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->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(rxskb->dst->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 (rxskb->rtable->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 = 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         kfree(inet_rsk(req)->opt);
 549 }
 550
 551 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 552         .family         = PF_INET,
 553         .obj_size       = sizeof(struct dccp_request_sock),
 554         .rtx_syn_ack    = dccp_v4_send_response,
 555         .send_ack       = dccp_reqsk_send_ack,
 556         .destructor     = dccp_v4_reqsk_destructor,
 557         .send_reset     = dccp_v4_ctl_send_reset,
 558 };
 559
 560 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 561 {
 562         struct inet_request_sock *ireq;
 563         struct request_sock *req;
 564         struct dccp_request_sock *dreq;
 565         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 566         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 567
 568         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 569         if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 570                 return 0;       /* discard, don't send a reset here */
 571
 572         if (dccp_bad_service_code(sk, service)) {
 573                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 574                 goto drop;
 575         }
 576         /*
 577          * TW buckets are converted to open requests without
 578          * limitations, they conserve resources and peer is
 579          * evidently real one.
 580          */
 581         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 582         if (inet_csk_reqsk_queue_is_full(sk))
 583                 goto drop;
 584
 585         /*
 586          * Accept backlog is full. If we have already queued enough
 587          * of warm entries in syn queue, drop request. It is better than
 588          * clogging syn queue with openreqs with exponentially increasing
 589          * timeout.
 590          */
 591         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 592                 goto drop;
 593
 594         req = inet_reqsk_alloc(&dccp_request_sock_ops);
 595         if (req == NULL)
 596                 goto drop;
 597
 598         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 599                 goto drop_and_free;
 600
 601         dreq = dccp_rsk(req);
 602         if (dccp_parse_options(sk, dreq, skb))
 603                 goto drop_and_free;
 604
 605         if (security_inet_conn_request(sk, skb, req))
 606                 goto drop_and_free;
 607
 608         ireq = inet_rsk(req);
 609         ireq->loc_addr = ip_hdr(skb)->daddr;
 610         ireq->rmt_addr = ip_hdr(skb)->saddr;
 611
 612         /*
 613          * Step 3: Process LISTEN state
 614          *
 615          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 616          *
 617          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 618          * dccp_create_openreq_child.
 619          */
 620         dreq->dreq_isr     = dcb->dccpd_seq;
 621         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 622         dreq->dreq_service = service;
 623
 624         if (dccp_v4_send_response(sk, req))
 625                 goto drop_and_free;
 626
 627         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 628         return 0;
 629
 630 drop_and_free:
 631         reqsk_free(req);
 632 drop:
 633         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 634         return -1;
 635 }
 636
 637 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 638
 639 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 640 {
 641         struct dccp_hdr *dh = dccp_hdr(skb);
 642
 643         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 644                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 645                         goto reset;
 646                 return 0;
 647         }
 648
 649         /*
 650          *  Step 3: Process LISTEN state
 651          *       If P.type == Request or P contains a valid Init Cookie option,
 652          *            (* Must scan the packet's options to check for Init
 653          *               Cookies.  Only Init Cookies are processed here,
 654          *               however; other options are processed in Step 8.  This
 655          *               scan need only be performed if the endpoint uses Init
 656          *               Cookies *)
 657          *            (* Generate a new socket and switch to that socket *)
 658          *            Set S := new socket for this port pair
 659          *            S.state = RESPOND
 660          *            Choose S.ISS (initial seqno) or set from Init Cookies
 661          *            Initialize S.GAR := S.ISS
 662          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 663          *            Continue with S.state == RESPOND
 664          *            (* A Response packet will be generated in Step 11 *)
 665          *       Otherwise,
 666          *            Generate Reset(No Connection) unless P.type == Reset
 667          *            Drop packet and return
 668          *
 669          * NOTE: the check for the packet types is done in
 670          *       dccp_rcv_state_process
 671          */
 672         if (sk->sk_state == DCCP_LISTEN) {
 673                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 674
 675                 if (nsk == NULL)
 676                         goto discard;
 677
 678                 if (nsk != sk) {
 679                         if (dccp_child_process(sk, nsk, skb))
 680                                 goto reset;
 681                         return 0;
 682                 }
 683         }
 684
 685         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 686                 goto reset;
 687         return 0;
 688
 689 reset:
 690         dccp_v4_ctl_send_reset(sk, skb);
 691 discard:
 692         kfree_skb(skb);
 693         return 0;
 694 }
 695
 696 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 697
 698 /**
 699  *      dccp_invalid_packet  -  check for malformed packets
 700  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 701  *      Packets that fail these checks are ignored and do not receive Resets.
 702  */
 703 int dccp_invalid_packet(struct sk_buff *skb)
 704 {
 705         const struct dccp_hdr *dh;
 706         unsigned int cscov;
 707
 708         if (skb->pkt_type != PACKET_HOST)
 709                 return 1;
 710
 711         /* If the packet is shorter than 12 bytes, drop packet and return */
 712         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 713                 DCCP_WARN("pskb_may_pull failed\n");
 714                 return 1;
 715         }
 716
 717         dh = dccp_hdr(skb);
 718
 719         /* If P.type is not understood, drop packet and return */
 720         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 721                 DCCP_WARN("invalid packet type\n");
 722                 return 1;
 723         }
 724
 725         /*
 726          * If P.Data Offset is too small for packet type, drop packet and return
 727          */
 728         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 729                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
 730                 return 1;
 731         }
 732         /*
 733          * If P.Data Offset is too too large for packet, drop packet and return
 734          */
 735         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 736                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
 737                 return 1;
 738         }
 739
 740         /*
 741          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 742          * has short sequence numbers), drop packet and return
 743          */
 744         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 745             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 746                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 747                           dccp_packet_name(dh->dccph_type));
 748                 return 1;
 749         }
 750
 751         /*
 752          * If P.CsCov is too large for the packet size, drop packet and return.
 753          * This must come _before_ checksumming (not as RFC 4340 suggests).
 754          */
 755         cscov = dccp_csum_coverage(skb);
 756         if (cscov > skb->len) {
 757                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 758                           dh->dccph_cscov, skb->len);
 759                 return 1;
 760         }
 761
 762         /* If header checksum is incorrect, drop packet and return.
 763          * (This step is completed in the AF-dependent functions.) */
 764         skb->csum = skb_checksum(skb, 0, cscov, 0);
 765
 766         return 0;
 767 }
 768
 769 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 770
 771 /* this is called when real data arrives */
 772 static int dccp_v4_rcv(struct sk_buff *skb)
 773 {
 774         const struct dccp_hdr *dh;
 775         const struct iphdr *iph;
 776         struct sock *sk;
 777         int min_cov;
 778
 779         /* Step 1: Check header basics */
 780
 781         if (dccp_invalid_packet(skb))
 782                 goto discard_it;
 783
 784         iph = ip_hdr(skb);
 785         /* Step 1: If header checksum is incorrect, drop packet and return */
 786         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 787                 DCCP_WARN("dropped packet with invalid checksum\n");
 788                 goto discard_it;
 789         }
 790
 791         dh = dccp_hdr(skb);
 792
 793         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 794         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 795
 796         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 797                       dccp_packet_name(dh->dccph_type),
 798                       &iph->saddr, ntohs(dh->dccph_sport),
 799                       &iph->daddr, ntohs(dh->dccph_dport),
 800                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 801
 802         if (dccp_packet_without_ack(skb)) {
 803                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 804                 dccp_pr_debug_cat("\n");
 805         } else {
 806                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 807                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 808                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 809         }
 810
 811         /* Step 2:
 812          *      Look up flow ID in table and get corresponding socket */
 813         sk = __inet_lookup_skb(&dccp_hashinfo, skb,
 814                                dh->dccph_sport, dh->dccph_dport);
 815         /*
 816          * Step 2:
 817          *      If no socket ...
 818          */
 819         if (sk == NULL) {
 820                 dccp_pr_debug("failed to look up flow ID in table and "
 821                               "get corresponding socket\n");
 822                 goto no_dccp_socket;
 823         }
 824
 825         /*
 826          * Step 2:
 827          *      ... or S.state == TIMEWAIT,
 828          *              Generate Reset(No Connection) unless P.type == Reset
 829          *              Drop packet and return
 830          */
 831         if (sk->sk_state == DCCP_TIME_WAIT) {
 832                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 833                 inet_twsk_put(inet_twsk(sk));
 834                 goto no_dccp_socket;
 835         }
 836
 837         /*
 838          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 839          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 840          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 841          */
 842         min_cov = dccp_sk(sk)->dccps_pcrlen;
 843         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 844                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 845                               dh->dccph_cscov, min_cov);
 846                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 847                  *         options (Section 11.7) with Drop Code 0, Protocol
 848                  *         Constraints."                                     */
 849                 goto discard_and_relse;
 850         }
 851
 852         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 853                 goto discard_and_relse;
 854         nf_reset(skb);
 855
 856         return sk_receive_skb(sk, skb, 1);
 857
 858 no_dccp_socket:
 859         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 860                 goto discard_it;
 861         /*
 862          * Step 2:
 863          *      If no socket ...
 864          *              Generate Reset(No Connection) unless P.type == Reset
 865          *              Drop packet and return
 866          */
 867         if (dh->dccph_type != DCCP_PKT_RESET) {
 868                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 869                                         DCCP_RESET_CODE_NO_CONNECTION;
 870                 dccp_v4_ctl_send_reset(sk, skb);
 871         }
 872
 873 discard_it:
 874         kfree_skb(skb);
 875         return 0;
 876
 877 discard_and_relse:
 878         sock_put(sk);
 879         goto discard_it;
 880 }
 881
 882 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 883         .queue_xmit        = ip_queue_xmit,
 884         .send_check        = dccp_v4_send_check,
 885         .rebuild_header    = inet_sk_rebuild_header,
 886         .conn_request      = dccp_v4_conn_request,
 887         .syn_recv_sock     = dccp_v4_request_recv_sock,
 888         .net_header_len    = sizeof(struct iphdr),
 889         .setsockopt        = ip_setsockopt,
 890         .getsockopt        = ip_getsockopt,
 891         .addr2sockaddr     = inet_csk_addr2sockaddr,
 892         .sockaddr_len      = sizeof(struct sockaddr_in),
 893         .bind_conflict     = inet_csk_bind_conflict,
 894 #ifdef CONFIG_COMPAT
 895         .compat_setsockopt = compat_ip_setsockopt,
 896         .compat_getsockopt = compat_ip_getsockopt,
 897 #endif
 898 };
 899
 900 static int dccp_v4_init_sock(struct sock *sk)
 901 {
 902         static __u8 dccp_v4_ctl_sock_initialized;
 903         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 904
 905         if (err == 0) {
 906                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 907                         dccp_v4_ctl_sock_initialized = 1;
 908                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 909         }
 910
 911         return err;
 912 }
 913
 914 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 915         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 916 };
 917
 918 static struct proto dccp_v4_prot = {
 919         .name                   = "DCCP",
 920         .owner                  = THIS_MODULE,
 921         .close                  = dccp_close,
 922         .connect                = dccp_v4_connect,
 923         .disconnect             = dccp_disconnect,
 924         .ioctl                  = dccp_ioctl,
 925         .init                   = dccp_v4_init_sock,
 926         .setsockopt             = dccp_setsockopt,
 927         .getsockopt             = dccp_getsockopt,
 928         .sendmsg                = dccp_sendmsg,
 929         .recvmsg                = dccp_recvmsg,
 930         .backlog_rcv            = dccp_v4_do_rcv,
 931         .hash                   = inet_hash,
 932         .unhash                 = inet_unhash,
 933         .accept                 = inet_csk_accept,
 934         .get_port               = inet_csk_get_port,
 935         .shutdown               = dccp_shutdown,
 936         .destroy                = dccp_destroy_sock,
 937         .orphan_count           = &dccp_orphan_count,
 938         .max_header             = MAX_DCCP_HEADER,
 939         .obj_size               = sizeof(struct dccp_sock),
 940         .rsk_prot               = &dccp_request_sock_ops,
 941         .twsk_prot              = &dccp_timewait_sock_ops,
 942         .h.hashinfo             = &dccp_hashinfo,
 943 #ifdef CONFIG_COMPAT
 944         .compat_setsockopt      = compat_dccp_setsockopt,
 945         .compat_getsockopt      = compat_dccp_getsockopt,
 946 #endif
 947 };
 948
 949 static struct net_protocol dccp_v4_protocol = {
 950         .handler        = dccp_v4_rcv,
 951         .err_handler    = dccp_v4_err,
 952         .no_policy      = 1,
 953         .netns_ok       = 1,
 954 };
 955
 956 static const struct proto_ops inet_dccp_ops = {
 957         .family            = PF_INET,
 958         .owner             = THIS_MODULE,
 959         .release           = inet_release,
 960         .bind              = inet_bind,
 961         .connect           = inet_stream_connect,
 962         .socketpair        = sock_no_socketpair,
 963         .accept            = inet_accept,
 964         .getname           = inet_getname,
 965         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 966         .poll              = dccp_poll,
 967         .ioctl             = inet_ioctl,
 968         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 969         .listen            = inet_dccp_listen,
 970         .shutdown          = inet_shutdown,
 971         .setsockopt        = sock_common_setsockopt,
 972         .getsockopt        = sock_common_getsockopt,
 973         .sendmsg           = inet_sendmsg,
 974         .recvmsg           = sock_common_recvmsg,
 975         .mmap              = sock_no_mmap,
 976         .sendpage          = sock_no_sendpage,
 977 #ifdef CONFIG_COMPAT
 978         .compat_setsockopt = compat_sock_common_setsockopt,
 979         .compat_getsockopt = compat_sock_common_getsockopt,
 980 #endif
 981 };
 982
 983 static struct inet_protosw dccp_v4_protosw = {
 984         .type           = SOCK_DCCP,
 985         .protocol       = IPPROTO_DCCP,
 986         .prot           = &dccp_v4_prot,
 987         .ops            = &inet_dccp_ops,
 988         .capability     = -1,
 989         .no_check       = 0,
 990         .flags          = INET_PROTOSW_ICSK,
 991 };
 992
 993 static int dccp_v4_init_net(struct net *net)
 994 {
 995         int err;
 996
 997         err = inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
 998                                    SOCK_DCCP, IPPROTO_DCCP, net);
 999         return err;
1000 }
1001
1002 static void dccp_v4_exit_net(struct net *net)
1003 {
1004         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1005 }
1006
1007 static struct pernet_operations dccp_v4_ops = {
1008         .init   = dccp_v4_init_net,
1009         .exit   = dccp_v4_exit_net,
1010 };
1011
1012 static int __init dccp_v4_init(void)
1013 {
1014         int err = proto_register(&dccp_v4_prot, 1);
1015
1016         if (err != 0)
1017                 goto out;
1018
1019         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1020         if (err != 0)
1021                 goto out_proto_unregister;
1022
1023         inet_register_protosw(&dccp_v4_protosw);
1024
1025         err = register_pernet_subsys(&dccp_v4_ops);
1026         if (err)
1027                 goto out_destroy_ctl_sock;
1028 out:
1029         return err;
1030 out_destroy_ctl_sock:
1031         inet_unregister_protosw(&dccp_v4_protosw);
1032         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1033 out_proto_unregister:
1034         proto_unregister(&dccp_v4_prot);
1035         goto out;
1036 }
1037
1038 static void __exit dccp_v4_exit(void)
1039 {
1040         unregister_pernet_subsys(&dccp_v4_ops);
1041         inet_unregister_protosw(&dccp_v4_protosw);
1042         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1043         proto_unregister(&dccp_v4_prot);
1044 }
1045
1046 module_init(dccp_v4_init);
1047 module_exit(dccp_v4_exit);
1048
1049 /*
1050  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1051  * values directly, Also cover the case where the protocol is not specified,
1052  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1053  */
1054 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1055 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1056 MODULE_LICENSE("GPL");
1057 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1058 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");