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fd558d18
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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>
e02d494d 24#include <linux/rculist.h>
fd558d18
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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>
0d76751f 40#include <linux/in.h>
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41#include <linux/ip.h>
42#include <linux/udp.h>
0d76751f 43#include <linux/l2tp.h>
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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>
309795f4 53#include <net/inet_common.h>
fd558d18 54#include <net/xfrm.h>
0d76751f 55#include <net/protocol.h>
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56
57#include <asm/byteorder.h>
58#include <asm/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
f7faffa3 73#define L2TP_HDR_VER_3 0x0003
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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 {
f7faffa3 94 u32 ns;
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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;
e02d494d 109 spinlock_t l2tp_tunnel_list_lock;
f7faffa3 110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
e02d494d 111 spinlock_t l2tp_session_hlist_lock;
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112};
113
114static inline struct l2tp_net *l2tp_pernet(struct net *net)
115{
116 BUG_ON(!net);
117
118 return net_generic(net, l2tp_net_id);
119}
120
f7faffa3
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121/* Session hash global list for L2TPv3.
122 * The session_id SHOULD be random according to RFC3931, but several
123 * L2TP implementations use incrementing session_ids. So we do a real
124 * hash on the session_id, rather than a simple bitmask.
125 */
126static inline struct hlist_head *
127l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
128{
129 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
130
131}
132
133/* Lookup a session by id in the global session list
134 */
135static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
136{
137 struct l2tp_net *pn = l2tp_pernet(net);
138 struct hlist_head *session_list =
139 l2tp_session_id_hash_2(pn, session_id);
140 struct l2tp_session *session;
141 struct hlist_node *walk;
142
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143 rcu_read_lock_bh();
144 hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
f7faffa3 145 if (session->session_id == session_id) {
e02d494d 146 rcu_read_unlock_bh();
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147 return session;
148 }
149 }
e02d494d 150 rcu_read_unlock_bh();
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151
152 return NULL;
153}
154
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155/* Session hash list.
156 * The session_id SHOULD be random according to RFC2661, but several
157 * L2TP implementations (Cisco and Microsoft) use incrementing
158 * session_ids. So we do a real hash on the session_id, rather than a
159 * simple bitmask.
160 */
161static inline struct hlist_head *
162l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
163{
164 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
165}
166
167/* Lookup a session by id
168 */
f7faffa3 169struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
fd558d18 170{
f7faffa3 171 struct hlist_head *session_list;
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172 struct l2tp_session *session;
173 struct hlist_node *walk;
174
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175 /* In L2TPv3, session_ids are unique over all tunnels and we
176 * sometimes need to look them up before we know the
177 * tunnel.
178 */
179 if (tunnel == NULL)
180 return l2tp_session_find_2(net, session_id);
181
182 session_list = l2tp_session_id_hash(tunnel, session_id);
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183 read_lock_bh(&tunnel->hlist_lock);
184 hlist_for_each_entry(session, walk, session_list, hlist) {
185 if (session->session_id == session_id) {
186 read_unlock_bh(&tunnel->hlist_lock);
187 return session;
188 }
189 }
190 read_unlock_bh(&tunnel->hlist_lock);
191
192 return NULL;
193}
194EXPORT_SYMBOL_GPL(l2tp_session_find);
195
196struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
197{
198 int hash;
199 struct hlist_node *walk;
200 struct l2tp_session *session;
201 int count = 0;
202
203 read_lock_bh(&tunnel->hlist_lock);
204 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
205 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
206 if (++count > nth) {
207 read_unlock_bh(&tunnel->hlist_lock);
208 return session;
209 }
210 }
211 }
212
213 read_unlock_bh(&tunnel->hlist_lock);
214
215 return NULL;
216}
217EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
218
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219/* Lookup a session by interface name.
220 * This is very inefficient but is only used by management interfaces.
221 */
222struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
223{
224 struct l2tp_net *pn = l2tp_pernet(net);
225 int hash;
226 struct hlist_node *walk;
227 struct l2tp_session *session;
228
e02d494d 229 rcu_read_lock_bh();
309795f4 230 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
e02d494d 231 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
309795f4 232 if (!strcmp(session->ifname, ifname)) {
e02d494d 233 rcu_read_unlock_bh();
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234 return session;
235 }
236 }
237 }
238
e02d494d 239 rcu_read_unlock_bh();
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240
241 return NULL;
242}
243EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
244
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245/* Lookup a tunnel by id
246 */
247struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
248{
249 struct l2tp_tunnel *tunnel;
250 struct l2tp_net *pn = l2tp_pernet(net);
251
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252 rcu_read_lock_bh();
253 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
fd558d18 254 if (tunnel->tunnel_id == tunnel_id) {
e02d494d 255 rcu_read_unlock_bh();
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256 return tunnel;
257 }
258 }
e02d494d 259 rcu_read_unlock_bh();
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260
261 return NULL;
262}
263EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
264
265struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
266{
267 struct l2tp_net *pn = l2tp_pernet(net);
268 struct l2tp_tunnel *tunnel;
269 int count = 0;
270
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271 rcu_read_lock_bh();
272 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
fd558d18 273 if (++count > nth) {
e02d494d 274 rcu_read_unlock_bh();
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275 return tunnel;
276 }
277 }
278
e02d494d 279 rcu_read_unlock_bh();
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280
281 return NULL;
282}
283EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
284
285/*****************************************************************************
286 * Receive data handling
287 *****************************************************************************/
288
289/* Queue a skb in order. We come here only if the skb has an L2TP sequence
290 * number.
291 */
292static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
293{
294 struct sk_buff *skbp;
295 struct sk_buff *tmp;
f7faffa3 296 u32 ns = L2TP_SKB_CB(skb)->ns;
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297
298 spin_lock_bh(&session->reorder_q.lock);
299 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
300 if (L2TP_SKB_CB(skbp)->ns > ns) {
301 __skb_queue_before(&session->reorder_q, skbp, skb);
302 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
303 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
304 session->name, ns, L2TP_SKB_CB(skbp)->ns,
305 skb_queue_len(&session->reorder_q));
306 session->stats.rx_oos_packets++;
307 goto out;
308 }
309 }
310
311 __skb_queue_tail(&session->reorder_q, skb);
312
313out:
314 spin_unlock_bh(&session->reorder_q.lock);
315}
316
317/* Dequeue a single skb.
318 */
319static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
320{
321 struct l2tp_tunnel *tunnel = session->tunnel;
322 int length = L2TP_SKB_CB(skb)->length;
323
324 /* We're about to requeue the skb, so return resources
325 * to its current owner (a socket receive buffer).
326 */
327 skb_orphan(skb);
328
329 tunnel->stats.rx_packets++;
330 tunnel->stats.rx_bytes += length;
331 session->stats.rx_packets++;
332 session->stats.rx_bytes += length;
333
334 if (L2TP_SKB_CB(skb)->has_seq) {
335 /* Bump our Nr */
336 session->nr++;
f7faffa3
JC
337 if (tunnel->version == L2TP_HDR_VER_2)
338 session->nr &= 0xffff;
339 else
340 session->nr &= 0xffffff;
341
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342 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
343 "%s: updated nr to %hu\n", session->name, session->nr);
344 }
345
346 /* call private receive handler */
347 if (session->recv_skb != NULL)
348 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
349 else
350 kfree_skb(skb);
351
352 if (session->deref)
353 (*session->deref)(session);
354}
355
356/* Dequeue skbs from the session's reorder_q, subject to packet order.
357 * Skbs that have been in the queue for too long are simply discarded.
358 */
359static void l2tp_recv_dequeue(struct l2tp_session *session)
360{
361 struct sk_buff *skb;
362 struct sk_buff *tmp;
363
364 /* If the pkt at the head of the queue has the nr that we
365 * expect to send up next, dequeue it and any other
366 * in-sequence packets behind it.
367 */
368 spin_lock_bh(&session->reorder_q.lock);
369 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
370 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
371 session->stats.rx_seq_discards++;
372 session->stats.rx_errors++;
373 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
f7faffa3
JC
374 "%s: oos pkt %u len %d discarded (too old), "
375 "waiting for %u, reorder_q_len=%d\n",
fd558d18
JC
376 session->name, L2TP_SKB_CB(skb)->ns,
377 L2TP_SKB_CB(skb)->length, session->nr,
378 skb_queue_len(&session->reorder_q));
379 __skb_unlink(skb, &session->reorder_q);
380 kfree_skb(skb);
381 if (session->deref)
382 (*session->deref)(session);
383 continue;
384 }
385
386 if (L2TP_SKB_CB(skb)->has_seq) {
387 if (L2TP_SKB_CB(skb)->ns != session->nr) {
388 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
f7faffa3
JC
389 "%s: holding oos pkt %u len %d, "
390 "waiting for %u, reorder_q_len=%d\n",
fd558d18
JC
391 session->name, L2TP_SKB_CB(skb)->ns,
392 L2TP_SKB_CB(skb)->length, session->nr,
393 skb_queue_len(&session->reorder_q));
394 goto out;
395 }
396 }
397 __skb_unlink(skb, &session->reorder_q);
398
399 /* Process the skb. We release the queue lock while we
400 * do so to let other contexts process the queue.
401 */
402 spin_unlock_bh(&session->reorder_q.lock);
403 l2tp_recv_dequeue_skb(session, skb);
404 spin_lock_bh(&session->reorder_q.lock);
405 }
406
407out:
408 spin_unlock_bh(&session->reorder_q.lock);
409}
410
411static inline int l2tp_verify_udp_checksum(struct sock *sk,
412 struct sk_buff *skb)
413{
414 struct udphdr *uh = udp_hdr(skb);
415 u16 ulen = ntohs(uh->len);
416 struct inet_sock *inet;
417 __wsum psum;
418
419 if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
420 return 0;
421
422 inet = inet_sk(sk);
423 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
424 IPPROTO_UDP, 0);
425
426 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
427 !csum_fold(csum_add(psum, skb->csum)))
428 return 0;
429
430 skb->csum = psum;
431
432 return __skb_checksum_complete(skb);
433}
434
f7faffa3
JC
435/* Do receive processing of L2TP data frames. We handle both L2TPv2
436 * and L2TPv3 data frames here.
437 *
438 * L2TPv2 Data Message Header
439 *
440 * 0 1 2 3
441 * 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
442 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
443 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
444 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
445 * | Tunnel ID | Session ID |
446 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
447 * | Ns (opt) | Nr (opt) |
448 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
449 * | Offset Size (opt) | Offset pad... (opt)
450 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
451 *
452 * Data frames are marked by T=0. All other fields are the same as
453 * those in L2TP control frames.
454 *
455 * L2TPv3 Data Message Header
456 *
457 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
458 * | L2TP Session Header |
459 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
460 * | L2-Specific Sublayer |
461 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
462 * | Tunnel Payload ...
463 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
464 *
465 * L2TPv3 Session Header Over IP
466 *
467 * 0 1 2 3
468 * 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
469 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
470 * | Session ID |
471 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
472 * | Cookie (optional, maximum 64 bits)...
473 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
474 * |
475 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
476 *
477 * L2TPv3 L2-Specific Sublayer Format
478 *
479 * 0 1 2 3
480 * 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
481 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
482 * |x|S|x|x|x|x|x|x| Sequence Number |
483 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
484 *
485 * Cookie value, sublayer format and offset (pad) are negotiated with
486 * the peer when the session is set up. Unlike L2TPv2, we do not need
487 * to parse the packet header to determine if optional fields are
488 * present.
489 *
490 * Caller must already have parsed the frame and determined that it is
491 * a data (not control) frame before coming here. Fields up to the
492 * session-id have already been parsed and ptr points to the data
493 * after the session-id.
fd558d18 494 */
f7faffa3
JC
495void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
496 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
497 int length, int (*payload_hook)(struct sk_buff *skb))
fd558d18 498{
f7faffa3 499 struct l2tp_tunnel *tunnel = session->tunnel;
fd558d18 500 int offset;
f7faffa3 501 u32 ns, nr;
fd558d18
JC
502
503 /* The ref count is increased since we now hold a pointer to
504 * the session. Take care to decrement the refcnt when exiting
505 * this function from now on...
506 */
507 l2tp_session_inc_refcount(session);
508 if (session->ref)
509 (*session->ref)(session);
510
f7faffa3
JC
511 /* Parse and check optional cookie */
512 if (session->peer_cookie_len > 0) {
513 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
514 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
515 "%s: cookie mismatch (%u/%u). Discarding.\n",
516 tunnel->name, tunnel->tunnel_id, session->session_id);
517 session->stats.rx_cookie_discards++;
518 goto discard;
519 }
520 ptr += session->peer_cookie_len;
521 }
522
fd558d18
JC
523 /* Handle the optional sequence numbers. Sequence numbers are
524 * in different places for L2TPv2 and L2TPv3.
525 *
526 * If we are the LAC, enable/disable sequence numbers under
527 * the control of the LNS. If no sequence numbers present but
528 * we were expecting them, discard frame.
529 */
530 ns = nr = 0;
531 L2TP_SKB_CB(skb)->has_seq = 0;
f7faffa3
JC
532 if (tunnel->version == L2TP_HDR_VER_2) {
533 if (hdrflags & L2TP_HDRFLAG_S) {
534 ns = ntohs(*(__be16 *) ptr);
535 ptr += 2;
536 nr = ntohs(*(__be16 *) ptr);
537 ptr += 2;
fd558d18 538
f7faffa3
JC
539 /* Store L2TP info in the skb */
540 L2TP_SKB_CB(skb)->ns = ns;
541 L2TP_SKB_CB(skb)->has_seq = 1;
fd558d18 542
f7faffa3
JC
543 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
544 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
545 session->name, ns, nr, session->nr);
546 }
547 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
548 u32 l2h = ntohl(*(__be32 *) ptr);
549
550 if (l2h & 0x40000000) {
551 ns = l2h & 0x00ffffff;
552
553 /* Store L2TP info in the skb */
554 L2TP_SKB_CB(skb)->ns = ns;
555 L2TP_SKB_CB(skb)->has_seq = 1;
556
557 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
558 "%s: recv data ns=%u, session nr=%u\n",
559 session->name, ns, session->nr);
560 }
fd558d18
JC
561 }
562
f7faffa3
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563 /* Advance past L2-specific header, if present */
564 ptr += session->l2specific_len;
565
fd558d18
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566 if (L2TP_SKB_CB(skb)->has_seq) {
567 /* Received a packet with sequence numbers. If we're the LNS,
568 * check if we sre sending sequence numbers and if not,
569 * configure it so.
570 */
571 if ((!session->lns_mode) && (!session->send_seq)) {
572 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
573 "%s: requested to enable seq numbers by LNS\n",
574 session->name);
575 session->send_seq = -1;
f7faffa3 576 l2tp_session_set_header_len(session, tunnel->version);
fd558d18
JC
577 }
578 } else {
579 /* No sequence numbers.
580 * If user has configured mandatory sequence numbers, discard.
581 */
582 if (session->recv_seq) {
583 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
584 "%s: recv data has no seq numbers when required. "
585 "Discarding\n", session->name);
586 session->stats.rx_seq_discards++;
587 goto discard;
588 }
589
590 /* If we're the LAC and we're sending sequence numbers, the
591 * LNS has requested that we no longer send sequence numbers.
592 * If we're the LNS and we're sending sequence numbers, the
593 * LAC is broken. Discard the frame.
594 */
595 if ((!session->lns_mode) && (session->send_seq)) {
596 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
597 "%s: requested to disable seq numbers by LNS\n",
598 session->name);
599 session->send_seq = 0;
f7faffa3 600 l2tp_session_set_header_len(session, tunnel->version);
fd558d18
JC
601 } else if (session->send_seq) {
602 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
603 "%s: recv data has no seq numbers when required. "
604 "Discarding\n", session->name);
605 session->stats.rx_seq_discards++;
606 goto discard;
607 }
608 }
609
f7faffa3
JC
610 /* Session data offset is handled differently for L2TPv2 and
611 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
612 * the header. For L2TPv3, the offset is negotiated using AVPs
613 * in the session setup control protocol.
614 */
615 if (tunnel->version == L2TP_HDR_VER_2) {
616 /* If offset bit set, skip it. */
617 if (hdrflags & L2TP_HDRFLAG_O) {
618 offset = ntohs(*(__be16 *)ptr);
619 ptr += 2 + offset;
620 }
621 } else
622 ptr += session->offset;
fd558d18
JC
623
624 offset = ptr - optr;
625 if (!pskb_may_pull(skb, offset))
626 goto discard;
627
628 __skb_pull(skb, offset);
629
630 /* If caller wants to process the payload before we queue the
631 * packet, do so now.
632 */
633 if (payload_hook)
634 if ((*payload_hook)(skb))
635 goto discard;
636
637 /* Prepare skb for adding to the session's reorder_q. Hold
638 * packets for max reorder_timeout or 1 second if not
639 * reordering.
640 */
641 L2TP_SKB_CB(skb)->length = length;
642 L2TP_SKB_CB(skb)->expires = jiffies +
643 (session->reorder_timeout ? session->reorder_timeout : HZ);
644
645 /* Add packet to the session's receive queue. Reordering is done here, if
646 * enabled. Saved L2TP protocol info is stored in skb->sb[].
647 */
648 if (L2TP_SKB_CB(skb)->has_seq) {
649 if (session->reorder_timeout != 0) {
650 /* Packet reordering enabled. Add skb to session's
651 * reorder queue, in order of ns.
652 */
653 l2tp_recv_queue_skb(session, skb);
654 } else {
655 /* Packet reordering disabled. Discard out-of-sequence
656 * packets
657 */
658 if (L2TP_SKB_CB(skb)->ns != session->nr) {
659 session->stats.rx_seq_discards++;
660 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
f7faffa3
JC
661 "%s: oos pkt %u len %d discarded, "
662 "waiting for %u, reorder_q_len=%d\n",
fd558d18
JC
663 session->name, L2TP_SKB_CB(skb)->ns,
664 L2TP_SKB_CB(skb)->length, session->nr,
665 skb_queue_len(&session->reorder_q));
666 goto discard;
667 }
668 skb_queue_tail(&session->reorder_q, skb);
669 }
670 } else {
671 /* No sequence numbers. Add the skb to the tail of the
672 * reorder queue. This ensures that it will be
673 * delivered after all previous sequenced skbs.
674 */
675 skb_queue_tail(&session->reorder_q, skb);
676 }
677
678 /* Try to dequeue as many skbs from reorder_q as we can. */
679 l2tp_recv_dequeue(session);
680
681 l2tp_session_dec_refcount(session);
682
f7faffa3 683 return;
fd558d18
JC
684
685discard:
686 session->stats.rx_errors++;
687 kfree_skb(skb);
688
689 if (session->deref)
690 (*session->deref)(session);
691
692 l2tp_session_dec_refcount(session);
f7faffa3
JC
693}
694EXPORT_SYMBOL(l2tp_recv_common);
695
696/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
697 * here. The skb is not on a list when we get here.
698 * Returns 0 if the packet was a data packet and was successfully passed on.
699 * Returns 1 if the packet was not a good data packet and could not be
700 * forwarded. All such packets are passed up to userspace to deal with.
701 */
702int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
703 int (*payload_hook)(struct sk_buff *skb))
704{
705 struct l2tp_session *session = NULL;
706 unsigned char *ptr, *optr;
707 u16 hdrflags;
708 u32 tunnel_id, session_id;
709 int offset;
710 u16 version;
711 int length;
712
713 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
714 goto discard_bad_csum;
715
716 /* UDP always verifies the packet length. */
717 __skb_pull(skb, sizeof(struct udphdr));
718
719 /* Short packet? */
720 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
721 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
722 "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
723 goto error;
724 }
725
726 /* Point to L2TP header */
727 optr = ptr = skb->data;
728
729 /* Trace packet contents, if enabled */
730 if (tunnel->debug & L2TP_MSG_DATA) {
731 length = min(32u, skb->len);
732 if (!pskb_may_pull(skb, length))
733 goto error;
734
735 printk(KERN_DEBUG "%s: recv: ", tunnel->name);
736
737 offset = 0;
738 do {
739 printk(" %02X", ptr[offset]);
740 } while (++offset < length);
741
742 printk("\n");
743 }
744
745 /* Get L2TP header flags */
746 hdrflags = ntohs(*(__be16 *) ptr);
747
748 /* Check protocol version */
749 version = hdrflags & L2TP_HDR_VER_MASK;
750 if (version != tunnel->version) {
751 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
752 "%s: recv protocol version mismatch: got %d expected %d\n",
753 tunnel->name, version, tunnel->version);
754 goto error;
755 }
756
757 /* Get length of L2TP packet */
758 length = skb->len;
759
760 /* If type is control packet, it is handled by userspace. */
761 if (hdrflags & L2TP_HDRFLAG_T) {
762 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
763 "%s: recv control packet, len=%d\n", tunnel->name, length);
764 goto error;
765 }
766
767 /* Skip flags */
768 ptr += 2;
769
770 if (tunnel->version == L2TP_HDR_VER_2) {
771 /* If length is present, skip it */
772 if (hdrflags & L2TP_HDRFLAG_L)
773 ptr += 2;
774
775 /* Extract tunnel and session ID */
776 tunnel_id = ntohs(*(__be16 *) ptr);
777 ptr += 2;
778 session_id = ntohs(*(__be16 *) ptr);
779 ptr += 2;
780 } else {
781 ptr += 2; /* skip reserved bits */
782 tunnel_id = tunnel->tunnel_id;
783 session_id = ntohl(*(__be32 *) ptr);
784 ptr += 4;
785 }
786
787 /* Find the session context */
788 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
309795f4 789 if (!session || !session->recv_skb) {
f7faffa3
JC
790 /* Not found? Pass to userspace to deal with */
791 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
792 "%s: no session found (%u/%u). Passing up.\n",
793 tunnel->name, tunnel_id, session_id);
794 goto error;
795 }
796
797 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
fd558d18
JC
798
799 return 0;
800
801discard_bad_csum:
802 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
803 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
804 tunnel->stats.rx_errors++;
805 kfree_skb(skb);
806
807 return 0;
808
809error:
810 /* Put UDP header back */
811 __skb_push(skb, sizeof(struct udphdr));
812
813 return 1;
814}
815EXPORT_SYMBOL_GPL(l2tp_udp_recv_core);
816
817/* UDP encapsulation receive handler. See net/ipv4/udp.c.
818 * Return codes:
819 * 0 : success.
820 * <0: error
821 * >0: skb should be passed up to userspace as UDP.
822 */
823int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
824{
825 struct l2tp_tunnel *tunnel;
826
827 tunnel = l2tp_sock_to_tunnel(sk);
828 if (tunnel == NULL)
829 goto pass_up;
830
831 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
832 "%s: received %d bytes\n", tunnel->name, skb->len);
833
834 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
835 goto pass_up_put;
836
837 sock_put(sk);
838 return 0;
839
840pass_up_put:
841 sock_put(sk);
842pass_up:
843 return 1;
844}
845EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
846
847/************************************************************************
848 * Transmit handling
849 ***********************************************************************/
850
851/* Build an L2TP header for the session into the buffer provided.
852 */
f7faffa3 853static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
fd558d18 854{
f7faffa3 855 struct l2tp_tunnel *tunnel = session->tunnel;
fd558d18 856 __be16 *bufp = buf;
f7faffa3 857 __be16 *optr = buf;
fd558d18
JC
858 u16 flags = L2TP_HDR_VER_2;
859 u32 tunnel_id = tunnel->peer_tunnel_id;
860 u32 session_id = session->peer_session_id;
861
862 if (session->send_seq)
863 flags |= L2TP_HDRFLAG_S;
864
865 /* Setup L2TP header. */
866 *bufp++ = htons(flags);
867 *bufp++ = htons(tunnel_id);
868 *bufp++ = htons(session_id);
869 if (session->send_seq) {
870 *bufp++ = htons(session->ns);
871 *bufp++ = 0;
872 session->ns++;
f7faffa3 873 session->ns &= 0xffff;
fd558d18 874 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
f7faffa3 875 "%s: updated ns to %u\n", session->name, session->ns);
fd558d18 876 }
f7faffa3
JC
877
878 return bufp - optr;
fd558d18
JC
879}
880
f7faffa3 881static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
fd558d18 882{
0d76751f 883 struct l2tp_tunnel *tunnel = session->tunnel;
f7faffa3
JC
884 char *bufp = buf;
885 char *optr = bufp;
f7faffa3 886
0d76751f
JC
887 /* Setup L2TP header. The header differs slightly for UDP and
888 * IP encapsulations. For UDP, there is 4 bytes of flags.
889 */
890 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
891 u16 flags = L2TP_HDR_VER_3;
892 *((__be16 *) bufp) = htons(flags);
893 bufp += 2;
894 *((__be16 *) bufp) = 0;
895 bufp += 2;
896 }
897
f7faffa3
JC
898 *((__be32 *) bufp) = htonl(session->peer_session_id);
899 bufp += 4;
900 if (session->cookie_len) {
901 memcpy(bufp, &session->cookie[0], session->cookie_len);
902 bufp += session->cookie_len;
903 }
904 if (session->l2specific_len) {
905 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
906 u32 l2h = 0;
907 if (session->send_seq) {
908 l2h = 0x40000000 | session->ns;
909 session->ns++;
910 session->ns &= 0xffffff;
911 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
912 "%s: updated ns to %u\n", session->name, session->ns);
913 }
914
915 *((__be32 *) bufp) = htonl(l2h);
916 }
917 bufp += session->l2specific_len;
918 }
919 if (session->offset)
920 bufp += session->offset;
fd558d18 921
f7faffa3 922 return bufp - optr;
fd558d18 923}
fd558d18
JC
924
925int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len)
926{
927 struct l2tp_tunnel *tunnel = session->tunnel;
928 unsigned int len = skb->len;
929 int error;
930
931 /* Debug */
932 if (session->send_seq)
933 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
f7faffa3 934 "%s: send %Zd bytes, ns=%u\n", session->name,
fd558d18
JC
935 data_len, session->ns - 1);
936 else
937 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
938 "%s: send %Zd bytes\n", session->name, data_len);
939
940 if (session->debug & L2TP_MSG_DATA) {
941 int i;
0d76751f
JC
942 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
943 unsigned char *datap = skb->data + uhlen;
fd558d18
JC
944
945 printk(KERN_DEBUG "%s: xmit:", session->name);
0d76751f 946 for (i = 0; i < (len - uhlen); i++) {
fd558d18
JC
947 printk(" %02X", *datap++);
948 if (i == 31) {
949 printk(" ...");
950 break;
951 }
952 }
953 printk("\n");
954 }
955
956 /* Queue the packet to IP for output */
4e15ed4d
SW
957 skb->local_df = 1;
958 error = ip_queue_xmit(skb);
fd558d18
JC
959
960 /* Update stats */
961 if (error >= 0) {
962 tunnel->stats.tx_packets++;
963 tunnel->stats.tx_bytes += len;
964 session->stats.tx_packets++;
965 session->stats.tx_bytes += len;
966 } else {
967 tunnel->stats.tx_errors++;
968 session->stats.tx_errors++;
969 }
970
971 return 0;
972}
973EXPORT_SYMBOL_GPL(l2tp_xmit_core);
974
975/* Automatically called when the skb is freed.
976 */
977static void l2tp_sock_wfree(struct sk_buff *skb)
978{
979 sock_put(skb->sk);
980}
981
982/* For data skbs that we transmit, we associate with the tunnel socket
983 * but don't do accounting.
984 */
985static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
986{
987 sock_hold(sk);
988 skb->sk = sk;
989 skb->destructor = l2tp_sock_wfree;
990}
991
992/* If caller requires the skb to have a ppp header, the header must be
993 * inserted in the skb data before calling this function.
994 */
995int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
996{
997 int data_len = skb->len;
0d76751f
JC
998 struct l2tp_tunnel *tunnel = session->tunnel;
999 struct sock *sk = tunnel->sock;
fd558d18 1000 struct udphdr *uh;
fd558d18
JC
1001 struct inet_sock *inet;
1002 __wsum csum;
1003 int old_headroom;
1004 int new_headroom;
1005 int headroom;
0d76751f
JC
1006 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1007 int udp_len;
fd558d18
JC
1008
1009 /* Check that there's enough headroom in the skb to insert IP,
1010 * UDP and L2TP headers. If not enough, expand it to
1011 * make room. Adjust truesize.
1012 */
1013 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
0d76751f 1014 uhlen + hdr_len;
fd558d18
JC
1015 old_headroom = skb_headroom(skb);
1016 if (skb_cow_head(skb, headroom))
1017 goto abort;
1018
1019 new_headroom = skb_headroom(skb);
1020 skb_orphan(skb);
1021 skb->truesize += new_headroom - old_headroom;
1022
1023 /* Setup L2TP header */
f7faffa3 1024 session->build_header(session, __skb_push(skb, hdr_len));
fd558d18 1025
0d76751f 1026 /* Reset skb netfilter state */
fd558d18
JC
1027 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1028 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1029 IPSKB_REROUTED);
1030 nf_reset(skb);
1031
1032 /* Get routing info from the tunnel socket */
1033 skb_dst_drop(skb);
1034 skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
fd558d18 1035
0d76751f
JC
1036 switch (tunnel->encap) {
1037 case L2TP_ENCAPTYPE_UDP:
1038 /* Setup UDP header */
1039 inet = inet_sk(sk);
1040 __skb_push(skb, sizeof(*uh));
1041 skb_reset_transport_header(skb);
1042 uh = udp_hdr(skb);
1043 uh->source = inet->inet_sport;
1044 uh->dest = inet->inet_dport;
1045 udp_len = uhlen + hdr_len + data_len;
1046 uh->len = htons(udp_len);
1047 uh->check = 0;
1048
1049 /* Calculate UDP checksum if configured to do so */
1050 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1051 skb->ip_summed = CHECKSUM_NONE;
1052 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1053 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1054 skb->ip_summed = CHECKSUM_COMPLETE;
1055 csum = skb_checksum(skb, 0, udp_len, 0);
1056 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1057 inet->inet_daddr,
1058 udp_len, IPPROTO_UDP, csum);
1059 if (uh->check == 0)
1060 uh->check = CSUM_MANGLED_0;
1061 } else {
1062 skb->ip_summed = CHECKSUM_PARTIAL;
1063 skb->csum_start = skb_transport_header(skb) - skb->head;
1064 skb->csum_offset = offsetof(struct udphdr, check);
1065 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1066 inet->inet_daddr,
1067 udp_len, IPPROTO_UDP, 0);
1068 }
1069 break;
1070
1071 case L2TP_ENCAPTYPE_IP:
1072 break;
fd558d18
JC
1073 }
1074
0d76751f
JC
1075 l2tp_skb_set_owner_w(skb, sk);
1076
fd558d18
JC
1077 l2tp_xmit_core(session, skb, data_len);
1078
1079abort:
1080 return 0;
1081}
1082EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1083
1084/*****************************************************************************
1085 * Tinnel and session create/destroy.
1086 *****************************************************************************/
1087
1088/* Tunnel socket destruct hook.
1089 * The tunnel context is deleted only when all session sockets have been
1090 * closed.
1091 */
1092void l2tp_tunnel_destruct(struct sock *sk)
1093{
1094 struct l2tp_tunnel *tunnel;
1095
1096 tunnel = sk->sk_user_data;
1097 if (tunnel == NULL)
1098 goto end;
1099
1100 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1101 "%s: closing...\n", tunnel->name);
1102
1103 /* Close all sessions */
1104 l2tp_tunnel_closeall(tunnel);
1105
0d76751f
JC
1106 switch (tunnel->encap) {
1107 case L2TP_ENCAPTYPE_UDP:
1108 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1109 (udp_sk(sk))->encap_type = 0;
1110 (udp_sk(sk))->encap_rcv = NULL;
1111 break;
1112 case L2TP_ENCAPTYPE_IP:
1113 break;
1114 }
fd558d18
JC
1115
1116 /* Remove hooks into tunnel socket */
1117 tunnel->sock = NULL;
1118 sk->sk_destruct = tunnel->old_sk_destruct;
1119 sk->sk_user_data = NULL;
1120
1121 /* Call the original destructor */
1122 if (sk->sk_destruct)
1123 (*sk->sk_destruct)(sk);
1124
1125 /* We're finished with the socket */
1126 l2tp_tunnel_dec_refcount(tunnel);
1127
1128end:
1129 return;
1130}
1131EXPORT_SYMBOL(l2tp_tunnel_destruct);
1132
1133/* When the tunnel is closed, all the attached sessions need to go too.
1134 */
1135void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1136{
1137 int hash;
1138 struct hlist_node *walk;
1139 struct hlist_node *tmp;
1140 struct l2tp_session *session;
1141
1142 BUG_ON(tunnel == NULL);
1143
1144 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1145 "%s: closing all sessions...\n", tunnel->name);
1146
1147 write_lock_bh(&tunnel->hlist_lock);
1148 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1149again:
1150 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1151 session = hlist_entry(walk, struct l2tp_session, hlist);
1152
1153 PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
1154 "%s: closing session\n", session->name);
1155
1156 hlist_del_init(&session->hlist);
1157
1158 /* Since we should hold the sock lock while
1159 * doing any unbinding, we need to release the
1160 * lock we're holding before taking that lock.
1161 * Hold a reference to the sock so it doesn't
1162 * disappear as we're jumping between locks.
1163 */
1164 if (session->ref != NULL)
1165 (*session->ref)(session);
1166
1167 write_unlock_bh(&tunnel->hlist_lock);
1168
f7faffa3
JC
1169 if (tunnel->version != L2TP_HDR_VER_2) {
1170 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1171
e02d494d
JC
1172 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1173 hlist_del_init_rcu(&session->global_hlist);
1174 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1175 synchronize_rcu();
f7faffa3
JC
1176 }
1177
fd558d18
JC
1178 if (session->session_close != NULL)
1179 (*session->session_close)(session);
1180
1181 if (session->deref != NULL)
1182 (*session->deref)(session);
1183
1184 write_lock_bh(&tunnel->hlist_lock);
1185
1186 /* Now restart from the beginning of this hash
1187 * chain. We always remove a session from the
1188 * list so we are guaranteed to make forward
1189 * progress.
1190 */
1191 goto again;
1192 }
1193 }
1194 write_unlock_bh(&tunnel->hlist_lock);
1195}
1196EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1197
1198/* Really kill the tunnel.
1199 * Come here only when all sessions have been cleared from the tunnel.
1200 */
1201void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1202{
1203 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1204
1205 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1206 BUG_ON(tunnel->sock != NULL);
1207
1208 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1209 "%s: free...\n", tunnel->name);
1210
1211 /* Remove from tunnel list */
e02d494d
JC
1212 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1213 list_del_rcu(&tunnel->list);
1214 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1215 synchronize_rcu();
fd558d18
JC
1216
1217 atomic_dec(&l2tp_tunnel_count);
1218 kfree(tunnel);
1219}
1220EXPORT_SYMBOL_GPL(l2tp_tunnel_free);
1221
789a4a2c
JC
1222/* Create a socket for the tunnel, if one isn't set up by
1223 * userspace. This is used for static tunnels where there is no
1224 * managing L2TP daemon.
1225 */
1226static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1227{
1228 int err = -EINVAL;
1229 struct sockaddr_in udp_addr;
1230 struct sockaddr_l2tpip ip_addr;
7bddd0db 1231 struct socket *sock = NULL;
789a4a2c
JC
1232
1233 switch (cfg->encap) {
1234 case L2TP_ENCAPTYPE_UDP:
1235 err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1236 if (err < 0)
1237 goto out;
1238
1239 sock = *sockp;
1240
1241 memset(&udp_addr, 0, sizeof(udp_addr));
1242 udp_addr.sin_family = AF_INET;
1243 udp_addr.sin_addr = cfg->local_ip;
1244 udp_addr.sin_port = htons(cfg->local_udp_port);
1245 err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr));
1246 if (err < 0)
1247 goto out;
1248
1249 udp_addr.sin_family = AF_INET;
1250 udp_addr.sin_addr = cfg->peer_ip;
1251 udp_addr.sin_port = htons(cfg->peer_udp_port);
1252 err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0);
1253 if (err < 0)
1254 goto out;
1255
1256 if (!cfg->use_udp_checksums)
1257 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1258
1259 break;
1260
1261 case L2TP_ENCAPTYPE_IP:
1262 err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP, sockp);
1263 if (err < 0)
1264 goto out;
1265
1266 sock = *sockp;
1267
1268 memset(&ip_addr, 0, sizeof(ip_addr));
1269 ip_addr.l2tp_family = AF_INET;
1270 ip_addr.l2tp_addr = cfg->local_ip;
1271 ip_addr.l2tp_conn_id = tunnel_id;
1272 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr));
1273 if (err < 0)
1274 goto out;
1275
1276 ip_addr.l2tp_family = AF_INET;
1277 ip_addr.l2tp_addr = cfg->peer_ip;
1278 ip_addr.l2tp_conn_id = peer_tunnel_id;
1279 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr), 0);
1280 if (err < 0)
1281 goto out;
1282
1283 break;
1284
1285 default:
1286 goto out;
1287 }
1288
1289out:
1290 if ((err < 0) && sock) {
1291 sock_release(sock);
1292 *sockp = NULL;
1293 }
1294
1295 return err;
1296}
1297
fd558d18
JC
1298int 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)
1299{
1300 struct l2tp_tunnel *tunnel = NULL;
1301 int err;
1302 struct socket *sock = NULL;
1303 struct sock *sk = NULL;
1304 struct l2tp_net *pn;
0d76751f 1305 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
fd558d18
JC
1306
1307 /* Get the tunnel socket from the fd, which was opened by
789a4a2c
JC
1308 * the userspace L2TP daemon. If not specified, create a
1309 * kernel socket.
fd558d18 1310 */
789a4a2c
JC
1311 if (fd < 0) {
1312 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1313 if (err < 0)
1314 goto err;
1315 } else {
1316 err = -EBADF;
1317 sock = sockfd_lookup(fd, &err);
1318 if (!sock) {
1319 printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1320 tunnel_id, fd, err);
1321 goto err;
1322 }
fd558d18
JC
1323 }
1324
1325 sk = sock->sk;
1326
0d76751f
JC
1327 if (cfg != NULL)
1328 encap = cfg->encap;
1329
fd558d18 1330 /* Quick sanity checks */
0d76751f
JC
1331 switch (encap) {
1332 case L2TP_ENCAPTYPE_UDP:
1333 err = -EPROTONOSUPPORT;
1334 if (sk->sk_protocol != IPPROTO_UDP) {
1335 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1336 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1337 goto err;
1338 }
1339 break;
1340 case L2TP_ENCAPTYPE_IP:
1341 err = -EPROTONOSUPPORT;
1342 if (sk->sk_protocol != IPPROTO_L2TP) {
1343 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1344 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1345 goto err;
1346 }
1347 break;
fd558d18
JC
1348 }
1349
1350 /* Check if this socket has already been prepped */
1351 tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1352 if (tunnel != NULL) {
1353 /* This socket has already been prepped */
1354 err = -EBUSY;
1355 goto err;
1356 }
1357
fd558d18
JC
1358 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1359 if (tunnel == NULL) {
1360 err = -ENOMEM;
1361 goto err;
1362 }
1363
1364 tunnel->version = version;
1365 tunnel->tunnel_id = tunnel_id;
1366 tunnel->peer_tunnel_id = peer_tunnel_id;
1367 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1368
1369 tunnel->magic = L2TP_TUNNEL_MAGIC;
1370 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1371 rwlock_init(&tunnel->hlist_lock);
1372
1373 /* The net we belong to */
1374 tunnel->l2tp_net = net;
1375 pn = l2tp_pernet(net);
1376
0d76751f 1377 if (cfg != NULL)
fd558d18
JC
1378 tunnel->debug = cfg->debug;
1379
1380 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
0d76751f
JC
1381 tunnel->encap = encap;
1382 if (encap == L2TP_ENCAPTYPE_UDP) {
1383 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1384 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1385 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1386 }
fd558d18
JC
1387
1388 sk->sk_user_data = tunnel;
1389
1390 /* Hook on the tunnel socket destructor so that we can cleanup
1391 * if the tunnel socket goes away.
1392 */
1393 tunnel->old_sk_destruct = sk->sk_destruct;
1394 sk->sk_destruct = &l2tp_tunnel_destruct;
1395 tunnel->sock = sk;
1396 sk->sk_allocation = GFP_ATOMIC;
1397
1398 /* Add tunnel to our list */
1399 INIT_LIST_HEAD(&tunnel->list);
e02d494d
JC
1400 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1401 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1402 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1403 synchronize_rcu();
fd558d18
JC
1404 atomic_inc(&l2tp_tunnel_count);
1405
1406 /* Bump the reference count. The tunnel context is deleted
1407 * only when this drops to zero.
1408 */
1409 l2tp_tunnel_inc_refcount(tunnel);
1410
1411 err = 0;
1412err:
1413 if (tunnelp)
1414 *tunnelp = tunnel;
1415
789a4a2c
JC
1416 /* If tunnel's socket was created by the kernel, it doesn't
1417 * have a file.
1418 */
1419 if (sock && sock->file)
fd558d18
JC
1420 sockfd_put(sock);
1421
1422 return err;
1423}
1424EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1425
309795f4
JC
1426/* This function is used by the netlink TUNNEL_DELETE command.
1427 */
1428int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1429{
1430 int err = 0;
789a4a2c 1431 struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
309795f4
JC
1432
1433 /* Force the tunnel socket to close. This will eventually
1434 * cause the tunnel to be deleted via the normal socket close
1435 * mechanisms when userspace closes the tunnel socket.
1436 */
789a4a2c
JC
1437 if (sock != NULL) {
1438 err = inet_shutdown(sock, 2);
1439
1440 /* If the tunnel's socket was created by the kernel,
1441 * close the socket here since the socket was not
1442 * created by userspace.
1443 */
1444 if (sock->file == NULL)
1445 err = inet_release(sock);
1446 }
309795f4
JC
1447
1448 return err;
1449}
1450EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1451
fd558d18
JC
1452/* Really kill the session.
1453 */
1454void l2tp_session_free(struct l2tp_session *session)
1455{
1456 struct l2tp_tunnel *tunnel;
1457
1458 BUG_ON(atomic_read(&session->ref_count) != 0);
1459
1460 tunnel = session->tunnel;
1461 if (tunnel != NULL) {
1462 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1463
1464 /* Delete the session from the hash */
1465 write_lock_bh(&tunnel->hlist_lock);
1466 hlist_del_init(&session->hlist);
1467 write_unlock_bh(&tunnel->hlist_lock);
1468
f7faffa3
JC
1469 /* Unlink from the global hash if not L2TPv2 */
1470 if (tunnel->version != L2TP_HDR_VER_2) {
1471 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1472
e02d494d
JC
1473 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1474 hlist_del_init_rcu(&session->global_hlist);
1475 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1476 synchronize_rcu();
f7faffa3
JC
1477 }
1478
fd558d18
JC
1479 if (session->session_id != 0)
1480 atomic_dec(&l2tp_session_count);
1481
1482 sock_put(tunnel->sock);
1483
1484 /* This will delete the tunnel context if this
1485 * is the last session on the tunnel.
1486 */
1487 session->tunnel = NULL;
1488 l2tp_tunnel_dec_refcount(tunnel);
1489 }
1490
1491 kfree(session);
1492
1493 return;
1494}
1495EXPORT_SYMBOL_GPL(l2tp_session_free);
1496
309795f4
JC
1497/* This function is used by the netlink SESSION_DELETE command and by
1498 pseudowire modules.
1499 */
1500int l2tp_session_delete(struct l2tp_session *session)
1501{
1502 if (session->session_close != NULL)
1503 (*session->session_close)(session);
1504
1505 l2tp_session_dec_refcount(session);
1506
1507 return 0;
1508}
1509EXPORT_SYMBOL_GPL(l2tp_session_delete);
1510
1511
f7faffa3
JC
1512/* We come here whenever a session's send_seq, cookie_len or
1513 * l2specific_len parameters are set.
1514 */
1515void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1516{
1517 if (version == L2TP_HDR_VER_2) {
1518 session->hdr_len = 6;
1519 if (session->send_seq)
1520 session->hdr_len += 4;
1521 } else {
0d76751f
JC
1522 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1523 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1524 session->hdr_len += 4;
f7faffa3
JC
1525 }
1526
1527}
1528EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1529
fd558d18
JC
1530struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
1531{
1532 struct l2tp_session *session;
1533
1534 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1535 if (session != NULL) {
1536 session->magic = L2TP_SESSION_MAGIC;
1537 session->tunnel = tunnel;
1538
1539 session->session_id = session_id;
1540 session->peer_session_id = peer_session_id;
f7faffa3 1541 session->nr = 1;
fd558d18
JC
1542
1543 sprintf(&session->name[0], "sess %u/%u",
1544 tunnel->tunnel_id, session->session_id);
1545
1546 skb_queue_head_init(&session->reorder_q);
1547
1548 INIT_HLIST_NODE(&session->hlist);
f7faffa3 1549 INIT_HLIST_NODE(&session->global_hlist);
fd558d18
JC
1550
1551 /* Inherit debug options from tunnel */
1552 session->debug = tunnel->debug;
1553
1554 if (cfg) {
f7faffa3 1555 session->pwtype = cfg->pw_type;
fd558d18 1556 session->debug = cfg->debug;
fd558d18
JC
1557 session->mtu = cfg->mtu;
1558 session->mru = cfg->mru;
1559 session->send_seq = cfg->send_seq;
1560 session->recv_seq = cfg->recv_seq;
1561 session->lns_mode = cfg->lns_mode;
f7faffa3
JC
1562 session->reorder_timeout = cfg->reorder_timeout;
1563 session->offset = cfg->offset;
1564 session->l2specific_type = cfg->l2specific_type;
1565 session->l2specific_len = cfg->l2specific_len;
1566 session->cookie_len = cfg->cookie_len;
1567 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1568 session->peer_cookie_len = cfg->peer_cookie_len;
1569 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
fd558d18
JC
1570 }
1571
f7faffa3
JC
1572 if (tunnel->version == L2TP_HDR_VER_2)
1573 session->build_header = l2tp_build_l2tpv2_header;
1574 else
1575 session->build_header = l2tp_build_l2tpv3_header;
1576
1577 l2tp_session_set_header_len(session, tunnel->version);
1578
fd558d18
JC
1579 /* Bump the reference count. The session context is deleted
1580 * only when this drops to zero.
1581 */
1582 l2tp_session_inc_refcount(session);
1583 l2tp_tunnel_inc_refcount(tunnel);
1584
1585 /* Ensure tunnel socket isn't deleted */
1586 sock_hold(tunnel->sock);
1587
1588 /* Add session to the tunnel's hash list */
1589 write_lock_bh(&tunnel->hlist_lock);
1590 hlist_add_head(&session->hlist,
1591 l2tp_session_id_hash(tunnel, session_id));
1592 write_unlock_bh(&tunnel->hlist_lock);
1593
f7faffa3
JC
1594 /* And to the global session list if L2TPv3 */
1595 if (tunnel->version != L2TP_HDR_VER_2) {
1596 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1597
e02d494d
JC
1598 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1599 hlist_add_head_rcu(&session->global_hlist,
1600 l2tp_session_id_hash_2(pn, session_id));
1601 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1602 synchronize_rcu();
f7faffa3
JC
1603 }
1604
fd558d18
JC
1605 /* Ignore management session in session count value */
1606 if (session->session_id != 0)
1607 atomic_inc(&l2tp_session_count);
1608 }
1609
1610 return session;
1611}
1612EXPORT_SYMBOL_GPL(l2tp_session_create);
1613
1614/*****************************************************************************
1615 * Init and cleanup
1616 *****************************************************************************/
1617
1618static __net_init int l2tp_init_net(struct net *net)
1619{
1620 struct l2tp_net *pn;
1621 int err;
f7faffa3 1622 int hash;
fd558d18
JC
1623
1624 pn = kzalloc(sizeof(*pn), GFP_KERNEL);
1625 if (!pn)
1626 return -ENOMEM;
1627
1628 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
e02d494d 1629 spin_lock_init(&pn->l2tp_tunnel_list_lock);
fd558d18 1630
f7faffa3
JC
1631 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1632 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1633
e02d494d 1634 spin_lock_init(&pn->l2tp_session_hlist_lock);
f7faffa3 1635
fd558d18
JC
1636 err = net_assign_generic(net, l2tp_net_id, pn);
1637 if (err)
1638 goto out;
1639
1640 return 0;
1641
1642out:
1643 kfree(pn);
1644 return err;
1645}
1646
1647static __net_exit void l2tp_exit_net(struct net *net)
1648{
1649 struct l2tp_net *pn;
1650
1651 pn = net_generic(net, l2tp_net_id);
1652 /*
1653 * if someone has cached our net then
1654 * further net_generic call will return NULL
1655 */
1656 net_assign_generic(net, l2tp_net_id, NULL);
1657 kfree(pn);
1658}
1659
1660static struct pernet_operations l2tp_net_ops = {
1661 .init = l2tp_init_net,
1662 .exit = l2tp_exit_net,
1663 .id = &l2tp_net_id,
1664 .size = sizeof(struct l2tp_net),
1665};
1666
1667static int __init l2tp_init(void)
1668{
1669 int rc = 0;
1670
1671 rc = register_pernet_device(&l2tp_net_ops);
1672 if (rc)
1673 goto out;
1674
1675 printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);
1676
1677out:
1678 return rc;
1679}
1680
1681static void __exit l2tp_exit(void)
1682{
1683 unregister_pernet_device(&l2tp_net_ops);
1684}
1685
1686module_init(l2tp_init);
1687module_exit(l2tp_exit);
1688
1689MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1690MODULE_DESCRIPTION("L2TP core");
1691MODULE_LICENSE("GPL");
1692MODULE_VERSION(L2TP_DRV_VERSION);
1693