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b453872c JG |
1 | /* |
2 | * Host AP crypt: host-based CCMP encryption implementation for Host AP driver | |
3 | * | |
4 | * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi> | |
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. See README and COPYING for | |
9 | * more details. | |
10 | */ | |
11 | ||
12 | #include <linux/config.h> | |
13 | #include <linux/version.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/random.h> | |
18 | #include <linux/skbuff.h> | |
19 | #include <linux/netdevice.h> | |
20 | #include <linux/if_ether.h> | |
21 | #include <linux/if_arp.h> | |
22 | #include <asm/string.h> | |
23 | #include <linux/wireless.h> | |
24 | ||
25 | #include <net/ieee80211.h> | |
26 | ||
27 | ||
28 | #include <linux/crypto.h> | |
29 | #include <asm/scatterlist.h> | |
30 | ||
31 | MODULE_AUTHOR("Jouni Malinen"); | |
32 | MODULE_DESCRIPTION("Host AP crypt: CCMP"); | |
33 | MODULE_LICENSE("GPL"); | |
34 | ||
35 | #define AES_BLOCK_LEN 16 | |
36 | #define CCMP_HDR_LEN 8 | |
37 | #define CCMP_MIC_LEN 8 | |
38 | #define CCMP_TK_LEN 16 | |
39 | #define CCMP_PN_LEN 6 | |
40 | ||
41 | struct ieee80211_ccmp_data { | |
42 | u8 key[CCMP_TK_LEN]; | |
43 | int key_set; | |
44 | ||
45 | u8 tx_pn[CCMP_PN_LEN]; | |
46 | u8 rx_pn[CCMP_PN_LEN]; | |
47 | ||
48 | u32 dot11RSNAStatsCCMPFormatErrors; | |
49 | u32 dot11RSNAStatsCCMPReplays; | |
50 | u32 dot11RSNAStatsCCMPDecryptErrors; | |
51 | ||
52 | int key_idx; | |
53 | ||
54 | struct crypto_tfm *tfm; | |
55 | ||
56 | /* scratch buffers for virt_to_page() (crypto API) */ | |
57 | u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN], | |
58 | tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN]; | |
59 | u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN]; | |
60 | }; | |
61 | ||
e157249d AB |
62 | static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm, |
63 | const u8 pt[16], u8 ct[16]) | |
b453872c JG |
64 | { |
65 | struct scatterlist src, dst; | |
66 | ||
67 | src.page = virt_to_page(pt); | |
68 | src.offset = offset_in_page(pt); | |
69 | src.length = AES_BLOCK_LEN; | |
70 | ||
71 | dst.page = virt_to_page(ct); | |
72 | dst.offset = offset_in_page(ct); | |
73 | dst.length = AES_BLOCK_LEN; | |
74 | ||
75 | crypto_cipher_encrypt(tfm, &dst, &src, AES_BLOCK_LEN); | |
76 | } | |
77 | ||
78 | static void * ieee80211_ccmp_init(int key_idx) | |
79 | { | |
80 | struct ieee80211_ccmp_data *priv; | |
81 | ||
82 | priv = kmalloc(sizeof(*priv), GFP_ATOMIC); | |
83 | if (priv == NULL) | |
84 | goto fail; | |
85 | memset(priv, 0, sizeof(*priv)); | |
86 | priv->key_idx = key_idx; | |
87 | ||
88 | priv->tfm = crypto_alloc_tfm("aes", 0); | |
89 | if (priv->tfm == NULL) { | |
90 | printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate " | |
91 | "crypto API aes\n"); | |
92 | goto fail; | |
93 | } | |
94 | ||
95 | return priv; | |
96 | ||
97 | fail: | |
98 | if (priv) { | |
99 | if (priv->tfm) | |
100 | crypto_free_tfm(priv->tfm); | |
101 | kfree(priv); | |
102 | } | |
103 | ||
104 | return NULL; | |
105 | } | |
106 | ||
107 | ||
108 | static void ieee80211_ccmp_deinit(void *priv) | |
109 | { | |
110 | struct ieee80211_ccmp_data *_priv = priv; | |
111 | if (_priv && _priv->tfm) | |
112 | crypto_free_tfm(_priv->tfm); | |
113 | kfree(priv); | |
114 | } | |
115 | ||
116 | ||
117 | static inline void xor_block(u8 *b, u8 *a, size_t len) | |
118 | { | |
119 | int i; | |
120 | for (i = 0; i < len; i++) | |
121 | b[i] ^= a[i]; | |
122 | } | |
123 | ||
124 | ||
125 | static void ccmp_init_blocks(struct crypto_tfm *tfm, | |
126 | struct ieee80211_hdr *hdr, | |
127 | u8 *pn, size_t dlen, u8 *b0, u8 *auth, | |
128 | u8 *s0) | |
129 | { | |
130 | u8 *pos, qc = 0; | |
131 | size_t aad_len; | |
132 | u16 fc; | |
133 | int a4_included, qc_included; | |
134 | u8 aad[2 * AES_BLOCK_LEN]; | |
135 | ||
136 | fc = le16_to_cpu(hdr->frame_ctl); | |
137 | a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) == | |
138 | (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)); | |
139 | qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) && | |
140 | (WLAN_FC_GET_STYPE(fc) & 0x08)); | |
141 | aad_len = 22; | |
142 | if (a4_included) | |
143 | aad_len += 6; | |
144 | if (qc_included) { | |
145 | pos = (u8 *) &hdr->addr4; | |
146 | if (a4_included) | |
147 | pos += 6; | |
148 | qc = *pos & 0x0f; | |
149 | aad_len += 2; | |
150 | } | |
151 | ||
152 | /* CCM Initial Block: | |
153 | * Flag (Include authentication header, M=3 (8-octet MIC), | |
154 | * L=1 (2-octet Dlen)) | |
155 | * Nonce: 0x00 | A2 | PN | |
156 | * Dlen */ | |
157 | b0[0] = 0x59; | |
158 | b0[1] = qc; | |
159 | memcpy(b0 + 2, hdr->addr2, ETH_ALEN); | |
160 | memcpy(b0 + 8, pn, CCMP_PN_LEN); | |
161 | b0[14] = (dlen >> 8) & 0xff; | |
162 | b0[15] = dlen & 0xff; | |
163 | ||
164 | /* AAD: | |
165 | * FC with bits 4..6 and 11..13 masked to zero; 14 is always one | |
166 | * A1 | A2 | A3 | |
167 | * SC with bits 4..15 (seq#) masked to zero | |
168 | * A4 (if present) | |
169 | * QC (if present) | |
170 | */ | |
171 | pos = (u8 *) hdr; | |
172 | aad[0] = 0; /* aad_len >> 8 */ | |
173 | aad[1] = aad_len & 0xff; | |
174 | aad[2] = pos[0] & 0x8f; | |
175 | aad[3] = pos[1] & 0xc7; | |
176 | memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN); | |
177 | pos = (u8 *) &hdr->seq_ctl; | |
178 | aad[22] = pos[0] & 0x0f; | |
179 | aad[23] = 0; /* all bits masked */ | |
180 | memset(aad + 24, 0, 8); | |
181 | if (a4_included) | |
182 | memcpy(aad + 24, hdr->addr4, ETH_ALEN); | |
183 | if (qc_included) { | |
184 | aad[a4_included ? 30 : 24] = qc; | |
185 | /* rest of QC masked */ | |
186 | } | |
187 | ||
188 | /* Start with the first block and AAD */ | |
189 | ieee80211_ccmp_aes_encrypt(tfm, b0, auth); | |
190 | xor_block(auth, aad, AES_BLOCK_LEN); | |
191 | ieee80211_ccmp_aes_encrypt(tfm, auth, auth); | |
192 | xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN); | |
193 | ieee80211_ccmp_aes_encrypt(tfm, auth, auth); | |
194 | b0[0] &= 0x07; | |
195 | b0[14] = b0[15] = 0; | |
196 | ieee80211_ccmp_aes_encrypt(tfm, b0, s0); | |
197 | } | |
198 | ||
199 | ||
200 | static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) | |
201 | { | |
202 | struct ieee80211_ccmp_data *key = priv; | |
203 | int data_len, i, blocks, last, len; | |
204 | u8 *pos, *mic; | |
205 | struct ieee80211_hdr *hdr; | |
206 | u8 *b0 = key->tx_b0; | |
207 | u8 *b = key->tx_b; | |
208 | u8 *e = key->tx_e; | |
209 | u8 *s0 = key->tx_s0; | |
210 | ||
211 | if (skb_headroom(skb) < CCMP_HDR_LEN || | |
212 | skb_tailroom(skb) < CCMP_MIC_LEN || | |
213 | skb->len < hdr_len) | |
214 | return -1; | |
215 | ||
216 | data_len = skb->len - hdr_len; | |
217 | pos = skb_push(skb, CCMP_HDR_LEN); | |
218 | memmove(pos, pos + CCMP_HDR_LEN, hdr_len); | |
219 | pos += hdr_len; | |
220 | mic = skb_put(skb, CCMP_MIC_LEN); | |
221 | ||
222 | i = CCMP_PN_LEN - 1; | |
223 | while (i >= 0) { | |
224 | key->tx_pn[i]++; | |
225 | if (key->tx_pn[i] != 0) | |
226 | break; | |
227 | i--; | |
228 | } | |
229 | ||
230 | *pos++ = key->tx_pn[5]; | |
231 | *pos++ = key->tx_pn[4]; | |
232 | *pos++ = 0; | |
233 | *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */; | |
234 | *pos++ = key->tx_pn[3]; | |
235 | *pos++ = key->tx_pn[2]; | |
236 | *pos++ = key->tx_pn[1]; | |
237 | *pos++ = key->tx_pn[0]; | |
238 | ||
239 | hdr = (struct ieee80211_hdr *) skb->data; | |
240 | ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0); | |
241 | ||
242 | blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; | |
243 | last = data_len % AES_BLOCK_LEN; | |
244 | ||
245 | for (i = 1; i <= blocks; i++) { | |
246 | len = (i == blocks && last) ? last : AES_BLOCK_LEN; | |
247 | /* Authentication */ | |
248 | xor_block(b, pos, len); | |
249 | ieee80211_ccmp_aes_encrypt(key->tfm, b, b); | |
250 | /* Encryption, with counter */ | |
251 | b0[14] = (i >> 8) & 0xff; | |
252 | b0[15] = i & 0xff; | |
253 | ieee80211_ccmp_aes_encrypt(key->tfm, b0, e); | |
254 | xor_block(pos, e, len); | |
255 | pos += len; | |
256 | } | |
257 | ||
258 | for (i = 0; i < CCMP_MIC_LEN; i++) | |
259 | mic[i] = b[i] ^ s0[i]; | |
260 | ||
261 | return 0; | |
262 | } | |
263 | ||
264 | ||
265 | static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) | |
266 | { | |
267 | struct ieee80211_ccmp_data *key = priv; | |
268 | u8 keyidx, *pos; | |
269 | struct ieee80211_hdr *hdr; | |
270 | u8 *b0 = key->rx_b0; | |
271 | u8 *b = key->rx_b; | |
272 | u8 *a = key->rx_a; | |
273 | u8 pn[6]; | |
274 | int i, blocks, last, len; | |
275 | size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN; | |
276 | u8 *mic = skb->data + skb->len - CCMP_MIC_LEN; | |
277 | ||
278 | if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { | |
279 | key->dot11RSNAStatsCCMPFormatErrors++; | |
280 | return -1; | |
281 | } | |
282 | ||
283 | hdr = (struct ieee80211_hdr *) skb->data; | |
284 | pos = skb->data + hdr_len; | |
285 | keyidx = pos[3]; | |
286 | if (!(keyidx & (1 << 5))) { | |
287 | if (net_ratelimit()) { | |
288 | printk(KERN_DEBUG "CCMP: received packet without ExtIV" | |
289 | " flag from " MAC_FMT "\n", MAC_ARG(hdr->addr2)); | |
290 | } | |
291 | key->dot11RSNAStatsCCMPFormatErrors++; | |
292 | return -2; | |
293 | } | |
294 | keyidx >>= 6; | |
295 | if (key->key_idx != keyidx) { | |
296 | printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame " | |
297 | "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv); | |
298 | return -6; | |
299 | } | |
300 | if (!key->key_set) { | |
301 | if (net_ratelimit()) { | |
302 | printk(KERN_DEBUG "CCMP: received packet from " MAC_FMT | |
303 | " with keyid=%d that does not have a configured" | |
304 | " key\n", MAC_ARG(hdr->addr2), keyidx); | |
305 | } | |
306 | return -3; | |
307 | } | |
308 | ||
309 | pn[0] = pos[7]; | |
310 | pn[1] = pos[6]; | |
311 | pn[2] = pos[5]; | |
312 | pn[3] = pos[4]; | |
313 | pn[4] = pos[1]; | |
314 | pn[5] = pos[0]; | |
315 | pos += 8; | |
316 | ||
317 | if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) { | |
318 | if (net_ratelimit()) { | |
319 | printk(KERN_DEBUG "CCMP: replay detected: STA=" MAC_FMT | |
320 | " previous PN %02x%02x%02x%02x%02x%02x " | |
321 | "received PN %02x%02x%02x%02x%02x%02x\n", | |
322 | MAC_ARG(hdr->addr2), MAC_ARG(key->rx_pn), | |
323 | MAC_ARG(pn)); | |
324 | } | |
325 | key->dot11RSNAStatsCCMPReplays++; | |
326 | return -4; | |
327 | } | |
328 | ||
329 | ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b); | |
330 | xor_block(mic, b, CCMP_MIC_LEN); | |
331 | ||
332 | blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; | |
333 | last = data_len % AES_BLOCK_LEN; | |
334 | ||
335 | for (i = 1; i <= blocks; i++) { | |
336 | len = (i == blocks && last) ? last : AES_BLOCK_LEN; | |
337 | /* Decrypt, with counter */ | |
338 | b0[14] = (i >> 8) & 0xff; | |
339 | b0[15] = i & 0xff; | |
340 | ieee80211_ccmp_aes_encrypt(key->tfm, b0, b); | |
341 | xor_block(pos, b, len); | |
342 | /* Authentication */ | |
343 | xor_block(a, pos, len); | |
344 | ieee80211_ccmp_aes_encrypt(key->tfm, a, a); | |
345 | pos += len; | |
346 | } | |
347 | ||
348 | if (memcmp(mic, a, CCMP_MIC_LEN) != 0) { | |
349 | if (net_ratelimit()) { | |
350 | printk(KERN_DEBUG "CCMP: decrypt failed: STA=" | |
351 | MAC_FMT "\n", MAC_ARG(hdr->addr2)); | |
352 | } | |
353 | key->dot11RSNAStatsCCMPDecryptErrors++; | |
354 | return -5; | |
355 | } | |
356 | ||
357 | memcpy(key->rx_pn, pn, CCMP_PN_LEN); | |
358 | ||
359 | /* Remove hdr and MIC */ | |
360 | memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); | |
361 | skb_pull(skb, CCMP_HDR_LEN); | |
362 | skb_trim(skb, skb->len - CCMP_MIC_LEN); | |
363 | ||
364 | return keyidx; | |
365 | } | |
366 | ||
367 | ||
368 | static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv) | |
369 | { | |
370 | struct ieee80211_ccmp_data *data = priv; | |
371 | int keyidx; | |
372 | struct crypto_tfm *tfm = data->tfm; | |
373 | ||
374 | keyidx = data->key_idx; | |
375 | memset(data, 0, sizeof(*data)); | |
376 | data->key_idx = keyidx; | |
377 | data->tfm = tfm; | |
378 | if (len == CCMP_TK_LEN) { | |
379 | memcpy(data->key, key, CCMP_TK_LEN); | |
380 | data->key_set = 1; | |
381 | if (seq) { | |
382 | data->rx_pn[0] = seq[5]; | |
383 | data->rx_pn[1] = seq[4]; | |
384 | data->rx_pn[2] = seq[3]; | |
385 | data->rx_pn[3] = seq[2]; | |
386 | data->rx_pn[4] = seq[1]; | |
387 | data->rx_pn[5] = seq[0]; | |
388 | } | |
389 | crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN); | |
390 | } else if (len == 0) | |
391 | data->key_set = 0; | |
392 | else | |
393 | return -1; | |
394 | ||
395 | return 0; | |
396 | } | |
397 | ||
398 | ||
399 | static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv) | |
400 | { | |
401 | struct ieee80211_ccmp_data *data = priv; | |
402 | ||
403 | if (len < CCMP_TK_LEN) | |
404 | return -1; | |
405 | ||
406 | if (!data->key_set) | |
407 | return 0; | |
408 | memcpy(key, data->key, CCMP_TK_LEN); | |
409 | ||
410 | if (seq) { | |
411 | seq[0] = data->tx_pn[5]; | |
412 | seq[1] = data->tx_pn[4]; | |
413 | seq[2] = data->tx_pn[3]; | |
414 | seq[3] = data->tx_pn[2]; | |
415 | seq[4] = data->tx_pn[1]; | |
416 | seq[5] = data->tx_pn[0]; | |
417 | } | |
418 | ||
419 | return CCMP_TK_LEN; | |
420 | } | |
421 | ||
422 | ||
423 | static char * ieee80211_ccmp_print_stats(char *p, void *priv) | |
424 | { | |
425 | struct ieee80211_ccmp_data *ccmp = priv; | |
426 | p += sprintf(p, "key[%d] alg=CCMP key_set=%d " | |
427 | "tx_pn=%02x%02x%02x%02x%02x%02x " | |
428 | "rx_pn=%02x%02x%02x%02x%02x%02x " | |
429 | "format_errors=%d replays=%d decrypt_errors=%d\n", | |
430 | ccmp->key_idx, ccmp->key_set, | |
431 | MAC_ARG(ccmp->tx_pn), MAC_ARG(ccmp->rx_pn), | |
432 | ccmp->dot11RSNAStatsCCMPFormatErrors, | |
433 | ccmp->dot11RSNAStatsCCMPReplays, | |
434 | ccmp->dot11RSNAStatsCCMPDecryptErrors); | |
435 | ||
436 | return p; | |
437 | } | |
438 | ||
439 | ||
440 | static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = { | |
441 | .name = "CCMP", | |
442 | .init = ieee80211_ccmp_init, | |
443 | .deinit = ieee80211_ccmp_deinit, | |
444 | .encrypt_mpdu = ieee80211_ccmp_encrypt, | |
445 | .decrypt_mpdu = ieee80211_ccmp_decrypt, | |
446 | .encrypt_msdu = NULL, | |
447 | .decrypt_msdu = NULL, | |
448 | .set_key = ieee80211_ccmp_set_key, | |
449 | .get_key = ieee80211_ccmp_get_key, | |
450 | .print_stats = ieee80211_ccmp_print_stats, | |
451 | .extra_prefix_len = CCMP_HDR_LEN, | |
452 | .extra_postfix_len = CCMP_MIC_LEN, | |
453 | .owner = THIS_MODULE, | |
454 | }; | |
455 | ||
456 | ||
457 | static int __init ieee80211_crypto_ccmp_init(void) | |
458 | { | |
459 | return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp); | |
460 | } | |
461 | ||
462 | ||
463 | static void __exit ieee80211_crypto_ccmp_exit(void) | |
464 | { | |
465 | ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp); | |
466 | } | |
467 | ||
468 | ||
469 | module_init(ieee80211_crypto_ccmp_init); | |
470 | module_exit(ieee80211_crypto_ccmp_exit); |