1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * (C) 1999-2001 Paul `Rusty' Russell 4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 5 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net> 6 * 7 * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6 8 * NAT funded by Astaro. 9 */ 10 11 #include <linux/if.h> 12 #include <linux/inetdevice.h> 13 #include <linux/ip.h> 14 #include <linux/kernel.h> 15 #include <linux/netdevice.h> 16 #include <linux/netfilter.h> 17 #include <linux/types.h> 18 #include <linux/netfilter_ipv4.h> 19 #include <linux/netfilter_ipv6.h> 20 #include <linux/netfilter/x_tables.h> 21 #include <net/addrconf.h> 22 #include <net/checksum.h> 23 #include <net/protocol.h> 24 #include <net/netfilter/nf_nat.h> 25 #include <net/netfilter/nf_nat_redirect.h> 26 27 unsigned int 28 nf_nat_redirect_ipv4(struct sk_buff *skb, 29 const struct nf_nat_ipv4_multi_range_compat *mr, 30 unsigned int hooknum) 31 { 32 struct nf_conn *ct; 33 enum ip_conntrack_info ctinfo; 34 __be32 newdst; 35 struct nf_nat_range2 newrange; 36 37 WARN_ON(hooknum != NF_INET_PRE_ROUTING && 38 hooknum != NF_INET_LOCAL_OUT); 39 40 ct = nf_ct_get(skb, &ctinfo); 41 WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED))); 42 43 /* Local packets: make them go to loopback */ 44 if (hooknum == NF_INET_LOCAL_OUT) { 45 newdst = htonl(0x7F000001); 46 } else { 47 const struct in_device *indev; 48 49 newdst = 0; 50 51 indev = __in_dev_get_rcu(skb->dev); 52 if (indev) { 53 const struct in_ifaddr *ifa; 54 55 ifa = rcu_dereference(indev->ifa_list); 56 if (ifa) 57 newdst = ifa->ifa_local; 58 } 59 60 if (!newdst) 61 return NF_DROP; 62 } 63 64 /* Transfer from original range. */ 65 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); 66 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); 67 newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS; 68 newrange.min_addr.ip = newdst; 69 newrange.max_addr.ip = newdst; 70 newrange.min_proto = mr->range[0].min; 71 newrange.max_proto = mr->range[0].max; 72 73 /* Hand modified range to generic setup. */ 74 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); 75 } 76 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4); 77 78 static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT; 79 80 unsigned int 81 nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range, 82 unsigned int hooknum) 83 { 84 struct nf_nat_range2 newrange; 85 struct in6_addr newdst; 86 enum ip_conntrack_info ctinfo; 87 struct nf_conn *ct; 88 89 ct = nf_ct_get(skb, &ctinfo); 90 if (hooknum == NF_INET_LOCAL_OUT) { 91 newdst = loopback_addr; 92 } else { 93 struct inet6_dev *idev; 94 struct inet6_ifaddr *ifa; 95 bool addr = false; 96 97 idev = __in6_dev_get(skb->dev); 98 if (idev != NULL) { 99 read_lock_bh(&idev->lock); 100 list_for_each_entry(ifa, &idev->addr_list, if_list) { 101 newdst = ifa->addr; 102 addr = true; 103 break; 104 } 105 read_unlock_bh(&idev->lock); 106 } 107 108 if (!addr) 109 return NF_DROP; 110 } 111 112 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; 113 newrange.min_addr.in6 = newdst; 114 newrange.max_addr.in6 = newdst; 115 newrange.min_proto = range->min_proto; 116 newrange.max_proto = range->max_proto; 117 118 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); 119 } 120 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6); 121