net/dccp/ipv4.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  net/dccp/ipv4.c
   4  *
   5  *  An implementation of the DCCP protocol
   6  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   7  */
   8
   9 #include <linux/dccp.h>
  10 #include <linux/icmp.h>
  11 #include <linux/slab.h>
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/random.h>
  15
  16 #include <net/icmp.h>
  17 #include <net/inet_common.h>
  18 #include <net/inet_hashtables.h>
  19 #include <net/inet_sock.h>
  20 #include <net/protocol.h>
  21 #include <net/sock.h>
  22 #include <net/timewait_sock.h>
  23 #include <net/tcp_states.h>
  24 #include <net/xfrm.h>
  25 #include <net/secure_seq.h>
  26
  27 #include "ackvec.h"
  28 #include "ccid.h"
  29 #include "dccp.h"
  30 #include "feat.h"
  31
  32 /*
  33  * The per-net dccp.v4_ctl_sk socket is used for responding to
  34  * the Out-of-the-blue (OOTB) packets. A control sock will be created
  35  * for this socket at the initialization time.
  36  */
  37
  38 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  39 {
  40         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  41         struct inet_sock *inet = inet_sk(sk);
  42         struct dccp_sock *dp = dccp_sk(sk);
  43         __be16 orig_sport, orig_dport;
  44         __be32 daddr, nexthop;
  45         struct flowi4 *fl4;
  46         struct rtable *rt;
  47         int err;
  48         struct ip_options_rcu *inet_opt;
  49
  50         dp->dccps_role = DCCP_ROLE_CLIENT;
  51
  52         if (addr_len < sizeof(struct sockaddr_in))
  53                 return -EINVAL;
  54
  55         if (usin->sin_family != AF_INET)
  56                 return -EAFNOSUPPORT;
  57
  58         nexthop = daddr = usin->sin_addr.s_addr;
  59
  60         inet_opt = rcu_dereference_protected(inet->inet_opt,
  61                                              lockdep_sock_is_held(sk));
  62         if (inet_opt != NULL && inet_opt->opt.srr) {
  63                 if (daddr == 0)
  64                         return -EINVAL;
  65                 nexthop = inet_opt->opt.faddr;
  66         }
  67
  68         orig_sport = inet->inet_sport;
  69         orig_dport = usin->sin_port;
  70         fl4 = &inet->cork.fl.u.ip4;
  71         rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
  72                               RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  73                               IPPROTO_DCCP,
  74                               orig_sport, orig_dport, sk);
  75         if (IS_ERR(rt))
  76                 return PTR_ERR(rt);
  77
  78         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  79                 ip_rt_put(rt);
  80                 return -ENETUNREACH;
  81         }
  82
  83         if (inet_opt == NULL || !inet_opt->opt.srr)
  84                 daddr = fl4->daddr;
  85
  86         if (inet->inet_saddr == 0)
  87                 inet->inet_saddr = fl4->saddr;
  88         sk_rcv_saddr_set(sk, inet->inet_saddr);
  89         inet->inet_dport = usin->sin_port;
  90         sk_daddr_set(sk, daddr);
  91
  92         inet_csk(sk)->icsk_ext_hdr_len = 0;
  93         if (inet_opt)
  94                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
  95         /*
  96          * Socket identity is still unknown (sport may be zero).
  97          * However we set state to DCCP_REQUESTING and not releasing socket
  98          * lock select source port, enter ourselves into the hash tables and
  99          * complete initialization after this.
 100          */
 101         dccp_set_state(sk, DCCP_REQUESTING);
 102         err = inet_hash_connect(&dccp_death_row, sk);
 103         if (err != 0)
 104                 goto failure;
 105
 106         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 107                                inet->inet_sport, inet->inet_dport, sk);
 108         if (IS_ERR(rt)) {
 109                 err = PTR_ERR(rt);
 110                 rt = NULL;
 111                 goto failure;
 112         }
 113         /* OK, now commit destination to socket.  */
 114         sk_setup_caps(sk, &rt->dst);
 115
 116         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 117                                                     inet->inet_daddr,
 118                                                     inet->inet_sport,
 119                                                     inet->inet_dport);
 120         inet->inet_id = prandom_u32();
 121
 122         err = dccp_connect(sk);
 123         rt = NULL;
 124         if (err != 0)
 125                 goto failure;
 126 out:
 127         return err;
 128 failure:
 129         /*
 130          * This unhashes the socket and releases the local port, if necessary.
 131          */
 132         dccp_set_state(sk, DCCP_CLOSED);
 133         ip_rt_put(rt);
 134         sk->sk_route_caps = 0;
 135         inet->inet_dport = 0;
 136         goto out;
 137 }
 138 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 139
 140 /*
 141  * This routine does path mtu discovery as defined in RFC1191.
 142  */
 143 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 144                                           const struct iphdr *iph,
 145                                           u32 mtu)
 146 {
 147         struct dst_entry *dst;
 148         const struct inet_sock *inet = inet_sk(sk);
 149         const struct dccp_sock *dp = dccp_sk(sk);
 150
 151         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 152          * send out by Linux are always < 576bytes so they should go through
 153          * unfragmented).
 154          */
 155         if (sk->sk_state == DCCP_LISTEN)
 156                 return;
 157
 158         dst = inet_csk_update_pmtu(sk, mtu);
 159         if (!dst)
 160                 return;
 161
 162         /* Something is about to be wrong... Remember soft error
 163          * for the case, if this connection will not able to recover.
 164          */
 165         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 166                 sk->sk_err_soft = EMSGSIZE;
 167
 168         mtu = dst_mtu(dst);
 169
 170         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 171             ip_sk_accept_pmtu(sk) &&
 172             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 173                 dccp_sync_mss(sk, mtu);
 174
 175                 /*
 176                  * From RFC 4340, sec. 14.1:
 177                  *
 178                  *      DCCP-Sync packets are the best choice for upward
 179                  *      probing, since DCCP-Sync probes do not risk application
 180                  *      data loss.
 181                  */
 182                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 183         } /* else let the usual retransmit timer handle it */
 184 }
 185
 186 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
 187 {
 188         struct dst_entry *dst = __sk_dst_check(sk, 0);
 189
 190         if (dst)
 191                 dst->ops->redirect(dst, sk, skb);
 192 }
 193
 194 void dccp_req_err(struct sock *sk, u64 seq)
 195         {
 196         struct request_sock *req = inet_reqsk(sk);
 197         struct net *net = sock_net(sk);
 198
 199         /*
 200          * ICMPs are not backlogged, hence we cannot get an established
 201          * socket here.
 202          */
 203         if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
 204                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 205         } else {
 206                 /*
 207                  * Still in RESPOND, just remove it silently.
 208                  * There is no good way to pass the error to the newly
 209                  * created socket, and POSIX does not want network
 210                  * errors returned from accept().
 211                  */
 212                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 213         }
 214         reqsk_put(req);
 215 }
 216 EXPORT_SYMBOL(dccp_req_err);
 217
 218 /*
 219  * This routine is called by the ICMP module when it gets some sort of error
 220  * condition. If err < 0 then the socket should be closed and the error
 221  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 222  * After adjustment header points to the first 8 bytes of the tcp header. We
 223  * need to find the appropriate port.
 224  *
 225  * The locking strategy used here is very "optimistic". When someone else
 226  * accesses the socket the ICMP is just dropped and for some paths there is no
 227  * check at all. A more general error queue to queue errors for later handling
 228  * is probably better.
 229  */
 230 static int dccp_v4_err(struct sk_buff *skb, u32 info)
 231 {
 232         const struct iphdr *iph = (struct iphdr *)skb->data;
 233         const u8 offset = iph->ihl << 2;
 234         const struct dccp_hdr *dh;
 235         struct dccp_sock *dp;
 236         struct inet_sock *inet;
 237         const int type = icmp_hdr(skb)->type;
 238         const int code = icmp_hdr(skb)->code;
 239         struct sock *sk;
 240         __u64 seq;
 241         int err;
 242         struct net *net = dev_net(skb->dev);
 243
 244         /* Only need dccph_dport & dccph_sport which are the first
 245          * 4 bytes in dccp header.
 246          * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
 247          */
 248         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
 249         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
 250         dh = (struct dccp_hdr *)(skb->data + offset);
 251
 252         sk = __inet_lookup_established(net, &dccp_hashinfo,
 253                                        iph->daddr, dh->dccph_dport,
 254                                        iph->saddr, ntohs(dh->dccph_sport),
 255                                        inet_iif(skb), 0);
 256         if (!sk) {
 257                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 258                 return -ENOENT;
 259         }
 260
 261         if (sk->sk_state == DCCP_TIME_WAIT) {
 262                 inet_twsk_put(inet_twsk(sk));
 263                 return 0;
 264         }
 265         seq = dccp_hdr_seq(dh);
 266         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 267                 dccp_req_err(sk, seq);
 268                 return 0;
 269         }
 270
 271         bh_lock_sock(sk);
 272         /* If too many ICMPs get dropped on busy
 273          * servers this needs to be solved differently.
 274          */
 275         if (sock_owned_by_user(sk))
 276                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 277
 278         if (sk->sk_state == DCCP_CLOSED)
 279                 goto out;
 280
 281         dp = dccp_sk(sk);
 282         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 283             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 284                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 285                 goto out;
 286         }
 287
 288         switch (type) {
 289         case ICMP_REDIRECT:
 290                 if (!sock_owned_by_user(sk))
 291                         dccp_do_redirect(skb, sk);
 292                 goto out;
 293         case ICMP_SOURCE_QUENCH:
 294                 /* Just silently ignore these. */
 295                 goto out;
 296         case ICMP_PARAMETERPROB:
 297                 err = EPROTO;
 298                 break;
 299         case ICMP_DEST_UNREACH:
 300                 if (code > NR_ICMP_UNREACH)
 301                         goto out;
 302
 303                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 304                         if (!sock_owned_by_user(sk))
 305                                 dccp_do_pmtu_discovery(sk, iph, info);
 306                         goto out;
 307                 }
 308
 309                 err = icmp_err_convert[code].errno;
 310                 break;
 311         case ICMP_TIME_EXCEEDED:
 312                 err = EHOSTUNREACH;
 313                 break;
 314         default:
 315                 goto out;
 316         }
 317
 318         switch (sk->sk_state) {
 319         case DCCP_REQUESTING:
 320         case DCCP_RESPOND:
 321                 if (!sock_owned_by_user(sk)) {
 322                         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 323                         sk->sk_err = err;
 324
 325                         sk->sk_error_report(sk);
 326
 327                         dccp_done(sk);
 328                 } else
 329                         sk->sk_err_soft = err;
 330                 goto out;
 331         }
 332
 333         /* If we've already connected we will keep trying
 334          * until we time out, or the user gives up.
 335          *
 336          * rfc1122 4.2.3.9 allows to consider as hard errors
 337          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 338          * but it is obsoleted by pmtu discovery).
 339          *
 340          * Note, that in modern internet, where routing is unreliable
 341          * and in each dark corner broken firewalls sit, sending random
 342          * errors ordered by their masters even this two messages finally lose
 343          * their original sense (even Linux sends invalid PORT_UNREACHs)
 344          *
 345          * Now we are in compliance with RFCs.
 346          *                                                      --ANK (980905)
 347          */
 348
 349         inet = inet_sk(sk);
 350         if (!sock_owned_by_user(sk) && inet->recverr) {
 351                 sk->sk_err = err;
 352                 sk->sk_error_report(sk);
 353         } else /* Only an error on timeout */
 354                 sk->sk_err_soft = err;
 355 out:
 356         bh_unlock_sock(sk);
 357         sock_put(sk);
 358         return 0;
 359 }
 360
 361 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 362                                       __be32 src, __be32 dst)
 363 {
 364         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 365 }
 366
 367 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 368 {
 369         const struct inet_sock *inet = inet_sk(sk);
 370         struct dccp_hdr *dh = dccp_hdr(skb);
 371
 372         dccp_csum_outgoing(skb);
 373         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 374                                                  inet->inet_saddr,
 375                                                  inet->inet_daddr);
 376 }
 377 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 378
 379 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 380 {
 381         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 382                                            ip_hdr(skb)->saddr,
 383                                            dccp_hdr(skb)->dccph_dport,
 384                                            dccp_hdr(skb)->dccph_sport);
 385 }
 386
 387 /*
 388  * The three way handshake has completed - we got a valid ACK or DATAACK -
 389  * now create the new socket.
 390  *
 391  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 392  */
 393 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
 394                                        struct sk_buff *skb,
 395                                        struct request_sock *req,
 396                                        struct dst_entry *dst,
 397                                        struct request_sock *req_unhash,
 398                                        bool *own_req)
 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         sk_daddr_set(newsk, ireq->ir_rmt_addr);
 414         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
 415         newinet->inet_saddr     = ireq->ir_loc_addr;
 416         RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
 417         newinet->mc_index  = inet_iif(skb);
 418         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 419         newinet->inet_id   = prandom_u32();
 420
 421         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 422                 goto put_and_exit;
 423
 424         sk_setup_caps(newsk, dst);
 425
 426         dccp_sync_mss(newsk, dst_mtu(dst));
 427
 428         if (__inet_inherit_port(sk, newsk) < 0)
 429                 goto put_and_exit;
 430         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
 431         if (*own_req)
 432                 ireq->ireq_opt = NULL;
 433         else
 434                 newinet->inet_opt = NULL;
 435         return newsk;
 436
 437 exit_overflow:
 438         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 439 exit_nonewsk:
 440         dst_release(dst);
 441 exit:
 442         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
 443         return NULL;
 444 put_and_exit:
 445         newinet->inet_opt = NULL;
 446         inet_csk_prepare_forced_close(newsk);
 447         dccp_done(newsk);
 448         goto exit;
 449 }
 450 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 451
 452 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 453                                            struct sk_buff *skb)
 454 {
 455         struct rtable *rt;
 456         const struct iphdr *iph = ip_hdr(skb);
 457         struct flowi4 fl4 = {
 458                 .flowi4_oif = inet_iif(skb),
 459                 .daddr = iph->saddr,
 460                 .saddr = iph->daddr,
 461                 .flowi4_tos = RT_CONN_FLAGS(sk),
 462                 .flowi4_proto = sk->sk_protocol,
 463                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 464                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 465         };
 466
 467         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 468         rt = ip_route_output_flow(net, &fl4, sk);
 469         if (IS_ERR(rt)) {
 470                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 471                 return NULL;
 472         }
 473
 474         return &rt->dst;
 475 }
 476
 477 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
 478 {
 479         int err = -1;
 480         struct sk_buff *skb;
 481         struct dst_entry *dst;
 482         struct flowi4 fl4;
 483
 484         dst = inet_csk_route_req(sk, &fl4, req);
 485         if (dst == NULL)
 486                 goto out;
 487
 488         skb = dccp_make_response(sk, dst, req);
 489         if (skb != NULL) {
 490                 const struct inet_request_sock *ireq = inet_rsk(req);
 491                 struct dccp_hdr *dh = dccp_hdr(skb);
 492
 493                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 494                                                               ireq->ir_rmt_addr);
 495                 rcu_read_lock();
 496                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 497                                             ireq->ir_rmt_addr,
 498                                             rcu_dereference(ireq->ireq_opt));
 499                 rcu_read_unlock();
 500                 err = net_xmit_eval(err);
 501         }
 502
 503 out:
 504         dst_release(dst);
 505         return err;
 506 }
 507
 508 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 509 {
 510         int err;
 511         const struct iphdr *rxiph;
 512         struct sk_buff *skb;
 513         struct dst_entry *dst;
 514         struct net *net = dev_net(skb_dst(rxskb)->dev);
 515         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
 516
 517         /* Never send a reset in response to a reset. */
 518         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 519                 return;
 520
 521         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 522                 return;
 523
 524         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 525         if (dst == NULL)
 526                 return;
 527
 528         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 529         if (skb == NULL)
 530                 goto out;
 531
 532         rxiph = ip_hdr(rxskb);
 533         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 534                                                                  rxiph->daddr);
 535         skb_dst_set(skb, dst_clone(dst));
 536
 537         local_bh_disable();
 538         bh_lock_sock(ctl_sk);
 539         err = ip_build_and_send_pkt(skb, ctl_sk,
 540                                     rxiph->daddr, rxiph->saddr, NULL);
 541         bh_unlock_sock(ctl_sk);
 542
 543         if (net_xmit_eval(err) == 0) {
 544                 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 545                 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 546         }
 547         local_bh_enable();
 548 out:
 549         dst_release(dst);
 550 }
 551
 552 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 553 {
 554         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 555         kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
 556 }
 557
 558 void dccp_syn_ack_timeout(const struct request_sock *req)
 559 {
 560 }
 561 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 562
 563 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 564         .family         = PF_INET,
 565         .obj_size       = sizeof(struct dccp_request_sock),
 566         .rtx_syn_ack    = dccp_v4_send_response,
 567         .send_ack       = dccp_reqsk_send_ack,
 568         .destructor     = dccp_v4_reqsk_destructor,
 569         .send_reset     = dccp_v4_ctl_send_reset,
 570         .syn_ack_timeout = dccp_syn_ack_timeout,
 571 };
 572
 573 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 574 {
 575         struct inet_request_sock *ireq;
 576         struct request_sock *req;
 577         struct dccp_request_sock *dreq;
 578         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 579         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 580
 581         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 582         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 583                 return 0;       /* discard, don't send a reset here */
 584
 585         if (dccp_bad_service_code(sk, service)) {
 586                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 587                 goto drop;
 588         }
 589         /*
 590          * TW buckets are converted to open requests without
 591          * limitations, they conserve resources and peer is
 592          * evidently real one.
 593          */
 594         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 595         if (inet_csk_reqsk_queue_is_full(sk))
 596                 goto drop;
 597
 598         if (sk_acceptq_is_full(sk))
 599                 goto drop;
 600
 601         req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
 602         if (req == NULL)
 603                 goto drop;
 604
 605         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 606                 goto drop_and_free;
 607
 608         dreq = dccp_rsk(req);
 609         if (dccp_parse_options(sk, dreq, skb))
 610                 goto drop_and_free;
 611
 612         if (security_inet_conn_request(sk, skb, req))
 613                 goto drop_and_free;
 614
 615         ireq = inet_rsk(req);
 616         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
 617         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 618         ireq->ir_mark = inet_request_mark(sk, skb);
 619         ireq->ireq_family = AF_INET;
 620         ireq->ir_iif = sk->sk_bound_dev_if;
 621
 622         /*
 623          * Step 3: Process LISTEN state
 624          *
 625          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 626          *
 627          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 628          */
 629         dreq->dreq_isr     = dcb->dccpd_seq;
 630         dreq->dreq_gsr     = dreq->dreq_isr;
 631         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 632         dreq->dreq_gss     = dreq->dreq_iss;
 633         dreq->dreq_service = service;
 634
 635         if (dccp_v4_send_response(sk, req))
 636                 goto drop_and_free;
 637
 638         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 639         reqsk_put(req);
 640         return 0;
 641
 642 drop_and_free:
 643         reqsk_free(req);
 644 drop:
 645         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 646         return -1;
 647 }
 648 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 649
 650 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 651 {
 652         struct dccp_hdr *dh = dccp_hdr(skb);
 653
 654         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 655                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 656                         goto reset;
 657                 return 0;
 658         }
 659
 660         /*
 661          *  Step 3: Process LISTEN state
 662          *       If P.type == Request or P contains a valid Init Cookie option,
 663          *            (* Must scan the packet's options to check for Init
 664          *               Cookies.  Only Init Cookies are processed here,
 665          *               however; other options are processed in Step 8.  This
 666          *               scan need only be performed if the endpoint uses Init
 667          *               Cookies *)
 668          *            (* Generate a new socket and switch to that socket *)
 669          *            Set S := new socket for this port pair
 670          *            S.state = RESPOND
 671          *            Choose S.ISS (initial seqno) or set from Init Cookies
 672          *            Initialize S.GAR := S.ISS
 673          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 674          *            Continue with S.state == RESPOND
 675          *            (* A Response packet will be generated in Step 11 *)
 676          *       Otherwise,
 677          *            Generate Reset(No Connection) unless P.type == Reset
 678          *            Drop packet and return
 679          *
 680          * NOTE: the check for the packet types is done in
 681          *       dccp_rcv_state_process
 682          */
 683
 684         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 685                 goto reset;
 686         return 0;
 687
 688 reset:
 689         dccp_v4_ctl_send_reset(sk, skb);
 690         kfree_skb(skb);
 691         return 0;
 692 }
 693 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 694
 695 /**
 696  *      dccp_invalid_packet  -  check for malformed packets
 697  *      @skb: Packet to validate
 698  *
 699  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 700  *      Packets that fail these checks are ignored and do not receive Resets.
 701  */
 702 int dccp_invalid_packet(struct sk_buff *skb)
 703 {
 704         const struct dccp_hdr *dh;
 705         unsigned int cscov;
 706         u8 dccph_doff;
 707
 708         if (skb->pkt_type != PACKET_HOST)
 709                 return 1;
 710
 711         /* If the packet is shorter than 12 bytes, drop packet and return */
 712         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 713                 DCCP_WARN("pskb_may_pull failed\n");
 714                 return 1;
 715         }
 716
 717         dh = dccp_hdr(skb);
 718
 719         /* If P.type is not understood, drop packet and return */
 720         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 721                 DCCP_WARN("invalid packet type\n");
 722                 return 1;
 723         }
 724
 725         /*
 726          * If P.Data Offset is too small for packet type, drop packet and return
 727          */
 728         dccph_doff = dh->dccph_doff;
 729         if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 730                 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
 731                 return 1;
 732         }
 733         /*
 734          * If P.Data Offset is too too large for packet, drop packet and return
 735          */
 736         if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
 737                 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
 738                 return 1;
 739         }
 740         dh = dccp_hdr(skb);
 741         /*
 742          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 743          * has short sequence numbers), drop packet and return
 744          */
 745         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 746             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 747                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 748                           dccp_packet_name(dh->dccph_type));
 749                 return 1;
 750         }
 751
 752         /*
 753          * If P.CsCov is too large for the packet size, drop packet and return.
 754          * This must come _before_ checksumming (not as RFC 4340 suggests).
 755          */
 756         cscov = dccp_csum_coverage(skb);
 757         if (cscov > skb->len) {
 758                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 759                           dh->dccph_cscov, skb->len);
 760                 return 1;
 761         }
 762
 763         /* If header checksum is incorrect, drop packet and return.
 764          * (This step is completed in the AF-dependent functions.) */
 765         skb->csum = skb_checksum(skb, 0, cscov, 0);
 766
 767         return 0;
 768 }
 769 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 770
 771 /* this is called when real data arrives */
 772 static int dccp_v4_rcv(struct sk_buff *skb)
 773 {
 774         const struct dccp_hdr *dh;
 775         const struct iphdr *iph;
 776         bool refcounted;
 777         struct sock *sk;
 778         int min_cov;
 779
 780         /* Step 1: Check header basics */
 781
 782         if (dccp_invalid_packet(skb))
 783                 goto discard_it;
 784
 785         iph = ip_hdr(skb);
 786         /* Step 1: If header checksum is incorrect, drop packet and return */
 787         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 788                 DCCP_WARN("dropped packet with invalid checksum\n");
 789                 goto discard_it;
 790         }
 791
 792         dh = dccp_hdr(skb);
 793
 794         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 795         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 796
 797         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 798                       dccp_packet_name(dh->dccph_type),
 799                       &iph->saddr, ntohs(dh->dccph_sport),
 800                       &iph->daddr, ntohs(dh->dccph_dport),
 801                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 802
 803         if (dccp_packet_without_ack(skb)) {
 804                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 805                 dccp_pr_debug_cat("\n");
 806         } else {
 807                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 808                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 809                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 810         }
 811
 812 lookup:
 813         sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
 814                                dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
 815         if (!sk) {
 816                 dccp_pr_debug("failed to look up flow ID in table and "
 817                               "get corresponding socket\n");
 818                 goto no_dccp_socket;
 819         }
 820
 821         /*
 822          * Step 2:
 823          *      ... or S.state == TIMEWAIT,
 824          *              Generate Reset(No Connection) unless P.type == Reset
 825          *              Drop packet and return
 826          */
 827         if (sk->sk_state == DCCP_TIME_WAIT) {
 828                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 829                 inet_twsk_put(inet_twsk(sk));
 830                 goto no_dccp_socket;
 831         }
 832
 833         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 834                 struct request_sock *req = inet_reqsk(sk);
 835                 struct sock *nsk;
 836
 837                 sk = req->rsk_listener;
 838                 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
 839                         inet_csk_reqsk_queue_drop_and_put(sk, req);
 840                         goto lookup;
 841                 }
 842                 sock_hold(sk);
 843                 refcounted = true;
 844                 nsk = dccp_check_req(sk, skb, req);
 845                 if (!nsk) {
 846                         reqsk_put(req);
 847                         goto discard_and_relse;
 848                 }
 849                 if (nsk == sk) {
 850                         reqsk_put(req);
 851                 } else if (dccp_child_process(sk, nsk, skb)) {
 852                         dccp_v4_ctl_send_reset(sk, skb);
 853                         goto discard_and_relse;
 854                 } else {
 855                         sock_put(sk);
 856                         return 0;
 857                 }
 858         }
 859         /*
 860          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 861          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 862          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 863          */
 864         min_cov = dccp_sk(sk)->dccps_pcrlen;
 865         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 866                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 867                               dh->dccph_cscov, min_cov);
 868                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 869                  *         options (Section 11.7) with Drop Code 0, Protocol
 870                  *         Constraints."                                     */
 871                 goto discard_and_relse;
 872         }
 873
 874         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 875                 goto discard_and_relse;
 876         nf_reset_ct(skb);
 877
 878         return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
 879
 880 no_dccp_socket:
 881         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 882                 goto discard_it;
 883         /*
 884          * Step 2:
 885          *      If no socket ...
 886          *              Generate Reset(No Connection) unless P.type == Reset
 887          *              Drop packet and return
 888          */
 889         if (dh->dccph_type != DCCP_PKT_RESET) {
 890                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 891                                         DCCP_RESET_CODE_NO_CONNECTION;
 892                 dccp_v4_ctl_send_reset(sk, skb);
 893         }
 894
 895 discard_it:
 896         kfree_skb(skb);
 897         return 0;
 898
 899 discard_and_relse:
 900         if (refcounted)
 901                 sock_put(sk);
 902         goto discard_it;
 903 }
 904
 905 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 906         .queue_xmit        = ip_queue_xmit,
 907         .send_check        = dccp_v4_send_check,
 908         .rebuild_header    = inet_sk_rebuild_header,
 909         .conn_request      = dccp_v4_conn_request,
 910         .syn_recv_sock     = dccp_v4_request_recv_sock,
 911         .net_header_len    = sizeof(struct iphdr),
 912         .setsockopt        = ip_setsockopt,
 913         .getsockopt        = ip_getsockopt,
 914         .addr2sockaddr     = inet_csk_addr2sockaddr,
 915         .sockaddr_len      = sizeof(struct sockaddr_in),
 916 };
 917
 918 static int dccp_v4_init_sock(struct sock *sk)
 919 {
 920         static __u8 dccp_v4_ctl_sock_initialized;
 921         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 922
 923         if (err == 0) {
 924                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 925                         dccp_v4_ctl_sock_initialized = 1;
 926                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 927         }
 928
 929         return err;
 930 }
 931
 932 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 933         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 934 };
 935
 936 static struct proto dccp_v4_prot = {
 937         .name                   = "DCCP",
 938         .owner                  = THIS_MODULE,
 939         .close                  = dccp_close,
 940         .connect                = dccp_v4_connect,
 941         .disconnect             = dccp_disconnect,
 942         .ioctl                  = dccp_ioctl,
 943         .init                   = dccp_v4_init_sock,
 944         .setsockopt             = dccp_setsockopt,
 945         .getsockopt             = dccp_getsockopt,
 946         .sendmsg                = dccp_sendmsg,
 947         .recvmsg                = dccp_recvmsg,
 948         .backlog_rcv            = dccp_v4_do_rcv,
 949         .hash                   = inet_hash,
 950         .unhash                 = inet_unhash,
 951         .accept                 = inet_csk_accept,
 952         .get_port               = inet_csk_get_port,
 953         .shutdown               = dccp_shutdown,
 954         .destroy                = dccp_destroy_sock,
 955         .orphan_count           = &dccp_orphan_count,
 956         .max_header             = MAX_DCCP_HEADER,
 957         .obj_size               = sizeof(struct dccp_sock),
 958         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
 959         .rsk_prot               = &dccp_request_sock_ops,
 960         .twsk_prot              = &dccp_timewait_sock_ops,
 961         .h.hashinfo             = &dccp_hashinfo,
 962 };
 963
 964 static const struct net_protocol dccp_v4_protocol = {
 965         .handler        = dccp_v4_rcv,
 966         .err_handler    = dccp_v4_err,
 967         .no_policy      = 1,
 968         .netns_ok       = 1,
 969         .icmp_strict_tag_validation = 1,
 970 };
 971
 972 static const struct proto_ops inet_dccp_ops = {
 973         .family            = PF_INET,
 974         .owner             = THIS_MODULE,
 975         .release           = inet_release,
 976         .bind              = inet_bind,
 977         .connect           = inet_stream_connect,
 978         .socketpair        = sock_no_socketpair,
 979         .accept            = inet_accept,
 980         .getname           = inet_getname,
 981         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 982         .poll              = dccp_poll,
 983         .ioctl             = inet_ioctl,
 984         .gettstamp         = sock_gettstamp,
 985         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 986         .listen            = inet_dccp_listen,
 987         .shutdown          = inet_shutdown,
 988         .setsockopt        = sock_common_setsockopt,
 989         .getsockopt        = sock_common_getsockopt,
 990         .sendmsg           = inet_sendmsg,
 991         .recvmsg           = sock_common_recvmsg,
 992         .mmap              = sock_no_mmap,
 993         .sendpage          = sock_no_sendpage,
 994 };
 995
 996 static struct inet_protosw dccp_v4_protosw = {
 997         .type           = SOCK_DCCP,
 998         .protocol       = IPPROTO_DCCP,
 999         .prot           = &dccp_v4_prot,
1000         .ops            = &inet_dccp_ops,
1001         .flags          = INET_PROTOSW_ICSK,
1002 };
1003
1004 static int __net_init dccp_v4_init_net(struct net *net)
1005 {
1006         if (dccp_hashinfo.bhash == NULL)
1007                 return -ESOCKTNOSUPPORT;
1008
1009         return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1010                                     SOCK_DCCP, IPPROTO_DCCP, net);
1011 }
1012
1013 static void __net_exit dccp_v4_exit_net(struct net *net)
1014 {
1015         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1016 }
1017
1018 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1019 {
1020         inet_twsk_purge(&dccp_hashinfo, AF_INET);
1021 }
1022
1023 static struct pernet_operations dccp_v4_ops = {
1024         .init   = dccp_v4_init_net,
1025         .exit   = dccp_v4_exit_net,
1026         .exit_batch = dccp_v4_exit_batch,
1027 };
1028
1029 static int __init dccp_v4_init(void)
1030 {
1031         int err = proto_register(&dccp_v4_prot, 1);
1032
1033         if (err)
1034                 goto out;
1035
1036         inet_register_protosw(&dccp_v4_protosw);
1037
1038         err = register_pernet_subsys(&dccp_v4_ops);
1039         if (err)
1040                 goto out_destroy_ctl_sock;
1041
1042         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1043         if (err)
1044                 goto out_proto_unregister;
1045
1046 out:
1047         return err;
1048 out_proto_unregister:
1049         unregister_pernet_subsys(&dccp_v4_ops);
1050 out_destroy_ctl_sock:
1051         inet_unregister_protosw(&dccp_v4_protosw);
1052         proto_unregister(&dccp_v4_prot);
1053         goto out;
1054 }
1055
1056 static void __exit dccp_v4_exit(void)
1057 {
1058         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1059         unregister_pernet_subsys(&dccp_v4_ops);
1060         inet_unregister_protosw(&dccp_v4_protosw);
1061         proto_unregister(&dccp_v4_prot);
1062 }
1063
1064 module_init(dccp_v4_init);
1065 module_exit(dccp_v4_exit);
1066
1067 /*
1068  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1069  * values directly, Also cover the case where the protocol is not specified,
1070  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1071  */
1072 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1073 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1074 MODULE_LICENSE("GPL");
1075 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1076 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");