123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153 |
- /*
- * Copyright (c) 2011, 2012 Patrick McHardy <kaber@trash.net>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/ipv6.h>
- #include <net/ipv6.h>
- #include <linux/netfilter.h>
- #include <linux/netfilter_ipv6.h>
- #include <linux/netfilter_ipv6/ip6t_NPT.h>
- #include <linux/netfilter/x_tables.h>
- static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
- {
- struct ip6t_npt_tginfo *npt = par->targinfo;
- struct in6_addr pfx;
- __wsum src_sum, dst_sum;
- if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
- return -EINVAL;
- /* Ensure that LSB of prefix is zero */
- ipv6_addr_prefix(&pfx, &npt->src_pfx.in6, npt->src_pfx_len);
- if (!ipv6_addr_equal(&pfx, &npt->src_pfx.in6))
- return -EINVAL;
- ipv6_addr_prefix(&pfx, &npt->dst_pfx.in6, npt->dst_pfx_len);
- if (!ipv6_addr_equal(&pfx, &npt->dst_pfx.in6))
- return -EINVAL;
- src_sum = csum_partial(&npt->src_pfx.in6, sizeof(npt->src_pfx.in6), 0);
- dst_sum = csum_partial(&npt->dst_pfx.in6, sizeof(npt->dst_pfx.in6), 0);
- npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum));
- return 0;
- }
- static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
- struct in6_addr *addr)
- {
- unsigned int pfx_len;
- unsigned int i, idx;
- __be32 mask;
- __sum16 sum;
- pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len);
- for (i = 0; i < pfx_len; i += 32) {
- if (pfx_len - i >= 32)
- mask = 0;
- else
- mask = htonl((1 << (i - pfx_len + 32)) - 1);
- idx = i / 32;
- addr->s6_addr32[idx] &= mask;
- addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx];
- }
- if (pfx_len <= 48)
- idx = 3;
- else {
- for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) {
- if ((__force __sum16)addr->s6_addr16[idx] !=
- CSUM_MANGLED_0)
- break;
- }
- if (idx == ARRAY_SIZE(addr->s6_addr16))
- return false;
- }
- sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]),
- csum_unfold(npt->adjustment)));
- if (sum == CSUM_MANGLED_0)
- sum = 0;
- *(__force __sum16 *)&addr->s6_addr16[idx] = sum;
- return true;
- }
- static unsigned int
- ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
- {
- const struct ip6t_npt_tginfo *npt = par->targinfo;
- if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) {
- icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
- offsetof(struct ipv6hdr, saddr));
- return NF_DROP;
- }
- return XT_CONTINUE;
- }
- static unsigned int
- ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
- {
- const struct ip6t_npt_tginfo *npt = par->targinfo;
- if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) {
- icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
- offsetof(struct ipv6hdr, daddr));
- return NF_DROP;
- }
- return XT_CONTINUE;
- }
- static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
- {
- .name = "SNPT",
- .table = "mangle",
- .target = ip6t_snpt_tg,
- .targetsize = sizeof(struct ip6t_npt_tginfo),
- .checkentry = ip6t_npt_checkentry,
- .family = NFPROTO_IPV6,
- .hooks = (1 << NF_INET_LOCAL_IN) |
- (1 << NF_INET_POST_ROUTING),
- .me = THIS_MODULE,
- },
- {
- .name = "DNPT",
- .table = "mangle",
- .target = ip6t_dnpt_tg,
- .targetsize = sizeof(struct ip6t_npt_tginfo),
- .checkentry = ip6t_npt_checkentry,
- .family = NFPROTO_IPV6,
- .hooks = (1 << NF_INET_PRE_ROUTING) |
- (1 << NF_INET_LOCAL_OUT),
- .me = THIS_MODULE,
- },
- };
- static int __init ip6t_npt_init(void)
- {
- return xt_register_targets(ip6t_npt_target_reg,
- ARRAY_SIZE(ip6t_npt_target_reg));
- }
- static void __exit ip6t_npt_exit(void)
- {
- xt_unregister_targets(ip6t_npt_target_reg,
- ARRAY_SIZE(ip6t_npt_target_reg));
- }
- module_init(ip6t_npt_init);
- module_exit(ip6t_npt_exit);
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)");
- MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
- MODULE_ALIAS("ip6t_SNPT");
- MODULE_ALIAS("ip6t_DNPT");
|