blob: 78b2d13e80e3638cba22d9a6f0bb7df727856829 [file] [log] [blame]
Jeff Garzikb4538722005-05-12 22:48:20 -04001/*
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>
Jeff Garzikb4538722005-05-12 22:48:20 -040013#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/slab.h>
16#include <linux/random.h>
17#include <linux/skbuff.h>
18#include <linux/netdevice.h>
19#include <linux/if_ether.h>
20#include <linux/if_arp.h>
21#include <asm/string.h>
22#include <linux/wireless.h>
23
24#include <net/ieee80211.h>
25
Jeff Garzikb4538722005-05-12 22:48:20 -040026#include <linux/crypto.h>
27#include <asm/scatterlist.h>
28
29MODULE_AUTHOR("Jouni Malinen");
30MODULE_DESCRIPTION("Host AP crypt: CCMP");
31MODULE_LICENSE("GPL");
32
33#define AES_BLOCK_LEN 16
34#define CCMP_HDR_LEN 8
35#define CCMP_MIC_LEN 8
36#define CCMP_TK_LEN 16
37#define CCMP_PN_LEN 6
38
39struct ieee80211_ccmp_data {
40 u8 key[CCMP_TK_LEN];
41 int key_set;
42
43 u8 tx_pn[CCMP_PN_LEN];
44 u8 rx_pn[CCMP_PN_LEN];
45
46 u32 dot11RSNAStatsCCMPFormatErrors;
47 u32 dot11RSNAStatsCCMPReplays;
48 u32 dot11RSNAStatsCCMPDecryptErrors;
49
50 int key_idx;
51
52 struct crypto_tfm *tfm;
53
54 /* scratch buffers for virt_to_page() (crypto API) */
55 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
Jeff Garzik0edd5b42005-09-07 00:48:31 -040056 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
Jeff Garzikb4538722005-05-12 22:48:20 -040057 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
58};
59
Adrian Bunke1572492005-05-06 23:32:39 +020060static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
61 const u8 pt[16], u8 ct[16])
Jeff Garzikb4538722005-05-12 22:48:20 -040062{
63 struct scatterlist src, dst;
64
65 src.page = virt_to_page(pt);
66 src.offset = offset_in_page(pt);
67 src.length = AES_BLOCK_LEN;
68
69 dst.page = virt_to_page(ct);
70 dst.offset = offset_in_page(ct);
71 dst.length = AES_BLOCK_LEN;
72
73 crypto_cipher_encrypt(tfm, &dst, &src, AES_BLOCK_LEN);
74}
75
James Ketrenos6eb6edf2005-09-22 10:34:15 +000076static void *ieee80211_ccmp_init(int key_idx)
Jeff Garzikb4538722005-05-12 22:48:20 -040077{
78 struct ieee80211_ccmp_data *priv;
79
80 priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
81 if (priv == NULL)
82 goto fail;
83 memset(priv, 0, sizeof(*priv));
84 priv->key_idx = key_idx;
85
86 priv->tfm = crypto_alloc_tfm("aes", 0);
87 if (priv->tfm == NULL) {
88 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
89 "crypto API aes\n");
90 goto fail;
91 }
92
93 return priv;
94
Jeff Garzik0edd5b42005-09-07 00:48:31 -040095 fail:
Jeff Garzikb4538722005-05-12 22:48:20 -040096 if (priv) {
97 if (priv->tfm)
98 crypto_free_tfm(priv->tfm);
99 kfree(priv);
100 }
101
102 return NULL;
103}
104
Jeff Garzikb4538722005-05-12 22:48:20 -0400105static void ieee80211_ccmp_deinit(void *priv)
106{
107 struct ieee80211_ccmp_data *_priv = priv;
108 if (_priv && _priv->tfm)
109 crypto_free_tfm(_priv->tfm);
110 kfree(priv);
111}
112
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400113static inline void xor_block(u8 * b, u8 * a, size_t len)
Jeff Garzikb4538722005-05-12 22:48:20 -0400114{
115 int i;
116 for (i = 0; i < len; i++)
117 b[i] ^= a[i];
118}
119
Jeff Garzikb4538722005-05-12 22:48:20 -0400120static void ccmp_init_blocks(struct crypto_tfm *tfm,
James Ketrenosee34af32005-09-21 11:54:36 -0500121 struct ieee80211_hdr_4addr *hdr,
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400122 u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0)
Jeff Garzikb4538722005-05-12 22:48:20 -0400123{
124 u8 *pos, qc = 0;
125 size_t aad_len;
126 u16 fc;
127 int a4_included, qc_included;
128 u8 aad[2 * AES_BLOCK_LEN];
129
130 fc = le16_to_cpu(hdr->frame_ctl);
131 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
132 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
133 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
Zhu Yi0df78612006-02-28 15:10:36 +0800134 (WLAN_FC_GET_STYPE(fc) & IEEE80211_STYPE_QOS_DATA));
Jeff Garzikb4538722005-05-12 22:48:20 -0400135 aad_len = 22;
136 if (a4_included)
137 aad_len += 6;
138 if (qc_included) {
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400139 pos = (u8 *) & hdr->addr4;
Jeff Garzikb4538722005-05-12 22:48:20 -0400140 if (a4_included)
141 pos += 6;
142 qc = *pos & 0x0f;
143 aad_len += 2;
144 }
145
146 /* CCM Initial Block:
147 * Flag (Include authentication header, M=3 (8-octet MIC),
148 * L=1 (2-octet Dlen))
149 * Nonce: 0x00 | A2 | PN
150 * Dlen */
151 b0[0] = 0x59;
152 b0[1] = qc;
153 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
154 memcpy(b0 + 8, pn, CCMP_PN_LEN);
155 b0[14] = (dlen >> 8) & 0xff;
156 b0[15] = dlen & 0xff;
157
158 /* AAD:
159 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
160 * A1 | A2 | A3
161 * SC with bits 4..15 (seq#) masked to zero
162 * A4 (if present)
163 * QC (if present)
164 */
165 pos = (u8 *) hdr;
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400166 aad[0] = 0; /* aad_len >> 8 */
Jeff Garzikb4538722005-05-12 22:48:20 -0400167 aad[1] = aad_len & 0xff;
168 aad[2] = pos[0] & 0x8f;
169 aad[3] = pos[1] & 0xc7;
170 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400171 pos = (u8 *) & hdr->seq_ctl;
Jeff Garzikb4538722005-05-12 22:48:20 -0400172 aad[22] = pos[0] & 0x0f;
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400173 aad[23] = 0; /* all bits masked */
Jeff Garzikb4538722005-05-12 22:48:20 -0400174 memset(aad + 24, 0, 8);
175 if (a4_included)
176 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
177 if (qc_included) {
178 aad[a4_included ? 30 : 24] = qc;
179 /* rest of QC masked */
180 }
181
182 /* Start with the first block and AAD */
183 ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
184 xor_block(auth, aad, AES_BLOCK_LEN);
185 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
186 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
187 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
188 b0[0] &= 0x07;
189 b0[14] = b0[15] = 0;
190 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
191}
192
Zhu Yi9184d932006-01-19 16:22:32 +0800193static int ieee80211_ccmp_hdr(struct sk_buff *skb, int hdr_len,
194 u8 *aeskey, int keylen, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400195{
196 struct ieee80211_ccmp_data *key = priv;
James Ketrenos31b59ea2005-09-21 11:58:49 -0500197 int i;
198 u8 *pos;
Jeff Garzikb4538722005-05-12 22:48:20 -0400199
James Ketrenos31b59ea2005-09-21 11:58:49 -0500200 if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
Jeff Garzikb4538722005-05-12 22:48:20 -0400201 return -1;
202
Zhu Yi9184d932006-01-19 16:22:32 +0800203 if (aeskey != NULL && keylen >= CCMP_TK_LEN)
204 memcpy(aeskey, key->key, CCMP_TK_LEN);
205
Jeff Garzikb4538722005-05-12 22:48:20 -0400206 pos = skb_push(skb, CCMP_HDR_LEN);
207 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
208 pos += hdr_len;
Jeff Garzikb4538722005-05-12 22:48:20 -0400209
210 i = CCMP_PN_LEN - 1;
211 while (i >= 0) {
212 key->tx_pn[i]++;
213 if (key->tx_pn[i] != 0)
214 break;
215 i--;
216 }
217
218 *pos++ = key->tx_pn[5];
219 *pos++ = key->tx_pn[4];
220 *pos++ = 0;
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400221 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
Jeff Garzikb4538722005-05-12 22:48:20 -0400222 *pos++ = key->tx_pn[3];
223 *pos++ = key->tx_pn[2];
224 *pos++ = key->tx_pn[1];
225 *pos++ = key->tx_pn[0];
226
James Ketrenos31b59ea2005-09-21 11:58:49 -0500227 return CCMP_HDR_LEN;
228}
229
230static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
231{
232 struct ieee80211_ccmp_data *key = priv;
233 int data_len, i, blocks, last, len;
234 u8 *pos, *mic;
235 struct ieee80211_hdr_4addr *hdr;
236 u8 *b0 = key->tx_b0;
237 u8 *b = key->tx_b;
238 u8 *e = key->tx_e;
239 u8 *s0 = key->tx_s0;
240
241 if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
242 return -1;
243
244 data_len = skb->len - hdr_len;
Zhu Yi9184d932006-01-19 16:22:32 +0800245 len = ieee80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
James Ketrenos31b59ea2005-09-21 11:58:49 -0500246 if (len < 0)
247 return -1;
248
249 pos = skb->data + hdr_len + CCMP_HDR_LEN;
250 mic = skb_put(skb, CCMP_MIC_LEN);
James Ketrenosee34af32005-09-21 11:54:36 -0500251 hdr = (struct ieee80211_hdr_4addr *)skb->data;
Jeff Garzikb4538722005-05-12 22:48:20 -0400252 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
253
254 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
255 last = data_len % AES_BLOCK_LEN;
256
257 for (i = 1; i <= blocks; i++) {
258 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
259 /* Authentication */
260 xor_block(b, pos, len);
261 ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
262 /* Encryption, with counter */
263 b0[14] = (i >> 8) & 0xff;
264 b0[15] = i & 0xff;
265 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
266 xor_block(pos, e, len);
267 pos += len;
268 }
269
270 for (i = 0; i < CCMP_MIC_LEN; i++)
271 mic[i] = b[i] ^ s0[i];
272
273 return 0;
274}
275
Jeff Garzikb4538722005-05-12 22:48:20 -0400276static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
277{
278 struct ieee80211_ccmp_data *key = priv;
279 u8 keyidx, *pos;
James Ketrenosee34af32005-09-21 11:54:36 -0500280 struct ieee80211_hdr_4addr *hdr;
Jeff Garzikb4538722005-05-12 22:48:20 -0400281 u8 *b0 = key->rx_b0;
282 u8 *b = key->rx_b;
283 u8 *a = key->rx_a;
284 u8 pn[6];
285 int i, blocks, last, len;
286 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
287 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
288
289 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
290 key->dot11RSNAStatsCCMPFormatErrors++;
291 return -1;
292 }
293
James Ketrenosee34af32005-09-21 11:54:36 -0500294 hdr = (struct ieee80211_hdr_4addr *)skb->data;
Jeff Garzikb4538722005-05-12 22:48:20 -0400295 pos = skb->data + hdr_len;
296 keyidx = pos[3];
297 if (!(keyidx & (1 << 5))) {
298 if (net_ratelimit()) {
299 printk(KERN_DEBUG "CCMP: received packet without ExtIV"
300 " flag from " MAC_FMT "\n", MAC_ARG(hdr->addr2));
301 }
302 key->dot11RSNAStatsCCMPFormatErrors++;
303 return -2;
304 }
305 keyidx >>= 6;
306 if (key->key_idx != keyidx) {
307 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
308 "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
309 return -6;
310 }
311 if (!key->key_set) {
312 if (net_ratelimit()) {
313 printk(KERN_DEBUG "CCMP: received packet from " MAC_FMT
314 " with keyid=%d that does not have a configured"
315 " key\n", MAC_ARG(hdr->addr2), keyidx);
316 }
317 return -3;
318 }
319
320 pn[0] = pos[7];
321 pn[1] = pos[6];
322 pn[2] = pos[5];
323 pn[3] = pos[4];
324 pn[4] = pos[1];
325 pn[5] = pos[0];
326 pos += 8;
327
328 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
329 if (net_ratelimit()) {
330 printk(KERN_DEBUG "CCMP: replay detected: STA=" MAC_FMT
331 " previous PN %02x%02x%02x%02x%02x%02x "
332 "received PN %02x%02x%02x%02x%02x%02x\n",
333 MAC_ARG(hdr->addr2), MAC_ARG(key->rx_pn),
334 MAC_ARG(pn));
335 }
336 key->dot11RSNAStatsCCMPReplays++;
337 return -4;
338 }
339
340 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
341 xor_block(mic, b, CCMP_MIC_LEN);
342
343 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
344 last = data_len % AES_BLOCK_LEN;
345
346 for (i = 1; i <= blocks; i++) {
347 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
348 /* Decrypt, with counter */
349 b0[14] = (i >> 8) & 0xff;
350 b0[15] = i & 0xff;
351 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
352 xor_block(pos, b, len);
353 /* Authentication */
354 xor_block(a, pos, len);
355 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
356 pos += len;
357 }
358
359 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
360 if (net_ratelimit()) {
361 printk(KERN_DEBUG "CCMP: decrypt failed: STA="
362 MAC_FMT "\n", MAC_ARG(hdr->addr2));
363 }
364 key->dot11RSNAStatsCCMPDecryptErrors++;
365 return -5;
366 }
367
368 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
369
370 /* Remove hdr and MIC */
371 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
372 skb_pull(skb, CCMP_HDR_LEN);
373 skb_trim(skb, skb->len - CCMP_MIC_LEN);
374
375 return keyidx;
376}
377
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400378static int ieee80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400379{
380 struct ieee80211_ccmp_data *data = priv;
381 int keyidx;
382 struct crypto_tfm *tfm = data->tfm;
383
384 keyidx = data->key_idx;
385 memset(data, 0, sizeof(*data));
386 data->key_idx = keyidx;
387 data->tfm = tfm;
388 if (len == CCMP_TK_LEN) {
389 memcpy(data->key, key, CCMP_TK_LEN);
390 data->key_set = 1;
391 if (seq) {
392 data->rx_pn[0] = seq[5];
393 data->rx_pn[1] = seq[4];
394 data->rx_pn[2] = seq[3];
395 data->rx_pn[3] = seq[2];
396 data->rx_pn[4] = seq[1];
397 data->rx_pn[5] = seq[0];
398 }
399 crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN);
400 } else if (len == 0)
401 data->key_set = 0;
402 else
403 return -1;
404
405 return 0;
406}
407
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400408static int ieee80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400409{
410 struct ieee80211_ccmp_data *data = priv;
411
412 if (len < CCMP_TK_LEN)
413 return -1;
414
415 if (!data->key_set)
416 return 0;
417 memcpy(key, data->key, CCMP_TK_LEN);
418
419 if (seq) {
420 seq[0] = data->tx_pn[5];
421 seq[1] = data->tx_pn[4];
422 seq[2] = data->tx_pn[3];
423 seq[3] = data->tx_pn[2];
424 seq[4] = data->tx_pn[1];
425 seq[5] = data->tx_pn[0];
426 }
427
428 return CCMP_TK_LEN;
429}
430
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400431static char *ieee80211_ccmp_print_stats(char *p, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400432{
433 struct ieee80211_ccmp_data *ccmp = priv;
434 p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
435 "tx_pn=%02x%02x%02x%02x%02x%02x "
436 "rx_pn=%02x%02x%02x%02x%02x%02x "
437 "format_errors=%d replays=%d decrypt_errors=%d\n",
438 ccmp->key_idx, ccmp->key_set,
439 MAC_ARG(ccmp->tx_pn), MAC_ARG(ccmp->rx_pn),
440 ccmp->dot11RSNAStatsCCMPFormatErrors,
441 ccmp->dot11RSNAStatsCCMPReplays,
442 ccmp->dot11RSNAStatsCCMPDecryptErrors);
443
444 return p;
445}
446
Jeff Garzikb4538722005-05-12 22:48:20 -0400447static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
James Ketrenos74079fd2005-09-13 17:35:21 -0500448 .name = "CCMP",
449 .init = ieee80211_ccmp_init,
450 .deinit = ieee80211_ccmp_deinit,
James Ketrenos31b59ea2005-09-21 11:58:49 -0500451 .build_iv = ieee80211_ccmp_hdr,
James Ketrenos74079fd2005-09-13 17:35:21 -0500452 .encrypt_mpdu = ieee80211_ccmp_encrypt,
453 .decrypt_mpdu = ieee80211_ccmp_decrypt,
454 .encrypt_msdu = NULL,
455 .decrypt_msdu = NULL,
456 .set_key = ieee80211_ccmp_set_key,
457 .get_key = ieee80211_ccmp_get_key,
458 .print_stats = ieee80211_ccmp_print_stats,
James Ketrenos1264fc02005-09-21 11:54:53 -0500459 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
460 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
James Ketrenos74079fd2005-09-13 17:35:21 -0500461 .owner = THIS_MODULE,
Jeff Garzikb4538722005-05-12 22:48:20 -0400462};
463
Jeff Garzikb4538722005-05-12 22:48:20 -0400464static int __init ieee80211_crypto_ccmp_init(void)
465{
466 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
467}
468
Jeff Garzikb4538722005-05-12 22:48:20 -0400469static void __exit ieee80211_crypto_ccmp_exit(void)
470{
471 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
472}
473
Jeff Garzikb4538722005-05-12 22:48:20 -0400474module_init(ieee80211_crypto_ccmp_init);
475module_exit(ieee80211_crypto_ccmp_exit);