diff options
Diffstat (limited to 'net/bridge/netfilter/ebt_vlan.c')
| -rw-r--r-- | net/bridge/netfilter/ebt_vlan.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_vlan.c b/net/bridge/netfilter/ebt_vlan.c new file mode 100644 index 00000000..eae67bf0 --- /dev/null +++ b/net/bridge/netfilter/ebt_vlan.c @@ -0,0 +1,181 @@ +/* + * Description: EBTables 802.1Q match extension kernelspace module. + * Authors: Nick Fedchik <nick@fedchik.org.ua> + * Bart De Schuymer <bdschuym@pandora.be> + * + * 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 <linux/if_ether.h> +#include <linux/if_vlan.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_bridge/ebtables.h> +#include <linux/netfilter_bridge/ebt_vlan.h> + +#define MODULE_VERS "0.6" + +MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>"); +MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match"); +MODULE_LICENSE("GPL"); + +#define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_ +#define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return false; } + +static bool +ebt_vlan_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct ebt_vlan_info *info = par->matchinfo; + + 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 */ + /* VLAN encapsulated Type/Length field, given from orig frame */ + __be16 encap; + + if (vlan_tx_tag_present(skb)) { + TCI = vlan_tx_tag_get(skb); + encap = skb->protocol; + } else { + const struct vlan_hdr *fp; + struct vlan_hdr _frame; + + fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame); + if (fp == NULL) + return false; + + TCI = ntohs(fp->h_vlan_TCI); + encap = fp->h_vlan_encapsulated_proto; + } + + /* Tag Control Information (TCI) consists of the following elements: + * - User_priority. The user_priority field is three bits in length, + * interpreted as a binary number. + * - Canonical Format Indicator (CFI). The Canonical Format Indicator + * (CFI) is a single bit flag value. Currently ignored. + * - VLAN Identifier (VID). The VID is encoded as + * an unsigned binary number. */ + id = TCI & VLAN_VID_MASK; + prio = (TCI >> 13) & 0x7; + + /* Checking VLAN Identifier (VID) */ + if (GET_BITMASK(EBT_VLAN_ID)) + EXIT_ON_MISMATCH(id, EBT_VLAN_ID); + + /* Checking user_priority */ + if (GET_BITMASK(EBT_VLAN_PRIO)) + EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO); + + /* Checking Encapsulated Proto (Length/Type) field */ + if (GET_BITMASK(EBT_VLAN_ENCAP)) + EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP); + + return true; +} + +static int ebt_vlan_mt_check(const struct xt_mtchk_param *par) +{ + struct ebt_vlan_info *info = par->matchinfo; + const struct ebt_entry *e = par->entryinfo; + + /* Is it 802.1Q frame checked? */ + if (e->ethproto != htons(ETH_P_8021Q)) { + pr_debug("passed entry proto %2.4X is not 802.1Q (8100)\n", + ntohs(e->ethproto)); + return -EINVAL; + } + + /* Check for bitmask range + * True if even one bit is out of mask */ + if (info->bitmask & ~EBT_VLAN_MASK) { + pr_debug("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) { + pr_debug("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. + * 1 - The default Port VID (PVID) + * 0x0FFF - Reserved for implementation use. + * if_vlan.h: VLAN_N_VID 4096. */ + if (GET_BITMASK(EBT_VLAN_ID)) { + if (!!info->id) { /* if id!=0 => check vid range */ + if (info->id > VLAN_N_VID) { + pr_debug("id %d is out of range (1-4096)\n", + info->id); + return -EINVAL; + } + /* Note: This is valid VLAN-tagged frame point. + * Any value of user_priority are acceptable, + * but should be ignored according to 802.1Q Std. + * So we just drop the prio flag. */ + info->bitmask &= ~EBT_VLAN_PRIO; + } + /* Else, id=0 (null VLAN ID) => user_priority range (any?) */ + } + + if (GET_BITMASK(EBT_VLAN_PRIO)) { + if ((unsigned char) info->prio > 7) { + pr_debug("prio %d is out of range (0-7)\n", + info->prio); + return -EINVAL; + } + } + /* Check for encapsulated proto range - it is possible to be + * any value for u_short range. + * 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) { + pr_debug("encap frame length %d is less than " + "minimal\n", ntohs(info->encap)); + return -EINVAL; + } + } + + return 0; +} + +static struct xt_match ebt_vlan_mt_reg __read_mostly = { + .name = "vlan", + .revision = 0, + .family = NFPROTO_BRIDGE, + .match = ebt_vlan_mt, + .checkentry = ebt_vlan_mt_check, + .matchsize = sizeof(struct ebt_vlan_info), + .me = THIS_MODULE, +}; + +static int __init ebt_vlan_init(void) +{ + pr_debug("ebtables 802.1Q extension module v" MODULE_VERS "\n"); + return xt_register_match(&ebt_vlan_mt_reg); +} + +static void __exit ebt_vlan_fini(void) +{ + xt_unregister_match(&ebt_vlan_mt_reg); +} + +module_init(ebt_vlan_init); +module_exit(ebt_vlan_fini); |