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 #include <net/net_namespace.h>
26 #include <net/netns/generic.h>
27
28 #include <net/transp_v6.h>
29 #include <net/addrconf.h>
30 #include <net/ip6_route.h>
31
32 #include "l2tp_core.h"
33
34 /* per-net private data for this module */
35 static unsigned int l2tp_ip6_net_id;
36 struct l2tp_ip6_net {
37 rwlock_t l2tp_ip6_lock;
38 struct hlist_head l2tp_ip6_table;
39 struct hlist_head l2tp_ip6_bind_table;
40 };
41
42 struct l2tp_ip6_sock {
43 /* inet_sock has to be the first member of l2tp_ip6_sock */
44 struct inet_sock inet;
45
46 u32 conn_id;
47 u32 peer_conn_id;
48
49 struct ipv6_pinfo inet6;
50 };
51
l2tp_ip6_sk(const struct sock * sk)52 static struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
53 {
54 return (struct l2tp_ip6_sock *)sk;
55 }
56
l2tp_ip6_pernet(const struct net * net)57 static struct l2tp_ip6_net *l2tp_ip6_pernet(const struct net *net)
58 {
59 return net_generic(net, l2tp_ip6_net_id);
60 }
61
__l2tp_ip6_bind_lookup(const struct net * net,const struct in6_addr * laddr,const struct in6_addr * raddr,int dif,u32 tunnel_id)62 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
63 const struct in6_addr *laddr,
64 const struct in6_addr *raddr,
65 int dif, u32 tunnel_id)
66 {
67 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
68 struct sock *sk;
69
70 sk_for_each_bound(sk, &pn->l2tp_ip6_bind_table) {
71 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
72 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
73 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
74 int bound_dev_if;
75
76 if (!net_eq(sock_net(sk), net))
77 continue;
78
79 bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
80 if (bound_dev_if && dif && bound_dev_if != dif)
81 continue;
82
83 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
84 !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
85 continue;
86
87 if (!ipv6_addr_any(sk_raddr) && raddr &&
88 !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
89 continue;
90
91 if (l2tp->conn_id != tunnel_id)
92 continue;
93
94 goto found;
95 }
96
97 sk = NULL;
98 found:
99 return sk;
100 }
101
102 /* When processing receive frames, there are two cases to
103 * consider. Data frames consist of a non-zero session-id and an
104 * optional cookie. Control frames consist of a regular L2TP header
105 * preceded by 32-bits of zeros.
106 *
107 * L2TPv3 Session Header Over IP
108 *
109 * 0 1 2 3
110 * 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
111 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112 * | Session ID |
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * | Cookie (optional, maximum 64 bits)...
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 *
119 * L2TPv3 Control Message Header Over IP
120 *
121 * 0 1 2 3
122 * 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
123 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
124 * | (32 bits of zeros) |
125 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
127 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
128 * | Control Connection ID |
129 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
130 * | Ns | Nr |
131 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
132 *
133 * All control frames are passed to userspace.
134 */
l2tp_ip6_recv(struct sk_buff * skb)135 static int l2tp_ip6_recv(struct sk_buff *skb)
136 {
137 struct net *net = dev_net(skb->dev);
138 struct l2tp_ip6_net *pn;
139 struct sock *sk;
140 u32 session_id;
141 u32 tunnel_id;
142 unsigned char *ptr, *optr;
143 struct l2tp_session *session;
144 struct l2tp_tunnel *tunnel = NULL;
145 struct ipv6hdr *iph;
146
147 pn = l2tp_ip6_pernet(net);
148
149 if (!pskb_may_pull(skb, 4))
150 goto discard;
151
152 /* Point to L2TP header */
153 optr = skb->data;
154 ptr = skb->data;
155 session_id = ntohl(*((__be32 *)ptr));
156 ptr += 4;
157
158 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
159 * the session_id. If it is 0, the packet is a L2TP control
160 * frame and the session_id value can be discarded.
161 */
162 if (session_id == 0) {
163 __skb_pull(skb, 4);
164 goto pass_up;
165 }
166
167 /* Ok, this is a data packet. Lookup the session. */
168 session = l2tp_v3_session_get(net, NULL, session_id);
169 if (!session)
170 goto discard;
171
172 tunnel = session->tunnel;
173 if (!tunnel)
174 goto discard_sess;
175
176 if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
177 goto discard_sess;
178
179 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
180 l2tp_session_put(session);
181
182 return 0;
183
184 pass_up:
185 /* Get the tunnel_id from the L2TP header */
186 if (!pskb_may_pull(skb, 12))
187 goto discard;
188
189 if ((skb->data[0] & 0xc0) != 0xc0)
190 goto discard;
191
192 tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
193 iph = ipv6_hdr(skb);
194
195 read_lock_bh(&pn->l2tp_ip6_lock);
196 sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
197 inet6_iif(skb), tunnel_id);
198 if (!sk) {
199 read_unlock_bh(&pn->l2tp_ip6_lock);
200 goto discard;
201 }
202 sock_hold(sk);
203 read_unlock_bh(&pn->l2tp_ip6_lock);
204
205 if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
206 goto discard_put;
207
208 nf_reset_ct(skb);
209
210 return sk_receive_skb(sk, skb, 1);
211
212 discard_sess:
213 l2tp_session_put(session);
214 goto discard;
215
216 discard_put:
217 sock_put(sk);
218
219 discard:
220 kfree_skb(skb);
221 return 0;
222 }
223
l2tp_ip6_hash(struct sock * sk)224 static int l2tp_ip6_hash(struct sock *sk)
225 {
226 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
227
228 if (sk_unhashed(sk)) {
229 write_lock_bh(&pn->l2tp_ip6_lock);
230 sk_add_node(sk, &pn->l2tp_ip6_table);
231 write_unlock_bh(&pn->l2tp_ip6_lock);
232 }
233 return 0;
234 }
235
l2tp_ip6_unhash(struct sock * sk)236 static void l2tp_ip6_unhash(struct sock *sk)
237 {
238 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
239
240 if (sk_unhashed(sk))
241 return;
242 write_lock_bh(&pn->l2tp_ip6_lock);
243 sk_del_node_init(sk);
244 write_unlock_bh(&pn->l2tp_ip6_lock);
245 }
246
l2tp_ip6_open(struct sock * sk)247 static int l2tp_ip6_open(struct sock *sk)
248 {
249 /* Prevent autobind. We don't have ports. */
250 inet_sk(sk)->inet_num = IPPROTO_L2TP;
251
252 l2tp_ip6_hash(sk);
253 return 0;
254 }
255
l2tp_ip6_close(struct sock * sk,long timeout)256 static void l2tp_ip6_close(struct sock *sk, long timeout)
257 {
258 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
259
260 write_lock_bh(&pn->l2tp_ip6_lock);
261 hlist_del_init(&sk->sk_bind_node);
262 sk_del_node_init(sk);
263 write_unlock_bh(&pn->l2tp_ip6_lock);
264
265 sk_common_release(sk);
266 }
267
l2tp_ip6_destroy_sock(struct sock * sk)268 static void l2tp_ip6_destroy_sock(struct sock *sk)
269 {
270 struct l2tp_tunnel *tunnel;
271
272 lock_sock(sk);
273 ip6_flush_pending_frames(sk);
274 release_sock(sk);
275
276 tunnel = l2tp_sk_to_tunnel(sk);
277 if (tunnel) {
278 l2tp_tunnel_delete(tunnel);
279 l2tp_tunnel_put(tunnel);
280 }
281 }
282
l2tp_ip6_bind(struct sock * sk,struct sockaddr * uaddr,int addr_len)283 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
284 {
285 struct inet_sock *inet = inet_sk(sk);
286 struct ipv6_pinfo *np = inet6_sk(sk);
287 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
288 struct net *net = sock_net(sk);
289 struct l2tp_ip6_net *pn;
290 __be32 v4addr = 0;
291 int bound_dev_if;
292 int addr_type;
293 int err;
294
295 pn = l2tp_ip6_pernet(net);
296
297 if (addr->l2tp_family != AF_INET6)
298 return -EINVAL;
299 if (addr_len < sizeof(*addr))
300 return -EINVAL;
301
302 addr_type = ipv6_addr_type(&addr->l2tp_addr);
303
304 /* l2tp_ip6 sockets are IPv6 only */
305 if (addr_type == IPV6_ADDR_MAPPED)
306 return -EADDRNOTAVAIL;
307
308 /* L2TP is point-point, not multicast */
309 if (addr_type & IPV6_ADDR_MULTICAST)
310 return -EADDRNOTAVAIL;
311
312 lock_sock(sk);
313
314 err = -EINVAL;
315 if (!sock_flag(sk, SOCK_ZAPPED))
316 goto out_unlock;
317
318 if (sk->sk_state != TCP_CLOSE)
319 goto out_unlock;
320
321 bound_dev_if = sk->sk_bound_dev_if;
322
323 /* Check if the address belongs to the host. */
324 rcu_read_lock();
325 if (addr_type != IPV6_ADDR_ANY) {
326 struct net_device *dev = NULL;
327
328 if (addr_type & IPV6_ADDR_LINKLOCAL) {
329 if (addr->l2tp_scope_id)
330 bound_dev_if = addr->l2tp_scope_id;
331
332 /* Binding to link-local address requires an
333 * interface.
334 */
335 if (!bound_dev_if)
336 goto out_unlock_rcu;
337
338 err = -ENODEV;
339 dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
340 if (!dev)
341 goto out_unlock_rcu;
342 }
343
344 /* ipv4 addr of the socket is invalid. Only the
345 * unspecified and mapped address have a v4 equivalent.
346 */
347 v4addr = LOOPBACK4_IPV6;
348 err = -EADDRNOTAVAIL;
349 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
350 goto out_unlock_rcu;
351 }
352 rcu_read_unlock();
353
354 write_lock_bh(&pn->l2tp_ip6_lock);
355 if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
356 addr->l2tp_conn_id)) {
357 write_unlock_bh(&pn->l2tp_ip6_lock);
358 err = -EADDRINUSE;
359 goto out_unlock;
360 }
361
362 inet->inet_saddr = v4addr;
363 inet->inet_rcv_saddr = v4addr;
364 sk->sk_bound_dev_if = bound_dev_if;
365 sk->sk_v6_rcv_saddr = addr->l2tp_addr;
366 np->saddr = addr->l2tp_addr;
367
368 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
369
370 sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
371 sk_del_node_init(sk);
372 write_unlock_bh(&pn->l2tp_ip6_lock);
373
374 sock_reset_flag(sk, SOCK_ZAPPED);
375 release_sock(sk);
376 return 0;
377
378 out_unlock_rcu:
379 rcu_read_unlock();
380 out_unlock:
381 release_sock(sk);
382
383 return err;
384 }
385
l2tp_ip6_connect(struct sock * sk,struct sockaddr * uaddr,int addr_len)386 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
387 int addr_len)
388 {
389 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
390 struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
391 struct in6_addr *daddr;
392 int addr_type;
393 int rc;
394 struct l2tp_ip6_net *pn;
395
396 if (addr_len < sizeof(*lsa))
397 return -EINVAL;
398
399 if (usin->sin6_family != AF_INET6)
400 return -EINVAL;
401
402 addr_type = ipv6_addr_type(&usin->sin6_addr);
403 if (addr_type & IPV6_ADDR_MULTICAST)
404 return -EINVAL;
405
406 if (addr_type & IPV6_ADDR_MAPPED) {
407 daddr = &usin->sin6_addr;
408 if (ipv4_is_multicast(daddr->s6_addr32[3]))
409 return -EINVAL;
410 }
411
412 lock_sock(sk);
413
414 /* Must bind first - autobinding does not work */
415 if (sock_flag(sk, SOCK_ZAPPED)) {
416 rc = -EINVAL;
417 goto out_sk;
418 }
419
420 rc = __ip6_datagram_connect(sk, uaddr, addr_len);
421 if (rc < 0)
422 goto out_sk;
423
424 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
425
426 pn = l2tp_ip6_pernet(sock_net(sk));
427 write_lock_bh(&pn->l2tp_ip6_lock);
428 hlist_del_init(&sk->sk_bind_node);
429 sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
430 write_unlock_bh(&pn->l2tp_ip6_lock);
431
432 out_sk:
433 release_sock(sk);
434
435 return rc;
436 }
437
l2tp_ip6_disconnect(struct sock * sk,int flags)438 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
439 {
440 if (sock_flag(sk, SOCK_ZAPPED))
441 return 0;
442
443 return __udp_disconnect(sk, flags);
444 }
445
l2tp_ip6_getname(struct socket * sock,struct sockaddr * uaddr,int peer)446 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
447 int peer)
448 {
449 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
450 struct sock *sk = sock->sk;
451 struct ipv6_pinfo *np = inet6_sk(sk);
452 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
453
454 lsa->l2tp_family = AF_INET6;
455 lsa->l2tp_flowinfo = 0;
456 lsa->l2tp_scope_id = 0;
457 lsa->l2tp_unused = 0;
458 if (peer) {
459 if (!lsk->peer_conn_id)
460 return -ENOTCONN;
461 lsa->l2tp_conn_id = lsk->peer_conn_id;
462 lsa->l2tp_addr = sk->sk_v6_daddr;
463 if (inet6_test_bit(SNDFLOW, sk))
464 lsa->l2tp_flowinfo = np->flow_label;
465 } else {
466 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
467 lsa->l2tp_addr = np->saddr;
468 else
469 lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
470
471 lsa->l2tp_conn_id = lsk->conn_id;
472 }
473 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
474 lsa->l2tp_scope_id = READ_ONCE(sk->sk_bound_dev_if);
475 return sizeof(*lsa);
476 }
477
l2tp_ip6_backlog_recv(struct sock * sk,struct sk_buff * skb)478 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
479 {
480 int rc;
481
482 /* Charge it to the socket, dropping if the queue is full. */
483 rc = sock_queue_rcv_skb(sk, skb);
484 if (rc < 0)
485 goto drop;
486
487 return 0;
488
489 drop:
490 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
491 kfree_skb(skb);
492 return -1;
493 }
494
l2tp_ip6_push_pending_frames(struct sock * sk)495 static int l2tp_ip6_push_pending_frames(struct sock *sk)
496 {
497 struct sk_buff *skb;
498 __be32 *transhdr = NULL;
499 int err = 0;
500
501 skb = skb_peek(&sk->sk_write_queue);
502 if (!skb)
503 goto out;
504
505 transhdr = (__be32 *)skb_transport_header(skb);
506 *transhdr = 0;
507
508 err = ip6_push_pending_frames(sk);
509
510 out:
511 return err;
512 }
513
514 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
515 * control frames.
516 */
l2tp_ip6_sendmsg(struct sock * sk,struct msghdr * msg,size_t len)517 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
518 {
519 struct ipv6_txoptions opt_space;
520 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
521 struct in6_addr *daddr, *final_p, final;
522 struct ipv6_pinfo *np = inet6_sk(sk);
523 struct ipv6_txoptions *opt_to_free = NULL;
524 struct ipv6_txoptions *opt = NULL;
525 struct ip6_flowlabel *flowlabel = NULL;
526 struct dst_entry *dst = NULL;
527 struct flowi6 fl6;
528 struct ipcm6_cookie ipc6;
529 int addr_len = msg->msg_namelen;
530 int transhdrlen = 4; /* zero session-id */
531 int ulen;
532 int err;
533
534 /* Rough check on arithmetic overflow,
535 * better check is made in ip6_append_data().
536 */
537 if (len > INT_MAX - transhdrlen)
538 return -EMSGSIZE;
539
540 /* Mirror BSD error message compatibility */
541 if (msg->msg_flags & MSG_OOB)
542 return -EOPNOTSUPP;
543
544 /* Get and verify the address */
545 memset(&fl6, 0, sizeof(fl6));
546
547 fl6.flowi6_mark = READ_ONCE(sk->sk_mark);
548 fl6.flowi6_uid = sk->sk_uid;
549
550 ipcm6_init_sk(&ipc6, sk);
551
552 if (lsa) {
553 if (addr_len < SIN6_LEN_RFC2133)
554 return -EINVAL;
555
556 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
557 return -EAFNOSUPPORT;
558
559 daddr = &lsa->l2tp_addr;
560 if (inet6_test_bit(SNDFLOW, sk)) {
561 fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
562 if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
563 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
564 if (IS_ERR(flowlabel))
565 return -EINVAL;
566 }
567 }
568
569 /* Otherwise it will be difficult to maintain
570 * sk->sk_dst_cache.
571 */
572 if (sk->sk_state == TCP_ESTABLISHED &&
573 ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
574 daddr = &sk->sk_v6_daddr;
575
576 if (addr_len >= sizeof(struct sockaddr_in6) &&
577 lsa->l2tp_scope_id &&
578 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
579 fl6.flowi6_oif = lsa->l2tp_scope_id;
580 } else {
581 if (sk->sk_state != TCP_ESTABLISHED)
582 return -EDESTADDRREQ;
583
584 daddr = &sk->sk_v6_daddr;
585 fl6.flowlabel = np->flow_label;
586 }
587
588 if (fl6.flowi6_oif == 0)
589 fl6.flowi6_oif = READ_ONCE(sk->sk_bound_dev_if);
590
591 if (msg->msg_controllen) {
592 opt = &opt_space;
593 memset(opt, 0, sizeof(struct ipv6_txoptions));
594 opt->tot_len = sizeof(struct ipv6_txoptions);
595 ipc6.opt = opt;
596
597 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
598 if (err < 0) {
599 fl6_sock_release(flowlabel);
600 return err;
601 }
602 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
603 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
604 if (IS_ERR(flowlabel))
605 return -EINVAL;
606 }
607 if (!(opt->opt_nflen | opt->opt_flen))
608 opt = NULL;
609 }
610
611 if (!opt) {
612 opt = txopt_get(np);
613 opt_to_free = opt;
614 }
615 if (flowlabel)
616 opt = fl6_merge_options(&opt_space, flowlabel, opt);
617 opt = ipv6_fixup_options(&opt_space, opt);
618 ipc6.opt = opt;
619
620 fl6.flowi6_proto = sk->sk_protocol;
621 if (!ipv6_addr_any(daddr))
622 fl6.daddr = *daddr;
623 else
624 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
625 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
626 fl6.saddr = np->saddr;
627
628 final_p = fl6_update_dst(&fl6, opt, &final);
629
630 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
631 fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
632 else if (!fl6.flowi6_oif)
633 fl6.flowi6_oif = READ_ONCE(np->ucast_oif);
634
635 security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
636
637 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
638
639 dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
640 if (IS_ERR(dst)) {
641 err = PTR_ERR(dst);
642 goto out;
643 }
644
645 if (ipc6.hlimit < 0)
646 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
647
648 if (msg->msg_flags & MSG_CONFIRM)
649 goto do_confirm;
650
651 back_from_confirm:
652 lock_sock(sk);
653 ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0);
654 err = ip6_append_data(sk, ip_generic_getfrag, msg,
655 ulen, transhdrlen, &ipc6,
656 &fl6, dst_rt6_info(dst),
657 msg->msg_flags);
658 if (err)
659 ip6_flush_pending_frames(sk);
660 else if (!(msg->msg_flags & MSG_MORE))
661 err = l2tp_ip6_push_pending_frames(sk);
662 release_sock(sk);
663 done:
664 dst_release(dst);
665 out:
666 fl6_sock_release(flowlabel);
667 txopt_put(opt_to_free);
668
669 return err < 0 ? err : len;
670
671 do_confirm:
672 if (msg->msg_flags & MSG_PROBE)
673 dst_confirm_neigh(dst, &fl6.daddr);
674 if (!(msg->msg_flags & MSG_PROBE) || len)
675 goto back_from_confirm;
676 err = 0;
677 goto done;
678 }
679
l2tp_ip6_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)680 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
681 int flags, int *addr_len)
682 {
683 struct ipv6_pinfo *np = inet6_sk(sk);
684 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
685 size_t copied = 0;
686 int err = -EOPNOTSUPP;
687 struct sk_buff *skb;
688
689 if (flags & MSG_OOB)
690 goto out;
691
692 if (flags & MSG_ERRQUEUE)
693 return ipv6_recv_error(sk, msg, len, addr_len);
694
695 skb = skb_recv_datagram(sk, flags, &err);
696 if (!skb)
697 goto out;
698
699 copied = skb->len;
700 if (len < copied) {
701 msg->msg_flags |= MSG_TRUNC;
702 copied = len;
703 }
704
705 err = skb_copy_datagram_msg(skb, 0, msg, copied);
706 if (err)
707 goto done;
708
709 sock_recv_timestamp(msg, sk, skb);
710
711 /* Copy the address. */
712 if (lsa) {
713 lsa->l2tp_family = AF_INET6;
714 lsa->l2tp_unused = 0;
715 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
716 lsa->l2tp_flowinfo = 0;
717 lsa->l2tp_scope_id = 0;
718 lsa->l2tp_conn_id = 0;
719 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
720 lsa->l2tp_scope_id = inet6_iif(skb);
721 *addr_len = sizeof(*lsa);
722 }
723
724 if (np->rxopt.all)
725 ip6_datagram_recv_ctl(sk, msg, skb);
726
727 if (flags & MSG_TRUNC)
728 copied = skb->len;
729 done:
730 skb_free_datagram(sk, skb);
731 out:
732 return err ? err : copied;
733 }
734
735 static struct proto l2tp_ip6_prot = {
736 .name = "L2TP/IPv6",
737 .owner = THIS_MODULE,
738 .init = l2tp_ip6_open,
739 .close = l2tp_ip6_close,
740 .bind = l2tp_ip6_bind,
741 .connect = l2tp_ip6_connect,
742 .disconnect = l2tp_ip6_disconnect,
743 .ioctl = l2tp_ioctl,
744 .destroy = l2tp_ip6_destroy_sock,
745 .setsockopt = ipv6_setsockopt,
746 .getsockopt = ipv6_getsockopt,
747 .sendmsg = l2tp_ip6_sendmsg,
748 .recvmsg = l2tp_ip6_recvmsg,
749 .backlog_rcv = l2tp_ip6_backlog_recv,
750 .hash = l2tp_ip6_hash,
751 .unhash = l2tp_ip6_unhash,
752 .obj_size = sizeof(struct l2tp_ip6_sock),
753 .ipv6_pinfo_offset = offsetof(struct l2tp_ip6_sock, inet6),
754 };
755
756 static const struct proto_ops l2tp_ip6_ops = {
757 .family = PF_INET6,
758 .owner = THIS_MODULE,
759 .release = inet6_release,
760 .bind = inet6_bind,
761 .connect = inet_dgram_connect,
762 .socketpair = sock_no_socketpair,
763 .accept = sock_no_accept,
764 .getname = l2tp_ip6_getname,
765 .poll = datagram_poll,
766 .ioctl = inet6_ioctl,
767 .gettstamp = sock_gettstamp,
768 .listen = sock_no_listen,
769 .shutdown = inet_shutdown,
770 .setsockopt = sock_common_setsockopt,
771 .getsockopt = sock_common_getsockopt,
772 .sendmsg = inet_sendmsg,
773 .recvmsg = sock_common_recvmsg,
774 .mmap = sock_no_mmap,
775 #ifdef CONFIG_COMPAT
776 .compat_ioctl = inet6_compat_ioctl,
777 #endif
778 };
779
780 static struct inet_protosw l2tp_ip6_protosw = {
781 .type = SOCK_DGRAM,
782 .protocol = IPPROTO_L2TP,
783 .prot = &l2tp_ip6_prot,
784 .ops = &l2tp_ip6_ops,
785 };
786
787 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
788 .handler = l2tp_ip6_recv,
789 };
790
l2tp_ip6_init_net(struct net * net)791 static __net_init int l2tp_ip6_init_net(struct net *net)
792 {
793 struct l2tp_ip6_net *pn = net_generic(net, l2tp_ip6_net_id);
794
795 rwlock_init(&pn->l2tp_ip6_lock);
796 INIT_HLIST_HEAD(&pn->l2tp_ip6_table);
797 INIT_HLIST_HEAD(&pn->l2tp_ip6_bind_table);
798 return 0;
799 }
800
l2tp_ip6_exit_net(struct net * net)801 static __net_exit void l2tp_ip6_exit_net(struct net *net)
802 {
803 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
804
805 write_lock_bh(&pn->l2tp_ip6_lock);
806 WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_table) != 0);
807 WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_bind_table) != 0);
808 write_unlock_bh(&pn->l2tp_ip6_lock);
809 }
810
811 static struct pernet_operations l2tp_ip6_net_ops = {
812 .init = l2tp_ip6_init_net,
813 .exit = l2tp_ip6_exit_net,
814 .id = &l2tp_ip6_net_id,
815 .size = sizeof(struct l2tp_ip6_net),
816 };
817
l2tp_ip6_init(void)818 static int __init l2tp_ip6_init(void)
819 {
820 int err;
821
822 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
823
824 err = register_pernet_device(&l2tp_ip6_net_ops);
825 if (err)
826 goto out;
827
828 err = proto_register(&l2tp_ip6_prot, 1);
829 if (err != 0)
830 goto out1;
831
832 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
833 if (err)
834 goto out2;
835
836 inet6_register_protosw(&l2tp_ip6_protosw);
837 return 0;
838
839 out2:
840 proto_unregister(&l2tp_ip6_prot);
841 out1:
842 unregister_pernet_device(&l2tp_ip6_net_ops);
843 out:
844 return err;
845 }
846
l2tp_ip6_exit(void)847 static void __exit l2tp_ip6_exit(void)
848 {
849 inet6_unregister_protosw(&l2tp_ip6_protosw);
850 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
851 proto_unregister(&l2tp_ip6_prot);
852 unregister_pernet_device(&l2tp_ip6_net_ops);
853 }
854
855 module_init(l2tp_ip6_init);
856 module_exit(l2tp_ip6_exit);
857
858 MODULE_LICENSE("GPL");
859 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
860 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
861 MODULE_VERSION("1.0");
862
863 /* Use the values of SOCK_DGRAM (2) as type and IPPROTO_L2TP (115) as protocol,
864 * because __stringify doesn't like enums
865 */
866 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 115, 2);
867 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, 115);
868