l2tp: Split pppol2tp patch into separate l2tp and ppp parts

This patch splits the pppol2tp driver into separate L2TP and PPP parts
to prepare for L2TPv3 support. In L2TPv3, protocols other than PPP can
be carried, so this split creates a common L2TP core that will handle
the common L2TP bits which protocol support modules such as PPP will
use.

Note that the existing pppol2tp module is split into l2tp_core and
l2tp_ppp by this change.

There are no feature changes here. Internally, however, there are
significant changes, mostly to handle the separation of PPP-specific
data from the L2TP session and to provide hooks in the core for
modules like PPP to access.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/Kconfig

@@ -3158,17 +3158,12 @@ config PPPOATM
 
 config PPPOL2TP
 	tristate "PPP over L2TP (EXPERIMENTAL)"
-	depends on EXPERIMENTAL && PPP && INET
+	depends on EXPERIMENTAL && L2TP && PPP
 	help
 	  Support for PPP-over-L2TP socket family. L2TP is a protocol
 	  used by ISPs and enterprises to tunnel PPP traffic over UDP
 	  tunnels. L2TP is replacing PPTP for VPN uses.
 
-	  This kernel component handles only L2TP data packets: a
-	  userland daemon handles L2TP the control protocol (tunnel
-	  and session setup). One such daemon is OpenL2TP
-	  (http://openl2tp.sourceforge.net/).
-
 config SLIP
 	tristate "SLIP (serial line) support"
 	---help---

include/linux/if_pppol2tp.h

@@ -2,7 +2,7 @@
  * Linux PPP over L2TP (PPPoL2TP) Socket Implementation (RFC 2661)
  *
  * This file supplies definitions required by the PPP over L2TP driver
- * (pppol2tp.c).  All version information wrt this file is located in pppol2tp.c
+ * (l2tp_ppp.c).  All version information wrt this file is located in l2tp_ppp.c
  *
  * License:
  *		This program is free software; you can redistribute it and/or

net/Kconfig

@@ -186,6 +186,7 @@ source "net/sctp/Kconfig"
 source "net/rds/Kconfig"
 source "net/tipc/Kconfig"
 source "net/atm/Kconfig"
+source "net/l2tp/Kconfig"
 source "net/802/Kconfig"
 source "net/bridge/Kconfig"
 source "net/dsa/Kconfig"

net/Makefile

@@ -40,7 +40,7 @@ obj-$(CONFIG_BT)		+= bluetooth/
 obj-$(CONFIG_SUNRPC)		+= sunrpc/
 obj-$(CONFIG_AF_RXRPC)		+= rxrpc/
 obj-$(CONFIG_ATM)		+= atm/
-obj-$(CONFIG_PPPOL2TP)		+= l2tp/
+obj-$(CONFIG_L2TP)		+= l2tp/
 obj-$(CONFIG_DECNET)		+= decnet/
 obj-$(CONFIG_ECONET)		+= econet/
 obj-$(CONFIG_PHONET)		+= phonet/

net/l2tp/Kconfig

@@ -0,0 +1,28 @@
+#
+# Layer Two Tunneling Protocol (L2TP)
+#
+
+menuconfig L2TP
+	tristate "Layer Two Tunneling Protocol (L2TP)"
+	depends on INET
+	---help---
+	  Layer Two Tunneling Protocol
+
+	  From RFC 2661 <http://www.ietf.org/rfc/rfc2661.txt>.
+
+	  L2TP facilitates the tunneling of packets across an
+	  intervening network in a way that is as transparent as
+	  possible to both end-users and applications.
+
+	  L2TP is often used to tunnel PPP traffic over IP
+	  tunnels. One IP tunnel may carry thousands of individual PPP
+	  connections. L2TP is also used as a VPN protocol, popular
+	  with home workers to connect to their offices.
+
+	  The kernel component handles only L2TP data packets: a
+	  userland daemon handles L2TP the control protocol (tunnel
+	  and session setup). One such daemon is OpenL2TP
+	  (http://openl2tp.org/).
+
+	  If you don't need L2TP, say N. To compile all L2TP code as
+	  modules, choose M here.

net/l2tp/Makefile

@@ -2,4 +2,7 @@
 # Makefile for the L2TP.
 #
 
-obj-$(CONFIG_PPPOL2TP) += pppol2tp.o
+obj-$(CONFIG_L2TP) += l2tp_core.o
+
+# Build l2tp as modules if L2TP is M
+obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o

net/l2tp/l2tp_core.h

@@ -0,0 +1,254 @@
+/*
+ * L2TP internal definitions.
+ *
+ * Copyright (c) 2008,2009 Katalix Systems Ltd
+ *
+ * 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.
+ */
+
+#ifndef _L2TP_CORE_H_
+#define _L2TP_CORE_H_
+
+/* Just some random numbers */
+#define L2TP_TUNNEL_MAGIC	0x42114DDA
+#define L2TP_SESSION_MAGIC	0x0C04EB7D
+
+#define L2TP_HASH_BITS	4
+#define L2TP_HASH_SIZE	(1 << L2TP_HASH_BITS)
+
+/* Debug message categories for the DEBUG socket option */
+enum {
+	L2TP_MSG_DEBUG		= (1 << 0),	/* verbose debug (if
+						 * compiled in) */
+	L2TP_MSG_CONTROL	= (1 << 1),	/* userspace - kernel
+						 * interface */
+	L2TP_MSG_SEQ		= (1 << 2),	/* sequence numbers */
+	L2TP_MSG_DATA		= (1 << 3),	/* data packets */
+};
+
+struct sk_buff;
+
+struct l2tp_stats {
+	u64			tx_packets;
+	u64			tx_bytes;
+	u64			tx_errors;
+	u64			rx_packets;
+	u64			rx_bytes;
+	u64			rx_seq_discards;
+	u64			rx_oos_packets;
+	u64			rx_errors;
+};
+
+struct l2tp_tunnel;
+
+/* Describes a session. Contains information to determine incoming
+ * packets and transmit outgoing ones.
+ */
+struct l2tp_session_cfg {
+	unsigned		data_seq:2;	/* data sequencing level
+						 * 0 => none, 1 => IP only,
+						 * 2 => all
+						 */
+	unsigned		recv_seq:1;	/* expect receive packets with
+						 * sequence numbers? */
+	unsigned		send_seq:1;	/* send packets with sequence
+						 * numbers? */
+	unsigned		lns_mode:1;	/* behave as LNS? LAC enables
+						 * sequence numbers under
+						 * control of LNS. */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	int			offset;		/* offset to payload */
+	int			reorder_timeout; /* configured reorder timeout
+						  * (in jiffies) */
+	int			mtu;
+	int			mru;
+	int			hdr_len;
+};
+
+struct l2tp_session {
+	int			magic;		/* should be
+						 * L2TP_SESSION_MAGIC */
+
+	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel
+						 * context */
+	u32			session_id;
+	u32			peer_session_id;
+	u16			nr;		/* session NR state (receive) */
+	u16			ns;		/* session NR state (send) */
+	struct sk_buff_head	reorder_q;	/* receive reorder queue */
+	struct hlist_node	hlist;		/* Hash list node */
+	atomic_t		ref_count;
+
+	char			name[32];	/* for logging */
+	unsigned		data_seq:2;	/* data sequencing level
+						 * 0 => none, 1 => IP only,
+						 * 2 => all
+						 */
+	unsigned		recv_seq:1;	/* expect receive packets with
+						 * sequence numbers? */
+	unsigned		send_seq:1;	/* send packets with sequence
+						 * numbers? */
+	unsigned		lns_mode:1;	/* behave as LNS? LAC enables
+						 * sequence numbers under
+						 * control of LNS. */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	int			reorder_timeout; /* configured reorder timeout
+						  * (in jiffies) */
+	int			mtu;
+	int			mru;
+	int			hdr_len;
+	struct l2tp_stats	stats;
+
+	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
+	void (*session_close)(struct l2tp_session *session);
+	void (*ref)(struct l2tp_session *session);
+	void (*deref)(struct l2tp_session *session);
+
+	uint8_t			priv[0];	/* private data */
+};
+
+/* Describes the tunnel. It contains info to track all the associated
+ * sessions so incoming packets can be sorted out
+ */
+struct l2tp_tunnel_cfg {
+	int			debug;		/* bitmask of debug message
+						 * categories */
+};
+
+struct l2tp_tunnel {
+	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
+	rwlock_t		hlist_lock;	/* protect session_hlist */
+	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
+						/* hashed list of sessions,
+						 * hashed by id */
+	u32			tunnel_id;
+	u32			peer_tunnel_id;
+	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
+
+	char			name[20];	/* for logging */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	int			hdr_len;
+	struct l2tp_stats	stats;
+
+	struct list_head	list;		/* Keep a list of all tunnels */
+	struct net		*l2tp_net;	/* the net we belong to */
+
+	atomic_t		ref_count;
+
+	int (*recv_payload_hook)(struct sk_buff *skb);
+	void (*old_sk_destruct)(struct sock *);
+	struct sock		*sock;		/* Parent socket */
+	int			fd;
+
+	uint8_t			priv[0];	/* private data */
+};
+
+static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
+{
+	return &tunnel->priv[0];
+}
+
+static inline void *l2tp_session_priv(struct l2tp_session *session)
+{
+	return &session->priv[0];
+}
+
+static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
+{
+	struct l2tp_tunnel *tunnel;
+
+	if (sk == NULL)
+		return NULL;
+
+	sock_hold(sk);
+	tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
+	if (tunnel == NULL) {
+		sock_put(sk);
+		goto out;
+	}
+
+	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+
+out:
+	return tunnel;
+}
+
+extern struct l2tp_session *l2tp_session_find(struct l2tp_tunnel *tunnel, u32 session_id);
+extern struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth);
+extern struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
+extern struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);
+
+extern 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);
+extern 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);
+extern void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
+extern void l2tp_session_free(struct l2tp_session *session);
+extern int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, int (*payload_hook)(struct sk_buff *skb));
+extern int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
+
+extern void l2tp_build_l2tp_header(struct l2tp_session *session, void *buf);
+extern int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len);
+extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len);
+extern void l2tp_tunnel_destruct(struct sock *sk);
+extern void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
+
+/* 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
+
+/* Session reference counts. Incremented when code obtains a reference
+ * to a session.
+ */
+static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
+{
+	atomic_inc(&session->ref_count);
+}
+
+static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
+{
+	if (atomic_dec_and_test(&session->ref_count))
+		l2tp_session_free(session);
+}
+
+#ifdef L2TP_REFCNT_DEBUG
+#define l2tp_session_inc_refcount(_s) do { \
+		printk(KERN_DEBUG "l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_s)->name, atomic_read(&_s->ref_count)); \
+		l2tp_session_inc_refcount_1(_s);				\
+	} while (0)
+#define l2tp_session_dec_refcount(_s) do { \
+		printk(KERN_DEBUG "l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_s)->name, atomic_read(&_s->ref_count)); \
+		l2tp_session_dec_refcount_1(_s);				\
+	} while (0)
+#else
+#define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
+#define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
+#endif
+
+#endif /* _L2TP_CORE_H_ */