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