netfilter: nf_tables: convert built-in tables/chains to chain types

This patch converts built-in tables/chains to chain types that
allows you to deploy customized table and chain configurations from
userspace.

After this patch, you have to specify the chain type when
creating a new chain:

 add chain ip filter output { type filter hook input priority 0; }
                              ^^^^ ------

The existing chain types after this patch are: filter, route and
nat. Note that tables are just containers of chains with no specific
semantics, which is a significant change with regards to iptables.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 9e924014efe3..779cf951c8de 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -115,6 +115,7 @@ enum nft_table_attributes {
  * @NFTA_CHAIN_HANDLE: numeric handle of the chain (NLA_U64)
  * @NFTA_CHAIN_NAME: name of the chain (NLA_STRING)
  * @NFTA_CHAIN_HOOK: hook specification for basechains (NLA_NESTED: nft_hook_attributes)
+ * @NFTA_CHAIN_TYPE: type name of the string (NLA_NUL_STRING)
  */
 enum nft_chain_attributes {
         NFTA_CHAIN_UNSPEC,
@@ -122,6 +123,7 @@ enum nft_chain_attributes {
         NFTA_CHAIN_HANDLE,
         NFTA_CHAIN_NAME,
         NFTA_CHAIN_HOOK,
+        NFTA_CHAIN_TYPE,
         __NFTA_CHAIN_MAX
 };
 #define NFTA_CHAIN_MAX          (__NFTA_CHAIN_MAX - 1)