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nohz_full: Force RCU's grace-period kthreads onto timekeeping CPU
[linux-2.6.git] / net / l2tp / l2tp_core.c
blobfeae495a0a30accd9eb5a88baf1c23095bb38d66
1 /*
2 * L2TP core.
3 *
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5 *
6 * This file contains some code of the original L2TPv2 pppol2tp
7 * driver, which has the following copyright:
8 *
9 * Authors: Martijn van Oosterhout <kleptog@svana.org>
10 * James Chapman (jchapman@katalix.com)
11 * Contributors:
12 * Michal Ostrowski <mostrows@speakeasy.net>
13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
14 * David S. Miller (davem@redhat.com)
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License version 2 as
18 * published by the Free Software Foundation.
19 */
20
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23 #include <linux/module.h>
24 #include <linux/string.h>
25 #include <linux/list.h>
26 #include <linux/rculist.h>
27 #include <linux/uaccess.h>
28
29 #include <linux/kernel.h>
30 #include <linux/spinlock.h>
31 #include <linux/kthread.h>
32 #include <linux/sched.h>
33 #include <linux/slab.h>
34 #include <linux/errno.h>
35 #include <linux/jiffies.h>
36
37 #include <linux/netdevice.h>
38 #include <linux/net.h>
39 #include <linux/inetdevice.h>
40 #include <linux/skbuff.h>
41 #include <linux/init.h>
42 #include <linux/in.h>
43 #include <linux/ip.h>
44 #include <linux/udp.h>
45 #include <linux/l2tp.h>
46 #include <linux/hash.h>
47 #include <linux/sort.h>
48 #include <linux/file.h>
49 #include <linux/nsproxy.h>
50 #include <net/net_namespace.h>
51 #include <net/netns/generic.h>
52 #include <net/dst.h>
53 #include <net/ip.h>
54 #include <net/udp.h>
55 #include <net/inet_common.h>
56 #include <net/xfrm.h>
57 #include <net/protocol.h>
58 #include <net/inet6_connection_sock.h>
59 #include <net/inet_ecn.h>
60 #include <net/ip6_route.h>
61 #include <net/ip6_checksum.h>
62
63 #include <asm/byteorder.h>
64 #include <linux/atomic.h>
65
66 #include "l2tp_core.h"
67
68 #define L2TP_DRV_VERSION "V2.0"
69
70 /* L2TP header constants */
71 #define L2TP_HDRFLAG_T 0x8000
72 #define L2TP_HDRFLAG_L 0x4000
73 #define L2TP_HDRFLAG_S 0x0800
74 #define L2TP_HDRFLAG_O 0x0200
75 #define L2TP_HDRFLAG_P 0x0100
76
77 #define L2TP_HDR_VER_MASK 0x000F
78 #define L2TP_HDR_VER_2 0x0002
79 #define L2TP_HDR_VER_3 0x0003
80
81 /* L2TPv3 default L2-specific sublayer */
82 #define L2TP_SLFLAG_S 0x40000000
83 #define L2TP_SL_SEQ_MASK 0x00ffffff
84
85 #define L2TP_HDR_SIZE_SEQ 10
86 #define L2TP_HDR_SIZE_NOSEQ 6
87
88 /* Default trace flags */
89 #define L2TP_DEFAULT_DEBUG_FLAGS 0
90
91 /* Private data stored for received packets in the skb.
92 */
93 struct l2tp_skb_cb {
94 u32 ns;
95 u16 has_seq;
96 u16 length;
97 unsigned long expires;
98 };
99
100 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
101
102 static atomic_t l2tp_tunnel_count;
103 static atomic_t l2tp_session_count;
104 static struct workqueue_struct *l2tp_wq;
105
106 /* per-net private data for this module */
107 static unsigned int l2tp_net_id;
108 struct l2tp_net {
109 struct list_head l2tp_tunnel_list;
110 spinlock_t l2tp_tunnel_list_lock;
111 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
112 spinlock_t l2tp_session_hlist_lock;
113 };
114
115 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
116 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
117
118 static inline struct l2tp_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 */
128 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
129 {
130 atomic_inc(&tunnel->ref_count);
131 }
132
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 *
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 */
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 */
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 */
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 *
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 */
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
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 */
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 */
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
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 */
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 */
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 session->nr &= session->nr_max;
418
419 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
420 session->name, session->nr);
421 }
422
423 /* call private receive handler */
424 if (session->recv_skb != NULL)
425 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
426 else
427 kfree_skb(skb);
428
429 if (session->deref)
430 (*session->deref)(session);
431 }
432
433 /* Dequeue skbs from the session's reorder_q, subject to packet order.
434 * Skbs that have been in the queue for too long are simply discarded.
435 */
436 static void l2tp_recv_dequeue(struct l2tp_session *session)
437 {
438 struct sk_buff *skb;
439 struct sk_buff *tmp;
440
441 /* If the pkt at the head of the queue has the nr that we
442 * expect to send up next, dequeue it and any other
443 * in-sequence packets behind it.
444 */
445 start:
446 spin_lock_bh(&session->reorder_q.lock);
447 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
448 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
449 atomic_long_inc(&session->stats.rx_seq_discards);
450 atomic_long_inc(&session->stats.rx_errors);
451 l2tp_dbg(session, L2TP_MSG_SEQ,
452 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
453 session->name, L2TP_SKB_CB(skb)->ns,
454 L2TP_SKB_CB(skb)->length, session->nr,
455 skb_queue_len(&session->reorder_q));
456 session->reorder_skip = 1;
457 __skb_unlink(skb, &session->reorder_q);
458 kfree_skb(skb);
459 if (session->deref)
460 (*session->deref)(session);
461 continue;
462 }
463
464 if (L2TP_SKB_CB(skb)->has_seq) {
465 if (session->reorder_skip) {
466 l2tp_dbg(session, L2TP_MSG_SEQ,
467 "%s: advancing nr to next pkt: %u -> %u",
468 session->name, session->nr,
469 L2TP_SKB_CB(skb)->ns);
470 session->reorder_skip = 0;
471 session->nr = L2TP_SKB_CB(skb)->ns;
472 }
473 if (L2TP_SKB_CB(skb)->ns != session->nr) {
474 l2tp_dbg(session, L2TP_MSG_SEQ,
475 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
476 session->name, L2TP_SKB_CB(skb)->ns,
477 L2TP_SKB_CB(skb)->length, session->nr,
478 skb_queue_len(&session->reorder_q));
479 goto out;
480 }
481 }
482 __skb_unlink(skb, &session->reorder_q);
483
484 /* Process the skb. We release the queue lock while we
485 * do so to let other contexts process the queue.
486 */
487 spin_unlock_bh(&session->reorder_q.lock);
488 l2tp_recv_dequeue_skb(session, skb);
489 goto start;
490 }
491
492 out:
493 spin_unlock_bh(&session->reorder_q.lock);
494 }
495
496 static inline int l2tp_verify_udp_checksum(struct sock *sk,
497 struct sk_buff *skb)
498 {
499 struct udphdr *uh = udp_hdr(skb);
500 u16 ulen = ntohs(uh->len);
501 __wsum psum;
502
503 if (sk->sk_no_check || skb_csum_unnecessary(skb))
504 return 0;
505
506 #if IS_ENABLED(CONFIG_IPV6)
507 if (sk->sk_family == PF_INET6) {
508 if (!uh->check) {
509 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
510 return 1;
511 }
512 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
513 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
514 &ipv6_hdr(skb)->daddr, ulen,
515 IPPROTO_UDP, skb->csum)) {
516 skb->ip_summed = CHECKSUM_UNNECESSARY;
517 return 0;
518 }
519 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
520 &ipv6_hdr(skb)->daddr,
521 skb->len, IPPROTO_UDP,
522 0));
523 } else
524 #endif
525 {
526 struct inet_sock *inet;
527 if (!uh->check)
528 return 0;
529 inet = inet_sk(sk);
530 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
531 ulen, IPPROTO_UDP, 0);
532
533 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
534 !csum_fold(csum_add(psum, skb->csum)))
535 return 0;
536 skb->csum = psum;
537 }
538
539 return __skb_checksum_complete(skb);
540 }
541
542 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
543 {
544 u32 nws;
545
546 if (nr >= session->nr)
547 nws = nr - session->nr;
548 else
549 nws = (session->nr_max + 1) - (session->nr - nr);
550
551 return nws < session->nr_window_size;
552 }
553
554 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
555 * acceptable, else non-zero.
556 */
557 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
558 {
559 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
560 /* Packet sequence number is outside allowed window.
561 * Discard it.
562 */
563 l2tp_dbg(session, L2TP_MSG_SEQ,
564 "%s: pkt %u len %d discarded, outside window, nr=%u\n",
565 session->name, L2TP_SKB_CB(skb)->ns,
566 L2TP_SKB_CB(skb)->length, session->nr);
567 goto discard;
568 }
569
570 if (session->reorder_timeout != 0) {
571 /* Packet reordering enabled. Add skb to session's
572 * reorder queue, in order of ns.
573 */
574 l2tp_recv_queue_skb(session, skb);
575 goto out;
576 }
577
578 /* Packet reordering disabled. Discard out-of-sequence packets, while
579 * tracking the number if in-sequence packets after the first OOS packet
580 * is seen. After nr_oos_count_max in-sequence packets, reset the
581 * sequence number to re-enable packet reception.
582 */
583 if (L2TP_SKB_CB(skb)->ns == session->nr) {
584 skb_queue_tail(&session->reorder_q, skb);
585 } else {
586 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
587 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
588
589 if (nr_oos == nr_next)
590 session->nr_oos_count++;
591 else
592 session->nr_oos_count = 0;
593
594 session->nr_oos = nr_oos;
595 if (session->nr_oos_count > session->nr_oos_count_max) {
596 session->reorder_skip = 1;
597 l2tp_dbg(session, L2TP_MSG_SEQ,
598 "%s: %d oos packets received. Resetting sequence numbers\n",
599 session->name, session->nr_oos_count);
600 }
601 if (!session->reorder_skip) {
602 atomic_long_inc(&session->stats.rx_seq_discards);
603 l2tp_dbg(session, L2TP_MSG_SEQ,
604 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
605 session->name, L2TP_SKB_CB(skb)->ns,
606 L2TP_SKB_CB(skb)->length, session->nr,
607 skb_queue_len(&session->reorder_q));
608 goto discard;
609 }
610 skb_queue_tail(&session->reorder_q, skb);
611 }
612
613 out:
614 return 0;
615
616 discard:
617 return 1;
618 }
619
620 /* Do receive processing of L2TP data frames. We handle both L2TPv2
621 * and L2TPv3 data frames here.
622 *
623 * L2TPv2 Data Message Header
624 *
625 * 0 1 2 3
626 * 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
627 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
628 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
629 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
630 * | Tunnel ID | Session ID |
631 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
632 * | Ns (opt) | Nr (opt) |
633 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
634 * | Offset Size (opt) | Offset pad... (opt)
635 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
636 *
637 * Data frames are marked by T=0. All other fields are the same as
638 * those in L2TP control frames.
639 *
640 * L2TPv3 Data Message Header
641 *
642 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
643 * | L2TP Session Header |
644 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
645 * | L2-Specific Sublayer |
646 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
647 * | Tunnel Payload ...
648 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
649 *
650 * L2TPv3 Session Header Over IP
651 *
652 * 0 1 2 3
653 * 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
654 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
655 * | Session ID |
656 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
657 * | Cookie (optional, maximum 64 bits)...
658 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
659 * |
660 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
661 *
662 * L2TPv3 L2-Specific Sublayer Format
663 *
664 * 0 1 2 3
665 * 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
666 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
667 * |x|S|x|x|x|x|x|x| Sequence Number |
668 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
669 *
670 * Cookie value, sublayer format and offset (pad) are negotiated with
671 * the peer when the session is set up. Unlike L2TPv2, we do not need
672 * to parse the packet header to determine if optional fields are
673 * present.
674 *
675 * Caller must already have parsed the frame and determined that it is
676 * a data (not control) frame before coming here. Fields up to the
677 * session-id have already been parsed and ptr points to the data
678 * after the session-id.
679 */
680 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
681 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
682 int length, int (*payload_hook)(struct sk_buff *skb))
683 {
684 struct l2tp_tunnel *tunnel = session->tunnel;
685 int offset;
686 u32 ns, nr;
687
688 /* The ref count is increased since we now hold a pointer to
689 * the session. Take care to decrement the refcnt when exiting
690 * this function from now on...
691 */
692 l2tp_session_inc_refcount(session);
693 if (session->ref)
694 (*session->ref)(session);
695
696 /* Parse and check optional cookie */
697 if (session->peer_cookie_len > 0) {
698 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
699 l2tp_info(tunnel, L2TP_MSG_DATA,
700 "%s: cookie mismatch (%u/%u). Discarding.\n",
701 tunnel->name, tunnel->tunnel_id,
702 session->session_id);
703 atomic_long_inc(&session->stats.rx_cookie_discards);
704 goto discard;
705 }
706 ptr += session->peer_cookie_len;
707 }
708
709 /* Handle the optional sequence numbers. Sequence numbers are
710 * in different places for L2TPv2 and L2TPv3.
711 *
712 * If we are the LAC, enable/disable sequence numbers under
713 * the control of the LNS. If no sequence numbers present but
714 * we were expecting them, discard frame.
715 */
716 ns = nr = 0;
717 L2TP_SKB_CB(skb)->has_seq = 0;
718 if (tunnel->version == L2TP_HDR_VER_2) {
719 if (hdrflags & L2TP_HDRFLAG_S) {
720 ns = ntohs(*(__be16 *) ptr);
721 ptr += 2;
722 nr = ntohs(*(__be16 *) ptr);
723 ptr += 2;
724
725 /* Store L2TP info in the skb */
726 L2TP_SKB_CB(skb)->ns = ns;
727 L2TP_SKB_CB(skb)->has_seq = 1;
728
729 l2tp_dbg(session, L2TP_MSG_SEQ,
730 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
731 session->name, ns, nr, session->nr);
732 }
733 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
734 u32 l2h = ntohl(*(__be32 *) ptr);
735
736 if (l2h & 0x40000000) {
737 ns = l2h & 0x00ffffff;
738
739 /* Store L2TP info in the skb */
740 L2TP_SKB_CB(skb)->ns = ns;
741 L2TP_SKB_CB(skb)->has_seq = 1;
742
743 l2tp_dbg(session, L2TP_MSG_SEQ,
744 "%s: recv data ns=%u, session nr=%u\n",
745 session->name, ns, session->nr);
746 }
747 }
748
749 /* Advance past L2-specific header, if present */
750 ptr += session->l2specific_len;
751
752 if (L2TP_SKB_CB(skb)->has_seq) {
753 /* Received a packet with sequence numbers. If we're the LNS,
754 * check if we sre sending sequence numbers and if not,
755 * configure it so.
756 */
757 if ((!session->lns_mode) && (!session->send_seq)) {
758 l2tp_info(session, L2TP_MSG_SEQ,
759 "%s: requested to enable seq numbers by LNS\n",
760 session->name);
761 session->send_seq = -1;
762 l2tp_session_set_header_len(session, tunnel->version);
763 }
764 } else {
765 /* No sequence numbers.
766 * If user has configured mandatory sequence numbers, discard.
767 */
768 if (session->recv_seq) {
769 l2tp_warn(session, L2TP_MSG_SEQ,
770 "%s: recv data has no seq numbers when required. Discarding.\n",
771 session->name);
772 atomic_long_inc(&session->stats.rx_seq_discards);
773 goto discard;
774 }
775
776 /* If we're the LAC and we're sending sequence numbers, the
777 * LNS has requested that we no longer send sequence numbers.
778 * If we're the LNS and we're sending sequence numbers, the
779 * LAC is broken. Discard the frame.
780 */
781 if ((!session->lns_mode) && (session->send_seq)) {
782 l2tp_info(session, L2TP_MSG_SEQ,
783 "%s: requested to disable seq numbers by LNS\n",
784 session->name);
785 session->send_seq = 0;
786 l2tp_session_set_header_len(session, tunnel->version);
787 } else if (session->send_seq) {
788 l2tp_warn(session, L2TP_MSG_SEQ,
789 "%s: recv data has no seq numbers when required. Discarding.\n",
790 session->name);
791 atomic_long_inc(&session->stats.rx_seq_discards);
792 goto discard;
793 }
794 }
795
796 /* Session data offset is handled differently for L2TPv2 and
797 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
798 * the header. For L2TPv3, the offset is negotiated using AVPs
799 * in the session setup control protocol.
800 */
801 if (tunnel->version == L2TP_HDR_VER_2) {
802 /* If offset bit set, skip it. */
803 if (hdrflags & L2TP_HDRFLAG_O) {
804 offset = ntohs(*(__be16 *)ptr);
805 ptr += 2 + offset;
806 }
807 } else
808 ptr += session->offset;
809
810 offset = ptr - optr;
811 if (!pskb_may_pull(skb, offset))
812 goto discard;
813
814 __skb_pull(skb, offset);
815
816 /* If caller wants to process the payload before we queue the
817 * packet, do so now.
818 */
819 if (payload_hook)
820 if ((*payload_hook)(skb))
821 goto discard;
822
823 /* Prepare skb for adding to the session's reorder_q. Hold
824 * packets for max reorder_timeout or 1 second if not
825 * reordering.
826 */
827 L2TP_SKB_CB(skb)->length = length;
828 L2TP_SKB_CB(skb)->expires = jiffies +
829 (session->reorder_timeout ? session->reorder_timeout : HZ);
830
831 /* Add packet to the session's receive queue. Reordering is done here, if
832 * enabled. Saved L2TP protocol info is stored in skb->sb[].
833 */
834 if (L2TP_SKB_CB(skb)->has_seq) {
835 if (l2tp_recv_data_seq(session, skb))
836 goto discard;
837 } else {
838 /* No sequence numbers. Add the skb to the tail of the
839 * reorder queue. This ensures that it will be
840 * delivered after all previous sequenced skbs.
841 */
842 skb_queue_tail(&session->reorder_q, skb);
843 }
844
845 /* Try to dequeue as many skbs from reorder_q as we can. */
846 l2tp_recv_dequeue(session);
847
848 l2tp_session_dec_refcount(session);
849
850 return;
851
852 discard:
853 atomic_long_inc(&session->stats.rx_errors);
854 kfree_skb(skb);
855
856 if (session->deref)
857 (*session->deref)(session);
858
859 l2tp_session_dec_refcount(session);
860 }
861 EXPORT_SYMBOL(l2tp_recv_common);
862
863 /* Drop skbs from the session's reorder_q
864 */
865 int l2tp_session_queue_purge(struct l2tp_session *session)
866 {
867 struct sk_buff *skb = NULL;
868 BUG_ON(!session);
869 BUG_ON(session->magic != L2TP_SESSION_MAGIC);
870 while ((skb = skb_dequeue(&session->reorder_q))) {
871 atomic_long_inc(&session->stats.rx_errors);
872 kfree_skb(skb);
873 if (session->deref)
874 (*session->deref)(session);
875 }
876 return 0;
877 }
878 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
879
880 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
881 * here. The skb is not on a list when we get here.
882 * Returns 0 if the packet was a data packet and was successfully passed on.
883 * Returns 1 if the packet was not a good data packet and could not be
884 * forwarded. All such packets are passed up to userspace to deal with.
885 */
886 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
887 int (*payload_hook)(struct sk_buff *skb))
888 {
889 struct l2tp_session *session = NULL;
890 unsigned char *ptr, *optr;
891 u16 hdrflags;
892 u32 tunnel_id, session_id;
893 u16 version;
894 int length;
895
896 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
897 goto discard_bad_csum;
898
899 /* UDP always verifies the packet length. */
900 __skb_pull(skb, sizeof(struct udphdr));
901
902 /* Short packet? */
903 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
904 l2tp_info(tunnel, L2TP_MSG_DATA,
905 "%s: recv short packet (len=%d)\n",
906 tunnel->name, skb->len);
907 goto error;
908 }
909
910 /* Trace packet contents, if enabled */
911 if (tunnel->debug & L2TP_MSG_DATA) {
912 length = min(32u, skb->len);
913 if (!pskb_may_pull(skb, length))
914 goto error;
915
916 pr_debug("%s: recv\n", tunnel->name);
917 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
918 }
919
920 /* Point to L2TP header */
921 optr = ptr = skb->data;
922
923 /* Get L2TP header flags */
924 hdrflags = ntohs(*(__be16 *) ptr);
925
926 /* Check protocol version */
927 version = hdrflags & L2TP_HDR_VER_MASK;
928 if (version != tunnel->version) {
929 l2tp_info(tunnel, L2TP_MSG_DATA,
930 "%s: recv protocol version mismatch: got %d expected %d\n",
931 tunnel->name, version, tunnel->version);
932 goto error;
933 }
934
935 /* Get length of L2TP packet */
936 length = skb->len;
937
938 /* If type is control packet, it is handled by userspace. */
939 if (hdrflags & L2TP_HDRFLAG_T) {
940 l2tp_dbg(tunnel, L2TP_MSG_DATA,
941 "%s: recv control packet, len=%d\n",
942 tunnel->name, length);
943 goto error;
944 }
945
946 /* Skip flags */
947 ptr += 2;
948
949 if (tunnel->version == L2TP_HDR_VER_2) {
950 /* If length is present, skip it */
951 if (hdrflags & L2TP_HDRFLAG_L)
952 ptr += 2;
953
954 /* Extract tunnel and session ID */
955 tunnel_id = ntohs(*(__be16 *) ptr);
956 ptr += 2;
957 session_id = ntohs(*(__be16 *) ptr);
958 ptr += 2;
959 } else {
960 ptr += 2; /* skip reserved bits */
961 tunnel_id = tunnel->tunnel_id;
962 session_id = ntohl(*(__be32 *) ptr);
963 ptr += 4;
964 }
965
966 /* Find the session context */
967 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
968 if (!session || !session->recv_skb) {
969 /* Not found? Pass to userspace to deal with */
970 l2tp_info(tunnel, L2TP_MSG_DATA,
971 "%s: no session found (%u/%u). Passing up.\n",
972 tunnel->name, tunnel_id, session_id);
973 goto error;
974 }
975
976 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
977
978 return 0;
979
980 discard_bad_csum:
981 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
982 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
983 atomic_long_inc(&tunnel->stats.rx_errors);
984 kfree_skb(skb);
985
986 return 0;
987
988 error:
989 /* Put UDP header back */
990 __skb_push(skb, sizeof(struct udphdr));
991
992 return 1;
993 }
994
995 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
996 * Return codes:
997 * 0 : success.
998 * <0: error
999 * >0: skb should be passed up to userspace as UDP.
1000 */
1001 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1002 {
1003 struct l2tp_tunnel *tunnel;
1004
1005 tunnel = l2tp_sock_to_tunnel(sk);
1006 if (tunnel == NULL)
1007 goto pass_up;
1008
1009 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1010 tunnel->name, skb->len);
1011
1012 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1013 goto pass_up_put;
1014
1015 sock_put(sk);
1016 return 0;
1017
1018 pass_up_put:
1019 sock_put(sk);
1020 pass_up:
1021 return 1;
1022 }
1023 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1024
1025 /************************************************************************
1026 * Transmit handling
1027 ***********************************************************************/
1028
1029 /* Build an L2TP header for the session into the buffer provided.
1030 */
1031 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1032 {
1033 struct l2tp_tunnel *tunnel = session->tunnel;
1034 __be16 *bufp = buf;
1035 __be16 *optr = buf;
1036 u16 flags = L2TP_HDR_VER_2;
1037 u32 tunnel_id = tunnel->peer_tunnel_id;
1038 u32 session_id = session->peer_session_id;
1039
1040 if (session->send_seq)
1041 flags |= L2TP_HDRFLAG_S;
1042
1043 /* Setup L2TP header. */
1044 *bufp++ = htons(flags);
1045 *bufp++ = htons(tunnel_id);
1046 *bufp++ = htons(session_id);
1047 if (session->send_seq) {
1048 *bufp++ = htons(session->ns);
1049 *bufp++ = 0;
1050 session->ns++;
1051 session->ns &= 0xffff;
1052 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1053 session->name, session->ns);
1054 }
1055
1056 return bufp - optr;
1057 }
1058
1059 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1060 {
1061 struct l2tp_tunnel *tunnel = session->tunnel;
1062 char *bufp = buf;
1063 char *optr = bufp;
1064
1065 /* Setup L2TP header. The header differs slightly for UDP and
1066 * IP encapsulations. For UDP, there is 4 bytes of flags.
1067 */
1068 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1069 u16 flags = L2TP_HDR_VER_3;
1070 *((__be16 *) bufp) = htons(flags);
1071 bufp += 2;
1072 *((__be16 *) bufp) = 0;
1073 bufp += 2;
1074 }
1075
1076 *((__be32 *) bufp) = htonl(session->peer_session_id);
1077 bufp += 4;
1078 if (session->cookie_len) {
1079 memcpy(bufp, &session->cookie[0], session->cookie_len);
1080 bufp += session->cookie_len;
1081 }
1082 if (session->l2specific_len) {
1083 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1084 u32 l2h = 0;
1085 if (session->send_seq) {
1086 l2h = 0x40000000 | session->ns;
1087 session->ns++;
1088 session->ns &= 0xffffff;
1089 l2tp_dbg(session, L2TP_MSG_SEQ,
1090 "%s: updated ns to %u\n",
1091 session->name, session->ns);
1092 }
1093
1094 *((__be32 *) bufp) = htonl(l2h);
1095 }
1096 bufp += session->l2specific_len;
1097 }
1098 if (session->offset)
1099 bufp += session->offset;
1100
1101 return bufp - optr;
1102 }
1103
1104 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1105 struct flowi *fl, size_t data_len)
1106 {
1107 struct l2tp_tunnel *tunnel = session->tunnel;
1108 unsigned int len = skb->len;
1109 int error;
1110
1111 /* Debug */
1112 if (session->send_seq)
1113 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1114 session->name, data_len, session->ns - 1);
1115 else
1116 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1117 session->name, data_len);
1118
1119 if (session->debug & L2TP_MSG_DATA) {
1120 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1121 unsigned char *datap = skb->data + uhlen;
1122
1123 pr_debug("%s: xmit\n", session->name);
1124 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1125 datap, min_t(size_t, 32, len - uhlen));
1126 }
1127
1128 /* Queue the packet to IP for output */
1129 skb->local_df = 1;
1130 #if IS_ENABLED(CONFIG_IPV6)
1131 if (skb->sk->sk_family == PF_INET6)
1132 error = inet6_csk_xmit(skb, NULL);
1133 else
1134 #endif
1135 error = ip_queue_xmit(skb, fl);
1136
1137 /* Update stats */
1138 if (error >= 0) {
1139 atomic_long_inc(&tunnel->stats.tx_packets);
1140 atomic_long_add(len, &tunnel->stats.tx_bytes);
1141 atomic_long_inc(&session->stats.tx_packets);
1142 atomic_long_add(len, &session->stats.tx_bytes);
1143 } else {
1144 atomic_long_inc(&tunnel->stats.tx_errors);
1145 atomic_long_inc(&session->stats.tx_errors);
1146 }
1147
1148 return 0;
1149 }
1150
1151 /* Automatically called when the skb is freed.
1152 */
1153 static void l2tp_sock_wfree(struct sk_buff *skb)
1154 {
1155 sock_put(skb->sk);
1156 }
1157
1158 /* For data skbs that we transmit, we associate with the tunnel socket
1159 * but don't do accounting.
1160 */
1161 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1162 {
1163 sock_hold(sk);
1164 skb->sk = sk;
1165 skb->destructor = l2tp_sock_wfree;
1166 }
1167
1168 #if IS_ENABLED(CONFIG_IPV6)
1169 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1170 int udp_len)
1171 {
1172 struct ipv6_pinfo *np = inet6_sk(sk);
1173 struct udphdr *uh = udp_hdr(skb);
1174
1175 if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1176 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1177 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1178 skb->ip_summed = CHECKSUM_UNNECESSARY;
1179 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1180 IPPROTO_UDP, csum);
1181 if (uh->check == 0)
1182 uh->check = CSUM_MANGLED_0;
1183 } else {
1184 skb->ip_summed = CHECKSUM_PARTIAL;
1185 skb->csum_start = skb_transport_header(skb) - skb->head;
1186 skb->csum_offset = offsetof(struct udphdr, check);
1187 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1188 udp_len, IPPROTO_UDP, 0);
1189 }
1190 }
1191 #endif
1192
1193 /* If caller requires the skb to have a ppp header, the header must be
1194 * inserted in the skb data before calling this function.
1195 */
1196 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1197 {
1198 int data_len = skb->len;
1199 struct l2tp_tunnel *tunnel = session->tunnel;
1200 struct sock *sk = tunnel->sock;
1201 struct flowi *fl;
1202 struct udphdr *uh;
1203 struct inet_sock *inet;
1204 __wsum csum;
1205 int headroom;
1206 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1207 int udp_len;
1208 int ret = NET_XMIT_SUCCESS;
1209
1210 /* Check that there's enough headroom in the skb to insert IP,
1211 * UDP and L2TP headers. If not enough, expand it to
1212 * make room. Adjust truesize.
1213 */
1214 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1215 uhlen + hdr_len;
1216 if (skb_cow_head(skb, headroom)) {
1217 kfree_skb(skb);
1218 return NET_XMIT_DROP;
1219 }
1220
1221 skb_orphan(skb);
1222 /* Setup L2TP header */
1223 session->build_header(session, __skb_push(skb, hdr_len));
1224
1225 /* Reset skb netfilter state */
1226 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1227 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1228 IPSKB_REROUTED);
1229 nf_reset(skb);
1230
1231 bh_lock_sock(sk);
1232 if (sock_owned_by_user(sk)) {
1233 kfree_skb(skb);
1234 ret = NET_XMIT_DROP;
1235 goto out_unlock;
1236 }
1237
1238 /* Get routing info from the tunnel socket */
1239 skb_dst_drop(skb);
1240 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1241
1242 inet = inet_sk(sk);
1243 fl = &inet->cork.fl;
1244 switch (tunnel->encap) {
1245 case L2TP_ENCAPTYPE_UDP:
1246 /* Setup UDP header */
1247 __skb_push(skb, sizeof(*uh));
1248 skb_reset_transport_header(skb);
1249 uh = udp_hdr(skb);
1250 uh->source = inet->inet_sport;
1251 uh->dest = inet->inet_dport;
1252 udp_len = uhlen + hdr_len + data_len;
1253 uh->len = htons(udp_len);
1254 uh->check = 0;
1255
1256 /* Calculate UDP checksum if configured to do so */
1257 #if IS_ENABLED(CONFIG_IPV6)
1258 if (sk->sk_family == PF_INET6)
1259 l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1260 else
1261 #endif
1262 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1263 skb->ip_summed = CHECKSUM_NONE;
1264 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1265 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1266 skb->ip_summed = CHECKSUM_COMPLETE;
1267 csum = skb_checksum(skb, 0, udp_len, 0);
1268 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1269 inet->inet_daddr,
1270 udp_len, IPPROTO_UDP, csum);
1271 if (uh->check == 0)
1272 uh->check = CSUM_MANGLED_0;
1273 } else {
1274 skb->ip_summed = CHECKSUM_PARTIAL;
1275 skb->csum_start = skb_transport_header(skb) - skb->head;
1276 skb->csum_offset = offsetof(struct udphdr, check);
1277 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1278 inet->inet_daddr,
1279 udp_len, IPPROTO_UDP, 0);
1280 }
1281 break;
1282
1283 case L2TP_ENCAPTYPE_IP:
1284 break;
1285 }
1286
1287 l2tp_skb_set_owner_w(skb, sk);
1288
1289 l2tp_xmit_core(session, skb, fl, data_len);
1290 out_unlock:
1291 bh_unlock_sock(sk);
1292
1293 return ret;
1294 }
1295 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1296
1297 /*****************************************************************************
1298 * Tinnel and session create/destroy.
1299 *****************************************************************************/
1300
1301 /* Tunnel socket destruct hook.
1302 * The tunnel context is deleted only when all session sockets have been
1303 * closed.
1304 */
1305 static void l2tp_tunnel_destruct(struct sock *sk)
1306 {
1307 struct l2tp_tunnel *tunnel;
1308 struct l2tp_net *pn;
1309
1310 tunnel = sk->sk_user_data;
1311 if (tunnel == NULL)
1312 goto end;
1313
1314 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1315
1316
1317 /* Disable udp encapsulation */
1318 switch (tunnel->encap) {
1319 case L2TP_ENCAPTYPE_UDP:
1320 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1321 (udp_sk(sk))->encap_type = 0;
1322 (udp_sk(sk))->encap_rcv = NULL;
1323 (udp_sk(sk))->encap_destroy = NULL;
1324 break;
1325 case L2TP_ENCAPTYPE_IP:
1326 break;
1327 }
1328
1329 /* Remove hooks into tunnel socket */
1330 sk->sk_destruct = tunnel->old_sk_destruct;
1331 sk->sk_user_data = NULL;
1332 tunnel->sock = NULL;
1333
1334 /* Remove the tunnel struct from the tunnel list */
1335 pn = l2tp_pernet(tunnel->l2tp_net);
1336 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1337 list_del_rcu(&tunnel->list);
1338 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1339 atomic_dec(&l2tp_tunnel_count);
1340
1341 l2tp_tunnel_closeall(tunnel);
1342 l2tp_tunnel_dec_refcount(tunnel);
1343
1344 /* Call the original destructor */
1345 if (sk->sk_destruct)
1346 (*sk->sk_destruct)(sk);
1347 end:
1348 return;
1349 }
1350
1351 /* When the tunnel is closed, all the attached sessions need to go too.
1352 */
1353 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1354 {
1355 int hash;
1356 struct hlist_node *walk;
1357 struct hlist_node *tmp;
1358 struct l2tp_session *session;
1359
1360 BUG_ON(tunnel == NULL);
1361
1362 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1363 tunnel->name);
1364
1365 write_lock_bh(&tunnel->hlist_lock);
1366 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1367 again:
1368 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1369 session = hlist_entry(walk, struct l2tp_session, hlist);
1370
1371 l2tp_info(session, L2TP_MSG_CONTROL,
1372 "%s: closing session\n", session->name);
1373
1374 hlist_del_init(&session->hlist);
1375
1376 if (session->ref != NULL)
1377 (*session->ref)(session);
1378
1379 write_unlock_bh(&tunnel->hlist_lock);
1380
1381 __l2tp_session_unhash(session);
1382 l2tp_session_queue_purge(session);
1383
1384 if (session->session_close != NULL)
1385 (*session->session_close)(session);
1386
1387 if (session->deref != NULL)
1388 (*session->deref)(session);
1389
1390 l2tp_session_dec_refcount(session);
1391
1392 write_lock_bh(&tunnel->hlist_lock);
1393
1394 /* Now restart from the beginning of this hash
1395 * chain. We always remove a session from the
1396 * list so we are guaranteed to make forward
1397 * progress.
1398 */
1399 goto again;
1400 }
1401 }
1402 write_unlock_bh(&tunnel->hlist_lock);
1403 }
1404 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1405
1406 /* Tunnel socket destroy hook for UDP encapsulation */
1407 static void l2tp_udp_encap_destroy(struct sock *sk)
1408 {
1409 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1410 if (tunnel) {
1411 l2tp_tunnel_closeall(tunnel);
1412 sock_put(sk);
1413 }
1414 }
1415
1416 /* Really kill the tunnel.
1417 * Come here only when all sessions have been cleared from the tunnel.
1418 */
1419 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1420 {
1421 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1422 BUG_ON(tunnel->sock != NULL);
1423 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1424 kfree_rcu(tunnel, rcu);
1425 }
1426
1427 /* Workqueue tunnel deletion function */
1428 static void l2tp_tunnel_del_work(struct work_struct *work)
1429 {
1430 struct l2tp_tunnel *tunnel = NULL;
1431 struct socket *sock = NULL;
1432 struct sock *sk = NULL;
1433
1434 tunnel = container_of(work, struct l2tp_tunnel, del_work);
1435 sk = l2tp_tunnel_sock_lookup(tunnel);
1436 if (!sk)
1437 return;
1438
1439 sock = sk->sk_socket;
1440
1441 /* If the tunnel socket was created by userspace, then go through the
1442 * inet layer to shut the socket down, and let userspace close it.
1443 * Otherwise, if we created the socket directly within the kernel, use
1444 * the sk API to release it here.
1445 * In either case the tunnel resources are freed in the socket
1446 * destructor when the tunnel socket goes away.
1447 */
1448 if (tunnel->fd >= 0) {
1449 if (sock)
1450 inet_shutdown(sock, 2);
1451 } else {
1452 if (sock)
1453 kernel_sock_shutdown(sock, SHUT_RDWR);
1454 sk_release_kernel(sk);
1455 }
1456
1457 l2tp_tunnel_sock_put(sk);
1458 }
1459
1460 /* Create a socket for the tunnel, if one isn't set up by
1461 * userspace. This is used for static tunnels where there is no
1462 * managing L2TP daemon.
1463 *
1464 * Since we don't want these sockets to keep a namespace alive by
1465 * themselves, we drop the socket's namespace refcount after creation.
1466 * These sockets are freed when the namespace exits using the pernet
1467 * exit hook.
1468 */
1469 static int l2tp_tunnel_sock_create(struct net *net,
1470 u32 tunnel_id,
1471 u32 peer_tunnel_id,
1472 struct l2tp_tunnel_cfg *cfg,
1473 struct socket **sockp)
1474 {
1475 int err = -EINVAL;
1476 struct socket *sock = NULL;
1477 struct sockaddr_in udp_addr = {0};
1478 struct sockaddr_l2tpip ip_addr = {0};
1479 #if IS_ENABLED(CONFIG_IPV6)
1480 struct sockaddr_in6 udp6_addr = {0};
1481 struct sockaddr_l2tpip6 ip6_addr = {0};
1482 #endif
1483
1484 switch (cfg->encap) {
1485 case L2TP_ENCAPTYPE_UDP:
1486 #if IS_ENABLED(CONFIG_IPV6)
1487 if (cfg->local_ip6 && cfg->peer_ip6) {
1488 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1489 if (err < 0)
1490 goto out;
1491
1492 sk_change_net(sock->sk, net);
1493
1494 udp6_addr.sin6_family = AF_INET6;
1495 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1496 sizeof(udp6_addr.sin6_addr));
1497 udp6_addr.sin6_port = htons(cfg->local_udp_port);
1498 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1499 sizeof(udp6_addr));
1500 if (err < 0)
1501 goto out;
1502
1503 udp6_addr.sin6_family = AF_INET6;
1504 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1505 sizeof(udp6_addr.sin6_addr));
1506 udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1507 err = kernel_connect(sock,
1508 (struct sockaddr *) &udp6_addr,
1509 sizeof(udp6_addr), 0);
1510 if (err < 0)
1511 goto out;
1512 } else
1513 #endif
1514 {
1515 err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1516 if (err < 0)
1517 goto out;
1518
1519 sk_change_net(sock->sk, net);
1520
1521 udp_addr.sin_family = AF_INET;
1522 udp_addr.sin_addr = cfg->local_ip;
1523 udp_addr.sin_port = htons(cfg->local_udp_port);
1524 err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1525 sizeof(udp_addr));
1526 if (err < 0)
1527 goto out;
1528
1529 udp_addr.sin_family = AF_INET;
1530 udp_addr.sin_addr = cfg->peer_ip;
1531 udp_addr.sin_port = htons(cfg->peer_udp_port);
1532 err = kernel_connect(sock,
1533 (struct sockaddr *) &udp_addr,
1534 sizeof(udp_addr), 0);
1535 if (err < 0)
1536 goto out;
1537 }
1538
1539 if (!cfg->use_udp_checksums)
1540 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1541
1542 break;
1543
1544 case L2TP_ENCAPTYPE_IP:
1545 #if IS_ENABLED(CONFIG_IPV6)
1546 if (cfg->local_ip6 && cfg->peer_ip6) {
1547 err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1548 IPPROTO_L2TP, &sock);
1549 if (err < 0)
1550 goto out;
1551
1552 sk_change_net(sock->sk, net);
1553
1554 ip6_addr.l2tp_family = AF_INET6;
1555 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1556 sizeof(ip6_addr.l2tp_addr));
1557 ip6_addr.l2tp_conn_id = tunnel_id;
1558 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1559 sizeof(ip6_addr));
1560 if (err < 0)
1561 goto out;
1562
1563 ip6_addr.l2tp_family = AF_INET6;
1564 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1565 sizeof(ip6_addr.l2tp_addr));
1566 ip6_addr.l2tp_conn_id = peer_tunnel_id;
1567 err = kernel_connect(sock,
1568 (struct sockaddr *) &ip6_addr,
1569 sizeof(ip6_addr), 0);
1570 if (err < 0)
1571 goto out;
1572 } else
1573 #endif
1574 {
1575 err = sock_create_kern(AF_INET, SOCK_DGRAM,
1576 IPPROTO_L2TP, &sock);
1577 if (err < 0)
1578 goto out;
1579
1580 sk_change_net(sock->sk, net);
1581
1582 ip_addr.l2tp_family = AF_INET;
1583 ip_addr.l2tp_addr = cfg->local_ip;
1584 ip_addr.l2tp_conn_id = tunnel_id;
1585 err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1586 sizeof(ip_addr));
1587 if (err < 0)
1588 goto out;
1589
1590 ip_addr.l2tp_family = AF_INET;
1591 ip_addr.l2tp_addr = cfg->peer_ip;
1592 ip_addr.l2tp_conn_id = peer_tunnel_id;
1593 err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1594 sizeof(ip_addr), 0);
1595 if (err < 0)
1596 goto out;
1597 }
1598 break;
1599
1600 default:
1601 goto out;
1602 }
1603
1604 out:
1605 *sockp = sock;
1606 if ((err < 0) && sock) {
1607 kernel_sock_shutdown(sock, SHUT_RDWR);
1608 sk_release_kernel(sock->sk);
1609 *sockp = NULL;
1610 }
1611
1612 return err;
1613 }
1614
1615 static struct lock_class_key l2tp_socket_class;
1616
1617 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)
1618 {
1619 struct l2tp_tunnel *tunnel = NULL;
1620 int err;
1621 struct socket *sock = NULL;
1622 struct sock *sk = NULL;
1623 struct l2tp_net *pn;
1624 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1625
1626 /* Get the tunnel socket from the fd, which was opened by
1627 * the userspace L2TP daemon. If not specified, create a
1628 * kernel socket.
1629 */
1630 if (fd < 0) {
1631 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1632 cfg, &sock);
1633 if (err < 0)
1634 goto err;
1635 } else {
1636 sock = sockfd_lookup(fd, &err);
1637 if (!sock) {
1638 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1639 tunnel_id, fd, err);
1640 err = -EBADF;
1641 goto err;
1642 }
1643
1644 /* Reject namespace mismatches */
1645 if (!net_eq(sock_net(sock->sk), net)) {
1646 pr_err("tunl %u: netns mismatch\n", tunnel_id);
1647 err = -EINVAL;
1648 goto err;
1649 }
1650 }
1651
1652 sk = sock->sk;
1653
1654 if (cfg != NULL)
1655 encap = cfg->encap;
1656
1657 /* Quick sanity checks */
1658 switch (encap) {
1659 case L2TP_ENCAPTYPE_UDP:
1660 err = -EPROTONOSUPPORT;
1661 if (sk->sk_protocol != IPPROTO_UDP) {
1662 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1663 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1664 goto err;
1665 }
1666 break;
1667 case L2TP_ENCAPTYPE_IP:
1668 err = -EPROTONOSUPPORT;
1669 if (sk->sk_protocol != IPPROTO_L2TP) {
1670 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1671 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1672 goto err;
1673 }
1674 break;
1675 }
1676
1677 /* Check if this socket has already been prepped */
1678 tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1679 if (tunnel != NULL) {
1680 /* This socket has already been prepped */
1681 err = -EBUSY;
1682 goto err;
1683 }
1684
1685 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1686 if (tunnel == NULL) {
1687 err = -ENOMEM;
1688 goto err;
1689 }
1690
1691 tunnel->version = version;
1692 tunnel->tunnel_id = tunnel_id;
1693 tunnel->peer_tunnel_id = peer_tunnel_id;
1694 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1695
1696 tunnel->magic = L2TP_TUNNEL_MAGIC;
1697 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1698 rwlock_init(&tunnel->hlist_lock);
1699
1700 /* The net we belong to */
1701 tunnel->l2tp_net = net;
1702 pn = l2tp_pernet(net);
1703
1704 if (cfg != NULL)
1705 tunnel->debug = cfg->debug;
1706
1707 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1708 tunnel->encap = encap;
1709 if (encap == L2TP_ENCAPTYPE_UDP) {
1710 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1711 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1712 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1713 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
1714 #if IS_ENABLED(CONFIG_IPV6)
1715 if (sk->sk_family == PF_INET6)
1716 udpv6_encap_enable();
1717 else
1718 #endif
1719 udp_encap_enable();
1720 }
1721
1722 sk->sk_user_data = tunnel;
1723
1724 /* Hook on the tunnel socket destructor so that we can cleanup
1725 * if the tunnel socket goes away.
1726 */
1727 tunnel->old_sk_destruct = sk->sk_destruct;
1728 sk->sk_destruct = &l2tp_tunnel_destruct;
1729 tunnel->sock = sk;
1730 tunnel->fd = fd;
1731 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1732
1733 sk->sk_allocation = GFP_ATOMIC;
1734
1735 /* Init delete workqueue struct */
1736 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1737
1738 /* Add tunnel to our list */
1739 INIT_LIST_HEAD(&tunnel->list);
1740 atomic_inc(&l2tp_tunnel_count);
1741
1742 /* Bump the reference count. The tunnel context is deleted
1743 * only when this drops to zero. Must be done before list insertion
1744 */
1745 l2tp_tunnel_inc_refcount(tunnel);
1746 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1747 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1748 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1749
1750 err = 0;
1751 err:
1752 if (tunnelp)
1753 *tunnelp = tunnel;
1754
1755 /* If tunnel's socket was created by the kernel, it doesn't
1756 * have a file.
1757 */
1758 if (sock && sock->file)
1759 sockfd_put(sock);
1760
1761 return err;
1762 }
1763 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1764
1765 /* This function is used by the netlink TUNNEL_DELETE command.
1766 */
1767 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1768 {
1769 l2tp_tunnel_closeall(tunnel);
1770 return (false == queue_work(l2tp_wq, &tunnel->del_work));
1771 }
1772 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1773
1774 /* Really kill the session.
1775 */
1776 void l2tp_session_free(struct l2tp_session *session)
1777 {
1778 struct l2tp_tunnel *tunnel = session->tunnel;
1779
1780 BUG_ON(atomic_read(&session->ref_count) != 0);
1781
1782 if (tunnel) {
1783 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1784 if (session->session_id != 0)
1785 atomic_dec(&l2tp_session_count);
1786 sock_put(tunnel->sock);
1787 session->tunnel = NULL;
1788 l2tp_tunnel_dec_refcount(tunnel);
1789 }
1790
1791 kfree(session);
1792
1793 return;
1794 }
1795 EXPORT_SYMBOL_GPL(l2tp_session_free);
1796
1797 /* Remove an l2tp session from l2tp_core's hash lists.
1798 * Provides a tidyup interface for pseudowire code which can't just route all
1799 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1800 * callback.
1801 */
1802 void __l2tp_session_unhash(struct l2tp_session *session)
1803 {
1804 struct l2tp_tunnel *tunnel = session->tunnel;
1805
1806 /* Remove the session from core hashes */
1807 if (tunnel) {
1808 /* Remove from the per-tunnel hash */
1809 write_lock_bh(&tunnel->hlist_lock);
1810 hlist_del_init(&session->hlist);
1811 write_unlock_bh(&tunnel->hlist_lock);
1812
1813 /* For L2TPv3 we have a per-net hash: remove from there, too */
1814 if (tunnel->version != L2TP_HDR_VER_2) {
1815 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1816 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1817 hlist_del_init_rcu(&session->global_hlist);
1818 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1819 synchronize_rcu();
1820 }
1821 }
1822 }
1823 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1824
1825 /* This function is used by the netlink SESSION_DELETE command and by
1826 pseudowire modules.
1827 */
1828 int l2tp_session_delete(struct l2tp_session *session)
1829 {
1830 if (session->ref)
1831 (*session->ref)(session);
1832 __l2tp_session_unhash(session);
1833 l2tp_session_queue_purge(session);
1834 if (session->session_close != NULL)
1835 (*session->session_close)(session);
1836 if (session->deref)
1837 (*session->deref)(session);
1838 l2tp_session_dec_refcount(session);
1839 return 0;
1840 }
1841 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1842
1843 /* We come here whenever a session's send_seq, cookie_len or
1844 * l2specific_len parameters are set.
1845 */
1846 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1847 {
1848 if (version == L2TP_HDR_VER_2) {
1849 session->hdr_len = 6;
1850 if (session->send_seq)
1851 session->hdr_len += 4;
1852 } else {
1853 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1854 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1855 session->hdr_len += 4;
1856 }
1857
1858 }
1859
1860 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)
1861 {
1862 struct l2tp_session *session;
1863
1864 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1865 if (session != NULL) {
1866 session->magic = L2TP_SESSION_MAGIC;
1867 session->tunnel = tunnel;
1868
1869 session->session_id = session_id;
1870 session->peer_session_id = peer_session_id;
1871 session->nr = 0;
1872 if (tunnel->version == L2TP_HDR_VER_2)
1873 session->nr_max = 0xffff;
1874 else
1875 session->nr_max = 0xffffff;
1876 session->nr_window_size = session->nr_max / 2;
1877 session->nr_oos_count_max = 4;
1878
1879 /* Use NR of first received packet */
1880 session->reorder_skip = 1;
1881
1882 sprintf(&session->name[0], "sess %u/%u",
1883 tunnel->tunnel_id, session->session_id);
1884
1885 skb_queue_head_init(&session->reorder_q);
1886
1887 INIT_HLIST_NODE(&session->hlist);
1888 INIT_HLIST_NODE(&session->global_hlist);
1889
1890 /* Inherit debug options from tunnel */
1891 session->debug = tunnel->debug;
1892
1893 if (cfg) {
1894 session->pwtype = cfg->pw_type;
1895 session->debug = cfg->debug;
1896 session->mtu = cfg->mtu;
1897 session->mru = cfg->mru;
1898 session->send_seq = cfg->send_seq;
1899 session->recv_seq = cfg->recv_seq;
1900 session->lns_mode = cfg->lns_mode;
1901 session->reorder_timeout = cfg->reorder_timeout;
1902 session->offset = cfg->offset;
1903 session->l2specific_type = cfg->l2specific_type;
1904 session->l2specific_len = cfg->l2specific_len;
1905 session->cookie_len = cfg->cookie_len;
1906 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1907 session->peer_cookie_len = cfg->peer_cookie_len;
1908 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1909 }
1910
1911 if (tunnel->version == L2TP_HDR_VER_2)
1912 session->build_header = l2tp_build_l2tpv2_header;
1913 else
1914 session->build_header = l2tp_build_l2tpv3_header;
1915
1916 l2tp_session_set_header_len(session, tunnel->version);
1917
1918 /* Bump the reference count. The session context is deleted
1919 * only when this drops to zero.
1920 */
1921 l2tp_session_inc_refcount(session);
1922 l2tp_tunnel_inc_refcount(tunnel);
1923
1924 /* Ensure tunnel socket isn't deleted */
1925 sock_hold(tunnel->sock);
1926
1927 /* Add session to the tunnel's hash list */
1928 write_lock_bh(&tunnel->hlist_lock);
1929 hlist_add_head(&session->hlist,
1930 l2tp_session_id_hash(tunnel, session_id));
1931 write_unlock_bh(&tunnel->hlist_lock);
1932
1933 /* And to the global session list if L2TPv3 */
1934 if (tunnel->version != L2TP_HDR_VER_2) {
1935 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1936
1937 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1938 hlist_add_head_rcu(&session->global_hlist,
1939 l2tp_session_id_hash_2(pn, session_id));
1940 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1941 }
1942
1943 /* Ignore management session in session count value */
1944 if (session->session_id != 0)
1945 atomic_inc(&l2tp_session_count);
1946 }
1947
1948 return session;
1949 }
1950 EXPORT_SYMBOL_GPL(l2tp_session_create);
1951
1952 /*****************************************************************************
1953 * Init and cleanup
1954 *****************************************************************************/
1955
1956 static __net_init int l2tp_init_net(struct net *net)
1957 {
1958 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1959 int hash;
1960
1961 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1962 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1963
1964 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1965 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1966
1967 spin_lock_init(&pn->l2tp_session_hlist_lock);
1968
1969 return 0;
1970 }
1971
1972 static __net_exit void l2tp_exit_net(struct net *net)
1973 {
1974 struct l2tp_net *pn = l2tp_pernet(net);
1975 struct l2tp_tunnel *tunnel = NULL;
1976
1977 rcu_read_lock_bh();
1978 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1979 (void)l2tp_tunnel_delete(tunnel);
1980 }
1981 rcu_read_unlock_bh();
1982 }
1983
1984 static struct pernet_operations l2tp_net_ops = {
1985 .init = l2tp_init_net,
1986 .exit = l2tp_exit_net,
1987 .id = &l2tp_net_id,
1988 .size = sizeof(struct l2tp_net),
1989 };
1990
1991 static int __init l2tp_init(void)
1992 {
1993 int rc = 0;
1994
1995 rc = register_pernet_device(&l2tp_net_ops);
1996 if (rc)
1997 goto out;
1998
1999 l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
2000 if (!l2tp_wq) {
2001 pr_err("alloc_workqueue failed\n");
2002 rc = -ENOMEM;
2003 goto out;
2004 }
2005
2006 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
2007
2008 out:
2009 return rc;
2010 }
2011
2012 static void __exit l2tp_exit(void)
2013 {
2014 unregister_pernet_device(&l2tp_net_ops);
2015 if (l2tp_wq) {
2016 destroy_workqueue(l2tp_wq);
2017 l2tp_wq = NULL;
2018 }
2019 }
2020
2021 module_init(l2tp_init);
2022 module_exit(l2tp_exit);
2023
2024 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
2025 MODULE_DESCRIPTION("L2TP core");
2026 MODULE_LICENSE("GPL");
2027 MODULE_VERSION(L2TP_DRV_VERSION);
2028
Linus' kernel tree