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Commit | Line | Data |
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f0706e82 JB |
1 | /* |
2 | * Software WEP encryption implementation | |
3 | * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi> | |
4 | * Copyright 2003, Instant802 Networks, Inc. | |
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. | |
9 | */ | |
10 | ||
11 | #include <linux/netdevice.h> | |
12 | #include <linux/types.h> | |
13 | #include <linux/random.h> | |
14 | #include <linux/compiler.h> | |
15 | #include <linux/crc32.h> | |
16 | #include <linux/crypto.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/mm.h> | |
11763609 | 19 | #include <linux/scatterlist.h> |
f0706e82 JB |
20 | |
21 | #include <net/mac80211.h> | |
22 | #include "ieee80211_i.h" | |
23 | #include "wep.h" | |
24 | ||
25 | ||
26 | int ieee80211_wep_init(struct ieee80211_local *local) | |
27 | { | |
28 | /* start WEP IV from a random value */ | |
29 | get_random_bytes(&local->wep_iv, WEP_IV_LEN); | |
30 | ||
31 | local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
32 | CRYPTO_ALG_ASYNC); | |
33 | if (IS_ERR(local->wep_tx_tfm)) | |
34 | return -ENOMEM; | |
35 | ||
36 | local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
37 | CRYPTO_ALG_ASYNC); | |
38 | if (IS_ERR(local->wep_rx_tfm)) { | |
39 | crypto_free_blkcipher(local->wep_tx_tfm); | |
40 | return -ENOMEM; | |
41 | } | |
42 | ||
43 | return 0; | |
44 | } | |
45 | ||
46 | void ieee80211_wep_free(struct ieee80211_local *local) | |
47 | { | |
48 | crypto_free_blkcipher(local->wep_tx_tfm); | |
49 | crypto_free_blkcipher(local->wep_rx_tfm); | |
50 | } | |
51 | ||
52 | static inline int ieee80211_wep_weak_iv(u32 iv, int keylen) | |
53 | { | |
54 | /* Fluhrer, Mantin, and Shamir have reported weaknesses in the | |
55 | * key scheduling algorithm of RC4. At least IVs (KeyByte + 3, | |
56 | * 0xff, N) can be used to speedup attacks, so avoid using them. */ | |
57 | if ((iv & 0xff00) == 0xff00) { | |
58 | u8 B = (iv >> 16) & 0xff; | |
59 | if (B >= 3 && B < 3 + keylen) | |
60 | return 1; | |
61 | } | |
62 | return 0; | |
63 | } | |
64 | ||
65 | ||
4f0d18e2 JB |
66 | static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
67 | struct ieee80211_key *key, u8 *iv) | |
f0706e82 JB |
68 | { |
69 | local->wep_iv++; | |
8f20fc24 | 70 | if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen)) |
f0706e82 JB |
71 | local->wep_iv += 0x0100; |
72 | ||
73 | if (!iv) | |
74 | return; | |
75 | ||
76 | *iv++ = (local->wep_iv >> 16) & 0xff; | |
77 | *iv++ = (local->wep_iv >> 8) & 0xff; | |
78 | *iv++ = local->wep_iv & 0xff; | |
8f20fc24 | 79 | *iv++ = key->conf.keyidx << 6; |
f0706e82 JB |
80 | } |
81 | ||
82 | ||
6a22a59d JB |
83 | static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, |
84 | struct sk_buff *skb, | |
85 | struct ieee80211_key *key) | |
f0706e82 JB |
86 | { |
87 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
88 | u16 fc; | |
89 | int hdrlen; | |
90 | u8 *newhdr; | |
91 | ||
92 | fc = le16_to_cpu(hdr->frame_control); | |
93 | fc |= IEEE80211_FCTL_PROTECTED; | |
94 | hdr->frame_control = cpu_to_le16(fc); | |
95 | ||
96 | if ((skb_headroom(skb) < WEP_IV_LEN || | |
97 | skb_tailroom(skb) < WEP_ICV_LEN)) { | |
98 | I802_DEBUG_INC(local->tx_expand_skb_head); | |
99 | if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN, | |
100 | GFP_ATOMIC))) | |
101 | return NULL; | |
102 | } | |
103 | ||
104 | hdrlen = ieee80211_get_hdrlen(fc); | |
105 | newhdr = skb_push(skb, WEP_IV_LEN); | |
106 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
107 | ieee80211_wep_get_iv(local, key, newhdr + hdrlen); | |
108 | return newhdr + hdrlen; | |
109 | } | |
110 | ||
111 | ||
4f0d18e2 JB |
112 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
113 | struct sk_buff *skb, | |
114 | struct ieee80211_key *key) | |
f0706e82 JB |
115 | { |
116 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
117 | u16 fc; | |
118 | int hdrlen; | |
119 | ||
120 | fc = le16_to_cpu(hdr->frame_control); | |
121 | hdrlen = ieee80211_get_hdrlen(fc); | |
122 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
123 | skb_pull(skb, WEP_IV_LEN); | |
124 | } | |
125 | ||
126 | ||
127 | /* Perform WEP encryption using given key. data buffer must have tailroom | |
128 | * for 4-byte ICV. data_len must not include this ICV. Note: this function | |
129 | * does _not_ add IV. data = RC4(data | CRC32(data)) */ | |
130 | void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
131 | size_t klen, u8 *data, size_t data_len) | |
132 | { | |
133 | struct blkcipher_desc desc = { .tfm = tfm }; | |
134 | struct scatterlist sg; | |
135 | __le32 *icv; | |
136 | ||
137 | icv = (__le32 *)(data + data_len); | |
138 | *icv = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
139 | ||
140 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 141 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
142 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
143 | } | |
144 | ||
145 | ||
146 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
147 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
148 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
149 | * payload length increases with 8 bytes. | |
150 | * | |
151 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
152 | */ | |
153 | int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
154 | struct ieee80211_key *key) | |
155 | { | |
156 | u32 klen; | |
157 | u8 *rc4key, *iv; | |
158 | size_t len; | |
159 | ||
8f20fc24 | 160 | if (!key || key->conf.alg != ALG_WEP) |
f0706e82 JB |
161 | return -1; |
162 | ||
8f20fc24 | 163 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
164 | rc4key = kmalloc(klen, GFP_ATOMIC); |
165 | if (!rc4key) | |
166 | return -1; | |
167 | ||
168 | iv = ieee80211_wep_add_iv(local, skb, key); | |
169 | if (!iv) { | |
170 | kfree(rc4key); | |
171 | return -1; | |
172 | } | |
173 | ||
174 | len = skb->len - (iv + WEP_IV_LEN - skb->data); | |
175 | ||
176 | /* Prepend 24-bit IV to RC4 key */ | |
177 | memcpy(rc4key, iv, 3); | |
178 | ||
179 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 180 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
181 | |
182 | /* Add room for ICV */ | |
183 | skb_put(skb, WEP_ICV_LEN); | |
184 | ||
185 | ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen, | |
186 | iv + WEP_IV_LEN, len); | |
187 | ||
188 | kfree(rc4key); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | ||
194 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
195 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
196 | * Return 0 on success and -1 on ICV mismatch. */ | |
197 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
198 | size_t klen, u8 *data, size_t data_len) | |
199 | { | |
200 | struct blkcipher_desc desc = { .tfm = tfm }; | |
201 | struct scatterlist sg; | |
202 | __le32 crc; | |
203 | ||
204 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 205 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
206 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
207 | ||
208 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
209 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
210 | /* ICV mismatch */ | |
211 | return -1; | |
212 | ||
213 | return 0; | |
214 | } | |
215 | ||
216 | ||
217 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
218 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
219 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
220 | * | |
221 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
222 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
223 | * is moved to the beginning of the skb and skb length will be reduced. | |
224 | */ | |
225 | int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
226 | struct ieee80211_key *key) | |
227 | { | |
228 | u32 klen; | |
229 | u8 *rc4key; | |
230 | u8 keyidx; | |
231 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
232 | u16 fc; | |
233 | int hdrlen; | |
234 | size_t len; | |
235 | int ret = 0; | |
236 | ||
237 | fc = le16_to_cpu(hdr->frame_control); | |
238 | if (!(fc & IEEE80211_FCTL_PROTECTED)) | |
239 | return -1; | |
240 | ||
241 | hdrlen = ieee80211_get_hdrlen(fc); | |
242 | ||
243 | if (skb->len < 8 + hdrlen) | |
244 | return -1; | |
245 | ||
246 | len = skb->len - hdrlen - 8; | |
247 | ||
248 | keyidx = skb->data[hdrlen + 3] >> 6; | |
249 | ||
8f20fc24 | 250 | if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP) |
f0706e82 JB |
251 | return -1; |
252 | ||
8f20fc24 | 253 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
254 | |
255 | rc4key = kmalloc(klen, GFP_ATOMIC); | |
256 | if (!rc4key) | |
257 | return -1; | |
258 | ||
259 | /* Prepend 24-bit IV to RC4 key */ | |
260 | memcpy(rc4key, skb->data + hdrlen, 3); | |
261 | ||
262 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 263 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
264 | |
265 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
266 | skb->data + hdrlen + WEP_IV_LEN, | |
267 | len)) { | |
53cb4791 AG |
268 | if (net_ratelimit()) |
269 | printk(KERN_DEBUG "WEP decrypt failed (ICV)\n"); | |
f0706e82 JB |
270 | ret = -1; |
271 | } | |
272 | ||
273 | kfree(rc4key); | |
274 | ||
275 | /* Trim ICV */ | |
276 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
277 | ||
278 | /* Remove IV */ | |
279 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
280 | skb_pull(skb, WEP_IV_LEN); | |
281 | ||
282 | return ret; | |
283 | } | |
284 | ||
285 | ||
f0706e82 JB |
286 | u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
287 | { | |
288 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
289 | u16 fc; | |
290 | int hdrlen; | |
291 | u8 *ivpos; | |
292 | u32 iv; | |
293 | ||
294 | fc = le16_to_cpu(hdr->frame_control); | |
295 | if (!(fc & IEEE80211_FCTL_PROTECTED)) | |
296 | return NULL; | |
297 | ||
298 | hdrlen = ieee80211_get_hdrlen(fc); | |
299 | ivpos = skb->data + hdrlen; | |
300 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
301 | ||
8f20fc24 | 302 | if (ieee80211_wep_weak_iv(iv, key->conf.keylen)) |
f0706e82 JB |
303 | return ivpos; |
304 | ||
305 | return NULL; | |
306 | } | |
4f0d18e2 | 307 | |
9ae54c84 | 308 | ieee80211_rx_result |
5cf121c3 | 309 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 JB |
310 | { |
311 | if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA && | |
312 | ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT || | |
313 | (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH)) | |
9ae54c84 | 314 | return RX_CONTINUE; |
4f0d18e2 | 315 | |
5cf121c3 | 316 | if (!(rx->status->flag & RX_FLAG_DECRYPTED)) { |
4f0d18e2 | 317 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) { |
7f3ad894 | 318 | #ifdef CONFIG_MAC80211_DEBUG |
4f0d18e2 JB |
319 | if (net_ratelimit()) |
320 | printk(KERN_DEBUG "%s: RX WEP frame, decrypt " | |
321 | "failed\n", rx->dev->name); | |
7f3ad894 | 322 | #endif /* CONFIG_MAC80211_DEBUG */ |
e4c26add | 323 | return RX_DROP_UNUSABLE; |
4f0d18e2 | 324 | } |
5cf121c3 | 325 | } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
326 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
327 | /* remove ICV */ | |
328 | skb_trim(rx->skb, rx->skb->len - 4); | |
329 | } | |
330 | ||
9ae54c84 | 331 | return RX_CONTINUE; |
4f0d18e2 | 332 | } |
6a22a59d | 333 | |
5cf121c3 | 334 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 335 | { |
e039fa4a JB |
336 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
337 | ||
338 | info->control.iv_len = WEP_IV_LEN; | |
339 | info->control.icv_len = WEP_ICV_LEN; | |
340 | ||
6a22a59d | 341 | if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) { |
e039fa4a | 342 | info->control.hw_key = &tx->key->conf; |
6a22a59d JB |
343 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key)) |
344 | return -1; | |
345 | } else { | |
6a22a59d JB |
346 | if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) { |
347 | if (!ieee80211_wep_add_iv(tx->local, skb, tx->key)) | |
348 | return -1; | |
349 | } | |
350 | } | |
351 | return 0; | |
352 | } | |
353 | ||
9ae54c84 | 354 | ieee80211_tx_result |
5cf121c3 | 355 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 356 | { |
5cf121c3 | 357 | ieee80211_tx_set_protected(tx); |
6a22a59d JB |
358 | |
359 | if (wep_encrypt_skb(tx, tx->skb) < 0) { | |
360 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
9ae54c84 | 361 | return TX_DROP; |
6a22a59d JB |
362 | } |
363 | ||
5cf121c3 | 364 | if (tx->extra_frag) { |
6a22a59d | 365 | int i; |
5cf121c3 JB |
366 | for (i = 0; i < tx->num_extra_frag; i++) { |
367 | if (wep_encrypt_skb(tx, tx->extra_frag[i]) < 0) { | |
6a22a59d JB |
368 | I802_DEBUG_INC(tx->local-> |
369 | tx_handlers_drop_wep); | |
9ae54c84 | 370 | return TX_DROP; |
6a22a59d JB |
371 | } |
372 | } | |
373 | } | |
374 | ||
9ae54c84 | 375 | return TX_CONTINUE; |
6a22a59d | 376 | } |