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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#include <linux/module.h>
22#include <linux/string.h>
23#include <linux/list.h>
24#include <linux/rculist.h>
25#include <linux/uaccess.h>
26
27#include <linux/kernel.h>
28#include <linux/spinlock.h>
29#include <linux/kthread.h>
30#include <linux/sched.h>
31#include <linux/slab.h>
32#include <linux/errno.h>
33#include <linux/jiffies.h>
34
35#include <linux/netdevice.h>
36#include <linux/net.h>
37#include <linux/inetdevice.h>
38#include <linux/skbuff.h>
39#include <linux/init.h>
40#include <linux/in.h>
41#include <linux/ip.h>
42#include <linux/udp.h>
43#include <linux/l2tp.h>
44#include <linux/hash.h>
45#include <linux/sort.h>
46#include <linux/file.h>
47#include <linux/nsproxy.h>
48#include <net/net_namespace.h>
49#include <net/netns/generic.h>
50#include <net/dst.h>
51#include <net/ip.h>
52#include <net/udp.h>
53#include <net/inet_common.h>
54#include <net/xfrm.h>
55#include <net/protocol.h>
56
57#include <asm/byteorder.h>
58#include <linux/atomic.h>
59
60#include "l2tp_core.h"
61
62#define L2TP_DRV_VERSION "V2.0"
63
64/* L2TP header constants */
65#define L2TP_HDRFLAG_T 0x8000
66#define L2TP_HDRFLAG_L 0x4000
67#define L2TP_HDRFLAG_S 0x0800
68#define L2TP_HDRFLAG_O 0x0200
69#define L2TP_HDRFLAG_P 0x0100
70
71#define L2TP_HDR_VER_MASK 0x000F
72#define L2TP_HDR_VER_2 0x0002
73#define L2TP_HDR_VER_3 0x0003
74
75/* L2TPv3 default L2-specific sublayer */
76#define L2TP_SLFLAG_S 0x40000000
77#define L2TP_SL_SEQ_MASK 0x00ffffff
78
79#define L2TP_HDR_SIZE_SEQ 10
80#define L2TP_HDR_SIZE_NOSEQ 6
81
82/* Default trace flags */
83#define L2TP_DEFAULT_DEBUG_FLAGS 0
84
85#define PRINTK(_mask, _type, _lvl, _fmt, args...) \
86 do { \
87 if ((_mask) & (_type)) \
88 printk(_lvl "L2TP: " _fmt, ##args); \
89 } while (0)
90
91/* Private data stored for received packets in the skb.
92 */
93struct 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
102static atomic_t l2tp_tunnel_count;
103static atomic_t l2tp_session_count;
104
105/* per-net private data for this module */
106static unsigned int l2tp_net_id;
107struct l2tp_net {
108 struct list_head l2tp_tunnel_list;
109 spinlock_t l2tp_tunnel_list_lock;
110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
111 spinlock_t l2tp_session_hlist_lock;
112};
113
114static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
115static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
116static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
117
118static inline struct l2tp_net *l2tp_pernet(struct net *net)
119{
120 BUG_ON(!net);
121
122 return net_generic(net, l2tp_net_id);
123}
124
125
126/* Tunnel reference counts. Incremented per session that is added to
127 * the tunnel.
128 */
129static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
130{
131 atomic_inc(&tunnel->ref_count);
132}
133
134static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
135{
136 if (atomic_dec_and_test(&tunnel->ref_count))
137 l2tp_tunnel_free(tunnel);
138}
139#ifdef L2TP_REFCNT_DEBUG
140#define l2tp_tunnel_inc_refcount(_t) do { \
141 printk(KERN_DEBUG "l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
142 l2tp_tunnel_inc_refcount_1(_t); \
143 } while (0)
144#define l2tp_tunnel_dec_refcount(_t) do { \
145 printk(KERN_DEBUG "l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
146 l2tp_tunnel_dec_refcount_1(_t); \
147 } while (0)
148#else
149#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
150#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
151#endif
152
153/* Session hash global list for L2TPv3.
154 * The session_id SHOULD be random according to RFC3931, but several
155 * L2TP implementations use incrementing session_ids. So we do a real
156 * hash on the session_id, rather than a simple bitmask.
157 */
158static inline struct hlist_head *
159l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
160{
161 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
162
163}
164
165/* Lookup a session by id in the global session list
166 */
167static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
168{
169 struct l2tp_net *pn = l2tp_pernet(net);
170 struct hlist_head *session_list =
171 l2tp_session_id_hash_2(pn, session_id);
172 struct l2tp_session *session;
173 struct hlist_node *walk;
174
175 rcu_read_lock_bh();
176 hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
177 if (session->session_id == session_id) {
178 rcu_read_unlock_bh();
179 return session;
180 }
181 }
182 rcu_read_unlock_bh();
183
184 return NULL;
185}
186
187/* Session hash list.
188 * The session_id SHOULD be random according to RFC2661, but several
189 * L2TP implementations (Cisco and Microsoft) use incrementing
190 * session_ids. So we do a real hash on the session_id, rather than a
191 * simple bitmask.
192 */
193static inline struct hlist_head *
194l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
195{
196 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
197}
198
199/* Lookup a session by id
200 */
201struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
202{
203 struct hlist_head *session_list;
204 struct l2tp_session *session;
205 struct hlist_node *walk;
206
207 /* In L2TPv3, session_ids are unique over all tunnels and we
208 * sometimes need to look them up before we know the
209 * tunnel.
210 */
211 if (tunnel == NULL)
212 return l2tp_session_find_2(net, session_id);
213
214 session_list = l2tp_session_id_hash(tunnel, session_id);
215 read_lock_bh(&tunnel->hlist_lock);
216 hlist_for_each_entry(session, walk, session_list, hlist) {
217 if (session->session_id == session_id) {
218 read_unlock_bh(&tunnel->hlist_lock);
219 return session;
220 }
221 }
222 read_unlock_bh(&tunnel->hlist_lock);
223
224 return NULL;
225}
226EXPORT_SYMBOL_GPL(l2tp_session_find);
227
228struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
229{
230 int hash;
231 struct hlist_node *walk;
232 struct l2tp_session *session;
233 int count = 0;
234
235 read_lock_bh(&tunnel->hlist_lock);
236 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
237 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
238 if (++count > nth) {
239 read_unlock_bh(&tunnel->hlist_lock);
240 return session;
241 }
242 }
243 }
244
245 read_unlock_bh(&tunnel->hlist_lock);
246
247 return NULL;
248}
249EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
250
251/* Lookup a session by interface name.
252 * This is very inefficient but is only used by management interfaces.
253 */
254struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
255{
256 struct l2tp_net *pn = l2tp_pernet(net);
257 int hash;
258 struct hlist_node *walk;
259 struct l2tp_session *session;
260
261 rcu_read_lock_bh();
262 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
263 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
264 if (!strcmp(session->ifname, ifname)) {
265 rcu_read_unlock_bh();
266 return session;
267 }
268 }
269 }
270
271 rcu_read_unlock_bh();
272
273 return NULL;
274}
275EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
276
277/* Lookup a tunnel by id
278 */
279struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
280{
281 struct l2tp_tunnel *tunnel;
282 struct l2tp_net *pn = l2tp_pernet(net);
283
284 rcu_read_lock_bh();
285 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
286 if (tunnel->tunnel_id == tunnel_id) {
287 rcu_read_unlock_bh();
288 return tunnel;
289 }
290 }
291 rcu_read_unlock_bh();
292
293 return NULL;
294}
295EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
296
297struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
298{
299 struct l2tp_net *pn = l2tp_pernet(net);
300 struct l2tp_tunnel *tunnel;
301 int count = 0;
302
303 rcu_read_lock_bh();
304 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
305 if (++count > nth) {
306 rcu_read_unlock_bh();
307 return tunnel;
308 }
309 }
310
311 rcu_read_unlock_bh();
312
313 return NULL;
314}
315EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
316
317/*****************************************************************************
318 * Receive data handling
319 *****************************************************************************/
320
321/* Queue a skb in order. We come here only if the skb has an L2TP sequence
322 * number.
323 */
324static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
325{
326 struct sk_buff *skbp;
327 struct sk_buff *tmp;
328 u32 ns = L2TP_SKB_CB(skb)->ns;
329
330 spin_lock_bh(&session->reorder_q.lock);
331 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
332 if (L2TP_SKB_CB(skbp)->ns > ns) {
333 __skb_queue_before(&session->reorder_q, skbp, skb);
334 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
335 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
336 session->name, ns, L2TP_SKB_CB(skbp)->ns,
337 skb_queue_len(&session->reorder_q));
338 session->stats.rx_oos_packets++;
339 goto out;
340 }
341 }
342
343 __skb_queue_tail(&session->reorder_q, skb);
344
345out:
346 spin_unlock_bh(&session->reorder_q.lock);
347}
348
349/* Dequeue a single skb.
350 */
351static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
352{
353 struct l2tp_tunnel *tunnel = session->tunnel;
354 int length = L2TP_SKB_CB(skb)->length;
355
356 /* We're about to requeue the skb, so return resources
357 * to its current owner (a socket receive buffer).
358 */
359 skb_orphan(skb);
360
361 tunnel->stats.rx_packets++;
362 tunnel->stats.rx_bytes += length;
363 session->stats.rx_packets++;
364 session->stats.rx_bytes += length;
365
366 if (L2TP_SKB_CB(skb)->has_seq) {
367 /* Bump our Nr */
368 session->nr++;
369 if (tunnel->version == L2TP_HDR_VER_2)
370 session->nr &= 0xffff;
371 else
372 session->nr &= 0xffffff;
373
374 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
375 "%s: updated nr to %hu\n", session->name, session->nr);
376 }
377
378 /* call private receive handler */
379 if (session->recv_skb != NULL)
380 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
381 else
382 kfree_skb(skb);
383
384 if (session->deref)
385 (*session->deref)(session);
386}
387
388/* Dequeue skbs from the session's reorder_q, subject to packet order.
389 * Skbs that have been in the queue for too long are simply discarded.
390 */
391static void l2tp_recv_dequeue(struct l2tp_session *session)
392{
393 struct sk_buff *skb;
394 struct sk_buff *tmp;
395
396 /* If the pkt at the head of the queue has the nr that we
397 * expect to send up next, dequeue it and any other
398 * in-sequence packets behind it.
399 */
400 spin_lock_bh(&session->reorder_q.lock);
401 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
402 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
403 session->stats.rx_seq_discards++;
404 session->stats.rx_errors++;
405 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
406 "%s: oos pkt %u len %d discarded (too old), "
407 "waiting for %u, reorder_q_len=%d\n",
408 session->name, L2TP_SKB_CB(skb)->ns,
409 L2TP_SKB_CB(skb)->length, session->nr,
410 skb_queue_len(&session->reorder_q));
411 __skb_unlink(skb, &session->reorder_q);
412 kfree_skb(skb);
413 if (session->deref)
414 (*session->deref)(session);
415 continue;
416 }
417
418 if (L2TP_SKB_CB(skb)->has_seq) {
419 if (L2TP_SKB_CB(skb)->ns != session->nr) {
420 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
421 "%s: holding oos pkt %u len %d, "
422 "waiting for %u, reorder_q_len=%d\n",
423 session->name, L2TP_SKB_CB(skb)->ns,
424 L2TP_SKB_CB(skb)->length, session->nr,
425 skb_queue_len(&session->reorder_q));
426 goto out;
427 }
428 }
429 __skb_unlink(skb, &session->reorder_q);
430
431 /* Process the skb. We release the queue lock while we
432 * do so to let other contexts process the queue.
433 */
434 spin_unlock_bh(&session->reorder_q.lock);
435 l2tp_recv_dequeue_skb(session, skb);
436 spin_lock_bh(&session->reorder_q.lock);
437 }
438
439out:
440 spin_unlock_bh(&session->reorder_q.lock);
441}
442
443static inline int l2tp_verify_udp_checksum(struct sock *sk,
444 struct sk_buff *skb)
445{
446 struct udphdr *uh = udp_hdr(skb);
447 u16 ulen = ntohs(uh->len);
448 struct inet_sock *inet;
449 __wsum psum;
450
451 if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
452 return 0;
453
454 inet = inet_sk(sk);
455 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
456 IPPROTO_UDP, 0);
457
458 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
459 !csum_fold(csum_add(psum, skb->csum)))
460 return 0;
461
462 skb->csum = psum;
463
464 return __skb_checksum_complete(skb);
465}
466
467/* Do receive processing of L2TP data frames. We handle both L2TPv2
468 * and L2TPv3 data frames here.
469 *
470 * L2TPv2 Data Message Header
471 *
472 * 0 1 2 3
473 * 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
474 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
475 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
476 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
477 * | Tunnel ID | Session ID |
478 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
479 * | Ns (opt) | Nr (opt) |
480 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
481 * | Offset Size (opt) | Offset pad... (opt)
482 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
483 *
484 * Data frames are marked by T=0. All other fields are the same as
485 * those in L2TP control frames.
486 *
487 * L2TPv3 Data Message Header
488 *
489 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
490 * | L2TP Session Header |
491 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
492 * | L2-Specific Sublayer |
493 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
494 * | Tunnel Payload ...
495 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
496 *
497 * L2TPv3 Session Header Over IP
498 *
499 * 0 1 2 3
500 * 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
501 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
502 * | Session ID |
503 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
504 * | Cookie (optional, maximum 64 bits)...
505 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
506 * |
507 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
508 *
509 * L2TPv3 L2-Specific Sublayer Format
510 *
511 * 0 1 2 3
512 * 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
513 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
514 * |x|S|x|x|x|x|x|x| Sequence Number |
515 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
516 *
517 * Cookie value, sublayer format and offset (pad) are negotiated with
518 * the peer when the session is set up. Unlike L2TPv2, we do not need
519 * to parse the packet header to determine if optional fields are
520 * present.
521 *
522 * Caller must already have parsed the frame and determined that it is
523 * a data (not control) frame before coming here. Fields up to the
524 * session-id have already been parsed and ptr points to the data
525 * after the session-id.
526 */
527void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
528 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
529 int length, int (*payload_hook)(struct sk_buff *skb))
530{
531 struct l2tp_tunnel *tunnel = session->tunnel;
532 int offset;
533 u32 ns, nr;
534
535 /* The ref count is increased since we now hold a pointer to
536 * the session. Take care to decrement the refcnt when exiting
537 * this function from now on...
538 */
539 l2tp_session_inc_refcount(session);
540 if (session->ref)
541 (*session->ref)(session);
542
543 /* Parse and check optional cookie */
544 if (session->peer_cookie_len > 0) {
545 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
546 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
547 "%s: cookie mismatch (%u/%u). Discarding.\n",
548 tunnel->name, tunnel->tunnel_id, session->session_id);
549 session->stats.rx_cookie_discards++;
550 goto discard;
551 }
552 ptr += session->peer_cookie_len;
553 }
554
555 /* Handle the optional sequence numbers. Sequence numbers are
556 * in different places for L2TPv2 and L2TPv3.
557 *
558 * If we are the LAC, enable/disable sequence numbers under
559 * the control of the LNS. If no sequence numbers present but
560 * we were expecting them, discard frame.
561 */
562 ns = nr = 0;
563 L2TP_SKB_CB(skb)->has_seq = 0;
564 if (tunnel->version == L2TP_HDR_VER_2) {
565 if (hdrflags & L2TP_HDRFLAG_S) {
566 ns = ntohs(*(__be16 *) ptr);
567 ptr += 2;
568 nr = ntohs(*(__be16 *) ptr);
569 ptr += 2;
570
571 /* Store L2TP info in the skb */
572 L2TP_SKB_CB(skb)->ns = ns;
573 L2TP_SKB_CB(skb)->has_seq = 1;
574
575 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
576 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
577 session->name, ns, nr, session->nr);
578 }
579 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
580 u32 l2h = ntohl(*(__be32 *) ptr);
581
582 if (l2h & 0x40000000) {
583 ns = l2h & 0x00ffffff;
584
585 /* Store L2TP info in the skb */
586 L2TP_SKB_CB(skb)->ns = ns;
587 L2TP_SKB_CB(skb)->has_seq = 1;
588
589 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
590 "%s: recv data ns=%u, session nr=%u\n",
591 session->name, ns, session->nr);
592 }
593 }
594
595 /* Advance past L2-specific header, if present */
596 ptr += session->l2specific_len;
597
598 if (L2TP_SKB_CB(skb)->has_seq) {
599 /* Received a packet with sequence numbers. If we're the LNS,
600 * check if we sre sending sequence numbers and if not,
601 * configure it so.
602 */
603 if ((!session->lns_mode) && (!session->send_seq)) {
604 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
605 "%s: requested to enable seq numbers by LNS\n",
606 session->name);
607 session->send_seq = -1;
608 l2tp_session_set_header_len(session, tunnel->version);
609 }
610 } else {
611 /* No sequence numbers.
612 * If user has configured mandatory sequence numbers, discard.
613 */
614 if (session->recv_seq) {
615 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
616 "%s: recv data has no seq numbers when required. "
617 "Discarding\n", session->name);
618 session->stats.rx_seq_discards++;
619 goto discard;
620 }
621
622 /* If we're the LAC and we're sending sequence numbers, the
623 * LNS has requested that we no longer send sequence numbers.
624 * If we're the LNS and we're sending sequence numbers, the
625 * LAC is broken. Discard the frame.
626 */
627 if ((!session->lns_mode) && (session->send_seq)) {
628 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
629 "%s: requested to disable seq numbers by LNS\n",
630 session->name);
631 session->send_seq = 0;
632 l2tp_session_set_header_len(session, tunnel->version);
633 } else if (session->send_seq) {
634 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
635 "%s: recv data has no seq numbers when required. "
636 "Discarding\n", session->name);
637 session->stats.rx_seq_discards++;
638 goto discard;
639 }
640 }
641
642 /* Session data offset is handled differently for L2TPv2 and
643 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
644 * the header. For L2TPv3, the offset is negotiated using AVPs
645 * in the session setup control protocol.
646 */
647 if (tunnel->version == L2TP_HDR_VER_2) {
648 /* If offset bit set, skip it. */
649 if (hdrflags & L2TP_HDRFLAG_O) {
650 offset = ntohs(*(__be16 *)ptr);
651 ptr += 2 + offset;
652 }
653 } else
654 ptr += session->offset;
655
656 offset = ptr - optr;
657 if (!pskb_may_pull(skb, offset))
658 goto discard;
659
660 __skb_pull(skb, offset);
661
662 /* If caller wants to process the payload before we queue the
663 * packet, do so now.
664 */
665 if (payload_hook)
666 if ((*payload_hook)(skb))
667 goto discard;
668
669 /* Prepare skb for adding to the session's reorder_q. Hold
670 * packets for max reorder_timeout or 1 second if not
671 * reordering.
672 */
673 L2TP_SKB_CB(skb)->length = length;
674 L2TP_SKB_CB(skb)->expires = jiffies +
675 (session->reorder_timeout ? session->reorder_timeout : HZ);
676
677 /* Add packet to the session's receive queue. Reordering is done here, if
678 * enabled. Saved L2TP protocol info is stored in skb->sb[].
679 */
680 if (L2TP_SKB_CB(skb)->has_seq) {
681 if (session->reorder_timeout != 0) {
682 /* Packet reordering enabled. Add skb to session's
683 * reorder queue, in order of ns.
684 */
685 l2tp_recv_queue_skb(session, skb);
686 } else {
687 /* Packet reordering disabled. Discard out-of-sequence
688 * packets
689 */
690 if (L2TP_SKB_CB(skb)->ns != session->nr) {
691 session->stats.rx_seq_discards++;
692 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
693 "%s: oos pkt %u len %d discarded, "
694 "waiting for %u, reorder_q_len=%d\n",
695 session->name, L2TP_SKB_CB(skb)->ns,
696 L2TP_SKB_CB(skb)->length, session->nr,
697 skb_queue_len(&session->reorder_q));
698 goto discard;
699 }
700 skb_queue_tail(&session->reorder_q, skb);
701 }
702 } else {
703 /* No sequence numbers. Add the skb to the tail of the
704 * reorder queue. This ensures that it will be
705 * delivered after all previous sequenced skbs.
706 */
707 skb_queue_tail(&session->reorder_q, skb);
708 }
709
710 /* Try to dequeue as many skbs from reorder_q as we can. */
711 l2tp_recv_dequeue(session);
712
713 l2tp_session_dec_refcount(session);
714
715 return;
716
717discard:
718 session->stats.rx_errors++;
719 kfree_skb(skb);
720
721 if (session->deref)
722 (*session->deref)(session);
723
724 l2tp_session_dec_refcount(session);
725}
726EXPORT_SYMBOL(l2tp_recv_common);
727
728/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
729 * here. The skb is not on a list when we get here.
730 * Returns 0 if the packet was a data packet and was successfully passed on.
731 * Returns 1 if the packet was not a good data packet and could not be
732 * forwarded. All such packets are passed up to userspace to deal with.
733 */
734static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
735 int (*payload_hook)(struct sk_buff *skb))
736{
737 struct l2tp_session *session = NULL;
738 unsigned char *ptr, *optr;
739 u16 hdrflags;
740 u32 tunnel_id, session_id;
741 int offset;
742 u16 version;
743 int length;
744
745 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
746 goto discard_bad_csum;
747
748 /* UDP always verifies the packet length. */
749 __skb_pull(skb, sizeof(struct udphdr));
750
751 /* Short packet? */
752 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
753 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
754 "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
755 goto error;
756 }
757
758 /* Point to L2TP header */
759 optr = ptr = skb->data;
760
761 /* Trace packet contents, if enabled */
762 if (tunnel->debug & L2TP_MSG_DATA) {
763 length = min(32u, skb->len);
764 if (!pskb_may_pull(skb, length))
765 goto error;
766
767 printk(KERN_DEBUG "%s: recv: ", tunnel->name);
768
769 offset = 0;
770 do {
771 printk(" %02X", ptr[offset]);
772 } while (++offset < length);
773
774 printk("\n");
775 }
776
777 /* Get L2TP header flags */
778 hdrflags = ntohs(*(__be16 *) ptr);
779
780 /* Check protocol version */
781 version = hdrflags & L2TP_HDR_VER_MASK;
782 if (version != tunnel->version) {
783 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
784 "%s: recv protocol version mismatch: got %d expected %d\n",
785 tunnel->name, version, tunnel->version);
786 goto error;
787 }
788
789 /* Get length of L2TP packet */
790 length = skb->len;
791
792 /* If type is control packet, it is handled by userspace. */
793 if (hdrflags & L2TP_HDRFLAG_T) {
794 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
795 "%s: recv control packet, len=%d\n", tunnel->name, length);
796 goto error;
797 }
798
799 /* Skip flags */
800 ptr += 2;
801
802 if (tunnel->version == L2TP_HDR_VER_2) {
803 /* If length is present, skip it */
804 if (hdrflags & L2TP_HDRFLAG_L)
805 ptr += 2;
806
807 /* Extract tunnel and session ID */
808 tunnel_id = ntohs(*(__be16 *) ptr);
809 ptr += 2;
810 session_id = ntohs(*(__be16 *) ptr);
811 ptr += 2;
812 } else {
813 ptr += 2; /* skip reserved bits */
814 tunnel_id = tunnel->tunnel_id;
815 session_id = ntohl(*(__be32 *) ptr);
816 ptr += 4;
817 }
818
819 /* Find the session context */
820 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
821 if (!session || !session->recv_skb) {
822 /* Not found? Pass to userspace to deal with */
823 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
824 "%s: no session found (%u/%u). Passing up.\n",
825 tunnel->name, tunnel_id, session_id);
826 goto error;
827 }
828
829 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
830
831 return 0;
832
833discard_bad_csum:
834 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
835 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
836 tunnel->stats.rx_errors++;
837 kfree_skb(skb);
838
839 return 0;
840
841error:
842 /* Put UDP header back */
843 __skb_push(skb, sizeof(struct udphdr));
844
845 return 1;
846}
847
848/* UDP encapsulation receive handler. See net/ipv4/udp.c.
849 * Return codes:
850 * 0 : success.
851 * <0: error
852 * >0: skb should be passed up to userspace as UDP.
853 */
854int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
855{
856 struct l2tp_tunnel *tunnel;
857
858 tunnel = l2tp_sock_to_tunnel(sk);
859 if (tunnel == NULL)
860 goto pass_up;
861
862 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
863 "%s: received %d bytes\n", tunnel->name, skb->len);
864
865 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
866 goto pass_up_put;
867
868 sock_put(sk);
869 return 0;
870
871pass_up_put:
872 sock_put(sk);
873pass_up:
874 return 1;
875}
876EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
877
878/************************************************************************
879 * Transmit handling
880 ***********************************************************************/
881
882/* Build an L2TP header for the session into the buffer provided.
883 */
884static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
885{
886 struct l2tp_tunnel *tunnel = session->tunnel;
887 __be16 *bufp = buf;
888 __be16 *optr = buf;
889 u16 flags = L2TP_HDR_VER_2;
890 u32 tunnel_id = tunnel->peer_tunnel_id;
891 u32 session_id = session->peer_session_id;
892
893 if (session->send_seq)
894 flags |= L2TP_HDRFLAG_S;
895
896 /* Setup L2TP header. */
897 *bufp++ = htons(flags);
898 *bufp++ = htons(tunnel_id);
899 *bufp++ = htons(session_id);
900 if (session->send_seq) {
901 *bufp++ = htons(session->ns);
902 *bufp++ = 0;
903 session->ns++;
904 session->ns &= 0xffff;
905 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
906 "%s: updated ns to %u\n", session->name, session->ns);
907 }
908
909 return bufp - optr;
910}
911
912static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
913{
914 struct l2tp_tunnel *tunnel = session->tunnel;
915 char *bufp = buf;
916 char *optr = bufp;
917
918 /* Setup L2TP header. The header differs slightly for UDP and
919 * IP encapsulations. For UDP, there is 4 bytes of flags.
920 */
921 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
922 u16 flags = L2TP_HDR_VER_3;
923 *((__be16 *) bufp) = htons(flags);
924 bufp += 2;
925 *((__be16 *) bufp) = 0;
926 bufp += 2;
927 }
928
929 *((__be32 *) bufp) = htonl(session->peer_session_id);
930 bufp += 4;
931 if (session->cookie_len) {
932 memcpy(bufp, &session->cookie[0], session->cookie_len);
933 bufp += session->cookie_len;
934 }
935 if (session->l2specific_len) {
936 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
937 u32 l2h = 0;
938 if (session->send_seq) {
939 l2h = 0x40000000 | session->ns;
940 session->ns++;
941 session->ns &= 0xffffff;
942 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
943 "%s: updated ns to %u\n", session->name, session->ns);
944 }
945
946 *((__be32 *) bufp) = htonl(l2h);
947 }
948 bufp += session->l2specific_len;
949 }
950 if (session->offset)
951 bufp += session->offset;
952
953 return bufp - optr;
954}
955
956static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
957 struct flowi *fl, size_t data_len)
958{
959 struct l2tp_tunnel *tunnel = session->tunnel;
960 unsigned int len = skb->len;
961 int error;
962
963 /* Debug */
964 if (session->send_seq)
965 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
966 "%s: send %Zd bytes, ns=%u\n", session->name,
967 data_len, session->ns - 1);
968 else
969 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
970 "%s: send %Zd bytes\n", session->name, data_len);
971
972 if (session->debug & L2TP_MSG_DATA) {
973 int i;
974 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
975 unsigned char *datap = skb->data + uhlen;
976
977 printk(KERN_DEBUG "%s: xmit:", session->name);
978 for (i = 0; i < (len - uhlen); i++) {
979 printk(" %02X", *datap++);
980 if (i == 31) {
981 printk(" ...");
982 break;
983 }
984 }
985 printk("\n");
986 }
987
988 /* Queue the packet to IP for output */
989 skb->local_df = 1;
990 error = ip_queue_xmit(skb, fl);
991
992 /* Update stats */
993 if (error >= 0) {
994 tunnel->stats.tx_packets++;
995 tunnel->stats.tx_bytes += len;
996 session->stats.tx_packets++;
997 session->stats.tx_bytes += len;
998 } else {
999 tunnel->stats.tx_errors++;
1000 session->stats.tx_errors++;
1001 }
1002
1003 return 0;
1004}
1005
1006/* Automatically called when the skb is freed.
1007 */
1008static void l2tp_sock_wfree(struct sk_buff *skb)
1009{
1010 sock_put(skb->sk);
1011}
1012
1013/* For data skbs that we transmit, we associate with the tunnel socket
1014 * but don't do accounting.
1015 */
1016static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1017{
1018 sock_hold(sk);
1019 skb->sk = sk;
1020 skb->destructor = l2tp_sock_wfree;
1021}
1022
1023/* If caller requires the skb to have a ppp header, the header must be
1024 * inserted in the skb data before calling this function.
1025 */
1026int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1027{
1028 int data_len = skb->len;
1029 struct l2tp_tunnel *tunnel = session->tunnel;
1030 struct sock *sk = tunnel->sock;
1031 struct flowi *fl;
1032 struct udphdr *uh;
1033 struct inet_sock *inet;
1034 __wsum csum;
1035 int old_headroom;
1036 int new_headroom;
1037 int headroom;
1038 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1039 int udp_len;
1040
1041 /* Check that there's enough headroom in the skb to insert IP,
1042 * UDP and L2TP headers. If not enough, expand it to
1043 * make room. Adjust truesize.
1044 */
1045 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1046 uhlen + hdr_len;
1047 old_headroom = skb_headroom(skb);
1048 if (skb_cow_head(skb, headroom)) {
1049 dev_kfree_skb(skb);
1050 goto abort;
1051 }
1052
1053 new_headroom = skb_headroom(skb);
1054 skb_orphan(skb);
1055 skb->truesize += new_headroom - old_headroom;
1056
1057 /* Setup L2TP header */
1058 session->build_header(session, __skb_push(skb, hdr_len));
1059
1060 /* Reset skb netfilter state */
1061 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1062 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1063 IPSKB_REROUTED);
1064 nf_reset(skb);
1065
1066 bh_lock_sock(sk);
1067 if (sock_owned_by_user(sk)) {
1068 dev_kfree_skb(skb);
1069 goto out_unlock;
1070 }
1071
1072 /* Get routing info from the tunnel socket */
1073 skb_dst_drop(skb);
1074 skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
1075
1076 inet = inet_sk(sk);
1077 fl = &inet->cork.fl;
1078 switch (tunnel->encap) {
1079 case L2TP_ENCAPTYPE_UDP:
1080 /* Setup UDP header */
1081 __skb_push(skb, sizeof(*uh));
1082 skb_reset_transport_header(skb);
1083 uh = udp_hdr(skb);
1084 uh->source = inet->inet_sport;
1085 uh->dest = inet->inet_dport;
1086 udp_len = uhlen + hdr_len + data_len;
1087 uh->len = htons(udp_len);
1088 uh->check = 0;
1089
1090 /* Calculate UDP checksum if configured to do so */
1091 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1092 skb->ip_summed = CHECKSUM_NONE;
1093 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1094 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1095 skb->ip_summed = CHECKSUM_COMPLETE;
1096 csum = skb_checksum(skb, 0, udp_len, 0);
1097 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1098 inet->inet_daddr,
1099 udp_len, IPPROTO_UDP, csum);
1100 if (uh->check == 0)
1101 uh->check = CSUM_MANGLED_0;
1102 } else {
1103 skb->ip_summed = CHECKSUM_PARTIAL;
1104 skb->csum_start = skb_transport_header(skb) - skb->head;
1105 skb->csum_offset = offsetof(struct udphdr, check);
1106 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1107 inet->inet_daddr,
1108 udp_len, IPPROTO_UDP, 0);
1109 }
1110 break;
1111
1112 case L2TP_ENCAPTYPE_IP:
1113 break;
1114 }
1115
1116 l2tp_skb_set_owner_w(skb, sk);
1117
1118 l2tp_xmit_core(session, skb, fl, data_len);
1119out_unlock:
1120 bh_unlock_sock(sk);
1121
1122abort:
1123 return 0;
1124}
1125EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1126
1127/*****************************************************************************
1128 * Tinnel and session create/destroy.
1129 *****************************************************************************/
1130
1131/* Tunnel socket destruct hook.
1132 * The tunnel context is deleted only when all session sockets have been
1133 * closed.
1134 */
1135static void l2tp_tunnel_destruct(struct sock *sk)
1136{
1137 struct l2tp_tunnel *tunnel;
1138
1139 tunnel = sk->sk_user_data;
1140 if (tunnel == NULL)
1141 goto end;
1142
1143 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1144 "%s: closing...\n", tunnel->name);
1145
1146 /* Close all sessions */
1147 l2tp_tunnel_closeall(tunnel);
1148
1149 switch (tunnel->encap) {
1150 case L2TP_ENCAPTYPE_UDP:
1151 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1152 (udp_sk(sk))->encap_type = 0;
1153 (udp_sk(sk))->encap_rcv = NULL;
1154 break;
1155 case L2TP_ENCAPTYPE_IP:
1156 break;
1157 }
1158
1159 /* Remove hooks into tunnel socket */
1160 tunnel->sock = NULL;
1161 sk->sk_destruct = tunnel->old_sk_destruct;
1162 sk->sk_user_data = NULL;
1163
1164 /* Call the original destructor */
1165 if (sk->sk_destruct)
1166 (*sk->sk_destruct)(sk);
1167
1168 /* We're finished with the socket */
1169 l2tp_tunnel_dec_refcount(tunnel);
1170
1171end:
1172 return;
1173}
1174
1175/* When the tunnel is closed, all the attached sessions need to go too.
1176 */
1177static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1178{
1179 int hash;
1180 struct hlist_node *walk;
1181 struct hlist_node *tmp;
1182 struct l2tp_session *session;
1183
1184 BUG_ON(tunnel == NULL);
1185
1186 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1187 "%s: closing all sessions...\n", tunnel->name);
1188
1189 write_lock_bh(&tunnel->hlist_lock);
1190 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1191again:
1192 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1193 session = hlist_entry(walk, struct l2tp_session, hlist);
1194
1195 PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
1196 "%s: closing session\n", session->name);
1197
1198 hlist_del_init(&session->hlist);
1199
1200 /* Since we should hold the sock lock while
1201 * doing any unbinding, we need to release the
1202 * lock we're holding before taking that lock.
1203 * Hold a reference to the sock so it doesn't
1204 * disappear as we're jumping between locks.
1205 */
1206 if (session->ref != NULL)
1207 (*session->ref)(session);
1208
1209 write_unlock_bh(&tunnel->hlist_lock);
1210
1211 if (tunnel->version != L2TP_HDR_VER_2) {
1212 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1213
1214 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1215 hlist_del_init_rcu(&session->global_hlist);
1216 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1217 synchronize_rcu();
1218 }
1219
1220 if (session->session_close != NULL)
1221 (*session->session_close)(session);
1222
1223 if (session->deref != NULL)
1224 (*session->deref)(session);
1225
1226 write_lock_bh(&tunnel->hlist_lock);
1227
1228 /* Now restart from the beginning of this hash
1229 * chain. We always remove a session from the
1230 * list so we are guaranteed to make forward
1231 * progress.
1232 */
1233 goto again;
1234 }
1235 }
1236 write_unlock_bh(&tunnel->hlist_lock);
1237}
1238
1239/* Really kill the tunnel.
1240 * Come here only when all sessions have been cleared from the tunnel.
1241 */
1242static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1243{
1244 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1245
1246 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1247 BUG_ON(tunnel->sock != NULL);
1248
1249 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1250 "%s: free...\n", tunnel->name);
1251
1252 /* Remove from tunnel list */
1253 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1254 list_del_rcu(&tunnel->list);
1255 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1256 synchronize_rcu();
1257
1258 atomic_dec(&l2tp_tunnel_count);
1259 kfree(tunnel);
1260}
1261
1262/* Create a socket for the tunnel, if one isn't set up by
1263 * userspace. This is used for static tunnels where there is no
1264 * managing L2TP daemon.
1265 */
1266static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1267{
1268 int err = -EINVAL;
1269 struct sockaddr_in udp_addr;
1270 struct sockaddr_l2tpip ip_addr;
1271 struct socket *sock = NULL;
1272
1273 switch (cfg->encap) {
1274 case L2TP_ENCAPTYPE_UDP:
1275 err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1276 if (err < 0)
1277 goto out;
1278
1279 sock = *sockp;
1280
1281 memset(&udp_addr, 0, sizeof(udp_addr));
1282 udp_addr.sin_family = AF_INET;
1283 udp_addr.sin_addr = cfg->local_ip;
1284 udp_addr.sin_port = htons(cfg->local_udp_port);
1285 err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr));
1286 if (err < 0)
1287 goto out;
1288
1289 udp_addr.sin_family = AF_INET;
1290 udp_addr.sin_addr = cfg->peer_ip;
1291 udp_addr.sin_port = htons(cfg->peer_udp_port);
1292 err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0);
1293 if (err < 0)
1294 goto out;
1295
1296 if (!cfg->use_udp_checksums)
1297 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1298
1299 break;
1300
1301 case L2TP_ENCAPTYPE_IP:
1302 err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP, sockp);
1303 if (err < 0)
1304 goto out;
1305
1306 sock = *sockp;
1307
1308 memset(&ip_addr, 0, sizeof(ip_addr));
1309 ip_addr.l2tp_family = AF_INET;
1310 ip_addr.l2tp_addr = cfg->local_ip;
1311 ip_addr.l2tp_conn_id = tunnel_id;
1312 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr));
1313 if (err < 0)
1314 goto out;
1315
1316 ip_addr.l2tp_family = AF_INET;
1317 ip_addr.l2tp_addr = cfg->peer_ip;
1318 ip_addr.l2tp_conn_id = peer_tunnel_id;
1319 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr), 0);
1320 if (err < 0)
1321 goto out;
1322
1323 break;
1324
1325 default:
1326 goto out;
1327 }
1328
1329out:
1330 if ((err < 0) && sock) {
1331 sock_release(sock);
1332 *sockp = NULL;
1333 }
1334
1335 return err;
1336}
1337
1338int 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)
1339{
1340 struct l2tp_tunnel *tunnel = NULL;
1341 int err;
1342 struct socket *sock = NULL;
1343 struct sock *sk = NULL;
1344 struct l2tp_net *pn;
1345 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1346
1347 /* Get the tunnel socket from the fd, which was opened by
1348 * the userspace L2TP daemon. If not specified, create a
1349 * kernel socket.
1350 */
1351 if (fd < 0) {
1352 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1353 if (err < 0)
1354 goto err;
1355 } else {
1356 err = -EBADF;
1357 sock = sockfd_lookup(fd, &err);
1358 if (!sock) {
1359 printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1360 tunnel_id, fd, err);
1361 goto err;
1362 }
1363 }
1364
1365 sk = sock->sk;
1366
1367 if (cfg != NULL)
1368 encap = cfg->encap;
1369
1370 /* Quick sanity checks */
1371 switch (encap) {
1372 case L2TP_ENCAPTYPE_UDP:
1373 err = -EPROTONOSUPPORT;
1374 if (sk->sk_protocol != IPPROTO_UDP) {
1375 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1376 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1377 goto err;
1378 }
1379 break;
1380 case L2TP_ENCAPTYPE_IP:
1381 err = -EPROTONOSUPPORT;
1382 if (sk->sk_protocol != IPPROTO_L2TP) {
1383 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1384 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1385 goto err;
1386 }
1387 break;
1388 }
1389
1390 /* Check if this socket has already been prepped */
1391 tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1392 if (tunnel != NULL) {
1393 /* This socket has already been prepped */
1394 err = -EBUSY;
1395 goto err;
1396 }
1397
1398 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1399 if (tunnel == NULL) {
1400 err = -ENOMEM;
1401 goto err;
1402 }
1403
1404 tunnel->version = version;
1405 tunnel->tunnel_id = tunnel_id;
1406 tunnel->peer_tunnel_id = peer_tunnel_id;
1407 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1408
1409 tunnel->magic = L2TP_TUNNEL_MAGIC;
1410 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1411 rwlock_init(&tunnel->hlist_lock);
1412
1413 /* The net we belong to */
1414 tunnel->l2tp_net = net;
1415 pn = l2tp_pernet(net);
1416
1417 if (cfg != NULL)
1418 tunnel->debug = cfg->debug;
1419
1420 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1421 tunnel->encap = encap;
1422 if (encap == L2TP_ENCAPTYPE_UDP) {
1423 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1424 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1425 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1426 }
1427
1428 sk->sk_user_data = tunnel;
1429
1430 /* Hook on the tunnel socket destructor so that we can cleanup
1431 * if the tunnel socket goes away.
1432 */
1433 tunnel->old_sk_destruct = sk->sk_destruct;
1434 sk->sk_destruct = &l2tp_tunnel_destruct;
1435 tunnel->sock = sk;
1436 sk->sk_allocation = GFP_ATOMIC;
1437
1438 /* Add tunnel to our list */
1439 INIT_LIST_HEAD(&tunnel->list);
1440 atomic_inc(&l2tp_tunnel_count);
1441
1442 /* Bump the reference count. The tunnel context is deleted
1443 * only when this drops to zero. Must be done before list insertion
1444 */
1445 l2tp_tunnel_inc_refcount(tunnel);
1446 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1447 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1448 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1449
1450 err = 0;
1451err:
1452 if (tunnelp)
1453 *tunnelp = tunnel;
1454
1455 /* If tunnel's socket was created by the kernel, it doesn't
1456 * have a file.
1457 */
1458 if (sock && sock->file)
1459 sockfd_put(sock);
1460
1461 return err;
1462}
1463EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1464
1465/* This function is used by the netlink TUNNEL_DELETE command.
1466 */
1467int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1468{
1469 int err = 0;
1470 struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
1471
1472 /* Force the tunnel socket to close. This will eventually
1473 * cause the tunnel to be deleted via the normal socket close
1474 * mechanisms when userspace closes the tunnel socket.
1475 */
1476 if (sock != NULL) {
1477 err = inet_shutdown(sock, 2);
1478
1479 /* If the tunnel's socket was created by the kernel,
1480 * close the socket here since the socket was not
1481 * created by userspace.
1482 */
1483 if (sock->file == NULL)
1484 err = inet_release(sock);
1485 }
1486
1487 return err;
1488}
1489EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1490
1491/* Really kill the session.
1492 */
1493void l2tp_session_free(struct l2tp_session *session)
1494{
1495 struct l2tp_tunnel *tunnel;
1496
1497 BUG_ON(atomic_read(&session->ref_count) != 0);
1498
1499 tunnel = session->tunnel;
1500 if (tunnel != NULL) {
1501 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1502
1503 /* Delete the session from the hash */
1504 write_lock_bh(&tunnel->hlist_lock);
1505 hlist_del_init(&session->hlist);
1506 write_unlock_bh(&tunnel->hlist_lock);
1507
1508 /* Unlink from the global hash if not L2TPv2 */
1509 if (tunnel->version != L2TP_HDR_VER_2) {
1510 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1511
1512 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1513 hlist_del_init_rcu(&session->global_hlist);
1514 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1515 synchronize_rcu();
1516 }
1517
1518 if (session->session_id != 0)
1519 atomic_dec(&l2tp_session_count);
1520
1521 sock_put(tunnel->sock);
1522
1523 /* This will delete the tunnel context if this
1524 * is the last session on the tunnel.
1525 */
1526 session->tunnel = NULL;
1527 l2tp_tunnel_dec_refcount(tunnel);
1528 }
1529
1530 kfree(session);
1531
1532 return;
1533}
1534EXPORT_SYMBOL_GPL(l2tp_session_free);
1535
1536/* This function is used by the netlink SESSION_DELETE command and by
1537 pseudowire modules.
1538 */
1539int l2tp_session_delete(struct l2tp_session *session)
1540{
1541 if (session->session_close != NULL)
1542 (*session->session_close)(session);
1543
1544 l2tp_session_dec_refcount(session);
1545
1546 return 0;
1547}
1548EXPORT_SYMBOL_GPL(l2tp_session_delete);
1549
1550
1551/* We come here whenever a session's send_seq, cookie_len or
1552 * l2specific_len parameters are set.
1553 */
1554static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1555{
1556 if (version == L2TP_HDR_VER_2) {
1557 session->hdr_len = 6;
1558 if (session->send_seq)
1559 session->hdr_len += 4;
1560 } else {
1561 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1562 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1563 session->hdr_len += 4;
1564 }
1565
1566}
1567
1568struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
1569{
1570 struct l2tp_session *session;
1571
1572 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1573 if (session != NULL) {
1574 session->magic = L2TP_SESSION_MAGIC;
1575 session->tunnel = tunnel;
1576
1577 session->session_id = session_id;
1578 session->peer_session_id = peer_session_id;
1579 session->nr = 1;
1580
1581 sprintf(&session->name[0], "sess %u/%u",
1582 tunnel->tunnel_id, session->session_id);
1583
1584 skb_queue_head_init(&session->reorder_q);
1585
1586 INIT_HLIST_NODE(&session->hlist);
1587 INIT_HLIST_NODE(&session->global_hlist);
1588
1589 /* Inherit debug options from tunnel */
1590 session->debug = tunnel->debug;
1591
1592 if (cfg) {
1593 session->pwtype = cfg->pw_type;
1594 session->debug = cfg->debug;
1595 session->mtu = cfg->mtu;
1596 session->mru = cfg->mru;
1597 session->send_seq = cfg->send_seq;
1598 session->recv_seq = cfg->recv_seq;
1599 session->lns_mode = cfg->lns_mode;
1600 session->reorder_timeout = cfg->reorder_timeout;
1601 session->offset = cfg->offset;
1602 session->l2specific_type = cfg->l2specific_type;
1603 session->l2specific_len = cfg->l2specific_len;
1604 session->cookie_len = cfg->cookie_len;
1605 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1606 session->peer_cookie_len = cfg->peer_cookie_len;
1607 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1608 }
1609
1610 if (tunnel->version == L2TP_HDR_VER_2)
1611 session->build_header = l2tp_build_l2tpv2_header;
1612 else
1613 session->build_header = l2tp_build_l2tpv3_header;
1614
1615 l2tp_session_set_header_len(session, tunnel->version);
1616
1617 /* Bump the reference count. The session context is deleted
1618 * only when this drops to zero.
1619 */
1620 l2tp_session_inc_refcount(session);
1621 l2tp_tunnel_inc_refcount(tunnel);
1622
1623 /* Ensure tunnel socket isn't deleted */
1624 sock_hold(tunnel->sock);
1625
1626 /* Add session to the tunnel's hash list */
1627 write_lock_bh(&tunnel->hlist_lock);
1628 hlist_add_head(&session->hlist,
1629 l2tp_session_id_hash(tunnel, session_id));
1630 write_unlock_bh(&tunnel->hlist_lock);
1631
1632 /* And to the global session list if L2TPv3 */
1633 if (tunnel->version != L2TP_HDR_VER_2) {
1634 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1635
1636 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1637 hlist_add_head_rcu(&session->global_hlist,
1638 l2tp_session_id_hash_2(pn, session_id));
1639 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1640 }
1641
1642 /* Ignore management session in session count value */
1643 if (session->session_id != 0)
1644 atomic_inc(&l2tp_session_count);
1645 }
1646
1647 return session;
1648}
1649EXPORT_SYMBOL_GPL(l2tp_session_create);
1650
1651/*****************************************************************************
1652 * Init and cleanup
1653 *****************************************************************************/
1654
1655static __net_init int l2tp_init_net(struct net *net)
1656{
1657 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1658 int hash;
1659
1660 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1661 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1662
1663 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1664 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1665
1666 spin_lock_init(&pn->l2tp_session_hlist_lock);
1667
1668 return 0;
1669}
1670
1671static struct pernet_operations l2tp_net_ops = {
1672 .init = l2tp_init_net,
1673 .id = &l2tp_net_id,
1674 .size = sizeof(struct l2tp_net),
1675};
1676
1677static int __init l2tp_init(void)
1678{
1679 int rc = 0;
1680
1681 rc = register_pernet_device(&l2tp_net_ops);
1682 if (rc)
1683 goto out;
1684
1685 printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);
1686
1687out:
1688 return rc;
1689}
1690
1691static void __exit l2tp_exit(void)
1692{
1693 unregister_pernet_device(&l2tp_net_ops);
1694}
1695
1696module_init(l2tp_init);
1697module_exit(l2tp_exit);
1698
1699MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1700MODULE_DESCRIPTION("L2TP core");
1701MODULE_LICENSE("GPL");
1702MODULE_VERSION(L2TP_DRV_VERSION);
1703
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 */
93struct 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
102static atomic_t l2tp_tunnel_count;
103static atomic_t l2tp_session_count;
104
105/* per-net private data for this module */
106static unsigned int l2tp_net_id;
107struct l2tp_net {
108 struct list_head l2tp_tunnel_list;
109 spinlock_t l2tp_tunnel_list_lock;
110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
111 spinlock_t l2tp_session_hlist_lock;
112};
113
114static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
115static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
116static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
117
118static inline struct l2tp_net *l2tp_pernet(struct net *net)
119{
120 BUG_ON(!net);
121
122 return net_generic(net, l2tp_net_id);
123}
124
125
126/* Tunnel reference counts. Incremented per session that is added to
127 * the tunnel.
128 */
129static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
130{
131 atomic_inc(&tunnel->ref_count);
132}
133
134static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
135{
136 if (atomic_dec_and_test(&tunnel->ref_count))
137 l2tp_tunnel_free(tunnel);
138}
139#ifdef L2TP_REFCNT_DEBUG
140#define l2tp_tunnel_inc_refcount(_t) \
141do { \
142 pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", \
143 __func__, __LINE__, (_t)->name, \
144 atomic_read(&_t->ref_count)); \
145 l2tp_tunnel_inc_refcount_1(_t); \
146} while (0)
147#define l2tp_tunnel_dec_refcount(_t)
148do { \
149 pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", \
150 __func__, __LINE__, (_t)->name, \
151 atomic_read(&_t->ref_count)); \
152 l2tp_tunnel_dec_refcount_1(_t); \
153} while (0)
154#else
155#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
156#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
157#endif
158
159/* Session hash global list for L2TPv3.
160 * The session_id SHOULD be random according to RFC3931, but several
161 * L2TP implementations use incrementing session_ids. So we do a real
162 * hash on the session_id, rather than a simple bitmask.
163 */
164static inline struct hlist_head *
165l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
166{
167 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
168
169}
170
171/* Lookup a session by id in the global session list
172 */
173static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
174{
175 struct l2tp_net *pn = l2tp_pernet(net);
176 struct hlist_head *session_list =
177 l2tp_session_id_hash_2(pn, session_id);
178 struct l2tp_session *session;
179 struct hlist_node *walk;
180
181 rcu_read_lock_bh();
182 hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
183 if (session->session_id == session_id) {
184 rcu_read_unlock_bh();
185 return session;
186 }
187 }
188 rcu_read_unlock_bh();
189
190 return NULL;
191}
192
193/* Session hash list.
194 * The session_id SHOULD be random according to RFC2661, but several
195 * L2TP implementations (Cisco and Microsoft) use incrementing
196 * session_ids. So we do a real hash on the session_id, rather than a
197 * simple bitmask.
198 */
199static inline struct hlist_head *
200l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
201{
202 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
203}
204
205/* Lookup a session by id
206 */
207struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
208{
209 struct hlist_head *session_list;
210 struct l2tp_session *session;
211 struct hlist_node *walk;
212
213 /* In L2TPv3, session_ids are unique over all tunnels and we
214 * sometimes need to look them up before we know the
215 * tunnel.
216 */
217 if (tunnel == NULL)
218 return l2tp_session_find_2(net, session_id);
219
220 session_list = l2tp_session_id_hash(tunnel, session_id);
221 read_lock_bh(&tunnel->hlist_lock);
222 hlist_for_each_entry(session, walk, session_list, hlist) {
223 if (session->session_id == session_id) {
224 read_unlock_bh(&tunnel->hlist_lock);
225 return session;
226 }
227 }
228 read_unlock_bh(&tunnel->hlist_lock);
229
230 return NULL;
231}
232EXPORT_SYMBOL_GPL(l2tp_session_find);
233
234struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
235{
236 int hash;
237 struct hlist_node *walk;
238 struct l2tp_session *session;
239 int count = 0;
240
241 read_lock_bh(&tunnel->hlist_lock);
242 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
243 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
244 if (++count > nth) {
245 read_unlock_bh(&tunnel->hlist_lock);
246 return session;
247 }
248 }
249 }
250
251 read_unlock_bh(&tunnel->hlist_lock);
252
253 return NULL;
254}
255EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
256
257/* Lookup a session by interface name.
258 * This is very inefficient but is only used by management interfaces.
259 */
260struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
261{
262 struct l2tp_net *pn = l2tp_pernet(net);
263 int hash;
264 struct hlist_node *walk;
265 struct l2tp_session *session;
266
267 rcu_read_lock_bh();
268 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
269 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
270 if (!strcmp(session->ifname, ifname)) {
271 rcu_read_unlock_bh();
272 return session;
273 }
274 }
275 }
276
277 rcu_read_unlock_bh();
278
279 return NULL;
280}
281EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
282
283/* Lookup a tunnel by id
284 */
285struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
286{
287 struct l2tp_tunnel *tunnel;
288 struct l2tp_net *pn = l2tp_pernet(net);
289
290 rcu_read_lock_bh();
291 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
292 if (tunnel->tunnel_id == tunnel_id) {
293 rcu_read_unlock_bh();
294 return tunnel;
295 }
296 }
297 rcu_read_unlock_bh();
298
299 return NULL;
300}
301EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
302
303struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
304{
305 struct l2tp_net *pn = l2tp_pernet(net);
306 struct l2tp_tunnel *tunnel;
307 int count = 0;
308
309 rcu_read_lock_bh();
310 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
311 if (++count > nth) {
312 rcu_read_unlock_bh();
313 return tunnel;
314 }
315 }
316
317 rcu_read_unlock_bh();
318
319 return NULL;
320}
321EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
322
323/*****************************************************************************
324 * Receive data handling
325 *****************************************************************************/
326
327/* Queue a skb in order. We come here only if the skb has an L2TP sequence
328 * number.
329 */
330static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
331{
332 struct sk_buff *skbp;
333 struct sk_buff *tmp;
334 u32 ns = L2TP_SKB_CB(skb)->ns;
335 struct l2tp_stats *sstats;
336
337 spin_lock_bh(&session->reorder_q.lock);
338 sstats = &session->stats;
339 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
340 if (L2TP_SKB_CB(skbp)->ns > ns) {
341 __skb_queue_before(&session->reorder_q, skbp, skb);
342 l2tp_dbg(session, L2TP_MSG_SEQ,
343 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
344 session->name, ns, L2TP_SKB_CB(skbp)->ns,
345 skb_queue_len(&session->reorder_q));
346 u64_stats_update_begin(&sstats->syncp);
347 sstats->rx_oos_packets++;
348 u64_stats_update_end(&sstats->syncp);
349 goto out;
350 }
351 }
352
353 __skb_queue_tail(&session->reorder_q, skb);
354
355out:
356 spin_unlock_bh(&session->reorder_q.lock);
357}
358
359/* Dequeue a single skb.
360 */
361static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
362{
363 struct l2tp_tunnel *tunnel = session->tunnel;
364 int length = L2TP_SKB_CB(skb)->length;
365 struct l2tp_stats *tstats, *sstats;
366
367 /* We're about to requeue the skb, so return resources
368 * to its current owner (a socket receive buffer).
369 */
370 skb_orphan(skb);
371
372 tstats = &tunnel->stats;
373 u64_stats_update_begin(&tstats->syncp);
374 sstats = &session->stats;
375 u64_stats_update_begin(&sstats->syncp);
376 tstats->rx_packets++;
377 tstats->rx_bytes += length;
378 sstats->rx_packets++;
379 sstats->rx_bytes += length;
380 u64_stats_update_end(&tstats->syncp);
381 u64_stats_update_end(&sstats->syncp);
382
383 if (L2TP_SKB_CB(skb)->has_seq) {
384 /* Bump our Nr */
385 session->nr++;
386 if (tunnel->version == L2TP_HDR_VER_2)
387 session->nr &= 0xffff;
388 else
389 session->nr &= 0xffffff;
390
391 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
392 session->name, session->nr);
393 }
394
395 /* call private receive handler */
396 if (session->recv_skb != NULL)
397 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
398 else
399 kfree_skb(skb);
400
401 if (session->deref)
402 (*session->deref)(session);
403}
404
405/* Dequeue skbs from the session's reorder_q, subject to packet order.
406 * Skbs that have been in the queue for too long are simply discarded.
407 */
408static void l2tp_recv_dequeue(struct l2tp_session *session)
409{
410 struct sk_buff *skb;
411 struct sk_buff *tmp;
412 struct l2tp_stats *sstats;
413
414 /* If the pkt at the head of the queue has the nr that we
415 * expect to send up next, dequeue it and any other
416 * in-sequence packets behind it.
417 */
418start:
419 spin_lock_bh(&session->reorder_q.lock);
420 sstats = &session->stats;
421 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
422 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
423 u64_stats_update_begin(&sstats->syncp);
424 sstats->rx_seq_discards++;
425 sstats->rx_errors++;
426 u64_stats_update_end(&sstats->syncp);
427 l2tp_dbg(session, L2TP_MSG_SEQ,
428 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
429 session->name, L2TP_SKB_CB(skb)->ns,
430 L2TP_SKB_CB(skb)->length, session->nr,
431 skb_queue_len(&session->reorder_q));
432 session->reorder_skip = 1;
433 __skb_unlink(skb, &session->reorder_q);
434 kfree_skb(skb);
435 if (session->deref)
436 (*session->deref)(session);
437 continue;
438 }
439
440 if (L2TP_SKB_CB(skb)->has_seq) {
441 if (session->reorder_skip) {
442 l2tp_dbg(session, L2TP_MSG_SEQ,
443 "%s: advancing nr to next pkt: %u -> %u",
444 session->name, session->nr,
445 L2TP_SKB_CB(skb)->ns);
446 session->reorder_skip = 0;
447 session->nr = L2TP_SKB_CB(skb)->ns;
448 }
449 if (L2TP_SKB_CB(skb)->ns != session->nr) {
450 l2tp_dbg(session, L2TP_MSG_SEQ,
451 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
452 session->name, L2TP_SKB_CB(skb)->ns,
453 L2TP_SKB_CB(skb)->length, session->nr,
454 skb_queue_len(&session->reorder_q));
455 goto out;
456 }
457 }
458 __skb_unlink(skb, &session->reorder_q);
459
460 /* Process the skb. We release the queue lock while we
461 * do so to let other contexts process the queue.
462 */
463 spin_unlock_bh(&session->reorder_q.lock);
464 l2tp_recv_dequeue_skb(session, skb);
465 goto start;
466 }
467
468out:
469 spin_unlock_bh(&session->reorder_q.lock);
470}
471
472static inline int l2tp_verify_udp_checksum(struct sock *sk,
473 struct sk_buff *skb)
474{
475 struct udphdr *uh = udp_hdr(skb);
476 u16 ulen = ntohs(uh->len);
477 __wsum psum;
478
479 if (sk->sk_no_check || skb_csum_unnecessary(skb))
480 return 0;
481
482#if IS_ENABLED(CONFIG_IPV6)
483 if (sk->sk_family == PF_INET6) {
484 if (!uh->check) {
485 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
486 return 1;
487 }
488 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
489 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
490 &ipv6_hdr(skb)->daddr, ulen,
491 IPPROTO_UDP, skb->csum)) {
492 skb->ip_summed = CHECKSUM_UNNECESSARY;
493 return 0;
494 }
495 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
496 &ipv6_hdr(skb)->daddr,
497 skb->len, IPPROTO_UDP,
498 0));
499 } else
500#endif
501 {
502 struct inet_sock *inet;
503 if (!uh->check)
504 return 0;
505 inet = inet_sk(sk);
506 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
507 ulen, IPPROTO_UDP, 0);
508
509 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
510 !csum_fold(csum_add(psum, skb->csum)))
511 return 0;
512 skb->csum = psum;
513 }
514
515 return __skb_checksum_complete(skb);
516}
517
518/* Do receive processing of L2TP data frames. We handle both L2TPv2
519 * and L2TPv3 data frames here.
520 *
521 * L2TPv2 Data Message Header
522 *
523 * 0 1 2 3
524 * 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
525 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
526 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
527 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
528 * | Tunnel ID | Session ID |
529 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
530 * | Ns (opt) | Nr (opt) |
531 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
532 * | Offset Size (opt) | Offset pad... (opt)
533 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
534 *
535 * Data frames are marked by T=0. All other fields are the same as
536 * those in L2TP control frames.
537 *
538 * L2TPv3 Data Message Header
539 *
540 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
541 * | L2TP Session Header |
542 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
543 * | L2-Specific Sublayer |
544 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
545 * | Tunnel Payload ...
546 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
547 *
548 * L2TPv3 Session Header Over IP
549 *
550 * 0 1 2 3
551 * 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
552 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
553 * | Session ID |
554 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
555 * | Cookie (optional, maximum 64 bits)...
556 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
557 * |
558 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
559 *
560 * L2TPv3 L2-Specific Sublayer Format
561 *
562 * 0 1 2 3
563 * 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
564 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
565 * |x|S|x|x|x|x|x|x| Sequence Number |
566 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
567 *
568 * Cookie value, sublayer format and offset (pad) are negotiated with
569 * the peer when the session is set up. Unlike L2TPv2, we do not need
570 * to parse the packet header to determine if optional fields are
571 * present.
572 *
573 * Caller must already have parsed the frame and determined that it is
574 * a data (not control) frame before coming here. Fields up to the
575 * session-id have already been parsed and ptr points to the data
576 * after the session-id.
577 */
578void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
579 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
580 int length, int (*payload_hook)(struct sk_buff *skb))
581{
582 struct l2tp_tunnel *tunnel = session->tunnel;
583 int offset;
584 u32 ns, nr;
585 struct l2tp_stats *sstats = &session->stats;
586
587 /* The ref count is increased since we now hold a pointer to
588 * the session. Take care to decrement the refcnt when exiting
589 * this function from now on...
590 */
591 l2tp_session_inc_refcount(session);
592 if (session->ref)
593 (*session->ref)(session);
594
595 /* Parse and check optional cookie */
596 if (session->peer_cookie_len > 0) {
597 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
598 l2tp_info(tunnel, L2TP_MSG_DATA,
599 "%s: cookie mismatch (%u/%u). Discarding.\n",
600 tunnel->name, tunnel->tunnel_id,
601 session->session_id);
602 u64_stats_update_begin(&sstats->syncp);
603 sstats->rx_cookie_discards++;
604 u64_stats_update_end(&sstats->syncp);
605 goto discard;
606 }
607 ptr += session->peer_cookie_len;
608 }
609
610 /* Handle the optional sequence numbers. Sequence numbers are
611 * in different places for L2TPv2 and L2TPv3.
612 *
613 * If we are the LAC, enable/disable sequence numbers under
614 * the control of the LNS. If no sequence numbers present but
615 * we were expecting them, discard frame.
616 */
617 ns = nr = 0;
618 L2TP_SKB_CB(skb)->has_seq = 0;
619 if (tunnel->version == L2TP_HDR_VER_2) {
620 if (hdrflags & L2TP_HDRFLAG_S) {
621 ns = ntohs(*(__be16 *) ptr);
622 ptr += 2;
623 nr = ntohs(*(__be16 *) ptr);
624 ptr += 2;
625
626 /* Store L2TP info in the skb */
627 L2TP_SKB_CB(skb)->ns = ns;
628 L2TP_SKB_CB(skb)->has_seq = 1;
629
630 l2tp_dbg(session, L2TP_MSG_SEQ,
631 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
632 session->name, ns, nr, session->nr);
633 }
634 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
635 u32 l2h = ntohl(*(__be32 *) ptr);
636
637 if (l2h & 0x40000000) {
638 ns = l2h & 0x00ffffff;
639
640 /* Store L2TP info in the skb */
641 L2TP_SKB_CB(skb)->ns = ns;
642 L2TP_SKB_CB(skb)->has_seq = 1;
643
644 l2tp_dbg(session, L2TP_MSG_SEQ,
645 "%s: recv data ns=%u, session nr=%u\n",
646 session->name, ns, session->nr);
647 }
648 }
649
650 /* Advance past L2-specific header, if present */
651 ptr += session->l2specific_len;
652
653 if (L2TP_SKB_CB(skb)->has_seq) {
654 /* Received a packet with sequence numbers. If we're the LNS,
655 * check if we sre sending sequence numbers and if not,
656 * configure it so.
657 */
658 if ((!session->lns_mode) && (!session->send_seq)) {
659 l2tp_info(session, L2TP_MSG_SEQ,
660 "%s: requested to enable seq numbers by LNS\n",
661 session->name);
662 session->send_seq = -1;
663 l2tp_session_set_header_len(session, tunnel->version);
664 }
665 } else {
666 /* No sequence numbers.
667 * If user has configured mandatory sequence numbers, discard.
668 */
669 if (session->recv_seq) {
670 l2tp_warn(session, L2TP_MSG_SEQ,
671 "%s: recv data has no seq numbers when required. Discarding.\n",
672 session->name);
673 u64_stats_update_begin(&sstats->syncp);
674 sstats->rx_seq_discards++;
675 u64_stats_update_end(&sstats->syncp);
676 goto discard;
677 }
678
679 /* If we're the LAC and we're sending sequence numbers, the
680 * LNS has requested that we no longer send sequence numbers.
681 * If we're the LNS and we're sending sequence numbers, the
682 * LAC is broken. Discard the frame.
683 */
684 if ((!session->lns_mode) && (session->send_seq)) {
685 l2tp_info(session, L2TP_MSG_SEQ,
686 "%s: requested to disable seq numbers by LNS\n",
687 session->name);
688 session->send_seq = 0;
689 l2tp_session_set_header_len(session, tunnel->version);
690 } else if (session->send_seq) {
691 l2tp_warn(session, L2TP_MSG_SEQ,
692 "%s: recv data has no seq numbers when required. Discarding.\n",
693 session->name);
694 u64_stats_update_begin(&sstats->syncp);
695 sstats->rx_seq_discards++;
696 u64_stats_update_end(&sstats->syncp);
697 goto discard;
698 }
699 }
700
701 /* Session data offset is handled differently for L2TPv2 and
702 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
703 * the header. For L2TPv3, the offset is negotiated using AVPs
704 * in the session setup control protocol.
705 */
706 if (tunnel->version == L2TP_HDR_VER_2) {
707 /* If offset bit set, skip it. */
708 if (hdrflags & L2TP_HDRFLAG_O) {
709 offset = ntohs(*(__be16 *)ptr);
710 ptr += 2 + offset;
711 }
712 } else
713 ptr += session->offset;
714
715 offset = ptr - optr;
716 if (!pskb_may_pull(skb, offset))
717 goto discard;
718
719 __skb_pull(skb, offset);
720
721 /* If caller wants to process the payload before we queue the
722 * packet, do so now.
723 */
724 if (payload_hook)
725 if ((*payload_hook)(skb))
726 goto discard;
727
728 /* Prepare skb for adding to the session's reorder_q. Hold
729 * packets for max reorder_timeout or 1 second if not
730 * reordering.
731 */
732 L2TP_SKB_CB(skb)->length = length;
733 L2TP_SKB_CB(skb)->expires = jiffies +
734 (session->reorder_timeout ? session->reorder_timeout : HZ);
735
736 /* Add packet to the session's receive queue. Reordering is done here, if
737 * enabled. Saved L2TP protocol info is stored in skb->sb[].
738 */
739 if (L2TP_SKB_CB(skb)->has_seq) {
740 if (session->reorder_timeout != 0) {
741 /* Packet reordering enabled. Add skb to session's
742 * reorder queue, in order of ns.
743 */
744 l2tp_recv_queue_skb(session, skb);
745 } else {
746 /* Packet reordering disabled. Discard out-of-sequence
747 * packets
748 */
749 if (L2TP_SKB_CB(skb)->ns != session->nr) {
750 u64_stats_update_begin(&sstats->syncp);
751 sstats->rx_seq_discards++;
752 u64_stats_update_end(&sstats->syncp);
753 l2tp_dbg(session, L2TP_MSG_SEQ,
754 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
755 session->name, L2TP_SKB_CB(skb)->ns,
756 L2TP_SKB_CB(skb)->length, session->nr,
757 skb_queue_len(&session->reorder_q));
758 goto discard;
759 }
760 skb_queue_tail(&session->reorder_q, skb);
761 }
762 } else {
763 /* No sequence numbers. Add the skb to the tail of the
764 * reorder queue. This ensures that it will be
765 * delivered after all previous sequenced skbs.
766 */
767 skb_queue_tail(&session->reorder_q, skb);
768 }
769
770 /* Try to dequeue as many skbs from reorder_q as we can. */
771 l2tp_recv_dequeue(session);
772
773 l2tp_session_dec_refcount(session);
774
775 return;
776
777discard:
778 u64_stats_update_begin(&sstats->syncp);
779 sstats->rx_errors++;
780 u64_stats_update_end(&sstats->syncp);
781 kfree_skb(skb);
782
783 if (session->deref)
784 (*session->deref)(session);
785
786 l2tp_session_dec_refcount(session);
787}
788EXPORT_SYMBOL(l2tp_recv_common);
789
790/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
791 * here. The skb is not on a list when we get here.
792 * Returns 0 if the packet was a data packet and was successfully passed on.
793 * Returns 1 if the packet was not a good data packet and could not be
794 * forwarded. All such packets are passed up to userspace to deal with.
795 */
796static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
797 int (*payload_hook)(struct sk_buff *skb))
798{
799 struct l2tp_session *session = NULL;
800 unsigned char *ptr, *optr;
801 u16 hdrflags;
802 u32 tunnel_id, session_id;
803 u16 version;
804 int length;
805 struct l2tp_stats *tstats;
806
807 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
808 goto discard_bad_csum;
809
810 /* UDP always verifies the packet length. */
811 __skb_pull(skb, sizeof(struct udphdr));
812
813 /* Short packet? */
814 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
815 l2tp_info(tunnel, L2TP_MSG_DATA,
816 "%s: recv short packet (len=%d)\n",
817 tunnel->name, skb->len);
818 goto error;
819 }
820
821 /* Trace packet contents, if enabled */
822 if (tunnel->debug & L2TP_MSG_DATA) {
823 length = min(32u, skb->len);
824 if (!pskb_may_pull(skb, length))
825 goto error;
826
827 pr_debug("%s: recv\n", tunnel->name);
828 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
829 }
830
831 /* Point to L2TP header */
832 optr = ptr = skb->data;
833
834 /* Get L2TP header flags */
835 hdrflags = ntohs(*(__be16 *) ptr);
836
837 /* Check protocol version */
838 version = hdrflags & L2TP_HDR_VER_MASK;
839 if (version != tunnel->version) {
840 l2tp_info(tunnel, L2TP_MSG_DATA,
841 "%s: recv protocol version mismatch: got %d expected %d\n",
842 tunnel->name, version, tunnel->version);
843 goto error;
844 }
845
846 /* Get length of L2TP packet */
847 length = skb->len;
848
849 /* If type is control packet, it is handled by userspace. */
850 if (hdrflags & L2TP_HDRFLAG_T) {
851 l2tp_dbg(tunnel, L2TP_MSG_DATA,
852 "%s: recv control packet, len=%d\n",
853 tunnel->name, length);
854 goto error;
855 }
856
857 /* Skip flags */
858 ptr += 2;
859
860 if (tunnel->version == L2TP_HDR_VER_2) {
861 /* If length is present, skip it */
862 if (hdrflags & L2TP_HDRFLAG_L)
863 ptr += 2;
864
865 /* Extract tunnel and session ID */
866 tunnel_id = ntohs(*(__be16 *) ptr);
867 ptr += 2;
868 session_id = ntohs(*(__be16 *) ptr);
869 ptr += 2;
870 } else {
871 ptr += 2; /* skip reserved bits */
872 tunnel_id = tunnel->tunnel_id;
873 session_id = ntohl(*(__be32 *) ptr);
874 ptr += 4;
875 }
876
877 /* Find the session context */
878 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
879 if (!session || !session->recv_skb) {
880 /* Not found? Pass to userspace to deal with */
881 l2tp_info(tunnel, L2TP_MSG_DATA,
882 "%s: no session found (%u/%u). Passing up.\n",
883 tunnel->name, tunnel_id, session_id);
884 goto error;
885 }
886
887 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
888
889 return 0;
890
891discard_bad_csum:
892 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
893 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
894 tstats = &tunnel->stats;
895 u64_stats_update_begin(&tstats->syncp);
896 tstats->rx_errors++;
897 u64_stats_update_end(&tstats->syncp);
898 kfree_skb(skb);
899
900 return 0;
901
902error:
903 /* Put UDP header back */
904 __skb_push(skb, sizeof(struct udphdr));
905
906 return 1;
907}
908
909/* UDP encapsulation receive handler. See net/ipv4/udp.c.
910 * Return codes:
911 * 0 : success.
912 * <0: error
913 * >0: skb should be passed up to userspace as UDP.
914 */
915int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
916{
917 struct l2tp_tunnel *tunnel;
918
919 tunnel = l2tp_sock_to_tunnel(sk);
920 if (tunnel == NULL)
921 goto pass_up;
922
923 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
924 tunnel->name, skb->len);
925
926 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
927 goto pass_up_put;
928
929 sock_put(sk);
930 return 0;
931
932pass_up_put:
933 sock_put(sk);
934pass_up:
935 return 1;
936}
937EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
938
939/************************************************************************
940 * Transmit handling
941 ***********************************************************************/
942
943/* Build an L2TP header for the session into the buffer provided.
944 */
945static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
946{
947 struct l2tp_tunnel *tunnel = session->tunnel;
948 __be16 *bufp = buf;
949 __be16 *optr = buf;
950 u16 flags = L2TP_HDR_VER_2;
951 u32 tunnel_id = tunnel->peer_tunnel_id;
952 u32 session_id = session->peer_session_id;
953
954 if (session->send_seq)
955 flags |= L2TP_HDRFLAG_S;
956
957 /* Setup L2TP header. */
958 *bufp++ = htons(flags);
959 *bufp++ = htons(tunnel_id);
960 *bufp++ = htons(session_id);
961 if (session->send_seq) {
962 *bufp++ = htons(session->ns);
963 *bufp++ = 0;
964 session->ns++;
965 session->ns &= 0xffff;
966 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
967 session->name, session->ns);
968 }
969
970 return bufp - optr;
971}
972
973static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
974{
975 struct l2tp_tunnel *tunnel = session->tunnel;
976 char *bufp = buf;
977 char *optr = bufp;
978
979 /* Setup L2TP header. The header differs slightly for UDP and
980 * IP encapsulations. For UDP, there is 4 bytes of flags.
981 */
982 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
983 u16 flags = L2TP_HDR_VER_3;
984 *((__be16 *) bufp) = htons(flags);
985 bufp += 2;
986 *((__be16 *) bufp) = 0;
987 bufp += 2;
988 }
989
990 *((__be32 *) bufp) = htonl(session->peer_session_id);
991 bufp += 4;
992 if (session->cookie_len) {
993 memcpy(bufp, &session->cookie[0], session->cookie_len);
994 bufp += session->cookie_len;
995 }
996 if (session->l2specific_len) {
997 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
998 u32 l2h = 0;
999 if (session->send_seq) {
1000 l2h = 0x40000000 | session->ns;
1001 session->ns++;
1002 session->ns &= 0xffffff;
1003 l2tp_dbg(session, L2TP_MSG_SEQ,
1004 "%s: updated ns to %u\n",
1005 session->name, session->ns);
1006 }
1007
1008 *((__be32 *) bufp) = htonl(l2h);
1009 }
1010 bufp += session->l2specific_len;
1011 }
1012 if (session->offset)
1013 bufp += session->offset;
1014
1015 return bufp - optr;
1016}
1017
1018static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1019 struct flowi *fl, size_t data_len)
1020{
1021 struct l2tp_tunnel *tunnel = session->tunnel;
1022 unsigned int len = skb->len;
1023 int error;
1024 struct l2tp_stats *tstats, *sstats;
1025
1026 /* Debug */
1027 if (session->send_seq)
1028 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1029 session->name, data_len, session->ns - 1);
1030 else
1031 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1032 session->name, data_len);
1033
1034 if (session->debug & L2TP_MSG_DATA) {
1035 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1036 unsigned char *datap = skb->data + uhlen;
1037
1038 pr_debug("%s: xmit\n", session->name);
1039 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1040 datap, min_t(size_t, 32, len - uhlen));
1041 }
1042
1043 /* Queue the packet to IP for output */
1044 skb->local_df = 1;
1045#if IS_ENABLED(CONFIG_IPV6)
1046 if (skb->sk->sk_family == PF_INET6)
1047 error = inet6_csk_xmit(skb, NULL);
1048 else
1049#endif
1050 error = ip_queue_xmit(skb, fl);
1051
1052 /* Update stats */
1053 tstats = &tunnel->stats;
1054 u64_stats_update_begin(&tstats->syncp);
1055 sstats = &session->stats;
1056 u64_stats_update_begin(&sstats->syncp);
1057 if (error >= 0) {
1058 tstats->tx_packets++;
1059 tstats->tx_bytes += len;
1060 sstats->tx_packets++;
1061 sstats->tx_bytes += len;
1062 } else {
1063 tstats->tx_errors++;
1064 sstats->tx_errors++;
1065 }
1066 u64_stats_update_end(&tstats->syncp);
1067 u64_stats_update_end(&sstats->syncp);
1068
1069 return 0;
1070}
1071
1072/* Automatically called when the skb is freed.
1073 */
1074static void l2tp_sock_wfree(struct sk_buff *skb)
1075{
1076 sock_put(skb->sk);
1077}
1078
1079/* For data skbs that we transmit, we associate with the tunnel socket
1080 * but don't do accounting.
1081 */
1082static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1083{
1084 sock_hold(sk);
1085 skb->sk = sk;
1086 skb->destructor = l2tp_sock_wfree;
1087}
1088
1089#if IS_ENABLED(CONFIG_IPV6)
1090static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1091 int udp_len)
1092{
1093 struct ipv6_pinfo *np = inet6_sk(sk);
1094 struct udphdr *uh = udp_hdr(skb);
1095
1096 if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1097 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1098 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1099 skb->ip_summed = CHECKSUM_UNNECESSARY;
1100 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1101 IPPROTO_UDP, csum);
1102 if (uh->check == 0)
1103 uh->check = CSUM_MANGLED_0;
1104 } else {
1105 skb->ip_summed = CHECKSUM_PARTIAL;
1106 skb->csum_start = skb_transport_header(skb) - skb->head;
1107 skb->csum_offset = offsetof(struct udphdr, check);
1108 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1109 udp_len, IPPROTO_UDP, 0);
1110 }
1111}
1112#endif
1113
1114/* If caller requires the skb to have a ppp header, the header must be
1115 * inserted in the skb data before calling this function.
1116 */
1117int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1118{
1119 int data_len = skb->len;
1120 struct l2tp_tunnel *tunnel = session->tunnel;
1121 struct sock *sk = tunnel->sock;
1122 struct flowi *fl;
1123 struct udphdr *uh;
1124 struct inet_sock *inet;
1125 __wsum csum;
1126 int old_headroom;
1127 int new_headroom;
1128 int headroom;
1129 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1130 int udp_len;
1131
1132 /* Check that there's enough headroom in the skb to insert IP,
1133 * UDP and L2TP headers. If not enough, expand it to
1134 * make room. Adjust truesize.
1135 */
1136 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1137 uhlen + hdr_len;
1138 old_headroom = skb_headroom(skb);
1139 if (skb_cow_head(skb, headroom)) {
1140 dev_kfree_skb(skb);
1141 goto abort;
1142 }
1143
1144 new_headroom = skb_headroom(skb);
1145 skb_orphan(skb);
1146 skb->truesize += new_headroom - old_headroom;
1147
1148 /* Setup L2TP header */
1149 session->build_header(session, __skb_push(skb, hdr_len));
1150
1151 /* Reset skb netfilter state */
1152 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1153 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1154 IPSKB_REROUTED);
1155 nf_reset(skb);
1156
1157 bh_lock_sock(sk);
1158 if (sock_owned_by_user(sk)) {
1159 dev_kfree_skb(skb);
1160 goto out_unlock;
1161 }
1162
1163 /* Get routing info from the tunnel socket */
1164 skb_dst_drop(skb);
1165 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1166
1167 inet = inet_sk(sk);
1168 fl = &inet->cork.fl;
1169 switch (tunnel->encap) {
1170 case L2TP_ENCAPTYPE_UDP:
1171 /* Setup UDP header */
1172 __skb_push(skb, sizeof(*uh));
1173 skb_reset_transport_header(skb);
1174 uh = udp_hdr(skb);
1175 uh->source = inet->inet_sport;
1176 uh->dest = inet->inet_dport;
1177 udp_len = uhlen + hdr_len + data_len;
1178 uh->len = htons(udp_len);
1179 uh->check = 0;
1180
1181 /* Calculate UDP checksum if configured to do so */
1182#if IS_ENABLED(CONFIG_IPV6)
1183 if (sk->sk_family == PF_INET6)
1184 l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1185 else
1186#endif
1187 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1188 skb->ip_summed = CHECKSUM_NONE;
1189 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1190 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1191 skb->ip_summed = CHECKSUM_COMPLETE;
1192 csum = skb_checksum(skb, 0, udp_len, 0);
1193 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1194 inet->inet_daddr,
1195 udp_len, IPPROTO_UDP, csum);
1196 if (uh->check == 0)
1197 uh->check = CSUM_MANGLED_0;
1198 } else {
1199 skb->ip_summed = CHECKSUM_PARTIAL;
1200 skb->csum_start = skb_transport_header(skb) - skb->head;
1201 skb->csum_offset = offsetof(struct udphdr, check);
1202 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1203 inet->inet_daddr,
1204 udp_len, IPPROTO_UDP, 0);
1205 }
1206 break;
1207
1208 case L2TP_ENCAPTYPE_IP:
1209 break;
1210 }
1211
1212 l2tp_skb_set_owner_w(skb, sk);
1213
1214 l2tp_xmit_core(session, skb, fl, data_len);
1215out_unlock:
1216 bh_unlock_sock(sk);
1217
1218abort:
1219 return 0;
1220}
1221EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1222
1223/*****************************************************************************
1224 * Tinnel and session create/destroy.
1225 *****************************************************************************/
1226
1227/* Tunnel socket destruct hook.
1228 * The tunnel context is deleted only when all session sockets have been
1229 * closed.
1230 */
1231static void l2tp_tunnel_destruct(struct sock *sk)
1232{
1233 struct l2tp_tunnel *tunnel;
1234
1235 tunnel = sk->sk_user_data;
1236 if (tunnel == NULL)
1237 goto end;
1238
1239 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1240
1241 /* Close all sessions */
1242 l2tp_tunnel_closeall(tunnel);
1243
1244 switch (tunnel->encap) {
1245 case L2TP_ENCAPTYPE_UDP:
1246 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1247 (udp_sk(sk))->encap_type = 0;
1248 (udp_sk(sk))->encap_rcv = NULL;
1249 break;
1250 case L2TP_ENCAPTYPE_IP:
1251 break;
1252 }
1253
1254 /* Remove hooks into tunnel socket */
1255 tunnel->sock = NULL;
1256 sk->sk_destruct = tunnel->old_sk_destruct;
1257 sk->sk_user_data = NULL;
1258
1259 /* Call the original destructor */
1260 if (sk->sk_destruct)
1261 (*sk->sk_destruct)(sk);
1262
1263 /* We're finished with the socket */
1264 l2tp_tunnel_dec_refcount(tunnel);
1265
1266end:
1267 return;
1268}
1269
1270/* When the tunnel is closed, all the attached sessions need to go too.
1271 */
1272static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1273{
1274 int hash;
1275 struct hlist_node *walk;
1276 struct hlist_node *tmp;
1277 struct l2tp_session *session;
1278
1279 BUG_ON(tunnel == NULL);
1280
1281 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1282 tunnel->name);
1283
1284 write_lock_bh(&tunnel->hlist_lock);
1285 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1286again:
1287 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1288 session = hlist_entry(walk, struct l2tp_session, hlist);
1289
1290 l2tp_info(session, L2TP_MSG_CONTROL,
1291 "%s: closing session\n", session->name);
1292
1293 hlist_del_init(&session->hlist);
1294
1295 /* Since we should hold the sock lock while
1296 * doing any unbinding, we need to release the
1297 * lock we're holding before taking that lock.
1298 * Hold a reference to the sock so it doesn't
1299 * disappear as we're jumping between locks.
1300 */
1301 if (session->ref != NULL)
1302 (*session->ref)(session);
1303
1304 write_unlock_bh(&tunnel->hlist_lock);
1305
1306 if (tunnel->version != L2TP_HDR_VER_2) {
1307 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1308
1309 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1310 hlist_del_init_rcu(&session->global_hlist);
1311 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1312 synchronize_rcu();
1313 }
1314
1315 if (session->session_close != NULL)
1316 (*session->session_close)(session);
1317
1318 if (session->deref != NULL)
1319 (*session->deref)(session);
1320
1321 write_lock_bh(&tunnel->hlist_lock);
1322
1323 /* Now restart from the beginning of this hash
1324 * chain. We always remove a session from the
1325 * list so we are guaranteed to make forward
1326 * progress.
1327 */
1328 goto again;
1329 }
1330 }
1331 write_unlock_bh(&tunnel->hlist_lock);
1332}
1333
1334/* Really kill the tunnel.
1335 * Come here only when all sessions have been cleared from the tunnel.
1336 */
1337static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1338{
1339 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1340
1341 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1342 BUG_ON(tunnel->sock != NULL);
1343
1344 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1345
1346 /* Remove from tunnel list */
1347 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1348 list_del_rcu(&tunnel->list);
1349 kfree_rcu(tunnel, rcu);
1350 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1351
1352 atomic_dec(&l2tp_tunnel_count);
1353}
1354
1355/* Create a socket for the tunnel, if one isn't set up by
1356 * userspace. This is used for static tunnels where there is no
1357 * managing L2TP daemon.
1358 */
1359static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1360{
1361 int err = -EINVAL;
1362 struct sockaddr_in udp_addr;
1363#if IS_ENABLED(CONFIG_IPV6)
1364 struct sockaddr_in6 udp6_addr;
1365 struct sockaddr_l2tpip6 ip6_addr;
1366#endif
1367 struct sockaddr_l2tpip ip_addr;
1368 struct socket *sock = NULL;
1369
1370 switch (cfg->encap) {
1371 case L2TP_ENCAPTYPE_UDP:
1372#if IS_ENABLED(CONFIG_IPV6)
1373 if (cfg->local_ip6 && cfg->peer_ip6) {
1374 err = sock_create(AF_INET6, SOCK_DGRAM, 0, sockp);
1375 if (err < 0)
1376 goto out;
1377
1378 sock = *sockp;
1379
1380 memset(&udp6_addr, 0, sizeof(udp6_addr));
1381 udp6_addr.sin6_family = AF_INET6;
1382 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1383 sizeof(udp6_addr.sin6_addr));
1384 udp6_addr.sin6_port = htons(cfg->local_udp_port);
1385 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1386 sizeof(udp6_addr));
1387 if (err < 0)
1388 goto out;
1389
1390 udp6_addr.sin6_family = AF_INET6;
1391 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1392 sizeof(udp6_addr.sin6_addr));
1393 udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1394 err = kernel_connect(sock,
1395 (struct sockaddr *) &udp6_addr,
1396 sizeof(udp6_addr), 0);
1397 if (err < 0)
1398 goto out;
1399 } else
1400#endif
1401 {
1402 err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1403 if (err < 0)
1404 goto out;
1405
1406 sock = *sockp;
1407
1408 memset(&udp_addr, 0, sizeof(udp_addr));
1409 udp_addr.sin_family = AF_INET;
1410 udp_addr.sin_addr = cfg->local_ip;
1411 udp_addr.sin_port = htons(cfg->local_udp_port);
1412 err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1413 sizeof(udp_addr));
1414 if (err < 0)
1415 goto out;
1416
1417 udp_addr.sin_family = AF_INET;
1418 udp_addr.sin_addr = cfg->peer_ip;
1419 udp_addr.sin_port = htons(cfg->peer_udp_port);
1420 err = kernel_connect(sock,
1421 (struct sockaddr *) &udp_addr,
1422 sizeof(udp_addr), 0);
1423 if (err < 0)
1424 goto out;
1425 }
1426
1427 if (!cfg->use_udp_checksums)
1428 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1429
1430 break;
1431
1432 case L2TP_ENCAPTYPE_IP:
1433#if IS_ENABLED(CONFIG_IPV6)
1434 if (cfg->local_ip6 && cfg->peer_ip6) {
1435 err = sock_create(AF_INET6, SOCK_DGRAM, IPPROTO_L2TP,
1436 sockp);
1437 if (err < 0)
1438 goto out;
1439
1440 sock = *sockp;
1441
1442 memset(&ip6_addr, 0, sizeof(ip6_addr));
1443 ip6_addr.l2tp_family = AF_INET6;
1444 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1445 sizeof(ip6_addr.l2tp_addr));
1446 ip6_addr.l2tp_conn_id = tunnel_id;
1447 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1448 sizeof(ip6_addr));
1449 if (err < 0)
1450 goto out;
1451
1452 ip6_addr.l2tp_family = AF_INET6;
1453 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1454 sizeof(ip6_addr.l2tp_addr));
1455 ip6_addr.l2tp_conn_id = peer_tunnel_id;
1456 err = kernel_connect(sock,
1457 (struct sockaddr *) &ip6_addr,
1458 sizeof(ip6_addr), 0);
1459 if (err < 0)
1460 goto out;
1461 } else
1462#endif
1463 {
1464 err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP,
1465 sockp);
1466 if (err < 0)
1467 goto out;
1468
1469 sock = *sockp;
1470
1471 memset(&ip_addr, 0, sizeof(ip_addr));
1472 ip_addr.l2tp_family = AF_INET;
1473 ip_addr.l2tp_addr = cfg->local_ip;
1474 ip_addr.l2tp_conn_id = tunnel_id;
1475 err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1476 sizeof(ip_addr));
1477 if (err < 0)
1478 goto out;
1479
1480 ip_addr.l2tp_family = AF_INET;
1481 ip_addr.l2tp_addr = cfg->peer_ip;
1482 ip_addr.l2tp_conn_id = peer_tunnel_id;
1483 err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1484 sizeof(ip_addr), 0);
1485 if (err < 0)
1486 goto out;
1487 }
1488 break;
1489
1490 default:
1491 goto out;
1492 }
1493
1494out:
1495 if ((err < 0) && sock) {
1496 sock_release(sock);
1497 *sockp = NULL;
1498 }
1499
1500 return err;
1501}
1502
1503int 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)
1504{
1505 struct l2tp_tunnel *tunnel = NULL;
1506 int err;
1507 struct socket *sock = NULL;
1508 struct sock *sk = NULL;
1509 struct l2tp_net *pn;
1510 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1511
1512 /* Get the tunnel socket from the fd, which was opened by
1513 * the userspace L2TP daemon. If not specified, create a
1514 * kernel socket.
1515 */
1516 if (fd < 0) {
1517 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1518 if (err < 0)
1519 goto err;
1520 } else {
1521 err = -EBADF;
1522 sock = sockfd_lookup(fd, &err);
1523 if (!sock) {
1524 pr_err("tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1525 tunnel_id, fd, err);
1526 goto err;
1527 }
1528 }
1529
1530 sk = sock->sk;
1531
1532 if (cfg != NULL)
1533 encap = cfg->encap;
1534
1535 /* Quick sanity checks */
1536 switch (encap) {
1537 case L2TP_ENCAPTYPE_UDP:
1538 err = -EPROTONOSUPPORT;
1539 if (sk->sk_protocol != IPPROTO_UDP) {
1540 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1541 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1542 goto err;
1543 }
1544 break;
1545 case L2TP_ENCAPTYPE_IP:
1546 err = -EPROTONOSUPPORT;
1547 if (sk->sk_protocol != IPPROTO_L2TP) {
1548 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1549 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1550 goto err;
1551 }
1552 break;
1553 }
1554
1555 /* Check if this socket has already been prepped */
1556 tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1557 if (tunnel != NULL) {
1558 /* This socket has already been prepped */
1559 err = -EBUSY;
1560 goto err;
1561 }
1562
1563 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1564 if (tunnel == NULL) {
1565 err = -ENOMEM;
1566 goto err;
1567 }
1568
1569 tunnel->version = version;
1570 tunnel->tunnel_id = tunnel_id;
1571 tunnel->peer_tunnel_id = peer_tunnel_id;
1572 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1573
1574 tunnel->magic = L2TP_TUNNEL_MAGIC;
1575 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1576 rwlock_init(&tunnel->hlist_lock);
1577
1578 /* The net we belong to */
1579 tunnel->l2tp_net = net;
1580 pn = l2tp_pernet(net);
1581
1582 if (cfg != NULL)
1583 tunnel->debug = cfg->debug;
1584
1585 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1586 tunnel->encap = encap;
1587 if (encap == L2TP_ENCAPTYPE_UDP) {
1588 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1589 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1590 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1591#if IS_ENABLED(CONFIG_IPV6)
1592 if (sk->sk_family == PF_INET6)
1593 udpv6_encap_enable();
1594 else
1595#endif
1596 udp_encap_enable();
1597 }
1598
1599 sk->sk_user_data = tunnel;
1600
1601 /* Hook on the tunnel socket destructor so that we can cleanup
1602 * if the tunnel socket goes away.
1603 */
1604 tunnel->old_sk_destruct = sk->sk_destruct;
1605 sk->sk_destruct = &l2tp_tunnel_destruct;
1606 tunnel->sock = sk;
1607 sk->sk_allocation = GFP_ATOMIC;
1608
1609 /* Add tunnel to our list */
1610 INIT_LIST_HEAD(&tunnel->list);
1611 atomic_inc(&l2tp_tunnel_count);
1612
1613 /* Bump the reference count. The tunnel context is deleted
1614 * only when this drops to zero. Must be done before list insertion
1615 */
1616 l2tp_tunnel_inc_refcount(tunnel);
1617 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1618 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1619 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1620
1621 err = 0;
1622err:
1623 if (tunnelp)
1624 *tunnelp = tunnel;
1625
1626 /* If tunnel's socket was created by the kernel, it doesn't
1627 * have a file.
1628 */
1629 if (sock && sock->file)
1630 sockfd_put(sock);
1631
1632 return err;
1633}
1634EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1635
1636/* This function is used by the netlink TUNNEL_DELETE command.
1637 */
1638int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1639{
1640 int err = 0;
1641 struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
1642
1643 /* Force the tunnel socket to close. This will eventually
1644 * cause the tunnel to be deleted via the normal socket close
1645 * mechanisms when userspace closes the tunnel socket.
1646 */
1647 if (sock != NULL) {
1648 err = inet_shutdown(sock, 2);
1649
1650 /* If the tunnel's socket was created by the kernel,
1651 * close the socket here since the socket was not
1652 * created by userspace.
1653 */
1654 if (sock->file == NULL)
1655 err = inet_release(sock);
1656 }
1657
1658 return err;
1659}
1660EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1661
1662/* Really kill the session.
1663 */
1664void l2tp_session_free(struct l2tp_session *session)
1665{
1666 struct l2tp_tunnel *tunnel;
1667
1668 BUG_ON(atomic_read(&session->ref_count) != 0);
1669
1670 tunnel = session->tunnel;
1671 if (tunnel != NULL) {
1672 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1673
1674 /* Delete the session from the hash */
1675 write_lock_bh(&tunnel->hlist_lock);
1676 hlist_del_init(&session->hlist);
1677 write_unlock_bh(&tunnel->hlist_lock);
1678
1679 /* Unlink from the global hash if not L2TPv2 */
1680 if (tunnel->version != L2TP_HDR_VER_2) {
1681 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1682
1683 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1684 hlist_del_init_rcu(&session->global_hlist);
1685 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1686 synchronize_rcu();
1687 }
1688
1689 if (session->session_id != 0)
1690 atomic_dec(&l2tp_session_count);
1691
1692 sock_put(tunnel->sock);
1693
1694 /* This will delete the tunnel context if this
1695 * is the last session on the tunnel.
1696 */
1697 session->tunnel = NULL;
1698 l2tp_tunnel_dec_refcount(tunnel);
1699 }
1700
1701 kfree(session);
1702
1703 return;
1704}
1705EXPORT_SYMBOL_GPL(l2tp_session_free);
1706
1707/* This function is used by the netlink SESSION_DELETE command and by
1708 pseudowire modules.
1709 */
1710int l2tp_session_delete(struct l2tp_session *session)
1711{
1712 if (session->session_close != NULL)
1713 (*session->session_close)(session);
1714
1715 l2tp_session_dec_refcount(session);
1716
1717 return 0;
1718}
1719EXPORT_SYMBOL_GPL(l2tp_session_delete);
1720
1721
1722/* We come here whenever a session's send_seq, cookie_len or
1723 * l2specific_len parameters are set.
1724 */
1725static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1726{
1727 if (version == L2TP_HDR_VER_2) {
1728 session->hdr_len = 6;
1729 if (session->send_seq)
1730 session->hdr_len += 4;
1731 } else {
1732 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1733 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1734 session->hdr_len += 4;
1735 }
1736
1737}
1738
1739struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
1740{
1741 struct l2tp_session *session;
1742
1743 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1744 if (session != NULL) {
1745 session->magic = L2TP_SESSION_MAGIC;
1746 session->tunnel = tunnel;
1747
1748 session->session_id = session_id;
1749 session->peer_session_id = peer_session_id;
1750 session->nr = 0;
1751
1752 sprintf(&session->name[0], "sess %u/%u",
1753 tunnel->tunnel_id, session->session_id);
1754
1755 skb_queue_head_init(&session->reorder_q);
1756
1757 INIT_HLIST_NODE(&session->hlist);
1758 INIT_HLIST_NODE(&session->global_hlist);
1759
1760 /* Inherit debug options from tunnel */
1761 session->debug = tunnel->debug;
1762
1763 if (cfg) {
1764 session->pwtype = cfg->pw_type;
1765 session->debug = cfg->debug;
1766 session->mtu = cfg->mtu;
1767 session->mru = cfg->mru;
1768 session->send_seq = cfg->send_seq;
1769 session->recv_seq = cfg->recv_seq;
1770 session->lns_mode = cfg->lns_mode;
1771 session->reorder_timeout = cfg->reorder_timeout;
1772 session->offset = cfg->offset;
1773 session->l2specific_type = cfg->l2specific_type;
1774 session->l2specific_len = cfg->l2specific_len;
1775 session->cookie_len = cfg->cookie_len;
1776 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1777 session->peer_cookie_len = cfg->peer_cookie_len;
1778 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1779 }
1780
1781 if (tunnel->version == L2TP_HDR_VER_2)
1782 session->build_header = l2tp_build_l2tpv2_header;
1783 else
1784 session->build_header = l2tp_build_l2tpv3_header;
1785
1786 l2tp_session_set_header_len(session, tunnel->version);
1787
1788 /* Bump the reference count. The session context is deleted
1789 * only when this drops to zero.
1790 */
1791 l2tp_session_inc_refcount(session);
1792 l2tp_tunnel_inc_refcount(tunnel);
1793
1794 /* Ensure tunnel socket isn't deleted */
1795 sock_hold(tunnel->sock);
1796
1797 /* Add session to the tunnel's hash list */
1798 write_lock_bh(&tunnel->hlist_lock);
1799 hlist_add_head(&session->hlist,
1800 l2tp_session_id_hash(tunnel, session_id));
1801 write_unlock_bh(&tunnel->hlist_lock);
1802
1803 /* And to the global session list if L2TPv3 */
1804 if (tunnel->version != L2TP_HDR_VER_2) {
1805 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1806
1807 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1808 hlist_add_head_rcu(&session->global_hlist,
1809 l2tp_session_id_hash_2(pn, session_id));
1810 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1811 }
1812
1813 /* Ignore management session in session count value */
1814 if (session->session_id != 0)
1815 atomic_inc(&l2tp_session_count);
1816 }
1817
1818 return session;
1819}
1820EXPORT_SYMBOL_GPL(l2tp_session_create);
1821
1822/*****************************************************************************
1823 * Init and cleanup
1824 *****************************************************************************/
1825
1826static __net_init int l2tp_init_net(struct net *net)
1827{
1828 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1829 int hash;
1830
1831 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1832 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1833
1834 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1835 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1836
1837 spin_lock_init(&pn->l2tp_session_hlist_lock);
1838
1839 return 0;
1840}
1841
1842static struct pernet_operations l2tp_net_ops = {
1843 .init = l2tp_init_net,
1844 .id = &l2tp_net_id,
1845 .size = sizeof(struct l2tp_net),
1846};
1847
1848static int __init l2tp_init(void)
1849{
1850 int rc = 0;
1851
1852 rc = register_pernet_device(&l2tp_net_ops);
1853 if (rc)
1854 goto out;
1855
1856 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1857
1858out:
1859 return rc;
1860}
1861
1862static void __exit l2tp_exit(void)
1863{
1864 unregister_pernet_device(&l2tp_net_ops);
1865}
1866
1867module_init(l2tp_init);
1868module_exit(l2tp_exit);
1869
1870MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1871MODULE_DESCRIPTION("L2TP core");
1872MODULE_LICENSE("GPL");
1873MODULE_VERSION(L2TP_DRV_VERSION);
1874