netfilter: nf_tables: Reject tables of unsupported family

An nftables family is merely a hollow container, its family just a
number and such not reliant on compile-time options other than nftables
support itself. Add an artificial check so attempts at using a family
the kernel can't support fail as early as possible. This helps user
space detect kernels which lack e.g. NFPROTO_INET.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 9cd1d7a..3168ad8 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1072,6 +1072,30 @@ static int nft_objname_hash_cmp(struct rhashtable_compare_arg *arg,
        return strcmp(obj->key.name, k->name);
 }
 
+static bool nft_supported_family(u8 family)
+{
+       return false
+#ifdef CONFIG_NF_TABLES_INET
+               || family == NFPROTO_INET
+#endif
+#ifdef CONFIG_NF_TABLES_IPV4
+               || family == NFPROTO_IPV4
+#endif
+#ifdef CONFIG_NF_TABLES_ARP
+               || family == NFPROTO_ARP
+#endif
+#ifdef CONFIG_NF_TABLES_NETDEV
+               || family == NFPROTO_NETDEV
+#endif
+#if IS_ENABLED(CONFIG_NF_TABLES_BRIDGE)
+               || family == NFPROTO_BRIDGE
+#endif
+#ifdef CONFIG_NF_TABLES_IPV6
+               || family == NFPROTO_IPV6
+#endif
+               ;
+}
+
 static int nf_tables_newtable(struct sk_buff *skb, const struct nfnl_info *info,
                              const struct nlattr * const nla[])
 {
@@ -1086,6 +1110,9 @@ static int nf_tables_newtable(struct sk_buff *skb, const struct nfnl_info *info,
        u32 flags = 0;
        int err;
 
+       if (!nft_supported_family(family))
+               return -EOPNOTSUPP;
+
        lockdep_assert_held(&nft_net->commit_mutex);
        attr = nla[NFTA_TABLE_NAME];
        table = nft_table_lookup(net, attr, family, genmask,