/* * 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 "0.4 (" __DATE__ " " __TIME__ ")" 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 __FILE__ ":" __FUNCTION__ ": " __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. This field allows the tagged frame to carry user_priority * information across Bridged LANs in which individual LAN segments may be unable to signal * priority information (e.g., 802.3/Ethernet segments). * The user_priority field is three bits in length, * interpreted as a binary number. The user_priority is therefore * capable of representing eight priority levels, 0 through 7. * The use and interpretation of this field is defined in ISO/IEC 15802-3. * - Canonical Format Indicator (CFI). This field is used, * in 802.3/Ethernet, to signal the presence or absence * of a RIF field, and, in combination with the Non-canonical Format Indicator (NCFI) carried * in the RIF, to signal the bit order of address information carried in the encapsulated * frame. The Canonical Format Indicator (CFI) is a single bit flag value. * - VLAN Identifier (VID). This field uniquely identifies the VLAN to * which the frame belongs. The twelve-bit VLAN Identifier (VID) field * uniquely identify the VLAN to which the frame belongs. * The VID is encoded as an unsigned binary number. */ TCI = ntohs (frame->h_vlan_TCI); id = TCI & 0xFFF; prio = TCI >> 13; encap = frame->h_vlan_encapsulated_proto; /* * First step is to check is null VLAN ID present * in the parsed frame */ if (!(id)) { /* * Checking VLAN Identifier (VID) */ if (GET_BITMASK (EBT_VLAN_ID)) { /* Is VLAN ID parsed? */ EXIT_ON_MISMATCH (id, EBT_VLAN_ID); DEBUG_MSG ("matched rule id=%s%d for frame id=%d\n", INV_FLAG (EBT_VLAN_ID), info->id, id); } } else { /* * Checking user_priority */ if (GET_BITMASK (EBT_VLAN_PRIO)) { /* Is VLAN user_priority parsed? */ EXIT_ON_MISMATCH (prio, EBT_VLAN_PRIO); DEBUG_MSG ("matched rule prio=%s%d for frame prio=%d\n", INV_FLAG (EBT_VLAN_PRIO), info->prio, prio); } } /* * Checking Encapsulated Proto (Length/Type) field */ if (GET_BITMASK (EBT_VLAN_ENCAP)) { /* Is VLAN Encap parsed? */ EXIT_ON_MISMATCH (encap, EBT_VLAN_ENCAP); DEBUG_MSG ("matched encap=%s%2.4X for frame encap=%2.4X\n", INV_FLAG (EBT_VLAN_ENCAP), ntohs (info->encap), ntohs (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 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 ("params 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. Indicates that the tag header contains only user_priority information; * no VLAN identifier is present in the frame. This VID value shall not be * configured as a PVID, configured in any Filtering Database entry, or used in any * Management operation. * * 1 - The default Port VID (PVID) value used for classifying frames on ingress through a Bridge * Port. The PVID value can be changed by management on a per-Port basis. * * 0x0FFF - Reserved for implementation use. This VID value shall not be configured as a * PVID or transmitted in a tag header. * * The remaining values of VID are available for general use as VLAN identifiers. * A Bridge may implement the ability to support less than the full range of VID values; * i.e., for a given implementation, * an upper limit, N, is defined for the VID values supported, where N is less than or equal to 4094. * All implementations shall support the use of all VID values in the range 0 through their defined maximum * VID, N. * * For Linux, N = 4094. */ 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 > 4094) { /* check if id > than (0x0FFE) */ DEBUG_MSG ("vlan id %d is out of range (1-4094)\n", info->id); return -EINVAL; } /* * Note: This is valid VLAN-tagged frame point. * Any value of user_priority are acceptable, but could be ignored * according to 802.1Q Std. */ } else { /* * if id=0 (null VLAN ID) => Check for user_priority range */ 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; } } /* * Note2: This is valid priority-tagged frame point * with null VID field. */ } } else { /* VLAN Id not set */ if (GET_BITMASK (EBT_VLAN_PRIO)) { /* But user_priority is set - abnormal! */ info->id = 0; /* Set null VID (case for Priority-tagged frames) */ SET_BITMASK (EBT_VLAN_ID); /* and set id flag */ } } /* * Check for encapsulated proto range - it is possible to be any value for u_short range. * When relaying a tagged frame between 802.3/Ethernet MACs, * a Bridge may adjust the padding field such that * the minimum size of a transmitted tagged frame is 68 octets (7.2). * 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 packet length %d is less than minimal %d\n", ntohs (info->encap), ETH_ZLEN); return -EINVAL; } } /* * Otherwise is all correct */ DEBUG_MSG ("802.1Q tagged frame checked (%s table, %d hook)\n", tablename, hooknr); return 0; } static struct ebt_match filter_vlan = { {NULL, NULL}, EBT_VLAN_MATCH, ebt_filter_vlan, ebt_check_vlan, NULL, THIS_MODULE }; /* * Module initialization function. * Called when module is loaded to kernelspace */ 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 * Called when download module from kernelspace */ static void __exit fini (void) { ebt_unregister_match (&filter_vlan); } module_init (init); module_exit (fini); EXPORT_NO_SYMBOLS;