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