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/module.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/random.h>
  18
  19 #include <net/icmp.h>
  20 #include <net/inet_common.h>
  21 #include <net/inet_hashtables.h>
  22 #include <net/inet_sock.h>
  23 #include <net/protocol.h>
  24 #include <net/sock.h>
  25 #include <net/timewait_sock.h>
  26 #include <net/tcp_states.h>
  27 #include <net/xfrm.h>
  28
  29 #include "ackvec.h"
  30 #include "ccid.h"
  31 #include "dccp.h"
  32 #include "feat.h"
  33
  34 /*
  35  * The per-net dccp.v4_ctl_sk socket is used for responding to
  36  * the Out-of-the-blue (OOTB) packets. A control sock will be created
  37  * for this socket at the initialization time.
  38  */
  39
  40 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  41 {
  42         struct inet_sock *inet = inet_sk(sk);
  43         struct dccp_sock *dp = dccp_sk(sk);
  44         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  45         struct rtable *rt;
  46         __be32 daddr, nexthop;
  47         int tmp;
  48         int err;
  49
  50         dp->dccps_role = DCCP_ROLE_CLIENT;
  51
  52         if (addr_len < sizeof(struct sockaddr_in))
  53                 return -EINVAL;
  54
  55         if (usin->sin_family != AF_INET)
  56                 return -EAFNOSUPPORT;
  57
  58         nexthop = daddr = usin->sin_addr.s_addr;
  59         if (inet->opt != NULL && inet->opt->srr) {
  60                 if (daddr == 0)
  61                         return -EINVAL;
  62                 nexthop = inet->opt->faddr;
  63         }
  64
  65         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
  66                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  67                                IPPROTO_DCCP,
  68                                inet->sport, usin->sin_port, sk, 1);
  69         if (tmp < 0)
  70                 return tmp;
  71
  72         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  73                 ip_rt_put(rt);
  74                 return -ENETUNREACH;
  75         }
  76
  77         if (inet->opt == NULL || !inet->opt->srr)
  78                 daddr = rt->rt_dst;
  79
  80         if (inet->saddr == 0)
  81                 inet->saddr = rt->rt_src;
  82         inet->rcv_saddr = inet->saddr;
  83
  84         inet->dport = usin->sin_port;
  85         inet->daddr = daddr;
  86
  87         inet_csk(sk)->icsk_ext_hdr_len = 0;
  88         if (inet->opt != NULL)
  89                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
  90         /*
  91          * Socket identity is still unknown (sport may be zero).
  92          * However we set state to DCCP_REQUESTING and not releasing socket
  93          * lock select source port, enter ourselves into the hash tables and
  94          * complete initialization after this.
  95          */
  96         dccp_set_state(sk, DCCP_REQUESTING);
  97         err = inet_hash_connect(&dccp_death_row, sk);
  98         if (err != 0)
  99                 goto failure;
 100
 101         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
 102                                 sk);
 103         if (err != 0)
 104                 goto failure;
 105
 106         /* OK, now commit destination to socket.  */
 107         sk_setup_caps(sk, &rt->u.dst);
 108
 109         dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, inet->daddr,
 110                                                     inet->sport, inet->dport);
 111         inet->id = dp->dccps_iss ^ jiffies;
 112
 113         err = dccp_connect(sk);
 114         rt = NULL;
 115         if (err != 0)
 116                 goto failure;
 117 out:
 118         return err;
 119 failure:
 120         /*
 121          * This unhashes the socket and releases the local port, if necessary.
 122          */
 123         dccp_set_state(sk, DCCP_CLOSED);
 124         ip_rt_put(rt);
 125         sk->sk_route_caps = 0;
 126         inet->dport = 0;
 127         goto out;
 128 }
 129
 130 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 131
 132 /*
 133  * This routine does path mtu discovery as defined in RFC1191.
 134  */
 135 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 136                                           const struct iphdr *iph,
 137                                           u32 mtu)
 138 {
 139         struct dst_entry *dst;
 140         const struct inet_sock *inet = inet_sk(sk);
 141         const struct dccp_sock *dp = dccp_sk(sk);
 142
 143         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 144          * send out by Linux are always < 576bytes so they should go through
 145          * unfragmented).
 146          */
 147         if (sk->sk_state == DCCP_LISTEN)
 148                 return;
 149
 150         /* We don't check in the destentry if pmtu discovery is forbidden
 151          * on this route. We just assume that no packet_to_big packets
 152          * are send back when pmtu discovery is not active.
 153          * There is a small race when the user changes this flag in the
 154          * route, but I think that's acceptable.
 155          */
 156         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 157                 return;
 158
 159         dst->ops->update_pmtu(dst, mtu);
 160
 161         /* Something is about to be wrong... Remember soft error
 162          * for the case, if this connection will not able to recover.
 163          */
 164         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 165                 sk->sk_err_soft = EMSGSIZE;
 166
 167         mtu = dst_mtu(dst);
 168
 169         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 170             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 171                 dccp_sync_mss(sk, mtu);
 172
 173                 /*
 174                  * From RFC 4340, sec. 14.1:
 175                  *
 176                  *      DCCP-Sync packets are the best choice for upward
 177                  *      probing, since DCCP-Sync probes do not risk application
 178                  *      data loss.
 179                  */
 180                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 181         } /* else let the usual retransmit timer handle it */
 182 }
 183
 184 /*
 185  * This routine is called by the ICMP module when it gets some sort of error
 186  * condition. If err < 0 then the socket should be closed and the error
 187  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 188  * After adjustment header points to the first 8 bytes of the tcp header. We
 189  * need to find the appropriate port.
 190  *
 191  * The locking strategy used here is very "optimistic". When someone else
 192  * accesses the socket the ICMP is just dropped and for some paths there is no
 193  * check at all. A more general error queue to queue errors for later handling
 194  * is probably better.
 195  */
 196 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 197 {
 198         const struct iphdr *iph = (struct iphdr *)skb->data;
 199         const u8 offset = iph->ihl << 2;
 200         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
 201         struct dccp_sock *dp;
 202         struct inet_sock *inet;
 203         const int type = icmp_hdr(skb)->type;
 204         const int code = icmp_hdr(skb)->code;
 205         struct sock *sk;
 206         __u64 seq;
 207         int err;
 208         struct net *net = dev_net(skb->dev);
 209
 210         if (skb->len < offset + sizeof(*dh) ||
 211             skb->len < offset + __dccp_basic_hdr_len(dh)) {
 212                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 213                 return;
 214         }
 215
 216         sk = inet_lookup(net, &dccp_hashinfo,
 217                         iph->daddr, dh->dccph_dport,
 218                         iph->saddr, dh->dccph_sport, inet_iif(skb));
 219         if (sk == NULL) {
 220                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 221                 return;
 222         }
 223
 224         if (sk->sk_state == DCCP_TIME_WAIT) {
 225                 inet_twsk_put(inet_twsk(sk));
 226                 return;
 227         }
 228
 229         bh_lock_sock(sk);
 230         /* If too many ICMPs get dropped on busy
 231          * servers this needs to be solved differently.
 232          */
 233         if (sock_owned_by_user(sk))
 234                 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 235
 236         if (sk->sk_state == DCCP_CLOSED)
 237                 goto out;
 238
 239         dp = dccp_sk(sk);
 240         seq = dccp_hdr_seq(dh);
 241         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 242             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 243                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 244                 goto out;
 245         }
 246
 247         switch (type) {
 248         case ICMP_SOURCE_QUENCH:
 249                 /* Just silently ignore these. */
 250                 goto out;
 251         case ICMP_PARAMETERPROB:
 252                 err = EPROTO;
 253                 break;
 254         case ICMP_DEST_UNREACH:
 255                 if (code > NR_ICMP_UNREACH)
 256                         goto out;
 257
 258                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 259                         if (!sock_owned_by_user(sk))
 260                                 dccp_do_pmtu_discovery(sk, iph, info);
 261                         goto out;
 262                 }
 263
 264                 err = icmp_err_convert[code].errno;
 265                 break;
 266         case ICMP_TIME_EXCEEDED:
 267                 err = EHOSTUNREACH;
 268                 break;
 269         default:
 270                 goto out;
 271         }
 272
 273         switch (sk->sk_state) {
 274                 struct request_sock *req , **prev;
 275         case DCCP_LISTEN:
 276                 if (sock_owned_by_user(sk))
 277                         goto out;
 278                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 279                                           iph->daddr, iph->saddr);
 280                 if (!req)
 281                         goto out;
 282
 283                 /*
 284                  * ICMPs are not backlogged, hence we cannot get an established
 285                  * socket here.
 286                  */
 287                 WARN_ON(req->sk);
 288
 289                 if (seq != dccp_rsk(req)->dreq_iss) {
 290                         NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 291                         goto out;
 292                 }
 293                 /*
 294                  * Still in RESPOND, just remove it silently.
 295                  * There is no good way to pass the error to the newly
 296                  * created socket, and POSIX does not want network
 297                  * errors returned from accept().
 298                  */
 299                 inet_csk_reqsk_queue_drop(sk, req, prev);
 300                 goto out;
 301
 302         case DCCP_REQUESTING:
 303         case DCCP_RESPOND:
 304                 if (!sock_owned_by_user(sk)) {
 305                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 306                         sk->sk_err = err;
 307
 308                         sk->sk_error_report(sk);
 309
 310                         dccp_done(sk);
 311                 } else
 312                         sk->sk_err_soft = err;
 313                 goto out;
 314         }
 315
 316         /* If we've already connected we will keep trying
 317          * until we time out, or the user gives up.
 318          *
 319          * rfc1122 4.2.3.9 allows to consider as hard errors
 320          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 321          * but it is obsoleted by pmtu discovery).
 322          *
 323          * Note, that in modern internet, where routing is unreliable
 324          * and in each dark corner broken firewalls sit, sending random
 325          * errors ordered by their masters even this two messages finally lose
 326          * their original sense (even Linux sends invalid PORT_UNREACHs)
 327          *
 328          * Now we are in compliance with RFCs.
 329          *                                                      --ANK (980905)
 330          */
 331
 332         inet = inet_sk(sk);
 333         if (!sock_owned_by_user(sk) && inet->recverr) {
 334                 sk->sk_err = err;
 335                 sk->sk_error_report(sk);
 336         } else /* Only an error on timeout */
 337                 sk->sk_err_soft = err;
 338 out:
 339         bh_unlock_sock(sk);
 340         sock_put(sk);
 341 }
 342
 343 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 344                                       __be32 src, __be32 dst)
 345 {
 346         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 347 }
 348
 349 void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
 350 {
 351         const struct inet_sock *inet = inet_sk(sk);
 352         struct dccp_hdr *dh = dccp_hdr(skb);
 353
 354         dccp_csum_outgoing(skb);
 355         dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
 356 }
 357
 358 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 359
 360 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 361 {
 362         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 363                                            ip_hdr(skb)->saddr,
 364                                            dccp_hdr(skb)->dccph_dport,
 365                                            dccp_hdr(skb)->dccph_sport);
 366 }
 367
 368 /*
 369  * The three way handshake has completed - we got a valid ACK or DATAACK -
 370  * now create the new socket.
 371  *
 372  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 373  */
 374 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 375                                        struct request_sock *req,
 376                                        struct dst_entry *dst)
 377 {
 378         struct inet_request_sock *ireq;
 379         struct inet_sock *newinet;
 380         struct sock *newsk;
 381
 382         if (sk_acceptq_is_full(sk))
 383                 goto exit_overflow;
 384
 385         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 386                 goto exit;
 387
 388         newsk = dccp_create_openreq_child(sk, req, skb);
 389         if (newsk == NULL)
 390                 goto exit;
 391
 392         sk_setup_caps(newsk, dst);
 393
 394         newinet            = inet_sk(newsk);
 395         ireq               = inet_rsk(req);
 396         newinet->daddr     = ireq->rmt_addr;
 397         newinet->rcv_saddr = ireq->loc_addr;
 398         newinet->saddr     = ireq->loc_addr;
 399         newinet->opt       = ireq->opt;
 400         ireq->opt          = NULL;
 401         newinet->mc_index  = inet_iif(skb);
 402         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 403         newinet->id        = jiffies;
 404
 405         dccp_sync_mss(newsk, dst_mtu(dst));
 406
 407         __inet_hash_nolisten(newsk);
 408         __inet_inherit_port(sk, newsk);
 409
 410         return newsk;
 411
 412 exit_overflow:
 413         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 414 exit:
 415         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 416         dst_release(dst);
 417         return NULL;
 418 }
 419
 420 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 421
 422 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 423 {
 424         const struct dccp_hdr *dh = dccp_hdr(skb);
 425         const struct iphdr *iph = ip_hdr(skb);
 426         struct sock *nsk;
 427         struct request_sock **prev;
 428         /* Find possible connection requests. */
 429         struct request_sock *req = inet_csk_search_req(sk, &prev,
 430                                                        dh->dccph_sport,
 431                                                        iph->saddr, iph->daddr);
 432         if (req != NULL)
 433                 return dccp_check_req(sk, skb, req, prev);
 434
 435         nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
 436                                       iph->saddr, dh->dccph_sport,
 437                                       iph->daddr, dh->dccph_dport,
 438                                       inet_iif(skb));
 439         if (nsk != NULL) {
 440                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 441                         bh_lock_sock(nsk);
 442                         return nsk;
 443                 }
 444                 inet_twsk_put(inet_twsk(nsk));
 445                 return NULL;
 446         }
 447
 448         return sk;
 449 }
 450
 451 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 452                                            struct sk_buff *skb)
 453 {
 454         struct rtable *rt;
 455         struct flowi fl = { .oif = skb_rtable(skb)->rt_iif,
 456                             .nl_u = { .ip4_u =
 457                                       { .daddr = ip_hdr(skb)->saddr,
 458                                         .saddr = ip_hdr(skb)->daddr,
 459                                         .tos = RT_CONN_FLAGS(sk) } },
 460                             .proto = sk->sk_protocol,
 461                             .uli_u = { .ports =
 462                                        { .sport = dccp_hdr(skb)->dccph_dport,
 463                                          .dport = dccp_hdr(skb)->dccph_sport }
 464                                      }
 465                           };
 466
 467         security_skb_classify_flow(skb, &fl);
 468         if (ip_route_output_flow(net, &rt, &fl, sk, 0)) {
 469                 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 470                 return NULL;
 471         }
 472
 473         return &rt->u.dst;
 474 }
 475
 476 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
 477 {
 478         int err = -1;
 479         struct sk_buff *skb;
 480         struct dst_entry *dst;
 481
 482         dst = inet_csk_route_req(sk, req);
 483         if (dst == NULL)
 484                 goto out;
 485
 486         skb = dccp_make_response(sk, dst, req);
 487         if (skb != NULL) {
 488                 const struct inet_request_sock *ireq = inet_rsk(req);
 489                 struct dccp_hdr *dh = dccp_hdr(skb);
 490
 491                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
 492                                                               ireq->rmt_addr);
 493                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 494                                             ireq->rmt_addr,
 495                                             ireq->opt);
 496                 err = net_xmit_eval(err);
 497         }
 498
 499 out:
 500         dst_release(dst);
 501         return err;
 502 }
 503
 504 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
 505 {
 506         int err;
 507         const struct iphdr *rxiph;
 508         struct sk_buff *skb;
 509         struct dst_entry *dst;
 510         struct net *net = dev_net(skb_dst(rxskb)->dev);
 511         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
 512
 513         /* Never send a reset in response to a reset. */
 514         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 515                 return;
 516
 517         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 518                 return;
 519
 520         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 521         if (dst == NULL)
 522                 return;
 523
 524         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 525         if (skb == NULL)
 526                 goto out;
 527
 528         rxiph = ip_hdr(rxskb);
 529         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 530                                                                  rxiph->daddr);
 531         skb_dst_set(skb, dst_clone(dst));
 532
 533         bh_lock_sock(ctl_sk);
 534         err = ip_build_and_send_pkt(skb, ctl_sk,
 535                                     rxiph->daddr, rxiph->saddr, NULL);
 536         bh_unlock_sock(ctl_sk);
 537
 538         if (net_xmit_eval(err) == 0) {
 539                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 540                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 541         }
 542 out:
 543          dst_release(dst);
 544 }
 545
 546 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 547 {
 548         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 549         kfree(inet_rsk(req)->opt);
 550 }
 551
 552 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 553         .family         = PF_INET,
 554         .obj_size       = sizeof(struct dccp_request_sock),
 555         .rtx_syn_ack    = dccp_v4_send_response,
 556         .send_ack       = dccp_reqsk_send_ack,
 557         .destructor     = dccp_v4_reqsk_destructor,
 558         .send_reset     = dccp_v4_ctl_send_reset,
 559 };
 560
 561 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 562 {
 563         struct inet_request_sock *ireq;
 564         struct request_sock *req;
 565         struct dccp_request_sock *dreq;
 566         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 567         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 568
 569         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 570         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 571                 return 0;       /* discard, don't send a reset here */
 572
 573         if (dccp_bad_service_code(sk, service)) {
 574                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 575                 goto drop;
 576         }
 577         /*
 578          * TW buckets are converted to open requests without
 579          * limitations, they conserve resources and peer is
 580          * evidently real one.
 581          */
 582         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 583         if (inet_csk_reqsk_queue_is_full(sk))
 584                 goto drop;
 585
 586         /*
 587          * Accept backlog is full. If we have already queued enough
 588          * of warm entries in syn queue, drop request. It is better than
 589          * clogging syn queue with openreqs with exponentially increasing
 590          * timeout.
 591          */
 592         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 593                 goto drop;
 594
 595         req = inet_reqsk_alloc(&dccp_request_sock_ops);
 596         if (req == NULL)
 597                 goto drop;
 598
 599         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 600                 goto drop_and_free;
 601
 602         dreq = dccp_rsk(req);
 603         if (dccp_parse_options(sk, dreq, skb))
 604                 goto drop_and_free;
 605
 606         if (security_inet_conn_request(sk, skb, req))
 607                 goto drop_and_free;
 608
 609         ireq = inet_rsk(req);
 610         ireq->loc_addr = ip_hdr(skb)->daddr;
 611         ireq->rmt_addr = ip_hdr(skb)->saddr;
 612
 613         /*
 614          * Step 3: Process LISTEN state
 615          *
 616          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 617          *
 618          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 619          * dccp_create_openreq_child.
 620          */
 621         dreq->dreq_isr     = dcb->dccpd_seq;
 622         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 623         dreq->dreq_service = service;
 624
 625         if (dccp_v4_send_response(sk, req))
 626                 goto drop_and_free;
 627
 628         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 629         return 0;
 630
 631 drop_and_free:
 632         reqsk_free(req);
 633 drop:
 634         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 635         return -1;
 636 }
 637
 638 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 639
 640 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 641 {
 642         struct dccp_hdr *dh = dccp_hdr(skb);
 643
 644         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 645                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 646                         goto reset;
 647                 return 0;
 648         }
 649
 650         /*
 651          *  Step 3: Process LISTEN state
 652          *       If P.type == Request or P contains a valid Init Cookie option,
 653          *            (* Must scan the packet's options to check for Init
 654          *               Cookies.  Only Init Cookies are processed here,
 655          *               however; other options are processed in Step 8.  This
 656          *               scan need only be performed if the endpoint uses Init
 657          *               Cookies *)
 658          *            (* Generate a new socket and switch to that socket *)
 659          *            Set S := new socket for this port pair
 660          *            S.state = RESPOND
 661          *            Choose S.ISS (initial seqno) or set from Init Cookies
 662          *            Initialize S.GAR := S.ISS
 663          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 664          *            Continue with S.state == RESPOND
 665          *            (* A Response packet will be generated in Step 11 *)
 666          *       Otherwise,
 667          *            Generate Reset(No Connection) unless P.type == Reset
 668          *            Drop packet and return
 669          *
 670          * NOTE: the check for the packet types is done in
 671          *       dccp_rcv_state_process
 672          */
 673         if (sk->sk_state == DCCP_LISTEN) {
 674                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 675
 676                 if (nsk == NULL)
 677                         goto discard;
 678
 679                 if (nsk != sk) {
 680                         if (dccp_child_process(sk, nsk, skb))
 681                                 goto reset;
 682                         return 0;
 683                 }
 684         }
 685
 686         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 687                 goto reset;
 688         return 0;
 689
 690 reset:
 691         dccp_v4_ctl_send_reset(sk, skb);
 692 discard:
 693         kfree_skb(skb);
 694         return 0;
 695 }
 696
 697 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 698
 699 /**
 700  *      dccp_invalid_packet  -  check for malformed packets
 701  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 702  *      Packets that fail these checks are ignored and do not receive Resets.
 703  */
 704 int dccp_invalid_packet(struct sk_buff *skb)
 705 {
 706         const struct dccp_hdr *dh;
 707         unsigned int cscov;
 708
 709         if (skb->pkt_type != PACKET_HOST)
 710                 return 1;
 711
 712         /* If the packet is shorter than 12 bytes, drop packet and return */
 713         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 714                 DCCP_WARN("pskb_may_pull failed\n");
 715                 return 1;
 716         }
 717
 718         dh = dccp_hdr(skb);
 719
 720         /* If P.type is not understood, drop packet and return */
 721         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 722                 DCCP_WARN("invalid packet type\n");
 723                 return 1;
 724         }
 725
 726         /*
 727          * If P.Data Offset is too small for packet type, drop packet and return
 728          */
 729         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 730                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
 731                 return 1;
 732         }
 733         /*
 734          * If P.Data Offset is too too large for packet, drop packet and return
 735          */
 736         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 737                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
 738                 return 1;
 739         }
 740
 741         /*
 742          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 743          * has short sequence numbers), drop packet and return
 744          */
 745         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 746             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 747                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 748                           dccp_packet_name(dh->dccph_type));
 749                 return 1;
 750         }
 751
 752         /*
 753          * If P.CsCov is too large for the packet size, drop packet and return.
 754          * This must come _before_ checksumming (not as RFC 4340 suggests).
 755          */
 756         cscov = dccp_csum_coverage(skb);
 757         if (cscov > skb->len) {
 758                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 759                           dh->dccph_cscov, skb->len);
 760                 return 1;
 761         }
 762
 763         /* If header checksum is incorrect, drop packet and return.
 764          * (This step is completed in the AF-dependent functions.) */
 765         skb->csum = skb_checksum(skb, 0, cscov, 0);
 766
 767         return 0;
 768 }
 769
 770 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 771
 772 /* this is called when real data arrives */
 773 static int dccp_v4_rcv(struct sk_buff *skb)
 774 {
 775         const struct dccp_hdr *dh;
 776         const struct iphdr *iph;
 777         struct sock *sk;
 778         int min_cov;
 779
 780         /* Step 1: Check header basics */
 781
 782         if (dccp_invalid_packet(skb))
 783                 goto discard_it;
 784
 785         iph = ip_hdr(skb);
 786         /* Step 1: If header checksum is incorrect, drop packet and return */
 787         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 788                 DCCP_WARN("dropped packet with invalid checksum\n");
 789                 goto discard_it;
 790         }
 791
 792         dh = dccp_hdr(skb);
 793
 794         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 795         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 796
 797         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 798                       dccp_packet_name(dh->dccph_type),
 799                       &iph->saddr, ntohs(dh->dccph_sport),
 800                       &iph->daddr, ntohs(dh->dccph_dport),
 801                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 802
 803         if (dccp_packet_without_ack(skb)) {
 804                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 805                 dccp_pr_debug_cat("\n");
 806         } else {
 807                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 808                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 809                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 810         }
 811
 812         /* Step 2:
 813          *      Look up flow ID in table and get corresponding socket */
 814         sk = __inet_lookup_skb(&dccp_hashinfo, skb,
 815                                dh->dccph_sport, dh->dccph_dport);
 816         /*
 817          * Step 2:
 818          *      If no socket ...
 819          */
 820         if (sk == NULL) {
 821                 dccp_pr_debug("failed to look up flow ID in table and "
 822                               "get corresponding socket\n");
 823                 goto no_dccp_socket;
 824         }
 825
 826         /*
 827          * Step 2:
 828          *      ... or S.state == TIMEWAIT,
 829          *              Generate Reset(No Connection) unless P.type == Reset
 830          *              Drop packet and return
 831          */
 832         if (sk->sk_state == DCCP_TIME_WAIT) {
 833                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 834                 inet_twsk_put(inet_twsk(sk));
 835                 goto no_dccp_socket;
 836         }
 837
 838         /*
 839          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 840          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 841          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 842          */
 843         min_cov = dccp_sk(sk)->dccps_pcrlen;
 844         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 845                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 846                               dh->dccph_cscov, min_cov);
 847                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 848                  *         options (Section 11.7) with Drop Code 0, Protocol
 849                  *         Constraints."                                     */
 850                 goto discard_and_relse;
 851         }
 852
 853         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 854                 goto discard_and_relse;
 855         nf_reset(skb);
 856
 857         return sk_receive_skb(sk, skb, 1);
 858
 859 no_dccp_socket:
 860         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 861                 goto discard_it;
 862         /*
 863          * Step 2:
 864          *      If no socket ...
 865          *              Generate Reset(No Connection) unless P.type == Reset
 866          *              Drop packet and return
 867          */
 868         if (dh->dccph_type != DCCP_PKT_RESET) {
 869                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 870                                         DCCP_RESET_CODE_NO_CONNECTION;
 871                 dccp_v4_ctl_send_reset(sk, skb);
 872         }
 873
 874 discard_it:
 875         kfree_skb(skb);
 876         return 0;
 877
 878 discard_and_relse:
 879         sock_put(sk);
 880         goto discard_it;
 881 }
 882
 883 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 884         .queue_xmit        = ip_queue_xmit,
 885         .send_check        = dccp_v4_send_check,
 886         .rebuild_header    = inet_sk_rebuild_header,
 887         .conn_request      = dccp_v4_conn_request,
 888         .syn_recv_sock     = dccp_v4_request_recv_sock,
 889         .net_header_len    = sizeof(struct iphdr),
 890         .setsockopt        = ip_setsockopt,
 891         .getsockopt        = ip_getsockopt,
 892         .addr2sockaddr     = inet_csk_addr2sockaddr,
 893         .sockaddr_len      = sizeof(struct sockaddr_in),
 894         .bind_conflict     = inet_csk_bind_conflict,
 895 #ifdef CONFIG_COMPAT
 896         .compat_setsockopt = compat_ip_setsockopt,
 897         .compat_getsockopt = compat_ip_getsockopt,
 898 #endif
 899 };
 900
 901 static int dccp_v4_init_sock(struct sock *sk)
 902 {
 903         static __u8 dccp_v4_ctl_sock_initialized;
 904         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 905
 906         if (err == 0) {
 907                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 908                         dccp_v4_ctl_sock_initialized = 1;
 909                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 910         }
 911
 912         return err;
 913 }
 914
 915 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 916         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 917 };
 918
 919 static struct proto dccp_v4_prot = {
 920         .name                   = "DCCP",
 921         .owner                  = THIS_MODULE,
 922         .close                  = dccp_close,
 923         .connect                = dccp_v4_connect,
 924         .disconnect             = dccp_disconnect,
 925         .ioctl                  = dccp_ioctl,
 926         .init                   = dccp_v4_init_sock,
 927         .setsockopt             = dccp_setsockopt,
 928         .getsockopt             = dccp_getsockopt,
 929         .sendmsg                = dccp_sendmsg,
 930         .recvmsg                = dccp_recvmsg,
 931         .backlog_rcv            = dccp_v4_do_rcv,
 932         .hash                   = inet_hash,
 933         .unhash                 = inet_unhash,
 934         .accept                 = inet_csk_accept,
 935         .get_port               = inet_csk_get_port,
 936         .shutdown               = dccp_shutdown,
 937         .destroy                = dccp_destroy_sock,
 938         .orphan_count           = &dccp_orphan_count,
 939         .max_header             = MAX_DCCP_HEADER,
 940         .obj_size               = sizeof(struct dccp_sock),
 941         .slab_flags             = SLAB_DESTROY_BY_RCU,
 942         .rsk_prot               = &dccp_request_sock_ops,
 943         .twsk_prot              = &dccp_timewait_sock_ops,
 944         .h.hashinfo             = &dccp_hashinfo,
 945 #ifdef CONFIG_COMPAT
 946         .compat_setsockopt      = compat_dccp_setsockopt,
 947         .compat_getsockopt      = compat_dccp_getsockopt,
 948 #endif
 949 };
 950
 951 static struct net_protocol dccp_v4_protocol = {
 952         .handler        = dccp_v4_rcv,
 953         .err_handler    = dccp_v4_err,
 954         .no_policy      = 1,
 955         .netns_ok       = 1,
 956 };
 957
 958 static const struct proto_ops inet_dccp_ops = {
 959         .family            = PF_INET,
 960         .owner             = THIS_MODULE,
 961         .release           = inet_release,
 962         .bind              = inet_bind,
 963         .connect           = inet_stream_connect,
 964         .socketpair        = sock_no_socketpair,
 965         .accept            = inet_accept,
 966         .getname           = inet_getname,
 967         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 968         .poll              = dccp_poll,
 969         .ioctl             = inet_ioctl,
 970         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 971         .listen            = inet_dccp_listen,
 972         .shutdown          = inet_shutdown,
 973         .setsockopt        = sock_common_setsockopt,
 974         .getsockopt        = sock_common_getsockopt,
 975         .sendmsg           = inet_sendmsg,
 976         .recvmsg           = sock_common_recvmsg,
 977         .mmap              = sock_no_mmap,
 978         .sendpage          = sock_no_sendpage,
 979 #ifdef CONFIG_COMPAT
 980         .compat_setsockopt = compat_sock_common_setsockopt,
 981         .compat_getsockopt = compat_sock_common_getsockopt,
 982 #endif
 983 };
 984
 985 static struct inet_protosw dccp_v4_protosw = {
 986         .type           = SOCK_DCCP,
 987         .protocol       = IPPROTO_DCCP,
 988         .prot           = &dccp_v4_prot,
 989         .ops            = &inet_dccp_ops,
 990         .capability     = -1,
 991         .no_check       = 0,
 992         .flags          = INET_PROTOSW_ICSK,
 993 };
 994
 995 static int dccp_v4_init_net(struct net *net)
 996 {
 997         int err;
 998
 999         err = inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1000                                    SOCK_DCCP, IPPROTO_DCCP, net);
1001         return err;
1002 }
1003
1004 static void dccp_v4_exit_net(struct net *net)
1005 {
1006         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1007 }
1008
1009 static struct pernet_operations dccp_v4_ops = {
1010         .init   = dccp_v4_init_net,
1011         .exit   = dccp_v4_exit_net,
1012 };
1013
1014 static int __init dccp_v4_init(void)
1015 {
1016         int err = proto_register(&dccp_v4_prot, 1);
1017
1018         if (err != 0)
1019                 goto out;
1020
1021         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1022         if (err != 0)
1023                 goto out_proto_unregister;
1024
1025         inet_register_protosw(&dccp_v4_protosw);
1026
1027         err = register_pernet_subsys(&dccp_v4_ops);
1028         if (err)
1029                 goto out_destroy_ctl_sock;
1030 out:
1031         return err;
1032 out_destroy_ctl_sock:
1033         inet_unregister_protosw(&dccp_v4_protosw);
1034         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1035 out_proto_unregister:
1036         proto_unregister(&dccp_v4_prot);
1037         goto out;
1038 }
1039
1040 static void __exit dccp_v4_exit(void)
1041 {
1042         unregister_pernet_subsys(&dccp_v4_ops);
1043         inet_unregister_protosw(&dccp_v4_protosw);
1044         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1045         proto_unregister(&dccp_v4_prot);
1046 }
1047
1048 module_init(dccp_v4_init);
1049 module_exit(dccp_v4_exit);
1050
1051 /*
1052  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1053  * values directly, Also cover the case where the protocol is not specified,
1054  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1055  */
1056 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1057 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1058 MODULE_LICENSE("GPL");
1059 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1060 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");