net/l2tp/l2tp_ip6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* L2TPv3 IP encapsulation support for IPv6
   3  *
   4  * Copyright (c) 2012 Katalix Systems Ltd
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9 #include <linux/icmp.h>
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/random.h>
  13 #include <linux/socket.h>
  14 #include <linux/l2tp.h>
  15 #include <linux/in.h>
  16 #include <linux/in6.h>
  17 #include <net/sock.h>
  18 #include <net/ip.h>
  19 #include <net/icmp.h>
  20 #include <net/udp.h>
  21 #include <net/inet_common.h>
  22 #include <net/tcp_states.h>
  23 #include <net/protocol.h>
  24 #include <net/xfrm.h>
  25
  26 #include <net/transp_v6.h>
  27 #include <net/addrconf.h>
  28 #include <net/ip6_route.h>
  29
  30 #include "l2tp_core.h"
  31
  32 struct l2tp_ip6_sock {
  33         /* inet_sock has to be the first member of l2tp_ip6_sock */
  34         struct inet_sock        inet;
  35
  36         u32                     conn_id;
  37         u32                     peer_conn_id;
  38
  39         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
  40          * inet6_sk_generic
  41          */
  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
 135         if (!pskb_may_pull(skb, 4))
 136                 goto discard;
 137
 138         /* Point to L2TP header */
 139         optr = skb->data;
 140         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         if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 163                 goto discard_sess;
 164
 165         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
 166         l2tp_session_dec_refcount(session);
 167
 168         return 0;
 169
 170 pass_up:
 171         /* Get the tunnel_id from the L2TP header */
 172         if (!pskb_may_pull(skb, 12))
 173                 goto discard;
 174
 175         if ((skb->data[0] & 0xc0) != 0xc0)
 176                 goto discard;
 177
 178         tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
 179         iph = ipv6_hdr(skb);
 180
 181         read_lock_bh(&l2tp_ip6_lock);
 182         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 183                                     inet6_iif(skb), tunnel_id);
 184         if (!sk) {
 185                 read_unlock_bh(&l2tp_ip6_lock);
 186                 goto discard;
 187         }
 188         sock_hold(sk);
 189         read_unlock_bh(&l2tp_ip6_lock);
 190
 191         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 192                 goto discard_put;
 193
 194         nf_reset_ct(skb);
 195
 196         return sk_receive_skb(sk, skb, 1);
 197
 198 discard_sess:
 199         l2tp_session_dec_refcount(session);
 200         goto discard;
 201
 202 discard_put:
 203         sock_put(sk);
 204
 205 discard:
 206         kfree_skb(skb);
 207         return 0;
 208 }
 209
 210 static int l2tp_ip6_hash(struct sock *sk)
 211 {
 212         if (sk_unhashed(sk)) {
 213                 write_lock_bh(&l2tp_ip6_lock);
 214                 sk_add_node(sk, &l2tp_ip6_table);
 215                 write_unlock_bh(&l2tp_ip6_lock);
 216         }
 217         return 0;
 218 }
 219
 220 static void l2tp_ip6_unhash(struct sock *sk)
 221 {
 222         if (sk_unhashed(sk))
 223                 return;
 224         write_lock_bh(&l2tp_ip6_lock);
 225         sk_del_node_init(sk);
 226         write_unlock_bh(&l2tp_ip6_lock);
 227 }
 228
 229 static int l2tp_ip6_open(struct sock *sk)
 230 {
 231         /* Prevent autobind. We don't have ports. */
 232         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 233
 234         l2tp_ip6_hash(sk);
 235         return 0;
 236 }
 237
 238 static void l2tp_ip6_close(struct sock *sk, long timeout)
 239 {
 240         write_lock_bh(&l2tp_ip6_lock);
 241         hlist_del_init(&sk->sk_bind_node);
 242         sk_del_node_init(sk);
 243         write_unlock_bh(&l2tp_ip6_lock);
 244
 245         sk_common_release(sk);
 246 }
 247
 248 static void l2tp_ip6_destroy_sock(struct sock *sk)
 249 {
 250         struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
 251
 252         lock_sock(sk);
 253         ip6_flush_pending_frames(sk);
 254         release_sock(sk);
 255
 256         if (tunnel)
 257                 l2tp_tunnel_delete(tunnel);
 258
 259         inet6_destroy_sock(sk);
 260 }
 261
 262 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 263 {
 264         struct inet_sock *inet = inet_sk(sk);
 265         struct ipv6_pinfo *np = inet6_sk(sk);
 266         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
 267         struct net *net = sock_net(sk);
 268         __be32 v4addr = 0;
 269         int bound_dev_if;
 270         int addr_type;
 271         int err;
 272
 273         if (addr->l2tp_family != AF_INET6)
 274                 return -EINVAL;
 275         if (addr_len < sizeof(*addr))
 276                 return -EINVAL;
 277
 278         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 279
 280         /* l2tp_ip6 sockets are IPv6 only */
 281         if (addr_type == IPV6_ADDR_MAPPED)
 282                 return -EADDRNOTAVAIL;
 283
 284         /* L2TP is point-point, not multicast */
 285         if (addr_type & IPV6_ADDR_MULTICAST)
 286                 return -EADDRNOTAVAIL;
 287
 288         lock_sock(sk);
 289
 290         err = -EINVAL;
 291         if (!sock_flag(sk, SOCK_ZAPPED))
 292                 goto out_unlock;
 293
 294         if (sk->sk_state != TCP_CLOSE)
 295                 goto out_unlock;
 296
 297         bound_dev_if = sk->sk_bound_dev_if;
 298
 299         /* Check if the address belongs to the host. */
 300         rcu_read_lock();
 301         if (addr_type != IPV6_ADDR_ANY) {
 302                 struct net_device *dev = NULL;
 303
 304                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 305                         if (addr->l2tp_scope_id)
 306                                 bound_dev_if = addr->l2tp_scope_id;
 307
 308                         /* Binding to link-local address requires an
 309                          * interface.
 310                          */
 311                         if (!bound_dev_if)
 312                                 goto out_unlock_rcu;
 313
 314                         err = -ENODEV;
 315                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
 316                         if (!dev)
 317                                 goto out_unlock_rcu;
 318                 }
 319
 320                 /* ipv4 addr of the socket is invalid.  Only the
 321                  * unspecified and mapped address have a v4 equivalent.
 322                  */
 323                 v4addr = LOOPBACK4_IPV6;
 324                 err = -EADDRNOTAVAIL;
 325                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 326                         goto out_unlock_rcu;
 327         }
 328         rcu_read_unlock();
 329
 330         write_lock_bh(&l2tp_ip6_lock);
 331         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 332                                    addr->l2tp_conn_id)) {
 333                 write_unlock_bh(&l2tp_ip6_lock);
 334                 err = -EADDRINUSE;
 335                 goto out_unlock;
 336         }
 337
 338         inet->inet_saddr = v4addr;
 339         inet->inet_rcv_saddr = v4addr;
 340         sk->sk_bound_dev_if = bound_dev_if;
 341         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 342         np->saddr = addr->l2tp_addr;
 343
 344         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 345
 346         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 347         sk_del_node_init(sk);
 348         write_unlock_bh(&l2tp_ip6_lock);
 349
 350         sock_reset_flag(sk, SOCK_ZAPPED);
 351         release_sock(sk);
 352         return 0;
 353
 354 out_unlock_rcu:
 355         rcu_read_unlock();
 356 out_unlock:
 357         release_sock(sk);
 358
 359         return err;
 360 }
 361
 362 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 363                             int addr_len)
 364 {
 365         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 366         struct sockaddr_in6     *usin = (struct sockaddr_in6 *)uaddr;
 367         struct in6_addr *daddr;
 368         int     addr_type;
 369         int rc;
 370
 371         if (addr_len < sizeof(*lsa))
 372                 return -EINVAL;
 373
 374         if (usin->sin6_family != AF_INET6)
 375                 return -EINVAL;
 376
 377         addr_type = ipv6_addr_type(&usin->sin6_addr);
 378         if (addr_type & IPV6_ADDR_MULTICAST)
 379                 return -EINVAL;
 380
 381         if (addr_type & IPV6_ADDR_MAPPED) {
 382                 daddr = &usin->sin6_addr;
 383                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 384                         return -EINVAL;
 385         }
 386
 387         lock_sock(sk);
 388
 389          /* Must bind first - autobinding does not work */
 390         if (sock_flag(sk, SOCK_ZAPPED)) {
 391                 rc = -EINVAL;
 392                 goto out_sk;
 393         }
 394
 395         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
 396         if (rc < 0)
 397                 goto out_sk;
 398
 399         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 400
 401         write_lock_bh(&l2tp_ip6_lock);
 402         hlist_del_init(&sk->sk_bind_node);
 403         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 404         write_unlock_bh(&l2tp_ip6_lock);
 405
 406 out_sk:
 407         release_sock(sk);
 408
 409         return rc;
 410 }
 411
 412 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 413 {
 414         if (sock_flag(sk, SOCK_ZAPPED))
 415                 return 0;
 416
 417         return __udp_disconnect(sk, flags);
 418 }
 419
 420 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 421                             int peer)
 422 {
 423         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 424         struct sock *sk = sock->sk;
 425         struct ipv6_pinfo *np = inet6_sk(sk);
 426         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 427
 428         lsa->l2tp_family = AF_INET6;
 429         lsa->l2tp_flowinfo = 0;
 430         lsa->l2tp_scope_id = 0;
 431         lsa->l2tp_unused = 0;
 432         if (peer) {
 433                 if (!lsk->peer_conn_id)
 434                         return -ENOTCONN;
 435                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 436                 lsa->l2tp_addr = sk->sk_v6_daddr;
 437                 if (np->sndflow)
 438                         lsa->l2tp_flowinfo = np->flow_label;
 439         } else {
 440                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 441                         lsa->l2tp_addr = np->saddr;
 442                 else
 443                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 444
 445                 lsa->l2tp_conn_id = lsk->conn_id;
 446         }
 447         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 448                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 449         return sizeof(*lsa);
 450 }
 451
 452 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 453 {
 454         int rc;
 455
 456         /* Charge it to the socket, dropping if the queue is full. */
 457         rc = sock_queue_rcv_skb(sk, skb);
 458         if (rc < 0)
 459                 goto drop;
 460
 461         return 0;
 462
 463 drop:
 464         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 465         kfree_skb(skb);
 466         return -1;
 467 }
 468
 469 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 470 {
 471         struct sk_buff *skb;
 472         __be32 *transhdr = NULL;
 473         int err = 0;
 474
 475         skb = skb_peek(&sk->sk_write_queue);
 476         if (!skb)
 477                 goto out;
 478
 479         transhdr = (__be32 *)skb_transport_header(skb);
 480         *transhdr = 0;
 481
 482         err = ip6_push_pending_frames(sk);
 483
 484 out:
 485         return err;
 486 }
 487
 488 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 489  * control frames.
 490  */
 491 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 492 {
 493         struct ipv6_txoptions opt_space;
 494         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 495         struct in6_addr *daddr, *final_p, final;
 496         struct ipv6_pinfo *np = inet6_sk(sk);
 497         struct ipv6_txoptions *opt_to_free = NULL;
 498         struct ipv6_txoptions *opt = NULL;
 499         struct ip6_flowlabel *flowlabel = NULL;
 500         struct dst_entry *dst = NULL;
 501         struct flowi6 fl6;
 502         struct ipcm6_cookie ipc6;
 503         int addr_len = msg->msg_namelen;
 504         int transhdrlen = 4; /* zero session-id */
 505         int ulen = len + transhdrlen;
 506         int err;
 507
 508         /* Rough check on arithmetic overflow,
 509          * better check is made in ip6_append_data().
 510          */
 511         if (len > INT_MAX)
 512                 return -EMSGSIZE;
 513
 514         /* Mirror BSD error message compatibility */
 515         if (msg->msg_flags & MSG_OOB)
 516                 return -EOPNOTSUPP;
 517
 518         /* Get and verify the address */
 519         memset(&fl6, 0, sizeof(fl6));
 520
 521         fl6.flowi6_mark = sk->sk_mark;
 522         fl6.flowi6_uid = sk->sk_uid;
 523
 524         ipcm6_init(&ipc6);
 525
 526         if (lsa) {
 527                 if (addr_len < SIN6_LEN_RFC2133)
 528                         return -EINVAL;
 529
 530                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 531                         return -EAFNOSUPPORT;
 532
 533                 daddr = &lsa->l2tp_addr;
 534                 if (np->sndflow) {
 535                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 536                         if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
 537                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 538                                 if (IS_ERR(flowlabel))
 539                                         return -EINVAL;
 540                         }
 541                 }
 542
 543                 /* Otherwise it will be difficult to maintain
 544                  * sk->sk_dst_cache.
 545                  */
 546                 if (sk->sk_state == TCP_ESTABLISHED &&
 547                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 548                         daddr = &sk->sk_v6_daddr;
 549
 550                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 551                     lsa->l2tp_scope_id &&
 552                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 553                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 554         } else {
 555                 if (sk->sk_state != TCP_ESTABLISHED)
 556                         return -EDESTADDRREQ;
 557
 558                 daddr = &sk->sk_v6_daddr;
 559                 fl6.flowlabel = np->flow_label;
 560         }
 561
 562         if (fl6.flowi6_oif == 0)
 563                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 564
 565         if (msg->msg_controllen) {
 566                 opt = &opt_space;
 567                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 568                 opt->tot_len = sizeof(struct ipv6_txoptions);
 569                 ipc6.opt = opt;
 570
 571                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
 572                 if (err < 0) {
 573                         fl6_sock_release(flowlabel);
 574                         return err;
 575                 }
 576                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 577                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 578                         if (IS_ERR(flowlabel))
 579                                 return -EINVAL;
 580                 }
 581                 if (!(opt->opt_nflen | opt->opt_flen))
 582                         opt = NULL;
 583         }
 584
 585         if (!opt) {
 586                 opt = txopt_get(np);
 587                 opt_to_free = opt;
 588         }
 589         if (flowlabel)
 590                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 591         opt = ipv6_fixup_options(&opt_space, opt);
 592         ipc6.opt = opt;
 593
 594         fl6.flowi6_proto = sk->sk_protocol;
 595         if (!ipv6_addr_any(daddr))
 596                 fl6.daddr = *daddr;
 597         else
 598                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 599         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 600                 fl6.saddr = np->saddr;
 601
 602         final_p = fl6_update_dst(&fl6, opt, &final);
 603
 604         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 605                 fl6.flowi6_oif = np->mcast_oif;
 606         else if (!fl6.flowi6_oif)
 607                 fl6.flowi6_oif = np->ucast_oif;
 608
 609         security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
 610
 611         if (ipc6.tclass < 0)
 612                 ipc6.tclass = np->tclass;
 613
 614         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 615
 616         dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
 617         if (IS_ERR(dst)) {
 618                 err = PTR_ERR(dst);
 619                 goto out;
 620         }
 621
 622         if (ipc6.hlimit < 0)
 623                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 624
 625         if (ipc6.dontfrag < 0)
 626                 ipc6.dontfrag = np->dontfrag;
 627
 628         if (msg->msg_flags & MSG_CONFIRM)
 629                 goto do_confirm;
 630
 631 back_from_confirm:
 632         lock_sock(sk);
 633         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 634                               ulen, transhdrlen, &ipc6,
 635                               &fl6, (struct rt6_info *)dst,
 636                               msg->msg_flags);
 637         if (err)
 638                 ip6_flush_pending_frames(sk);
 639         else if (!(msg->msg_flags & MSG_MORE))
 640                 err = l2tp_ip6_push_pending_frames(sk);
 641         release_sock(sk);
 642 done:
 643         dst_release(dst);
 644 out:
 645         fl6_sock_release(flowlabel);
 646         txopt_put(opt_to_free);
 647
 648         return err < 0 ? err : len;
 649
 650 do_confirm:
 651         if (msg->msg_flags & MSG_PROBE)
 652                 dst_confirm_neigh(dst, &fl6.daddr);
 653         if (!(msg->msg_flags & MSG_PROBE) || len)
 654                 goto back_from_confirm;
 655         err = 0;
 656         goto done;
 657 }
 658
 659 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 660                             int noblock, int flags, int *addr_len)
 661 {
 662         struct ipv6_pinfo *np = inet6_sk(sk);
 663         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 664         size_t copied = 0;
 665         int err = -EOPNOTSUPP;
 666         struct sk_buff *skb;
 667
 668         if (flags & MSG_OOB)
 669                 goto out;
 670
 671         if (flags & MSG_ERRQUEUE)
 672                 return ipv6_recv_error(sk, msg, len, addr_len);
 673
 674         skb = skb_recv_datagram(sk, flags, noblock, &err);
 675         if (!skb)
 676                 goto out;
 677
 678         copied = skb->len;
 679         if (len < copied) {
 680                 msg->msg_flags |= MSG_TRUNC;
 681                 copied = len;
 682         }
 683
 684         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 685         if (err)
 686                 goto done;
 687
 688         sock_recv_timestamp(msg, sk, skb);
 689
 690         /* Copy the address. */
 691         if (lsa) {
 692                 lsa->l2tp_family = AF_INET6;
 693                 lsa->l2tp_unused = 0;
 694                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 695                 lsa->l2tp_flowinfo = 0;
 696                 lsa->l2tp_scope_id = 0;
 697                 lsa->l2tp_conn_id = 0;
 698                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 699                         lsa->l2tp_scope_id = inet6_iif(skb);
 700                 *addr_len = sizeof(*lsa);
 701         }
 702
 703         if (np->rxopt.all)
 704                 ip6_datagram_recv_ctl(sk, msg, skb);
 705
 706         if (flags & MSG_TRUNC)
 707                 copied = skb->len;
 708 done:
 709         skb_free_datagram(sk, skb);
 710 out:
 711         return err ? err : copied;
 712 }
 713
 714 static struct proto l2tp_ip6_prot = {
 715         .name              = "L2TP/IPv6",
 716         .owner             = THIS_MODULE,
 717         .init              = l2tp_ip6_open,
 718         .close             = l2tp_ip6_close,
 719         .bind              = l2tp_ip6_bind,
 720         .connect           = l2tp_ip6_connect,
 721         .disconnect        = l2tp_ip6_disconnect,
 722         .ioctl             = l2tp_ioctl,
 723         .destroy           = l2tp_ip6_destroy_sock,
 724         .setsockopt        = ipv6_setsockopt,
 725         .getsockopt        = ipv6_getsockopt,
 726         .sendmsg           = l2tp_ip6_sendmsg,
 727         .recvmsg           = l2tp_ip6_recvmsg,
 728         .backlog_rcv       = l2tp_ip6_backlog_recv,
 729         .hash              = l2tp_ip6_hash,
 730         .unhash            = l2tp_ip6_unhash,
 731         .obj_size          = sizeof(struct l2tp_ip6_sock),
 732 };
 733
 734 static const struct proto_ops l2tp_ip6_ops = {
 735         .family            = PF_INET6,
 736         .owner             = THIS_MODULE,
 737         .release           = inet6_release,
 738         .bind              = inet6_bind,
 739         .connect           = inet_dgram_connect,
 740         .socketpair        = sock_no_socketpair,
 741         .accept            = sock_no_accept,
 742         .getname           = l2tp_ip6_getname,
 743         .poll              = datagram_poll,
 744         .ioctl             = inet6_ioctl,
 745         .gettstamp         = sock_gettstamp,
 746         .listen            = sock_no_listen,
 747         .shutdown          = inet_shutdown,
 748         .setsockopt        = sock_common_setsockopt,
 749         .getsockopt        = sock_common_getsockopt,
 750         .sendmsg           = inet_sendmsg,
 751         .recvmsg           = sock_common_recvmsg,
 752         .mmap              = sock_no_mmap,
 753         .sendpage          = sock_no_sendpage,
 754 #ifdef CONFIG_COMPAT
 755         .compat_ioctl      = inet6_compat_ioctl,
 756 #endif
 757 };
 758
 759 static struct inet_protosw l2tp_ip6_protosw = {
 760         .type           = SOCK_DGRAM,
 761         .protocol       = IPPROTO_L2TP,
 762         .prot           = &l2tp_ip6_prot,
 763         .ops            = &l2tp_ip6_ops,
 764 };
 765
 766 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 767         .handler        = l2tp_ip6_recv,
 768 };
 769
 770 static int __init l2tp_ip6_init(void)
 771 {
 772         int err;
 773
 774         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 775
 776         err = proto_register(&l2tp_ip6_prot, 1);
 777         if (err != 0)
 778                 goto out;
 779
 780         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 781         if (err)
 782                 goto out1;
 783
 784         inet6_register_protosw(&l2tp_ip6_protosw);
 785         return 0;
 786
 787 out1:
 788         proto_unregister(&l2tp_ip6_prot);
 789 out:
 790         return err;
 791 }
 792
 793 static void __exit l2tp_ip6_exit(void)
 794 {
 795         inet6_unregister_protosw(&l2tp_ip6_protosw);
 796         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 797         proto_unregister(&l2tp_ip6_prot);
 798 }
 799
 800 module_init(l2tp_ip6_init);
 801 module_exit(l2tp_ip6_exit);
 802
 803 MODULE_LICENSE("GPL");
 804 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 805 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 806 MODULE_VERSION("1.0");
 807
 808 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 809  * enums
 810  */
 811 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 812 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);