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 */
93 struct l2tp_skb_cb {
94 u32 ns;
95 u16 has_seq;
96 u16 length;
97 unsigned long expires;
98 };
99
100 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
101
102 static atomic_t l2tp_tunnel_count;
103 static atomic_t l2tp_session_count;
104
105 /* per-net private data for this module */
106 static unsigned int l2tp_net_id;
107 struct 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
114 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
115 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
116 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
117
l2tp_pernet(struct net * net)118 static 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 */
l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel * tunnel)129 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
130 {
131 atomic_inc(&tunnel->ref_count);
132 }
133
l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel * tunnel)134 static 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 */
158 static inline struct hlist_head *
l2tp_session_id_hash_2(struct l2tp_net * pn,u32 session_id)159 l2tp_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 */
l2tp_session_find_2(struct net * net,u32 session_id)167 static 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 */
193 static inline struct hlist_head *
l2tp_session_id_hash(struct l2tp_tunnel * tunnel,u32 session_id)194 l2tp_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 */
l2tp_session_find(struct net * net,struct l2tp_tunnel * tunnel,u32 session_id)201 struct 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 }
226 EXPORT_SYMBOL_GPL(l2tp_session_find);
227
l2tp_session_find_nth(struct l2tp_tunnel * tunnel,int nth)228 struct 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 }
249 EXPORT_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 */
l2tp_session_find_by_ifname(struct net * net,char * ifname)254 struct 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 }
275 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
276
277 /* Lookup a tunnel by id
278 */
l2tp_tunnel_find(struct net * net,u32 tunnel_id)279 struct 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 }
295 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
296
l2tp_tunnel_find_nth(struct net * net,int nth)297 struct 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 }
315 EXPORT_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 */
l2tp_recv_queue_skb(struct l2tp_session * session,struct sk_buff * skb)324 static 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
345 out:
346 spin_unlock_bh(&session->reorder_q.lock);
347 }
348
349 /* Dequeue a single skb.
350 */
l2tp_recv_dequeue_skb(struct l2tp_session * session,struct sk_buff * skb)351 static 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 */
l2tp_recv_dequeue(struct l2tp_session * session)391 static 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 start:
401 spin_lock_bh(&session->reorder_q.lock);
402 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
403 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
404 session->stats.rx_seq_discards++;
405 session->stats.rx_errors++;
406 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
407 "%s: oos pkt %u len %d discarded (too old), "
408 "waiting for %u, reorder_q_len=%d\n",
409 session->name, L2TP_SKB_CB(skb)->ns,
410 L2TP_SKB_CB(skb)->length, session->nr,
411 skb_queue_len(&session->reorder_q));
412 __skb_unlink(skb, &session->reorder_q);
413 kfree_skb(skb);
414 if (session->deref)
415 (*session->deref)(session);
416 continue;
417 }
418
419 if (L2TP_SKB_CB(skb)->has_seq) {
420 if (L2TP_SKB_CB(skb)->ns != session->nr) {
421 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
422 "%s: holding oos pkt %u len %d, "
423 "waiting for %u, reorder_q_len=%d\n",
424 session->name, L2TP_SKB_CB(skb)->ns,
425 L2TP_SKB_CB(skb)->length, session->nr,
426 skb_queue_len(&session->reorder_q));
427 goto out;
428 }
429 }
430 __skb_unlink(skb, &session->reorder_q);
431
432 /* Process the skb. We release the queue lock while we
433 * do so to let other contexts process the queue.
434 */
435 spin_unlock_bh(&session->reorder_q.lock);
436 l2tp_recv_dequeue_skb(session, skb);
437 goto start;
438 }
439
440 out:
441 spin_unlock_bh(&session->reorder_q.lock);
442 }
443
l2tp_verify_udp_checksum(struct sock * sk,struct sk_buff * skb)444 static inline int l2tp_verify_udp_checksum(struct sock *sk,
445 struct sk_buff *skb)
446 {
447 struct udphdr *uh = udp_hdr(skb);
448 u16 ulen = ntohs(uh->len);
449 struct inet_sock *inet;
450 __wsum psum;
451
452 if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
453 return 0;
454
455 inet = inet_sk(sk);
456 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
457 IPPROTO_UDP, 0);
458
459 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
460 !csum_fold(csum_add(psum, skb->csum)))
461 return 0;
462
463 skb->csum = psum;
464
465 return __skb_checksum_complete(skb);
466 }
467
468 /* Do receive processing of L2TP data frames. We handle both L2TPv2
469 * and L2TPv3 data frames here.
470 *
471 * L2TPv2 Data Message Header
472 *
473 * 0 1 2 3
474 * 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
475 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
476 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
477 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
478 * | Tunnel ID | Session ID |
479 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
480 * | Ns (opt) | Nr (opt) |
481 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
482 * | Offset Size (opt) | Offset pad... (opt)
483 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
484 *
485 * Data frames are marked by T=0. All other fields are the same as
486 * those in L2TP control frames.
487 *
488 * L2TPv3 Data Message Header
489 *
490 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
491 * | L2TP Session Header |
492 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
493 * | L2-Specific Sublayer |
494 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
495 * | Tunnel Payload ...
496 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
497 *
498 * L2TPv3 Session Header Over IP
499 *
500 * 0 1 2 3
501 * 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
502 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
503 * | Session ID |
504 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
505 * | Cookie (optional, maximum 64 bits)...
506 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
507 * |
508 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
509 *
510 * L2TPv3 L2-Specific Sublayer Format
511 *
512 * 0 1 2 3
513 * 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
514 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
515 * |x|S|x|x|x|x|x|x| Sequence Number |
516 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
517 *
518 * Cookie value, sublayer format and offset (pad) are negotiated with
519 * the peer when the session is set up. Unlike L2TPv2, we do not need
520 * to parse the packet header to determine if optional fields are
521 * present.
522 *
523 * Caller must already have parsed the frame and determined that it is
524 * a data (not control) frame before coming here. Fields up to the
525 * session-id have already been parsed and ptr points to the data
526 * after the session-id.
527 */
l2tp_recv_common(struct l2tp_session * session,struct sk_buff * skb,unsigned char * ptr,unsigned char * optr,u16 hdrflags,int length,int (* payload_hook)(struct sk_buff * skb))528 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
529 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
530 int length, int (*payload_hook)(struct sk_buff *skb))
531 {
532 struct l2tp_tunnel *tunnel = session->tunnel;
533 int offset;
534 u32 ns, nr;
535
536 /* The ref count is increased since we now hold a pointer to
537 * the session. Take care to decrement the refcnt when exiting
538 * this function from now on...
539 */
540 l2tp_session_inc_refcount(session);
541 if (session->ref)
542 (*session->ref)(session);
543
544 /* Parse and check optional cookie */
545 if (session->peer_cookie_len > 0) {
546 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
547 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
548 "%s: cookie mismatch (%u/%u). Discarding.\n",
549 tunnel->name, tunnel->tunnel_id, session->session_id);
550 session->stats.rx_cookie_discards++;
551 goto discard;
552 }
553 ptr += session->peer_cookie_len;
554 }
555
556 /* Handle the optional sequence numbers. Sequence numbers are
557 * in different places for L2TPv2 and L2TPv3.
558 *
559 * If we are the LAC, enable/disable sequence numbers under
560 * the control of the LNS. If no sequence numbers present but
561 * we were expecting them, discard frame.
562 */
563 ns = nr = 0;
564 L2TP_SKB_CB(skb)->has_seq = 0;
565 if (tunnel->version == L2TP_HDR_VER_2) {
566 if (hdrflags & L2TP_HDRFLAG_S) {
567 ns = ntohs(*(__be16 *) ptr);
568 ptr += 2;
569 nr = ntohs(*(__be16 *) ptr);
570 ptr += 2;
571
572 /* Store L2TP info in the skb */
573 L2TP_SKB_CB(skb)->ns = ns;
574 L2TP_SKB_CB(skb)->has_seq = 1;
575
576 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
577 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
578 session->name, ns, nr, session->nr);
579 }
580 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
581 u32 l2h = ntohl(*(__be32 *) ptr);
582
583 if (l2h & 0x40000000) {
584 ns = l2h & 0x00ffffff;
585
586 /* Store L2TP info in the skb */
587 L2TP_SKB_CB(skb)->ns = ns;
588 L2TP_SKB_CB(skb)->has_seq = 1;
589
590 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
591 "%s: recv data ns=%u, session nr=%u\n",
592 session->name, ns, session->nr);
593 }
594 }
595
596 /* Advance past L2-specific header, if present */
597 ptr += session->l2specific_len;
598
599 if (L2TP_SKB_CB(skb)->has_seq) {
600 /* Received a packet with sequence numbers. If we're the LNS,
601 * check if we sre sending sequence numbers and if not,
602 * configure it so.
603 */
604 if ((!session->lns_mode) && (!session->send_seq)) {
605 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
606 "%s: requested to enable seq numbers by LNS\n",
607 session->name);
608 session->send_seq = -1;
609 l2tp_session_set_header_len(session, tunnel->version);
610 }
611 } else {
612 /* No sequence numbers.
613 * If user has configured mandatory sequence numbers, discard.
614 */
615 if (session->recv_seq) {
616 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
617 "%s: recv data has no seq numbers when required. "
618 "Discarding\n", session->name);
619 session->stats.rx_seq_discards++;
620 goto discard;
621 }
622
623 /* If we're the LAC and we're sending sequence numbers, the
624 * LNS has requested that we no longer send sequence numbers.
625 * If we're the LNS and we're sending sequence numbers, the
626 * LAC is broken. Discard the frame.
627 */
628 if ((!session->lns_mode) && (session->send_seq)) {
629 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
630 "%s: requested to disable seq numbers by LNS\n",
631 session->name);
632 session->send_seq = 0;
633 l2tp_session_set_header_len(session, tunnel->version);
634 } else if (session->send_seq) {
635 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
636 "%s: recv data has no seq numbers when required. "
637 "Discarding\n", session->name);
638 session->stats.rx_seq_discards++;
639 goto discard;
640 }
641 }
642
643 /* Session data offset is handled differently for L2TPv2 and
644 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
645 * the header. For L2TPv3, the offset is negotiated using AVPs
646 * in the session setup control protocol.
647 */
648 if (tunnel->version == L2TP_HDR_VER_2) {
649 /* If offset bit set, skip it. */
650 if (hdrflags & L2TP_HDRFLAG_O) {
651 offset = ntohs(*(__be16 *)ptr);
652 ptr += 2 + offset;
653 }
654 } else
655 ptr += session->offset;
656
657 offset = ptr - optr;
658 if (!pskb_may_pull(skb, offset))
659 goto discard;
660
661 __skb_pull(skb, offset);
662
663 /* If caller wants to process the payload before we queue the
664 * packet, do so now.
665 */
666 if (payload_hook)
667 if ((*payload_hook)(skb))
668 goto discard;
669
670 /* Prepare skb for adding to the session's reorder_q. Hold
671 * packets for max reorder_timeout or 1 second if not
672 * reordering.
673 */
674 L2TP_SKB_CB(skb)->length = length;
675 L2TP_SKB_CB(skb)->expires = jiffies +
676 (session->reorder_timeout ? session->reorder_timeout : HZ);
677
678 /* Add packet to the session's receive queue. Reordering is done here, if
679 * enabled. Saved L2TP protocol info is stored in skb->sb[].
680 */
681 if (L2TP_SKB_CB(skb)->has_seq) {
682 if (session->reorder_timeout != 0) {
683 /* Packet reordering enabled. Add skb to session's
684 * reorder queue, in order of ns.
685 */
686 l2tp_recv_queue_skb(session, skb);
687 } else {
688 /* Packet reordering disabled. Discard out-of-sequence
689 * packets
690 */
691 if (L2TP_SKB_CB(skb)->ns != session->nr) {
692 session->stats.rx_seq_discards++;
693 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
694 "%s: oos pkt %u len %d discarded, "
695 "waiting for %u, reorder_q_len=%d\n",
696 session->name, L2TP_SKB_CB(skb)->ns,
697 L2TP_SKB_CB(skb)->length, session->nr,
698 skb_queue_len(&session->reorder_q));
699 goto discard;
700 }
701 skb_queue_tail(&session->reorder_q, skb);
702 }
703 } else {
704 /* No sequence numbers. Add the skb to the tail of the
705 * reorder queue. This ensures that it will be
706 * delivered after all previous sequenced skbs.
707 */
708 skb_queue_tail(&session->reorder_q, skb);
709 }
710
711 /* Try to dequeue as many skbs from reorder_q as we can. */
712 l2tp_recv_dequeue(session);
713
714 l2tp_session_dec_refcount(session);
715
716 return;
717
718 discard:
719 session->stats.rx_errors++;
720 kfree_skb(skb);
721
722 if (session->deref)
723 (*session->deref)(session);
724
725 l2tp_session_dec_refcount(session);
726 }
727 EXPORT_SYMBOL(l2tp_recv_common);
728
729 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
730 * here. The skb is not on a list when we get here.
731 * Returns 0 if the packet was a data packet and was successfully passed on.
732 * Returns 1 if the packet was not a good data packet and could not be
733 * forwarded. All such packets are passed up to userspace to deal with.
734 */
l2tp_udp_recv_core(struct l2tp_tunnel * tunnel,struct sk_buff * skb,int (* payload_hook)(struct sk_buff * skb))735 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
736 int (*payload_hook)(struct sk_buff *skb))
737 {
738 struct l2tp_session *session = NULL;
739 unsigned char *ptr, *optr;
740 u16 hdrflags;
741 u32 tunnel_id, session_id;
742 int offset;
743 u16 version;
744 int length;
745
746 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
747 goto discard_bad_csum;
748
749 /* UDP always verifies the packet length. */
750 __skb_pull(skb, sizeof(struct udphdr));
751
752 /* Short packet? */
753 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
754 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
755 "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
756 goto error;
757 }
758
759 /* Trace packet contents, if enabled */
760 if (tunnel->debug & L2TP_MSG_DATA) {
761 length = min(32u, skb->len);
762 if (!pskb_may_pull(skb, length))
763 goto error;
764
765 printk(KERN_DEBUG "%s: recv: ", tunnel->name);
766
767 offset = 0;
768 do {
769 printk(" %02X", skb->data[offset]);
770 } while (++offset < length);
771
772 printk("\n");
773 }
774
775 /* Point to L2TP header */
776 optr = ptr = skb->data;
777
778 /* Get L2TP header flags */
779 hdrflags = ntohs(*(__be16 *) ptr);
780
781 /* Check protocol version */
782 version = hdrflags & L2TP_HDR_VER_MASK;
783 if (version != tunnel->version) {
784 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
785 "%s: recv protocol version mismatch: got %d expected %d\n",
786 tunnel->name, version, tunnel->version);
787 goto error;
788 }
789
790 /* Get length of L2TP packet */
791 length = skb->len;
792
793 /* If type is control packet, it is handled by userspace. */
794 if (hdrflags & L2TP_HDRFLAG_T) {
795 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
796 "%s: recv control packet, len=%d\n", tunnel->name, length);
797 goto error;
798 }
799
800 /* Skip flags */
801 ptr += 2;
802
803 if (tunnel->version == L2TP_HDR_VER_2) {
804 /* If length is present, skip it */
805 if (hdrflags & L2TP_HDRFLAG_L)
806 ptr += 2;
807
808 /* Extract tunnel and session ID */
809 tunnel_id = ntohs(*(__be16 *) ptr);
810 ptr += 2;
811 session_id = ntohs(*(__be16 *) ptr);
812 ptr += 2;
813 } else {
814 ptr += 2; /* skip reserved bits */
815 tunnel_id = tunnel->tunnel_id;
816 session_id = ntohl(*(__be32 *) ptr);
817 ptr += 4;
818 }
819
820 /* Find the session context */
821 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
822 if (!session || !session->recv_skb) {
823 /* Not found? Pass to userspace to deal with */
824 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
825 "%s: no session found (%u/%u). Passing up.\n",
826 tunnel->name, tunnel_id, session_id);
827 goto error;
828 }
829
830 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
831
832 return 0;
833
834 discard_bad_csum:
835 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
836 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
837 tunnel->stats.rx_errors++;
838 kfree_skb(skb);
839
840 return 0;
841
842 error:
843 /* Put UDP header back */
844 __skb_push(skb, sizeof(struct udphdr));
845
846 return 1;
847 }
848
849 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
850 * Return codes:
851 * 0 : success.
852 * <0: error
853 * >0: skb should be passed up to userspace as UDP.
854 */
l2tp_udp_encap_recv(struct sock * sk,struct sk_buff * skb)855 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
856 {
857 struct l2tp_tunnel *tunnel;
858
859 tunnel = l2tp_sock_to_tunnel(sk);
860 if (tunnel == NULL)
861 goto pass_up;
862
863 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
864 "%s: received %d bytes\n", tunnel->name, skb->len);
865
866 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
867 goto pass_up_put;
868
869 sock_put(sk);
870 return 0;
871
872 pass_up_put:
873 sock_put(sk);
874 pass_up:
875 return 1;
876 }
877 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
878
879 /************************************************************************
880 * Transmit handling
881 ***********************************************************************/
882
883 /* Build an L2TP header for the session into the buffer provided.
884 */
l2tp_build_l2tpv2_header(struct l2tp_session * session,void * buf)885 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
886 {
887 struct l2tp_tunnel *tunnel = session->tunnel;
888 __be16 *bufp = buf;
889 __be16 *optr = buf;
890 u16 flags = L2TP_HDR_VER_2;
891 u32 tunnel_id = tunnel->peer_tunnel_id;
892 u32 session_id = session->peer_session_id;
893
894 if (session->send_seq)
895 flags |= L2TP_HDRFLAG_S;
896
897 /* Setup L2TP header. */
898 *bufp++ = htons(flags);
899 *bufp++ = htons(tunnel_id);
900 *bufp++ = htons(session_id);
901 if (session->send_seq) {
902 *bufp++ = htons(session->ns);
903 *bufp++ = 0;
904 session->ns++;
905 session->ns &= 0xffff;
906 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
907 "%s: updated ns to %u\n", session->name, session->ns);
908 }
909
910 return bufp - optr;
911 }
912
l2tp_build_l2tpv3_header(struct l2tp_session * session,void * buf)913 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
914 {
915 struct l2tp_tunnel *tunnel = session->tunnel;
916 char *bufp = buf;
917 char *optr = bufp;
918
919 /* Setup L2TP header. The header differs slightly for UDP and
920 * IP encapsulations. For UDP, there is 4 bytes of flags.
921 */
922 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
923 u16 flags = L2TP_HDR_VER_3;
924 *((__be16 *) bufp) = htons(flags);
925 bufp += 2;
926 *((__be16 *) bufp) = 0;
927 bufp += 2;
928 }
929
930 *((__be32 *) bufp) = htonl(session->peer_session_id);
931 bufp += 4;
932 if (session->cookie_len) {
933 memcpy(bufp, &session->cookie[0], session->cookie_len);
934 bufp += session->cookie_len;
935 }
936 if (session->l2specific_len) {
937 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
938 u32 l2h = 0;
939 if (session->send_seq) {
940 l2h = 0x40000000 | session->ns;
941 session->ns++;
942 session->ns &= 0xffffff;
943 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
944 "%s: updated ns to %u\n", session->name, session->ns);
945 }
946
947 *((__be32 *) bufp) = htonl(l2h);
948 }
949 bufp += session->l2specific_len;
950 }
951 if (session->offset)
952 bufp += session->offset;
953
954 return bufp - optr;
955 }
956
l2tp_xmit_core(struct l2tp_session * session,struct sk_buff * skb,struct flowi * fl,size_t data_len)957 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
958 struct flowi *fl, size_t data_len)
959 {
960 struct l2tp_tunnel *tunnel = session->tunnel;
961 unsigned int len = skb->len;
962 int error;
963
964 /* Debug */
965 if (session->send_seq)
966 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
967 "%s: send %Zd bytes, ns=%u\n", session->name,
968 data_len, session->ns - 1);
969 else
970 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
971 "%s: send %Zd bytes\n", session->name, data_len);
972
973 if (session->debug & L2TP_MSG_DATA) {
974 int i;
975 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
976 unsigned char *datap = skb->data + uhlen;
977
978 printk(KERN_DEBUG "%s: xmit:", session->name);
979 for (i = 0; i < (len - uhlen); i++) {
980 printk(" %02X", *datap++);
981 if (i == 31) {
982 printk(" ...");
983 break;
984 }
985 }
986 printk("\n");
987 }
988
989 /* Queue the packet to IP for output */
990 skb->local_df = 1;
991 error = ip_queue_xmit(skb, fl);
992
993 /* Update stats */
994 if (error >= 0) {
995 tunnel->stats.tx_packets++;
996 tunnel->stats.tx_bytes += len;
997 session->stats.tx_packets++;
998 session->stats.tx_bytes += len;
999 } else {
1000 tunnel->stats.tx_errors++;
1001 session->stats.tx_errors++;
1002 }
1003
1004 return 0;
1005 }
1006
1007 /* Automatically called when the skb is freed.
1008 */
l2tp_sock_wfree(struct sk_buff * skb)1009 static void l2tp_sock_wfree(struct sk_buff *skb)
1010 {
1011 sock_put(skb->sk);
1012 }
1013
1014 /* For data skbs that we transmit, we associate with the tunnel socket
1015 * but don't do accounting.
1016 */
l2tp_skb_set_owner_w(struct sk_buff * skb,struct sock * sk)1017 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1018 {
1019 sock_hold(sk);
1020 skb->sk = sk;
1021 skb->destructor = l2tp_sock_wfree;
1022 }
1023
1024 /* If caller requires the skb to have a ppp header, the header must be
1025 * inserted in the skb data before calling this function.
1026 */
l2tp_xmit_skb(struct l2tp_session * session,struct sk_buff * skb,int hdr_len)1027 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1028 {
1029 int data_len = skb->len;
1030 struct l2tp_tunnel *tunnel = session->tunnel;
1031 struct sock *sk = tunnel->sock;
1032 struct flowi *fl;
1033 struct udphdr *uh;
1034 struct inet_sock *inet;
1035 __wsum csum;
1036 int old_headroom;
1037 int new_headroom;
1038 int headroom;
1039 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1040 int udp_len;
1041
1042 /* Check that there's enough headroom in the skb to insert IP,
1043 * UDP and L2TP headers. If not enough, expand it to
1044 * make room. Adjust truesize.
1045 */
1046 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1047 uhlen + hdr_len;
1048 old_headroom = skb_headroom(skb);
1049 if (skb_cow_head(skb, headroom)) {
1050 dev_kfree_skb(skb);
1051 goto abort;
1052 }
1053
1054 new_headroom = skb_headroom(skb);
1055 skb_orphan(skb);
1056 skb->truesize += new_headroom - old_headroom;
1057
1058 /* Setup L2TP header */
1059 session->build_header(session, __skb_push(skb, hdr_len));
1060
1061 /* Reset skb netfilter state */
1062 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1063 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1064 IPSKB_REROUTED);
1065 nf_reset(skb);
1066
1067 bh_lock_sock(sk);
1068 if (sock_owned_by_user(sk)) {
1069 dev_kfree_skb(skb);
1070 goto out_unlock;
1071 }
1072
1073 /* Get routing info from the tunnel socket */
1074 skb_dst_drop(skb);
1075 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1076
1077 inet = inet_sk(sk);
1078 fl = &inet->cork.fl;
1079 switch (tunnel->encap) {
1080 case L2TP_ENCAPTYPE_UDP:
1081 /* Setup UDP header */
1082 __skb_push(skb, sizeof(*uh));
1083 skb_reset_transport_header(skb);
1084 uh = udp_hdr(skb);
1085 uh->source = inet->inet_sport;
1086 uh->dest = inet->inet_dport;
1087 udp_len = uhlen + hdr_len + data_len;
1088 uh->len = htons(udp_len);
1089 uh->check = 0;
1090
1091 /* Calculate UDP checksum if configured to do so */
1092 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1093 skb->ip_summed = CHECKSUM_NONE;
1094 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1095 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1096 skb->ip_summed = CHECKSUM_COMPLETE;
1097 csum = skb_checksum(skb, 0, udp_len, 0);
1098 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1099 inet->inet_daddr,
1100 udp_len, IPPROTO_UDP, csum);
1101 if (uh->check == 0)
1102 uh->check = CSUM_MANGLED_0;
1103 } else {
1104 skb->ip_summed = CHECKSUM_PARTIAL;
1105 skb->csum_start = skb_transport_header(skb) - skb->head;
1106 skb->csum_offset = offsetof(struct udphdr, check);
1107 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1108 inet->inet_daddr,
1109 udp_len, IPPROTO_UDP, 0);
1110 }
1111 break;
1112
1113 case L2TP_ENCAPTYPE_IP:
1114 break;
1115 }
1116
1117 l2tp_skb_set_owner_w(skb, sk);
1118
1119 l2tp_xmit_core(session, skb, fl, data_len);
1120 out_unlock:
1121 bh_unlock_sock(sk);
1122
1123 abort:
1124 return 0;
1125 }
1126 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1127
1128 /*****************************************************************************
1129 * Tinnel and session create/destroy.
1130 *****************************************************************************/
1131
1132 /* Tunnel socket destruct hook.
1133 * The tunnel context is deleted only when all session sockets have been
1134 * closed.
1135 */
l2tp_tunnel_destruct(struct sock * sk)1136 static void l2tp_tunnel_destruct(struct sock *sk)
1137 {
1138 struct l2tp_tunnel *tunnel;
1139
1140 tunnel = sk->sk_user_data;
1141 if (tunnel == NULL)
1142 goto end;
1143
1144 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1145 "%s: closing...\n", tunnel->name);
1146
1147 /* Close all sessions */
1148 l2tp_tunnel_closeall(tunnel);
1149
1150 switch (tunnel->encap) {
1151 case L2TP_ENCAPTYPE_UDP:
1152 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1153 (udp_sk(sk))->encap_type = 0;
1154 (udp_sk(sk))->encap_rcv = NULL;
1155 break;
1156 case L2TP_ENCAPTYPE_IP:
1157 break;
1158 }
1159
1160 /* Remove hooks into tunnel socket */
1161 tunnel->sock = NULL;
1162 sk->sk_destruct = tunnel->old_sk_destruct;
1163 sk->sk_user_data = NULL;
1164
1165 /* Call the original destructor */
1166 if (sk->sk_destruct)
1167 (*sk->sk_destruct)(sk);
1168
1169 /* We're finished with the socket */
1170 l2tp_tunnel_dec_refcount(tunnel);
1171
1172 end:
1173 return;
1174 }
1175
1176 /* When the tunnel is closed, all the attached sessions need to go too.
1177 */
l2tp_tunnel_closeall(struct l2tp_tunnel * tunnel)1178 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1179 {
1180 int hash;
1181 struct hlist_node *walk;
1182 struct hlist_node *tmp;
1183 struct l2tp_session *session;
1184
1185 BUG_ON(tunnel == NULL);
1186
1187 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1188 "%s: closing all sessions...\n", tunnel->name);
1189
1190 write_lock_bh(&tunnel->hlist_lock);
1191 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1192 again:
1193 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1194 session = hlist_entry(walk, struct l2tp_session, hlist);
1195
1196 PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
1197 "%s: closing session\n", session->name);
1198
1199 hlist_del_init(&session->hlist);
1200
1201 /* Since we should hold the sock lock while
1202 * doing any unbinding, we need to release the
1203 * lock we're holding before taking that lock.
1204 * Hold a reference to the sock so it doesn't
1205 * disappear as we're jumping between locks.
1206 */
1207 if (session->ref != NULL)
1208 (*session->ref)(session);
1209
1210 write_unlock_bh(&tunnel->hlist_lock);
1211
1212 if (tunnel->version != L2TP_HDR_VER_2) {
1213 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1214
1215 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1216 hlist_del_init_rcu(&session->global_hlist);
1217 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1218 synchronize_rcu();
1219 }
1220
1221 if (session->session_close != NULL)
1222 (*session->session_close)(session);
1223
1224 if (session->deref != NULL)
1225 (*session->deref)(session);
1226
1227 write_lock_bh(&tunnel->hlist_lock);
1228
1229 /* Now restart from the beginning of this hash
1230 * chain. We always remove a session from the
1231 * list so we are guaranteed to make forward
1232 * progress.
1233 */
1234 goto again;
1235 }
1236 }
1237 write_unlock_bh(&tunnel->hlist_lock);
1238 }
1239
1240 /* Really kill the tunnel.
1241 * Come here only when all sessions have been cleared from the tunnel.
1242 */
l2tp_tunnel_free(struct l2tp_tunnel * tunnel)1243 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1244 {
1245 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1246
1247 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1248 BUG_ON(tunnel->sock != NULL);
1249
1250 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1251 "%s: free...\n", tunnel->name);
1252
1253 /* Remove from tunnel list */
1254 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1255 list_del_rcu(&tunnel->list);
1256 kfree_rcu(tunnel, rcu);
1257 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1258
1259 atomic_dec(&l2tp_tunnel_count);
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 */
l2tp_tunnel_sock_create(u32 tunnel_id,u32 peer_tunnel_id,struct l2tp_tunnel_cfg * cfg,struct socket ** sockp)1266 static 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
1329 out:
1330 if ((err < 0) && sock) {
1331 sock_release(sock);
1332 *sockp = NULL;
1333 }
1334
1335 return err;
1336 }
1337
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)1338 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
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;
1451 err:
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 }
1463 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1464
1465 /* This function is used by the netlink TUNNEL_DELETE command.
1466 */
l2tp_tunnel_delete(struct l2tp_tunnel * tunnel)1467 int 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 }
1489 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1490
1491 /* Really kill the session.
1492 */
l2tp_session_free(struct l2tp_session * session)1493 void 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 }
1534 EXPORT_SYMBOL_GPL(l2tp_session_free);
1535
1536 /* This function is used by the netlink SESSION_DELETE command and by
1537 pseudowire modules.
1538 */
l2tp_session_delete(struct l2tp_session * session)1539 int 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 }
1548 EXPORT_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 */
l2tp_session_set_header_len(struct l2tp_session * session,int version)1554 static 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
l2tp_session_create(int priv_size,struct l2tp_tunnel * tunnel,u32 session_id,u32 peer_session_id,struct l2tp_session_cfg * cfg)1568 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
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 }
1649 EXPORT_SYMBOL_GPL(l2tp_session_create);
1650
1651 /*****************************************************************************
1652 * Init and cleanup
1653 *****************************************************************************/
1654
l2tp_init_net(struct net * net)1655 static __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
1671 static struct pernet_operations l2tp_net_ops = {
1672 .init = l2tp_init_net,
1673 .id = &l2tp_net_id,
1674 .size = sizeof(struct l2tp_net),
1675 };
1676
l2tp_init(void)1677 static 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
1687 out:
1688 return rc;
1689 }
1690
l2tp_exit(void)1691 static void __exit l2tp_exit(void)
1692 {
1693 unregister_pernet_device(&l2tp_net_ops);
1694 }
1695
1696 module_init(l2tp_init);
1697 module_exit(l2tp_exit);
1698
1699 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1700 MODULE_DESCRIPTION("L2TP core");
1701 MODULE_LICENSE("GPL");
1702 MODULE_VERSION(L2TP_DRV_VERSION);
1703
1704