diff options
Diffstat (limited to '')
-rw-r--r-- | net/bridge/netfilter/ebt_snat.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_snat.c b/net/bridge/netfilter/ebt_snat.c new file mode 100644 index 000000000..7dfbcdfc3 --- /dev/null +++ b/net/bridge/netfilter/ebt_snat.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ebt_snat + * + * Authors: + * Bart De Schuymer <bdschuym@pandora.be> + * + * June, 2002 + * + */ +#include <linux/module.h> +#include <net/sock.h> +#include <linux/if_arp.h> +#include <net/arp.h> +#include <linux/netfilter.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_bridge/ebtables.h> +#include <linux/netfilter_bridge/ebt_nat.h> + +static unsigned int +ebt_snat_tg(struct sk_buff *skb, const struct xt_action_param *par) +{ + const struct ebt_nat_info *info = par->targinfo; + + if (skb_ensure_writable(skb, 0)) + return EBT_DROP; + + ether_addr_copy(eth_hdr(skb)->h_source, info->mac); + if (!(info->target & NAT_ARP_BIT) && + eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) { + const struct arphdr *ap; + struct arphdr _ah; + + ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah); + if (ap == NULL) + return EBT_DROP; + if (ap->ar_hln != ETH_ALEN) + goto out; + if (skb_store_bits(skb, sizeof(_ah), info->mac, ETH_ALEN)) + return EBT_DROP; + } +out: + return info->target | ~EBT_VERDICT_BITS; +} + +static int ebt_snat_tg_check(const struct xt_tgchk_param *par) +{ + const struct ebt_nat_info *info = par->targinfo; + int tmp; + + tmp = info->target | ~EBT_VERDICT_BITS; + if (BASE_CHAIN && tmp == EBT_RETURN) + return -EINVAL; + + if (ebt_invalid_target(tmp)) + return -EINVAL; + tmp = info->target | EBT_VERDICT_BITS; + if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT) + return -EINVAL; + return 0; +} + +static struct xt_target ebt_snat_tg_reg __read_mostly = { + .name = "snat", + .revision = 0, + .family = NFPROTO_BRIDGE, + .table = "nat", + .hooks = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_POST_ROUTING), + .target = ebt_snat_tg, + .checkentry = ebt_snat_tg_check, + .targetsize = sizeof(struct ebt_nat_info), + .me = THIS_MODULE, +}; + +static int __init ebt_snat_init(void) +{ + return xt_register_target(&ebt_snat_tg_reg); +} + +static void __exit ebt_snat_fini(void) +{ + xt_unregister_target(&ebt_snat_tg_reg); +} + +module_init(ebt_snat_init); +module_exit(ebt_snat_fini); +MODULE_DESCRIPTION("Ebtables: Source MAC address translation"); +MODULE_LICENSE("GPL"); |