Commit 732a8049 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: nft_compat: fix handling of large matchinfo size 



currently matchinfo gets stored in the expression, but some xt matches
are very large.

To handle those we either need to switch nft core to kvmalloc and increase
size limit, or allocate the info blob of large matches separately.

This does the latter, this limits the scope of the changes to
nft_compat.

I picked a threshold of 192, this allows most matches to work as before and
handle only few ones via separate alloation (cgroup, u32, sctp, rt).

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 8bdf1647

net/netfilter/nft_compat.c

+63 −1
Original line number Diff line number Diff line
@@ -36,6 +36,13 @@ struct nft_xt { 
	struct rcu_head		rcu_head;

};



/* Used for matches where *info is larger than X byte */

#define NFT_MATCH_LARGE_THRESH	192



struct nft_xt_match_priv {

	void *info;

};



static bool nft_xt_put(struct nft_xt *xt)

{

	if (--xt->refcnt == 0) {
@@ -352,6 +359,15 @@ static void __nft_match_eval(const struct nft_expr *expr, 
	}

}



static void nft_match_large_eval(const struct nft_expr *expr,

				 struct nft_regs *regs,

				 const struct nft_pktinfo *pkt)

{

	struct nft_xt_match_priv *priv = nft_expr_priv(expr);



	__nft_match_eval(expr, regs, pkt, priv->info);

}



static void nft_match_eval(const struct nft_expr *expr,

			   struct nft_regs *regs,

			   const struct nft_pktinfo *pkt)
@@ -458,6 +474,24 @@ nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr, 
	return __nft_match_init(ctx, expr, tb, nft_expr_priv(expr));

}



static int

nft_match_large_init(const struct nft_ctx *ctx, const struct nft_expr *expr,

		     const struct nlattr * const tb[])

{

	struct nft_xt_match_priv *priv = nft_expr_priv(expr);

	struct xt_match *m = expr->ops->data;

	int ret;



	priv->info = kmalloc(XT_ALIGN(m->matchsize), GFP_KERNEL);

	if (!priv->info)

		return -ENOMEM;



	ret = __nft_match_init(ctx, expr, tb, priv->info);

	if (ret)

		kfree(priv->info);

	return ret;

}



static void

__nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,

		    void *info)
@@ -482,6 +516,15 @@ nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) 
	__nft_match_destroy(ctx, expr, nft_expr_priv(expr));

}



static void

nft_match_large_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)

{

	struct nft_xt_match_priv *priv = nft_expr_priv(expr);



	__nft_match_destroy(ctx, expr, priv->info);

	kfree(priv->info);

}



static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr,

			    void *info)

{
@@ -503,6 +546,13 @@ static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr) 
	return __nft_match_dump(skb, expr, nft_expr_priv(expr));

}



static int nft_match_large_dump(struct sk_buff *skb, const struct nft_expr *e)

{

	struct nft_xt_match_priv *priv = nft_expr_priv(e);



	return __nft_match_dump(skb, e, priv->info);

}



static int nft_match_validate(const struct nft_ctx *ctx,

			      const struct nft_expr *expr,

			      const struct nft_data **data)
@@ -670,6 +720,7 @@ nft_match_select_ops(const struct nft_ctx *ctx, 
{

	struct nft_xt *nft_match;

	struct xt_match *match;

	unsigned int matchsize;

	char *mt_name;

	u32 rev, family;

	int err;
@@ -709,7 +760,6 @@ nft_match_select_ops(const struct nft_ctx *ctx, 


	nft_match->refcnt = 0;

	nft_match->ops.type = &nft_match_type;

	nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));

	nft_match->ops.eval = nft_match_eval;

	nft_match->ops.init = nft_match_init;

	nft_match->ops.destroy = nft_match_destroy;
@@ -717,6 +767,18 @@ nft_match_select_ops(const struct nft_ctx *ctx, 
	nft_match->ops.validate = nft_match_validate;

	nft_match->ops.data = match;



	matchsize = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));

	if (matchsize > NFT_MATCH_LARGE_THRESH) {

		matchsize = NFT_EXPR_SIZE(sizeof(struct nft_xt_match_priv));



		nft_match->ops.eval = nft_match_large_eval;

		nft_match->ops.init = nft_match_large_init;

		nft_match->ops.destroy = nft_match_large_destroy;

		nft_match->ops.dump = nft_match_large_dump;

	}



	nft_match->ops.size = matchsize;



	list_add(&nft_match->head, &nft_match_list);



	return &nft_match->ops;

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