]>
Commit | Line | Data |
---|---|---|
ecdfa446 GKH |
1 | /* |
2 | * Host AP crypt: host-based WEP encryption implementation for Host AP driver | |
3 | * | |
4 | * Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi> | |
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 version 2 as | |
8 | * published by the Free Software Foundation. See README and COPYING for | |
9 | * more details. | |
10 | */ | |
11 | ||
ecdfa446 GKH |
12 | #include <linux/module.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/random.h> | |
16 | #include <linux/skbuff.h> | |
a44325f9 | 17 | #include <linux/string.h> |
94a79942 | 18 | #include "rtllib.h" |
ecdfa446 | 19 | |
ecdfa446 | 20 | #include <linux/crypto.h> |
ecdfa446 | 21 | |
cb762154 | 22 | #include <linux/scatterlist.h> |
ecdfa446 | 23 | #include <linux/crc32.h> |
ecdfa446 GKH |
24 | |
25 | struct prism2_wep_data { | |
26 | u32 iv; | |
27 | #define WEP_KEY_LEN 13 | |
28 | u8 key[WEP_KEY_LEN + 1]; | |
29 | u8 key_len; | |
30 | u8 key_idx; | |
a44325f9 LF |
31 | struct crypto_blkcipher *tx_tfm; |
32 | struct crypto_blkcipher *rx_tfm; | |
ecdfa446 GKH |
33 | }; |
34 | ||
35 | ||
a44325f9 | 36 | static void *prism2_wep_init(int keyidx) |
ecdfa446 GKH |
37 | { |
38 | struct prism2_wep_data *priv; | |
39 | ||
929fa2a4 | 40 | priv = kzalloc(sizeof(*priv), GFP_ATOMIC); |
ecdfa446 GKH |
41 | if (priv == NULL) |
42 | goto fail; | |
ecdfa446 GKH |
43 | priv->key_idx = keyidx; |
44 | ||
ecdfa446 | 45 | priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); |
a44325f9 LF |
46 | if (IS_ERR(priv->tx_tfm)) { |
47 | printk(KERN_DEBUG "rtllib_crypt_wep: could not allocate " | |
48 | "crypto API arc4\n"); | |
49 | priv->tx_tfm = NULL; | |
50 | goto fail; | |
51 | } | |
52 | priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); | |
53 | if (IS_ERR(priv->rx_tfm)) { | |
54 | printk(KERN_DEBUG "rtllib_crypt_wep: could not allocate " | |
55 | "crypto API arc4\n"); | |
56 | priv->rx_tfm = NULL; | |
57 | goto fail; | |
58 | } | |
ecdfa446 GKH |
59 | |
60 | /* start WEP IV from a random value */ | |
61 | get_random_bytes(&priv->iv, 4); | |
62 | ||
63 | return priv; | |
64 | ||
65 | fail: | |
ecdfa446 | 66 | if (priv) { |
a44325f9 LF |
67 | if (priv->tx_tfm) |
68 | crypto_free_blkcipher(priv->tx_tfm); | |
69 | if (priv->rx_tfm) | |
70 | crypto_free_blkcipher(priv->rx_tfm); | |
71 | kfree(priv); | |
72 | } | |
ecdfa446 GKH |
73 | return NULL; |
74 | } | |
75 | ||
76 | ||
77 | static void prism2_wep_deinit(void *priv) | |
78 | { | |
79 | struct prism2_wep_data *_priv = priv; | |
cb762154 | 80 | |
ecdfa446 | 81 | if (_priv) { |
a44325f9 LF |
82 | if (_priv->tx_tfm) |
83 | crypto_free_blkcipher(_priv->tx_tfm); | |
84 | if (_priv->rx_tfm) | |
85 | crypto_free_blkcipher(_priv->rx_tfm); | |
86 | } | |
ecdfa446 GKH |
87 | kfree(priv); |
88 | } | |
89 | ||
90 | /* Perform WEP encryption on given skb that has at least 4 bytes of headroom | |
91 | * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted, | |
92 | * so the payload length increases with 8 bytes. | |
93 | * | |
94 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
95 | */ | |
96 | static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv) | |
97 | { | |
98 | struct prism2_wep_data *wep = priv; | |
99 | u32 klen, len; | |
100 | u8 key[WEP_KEY_LEN + 3]; | |
101 | u8 *pos; | |
a44325f9 LF |
102 | struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + |
103 | MAX_DEV_ADDR_SIZE); | |
ecdfa446 | 104 | struct blkcipher_desc desc = {.tfm = wep->tx_tfm}; |
ecdfa446 GKH |
105 | u32 crc; |
106 | u8 *icv; | |
107 | struct scatterlist sg; | |
108 | if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 || | |
94a79942 | 109 | skb->len < hdr_len){ |
a44325f9 LF |
110 | printk(KERN_ERR "Error!!! headroom=%d tailroom=%d skblen=%d" |
111 | " hdr_len=%d\n", skb_headroom(skb), skb_tailroom(skb), | |
112 | skb->len, hdr_len); | |
ecdfa446 | 113 | return -1; |
94a79942 | 114 | } |
ecdfa446 GKH |
115 | len = skb->len - hdr_len; |
116 | pos = skb_push(skb, 4); | |
117 | memmove(pos, pos + 4, hdr_len); | |
118 | pos += hdr_len; | |
119 | ||
120 | klen = 3 + wep->key_len; | |
121 | ||
122 | wep->iv++; | |
123 | ||
124 | /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key | |
125 | * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N) | |
126 | * can be used to speedup attacks, so avoid using them. */ | |
127 | if ((wep->iv & 0xff00) == 0xff00) { | |
128 | u8 B = (wep->iv >> 16) & 0xff; | |
129 | if (B >= 3 && B < klen) | |
130 | wep->iv += 0x0100; | |
131 | } | |
132 | ||
133 | /* Prepend 24-bit IV to RC4 key and TX frame */ | |
134 | *pos++ = key[0] = (wep->iv >> 16) & 0xff; | |
135 | *pos++ = key[1] = (wep->iv >> 8) & 0xff; | |
136 | *pos++ = key[2] = wep->iv & 0xff; | |
137 | *pos++ = wep->key_idx << 6; | |
138 | ||
139 | /* Copy rest of the WEP key (the secret part) */ | |
140 | memcpy(key + 3, wep->key, wep->key_len); | |
141 | ||
cb762154 | 142 | if (!tcb_desc->bHwSec) { |
ecdfa446 GKH |
143 | |
144 | /* Append little-endian CRC32 and encrypt it to produce ICV */ | |
ecdfa446 | 145 | crc = ~crc32_le(~0, pos, len); |
ecdfa446 GKH |
146 | icv = skb_put(skb, 4); |
147 | icv[0] = crc; | |
148 | icv[1] = crc >> 8; | |
149 | icv[2] = crc >> 16; | |
150 | icv[3] = crc >> 24; | |
151 | ||
ecdfa446 | 152 | sg_init_one(&sg, pos, len+4); |
94a79942 | 153 | crypto_blkcipher_setkey(wep->tx_tfm, key, klen); |
ecdfa446 | 154 | return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4); |
ecdfa446 GKH |
155 | } |
156 | ||
157 | return 0; | |
158 | } | |
159 | ||
160 | ||
a44325f9 LF |
161 | /* Perform WEP decryption on given struct buffer. Buffer includes whole WEP |
162 | * part of the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
ecdfa446 GKH |
163 | * ICV (4 bytes). len includes both IV and ICV. |
164 | * | |
165 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
166 | * failure. If frame is OK, IV and ICV will be removed. | |
167 | */ | |
168 | static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv) | |
169 | { | |
170 | struct prism2_wep_data *wep = priv; | |
171 | u32 klen, plen; | |
172 | u8 key[WEP_KEY_LEN + 3]; | |
173 | u8 keyidx, *pos; | |
a44325f9 LF |
174 | struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + |
175 | MAX_DEV_ADDR_SIZE); | |
ecdfa446 | 176 | struct blkcipher_desc desc = {.tfm = wep->rx_tfm}; |
ecdfa446 GKH |
177 | u32 crc; |
178 | u8 icv[4]; | |
179 | struct scatterlist sg; | |
180 | if (skb->len < hdr_len + 8) | |
181 | return -1; | |
182 | ||
183 | pos = skb->data + hdr_len; | |
184 | key[0] = *pos++; | |
185 | key[1] = *pos++; | |
186 | key[2] = *pos++; | |
187 | keyidx = *pos++ >> 6; | |
188 | if (keyidx != wep->key_idx) | |
189 | return -1; | |
190 | ||
191 | klen = 3 + wep->key_len; | |
192 | ||
193 | /* Copy rest of the WEP key (the secret part) */ | |
194 | memcpy(key + 3, wep->key, wep->key_len); | |
195 | ||
196 | /* Apply RC4 to data and compute CRC32 over decrypted data */ | |
197 | plen = skb->len - hdr_len - 8; | |
198 | ||
cb762154 | 199 | if (!tcb_desc->bHwSec) { |
ecdfa446 | 200 | sg_init_one(&sg, pos, plen+4); |
94a79942 | 201 | crypto_blkcipher_setkey(wep->rx_tfm, key, klen); |
ecdfa446 GKH |
202 | if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4)) |
203 | return -7; | |
ecdfa446 | 204 | crc = ~crc32_le(~0, pos, plen); |
ecdfa446 GKH |
205 | icv[0] = crc; |
206 | icv[1] = crc >> 8; | |
207 | icv[2] = crc >> 16; | |
208 | icv[3] = crc >> 24; | |
209 | if (memcmp(icv, pos + plen, 4) != 0) { | |
210 | /* ICV mismatch - drop frame */ | |
211 | return -2; | |
212 | } | |
213 | } | |
214 | /* Remove IV and ICV */ | |
215 | memmove(skb->data + 4, skb->data, hdr_len); | |
216 | skb_pull(skb, 4); | |
217 | skb_trim(skb, skb->len - 4); | |
218 | ||
219 | return 0; | |
220 | } | |
221 | ||
222 | ||
223 | static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv) | |
224 | { | |
225 | struct prism2_wep_data *wep = priv; | |
226 | ||
227 | if (len < 0 || len > WEP_KEY_LEN) | |
228 | return -1; | |
229 | ||
230 | memcpy(wep->key, key, len); | |
231 | wep->key_len = len; | |
232 | ||
233 | return 0; | |
234 | } | |
235 | ||
236 | ||
237 | static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv) | |
238 | { | |
239 | struct prism2_wep_data *wep = priv; | |
240 | ||
241 | if (len < wep->key_len) | |
242 | return -1; | |
243 | ||
244 | memcpy(key, wep->key, wep->key_len); | |
245 | ||
246 | return wep->key_len; | |
247 | } | |
248 | ||
249 | ||
a44325f9 | 250 | static char *prism2_wep_print_stats(char *p, void *priv) |
ecdfa446 GKH |
251 | { |
252 | struct prism2_wep_data *wep = priv; | |
253 | p += sprintf(p, "key[%d] alg=WEP len=%d\n", | |
254 | wep->key_idx, wep->key_len); | |
255 | return p; | |
256 | } | |
257 | ||
94a79942 | 258 | static struct rtllib_crypto_ops rtllib_crypt_wep = { |
ecdfa446 GKH |
259 | .name = "WEP", |
260 | .init = prism2_wep_init, | |
261 | .deinit = prism2_wep_deinit, | |
262 | .encrypt_mpdu = prism2_wep_encrypt, | |
263 | .decrypt_mpdu = prism2_wep_decrypt, | |
264 | .encrypt_msdu = NULL, | |
265 | .decrypt_msdu = NULL, | |
266 | .set_key = prism2_wep_set_key, | |
267 | .get_key = prism2_wep_get_key, | |
268 | .print_stats = prism2_wep_print_stats, | |
269 | .extra_prefix_len = 4, /* IV */ | |
270 | .extra_postfix_len = 4, /* ICV */ | |
271 | .owner = THIS_MODULE, | |
272 | }; | |
273 | ||
274 | ||
94a79942 | 275 | int __init rtllib_crypto_wep_init(void) |
ecdfa446 | 276 | { |
94a79942 | 277 | return rtllib_register_crypto_ops(&rtllib_crypt_wep); |
ecdfa446 GKH |
278 | } |
279 | ||
280 | ||
94a79942 | 281 | void __exit rtllib_crypto_wep_exit(void) |
ecdfa446 | 282 | { |
94a79942 | 283 | rtllib_unregister_crypto_ops(&rtllib_crypt_wep); |
ecdfa446 GKH |
284 | } |
285 | ||
d37e0208 SM |
286 | module_init(rtllib_crypto_wep_init); |
287 | module_exit(rtllib_crypto_wep_exit); | |
288 | ||
289 | MODULE_LICENSE("GPL"); |