release/src-rt-6.x/linux/linux-2.6/net/netfilter/xt_CONNMARK.c

   1 /* This kernel module is used to modify the connection mark values, or
   2  * to optionally restore the skb nfmark from the connection mark
   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 #include <linux/module.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/ip.h>
  24 #include <net/checksum.h>
  25
  26 MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
  27 MODULE_DESCRIPTION("IP tables CONNMARK matching module");
  28 MODULE_LICENSE("GPL");
  29 MODULE_ALIAS("ipt_CONNMARK");
  30
  31 #include <linux/netfilter/x_tables.h>
  32 #include <linux/netfilter/xt_CONNMARK.h>
  33 #include <net/netfilter/nf_conntrack_ecache.h>
  34
  35 static unsigned int
  36 target(struct sk_buff *skb,
  37        const struct net_device *in,
  38        const struct net_device *out,
  39        unsigned int hooknum,
  40        const struct xt_target *target,
  41        const void *targinfo)
  42 {
  43         const struct xt_connmark_target_info *markinfo = targinfo;
  44         struct nf_conn *ct;
  45         enum ip_conntrack_info ctinfo;
  46         u_int32_t diff;
  47         u_int32_t mark;
  48         u_int32_t newmark;
  49
  50         ct = nf_ct_get(skb, &ctinfo);
  51         if (ct) {
  52                 switch(markinfo->mode) {
  53                 case XT_CONNMARK_SET:
  54                         newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
  55                         if (newmark != ct->mark) {
  56                                 ct->mark = newmark;
  57                                 nf_conntrack_event_cache(IPCT_MARK, skb);
  58                         }
  59                         break;
  60                 case XT_CONNMARK_SET_RETURN:
  61                         // Set connmark and mark, apply mask to mark, do XT_RETURN      - zzz
  62                         newmark = ct->mark = markinfo->mark;
  63                         newmark &= markinfo->mask;
  64                         mark = skb->mark;
  65                         if (newmark != mark) {
  66                                 skb->mark = newmark;
  67                         }
  68                         return XT_RETURN;
  69                 case XT_CONNMARK_SAVE:
  70                         newmark = (ct->mark & ~markinfo->mask) |
  71                                   (skb->mark & markinfo->mask);
  72                         if (ct->mark != newmark) {
  73                                 ct->mark = newmark;
  74                                 nf_conntrack_event_cache(IPCT_MARK, skb);
  75                         }
  76                         break;
  77                 case XT_CONNMARK_RESTORE:
  78                         mark = skb->mark;
  79                         diff = (ct->mark ^ mark) & markinfo->mask;
  80                         skb->mark = mark ^ diff;
  81                         break;
  82                 }
  83         }
  84
  85         return XT_CONTINUE;
  86 }
  87
  88 static int
  89 checkentry(const char *tablename,
  90            const void *entry,
  91            const struct xt_target *target,
  92            void *targinfo,
  93            unsigned int hook_mask)
  94 {
  95         struct xt_connmark_target_info *matchinfo = targinfo;
  96
  97         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
  98                 printk(KERN_WARNING "can't load conntrack support for "
  99                                     "proto=%d\n", target->family);
 100                 return 0;
 101         }
 102         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
 103                 if (strcmp(tablename, "mangle") != 0) {
 104                         printk(KERN_WARNING "CONNMARK: restore can only be "
 105                                "called from \"mangle\" table, not \"%s\"\n",
 106                                tablename);
 107                         return 0;
 108                 }
 109         }
 110         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 111                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 112                 return 0;
 113         }
 114         return 1;
 115 }
 116
 117 static void
 118 destroy(const struct xt_target *target, void *targinfo)
 119 {
 120         nf_ct_l3proto_module_put(target->family);
 121 }
 122
 123 #ifdef CONFIG_COMPAT
 124 struct compat_xt_connmark_target_info {
 125         compat_ulong_t  mark, mask;
 126         u_int8_t        mode;
 127         u_int8_t        __pad1;
 128         u_int16_t       __pad2;
 129 };
 130
 131 static void compat_from_user(void *dst, void *src)
 132 {
 133         struct compat_xt_connmark_target_info *cm = src;
 134         struct xt_connmark_target_info m = {
 135                 .mark   = cm->mark,
 136                 .mask   = cm->mask,
 137                 .mode   = cm->mode,
 138         };
 139         memcpy(dst, &m, sizeof(m));
 140 }
 141
 142 static int compat_to_user(void __user *dst, void *src)
 143 {
 144         struct xt_connmark_target_info *m = src;
 145         struct compat_xt_connmark_target_info cm = {
 146                 .mark   = m->mark,
 147                 .mask   = m->mask,
 148                 .mode   = m->mode,
 149         };
 150         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 151 }
 152 #endif /* CONFIG_COMPAT */
 153
 154 static struct xt_target xt_connmark_target[] = {
 155         {
 156                 .name           = "CONNMARK",
 157                 .family         = AF_INET,
 158                 .checkentry     = checkentry,
 159                 .destroy        = destroy,
 160                 .target         = target,
 161                 .targetsize     = sizeof(struct xt_connmark_target_info),
 162 #ifdef CONFIG_COMPAT
 163                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 164                 .compat_from_user = compat_from_user,
 165                 .compat_to_user = compat_to_user,
 166 #endif
 167                 .me             = THIS_MODULE
 168         },
 169         {
 170                 .name           = "CONNMARK",
 171                 .family         = AF_INET6,
 172                 .checkentry     = checkentry,
 173                 .destroy        = destroy,
 174                 .target         = target,
 175                 .targetsize     = sizeof(struct xt_connmark_target_info),
 176                 .me             = THIS_MODULE
 177         },
 178 };
 179
 180 static int __init xt_connmark_init(void)
 181 {
 182         return xt_register_targets(xt_connmark_target,
 183                                    ARRAY_SIZE(xt_connmark_target));
 184 }
 185
 186 static void __exit xt_connmark_fini(void)
 187 {
 188         xt_unregister_targets(xt_connmark_target,
 189                               ARRAY_SIZE(xt_connmark_target));
 190 }
 191
 192 module_init(xt_connmark_init);
 193 module_exit(xt_connmark_fini);