net/netfilter/xt_physdev.c

   1 /* Kernel module to match the bridge port in and
   2  * out device for IP packets coming into contact with a bridge. */
   3
   4 /* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/netfilter/xt_physdev.h>
  14 #include <linux/netfilter/x_tables.h>
  15 #include <linux/netfilter_bridge.h>
  16 #define MATCH   1
  17 #define NOMATCH 0
  18
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  21 MODULE_DESCRIPTION("iptables bridge physical device match module");
  22 MODULE_ALIAS("ipt_physdev");
  23 MODULE_ALIAS("ip6t_physdev");
  24
  25 static int
  26 match(const struct sk_buff *skb,
  27       const struct net_device *in,
  28       const struct net_device *out,
  29       const void *matchinfo,
  30       int offset,
  31       unsigned int protoff,
  32       int *hotdrop)
  33 {
  34         int i;
  35         static const char nulldevname[IFNAMSIZ];
  36         const struct xt_physdev_info *info = matchinfo;
  37         unsigned int ret;
  38         const char *indev, *outdev;
  39         struct nf_bridge_info *nf_bridge;
  40
  41         /* Not a bridged IP packet or no info available yet:
  42          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  43          * the destination device will be a bridge. */
  44         if (!(nf_bridge = skb->nf_bridge)) {
  45                 /* Return MATCH if the invert flags of the used options are on */
  46                 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  47                     !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  48                         return NOMATCH;
  49                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  50                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  51                         return NOMATCH;
  52                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  53                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  54                         return NOMATCH;
  55                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  56                     !(info->invert & XT_PHYSDEV_OP_IN))
  57                         return NOMATCH;
  58                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  59                     !(info->invert & XT_PHYSDEV_OP_OUT))
  60                         return NOMATCH;
  61                 return MATCH;
  62         }
  63
  64         /* This only makes sense in the FORWARD and POSTROUTING chains */
  65         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  66             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  67             !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  68                 return NOMATCH;
  69
  70         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  71             (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  72             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  73             (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  74                 return NOMATCH;
  75
  76         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  77                 goto match_outdev;
  78         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  79         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  80                 ret |= (((const unsigned int *)indev)[i]
  81                         ^ ((const unsigned int *)info->physindev)[i])
  82                         & ((const unsigned int *)info->in_mask)[i];
  83         }
  84
  85         if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN))
  86                 return NOMATCH;
  87
  88 match_outdev:
  89         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  90                 return MATCH;
  91         outdev = nf_bridge->physoutdev ?
  92                  nf_bridge->physoutdev->name : nulldevname;
  93         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  94                 ret |= (((const unsigned int *)outdev)[i]
  95                         ^ ((const unsigned int *)info->physoutdev)[i])
  96                         & ((const unsigned int *)info->out_mask)[i];
  97         }
  98
  99         return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT);
 100 }
 101
 102 static int
 103 checkentry(const char *tablename,
 104                        const void *ip,
 105                        void *matchinfo,
 106                        unsigned int matchsize,
 107                        unsigned int hook_mask)
 108 {
 109         const struct xt_physdev_info *info = matchinfo;
 110
 111         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 112             info->bitmask & ~XT_PHYSDEV_OP_MASK)
 113                 return 0;
 114         return 1;
 115 }
 116
 117 static struct xt_match physdev_match = {
 118         .name           = "physdev",
 119         .match          = match,
 120         .matchsize      = sizeof(struct xt_physdev_info),
 121         .checkentry     = checkentry,
 122         .me             = THIS_MODULE,
 123 };
 124
 125 static struct xt_match physdev6_match = {
 126         .name           = "physdev",
 127         .match          = match,
 128         .matchsize      = sizeof(struct xt_physdev_info),
 129         .checkentry     = checkentry,
 130         .me             = THIS_MODULE,
 131 };
 132
 133 static int __init init(void)
 134 {
 135         int ret;
 136
 137         ret = xt_register_match(AF_INET, &physdev_match);
 138         if (ret < 0)
 139                 return ret;
 140
 141         ret = xt_register_match(AF_INET6, &physdev6_match);
 142         if (ret < 0)
 143                 xt_unregister_match(AF_INET, &physdev_match);
 144
 145         return ret;
 146 }
 147
 148 static void __exit fini(void)
 149 {
 150         xt_unregister_match(AF_INET, &physdev_match);
 151         xt_unregister_match(AF_INET6, &physdev6_match);
 152 }
 153
 154 module_init(init);
 155 module_exit(fini);