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 int __net_init ip6table_mangle_table_init(struct net *net);
  24
  25static const struct xt_table packet_mangler = {
  26        .name           = "mangle",
  27        .valid_hooks    = MANGLE_VALID_HOOKS,
  28        .me             = THIS_MODULE,
  29        .af             = NFPROTO_IPV6,
  30        .priority       = NF_IP6_PRI_MANGLE,
  31        .table_init     = ip6table_mangle_table_init,
  32};
  33
  34static unsigned int
  35ip6t_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
  36{
  37        unsigned int ret;
  38        struct in6_addr saddr, daddr;
  39        u_int8_t hop_limit;
  40        u_int32_t flowlabel, mark;
  41        int err;
  42
  43        /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
  44        memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
  45        memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
  46        mark = skb->mark;
  47        hop_limit = ipv6_hdr(skb)->hop_limit;
  48
  49        /* flowlabel and prio (includes version, which shouldn't change either */
  50        flowlabel = *((u_int32_t *)ipv6_hdr(skb));
  51
  52        ret = ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
  53
  54        if (ret != NF_DROP && ret != NF_STOLEN &&
  55            (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
  56             !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
  57             skb->mark != mark ||
  58             ipv6_hdr(skb)->hop_limit != hop_limit ||
  59             flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
  60                err = ip6_route_me_harder(state->net, skb);
  61                if (err < 0)
  62                        ret = NF_DROP_ERR(err);
  63        }
  64
  65        return ret;
  66}
  67
  68/* The work comes in here from netfilter.c. */
  69static unsigned int
  70ip6table_mangle_hook(void *priv, struct sk_buff *skb,
  71                     const struct nf_hook_state *state)
  72{
  73        if (state->hook == NF_INET_LOCAL_OUT)
  74                return ip6t_mangle_out(skb, state);
  75        return ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
  76}
  77
  78static struct nf_hook_ops *mangle_ops __read_mostly;
  79static int __net_init ip6table_mangle_table_init(struct net *net)
  80{
  81        struct ip6t_replace *repl;
  82        int ret;
  83
  84        if (net->ipv6.ip6table_mangle)
  85                return 0;
  86
  87        repl = ip6t_alloc_initial_table(&packet_mangler);
  88        if (repl == NULL)
  89                return -ENOMEM;
  90        ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops,
  91                                  &net->ipv6.ip6table_mangle);
  92        kfree(repl);
  93        return ret;
  94}
  95
  96static void __net_exit ip6table_mangle_net_exit(struct net *net)
  97{
  98        if (!net->ipv6.ip6table_mangle)
  99                return;
 100
 101        ip6t_unregister_table(net, net->ipv6.ip6table_mangle, mangle_ops);
 102        net->ipv6.ip6table_mangle = NULL;
 103}
 104
 105static struct pernet_operations ip6table_mangle_net_ops = {
 106        .exit = ip6table_mangle_net_exit,
 107};
 108
 109static int __init ip6table_mangle_init(void)
 110{
 111        int ret;
 112
 113        mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
 114        if (IS_ERR(mangle_ops))
 115                return PTR_ERR(mangle_ops);
 116
 117        ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 118        if (ret < 0) {
 119                kfree(mangle_ops);
 120                return ret;
 121        }
 122
 123        ret = ip6table_mangle_table_init(&init_net);
 124        if (ret) {
 125                unregister_pernet_subsys(&ip6table_mangle_net_ops);
 126                kfree(mangle_ops);
 127        }
 128        return ret;
 129}
 130
 131static void __exit ip6table_mangle_fini(void)
 132{
 133        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 134        kfree(mangle_ops);
 135}
 136
 137module_init(ip6table_mangle_init);
 138module_exit(ip6table_mangle_fini);
 139