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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> |
860c6e6a | 20 | #include <asm/unaligned.h> |
f0706e82 JB |
21 | |
22 | #include <net/mac80211.h> | |
23 | #include "ieee80211_i.h" | |
24 | #include "wep.h" | |
25 | ||
26 | ||
27 | int ieee80211_wep_init(struct ieee80211_local *local) | |
28 | { | |
29 | /* start WEP IV from a random value */ | |
30 | get_random_bytes(&local->wep_iv, WEP_IV_LEN); | |
31 | ||
32 | local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
33 | CRYPTO_ALG_ASYNC); | |
34 | if (IS_ERR(local->wep_tx_tfm)) | |
023a04be | 35 | return PTR_ERR(local->wep_tx_tfm); |
f0706e82 JB |
36 | |
37 | local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
38 | CRYPTO_ALG_ASYNC); | |
39 | if (IS_ERR(local->wep_rx_tfm)) { | |
40 | crypto_free_blkcipher(local->wep_tx_tfm); | |
023a04be | 41 | return PTR_ERR(local->wep_rx_tfm); |
f0706e82 JB |
42 | } |
43 | ||
44 | return 0; | |
45 | } | |
46 | ||
47 | void ieee80211_wep_free(struct ieee80211_local *local) | |
48 | { | |
49 | crypto_free_blkcipher(local->wep_tx_tfm); | |
50 | crypto_free_blkcipher(local->wep_rx_tfm); | |
51 | } | |
52 | ||
c6a1fa12 | 53 | static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) |
f0706e82 | 54 | { |
c6a1fa12 JB |
55 | /* |
56 | * Fluhrer, Mantin, and Shamir have reported weaknesses in the | |
f0706e82 | 57 | * key scheduling algorithm of RC4. At least IVs (KeyByte + 3, |
c6a1fa12 JB |
58 | * 0xff, N) can be used to speedup attacks, so avoid using them. |
59 | */ | |
f0706e82 JB |
60 | if ((iv & 0xff00) == 0xff00) { |
61 | u8 B = (iv >> 16) & 0xff; | |
62 | if (B >= 3 && B < 3 + keylen) | |
c6a1fa12 | 63 | return true; |
f0706e82 | 64 | } |
c6a1fa12 | 65 | return false; |
f0706e82 JB |
66 | } |
67 | ||
68 | ||
4f0d18e2 JB |
69 | static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
70 | struct ieee80211_key *key, u8 *iv) | |
f0706e82 JB |
71 | { |
72 | local->wep_iv++; | |
8f20fc24 | 73 | if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen)) |
f0706e82 JB |
74 | local->wep_iv += 0x0100; |
75 | ||
76 | if (!iv) | |
77 | return; | |
78 | ||
79 | *iv++ = (local->wep_iv >> 16) & 0xff; | |
80 | *iv++ = (local->wep_iv >> 8) & 0xff; | |
81 | *iv++ = local->wep_iv & 0xff; | |
8f20fc24 | 82 | *iv++ = key->conf.keyidx << 6; |
f0706e82 JB |
83 | } |
84 | ||
85 | ||
6a22a59d JB |
86 | static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, |
87 | struct sk_buff *skb, | |
88 | struct ieee80211_key *key) | |
f0706e82 | 89 | { |
70217d7f HH |
90 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
91 | unsigned int hdrlen; | |
f0706e82 JB |
92 | u8 *newhdr; |
93 | ||
70217d7f | 94 | hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
f0706e82 | 95 | |
23c0752a JB |
96 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
97 | skb_headroom(skb) < WEP_IV_LEN)) | |
98 | return NULL; | |
f0706e82 | 99 | |
70217d7f | 100 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
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 | 111 | { |
70217d7f HH |
112 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
113 | unsigned int hdrlen; | |
f0706e82 | 114 | |
70217d7f | 115 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
116 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); |
117 | skb_pull(skb, WEP_IV_LEN); | |
118 | } | |
119 | ||
120 | ||
121 | /* Perform WEP encryption using given key. data buffer must have tailroom | |
122 | * for 4-byte ICV. data_len must not include this ICV. Note: this function | |
123 | * does _not_ add IV. data = RC4(data | CRC32(data)) */ | |
124 | void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
125 | size_t klen, u8 *data, size_t data_len) | |
126 | { | |
127 | struct blkcipher_desc desc = { .tfm = tfm }; | |
128 | struct scatterlist sg; | |
860c6e6a | 129 | __le32 icv; |
f0706e82 | 130 | |
860c6e6a IK |
131 | icv = cpu_to_le32(~crc32_le(~0, data, data_len)); |
132 | put_unaligned(icv, (__le32 *)(data + data_len)); | |
f0706e82 JB |
133 | |
134 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 135 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
136 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
137 | } | |
138 | ||
139 | ||
140 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
141 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
142 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
143 | * payload length increases with 8 bytes. | |
144 | * | |
145 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
146 | */ | |
147 | int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
148 | struct ieee80211_key *key) | |
149 | { | |
150 | u32 klen; | |
151 | u8 *rc4key, *iv; | |
152 | size_t len; | |
153 | ||
8f20fc24 | 154 | if (!key || key->conf.alg != ALG_WEP) |
f0706e82 JB |
155 | return -1; |
156 | ||
8f20fc24 | 157 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
158 | rc4key = kmalloc(klen, GFP_ATOMIC); |
159 | if (!rc4key) | |
160 | return -1; | |
161 | ||
162 | iv = ieee80211_wep_add_iv(local, skb, key); | |
163 | if (!iv) { | |
164 | kfree(rc4key); | |
165 | return -1; | |
166 | } | |
167 | ||
168 | len = skb->len - (iv + WEP_IV_LEN - skb->data); | |
169 | ||
170 | /* Prepend 24-bit IV to RC4 key */ | |
171 | memcpy(rc4key, iv, 3); | |
172 | ||
173 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 174 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
175 | |
176 | /* Add room for ICV */ | |
177 | skb_put(skb, WEP_ICV_LEN); | |
178 | ||
179 | ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen, | |
180 | iv + WEP_IV_LEN, len); | |
181 | ||
182 | kfree(rc4key); | |
183 | ||
184 | return 0; | |
185 | } | |
186 | ||
187 | ||
188 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
189 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
190 | * Return 0 on success and -1 on ICV mismatch. */ | |
191 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
192 | size_t klen, u8 *data, size_t data_len) | |
193 | { | |
194 | struct blkcipher_desc desc = { .tfm = tfm }; | |
195 | struct scatterlist sg; | |
196 | __le32 crc; | |
197 | ||
198 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 199 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
200 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
201 | ||
202 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
203 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
204 | /* ICV mismatch */ | |
205 | return -1; | |
206 | ||
207 | return 0; | |
208 | } | |
209 | ||
210 | ||
211 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
212 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
213 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
214 | * | |
215 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
216 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
217 | * is moved to the beginning of the skb and skb length will be reduced. | |
218 | */ | |
219 | int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, | |
220 | struct ieee80211_key *key) | |
221 | { | |
222 | u32 klen; | |
223 | u8 *rc4key; | |
224 | u8 keyidx; | |
70217d7f HH |
225 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
226 | unsigned int hdrlen; | |
f0706e82 JB |
227 | size_t len; |
228 | int ret = 0; | |
229 | ||
70217d7f | 230 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
231 | return -1; |
232 | ||
70217d7f | 233 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
d2984872 | 234 | if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
f0706e82 JB |
235 | return -1; |
236 | ||
d2984872 | 237 | len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
f0706e82 JB |
238 | |
239 | keyidx = skb->data[hdrlen + 3] >> 6; | |
240 | ||
8f20fc24 | 241 | if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP) |
f0706e82 JB |
242 | return -1; |
243 | ||
8f20fc24 | 244 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
245 | |
246 | rc4key = kmalloc(klen, GFP_ATOMIC); | |
247 | if (!rc4key) | |
248 | return -1; | |
249 | ||
250 | /* Prepend 24-bit IV to RC4 key */ | |
251 | memcpy(rc4key, skb->data + hdrlen, 3); | |
252 | ||
253 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 254 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
255 | |
256 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
257 | skb->data + hdrlen + WEP_IV_LEN, | |
f4ea83dd | 258 | len)) |
f0706e82 | 259 | ret = -1; |
f0706e82 JB |
260 | |
261 | kfree(rc4key); | |
262 | ||
263 | /* Trim ICV */ | |
264 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
265 | ||
266 | /* Remove IV */ | |
267 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
268 | skb_pull(skb, WEP_IV_LEN); | |
269 | ||
270 | return ret; | |
271 | } | |
272 | ||
273 | ||
c6a1fa12 | 274 | bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
f0706e82 | 275 | { |
70217d7f HH |
276 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
277 | unsigned int hdrlen; | |
f0706e82 JB |
278 | u8 *ivpos; |
279 | u32 iv; | |
280 | ||
70217d7f | 281 | if (!ieee80211_has_protected(hdr->frame_control)) |
c6a1fa12 | 282 | return false; |
f0706e82 | 283 | |
70217d7f | 284 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
285 | ivpos = skb->data + hdrlen; |
286 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
287 | ||
c6a1fa12 | 288 | return ieee80211_wep_weak_iv(iv, key->conf.keylen); |
f0706e82 | 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 | { |
c6a1fa12 JB |
332 | int i; |
333 | ||
5cf121c3 | 334 | ieee80211_tx_set_protected(tx); |
6a22a59d JB |
335 | |
336 | if (wep_encrypt_skb(tx, tx->skb) < 0) { | |
337 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
9ae54c84 | 338 | return TX_DROP; |
6a22a59d JB |
339 | } |
340 | ||
5cf121c3 | 341 | if (tx->extra_frag) { |
5cf121c3 | 342 | for (i = 0; i < tx->num_extra_frag; i++) { |
c6a1fa12 | 343 | if (wep_encrypt_skb(tx, tx->extra_frag[i])) { |
6a22a59d JB |
344 | I802_DEBUG_INC(tx->local-> |
345 | tx_handlers_drop_wep); | |
9ae54c84 | 346 | return TX_DROP; |
6a22a59d JB |
347 | } |
348 | } | |
349 | } | |
350 | ||
9ae54c84 | 351 | return TX_CONTINUE; |
6a22a59d | 352 | } |