Commit d701d811 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nft_compat: do not dump private area 



Zero pad private area, otherwise we expose private kernel pointer to
userspace. This patch also zeroes the tail area after the ->matchsize
and ->targetsize that results from XT_ALIGN().

Fixes: 0ca743a5 ("netfilter: nf_tables: add compatibility layer for x_tables")
Reported-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 18c0ab87

net/netfilter/nft_compat.c

+22 −2
Original line number Original line Diff line number Diff line
@@ -290,6 +290,24 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) 
		module_put(target->me);

		module_put(target->me);

}

}





static int nft_extension_dump_info(struct sk_buff *skb, int attr,

				   const void *info,

				   unsigned int size, unsigned int user_size)

{

	unsigned int info_size, aligned_size = XT_ALIGN(size);

	struct nlattr *nla;



	nla = nla_reserve(skb, attr, aligned_size);

	if (!nla)

		return -1;



	info_size = user_size ? : size;

	memcpy(nla_data(nla), info, info_size);

	memset(nla_data(nla) + info_size, 0, aligned_size - info_size);



	return 0;

}



static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)

static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)

{

{

	const struct xt_target *target = expr->ops->data;

	const struct xt_target *target = expr->ops->data;
@@ -297,7 +315,8 @@ static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr) 




	if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||

	if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||

	    nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||

	    nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||

	    nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(target->targetsize), info))

	    nft_extension_dump_info(skb, NFTA_TARGET_INFO, info,

				    target->targetsize, target->usersize))

		goto nla_put_failure;

		goto nla_put_failure;





	return 0;

	return 0;
@@ -532,7 +551,8 @@ static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr, 




	if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||

	if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||

	    nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||

	    nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||

	    nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(match->matchsize), info))

	    nft_extension_dump_info(skb, NFTA_MATCH_INFO, info,

				    match->matchsize, match->usersize))

		goto nla_put_failure;

		goto nla_put_failure;





	return 0;

	return 0;

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