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                         (*pskb)->mark = mark ^ diff;
  82                         break;
  83                 }
  84         }
  85
  86         return XT_CONTINUE;
  87 }
  88
  89 static int
  90 checkentry(const char *tablename,
  91            const void *entry,
  92            const struct xt_target *target,
  93            void *targinfo,
  94            unsigned int hook_mask)
  95 {
  96         struct xt_connmark_target_info *matchinfo = targinfo;
  97
  98         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
  99                 printk(KERN_WARNING "can't load conntrack support for "
 100                                     "proto=%d\n", target->family);
 101                 return 0;
 102         }
 103         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
 104                 if (strcmp(tablename, "mangle") != 0) {
 105                         printk(KERN_WARNING "CONNMARK: restore can only be "
 106                                "called from \"mangle\" table, not \"%s\"\n",
 107                                tablename);
 108                         return 0;
 109                 }
 110         }
 111         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 112                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 113                 return 0;
 114         }
 115         return 1;
 116 }
 117
 118 static void
 119 destroy(const struct xt_target *target, void *targinfo)
 120 {
 121         nf_ct_l3proto_module_put(target->family);
 122 }
 123
 124 #ifdef CONFIG_COMPAT
 125 struct compat_xt_connmark_target_info {
 126         compat_ulong_t  mark, mask;
 127         u_int8_t        mode;
 128         u_int8_t        __pad1;
 129         u_int16_t       __pad2;
 130 };
 131
 132 static void compat_from_user(void *dst, void *src)
 133 {
 134         struct compat_xt_connmark_target_info *cm = src;
 135         struct xt_connmark_target_info m = {
 136                 .mark   = cm->mark,
 137                 .mask   = cm->mask,
 138                 .mode   = cm->mode,
 139         };
 140         memcpy(dst, &m, sizeof(m));
 141 }
 142
 143 static int compat_to_user(void __user *dst, void *src)
 144 {
 145         struct xt_connmark_target_info *m = src;
 146         struct compat_xt_connmark_target_info cm = {
 147                 .mark   = m->mark,
 148                 .mask   = m->mask,
 149                 .mode   = m->mode,
 150         };
 151         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 152 }
 153 #endif /* CONFIG_COMPAT */
 154
 155 static struct xt_target xt_connmark_target[] = {
 156         {
 157                 .name           = "CONNMARK",
 158                 .family         = AF_INET,
 159                 .checkentry     = checkentry,
 160                 .destroy        = destroy,
 161                 .target         = target,
 162                 .targetsize     = sizeof(struct xt_connmark_target_info),
 163 #ifdef CONFIG_COMPAT
 164                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 165                 .compat_from_user = compat_from_user,
 166                 .compat_to_user = compat_to_user,
 167 #endif
 168                 .me             = THIS_MODULE
 169         },
 170         {
 171                 .name           = "CONNMARK",
 172                 .family         = AF_INET6,
 173                 .checkentry     = checkentry,
 174                 .destroy        = destroy,
 175                 .target         = target,
 176                 .targetsize     = sizeof(struct xt_connmark_target_info),
 177                 .me             = THIS_MODULE
 178         },
 179 };
 180
 181 static int __init xt_connmark_init(void)
 182 {
 183         return xt_register_targets(xt_connmark_target,
 184                                    ARRAY_SIZE(xt_connmark_target));
 185 }
 186
 187 static void __exit xt_connmark_fini(void)
 188 {
 189         xt_unregister_targets(xt_connmark_target,
 190                               ARRAY_SIZE(xt_connmark_target));
 191 }
 192
 193 module_init(xt_connmark_init);
 194 module_exit(xt_connmark_fini);