fbd1f2119fe9de42906779cd8370e3138cf1f15b
[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 #include <linux/module.h>
22 #include <linux/string.h>
23 #include <linux/list.h>
24 #include <linux/uaccess.h>
25
26 #include <linux/kernel.h>
27 #include <linux/spinlock.h>
28 #include <linux/kthread.h>
29 #include <linux/sched.h>
30 #include <linux/slab.h>
31 #include <linux/errno.h>
32 #include <linux/jiffies.h>
33
34 #include <linux/netdevice.h>
35 #include <linux/net.h>
36 #include <linux/inetdevice.h>
37 #include <linux/skbuff.h>
38 #include <linux/init.h>
39 #include <linux/in.h>
40 #include <linux/ip.h>
41 #include <linux/udp.h>
42 #include <linux/l2tp.h>
43 #include <linux/hash.h>
44 #include <linux/sort.h>
45 #include <linux/file.h>
46 #include <linux/nsproxy.h>
47 #include <net/net_namespace.h>
48 #include <net/netns/generic.h>
49 #include <net/dst.h>
50 #include <net/ip.h>
51 #include <net/udp.h>
52 #include <net/inet_common.h>
53 #include <net/xfrm.h>
54 #include <net/protocol.h>
55
56 #include <asm/byteorder.h>
57 #include <asm/atomic.h>
58
59 #include "l2tp_core.h"
60
61 #define L2TP_DRV_VERSION        "V2.0"
62
63 /* L2TP header constants */
64 #define L2TP_HDRFLAG_T     0x8000
65 #define L2TP_HDRFLAG_L     0x4000
66 #define L2TP_HDRFLAG_S     0x0800
67 #define L2TP_HDRFLAG_O     0x0200
68 #define L2TP_HDRFLAG_P     0x0100
69
70 #define L2TP_HDR_VER_MASK  0x000F
71 #define L2TP_HDR_VER_2     0x0002
72 #define L2TP_HDR_VER_3     0x0003
73
74 /* L2TPv3 default L2-specific sublayer */
75 #define L2TP_SLFLAG_S      0x40000000
76 #define L2TP_SL_SEQ_MASK   0x00ffffff
77
78 #define L2TP_HDR_SIZE_SEQ               10
79 #define L2TP_HDR_SIZE_NOSEQ             6
80
81 /* Default trace flags */
82 #define L2TP_DEFAULT_DEBUG_FLAGS        0
83
84 #define PRINTK(_mask, _type, _lvl, _fmt, args...)                       \
85         do {                                                            \
86                 if ((_mask) & (_type))                                  \
87                         printk(_lvl "L2TP: " _fmt, ##args);             \
88         } while (0)
89
90 /* Private data stored for received packets in the skb.
91  */
92 struct l2tp_skb_cb {
93         u32                     ns;
94         u16                     has_seq;
95         u16                     length;
96         unsigned long           expires;
97 };
98
99 #define L2TP_SKB_CB(skb)        ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
100
101 static atomic_t l2tp_tunnel_count;
102 static atomic_t l2tp_session_count;
103
104 /* per-net private data for this module */
105 static unsigned int l2tp_net_id;
106 struct l2tp_net {
107         struct list_head l2tp_tunnel_list;
108         rwlock_t l2tp_tunnel_list_lock;
109         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
110         rwlock_t l2tp_session_hlist_lock;
111 };
112
113 static inline struct l2tp_net *l2tp_pernet(struct net *net)
114 {
115         BUG_ON(!net);
116
117         return net_generic(net, l2tp_net_id);
118 }
119
120 /* Session hash global list for L2TPv3.
121  * The session_id SHOULD be random according to RFC3931, but several
122  * L2TP implementations use incrementing session_ids.  So we do a real
123  * hash on the session_id, rather than a simple bitmask.
124  */
125 static inline struct hlist_head *
126 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
127 {
128         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
129
130 }
131
132 /* Lookup a session by id in the global session list
133  */
134 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
135 {
136         struct l2tp_net *pn = l2tp_pernet(net);
137         struct hlist_head *session_list =
138                 l2tp_session_id_hash_2(pn, session_id);
139         struct l2tp_session *session;
140         struct hlist_node *walk;
141
142         read_lock_bh(&pn->l2tp_session_hlist_lock);
143         hlist_for_each_entry(session, walk, session_list, global_hlist) {
144                 if (session->session_id == session_id) {
145                         read_unlock_bh(&pn->l2tp_session_hlist_lock);
146                         return session;
147                 }
148         }
149         read_unlock_bh(&pn->l2tp_session_hlist_lock);
150
151         return NULL;
152 }
153
154 /* Session hash list.
155  * The session_id SHOULD be random according to RFC2661, but several
156  * L2TP implementations (Cisco and Microsoft) use incrementing
157  * session_ids.  So we do a real hash on the session_id, rather than a
158  * simple bitmask.
159  */
160 static inline struct hlist_head *
161 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
162 {
163         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
164 }
165
166 /* Lookup a session by id
167  */
168 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
169 {
170         struct hlist_head *session_list;
171         struct l2tp_session *session;
172         struct hlist_node *walk;
173
174         /* In L2TPv3, session_ids are unique over all tunnels and we
175          * sometimes need to look them up before we know the
176          * tunnel.
177          */
178         if (tunnel == NULL)
179                 return l2tp_session_find_2(net, session_id);
180
181         session_list = l2tp_session_id_hash(tunnel, session_id);
182         read_lock_bh(&tunnel->hlist_lock);
183         hlist_for_each_entry(session, walk, session_list, hlist) {
184                 if (session->session_id == session_id) {
185                         read_unlock_bh(&tunnel->hlist_lock);
186                         return session;
187                 }
188         }
189         read_unlock_bh(&tunnel->hlist_lock);
190
191         return NULL;
192 }
193 EXPORT_SYMBOL_GPL(l2tp_session_find);
194
195 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
196 {
197         int hash;
198         struct hlist_node *walk;
199         struct l2tp_session *session;
200         int count = 0;
201
202         read_lock_bh(&tunnel->hlist_lock);
203         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
204                 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
205                         if (++count > nth) {
206                                 read_unlock_bh(&tunnel->hlist_lock);
207                                 return session;
208                         }
209                 }
210         }
211
212         read_unlock_bh(&tunnel->hlist_lock);
213
214         return NULL;
215 }
216 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
217
218 /* Lookup a session by interface name.
219  * This is very inefficient but is only used by management interfaces.
220  */
221 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
222 {
223         struct l2tp_net *pn = l2tp_pernet(net);
224         int hash;
225         struct hlist_node *walk;
226         struct l2tp_session *session;
227
228         read_lock_bh(&pn->l2tp_session_hlist_lock);
229         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
230                 hlist_for_each_entry(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
231                         if (!strcmp(session->ifname, ifname)) {
232                                 read_unlock_bh(&pn->l2tp_session_hlist_lock);
233                                 return session;
234                         }
235                 }
236         }
237
238         read_unlock_bh(&pn->l2tp_session_hlist_lock);
239
240         return NULL;
241 }
242 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
243
244 /* Lookup a tunnel by id
245  */
246 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
247 {
248         struct l2tp_tunnel *tunnel;
249         struct l2tp_net *pn = l2tp_pernet(net);
250
251         read_lock_bh(&pn->l2tp_tunnel_list_lock);
252         list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
253                 if (tunnel->tunnel_id == tunnel_id) {
254                         read_unlock_bh(&pn->l2tp_tunnel_list_lock);
255                         return tunnel;
256                 }
257         }
258         read_unlock_bh(&pn->l2tp_tunnel_list_lock);
259
260         return NULL;
261 }
262 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
263
264 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
265 {
266         struct l2tp_net *pn = l2tp_pernet(net);
267         struct l2tp_tunnel *tunnel;
268         int count = 0;
269
270         read_lock_bh(&pn->l2tp_tunnel_list_lock);
271         list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
272                 if (++count > nth) {
273                         read_unlock_bh(&pn->l2tp_tunnel_list_lock);
274                         return tunnel;
275                 }
276         }
277
278         read_unlock_bh(&pn->l2tp_tunnel_list_lock);
279
280         return NULL;
281 }
282 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
283
284 /*****************************************************************************
285  * Receive data handling
286  *****************************************************************************/
287
288 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
289  * number.
290  */
291 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
292 {
293         struct sk_buff *skbp;
294         struct sk_buff *tmp;
295         u32 ns = L2TP_SKB_CB(skb)->ns;
296
297         spin_lock_bh(&session->reorder_q.lock);
298         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
299                 if (L2TP_SKB_CB(skbp)->ns > ns) {
300                         __skb_queue_before(&session->reorder_q, skbp, skb);
301                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
302                                "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
303                                session->name, ns, L2TP_SKB_CB(skbp)->ns,
304                                skb_queue_len(&session->reorder_q));
305                         session->stats.rx_oos_packets++;
306                         goto out;
307                 }
308         }
309
310         __skb_queue_tail(&session->reorder_q, skb);
311
312 out:
313         spin_unlock_bh(&session->reorder_q.lock);
314 }
315
316 /* Dequeue a single skb.
317  */
318 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
319 {
320         struct l2tp_tunnel *tunnel = session->tunnel;
321         int length = L2TP_SKB_CB(skb)->length;
322
323         /* We're about to requeue the skb, so return resources
324          * to its current owner (a socket receive buffer).
325          */
326         skb_orphan(skb);
327
328         tunnel->stats.rx_packets++;
329         tunnel->stats.rx_bytes += length;
330         session->stats.rx_packets++;
331         session->stats.rx_bytes += length;
332
333         if (L2TP_SKB_CB(skb)->has_seq) {
334                 /* Bump our Nr */
335                 session->nr++;
336                 if (tunnel->version == L2TP_HDR_VER_2)
337                         session->nr &= 0xffff;
338                 else
339                         session->nr &= 0xffffff;
340
341                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
342                        "%s: updated nr to %hu\n", session->name, session->nr);
343         }
344
345         /* call private receive handler */
346         if (session->recv_skb != NULL)
347                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
348         else
349                 kfree_skb(skb);
350
351         if (session->deref)
352                 (*session->deref)(session);
353 }
354
355 /* Dequeue skbs from the session's reorder_q, subject to packet order.
356  * Skbs that have been in the queue for too long are simply discarded.
357  */
358 static void l2tp_recv_dequeue(struct l2tp_session *session)
359 {
360         struct sk_buff *skb;
361         struct sk_buff *tmp;
362
363         /* If the pkt at the head of the queue has the nr that we
364          * expect to send up next, dequeue it and any other
365          * in-sequence packets behind it.
366          */
367         spin_lock_bh(&session->reorder_q.lock);
368         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
369                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
370                         session->stats.rx_seq_discards++;
371                         session->stats.rx_errors++;
372                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
373                                "%s: oos pkt %u len %d discarded (too old), "
374                                "waiting for %u, reorder_q_len=%d\n",
375                                session->name, L2TP_SKB_CB(skb)->ns,
376                                L2TP_SKB_CB(skb)->length, session->nr,
377                                skb_queue_len(&session->reorder_q));
378                         __skb_unlink(skb, &session->reorder_q);
379                         kfree_skb(skb);
380                         if (session->deref)
381                                 (*session->deref)(session);
382                         continue;
383                 }
384
385                 if (L2TP_SKB_CB(skb)->has_seq) {
386                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
387                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
388                                        "%s: holding oos pkt %u len %d, "
389                                        "waiting for %u, reorder_q_len=%d\n",
390                                        session->name, L2TP_SKB_CB(skb)->ns,
391                                        L2TP_SKB_CB(skb)->length, session->nr,
392                                        skb_queue_len(&session->reorder_q));
393                                 goto out;
394                         }
395                 }
396                 __skb_unlink(skb, &session->reorder_q);
397
398                 /* Process the skb. We release the queue lock while we
399                  * do so to let other contexts process the queue.
400                  */
401                 spin_unlock_bh(&session->reorder_q.lock);
402                 l2tp_recv_dequeue_skb(session, skb);
403                 spin_lock_bh(&session->reorder_q.lock);
404         }
405
406 out:
407         spin_unlock_bh(&session->reorder_q.lock);
408 }
409
410 static inline int l2tp_verify_udp_checksum(struct sock *sk,
411                                            struct sk_buff *skb)
412 {
413         struct udphdr *uh = udp_hdr(skb);
414         u16 ulen = ntohs(uh->len);
415         struct inet_sock *inet;
416         __wsum psum;
417
418         if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
419                 return 0;
420
421         inet = inet_sk(sk);
422         psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
423                                   IPPROTO_UDP, 0);
424
425         if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
426             !csum_fold(csum_add(psum, skb->csum)))
427                 return 0;
428
429         skb->csum = psum;
430
431         return __skb_checksum_complete(skb);
432 }
433
434 /* Do receive processing of L2TP data frames. We handle both L2TPv2
435  * and L2TPv3 data frames here.
436  *
437  * L2TPv2 Data Message Header
438  *
439  *  0                   1                   2                   3
440  *  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
441  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
442  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
443  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
444  * |           Tunnel ID           |           Session ID          |
445  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
446  * |             Ns (opt)          |             Nr (opt)          |
447  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
448  * |      Offset Size (opt)        |    Offset pad... (opt)
449  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
450  *
451  * Data frames are marked by T=0. All other fields are the same as
452  * those in L2TP control frames.
453  *
454  * L2TPv3 Data Message Header
455  *
456  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
457  * |                      L2TP Session Header                      |
458  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
459  * |                      L2-Specific Sublayer                     |
460  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
461  * |                        Tunnel Payload                      ...
462  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
463  *
464  * L2TPv3 Session Header Over IP
465  *
466  *  0                   1                   2                   3
467  *  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
468  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
469  * |                           Session ID                          |
470  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
471  * |               Cookie (optional, maximum 64 bits)...
472  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
473  *                                                                 |
474  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
475  *
476  * L2TPv3 L2-Specific Sublayer Format
477  *
478  *  0                   1                   2                   3
479  *  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
480  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
481  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
482  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
483  *
484  * Cookie value, sublayer format and offset (pad) are negotiated with
485  * the peer when the session is set up. Unlike L2TPv2, we do not need
486  * to parse the packet header to determine if optional fields are
487  * present.
488  *
489  * Caller must already have parsed the frame and determined that it is
490  * a data (not control) frame before coming here. Fields up to the
491  * session-id have already been parsed and ptr points to the data
492  * after the session-id.
493  */
494 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
495                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
496                       int length, int (*payload_hook)(struct sk_buff *skb))
497 {
498         struct l2tp_tunnel *tunnel = session->tunnel;
499         int offset;
500         u32 ns, nr;
501
502         /* The ref count is increased since we now hold a pointer to
503          * the session. Take care to decrement the refcnt when exiting
504          * this function from now on...
505          */
506         l2tp_session_inc_refcount(session);
507         if (session->ref)
508                 (*session->ref)(session);
509
510         /* Parse and check optional cookie */
511         if (session->peer_cookie_len > 0) {
512                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
513                         PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
514                                "%s: cookie mismatch (%u/%u). Discarding.\n",
515                                tunnel->name, tunnel->tunnel_id, session->session_id);
516                         session->stats.rx_cookie_discards++;
517                         goto discard;
518                 }
519                 ptr += session->peer_cookie_len;
520         }
521
522         /* Handle the optional sequence numbers. Sequence numbers are
523          * in different places for L2TPv2 and L2TPv3.
524          *
525          * If we are the LAC, enable/disable sequence numbers under
526          * the control of the LNS.  If no sequence numbers present but
527          * we were expecting them, discard frame.
528          */
529         ns = nr = 0;
530         L2TP_SKB_CB(skb)->has_seq = 0;
531         if (tunnel->version == L2TP_HDR_VER_2) {
532                 if (hdrflags & L2TP_HDRFLAG_S) {
533                         ns = ntohs(*(__be16 *) ptr);
534                         ptr += 2;
535                         nr = ntohs(*(__be16 *) ptr);
536                         ptr += 2;
537
538                         /* Store L2TP info in the skb */
539                         L2TP_SKB_CB(skb)->ns = ns;
540                         L2TP_SKB_CB(skb)->has_seq = 1;
541
542                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
543                                "%s: recv data ns=%u, nr=%u, session nr=%u\n",
544                                session->name, ns, nr, session->nr);
545                 }
546         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
547                 u32 l2h = ntohl(*(__be32 *) ptr);
548
549                 if (l2h & 0x40000000) {
550                         ns = l2h & 0x00ffffff;
551
552                         /* Store L2TP info in the skb */
553                         L2TP_SKB_CB(skb)->ns = ns;
554                         L2TP_SKB_CB(skb)->has_seq = 1;
555
556                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
557                                "%s: recv data ns=%u, session nr=%u\n",
558                                session->name, ns, session->nr);
559                 }
560         }
561
562         /* Advance past L2-specific header, if present */
563         ptr += session->l2specific_len;
564
565         if (L2TP_SKB_CB(skb)->has_seq) {
566                 /* Received a packet with sequence numbers. If we're the LNS,
567                  * check if we sre sending sequence numbers and if not,
568                  * configure it so.
569                  */
570                 if ((!session->lns_mode) && (!session->send_seq)) {
571                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
572                                "%s: requested to enable seq numbers by LNS\n",
573                                session->name);
574                         session->send_seq = -1;
575                         l2tp_session_set_header_len(session, tunnel->version);
576                 }
577         } else {
578                 /* No sequence numbers.
579                  * If user has configured mandatory sequence numbers, discard.
580                  */
581                 if (session->recv_seq) {
582                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
583                                "%s: recv data has no seq numbers when required. "
584                                "Discarding\n", session->name);
585                         session->stats.rx_seq_discards++;
586                         goto discard;
587                 }
588
589                 /* If we're the LAC and we're sending sequence numbers, the
590                  * LNS has requested that we no longer send sequence numbers.
591                  * If we're the LNS and we're sending sequence numbers, the
592                  * LAC is broken. Discard the frame.
593                  */
594                 if ((!session->lns_mode) && (session->send_seq)) {
595                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
596                                "%s: requested to disable seq numbers by LNS\n",
597                                session->name);
598                         session->send_seq = 0;
599                         l2tp_session_set_header_len(session, tunnel->version);
600                 } else if (session->send_seq) {
601                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
602                                "%s: recv data has no seq numbers when required. "
603                                "Discarding\n", session->name);
604                         session->stats.rx_seq_discards++;
605                         goto discard;
606                 }
607         }
608
609         /* Session data offset is handled differently for L2TPv2 and
610          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
611          * the header. For L2TPv3, the offset is negotiated using AVPs
612          * in the session setup control protocol.
613          */
614         if (tunnel->version == L2TP_HDR_VER_2) {
615                 /* If offset bit set, skip it. */
616                 if (hdrflags & L2TP_HDRFLAG_O) {
617                         offset = ntohs(*(__be16 *)ptr);
618                         ptr += 2 + offset;
619                 }
620         } else
621                 ptr += session->offset;
622
623         offset = ptr - optr;
624         if (!pskb_may_pull(skb, offset))
625                 goto discard;
626
627         __skb_pull(skb, offset);
628
629         /* If caller wants to process the payload before we queue the
630          * packet, do so now.
631          */
632         if (payload_hook)
633                 if ((*payload_hook)(skb))
634                         goto discard;
635
636         /* Prepare skb for adding to the session's reorder_q.  Hold
637          * packets for max reorder_timeout or 1 second if not
638          * reordering.
639          */
640         L2TP_SKB_CB(skb)->length = length;
641         L2TP_SKB_CB(skb)->expires = jiffies +
642                 (session->reorder_timeout ? session->reorder_timeout : HZ);
643
644         /* Add packet to the session's receive queue. Reordering is done here, if
645          * enabled. Saved L2TP protocol info is stored in skb->sb[].
646          */
647         if (L2TP_SKB_CB(skb)->has_seq) {
648                 if (session->reorder_timeout != 0) {
649                         /* Packet reordering enabled. Add skb to session's
650                          * reorder queue, in order of ns.
651                          */
652                         l2tp_recv_queue_skb(session, skb);
653                 } else {
654                         /* Packet reordering disabled. Discard out-of-sequence
655                          * packets
656                          */
657                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
658                                 session->stats.rx_seq_discards++;
659                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
660                                        "%s: oos pkt %u len %d discarded, "
661                                        "waiting for %u, reorder_q_len=%d\n",
662                                        session->name, L2TP_SKB_CB(skb)->ns,
663                                        L2TP_SKB_CB(skb)->length, session->nr,
664                                        skb_queue_len(&session->reorder_q));
665                                 goto discard;
666                         }
667                         skb_queue_tail(&session->reorder_q, skb);
668                 }
669         } else {
670                 /* No sequence numbers. Add the skb to the tail of the
671                  * reorder queue. This ensures that it will be
672                  * delivered after all previous sequenced skbs.
673                  */
674                 skb_queue_tail(&session->reorder_q, skb);
675         }
676
677         /* Try to dequeue as many skbs from reorder_q as we can. */
678         l2tp_recv_dequeue(session);
679
680         l2tp_session_dec_refcount(session);
681
682         return;
683
684 discard:
685         session->stats.rx_errors++;
686         kfree_skb(skb);
687
688         if (session->deref)
689                 (*session->deref)(session);
690
691         l2tp_session_dec_refcount(session);
692 }
693 EXPORT_SYMBOL(l2tp_recv_common);
694
695 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
696  * here. The skb is not on a list when we get here.
697  * Returns 0 if the packet was a data packet and was successfully passed on.
698  * Returns 1 if the packet was not a good data packet and could not be
699  * forwarded.  All such packets are passed up to userspace to deal with.
700  */
701 int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
702                        int (*payload_hook)(struct sk_buff *skb))
703 {
704         struct l2tp_session *session = NULL;
705         unsigned char *ptr, *optr;
706         u16 hdrflags;
707         u32 tunnel_id, session_id;
708         int offset;
709         u16 version;
710         int length;
711
712         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
713                 goto discard_bad_csum;
714
715         /* UDP always verifies the packet length. */
716         __skb_pull(skb, sizeof(struct udphdr));
717
718         /* Short packet? */
719         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
720                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
721                        "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
722                 goto error;
723         }
724
725         /* Point to L2TP header */
726         optr = ptr = skb->data;
727
728         /* Trace packet contents, if enabled */
729         if (tunnel->debug & L2TP_MSG_DATA) {
730                 length = min(32u, skb->len);
731                 if (!pskb_may_pull(skb, length))
732                         goto error;
733
734                 printk(KERN_DEBUG "%s: recv: ", tunnel->name);
735
736                 offset = 0;
737                 do {
738                         printk(" %02X", ptr[offset]);
739                 } while (++offset < length);
740
741                 printk("\n");
742         }
743
744         /* Get L2TP header flags */
745         hdrflags = ntohs(*(__be16 *) ptr);
746
747         /* Check protocol version */
748         version = hdrflags & L2TP_HDR_VER_MASK;
749         if (version != tunnel->version) {
750                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
751                        "%s: recv protocol version mismatch: got %d expected %d\n",
752                        tunnel->name, version, tunnel->version);
753                 goto error;
754         }
755
756         /* Get length of L2TP packet */
757         length = skb->len;
758
759         /* If type is control packet, it is handled by userspace. */
760         if (hdrflags & L2TP_HDRFLAG_T) {
761                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
762                        "%s: recv control packet, len=%d\n", tunnel->name, length);
763                 goto error;
764         }
765
766         /* Skip flags */
767         ptr += 2;
768
769         if (tunnel->version == L2TP_HDR_VER_2) {
770                 /* If length is present, skip it */
771                 if (hdrflags & L2TP_HDRFLAG_L)
772                         ptr += 2;
773
774                 /* Extract tunnel and session ID */
775                 tunnel_id = ntohs(*(__be16 *) ptr);
776                 ptr += 2;
777                 session_id = ntohs(*(__be16 *) ptr);
778                 ptr += 2;
779         } else {
780                 ptr += 2;       /* skip reserved bits */
781                 tunnel_id = tunnel->tunnel_id;
782                 session_id = ntohl(*(__be32 *) ptr);
783                 ptr += 4;
784         }
785
786         /* Find the session context */
787         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
788         if (!session || !session->recv_skb) {
789                 /* Not found? Pass to userspace to deal with */
790                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
791                        "%s: no session found (%u/%u). Passing up.\n",
792                        tunnel->name, tunnel_id, session_id);
793                 goto error;
794         }
795
796         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
797
798         return 0;
799
800 discard_bad_csum:
801         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
802         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
803         tunnel->stats.rx_errors++;
804         kfree_skb(skb);
805
806         return 0;
807
808 error:
809         /* Put UDP header back */
810         __skb_push(skb, sizeof(struct udphdr));
811
812         return 1;
813 }
814 EXPORT_SYMBOL_GPL(l2tp_udp_recv_core);
815
816 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
817  * Return codes:
818  * 0 : success.
819  * <0: error
820  * >0: skb should be passed up to userspace as UDP.
821  */
822 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
823 {
824         struct l2tp_tunnel *tunnel;
825
826         tunnel = l2tp_sock_to_tunnel(sk);
827         if (tunnel == NULL)
828                 goto pass_up;
829
830         PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
831                "%s: received %d bytes\n", tunnel->name, skb->len);
832
833         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
834                 goto pass_up_put;
835
836         sock_put(sk);
837         return 0;
838
839 pass_up_put:
840         sock_put(sk);
841 pass_up:
842         return 1;
843 }
844 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
845
846 /************************************************************************
847  * Transmit handling
848  ***********************************************************************/
849
850 /* Build an L2TP header for the session into the buffer provided.
851  */
852 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
853 {
854         struct l2tp_tunnel *tunnel = session->tunnel;
855         __be16 *bufp = buf;
856         __be16 *optr = buf;
857         u16 flags = L2TP_HDR_VER_2;
858         u32 tunnel_id = tunnel->peer_tunnel_id;
859         u32 session_id = session->peer_session_id;
860
861         if (session->send_seq)
862                 flags |= L2TP_HDRFLAG_S;
863
864         /* Setup L2TP header. */
865         *bufp++ = htons(flags);
866         *bufp++ = htons(tunnel_id);
867         *bufp++ = htons(session_id);
868         if (session->send_seq) {
869                 *bufp++ = htons(session->ns);
870                 *bufp++ = 0;
871                 session->ns++;
872                 session->ns &= 0xffff;
873                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
874                        "%s: updated ns to %u\n", session->name, session->ns);
875         }
876
877         return bufp - optr;
878 }
879
880 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
881 {
882         struct l2tp_tunnel *tunnel = session->tunnel;
883         char *bufp = buf;
884         char *optr = bufp;
885
886         /* Setup L2TP header. The header differs slightly for UDP and
887          * IP encapsulations. For UDP, there is 4 bytes of flags.
888          */
889         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
890                 u16 flags = L2TP_HDR_VER_3;
891                 *((__be16 *) bufp) = htons(flags);
892                 bufp += 2;
893                 *((__be16 *) bufp) = 0;
894                 bufp += 2;
895         }
896
897         *((__be32 *) bufp) = htonl(session->peer_session_id);
898         bufp += 4;
899         if (session->cookie_len) {
900                 memcpy(bufp, &session->cookie[0], session->cookie_len);
901                 bufp += session->cookie_len;
902         }
903         if (session->l2specific_len) {
904                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
905                         u32 l2h = 0;
906                         if (session->send_seq) {
907                                 l2h = 0x40000000 | session->ns;
908                                 session->ns++;
909                                 session->ns &= 0xffffff;
910                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
911                                        "%s: updated ns to %u\n", session->name, session->ns);
912                         }
913
914                         *((__be32 *) bufp) = htonl(l2h);
915                 }
916                 bufp += session->l2specific_len;
917         }
918         if (session->offset)
919                 bufp += session->offset;
920
921         return bufp - optr;
922 }
923
924 int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len)
925 {
926         struct l2tp_tunnel *tunnel = session->tunnel;
927         unsigned int len = skb->len;
928         int error;
929
930         /* Debug */
931         if (session->send_seq)
932                 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
933                        "%s: send %Zd bytes, ns=%u\n", session->name,
934                        data_len, session->ns - 1);
935         else
936                 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
937                        "%s: send %Zd bytes\n", session->name, data_len);
938
939         if (session->debug & L2TP_MSG_DATA) {
940                 int i;
941                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
942                 unsigned char *datap = skb->data + uhlen;
943
944                 printk(KERN_DEBUG "%s: xmit:", session->name);
945                 for (i = 0; i < (len - uhlen); i++) {
946                         printk(" %02X", *datap++);
947                         if (i == 31) {
948                                 printk(" ...");
949                                 break;
950                         }
951                 }
952                 printk("\n");
953         }
954
955         /* Queue the packet to IP for output */
956         error = ip_queue_xmit(skb, 1);
957
958         /* Update stats */
959         if (error >= 0) {
960                 tunnel->stats.tx_packets++;
961                 tunnel->stats.tx_bytes += len;
962                 session->stats.tx_packets++;
963                 session->stats.tx_bytes += len;
964         } else {
965                 tunnel->stats.tx_errors++;
966                 session->stats.tx_errors++;
967         }
968
969         return 0;
970 }
971 EXPORT_SYMBOL_GPL(l2tp_xmit_core);
972
973 /* Automatically called when the skb is freed.
974  */
975 static void l2tp_sock_wfree(struct sk_buff *skb)
976 {
977         sock_put(skb->sk);
978 }
979
980 /* For data skbs that we transmit, we associate with the tunnel socket
981  * but don't do accounting.
982  */
983 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
984 {
985         sock_hold(sk);
986         skb->sk = sk;
987         skb->destructor = l2tp_sock_wfree;
988 }
989
990 /* If caller requires the skb to have a ppp header, the header must be
991  * inserted in the skb data before calling this function.
992  */
993 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
994 {
995         int data_len = skb->len;
996         struct l2tp_tunnel *tunnel = session->tunnel;
997         struct sock *sk = tunnel->sock;
998         struct udphdr *uh;
999         struct inet_sock *inet;
1000         __wsum csum;
1001         int old_headroom;
1002         int new_headroom;
1003         int headroom;
1004         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1005         int udp_len;
1006
1007         /* Check that there's enough headroom in the skb to insert IP,
1008          * UDP and L2TP headers. If not enough, expand it to
1009          * make room. Adjust truesize.
1010          */
1011         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1012                 uhlen + hdr_len;
1013         old_headroom = skb_headroom(skb);
1014         if (skb_cow_head(skb, headroom))
1015                 goto abort;
1016
1017         new_headroom = skb_headroom(skb);
1018         skb_orphan(skb);
1019         skb->truesize += new_headroom - old_headroom;
1020
1021         /* Setup L2TP header */
1022         session->build_header(session, __skb_push(skb, hdr_len));
1023
1024         /* Reset skb netfilter state */
1025         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1026         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1027                               IPSKB_REROUTED);
1028         nf_reset(skb);
1029
1030         /* Get routing info from the tunnel socket */
1031         skb_dst_drop(skb);
1032         skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
1033
1034         switch (tunnel->encap) {
1035         case L2TP_ENCAPTYPE_UDP:
1036                 /* Setup UDP header */
1037                 inet = inet_sk(sk);
1038                 __skb_push(skb, sizeof(*uh));
1039                 skb_reset_transport_header(skb);
1040                 uh = udp_hdr(skb);
1041                 uh->source = inet->inet_sport;
1042                 uh->dest = inet->inet_dport;
1043                 udp_len = uhlen + hdr_len + data_len;
1044                 uh->len = htons(udp_len);
1045                 uh->check = 0;
1046
1047                 /* Calculate UDP checksum if configured to do so */
1048                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1049                         skb->ip_summed = CHECKSUM_NONE;
1050                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1051                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1052                         skb->ip_summed = CHECKSUM_COMPLETE;
1053                         csum = skb_checksum(skb, 0, udp_len, 0);
1054                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1055                                                       inet->inet_daddr,
1056                                                       udp_len, IPPROTO_UDP, csum);
1057                         if (uh->check == 0)
1058                                 uh->check = CSUM_MANGLED_0;
1059                 } else {
1060                         skb->ip_summed = CHECKSUM_PARTIAL;
1061                         skb->csum_start = skb_transport_header(skb) - skb->head;
1062                         skb->csum_offset = offsetof(struct udphdr, check);
1063                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1064                                                        inet->inet_daddr,
1065                                                        udp_len, IPPROTO_UDP, 0);
1066                 }
1067                 break;
1068
1069         case L2TP_ENCAPTYPE_IP:
1070                 break;
1071         }
1072
1073         l2tp_skb_set_owner_w(skb, sk);
1074
1075         l2tp_xmit_core(session, skb, data_len);
1076
1077 abort:
1078         return 0;
1079 }
1080 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1081
1082 /*****************************************************************************
1083  * Tinnel and session create/destroy.
1084  *****************************************************************************/
1085
1086 /* Tunnel socket destruct hook.
1087  * The tunnel context is deleted only when all session sockets have been
1088  * closed.
1089  */
1090 void l2tp_tunnel_destruct(struct sock *sk)
1091 {
1092         struct l2tp_tunnel *tunnel;
1093
1094         tunnel = sk->sk_user_data;
1095         if (tunnel == NULL)
1096                 goto end;
1097
1098         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1099                "%s: closing...\n", tunnel->name);
1100
1101         /* Close all sessions */
1102         l2tp_tunnel_closeall(tunnel);
1103
1104         switch (tunnel->encap) {
1105         case L2TP_ENCAPTYPE_UDP:
1106                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1107                 (udp_sk(sk))->encap_type = 0;
1108                 (udp_sk(sk))->encap_rcv = NULL;
1109                 break;
1110         case L2TP_ENCAPTYPE_IP:
1111                 break;
1112         }
1113
1114         /* Remove hooks into tunnel socket */
1115         tunnel->sock = NULL;
1116         sk->sk_destruct = tunnel->old_sk_destruct;
1117         sk->sk_user_data = NULL;
1118
1119         /* Call the original destructor */
1120         if (sk->sk_destruct)
1121                 (*sk->sk_destruct)(sk);
1122
1123         /* We're finished with the socket */
1124         l2tp_tunnel_dec_refcount(tunnel);
1125
1126 end:
1127         return;
1128 }
1129 EXPORT_SYMBOL(l2tp_tunnel_destruct);
1130
1131 /* When the tunnel is closed, all the attached sessions need to go too.
1132  */
1133 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1134 {
1135         int hash;
1136         struct hlist_node *walk;
1137         struct hlist_node *tmp;
1138         struct l2tp_session *session;
1139
1140         BUG_ON(tunnel == NULL);
1141
1142         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1143                "%s: closing all sessions...\n", tunnel->name);
1144
1145         write_lock_bh(&tunnel->hlist_lock);
1146         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1147 again:
1148                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1149                         session = hlist_entry(walk, struct l2tp_session, hlist);
1150
1151                         PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
1152                                "%s: closing session\n", session->name);
1153
1154                         hlist_del_init(&session->hlist);
1155
1156                         /* Since we should hold the sock lock while
1157                          * doing any unbinding, we need to release the
1158                          * lock we're holding before taking that lock.
1159                          * Hold a reference to the sock so it doesn't
1160                          * disappear as we're jumping between locks.
1161                          */
1162                         if (session->ref != NULL)
1163                                 (*session->ref)(session);
1164
1165                         write_unlock_bh(&tunnel->hlist_lock);
1166
1167                         if (tunnel->version != L2TP_HDR_VER_2) {
1168                                 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1169
1170                                 write_lock_bh(&pn->l2tp_session_hlist_lock);
1171                                 hlist_del_init(&session->global_hlist);
1172                                 write_unlock_bh(&pn->l2tp_session_hlist_lock);
1173                         }
1174
1175                         if (session->session_close != NULL)
1176                                 (*session->session_close)(session);
1177
1178                         if (session->deref != NULL)
1179                                 (*session->deref)(session);
1180
1181                         write_lock_bh(&tunnel->hlist_lock);
1182
1183                         /* Now restart from the beginning of this hash
1184                          * chain.  We always remove a session from the
1185                          * list so we are guaranteed to make forward
1186                          * progress.
1187                          */
1188                         goto again;
1189                 }
1190         }
1191         write_unlock_bh(&tunnel->hlist_lock);
1192 }
1193 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1194
1195 /* Really kill the tunnel.
1196  * Come here only when all sessions have been cleared from the tunnel.
1197  */
1198 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1199 {
1200         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1201
1202         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1203         BUG_ON(tunnel->sock != NULL);
1204
1205         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1206                "%s: free...\n", tunnel->name);
1207
1208         /* Remove from tunnel list */
1209         write_lock_bh(&pn->l2tp_tunnel_list_lock);
1210         list_del_init(&tunnel->list);
1211         write_unlock_bh(&pn->l2tp_tunnel_list_lock);
1212
1213         atomic_dec(&l2tp_tunnel_count);
1214         kfree(tunnel);
1215 }
1216 EXPORT_SYMBOL_GPL(l2tp_tunnel_free);
1217
1218 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)
1219 {
1220         struct l2tp_tunnel *tunnel = NULL;
1221         int err;
1222         struct socket *sock = NULL;
1223         struct sock *sk = NULL;
1224         struct l2tp_net *pn;
1225         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1226
1227         /* Get the tunnel socket from the fd, which was opened by
1228          * the userspace L2TP daemon.
1229          */
1230         err = -EBADF;
1231         sock = sockfd_lookup(fd, &err);
1232         if (!sock) {
1233                 printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1234                        tunnel_id, fd, err);
1235                 goto err;
1236         }
1237
1238         sk = sock->sk;
1239
1240         if (cfg != NULL)
1241                 encap = cfg->encap;
1242
1243         /* Quick sanity checks */
1244         switch (encap) {
1245         case L2TP_ENCAPTYPE_UDP:
1246                 err = -EPROTONOSUPPORT;
1247                 if (sk->sk_protocol != IPPROTO_UDP) {
1248                         printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1249                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1250                         goto err;
1251                 }
1252                 break;
1253         case L2TP_ENCAPTYPE_IP:
1254                 err = -EPROTONOSUPPORT;
1255                 if (sk->sk_protocol != IPPROTO_L2TP) {
1256                         printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1257                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1258                         goto err;
1259                 }
1260                 break;
1261         }
1262
1263         /* Check if this socket has already been prepped */
1264         tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1265         if (tunnel != NULL) {
1266                 /* This socket has already been prepped */
1267                 err = -EBUSY;
1268                 goto err;
1269         }
1270
1271         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1272         if (tunnel == NULL) {
1273                 err = -ENOMEM;
1274                 goto err;
1275         }
1276
1277         tunnel->version = version;
1278         tunnel->tunnel_id = tunnel_id;
1279         tunnel->peer_tunnel_id = peer_tunnel_id;
1280         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1281
1282         tunnel->magic = L2TP_TUNNEL_MAGIC;
1283         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1284         rwlock_init(&tunnel->hlist_lock);
1285
1286         /* The net we belong to */
1287         tunnel->l2tp_net = net;
1288         pn = l2tp_pernet(net);
1289
1290         if (cfg != NULL)
1291                 tunnel->debug = cfg->debug;
1292
1293         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1294         tunnel->encap = encap;
1295         if (encap == L2TP_ENCAPTYPE_UDP) {
1296                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1297                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1298                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1299         }
1300
1301         sk->sk_user_data = tunnel;
1302
1303         /* Hook on the tunnel socket destructor so that we can cleanup
1304          * if the tunnel socket goes away.
1305          */
1306         tunnel->old_sk_destruct = sk->sk_destruct;
1307         sk->sk_destruct = &l2tp_tunnel_destruct;
1308         tunnel->sock = sk;
1309         sk->sk_allocation = GFP_ATOMIC;
1310
1311         /* Add tunnel to our list */
1312         INIT_LIST_HEAD(&tunnel->list);
1313         write_lock_bh(&pn->l2tp_tunnel_list_lock);
1314         list_add(&tunnel->list, &pn->l2tp_tunnel_list);
1315         write_unlock_bh(&pn->l2tp_tunnel_list_lock);
1316         atomic_inc(&l2tp_tunnel_count);
1317
1318         /* Bump the reference count. The tunnel context is deleted
1319          * only when this drops to zero.
1320          */
1321         l2tp_tunnel_inc_refcount(tunnel);
1322
1323         err = 0;
1324 err:
1325         if (tunnelp)
1326                 *tunnelp = tunnel;
1327
1328         if (sock)
1329                 sockfd_put(sock);
1330
1331         return err;
1332 }
1333 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1334
1335 /* This function is used by the netlink TUNNEL_DELETE command.
1336  */
1337 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1338 {
1339         int err = 0;
1340
1341         /* Force the tunnel socket to close. This will eventually
1342          * cause the tunnel to be deleted via the normal socket close
1343          * mechanisms when userspace closes the tunnel socket.
1344          */
1345         if ((tunnel->sock != NULL) && (tunnel->sock->sk_socket != NULL))
1346                 err = inet_shutdown(tunnel->sock->sk_socket, 2);
1347
1348         return err;
1349 }
1350 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1351
1352 /* Really kill the session.
1353  */
1354 void l2tp_session_free(struct l2tp_session *session)
1355 {
1356         struct l2tp_tunnel *tunnel;
1357
1358         BUG_ON(atomic_read(&session->ref_count) != 0);
1359
1360         tunnel = session->tunnel;
1361         if (tunnel != NULL) {
1362                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1363
1364                 /* Delete the session from the hash */
1365                 write_lock_bh(&tunnel->hlist_lock);
1366                 hlist_del_init(&session->hlist);
1367                 write_unlock_bh(&tunnel->hlist_lock);
1368
1369                 /* Unlink from the global hash if not L2TPv2 */
1370                 if (tunnel->version != L2TP_HDR_VER_2) {
1371                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1372
1373                         write_lock_bh(&pn->l2tp_session_hlist_lock);
1374                         hlist_del_init(&session->global_hlist);
1375                         write_unlock_bh(&pn->l2tp_session_hlist_lock);
1376                 }
1377
1378                 if (session->session_id != 0)
1379                         atomic_dec(&l2tp_session_count);
1380
1381                 sock_put(tunnel->sock);
1382
1383                 /* This will delete the tunnel context if this
1384                  * is the last session on the tunnel.
1385                  */
1386                 session->tunnel = NULL;
1387                 l2tp_tunnel_dec_refcount(tunnel);
1388         }
1389
1390         kfree(session);
1391
1392         return;
1393 }
1394 EXPORT_SYMBOL_GPL(l2tp_session_free);
1395
1396 /* This function is used by the netlink SESSION_DELETE command and by
1397    pseudowire modules.
1398  */
1399 int l2tp_session_delete(struct l2tp_session *session)
1400 {
1401         if (session->session_close != NULL)
1402                 (*session->session_close)(session);
1403
1404         l2tp_session_dec_refcount(session);
1405
1406         return 0;
1407 }
1408 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1409
1410
1411 /* We come here whenever a session's send_seq, cookie_len or
1412  * l2specific_len parameters are set.
1413  */
1414 void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1415 {
1416         if (version == L2TP_HDR_VER_2) {
1417                 session->hdr_len = 6;
1418                 if (session->send_seq)
1419                         session->hdr_len += 4;
1420         } else {
1421                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1422                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1423                         session->hdr_len += 4;
1424         }
1425
1426 }
1427 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1428
1429 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)
1430 {
1431         struct l2tp_session *session;
1432
1433         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1434         if (session != NULL) {
1435                 session->magic = L2TP_SESSION_MAGIC;
1436                 session->tunnel = tunnel;
1437
1438                 session->session_id = session_id;
1439                 session->peer_session_id = peer_session_id;
1440                 session->nr = 1;
1441
1442                 sprintf(&session->name[0], "sess %u/%u",
1443                         tunnel->tunnel_id, session->session_id);
1444
1445                 skb_queue_head_init(&session->reorder_q);
1446
1447                 INIT_HLIST_NODE(&session->hlist);
1448                 INIT_HLIST_NODE(&session->global_hlist);
1449
1450                 /* Inherit debug options from tunnel */
1451                 session->debug = tunnel->debug;
1452
1453                 if (cfg) {
1454                         session->pwtype = cfg->pw_type;
1455                         session->debug = cfg->debug;
1456                         session->mtu = cfg->mtu;
1457                         session->mru = cfg->mru;
1458                         session->send_seq = cfg->send_seq;
1459                         session->recv_seq = cfg->recv_seq;
1460                         session->lns_mode = cfg->lns_mode;
1461                         session->reorder_timeout = cfg->reorder_timeout;
1462                         session->offset = cfg->offset;
1463                         session->l2specific_type = cfg->l2specific_type;
1464                         session->l2specific_len = cfg->l2specific_len;
1465                         session->cookie_len = cfg->cookie_len;
1466                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1467                         session->peer_cookie_len = cfg->peer_cookie_len;
1468                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1469                 }
1470
1471                 if (tunnel->version == L2TP_HDR_VER_2)
1472                         session->build_header = l2tp_build_l2tpv2_header;
1473                 else
1474                         session->build_header = l2tp_build_l2tpv3_header;
1475
1476                 l2tp_session_set_header_len(session, tunnel->version);
1477
1478                 /* Bump the reference count. The session context is deleted
1479                  * only when this drops to zero.
1480                  */
1481                 l2tp_session_inc_refcount(session);
1482                 l2tp_tunnel_inc_refcount(tunnel);
1483
1484                 /* Ensure tunnel socket isn't deleted */
1485                 sock_hold(tunnel->sock);
1486
1487                 /* Add session to the tunnel's hash list */
1488                 write_lock_bh(&tunnel->hlist_lock);
1489                 hlist_add_head(&session->hlist,
1490                                l2tp_session_id_hash(tunnel, session_id));
1491                 write_unlock_bh(&tunnel->hlist_lock);
1492
1493                 /* And to the global session list if L2TPv3 */
1494                 if (tunnel->version != L2TP_HDR_VER_2) {
1495                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1496
1497                         write_lock_bh(&pn->l2tp_session_hlist_lock);
1498                         hlist_add_head(&session->global_hlist,
1499                                        l2tp_session_id_hash_2(pn, session_id));
1500                         write_unlock_bh(&pn->l2tp_session_hlist_lock);
1501                 }
1502
1503                 /* Ignore management session in session count value */
1504                 if (session->session_id != 0)
1505                         atomic_inc(&l2tp_session_count);
1506         }
1507
1508         return session;
1509 }
1510 EXPORT_SYMBOL_GPL(l2tp_session_create);
1511
1512 /*****************************************************************************
1513  * Init and cleanup
1514  *****************************************************************************/
1515
1516 static __net_init int l2tp_init_net(struct net *net)
1517 {
1518         struct l2tp_net *pn;
1519         int err;
1520         int hash;
1521
1522         pn = kzalloc(sizeof(*pn), GFP_KERNEL);
1523         if (!pn)
1524                 return -ENOMEM;
1525
1526         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1527         rwlock_init(&pn->l2tp_tunnel_list_lock);
1528
1529         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1530                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1531
1532         rwlock_init(&pn->l2tp_session_hlist_lock);
1533
1534         err = net_assign_generic(net, l2tp_net_id, pn);
1535         if (err)
1536                 goto out;
1537
1538         return 0;
1539
1540 out:
1541         kfree(pn);
1542         return err;
1543 }
1544
1545 static __net_exit void l2tp_exit_net(struct net *net)
1546 {
1547         struct l2tp_net *pn;
1548
1549         pn = net_generic(net, l2tp_net_id);
1550         /*
1551          * if someone has cached our net then
1552          * further net_generic call will return NULL
1553          */
1554         net_assign_generic(net, l2tp_net_id, NULL);
1555         kfree(pn);
1556 }
1557
1558 static struct pernet_operations l2tp_net_ops = {
1559         .init = l2tp_init_net,
1560         .exit = l2tp_exit_net,
1561         .id   = &l2tp_net_id,
1562         .size = sizeof(struct l2tp_net),
1563 };
1564
1565 static int __init l2tp_init(void)
1566 {
1567         int rc = 0;
1568
1569         rc = register_pernet_device(&l2tp_net_ops);
1570         if (rc)
1571                 goto out;
1572
1573         printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);
1574
1575 out:
1576         return rc;
1577 }
1578
1579 static void __exit l2tp_exit(void)
1580 {
1581         unregister_pernet_device(&l2tp_net_ops);
1582 }
1583
1584 module_init(l2tp_init);
1585 module_exit(l2tp_exit);
1586
1587 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1588 MODULE_DESCRIPTION("L2TP core");
1589 MODULE_LICENSE("GPL");
1590 MODULE_VERSION(L2TP_DRV_VERSION);
1591