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_bridge.h>
  14 #include <linux/netfilter/xt_physdev.h>
  15 #include <linux/netfilter/x_tables.h>
  16 #include <linux/netfilter_bridge.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  20 MODULE_DESCRIPTION("iptables bridge physical device match module");
  21 MODULE_ALIAS("ipt_physdev");
  22 MODULE_ALIAS("ip6t_physdev");
  23
  24 static bool
  25 match(const struct sk_buff *skb,
  26       const struct net_device *in,
  27       const struct net_device *out,
  28       const struct xt_match *match,
  29       const void *matchinfo,
  30       int offset,
  31       unsigned int protoff,
  32       bool *hotdrop)
  33 {
  34         int i;
  35         static const char nulldevname[IFNAMSIZ];
  36         const struct xt_physdev_info *info = matchinfo;
  37         bool 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 false;
  49                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  50                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  51                         return false;
  52                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  53                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  54                         return false;
  55                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  56                     !(info->invert & XT_PHYSDEV_OP_IN))
  57                         return false;
  58                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  59                     !(info->invert & XT_PHYSDEV_OP_OUT))
  60                         return false;
  61                 return true;
  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 false;
  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 false;
  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 = false; 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 ^ !(info->invert & XT_PHYSDEV_OP_IN))
  86                 return false;
  87
  88 match_outdev:
  89         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  90                 return true;
  91         outdev = nf_bridge->physoutdev ?
  92                  nf_bridge->physoutdev->name : nulldevname;
  93         for (i = 0, ret = false; 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 ^ !(info->invert & XT_PHYSDEV_OP_OUT);
 100 }
 101
 102 static int
 103 checkentry(const char *tablename,
 104                        const void *ip,
 105                        const struct xt_match *match,
 106                        void *matchinfo,
 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         if (info->bitmask & XT_PHYSDEV_OP_OUT &&
 115             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 116              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 117             hook_mask & ((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_FORWARD) |
 118                          (1 << NF_IP_POST_ROUTING))) {
 119                 printk(KERN_WARNING "physdev match: using --physdev-out in the "
 120                        "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
 121                        "traffic is not supported anymore.\n");
 122                 if (hook_mask & (1 << NF_IP_LOCAL_OUT))
 123                         return 0;
 124         }
 125         return 1;
 126 }
 127
 128 static struct xt_match xt_physdev_match[] = {
 129         {
 130                 .name           = "physdev",
 131                 .family         = AF_INET,
 132                 .checkentry     = checkentry,
 133                 .match          = match,
 134                 .matchsize      = sizeof(struct xt_physdev_info),
 135                 .me             = THIS_MODULE,
 136         },
 137         {
 138                 .name           = "physdev",
 139                 .family         = AF_INET6,
 140                 .checkentry     = checkentry,
 141                 .match          = match,
 142                 .matchsize      = sizeof(struct xt_physdev_info),
 143                 .me             = THIS_MODULE,
 144         },
 145 };
 146
 147 static int __init xt_physdev_init(void)
 148 {
 149         return xt_register_matches(xt_physdev_match,
 150                                    ARRAY_SIZE(xt_physdev_match));
 151 }
 152
 153 static void __exit xt_physdev_fini(void)
 154 {
 155         xt_unregister_matches(xt_physdev_match, ARRAY_SIZE(xt_physdev_match));
 156 }
 157
 158 module_init(xt_physdev_init);
 159 module_exit(xt_physdev_fini);