Commit | Line | Data |
---|---|---|
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); | |
088c8726 JL |
35 | if (IS_ERR(local->wep_tx_tfm)) { |
36 | local->wep_rx_tfm = ERR_PTR(-EINVAL); | |
023a04be | 37 | return PTR_ERR(local->wep_tx_tfm); |
088c8726 | 38 | } |
f0706e82 JB |
39 | |
40 | local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, | |
41 | CRYPTO_ALG_ASYNC); | |
42 | if (IS_ERR(local->wep_rx_tfm)) { | |
43 | crypto_free_blkcipher(local->wep_tx_tfm); | |
088c8726 | 44 | local->wep_tx_tfm = ERR_PTR(-EINVAL); |
023a04be | 45 | return PTR_ERR(local->wep_rx_tfm); |
f0706e82 JB |
46 | } |
47 | ||
48 | return 0; | |
49 | } | |
50 | ||
51 | void ieee80211_wep_free(struct ieee80211_local *local) | |
52 | { | |
3473187d JL |
53 | if (!IS_ERR(local->wep_tx_tfm)) |
54 | crypto_free_blkcipher(local->wep_tx_tfm); | |
55 | if (!IS_ERR(local->wep_rx_tfm)) | |
56 | crypto_free_blkcipher(local->wep_rx_tfm); | |
f0706e82 JB |
57 | } |
58 | ||
c6a1fa12 | 59 | static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) |
f0706e82 | 60 | { |
c6a1fa12 JB |
61 | /* |
62 | * Fluhrer, Mantin, and Shamir have reported weaknesses in the | |
f0706e82 | 63 | * key scheduling algorithm of RC4. At least IVs (KeyByte + 3, |
c6a1fa12 JB |
64 | * 0xff, N) can be used to speedup attacks, so avoid using them. |
65 | */ | |
f0706e82 JB |
66 | if ((iv & 0xff00) == 0xff00) { |
67 | u8 B = (iv >> 16) & 0xff; | |
68 | if (B >= 3 && B < 3 + keylen) | |
c6a1fa12 | 69 | return true; |
f0706e82 | 70 | } |
c6a1fa12 | 71 | return false; |
f0706e82 JB |
72 | } |
73 | ||
74 | ||
4f0d18e2 | 75 | static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
c9cf0122 | 76 | int keylen, int keyidx, u8 *iv) |
f0706e82 JB |
77 | { |
78 | local->wep_iv++; | |
c9cf0122 | 79 | if (ieee80211_wep_weak_iv(local->wep_iv, keylen)) |
f0706e82 JB |
80 | local->wep_iv += 0x0100; |
81 | ||
82 | if (!iv) | |
83 | return; | |
84 | ||
85 | *iv++ = (local->wep_iv >> 16) & 0xff; | |
86 | *iv++ = (local->wep_iv >> 8) & 0xff; | |
87 | *iv++ = local->wep_iv & 0xff; | |
c9cf0122 | 88 | *iv++ = keyidx << 6; |
f0706e82 JB |
89 | } |
90 | ||
91 | ||
6a22a59d JB |
92 | static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, |
93 | struct sk_buff *skb, | |
c9cf0122 | 94 | int keylen, int keyidx) |
f0706e82 | 95 | { |
70217d7f HH |
96 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
97 | unsigned int hdrlen; | |
f0706e82 JB |
98 | u8 *newhdr; |
99 | ||
70217d7f | 100 | hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
f0706e82 | 101 | |
23c0752a JB |
102 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
103 | skb_headroom(skb) < WEP_IV_LEN)) | |
104 | return NULL; | |
f0706e82 | 105 | |
70217d7f | 106 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
107 | newhdr = skb_push(skb, WEP_IV_LEN); |
108 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
c9cf0122 | 109 | ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen); |
f0706e82 JB |
110 | return newhdr + hdrlen; |
111 | } | |
112 | ||
113 | ||
4f0d18e2 JB |
114 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
115 | struct sk_buff *skb, | |
116 | struct ieee80211_key *key) | |
f0706e82 | 117 | { |
70217d7f HH |
118 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
119 | unsigned int hdrlen; | |
f0706e82 | 120 | |
70217d7f | 121 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
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)) */ | |
3473187d JL |
130 | int ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, |
131 | size_t klen, u8 *data, size_t data_len) | |
f0706e82 JB |
132 | { |
133 | struct blkcipher_desc desc = { .tfm = tfm }; | |
134 | struct scatterlist sg; | |
860c6e6a | 135 | __le32 icv; |
f0706e82 | 136 | |
3473187d JL |
137 | if (IS_ERR(tfm)) |
138 | return -1; | |
139 | ||
860c6e6a IK |
140 | icv = cpu_to_le32(~crc32_le(~0, data, data_len)); |
141 | put_unaligned(icv, (__le32 *)(data + data_len)); | |
f0706e82 JB |
142 | |
143 | crypto_blkcipher_setkey(tfm, rc4key, klen); | |
fa05f128 | 144 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 | 145 | crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); |
3473187d JL |
146 | |
147 | return 0; | |
f0706e82 JB |
148 | } |
149 | ||
150 | ||
151 | /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the | |
152 | * beginning of the buffer 4 bytes of extra space (ICV) in the end of the | |
153 | * buffer will be added. Both IV and ICV will be transmitted, so the | |
154 | * payload length increases with 8 bytes. | |
155 | * | |
156 | * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) | |
157 | */ | |
fffd0934 JB |
158 | int ieee80211_wep_encrypt(struct ieee80211_local *local, |
159 | struct sk_buff *skb, | |
160 | const u8 *key, int keylen, int keyidx) | |
f0706e82 | 161 | { |
c9cf0122 | 162 | u8 *iv; |
f0706e82 | 163 | size_t len; |
c9cf0122 | 164 | u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
f0706e82 | 165 | |
c9cf0122 JB |
166 | iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); |
167 | if (!iv) | |
f0706e82 | 168 | return -1; |
f0706e82 JB |
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) */ | |
c9cf0122 | 176 | memcpy(rc4key + 3, key, keylen); |
f0706e82 JB |
177 | |
178 | /* Add room for ICV */ | |
179 | skb_put(skb, WEP_ICV_LEN); | |
180 | ||
3473187d JL |
181 | return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3, |
182 | iv + WEP_IV_LEN, len); | |
f0706e82 JB |
183 | } |
184 | ||
185 | ||
186 | /* Perform WEP decryption using given key. data buffer includes encrypted | |
187 | * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. | |
188 | * Return 0 on success and -1 on ICV mismatch. */ | |
189 | int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, | |
190 | size_t klen, u8 *data, size_t data_len) | |
191 | { | |
192 | struct blkcipher_desc desc = { .tfm = tfm }; | |
193 | struct scatterlist sg; | |
194 | __le32 crc; | |
195 | ||
3473187d JL |
196 | if (IS_ERR(tfm)) |
197 | return -1; | |
198 | ||
f0706e82 | 199 | crypto_blkcipher_setkey(tfm, rc4key, klen); |
fa05f128 | 200 | sg_init_one(&sg, data, data_len + WEP_ICV_LEN); |
f0706e82 JB |
201 | crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); |
202 | ||
203 | crc = cpu_to_le32(~crc32_le(~0, data, data_len)); | |
204 | if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0) | |
205 | /* ICV mismatch */ | |
206 | return -1; | |
207 | ||
208 | return 0; | |
209 | } | |
210 | ||
211 | ||
212 | /* Perform WEP decryption on given skb. Buffer includes whole WEP part of | |
213 | * the frame: IV (4 bytes), encrypted payload (including SNAP header), | |
214 | * ICV (4 bytes). skb->len includes both IV and ICV. | |
215 | * | |
216 | * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on | |
217 | * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload | |
218 | * is moved to the beginning of the skb and skb length will be reduced. | |
219 | */ | |
c9cf0122 JB |
220 | static int ieee80211_wep_decrypt(struct ieee80211_local *local, |
221 | struct sk_buff *skb, | |
222 | struct ieee80211_key *key) | |
f0706e82 JB |
223 | { |
224 | u32 klen; | |
730bd83b | 225 | u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
f0706e82 | 226 | u8 keyidx; |
70217d7f HH |
227 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
228 | unsigned int hdrlen; | |
f0706e82 JB |
229 | size_t len; |
230 | int ret = 0; | |
231 | ||
70217d7f | 232 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
233 | return -1; |
234 | ||
70217d7f | 235 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
d2984872 | 236 | if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
f0706e82 JB |
237 | return -1; |
238 | ||
d2984872 | 239 | len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
f0706e82 JB |
240 | |
241 | keyidx = skb->data[hdrlen + 3] >> 6; | |
242 | ||
97359d12 | 243 | if (!key || keyidx != key->conf.keyidx) |
f0706e82 JB |
244 | return -1; |
245 | ||
8f20fc24 | 246 | klen = 3 + key->conf.keylen; |
f0706e82 | 247 | |
f0706e82 JB |
248 | /* Prepend 24-bit IV to RC4 key */ |
249 | memcpy(rc4key, skb->data + hdrlen, 3); | |
250 | ||
251 | /* Copy rest of the WEP key (the secret part) */ | |
8f20fc24 | 252 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
253 | |
254 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
255 | skb->data + hdrlen + WEP_IV_LEN, | |
f4ea83dd | 256 | len)) |
f0706e82 | 257 | ret = -1; |
f0706e82 | 258 | |
f0706e82 JB |
259 | /* Trim ICV */ |
260 | skb_trim(skb, skb->len - WEP_ICV_LEN); | |
261 | ||
262 | /* Remove IV */ | |
263 | memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); | |
264 | skb_pull(skb, WEP_IV_LEN); | |
265 | ||
266 | return ret; | |
267 | } | |
268 | ||
269 | ||
c6a1fa12 | 270 | bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
f0706e82 | 271 | { |
70217d7f HH |
272 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
273 | unsigned int hdrlen; | |
f0706e82 JB |
274 | u8 *ivpos; |
275 | u32 iv; | |
276 | ||
70217d7f | 277 | if (!ieee80211_has_protected(hdr->frame_control)) |
c6a1fa12 | 278 | return false; |
f0706e82 | 279 | |
70217d7f | 280 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
281 | ivpos = skb->data + hdrlen; |
282 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
283 | ||
c6a1fa12 | 284 | return ieee80211_wep_weak_iv(iv, key->conf.keylen); |
f0706e82 | 285 | } |
4f0d18e2 | 286 | |
9ae54c84 | 287 | ieee80211_rx_result |
5cf121c3 | 288 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 | 289 | { |
eb9fb5b8 JB |
290 | struct sk_buff *skb = rx->skb; |
291 | struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); | |
292 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; | |
358c8d9d HH |
293 | |
294 | if (!ieee80211_is_data(hdr->frame_control) && | |
295 | !ieee80211_is_auth(hdr->frame_control)) | |
9ae54c84 | 296 | return RX_CONTINUE; |
4f0d18e2 | 297 | |
eb9fb5b8 | 298 | if (!(status->flag & RX_FLAG_DECRYPTED)) { |
f4ea83dd | 299 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) |
e4c26add | 300 | return RX_DROP_UNUSABLE; |
eb9fb5b8 | 301 | } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
302 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
303 | /* remove ICV */ | |
d2984872 | 304 | skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN); |
4f0d18e2 JB |
305 | } |
306 | ||
9ae54c84 | 307 | return RX_CONTINUE; |
4f0d18e2 | 308 | } |
6a22a59d | 309 | |
5cf121c3 | 310 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 311 | { |
e039fa4a JB |
312 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
313 | ||
813d7669 | 314 | if (!info->control.hw_key) { |
c9cf0122 JB |
315 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, |
316 | tx->key->conf.keylen, | |
317 | tx->key->conf.keyidx)) | |
6a22a59d | 318 | return -1; |
e4fca007 JL |
319 | } else if (info->control.hw_key->flags & |
320 | IEEE80211_KEY_FLAG_GENERATE_IV) { | |
813d7669 JB |
321 | if (!ieee80211_wep_add_iv(tx->local, skb, |
322 | tx->key->conf.keylen, | |
323 | tx->key->conf.keyidx)) | |
324 | return -1; | |
325 | } | |
326 | ||
6a22a59d JB |
327 | return 0; |
328 | } | |
329 | ||
9ae54c84 | 330 | ieee80211_tx_result |
5cf121c3 | 331 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 332 | { |
2de8e0d9 | 333 | struct sk_buff *skb; |
c6a1fa12 | 334 | |
5cf121c3 | 335 | ieee80211_tx_set_protected(tx); |
6a22a59d | 336 | |
2de8e0d9 JB |
337 | skb = tx->skb; |
338 | do { | |
339 | if (wep_encrypt_skb(tx, skb) < 0) { | |
340 | I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); | |
341 | return TX_DROP; | |
6a22a59d | 342 | } |
2de8e0d9 | 343 | } while ((skb = skb->next)); |
6a22a59d | 344 | |
9ae54c84 | 345 | return TX_CONTINUE; |
6a22a59d | 346 | } |