net/ipv4/netfilter/iptable_raw.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * 'raw' table, which is the very first hooked in at PRE_ROUTING and LOCAL_OUT .
   4  *
   5  * Copyright (C) 2003 Jozsef Kadlecsik <kadlec@netfilter.org>
   6  */
   7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8 #include <linux/module.h>
   9 #include <linux/netfilter_ipv4/ip_tables.h>
  10 #include <linux/slab.h>
  11 #include <net/ip.h>
  12
  13 #define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))
  14
  15 static int __net_init iptable_raw_table_init(struct net *net);
  16
  17 static bool raw_before_defrag __read_mostly;
  18 MODULE_PARM_DESC(raw_before_defrag, "Enable raw table before defrag");
  19 module_param(raw_before_defrag, bool, 0000);
  20
  21 static const struct xt_table packet_raw = {
  22         .name = "raw",
  23         .valid_hooks =  RAW_VALID_HOOKS,
  24         .me = THIS_MODULE,
  25         .af = NFPROTO_IPV4,
  26         .priority = NF_IP_PRI_RAW,
  27         .table_init = iptable_raw_table_init,
  28 };
  29
  30 static const struct xt_table packet_raw_before_defrag = {
  31         .name = "raw",
  32         .valid_hooks =  RAW_VALID_HOOKS,
  33         .me = THIS_MODULE,
  34         .af = NFPROTO_IPV4,
  35         .priority = NF_IP_PRI_RAW_BEFORE_DEFRAG,
  36         .table_init = iptable_raw_table_init,
  37 };
  38
  39 /* The work comes in here from netfilter.c. */
  40 static unsigned int
  41 iptable_raw_hook(void *priv, struct sk_buff *skb,
  42                  const struct nf_hook_state *state)
  43 {
  44         return ipt_do_table(skb, state, state->net->ipv4.iptable_raw);
  45 }
  46
  47 static struct nf_hook_ops *rawtable_ops __read_mostly;
  48
  49 static int __net_init iptable_raw_table_init(struct net *net)
  50 {
  51         struct ipt_replace *repl;
  52         const struct xt_table *table = &packet_raw;
  53         int ret;
  54
  55         if (raw_before_defrag)
  56                 table = &packet_raw_before_defrag;
  57
  58         if (net->ipv4.iptable_raw)
  59                 return 0;
  60
  61         repl = ipt_alloc_initial_table(table);
  62         if (repl == NULL)
  63                 return -ENOMEM;
  64         ret = ipt_register_table(net, table, repl, rawtable_ops,
  65                                  &net->ipv4.iptable_raw);
  66         kfree(repl);
  67         return ret;
  68 }
  69
  70 static void __net_exit iptable_raw_net_pre_exit(struct net *net)
  71 {
  72         if (net->ipv4.iptable_raw)
  73                 ipt_unregister_table_pre_exit(net, net->ipv4.iptable_raw,
  74                                               rawtable_ops);
  75 }
  76
  77 static void __net_exit iptable_raw_net_exit(struct net *net)
  78 {
  79         if (!net->ipv4.iptable_raw)
  80                 return;
  81         ipt_unregister_table_exit(net, net->ipv4.iptable_raw);
  82         net->ipv4.iptable_raw = NULL;
  83 }
  84
  85 static struct pernet_operations iptable_raw_net_ops = {
  86         .pre_exit = iptable_raw_net_pre_exit,
  87         .exit = iptable_raw_net_exit,
  88 };
  89
  90 static int __init iptable_raw_init(void)
  91 {
  92         int ret;
  93         const struct xt_table *table = &packet_raw;
  94
  95         if (raw_before_defrag) {
  96                 table = &packet_raw_before_defrag;
  97
  98                 pr_info("Enabling raw table before defrag\n");
  99         }
 100
 101         rawtable_ops = xt_hook_ops_alloc(table, iptable_raw_hook);
 102         if (IS_ERR(rawtable_ops))
 103                 return PTR_ERR(rawtable_ops);
 104
 105         ret = register_pernet_subsys(&iptable_raw_net_ops);
 106         if (ret < 0) {
 107                 kfree(rawtable_ops);
 108                 return ret;
 109         }
 110
 111         ret = iptable_raw_table_init(&init_net);
 112         if (ret) {
 113                 unregister_pernet_subsys(&iptable_raw_net_ops);
 114                 kfree(rawtable_ops);
 115         }
 116
 117         return ret;
 118 }
 119
 120 static void __exit iptable_raw_fini(void)
 121 {
 122         unregister_pernet_subsys(&iptable_raw_net_ops);
 123         kfree(rawtable_ops);
 124 }
 125
 126 module_init(iptable_raw_init);
 127 module_exit(iptable_raw_fini);
 128 MODULE_LICENSE("GPL");