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   1 /*
   2  *  net/dccp/ipv4.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/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_hashtables.h>
  22 #include <net/inet_sock.h>
  23 #include <net/sock.h>
  24 #include <net/timewait_sock.h>
  25 #include <net/tcp_states.h>
  26 #include <net/xfrm.h>
  27
  28 #include "ackvec.h"
  29 #include "ccid.h"
  30 #include "dccp.h"
  31
  32 struct inet_hashinfo __cacheline_aligned dccp_hashinfo = {
  33         .lhash_lock     = RW_LOCK_UNLOCKED,
  34         .lhash_users    = ATOMIC_INIT(0),
  35         .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait),
  36 };
  37
  38 EXPORT_SYMBOL_GPL(dccp_hashinfo);
  39
  40 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
  41 {
  42         return inet_csk_get_port(&dccp_hashinfo, sk, snum,
  43                                  inet_csk_bind_conflict);
  44 }
  45
  46 static void dccp_v4_hash(struct sock *sk)
  47 {
  48         inet_hash(&dccp_hashinfo, sk);
  49 }
  50
  51 void dccp_unhash(struct sock *sk)
  52 {
  53         inet_unhash(&dccp_hashinfo, sk);
  54 }
  55
  56 EXPORT_SYMBOL_GPL(dccp_unhash);
  57
  58 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  59 {
  60         struct inet_sock *inet = inet_sk(sk);
  61         struct dccp_sock *dp = dccp_sk(sk);
  62         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  63         struct rtable *rt;
  64         u32 daddr, nexthop;
  65         int tmp;
  66         int err;
  67
  68         dp->dccps_role = DCCP_ROLE_CLIENT;
  69
  70         if (dccp_service_not_initialized(sk))
  71                 return -EPROTO;
  72
  73         if (addr_len < sizeof(struct sockaddr_in))
  74                 return -EINVAL;
  75
  76         if (usin->sin_family != AF_INET)
  77                 return -EAFNOSUPPORT;
  78
  79         nexthop = daddr = usin->sin_addr.s_addr;
  80         if (inet->opt != NULL && inet->opt->srr) {
  81                 if (daddr == 0)
  82                         return -EINVAL;
  83                 nexthop = inet->opt->faddr;
  84         }
  85
  86         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
  87                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  88                                IPPROTO_DCCP,
  89                                inet->sport, usin->sin_port, sk);
  90         if (tmp < 0)
  91                 return tmp;
  92
  93         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  94                 ip_rt_put(rt);
  95                 return -ENETUNREACH;
  96         }
  97
  98         if (inet->opt == NULL || !inet->opt->srr)
  99                 daddr = rt->rt_dst;
 100
 101         if (inet->saddr == 0)
 102                 inet->saddr = rt->rt_src;
 103         inet->rcv_saddr = inet->saddr;
 104
 105         inet->dport = usin->sin_port;
 106         inet->daddr = daddr;
 107
 108         inet_csk(sk)->icsk_ext_hdr_len = 0;
 109         if (inet->opt != NULL)
 110                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
 111         /*
 112          * Socket identity is still unknown (sport may be zero).
 113          * However we set state to DCCP_REQUESTING and not releasing socket
 114          * lock select source port, enter ourselves into the hash tables and
 115          * complete initialization after this.
 116          */
 117         dccp_set_state(sk, DCCP_REQUESTING);
 118         err = inet_hash_connect(&dccp_death_row, sk);
 119         if (err != 0)
 120                 goto failure;
 121
 122         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
 123                                 sk);
 124         if (err != 0)
 125                 goto failure;
 126
 127         /* OK, now commit destination to socket.  */
 128         sk_setup_caps(sk, &rt->u.dst);
 129
 130         dp->dccps_gar =
 131                 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
 132                                                             inet->daddr,
 133                                                             inet->sport,
 134                                                             usin->sin_port);
 135         dccp_update_gss(sk, dp->dccps_iss);
 136
 137         inet->id = dp->dccps_iss ^ jiffies;
 138
 139         err = dccp_connect(sk);
 140         rt = NULL;
 141         if (err != 0)
 142                 goto failure;
 143 out:
 144         return err;
 145 failure:
 146         /*
 147          * This unhashes the socket and releases the local port, if necessary.
 148          */
 149         dccp_set_state(sk, DCCP_CLOSED);
 150         ip_rt_put(rt);
 151         sk->sk_route_caps = 0;
 152         inet->dport = 0;
 153         goto out;
 154 }
 155
 156 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 157
 158 /*
 159  * This routine does path mtu discovery as defined in RFC1191.
 160  */
 161 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 162                                           const struct iphdr *iph,
 163                                           u32 mtu)
 164 {
 165         struct dst_entry *dst;
 166         const struct inet_sock *inet = inet_sk(sk);
 167         const struct dccp_sock *dp = dccp_sk(sk);
 168
 169         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 170          * send out by Linux are always < 576bytes so they should go through
 171          * unfragmented).
 172          */
 173         if (sk->sk_state == DCCP_LISTEN)
 174                 return;
 175
 176         /* We don't check in the destentry if pmtu discovery is forbidden
 177          * on this route. We just assume that no packet_to_big packets
 178          * are send back when pmtu discovery is not active.
 179          * There is a small race when the user changes this flag in the
 180          * route, but I think that's acceptable.
 181          */
 182         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 183                 return;
 184
 185         dst->ops->update_pmtu(dst, mtu);
 186
 187         /* Something is about to be wrong... Remember soft error
 188          * for the case, if this connection will not able to recover.
 189          */
 190         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 191                 sk->sk_err_soft = EMSGSIZE;
 192
 193         mtu = dst_mtu(dst);
 194
 195         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 196             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 197                 dccp_sync_mss(sk, mtu);
 198
 199                 /*
 200                  * From: draft-ietf-dccp-spec-11.txt
 201                  *
 202                  *      DCCP-Sync packets are the best choice for upward
 203                  *      probing, since DCCP-Sync probes do not risk application
 204                  *      data loss.
 205                  */
 206                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 207         } /* else let the usual retransmit timer handle it */
 208 }
 209
 210 static void dccp_v4_ctl_send_ack(struct sk_buff *rxskb)
 211 {
 212         int err;
 213         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 214         const int dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
 215                                      sizeof(struct dccp_hdr_ext) +
 216                                      sizeof(struct dccp_hdr_ack_bits);
 217         struct sk_buff *skb;
 218
 219         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 220                 return;
 221
 222         skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
 223         if (skb == NULL)
 224                 return;
 225
 226         /* Reserve space for headers. */
 227         skb_reserve(skb, MAX_DCCP_HEADER);
 228
 229         skb->dst = dst_clone(rxskb->dst);
 230
 231         skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
 232         dh = dccp_hdr(skb);
 233         memset(dh, 0, dccp_hdr_ack_len);
 234
 235         /* Build DCCP header and checksum it. */
 236         dh->dccph_type     = DCCP_PKT_ACK;
 237         dh->dccph_sport    = rxdh->dccph_dport;
 238         dh->dccph_dport    = rxdh->dccph_sport;
 239         dh->dccph_doff     = dccp_hdr_ack_len / 4;
 240         dh->dccph_x        = 1;
 241
 242         dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
 243         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 244                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 245
 246         bh_lock_sock(dccp_ctl_socket->sk);
 247         err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
 248                                     rxskb->nh.iph->daddr,
 249                                     rxskb->nh.iph->saddr, NULL);
 250         bh_unlock_sock(dccp_ctl_socket->sk);
 251
 252         if (err == NET_XMIT_CN || err == 0) {
 253                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 254                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 255         }
 256 }
 257
 258 static void dccp_v4_reqsk_send_ack(struct sk_buff *skb,
 259                                    struct request_sock *req)
 260 {
 261         dccp_v4_ctl_send_ack(skb);
 262 }
 263
 264 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 265                                  struct dst_entry *dst)
 266 {
 267         int err = -1;
 268         struct sk_buff *skb;
 269
 270         /* First, grab a route. */
 271
 272         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 273                 goto out;
 274
 275         skb = dccp_make_response(sk, dst, req);
 276         if (skb != NULL) {
 277                 const struct inet_request_sock *ireq = inet_rsk(req);
 278
 279                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 280                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 281                                             ireq->rmt_addr,
 282                                             ireq->opt);
 283                 if (err == NET_XMIT_CN)
 284                         err = 0;
 285         }
 286
 287 out:
 288         dst_release(dst);
 289         return err;
 290 }
 291
 292 /*
 293  * This routine is called by the ICMP module when it gets some sort of error
 294  * condition. If err < 0 then the socket should be closed and the error
 295  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 296  * After adjustment header points to the first 8 bytes of the tcp header. We
 297  * need to find the appropriate port.
 298  *
 299  * The locking strategy used here is very "optimistic". When someone else
 300  * accesses the socket the ICMP is just dropped and for some paths there is no
 301  * check at all. A more general error queue to queue errors for later handling
 302  * is probably better.
 303  */
 304 void dccp_v4_err(struct sk_buff *skb, u32 info)
 305 {
 306         const struct iphdr *iph = (struct iphdr *)skb->data;
 307         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 308                                                         (iph->ihl << 2));
 309         struct dccp_sock *dp;
 310         struct inet_sock *inet;
 311         const int type = skb->h.icmph->type;
 312         const int code = skb->h.icmph->code;
 313         struct sock *sk;
 314         __u64 seq;
 315         int err;
 316
 317         if (skb->len < (iph->ihl << 2) + 8) {
 318                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 319                 return;
 320         }
 321
 322         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
 323                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 324         if (sk == NULL) {
 325                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 326                 return;
 327         }
 328
 329         if (sk->sk_state == DCCP_TIME_WAIT) {
 330                 inet_twsk_put((struct inet_timewait_sock *)sk);
 331                 return;
 332         }
 333
 334         bh_lock_sock(sk);
 335         /* If too many ICMPs get dropped on busy
 336          * servers this needs to be solved differently.
 337          */
 338         if (sock_owned_by_user(sk))
 339                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 340
 341         if (sk->sk_state == DCCP_CLOSED)
 342                 goto out;
 343
 344         dp = dccp_sk(sk);
 345         seq = dccp_hdr_seq(skb);
 346         if (sk->sk_state != DCCP_LISTEN &&
 347             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 348                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 349                 goto out;
 350         }
 351
 352         switch (type) {
 353         case ICMP_SOURCE_QUENCH:
 354                 /* Just silently ignore these. */
 355                 goto out;
 356         case ICMP_PARAMETERPROB:
 357                 err = EPROTO;
 358                 break;
 359         case ICMP_DEST_UNREACH:
 360                 if (code > NR_ICMP_UNREACH)
 361                         goto out;
 362
 363                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 364                         if (!sock_owned_by_user(sk))
 365                                 dccp_do_pmtu_discovery(sk, iph, info);
 366                         goto out;
 367                 }
 368
 369                 err = icmp_err_convert[code].errno;
 370                 break;
 371         case ICMP_TIME_EXCEEDED:
 372                 err = EHOSTUNREACH;
 373                 break;
 374         default:
 375                 goto out;
 376         }
 377
 378         switch (sk->sk_state) {
 379                 struct request_sock *req , **prev;
 380         case DCCP_LISTEN:
 381                 if (sock_owned_by_user(sk))
 382                         goto out;
 383                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 384                                           iph->daddr, iph->saddr);
 385                 if (!req)
 386                         goto out;
 387
 388                 /*
 389                  * ICMPs are not backlogged, hence we cannot get an established
 390                  * socket here.
 391                  */
 392                 BUG_TRAP(!req->sk);
 393
 394                 if (seq != dccp_rsk(req)->dreq_iss) {
 395                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 396                         goto out;
 397                 }
 398                 /*
 399                  * Still in RESPOND, just remove it silently.
 400                  * There is no good way to pass the error to the newly
 401                  * created socket, and POSIX does not want network
 402                  * errors returned from accept().
 403                  */
 404                 inet_csk_reqsk_queue_drop(sk, req, prev);
 405                 goto out;
 406
 407         case DCCP_REQUESTING:
 408         case DCCP_RESPOND:
 409                 if (!sock_owned_by_user(sk)) {
 410                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 411                         sk->sk_err = err;
 412
 413                         sk->sk_error_report(sk);
 414
 415                         dccp_done(sk);
 416                 } else
 417                         sk->sk_err_soft = err;
 418                 goto out;
 419         }
 420
 421         /* If we've already connected we will keep trying
 422          * until we time out, or the user gives up.
 423          *
 424          * rfc1122 4.2.3.9 allows to consider as hard errors
 425          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 426          * but it is obsoleted by pmtu discovery).
 427          *
 428          * Note, that in modern internet, where routing is unreliable
 429          * and in each dark corner broken firewalls sit, sending random
 430          * errors ordered by their masters even this two messages finally lose
 431          * their original sense (even Linux sends invalid PORT_UNREACHs)
 432          *
 433          * Now we are in compliance with RFCs.
 434          *                                                      --ANK (980905)
 435          */
 436
 437         inet = inet_sk(sk);
 438         if (!sock_owned_by_user(sk) && inet->recverr) {
 439                 sk->sk_err = err;
 440                 sk->sk_error_report(sk);
 441         } else /* Only an error on timeout */
 442                 sk->sk_err_soft = err;
 443 out:
 444         bh_unlock_sock(sk);
 445         sock_put(sk);
 446 }
 447
 448 /* This routine computes an IPv4 DCCP checksum. */
 449 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
 450 {
 451         const struct inet_sock *inet = inet_sk(sk);
 452         struct dccp_hdr *dh = dccp_hdr(skb);
 453
 454         dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
 455 }
 456
 457 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 458
 459 int dccp_v4_send_reset(struct sock *sk, enum dccp_reset_codes code)
 460 {
 461         struct sk_buff *skb;
 462         /*
 463          * FIXME: what if rebuild_header fails?
 464          * Should we be doing a rebuild_header here?
 465          */
 466         int err = inet_sk_rebuild_header(sk);
 467
 468         if (err != 0)
 469                 return err;
 470
 471         skb = dccp_make_reset(sk, sk->sk_dst_cache, code);
 472         if (skb != NULL) {
 473                 const struct inet_sock *inet = inet_sk(sk);
 474
 475                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 476                 err = ip_build_and_send_pkt(skb, sk,
 477                                             inet->saddr, inet->daddr, NULL);
 478                 if (err == NET_XMIT_CN)
 479                         err = 0;
 480         }
 481
 482         return err;
 483 }
 484
 485 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
 486                                         const struct sk_buff *skb)
 487 {
 488         return secure_dccp_sequence_number(skb->nh.iph->daddr,
 489                                            skb->nh.iph->saddr,
 490                                            dccp_hdr(skb)->dccph_dport,
 491                                            dccp_hdr(skb)->dccph_sport);
 492 }
 493
 494 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 495 {
 496         struct inet_request_sock *ireq;
 497         struct dccp_sock dp;
 498         struct request_sock *req;
 499         struct dccp_request_sock *dreq;
 500         const __u32 saddr = skb->nh.iph->saddr;
 501         const __u32 daddr = skb->nh.iph->daddr;
 502         const __u32 service = dccp_hdr_request(skb)->dccph_req_service;
 503         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 504         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
 505
 506         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 507         if (((struct rtable *)skb->dst)->rt_flags &
 508             (RTCF_BROADCAST | RTCF_MULTICAST)) {
 509                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 510                 goto drop;
 511         }
 512
 513         if (dccp_bad_service_code(sk, service)) {
 514                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 515                 goto drop;
 516         }
 517         /*
 518          * TW buckets are converted to open requests without
 519          * limitations, they conserve resources and peer is
 520          * evidently real one.
 521          */
 522         if (inet_csk_reqsk_queue_is_full(sk))
 523                 goto drop;
 524
 525         /*
 526          * Accept backlog is full. If we have already queued enough
 527          * of warm entries in syn queue, drop request. It is better than
 528          * clogging syn queue with openreqs with exponentially increasing
 529          * timeout.
 530          */
 531         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 532                 goto drop;
 533
 534         req = reqsk_alloc(sk->sk_prot->rsk_prot);
 535         if (req == NULL)
 536                 goto drop;
 537
 538         /* FIXME: process options */
 539
 540         dccp_openreq_init(req, &dp, skb);
 541
 542         ireq = inet_rsk(req);
 543         ireq->loc_addr = daddr;
 544         ireq->rmt_addr = saddr;
 545         req->rcv_wnd    = 100; /* Fake, option parsing will get the
 546                                   right value */
 547         ireq->opt       = NULL;
 548
 549         /*
 550          * Step 3: Process LISTEN state
 551          *
 552          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 553          *
 554          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 555          * dccp_create_openreq_child.
 556          */
 557         dreq = dccp_rsk(req);
 558         dreq->dreq_isr     = dcb->dccpd_seq;
 559         dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
 560         dreq->dreq_service = service;
 561
 562         if (dccp_v4_send_response(sk, req, NULL))
 563                 goto drop_and_free;
 564
 565         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 566         return 0;
 567
 568 drop_and_free:
 569         reqsk_free(req);
 570 drop:
 571         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 572         dcb->dccpd_reset_code = reset_code;
 573         return -1;
 574 }
 575
 576 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 577
 578 /*
 579  * The three way handshake has completed - we got a valid ACK or DATAACK -
 580  * now create the new socket.
 581  *
 582  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 583  */
 584 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 585                                        struct request_sock *req,
 586                                        struct dst_entry *dst)
 587 {
 588         struct inet_request_sock *ireq;
 589         struct inet_sock *newinet;
 590         struct dccp_sock *newdp;
 591         struct sock *newsk;
 592
 593         if (sk_acceptq_is_full(sk))
 594                 goto exit_overflow;
 595
 596         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 597                 goto exit;
 598
 599         newsk = dccp_create_openreq_child(sk, req, skb);
 600         if (newsk == NULL)
 601                 goto exit;
 602
 603         sk_setup_caps(newsk, dst);
 604
 605         newdp              = dccp_sk(newsk);
 606         newinet            = inet_sk(newsk);
 607         ireq               = inet_rsk(req);
 608         newinet->daddr     = ireq->rmt_addr;
 609         newinet->rcv_saddr = ireq->loc_addr;
 610         newinet->saddr     = ireq->loc_addr;
 611         newinet->opt       = ireq->opt;
 612         ireq->opt          = NULL;
 613         newinet->mc_index  = inet_iif(skb);
 614         newinet->mc_ttl    = skb->nh.iph->ttl;
 615         newinet->id        = jiffies;
 616
 617         dccp_sync_mss(newsk, dst_mtu(dst));
 618
 619         __inet_hash(&dccp_hashinfo, newsk, 0);
 620         __inet_inherit_port(&dccp_hashinfo, sk, newsk);
 621
 622         return newsk;
 623
 624 exit_overflow:
 625         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
 626 exit:
 627         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
 628         dst_release(dst);
 629         return NULL;
 630 }
 631
 632 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 633
 634 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 635 {
 636         const struct dccp_hdr *dh = dccp_hdr(skb);
 637         const struct iphdr *iph = skb->nh.iph;
 638         struct sock *nsk;
 639         struct request_sock **prev;
 640         /* Find possible connection requests. */
 641         struct request_sock *req = inet_csk_search_req(sk, &prev,
 642                                                        dh->dccph_sport,
 643                                                        iph->saddr, iph->daddr);
 644         if (req != NULL)
 645                 return dccp_check_req(sk, skb, req, prev);
 646
 647         nsk = __inet_lookup_established(&dccp_hashinfo,
 648                                         iph->saddr, dh->dccph_sport,
 649                                         iph->daddr, ntohs(dh->dccph_dport),
 650                                         inet_iif(skb));
 651         if (nsk != NULL) {
 652                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 653                         bh_lock_sock(nsk);
 654                         return nsk;
 655                 }
 656                 inet_twsk_put((struct inet_timewait_sock *)nsk);
 657                 return NULL;
 658         }
 659
 660         return sk;
 661 }
 662
 663 int dccp_v4_checksum(const struct sk_buff *skb, const u32 saddr,
 664                      const u32 daddr)
 665 {
 666         const struct dccp_hdr* dh = dccp_hdr(skb);
 667         int checksum_len;
 668         u32 tmp;
 669
 670         if (dh->dccph_cscov == 0)
 671                 checksum_len = skb->len;
 672         else {
 673                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 674                 checksum_len = checksum_len < skb->len ? checksum_len :
 675                                                          skb->len;
 676         }
 677
 678         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 679         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 680                                  IPPROTO_DCCP, tmp);
 681 }
 682
 683 static int dccp_v4_verify_checksum(struct sk_buff *skb,
 684                                    const u32 saddr, const u32 daddr)
 685 {
 686         struct dccp_hdr *dh = dccp_hdr(skb);
 687         int checksum_len;
 688         u32 tmp;
 689
 690         if (dh->dccph_cscov == 0)
 691                 checksum_len = skb->len;
 692         else {
 693                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 694                 checksum_len = checksum_len < skb->len ? checksum_len :
 695                                                          skb->len;
 696         }
 697         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 698         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 699                                  IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
 700 }
 701
 702 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
 703                                            struct sk_buff *skb)
 704 {
 705         struct rtable *rt;
 706         struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
 707                             .nl_u = { .ip4_u =
 708                                       { .daddr = skb->nh.iph->saddr,
 709                                         .saddr = skb->nh.iph->daddr,
 710                                         .tos = RT_CONN_FLAGS(sk) } },
 711                             .proto = sk->sk_protocol,
 712                             .uli_u = { .ports =
 713                                        { .sport = dccp_hdr(skb)->dccph_dport,
 714                                          .dport = dccp_hdr(skb)->dccph_sport }
 715                                      }
 716                           };
 717
 718         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 719                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 720                 return NULL;
 721         }
 722
 723         return &rt->u.dst;
 724 }
 725
 726 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
 727 {
 728         int err;
 729         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 730         const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
 731                                        sizeof(struct dccp_hdr_ext) +
 732                                        sizeof(struct dccp_hdr_reset);
 733         struct sk_buff *skb;
 734         struct dst_entry *dst;
 735         u64 seqno;
 736
 737         /* Never send a reset in response to a reset. */
 738         if (rxdh->dccph_type == DCCP_PKT_RESET)
 739                 return;
 740
 741         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 742                 return;
 743
 744         dst = dccp_v4_route_skb(dccp_ctl_socket->sk, rxskb);
 745         if (dst == NULL)
 746                 return;
 747
 748         skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
 749         if (skb == NULL)
 750                 goto out;
 751
 752         /* Reserve space for headers. */
 753         skb_reserve(skb, MAX_DCCP_HEADER);
 754         skb->dst = dst_clone(dst);
 755
 756         skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
 757         dh = dccp_hdr(skb);
 758         memset(dh, 0, dccp_hdr_reset_len);
 759
 760         /* Build DCCP header and checksum it. */
 761         dh->dccph_type     = DCCP_PKT_RESET;
 762         dh->dccph_sport    = rxdh->dccph_dport;
 763         dh->dccph_dport    = rxdh->dccph_sport;
 764         dh->dccph_doff     = dccp_hdr_reset_len / 4;
 765         dh->dccph_x        = 1;
 766         dccp_hdr_reset(skb)->dccph_reset_code =
 767                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 768
 769         /* See "8.3.1. Abnormal Termination" in draft-ietf-dccp-spec-11 */
 770         seqno = 0;
 771         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 772                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 773
 774         dccp_hdr_set_seq(dh, seqno);
 775         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 776                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 777
 778         dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
 779                                               rxskb->nh.iph->daddr);
 780
 781         bh_lock_sock(dccp_ctl_socket->sk);
 782         err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
 783                                     rxskb->nh.iph->daddr,
 784                                     rxskb->nh.iph->saddr, NULL);
 785         bh_unlock_sock(dccp_ctl_socket->sk);
 786
 787         if (err == NET_XMIT_CN || err == 0) {
 788                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 789                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 790         }
 791 out:
 792          dst_release(dst);
 793 }
 794
 795 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 796 {
 797         struct dccp_hdr *dh = dccp_hdr(skb);
 798
 799         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 800                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 801                         goto reset;
 802                 return 0;
 803         }
 804
 805         /*
 806          *  Step 3: Process LISTEN state
 807          *     If S.state == LISTEN,
 808          *        If P.type == Request or P contains a valid Init Cookie
 809          *              option,
 810          *           * Must scan the packet's options to check for an Init
 811          *              Cookie.  Only the Init Cookie is processed here,
 812          *              however; other options are processed in Step 8.  This
 813          *              scan need only be performed if the endpoint uses Init
 814          *              Cookies *
 815          *           * Generate a new socket and switch to that socket *
 816          *           Set S := new socket for this port pair
 817          *           S.state = RESPOND
 818          *           Choose S.ISS (initial seqno) or set from Init Cookie
 819          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 820          *           Continue with S.state == RESPOND
 821          *           * A Response packet will be generated in Step 11 *
 822          *        Otherwise,
 823          *           Generate Reset(No Connection) unless P.type == Reset
 824          *           Drop packet and return
 825          *
 826          * NOTE: the check for the packet types is done in
 827          *       dccp_rcv_state_process
 828          */
 829         if (sk->sk_state == DCCP_LISTEN) {
 830                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 831
 832                 if (nsk == NULL)
 833                         goto discard;
 834
 835                 if (nsk != sk) {
 836                         if (dccp_child_process(sk, nsk, skb))
 837                                 goto reset;
 838                         return 0;
 839                 }
 840         }
 841
 842         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 843                 goto reset;
 844         return 0;
 845
 846 reset:
 847         dccp_v4_ctl_send_reset(skb);
 848 discard:
 849         kfree_skb(skb);
 850         return 0;
 851 }
 852
 853 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 854
 855 int dccp_invalid_packet(struct sk_buff *skb)
 856 {
 857         const struct dccp_hdr *dh;
 858
 859         if (skb->pkt_type != PACKET_HOST)
 860                 return 1;
 861
 862         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 863                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
 864                 return 1;
 865         }
 866
 867         dh = dccp_hdr(skb);
 868
 869         /* If the packet type is not understood, drop packet and return */
 870         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 871                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
 872                 return 1;
 873         }
 874
 875         /*
 876          * If P.Data Offset is too small for packet type, or too large for
 877          * packet, drop packet and return
 878          */
 879         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 880                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 881                                             "too small 1\n",
 882                                dh->dccph_doff);
 883                 return 1;
 884         }
 885
 886         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 887                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 888                                             "too small 2\n",
 889                                dh->dccph_doff);
 890                 return 1;
 891         }
 892
 893         dh = dccp_hdr(skb);
 894
 895         /*
 896          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 897          * has short sequence numbers), drop packet and return
 898          */
 899         if (dh->dccph_x == 0 &&
 900             dh->dccph_type != DCCP_PKT_DATA &&
 901             dh->dccph_type != DCCP_PKT_ACK &&
 902             dh->dccph_type != DCCP_PKT_DATAACK) {
 903                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
 904                                             "nor DataAck and P.X == 0\n",
 905                                dccp_packet_name(dh->dccph_type));
 906                 return 1;
 907         }
 908
 909         return 0;
 910 }
 911
 912 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 913
 914 /* this is called when real data arrives */
 915 int dccp_v4_rcv(struct sk_buff *skb)
 916 {
 917         const struct dccp_hdr *dh;
 918         struct sock *sk;
 919
 920         /* Step 1: Check header basics: */
 921
 922         if (dccp_invalid_packet(skb))
 923                 goto discard_it;
 924
 925         /* If the header checksum is incorrect, drop packet and return */
 926         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
 927                                     skb->nh.iph->daddr) < 0) {
 928                 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
 929                                __FUNCTION__);
 930                 goto discard_it;
 931         }
 932
 933         dh = dccp_hdr(skb);
 934
 935         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
 936         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 937
 938         dccp_pr_debug("%8.8s "
 939                       "src=%u.%u.%u.%u@%-5d "
 940                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 941                       dccp_packet_name(dh->dccph_type),
 942                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
 943                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
 944                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 945
 946         if (dccp_packet_without_ack(skb)) {
 947                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 948                 dccp_pr_debug_cat("\n");
 949         } else {
 950                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 951                 dccp_pr_debug_cat(", ack=%llu\n",
 952                                   (unsigned long long)
 953                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 954         }
 955
 956         /* Step 2:
 957          *      Look up flow ID in table and get corresponding socket */
 958         sk = __inet_lookup(&dccp_hashinfo,
 959                            skb->nh.iph->saddr, dh->dccph_sport,
 960                            skb->nh.iph->daddr, ntohs(dh->dccph_dport),
 961                            inet_iif(skb));
 962
 963         /*
 964          * Step 2:
 965          *      If no socket ...
 966          *              Generate Reset(No Connection) unless P.type == Reset
 967          *              Drop packet and return
 968          */
 969         if (sk == NULL) {
 970                 dccp_pr_debug("failed to look up flow ID in table and "
 971                               "get corresponding socket\n");
 972                 goto no_dccp_socket;
 973         }
 974
 975         /*
 976          * Step 2:
 977          *      ... or S.state == TIMEWAIT,
 978          *              Generate Reset(No Connection) unless P.type == Reset
 979          *              Drop packet and return
 980          */
 981
 982         if (sk->sk_state == DCCP_TIME_WAIT) {
 983                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
 984                               "do_time_wait\n");
 985                 goto do_time_wait;
 986         }
 987
 988         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 989                 goto discard_and_relse;
 990         nf_reset(skb);
 991
 992         return sk_receive_skb(sk, skb);
 993
 994 no_dccp_socket:
 995         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 996                 goto discard_it;
 997         /*
 998          * Step 2:
 999          *              Generate Reset(No Connection) unless P.type == Reset
1000          *              Drop packet and return
1001          */
1002         if (dh->dccph_type != DCCP_PKT_RESET) {
1003                 DCCP_SKB_CB(skb)->dccpd_reset_code =
1004                                         DCCP_RESET_CODE_NO_CONNECTION;
1005                 dccp_v4_ctl_send_reset(skb);
1006         }
1007
1008 discard_it:
1009         /* Discard frame. */
1010         kfree_skb(skb);
1011         return 0;
1012
1013 discard_and_relse:
1014         sock_put(sk);
1015         goto discard_it;
1016
1017 do_time_wait:
1018         inet_twsk_put((struct inet_timewait_sock *)sk);
1019         goto no_dccp_socket;
1020 }
1021
1022 struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
1023         .queue_xmit     = ip_queue_xmit,
1024         .send_check     = dccp_v4_send_check,
1025         .rebuild_header = inet_sk_rebuild_header,
1026         .conn_request   = dccp_v4_conn_request,
1027         .syn_recv_sock  = dccp_v4_request_recv_sock,
1028         .net_header_len = sizeof(struct iphdr),
1029         .setsockopt     = ip_setsockopt,
1030         .getsockopt     = ip_getsockopt,
1031         .addr2sockaddr  = inet_csk_addr2sockaddr,
1032         .sockaddr_len   = sizeof(struct sockaddr_in),
1033 };
1034
1035 int dccp_v4_init_sock(struct sock *sk)
1036 {
1037         struct dccp_sock *dp = dccp_sk(sk);
1038         struct inet_connection_sock *icsk = inet_csk(sk);
1039         static int dccp_ctl_socket_init = 1;
1040
1041         dccp_options_init(&dp->dccps_options);
1042         do_gettimeofday(&dp->dccps_epoch);
1043
1044         /*
1045          * FIXME: We're hardcoding the CCID, and doing this at this point makes
1046          * the listening (master) sock get CCID control blocks, which is not
1047          * necessary, but for now, to not mess with the test userspace apps,
1048          * lets leave it here, later the real solution is to do this in a
1049          * setsockopt(CCIDs-I-want/accept). -acme
1050          */
1051         if (likely(!dccp_ctl_socket_init)) {
1052                 if (dp->dccps_options.dccpo_send_ack_vector) {
1053                         dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(GFP_KERNEL);
1054                         if (dp->dccps_hc_rx_ackvec == NULL)
1055                                 return -ENOMEM;
1056                 }
1057                 dp->dccps_hc_rx_ccid = ccid_init(dp->dccps_options.dccpo_rx_ccid,
1058                                                  sk);
1059                 dp->dccps_hc_tx_ccid = ccid_init(dp->dccps_options.dccpo_tx_ccid,
1060                                                  sk);
1061                 if (dp->dccps_hc_rx_ccid == NULL ||
1062                     dp->dccps_hc_tx_ccid == NULL) {
1063                         ccid_exit(dp->dccps_hc_rx_ccid, sk);
1064                         ccid_exit(dp->dccps_hc_tx_ccid, sk);
1065                         if (dp->dccps_options.dccpo_send_ack_vector) {
1066                                 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1067                                 dp->dccps_hc_rx_ackvec = NULL;
1068                         }
1069                         dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1070                         return -ENOMEM;
1071                 }
1072         } else
1073                 dccp_ctl_socket_init = 0;
1074
1075         dccp_init_xmit_timers(sk);
1076         icsk->icsk_rto = DCCP_TIMEOUT_INIT;
1077         sk->sk_state = DCCP_CLOSED;
1078         sk->sk_write_space = dccp_write_space;
1079         icsk->icsk_af_ops = &dccp_ipv4_af_ops;
1080         icsk->icsk_sync_mss = dccp_sync_mss;
1081         dp->dccps_mss_cache = 536;
1082         dp->dccps_role = DCCP_ROLE_UNDEFINED;
1083         dp->dccps_service = DCCP_SERVICE_INVALID_VALUE;
1084         dp->dccps_l_ack_ratio = dp->dccps_r_ack_ratio = 1;
1085
1086         return 0;
1087 }
1088
1089 EXPORT_SYMBOL_GPL(dccp_v4_init_sock);
1090
1091 int dccp_v4_destroy_sock(struct sock *sk)
1092 {
1093         struct dccp_sock *dp = dccp_sk(sk);
1094
1095         /*
1096          * DCCP doesn't use sk_write_queue, just sk_send_head
1097          * for retransmissions
1098          */
1099         if (sk->sk_send_head != NULL) {
1100                 kfree_skb(sk->sk_send_head);
1101                 sk->sk_send_head = NULL;
1102         }
1103
1104         /* Clean up a referenced DCCP bind bucket. */
1105         if (inet_csk(sk)->icsk_bind_hash != NULL)
1106                 inet_put_port(&dccp_hashinfo, sk);
1107
1108         kfree(dp->dccps_service_list);
1109         dp->dccps_service_list = NULL;
1110
1111         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
1112         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
1113         if (dp->dccps_options.dccpo_send_ack_vector) {
1114                 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1115                 dp->dccps_hc_rx_ackvec = NULL;
1116         }
1117         ccid_exit(dp->dccps_hc_rx_ccid, sk);
1118         ccid_exit(dp->dccps_hc_tx_ccid, sk);
1119         dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1120
1121         return 0;
1122 }
1123
1124 EXPORT_SYMBOL_GPL(dccp_v4_destroy_sock);
1125
1126 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1127 {
1128         kfree(inet_rsk(req)->opt);
1129 }
1130
1131 static struct request_sock_ops dccp_request_sock_ops = {
1132         .family         = PF_INET,
1133         .obj_size       = sizeof(struct dccp_request_sock),
1134         .rtx_syn_ack    = dccp_v4_send_response,
1135         .send_ack       = dccp_v4_reqsk_send_ack,
1136         .destructor     = dccp_v4_reqsk_destructor,
1137         .send_reset     = dccp_v4_ctl_send_reset,
1138 };
1139
1140 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1141         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
1142 };
1143
1144 struct proto dccp_prot = {
1145         .name                   = "DCCP",
1146         .owner                  = THIS_MODULE,
1147         .close                  = dccp_close,
1148         .connect                = dccp_v4_connect,
1149         .disconnect             = dccp_disconnect,
1150         .ioctl                  = dccp_ioctl,
1151         .init                   = dccp_v4_init_sock,
1152         .setsockopt             = dccp_setsockopt,
1153         .getsockopt             = dccp_getsockopt,
1154         .sendmsg                = dccp_sendmsg,
1155         .recvmsg                = dccp_recvmsg,
1156         .backlog_rcv            = dccp_v4_do_rcv,
1157         .hash                   = dccp_v4_hash,
1158         .unhash                 = dccp_unhash,
1159         .accept                 = inet_csk_accept,
1160         .get_port               = dccp_v4_get_port,
1161         .shutdown               = dccp_shutdown,
1162         .destroy                = dccp_v4_destroy_sock,
1163         .orphan_count           = &dccp_orphan_count,
1164         .max_header             = MAX_DCCP_HEADER,
1165         .obj_size               = sizeof(struct dccp_sock),
1166         .rsk_prot               = &dccp_request_sock_ops,
1167         .twsk_prot              = &dccp_timewait_sock_ops,
1168 };
1169
1170 EXPORT_SYMBOL_GPL(dccp_prot);