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/* Kernel module to match the bridge port in and
* out device for IP packets coming into contact with a bridge. */
/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter/xt_physdev.h>
#include <linux/netfilter/x_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
MODULE_DESCRIPTION("Xtables: Bridge physical device match");
MODULE_ALIAS("ipt_physdev");
MODULE_ALIAS("ip6t_physdev");
static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
{
const unsigned long *a = (const unsigned long *)_a;
const unsigned long *b = (const unsigned long *)_b;
const unsigned long *mask = (const unsigned long *)_mask;
unsigned long ret;
ret = (a[0] ^ b[0]) & mask[0];
if (IFNAMSIZ > sizeof(unsigned long))
ret |= (a[1] ^ b[1]) & mask[1];
if (IFNAMSIZ > 2 * sizeof(unsigned long))
ret |= (a[2] ^ b[2]) & mask[2];
if (IFNAMSIZ > 3 * sizeof(unsigned long))
ret |= (a[3] ^ b[3]) & mask[3];
BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
return ret;
}
static bool
physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
const struct xt_physdev_info *info = par->matchinfo;
unsigned long ret;
const char *indev, *outdev;
const 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 & XT_PHYSDEV_OP_BRIDGED) &&
!(info->invert & XT_PHYSDEV_OP_BRIDGED))
return false;
if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
!(info->invert & XT_PHYSDEV_OP_ISIN))
return false;
if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
!(info->invert & XT_PHYSDEV_OP_ISOUT))
return false;
if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
!(info->invert & XT_PHYSDEV_OP_IN))
return false;
if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
!(info->invert & XT_PHYSDEV_OP_OUT))
return false;
return true;
}
/* This only makes sense in the FORWARD and POSTROUTING chains */
if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
(!!(nf_bridge->mask & BRNF_BRIDGED) ^
!(info->invert & XT_PHYSDEV_OP_BRIDGED)))
return false;
if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
(!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
(info->bitmask & XT_PHYSDEV_OP_ISOUT &&
(!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
return false;
if (!(info->bitmask & XT_PHYSDEV_OP_IN))
goto match_outdev;
indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
ret = ifname_compare(indev, info->physindev, info->in_mask);
if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
return false;
match_outdev:
if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
return true;
outdev = nf_bridge->physoutdev ?
nf_bridge->physoutdev->name : nulldevname;
ret = ifname_compare(outdev, info->physoutdev, info->out_mask);
return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
}
static bool physdev_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_physdev_info *info = par->matchinfo;
if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
info->bitmask & ~XT_PHYSDEV_OP_MASK)
return false;
if (info->bitmask & XT_PHYSDEV_OP_OUT &&
(!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
info->invert & XT_PHYSDEV_OP_BRIDGED) &&
par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
printk(KERN_WARNING "physdev match: using --physdev-out in the "
"OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
"traffic is not supported anymore.\n");
if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
return false;
}
return true;
}
static struct xt_match physdev_mt_reg __read_mostly = {
.name = "physdev",
.revision = 0,
.family = NFPROTO_UNSPEC,
.checkentry = physdev_mt_check,
.match = physdev_mt,
.matchsize = sizeof(struct xt_physdev_info),
.me = THIS_MODULE,
};
static int __init physdev_mt_init(void)
{
return xt_register_match(&physdev_mt_reg);
}
static void __exit physdev_mt_exit(void)
{
xt_unregister_match(&physdev_mt_reg);
}
module_init(physdev_mt_init);
module_exit(physdev_mt_exit);
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