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 pr_debug("Could not allocate crypto API aes\n");
81 crypto_free_cipher((void *)priv->tfm);
89 static void rtllib_ccmp_deinit(void *priv)
91 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)
103 for (i = 0; i < len; i++)
109 static void ccmp_init_blocks(struct crypto_tfm *tfm,
110 struct rtllib_hdr_4addr *hdr,
111 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
117 int a4_included, qc_included;
118 u8 aad[2 * AES_BLOCK_LEN];
120 fc = le16_to_cpu(hdr->frame_ctl);
121 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
122 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
124 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
125 (WLAN_FC_GET_STYPE(fc) & 0x80));
130 pos = (u8 *) &hdr->addr4;
136 /* CCM Initial Block:
137 * Flag (Include authentication header, M=3 (8-octet MIC),
138 * L=1 (2-octet Dlen))
139 * Nonce: 0x00 | A2 | PN
144 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
145 memcpy(b0 + 8, pn, CCMP_PN_LEN);
146 b0[14] = (dlen >> 8) & 0xff;
147 b0[15] = dlen & 0xff;
150 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
152 * SC with bits 4..15 (seq#) masked to zero
157 aad[0] = 0; /* aad_len >> 8 */
158 aad[1] = aad_len & 0xff;
159 aad[2] = pos[0] & 0x8f;
160 aad[3] = pos[1] & 0xc7;
161 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
162 pos = (u8 *) &hdr->seq_ctl;
163 aad[22] = pos[0] & 0x0f;
164 aad[23] = 0; /* all bits masked */
165 memset(aad + 24, 0, 8);
167 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
169 aad[a4_included ? 30 : 24] = qc;
170 /* rest of QC masked */
173 /* Start with the first block and AAD */
174 rtllib_ccmp_aes_encrypt(tfm, b0, auth);
175 xor_block(auth, aad, AES_BLOCK_LEN);
176 rtllib_ccmp_aes_encrypt(tfm, auth, auth);
177 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
178 rtllib_ccmp_aes_encrypt(tfm, auth, auth);
181 rtllib_ccmp_aes_encrypt(tfm, b0, s0);
186 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
188 struct rtllib_ccmp_data *key = priv;
191 struct rtllib_hdr_4addr *hdr;
192 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
194 if (skb_headroom(skb) < CCMP_HDR_LEN ||
195 skb_tailroom(skb) < CCMP_MIC_LEN ||
199 data_len = skb->len - hdr_len;
200 pos = skb_push(skb, CCMP_HDR_LEN);
201 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
207 if (key->tx_pn[i] != 0)
212 *pos++ = key->tx_pn[5];
213 *pos++ = key->tx_pn[4];
215 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
216 *pos++ = key->tx_pn[3];
217 *pos++ = key->tx_pn[2];
218 *pos++ = key->tx_pn[1];
219 *pos++ = key->tx_pn[0];
222 hdr = (struct rtllib_hdr_4addr *) skb->data;
223 if (!tcb_desc->bHwSec) {
224 int blocks, last, len;
231 mic = skb_put(skb, CCMP_MIC_LEN);
233 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
236 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
237 last = data_len % AES_BLOCK_LEN;
239 for (i = 1; i <= blocks; i++) {
240 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
242 xor_block(b, pos, len);
243 rtllib_ccmp_aes_encrypt(key->tfm, b, b);
244 /* Encryption, with counter */
245 b0[14] = (i >> 8) & 0xff;
247 rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
248 xor_block(pos, e, len);
252 for (i = 0; i < CCMP_MIC_LEN; i++)
253 mic[i] = b[i] ^ s0[i];
259 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
261 struct rtllib_ccmp_data *key = priv;
263 struct rtllib_hdr_4addr *hdr;
264 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
268 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
269 key->dot11RSNAStatsCCMPFormatErrors++;
273 hdr = (struct rtllib_hdr_4addr *) skb->data;
274 pos = skb->data + hdr_len;
276 if (!(keyidx & (1 << 5))) {
277 if (net_ratelimit()) {
278 pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
281 key->dot11RSNAStatsCCMPFormatErrors++;
285 if (key->key_idx != keyidx) {
286 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
287 key->key_idx, keyidx, priv);
291 if (net_ratelimit()) {
292 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
305 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
306 key->dot11RSNAStatsCCMPReplays++;
309 if (!tcb_desc->bHwSec) {
310 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
312 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
316 int i, blocks, last, len;
319 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
320 xor_block(mic, b, CCMP_MIC_LEN);
322 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
323 last = data_len % AES_BLOCK_LEN;
325 for (i = 1; i <= blocks; i++) {
326 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
327 /* Decrypt, with counter */
328 b0[14] = (i >> 8) & 0xff;
330 rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
331 xor_block(pos, b, len);
333 xor_block(a, pos, len);
334 rtllib_ccmp_aes_encrypt(key->tfm, a, a);
338 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
339 if (net_ratelimit()) {
340 pr_debug("CCMP: decrypt failed: STA= %pM\n",
343 key->dot11RSNAStatsCCMPDecryptErrors++;
347 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
349 /* Remove hdr and MIC */
350 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
351 skb_pull(skb, CCMP_HDR_LEN);
352 skb_trim(skb, skb->len - CCMP_MIC_LEN);
358 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
360 struct rtllib_ccmp_data *data = priv;
362 struct crypto_tfm *tfm = data->tfm;
364 keyidx = data->key_idx;
365 memset(data, 0, sizeof(*data));
366 data->key_idx = keyidx;
368 if (len == CCMP_TK_LEN) {
369 memcpy(data->key, key, CCMP_TK_LEN);
372 data->rx_pn[0] = seq[5];
373 data->rx_pn[1] = seq[4];
374 data->rx_pn[2] = seq[3];
375 data->rx_pn[3] = seq[2];
376 data->rx_pn[4] = seq[1];
377 data->rx_pn[5] = seq[0];
379 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
389 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
391 struct rtllib_ccmp_data *data = priv;
393 if (len < CCMP_TK_LEN)
398 memcpy(key, data->key, CCMP_TK_LEN);
401 seq[0] = data->tx_pn[5];
402 seq[1] = data->tx_pn[4];
403 seq[2] = data->tx_pn[3];
404 seq[3] = data->tx_pn[2];
405 seq[4] = data->tx_pn[1];
406 seq[5] = data->tx_pn[0];
413 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
415 struct rtllib_ccmp_data *ccmp = priv;
418 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
419 ccmp->key_idx, ccmp->key_set,
420 ccmp->tx_pn, ccmp->rx_pn,
421 ccmp->dot11RSNAStatsCCMPFormatErrors,
422 ccmp->dot11RSNAStatsCCMPReplays,
423 ccmp->dot11RSNAStatsCCMPDecryptErrors);
426 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
428 .init = rtllib_ccmp_init,
429 .deinit = rtllib_ccmp_deinit,
430 .encrypt_mpdu = rtllib_ccmp_encrypt,
431 .decrypt_mpdu = rtllib_ccmp_decrypt,
432 .encrypt_msdu = NULL,
433 .decrypt_msdu = NULL,
434 .set_key = rtllib_ccmp_set_key,
435 .get_key = rtllib_ccmp_get_key,
436 .print_stats = rtllib_ccmp_print_stats,
437 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
438 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
439 .owner = THIS_MODULE,
443 static int __init rtllib_crypto_ccmp_init(void)
445 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
449 static void __exit rtllib_crypto_ccmp_exit(void)
451 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
454 module_init(rtllib_crypto_ccmp_init);
455 module_exit(rtllib_crypto_ccmp_exit);
457 MODULE_LICENSE("GPL");