2 * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
4 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
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
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>
24 #include <linux/crypto.h>
26 #include <linux/scatterlist.h>
28 #define AES_BLOCK_LEN 16
29 #define CCMP_HDR_LEN 8
30 #define CCMP_MIC_LEN 8
31 #define CCMP_TK_LEN 16
34 struct rtllib_ccmp_data {
38 u8 tx_pn[CCMP_PN_LEN];
39 u8 rx_pn[CCMP_PN_LEN];
41 u32 dot11RSNAStatsCCMPFormatErrors;
42 u32 dot11RSNAStatsCCMPReplays;
43 u32 dot11RSNAStatsCCMPDecryptErrors;
47 struct crypto_tfm *tfm;
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];
55 static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
56 const u8 pt[16], u8 ct[16])
58 crypto_cipher_encrypt_one((void *)tfm, ct, pt);
61 static void *rtllib_ccmp_init(int key_idx)
63 struct rtllib_ccmp_data *priv;
65 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
68 priv->key_idx = key_idx;
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 "
82 crypto_free_cipher((void *)priv->tfm);
90 static void rtllib_ccmp_deinit(void *priv)
92 struct rtllib_ccmp_data *_priv = priv;
93 if (_priv && _priv->tfm)
94 crypto_free_cipher((void *)_priv->tfm);
99 static inline void xor_block(u8 *b, u8 *a, size_t len)
102 for (i = 0; i < len; i++)
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,
116 int a4_included, qc_included;
117 u8 aad[2 * AES_BLOCK_LEN];
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));
123 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
124 (WLAN_FC_GET_STYPE(fc) & 0x08));
126 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
127 (WLAN_FC_GET_STYPE(fc) & 0x80));
132 pos = (u8 *) &hdr->addr4;
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
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;
151 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
153 * SC with bits 4..15 (seq#) masked to zero
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);
168 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
170 aad[a4_included ? 30 : 24] = qc;
171 /* rest of QC masked */
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);
182 rtllib_ccmp_aes_encrypt(tfm, b0, s0);
187 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
189 struct rtllib_ccmp_data *key = priv;
192 struct rtllib_hdr_4addr *hdr;
193 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
195 if (skb_headroom(skb) < CCMP_HDR_LEN ||
196 skb_tailroom(skb) < CCMP_MIC_LEN ||
200 data_len = skb->len - hdr_len;
201 pos = skb_push(skb, CCMP_HDR_LEN);
202 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
208 if (key->tx_pn[i] != 0)
213 *pos++ = key->tx_pn[5];
214 *pos++ = key->tx_pn[4];
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];
223 hdr = (struct rtllib_hdr_4addr *) skb->data;
224 if (!tcb_desc->bHwSec) {
225 int blocks, last, len;
232 mic = skb_put(skb, CCMP_MIC_LEN);
234 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
237 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
238 last = data_len % AES_BLOCK_LEN;
240 for (i = 1; i <= blocks; i++) {
241 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
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;
248 rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
249 xor_block(pos, e, len);
253 for (i = 0; i < CCMP_MIC_LEN; i++)
254 mic[i] = b[i] ^ s0[i];
260 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
262 struct rtllib_ccmp_data *key = priv;
264 struct rtllib_hdr_4addr *hdr;
265 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
269 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
270 key->dot11RSNAStatsCCMPFormatErrors++;
274 hdr = (struct rtllib_hdr_4addr *) skb->data;
275 pos = skb->data + hdr_len;
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);
282 key->dot11RSNAStatsCCMPFormatErrors++;
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);
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);
307 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
308 key->dot11RSNAStatsCCMPReplays++;
311 if (!tcb_desc->bHwSec) {
312 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
314 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
318 int i, blocks, last, len;
321 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
322 xor_block(mic, b, CCMP_MIC_LEN);
324 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
325 last = data_len % AES_BLOCK_LEN;
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;
332 rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
333 xor_block(pos, b, len);
335 xor_block(a, pos, len);
336 rtllib_ccmp_aes_encrypt(key->tfm, a, a);
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);
345 key->dot11RSNAStatsCCMPDecryptErrors++;
349 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
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);
360 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
362 struct rtllib_ccmp_data *data = priv;
364 struct crypto_tfm *tfm = data->tfm;
366 keyidx = data->key_idx;
367 memset(data, 0, sizeof(*data));
368 data->key_idx = keyidx;
370 if (len == CCMP_TK_LEN) {
371 memcpy(data->key, key, CCMP_TK_LEN);
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];
381 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
391 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
393 struct rtllib_ccmp_data *data = priv;
395 if (len < CCMP_TK_LEN)
400 memcpy(key, data->key, CCMP_TK_LEN);
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];
415 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
417 struct rtllib_ccmp_data *ccmp = priv;
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);
429 static struct lib80211_crypto_ops rtllib_crypt_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,
446 int __init rtllib_crypto_ccmp_init(void)
448 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
452 void __exit rtllib_crypto_ccmp_exit(void)
454 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
457 module_init(rtllib_crypto_ccmp_init);
458 module_exit(rtllib_crypto_ccmp_exit);
460 MODULE_LICENSE("GPL");