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>
23 #include "ieee80211.h"
25 #include <linux/crypto.h>
26 #include <linux/scatterlist.h>
28 MODULE_AUTHOR("Jouni Malinen");
29 MODULE_DESCRIPTION("Host AP crypt: CCMP");
30 MODULE_LICENSE("GPL");
32 #define AES_BLOCK_LEN 16
33 #define CCMP_HDR_LEN 8
34 #define CCMP_MIC_LEN 8
35 #define CCMP_TK_LEN 16
38 struct ieee80211_ccmp_data {
42 u8 tx_pn[CCMP_PN_LEN];
43 u8 rx_pn[CCMP_PN_LEN];
45 u32 dot11RSNAStatsCCMPFormatErrors;
46 u32 dot11RSNAStatsCCMPReplays;
47 u32 dot11RSNAStatsCCMPDecryptErrors;
51 struct crypto_tfm *tfm;
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];
59 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
60 const u8 pt[16], u8 ct[16])
62 crypto_cipher_encrypt_one((void *)tfm, ct, pt);
65 static void *ieee80211_ccmp_init(int key_idx)
67 struct ieee80211_ccmp_data *priv;
69 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
72 priv->key_idx = key_idx;
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");
86 crypto_free_cipher((void *)priv->tfm);
93 static void ieee80211_ccmp_deinit(void *priv)
95 struct ieee80211_ccmp_data *_priv = priv;
97 if (_priv && _priv->tfm)
98 crypto_free_cipher((void *)_priv->tfm);
102 static inline void xor_block(u8 *b, u8 *a, size_t len)
106 for (i = 0; i < len; i++)
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,
118 int a4_included, qc_included;
119 u8 aad[2 * AES_BLOCK_LEN];
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));
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);
134 pos = (u8 *)&hdr->addr4;
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
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;
154 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
156 * SC with bits 4..15 (seq#) masked to zero
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);
171 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
173 aad[a4_included ? 30 : 24] = qc;
174 /* rest of QC masked */
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);
186 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
189 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
191 struct ieee80211_ccmp_data *key = priv;
194 struct rtl_80211_hdr_4addr *hdr;
195 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
197 if (skb_headroom(skb) < CCMP_HDR_LEN ||
198 skb_tailroom(skb) < CCMP_MIC_LEN ||
202 data_len = skb->len - hdr_len;
203 pos = skb_push(skb, CCMP_HDR_LEN);
204 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
206 /* mic = skb_put(skb, CCMP_MIC_LEN); */
211 if (key->tx_pn[i] != 0)
216 *pos++ = key->tx_pn[5];
217 *pos++ = key->tx_pn[4];
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];
225 hdr = (struct rtl_80211_hdr_4addr *)skb->data;
226 if (!tcb_desc->bHwSec) {
227 int blocks, last, len;
234 /* mic is moved to here by john */
235 mic = skb_put(skb, CCMP_MIC_LEN);
237 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
239 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
240 last = data_len % AES_BLOCK_LEN;
242 for (i = 1; i <= blocks; i++) {
243 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
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;
250 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
251 xor_block(pos, e, len);
255 for (i = 0; i < CCMP_MIC_LEN; i++)
256 mic[i] = b[i] ^ s0[i];
261 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
263 struct ieee80211_ccmp_data *key = priv;
265 struct rtl_80211_hdr_4addr *hdr;
266 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
269 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
270 key->dot11RSNAStatsCCMPFormatErrors++;
274 hdr = (struct rtl_80211_hdr_4addr *)skb->data;
275 pos = skb->data + hdr_len;
277 if (!(keyidx & (1 << 5))) {
278 if (net_ratelimit()) {
279 netdev_dbg(skb->dev, "CCMP: received packet without ExtIV flag from %pM\n",
282 key->dot11RSNAStatsCCMPFormatErrors++;
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);
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",
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);
312 key->dot11RSNAStatsCCMPReplays++;
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;
321 int i, blocks, last, len;
323 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
324 xor_block(mic, b, CCMP_MIC_LEN);
326 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
327 last = data_len % AES_BLOCK_LEN;
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;
334 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
335 xor_block(pos, b, len);
337 xor_block(a, pos, len);
338 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
342 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
343 if (net_ratelimit()) {
344 netdev_dbg(skb->dev, "CCMP: decrypt failed: STA=%pM\n",
347 key->dot11RSNAStatsCCMPDecryptErrors++;
351 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
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);
361 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
363 struct ieee80211_ccmp_data *data = priv;
365 struct crypto_tfm *tfm = data->tfm;
367 keyidx = data->key_idx;
368 memset(data, 0, sizeof(*data));
369 data->key_idx = keyidx;
371 if (len == CCMP_TK_LEN) {
372 memcpy(data->key, key, CCMP_TK_LEN);
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];
382 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
383 } else if (len == 0) {
392 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
394 struct ieee80211_ccmp_data *data = priv;
396 if (len < CCMP_TK_LEN)
401 memcpy(key, data->key, CCMP_TK_LEN);
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];
415 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
417 struct ieee80211_ccmp_data *ccmp = priv;
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);
429 static struct ieee80211_crypto_ops ieee80211_crypt_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,
445 int __init ieee80211_crypto_ccmp_init(void)
447 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
450 void __exit ieee80211_crypto_ccmp_exit(void)
452 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);