/* * Description: EBTables 802.1Q match extension kernelspace module. * Authors: Nick Fedchik * Bart De Schuymer * * 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 #include #include #include #include static unsigned char debug; #define MODULE_VERSION "0.6" MODULE_PARM(debug, "0-1b"); MODULE_PARM_DESC(debug, "debug=1 is turn on debug messages"); MODULE_AUTHOR("Nick Fedchik "); MODULE_DESCRIPTION("802.1Q match module (ebtables extension), v" MODULE_VERSION); MODULE_LICENSE("GPL"); #define DEBUG_MSG(...) if (debug) printk (KERN_DEBUG "ebt_vlan: " __VA_ARGS__) #define INV_FLAG(_inv_flag_) (info->invflags & _inv_flag_) ? "!" : "" #define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_ #define SET_BITMASK(_BIT_MASK_) info->bitmask |= _BIT_MASK_ #define EXIT_ON_MISMATCH(_MATCH_,_MASK_) if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return 1; /* * Function description: ebt_filter_vlan() is main engine for * checking passed 802.1Q frame according to * the passed extension parameters (in the *data buffer) * ebt_filter_vlan() is called after successfull check the rule params * by ebt_check_vlan() function. * Parameters: * const struct sk_buff *skb - pointer to passed ethernet frame buffer * const void *data - pointer to passed extension parameters * unsigned int datalen - length of passed *data buffer * const struct net_device *in - * const struct net_device *out - * const struct ebt_counter *c - * Returned values: * 0 - ok (all rule params matched) * 1 - miss (rule params not acceptable to the parsed frame) */ static int ebt_filter_vlan(const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const void *data, unsigned int datalen) { struct ebt_vlan_info *info = (struct ebt_vlan_info *) data; /* userspace data */ struct vlan_ethhdr *frame = (struct vlan_ethhdr *) skb->mac.raw; /* Passed tagged 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 */ unsigned short encap; /* VLAN encapsulated Type/Length field, given from orig frame */ /* * 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(frame->h_vlan_TCI); id = TCI & VLAN_VID_MASK; prio = (TCI >> 13) & 0x7; encap = frame->h_vlan_encapsulated_proto; /* * Checking VLAN Identifier (VID) */ if (GET_BITMASK(EBT_VLAN_ID)) { /* Is VLAN ID parsed? */ EXIT_ON_MISMATCH(id, EBT_VLAN_ID); } /* * Checking user_priority */ if (GET_BITMASK(EBT_VLAN_PRIO)) { /* Is VLAN user_priority parsed? */ EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO); } /* * Checking Encapsulated Proto (Length/Type) field */ if (GET_BITMASK(EBT_VLAN_ENCAP)) { /* Is VLAN Encap parsed? */ EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP); } /* * All possible extension parameters was parsed. * If rule never returned by missmatch, then all ok. */ return 0; } /* * Function description: ebt_vlan_check() is called when userspace * delivers the table entry to the kernel, * and to check that userspace doesn't give a bad table. * Parameters: * const char *tablename - table name string * unsigned int hooknr - hook number * const struct ebt_entry *e - ebtables entry basic set * const void *data - pointer to passed extension parameters * unsigned int datalen - length of passed *data buffer * Returned values: * 0 - ok (all delivered rule params are correct) * 1 - miss (rule params is out of range, invalid, incompatible, etc.) */ static int ebt_check_vlan(const char *tablename, unsigned int hooknr, const struct ebt_entry *e, void *data, unsigned int datalen) { struct ebt_vlan_info *info = (struct ebt_vlan_info *) data; /* * Parameters buffer overflow check */ if (datalen != sizeof(struct ebt_vlan_info)) { DEBUG_MSG ("passed size %d is not eq to ebt_vlan_info (%d)\n", datalen, sizeof(struct ebt_vlan_info)); return -EINVAL; } /* * Is it 802.1Q frame checked? */ if (e->ethproto != __constant_htons(ETH_P_8021Q)) { DEBUG_MSG ("passed entry proto %2.4X is not 802.1Q (8100)\n", (unsigned short) ntohs(e->ethproto)); return -EINVAL; } /* * 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 -EINVAL; } /* * 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 -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_GROUP_ARRAY_LEN 4096. */ if (GET_BITMASK(EBT_VLAN_ID)) { /* when vlan-id param was spec-ed */ 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 -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) { DEBUG_MSG ("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) { DEBUG_MSG ("encap frame length %d is less than minimal\n", ntohs(info->encap)); return -EINVAL; } } return 0; } static struct ebt_match filter_vlan = { .name = EBT_VLAN_MATCH, .match = ebt_filter_vlan, .check = ebt_check_vlan, .me = THIS_MODULE, }; /* * Module initialization function. */ static int __init init(void) { DEBUG_MSG("ebtables 802.1Q extension module v" MODULE_VERSION "\n"); DEBUG_MSG("module debug=%d\n", !!debug); return ebt_register_match(&filter_vlan); } /* * Module "finalization" function */ static void __exit fini(void) { ebt_unregister_match(&filter_vlan); } module_init(init); module_exit(fini);