net/dccp/ipv4.c

   1 /*
   2  *  net/dccp/ipv4.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <[email protected]>
   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                                              lockdep_sock_is_held(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         sk_rcv_saddr_set(sk, inet->inet_saddr);
  93         inet->inet_dport = usin->sin_port;
  94         sk_daddr_set(sk, daddr);
  95
  96         inet_csk(sk)->icsk_ext_hdr_len = 0;
  97         if (inet_opt)
  98                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
  99         /*
 100          * Socket identity is still unknown (sport may be zero).
 101          * However we set state to DCCP_REQUESTING and not releasing socket
 102          * lock select source port, enter ourselves into the hash tables and
 103          * complete initialization after this.
 104          */
 105         dccp_set_state(sk, DCCP_REQUESTING);
 106         err = inet_hash_connect(&dccp_death_row, sk);
 107         if (err != 0)
 108                 goto failure;
 109
 110         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 111                                inet->inet_sport, inet->inet_dport, sk);
 112         if (IS_ERR(rt)) {
 113                 err = PTR_ERR(rt);
 114                 rt = NULL;
 115                 goto failure;
 116         }
 117         /* OK, now commit destination to socket.  */
 118         sk_setup_caps(sk, &rt->dst);
 119
 120         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 121                                                     inet->inet_daddr,
 122                                                     inet->inet_sport,
 123                                                     inet->inet_dport);
 124         inet->inet_id = dp->dccps_iss ^ jiffies;
 125
 126         err = dccp_connect(sk);
 127         rt = NULL;
 128         if (err != 0)
 129                 goto failure;
 130 out:
 131         return err;
 132 failure:
 133         /*
 134          * This unhashes the socket and releases the local port, if necessary.
 135          */
 136         dccp_set_state(sk, DCCP_CLOSED);
 137         ip_rt_put(rt);
 138         sk->sk_route_caps = 0;
 139         inet->inet_dport = 0;
 140         goto out;
 141 }
 142 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 143
 144 /*
 145  * This routine does path mtu discovery as defined in RFC1191.
 146  */
 147 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 148                                           const struct iphdr *iph,
 149                                           u32 mtu)
 150 {
 151         struct dst_entry *dst;
 152         const struct inet_sock *inet = inet_sk(sk);
 153         const struct dccp_sock *dp = dccp_sk(sk);
 154
 155         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 156          * send out by Linux are always < 576bytes so they should go through
 157          * unfragmented).
 158          */
 159         if (sk->sk_state == DCCP_LISTEN)
 160                 return;
 161
 162         dst = inet_csk_update_pmtu(sk, mtu);
 163         if (!dst)
 164                 return;
 165
 166         /* Something is about to be wrong... Remember soft error
 167          * for the case, if this connection will not able to recover.
 168          */
 169         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 170                 sk->sk_err_soft = EMSGSIZE;
 171
 172         mtu = dst_mtu(dst);
 173
 174         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 175             ip_sk_accept_pmtu(sk) &&
 176             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 177                 dccp_sync_mss(sk, mtu);
 178
 179                 /*
 180                  * From RFC 4340, sec. 14.1:
 181                  *
 182                  *      DCCP-Sync packets are the best choice for upward
 183                  *      probing, since DCCP-Sync probes do not risk application
 184                  *      data loss.
 185                  */
 186                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 187         } /* else let the usual retransmit timer handle it */
 188 }
 189
 190 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
 191 {
 192         struct dst_entry *dst = __sk_dst_check(sk, 0);
 193
 194         if (dst)
 195                 dst->ops->redirect(dst, sk, skb);
 196 }
 197
 198 void dccp_req_err(struct sock *sk, u64 seq)
 199         {
 200         struct request_sock *req = inet_reqsk(sk);
 201         struct net *net = sock_net(sk);
 202
 203         /*
 204          * ICMPs are not backlogged, hence we cannot get an established
 205          * socket here.
 206          */
 207         if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
 208                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 209         } else {
 210                 /*
 211                  * Still in RESPOND, just remove it silently.
 212                  * There is no good way to pass the error to the newly
 213                  * created socket, and POSIX does not want network
 214                  * errors returned from accept().
 215                  */
 216                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 217         }
 218         reqsk_put(req);
 219 }
 220 EXPORT_SYMBOL(dccp_req_err);
 221
 222 /*
 223  * This routine is called by the ICMP module when it gets some sort of error
 224  * condition. If err < 0 then the socket should be closed and the error
 225  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 226  * After adjustment header points to the first 8 bytes of the tcp header. We
 227  * need to find the appropriate port.
 228  *
 229  * The locking strategy used here is very "optimistic". When someone else
 230  * accesses the socket the ICMP is just dropped and for some paths there is no
 231  * check at all. A more general error queue to queue errors for later handling
 232  * is probably better.
 233  */
 234 static int dccp_v4_err(struct sk_buff *skb, u32 info)
 235 {
 236         const struct iphdr *iph = (struct iphdr *)skb->data;
 237         const u8 offset = iph->ihl << 2;
 238         const struct dccp_hdr *dh;
 239         struct dccp_sock *dp;
 240         struct inet_sock *inet;
 241         const int type = icmp_hdr(skb)->type;
 242         const int code = icmp_hdr(skb)->code;
 243         struct sock *sk;
 244         __u64 seq;
 245         int err;
 246         struct net *net = dev_net(skb->dev);
 247
 248         /* Only need dccph_dport & dccph_sport which are the first
 249          * 4 bytes in dccp header.
 250          * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
 251          */
 252         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
 253         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
 254         dh = (struct dccp_hdr *)(skb->data + offset);
 255
 256         sk = __inet_lookup_established(net, &dccp_hashinfo,
 257                                        iph->daddr, dh->dccph_dport,
 258                                        iph->saddr, ntohs(dh->dccph_sport),
 259                                        inet_iif(skb), 0);
 260         if (!sk) {
 261                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 262                 return -ENOENT;
 263         }
 264
 265         if (sk->sk_state == DCCP_TIME_WAIT) {
 266                 inet_twsk_put(inet_twsk(sk));
 267                 return 0;
 268         }
 269         seq = dccp_hdr_seq(dh);
 270         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 271                 dccp_req_err(sk, seq);
 272                 return 0;
 273         }
 274
 275         bh_lock_sock(sk);
 276         /* If too many ICMPs get dropped on busy
 277          * servers this needs to be solved differently.
 278          */
 279         if (sock_owned_by_user(sk))
 280                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 281
 282         if (sk->sk_state == DCCP_CLOSED)
 283                 goto out;
 284
 285         dp = dccp_sk(sk);
 286         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 287             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 288                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 289                 goto out;
 290         }
 291
 292         switch (type) {
 293         case ICMP_REDIRECT:
 294                 if (!sock_owned_by_user(sk))
 295                         dccp_do_redirect(skb, sk);
 296                 goto out;
 297         case ICMP_SOURCE_QUENCH:
 298                 /* Just silently ignore these. */
 299                 goto out;
 300         case ICMP_PARAMETERPROB:
 301                 err = EPROTO;
 302                 break;
 303         case ICMP_DEST_UNREACH:
 304                 if (code > NR_ICMP_UNREACH)
 305                         goto out;
 306
 307                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 308                         if (!sock_owned_by_user(sk))
 309                                 dccp_do_pmtu_discovery(sk, iph, info);
 310                         goto out;
 311                 }
 312
 313                 err = icmp_err_convert[code].errno;
 314                 break;
 315         case ICMP_TIME_EXCEEDED:
 316                 err = EHOSTUNREACH;
 317                 break;
 318         default:
 319                 goto out;
 320         }
 321
 322         switch (sk->sk_state) {
 323         case DCCP_REQUESTING:
 324         case DCCP_RESPOND:
 325                 if (!sock_owned_by_user(sk)) {
 326                         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 327                         sk->sk_err = err;
 328
 329                         sk->sk_error_report(sk);
 330
 331                         dccp_done(sk);
 332                 } else
 333                         sk->sk_err_soft = err;
 334                 goto out;
 335         }
 336
 337         /* If we've already connected we will keep trying
 338          * until we time out, or the user gives up.
 339          *
 340          * rfc1122 4.2.3.9 allows to consider as hard errors
 341          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 342          * but it is obsoleted by pmtu discovery).
 343          *
 344          * Note, that in modern internet, where routing is unreliable
 345          * and in each dark corner broken firewalls sit, sending random
 346          * errors ordered by their masters even this two messages finally lose
 347          * their original sense (even Linux sends invalid PORT_UNREACHs)
 348          *
 349          * Now we are in compliance with RFCs.
 350          *                                                      --ANK (980905)
 351          */
 352
 353         inet = inet_sk(sk);
 354         if (!sock_owned_by_user(sk) && inet->recverr) {
 355                 sk->sk_err = err;
 356                 sk->sk_error_report(sk);
 357         } else /* Only an error on timeout */
 358                 sk->sk_err_soft = err;
 359 out:
 360         bh_unlock_sock(sk);
 361         sock_put(sk);
 362         return 0;
 363 }
 364
 365 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 366                                       __be32 src, __be32 dst)
 367 {
 368         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 369 }
 370
 371 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 372 {
 373         const struct inet_sock *inet = inet_sk(sk);
 374         struct dccp_hdr *dh = dccp_hdr(skb);
 375
 376         dccp_csum_outgoing(skb);
 377         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 378                                                  inet->inet_saddr,
 379                                                  inet->inet_daddr);
 380 }
 381 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 382
 383 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 384 {
 385         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 386                                            ip_hdr(skb)->saddr,
 387                                            dccp_hdr(skb)->dccph_dport,
 388                                            dccp_hdr(skb)->dccph_sport);
 389 }
 390
 391 /*
 392  * The three way handshake has completed - we got a valid ACK or DATAACK -
 393  * now create the new socket.
 394  *
 395  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 396  */
 397 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
 398                                        struct sk_buff *skb,
 399                                        struct request_sock *req,
 400                                        struct dst_entry *dst,
 401                                        struct request_sock *req_unhash,
 402                                        bool *own_req)
 403 {
 404         struct inet_request_sock *ireq;
 405         struct inet_sock *newinet;
 406         struct sock *newsk;
 407
 408         if (sk_acceptq_is_full(sk))
 409                 goto exit_overflow;
 410
 411         newsk = dccp_create_openreq_child(sk, req, skb);
 412         if (newsk == NULL)
 413                 goto exit_nonewsk;
 414
 415         newinet            = inet_sk(newsk);
 416         ireq               = inet_rsk(req);
 417         sk_daddr_set(newsk, ireq->ir_rmt_addr);
 418         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
 419         newinet->inet_saddr     = ireq->ir_loc_addr;
 420         RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
 421         newinet->mc_index  = inet_iif(skb);
 422         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 423         newinet->inet_id   = jiffies;
 424
 425         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 426                 goto put_and_exit;
 427
 428         sk_setup_caps(newsk, dst);
 429
 430         dccp_sync_mss(newsk, dst_mtu(dst));
 431
 432         if (__inet_inherit_port(sk, newsk) < 0)
 433                 goto put_and_exit;
 434         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
 435         if (*own_req)
 436                 ireq->ireq_opt = NULL;
 437         else
 438                 newinet->inet_opt = NULL;
 439         return newsk;
 440
 441 exit_overflow:
 442         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 443 exit_nonewsk:
 444         dst_release(dst);
 445 exit:
 446         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
 447         return NULL;
 448 put_and_exit:
 449         newinet->inet_opt = NULL;
 450         inet_csk_prepare_forced_close(newsk);
 451         dccp_done(newsk);
 452         goto exit;
 453 }
 454 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 455
 456 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 457                                            struct sk_buff *skb)
 458 {
 459         struct rtable *rt;
 460         const struct iphdr *iph = ip_hdr(skb);
 461         struct flowi4 fl4 = {
 462                 .flowi4_oif = inet_iif(skb),
 463                 .daddr = iph->saddr,
 464                 .saddr = iph->daddr,
 465                 .flowi4_tos = RT_CONN_FLAGS(sk),
 466                 .flowi4_proto = sk->sk_protocol,
 467                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 468                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 469         };
 470
 471         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 472         rt = ip_route_output_flow(net, &fl4, sk);
 473         if (IS_ERR(rt)) {
 474                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 475                 return NULL;
 476         }
 477
 478         return &rt->dst;
 479 }
 480
 481 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
 482 {
 483         int err = -1;
 484         struct sk_buff *skb;
 485         struct dst_entry *dst;
 486         struct flowi4 fl4;
 487
 488         dst = inet_csk_route_req(sk, &fl4, req);
 489         if (dst == NULL)
 490                 goto out;
 491
 492         skb = dccp_make_response(sk, dst, req);
 493         if (skb != NULL) {
 494                 const struct inet_request_sock *ireq = inet_rsk(req);
 495                 struct dccp_hdr *dh = dccp_hdr(skb);
 496
 497                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 498                                                               ireq->ir_rmt_addr);
 499                 rcu_read_lock();
 500                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 501                                             ireq->ir_rmt_addr,
 502                                             rcu_dereference(ireq->ireq_opt));
 503                 rcu_read_unlock();
 504                 err = net_xmit_eval(err);
 505         }
 506
 507 out:
 508         dst_release(dst);
 509         return err;
 510 }
 511
 512 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 513 {
 514         int err;
 515         const struct iphdr *rxiph;
 516         struct sk_buff *skb;
 517         struct dst_entry *dst;
 518         struct net *net = dev_net(skb_dst(rxskb)->dev);
 519         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
 520
 521         /* Never send a reset in response to a reset. */
 522         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 523                 return;
 524
 525         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 526                 return;
 527
 528         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 529         if (dst == NULL)
 530                 return;
 531
 532         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 533         if (skb == NULL)
 534                 goto out;
 535
 536         rxiph = ip_hdr(rxskb);
 537         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 538                                                                  rxiph->daddr);
 539         skb_dst_set(skb, dst_clone(dst));
 540
 541         local_bh_disable();
 542         bh_lock_sock(ctl_sk);
 543         err = ip_build_and_send_pkt(skb, ctl_sk,
 544                                     rxiph->daddr, rxiph->saddr, NULL);
 545         bh_unlock_sock(ctl_sk);
 546
 547         if (net_xmit_eval(err) == 0) {
 548                 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 549                 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 550         }
 551         local_bh_enable();
 552 out:
 553         dst_release(dst);
 554 }
 555
 556 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 557 {
 558         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 559         kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
 560 }
 561
 562 void dccp_syn_ack_timeout(const struct request_sock *req)
 563 {
 564 }
 565 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 566
 567 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 568         .family         = PF_INET,
 569         .obj_size       = sizeof(struct dccp_request_sock),
 570         .rtx_syn_ack    = dccp_v4_send_response,
 571         .send_ack       = dccp_reqsk_send_ack,
 572         .destructor     = dccp_v4_reqsk_destructor,
 573         .send_reset     = dccp_v4_ctl_send_reset,
 574         .syn_ack_timeout = dccp_syn_ack_timeout,
 575 };
 576
 577 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 578 {
 579         struct inet_request_sock *ireq;
 580         struct request_sock *req;
 581         struct dccp_request_sock *dreq;
 582         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 583         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 584
 585         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 586         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 587                 return 0;       /* discard, don't send a reset here */
 588
 589         if (dccp_bad_service_code(sk, service)) {
 590                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 591                 goto drop;
 592         }
 593         /*
 594          * TW buckets are converted to open requests without
 595          * limitations, they conserve resources and peer is
 596          * evidently real one.
 597          */
 598         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 599         if (inet_csk_reqsk_queue_is_full(sk))
 600                 goto drop;
 601
 602         if (sk_acceptq_is_full(sk))
 603                 goto drop;
 604
 605         req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
 606         if (req == NULL)
 607                 goto drop;
 608
 609         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 610                 goto drop_and_free;
 611
 612         dreq = dccp_rsk(req);
 613         if (dccp_parse_options(sk, dreq, skb))
 614                 goto drop_and_free;
 615
 616         if (security_inet_conn_request(sk, skb, req))
 617                 goto drop_and_free;
 618
 619         ireq = inet_rsk(req);
 620         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
 621         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 622         ireq->ir_mark = inet_request_mark(sk, skb);
 623         ireq->ireq_family = AF_INET;
 624         ireq->ir_iif = sk->sk_bound_dev_if;
 625
 626         /*
 627          * Step 3: Process LISTEN state
 628          *
 629          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 630          *
 631          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 632          */
 633         dreq->dreq_isr     = dcb->dccpd_seq;
 634         dreq->dreq_gsr     = dreq->dreq_isr;
 635         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 636         dreq->dreq_gss     = dreq->dreq_iss;
 637         dreq->dreq_service = service;
 638
 639         if (dccp_v4_send_response(sk, req))
 640                 goto drop_and_free;
 641
 642         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 643         reqsk_put(req);
 644         return 0;
 645
 646 drop_and_free:
 647         reqsk_free(req);
 648 drop:
 649         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 650         return -1;
 651 }
 652 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 653
 654 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 655 {
 656         struct dccp_hdr *dh = dccp_hdr(skb);
 657
 658         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 659                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 660                         goto reset;
 661                 return 0;
 662         }
 663
 664         /*
 665          *  Step 3: Process LISTEN state
 666          *       If P.type == Request or P contains a valid Init Cookie option,
 667          *            (* Must scan the packet's options to check for Init
 668          *               Cookies.  Only Init Cookies are processed here,
 669          *               however; other options are processed in Step 8.  This
 670          *               scan need only be performed if the endpoint uses Init
 671          *               Cookies *)
 672          *            (* Generate a new socket and switch to that socket *)
 673          *            Set S := new socket for this port pair
 674          *            S.state = RESPOND
 675          *            Choose S.ISS (initial seqno) or set from Init Cookies
 676          *            Initialize S.GAR := S.ISS
 677          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 678          *            Continue with S.state == RESPOND
 679          *            (* A Response packet will be generated in Step 11 *)
 680          *       Otherwise,
 681          *            Generate Reset(No Connection) unless P.type == Reset
 682          *            Drop packet and return
 683          *
 684          * NOTE: the check for the packet types is done in
 685          *       dccp_rcv_state_process
 686          */
 687
 688         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 689                 goto reset;
 690         return 0;
 691
 692 reset:
 693         dccp_v4_ctl_send_reset(sk, skb);
 694         kfree_skb(skb);
 695         return 0;
 696 }
 697 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 698
 699 /**
 700  *      dccp_invalid_packet  -  check for malformed packets
 701  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 702  *      Packets that fail these checks are ignored and do not receive Resets.
 703  */
 704 int dccp_invalid_packet(struct sk_buff *skb)
 705 {
 706         const struct dccp_hdr *dh;
 707         unsigned int cscov;
 708         u8 dccph_doff;
 709
 710         if (skb->pkt_type != PACKET_HOST)
 711                 return 1;
 712
 713         /* If the packet is shorter than 12 bytes, drop packet and return */
 714         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 715                 DCCP_WARN("pskb_may_pull failed\n");
 716                 return 1;
 717         }
 718
 719         dh = dccp_hdr(skb);
 720
 721         /* If P.type is not understood, drop packet and return */
 722         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 723                 DCCP_WARN("invalid packet type\n");
 724                 return 1;
 725         }
 726
 727         /*
 728          * If P.Data Offset is too small for packet type, drop packet and return
 729          */
 730         dccph_doff = dh->dccph_doff;
 731         if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 732                 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
 733                 return 1;
 734         }
 735         /*
 736          * If P.Data Offset is too too large for packet, drop packet and return
 737          */
 738         if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
 739                 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
 740                 return 1;
 741         }
 742         dh = dccp_hdr(skb);
 743         /*
 744          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 745          * has short sequence numbers), drop packet and return
 746          */
 747         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 748             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 749                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 750                           dccp_packet_name(dh->dccph_type));
 751                 return 1;
 752         }
 753
 754         /*
 755          * If P.CsCov is too large for the packet size, drop packet and return.
 756          * This must come _before_ checksumming (not as RFC 4340 suggests).
 757          */
 758         cscov = dccp_csum_coverage(skb);
 759         if (cscov > skb->len) {
 760                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 761                           dh->dccph_cscov, skb->len);
 762                 return 1;
 763         }
 764
 765         /* If header checksum is incorrect, drop packet and return.
 766          * (This step is completed in the AF-dependent functions.) */
 767         skb->csum = skb_checksum(skb, 0, cscov, 0);
 768
 769         return 0;
 770 }
 771 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 772
 773 /* this is called when real data arrives */
 774 static int dccp_v4_rcv(struct sk_buff *skb)
 775 {
 776         const struct dccp_hdr *dh;
 777         const struct iphdr *iph;
 778         bool refcounted;
 779         struct sock *sk;
 780         int min_cov;
 781
 782         /* Step 1: Check header basics */
 783
 784         if (dccp_invalid_packet(skb))
 785                 goto discard_it;
 786
 787         iph = ip_hdr(skb);
 788         /* Step 1: If header checksum is incorrect, drop packet and return */
 789         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 790                 DCCP_WARN("dropped packet with invalid checksum\n");
 791                 goto discard_it;
 792         }
 793
 794         dh = dccp_hdr(skb);
 795
 796         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 797         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 798
 799         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 800                       dccp_packet_name(dh->dccph_type),
 801                       &iph->saddr, ntohs(dh->dccph_sport),
 802                       &iph->daddr, ntohs(dh->dccph_dport),
 803                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 804
 805         if (dccp_packet_without_ack(skb)) {
 806                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 807                 dccp_pr_debug_cat("\n");
 808         } else {
 809                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 810                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 811                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 812         }
 813
 814 lookup:
 815         sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
 816                                dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
 817         if (!sk) {
 818                 dccp_pr_debug("failed to look up flow ID in table and "
 819                               "get corresponding socket\n");
 820                 goto no_dccp_socket;
 821         }
 822
 823         /*
 824          * Step 2:
 825          *      ... or S.state == TIMEWAIT,
 826          *              Generate Reset(No Connection) unless P.type == Reset
 827          *              Drop packet and return
 828          */
 829         if (sk->sk_state == DCCP_TIME_WAIT) {
 830                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 831                 inet_twsk_put(inet_twsk(sk));
 832                 goto no_dccp_socket;
 833         }
 834
 835         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 836                 struct request_sock *req = inet_reqsk(sk);
 837                 struct sock *nsk;
 838
 839                 sk = req->rsk_listener;
 840                 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
 841                         inet_csk_reqsk_queue_drop_and_put(sk, req);
 842                         goto lookup;
 843                 }
 844                 sock_hold(sk);
 845                 refcounted = true;
 846                 nsk = dccp_check_req(sk, skb, req);
 847                 if (!nsk) {
 848                         reqsk_put(req);
 849                         goto discard_and_relse;
 850                 }
 851                 if (nsk == sk) {
 852                         reqsk_put(req);
 853                 } else if (dccp_child_process(sk, nsk, skb)) {
 854                         dccp_v4_ctl_send_reset(sk, skb);
 855                         goto discard_and_relse;
 856                 } else {
 857                         sock_put(sk);
 858                         return 0;
 859                 }
 860         }
 861         /*
 862          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 863          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 864          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 865          */
 866         min_cov = dccp_sk(sk)->dccps_pcrlen;
 867         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 868                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 869                               dh->dccph_cscov, min_cov);
 870                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 871                  *         options (Section 11.7) with Drop Code 0, Protocol
 872                  *         Constraints."                                     */
 873                 goto discard_and_relse;
 874         }
 875
 876         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 877                 goto discard_and_relse;
 878         nf_reset(skb);
 879
 880         return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
 881
 882 no_dccp_socket:
 883         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 884                 goto discard_it;
 885         /*
 886          * Step 2:
 887          *      If no socket ...
 888          *              Generate Reset(No Connection) unless P.type == Reset
 889          *              Drop packet and return
 890          */
 891         if (dh->dccph_type != DCCP_PKT_RESET) {
 892                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 893                                         DCCP_RESET_CODE_NO_CONNECTION;
 894                 dccp_v4_ctl_send_reset(sk, skb);
 895         }
 896
 897 discard_it:
 898         kfree_skb(skb);
 899         return 0;
 900
 901 discard_and_relse:
 902         if (refcounted)
 903                 sock_put(sk);
 904         goto discard_it;
 905 }
 906
 907 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 908         .queue_xmit        = ip_queue_xmit,
 909         .send_check        = dccp_v4_send_check,
 910         .rebuild_header    = inet_sk_rebuild_header,
 911         .conn_request      = dccp_v4_conn_request,
 912         .syn_recv_sock     = dccp_v4_request_recv_sock,
 913         .net_header_len    = sizeof(struct iphdr),
 914         .setsockopt        = ip_setsockopt,
 915         .getsockopt        = ip_getsockopt,
 916         .addr2sockaddr     = inet_csk_addr2sockaddr,
 917         .sockaddr_len      = sizeof(struct sockaddr_in),
 918 #ifdef CONFIG_COMPAT
 919         .compat_setsockopt = compat_ip_setsockopt,
 920         .compat_getsockopt = compat_ip_getsockopt,
 921 #endif
 922 };
 923
 924 static int dccp_v4_init_sock(struct sock *sk)
 925 {
 926         static __u8 dccp_v4_ctl_sock_initialized;
 927         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 928
 929         if (err == 0) {
 930                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 931                         dccp_v4_ctl_sock_initialized = 1;
 932                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 933         }
 934
 935         return err;
 936 }
 937
 938 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 939         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 940 };
 941
 942 static struct proto dccp_v4_prot = {
 943         .name                   = "DCCP",
 944         .owner                  = THIS_MODULE,
 945         .close                  = dccp_close,
 946         .connect                = dccp_v4_connect,
 947         .disconnect             = dccp_disconnect,
 948         .ioctl                  = dccp_ioctl,
 949         .init                   = dccp_v4_init_sock,
 950         .setsockopt             = dccp_setsockopt,
 951         .getsockopt             = dccp_getsockopt,
 952         .sendmsg                = dccp_sendmsg,
 953         .recvmsg                = dccp_recvmsg,
 954         .backlog_rcv            = dccp_v4_do_rcv,
 955         .hash                   = inet_hash,
 956         .unhash                 = inet_unhash,
 957         .accept                 = inet_csk_accept,
 958         .get_port               = inet_csk_get_port,
 959         .shutdown               = dccp_shutdown,
 960         .destroy                = dccp_destroy_sock,
 961         .orphan_count           = &dccp_orphan_count,
 962         .max_header             = MAX_DCCP_HEADER,
 963         .obj_size               = sizeof(struct dccp_sock),
 964         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
 965         .rsk_prot               = &dccp_request_sock_ops,
 966         .twsk_prot              = &dccp_timewait_sock_ops,
 967         .h.hashinfo             = &dccp_hashinfo,
 968 #ifdef CONFIG_COMPAT
 969         .compat_setsockopt      = compat_dccp_setsockopt,
 970         .compat_getsockopt      = compat_dccp_getsockopt,
 971 #endif
 972 };
 973
 974 static const struct net_protocol dccp_v4_protocol = {
 975         .handler        = dccp_v4_rcv,
 976         .err_handler    = dccp_v4_err,
 977         .no_policy      = 1,
 978         .netns_ok       = 1,
 979         .icmp_strict_tag_validation = 1,
 980 };
 981
 982 static const struct proto_ops inet_dccp_ops = {
 983         .family            = PF_INET,
 984         .owner             = THIS_MODULE,
 985         .release           = inet_release,
 986         .bind              = inet_bind,
 987         .connect           = inet_stream_connect,
 988         .socketpair        = sock_no_socketpair,
 989         .accept            = inet_accept,
 990         .getname           = inet_getname,
 991         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 992         .poll              = dccp_poll,
 993         .ioctl             = inet_ioctl,
 994         .gettstamp         = sock_gettstamp,
 995         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 996         .listen            = inet_dccp_listen,
 997         .shutdown          = inet_shutdown,
 998         .setsockopt        = sock_common_setsockopt,
 999         .getsockopt        = sock_common_getsockopt,
1000         .sendmsg           = inet_sendmsg,
1001         .recvmsg           = sock_common_recvmsg,
1002         .mmap              = sock_no_mmap,
1003         .sendpage          = sock_no_sendpage,
1004 #ifdef CONFIG_COMPAT
1005         .compat_setsockopt = compat_sock_common_setsockopt,
1006         .compat_getsockopt = compat_sock_common_getsockopt,
1007 #endif
1008 };
1009
1010 static struct inet_protosw dccp_v4_protosw = {
1011         .type           = SOCK_DCCP,
1012         .protocol       = IPPROTO_DCCP,
1013         .prot           = &dccp_v4_prot,
1014         .ops            = &inet_dccp_ops,
1015         .flags          = INET_PROTOSW_ICSK,
1016 };
1017
1018 static int __net_init dccp_v4_init_net(struct net *net)
1019 {
1020         if (dccp_hashinfo.bhash == NULL)
1021                 return -ESOCKTNOSUPPORT;
1022
1023         return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1024                                     SOCK_DCCP, IPPROTO_DCCP, net);
1025 }
1026
1027 static void __net_exit dccp_v4_exit_net(struct net *net)
1028 {
1029         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1030 }
1031
1032 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1033 {
1034         inet_twsk_purge(&dccp_hashinfo, AF_INET);
1035 }
1036
1037 static struct pernet_operations dccp_v4_ops = {
1038         .init   = dccp_v4_init_net,
1039         .exit   = dccp_v4_exit_net,
1040         .exit_batch = dccp_v4_exit_batch,
1041 };
1042
1043 static int __init dccp_v4_init(void)
1044 {
1045         int err = proto_register(&dccp_v4_prot, 1);
1046
1047         if (err)
1048                 goto out;
1049
1050         inet_register_protosw(&dccp_v4_protosw);
1051
1052         err = register_pernet_subsys(&dccp_v4_ops);
1053         if (err)
1054                 goto out_destroy_ctl_sock;
1055
1056         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1057         if (err)
1058                 goto out_proto_unregister;
1059
1060 out:
1061         return err;
1062 out_proto_unregister:
1063         unregister_pernet_subsys(&dccp_v4_ops);
1064 out_destroy_ctl_sock:
1065         inet_unregister_protosw(&dccp_v4_protosw);
1066         proto_unregister(&dccp_v4_prot);
1067         goto out;
1068 }
1069
1070 static void __exit dccp_v4_exit(void)
1071 {
1072         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1073         unregister_pernet_subsys(&dccp_v4_ops);
1074         inet_unregister_protosw(&dccp_v4_protosw);
1075         proto_unregister(&dccp_v4_prot);
1076 }
1077
1078 module_init(dccp_v4_init);
1079 module_exit(dccp_v4_exit);
1080
1081 /*
1082  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1083  * values directly, Also cover the case where the protocol is not specified,
1084  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1085  */
1086 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1087 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1088 MODULE_LICENSE("GPL");
1089 MODULE_AUTHOR("Arnaldo Carvalho de Melo <[email protected]>");
1090 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");