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 #define MATCH   1
  18 #define NOMATCH 0
  19
  20 MODULE_LICENSE("GPL");
  21 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  22 MODULE_DESCRIPTION("iptables bridge physical device match module");
  23 MODULE_ALIAS("ipt_physdev");
  24 MODULE_ALIAS("ip6t_physdev");
  25
  26 static int
  27 match(const struct sk_buff *skb,
  28       const struct net_device *in,
  29       const struct net_device *out,
  30       const struct xt_match *match,
  31       const void *matchinfo,
  32       int offset,
  33       unsigned int protoff,
  34       int *hotdrop)
  35 {
  36         int i;
  37         static const char nulldevname[IFNAMSIZ];
  38         const struct xt_physdev_info *info = matchinfo;
  39         unsigned int ret;
  40         const char *indev, *outdev;
  41         struct nf_bridge_info *nf_bridge;
  42
  43         /* Not a bridged IP packet or no info available yet:
  44          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  45          * the destination device will be a bridge. */
  46         if (!(nf_bridge = skb->nf_bridge)) {
  47                 /* Return MATCH if the invert flags of the used options are on */
  48                 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  49                     !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  50                         return NOMATCH;
  51                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  52                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  53                         return NOMATCH;
  54                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  55                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  56                         return NOMATCH;
  57                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  58                     !(info->invert & XT_PHYSDEV_OP_IN))
  59                         return NOMATCH;
  60                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  61                     !(info->invert & XT_PHYSDEV_OP_OUT))
  62                         return NOMATCH;
  63                 return MATCH;
  64         }
  65
  66         /* This only makes sense in the FORWARD and POSTROUTING chains */
  67         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  68             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  69             !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  70                 return NOMATCH;
  71
  72         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  73             (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  74             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  75             (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  76                 return NOMATCH;
  77
  78         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  79                 goto match_outdev;
  80         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  81         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  82                 ret |= (((const unsigned int *)indev)[i]
  83                         ^ ((const unsigned int *)info->physindev)[i])
  84                         & ((const unsigned int *)info->in_mask)[i];
  85         }
  86
  87         if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN))
  88                 return NOMATCH;
  89
  90 match_outdev:
  91         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  92                 return MATCH;
  93         outdev = nf_bridge->physoutdev ?
  94                  nf_bridge->physoutdev->name : nulldevname;
  95         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  96                 ret |= (((const unsigned int *)outdev)[i]
  97                         ^ ((const unsigned int *)info->physoutdev)[i])
  98                         & ((const unsigned int *)info->out_mask)[i];
  99         }
 100
 101         return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT);
 102 }
 103
 104 static int
 105 checkentry(const char *tablename,
 106                        const void *ip,
 107                        const struct xt_match *match,
 108                        void *matchinfo,
 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         if (info->bitmask & XT_PHYSDEV_OP_OUT &&
 117             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 118              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 119             hook_mask & ((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_FORWARD) |
 120                          (1 << NF_IP_POST_ROUTING))) {
 121                 printk(KERN_WARNING "physdev match: using --physdev-out in the "
 122                        "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
 123                        "traffic is not supported anymore.\n");
 124                 if (hook_mask & (1 << NF_IP_LOCAL_OUT))
 125                         return 0;
 126         }
 127         return 1;
 128 }
 129
 130 static struct xt_match xt_physdev_match[] = {
 131         {
 132                 .name           = "physdev",
 133                 .family         = AF_INET,
 134                 .checkentry     = checkentry,
 135                 .match          = match,
 136                 .matchsize      = sizeof(struct xt_physdev_info),
 137                 .me             = THIS_MODULE,
 138         },
 139         {
 140                 .name           = "physdev",
 141                 .family         = AF_INET6,
 142                 .checkentry     = checkentry,
 143                 .match          = match,
 144                 .matchsize      = sizeof(struct xt_physdev_info),
 145                 .me             = THIS_MODULE,
 146         },
 147 };
 148
 149 static int __init xt_physdev_init(void)
 150 {
 151         return xt_register_matches(xt_physdev_match,
 152                                    ARRAY_SIZE(xt_physdev_match));
 153 }
 154
 155 static void __exit xt_physdev_fini(void)
 156 {
 157         xt_unregister_matches(xt_physdev_match, ARRAY_SIZE(xt_physdev_match));
 158 }
 159
 160 module_init(xt_physdev_init);
 161 module_exit(xt_physdev_fini);