l2tp: fix a lockdep splat
[linux-3.10.git] / net / l2tp / l2tp_core.c
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
105 /* per-net private data for this module */
106 static unsigned int l2tp_net_id;
107 struct l2tp_net {
108         struct list_head l2tp_tunnel_list;
109         spinlock_t l2tp_tunnel_list_lock;
110         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
111         spinlock_t l2tp_session_hlist_lock;
112 };
113
114 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
115 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
116 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
117
118 static inline struct l2tp_net *l2tp_pernet(struct net *net)
119 {
120         BUG_ON(!net);
121
122         return net_generic(net, l2tp_net_id);
123 }
124
125
126 /* Tunnel reference counts. Incremented per session that is added to
127  * the tunnel.
128  */
129 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
130 {
131         atomic_inc(&tunnel->ref_count);
132 }
133
134 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
135 {
136         if (atomic_dec_and_test(&tunnel->ref_count))
137                 l2tp_tunnel_free(tunnel);
138 }
139 #ifdef L2TP_REFCNT_DEBUG
140 #define l2tp_tunnel_inc_refcount(_t)                                    \
141 do {                                                                    \
142         pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n",        \
143                  __func__, __LINE__, (_t)->name,                        \
144                  atomic_read(&_t->ref_count));                          \
145         l2tp_tunnel_inc_refcount_1(_t);                                 \
146 } while (0)
147 #define l2tp_tunnel_dec_refcount(_t)
148 do {                                                                    \
149         pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n",        \
150                  __func__, __LINE__, (_t)->name,                        \
151                  atomic_read(&_t->ref_count));                          \
152         l2tp_tunnel_dec_refcount_1(_t);                                 \
153 } while (0)
154 #else
155 #define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
156 #define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
157 #endif
158
159 /* Session hash global list for L2TPv3.
160  * The session_id SHOULD be random according to RFC3931, but several
161  * L2TP implementations use incrementing session_ids.  So we do a real
162  * hash on the session_id, rather than a simple bitmask.
163  */
164 static inline struct hlist_head *
165 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
166 {
167         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
168
169 }
170
171 /* Lookup a session by id in the global session list
172  */
173 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
174 {
175         struct l2tp_net *pn = l2tp_pernet(net);
176         struct hlist_head *session_list =
177                 l2tp_session_id_hash_2(pn, session_id);
178         struct l2tp_session *session;
179         struct hlist_node *walk;
180
181         rcu_read_lock_bh();
182         hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
183                 if (session->session_id == session_id) {
184                         rcu_read_unlock_bh();
185                         return session;
186                 }
187         }
188         rcu_read_unlock_bh();
189
190         return NULL;
191 }
192
193 /* Session hash list.
194  * The session_id SHOULD be random according to RFC2661, but several
195  * L2TP implementations (Cisco and Microsoft) use incrementing
196  * session_ids.  So we do a real hash on the session_id, rather than a
197  * simple bitmask.
198  */
199 static inline struct hlist_head *
200 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
201 {
202         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
203 }
204
205 /* Lookup a session by id
206  */
207 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
208 {
209         struct hlist_head *session_list;
210         struct l2tp_session *session;
211         struct hlist_node *walk;
212
213         /* In L2TPv3, session_ids are unique over all tunnels and we
214          * sometimes need to look them up before we know the
215          * tunnel.
216          */
217         if (tunnel == NULL)
218                 return l2tp_session_find_2(net, session_id);
219
220         session_list = l2tp_session_id_hash(tunnel, session_id);
221         read_lock_bh(&tunnel->hlist_lock);
222         hlist_for_each_entry(session, walk, session_list, hlist) {
223                 if (session->session_id == session_id) {
224                         read_unlock_bh(&tunnel->hlist_lock);
225                         return session;
226                 }
227         }
228         read_unlock_bh(&tunnel->hlist_lock);
229
230         return NULL;
231 }
232 EXPORT_SYMBOL_GPL(l2tp_session_find);
233
234 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
235 {
236         int hash;
237         struct hlist_node *walk;
238         struct l2tp_session *session;
239         int count = 0;
240
241         read_lock_bh(&tunnel->hlist_lock);
242         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
243                 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
244                         if (++count > nth) {
245                                 read_unlock_bh(&tunnel->hlist_lock);
246                                 return session;
247                         }
248                 }
249         }
250
251         read_unlock_bh(&tunnel->hlist_lock);
252
253         return NULL;
254 }
255 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
256
257 /* Lookup a session by interface name.
258  * This is very inefficient but is only used by management interfaces.
259  */
260 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
261 {
262         struct l2tp_net *pn = l2tp_pernet(net);
263         int hash;
264         struct hlist_node *walk;
265         struct l2tp_session *session;
266
267         rcu_read_lock_bh();
268         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
269                 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
270                         if (!strcmp(session->ifname, ifname)) {
271                                 rcu_read_unlock_bh();
272                                 return session;
273                         }
274                 }
275         }
276
277         rcu_read_unlock_bh();
278
279         return NULL;
280 }
281 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
282
283 /* Lookup a tunnel by id
284  */
285 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
286 {
287         struct l2tp_tunnel *tunnel;
288         struct l2tp_net *pn = l2tp_pernet(net);
289
290         rcu_read_lock_bh();
291         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
292                 if (tunnel->tunnel_id == tunnel_id) {
293                         rcu_read_unlock_bh();
294                         return tunnel;
295                 }
296         }
297         rcu_read_unlock_bh();
298
299         return NULL;
300 }
301 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
302
303 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
304 {
305         struct l2tp_net *pn = l2tp_pernet(net);
306         struct l2tp_tunnel *tunnel;
307         int count = 0;
308
309         rcu_read_lock_bh();
310         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
311                 if (++count > nth) {
312                         rcu_read_unlock_bh();
313                         return tunnel;
314                 }
315         }
316
317         rcu_read_unlock_bh();
318
319         return NULL;
320 }
321 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
322
323 /*****************************************************************************
324  * Receive data handling
325  *****************************************************************************/
326
327 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
328  * number.
329  */
330 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
331 {
332         struct sk_buff *skbp;
333         struct sk_buff *tmp;
334         u32 ns = L2TP_SKB_CB(skb)->ns;
335         struct l2tp_stats *sstats;
336
337         spin_lock_bh(&session->reorder_q.lock);
338         sstats = &session->stats;
339         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
340                 if (L2TP_SKB_CB(skbp)->ns > ns) {
341                         __skb_queue_before(&session->reorder_q, skbp, skb);
342                         l2tp_dbg(session, L2TP_MSG_SEQ,
343                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
344                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
345                                  skb_queue_len(&session->reorder_q));
346                         u64_stats_update_begin(&sstats->syncp);
347                         sstats->rx_oos_packets++;
348                         u64_stats_update_end(&sstats->syncp);
349                         goto out;
350                 }
351         }
352
353         __skb_queue_tail(&session->reorder_q, skb);
354
355 out:
356         spin_unlock_bh(&session->reorder_q.lock);
357 }
358
359 /* Dequeue a single skb.
360  */
361 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
362 {
363         struct l2tp_tunnel *tunnel = session->tunnel;
364         int length = L2TP_SKB_CB(skb)->length;
365         struct l2tp_stats *tstats, *sstats;
366
367         /* We're about to requeue the skb, so return resources
368          * to its current owner (a socket receive buffer).
369          */
370         skb_orphan(skb);
371
372         tstats = &tunnel->stats;
373         u64_stats_update_begin(&tstats->syncp);
374         sstats = &session->stats;
375         u64_stats_update_begin(&sstats->syncp);
376         tstats->rx_packets++;
377         tstats->rx_bytes += length;
378         sstats->rx_packets++;
379         sstats->rx_bytes += length;
380         u64_stats_update_end(&tstats->syncp);
381         u64_stats_update_end(&sstats->syncp);
382
383         if (L2TP_SKB_CB(skb)->has_seq) {
384                 /* Bump our Nr */
385                 session->nr++;
386                 if (tunnel->version == L2TP_HDR_VER_2)
387                         session->nr &= 0xffff;
388                 else
389                         session->nr &= 0xffffff;
390
391                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
392                          session->name, session->nr);
393         }
394
395         /* call private receive handler */
396         if (session->recv_skb != NULL)
397                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
398         else
399                 kfree_skb(skb);
400
401         if (session->deref)
402                 (*session->deref)(session);
403 }
404
405 /* Dequeue skbs from the session's reorder_q, subject to packet order.
406  * Skbs that have been in the queue for too long are simply discarded.
407  */
408 static void l2tp_recv_dequeue(struct l2tp_session *session)
409 {
410         struct sk_buff *skb;
411         struct sk_buff *tmp;
412         struct l2tp_stats *sstats;
413
414         /* If the pkt at the head of the queue has the nr that we
415          * expect to send up next, dequeue it and any other
416          * in-sequence packets behind it.
417          */
418 start:
419         spin_lock_bh(&session->reorder_q.lock);
420         sstats = &session->stats;
421         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
422                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
423                         u64_stats_update_begin(&sstats->syncp);
424                         sstats->rx_seq_discards++;
425                         sstats->rx_errors++;
426                         u64_stats_update_end(&sstats->syncp);
427                         l2tp_dbg(session, L2TP_MSG_SEQ,
428                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
429                                  session->name, L2TP_SKB_CB(skb)->ns,
430                                  L2TP_SKB_CB(skb)->length, session->nr,
431                                  skb_queue_len(&session->reorder_q));
432                         session->reorder_skip = 1;
433                         __skb_unlink(skb, &session->reorder_q);
434                         kfree_skb(skb);
435                         if (session->deref)
436                                 (*session->deref)(session);
437                         continue;
438                 }
439
440                 if (L2TP_SKB_CB(skb)->has_seq) {
441                         if (session->reorder_skip) {
442                                 l2tp_dbg(session, L2TP_MSG_SEQ,
443                                          "%s: advancing nr to next pkt: %u -> %u",
444                                          session->name, session->nr,
445                                          L2TP_SKB_CB(skb)->ns);
446                                 session->reorder_skip = 0;
447                                 session->nr = L2TP_SKB_CB(skb)->ns;
448                         }
449                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
450                                 l2tp_dbg(session, L2TP_MSG_SEQ,
451                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
452                                          session->name, L2TP_SKB_CB(skb)->ns,
453                                          L2TP_SKB_CB(skb)->length, session->nr,
454                                          skb_queue_len(&session->reorder_q));
455                                 goto out;
456                         }
457                 }
458                 __skb_unlink(skb, &session->reorder_q);
459
460                 /* Process the skb. We release the queue lock while we
461                  * do so to let other contexts process the queue.
462                  */
463                 spin_unlock_bh(&session->reorder_q.lock);
464                 l2tp_recv_dequeue_skb(session, skb);
465                 goto start;
466         }
467
468 out:
469         spin_unlock_bh(&session->reorder_q.lock);
470 }
471
472 static inline int l2tp_verify_udp_checksum(struct sock *sk,
473                                            struct sk_buff *skb)
474 {
475         struct udphdr *uh = udp_hdr(skb);
476         u16 ulen = ntohs(uh->len);
477         __wsum psum;
478
479         if (sk->sk_no_check || skb_csum_unnecessary(skb))
480                 return 0;
481
482 #if IS_ENABLED(CONFIG_IPV6)
483         if (sk->sk_family == PF_INET6) {
484                 if (!uh->check) {
485                         LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
486                         return 1;
487                 }
488                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
489                     !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
490                                      &ipv6_hdr(skb)->daddr, ulen,
491                                      IPPROTO_UDP, skb->csum)) {
492                         skb->ip_summed = CHECKSUM_UNNECESSARY;
493                         return 0;
494                 }
495                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
496                                                          &ipv6_hdr(skb)->daddr,
497                                                          skb->len, IPPROTO_UDP,
498                                                          0));
499         } else
500 #endif
501         {
502                 struct inet_sock *inet;
503                 if (!uh->check)
504                         return 0;
505                 inet = inet_sk(sk);
506                 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
507                                           ulen, IPPROTO_UDP, 0);
508
509                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
510                     !csum_fold(csum_add(psum, skb->csum)))
511                         return 0;
512                 skb->csum = psum;
513         }
514
515         return __skb_checksum_complete(skb);
516 }
517
518 /* Do receive processing of L2TP data frames. We handle both L2TPv2
519  * and L2TPv3 data frames here.
520  *
521  * L2TPv2 Data Message Header
522  *
523  *  0                   1                   2                   3
524  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
525  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
526  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
527  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
528  * |           Tunnel ID           |           Session ID          |
529  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
530  * |             Ns (opt)          |             Nr (opt)          |
531  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
532  * |      Offset Size (opt)        |    Offset pad... (opt)
533  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
534  *
535  * Data frames are marked by T=0. All other fields are the same as
536  * those in L2TP control frames.
537  *
538  * L2TPv3 Data Message Header
539  *
540  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
541  * |                      L2TP Session Header                      |
542  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
543  * |                      L2-Specific Sublayer                     |
544  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
545  * |                        Tunnel Payload                      ...
546  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
547  *
548  * L2TPv3 Session Header Over IP
549  *
550  *  0                   1                   2                   3
551  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
552  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
553  * |                           Session ID                          |
554  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
555  * |               Cookie (optional, maximum 64 bits)...
556  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
557  *                                                                 |
558  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
559  *
560  * L2TPv3 L2-Specific Sublayer Format
561  *
562  *  0                   1                   2                   3
563  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
564  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
565  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
566  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
567  *
568  * Cookie value, sublayer format and offset (pad) are negotiated with
569  * the peer when the session is set up. Unlike L2TPv2, we do not need
570  * to parse the packet header to determine if optional fields are
571  * present.
572  *
573  * Caller must already have parsed the frame and determined that it is
574  * a data (not control) frame before coming here. Fields up to the
575  * session-id have already been parsed and ptr points to the data
576  * after the session-id.
577  */
578 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
579                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
580                       int length, int (*payload_hook)(struct sk_buff *skb))
581 {
582         struct l2tp_tunnel *tunnel = session->tunnel;
583         int offset;
584         u32 ns, nr;
585         struct l2tp_stats *sstats = &session->stats;
586
587         /* The ref count is increased since we now hold a pointer to
588          * the session. Take care to decrement the refcnt when exiting
589          * this function from now on...
590          */
591         l2tp_session_inc_refcount(session);
592         if (session->ref)
593                 (*session->ref)(session);
594
595         /* Parse and check optional cookie */
596         if (session->peer_cookie_len > 0) {
597                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
598                         l2tp_info(tunnel, L2TP_MSG_DATA,
599                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
600                                   tunnel->name, tunnel->tunnel_id,
601                                   session->session_id);
602                         u64_stats_update_begin(&sstats->syncp);
603                         sstats->rx_cookie_discards++;
604                         u64_stats_update_end(&sstats->syncp);
605                         goto discard;
606                 }
607                 ptr += session->peer_cookie_len;
608         }
609
610         /* Handle the optional sequence numbers. Sequence numbers are
611          * in different places for L2TPv2 and L2TPv3.
612          *
613          * If we are the LAC, enable/disable sequence numbers under
614          * the control of the LNS.  If no sequence numbers present but
615          * we were expecting them, discard frame.
616          */
617         ns = nr = 0;
618         L2TP_SKB_CB(skb)->has_seq = 0;
619         if (tunnel->version == L2TP_HDR_VER_2) {
620                 if (hdrflags & L2TP_HDRFLAG_S) {
621                         ns = ntohs(*(__be16 *) ptr);
622                         ptr += 2;
623                         nr = ntohs(*(__be16 *) ptr);
624                         ptr += 2;
625
626                         /* Store L2TP info in the skb */
627                         L2TP_SKB_CB(skb)->ns = ns;
628                         L2TP_SKB_CB(skb)->has_seq = 1;
629
630                         l2tp_dbg(session, L2TP_MSG_SEQ,
631                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
632                                  session->name, ns, nr, session->nr);
633                 }
634         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
635                 u32 l2h = ntohl(*(__be32 *) ptr);
636
637                 if (l2h & 0x40000000) {
638                         ns = l2h & 0x00ffffff;
639
640                         /* Store L2TP info in the skb */
641                         L2TP_SKB_CB(skb)->ns = ns;
642                         L2TP_SKB_CB(skb)->has_seq = 1;
643
644                         l2tp_dbg(session, L2TP_MSG_SEQ,
645                                  "%s: recv data ns=%u, session nr=%u\n",
646                                  session->name, ns, session->nr);
647                 }
648         }
649
650         /* Advance past L2-specific header, if present */
651         ptr += session->l2specific_len;
652
653         if (L2TP_SKB_CB(skb)->has_seq) {
654                 /* Received a packet with sequence numbers. If we're the LNS,
655                  * check if we sre sending sequence numbers and if not,
656                  * configure it so.
657                  */
658                 if ((!session->lns_mode) && (!session->send_seq)) {
659                         l2tp_info(session, L2TP_MSG_SEQ,
660                                   "%s: requested to enable seq numbers by LNS\n",
661                                   session->name);
662                         session->send_seq = -1;
663                         l2tp_session_set_header_len(session, tunnel->version);
664                 }
665         } else {
666                 /* No sequence numbers.
667                  * If user has configured mandatory sequence numbers, discard.
668                  */
669                 if (session->recv_seq) {
670                         l2tp_warn(session, L2TP_MSG_SEQ,
671                                   "%s: recv data has no seq numbers when required. Discarding.\n",
672                                   session->name);
673                         u64_stats_update_begin(&sstats->syncp);
674                         sstats->rx_seq_discards++;
675                         u64_stats_update_end(&sstats->syncp);
676                         goto discard;
677                 }
678
679                 /* If we're the LAC and we're sending sequence numbers, the
680                  * LNS has requested that we no longer send sequence numbers.
681                  * If we're the LNS and we're sending sequence numbers, the
682                  * LAC is broken. Discard the frame.
683                  */
684                 if ((!session->lns_mode) && (session->send_seq)) {
685                         l2tp_info(session, L2TP_MSG_SEQ,
686                                   "%s: requested to disable seq numbers by LNS\n",
687                                   session->name);
688                         session->send_seq = 0;
689                         l2tp_session_set_header_len(session, tunnel->version);
690                 } else if (session->send_seq) {
691                         l2tp_warn(session, L2TP_MSG_SEQ,
692                                   "%s: recv data has no seq numbers when required. Discarding.\n",
693                                   session->name);
694                         u64_stats_update_begin(&sstats->syncp);
695                         sstats->rx_seq_discards++;
696                         u64_stats_update_end(&sstats->syncp);
697                         goto discard;
698                 }
699         }
700
701         /* Session data offset is handled differently for L2TPv2 and
702          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
703          * the header. For L2TPv3, the offset is negotiated using AVPs
704          * in the session setup control protocol.
705          */
706         if (tunnel->version == L2TP_HDR_VER_2) {
707                 /* If offset bit set, skip it. */
708                 if (hdrflags & L2TP_HDRFLAG_O) {
709                         offset = ntohs(*(__be16 *)ptr);
710                         ptr += 2 + offset;
711                 }
712         } else
713                 ptr += session->offset;
714
715         offset = ptr - optr;
716         if (!pskb_may_pull(skb, offset))
717                 goto discard;
718
719         __skb_pull(skb, offset);
720
721         /* If caller wants to process the payload before we queue the
722          * packet, do so now.
723          */
724         if (payload_hook)
725                 if ((*payload_hook)(skb))
726                         goto discard;
727
728         /* Prepare skb for adding to the session's reorder_q.  Hold
729          * packets for max reorder_timeout or 1 second if not
730          * reordering.
731          */
732         L2TP_SKB_CB(skb)->length = length;
733         L2TP_SKB_CB(skb)->expires = jiffies +
734                 (session->reorder_timeout ? session->reorder_timeout : HZ);
735
736         /* Add packet to the session's receive queue. Reordering is done here, if
737          * enabled. Saved L2TP protocol info is stored in skb->sb[].
738          */
739         if (L2TP_SKB_CB(skb)->has_seq) {
740                 if (session->reorder_timeout != 0) {
741                         /* Packet reordering enabled. Add skb to session's
742                          * reorder queue, in order of ns.
743                          */
744                         l2tp_recv_queue_skb(session, skb);
745                 } else {
746                         /* Packet reordering disabled. Discard out-of-sequence
747                          * packets
748                          */
749                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
750                                 u64_stats_update_begin(&sstats->syncp);
751                                 sstats->rx_seq_discards++;
752                                 u64_stats_update_end(&sstats->syncp);
753                                 l2tp_dbg(session, L2TP_MSG_SEQ,
754                                          "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
755                                          session->name, L2TP_SKB_CB(skb)->ns,
756                                          L2TP_SKB_CB(skb)->length, session->nr,
757                                          skb_queue_len(&session->reorder_q));
758                                 goto discard;
759                         }
760                         skb_queue_tail(&session->reorder_q, skb);
761                 }
762         } else {
763                 /* No sequence numbers. Add the skb to the tail of the
764                  * reorder queue. This ensures that it will be
765                  * delivered after all previous sequenced skbs.
766                  */
767                 skb_queue_tail(&session->reorder_q, skb);
768         }
769
770         /* Try to dequeue as many skbs from reorder_q as we can. */
771         l2tp_recv_dequeue(session);
772
773         l2tp_session_dec_refcount(session);
774
775         return;
776
777 discard:
778         u64_stats_update_begin(&sstats->syncp);
779         sstats->rx_errors++;
780         u64_stats_update_end(&sstats->syncp);
781         kfree_skb(skb);
782
783         if (session->deref)
784                 (*session->deref)(session);
785
786         l2tp_session_dec_refcount(session);
787 }
788 EXPORT_SYMBOL(l2tp_recv_common);
789
790 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
791  * here. The skb is not on a list when we get here.
792  * Returns 0 if the packet was a data packet and was successfully passed on.
793  * Returns 1 if the packet was not a good data packet and could not be
794  * forwarded.  All such packets are passed up to userspace to deal with.
795  */
796 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
797                               int (*payload_hook)(struct sk_buff *skb))
798 {
799         struct l2tp_session *session = NULL;
800         unsigned char *ptr, *optr;
801         u16 hdrflags;
802         u32 tunnel_id, session_id;
803         u16 version;
804         int length;
805         struct l2tp_stats *tstats;
806
807         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
808                 goto discard_bad_csum;
809
810         /* UDP always verifies the packet length. */
811         __skb_pull(skb, sizeof(struct udphdr));
812
813         /* Short packet? */
814         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
815                 l2tp_info(tunnel, L2TP_MSG_DATA,
816                           "%s: recv short packet (len=%d)\n",
817                           tunnel->name, skb->len);
818                 goto error;
819         }
820
821         /* Trace packet contents, if enabled */
822         if (tunnel->debug & L2TP_MSG_DATA) {
823                 length = min(32u, skb->len);
824                 if (!pskb_may_pull(skb, length))
825                         goto error;
826
827                 pr_debug("%s: recv\n", tunnel->name);
828                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
829         }
830
831         /* Point to L2TP header */
832         optr = ptr = skb->data;
833
834         /* Get L2TP header flags */
835         hdrflags = ntohs(*(__be16 *) ptr);
836
837         /* Check protocol version */
838         version = hdrflags & L2TP_HDR_VER_MASK;
839         if (version != tunnel->version) {
840                 l2tp_info(tunnel, L2TP_MSG_DATA,
841                           "%s: recv protocol version mismatch: got %d expected %d\n",
842                           tunnel->name, version, tunnel->version);
843                 goto error;
844         }
845
846         /* Get length of L2TP packet */
847         length = skb->len;
848
849         /* If type is control packet, it is handled by userspace. */
850         if (hdrflags & L2TP_HDRFLAG_T) {
851                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
852                          "%s: recv control packet, len=%d\n",
853                          tunnel->name, length);
854                 goto error;
855         }
856
857         /* Skip flags */
858         ptr += 2;
859
860         if (tunnel->version == L2TP_HDR_VER_2) {
861                 /* If length is present, skip it */
862                 if (hdrflags & L2TP_HDRFLAG_L)
863                         ptr += 2;
864
865                 /* Extract tunnel and session ID */
866                 tunnel_id = ntohs(*(__be16 *) ptr);
867                 ptr += 2;
868                 session_id = ntohs(*(__be16 *) ptr);
869                 ptr += 2;
870         } else {
871                 ptr += 2;       /* skip reserved bits */
872                 tunnel_id = tunnel->tunnel_id;
873                 session_id = ntohl(*(__be32 *) ptr);
874                 ptr += 4;
875         }
876
877         /* Find the session context */
878         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
879         if (!session || !session->recv_skb) {
880                 /* Not found? Pass to userspace to deal with */
881                 l2tp_info(tunnel, L2TP_MSG_DATA,
882                           "%s: no session found (%u/%u). Passing up.\n",
883                           tunnel->name, tunnel_id, session_id);
884                 goto error;
885         }
886
887         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
888
889         return 0;
890
891 discard_bad_csum:
892         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
893         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
894         tstats = &tunnel->stats;
895         u64_stats_update_begin(&tstats->syncp);
896         tstats->rx_errors++;
897         u64_stats_update_end(&tstats->syncp);
898         kfree_skb(skb);
899
900         return 0;
901
902 error:
903         /* Put UDP header back */
904         __skb_push(skb, sizeof(struct udphdr));
905
906         return 1;
907 }
908
909 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
910  * Return codes:
911  * 0 : success.
912  * <0: error
913  * >0: skb should be passed up to userspace as UDP.
914  */
915 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
916 {
917         struct l2tp_tunnel *tunnel;
918
919         tunnel = l2tp_sock_to_tunnel(sk);
920         if (tunnel == NULL)
921                 goto pass_up;
922
923         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
924                  tunnel->name, skb->len);
925
926         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
927                 goto pass_up_put;
928
929         sock_put(sk);
930         return 0;
931
932 pass_up_put:
933         sock_put(sk);
934 pass_up:
935         return 1;
936 }
937 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
938
939 /************************************************************************
940  * Transmit handling
941  ***********************************************************************/
942
943 /* Build an L2TP header for the session into the buffer provided.
944  */
945 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
946 {
947         struct l2tp_tunnel *tunnel = session->tunnel;
948         __be16 *bufp = buf;
949         __be16 *optr = buf;
950         u16 flags = L2TP_HDR_VER_2;
951         u32 tunnel_id = tunnel->peer_tunnel_id;
952         u32 session_id = session->peer_session_id;
953
954         if (session->send_seq)
955                 flags |= L2TP_HDRFLAG_S;
956
957         /* Setup L2TP header. */
958         *bufp++ = htons(flags);
959         *bufp++ = htons(tunnel_id);
960         *bufp++ = htons(session_id);
961         if (session->send_seq) {
962                 *bufp++ = htons(session->ns);
963                 *bufp++ = 0;
964                 session->ns++;
965                 session->ns &= 0xffff;
966                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
967                          session->name, session->ns);
968         }
969
970         return bufp - optr;
971 }
972
973 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
974 {
975         struct l2tp_tunnel *tunnel = session->tunnel;
976         char *bufp = buf;
977         char *optr = bufp;
978
979         /* Setup L2TP header. The header differs slightly for UDP and
980          * IP encapsulations. For UDP, there is 4 bytes of flags.
981          */
982         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
983                 u16 flags = L2TP_HDR_VER_3;
984                 *((__be16 *) bufp) = htons(flags);
985                 bufp += 2;
986                 *((__be16 *) bufp) = 0;
987                 bufp += 2;
988         }
989
990         *((__be32 *) bufp) = htonl(session->peer_session_id);
991         bufp += 4;
992         if (session->cookie_len) {
993                 memcpy(bufp, &session->cookie[0], session->cookie_len);
994                 bufp += session->cookie_len;
995         }
996         if (session->l2specific_len) {
997                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
998                         u32 l2h = 0;
999                         if (session->send_seq) {
1000                                 l2h = 0x40000000 | session->ns;
1001                                 session->ns++;
1002                                 session->ns &= 0xffffff;
1003                                 l2tp_dbg(session, L2TP_MSG_SEQ,
1004                                          "%s: updated ns to %u\n",
1005                                          session->name, session->ns);
1006                         }
1007
1008                         *((__be32 *) bufp) = htonl(l2h);
1009                 }
1010                 bufp += session->l2specific_len;
1011         }
1012         if (session->offset)
1013                 bufp += session->offset;
1014
1015         return bufp - optr;
1016 }
1017
1018 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1019                           struct flowi *fl, size_t data_len)
1020 {
1021         struct l2tp_tunnel *tunnel = session->tunnel;
1022         unsigned int len = skb->len;
1023         int error;
1024         struct l2tp_stats *tstats, *sstats;
1025
1026         /* Debug */
1027         if (session->send_seq)
1028                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1029                          session->name, data_len, session->ns - 1);
1030         else
1031                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1032                          session->name, data_len);
1033
1034         if (session->debug & L2TP_MSG_DATA) {
1035                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1036                 unsigned char *datap = skb->data + uhlen;
1037
1038                 pr_debug("%s: xmit\n", session->name);
1039                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1040                                      datap, min_t(size_t, 32, len - uhlen));
1041         }
1042
1043         /* Queue the packet to IP for output */
1044         skb->local_df = 1;
1045 #if IS_ENABLED(CONFIG_IPV6)
1046         if (skb->sk->sk_family == PF_INET6)
1047                 error = inet6_csk_xmit(skb, NULL);
1048         else
1049 #endif
1050                 error = ip_queue_xmit(skb, fl);
1051
1052         /* Update stats */
1053         tstats = &tunnel->stats;
1054         u64_stats_update_begin(&tstats->syncp);
1055         sstats = &session->stats;
1056         u64_stats_update_begin(&sstats->syncp);
1057         if (error >= 0) {
1058                 tstats->tx_packets++;
1059                 tstats->tx_bytes += len;
1060                 sstats->tx_packets++;
1061                 sstats->tx_bytes += len;
1062         } else {
1063                 tstats->tx_errors++;
1064                 sstats->tx_errors++;
1065         }
1066         u64_stats_update_end(&tstats->syncp);
1067         u64_stats_update_end(&sstats->syncp);
1068
1069         return 0;
1070 }
1071
1072 /* Automatically called when the skb is freed.
1073  */
1074 static void l2tp_sock_wfree(struct sk_buff *skb)
1075 {
1076         sock_put(skb->sk);
1077 }
1078
1079 /* For data skbs that we transmit, we associate with the tunnel socket
1080  * but don't do accounting.
1081  */
1082 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1083 {
1084         sock_hold(sk);
1085         skb->sk = sk;
1086         skb->destructor = l2tp_sock_wfree;
1087 }
1088
1089 #if IS_ENABLED(CONFIG_IPV6)
1090 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1091                                 int udp_len)
1092 {
1093         struct ipv6_pinfo *np = inet6_sk(sk);
1094         struct udphdr *uh = udp_hdr(skb);
1095
1096         if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1097             !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1098                 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1099                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1100                 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1101                                             IPPROTO_UDP, csum);
1102                 if (uh->check == 0)
1103                         uh->check = CSUM_MANGLED_0;
1104         } else {
1105                 skb->ip_summed = CHECKSUM_PARTIAL;
1106                 skb->csum_start = skb_transport_header(skb) - skb->head;
1107                 skb->csum_offset = offsetof(struct udphdr, check);
1108                 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1109                                              udp_len, IPPROTO_UDP, 0);
1110         }
1111 }
1112 #endif
1113
1114 /* If caller requires the skb to have a ppp header, the header must be
1115  * inserted in the skb data before calling this function.
1116  */
1117 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1118 {
1119         int data_len = skb->len;
1120         struct l2tp_tunnel *tunnel = session->tunnel;
1121         struct sock *sk = tunnel->sock;
1122         struct flowi *fl;
1123         struct udphdr *uh;
1124         struct inet_sock *inet;
1125         __wsum csum;
1126         int old_headroom;
1127         int new_headroom;
1128         int headroom;
1129         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1130         int udp_len;
1131         int ret = NET_XMIT_SUCCESS;
1132
1133         /* Check that there's enough headroom in the skb to insert IP,
1134          * UDP and L2TP headers. If not enough, expand it to
1135          * make room. Adjust truesize.
1136          */
1137         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1138                 uhlen + hdr_len;
1139         old_headroom = skb_headroom(skb);
1140         if (skb_cow_head(skb, headroom)) {
1141                 kfree_skb(skb);
1142                 return NET_XMIT_DROP;
1143         }
1144
1145         new_headroom = skb_headroom(skb);
1146         skb_orphan(skb);
1147         skb->truesize += new_headroom - old_headroom;
1148
1149         /* Setup L2TP header */
1150         session->build_header(session, __skb_push(skb, hdr_len));
1151
1152         /* Reset skb netfilter state */
1153         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1154         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1155                               IPSKB_REROUTED);
1156         nf_reset(skb);
1157
1158         bh_lock_sock(sk);
1159         if (sock_owned_by_user(sk)) {
1160                 kfree_skb(skb);
1161                 ret = NET_XMIT_DROP;
1162                 goto out_unlock;
1163         }
1164
1165         /* Get routing info from the tunnel socket */
1166         skb_dst_drop(skb);
1167         skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1168
1169         inet = inet_sk(sk);
1170         fl = &inet->cork.fl;
1171         switch (tunnel->encap) {
1172         case L2TP_ENCAPTYPE_UDP:
1173                 /* Setup UDP header */
1174                 __skb_push(skb, sizeof(*uh));
1175                 skb_reset_transport_header(skb);
1176                 uh = udp_hdr(skb);
1177                 uh->source = inet->inet_sport;
1178                 uh->dest = inet->inet_dport;
1179                 udp_len = uhlen + hdr_len + data_len;
1180                 uh->len = htons(udp_len);
1181                 uh->check = 0;
1182
1183                 /* Calculate UDP checksum if configured to do so */
1184 #if IS_ENABLED(CONFIG_IPV6)
1185                 if (sk->sk_family == PF_INET6)
1186                         l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1187                 else
1188 #endif
1189                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1190                         skb->ip_summed = CHECKSUM_NONE;
1191                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1192                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1193                         skb->ip_summed = CHECKSUM_COMPLETE;
1194                         csum = skb_checksum(skb, 0, udp_len, 0);
1195                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1196                                                       inet->inet_daddr,
1197                                                       udp_len, IPPROTO_UDP, csum);
1198                         if (uh->check == 0)
1199                                 uh->check = CSUM_MANGLED_0;
1200                 } else {
1201                         skb->ip_summed = CHECKSUM_PARTIAL;
1202                         skb->csum_start = skb_transport_header(skb) - skb->head;
1203                         skb->csum_offset = offsetof(struct udphdr, check);
1204                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1205                                                        inet->inet_daddr,
1206                                                        udp_len, IPPROTO_UDP, 0);
1207                 }
1208                 break;
1209
1210         case L2TP_ENCAPTYPE_IP:
1211                 break;
1212         }
1213
1214         l2tp_skb_set_owner_w(skb, sk);
1215
1216         l2tp_xmit_core(session, skb, fl, data_len);
1217 out_unlock:
1218         bh_unlock_sock(sk);
1219
1220         return ret;
1221 }
1222 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1223
1224 /*****************************************************************************
1225  * Tinnel and session create/destroy.
1226  *****************************************************************************/
1227
1228 /* Tunnel socket destruct hook.
1229  * The tunnel context is deleted only when all session sockets have been
1230  * closed.
1231  */
1232 static void l2tp_tunnel_destruct(struct sock *sk)
1233 {
1234         struct l2tp_tunnel *tunnel;
1235
1236         tunnel = sk->sk_user_data;
1237         if (tunnel == NULL)
1238                 goto end;
1239
1240         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1241
1242         /* Close all sessions */
1243         l2tp_tunnel_closeall(tunnel);
1244
1245         switch (tunnel->encap) {
1246         case L2TP_ENCAPTYPE_UDP:
1247                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1248                 (udp_sk(sk))->encap_type = 0;
1249                 (udp_sk(sk))->encap_rcv = NULL;
1250                 break;
1251         case L2TP_ENCAPTYPE_IP:
1252                 break;
1253         }
1254
1255         /* Remove hooks into tunnel socket */
1256         tunnel->sock = NULL;
1257         sk->sk_destruct = tunnel->old_sk_destruct;
1258         sk->sk_user_data = NULL;
1259
1260         /* Call the original destructor */
1261         if (sk->sk_destruct)
1262                 (*sk->sk_destruct)(sk);
1263
1264         /* We're finished with the socket */
1265         l2tp_tunnel_dec_refcount(tunnel);
1266
1267 end:
1268         return;
1269 }
1270
1271 /* When the tunnel is closed, all the attached sessions need to go too.
1272  */
1273 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1274 {
1275         int hash;
1276         struct hlist_node *walk;
1277         struct hlist_node *tmp;
1278         struct l2tp_session *session;
1279
1280         BUG_ON(tunnel == NULL);
1281
1282         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1283                   tunnel->name);
1284
1285         write_lock_bh(&tunnel->hlist_lock);
1286         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1287 again:
1288                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1289                         session = hlist_entry(walk, struct l2tp_session, hlist);
1290
1291                         l2tp_info(session, L2TP_MSG_CONTROL,
1292                                   "%s: closing session\n", session->name);
1293
1294                         hlist_del_init(&session->hlist);
1295
1296                         /* Since we should hold the sock lock while
1297                          * doing any unbinding, we need to release the
1298                          * lock we're holding before taking that lock.
1299                          * Hold a reference to the sock so it doesn't
1300                          * disappear as we're jumping between locks.
1301                          */
1302                         if (session->ref != NULL)
1303                                 (*session->ref)(session);
1304
1305                         write_unlock_bh(&tunnel->hlist_lock);
1306
1307                         if (tunnel->version != L2TP_HDR_VER_2) {
1308                                 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1309
1310                                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1311                                 hlist_del_init_rcu(&session->global_hlist);
1312                                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1313                                 synchronize_rcu();
1314                         }
1315
1316                         if (session->session_close != NULL)
1317                                 (*session->session_close)(session);
1318
1319                         if (session->deref != NULL)
1320                                 (*session->deref)(session);
1321
1322                         write_lock_bh(&tunnel->hlist_lock);
1323
1324                         /* Now restart from the beginning of this hash
1325                          * chain.  We always remove a session from the
1326                          * list so we are guaranteed to make forward
1327                          * progress.
1328                          */
1329                         goto again;
1330                 }
1331         }
1332         write_unlock_bh(&tunnel->hlist_lock);
1333 }
1334
1335 /* Really kill the tunnel.
1336  * Come here only when all sessions have been cleared from the tunnel.
1337  */
1338 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1339 {
1340         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1341
1342         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1343         BUG_ON(tunnel->sock != NULL);
1344
1345         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1346
1347         /* Remove from tunnel list */
1348         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1349         list_del_rcu(&tunnel->list);
1350         kfree_rcu(tunnel, rcu);
1351         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1352
1353         atomic_dec(&l2tp_tunnel_count);
1354 }
1355
1356 /* Create a socket for the tunnel, if one isn't set up by
1357  * userspace. This is used for static tunnels where there is no
1358  * managing L2TP daemon.
1359  */
1360 static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1361 {
1362         int err = -EINVAL;
1363         struct sockaddr_in udp_addr;
1364 #if IS_ENABLED(CONFIG_IPV6)
1365         struct sockaddr_in6 udp6_addr;
1366         struct sockaddr_l2tpip6 ip6_addr;
1367 #endif
1368         struct sockaddr_l2tpip ip_addr;
1369         struct socket *sock = NULL;
1370
1371         switch (cfg->encap) {
1372         case L2TP_ENCAPTYPE_UDP:
1373 #if IS_ENABLED(CONFIG_IPV6)
1374                 if (cfg->local_ip6 && cfg->peer_ip6) {
1375                         err = sock_create(AF_INET6, SOCK_DGRAM, 0, sockp);
1376                         if (err < 0)
1377                                 goto out;
1378
1379                         sock = *sockp;
1380
1381                         memset(&udp6_addr, 0, sizeof(udp6_addr));
1382                         udp6_addr.sin6_family = AF_INET6;
1383                         memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1384                                sizeof(udp6_addr.sin6_addr));
1385                         udp6_addr.sin6_port = htons(cfg->local_udp_port);
1386                         err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1387                                           sizeof(udp6_addr));
1388                         if (err < 0)
1389                                 goto out;
1390
1391                         udp6_addr.sin6_family = AF_INET6;
1392                         memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1393                                sizeof(udp6_addr.sin6_addr));
1394                         udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1395                         err = kernel_connect(sock,
1396                                              (struct sockaddr *) &udp6_addr,
1397                                              sizeof(udp6_addr), 0);
1398                         if (err < 0)
1399                                 goto out;
1400                 } else
1401 #endif
1402                 {
1403                         err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1404                         if (err < 0)
1405                                 goto out;
1406
1407                         sock = *sockp;
1408
1409                         memset(&udp_addr, 0, sizeof(udp_addr));
1410                         udp_addr.sin_family = AF_INET;
1411                         udp_addr.sin_addr = cfg->local_ip;
1412                         udp_addr.sin_port = htons(cfg->local_udp_port);
1413                         err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1414                                           sizeof(udp_addr));
1415                         if (err < 0)
1416                                 goto out;
1417
1418                         udp_addr.sin_family = AF_INET;
1419                         udp_addr.sin_addr = cfg->peer_ip;
1420                         udp_addr.sin_port = htons(cfg->peer_udp_port);
1421                         err = kernel_connect(sock,
1422                                              (struct sockaddr *) &udp_addr,
1423                                              sizeof(udp_addr), 0);
1424                         if (err < 0)
1425                                 goto out;
1426                 }
1427
1428                 if (!cfg->use_udp_checksums)
1429                         sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1430
1431                 break;
1432
1433         case L2TP_ENCAPTYPE_IP:
1434 #if IS_ENABLED(CONFIG_IPV6)
1435                 if (cfg->local_ip6 && cfg->peer_ip6) {
1436                         err = sock_create(AF_INET6, SOCK_DGRAM, IPPROTO_L2TP,
1437                                           sockp);
1438                         if (err < 0)
1439                                 goto out;
1440
1441                         sock = *sockp;
1442
1443                         memset(&ip6_addr, 0, sizeof(ip6_addr));
1444                         ip6_addr.l2tp_family = AF_INET6;
1445                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1446                                sizeof(ip6_addr.l2tp_addr));
1447                         ip6_addr.l2tp_conn_id = tunnel_id;
1448                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1449                                           sizeof(ip6_addr));
1450                         if (err < 0)
1451                                 goto out;
1452
1453                         ip6_addr.l2tp_family = AF_INET6;
1454                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1455                                sizeof(ip6_addr.l2tp_addr));
1456                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1457                         err = kernel_connect(sock,
1458                                              (struct sockaddr *) &ip6_addr,
1459                                              sizeof(ip6_addr), 0);
1460                         if (err < 0)
1461                                 goto out;
1462                 } else
1463 #endif
1464                 {
1465                         err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP,
1466                                           sockp);
1467                         if (err < 0)
1468                                 goto out;
1469
1470                         sock = *sockp;
1471
1472                         memset(&ip_addr, 0, sizeof(ip_addr));
1473                         ip_addr.l2tp_family = AF_INET;
1474                         ip_addr.l2tp_addr = cfg->local_ip;
1475                         ip_addr.l2tp_conn_id = tunnel_id;
1476                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1477                                           sizeof(ip_addr));
1478                         if (err < 0)
1479                                 goto out;
1480
1481                         ip_addr.l2tp_family = AF_INET;
1482                         ip_addr.l2tp_addr = cfg->peer_ip;
1483                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1484                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1485                                              sizeof(ip_addr), 0);
1486                         if (err < 0)
1487                                 goto out;
1488                 }
1489                 break;
1490
1491         default:
1492                 goto out;
1493         }
1494
1495 out:
1496         if ((err < 0) && sock) {
1497                 sock_release(sock);
1498                 *sockp = NULL;
1499         }
1500
1501         return err;
1502 }
1503
1504 static struct lock_class_key l2tp_socket_class;
1505
1506 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)
1507 {
1508         struct l2tp_tunnel *tunnel = NULL;
1509         int err;
1510         struct socket *sock = NULL;
1511         struct sock *sk = NULL;
1512         struct l2tp_net *pn;
1513         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1514
1515         /* Get the tunnel socket from the fd, which was opened by
1516          * the userspace L2TP daemon. If not specified, create a
1517          * kernel socket.
1518          */
1519         if (fd < 0) {
1520                 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1521                 if (err < 0)
1522                         goto err;
1523         } else {
1524                 err = -EBADF;
1525                 sock = sockfd_lookup(fd, &err);
1526                 if (!sock) {
1527                         pr_err("tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1528                                tunnel_id, fd, err);
1529                         goto err;
1530                 }
1531         }
1532
1533         sk = sock->sk;
1534
1535         if (cfg != NULL)
1536                 encap = cfg->encap;
1537
1538         /* Quick sanity checks */
1539         switch (encap) {
1540         case L2TP_ENCAPTYPE_UDP:
1541                 err = -EPROTONOSUPPORT;
1542                 if (sk->sk_protocol != IPPROTO_UDP) {
1543                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1544                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1545                         goto err;
1546                 }
1547                 break;
1548         case L2TP_ENCAPTYPE_IP:
1549                 err = -EPROTONOSUPPORT;
1550                 if (sk->sk_protocol != IPPROTO_L2TP) {
1551                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1552                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1553                         goto err;
1554                 }
1555                 break;
1556         }
1557
1558         /* Check if this socket has already been prepped */
1559         tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1560         if (tunnel != NULL) {
1561                 /* This socket has already been prepped */
1562                 err = -EBUSY;
1563                 goto err;
1564         }
1565
1566         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1567         if (tunnel == NULL) {
1568                 err = -ENOMEM;
1569                 goto err;
1570         }
1571
1572         tunnel->version = version;
1573         tunnel->tunnel_id = tunnel_id;
1574         tunnel->peer_tunnel_id = peer_tunnel_id;
1575         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1576
1577         tunnel->magic = L2TP_TUNNEL_MAGIC;
1578         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1579         rwlock_init(&tunnel->hlist_lock);
1580
1581         /* The net we belong to */
1582         tunnel->l2tp_net = net;
1583         pn = l2tp_pernet(net);
1584
1585         if (cfg != NULL)
1586                 tunnel->debug = cfg->debug;
1587
1588         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1589         tunnel->encap = encap;
1590         if (encap == L2TP_ENCAPTYPE_UDP) {
1591                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1592                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1593                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1594 #if IS_ENABLED(CONFIG_IPV6)
1595                 if (sk->sk_family == PF_INET6)
1596                         udpv6_encap_enable();
1597                 else
1598 #endif
1599                 udp_encap_enable();
1600         }
1601
1602         sk->sk_user_data = tunnel;
1603
1604         /* Hook on the tunnel socket destructor so that we can cleanup
1605          * if the tunnel socket goes away.
1606          */
1607         tunnel->old_sk_destruct = sk->sk_destruct;
1608         sk->sk_destruct = &l2tp_tunnel_destruct;
1609         tunnel->sock = sk;
1610         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1611
1612         sk->sk_allocation = GFP_ATOMIC;
1613
1614         /* Add tunnel to our list */
1615         INIT_LIST_HEAD(&tunnel->list);
1616         atomic_inc(&l2tp_tunnel_count);
1617
1618         /* Bump the reference count. The tunnel context is deleted
1619          * only when this drops to zero. Must be done before list insertion
1620          */
1621         l2tp_tunnel_inc_refcount(tunnel);
1622         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1623         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1624         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1625
1626         err = 0;
1627 err:
1628         if (tunnelp)
1629                 *tunnelp = tunnel;
1630
1631         /* If tunnel's socket was created by the kernel, it doesn't
1632          *  have a file.
1633          */
1634         if (sock && sock->file)
1635                 sockfd_put(sock);
1636
1637         return err;
1638 }
1639 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1640
1641 /* This function is used by the netlink TUNNEL_DELETE command.
1642  */
1643 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1644 {
1645         int err = 0;
1646         struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
1647
1648         /* Force the tunnel socket to close. This will eventually
1649          * cause the tunnel to be deleted via the normal socket close
1650          * mechanisms when userspace closes the tunnel socket.
1651          */
1652         if (sock != NULL) {
1653                 err = inet_shutdown(sock, 2);
1654
1655                 /* If the tunnel's socket was created by the kernel,
1656                  * close the socket here since the socket was not
1657                  * created by userspace.
1658                  */
1659                 if (sock->file == NULL)
1660                         err = inet_release(sock);
1661         }
1662
1663         return err;
1664 }
1665 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1666
1667 /* Really kill the session.
1668  */
1669 void l2tp_session_free(struct l2tp_session *session)
1670 {
1671         struct l2tp_tunnel *tunnel;
1672
1673         BUG_ON(atomic_read(&session->ref_count) != 0);
1674
1675         tunnel = session->tunnel;
1676         if (tunnel != NULL) {
1677                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1678
1679                 /* Delete the session from the hash */
1680                 write_lock_bh(&tunnel->hlist_lock);
1681                 hlist_del_init(&session->hlist);
1682                 write_unlock_bh(&tunnel->hlist_lock);
1683
1684                 /* Unlink from the global hash if not L2TPv2 */
1685                 if (tunnel->version != L2TP_HDR_VER_2) {
1686                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1687
1688                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1689                         hlist_del_init_rcu(&session->global_hlist);
1690                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1691                         synchronize_rcu();
1692                 }
1693
1694                 if (session->session_id != 0)
1695                         atomic_dec(&l2tp_session_count);
1696
1697                 sock_put(tunnel->sock);
1698
1699                 /* This will delete the tunnel context if this
1700                  * is the last session on the tunnel.
1701                  */
1702                 session->tunnel = NULL;
1703                 l2tp_tunnel_dec_refcount(tunnel);
1704         }
1705
1706         kfree(session);
1707
1708         return;
1709 }
1710 EXPORT_SYMBOL_GPL(l2tp_session_free);
1711
1712 /* This function is used by the netlink SESSION_DELETE command and by
1713    pseudowire modules.
1714  */
1715 int l2tp_session_delete(struct l2tp_session *session)
1716 {
1717         if (session->session_close != NULL)
1718                 (*session->session_close)(session);
1719
1720         l2tp_session_dec_refcount(session);
1721
1722         return 0;
1723 }
1724 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1725
1726
1727 /* We come here whenever a session's send_seq, cookie_len or
1728  * l2specific_len parameters are set.
1729  */
1730 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1731 {
1732         if (version == L2TP_HDR_VER_2) {
1733                 session->hdr_len = 6;
1734                 if (session->send_seq)
1735                         session->hdr_len += 4;
1736         } else {
1737                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1738                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1739                         session->hdr_len += 4;
1740         }
1741
1742 }
1743
1744 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)
1745 {
1746         struct l2tp_session *session;
1747
1748         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1749         if (session != NULL) {
1750                 session->magic = L2TP_SESSION_MAGIC;
1751                 session->tunnel = tunnel;
1752
1753                 session->session_id = session_id;
1754                 session->peer_session_id = peer_session_id;
1755                 session->nr = 0;
1756
1757                 sprintf(&session->name[0], "sess %u/%u",
1758                         tunnel->tunnel_id, session->session_id);
1759
1760                 skb_queue_head_init(&session->reorder_q);
1761
1762                 INIT_HLIST_NODE(&session->hlist);
1763                 INIT_HLIST_NODE(&session->global_hlist);
1764
1765                 /* Inherit debug options from tunnel */
1766                 session->debug = tunnel->debug;
1767
1768                 if (cfg) {
1769                         session->pwtype = cfg->pw_type;
1770                         session->debug = cfg->debug;
1771                         session->mtu = cfg->mtu;
1772                         session->mru = cfg->mru;
1773                         session->send_seq = cfg->send_seq;
1774                         session->recv_seq = cfg->recv_seq;
1775                         session->lns_mode = cfg->lns_mode;
1776                         session->reorder_timeout = cfg->reorder_timeout;
1777                         session->offset = cfg->offset;
1778                         session->l2specific_type = cfg->l2specific_type;
1779                         session->l2specific_len = cfg->l2specific_len;
1780                         session->cookie_len = cfg->cookie_len;
1781                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1782                         session->peer_cookie_len = cfg->peer_cookie_len;
1783                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1784                 }
1785
1786                 if (tunnel->version == L2TP_HDR_VER_2)
1787                         session->build_header = l2tp_build_l2tpv2_header;
1788                 else
1789                         session->build_header = l2tp_build_l2tpv3_header;
1790
1791                 l2tp_session_set_header_len(session, tunnel->version);
1792
1793                 /* Bump the reference count. The session context is deleted
1794                  * only when this drops to zero.
1795                  */
1796                 l2tp_session_inc_refcount(session);
1797                 l2tp_tunnel_inc_refcount(tunnel);
1798
1799                 /* Ensure tunnel socket isn't deleted */
1800                 sock_hold(tunnel->sock);
1801
1802                 /* Add session to the tunnel's hash list */
1803                 write_lock_bh(&tunnel->hlist_lock);
1804                 hlist_add_head(&session->hlist,
1805                                l2tp_session_id_hash(tunnel, session_id));
1806                 write_unlock_bh(&tunnel->hlist_lock);
1807
1808                 /* And to the global session list if L2TPv3 */
1809                 if (tunnel->version != L2TP_HDR_VER_2) {
1810                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1811
1812                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1813                         hlist_add_head_rcu(&session->global_hlist,
1814                                            l2tp_session_id_hash_2(pn, session_id));
1815                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1816                 }
1817
1818                 /* Ignore management session in session count value */
1819                 if (session->session_id != 0)
1820                         atomic_inc(&l2tp_session_count);
1821         }
1822
1823         return session;
1824 }
1825 EXPORT_SYMBOL_GPL(l2tp_session_create);
1826
1827 /*****************************************************************************
1828  * Init and cleanup
1829  *****************************************************************************/
1830
1831 static __net_init int l2tp_init_net(struct net *net)
1832 {
1833         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1834         int hash;
1835
1836         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1837         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1838
1839         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1840                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1841
1842         spin_lock_init(&pn->l2tp_session_hlist_lock);
1843
1844         return 0;
1845 }
1846
1847 static struct pernet_operations l2tp_net_ops = {
1848         .init = l2tp_init_net,
1849         .id   = &l2tp_net_id,
1850         .size = sizeof(struct l2tp_net),
1851 };
1852
1853 static int __init l2tp_init(void)
1854 {
1855         int rc = 0;
1856
1857         rc = register_pernet_device(&l2tp_net_ops);
1858         if (rc)
1859                 goto out;
1860
1861         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1862
1863 out:
1864         return rc;
1865 }
1866
1867 static void __exit l2tp_exit(void)
1868 {
1869         unregister_pernet_device(&l2tp_net_ops);
1870 }
1871
1872 module_init(l2tp_init);
1873 module_exit(l2tp_exit);
1874
1875 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1876 MODULE_DESCRIPTION("L2TP core");
1877 MODULE_LICENSE("GPL");
1878 MODULE_VERSION(L2TP_DRV_VERSION);
1879