LXR linux/net/ipv6/netfilter/ip6table

   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(struct sk_buff *skb, const struct nf_hook_state *state, void *priv)
  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(skb, state, priv);
  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. */
  66static unsigned int
  67ip6table_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(skb, state, priv);
  72        return ip6t_do_table(skb, state, priv);
  73}
  74
  75static struct nf_hook_ops *mangle_ops __read_mostly;
  76static 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
  89static void __net_exit ip6table_mangle_net_pre_exit(struct net *net)
  90{
  91        ip6t_unregister_table_pre_exit(net, "mangle");
  92}
  93
  94static void __net_exit ip6table_mangle_net_exit(struct net *net)
  95{
  96        ip6t_unregister_table_exit(net, "mangle");
  97}
  98
  99static struct pernet_operations ip6table_mangle_net_ops = {
 100        .pre_exit = ip6table_mangle_net_pre_exit,
 101        .exit = ip6table_mangle_net_exit,
 102};
 103
 104static 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
 128static 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
 135module_init(ip6table_mangle_init);
 136module_exit(ip6table_mangle_fini);
 137