4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
6 * This file contains some code of the original L2TPv2 pppol2tp
7 * driver, which has the following copyright:
9 * Authors: Martijn van Oosterhout <kleptog@svana.org>
10 * James Chapman (jchapman@katalix.com)
12 * Michal Ostrowski <mostrows@speakeasy.net>
13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
14 * David S. Miller (davem@redhat.com)
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.
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
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>
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>
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>
55 #include <net/inet_common.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>
63 #include <asm/byteorder.h>
64 #include <linux/atomic.h>
66 #include "l2tp_core.h"
68 #define L2TP_DRV_VERSION "V2.0"
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
77 #define L2TP_HDR_VER_MASK 0x000F
78 #define L2TP_HDR_VER_2 0x0002
79 #define L2TP_HDR_VER_3 0x0003
81 /* L2TPv3 default L2-specific sublayer */
82 #define L2TP_SLFLAG_S 0x40000000
83 #define L2TP_SL_SEQ_MASK 0x00ffffff
85 #define L2TP_HDR_SIZE_SEQ 10
86 #define L2TP_HDR_SIZE_NOSEQ 6
88 /* Default trace flags */
89 #define L2TP_DEFAULT_DEBUG_FLAGS 0
91 /* Private data stored for received packets in the skb.
97 unsigned long expires;
100 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
102 static atomic_t l2tp_tunnel_count;
103 static atomic_t l2tp_session_count;
104 static struct workqueue_struct *l2tp_wq;
106 /* per-net private data for this module */
107 static unsigned int l2tp_net_id;
109 struct list_head l2tp_tunnel_list;
110 spinlock_t l2tp_tunnel_list_lock;
111 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
112 spinlock_t l2tp_session_hlist_lock;
115 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
116 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
117 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
119 static inline struct l2tp_net *l2tp_pernet(struct net *net)
123 return net_generic(net, l2tp_net_id);
126 /* Tunnel reference counts. Incremented per session that is added to
129 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
131 atomic_inc(&tunnel->ref_count);
134 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
136 if (atomic_dec_and_test(&tunnel->ref_count))
137 l2tp_tunnel_free(tunnel);
139 #ifdef L2TP_REFCNT_DEBUG
140 #define l2tp_tunnel_inc_refcount(_t) \
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); \
147 #define l2tp_tunnel_dec_refcount(_t)
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); \
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)
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.
164 static inline struct hlist_head *
165 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
167 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
171 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
172 * owned by userspace. A struct sock returned from this function must be
173 * released using l2tp_tunnel_sock_put once you're done with it.
175 struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
178 struct socket *sock = NULL;
179 struct sock *sk = NULL;
184 if (tunnel->fd >= 0) {
185 /* Socket is owned by userspace, who might be in the process
186 * of closing it. Look the socket up using the fd to ensure
189 sock = sockfd_lookup(tunnel->fd, &err);
193 /* Socket is owned by kernelspace */
200 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_lookup);
202 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
203 void l2tp_tunnel_sock_put(struct sock *sk)
205 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
207 if (tunnel->fd >= 0) {
208 /* Socket is owned by userspace */
209 sockfd_put(sk->sk_socket);
214 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_put);
216 /* Lookup a session by id in the global session list
218 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
220 struct l2tp_net *pn = l2tp_pernet(net);
221 struct hlist_head *session_list =
222 l2tp_session_id_hash_2(pn, session_id);
223 struct l2tp_session *session;
226 hlist_for_each_entry_rcu(session, session_list, global_hlist) {
227 if (session->session_id == session_id) {
228 rcu_read_unlock_bh();
232 rcu_read_unlock_bh();
237 /* Session hash list.
238 * The session_id SHOULD be random according to RFC2661, but several
239 * L2TP implementations (Cisco and Microsoft) use incrementing
240 * session_ids. So we do a real hash on the session_id, rather than a
243 static inline struct hlist_head *
244 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
246 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
249 /* Lookup a session by id
251 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
253 struct hlist_head *session_list;
254 struct l2tp_session *session;
256 /* In L2TPv3, session_ids are unique over all tunnels and we
257 * sometimes need to look them up before we know the
261 return l2tp_session_find_2(net, session_id);
263 session_list = l2tp_session_id_hash(tunnel, session_id);
264 read_lock_bh(&tunnel->hlist_lock);
265 hlist_for_each_entry(session, session_list, hlist) {
266 if (session->session_id == session_id) {
267 read_unlock_bh(&tunnel->hlist_lock);
271 read_unlock_bh(&tunnel->hlist_lock);
275 EXPORT_SYMBOL_GPL(l2tp_session_find);
277 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
280 struct l2tp_session *session;
283 read_lock_bh(&tunnel->hlist_lock);
284 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
285 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
287 read_unlock_bh(&tunnel->hlist_lock);
293 read_unlock_bh(&tunnel->hlist_lock);
297 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
299 /* Lookup a session by interface name.
300 * This is very inefficient but is only used by management interfaces.
302 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
304 struct l2tp_net *pn = l2tp_pernet(net);
306 struct l2tp_session *session;
309 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
310 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
311 if (!strcmp(session->ifname, ifname)) {
312 rcu_read_unlock_bh();
318 rcu_read_unlock_bh();
322 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
324 /* Lookup a tunnel by id
326 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
328 struct l2tp_tunnel *tunnel;
329 struct l2tp_net *pn = l2tp_pernet(net);
332 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
333 if (tunnel->tunnel_id == tunnel_id) {
334 rcu_read_unlock_bh();
338 rcu_read_unlock_bh();
342 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
344 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
346 struct l2tp_net *pn = l2tp_pernet(net);
347 struct l2tp_tunnel *tunnel;
351 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
353 rcu_read_unlock_bh();
358 rcu_read_unlock_bh();
362 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
364 /*****************************************************************************
365 * Receive data handling
366 *****************************************************************************/
368 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
371 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
373 struct sk_buff *skbp;
375 u32 ns = L2TP_SKB_CB(skb)->ns;
376 struct l2tp_stats *sstats;
378 spin_lock_bh(&session->reorder_q.lock);
379 sstats = &session->stats;
380 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
381 if (L2TP_SKB_CB(skbp)->ns > ns) {
382 __skb_queue_before(&session->reorder_q, skbp, skb);
383 l2tp_dbg(session, L2TP_MSG_SEQ,
384 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
385 session->name, ns, L2TP_SKB_CB(skbp)->ns,
386 skb_queue_len(&session->reorder_q));
387 u64_stats_update_begin(&sstats->syncp);
388 sstats->rx_oos_packets++;
389 u64_stats_update_end(&sstats->syncp);
394 __skb_queue_tail(&session->reorder_q, skb);
397 spin_unlock_bh(&session->reorder_q.lock);
400 /* Dequeue a single skb.
402 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
404 struct l2tp_tunnel *tunnel = session->tunnel;
405 int length = L2TP_SKB_CB(skb)->length;
406 struct l2tp_stats *tstats, *sstats;
408 /* We're about to requeue the skb, so return resources
409 * to its current owner (a socket receive buffer).
413 tstats = &tunnel->stats;
414 u64_stats_update_begin(&tstats->syncp);
415 sstats = &session->stats;
416 u64_stats_update_begin(&sstats->syncp);
417 tstats->rx_packets++;
418 tstats->rx_bytes += length;
419 sstats->rx_packets++;
420 sstats->rx_bytes += length;
421 u64_stats_update_end(&tstats->syncp);
422 u64_stats_update_end(&sstats->syncp);
424 if (L2TP_SKB_CB(skb)->has_seq) {
427 if (tunnel->version == L2TP_HDR_VER_2)
428 session->nr &= 0xffff;
430 session->nr &= 0xffffff;
432 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
433 session->name, session->nr);
436 /* call private receive handler */
437 if (session->recv_skb != NULL)
438 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
443 (*session->deref)(session);
446 /* Dequeue skbs from the session's reorder_q, subject to packet order.
447 * Skbs that have been in the queue for too long are simply discarded.
449 static void l2tp_recv_dequeue(struct l2tp_session *session)
453 struct l2tp_stats *sstats;
455 /* If the pkt at the head of the queue has the nr that we
456 * expect to send up next, dequeue it and any other
457 * in-sequence packets behind it.
460 spin_lock_bh(&session->reorder_q.lock);
461 sstats = &session->stats;
462 skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
463 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
464 u64_stats_update_begin(&sstats->syncp);
465 sstats->rx_seq_discards++;
467 u64_stats_update_end(&sstats->syncp);
468 l2tp_dbg(session, L2TP_MSG_SEQ,
469 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
470 session->name, L2TP_SKB_CB(skb)->ns,
471 L2TP_SKB_CB(skb)->length, session->nr,
472 skb_queue_len(&session->reorder_q));
473 session->reorder_skip = 1;
474 __skb_unlink(skb, &session->reorder_q);
477 (*session->deref)(session);
481 if (L2TP_SKB_CB(skb)->has_seq) {
482 if (session->reorder_skip) {
483 l2tp_dbg(session, L2TP_MSG_SEQ,
484 "%s: advancing nr to next pkt: %u -> %u",
485 session->name, session->nr,
486 L2TP_SKB_CB(skb)->ns);
487 session->reorder_skip = 0;
488 session->nr = L2TP_SKB_CB(skb)->ns;
490 if (L2TP_SKB_CB(skb)->ns != session->nr) {
491 l2tp_dbg(session, L2TP_MSG_SEQ,
492 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
493 session->name, L2TP_SKB_CB(skb)->ns,
494 L2TP_SKB_CB(skb)->length, session->nr,
495 skb_queue_len(&session->reorder_q));
499 __skb_unlink(skb, &session->reorder_q);
501 /* Process the skb. We release the queue lock while we
502 * do so to let other contexts process the queue.
504 spin_unlock_bh(&session->reorder_q.lock);
505 l2tp_recv_dequeue_skb(session, skb);
510 spin_unlock_bh(&session->reorder_q.lock);
513 static inline int l2tp_verify_udp_checksum(struct sock *sk,
516 struct udphdr *uh = udp_hdr(skb);
517 u16 ulen = ntohs(uh->len);
520 if (sk->sk_no_check || skb_csum_unnecessary(skb))
523 #if IS_ENABLED(CONFIG_IPV6)
524 if (sk->sk_family == PF_INET6) {
526 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
529 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
530 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
531 &ipv6_hdr(skb)->daddr, ulen,
532 IPPROTO_UDP, skb->csum)) {
533 skb->ip_summed = CHECKSUM_UNNECESSARY;
536 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
537 &ipv6_hdr(skb)->daddr,
538 skb->len, IPPROTO_UDP,
543 struct inet_sock *inet;
547 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
548 ulen, IPPROTO_UDP, 0);
550 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
551 !csum_fold(csum_add(psum, skb->csum)))
556 return __skb_checksum_complete(skb);
559 /* Do receive processing of L2TP data frames. We handle both L2TPv2
560 * and L2TPv3 data frames here.
562 * L2TPv2 Data Message Header
565 * 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
566 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
567 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
568 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
569 * | Tunnel ID | Session ID |
570 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
571 * | Ns (opt) | Nr (opt) |
572 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
573 * | Offset Size (opt) | Offset pad... (opt)
574 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
576 * Data frames are marked by T=0. All other fields are the same as
577 * those in L2TP control frames.
579 * L2TPv3 Data Message Header
581 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
582 * | L2TP Session Header |
583 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
584 * | L2-Specific Sublayer |
585 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
586 * | Tunnel Payload ...
587 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
589 * L2TPv3 Session Header Over IP
592 * 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
593 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
595 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
596 * | Cookie (optional, maximum 64 bits)...
597 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
599 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
601 * L2TPv3 L2-Specific Sublayer Format
604 * 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
605 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
606 * |x|S|x|x|x|x|x|x| Sequence Number |
607 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
609 * Cookie value, sublayer format and offset (pad) are negotiated with
610 * the peer when the session is set up. Unlike L2TPv2, we do not need
611 * to parse the packet header to determine if optional fields are
614 * Caller must already have parsed the frame and determined that it is
615 * a data (not control) frame before coming here. Fields up to the
616 * session-id have already been parsed and ptr points to the data
617 * after the session-id.
619 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
620 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
621 int length, int (*payload_hook)(struct sk_buff *skb))
623 struct l2tp_tunnel *tunnel = session->tunnel;
626 struct l2tp_stats *sstats = &session->stats;
628 /* The ref count is increased since we now hold a pointer to
629 * the session. Take care to decrement the refcnt when exiting
630 * this function from now on...
632 l2tp_session_inc_refcount(session);
634 (*session->ref)(session);
636 /* Parse and check optional cookie */
637 if (session->peer_cookie_len > 0) {
638 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
639 l2tp_info(tunnel, L2TP_MSG_DATA,
640 "%s: cookie mismatch (%u/%u). Discarding.\n",
641 tunnel->name, tunnel->tunnel_id,
642 session->session_id);
643 u64_stats_update_begin(&sstats->syncp);
644 sstats->rx_cookie_discards++;
645 u64_stats_update_end(&sstats->syncp);
648 ptr += session->peer_cookie_len;
651 /* Handle the optional sequence numbers. Sequence numbers are
652 * in different places for L2TPv2 and L2TPv3.
654 * If we are the LAC, enable/disable sequence numbers under
655 * the control of the LNS. If no sequence numbers present but
656 * we were expecting them, discard frame.
659 L2TP_SKB_CB(skb)->has_seq = 0;
660 if (tunnel->version == L2TP_HDR_VER_2) {
661 if (hdrflags & L2TP_HDRFLAG_S) {
662 ns = ntohs(*(__be16 *) ptr);
664 nr = ntohs(*(__be16 *) ptr);
667 /* Store L2TP info in the skb */
668 L2TP_SKB_CB(skb)->ns = ns;
669 L2TP_SKB_CB(skb)->has_seq = 1;
671 l2tp_dbg(session, L2TP_MSG_SEQ,
672 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
673 session->name, ns, nr, session->nr);
675 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
676 u32 l2h = ntohl(*(__be32 *) ptr);
678 if (l2h & 0x40000000) {
679 ns = l2h & 0x00ffffff;
681 /* Store L2TP info in the skb */
682 L2TP_SKB_CB(skb)->ns = ns;
683 L2TP_SKB_CB(skb)->has_seq = 1;
685 l2tp_dbg(session, L2TP_MSG_SEQ,
686 "%s: recv data ns=%u, session nr=%u\n",
687 session->name, ns, session->nr);
691 /* Advance past L2-specific header, if present */
692 ptr += session->l2specific_len;
694 if (L2TP_SKB_CB(skb)->has_seq) {
695 /* Received a packet with sequence numbers. If we're the LNS,
696 * check if we sre sending sequence numbers and if not,
699 if ((!session->lns_mode) && (!session->send_seq)) {
700 l2tp_info(session, L2TP_MSG_SEQ,
701 "%s: requested to enable seq numbers by LNS\n",
703 session->send_seq = -1;
704 l2tp_session_set_header_len(session, tunnel->version);
707 /* No sequence numbers.
708 * If user has configured mandatory sequence numbers, discard.
710 if (session->recv_seq) {
711 l2tp_warn(session, L2TP_MSG_SEQ,
712 "%s: recv data has no seq numbers when required. Discarding.\n",
714 u64_stats_update_begin(&sstats->syncp);
715 sstats->rx_seq_discards++;
716 u64_stats_update_end(&sstats->syncp);
720 /* If we're the LAC and we're sending sequence numbers, the
721 * LNS has requested that we no longer send sequence numbers.
722 * If we're the LNS and we're sending sequence numbers, the
723 * LAC is broken. Discard the frame.
725 if ((!session->lns_mode) && (session->send_seq)) {
726 l2tp_info(session, L2TP_MSG_SEQ,
727 "%s: requested to disable seq numbers by LNS\n",
729 session->send_seq = 0;
730 l2tp_session_set_header_len(session, tunnel->version);
731 } else if (session->send_seq) {
732 l2tp_warn(session, L2TP_MSG_SEQ,
733 "%s: recv data has no seq numbers when required. Discarding.\n",
735 u64_stats_update_begin(&sstats->syncp);
736 sstats->rx_seq_discards++;
737 u64_stats_update_end(&sstats->syncp);
742 /* Session data offset is handled differently for L2TPv2 and
743 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
744 * the header. For L2TPv3, the offset is negotiated using AVPs
745 * in the session setup control protocol.
747 if (tunnel->version == L2TP_HDR_VER_2) {
748 /* If offset bit set, skip it. */
749 if (hdrflags & L2TP_HDRFLAG_O) {
750 offset = ntohs(*(__be16 *)ptr);
754 ptr += session->offset;
757 if (!pskb_may_pull(skb, offset))
760 __skb_pull(skb, offset);
762 /* If caller wants to process the payload before we queue the
766 if ((*payload_hook)(skb))
769 /* Prepare skb for adding to the session's reorder_q. Hold
770 * packets for max reorder_timeout or 1 second if not
773 L2TP_SKB_CB(skb)->length = length;
774 L2TP_SKB_CB(skb)->expires = jiffies +
775 (session->reorder_timeout ? session->reorder_timeout : HZ);
777 /* Add packet to the session's receive queue. Reordering is done here, if
778 * enabled. Saved L2TP protocol info is stored in skb->sb[].
780 if (L2TP_SKB_CB(skb)->has_seq) {
781 if (session->reorder_timeout != 0) {
782 /* Packet reordering enabled. Add skb to session's
783 * reorder queue, in order of ns.
785 l2tp_recv_queue_skb(session, skb);
787 /* Packet reordering disabled. Discard out-of-sequence
790 if (L2TP_SKB_CB(skb)->ns != session->nr) {
791 u64_stats_update_begin(&sstats->syncp);
792 sstats->rx_seq_discards++;
793 u64_stats_update_end(&sstats->syncp);
794 l2tp_dbg(session, L2TP_MSG_SEQ,
795 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
796 session->name, L2TP_SKB_CB(skb)->ns,
797 L2TP_SKB_CB(skb)->length, session->nr,
798 skb_queue_len(&session->reorder_q));
801 skb_queue_tail(&session->reorder_q, skb);
804 /* No sequence numbers. Add the skb to the tail of the
805 * reorder queue. This ensures that it will be
806 * delivered after all previous sequenced skbs.
808 skb_queue_tail(&session->reorder_q, skb);
811 /* Try to dequeue as many skbs from reorder_q as we can. */
812 l2tp_recv_dequeue(session);
814 l2tp_session_dec_refcount(session);
819 u64_stats_update_begin(&sstats->syncp);
821 u64_stats_update_end(&sstats->syncp);
825 (*session->deref)(session);
827 l2tp_session_dec_refcount(session);
829 EXPORT_SYMBOL(l2tp_recv_common);
831 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
832 * here. The skb is not on a list when we get here.
833 * Returns 0 if the packet was a data packet and was successfully passed on.
834 * Returns 1 if the packet was not a good data packet and could not be
835 * forwarded. All such packets are passed up to userspace to deal with.
837 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
838 int (*payload_hook)(struct sk_buff *skb))
840 struct l2tp_session *session = NULL;
841 unsigned char *ptr, *optr;
843 u32 tunnel_id, session_id;
846 struct l2tp_stats *tstats;
848 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
849 goto discard_bad_csum;
851 /* UDP always verifies the packet length. */
852 __skb_pull(skb, sizeof(struct udphdr));
855 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
856 l2tp_info(tunnel, L2TP_MSG_DATA,
857 "%s: recv short packet (len=%d)\n",
858 tunnel->name, skb->len);
862 /* Trace packet contents, if enabled */
863 if (tunnel->debug & L2TP_MSG_DATA) {
864 length = min(32u, skb->len);
865 if (!pskb_may_pull(skb, length))
868 pr_debug("%s: recv\n", tunnel->name);
869 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
872 /* Point to L2TP header */
873 optr = ptr = skb->data;
875 /* Get L2TP header flags */
876 hdrflags = ntohs(*(__be16 *) ptr);
878 /* Check protocol version */
879 version = hdrflags & L2TP_HDR_VER_MASK;
880 if (version != tunnel->version) {
881 l2tp_info(tunnel, L2TP_MSG_DATA,
882 "%s: recv protocol version mismatch: got %d expected %d\n",
883 tunnel->name, version, tunnel->version);
887 /* Get length of L2TP packet */
890 /* If type is control packet, it is handled by userspace. */
891 if (hdrflags & L2TP_HDRFLAG_T) {
892 l2tp_dbg(tunnel, L2TP_MSG_DATA,
893 "%s: recv control packet, len=%d\n",
894 tunnel->name, length);
901 if (tunnel->version == L2TP_HDR_VER_2) {
902 /* If length is present, skip it */
903 if (hdrflags & L2TP_HDRFLAG_L)
906 /* Extract tunnel and session ID */
907 tunnel_id = ntohs(*(__be16 *) ptr);
909 session_id = ntohs(*(__be16 *) ptr);
912 ptr += 2; /* skip reserved bits */
913 tunnel_id = tunnel->tunnel_id;
914 session_id = ntohl(*(__be32 *) ptr);
918 /* Find the session context */
919 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
920 if (!session || !session->recv_skb) {
921 /* Not found? Pass to userspace to deal with */
922 l2tp_info(tunnel, L2TP_MSG_DATA,
923 "%s: no session found (%u/%u). Passing up.\n",
924 tunnel->name, tunnel_id, session_id);
928 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
933 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
934 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
935 tstats = &tunnel->stats;
936 u64_stats_update_begin(&tstats->syncp);
938 u64_stats_update_end(&tstats->syncp);
944 /* Put UDP header back */
945 __skb_push(skb, sizeof(struct udphdr));
950 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
954 * >0: skb should be passed up to userspace as UDP.
956 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
958 struct l2tp_tunnel *tunnel;
960 tunnel = l2tp_sock_to_tunnel(sk);
964 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
965 tunnel->name, skb->len);
967 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
978 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
980 /************************************************************************
982 ***********************************************************************/
984 /* Build an L2TP header for the session into the buffer provided.
986 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
988 struct l2tp_tunnel *tunnel = session->tunnel;
991 u16 flags = L2TP_HDR_VER_2;
992 u32 tunnel_id = tunnel->peer_tunnel_id;
993 u32 session_id = session->peer_session_id;
995 if (session->send_seq)
996 flags |= L2TP_HDRFLAG_S;
998 /* Setup L2TP header. */
999 *bufp++ = htons(flags);
1000 *bufp++ = htons(tunnel_id);
1001 *bufp++ = htons(session_id);
1002 if (session->send_seq) {
1003 *bufp++ = htons(session->ns);
1006 session->ns &= 0xffff;
1007 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1008 session->name, session->ns);
1014 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1016 struct l2tp_tunnel *tunnel = session->tunnel;
1020 /* Setup L2TP header. The header differs slightly for UDP and
1021 * IP encapsulations. For UDP, there is 4 bytes of flags.
1023 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1024 u16 flags = L2TP_HDR_VER_3;
1025 *((__be16 *) bufp) = htons(flags);
1027 *((__be16 *) bufp) = 0;
1031 *((__be32 *) bufp) = htonl(session->peer_session_id);
1033 if (session->cookie_len) {
1034 memcpy(bufp, &session->cookie[0], session->cookie_len);
1035 bufp += session->cookie_len;
1037 if (session->l2specific_len) {
1038 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1040 if (session->send_seq) {
1041 l2h = 0x40000000 | session->ns;
1043 session->ns &= 0xffffff;
1044 l2tp_dbg(session, L2TP_MSG_SEQ,
1045 "%s: updated ns to %u\n",
1046 session->name, session->ns);
1049 *((__be32 *) bufp) = htonl(l2h);
1051 bufp += session->l2specific_len;
1053 if (session->offset)
1054 bufp += session->offset;
1059 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1060 struct flowi *fl, size_t data_len)
1062 struct l2tp_tunnel *tunnel = session->tunnel;
1063 unsigned int len = skb->len;
1065 struct l2tp_stats *tstats, *sstats;
1068 if (session->send_seq)
1069 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1070 session->name, data_len, session->ns - 1);
1072 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1073 session->name, data_len);
1075 if (session->debug & L2TP_MSG_DATA) {
1076 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1077 unsigned char *datap = skb->data + uhlen;
1079 pr_debug("%s: xmit\n", session->name);
1080 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1081 datap, min_t(size_t, 32, len - uhlen));
1084 /* Queue the packet to IP for output */
1086 #if IS_ENABLED(CONFIG_IPV6)
1087 if (skb->sk->sk_family == PF_INET6)
1088 error = inet6_csk_xmit(skb, NULL);
1091 error = ip_queue_xmit(skb, fl);
1094 tstats = &tunnel->stats;
1095 u64_stats_update_begin(&tstats->syncp);
1096 sstats = &session->stats;
1097 u64_stats_update_begin(&sstats->syncp);
1099 tstats->tx_packets++;
1100 tstats->tx_bytes += len;
1101 sstats->tx_packets++;
1102 sstats->tx_bytes += len;
1104 tstats->tx_errors++;
1105 sstats->tx_errors++;
1107 u64_stats_update_end(&tstats->syncp);
1108 u64_stats_update_end(&sstats->syncp);
1113 /* Automatically called when the skb is freed.
1115 static void l2tp_sock_wfree(struct sk_buff *skb)
1120 /* For data skbs that we transmit, we associate with the tunnel socket
1121 * but don't do accounting.
1123 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1127 skb->destructor = l2tp_sock_wfree;
1130 #if IS_ENABLED(CONFIG_IPV6)
1131 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1134 struct ipv6_pinfo *np = inet6_sk(sk);
1135 struct udphdr *uh = udp_hdr(skb);
1137 if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1138 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1139 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1140 skb->ip_summed = CHECKSUM_UNNECESSARY;
1141 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1144 uh->check = CSUM_MANGLED_0;
1146 skb->ip_summed = CHECKSUM_PARTIAL;
1147 skb->csum_start = skb_transport_header(skb) - skb->head;
1148 skb->csum_offset = offsetof(struct udphdr, check);
1149 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1150 udp_len, IPPROTO_UDP, 0);
1155 /* If caller requires the skb to have a ppp header, the header must be
1156 * inserted in the skb data before calling this function.
1158 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1160 int data_len = skb->len;
1161 struct l2tp_tunnel *tunnel = session->tunnel;
1162 struct sock *sk = tunnel->sock;
1165 struct inet_sock *inet;
1168 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1170 int ret = NET_XMIT_SUCCESS;
1172 /* Check that there's enough headroom in the skb to insert IP,
1173 * UDP and L2TP headers. If not enough, expand it to
1174 * make room. Adjust truesize.
1176 headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1178 if (skb_cow_head(skb, headroom)) {
1180 return NET_XMIT_DROP;
1184 /* Setup L2TP header */
1185 session->build_header(session, __skb_push(skb, hdr_len));
1187 /* Reset skb netfilter state */
1188 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1189 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1194 if (sock_owned_by_user(sk)) {
1196 ret = NET_XMIT_DROP;
1200 /* Get routing info from the tunnel socket */
1202 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1205 fl = &inet->cork.fl;
1206 switch (tunnel->encap) {
1207 case L2TP_ENCAPTYPE_UDP:
1208 /* Setup UDP header */
1209 __skb_push(skb, sizeof(*uh));
1210 skb_reset_transport_header(skb);
1212 uh->source = inet->inet_sport;
1213 uh->dest = inet->inet_dport;
1214 udp_len = uhlen + hdr_len + data_len;
1215 uh->len = htons(udp_len);
1218 /* Calculate UDP checksum if configured to do so */
1219 #if IS_ENABLED(CONFIG_IPV6)
1220 if (sk->sk_family == PF_INET6)
1221 l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1224 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1225 skb->ip_summed = CHECKSUM_NONE;
1226 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1227 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1228 skb->ip_summed = CHECKSUM_COMPLETE;
1229 csum = skb_checksum(skb, 0, udp_len, 0);
1230 uh->check = csum_tcpudp_magic(inet->inet_saddr,
1232 udp_len, IPPROTO_UDP, csum);
1234 uh->check = CSUM_MANGLED_0;
1236 skb->ip_summed = CHECKSUM_PARTIAL;
1237 skb->csum_start = skb_transport_header(skb) - skb->head;
1238 skb->csum_offset = offsetof(struct udphdr, check);
1239 uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1241 udp_len, IPPROTO_UDP, 0);
1245 case L2TP_ENCAPTYPE_IP:
1249 l2tp_skb_set_owner_w(skb, sk);
1251 l2tp_xmit_core(session, skb, fl, data_len);
1257 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1259 /*****************************************************************************
1260 * Tinnel and session create/destroy.
1261 *****************************************************************************/
1263 /* Tunnel socket destruct hook.
1264 * The tunnel context is deleted only when all session sockets have been
1267 static void l2tp_tunnel_destruct(struct sock *sk)
1269 struct l2tp_tunnel *tunnel;
1270 struct l2tp_net *pn;
1272 tunnel = sk->sk_user_data;
1276 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1279 /* Disable udp encapsulation */
1280 switch (tunnel->encap) {
1281 case L2TP_ENCAPTYPE_UDP:
1282 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1283 (udp_sk(sk))->encap_type = 0;
1284 (udp_sk(sk))->encap_rcv = NULL;
1286 case L2TP_ENCAPTYPE_IP:
1290 /* Remove hooks into tunnel socket */
1291 sk->sk_destruct = tunnel->old_sk_destruct;
1292 sk->sk_user_data = NULL;
1293 tunnel->sock = NULL;
1295 /* Remove the tunnel struct from the tunnel list */
1296 pn = l2tp_pernet(tunnel->l2tp_net);
1297 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1298 list_del_rcu(&tunnel->list);
1299 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1300 atomic_dec(&l2tp_tunnel_count);
1302 l2tp_tunnel_closeall(tunnel);
1303 l2tp_tunnel_dec_refcount(tunnel);
1305 /* Call the original destructor */
1306 if (sk->sk_destruct)
1307 (*sk->sk_destruct)(sk);
1312 /* When the tunnel is closed, all the attached sessions need to go too.
1314 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1317 struct hlist_node *walk;
1318 struct hlist_node *tmp;
1319 struct l2tp_session *session;
1321 BUG_ON(tunnel == NULL);
1323 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1326 write_lock_bh(&tunnel->hlist_lock);
1327 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1329 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1330 session = hlist_entry(walk, struct l2tp_session, hlist);
1332 l2tp_info(session, L2TP_MSG_CONTROL,
1333 "%s: closing session\n", session->name);
1335 hlist_del_init(&session->hlist);
1337 /* Since we should hold the sock lock while
1338 * doing any unbinding, we need to release the
1339 * lock we're holding before taking that lock.
1340 * Hold a reference to the sock so it doesn't
1341 * disappear as we're jumping between locks.
1343 if (session->ref != NULL)
1344 (*session->ref)(session);
1346 write_unlock_bh(&tunnel->hlist_lock);
1348 if (tunnel->version != L2TP_HDR_VER_2) {
1349 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1351 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1352 hlist_del_init_rcu(&session->global_hlist);
1353 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1357 if (session->session_close != NULL)
1358 (*session->session_close)(session);
1360 if (session->deref != NULL)
1361 (*session->deref)(session);
1363 write_lock_bh(&tunnel->hlist_lock);
1365 /* Now restart from the beginning of this hash
1366 * chain. We always remove a session from the
1367 * list so we are guaranteed to make forward
1373 write_unlock_bh(&tunnel->hlist_lock);
1376 /* Really kill the tunnel.
1377 * Come here only when all sessions have been cleared from the tunnel.
1379 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1381 BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1382 BUG_ON(tunnel->sock != NULL);
1383 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1384 kfree_rcu(tunnel, rcu);
1387 /* Workqueue tunnel deletion function */
1388 static void l2tp_tunnel_del_work(struct work_struct *work)
1390 struct l2tp_tunnel *tunnel = NULL;
1391 struct socket *sock = NULL;
1392 struct sock *sk = NULL;
1394 tunnel = container_of(work, struct l2tp_tunnel, del_work);
1395 sk = l2tp_tunnel_sock_lookup(tunnel);
1399 sock = sk->sk_socket;
1402 /* If the tunnel socket was created directly by the kernel, use the
1403 * sk_* API to release the socket now. Otherwise go through the
1404 * inet_* layer to shut the socket down, and let userspace close it.
1405 * In either case the tunnel resources are freed in the socket
1406 * destructor when the tunnel socket goes away.
1408 if (sock->file == NULL) {
1409 kernel_sock_shutdown(sock, SHUT_RDWR);
1410 sk_release_kernel(sk);
1412 inet_shutdown(sock, 2);
1415 l2tp_tunnel_sock_put(sk);
1418 /* Create a socket for the tunnel, if one isn't set up by
1419 * userspace. This is used for static tunnels where there is no
1420 * managing L2TP daemon.
1422 * Since we don't want these sockets to keep a namespace alive by
1423 * themselves, we drop the socket's namespace refcount after creation.
1424 * These sockets are freed when the namespace exits using the pernet
1427 static int l2tp_tunnel_sock_create(struct net *net,
1430 struct l2tp_tunnel_cfg *cfg,
1431 struct socket **sockp)
1434 struct socket *sock = NULL;
1435 struct sockaddr_in udp_addr = {0};
1436 struct sockaddr_l2tpip ip_addr = {0};
1437 #if IS_ENABLED(CONFIG_IPV6)
1438 struct sockaddr_in6 udp6_addr = {0};
1439 struct sockaddr_l2tpip6 ip6_addr = {0};
1442 switch (cfg->encap) {
1443 case L2TP_ENCAPTYPE_UDP:
1444 #if IS_ENABLED(CONFIG_IPV6)
1445 if (cfg->local_ip6 && cfg->peer_ip6) {
1446 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1450 sk_change_net(sock->sk, net);
1452 udp6_addr.sin6_family = AF_INET6;
1453 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1454 sizeof(udp6_addr.sin6_addr));
1455 udp6_addr.sin6_port = htons(cfg->local_udp_port);
1456 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1461 udp6_addr.sin6_family = AF_INET6;
1462 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1463 sizeof(udp6_addr.sin6_addr));
1464 udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1465 err = kernel_connect(sock,
1466 (struct sockaddr *) &udp6_addr,
1467 sizeof(udp6_addr), 0);
1473 err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1477 sk_change_net(sock->sk, net);
1479 udp_addr.sin_family = AF_INET;
1480 udp_addr.sin_addr = cfg->local_ip;
1481 udp_addr.sin_port = htons(cfg->local_udp_port);
1482 err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1487 udp_addr.sin_family = AF_INET;
1488 udp_addr.sin_addr = cfg->peer_ip;
1489 udp_addr.sin_port = htons(cfg->peer_udp_port);
1490 err = kernel_connect(sock,
1491 (struct sockaddr *) &udp_addr,
1492 sizeof(udp_addr), 0);
1497 if (!cfg->use_udp_checksums)
1498 sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1502 case L2TP_ENCAPTYPE_IP:
1503 #if IS_ENABLED(CONFIG_IPV6)
1504 if (cfg->local_ip6 && cfg->peer_ip6) {
1505 err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1506 IPPROTO_L2TP, &sock);
1510 sk_change_net(sock->sk, net);
1512 ip6_addr.l2tp_family = AF_INET6;
1513 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1514 sizeof(ip6_addr.l2tp_addr));
1515 ip6_addr.l2tp_conn_id = tunnel_id;
1516 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1521 ip6_addr.l2tp_family = AF_INET6;
1522 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1523 sizeof(ip6_addr.l2tp_addr));
1524 ip6_addr.l2tp_conn_id = peer_tunnel_id;
1525 err = kernel_connect(sock,
1526 (struct sockaddr *) &ip6_addr,
1527 sizeof(ip6_addr), 0);
1533 err = sock_create_kern(AF_INET, SOCK_DGRAM,
1534 IPPROTO_L2TP, &sock);
1538 sk_change_net(sock->sk, net);
1540 ip_addr.l2tp_family = AF_INET;
1541 ip_addr.l2tp_addr = cfg->local_ip;
1542 ip_addr.l2tp_conn_id = tunnel_id;
1543 err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1548 ip_addr.l2tp_family = AF_INET;
1549 ip_addr.l2tp_addr = cfg->peer_ip;
1550 ip_addr.l2tp_conn_id = peer_tunnel_id;
1551 err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1552 sizeof(ip_addr), 0);
1564 if ((err < 0) && sock) {
1565 kernel_sock_shutdown(sock, SHUT_RDWR);
1566 sk_release_kernel(sock->sk);
1573 static struct lock_class_key l2tp_socket_class;
1575 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)
1577 struct l2tp_tunnel *tunnel = NULL;
1579 struct socket *sock = NULL;
1580 struct sock *sk = NULL;
1581 struct l2tp_net *pn;
1582 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1584 /* Get the tunnel socket from the fd, which was opened by
1585 * the userspace L2TP daemon. If not specified, create a
1589 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1594 sock = sockfd_lookup(fd, &err);
1596 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1597 tunnel_id, fd, err);
1602 /* Reject namespace mismatches */
1603 if (!net_eq(sock_net(sock->sk), net)) {
1604 pr_err("tunl %u: netns mismatch\n", tunnel_id);
1615 /* Quick sanity checks */
1617 case L2TP_ENCAPTYPE_UDP:
1618 err = -EPROTONOSUPPORT;
1619 if (sk->sk_protocol != IPPROTO_UDP) {
1620 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1621 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1625 case L2TP_ENCAPTYPE_IP:
1626 err = -EPROTONOSUPPORT;
1627 if (sk->sk_protocol != IPPROTO_L2TP) {
1628 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1629 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1635 /* Check if this socket has already been prepped */
1636 tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1637 if (tunnel != NULL) {
1638 /* This socket has already been prepped */
1643 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1644 if (tunnel == NULL) {
1649 tunnel->version = version;
1650 tunnel->tunnel_id = tunnel_id;
1651 tunnel->peer_tunnel_id = peer_tunnel_id;
1652 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1654 tunnel->magic = L2TP_TUNNEL_MAGIC;
1655 sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1656 rwlock_init(&tunnel->hlist_lock);
1658 /* The net we belong to */
1659 tunnel->l2tp_net = net;
1660 pn = l2tp_pernet(net);
1663 tunnel->debug = cfg->debug;
1665 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1666 tunnel->encap = encap;
1667 if (encap == L2TP_ENCAPTYPE_UDP) {
1668 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1669 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1670 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1671 #if IS_ENABLED(CONFIG_IPV6)
1672 if (sk->sk_family == PF_INET6)
1673 udpv6_encap_enable();
1679 sk->sk_user_data = tunnel;
1681 /* Hook on the tunnel socket destructor so that we can cleanup
1682 * if the tunnel socket goes away.
1684 tunnel->old_sk_destruct = sk->sk_destruct;
1685 sk->sk_destruct = &l2tp_tunnel_destruct;
1688 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1690 sk->sk_allocation = GFP_ATOMIC;
1692 /* Init delete workqueue struct */
1693 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1695 /* Add tunnel to our list */
1696 INIT_LIST_HEAD(&tunnel->list);
1697 atomic_inc(&l2tp_tunnel_count);
1699 /* Bump the reference count. The tunnel context is deleted
1700 * only when this drops to zero. Must be done before list insertion
1702 l2tp_tunnel_inc_refcount(tunnel);
1703 spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1704 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1705 spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1712 /* If tunnel's socket was created by the kernel, it doesn't
1715 if (sock && sock->file)
1720 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1722 /* This function is used by the netlink TUNNEL_DELETE command.
1724 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1726 return (false == queue_work(l2tp_wq, &tunnel->del_work));
1728 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1730 /* Really kill the session.
1732 void l2tp_session_free(struct l2tp_session *session)
1734 struct l2tp_tunnel *tunnel;
1736 BUG_ON(atomic_read(&session->ref_count) != 0);
1738 tunnel = session->tunnel;
1739 if (tunnel != NULL) {
1740 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1742 /* Delete the session from the hash */
1743 write_lock_bh(&tunnel->hlist_lock);
1744 hlist_del_init(&session->hlist);
1745 write_unlock_bh(&tunnel->hlist_lock);
1747 /* Unlink from the global hash if not L2TPv2 */
1748 if (tunnel->version != L2TP_HDR_VER_2) {
1749 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1751 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1752 hlist_del_init_rcu(&session->global_hlist);
1753 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1757 if (session->session_id != 0)
1758 atomic_dec(&l2tp_session_count);
1760 sock_put(tunnel->sock);
1762 /* This will delete the tunnel context if this
1763 * is the last session on the tunnel.
1765 session->tunnel = NULL;
1766 l2tp_tunnel_dec_refcount(tunnel);
1773 EXPORT_SYMBOL_GPL(l2tp_session_free);
1775 /* This function is used by the netlink SESSION_DELETE command and by
1778 int l2tp_session_delete(struct l2tp_session *session)
1780 if (session->session_close != NULL)
1781 (*session->session_close)(session);
1783 l2tp_session_dec_refcount(session);
1787 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1790 /* We come here whenever a session's send_seq, cookie_len or
1791 * l2specific_len parameters are set.
1793 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1795 if (version == L2TP_HDR_VER_2) {
1796 session->hdr_len = 6;
1797 if (session->send_seq)
1798 session->hdr_len += 4;
1800 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1801 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1802 session->hdr_len += 4;
1807 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)
1809 struct l2tp_session *session;
1811 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1812 if (session != NULL) {
1813 session->magic = L2TP_SESSION_MAGIC;
1814 session->tunnel = tunnel;
1816 session->session_id = session_id;
1817 session->peer_session_id = peer_session_id;
1820 sprintf(&session->name[0], "sess %u/%u",
1821 tunnel->tunnel_id, session->session_id);
1823 skb_queue_head_init(&session->reorder_q);
1825 INIT_HLIST_NODE(&session->hlist);
1826 INIT_HLIST_NODE(&session->global_hlist);
1828 /* Inherit debug options from tunnel */
1829 session->debug = tunnel->debug;
1832 session->pwtype = cfg->pw_type;
1833 session->debug = cfg->debug;
1834 session->mtu = cfg->mtu;
1835 session->mru = cfg->mru;
1836 session->send_seq = cfg->send_seq;
1837 session->recv_seq = cfg->recv_seq;
1838 session->lns_mode = cfg->lns_mode;
1839 session->reorder_timeout = cfg->reorder_timeout;
1840 session->offset = cfg->offset;
1841 session->l2specific_type = cfg->l2specific_type;
1842 session->l2specific_len = cfg->l2specific_len;
1843 session->cookie_len = cfg->cookie_len;
1844 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1845 session->peer_cookie_len = cfg->peer_cookie_len;
1846 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1849 if (tunnel->version == L2TP_HDR_VER_2)
1850 session->build_header = l2tp_build_l2tpv2_header;
1852 session->build_header = l2tp_build_l2tpv3_header;
1854 l2tp_session_set_header_len(session, tunnel->version);
1856 /* Bump the reference count. The session context is deleted
1857 * only when this drops to zero.
1859 l2tp_session_inc_refcount(session);
1860 l2tp_tunnel_inc_refcount(tunnel);
1862 /* Ensure tunnel socket isn't deleted */
1863 sock_hold(tunnel->sock);
1865 /* Add session to the tunnel's hash list */
1866 write_lock_bh(&tunnel->hlist_lock);
1867 hlist_add_head(&session->hlist,
1868 l2tp_session_id_hash(tunnel, session_id));
1869 write_unlock_bh(&tunnel->hlist_lock);
1871 /* And to the global session list if L2TPv3 */
1872 if (tunnel->version != L2TP_HDR_VER_2) {
1873 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1875 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1876 hlist_add_head_rcu(&session->global_hlist,
1877 l2tp_session_id_hash_2(pn, session_id));
1878 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1881 /* Ignore management session in session count value */
1882 if (session->session_id != 0)
1883 atomic_inc(&l2tp_session_count);
1888 EXPORT_SYMBOL_GPL(l2tp_session_create);
1890 /*****************************************************************************
1892 *****************************************************************************/
1894 static __net_init int l2tp_init_net(struct net *net)
1896 struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1899 INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1900 spin_lock_init(&pn->l2tp_tunnel_list_lock);
1902 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1903 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1905 spin_lock_init(&pn->l2tp_session_hlist_lock);
1910 static __net_exit void l2tp_exit_net(struct net *net)
1912 struct l2tp_net *pn = l2tp_pernet(net);
1913 struct l2tp_tunnel *tunnel = NULL;
1916 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1917 (void)l2tp_tunnel_delete(tunnel);
1919 rcu_read_unlock_bh();
1922 static struct pernet_operations l2tp_net_ops = {
1923 .init = l2tp_init_net,
1924 .exit = l2tp_exit_net,
1926 .size = sizeof(struct l2tp_net),
1929 static int __init l2tp_init(void)
1933 rc = register_pernet_device(&l2tp_net_ops);
1937 l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
1939 pr_err("alloc_workqueue failed\n");
1944 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1950 static void __exit l2tp_exit(void)
1952 unregister_pernet_device(&l2tp_net_ops);
1954 destroy_workqueue(l2tp_wq);
1959 module_init(l2tp_init);
1960 module_exit(l2tp_exit);
1962 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1963 MODULE_DESCRIPTION("L2TP core");
1964 MODULE_LICENSE("GPL");
1965 MODULE_VERSION(L2TP_DRV_VERSION);