368 lines
8.3 KiB
C
368 lines
8.3 KiB
C
|
/*
|
||
|
|
* GRE over IPv4 demultiplexer driver
|
||
|
|
*
|
||
|
|
* Authors: Dmitry Kozlov (xeb@mail.ru)
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License
|
||
|
|
* as published by the Free Software Foundation; either version
|
||
|
|
* 2 of the License, or (at your option) any later version.
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
||
|
|
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/if.h>
|
||
|
|
#include <linux/icmp.h>
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/kmod.h>
|
||
|
|
#include <linux/skbuff.h>
|
||
|
|
#include <linux/in.h>
|
||
|
|
#include <linux/ip.h>
|
||
|
|
#include <linux/netdevice.h>
|
||
|
|
#include <linux/if_tunnel.h>
|
||
|
|
#include <linux/spinlock.h>
|
||
|
|
#include <net/protocol.h>
|
||
|
|
#include <net/gre.h>
|
||
|
|
|
||
|
|
#include <net/icmp.h>
|
||
|
|
#include <net/route.h>
|
||
|
|
#include <net/xfrm.h>
|
||
|
|
|
||
|
|
static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
|
||
|
|
static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX];
|
||
|
|
|
||
|
|
int gre_add_protocol(const struct gre_protocol *proto, u8 version)
|
||
|
|
{
|
||
|
|
if (version >= GREPROTO_MAX)
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
|
||
|
|
0 : -EBUSY;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(gre_add_protocol);
|
||
|
|
|
||
|
|
int gre_del_protocol(const struct gre_protocol *proto, u8 version)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
if (version >= GREPROTO_MAX)
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
|
||
|
|
0 : -EBUSY;
|
||
|
|
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
synchronize_rcu();
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(gre_del_protocol);
|
||
|
|
|
||
|
|
void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
|
||
|
|
int hdr_len)
|
||
|
|
{
|
||
|
|
struct gre_base_hdr *greh;
|
||
|
|
|
||
|
|
skb_push(skb, hdr_len);
|
||
|
|
|
||
|
|
skb_reset_transport_header(skb);
|
||
|
|
greh = (struct gre_base_hdr *)skb->data;
|
||
|
|
greh->flags = tnl_flags_to_gre_flags(tpi->flags);
|
||
|
|
greh->protocol = tpi->proto;
|
||
|
|
|
||
|
|
if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) {
|
||
|
|
__be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
|
||
|
|
|
||
|
|
if (tpi->flags&TUNNEL_SEQ) {
|
||
|
|
*ptr = tpi->seq;
|
||
|
|
ptr--;
|
||
|
|
}
|
||
|
|
if (tpi->flags&TUNNEL_KEY) {
|
||
|
|
*ptr = tpi->key;
|
||
|
|
ptr--;
|
||
|
|
}
|
||
|
|
if (tpi->flags&TUNNEL_CSUM &&
|
||
|
|
!(skb_shinfo(skb)->gso_type &
|
||
|
|
(SKB_GSO_GRE|SKB_GSO_GRE_CSUM))) {
|
||
|
|
*ptr = 0;
|
||
|
|
*(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
|
||
|
|
skb->len, 0));
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(gre_build_header);
|
||
|
|
|
||
|
|
static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
|
||
|
|
bool *csum_err)
|
||
|
|
{
|
||
|
|
const struct gre_base_hdr *greh;
|
||
|
|
__be32 *options;
|
||
|
|
int hdr_len;
|
||
|
|
|
||
|
|
if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
greh = (struct gre_base_hdr *)skb_transport_header(skb);
|
||
|
|
if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
tpi->flags = gre_flags_to_tnl_flags(greh->flags);
|
||
|
|
hdr_len = ip_gre_calc_hlen(tpi->flags);
|
||
|
|
|
||
|
|
if (!pskb_may_pull(skb, hdr_len))
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
greh = (struct gre_base_hdr *)skb_transport_header(skb);
|
||
|
|
tpi->proto = greh->protocol;
|
||
|
|
|
||
|
|
options = (__be32 *)(greh + 1);
|
||
|
|
if (greh->flags & GRE_CSUM) {
|
||
|
|
if (skb_checksum_simple_validate(skb)) {
|
||
|
|
*csum_err = true;
|
||
|
|
return -EINVAL;
|
||
|
|
}
|
||
|
|
|
||
|
|
skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
|
||
|
|
null_compute_pseudo);
|
||
|
|
|
||
|
|
options++;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (greh->flags & GRE_KEY) {
|
||
|
|
tpi->key = *options;
|
||
|
|
options++;
|
||
|
|
} else
|
||
|
|
tpi->key = 0;
|
||
|
|
|
||
|
|
if (unlikely(greh->flags & GRE_SEQ)) {
|
||
|
|
tpi->seq = *options;
|
||
|
|
options++;
|
||
|
|
} else
|
||
|
|
tpi->seq = 0;
|
||
|
|
|
||
|
|
/* WCCP version 1 and 2 protocol decoding.
|
||
|
|
* - Change protocol to IP
|
||
|
|
* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
|
||
|
|
*/
|
||
|
|
if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
|
||
|
|
tpi->proto = htons(ETH_P_IP);
|
||
|
|
if ((*(u8 *)options & 0xF0) != 0x40) {
|
||
|
|
hdr_len += 4;
|
||
|
|
if (!pskb_may_pull(skb, hdr_len))
|
||
|
|
return -EINVAL;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return iptunnel_pull_header(skb, hdr_len, tpi->proto);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int gre_cisco_rcv(struct sk_buff *skb)
|
||
|
|
{
|
||
|
|
struct tnl_ptk_info tpi;
|
||
|
|
int i;
|
||
|
|
bool csum_err = false;
|
||
|
|
|
||
|
|
#ifdef CONFIG_NET_IPGRE_BROADCAST
|
||
|
|
if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
|
||
|
|
/* Looped back packet, drop it! */
|
||
|
|
if (rt_is_output_route(skb_rtable(skb)))
|
||
|
|
goto drop;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
if (parse_gre_header(skb, &tpi, &csum_err) < 0)
|
||
|
|
goto drop;
|
||
|
|
|
||
|
|
rcu_read_lock();
|
||
|
|
for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
|
||
|
|
struct gre_cisco_protocol *proto;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
proto = rcu_dereference(gre_cisco_proto_list[i]);
|
||
|
|
if (!proto)
|
||
|
|
continue;
|
||
|
|
ret = proto->handler(skb, &tpi);
|
||
|
|
if (ret == PACKET_RCVD) {
|
||
|
|
rcu_read_unlock();
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
rcu_read_unlock();
|
||
|
|
|
||
|
|
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
|
||
|
|
drop:
|
||
|
|
kfree_skb(skb);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void gre_cisco_err(struct sk_buff *skb, u32 info)
|
||
|
|
{
|
||
|
|
/* All the routers (except for Linux) return only
|
||
|
|
* 8 bytes of packet payload. It means, that precise relaying of
|
||
|
|
* ICMP in the real Internet is absolutely infeasible.
|
||
|
|
*
|
||
|
|
* Moreover, Cisco "wise men" put GRE key to the third word
|
||
|
|
* in GRE header. It makes impossible maintaining even soft
|
||
|
|
* state for keyed
|
||
|
|
* GRE tunnels with enabled checksum. Tell them "thank you".
|
||
|
|
*
|
||
|
|
* Well, I wonder, rfc1812 was written by Cisco employee,
|
||
|
|
* what the hell these idiots break standards established
|
||
|
|
* by themselves???
|
||
|
|
*/
|
||
|
|
|
||
|
|
const int type = icmp_hdr(skb)->type;
|
||
|
|
const int code = icmp_hdr(skb)->code;
|
||
|
|
struct tnl_ptk_info tpi;
|
||
|
|
bool csum_err = false;
|
||
|
|
int i;
|
||
|
|
|
||
|
|
if (parse_gre_header(skb, &tpi, &csum_err)) {
|
||
|
|
if (!csum_err) /* ignore csum errors. */
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
|
||
|
|
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
|
||
|
|
skb->dev->ifindex, 0, IPPROTO_GRE, 0);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (type == ICMP_REDIRECT) {
|
||
|
|
ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
|
||
|
|
IPPROTO_GRE, 0);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
rcu_read_lock();
|
||
|
|
for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
|
||
|
|
struct gre_cisco_protocol *proto;
|
||
|
|
|
||
|
|
proto = rcu_dereference(gre_cisco_proto_list[i]);
|
||
|
|
if (!proto)
|
||
|
|
continue;
|
||
|
|
|
||
|
|
if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
}
|
||
|
|
out:
|
||
|
|
rcu_read_unlock();
|
||
|
|
}
|
||
|
|
|
||
|
|
static int gre_rcv(struct sk_buff *skb)
|
||
|
|
{
|
||
|
|
const struct gre_protocol *proto;
|
||
|
|
u8 ver;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
if (!pskb_may_pull(skb, 12))
|
||
|
|
goto drop;
|
||
|
|
|
||
|
|
ver = skb->data[1]&0x7f;
|
||
|
|
if (ver >= GREPROTO_MAX)
|
||
|
|
goto drop;
|
||
|
|
|
||
|
|
rcu_read_lock();
|
||
|
|
proto = rcu_dereference(gre_proto[ver]);
|
||
|
|
if (!proto || !proto->handler)
|
||
|
|
goto drop_unlock;
|
||
|
|
ret = proto->handler(skb);
|
||
|
|
rcu_read_unlock();
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
drop_unlock:
|
||
|
|
rcu_read_unlock();
|
||
|
|
drop:
|
||
|
|
kfree_skb(skb);
|
||
|
|
return NET_RX_DROP;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void gre_err(struct sk_buff *skb, u32 info)
|
||
|
|
{
|
||
|
|
const struct gre_protocol *proto;
|
||
|
|
const struct iphdr *iph = (const struct iphdr *)skb->data;
|
||
|
|
u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
|
||
|
|
|
||
|
|
if (ver >= GREPROTO_MAX)
|
||
|
|
return;
|
||
|
|
|
||
|
|
rcu_read_lock();
|
||
|
|
proto = rcu_dereference(gre_proto[ver]);
|
||
|
|
if (proto && proto->err_handler)
|
||
|
|
proto->err_handler(skb, info);
|
||
|
|
rcu_read_unlock();
|
||
|
|
}
|
||
|
|
|
||
|
|
static const struct net_protocol net_gre_protocol = {
|
||
|
|
.handler = gre_rcv,
|
||
|
|
.err_handler = gre_err,
|
||
|
|
.netns_ok = 1,
|
||
|
|
};
|
||
|
|
|
||
|
|
static const struct gre_protocol ipgre_protocol = {
|
||
|
|
.handler = gre_cisco_rcv,
|
||
|
|
.err_handler = gre_cisco_err,
|
||
|
|
};
|
||
|
|
|
||
|
|
int gre_cisco_register(struct gre_cisco_protocol *newp)
|
||
|
|
{
|
||
|
|
struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
|
||
|
|
&gre_cisco_proto_list[newp->priority];
|
||
|
|
|
||
|
|
return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(gre_cisco_register);
|
||
|
|
|
||
|
|
int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
|
||
|
|
{
|
||
|
|
struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
|
||
|
|
&gre_cisco_proto_list[del_proto->priority];
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;
|
||
|
|
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
synchronize_net();
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(gre_cisco_unregister);
|
||
|
|
|
||
|
|
static int __init gre_init(void)
|
||
|
|
{
|
||
|
|
pr_info("GRE over IPv4 demultiplexor driver\n");
|
||
|
|
|
||
|
|
if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
|
||
|
|
pr_err("can't add protocol\n");
|
||
|
|
goto err;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
|
||
|
|
pr_info("%s: can't add ipgre handler\n", __func__);
|
||
|
|
goto err_gre;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
err_gre:
|
||
|
|
inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
|
||
|
|
err:
|
||
|
|
return -EAGAIN;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void __exit gre_exit(void)
|
||
|
|
{
|
||
|
|
gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
|
||
|
|
inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
|
||
|
|
}
|
||
|
|
|
||
|
|
module_init(gre_init);
|
||
|
|
module_exit(gre_exit);
|
||
|
|
|
||
|
|
MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
|
||
|
|
MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
|
||
|
|
MODULE_LICENSE("GPL");
|