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kernel
os
linux
[NETFILTER]: ebtables: add --snap-arp option
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>
authored by
Bart De Schuymer
and committed by
David S. Miller
d12cdc3c
baf7b1e1
+32
-6
+1
include/linux/netfilter_bridge/ebt_nat.h
+1
include/linux/netfilter_bridge/ebt_nat.h
+4
include/linux/netfilter_bridge/ebtables.h
+4
include/linux/netfilter_bridge/ebtables.h
···
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#define EBT_CONTINUE -3
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#define EBT_RETURN -4
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#define NUM_STANDARD_TARGETS 4
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+
/* ebtables target modules store the verdict inside an int. We can
30
+
* reclaim a part of this int for backwards compatible extensions.
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+
* The 4 lsb are more than enough to store the verdict. */
32
+
#define EBT_VERDICT_BITS 0x0000000F
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struct ebt_counter
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{
+3
-3
net/bridge/netfilter/ebt_mark.c
+3
-3
net/bridge/netfilter/ebt_mark.c
···
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else
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(*pskb)->mark ^= info->mark;
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-
return info->target | -16;
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+
return info->target | ~EBT_VERDICT_BITS;
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}
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static int ebt_target_mark_check(const char *tablename, unsigned int hookmask,
···
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if (datalen != EBT_ALIGN(sizeof(struct ebt_mark_t_info)))
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return -EINVAL;
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-
tmp = info->target | -16;
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+
tmp = info->target | ~EBT_VERDICT_BITS;
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if (BASE_CHAIN && tmp == EBT_RETURN)
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return -EINVAL;
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CLEAR_BASE_CHAIN_BIT;
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if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
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return -EINVAL;
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-
tmp = info->target & -16;
53
+
tmp = info->target & ~EBT_VERDICT_BITS;
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if (tmp != MARK_SET_VALUE && tmp != MARK_OR_VALUE &&
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tmp != MARK_AND_VALUE && tmp != MARK_XOR_VALUE)
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return -EINVAL;
+24
-3
net/bridge/netfilter/ebt_snat.c
+24
-3
net/bridge/netfilter/ebt_snat.c
···
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#include <linux/netfilter_bridge/ebt_nat.h>
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#include <linux/module.h>
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#include <net/sock.h>
15
+
#include <linux/if_arp.h>
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+
#include <net/arp.h>
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static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr,
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const struct net_device *in, const struct net_device *out,
···
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*pskb = nskb;
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}
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memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN);
36
-
return info->target;
34
+
if (!(info->target & NAT_ARP_BIT) &&
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+
eth_hdr(*pskb)->h_proto == htons(ETH_P_ARP)) {
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+
struct arphdr _ah, *ap;
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+
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ap = skb_header_pointer(*pskb, 0, sizeof(_ah), &_ah);
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+
if (ap == NULL)
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+
return EBT_DROP;
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+
if (ap->ar_hln != ETH_ALEN)
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+
goto out;
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+
if (skb_store_bits(*pskb, sizeof(_ah), info->mac,ETH_ALEN))
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+
return EBT_DROP;
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+
}
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+
out:
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+
return info->target | ~EBT_VERDICT_BITS;
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}
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static int ebt_target_snat_check(const char *tablename, unsigned int hookmask,
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const struct ebt_entry *e, void *data, unsigned int datalen)
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{
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struct ebt_nat_info *info = (struct ebt_nat_info *) data;
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+
int tmp;
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if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info)))
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return -EINVAL;
46
-
if (BASE_CHAIN && info->target == EBT_RETURN)
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+
tmp = info->target | ~EBT_VERDICT_BITS;
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+
if (BASE_CHAIN && tmp == EBT_RETURN)
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return -EINVAL;
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CLEAR_BASE_CHAIN_BIT;
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if (strcmp(tablename, "nat"))
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return -EINVAL;
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if (hookmask & ~(1 << NF_BR_POST_ROUTING))
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return -EINVAL;
53
-
if (INVALID_TARGET)
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+
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+
if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
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+
return -EINVAL;
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+
tmp = info->target | EBT_VERDICT_BITS;
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+
if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
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return -EINVAL;
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return 0;
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}