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Commit c918687f authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
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netfilter: nft_compat: relax chain type validation 



Check for nat chain dependency only, which is the one that can
actually crash the kernel. Don't care if mangle, filter and security
specific match and targets are used out of their scope, they are
harmless.

This restores iptables-compat with mangle specific match/target when
used out of the OUTPUT chain, that are actually emulated through filter
chains, which broke when performing strict validation.

Fixes: f3f5dded ("netfilter: nft_compat: validate chain type in match/target")
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 2daf1b4d

net/netfilter/nft_compat.c

+2 −30
Original line number Diff line number Diff line
@@ -21,45 +21,17 @@ 
#include <linux/netfilter_ipv6/ip6_tables.h>

#include <net/netfilter/nf_tables.h>



static const struct {

       const char	*name;

       u8		type;

} table_to_chaintype[] = {

       { "filter",     NFT_CHAIN_T_DEFAULT },

       { "raw",        NFT_CHAIN_T_DEFAULT },

       { "security",   NFT_CHAIN_T_DEFAULT },

       { "mangle",     NFT_CHAIN_T_ROUTE },

       { "nat",        NFT_CHAIN_T_NAT },

       { },

};



static int nft_compat_table_to_chaintype(const char *table)

{

	int i;



	for (i = 0; table_to_chaintype[i].name != NULL; i++) {

		if (strcmp(table_to_chaintype[i].name, table) == 0)

			return table_to_chaintype[i].type;

	}



	return -1;

}



static int nft_compat_chain_validate_dependency(const char *tablename,

						const struct nft_chain *chain)

{

	enum nft_chain_type type;

	const struct nft_base_chain *basechain;



	if (!tablename || !(chain->flags & NFT_BASE_CHAIN))

		return 0;



	type = nft_compat_table_to_chaintype(tablename);

	if (type < 0)

		return -EINVAL;



	basechain = nft_base_chain(chain);

	if (basechain->type->type != type)

	if (strcmp(tablename, "nat") == 0 &&

	    basechain->type->type != NFT_CHAIN_T_NAT)

		return -EINVAL;



	return 0;