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[UDP]: Introduce UDP encapsulation type for L2TP

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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: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2007-06-27 15:37:46 -07:00 committed by David S. Miller
parent 4417da668c
commit 342f0234c7
2 changed files with 29 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/udp.h
View file

@ -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)

27
net/ipv4/udp.c
View file

@ -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: