Pileus Git - ~andy/linux/blob - 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/slab.h>
  16 #include <linux/module.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/random.h>
  19
  20 #include <net/icmp.h>
  21 #include <net/inet_common.h>
  22 #include <net/inet_hashtables.h>
  23 #include <net/inet_sock.h>
  24 #include <net/protocol.h>
  25 #include <net/sock.h>
  26 #include <net/timewait_sock.h>
  27 #include <net/tcp_states.h>
  28 #include <net/xfrm.h>
  29 #include <net/secure_seq.h>
  30
  31 #include "ackvec.h"
  32 #include "ccid.h"
  33 #include "dccp.h"
  34 #include "feat.h"
  35
  36 /*
  37  * The per-net dccp.v4_ctl_sk socket is used for responding to
  38  * the Out-of-the-blue (OOTB) packets. A control sock will be created
  39  * for this socket at the initialization time.
  40  */
  41
  42 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  43 {
  44         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  45         struct inet_sock *inet = inet_sk(sk);
  46         struct dccp_sock *dp = dccp_sk(sk);
  47         __be16 orig_sport, orig_dport;
  48         __be32 daddr, nexthop;
  49         struct flowi4 *fl4;
  50         struct rtable *rt;
  51         int err;
  52         struct ip_options_rcu *inet_opt;
  53
  54         dp->dccps_role = DCCP_ROLE_CLIENT;
  55
  56         if (addr_len < sizeof(struct sockaddr_in))
  57                 return -EINVAL;
  58
  59         if (usin->sin_family != AF_INET)
  60                 return -EAFNOSUPPORT;
  61
  62         nexthop = daddr = usin->sin_addr.s_addr;
  63
  64         inet_opt = rcu_dereference_protected(inet->inet_opt,
  65                                              sock_owned_by_user(sk));
  66         if (inet_opt != NULL && inet_opt->opt.srr) {
  67                 if (daddr == 0)
  68                         return -EINVAL;
  69                 nexthop = inet_opt->opt.faddr;
  70         }
  71
  72         orig_sport = inet->inet_sport;
  73         orig_dport = usin->sin_port;
  74         fl4 = &inet->cork.fl.u.ip4;
  75         rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
  76                               RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  77                               IPPROTO_DCCP,
  78                               orig_sport, orig_dport, sk);
  79         if (IS_ERR(rt))
  80                 return PTR_ERR(rt);
  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->opt.srr)
  88                 daddr = fl4->daddr;
  89
  90         if (inet->inet_saddr == 0)
  91                 inet->inet_saddr = fl4->saddr;
  92         inet->inet_rcv_saddr = inet->inet_saddr;
  93
  94         inet->inet_dport = usin->sin_port;
  95         inet->inet_daddr = daddr;
  96
  97         inet_csk(sk)->icsk_ext_hdr_len = 0;
  98         if (inet_opt)
  99                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->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         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 112                                inet->inet_sport, inet->inet_dport, sk);
 113         if (IS_ERR(rt)) {
 114                 err = PTR_ERR(rt);
 115                 rt = NULL;
 116                 goto failure;
 117         }
 118         /* OK, now commit destination to socket.  */
 119         sk_setup_caps(sk, &rt->dst);
 120
 121         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 122                                                     inet->inet_daddr,
 123                                                     inet->inet_sport,
 124                                                     inet->inet_dport);
 125         inet->inet_id = dp->dccps_iss ^ jiffies;
 126
 127         err = dccp_connect(sk);
 128         rt = NULL;
 129         if (err != 0)
 130                 goto failure;
 131 out:
 132         return err;
 133 failure:
 134         /*
 135          * This unhashes the socket and releases the local port, if necessary.
 136          */
 137         dccp_set_state(sk, DCCP_CLOSED);
 138         ip_rt_put(rt);
 139         sk->sk_route_caps = 0;
 140         inet->inet_dport = 0;
 141         goto out;
 142 }
 143
 144 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 145
 146 /*
 147  * This routine does path mtu discovery as defined in RFC1191.
 148  */
 149 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 150                                           const struct iphdr *iph,
 151                                           u32 mtu)
 152 {
 153         struct dst_entry *dst;
 154         const struct inet_sock *inet = inet_sk(sk);
 155         const struct dccp_sock *dp = dccp_sk(sk);
 156
 157         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 158          * send out by Linux are always < 576bytes so they should go through
 159          * unfragmented).
 160          */
 161         if (sk->sk_state == DCCP_LISTEN)
 162                 return;
 163
 164         dst = inet_csk_update_pmtu(sk, mtu);
 165         if (!dst)
 166                 return;
 167
 168         /* Something is about to be wrong... Remember soft error
 169          * for the case, if this connection will not able to recover.
 170          */
 171         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 172                 sk->sk_err_soft = EMSGSIZE;
 173
 174         mtu = dst_mtu(dst);
 175
 176         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 177             ip_sk_accept_pmtu(sk) &&
 178             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 179                 dccp_sync_mss(sk, mtu);
 180
 181                 /*
 182                  * From RFC 4340, sec. 14.1:
 183                  *
 184                  *      DCCP-Sync packets are the best choice for upward
 185                  *      probing, since DCCP-Sync probes do not risk application
 186                  *      data loss.
 187                  */
 188                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 189         } /* else let the usual retransmit timer handle it */
 190 }
 191
 192 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
 193 {
 194         struct dst_entry *dst = __sk_dst_check(sk, 0);
 195
 196         if (dst)
 197                 dst->ops->redirect(dst, sk, skb);
 198 }
 199
 200 /*
 201  * This routine is called by the ICMP module when it gets some sort of error
 202  * condition. If err < 0 then the socket should be closed and the error
 203  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 204  * After adjustment header points to the first 8 bytes of the tcp header. We
 205  * need to find the appropriate port.
 206  *
 207  * The locking strategy used here is very "optimistic". When someone else
 208  * accesses the socket the ICMP is just dropped and for some paths there is no
 209  * check at all. A more general error queue to queue errors for later handling
 210  * is probably better.
 211  */
 212 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 213 {
 214         const struct iphdr *iph = (struct iphdr *)skb->data;
 215         const u8 offset = iph->ihl << 2;
 216         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
 217         struct dccp_sock *dp;
 218         struct inet_sock *inet;
 219         const int type = icmp_hdr(skb)->type;
 220         const int code = icmp_hdr(skb)->code;
 221         struct sock *sk;
 222         __u64 seq;
 223         int err;
 224         struct net *net = dev_net(skb->dev);
 225
 226         if (skb->len < offset + sizeof(*dh) ||
 227             skb->len < offset + __dccp_basic_hdr_len(dh)) {
 228                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 229                 return;
 230         }
 231
 232         sk = inet_lookup(net, &dccp_hashinfo,
 233                         iph->daddr, dh->dccph_dport,
 234                         iph->saddr, dh->dccph_sport, inet_iif(skb));
 235         if (sk == NULL) {
 236                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 237                 return;
 238         }
 239
 240         if (sk->sk_state == DCCP_TIME_WAIT) {
 241                 inet_twsk_put(inet_twsk(sk));
 242                 return;
 243         }
 244
 245         bh_lock_sock(sk);
 246         /* If too many ICMPs get dropped on busy
 247          * servers this needs to be solved differently.
 248          */
 249         if (sock_owned_by_user(sk))
 250                 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 251
 252         if (sk->sk_state == DCCP_CLOSED)
 253                 goto out;
 254
 255         dp = dccp_sk(sk);
 256         seq = dccp_hdr_seq(dh);
 257         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 258             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 259                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 260                 goto out;
 261         }
 262
 263         switch (type) {
 264         case ICMP_REDIRECT:
 265                 dccp_do_redirect(skb, sk);
 266                 goto out;
 267         case ICMP_SOURCE_QUENCH:
 268                 /* Just silently ignore these. */
 269                 goto out;
 270         case ICMP_PARAMETERPROB:
 271                 err = EPROTO;
 272                 break;
 273         case ICMP_DEST_UNREACH:
 274                 if (code > NR_ICMP_UNREACH)
 275                         goto out;
 276
 277                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 278                         if (!sock_owned_by_user(sk))
 279                                 dccp_do_pmtu_discovery(sk, iph, info);
 280                         goto out;
 281                 }
 282
 283                 err = icmp_err_convert[code].errno;
 284                 break;
 285         case ICMP_TIME_EXCEEDED:
 286                 err = EHOSTUNREACH;
 287                 break;
 288         default:
 289                 goto out;
 290         }
 291
 292         switch (sk->sk_state) {
 293                 struct request_sock *req , **prev;
 294         case DCCP_LISTEN:
 295                 if (sock_owned_by_user(sk))
 296                         goto out;
 297                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
 298                                           iph->daddr, iph->saddr);
 299                 if (!req)
 300                         goto out;
 301
 302                 /*
 303                  * ICMPs are not backlogged, hence we cannot get an established
 304                  * socket here.
 305                  */
 306                 WARN_ON(req->sk);
 307
 308                 if (!between48(seq, dccp_rsk(req)->dreq_iss,
 309                                     dccp_rsk(req)->dreq_gss)) {
 310                         NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 311                         goto out;
 312                 }
 313                 /*
 314                  * Still in RESPOND, just remove it silently.
 315                  * There is no good way to pass the error to the newly
 316                  * created socket, and POSIX does not want network
 317                  * errors returned from accept().
 318                  */
 319                 inet_csk_reqsk_queue_drop(sk, req, prev);
 320                 goto out;
 321
 322         case DCCP_REQUESTING:
 323         case DCCP_RESPOND:
 324                 if (!sock_owned_by_user(sk)) {
 325                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 326                         sk->sk_err = err;
 327
 328                         sk->sk_error_report(sk);
 329
 330                         dccp_done(sk);
 331                 } else
 332                         sk->sk_err_soft = err;
 333                 goto out;
 334         }
 335
 336         /* If we've already connected we will keep trying
 337          * until we time out, or the user gives up.
 338          *
 339          * rfc1122 4.2.3.9 allows to consider as hard errors
 340          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 341          * but it is obsoleted by pmtu discovery).
 342          *
 343          * Note, that in modern internet, where routing is unreliable
 344          * and in each dark corner broken firewalls sit, sending random
 345          * errors ordered by their masters even this two messages finally lose
 346          * their original sense (even Linux sends invalid PORT_UNREACHs)
 347          *
 348          * Now we are in compliance with RFCs.
 349          *                                                      --ANK (980905)
 350          */
 351
 352         inet = inet_sk(sk);
 353         if (!sock_owned_by_user(sk) && inet->recverr) {
 354                 sk->sk_err = err;
 355                 sk->sk_error_report(sk);
 356         } else /* Only an error on timeout */
 357                 sk->sk_err_soft = err;
 358 out:
 359         bh_unlock_sock(sk);
 360         sock_put(sk);
 361 }
 362
 363 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 364                                       __be32 src, __be32 dst)
 365 {
 366         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 367 }
 368
 369 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 370 {
 371         const struct inet_sock *inet = inet_sk(sk);
 372         struct dccp_hdr *dh = dccp_hdr(skb);
 373
 374         dccp_csum_outgoing(skb);
 375         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 376                                                  inet->inet_saddr,
 377                                                  inet->inet_daddr);
 378 }
 379
 380 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 381
 382 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 383 {
 384         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 385                                            ip_hdr(skb)->saddr,
 386                                            dccp_hdr(skb)->dccph_dport,
 387                                            dccp_hdr(skb)->dccph_sport);
 388 }
 389
 390 /*
 391  * The three way handshake has completed - we got a valid ACK or DATAACK -
 392  * now create the new socket.
 393  *
 394  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 395  */
 396 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 397                                        struct request_sock *req,
 398                                        struct dst_entry *dst)
 399 {
 400         struct inet_request_sock *ireq;
 401         struct inet_sock *newinet;
 402         struct sock *newsk;
 403
 404         if (sk_acceptq_is_full(sk))
 405                 goto exit_overflow;
 406
 407         newsk = dccp_create_openreq_child(sk, req, skb);
 408         if (newsk == NULL)
 409                 goto exit_nonewsk;
 410
 411         newinet            = inet_sk(newsk);
 412         ireq               = inet_rsk(req);
 413         newinet->inet_daddr     = ireq->ir_rmt_addr;
 414         newinet->inet_rcv_saddr = ireq->ir_loc_addr;
 415         newinet->inet_saddr     = ireq->ir_loc_addr;
 416         newinet->inet_opt       = ireq->opt;
 417         ireq->opt          = NULL;
 418         newinet->mc_index  = inet_iif(skb);
 419         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 420         newinet->inet_id   = jiffies;
 421
 422         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 423                 goto put_and_exit;
 424
 425         sk_setup_caps(newsk, dst);
 426
 427         dccp_sync_mss(newsk, dst_mtu(dst));
 428
 429         if (__inet_inherit_port(sk, newsk) < 0)
 430                 goto put_and_exit;
 431         __inet_hash_nolisten(newsk, NULL);
 432
 433         return newsk;
 434
 435 exit_overflow:
 436         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 437 exit_nonewsk:
 438         dst_release(dst);
 439 exit:
 440         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 441         return NULL;
 442 put_and_exit:
 443         inet_csk_prepare_forced_close(newsk);
 444         dccp_done(newsk);
 445         goto exit;
 446 }
 447
 448 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 449
 450 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 451 {
 452         const struct dccp_hdr *dh = dccp_hdr(skb);
 453         const struct iphdr *iph = ip_hdr(skb);
 454         struct sock *nsk;
 455         struct request_sock **prev;
 456         /* Find possible connection requests. */
 457         struct request_sock *req = inet_csk_search_req(sk, &prev,
 458                                                        dh->dccph_sport,
 459                                                        iph->saddr, iph->daddr);
 460         if (req != NULL)
 461                 return dccp_check_req(sk, skb, req, prev);
 462
 463         nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
 464                                       iph->saddr, dh->dccph_sport,
 465                                       iph->daddr, dh->dccph_dport,
 466                                       inet_iif(skb));
 467         if (nsk != NULL) {
 468                 if (nsk->sk_state != DCCP_TIME_WAIT) {
 469                         bh_lock_sock(nsk);
 470                         return nsk;
 471                 }
 472                 inet_twsk_put(inet_twsk(nsk));
 473                 return NULL;
 474         }
 475
 476         return sk;
 477 }
 478
 479 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 480                                            struct sk_buff *skb)
 481 {
 482         struct rtable *rt;
 483         const struct iphdr *iph = ip_hdr(skb);
 484         struct flowi4 fl4 = {
 485                 .flowi4_oif = inet_iif(skb),
 486                 .daddr = iph->saddr,
 487                 .saddr = iph->daddr,
 488                 .flowi4_tos = RT_CONN_FLAGS(sk),
 489                 .flowi4_proto = sk->sk_protocol,
 490                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 491                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 492         };
 493
 494         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 495         rt = ip_route_output_flow(net, &fl4, sk);
 496         if (IS_ERR(rt)) {
 497                 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 498                 return NULL;
 499         }
 500
 501         return &rt->dst;
 502 }
 503
 504 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
 505 {
 506         int err = -1;
 507         struct sk_buff *skb;
 508         struct dst_entry *dst;
 509         struct flowi4 fl4;
 510
 511         dst = inet_csk_route_req(sk, &fl4, req);
 512         if (dst == NULL)
 513                 goto out;
 514
 515         skb = dccp_make_response(sk, dst, req);
 516         if (skb != NULL) {
 517                 const struct inet_request_sock *ireq = inet_rsk(req);
 518                 struct dccp_hdr *dh = dccp_hdr(skb);
 519
 520                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 521                                                               ireq->ir_rmt_addr);
 522                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 523                                             ireq->ir_rmt_addr,
 524                                             ireq->opt);
 525                 err = net_xmit_eval(err);
 526         }
 527
 528 out:
 529         dst_release(dst);
 530         return err;
 531 }
 532
 533 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
 534 {
 535         int err;
 536         const struct iphdr *rxiph;
 537         struct sk_buff *skb;
 538         struct dst_entry *dst;
 539         struct net *net = dev_net(skb_dst(rxskb)->dev);
 540         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
 541
 542         /* Never send a reset in response to a reset. */
 543         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 544                 return;
 545
 546         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 547                 return;
 548
 549         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 550         if (dst == NULL)
 551                 return;
 552
 553         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 554         if (skb == NULL)
 555                 goto out;
 556
 557         rxiph = ip_hdr(rxskb);
 558         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 559                                                                  rxiph->daddr);
 560         skb_dst_set(skb, dst_clone(dst));
 561
 562         bh_lock_sock(ctl_sk);
 563         err = ip_build_and_send_pkt(skb, ctl_sk,
 564                                     rxiph->daddr, rxiph->saddr, NULL);
 565         bh_unlock_sock(ctl_sk);
 566
 567         if (net_xmit_eval(err) == 0) {
 568                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 569                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 570         }
 571 out:
 572          dst_release(dst);
 573 }
 574
 575 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 576 {
 577         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 578         kfree(inet_rsk(req)->opt);
 579 }
 580
 581 void dccp_syn_ack_timeout(struct sock *sk, struct request_sock *req)
 582 {
 583 }
 584 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 585
 586 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 587         .family         = PF_INET,
 588         .obj_size       = sizeof(struct dccp_request_sock),
 589         .rtx_syn_ack    = dccp_v4_send_response,
 590         .send_ack       = dccp_reqsk_send_ack,
 591         .destructor     = dccp_v4_reqsk_destructor,
 592         .send_reset     = dccp_v4_ctl_send_reset,
 593         .syn_ack_timeout = dccp_syn_ack_timeout,
 594 };
 595
 596 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 597 {
 598         struct inet_request_sock *ireq;
 599         struct request_sock *req;
 600         struct dccp_request_sock *dreq;
 601         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 602         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 603
 604         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 605         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 606                 return 0;       /* discard, don't send a reset here */
 607
 608         if (dccp_bad_service_code(sk, service)) {
 609                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 610                 goto drop;
 611         }
 612         /*
 613          * TW buckets are converted to open requests without
 614          * limitations, they conserve resources and peer is
 615          * evidently real one.
 616          */
 617         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 618         if (inet_csk_reqsk_queue_is_full(sk))
 619                 goto drop;
 620
 621         /*
 622          * Accept backlog is full. If we have already queued enough
 623          * of warm entries in syn queue, drop request. It is better than
 624          * clogging syn queue with openreqs with exponentially increasing
 625          * timeout.
 626          */
 627         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 628                 goto drop;
 629
 630         req = inet_reqsk_alloc(&dccp_request_sock_ops);
 631         if (req == NULL)
 632                 goto drop;
 633
 634         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 635                 goto drop_and_free;
 636
 637         dreq = dccp_rsk(req);
 638         if (dccp_parse_options(sk, dreq, skb))
 639                 goto drop_and_free;
 640
 641         if (security_inet_conn_request(sk, skb, req))
 642                 goto drop_and_free;
 643
 644         ireq = inet_rsk(req);
 645         ireq->ir_loc_addr = ip_hdr(skb)->daddr;
 646         ireq->ir_rmt_addr = ip_hdr(skb)->saddr;
 647
 648         /*
 649          * Step 3: Process LISTEN state
 650          *
 651          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 652          *
 653          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 654          */
 655         dreq->dreq_isr     = dcb->dccpd_seq;
 656         dreq->dreq_gsr     = dreq->dreq_isr;
 657         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 658         dreq->dreq_gss     = dreq->dreq_iss;
 659         dreq->dreq_service = service;
 660
 661         if (dccp_v4_send_response(sk, req))
 662                 goto drop_and_free;
 663
 664         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 665         return 0;
 666
 667 drop_and_free:
 668         reqsk_free(req);
 669 drop:
 670         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
 671         return -1;
 672 }
 673
 674 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 675
 676 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 677 {
 678         struct dccp_hdr *dh = dccp_hdr(skb);
 679
 680         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 681                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 682                         goto reset;
 683                 return 0;
 684         }
 685
 686         /*
 687          *  Step 3: Process LISTEN state
 688          *       If P.type == Request or P contains a valid Init Cookie option,
 689          *            (* Must scan the packet's options to check for Init
 690          *               Cookies.  Only Init Cookies are processed here,
 691          *               however; other options are processed in Step 8.  This
 692          *               scan need only be performed if the endpoint uses Init
 693          *               Cookies *)
 694          *            (* Generate a new socket and switch to that socket *)
 695          *            Set S := new socket for this port pair
 696          *            S.state = RESPOND
 697          *            Choose S.ISS (initial seqno) or set from Init Cookies
 698          *            Initialize S.GAR := S.ISS
 699          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 700          *            Continue with S.state == RESPOND
 701          *            (* A Response packet will be generated in Step 11 *)
 702          *       Otherwise,
 703          *            Generate Reset(No Connection) unless P.type == Reset
 704          *            Drop packet and return
 705          *
 706          * NOTE: the check for the packet types is done in
 707          *       dccp_rcv_state_process
 708          */
 709         if (sk->sk_state == DCCP_LISTEN) {
 710                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
 711
 712                 if (nsk == NULL)
 713                         goto discard;
 714
 715                 if (nsk != sk) {
 716                         if (dccp_child_process(sk, nsk, skb))
 717                                 goto reset;
 718                         return 0;
 719                 }
 720         }
 721
 722         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 723                 goto reset;
 724         return 0;
 725
 726 reset:
 727         dccp_v4_ctl_send_reset(sk, skb);
 728 discard:
 729         kfree_skb(skb);
 730         return 0;
 731 }
 732
 733 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 734
 735 /**
 736  *      dccp_invalid_packet  -  check for malformed packets
 737  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 738  *      Packets that fail these checks are ignored and do not receive Resets.
 739  */
 740 int dccp_invalid_packet(struct sk_buff *skb)
 741 {
 742         const struct dccp_hdr *dh;
 743         unsigned int cscov;
 744
 745         if (skb->pkt_type != PACKET_HOST)
 746                 return 1;
 747
 748         /* If the packet is shorter than 12 bytes, drop packet and return */
 749         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 750                 DCCP_WARN("pskb_may_pull failed\n");
 751                 return 1;
 752         }
 753
 754         dh = dccp_hdr(skb);
 755
 756         /* If P.type is not understood, drop packet and return */
 757         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 758                 DCCP_WARN("invalid packet type\n");
 759                 return 1;
 760         }
 761
 762         /*
 763          * If P.Data Offset is too small for packet type, drop packet and return
 764          */
 765         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 766                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
 767                 return 1;
 768         }
 769         /*
 770          * If P.Data Offset is too too large for packet, drop packet and return
 771          */
 772         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
 773                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
 774                 return 1;
 775         }
 776
 777         /*
 778          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 779          * has short sequence numbers), drop packet and return
 780          */
 781         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 782             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 783                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 784                           dccp_packet_name(dh->dccph_type));
 785                 return 1;
 786         }
 787
 788         /*
 789          * If P.CsCov is too large for the packet size, drop packet and return.
 790          * This must come _before_ checksumming (not as RFC 4340 suggests).
 791          */
 792         cscov = dccp_csum_coverage(skb);
 793         if (cscov > skb->len) {
 794                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 795                           dh->dccph_cscov, skb->len);
 796                 return 1;
 797         }
 798
 799         /* If header checksum is incorrect, drop packet and return.
 800          * (This step is completed in the AF-dependent functions.) */
 801         skb->csum = skb_checksum(skb, 0, cscov, 0);
 802
 803         return 0;
 804 }
 805
 806 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 807
 808 /* this is called when real data arrives */
 809 static int dccp_v4_rcv(struct sk_buff *skb)
 810 {
 811         const struct dccp_hdr *dh;
 812         const struct iphdr *iph;
 813         struct sock *sk;
 814         int min_cov;
 815
 816         /* Step 1: Check header basics */
 817
 818         if (dccp_invalid_packet(skb))
 819                 goto discard_it;
 820
 821         iph = ip_hdr(skb);
 822         /* Step 1: If header checksum is incorrect, drop packet and return */
 823         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 824                 DCCP_WARN("dropped packet with invalid checksum\n");
 825                 goto discard_it;
 826         }
 827
 828         dh = dccp_hdr(skb);
 829
 830         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 831         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 832
 833         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 834                       dccp_packet_name(dh->dccph_type),
 835                       &iph->saddr, ntohs(dh->dccph_sport),
 836                       &iph->daddr, ntohs(dh->dccph_dport),
 837                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 838
 839         if (dccp_packet_without_ack(skb)) {
 840                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 841                 dccp_pr_debug_cat("\n");
 842         } else {
 843                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 844                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 845                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 846         }
 847
 848         /* Step 2:
 849          *      Look up flow ID in table and get corresponding socket */
 850         sk = __inet_lookup_skb(&dccp_hashinfo, skb,
 851                                dh->dccph_sport, dh->dccph_dport);
 852         /*
 853          * Step 2:
 854          *      If no socket ...
 855          */
 856         if (sk == NULL) {
 857                 dccp_pr_debug("failed to look up flow ID in table and "
 858                               "get corresponding socket\n");
 859                 goto no_dccp_socket;
 860         }
 861
 862         /*
 863          * Step 2:
 864          *      ... or S.state == TIMEWAIT,
 865          *              Generate Reset(No Connection) unless P.type == Reset
 866          *              Drop packet and return
 867          */
 868         if (sk->sk_state == DCCP_TIME_WAIT) {
 869                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 870                 inet_twsk_put(inet_twsk(sk));
 871                 goto no_dccp_socket;
 872         }
 873
 874         /*
 875          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 876          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 877          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 878          */
 879         min_cov = dccp_sk(sk)->dccps_pcrlen;
 880         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 881                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 882                               dh->dccph_cscov, min_cov);
 883                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 884                  *         options (Section 11.7) with Drop Code 0, Protocol
 885                  *         Constraints."                                     */
 886                 goto discard_and_relse;
 887         }
 888
 889         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 890                 goto discard_and_relse;
 891         nf_reset(skb);
 892
 893         return sk_receive_skb(sk, skb, 1);
 894
 895 no_dccp_socket:
 896         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 897                 goto discard_it;
 898         /*
 899          * Step 2:
 900          *      If no socket ...
 901          *              Generate Reset(No Connection) unless P.type == Reset
 902          *              Drop packet and return
 903          */
 904         if (dh->dccph_type != DCCP_PKT_RESET) {
 905                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 906                                         DCCP_RESET_CODE_NO_CONNECTION;
 907                 dccp_v4_ctl_send_reset(sk, skb);
 908         }
 909
 910 discard_it:
 911         kfree_skb(skb);
 912         return 0;
 913
 914 discard_and_relse:
 915         sock_put(sk);
 916         goto discard_it;
 917 }
 918
 919 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 920         .queue_xmit        = ip_queue_xmit,
 921         .send_check        = dccp_v4_send_check,
 922         .rebuild_header    = inet_sk_rebuild_header,
 923         .conn_request      = dccp_v4_conn_request,
 924         .syn_recv_sock     = dccp_v4_request_recv_sock,
 925         .net_header_len    = sizeof(struct iphdr),
 926         .setsockopt        = ip_setsockopt,
 927         .getsockopt        = ip_getsockopt,
 928         .addr2sockaddr     = inet_csk_addr2sockaddr,
 929         .sockaddr_len      = sizeof(struct sockaddr_in),
 930         .bind_conflict     = inet_csk_bind_conflict,
 931 #ifdef CONFIG_COMPAT
 932         .compat_setsockopt = compat_ip_setsockopt,
 933         .compat_getsockopt = compat_ip_getsockopt,
 934 #endif
 935 };
 936
 937 static int dccp_v4_init_sock(struct sock *sk)
 938 {
 939         static __u8 dccp_v4_ctl_sock_initialized;
 940         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 941
 942         if (err == 0) {
 943                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 944                         dccp_v4_ctl_sock_initialized = 1;
 945                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 946         }
 947
 948         return err;
 949 }
 950
 951 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 952         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 953 };
 954
 955 static struct proto dccp_v4_prot = {
 956         .name                   = "DCCP",
 957         .owner                  = THIS_MODULE,
 958         .close                  = dccp_close,
 959         .connect                = dccp_v4_connect,
 960         .disconnect             = dccp_disconnect,
 961         .ioctl                  = dccp_ioctl,
 962         .init                   = dccp_v4_init_sock,
 963         .setsockopt             = dccp_setsockopt,
 964         .getsockopt             = dccp_getsockopt,
 965         .sendmsg                = dccp_sendmsg,
 966         .recvmsg                = dccp_recvmsg,
 967         .backlog_rcv            = dccp_v4_do_rcv,
 968         .hash                   = inet_hash,
 969         .unhash                 = inet_unhash,
 970         .accept                 = inet_csk_accept,
 971         .get_port               = inet_csk_get_port,
 972         .shutdown               = dccp_shutdown,
 973         .destroy                = dccp_destroy_sock,
 974         .orphan_count           = &dccp_orphan_count,
 975         .max_header             = MAX_DCCP_HEADER,
 976         .obj_size               = sizeof(struct dccp_sock),
 977         .slab_flags             = SLAB_DESTROY_BY_RCU,
 978         .rsk_prot               = &dccp_request_sock_ops,
 979         .twsk_prot              = &dccp_timewait_sock_ops,
 980         .h.hashinfo             = &dccp_hashinfo,
 981 #ifdef CONFIG_COMPAT
 982         .compat_setsockopt      = compat_dccp_setsockopt,
 983         .compat_getsockopt      = compat_dccp_getsockopt,
 984 #endif
 985 };
 986
 987 static const struct net_protocol dccp_v4_protocol = {
 988         .handler        = dccp_v4_rcv,
 989         .err_handler    = dccp_v4_err,
 990         .no_policy      = 1,
 991         .netns_ok       = 1,
 992         .icmp_strict_tag_validation = 1,
 993 };
 994
 995 static const struct proto_ops inet_dccp_ops = {
 996         .family            = PF_INET,
 997         .owner             = THIS_MODULE,
 998         .release           = inet_release,
 999         .bind              = inet_bind,
1000         .connect           = inet_stream_connect,
1001         .socketpair        = sock_no_socketpair,
1002         .accept            = inet_accept,
1003         .getname           = inet_getname,
1004         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1005         .poll              = dccp_poll,
1006         .ioctl             = inet_ioctl,
1007         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1008         .listen            = inet_dccp_listen,
1009         .shutdown          = inet_shutdown,
1010         .setsockopt        = sock_common_setsockopt,
1011         .getsockopt        = sock_common_getsockopt,
1012         .sendmsg           = inet_sendmsg,
1013         .recvmsg           = sock_common_recvmsg,
1014         .mmap              = sock_no_mmap,
1015         .sendpage          = sock_no_sendpage,
1016 #ifdef CONFIG_COMPAT
1017         .compat_setsockopt = compat_sock_common_setsockopt,
1018         .compat_getsockopt = compat_sock_common_getsockopt,
1019 #endif
1020 };
1021
1022 static struct inet_protosw dccp_v4_protosw = {
1023         .type           = SOCK_DCCP,
1024         .protocol       = IPPROTO_DCCP,
1025         .prot           = &dccp_v4_prot,
1026         .ops            = &inet_dccp_ops,
1027         .no_check       = 0,
1028         .flags          = INET_PROTOSW_ICSK,
1029 };
1030
1031 static int __net_init dccp_v4_init_net(struct net *net)
1032 {
1033         if (dccp_hashinfo.bhash == NULL)
1034                 return -ESOCKTNOSUPPORT;
1035
1036         return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1037                                     SOCK_DCCP, IPPROTO_DCCP, net);
1038 }
1039
1040 static void __net_exit dccp_v4_exit_net(struct net *net)
1041 {
1042         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1043 }
1044
1045 static struct pernet_operations dccp_v4_ops = {
1046         .init   = dccp_v4_init_net,
1047         .exit   = dccp_v4_exit_net,
1048 };
1049
1050 static int __init dccp_v4_init(void)
1051 {
1052         int err = proto_register(&dccp_v4_prot, 1);
1053
1054         if (err != 0)
1055                 goto out;
1056
1057         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1058         if (err != 0)
1059                 goto out_proto_unregister;
1060
1061         inet_register_protosw(&dccp_v4_protosw);
1062
1063         err = register_pernet_subsys(&dccp_v4_ops);
1064         if (err)
1065                 goto out_destroy_ctl_sock;
1066 out:
1067         return err;
1068 out_destroy_ctl_sock:
1069         inet_unregister_protosw(&dccp_v4_protosw);
1070         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1071 out_proto_unregister:
1072         proto_unregister(&dccp_v4_prot);
1073         goto out;
1074 }
1075
1076 static void __exit dccp_v4_exit(void)
1077 {
1078         unregister_pernet_subsys(&dccp_v4_ops);
1079         inet_unregister_protosw(&dccp_v4_protosw);
1080         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1081         proto_unregister(&dccp_v4_prot);
1082 }
1083
1084 module_init(dccp_v4_init);
1085 module_exit(dccp_v4_exit);
1086
1087 /*
1088  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1089  * values directly, Also cover the case where the protocol is not specified,
1090  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1091  */
1092 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1093 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1094 MODULE_LICENSE("GPL");
1095 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1096 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");