net/netfilter/xt_connmark.c

   1 /* This kernel module matches connection mark values set by the
   2  * CONNMARK target
   3  *
   4  * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
   5  * by Henrik Nordstrom <hno@marasystems.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/skbuff.h>
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <linux/netfilter/x_tables.h>
  26 #include <linux/netfilter/xt_connmark.h>
  27
  28 MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
  29 MODULE_DESCRIPTION("IP tables connmark match module");
  30 MODULE_LICENSE("GPL");
  31 MODULE_ALIAS("ipt_connmark");
  32 MODULE_ALIAS("ip6t_connmark");
  33
  34 static bool
  35 connmark_mt(const struct sk_buff *skb, const struct net_device *in,
  36             const struct net_device *out, const struct xt_match *match,
  37             const void *matchinfo, int offset, unsigned int protoff,
  38             bool *hotdrop)
  39 {
  40         const struct xt_connmark_info *info = matchinfo;
  41         const struct nf_conn *ct;
  42         enum ip_conntrack_info ctinfo;
  43
  44         ct = nf_ct_get(skb, &ctinfo);
  45         if (!ct)
  46                 return false;
  47
  48         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
  49 }
  50
  51 static bool
  52 connmark_mt_check(const char *tablename, const void *ip,
  53                   const struct xt_match *match, void *matchinfo,
  54                   unsigned int hook_mask)
  55 {
  56         const struct xt_connmark_info *cm = matchinfo;
  57
  58         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  59                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  60                 return false;
  61         }
  62         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
  63                 printk(KERN_WARNING "can't load conntrack support for "
  64                                     "proto=%d\n", match->family);
  65                 return false;
  66         }
  67         return true;
  68 }
  69
  70 static void
  71 connmark_mt_destroy(const struct xt_match *match, void *matchinfo)
  72 {
  73         nf_ct_l3proto_module_put(match->family);
  74 }
  75
  76 #ifdef CONFIG_COMPAT
  77 struct compat_xt_connmark_info {
  78         compat_ulong_t  mark, mask;
  79         u_int8_t        invert;
  80         u_int8_t        __pad1;
  81         u_int16_t       __pad2;
  82 };
  83
  84 static void connmark_mt_compat_from_user(void *dst, void *src)
  85 {
  86         const struct compat_xt_connmark_info *cm = src;
  87         struct xt_connmark_info m = {
  88                 .mark   = cm->mark,
  89                 .mask   = cm->mask,
  90                 .invert = cm->invert,
  91         };
  92         memcpy(dst, &m, sizeof(m));
  93 }
  94
  95 static int connmark_mt_compat_to_user(void __user *dst, void *src)
  96 {
  97         const struct xt_connmark_info *m = src;
  98         struct compat_xt_connmark_info cm = {
  99                 .mark   = m->mark,
 100                 .mask   = m->mask,
 101                 .invert = m->invert,
 102         };
 103         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 104 }
 105 #endif /* CONFIG_COMPAT */
 106
 107 static struct xt_match connmark_mt_reg[] __read_mostly = {
 108         {
 109                 .name           = "connmark",
 110                 .family         = AF_INET,
 111                 .checkentry     = connmark_mt_check,
 112                 .match          = connmark_mt,
 113                 .destroy        = connmark_mt_destroy,
 114                 .matchsize      = sizeof(struct xt_connmark_info),
 115 #ifdef CONFIG_COMPAT
 116                 .compatsize     = sizeof(struct compat_xt_connmark_info),
 117                 .compat_from_user = connmark_mt_compat_from_user,
 118                 .compat_to_user = connmark_mt_compat_to_user,
 119 #endif
 120                 .me             = THIS_MODULE
 121         },
 122         {
 123                 .name           = "connmark",
 124                 .family         = AF_INET6,
 125                 .checkentry     = connmark_mt_check,
 126                 .match          = connmark_mt,
 127                 .destroy        = connmark_mt_destroy,
 128                 .matchsize      = sizeof(struct xt_connmark_info),
 129                 .me             = THIS_MODULE
 130         },
 131 };
 132
 133 static int __init connmark_mt_init(void)
 134 {
 135         return xt_register_matches(connmark_mt_reg,
 136                ARRAY_SIZE(connmark_mt_reg));
 137 }
 138
 139 static void __exit connmark_mt_exit(void)
 140 {
 141         xt_unregister_matches(connmark_mt_reg, ARRAY_SIZE(connmark_mt_reg));
 142 }
 143
 144 module_init(connmark_mt_init);
 145 module_exit(connmark_mt_exit);