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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> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
860c6e6a | 21 | #include <asm/unaligned.h> |
f0706e82 JB |
22 | |
23 | #include <net/mac80211.h> | |
24 | #include "ieee80211_i.h" | |
25 | #include "wep.h" | |
26 | ||
27 | ||
28 | int ieee80211_wep_init(struct ieee80211_local *local) | |
29 | { | |
30 | /* start WEP IV from a random value */ | |
31 | get_random_bytes(&local->wep_iv, WEP_IV_LEN); | |
32 | ||
33 | local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
34 | CRYPTO_ALG_ASYNC); | |
35 | if (IS_ERR(local->wep_tx_tfm)) | |
023a04be | 36 | return PTR_ERR(local->wep_tx_tfm); |
f0706e82 JB |
37 | |
38 | local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
39 | CRYPTO_ALG_ASYNC); | |
40 | if (IS_ERR(local->wep_rx_tfm)) { | |
41 | crypto_free_blkcipher(local->wep_tx_tfm); | |
023a04be | 42 | return PTR_ERR(local->wep_rx_tfm); |
f0706e82 JB |
43 | } |
44 | ||
45 | return 0; | |
46 | } | |
47 | ||
48 | void ieee80211_wep_free(struct ieee80211_local *local) | |
49 | { | |
50 | crypto_free_blkcipher(local->wep_tx_tfm); | |
51 | crypto_free_blkcipher(local->wep_rx_tfm); | |
52 | } | |
53 | ||
c6a1fa12 | 54 | static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) |
f0706e82 | 55 | { |
c6a1fa12 JB |
56 | /* |
57 | * Fluhrer, Mantin, and Shamir have reported weaknesses in the | |
f0706e82 | 58 | * key scheduling algorithm of RC4. At least IVs (KeyByte + 3, |
c6a1fa12 JB |
59 | * 0xff, N) can be used to speedup attacks, so avoid using them. |
60 | */ | |
f0706e82 JB |
61 | if ((iv & 0xff00) == 0xff00) { |
62 | u8 B = (iv >> 16) & 0xff; | |
63 | if (B >= 3 && B < 3 + keylen) | |
c6a1fa12 | 64 | return true; |
f0706e82 | 65 | } |
c6a1fa12 | 66 | return false; |
f0706e82 JB |
67 | } |
68 | ||
69 | ||
4f0d18e2 | 70 | static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
c9cf0122 | 71 | int keylen, int keyidx, u8 *iv) |
f0706e82 JB |
72 | { |
73 | local->wep_iv++; | |
c9cf0122 | 74 | if (ieee80211_wep_weak_iv(local->wep_iv, keylen)) |
f0706e82 JB |
75 | local->wep_iv += 0x0100; |
76 | ||
77 | if (!iv) | |
78 | return; | |
79 | ||
80 | *iv++ = (local->wep_iv >> 16) & 0xff; | |
81 | *iv++ = (local->wep_iv >> 8) & 0xff; | |
82 | *iv++ = local->wep_iv & 0xff; | |
c9cf0122 | 83 | *iv++ = keyidx << 6; |
f0706e82 JB |
84 | } |
85 | ||
86 | ||
6a22a59d JB |
87 | static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, |
88 | struct sk_buff *skb, | |
c9cf0122 | 89 | int keylen, int keyidx) |
f0706e82 | 90 | { |
70217d7f HH |
91 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
92 | unsigned int hdrlen; | |
f0706e82 JB |
93 | u8 *newhdr; |
94 | ||
70217d7f | 95 | hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
f0706e82 | 96 | |
23c0752a JB |
97 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
98 | skb_headroom(skb) < WEP_IV_LEN)) | |
99 | return NULL; | |
f0706e82 | 100 | |
70217d7f | 101 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
102 | newhdr = skb_push(skb, WEP_IV_LEN); |
103 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
c9cf0122 | 104 | ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen); |
f0706e82 JB |
105 | return newhdr + hdrlen; |
106 | } | |
107 | ||
108 | ||
4f0d18e2 JB |
109 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
110 | struct sk_buff *skb, | |
111 | struct ieee80211_key *key) | |
f0706e82 | 112 | { |
70217d7f HH |
113 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
114 | unsigned int hdrlen; | |
f0706e82 | 115 | |
70217d7f | 116 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
117 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); |
118 | skb_pull(skb, WEP_IV_LEN); | |
119 | } | |
120 | ||
121 | ||
122 | /* Perform WEP encryption using given key. data buffer must have tailroom | |
123 | * for 4-byte ICV. data_len must not include this ICV. Note: this function | |
124 | * does _not_ add IV. data = RC4(data | CRC32(data)) */ | |
125 | void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
126 | size_t klen, u8 *data, size_t data_len) | |
127 | { | |
128 | struct blkcipher_desc desc = { .tfm = tfm }; | |
129 | struct scatterlist sg; | |
860c6e6a | 130 | __le32 icv; |
f0706e82 | 131 | |
860c6e6a IK |
132 | icv = cpu_to_le32(~crc32_le(~0, data, data_len)); |
133 | put_unaligned(icv, (__le32 *)(data + data_len)); | |
f0706e82 JB |
134 | |
135 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 136 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
137 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
138 | } | |
139 | ||
140 | ||
141 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
142 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
143 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
144 | * payload length increases with 8 bytes. | |
145 | * | |
146 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
147 | */ | |
fffd0934 JB |
148 | int ieee80211_wep_encrypt(struct ieee80211_local *local, |
149 | struct sk_buff *skb, | |
150 | const u8 *key, int keylen, int keyidx) | |
f0706e82 | 151 | { |
c9cf0122 | 152 | u8 *iv; |
f0706e82 | 153 | size_t len; |
c9cf0122 | 154 | u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
f0706e82 | 155 | |
c9cf0122 JB |
156 | iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); |
157 | if (!iv) | |
f0706e82 | 158 | return -1; |
f0706e82 JB |
159 | |
160 | len = skb->len - (iv + WEP_IV_LEN - skb->data); | |
161 | ||
162 | /* Prepend 24-bit IV to RC4 key */ | |
163 | memcpy(rc4key, iv, 3); | |
164 | ||
165 | /* Copy rest of the WEP key (the secret part) */ | |
c9cf0122 | 166 | memcpy(rc4key + 3, key, keylen); |
f0706e82 JB |
167 | |
168 | /* Add room for ICV */ | |
169 | skb_put(skb, WEP_ICV_LEN); | |
170 | ||
c9cf0122 | 171 | ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3, |
f0706e82 JB |
172 | iv + WEP_IV_LEN, len); |
173 | ||
f0706e82 JB |
174 | return 0; |
175 | } | |
176 | ||
177 | ||
178 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
179 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
180 | * Return 0 on success and -1 on ICV mismatch. */ | |
181 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
182 | size_t klen, u8 *data, size_t data_len) | |
183 | { | |
184 | struct blkcipher_desc desc = { .tfm = tfm }; | |
185 | struct scatterlist sg; | |
186 | __le32 crc; | |
187 | ||
188 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 189 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
190 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
191 | ||
192 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
193 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
194 | /* ICV mismatch */ | |
195 | return -1; | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
200 | ||
201 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
202 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
203 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
204 | * | |
205 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
206 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
207 | * is moved to the beginning of the skb and skb length will be reduced. | |
208 | */ | |
c9cf0122 JB |
209 | static int ieee80211_wep_decrypt(struct ieee80211_local *local, |
210 | struct sk_buff *skb, | |
211 | struct ieee80211_key *key) | |
f0706e82 JB |
212 | { |
213 | u32 klen; | |
214 | u8 *rc4key; | |
215 | u8 keyidx; | |
70217d7f HH |
216 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
217 | unsigned int hdrlen; | |
f0706e82 JB |
218 | size_t len; |
219 | int ret = 0; | |
220 | ||
70217d7f | 221 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
222 | return -1; |
223 | ||
70217d7f | 224 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
d2984872 | 225 | if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
f0706e82 JB |
226 | return -1; |
227 | ||
d2984872 | 228 | len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
f0706e82 JB |
229 | |
230 | keyidx = skb->data[hdrlen + 3] >> 6; | |
231 | ||
8f20fc24 | 232 | if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP) |
f0706e82 JB |
233 | return -1; |
234 | ||
8f20fc24 | 235 | klen = 3 + key->conf.keylen; |
f0706e82 JB |
236 | |
237 | rc4key = kmalloc(klen, GFP_ATOMIC); | |
238 | if (!rc4key) | |
239 | return -1; | |
240 | ||
241 | /* Prepend 24-bit IV to RC4 key */ | |
242 | memcpy(rc4key, skb->data + hdrlen, 3); | |
243 | ||
244 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 245 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
246 | |
247 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
248 | skb->data + hdrlen + WEP_IV_LEN, | |
f4ea83dd | 249 | len)) |
f0706e82 | 250 | ret = -1; |
f0706e82 JB |
251 | |
252 | kfree(rc4key); | |
253 | ||
254 | /* Trim ICV */ | |
255 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
256 | ||
257 | /* Remove IV */ | |
258 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
259 | skb_pull(skb, WEP_IV_LEN); | |
260 | ||
261 | return ret; | |
262 | } | |
263 | ||
264 | ||
c6a1fa12 | 265 | bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
f0706e82 | 266 | { |
70217d7f HH |
267 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
268 | unsigned int hdrlen; | |
f0706e82 JB |
269 | u8 *ivpos; |
270 | u32 iv; | |
271 | ||
70217d7f | 272 | if (!ieee80211_has_protected(hdr->frame_control)) |
c6a1fa12 | 273 | return false; |
f0706e82 | 274 | |
70217d7f | 275 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
276 | ivpos = skb->data + hdrlen; |
277 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
278 | ||
c6a1fa12 | 279 | return ieee80211_wep_weak_iv(iv, key->conf.keylen); |
f0706e82 | 280 | } |
4f0d18e2 | 281 | |
9ae54c84 | 282 | ieee80211_rx_result |
5cf121c3 | 283 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 | 284 | { |
eb9fb5b8 JB |
285 | struct sk_buff *skb = rx->skb; |
286 | struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); | |
287 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; | |
358c8d9d HH |
288 | |
289 | if (!ieee80211_is_data(hdr->frame_control) && | |
290 | !ieee80211_is_auth(hdr->frame_control)) | |
9ae54c84 | 291 | return RX_CONTINUE; |
4f0d18e2 | 292 | |
eb9fb5b8 | 293 | if (!(status->flag & RX_FLAG_DECRYPTED)) { |
f4ea83dd | 294 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) |
e4c26add | 295 | return RX_DROP_UNUSABLE; |
eb9fb5b8 | 296 | } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
297 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
298 | /* remove ICV */ | |
d2984872 | 299 | skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN); |
4f0d18e2 JB |
300 | } |
301 | ||
9ae54c84 | 302 | return RX_CONTINUE; |
4f0d18e2 | 303 | } |
6a22a59d | 304 | |
5cf121c3 | 305 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 306 | { |
e039fa4a JB |
307 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
308 | ||
813d7669 | 309 | if (!info->control.hw_key) { |
c9cf0122 JB |
310 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, |
311 | tx->key->conf.keylen, | |
312 | tx->key->conf.keyidx)) | |
6a22a59d | 313 | return -1; |
e4fca007 JL |
314 | } else if (info->control.hw_key->flags & |
315 | IEEE80211_KEY_FLAG_GENERATE_IV) { | |
813d7669 JB |
316 | if (!ieee80211_wep_add_iv(tx->local, skb, |
317 | tx->key->conf.keylen, | |
318 | tx->key->conf.keyidx)) | |
319 | return -1; | |
320 | } | |
321 | ||
6a22a59d JB |
322 | return 0; |
323 | } | |
324 | ||
9ae54c84 | 325 | ieee80211_tx_result |
5cf121c3 | 326 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 327 | { |
2de8e0d9 | 328 | struct sk_buff *skb; |
c6a1fa12 | 329 | |
5cf121c3 | 330 | ieee80211_tx_set_protected(tx); |
6a22a59d | 331 | |
2de8e0d9 JB |
332 | skb = tx->skb; |
333 | do { | |
334 | if (wep_encrypt_skb(tx, skb) < 0) { | |
335 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
336 | return TX_DROP; | |
6a22a59d | 337 | } |
2de8e0d9 | 338 | } while ((skb = skb->next)); |
6a22a59d | 339 | |
9ae54c84 | 340 | return TX_CONTINUE; |
6a22a59d | 341 | } |