net/ipv4/netfilter/ipt_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_ipv4/ipt_physdev.h>
  14 #include <linux/netfilter_ipv4/ip_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
  23 static int
  24 match(const struct sk_buff *skb,
  25       const struct net_device *in,
  26       const struct net_device *out,
  27       const void *matchinfo,
  28       int offset,
  29       int *hotdrop)
  30 {
  31         int i;
  32         static const char nulldevname[IFNAMSIZ];
  33         const struct ipt_physdev_info *info = matchinfo;
  34         unsigned int ret;
  35         const char *indev, *outdev;
  36         struct nf_bridge_info *nf_bridge;
  37
  38         /* Not a bridged IP packet or no info available yet:
  39          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  40          * the destination device will be a bridge. */
  41         if (!(nf_bridge = skb->nf_bridge)) {
  42                 /* Return MATCH if the invert flags of the used options are on */
  43                 if ((info->bitmask & IPT_PHYSDEV_OP_BRIDGED) &&
  44                     !(info->invert & IPT_PHYSDEV_OP_BRIDGED))
  45                         return NOMATCH;
  46                 if ((info->bitmask & IPT_PHYSDEV_OP_ISIN) &&
  47                     !(info->invert & IPT_PHYSDEV_OP_ISIN))
  48                         return NOMATCH;
  49                 if ((info->bitmask & IPT_PHYSDEV_OP_ISOUT) &&
  50                     !(info->invert & IPT_PHYSDEV_OP_ISOUT))
  51                         return NOMATCH;
  52                 if ((info->bitmask & IPT_PHYSDEV_OP_IN) &&
  53                     !(info->invert & IPT_PHYSDEV_OP_IN))
  54                         return NOMATCH;
  55                 if ((info->bitmask & IPT_PHYSDEV_OP_OUT) &&
  56                     !(info->invert & IPT_PHYSDEV_OP_OUT))
  57                         return NOMATCH;
  58                 return MATCH;
  59         }
  60
  61         /* This only makes sense in the FORWARD and POSTROUTING chains */
  62         if ((info->bitmask & IPT_PHYSDEV_OP_BRIDGED) &&
  63             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  64             !(info->invert & IPT_PHYSDEV_OP_BRIDGED)))
  65                 return NOMATCH;
  66
  67         if ((info->bitmask & IPT_PHYSDEV_OP_ISIN &&
  68             (!nf_bridge->physindev ^ !!(info->invert & IPT_PHYSDEV_OP_ISIN))) ||
  69             (info->bitmask & IPT_PHYSDEV_OP_ISOUT &&
  70             (!nf_bridge->physoutdev ^ !!(info->invert & IPT_PHYSDEV_OP_ISOUT))))
  71                 return NOMATCH;
  72
  73         if (!(info->bitmask & IPT_PHYSDEV_OP_IN))
  74                 goto match_outdev;
  75         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  76         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  77                 ret |= (((const unsigned int *)indev)[i]
  78                         ^ ((const unsigned int *)info->physindev)[i])
  79                         & ((const unsigned int *)info->in_mask)[i];
  80         }
  81
  82         if ((ret == 0) ^ !(info->invert & IPT_PHYSDEV_OP_IN))
  83                 return NOMATCH;
  84
  85 match_outdev:
  86         if (!(info->bitmask & IPT_PHYSDEV_OP_OUT))
  87                 return MATCH;
  88         outdev = nf_bridge->physoutdev ?
  89                  nf_bridge->physoutdev->name : nulldevname;
  90         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  91                 ret |= (((const unsigned int *)outdev)[i]
  92                         ^ ((const unsigned int *)info->physoutdev)[i])
  93                         & ((const unsigned int *)info->out_mask)[i];
  94         }
  95
  96         return (ret != 0) ^ !(info->invert & IPT_PHYSDEV_OP_OUT);
  97 }
  98
  99 static int
 100 checkentry(const char *tablename,
 101                        const struct ipt_ip *ip,
 102                        void *matchinfo,
 103                        unsigned int matchsize,
 104                        unsigned int hook_mask)
 105 {
 106         const struct ipt_physdev_info *info = matchinfo;
 107
 108         if (matchsize != IPT_ALIGN(sizeof(struct ipt_physdev_info)))
 109                 return 0;
 110         if (!(info->bitmask & IPT_PHYSDEV_OP_MASK) ||
 111             info->bitmask & ~IPT_PHYSDEV_OP_MASK)
 112                 return 0;
 113         return 1;
 114 }
 115
 116 static struct ipt_match physdev_match = {
 117         .name           = "physdev",
 118         .match          = &match,
 119         .checkentry     = &checkentry,
 120         .me             = THIS_MODULE,
 121 };
 122
 123 static int __init init(void)
 124 {
 125         return ipt_register_match(&physdev_match);
 126 }
 127
 128 static void __exit fini(void)
 129 {
 130         ipt_unregister_match(&physdev_match);
 131 }
 132
 133 module_init(init);
 134 module_exit(fini);