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- /*
- * 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, see <http://www.gnu.org/licenses/>.
- */
- #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>
- #define MODULE_VERS "0.6"
- MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
- MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
- MODULE_LICENSE("GPL");
- #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, struct xt_action_param *par)
- {
- const struct ebt_vlan_info *info = par->matchinfo;
- 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;
- if (skb_vlan_tag_present(skb)) {
- TCI = skb_vlan_tag_get(skb);
- encap = skb->protocol;
- } else {
- const struct vlan_hdr *fp;
- struct vlan_hdr _frame;
- fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame);
- if (fp == NULL)
- return false;
- TCI = ntohs(fp->h_vlan_TCI);
- encap = fp->h_vlan_encapsulated_proto;
- }
- /* 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. */
- id = TCI & VLAN_VID_MASK;
- prio = (TCI >> 13) & 0x7;
- /* 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 int 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)) {
- pr_debug("passed entry proto %2.4X is not 802.1Q (8100)\n",
- ntohs(e->ethproto));
- return -EINVAL;
- }
- /* Check for bitmask range
- * True if even one bit is out of mask */
- if (info->bitmask & ~EBT_VLAN_MASK) {
- pr_debug("bitmask %2X is out of mask (%2X)\n",
- info->bitmask, EBT_VLAN_MASK);
- return -EINVAL;
- }
- /* Check for inversion flags range */
- if (info->invflags & ~EBT_VLAN_MASK) {
- pr_debug("inversion flags %2X is out of mask (%2X)\n",
- info->invflags, EBT_VLAN_MASK);
- return -EINVAL;
- }
- /* 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_N_VID 4096. */
- if (GET_BITMASK(EBT_VLAN_ID)) {
- if (!!info->id) { /* if id!=0 => check vid range */
- if (info->id > VLAN_N_VID) {
- pr_debug("id %d is out of range (1-4096)\n",
- info->id);
- return -EINVAL;
- }
- /* 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) {
- pr_debug("prio %d is out of range (0-7)\n",
- info->prio);
- return -EINVAL;
- }
- }
- /* 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) {
- pr_debug("encap frame length %d is less than "
- "minimal\n", ntohs(info->encap));
- return -EINVAL;
- }
- }
- return 0;
- }
- 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 = sizeof(struct ebt_vlan_info),
- .me = THIS_MODULE,
- };
- static int __init ebt_vlan_init(void)
- {
- pr_debug("ebtables 802.1Q extension module v" MODULE_VERS "\n");
- 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);
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