![Jan Engelhardt](/assets/img/avatar_default.png)
Signed-off-by: Jan Engelhardt <jengelh@medozas.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
/*
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* ebt_snat
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*
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* Authors:
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* Bart De Schuymer <bdschuym@pandora.be>
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*
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* June, 2002
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*
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*/
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#include <linux/module.h>
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#include <net/sock.h>
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#include <linux/if_arp.h>
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#include <net/arp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_bridge/ebtables.h>
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#include <linux/netfilter_bridge/ebt_nat.h>
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static unsigned int
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ebt_snat_tg(struct sk_buff *skb, const struct net_device *in,
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const struct net_device *out, unsigned int hook_nr,
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const struct xt_target *target, const void *data)
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{
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const struct ebt_nat_info *info = data;
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if (!skb_make_writable(skb, 0))
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return EBT_DROP;
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memcpy(eth_hdr(skb)->h_source, info->mac, ETH_ALEN);
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if (!(info->target & NAT_ARP_BIT) &&
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eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
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const struct arphdr *ap;
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struct arphdr _ah;
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ap = skb_header_pointer(skb, 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(skb, 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 bool
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ebt_snat_tg_check(const char *tablename, const void *e,
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const struct xt_target *target, void *data,
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unsigned int hookmask)
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{
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const struct ebt_nat_info *info = data;
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int tmp;
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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 false;
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CLEAR_BASE_CHAIN_BIT;
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if (strcmp(tablename, "nat"))
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return false;
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if (hookmask & ~(1 << NF_BR_POST_ROUTING))
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return false;
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if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
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return false;
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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 false;
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return true;
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}
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static struct ebt_target snat __read_mostly = {
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.name = EBT_SNAT_TARGET,
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.revision = 0,
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.family = NFPROTO_BRIDGE,
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.target = ebt_snat_tg,
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.checkentry = ebt_snat_tg_check,
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.targetsize = XT_ALIGN(sizeof(struct ebt_nat_info)),
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.me = THIS_MODULE,
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};
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static int __init ebt_snat_init(void)
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{
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return ebt_register_target(&snat);
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}
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static void __exit ebt_snat_fini(void)
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{
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ebt_unregister_target(&snat);
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}
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module_init(ebt_snat_init);
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module_exit(ebt_snat_fini);
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MODULE_DESCRIPTION("Ebtables: Source MAC address translation");
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MODULE_LICENSE("GPL");
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