?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Linux 3.12.28
[linux/fpc-iii.git] / net / l2tp / l2tp_core.c
blobb076e8309bc2722885c27108316634f064cb44ff
1 /*
2 * L2TP core.
3 *
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5 *
6 * This file contains some code of the original L2TPv2 pppol2tp
7 * driver, which has the following copyright:
8 *
9 * Authors: Martijn van Oosterhout <kleptog@svana.org>
10 * James Chapman (jchapman@katalix.com)
11 * Contributors:
12 * Michal Ostrowski <mostrows@speakeasy.net>
13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
14 * David S. Miller (davem@redhat.com)
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License version 2 as
18 * published by the Free Software Foundation.
19 */
20
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23 #include <linux/module.h>
24 #include <linux/string.h>
25 #include <linux/list.h>
26 #include <linux/rculist.h>
27 #include <linux/uaccess.h>
28
29 #include <linux/kernel.h>
30 #include <linux/spinlock.h>
31 #include <linux/kthread.h>
32 #include <linux/sched.h>
33 #include <linux/slab.h>
34 #include <linux/errno.h>
35 #include <linux/jiffies.h>
36
37 #include <linux/netdevice.h>
38 #include <linux/net.h>
39 #include <linux/inetdevice.h>
40 #include <linux/skbuff.h>
41 #include <linux/init.h>
42 #include <linux/in.h>
43 #include <linux/ip.h>
44 #include <linux/udp.h>
45 #include <linux/l2tp.h>
46 #include <linux/hash.h>
47 #include <linux/sort.h>
48 #include <linux/file.h>
49 #include <linux/nsproxy.h>
50 #include <net/net_namespace.h>
51 #include <net/netns/generic.h>
52 #include <net/dst.h>
53 #include <net/ip.h>
54 #include <net/udp.h>
55 #include <net/inet_common.h>
56 #include <net/xfrm.h>
57 #include <net/protocol.h>
58 #include <net/inet6_connection_sock.h>
59 #include <net/inet_ecn.h>
60 #include <net/ip6_route.h>
61 #include <net/ip6_checksum.h>
62
63 #include <asm/byteorder.h>
64 #include <linux/atomic.h>
65
66 #include "l2tp_core.h"
67
68 #define L2TP_DRV_VERSION "V2.0"
69
70 /* L2TP header constants */
71 #define L2TP_HDRFLAG_T 0x8000
72 #define L2TP_HDRFLAG_L 0x4000
73 #define L2TP_HDRFLAG_S 0x0800
74 #define L2TP_HDRFLAG_O 0x0200
75 #define L2TP_HDRFLAG_P 0x0100
76
77 #define L2TP_HDR_VER_MASK 0x000F
78 #define L2TP_HDR_VER_2 0x0002
79 #define L2TP_HDR_VER_3 0x0003
80
81 /* L2TPv3 default L2-specific sublayer */
82 #define L2TP_SLFLAG_S 0x40000000
83 #define L2TP_SL_SEQ_MASK 0x00ffffff
84
85 #define L2TP_HDR_SIZE_SEQ 10
86 #define L2TP_HDR_SIZE_NOSEQ 6
87
88 /* Default trace flags */
89 #define L2TP_DEFAULT_DEBUG_FLAGS 0
90
91 /* Private data stored for received packets in the skb.
92 */
93 struct l2tp_skb_cb {
94 u32 ns;
95 u16 has_seq;
96 u16 length;
97 unsigned long expires;
98 };
99
100 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
101
102 static atomic_t l2tp_tunnel_count;
103 static atomic_t l2tp_session_count;
104 static struct workqueue_struct *l2tp_wq;
105
106 /* per-net private data for this module */
107 static unsigned int l2tp_net_id;
108 struct l2tp_net {
109 struct list_head l2tp_tunnel_list;
110 spinlock_t l2tp_tunnel_list_lock;
111 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
112 spinlock_t l2tp_session_hlist_lock;
113 };
114
115 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
116 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
117
118 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
119 {
120 return sk->sk_user_data;
121 }
122
123 static inline struct l2tp_net *l2tp_pernet(struct net *net)
124 {
125 BUG_ON(!net);
126
127 return net_generic(net, l2tp_net_id);
128 }
129
130 /* Tunnel reference counts. Incremented per session that is added to
131 * the tunnel.
132 */
133 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
134 {
135 atomic_inc(&tunnel->ref_count);
136 }
137
138 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
139 {
140 if (atomic_dec_and_test(&tunnel->ref_count))
141 l2tp_tunnel_free(tunnel);
142 }
143 #ifdef L2TP_REFCNT_DEBUG
144 #define l2tp_tunnel_inc_refcount(_t) \
145 do { \
146 pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", \
147 __func__, __LINE__, (_t)->name, \
148 atomic_read(&_t->ref_count)); \
149 l2tp_tunnel_inc_refcount_1(_t); \
150 } while (0)
151 #define l2tp_tunnel_dec_refcount(_t)
152 do { \
153 pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", \
154 __func__, __LINE__, (_t)->name, \
155 atomic_read(&_t->ref_count)); \
156 l2tp_tunnel_dec_refcount_1(_t); \
157 } while (0)
158 #else
159 #define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
160 #define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
161 #endif
162
163 /* Session hash global list for L2TPv3.
164 * The session_id SHOULD be random according to RFC3931, but several
165 * L2TP implementations use incrementing session_ids. So we do a real
166 * hash on the session_id, rather than a simple bitmask.
167 */
168 static inline struct hlist_head *
169 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
170 {
171 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
172
173 }
174
175 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
176 * owned by userspace. A struct sock returned from this function must be
177 * released using l2tp_tunnel_sock_put once you're done with it.
178 */
179 struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
180 {
181 int err = 0;
182 struct socket *sock = NULL;
183 struct sock *sk = NULL;
184
185 if (!tunnel)
186 goto out;
187
188 if (tunnel->fd >= 0) {
189 /* Socket is owned by userspace, who might be in the process
190 * of closing it. Look the socket up using the fd to ensure
191 * consistency.
192 */
193 sock = sockfd_lookup(tunnel->fd, &err);
194 if (sock)
195 sk = sock->sk;
196 } else {
197 /* Socket is owned by kernelspace */
198 sk = tunnel->sock;
199 sock_hold(sk);
200 }
201
202 out:
203 return sk;
204 }
205 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_lookup);
206
207 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
208 void l2tp_tunnel_sock_put(struct sock *sk)
209 {
210 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
211 if (tunnel) {
212 if (tunnel->fd >= 0) {
213 /* Socket is owned by userspace */
214 sockfd_put(sk->sk_socket);
215 }
216 sock_put(sk);
217 }
218 sock_put(sk);
219 }
220 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_put);
221
222 /* Lookup a session by id in the global session list
223 */
224 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
225 {
226 struct l2tp_net *pn = l2tp_pernet(net);
227 struct hlist_head *session_list =
228 l2tp_session_id_hash_2(pn, session_id);
229 struct l2tp_session *session;
230
231 rcu_read_lock_bh();
232 hlist_for_each_entry_rcu(session, session_list, global_hlist) {
233 if (session->session_id == session_id) {
234 rcu_read_unlock_bh();
235 return session;
236 }
237 }
238 rcu_read_unlock_bh();
239
240 return NULL;
241 }
242
243 /* Session hash list.
244 * The session_id SHOULD be random according to RFC2661, but several
245 * L2TP implementations (Cisco and Microsoft) use incrementing
246 * session_ids. So we do a real hash on the session_id, rather than a
247 * simple bitmask.
248 */
249 static inline struct hlist_head *
250 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
251 {
252 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
253 }
254
255 /* Lookup a session by id
256 */
257 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
258 {
259 struct hlist_head *session_list;
260 struct l2tp_session *session;
261
262 /* In L2TPv3, session_ids are unique over all tunnels and we
263 * sometimes need to look them up before we know the
264 * tunnel.
265 */
266 if (tunnel == NULL)
267 return l2tp_session_find_2(net, session_id);
268
269 session_list = l2tp_session_id_hash(tunnel, session_id);
270 read_lock_bh(&tunnel->hlist_lock);
271 hlist_for_each_entry(session, session_list, hlist) {
272 if (session->session_id == session_id) {
273 read_unlock_bh(&tunnel->hlist_lock);
274 return session;
275 }
276 }
277 read_unlock_bh(&tunnel->hlist_lock);
278
279 return NULL;
280 }
281 EXPORT_SYMBOL_GPL(l2tp_session_find);
282
283 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
284 {
285 int hash;
286 struct l2tp_session *session;
287 int count = 0;
288
289 read_lock_bh(&tunnel->hlist_lock);
290 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
291 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
292 if (++count > nth) {
293 read_unlock_bh(&tunnel->hlist_lock);
294 return session;
295 }
296 }
297 }
298
299 read_unlock_bh(&tunnel->hlist_lock);
300
301 return NULL;
302 }
303 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
304
305 /* Lookup a session by interface name.
306 * This is very inefficient but is only used by management interfaces.
307 */
308 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
309 {
310 struct l2tp_net *pn = l2tp_pernet(net);
311 int hash;
312 struct l2tp_session *session;
313
314 rcu_read_lock_bh();
315 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
316 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
317 if (!strcmp(session->ifname, ifname)) {
318 rcu_read_unlock_bh();
319 return session;
320 }
321 }
322 }
323
324 rcu_read_unlock_bh();
325
326 return NULL;
327 }
328 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
329
330 /* Lookup a tunnel by id
331 */
332 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
333 {
334 struct l2tp_tunnel *tunnel;
335 struct l2tp_net *pn = l2tp_pernet(net);
336
337 rcu_read_lock_bh();
338 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
339 if (tunnel->tunnel_id == tunnel_id) {
340 rcu_read_unlock_bh();
341 return tunnel;
342 }
343 }
344 rcu_read_unlock_bh();
345
346 return NULL;
347 }
348 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
349
350 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
351 {
352 struct l2tp_net *pn = l2tp_pernet(net);
353 struct l2tp_tunnel *tunnel;
354 int count = 0;
355
356 rcu_read_lock_bh();
357 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
358 if (++count > nth) {
359 rcu_read_unlock_bh();
360 return tunnel;
361 }
362 }
363
364 rcu_read_unlock_bh();
365
366 return NULL;
367 }
368 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
369
370 /*****************************************************************************
371 * Receive data handling
372 *****************************************************************************/
373
374 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
375 * number.
376 */
377 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
378 {
379 struct sk_buff *skbp;
380 struct sk_buff *tmp;
381 u32 ns = L2TP_SKB_CB(skb)->ns;
382
383 spin_lock_bh(&session->reorder_q.lock);
384 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
385 if (L2TP_SKB_CB(skbp)->ns > ns) {
386 __skb_queue_before(&session->reorder_q, skbp, skb);
387 l2tp_dbg(session, L2TP_MSG_SEQ,
388 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
389 session->name, ns, L2TP_SKB_CB(skbp)->ns,
390 skb_queue_len(&session->reorder_q));
391 atomic_long_inc(&session->stats.rx_oos_packets);
392 goto out;
393 }
394 }
395
396 __skb_queue_tail(&session->reorder_q, skb);
397
398 out:
399 spin_unlock_bh(&session->reorder_q.lock);
400 }
401
402 /* Dequeue a single skb.
403 */
404 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
405 {
406 struct l2tp_tunnel *tunnel = session->tunnel;
407 int length = L2TP_SKB_CB(skb)->length;
408
409 /* We're about to requeue the skb, so return resources
410 * to its current owner (a socket receive buffer).
411 */
412 skb_orphan(skb);
413
414 atomic_long_inc(&tunnel->stats.rx_packets);
415 atomic_long_add(length, &tunnel->stats.rx_bytes);
416 atomic_long_inc(&session->stats.rx_packets);
417 atomic_long_add(length, &session->stats.rx_bytes);
418
419 if (L2TP_SKB_CB(skb)->has_seq) {
420 /* Bump our Nr */
421 session->nr++;
422 session->nr &= session->nr_max;
423
424 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
425 session->name, session->nr);
426 }
427
428 /* call private receive handler */
429 if (session->recv_skb != NULL)
430 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
431 else
432 kfree_skb(skb);
433
434 if (session->deref)
435 (*session->deref)(session);
436 }
437
438 /* Dequeue skbs from the session's reorder_q, subject to packet order.
439 * Skbs that have been in the queue for too long are simply discarded.
440 */
441 static void l2tp_recv_dequeue(struct l2tp_session *session)
442 {
443 struct sk_buff *skb;
444 struct sk_buff *tmp;
445
446 /* If the pkt at the head of the queue has the nr that we
447 * expect to send up next, dequeue it and any other
448 * in-sequence packets behind it.
449 */
450 start:
451 spin_lock_bh(&session->reorder_q.lock);
452 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
453 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
454 atomic_long_inc(&session->stats.rx_seq_discards);
455 atomic_long_inc(&session->stats.rx_errors);
456 l2tp_dbg(session, L2TP_MSG_SEQ,
457 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
458 session->name, L2TP_SKB_CB(skb)->ns,
459 L2TP_SKB_CB(skb)->length, session->nr,
460 skb_queue_len(&session->reorder_q));
461 session->reorder_skip = 1;
462 __skb_unlink(skb, &session->reorder_q);
463 kfree_skb(skb);
464 if (session->deref)
465 (*session->deref)(session);
466 continue;
467 }
468
469 if (L2TP_SKB_CB(skb)->has_seq) {
470 if (session->reorder_skip) {
471 l2tp_dbg(session, L2TP_MSG_SEQ,
472 "%s: advancing nr to next pkt: %u -> %u",
473 session->name, session->nr,
474 L2TP_SKB_CB(skb)->ns);
475 session->reorder_skip = 0;
476 session->nr = L2TP_SKB_CB(skb)->ns;
477 }
478 if (L2TP_SKB_CB(skb)->ns != session->nr) {
479 l2tp_dbg(session, L2TP_MSG_SEQ,
480 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
481 session->name, L2TP_SKB_CB(skb)->ns,
482 L2TP_SKB_CB(skb)->length, session->nr,
483 skb_queue_len(&session->reorder_q));
484 goto out;
485 }
486 }
487 __skb_unlink(skb, &session->reorder_q);
488
489 /* Process the skb. We release the queue lock while we
490 * do so to let other contexts process the queue.
491 */
492 spin_unlock_bh(&session->reorder_q.lock);
493 l2tp_recv_dequeue_skb(session, skb);
494 goto start;
495 }
496
497 out:
498 spin_unlock_bh(&session->reorder_q.lock);
499 }
500
501 static inline int l2tp_verify_udp_checksum(struct sock *sk,
502 struct sk_buff *skb)
503 {
504 struct udphdr *uh = udp_hdr(skb);
505 u16 ulen = ntohs(uh->len);
506 __wsum psum;
507
508 if (sk->sk_no_check || skb_csum_unnecessary(skb))
509 return 0;
510
511 #if IS_ENABLED(CONFIG_IPV6)
512 if (sk->sk_family == PF_INET6 && !l2tp_tunnel(sk)->v4mapped) {
513 if (!uh->check) {
514 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
515 return 1;
516 }
517 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
518 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
519 &ipv6_hdr(skb)->daddr, ulen,
520 IPPROTO_UDP, skb->csum)) {
521 skb->ip_summed = CHECKSUM_UNNECESSARY;
522 return 0;
523 }
524 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
525 &ipv6_hdr(skb)->daddr,
526 skb->len, IPPROTO_UDP,
527 0));
528 } else
529 #endif
530 {
531 struct inet_sock *inet;
532 if (!uh->check)
533 return 0;
534 inet = inet_sk(sk);
535 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
536 ulen, IPPROTO_UDP, 0);
537
538 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
539 !csum_fold(csum_add(psum, skb->csum)))
540 return 0;
541 skb->csum = psum;
542 }
543
544 return __skb_checksum_complete(skb);
545 }
546
547 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
548 {
549 u32 nws;
550
551 if (nr >= session->nr)
552 nws = nr - session->nr;
553 else
554 nws = (session->nr_max + 1) - (session->nr - nr);
555
556 return nws < session->nr_window_size;
557 }
558
559 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
560 * acceptable, else non-zero.
561 */
562 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
563 {
564 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
565 /* Packet sequence number is outside allowed window.
566 * Discard it.
567 */
568 l2tp_dbg(session, L2TP_MSG_SEQ,
569 "%s: pkt %u len %d discarded, outside window, nr=%u\n",
570 session->name, L2TP_SKB_CB(skb)->ns,
571 L2TP_SKB_CB(skb)->length, session->nr);
572 goto discard;
573 }
574
575 if (session->reorder_timeout != 0) {
576 /* Packet reordering enabled. Add skb to session's
577 * reorder queue, in order of ns.
578 */
579 l2tp_recv_queue_skb(session, skb);
580 goto out;
581 }
582
583 /* Packet reordering disabled. Discard out-of-sequence packets, while
584 * tracking the number if in-sequence packets after the first OOS packet
585 * is seen. After nr_oos_count_max in-sequence packets, reset the
586 * sequence number to re-enable packet reception.
587 */
588 if (L2TP_SKB_CB(skb)->ns == session->nr) {
589 skb_queue_tail(&session->reorder_q, skb);
590 } else {
591 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
592 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
593
594 if (nr_oos == nr_next)
595 session->nr_oos_count++;
596 else
597 session->nr_oos_count = 0;
598
599 session->nr_oos = nr_oos;
600 if (session->nr_oos_count > session->nr_oos_count_max) {
601 session->reorder_skip = 1;
602 l2tp_dbg(session, L2TP_MSG_SEQ,
603 "%s: %d oos packets received. Resetting sequence numbers\n",
604 session->name, session->nr_oos_count);
605 }
606 if (!session->reorder_skip) {
607 atomic_long_inc(&session->stats.rx_seq_discards);
608 l2tp_dbg(session, L2TP_MSG_SEQ,
609 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
610 session->name, L2TP_SKB_CB(skb)->ns,
611 L2TP_SKB_CB(skb)->length, session->nr,
612 skb_queue_len(&session->reorder_q));
613 goto discard;
614 }
615 skb_queue_tail(&session->reorder_q, skb);
616 }
617
618 out:
619 return 0;
620
621 discard:
622 return 1;
623 }
624
625 /* Do receive processing of L2TP data frames. We handle both L2TPv2
626 * and L2TPv3 data frames here.
627 *
628 * L2TPv2 Data Message Header
629 *
630 * 0 1 2 3
631 * 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
632 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
633 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
634 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
635 * | Tunnel ID | Session ID |
636 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
637 * | Ns (opt) | Nr (opt) |
638 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
639 * | Offset Size (opt) | Offset pad... (opt)
640 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
641 *
642 * Data frames are marked by T=0. All other fields are the same as
643 * those in L2TP control frames.
644 *
645 * L2TPv3 Data Message Header
646 *
647 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
648 * | L2TP Session Header |
649 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
650 * | L2-Specific Sublayer |
651 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
652 * | Tunnel Payload ...
653 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
654 *
655 * L2TPv3 Session Header Over IP
656 *
657 * 0 1 2 3
658 * 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
659 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
660 * | Session ID |
661 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
662 * | Cookie (optional, maximum 64 bits)...
663 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
664 * |
665 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
666 *
667 * L2TPv3 L2-Specific Sublayer Format
668 *
669 * 0 1 2 3
670 * 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
671 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
672 * |x|S|x|x|x|x|x|x| Sequence Number |
673 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
674 *
675 * Cookie value, sublayer format and offset (pad) are negotiated with
676 * the peer when the session is set up. Unlike L2TPv2, we do not need
677 * to parse the packet header to determine if optional fields are
678 * present.
679 *
680 * Caller must already have parsed the frame and determined that it is
681 * a data (not control) frame before coming here. Fields up to the
682 * session-id have already been parsed and ptr points to the data
683 * after the session-id.
684 */
685 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
686 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
687 int length, int (*payload_hook)(struct sk_buff *skb))
688 {
689 struct l2tp_tunnel *tunnel = session->tunnel;
690 int offset;
691 u32 ns, nr;
692
693 /* The ref count is increased since we now hold a pointer to
694 * the session. Take care to decrement the refcnt when exiting
695 * this function from now on...
696 */
697 l2tp_session_inc_refcount(session);
698 if (session->ref)
699 (*session->ref)(session);
700
701 /* Parse and check optional cookie */
702 if (session->peer_cookie_len > 0) {
703 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
704 l2tp_info(tunnel, L2TP_MSG_DATA,
705 "%s: cookie mismatch (%u/%u). Discarding.\n",
706 tunnel->name, tunnel->tunnel_id,
707 session->session_id);
708 atomic_long_inc(&session->stats.rx_cookie_discards);
709 goto discard;
710 }
711 ptr += session->peer_cookie_len;
712 }
713
714 /* Handle the optional sequence numbers. Sequence numbers are
715 * in different places for L2TPv2 and L2TPv3.
716 *
717 * If we are the LAC, enable/disable sequence numbers under
718 * the control of the LNS. If no sequence numbers present but
719 * we were expecting them, discard frame.
720 */
721 ns = nr = 0;
722 L2TP_SKB_CB(skb)->has_seq = 0;
723 if (tunnel->version == L2TP_HDR_VER_2) {
724 if (hdrflags & L2TP_HDRFLAG_S) {
725 ns = ntohs(*(__be16 *) ptr);
726 ptr += 2;
727 nr = ntohs(*(__be16 *) ptr);
728 ptr += 2;
729
730 /* Store L2TP info in the skb */
731 L2TP_SKB_CB(skb)->ns = ns;
732 L2TP_SKB_CB(skb)->has_seq = 1;
733
734 l2tp_dbg(session, L2TP_MSG_SEQ,
735 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
736 session->name, ns, nr, session->nr);
737 }
738 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
739 u32 l2h = ntohl(*(__be32 *) ptr);
740
741 if (l2h & 0x40000000) {
742 ns = l2h & 0x00ffffff;
743
744 /* Store L2TP info in the skb */
745 L2TP_SKB_CB(skb)->ns = ns;
746 L2TP_SKB_CB(skb)->has_seq = 1;
747
748 l2tp_dbg(session, L2TP_MSG_SEQ,
749 "%s: recv data ns=%u, session nr=%u\n",
750 session->name, ns, session->nr);
751 }
752 }
753
754 /* Advance past L2-specific header, if present */
755 ptr += session->l2specific_len;
756
757 if (L2TP_SKB_CB(skb)->has_seq) {
758 /* Received a packet with sequence numbers. If we're the LNS,
759 * check if we sre sending sequence numbers and if not,
760 * configure it so.
761 */
762 if ((!session->lns_mode) && (!session->send_seq)) {
763 l2tp_info(session, L2TP_MSG_SEQ,
764 "%s: requested to enable seq numbers by LNS\n",
765 session->name);
766 session->send_seq = -1;
767 l2tp_session_set_header_len(session, tunnel->version);
768 }
769 } else {
770 /* No sequence numbers.
771 * If user has configured mandatory sequence numbers, discard.
772 */
773 if (session->recv_seq) {
774 l2tp_warn(session, L2TP_MSG_SEQ,
775 "%s: recv data has no seq numbers when required. Discarding.\n",
776 session->name);
777 atomic_long_inc(&session->stats.rx_seq_discards);
778 goto discard;
779 }
780
781 /* If we're the LAC and we're sending sequence numbers, the
782 * LNS has requested that we no longer send sequence numbers.
783 * If we're the LNS and we're sending sequence numbers, the
784 * LAC is broken. Discard the frame.
785 */
786 if ((!session->lns_mode) && (session->send_seq)) {
787 l2tp_info(session, L2TP_MSG_SEQ,
788 "%s: requested to disable seq numbers by LNS\n",
789 session->name);
790 session->send_seq = 0;
791 l2tp_session_set_header_len(session, tunnel->version);
792 } else if (session->send_seq) {
793 l2tp_warn(session, L2TP_MSG_SEQ,
794 "%s: recv data has no seq numbers when required. Discarding.\n",
795 session->name);
796 atomic_long_inc(&session->stats.rx_seq_discards);
797 goto discard;
798 }
799 }
800
801 /* Session data offset is handled differently for L2TPv2 and
802 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
803 * the header. For L2TPv3, the offset is negotiated using AVPs
804 * in the session setup control protocol.
805 */
806 if (tunnel->version == L2TP_HDR_VER_2) {
807 /* If offset bit set, skip it. */
808 if (hdrflags & L2TP_HDRFLAG_O) {
809 offset = ntohs(*(__be16 *)ptr);
810 ptr += 2 + offset;
811 }
812 } else
813 ptr += session->offset;
814
815 offset = ptr - optr;
816 if (!pskb_may_pull(skb, offset))
817 goto discard;
818
819 __skb_pull(skb, offset);
820
821 /* If caller wants to process the payload before we queue the
822 * packet, do so now.
823 */
824 if (payload_hook)
825 if ((*payload_hook)(skb))
826 goto discard;
827
828 /* Prepare skb for adding to the session's reorder_q. Hold
829 * packets for max reorder_timeout or 1 second if not
830 * reordering.
831 */
832 L2TP_SKB_CB(skb)->length = length;
833 L2TP_SKB_CB(skb)->expires = jiffies +
834 (session->reorder_timeout ? session->reorder_timeout : HZ);
835
836 /* Add packet to the session's receive queue. Reordering is done here, if
837 * enabled. Saved L2TP protocol info is stored in skb->sb[].
838 */
839 if (L2TP_SKB_CB(skb)->has_seq) {
840 if (l2tp_recv_data_seq(session, skb))
841 goto discard;
842 } else {
843 /* No sequence numbers. Add the skb to the tail of the
844 * reorder queue. This ensures that it will be
845 * delivered after all previous sequenced skbs.
846 */
847 skb_queue_tail(&session->reorder_q, skb);
848 }
849
850 /* Try to dequeue as many skbs from reorder_q as we can. */
851 l2tp_recv_dequeue(session);
852
853 l2tp_session_dec_refcount(session);
854
855 return;
856
857 discard:
858 atomic_long_inc(&session->stats.rx_errors);
859 kfree_skb(skb);
860
861 if (session->deref)
862 (*session->deref)(session);
863
864 l2tp_session_dec_refcount(session);
865 }
866 EXPORT_SYMBOL(l2tp_recv_common);
867
868 /* Drop skbs from the session's reorder_q
869 */
870 int l2tp_session_queue_purge(struct l2tp_session *session)
871 {
872 struct sk_buff *skb = NULL;
873 BUG_ON(!session);
874 BUG_ON(session->magic != L2TP_SESSION_MAGIC);
875 while ((skb = skb_dequeue(&session->reorder_q))) {
876 atomic_long_inc(&session->stats.rx_errors);
877 kfree_skb(skb);
878 if (session->deref)
879 (*session->deref)(session);
880 }
881 return 0;
882 }
883 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
884
885 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
886 * here. The skb is not on a list when we get here.
887 * Returns 0 if the packet was a data packet and was successfully passed on.
888 * Returns 1 if the packet was not a good data packet and could not be
889 * forwarded. All such packets are passed up to userspace to deal with.
890 */
891 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
892 int (*payload_hook)(struct sk_buff *skb))
893 {
894 struct l2tp_session *session = NULL;
895 unsigned char *ptr, *optr;
896 u16 hdrflags;
897 u32 tunnel_id, session_id;
898 u16 version;
899 int length;
900
901 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
902 goto discard_bad_csum;
903
904 /* UDP always verifies the packet length. */
905 __skb_pull(skb, sizeof(struct udphdr));
906
907 /* Short packet? */
908 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
909 l2tp_info(tunnel, L2TP_MSG_DATA,
910 "%s: recv short packet (len=%d)\n",
911 tunnel->name, skb->len);
912 goto error;
913 }
914
915 /* Trace packet contents, if enabled */
916 if (tunnel->debug & L2TP_MSG_DATA) {
917 length = min(32u, skb->len);
918 if (!pskb_may_pull(skb, length))
919 goto error;
920
921 pr_debug("%s: recv\n", tunnel->name);
922 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
923 }
924
925 /* Point to L2TP header */
926 optr = ptr = skb->data;
927
928 /* Get L2TP header flags */
929 hdrflags = ntohs(*(__be16 *) ptr);
930
931 /* Check protocol version */
932 version = hdrflags & L2TP_HDR_VER_MASK;
933 if (version != tunnel->version) {
934 l2tp_info(tunnel, L2TP_MSG_DATA,
935 "%s: recv protocol version mismatch: got %d expected %d\n",
936 tunnel->name, version, tunnel->version);
937 goto error;
938 }
939
940 /* Get length of L2TP packet */
941 length = skb->len;
942
943 /* If type is control packet, it is handled by userspace. */
944 if (hdrflags & L2TP_HDRFLAG_T) {
945 l2tp_dbg(tunnel, L2TP_MSG_DATA,
946 "%s: recv control packet, len=%d\n",
947 tunnel->name, length);
948 goto error;
949 }
950
951 /* Skip flags */
952 ptr += 2;
953
954 if (tunnel->version == L2TP_HDR_VER_2) {
955 /* If length is present, skip it */
956 if (hdrflags & L2TP_HDRFLAG_L)
957 ptr += 2;
958
959 /* Extract tunnel and session ID */
960 tunnel_id = ntohs(*(__be16 *) ptr);
961 ptr += 2;
962 session_id = ntohs(*(__be16 *) ptr);
963 ptr += 2;
964 } else {
965 ptr += 2; /* skip reserved bits */
966 tunnel_id = tunnel->tunnel_id;
967 session_id = ntohl(*(__be32 *) ptr);
968 ptr += 4;
969 }
970
971 /* Find the session context */
972 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
973 if (!session || !session->recv_skb) {
974 /* Not found? Pass to userspace to deal with */
975 l2tp_info(tunnel, L2TP_MSG_DATA,
976 "%s: no session found (%u/%u). Passing up.\n",
977 tunnel->name, tunnel_id, session_id);
978 goto error;
979 }
980
981 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
982
983 return 0;
984
985 discard_bad_csum:
986 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
987 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
988 atomic_long_inc(&tunnel->stats.rx_errors);
989 kfree_skb(skb);
990
991 return 0;
992
993 error:
994 /* Put UDP header back */
995 __skb_push(skb, sizeof(struct udphdr));
996
997 return 1;
998 }
999
1000 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
1001 * Return codes:
1002 * 0 : success.
1003 * <0: error
1004 * >0: skb should be passed up to userspace as UDP.
1005 */
1006 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1007 {
1008 struct l2tp_tunnel *tunnel;
1009
1010 tunnel = l2tp_sock_to_tunnel(sk);
1011 if (tunnel == NULL)
1012 goto pass_up;
1013
1014 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1015 tunnel->name, skb->len);
1016
1017 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1018 goto pass_up_put;
1019
1020 sock_put(sk);
1021 return 0;
1022
1023 pass_up_put:
1024 sock_put(sk);
1025 pass_up:
1026 return 1;
1027 }
1028 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1029
1030 /************************************************************************
1031 * Transmit handling
1032 ***********************************************************************/
1033
1034 /* Build an L2TP header for the session into the buffer provided.
1035 */
1036 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1037 {
1038 struct l2tp_tunnel *tunnel = session->tunnel;
1039 __be16 *bufp = buf;
1040 __be16 *optr = buf;
1041 u16 flags = L2TP_HDR_VER_2;
1042 u32 tunnel_id = tunnel->peer_tunnel_id;
1043 u32 session_id = session->peer_session_id;
1044
1045 if (session->send_seq)
1046 flags |= L2TP_HDRFLAG_S;
1047
1048 /* Setup L2TP header. */
1049 *bufp++ = htons(flags);
1050 *bufp++ = htons(tunnel_id);
1051 *bufp++ = htons(session_id);
1052 if (session->send_seq) {
1053 *bufp++ = htons(session->ns);
1054 *bufp++ = 0;
1055 session->ns++;
1056 session->ns &= 0xffff;
1057 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1058 session->name, session->ns);
1059 }
1060
1061 return bufp - optr;
1062 }
1063
1064 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1065 {
1066 struct l2tp_tunnel *tunnel = session->tunnel;
1067 char *bufp = buf;
1068 char *optr = bufp;
1069
1070 /* Setup L2TP header. The header differs slightly for UDP and
1071 * IP encapsulations. For UDP, there is 4 bytes of flags.
1072 */
1073 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1074 u16 flags = L2TP_HDR_VER_3;
1075 *((__be16 *) bufp) = htons(flags);
1076 bufp += 2;
1077 *((__be16 *) bufp) = 0;
1078 bufp += 2;
1079 }
1080
1081 *((__be32 *) bufp) = htonl(session->peer_session_id);
1082 bufp += 4;
1083 if (session->cookie_len) {
1084 memcpy(bufp, &session->cookie[0], session->cookie_len);
1085 bufp += session->cookie_len;
1086 }
1087 if (session->l2specific_len) {
1088 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1089 u32 l2h = 0;
1090 if (session->send_seq) {
1091 l2h = 0x40000000 | session->ns;
1092 session->ns++;
1093 session->ns &= 0xffffff;
1094 l2tp_dbg(session, L2TP_MSG_SEQ,
1095 "%s: updated ns to %u\n",
1096 session->name, session->ns);
1097 }
1098
1099 *((__be32 *) bufp) = htonl(l2h);
1100 }
1101 bufp += session->l2specific_len;
1102 }
1103 if (session->offset)
1104 bufp += session->offset;
1105
1106 return bufp - optr;
1107 }
1108
1109 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1110 struct flowi *fl, size_t data_len)
1111 {
1112 struct l2tp_tunnel *tunnel = session->tunnel;
1113 unsigned int len = skb->len;
1114 int error;
1115
1116 /* Debug */
1117 if (session->send_seq)
1118 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1119 session->name, data_len, session->ns - 1);
1120 else
1121 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1122 session->name, data_len);
1123
1124 if (session->debug & L2TP_MSG_DATA) {
1125 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1126 unsigned char *datap = skb->data + uhlen;
1127
1128 pr_debug("%s: xmit\n", session->name);
1129 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1130 datap, min_t(size_t, 32, len - uhlen));
1131 }
1132
1133 /* Queue the packet to IP for output */
1134 skb->local_df = 1;
1135 #if IS_ENABLED(CONFIG_IPV6)
1136 if (skb->sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1137 error = inet6_csk_xmit(skb, NULL);
1138 else
1139 #endif
1140 error = ip_queue_xmit(skb, fl);
1141
1142 /* Update stats */
1143 if (error >= 0) {
1144 atomic_long_inc(&tunnel->stats.tx_packets);
1145 atomic_long_add(len, &tunnel->stats.tx_bytes);
1146 atomic_long_inc(&session->stats.tx_packets);
1147 atomic_long_add(len, &session->stats.tx_bytes);
1148 } else {
1149 atomic_long_inc(&tunnel->stats.tx_errors);
1150 atomic_long_inc(&session->stats.tx_errors);
1151 }
1152
1153 return 0;
1154 }
1155
1156 /* Automatically called when the skb is freed.
1157 */
1158 static void l2tp_sock_wfree(struct sk_buff *skb)
1159 {
1160 sock_put(skb->sk);
1161 }
1162
1163 /* For data skbs that we transmit, we associate with the tunnel socket
1164 * but don't do accounting.
1165 */
1166 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1167 {
1168 sock_hold(sk);
1169 skb->sk = sk;
1170 skb->destructor = l2tp_sock_wfree;
1171 }
1172
1173 #if IS_ENABLED(CONFIG_IPV6)
1174 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1175 int udp_len)
1176 {
1177 struct ipv6_pinfo *np = inet6_sk(sk);
1178 struct udphdr *uh = udp_hdr(skb);
1179
1180 if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1181 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1182 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1183 skb->ip_summed = CHECKSUM_UNNECESSARY;
1184 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1185 IPPROTO_UDP, csum);
1186 if (uh->check == 0)
1187 uh->check = CSUM_MANGLED_0;
1188 } else {
1189 skb->ip_summed = CHECKSUM_PARTIAL;
1190 skb->csum_start = skb_transport_header(skb) - skb->head;
1191 skb->csum_offset = offsetof(struct udphdr, check);
1192 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1193 udp_len, IPPROTO_UDP, 0);
1194 }
1195 }
1196 #endif
1197
1198 /* If caller requires the skb to have a ppp header, the header must be
1199 * inserted in the skb data before calling this function.
1200 */
1201 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1202 {
1203 int data_len = skb->len;
1204 struct l2tp_tunnel *tunnel = session->tunnel;
1205 struct sock *sk = tunnel->sock;
1206 struct flowi *fl;
1207 struct udphdr *uh;
1208 struct inet_sock *inet;
1209 __wsum csum;
1210 int headroom;
1211 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1212 int udp_len;
1213 int ret = NET_XMIT_SUCCESS;
1214
1215 /* Check that there's enough headroom in the skb to insert IP,
1216 * UDP and L2TP headers. If not enough, expand it to
1217 * make room. Adjust truesize.
1218 */
1219 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1220 uhlen + hdr_len;
1221 if (skb_cow_head(skb, headroom)) {
1222 kfree_skb(skb);
1223 return NET_XMIT_DROP;
1224 }
1225
1226 skb_orphan(skb);
1227 /* Setup L2TP header */
1228 session->build_header(session, __skb_push(skb, hdr_len));
1229
1230 /* Reset skb netfilter state */
1231 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1232 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1233 IPSKB_REROUTED);
1234 nf_reset(skb);
1235
1236 bh_lock_sock(sk);
1237 if (sock_owned_by_user(sk)) {
1238 kfree_skb(skb);
1239 ret = NET_XMIT_DROP;
1240 goto out_unlock;
1241 }
1242
1243 /* Get routing info from the tunnel socket */
1244 skb_dst_drop(skb);
1245 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1246
1247 inet = inet_sk(sk);
1248 fl = &inet->cork.fl;
1249 switch (tunnel->encap) {
1250 case L2TP_ENCAPTYPE_UDP:
1251 /* Setup UDP header */
1252 __skb_push(skb, sizeof(*uh));
1253 skb_reset_transport_header(skb);
1254 uh = udp_hdr(skb);
1255 uh->source = inet->inet_sport;
1256 uh->dest = inet->inet_dport;
1257 udp_len = uhlen + hdr_len + data_len;
1258 uh->len = htons(udp_len);
1259 uh->check = 0;
1260
1261 /* Calculate UDP checksum if configured to do so */
1262 #if IS_ENABLED(CONFIG_IPV6)
1263 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1264 l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1265 else
1266 #endif
1267 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1268 skb->ip_summed = CHECKSUM_NONE;
1269 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1270 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1271 skb->ip_summed = CHECKSUM_COMPLETE;
1272 csum = skb_checksum(skb, 0, udp_len, 0);
1273 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1274 inet->inet_daddr,
1275 udp_len, IPPROTO_UDP, csum);
1276 if (uh->check == 0)
1277 uh->check = CSUM_MANGLED_0;
1278 } else {
1279 skb->ip_summed = CHECKSUM_PARTIAL;
1280 skb->csum_start = skb_transport_header(skb) - skb->head;
1281 skb->csum_offset = offsetof(struct udphdr, check);
1282 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1283 inet->inet_daddr,
1284 udp_len, IPPROTO_UDP, 0);
1285 }
1286 break;
1287
1288 case L2TP_ENCAPTYPE_IP:
1289 break;
1290 }
1291
1292 l2tp_skb_set_owner_w(skb, sk);
1293
1294 l2tp_xmit_core(session, skb, fl, data_len);
1295 out_unlock:
1296 bh_unlock_sock(sk);
1297
1298 return ret;
1299 }
1300 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1301
1302 /*****************************************************************************
1303 * Tinnel and session create/destroy.
1304 *****************************************************************************/
1305
1306 /* Tunnel socket destruct hook.
1307 * The tunnel context is deleted only when all session sockets have been
1308 * closed.
1309 */
1310 static void l2tp_tunnel_destruct(struct sock *sk)
1311 {
1312 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1313 struct l2tp_net *pn;
1314
1315 if (tunnel == NULL)
1316 goto end;
1317
1318 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1319
1320
1321 /* Disable udp encapsulation */
1322 switch (tunnel->encap) {
1323 case L2TP_ENCAPTYPE_UDP:
1324 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1325 (udp_sk(sk))->encap_type = 0;
1326 (udp_sk(sk))->encap_rcv = NULL;
1327 (udp_sk(sk))->encap_destroy = NULL;
1328 break;
1329 case L2TP_ENCAPTYPE_IP:
1330 break;
1331 }
1332
1333 /* Remove hooks into tunnel socket */
1334 sk->sk_destruct = tunnel->old_sk_destruct;
1335 sk->sk_user_data = NULL;
1336 tunnel->sock = NULL;
1337
1338 /* Remove the tunnel struct from the tunnel list */
1339 pn = l2tp_pernet(tunnel->l2tp_net);
1340 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1341 list_del_rcu(&tunnel->list);
1342 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1343 atomic_dec(&l2tp_tunnel_count);
1344
1345 l2tp_tunnel_closeall(tunnel);
1346 l2tp_tunnel_dec_refcount(tunnel);
1347
1348 /* Call the original destructor */
1349 if (sk->sk_destruct)
1350 (*sk->sk_destruct)(sk);
1351 end:
1352 return;
1353 }
1354
1355 /* When the tunnel is closed, all the attached sessions need to go too.
1356 */
1357 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1358 {
1359 int hash;
1360 struct hlist_node *walk;
1361 struct hlist_node *tmp;
1362 struct l2tp_session *session;
1363
1364 BUG_ON(tunnel == NULL);
1365
1366 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1367 tunnel->name);
1368
1369 write_lock_bh(&tunnel->hlist_lock);
1370 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1371 again:
1372 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1373 session = hlist_entry(walk, struct l2tp_session, hlist);
1374
1375 l2tp_info(session, L2TP_MSG_CONTROL,
1376 "%s: closing session\n", session->name);
1377
1378 hlist_del_init(&session->hlist);
1379
1380 if (session->ref != NULL)
1381 (*session->ref)(session);
1382
1383 write_unlock_bh(&tunnel->hlist_lock);
1384
1385 __l2tp_session_unhash(session);
1386 l2tp_session_queue_purge(session);
1387
1388 if (session->session_close != NULL)
1389 (*session->session_close)(session);
1390
1391 if (session->deref != NULL)
1392 (*session->deref)(session);
1393
1394 l2tp_session_dec_refcount(session);
1395
1396 write_lock_bh(&tunnel->hlist_lock);
1397
1398 /* Now restart from the beginning of this hash
1399 * chain. We always remove a session from the
1400 * list so we are guaranteed to make forward
1401 * progress.
1402 */
1403 goto again;
1404 }
1405 }
1406 write_unlock_bh(&tunnel->hlist_lock);
1407 }
1408 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1409
1410 /* Tunnel socket destroy hook for UDP encapsulation */
1411 static void l2tp_udp_encap_destroy(struct sock *sk)
1412 {
1413 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1414 if (tunnel) {
1415 l2tp_tunnel_closeall(tunnel);
1416 sock_put(sk);
1417 }
1418 }
1419
1420 /* Really kill the tunnel.
1421 * Come here only when all sessions have been cleared from the tunnel.
1422 */
1423 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1424 {
1425 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1426 BUG_ON(tunnel->sock != NULL);
1427 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1428 kfree_rcu(tunnel, rcu);
1429 }
1430
1431 /* Workqueue tunnel deletion function */
1432 static void l2tp_tunnel_del_work(struct work_struct *work)
1433 {
1434 struct l2tp_tunnel *tunnel = NULL;
1435 struct socket *sock = NULL;
1436 struct sock *sk = NULL;
1437
1438 tunnel = container_of(work, struct l2tp_tunnel, del_work);
1439 sk = l2tp_tunnel_sock_lookup(tunnel);
1440 if (!sk)
1441 return;
1442
1443 sock = sk->sk_socket;
1444
1445 /* If the tunnel socket was created by userspace, then go through the
1446 * inet layer to shut the socket down, and let userspace close it.
1447 * Otherwise, if we created the socket directly within the kernel, use
1448 * the sk API to release it here.
1449 * In either case the tunnel resources are freed in the socket
1450 * destructor when the tunnel socket goes away.
1451 */
1452 if (tunnel->fd >= 0) {
1453 if (sock)
1454 inet_shutdown(sock, 2);
1455 } else {
1456 if (sock)
1457 kernel_sock_shutdown(sock, SHUT_RDWR);
1458 sk_release_kernel(sk);
1459 }
1460
1461 l2tp_tunnel_sock_put(sk);
1462 }
1463
1464 /* Create a socket for the tunnel, if one isn't set up by
1465 * userspace. This is used for static tunnels where there is no
1466 * managing L2TP daemon.
1467 *
1468 * Since we don't want these sockets to keep a namespace alive by
1469 * themselves, we drop the socket's namespace refcount after creation.
1470 * These sockets are freed when the namespace exits using the pernet
1471 * exit hook.
1472 */
1473 static int l2tp_tunnel_sock_create(struct net *net,
1474 u32 tunnel_id,
1475 u32 peer_tunnel_id,
1476 struct l2tp_tunnel_cfg *cfg,
1477 struct socket **sockp)
1478 {
1479 int err = -EINVAL;
1480 struct socket *sock = NULL;
1481 struct sockaddr_in udp_addr = {0};
1482 struct sockaddr_l2tpip ip_addr = {0};
1483 #if IS_ENABLED(CONFIG_IPV6)
1484 struct sockaddr_in6 udp6_addr = {0};
1485 struct sockaddr_l2tpip6 ip6_addr = {0};
1486 #endif
1487
1488 switch (cfg->encap) {
1489 case L2TP_ENCAPTYPE_UDP:
1490 #if IS_ENABLED(CONFIG_IPV6)
1491 if (cfg->local_ip6 && cfg->peer_ip6) {
1492 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1493 if (err < 0)
1494 goto out;
1495
1496 sk_change_net(sock->sk, net);
1497
1498 udp6_addr.sin6_family = AF_INET6;
1499 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1500 sizeof(udp6_addr.sin6_addr));
1501 udp6_addr.sin6_port = htons(cfg->local_udp_port);
1502 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1503 sizeof(udp6_addr));
1504 if (err < 0)
1505 goto out;
1506
1507 udp6_addr.sin6_family = AF_INET6;
1508 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1509 sizeof(udp6_addr.sin6_addr));
1510 udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1511 err = kernel_connect(sock,
1512 (struct sockaddr *) &udp6_addr,
1513 sizeof(udp6_addr), 0);
1514 if (err < 0)
1515 goto out;
1516 } else
1517 #endif
1518 {
1519 err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1520 if (err < 0)
1521 goto out;
1522
1523 sk_change_net(sock->sk, net);
1524
1525 udp_addr.sin_family = AF_INET;
1526 udp_addr.sin_addr = cfg->local_ip;
1527 udp_addr.sin_port = htons(cfg->local_udp_port);
1528 err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1529 sizeof(udp_addr));
1530 if (err < 0)
1531 goto out;
1532
1533 udp_addr.sin_family = AF_INET;
1534 udp_addr.sin_addr = cfg->peer_ip;
1535 udp_addr.sin_port = htons(cfg->peer_udp_port);
1536 err = kernel_connect(sock,
1537 (struct sockaddr *) &udp_addr,
1538 sizeof(udp_addr), 0);
1539 if (err < 0)
1540 goto out;
1541 }
1542
1543 if (!cfg->use_udp_checksums)
1544 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1545
1546 break;
1547
1548 case L2TP_ENCAPTYPE_IP:
1549 #if IS_ENABLED(CONFIG_IPV6)
1550 if (cfg->local_ip6 && cfg->peer_ip6) {
1551 err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1552 IPPROTO_L2TP, &sock);
1553 if (err < 0)
1554 goto out;
1555
1556 sk_change_net(sock->sk, net);
1557
1558 ip6_addr.l2tp_family = AF_INET6;
1559 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1560 sizeof(ip6_addr.l2tp_addr));
1561 ip6_addr.l2tp_conn_id = tunnel_id;
1562 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1563 sizeof(ip6_addr));
1564 if (err < 0)
1565 goto out;
1566
1567 ip6_addr.l2tp_family = AF_INET6;
1568 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1569 sizeof(ip6_addr.l2tp_addr));
1570 ip6_addr.l2tp_conn_id = peer_tunnel_id;
1571 err = kernel_connect(sock,
1572 (struct sockaddr *) &ip6_addr,
1573 sizeof(ip6_addr), 0);
1574 if (err < 0)
1575 goto out;
1576 } else
1577 #endif
1578 {
1579 err = sock_create_kern(AF_INET, SOCK_DGRAM,
1580 IPPROTO_L2TP, &sock);
1581 if (err < 0)
1582 goto out;
1583
1584 sk_change_net(sock->sk, net);
1585
1586 ip_addr.l2tp_family = AF_INET;
1587 ip_addr.l2tp_addr = cfg->local_ip;
1588 ip_addr.l2tp_conn_id = tunnel_id;
1589 err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1590 sizeof(ip_addr));
1591 if (err < 0)
1592 goto out;
1593
1594 ip_addr.l2tp_family = AF_INET;
1595 ip_addr.l2tp_addr = cfg->peer_ip;
1596 ip_addr.l2tp_conn_id = peer_tunnel_id;
1597 err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1598 sizeof(ip_addr), 0);
1599 if (err < 0)
1600 goto out;
1601 }
1602 break;
1603
1604 default:
1605 goto out;
1606 }
1607
1608 out:
1609 *sockp = sock;
1610 if ((err < 0) && sock) {
1611 kernel_sock_shutdown(sock, SHUT_RDWR);
1612 sk_release_kernel(sock->sk);
1613 *sockp = NULL;
1614 }
1615
1616 return err;
1617 }
1618
1619 static struct lock_class_key l2tp_socket_class;
1620
1621 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
1622 {
1623 struct l2tp_tunnel *tunnel = NULL;
1624 int err;
1625 struct socket *sock = NULL;
1626 struct sock *sk = NULL;
1627 struct l2tp_net *pn;
1628 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1629
1630 /* Get the tunnel socket from the fd, which was opened by
1631 * the userspace L2TP daemon. If not specified, create a
1632 * kernel socket.
1633 */
1634 if (fd < 0) {
1635 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1636 cfg, &sock);
1637 if (err < 0)
1638 goto err;
1639 } else {
1640 sock = sockfd_lookup(fd, &err);
1641 if (!sock) {
1642 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1643 tunnel_id, fd, err);
1644 err = -EBADF;
1645 goto err;
1646 }
1647
1648 /* Reject namespace mismatches */
1649 if (!net_eq(sock_net(sock->sk), net)) {
1650 pr_err("tunl %u: netns mismatch\n", tunnel_id);
1651 err = -EINVAL;
1652 goto err;
1653 }
1654 }
1655
1656 sk = sock->sk;
1657
1658 if (cfg != NULL)
1659 encap = cfg->encap;
1660
1661 /* Quick sanity checks */
1662 switch (encap) {
1663 case L2TP_ENCAPTYPE_UDP:
1664 err = -EPROTONOSUPPORT;
1665 if (sk->sk_protocol != IPPROTO_UDP) {
1666 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1667 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1668 goto err;
1669 }
1670 break;
1671 case L2TP_ENCAPTYPE_IP:
1672 err = -EPROTONOSUPPORT;
1673 if (sk->sk_protocol != IPPROTO_L2TP) {
1674 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1675 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1676 goto err;
1677 }
1678 break;
1679 }
1680
1681 /* Check if this socket has already been prepped */
1682 tunnel = l2tp_tunnel(sk);
1683 if (tunnel != NULL) {
1684 /* This socket has already been prepped */
1685 err = -EBUSY;
1686 goto err;
1687 }
1688
1689 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1690 if (tunnel == NULL) {
1691 err = -ENOMEM;
1692 goto err;
1693 }
1694
1695 tunnel->version = version;
1696 tunnel->tunnel_id = tunnel_id;
1697 tunnel->peer_tunnel_id = peer_tunnel_id;
1698 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1699
1700 tunnel->magic = L2TP_TUNNEL_MAGIC;
1701 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1702 rwlock_init(&tunnel->hlist_lock);
1703
1704 /* The net we belong to */
1705 tunnel->l2tp_net = net;
1706 pn = l2tp_pernet(net);
1707
1708 if (cfg != NULL)
1709 tunnel->debug = cfg->debug;
1710
1711 #if IS_ENABLED(CONFIG_IPV6)
1712 if (sk->sk_family == PF_INET6) {
1713 struct ipv6_pinfo *np = inet6_sk(sk);
1714
1715 if (ipv6_addr_v4mapped(&np->saddr) &&
1716 ipv6_addr_v4mapped(&np->daddr)) {
1717 struct inet_sock *inet = inet_sk(sk);
1718
1719 tunnel->v4mapped = true;
1720 inet->inet_saddr = np->saddr.s6_addr32[3];
1721 inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3];
1722 inet->inet_daddr = np->daddr.s6_addr32[3];
1723 } else {
1724 tunnel->v4mapped = false;
1725 }
1726 }
1727 #endif
1728
1729 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1730 tunnel->encap = encap;
1731 if (encap == L2TP_ENCAPTYPE_UDP) {
1732 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1733 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1734 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1735 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
1736 #if IS_ENABLED(CONFIG_IPV6)
1737 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1738 udpv6_encap_enable();
1739 else
1740 #endif
1741 udp_encap_enable();
1742 }
1743
1744 sk->sk_user_data = tunnel;
1745
1746 /* Hook on the tunnel socket destructor so that we can cleanup
1747 * if the tunnel socket goes away.
1748 */
1749 tunnel->old_sk_destruct = sk->sk_destruct;
1750 sk->sk_destruct = &l2tp_tunnel_destruct;
1751 tunnel->sock = sk;
1752 tunnel->fd = fd;
1753 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1754
1755 sk->sk_allocation = GFP_ATOMIC;
1756
1757 /* Init delete workqueue struct */
1758 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1759
1760 /* Add tunnel to our list */
1761 INIT_LIST_HEAD(&tunnel->list);
1762 atomic_inc(&l2tp_tunnel_count);
1763
1764 /* Bump the reference count. The tunnel context is deleted
1765 * only when this drops to zero. Must be done before list insertion
1766 */
1767 l2tp_tunnel_inc_refcount(tunnel);
1768 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1769 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1770 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1771
1772 err = 0;
1773 err:
1774 if (tunnelp)
1775 *tunnelp = tunnel;
1776
1777 /* If tunnel's socket was created by the kernel, it doesn't
1778 * have a file.
1779 */
1780 if (sock && sock->file)
1781 sockfd_put(sock);
1782
1783 return err;
1784 }
1785 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1786
1787 /* This function is used by the netlink TUNNEL_DELETE command.
1788 */
1789 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1790 {
1791 l2tp_tunnel_closeall(tunnel);
1792 return (false == queue_work(l2tp_wq, &tunnel->del_work));
1793 }
1794 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1795
1796 /* Really kill the session.
1797 */
1798 void l2tp_session_free(struct l2tp_session *session)
1799 {
1800 struct l2tp_tunnel *tunnel = session->tunnel;
1801
1802 BUG_ON(atomic_read(&session->ref_count) != 0);
1803
1804 if (tunnel) {
1805 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1806 if (session->session_id != 0)
1807 atomic_dec(&l2tp_session_count);
1808 sock_put(tunnel->sock);
1809 session->tunnel = NULL;
1810 l2tp_tunnel_dec_refcount(tunnel);
1811 }
1812
1813 kfree(session);
1814
1815 return;
1816 }
1817 EXPORT_SYMBOL_GPL(l2tp_session_free);
1818
1819 /* Remove an l2tp session from l2tp_core's hash lists.
1820 * Provides a tidyup interface for pseudowire code which can't just route all
1821 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1822 * callback.
1823 */
1824 void __l2tp_session_unhash(struct l2tp_session *session)
1825 {
1826 struct l2tp_tunnel *tunnel = session->tunnel;
1827
1828 /* Remove the session from core hashes */
1829 if (tunnel) {
1830 /* Remove from the per-tunnel hash */
1831 write_lock_bh(&tunnel->hlist_lock);
1832 hlist_del_init(&session->hlist);
1833 write_unlock_bh(&tunnel->hlist_lock);
1834
1835 /* For L2TPv3 we have a per-net hash: remove from there, too */
1836 if (tunnel->version != L2TP_HDR_VER_2) {
1837 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1838 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1839 hlist_del_init_rcu(&session->global_hlist);
1840 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1841 synchronize_rcu();
1842 }
1843 }
1844 }
1845 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1846
1847 /* This function is used by the netlink SESSION_DELETE command and by
1848 pseudowire modules.
1849 */
1850 int l2tp_session_delete(struct l2tp_session *session)
1851 {
1852 if (session->ref)
1853 (*session->ref)(session);
1854 __l2tp_session_unhash(session);
1855 l2tp_session_queue_purge(session);
1856 if (session->session_close != NULL)
1857 (*session->session_close)(session);
1858 if (session->deref)
1859 (*session->deref)(session);
1860 l2tp_session_dec_refcount(session);
1861 return 0;
1862 }
1863 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1864
1865 /* We come here whenever a session's send_seq, cookie_len or
1866 * l2specific_len parameters are set.
1867 */
1868 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1869 {
1870 if (version == L2TP_HDR_VER_2) {
1871 session->hdr_len = 6;
1872 if (session->send_seq)
1873 session->hdr_len += 4;
1874 } else {
1875 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1876 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1877 session->hdr_len += 4;
1878 }
1879
1880 }
1881
1882 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
1883 {
1884 struct l2tp_session *session;
1885
1886 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1887 if (session != NULL) {
1888 session->magic = L2TP_SESSION_MAGIC;
1889 session->tunnel = tunnel;
1890
1891 session->session_id = session_id;
1892 session->peer_session_id = peer_session_id;
1893 session->nr = 0;
1894 if (tunnel->version == L2TP_HDR_VER_2)
1895 session->nr_max = 0xffff;
1896 else
1897 session->nr_max = 0xffffff;
1898 session->nr_window_size = session->nr_max / 2;
1899 session->nr_oos_count_max = 4;
1900
1901 /* Use NR of first received packet */
1902 session->reorder_skip = 1;
1903
1904 sprintf(&session->name[0], "sess %u/%u",
1905 tunnel->tunnel_id, session->session_id);
1906
1907 skb_queue_head_init(&session->reorder_q);
1908
1909 INIT_HLIST_NODE(&session->hlist);
1910 INIT_HLIST_NODE(&session->global_hlist);
1911
1912 /* Inherit debug options from tunnel */
1913 session->debug = tunnel->debug;
1914
1915 if (cfg) {
1916 session->pwtype = cfg->pw_type;
1917 session->debug = cfg->debug;
1918 session->mtu = cfg->mtu;
1919 session->mru = cfg->mru;
1920 session->send_seq = cfg->send_seq;
1921 session->recv_seq = cfg->recv_seq;
1922 session->lns_mode = cfg->lns_mode;
1923 session->reorder_timeout = cfg->reorder_timeout;
1924 session->offset = cfg->offset;
1925 session->l2specific_type = cfg->l2specific_type;
1926 session->l2specific_len = cfg->l2specific_len;
1927 session->cookie_len = cfg->cookie_len;
1928 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1929 session->peer_cookie_len = cfg->peer_cookie_len;
1930 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1931 }
1932
1933 if (tunnel->version == L2TP_HDR_VER_2)
1934 session->build_header = l2tp_build_l2tpv2_header;
1935 else
1936 session->build_header = l2tp_build_l2tpv3_header;
1937
1938 l2tp_session_set_header_len(session, tunnel->version);
1939
1940 /* Bump the reference count. The session context is deleted
1941 * only when this drops to zero.
1942 */
1943 l2tp_session_inc_refcount(session);
1944 l2tp_tunnel_inc_refcount(tunnel);
1945
1946 /* Ensure tunnel socket isn't deleted */
1947 sock_hold(tunnel->sock);
1948
1949 /* Add session to the tunnel's hash list */
1950 write_lock_bh(&tunnel->hlist_lock);
1951 hlist_add_head(&session->hlist,
1952 l2tp_session_id_hash(tunnel, session_id));
1953 write_unlock_bh(&tunnel->hlist_lock);
1954
1955 /* And to the global session list if L2TPv3 */
1956 if (tunnel->version != L2TP_HDR_VER_2) {
1957 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1958
1959 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1960 hlist_add_head_rcu(&session->global_hlist,
1961 l2tp_session_id_hash_2(pn, session_id));
1962 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1963 }
1964
1965 /* Ignore management session in session count value */
1966 if (session->session_id != 0)
1967 atomic_inc(&l2tp_session_count);
1968 }
1969
1970 return session;
1971 }
1972 EXPORT_SYMBOL_GPL(l2tp_session_create);
1973
1974 /*****************************************************************************
1975 * Init and cleanup
1976 *****************************************************************************/
1977
1978 static __net_init int l2tp_init_net(struct net *net)
1979 {
1980 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1981 int hash;
1982
1983 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1984 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1985
1986 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1987 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1988
1989 spin_lock_init(&pn->l2tp_session_hlist_lock);
1990
1991 return 0;
1992 }
1993
1994 static __net_exit void l2tp_exit_net(struct net *net)
1995 {
1996 struct l2tp_net *pn = l2tp_pernet(net);
1997 struct l2tp_tunnel *tunnel = NULL;
1998
1999 rcu_read_lock_bh();
2000 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
2001 (void)l2tp_tunnel_delete(tunnel);
2002 }
2003 rcu_read_unlock_bh();
2004 }
2005
2006 static struct pernet_operations l2tp_net_ops = {
2007 .init = l2tp_init_net,
2008 .exit = l2tp_exit_net,
2009 .id = &l2tp_net_id,
2010 .size = sizeof(struct l2tp_net),
2011 };
2012
2013 static int __init l2tp_init(void)
2014 {
2015 int rc = 0;
2016
2017 rc = register_pernet_device(&l2tp_net_ops);
2018 if (rc)
2019 goto out;
2020
2021 l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
2022 if (!l2tp_wq) {
2023 pr_err("alloc_workqueue failed\n");
2024 rc = -ENOMEM;
2025 goto out;
2026 }
2027
2028 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
2029
2030 out:
2031 return rc;
2032 }
2033
2034 static void __exit l2tp_exit(void)
2035 {
2036 unregister_pernet_device(&l2tp_net_ops);
2037 if (l2tp_wq) {
2038 destroy_workqueue(l2tp_wq);
2039 l2tp_wq = NULL;
2040 }
2041 }
2042
2043 module_init(l2tp_init);
2044 module_exit(l2tp_exit);
2045
2046 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
2047 MODULE_DESCRIPTION("L2TP core");
2048 MODULE_LICENSE("GPL");
2049 MODULE_VERSION(L2TP_DRV_VERSION);
2050
Linux with added FPC-III support