1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6 4 * 5 * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> 6 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> 7 */ 8#include <linux/module.h> 9#include <linux/netfilter_ipv6/ip6_tables.h> 10#include <linux/slab.h> 11#include <net/ipv6.h> 12 13MODULE_LICENSE("GPL"); 14MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 15MODULE_DESCRIPTION("ip6tables mangle table"); 16 17#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ 18 (1 << NF_INET_LOCAL_IN) | \ 19 (1 << NF_INET_FORWARD) | \ 20 (1 << NF_INET_LOCAL_OUT) | \ 21 (1 << NF_INET_POST_ROUTING)) 22 23static const struct xt_table packet_mangler = { 24 .name = "mangle", 25 .valid_hooks = MANGLE_VALID_HOOKS, 26 .me = THIS_MODULE, 27 .af = NFPROTO_IPV6, 28 .priority = NF_IP6_PRI_MANGLE, 29}; 30 31static unsigned int 32ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) 33{ 34 struct in6_addr saddr, daddr; 35 unsigned int ret, verdict; 36 u32 flowlabel, mark; 37 u8 hop_limit; 38 int err; 39 40 /* save source/dest address, mark, hoplimit, flowlabel, priority, */ 41 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr)); 42 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr)); 43 mark = skb->mark; 44 hop_limit = ipv6_hdr(skb)->hop_limit; 45 46 /* flowlabel and prio (includes version, which shouldn't change either */ 47 flowlabel = *((u_int32_t *)ipv6_hdr(skb)); 48 49 ret = ip6t_do_table(priv, skb, state); 50 verdict = ret & NF_VERDICT_MASK; 51 52 if (verdict != NF_DROP && verdict != NF_STOLEN && 53 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) || 54 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) || 55 skb->mark != mark || 56 ipv6_hdr(skb)->hop_limit != hop_limit || 57 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) { 58 err = ip6_route_me_harder(state->net, state->sk, skb); 59 if (err < 0) 60 ret = NF_DROP_ERR(err); 61 } 62 63 return ret; 64} 65 66/* The work comes in here from netfilter.c. */ 67static unsigned int 68ip6table_mangle_hook(void *priv, struct sk_buff *skb, 69 const struct nf_hook_state *state) 70{ 71 if (state->hook == NF_INET_LOCAL_OUT) 72 return ip6t_mangle_out(priv, skb, state); 73 return ip6t_do_table(priv, skb, state); 74} 75 76static struct nf_hook_ops *mangle_ops __read_mostly; 77static int ip6table_mangle_table_init(struct net *net) 78{ 79 struct ip6t_replace *repl; 80 int ret; 81 82 repl = ip6t_alloc_initial_table(&packet_mangler); 83 if (repl == NULL) 84 return -ENOMEM; 85 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops); 86 kfree(repl); 87 return ret; 88} 89 90static void __net_exit ip6table_mangle_net_pre_exit(struct net *net) 91{ 92 ip6t_unregister_table_pre_exit(net, "mangle"); 93} 94 95static void __net_exit ip6table_mangle_net_exit(struct net *net) 96{ 97 ip6t_unregister_table_exit(net, "mangle"); 98} 99 100static struct pernet_operations ip6table_mangle_net_ops = { 101 .pre_exit = ip6table_mangle_net_pre_exit, 102 .exit = ip6table_mangle_net_exit, 103}; 104 105static int __init ip6table_mangle_init(void) 106{ 107 int ret = xt_register_template(&packet_mangler, 108 ip6table_mangle_table_init); 109 110 if (ret < 0) 111 return ret; 112 113 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook); 114 if (IS_ERR(mangle_ops)) { 115 xt_unregister_template(&packet_mangler); 116 return PTR_ERR(mangle_ops); 117 } 118 119 ret = register_pernet_subsys(&ip6table_mangle_net_ops); 120 if (ret < 0) { 121 xt_unregister_template(&packet_mangler); 122 kfree(mangle_ops); 123 return ret; 124 } 125 126 return ret; 127} 128 129static void __exit ip6table_mangle_fini(void) 130{ 131 unregister_pernet_subsys(&ip6table_mangle_net_ops); 132 xt_unregister_template(&packet_mangler); 133 kfree(mangle_ops); 134} 135 136module_init(ip6table_mangle_init); 137module_exit(ip6table_mangle_fini); 138