Commit a150d122 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nft_meta: add inner match support 



Add support for inner meta matching on:

- NFT_META_PROTOCOL: to match on the ethertype, this can be used
  regardless tunnel protocol provides no link layer header, in that case
  nft_inner sets on the ethertype based on the IP header version field.
- NFT_META_L4PROTO: to match on the layer 4 protocol.

These meta expression are usually autogenerated as dependencies by
userspace nftables.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 0e795b37

include/net/netfilter/nft_meta.h

+6 −0
Original line number Diff line number Diff line
@@ -46,4 +46,10 @@ int nft_meta_set_validate(const struct nft_ctx *ctx, 


bool nft_meta_get_reduce(struct nft_regs_track *track,

			 const struct nft_expr *expr);



struct nft_inner_tun_ctx;

void nft_meta_inner_eval(const struct nft_expr *expr,

			 struct nft_regs *regs, const struct nft_pktinfo *pkt,

			 struct nft_inner_tun_ctx *tun_ctx);



#endif

net/netfilter/nft_inner.c

+8 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables_core.h>

#include <net/netfilter/nf_tables.h>

#include <net/netfilter/nft_meta.h>

#include <net/netfilter/nf_tables_offload.h>

#include <linux/tcp.h>

#include <linux/udp.h>
@@ -28,11 +29,13 @@ struct __nft_expr { 
	const struct nft_expr_ops	*ops;

	union {

		struct nft_payload	payload;

		struct nft_meta		meta;

	} __attribute__((aligned(__alignof__(u64))));

};



enum {

	NFT_INNER_EXPR_PAYLOAD,

	NFT_INNER_EXPR_META,

};



struct nft_inner {
@@ -237,6 +240,9 @@ static void nft_inner_eval(const struct nft_expr *expr, struct nft_regs *regs, 
	case NFT_INNER_EXPR_PAYLOAD:

		nft_payload_inner_eval((struct nft_expr *)&priv->expr, regs, pkt, tun_ctx);

		break;

	case NFT_INNER_EXPR_META:

		nft_meta_inner_eval((struct nft_expr *)&priv->expr, regs, pkt, tun_ctx);

		break;

	default:

		WARN_ON_ONCE(1);

		goto err;
@@ -306,6 +312,8 @@ static int nft_inner_init(const struct nft_ctx *ctx, 


	if (!strcmp(expr_info.ops->type->name, "payload"))

		priv->expr_type = NFT_INNER_EXPR_PAYLOAD;

	else if (!strcmp(expr_info.ops->type->name, "meta"))

		priv->expr_type = NFT_INNER_EXPR_META;

	else

		return -EINVAL;

net/netfilter/nft_meta.c

+62 −0
Original line number Diff line number Diff line
@@ -831,9 +831,71 @@ nft_meta_select_ops(const struct nft_ctx *ctx, 
	return ERR_PTR(-EINVAL);

}



static int nft_meta_inner_init(const struct nft_ctx *ctx,

			       const struct nft_expr *expr,

			       const struct nlattr * const tb[])

{

	struct nft_meta *priv = nft_expr_priv(expr);

	unsigned int len;



	priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));

	switch (priv->key) {

	case NFT_META_PROTOCOL:

		len = sizeof(u16);

		break;

	case NFT_META_L4PROTO:

		len = sizeof(u32);

		break;

	default:

		return -EOPNOTSUPP;

	}

	priv->len = len;



	return nft_parse_register_store(ctx, tb[NFTA_META_DREG], &priv->dreg,

					NULL, NFT_DATA_VALUE, len);

}



void nft_meta_inner_eval(const struct nft_expr *expr,

			 struct nft_regs *regs,

			 const struct nft_pktinfo *pkt,

			 struct nft_inner_tun_ctx *tun_ctx)

{

	const struct nft_meta *priv = nft_expr_priv(expr);

	u32 *dest = &regs->data[priv->dreg];



	switch (priv->key) {

	case NFT_META_PROTOCOL:

		nft_reg_store16(dest, (__force u16)tun_ctx->llproto);

		break;

	case NFT_META_L4PROTO:

		if (!(tun_ctx->flags & NFT_PAYLOAD_CTX_INNER_TH))

			goto err;



		nft_reg_store8(dest, tun_ctx->l4proto);

		break;

	default:

		WARN_ON_ONCE(1);

		goto err;

	}

	return;



err:

	regs->verdict.code = NFT_BREAK;

}

EXPORT_SYMBOL_GPL(nft_meta_inner_eval);



static const struct nft_expr_ops nft_meta_inner_ops = {

	.type		= &nft_meta_type,

	.size		= NFT_EXPR_SIZE(sizeof(struct nft_meta)),

	.init		= nft_meta_inner_init,

	.dump		= nft_meta_get_dump,

	/* direct call to nft_meta_inner_eval(). */

};



struct nft_expr_type nft_meta_type __read_mostly = {

	.name		= "meta",

	.select_ops	= nft_meta_select_ops,

	.inner_ops	= &nft_meta_inner_ops,

	.policy		= nft_meta_policy,

	.maxattr	= NFTA_META_MAX,

	.owner		= THIS_MODULE,