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         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                 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         struct inet_sock *inet;
 251         const int type = icmp_hdr(skb)->type;
 252         const int code = icmp_hdr(skb)->code;
 253         struct sock *sk;
 254         __u64 seq;
 255         int err;
 256         struct net *net = dev_net(skb->dev);
 257
 258         /* Only need dccph_dport & dccph_sport which are the first
 259          * 4 bytes in dccp header.
 260          * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
 261          */
 262         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
 263         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
 264         dh = (struct dccp_hdr *)(skb->data + offset);
 265
 266         sk = __inet_lookup_established(net, &dccp_hashinfo,
 267                                        iph->daddr, dh->dccph_dport,
 268                                        iph->saddr, ntohs(dh->dccph_sport),
 269                                        inet_iif(skb), 0);
 270         if (!sk) {
 271                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 272                 return -ENOENT;
 273         }
 274
 275         if (sk->sk_state == DCCP_TIME_WAIT) {
 276                 inet_twsk_put(inet_twsk(sk));
 277                 return 0;
 278         }
 279         seq = dccp_hdr_seq(dh);
 280         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 281                 dccp_req_err(sk, seq);
 282                 return 0;
 283         }
 284
 285         bh_lock_sock(sk);
 286         /* If too many ICMPs get dropped on busy
 287          * servers this needs to be solved differently.
 288          */
 289         if (sock_owned_by_user(sk))
 290                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 291
 292         if (sk->sk_state == DCCP_CLOSED)
 293                 goto out;
 294
 295         dp = dccp_sk(sk);
 296         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 297             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 298                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 299                 goto out;
 300         }
 301
 302         switch (type) {
 303         case ICMP_REDIRECT:
 304                 if (!sock_owned_by_user(sk))
 305                         dccp_do_redirect(skb, sk);
 306                 goto out;
 307         case ICMP_SOURCE_QUENCH:
 308                 /* Just silently ignore these. */
 309                 goto out;
 310         case ICMP_PARAMETERPROB:
 311                 err = EPROTO;
 312                 break;
 313         case ICMP_DEST_UNREACH:
 314                 if (code > NR_ICMP_UNREACH)
 315                         goto out;
 316
 317                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 318                         if (!sock_owned_by_user(sk))
 319                                 dccp_do_pmtu_discovery(sk, iph, info);
 320                         goto out;
 321                 }
 322
 323                 err = icmp_err_convert[code].errno;
 324                 break;
 325         case ICMP_TIME_EXCEEDED:
 326                 err = EHOSTUNREACH;
 327                 break;
 328         default:
 329                 goto out;
 330         }
 331
 332         switch (sk->sk_state) {
 333         case DCCP_REQUESTING:
 334         case DCCP_RESPOND:
 335                 if (!sock_owned_by_user(sk)) {
 336                         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 337                         sk->sk_err = err;
 338
 339                         sk_error_report(sk);
 340
 341                         dccp_done(sk);
 342                 } else
 343                         sk->sk_err_soft = err;
 344                 goto out;
 345         }
 346
 347         /* If we've already connected we will keep trying
 348          * until we time out, or the user gives up.
 349          *
 350          * rfc1122 4.2.3.9 allows to consider as hard errors
 351          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 352          * but it is obsoleted by pmtu discovery).
 353          *
 354          * Note, that in modern internet, where routing is unreliable
 355          * and in each dark corner broken firewalls sit, sending random
 356          * errors ordered by their masters even this two messages finally lose
 357          * their original sense (even Linux sends invalid PORT_UNREACHs)
 358          *
 359          * Now we are in compliance with RFCs.
 360          *                                                      --ANK (980905)
 361          */
 362
 363         inet = inet_sk(sk);
 364         if (!sock_owned_by_user(sk) && inet->recverr) {
 365                 sk->sk_err = err;
 366                 sk_error_report(sk);
 367         } else /* Only an error on timeout */
 368                 sk->sk_err_soft = err;
 369 out:
 370         bh_unlock_sock(sk);
 371         sock_put(sk);
 372         return 0;
 373 }
 374
 375 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 376                                       __be32 src, __be32 dst)
 377 {
 378         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 379 }
 380
 381 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 382 {
 383         const struct inet_sock *inet = inet_sk(sk);
 384         struct dccp_hdr *dh = dccp_hdr(skb);
 385
 386         dccp_csum_outgoing(skb);
 387         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 388                                                  inet->inet_saddr,
 389                                                  inet->inet_daddr);
 390 }
 391 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 392
 393 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 394 {
 395         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 396                                            ip_hdr(skb)->saddr,
 397                                            dccp_hdr(skb)->dccph_dport,
 398                                            dccp_hdr(skb)->dccph_sport);
 399 }
 400
 401 /*
 402  * The three way handshake has completed - we got a valid ACK or DATAACK -
 403  * now create the new socket.
 404  *
 405  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 406  */
 407 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
 408                                        struct sk_buff *skb,
 409                                        struct request_sock *req,
 410                                        struct dst_entry *dst,
 411                                        struct request_sock *req_unhash,
 412                                        bool *own_req)
 413 {
 414         struct inet_request_sock *ireq;
 415         struct inet_sock *newinet;
 416         struct sock *newsk;
 417
 418         if (sk_acceptq_is_full(sk))
 419                 goto exit_overflow;
 420
 421         newsk = dccp_create_openreq_child(sk, req, skb);
 422         if (newsk == NULL)
 423                 goto exit_nonewsk;
 424
 425         newinet            = inet_sk(newsk);
 426         ireq               = inet_rsk(req);
 427         sk_daddr_set(newsk, ireq->ir_rmt_addr);
 428         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
 429         newinet->inet_saddr     = ireq->ir_loc_addr;
 430         RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
 431         newinet->mc_index  = inet_iif(skb);
 432         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 433         newinet->inet_id   = get_random_u16();
 434
 435         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 436                 goto put_and_exit;
 437
 438         sk_setup_caps(newsk, dst);
 439
 440         dccp_sync_mss(newsk, dst_mtu(dst));
 441
 442         if (__inet_inherit_port(sk, newsk) < 0)
 443                 goto put_and_exit;
 444         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
 445         if (*own_req)
 446                 ireq->ireq_opt = NULL;
 447         else
 448                 newinet->inet_opt = NULL;
 449         return newsk;
 450
 451 exit_overflow:
 452         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 453 exit_nonewsk:
 454         dst_release(dst);
 455 exit:
 456         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
 457         return NULL;
 458 put_and_exit:
 459         newinet->inet_opt = NULL;
 460         inet_csk_prepare_forced_close(newsk);
 461         dccp_done(newsk);
 462         goto exit;
 463 }
 464 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 465
 466 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 467                                            struct sk_buff *skb)
 468 {
 469         struct rtable *rt;
 470         const struct iphdr *iph = ip_hdr(skb);
 471         struct flowi4 fl4 = {
 472                 .flowi4_oif = inet_iif(skb),
 473                 .daddr = iph->saddr,
 474                 .saddr = iph->daddr,
 475                 .flowi4_tos = RT_CONN_FLAGS(sk),
 476                 .flowi4_proto = sk->sk_protocol,
 477                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 478                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 479         };
 480
 481         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 482         rt = ip_route_output_flow(net, &fl4, sk);
 483         if (IS_ERR(rt)) {
 484                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 485                 return NULL;
 486         }
 487
 488         return &rt->dst;
 489 }
 490
 491 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
 492 {
 493         int err = -1;
 494         struct sk_buff *skb;
 495         struct dst_entry *dst;
 496         struct flowi4 fl4;
 497
 498         dst = inet_csk_route_req(sk, &fl4, req);
 499         if (dst == NULL)
 500                 goto out;
 501
 502         skb = dccp_make_response(sk, dst, req);
 503         if (skb != NULL) {
 504                 const struct inet_request_sock *ireq = inet_rsk(req);
 505                 struct dccp_hdr *dh = dccp_hdr(skb);
 506
 507                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 508                                                               ireq->ir_rmt_addr);
 509                 rcu_read_lock();
 510                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 511                                             ireq->ir_rmt_addr,
 512                                             rcu_dereference(ireq->ireq_opt),
 513                                             inet_sk(sk)->tos);
 514                 rcu_read_unlock();
 515                 err = net_xmit_eval(err);
 516         }
 517
 518 out:
 519         dst_release(dst);
 520         return err;
 521 }
 522
 523 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 524 {
 525         int err;
 526         const struct iphdr *rxiph;
 527         struct sk_buff *skb;
 528         struct dst_entry *dst;
 529         struct net *net = dev_net(skb_dst(rxskb)->dev);
 530         struct dccp_v4_pernet *pn;
 531         struct sock *ctl_sk;
 532
 533         /* Never send a reset in response to a reset. */
 534         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 535                 return;
 536
 537         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 538                 return;
 539
 540         pn = net_generic(net, dccp_v4_pernet_id);
 541         ctl_sk = pn->v4_ctl_sk;
 542         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 543         if (dst == NULL)
 544                 return;
 545
 546         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 547         if (skb == NULL)
 548                 goto out;
 549
 550         rxiph = ip_hdr(rxskb);
 551         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 552                                                                  rxiph->daddr);
 553         skb_dst_set(skb, dst_clone(dst));
 554
 555         local_bh_disable();
 556         bh_lock_sock(ctl_sk);
 557         err = ip_build_and_send_pkt(skb, ctl_sk,
 558                                     rxiph->daddr, rxiph->saddr, NULL,
 559                                     inet_sk(ctl_sk)->tos);
 560         bh_unlock_sock(ctl_sk);
 561
 562         if (net_xmit_eval(err) == 0) {
 563                 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 564                 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 565         }
 566         local_bh_enable();
 567 out:
 568         dst_release(dst);
 569 }
 570
 571 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 572 {
 573         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 574         kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
 575 }
 576
 577 void dccp_syn_ack_timeout(const struct request_sock *req)
 578 {
 579 }
 580 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 581
 582 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 583         .family         = PF_INET,
 584         .obj_size       = sizeof(struct dccp_request_sock),
 585         .rtx_syn_ack    = dccp_v4_send_response,
 586         .send_ack       = dccp_reqsk_send_ack,
 587         .destructor     = dccp_v4_reqsk_destructor,
 588         .send_reset     = dccp_v4_ctl_send_reset,
 589         .syn_ack_timeout = dccp_syn_ack_timeout,
 590 };
 591
 592 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 593 {
 594         struct inet_request_sock *ireq;
 595         struct request_sock *req;
 596         struct dccp_request_sock *dreq;
 597         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 598         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 599
 600         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 601         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 602                 return 0;       /* discard, don't send a reset here */
 603
 604         if (dccp_bad_service_code(sk, service)) {
 605                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 606                 goto drop;
 607         }
 608         /*
 609          * TW buckets are converted to open requests without
 610          * limitations, they conserve resources and peer is
 611          * evidently real one.
 612          */
 613         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 614         if (inet_csk_reqsk_queue_is_full(sk))
 615                 goto drop;
 616
 617         if (sk_acceptq_is_full(sk))
 618                 goto drop;
 619
 620         req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
 621         if (req == NULL)
 622                 goto drop;
 623
 624         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 625                 goto drop_and_free;
 626
 627         dreq = dccp_rsk(req);
 628         if (dccp_parse_options(sk, dreq, skb))
 629                 goto drop_and_free;
 630
 631         if (security_inet_conn_request(sk, skb, req))
 632                 goto drop_and_free;
 633
 634         ireq = inet_rsk(req);
 635         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
 636         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 637         ireq->ir_mark = inet_request_mark(sk, skb);
 638         ireq->ireq_family = AF_INET;
 639         ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
 640
 641         /*
 642          * Step 3: Process LISTEN state
 643          *
 644          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 645          *
 646          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 647          */
 648         dreq->dreq_isr     = dcb->dccpd_seq;
 649         dreq->dreq_gsr     = dreq->dreq_isr;
 650         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 651         dreq->dreq_gss     = dreq->dreq_iss;
 652         dreq->dreq_service = service;
 653
 654         if (dccp_v4_send_response(sk, req))
 655                 goto drop_and_free;
 656
 657         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 658         reqsk_put(req);
 659         return 0;
 660
 661 drop_and_free:
 662         reqsk_free(req);
 663 drop:
 664         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 665         return -1;
 666 }
 667 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 668
 669 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 670 {
 671         struct dccp_hdr *dh = dccp_hdr(skb);
 672
 673         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 674                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 675                         goto reset;
 676                 return 0;
 677         }
 678
 679         /*
 680          *  Step 3: Process LISTEN state
 681          *       If P.type == Request or P contains a valid Init Cookie option,
 682          *            (* Must scan the packet's options to check for Init
 683          *               Cookies.  Only Init Cookies are processed here,
 684          *               however; other options are processed in Step 8.  This
 685          *               scan need only be performed if the endpoint uses Init
 686          *               Cookies *)
 687          *            (* Generate a new socket and switch to that socket *)
 688          *            Set S := new socket for this port pair
 689          *            S.state = RESPOND
 690          *            Choose S.ISS (initial seqno) or set from Init Cookies
 691          *            Initialize S.GAR := S.ISS
 692          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 693          *            Continue with S.state == RESPOND
 694          *            (* A Response packet will be generated in Step 11 *)
 695          *       Otherwise,
 696          *            Generate Reset(No Connection) unless P.type == Reset
 697          *            Drop packet and return
 698          *
 699          * NOTE: the check for the packet types is done in
 700          *       dccp_rcv_state_process
 701          */
 702
 703         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 704                 goto reset;
 705         return 0;
 706
 707 reset:
 708         dccp_v4_ctl_send_reset(sk, skb);
 709         kfree_skb(skb);
 710         return 0;
 711 }
 712 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 713
 714 /**
 715  *      dccp_invalid_packet  -  check for malformed packets
 716  *      @skb: Packet to validate
 717  *
 718  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 719  *      Packets that fail these checks are ignored and do not receive Resets.
 720  */
 721 int dccp_invalid_packet(struct sk_buff *skb)
 722 {
 723         const struct dccp_hdr *dh;
 724         unsigned int cscov;
 725         u8 dccph_doff;
 726
 727         if (skb->pkt_type != PACKET_HOST)
 728                 return 1;
 729
 730         /* If the packet is shorter than 12 bytes, drop packet and return */
 731         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 732                 DCCP_WARN("pskb_may_pull failed\n");
 733                 return 1;
 734         }
 735
 736         dh = dccp_hdr(skb);
 737
 738         /* If P.type is not understood, drop packet and return */
 739         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 740                 DCCP_WARN("invalid packet type\n");
 741                 return 1;
 742         }
 743
 744         /*
 745          * If P.Data Offset is too small for packet type, drop packet and return
 746          */
 747         dccph_doff = dh->dccph_doff;
 748         if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 749                 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
 750                 return 1;
 751         }
 752         /*
 753          * If P.Data Offset is too large for packet, drop packet and return
 754          */
 755         if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
 756                 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
 757                 return 1;
 758         }
 759         dh = dccp_hdr(skb);
 760         /*
 761          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 762          * has short sequence numbers), drop packet and return
 763          */
 764         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 765             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 766                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 767                           dccp_packet_name(dh->dccph_type));
 768                 return 1;
 769         }
 770
 771         /*
 772          * If P.CsCov is too large for the packet size, drop packet and return.
 773          * This must come _before_ checksumming (not as RFC 4340 suggests).
 774          */
 775         cscov = dccp_csum_coverage(skb);
 776         if (cscov > skb->len) {
 777                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 778                           dh->dccph_cscov, skb->len);
 779                 return 1;
 780         }
 781
 782         /* If header checksum is incorrect, drop packet and return.
 783          * (This step is completed in the AF-dependent functions.) */
 784         skb->csum = skb_checksum(skb, 0, cscov, 0);
 785
 786         return 0;
 787 }
 788 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 789
 790 /* this is called when real data arrives */
 791 static int dccp_v4_rcv(struct sk_buff *skb)
 792 {
 793         const struct dccp_hdr *dh;
 794         const struct iphdr *iph;
 795         bool refcounted;
 796         struct sock *sk;
 797         int min_cov;
 798
 799         /* Step 1: Check header basics */
 800
 801         if (dccp_invalid_packet(skb))
 802                 goto discard_it;
 803
 804         iph = ip_hdr(skb);
 805         /* Step 1: If header checksum is incorrect, drop packet and return */
 806         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 807                 DCCP_WARN("dropped packet with invalid checksum\n");
 808                 goto discard_it;
 809         }
 810
 811         dh = dccp_hdr(skb);
 812
 813         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 814         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 815
 816         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 817                       dccp_packet_name(dh->dccph_type),
 818                       &iph->saddr, ntohs(dh->dccph_sport),
 819                       &iph->daddr, ntohs(dh->dccph_dport),
 820                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 821
 822         if (dccp_packet_without_ack(skb)) {
 823                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 824                 dccp_pr_debug_cat("\n");
 825         } else {
 826                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 827                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 828                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 829         }
 830
 831 lookup:
 832         sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
 833                                dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
 834         if (!sk) {
 835                 dccp_pr_debug("failed to look up flow ID in table and "
 836                               "get corresponding socket\n");
 837                 goto no_dccp_socket;
 838         }
 839
 840         /*
 841          * Step 2:
 842          *      ... or S.state == TIMEWAIT,
 843          *              Generate Reset(No Connection) unless P.type == Reset
 844          *              Drop packet and return
 845          */
 846         if (sk->sk_state == DCCP_TIME_WAIT) {
 847                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 848                 inet_twsk_put(inet_twsk(sk));
 849                 goto no_dccp_socket;
 850         }
 851
 852         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 853                 struct request_sock *req = inet_reqsk(sk);
 854                 struct sock *nsk;
 855
 856                 sk = req->rsk_listener;
 857                 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
 858                         inet_csk_reqsk_queue_drop_and_put(sk, req);
 859                         goto lookup;
 860                 }
 861                 sock_hold(sk);
 862                 refcounted = true;
 863                 nsk = dccp_check_req(sk, skb, req);
 864                 if (!nsk) {
 865                         reqsk_put(req);
 866                         goto discard_and_relse;
 867                 }
 868                 if (nsk == sk) {
 869                         reqsk_put(req);
 870                 } else if (dccp_child_process(sk, nsk, skb)) {
 871                         dccp_v4_ctl_send_reset(sk, skb);
 872                         goto discard_and_relse;
 873                 } else {
 874                         sock_put(sk);
 875                         return 0;
 876                 }
 877         }
 878         /*
 879          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 880          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 881          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 882          */
 883         min_cov = dccp_sk(sk)->dccps_pcrlen;
 884         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 885                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 886                               dh->dccph_cscov, min_cov);
 887                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 888                  *         options (Section 11.7) with Drop Code 0, Protocol
 889                  *         Constraints."                                     */
 890                 goto discard_and_relse;
 891         }
 892
 893         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 894                 goto discard_and_relse;
 895         nf_reset_ct(skb);
 896
 897         return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
 898
 899 no_dccp_socket:
 900         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 901                 goto discard_it;
 902         /*
 903          * Step 2:
 904          *      If no socket ...
 905          *              Generate Reset(No Connection) unless P.type == Reset
 906          *              Drop packet and return
 907          */
 908         if (dh->dccph_type != DCCP_PKT_RESET) {
 909                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 910                                         DCCP_RESET_CODE_NO_CONNECTION;
 911                 dccp_v4_ctl_send_reset(sk, skb);
 912         }
 913
 914 discard_it:
 915         kfree_skb(skb);
 916         return 0;
 917
 918 discard_and_relse:
 919         if (refcounted)
 920                 sock_put(sk);
 921         goto discard_it;
 922 }
 923
 924 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 925         .queue_xmit        = ip_queue_xmit,
 926         .send_check        = dccp_v4_send_check,
 927         .rebuild_header    = inet_sk_rebuild_header,
 928         .conn_request      = dccp_v4_conn_request,
 929         .syn_recv_sock     = dccp_v4_request_recv_sock,
 930         .net_header_len    = sizeof(struct iphdr),
 931         .setsockopt        = ip_setsockopt,
 932         .getsockopt        = ip_getsockopt,
 933         .addr2sockaddr     = inet_csk_addr2sockaddr,
 934         .sockaddr_len      = sizeof(struct sockaddr_in),
 935 };
 936
 937 static int dccp_v4_init_sock(struct sock *sk)
 938 {
 939         static __u8 dccp_v4_ctl_sock_initialized;
 940         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 941
 942         if (err == 0) {
 943                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 944                         dccp_v4_ctl_sock_initialized = 1;
 945                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 946         }
 947
 948         return err;
 949 }
 950
 951 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 952         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 953 };
 954
 955 static struct proto dccp_v4_prot = {
 956         .name                   = "DCCP",
 957         .owner                  = THIS_MODULE,
 958         .close                  = dccp_close,
 959         .connect                = dccp_v4_connect,
 960         .disconnect             = dccp_disconnect,
 961         .ioctl                  = dccp_ioctl,
 962         .init                   = dccp_v4_init_sock,
 963         .setsockopt             = dccp_setsockopt,
 964         .getsockopt             = dccp_getsockopt,
 965         .sendmsg                = dccp_sendmsg,
 966         .recvmsg                = dccp_recvmsg,
 967         .backlog_rcv            = dccp_v4_do_rcv,
 968         .hash                   = inet_hash,
 969         .unhash                 = inet_unhash,
 970         .accept                 = inet_csk_accept,
 971         .get_port               = inet_csk_get_port,
 972         .shutdown               = dccp_shutdown,
 973         .destroy                = dccp_destroy_sock,
 974         .orphan_count           = &dccp_orphan_count,
 975         .max_header             = MAX_DCCP_HEADER,
 976         .obj_size               = sizeof(struct dccp_sock),
 977         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
 978         .rsk_prot               = &dccp_request_sock_ops,
 979         .twsk_prot              = &dccp_timewait_sock_ops,
 980         .h.hashinfo             = &dccp_hashinfo,
 981 };
 982
 983 static const struct net_protocol dccp_v4_protocol = {
 984         .handler        = dccp_v4_rcv,
 985         .err_handler    = dccp_v4_err,
 986         .no_policy      = 1,
 987         .icmp_strict_tag_validation = 1,
 988 };
 989
 990 static const struct proto_ops inet_dccp_ops = {
 991         .family            = PF_INET,
 992         .owner             = THIS_MODULE,
 993         .release           = inet_release,
 994         .bind              = inet_bind,
 995         .connect           = inet_stream_connect,
 996         .socketpair        = sock_no_socketpair,
 997         .accept            = inet_accept,
 998         .getname           = inet_getname,
 999         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1000         .poll              = dccp_poll,
1001         .ioctl             = inet_ioctl,
1002         .gettstamp         = sock_gettstamp,
1003         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1004         .listen            = inet_dccp_listen,
1005         .shutdown          = inet_shutdown,
1006         .setsockopt        = sock_common_setsockopt,
1007         .getsockopt        = sock_common_getsockopt,
1008         .sendmsg           = inet_sendmsg,
1009         .recvmsg           = sock_common_recvmsg,
1010         .mmap              = sock_no_mmap,
1011         .sendpage          = sock_no_sendpage,
1012 };
1013
1014 static struct inet_protosw dccp_v4_protosw = {
1015         .type           = SOCK_DCCP,
1016         .protocol       = IPPROTO_DCCP,
1017         .prot           = &dccp_v4_prot,
1018         .ops            = &inet_dccp_ops,
1019         .flags          = INET_PROTOSW_ICSK,
1020 };
1021
1022 static int __net_init dccp_v4_init_net(struct net *net)
1023 {
1024         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1025
1026         if (dccp_hashinfo.bhash == NULL)
1027                 return -ESOCKTNOSUPPORT;
1028
1029         return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET,
1030                                     SOCK_DCCP, IPPROTO_DCCP, net);
1031 }
1032
1033 static void __net_exit dccp_v4_exit_net(struct net *net)
1034 {
1035         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1036
1037         inet_ctl_sock_destroy(pn->v4_ctl_sk);
1038 }
1039
1040 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1041 {
1042         inet_twsk_purge(&dccp_hashinfo, AF_INET);
1043 }
1044
1045 static struct pernet_operations dccp_v4_ops = {
1046         .init   = dccp_v4_init_net,
1047         .exit   = dccp_v4_exit_net,
1048         .exit_batch = dccp_v4_exit_batch,
1049         .id     = &dccp_v4_pernet_id,
1050         .size   = sizeof(struct dccp_v4_pernet),
1051 };
1052
1053 static int __init dccp_v4_init(void)
1054 {
1055         int err = proto_register(&dccp_v4_prot, 1);
1056
1057         if (err)
1058                 goto out;
1059
1060         inet_register_protosw(&dccp_v4_protosw);
1061
1062         err = register_pernet_subsys(&dccp_v4_ops);
1063         if (err)
1064                 goto out_destroy_ctl_sock;
1065
1066         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1067         if (err)
1068                 goto out_proto_unregister;
1069
1070 out:
1071         return err;
1072 out_proto_unregister:
1073         unregister_pernet_subsys(&dccp_v4_ops);
1074 out_destroy_ctl_sock:
1075         inet_unregister_protosw(&dccp_v4_protosw);
1076         proto_unregister(&dccp_v4_prot);
1077         goto out;
1078 }
1079
1080 static void __exit dccp_v4_exit(void)
1081 {
1082         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1083         unregister_pernet_subsys(&dccp_v4_ops);
1084         inet_unregister_protosw(&dccp_v4_protosw);
1085         proto_unregister(&dccp_v4_prot);
1086 }
1087
1088 module_init(dccp_v4_init);
1089 module_exit(dccp_v4_exit);
1090
1091 /*
1092  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1093  * values directly, Also cover the case where the protocol is not specified,
1094  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1095  */
1096 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1097 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1098 MODULE_LICENSE("GPL");
1099 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1100 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");