net/l2tp/l2tp_ip6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * L2TPv3 IP encapsulation support for IPv6
   4  *
   5  * Copyright (c) 2012 Katalix Systems Ltd
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/icmp.h>
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/random.h>
  14 #include <linux/socket.h>
  15 #include <linux/l2tp.h>
  16 #include <linux/in.h>
  17 #include <linux/in6.h>
  18 #include <net/sock.h>
  19 #include <net/ip.h>
  20 #include <net/icmp.h>
  21 #include <net/udp.h>
  22 #include <net/inet_common.h>
  23 #include <net/tcp_states.h>
  24 #include <net/protocol.h>
  25 #include <net/xfrm.h>
  26
  27 #include <net/transp_v6.h>
  28 #include <net/addrconf.h>
  29 #include <net/ip6_route.h>
  30
  31 #include "l2tp_core.h"
  32
  33 struct l2tp_ip6_sock {
  34         /* inet_sock has to be the first member of l2tp_ip6_sock */
  35         struct inet_sock        inet;
  36
  37         u32                     conn_id;
  38         u32                     peer_conn_id;
  39
  40         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
  41            inet6_sk_generic */
  42         struct ipv6_pinfo       inet6;
  43 };
  44
  45 static DEFINE_RWLOCK(l2tp_ip6_lock);
  46 static struct hlist_head l2tp_ip6_table;
  47 static struct hlist_head l2tp_ip6_bind_table;
  48
  49 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
  50 {
  51         return (struct l2tp_ip6_sock *)sk;
  52 }
  53
  54 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
  55                                            const struct in6_addr *laddr,
  56                                            const struct in6_addr *raddr,
  57                                            int dif, u32 tunnel_id)
  58 {
  59         struct sock *sk;
  60
  61         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  62                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
  63                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
  64                 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  65
  66                 if (!net_eq(sock_net(sk), net))
  67                         continue;
  68
  69                 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
  70                         continue;
  71
  72                 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
  73                     !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
  74                         continue;
  75
  76                 if (!ipv6_addr_any(sk_raddr) && raddr &&
  77                     !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
  78                         continue;
  79
  80                 if (l2tp->conn_id != tunnel_id)
  81                         continue;
  82
  83                 goto found;
  84         }
  85
  86         sk = NULL;
  87 found:
  88         return sk;
  89 }
  90
  91 /* When processing receive frames, there are two cases to
  92  * consider. Data frames consist of a non-zero session-id and an
  93  * optional cookie. Control frames consist of a regular L2TP header
  94  * preceded by 32-bits of zeros.
  95  *
  96  * L2TPv3 Session Header Over IP
  97  *
  98  *  0                   1                   2                   3
  99  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 100  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 101  * |                           Session ID                          |
 102  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 103  * |               Cookie (optional, maximum 64 bits)...
 104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 105  *                                                                 |
 106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 107  *
 108  * L2TPv3 Control Message Header Over IP
 109  *
 110  *  0                   1                   2                   3
 111  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 112  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 113  * |                      (32 bits of zeros)                       |
 114  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 115  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 117  * |                     Control Connection ID                     |
 118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 119  * |               Ns              |               Nr              |
 120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 121  *
 122  * All control frames are passed to userspace.
 123  */
 124 static int l2tp_ip6_recv(struct sk_buff *skb)
 125 {
 126         struct net *net = dev_net(skb->dev);
 127         struct sock *sk;
 128         u32 session_id;
 129         u32 tunnel_id;
 130         unsigned char *ptr, *optr;
 131         struct l2tp_session *session;
 132         struct l2tp_tunnel *tunnel = NULL;
 133         struct ipv6hdr *iph;
 134         int length;
 135
 136         if (!pskb_may_pull(skb, 4))
 137                 goto discard;
 138
 139         /* Point to L2TP header */
 140         optr = ptr = skb->data;
 141         session_id = ntohl(*((__be32 *) ptr));
 142         ptr += 4;
 143
 144         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 145          * the session_id. If it is 0, the packet is a L2TP control
 146          * frame and the session_id value can be discarded.
 147          */
 148         if (session_id == 0) {
 149                 __skb_pull(skb, 4);
 150                 goto pass_up;
 151         }
 152
 153         /* Ok, this is a data packet. Lookup the session. */
 154         session = l2tp_session_get(net, session_id);
 155         if (!session)
 156                 goto discard;
 157
 158         tunnel = session->tunnel;
 159         if (!tunnel)
 160                 goto discard_sess;
 161
 162         /* Trace packet contents, if enabled */
 163         if (tunnel->debug & L2TP_MSG_DATA) {
 164                 length = min(32u, skb->len);
 165                 if (!pskb_may_pull(skb, length))
 166                         goto discard_sess;
 167
 168                 /* Point to L2TP header */
 169                 optr = ptr = skb->data;
 170                 ptr += 4;
 171                 pr_debug("%s: ip recv\n", tunnel->name);
 172                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 173         }
 174
 175         if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 176                 goto discard_sess;
 177
 178         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
 179         l2tp_session_dec_refcount(session);
 180
 181         return 0;
 182
 183 pass_up:
 184         /* Get the tunnel_id from the L2TP header */
 185         if (!pskb_may_pull(skb, 12))
 186                 goto discard;
 187
 188         if ((skb->data[0] & 0xc0) != 0xc0)
 189                 goto discard;
 190
 191         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 192         iph = ipv6_hdr(skb);
 193
 194         read_lock_bh(&l2tp_ip6_lock);
 195         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 196                                     inet6_iif(skb), tunnel_id);
 197         if (!sk) {
 198                 read_unlock_bh(&l2tp_ip6_lock);
 199                 goto discard;
 200         }
 201         sock_hold(sk);
 202         read_unlock_bh(&l2tp_ip6_lock);
 203
 204         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 205                 goto discard_put;
 206
 207         nf_reset_ct(skb);
 208
 209         return sk_receive_skb(sk, skb, 1);
 210
 211 discard_sess:
 212         l2tp_session_dec_refcount(session);
 213         goto discard;
 214
 215 discard_put:
 216         sock_put(sk);
 217
 218 discard:
 219         kfree_skb(skb);
 220         return 0;
 221 }
 222
 223 static int l2tp_ip6_hash(struct sock *sk)
 224 {
 225         if (sk_unhashed(sk)) {
 226                 write_lock_bh(&l2tp_ip6_lock);
 227                 sk_add_node(sk, &l2tp_ip6_table);
 228                 write_unlock_bh(&l2tp_ip6_lock);
 229         }
 230         return 0;
 231 }
 232
 233 static void l2tp_ip6_unhash(struct sock *sk)
 234 {
 235         if (sk_unhashed(sk))
 236                 return;
 237         write_lock_bh(&l2tp_ip6_lock);
 238         sk_del_node_init(sk);
 239         write_unlock_bh(&l2tp_ip6_lock);
 240 }
 241
 242 static int l2tp_ip6_open(struct sock *sk)
 243 {
 244         /* Prevent autobind. We don't have ports. */
 245         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 246
 247         l2tp_ip6_hash(sk);
 248         return 0;
 249 }
 250
 251 static void l2tp_ip6_close(struct sock *sk, long timeout)
 252 {
 253         write_lock_bh(&l2tp_ip6_lock);
 254         hlist_del_init(&sk->sk_bind_node);
 255         sk_del_node_init(sk);
 256         write_unlock_bh(&l2tp_ip6_lock);
 257
 258         sk_common_release(sk);
 259 }
 260
 261 static void l2tp_ip6_destroy_sock(struct sock *sk)
 262 {
 263         struct l2tp_tunnel *tunnel = sk->sk_user_data;
 264
 265         lock_sock(sk);
 266         ip6_flush_pending_frames(sk);
 267         release_sock(sk);
 268
 269         if (tunnel)
 270                 l2tp_tunnel_delete(tunnel);
 271
 272         inet6_destroy_sock(sk);
 273 }
 274
 275 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 276 {
 277         struct inet_sock *inet = inet_sk(sk);
 278         struct ipv6_pinfo *np = inet6_sk(sk);
 279         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 280         struct net *net = sock_net(sk);
 281         __be32 v4addr = 0;
 282         int bound_dev_if;
 283         int addr_type;
 284         int err;
 285
 286         if (addr->l2tp_family != AF_INET6)
 287                 return -EINVAL;
 288         if (addr_len < sizeof(*addr))
 289                 return -EINVAL;
 290
 291         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 292
 293         /* l2tp_ip6 sockets are IPv6 only */
 294         if (addr_type == IPV6_ADDR_MAPPED)
 295                 return -EADDRNOTAVAIL;
 296
 297         /* L2TP is point-point, not multicast */
 298         if (addr_type & IPV6_ADDR_MULTICAST)
 299                 return -EADDRNOTAVAIL;
 300
 301         lock_sock(sk);
 302
 303         err = -EINVAL;
 304         if (!sock_flag(sk, SOCK_ZAPPED))
 305                 goto out_unlock;
 306
 307         if (sk->sk_state != TCP_CLOSE)
 308                 goto out_unlock;
 309
 310         bound_dev_if = sk->sk_bound_dev_if;
 311
 312         /* Check if the address belongs to the host. */
 313         rcu_read_lock();
 314         if (addr_type != IPV6_ADDR_ANY) {
 315                 struct net_device *dev = NULL;
 316
 317                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 318                         if (addr->l2tp_scope_id)
 319                                 bound_dev_if = addr->l2tp_scope_id;
 320
 321                         /* Binding to link-local address requires an
 322                          * interface.
 323                          */
 324                         if (!bound_dev_if)
 325                                 goto out_unlock_rcu;
 326
 327                         err = -ENODEV;
 328                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
 329                         if (!dev)
 330                                 goto out_unlock_rcu;
 331                 }
 332
 333                 /* ipv4 addr of the socket is invalid.  Only the
 334                  * unspecified and mapped address have a v4 equivalent.
 335                  */
 336                 v4addr = LOOPBACK4_IPV6;
 337                 err = -EADDRNOTAVAIL;
 338                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 339                         goto out_unlock_rcu;
 340         }
 341         rcu_read_unlock();
 342
 343         write_lock_bh(&l2tp_ip6_lock);
 344         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 345                                    addr->l2tp_conn_id)) {
 346                 write_unlock_bh(&l2tp_ip6_lock);
 347                 err = -EADDRINUSE;
 348                 goto out_unlock;
 349         }
 350
 351         inet->inet_saddr = v4addr;
 352         inet->inet_rcv_saddr = v4addr;
 353         sk->sk_bound_dev_if = bound_dev_if;
 354         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 355         np->saddr = addr->l2tp_addr;
 356
 357         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 358
 359         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 360         sk_del_node_init(sk);
 361         write_unlock_bh(&l2tp_ip6_lock);
 362
 363         sock_reset_flag(sk, SOCK_ZAPPED);
 364         release_sock(sk);
 365         return 0;
 366
 367 out_unlock_rcu:
 368         rcu_read_unlock();
 369 out_unlock:
 370         release_sock(sk);
 371
 372         return err;
 373 }
 374
 375 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 376                             int addr_len)
 377 {
 378         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 379         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 380         struct in6_addr *daddr;
 381         int     addr_type;
 382         int rc;
 383
 384         if (addr_len < sizeof(*lsa))
 385                 return -EINVAL;
 386
 387         if (usin->sin6_family != AF_INET6)
 388                 return -EINVAL;
 389
 390         addr_type = ipv6_addr_type(&usin->sin6_addr);
 391         if (addr_type & IPV6_ADDR_MULTICAST)
 392                 return -EINVAL;
 393
 394         if (addr_type & IPV6_ADDR_MAPPED) {
 395                 daddr = &usin->sin6_addr;
 396                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 397                         return -EINVAL;
 398         }
 399
 400         lock_sock(sk);
 401
 402          /* Must bind first - autobinding does not work */
 403         if (sock_flag(sk, SOCK_ZAPPED)) {
 404                 rc = -EINVAL;
 405                 goto out_sk;
 406         }
 407
 408         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
 409         if (rc < 0)
 410                 goto out_sk;
 411
 412         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 413
 414         write_lock_bh(&l2tp_ip6_lock);
 415         hlist_del_init(&sk->sk_bind_node);
 416         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 417         write_unlock_bh(&l2tp_ip6_lock);
 418
 419 out_sk:
 420         release_sock(sk);
 421
 422         return rc;
 423 }
 424
 425 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 426 {
 427         if (sock_flag(sk, SOCK_ZAPPED))
 428                 return 0;
 429
 430         return __udp_disconnect(sk, flags);
 431 }
 432
 433 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 434                             int peer)
 435 {
 436         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 437         struct sock *sk = sock->sk;
 438         struct ipv6_pinfo *np = inet6_sk(sk);
 439         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 440
 441         lsa->l2tp_family = AF_INET6;
 442         lsa->l2tp_flowinfo = 0;
 443         lsa->l2tp_scope_id = 0;
 444         lsa->l2tp_unused = 0;
 445         if (peer) {
 446                 if (!lsk->peer_conn_id)
 447                         return -ENOTCONN;
 448                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 449                 lsa->l2tp_addr = sk->sk_v6_daddr;
 450                 if (np->sndflow)
 451                         lsa->l2tp_flowinfo = np->flow_label;
 452         } else {
 453                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 454                         lsa->l2tp_addr = np->saddr;
 455                 else
 456                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 457
 458                 lsa->l2tp_conn_id = lsk->conn_id;
 459         }
 460         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 461                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 462         return sizeof(*lsa);
 463 }
 464
 465 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 466 {
 467         int rc;
 468
 469         /* Charge it to the socket, dropping if the queue is full. */
 470         rc = sock_queue_rcv_skb(sk, skb);
 471         if (rc < 0)
 472                 goto drop;
 473
 474         return 0;
 475
 476 drop:
 477         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 478         kfree_skb(skb);
 479         return -1;
 480 }
 481
 482 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 483 {
 484         struct sk_buff *skb;
 485         __be32 *transhdr = NULL;
 486         int err = 0;
 487
 488         skb = skb_peek(&sk->sk_write_queue);
 489         if (skb == NULL)
 490                 goto out;
 491
 492         transhdr = (__be32 *)skb_transport_header(skb);
 493         *transhdr = 0;
 494
 495         err = ip6_push_pending_frames(sk);
 496
 497 out:
 498         return err;
 499 }
 500
 501 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 502  * control frames.
 503  */
 504 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 505 {
 506         struct ipv6_txoptions opt_space;
 507         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 508         struct in6_addr *daddr, *final_p, final;
 509         struct ipv6_pinfo *np = inet6_sk(sk);
 510         struct ipv6_txoptions *opt_to_free = NULL;
 511         struct ipv6_txoptions *opt = NULL;
 512         struct ip6_flowlabel *flowlabel = NULL;
 513         struct dst_entry *dst = NULL;
 514         struct flowi6 fl6;
 515         struct ipcm6_cookie ipc6;
 516         int addr_len = msg->msg_namelen;
 517         int transhdrlen = 4; /* zero session-id */
 518         int ulen = len + transhdrlen;
 519         int err;
 520
 521         /* Rough check on arithmetic overflow,
 522            better check is made in ip6_append_data().
 523          */
 524         if (len > INT_MAX)
 525                 return -EMSGSIZE;
 526
 527         /* Mirror BSD error message compatibility */
 528         if (msg->msg_flags & MSG_OOB)
 529                 return -EOPNOTSUPP;
 530
 531         /*
 532          *      Get and verify the address.
 533          */
 534         memset(&fl6, 0, sizeof(fl6));
 535
 536         fl6.flowi6_mark = sk->sk_mark;
 537         fl6.flowi6_uid = sk->sk_uid;
 538
 539         ipcm6_init(&ipc6);
 540
 541         if (lsa) {
 542                 if (addr_len < SIN6_LEN_RFC2133)
 543                         return -EINVAL;
 544
 545                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 546                         return -EAFNOSUPPORT;
 547
 548                 daddr = &lsa->l2tp_addr;
 549                 if (np->sndflow) {
 550                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 551                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 552                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 553                                 if (IS_ERR(flowlabel))
 554                                         return -EINVAL;
 555                         }
 556                 }
 557
 558                 /*
 559                  * Otherwise it will be difficult to maintain
 560                  * sk->sk_dst_cache.
 561                  */
 562                 if (sk->sk_state == TCP_ESTABLISHED &&
 563                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 564                         daddr = &sk->sk_v6_daddr;
 565
 566                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 567                     lsa->l2tp_scope_id &&
 568                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 569                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 570         } else {
 571                 if (sk->sk_state != TCP_ESTABLISHED)
 572                         return -EDESTADDRREQ;
 573
 574                 daddr = &sk->sk_v6_daddr;
 575                 fl6.flowlabel = np->flow_label;
 576         }
 577
 578         if (fl6.flowi6_oif == 0)
 579                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 580
 581         if (msg->msg_controllen) {
 582                 opt = &opt_space;
 583                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 584                 opt->tot_len = sizeof(struct ipv6_txoptions);
 585                 ipc6.opt = opt;
 586
 587                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
 588                 if (err < 0) {
 589                         fl6_sock_release(flowlabel);
 590                         return err;
 591                 }
 592                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 593                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 594                         if (IS_ERR(flowlabel))
 595                                 return -EINVAL;
 596                 }
 597                 if (!(opt->opt_nflen|opt->opt_flen))
 598                         opt = NULL;
 599         }
 600
 601         if (!opt) {
 602                 opt = txopt_get(np);
 603                 opt_to_free = opt;
 604         }
 605         if (flowlabel)
 606                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 607         opt = ipv6_fixup_options(&opt_space, opt);
 608         ipc6.opt = opt;
 609
 610         fl6.flowi6_proto = sk->sk_protocol;
 611         if (!ipv6_addr_any(daddr))
 612                 fl6.daddr = *daddr;
 613         else
 614                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 615         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 616                 fl6.saddr = np->saddr;
 617
 618         final_p = fl6_update_dst(&fl6, opt, &final);
 619
 620         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 621                 fl6.flowi6_oif = np->mcast_oif;
 622         else if (!fl6.flowi6_oif)
 623                 fl6.flowi6_oif = np->ucast_oif;
 624
 625         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 626
 627         if (ipc6.tclass < 0)
 628                 ipc6.tclass = np->tclass;
 629
 630         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 631
 632         dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
 633         if (IS_ERR(dst)) {
 634                 err = PTR_ERR(dst);
 635                 goto out;
 636         }
 637
 638         if (ipc6.hlimit < 0)
 639                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 640
 641         if (ipc6.dontfrag < 0)
 642                 ipc6.dontfrag = np->dontfrag;
 643
 644         if (msg->msg_flags & MSG_CONFIRM)
 645                 goto do_confirm;
 646
 647 back_from_confirm:
 648         lock_sock(sk);
 649         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 650                               ulen, transhdrlen, &ipc6,
 651                               &fl6, (struct rt6_info *)dst,
 652                               msg->msg_flags);
 653         if (err)
 654                 ip6_flush_pending_frames(sk);
 655         else if (!(msg->msg_flags & MSG_MORE))
 656                 err = l2tp_ip6_push_pending_frames(sk);
 657         release_sock(sk);
 658 done:
 659         dst_release(dst);
 660 out:
 661         fl6_sock_release(flowlabel);
 662         txopt_put(opt_to_free);
 663
 664         return err < 0 ? err : len;
 665
 666 do_confirm:
 667         if (msg->msg_flags & MSG_PROBE)
 668                 dst_confirm_neigh(dst, &fl6.daddr);
 669         if (!(msg->msg_flags & MSG_PROBE) || len)
 670                 goto back_from_confirm;
 671         err = 0;
 672         goto done;
 673 }
 674
 675 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 676                             int noblock, int flags, int *addr_len)
 677 {
 678         struct ipv6_pinfo *np = inet6_sk(sk);
 679         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 680         size_t copied = 0;
 681         int err = -EOPNOTSUPP;
 682         struct sk_buff *skb;
 683
 684         if (flags & MSG_OOB)
 685                 goto out;
 686
 687         if (flags & MSG_ERRQUEUE)
 688                 return ipv6_recv_error(sk, msg, len, addr_len);
 689
 690         skb = skb_recv_datagram(sk, flags, noblock, &err);
 691         if (!skb)
 692                 goto out;
 693
 694         copied = skb->len;
 695         if (len < copied) {
 696                 msg->msg_flags |= MSG_TRUNC;
 697                 copied = len;
 698         }
 699
 700         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 701         if (err)
 702                 goto done;
 703
 704         sock_recv_timestamp(msg, sk, skb);
 705
 706         /* Copy the address. */
 707         if (lsa) {
 708                 lsa->l2tp_family = AF_INET6;
 709                 lsa->l2tp_unused = 0;
 710                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 711                 lsa->l2tp_flowinfo = 0;
 712                 lsa->l2tp_scope_id = 0;
 713                 lsa->l2tp_conn_id = 0;
 714                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 715                         lsa->l2tp_scope_id = inet6_iif(skb);
 716                 *addr_len = sizeof(*lsa);
 717         }
 718
 719         if (np->rxopt.all)
 720                 ip6_datagram_recv_ctl(sk, msg, skb);
 721
 722         if (flags & MSG_TRUNC)
 723                 copied = skb->len;
 724 done:
 725         skb_free_datagram(sk, skb);
 726 out:
 727         return err ? err : copied;
 728 }
 729
 730 static struct proto l2tp_ip6_prot = {
 731         .name              = "L2TP/IPv6",
 732         .owner             = THIS_MODULE,
 733         .init              = l2tp_ip6_open,
 734         .close             = l2tp_ip6_close,
 735         .bind              = l2tp_ip6_bind,
 736         .connect           = l2tp_ip6_connect,
 737         .disconnect        = l2tp_ip6_disconnect,
 738         .ioctl             = l2tp_ioctl,
 739         .destroy           = l2tp_ip6_destroy_sock,
 740         .setsockopt        = ipv6_setsockopt,
 741         .getsockopt        = ipv6_getsockopt,
 742         .sendmsg           = l2tp_ip6_sendmsg,
 743         .recvmsg           = l2tp_ip6_recvmsg,
 744         .backlog_rcv       = l2tp_ip6_backlog_recv,
 745         .hash              = l2tp_ip6_hash,
 746         .unhash            = l2tp_ip6_unhash,
 747         .obj_size          = sizeof(struct l2tp_ip6_sock),
 748 #ifdef CONFIG_COMPAT
 749         .compat_setsockopt = compat_ipv6_setsockopt,
 750         .compat_getsockopt = compat_ipv6_getsockopt,
 751 #endif
 752 };
 753
 754 static const struct proto_ops l2tp_ip6_ops = {
 755         .family            = PF_INET6,
 756         .owner             = THIS_MODULE,
 757         .release           = inet6_release,
 758         .bind              = inet6_bind,
 759         .connect           = inet_dgram_connect,
 760         .socketpair        = sock_no_socketpair,
 761         .accept            = sock_no_accept,
 762         .getname           = l2tp_ip6_getname,
 763         .poll              = datagram_poll,
 764         .ioctl             = inet6_ioctl,
 765         .gettstamp         = sock_gettstamp,
 766         .listen            = sock_no_listen,
 767         .shutdown          = inet_shutdown,
 768         .setsockopt        = sock_common_setsockopt,
 769         .getsockopt        = sock_common_getsockopt,
 770         .sendmsg           = inet_sendmsg,
 771         .recvmsg           = sock_common_recvmsg,
 772         .mmap              = sock_no_mmap,
 773         .sendpage          = sock_no_sendpage,
 774 #ifdef CONFIG_COMPAT
 775         .compat_setsockopt = compat_sock_common_setsockopt,
 776         .compat_getsockopt = compat_sock_common_getsockopt,
 777 #endif
 778 };
 779
 780 static struct inet_protosw l2tp_ip6_protosw = {
 781         .type           = SOCK_DGRAM,
 782         .protocol       = IPPROTO_L2TP,
 783         .prot           = &l2tp_ip6_prot,
 784         .ops            = &l2tp_ip6_ops,
 785 };
 786
 787 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 788         .handler        = l2tp_ip6_recv,
 789 };
 790
 791 static int __init l2tp_ip6_init(void)
 792 {
 793         int err;
 794
 795         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 796
 797         err = proto_register(&l2tp_ip6_prot, 1);
 798         if (err != 0)
 799                 goto out;
 800
 801         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 802         if (err)
 803                 goto out1;
 804
 805         inet6_register_protosw(&l2tp_ip6_protosw);
 806         return 0;
 807
 808 out1:
 809         proto_unregister(&l2tp_ip6_prot);
 810 out:
 811         return err;
 812 }
 813
 814 static void __exit l2tp_ip6_exit(void)
 815 {
 816         inet6_unregister_protosw(&l2tp_ip6_protosw);
 817         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 818         proto_unregister(&l2tp_ip6_prot);
 819 }
 820
 821 module_init(l2tp_ip6_init);
 822 module_exit(l2tp_ip6_exit);
 823
 824 MODULE_LICENSE("GPL");
 825 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 826 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 827 MODULE_VERSION("1.0");
 828
 829 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 830  * enums
 831  */
 832 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 833 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);