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TOMOYO Linux Cross Reference
Linux/net/l2tp/l2tp_ip6.c

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  1 /*
  2  * L2TPv3 IP encapsulation support for IPv6
  3  *
  4  * Copyright (c) 2012 Katalix Systems Ltd
  5  *
  6  *      This program is free software; you can redistribute it and/or
  7  *      modify it under the terms of the GNU General Public License
  8  *      as published by the Free Software Foundation; either version
  9  *      2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 13 
 14 #include <linux/icmp.h>
 15 #include <linux/module.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/random.h>
 18 #include <linux/socket.h>
 19 #include <linux/l2tp.h>
 20 #include <linux/in.h>
 21 #include <linux/in6.h>
 22 #include <net/sock.h>
 23 #include <net/ip.h>
 24 #include <net/icmp.h>
 25 #include <net/udp.h>
 26 #include <net/inet_common.h>
 27 #include <net/inet_hashtables.h>
 28 #include <net/inet6_hashtables.h>
 29 #include <net/tcp_states.h>
 30 #include <net/protocol.h>
 31 #include <net/xfrm.h>
 32 
 33 #include <net/transp_v6.h>
 34 #include <net/addrconf.h>
 35 #include <net/ip6_route.h>
 36 
 37 #include "l2tp_core.h"
 38 
 39 struct l2tp_ip6_sock {
 40         /* inet_sock has to be the first member of l2tp_ip6_sock */
 41         struct inet_sock        inet;
 42 
 43         u32                     conn_id;
 44         u32                     peer_conn_id;
 45 
 46         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
 47            inet6_sk_generic */
 48         struct ipv6_pinfo       inet6;
 49 };
 50 
 51 static DEFINE_RWLOCK(l2tp_ip6_lock);
 52 static struct hlist_head l2tp_ip6_table;
 53 static struct hlist_head l2tp_ip6_bind_table;
 54 
 55 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
 56 {
 57         return (struct l2tp_ip6_sock *)sk;
 58 }
 59 
 60 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
 61                                            const struct in6_addr *laddr,
 62                                            const struct in6_addr *raddr,
 63                                            int dif, u32 tunnel_id)
 64 {
 65         struct sock *sk;
 66 
 67         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
 68                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
 69                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
 70                 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
 71 
 72                 if (!net_eq(sock_net(sk), net))
 73                         continue;
 74 
 75                 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
 76                         continue;
 77 
 78                 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
 79                     !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
 80                         continue;
 81 
 82                 if (!ipv6_addr_any(sk_raddr) && raddr &&
 83                     !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
 84                         continue;
 85 
 86                 if (l2tp->conn_id != tunnel_id)
 87                         continue;
 88 
 89                 goto found;
 90         }
 91 
 92         sk = NULL;
 93 found:
 94         return sk;
 95 }
 96 
 97 /* When processing receive frames, there are two cases to
 98  * consider. Data frames consist of a non-zero session-id and an
 99  * optional cookie. Control frames consist of a regular L2TP header
100  * preceded by 32-bits of zeros.
101  *
102  * L2TPv3 Session Header Over IP
103  *
104  *  0                   1                   2                   3
105  *  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
106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107  * |                           Session ID                          |
108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109  * |               Cookie (optional, maximum 64 bits)...
110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
111  *                                                                 |
112  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113  *
114  * L2TPv3 Control Message Header Over IP
115  *
116  *  0                   1                   2                   3
117  *  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
118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119  * |                      (32 bits of zeros)                       |
120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
123  * |                     Control Connection ID                     |
124  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
125  * |               Ns              |               Nr              |
126  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
127  *
128  * All control frames are passed to userspace.
129  */
130 static int l2tp_ip6_recv(struct sk_buff *skb)
131 {
132         struct net *net = dev_net(skb->dev);
133         struct sock *sk;
134         u32 session_id;
135         u32 tunnel_id;
136         unsigned char *ptr, *optr;
137         struct l2tp_session *session;
138         struct l2tp_tunnel *tunnel = NULL;
139         struct ipv6hdr *iph;
140         int length;
141 
142         if (!pskb_may_pull(skb, 4))
143                 goto discard;
144 
145         /* Point to L2TP header */
146         optr = ptr = skb->data;
147         session_id = ntohl(*((__be32 *) ptr));
148         ptr += 4;
149 
150         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
151          * the session_id. If it is 0, the packet is a L2TP control
152          * frame and the session_id value can be discarded.
153          */
154         if (session_id == 0) {
155                 __skb_pull(skb, 4);
156                 goto pass_up;
157         }
158 
159         /* Ok, this is a data packet. Lookup the session. */
160         session = l2tp_session_get(net, NULL, session_id);
161         if (!session)
162                 goto discard;
163 
164         tunnel = session->tunnel;
165         if (!tunnel)
166                 goto discard_sess;
167 
168         /* Trace packet contents, if enabled */
169         if (tunnel->debug & L2TP_MSG_DATA) {
170                 length = min(32u, skb->len);
171                 if (!pskb_may_pull(skb, length))
172                         goto discard_sess;
173 
174                 /* Point to L2TP header */
175                 optr = ptr = skb->data;
176                 ptr += 4;
177                 pr_debug("%s: ip recv\n", tunnel->name);
178                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
179         }
180 
181         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
182                          tunnel->recv_payload_hook);
183         l2tp_session_dec_refcount(session);
184 
185         return 0;
186 
187 pass_up:
188         /* Get the tunnel_id from the L2TP header */
189         if (!pskb_may_pull(skb, 12))
190                 goto discard;
191 
192         if ((skb->data[0] & 0xc0) != 0xc0)
193                 goto discard;
194 
195         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
196         iph = ipv6_hdr(skb);
197 
198         read_lock_bh(&l2tp_ip6_lock);
199         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
200                                     inet6_iif(skb), tunnel_id);
201         if (!sk) {
202                 read_unlock_bh(&l2tp_ip6_lock);
203                 goto discard;
204         }
205         sock_hold(sk);
206         read_unlock_bh(&l2tp_ip6_lock);
207 
208         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
209                 goto discard_put;
210 
211         nf_reset(skb);
212 
213         return sk_receive_skb(sk, skb, 1);
214 
215 discard_sess:
216         l2tp_session_dec_refcount(session);
217         goto discard;
218 
219 discard_put:
220         sock_put(sk);
221 
222 discard:
223         kfree_skb(skb);
224         return 0;
225 }
226 
227 static int l2tp_ip6_open(struct sock *sk)
228 {
229         /* Prevent autobind. We don't have ports. */
230         inet_sk(sk)->inet_num = IPPROTO_L2TP;
231 
232         write_lock_bh(&l2tp_ip6_lock);
233         sk_add_node(sk, &l2tp_ip6_table);
234         write_unlock_bh(&l2tp_ip6_lock);
235 
236         return 0;
237 }
238 
239 static void l2tp_ip6_close(struct sock *sk, long timeout)
240 {
241         write_lock_bh(&l2tp_ip6_lock);
242         hlist_del_init(&sk->sk_bind_node);
243         sk_del_node_init(sk);
244         write_unlock_bh(&l2tp_ip6_lock);
245 
246         sk_common_release(sk);
247 }
248 
249 static void l2tp_ip6_destroy_sock(struct sock *sk)
250 {
251         struct l2tp_tunnel *tunnel = sk->sk_user_data;
252 
253         lock_sock(sk);
254         ip6_flush_pending_frames(sk);
255         release_sock(sk);
256 
257         if (tunnel)
258                 l2tp_tunnel_delete(tunnel);
259 
260         inet6_destroy_sock(sk);
261 }
262 
263 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
264 {
265         struct inet_sock *inet = inet_sk(sk);
266         struct ipv6_pinfo *np = inet6_sk(sk);
267         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
268         struct net *net = sock_net(sk);
269         __be32 v4addr = 0;
270         int bound_dev_if;
271         int addr_type;
272         int err;
273 
274         if (addr->l2tp_family != AF_INET6)
275                 return -EINVAL;
276         if (addr_len < sizeof(*addr))
277                 return -EINVAL;
278 
279         addr_type = ipv6_addr_type(&addr->l2tp_addr);
280 
281         /* l2tp_ip6 sockets are IPv6 only */
282         if (addr_type == IPV6_ADDR_MAPPED)
283                 return -EADDRNOTAVAIL;
284 
285         /* L2TP is point-point, not multicast */
286         if (addr_type & IPV6_ADDR_MULTICAST)
287                 return -EADDRNOTAVAIL;
288 
289         lock_sock(sk);
290 
291         err = -EINVAL;
292         if (!sock_flag(sk, SOCK_ZAPPED))
293                 goto out_unlock;
294 
295         if (sk->sk_state != TCP_CLOSE)
296                 goto out_unlock;
297 
298         bound_dev_if = sk->sk_bound_dev_if;
299 
300         /* Check if the address belongs to the host. */
301         rcu_read_lock();
302         if (addr_type != IPV6_ADDR_ANY) {
303                 struct net_device *dev = NULL;
304 
305                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
306                         if (addr->l2tp_scope_id)
307                                 bound_dev_if = addr->l2tp_scope_id;
308 
309                         /* Binding to link-local address requires an
310                          * interface.
311                          */
312                         if (!bound_dev_if)
313                                 goto out_unlock_rcu;
314 
315                         err = -ENODEV;
316                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
317                         if (!dev)
318                                 goto out_unlock_rcu;
319                 }
320 
321                 /* ipv4 addr of the socket is invalid.  Only the
322                  * unspecified and mapped address have a v4 equivalent.
323                  */
324                 v4addr = LOOPBACK4_IPV6;
325                 err = -EADDRNOTAVAIL;
326                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
327                         goto out_unlock_rcu;
328         }
329         rcu_read_unlock();
330 
331         write_lock_bh(&l2tp_ip6_lock);
332         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
333                                    addr->l2tp_conn_id)) {
334                 write_unlock_bh(&l2tp_ip6_lock);
335                 err = -EADDRINUSE;
336                 goto out_unlock;
337         }
338 
339         inet->inet_saddr = v4addr;
340         inet->inet_rcv_saddr = v4addr;
341         sk->sk_bound_dev_if = bound_dev_if;
342         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
343         np->saddr = addr->l2tp_addr;
344 
345         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
346 
347         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
348         sk_del_node_init(sk);
349         write_unlock_bh(&l2tp_ip6_lock);
350 
351         sock_reset_flag(sk, SOCK_ZAPPED);
352         release_sock(sk);
353         return 0;
354 
355 out_unlock_rcu:
356         rcu_read_unlock();
357 out_unlock:
358         release_sock(sk);
359 
360         return err;
361 }
362 
363 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
364                             int addr_len)
365 {
366         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
367         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
368         struct in6_addr *daddr;
369         int     addr_type;
370         int rc;
371 
372         if (addr_len < sizeof(*lsa))
373                 return -EINVAL;
374 
375         if (usin->sin6_family != AF_INET6)
376                 return -EINVAL;
377 
378         addr_type = ipv6_addr_type(&usin->sin6_addr);
379         if (addr_type & IPV6_ADDR_MULTICAST)
380                 return -EINVAL;
381 
382         if (addr_type & IPV6_ADDR_MAPPED) {
383                 daddr = &usin->sin6_addr;
384                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
385                         return -EINVAL;
386         }
387 
388         lock_sock(sk);
389 
390          /* Must bind first - autobinding does not work */
391         if (sock_flag(sk, SOCK_ZAPPED)) {
392                 rc = -EINVAL;
393                 goto out_sk;
394         }
395 
396         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
397         if (rc < 0)
398                 goto out_sk;
399 
400         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
401 
402         write_lock_bh(&l2tp_ip6_lock);
403         hlist_del_init(&sk->sk_bind_node);
404         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
405         write_unlock_bh(&l2tp_ip6_lock);
406 
407 out_sk:
408         release_sock(sk);
409 
410         return rc;
411 }
412 
413 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
414 {
415         if (sock_flag(sk, SOCK_ZAPPED))
416                 return 0;
417 
418         return __udp_disconnect(sk, flags);
419 }
420 
421 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
422                             int *uaddr_len, int peer)
423 {
424         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
425         struct sock *sk = sock->sk;
426         struct ipv6_pinfo *np = inet6_sk(sk);
427         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
428 
429         lsa->l2tp_family = AF_INET6;
430         lsa->l2tp_flowinfo = 0;
431         lsa->l2tp_scope_id = 0;
432         lsa->l2tp_unused = 0;
433         if (peer) {
434                 if (!lsk->peer_conn_id)
435                         return -ENOTCONN;
436                 lsa->l2tp_conn_id = lsk->peer_conn_id;
437                 lsa->l2tp_addr = sk->sk_v6_daddr;
438                 if (np->sndflow)
439                         lsa->l2tp_flowinfo = np->flow_label;
440         } else {
441                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
442                         lsa->l2tp_addr = np->saddr;
443                 else
444                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
445 
446                 lsa->l2tp_conn_id = lsk->conn_id;
447         }
448         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
449                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
450         *uaddr_len = sizeof(*lsa);
451         return 0;
452 }
453 
454 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
455 {
456         int rc;
457 
458         /* Charge it to the socket, dropping if the queue is full. */
459         rc = sock_queue_rcv_skb(sk, skb);
460         if (rc < 0)
461                 goto drop;
462 
463         return 0;
464 
465 drop:
466         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
467         kfree_skb(skb);
468         return -1;
469 }
470 
471 static int l2tp_ip6_push_pending_frames(struct sock *sk)
472 {
473         struct sk_buff *skb;
474         __be32 *transhdr = NULL;
475         int err = 0;
476 
477         skb = skb_peek(&sk->sk_write_queue);
478         if (skb == NULL)
479                 goto out;
480 
481         transhdr = (__be32 *)skb_transport_header(skb);
482         *transhdr = 0;
483 
484         err = ip6_push_pending_frames(sk);
485 
486 out:
487         return err;
488 }
489 
490 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
491  * control frames.
492  */
493 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
494 {
495         struct ipv6_txoptions opt_space;
496         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
497         struct in6_addr *daddr, *final_p, final;
498         struct ipv6_pinfo *np = inet6_sk(sk);
499         struct ipv6_txoptions *opt_to_free = NULL;
500         struct ipv6_txoptions *opt = NULL;
501         struct ip6_flowlabel *flowlabel = NULL;
502         struct dst_entry *dst = NULL;
503         struct flowi6 fl6;
504         struct sockcm_cookie sockc_unused = {0};
505         struct ipcm6_cookie ipc6;
506         int addr_len = msg->msg_namelen;
507         int transhdrlen = 4; /* zero session-id */
508         int ulen = len + transhdrlen;
509         int err;
510 
511         /* Rough check on arithmetic overflow,
512            better check is made in ip6_append_data().
513          */
514         if (len > INT_MAX)
515                 return -EMSGSIZE;
516 
517         /* Mirror BSD error message compatibility */
518         if (msg->msg_flags & MSG_OOB)
519                 return -EOPNOTSUPP;
520 
521         /*
522          *      Get and verify the address.
523          */
524         memset(&fl6, 0, sizeof(fl6));
525 
526         fl6.flowi6_mark = sk->sk_mark;
527         fl6.flowi6_uid = sk->sk_uid;
528 
529         ipc6.hlimit = -1;
530         ipc6.tclass = -1;
531         ipc6.dontfrag = -1;
532 
533         if (lsa) {
534                 if (addr_len < SIN6_LEN_RFC2133)
535                         return -EINVAL;
536 
537                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
538                         return -EAFNOSUPPORT;
539 
540                 daddr = &lsa->l2tp_addr;
541                 if (np->sndflow) {
542                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
543                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
544                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
545                                 if (flowlabel == NULL)
546                                         return -EINVAL;
547                         }
548                 }
549 
550                 /*
551                  * Otherwise it will be difficult to maintain
552                  * sk->sk_dst_cache.
553                  */
554                 if (sk->sk_state == TCP_ESTABLISHED &&
555                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
556                         daddr = &sk->sk_v6_daddr;
557 
558                 if (addr_len >= sizeof(struct sockaddr_in6) &&
559                     lsa->l2tp_scope_id &&
560                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
561                         fl6.flowi6_oif = lsa->l2tp_scope_id;
562         } else {
563                 if (sk->sk_state != TCP_ESTABLISHED)
564                         return -EDESTADDRREQ;
565 
566                 daddr = &sk->sk_v6_daddr;
567                 fl6.flowlabel = np->flow_label;
568         }
569 
570         if (fl6.flowi6_oif == 0)
571                 fl6.flowi6_oif = sk->sk_bound_dev_if;
572 
573         if (msg->msg_controllen) {
574                 opt = &opt_space;
575                 memset(opt, 0, sizeof(struct ipv6_txoptions));
576                 opt->tot_len = sizeof(struct ipv6_txoptions);
577                 ipc6.opt = opt;
578 
579                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
580                                             &sockc_unused);
581                 if (err < 0) {
582                         fl6_sock_release(flowlabel);
583                         return err;
584                 }
585                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
586                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
587                         if (flowlabel == NULL)
588                                 return -EINVAL;
589                 }
590                 if (!(opt->opt_nflen|opt->opt_flen))
591                         opt = NULL;
592         }
593 
594         if (!opt) {
595                 opt = txopt_get(np);
596                 opt_to_free = opt;
597         }
598         if (flowlabel)
599                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
600         opt = ipv6_fixup_options(&opt_space, opt);
601         ipc6.opt = opt;
602 
603         fl6.flowi6_proto = sk->sk_protocol;
604         if (!ipv6_addr_any(daddr))
605                 fl6.daddr = *daddr;
606         else
607                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
608         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
609                 fl6.saddr = np->saddr;
610 
611         final_p = fl6_update_dst(&fl6, opt, &final);
612 
613         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
614                 fl6.flowi6_oif = np->mcast_oif;
615         else if (!fl6.flowi6_oif)
616                 fl6.flowi6_oif = np->ucast_oif;
617 
618         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
619 
620         if (ipc6.tclass < 0)
621                 ipc6.tclass = np->tclass;
622 
623         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
624 
625         dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
626         if (IS_ERR(dst)) {
627                 err = PTR_ERR(dst);
628                 goto out;
629         }
630 
631         if (ipc6.hlimit < 0)
632                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
633 
634         if (ipc6.dontfrag < 0)
635                 ipc6.dontfrag = np->dontfrag;
636 
637         if (msg->msg_flags & MSG_CONFIRM)
638                 goto do_confirm;
639 
640 back_from_confirm:
641         lock_sock(sk);
642         err = ip6_append_data(sk, ip_generic_getfrag, msg,
643                               ulen, transhdrlen, &ipc6,
644                               &fl6, (struct rt6_info *)dst,
645                               msg->msg_flags, &sockc_unused);
646         if (err)
647                 ip6_flush_pending_frames(sk);
648         else if (!(msg->msg_flags & MSG_MORE))
649                 err = l2tp_ip6_push_pending_frames(sk);
650         release_sock(sk);
651 done:
652         dst_release(dst);
653 out:
654         fl6_sock_release(flowlabel);
655         txopt_put(opt_to_free);
656 
657         return err < 0 ? err : len;
658 
659 do_confirm:
660         if (msg->msg_flags & MSG_PROBE)
661                 dst_confirm_neigh(dst, &fl6.daddr);
662         if (!(msg->msg_flags & MSG_PROBE) || len)
663                 goto back_from_confirm;
664         err = 0;
665         goto done;
666 }
667 
668 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
669                             int noblock, int flags, int *addr_len)
670 {
671         struct ipv6_pinfo *np = inet6_sk(sk);
672         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
673         size_t copied = 0;
674         int err = -EOPNOTSUPP;
675         struct sk_buff *skb;
676 
677         if (flags & MSG_OOB)
678                 goto out;
679 
680         if (addr_len)
681                 *addr_len = sizeof(*lsa);
682 
683         if (flags & MSG_ERRQUEUE)
684                 return ipv6_recv_error(sk, msg, len, addr_len);
685 
686         skb = skb_recv_datagram(sk, flags, noblock, &err);
687         if (!skb)
688                 goto out;
689 
690         copied = skb->len;
691         if (len < copied) {
692                 msg->msg_flags |= MSG_TRUNC;
693                 copied = len;
694         }
695 
696         err = skb_copy_datagram_msg(skb, 0, msg, copied);
697         if (err)
698                 goto done;
699 
700         sock_recv_timestamp(msg, sk, skb);
701 
702         /* Copy the address. */
703         if (lsa) {
704                 lsa->l2tp_family = AF_INET6;
705                 lsa->l2tp_unused = 0;
706                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
707                 lsa->l2tp_flowinfo = 0;
708                 lsa->l2tp_scope_id = 0;
709                 lsa->l2tp_conn_id = 0;
710                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
711                         lsa->l2tp_scope_id = inet6_iif(skb);
712         }
713 
714         if (np->rxopt.all)
715                 ip6_datagram_recv_ctl(sk, msg, skb);
716 
717         if (flags & MSG_TRUNC)
718                 copied = skb->len;
719 done:
720         skb_free_datagram(sk, skb);
721 out:
722         return err ? err : copied;
723 }
724 
725 static struct proto l2tp_ip6_prot = {
726         .name              = "L2TP/IPv6",
727         .owner             = THIS_MODULE,
728         .init              = l2tp_ip6_open,
729         .close             = l2tp_ip6_close,
730         .bind              = l2tp_ip6_bind,
731         .connect           = l2tp_ip6_connect,
732         .disconnect        = l2tp_ip6_disconnect,
733         .ioctl             = l2tp_ioctl,
734         .destroy           = l2tp_ip6_destroy_sock,
735         .setsockopt        = ipv6_setsockopt,
736         .getsockopt        = ipv6_getsockopt,
737         .sendmsg           = l2tp_ip6_sendmsg,
738         .recvmsg           = l2tp_ip6_recvmsg,
739         .backlog_rcv       = l2tp_ip6_backlog_recv,
740         .hash              = inet6_hash,
741         .unhash            = inet_unhash,
742         .obj_size          = sizeof(struct l2tp_ip6_sock),
743 #ifdef CONFIG_COMPAT
744         .compat_setsockopt = compat_ipv6_setsockopt,
745         .compat_getsockopt = compat_ipv6_getsockopt,
746 #endif
747 };
748 
749 static const struct proto_ops l2tp_ip6_ops = {
750         .family            = PF_INET6,
751         .owner             = THIS_MODULE,
752         .release           = inet6_release,
753         .bind              = inet6_bind,
754         .connect           = inet_dgram_connect,
755         .socketpair        = sock_no_socketpair,
756         .accept            = sock_no_accept,
757         .getname           = l2tp_ip6_getname,
758         .poll              = datagram_poll,
759         .ioctl             = inet6_ioctl,
760         .listen            = sock_no_listen,
761         .shutdown          = inet_shutdown,
762         .setsockopt        = sock_common_setsockopt,
763         .getsockopt        = sock_common_getsockopt,
764         .sendmsg           = inet_sendmsg,
765         .recvmsg           = sock_common_recvmsg,
766         .mmap              = sock_no_mmap,
767         .sendpage          = sock_no_sendpage,
768 #ifdef CONFIG_COMPAT
769         .compat_setsockopt = compat_sock_common_setsockopt,
770         .compat_getsockopt = compat_sock_common_getsockopt,
771 #endif
772 };
773 
774 static struct inet_protosw l2tp_ip6_protosw = {
775         .type           = SOCK_DGRAM,
776         .protocol       = IPPROTO_L2TP,
777         .prot           = &l2tp_ip6_prot,
778         .ops            = &l2tp_ip6_ops,
779 };
780 
781 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
782         .handler        = l2tp_ip6_recv,
783 };
784 
785 static int __init l2tp_ip6_init(void)
786 {
787         int err;
788 
789         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
790 
791         err = proto_register(&l2tp_ip6_prot, 1);
792         if (err != 0)
793                 goto out;
794 
795         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
796         if (err)
797                 goto out1;
798 
799         inet6_register_protosw(&l2tp_ip6_protosw);
800         return 0;
801 
802 out1:
803         proto_unregister(&l2tp_ip6_prot);
804 out:
805         return err;
806 }
807 
808 static void __exit l2tp_ip6_exit(void)
809 {
810         inet6_unregister_protosw(&l2tp_ip6_protosw);
811         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
812         proto_unregister(&l2tp_ip6_prot);
813 }
814 
815 module_init(l2tp_ip6_init);
816 module_exit(l2tp_ip6_exit);
817 
818 MODULE_LICENSE("GPL");
819 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
820 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
821 MODULE_VERSION("1.0");
822 
823 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
824  * enums
825  */
826 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
827 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
828 

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