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
23 #include "ieee80211.h"
24
25 #include <linux/crypto.h>
26 #include <linux/scatterlist.h>
27
28 MODULE_AUTHOR("Jouni Malinen");
29 MODULE_DESCRIPTION("Host AP crypt: CCMP");
30 MODULE_LICENSE("GPL");
31
32 #define AES_BLOCK_LEN 16
33 #define CCMP_HDR_LEN 8
34 #define CCMP_MIC_LEN 8
35 #define CCMP_TK_LEN 16
36 #define CCMP_PN_LEN 6
37
38 struct ieee80211_ccmp_data {
39 u8 key[CCMP_TK_LEN];
40 int key_set;
41
42 u8 tx_pn[CCMP_PN_LEN];
43 u8 rx_pn[CCMP_PN_LEN];
44
45 u32 dot11RSNAStatsCCMPFormatErrors;
46 u32 dot11RSNAStatsCCMPReplays;
47 u32 dot11RSNAStatsCCMPDecryptErrors;
48
49 int key_idx;
50
51 struct crypto_tfm *tfm;
52
53 /* scratch buffers for virt_to_page() (crypto API) */
54 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
55 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
56 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
57 };
58
ieee80211_ccmp_aes_encrypt(struct crypto_tfm * tfm,const u8 pt[16],u8 ct[16])59 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
60 const u8 pt[16], u8 ct[16])
61 {
62 crypto_cipher_encrypt_one((void *)tfm, ct, pt);
63 }
64
ieee80211_ccmp_init(int key_idx)65 static void *ieee80211_ccmp_init(int key_idx)
66 {
67 struct ieee80211_ccmp_data *priv;
68
69 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
70 if (!priv)
71 goto fail;
72 priv->key_idx = key_idx;
73
74 priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
75 if (IS_ERR(priv->tfm)) {
76 pr_debug("ieee80211_crypt_ccmp: could not allocate crypto API aes\n");
77 priv->tfm = NULL;
78 goto fail;
79 }
80
81 return priv;
82
83 fail:
84 if (priv) {
85 if (priv->tfm)
86 crypto_free_cipher((void *)priv->tfm);
87 kfree(priv);
88 }
89
90 return NULL;
91 }
92
ieee80211_ccmp_deinit(void * priv)93 static void ieee80211_ccmp_deinit(void *priv)
94 {
95 struct ieee80211_ccmp_data *_priv = priv;
96
97 if (_priv && _priv->tfm)
98 crypto_free_cipher((void *)_priv->tfm);
99 kfree(priv);
100 }
101
xor_block(u8 * b,u8 * a,size_t len)102 static inline void xor_block(u8 *b, u8 *a, size_t len)
103 {
104 int i;
105
106 for (i = 0; i < len; i++)
107 b[i] ^= a[i];
108 }
109
ccmp_init_blocks(struct crypto_tfm * tfm,struct rtl_80211_hdr_4addr * hdr,u8 * pn,size_t dlen,u8 * b0,u8 * auth,u8 * s0)110 static void ccmp_init_blocks(struct crypto_tfm *tfm,
111 struct rtl_80211_hdr_4addr *hdr,
112 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
113 u8 *s0)
114 {
115 u8 *pos, qc = 0;
116 size_t aad_len;
117 u16 fc;
118 int a4_included, qc_included;
119 u8 aad[2 * AES_BLOCK_LEN];
120
121 fc = le16_to_cpu(hdr->frame_ctl);
122 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
123 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
124 /* qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
125 * (WLAN_FC_GET_STYPE(fc) & 0x08));
126 */
127 /* fixed by David :2006.9.6 */
128 qc_included = (WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
129 (WLAN_FC_GET_STYPE(fc) & 0x80);
130 aad_len = 22;
131 if (a4_included)
132 aad_len += 6;
133 if (qc_included) {
134 pos = (u8 *)&hdr->addr4;
135 if (a4_included)
136 pos += 6;
137 qc = *pos & 0x0f;
138 aad_len += 2;
139 }
140 /* CCM Initial Block:
141 * Flag (Include authentication header, M=3 (8-octet MIC),
142 * L=1 (2-octet Dlen))
143 * Nonce: 0x00 | A2 | PN
144 * Dlen
145 */
146 b0[0] = 0x59;
147 b0[1] = qc;
148 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
149 memcpy(b0 + 8, pn, CCMP_PN_LEN);
150 b0[14] = (dlen >> 8) & 0xff;
151 b0[15] = dlen & 0xff;
152
153 /* AAD:
154 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
155 * A1 | A2 | A3
156 * SC with bits 4..15 (seq#) masked to zero
157 * A4 (if present)
158 * QC (if present)
159 */
160 pos = (u8 *)hdr;
161 aad[0] = 0; /* aad_len >> 8 */
162 aad[1] = aad_len & 0xff;
163 aad[2] = pos[0] & 0x8f;
164 aad[3] = pos[1] & 0xc7;
165 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
166 pos = (u8 *)&hdr->seq_ctl;
167 aad[22] = pos[0] & 0x0f;
168 aad[23] = 0; /* all bits masked */
169 memset(aad + 24, 0, 8);
170 if (a4_included)
171 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
172 if (qc_included) {
173 aad[a4_included ? 30 : 24] = qc;
174 /* rest of QC masked */
175 }
176
177 /* Start with the first block and AAD */
178 ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
179 xor_block(auth, aad, AES_BLOCK_LEN);
180 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
181 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
182 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
183 b0[0] &= 0x07;
184 b0[14] = 0;
185 b0[15] = 0;
186 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
187 }
188
ieee80211_ccmp_encrypt(struct sk_buff * skb,int hdr_len,void * priv)189 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
190 {
191 struct ieee80211_ccmp_data *key = priv;
192 int data_len, i;
193 u8 *pos;
194 struct rtl_80211_hdr_4addr *hdr;
195 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
196
197 if (skb_headroom(skb) < CCMP_HDR_LEN ||
198 skb_tailroom(skb) < CCMP_MIC_LEN ||
199 skb->len < hdr_len)
200 return -1;
201
202 data_len = skb->len - hdr_len;
203 pos = skb_push(skb, CCMP_HDR_LEN);
204 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
205 pos += hdr_len;
206 /* mic = skb_put(skb, CCMP_MIC_LEN); */
207
208 i = CCMP_PN_LEN - 1;
209 while (i >= 0) {
210 key->tx_pn[i]++;
211 if (key->tx_pn[i] != 0)
212 break;
213 i--;
214 }
215
216 *pos++ = key->tx_pn[5];
217 *pos++ = key->tx_pn[4];
218 *pos++ = 0;
219 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
220 *pos++ = key->tx_pn[3];
221 *pos++ = key->tx_pn[2];
222 *pos++ = key->tx_pn[1];
223 *pos++ = key->tx_pn[0];
224
225 hdr = (struct rtl_80211_hdr_4addr *)skb->data;
226 if (!tcb_desc->bHwSec) {
227 int blocks, last, len;
228 u8 *mic;
229 u8 *b0 = key->tx_b0;
230 u8 *b = key->tx_b;
231 u8 *e = key->tx_e;
232 u8 *s0 = key->tx_s0;
233
234 /* mic is moved to here by john */
235 mic = skb_put(skb, CCMP_MIC_LEN);
236
237 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
238
239 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
240 last = data_len % AES_BLOCK_LEN;
241
242 for (i = 1; i <= blocks; i++) {
243 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
244 /* Authentication */
245 xor_block(b, pos, len);
246 ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
247 /* Encryption, with counter */
248 b0[14] = (i >> 8) & 0xff;
249 b0[15] = i & 0xff;
250 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
251 xor_block(pos, e, len);
252 pos += len;
253 }
254
255 for (i = 0; i < CCMP_MIC_LEN; i++)
256 mic[i] = b[i] ^ s0[i];
257 }
258 return 0;
259 }
260
ieee80211_ccmp_decrypt(struct sk_buff * skb,int hdr_len,void * priv)261 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
262 {
263 struct ieee80211_ccmp_data *key = priv;
264 u8 keyidx, *pos;
265 struct rtl_80211_hdr_4addr *hdr;
266 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 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 rtl_80211_hdr_4addr *)skb->data;
275 pos = skb->data + hdr_len;
276 keyidx = pos[3];
277 if (!(keyidx & (1 << 5))) {
278 if (net_ratelimit()) {
279 netdev_dbg(skb->dev, "CCMP: received packet without ExtIV flag from %pM\n",
280 hdr->addr2);
281 }
282 key->dot11RSNAStatsCCMPFormatErrors++;
283 return -2;
284 }
285 keyidx >>= 6;
286 if (key->key_idx != keyidx) {
287 netdev_dbg(skb->dev, "CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
288 key->key_idx, keyidx, priv);
289 return -6;
290 }
291 if (!key->key_set) {
292 if (net_ratelimit()) {
293 netdev_dbg(skb->dev, "CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
294 hdr->addr2, keyidx);
295 }
296 return -3;
297 }
298
299 pn[0] = pos[7];
300 pn[1] = pos[6];
301 pn[2] = pos[5];
302 pn[3] = pos[4];
303 pn[4] = pos[1];
304 pn[5] = pos[0];
305 pos += 8;
306
307 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
308 if (net_ratelimit()) {
309 netdev_dbg(skb->dev, "CCMP: replay detected: STA=%pM previous PN %pm received PN %pm\n",
310 hdr->addr2, key->rx_pn, pn);
311 }
312 key->dot11RSNAStatsCCMPReplays++;
313 return -4;
314 }
315 if (!tcb_desc->bHwSec) {
316 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
317 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
318 u8 *b0 = key->rx_b0;
319 u8 *b = key->rx_b;
320 u8 *a = key->rx_a;
321 int i, blocks, last, len;
322
323 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
324 xor_block(mic, b, CCMP_MIC_LEN);
325
326 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
327 last = data_len % AES_BLOCK_LEN;
328
329 for (i = 1; i <= blocks; i++) {
330 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
331 /* Decrypt, with counter */
332 b0[14] = (i >> 8) & 0xff;
333 b0[15] = i & 0xff;
334 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
335 xor_block(pos, b, len);
336 /* Authentication */
337 xor_block(a, pos, len);
338 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
339 pos += len;
340 }
341
342 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
343 if (net_ratelimit()) {
344 netdev_dbg(skb->dev, "CCMP: decrypt failed: STA=%pM\n",
345 hdr->addr2);
346 }
347 key->dot11RSNAStatsCCMPDecryptErrors++;
348 return -5;
349 }
350
351 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
352 }
353 /* Remove hdr and MIC */
354 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
355 skb_pull(skb, CCMP_HDR_LEN);
356 skb_trim(skb, skb->len - CCMP_MIC_LEN);
357
358 return keyidx;
359 }
360
ieee80211_ccmp_set_key(void * key,int len,u8 * seq,void * priv)361 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
362 {
363 struct ieee80211_ccmp_data *data = priv;
364 int keyidx;
365 struct crypto_tfm *tfm = data->tfm;
366
367 keyidx = data->key_idx;
368 memset(data, 0, sizeof(*data));
369 data->key_idx = keyidx;
370 data->tfm = tfm;
371 if (len == CCMP_TK_LEN) {
372 memcpy(data->key, key, CCMP_TK_LEN);
373 data->key_set = 1;
374 if (seq) {
375 data->rx_pn[0] = seq[5];
376 data->rx_pn[1] = seq[4];
377 data->rx_pn[2] = seq[3];
378 data->rx_pn[3] = seq[2];
379 data->rx_pn[4] = seq[1];
380 data->rx_pn[5] = seq[0];
381 }
382 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
383 } else if (len == 0) {
384 data->key_set = 0;
385 } else {
386 return -1;
387 }
388
389 return 0;
390 }
391
ieee80211_ccmp_get_key(void * key,int len,u8 * seq,void * priv)392 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
393 {
394 struct ieee80211_ccmp_data *data = priv;
395
396 if (len < CCMP_TK_LEN)
397 return -1;
398
399 if (!data->key_set)
400 return 0;
401 memcpy(key, data->key, CCMP_TK_LEN);
402
403 if (seq) {
404 seq[0] = data->tx_pn[5];
405 seq[1] = data->tx_pn[4];
406 seq[2] = data->tx_pn[3];
407 seq[3] = data->tx_pn[2];
408 seq[4] = data->tx_pn[1];
409 seq[5] = data->tx_pn[0];
410 }
411
412 return CCMP_TK_LEN;
413 }
414
ieee80211_ccmp_print_stats(char * p,void * priv)415 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
416 {
417 struct ieee80211_ccmp_data *ccmp = priv;
418
419 p += sprintf(p, "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n",
420 ccmp->key_idx, ccmp->key_set,
421 ccmp->tx_pn, ccmp->rx_pn,
422 ccmp->dot11RSNAStatsCCMPFormatErrors,
423 ccmp->dot11RSNAStatsCCMPReplays,
424 ccmp->dot11RSNAStatsCCMPDecryptErrors);
425
426 return p;
427 }
428
429 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
430 .name = "CCMP",
431 .init = ieee80211_ccmp_init,
432 .deinit = ieee80211_ccmp_deinit,
433 .encrypt_mpdu = ieee80211_ccmp_encrypt,
434 .decrypt_mpdu = ieee80211_ccmp_decrypt,
435 .encrypt_msdu = NULL,
436 .decrypt_msdu = NULL,
437 .set_key = ieee80211_ccmp_set_key,
438 .get_key = ieee80211_ccmp_get_key,
439 .print_stats = ieee80211_ccmp_print_stats,
440 .extra_prefix_len = CCMP_HDR_LEN,
441 .extra_postfix_len = CCMP_MIC_LEN,
442 .owner = THIS_MODULE,
443 };
444
ieee80211_crypto_ccmp_init(void)445 int __init ieee80211_crypto_ccmp_init(void)
446 {
447 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
448 }
449
ieee80211_crypto_ccmp_exit(void)450 void __exit ieee80211_crypto_ccmp_exit(void)
451 {
452 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
453 }
454
