LXR linux/net/bridge/netfilter/ebt

   1/*
   2 * Description: EBTables 802.1Q match extension kernelspace module.
   3 * Authors: Nick Fedchik <nick@fedchik.org.ua>
   4 *          Bart De Schuymer <bdschuym@pandora.be>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19 */
  20
  21#include <linux/if_ether.h>
  22#include <linux/if_vlan.h>
  23#include <linux/module.h>
  24#include <linux/moduleparam.h>
  25#include <linux/netfilter/x_tables.h>
  26#include <linux/netfilter_bridge/ebtables.h>
  27#include <linux/netfilter_bridge/ebt_vlan.h>
  28
  29static int debug;
  30#define MODULE_VERS "0.6"
  31
  32module_param(debug, int, 0);
  33MODULE_PARM_DESC(debug, "debug=1 is turn on debug messages");
  34MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
  35MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
  36MODULE_LICENSE("GPL");
  37
  38
  39#define DEBUG_MSG(args...) if (debug) printk (KERN_DEBUG "ebt_vlan: " args)
  40#define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_
  41#define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return false; }
  42
  43static bool
  44ebt_vlan_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  45{
  46        const struct ebt_vlan_info *info = par->matchinfo;
  47        const struct vlan_hdr *fp;
  48        struct vlan_hdr _frame;
  49
  50        unsigned short TCI;     /* Whole TCI, given from parsed frame */
  51        unsigned short id;      /* VLAN ID, given from frame TCI */
  52        unsigned char prio;     /* user_priority, given from frame TCI */
  53        /* VLAN encapsulated Type/Length field, given from orig frame */
  54        __be16 encap;
  55
  56        fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame);
  57        if (fp == NULL)
  58                return false;
  59
  60        /* Tag Control Information (TCI) consists of the following elements:
  61         * - User_priority. The user_priority field is three bits in length,
  62         * interpreted as a binary number.
  63         * - Canonical Format Indicator (CFI). The Canonical Format Indicator
  64         * (CFI) is a single bit flag value. Currently ignored.
  65         * - VLAN Identifier (VID). The VID is encoded as
  66         * an unsigned binary number. */
  67        TCI = ntohs(fp->h_vlan_TCI);
  68        id = TCI & VLAN_VID_MASK;
  69        prio = (TCI >> 13) & 0x7;
  70        encap = fp->h_vlan_encapsulated_proto;
  71
  72        /* Checking VLAN Identifier (VID) */
  73        if (GET_BITMASK(EBT_VLAN_ID))
  74                EXIT_ON_MISMATCH(id, EBT_VLAN_ID);
  75
  76        /* Checking user_priority */
  77        if (GET_BITMASK(EBT_VLAN_PRIO))
  78                EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO);
  79
  80        /* Checking Encapsulated Proto (Length/Type) field */
  81        if (GET_BITMASK(EBT_VLAN_ENCAP))
  82                EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP);
  83
  84        return true;
  85}
  86
  87static bool ebt_vlan_mt_check(const struct xt_mtchk_param *par)
  88{
  89        struct ebt_vlan_info *info = par->matchinfo;
  90        const struct ebt_entry *e = par->entryinfo;
  91
  92        /* Is it 802.1Q frame checked? */
  93        if (e->ethproto != htons(ETH_P_8021Q)) {
  94                DEBUG_MSG
  95                    ("passed entry proto %2.4X is not 802.1Q (8100)\n",
  96                     (unsigned short) ntohs(e->ethproto));
  97                return false;
  98        }
  99
 100        /* Check for bitmask range
 101         * True if even one bit is out of mask */
 102        if (info->bitmask & ~EBT_VLAN_MASK) {
 103                DEBUG_MSG("bitmask %2X is out of mask (%2X)\n",
 104                          info->bitmask, EBT_VLAN_MASK);
 105                return false;
 106        }
 107
 108        /* Check for inversion flags range */
 109        if (info->invflags & ~EBT_VLAN_MASK) {
 110                DEBUG_MSG("inversion flags %2X is out of mask (%2X)\n",
 111                          info->invflags, EBT_VLAN_MASK);
 112                return false;
 113        }
 114
 115        /* Reserved VLAN ID (VID) values
 116         * -----------------------------
 117         * 0 - The null VLAN ID.
 118         * 1 - The default Port VID (PVID)
 119         * 0x0FFF - Reserved for implementation use.
 120         * if_vlan.h: VLAN_GROUP_ARRAY_LEN 4096. */
 121        if (GET_BITMASK(EBT_VLAN_ID)) {
 122                if (!!info->id) { /* if id!=0 => check vid range */
 123                        if (info->id > VLAN_GROUP_ARRAY_LEN) {
 124                                DEBUG_MSG
 125                                    ("id %d is out of range (1-4096)\n",
 126                                     info->id);
 127                                return false;
 128                        }
 129                        /* Note: This is valid VLAN-tagged frame point.
 130                         * Any value of user_priority are acceptable,
 131                         * but should be ignored according to 802.1Q Std.
 132                         * So we just drop the prio flag. */
 133                        info->bitmask &= ~EBT_VLAN_PRIO;
 134                }
 135                /* Else, id=0 (null VLAN ID)  => user_priority range (any?) */
 136        }
 137
 138        if (GET_BITMASK(EBT_VLAN_PRIO)) {
 139                if ((unsigned char) info->prio > 7) {
 140                        DEBUG_MSG("prio %d is out of range (0-7)\n",
 141                             info->prio);
 142                        return false;
 143                }
 144        }
 145        /* Check for encapsulated proto range - it is possible to be
 146         * any value for u_short range.
 147         * if_ether.h:  ETH_ZLEN        60   -  Min. octets in frame sans FCS */
 148        if (GET_BITMASK(EBT_VLAN_ENCAP)) {
 149                if ((unsigned short) ntohs(info->encap) < ETH_ZLEN) {
 150                        DEBUG_MSG
 151                            ("encap frame length %d is less than minimal\n",
 152                             ntohs(info->encap));
 153                        return false;
 154                }
 155        }
 156
 157        return true;
 158}
 159
 160static struct xt_match ebt_vlan_mt_reg __read_mostly = {
 161        .name           = "vlan",
 162        .revision       = 0,
 163        .family         = NFPROTO_BRIDGE,
 164        .match          = ebt_vlan_mt,
 165        .checkentry     = ebt_vlan_mt_check,
 166        .matchsize      = XT_ALIGN(sizeof(struct ebt_vlan_info)),
 167        .me             = THIS_MODULE,
 168};
 169
 170static int __init ebt_vlan_init(void)
 171{
 172        DEBUG_MSG("ebtables 802.1Q extension module v"
 173                  MODULE_VERS "\n");
 174        DEBUG_MSG("module debug=%d\n", !!debug);
 175        return xt_register_match(&ebt_vlan_mt_reg);
 176}
 177
 178static void __exit ebt_vlan_fini(void)
 179{
 180        xt_unregister_match(&ebt_vlan_mt_reg);
 181}
 182
 183module_init(ebt_vlan_init);
 184module_exit(ebt_vlan_fini);
 185