l2tp_core.c 46.1 KB
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/*
 * L2TP core.
 *
 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
 *
 * This file contains some code of the original L2TPv2 pppol2tp
 * driver, which has the following copyright:
 *
 * Authors:	Martijn van Oosterhout <kleptog@svana.org>
 *		James Chapman (jchapman@katalix.com)
 * Contributors:
 *		Michal Ostrowski <mostrows@speakeasy.net>
 *		Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
 *		David S. Miller (davem@redhat.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/uaccess.h>

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/jiffies.h>

#include <linux/netdevice.h>
#include <linux/net.h>
#include <linux/inetdevice.h>
#include <linux/skbuff.h>
#include <linux/init.h>
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#include <linux/in.h>
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#include <linux/ip.h>
#include <linux/udp.h>
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#include <linux/l2tp.h>
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#include <linux/hash.h>
#include <linux/sort.h>
#include <linux/file.h>
#include <linux/nsproxy.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/udp.h>
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#include <net/inet_common.h>
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#include <net/xfrm.h>
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#include <net/protocol.h>
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#include <asm/byteorder.h>
#include <asm/atomic.h>

#include "l2tp_core.h"

#define L2TP_DRV_VERSION	"V2.0"

/* L2TP header constants */
#define L2TP_HDRFLAG_T	   0x8000
#define L2TP_HDRFLAG_L	   0x4000
#define L2TP_HDRFLAG_S	   0x0800
#define L2TP_HDRFLAG_O	   0x0200
#define L2TP_HDRFLAG_P	   0x0100

#define L2TP_HDR_VER_MASK  0x000F
#define L2TP_HDR_VER_2	   0x0002
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#define L2TP_HDR_VER_3	   0x0003
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/* L2TPv3 default L2-specific sublayer */
#define L2TP_SLFLAG_S	   0x40000000
#define L2TP_SL_SEQ_MASK   0x00ffffff

#define L2TP_HDR_SIZE_SEQ		10
#define L2TP_HDR_SIZE_NOSEQ		6

/* Default trace flags */
#define L2TP_DEFAULT_DEBUG_FLAGS	0

#define PRINTK(_mask, _type, _lvl, _fmt, args...)			\
	do {								\
		if ((_mask) & (_type))					\
			printk(_lvl "L2TP: " _fmt, ##args);		\
	} while (0)

/* Private data stored for received packets in the skb.
 */
struct l2tp_skb_cb {
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	u32			ns;
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	u16			has_seq;
	u16			length;
	unsigned long		expires;
};

#define L2TP_SKB_CB(skb)	((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])

static atomic_t l2tp_tunnel_count;
static atomic_t l2tp_session_count;

/* per-net private data for this module */
static unsigned int l2tp_net_id;
struct l2tp_net {
	struct list_head l2tp_tunnel_list;
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	spinlock_t l2tp_tunnel_list_lock;
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	struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
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	spinlock_t l2tp_session_hlist_lock;
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};

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static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);

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static inline struct l2tp_net *l2tp_pernet(struct net *net)
{
	BUG_ON(!net);

	return net_generic(net, l2tp_net_id);
}

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/* Tunnel reference counts. Incremented per session that is added to
 * the tunnel.
 */
static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
{
	atomic_inc(&tunnel->ref_count);
}

static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
{
	if (atomic_dec_and_test(&tunnel->ref_count))
		l2tp_tunnel_free(tunnel);
}
#ifdef L2TP_REFCNT_DEBUG
#define l2tp_tunnel_inc_refcount(_t) do { \
		printk(KERN_DEBUG "l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
		l2tp_tunnel_inc_refcount_1(_t);				\
	} while (0)
#define l2tp_tunnel_dec_refcount(_t) do { \
		printk(KERN_DEBUG "l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
		l2tp_tunnel_dec_refcount_1(_t);				\
	} while (0)
#else
#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
#endif

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/* Session hash global list for L2TPv3.
 * The session_id SHOULD be random according to RFC3931, but several
 * L2TP implementations use incrementing session_ids.  So we do a real
 * hash on the session_id, rather than a simple bitmask.
 */
static inline struct hlist_head *
l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
{
	return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];

}

/* Lookup a session by id in the global session list
 */
static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
{
	struct l2tp_net *pn = l2tp_pernet(net);
	struct hlist_head *session_list =
		l2tp_session_id_hash_2(pn, session_id);
	struct l2tp_session *session;
	struct hlist_node *walk;

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	rcu_read_lock_bh();
	hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
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		if (session->session_id == session_id) {
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			rcu_read_unlock_bh();
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			return session;
		}
	}
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	rcu_read_unlock_bh();
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	return NULL;
}

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/* Session hash list.
 * The session_id SHOULD be random according to RFC2661, but several
 * L2TP implementations (Cisco and Microsoft) use incrementing
 * session_ids.  So we do a real hash on the session_id, rather than a
 * simple bitmask.
 */
static inline struct hlist_head *
l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
{
	return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
}

/* Lookup a session by id
 */
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struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
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{
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	struct hlist_head *session_list;
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	struct l2tp_session *session;
	struct hlist_node *walk;

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	/* In L2TPv3, session_ids are unique over all tunnels and we
	 * sometimes need to look them up before we know the
	 * tunnel.
	 */
	if (tunnel == NULL)
		return l2tp_session_find_2(net, session_id);

	session_list = l2tp_session_id_hash(tunnel, session_id);
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	read_lock_bh(&tunnel->hlist_lock);
	hlist_for_each_entry(session, walk, session_list, hlist) {
		if (session->session_id == session_id) {
			read_unlock_bh(&tunnel->hlist_lock);
			return session;
		}
	}
	read_unlock_bh(&tunnel->hlist_lock);

	return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_find);

struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
{
	int hash;
	struct hlist_node *walk;
	struct l2tp_session *session;
	int count = 0;

	read_lock_bh(&tunnel->hlist_lock);
	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
		hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
			if (++count > nth) {
				read_unlock_bh(&tunnel->hlist_lock);
				return session;
			}
		}
	}

	read_unlock_bh(&tunnel->hlist_lock);

	return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_find_nth);

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/* Lookup a session by interface name.
 * This is very inefficient but is only used by management interfaces.
 */
struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
{
	struct l2tp_net *pn = l2tp_pernet(net);
	int hash;
	struct hlist_node *walk;
	struct l2tp_session *session;

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	rcu_read_lock_bh();
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	for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
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		hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
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			if (!strcmp(session->ifname, ifname)) {
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				rcu_read_unlock_bh();
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				return session;
			}
		}
	}

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	rcu_read_unlock_bh();
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	return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);

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/* Lookup a tunnel by id
 */
struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
{
	struct l2tp_tunnel *tunnel;
	struct l2tp_net *pn = l2tp_pernet(net);

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	rcu_read_lock_bh();
	list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
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		if (tunnel->tunnel_id == tunnel_id) {
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			rcu_read_unlock_bh();
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			return tunnel;
		}
	}
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	rcu_read_unlock_bh();
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	return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_find);

struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
{
	struct l2tp_net *pn = l2tp_pernet(net);
	struct l2tp_tunnel *tunnel;
	int count = 0;

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	rcu_read_lock_bh();
	list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
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		if (++count > nth) {
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			rcu_read_unlock_bh();
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			return tunnel;
		}
	}

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	rcu_read_unlock_bh();
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	return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);

/*****************************************************************************
 * Receive data handling
 *****************************************************************************/

/* Queue a skb in order. We come here only if the skb has an L2TP sequence
 * number.
 */
static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
{
	struct sk_buff *skbp;
	struct sk_buff *tmp;
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	u32 ns = L2TP_SKB_CB(skb)->ns;
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	spin_lock_bh(&session->reorder_q.lock);
	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
		if (L2TP_SKB_CB(skbp)->ns > ns) {
			__skb_queue_before(&session->reorder_q, skbp, skb);
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
			       "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
			       session->name, ns, L2TP_SKB_CB(skbp)->ns,
			       skb_queue_len(&session->reorder_q));
			session->stats.rx_oos_packets++;
			goto out;
		}
	}

	__skb_queue_tail(&session->reorder_q, skb);

out:
	spin_unlock_bh(&session->reorder_q.lock);
}

/* Dequeue a single skb.
 */
static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
{
	struct l2tp_tunnel *tunnel = session->tunnel;
	int length = L2TP_SKB_CB(skb)->length;

	/* We're about to requeue the skb, so return resources
	 * to its current owner (a socket receive buffer).
	 */
	skb_orphan(skb);

	tunnel->stats.rx_packets++;
	tunnel->stats.rx_bytes += length;
	session->stats.rx_packets++;
	session->stats.rx_bytes += length;

	if (L2TP_SKB_CB(skb)->has_seq) {
		/* Bump our Nr */
		session->nr++;
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		if (tunnel->version == L2TP_HDR_VER_2)
			session->nr &= 0xffff;
		else
			session->nr &= 0xffffff;

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		PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
		       "%s: updated nr to %hu\n", session->name, session->nr);
	}

	/* call private receive handler */
	if (session->recv_skb != NULL)
		(*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
	else
		kfree_skb(skb);

	if (session->deref)
		(*session->deref)(session);
}

/* Dequeue skbs from the session's reorder_q, subject to packet order.
 * Skbs that have been in the queue for too long are simply discarded.
 */
static void l2tp_recv_dequeue(struct l2tp_session *session)
{
	struct sk_buff *skb;
	struct sk_buff *tmp;

	/* If the pkt at the head of the queue has the nr that we
	 * expect to send up next, dequeue it and any other
	 * in-sequence packets behind it.
	 */
	spin_lock_bh(&session->reorder_q.lock);
	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
		if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
			session->stats.rx_seq_discards++;
			session->stats.rx_errors++;
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
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			       "%s: oos pkt %u len %d discarded (too old), "
			       "waiting for %u, reorder_q_len=%d\n",
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			       session->name, L2TP_SKB_CB(skb)->ns,
			       L2TP_SKB_CB(skb)->length, session->nr,
			       skb_queue_len(&session->reorder_q));
			__skb_unlink(skb, &session->reorder_q);
			kfree_skb(skb);
			if (session->deref)
				(*session->deref)(session);
			continue;
		}

		if (L2TP_SKB_CB(skb)->has_seq) {
			if (L2TP_SKB_CB(skb)->ns != session->nr) {
				PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
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				       "%s: holding oos pkt %u len %d, "
				       "waiting for %u, reorder_q_len=%d\n",
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				       session->name, L2TP_SKB_CB(skb)->ns,
				       L2TP_SKB_CB(skb)->length, session->nr,
				       skb_queue_len(&session->reorder_q));
				goto out;
			}
		}
		__skb_unlink(skb, &session->reorder_q);

		/* Process the skb. We release the queue lock while we
		 * do so to let other contexts process the queue.
		 */
		spin_unlock_bh(&session->reorder_q.lock);
		l2tp_recv_dequeue_skb(session, skb);
		spin_lock_bh(&session->reorder_q.lock);
	}

out:
	spin_unlock_bh(&session->reorder_q.lock);
}

static inline int l2tp_verify_udp_checksum(struct sock *sk,
					   struct sk_buff *skb)
{
	struct udphdr *uh = udp_hdr(skb);
	u16 ulen = ntohs(uh->len);
	struct inet_sock *inet;
	__wsum psum;

	if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
		return 0;

	inet = inet_sk(sk);
	psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
				  IPPROTO_UDP, 0);

	if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
	    !csum_fold(csum_add(psum, skb->csum)))
		return 0;

	skb->csum = psum;

	return __skb_checksum_complete(skb);
}

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/* Do receive processing of L2TP data frames. We handle both L2TPv2
 * and L2TPv3 data frames here.
 *
 * L2TPv2 Data Message Header
 *
 *  0                   1                   2                   3
 *  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
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |           Tunnel ID           |           Session ID          |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |             Ns (opt)          |             Nr (opt)          |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |      Offset Size (opt)        |    Offset pad... (opt)
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Data frames are marked by T=0. All other fields are the same as
 * those in L2TP control frames.
 *
 * L2TPv3 Data Message Header
 *
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      L2TP Session Header                      |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      L2-Specific Sublayer                     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                        Tunnel Payload                      ...
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * L2TPv3 Session Header Over IP
 *
 *  0                   1                   2                   3
 *  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
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                           Session ID                          |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |               Cookie (optional, maximum 64 bits)...
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *                                                                 |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * L2TPv3 L2-Specific Sublayer Format
 *
 *  0                   1                   2                   3
 *  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
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Cookie value, sublayer format and offset (pad) are negotiated with
 * the peer when the session is set up. Unlike L2TPv2, we do not need
 * to parse the packet header to determine if optional fields are
 * present.
 *
 * Caller must already have parsed the frame and determined that it is
 * a data (not control) frame before coming here. Fields up to the
 * session-id have already been parsed and ptr points to the data
 * after the session-id.
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 */
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void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
		      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
		      int length, int (*payload_hook)(struct sk_buff *skb))
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{
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	struct l2tp_tunnel *tunnel = session->tunnel;
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	int offset;
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	u32 ns, nr;
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	/* The ref count is increased since we now hold a pointer to
	 * the session. Take care to decrement the refcnt when exiting
	 * this function from now on...
	 */
	l2tp_session_inc_refcount(session);
	if (session->ref)
		(*session->ref)(session);

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	/* Parse and check optional cookie */
	if (session->peer_cookie_len > 0) {
		if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
			PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
			       "%s: cookie mismatch (%u/%u). Discarding.\n",
			       tunnel->name, tunnel->tunnel_id, session->session_id);
			session->stats.rx_cookie_discards++;
			goto discard;
		}
		ptr += session->peer_cookie_len;
	}

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	/* Handle the optional sequence numbers. Sequence numbers are
	 * in different places for L2TPv2 and L2TPv3.
	 *
	 * If we are the LAC, enable/disable sequence numbers under
	 * the control of the LNS.  If no sequence numbers present but
	 * we were expecting them, discard frame.
	 */
	ns = nr = 0;
	L2TP_SKB_CB(skb)->has_seq = 0;
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	if (tunnel->version == L2TP_HDR_VER_2) {
		if (hdrflags & L2TP_HDRFLAG_S) {
			ns = ntohs(*(__be16 *) ptr);
			ptr += 2;
			nr = ntohs(*(__be16 *) ptr);
			ptr += 2;
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			/* Store L2TP info in the skb */
			L2TP_SKB_CB(skb)->ns = ns;
			L2TP_SKB_CB(skb)->has_seq = 1;
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			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
			       "%s: recv data ns=%u, nr=%u, session nr=%u\n",
			       session->name, ns, nr, session->nr);
		}
	} else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
		u32 l2h = ntohl(*(__be32 *) ptr);

		if (l2h & 0x40000000) {
			ns = l2h & 0x00ffffff;

			/* Store L2TP info in the skb */
			L2TP_SKB_CB(skb)->ns = ns;
			L2TP_SKB_CB(skb)->has_seq = 1;

			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
			       "%s: recv data ns=%u, session nr=%u\n",
			       session->name, ns, session->nr);
		}
593 594
	}

595 596 597
	/* Advance past L2-specific header, if present */
	ptr += session->l2specific_len;

598 599 600 601 602 603 604 605 606 607
	if (L2TP_SKB_CB(skb)->has_seq) {
		/* Received a packet with sequence numbers. If we're the LNS,
		 * check if we sre sending sequence numbers and if not,
		 * configure it so.
		 */
		if ((!session->lns_mode) && (!session->send_seq)) {
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
			       "%s: requested to enable seq numbers by LNS\n",
			       session->name);
			session->send_seq = -1;
608
			l2tp_session_set_header_len(session, tunnel->version);
609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631
		}
	} else {
		/* No sequence numbers.
		 * If user has configured mandatory sequence numbers, discard.
		 */
		if (session->recv_seq) {
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
			       "%s: recv data has no seq numbers when required. "
			       "Discarding\n", session->name);
			session->stats.rx_seq_discards++;
			goto discard;
		}

		/* If we're the LAC and we're sending sequence numbers, the
		 * LNS has requested that we no longer send sequence numbers.
		 * If we're the LNS and we're sending sequence numbers, the
		 * LAC is broken. Discard the frame.
		 */
		if ((!session->lns_mode) && (session->send_seq)) {
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
			       "%s: requested to disable seq numbers by LNS\n",
			       session->name);
			session->send_seq = 0;
632
			l2tp_session_set_header_len(session, tunnel->version);
633 634 635 636 637 638 639 640 641
		} else if (session->send_seq) {
			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
			       "%s: recv data has no seq numbers when required. "
			       "Discarding\n", session->name);
			session->stats.rx_seq_discards++;
			goto discard;
		}
	}

642 643 644 645 646 647 648 649 650 651 652 653 654
	/* Session data offset is handled differently for L2TPv2 and
	 * L2TPv3. For L2TPv2, there is an optional 16-bit value in
	 * the header. For L2TPv3, the offset is negotiated using AVPs
	 * in the session setup control protocol.
	 */
	if (tunnel->version == L2TP_HDR_VER_2) {
		/* If offset bit set, skip it. */
		if (hdrflags & L2TP_HDRFLAG_O) {
			offset = ntohs(*(__be16 *)ptr);
			ptr += 2 + offset;
		}
	} else
		ptr += session->offset;
655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692

	offset = ptr - optr;
	if (!pskb_may_pull(skb, offset))
		goto discard;

	__skb_pull(skb, offset);

	/* If caller wants to process the payload before we queue the
	 * packet, do so now.
	 */
	if (payload_hook)
		if ((*payload_hook)(skb))
			goto discard;

	/* Prepare skb for adding to the session's reorder_q.  Hold
	 * packets for max reorder_timeout or 1 second if not
	 * reordering.
	 */
	L2TP_SKB_CB(skb)->length = length;
	L2TP_SKB_CB(skb)->expires = jiffies +
		(session->reorder_timeout ? session->reorder_timeout : HZ);

	/* Add packet to the session's receive queue. Reordering is done here, if
	 * enabled. Saved L2TP protocol info is stored in skb->sb[].
	 */
	if (L2TP_SKB_CB(skb)->has_seq) {
		if (session->reorder_timeout != 0) {
			/* Packet reordering enabled. Add skb to session's
			 * reorder queue, in order of ns.
			 */
			l2tp_recv_queue_skb(session, skb);
		} else {
			/* Packet reordering disabled. Discard out-of-sequence
			 * packets
			 */
			if (L2TP_SKB_CB(skb)->ns != session->nr) {
				session->stats.rx_seq_discards++;
				PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
693 694
				       "%s: oos pkt %u len %d discarded, "
				       "waiting for %u, reorder_q_len=%d\n",
695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714
				       session->name, L2TP_SKB_CB(skb)->ns,
				       L2TP_SKB_CB(skb)->length, session->nr,
				       skb_queue_len(&session->reorder_q));
				goto discard;
			}
			skb_queue_tail(&session->reorder_q, skb);
		}
	} else {
		/* No sequence numbers. Add the skb to the tail of the
		 * reorder queue. This ensures that it will be
		 * delivered after all previous sequenced skbs.
		 */
		skb_queue_tail(&session->reorder_q, skb);
	}

	/* Try to dequeue as many skbs from reorder_q as we can. */
	l2tp_recv_dequeue(session);

	l2tp_session_dec_refcount(session);

715
	return;
716 717 718 719 720 721 722 723 724

discard:
	session->stats.rx_errors++;
	kfree_skb(skb);

	if (session->deref)
		(*session->deref)(session);

	l2tp_session_dec_refcount(session);
725 726 727 728 729 730 731 732 733
}
EXPORT_SYMBOL(l2tp_recv_common);

/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 * here. The skb is not on a list when we get here.
 * Returns 0 if the packet was a data packet and was successfully passed on.
 * Returns 1 if the packet was not a good data packet and could not be
 * forwarded.  All such packets are passed up to userspace to deal with.
 */
734 735
static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
			      int (*payload_hook)(struct sk_buff *skb))
736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820
{
	struct l2tp_session *session = NULL;
	unsigned char *ptr, *optr;
	u16 hdrflags;
	u32 tunnel_id, session_id;
	int offset;
	u16 version;
	int length;

	if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
		goto discard_bad_csum;

	/* UDP always verifies the packet length. */
	__skb_pull(skb, sizeof(struct udphdr));

	/* Short packet? */
	if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
		       "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
		goto error;
	}

	/* Point to L2TP header */
	optr = ptr = skb->data;

	/* Trace packet contents, if enabled */
	if (tunnel->debug & L2TP_MSG_DATA) {
		length = min(32u, skb->len);
		if (!pskb_may_pull(skb, length))
			goto error;

		printk(KERN_DEBUG "%s: recv: ", tunnel->name);

		offset = 0;
		do {
			printk(" %02X", ptr[offset]);
		} while (++offset < length);

		printk("\n");
	}

	/* Get L2TP header flags */
	hdrflags = ntohs(*(__be16 *) ptr);

	/* Check protocol version */
	version = hdrflags & L2TP_HDR_VER_MASK;
	if (version != tunnel->version) {
		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
		       "%s: recv protocol version mismatch: got %d expected %d\n",
		       tunnel->name, version, tunnel->version);
		goto error;
	}

	/* Get length of L2TP packet */
	length = skb->len;

	/* If type is control packet, it is handled by userspace. */
	if (hdrflags & L2TP_HDRFLAG_T) {
		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
		       "%s: recv control packet, len=%d\n", tunnel->name, length);
		goto error;
	}

	/* Skip flags */
	ptr += 2;

	if (tunnel->version == L2TP_HDR_VER_2) {
		/* If length is present, skip it */
		if (hdrflags & L2TP_HDRFLAG_L)
			ptr += 2;

		/* Extract tunnel and session ID */
		tunnel_id = ntohs(*(__be16 *) ptr);
		ptr += 2;
		session_id = ntohs(*(__be16 *) ptr);
		ptr += 2;
	} else {
		ptr += 2;	/* skip reserved bits */
		tunnel_id = tunnel->tunnel_id;
		session_id = ntohl(*(__be32 *) ptr);
		ptr += 4;
	}

	/* Find the session context */
	session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
821
	if (!session || !session->recv_skb) {
822 823 824 825 826 827 828 829
		/* Not found? Pass to userspace to deal with */
		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
		       "%s: no session found (%u/%u). Passing up.\n",
		       tunnel->name, tunnel_id, session_id);
		goto error;
	}

	l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883

	return 0;

discard_bad_csum:
	LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
	UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
	tunnel->stats.rx_errors++;
	kfree_skb(skb);

	return 0;

error:
	/* Put UDP header back */
	__skb_push(skb, sizeof(struct udphdr));

	return 1;
}

/* UDP encapsulation receive handler. See net/ipv4/udp.c.
 * Return codes:
 * 0 : success.
 * <0: error
 * >0: skb should be passed up to userspace as UDP.
 */
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
	struct l2tp_tunnel *tunnel;

	tunnel = l2tp_sock_to_tunnel(sk);
	if (tunnel == NULL)
		goto pass_up;

	PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
	       "%s: received %d bytes\n", tunnel->name, skb->len);

	if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
		goto pass_up_put;

	sock_put(sk);
	return 0;

pass_up_put:
	sock_put(sk);
pass_up:
	return 1;
}
EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);

/************************************************************************
 * Transmit handling
 ***********************************************************************/

/* Build an L2TP header for the session into the buffer provided.
 */
884
static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
885
{
886
	struct l2tp_tunnel *tunnel = session->tunnel;
887
	__be16 *bufp = buf;
888
	__be16 *optr = buf;
889 890 891 892 893 894 895 896 897 898 899 900 901 902 903
	u16 flags = L2TP_HDR_VER_2;
	u32 tunnel_id = tunnel->peer_tunnel_id;
	u32 session_id = session->peer_session_id;

	if (session->send_seq)
		flags |= L2TP_HDRFLAG_S;

	/* Setup L2TP header. */
	*bufp++ = htons(flags);
	*bufp++ = htons(tunnel_id);
	*bufp++ = htons(session_id);
	if (session->send_seq) {
		*bufp++ = htons(session->ns);
		*bufp++ = 0;
		session->ns++;
904
		session->ns &= 0xffff;
905
		PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
906
		       "%s: updated ns to %u\n", session->name, session->ns);
907
	}
908 909

	return bufp - optr;
910 911
}

912
static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
913
{
914
	struct l2tp_tunnel *tunnel = session->tunnel;
915 916 917
	char *bufp = buf;
	char *optr = bufp;

918 919 920 921 922 923 924 925 926 927 928
	/* Setup L2TP header. The header differs slightly for UDP and
	 * IP encapsulations. For UDP, there is 4 bytes of flags.
	 */
	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
		u16 flags = L2TP_HDR_VER_3;
		*((__be16 *) bufp) = htons(flags);
		bufp += 2;
		*((__be16 *) bufp) = 0;
		bufp += 2;
	}

929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951
	*((__be32 *) bufp) = htonl(session->peer_session_id);
	bufp += 4;
	if (session->cookie_len) {
		memcpy(bufp, &session->cookie[0], session->cookie_len);
		bufp += session->cookie_len;
	}
	if (session->l2specific_len) {
		if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
			u32 l2h = 0;
			if (session->send_seq) {
				l2h = 0x40000000 | session->ns;
				session->ns++;
				session->ns &= 0xffffff;
				PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
				       "%s: updated ns to %u\n", session->name, session->ns);
			}

			*((__be32 *) bufp) = htonl(l2h);
		}
		bufp += session->l2specific_len;
	}
	if (session->offset)
		bufp += session->offset;
952

953
	return bufp - optr;
954 955
}

956
static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
957
			  struct flowi *fl, size_t data_len)
958 959 960 961 962 963 964 965
{
	struct l2tp_tunnel *tunnel = session->tunnel;
	unsigned int len = skb->len;
	int error;

	/* Debug */
	if (session->send_seq)
		PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
966
		       "%s: send %Zd bytes, ns=%u\n", session->name,
967 968 969 970 971 972 973
		       data_len, session->ns - 1);
	else
		PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
		       "%s: send %Zd bytes\n", session->name, data_len);

	if (session->debug & L2TP_MSG_DATA) {
		int i;
974 975
		int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
		unsigned char *datap = skb->data + uhlen;
976 977

		printk(KERN_DEBUG "%s: xmit:", session->name);
978
		for (i = 0; i < (len - uhlen); i++) {
979 980 981 982 983 984 985 986 987 988
			printk(" %02X", *datap++);
			if (i == 31) {
				printk(" ...");
				break;
			}
		}
		printk("\n");
	}

	/* Queue the packet to IP for output */
989
	skb->local_df = 1;
990
	error = ip_queue_xmit(skb, fl);
991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028

	/* Update stats */
	if (error >= 0) {
		tunnel->stats.tx_packets++;
		tunnel->stats.tx_bytes += len;
		session->stats.tx_packets++;
		session->stats.tx_bytes += len;
	} else {
		tunnel->stats.tx_errors++;
		session->stats.tx_errors++;
	}

	return 0;
}

/* Automatically called when the skb is freed.
 */
static void l2tp_sock_wfree(struct sk_buff *skb)
{
	sock_put(skb->sk);
}

/* For data skbs that we transmit, we associate with the tunnel socket
 * but don't do accounting.
 */
static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
{
	sock_hold(sk);
	skb->sk = sk;
	skb->destructor = l2tp_sock_wfree;
}

/* If caller requires the skb to have a ppp header, the header must be
 * inserted in the skb data before calling this function.
 */
int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
{
	int data_len = skb->len;
1029 1030
	struct l2tp_tunnel *tunnel = session->tunnel;
	struct sock *sk = tunnel->sock;
1031
	struct flowi *fl;
1032 1033 1034 1035 1036 1037
	struct udphdr *uh;
	struct inet_sock *inet;
	__wsum csum;
	int old_headroom;
	int new_headroom;
	int headroom;
1038 1039
	int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
	int udp_len;
1040 1041 1042 1043 1044 1045

	/* Check that there's enough headroom in the skb to insert IP,
	 * UDP and L2TP headers. If not enough, expand it to
	 * make room. Adjust truesize.
	 */
	headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1046
		uhlen + hdr_len;
1047 1048 1049 1050 1051 1052 1053 1054 1055
	old_headroom = skb_headroom(skb);
	if (skb_cow_head(skb, headroom))
		goto abort;

	new_headroom = skb_headroom(skb);
	skb_orphan(skb);
	skb->truesize += new_headroom - old_headroom;

	/* Setup L2TP header */
1056
	session->build_header(session, __skb_push(skb, hdr_len));
1057

1058
	/* Reset skb netfilter state */
1059 1060 1061 1062 1063
	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
			      IPSKB_REROUTED);
	nf_reset(skb);

1064 1065 1066 1067 1068 1069
	bh_lock_sock(sk);
	if (sock_owned_by_user(sk)) {
		dev_kfree_skb(skb);
		goto out_unlock;
	}

1070 1071 1072 1073
	/* Get routing info from the tunnel socket */
	skb_dst_drop(skb);
	skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));

1074 1075
	inet = inet_sk(sk);
	fl = &inet->cork.fl;
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111
	switch (tunnel->encap) {
	case L2TP_ENCAPTYPE_UDP:
		/* Setup UDP header */
		__skb_push(skb, sizeof(*uh));
		skb_reset_transport_header(skb);
		uh = udp_hdr(skb);
		uh->source = inet->inet_sport;
		uh->dest = inet->inet_dport;
		udp_len = uhlen + hdr_len + data_len;
		uh->len = htons(udp_len);
		uh->check = 0;

		/* Calculate UDP checksum if configured to do so */
		if (sk->sk_no_check == UDP_CSUM_NOXMIT)
			skb->ip_summed = CHECKSUM_NONE;
		else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
			 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
			skb->ip_summed = CHECKSUM_COMPLETE;
			csum = skb_checksum(skb, 0, udp_len, 0);
			uh->check = csum_tcpudp_magic(inet->inet_saddr,
						      inet->inet_daddr,
						      udp_len, IPPROTO_UDP, csum);
			if (uh->check == 0)
				uh->check = CSUM_MANGLED_0;
		} else {
			skb->ip_summed = CHECKSUM_PARTIAL;
			skb->csum_start = skb_transport_header(skb) - skb->head;
			skb->csum_offset = offsetof(struct udphdr, check);
			uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
						       inet->inet_daddr,
						       udp_len, IPPROTO_UDP, 0);
		}
		break;

	case L2TP_ENCAPTYPE_IP:
		break;
1112 1113
	}

1114 1115
	l2tp_skb_set_owner_w(skb, sk);

1116
	l2tp_xmit_core(session, skb, fl, data_len);
1117 1118
out_unlock:
	bh_unlock_sock(sk);
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132

abort:
	return 0;
}
EXPORT_SYMBOL_GPL(l2tp_xmit_skb);

/*****************************************************************************
 * Tinnel and session create/destroy.
 *****************************************************************************/

/* Tunnel socket destruct hook.
 * The tunnel context is deleted only when all session sockets have been
 * closed.
 */
1133
static void l2tp_tunnel_destruct(struct sock *sk)
1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
{
	struct l2tp_tunnel *tunnel;

	tunnel = sk->sk_user_data;
	if (tunnel == NULL)
		goto end;

	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
	       "%s: closing...\n", tunnel->name);

	/* Close all sessions */
	l2tp_tunnel_closeall(tunnel);

1147 1148 1149 1150 1151 1152 1153 1154 1155
	switch (tunnel->encap) {
	case L2TP_ENCAPTYPE_UDP:
		/* No longer an encapsulation socket. See net/ipv4/udp.c */
		(udp_sk(sk))->encap_type = 0;
		(udp_sk(sk))->encap_rcv = NULL;
		break;
	case L2TP_ENCAPTYPE_IP:
		break;
	}
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174

	/* Remove hooks into tunnel socket */
	tunnel->sock = NULL;
	sk->sk_destruct = tunnel->old_sk_destruct;
	sk->sk_user_data = NULL;

	/* Call the original destructor */
	if (sk->sk_destruct)
		(*sk->sk_destruct)(sk);

	/* We're finished with the socket */
	l2tp_tunnel_dec_refcount(tunnel);

end:
	return;
}

/* When the tunnel is closed, all the attached sessions need to go too.
 */
1175
static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208
{
	int hash;
	struct hlist_node *walk;
	struct hlist_node *tmp;
	struct l2tp_session *session;

	BUG_ON(tunnel == NULL);

	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
	       "%s: closing all sessions...\n", tunnel->name);

	write_lock_bh(&tunnel->hlist_lock);
	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
again:
		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
			session = hlist_entry(walk, struct l2tp_session, hlist);

			PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
			       "%s: closing session\n", session->name);

			hlist_del_init(&session->hlist);

			/* Since we should hold the sock lock while
			 * doing any unbinding, we need to release the
			 * lock we're holding before taking that lock.
			 * Hold a reference to the sock so it doesn't
			 * disappear as we're jumping between locks.
			 */
			if (session->ref != NULL)
				(*session->ref)(session);

			write_unlock_bh(&tunnel->hlist_lock);

1209 1210 1211
			if (tunnel->version != L2TP_HDR_VER_2) {
				struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

J
James Chapman 已提交
1212 1213 1214 1215
				spin_lock_bh(&pn->l2tp_session_hlist_lock);
				hlist_del_init_rcu(&session->global_hlist);
				spin_unlock_bh(&pn->l2tp_session_hlist_lock);
				synchronize_rcu();
1216 1217
			}

1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239
			if (session->session_close != NULL)
				(*session->session_close)(session);

			if (session->deref != NULL)
				(*session->deref)(session);

			write_lock_bh(&tunnel->hlist_lock);

			/* Now restart from the beginning of this hash
			 * chain.  We always remove a session from the
			 * list so we are guaranteed to make forward
			 * progress.
			 */
			goto again;
		}
	}
	write_unlock_bh(&tunnel->hlist_lock);
}

/* Really kill the tunnel.
 * Come here only when all sessions have been cleared from the tunnel.
 */
1240
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1241 1242 1243 1244 1245 1246 1247 1248 1249 1250
{
	struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

	BUG_ON(atomic_read(&tunnel->ref_count) != 0);
	BUG_ON(tunnel->sock != NULL);

	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
	       "%s: free...\n", tunnel->name);

	/* Remove from tunnel list */
J
James Chapman 已提交
1251 1252 1253 1254
	spin_lock_bh(&pn->l2tp_tunnel_list_lock);
	list_del_rcu(&tunnel->list);
	spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
	synchronize_rcu();
1255 1256 1257 1258 1259

	atomic_dec(&l2tp_tunnel_count);
	kfree(tunnel);
}

1260 1261 1262 1263 1264 1265 1266 1267 1268
/* Create a socket for the tunnel, if one isn't set up by
 * userspace. This is used for static tunnels where there is no
 * managing L2TP daemon.
 */
static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
{
	int err = -EINVAL;
	struct sockaddr_in udp_addr;
	struct sockaddr_l2tpip ip_addr;
1269
	struct socket *sock = NULL;
1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335

	switch (cfg->encap) {
	case L2TP_ENCAPTYPE_UDP:
		err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
		if (err < 0)
			goto out;

		sock = *sockp;

		memset(&udp_addr, 0, sizeof(udp_addr));
		udp_addr.sin_family = AF_INET;
		udp_addr.sin_addr = cfg->local_ip;
		udp_addr.sin_port = htons(cfg->local_udp_port);
		err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr));
		if (err < 0)
			goto out;

		udp_addr.sin_family = AF_INET;
		udp_addr.sin_addr = cfg->peer_ip;
		udp_addr.sin_port = htons(cfg->peer_udp_port);
		err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0);
		if (err < 0)
			goto out;

		if (!cfg->use_udp_checksums)
			sock->sk->sk_no_check = UDP_CSUM_NOXMIT;

		break;

	case L2TP_ENCAPTYPE_IP:
		err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP, sockp);
		if (err < 0)
			goto out;

		sock = *sockp;

		memset(&ip_addr, 0, sizeof(ip_addr));
		ip_addr.l2tp_family = AF_INET;
		ip_addr.l2tp_addr = cfg->local_ip;
		ip_addr.l2tp_conn_id = tunnel_id;
		err = kernel_bind(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr));
		if (err < 0)
			goto out;

		ip_addr.l2tp_family = AF_INET;
		ip_addr.l2tp_addr = cfg->peer_ip;
		ip_addr.l2tp_conn_id = peer_tunnel_id;
		err = kernel_connect(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr), 0);
		if (err < 0)
			goto out;

		break;

	default:
		goto out;
	}

out:
	if ((err < 0) && sock) {
		sock_release(sock);
		*sockp = NULL;
	}

	return err;
}

1336 1337 1338 1339 1340 1341 1342
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)
{
	struct l2tp_tunnel *tunnel = NULL;
	int err;
	struct socket *sock = NULL;
	struct sock *sk = NULL;
	struct l2tp_net *pn;
1343
	enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1344 1345

	/* Get the tunnel socket from the fd, which was opened by
1346 1347
	 * the userspace L2TP daemon. If not specified, create a
	 * kernel socket.
1348
	 */
1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360
	if (fd < 0) {
		err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
		if (err < 0)
			goto err;
	} else {
		err = -EBADF;
		sock = sockfd_lookup(fd, &err);
		if (!sock) {
			printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
			       tunnel_id, fd, err);
			goto err;
		}
1361 1362 1363 1364
	}

	sk = sock->sk;

1365 1366 1367
	if (cfg != NULL)
		encap = cfg->encap;

1368
	/* Quick sanity checks */
1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385
	switch (encap) {
	case L2TP_ENCAPTYPE_UDP:
		err = -EPROTONOSUPPORT;
		if (sk->sk_protocol != IPPROTO_UDP) {
			printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
			       tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
			goto err;
		}
		break;
	case L2TP_ENCAPTYPE_IP:
		err = -EPROTONOSUPPORT;
		if (sk->sk_protocol != IPPROTO_L2TP) {
			printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
			       tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
			goto err;
		}
		break;
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414
	}

	/* Check if this socket has already been prepped */
	tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
	if (tunnel != NULL) {
		/* This socket has already been prepped */
		err = -EBUSY;
		goto err;
	}

	tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
	if (tunnel == NULL) {
		err = -ENOMEM;
		goto err;
	}

	tunnel->version = version;
	tunnel->tunnel_id = tunnel_id;
	tunnel->peer_tunnel_id = peer_tunnel_id;
	tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;

	tunnel->magic = L2TP_TUNNEL_MAGIC;
	sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
	rwlock_init(&tunnel->hlist_lock);

	/* The net we belong to */
	tunnel->l2tp_net = net;
	pn = l2tp_pernet(net);

1415
	if (cfg != NULL)
1416 1417 1418
		tunnel->debug = cfg->debug;

	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1419 1420 1421 1422 1423 1424
	tunnel->encap = encap;
	if (encap == L2TP_ENCAPTYPE_UDP) {
		/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
		udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
		udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
	}
1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437

	sk->sk_user_data = tunnel;

	/* Hook on the tunnel socket destructor so that we can cleanup
	 * if the tunnel socket goes away.
	 */
	tunnel->old_sk_destruct = sk->sk_destruct;
	sk->sk_destruct = &l2tp_tunnel_destruct;
	tunnel->sock = sk;
	sk->sk_allocation = GFP_ATOMIC;

	/* Add tunnel to our list */
	INIT_LIST_HEAD(&tunnel->list);
J
James Chapman 已提交
1438 1439 1440 1441
	spin_lock_bh(&pn->l2tp_tunnel_list_lock);
	list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
	spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
	synchronize_rcu();
1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453
	atomic_inc(&l2tp_tunnel_count);

	/* Bump the reference count. The tunnel context is deleted
	 * only when this drops to zero.
	 */
	l2tp_tunnel_inc_refcount(tunnel);

	err = 0;
err:
	if (tunnelp)
		*tunnelp = tunnel;

1454 1455 1456 1457
	/* If tunnel's socket was created by the kernel, it doesn't
	 *  have a file.
	 */
	if (sock && sock->file)
1458 1459 1460 1461 1462 1463
		sockfd_put(sock);

	return err;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_create);

1464 1465 1466 1467 1468
/* This function is used by the netlink TUNNEL_DELETE command.
 */
int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
{
	int err = 0;
1469
	struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
1470 1471 1472 1473 1474

	/* Force the tunnel socket to close. This will eventually
	 * cause the tunnel to be deleted via the normal socket close
	 * mechanisms when userspace closes the tunnel socket.
	 */
1475 1476 1477 1478 1479 1480 1481 1482 1483 1484
	if (sock != NULL) {
		err = inet_shutdown(sock, 2);

		/* If the tunnel's socket was created by the kernel,
		 * close the socket here since the socket was not
		 * created by userspace.
		 */
		if (sock->file == NULL)
			err = inet_release(sock);
	}
1485 1486 1487 1488 1489

	return err;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);

1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506
/* Really kill the session.
 */
void l2tp_session_free(struct l2tp_session *session)
{
	struct l2tp_tunnel *tunnel;

	BUG_ON(atomic_read(&session->ref_count) != 0);

	tunnel = session->tunnel;
	if (tunnel != NULL) {
		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

		/* Delete the session from the hash */
		write_lock_bh(&tunnel->hlist_lock);
		hlist_del_init(&session->hlist);
		write_unlock_bh(&tunnel->hlist_lock);

1507 1508 1509 1510
		/* Unlink from the global hash if not L2TPv2 */
		if (tunnel->version != L2TP_HDR_VER_2) {
			struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

J
James Chapman 已提交
1511 1512 1513 1514
			spin_lock_bh(&pn->l2tp_session_hlist_lock);
			hlist_del_init_rcu(&session->global_hlist);
			spin_unlock_bh(&pn->l2tp_session_hlist_lock);
			synchronize_rcu();
1515 1516
		}

1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
		if (session->session_id != 0)
			atomic_dec(&l2tp_session_count);

		sock_put(tunnel->sock);

		/* This will delete the tunnel context if this
		 * is the last session on the tunnel.
		 */
		session->tunnel = NULL;
		l2tp_tunnel_dec_refcount(tunnel);
	}

	kfree(session);

	return;
}
EXPORT_SYMBOL_GPL(l2tp_session_free);

1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549
/* This function is used by the netlink SESSION_DELETE command and by
   pseudowire modules.
 */
int l2tp_session_delete(struct l2tp_session *session)
{
	if (session->session_close != NULL)
		(*session->session_close)(session);

	l2tp_session_dec_refcount(session);

	return 0;
}
EXPORT_SYMBOL_GPL(l2tp_session_delete);


1550 1551 1552
/* We come here whenever a session's send_seq, cookie_len or
 * l2specific_len parameters are set.
 */
1553
static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1554 1555 1556 1557 1558 1559
{
	if (version == L2TP_HDR_VER_2) {
		session->hdr_len = 6;
		if (session->send_seq)
			session->hdr_len += 4;
	} else {
1560 1561 1562
		session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
		if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
			session->hdr_len += 4;
1563 1564 1565 1566
	}

}

1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577
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)
{
	struct l2tp_session *session;

	session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
	if (session != NULL) {
		session->magic = L2TP_SESSION_MAGIC;
		session->tunnel = tunnel;

		session->session_id = session_id;
		session->peer_session_id = peer_session_id;
1578
		session->nr = 1;
1579 1580 1581 1582 1583 1584 1585

		sprintf(&session->name[0], "sess %u/%u",
			tunnel->tunnel_id, session->session_id);

		skb_queue_head_init(&session->reorder_q);

		INIT_HLIST_NODE(&session->hlist);
1586
		INIT_HLIST_NODE(&session->global_hlist);
1587 1588 1589 1590 1591

		/* Inherit debug options from tunnel */
		session->debug = tunnel->debug;

		if (cfg) {
1592
			session->pwtype = cfg->pw_type;
1593 1594 1595 1596 1597 1598
			session->debug = cfg->debug;
			session->mtu = cfg->mtu;
			session->mru = cfg->mru;
			session->send_seq = cfg->send_seq;
			session->recv_seq = cfg->recv_seq;
			session->lns_mode = cfg->lns_mode;
1599 1600 1601 1602 1603 1604 1605 1606
			session->reorder_timeout = cfg->reorder_timeout;
			session->offset = cfg->offset;
			session->l2specific_type = cfg->l2specific_type;
			session->l2specific_len = cfg->l2specific_len;
			session->cookie_len = cfg->cookie_len;
			memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
			session->peer_cookie_len = cfg->peer_cookie_len;
			memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1607 1608
		}

1609 1610 1611 1612 1613 1614 1615
		if (tunnel->version == L2TP_HDR_VER_2)
			session->build_header = l2tp_build_l2tpv2_header;
		else
			session->build_header = l2tp_build_l2tpv3_header;

		l2tp_session_set_header_len(session, tunnel->version);

1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630
		/* Bump the reference count. The session context is deleted
		 * only when this drops to zero.
		 */
		l2tp_session_inc_refcount(session);
		l2tp_tunnel_inc_refcount(tunnel);

		/* Ensure tunnel socket isn't deleted */
		sock_hold(tunnel->sock);

		/* Add session to the tunnel's hash list */
		write_lock_bh(&tunnel->hlist_lock);
		hlist_add_head(&session->hlist,
			       l2tp_session_id_hash(tunnel, session_id));
		write_unlock_bh(&tunnel->hlist_lock);

1631 1632 1633 1634
		/* And to the global session list if L2TPv3 */
		if (tunnel->version != L2TP_HDR_VER_2) {
			struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

J
James Chapman 已提交
1635 1636 1637 1638 1639
			spin_lock_bh(&pn->l2tp_session_hlist_lock);
			hlist_add_head_rcu(&session->global_hlist,
					   l2tp_session_id_hash_2(pn, session_id));
			spin_unlock_bh(&pn->l2tp_session_hlist_lock);
			synchronize_rcu();
1640 1641
		}

1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656
		/* Ignore management session in session count value */
		if (session->session_id != 0)
			atomic_inc(&l2tp_session_count);
	}

	return session;
}
EXPORT_SYMBOL_GPL(l2tp_session_create);

/*****************************************************************************
 * Init and cleanup
 *****************************************************************************/

static __net_init int l2tp_init_net(struct net *net)
{
J
Jiri Pirko 已提交
1657
	struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1658
	int hash;
1659 1660

	INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
J
James Chapman 已提交
1661
	spin_lock_init(&pn->l2tp_tunnel_list_lock);
1662

1663 1664 1665
	for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
		INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);

J
James Chapman 已提交
1666
	spin_lock_init(&pn->l2tp_session_hlist_lock);
1667

1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703
	return 0;
}

static struct pernet_operations l2tp_net_ops = {
	.init = l2tp_init_net,
	.id   = &l2tp_net_id,
	.size = sizeof(struct l2tp_net),
};

static int __init l2tp_init(void)
{
	int rc = 0;

	rc = register_pernet_device(&l2tp_net_ops);
	if (rc)
		goto out;

	printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);

out:
	return rc;
}

static void __exit l2tp_exit(void)
{
	unregister_pernet_device(&l2tp_net_ops);
}

module_init(l2tp_init);
module_exit(l2tp_exit);

MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP core");
MODULE_LICENSE("GPL");
MODULE_VERSION(L2TP_DRV_VERSION);