2eb0f624b7
This is a patch proposal to support shifted ranges in portmaps. (i.e. tcp/udp incoming port 5000-5100 on WAN redirected to LAN 192.168.1.5:2000-2100) Currently DNAT only works for single port or identical port ranges. (i.e. ports 5000-5100 on WAN interface redirected to a LAN host while original destination port is not altered) When different port ranges are configured, either 'random' mode should be used, or else all incoming connections are mapped onto the first port in the redirect range. (in described example WAN:5000-5100 will all be mapped to 192.168.1.5:2000) This patch introduces a new mode indicated by flag NF_NAT_RANGE_PROTO_OFFSET which uses a base port value to calculate an offset with the destination port present in the incoming stream. That offset is then applied as index within the redirect port range (index modulo rangewidth to handle range overflow). In described example the base port would be 5000. An incoming stream with destination port 5004 would result in an offset value 4 which means that the NAT'ed stream will be using destination port 2004. Other possibilities include deterministic mapping of larger or multiple ranges to a smaller range : WAN:5000-5999 -> LAN:5000-5099 (maps WAN port 5*xx to port 51xx) This patch does not change any current behavior. It just adds new NAT proto range functionality which must be selected via the specific flag when intended to use. A patch for iptables (libipt_DNAT.c + libip6t_DNAT.c) will also be proposed which makes this functionality immediately available. Signed-off-by: Thierry Du Tre <thierry@dtsystems.be> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
/*
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* Copyright (c) 2014 Arturo Borrero Gonzalez <arturo@debian.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nft_redir.h>
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#include <net/netfilter/nf_nat_redirect.h>
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static void nft_redir_ipv6_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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struct nft_redir *priv = nft_expr_priv(expr);
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struct nf_nat_range2 range;
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memset(&range, 0, sizeof(range));
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if (priv->sreg_proto_min) {
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range.min_proto.all = (__force __be16)nft_reg_load16(
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®s->data[priv->sreg_proto_min]);
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range.max_proto.all = (__force __be16)nft_reg_load16(
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®s->data[priv->sreg_proto_max]);
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range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
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}
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range.flags |= priv->flags;
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regs->verdict.code =
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nf_nat_redirect_ipv6(pkt->skb, &range, nft_hook(pkt));
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}
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static void
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nft_redir_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
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{
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nf_ct_netns_put(ctx->net, NFPROTO_IPV6);
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}
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static struct nft_expr_type nft_redir_ipv6_type;
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static const struct nft_expr_ops nft_redir_ipv6_ops = {
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.type = &nft_redir_ipv6_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_redir)),
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.eval = nft_redir_ipv6_eval,
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.init = nft_redir_init,
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.destroy = nft_redir_ipv6_destroy,
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.dump = nft_redir_dump,
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.validate = nft_redir_validate,
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};
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static struct nft_expr_type nft_redir_ipv6_type __read_mostly = {
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.family = NFPROTO_IPV6,
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.name = "redir",
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.ops = &nft_redir_ipv6_ops,
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.policy = nft_redir_policy,
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.maxattr = NFTA_REDIR_MAX,
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.owner = THIS_MODULE,
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};
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static int __init nft_redir_ipv6_module_init(void)
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{
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return nft_register_expr(&nft_redir_ipv6_type);
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}
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static void __exit nft_redir_ipv6_module_exit(void)
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{
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nft_unregister_expr(&nft_redir_ipv6_type);
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}
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module_init(nft_redir_ipv6_module_init);
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module_exit(nft_redir_ipv6_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo@debian.org>");
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MODULE_ALIAS_NFT_AF_EXPR(AF_INET6, "redir");
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