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_ATOMIC);
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 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate crypto API aes\n");
86 crypto_free_cipher((void *)priv->tfm);
94 static void ieee80211_ccmp_deinit(void *priv)
96 struct ieee80211_ccmp_data *_priv = priv;
98 if (_priv && _priv->tfm)
99 crypto_free_cipher((void *)_priv->tfm);
104 static inline void xor_block(u8 *b, u8 *a, size_t len)
108 for (i = 0; i < len; i++)
114 static void ccmp_init_blocks(struct crypto_tfm *tfm,
115 struct rtl_80211_hdr_4addr *hdr,
116 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
122 int a4_included, qc_included;
123 u8 aad[2 * AES_BLOCK_LEN];
125 fc = le16_to_cpu(hdr->frame_ctl);
126 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
127 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
128 /* qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
129 * (WLAN_FC_GET_STYPE(fc) & 0x08));
131 /* fixed by David :2006.9.6 */
132 qc_included = (WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
133 (WLAN_FC_GET_STYPE(fc) & 0x80);
138 pos = (u8 *) &hdr->addr4;
144 /* CCM Initial Block:
145 * Flag (Include authentication header, M=3 (8-octet MIC),
146 * L=1 (2-octet Dlen))
147 * Nonce: 0x00 | A2 | PN
152 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
153 memcpy(b0 + 8, pn, CCMP_PN_LEN);
154 b0[14] = (dlen >> 8) & 0xff;
155 b0[15] = dlen & 0xff;
158 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
160 * SC with bits 4..15 (seq#) masked to zero
165 aad[0] = 0; /* aad_len >> 8 */
166 aad[1] = aad_len & 0xff;
167 aad[2] = pos[0] & 0x8f;
168 aad[3] = pos[1] & 0xc7;
169 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
170 pos = (u8 *) &hdr->seq_ctl;
171 aad[22] = pos[0] & 0x0f;
172 aad[23] = 0; /* all bits masked */
173 memset(aad + 24, 0, 8);
175 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
177 aad[a4_included ? 30 : 24] = qc;
178 /* rest of QC masked */
181 /* Start with the first block and AAD */
182 ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
183 xor_block(auth, aad, AES_BLOCK_LEN);
184 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
185 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
186 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
189 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
194 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
196 struct ieee80211_ccmp_data *key = priv;
199 struct rtl_80211_hdr_4addr *hdr;
200 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
202 if (skb_headroom(skb) < CCMP_HDR_LEN ||
203 skb_tailroom(skb) < CCMP_MIC_LEN ||
207 data_len = skb->len - hdr_len;
208 pos = skb_push(skb, CCMP_HDR_LEN);
209 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
211 /* mic = skb_put(skb, CCMP_MIC_LEN); */
216 if (key->tx_pn[i] != 0)
221 *pos++ = key->tx_pn[5];
222 *pos++ = key->tx_pn[4];
224 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
225 *pos++ = key->tx_pn[3];
226 *pos++ = key->tx_pn[2];
227 *pos++ = key->tx_pn[1];
228 *pos++ = key->tx_pn[0];
231 hdr = (struct rtl_80211_hdr_4addr *) skb->data;
232 if (!tcb_desc->bHwSec) {
233 int blocks, last, len;
240 /* mic is moved to here by john */
241 mic = skb_put(skb, CCMP_MIC_LEN);
243 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
245 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
246 last = data_len % AES_BLOCK_LEN;
248 for (i = 1; i <= blocks; i++) {
249 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
251 xor_block(b, pos, len);
252 ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
253 /* Encryption, with counter */
254 b0[14] = (i >> 8) & 0xff;
256 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
257 xor_block(pos, e, len);
261 for (i = 0; i < CCMP_MIC_LEN; i++)
262 mic[i] = b[i] ^ s0[i];
268 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
270 struct ieee80211_ccmp_data *key = priv;
272 struct rtl_80211_hdr_4addr *hdr;
273 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
276 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
277 key->dot11RSNAStatsCCMPFormatErrors++;
281 hdr = (struct rtl_80211_hdr_4addr *) skb->data;
282 pos = skb->data + hdr_len;
284 if (!(keyidx & (1 << 5))) {
285 if (net_ratelimit()) {
286 printk(KERN_DEBUG "CCMP: received packet without ExtIV flag from %pM\n",
289 key->dot11RSNAStatsCCMPFormatErrors++;
293 if (key->key_idx != keyidx) {
294 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
295 key->key_idx, keyidx, priv);
299 if (net_ratelimit()) {
300 printk(KERN_DEBUG "CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
314 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
315 if (net_ratelimit()) {
316 printk(KERN_DEBUG "CCMP: replay detected: STA=%pM previous PN %pm received PN %pm\n",
317 hdr->addr2, key->rx_pn, pn);
319 key->dot11RSNAStatsCCMPReplays++;
322 if (!tcb_desc->bHwSec) {
323 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
324 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
328 int i, blocks, last, len;
331 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
332 xor_block(mic, b, CCMP_MIC_LEN);
334 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
335 last = data_len % AES_BLOCK_LEN;
337 for (i = 1; i <= blocks; i++) {
338 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
339 /* Decrypt, with counter */
340 b0[14] = (i >> 8) & 0xff;
342 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
343 xor_block(pos, b, len);
345 xor_block(a, pos, len);
346 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
350 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
351 if (net_ratelimit()) {
352 printk(KERN_DEBUG "CCMP: decrypt failed: STA=%pM\n",
355 key->dot11RSNAStatsCCMPDecryptErrors++;
359 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
361 /* Remove hdr and MIC */
362 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
363 skb_pull(skb, CCMP_HDR_LEN);
364 skb_trim(skb, skb->len - CCMP_MIC_LEN);
370 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
372 struct ieee80211_ccmp_data *data = priv;
374 struct crypto_tfm *tfm = data->tfm;
376 keyidx = data->key_idx;
377 memset(data, 0, sizeof(*data));
378 data->key_idx = keyidx;
380 if (len == CCMP_TK_LEN) {
381 memcpy(data->key, key, CCMP_TK_LEN);
384 data->rx_pn[0] = seq[5];
385 data->rx_pn[1] = seq[4];
386 data->rx_pn[2] = seq[3];
387 data->rx_pn[3] = seq[2];
388 data->rx_pn[4] = seq[1];
389 data->rx_pn[5] = seq[0];
391 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
401 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
403 struct ieee80211_ccmp_data *data = priv;
405 if (len < CCMP_TK_LEN)
410 memcpy(key, data->key, CCMP_TK_LEN);
413 seq[0] = data->tx_pn[5];
414 seq[1] = data->tx_pn[4];
415 seq[2] = data->tx_pn[3];
416 seq[3] = data->tx_pn[2];
417 seq[4] = data->tx_pn[1];
418 seq[5] = data->tx_pn[0];
425 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
427 struct ieee80211_ccmp_data *ccmp = priv;
429 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",
430 ccmp->key_idx, ccmp->key_set,
431 ccmp->tx_pn, ccmp->rx_pn,
432 ccmp->dot11RSNAStatsCCMPFormatErrors,
433 ccmp->dot11RSNAStatsCCMPReplays,
434 ccmp->dot11RSNAStatsCCMPDecryptErrors);
439 void ieee80211_ccmp_null(void)
441 /* printk("============>%s()\n", __func__); */
445 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
447 .init = ieee80211_ccmp_init,
448 .deinit = ieee80211_ccmp_deinit,
449 .encrypt_mpdu = ieee80211_ccmp_encrypt,
450 .decrypt_mpdu = ieee80211_ccmp_decrypt,
451 .encrypt_msdu = NULL,
452 .decrypt_msdu = NULL,
453 .set_key = ieee80211_ccmp_set_key,
454 .get_key = ieee80211_ccmp_get_key,
455 .print_stats = ieee80211_ccmp_print_stats,
456 .extra_prefix_len = CCMP_HDR_LEN,
457 .extra_postfix_len = CCMP_MIC_LEN,
458 .owner = THIS_MODULE,
461 int __init ieee80211_crypto_ccmp_init(void)
463 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
466 void __exit ieee80211_crypto_ccmp_exit(void)
468 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);