here */
 579
 580         if (dccp_bad_service_code(sk, service)) {
 581                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 582                 goto drop;
 583         }
 584         /*
 585          * TW buckets are converted to open requests without
 586          * limitations, they conserve resources and peer is
 587          * evidently real one.
 588          */
 589         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 590         if (inet_csk_reqsk_queue_is_full(sk))
 591                 goto drop;
 592
 593         /*
 594          * Accept backlog is full. If we have already queued enough
 595          * of warm entries in syn queue, drop request. It is better than
 596          * clogging syn queue with openreqs with exponentially increasing
 597          * timeout.
 598          */
 599         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 600                 goto drop;
 601
 602         req = inet_reqsk_alloc(&dccp_request_sock_ops);
 603         if (req == NULL)
 604                 goto drop;
 605
 606         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 607                 goto drop_and_free;
 608
 609         dreq = dccp_rsk(req);
 610         if (dccp_parse_options(sk, dreq, skb))
 611                 goto drop_and_free;
 612
 613         if (security_inet_conn_request(sk, skb, req))
 614                 goto drop_and_free;
 615
 616         ireq = inet_rsk(req);
 617         ireq->loc_addr = ip_hdr(skb)->daddr;
 618         ireq->rmt_addr = ip_hdr(skb)->saddr;
 619
 620         /*
 621          * Step 3: Process LISTEN state
 622          *
 623          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 624          *
 625          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 626          * dccp_create_openreq_child.
 627          */
 628         dreq->dreq_isr     = dcb->dccpd_seq;
 629         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 630         dreq->dreq_service = service;
 631
 632         if (dccp_v4_send_response(sk, req, NULL))
 633                 goto drop_and_free;
 634
 635         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 636         return 0;
 637
 638 drop_and_free:
 639         reqsk_free(req);
 640 drop:
 641         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 642         return -1;
 643 }
 644
 645 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 646
 647 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 648 {
 649         struct dccp_hdr *dh = dccp_hdr(skb);
 650
 651         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 652                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 653                         goto reset;
 654                 return 0;
 655         }
 656
 657         /*
 658          *  Step 3: Process LISTEN state
 659          *       If P.type == Request or P contains a valid Init Cookie option,
 660          *            (* Must scan the packet's options to check for Init
 661          *               Cookies.  Only Init Cookies are processed here,
 662          *               however; other options are processed in Step 8.  This
 663          *               scan need only be performed if the endpoint uses Init
 664          *               Cookies *)
 665          *            (* Generate a new socket and switch to that socket *)
 666          *            Set S := new socket for this port pair
 667          *            S.state = RESPOND
 668          *            Choose S.ISS (initial seqno) or set from Init Cookies
 669          *            Initialize S.GAR := S.ISS
 670          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 671          *            Continue with S.state == RESPOND
 672          *            (* A Response packet will be generated in Step 11 *)
 673          *       Otherwise,
 674          *            Generate Reset(No Connection) unless P.type == Reset
 675          *            Drop packet and return
 676          *
 677          * NOTE: the check for the packet types is done in
 678          *       dccp_rcv_state_process
 679          */
 680         if (sk->sk_state == DCCP_LISTEN) {
 681                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 682
 683                 if (nsk == NULL)
 684                         goto discard;
 685
 686                 if (nsk != sk) {
 687                         if (dccp_child_process(sk, nsk, skb))
 688                                 goto reset;
 689                         return 0;
 690                 }
 691         }
 692
 693         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 694                 goto reset;
 695         return 0;
 696
 697 reset:
 698         dccp_v4_ctl_send_reset(sk, skb);
 699 discard:
 700         kfree_skb(skb);
 701         return 0;
 702 }
 703
 704 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 705
 706 /**
 707  *      dccp_invalid_packet  -  check for malformed packets
 708  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 709  *      Packets that fail these checks are ignored and do not receive Resets.
 710  */
 711 int dccp_invalid_packet(struct sk_buff *skb)
 712 {
 713         const struct dccp_hdr *dh;
 714         unsigned int cscov;
 715
 716         if (skb->pkt_type != PACKET_HOST)
 717                 return 1;
 718
 719         /* If the packet is shorter than 12 bytes, drop packet and return */
 720         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 721                 DCCP_WARN("pskb_may_pull failed\n");
 722                 return 1;
 723         }
 724
 725         dh = dccp_hdr(skb);
 726
 727         /* If P.type is not understood, drop packet and return */
 728         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 729                 DCCP_WARN("invalid packet type\n");
 730                 return 1;
 731         }
 732
 733         /*
 734          * If P.Data Offset is too small for packet type, drop packet and return
 735          */
 736         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 737                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
 738                 return 1;
 739         }
 740         /*
 741          * If P.Data Offset is too too large for packet, drop packet and return
 742          */
 743         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 744                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
 745                 return 1;
 746         }
 747
 748         /*
 749          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 750          * has short sequence numbers), drop packet and return
 751          */
 752         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 753             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 754                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 755                           dccp_packet_name(dh->dccph_type));
 756                 return 1;
 757         }
 758
 759         /*
 760          * If P.CsCov is too large for the packet size, drop packet and return.
 761          * This must come _before_ checksumming (not as RFC 4340 suggests).
 762          */
 763         cscov = dccp_csum_coverage(skb);
 764         if (cscov > skb->len) {
 765                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 766                           dh->dccph_cscov, skb->len);
 767                 return 1;
 768         }
 769
 770         /* If header checksum is incorrect, drop packet and return.
 771          * (This step is completed in the AF-dependent functions.) */
 772         skb->csum = skb_checksum(skb, 0, cscov, 0);
 773
 774         return 0;
 775 }
 776
 777 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 778
 779 /* this is called when real data arrives */
 780 static int dccp_v4_rcv(struct sk_buff *skb)
 781 {
 782         const struct dccp_hdr *dh;
 783         const struct iphdr *iph;
 784         struct sock *sk;
 785         int min_cov;
 786
 787         /* Step 1: Check header basics */
 788
 789         if (dccp_invalid_packet(skb))
 790                 goto discard_it;
 791
 792         iph = ip_hdr(skb);
 793         /* Step 1: If header checksum is incorrect, drop packet and return */
 794         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 795                 DCCP_WARN("dropped packet with invalid checksum\n");
 796                 goto discard_it;
 797         }
 798
 799         dh = dccp_hdr(skb);
 800
 801         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 802         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 803
 804         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 805                       dccp_packet_name(dh->dccph_type),
 806                       &iph->saddr, ntohs(dh->dccph_sport),
 807                       &iph->daddr, ntohs(dh->dccph_dport),
 808                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 809
 810         if (dccp_packet_without_ack(skb)) {
 811                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 812                 dccp_pr_debug_cat("\n");
 813         } else {
 814                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 815                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 816                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 817         }
 818
 819         /* Step 2:
 820          *      Look up flow ID in table and get corresponding socket */
 821         sk = __inet_lookup_skb(&dccp_hashinfo, skb,
 822                                dh->dccph_sport, dh->dccph_dport);
 823         /*
 824          * Step 2:
 825          *      If no socket ...
 826          */
 827         if (sk == NULL) {
 828                 dccp_pr_debug("failed to look up flow ID in table and "
 829                               "get corresponding socket\n");
 830                 goto no_dccp_socket;
 831         }
 832
 833         /*
 834          * Step 2:
 835          *      ... or S.state == TIMEWAIT,
 836          *              Generate Reset(No Connection) unless P.type == Reset
 837          *              Drop packet and return
 838          */
 839         if (sk->sk_state == DCCP_TIME_WAIT) {
 840                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 841                 inet_twsk_put(inet_twsk(sk));
 842                 goto no_dccp_socket;
 843         }
 844
 845         /*
 846          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 847          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 848          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 849          */
 850         min_cov = dccp_sk(sk)->dccps_pcrlen;
 851         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 852                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 853                               dh->dccph_cscov, min_cov);
 854                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 855                  *         options (Section 11.7) with Drop Code 0, Protocol
 856                  *         Constraints."                                     */
 857                 goto discard_and_relse;
 858         }
 859
 860         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 861                 goto discard_and_relse;
 862         nf_reset(skb);
 863
 864         return sk_receive_skb(sk, skb, 1);
 865
 866 no_dccp_socket:
 867         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 868                 goto discard_it;
 869         /*
 870          * Step 2:
 871          *      If no socket ...
 872          *              Generate Reset(No Connection) unless P.type == Reset
 873          *              Drop packet and return
 874          */
 875         if (dh->dccph_type != DCCP_PKT_RESET) {
 876                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 877                                         DCCP_RESET_CODE_NO_CONNECTION;
 878                 dccp_v4_ctl_send_reset(sk, skb);
 879         }
 880
 881 discard_it:
 882         kfree_skb(skb);
 883         return 0;
 884
 885 discard_and_relse:
 886         sock_put(sk);
 887         goto discard_it;
 888 }
 889
 890 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 891         .queue_xmit        = ip_queue_xmit,
 892         .send_check        = dccp_v4_send_check,
 893         .rebuild_header    = inet_sk_rebuild_header,
 894         .conn_request      = dccp_v4_conn_request,
 895         .syn_recv_sock     = dccp_v4_request_recv_sock,
 896         .net_header_len    = sizeof(struct iphdr),
 897         .setsockopt        = ip_setsockopt,
 898         .getsockopt        = ip_getsockopt,
 899         .addr2sockaddr     = inet_csk_addr2sockaddr,
 900         .sockaddr_len      = sizeof(struct sockaddr_in),
 901         .bind_conflict     = inet_csk_bind_conflict,
 902 #ifdef CONFIG_COMPAT
 903         .compat_setsockopt = compat_ip_setsockopt,
 904         .compat_getsockopt = compat_ip_getsockopt,
 905 #endif
 906 };
 907
 908 static int dccp_v4_init_sock(struct sock *sk)
 909 {
 910         static __u8 dccp_v4_ctl_sock_initialized;
 911         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 912
 913         if (err == 0) {
 914                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 915                         dccp_v4_ctl_sock_initialized = 1;
 916                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 917         }
 918
 919         return err;
 920 }
 921
 922 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 923         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 924 };
 925
 926 static struct proto dccp_v4_prot = {
 927         .name                   = "DCCP",
 928         .owner                  = THIS_MODULE,
 929         .close                  = dccp_close,
 930         .connect                = dccp_v4_connect,
 931         .disconnect             = dccp_disconnect,
 932         .ioctl                  = dccp_ioctl,
 933         .init                   = dccp_v4_init_sock,
 934         .setsockopt             = dccp_setsockopt,
 935         .getsockopt             = dccp_getsockopt,
 936         .sendmsg                = dccp_sendmsg,
 937         .recvmsg                = dccp_recvmsg,
 938         .backlog_rcv            = dccp_v4_do_rcv,
 939         .hash                   = inet_hash,
 940         .unhash                 = inet_unhash,
 941         .accept                 = inet_csk_accept,
 942         .get_port               = inet_csk_get_port,
 943         .shutdown               = dccp_shutdown,
 944         .destroy                = dccp_destroy_sock,
 945         .orphan_count           = &dccp_orphan_count,
 946         .max_header             = MAX_DCCP_HEADER,
 947         .obj_size               = sizeof(struct dccp_sock),
 948         .slab_flags             = SLAB_DESTROY_BY_RCU,
 949         .rsk_prot               = &dccp_request_sock_ops,
 950         .twsk_prot              = &dccp_timewait_sock_ops,
 951         .h.hashinfo             = &dccp_hashinfo,
 952 #ifdef CONFIG_COMPAT
 953         .compat_setsockopt      = compat_dccp_setsockopt,
 954         .compat_getsockopt      = compat_dccp_getsockopt,
 955 #endif
 956 };
 957
 958 static const struct net_protocol dccp_v4_protocol = {
 959         .handler        = dccp_v4_rcv,
 960         .err_handler    = dccp_v4_err,
 961         .no_policy      = 1,
 962         .netns_ok       = 1,
 963 };
 964
 965 static const struct proto_ops inet_dccp_ops = {
 966         .family            = PF_INET,
 967         .owner             = THIS_MODULE,
 968         .release           = inet_release,
 969         .bind              = inet_bind,
 970         .connect           = inet_stream_connect,
 971         .socketpair        = sock_no_socketpair,
 972         .accept            = inet_accept,
 973         .getname           = inet_getname,
 974         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 975         .poll              = dccp_poll,
 976         .ioctl             = inet_ioctl,
 977         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 978         .listen            = inet_dccp_listen,
 979         .shutdown          = inet_shutdown,
 980         .setsockopt        = sock_common_setsockopt,
 981         .getsockopt        = sock_common_getsockopt,
 982         .sendmsg           = inet_sendmsg,
 983         .recvmsg           = sock_common_recvmsg,
 984         .mmap              = sock_no_mmap,
 985         .sendpage          = sock_no_sendpage,
 986 #ifdef CONFIG_COMPAT
 987         .compat_setsockopt = compat_sock_common_setsockopt,
 988         .compat_getsockopt = compat_sock_common_getsockopt,
 989 #endif
 990 };
 991
 992 static struct inet_protosw dccp_v4_protosw = {
 993         .type           = SOCK_DCCP,
 994         .protocol       = IPPROTO_DCCP,
 995         .prot           = &dccp_v4_prot,
 996         .ops            = &inet_dccp_ops,
 997         .no_check       = 0,
 998         .flags          = INET_PROTOSW_ICSK,
 999 };
1000
1001 static int __net_init dccp_v4_init_net(struct net *net)
1002 {
1003         if (dccp_hashinfo.bhash == NULL)
1004                 return -ESOCKTNOSUPPORT;
1005
1006         return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1007                                     SOCK_DCCP, IPPROTO_DCCP, net);
1008 }
1009
1010 static void __net_exit dccp_v4_exit_net(struct net *net)
1011 {
1012         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1013 }
1014
1015 static struct pernet_operations dccp_v4_ops = {
1016         .init   = dccp_v4_init_net,
1017         .exit   = dccp_v4_exit_net,
1018 };
1019
1020 static int __init dccp_v4_init(void)
1021 {
1022         int err = proto_register(&dccp_v4_prot, 1);
1023
1024         if (err != 0)
1025                 goto out;
1026
1027         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1028         if (err != 0)
1029                 goto out_proto_unregister;
1030
1031         inet_register_protosw(&dccp_v4_protosw);
1032
1033         err = register_pernet_subsys(&dccp_v4_ops);
1034         if (err)
1035                 goto out_destroy_ctl_sock;
1036 out:
1037         return err;
1038 out_destroy_ctl_sock:
1039         inet_unregister_protosw(&dccp_v4_protosw);
1040         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1041 out_proto_unregister:
1042         proto_unregister(&dccp_v4_prot);
1043         goto out;
1044 }
1045
1046 static void __exit dccp_v4_exit(void)
1047 {
1048         unregister_pernet_subsys(&dccp_v4_ops);
1049         inet_unregister_protosw(&dccp_v4_protosw);
1050         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1051         proto_unregister(&dccp_v4_prot);
1052 }
1053
1054 module_init(dccp_v4_init);
1055 module_exit(dccp_v4_exit);
1056
1057 /*
1058  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1059  * values directly, Also cover the case where the protocol is not specified,
1060  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1061  */
1062 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1063 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1064 MODULE_LICENSE("GPL");
1065 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1066 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");