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#include <linux/errno.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/types.h>
#include <net/checksum.h>
#include <net/ip.h>
#include <net/ip6_fib.h>
#include <net/lwtunnel.h>
#include <net/protocol.h>
#include <uapi/linux/ila.h>
struct ila_params {
__be64 locator;
__be64 locator_match;
__wsum csum_diff;
};
static inline struct ila_params *ila_params_lwtunnel(
struct lwtunnel_state *lwstate)
{
return (struct ila_params *)lwstate->data;
}
static inline __wsum compute_csum_diff8(const __be32 *from, const __be32 *to)
{
__be32 diff[] = {
~from[0], ~from[1], to[0], to[1],
};
return csum_partial(diff, sizeof(diff), 0);
}
static inline __wsum get_csum_diff(struct ipv6hdr *ip6h, struct ila_params *p)
{
if (*(__be64 *)&ip6h->daddr == p->locator_match)
return p->csum_diff;
else
return compute_csum_diff8((__be32 *)&ip6h->daddr,
(__be32 *)&p->locator);
}
static void update_ipv6_locator(struct sk_buff *skb, struct ila_params *p)
{
__wsum diff;
struct ipv6hdr *ip6h = ipv6_hdr(skb);
size_t nhoff = sizeof(struct ipv6hdr);
/* First update checksum */
switch (ip6h->nexthdr) {
case NEXTHDR_TCP:
if (likely(pskb_may_pull(skb, nhoff + sizeof(struct tcphdr)))) {
struct tcphdr *th = (struct tcphdr *)
(skb_network_header(skb) + nhoff);
diff = get_csum_diff(ip6h, p);
inet_proto_csum_replace_by_diff(&th->check, skb,
diff, true);
}
break;
case NEXTHDR_UDP:
if (likely(pskb_may_pull(skb, nhoff + sizeof(struct udphdr)))) {
struct udphdr *uh = (struct udphdr *)
(skb_network_header(skb) + nhoff);
if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
diff = get_csum_diff(ip6h, p);
inet_proto_csum_replace_by_diff(&uh->check, skb,
diff, true);
if (!uh->check)
uh->check = CSUM_MANGLED_0;
}
}
break;
case NEXTHDR_ICMP:
if (likely(pskb_may_pull(skb,
nhoff + sizeof(struct icmp6hdr)))) {
struct icmp6hdr *ih = (struct icmp6hdr *)
(skb_network_header(skb) + nhoff);
diff = get_csum_diff(ip6h, p);
inet_proto_csum_replace_by_diff(&ih->icmp6_cksum, skb,
diff, true);
}
break;
}
/* Now change destination address */
*(__be64 *)&ip6h->daddr = p->locator;
}
static int ila_output(struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
if (skb->protocol != htons(ETH_P_IPV6))
goto drop;
update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
return dst->lwtstate->orig_output(sk, skb);
drop:
kfree_skb(skb);
return -EINVAL;
}
static int ila_input(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
if (skb->protocol != htons(ETH_P_IPV6))
goto drop;
update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
return dst->lwtstate->orig_input(skb);
drop:
kfree_skb(skb);
return -EINVAL;
}
static struct nla_policy ila_nl_policy[ILA_ATTR_MAX + 1] = {
[ILA_ATTR_LOCATOR] = { .type = NLA_U64, },
};
static int ila_build_state(struct net_device *dev, struct nlattr *nla,
unsigned int family, const void *cfg,
struct lwtunnel_state **ts)
{
struct ila_params *p;
struct nlattr *tb[ILA_ATTR_MAX + 1];
size_t encap_len = sizeof(*p);
struct lwtunnel_state *newts;
const struct fib6_config *cfg6 = cfg;
int ret;
if (family != AF_INET6)
return -EINVAL;
ret = nla_parse_nested(tb, ILA_ATTR_MAX, nla,
ila_nl_policy);
if (ret < 0)
return ret;
if (!tb[ILA_ATTR_LOCATOR])
return -EINVAL;
newts = lwtunnel_state_alloc(encap_len);
if (!newts)
return -ENOMEM;
newts->len = encap_len;
p = ila_params_lwtunnel(newts);
p->locator = (__force __be64)nla_get_u64(tb[ILA_ATTR_LOCATOR]);
if (cfg6->fc_dst_len > sizeof(__be64)) {
/* Precompute checksum difference for translation since we
* know both the old locator and the new one.
*/
p->locator_match = *(__be64 *)&cfg6->fc_dst;
p->csum_diff = compute_csum_diff8(
(__be32 *)&p->locator_match, (__be32 *)&p->locator);
}
newts->type = LWTUNNEL_ENCAP_ILA;
newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
LWTUNNEL_STATE_INPUT_REDIRECT;
*ts = newts;
return 0;
}
static int ila_fill_encap_info(struct sk_buff *skb,
struct lwtunnel_state *lwtstate)
{
struct ila_params *p = ila_params_lwtunnel(lwtstate);
if (nla_put_u64(skb, ILA_ATTR_LOCATOR, (__force u64)p->locator))
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
static int ila_encap_nlsize(struct lwtunnel_state *lwtstate)
{
/* No encapsulation overhead */
return 0;
}
static int ila_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
struct ila_params *a_p = ila_params_lwtunnel(a);
struct ila_params *b_p = ila_params_lwtunnel(b);
return (a_p->locator != b_p->locator);
}
static const struct lwtunnel_encap_ops ila_encap_ops = {
.build_state = ila_build_state,
.output = ila_output,
.input = ila_input,
.fill_encap = ila_fill_encap_info,
.get_encap_size = ila_encap_nlsize,
.cmp_encap = ila_encap_cmp,
};
static int __init ila_init(void)
{
return lwtunnel_encap_add_ops(&ila_encap_ops, LWTUNNEL_ENCAP_ILA);
}
static void __exit ila_fini(void)
{
lwtunnel_encap_del_ops(&ila_encap_ops, LWTUNNEL_ENCAP_ILA);
}
module_init(ila_init);
module_exit(ila_fini);
MODULE_AUTHOR("Tom Herbert <tom@herbertland.com>");
MODULE_LICENSE("GPL");
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