kernel-ark/net/ipv6/ila.c
Tom Herbert 92b78aff85 ila: Precompute checksum difference for translations
In the ILA build state for LWT compute the checksum difference to apply
to transport checksums that include the IPv6 pseudo header. The
difference is between the route destination (from fib6_config) and the
locator to write.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-24 10:34:40 -07:00

230 lines
5.2 KiB
C

#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");