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