[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: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index facb7e2..b9276f8 100644
--- a/net/ipv4/udp.c
+++ b/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@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 @@
* 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 @@
/* 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 @@
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 @@
case 0:
case UDP_ENCAP_ESPINUDP:
case UDP_ENCAP_ESPINUDP_NON_IKE:
+ case UDP_ENCAP_L2TPINUDP:
up->encap_type = val;
break;
default: