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   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 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
  42 {
  43         return inet_csk_get_port(&dccp_hashinfo, sk, snum,
  44                                  inet_csk_bind_conflict);
  45 }
  46
  47 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  48 {
  49         struct inet_sock *inet = inet_sk(sk);
  50         struct dccp_sock *dp = dccp_sk(sk);
  51         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  52         struct rtable *rt;
  53         __be32 daddr, nexthop;
  54         int tmp;
  55         int err;
  56
  57         dp->dccps_role = DCCP_ROLE_CLIENT;
  58
  59         if (addr_len < sizeof(struct sockaddr_in))
  60                 return -EINVAL;
  61
  62         if (usin->sin_family != AF_INET)
  63                 return -EAFNOSUPPORT;
  64
  65         nexthop = daddr = usin->sin_addr.s_addr;
  66         if (inet->opt != NULL && inet->opt->srr) {
  67                 if (daddr == 0)
  68                         return -EINVAL;
  69                 nexthop = inet->opt->faddr;
  70         }
  71
  72         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
  73                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  74                                IPPROTO_DCCP,
  75                                inet->sport, usin->sin_port, sk);
  76         if (tmp < 0)
  77                 return tmp;
  78
  79         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  80                 ip_rt_put(rt);
  81                 return -ENETUNREACH;
  82         }
  83
  84         if (inet->opt == NULL || !inet->opt->srr)
  85                 daddr = rt->rt_dst;
  86
  87         if (inet->saddr == 0)
  88                 inet->saddr = rt->rt_src;
  89         inet->rcv_saddr = inet->saddr;
  90
  91         inet->dport = usin->sin_port;
  92         inet->daddr = daddr;
  93
  94         inet_csk(sk)->icsk_ext_hdr_len = 0;
  95         if (inet->opt != NULL)
  96                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
  97         /*
  98          * Socket identity is still unknown (sport may be zero).
  99          * However we set state to DCCP_REQUESTING and not releasing socket
 100          * lock select source port, enter ourselves into the hash tables and
 101          * complete initialization after this.
 102          */
 103         dccp_set_state(sk, DCCP_REQUESTING);
 104         err = inet_hash_connect(&dccp_death_row, sk);
 105         if (err != 0)
 106                 goto failure;
 107
 108         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
 109                                 sk);
 110         if (err != 0)
 111                 goto failure;
 112
 113         /* OK, now commit destination to socket.  */
 114         sk_setup_caps(sk, &rt->u.dst);
 115
 116         dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, inet->daddr,
 117                                                     inet->sport, inet->dport);
 118         inet->id = dp->dccps_iss ^ jiffies;
 119
 120         err = dccp_connect(sk);
 121         rt = NULL;
 122         if (err != 0)
 123                 goto failure;
 124 out:
 125         return err;
 126 failure:
 127         /*
 128          * This unhashes the socket and releases the local port, if necessary.
 129          */
 130         dccp_set_state(sk, DCCP_CLOSED);
 131         ip_rt_put(rt);
 132         sk->sk_route_caps = 0;
 133         inet->dport = 0;
 134         goto out;
 135 }
 136
 137 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 138
 139 /*
 140  * This routine does path mtu discovery as defined in RFC1191.
 141  */
 142 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 143                                           const struct iphdr *iph,
 144                                           u32 mtu)
 145 {
 146         struct dst_entry *dst;
 147         const struct inet_sock *inet = inet_sk(sk);
 148         const struct dccp_sock *dp = dccp_sk(sk);
 149
 150         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 151          * send out by Linux are always < 576bytes so they should go through
 152          * unfragmented).
 153          */
 154         if (sk->sk_state == DCCP_LISTEN)
 155                 return;
 156
 157         /* We don't check in the destentry if pmtu discovery is forbidden
 158          * on this route. We just assume that no packet_to_big packets
 159          * are send back when pmtu discovery is not active.
 160          * There is a small race when the user changes this flag in the
 161          * route, but I think that's acceptable.
 162          */
 163         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 164                 return;
 165
 166         dst->ops->update_pmtu(dst, mtu);
 167
 168         /* Something is about to be wrong... Remember soft error
 169          * for the case, if this connection will not able to recover.
 170          */
 171         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 172                 sk->sk_err_soft = EMSGSIZE;
 173
 174         mtu = dst_mtu(dst);
 175
 176         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 177             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 178                 dccp_sync_mss(sk, mtu);
 179
 180                 /*
 181                  * From RFC 4340, sec. 14.1:
 182                  *
 183                  *      DCCP-Sync packets are the best choice for upward
 184                  *      probing, since DCCP-Sync probes do not risk application
 185                  *      data loss.
 186                  */
 187                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 188         } /* else let the usual retransmit timer handle it */
 189 }
 190
 191 /*
 192  * This routine is called by the ICMP module when it gets some sort of error
 193  * condition. If err < 0 then the socket should be closed and the error
 194  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 195  * After adjustment header points to the first 8 bytes of the tcp header. We
 196  * need to find the appropriate port.
 197  *
 198  * The locking strategy used here is very "optimistic". When someone else
 199  * accesses the socket the ICMP is just dropped and for some paths there is no
 200  * check at all. A more general error queue to queue errors for later handling
 201  * is probably better.
 202  */
 203 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 204 {
 205         const struct iphdr *iph = (struct iphdr *)skb->data;
 206         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 207                                                         (iph->ihl << 2));
 208         struct dccp_sock *dp;
 209         struct inet_sock *inet;
 210         const int type = skb->h.icmph->type;
 211         const int code = skb->h.icmph->code;
 212         struct sock *sk;
 213         __u64 seq;
 214         int err;
 215
 216         if (skb->len < (iph->ihl << 2) + 8) {
 217                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 218                 return;
 219         }
 220
 221         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
 222                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 223         if (sk == NULL) {
 224                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 225                 return;
 226         }
 227
 228         if (sk->sk_state == DCCP_TIME_WAIT) {
 229                 inet_twsk_put(inet_twsk(sk));
 230                 return;
 231         }
 232
 233         bh_lock_sock(sk);
 234         /* If too many ICMPs get dropped on busy
 235          * servers this needs to be solved differently.
 236          */
 237         if (sock_owned_by_user(sk))
 238                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 239
 240         if (sk->sk_state == DCCP_CLOSED)
 241                 goto out;
 242
 243         dp = dccp_sk(sk);
 244         seq = dccp_hdr_seq(skb);
 245         if (sk->sk_state != DCCP_LISTEN &&
 246             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 247                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 248                 goto out;
 249         }
 250
 251         switch (type) {
 252         case ICMP_SOURCE_QUENCH:
 253                 /* Just silently ignore these. */
 254                 goto out;
 255         case ICMP_PARAMETERPROB:
 256                 err = EPROTO;
 257                 break;
 258         case ICMP_DEST_UNREACH:
 259                 if (code > NR_ICMP_UNREACH)
 260                         goto out;
 261
 262                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 263                         if (!sock_owned_by_user(sk))
 264                                 dccp_do_pmtu_discovery(sk, iph, info);
 265                         goto out;
 266                 }
 267
 268                 err = icmp_err_convert[code].errno;
 269                 break;
 270         case ICMP_TIME_EXCEEDED:
 271                 err = EHOSTUNREACH;
 272                 break;
 273         default:
 274                 goto out;
 275         }
 276
 277         switch (sk->sk_state) {
 278                 struct request_sock *req , **prev;
 279         case DCCP_LISTEN:
 280                 if (sock_owned_by_user(sk))
 281                         goto out;
 282                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 283                                           iph->daddr, iph->saddr);
 284                 if (!req)
 285                         goto out;
 286
 287                 /*
 288                  * ICMPs are not backlogged, hence we cannot get an established
 289                  * socket here.
 290                  */
 291                 BUG_TRAP(!req->sk);
 292
 293                 if (seq != dccp_rsk(req)->dreq_iss) {
 294                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 295                         goto out;
 296                 }
 297                 /*
 298                  * Still in RESPOND, just remove it silently.
 299                  * There is no good way to pass the error to the newly
 300                  * created socket, and POSIX does not want network
 301                  * errors returned from accept().
 302                  */
 303                 inet_csk_reqsk_queue_drop(sk, req, prev);
 304                 goto out;
 305
 306         case DCCP_REQUESTING:
 307         case DCCP_RESPOND:
 308                 if (!sock_owned_by_user(sk)) {
 309                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 310                         sk->sk_err = err;
 311
 312                         sk->sk_error_report(sk);
 313
 314                         dccp_done(sk);
 315                 } else
 316                         sk->sk_err_soft = err;
 317                 goto out;
 318         }
 319
 320         /* If we've already connected we will keep trying
 321          * until we time out, or the user gives up.
 322          *
 323          * rfc1122 4.2.3.9 allows to consider as hard errors
 324          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 325          * but it is obsoleted by pmtu discovery).
 326          *
 327          * Note, that in modern internet, where routing is unreliable
 328          * and in each dark corner broken firewalls sit, sending random
 329          * errors ordered by their masters even this two messages finally lose
 330          * their original sense (even Linux sends invalid PORT_UNREACHs)
 331          *
 332          * Now we are in compliance with RFCs.
 333          *                                                      --ANK (980905)
 334          */
 335
 336         inet = inet_sk(sk);
 337         if (!sock_owned_by_user(sk) && inet->recverr) {
 338                 sk->sk_err = err;
 339                 sk->sk_error_report(sk);
 340         } else /* Only an error on timeout */
 341                 sk->sk_err_soft = err;
 342 out:
 343         bh_unlock_sock(sk);
 344         sock_put(sk);
 345 }
 346
 347 static inline u16 dccp_v4_csum_finish(struct sk_buff *skb,
 348                                       __be32 src, __be32 dst)
 349 {
 350         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 351 }
 352
 353 void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
 354 {
 355         const struct inet_sock *inet = inet_sk(sk);
 356         struct dccp_hdr *dh = dccp_hdr(skb);
 357
 358         dccp_csum_outgoing(skb);
 359         dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
 360 }
 361
 362 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 363
 364 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 365 {
 366         return secure_dccp_sequence_number(skb->nh.iph->daddr,
 367                                            skb->nh.iph->saddr,
 368                                            dccp_hdr(skb)->dccph_dport,
 369                                            dccp_hdr(skb)->dccph_sport);
 370 }
 371
 372 /*
 373  * The three way handshake has completed - we got a valid ACK or DATAACK -
 374  * now create the new socket.
 375  *
 376  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 377  */
 378 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 379                                        struct request_sock *req,
 380                                        struct dst_entry *dst)
 381 {
 382         struct inet_request_sock *ireq;
 383         struct inet_sock *newinet;
 384         struct dccp_sock *newdp;
 385         struct sock *newsk;
 386
 387         if (sk_acceptq_is_full(sk))
 388                 goto exit_overflow;
 389
 390         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 391                 goto exit;
 392
 393         newsk = dccp_create_openreq_child(sk, req, skb);
 394         if (newsk == NULL)
 395                 goto exit;
 396
 397         sk_setup_caps(newsk, dst);
 398
 399         newdp              = dccp_sk(newsk);
 400         newinet            = inet_sk(newsk);
 401         ireq               = inet_rsk(req);
 402         newinet->daddr     = ireq->rmt_addr;
 403         newinet->rcv_saddr = ireq->loc_addr;
 404         newinet->saddr     = ireq->loc_addr;
 405         newinet->opt       = ireq->opt;
 406         ireq->opt          = NULL;
 407         newinet->mc_index  = inet_iif(skb);
 408         newinet->mc_ttl    = skb->nh.iph->ttl;
 409         newinet->id        = jiffies;
 410
 411         dccp_sync_mss(newsk, dst_mtu(dst));
 412
 413         __inet_hash(&dccp_hashinfo, newsk, 0);
 414         __inet_inherit_port(&dccp_hashinfo, sk, newsk);
 415
 416         return newsk;
 417
 418 exit_overflow:
 419         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
 420 exit:
 421         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
 422         dst_release(dst);
 423         return NULL;
 424 }
 425
 426 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 427
 428 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 429 {
 430         const struct dccp_hdr *dh = dccp_hdr(skb);
 431         const struct iphdr *iph = skb->nh.iph;
 432         struct sock *nsk;
 433         struct request_sock **prev;
 434         /* Find possible connection requests. */
 435         struct request_sock *req = inet_csk_search_req(sk, &prev,
 436                                                        dh->dccph_sport,
 437                                                        iph->saddr, iph->daddr);
 438         if (req != NULL)
 439                 return dccp_check_req(sk, skb, req, prev);
 440
 441         nsk = inet_lookup_established(&dccp_hashinfo,
 442                                       iph->saddr, dh->dccph_sport,
 443                                       iph->daddr, dh->dccph_dport,
 444                                       inet_iif(skb));
 445         if (nsk != NULL) {
 446                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 447                         bh_lock_sock(nsk);
 448                         return nsk;
 449                 }
 450                 inet_twsk_put(inet_twsk(nsk));
 451                 return NULL;
 452         }
 453
 454         return sk;
 455 }
 456
 457 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
 458                                            struct sk_buff *skb)
 459 {
 460         struct rtable *rt;
 461         struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
 462                             .nl_u = { .ip4_u =
 463                                       { .daddr = skb->nh.iph->saddr,
 464                                         .saddr = skb->nh.iph->daddr,
 465                                         .tos = RT_CONN_FLAGS(sk) } },
 466                             .proto = sk->sk_protocol,
 467                             .uli_u = { .ports =
 468                                        { .sport = dccp_hdr(skb)->dccph_dport,
 469                                          .dport = dccp_hdr(skb)->dccph_sport }
 470                                      }
 471                           };
 472
 473         security_skb_classify_flow(skb, &fl);
 474         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 475                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 476                 return NULL;
 477         }
 478
 479         return &rt->u.dst;
 480 }
 481
 482 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 483                                  struct dst_entry *dst)
 484 {
 485         int err = -1;
 486         struct sk_buff *skb;
 487
 488         /* First, grab a route. */
 489
 490         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 491                 goto out;
 492
 493         skb = dccp_make_response(sk, dst, req);
 494         if (skb != NULL) {
 495                 const struct inet_request_sock *ireq = inet_rsk(req);
 496                 struct dccp_hdr *dh = dccp_hdr(skb);
 497
 498                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
 499                                                               ireq->rmt_addr);
 500                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 501                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 502                                             ireq->rmt_addr,
 503                                             ireq->opt);
 504                 err = net_xmit_eval(err);
 505         }
 506
 507 out:
 508         dst_release(dst);
 509         return err;
 510 }
 511
 512 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
 513 {
 514         int err;
 515         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 516         const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
 517                                        sizeof(struct dccp_hdr_ext) +
 518                                        sizeof(struct dccp_hdr_reset);
 519         struct sk_buff *skb;
 520         struct dst_entry *dst;
 521         u64 seqno = 0;
 522
 523         /* Never send a reset in response to a reset. */
 524         if (rxdh->dccph_type == DCCP_PKT_RESET)
 525                 return;
 526
 527         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 528                 return;
 529
 530         dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
 531         if (dst == NULL)
 532                 return;
 533
 534         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header,
 535                         GFP_ATOMIC);
 536         if (skb == NULL)
 537                 goto out;
 538
 539         /* Reserve space for headers. */
 540         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 541         skb->dst = dst_clone(dst);
 542
 543         dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
 544
 545         /* Build DCCP header and checksum it. */
 546         dh->dccph_type     = DCCP_PKT_RESET;
 547         dh->dccph_sport    = rxdh->dccph_dport;
 548         dh->dccph_dport    = rxdh->dccph_sport;
 549         dh->dccph_doff     = dccp_hdr_reset_len / 4;
 550         dh->dccph_x        = 1;
 551         dccp_hdr_reset(skb)->dccph_reset_code =
 552                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 553
 554         /* See "8.3.1. Abnormal Termination" in RFC 4340 */
 555         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 556                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 557
 558         dccp_hdr_set_seq(dh, seqno);
 559         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
 560
 561         dccp_csum_outgoing(skb);
 562         dh->dccph_checksum = dccp_v4_csum_finish(skb, rxskb->nh.iph->saddr,
 563                                                       rxskb->nh.iph->daddr);
 564
 565         bh_lock_sock(dccp_v4_ctl_socket->sk);
 566         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 567                                     rxskb->nh.iph->daddr,
 568                                     rxskb->nh.iph->saddr, NULL);
 569         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 570
 571         if (net_xmit_eval(err) == 0) {
 572                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 573                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 574         }
 575 out:
 576          dst_release(dst);
 577 }
 578
 579 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 580 {
 581         kfree(inet_rsk(req)->opt);
 582 }
 583
 584 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 585         .family         = PF_INET,
 586         .obj_size       = sizeof(struct dccp_request_sock),
 587         .rtx_syn_ack    = dccp_v4_send_response,
 588         .send_ack       = dccp_reqsk_send_ack,
 589         .destructor     = dccp_v4_reqsk_destructor,
 590         .send_reset     = dccp_v4_ctl_send_reset,
 591 };
 592
 593 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 594 {
 595         struct inet_request_sock *ireq;
 596         struct request_sock *req;
 597         struct dccp_request_sock *dreq;
 598         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 599         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 600         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
 601
 602         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 603         if (((struct rtable *)skb->dst)->rt_flags &
 604             (RTCF_BROADCAST | RTCF_MULTICAST)) {
 605                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 606                 goto drop;
 607         }
 608
 609         if (dccp_bad_service_code(sk, service)) {
 610                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 611                 goto drop;
 612         }
 613         /*
 614          * TW buckets are converted to open requests without
 615          * limitations, they conserve resources and peer is
 616          * evidently real one.
 617          */
 618         if (inet_csk_reqsk_queue_is_full(sk))
 619                 goto drop;
 620
 621         /*
 622          * Accept backlog is full. If we have already queued enough
 623          * of warm entries in syn queue, drop request. It is better than
 624          * clogging syn queue with openreqs with exponentially increasing
 625          * timeout.
 626          */
 627         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 628                 goto drop;
 629
 630         req = reqsk_alloc(&dccp_request_sock_ops);
 631         if (req == NULL)
 632                 goto drop;
 633
 634         if (dccp_parse_options(sk, skb))
 635                 goto drop_and_free;
 636
 637         dccp_reqsk_init(req, skb);
 638
 639         if (security_inet_conn_request(sk, skb, req))
 640                 goto drop_and_free;
 641
 642         ireq = inet_rsk(req);
 643         ireq->loc_addr = skb->nh.iph->daddr;
 644         ireq->rmt_addr = skb->nh.iph->saddr;
 645         ireq->opt       = NULL;
 646
 647         /*
 648          * Step 3: Process LISTEN state
 649          *
 650          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 651          *
 652          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 653          * dccp_create_openreq_child.
 654          */
 655         dreq = dccp_rsk(req);
 656         dreq->dreq_isr     = dcb->dccpd_seq;
 657         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 658         dreq->dreq_service = service;
 659
 660         if (dccp_v4_send_response(sk, req, NULL))
 661                 goto drop_and_free;
 662
 663         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 664         return 0;
 665
 666 drop_and_free:
 667         reqsk_free(req);
 668 drop:
 669         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 670         dcb->dccpd_reset_code = reset_code;
 671         return -1;
 672 }
 673
 674 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 675
 676 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 677 {
 678         struct dccp_hdr *dh = dccp_hdr(skb);
 679
 680         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 681                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 682                         goto reset;
 683                 return 0;
 684         }
 685
 686         /*
 687          *  Step 3: Process LISTEN state
 688          *       If P.type == Request or P contains a valid Init Cookie option,
 689          *            (* Must scan the packet's options to check for Init
 690          *               Cookies.  Only Init Cookies are processed here,
 691          *               however; other options are processed in Step 8.  This
 692          *               scan need only be performed if the endpoint uses Init
 693          *               Cookies *)
 694          *            (* Generate a new socket and switch to that socket *)
 695          *            Set S := new socket for this port pair
 696          *            S.state = RESPOND
 697          *            Choose S.ISS (initial seqno) or set from Init Cookies
 698          *            Initialize S.GAR := S.ISS
 699          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 700          *            Continue with S.state == RESPOND
 701          *            (* A Response packet will be generated in Step 11 *)
 702          *       Otherwise,
 703          *            Generate Reset(No Connection) unless P.type == Reset
 704          *            Drop packet and return
 705          *
 706          * NOTE: the check for the packet types is done in
 707          *       dccp_rcv_state_process
 708          */
 709         if (sk->sk_state == DCCP_LISTEN) {
 710                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 711
 712                 if (nsk == NULL)
 713                         goto discard;
 714
 715                 if (nsk != sk) {
 716                         if (dccp_child_process(sk, nsk, skb))
 717                                 goto reset;
 718                         return 0;
 719                 }
 720         }
 721
 722         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 723                 goto reset;
 724         return 0;
 725
 726 reset:
 727         dccp_v4_ctl_send_reset(sk, skb);
 728 discard:
 729         kfree_skb(skb);
 730         return 0;
 731 }
 732
 733 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 734
 735 /**
 736  *      dccp_invalid_packet  -  check for malformed packets
 737  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 738  *      Packets that fail these checks are ignored and do not receive Resets.
 739  */
 740 int dccp_invalid_packet(struct sk_buff *skb)
 741 {
 742         const struct dccp_hdr *dh;
 743         unsigned int cscov;
 744
 745         if (skb->pkt_type != PACKET_HOST)
 746                 return 1;
 747
 748         /* If the packet is shorter than 12 bytes, drop packet and return */
 749         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 750                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
 751                 return 1;
 752         }
 753
 754         dh = dccp_hdr(skb);
 755
 756         /* If P.type is not understood, drop packet and return */
 757         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 758                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
 759                 return 1;
 760         }
 761
 762         /*
 763          * If P.Data Offset is too small for packet type, drop packet and return
 764          */
 765         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 766                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 767                                             "too small\n", dh->dccph_doff);
 768                 return 1;
 769         }
 770         /*
 771          * If P.Data Offset is too too large for packet, drop packet and return
 772          */
 773         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 774                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 775                                             "too large\n", dh->dccph_doff);
 776                 return 1;
 777         }
 778
 779         /*
 780          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 781          * has short sequence numbers), drop packet and return
 782          */
 783         if (dh->dccph_type >= DCCP_PKT_DATA    &&
 784             dh->dccph_type <= DCCP_PKT_DATAACK && dh->dccph_x == 0)  {
 785                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data||Ack||"
 786                                             "DataAck, while P.X == 0\n",
 787                                dccp_packet_name(dh->dccph_type));
 788                 return 1;
 789         }
 790
 791         /*
 792          * If P.CsCov is too large for the packet size, drop packet and return.
 793          * This must come _before_ checksumming (not as RFC 4340 suggests).
 794          */
 795         cscov = dccp_csum_coverage(skb);
 796         if (cscov > skb->len) {
 797                 LIMIT_NETDEBUG(KERN_WARNING
 798                                "DCCP: P.CsCov %u exceeds packet length %d\n",
 799                                dh->dccph_cscov, skb->len);
 800                 return 1;
 801         }
 802
 803         /* If header checksum is incorrect, drop packet and return.
 804          * (This step is completed in the AF-dependent functions.) */
 805         skb->csum = skb_checksum(skb, 0, cscov, 0);
 806
 807         return 0;
 808 }
 809
 810 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 811
 812 /* this is called when real data arrives */
 813 static int dccp_v4_rcv(struct sk_buff *skb)
 814 {
 815         const struct dccp_hdr *dh;
 816         struct sock *sk;
 817         int min_cov;
 818
 819         /* Step 1: Check header basics */
 820
 821         if (dccp_invalid_packet(skb))
 822                 goto discard_it;
 823
 824         /* Step 1: If header checksum is incorrect, drop packet and return */
 825         if (dccp_v4_csum_finish(skb, skb->nh.iph->saddr, skb->nh.iph->daddr)) {
 826                 LIMIT_NETDEBUG(KERN_WARNING
 827                                "%s: dropped packet with invalid checksum\n",
 828                                __FUNCTION__);
 829                 goto discard_it;
 830         }
 831
 832         dh = dccp_hdr(skb);
 833
 834         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
 835         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 836
 837         dccp_pr_debug("%8.8s "
 838                       "src=%u.%u.%u.%u@%-5d "
 839                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 840                       dccp_packet_name(dh->dccph_type),
 841                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
 842                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
 843                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 844
 845         if (dccp_packet_without_ack(skb)) {
 846                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 847                 dccp_pr_debug_cat("\n");
 848         } else {
 849                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 850                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 851                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 852         }
 853
 854         /* Step 2:
 855          *      Look up flow ID in table and get corresponding socket */
 856         sk = __inet_lookup(&dccp_hashinfo,
 857                            skb->nh.iph->saddr, dh->dccph_sport,
 858                            skb->nh.iph->daddr, dh->dccph_dport,
 859                            inet_iif(skb));
 860
 861         /*
 862          * Step 2:
 863          *      If no socket ...
 864          */
 865         if (sk == NULL) {
 866                 dccp_pr_debug("failed to look up flow ID in table and "
 867                               "get corresponding socket\n");
 868                 goto no_dccp_socket;
 869         }
 870
 871         /*
 872          * Step 2:
 873          *      ... or S.state == TIMEWAIT,
 874          *              Generate Reset(No Connection) unless P.type == Reset
 875          *              Drop packet and return
 876          */
 877         if (sk->sk_state == DCCP_TIME_WAIT) {
 878                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 879                 inet_twsk_put(inet_twsk(sk));
 880                 goto no_dccp_socket;
 881         }
 882
 883         /*
 884          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 885          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 886          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 887          */
 888         min_cov = dccp_sk(sk)->dccps_pcrlen;
 889         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 890                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 891                               dh->dccph_cscov, min_cov);
 892                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 893                  *         options (Section 11.7) with Drop Code 0, Protocol
 894                  *         Constraints."                                     */
 895                 goto discard_and_relse;
 896         }
 897
 898         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 899                 goto discard_and_relse;
 900         nf_reset(skb);
 901
 902         return sk_receive_skb(sk, skb);
 903
 904 no_dccp_socket:
 905         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 906                 goto discard_it;
 907         /*
 908          * Step 2:
 909          *      If no socket ...
 910          *              Generate Reset(No Connection) unless P.type == Reset
 911          *              Drop packet and return
 912          */
 913         if (dh->dccph_type != DCCP_PKT_RESET) {
 914                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 915                                         DCCP_RESET_CODE_NO_CONNECTION;
 916                 dccp_v4_ctl_send_reset(sk, skb);
 917         }
 918
 919 discard_it:
 920         kfree_skb(skb);
 921         return 0;
 922
 923 discard_and_relse:
 924         sock_put(sk);
 925         goto discard_it;
 926 }
 927
 928 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 929         .queue_xmit        = ip_queue_xmit,
 930         .send_check        = dccp_v4_send_check,
 931         .rebuild_header    = inet_sk_rebuild_header,
 932         .conn_request      = dccp_v4_conn_request,
 933         .syn_recv_sock     = dccp_v4_request_recv_sock,
 934         .net_header_len    = sizeof(struct iphdr),
 935         .setsockopt        = ip_setsockopt,
 936         .getsockopt        = ip_getsockopt,
 937         .addr2sockaddr     = inet_csk_addr2sockaddr,
 938         .sockaddr_len      = sizeof(struct sockaddr_in),
 939 #ifdef CONFIG_COMPAT
 940         .compat_setsockopt = compat_ip_setsockopt,
 941         .compat_getsockopt = compat_ip_getsockopt,
 942 #endif
 943 };
 944
 945 static int dccp_v4_init_sock(struct sock *sk)
 946 {
 947         static __u8 dccp_v4_ctl_sock_initialized;
 948         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 949
 950         if (err == 0) {
 951                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 952                         dccp_v4_ctl_sock_initialized = 1;
 953                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 954         }
 955
 956         return err;
 957 }
 958
 959 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 960         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 961 };
 962
 963 static struct proto dccp_v4_prot = {
 964         .name                   = "DCCP",
 965         .owner                  = THIS_MODULE,
 966         .close                  = dccp_close,
 967         .connect                = dccp_v4_connect,
 968         .disconnect             = dccp_disconnect,
 969         .ioctl                  = dccp_ioctl,
 970         .init                   = dccp_v4_init_sock,
 971         .setsockopt             = dccp_setsockopt,
 972         .getsockopt             = dccp_getsockopt,
 973         .sendmsg                = dccp_sendmsg,
 974         .recvmsg                = dccp_recvmsg,
 975         .backlog_rcv            = dccp_v4_do_rcv,
 976         .hash                   = dccp_hash,
 977         .unhash                 = dccp_unhash,
 978         .accept                 = inet_csk_accept,
 979         .get_port               = dccp_v4_get_port,
 980         .shutdown               = dccp_shutdown,
 981         .destroy                = dccp_destroy_sock,
 982         .orphan_count           = &dccp_orphan_count,
 983         .max_header             = MAX_DCCP_HEADER,
 984         .obj_size               = sizeof(struct dccp_sock),
 985         .rsk_prot               = &dccp_request_sock_ops,
 986         .twsk_prot              = &dccp_timewait_sock_ops,
 987 #ifdef CONFIG_COMPAT
 988         .compat_setsockopt      = compat_dccp_setsockopt,
 989         .compat_getsockopt      = compat_dccp_getsockopt,
 990 #endif
 991 };
 992
 993 static struct net_protocol dccp_v4_protocol = {
 994         .handler        = dccp_v4_rcv,
 995         .err_handler    = dccp_v4_err,
 996         .no_policy      = 1,
 997 };
 998
 999 static const struct proto_ops inet_dccp_ops = {
1000         .family            = PF_INET,
1001         .owner             = THIS_MODULE,
1002         .release           = inet_release,
1003         .bind              = inet_bind,
1004         .connect           = inet_stream_connect,
1005         .socketpair        = sock_no_socketpair,
1006         .accept            = inet_accept,
1007         .getname           = inet_getname,
1008         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1009         .poll              = dccp_poll,
1010         .ioctl             = inet_ioctl,
1011         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1012         .listen            = inet_dccp_listen,
1013         .shutdown          = inet_shutdown,
1014         .setsockopt        = sock_common_setsockopt,
1015         .getsockopt        = sock_common_getsockopt,
1016         .sendmsg           = inet_sendmsg,
1017         .recvmsg           = sock_common_recvmsg,
1018         .mmap              = sock_no_mmap,
1019         .sendpage          = sock_no_sendpage,
1020 #ifdef CONFIG_COMPAT
1021         .compat_setsockopt = compat_sock_common_setsockopt,
1022         .compat_getsockopt = compat_sock_common_getsockopt,
1023 #endif
1024 };
1025
1026 static struct inet_protosw dccp_v4_protosw = {
1027         .type           = SOCK_DCCP,
1028         .protocol       = IPPROTO_DCCP,
1029         .prot           = &dccp_v4_prot,
1030         .ops            = &inet_dccp_ops,
1031         .capability     = -1,
1032         .no_check       = 0,
1033         .flags          = INET_PROTOSW_ICSK,
1034 };
1035
1036 static int __init dccp_v4_init(void)
1037 {
1038         int err = proto_register(&dccp_v4_prot, 1);
1039
1040         if (err != 0)
1041                 goto out;
1042
1043         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1044         if (err != 0)
1045                 goto out_proto_unregister;
1046
1047         inet_register_protosw(&dccp_v4_protosw);
1048
1049         err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1050                                        SOCK_DCCP, IPPROTO_DCCP);
1051         if (err)
1052                 goto out_unregister_protosw;
1053 out:
1054         return err;
1055 out_unregister_protosw:
1056         inet_unregister_protosw(&dccp_v4_protosw);
1057         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1058 out_proto_unregister:
1059         proto_unregister(&dccp_v4_prot);
1060         goto out;
1061 }
1062
1063 static void __exit dccp_v4_exit(void)
1064 {
1065         inet_unregister_protosw(&dccp_v4_protosw);
1066         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1067         proto_unregister(&dccp_v4_prot);
1068 }
1069
1070 module_init(dccp_v4_init);
1071 module_exit(dccp_v4_exit);
1072
1073 /*
1074  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1075  * values directly, Also cover the case where the protocol is not specified,
1076  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1077  */
1078 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
1079 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
1080 MODULE_LICENSE("GPL");
1081 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1082 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");