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         u32 daddr, nexthop;
  54         int tmp;
  55         int err;
  56
  57         dp->dccps_role = DCCP_ROLE_CLIENT;
  58
  59         if (dccp_service_not_initialized(sk))
  60                 return -EPROTO;
  61
  62         if (addr_len < sizeof(struct sockaddr_in))
  63                 return -EINVAL;
  64
  65         if (usin->sin_family != AF_INET)
  66                 return -EAFNOSUPPORT;
  67
  68         nexthop = daddr = usin->sin_addr.s_addr;
  69         if (inet->opt != NULL && inet->opt->srr) {
  70                 if (daddr == 0)
  71                         return -EINVAL;
  72                 nexthop = inet->opt->faddr;
  73         }
  74
  75         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
  76                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  77                                IPPROTO_DCCP,
  78                                inet->sport, usin->sin_port, sk);
  79         if (tmp < 0)
  80                 return tmp;
  81
  82         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  83                 ip_rt_put(rt);
  84                 return -ENETUNREACH;
  85         }
  86
  87         if (inet->opt == NULL || !inet->opt->srr)
  88                 daddr = rt->rt_dst;
  89
  90         if (inet->saddr == 0)
  91                 inet->saddr = rt->rt_src;
  92         inet->rcv_saddr = inet->saddr;
  93
  94         inet->dport = usin->sin_port;
  95         inet->daddr = daddr;
  96
  97         inet_csk(sk)->icsk_ext_hdr_len = 0;
  98         if (inet->opt != NULL)
  99                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
 100         /*
 101          * Socket identity is still unknown (sport may be zero).
 102          * However we set state to DCCP_REQUESTING and not releasing socket
 103          * lock select source port, enter ourselves into the hash tables and
 104          * complete initialization after this.
 105          */
 106         dccp_set_state(sk, DCCP_REQUESTING);
 107         err = inet_hash_connect(&dccp_death_row, sk);
 108         if (err != 0)
 109                 goto failure;
 110
 111         err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
 112                                 sk);
 113         if (err != 0)
 114                 goto failure;
 115
 116         /* OK, now commit destination to socket.  */
 117         sk_setup_caps(sk, &rt->u.dst);
 118
 119         dp->dccps_gar =
 120                 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
 121                                                             inet->daddr,
 122                                                             inet->sport,
 123                                                             usin->sin_port);
 124         dccp_update_gss(sk, dp->dccps_iss);
 125
 126         inet->id = dp->dccps_iss ^ jiffies;
 127
 128         err = dccp_connect(sk);
 129         rt = NULL;
 130         if (err != 0)
 131                 goto failure;
 132 out:
 133         return err;
 134 failure:
 135         /*
 136          * This unhashes the socket and releases the local port, if necessary.
 137          */
 138         dccp_set_state(sk, DCCP_CLOSED);
 139         ip_rt_put(rt);
 140         sk->sk_route_caps = 0;
 141         inet->dport = 0;
 142         goto out;
 143 }
 144
 145 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 146
 147 /*
 148  * This routine does path mtu discovery as defined in RFC1191.
 149  */
 150 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 151                                           const struct iphdr *iph,
 152                                           u32 mtu)
 153 {
 154         struct dst_entry *dst;
 155         const struct inet_sock *inet = inet_sk(sk);
 156         const struct dccp_sock *dp = dccp_sk(sk);
 157
 158         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 159          * send out by Linux are always < 576bytes so they should go through
 160          * unfragmented).
 161          */
 162         if (sk->sk_state == DCCP_LISTEN)
 163                 return;
 164
 165         /* We don't check in the destentry if pmtu discovery is forbidden
 166          * on this route. We just assume that no packet_to_big packets
 167          * are send back when pmtu discovery is not active.
 168          * There is a small race when the user changes this flag in the
 169          * route, but I think that's acceptable.
 170          */
 171         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 172                 return;
 173
 174         dst->ops->update_pmtu(dst, mtu);
 175
 176         /* Something is about to be wrong... Remember soft error
 177          * for the case, if this connection will not able to recover.
 178          */
 179         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 180                 sk->sk_err_soft = EMSGSIZE;
 181
 182         mtu = dst_mtu(dst);
 183
 184         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 185             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 186                 dccp_sync_mss(sk, mtu);
 187
 188                 /*
 189                  * From: draft-ietf-dccp-spec-11.txt
 190                  *
 191                  *      DCCP-Sync packets are the best choice for upward
 192                  *      probing, since DCCP-Sync probes do not risk application
 193                  *      data loss.
 194                  */
 195                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 196         } /* else let the usual retransmit timer handle it */
 197 }
 198
 199 static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
 200                                    struct request_sock *req)
 201 {
 202         int err;
 203         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
 204         const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
 205                                      sizeof(struct dccp_hdr_ext) +
 206                                      sizeof(struct dccp_hdr_ack_bits);
 207         struct sk_buff *skb;
 208
 209         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
 210                 return;
 211
 212         skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
 213         if (skb == NULL)
 214                 return;
 215
 216         /* Reserve space for headers. */
 217         skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
 218
 219         skb->dst = dst_clone(rxskb->dst);
 220
 221         skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
 222         dh = dccp_hdr(skb);
 223         memset(dh, 0, dccp_hdr_ack_len);
 224
 225         /* Build DCCP header and checksum it. */
 226         dh->dccph_type     = DCCP_PKT_ACK;
 227         dh->dccph_sport    = rxdh->dccph_dport;
 228         dh->dccph_dport    = rxdh->dccph_sport;
 229         dh->dccph_doff     = dccp_hdr_ack_len / 4;
 230         dh->dccph_x        = 1;
 231
 232         dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
 233         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 234                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 235
 236         bh_lock_sock(dccp_v4_ctl_socket->sk);
 237         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 238                                     rxskb->nh.iph->daddr,
 239                                     rxskb->nh.iph->saddr, NULL);
 240         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 241
 242         if (err == NET_XMIT_CN || err == 0) {
 243                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 244                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 245         }
 246 }
 247
 248 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
 249                                  struct dst_entry *dst)
 250 {
 251         int err = -1;
 252         struct sk_buff *skb;
 253
 254         /* First, grab a route. */
 255
 256         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 257                 goto out;
 258
 259         skb = dccp_make_response(sk, dst, req);
 260         if (skb != NULL) {
 261                 const struct inet_request_sock *ireq = inet_rsk(req);
 262                 struct dccp_hdr *dh = dccp_hdr(skb);
 263
 264                 dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
 265                                                       ireq->rmt_addr);
 266                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 267                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 268                                             ireq->rmt_addr,
 269                                             ireq->opt);
 270                 if (err == NET_XMIT_CN)
 271                         err = 0;
 272         }
 273
 274 out:
 275         dst_release(dst);
 276         return err;
 277 }
 278
 279 /*
 280  * This routine is called by the ICMP module when it gets some sort of error
 281  * condition. If err < 0 then the socket should be closed and the error
 282  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 283  * After adjustment header points to the first 8 bytes of the tcp header. We
 284  * need to find the appropriate port.
 285  *
 286  * The locking strategy used here is very "optimistic". When someone else
 287  * accesses the socket the ICMP is just dropped and for some paths there is no
 288  * check at all. A more general error queue to queue errors for later handling
 289  * is probably better.
 290  */
 291 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 292 {
 293         const struct iphdr *iph = (struct iphdr *)skb->data;
 294         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
 295                                                         (iph->ihl << 2));
 296         struct dccp_sock *dp;
 297         struct inet_sock *inet;
 298         const int type = skb->h.icmph->type;
 299         const int code = skb->h.icmph->code;
 300         struct sock *sk;
 301         __u64 seq;
 302         int err;
 303
 304         if (skb->len < (iph->ihl << 2) + 8) {
 305                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 306                 return;
 307         }
 308
 309         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
 310                          iph->saddr, dh->dccph_sport, inet_iif(skb));
 311         if (sk == NULL) {
 312                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 313                 return;
 314         }
 315
 316         if (sk->sk_state == DCCP_TIME_WAIT) {
 317                 inet_twsk_put((struct inet_timewait_sock *)sk);
 318                 return;
 319         }
 320
 321         bh_lock_sock(sk);
 322         /* If too many ICMPs get dropped on busy
 323          * servers this needs to be solved differently.
 324          */
 325         if (sock_owned_by_user(sk))
 326                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 327
 328         if (sk->sk_state == DCCP_CLOSED)
 329                 goto out;
 330
 331         dp = dccp_sk(sk);
 332         seq = dccp_hdr_seq(skb);
 333         if (sk->sk_state != DCCP_LISTEN &&
 334             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
 335                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 336                 goto out;
 337         }
 338
 339         switch (type) {
 340         case ICMP_SOURCE_QUENCH:
 341                 /* Just silently ignore these. */
 342                 goto out;
 343         case ICMP_PARAMETERPROB:
 344                 err = EPROTO;
 345                 break;
 346         case ICMP_DEST_UNREACH:
 347                 if (code > NR_ICMP_UNREACH)
 348                         goto out;
 349
 350                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 351                         if (!sock_owned_by_user(sk))
 352                                 dccp_do_pmtu_discovery(sk, iph, info);
 353                         goto out;
 354                 }
 355
 356                 err = icmp_err_convert[code].errno;
 357                 break;
 358         case ICMP_TIME_EXCEEDED:
 359                 err = EHOSTUNREACH;
 360                 break;
 361         default:
 362                 goto out;
 363         }
 364
 365         switch (sk->sk_state) {
 366                 struct request_sock *req , **prev;
 367         case DCCP_LISTEN:
 368                 if (sock_owned_by_user(sk))
 369                         goto out;
 370                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 371                                           iph->daddr, iph->saddr);
 372                 if (!req)
 373                         goto out;
 374
 375                 /*
 376                  * ICMPs are not backlogged, hence we cannot get an established
 377                  * socket here.
 378                  */
 379                 BUG_TRAP(!req->sk);
 380
 381                 if (seq != dccp_rsk(req)->dreq_iss) {
 382                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 383                         goto out;
 384                 }
 385                 /*
 386                  * Still in RESPOND, just remove it silently.
 387                  * There is no good way to pass the error to the newly
 388                  * created socket, and POSIX does not want network
 389                  * errors returned from accept().
 390                  */
 391                 inet_csk_reqsk_queue_drop(sk, req, prev);
 392                 goto out;
 393
 394         case DCCP_REQUESTING:
 395         case DCCP_RESPOND:
 396                 if (!sock_owned_by_user(sk)) {
 397                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 398                         sk->sk_err = err;
 399
 400                         sk->sk_error_report(sk);
 401
 402                         dccp_done(sk);
 403                 } else
 404                         sk->sk_err_soft = err;
 405                 goto out;
 406         }
 407
 408         /* If we've already connected we will keep trying
 409          * until we time out, or the user gives up.
 410          *
 411          * rfc1122 4.2.3.9 allows to consider as hard errors
 412          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 413          * but it is obsoleted by pmtu discovery).
 414          *
 415          * Note, that in modern internet, where routing is unreliable
 416          * and in each dark corner broken firewalls sit, sending random
 417          * errors ordered by their masters even this two messages finally lose
 418          * their original sense (even Linux sends invalid PORT_UNREACHs)
 419          *
 420          * Now we are in compliance with RFCs.
 421          *                                                      --ANK (980905)
 422          */
 423
 424         inet = inet_sk(sk);
 425         if (!sock_owned_by_user(sk) && inet->recverr) {
 426                 sk->sk_err = err;
 427                 sk->sk_error_report(sk);
 428         } else /* Only an error on timeout */
 429                 sk->sk_err_soft = err;
 430 out:
 431         bh_unlock_sock(sk);
 432         sock_put(sk);
 433 }
 434
 435 /* This routine computes an IPv4 DCCP checksum. */
 436 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
 437 {
 438         const struct inet_sock *inet = inet_sk(sk);
 439         struct dccp_hdr *dh = dccp_hdr(skb);
 440
 441         dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
 442 }
 443
 444 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 445
 446 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
 447                                         const struct sk_buff *skb)
 448 {
 449         return secure_dccp_sequence_number(skb->nh.iph->daddr,
 450                                            skb->nh.iph->saddr,
 451                                            dccp_hdr(skb)->dccph_dport,
 452                                            dccp_hdr(skb)->dccph_sport);
 453 }
 454
 455 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 456 {
 457         struct inet_request_sock *ireq;
 458         struct dccp_sock dp;
 459         struct request_sock *req;
 460         struct dccp_request_sock *dreq;
 461         const __be32 saddr = skb->nh.iph->saddr;
 462         const __be32 daddr = skb->nh.iph->daddr;
 463         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 464         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 465         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
 466
 467         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 468         if (((struct rtable *)skb->dst)->rt_flags &
 469             (RTCF_BROADCAST | RTCF_MULTICAST)) {
 470                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 471                 goto drop;
 472         }
 473
 474         if (dccp_bad_service_code(sk, service)) {
 475                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 476                 goto drop;
 477         }
 478         /*
 479          * TW buckets are converted to open requests without
 480          * limitations, they conserve resources and peer is
 481          * evidently real one.
 482          */
 483         if (inet_csk_reqsk_queue_is_full(sk))
 484                 goto drop;
 485
 486         /*
 487          * Accept backlog is full. If we have already queued enough
 488          * of warm entries in syn queue, drop request. It is better than
 489          * clogging syn queue with openreqs with exponentially increasing
 490          * timeout.
 491          */
 492         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 493                 goto drop;
 494
 495         req = reqsk_alloc(sk->sk_prot->rsk_prot);
 496         if (req == NULL)
 497                 goto drop;
 498
 499         if (dccp_parse_options(sk, skb))
 500                 goto drop_and_free;
 501
 502         dccp_openreq_init(req, &dp, skb);
 503
 504         ireq = inet_rsk(req);
 505         ireq->loc_addr = daddr;
 506         ireq->rmt_addr = saddr;
 507         req->rcv_wnd    = dccp_feat_default_sequence_window;
 508         ireq->opt       = NULL;
 509
 510         /*
 511          * Step 3: Process LISTEN state
 512          *
 513          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 514          *
 515          * In fact we defer setting S.GSR, S.SWL, S.SWH to
 516          * dccp_create_openreq_child.
 517          */
 518         dreq = dccp_rsk(req);
 519         dreq->dreq_isr     = dcb->dccpd_seq;
 520         dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
 521         dreq->dreq_service = service;
 522
 523         if (dccp_v4_send_response(sk, req, NULL))
 524                 goto drop_and_free;
 525
 526         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 527         return 0;
 528
 529 drop_and_free:
 530         reqsk_free(req);
 531 drop:
 532         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 533         dcb->dccpd_reset_code = reset_code;
 534         return -1;
 535 }
 536
 537 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 538
 539 /*
 540  * The three way handshake has completed - we got a valid ACK or DATAACK -
 541  * now create the new socket.
 542  *
 543  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 544  */
 545 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 546                                        struct request_sock *req,
 547                                        struct dst_entry *dst)
 548 {
 549         struct inet_request_sock *ireq;
 550         struct inet_sock *newinet;
 551         struct dccp_sock *newdp;
 552         struct sock *newsk;
 553
 554         if (sk_acceptq_is_full(sk))
 555                 goto exit_overflow;
 556
 557         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
 558                 goto exit;
 559
 560         newsk = dccp_create_openreq_child(sk, req, skb);
 561         if (newsk == NULL)
 562                 goto exit;
 563
 564         sk_setup_caps(newsk, dst);
 565
 566         newdp              = dccp_sk(newsk);
 567         newinet            = inet_sk(newsk);
 568         ireq               = inet_rsk(req);
 569         newinet->daddr     = ireq->rmt_addr;
 570         newinet->rcv_saddr = ireq->loc_addr;
 571         newinet->saddr     = ireq->loc_addr;
 572         newinet->opt       = ireq->opt;
 573         ireq->opt          = NULL;
 574         newinet->mc_index  = inet_iif(skb);
 575         newinet->mc_ttl    = skb->nh.iph->ttl;
 576         newinet->id        = jiffies;
 577
 578         dccp_sync_mss(newsk, dst_mtu(dst));
 579
 580         __inet_hash(&dccp_hashinfo, newsk, 0);
 581         __inet_inherit_port(&dccp_hashinfo, sk, newsk);
 582
 583         return newsk;
 584
 585 exit_overflow:
 586         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
 587 exit:
 588         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
 589         dst_release(dst);
 590         return NULL;
 591 }
 592
 593 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 594
 595 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 596 {
 597         const struct dccp_hdr *dh = dccp_hdr(skb);
 598         const struct iphdr *iph = skb->nh.iph;
 599         struct sock *nsk;
 600         struct request_sock **prev;
 601         /* Find possible connection requests. */
 602         struct request_sock *req = inet_csk_search_req(sk, &prev,
 603                                                        dh->dccph_sport,
 604                                                        iph->saddr, iph->daddr);
 605         if (req != NULL)
 606                 return dccp_check_req(sk, skb, req, prev);
 607
 608         nsk = __inet_lookup_established(&dccp_hashinfo,
 609                                         iph->saddr, dh->dccph_sport,
 610                                         iph->daddr, ntohs(dh->dccph_dport),
 611                                         inet_iif(skb));
 612         if (nsk != NULL) {
 613                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 614                         bh_lock_sock(nsk);
 615                         return nsk;
 616                 }
 617                 inet_twsk_put((struct inet_timewait_sock *)nsk);
 618                 return NULL;
 619         }
 620
 621         return sk;
 622 }
 623
 624 int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
 625                      const __be32 daddr)
 626 {
 627         const struct dccp_hdr* dh = dccp_hdr(skb);
 628         int checksum_len;
 629         u32 tmp;
 630
 631         if (dh->dccph_cscov == 0)
 632                 checksum_len = skb->len;
 633         else {
 634                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 635                 checksum_len = checksum_len < skb->len ? checksum_len :
 636                                                          skb->len;
 637         }
 638
 639         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 640         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 641                                  IPPROTO_DCCP, tmp);
 642 }
 643
 644 EXPORT_SYMBOL_GPL(dccp_v4_checksum);
 645
 646 static int dccp_v4_verify_checksum(struct sk_buff *skb,
 647                                    const __be32 saddr, const __be32 daddr)
 648 {
 649         struct dccp_hdr *dh = dccp_hdr(skb);
 650         int checksum_len;
 651         u32 tmp;
 652
 653         if (dh->dccph_cscov == 0)
 654                 checksum_len = skb->len;
 655         else {
 656                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
 657                 checksum_len = checksum_len < skb->len ? checksum_len :
 658                                                          skb->len;
 659         }
 660         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
 661         return csum_tcpudp_magic(saddr, daddr, checksum_len,
 662                                  IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
 663 }
 664
 665 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
 666                                            struct sk_buff *skb)
 667 {
 668         struct rtable *rt;
 669         struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
 670                             .nl_u = { .ip4_u =
 671                                       { .daddr = skb->nh.iph->saddr,
 672                                         .saddr = skb->nh.iph->daddr,
 673                                         .tos = RT_CONN_FLAGS(sk) } },
 674                             .proto = sk->sk_protocol,
 675                             .uli_u = { .ports =
 676                                        { .sport = dccp_hdr(skb)->dccph_dport,
 677                                          .dport = dccp_hdr(skb)->dccph_sport }
 678                                      }
 679                           };
 680
 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         skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
 721         dh = dccp_hdr(skb);
 722         memset(dh, 0, dccp_hdr_reset_len);
 723
 724         /* Build DCCP header and checksum it. */
 725         dh->dccph_type     = DCCP_PKT_RESET;
 726         dh->dccph_sport    = rxdh->dccph_dport;
 727         dh->dccph_dport    = rxdh->dccph_sport;
 728         dh->dccph_doff     = dccp_hdr_reset_len / 4;
 729         dh->dccph_x        = 1;
 730         dccp_hdr_reset(skb)->dccph_reset_code =
 731                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 732
 733         /* See "8.3.1. Abnormal Termination" in draft-ietf-dccp-spec-11 */
 734         seqno = 0;
 735         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 736                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 737
 738         dccp_hdr_set_seq(dh, seqno);
 739         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
 740                          DCCP_SKB_CB(rxskb)->dccpd_seq);
 741
 742         dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
 743                                               rxskb->nh.iph->daddr);
 744
 745         bh_lock_sock(dccp_v4_ctl_socket->sk);
 746         err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
 747                                     rxskb->nh.iph->daddr,
 748                                     rxskb->nh.iph->saddr, NULL);
 749         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 750
 751         if (err == NET_XMIT_CN || err == 0) {
 752                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 753                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 754         }
 755 out:
 756          dst_release(dst);
 757 }
 758
 759 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 760 {
 761         struct dccp_hdr *dh = dccp_hdr(skb);
 762
 763         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 764                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 765                         goto reset;
 766                 return 0;
 767         }
 768
 769         /*
 770          *  Step 3: Process LISTEN state
 771          *     If S.state == LISTEN,
 772          *        If P.type == Request or P contains a valid Init Cookie
 773          *              option,
 774          *           * Must scan the packet's options to check for an Init
 775          *              Cookie.  Only the Init Cookie is processed here,
 776          *              however; other options are processed in Step 8.  This
 777          *              scan need only be performed if the endpoint uses Init
 778          *              Cookies *
 779          *           * Generate a new socket and switch to that socket *
 780          *           Set S := new socket for this port pair
 781          *           S.state = RESPOND
 782          *           Choose S.ISS (initial seqno) or set from Init Cookie
 783          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 784          *           Continue with S.state == RESPOND
 785          *           * A Response packet will be generated in Step 11 *
 786          *        Otherwise,
 787          *           Generate Reset(No Connection) unless P.type == Reset
 788          *           Drop packet and return
 789          *
 790          * NOTE: the check for the packet types is done in
 791          *       dccp_rcv_state_process
 792          */
 793         if (sk->sk_state == DCCP_LISTEN) {
 794                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 795
 796                 if (nsk == NULL)
 797                         goto discard;
 798
 799                 if (nsk != sk) {
 800                         if (dccp_child_process(sk, nsk, skb))
 801                                 goto reset;
 802                         return 0;
 803                 }
 804         }
 805
 806         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 807                 goto reset;
 808         return 0;
 809
 810 reset:
 811         dccp_v4_ctl_send_reset(skb);
 812 discard:
 813         kfree_skb(skb);
 814         return 0;
 815 }
 816
 817 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 818
 819 int dccp_invalid_packet(struct sk_buff *skb)
 820 {
 821         const struct dccp_hdr *dh;
 822
 823         if (skb->pkt_type != PACKET_HOST)
 824                 return 1;
 825
 826         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 827                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
 828                 return 1;
 829         }
 830
 831         dh = dccp_hdr(skb);
 832
 833         /* If the packet type is not understood, drop packet and return */
 834         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 835                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
 836                 return 1;
 837         }
 838
 839         /*
 840          * If P.Data Offset is too small for packet type, or too large for
 841          * packet, drop packet and return
 842          */
 843         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 844                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 845                                             "too small 1\n",
 846                                dh->dccph_doff);
 847                 return 1;
 848         }
 849
 850         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 851                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
 852                                             "too small 2\n",
 853                                dh->dccph_doff);
 854                 return 1;
 855         }
 856
 857         dh = dccp_hdr(skb);
 858
 859         /*
 860          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 861          * has short sequence numbers), drop packet and return
 862          */
 863         if (dh->dccph_x == 0 &&
 864             dh->dccph_type != DCCP_PKT_DATA &&
 865             dh->dccph_type != DCCP_PKT_ACK &&
 866             dh->dccph_type != DCCP_PKT_DATAACK) {
 867                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
 868                                             "nor DataAck and P.X == 0\n",
 869                                dccp_packet_name(dh->dccph_type));
 870                 return 1;
 871         }
 872
 873         return 0;
 874 }
 875
 876 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 877
 878 /* this is called when real data arrives */
 879 static int dccp_v4_rcv(struct sk_buff *skb)
 880 {
 881         const struct dccp_hdr *dh;
 882         struct sock *sk;
 883
 884         /* Step 1: Check header basics: */
 885
 886         if (dccp_invalid_packet(skb))
 887                 goto discard_it;
 888
 889         /* If the header checksum is incorrect, drop packet and return */
 890         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
 891                                     skb->nh.iph->daddr) < 0) {
 892                 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
 893                                __FUNCTION__);
 894                 goto discard_it;
 895         }
 896
 897         dh = dccp_hdr(skb);
 898
 899         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
 900         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 901
 902         dccp_pr_debug("%8.8s "
 903                       "src=%u.%u.%u.%u@%-5d "
 904                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
 905                       dccp_packet_name(dh->dccph_type),
 906                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
 907                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
 908                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 909
 910         if (dccp_packet_without_ack(skb)) {
 911                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 912                 dccp_pr_debug_cat("\n");
 913         } else {
 914                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 915                 dccp_pr_debug_cat(", ack=%llu\n",
 916                                   (unsigned long long)
 917                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 918         }
 919
 920         /* Step 2:
 921          *      Look up flow ID in table and get corresponding socket */
 922         sk = __inet_lookup(&dccp_hashinfo,
 923                            skb->nh.iph->saddr, dh->dccph_sport,
 924                            skb->nh.iph->daddr, ntohs(dh->dccph_dport),
 925                            inet_iif(skb));
 926
 927         /*
 928          * Step 2:
 929          *      If no socket ...
 930          *              Generate Reset(No Connection) unless P.type == Reset
 931          *              Drop packet and return
 932          */
 933         if (sk == NULL) {
 934                 dccp_pr_debug("failed to look up flow ID in table and "
 935                               "get corresponding socket\n");
 936                 goto no_dccp_socket;
 937         }
 938
 939         /*
 940          * Step 2:
 941          *      ... or S.state == TIMEWAIT,
 942          *              Generate Reset(No Connection) unless P.type == Reset
 943          *              Drop packet and return
 944          */
 945
 946         if (sk->sk_state == DCCP_TIME_WAIT) {
 947                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
 948                               "do_time_wait\n");
 949                 goto do_time_wait;
 950         }
 951
 952         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 953                 goto discard_and_relse;
 954         nf_reset(skb);
 955
 956         return sk_receive_skb(sk, skb);
 957
 958 no_dccp_socket:
 959         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 960                 goto discard_it;
 961         /*
 962          * Step 2:
 963          *              Generate Reset(No Connection) unless P.type == Reset
 964          *              Drop packet and return
 965          */
 966         if (dh->dccph_type != DCCP_PKT_RESET) {
 967                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 968                                         DCCP_RESET_CODE_NO_CONNECTION;
 969                 dccp_v4_ctl_send_reset(skb);
 970         }
 971
 972 discard_it:
 973         /* Discard frame. */
 974         kfree_skb(skb);
 975         return 0;
 976
 977 discard_and_relse:
 978         sock_put(sk);
 979         goto discard_it;
 980
 981 do_time_wait:
 982         inet_twsk_put((struct inet_timewait_sock *)sk);
 983         goto no_dccp_socket;
 984 }
 985
 986 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 987         .queue_xmit        = ip_queue_xmit,
 988         .send_check        = dccp_v4_send_check,
 989         .rebuild_header    = inet_sk_rebuild_header,
 990         .conn_request      = dccp_v4_conn_request,
 991         .syn_recv_sock     = dccp_v4_request_recv_sock,
 992         .net_header_len    = sizeof(struct iphdr),
 993         .setsockopt        = ip_setsockopt,
 994         .getsockopt        = ip_getsockopt,
 995         .addr2sockaddr     = inet_csk_addr2sockaddr,
 996         .sockaddr_len      = sizeof(struct sockaddr_in),
 997 #ifdef CONFIG_COMPAT
 998         .compat_setsockopt = compat_ip_setsockopt,
 999         .compat_getsockopt = compat_ip_getsockopt,
1000 #endif
1001 };
1002
1003 static int dccp_v4_init_sock(struct sock *sk)
1004 {
1005         static __u8 dccp_v4_ctl_sock_initialized;
1006         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
1007
1008         if (err == 0) {
1009                 if (unlikely(!dccp_v4_ctl_sock_initialized))
1010                         dccp_v4_ctl_sock_initialized = 1;
1011                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
1012         }
1013
1014         return err;
1015 }
1016
1017 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1018 {
1019         kfree(inet_rsk(req)->opt);
1020 }
1021
1022 static struct request_sock_ops dccp_request_sock_ops = {
1023         .family         = PF_INET,
1024         .obj_size       = sizeof(struct dccp_request_sock),
1025         .rtx_syn_ack    = dccp_v4_send_response,
1026         .send_ack       = dccp_v4_reqsk_send_ack,
1027         .destructor     = dccp_v4_reqsk_destructor,
1028         .send_reset     = dccp_v4_ctl_send_reset,
1029 };
1030
1031 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1032         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
1033 };
1034
1035 static struct proto dccp_v4_prot = {
1036         .name                   = "DCCP",
1037         .owner                  = THIS_MODULE,
1038         .close                  = dccp_close,
1039         .connect                = dccp_v4_connect,
1040         .disconnect             = dccp_disconnect,
1041         .ioctl                  = dccp_ioctl,
1042         .init                   = dccp_v4_init_sock,
1043         .setsockopt             = dccp_setsockopt,
1044         .getsockopt             = dccp_getsockopt,
1045         .sendmsg                = dccp_sendmsg,
1046         .recvmsg                = dccp_recvmsg,
1047         .backlog_rcv            = dccp_v4_do_rcv,
1048         .hash                   = dccp_hash,
1049         .unhash                 = dccp_unhash,
1050         .accept                 = inet_csk_accept,
1051         .get_port               = dccp_v4_get_port,
1052         .shutdown               = dccp_shutdown,
1053         .destroy                = dccp_destroy_sock,
1054         .orphan_count           = &dccp_orphan_count,
1055         .max_header             = MAX_DCCP_HEADER,
1056         .obj_size               = sizeof(struct dccp_sock),
1057         .rsk_prot               = &dccp_request_sock_ops,
1058         .twsk_prot              = &dccp_timewait_sock_ops,
1059 #ifdef CONFIG_COMPAT
1060         .compat_setsockopt      = compat_dccp_setsockopt,
1061         .compat_getsockopt      = compat_dccp_getsockopt,
1062 #endif
1063 };
1064
1065 static struct net_protocol dccp_v4_protocol = {
1066         .handler        = dccp_v4_rcv,
1067         .err_handler    = dccp_v4_err,
1068         .no_policy      = 1,
1069 };
1070
1071 static const struct proto_ops inet_dccp_ops = {
1072         .family            = PF_INET,
1073         .owner             = THIS_MODULE,
1074         .release           = inet_release,
1075         .bind              = inet_bind,
1076         .connect           = inet_stream_connect,
1077         .socketpair        = sock_no_socketpair,
1078         .accept            = inet_accept,
1079         .getname           = inet_getname,
1080         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1081         .poll              = dccp_poll,
1082         .ioctl             = inet_ioctl,
1083         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1084         .listen            = inet_dccp_listen,
1085         .shutdown          = inet_shutdown,
1086         .setsockopt        = sock_common_setsockopt,
1087         .getsockopt        = sock_common_getsockopt,
1088         .sendmsg           = inet_sendmsg,
1089         .recvmsg           = sock_common_recvmsg,
1090         .mmap              = sock_no_mmap,
1091         .sendpage          = sock_no_sendpage,
1092 #ifdef CONFIG_COMPAT
1093         .compat_setsockopt = compat_sock_common_setsockopt,
1094         .compat_getsockopt = compat_sock_common_getsockopt,
1095 #endif
1096 };
1097
1098 static struct inet_protosw dccp_v4_protosw = {
1099         .type           = SOCK_DCCP,
1100         .protocol       = IPPROTO_DCCP,
1101         .prot           = &dccp_v4_prot,
1102         .ops            = &inet_dccp_ops,
1103         .capability     = -1,
1104         .no_check       = 0,
1105         .flags          = INET_PROTOSW_ICSK,
1106 };
1107
1108 static int __init dccp_v4_init(void)
1109 {
1110         int err = proto_register(&dccp_v4_prot, 1);
1111
1112         if (err != 0)
1113                 goto out;
1114
1115         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1116         if (err != 0)
1117                 goto out_proto_unregister;
1118
1119         inet_register_protosw(&dccp_v4_protosw);
1120
1121         err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1122                                        SOCK_DCCP, IPPROTO_DCCP);
1123         if (err)
1124                 goto out_unregister_protosw;
1125 out:
1126         return err;
1127 out_unregister_protosw:
1128         inet_unregister_protosw(&dccp_v4_protosw);
1129         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1130 out_proto_unregister:
1131         proto_unregister(&dccp_v4_prot);
1132         goto out;
1133 }
1134
1135 static void __exit dccp_v4_exit(void)
1136 {
1137         inet_unregister_protosw(&dccp_v4_protosw);
1138         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1139         proto_unregister(&dccp_v4_prot);
1140 }
1141
1142 module_init(dccp_v4_init);
1143 module_exit(dccp_v4_exit);
1144
1145 /*
1146  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1147  * values directly, Also cover the case where the protocol is not specified,
1148  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1149  */
1150 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
1151 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
1152 MODULE_LICENSE("GPL");
1153 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1154 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");