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 static int debug;
30 #define MODULE_VERS "0.6"
31
32 module_param(debug, int, 0);
33 MODULE_PARM_DESC(debug, "debug=1 is turn on debug messages");
34 MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>");
35 MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match");
36 MODULE_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
43 static bool
ebt_vlan_mt(const struct sk_buff * skb,const struct xt_match_param * par)44 ebt_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
ebt_vlan_mt_check(const struct xt_mtchk_param * par)87 static 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
160 static 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
ebt_vlan_init(void)170 static 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
ebt_vlan_fini(void)178 static void __exit ebt_vlan_fini(void)
179 {
180 xt_unregister_match(&ebt_vlan_mt_reg);
181 }
182
183 module_init(ebt_vlan_init);
184 module_exit(ebt_vlan_fini);
185