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                               RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
  80                               IPPROTO_DCCP,
  81                               orig_sport, orig_dport, sk);
  82         if (IS_ERR(rt))
  83                 return PTR_ERR(rt);
  84
  85         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
  86                 ip_rt_put(rt);
  87                 return -ENETUNREACH;
  88         }
  89
  90         if (inet_opt == NULL || !inet_opt->opt.srr)
  91                 daddr = fl4->daddr;
  92
  93         if (inet->inet_saddr == 0)
  94                 inet->inet_saddr = fl4->saddr;
  95         sk_rcv_saddr_set(sk, inet->inet_saddr);
  96         inet->inet_dport = usin->sin_port;
  97         sk_daddr_set(sk, daddr);
  98
  99         inet_csk(sk)->icsk_ext_hdr_len = 0;
 100         if (inet_opt)
 101                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
 102         /*
 103          * Socket identity is still unknown (sport may be zero).
 104          * However we set state to DCCP_REQUESTING and not releasing socket
 105          * lock select source port, enter ourselves into the hash tables and
 106          * complete initialization after this.
 107          */
 108         dccp_set_state(sk, DCCP_REQUESTING);
 109         err = inet_hash_connect(&dccp_death_row, sk);
 110         if (err != 0)
 111                 goto failure;
 112
 113         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 114                                inet->inet_sport, inet->inet_dport, sk);
 115         if (IS_ERR(rt)) {
 116                 err = PTR_ERR(rt);
 117                 rt = NULL;
 118                 goto failure;
 119         }
 120         /* OK, now commit destination to socket.  */
 121         sk_setup_caps(sk, &rt->dst);
 122
 123         dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
 124                                                     inet->inet_daddr,
 125                                                     inet->inet_sport,
 126                                                     inet->inet_dport);
 127         inet->inet_id = prandom_u32();
 128
 129         err = dccp_connect(sk);
 130         rt = NULL;
 131         if (err != 0)
 132                 goto failure;
 133 out:
 134         return err;
 135 failure:
 136         /*
 137          * This unhashes the socket and releases the local port, if necessary.
 138          */
 139         dccp_set_state(sk, DCCP_CLOSED);
 140         ip_rt_put(rt);
 141         sk->sk_route_caps = 0;
 142         inet->inet_dport = 0;
 143         goto out;
 144 }
 145 EXPORT_SYMBOL_GPL(dccp_v4_connect);
 146
 147 /*
 148  * This routine does path mtu discovery as defined in RFC1191.
 149  */
 150 static inline void dccp_do_pmtu_discovery(struct sock *sk,
 151                                           const struct iphdr *iph,
 152                                           u32 mtu)
 153 {
 154         struct dst_entry *dst;
 155         const struct inet_sock *inet = inet_sk(sk);
 156         const struct dccp_sock *dp = dccp_sk(sk);
 157
 158         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
 159          * send out by Linux are always < 576bytes so they should go through
 160          * unfragmented).
 161          */
 162         if (sk->sk_state == DCCP_LISTEN)
 163                 return;
 164
 165         dst = inet_csk_update_pmtu(sk, mtu);
 166         if (!dst)
 167                 return;
 168
 169         /* Something is about to be wrong... Remember soft error
 170          * for the case, if this connection will not able to recover.
 171          */
 172         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 173                 sk->sk_err_soft = EMSGSIZE;
 174
 175         mtu = dst_mtu(dst);
 176
 177         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 178             ip_sk_accept_pmtu(sk) &&
 179             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 180                 dccp_sync_mss(sk, mtu);
 181
 182                 /*
 183                  * From RFC 4340, sec. 14.1:
 184                  *
 185                  *      DCCP-Sync packets are the best choice for upward
 186                  *      probing, since DCCP-Sync probes do not risk application
 187                  *      data loss.
 188                  */
 189                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 190         } /* else let the usual retransmit timer handle it */
 191 }
 192
 193 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
 194 {
 195         struct dst_entry *dst = __sk_dst_check(sk, 0);
 196
 197         if (dst)
 198                 dst->ops->redirect(dst, sk, skb);
 199 }
 200
 201 void dccp_req_err(struct sock *sk, u64 seq)
 202         {
 203         struct request_sock *req = inet_reqsk(sk);
 204         struct net *net = sock_net(sk);
 205
 206         /*
 207          * ICMPs are not backlogged, hence we cannot get an established
 208          * socket here.
 209          */
 210         if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
 211                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 212         } else {
 213                 /*
 214                  * Still in RESPOND, just remove it silently.
 215                  * There is no good way to pass the error to the newly
 216                  * created socket, and POSIX does not want network
 217                  * errors returned from accept().
 218                  */
 219                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 220         }
 221         reqsk_put(req);
 222 }
 223 EXPORT_SYMBOL(dccp_req_err);
 224
 225 /*
 226  * This routine is called by the ICMP module when it gets some sort of error
 227  * condition. If err < 0 then the socket should be closed and the error
 228  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
 229  * After adjustment header points to the first 8 bytes of the tcp header. We
 230  * need to find the appropriate port.
 231  *
 232  * The locking strategy used here is very "optimistic". When someone else
 233  * accesses the socket the ICMP is just dropped and for some paths there is no
 234  * check at all. A more general error queue to queue errors for later handling
 235  * is probably better.
 236  */
 237 static int dccp_v4_err(struct sk_buff *skb, u32 info)
 238 {
 239         const struct iphdr *iph = (struct iphdr *)skb->data;
 240         const u8 offset = iph->ihl << 2;
 241         const struct dccp_hdr *dh;
 242         struct dccp_sock *dp;
 243         struct inet_sock *inet;
 244         const int type = icmp_hdr(skb)->type;
 245         const int code = icmp_hdr(skb)->code;
 246         struct sock *sk;
 247         __u64 seq;
 248         int err;
 249         struct net *net = dev_net(skb->dev);
 250
 251         /* Only need dccph_dport & dccph_sport which are the first
 252          * 4 bytes in dccp header.
 253          * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
 254          */
 255         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
 256         BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
 257         dh = (struct dccp_hdr *)(skb->data + offset);
 258
 259         sk = __inet_lookup_established(net, &dccp_hashinfo,
 260                                        iph->daddr, dh->dccph_dport,
 261                                        iph->saddr, ntohs(dh->dccph_sport),
 262                                        inet_iif(skb), 0);
 263         if (!sk) {
 264                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 265                 return -ENOENT;
 266         }
 267
 268         if (sk->sk_state == DCCP_TIME_WAIT) {
 269                 inet_twsk_put(inet_twsk(sk));
 270                 return 0;
 271         }
 272         seq = dccp_hdr_seq(dh);
 273         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 274                 dccp_req_err(sk, seq);
 275                 return 0;
 276         }
 277
 278         bh_lock_sock(sk);
 279         /* If too many ICMPs get dropped on busy
 280          * servers this needs to be solved differently.
 281          */
 282         if (sock_owned_by_user(sk))
 283                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 284
 285         if (sk->sk_state == DCCP_CLOSED)
 286                 goto out;
 287
 288         dp = dccp_sk(sk);
 289         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
 290             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
 291                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 292                 goto out;
 293         }
 294
 295         switch (type) {
 296         case ICMP_REDIRECT:
 297                 if (!sock_owned_by_user(sk))
 298                         dccp_do_redirect(skb, sk);
 299                 goto out;
 300         case ICMP_SOURCE_QUENCH:
 301                 /* Just silently ignore these. */
 302                 goto out;
 303         case ICMP_PARAMETERPROB:
 304                 err = EPROTO;
 305                 break;
 306         case ICMP_DEST_UNREACH:
 307                 if (code > NR_ICMP_UNREACH)
 308                         goto out;
 309
 310                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 311                         if (!sock_owned_by_user(sk))
 312                                 dccp_do_pmtu_discovery(sk, iph, info);
 313                         goto out;
 314                 }
 315
 316                 err = icmp_err_convert[code].errno;
 317                 break;
 318         case ICMP_TIME_EXCEEDED:
 319                 err = EHOSTUNREACH;
 320                 break;
 321         default:
 322                 goto out;
 323         }
 324
 325         switch (sk->sk_state) {
 326         case DCCP_REQUESTING:
 327         case DCCP_RESPOND:
 328                 if (!sock_owned_by_user(sk)) {
 329                         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 330                         sk->sk_err = err;
 331
 332                         sk_error_report(sk);
 333
 334                         dccp_done(sk);
 335                 } else
 336                         sk->sk_err_soft = err;
 337                 goto out;
 338         }
 339
 340         /* If we've already connected we will keep trying
 341          * until we time out, or the user gives up.
 342          *
 343          * rfc1122 4.2.3.9 allows to consider as hard errors
 344          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 345          * but it is obsoleted by pmtu discovery).
 346          *
 347          * Note, that in modern internet, where routing is unreliable
 348          * and in each dark corner broken firewalls sit, sending random
 349          * errors ordered by their masters even this two messages finally lose
 350          * their original sense (even Linux sends invalid PORT_UNREACHs)
 351          *
 352          * Now we are in compliance with RFCs.
 353          *                                                      --ANK (980905)
 354          */
 355
 356         inet = inet_sk(sk);
 357         if (!sock_owned_by_user(sk) && inet->recverr) {
 358                 sk->sk_err = err;
 359                 sk_error_report(sk);
 360         } else /* Only an error on timeout */
 361                 sk->sk_err_soft = err;
 362 out:
 363         bh_unlock_sock(sk);
 364         sock_put(sk);
 365         return 0;
 366 }
 367
 368 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
 369                                       __be32 src, __be32 dst)
 370 {
 371         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
 372 }
 373
 374 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 375 {
 376         const struct inet_sock *inet = inet_sk(sk);
 377         struct dccp_hdr *dh = dccp_hdr(skb);
 378
 379         dccp_csum_outgoing(skb);
 380         dh->dccph_checksum = dccp_v4_csum_finish(skb,
 381                                                  inet->inet_saddr,
 382                                                  inet->inet_daddr);
 383 }
 384 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
 385
 386 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
 387 {
 388         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
 389                                            ip_hdr(skb)->saddr,
 390                                            dccp_hdr(skb)->dccph_dport,
 391                                            dccp_hdr(skb)->dccph_sport);
 392 }
 393
 394 /*
 395  * The three way handshake has completed - we got a valid ACK or DATAACK -
 396  * now create the new socket.
 397  *
 398  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
 399  */
 400 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
 401                                        struct sk_buff *skb,
 402                                        struct request_sock *req,
 403                                        struct dst_entry *dst,
 404                                        struct request_sock *req_unhash,
 405                                        bool *own_req)
 406 {
 407         struct inet_request_sock *ireq;
 408         struct inet_sock *newinet;
 409         struct sock *newsk;
 410
 411         if (sk_acceptq_is_full(sk))
 412                 goto exit_overflow;
 413
 414         newsk = dccp_create_openreq_child(sk, req, skb);
 415         if (newsk == NULL)
 416                 goto exit_nonewsk;
 417
 418         newinet            = inet_sk(newsk);
 419         ireq               = inet_rsk(req);
 420         sk_daddr_set(newsk, ireq->ir_rmt_addr);
 421         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
 422         newinet->inet_saddr     = ireq->ir_loc_addr;
 423         RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
 424         newinet->mc_index  = inet_iif(skb);
 425         newinet->mc_ttl    = ip_hdr(skb)->ttl;
 426         newinet->inet_id   = prandom_u32();
 427
 428         if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
 429                 goto put_and_exit;
 430
 431         sk_setup_caps(newsk, dst);
 432
 433         dccp_sync_mss(newsk, dst_mtu(dst));
 434
 435         if (__inet_inherit_port(sk, newsk) < 0)
 436                 goto put_and_exit;
 437         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
 438         if (*own_req)
 439                 ireq->ireq_opt = NULL;
 440         else
 441                 newinet->inet_opt = NULL;
 442         return newsk;
 443
 444 exit_overflow:
 445         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 446 exit_nonewsk:
 447         dst_release(dst);
 448 exit:
 449         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
 450         return NULL;
 451 put_and_exit:
 452         newinet->inet_opt = NULL;
 453         inet_csk_prepare_forced_close(newsk);
 454         dccp_done(newsk);
 455         goto exit;
 456 }
 457 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
 458
 459 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 460                                            struct sk_buff *skb)
 461 {
 462         struct rtable *rt;
 463         const struct iphdr *iph = ip_hdr(skb);
 464         struct flowi4 fl4 = {
 465                 .flowi4_oif = inet_iif(skb),
 466                 .daddr = iph->saddr,
 467                 .saddr = iph->daddr,
 468                 .flowi4_tos = RT_CONN_FLAGS(sk),
 469                 .flowi4_proto = sk->sk_protocol,
 470                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
 471                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
 472         };
 473
 474         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 475         rt = ip_route_output_flow(net, &fl4, sk);
 476         if (IS_ERR(rt)) {
 477                 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 478                 return NULL;
 479         }
 480
 481         return &rt->dst;
 482 }
 483
 484 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
 485 {
 486         int err = -1;
 487         struct sk_buff *skb;
 488         struct dst_entry *dst;
 489         struct flowi4 fl4;
 490
 491         dst = inet_csk_route_req(sk, &fl4, req);
 492         if (dst == NULL)
 493                 goto out;
 494
 495         skb = dccp_make_response(sk, dst, req);
 496         if (skb != NULL) {
 497                 const struct inet_request_sock *ireq = inet_rsk(req);
 498                 struct dccp_hdr *dh = dccp_hdr(skb);
 499
 500                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
 501                                                               ireq->ir_rmt_addr);
 502                 rcu_read_lock();
 503                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 504                                             ireq->ir_rmt_addr,
 505                                             rcu_dereference(ireq->ireq_opt),
 506                                             inet_sk(sk)->tos);
 507                 rcu_read_unlock();
 508                 err = net_xmit_eval(err);
 509         }
 510
 511 out:
 512         dst_release(dst);
 513         return err;
 514 }
 515
 516 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 517 {
 518         int err;
 519         const struct iphdr *rxiph;
 520         struct sk_buff *skb;
 521         struct dst_entry *dst;
 522         struct net *net = dev_net(skb_dst(rxskb)->dev);
 523         struct dccp_v4_pernet *pn;
 524         struct sock *ctl_sk;
 525
 526         /* Never send a reset in response to a reset. */
 527         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
 528                 return;
 529
 530         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
 531                 return;
 532
 533         pn = net_generic(net, dccp_v4_pernet_id);
 534         ctl_sk = pn->v4_ctl_sk;
 535         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
 536         if (dst == NULL)
 537                 return;
 538
 539         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
 540         if (skb == NULL)
 541                 goto out;
 542
 543         rxiph = ip_hdr(rxskb);
 544         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
 545                                                                  rxiph->daddr);
 546         skb_dst_set(skb, dst_clone(dst));
 547
 548         local_bh_disable();
 549         bh_lock_sock(ctl_sk);
 550         err = ip_build_and_send_pkt(skb, ctl_sk,
 551                                     rxiph->daddr, rxiph->saddr, NULL,
 552                                     inet_sk(ctl_sk)->tos);
 553         bh_unlock_sock(ctl_sk);
 554
 555         if (net_xmit_eval(err) == 0) {
 556                 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 557                 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 558         }
 559         local_bh_enable();
 560 out:
 561         dst_release(dst);
 562 }
 563
 564 static void dccp_v4_reqsk_destructor(struct request_sock *req)
 565 {
 566         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
 567         kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
 568 }
 569
 570 void dccp_syn_ack_timeout(const struct request_sock *req)
 571 {
 572 }
 573 EXPORT_SYMBOL(dccp_syn_ack_timeout);
 574
 575 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
 576         .family         = PF_INET,
 577         .obj_size       = sizeof(struct dccp_request_sock),
 578         .rtx_syn_ack    = dccp_v4_send_response,
 579         .send_ack       = dccp_reqsk_send_ack,
 580         .destructor     = dccp_v4_reqsk_destructor,
 581         .send_reset     = dccp_v4_ctl_send_reset,
 582         .syn_ack_timeout = dccp_syn_ack_timeout,
 583 };
 584
 585 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 586 {
 587         struct inet_request_sock *ireq;
 588         struct request_sock *req;
 589         struct dccp_request_sock *dreq;
 590         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
 591         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 592
 593         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
 594         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 595                 return 0;       /* discard, don't send a reset here */
 596
 597         if (dccp_bad_service_code(sk, service)) {
 598                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
 599                 goto drop;
 600         }
 601         /*
 602          * TW buckets are converted to open requests without
 603          * limitations, they conserve resources and peer is
 604          * evidently real one.
 605          */
 606         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 607         if (inet_csk_reqsk_queue_is_full(sk))
 608                 goto drop;
 609
 610         if (sk_acceptq_is_full(sk))
 611                 goto drop;
 612
 613         req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
 614         if (req == NULL)
 615                 goto drop;
 616
 617         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
 618                 goto drop_and_free;
 619
 620         dreq = dccp_rsk(req);
 621         if (dccp_parse_options(sk, dreq, skb))
 622                 goto drop_and_free;
 623
 624         if (security_inet_conn_request(sk, skb, req))
 625                 goto drop_and_free;
 626
 627         ireq = inet_rsk(req);
 628         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
 629         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 630         ireq->ir_mark = inet_request_mark(sk, skb);
 631         ireq->ireq_family = AF_INET;
 632         ireq->ir_iif = sk->sk_bound_dev_if;
 633
 634         /*
 635          * Step 3: Process LISTEN state
 636          *
 637          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 638          *
 639          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
 640          */
 641         dreq->dreq_isr     = dcb->dccpd_seq;
 642         dreq->dreq_gsr     = dreq->dreq_isr;
 643         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
 644         dreq->dreq_gss     = dreq->dreq_iss;
 645         dreq->dreq_service = service;
 646
 647         if (dccp_v4_send_response(sk, req))
 648                 goto drop_and_free;
 649
 650         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
 651         reqsk_put(req);
 652         return 0;
 653
 654 drop_and_free:
 655         reqsk_free(req);
 656 drop:
 657         __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
 658         return -1;
 659 }
 660 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
 661
 662 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 663 {
 664         struct dccp_hdr *dh = dccp_hdr(skb);
 665
 666         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
 667                 if (dccp_rcv_established(sk, skb, dh, skb->len))
 668                         goto reset;
 669                 return 0;
 670         }
 671
 672         /*
 673          *  Step 3: Process LISTEN state
 674          *       If P.type == Request or P contains a valid Init Cookie option,
 675          *            (* Must scan the packet's options to check for Init
 676          *               Cookies.  Only Init Cookies are processed here,
 677          *               however; other options are processed in Step 8.  This
 678          *               scan need only be performed if the endpoint uses Init
 679          *               Cookies *)
 680          *            (* Generate a new socket and switch to that socket *)
 681          *            Set S := new socket for this port pair
 682          *            S.state = RESPOND
 683          *            Choose S.ISS (initial seqno) or set from Init Cookies
 684          *            Initialize S.GAR := S.ISS
 685          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 686          *            Continue with S.state == RESPOND
 687          *            (* A Response packet will be generated in Step 11 *)
 688          *       Otherwise,
 689          *            Generate Reset(No Connection) unless P.type == Reset
 690          *            Drop packet and return
 691          *
 692          * NOTE: the check for the packet types is done in
 693          *       dccp_rcv_state_process
 694          */
 695
 696         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
 697                 goto reset;
 698         return 0;
 699
 700 reset:
 701         dccp_v4_ctl_send_reset(sk, skb);
 702         kfree_skb(skb);
 703         return 0;
 704 }
 705 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 706
 707 /**
 708  *      dccp_invalid_packet  -  check for malformed packets
 709  *      @skb: Packet to validate
 710  *
 711  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
 712  *      Packets that fail these checks are ignored and do not receive Resets.
 713  */
 714 int dccp_invalid_packet(struct sk_buff *skb)
 715 {
 716         const struct dccp_hdr *dh;
 717         unsigned int cscov;
 718         u8 dccph_doff;
 719
 720         if (skb->pkt_type != PACKET_HOST)
 721                 return 1;
 722
 723         /* If the packet is shorter than 12 bytes, drop packet and return */
 724         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
 725                 DCCP_WARN("pskb_may_pull failed\n");
 726                 return 1;
 727         }
 728
 729         dh = dccp_hdr(skb);
 730
 731         /* If P.type is not understood, drop packet and return */
 732         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 733                 DCCP_WARN("invalid packet type\n");
 734                 return 1;
 735         }
 736
 737         /*
 738          * If P.Data Offset is too small for packet type, drop packet and return
 739          */
 740         dccph_doff = dh->dccph_doff;
 741         if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
 742                 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
 743                 return 1;
 744         }
 745         /*
 746          * If P.Data Offset is too large for packet, drop packet and return
 747          */
 748         if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
 749                 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
 750                 return 1;
 751         }
 752         dh = dccp_hdr(skb);
 753         /*
 754          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
 755          * has short sequence numbers), drop packet and return
 756          */
 757         if ((dh->dccph_type < DCCP_PKT_DATA    ||
 758             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
 759                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
 760                           dccp_packet_name(dh->dccph_type));
 761                 return 1;
 762         }
 763
 764         /*
 765          * If P.CsCov is too large for the packet size, drop packet and return.
 766          * This must come _before_ checksumming (not as RFC 4340 suggests).
 767          */
 768         cscov = dccp_csum_coverage(skb);
 769         if (cscov > skb->len) {
 770                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
 771                           dh->dccph_cscov, skb->len);
 772                 return 1;
 773         }
 774
 775         /* If header checksum is incorrect, drop packet and return.
 776          * (This step is completed in the AF-dependent functions.) */
 777         skb->csum = skb_checksum(skb, 0, cscov, 0);
 778
 779         return 0;
 780 }
 781 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 782
 783 /* this is called when real data arrives */
 784 static int dccp_v4_rcv(struct sk_buff *skb)
 785 {
 786         const struct dccp_hdr *dh;
 787         const struct iphdr *iph;
 788         bool refcounted;
 789         struct sock *sk;
 790         int min_cov;
 791
 792         /* Step 1: Check header basics */
 793
 794         if (dccp_invalid_packet(skb))
 795                 goto discard_it;
 796
 797         iph = ip_hdr(skb);
 798         /* Step 1: If header checksum is incorrect, drop packet and return */
 799         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
 800                 DCCP_WARN("dropped packet with invalid checksum\n");
 801                 goto discard_it;
 802         }
 803
 804         dh = dccp_hdr(skb);
 805
 806         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
 807         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
 808
 809         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
 810                       dccp_packet_name(dh->dccph_type),
 811                       &iph->saddr, ntohs(dh->dccph_sport),
 812                       &iph->daddr, ntohs(dh->dccph_dport),
 813                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 814
 815         if (dccp_packet_without_ack(skb)) {
 816                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
 817                 dccp_pr_debug_cat("\n");
 818         } else {
 819                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
 820                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
 821                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
 822         }
 823
 824 lookup:
 825         sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
 826                                dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
 827         if (!sk) {
 828                 dccp_pr_debug("failed to look up flow ID in table and "
 829                               "get corresponding socket\n");
 830                 goto no_dccp_socket;
 831         }
 832
 833         /*
 834          * Step 2:
 835          *      ... or S.state == TIMEWAIT,
 836          *              Generate Reset(No Connection) unless P.type == Reset
 837          *              Drop packet and return
 838          */
 839         if (sk->sk_state == DCCP_TIME_WAIT) {
 840                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
 841                 inet_twsk_put(inet_twsk(sk));
 842                 goto no_dccp_socket;
 843         }
 844
 845         if (sk->sk_state == DCCP_NEW_SYN_RECV) {
 846                 struct request_sock *req = inet_reqsk(sk);
 847                 struct sock *nsk;
 848
 849                 sk = req->rsk_listener;
 850                 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
 851                         inet_csk_reqsk_queue_drop_and_put(sk, req);
 852                         goto lookup;
 853                 }
 854                 sock_hold(sk);
 855                 refcounted = true;
 856                 nsk = dccp_check_req(sk, skb, req);
 857                 if (!nsk) {
 858                         reqsk_put(req);
 859                         goto discard_and_relse;
 860                 }
 861                 if (nsk == sk) {
 862                         reqsk_put(req);
 863                 } else if (dccp_child_process(sk, nsk, skb)) {
 864                         dccp_v4_ctl_send_reset(sk, skb);
 865                         goto discard_and_relse;
 866                 } else {
 867                         sock_put(sk);
 868                         return 0;
 869                 }
 870         }
 871         /*
 872          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
 873          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
 874          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
 875          */
 876         min_cov = dccp_sk(sk)->dccps_pcrlen;
 877         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
 878                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
 879                               dh->dccph_cscov, min_cov);
 880                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
 881                  *         options (Section 11.7) with Drop Code 0, Protocol
 882                  *         Constraints."                                     */
 883                 goto discard_and_relse;
 884         }
 885
 886         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 887                 goto discard_and_relse;
 888         nf_reset_ct(skb);
 889
 890         return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
 891
 892 no_dccp_socket:
 893         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 894                 goto discard_it;
 895         /*
 896          * Step 2:
 897          *      If no socket ...
 898          *              Generate Reset(No Connection) unless P.type == Reset
 899          *              Drop packet and return
 900          */
 901         if (dh->dccph_type != DCCP_PKT_RESET) {
 902                 DCCP_SKB_CB(skb)->dccpd_reset_code =
 903                                         DCCP_RESET_CODE_NO_CONNECTION;
 904                 dccp_v4_ctl_send_reset(sk, skb);
 905         }
 906
 907 discard_it:
 908         kfree_skb(skb);
 909         return 0;
 910
 911 discard_and_relse:
 912         if (refcounted)
 913                 sock_put(sk);
 914         goto discard_it;
 915 }
 916
 917 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 918         .queue_xmit        = ip_queue_xmit,
 919         .send_check        = dccp_v4_send_check,
 920         .rebuild_header    = inet_sk_rebuild_header,
 921         .conn_request      = dccp_v4_conn_request,
 922         .syn_recv_sock     = dccp_v4_request_recv_sock,
 923         .net_header_len    = sizeof(struct iphdr),
 924         .setsockopt        = ip_setsockopt,
 925         .getsockopt        = ip_getsockopt,
 926         .addr2sockaddr     = inet_csk_addr2sockaddr,
 927         .sockaddr_len      = sizeof(struct sockaddr_in),
 928 };
 929
 930 static int dccp_v4_init_sock(struct sock *sk)
 931 {
 932         static __u8 dccp_v4_ctl_sock_initialized;
 933         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
 934
 935         if (err == 0) {
 936                 if (unlikely(!dccp_v4_ctl_sock_initialized))
 937                         dccp_v4_ctl_sock_initialized = 1;
 938                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
 939         }
 940
 941         return err;
 942 }
 943
 944 static struct timewait_sock_ops dccp_timewait_sock_ops = {
 945         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 946 };
 947
 948 static struct proto dccp_v4_prot = {
 949         .name                   = "DCCP",
 950         .owner                  = THIS_MODULE,
 951         .close                  = dccp_close,
 952         .connect                = dccp_v4_connect,
 953         .disconnect             = dccp_disconnect,
 954         .ioctl                  = dccp_ioctl,
 955         .init                   = dccp_v4_init_sock,
 956         .setsockopt             = dccp_setsockopt,
 957         .getsockopt             = dccp_getsockopt,
 958         .sendmsg                = dccp_sendmsg,
 959         .recvmsg                = dccp_recvmsg,
 960         .backlog_rcv            = dccp_v4_do_rcv,
 961         .hash                   = inet_hash,
 962         .unhash                 = inet_unhash,
 963         .accept                 = inet_csk_accept,
 964         .get_port               = inet_csk_get_port,
 965         .shutdown               = dccp_shutdown,
 966         .destroy                = dccp_destroy_sock,
 967         .orphan_count           = &dccp_orphan_count,
 968         .max_header             = MAX_DCCP_HEADER,
 969         .obj_size               = sizeof(struct dccp_sock),
 970         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
 971         .rsk_prot               = &dccp_request_sock_ops,
 972         .twsk_prot              = &dccp_timewait_sock_ops,
 973         .h.hashinfo             = &dccp_hashinfo,
 974 };
 975
 976 static const struct net_protocol dccp_v4_protocol = {
 977         .handler        = dccp_v4_rcv,
 978         .err_handler    = dccp_v4_err,
 979         .no_policy      = 1,
 980         .icmp_strict_tag_validation = 1,
 981 };
 982
 983 static const struct proto_ops inet_dccp_ops = {
 984         .family            = PF_INET,
 985         .owner             = THIS_MODULE,
 986         .release           = inet_release,
 987         .bind              = inet_bind,
 988         .connect           = inet_stream_connect,
 989         .socketpair        = sock_no_socketpair,
 990         .accept            = inet_accept,
 991         .getname           = inet_getname,
 992         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
 993         .poll              = dccp_poll,
 994         .ioctl             = inet_ioctl,
 995         .gettstamp         = sock_gettstamp,
 996         /* FIXME: work on inet_listen to rename it to sock_common_listen */
 997         .listen            = inet_dccp_listen,
 998         .shutdown          = inet_shutdown,
 999         .setsockopt        = sock_common_setsockopt,
1000         .getsockopt        = sock_common_getsockopt,
1001         .sendmsg           = inet_sendmsg,
1002         .recvmsg           = sock_common_recvmsg,
1003         .mmap              = sock_no_mmap,
1004         .sendpage          = sock_no_sendpage,
1005 };
1006
1007 static struct inet_protosw dccp_v4_protosw = {
1008         .type           = SOCK_DCCP,
1009         .protocol       = IPPROTO_DCCP,
1010         .prot           = &dccp_v4_prot,
1011         .ops            = &inet_dccp_ops,
1012         .flags          = INET_PROTOSW_ICSK,
1013 };
1014
1015 static int __net_init dccp_v4_init_net(struct net *net)
1016 {
1017         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1018
1019         if (dccp_hashinfo.bhash == NULL)
1020                 return -ESOCKTNOSUPPORT;
1021
1022         return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET,
1023                                     SOCK_DCCP, IPPROTO_DCCP, net);
1024 }
1025
1026 static void __net_exit dccp_v4_exit_net(struct net *net)
1027 {
1028         struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1029
1030         inet_ctl_sock_destroy(pn->v4_ctl_sk);
1031 }
1032
1033 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1034 {
1035         inet_twsk_purge(&dccp_hashinfo, AF_INET);
1036 }
1037
1038 static struct pernet_operations dccp_v4_ops = {
1039         .init   = dccp_v4_init_net,
1040         .exit   = dccp_v4_exit_net,
1041         .exit_batch = dccp_v4_exit_batch,
1042         .id     = &dccp_v4_pernet_id,
1043         .size   = sizeof(struct dccp_v4_pernet),
1044 };
1045
1046 static int __init dccp_v4_init(void)
1047 {
1048         int err = proto_register(&dccp_v4_prot, 1);
1049
1050         if (err)
1051                 goto out;
1052
1053         inet_register_protosw(&dccp_v4_protosw);
1054
1055         err = register_pernet_subsys(&dccp_v4_ops);
1056         if (err)
1057                 goto out_destroy_ctl_sock;
1058
1059         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1060         if (err)
1061                 goto out_proto_unregister;
1062
1063 out:
1064         return err;
1065 out_proto_unregister:
1066         unregister_pernet_subsys(&dccp_v4_ops);
1067 out_destroy_ctl_sock:
1068         inet_unregister_protosw(&dccp_v4_protosw);
1069         proto_unregister(&dccp_v4_prot);
1070         goto out;
1071 }
1072
1073 static void __exit dccp_v4_exit(void)
1074 {
1075         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1076         unregister_pernet_subsys(&dccp_v4_ops);
1077         inet_unregister_protosw(&dccp_v4_protosw);
1078         proto_unregister(&dccp_v4_prot);
1079 }
1080
1081 module_init(dccp_v4_init);
1082 module_exit(dccp_v4_exit);
1083
1084 /*
1085  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1086  * values directly, Also cover the case where the protocol is not specified,
1087  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1088  */
1089 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1090 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1091 MODULE_LICENSE("GPL");
1092 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1093 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");