static int
sctp_snat_handler(struct sk_buff *skb,
struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
{
sctp_sctphdr_t *sctph;
unsigned int sctphoff;
struct sk_buff *iter;
__be32 crc32;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
sctphoff = sizeof(struct ipv6hdr);
else
#endif
sctphoff = ip_hdrlen(skb);
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, sctphoff + sizeof(*sctph)))
return 0;
if (unlikely(cp->app != NULL)) {
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
/* Call application helper if needed */
if (!ip_vs_app_pkt_out(cp, skb))
return 0;
}
sctph = (void *) skb_network_header(skb) + sctphoff;
sctph->source = cp->vport;
/* Calculate the checksum */
crc32 = sctp_start_cksum((u8 *) sctph, skb_headlen(skb) - sctphoff);
skb_walk_frags(skb, iter)
crc32 = sctp_update_cksum((u8 *) iter->data, skb_headlen(iter),
crc32);
crc32 = sctp_end_cksum(crc32);
sctph->checksum = crc32;
return 1;
}
static bool
sctp_manip_pkt(struct sk_buff *skb,
unsigned int iphdroff,
const struct nf_conntrack_tuple *tuple,
enum nf_nat_manip_type maniptype)
{
const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
sctp_sctphdr_t *hdr;
unsigned int hdroff = iphdroff + iph->ihl*4;
__be32 oldip, newip;
u32 crc32;
if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
return false;
iph = (struct iphdr *)(skb->data + iphdroff);
hdr = (struct sctphdr *)(skb->data + hdroff);
if (maniptype == IP_NAT_MANIP_SRC) {
/* Get rid of src ip and src pt */
oldip = iph->saddr;
newip = tuple->src.u3.ip;
hdr->source = tuple->src.u.sctp.port;
} else {
/* Get rid of dst ip and dst pt */
oldip = iph->daddr;
newip = tuple->dst.u3.ip;
hdr->dest = tuple->dst.u.sctp.port;
}
crc32 = sctp_start_cksum((u8 *)hdr, skb_headlen(skb) - hdroff);
for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next)
crc32 = sctp_update_cksum((u8 *)skb->data, skb_headlen(skb),
crc32);
crc32 = sctp_end_cksum(crc32);
hdr->checksum = htonl(crc32);
return true;
}
static int
sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
{
unsigned int sctphoff;
struct sctphdr *sh, _sctph;
struct sk_buff *iter;
__le32 cmp;
__le32 val;
__u32 tmp;
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6)
sctphoff = sizeof(struct ipv6hdr);
else
#endif
sctphoff = ip_hdrlen(skb);
sh = skb_header_pointer(skb, sctphoff, sizeof(_sctph), &_sctph);
if (sh == NULL)
return 0;
cmp = sh->checksum;
tmp = sctp_start_cksum((__u8 *) sh, skb_headlen(skb));
skb_walk_frags(skb, iter)
tmp = sctp_update_cksum((__u8 *) iter->data,
skb_headlen(iter), tmp);
val = sctp_end_cksum(tmp);
if (val != cmp) {
/* CRC failure, dump it. */
IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
"Failed checksum for");
return 0;
}
return 1;
}
