netfilter: nf_tables: fix chain type module reference handling

The chain type module reference handling makes no sense at all: we take
a reference immediately when the module is registered, preventing the
module from ever being unloaded.

Fix by taking a reference when we're actually creating a chain of the
chain type and release the reference when destroying the chain.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 5d2b703..e9b9786 100644 (file)
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -436,7 +436,7 @@ struct nft_stats {
  */
 struct nft_base_chain {
        struct nf_hook_ops              ops[NFT_HOOK_OPS_MAX];
-       enum nft_chain_type             type;
+       struct nf_chain_type            *type;
        u8                              policy;
        struct nft_stats __percpu       *stats;
        struct nft_chain                chain;

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 290472c..d913fb0 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -126,27 +126,29 @@ static inline u64 nf_tables_alloc_handle(struct nft_table *table)
 
 static struct nf_chain_type *chain_type[AF_MAX][NFT_CHAIN_T_MAX];
 
-static int __nf_tables_chain_type_lookup(int family, const struct nlattr *nla)
+static struct nf_chain_type *
+__nf_tables_chain_type_lookup(int family, const struct nlattr *nla)
 {
        int i;
 
-       for (i=0; i<NFT_CHAIN_T_MAX; i++) {
+       for (i = 0; i < NFT_CHAIN_T_MAX; i++) {
                if (chain_type[family][i] != NULL &&
                    !nla_strcmp(nla, chain_type[family][i]->name))
-                       return i;
+                       return chain_type[family][i];
        }
-       return -1;
+       return NULL;
 }
 
-static int nf_tables_chain_type_lookup(const struct nft_af_info *afi,
-                                      const struct nlattr *nla,
-                                      bool autoload)
+static struct nf_chain_type *
+nf_tables_chain_type_lookup(const struct nft_af_info *afi,
+                           const struct nlattr *nla,
+                           bool autoload)
 {
-       int type;
+       struct nf_chain_type *type;
 
        type = __nf_tables_chain_type_lookup(afi->family, nla);
 #ifdef CONFIG_MODULES
-       if (type < 0 && autoload) {
+       if (type == NULL && autoload) {
                nfnl_unlock(NFNL_SUBSYS_NFTABLES);
                request_module("nft-chain-%u-%*.s", afi->family,
                               nla_len(nla)-1, (const char *)nla_data(nla));
@@ -478,10 +480,6 @@ int nft_register_chain_type(struct nf_chain_type *ctype)
                err = -EBUSY;
                goto out;
        }
-
-       if (!try_module_get(ctype->me))
-               goto out;
-
        chain_type[ctype->family][ctype->type] = ctype;
 out:
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
@@ -493,7 +491,6 @@ void nft_unregister_chain_type(struct nf_chain_type *ctype)
 {
        nfnl_lock(NFNL_SUBSYS_NFTABLES);
        chain_type[ctype->family][ctype->type] = NULL;
-       module_put(ctype->me);
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
 }
 EXPORT_SYMBOL_GPL(nft_unregister_chain_type);
@@ -617,9 +614,8 @@ static int nf_tables_fill_chain_info(struct sk_buff *skb, u32 portid, u32 seq,
                                 htonl(basechain->policy)))
                        goto nla_put_failure;
 
-               if (nla_put_string(skb, NFTA_CHAIN_TYPE,
-                       chain_type[ops->pf][nft_base_chain(chain)->type]->name))
-                               goto nla_put_failure;
+               if (nla_put_string(skb, NFTA_CHAIN_TYPE, basechain->type->name))
+                       goto nla_put_failure;
 
                if (nft_dump_stats(skb, nft_base_chain(chain)->stats))
                        goto nla_put_failure;
@@ -900,16 +896,17 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
                return -EOVERFLOW;
 
        if (nla[NFTA_CHAIN_HOOK]) {
+               struct nf_chain_type *type;
                struct nf_hook_ops *ops;
                nf_hookfn *hookfn;
                u32 hooknum, priority;
-               int type = NFT_CHAIN_T_DEFAULT;
 
+               type = chain_type[family][NFT_CHAIN_T_DEFAULT];
                if (nla[NFTA_CHAIN_TYPE]) {
                        type = nf_tables_chain_type_lookup(afi,
                                                           nla[NFTA_CHAIN_TYPE],
                                                           create);
-                       if (type < 0)
+                       if (type == NULL)
                                return -ENOENT;
                }
 
@@ -926,9 +923,11 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
                        return -EINVAL;
                priority = ntohl(nla_get_be32(ha[NFTA_HOOK_PRIORITY]));
 
-               if (!(chain_type[family][type]->hook_mask & (1 << hooknum)))
+               if (!(type->hook_mask & (1 << hooknum)))
                        return -EOPNOTSUPP;
-               hookfn = chain_type[family][type]->fn[hooknum];
+               if (!try_module_get(type->me))
+                       return -ENOENT;
+               hookfn = type->fn[hooknum];
 
                basechain = kzalloc(sizeof(*basechain), GFP_KERNEL);
                if (basechain == NULL)
@@ -938,6 +937,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
                        err = nf_tables_counters(basechain,
                                                 nla[NFTA_CHAIN_COUNTERS]);
                        if (err < 0) {
+                               module_put(type->me);
                                kfree(basechain);
                                return err;
                        }
@@ -946,6 +946,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 
                        newstats = alloc_percpu(struct nft_stats);
                        if (newstats == NULL) {
+                               module_put(type->me);
                                kfree(basechain);
                                return -ENOMEM;
                        }
@@ -987,6 +988,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
            chain->flags & NFT_BASE_CHAIN) {
                err = nf_register_hooks(nft_base_chain(chain)->ops, afi->nops);
                if (err < 0) {
+                       module_put(basechain->type->me);
                        free_percpu(basechain->stats);
                        kfree(basechain);
                        return err;
@@ -1007,6 +1009,7 @@ static void nf_tables_rcu_chain_destroy(struct rcu_head *head)
        BUG_ON(chain->use > 0);
 
        if (chain->flags & NFT_BASE_CHAIN) {
+               module_put(nft_base_chain(chain)->type->me);
                free_percpu(nft_base_chain(chain)->stats);
                kfree(nft_base_chain(chain));
        } else