l2tp: Add l2tp support

Based on earlier implementation by James Chapman. But instead of
dragging in all of libnl, use existing libnetlink infrastructure.

include/linux/l2tp.h

+/*
+ * L2TP-over-IP socket for L2TPv3.
+ *
+ * Author: James Chapman <jchapman@katalix.com>
+ */
+
+#ifndef _LINUX_L2TP_H_
+#define _LINUX_L2TP_H_
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <netinet/in.h>
+
+#define IPPROTO_L2TP		115
+
+/**
+ * struct sockaddr_l2tpip - the sockaddr structure for L2TP-over-IP sockets
+ * @l2tp_family:  address family number AF_L2TPIP.
+ * @l2tp_addr:    protocol specific address information
+ * @l2tp_conn_id: connection id of tunnel
+ */
+#define __SOCK_SIZE__	16		/* sizeof(struct sockaddr)	*/
+struct sockaddr_l2tpip {
+	/* The first fields must match struct sockaddr_in */
+	__kernel_sa_family_t l2tp_family; /* AF_INET */
+	__be16		l2tp_unused;	/* INET port number (unused) */
+	struct in_addr	l2tp_addr;	/* Internet address */
+
+	__u32		l2tp_conn_id;	/* Connection ID of tunnel */
+
+	/* Pad to size of `struct sockaddr'. */
+	unsigned char	__pad[sizeof(struct sockaddr) -
+			      sizeof(__kernel_sa_family_t) -
+			      sizeof(__be16) - sizeof(struct in_addr) -
+			      sizeof(__u32)];
+};
+
+/*****************************************************************************
+ *  NETLINK_GENERIC netlink family.
+ *****************************************************************************/
+
+/*
+ * Commands.
+ * Valid TLVs of each command are:-
+ * TUNNEL_CREATE	- CONN_ID, pw_type, netns, ifname, ipinfo, udpinfo, udpcsum, vlanid
+ * TUNNEL_DELETE	- CONN_ID
+ * TUNNEL_MODIFY	- CONN_ID, udpcsum
+ * TUNNEL_GETSTATS	- CONN_ID, (stats)
+ * TUNNEL_GET		- CONN_ID, (...)
+ * SESSION_CREATE	- SESSION_ID, PW_TYPE, offset, data_seq, cookie, peer_cookie, offset, l2spec
+ * SESSION_DELETE	- SESSION_ID
+ * SESSION_MODIFY	- SESSION_ID, data_seq
+ * SESSION_GET		- SESSION_ID, (...)
+ * SESSION_GETSTATS	- SESSION_ID, (stats)
+ *
+ */
+enum {
+	L2TP_CMD_NOOP,
+	L2TP_CMD_TUNNEL_CREATE,
+	L2TP_CMD_TUNNEL_DELETE,
+	L2TP_CMD_TUNNEL_MODIFY,
+	L2TP_CMD_TUNNEL_GET,
+	L2TP_CMD_SESSION_CREATE,
+	L2TP_CMD_SESSION_DELETE,
+	L2TP_CMD_SESSION_MODIFY,
+	L2TP_CMD_SESSION_GET,
+	__L2TP_CMD_MAX,
+};
+
+#define L2TP_CMD_MAX			(__L2TP_CMD_MAX - 1)
+
+/*
+ * ATTR types defined for L2TP
+ */
+enum {
+	L2TP_ATTR_NONE,			/* no data */
+	L2TP_ATTR_PW_TYPE,		/* u16, enum l2tp_pwtype */
+	L2TP_ATTR_ENCAP_TYPE,		/* u16, enum l2tp_encap_type */
+	L2TP_ATTR_OFFSET,		/* u16 */
+	L2TP_ATTR_DATA_SEQ,		/* u16 */
+	L2TP_ATTR_L2SPEC_TYPE,		/* u8, enum l2tp_l2spec_type */
+	L2TP_ATTR_L2SPEC_LEN,		/* u8, enum l2tp_l2spec_type */
+	L2TP_ATTR_PROTO_VERSION,	/* u8 */
+	L2TP_ATTR_IFNAME,		/* string */
+	L2TP_ATTR_CONN_ID,		/* u32 */
+	L2TP_ATTR_PEER_CONN_ID,		/* u32 */
+	L2TP_ATTR_SESSION_ID,		/* u32 */
+	L2TP_ATTR_PEER_SESSION_ID,	/* u32 */
+	L2TP_ATTR_UDP_CSUM,		/* u8 */
+	L2TP_ATTR_VLAN_ID,		/* u16 */
+	L2TP_ATTR_COOKIE,		/* 0, 4 or 8 bytes */
+	L2TP_ATTR_PEER_COOKIE,		/* 0, 4 or 8 bytes */
+	L2TP_ATTR_DEBUG,		/* u32 */
+	L2TP_ATTR_RECV_SEQ,		/* u8 */
+	L2TP_ATTR_SEND_SEQ,		/* u8 */
+	L2TP_ATTR_LNS_MODE,		/* u8 */
+	L2TP_ATTR_USING_IPSEC,		/* u8 */
+	L2TP_ATTR_RECV_TIMEOUT,		/* msec */
+	L2TP_ATTR_FD,			/* int */
+	L2TP_ATTR_IP_SADDR,		/* u32 */
+	L2TP_ATTR_IP_DADDR,		/* u32 */
+	L2TP_ATTR_UDP_SPORT,		/* u16 */
+	L2TP_ATTR_UDP_DPORT,		/* u16 */
+	L2TP_ATTR_MTU,			/* u16 */
+	L2TP_ATTR_MRU,			/* u16 */
+	L2TP_ATTR_STATS,		/* nested */
+	__L2TP_ATTR_MAX,
+};
+
+#define L2TP_ATTR_MAX			(__L2TP_ATTR_MAX - 1)
+
+/* Nested in L2TP_ATTR_STATS */
+enum {
+	L2TP_ATTR_STATS_NONE,		/* no data */
+	L2TP_ATTR_TX_PACKETS,		/* u64 */
+	L2TP_ATTR_TX_BYTES,		/* u64 */
+	L2TP_ATTR_TX_ERRORS,		/* u64 */
+	L2TP_ATTR_RX_PACKETS,		/* u64 */
+	L2TP_ATTR_RX_BYTES,		/* u64 */
+	L2TP_ATTR_RX_SEQ_DISCARDS,	/* u64 */
+	L2TP_ATTR_RX_OOS_PACKETS,	/* u64 */
+	L2TP_ATTR_RX_ERRORS,		/* u64 */
+	__L2TP_ATTR_STATS_MAX,
+};
+
+#define L2TP_ATTR_STATS_MAX		(__L2TP_ATTR_STATS_MAX - 1)
+
+enum l2tp_pwtype {
+	L2TP_PWTYPE_NONE = 0x0000,
+	L2TP_PWTYPE_ETH_VLAN = 0x0004,
+	L2TP_PWTYPE_ETH = 0x0005,
+	L2TP_PWTYPE_PPP = 0x0007,
+	L2TP_PWTYPE_PPP_AC = 0x0008,
+	L2TP_PWTYPE_IP = 0x000b,
+	__L2TP_PWTYPE_MAX
+};
+
+enum l2tp_l2spec_type {
+	L2TP_L2SPECTYPE_NONE,
+	L2TP_L2SPECTYPE_DEFAULT,
+};
+
+enum l2tp_encap_type {
+	L2TP_ENCAPTYPE_UDP,
+	L2TP_ENCAPTYPE_IP,
+};
+
+enum l2tp_seqmode {
+	L2TP_SEQ_NONE = 0,
+	L2TP_SEQ_IP = 1,
+	L2TP_SEQ_ALL = 2,
+};
+
+/*
+ * NETLINK_GENERIC related info
+ */
+#define L2TP_GENL_NAME		"l2tp"
+#define L2TP_GENL_VERSION	0x1
+
+#endif

ip/Makefile

@@ -3,7 +3,7 @@ IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
     ipmaddr.o ipmonitor.o ipmroute.o ipprefix.o iptuntap.o \
     ipxfrm.o xfrm_state.o xfrm_policy.o xfrm_monitor.o \
     iplink_vlan.o link_veth.o link_gre.o iplink_can.o \
-    iplink_macvlan.o iplink_macvtap.o
+    iplink_macvlan.o iplink_macvtap.o ipl2tp.o
 
 RTMONOBJ=rtmon.o
 

ip/ip.c

@@ -45,7 +45,7 @@ static void usage(void)
 "       ip [ -force ] -batch filename\n"
 "where  OBJECT := { link | addr | addrlabel | route | rule | neigh | ntable |\n"
 "                   tunnel | tuntap | maddr | mroute | mrule | monitor | xfrm |\n"
-"                   netns }\n"
+"                   netns | l2tp }\n"
 "       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |\n"
 "                    -f[amily] { inet | inet6 | ipx | dnet | link } |\n"
 "                    -l[oops] { maximum-addr-flush-attempts } |\n"
@@ -72,6 +72,7 @@ static const struct cmd {
 	{ "neighbour",	do_ipneigh },
 	{ "ntable",	do_ipntable },
 	{ "ntbl",	do_ipntable },
+	{ "l2tp",	do_ipl2tp },
 	{ "link",	do_iplink },
 	{ "tunnel",	do_iptunnel },
 	{ "tunl",	do_iptunnel },

ip/ip_common.h

@@ -40,6 +40,7 @@ extern int do_multiroute(int argc, char **argv);
 extern int do_multirule(int argc, char **argv);
 extern int do_netns(int argc, char **argv);
 extern int do_xfrm(int argc, char **argv);
+extern int do_ipl2tp(int argc, char **argv);
 
 static inline int rtm_get_table(struct rtmsg *r, struct rtattr **tb)
 {