release/src-rt-6.x.4708/linux/linux-2.6.36/net/bridge/netfilter/ebt_vlan.c

   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
  29 #define MODULE_VERS "0.6"
  30
  31 MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
  32 MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
  33 MODULE_LICENSE("GPL");
  34
  35 #define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_
  36 #define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return false; }
  37
  38 static bool
  39 ebt_vlan_mt(const struct sk_buff *skb, struct xt_action_param *par)
  40 {
  41         const struct ebt_vlan_info *info = par->matchinfo;
  42         const struct vlan_hdr *fp;
  43         struct vlan_hdr _frame;
  44
  45         unsigned short TCI;     /* Whole TCI, given from parsed frame */
  46         unsigned short id;      /* VLAN ID, given from frame TCI */
  47         unsigned char prio;     /* user_priority, given from frame TCI */
  48         /* VLAN encapsulated Type/Length field, given from orig frame */
  49         __be16 encap;
  50
  51         fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame);
  52         if (fp == NULL)
  53                 return false;
  54
  55         /* Tag Control Information (TCI) consists of the following elements:
  56          * - User_priority. The user_priority field is three bits in length,
  57          * interpreted as a binary number.
  58          * - Canonical Format Indicator (CFI). The Canonical Format Indicator
  59          * (CFI) is a single bit flag value. Currently ignored.
  60          * - VLAN Identifier (VID). The VID is encoded as
  61          * an unsigned binary number. */
  62         TCI = ntohs(fp->h_vlan_TCI);
  63         id = TCI & VLAN_VID_MASK;
  64         prio = (TCI >> 13) & 0x7;
  65         encap = fp->h_vlan_encapsulated_proto;
  66
  67         /* Checking VLAN Identifier (VID) */
  68         if (GET_BITMASK(EBT_VLAN_ID))
  69                 EXIT_ON_MISMATCH(id, EBT_VLAN_ID);
  70
  71         /* Checking user_priority */
  72         if (GET_BITMASK(EBT_VLAN_PRIO))
  73                 EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO);
  74
  75         /* Checking Encapsulated Proto (Length/Type) field */
  76         if (GET_BITMASK(EBT_VLAN_ENCAP))
  77                 EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP);
  78
  79         return true;
  80 }
  81
  82 static int ebt_vlan_mt_check(const struct xt_mtchk_param *par)
  83 {
  84         struct ebt_vlan_info *info = par->matchinfo;
  85         const struct ebt_entry *e = par->entryinfo;
  86
  87         /* Is it 802.1Q frame checked? */
  88         if (e->ethproto != htons(ETH_P_8021Q)) {
  89                 pr_debug("passed entry proto %2.4X is not 802.1Q (8100)\n",
  90                          ntohs(e->ethproto));
  91                 return -EINVAL;
  92         }
  93
  94         /* Check for bitmask range
  95          * True if even one bit is out of mask */
  96         if (info->bitmask & ~EBT_VLAN_MASK) {
  97                 pr_debug("bitmask %2X is out of mask (%2X)\n",
  98                          info->bitmask, EBT_VLAN_MASK);
  99                 return -EINVAL;
 100         }
 101
 102         /* Check for inversion flags range */
 103         if (info->invflags & ~EBT_VLAN_MASK) {
 104                 pr_debug("inversion flags %2X is out of mask (%2X)\n",
 105                          info->invflags, EBT_VLAN_MASK);
 106                 return -EINVAL;
 107         }
 108
 109         /* Reserved VLAN ID (VID) values
 110          * -----------------------------
 111          * 0 - The null VLAN ID.
 112          * 1 - The default Port VID (PVID)
 113          * 0x0FFF - Reserved for implementation use.
 114          * if_vlan.h: VLAN_GROUP_ARRAY_LEN 4096. */
 115         if (GET_BITMASK(EBT_VLAN_ID)) {
 116                 if (!!info->id) { /* if id!=0 => check vid range */
 117                         if (info->id > VLAN_GROUP_ARRAY_LEN) {
 118                                 pr_debug("id %d is out of range (1-4096)\n",
 119                                          info->id);
 120                                 return -EINVAL;
 121                         }
 122                         /* Note: This is valid VLAN-tagged frame point.
 123                          * Any value of user_priority are acceptable,
 124                          * but should be ignored according to 802.1Q Std.
 125                          * So we just drop the prio flag. */
 126                         info->bitmask &= ~EBT_VLAN_PRIO;
 127                 }
 128                 /* Else, id=0 (null VLAN ID)  => user_priority range (any?) */
 129         }
 130
 131         if (GET_BITMASK(EBT_VLAN_PRIO)) {
 132                 if ((unsigned char) info->prio > 7) {
 133                         pr_debug("prio %d is out of range (0-7)\n",
 134                                  info->prio);
 135                         return -EINVAL;
 136                 }
 137         }
 138         /* Check for encapsulated proto range - it is possible to be
 139          * any value for u_short range.
 140          * if_ether.h:  ETH_ZLEN        60   -  Min. octets in frame sans FCS */
 141         if (GET_BITMASK(EBT_VLAN_ENCAP)) {
 142                 if ((unsigned short) ntohs(info->encap) < ETH_ZLEN) {
 143                         pr_debug("encap frame length %d is less than "
 144                                  "minimal\n", ntohs(info->encap));
 145                         return -EINVAL;
 146                 }
 147         }
 148
 149         return 0;
 150 }
 151
 152 static struct xt_match ebt_vlan_mt_reg __read_mostly = {
 153         .name           = "vlan",
 154         .revision       = 0,
 155         .family         = NFPROTO_BRIDGE,
 156         .match          = ebt_vlan_mt,
 157         .checkentry     = ebt_vlan_mt_check,
 158         .matchsize      = sizeof(struct ebt_vlan_info),
 159         .me             = THIS_MODULE,
 160 };
 161
 162 static int __init ebt_vlan_init(void)
 163 {
 164         pr_debug("ebtables 802.1Q extension module v" MODULE_VERS "\n");
 165         return xt_register_match(&ebt_vlan_mt_reg);
 166 }
 167
 168 static void __exit ebt_vlan_fini(void)
 169 {
 170         xt_unregister_match(&ebt_vlan_mt_reg);
 171 }
 172
 173 module_init(ebt_vlan_init);
 174 module_exit(ebt_vlan_fini);