NFTA_CHAIN_USERDATA
[NFTA_CHAIN_USERDATA] = { .type = NLA_BINARY,
nla_put(skb, NFTA_CHAIN_USERDATA, chain->udlen, chain->udata))
if (nla[NFTA_CHAIN_USERDATA]) {
chain->udata = nla_memdup(nla[NFTA_CHAIN_USERDATA], GFP_KERNEL_ACCOUNT);
chain->udlen = nla_len(nla[NFTA_CHAIN_USERDATA]);