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 struct xt_match *match,
  30       const void *matchinfo,
  31       int offset,
  32       unsigned int protoff,
  33       int *hotdrop)
  34 {
  35         int i;
  36         static const char nulldevname[IFNAMSIZ];
  37         const struct xt_physdev_info *info = matchinfo;
  38         unsigned int ret;
  39         const char *indev, *outdev;
  40         struct nf_bridge_info *nf_bridge;
  41
  42         /* Not a bridged IP packet or no info available yet:
  43          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  44          * the destination device will be a bridge. */
  45         if (!(nf_bridge = skb->nf_bridge)) {
  46                 /* Return MATCH if the invert flags of the used options are on */
  47                 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  48                     !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  49                         return NOMATCH;
  50                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  51                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  52                         return NOMATCH;
  53                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  54                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  55                         return NOMATCH;
  56                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  57                     !(info->invert & XT_PHYSDEV_OP_IN))
  58                         return NOMATCH;
  59                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  60                     !(info->invert & XT_PHYSDEV_OP_OUT))
  61                         return NOMATCH;
  62                 return MATCH;
  63         }
  64
  65         /* This only makes sense in the FORWARD and POSTROUTING chains */
  66         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  67             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  68             !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  69                 return NOMATCH;
  70
  71         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  72             (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  73             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  74             (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  75                 return NOMATCH;
  76
  77         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  78                 goto match_outdev;
  79         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  80         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  81                 ret |= (((const unsigned int *)indev)[i]
  82                         ^ ((const unsigned int *)info->physindev)[i])
  83                         & ((const unsigned int *)info->in_mask)[i];
  84         }
  85
  86         if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN))
  87                 return NOMATCH;
  88
  89 match_outdev:
  90         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  91                 return MATCH;
  92         outdev = nf_bridge->physoutdev ?
  93                  nf_bridge->physoutdev->name : nulldevname;
  94         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  95                 ret |= (((const unsigned int *)outdev)[i]
  96                         ^ ((const unsigned int *)info->physoutdev)[i])
  97                         & ((const unsigned int *)info->out_mask)[i];
  98         }
  99
 100         return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT);
 101 }
 102
 103 static int
 104 checkentry(const char *tablename,
 105                        const void *ip,
 106                        const struct xt_match *match,
 107                        void *matchinfo,
 108                        unsigned int matchsize,
 109                        unsigned int hook_mask)
 110 {
 111         const struct xt_physdev_info *info = matchinfo;
 112
 113         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 114             info->bitmask & ~XT_PHYSDEV_OP_MASK)
 115                 return 0;
 116         return 1;
 117 }
 118
 119 static struct xt_match physdev_match = {
 120         .name           = "physdev",
 121         .match          = match,
 122         .matchsize      = sizeof(struct xt_physdev_info),
 123         .checkentry     = checkentry,
 124         .family         = AF_INET,
 125         .me             = THIS_MODULE,
 126 };
 127
 128 static struct xt_match physdev6_match = {
 129         .name           = "physdev",
 130         .match          = match,
 131         .matchsize      = sizeof(struct xt_physdev_info),
 132         .checkentry     = checkentry,
 133         .family         = AF_INET6,
 134         .me             = THIS_MODULE,
 135 };
 136
 137 static int __init xt_physdev_init(void)
 138 {
 139         int ret;
 140
 141         ret = xt_register_match(&physdev_match);
 142         if (ret < 0)
 143                 return ret;
 144
 145         ret = xt_register_match(&physdev6_match);
 146         if (ret < 0)
 147                 xt_unregister_match(&physdev_match);
 148
 149         return ret;
 150 }
 151
 152 static void __exit xt_physdev_fini(void)
 153 {
 154         xt_unregister_match(&physdev_match);
 155         xt_unregister_match(&physdev6_match);
 156 }
 157
 158 module_init(xt_physdev_init);
 159 module_exit(xt_physdev_fini);