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DEFINITIONS
This source file includes following definitions.
- ebt_vlan_mt
- ebt_vlan_mt_check
- ebt_vlan_init
- ebt_vlan_fini
/*
* Description: EBTables 802.1Q match extension kernelspace module.
* Authors: Nick Fedchik <nick@fedchik.org.ua>
* 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 as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_vlan.h>
static int debug;
#define MODULE_VERS "0.6"
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "debug=1 is turn on debug messages");
MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
MODULE_LICENSE("GPL");
#define DEBUG_MSG(args...) if (debug) printk (KERN_DEBUG "ebt_vlan: " args)
#define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_
#define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return false; }
static bool
ebt_vlan_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
const struct ebt_vlan_info *info = par->matchinfo;
const struct vlan_hdr *fp;
struct vlan_hdr _frame;
unsigned short TCI; /* Whole TCI, given from parsed frame */
unsigned short id; /* VLAN ID, given from frame TCI */
unsigned char prio; /* user_priority, given from frame TCI */
/* VLAN encapsulated Type/Length field, given from orig frame */
__be16 encap;
fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame);
if (fp == NULL)
return false;
/* Tag Control Information (TCI) consists of the following elements:
* - User_priority. The user_priority field is three bits in length,
* interpreted as a binary number.
* - Canonical Format Indicator (CFI). The Canonical Format Indicator
* (CFI) is a single bit flag value. Currently ignored.
* - VLAN Identifier (VID). The VID is encoded as
* an unsigned binary number. */
TCI = ntohs(fp->h_vlan_TCI);
id = TCI & VLAN_VID_MASK;
prio = (TCI >> 13) & 0x7;
encap = fp->h_vlan_encapsulated_proto;
/* Checking VLAN Identifier (VID) */
if (GET_BITMASK(EBT_VLAN_ID))
EXIT_ON_MISMATCH(id, EBT_VLAN_ID);
/* Checking user_priority */
if (GET_BITMASK(EBT_VLAN_PRIO))
EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO);
/* Checking Encapsulated Proto (Length/Type) field */
if (GET_BITMASK(EBT_VLAN_ENCAP))
EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP);
return true;
}
static bool ebt_vlan_mt_check(const struct xt_mtchk_param *par)
{
struct ebt_vlan_info *info = par->matchinfo;
const struct ebt_entry *e = par->entryinfo;
/* Is it 802.1Q frame checked? */
if (e->ethproto != htons(ETH_P_8021Q)) {
DEBUG_MSG
("passed entry proto %2.4X is not 802.1Q (8100)\n",
(unsigned short) ntohs(e->ethproto));
return false;
}
/* Check for bitmask range
* True if even one bit is out of mask */
if (info->bitmask & ~EBT_VLAN_MASK) {
DEBUG_MSG("bitmask %2X is out of mask (%2X)\n",
info->bitmask, EBT_VLAN_MASK);
return false;
}
/* Check for inversion flags range */
if (info->invflags & ~EBT_VLAN_MASK) {
DEBUG_MSG("inversion flags %2X is out of mask (%2X)\n",
info->invflags, EBT_VLAN_MASK);
return false;
}
/* Reserved VLAN ID (VID) values
* -----------------------------
* 0 - The null VLAN ID.
* 1 - The default Port VID (PVID)
* 0x0FFF - Reserved for implementation use.
* if_vlan.h: VLAN_GROUP_ARRAY_LEN 4096. */
if (GET_BITMASK(EBT_VLAN_ID)) {
if (!!info->id) { /* if id!=0 => check vid range */
if (info->id > VLAN_GROUP_ARRAY_LEN) {
DEBUG_MSG
("id %d is out of range (1-4096)\n",
info->id);
return false;
}
/* Note: This is valid VLAN-tagged frame point.
* Any value of user_priority are acceptable,
* but should be ignored according to 802.1Q Std.
* So we just drop the prio flag. */
info->bitmask &= ~EBT_VLAN_PRIO;
}
/* Else, id=0 (null VLAN ID) => user_priority range (any?) */
}
if (GET_BITMASK(EBT_VLAN_PRIO)) {
if ((unsigned char) info->prio > 7) {
DEBUG_MSG("prio %d is out of range (0-7)\n",
info->prio);
return false;
}
}
/* Check for encapsulated proto range - it is possible to be
* any value for u_short range.
* if_ether.h: ETH_ZLEN 60 - Min. octets in frame sans FCS */
if (GET_BITMASK(EBT_VLAN_ENCAP)) {
if ((unsigned short) ntohs(info->encap) < ETH_ZLEN) {
DEBUG_MSG
("encap frame length %d is less than minimal\n",
ntohs(info->encap));
return false;
}
}
return true;
}
static struct xt_match ebt_vlan_mt_reg __read_mostly = {
.name = "vlan",
.revision = 0,
.family = NFPROTO_BRIDGE,
.match = ebt_vlan_mt,
.checkentry = ebt_vlan_mt_check,
.matchsize = XT_ALIGN(sizeof(struct ebt_vlan_info)),
.me = THIS_MODULE,
};
static int __init ebt_vlan_init(void)
{
DEBUG_MSG("ebtables 802.1Q extension module v"
MODULE_VERS "\n");
DEBUG_MSG("module debug=%d\n", !!debug);
return xt_register_match(&ebt_vlan_mt_reg);
}
static void __exit ebt_vlan_fini(void)
{
xt_unregister_match(&ebt_vlan_mt_reg);
}
module_init(ebt_vlan_init);
module_exit(ebt_vlan_fini);