| /* |
| * 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 (vlan_tx_tag_present(skb)) { |
| TCI = vlan_tx_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); |