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1ccea77e | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * Description: EBTables 802.1Q match extension kernelspace module. | |
4 | * Authors: Nick Fedchik <nick@fedchik.org.ua> | |
5 | * Bart De Schuymer <bdschuym@pandora.be> | |
1da177e4 LT |
6 | */ |
7 | ||
8 | #include <linux/if_ether.h> | |
9 | #include <linux/if_vlan.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/moduleparam.h> | |
18219d3f | 12 | #include <linux/netfilter/x_tables.h> |
1da177e4 LT |
13 | #include <linux/netfilter_bridge/ebtables.h> |
14 | #include <linux/netfilter_bridge/ebt_vlan.h> | |
15 | ||
1da177e4 LT |
16 | #define MODULE_VERS "0.6" |
17 | ||
1da177e4 | 18 | MODULE_AUTHOR("Nick Fedchik <nick@fedchik.org.ua>"); |
f776c4cd | 19 | MODULE_DESCRIPTION("Ebtables: 802.1Q VLAN tag match"); |
1da177e4 LT |
20 | MODULE_LICENSE("GPL"); |
21 | ||
1da177e4 | 22 | #define GET_BITMASK(_BIT_MASK_) info->bitmask & _BIT_MASK_ |
8cc784ee | 23 | #define EXIT_ON_MISMATCH(_MATCH_,_MASK_) {if (!((info->_MATCH_ == _MATCH_)^!!(info->invflags & _MASK_))) return false; } |
1da177e4 | 24 | |
8cc784ee | 25 | static bool |
62fc8051 | 26 | ebt_vlan_mt(const struct sk_buff *skb, struct xt_action_param *par) |
1da177e4 | 27 | { |
f7108a20 | 28 | const struct ebt_vlan_info *info = par->matchinfo; |
1da177e4 LT |
29 | |
30 | unsigned short TCI; /* Whole TCI, given from parsed frame */ | |
31 | unsigned short id; /* VLAN ID, given from frame TCI */ | |
32 | unsigned char prio; /* user_priority, given from frame TCI */ | |
33 | /* VLAN encapsulated Type/Length field, given from orig frame */ | |
47c183fa | 34 | __be16 encap; |
1da177e4 | 35 | |
df8a39de JP |
36 | if (skb_vlan_tag_present(skb)) { |
37 | TCI = skb_vlan_tag_get(skb); | |
13937911 JG |
38 | encap = skb->protocol; |
39 | } else { | |
40 | const struct vlan_hdr *fp; | |
41 | struct vlan_hdr _frame; | |
42 | ||
43 | fp = skb_header_pointer(skb, 0, sizeof(_frame), &_frame); | |
44 | if (fp == NULL) | |
45 | return false; | |
46 | ||
47 | TCI = ntohs(fp->h_vlan_TCI); | |
48 | encap = fp->h_vlan_encapsulated_proto; | |
49 | } | |
1da177e4 LT |
50 | |
51 | /* Tag Control Information (TCI) consists of the following elements: | |
52 | * - User_priority. The user_priority field is three bits in length, | |
53 | * interpreted as a binary number. | |
54 | * - Canonical Format Indicator (CFI). The Canonical Format Indicator | |
55 | * (CFI) is a single bit flag value. Currently ignored. | |
56 | * - VLAN Identifier (VID). The VID is encoded as | |
7f495ad9 IM |
57 | * an unsigned binary number. |
58 | */ | |
1da177e4 LT |
59 | id = TCI & VLAN_VID_MASK; |
60 | prio = (TCI >> 13) & 0x7; | |
1da177e4 LT |
61 | |
62 | /* Checking VLAN Identifier (VID) */ | |
63 | if (GET_BITMASK(EBT_VLAN_ID)) | |
64 | EXIT_ON_MISMATCH(id, EBT_VLAN_ID); | |
65 | ||
66 | /* Checking user_priority */ | |
67 | if (GET_BITMASK(EBT_VLAN_PRIO)) | |
68 | EXIT_ON_MISMATCH(prio, EBT_VLAN_PRIO); | |
69 | ||
70 | /* Checking Encapsulated Proto (Length/Type) field */ | |
71 | if (GET_BITMASK(EBT_VLAN_ENCAP)) | |
72 | EXIT_ON_MISMATCH(encap, EBT_VLAN_ENCAP); | |
73 | ||
8cc784ee | 74 | return true; |
1da177e4 LT |
75 | } |
76 | ||
b0f38452 | 77 | static int ebt_vlan_mt_check(const struct xt_mtchk_param *par) |
1da177e4 | 78 | { |
9b4fce7a JE |
79 | struct ebt_vlan_info *info = par->matchinfo; |
80 | const struct ebt_entry *e = par->entryinfo; | |
1da177e4 | 81 | |
1da177e4 LT |
82 | /* Is it 802.1Q frame checked? */ |
83 | if (e->ethproto != htons(ETH_P_8021Q)) { | |
ff67e4e4 JE |
84 | pr_debug("passed entry proto %2.4X is not 802.1Q (8100)\n", |
85 | ntohs(e->ethproto)); | |
bd414ee6 | 86 | return -EINVAL; |
1da177e4 LT |
87 | } |
88 | ||
89 | /* Check for bitmask range | |
7f495ad9 IM |
90 | * True if even one bit is out of mask |
91 | */ | |
1da177e4 | 92 | if (info->bitmask & ~EBT_VLAN_MASK) { |
ff67e4e4 JE |
93 | pr_debug("bitmask %2X is out of mask (%2X)\n", |
94 | info->bitmask, EBT_VLAN_MASK); | |
bd414ee6 | 95 | return -EINVAL; |
1da177e4 LT |
96 | } |
97 | ||
98 | /* Check for inversion flags range */ | |
99 | if (info->invflags & ~EBT_VLAN_MASK) { | |
ff67e4e4 JE |
100 | pr_debug("inversion flags %2X is out of mask (%2X)\n", |
101 | info->invflags, EBT_VLAN_MASK); | |
bd414ee6 | 102 | return -EINVAL; |
1da177e4 LT |
103 | } |
104 | ||
105 | /* Reserved VLAN ID (VID) values | |
106 | * ----------------------------- | |
9d6f229f | 107 | * 0 - The null VLAN ID. |
1da177e4 | 108 | * 1 - The default Port VID (PVID) |
9d6f229f | 109 | * 0x0FFF - Reserved for implementation use. |
7f495ad9 IM |
110 | * if_vlan.h: VLAN_N_VID 4096. |
111 | */ | |
1da177e4 LT |
112 | if (GET_BITMASK(EBT_VLAN_ID)) { |
113 | if (!!info->id) { /* if id!=0 => check vid range */ | |
b738127d | 114 | if (info->id > VLAN_N_VID) { |
ff67e4e4 JE |
115 | pr_debug("id %d is out of range (1-4096)\n", |
116 | info->id); | |
bd414ee6 | 117 | return -EINVAL; |
1da177e4 LT |
118 | } |
119 | /* Note: This is valid VLAN-tagged frame point. | |
9d6f229f | 120 | * Any value of user_priority are acceptable, |
1da177e4 | 121 | * but should be ignored according to 802.1Q Std. |
7f495ad9 IM |
122 | * So we just drop the prio flag. |
123 | */ | |
1da177e4 LT |
124 | info->bitmask &= ~EBT_VLAN_PRIO; |
125 | } | |
126 | /* Else, id=0 (null VLAN ID) => user_priority range (any?) */ | |
127 | } | |
128 | ||
129 | if (GET_BITMASK(EBT_VLAN_PRIO)) { | |
130 | if ((unsigned char) info->prio > 7) { | |
ff67e4e4 JE |
131 | pr_debug("prio %d is out of range (0-7)\n", |
132 | info->prio); | |
bd414ee6 | 133 | return -EINVAL; |
1da177e4 LT |
134 | } |
135 | } | |
136 | /* Check for encapsulated proto range - it is possible to be | |
137 | * any value for u_short range. | |
7f495ad9 IM |
138 | * if_ether.h: ETH_ZLEN 60 - Min. octets in frame sans FCS |
139 | */ | |
1da177e4 LT |
140 | if (GET_BITMASK(EBT_VLAN_ENCAP)) { |
141 | if ((unsigned short) ntohs(info->encap) < ETH_ZLEN) { | |
ff67e4e4 JE |
142 | pr_debug("encap frame length %d is less than " |
143 | "minimal\n", ntohs(info->encap)); | |
bd414ee6 | 144 | return -EINVAL; |
1da177e4 LT |
145 | } |
146 | } | |
147 | ||
bd414ee6 | 148 | return 0; |
1da177e4 LT |
149 | } |
150 | ||
043ef46c JE |
151 | static struct xt_match ebt_vlan_mt_reg __read_mostly = { |
152 | .name = "vlan", | |
001a18d3 JE |
153 | .revision = 0, |
154 | .family = NFPROTO_BRIDGE, | |
2d06d4a5 JE |
155 | .match = ebt_vlan_mt, |
156 | .checkentry = ebt_vlan_mt_check, | |
fc0e3df4 | 157 | .matchsize = sizeof(struct ebt_vlan_info), |
1da177e4 LT |
158 | .me = THIS_MODULE, |
159 | }; | |
160 | ||
65b4b4e8 | 161 | static int __init ebt_vlan_init(void) |
1da177e4 | 162 | { |
ff67e4e4 | 163 | pr_debug("ebtables 802.1Q extension module v" MODULE_VERS "\n"); |
043ef46c | 164 | return xt_register_match(&ebt_vlan_mt_reg); |
1da177e4 LT |
165 | } |
166 | ||
65b4b4e8 | 167 | static void __exit ebt_vlan_fini(void) |
1da177e4 | 168 | { |
043ef46c | 169 | xt_unregister_match(&ebt_vlan_mt_reg); |
1da177e4 LT |
170 | } |
171 | ||
65b4b4e8 AM |
172 | module_init(ebt_vlan_init); |
173 | module_exit(ebt_vlan_fini); |