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