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  * This is the global socket data structure 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 static struct socket *dccp_v4_ctl_socket;
  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->saddr,
  67                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  68                                IPPROTO_DCCP,
  69                                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->saddr == 0)
  82                 inet->saddr = rt->rt_src;
  83         inet->rcv_saddr = inet->saddr;
  84
  85         inet->dport = usin->sin_port;
  86         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->sport, inet->dport,
 103                                 sk);
 104         if (err != 0)
 105                 goto failure;
 106
 107         /* OK, now commit destination to socket.  */
 108         sk_setup_caps(sk, &rt->u.dst);
 109
 110         dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, inet->daddr,
 111                                                     inet->sport, inet->dport);
 112         inet->id = dp->dccps_iss ^ jiffies;
 113
 114         err = dccp_connect(sk);
 115         rt = NULL;
 116         if (err != 0)
 117                 goto failure;
 118 out:
 119         return err;
 120 failure:
 121         /*
 122          * This unhashes the socket and releases the local port, if necessary.
 123          */
 124         dccp_set_state(sk, DCCP_CLOSED);
 125         ip_rt_put(rt);
 126         sk->sk_route_caps = 0;
 127         inet->dport = 0;
 128         goto out;
 129 }
 130
 131 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 132
 133 /*
 134  * This routine does path mtu discovery as defined in RFC1191.
 135  */
 136 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 137                                           const struct iphdr *iph,
 138                                           u32 mtu)
 139 {
 140         struct dst_entry *dst;
 141         const struct inet_sock *inet = inet_sk(sk);
 142         const struct dccp_sock *dp = dccp_sk(sk);
 143
 144         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 145          * send out by Linux are always < 576bytes so they should go through
 146          * unfragmented).
 147          */
 148         if (sk->sk_state == DCCP_LISTEN)
 149                 return;
 150
 151         /* We don't check in the destentry if pmtu discovery is forbidden
 152          * on this route. We just assume that no packet_to_big packets
 153          * are send back when pmtu discovery is not active.
 154          * There is a small race when the user changes this flag in the
 155          * route, but I think that's acceptable.
 156          */
 157         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 158                 return;
 159
 160         dst->ops->update_pmtu(dst, mtu);
 161
 162         /* Something is about to be wrong... Remember soft error
 163          * for the case, if this connection will not able to recover.
 164          */
 165         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 166                 sk->sk_err_soft = EMSGSIZE;
 167
 168         mtu = dst_mtu(dst);
 169
 170         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 171             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 172                 dccp_sync_mss(sk, mtu);
 173
 174                 /*
 175                  * From RFC 4340, sec. 14.1:
 176                  *
 177                  *      DCCP-Sync packets are the best choice for upward
 178                  *      probing, since DCCP-Sync probes do not risk application
 179                  *      data loss.
 180                  */
 181                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 182         } /* else let the usual retransmit timer handle it */
 183 }
 184
 185 /*
 186  * This routine is called by the ICMP module when it gets some sort of error
 187  * condition. If err < 0 then the socket should be closed and the error
 188  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 189  * After adjustment header points to the first 8 bytes of the tcp header. We
 190  * need to find the appropriate port.
 191  *
 192  * The locking strategy used here is very "optimistic". When someone else
 193  * accesses the socket the ICMP is just dropped and for some paths there is no
 194  * check at all. A more general error queue to queue errors for later handling
 195  * is probably better.
 196  */
 197 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 198 {
 199         const struct iphdr *iph = (struct iphdr *)skb->data;
 200         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 201                                                         (iph->ihl << 2));
 202         struct dccp_sock *dp;
 203         struct inet_sock *inet;
 204         const int type = icmp_hdr(skb)->type;
 205         const int code = icmp_hdr(skb)->code;
 206         struct sock *sk;
 207         __u64 seq;
 208         int err;
 209
 210         if (skb->len < (iph->ihl << 2) + 8) {
 211                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 212                 return;
 213         }
 214
 215         sk = inet_lookup(&init_net, &dccp_hashinfo, iph->daddr, dh->dccph_dport,
 216                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 217         if (sk == NULL) {
 218                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 219                 return;
 220         }
 221
 222         if (sk->sk_state == DCCP_TIME_WAIT) {
 223                 inet_twsk_put(inet_twsk(sk));
 224                 return;
 225         }
 226
 227         bh_lock_sock(sk);
 228         /* If too many ICMPs get dropped on busy
 229          * servers this needs to be solved differently.
 230          */
 231         if (sock_owned_by_user(sk))
 232                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 233
 234         if (sk->sk_state == DCCP_CLOSED)
 235                 goto out;
 236
 237         dp = dccp_sk(sk);
 238         seq = dccp_hdr_seq(dh);
 239         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 240             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 241                 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 242                 goto out;
 243         }
 244
 245         switch (type) {
 246         case ICMP_SOURCE_QUENCH:
 247                 /* Just silently ignore these. */
 248                 goto out;
 249         case ICMP_PARAMETERPROB:
 250                 err = EPROTO;
 251                 break;
 252         case ICMP_DEST_UNREACH:
 253                 if (code > NR_ICMP_UNREACH)
 254                         goto out;
 255
 256                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 257                         if (!sock_owned_by_user(sk))
 258                                 dccp_do_pmtu_discovery(sk, iph, info);
 259                         goto out;
 260                 }
 261
 262                 err = icmp_err_convert[code].errno;
 263                 break;
 264         case ICMP_TIME_EXCEEDED:
 265                 err = EHOSTUNREACH;
 266                 break;
 267         default:
 268                 goto out;
 269         }
 270
 271         switch (sk->sk_state) {
 272                 struct request_sock *req , **prev;
 273         case DCCP_LISTEN:
 274                 if (sock_owned_by_user(sk))
 275                         goto out;
 276                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 277                                           iph->daddr, iph->saddr);
 278                 if (!req)
 279                         goto out;
 280
 281                 /*
 282                  * ICMPs are not backlogged, hence we cannot get an established
 283                  * socket here.
 284                  */
 285                 BUG_TRAP(!req->sk);
 286
 287                 if (seq != dccp_rsk(req)->dreq_iss) {
 288                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 289                         goto out;
 290                 }
 291                 /*
 292                  * Still in RESPOND, just remove it silently.
 293                  * There is no good way to pass the error to the newly
 294                  * created socket, and POSIX does not want network
 295                  * errors returned from accept().
 296                  */
 297                 inet_csk_reqsk_queue_drop(sk, req, prev);
 298                 goto out;
 299
 300         case DCCP_REQUESTING:
 301         case DCCP_RESPOND:
 302                 if (!sock_owned_by_user(sk)) {
 303                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 304                         sk->sk_err = err;
 305
 306                         sk->sk_error_report(sk);
 307
 308                         dccp_done(sk);
 309                 } else
 310                         sk->sk_err_soft = err;
 311                 goto out;
 312         }
 313
 314         /* If we've already connected we will keep trying
 315          * until we time out, or the user gives up.
 316          *
 317          * rfc1122 4.2.3.9 allows to consider as hard errors
 318          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 319          * but it is obsoleted by pmtu discovery).
 320          *
 321          * Note, that in modern internet, where routing is unreliable
 322          * and in each dark corner broken firewalls sit, sending random
 323          * errors ordered by their masters even this two messages finally lose
 324          * their original sense (even Linux sends invalid PORT_UNREACHs)
 325          *
 326          * Now we are in compliance with RFCs.
 327          *                                                      --ANK (980905)
 328          */
 329
 330         inet = inet_sk(sk);
 331         if (!sock_owned_by_user(sk) && inet->recverr) {
 332                 sk->sk_err = err;
 333                 sk->sk_error_report(sk);
 334         } else /* Only an error on timeout */
 335                 sk->sk_err_soft = err;
 336 out:
 337         bh_unlock_sock(sk);
 338         sock_put(sk);
 339 }
 340
 341 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 342                                       __be32 src, __be32 dst)
 343 {
 344         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 345 }
 346
 347 void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
 348 {
 349         const struct inet_sock *inet = inet_sk(sk);
 350         struct dccp_hdr *dh = dccp_hdr(skb);
 351
 352         dccp_csum_outgoing(skb);
 353         dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
 354 }
 355
 356 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 357
 358 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 359 {
 360         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 361                                            ip_hdr(skb)->saddr,
 362                                            dccp_hdr(skb)->dccph_dport,
 363                                            dccp_hdr(skb)->dccph_sport);
 364 }
 365
 366 /*
 367  * The three way handshake has completed - we got a valid ACK or DATAACK -
 368  * now create the new socket.
 369  *
 370  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 371  */
 372 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 373                                        struct request_sock *req,
 374                                        struct dst_entry *dst)
 375 {
 376         struct inet_request_sock *ireq;
 377         struct inet_sock *newinet;
 378         struct sock *newsk;
 379
 380         if (sk_acceptq_is_full(sk))
 381                 goto exit_overflow;
 382
 383         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 384                 goto exit;
 385
 386         newsk = dccp_create_openreq_child(sk, req, skb);
 387         if (newsk == NULL)
 388                 goto exit;
 389
 390         sk_setup_caps(newsk, dst);
 391
 392         newinet            = inet_sk(newsk);
 393         ireq               = inet_rsk(req);
 394         newinet->daddr     = ireq->rmt_addr;
 395         newinet->rcv_saddr = ireq->loc_addr;
 396         newinet->saddr     = ireq->loc_addr;
 397         newinet->opt       = ireq->opt;
 398         ireq->opt          = NULL;
 399         newinet->mc_index  = inet_iif(skb);
 400         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 401         newinet->id        = jiffies;
 402
 403         dccp_sync_mss(newsk, dst_mtu(dst));
 404
 405         __inet_hash_nolisten(newsk);
 406         __inet_inherit_port(sk, newsk);
 407
 408         return newsk;
 409
 410 exit_overflow:
 411         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
 412 exit:
 413         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
 414         dst_release(dst);
 415         return NULL;
 416 }
 417
 418 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 419
 420 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 421 {
 422         const struct dccp_hdr *dh = dccp_hdr(skb);
 423         const struct iphdr *iph = ip_hdr(skb);
 424         struct sock *nsk;
 425         struct request_sock **prev;
 426         /* Find possible connection requests. */
 427         struct request_sock *req = inet_csk_search_req(sk, &prev,
 428                                                        dh->dccph_sport,
 429                                                        iph->saddr, iph->daddr);
 430         if (req != NULL)
 431                 return dccp_check_req(sk, skb, req, prev);
 432
 433         nsk = inet_lookup_established(&init_net, &dccp_hashinfo,
 434                                       iph->saddr, dh->dccph_sport,
 435                                       iph->daddr, dh->dccph_dport,
 436                                       inet_iif(skb));
 437         if (nsk != NULL) {
 438                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 439                         bh_lock_sock(nsk);
 440                         return nsk;
 441                 }
 442                 inet_twsk_put(inet_twsk(nsk));
 443                 return NULL;
 444         }
 445
 446         return sk;
 447 }
 448
 449 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
 450                                            struct sk_buff *skb)
 451 {
 452         struct rtable *rt;
 453         struct flowi fl = { .oif = skb->rtable->rt_iif,
 454                             .nl_u = { .ip4_u =
 455                                       { .daddr = ip_hdr(skb)->saddr,
 456                                         .saddr = ip_hdr(skb)->daddr,
 457                                         .tos = RT_CONN_FLAGS(sk) } },
 458                             .proto = sk->sk_protocol,
 459                             .uli_u = { .ports =
 460                                        { .sport = dccp_hdr(skb)->dccph_dport,
 461                                          .dport = dccp_hdr(skb)->dccph_sport }
 462                                      }
 463                           };
 464
 465         security_skb_classify_flow(skb, &fl);
 466         if (ip_route_output_flow(&init_net, &rt, &fl, sk, 0)) {
 467                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 468                 return NULL;
 469         }
 470
 471         return &rt->u.dst;
 472 }
 473
 474 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
 475 {
 476         int err = -1;
 477         struct sk_buff *skb;
 478         struct dst_entry *dst;
 479
 480         dst = inet_csk_route_req(sk, req);
 481         if (dst == NULL)
 482                 goto out;
 483
 484         skb = dccp_make_response(sk, dst, req);
 485         if (skb != NULL) {
 486                 const struct inet_request_sock *ireq = inet_rsk(req);
 487                 struct dccp_hdr *dh = dccp_hdr(skb);
 488
 489                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
 490                                                               ireq->rmt_addr);
 491                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 492                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 493                                             ireq->rmt_addr,
 494                                             ireq->opt);
 495                 err = net_xmit_eval(err);
 496         }
 497
 498 out:
 499         dst_release(dst);
 500         return err;
 501 }
 502
 503 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
 504 {
 505         int err;
 506         const struct iphdr *rxiph;
 507         struct sk_buff *skb;
 508         struct dst_entry *dst;
 509
 510         /* Never send a reset in response to a reset. */
 511         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 512                 return;
 513
 514         if (rxskb->rtable->rt_type != RTN_LOCAL)
 515                 return;
 516
 517         dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
 518         if (dst == NULL)
 519                 return;
 520
 521         skb = dccp_ctl_make_reset(dccp_v4_ctl_socket, rxskb);
 522         if (skb == NULL)
 523                 goto out;
 524
 525         rxiph = ip_hdr(rxskb);
 526         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 527                                                                  rxiph->daddr);
 528         skb->dst = dst_clone(dst);
 529
 530         bh_lock_sock(dccp_v4_ctl_socket->sk);
 531         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 532                                     rxiph->daddr, rxiph->saddr, NULL);
 533         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 534
 535         if (net_xmit_eval(err) == 0) {
 536                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 537                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 538         }
 539 out:
 540          dst_release(dst);
 541 }
 542
 543 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 544 {
 545         kfree(inet_rsk(req)->opt);
 546 }
 547
 548 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 549         .family         = PF_INET,
 550         .obj_size       = sizeof(struct dccp_request_sock),
 551         .rtx_syn_ack    = dccp_v4_send_response,
 552         .send_ack       = dccp_reqsk_send_ack,
 553         .destructor     = dccp_v4_reqsk_destructor,
 554         .send_reset     = dccp_v4_ctl_send_reset,
 555 };
 556
 557 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 558 {
 559         struct inet_request_sock *ireq;
 560         struct request_sock *req;
 561         struct dccp_request_sock *dreq;
 562         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 563         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 564
 565         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 566         if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 567                 return 0;       /* discard, don't send a reset here */
 568
 569         if (dccp_bad_service_code(sk, service)) {
 570                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 571                 goto drop;
 572         }
 573         /*
 574          * TW buckets are converted to open requests without
 575          * limitations, they conserve resources and peer is
 576          * evidently real one.
 577          */
 578         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 579         if (inet_csk_reqsk_queue_is_full(sk))
 580                 goto drop;
 581
 582         /*
 583          * Accept backlog is full. If we have already queued enough
 584          * of warm entries in syn queue, drop request. It is better than
 585          * clogging syn queue with openreqs with exponentially increasing
 586          * timeout.
 587          */
 588         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 589                 goto drop;
 590
 591         req = reqsk_alloc(&dccp_request_sock_ops);
 592         if (req == NULL)
 593                 goto drop;
 594
 595         dccp_reqsk_init(req, skb);
 596
 597         dreq = dccp_rsk(req);
 598         if (dccp_parse_options(sk, dreq, skb))
 599                 goto drop_and_free;
 600
 601         if (security_inet_conn_request(sk, skb, req))
 602                 goto drop_and_free;
 603
 604         ireq = inet_rsk(req);
 605         ireq->loc_addr = ip_hdr(skb)->daddr;
 606         ireq->rmt_addr = ip_hdr(skb)->saddr;
 607         ireq->opt       = NULL;
 608
 609         /*
 610          * Step 3: Process LISTEN state
 611          *
 612          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 613          *
 614          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 615          * dccp_create_openreq_child.
 616          */
 617         dreq->dreq_isr     = dcb->dccpd_seq;
 618         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 619         dreq->dreq_service = service;
 620
 621         if (dccp_v4_send_response(sk, req))
 622                 goto drop_and_free;
 623
 624         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 625         return 0;
 626
 627 drop_and_free:
 628         reqsk_free(req);
 629 drop:
 630         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 631         return -1;
 632 }
 633
 634 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 635
 636 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 637 {
 638         struct dccp_hdr *dh = dccp_hdr(skb);
 639
 640         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 641                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 642                         goto reset;
 643                 return 0;
 644         }
 645
 646         /*
 647          *  Step 3: Process LISTEN state
 648          *       If P.type == Request or P contains a valid Init Cookie option,
 649          *            (* Must scan the packet's options to check for Init
 650          *               Cookies.  Only Init Cookies are processed here,
 651          *               however; other options are processed in Step 8.  This
 652          *               scan need only be performed if the endpoint uses Init
 653          *               Cookies *)
 654          *            (* Generate a new socket and switch to that socket *)
 655          *            Set S := new socket for this port pair
 656          *            S.state = RESPOND
 657          *            Choose S.ISS (initial seqno) or set from Init Cookies
 658          *            Initialize S.GAR := S.ISS
 659          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 660          *            Continue with S.state == RESPOND
 661          *            (* A Response packet will be generated in Step 11 *)
 662          *       Otherwise,
 663          *            Generate Reset(No Connection) unless P.type == Reset
 664          *            Drop packet and return
 665          *
 666          * NOTE: the check for the packet types is done in
 667          *       dccp_rcv_state_process
 668          */
 669         if (sk->sk_state == DCCP_LISTEN) {
 670                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 671
 672                 if (nsk == NULL)
 673                         goto discard;
 674
 675                 if (nsk != sk) {
 676                         if (dccp_child_process(sk, nsk, skb))
 677                                 goto reset;
 678                         return 0;
 679                 }
 680         }
 681
 682         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 683                 goto reset;
 684         return 0;
 685
 686 reset:
 687         dccp_v4_ctl_send_reset(sk, skb);
 688 discard:
 689         kfree_skb(skb);
 690         return 0;
 691 }
 692
 693 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 694
 695 /**
 696  *      dccp_invalid_packet  -  check for malformed packets
 697  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 698  *      Packets that fail these checks are ignored and do not receive Resets.
 699  */
 700 int dccp_invalid_packet(struct sk_buff *skb)
 701 {
 702         const struct dccp_hdr *dh;
 703         unsigned int cscov;
 704
 705         if (skb->pkt_type != PACKET_HOST)
 706                 return 1;
 707
 708         /* If the packet is shorter than 12 bytes, drop packet and return */
 709         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 710                 DCCP_WARN("pskb_may_pull failed\n");
 711                 return 1;
 712         }
 713
 714         dh = dccp_hdr(skb);
 715
 716         /* If P.type is not understood, drop packet and return */
 717         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 718                 DCCP_WARN("invalid packet type\n");
 719                 return 1;
 720         }
 721
 722         /*
 723          * If P.Data Offset is too small for packet type, drop packet and return
 724          */
 725         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 726                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
 727                 return 1;
 728         }
 729         /*
 730          * If P.Data Offset is too too large for packet, drop packet and return
 731          */
 732         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 733                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
 734                 return 1;
 735         }
 736
 737         /*
 738          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 739          * has short sequence numbers), drop packet and return
 740          */
 741         if (dh->dccph_type >= DCCP_PKT_DATA    &&
 742             dh->dccph_type <= DCCP_PKT_DATAACK && dh->dccph_x == 0)  {
 743                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 744                           dccp_packet_name(dh->dccph_type));
 745                 return 1;
 746         }
 747
 748         /*
 749          * If P.CsCov is too large for the packet size, drop packet and return.
 750          * This must come _before_ checksumming (not as RFC 4340 suggests).
 751          */
 752         cscov = dccp_csum_coverage(skb);
 753         if (cscov > skb->len) {
 754                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 755                           dh->dccph_cscov, skb->len);
 756                 return 1;
 757         }
 758
 759         /* If header checksum is incorrect, drop packet and return.
 760          * (This step is completed in the AF-dependent functions.) */
 761         skb->csum = skb_checksum(skb, 0, cscov, 0);
 762
 763         return 0;
 764 }
 765
 766 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 767
 768 /* this is called when real data arrives */
 769 static int dccp_v4_rcv(struct sk_buff *skb)
 770 {
 771         const struct dccp_hdr *dh;
 772         const struct iphdr *iph;
 773         struct sock *sk;
 774         int min_cov;
 775
 776         /* Step 1: Check header basics */
 777
 778         if (dccp_invalid_packet(skb))
 779                 goto discard_it;
 780
 781         iph = ip_hdr(skb);
 782         /* Step 1: If header checksum is incorrect, drop packet and return */
 783         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 784                 DCCP_WARN("dropped packet with invalid checksum\n");
 785                 goto discard_it;
 786         }
 787
 788         dh = dccp_hdr(skb);
 789
 790         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 791         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 792
 793         dccp_pr_debug("%8.8s "
 794                       "src=%u.%u.%u.%u@%-5d "
 795                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 796                       dccp_packet_name(dh->dccph_type),
 797                       NIPQUAD(iph->saddr), ntohs(dh->dccph_sport),
 798                       NIPQUAD(iph->daddr), ntohs(dh->dccph_dport),
 799                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 800
 801         if (dccp_packet_without_ack(skb)) {
 802                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 803                 dccp_pr_debug_cat("\n");
 804         } else {
 805                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 806                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 807                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 808         }
 809
 810         /* Step 2:
 811          *      Look up flow ID in table and get corresponding socket */
 812         sk = __inet_lookup(&init_net, &dccp_hashinfo,
 813                            iph->saddr, dh->dccph_sport,
 814                            iph->daddr, dh->dccph_dport, inet_iif(skb));
 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 };
 954
 955 static const struct proto_ops inet_dccp_ops = {
 956         .family            = PF_INET,
 957         .owner             = THIS_MODULE,
 958         .release           = inet_release,
 959         .bind              = inet_bind,
 960         .connect           = inet_stream_connect,
 961         .socketpair        = sock_no_socketpair,
 962         .accept            = inet_accept,
 963         .getname           = inet_getname,
 964         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 965         .poll              = dccp_poll,
 966         .ioctl             = inet_ioctl,
 967         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 968         .listen            = inet_dccp_listen,
 969         .shutdown          = inet_shutdown,
 970         .setsockopt        = sock_common_setsockopt,
 971         .getsockopt        = sock_common_getsockopt,
 972         .sendmsg           = inet_sendmsg,
 973         .recvmsg           = sock_common_recvmsg,
 974         .mmap              = sock_no_mmap,
 975         .sendpage          = sock_no_sendpage,
 976 #ifdef CONFIG_COMPAT
 977         .compat_setsockopt = compat_sock_common_setsockopt,
 978         .compat_getsockopt = compat_sock_common_getsockopt,
 979 #endif
 980 };
 981
 982 static struct inet_protosw dccp_v4_protosw = {
 983         .type           = SOCK_DCCP,
 984         .protocol       = IPPROTO_DCCP,
 985         .prot           = &dccp_v4_prot,
 986         .ops            = &inet_dccp_ops,
 987         .capability     = -1,
 988         .no_check       = 0,
 989         .flags          = INET_PROTOSW_ICSK,
 990 };
 991
 992 static int __init dccp_v4_init(void)
 993 {
 994         int err = proto_register(&dccp_v4_prot, 1);
 995
 996         if (err != 0)
 997                 goto out;
 998
 999         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1000         if (err != 0)
1001                 goto out_proto_unregister;
1002
1003         inet_register_protosw(&dccp_v4_protosw);
1004
1005         err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1006                                        SOCK_DCCP, IPPROTO_DCCP);
1007         if (err)
1008                 goto out_unregister_protosw;
1009 out:
1010         return err;
1011 out_unregister_protosw:
1012         inet_unregister_protosw(&dccp_v4_protosw);
1013         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1014 out_proto_unregister:
1015         proto_unregister(&dccp_v4_prot);
1016         goto out;
1017 }
1018
1019 static void __exit dccp_v4_exit(void)
1020 {
1021         inet_unregister_protosw(&dccp_v4_protosw);
1022         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1023         proto_unregister(&dccp_v4_prot);
1024 }
1025
1026 module_init(dccp_v4_init);
1027 module_exit(dccp_v4_exit);
1028
1029 /*
1030  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1031  * values directly, Also cover the case where the protocol is not specified,
1032  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1033  */
1034 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1035 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1036 MODULE_LICENSE("GPL");
1037 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1038 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");