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 13 MODULE_LICENSE("GPL"); 14 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 15 MODULE_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 23 static 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 31 static unsigned int 32 ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) 33 { 34 unsigned int ret; 35 struct in6_addr saddr, daddr; 36 u_int8_t hop_limit; 37 u_int32_t flowlabel, mark; 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 51 if (ret != NF_DROP && ret != NF_STOLEN && 52 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) || 53 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) || 54 skb->mark != mark || 55 ipv6_hdr(skb)->hop_limit != hop_limit || 56 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) { 57 err = ip6_route_me_harder(state->net, state->sk, skb); 58 if (err < 0) 59 ret = NF_DROP_ERR(err); 60 } 61 62 return ret; 63 } 64 65 /* The work comes in here from netfilter.c. */ 66 static unsigned int 67 ip6table_mangle_hook(void *priv, struct sk_buff *skb, 68 const struct nf_hook_state *state) 69 { 70 if (state->hook == NF_INET_LOCAL_OUT) 71 return ip6t_mangle_out(priv, skb, state); 72 return ip6t_do_table(priv, skb, state); 73 } 74 75 static struct nf_hook_ops *mangle_ops __read_mostly; 76 static int ip6table_mangle_table_init(struct net *net) 77 { 78 struct ip6t_replace *repl; 79 int ret; 80 81 repl = ip6t_alloc_initial_table(&packet_mangler); 82 if (repl == NULL) 83 return -ENOMEM; 84 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops); 85 kfree(repl); 86 return ret; 87 } 88 89 static void __net_exit ip6table_mangle_net_pre_exit(struct net *net) 90 { 91 ip6t_unregister_table_pre_exit(net, "mangle"); 92 } 93 94 static void __net_exit ip6table_mangle_net_exit(struct net *net) 95 { 96 ip6t_unregister_table_exit(net, "mangle"); 97 } 98 99 static struct pernet_operations ip6table_mangle_net_ops = { 100 .pre_exit = ip6table_mangle_net_pre_exit, 101 .exit = ip6table_mangle_net_exit, 102 }; 103 104 static int __init ip6table_mangle_init(void) 105 { 106 int ret = xt_register_template(&packet_mangler, 107 ip6table_mangle_table_init); 108 109 if (ret < 0) 110 return ret; 111 112 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook); 113 if (IS_ERR(mangle_ops)) { 114 xt_unregister_template(&packet_mangler); 115 return PTR_ERR(mangle_ops); 116 } 117 118 ret = register_pernet_subsys(&ip6table_mangle_net_ops); 119 if (ret < 0) { 120 xt_unregister_template(&packet_mangler); 121 kfree(mangle_ops); 122 return ret; 123 } 124 125 return ret; 126 } 127 128 static void __exit ip6table_mangle_fini(void) 129 { 130 unregister_pernet_subsys(&ip6table_mangle_net_ops); 131 xt_unregister_template(&packet_mangler); 132 kfree(mangle_ops); 133 } 134 135 module_init(ip6table_mangle_init); 136 module_exit(ip6table_mangle_fini); 137