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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/icmpv6.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <net/fou.h>
#include <net/ip.h>
#include <net/ip6_tunnel.h>
#include <net/ip6_checksum.h>
#include <net/protocol.h>
#include <net/udp.h>
#include <net/udp_tunnel.h>
#if IS_ENABLED(CONFIG_IPV6_FOU_TUNNEL)
static void fou6_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,
struct flowi6 *fl6, u8 *protocol, __be16 sport)
{
struct udphdr *uh;
skb_push(skb, sizeof(struct udphdr));
skb_reset_transport_header(skb);
uh = udp_hdr(skb);
uh->dest = e->dport;
uh->source = sport;
uh->len = htons(skb->len);
udp6_set_csum(!(e->flags & TUNNEL_ENCAP_FLAG_CSUM6), skb,
&fl6->saddr, &fl6->daddr, skb->len);
*protocol = IPPROTO_UDP;
}
static int fou6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
u8 *protocol, struct flowi6 *fl6)
{
__be16 sport;
int err;
int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
err = __fou_build_header(skb, e, protocol, &sport, type);
if (err)
return err;
fou6_build_udp(skb, e, fl6, protocol, sport);
return 0;
}
static int gue6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
u8 *protocol, struct flowi6 *fl6)
{
__be16 sport;
int err;
int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
err = __gue_build_header(skb, e, protocol, &sport, type);
if (err)
return err;
fou6_build_udp(skb, e, fl6, protocol, sport);
return 0;
}
static int gue6_err_proto_handler(int proto, struct sk_buff *skb,
struct inet6_skb_parm *opt,
u8 type, u8 code, int offset, __be32 info)
{
const struct inet6_protocol *ipprot;
ipprot = rcu_dereference(inet6_protos[proto]);
if (ipprot && ipprot->err_handler) {
if (!ipprot->err_handler(skb, opt, type, code, offset, info))
return 0;
}
return -ENOENT;
}
static int gue6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
u8 type, u8 code, int offset, __be32 info)
{
int transport_offset = skb_transport_offset(skb);
struct guehdr *guehdr;
size_t len, optlen;
int ret;
len = sizeof(struct udphdr) + sizeof(struct guehdr);
if (!pskb_may_pull(skb, transport_offset + len))
return -EINVAL;
guehdr = (struct guehdr *)&udp_hdr(skb)[1];
switch (guehdr->version) {
case 0: /* Full GUE header present */
break;
case 1: {
/* Direct encasulation of IPv4 or IPv6 */
skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
switch (((struct iphdr *)guehdr)->version) {
case 4:
ret = gue6_err_proto_handler(IPPROTO_IPIP, skb, opt,
type, code, offset, info);
goto out;
case 6:
ret = gue6_err_proto_handler(IPPROTO_IPV6, skb, opt,
type, code, offset, info);
goto out;
default:
ret = -EOPNOTSUPP;
goto out;
}
}
default: /* Undefined version */
return -EOPNOTSUPP;
}
if (guehdr->control)
return -ENOENT;
optlen = guehdr->hlen << 2;
if (!pskb_may_pull(skb, transport_offset + len + optlen))
return -EINVAL;
guehdr = (struct guehdr *)&udp_hdr(skb)[1];
if (validate_gue_flags(guehdr, optlen))
return -EINVAL;
/* Handling exceptions for direct UDP encapsulation in GUE would lead to
* recursion. Besides, this kind of encapsulation can't even be
* configured currently. Discard this.
*/
if (guehdr->proto_ctype == IPPROTO_UDP ||
guehdr->proto_ctype == IPPROTO_UDPLITE)
return -EOPNOTSUPP;
skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
ret = gue6_err_proto_handler(guehdr->proto_ctype, skb,
opt, type, code, offset, info);
out:
skb_set_transport_header(skb, transport_offset);
return ret;
}
static const struct ip6_tnl_encap_ops fou_ip6tun_ops = {
.encap_hlen = fou_encap_hlen,
.build_header = fou6_build_header,
.err_handler = gue6_err,
};
static const struct ip6_tnl_encap_ops gue_ip6tun_ops = {
.encap_hlen = gue_encap_hlen,
.build_header = gue6_build_header,
.err_handler = gue6_err,
};
static int ip6_tnl_encap_add_fou_ops(void)
{
int ret;
ret = ip6_tnl_encap_add_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
if (ret < 0) {
pr_err("can't add fou6 ops\n");
return ret;
}
ret = ip6_tnl_encap_add_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
if (ret < 0) {
pr_err("can't add gue6 ops\n");
ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
return ret;
}
return 0;
}
static void ip6_tnl_encap_del_fou_ops(void)
{
ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
ip6_tnl_encap_del_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
}
#else
static int ip6_tnl_encap_add_fou_ops(void)
{
return 0;
}
static void ip6_tnl_encap_del_fou_ops(void)
{
}
#endif
static int __init fou6_init(void)
{
int ret;
ret = ip6_tnl_encap_add_fou_ops();
return ret;
}
static void __exit fou6_fini(void)
{
ip6_tnl_encap_del_fou_ops();
}
module_init(fou6_init);
module_exit(fou6_fini);
MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
MODULE_LICENSE("GPL");
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