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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...
[linux/fpc-iii.git] / net / l2tp / l2tp_core.c
blob735d0f60c83a126683b599d1e967eb9ca18b0471
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 static 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
206 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
207 static void l2tp_tunnel_sock_put(struct sock *sk)
208 {
209 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
210 if (tunnel) {
211 if (tunnel->fd >= 0) {
212 /* Socket is owned by userspace */
213 sockfd_put(sk->sk_socket);
214 }
215 sock_put(sk);
216 }
217 sock_put(sk);
218 }
219
220 /* Lookup a session by id in the global session list
221 */
222 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
223 {
224 struct l2tp_net *pn = l2tp_pernet(net);
225 struct hlist_head *session_list =
226 l2tp_session_id_hash_2(pn, session_id);
227 struct l2tp_session *session;
228
229 rcu_read_lock_bh();
230 hlist_for_each_entry_rcu(session, session_list, global_hlist) {
231 if (session->session_id == session_id) {
232 rcu_read_unlock_bh();
233 return session;
234 }
235 }
236 rcu_read_unlock_bh();
237
238 return NULL;
239 }
240
241 /* Session hash list.
242 * The session_id SHOULD be random according to RFC2661, but several
243 * L2TP implementations (Cisco and Microsoft) use incrementing
244 * session_ids. So we do a real hash on the session_id, rather than a
245 * simple bitmask.
246 */
247 static inline struct hlist_head *
248 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
249 {
250 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
251 }
252
253 /* Lookup a session by id
254 */
255 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
256 {
257 struct hlist_head *session_list;
258 struct l2tp_session *session;
259
260 /* In L2TPv3, session_ids are unique over all tunnels and we
261 * sometimes need to look them up before we know the
262 * tunnel.
263 */
264 if (tunnel == NULL)
265 return l2tp_session_find_2(net, session_id);
266
267 session_list = l2tp_session_id_hash(tunnel, session_id);
268 read_lock_bh(&tunnel->hlist_lock);
269 hlist_for_each_entry(session, session_list, hlist) {
270 if (session->session_id == session_id) {
271 read_unlock_bh(&tunnel->hlist_lock);
272 return session;
273 }
274 }
275 read_unlock_bh(&tunnel->hlist_lock);
276
277 return NULL;
278 }
279 EXPORT_SYMBOL_GPL(l2tp_session_find);
280
281 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
282 {
283 int hash;
284 struct l2tp_session *session;
285 int count = 0;
286
287 read_lock_bh(&tunnel->hlist_lock);
288 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
289 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
290 if (++count > nth) {
291 read_unlock_bh(&tunnel->hlist_lock);
292 return session;
293 }
294 }
295 }
296
297 read_unlock_bh(&tunnel->hlist_lock);
298
299 return NULL;
300 }
301 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
302
303 /* Lookup a session by interface name.
304 * This is very inefficient but is only used by management interfaces.
305 */
306 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
307 {
308 struct l2tp_net *pn = l2tp_pernet(net);
309 int hash;
310 struct l2tp_session *session;
311
312 rcu_read_lock_bh();
313 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
314 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
315 if (!strcmp(session->ifname, ifname)) {
316 rcu_read_unlock_bh();
317 return session;
318 }
319 }
320 }
321
322 rcu_read_unlock_bh();
323
324 return NULL;
325 }
326 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
327
328 /* Lookup a tunnel by id
329 */
330 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
331 {
332 struct l2tp_tunnel *tunnel;
333 struct l2tp_net *pn = l2tp_pernet(net);
334
335 rcu_read_lock_bh();
336 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
337 if (tunnel->tunnel_id == tunnel_id) {
338 rcu_read_unlock_bh();
339 return tunnel;
340 }
341 }
342 rcu_read_unlock_bh();
343
344 return NULL;
345 }
346 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
347
348 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
349 {
350 struct l2tp_net *pn = l2tp_pernet(net);
351 struct l2tp_tunnel *tunnel;
352 int count = 0;
353
354 rcu_read_lock_bh();
355 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
356 if (++count > nth) {
357 rcu_read_unlock_bh();
358 return tunnel;
359 }
360 }
361
362 rcu_read_unlock_bh();
363
364 return NULL;
365 }
366 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
367
368 /*****************************************************************************
369 * Receive data handling
370 *****************************************************************************/
371
372 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
373 * number.
374 */
375 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
376 {
377 struct sk_buff *skbp;
378 struct sk_buff *tmp;
379 u32 ns = L2TP_SKB_CB(skb)->ns;
380
381 spin_lock_bh(&session->reorder_q.lock);
382 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
383 if (L2TP_SKB_CB(skbp)->ns > ns) {
384 __skb_queue_before(&session->reorder_q, skbp, skb);
385 l2tp_dbg(session, L2TP_MSG_SEQ,
386 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
387 session->name, ns, L2TP_SKB_CB(skbp)->ns,
388 skb_queue_len(&session->reorder_q));
389 atomic_long_inc(&session->stats.rx_oos_packets);
390 goto out;
391 }
392 }
393
394 __skb_queue_tail(&session->reorder_q, skb);
395
396 out:
397 spin_unlock_bh(&session->reorder_q.lock);
398 }
399
400 /* Dequeue a single skb.
401 */
402 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
403 {
404 struct l2tp_tunnel *tunnel = session->tunnel;
405 int length = L2TP_SKB_CB(skb)->length;
406
407 /* We're about to requeue the skb, so return resources
408 * to its current owner (a socket receive buffer).
409 */
410 skb_orphan(skb);
411
412 atomic_long_inc(&tunnel->stats.rx_packets);
413 atomic_long_add(length, &tunnel->stats.rx_bytes);
414 atomic_long_inc(&session->stats.rx_packets);
415 atomic_long_add(length, &session->stats.rx_bytes);
416
417 if (L2TP_SKB_CB(skb)->has_seq) {
418 /* Bump our Nr */
419 session->nr++;
420 session->nr &= session->nr_max;
421
422 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
423 session->name, session->nr);
424 }
425
426 /* call private receive handler */
427 if (session->recv_skb != NULL)
428 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
429 else
430 kfree_skb(skb);
431
432 if (session->deref)
433 (*session->deref)(session);
434 }
435
436 /* Dequeue skbs from the session's reorder_q, subject to packet order.
437 * Skbs that have been in the queue for too long are simply discarded.
438 */
439 static void l2tp_recv_dequeue(struct l2tp_session *session)
440 {
441 struct sk_buff *skb;
442 struct sk_buff *tmp;
443
444 /* If the pkt at the head of the queue has the nr that we
445 * expect to send up next, dequeue it and any other
446 * in-sequence packets behind it.
447 */
448 start:
449 spin_lock_bh(&session->reorder_q.lock);
450 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
451 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
452 atomic_long_inc(&session->stats.rx_seq_discards);
453 atomic_long_inc(&session->stats.rx_errors);
454 l2tp_dbg(session, L2TP_MSG_SEQ,
455 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
456 session->name, L2TP_SKB_CB(skb)->ns,
457 L2TP_SKB_CB(skb)->length, session->nr,
458 skb_queue_len(&session->reorder_q));
459 session->reorder_skip = 1;
460 __skb_unlink(skb, &session->reorder_q);
461 kfree_skb(skb);
462 if (session->deref)
463 (*session->deref)(session);
464 continue;
465 }
466
467 if (L2TP_SKB_CB(skb)->has_seq) {
468 if (session->reorder_skip) {
469 l2tp_dbg(session, L2TP_MSG_SEQ,
470 "%s: advancing nr to next pkt: %u -> %u",
471 session->name, session->nr,
472 L2TP_SKB_CB(skb)->ns);
473 session->reorder_skip = 0;
474 session->nr = L2TP_SKB_CB(skb)->ns;
475 }
476 if (L2TP_SKB_CB(skb)->ns != session->nr) {
477 l2tp_dbg(session, L2TP_MSG_SEQ,
478 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
479 session->name, L2TP_SKB_CB(skb)->ns,
480 L2TP_SKB_CB(skb)->length, session->nr,
481 skb_queue_len(&session->reorder_q));
482 goto out;
483 }
484 }
485 __skb_unlink(skb, &session->reorder_q);
486
487 /* Process the skb. We release the queue lock while we
488 * do so to let other contexts process the queue.
489 */
490 spin_unlock_bh(&session->reorder_q.lock);
491 l2tp_recv_dequeue_skb(session, skb);
492 goto start;
493 }
494
495 out:
496 spin_unlock_bh(&session->reorder_q.lock);
497 }
498
499 static inline int l2tp_verify_udp_checksum(struct sock *sk,
500 struct sk_buff *skb)
501 {
502 struct udphdr *uh = udp_hdr(skb);
503 u16 ulen = ntohs(uh->len);
504 __wsum psum;
505
506 if (sk->sk_no_check || skb_csum_unnecessary(skb))
507 return 0;
508
509 #if IS_ENABLED(CONFIG_IPV6)
510 if (sk->sk_family == PF_INET6 && !l2tp_tunnel(sk)->v4mapped) {
511 if (!uh->check) {
512 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
513 return 1;
514 }
515 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
516 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
517 &ipv6_hdr(skb)->daddr, ulen,
518 IPPROTO_UDP, skb->csum)) {
519 skb->ip_summed = CHECKSUM_UNNECESSARY;
520 return 0;
521 }
522 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
523 &ipv6_hdr(skb)->daddr,
524 skb->len, IPPROTO_UDP,
525 0));
526 } else
527 #endif
528 {
529 struct inet_sock *inet;
530 if (!uh->check)
531 return 0;
532 inet = inet_sk(sk);
533 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
534 ulen, IPPROTO_UDP, 0);
535
536 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
537 !csum_fold(csum_add(psum, skb->csum)))
538 return 0;
539 skb->csum = psum;
540 }
541
542 return __skb_checksum_complete(skb);
543 }
544
545 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
546 {
547 u32 nws;
548
549 if (nr >= session->nr)
550 nws = nr - session->nr;
551 else
552 nws = (session->nr_max + 1) - (session->nr - nr);
553
554 return nws < session->nr_window_size;
555 }
556
557 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
558 * acceptable, else non-zero.
559 */
560 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
561 {
562 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
563 /* Packet sequence number is outside allowed window.
564 * Discard it.
565 */
566 l2tp_dbg(session, L2TP_MSG_SEQ,
567 "%s: pkt %u len %d discarded, outside window, nr=%u\n",
568 session->name, L2TP_SKB_CB(skb)->ns,
569 L2TP_SKB_CB(skb)->length, session->nr);
570 goto discard;
571 }
572
573 if (session->reorder_timeout != 0) {
574 /* Packet reordering enabled. Add skb to session's
575 * reorder queue, in order of ns.
576 */
577 l2tp_recv_queue_skb(session, skb);
578 goto out;
579 }
580
581 /* Packet reordering disabled. Discard out-of-sequence packets, while
582 * tracking the number if in-sequence packets after the first OOS packet
583 * is seen. After nr_oos_count_max in-sequence packets, reset the
584 * sequence number to re-enable packet reception.
585 */
586 if (L2TP_SKB_CB(skb)->ns == session->nr) {
587 skb_queue_tail(&session->reorder_q, skb);
588 } else {
589 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
590 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
591
592 if (nr_oos == nr_next)
593 session->nr_oos_count++;
594 else
595 session->nr_oos_count = 0;
596
597 session->nr_oos = nr_oos;
598 if (session->nr_oos_count > session->nr_oos_count_max) {
599 session->reorder_skip = 1;
600 l2tp_dbg(session, L2TP_MSG_SEQ,
601 "%s: %d oos packets received. Resetting sequence numbers\n",
602 session->name, session->nr_oos_count);
603 }
604 if (!session->reorder_skip) {
605 atomic_long_inc(&session->stats.rx_seq_discards);
606 l2tp_dbg(session, L2TP_MSG_SEQ,
607 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
608 session->name, L2TP_SKB_CB(skb)->ns,
609 L2TP_SKB_CB(skb)->length, session->nr,
610 skb_queue_len(&session->reorder_q));
611 goto discard;
612 }
613 skb_queue_tail(&session->reorder_q, skb);
614 }
615
616 out:
617 return 0;
618
619 discard:
620 return 1;
621 }
622
623 /* Do receive processing of L2TP data frames. We handle both L2TPv2
624 * and L2TPv3 data frames here.
625 *
626 * L2TPv2 Data Message Header
627 *
628 * 0 1 2 3
629 * 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
630 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
631 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
632 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
633 * | Tunnel ID | Session ID |
634 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
635 * | Ns (opt) | Nr (opt) |
636 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
637 * | Offset Size (opt) | Offset pad... (opt)
638 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
639 *
640 * Data frames are marked by T=0. All other fields are the same as
641 * those in L2TP control frames.
642 *
643 * L2TPv3 Data Message Header
644 *
645 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
646 * | L2TP Session Header |
647 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
648 * | L2-Specific Sublayer |
649 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
650 * | Tunnel Payload ...
651 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
652 *
653 * L2TPv3 Session Header Over IP
654 *
655 * 0 1 2 3
656 * 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
657 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
658 * | Session ID |
659 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
660 * | Cookie (optional, maximum 64 bits)...
661 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
662 * |
663 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
664 *
665 * L2TPv3 L2-Specific Sublayer Format
666 *
667 * 0 1 2 3
668 * 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
669 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
670 * |x|S|x|x|x|x|x|x| Sequence Number |
671 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
672 *
673 * Cookie value, sublayer format and offset (pad) are negotiated with
674 * the peer when the session is set up. Unlike L2TPv2, we do not need
675 * to parse the packet header to determine if optional fields are
676 * present.
677 *
678 * Caller must already have parsed the frame and determined that it is
679 * a data (not control) frame before coming here. Fields up to the
680 * session-id have already been parsed and ptr points to the data
681 * after the session-id.
682 */
683 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
684 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
685 int length, int (*payload_hook)(struct sk_buff *skb))
686 {
687 struct l2tp_tunnel *tunnel = session->tunnel;
688 int offset;
689 u32 ns, nr;
690
691 /* The ref count is increased since we now hold a pointer to
692 * the session. Take care to decrement the refcnt when exiting
693 * this function from now on...
694 */
695 l2tp_session_inc_refcount(session);
696 if (session->ref)
697 (*session->ref)(session);
698
699 /* Parse and check optional cookie */
700 if (session->peer_cookie_len > 0) {
701 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
702 l2tp_info(tunnel, L2TP_MSG_DATA,
703 "%s: cookie mismatch (%u/%u). Discarding.\n",
704 tunnel->name, tunnel->tunnel_id,
705 session->session_id);
706 atomic_long_inc(&session->stats.rx_cookie_discards);
707 goto discard;
708 }
709 ptr += session->peer_cookie_len;
710 }
711
712 /* Handle the optional sequence numbers. Sequence numbers are
713 * in different places for L2TPv2 and L2TPv3.
714 *
715 * If we are the LAC, enable/disable sequence numbers under
716 * the control of the LNS. If no sequence numbers present but
717 * we were expecting them, discard frame.
718 */
719 ns = nr = 0;
720 L2TP_SKB_CB(skb)->has_seq = 0;
721 if (tunnel->version == L2TP_HDR_VER_2) {
722 if (hdrflags & L2TP_HDRFLAG_S) {
723 ns = ntohs(*(__be16 *) ptr);
724 ptr += 2;
725 nr = ntohs(*(__be16 *) ptr);
726 ptr += 2;
727
728 /* Store L2TP info in the skb */
729 L2TP_SKB_CB(skb)->ns = ns;
730 L2TP_SKB_CB(skb)->has_seq = 1;
731
732 l2tp_dbg(session, L2TP_MSG_SEQ,
733 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
734 session->name, ns, nr, session->nr);
735 }
736 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
737 u32 l2h = ntohl(*(__be32 *) ptr);
738
739 if (l2h & 0x40000000) {
740 ns = l2h & 0x00ffffff;
741
742 /* Store L2TP info in the skb */
743 L2TP_SKB_CB(skb)->ns = ns;
744 L2TP_SKB_CB(skb)->has_seq = 1;
745
746 l2tp_dbg(session, L2TP_MSG_SEQ,
747 "%s: recv data ns=%u, session nr=%u\n",
748 session->name, ns, session->nr);
749 }
750 }
751
752 /* Advance past L2-specific header, if present */
753 ptr += session->l2specific_len;
754
755 if (L2TP_SKB_CB(skb)->has_seq) {
756 /* Received a packet with sequence numbers. If we're the LNS,
757 * check if we sre sending sequence numbers and if not,
758 * configure it so.
759 */
760 if ((!session->lns_mode) && (!session->send_seq)) {
761 l2tp_info(session, L2TP_MSG_SEQ,
762 "%s: requested to enable seq numbers by LNS\n",
763 session->name);
764 session->send_seq = -1;
765 l2tp_session_set_header_len(session, tunnel->version);
766 }
767 } else {
768 /* No sequence numbers.
769 * If user has configured mandatory sequence numbers, discard.
770 */
771 if (session->recv_seq) {
772 l2tp_warn(session, L2TP_MSG_SEQ,
773 "%s: recv data has no seq numbers when required. Discarding.\n",
774 session->name);
775 atomic_long_inc(&session->stats.rx_seq_discards);
776 goto discard;
777 }
778
779 /* If we're the LAC and we're sending sequence numbers, the
780 * LNS has requested that we no longer send sequence numbers.
781 * If we're the LNS and we're sending sequence numbers, the
782 * LAC is broken. Discard the frame.
783 */
784 if ((!session->lns_mode) && (session->send_seq)) {
785 l2tp_info(session, L2TP_MSG_SEQ,
786 "%s: requested to disable seq numbers by LNS\n",
787 session->name);
788 session->send_seq = 0;
789 l2tp_session_set_header_len(session, tunnel->version);
790 } else if (session->send_seq) {
791 l2tp_warn(session, L2TP_MSG_SEQ,
792 "%s: recv data has no seq numbers when required. Discarding.\n",
793 session->name);
794 atomic_long_inc(&session->stats.rx_seq_discards);
795 goto discard;
796 }
797 }
798
799 /* Session data offset is handled differently for L2TPv2 and
800 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
801 * the header. For L2TPv3, the offset is negotiated using AVPs
802 * in the session setup control protocol.
803 */
804 if (tunnel->version == L2TP_HDR_VER_2) {
805 /* If offset bit set, skip it. */
806 if (hdrflags & L2TP_HDRFLAG_O) {
807 offset = ntohs(*(__be16 *)ptr);
808 ptr += 2 + offset;
809 }
810 } else
811 ptr += session->offset;
812
813 offset = ptr - optr;
814 if (!pskb_may_pull(skb, offset))
815 goto discard;
816
817 __skb_pull(skb, offset);
818
819 /* If caller wants to process the payload before we queue the
820 * packet, do so now.
821 */
822 if (payload_hook)
823 if ((*payload_hook)(skb))
824 goto discard;
825
826 /* Prepare skb for adding to the session's reorder_q. Hold
827 * packets for max reorder_timeout or 1 second if not
828 * reordering.
829 */
830 L2TP_SKB_CB(skb)->length = length;
831 L2TP_SKB_CB(skb)->expires = jiffies +
832 (session->reorder_timeout ? session->reorder_timeout : HZ);
833
834 /* Add packet to the session's receive queue. Reordering is done here, if
835 * enabled. Saved L2TP protocol info is stored in skb->sb[].
836 */
837 if (L2TP_SKB_CB(skb)->has_seq) {
838 if (l2tp_recv_data_seq(session, skb))
839 goto discard;
840 } else {
841 /* No sequence numbers. Add the skb to the tail of the
842 * reorder queue. This ensures that it will be
843 * delivered after all previous sequenced skbs.
844 */
845 skb_queue_tail(&session->reorder_q, skb);
846 }
847
848 /* Try to dequeue as many skbs from reorder_q as we can. */
849 l2tp_recv_dequeue(session);
850
851 l2tp_session_dec_refcount(session);
852
853 return;
854
855 discard:
856 atomic_long_inc(&session->stats.rx_errors);
857 kfree_skb(skb);
858
859 if (session->deref)
860 (*session->deref)(session);
861
862 l2tp_session_dec_refcount(session);
863 }
864 EXPORT_SYMBOL(l2tp_recv_common);
865
866 /* Drop skbs from the session's reorder_q
867 */
868 int l2tp_session_queue_purge(struct l2tp_session *session)
869 {
870 struct sk_buff *skb = NULL;
871 BUG_ON(!session);
872 BUG_ON(session->magic != L2TP_SESSION_MAGIC);
873 while ((skb = skb_dequeue(&session->reorder_q))) {
874 atomic_long_inc(&session->stats.rx_errors);
875 kfree_skb(skb);
876 if (session->deref)
877 (*session->deref)(session);
878 }
879 return 0;
880 }
881 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
882
883 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
884 * here. The skb is not on a list when we get here.
885 * Returns 0 if the packet was a data packet and was successfully passed on.
886 * Returns 1 if the packet was not a good data packet and could not be
887 * forwarded. All such packets are passed up to userspace to deal with.
888 */
889 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
890 int (*payload_hook)(struct sk_buff *skb))
891 {
892 struct l2tp_session *session = NULL;
893 unsigned char *ptr, *optr;
894 u16 hdrflags;
895 u32 tunnel_id, session_id;
896 u16 version;
897 int length;
898
899 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
900 goto discard_bad_csum;
901
902 /* UDP always verifies the packet length. */
903 __skb_pull(skb, sizeof(struct udphdr));
904
905 /* Short packet? */
906 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
907 l2tp_info(tunnel, L2TP_MSG_DATA,
908 "%s: recv short packet (len=%d)\n",
909 tunnel->name, skb->len);
910 goto error;
911 }
912
913 /* Trace packet contents, if enabled */
914 if (tunnel->debug & L2TP_MSG_DATA) {
915 length = min(32u, skb->len);
916 if (!pskb_may_pull(skb, length))
917 goto error;
918
919 pr_debug("%s: recv\n", tunnel->name);
920 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
921 }
922
923 /* Point to L2TP header */
924 optr = ptr = skb->data;
925
926 /* Get L2TP header flags */
927 hdrflags = ntohs(*(__be16 *) ptr);
928
929 /* Check protocol version */
930 version = hdrflags & L2TP_HDR_VER_MASK;
931 if (version != tunnel->version) {
932 l2tp_info(tunnel, L2TP_MSG_DATA,
933 "%s: recv protocol version mismatch: got %d expected %d\n",
934 tunnel->name, version, tunnel->version);
935 goto error;
936 }
937
938 /* Get length of L2TP packet */
939 length = skb->len;
940
941 /* If type is control packet, it is handled by userspace. */
942 if (hdrflags & L2TP_HDRFLAG_T) {
943 l2tp_dbg(tunnel, L2TP_MSG_DATA,
944 "%s: recv control packet, len=%d\n",
945 tunnel->name, length);
946 goto error;
947 }
948
949 /* Skip flags */
950 ptr += 2;
951
952 if (tunnel->version == L2TP_HDR_VER_2) {
953 /* If length is present, skip it */
954 if (hdrflags & L2TP_HDRFLAG_L)
955 ptr += 2;
956
957 /* Extract tunnel and session ID */
958 tunnel_id = ntohs(*(__be16 *) ptr);
959 ptr += 2;
960 session_id = ntohs(*(__be16 *) ptr);
961 ptr += 2;
962 } else {
963 ptr += 2; /* skip reserved bits */
964 tunnel_id = tunnel->tunnel_id;
965 session_id = ntohl(*(__be32 *) ptr);
966 ptr += 4;
967 }
968
969 /* Find the session context */
970 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
971 if (!session || !session->recv_skb) {
972 /* Not found? Pass to userspace to deal with */
973 l2tp_info(tunnel, L2TP_MSG_DATA,
974 "%s: no session found (%u/%u). Passing up.\n",
975 tunnel->name, tunnel_id, session_id);
976 goto error;
977 }
978
979 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
980
981 return 0;
982
983 discard_bad_csum:
984 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
985 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
986 atomic_long_inc(&tunnel->stats.rx_errors);
987 kfree_skb(skb);
988
989 return 0;
990
991 error:
992 /* Put UDP header back */
993 __skb_push(skb, sizeof(struct udphdr));
994
995 return 1;
996 }
997
998 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
999 * Return codes:
1000 * 0 : success.
1001 * <0: error
1002 * >0: skb should be passed up to userspace as UDP.
1003 */
1004 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1005 {
1006 struct l2tp_tunnel *tunnel;
1007
1008 tunnel = l2tp_sock_to_tunnel(sk);
1009 if (tunnel == NULL)
1010 goto pass_up;
1011
1012 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1013 tunnel->name, skb->len);
1014
1015 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1016 goto pass_up_put;
1017
1018 sock_put(sk);
1019 return 0;
1020
1021 pass_up_put:
1022 sock_put(sk);
1023 pass_up:
1024 return 1;
1025 }
1026 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1027
1028 /************************************************************************
1029 * Transmit handling
1030 ***********************************************************************/
1031
1032 /* Build an L2TP header for the session into the buffer provided.
1033 */
1034 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1035 {
1036 struct l2tp_tunnel *tunnel = session->tunnel;
1037 __be16 *bufp = buf;
1038 __be16 *optr = buf;
1039 u16 flags = L2TP_HDR_VER_2;
1040 u32 tunnel_id = tunnel->peer_tunnel_id;
1041 u32 session_id = session->peer_session_id;
1042
1043 if (session->send_seq)
1044 flags |= L2TP_HDRFLAG_S;
1045
1046 /* Setup L2TP header. */
1047 *bufp++ = htons(flags);
1048 *bufp++ = htons(tunnel_id);
1049 *bufp++ = htons(session_id);
1050 if (session->send_seq) {
1051 *bufp++ = htons(session->ns);
1052 *bufp++ = 0;
1053 session->ns++;
1054 session->ns &= 0xffff;
1055 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1056 session->name, session->ns);
1057 }
1058
1059 return bufp - optr;
1060 }
1061
1062 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1063 {
1064 struct l2tp_tunnel *tunnel = session->tunnel;
1065 char *bufp = buf;
1066 char *optr = bufp;
1067
1068 /* Setup L2TP header. The header differs slightly for UDP and
1069 * IP encapsulations. For UDP, there is 4 bytes of flags.
1070 */
1071 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1072 u16 flags = L2TP_HDR_VER_3;
1073 *((__be16 *) bufp) = htons(flags);
1074 bufp += 2;
1075 *((__be16 *) bufp) = 0;
1076 bufp += 2;
1077 }
1078
1079 *((__be32 *) bufp) = htonl(session->peer_session_id);
1080 bufp += 4;
1081 if (session->cookie_len) {
1082 memcpy(bufp, &session->cookie[0], session->cookie_len);
1083 bufp += session->cookie_len;
1084 }
1085 if (session->l2specific_len) {
1086 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1087 u32 l2h = 0;
1088 if (session->send_seq) {
1089 l2h = 0x40000000 | session->ns;
1090 session->ns++;
1091 session->ns &= 0xffffff;
1092 l2tp_dbg(session, L2TP_MSG_SEQ,
1093 "%s: updated ns to %u\n",
1094 session->name, session->ns);
1095 }
1096
1097 *((__be32 *) bufp) = htonl(l2h);
1098 }
1099 bufp += session->l2specific_len;
1100 }
1101 if (session->offset)
1102 bufp += session->offset;
1103
1104 return bufp - optr;
1105 }
1106
1107 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1108 struct flowi *fl, size_t data_len)
1109 {
1110 struct l2tp_tunnel *tunnel = session->tunnel;
1111 unsigned int len = skb->len;
1112 int error;
1113
1114 /* Debug */
1115 if (session->send_seq)
1116 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1117 session->name, data_len, session->ns - 1);
1118 else
1119 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1120 session->name, data_len);
1121
1122 if (session->debug & L2TP_MSG_DATA) {
1123 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1124 unsigned char *datap = skb->data + uhlen;
1125
1126 pr_debug("%s: xmit\n", session->name);
1127 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1128 datap, min_t(size_t, 32, len - uhlen));
1129 }
1130
1131 /* Queue the packet to IP for output */
1132 skb->local_df = 1;
1133 #if IS_ENABLED(CONFIG_IPV6)
1134 if (skb->sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1135 error = inet6_csk_xmit(skb, NULL);
1136 else
1137 #endif
1138 error = ip_queue_xmit(skb, fl);
1139
1140 /* Update stats */
1141 if (error >= 0) {
1142 atomic_long_inc(&tunnel->stats.tx_packets);
1143 atomic_long_add(len, &tunnel->stats.tx_bytes);
1144 atomic_long_inc(&session->stats.tx_packets);
1145 atomic_long_add(len, &session->stats.tx_bytes);
1146 } else {
1147 atomic_long_inc(&tunnel->stats.tx_errors);
1148 atomic_long_inc(&session->stats.tx_errors);
1149 }
1150
1151 return 0;
1152 }
1153
1154 /* Automatically called when the skb is freed.
1155 */
1156 static void l2tp_sock_wfree(struct sk_buff *skb)
1157 {
1158 sock_put(skb->sk);
1159 }
1160
1161 /* For data skbs that we transmit, we associate with the tunnel socket
1162 * but don't do accounting.
1163 */
1164 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1165 {
1166 sock_hold(sk);
1167 skb->sk = sk;
1168 skb->destructor = l2tp_sock_wfree;
1169 }
1170
1171 #if IS_ENABLED(CONFIG_IPV6)
1172 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1173 int udp_len)
1174 {
1175 struct ipv6_pinfo *np = inet6_sk(sk);
1176 struct udphdr *uh = udp_hdr(skb);
1177
1178 if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1179 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1180 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1181 skb->ip_summed = CHECKSUM_UNNECESSARY;
1182 uh->check = csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr, udp_len,
1183 IPPROTO_UDP, csum);
1184 if (uh->check == 0)
1185 uh->check = CSUM_MANGLED_0;
1186 } else {
1187 skb->ip_summed = CHECKSUM_PARTIAL;
1188 skb->csum_start = skb_transport_header(skb) - skb->head;
1189 skb->csum_offset = offsetof(struct udphdr, check);
1190 uh->check = ~csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr,
1191 udp_len, IPPROTO_UDP, 0);
1192 }
1193 }
1194 #endif
1195
1196 /* If caller requires the skb to have a ppp header, the header must be
1197 * inserted in the skb data before calling this function.
1198 */
1199 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1200 {
1201 int data_len = skb->len;
1202 struct l2tp_tunnel *tunnel = session->tunnel;
1203 struct sock *sk = tunnel->sock;
1204 struct flowi *fl;
1205 struct udphdr *uh;
1206 struct inet_sock *inet;
1207 __wsum csum;
1208 int headroom;
1209 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1210 int udp_len;
1211 int ret = NET_XMIT_SUCCESS;
1212
1213 /* Check that there's enough headroom in the skb to insert IP,
1214 * UDP and L2TP headers. If not enough, expand it to
1215 * make room. Adjust truesize.
1216 */
1217 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1218 uhlen + hdr_len;
1219 if (skb_cow_head(skb, headroom)) {
1220 kfree_skb(skb);
1221 return NET_XMIT_DROP;
1222 }
1223
1224 skb_orphan(skb);
1225 /* Setup L2TP header */
1226 session->build_header(session, __skb_push(skb, hdr_len));
1227
1228 /* Reset skb netfilter state */
1229 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1230 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1231 IPSKB_REROUTED);
1232 nf_reset(skb);
1233
1234 bh_lock_sock(sk);
1235 if (sock_owned_by_user(sk)) {
1236 kfree_skb(skb);
1237 ret = NET_XMIT_DROP;
1238 goto out_unlock;
1239 }
1240
1241 /* Get routing info from the tunnel socket */
1242 skb_dst_drop(skb);
1243 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1244
1245 inet = inet_sk(sk);
1246 fl = &inet->cork.fl;
1247 switch (tunnel->encap) {
1248 case L2TP_ENCAPTYPE_UDP:
1249 /* Setup UDP header */
1250 __skb_push(skb, sizeof(*uh));
1251 skb_reset_transport_header(skb);
1252 uh = udp_hdr(skb);
1253 uh->source = inet->inet_sport;
1254 uh->dest = inet->inet_dport;
1255 udp_len = uhlen + hdr_len + data_len;
1256 uh->len = htons(udp_len);
1257 uh->check = 0;
1258
1259 /* Calculate UDP checksum if configured to do so */
1260 #if IS_ENABLED(CONFIG_IPV6)
1261 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1262 l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1263 else
1264 #endif
1265 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1266 skb->ip_summed = CHECKSUM_NONE;
1267 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1268 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1269 skb->ip_summed = CHECKSUM_COMPLETE;
1270 csum = skb_checksum(skb, 0, udp_len, 0);
1271 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1272 inet->inet_daddr,
1273 udp_len, IPPROTO_UDP, csum);
1274 if (uh->check == 0)
1275 uh->check = CSUM_MANGLED_0;
1276 } else {
1277 skb->ip_summed = CHECKSUM_PARTIAL;
1278 skb->csum_start = skb_transport_header(skb) - skb->head;
1279 skb->csum_offset = offsetof(struct udphdr, check);
1280 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1281 inet->inet_daddr,
1282 udp_len, IPPROTO_UDP, 0);
1283 }
1284 break;
1285
1286 case L2TP_ENCAPTYPE_IP:
1287 break;
1288 }
1289
1290 l2tp_skb_set_owner_w(skb, sk);
1291
1292 l2tp_xmit_core(session, skb, fl, data_len);
1293 out_unlock:
1294 bh_unlock_sock(sk);
1295
1296 return ret;
1297 }
1298 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1299
1300 /*****************************************************************************
1301 * Tinnel and session create/destroy.
1302 *****************************************************************************/
1303
1304 /* Tunnel socket destruct hook.
1305 * The tunnel context is deleted only when all session sockets have been
1306 * closed.
1307 */
1308 static void l2tp_tunnel_destruct(struct sock *sk)
1309 {
1310 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1311 struct l2tp_net *pn;
1312
1313 if (tunnel == NULL)
1314 goto end;
1315
1316 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1317
1318
1319 /* Disable udp encapsulation */
1320 switch (tunnel->encap) {
1321 case L2TP_ENCAPTYPE_UDP:
1322 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1323 (udp_sk(sk))->encap_type = 0;
1324 (udp_sk(sk))->encap_rcv = NULL;
1325 (udp_sk(sk))->encap_destroy = NULL;
1326 break;
1327 case L2TP_ENCAPTYPE_IP:
1328 break;
1329 }
1330
1331 /* Remove hooks into tunnel socket */
1332 sk->sk_destruct = tunnel->old_sk_destruct;
1333 sk->sk_user_data = NULL;
1334 tunnel->sock = NULL;
1335
1336 /* Remove the tunnel struct from the tunnel list */
1337 pn = l2tp_pernet(tunnel->l2tp_net);
1338 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1339 list_del_rcu(&tunnel->list);
1340 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1341 atomic_dec(&l2tp_tunnel_count);
1342
1343 l2tp_tunnel_closeall(tunnel);
1344 l2tp_tunnel_dec_refcount(tunnel);
1345
1346 /* Call the original destructor */
1347 if (sk->sk_destruct)
1348 (*sk->sk_destruct)(sk);
1349 end:
1350 return;
1351 }
1352
1353 /* When the tunnel is closed, all the attached sessions need to go too.
1354 */
1355 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1356 {
1357 int hash;
1358 struct hlist_node *walk;
1359 struct hlist_node *tmp;
1360 struct l2tp_session *session;
1361
1362 BUG_ON(tunnel == NULL);
1363
1364 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1365 tunnel->name);
1366
1367 write_lock_bh(&tunnel->hlist_lock);
1368 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1369 again:
1370 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1371 session = hlist_entry(walk, struct l2tp_session, hlist);
1372
1373 l2tp_info(session, L2TP_MSG_CONTROL,
1374 "%s: closing session\n", session->name);
1375
1376 hlist_del_init(&session->hlist);
1377
1378 if (session->ref != NULL)
1379 (*session->ref)(session);
1380
1381 write_unlock_bh(&tunnel->hlist_lock);
1382
1383 __l2tp_session_unhash(session);
1384 l2tp_session_queue_purge(session);
1385
1386 if (session->session_close != NULL)
1387 (*session->session_close)(session);
1388
1389 if (session->deref != NULL)
1390 (*session->deref)(session);
1391
1392 l2tp_session_dec_refcount(session);
1393
1394 write_lock_bh(&tunnel->hlist_lock);
1395
1396 /* Now restart from the beginning of this hash
1397 * chain. We always remove a session from the
1398 * list so we are guaranteed to make forward
1399 * progress.
1400 */
1401 goto again;
1402 }
1403 }
1404 write_unlock_bh(&tunnel->hlist_lock);
1405 }
1406 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1407
1408 /* Tunnel socket destroy hook for UDP encapsulation */
1409 static void l2tp_udp_encap_destroy(struct sock *sk)
1410 {
1411 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1412 if (tunnel) {
1413 l2tp_tunnel_closeall(tunnel);
1414 sock_put(sk);
1415 }
1416 }
1417
1418 /* Really kill the tunnel.
1419 * Come here only when all sessions have been cleared from the tunnel.
1420 */
1421 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1422 {
1423 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1424 BUG_ON(tunnel->sock != NULL);
1425 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1426 kfree_rcu(tunnel, rcu);
1427 }
1428
1429 /* Workqueue tunnel deletion function */
1430 static void l2tp_tunnel_del_work(struct work_struct *work)
1431 {
1432 struct l2tp_tunnel *tunnel = NULL;
1433 struct socket *sock = NULL;
1434 struct sock *sk = NULL;
1435
1436 tunnel = container_of(work, struct l2tp_tunnel, del_work);
1437 sk = l2tp_tunnel_sock_lookup(tunnel);
1438 if (!sk)
1439 return;
1440
1441 sock = sk->sk_socket;
1442
1443 /* If the tunnel socket was created by userspace, then go through the
1444 * inet layer to shut the socket down, and let userspace close it.
1445 * Otherwise, if we created the socket directly within the kernel, use
1446 * the sk API to release it here.
1447 * In either case the tunnel resources are freed in the socket
1448 * destructor when the tunnel socket goes away.
1449 */
1450 if (tunnel->fd >= 0) {
1451 if (sock)
1452 inet_shutdown(sock, 2);
1453 } else {
1454 if (sock)
1455 kernel_sock_shutdown(sock, SHUT_RDWR);
1456 sk_release_kernel(sk);
1457 }
1458
1459 l2tp_tunnel_sock_put(sk);
1460 }
1461
1462 /* Create a socket for the tunnel, if one isn't set up by
1463 * userspace. This is used for static tunnels where there is no
1464 * managing L2TP daemon.
1465 *
1466 * Since we don't want these sockets to keep a namespace alive by
1467 * themselves, we drop the socket's namespace refcount after creation.
1468 * These sockets are freed when the namespace exits using the pernet
1469 * exit hook.
1470 */
1471 static int l2tp_tunnel_sock_create(struct net *net,
1472 u32 tunnel_id,
1473 u32 peer_tunnel_id,
1474 struct l2tp_tunnel_cfg *cfg,
1475 struct socket **sockp)
1476 {
1477 int err = -EINVAL;
1478 struct socket *sock = NULL;
1479 struct sockaddr_in udp_addr = {0};
1480 struct sockaddr_l2tpip ip_addr = {0};
1481 #if IS_ENABLED(CONFIG_IPV6)
1482 struct sockaddr_in6 udp6_addr = {0};
1483 struct sockaddr_l2tpip6 ip6_addr = {0};
1484 #endif
1485
1486 switch (cfg->encap) {
1487 case L2TP_ENCAPTYPE_UDP:
1488 #if IS_ENABLED(CONFIG_IPV6)
1489 if (cfg->local_ip6 && cfg->peer_ip6) {
1490 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1491 if (err < 0)
1492 goto out;
1493
1494 sk_change_net(sock->sk, net);
1495
1496 udp6_addr.sin6_family = AF_INET6;
1497 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1498 sizeof(udp6_addr.sin6_addr));
1499 udp6_addr.sin6_port = htons(cfg->local_udp_port);
1500 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1501 sizeof(udp6_addr));
1502 if (err < 0)
1503 goto out;
1504
1505 udp6_addr.sin6_family = AF_INET6;
1506 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1507 sizeof(udp6_addr.sin6_addr));
1508 udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1509 err = kernel_connect(sock,
1510 (struct sockaddr *) &udp6_addr,
1511 sizeof(udp6_addr), 0);
1512 if (err < 0)
1513 goto out;
1514 } else
1515 #endif
1516 {
1517 err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1518 if (err < 0)
1519 goto out;
1520
1521 sk_change_net(sock->sk, net);
1522
1523 udp_addr.sin_family = AF_INET;
1524 udp_addr.sin_addr = cfg->local_ip;
1525 udp_addr.sin_port = htons(cfg->local_udp_port);
1526 err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1527 sizeof(udp_addr));
1528 if (err < 0)
1529 goto out;
1530
1531 udp_addr.sin_family = AF_INET;
1532 udp_addr.sin_addr = cfg->peer_ip;
1533 udp_addr.sin_port = htons(cfg->peer_udp_port);
1534 err = kernel_connect(sock,
1535 (struct sockaddr *) &udp_addr,
1536 sizeof(udp_addr), 0);
1537 if (err < 0)
1538 goto out;
1539 }
1540
1541 if (!cfg->use_udp_checksums)
1542 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1543
1544 break;
1545
1546 case L2TP_ENCAPTYPE_IP:
1547 #if IS_ENABLED(CONFIG_IPV6)
1548 if (cfg->local_ip6 && cfg->peer_ip6) {
1549 err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1550 IPPROTO_L2TP, &sock);
1551 if (err < 0)
1552 goto out;
1553
1554 sk_change_net(sock->sk, net);
1555
1556 ip6_addr.l2tp_family = AF_INET6;
1557 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1558 sizeof(ip6_addr.l2tp_addr));
1559 ip6_addr.l2tp_conn_id = tunnel_id;
1560 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1561 sizeof(ip6_addr));
1562 if (err < 0)
1563 goto out;
1564
1565 ip6_addr.l2tp_family = AF_INET6;
1566 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1567 sizeof(ip6_addr.l2tp_addr));
1568 ip6_addr.l2tp_conn_id = peer_tunnel_id;
1569 err = kernel_connect(sock,
1570 (struct sockaddr *) &ip6_addr,
1571 sizeof(ip6_addr), 0);
1572 if (err < 0)
1573 goto out;
1574 } else
1575 #endif
1576 {
1577 err = sock_create_kern(AF_INET, SOCK_DGRAM,
1578 IPPROTO_L2TP, &sock);
1579 if (err < 0)
1580 goto out;
1581
1582 sk_change_net(sock->sk, net);
1583
1584 ip_addr.l2tp_family = AF_INET;
1585 ip_addr.l2tp_addr = cfg->local_ip;
1586 ip_addr.l2tp_conn_id = tunnel_id;
1587 err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1588 sizeof(ip_addr));
1589 if (err < 0)
1590 goto out;
1591
1592 ip_addr.l2tp_family = AF_INET;
1593 ip_addr.l2tp_addr = cfg->peer_ip;
1594 ip_addr.l2tp_conn_id = peer_tunnel_id;
1595 err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1596 sizeof(ip_addr), 0);
1597 if (err < 0)
1598 goto out;
1599 }
1600 break;
1601
1602 default:
1603 goto out;
1604 }
1605
1606 out:
1607 *sockp = sock;
1608 if ((err < 0) && sock) {
1609 kernel_sock_shutdown(sock, SHUT_RDWR);
1610 sk_release_kernel(sock->sk);
1611 *sockp = NULL;
1612 }
1613
1614 return err;
1615 }
1616
1617 static struct lock_class_key l2tp_socket_class;
1618
1619 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)
1620 {
1621 struct l2tp_tunnel *tunnel = NULL;
1622 int err;
1623 struct socket *sock = NULL;
1624 struct sock *sk = NULL;
1625 struct l2tp_net *pn;
1626 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1627
1628 /* Get the tunnel socket from the fd, which was opened by
1629 * the userspace L2TP daemon. If not specified, create a
1630 * kernel socket.
1631 */
1632 if (fd < 0) {
1633 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1634 cfg, &sock);
1635 if (err < 0)
1636 goto err;
1637 } else {
1638 sock = sockfd_lookup(fd, &err);
1639 if (!sock) {
1640 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1641 tunnel_id, fd, err);
1642 err = -EBADF;
1643 goto err;
1644 }
1645
1646 /* Reject namespace mismatches */
1647 if (!net_eq(sock_net(sock->sk), net)) {
1648 pr_err("tunl %u: netns mismatch\n", tunnel_id);
1649 err = -EINVAL;
1650 goto err;
1651 }
1652 }
1653
1654 sk = sock->sk;
1655
1656 if (cfg != NULL)
1657 encap = cfg->encap;
1658
1659 /* Quick sanity checks */
1660 switch (encap) {
1661 case L2TP_ENCAPTYPE_UDP:
1662 err = -EPROTONOSUPPORT;
1663 if (sk->sk_protocol != IPPROTO_UDP) {
1664 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1665 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1666 goto err;
1667 }
1668 break;
1669 case L2TP_ENCAPTYPE_IP:
1670 err = -EPROTONOSUPPORT;
1671 if (sk->sk_protocol != IPPROTO_L2TP) {
1672 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1673 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1674 goto err;
1675 }
1676 break;
1677 }
1678
1679 /* Check if this socket has already been prepped */
1680 tunnel = l2tp_tunnel(sk);
1681 if (tunnel != NULL) {
1682 /* This socket has already been prepped */
1683 err = -EBUSY;
1684 goto err;
1685 }
1686
1687 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1688 if (tunnel == NULL) {
1689 err = -ENOMEM;
1690 goto err;
1691 }
1692
1693 tunnel->version = version;
1694 tunnel->tunnel_id = tunnel_id;
1695 tunnel->peer_tunnel_id = peer_tunnel_id;
1696 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1697
1698 tunnel->magic = L2TP_TUNNEL_MAGIC;
1699 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1700 rwlock_init(&tunnel->hlist_lock);
1701
1702 /* The net we belong to */
1703 tunnel->l2tp_net = net;
1704 pn = l2tp_pernet(net);
1705
1706 if (cfg != NULL)
1707 tunnel->debug = cfg->debug;
1708
1709 #if IS_ENABLED(CONFIG_IPV6)
1710 if (sk->sk_family == PF_INET6) {
1711 struct ipv6_pinfo *np = inet6_sk(sk);
1712
1713 if (ipv6_addr_v4mapped(&np->saddr) &&
1714 ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
1715 struct inet_sock *inet = inet_sk(sk);
1716
1717 tunnel->v4mapped = true;
1718 inet->inet_saddr = np->saddr.s6_addr32[3];
1719 inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
1720 inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
1721 } else {
1722 tunnel->v4mapped = false;
1723 }
1724 }
1725 #endif
1726
1727 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1728 tunnel->encap = encap;
1729 if (encap == L2TP_ENCAPTYPE_UDP) {
1730 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1731 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1732 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1733 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
1734 #if IS_ENABLED(CONFIG_IPV6)
1735 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1736 udpv6_encap_enable();
1737 else
1738 #endif
1739 udp_encap_enable();
1740 }
1741
1742 sk->sk_user_data = tunnel;
1743
1744 /* Hook on the tunnel socket destructor so that we can cleanup
1745 * if the tunnel socket goes away.
1746 */
1747 tunnel->old_sk_destruct = sk->sk_destruct;
1748 sk->sk_destruct = &l2tp_tunnel_destruct;
1749 tunnel->sock = sk;
1750 tunnel->fd = fd;
1751 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1752
1753 sk->sk_allocation = GFP_ATOMIC;
1754
1755 /* Init delete workqueue struct */
1756 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1757
1758 /* Add tunnel to our list */
1759 INIT_LIST_HEAD(&tunnel->list);
1760 atomic_inc(&l2tp_tunnel_count);
1761
1762 /* Bump the reference count. The tunnel context is deleted
1763 * only when this drops to zero. Must be done before list insertion
1764 */
1765 l2tp_tunnel_inc_refcount(tunnel);
1766 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1767 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1768 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1769
1770 err = 0;
1771 err:
1772 if (tunnelp)
1773 *tunnelp = tunnel;
1774
1775 /* If tunnel's socket was created by the kernel, it doesn't
1776 * have a file.
1777 */
1778 if (sock && sock->file)
1779 sockfd_put(sock);
1780
1781 return err;
1782 }
1783 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1784
1785 /* This function is used by the netlink TUNNEL_DELETE command.
1786 */
1787 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1788 {
1789 l2tp_tunnel_closeall(tunnel);
1790 return (false == queue_work(l2tp_wq, &tunnel->del_work));
1791 }
1792 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1793
1794 /* Really kill the session.
1795 */
1796 void l2tp_session_free(struct l2tp_session *session)
1797 {
1798 struct l2tp_tunnel *tunnel = session->tunnel;
1799
1800 BUG_ON(atomic_read(&session->ref_count) != 0);
1801
1802 if (tunnel) {
1803 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1804 if (session->session_id != 0)
1805 atomic_dec(&l2tp_session_count);
1806 sock_put(tunnel->sock);
1807 session->tunnel = NULL;
1808 l2tp_tunnel_dec_refcount(tunnel);
1809 }
1810
1811 kfree(session);
1812
1813 return;
1814 }
1815 EXPORT_SYMBOL_GPL(l2tp_session_free);
1816
1817 /* Remove an l2tp session from l2tp_core's hash lists.
1818 * Provides a tidyup interface for pseudowire code which can't just route all
1819 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1820 * callback.
1821 */
1822 void __l2tp_session_unhash(struct l2tp_session *session)
1823 {
1824 struct l2tp_tunnel *tunnel = session->tunnel;
1825
1826 /* Remove the session from core hashes */
1827 if (tunnel) {
1828 /* Remove from the per-tunnel hash */
1829 write_lock_bh(&tunnel->hlist_lock);
1830 hlist_del_init(&session->hlist);
1831 write_unlock_bh(&tunnel->hlist_lock);
1832
1833 /* For L2TPv3 we have a per-net hash: remove from there, too */
1834 if (tunnel->version != L2TP_HDR_VER_2) {
1835 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1836 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1837 hlist_del_init_rcu(&session->global_hlist);
1838 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1839 synchronize_rcu();
1840 }
1841 }
1842 }
1843 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1844
1845 /* This function is used by the netlink SESSION_DELETE command and by
1846 pseudowire modules.
1847 */
1848 int l2tp_session_delete(struct l2tp_session *session)
1849 {
1850 if (session->ref)
1851 (*session->ref)(session);
1852 __l2tp_session_unhash(session);
1853 l2tp_session_queue_purge(session);
1854 if (session->session_close != NULL)
1855 (*session->session_close)(session);
1856 if (session->deref)
1857 (*session->deref)(session);
1858 l2tp_session_dec_refcount(session);
1859 return 0;
1860 }
1861 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1862
1863 /* We come here whenever a session's send_seq, cookie_len or
1864 * l2specific_len parameters are set.
1865 */
1866 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1867 {
1868 if (version == L2TP_HDR_VER_2) {
1869 session->hdr_len = 6;
1870 if (session->send_seq)
1871 session->hdr_len += 4;
1872 } else {
1873 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1874 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1875 session->hdr_len += 4;
1876 }
1877
1878 }
1879
1880 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)
1881 {
1882 struct l2tp_session *session;
1883
1884 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1885 if (session != NULL) {
1886 session->magic = L2TP_SESSION_MAGIC;
1887 session->tunnel = tunnel;
1888
1889 session->session_id = session_id;
1890 session->peer_session_id = peer_session_id;
1891 session->nr = 0;
1892 if (tunnel->version == L2TP_HDR_VER_2)
1893 session->nr_max = 0xffff;
1894 else
1895 session->nr_max = 0xffffff;
1896 session->nr_window_size = session->nr_max / 2;
1897 session->nr_oos_count_max = 4;
1898
1899 /* Use NR of first received packet */
1900 session->reorder_skip = 1;
1901
1902 sprintf(&session->name[0], "sess %u/%u",
1903 tunnel->tunnel_id, session->session_id);
1904
1905 skb_queue_head_init(&session->reorder_q);
1906
1907 INIT_HLIST_NODE(&session->hlist);
1908 INIT_HLIST_NODE(&session->global_hlist);
1909
1910 /* Inherit debug options from tunnel */
1911 session->debug = tunnel->debug;
1912
1913 if (cfg) {
1914 session->pwtype = cfg->pw_type;
1915 session->debug = cfg->debug;
1916 session->mtu = cfg->mtu;
1917 session->mru = cfg->mru;
1918 session->send_seq = cfg->send_seq;
1919 session->recv_seq = cfg->recv_seq;
1920 session->lns_mode = cfg->lns_mode;
1921 session->reorder_timeout = cfg->reorder_timeout;
1922 session->offset = cfg->offset;
1923 session->l2specific_type = cfg->l2specific_type;
1924 session->l2specific_len = cfg->l2specific_len;
1925 session->cookie_len = cfg->cookie_len;
1926 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1927 session->peer_cookie_len = cfg->peer_cookie_len;
1928 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1929 }
1930
1931 if (tunnel->version == L2TP_HDR_VER_2)
1932 session->build_header = l2tp_build_l2tpv2_header;
1933 else
1934 session->build_header = l2tp_build_l2tpv3_header;
1935
1936 l2tp_session_set_header_len(session, tunnel->version);
1937
1938 /* Bump the reference count. The session context is deleted
1939 * only when this drops to zero.
1940 */
1941 l2tp_session_inc_refcount(session);
1942 l2tp_tunnel_inc_refcount(tunnel);
1943
1944 /* Ensure tunnel socket isn't deleted */
1945 sock_hold(tunnel->sock);
1946
1947 /* Add session to the tunnel's hash list */
1948 write_lock_bh(&tunnel->hlist_lock);
1949 hlist_add_head(&session->hlist,
1950 l2tp_session_id_hash(tunnel, session_id));
1951 write_unlock_bh(&tunnel->hlist_lock);
1952
1953 /* And to the global session list if L2TPv3 */
1954 if (tunnel->version != L2TP_HDR_VER_2) {
1955 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1956
1957 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1958 hlist_add_head_rcu(&session->global_hlist,
1959 l2tp_session_id_hash_2(pn, session_id));
1960 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1961 }
1962
1963 /* Ignore management session in session count value */
1964 if (session->session_id != 0)
1965 atomic_inc(&l2tp_session_count);
1966 }
1967
1968 return session;
1969 }
1970 EXPORT_SYMBOL_GPL(l2tp_session_create);
1971
1972 /*****************************************************************************
1973 * Init and cleanup
1974 *****************************************************************************/
1975
1976 static __net_init int l2tp_init_net(struct net *net)
1977 {
1978 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1979 int hash;
1980
1981 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1982 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1983
1984 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1985 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1986
1987 spin_lock_init(&pn->l2tp_session_hlist_lock);
1988
1989 return 0;
1990 }
1991
1992 static __net_exit void l2tp_exit_net(struct net *net)
1993 {
1994 struct l2tp_net *pn = l2tp_pernet(net);
1995 struct l2tp_tunnel *tunnel = NULL;
1996
1997 rcu_read_lock_bh();
1998 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1999 (void)l2tp_tunnel_delete(tunnel);
2000 }
2001 rcu_read_unlock_bh();
2002 }
2003
2004 static struct pernet_operations l2tp_net_ops = {
2005 .init = l2tp_init_net,
2006 .exit = l2tp_exit_net,
2007 .id = &l2tp_net_id,
2008 .size = sizeof(struct l2tp_net),
2009 };
2010
2011 static int __init l2tp_init(void)
2012 {
2013 int rc = 0;
2014
2015 rc = register_pernet_device(&l2tp_net_ops);
2016 if (rc)
2017 goto out;
2018
2019 l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
2020 if (!l2tp_wq) {
2021 pr_err("alloc_workqueue failed\n");
2022 rc = -ENOMEM;
2023 goto out;
2024 }
2025
2026 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
2027
2028 out:
2029 return rc;
2030 }
2031
2032 static void __exit l2tp_exit(void)
2033 {
2034 unregister_pernet_device(&l2tp_net_ops);
2035 if (l2tp_wq) {
2036 destroy_workqueue(l2tp_wq);
2037 l2tp_wq = NULL;
2038 }
2039 }
2040
2041 module_init(l2tp_init);
2042 module_exit(l2tp_exit);
2043
2044 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
2045 MODULE_DESCRIPTION("L2TP core");
2046 MODULE_LICENSE("GPL");
2047 MODULE_VERSION(L2TP_DRV_VERSION);
2048
Linux with added FPC-III support