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/* Kernel module to match the bridge port in and
* out device for IP packets coming into contact with a bridge. */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ipt_physdev.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_bridge.h>
#include <linux/netdevice.h>
#define MATCH 1
#define NOMATCH 0
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
const void *hdr,
u_int16_t datalen,
int *hotdrop)
{
int i;
static const char nulldevname[IFNAMSIZ] = { 0 };
const struct ipt_physdev_info *info = matchinfo;
unsigned long ret;
const char *indev, *outdev;
struct nf_bridge_info *nf_bridge;
/* Not a bridged IP packet or no info available yet:
* LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
* the destination device will be a bridge. */
if (!(nf_bridge = skb->nf_bridge)) {
/* Return MATCH if the invert flags of the used options are on */
if ((info->bitmask & IPT_PHYSDEV_OP_BRIDGED) &&
!(info->invert & IPT_PHYSDEV_OP_BRIDGED))
return NOMATCH;
if ((info->bitmask & IPT_PHYSDEV_OP_ISIN) &&
!(info->invert & IPT_PHYSDEV_OP_ISIN))
return NOMATCH;
if ((info->bitmask & IPT_PHYSDEV_OP_ISOUT) &&
!(info->invert & IPT_PHYSDEV_OP_ISOUT))
return NOMATCH;
if ((info->bitmask & IPT_PHYSDEV_OP_IN) &&
!(info->invert & IPT_PHYSDEV_OP_IN))
return NOMATCH;
if ((info->bitmask & IPT_PHYSDEV_OP_OUT) &&
!(info->invert & IPT_PHYSDEV_OP_OUT))
return NOMATCH;
return MATCH;
}
/* This only makes sense in the FORWARD and POSTROUTING chains */
if ((info->bitmask & IPT_PHYSDEV_OP_BRIDGED) &&
(!!(nf_bridge->mask & BRNF_BRIDGED) ^
!(info->invert & IPT_PHYSDEV_OP_BRIDGED)))
return NOMATCH;
if ((info->bitmask & IPT_PHYSDEV_OP_ISIN &&
(!nf_bridge->physindev ^ !!(info->invert & IPT_PHYSDEV_OP_ISIN))) ||
(info->bitmask & IPT_PHYSDEV_OP_ISOUT &&
(!nf_bridge->physoutdev ^ !!(info->invert & IPT_PHYSDEV_OP_ISOUT))))
return NOMATCH;
if (!(info->bitmask & IPT_PHYSDEV_OP_IN))
goto match_outdev;
indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
ret |= (((const unsigned long *)indev)[i]
^ ((const unsigned long *)info->physindev)[i])
& ((const unsigned long *)info->in_mask)[i];
}
if ((ret == 0) ^ !(info->invert & IPT_PHYSDEV_OP_IN))
return NOMATCH;
match_outdev:
if (!(info->bitmask & IPT_PHYSDEV_OP_OUT))
return MATCH;
outdev = nf_bridge->physoutdev ?
nf_bridge->physoutdev->name : nulldevname;
for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
ret |= (((const unsigned long *)outdev)[i]
^ ((const unsigned long *)info->physoutdev)[i])
& ((const unsigned long *)info->out_mask)[i];
}
return (ret != 0) ^ !(info->invert & IPT_PHYSDEV_OP_OUT);
}
static int
checkentry(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
const struct ipt_physdev_info *info = matchinfo;
if (matchsize != IPT_ALIGN(sizeof(struct ipt_physdev_info)))
return 0;
if (!(info->bitmask & IPT_PHYSDEV_OP_MASK) ||
info->bitmask & ~IPT_PHYSDEV_OP_MASK)
return 0;
return 1;
}
static struct ipt_match physdev_match = {
.name = "physdev",
.match = &match,
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ipt_register_match(&physdev_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&physdev_match);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
EXPORT_NO_SYMBOLS;
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