[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>
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@ -42,6 +42,7 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
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/* UDP encapsulation types */
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#define UDP_ENCAP_ESPINUDP_NON_IKE 1 /* draft-ietf-ipsec-nat-t-ike-00/01 */
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#define UDP_ENCAP_ESPINUDP 2 /* draft-ietf-ipsec-udp-encaps-06 */
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#define UDP_ENCAP_L2TPINUDP 3 /* rfc2661 */
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#ifdef __KERNEL__
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#include <linux/types.h>
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@ -70,6 +71,11 @@ struct udp_sock {
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#define UDPLITE_SEND_CC 0x2 /* set via udplite setsockopt */
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#define UDPLITE_RECV_CC 0x4 /* set via udplite setsocktopt */
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__u8 pcflag; /* marks socket as UDP-Lite if > 0 */
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__u8 unused[3];
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/*
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* For encapsulation sockets.
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*/
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int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
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};
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static inline struct udp_sock *udp_sk(const struct sock *sk)
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@ -70,6 +70,7 @@
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* Alexey Kuznetsov: allow both IPv4 and IPv6 sockets to bind
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* a single port at the same time.
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* Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
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* James Chapman : Add L2TP encapsulation type.
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*
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*
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* This program is free software; you can redistribute it and/or
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@ -923,12 +924,10 @@ int udp_disconnect(struct sock *sk, int flags)
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* 1 if the UDP system should process it
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* 0 if we should drop this packet
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* -1 if it should get processed by xfrm4_rcv_encap
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* -2 if it should get processed by l2tp
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*/
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static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
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{
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#ifndef CONFIG_XFRM
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return 1;
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#else
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struct udp_sock *up = udp_sk(sk);
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struct udphdr *uh;
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struct iphdr *iph;
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@ -983,8 +982,14 @@ static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
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/* Must be an IKE packet.. pass it through */
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return 1;
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break;
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case UDP_ENCAP_L2TPINUDP:
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/* Let caller know to send this to l2tp */
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return -2;
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}
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#ifndef CONFIG_XFRM
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return 1;
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#else
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/* At this point we are sure that this is an ESPinUDP packet,
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* so we need to remove 'len' bytes from the packet (the UDP
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* header and optional ESP marker bytes) and then modify the
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@ -1055,12 +1060,25 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
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kfree_skb(skb);
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return 0;
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}
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if (ret < 0) {
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if (ret == -1) {
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/* process the ESP packet */
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ret = xfrm4_rcv_encap(skb, up->encap_type);
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UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
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return -ret;
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}
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if (ret == -2) {
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/* process the L2TP packet */
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if (up->encap_rcv != NULL) {
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ret = (*up->encap_rcv)(sk, skb);
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if (ret <= 0) {
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UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
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return ret;
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}
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/* FALLTHROUGH -- pass up as UDP packet */
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}
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}
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/* FALLTHROUGH -- it's a UDP Packet */
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}
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@ -1349,6 +1367,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
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case 0:
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case UDP_ENCAP_ESPINUDP:
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case UDP_ENCAP_ESPINUDP_NON_IKE:
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case UDP_ENCAP_L2TPINUDP:
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up->encap_type = val;
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break;
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default:
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