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 char *rtllib_ccmp_print_stats(char *p
, void *priv
)
417 struct rtllib_ccmp_data
*ccmp
= priv
;
418 p
+= sprintf(p
, "key[%d] alg=CCMP key_set=%d "
419 "tx_pn=%pM rx_pn=%pM "
420 "format_errors=%d replays=%d decrypt_errors=%d\n",
421 ccmp
->key_idx
, ccmp
->key_set
,
422 ccmp
->tx_pn
, ccmp
->rx_pn
,
423 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
424 ccmp
->dot11RSNAStatsCCMPReplays
,
425 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
430 static struct lib80211_crypto_ops rtllib_crypt_ccmp
= {
432 .init
= rtllib_ccmp_init
,
433 .deinit
= rtllib_ccmp_deinit
,
434 .encrypt_mpdu
= rtllib_ccmp_encrypt
,
435 .decrypt_mpdu
= rtllib_ccmp_decrypt
,
436 .encrypt_msdu
= NULL
,
437 .decrypt_msdu
= NULL
,
438 .set_key
= rtllib_ccmp_set_key
,
439 .get_key
= rtllib_ccmp_get_key
,
440 .print_stats
= rtllib_ccmp_print_stats
,
441 .extra_mpdu_prefix_len
= CCMP_HDR_LEN
,
442 .extra_mpdu_postfix_len
= CCMP_MIC_LEN
,
443 .owner
= THIS_MODULE
,
447 int __init
rtllib_crypto_ccmp_init(void)
449 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp
);
453 void __exit
rtllib_crypto_ccmp_exit(void)
455 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp
);
458 module_init(rtllib_crypto_ccmp_init
);
459 module_exit(rtllib_crypto_ccmp_exit
);
461 MODULE_LICENSE("GPL");