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/module.h>
13 #include <linux/init.h>
14 #include <linux/slab.h>
15 #include <linux/random.h>
16 #include <linux/skbuff.h>
17 #include <linux/netdevice.h>
18 #include <linux/if_ether.h>
19 #include <linux/if_arp.h>
20 #include <linux/string.h>
21 #include <linux/wireless.h>
22 #include "rtllib.h"
23
24 #include <linux/crypto.h>
25
26 #include <linux/scatterlist.h>
27
28 #define AES_BLOCK_LEN 16
29 #define CCMP_HDR_LEN 8
30 #define CCMP_MIC_LEN 8
31 #define CCMP_TK_LEN 16
32 #define CCMP_PN_LEN 6
33
34 struct rtllib_ccmp_data {
35 u8 key[CCMP_TK_LEN];
36 int key_set;
37
38 u8 tx_pn[CCMP_PN_LEN];
39 u8 rx_pn[CCMP_PN_LEN];
40
41 u32 dot11RSNAStatsCCMPFormatErrors;
42 u32 dot11RSNAStatsCCMPReplays;
43 u32 dot11RSNAStatsCCMPDecryptErrors;
44
45 int key_idx;
46
47 struct crypto_tfm *tfm;
48
49 /* scratch buffers for virt_to_page() (crypto API) */
50 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
51 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
52 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
53 };
54
rtllib_ccmp_aes_encrypt(struct crypto_tfm * tfm,const u8 pt[16],u8 ct[16])55 static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
56 const u8 pt[16], u8 ct[16])
57 {
58 crypto_cipher_encrypt_one((void *)tfm, ct, pt);
59 }
60
rtllib_ccmp_init(int key_idx)61 static void *rtllib_ccmp_init(int key_idx)
62 {
63 struct rtllib_ccmp_data *priv;
64
65 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
66 if (priv == NULL)
67 goto fail;
68 priv->key_idx = key_idx;
69
70 priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
71 if (IS_ERR(priv->tfm)) {
72 printk(KERN_DEBUG "rtllib_crypt_ccmp: could not allocate "
73 "crypto API aes\n");
74 priv->tfm = NULL;
75 goto fail;
76 }
77 return priv;
78
79 fail:
80 if (priv) {
81 if (priv->tfm)
82 crypto_free_cipher((void *)priv->tfm);
83 kfree(priv);
84 }
85
86 return NULL;
87 }
88
89
rtllib_ccmp_deinit(void * priv)90 static void rtllib_ccmp_deinit(void *priv)
91 {
92 struct rtllib_ccmp_data *_priv = priv;
93 if (_priv && _priv->tfm)
94 crypto_free_cipher((void *)_priv->tfm);
95 kfree(priv);
96 }
97
98
xor_block(u8 * b,u8 * a,size_t len)99 static inline void xor_block(u8 *b, u8 *a, size_t len)
100 {
101 int i;
102 for (i = 0; i < len; i++)
103 b[i] ^= a[i];
104 }
105
106
107
ccmp_init_blocks(struct crypto_tfm * tfm,struct rtllib_hdr_4addr * hdr,u8 * pn,size_t dlen,u8 * b0,u8 * auth,u8 * s0)108 static void ccmp_init_blocks(struct crypto_tfm *tfm,
109 struct rtllib_hdr_4addr *hdr,
110 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
111 u8 *s0)
112 {
113 u8 *pos, qc = 0;
114 size_t aad_len;
115 u16 fc;
116 int a4_included, qc_included;
117 u8 aad[2 * AES_BLOCK_LEN];
118
119 fc = le16_to_cpu(hdr->frame_ctl);
120 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
121 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
122 /*
123 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
124 (WLAN_FC_GET_STYPE(fc) & 0x08));
125 */
126 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
127 (WLAN_FC_GET_STYPE(fc) & 0x80));
128 aad_len = 22;
129 if (a4_included)
130 aad_len += 6;
131 if (qc_included) {
132 pos = (u8 *) &hdr->addr4;
133 if (a4_included)
134 pos += 6;
135 qc = *pos & 0x0f;
136 aad_len += 2;
137 }
138 /* CCM Initial Block:
139 * Flag (Include authentication header, M=3 (8-octet MIC),
140 * L=1 (2-octet Dlen))
141 * Nonce: 0x00 | A2 | PN
142 * Dlen */
143 b0[0] = 0x59;
144 b0[1] = qc;
145 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
146 memcpy(b0 + 8, pn, CCMP_PN_LEN);
147 b0[14] = (dlen >> 8) & 0xff;
148 b0[15] = dlen & 0xff;
149
150 /* AAD:
151 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
152 * A1 | A2 | A3
153 * SC with bits 4..15 (seq#) masked to zero
154 * A4 (if present)
155 * QC (if present)
156 */
157 pos = (u8 *) hdr;
158 aad[0] = 0; /* aad_len >> 8 */
159 aad[1] = aad_len & 0xff;
160 aad[2] = pos[0] & 0x8f;
161 aad[3] = pos[1] & 0xc7;
162 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
163 pos = (u8 *) &hdr->seq_ctl;
164 aad[22] = pos[0] & 0x0f;
165 aad[23] = 0; /* all bits masked */
166 memset(aad + 24, 0, 8);
167 if (a4_included)
168 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
169 if (qc_included) {
170 aad[a4_included ? 30 : 24] = qc;
171 /* rest of QC masked */
172 }
173
174 /* Start with the first block and AAD */
175 rtllib_ccmp_aes_encrypt(tfm, b0, auth);
176 xor_block(auth, aad, AES_BLOCK_LEN);
177 rtllib_ccmp_aes_encrypt(tfm, auth, auth);
178 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
179 rtllib_ccmp_aes_encrypt(tfm, auth, auth);
180 b0[0] &= 0x07;
181 b0[14] = b0[15] = 0;
182 rtllib_ccmp_aes_encrypt(tfm, b0, s0);
183 }
184
185
186
rtllib_ccmp_encrypt(struct sk_buff * skb,int hdr_len,void * priv)187 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
188 {
189 struct rtllib_ccmp_data *key = priv;
190 int data_len, i;
191 u8 *pos;
192 struct rtllib_hdr_4addr *hdr;
193 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
194 MAX_DEV_ADDR_SIZE);
195 if (skb_headroom(skb) < CCMP_HDR_LEN ||
196 skb_tailroom(skb) < CCMP_MIC_LEN ||
197 skb->len < hdr_len)
198 return -1;
199
200 data_len = skb->len - hdr_len;
201 pos = skb_push(skb, CCMP_HDR_LEN);
202 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
203 pos += hdr_len;
204
205 i = CCMP_PN_LEN - 1;
206 while (i >= 0) {
207 key->tx_pn[i]++;
208 if (key->tx_pn[i] != 0)
209 break;
210 i--;
211 }
212
213 *pos++ = key->tx_pn[5];
214 *pos++ = key->tx_pn[4];
215 *pos++ = 0;
216 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
217 *pos++ = key->tx_pn[3];
218 *pos++ = key->tx_pn[2];
219 *pos++ = key->tx_pn[1];
220 *pos++ = key->tx_pn[0];
221
222
223 hdr = (struct rtllib_hdr_4addr *) skb->data;
224 if (!tcb_desc->bHwSec) {
225 int blocks, last, len;
226 u8 *mic;
227 u8 *b0 = key->tx_b0;
228 u8 *b = key->tx_b;
229 u8 *e = key->tx_e;
230 u8 *s0 = key->tx_s0;
231
232 mic = skb_put(skb, CCMP_MIC_LEN);
233
234 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
235 b0, b, s0);
236
237 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
238 last = data_len % AES_BLOCK_LEN;
239
240 for (i = 1; i <= blocks; i++) {
241 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
242 /* Authentication */
243 xor_block(b, pos, len);
244 rtllib_ccmp_aes_encrypt(key->tfm, b, b);
245 /* Encryption, with counter */
246 b0[14] = (i >> 8) & 0xff;
247 b0[15] = i & 0xff;
248 rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
249 xor_block(pos, e, len);
250 pos += len;
251 }
252
253 for (i = 0; i < CCMP_MIC_LEN; i++)
254 mic[i] = b[i] ^ s0[i];
255 }
256 return 0;
257 }
258
259
rtllib_ccmp_decrypt(struct sk_buff * skb,int hdr_len,void * priv)260 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
261 {
262 struct rtllib_ccmp_data *key = priv;
263 u8 keyidx, *pos;
264 struct rtllib_hdr_4addr *hdr;
265 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
266 MAX_DEV_ADDR_SIZE);
267 u8 pn[6];
268
269 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
270 key->dot11RSNAStatsCCMPFormatErrors++;
271 return -1;
272 }
273
274 hdr = (struct rtllib_hdr_4addr *) skb->data;
275 pos = skb->data + hdr_len;
276 keyidx = pos[3];
277 if (!(keyidx & (1 << 5))) {
278 if (net_ratelimit()) {
279 printk(KERN_DEBUG "CCMP: received packet without ExtIV"
280 " flag from %pM\n", hdr->addr2);
281 }
282 key->dot11RSNAStatsCCMPFormatErrors++;
283 return -2;
284 }
285 keyidx >>= 6;
286 if (key->key_idx != keyidx) {
287 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
288 "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
289 return -6;
290 }
291 if (!key->key_set) {
292 if (net_ratelimit()) {
293 printk(KERN_DEBUG "CCMP: received packet from %pM"
294 " with keyid=%d that does not have a configured"
295 " key\n", hdr->addr2, keyidx);
296 }
297 return -3;
298 }
299
300 pn[0] = pos[7];
301 pn[1] = pos[6];
302 pn[2] = pos[5];
303 pn[3] = pos[4];
304 pn[4] = pos[1];
305 pn[5] = pos[0];
306 pos += 8;
307 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
308 key->dot11RSNAStatsCCMPReplays++;
309 return -4;
310 }
311 if (!tcb_desc->bHwSec) {
312 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
313 CCMP_MIC_LEN;
314 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
315 u8 *b0 = key->rx_b0;
316 u8 *b = key->rx_b;
317 u8 *a = key->rx_a;
318 int i, blocks, last, len;
319
320
321 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
322 xor_block(mic, b, CCMP_MIC_LEN);
323
324 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
325 last = data_len % AES_BLOCK_LEN;
326
327 for (i = 1; i <= blocks; i++) {
328 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
329 /* Decrypt, with counter */
330 b0[14] = (i >> 8) & 0xff;
331 b0[15] = i & 0xff;
332 rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
333 xor_block(pos, b, len);
334 /* Authentication */
335 xor_block(a, pos, len);
336 rtllib_ccmp_aes_encrypt(key->tfm, a, a);
337 pos += len;
338 }
339
340 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
341 if (net_ratelimit()) {
342 printk(KERN_DEBUG "CCMP: decrypt failed: STA="
343 " %pM\n", hdr->addr2);
344 }
345 key->dot11RSNAStatsCCMPDecryptErrors++;
346 return -5;
347 }
348
349 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
350 }
351 /* Remove hdr and MIC */
352 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
353 skb_pull(skb, CCMP_HDR_LEN);
354 skb_trim(skb, skb->len - CCMP_MIC_LEN);
355
356 return keyidx;
357 }
358
359
rtllib_ccmp_set_key(void * key,int len,u8 * seq,void * priv)360 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
361 {
362 struct rtllib_ccmp_data *data = priv;
363 int keyidx;
364 struct crypto_tfm *tfm = data->tfm;
365
366 keyidx = data->key_idx;
367 memset(data, 0, sizeof(*data));
368 data->key_idx = keyidx;
369 data->tfm = tfm;
370 if (len == CCMP_TK_LEN) {
371 memcpy(data->key, key, CCMP_TK_LEN);
372 data->key_set = 1;
373 if (seq) {
374 data->rx_pn[0] = seq[5];
375 data->rx_pn[1] = seq[4];
376 data->rx_pn[2] = seq[3];
377 data->rx_pn[3] = seq[2];
378 data->rx_pn[4] = seq[1];
379 data->rx_pn[5] = seq[0];
380 }
381 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
382 } else if (len == 0)
383 data->key_set = 0;
384 else
385 return -1;
386
387 return 0;
388 }
389
390
rtllib_ccmp_get_key(void * key,int len,u8 * seq,void * priv)391 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
392 {
393 struct rtllib_ccmp_data *data = priv;
394
395 if (len < CCMP_TK_LEN)
396 return -1;
397
398 if (!data->key_set)
399 return 0;
400 memcpy(key, data->key, CCMP_TK_LEN);
401
402 if (seq) {
403 seq[0] = data->tx_pn[5];
404 seq[1] = data->tx_pn[4];
405 seq[2] = data->tx_pn[3];
406 seq[3] = data->tx_pn[2];
407 seq[4] = data->tx_pn[1];
408 seq[5] = data->tx_pn[0];
409 }
410
411 return CCMP_TK_LEN;
412 }
413
414
rtllib_ccmp_print_stats(struct seq_file * m,void * priv)415 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
416 {
417 struct rtllib_ccmp_data *ccmp = priv;
418 seq_printf(m,
419 "key[%d] alg=CCMP key_set=%d "
420 "tx_pn=%pM rx_pn=%pM "
421 "format_errors=%d replays=%d decrypt_errors=%d\n",
422 ccmp->key_idx, ccmp->key_set,
423 ccmp->tx_pn, ccmp->rx_pn,
424 ccmp->dot11RSNAStatsCCMPFormatErrors,
425 ccmp->dot11RSNAStatsCCMPReplays,
426 ccmp->dot11RSNAStatsCCMPDecryptErrors);
427 }
428
429 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
430 .name = "R-CCMP",
431 .init = rtllib_ccmp_init,
432 .deinit = rtllib_ccmp_deinit,
433 .encrypt_mpdu = rtllib_ccmp_encrypt,
434 .decrypt_mpdu = rtllib_ccmp_decrypt,
435 .encrypt_msdu = NULL,
436 .decrypt_msdu = NULL,
437 .set_key = rtllib_ccmp_set_key,
438 .get_key = rtllib_ccmp_get_key,
439 .print_stats = rtllib_ccmp_print_stats,
440 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
441 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
442 .owner = THIS_MODULE,
443 };
444
445
rtllib_crypto_ccmp_init(void)446 int __init rtllib_crypto_ccmp_init(void)
447 {
448 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
449 }
450
451
rtllib_crypto_ccmp_exit(void)452 void __exit rtllib_crypto_ccmp_exit(void)
453 {
454 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
455 }
456
457 module_init(rtllib_crypto_ccmp_init);
458 module_exit(rtllib_crypto_ccmp_exit);
459
460 MODULE_LICENSE("GPL");
461