1 /* 2 * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6 3 * 4 * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> 5 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #include <linux/module.h> 12 #include <linux/netfilter_ipv6/ip6_tables.h> 13 #include <linux/slab.h> 14 #include <net/ipv6.h> 15 16 MODULE_LICENSE("GPL"); 17 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 18 MODULE_DESCRIPTION("ip6tables mangle table"); 19 20 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ 21 (1 << NF_INET_LOCAL_IN) | \ 22 (1 << NF_INET_FORWARD) | \ 23 (1 << NF_INET_LOCAL_OUT) | \ 24 (1 << NF_INET_POST_ROUTING)) 25 26 static int __net_init ip6table_mangle_table_init(struct net *net); 27 28 static const struct xt_table packet_mangler = { 29 .name = "mangle", 30 .valid_hooks = MANGLE_VALID_HOOKS, 31 .me = THIS_MODULE, 32 .af = NFPROTO_IPV6, 33 .priority = NF_IP6_PRI_MANGLE, 34 .table_init = ip6table_mangle_table_init, 35 }; 36 37 static unsigned int 38 ip6t_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state) 39 { 40 unsigned int ret; 41 struct in6_addr saddr, daddr; 42 u_int8_t hop_limit; 43 u_int32_t flowlabel, mark; 44 int err; 45 #if 0 46 /* root is playing with raw sockets. */ 47 if (skb->len < sizeof(struct iphdr) || 48 ip_hdrlen(skb) < sizeof(struct iphdr)) { 49 net_warn_ratelimited("ip6t_hook: happy cracking\n"); 50 return NF_ACCEPT; 51 } 52 #endif 53 54 /* save source/dest address, mark, hoplimit, flowlabel, priority, */ 55 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr)); 56 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr)); 57 mark = skb->mark; 58 hop_limit = ipv6_hdr(skb)->hop_limit; 59 60 /* flowlabel and prio (includes version, which shouldn't change either */ 61 flowlabel = *((u_int32_t *)ipv6_hdr(skb)); 62 63 ret = ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle); 64 65 if (ret != NF_DROP && ret != NF_STOLEN && 66 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) || 67 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) || 68 skb->mark != mark || 69 ipv6_hdr(skb)->hop_limit != hop_limit || 70 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) { 71 err = ip6_route_me_harder(state->net, skb); 72 if (err < 0) 73 ret = NF_DROP_ERR(err); 74 } 75 76 return ret; 77 } 78 79 /* The work comes in here from netfilter.c. */ 80 static unsigned int 81 ip6table_mangle_hook(void *priv, struct sk_buff *skb, 82 const struct nf_hook_state *state) 83 { 84 if (state->hook == NF_INET_LOCAL_OUT) 85 return ip6t_mangle_out(skb, state); 86 if (state->hook == NF_INET_POST_ROUTING) 87 return ip6t_do_table(skb, state, 88 state->net->ipv6.ip6table_mangle); 89 /* INPUT/FORWARD */ 90 return ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle); 91 } 92 93 static struct nf_hook_ops *mangle_ops __read_mostly; 94 static int __net_init ip6table_mangle_table_init(struct net *net) 95 { 96 struct ip6t_replace *repl; 97 int ret; 98 99 if (net->ipv6.ip6table_mangle) 100 return 0; 101 102 repl = ip6t_alloc_initial_table(&packet_mangler); 103 if (repl == NULL) 104 return -ENOMEM; 105 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops, 106 &net->ipv6.ip6table_mangle); 107 kfree(repl); 108 return ret; 109 } 110 111 static void __net_exit ip6table_mangle_net_exit(struct net *net) 112 { 113 if (!net->ipv6.ip6table_mangle) 114 return; 115 116 ip6t_unregister_table(net, net->ipv6.ip6table_mangle, mangle_ops); 117 net->ipv6.ip6table_mangle = NULL; 118 } 119 120 static struct pernet_operations ip6table_mangle_net_ops = { 121 .exit = ip6table_mangle_net_exit, 122 }; 123 124 static int __init ip6table_mangle_init(void) 125 { 126 int ret; 127 128 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook); 129 if (IS_ERR(mangle_ops)) 130 return PTR_ERR(mangle_ops); 131 132 ret = register_pernet_subsys(&ip6table_mangle_net_ops); 133 if (ret < 0) { 134 kfree(mangle_ops); 135 return ret; 136 } 137 138 ret = ip6table_mangle_table_init(&init_net); 139 if (ret) { 140 unregister_pernet_subsys(&ip6table_mangle_net_ops); 141 kfree(mangle_ops); 142 } 143 return ret; 144 } 145 146 static void __exit ip6table_mangle_fini(void) 147 { 148 unregister_pernet_subsys(&ip6table_mangle_net_ops); 149 kfree(mangle_ops); 150 } 151 152 module_init(ip6table_mangle_init); 153 module_exit(ip6table_mangle_fini); 154