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 #include <net/netns/generic.h>
  27
  28 #include "ackvec.h"
  29 #include "ccid.h"
  30 #include "dccp.h"
  31 #include "feat.h"
  32
  33 struct dccp_v4_pernet {
  34         struct sock *v4_ctl_sk;
  35 };
  36
  37 static unsigned int dccp_v4_pernet_id __read_mostly;
  38
  39 /*
  40  * The per-net v4_ctl_sk socket is used for responding to
  41  * the Out-of-the-blue (OOTB) packets. A control sock will be created
  42  * for this socket at the initialization time.
  43  */
  44
  45 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  46 {
  47         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
  48         struct inet_sock *inet = inet_sk(sk);
  49         struct dccp_sock *dp = dccp_sk(sk);
  50         __be16 orig_sport, orig_dport;
  51         __be32 daddr, nexthop;
  52         struct flowi4 *fl4;
  53         struct rtable *rt;
  54         int err;
  55         struct ip_options_rcu *inet_opt;
  56
  57         dp->dccps_role = DCCP_ROLE_CLIENT;
  58
  59         if (addr_len < sizeof(struct sockaddr_in))
  60                 return -EINVAL;
  61
  62         if (usin->sin_family != AF_INET)
  63                 return -EAFNOSUPPORT;
  64
  65         nexthop = daddr = usin->sin_addr.s_addr;
  66
  67         inet_opt = rcu_dereference_protected(inet->inet_opt,
  68                                              lockdep_sock_is_held(sk));
  69         if (inet_opt != NULL && inet_opt->opt.srr) {
  70                 if (daddr == 0)
  71                         return -EINVAL;
  72                 nexthop = inet_opt->opt.faddr;
  73         }
  74
  75         orig_sport = inet->inet_sport;
  76         orig_dport = usin->sin_port;
  77         fl4 = &inet->cork.fl.u.ip4;
  78         rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
  79                               sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport,
  80                               orig_dport, sk);
  81         if (IS_ERR(rt))
  82                 return PTR_ERR(rt);
  83
  84         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  85                 ip_rt_put(rt);
  86                 return -ENETUNREACH;
  87         }
  88
  89         if (inet_opt == NULL || !inet_opt->opt.srr)
  90                 daddr = fl4->daddr;
  91
  92         if (inet->inet_saddr == 0) {
  93                 err = inet_bhash2_update_saddr(sk,  &fl4->saddr, AF_INET);
  94                 if (err) {
  95                         ip_rt_put(rt);
  96                         return err;
  97                 }
  98         } else {
  99                 sk_rcv_saddr_set(sk, inet->inet_saddr);
 100         }
 101
 102         inet->inet_dport = usin->sin_port;
 103         sk_daddr_set(sk, daddr);
 104
 105         inet_csk(sk)->icsk_ext_hdr_len = 0;
 106         if (inet_opt)
 107                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
 108         /*
 109          * Socket identity is still unknown (sport may be zero).
 110          * However we set state to DCCP_REQUESTING and not releasing socket
 111          * lock select source port, enter ourselves into the hash tables and
 112          * complete initialization after this.
 113          */
 114         dccp_set_state(sk, DCCP_REQUESTING);
 115         err = inet_hash_connect(&dccp_death_row, sk);
 116         if (err != 0)
 117                 goto failure;
 118
 119         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 120                                inet->inet_sport, inet->inet_dport, sk);
 121         if (IS_ERR(rt)) {
 122                 err = PTR_ERR(rt);
 123                 rt = NULL;
 124                 goto failure;
 125         }
 126         /* OK, now commit destination to socket.  */
 127         sk_setup_caps(sk, &rt->dst);
 128
 129         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 130                                                     inet->inet_daddr,
 131                                                     inet->inet_sport,
 132                                                     inet->inet_dport);
 133         atomic_set(&inet->inet_id, get_random_u16());
 134
 135         err = dccp_connect(sk);
 136         rt = NULL;
 137         if (err != 0)
 138                 goto failure;
 139 out:
 140         return err;
 141 failure:
 142         /*
 143          * This unhashes the socket and releases the local port, if necessary.
 144          */
 145         dccp_set_state(sk, DCCP_CLOSED);
 146         inet_bhash2_reset_saddr(sk);
 147         ip_rt_put(rt);
 148         sk->sk_route_caps = 0;
 149         inet->inet_dport = 0;
 150         goto out;
 151 }
 152 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 153
 154 /*
 155  * This routine does path mtu discovery as defined in RFC1191.
 156  */
 157 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 158                                           const struct iphdr *iph,
 159                                           u32 mtu)
 160 {
 161         struct dst_entry *dst;
 162         const struct inet_sock *inet = inet_sk(sk);
 163         const struct dccp_sock *dp = dccp_sk(sk);
 164
 165         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 166          * send out by Linux are always < 576bytes so they should go through
 167          * unfragmented).
 168          */
 169         if (sk->sk_state == DCCP_LISTEN)
 170                 return;
 171
 172         dst = inet_csk_update_pmtu(sk, mtu);
 173         if (!dst)
 174                 return;
 175
 176         /* Something is about to be wrong... Remember soft error
 177          * for the case, if this connection will not able to recover.
 178          */
 179         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 180                 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE);
 181
 182         mtu = dst_mtu(dst);
 183
 184         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 185             ip_sk_accept_pmtu(sk) &&
 186             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 187                 dccp_sync_mss(sk, mtu);
 188
 189                 /*
 190                  * From RFC 4340, sec. 14.1:
 191                  *
 192                  *      DCCP-Sync packets are the best choice for upward
 193                  *      probing, since DCCP-Sync probes do not risk application
 194                  *      data loss.
 195                  */
 196                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 197         } /* else let the usual retransmit timer handle it */
 198 }
 199
 200 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
 201 {
 202         struct dst_entry *dst = __sk_dst_check(sk, 0);
 203
 204         if (dst)
 205                 dst->ops->redirect(dst, sk, skb);
 206 }
 207
 208 void dccp_req_err(struct sock *sk, u64 seq)
 209         {
 210         struct request_sock *req = inet_reqsk(sk);
 211         struct net *net = sock_net(sk);
 212
 213         /*
 214          * ICMPs are not backlogged, hence we cannot get an established
 215          * socket here.
 216          */
 217         if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
 218                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 219         } else {
 220                 /*
 221                  * Still in RESPOND, just remove it silently.
 222                  * There is no good way to pass the error to the newly
 223                  * created socket, and POSIX does not want network
 224                  * errors returned from accept().
 225                  */
 226                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 227         }
 228         reqsk_put(req);
 229 }
 230 EXPORT_SYMBOL(dccp_req_err);
 231
 232 /*
 233  * This routine is called by the ICMP module when it gets some sort of error
 234  * condition. If err < 0 then the socket should be closed and the error
 235  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 236  * After adjustment header points to the first 8 bytes of the tcp header. We
 237  * need to find the appropriate port.
 238  *
 239  * The locking strategy used here is very "optimistic". When someone else
 240  * accesses the socket the ICMP is just dropped and for some paths there is no
 241  * check at all. A more general error queue to queue errors for later handling
 242  * is probably better.
 243  */
 244 static int dccp_v4_err(struct sk_buff *skb, u32 info)
 245 {
 246         const struct iphdr *iph = (struct iphdr *)skb->data;
 247         const u8 offset = iph->ihl << 2;
 248         const struct dccp_hdr *dh;
 249         struct dccp_sock *dp;
 250         const int type = icmp_hdr(skb)->type;
 251         const int code = icmp_hdr(skb)->code;
 252         struct sock *sk;
 253         __u64 seq;
 254         int err;
 255         struct net *net = dev_net(skb->dev);
 256
 257         /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
 258          * which is in byte 7 of the dccp header.
 259          * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
 260          *
 261          * Later on, we want to access the sequence number fields, which are
 262          * beyond 8 bytes, so we have to pskb_may_pull() ourselves.
 263          */
 264         dh = (struct dccp_hdr *)(skb->data + offset);
 265         if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
 266                 return -EINVAL;
 267         iph = (struct iphdr *)skb->data;
 268         dh = (struct dccp_hdr *)(skb->data + offset);
 269
 270         sk = __inet_lookup_established(net, &dccp_hashinfo,
 271                                        iph->daddr, dh->dccph_dport,
 272                                        iph->saddr, ntohs(dh->dccph_sport),
 273                                        inet_iif(skb), 0);
 274         if (!sk) {
 275                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 276                 return -ENOENT;
 277         }
 278
 279         if (sk->sk_state == DCCP_TIME_WAIT) {
 280                 inet_twsk_put(inet_twsk(sk));
 281                 return 0;
 282         }
 283         seq = dccp_hdr_seq(dh);
 284         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 285                 dccp_req_err(sk, seq);
 286                 return 0;
 287         }
 288
 289         bh_lock_sock(sk);
 290         /* If too many ICMPs get dropped on busy
 291          * servers this needs to be solved differently.
 292          */
 293         if (sock_owned_by_user(sk))
 294                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 295
 296         if (sk->sk_state == DCCP_CLOSED)
 297                 goto out;
 298
 299         dp = dccp_sk(sk);
 300         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 301             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 302                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 303                 goto out;
 304         }
 305
 306         switch (type) {
 307         case ICMP_REDIRECT:
 308                 if (!sock_owned_by_user(sk))
 309                         dccp_do_redirect(skb, sk);
 310                 goto out;
 311         case ICMP_SOURCE_QUENCH:
 312                 /* Just silently ignore these. */
 313                 goto out;
 314         case ICMP_PARAMETERPROB:
 315                 err = EPROTO;
 316                 break;
 317         case ICMP_DEST_UNREACH:
 318                 if (code > NR_ICMP_UNREACH)
 319                         goto out;
 320
 321                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 322                         if (!sock_owned_by_user(sk))
 323                                 dccp_do_pmtu_discovery(sk, iph, info);
 324                         goto out;
 325                 }
 326
 327                 err = icmp_err_convert[code].errno;
 328                 break;
 329         case ICMP_TIME_EXCEEDED:
 330                 err = EHOSTUNREACH;
 331                 break;
 332         default:
 333                 goto out;
 334         }
 335
 336         switch (sk->sk_state) {
 337         case DCCP_REQUESTING:
 338         case DCCP_RESPOND:
 339                 if (!sock_owned_by_user(sk)) {
 340                         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 341                         sk->sk_err = err;
 342
 343                         sk_error_report(sk);
 344
 345                         dccp_done(sk);
 346                 } else {
 347                         WRITE_ONCE(sk->sk_err_soft, err);
 348                 }
 349                 goto out;
 350         }
 351
 352         /* If we've already connected we will keep trying
 353          * until we time out, or the user gives up.
 354          *
 355          * rfc1122 4.2.3.9 allows to consider as hard errors
 356          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 357          * but it is obsoleted by pmtu discovery).
 358          *
 359          * Note, that in modern internet, where routing is unreliable
 360          * and in each dark corner broken firewalls sit, sending random
 361          * errors ordered by their masters even this two messages finally lose
 362          * their original sense (even Linux sends invalid PORT_UNREACHs)
 363          *
 364          * Now we are in compliance with RFCs.
 365          *                                                      --ANK (980905)
 366          */
 367
 368         if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
 369                 sk->sk_err = err;
 370                 sk_error_report(sk);
 371         } else { /* Only an error on timeout */
 372                 WRITE_ONCE(sk->sk_err_soft, err);
 373         }
 374 out:
 375         bh_unlock_sock(sk);
 376         sock_put(sk);
 377         return 0;
 378 }
 379
 380 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 381                                       __be32 src, __be32 dst)
 382 {
 383         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 384 }
 385
 386 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 387 {
 388         const struct inet_sock *inet = inet_sk(sk);
 389         struct dccp_hdr *dh = dccp_hdr(skb);
 390
 391         dccp_csum_outgoing(skb);
 392         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 393                                                  inet->inet_saddr,
 394                                                  inet->inet_daddr);
 395 }
 396 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 397
 398 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 399 {
 400         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 401                                            ip_hdr(skb)->saddr,
 402                                            dccp_hdr(skb)->dccph_dport,
 403                                            dccp_hdr(skb)->dccph_sport);
 404 }
 405
 406 /*
 407  * The three way handshake has completed - we got a valid ACK or DATAACK -
 408  * now create the new socket.
 409  *
 410  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 411  */
 412 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
 413                                        struct sk_buff *skb,
 414                                        struct request_sock *req,
 415                                        struct dst_entry *dst,
 416                                        struct request_sock *req_unhash,
 417                                        bool *own_req)
 418 {
 419         struct inet_request_sock *ireq;
 420         struct inet_sock *newinet;
 421         struct sock *newsk;
 422
 423         if (sk_acceptq_is_full(sk))
 424                 goto exit_overflow;
 425
 426         newsk = dccp_create_openreq_child(sk, req, skb);
 427         if (newsk == NULL)
 428                 goto exit_nonewsk;
 429
 430         newinet            = inet_sk(newsk);
 431         ireq               = inet_rsk(req);
 432         sk_daddr_set(newsk, ireq->ir_rmt_addr);
 433         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
 434         newinet->inet_saddr     = ireq->ir_loc_addr;
 435         RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
 436         newinet->mc_index  = inet_iif(skb);
 437         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 438         atomic_set(&newinet->inet_id, get_random_u16());
 439
 440         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 441                 goto put_and_exit;
 442
 443         sk_setup_caps(newsk, dst);
 444
 445         dccp_sync_mss(newsk, dst_mtu(dst));
 446
 447         if (__inet_inherit_port(sk, newsk) < 0)
 448                 goto put_and_exit;
 449         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
 450         if (*own_req)
 451                 ireq->ireq_opt = NULL;
 452         else
 453                 newinet->inet_opt = NULL;
 454         return newsk;
 455
 456 exit_overflow:
 457         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 458 exit_nonewsk:
 459         dst_release(dst);
 460 exit:
 461         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
 462         return NULL;
 463 put_and_exit:
 464         newinet->inet_opt = NULL;
 465         inet_csk_prepare_forced_close(newsk);
 466         dccp_done(newsk);
 467         goto exit;
 468 }
 469 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 470
 471 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 472                                            struct sk_buff *skb)
 473 {
 474         struct rtable *rt;
 475         const struct iphdr *iph = ip_hdr(skb);
 476         struct flowi4 fl4 = {
 477                 .flowi4_oif = inet_iif(skb),
 478                 .daddr = iph->saddr,
 479                 .saddr = iph->daddr,
 480                 .flowi4_tos = ip_sock_rt_tos(sk),
 481                 .flowi4_scope = ip_sock_rt_scope(sk),
 482                 .flowi4_proto = sk->sk_protocol,
 483                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 484                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 485         };
 486
 487         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 488         rt = ip_route_output_flow(net, &fl4, sk);
 489         if (IS_ERR(rt)) {
 490                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 491                 return NULL;
 492         }
 493
 494         return &rt->dst;
 495 }
 496
 497 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
 498 {
 499         int err = -1;
 500         struct sk_buff *skb;
 501         struct dst_entry *dst;
 502         struct flowi4 fl4;
 503
 504         dst = inet_csk_route_req(sk, &fl4, req);
 505         if (dst == NULL)
 506                 goto out;
 507
 508         skb = dccp_make_response(sk, dst, req);
 509         if (skb != NULL) {
 510                 const struct inet_request_sock *ireq = inet_rsk(req);
 511                 struct dccp_hdr *dh = dccp_hdr(skb);
 512
 513                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 514                                                               ireq->ir_rmt_addr);
 515                 rcu_read_lock();
 516                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 517                                             ireq->ir_rmt_addr,
 518                                             rcu_dereference(ireq->ireq_opt),
 519                                             inet_sk(sk)->tos);
 520                 rcu_read_unlock();
 521                 err = net_xmit_eval(err);
 522         }
 523
 524 out:
 525         dst_release(dst);
 526         return err;
 527 }
 528
 529 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 530 {
 531         int err;
 532         const struct iphdr *rxiph;
 533         struct sk_buff *skb;
 534         struct dst_entry *dst;
 535         struct net *net = dev_net(skb_dst(rxskb)->dev);
 536         struct dccp_v4_pernet *pn;
 537         struct sock *ctl_sk;
 538
 539         /* Never send a reset in response to a reset. */
 540         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 541                 return;
 542
 543         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 544                 return;
 545
 546         pn = net_generic(net, dccp_v4_pernet_id);
 547         ctl_sk = pn->v4_ctl_sk;
 548         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 549         if (dst == NULL)
 550                 return;
 551
 552         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 553         if (skb == NULL)
 554                 goto out;
 555
 556         rxiph = ip_hdr(rxskb);
 557         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 558                                                                  rxiph->daddr);
 559         skb_dst_set(skb, dst_clone(dst));
 560
 561         local_bh_disable();
 562         bh_lock_sock(ctl_sk);
 563         err = ip_build_and_send_pkt(skb, ctl_sk,
 564                                     rxiph->daddr, rxiph->saddr, NULL,
 565                                     inet_sk(ctl_sk)->tos);
 566         bh_unlock_sock(ctl_sk);
 567
 568         if (net_xmit_eval(err) == 0) {
 569                 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 570                 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 571         }
 572         local_bh_enable();
 573 out:
 574         dst_release(dst);
 575 }
 576
 577 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 578 {
 579         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 580         kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
 581 }
 582
 583 void dccp_syn_ack_timeout(const struct request_sock *req)
 584 {
 585 }
 586 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 587
 588 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 589         .family         = PF_INET,
 590         .obj_size       = sizeof(struct dccp_request_sock),
 591         .rtx_syn_ack    = dccp_v4_send_response,
 592         .send_ack       = dccp_reqsk_send_ack,
 593         .destructor     = dccp_v4_reqsk_destructor,
 594         .send_reset     = dccp_v4_ctl_send_reset,
 595         .syn_ack_timeout = dccp_syn_ack_timeout,
 596 };
 597
 598 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 599 {
 600         struct inet_request_sock *ireq;
 601         struct request_sock *req;
 602         struct dccp_request_sock *dreq;
 603         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 604         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 605
 606         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 607         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 608                 return 0;       /* discard, don't send a reset here */
 609
 610         if (dccp_bad_service_code(sk, service)) {
 611                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 612                 goto drop;
 613         }
 614         /*
 615          * TW buckets are converted to open requests without
 616          * limitations, they conserve resources and peer is
 617          * evidently real one.
 618          */
 619         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 620         if (inet_csk_reqsk_queue_is_full(sk))
 621                 goto drop;
 622
 623         if (sk_acceptq_is_full(sk))
 624                 goto drop;
 625
 626         req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
 627         if (req == NULL)
 628                 goto drop;
 629
 630         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 631                 goto drop_and_free;
 632
 633         dreq = dccp_rsk(req);
 634         if (dccp_parse_options(sk, dreq, skb))
 635                 goto drop_and_free;
 636
 637         if (security_inet_conn_request(sk, skb, req))
 638                 goto drop_and_free;
 639
 640         ireq = inet_rsk(req);
 641         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
 642         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 643         ireq->ir_mark = inet_request_mark(sk, skb);
 644         ireq->ireq_family = AF_INET;
 645         ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
 646
 647         /*
 648          * Step 3: Process LISTEN state
 649          *
 650          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 651          *
 652          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 653          */
 654         dreq->dreq_isr     = dcb->dccpd_seq;
 655         dreq->dreq_gsr     = dreq->dreq_isr;
 656         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 657         dreq->dreq_gss     = dreq->dreq_iss;
 658         dreq->dreq_service = service;
 659
 660         if (dccp_v4_send_response(sk, req))
 661                 goto drop_and_free;
 662
 663         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 664         reqsk_put(req);
 665         return 0;
 666
 667 drop_and_free:
 668         reqsk_free(req);
 669 drop:
 670         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 671         return -1;
 672 }
 673 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 674
 675 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 676 {
 677         struct dccp_hdr *dh = dccp_hdr(skb);
 678
 679         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 680                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 681                         goto reset;
 682                 return 0;
 683         }
 684
 685         /*
 686          *  Step 3: Process LISTEN state
 687          *       If P.type == Request or P contains a valid Init Cookie option,
 688          *            (* Must scan the packet's options to check for Init
 689          *               Cookies.  Only Init Cookies are processed here,
 690          *               however; other options are processed in Step 8.  This
 691          *               scan need only be performed if the endpoint uses Init
 692          *               Cookies *)
 693          *            (* Generate a new socket and switch to that socket *)
 694          *            Set S := new socket for this port pair
 695          *            S.state = RESPOND
 696          *            Choose S.ISS (initial seqno) or set from Init Cookies
 697          *            Initialize S.GAR := S.ISS
 698          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 699          *            Continue with S.state == RESPOND
 700          *            (* A Response packet will be generated in Step 11 *)
 701          *       Otherwise,
 702          *            Generate Reset(No Connection) unless P.type == Reset
 703          *            Drop packet and return
 704          *
 705          * NOTE: the check for the packet types is done in
 706          *       dccp_rcv_state_process
 707          */
 708
 709         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 710                 goto reset;
 711         return 0;
 712
 713 reset:
 714         dccp_v4_ctl_send_reset(sk, skb);
 715         kfree_skb(skb);
 716         return 0;
 717 }
 718 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 719
 720 /**
 721  *      dccp_invalid_packet  -  check for malformed packets
 722  *      @skb: Packet to validate
 723  *
 724  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 725  *      Packets that fail these checks are ignored and do not receive Resets.
 726  */
 727 int dccp_invalid_packet(struct sk_buff *skb)
 728 {
 729         const struct dccp_hdr *dh;
 730         unsigned int cscov;
 731         u8 dccph_doff;
 732
 733         if (skb->pkt_type != PACKET_HOST)
 734                 return 1;
 735
 736         /* If the packet is shorter than 12 bytes, drop packet and return */
 737         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 738                 DCCP_WARN("pskb_may_pull failed\n");
 739                 return 1;
 740         }
 741
 742         dh = dccp_hdr(skb);
 743
 744         /* If P.type is not understood, drop packet and return */
 745         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 746                 DCCP_WARN("invalid packet type\n");
 747                 return 1;
 748         }
 749
 750         /*
 751          * If P.Data Offset is too small for packet type, drop packet and return
 752          */
 753         dccph_doff = dh->dccph_doff;
 754         if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 755                 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
 756                 return 1;
 757         }
 758         /*
 759          * If P.Data Offset is too large for packet, drop packet and return
 760          */
 761         if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
 762                 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
 763                 return 1;
 764         }
 765         dh = dccp_hdr(skb);
 766         /*
 767          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 768          * has short sequence numbers), drop packet and return
 769          */
 770         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 771             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 772                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 773                           dccp_packet_name(dh->dccph_type));
 774                 return 1;
 775         }
 776
 777         /*
 778          * If P.CsCov is too large for the packet size, drop packet and return.
 779          * This must come _before_ checksumming (not as RFC 4340 suggests).
 780          */
 781         cscov = dccp_csum_coverage(skb);
 782         if (cscov > skb->len) {
 783                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 784                           dh->dccph_cscov, skb->len);
 785                 return 1;
 786         }
 787
 788         /* If header checksum is incorrect, drop packet and return.
 789          * (This step is completed in the AF-dependent functions.) */
 790         skb->csum = skb_checksum(skb, 0, cscov, 0);
 791
 792         return 0;
 793 }
 794 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 795
 796 /* this is called when real data arrives */
 797 static int dccp_v4_rcv(struct sk_buff *skb)
 798 {
 799         const struct dccp_hdr *dh;
 800         const struct iphdr *iph;
 801         bool refcounted;
 802         struct sock *sk;
 803         int min_cov;
 804
 805         /* Step 1: Check header basics */
 806
 807         if (dccp_invalid_packet(skb))
 808                 goto discard_it;
 809
 810         iph = ip_hdr(skb);
 811         /* Step 1: If header checksum is incorrect, drop packet and return */
 812         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 813                 DCCP_WARN("dropped packet with invalid checksum\n");
 814                 goto discard_it;
 815         }
 816
 817         dh = dccp_hdr(skb);
 818
 819         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 820         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 821
 822         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 823                       dccp_packet_name(dh->dccph_type),
 824                       &iph->saddr, ntohs(dh->dccph_sport),
 825                       &iph->daddr, ntohs(dh->dccph_dport),
 826                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 827
 828         if (dccp_packet_without_ack(skb)) {
 829                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 830                 dccp_pr_debug_cat("\n");
 831         } else {
 832                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 833                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 834                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 835         }
 836
 837 lookup:
 838         sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
 839                                dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
 840         if (!sk) {
 841                 dccp_pr_debug("failed to look up flow ID in table and "
 842                               "get corresponding socket\n");
 843                 goto no_dccp_socket;
 844         }
 845
 846         /*
 847          * Step 2:
 848          *      ... or S.state == TIMEWAIT,
 849          *              Generate Reset(No Connection) unless P.type == Reset
 850          *              Drop packet and return
 851          */
 852         if (sk->sk_state == DCCP_TIME_WAIT) {
 853                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 854                 inet_twsk_put(inet_twsk(sk));
 855                 goto no_dccp_socket;
 856         }
 857
 858         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 859                 struct request_sock *req = inet_reqsk(sk);
 860                 struct sock *nsk;
 861
 862                 sk = req->rsk_listener;
 863                 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
 864                         inet_csk_reqsk_queue_drop_and_put(sk, req);
 865                         goto lookup;
 866                 }
 867                 sock_hold(sk);
 868                 refcounted = true;
 869                 nsk = dccp_check_req(sk, skb, req);
 870                 if (!nsk) {
 871                         reqsk_put(req);
 872                         goto discard_and_relse;
 873                 }
 874                 if (nsk == sk) {
 875                         reqsk_put(req);
 876                 } else if (dccp_child_process(sk, nsk, skb)) {
 877                         dccp_v4_ctl_send_reset(sk, skb);
 878                         goto discard_and_relse;
 879                 } else {
 880                         sock_put(sk);
 881                         return 0;
 882                 }
 883         }
 884         /*
 885          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 886          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 887          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 888          */
 889         min_cov = dccp_sk(sk)->dccps_pcrlen;
 890         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 891                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 892                               dh->dccph_cscov, min_cov);
 893                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 894                  *         options (Section 11.7) with Drop Code 0, Protocol
 895                  *         Constraints."                                     */
 896                 goto discard_and_relse;
 897         }
 898
 899         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 900                 goto discard_and_relse;
 901         nf_reset_ct(skb);
 902
 903         return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
 904
 905 no_dccp_socket:
 906         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 907                 goto discard_it;
 908         /*
 909          * Step 2:
 910          *      If no socket ...
 911          *              Generate Reset(No Connection) unless P.type == Reset
 912          *              Drop packet and return
 913          */
 914         if (dh->dccph_type != DCCP_PKT_RESET) {
 915                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 916                                         DCCP_RESET_CODE_NO_CONNECTION;
 917                 dccp_v4_ctl_send_reset(sk, skb);
 918         }
 919
 920 discard_it:
 921         kfree_skb(skb);
 922         return 0;
 923
 924 discard_and_relse:
 925         if (refcounted)
 926                 sock_put(sk);
 927         goto discard_it;
 928 }
 929
 930 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 931         .queue_xmit        = ip_queue_xmit,
 932         .send_check        = dccp_v4_send_check,
 933         .rebuild_header    = inet_sk_rebuild_header,
 934         .conn_request      = dccp_v4_conn_request,
 935         .syn_recv_sock     = dccp_v4_request_recv_sock,
 936         .net_header_len    = sizeof(struct iphdr),
 937         .setsockopt        = ip_setsockopt,
 938         .getsockopt        = ip_getsockopt,
 939         .addr2sockaddr     = inet_csk_addr2sockaddr,
 940         .sockaddr_len      = sizeof(struct sockaddr_in),
 941 };
 942
 943 static int dccp_v4_init_sock(struct sock *sk)
 944 {
 945         static __u8 dccp_v4_ctl_sock_initialized;
 946         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 947
 948         if (err == 0) {
 949                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 950                         dccp_v4_ctl_sock_initialized = 1;
 951                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 952         }
 953
 954         return err;
 955 }
 956
 957 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 958         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 959 };
 960
 961 static struct proto dccp_v4_prot = {
 962         .name                   = "DCCP",
 963         .owner                  = THIS_MODULE,
 964         .close                  = dccp_close,
 965         .connect                = dccp_v4_connect,
 966         .disconnect             = dccp_disconnect,
 967         .ioctl                  = dccp_ioctl,
 968         .init                   = dccp_v4_init_sock,
 969         .setsockopt             = dccp_setsockopt,
 970         .getsockopt             = dccp_getsockopt,
 971         .sendmsg                = dccp_sendmsg,
 972         .recvmsg                = dccp_recvmsg,
 973         .backlog_rcv            = dccp_v4_do_rcv,
 974         .hash                   = inet_hash,
 975         .unhash                 = inet_unhash,
 976         .accept                 = inet_csk_accept,
 977         .get_port               = inet_csk_get_port,
 978         .shutdown               = dccp_shutdown,
 979         .destroy                = dccp_destroy_sock,
 980         .orphan_count           = &dccp_orphan_count,
 981         .max_header             = MAX_DCCP_HEADER,
 982         .obj_size               = sizeof(struct dccp_sock),
 983         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
 984         .rsk_prot               = &dccp_request_sock_ops,
 985         .twsk_prot              = &dccp_timewait_sock_ops,
 986         .h.hashinfo             = &dccp_hashinfo,
 987 };
 988
 989 static const struct net_protocol dccp_v4_protocol = {
 990         .handler        = dccp_v4_rcv,
 991         .err_handler    = dccp_v4_err,
 992         .no_policy      = 1,
 993         .icmp_strict_tag_validation = 1,
 994 };
 995
 996 static const struct proto_ops inet_dccp_ops = {
 997         .family            = PF_INET,
 998         .owner             = THIS_MODULE,
 999         .release           = inet_release,
1000         .bind              = inet_bind,
1001         .connect           = inet_stream_connect,
1002         .socketpair        = sock_no_socketpair,
1003         .accept            = inet_accept,
1004         .getname           = inet_getname,
1005         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1006         .poll              = dccp_poll,
1007         .ioctl             = inet_ioctl,
1008         .gettstamp         = sock_gettstamp,
1009         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1010         .listen            = inet_dccp_listen,
1011         .shutdown          = inet_shutdown,
1012         .setsockopt        = sock_common_setsockopt,
1013         .getsockopt        = sock_common_getsockopt,
1014         .sendmsg           = inet_sendmsg,
1015         .recvmsg           = sock_common_recvmsg,
1016         .mmap              = sock_no_mmap,
1017 };
1018
1019 static struct inet_protosw dccp_v4_protosw = {
1020         .type           = SOCK_DCCP,
1021         .protocol       = IPPROTO_DCCP,
1022         .prot           = &dccp_v4_prot,
1023         .ops            = &inet_dccp_ops,
1024         .flags          = INET_PROTOSW_ICSK,
1025 };
1026
1027 static int __net_init dccp_v4_init_net(struct net *net)
1028 {
1029         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1030
1031         if (dccp_hashinfo.bhash == NULL)
1032                 return -ESOCKTNOSUPPORT;
1033
1034         return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET,
1035                                     SOCK_DCCP, IPPROTO_DCCP, net);
1036 }
1037
1038 static void __net_exit dccp_v4_exit_net(struct net *net)
1039 {
1040         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1041
1042         inet_ctl_sock_destroy(pn->v4_ctl_sk);
1043 }
1044
1045 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1046 {
1047         inet_twsk_purge(&dccp_hashinfo, AF_INET);
1048 }
1049
1050 static struct pernet_operations dccp_v4_ops = {
1051         .init   = dccp_v4_init_net,
1052         .exit   = dccp_v4_exit_net,
1053         .exit_batch = dccp_v4_exit_batch,
1054         .id     = &dccp_v4_pernet_id,
1055         .size   = sizeof(struct dccp_v4_pernet),
1056 };
1057
1058 static int __init dccp_v4_init(void)
1059 {
1060         int err = proto_register(&dccp_v4_prot, 1);
1061
1062         if (err)
1063                 goto out;
1064
1065         inet_register_protosw(&dccp_v4_protosw);
1066
1067         err = register_pernet_subsys(&dccp_v4_ops);
1068         if (err)
1069                 goto out_destroy_ctl_sock;
1070
1071         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1072         if (err)
1073                 goto out_proto_unregister;
1074
1075 out:
1076         return err;
1077 out_proto_unregister:
1078         unregister_pernet_subsys(&dccp_v4_ops);
1079 out_destroy_ctl_sock:
1080         inet_unregister_protosw(&dccp_v4_protosw);
1081         proto_unregister(&dccp_v4_prot);
1082         goto out;
1083 }
1084
1085 static void __exit dccp_v4_exit(void)
1086 {
1087         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1088         unregister_pernet_subsys(&dccp_v4_ops);
1089         inet_unregister_protosw(&dccp_v4_protosw);
1090         proto_unregister(&dccp_v4_prot);
1091 }
1092
1093 module_init(dccp_v4_init);
1094 module_exit(dccp_v4_exit);
1095
1096 /*
1097  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1098  * values directly, Also cover the case where the protocol is not specified,
1099  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1100  */
1101 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1102 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1103 MODULE_LICENSE("GPL");
1104 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1105 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");