net/ipv4/netfilter/iptable_security.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * "security" table
   4  *
   5  * This is for use by Mandatory Access Control (MAC) security models,
   6  * which need to be able to manage security policy in separate context
   7  * to DAC.
   8  *
   9  * Based on iptable_mangle.c
  10  *
  11  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
  12  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam <at> netfilter.org>
  13  * Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.com>
  14  */
  15 #include <linux/module.h>
  16 #include <linux/netfilter_ipv4/ip_tables.h>
  17 #include <linux/slab.h>
  18 #include <net/ip.h>
  19
  20 MODULE_LICENSE("GPL");
  21 MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");
  22 MODULE_DESCRIPTION("iptables security table, for MAC rules");
  23
  24 #define SECURITY_VALID_HOOKS    (1 << NF_INET_LOCAL_IN) | \
  25                                 (1 << NF_INET_FORWARD) | \
  26                                 (1 << NF_INET_LOCAL_OUT)
  27
  28 static int __net_init iptable_security_table_init(struct net *net);
  29
  30 static const struct xt_table security_table = {
  31         .name           = "security",
  32         .valid_hooks    = SECURITY_VALID_HOOKS,
  33         .me             = THIS_MODULE,
  34         .af             = NFPROTO_IPV4,
  35         .priority       = NF_IP_PRI_SECURITY,
  36         .table_init     = iptable_security_table_init,
  37 };
  38
  39 static unsigned int
  40 iptable_security_hook(void *priv, struct sk_buff *skb,
  41                       const struct nf_hook_state *state)
  42 {
  43         return ipt_do_table(skb, state, state->net->ipv4.iptable_security);
  44 }
  45
  46 static struct nf_hook_ops *sectbl_ops __read_mostly;
  47
  48 static int __net_init iptable_security_table_init(struct net *net)
  49 {
  50         struct ipt_replace *repl;
  51         int ret;
  52
  53         if (net->ipv4.iptable_security)
  54                 return 0;
  55
  56         repl = ipt_alloc_initial_table(&security_table);
  57         if (repl == NULL)
  58                 return -ENOMEM;
  59         ret = ipt_register_table(net, &security_table, repl, sectbl_ops,
  60                                  &net->ipv4.iptable_security);
  61         kfree(repl);
  62         return ret;
  63 }
  64
  65 static void __net_exit iptable_security_net_pre_exit(struct net *net)
  66 {
  67         if (net->ipv4.iptable_security)
  68                 ipt_unregister_table_pre_exit(net, net->ipv4.iptable_security,
  69                                               sectbl_ops);
  70 }
  71
  72 static void __net_exit iptable_security_net_exit(struct net *net)
  73 {
  74         if (!net->ipv4.iptable_security)
  75                 return;
  76         ipt_unregister_table_exit(net, net->ipv4.iptable_security);
  77         net->ipv4.iptable_security = NULL;
  78 }
  79
  80 static struct pernet_operations iptable_security_net_ops = {
  81         .pre_exit = iptable_security_net_pre_exit,
  82         .exit = iptable_security_net_exit,
  83 };
  84
  85 static int __init iptable_security_init(void)
  86 {
  87         int ret;
  88
  89         sectbl_ops = xt_hook_ops_alloc(&security_table, iptable_security_hook);
  90         if (IS_ERR(sectbl_ops))
  91                 return PTR_ERR(sectbl_ops);
  92
  93         ret = register_pernet_subsys(&iptable_security_net_ops);
  94         if (ret < 0) {
  95                 kfree(sectbl_ops);
  96                 return ret;
  97         }
  98
  99         ret = iptable_security_table_init(&init_net);
 100         if (ret) {
 101                 unregister_pernet_subsys(&iptable_security_net_ops);
 102                 kfree(sectbl_ops);
 103         }
 104
 105         return ret;
 106 }
 107
 108 static void __exit iptable_security_fini(void)
 109 {
 110         unregister_pernet_subsys(&iptable_security_net_ops);
 111         kfree(sectbl_ops);
 112 }
 113
 114 module_init(iptable_security_init);
 115 module_exit(iptable_security_fini);