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Commit 342f0234 authored by James Chapman's avatar James Chapman Committed by David S. Miller
Browse files

[UDP]: Introduce UDP encapsulation type for L2TP 



This patch adds a new UDP_ENCAP_L2TPINUDP encapsulation type for UDP
sockets. When a UDP socket's encap_type is UDP_ENCAP_L2TPINUDP, the
skb is delivered to a function pointed to by the udp_sock's
encap_rcv funcptr. If the skb isn't wanted by L2TP, it returns >0, which
causes it to be passed through to UDP.

Include padding to put the new encap_rcv field on a 4-byte boundary.

Previously, the only user of UDP encap sockets was ESP, so when
CONFIG_XFRM was not defined, some of the encap code was compiled
out. This patch changes that. As a result, udp_encap_rcv() will
now do a little more work when CONFIG_XFRM is not defined.

Signed-off-by: default avatarJames Chapman <jchapman@katalix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4417da66

include/linux/udp.h

+6 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb) 
/* UDP encapsulation types */

#define UDP_ENCAP_ESPINUDP_NON_IKE	1 /* draft-ietf-ipsec-nat-t-ike-00/01 */

#define UDP_ENCAP_ESPINUDP	2 /* draft-ietf-ipsec-udp-encaps-06 */

#define UDP_ENCAP_L2TPINUDP	3 /* rfc2661 */



#ifdef __KERNEL__

#include <linux/types.h>
@@ -70,6 +71,11 @@ struct udp_sock { 
#define UDPLITE_SEND_CC  0x2  		/* set via udplite setsockopt         */

#define UDPLITE_RECV_CC  0x4		/* set via udplite setsocktopt        */

	__u8		 pcflag;        /* marks socket as UDP-Lite if > 0    */

	__u8		 unused[3];

	/*

	 * For encapsulation sockets.

	 */

	int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);

};



static inline struct udp_sock *udp_sk(const struct sock *sk)

net/ipv4/udp.c

+23 −4
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ 
 *	Alexey Kuznetsov:		allow both IPv4 and IPv6 sockets to bind

 *					a single port at the same time.

 *	Derek Atkins <derek@ihtfp.com>: Add Encapulation Support

 *	James Chapman		:	Add L2TP encapsulation type.

 *

 *

 *		This program is free software; you can redistribute it and/or
@@ -923,12 +924,10 @@ int udp_disconnect(struct sock *sk, int flags) 
 * 	1  if the UDP system should process it

 *	0  if we should drop this packet

 * 	-1 if it should get processed by xfrm4_rcv_encap

 *	-2 if it should get processed by l2tp

 */

static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)

{

#ifndef CONFIG_XFRM

	return 1;

#else

	struct udp_sock *up = udp_sk(sk);

	struct udphdr *uh;

	struct iphdr *iph;
@@ -983,8 +982,14 @@ static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb) 
			/* Must be an IKE packet.. pass it through */

			return 1;

		break;

	case UDP_ENCAP_L2TPINUDP:

		/* Let caller know to send this to l2tp */

		return -2;

	}



#ifndef CONFIG_XFRM

	return 1;

#else

	/* At this point we are sure that this is an ESPinUDP packet,

	 * so we need to remove 'len' bytes from the packet (the UDP

	 * header and optional ESP marker bytes) and then modify the
@@ -1055,12 +1060,25 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb) 
			kfree_skb(skb);

			return 0;

		}

		if (ret < 0) {

		if (ret == -1) {

			/* process the ESP packet */

			ret = xfrm4_rcv_encap(skb, up->encap_type);

			UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);

			return -ret;

		}

		if (ret == -2) {

			/* process the L2TP packet */

			if (up->encap_rcv != NULL) {

				ret = (*up->encap_rcv)(sk, skb);

				if (ret <= 0) {

					UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);

					return ret;

				}



				/* FALLTHROUGH -- pass up as UDP packet */

			}

		}



		/* FALLTHROUGH -- it's a UDP Packet */

	}
@@ -1349,6 +1367,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname, 
		case 0:

		case UDP_ENCAP_ESPINUDP:

		case UDP_ENCAP_ESPINUDP_NON_IKE:

		case UDP_ENCAP_L2TPINUDP:

			up->encap_type = val;

			break;

		default: