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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/tcp_states.h>
 29 #include <net/protocol.h>
 30 #include <net/xfrm.h>
 31 
 32 #include <net/transp_v6.h>
 33 #include <net/addrconf.h>
 34 #include <net/ip6_route.h>
 35 
 36 #include "l2tp_core.h"
 37 
 38 struct l2tp_ip6_sock {
 39         /* inet_sock has to be the first member of l2tp_ip6_sock */
 40         struct inet_sock        inet;
 41 
 42         u32                     conn_id;
 43         u32                     peer_conn_id;
 44 
 45         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
 46            inet6_sk_generic */
 47         struct ipv6_pinfo       inet6;
 48 };
 49 
 50 static DEFINE_RWLOCK(l2tp_ip6_lock);
 51 static struct hlist_head l2tp_ip6_table;
 52 static struct hlist_head l2tp_ip6_bind_table;
 53 
 54 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
 55 {
 56         return (struct l2tp_ip6_sock *)sk;
 57 }
 58 
 59 static struct sock *__l2tp_ip6_bind_lookup(struct net *net,
 60                                            struct in6_addr *laddr,
 61                                            int dif, u32 tunnel_id)
 62 {
 63         struct sock *sk;
 64 
 65         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
 66                 struct in6_addr *addr = inet6_rcv_saddr(sk);
 67                 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
 68 
 69                 if (l2tp == NULL)
 70                         continue;
 71 
 72                 if ((l2tp->conn_id == tunnel_id) &&
 73                     net_eq(sock_net(sk), net) &&
 74                     !(addr && ipv6_addr_equal(addr, laddr)) &&
 75                     !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
 76                         goto found;
 77         }
 78 
 79         sk = NULL;
 80 found:
 81         return sk;
 82 }
 83 
 84 static inline struct sock *l2tp_ip6_bind_lookup(struct net *net,
 85                                                 struct in6_addr *laddr,
 86                                                 int dif, u32 tunnel_id)
 87 {
 88         struct sock *sk = __l2tp_ip6_bind_lookup(net, laddr, dif, tunnel_id);
 89         if (sk)
 90                 sock_hold(sk);
 91 
 92         return sk;
 93 }
 94 
 95 /* When processing receive frames, there are two cases to
 96  * consider. Data frames consist of a non-zero session-id and an
 97  * optional cookie. Control frames consist of a regular L2TP header
 98  * preceded by 32-bits of zeros.
 99  *
100  * L2TPv3 Session Header Over IP
101  *
102  *  0                   1                   2                   3
103  *  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
104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105  * |                           Session ID                          |
106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107  * |               Cookie (optional, maximum 64 bits)...
108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109  *                                                                 |
110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
111  *
112  * L2TPv3 Control Message Header Over IP
113  *
114  *  0                   1                   2                   3
115  *  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
116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117  * |                      (32 bits of zeros)                       |
118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121  * |                     Control Connection ID                     |
122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
123  * |               Ns              |               Nr              |
124  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
125  *
126  * All control frames are passed to userspace.
127  */
128 static int l2tp_ip6_recv(struct sk_buff *skb)
129 {
130         struct sock *sk;
131         u32 session_id;
132         u32 tunnel_id;
133         unsigned char *ptr, *optr;
134         struct l2tp_session *session;
135         struct l2tp_tunnel *tunnel = NULL;
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_find(&init_net, NULL, session_id);
157         if (session == NULL)
158                 goto discard;
159 
160         tunnel = session->tunnel;
161         if (tunnel == NULL)
162                 goto discard;
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;
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         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
178                          tunnel->recv_payload_hook);
179         return 0;
180 
181 pass_up:
182         /* Get the tunnel_id from the L2TP header */
183         if (!pskb_may_pull(skb, 12))
184                 goto discard;
185 
186         if ((skb->data[0] & 0xc0) != 0xc0)
187                 goto discard;
188 
189         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
190         tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
191         if (tunnel != NULL)
192                 sk = tunnel->sock;
193         else {
194                 struct ipv6hdr *iph = ipv6_hdr(skb);
195 
196                 read_lock_bh(&l2tp_ip6_lock);
197                 sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr,
198                                             0, tunnel_id);
199                 read_unlock_bh(&l2tp_ip6_lock);
200         }
201 
202         if (sk == NULL)
203                 goto discard;
204 
205         sock_hold(sk);
206 
207         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
208                 goto discard_put;
209 
210         nf_reset(skb);
211 
212         return sk_receive_skb(sk, skb, 1);
213 
214 discard_put:
215         sock_put(sk);
216 
217 discard:
218         kfree_skb(skb);
219         return 0;
220 }
221 
222 static int l2tp_ip6_open(struct sock *sk)
223 {
224         /* Prevent autobind. We don't have ports. */
225         inet_sk(sk)->inet_num = IPPROTO_L2TP;
226 
227         write_lock_bh(&l2tp_ip6_lock);
228         sk_add_node(sk, &l2tp_ip6_table);
229         write_unlock_bh(&l2tp_ip6_lock);
230 
231         return 0;
232 }
233 
234 static void l2tp_ip6_close(struct sock *sk, long timeout)
235 {
236         write_lock_bh(&l2tp_ip6_lock);
237         hlist_del_init(&sk->sk_bind_node);
238         sk_del_node_init(sk);
239         write_unlock_bh(&l2tp_ip6_lock);
240 
241         sk_common_release(sk);
242 }
243 
244 static void l2tp_ip6_destroy_sock(struct sock *sk)
245 {
246         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
247 
248         lock_sock(sk);
249         ip6_flush_pending_frames(sk);
250         release_sock(sk);
251 
252         if (tunnel) {
253                 l2tp_tunnel_closeall(tunnel);
254                 sock_put(sk);
255         }
256 
257         inet6_destroy_sock(sk);
258 }
259 
260 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
261 {
262         struct inet_sock *inet = inet_sk(sk);
263         struct ipv6_pinfo *np = inet6_sk(sk);
264         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
265         __be32 v4addr = 0;
266         int addr_type;
267         int err;
268 
269         if (addr->l2tp_family != AF_INET6)
270                 return -EINVAL;
271         if (addr_len < sizeof(*addr))
272                 return -EINVAL;
273 
274         addr_type = ipv6_addr_type(&addr->l2tp_addr);
275 
276         /* l2tp_ip6 sockets are IPv6 only */
277         if (addr_type == IPV6_ADDR_MAPPED)
278                 return -EADDRNOTAVAIL;
279 
280         /* L2TP is point-point, not multicast */
281         if (addr_type & IPV6_ADDR_MULTICAST)
282                 return -EADDRNOTAVAIL;
283 
284         err = -EADDRINUSE;
285         read_lock_bh(&l2tp_ip6_lock);
286         if (__l2tp_ip6_bind_lookup(&init_net, &addr->l2tp_addr,
287                                    sk->sk_bound_dev_if, addr->l2tp_conn_id))
288                 goto out_in_use;
289         read_unlock_bh(&l2tp_ip6_lock);
290 
291         lock_sock(sk);
292 
293         err = -EINVAL;
294         if (!sock_flag(sk, SOCK_ZAPPED))
295                 goto out_unlock;
296 
297         if (sk->sk_state != TCP_CLOSE)
298                 goto out_unlock;
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_len >= sizeof(struct sockaddr_in6) &&
307                             addr->l2tp_scope_id) {
308                                 /* Override any existing binding, if another
309                                  * one is supplied by user.
310                                  */
311                                 sk->sk_bound_dev_if = addr->l2tp_scope_id;
312                         }
313 
314                         /* Binding to link-local address requires an
315                            interface */
316                         if (!sk->sk_bound_dev_if)
317                                 goto out_unlock_rcu;
318 
319                         err = -ENODEV;
320                         dev = dev_get_by_index_rcu(sock_net(sk),
321                                                    sk->sk_bound_dev_if);
322                         if (!dev)
323                                 goto out_unlock_rcu;
324                 }
325 
326                 /* ipv4 addr of the socket is invalid.  Only the
327                  * unspecified and mapped address have a v4 equivalent.
328                  */
329                 v4addr = LOOPBACK4_IPV6;
330                 err = -EADDRNOTAVAIL;
331                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
332                         goto out_unlock_rcu;
333         }
334         rcu_read_unlock();
335 
336         inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
337         np->rcv_saddr = addr->l2tp_addr;
338         np->saddr = addr->l2tp_addr;
339 
340         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
341 
342         write_lock_bh(&l2tp_ip6_lock);
343         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
344         sk_del_node_init(sk);
345         write_unlock_bh(&l2tp_ip6_lock);
346 
347         sock_reset_flag(sk, SOCK_ZAPPED);
348         release_sock(sk);
349         return 0;
350 
351 out_unlock_rcu:
352         rcu_read_unlock();
353 out_unlock:
354         release_sock(sk);
355         return err;
356 
357 out_in_use:
358         read_unlock_bh(&l2tp_ip6_lock);
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 (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
372                 return -EINVAL;
373 
374         if (addr_len < sizeof(*lsa))
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         rc = ip6_datagram_connect(sk, uaddr, addr_len);
388 
389         lock_sock(sk);
390 
391         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
392 
393         write_lock_bh(&l2tp_ip6_lock);
394         hlist_del_init(&sk->sk_bind_node);
395         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
396         write_unlock_bh(&l2tp_ip6_lock);
397 
398         release_sock(sk);
399 
400         return rc;
401 }
402 
403 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
404 {
405         if (sock_flag(sk, SOCK_ZAPPED))
406                 return 0;
407 
408         return udp_disconnect(sk, flags);
409 }
410 
411 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
412                             int *uaddr_len, int peer)
413 {
414         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
415         struct sock *sk = sock->sk;
416         struct ipv6_pinfo *np = inet6_sk(sk);
417         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
418 
419         lsa->l2tp_family = AF_INET6;
420         lsa->l2tp_flowinfo = 0;
421         lsa->l2tp_scope_id = 0;
422         lsa->l2tp_unused = 0;
423         if (peer) {
424                 if (!lsk->peer_conn_id)
425                         return -ENOTCONN;
426                 lsa->l2tp_conn_id = lsk->peer_conn_id;
427                 lsa->l2tp_addr = np->daddr;
428                 if (np->sndflow)
429                         lsa->l2tp_flowinfo = np->flow_label;
430         } else {
431                 if (ipv6_addr_any(&np->rcv_saddr))
432                         lsa->l2tp_addr = np->saddr;
433                 else
434                         lsa->l2tp_addr = np->rcv_saddr;
435 
436                 lsa->l2tp_conn_id = lsk->conn_id;
437         }
438         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
439                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
440         *uaddr_len = sizeof(*lsa);
441         return 0;
442 }
443 
444 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
445 {
446         int rc;
447 
448         /* Charge it to the socket, dropping if the queue is full. */
449         rc = sock_queue_rcv_skb(sk, skb);
450         if (rc < 0)
451                 goto drop;
452 
453         return 0;
454 
455 drop:
456         IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
457         kfree_skb(skb);
458         return -1;
459 }
460 
461 static int l2tp_ip6_push_pending_frames(struct sock *sk)
462 {
463         struct sk_buff *skb;
464         __be32 *transhdr = NULL;
465         int err = 0;
466 
467         skb = skb_peek(&sk->sk_write_queue);
468         if (skb == NULL)
469                 goto out;
470 
471         transhdr = (__be32 *)skb_transport_header(skb);
472         *transhdr = 0;
473 
474         err = ip6_push_pending_frames(sk);
475 
476 out:
477         return err;
478 }
479 
480 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
481  * control frames.
482  */
483 static int l2tp_ip6_sendmsg(struct kiocb *iocb, struct sock *sk,
484                             struct msghdr *msg, size_t len)
485 {
486         struct ipv6_txoptions opt_space;
487         struct sockaddr_l2tpip6 *lsa =
488                 (struct sockaddr_l2tpip6 *) msg->msg_name;
489         struct in6_addr *daddr, *final_p, final;
490         struct ipv6_pinfo *np = inet6_sk(sk);
491         struct ipv6_txoptions *opt_to_free = NULL;
492         struct ipv6_txoptions *opt = NULL;
493         struct ip6_flowlabel *flowlabel = NULL;
494         struct dst_entry *dst = NULL;
495         struct flowi6 fl6;
496         int addr_len = msg->msg_namelen;
497         int hlimit = -1;
498         int tclass = -1;
499         int dontfrag = -1;
500         int transhdrlen = 4; /* zero session-id */
501         int ulen = len + transhdrlen;
502         int err;
503 
504         /* Rough check on arithmetic overflow,
505            better check is made in ip6_append_data().
506          */
507         if (len > INT_MAX)
508                 return -EMSGSIZE;
509 
510         /* Mirror BSD error message compatibility */
511         if (msg->msg_flags & MSG_OOB)
512                 return -EOPNOTSUPP;
513 
514         /*
515          *      Get and verify the address.
516          */
517         memset(&fl6, 0, sizeof(fl6));
518 
519         fl6.flowi6_mark = sk->sk_mark;
520 
521         if (lsa) {
522                 if (addr_len < SIN6_LEN_RFC2133)
523                         return -EINVAL;
524 
525                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
526                         return -EAFNOSUPPORT;
527 
528                 daddr = &lsa->l2tp_addr;
529                 if (np->sndflow) {
530                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
531                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
532                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
533                                 if (flowlabel == NULL)
534                                         return -EINVAL;
535                                 daddr = &flowlabel->dst;
536                         }
537                 }
538 
539                 /*
540                  * Otherwise it will be difficult to maintain
541                  * sk->sk_dst_cache.
542                  */
543                 if (sk->sk_state == TCP_ESTABLISHED &&
544                     ipv6_addr_equal(daddr, &np->daddr))
545                         daddr = &np->daddr;
546 
547                 if (addr_len >= sizeof(struct sockaddr_in6) &&
548                     lsa->l2tp_scope_id &&
549                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
550                         fl6.flowi6_oif = lsa->l2tp_scope_id;
551         } else {
552                 if (sk->sk_state != TCP_ESTABLISHED)
553                         return -EDESTADDRREQ;
554 
555                 daddr = &np->daddr;
556                 fl6.flowlabel = np->flow_label;
557         }
558 
559         if (fl6.flowi6_oif == 0)
560                 fl6.flowi6_oif = sk->sk_bound_dev_if;
561 
562         if (msg->msg_controllen) {
563                 opt = &opt_space;
564                 memset(opt, 0, sizeof(struct ipv6_txoptions));
565                 opt->tot_len = sizeof(struct ipv6_txoptions);
566 
567                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
568                                             &hlimit, &tclass, &dontfrag);
569                 if (err < 0) {
570                         fl6_sock_release(flowlabel);
571                         return err;
572                 }
573                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
574                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
575                         if (flowlabel == NULL)
576                                 return -EINVAL;
577                 }
578                 if (!(opt->opt_nflen|opt->opt_flen))
579                         opt = NULL;
580         }
581 
582         if (!opt) {
583                 opt = txopt_get(np);
584                 opt_to_free = opt;
585         }
586         if (flowlabel)
587                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
588         opt = ipv6_fixup_options(&opt_space, opt);
589 
590         fl6.flowi6_proto = sk->sk_protocol;
591         if (!ipv6_addr_any(daddr))
592                 fl6.daddr = *daddr;
593         else
594                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
595         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
596                 fl6.saddr = np->saddr;
597 
598         final_p = fl6_update_dst(&fl6, opt, &final);
599 
600         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
601                 fl6.flowi6_oif = np->mcast_oif;
602         else if (!fl6.flowi6_oif)
603                 fl6.flowi6_oif = np->ucast_oif;
604 
605         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
606 
607         dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);
608         if (IS_ERR(dst)) {
609                 err = PTR_ERR(dst);
610                 goto out;
611         }
612 
613         if (hlimit < 0) {
614                 if (ipv6_addr_is_multicast(&fl6.daddr))
615                         hlimit = np->mcast_hops;
616                 else
617                         hlimit = np->hop_limit;
618                 if (hlimit < 0)
619                         hlimit = ip6_dst_hoplimit(dst);
620         }
621 
622         if (tclass < 0)
623                 tclass = np->tclass;
624 
625         if (dontfrag < 0)
626                 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->msg_iov,
634                               ulen, transhdrlen, hlimit, tclass, opt,
635                               &fl6, (struct rt6_info *)dst,
636                               msg->msg_flags, dontfrag);
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         dst_confirm(dst);
652         if (!(msg->msg_flags & MSG_PROBE) || len)
653                 goto back_from_confirm;
654         err = 0;
655         goto done;
656 }
657 
658 static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
659                             struct msghdr *msg, size_t len, int noblock,
660                             int flags, int *addr_len)
661 {
662         struct ipv6_pinfo *np = inet6_sk(sk);
663         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)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 (addr_len)
672                 *addr_len = sizeof(*lsa);
673 
674         if (flags & MSG_ERRQUEUE)
675                 return ipv6_recv_error(sk, msg, len, addr_len);
676 
677         skb = skb_recv_datagram(sk, flags, noblock, &err);
678         if (!skb)
679                 goto out;
680 
681         copied = skb->len;
682         if (len < copied) {
683                 msg->msg_flags |= MSG_TRUNC;
684                 copied = len;
685         }
686 
687         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
688         if (err)
689                 goto done;
690 
691         sock_recv_timestamp(msg, sk, skb);
692 
693         /* Copy the address. */
694         if (lsa) {
695                 lsa->l2tp_family = AF_INET6;
696                 lsa->l2tp_unused = 0;
697                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
698                 lsa->l2tp_flowinfo = 0;
699                 lsa->l2tp_scope_id = 0;
700                 lsa->l2tp_conn_id = 0;
701                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
702                         lsa->l2tp_scope_id = IP6CB(skb)->iif;
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              = inet_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         .listen            = sock_no_listen,
752         .shutdown          = inet_shutdown,
753         .setsockopt        = sock_common_setsockopt,
754         .getsockopt        = sock_common_getsockopt,
755         .sendmsg           = inet_sendmsg,
756         .recvmsg           = sock_common_recvmsg,
757         .mmap              = sock_no_mmap,
758         .sendpage          = sock_no_sendpage,
759 #ifdef CONFIG_COMPAT
760         .compat_setsockopt = compat_sock_common_setsockopt,
761         .compat_getsockopt = compat_sock_common_getsockopt,
762 #endif
763 };
764 
765 static struct inet_protosw l2tp_ip6_protosw = {
766         .type           = SOCK_DGRAM,
767         .protocol       = IPPROTO_L2TP,
768         .prot           = &l2tp_ip6_prot,
769         .ops            = &l2tp_ip6_ops,
770         .no_check       = 0,
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 

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