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 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_gar =
 117                 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
 118                                                             inet->daddr,
 119                                                             inet->sport,
 120                                                             usin->sin_port);
 121         dccp_update_gss(sk, dp->dccps_iss);
 122
 123         inet->id = dp->dccps_iss ^ jiffies;
 124
 125         err = dccp_connect(sk);
 126         rt = NULL;
 127         if (err != 0)
 128                 goto failure;
 129 out:
 130         return err;
 131 failure:
 132         /*
 133          * This unhashes the socket and releases the local port, if necessary.
 134          */
 135         dccp_set_state(sk, DCCP_CLOSED);
 136         ip_rt_put(rt);
 137         sk->sk_route_caps = 0;
 138         inet->dport = 0;
 139         goto out;
 140 }
 141
 142 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 143
 144 /*
 145  * This routine does path mtu discovery as defined in RFC1191.
 146  */
 147 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 148                                           const struct iphdr *iph,
 149                                           u32 mtu)
 150 {
 151         struct dst_entry *dst;
 152         const struct inet_sock *inet = inet_sk(sk);
 153         const struct dccp_sock *dp = dccp_sk(sk);
 154
 155         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 156          * send out by Linux are always < 576bytes so they should go through
 157          * unfragmented).
 158          */
 159         if (sk->sk_state == DCCP_LISTEN)
 160                 return;
 161
 162         /* We don't check in the destentry if pmtu discovery is forbidden
 163          * on this route. We just assume that no packet_to_big packets
 164          * are send back when pmtu discovery is not active.
 165          * There is a small race when the user changes this flag in the
 166          * route, but I think that's acceptable.
 167          */
 168         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 169                 return;
 170
 171         dst->ops->update_pmtu(dst, mtu);
 172
 173         /* Something is about to be wrong... Remember soft error
 174          * for the case, if this connection will not able to recover.
 175          */
 176         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 177                 sk->sk_err_soft = EMSGSIZE;
 178
 179         mtu = dst_mtu(dst);
 180
 181         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 182             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 183                 dccp_sync_mss(sk, mtu);
 184
 185                 /*
 186                  * From RFC 4340, sec. 14.1:
 187                  *
 188                  *      DCCP-Sync packets are the best choice for upward
 189                  *      probing, since DCCP-Sync probes do not risk application
 190                  *      data loss.
 191                  */
 192                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 193         } /* else let the usual retransmit timer handle it */
 194 }
 195
 196 static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
 197                                    struct request_sock *req)
 198 {
 199         int err;
 200         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 201         const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
 202                                      sizeof(struct dccp_hdr_ext) +
 203                                      sizeof(struct dccp_hdr_ack_bits);
 204         struct sk_buff *skb;
 205
 206         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 207                 return;
 208
 209         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
 210         if (skb == NULL)
 211                 return;
 212
 213         /* Reserve space for headers. */
 214         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 215
 216         skb->dst = dst_clone(rxskb->dst);
 217
 218         skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
 219         dh = dccp_hdr(skb);
 220         memset(dh, 0, dccp_hdr_ack_len);
 221
 222         /* Build DCCP header and checksum it. */
 223         dh->dccph_type     = DCCP_PKT_ACK;
 224         dh->dccph_sport    = rxdh->dccph_dport;
 225         dh->dccph_dport    = rxdh->dccph_sport;
 226         dh->dccph_doff     = dccp_hdr_ack_len / 4;
 227         dh->dccph_x        = 1;
 228
 229         dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
 230         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 231                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 232
 233         bh_lock_sock(dccp_v4_ctl_socket->sk);
 234         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 235                                     rxskb->nh.iph->daddr,
 236                                     rxskb->nh.iph->saddr, NULL);
 237         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 238
 239         if (err == NET_XMIT_CN || err == 0) {
 240                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 241                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 242         }
 243 }
 244
 245 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 246                                  struct dst_entry *dst)
 247 {
 248         int err = -1;
 249         struct sk_buff *skb;
 250
 251         /* First, grab a route. */
 252
 253         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 254                 goto out;
 255
 256         skb = dccp_make_response(sk, dst, req);
 257         if (skb != NULL) {
 258                 const struct inet_request_sock *ireq = inet_rsk(req);
 259                 struct dccp_hdr *dh = dccp_hdr(skb);
 260
 261                 dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
 262                                                       ireq->rmt_addr);
 263                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 264                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 265                                             ireq->rmt_addr,
 266                                             ireq->opt);
 267                 if (err == NET_XMIT_CN)
 268                         err = 0;
 269         }
 270
 271 out:
 272         dst_release(dst);
 273         return err;
 274 }
 275
 276 /*
 277  * This routine is called by the ICMP module when it gets some sort of error
 278  * condition. If err < 0 then the socket should be closed and the error
 279  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 280  * After adjustment header points to the first 8 bytes of the tcp header. We
 281  * need to find the appropriate port.
 282  *
 283  * The locking strategy used here is very "optimistic". When someone else
 284  * accesses the socket the ICMP is just dropped and for some paths there is no
 285  * check at all. A more general error queue to queue errors for later handling
 286  * is probably better.
 287  */
 288 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 289 {
 290         const struct iphdr *iph = (struct iphdr *)skb->data;
 291         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 292                                                         (iph->ihl << 2));
 293         struct dccp_sock *dp;
 294         struct inet_sock *inet;
 295         const int type = skb->h.icmph->type;
 296         const int code = skb->h.icmph->code;
 297         struct sock *sk;
 298         __u64 seq;
 299         int err;
 300
 301         if (skb->len < (iph->ihl << 2) + 8) {
 302                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 303                 return;
 304         }
 305
 306         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
 307                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 308         if (sk == NULL) {
 309                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 310                 return;
 311         }
 312
 313         if (sk->sk_state == DCCP_TIME_WAIT) {
 314                 inet_twsk_put(inet_twsk(sk));
 315                 return;
 316         }
 317
 318         bh_lock_sock(sk);
 319         /* If too many ICMPs get dropped on busy
 320          * servers this needs to be solved differently.
 321          */
 322         if (sock_owned_by_user(sk))
 323                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 324
 325         if (sk->sk_state == DCCP_CLOSED)
 326                 goto out;
 327
 328         dp = dccp_sk(sk);
 329         seq = dccp_hdr_seq(skb);
 330         if (sk->sk_state != DCCP_LISTEN &&
 331             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 332                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 333                 goto out;
 334         }
 335
 336         switch (type) {
 337         case ICMP_SOURCE_QUENCH:
 338                 /* Just silently ignore these. */
 339                 goto out;
 340         case ICMP_PARAMETERPROB:
 341                 err = EPROTO;
 342                 break;
 343         case ICMP_DEST_UNREACH:
 344                 if (code > NR_ICMP_UNREACH)
 345                         goto out;
 346
 347                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 348                         if (!sock_owned_by_user(sk))
 349                                 dccp_do_pmtu_discovery(sk, iph, info);
 350                         goto out;
 351                 }
 352
 353                 err = icmp_err_convert[code].errno;
 354                 break;
 355         case ICMP_TIME_EXCEEDED:
 356                 err = EHOSTUNREACH;
 357                 break;
 358         default:
 359                 goto out;
 360         }
 361
 362         switch (sk->sk_state) {
 363                 struct request_sock *req , **prev;
 364         case DCCP_LISTEN:
 365                 if (sock_owned_by_user(sk))
 366                         goto out;
 367                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 368                                           iph->daddr, iph->saddr);
 369                 if (!req)
 370                         goto out;
 371
 372                 /*
 373                  * ICMPs are not backlogged, hence we cannot get an established
 374                  * socket here.
 375                  */
 376                 BUG_TRAP(!req->sk);
 377
 378                 if (seq != dccp_rsk(req)->dreq_iss) {
 379                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 380                         goto out;
 381                 }
 382                 /*
 383                  * Still in RESPOND, just remove it silently.
 384                  * There is no good way to pass the error to the newly
 385                  * created socket, and POSIX does not want network
 386                  * errors returned from accept().
 387                  */
 388                 inet_csk_reqsk_queue_drop(sk, req, prev);
 389                 goto out;
 390
 391         case DCCP_REQUESTING:
 392         case DCCP_RESPOND:
 393                 if (!sock_owned_by_user(sk)) {
 394                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 395                         sk->sk_err = err;
 396
 397                         sk->sk_error_report(sk);
 398
 399                         dccp_done(sk);
 400                 } else
 401                         sk->sk_err_soft = err;
 402                 goto out;
 403         }
 404
 405         /* If we've already connected we will keep trying
 406          * until we time out, or the user gives up.
 407          *
 408          * rfc1122 4.2.3.9 allows to consider as hard errors
 409          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 410          * but it is obsoleted by pmtu discovery).
 411          *
 412          * Note, that in modern internet, where routing is unreliable
 413          * and in each dark corner broken firewalls sit, sending random
 414          * errors ordered by their masters even this two messages finally lose
 415          * their original sense (even Linux sends invalid PORT_UNREACHs)
 416          *
 417          * Now we are in compliance with RFCs.
 418          *                                                      --ANK (980905)
 419          */
 420
 421         inet = inet_sk(sk);
 422         if (!sock_owned_by_user(sk) && inet->recverr) {
 423                 sk->sk_err = err;
 424                 sk->sk_error_report(sk);
 425         } else /* Only an error on timeout */
 426                 sk->sk_err_soft = err;
 427 out:
 428         bh_unlock_sock(sk);
 429         sock_put(sk);
 430 }
 431
 432 /* This routine computes an IPv4 DCCP checksum. */
 433 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
 434 {
 435         const struct inet_sock *inet = inet_sk(sk);
 436         struct dccp_hdr *dh = dccp_hdr(skb);
 437
 438         dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
 439 }
 440
 441 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 442
 443 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
 444                                         const struct sk_buff *skb)
 445 {
 446         return secure_dccp_sequence_number(skb->nh.iph->daddr,
 447                                            skb->nh.iph->saddr,
 448                                            dccp_hdr(skb)->dccph_dport,
 449                                            dccp_hdr(skb)->dccph_sport);
 450 }
 451
 452 static struct request_sock_ops dccp_request_sock_ops;
 453
 454 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 455 {
 456         struct inet_request_sock *ireq;
 457         struct dccp_sock dp;
 458         struct request_sock *req;
 459         struct dccp_request_sock *dreq;
 460         const __be32 saddr = skb->nh.iph->saddr;
 461         const __be32 daddr = skb->nh.iph->daddr;
 462         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 463         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 464         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
 465
 466         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 467         if (((struct rtable *)skb->dst)->rt_flags &
 468             (RTCF_BROADCAST | RTCF_MULTICAST)) {
 469                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 470                 goto drop;
 471         }
 472
 473         if (dccp_bad_service_code(sk, service)) {
 474                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 475                 goto drop;
 476         }
 477         /*
 478          * TW buckets are converted to open requests without
 479          * limitations, they conserve resources and peer is
 480          * evidently real one.
 481          */
 482         if (inet_csk_reqsk_queue_is_full(sk))
 483                 goto drop;
 484
 485         /*
 486          * Accept backlog is full. If we have already queued enough
 487          * of warm entries in syn queue, drop request. It is better than
 488          * clogging syn queue with openreqs with exponentially increasing
 489          * timeout.
 490          */
 491         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 492                 goto drop;
 493
 494         req = reqsk_alloc(&dccp_request_sock_ops);
 495         if (req == NULL)
 496                 goto drop;
 497
 498         if (dccp_parse_options(sk, skb))
 499                 goto drop_and_free;
 500
 501         dccp_openreq_init(req, &dp, skb);
 502
 503         if (security_inet_conn_request(sk, skb, req))
 504                 goto drop_and_free;
 505
 506         ireq = inet_rsk(req);
 507         ireq->loc_addr = daddr;
 508         ireq->rmt_addr = saddr;
 509         req->rcv_wnd    = dccp_feat_default_sequence_window;
 510         ireq->opt       = NULL;
 511
 512         /*
 513          * Step 3: Process LISTEN state
 514          *
 515          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 516          *
 517          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 518          * dccp_create_openreq_child.
 519          */
 520         dreq = dccp_rsk(req);
 521         dreq->dreq_isr     = dcb->dccpd_seq;
 522         dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
 523         dreq->dreq_service = service;
 524
 525         if (dccp_v4_send_response(sk, req, NULL))
 526                 goto drop_and_free;
 527
 528         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 529         return 0;
 530
 531 drop_and_free:
 532         reqsk_free(req);
 533 drop:
 534         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 535         dcb->dccpd_reset_code = reset_code;
 536         return -1;
 537 }
 538
 539 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 540
 541 /*
 542  * The three way handshake has completed - we got a valid ACK or DATAACK -
 543  * now create the new socket.
 544  *
 545  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 546  */
 547 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 548                                        struct request_sock *req,
 549                                        struct dst_entry *dst)
 550 {
 551         struct inet_request_sock *ireq;
 552         struct inet_sock *newinet;
 553         struct dccp_sock *newdp;
 554         struct sock *newsk;
 555
 556         if (sk_acceptq_is_full(sk))
 557                 goto exit_overflow;
 558
 559         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 560                 goto exit;
 561
 562         newsk = dccp_create_openreq_child(sk, req, skb);
 563         if (newsk == NULL)
 564                 goto exit;
 565
 566         sk_setup_caps(newsk, dst);
 567
 568         newdp              = dccp_sk(newsk);
 569         newinet            = inet_sk(newsk);
 570         ireq               = inet_rsk(req);
 571         newinet->daddr     = ireq->rmt_addr;
 572         newinet->rcv_saddr = ireq->loc_addr;
 573         newinet->saddr     = ireq->loc_addr;
 574         newinet->opt       = ireq->opt;
 575         ireq->opt          = NULL;
 576         newinet->mc_index  = inet_iif(skb);
 577         newinet->mc_ttl    = skb->nh.iph->ttl;
 578         newinet->id        = jiffies;
 579
 580         dccp_sync_mss(newsk, dst_mtu(dst));
 581
 582         __inet_hash(&dccp_hashinfo, newsk, 0);
 583         __inet_inherit_port(&dccp_hashinfo, sk, newsk);
 584
 585         return newsk;
 586
 587 exit_overflow:
 588         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
 589 exit:
 590         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
 591         dst_release(dst);
 592         return NULL;
 593 }
 594
 595 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 596
 597 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 598 {
 599         const struct dccp_hdr *dh = dccp_hdr(skb);
 600         const struct iphdr *iph = skb->nh.iph;
 601         struct sock *nsk;
 602         struct request_sock **prev;
 603         /* Find possible connection requests. */
 604         struct request_sock *req = inet_csk_search_req(sk, &prev,
 605                                                        dh->dccph_sport,
 606                                                        iph->saddr, iph->daddr);
 607         if (req != NULL)
 608                 return dccp_check_req(sk, skb, req, prev);
 609
 610         nsk = inet_lookup_established(&dccp_hashinfo,
 611                                       iph->saddr, dh->dccph_sport,
 612                                       iph->daddr, dh->dccph_dport,
 613                                       inet_iif(skb));
 614         if (nsk != NULL) {
 615                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 616                         bh_lock_sock(nsk);
 617                         return nsk;
 618                 }
 619                 inet_twsk_put(inet_twsk(nsk));
 620                 return NULL;
 621         }
 622
 623         return sk;
 624 }
 625
 626 int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
 627                      const __be32 daddr)
 628 {
 629         const struct dccp_hdr* dh = dccp_hdr(skb);
 630         int checksum_len;
 631         u32 tmp;
 632
 633         if (dh->dccph_cscov == 0)
 634                 checksum_len = skb->len;
 635         else {
 636                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 637                 checksum_len = checksum_len < skb->len ? checksum_len :
 638                                                          skb->len;
 639         }
 640
 641         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 642         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 643                                  IPPROTO_DCCP, tmp);
 644 }
 645
 646 EXPORT_SYMBOL_GPL(dccp_v4_checksum);
 647
 648 static int dccp_v4_verify_checksum(struct sk_buff *skb,
 649                                    const __be32 saddr, const __be32 daddr)
 650 {
 651         struct dccp_hdr *dh = dccp_hdr(skb);
 652         int checksum_len;
 653         u32 tmp;
 654
 655         if (dh->dccph_cscov == 0)
 656                 checksum_len = skb->len;
 657         else {
 658                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 659                 checksum_len = checksum_len < skb->len ? checksum_len :
 660                                                          skb->len;
 661         }
 662         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 663         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 664                                  IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
 665 }
 666
 667 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
 668                                            struct sk_buff *skb)
 669 {
 670         struct rtable *rt;
 671         struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
 672                             .nl_u = { .ip4_u =
 673                                       { .daddr = skb->nh.iph->saddr,
 674                                         .saddr = skb->nh.iph->daddr,
 675                                         .tos = RT_CONN_FLAGS(sk) } },
 676                             .proto = sk->sk_protocol,
 677                             .uli_u = { .ports =
 678                                        { .sport = dccp_hdr(skb)->dccph_dport,
 679                                          .dport = dccp_hdr(skb)->dccph_sport }
 680                                      }
 681                           };
 682
 683         security_skb_classify_flow(skb, &fl);
 684         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 685                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 686                 return NULL;
 687         }
 688
 689         return &rt->u.dst;
 690 }
 691
 692 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
 693 {
 694         int err;
 695         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 696         const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
 697                                        sizeof(struct dccp_hdr_ext) +
 698                                        sizeof(struct dccp_hdr_reset);
 699         struct sk_buff *skb;
 700         struct dst_entry *dst;
 701         u64 seqno;
 702
 703         /* Never send a reset in response to a reset. */
 704         if (rxdh->dccph_type == DCCP_PKT_RESET)
 705                 return;
 706
 707         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 708                 return;
 709
 710         dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
 711         if (dst == NULL)
 712                 return;
 713
 714         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header,
 715                         GFP_ATOMIC);
 716         if (skb == NULL)
 717                 goto out;
 718
 719         /* Reserve space for headers. */
 720         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 721         skb->dst = dst_clone(dst);
 722
 723         skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
 724         dh = dccp_hdr(skb);
 725         memset(dh, 0, dccp_hdr_reset_len);
 726
 727         /* Build DCCP header and checksum it. */
 728         dh->dccph_type     = DCCP_PKT_RESET;
 729         dh->dccph_sport    = rxdh->dccph_dport;
 730         dh->dccph_dport    = rxdh->dccph_sport;
 731         dh->dccph_doff     = dccp_hdr_reset_len / 4;
 732         dh->dccph_x        = 1;
 733         dccp_hdr_reset(skb)->dccph_reset_code =
 734                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 735
 736         /* See "8.3.1. Abnormal Termination" in RFC 4340 */
 737         seqno = 0;
 738         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 739                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 740
 741         dccp_hdr_set_seq(dh, seqno);
 742         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 743                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 744
 745         dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
 746                                               rxskb->nh.iph->daddr);
 747
 748         bh_lock_sock(dccp_v4_ctl_socket->sk);
 749         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 750                                     rxskb->nh.iph->daddr,
 751                                     rxskb->nh.iph->saddr, NULL);
 752         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 753
 754         if (err == NET_XMIT_CN || err == 0) {
 755                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 756                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 757         }
 758 out:
 759          dst_release(dst);
 760 }
 761
 762 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 763 {
 764         struct dccp_hdr *dh = dccp_hdr(skb);
 765
 766         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 767                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 768                         goto reset;
 769                 return 0;
 770         }
 771
 772         /*
 773          *  Step 3: Process LISTEN state
 774          *     If S.state == LISTEN,
 775          *        If P.type == Request or P contains a valid Init Cookie
 776          *              option,
 777          *           * Must scan the packet's options to check for an Init
 778          *              Cookie.  Only the Init Cookie is processed here,
 779          *              however; other options are processed in Step 8.  This
 780          *              scan need only be performed if the endpoint uses Init
 781          *              Cookies *
 782          *           * Generate a new socket and switch to that socket *
 783          *           Set S := new socket for this port pair
 784          *           S.state = RESPOND
 785          *           Choose S.ISS (initial seqno) or set from Init Cookie
 786          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 787          *           Continue with S.state == RESPOND
 788          *           * A Response packet will be generated in Step 11 *
 789          *        Otherwise,
 790          *           Generate Reset(No Connection) unless P.type == Reset
 791          *           Drop packet and return
 792          *
 793          * NOTE: the check for the packet types is done in
 794          *       dccp_rcv_state_process
 795          */
 796         if (sk->sk_state == DCCP_LISTEN) {
 797                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 798
 799                 if (nsk == NULL)
 800                         goto discard;
 801
 802                 if (nsk != sk) {
 803                         if (dccp_child_process(sk, nsk, skb))
 804                                 goto reset;
 805                         return 0;
 806                 }
 807         }
 808
 809         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 810                 goto reset;
 811         return 0;
 812
 813 reset:
 814         dccp_v4_ctl_send_reset(skb);
 815 discard:
 816         kfree_skb(skb);
 817         return 0;
 818 }
 819
 820 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 821
 822 int dccp_invalid_packet(struct sk_buff *skb)
 823 {
 824         const struct dccp_hdr *dh;
 825
 826         if (skb->pkt_type != PACKET_HOST)
 827                 return 1;
 828
 829         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 830                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
 831                 return 1;
 832         }
 833
 834         dh = dccp_hdr(skb);
 835
 836         /* If the packet type is not understood, drop packet and return */
 837         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 838                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
 839                 return 1;
 840         }
 841
 842         /*
 843          * If P.Data Offset is too small for packet type, or too large for
 844          * packet, drop packet and return
 845          */
 846         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 847                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 848                                             "too small 1\n",
 849                                dh->dccph_doff);
 850                 return 1;
 851         }
 852
 853         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 854                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 855                                             "too small 2\n",
 856                                dh->dccph_doff);
 857                 return 1;
 858         }
 859
 860         dh = dccp_hdr(skb);
 861
 862         /*
 863          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 864          * has short sequence numbers), drop packet and return
 865          */
 866         if (dh->dccph_x == 0 &&
 867             dh->dccph_type != DCCP_PKT_DATA &&
 868             dh->dccph_type != DCCP_PKT_ACK &&
 869             dh->dccph_type != DCCP_PKT_DATAACK) {
 870                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
 871                                             "nor DataAck and P.X == 0\n",
 872                                dccp_packet_name(dh->dccph_type));
 873                 return 1;
 874         }
 875
 876         return 0;
 877 }
 878
 879 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 880
 881 /* this is called when real data arrives */
 882 static int dccp_v4_rcv(struct sk_buff *skb)
 883 {
 884         const struct dccp_hdr *dh;
 885         struct sock *sk;
 886
 887         /* Step 1: Check header basics: */
 888
 889         if (dccp_invalid_packet(skb))
 890                 goto discard_it;
 891
 892         /* If the header checksum is incorrect, drop packet and return */
 893         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
 894                                     skb->nh.iph->daddr) < 0) {
 895                 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
 896                                __FUNCTION__);
 897                 goto discard_it;
 898         }
 899
 900         dh = dccp_hdr(skb);
 901
 902         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
 903         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 904
 905         dccp_pr_debug("%8.8s "
 906                       "src=%u.%u.%u.%u@%-5d "
 907                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 908                       dccp_packet_name(dh->dccph_type),
 909                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
 910                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
 911                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 912
 913         if (dccp_packet_without_ack(skb)) {
 914                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 915                 dccp_pr_debug_cat("\n");
 916         } else {
 917                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 918                 dccp_pr_debug_cat(", ack=%llu\n",
 919                                   (unsigned long long)
 920                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 921         }
 922
 923         /* Step 2:
 924          *      Look up flow ID in table and get corresponding socket */
 925         sk = __inet_lookup(&dccp_hashinfo,
 926                            skb->nh.iph->saddr, dh->dccph_sport,
 927                            skb->nh.iph->daddr, dh->dccph_dport,
 928                            inet_iif(skb));
 929
 930         /*
 931          * Step 2:
 932          *      If no socket ...
 933          *              Generate Reset(No Connection) unless P.type == Reset
 934          *              Drop packet and return
 935          */
 936         if (sk == NULL) {
 937                 dccp_pr_debug("failed to look up flow ID in table and "
 938                               "get corresponding socket\n");
 939                 goto no_dccp_socket;
 940         }
 941
 942         /*
 943          * Step 2:
 944          *      ... or S.state == TIMEWAIT,
 945          *              Generate Reset(No Connection) unless P.type == Reset
 946          *              Drop packet and return
 947          */
 948
 949         if (sk->sk_state == DCCP_TIME_WAIT) {
 950                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
 951                               "do_time_wait\n");
 952                 goto do_time_wait;
 953         }
 954
 955         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 956                 goto discard_and_relse;
 957         nf_reset(skb);
 958
 959         return sk_receive_skb(sk, skb);
 960
 961 no_dccp_socket:
 962         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 963                 goto discard_it;
 964         /*
 965          * Step 2:
 966          *              Generate Reset(No Connection) unless P.type == Reset
 967          *              Drop packet and return
 968          */
 969         if (dh->dccph_type != DCCP_PKT_RESET) {
 970                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 971                                         DCCP_RESET_CODE_NO_CONNECTION;
 972                 dccp_v4_ctl_send_reset(skb);
 973         }
 974
 975 discard_it:
 976         /* Discard frame. */
 977         kfree_skb(skb);
 978         return 0;
 979
 980 discard_and_relse:
 981         sock_put(sk);
 982         goto discard_it;
 983
 984 do_time_wait:
 985         inet_twsk_put(inet_twsk(sk));
 986         goto no_dccp_socket;
 987 }
 988
 989 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 990         .queue_xmit        = ip_queue_xmit,
 991         .send_check        = dccp_v4_send_check,
 992         .rebuild_header    = inet_sk_rebuild_header,
 993         .conn_request      = dccp_v4_conn_request,
 994         .syn_recv_sock     = dccp_v4_request_recv_sock,
 995         .net_header_len    = sizeof(struct iphdr),
 996         .setsockopt        = ip_setsockopt,
 997         .getsockopt        = ip_getsockopt,
 998         .addr2sockaddr     = inet_csk_addr2sockaddr,
 999         .sockaddr_len      = sizeof(struct sockaddr_in),
1000 #ifdef CONFIG_COMPAT
1001         .compat_setsockopt = compat_ip_setsockopt,
1002         .compat_getsockopt = compat_ip_getsockopt,
1003 #endif
1004 };
1005
1006 static int dccp_v4_init_sock(struct sock *sk)
1007 {
1008         static __u8 dccp_v4_ctl_sock_initialized;
1009         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
1010
1011         if (err == 0) {
1012                 if (unlikely(!dccp_v4_ctl_sock_initialized))
1013                         dccp_v4_ctl_sock_initialized = 1;
1014                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
1015         }
1016
1017         return err;
1018 }
1019
1020 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1021 {
1022         kfree(inet_rsk(req)->opt);
1023 }
1024
1025 static struct request_sock_ops dccp_request_sock_ops = {
1026         .family         = PF_INET,
1027         .obj_size       = sizeof(struct dccp_request_sock),
1028         .rtx_syn_ack    = dccp_v4_send_response,
1029         .send_ack       = dccp_v4_reqsk_send_ack,
1030         .destructor     = dccp_v4_reqsk_destructor,
1031         .send_reset     = dccp_v4_ctl_send_reset,
1032 };
1033
1034 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1035         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
1036 };
1037
1038 static struct proto dccp_v4_prot = {
1039         .name                   = "DCCP",
1040         .owner                  = THIS_MODULE,
1041         .close                  = dccp_close,
1042         .connect                = dccp_v4_connect,
1043         .disconnect             = dccp_disconnect,
1044         .ioctl                  = dccp_ioctl,
1045         .init                   = dccp_v4_init_sock,
1046         .setsockopt             = dccp_setsockopt,
1047         .getsockopt             = dccp_getsockopt,
1048         .sendmsg                = dccp_sendmsg,
1049         .recvmsg                = dccp_recvmsg,
1050         .backlog_rcv            = dccp_v4_do_rcv,
1051         .hash                   = dccp_hash,
1052         .unhash                 = dccp_unhash,
1053         .accept                 = inet_csk_accept,
1054         .get_port               = dccp_v4_get_port,
1055         .shutdown               = dccp_shutdown,
1056         .destroy                = dccp_destroy_sock,
1057         .orphan_count           = &dccp_orphan_count,
1058         .max_header             = MAX_DCCP_HEADER,
1059         .obj_size               = sizeof(struct dccp_sock),
1060         .rsk_prot               = &dccp_request_sock_ops,
1061         .twsk_prot              = &dccp_timewait_sock_ops,
1062 #ifdef CONFIG_COMPAT
1063         .compat_setsockopt      = compat_dccp_setsockopt,
1064         .compat_getsockopt      = compat_dccp_getsockopt,
1065 #endif
1066 };
1067
1068 static struct net_protocol dccp_v4_protocol = {
1069         .handler        = dccp_v4_rcv,
1070         .err_handler    = dccp_v4_err,
1071         .no_policy      = 1,
1072 };
1073
1074 static const struct proto_ops inet_dccp_ops = {
1075         .family            = PF_INET,
1076         .owner             = THIS_MODULE,
1077         .release           = inet_release,
1078         .bind              = inet_bind,
1079         .connect           = inet_stream_connect,
1080         .socketpair        = sock_no_socketpair,
1081         .accept            = inet_accept,
1082         .getname           = inet_getname,
1083         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1084         .poll              = dccp_poll,
1085         .ioctl             = inet_ioctl,
1086         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1087         .listen            = inet_dccp_listen,
1088         .shutdown          = inet_shutdown,
1089         .setsockopt        = sock_common_setsockopt,
1090         .getsockopt        = sock_common_getsockopt,
1091         .sendmsg           = inet_sendmsg,
1092         .recvmsg           = sock_common_recvmsg,
1093         .mmap              = sock_no_mmap,
1094         .sendpage          = sock_no_sendpage,
1095 #ifdef CONFIG_COMPAT
1096         .compat_setsockopt = compat_sock_common_setsockopt,
1097         .compat_getsockopt = compat_sock_common_getsockopt,
1098 #endif
1099 };
1100
1101 static struct inet_protosw dccp_v4_protosw = {
1102         .type           = SOCK_DCCP,
1103         .protocol       = IPPROTO_DCCP,
1104         .prot           = &dccp_v4_prot,
1105         .ops            = &inet_dccp_ops,
1106         .capability     = -1,
1107         .no_check       = 0,
1108         .flags          = INET_PROTOSW_ICSK,
1109 };
1110
1111 static int __init dccp_v4_init(void)
1112 {
1113         int err = proto_register(&dccp_v4_prot, 1);
1114
1115         if (err != 0)
1116                 goto out;
1117
1118         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1119         if (err != 0)
1120                 goto out_proto_unregister;
1121
1122         inet_register_protosw(&dccp_v4_protosw);
1123
1124         err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1125                                        SOCK_DCCP, IPPROTO_DCCP);
1126         if (err)
1127                 goto out_unregister_protosw;
1128 out:
1129         return err;
1130 out_unregister_protosw:
1131         inet_unregister_protosw(&dccp_v4_protosw);
1132         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1133 out_proto_unregister:
1134         proto_unregister(&dccp_v4_prot);
1135         goto out;
1136 }
1137
1138 static void __exit dccp_v4_exit(void)
1139 {
1140         inet_unregister_protosw(&dccp_v4_protosw);
1141         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1142         proto_unregister(&dccp_v4_prot);
1143 }
1144
1145 module_init(dccp_v4_init);
1146 module_exit(dccp_v4_exit);
1147
1148 /*
1149  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1150  * values directly, Also cover the case where the protocol is not specified,
1151  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1152  */
1153 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
1154 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
1155 MODULE_LICENSE("GPL");
1156 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1157 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");