Commit c8d7b98b authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: move nf_send_resetX() code to nf_reject_ipvX modules 



Move nf_send_reset() and nf_send_reset6() to nf_reject_ipv4 and
nf_reject_ipv6 respectively. This code is shared by x_tables and
nf_tables.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 51b0a5d8

include/net/netfilter/ipv4/nf_reject.h

+1 −117
Original line number Diff line number Diff line 
#ifndef _IPV4_NF_REJECT_H

#define _IPV4_NF_REJECT_H



#include <net/ip.h>

#include <net/tcp.h>

#include <net/route.h>

#include <net/dst.h>

#include <net/icmp.h>



static inline void nf_send_unreach(struct sk_buff *skb_in, int code)
@@ -12,118 +8,6 @@ static inline void nf_send_unreach(struct sk_buff *skb_in, int code) 
	icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);

}



/* Send RST reply */

static void nf_send_reset(struct sk_buff *oldskb, int hook)

{

	struct sk_buff *nskb;

	const struct iphdr *oiph;

	struct iphdr *niph;

	const struct tcphdr *oth;

	struct tcphdr _otcph, *tcph;



	/* IP header checks: fragment. */

	if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))

		return;



	oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),

				 sizeof(_otcph), &_otcph);

	if (oth == NULL)

		return;



	/* No RST for RST. */

	if (oth->rst)

		return;



	if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))

		return;



	/* Check checksum */

	if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))

		return;

	oiph = ip_hdr(oldskb);



	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +

			 LL_MAX_HEADER, GFP_ATOMIC);

	if (!nskb)

		return;



	skb_reserve(nskb, LL_MAX_HEADER);



	skb_reset_network_header(nskb);

	niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));

	niph->version	= 4;

	niph->ihl	= sizeof(struct iphdr) / 4;

	niph->tos	= 0;

	niph->id	= 0;

	niph->frag_off	= htons(IP_DF);

	niph->protocol	= IPPROTO_TCP;

	niph->check	= 0;

	niph->saddr	= oiph->daddr;

	niph->daddr	= oiph->saddr;



	skb_reset_transport_header(nskb);

	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));

	memset(tcph, 0, sizeof(*tcph));

	tcph->source	= oth->dest;

	tcph->dest	= oth->source;

	tcph->doff	= sizeof(struct tcphdr) / 4;



	if (oth->ack)

		tcph->seq = oth->ack_seq;

	else {

		tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +

				      oldskb->len - ip_hdrlen(oldskb) -

				      (oth->doff << 2));

		tcph->ack = 1;

	}



	tcph->rst	= 1;

	tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr,

				    niph->daddr, 0);

	nskb->ip_summed = CHECKSUM_PARTIAL;

	nskb->csum_start = (unsigned char *)tcph - nskb->head;

	nskb->csum_offset = offsetof(struct tcphdr, check);



	/* ip_route_me_harder expects skb->dst to be set */

	skb_dst_set_noref(nskb, skb_dst(oldskb));



	nskb->protocol = htons(ETH_P_IP);

	if (ip_route_me_harder(nskb, RTN_UNSPEC))

		goto free_nskb;



	niph->ttl	= ip4_dst_hoplimit(skb_dst(nskb));



	/* "Never happens" */

	if (nskb->len > dst_mtu(skb_dst(nskb)))

		goto free_nskb;



	nf_ct_attach(nskb, oldskb);



#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)

	/* If we use ip_local_out for bridged traffic, the MAC source on

	 * the RST will be ours, instead of the destination's.  This confuses

	 * some routers/firewalls, and they drop the packet.  So we need to

	 * build the eth header using the original destination's MAC as the

	 * source, and send the RST packet directly.

	 */

	if (oldskb->nf_bridge) {

		struct ethhdr *oeth = eth_hdr(oldskb);

		nskb->dev = oldskb->nf_bridge->physindev;

		niph->tot_len = htons(nskb->len);

		ip_send_check(niph);

		if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),

				    oeth->h_source, oeth->h_dest, nskb->len) < 0)

			goto free_nskb;

		dev_queue_xmit(nskb);

	} else

#endif

		ip_local_out(nskb);



	return;



 free_nskb:

	kfree_skb(nskb);

}



void nf_send_reset(struct sk_buff *oldskb, int hook);



#endif /* _IPV4_NF_REJECT_H */

net/ipv4/netfilter/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -61,8 +61,13 @@ config NFT_CHAIN_ROUTE_IPV4 
	  fields such as the source, destination, type of service and

	  the packet mark.



config NF_REJECT_IPV4

	tristate "IPv4 packet rejection"

	default m if NETFILTER_ADVANCED=n



config NFT_REJECT_IPV4

	depends on NF_TABLES_IPV4

	select NF_REJECT_IPV4

	default NFT_REJECT

	tristate
@@ -208,6 +213,7 @@ config IP_NF_FILTER 
config IP_NF_TARGET_REJECT

	tristate "REJECT target support"

	depends on IP_NF_FILTER

	select NF_REJECT_IPV4

	default m if NETFILTER_ADVANCED=n

	help

	  The REJECT target allows a filtering rule to specify that an ICMP

net/ipv4/netfilter/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o 
obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o

obj-$(CONFIG_NF_LOG_IPV4) += nf_log_ipv4.o



# reject

obj-$(CONFIG_NF_REJECT_IPV4) += nf_reject_ipv4.o



# NAT helpers (nf_conntrack)

obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o

obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o

net/ipv4/netfilter/nf_reject_ipv4.c

0 → 100644
+127 −0
Original line number Diff line number Diff line 
/* (C) 1999-2001 Paul `Rusty' Russell

 * (C) 2002-2004 Netfilter Core Team <coreteam@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 <net/ip.h>

#include <net/tcp.h>

#include <net/route.h>

#include <net/dst.h>

#include <linux/netfilter_ipv4.h>



/* Send RST reply */

void nf_send_reset(struct sk_buff *oldskb, int hook)

{

	struct sk_buff *nskb;

	const struct iphdr *oiph;

	struct iphdr *niph;

	const struct tcphdr *oth;

	struct tcphdr _otcph, *tcph;



	/* IP header checks: fragment. */

	if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))

		return;



	oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),

				 sizeof(_otcph), &_otcph);

	if (oth == NULL)

		return;



	/* No RST for RST. */

	if (oth->rst)

		return;



	if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))

		return;



	/* Check checksum */

	if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))

		return;

	oiph = ip_hdr(oldskb);



	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +

			 LL_MAX_HEADER, GFP_ATOMIC);

	if (!nskb)

		return;



	skb_reserve(nskb, LL_MAX_HEADER);



	skb_reset_network_header(nskb);

	niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));

	niph->version	= 4;

	niph->ihl	= sizeof(struct iphdr) / 4;

	niph->tos	= 0;

	niph->id	= 0;

	niph->frag_off	= htons(IP_DF);

	niph->protocol	= IPPROTO_TCP;

	niph->check	= 0;

	niph->saddr	= oiph->daddr;

	niph->daddr	= oiph->saddr;



	skb_reset_transport_header(nskb);

	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));

	memset(tcph, 0, sizeof(*tcph));

	tcph->source	= oth->dest;

	tcph->dest	= oth->source;

	tcph->doff	= sizeof(struct tcphdr) / 4;



	if (oth->ack)

		tcph->seq = oth->ack_seq;

	else {

		tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +

				      oldskb->len - ip_hdrlen(oldskb) -

				      (oth->doff << 2));

		tcph->ack = 1;

	}



	tcph->rst	= 1;

	tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr,

				    niph->daddr, 0);

	nskb->ip_summed = CHECKSUM_PARTIAL;

	nskb->csum_start = (unsigned char *)tcph - nskb->head;

	nskb->csum_offset = offsetof(struct tcphdr, check);



	/* ip_route_me_harder expects skb->dst to be set */

	skb_dst_set_noref(nskb, skb_dst(oldskb));



	nskb->protocol = htons(ETH_P_IP);

	if (ip_route_me_harder(nskb, RTN_UNSPEC))

		goto free_nskb;



	niph->ttl	= ip4_dst_hoplimit(skb_dst(nskb));



	/* "Never happens" */

	if (nskb->len > dst_mtu(skb_dst(nskb)))

		goto free_nskb;



	nf_ct_attach(nskb, oldskb);



#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)

	/* If we use ip_local_out for bridged traffic, the MAC source on

	 * the RST will be ours, instead of the destination's.  This confuses

	 * some routers/firewalls, and they drop the packet.  So we need to

	 * build the eth header using the original destination's MAC as the

	 * source, and send the RST packet directly.

	 */

	if (oldskb->nf_bridge) {

		struct ethhdr *oeth = eth_hdr(oldskb);

		nskb->dev = oldskb->nf_bridge->physindev;

		niph->tot_len = htons(nskb->len);

		ip_send_check(niph);

		if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),

				    oeth->h_source, oeth->h_dest, nskb->len) < 0)

			goto free_nskb;

		dev_queue_xmit(nskb);

	} else

#endif

		ip_local_out(nskb);



	return;



 free_nskb:

	kfree_skb(nskb);

}

EXPORT_SYMBOL_GPL(nf_send_reset);

net/ipv6/netfilter/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -40,8 +40,13 @@ config NFT_CHAIN_ROUTE_IPV6 
	  fields such as the source, destination, flowlabel, hop-limit and

	  the packet mark.



config NF_REJECT_IPV6

	tristate "IPv6 packet rejection"

	default m if NETFILTER_ADVANCED=n



config NFT_REJECT_IPV6

	depends on NF_TABLES_IPV6

	select NF_REJECT_IPV6

	default NFT_REJECT

	tristate
@@ -208,6 +213,7 @@ config IP6_NF_FILTER 
config IP6_NF_TARGET_REJECT

	tristate "REJECT target support"

	depends on IP6_NF_FILTER

	select NF_REJECT_IPV6

	default m if NETFILTER_ADVANCED=n

	help

	  The REJECT target allows a filtering rule to specify that an ICMPv6