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Commit baae3e62 authored by Patrick McHardy's avatar Patrick McHardy Committed by Pablo Neira Ayuso
Browse files

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: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 75820676

include/net/netfilter/nf_tables.h

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/netfilter/nf_tables_api.c

+24 −21
Original line number Diff line number Diff line
@@ -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++) {

		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,

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);
@@ -617,8 +614,7 @@ 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))

		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))
@@ -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