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
  25 MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
  26 MODULE_DESCRIPTION("IP tables connmark match module");
  27 MODULE_LICENSE("GPL");
  28 MODULE_ALIAS("ipt_connmark");
  29
  30 #include <linux/netfilter/x_tables.h>
  31 #include <linux/netfilter/xt_connmark.h>
  32 #include <net/netfilter/nf_conntrack_compat.h>
  33
  34 static int
  35 match(const struct sk_buff *skb,
  36       const struct net_device *in,
  37       const struct net_device *out,
  38       const struct xt_match *match,
  39       const void *matchinfo,
  40       int offset,
  41       unsigned int protoff,
  42       int *hotdrop)
  43 {
  44         const struct xt_connmark_info *info = matchinfo;
  45         u_int32_t ctinfo;
  46         const u_int32_t *ctmark = nf_ct_get_mark(skb, &ctinfo);
  47         if (!ctmark)
  48                 return 0;
  49
  50         return (((*ctmark) & info->mask) == info->mark) ^ info->invert;
  51 }
  52
  53 static int
  54 checkentry(const char *tablename,
  55            const void *ip,
  56            const struct xt_match *match,
  57            void *matchinfo,
  58            unsigned int hook_mask)
  59 {
  60         struct xt_connmark_info *cm = matchinfo;
  61
  62         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  63                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  64                 return 0;
  65         }
  66 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  67         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
  68                 printk(KERN_WARNING "can't load nf_conntrack support for "
  69                                     "proto=%d\n", match->family);
  70                 return 0;
  71         }
  72 #endif
  73         return 1;
  74 }
  75
  76 static void
  77 destroy(const struct xt_match *match, void *matchinfo)
  78 {
  79 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  80         nf_ct_l3proto_module_put(match->family);
  81 #endif
  82 }
  83
  84 #ifdef CONFIG_COMPAT
  85 struct compat_xt_connmark_info {
  86         compat_ulong_t  mark, mask;
  87         u_int8_t        invert;
  88         u_int8_t        __pad1;
  89         u_int16_t       __pad2;
  90 };
  91
  92 static void compat_from_user(void *dst, void *src)
  93 {
  94         struct compat_xt_connmark_info *cm = src;
  95         struct xt_connmark_info m = {
  96                 .mark   = cm->mark,
  97                 .mask   = cm->mask,
  98                 .invert = cm->invert,
  99         };
 100         memcpy(dst, &m, sizeof(m));
 101 }
 102
 103 static int compat_to_user(void __user *dst, void *src)
 104 {
 105         struct xt_connmark_info *m = src;
 106         struct compat_xt_connmark_info cm = {
 107                 .mark   = m->mark,
 108                 .mask   = m->mask,
 109                 .invert = m->invert,
 110         };
 111         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 112 }
 113 #endif /* CONFIG_COMPAT */
 114
 115 static struct xt_match xt_connmark_match[] = {
 116         {
 117                 .name           = "connmark",
 118                 .family         = AF_INET,
 119                 .checkentry     = checkentry,
 120                 .match          = match,
 121                 .destroy        = destroy,
 122                 .matchsize      = sizeof(struct xt_connmark_info),
 123 #ifdef CONFIG_COMPAT
 124                 .compatsize     = sizeof(struct compat_xt_connmark_info),
 125                 .compat_from_user = compat_from_user,
 126                 .compat_to_user = compat_to_user,
 127 #endif
 128                 .me             = THIS_MODULE
 129         },
 130         {
 131                 .name           = "connmark",
 132                 .family         = AF_INET6,
 133                 .checkentry     = checkentry,
 134                 .match          = match,
 135                 .destroy        = destroy,
 136                 .matchsize      = sizeof(struct xt_connmark_info),
 137                 .me             = THIS_MODULE
 138         },
 139 };
 140
 141 static int __init xt_connmark_init(void)
 142 {
 143         need_conntrack();
 144         return xt_register_matches(xt_connmark_match,
 145                                    ARRAY_SIZE(xt_connmark_match));
 146 }
 147
 148 static void __exit xt_connmark_fini(void)
 149 {
 150         xt_unregister_matches(xt_connmark_match, ARRAY_SIZE(xt_connmark_match));
 151 }
 152
 153 module_init(xt_connmark_init);
 154 module_exit(xt_connmark_fini);