netfilter: nf_tables: replay request after dropping locks to load chain type

To avoid races, we need to replay to request after dropping the nfnl_mutex
to auto-load the chain type module.

Signed-off-by: Patrick McHardy <kaber@trash.net>
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 d913fb0..7d6a226 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -147,16 +147,20 @@ nf_tables_chain_type_lookup(const struct nft_af_info *afi,
        struct nf_chain_type *type;
 
        type = __nf_tables_chain_type_lookup(afi->family, nla);
+       if (type != NULL)
+               return type;
 #ifdef CONFIG_MODULES
-       if (type == NULL && autoload) {
+       if (autoload) {
                nfnl_unlock(NFNL_SUBSYS_NFTABLES);
                request_module("nft-chain-%u-%*.s", afi->family,
                               nla_len(nla)-1, (const char *)nla_data(nla));
                nfnl_lock(NFNL_SUBSYS_NFTABLES);
                type = __nf_tables_chain_type_lookup(afi->family, nla);
+               if (type != NULL)
+                       return ERR_PTR(-EAGAIN);
        }
 #endif
-       return type;
+       return ERR_PTR(-ENOENT);
 }
 
 static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
@@ -906,8 +910,8 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
                        type = nf_tables_chain_type_lookup(afi,
                                                           nla[NFTA_CHAIN_TYPE],
                                                           create);
-                       if (type == NULL)
-                               return -ENOENT;
+                       if (IS_ERR(type))
+                               return PTR_ERR(type);
                }
 
                err = nla_parse_nested(ha, NFTA_HOOK_MAX, nla[NFTA_CHAIN_HOOK],