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