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Linux/net/l2tp/l2tp_ip6.c

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  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/inet_hashtables.h>
 24 #include <net/inet6_hashtables.h>
 25 #include <net/tcp_states.h>
 26 #include <net/protocol.h>
 27 #include <net/xfrm.h>
 28 
 29 #include <net/transp_v6.h>
 30 #include <net/addrconf.h>
 31 #include <net/ip6_route.h>
 32 
 33 #include "l2tp_core.h"
 34 
 35 struct l2tp_ip6_sock {
 36         /* inet_sock has to be the first member of l2tp_ip6_sock */
 37         struct inet_sock        inet;
 38 
 39         u32                     conn_id;
 40         u32                     peer_conn_id;
 41 
 42         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
 43            inet6_sk_generic */
 44         struct ipv6_pinfo       inet6;
 45 };
 46 
 47 static DEFINE_RWLOCK(l2tp_ip6_lock);
 48 static struct hlist_head l2tp_ip6_table;
 49 static struct hlist_head l2tp_ip6_bind_table;
 50 
 51 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
 52 {
 53         return (struct l2tp_ip6_sock *)sk;
 54 }
 55 
 56 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
 57                                            const struct in6_addr *laddr,
 58                                            const struct in6_addr *raddr,
 59                                            int dif, u32 tunnel_id)
 60 {
 61         struct sock *sk;
 62 
 63         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
 64                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
 65                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
 66                 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
 67 
 68                 if (!net_eq(sock_net(sk), net))
 69                         continue;
 70 
 71                 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
 72                         continue;
 73 
 74                 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
 75                     !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
 76                         continue;
 77 
 78                 if (!ipv6_addr_any(sk_raddr) && raddr &&
 79                     !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
 80                         continue;
 81 
 82                 if (l2tp->conn_id != tunnel_id)
 83                         continue;
 84 
 85                 goto found;
 86         }
 87 
 88         sk = NULL;
 89 found:
 90         return sk;
 91 }
 92 
 93 /* When processing receive frames, there are two cases to
 94  * consider. Data frames consist of a non-zero session-id and an
 95  * optional cookie. Control frames consist of a regular L2TP header
 96  * preceded by 32-bits of zeros.
 97  *
 98  * L2TPv3 Session Header Over IP
 99  *
100  *  0                   1                   2                   3
101  *  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
102  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103  * |                           Session ID                          |
104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105  * |               Cookie (optional, maximum 64 bits)...
106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107  *                                                                 |
108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109  *
110  * L2TPv3 Control Message Header Over IP
111  *
112  *  0                   1                   2                   3
113  *  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
114  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
115  * |                      (32 bits of zeros)                       |
116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119  * |                     Control Connection ID                     |
120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121  * |               Ns              |               Nr              |
122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
123  *
124  * All control frames are passed to userspace.
125  */
126 static int l2tp_ip6_recv(struct sk_buff *skb)
127 {
128         struct net *net = dev_net(skb->dev);
129         struct sock *sk;
130         u32 session_id;
131         u32 tunnel_id;
132         unsigned char *ptr, *optr;
133         struct l2tp_session *session;
134         struct l2tp_tunnel *tunnel = NULL;
135         struct ipv6hdr *iph;
136         int length;
137 
138         if (!pskb_may_pull(skb, 4))
139                 goto discard;
140 
141         /* Point to L2TP header */
142         optr = ptr = skb->data;
143         session_id = ntohl(*((__be32 *) ptr));
144         ptr += 4;
145 
146         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
147          * the session_id. If it is 0, the packet is a L2TP control
148          * frame and the session_id value can be discarded.
149          */
150         if (session_id == 0) {
151                 __skb_pull(skb, 4);
152                 goto pass_up;
153         }
154 
155         /* Ok, this is a data packet. Lookup the session. */
156         session = l2tp_session_get(net, session_id);
157         if (!session)
158                 goto discard;
159 
160         tunnel = session->tunnel;
161         if (!tunnel)
162                 goto discard_sess;
163 
164         /* Trace packet contents, if enabled */
165         if (tunnel->debug & L2TP_MSG_DATA) {
166                 length = min(32u, skb->len);
167                 if (!pskb_may_pull(skb, length))
168                         goto discard_sess;
169 
170                 /* Point to L2TP header */
171                 optr = ptr = skb->data;
172                 ptr += 4;
173                 pr_debug("%s: ip recv\n", tunnel->name);
174                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
175         }
176 
177         if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
178                 goto discard_sess;
179 
180         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
181         l2tp_session_dec_refcount(session);
182 
183         return 0;
184 
185 pass_up:
186         /* Get the tunnel_id from the L2TP header */
187         if (!pskb_may_pull(skb, 12))
188                 goto discard;
189 
190         if ((skb->data[0] & 0xc0) != 0xc0)
191                 goto discard;
192 
193         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
194         iph = ipv6_hdr(skb);
195 
196         read_lock_bh(&l2tp_ip6_lock);
197         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
198                                     inet6_iif(skb), tunnel_id);
199         if (!sk) {
200                 read_unlock_bh(&l2tp_ip6_lock);
201                 goto discard;
202         }
203         sock_hold(sk);
204         read_unlock_bh(&l2tp_ip6_lock);
205 
206         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
207                 goto discard_put;
208 
209         nf_reset(skb);
210 
211         return sk_receive_skb(sk, skb, 1);
212 
213 discard_sess:
214         l2tp_session_dec_refcount(session);
215         goto discard;
216 
217 discard_put:
218         sock_put(sk);
219 
220 discard:
221         kfree_skb(skb);
222         return 0;
223 }
224 
225 static int l2tp_ip6_open(struct sock *sk)
226 {
227         /* Prevent autobind. We don't have ports. */
228         inet_sk(sk)->inet_num = IPPROTO_L2TP;
229 
230         write_lock_bh(&l2tp_ip6_lock);
231         sk_add_node(sk, &l2tp_ip6_table);
232         write_unlock_bh(&l2tp_ip6_lock);
233 
234         return 0;
235 }
236 
237 static void l2tp_ip6_close(struct sock *sk, long timeout)
238 {
239         write_lock_bh(&l2tp_ip6_lock);
240         hlist_del_init(&sk->sk_bind_node);
241         sk_del_node_init(sk);
242         write_unlock_bh(&l2tp_ip6_lock);
243 
244         sk_common_release(sk);
245 }
246 
247 static void l2tp_ip6_destroy_sock(struct sock *sk)
248 {
249         struct l2tp_tunnel *tunnel = sk->sk_user_data;
250 
251         lock_sock(sk);
252         ip6_flush_pending_frames(sk);
253         release_sock(sk);
254 
255         if (tunnel)
256                 l2tp_tunnel_delete(tunnel);
257 
258         inet6_destroy_sock(sk);
259 }
260 
261 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
262 {
263         struct inet_sock *inet = inet_sk(sk);
264         struct ipv6_pinfo *np = inet6_sk(sk);
265         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
266         struct net *net = sock_net(sk);
267         __be32 v4addr = 0;
268         int bound_dev_if;
269         int addr_type;
270         int err;
271 
272         if (addr->l2tp_family != AF_INET6)
273                 return -EINVAL;
274         if (addr_len < sizeof(*addr))
275                 return -EINVAL;
276 
277         addr_type = ipv6_addr_type(&addr->l2tp_addr);
278 
279         /* l2tp_ip6 sockets are IPv6 only */
280         if (addr_type == IPV6_ADDR_MAPPED)
281                 return -EADDRNOTAVAIL;
282 
283         /* L2TP is point-point, not multicast */
284         if (addr_type & IPV6_ADDR_MULTICAST)
285                 return -EADDRNOTAVAIL;
286 
287         lock_sock(sk);
288 
289         err = -EINVAL;
290         if (!sock_flag(sk, SOCK_ZAPPED))
291                 goto out_unlock;
292 
293         if (sk->sk_state != TCP_CLOSE)
294                 goto out_unlock;
295 
296         bound_dev_if = sk->sk_bound_dev_if;
297 
298         /* Check if the address belongs to the host. */
299         rcu_read_lock();
300         if (addr_type != IPV6_ADDR_ANY) {
301                 struct net_device *dev = NULL;
302 
303                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
304                         if (addr->l2tp_scope_id)
305                                 bound_dev_if = addr->l2tp_scope_id;
306 
307                         /* Binding to link-local address requires an
308                          * interface.
309                          */
310                         if (!bound_dev_if)
311                                 goto out_unlock_rcu;
312 
313                         err = -ENODEV;
314                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
315                         if (!dev)
316                                 goto out_unlock_rcu;
317                 }
318 
319                 /* ipv4 addr of the socket is invalid.  Only the
320                  * unspecified and mapped address have a v4 equivalent.
321                  */
322                 v4addr = LOOPBACK4_IPV6;
323                 err = -EADDRNOTAVAIL;
324                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
325                         goto out_unlock_rcu;
326         }
327         rcu_read_unlock();
328 
329         write_lock_bh(&l2tp_ip6_lock);
330         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
331                                    addr->l2tp_conn_id)) {
332                 write_unlock_bh(&l2tp_ip6_lock);
333                 err = -EADDRINUSE;
334                 goto out_unlock;
335         }
336 
337         inet->inet_saddr = v4addr;
338         inet->inet_rcv_saddr = v4addr;
339         sk->sk_bound_dev_if = bound_dev_if;
340         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
341         np->saddr = addr->l2tp_addr;
342 
343         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
344 
345         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
346         sk_del_node_init(sk);
347         write_unlock_bh(&l2tp_ip6_lock);
348 
349         sock_reset_flag(sk, SOCK_ZAPPED);
350         release_sock(sk);
351         return 0;
352 
353 out_unlock_rcu:
354         rcu_read_unlock();
355 out_unlock:
356         release_sock(sk);
357 
358         return err;
359 }
360 
361 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
362                             int addr_len)
363 {
364         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
365         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
366         struct in6_addr *daddr;
367         int     addr_type;
368         int rc;
369 
370         if (addr_len < sizeof(*lsa))
371                 return -EINVAL;
372 
373         if (usin->sin6_family != AF_INET6)
374                 return -EINVAL;
375 
376         addr_type = ipv6_addr_type(&usin->sin6_addr);
377         if (addr_type & IPV6_ADDR_MULTICAST)
378                 return -EINVAL;
379 
380         if (addr_type & IPV6_ADDR_MAPPED) {
381                 daddr = &usin->sin6_addr;
382                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
383                         return -EINVAL;
384         }
385 
386         lock_sock(sk);
387 
388          /* Must bind first - autobinding does not work */
389         if (sock_flag(sk, SOCK_ZAPPED)) {
390                 rc = -EINVAL;
391                 goto out_sk;
392         }
393 
394         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
395         if (rc < 0)
396                 goto out_sk;
397 
398         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
399 
400         write_lock_bh(&l2tp_ip6_lock);
401         hlist_del_init(&sk->sk_bind_node);
402         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
403         write_unlock_bh(&l2tp_ip6_lock);
404 
405 out_sk:
406         release_sock(sk);
407 
408         return rc;
409 }
410 
411 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
412 {
413         if (sock_flag(sk, SOCK_ZAPPED))
414                 return 0;
415 
416         return __udp_disconnect(sk, flags);
417 }
418 
419 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
420                             int peer)
421 {
422         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
423         struct sock *sk = sock->sk;
424         struct ipv6_pinfo *np = inet6_sk(sk);
425         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
426 
427         lsa->l2tp_family = AF_INET6;
428         lsa->l2tp_flowinfo = 0;
429         lsa->l2tp_scope_id = 0;
430         lsa->l2tp_unused = 0;
431         if (peer) {
432                 if (!lsk->peer_conn_id)
433                         return -ENOTCONN;
434                 lsa->l2tp_conn_id = lsk->peer_conn_id;
435                 lsa->l2tp_addr = sk->sk_v6_daddr;
436                 if (np->sndflow)
437                         lsa->l2tp_flowinfo = np->flow_label;
438         } else {
439                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
440                         lsa->l2tp_addr = np->saddr;
441                 else
442                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
443 
444                 lsa->l2tp_conn_id = lsk->conn_id;
445         }
446         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
447                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
448         return sizeof(*lsa);
449 }
450 
451 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
452 {
453         int rc;
454 
455         /* Charge it to the socket, dropping if the queue is full. */
456         rc = sock_queue_rcv_skb(sk, skb);
457         if (rc < 0)
458                 goto drop;
459 
460         return 0;
461 
462 drop:
463         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
464         kfree_skb(skb);
465         return -1;
466 }
467 
468 static int l2tp_ip6_push_pending_frames(struct sock *sk)
469 {
470         struct sk_buff *skb;
471         __be32 *transhdr = NULL;
472         int err = 0;
473 
474         skb = skb_peek(&sk->sk_write_queue);
475         if (skb == NULL)
476                 goto out;
477 
478         transhdr = (__be32 *)skb_transport_header(skb);
479         *transhdr = 0;
480 
481         err = ip6_push_pending_frames(sk);
482 
483 out:
484         return err;
485 }
486 
487 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
488  * control frames.
489  */
490 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
491 {
492         struct ipv6_txoptions opt_space;
493         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
494         struct in6_addr *daddr, *final_p, final;
495         struct ipv6_pinfo *np = inet6_sk(sk);
496         struct ipv6_txoptions *opt_to_free = NULL;
497         struct ipv6_txoptions *opt = NULL;
498         struct ip6_flowlabel *flowlabel = NULL;
499         struct dst_entry *dst = NULL;
500         struct flowi6 fl6;
501         struct ipcm6_cookie ipc6;
502         int addr_len = msg->msg_namelen;
503         int transhdrlen = 4; /* zero session-id */
504         int ulen = len + transhdrlen;
505         int err;
506 
507         /* Rough check on arithmetic overflow,
508            better check is made in ip6_append_data().
509          */
510         if (len > INT_MAX)
511                 return -EMSGSIZE;
512 
513         /* Mirror BSD error message compatibility */
514         if (msg->msg_flags & MSG_OOB)
515                 return -EOPNOTSUPP;
516 
517         /*
518          *      Get and verify the address.
519          */
520         memset(&fl6, 0, sizeof(fl6));
521 
522         fl6.flowi6_mark = sk->sk_mark;
523         fl6.flowi6_uid = sk->sk_uid;
524 
525         ipcm6_init(&ipc6);
526 
527         if (lsa) {
528                 if (addr_len < SIN6_LEN_RFC2133)
529                         return -EINVAL;
530 
531                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
532                         return -EAFNOSUPPORT;
533 
534                 daddr = &lsa->l2tp_addr;
535                 if (np->sndflow) {
536                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
537                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
538                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
539                                 if (IS_ERR(flowlabel))
540                                         return -EINVAL;
541                         }
542                 }
543 
544                 /*
545                  * Otherwise it will be difficult to maintain
546                  * sk->sk_dst_cache.
547                  */
548                 if (sk->sk_state == TCP_ESTABLISHED &&
549                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
550                         daddr = &sk->sk_v6_daddr;
551 
552                 if (addr_len >= sizeof(struct sockaddr_in6) &&
553                     lsa->l2tp_scope_id &&
554                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
555                         fl6.flowi6_oif = lsa->l2tp_scope_id;
556         } else {
557                 if (sk->sk_state != TCP_ESTABLISHED)
558                         return -EDESTADDRREQ;
559 
560                 daddr = &sk->sk_v6_daddr;
561                 fl6.flowlabel = np->flow_label;
562         }
563 
564         if (fl6.flowi6_oif == 0)
565                 fl6.flowi6_oif = sk->sk_bound_dev_if;
566 
567         if (msg->msg_controllen) {
568                 opt = &opt_space;
569                 memset(opt, 0, sizeof(struct ipv6_txoptions));
570                 opt->tot_len = sizeof(struct ipv6_txoptions);
571                 ipc6.opt = opt;
572 
573                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
574                 if (err < 0) {
575                         fl6_sock_release(flowlabel);
576                         return err;
577                 }
578                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
579                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
580                         if (IS_ERR(flowlabel))
581                                 return -EINVAL;
582                 }
583                 if (!(opt->opt_nflen|opt->opt_flen))
584                         opt = NULL;
585         }
586 
587         if (!opt) {
588                 opt = txopt_get(np);
589                 opt_to_free = opt;
590         }
591         if (flowlabel)
592                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
593         opt = ipv6_fixup_options(&opt_space, opt);
594         ipc6.opt = opt;
595 
596         fl6.flowi6_proto = sk->sk_protocol;
597         if (!ipv6_addr_any(daddr))
598                 fl6.daddr = *daddr;
599         else
600                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
601         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
602                 fl6.saddr = np->saddr;
603 
604         final_p = fl6_update_dst(&fl6, opt, &final);
605 
606         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
607                 fl6.flowi6_oif = np->mcast_oif;
608         else if (!fl6.flowi6_oif)
609                 fl6.flowi6_oif = np->ucast_oif;
610 
611         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
612 
613         if (ipc6.tclass < 0)
614                 ipc6.tclass = np->tclass;
615 
616         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
617 
618         dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
619         if (IS_ERR(dst)) {
620                 err = PTR_ERR(dst);
621                 goto out;
622         }
623 
624         if (ipc6.hlimit < 0)
625                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
626 
627         if (ipc6.dontfrag < 0)
628                 ipc6.dontfrag = np->dontfrag;
629 
630         if (msg->msg_flags & MSG_CONFIRM)
631                 goto do_confirm;
632 
633 back_from_confirm:
634         lock_sock(sk);
635         err = ip6_append_data(sk, ip_generic_getfrag, msg,
636                               ulen, transhdrlen, &ipc6,
637                               &fl6, (struct rt6_info *)dst,
638                               msg->msg_flags);
639         if (err)
640                 ip6_flush_pending_frames(sk);
641         else if (!(msg->msg_flags & MSG_MORE))
642                 err = l2tp_ip6_push_pending_frames(sk);
643         release_sock(sk);
644 done:
645         dst_release(dst);
646 out:
647         fl6_sock_release(flowlabel);
648         txopt_put(opt_to_free);
649 
650         return err < 0 ? err : len;
651 
652 do_confirm:
653         if (msg->msg_flags & MSG_PROBE)
654                 dst_confirm_neigh(dst, &fl6.daddr);
655         if (!(msg->msg_flags & MSG_PROBE) || len)
656                 goto back_from_confirm;
657         err = 0;
658         goto done;
659 }
660 
661 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
662                             int noblock, int flags, int *addr_len)
663 {
664         struct ipv6_pinfo *np = inet6_sk(sk);
665         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
666         size_t copied = 0;
667         int err = -EOPNOTSUPP;
668         struct sk_buff *skb;
669 
670         if (flags & MSG_OOB)
671                 goto out;
672 
673         if (flags & MSG_ERRQUEUE)
674                 return ipv6_recv_error(sk, msg, len, addr_len);
675 
676         skb = skb_recv_datagram(sk, flags, noblock, &err);
677         if (!skb)
678                 goto out;
679 
680         copied = skb->len;
681         if (len < copied) {
682                 msg->msg_flags |= MSG_TRUNC;
683                 copied = len;
684         }
685 
686         err = skb_copy_datagram_msg(skb, 0, msg, copied);
687         if (err)
688                 goto done;
689 
690         sock_recv_timestamp(msg, sk, skb);
691 
692         /* Copy the address. */
693         if (lsa) {
694                 lsa->l2tp_family = AF_INET6;
695                 lsa->l2tp_unused = 0;
696                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
697                 lsa->l2tp_flowinfo = 0;
698                 lsa->l2tp_scope_id = 0;
699                 lsa->l2tp_conn_id = 0;
700                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
701                         lsa->l2tp_scope_id = inet6_iif(skb);
702                 *addr_len = sizeof(*lsa);
703         }
704 
705         if (np->rxopt.all)
706                 ip6_datagram_recv_ctl(sk, msg, skb);
707 
708         if (flags & MSG_TRUNC)
709                 copied = skb->len;
710 done:
711         skb_free_datagram(sk, skb);
712 out:
713         return err ? err : copied;
714 }
715 
716 static struct proto l2tp_ip6_prot = {
717         .name              = "L2TP/IPv6",
718         .owner             = THIS_MODULE,
719         .init              = l2tp_ip6_open,
720         .close             = l2tp_ip6_close,
721         .bind              = l2tp_ip6_bind,
722         .connect           = l2tp_ip6_connect,
723         .disconnect        = l2tp_ip6_disconnect,
724         .ioctl             = l2tp_ioctl,
725         .destroy           = l2tp_ip6_destroy_sock,
726         .setsockopt        = ipv6_setsockopt,
727         .getsockopt        = ipv6_getsockopt,
728         .sendmsg           = l2tp_ip6_sendmsg,
729         .recvmsg           = l2tp_ip6_recvmsg,
730         .backlog_rcv       = l2tp_ip6_backlog_recv,
731         .hash              = inet6_hash,
732         .unhash            = inet_unhash,
733         .obj_size          = sizeof(struct l2tp_ip6_sock),
734 #ifdef CONFIG_COMPAT
735         .compat_setsockopt = compat_ipv6_setsockopt,
736         .compat_getsockopt = compat_ipv6_getsockopt,
737 #endif
738 };
739 
740 static const struct proto_ops l2tp_ip6_ops = {
741         .family            = PF_INET6,
742         .owner             = THIS_MODULE,
743         .release           = inet6_release,
744         .bind              = inet6_bind,
745         .connect           = inet_dgram_connect,
746         .socketpair        = sock_no_socketpair,
747         .accept            = sock_no_accept,
748         .getname           = l2tp_ip6_getname,
749         .poll              = datagram_poll,
750         .ioctl             = inet6_ioctl,
751         .gettstamp         = sock_gettstamp,
752         .listen            = sock_no_listen,
753         .shutdown          = inet_shutdown,
754         .setsockopt        = sock_common_setsockopt,
755         .getsockopt        = sock_common_getsockopt,
756         .sendmsg           = inet_sendmsg,
757         .recvmsg           = sock_common_recvmsg,
758         .mmap              = sock_no_mmap,
759         .sendpage          = sock_no_sendpage,
760 #ifdef CONFIG_COMPAT
761         .compat_setsockopt = compat_sock_common_setsockopt,
762         .compat_getsockopt = compat_sock_common_getsockopt,
763 #endif
764 };
765 
766 static struct inet_protosw l2tp_ip6_protosw = {
767         .type           = SOCK_DGRAM,
768         .protocol       = IPPROTO_L2TP,
769         .prot           = &l2tp_ip6_prot,
770         .ops            = &l2tp_ip6_ops,
771 };
772 
773 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
774         .handler        = l2tp_ip6_recv,
775 };
776 
777 static int __init l2tp_ip6_init(void)
778 {
779         int err;
780 
781         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
782 
783         err = proto_register(&l2tp_ip6_prot, 1);
784         if (err != 0)
785                 goto out;
786 
787         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
788         if (err)
789                 goto out1;
790 
791         inet6_register_protosw(&l2tp_ip6_protosw);
792         return 0;
793 
794 out1:
795         proto_unregister(&l2tp_ip6_prot);
796 out:
797         return err;
798 }
799 
800 static void __exit l2tp_ip6_exit(void)
801 {
802         inet6_unregister_protosw(&l2tp_ip6_protosw);
803         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
804         proto_unregister(&l2tp_ip6_prot);
805 }
806 
807 module_init(l2tp_ip6_init);
808 module_exit(l2tp_ip6_exit);
809 
810 MODULE_LICENSE("GPL");
811 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
812 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
813 MODULE_VERSION("1.0");
814 
815 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
816  * enums
817  */
818 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
819 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
820 

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