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Commit ed6c4136 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nf_tables: add netdev table to filter from ingress 



This allows us to create netdev tables that contain ingress chains. Use
skb_header_pointer() as we may see shared sk_buffs at this stage.

This change provides access to the existing nf_tables features from the ingress
hook.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent ebddf1a8

include/net/netns/nftables.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ struct netns_nftables { 
	struct nft_af_info	*inet;

	struct nft_af_info	*arp;

	struct nft_af_info	*bridge;

	struct nft_af_info	*netdev;

	unsigned int		base_seq;

	u8			gencursor;

};

net/netfilter/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -456,6 +456,11 @@ config NF_TABLES_INET 
	help

	  This option enables support for a mixed IPv4/IPv6 "inet" table.



config NF_TABLES_NETDEV

	tristate "Netfilter nf_tables netdev tables support"

	help

	  This option enables support for the "netdev" table.



config NFT_EXTHDR

	tristate "Netfilter nf_tables IPv6 exthdr module"

	help

net/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ nf_tables-objs += nft_bitwise.o nft_byteorder.o nft_payload.o 


obj-$(CONFIG_NF_TABLES)		+= nf_tables.o

obj-$(CONFIG_NF_TABLES_INET)	+= nf_tables_inet.o

obj-$(CONFIG_NF_TABLES_NETDEV)	+= nf_tables_netdev.o

obj-$(CONFIG_NFT_COMPAT)	+= nft_compat.o

obj-$(CONFIG_NFT_EXTHDR)	+= nft_exthdr.o

obj-$(CONFIG_NFT_META)		+= nft_meta.o

net/netfilter/nf_tables_netdev.c

0 → 100644
+183 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#include <linux/init.h>

#include <linux/module.h>

#include <net/netfilter/nf_tables.h>

#include <linux/ip.h>

#include <linux/ipv6.h>

#include <net/netfilter/nf_tables_ipv4.h>

#include <net/netfilter/nf_tables_ipv6.h>



static inline void

nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo *pkt,

			    const struct nf_hook_ops *ops, struct sk_buff *skb,

			    const struct nf_hook_state *state)

{

	struct iphdr *iph, _iph;

	u32 len, thoff;



	nft_set_pktinfo(pkt, ops, skb, state);



	iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),

				 &_iph);

	if (!iph)

		return;



	iph = ip_hdr(skb);

	if (iph->ihl < 5 || iph->version != 4)

		return;



	len = ntohs(iph->tot_len);

	thoff = iph->ihl * 4;

	if (skb->len < len)

		return;

	else if (len < thoff)

		return;



	pkt->tprot = iph->protocol;

	pkt->xt.thoff = thoff;

	pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;

}



static inline void

__nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,

			      const struct nf_hook_ops *ops,

			      struct sk_buff *skb,

			      const struct nf_hook_state *state)

{

#if IS_ENABLED(CONFIG_IPV6)

	struct ipv6hdr *ip6h, _ip6h;

	unsigned int thoff = 0;

	unsigned short frag_off;

	int protohdr;

	u32 pkt_len;



	ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),

				  &_ip6h);

	if (!ip6h)

		return;



	if (ip6h->version != 6)

		return;



	pkt_len = ntohs(ip6h->payload_len);

	if (pkt_len + sizeof(*ip6h) > skb->len)

		return;



	protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);

	if (protohdr < 0)

                return;



	pkt->tprot = protohdr;

	pkt->xt.thoff = thoff;

	pkt->xt.fragoff = frag_off;

#endif

}



static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,

					       const struct nf_hook_ops *ops,

					       struct sk_buff *skb,

					       const struct nf_hook_state *state)

{

	nft_set_pktinfo(pkt, ops, skb, state);

	__nft_netdev_set_pktinfo_ipv6(pkt, ops, skb, state);

}



static unsigned int

nft_do_chain_netdev(const struct nf_hook_ops *ops, struct sk_buff *skb,

		    const struct nf_hook_state *state)

{

	struct nft_pktinfo pkt;



	switch (eth_hdr(skb)->h_proto) {

	case htons(ETH_P_IP):

		nft_netdev_set_pktinfo_ipv4(&pkt, ops, skb, state);

		break;

	case htons(ETH_P_IPV6):

		nft_netdev_set_pktinfo_ipv6(&pkt, ops, skb, state);

		break;

	default:

		nft_set_pktinfo(&pkt, ops, skb, state);

		break;

	}



	return nft_do_chain(&pkt, ops);

}



static struct nft_af_info nft_af_netdev __read_mostly = {

	.family		= NFPROTO_NETDEV,

	.nhooks		= NF_NETDEV_NUMHOOKS,

	.owner		= THIS_MODULE,

	.flags		= NFT_AF_NEEDS_DEV,

	.nops		= 1,

	.hooks		= {

		[NF_NETDEV_INGRESS]	= nft_do_chain_netdev,

	},

};



static int nf_tables_netdev_init_net(struct net *net)

{

	net->nft.netdev = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);

	if (net->nft.netdev == NULL)

		return -ENOMEM;



	memcpy(net->nft.netdev, &nft_af_netdev, sizeof(nft_af_netdev));



	if (nft_register_afinfo(net, net->nft.netdev) < 0)

		goto err;



	return 0;

err:

	kfree(net->nft.netdev);

	return -ENOMEM;

}



static void nf_tables_netdev_exit_net(struct net *net)

{

	nft_unregister_afinfo(net->nft.netdev);

	kfree(net->nft.netdev);

}



static struct pernet_operations nf_tables_netdev_net_ops = {

	.init	= nf_tables_netdev_init_net,

	.exit	= nf_tables_netdev_exit_net,

};



static const struct nf_chain_type nft_filter_chain_netdev = {

	.name		= "filter",

	.type		= NFT_CHAIN_T_DEFAULT,

	.family		= NFPROTO_NETDEV,

	.owner		= THIS_MODULE,

	.hook_mask	= (1 << NF_NETDEV_INGRESS),

};



static int __init nf_tables_netdev_init(void)

{

	int ret;



	nft_register_chain_type(&nft_filter_chain_netdev);

	ret = register_pernet_subsys(&nf_tables_netdev_net_ops);

	if (ret < 0)

		nft_unregister_chain_type(&nft_filter_chain_netdev);



	return ret;

}



static void __exit nf_tables_netdev_exit(void)

{

	unregister_pernet_subsys(&nf_tables_netdev_net_ops);

	nft_unregister_chain_type(&nft_filter_chain_netdev);

}



module_init(nf_tables_netdev_init);

module_exit(nf_tables_netdev_exit);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");

MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */