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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 | ||
23c0752a JB |
96 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
97 | skb_headroom(skb) < WEP_IV_LEN)) | |
98 | return NULL; | |
f0706e82 JB |
99 | |
100 | hdrlen = ieee80211_get_hdrlen(fc); | |
101 | newhdr = skb_push(skb, WEP_IV_LEN); | |
102 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
103 | ieee80211_wep_get_iv(local, key, newhdr + hdrlen); | |
104 | return newhdr + hdrlen; | |
105 | } | |
106 | ||
107 | ||
4f0d18e2 JB |
108 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
109 | struct sk_buff *skb, | |
110 | struct ieee80211_key *key) | |
f0706e82 JB |
111 | { |
112 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
113 | u16 fc; | |
114 | int hdrlen; | |
115 | ||
116 | fc = le16_to_cpu(hdr->frame_control); | |
117 | hdrlen = ieee80211_get_hdrlen(fc); | |
118 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
119 | skb_pull(skb, WEP_IV_LEN); | |
120 | } | |
121 | ||
122 | ||
123 | /* Perform WEP encryption using given key. data buffer must have tailroom | |
124 | * for 4-byte ICV. data_len must not include this ICV. Note: this function | |
125 | * does _not_ add IV. data = RC4(data | CRC32(data)) */ | |
126 | void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
127 | size_t klen, u8 *data, size_t data_len) | |
128 | { | |
129 | struct blkcipher_desc desc = { .tfm = tfm }; | |
130 | struct scatterlist sg; | |
131 | __le32 *icv; | |
132 | ||
133 | icv = (__le32 *)(data + data_len); | |
134 | *icv = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
135 | ||
136 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 137 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
138 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
139 | } | |
140 | ||
141 | ||
142 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
143 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
144 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
145 | * payload length increases with 8 bytes. | |
146 | * | |
147 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
148 | */ | |
149 | int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
150 | struct ieee80211_key *key) | |
151 | { | |
152 | u32 klen; | |
153 | u8 *rc4key, *iv; | |
154 | size_t len; | |
155 | ||
8f20fc24 | 156 | if (!key || key->conf.alg != ALG_WEP) |
f0706e82 JB |
157 | return -1; |
158 | ||
8f20fc24 | 159 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
160 | rc4key = kmalloc(klen, GFP_ATOMIC); |
161 | if (!rc4key) | |
162 | return -1; | |
163 | ||
164 | iv = ieee80211_wep_add_iv(local, skb, key); | |
165 | if (!iv) { | |
166 | kfree(rc4key); | |
167 | return -1; | |
168 | } | |
169 | ||
170 | len = skb->len - (iv + WEP_IV_LEN - skb->data); | |
171 | ||
172 | /* Prepend 24-bit IV to RC4 key */ | |
173 | memcpy(rc4key, iv, 3); | |
174 | ||
175 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 176 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
177 | |
178 | /* Add room for ICV */ | |
179 | skb_put(skb, WEP_ICV_LEN); | |
180 | ||
181 | ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen, | |
182 | iv + WEP_IV_LEN, len); | |
183 | ||
184 | kfree(rc4key); | |
185 | ||
186 | return 0; | |
187 | } | |
188 | ||
189 | ||
190 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
191 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
192 | * Return 0 on success and -1 on ICV mismatch. */ | |
193 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
194 | size_t klen, u8 *data, size_t data_len) | |
195 | { | |
196 | struct blkcipher_desc desc = { .tfm = tfm }; | |
197 | struct scatterlist sg; | |
198 | __le32 crc; | |
199 | ||
200 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 201 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
202 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
203 | ||
204 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
205 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
206 | /* ICV mismatch */ | |
207 | return -1; | |
208 | ||
209 | return 0; | |
210 | } | |
211 | ||
212 | ||
213 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
214 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
215 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
216 | * | |
217 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
218 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
219 | * is moved to the beginning of the skb and skb length will be reduced. | |
220 | */ | |
221 | int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
222 | struct ieee80211_key *key) | |
223 | { | |
224 | u32 klen; | |
225 | u8 *rc4key; | |
226 | u8 keyidx; | |
227 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
228 | u16 fc; | |
229 | int hdrlen; | |
230 | size_t len; | |
231 | int ret = 0; | |
232 | ||
233 | fc = le16_to_cpu(hdr->frame_control); | |
234 | if (!(fc & IEEE80211_FCTL_PROTECTED)) | |
235 | return -1; | |
236 | ||
237 | hdrlen = ieee80211_get_hdrlen(fc); | |
238 | ||
239 | if (skb->len < 8 + hdrlen) | |
240 | return -1; | |
241 | ||
242 | len = skb->len - hdrlen - 8; | |
243 | ||
244 | keyidx = skb->data[hdrlen + 3] >> 6; | |
245 | ||
8f20fc24 | 246 | if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP) |
f0706e82 JB |
247 | return -1; |
248 | ||
8f20fc24 | 249 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
250 | |
251 | rc4key = kmalloc(klen, GFP_ATOMIC); | |
252 | if (!rc4key) | |
253 | return -1; | |
254 | ||
255 | /* Prepend 24-bit IV to RC4 key */ | |
256 | memcpy(rc4key, skb->data + hdrlen, 3); | |
257 | ||
258 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 259 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
260 | |
261 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
262 | skb->data + hdrlen + WEP_IV_LEN, | |
263 | len)) { | |
53cb4791 AG |
264 | if (net_ratelimit()) |
265 | printk(KERN_DEBUG "WEP decrypt failed (ICV)\n"); | |
f0706e82 JB |
266 | ret = -1; |
267 | } | |
268 | ||
269 | kfree(rc4key); | |
270 | ||
271 | /* Trim ICV */ | |
272 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
273 | ||
274 | /* Remove IV */ | |
275 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
276 | skb_pull(skb, WEP_IV_LEN); | |
277 | ||
278 | return ret; | |
279 | } | |
280 | ||
281 | ||
f0706e82 JB |
282 | u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
283 | { | |
284 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; | |
285 | u16 fc; | |
286 | int hdrlen; | |
287 | u8 *ivpos; | |
288 | u32 iv; | |
289 | ||
290 | fc = le16_to_cpu(hdr->frame_control); | |
291 | if (!(fc & IEEE80211_FCTL_PROTECTED)) | |
292 | return NULL; | |
293 | ||
294 | hdrlen = ieee80211_get_hdrlen(fc); | |
295 | ivpos = skb->data + hdrlen; | |
296 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
297 | ||
8f20fc24 | 298 | if (ieee80211_wep_weak_iv(iv, key->conf.keylen)) |
f0706e82 JB |
299 | return ivpos; |
300 | ||
301 | return NULL; | |
302 | } | |
4f0d18e2 | 303 | |
9ae54c84 | 304 | ieee80211_rx_result |
5cf121c3 | 305 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 JB |
306 | { |
307 | if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA && | |
308 | ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT || | |
309 | (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH)) | |
9ae54c84 | 310 | return RX_CONTINUE; |
4f0d18e2 | 311 | |
5cf121c3 | 312 | if (!(rx->status->flag & RX_FLAG_DECRYPTED)) { |
4f0d18e2 | 313 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) { |
7f3ad894 | 314 | #ifdef CONFIG_MAC80211_DEBUG |
4f0d18e2 JB |
315 | if (net_ratelimit()) |
316 | printk(KERN_DEBUG "%s: RX WEP frame, decrypt " | |
317 | "failed\n", rx->dev->name); | |
7f3ad894 | 318 | #endif /* CONFIG_MAC80211_DEBUG */ |
e4c26add | 319 | return RX_DROP_UNUSABLE; |
4f0d18e2 | 320 | } |
5cf121c3 | 321 | } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
322 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
323 | /* remove ICV */ | |
324 | skb_trim(rx->skb, rx->skb->len - 4); | |
325 | } | |
326 | ||
9ae54c84 | 327 | return RX_CONTINUE; |
4f0d18e2 | 328 | } |
6a22a59d | 329 | |
5cf121c3 | 330 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 331 | { |
e039fa4a JB |
332 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
333 | ||
334 | info->control.iv_len = WEP_IV_LEN; | |
335 | info->control.icv_len = WEP_ICV_LEN; | |
336 | ||
6a22a59d JB |
337 | if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) { |
338 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key)) | |
339 | return -1; | |
340 | } else { | |
2b212141 | 341 | info->control.hw_key = &tx->key->conf; |
6a22a59d JB |
342 | if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) { |
343 | if (!ieee80211_wep_add_iv(tx->local, skb, tx->key)) | |
344 | return -1; | |
345 | } | |
346 | } | |
347 | return 0; | |
348 | } | |
349 | ||
9ae54c84 | 350 | ieee80211_tx_result |
5cf121c3 | 351 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 352 | { |
5cf121c3 | 353 | ieee80211_tx_set_protected(tx); |
6a22a59d JB |
354 | |
355 | if (wep_encrypt_skb(tx, tx->skb) < 0) { | |
356 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
9ae54c84 | 357 | return TX_DROP; |
6a22a59d JB |
358 | } |
359 | ||
5cf121c3 | 360 | if (tx->extra_frag) { |
6a22a59d | 361 | int i; |
5cf121c3 JB |
362 | for (i = 0; i < tx->num_extra_frag; i++) { |
363 | if (wep_encrypt_skb(tx, tx->extra_frag[i]) < 0) { | |
6a22a59d JB |
364 | I802_DEBUG_INC(tx->local-> |
365 | tx_handlers_drop_wep); | |
9ae54c84 | 366 | return TX_DROP; |
6a22a59d JB |
367 | } |
368 | } | |
369 | } | |
370 | ||
9ae54c84 | 371 | return TX_CONTINUE; |
6a22a59d | 372 | } |