2 * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
4 * Copyright (c) 2003-2004, Jouni Malinen <j@w1.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/kernel.h>
13 #include <linux/err.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/random.h>
18 #include <linux/skbuff.h>
19 #include <linux/netdevice.h>
20 #include <linux/if_ether.h>
21 #include <linux/if_arp.h>
22 #include <asm/string.h>
23 #include <linux/wireless.h>
25 #include <net/ieee80211.h>
27 #include <linux/crypto.h>
28 #include <asm/scatterlist.h>
30 MODULE_AUTHOR("Jouni Malinen");
31 MODULE_DESCRIPTION("Host AP crypt: CCMP");
32 MODULE_LICENSE("GPL");
34 #define AES_BLOCK_LEN 16
35 #define CCMP_HDR_LEN 8
36 #define CCMP_MIC_LEN 8
37 #define CCMP_TK_LEN 16
40 struct ieee80211_ccmp_data {
44 u8 tx_pn[CCMP_PN_LEN];
45 u8 rx_pn[CCMP_PN_LEN];
47 u32 dot11RSNAStatsCCMPFormatErrors;
48 u32 dot11RSNAStatsCCMPReplays;
49 u32 dot11RSNAStatsCCMPDecryptErrors;
53 struct crypto_cipher *tfm;
55 /* scratch buffers for virt_to_page() (crypto API) */
56 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
57 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
58 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
61 static inline void ieee80211_ccmp_aes_encrypt(struct crypto_cipher *tfm,
62 const u8 pt[16], u8 ct[16])
64 crypto_cipher_encrypt_one(tfm, ct, pt);
67 static void *ieee80211_ccmp_init(int key_idx)
69 struct ieee80211_ccmp_data *priv;
71 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
74 priv->key_idx = key_idx;
76 priv->tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
77 if (IS_ERR(priv->tfm)) {
78 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
89 crypto_free_cipher(priv->tfm);
96 static void ieee80211_ccmp_deinit(void *priv)
98 struct ieee80211_ccmp_data *_priv = priv;
99 if (_priv && _priv->tfm)
100 crypto_free_cipher(_priv->tfm);
104 static inline void xor_block(u8 * b, u8 * a, size_t len)
107 for (i = 0; i < len; i++)
111 static void ccmp_init_blocks(struct crypto_cipher *tfm,
112 struct ieee80211_hdr_4addr *hdr,
113 u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0)
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) & IEEE80211_STYPE_QOS_DATA));
130 pos = (u8 *) & hdr->addr4;
137 /* CCM Initial Block:
138 * Flag (Include authentication header, M=3 (8-octet MIC),
139 * L=1 (2-octet Dlen))
140 * 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 ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
175 xor_block(auth, aad, AES_BLOCK_LEN);
176 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
177 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
178 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
181 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
184 static int ieee80211_ccmp_hdr(struct sk_buff *skb, int hdr_len,
185 u8 *aeskey, int keylen, void *priv)
187 struct ieee80211_ccmp_data *key = priv;
191 if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
194 if (aeskey != NULL && keylen >= CCMP_TK_LEN)
195 memcpy(aeskey, key->key, CCMP_TK_LEN);
197 pos = skb_push(skb, CCMP_HDR_LEN);
198 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
204 if (key->tx_pn[i] != 0)
209 *pos++ = key->tx_pn[5];
210 *pos++ = key->tx_pn[4];
212 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
213 *pos++ = key->tx_pn[3];
214 *pos++ = key->tx_pn[2];
215 *pos++ = key->tx_pn[1];
216 *pos++ = key->tx_pn[0];
221 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
223 struct ieee80211_ccmp_data *key = priv;
224 int data_len, i, blocks, last, len;
226 struct ieee80211_hdr_4addr *hdr;
232 if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
235 data_len = skb->len - hdr_len;
236 len = ieee80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
240 pos = skb->data + hdr_len + CCMP_HDR_LEN;
241 mic = skb_put(skb, CCMP_MIC_LEN);
242 hdr = (struct ieee80211_hdr_4addr *)skb->data;
243 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
245 blocks = DIV_ROUND_UP(data_len, 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 * deal with seq counter wrapping correctly.
269 * refer to timer_after() for jiffies wrapping handling
271 static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
276 iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
277 iv16_n = (pn_n[4] << 8) | pn_n[5];
279 iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
280 iv16_o = (pn_o[4] << 8) | pn_o[5];
282 if ((s32)iv32_n - (s32)iv32_o < 0 ||
283 (iv32_n == iv32_o && iv16_n <= iv16_o))
288 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
290 struct ieee80211_ccmp_data *key = priv;
292 struct ieee80211_hdr_4addr *hdr;
297 int i, blocks, last, len;
298 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
299 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
301 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
302 key->dot11RSNAStatsCCMPFormatErrors++;
306 hdr = (struct ieee80211_hdr_4addr *)skb->data;
307 pos = skb->data + hdr_len;
309 if (!(keyidx & (1 << 5))) {
310 if (net_ratelimit()) {
311 printk(KERN_DEBUG "CCMP: received packet without ExtIV"
312 " flag from " MAC_FMT "\n", MAC_ARG(hdr->addr2));
314 key->dot11RSNAStatsCCMPFormatErrors++;
318 if (key->key_idx != keyidx) {
319 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
320 "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
324 if (net_ratelimit()) {
325 printk(KERN_DEBUG "CCMP: received packet from " MAC_FMT
326 " with keyid=%d that does not have a configured"
327 " key\n", MAC_ARG(hdr->addr2), keyidx);
340 if (ccmp_replay_check(pn, key->rx_pn)) {
341 if (net_ratelimit()) {
342 IEEE80211_DEBUG_DROP("CCMP: replay detected: STA=" MAC_FMT
343 " previous PN %02x%02x%02x%02x%02x%02x "
344 "received PN %02x%02x%02x%02x%02x%02x\n",
345 MAC_ARG(hdr->addr2), MAC_ARG(key->rx_pn),
348 key->dot11RSNAStatsCCMPReplays++;
352 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
353 xor_block(mic, b, CCMP_MIC_LEN);
355 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
356 last = data_len % AES_BLOCK_LEN;
358 for (i = 1; i <= blocks; i++) {
359 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
360 /* Decrypt, with counter */
361 b0[14] = (i >> 8) & 0xff;
363 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
364 xor_block(pos, b, len);
366 xor_block(a, pos, len);
367 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
371 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
372 if (net_ratelimit()) {
373 printk(KERN_DEBUG "CCMP: decrypt failed: STA="
374 MAC_FMT "\n", MAC_ARG(hdr->addr2));
376 key->dot11RSNAStatsCCMPDecryptErrors++;
380 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
382 /* Remove hdr and MIC */
383 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
384 skb_pull(skb, CCMP_HDR_LEN);
385 skb_trim(skb, skb->len - CCMP_MIC_LEN);
390 static int ieee80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
392 struct ieee80211_ccmp_data *data = priv;
394 struct crypto_cipher *tfm = data->tfm;
396 keyidx = data->key_idx;
397 memset(data, 0, sizeof(*data));
398 data->key_idx = keyidx;
400 if (len == CCMP_TK_LEN) {
401 memcpy(data->key, key, CCMP_TK_LEN);
404 data->rx_pn[0] = seq[5];
405 data->rx_pn[1] = seq[4];
406 data->rx_pn[2] = seq[3];
407 data->rx_pn[3] = seq[2];
408 data->rx_pn[4] = seq[1];
409 data->rx_pn[5] = seq[0];
411 crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN);
420 static int ieee80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
422 struct ieee80211_ccmp_data *data = priv;
424 if (len < CCMP_TK_LEN)
429 memcpy(key, data->key, CCMP_TK_LEN);
432 seq[0] = data->tx_pn[5];
433 seq[1] = data->tx_pn[4];
434 seq[2] = data->tx_pn[3];
435 seq[3] = data->tx_pn[2];
436 seq[4] = data->tx_pn[1];
437 seq[5] = data->tx_pn[0];
443 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
445 struct ieee80211_ccmp_data *ccmp = priv;
446 p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
447 "tx_pn=%02x%02x%02x%02x%02x%02x "
448 "rx_pn=%02x%02x%02x%02x%02x%02x "
449 "format_errors=%d replays=%d decrypt_errors=%d\n",
450 ccmp->key_idx, ccmp->key_set,
451 MAC_ARG(ccmp->tx_pn), MAC_ARG(ccmp->rx_pn),
452 ccmp->dot11RSNAStatsCCMPFormatErrors,
453 ccmp->dot11RSNAStatsCCMPReplays,
454 ccmp->dot11RSNAStatsCCMPDecryptErrors);
459 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
461 .init = ieee80211_ccmp_init,
462 .deinit = ieee80211_ccmp_deinit,
463 .build_iv = ieee80211_ccmp_hdr,
464 .encrypt_mpdu = ieee80211_ccmp_encrypt,
465 .decrypt_mpdu = ieee80211_ccmp_decrypt,
466 .encrypt_msdu = NULL,
467 .decrypt_msdu = NULL,
468 .set_key = ieee80211_ccmp_set_key,
469 .get_key = ieee80211_ccmp_get_key,
470 .print_stats = ieee80211_ccmp_print_stats,
471 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
472 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
473 .owner = THIS_MODULE,
476 static int __init ieee80211_crypto_ccmp_init(void)
478 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
481 static void __exit ieee80211_crypto_ccmp_exit(void)
483 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
486 module_init(ieee80211_crypto_ccmp_init);
487 module_exit(ieee80211_crypto_ccmp_exit);