net/netfilter/xt_comment.c

   1 /*
   2  * Implements a dummy match to allow attaching comments to rules
   3  *
   4  * 2003-05-13 Brad Fisher (brad@info-link.net)
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/skbuff.h>
   9 #include <linux/netfilter/x_tables.h>
  10 #include <linux/netfilter/xt_comment.h>
  11
  12 MODULE_AUTHOR("Brad Fisher <brad@info-link.net>");
  13 MODULE_DESCRIPTION("iptables comment match module");
  14 MODULE_LICENSE("GPL");
  15 MODULE_ALIAS("ipt_comment");
  16 MODULE_ALIAS("ip6t_comment");
  17
  18 static int
  19 match(const struct sk_buff *skb,
  20       const struct net_device *in,
  21       const struct net_device *out,
  22       const void *matchinfo,
  23       int offset,
  24       unsigned int protooff,
  25       int *hotdrop)
  26 {
  27         /* We always match */
  28         return 1;
  29 }
  30
  31 static int
  32 checkentry(const char *tablename,
  33            const void *ip,
  34            void *matchinfo,
  35            unsigned int matchsize,
  36            unsigned int hook_mask)
  37 {
  38         /* Check the size */
  39         if (matchsize != XT_ALIGN(sizeof(struct xt_comment_info)))
  40                 return 0;
  41         return 1;
  42 }
  43
  44 static struct xt_match comment_match = {
  45         .name           = "comment",
  46         .match          = match,
  47         .checkentry     = checkentry,
  48         .me             = THIS_MODULE
  49 };
  50
  51 static struct xt_match comment6_match = {
  52         .name           = "comment",
  53         .match          = match,
  54         .checkentry     = checkentry,
  55         .me             = THIS_MODULE
  56 };
  57
  58 static int __init init(void)
  59 {
  60         int ret;
  61
  62         ret = xt_register_match(AF_INET, &comment_match);
  63         if (ret)
  64                 return ret;
  65
  66         ret = xt_register_match(AF_INET6, &comment6_match);
  67         if (ret)
  68                 xt_unregister_match(AF_INET, &comment_match);
  69
  70         return ret;
  71 }
  72
  73 static void __exit fini(void)
  74 {
  75         xt_unregister_match(AF_INET, &comment_match);
  76         xt_unregister_match(AF_INET6, &comment6_match);
  77 }
  78
  79 module_init(init);
  80 module_exit(fini);