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/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/icmp.h>
  16 #include <linux/module.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/random.h>
  19
  20 #include <net/icmp.h>
  21 #include <net/inet_common.h>
  22 #include <net/inet_hashtables.h>
  23 #include <net/inet_sock.h>
  24 #include <net/protocol.h>
  25 #include <net/sock.h>
  26 #include <net/timewait_sock.h>
  27 #include <net/tcp_states.h>
  28 #include <net/xfrm.h>
  29
  30 #include "ackvec.h"
  31 #include "ccid.h"
  32 #include "dccp.h"
  33 #include "feat.h"
  34
  35 /*
  36  * This is the global socket data structure used for responding to
  37  * the Out-of-the-blue (OOTB) packets. A control sock will be created
  38  * for this socket at the initialization time.
  39  */
  40 static struct socket *dccp_v4_ctl_socket;
  41
  42 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
  43 {
  44         return inet_csk_get_port(&dccp_hashinfo, sk, snum,
  45                                  inet_csk_bind_conflict);
  46 }
  47
  48 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  49 {
  50         struct inet_sock *inet = inet_sk(sk);
  51         struct dccp_sock *dp = dccp_sk(sk);
  52         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  53         struct rtable *rt;
  54         u32 daddr, nexthop;
  55         int tmp;
  56         int err;
  57
  58         dp->dccps_role = DCCP_ROLE_CLIENT;
  59
  60         if (dccp_service_not_initialized(sk))
  61                 return -EPROTO;
  62
  63         if (addr_len < sizeof(struct sockaddr_in))
  64                 return -EINVAL;
  65
  66         if (usin->sin_family != AF_INET)
  67                 return -EAFNOSUPPORT;
  68
  69         nexthop = daddr = usin->sin_addr.s_addr;
  70         if (inet->opt != NULL && inet->opt->srr) {
  71                 if (daddr == 0)
  72                         return -EINVAL;
  73                 nexthop = inet->opt->faddr;
  74         }
  75
  76         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
  77                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  78                                IPPROTO_DCCP,
  79                                inet->sport, usin->sin_port, sk);
  80         if (tmp < 0)
  81                 return tmp;
  82
  83         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  84                 ip_rt_put(rt);
  85                 return -ENETUNREACH;
  86         }
  87
  88         if (inet->opt == NULL || !inet->opt->srr)
  89                 daddr = rt->rt_dst;
  90
  91         if (inet->saddr == 0)
  92                 inet->saddr = rt->rt_src;
  93         inet->rcv_saddr = inet->saddr;
  94
  95         inet->dport = usin->sin_port;
  96         inet->daddr = daddr;
  97
  98         inet_csk(sk)->icsk_ext_hdr_len = 0;
  99         if (inet->opt != NULL)
 100                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
 101         /*
 102          * Socket identity is still unknown (sport may be zero).
 103          * However we set state to DCCP_REQUESTING and not releasing socket
 104          * lock select source port, enter ourselves into the hash tables and
 105          * complete initialization after this.
 106          */
 107         dccp_set_state(sk, DCCP_REQUESTING);
 108         err = inet_hash_connect(&dccp_death_row, sk);
 109         if (err != 0)
 110                 goto failure;
 111
 112         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
 113                                 sk);
 114         if (err != 0)
 115                 goto failure;
 116
 117         /* OK, now commit destination to socket.  */
 118         sk_setup_caps(sk, &rt->u.dst);
 119
 120         dp->dccps_gar =
 121                 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
 122                                                             inet->daddr,
 123                                                             inet->sport,
 124                                                             usin->sin_port);
 125         dccp_update_gss(sk, dp->dccps_iss);
 126
 127         inet->id = dp->dccps_iss ^ jiffies;
 128
 129         err = dccp_connect(sk);
 130         rt = NULL;
 131         if (err != 0)
 132                 goto failure;
 133 out:
 134         return err;
 135 failure:
 136         /*
 137          * This unhashes the socket and releases the local port, if necessary.
 138          */
 139         dccp_set_state(sk, DCCP_CLOSED);
 140         ip_rt_put(rt);
 141         sk->sk_route_caps = 0;
 142         inet->dport = 0;
 143         goto out;
 144 }
 145
 146 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 147
 148 /*
 149  * This routine does path mtu discovery as defined in RFC1191.
 150  */
 151 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 152                                           const struct iphdr *iph,
 153                                           u32 mtu)
 154 {
 155         struct dst_entry *dst;
 156         const struct inet_sock *inet = inet_sk(sk);
 157         const struct dccp_sock *dp = dccp_sk(sk);
 158
 159         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 160          * send out by Linux are always < 576bytes so they should go through
 161          * unfragmented).
 162          */
 163         if (sk->sk_state == DCCP_LISTEN)
 164                 return;
 165
 166         /* We don't check in the destentry if pmtu discovery is forbidden
 167          * on this route. We just assume that no packet_to_big packets
 168          * are send back when pmtu discovery is not active.
 169          * There is a small race when the user changes this flag in the
 170          * route, but I think that's acceptable.
 171          */
 172         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 173                 return;
 174
 175         dst->ops->update_pmtu(dst, mtu);
 176
 177         /* Something is about to be wrong... Remember soft error
 178          * for the case, if this connection will not able to recover.
 179          */
 180         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 181                 sk->sk_err_soft = EMSGSIZE;
 182
 183         mtu = dst_mtu(dst);
 184
 185         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 186             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 187                 dccp_sync_mss(sk, mtu);
 188
 189                 /*
 190                  * From: draft-ietf-dccp-spec-11.txt
 191                  *
 192                  *      DCCP-Sync packets are the best choice for upward
 193                  *      probing, since DCCP-Sync probes do not risk application
 194                  *      data loss.
 195                  */
 196                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 197         } /* else let the usual retransmit timer handle it */
 198 }
 199
 200 static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
 201                                    struct request_sock *req)
 202 {
 203         int err;
 204         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 205         const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
 206                                      sizeof(struct dccp_hdr_ext) +
 207                                      sizeof(struct dccp_hdr_ack_bits);
 208         struct sk_buff *skb;
 209
 210         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 211                 return;
 212
 213         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
 214         if (skb == NULL)
 215                 return;
 216
 217         /* Reserve space for headers. */
 218         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 219
 220         skb->dst = dst_clone(rxskb->dst);
 221
 222         skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
 223         dh = dccp_hdr(skb);
 224         memset(dh, 0, dccp_hdr_ack_len);
 225
 226         /* Build DCCP header and checksum it. */
 227         dh->dccph_type     = DCCP_PKT_ACK;
 228         dh->dccph_sport    = rxdh->dccph_dport;
 229         dh->dccph_dport    = rxdh->dccph_sport;
 230         dh->dccph_doff     = dccp_hdr_ack_len / 4;
 231         dh->dccph_x        = 1;
 232
 233         dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
 234         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 235                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 236
 237         bh_lock_sock(dccp_v4_ctl_socket->sk);
 238         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 239                                     rxskb->nh.iph->daddr,
 240                                     rxskb->nh.iph->saddr, NULL);
 241         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 242
 243         if (err == NET_XMIT_CN || err == 0) {
 244                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 245                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 246         }
 247 }
 248
 249 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 250                                  struct dst_entry *dst)
 251 {
 252         int err = -1;
 253         struct sk_buff *skb;
 254
 255         /* First, grab a route. */
 256
 257         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 258                 goto out;
 259
 260         skb = dccp_make_response(sk, dst, req);
 261         if (skb != NULL) {
 262                 const struct inet_request_sock *ireq = inet_rsk(req);
 263                 struct dccp_hdr *dh = dccp_hdr(skb);
 264
 265                 dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
 266                                                       ireq->rmt_addr);
 267                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 268                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 269                                             ireq->rmt_addr,
 270                                             ireq->opt);
 271                 if (err == NET_XMIT_CN)
 272                         err = 0;
 273         }
 274
 275 out:
 276         dst_release(dst);
 277         return err;
 278 }
 279
 280 /*
 281  * This routine is called by the ICMP module when it gets some sort of error
 282  * condition. If err < 0 then the socket should be closed and the error
 283  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 284  * After adjustment header points to the first 8 bytes of the tcp header. We
 285  * need to find the appropriate port.
 286  *
 287  * The locking strategy used here is very "optimistic". When someone else
 288  * accesses the socket the ICMP is just dropped and for some paths there is no
 289  * check at all. A more general error queue to queue errors for later handling
 290  * is probably better.
 291  */
 292 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 293 {
 294         const struct iphdr *iph = (struct iphdr *)skb->data;
 295         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 296                                                         (iph->ihl << 2));
 297         struct dccp_sock *dp;
 298         struct inet_sock *inet;
 299         const int type = skb->h.icmph->type;
 300         const int code = skb->h.icmph->code;
 301         struct sock *sk;
 302         __u64 seq;
 303         int err;
 304
 305         if (skb->len < (iph->ihl << 2) + 8) {
 306                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 307                 return;
 308         }
 309
 310         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
 311                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 312         if (sk == NULL) {
 313                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 314                 return;
 315         }
 316
 317         if (sk->sk_state == DCCP_TIME_WAIT) {
 318                 inet_twsk_put((struct inet_timewait_sock *)sk);
 319                 return;
 320         }
 321
 322         bh_lock_sock(sk);
 323         /* If too many ICMPs get dropped on busy
 324          * servers this needs to be solved differently.
 325          */
 326         if (sock_owned_by_user(sk))
 327                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 328
 329         if (sk->sk_state == DCCP_CLOSED)
 330                 goto out;
 331
 332         dp = dccp_sk(sk);
 333         seq = dccp_hdr_seq(skb);
 334         if (sk->sk_state != DCCP_LISTEN &&
 335             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 336                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 337                 goto out;
 338         }
 339
 340         switch (type) {
 341         case ICMP_SOURCE_QUENCH:
 342                 /* Just silently ignore these. */
 343                 goto out;
 344         case ICMP_PARAMETERPROB:
 345                 err = EPROTO;
 346                 break;
 347         case ICMP_DEST_UNREACH:
 348                 if (code > NR_ICMP_UNREACH)
 349                         goto out;
 350
 351                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 352                         if (!sock_owned_by_user(sk))
 353                                 dccp_do_pmtu_discovery(sk, iph, info);
 354                         goto out;
 355                 }
 356
 357                 err = icmp_err_convert[code].errno;
 358                 break;
 359         case ICMP_TIME_EXCEEDED:
 360                 err = EHOSTUNREACH;
 361                 break;
 362         default:
 363                 goto out;
 364         }
 365
 366         switch (sk->sk_state) {
 367                 struct request_sock *req , **prev;
 368         case DCCP_LISTEN:
 369                 if (sock_owned_by_user(sk))
 370                         goto out;
 371                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 372                                           iph->daddr, iph->saddr);
 373                 if (!req)
 374                         goto out;
 375
 376                 /*
 377                  * ICMPs are not backlogged, hence we cannot get an established
 378                  * socket here.
 379                  */
 380                 BUG_TRAP(!req->sk);
 381
 382                 if (seq != dccp_rsk(req)->dreq_iss) {
 383                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 384                         goto out;
 385                 }
 386                 /*
 387                  * Still in RESPOND, just remove it silently.
 388                  * There is no good way to pass the error to the newly
 389                  * created socket, and POSIX does not want network
 390                  * errors returned from accept().
 391                  */
 392                 inet_csk_reqsk_queue_drop(sk, req, prev);
 393                 goto out;
 394
 395         case DCCP_REQUESTING:
 396         case DCCP_RESPOND:
 397                 if (!sock_owned_by_user(sk)) {
 398                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 399                         sk->sk_err = err;
 400
 401                         sk->sk_error_report(sk);
 402
 403                         dccp_done(sk);
 404                 } else
 405                         sk->sk_err_soft = err;
 406                 goto out;
 407         }
 408
 409         /* If we've already connected we will keep trying
 410          * until we time out, or the user gives up.
 411          *
 412          * rfc1122 4.2.3.9 allows to consider as hard errors
 413          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 414          * but it is obsoleted by pmtu discovery).
 415          *
 416          * Note, that in modern internet, where routing is unreliable
 417          * and in each dark corner broken firewalls sit, sending random
 418          * errors ordered by their masters even this two messages finally lose
 419          * their original sense (even Linux sends invalid PORT_UNREACHs)
 420          *
 421          * Now we are in compliance with RFCs.
 422          *                                                      --ANK (980905)
 423          */
 424
 425         inet = inet_sk(sk);
 426         if (!sock_owned_by_user(sk) && inet->recverr) {
 427                 sk->sk_err = err;
 428                 sk->sk_error_report(sk);
 429         } else /* Only an error on timeout */
 430                 sk->sk_err_soft = err;
 431 out:
 432         bh_unlock_sock(sk);
 433         sock_put(sk);
 434 }
 435
 436 /* This routine computes an IPv4 DCCP checksum. */
 437 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
 438 {
 439         const struct inet_sock *inet = inet_sk(sk);
 440         struct dccp_hdr *dh = dccp_hdr(skb);
 441
 442         dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
 443 }
 444
 445 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 446
 447 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
 448                                         const struct sk_buff *skb)
 449 {
 450         return secure_dccp_sequence_number(skb->nh.iph->daddr,
 451                                            skb->nh.iph->saddr,
 452                                            dccp_hdr(skb)->dccph_dport,
 453                                            dccp_hdr(skb)->dccph_sport);
 454 }
 455
 456 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 457 {
 458         struct inet_request_sock *ireq;
 459         struct dccp_sock dp;
 460         struct request_sock *req;
 461         struct dccp_request_sock *dreq;
 462         const __be32 saddr = skb->nh.iph->saddr;
 463         const __be32 daddr = skb->nh.iph->daddr;
 464         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 465         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 466         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
 467
 468         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 469         if (((struct rtable *)skb->dst)->rt_flags &
 470             (RTCF_BROADCAST | RTCF_MULTICAST)) {
 471                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 472                 goto drop;
 473         }
 474
 475         if (dccp_bad_service_code(sk, service)) {
 476                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 477                 goto drop;
 478         }
 479         /*
 480          * TW buckets are converted to open requests without
 481          * limitations, they conserve resources and peer is
 482          * evidently real one.
 483          */
 484         if (inet_csk_reqsk_queue_is_full(sk))
 485                 goto drop;
 486
 487         /*
 488          * Accept backlog is full. If we have already queued enough
 489          * of warm entries in syn queue, drop request. It is better than
 490          * clogging syn queue with openreqs with exponentially increasing
 491          * timeout.
 492          */
 493         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 494                 goto drop;
 495
 496         req = reqsk_alloc(sk->sk_prot->rsk_prot);
 497         if (req == NULL)
 498                 goto drop;
 499
 500         if (dccp_parse_options(sk, skb))
 501                 goto drop_and_free;
 502
 503         dccp_openreq_init(req, &dp, skb);
 504
 505         ireq = inet_rsk(req);
 506         ireq->loc_addr = daddr;
 507         ireq->rmt_addr = saddr;
 508         req->rcv_wnd    = 100; /* Fake, option parsing will get the
 509                                   right value */
 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, ntohs(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((struct inet_timewait_sock *)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         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 684                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 685                 return NULL;
 686         }
 687
 688         return &rt->u.dst;
 689 }
 690
 691 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
 692 {
 693         int err;
 694         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 695         const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
 696                                        sizeof(struct dccp_hdr_ext) +
 697                                        sizeof(struct dccp_hdr_reset);
 698         struct sk_buff *skb;
 699         struct dst_entry *dst;
 700         u64 seqno;
 701
 702         /* Never send a reset in response to a reset. */
 703         if (rxdh->dccph_type == DCCP_PKT_RESET)
 704                 return;
 705
 706         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 707                 return;
 708
 709         dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
 710         if (dst == NULL)
 711                 return;
 712
 713         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header,
 714                         GFP_ATOMIC);
 715         if (skb == NULL)
 716                 goto out;
 717
 718         /* Reserve space for headers. */
 719         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 720         skb->dst = dst_clone(dst);
 721
 722         skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
 723         dh = dccp_hdr(skb);
 724         memset(dh, 0, dccp_hdr_reset_len);
 725
 726         /* Build DCCP header and checksum it. */
 727         dh->dccph_type     = DCCP_PKT_RESET;
 728         dh->dccph_sport    = rxdh->dccph_dport;
 729         dh->dccph_dport    = rxdh->dccph_sport;
 730         dh->dccph_doff     = dccp_hdr_reset_len / 4;
 731         dh->dccph_x        = 1;
 732         dccp_hdr_reset(skb)->dccph_reset_code =
 733                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 734
 735         /* See "8.3.1. Abnormal Termination" in draft-ietf-dccp-spec-11 */
 736         seqno = 0;
 737         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 738                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 739
 740         dccp_hdr_set_seq(dh, seqno);
 741         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 742                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 743
 744         dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
 745                                               rxskb->nh.iph->daddr);
 746
 747         bh_lock_sock(dccp_v4_ctl_socket->sk);
 748         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 749                                     rxskb->nh.iph->daddr,
 750                                     rxskb->nh.iph->saddr, NULL);
 751         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 752
 753         if (err == NET_XMIT_CN || err == 0) {
 754                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 755                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 756         }
 757 out:
 758          dst_release(dst);
 759 }
 760
 761 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 762 {
 763         struct dccp_hdr *dh = dccp_hdr(skb);
 764
 765         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 766                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 767                         goto reset;
 768                 return 0;
 769         }
 770
 771         /*
 772          *  Step 3: Process LISTEN state
 773          *     If S.state == LISTEN,
 774          *        If P.type == Request or P contains a valid Init Cookie
 775          *              option,
 776          *           * Must scan the packet's options to check for an Init
 777          *              Cookie.  Only the Init Cookie is processed here,
 778          *              however; other options are processed in Step 8.  This
 779          *              scan need only be performed if the endpoint uses Init
 780          *              Cookies *
 781          *           * Generate a new socket and switch to that socket *
 782          *           Set S := new socket for this port pair
 783          *           S.state = RESPOND
 784          *           Choose S.ISS (initial seqno) or set from Init Cookie
 785          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 786          *           Continue with S.state == RESPOND
 787          *           * A Response packet will be generated in Step 11 *
 788          *        Otherwise,
 789          *           Generate Reset(No Connection) unless P.type == Reset
 790          *           Drop packet and return
 791          *
 792          * NOTE: the check for the packet types is done in
 793          *       dccp_rcv_state_process
 794          */
 795         if (sk->sk_state == DCCP_LISTEN) {
 796                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 797
 798                 if (nsk == NULL)
 799                         goto discard;
 800
 801                 if (nsk != sk) {
 802                         if (dccp_child_process(sk, nsk, skb))
 803                                 goto reset;
 804                         return 0;
 805                 }
 806         }
 807
 808         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 809                 goto reset;
 810         return 0;
 811
 812 reset:
 813         dccp_v4_ctl_send_reset(skb);
 814 discard:
 815         kfree_skb(skb);
 816         return 0;
 817 }
 818
 819 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 820
 821 int dccp_invalid_packet(struct sk_buff *skb)
 822 {
 823         const struct dccp_hdr *dh;
 824
 825         if (skb->pkt_type != PACKET_HOST)
 826                 return 1;
 827
 828         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 829                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
 830                 return 1;
 831         }
 832
 833         dh = dccp_hdr(skb);
 834
 835         /* If the packet type is not understood, drop packet and return */
 836         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 837                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
 838                 return 1;
 839         }
 840
 841         /*
 842          * If P.Data Offset is too small for packet type, or too large for
 843          * packet, drop packet and return
 844          */
 845         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 846                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 847                                             "too small 1\n",
 848                                dh->dccph_doff);
 849                 return 1;
 850         }
 851
 852         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 853                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 854                                             "too small 2\n",
 855                                dh->dccph_doff);
 856                 return 1;
 857         }
 858
 859         dh = dccp_hdr(skb);
 860
 861         /*
 862          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 863          * has short sequence numbers), drop packet and return
 864          */
 865         if (dh->dccph_x == 0 &&
 866             dh->dccph_type != DCCP_PKT_DATA &&
 867             dh->dccph_type != DCCP_PKT_ACK &&
 868             dh->dccph_type != DCCP_PKT_DATAACK) {
 869                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
 870                                             "nor DataAck and P.X == 0\n",
 871                                dccp_packet_name(dh->dccph_type));
 872                 return 1;
 873         }
 874
 875         return 0;
 876 }
 877
 878 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 879
 880 /* this is called when real data arrives */
 881 static int dccp_v4_rcv(struct sk_buff *skb)
 882 {
 883         const struct dccp_hdr *dh;
 884         struct sock *sk;
 885
 886         /* Step 1: Check header basics: */
 887
 888         if (dccp_invalid_packet(skb))
 889                 goto discard_it;
 890
 891         /* If the header checksum is incorrect, drop packet and return */
 892         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
 893                                     skb->nh.iph->daddr) < 0) {
 894                 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
 895                                __FUNCTION__);
 896                 goto discard_it;
 897         }
 898
 899         dh = dccp_hdr(skb);
 900
 901         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
 902         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 903
 904         dccp_pr_debug("%8.8s "
 905                       "src=%u.%u.%u.%u@%-5d "
 906                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 907                       dccp_packet_name(dh->dccph_type),
 908                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
 909                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
 910                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 911
 912         if (dccp_packet_without_ack(skb)) {
 913                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 914                 dccp_pr_debug_cat("\n");
 915         } else {
 916                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 917                 dccp_pr_debug_cat(", ack=%llu\n",
 918                                   (unsigned long long)
 919                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 920         }
 921
 922         /* Step 2:
 923          *      Look up flow ID in table and get corresponding socket */
 924         sk = __inet_lookup(&dccp_hashinfo,
 925                            skb->nh.iph->saddr, dh->dccph_sport,
 926                            skb->nh.iph->daddr, ntohs(dh->dccph_dport),
 927                            inet_iif(skb));
 928
 929         /*
 930          * Step 2:
 931          *      If no socket ...
 932          *              Generate Reset(No Connection) unless P.type == Reset
 933          *              Drop packet and return
 934          */
 935         if (sk == NULL) {
 936                 dccp_pr_debug("failed to look up flow ID in table and "
 937                               "get corresponding socket\n");
 938                 goto no_dccp_socket;
 939         }
 940
 941         /*
 942          * Step 2:
 943          *      ... or S.state == TIMEWAIT,
 944          *              Generate Reset(No Connection) unless P.type == Reset
 945          *              Drop packet and return
 946          */
 947
 948         if (sk->sk_state == DCCP_TIME_WAIT) {
 949                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
 950                               "do_time_wait\n");
 951                 goto do_time_wait;
 952         }
 953
 954         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 955                 goto discard_and_relse;
 956         nf_reset(skb);
 957
 958         return sk_receive_skb(sk, skb);
 959
 960 no_dccp_socket:
 961         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 962                 goto discard_it;
 963         /*
 964          * Step 2:
 965          *              Generate Reset(No Connection) unless P.type == Reset
 966          *              Drop packet and return
 967          */
 968         if (dh->dccph_type != DCCP_PKT_RESET) {
 969                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 970                                         DCCP_RESET_CODE_NO_CONNECTION;
 971                 dccp_v4_ctl_send_reset(skb);
 972         }
 973
 974 discard_it:
 975         /* Discard frame. */
 976         kfree_skb(skb);
 977         return 0;
 978
 979 discard_and_relse:
 980         sock_put(sk);
 981         goto discard_it;
 982
 983 do_time_wait:
 984         inet_twsk_put((struct inet_timewait_sock *)sk);
 985         goto no_dccp_socket;
 986 }
 987
 988 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 989         .queue_xmit        = ip_queue_xmit,
 990         .send_check        = dccp_v4_send_check,
 991         .rebuild_header    = inet_sk_rebuild_header,
 992         .conn_request      = dccp_v4_conn_request,
 993         .syn_recv_sock     = dccp_v4_request_recv_sock,
 994         .net_header_len    = sizeof(struct iphdr),
 995         .setsockopt        = ip_setsockopt,
 996         .getsockopt        = ip_getsockopt,
 997         .addr2sockaddr     = inet_csk_addr2sockaddr,
 998         .sockaddr_len      = sizeof(struct sockaddr_in),
 999 #ifdef CONFIG_COMPAT
1000         .compat_setsockopt = compat_ip_setsockopt,
1001         .compat_getsockopt = compat_ip_getsockopt,
1002 #endif
1003 };
1004
1005 static int dccp_v4_init_sock(struct sock *sk)
1006 {
1007         static __u8 dccp_v4_ctl_sock_initialized;
1008         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
1009
1010         if (err == 0) {
1011                 if (unlikely(!dccp_v4_ctl_sock_initialized))
1012                         dccp_v4_ctl_sock_initialized = 1;
1013                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
1014         }
1015
1016         return err;
1017 }
1018
1019 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1020 {
1021         kfree(inet_rsk(req)->opt);
1022 }
1023
1024 static struct request_sock_ops dccp_request_sock_ops = {
1025         .family         = PF_INET,
1026         .obj_size       = sizeof(struct dccp_request_sock),
1027         .rtx_syn_ack    = dccp_v4_send_response,
1028         .send_ack       = dccp_v4_reqsk_send_ack,
1029         .destructor     = dccp_v4_reqsk_destructor,
1030         .send_reset     = dccp_v4_ctl_send_reset,
1031 };
1032
1033 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1034         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
1035 };
1036
1037 static struct proto dccp_v4_prot = {
1038         .name                   = "DCCP",
1039         .owner                  = THIS_MODULE,
1040         .close                  = dccp_close,
1041         .connect                = dccp_v4_connect,
1042         .disconnect             = dccp_disconnect,
1043         .ioctl                  = dccp_ioctl,
1044         .init                   = dccp_v4_init_sock,
1045         .setsockopt             = dccp_setsockopt,
1046         .getsockopt             = dccp_getsockopt,
1047         .sendmsg                = dccp_sendmsg,
1048         .recvmsg                = dccp_recvmsg,
1049         .backlog_rcv            = dccp_v4_do_rcv,
1050         .hash                   = dccp_hash,
1051         .unhash                 = dccp_unhash,
1052         .accept                 = inet_csk_accept,
1053         .get_port               = dccp_v4_get_port,
1054         .shutdown               = dccp_shutdown,
1055         .destroy                = dccp_destroy_sock,
1056         .orphan_count           = &dccp_orphan_count,
1057         .max_header             = MAX_DCCP_HEADER,
1058         .obj_size               = sizeof(struct dccp_sock),
1059         .rsk_prot               = &dccp_request_sock_ops,
1060         .twsk_prot              = &dccp_timewait_sock_ops,
1061 #ifdef CONFIG_COMPAT
1062         .compat_setsockopt      = compat_dccp_setsockopt,
1063         .compat_getsockopt      = compat_dccp_getsockopt,
1064 #endif
1065 };
1066
1067 static struct net_protocol dccp_v4_protocol = {
1068         .handler        = dccp_v4_rcv,
1069         .err_handler    = dccp_v4_err,
1070         .no_policy      = 1,
1071 };
1072
1073 static const struct proto_ops inet_dccp_ops = {
1074         .family            = PF_INET,
1075         .owner             = THIS_MODULE,
1076         .release           = inet_release,
1077         .bind              = inet_bind,
1078         .connect           = inet_stream_connect,
1079         .socketpair        = sock_no_socketpair,
1080         .accept            = inet_accept,
1081         .getname           = inet_getname,
1082         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1083         .poll              = dccp_poll,
1084         .ioctl             = inet_ioctl,
1085         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1086         .listen            = inet_dccp_listen,
1087         .shutdown          = inet_shutdown,
1088         .setsockopt        = sock_common_setsockopt,
1089         .getsockopt        = sock_common_getsockopt,
1090         .sendmsg           = inet_sendmsg,
1091         .recvmsg           = sock_common_recvmsg,
1092         .mmap              = sock_no_mmap,
1093         .sendpage          = sock_no_sendpage,
1094 #ifdef CONFIG_COMPAT
1095         .compat_setsockopt = compat_sock_common_setsockopt,
1096         .compat_getsockopt = compat_sock_common_getsockopt,
1097 #endif
1098 };
1099
1100 static struct inet_protosw dccp_v4_protosw = {
1101         .type           = SOCK_DCCP,
1102         .protocol       = IPPROTO_DCCP,
1103         .prot           = &dccp_v4_prot,
1104         .ops            = &inet_dccp_ops,
1105         .capability     = -1,
1106         .no_check       = 0,
1107         .flags          = INET_PROTOSW_ICSK,
1108 };
1109
1110 static int __init dccp_v4_init(void)
1111 {
1112         int err = proto_register(&dccp_v4_prot, 1);
1113
1114         if (err != 0)
1115                 goto out;
1116
1117         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1118         if (err != 0)
1119                 goto out_proto_unregister;
1120
1121         inet_register_protosw(&dccp_v4_protosw);
1122
1123         err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1124                                        SOCK_DCCP, IPPROTO_DCCP);
1125         if (err)
1126                 goto out_unregister_protosw;
1127 out:
1128         return err;
1129 out_unregister_protosw:
1130         inet_unregister_protosw(&dccp_v4_protosw);
1131         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1132 out_proto_unregister:
1133         proto_unregister(&dccp_v4_prot);
1134         goto out;
1135 }
1136
1137 static void __exit dccp_v4_exit(void)
1138 {
1139         inet_unregister_protosw(&dccp_v4_protosw);
1140         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1141         proto_unregister(&dccp_v4_prot);
1142 }
1143
1144 module_init(dccp_v4_init);
1145 module_exit(dccp_v4_exit);
1146
1147 /*
1148  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1149  * values directly, Also cover the case where the protocol is not specified,
1150  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1151  */
1152 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
1153 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
1154 MODULE_LICENSE("GPL");
1155 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1156 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");