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[NETFILTER]: ebtables: add --snap-arp option

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The attached patch adds --snat-arp support, which makes it possible to
change the source mac address in both the mac header and the arp header
with one rule.

Signed-off-by: Bart De Schuymer <bdschuym@pandora.be>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Bart De Schuymer 2006-11-29 02:35:40 +01:00 committed by David S. Miller
parent baf7b1e112
commit d12cdc3ccf
4 changed files with 32 additions and 6 deletions
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1
include/linux/netfilter_bridge/ebt_nat.h
View File

@ -1,6 +1,7 @@
#ifndef __LINUX_BRIDGE_EBT_NAT_H #ifndef __LINUX_BRIDGE_EBT_NAT_H
#define __LINUX_BRIDGE_EBT_NAT_H #define __LINUX_BRIDGE_EBT_NAT_H
#define NAT_ARP_BIT (0x00000010)
struct ebt_nat_info struct ebt_nat_info
{ {
unsigned char mac[ETH_ALEN]; unsigned char mac[ETH_ALEN];

4
include/linux/netfilter_bridge/ebtables.h
View File

@ -26,6 +26,10 @@
#define EBT_CONTINUE -3 #define EBT_CONTINUE -3
#define EBT_RETURN -4 #define EBT_RETURN -4
#define NUM_STANDARD_TARGETS 4 #define NUM_STANDARD_TARGETS 4
/* ebtables target modules store the verdict inside an int. We can
* reclaim a part of this int for backwards compatible extensions.
* The 4 lsb are more than enough to store the verdict. */
#define EBT_VERDICT_BITS 0x0000000F
struct ebt_counter struct ebt_counter
{ {

6
net/bridge/netfilter/ebt_mark.c
View File

@ -33,7 +33,7 @@ static int ebt_target_mark(struct sk_buff **pskb, unsigned int hooknr,
else else
(*pskb)->mark ^= info->mark; (*pskb)->mark ^= info->mark;
return info->target | -16; return info->target | ~EBT_VERDICT_BITS;
} }
static int ebt_target_mark_check(const char *tablename, unsigned int hookmask, static int ebt_target_mark_check(const char *tablename, unsigned int hookmask,
@ -44,13 +44,13 @@ static int ebt_target_mark_check(const char *tablename, unsigned int hookmask,
if (datalen != EBT_ALIGN(sizeof(struct ebt_mark_t_info))) if (datalen != EBT_ALIGN(sizeof(struct ebt_mark_t_info)))
return -EINVAL; return -EINVAL;
tmp = info->target | -16; tmp = info->target | ~EBT_VERDICT_BITS;
if (BASE_CHAIN && tmp == EBT_RETURN) if (BASE_CHAIN && tmp == EBT_RETURN)
return -EINVAL; return -EINVAL;
CLEAR_BASE_CHAIN_BIT; CLEAR_BASE_CHAIN_BIT;
if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0) if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
return -EINVAL; return -EINVAL;
tmp = info->target & -16; tmp = info->target & ~EBT_VERDICT_BITS;
if (tmp != MARK_SET_VALUE && tmp != MARK_OR_VALUE && if (tmp != MARK_SET_VALUE && tmp != MARK_OR_VALUE &&
tmp != MARK_AND_VALUE && tmp != MARK_XOR_VALUE) tmp != MARK_AND_VALUE && tmp != MARK_XOR_VALUE)
return -EINVAL; return -EINVAL;

27
net/bridge/netfilter/ebt_snat.c
View File

@ -12,6 +12,8 @@
#include <linux/netfilter_bridge/ebt_nat.h> #include <linux/netfilter_bridge/ebt_nat.h>
#include <linux/module.h> #include <linux/module.h>
#include <net/sock.h> #include <net/sock.h>
#include <linux/if_arp.h>
#include <net/arp.h>
static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr, static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr,
const struct net_device *in, const struct net_device *out, const struct net_device *in, const struct net_device *out,
@ -31,24 +33,43 @@ static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr,
*pskb = nskb; *pskb = nskb;
} }
memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN); memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN);
return info->target; if (!(info->target & NAT_ARP_BIT) &&
eth_hdr(*pskb)->h_proto == htons(ETH_P_ARP)) {
struct arphdr _ah, *ap;
ap = skb_header_pointer(*pskb, 0, sizeof(_ah), &_ah);
if (ap == NULL)
return EBT_DROP;
if (ap->ar_hln != ETH_ALEN)
goto out;
if (skb_store_bits(*pskb, sizeof(_ah), info->mac,ETH_ALEN))
return EBT_DROP;
}
out:
return info->target | ~EBT_VERDICT_BITS;
} }
static int ebt_target_snat_check(const char *tablename, unsigned int hookmask, static int ebt_target_snat_check(const char *tablename, unsigned int hookmask,
const struct ebt_entry *e, void *data, unsigned int datalen) const struct ebt_entry *e, void *data, unsigned int datalen)
{ {
struct ebt_nat_info *info = (struct ebt_nat_info *) data; struct ebt_nat_info *info = (struct ebt_nat_info *) data;
int tmp;
if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info))) if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info)))
return -EINVAL; return -EINVAL;
if (BASE_CHAIN && info->target == EBT_RETURN) tmp = info->target | ~EBT_VERDICT_BITS;
if (BASE_CHAIN && tmp == EBT_RETURN)
return -EINVAL; return -EINVAL;
CLEAR_BASE_CHAIN_BIT; CLEAR_BASE_CHAIN_BIT;
if (strcmp(tablename, "nat")) if (strcmp(tablename, "nat"))
return -EINVAL; return -EINVAL;
if (hookmask & ~(1 << NF_BR_POST_ROUTING)) if (hookmask & ~(1 << NF_BR_POST_ROUTING))
return -EINVAL; return -EINVAL;
if (INVALID_TARGET)
if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
return -EINVAL;
tmp = info->target | EBT_VERDICT_BITS;
if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
return -EINVAL; return -EINVAL;
return 0; return 0;
} }