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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)) | |
023a04be | 34 | return PTR_ERR(local->wep_tx_tfm); |
f0706e82 JB |
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); | |
023a04be | 40 | return PTR_ERR(local->wep_rx_tfm); |
f0706e82 JB |
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 | 86 | { |
70217d7f HH |
87 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
88 | unsigned int hdrlen; | |
f0706e82 JB |
89 | u8 *newhdr; |
90 | ||
70217d7f | 91 | hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
f0706e82 | 92 | |
23c0752a JB |
93 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
94 | skb_headroom(skb) < WEP_IV_LEN)) | |
95 | return NULL; | |
f0706e82 | 96 | |
70217d7f | 97 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
98 | newhdr = skb_push(skb, WEP_IV_LEN); |
99 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
100 | ieee80211_wep_get_iv(local, key, newhdr + hdrlen); | |
101 | return newhdr + hdrlen; | |
102 | } | |
103 | ||
104 | ||
4f0d18e2 JB |
105 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
106 | struct sk_buff *skb, | |
107 | struct ieee80211_key *key) | |
f0706e82 | 108 | { |
70217d7f HH |
109 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
110 | unsigned int hdrlen; | |
f0706e82 | 111 | |
70217d7f | 112 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
113 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); |
114 | skb_pull(skb, WEP_IV_LEN); | |
115 | } | |
116 | ||
117 | ||
118 | /* Perform WEP encryption using given key. data buffer must have tailroom | |
119 | * for 4-byte ICV. data_len must not include this ICV. Note: this function | |
120 | * does _not_ add IV. data = RC4(data | CRC32(data)) */ | |
121 | void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
122 | size_t klen, u8 *data, size_t data_len) | |
123 | { | |
124 | struct blkcipher_desc desc = { .tfm = tfm }; | |
125 | struct scatterlist sg; | |
126 | __le32 *icv; | |
127 | ||
128 | icv = (__le32 *)(data + data_len); | |
129 | *icv = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
130 | ||
131 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 132 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
133 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
134 | } | |
135 | ||
136 | ||
137 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
138 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
139 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
140 | * payload length increases with 8 bytes. | |
141 | * | |
142 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
143 | */ | |
144 | int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
145 | struct ieee80211_key *key) | |
146 | { | |
147 | u32 klen; | |
148 | u8 *rc4key, *iv; | |
149 | size_t len; | |
150 | ||
8f20fc24 | 151 | if (!key || key->conf.alg != ALG_WEP) |
f0706e82 JB |
152 | return -1; |
153 | ||
8f20fc24 | 154 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
155 | rc4key = kmalloc(klen, GFP_ATOMIC); |
156 | if (!rc4key) | |
157 | return -1; | |
158 | ||
159 | iv = ieee80211_wep_add_iv(local, skb, key); | |
160 | if (!iv) { | |
161 | kfree(rc4key); | |
162 | return -1; | |
163 | } | |
164 | ||
165 | len = skb->len - (iv + WEP_IV_LEN - skb->data); | |
166 | ||
167 | /* Prepend 24-bit IV to RC4 key */ | |
168 | memcpy(rc4key, iv, 3); | |
169 | ||
170 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 171 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
172 | |
173 | /* Add room for ICV */ | |
174 | skb_put(skb, WEP_ICV_LEN); | |
175 | ||
176 | ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen, | |
177 | iv + WEP_IV_LEN, len); | |
178 | ||
179 | kfree(rc4key); | |
180 | ||
181 | return 0; | |
182 | } | |
183 | ||
184 | ||
185 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
186 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
187 | * Return 0 on success and -1 on ICV mismatch. */ | |
188 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
189 | size_t klen, u8 *data, size_t data_len) | |
190 | { | |
191 | struct blkcipher_desc desc = { .tfm = tfm }; | |
192 | struct scatterlist sg; | |
193 | __le32 crc; | |
194 | ||
195 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 196 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
197 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
198 | ||
199 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
200 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
201 | /* ICV mismatch */ | |
202 | return -1; | |
203 | ||
204 | return 0; | |
205 | } | |
206 | ||
207 | ||
208 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
209 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
210 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
211 | * | |
212 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
213 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
214 | * is moved to the beginning of the skb and skb length will be reduced. | |
215 | */ | |
216 | int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
217 | struct ieee80211_key *key) | |
218 | { | |
219 | u32 klen; | |
220 | u8 *rc4key; | |
221 | u8 keyidx; | |
70217d7f HH |
222 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
223 | unsigned int hdrlen; | |
f0706e82 JB |
224 | size_t len; |
225 | int ret = 0; | |
226 | ||
70217d7f | 227 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
228 | return -1; |
229 | ||
70217d7f | 230 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
d2984872 | 231 | if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
f0706e82 JB |
232 | return -1; |
233 | ||
d2984872 | 234 | len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
f0706e82 JB |
235 | |
236 | keyidx = skb->data[hdrlen + 3] >> 6; | |
237 | ||
8f20fc24 | 238 | if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP) |
f0706e82 JB |
239 | return -1; |
240 | ||
8f20fc24 | 241 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
242 | |
243 | rc4key = kmalloc(klen, GFP_ATOMIC); | |
244 | if (!rc4key) | |
245 | return -1; | |
246 | ||
247 | /* Prepend 24-bit IV to RC4 key */ | |
248 | memcpy(rc4key, skb->data + hdrlen, 3); | |
249 | ||
250 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 251 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
252 | |
253 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
254 | skb->data + hdrlen + WEP_IV_LEN, | |
f4ea83dd | 255 | len)) |
f0706e82 | 256 | ret = -1; |
f0706e82 JB |
257 | |
258 | kfree(rc4key); | |
259 | ||
260 | /* Trim ICV */ | |
261 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
262 | ||
263 | /* Remove IV */ | |
264 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
265 | skb_pull(skb, WEP_IV_LEN); | |
266 | ||
267 | return ret; | |
268 | } | |
269 | ||
270 | ||
f0706e82 JB |
271 | u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
272 | { | |
70217d7f HH |
273 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
274 | unsigned int hdrlen; | |
f0706e82 JB |
275 | u8 *ivpos; |
276 | u32 iv; | |
277 | ||
70217d7f | 278 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
279 | return NULL; |
280 | ||
70217d7f | 281 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
282 | ivpos = skb->data + hdrlen; |
283 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
284 | ||
8f20fc24 | 285 | if (ieee80211_wep_weak_iv(iv, key->conf.keylen)) |
f0706e82 JB |
286 | return ivpos; |
287 | ||
288 | return NULL; | |
289 | } | |
4f0d18e2 | 290 | |
9ae54c84 | 291 | ieee80211_rx_result |
5cf121c3 | 292 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 | 293 | { |
358c8d9d HH |
294 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data; |
295 | ||
296 | if (!ieee80211_is_data(hdr->frame_control) && | |
297 | !ieee80211_is_auth(hdr->frame_control)) | |
9ae54c84 | 298 | return RX_CONTINUE; |
4f0d18e2 | 299 | |
5cf121c3 | 300 | if (!(rx->status->flag & RX_FLAG_DECRYPTED)) { |
f4ea83dd | 301 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) |
e4c26add | 302 | return RX_DROP_UNUSABLE; |
5cf121c3 | 303 | } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
304 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
305 | /* remove ICV */ | |
d2984872 | 306 | skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN); |
4f0d18e2 JB |
307 | } |
308 | ||
9ae54c84 | 309 | return RX_CONTINUE; |
4f0d18e2 | 310 | } |
6a22a59d | 311 | |
5cf121c3 | 312 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 313 | { |
e039fa4a JB |
314 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
315 | ||
6a22a59d JB |
316 | if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) { |
317 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key)) | |
318 | return -1; | |
319 | } else { | |
2b212141 | 320 | info->control.hw_key = &tx->key->conf; |
6a22a59d JB |
321 | if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) { |
322 | if (!ieee80211_wep_add_iv(tx->local, skb, tx->key)) | |
323 | return -1; | |
324 | } | |
325 | } | |
326 | return 0; | |
327 | } | |
328 | ||
9ae54c84 | 329 | ieee80211_tx_result |
5cf121c3 | 330 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 331 | { |
5cf121c3 | 332 | ieee80211_tx_set_protected(tx); |
6a22a59d JB |
333 | |
334 | if (wep_encrypt_skb(tx, tx->skb) < 0) { | |
335 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
9ae54c84 | 336 | return TX_DROP; |
6a22a59d JB |
337 | } |
338 | ||
5cf121c3 | 339 | if (tx->extra_frag) { |
6a22a59d | 340 | int i; |
5cf121c3 JB |
341 | for (i = 0; i < tx->num_extra_frag; i++) { |
342 | if (wep_encrypt_skb(tx, tx->extra_frag[i]) < 0) { | |
6a22a59d JB |
343 | I802_DEBUG_INC(tx->local-> |
344 | tx_handlers_drop_wep); | |
9ae54c84 | 345 | return TX_DROP; |
6a22a59d JB |
346 | } |
347 | } | |
348 | } | |
349 | ||
9ae54c84 | 350 | return TX_CONTINUE; |
6a22a59d | 351 | } |