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linux/net/ipv6/fou6.c
Stefano Brivio b8a51b38e4 fou, fou6: ICMP error handlers for FoU and GUE
As the destination port in FoU and GUE receiving sockets doesn't
necessarily match the remote destination port, we can't associate errors
to the encapsulating tunnels with a socket lookup -- we need to blindly
try them instead. This means we don't even know if we are handling errors
for FoU or GUE without digging into the packets.

Hence, implement a single handler for both, one for IPv4 and one for IPv6,
that will check whether the packet that generated the ICMP error used a
direct IP encapsulation or if it had a GUE header, and send the error to
the matching protocol handler, if any.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-08 17:13:08 -08:00

213 lines
4.5 KiB
C

#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, u32 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 optlen;
int ret;
if (skb->len < sizeof(struct udphdr) + sizeof(struct guehdr))
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 (validate_gue_flags(guehdr, optlen))
return -EINVAL;
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");