/* * 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);