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Date: Mon, 30 Apr 2007 10:52:01 +0100
From: James Chapman <jchapman@...alix.com>
To: netdev@...r.kernel.org
Subject: [PATCH 1/5 2.6.21] 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 udp_encap_l2tp_rcv. If
the skb isn't wanted by L2TP, it returns >0, which causes it to be
passed through to UDP. A funcptr is used for udp_encap_l2tp_rcv to
allow L2TP to be implemented as a kernel module.
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@...alix.com>
---
There are some magic numbers returned by udp_encap_rcv() that
should perhaps now be made #defines. I chose not to do so in
this patch.
Index: linux-2.6.21/include/linux/udp.h
===================================================================
--- linux-2.6.21.orig/include/linux/udp.h
+++ linux-2.6.21/include/linux/udp.h
@@ -33,6 +33,7 @@ struct udphdr {
/* 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>
@@ -69,6 +70,8 @@ static inline struct udp_sock *udp_sk(co
}
#define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)
+extern int (*udp_encap_l2tp_rcv)(struct sock *sk, struct sk_buff *skb);
+
#endif
#endif /* _LINUX_UDP_H */
Index: linux-2.6.21/net/ipv4/udp.c
===================================================================
--- linux-2.6.21.orig/net/ipv4/udp.c
+++ linux-2.6.21/net/ipv4/udp.c
@@ -70,6 +70,7 @@
* Alexey Kuznetsov: allow both IPv4 and IPv6 sockets to bind
* a single port at the same time.
* Derek Atkins <derek@...fp.com>: Add Encapulation Support
+ * James Chapman : Add L2TP encapsulation type.
*
*
* This program is free software; you can redistribute it and/or
@@ -112,6 +113,12 @@ DEFINE_SNMP_STAT(struct udp_mib, udp_sta
struct hlist_head udp_hash[UDP_HTABLE_SIZE];
DEFINE_RWLOCK(udp_hash_lock);
+/* For use by L2TP protocol code (encap_type==UDP_ENCAP_L2TPINUDP).
+ * Using function pointers allows L2TP to be implemented as a
+ * module.
+ */
+int (*udp_encap_l2tp_rcv)(struct sock *sk, struct sk_buff *skb);
+
static int udp_port_rover;
static inline int __udp_lib_lport_inuse(__u16 num, struct hlist_head udptable[])
@@ -919,12 +926,10 @@ int udp_disconnect(struct sock *sk, int
* 1 if the 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;
@@ -979,8 +984,14 @@ static int udp_encap_rcv(struct sock * s
/* 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
@@ -1050,12 +1061,25 @@ int udp_queue_rcv_skb(struct sock * sk,
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 (udp_encap_l2tp_rcv != NULL) {
+ ret = (*udp_encap_l2tp_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 */
}
@@ -1336,6 +1360,7 @@ int udp_lib_setsockopt(struct sock *sk,
case 0:
case UDP_ENCAP_ESPINUDP:
case UDP_ENCAP_ESPINUDP_NON_IKE:
+ case UDP_ENCAP_L2TPINUDP:
up->encap_type = val;
break;
default:
@@ -1729,6 +1754,8 @@ EXPORT_SYMBOL(udp_lib_getsockopt);
EXPORT_SYMBOL(udp_lib_setsockopt);
EXPORT_SYMBOL(udp_poll);
+EXPORT_SYMBOL(udp_encap_l2tp_rcv);
+
#ifdef CONFIG_PROC_FS
EXPORT_SYMBOL(udp_proc_register);
EXPORT_SYMBOL(udp_proc_unregister);
-
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