net/ipv4/netfilter/iptable_security.c

   1 /*
   2  * "security" table
   3  *
   4  * This is for use by Mandatory Access Control (MAC) security models,
   5  * which need to be able to manage security policy in separate context
   6  * to DAC.
   7  *
   8  * Based on iptable_mangle.c
   9  *
  10  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
  11  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam <at> netfilter.org>
  12  * Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.com>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18 #include <linux/module.h>
  19 #include <linux/netfilter_ipv4/ip_tables.h>
  20 #include <net/ip.h>
  21
  22 MODULE_LICENSE("GPL");
  23 MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");
  24 MODULE_DESCRIPTION("iptables security table, for MAC rules");
  25
  26 #define SECURITY_VALID_HOOKS    (1 << NF_INET_LOCAL_IN) | \
  27                                 (1 << NF_INET_FORWARD) | \
  28                                 (1 << NF_INET_LOCAL_OUT)
  29
  30 static const struct
  31 {
  32         struct ipt_replace repl;
  33         struct ipt_standard entries[3];
  34         struct ipt_error term;
  35 } initial_table __net_initdata = {
  36         .repl = {
  37                 .name = "security",
  38                 .valid_hooks = SECURITY_VALID_HOOKS,
  39                 .num_entries = 4,
  40                 .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
  41                 .hook_entry = {
  42                         [NF_INET_LOCAL_IN]      = 0,
  43                         [NF_INET_FORWARD]       = sizeof(struct ipt_standard),
  44                         [NF_INET_LOCAL_OUT]     = sizeof(struct ipt_standard) * 2,
  45                 },
  46                 .underflow = {
  47                         [NF_INET_LOCAL_IN]      = 0,
  48                         [NF_INET_FORWARD]       = sizeof(struct ipt_standard),
  49                         [NF_INET_LOCAL_OUT]     = sizeof(struct ipt_standard) * 2,
  50                 },
  51         },
  52         .entries = {
  53                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_IN */
  54                 IPT_STANDARD_INIT(NF_ACCEPT),   /* FORWARD */
  55                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
  56         },
  57         .term = IPT_ERROR_INIT,                 /* ERROR */
  58 };
  59
  60 static const struct xt_table security_table = {
  61         .name           = "security",
  62         .valid_hooks    = SECURITY_VALID_HOOKS,
  63         .me             = THIS_MODULE,
  64         .af             = NFPROTO_IPV4,
  65 };
  66
  67 static unsigned int
  68 iptable_security_hook(unsigned int hook, struct sk_buff *skb,
  69                       const struct net_device *in,
  70                       const struct net_device *out,
  71                       int (*okfn)(struct sk_buff *))
  72 {
  73         const struct net *net;
  74
  75         if (hook == NF_INET_LOCAL_OUT &&
  76             (skb->len < sizeof(struct iphdr) ||
  77              ip_hdrlen(skb) < sizeof(struct iphdr)))
  78                 /* Somebody is playing with raw sockets. */
  79                 return NF_ACCEPT;
  80
  81         net = dev_net((in != NULL) ? in : out);
  82         return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_security);
  83 }
  84
  85 static struct nf_hook_ops ipt_ops[] __read_mostly = {
  86         {
  87                 .hook           = iptable_security_hook,
  88                 .owner          = THIS_MODULE,
  89                 .pf             = NFPROTO_IPV4,
  90                 .hooknum        = NF_INET_LOCAL_IN,
  91                 .priority       = NF_IP_PRI_SECURITY,
  92         },
  93         {
  94                 .hook           = iptable_security_hook,
  95                 .owner          = THIS_MODULE,
  96                 .pf             = NFPROTO_IPV4,
  97                 .hooknum        = NF_INET_FORWARD,
  98                 .priority       = NF_IP_PRI_SECURITY,
  99         },
 100         {
 101                 .hook           = iptable_security_hook,
 102                 .owner          = THIS_MODULE,
 103                 .pf             = NFPROTO_IPV4,
 104                 .hooknum        = NF_INET_LOCAL_OUT,
 105                 .priority       = NF_IP_PRI_SECURITY,
 106         },
 107 };
 108
 109 static int __net_init iptable_security_net_init(struct net *net)
 110 {
 111         net->ipv4.iptable_security =
 112                 ipt_register_table(net, &security_table, &initial_table.repl);
 113
 114         if (IS_ERR(net->ipv4.iptable_security))
 115                 return PTR_ERR(net->ipv4.iptable_security);
 116
 117         return 0;
 118 }
 119
 120 static void __net_exit iptable_security_net_exit(struct net *net)
 121 {
 122         ipt_unregister_table(net, net->ipv4.iptable_security);
 123 }
 124
 125 static struct pernet_operations iptable_security_net_ops = {
 126         .init = iptable_security_net_init,
 127         .exit = iptable_security_net_exit,
 128 };
 129
 130 static int __init iptable_security_init(void)
 131 {
 132         int ret;
 133
 134         ret = register_pernet_subsys(&iptable_security_net_ops);
 135         if (ret < 0)
 136                 return ret;
 137
 138         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 139         if (ret < 0)
 140                 goto cleanup_table;
 141
 142         return ret;
 143
 144 cleanup_table:
 145         unregister_pernet_subsys(&iptable_security_net_ops);
 146         return ret;
 147 }
 148
 149 static void __exit iptable_security_fini(void)
 150 {
 151         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 152         unregister_pernet_subsys(&iptable_security_net_ops);
 153 }
 154
 155 module_init(iptable_security_init);
 156 module_exit(iptable_security_fini);