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_bridge/ebtables.h>
  26 #include <linux/netfilter_bridge/ebt_vlan.h>
  27
  28 static int debug;
  29 #define MODULE_VERS "0.6"
  30
  31 module_param(debug, int, 0);
  32 MODULE_PARM_DESC(debug, "debug=1 is turn on debug messages");
  33 MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
  34 MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
  35 MODULE_LICENSE("GPL");
  36
  37
  38 #define DEBUG_MSG(args...) if (debug) printk (KERN_DEBUG "ebt_vlan: " args)
  39 #define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_
  40 #define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return EBT_NOMATCH;}
  41
  42 static int
  43 ebt_filter_vlan(const struct sk_buff *skb,
  44                 const struct net_device *in,
  45                 const struct net_device *out,
  46                 const void *data, unsigned int datalen)
  47 {
  48         const struct ebt_vlan_info *info = data;
  49         const struct vlan_hdr *fp;
  50         struct vlan_hdr _frame;
  51
  52         unsigned short TCI;     /* Whole TCI, given from parsed frame */
  53         unsigned short id;      /* VLAN ID, given from frame TCI */
  54         unsigned char prio;     /* user_priority, given from frame TCI */
  55         /* VLAN encapsulated Type/Length field, given from orig frame */
  56         __be16 encap;
  57
  58         fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame);
  59         if (fp == NULL)
  60                 return EBT_NOMATCH;
  61
  62         /* Tag Control Information (TCI) consists of the following elements:
  63          * - User_priority. The user_priority field is three bits in length,
  64          * interpreted as a binary number.
  65          * - Canonical Format Indicator (CFI). The Canonical Format Indicator
  66          * (CFI) is a single bit flag value. Currently ignored.
  67          * - VLAN Identifier (VID). The VID is encoded as
  68          * an unsigned binary number. */
  69         TCI = ntohs(fp->h_vlan_TCI);
  70         id = TCI & VLAN_VID_MASK;
  71         prio = (TCI >> 13) & 0x7;
  72         encap = fp->h_vlan_encapsulated_proto;
  73
  74         /* Checking VLAN Identifier (VID) */
  75         if (GET_BITMASK(EBT_VLAN_ID))
  76                 EXIT_ON_MISMATCH(id, EBT_VLAN_ID);
  77
  78         /* Checking user_priority */
  79         if (GET_BITMASK(EBT_VLAN_PRIO))
  80                 EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO);
  81
  82         /* Checking Encapsulated Proto (Length/Type) field */
  83         if (GET_BITMASK(EBT_VLAN_ENCAP))
  84                 EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP);
  85
  86         return EBT_MATCH;
  87 }
  88
  89 static int
  90 ebt_check_vlan(const char *tablename,
  91                unsigned int hooknr,
  92                const struct ebt_entry *e, void *data, unsigned int datalen)
  93 {
  94         struct ebt_vlan_info *info = data;
  95
  96         /* Parameters buffer overflow check */
  97         if (datalen != EBT_ALIGN(sizeof(struct ebt_vlan_info))) {
  98                 DEBUG_MSG
  99                     ("passed size %d is not eq to ebt_vlan_info (%Zd)\n",
 100                      datalen, sizeof(struct ebt_vlan_info));
 101                 return -EINVAL;
 102         }
 103
 104         /* Is it 802.1Q frame checked? */
 105         if (e->ethproto != htons(ETH_P_8021Q)) {
 106                 DEBUG_MSG
 107                     ("passed entry proto %2.4X is not 802.1Q (8100)\n",
 108                      (unsigned short) ntohs(e->ethproto));
 109                 return -EINVAL;
 110         }
 111
 112         /* Check for bitmask range
 113          * True if even one bit is out of mask */
 114         if (info->bitmask & ~EBT_VLAN_MASK) {
 115                 DEBUG_MSG("bitmask %2X is out of mask (%2X)\n",
 116                           info->bitmask, EBT_VLAN_MASK);
 117                 return -EINVAL;
 118         }
 119
 120         /* Check for inversion flags range */
 121         if (info->invflags & ~EBT_VLAN_MASK) {
 122                 DEBUG_MSG("inversion flags %2X is out of mask (%2X)\n",
 123                           info->invflags, EBT_VLAN_MASK);
 124                 return -EINVAL;
 125         }
 126
 127         /* Reserved VLAN ID (VID) values
 128          * -----------------------------
 129          * 0 - The null VLAN ID.
 130          * 1 - The default Port VID (PVID)
 131          * 0x0FFF - Reserved for implementation use.
 132          * if_vlan.h: VLAN_GROUP_ARRAY_LEN 4096. */
 133         if (GET_BITMASK(EBT_VLAN_ID)) {
 134                 if (!!info->id) { /* if id!=0 => check vid range */
 135                         if (info->id > VLAN_GROUP_ARRAY_LEN) {
 136                                 DEBUG_MSG
 137                                     ("id %d is out of range (1-4096)\n",
 138                                      info->id);
 139                                 return -EINVAL;
 140                         }
 141                         /* Note: This is valid VLAN-tagged frame point.
 142                          * Any value of user_priority are acceptable,
 143                          * but should be ignored according to 802.1Q Std.
 144                          * So we just drop the prio flag. */
 145                         info->bitmask &= ~EBT_VLAN_PRIO;
 146                 }
 147                 /* Else, id=0 (null VLAN ID)  => user_priority range (any?) */
 148         }
 149
 150         if (GET_BITMASK(EBT_VLAN_PRIO)) {
 151                 if ((unsigned char) info->prio > 7) {
 152                         DEBUG_MSG("prio %d is out of range (0-7)\n",
 153                              info->prio);
 154                         return -EINVAL;
 155                 }
 156         }
 157         /* Check for encapsulated proto range - it is possible to be
 158          * any value for u_short range.
 159          * if_ether.h:  ETH_ZLEN        60   -  Min. octets in frame sans FCS */
 160         if (GET_BITMASK(EBT_VLAN_ENCAP)) {
 161                 if ((unsigned short) ntohs(info->encap) < ETH_ZLEN) {
 162                         DEBUG_MSG
 163                             ("encap frame length %d is less than minimal\n",
 164                              ntohs(info->encap));
 165                         return -EINVAL;
 166                 }
 167         }
 168
 169         return 0;
 170 }
 171
 172 static struct ebt_match filter_vlan __read_mostly = {
 173         .name           = EBT_VLAN_MATCH,
 174         .match          = ebt_filter_vlan,
 175         .check          = ebt_check_vlan,
 176         .me             = THIS_MODULE,
 177 };
 178
 179 static int __init ebt_vlan_init(void)
 180 {
 181         DEBUG_MSG("ebtables 802.1Q extension module v"
 182                   MODULE_VERS "\n");
 183         DEBUG_MSG("module debug=%d\n", !!debug);
 184         return ebt_register_match(&filter_vlan);
 185 }
 186
 187 static void __exit ebt_vlan_fini(void)
 188 {
 189         ebt_unregister_match(&filter_vlan);
 190 }
 191
 192 module_init(ebt_vlan_init);
 193 module_exit(ebt_vlan_fini);