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@marasytems.com>");
  29 MODULE_DESCRIPTION("IP tables connmark match module");
  30 MODULE_LICENSE("GPL");
  31 MODULE_ALIAS("ipt_connmark");
  32
  33 static bool
  34 match(const struct sk_buff *skb,
  35       const struct net_device *in,
  36       const struct net_device *out,
  37       const struct xt_match *match,
  38       const void *matchinfo,
  39       int offset,
  40       unsigned int protoff,
  41       bool *hotdrop)
  42 {
  43         const struct xt_connmark_info *info = matchinfo;
  44         const struct nf_conn *ct;
  45         enum ip_conntrack_info ctinfo;
  46
  47         ct = nf_ct_get(skb, &ctinfo);
  48         if (!ct)
  49                 return false;
  50
  51         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
  52 }
  53
  54 static bool
  55 checkentry(const char *tablename,
  56            const void *ip,
  57            const struct xt_match *match,
  58            void *matchinfo,
  59            unsigned int hook_mask)
  60 {
  61         const struct xt_connmark_info *cm = matchinfo;
  62
  63         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  64                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  65                 return false;
  66         }
  67         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
  68                 printk(KERN_WARNING "can't load conntrack support for "
  69                                     "proto=%d\n", match->family);
  70                 return false;
  71         }
  72         return true;
  73 }
  74
  75 static void
  76 destroy(const struct xt_match *match, void *matchinfo)
  77 {
  78         nf_ct_l3proto_module_put(match->family);
  79 }
  80
  81 #ifdef CONFIG_COMPAT
  82 struct compat_xt_connmark_info {
  83         compat_ulong_t  mark, mask;
  84         u_int8_t        invert;
  85         u_int8_t        __pad1;
  86         u_int16_t       __pad2;
  87 };
  88
  89 static void compat_from_user(void *dst, void *src)
  90 {
  91         const struct compat_xt_connmark_info *cm = src;
  92         struct xt_connmark_info m = {
  93                 .mark   = cm->mark,
  94                 .mask   = cm->mask,
  95                 .invert = cm->invert,
  96         };
  97         memcpy(dst, &m, sizeof(m));
  98 }
  99
 100 static int compat_to_user(void __user *dst, void *src)
 101 {
 102         const struct xt_connmark_info *m = src;
 103         struct compat_xt_connmark_info cm = {
 104                 .mark   = m->mark,
 105                 .mask   = m->mask,
 106                 .invert = m->invert,
 107         };
 108         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 109 }
 110 #endif /* CONFIG_COMPAT */
 111
 112 static struct xt_match xt_connmark_match[] __read_mostly = {
 113         {
 114                 .name           = "connmark",
 115                 .family         = AF_INET,
 116                 .checkentry     = checkentry,
 117                 .match          = match,
 118                 .destroy        = destroy,
 119                 .matchsize      = sizeof(struct xt_connmark_info),
 120 #ifdef CONFIG_COMPAT
 121                 .compatsize     = sizeof(struct compat_xt_connmark_info),
 122                 .compat_from_user = compat_from_user,
 123                 .compat_to_user = compat_to_user,
 124 #endif
 125                 .me             = THIS_MODULE
 126         },
 127         {
 128                 .name           = "connmark",
 129                 .family         = AF_INET6,
 130                 .checkentry     = checkentry,
 131                 .match          = match,
 132                 .destroy        = destroy,
 133                 .matchsize      = sizeof(struct xt_connmark_info),
 134                 .me             = THIS_MODULE
 135         },
 136 };
 137
 138 static int __init xt_connmark_init(void)
 139 {
 140         return xt_register_matches(xt_connmark_match,
 141                                    ARRAY_SIZE(xt_connmark_match));
 142 }
 143
 144 static void __exit xt_connmark_fini(void)
 145 {
 146         xt_unregister_matches(xt_connmark_match, ARRAY_SIZE(xt_connmark_match));
 147 }
 148
 149 module_init(xt_connmark_init);
 150 module_exit(xt_connmark_fini);