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 <asm/string.h>
21 #include <linux/wireless.h>
23 #include <net/ieee80211.h>
25 #include <linux/crypto.h>
26 #include <asm/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 struct scatterlist src
, dst
;
64 src
.page
= virt_to_page(pt
);
65 src
.offset
= offset_in_page(pt
);
66 src
.length
= AES_BLOCK_LEN
;
68 dst
.page
= virt_to_page(ct
);
69 dst
.offset
= offset_in_page(ct
);
70 dst
.length
= AES_BLOCK_LEN
;
72 crypto_cipher_encrypt(tfm
, &dst
, &src
, AES_BLOCK_LEN
);
75 static void *ieee80211_ccmp_init(int key_idx
)
77 struct ieee80211_ccmp_data
*priv
;
79 priv
= kzalloc(sizeof(*priv
), GFP_ATOMIC
);
82 priv
->key_idx
= key_idx
;
84 priv
->tfm
= crypto_alloc_tfm("aes", 0);
85 if (priv
->tfm
== NULL
) {
86 printk(KERN_DEBUG
"ieee80211_crypt_ccmp: could not allocate "
96 crypto_free_tfm(priv
->tfm
);
103 static void ieee80211_ccmp_deinit(void *priv
)
105 struct ieee80211_ccmp_data
*_priv
= priv
;
106 if (_priv
&& _priv
->tfm
)
107 crypto_free_tfm(_priv
->tfm
);
111 static inline void xor_block(u8
* b
, u8
* a
, size_t len
)
114 for (i
= 0; i
< len
; i
++)
118 static void ccmp_init_blocks(struct crypto_tfm
*tfm
,
119 struct ieee80211_hdr_4addr
*hdr
,
120 u8
* pn
, size_t dlen
, u8
* b0
, u8
* auth
, u8
* s0
)
125 int a4_included
, qc_included
;
126 u8 aad
[2 * AES_BLOCK_LEN
];
128 fc
= le16_to_cpu(hdr
->frame_ctl
);
129 a4_included
= ((fc
& (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
)) ==
130 (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
));
131 qc_included
= ((WLAN_FC_GET_TYPE(fc
) == IEEE80211_FTYPE_DATA
) &&
132 (WLAN_FC_GET_STYPE(fc
) & IEEE80211_STYPE_QOS_DATA
));
137 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
151 memcpy(b0
+ 2, hdr
->addr2
, ETH_ALEN
);
152 memcpy(b0
+ 8, pn
, CCMP_PN_LEN
);
153 b0
[14] = (dlen
>> 8) & 0xff;
154 b0
[15] = dlen
& 0xff;
157 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
159 * SC with bits 4..15 (seq#) masked to zero
164 aad
[0] = 0; /* aad_len >> 8 */
165 aad
[1] = aad_len
& 0xff;
166 aad
[2] = pos
[0] & 0x8f;
167 aad
[3] = pos
[1] & 0xc7;
168 memcpy(aad
+ 4, hdr
->addr1
, 3 * ETH_ALEN
);
169 pos
= (u8
*) & hdr
->seq_ctl
;
170 aad
[22] = pos
[0] & 0x0f;
171 aad
[23] = 0; /* all bits masked */
172 memset(aad
+ 24, 0, 8);
174 memcpy(aad
+ 24, hdr
->addr4
, ETH_ALEN
);
176 aad
[a4_included
? 30 : 24] = qc
;
177 /* rest of QC masked */
180 /* Start with the first block and AAD */
181 ieee80211_ccmp_aes_encrypt(tfm
, b0
, auth
);
182 xor_block(auth
, aad
, AES_BLOCK_LEN
);
183 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
184 xor_block(auth
, &aad
[AES_BLOCK_LEN
], AES_BLOCK_LEN
);
185 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
188 ieee80211_ccmp_aes_encrypt(tfm
, b0
, s0
);
191 static int ieee80211_ccmp_hdr(struct sk_buff
*skb
, int hdr_len
,
192 u8
*aeskey
, int keylen
, void *priv
)
194 struct ieee80211_ccmp_data
*key
= priv
;
198 if (skb_headroom(skb
) < CCMP_HDR_LEN
|| skb
->len
< hdr_len
)
201 if (aeskey
!= NULL
&& keylen
>= CCMP_TK_LEN
)
202 memcpy(aeskey
, key
->key
, CCMP_TK_LEN
);
204 pos
= skb_push(skb
, CCMP_HDR_LEN
);
205 memmove(pos
, pos
+ CCMP_HDR_LEN
, hdr_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];
228 static int ieee80211_ccmp_encrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
230 struct ieee80211_ccmp_data
*key
= priv
;
231 int data_len
, i
, blocks
, last
, len
;
233 struct ieee80211_hdr_4addr
*hdr
;
239 if (skb_tailroom(skb
) < CCMP_MIC_LEN
|| skb
->len
< hdr_len
)
242 data_len
= skb
->len
- hdr_len
;
243 len
= ieee80211_ccmp_hdr(skb
, hdr_len
, NULL
, 0, priv
);
247 pos
= skb
->data
+ hdr_len
+ CCMP_HDR_LEN
;
248 mic
= skb_put(skb
, CCMP_MIC_LEN
);
249 hdr
= (struct ieee80211_hdr_4addr
*)skb
->data
;
250 ccmp_init_blocks(key
->tfm
, hdr
, key
->tx_pn
, data_len
, b0
, b
, s0
);
252 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
253 last
= data_len
% AES_BLOCK_LEN
;
255 for (i
= 1; i
<= blocks
; i
++) {
256 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
258 xor_block(b
, pos
, len
);
259 ieee80211_ccmp_aes_encrypt(key
->tfm
, b
, b
);
260 /* Encryption, with counter */
261 b0
[14] = (i
>> 8) & 0xff;
263 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, e
);
264 xor_block(pos
, e
, len
);
268 for (i
= 0; i
< CCMP_MIC_LEN
; i
++)
269 mic
[i
] = b
[i
] ^ s0
[i
];
275 * deal with seq counter wrapping correctly.
276 * refer to timer_after() for jiffies wrapping handling
278 static inline int ccmp_replay_check(u8
*pn_n
, u8
*pn_o
)
283 iv32_n
= (pn_n
[0] << 24) | (pn_n
[1] << 16) | (pn_n
[2] << 8) | pn_n
[3];
284 iv16_n
= (pn_n
[4] << 8) | pn_n
[5];
286 iv32_o
= (pn_o
[0] << 24) | (pn_o
[1] << 16) | (pn_o
[2] << 8) | pn_o
[3];
287 iv16_o
= (pn_o
[4] << 8) | pn_o
[5];
289 if ((s32
)iv32_n
- (s32
)iv32_o
< 0 ||
290 (iv32_n
== iv32_o
&& iv16_n
<= iv16_o
))
295 static int ieee80211_ccmp_decrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
297 struct ieee80211_ccmp_data
*key
= priv
;
299 struct ieee80211_hdr_4addr
*hdr
;
304 int i
, blocks
, last
, len
;
305 size_t data_len
= skb
->len
- hdr_len
- CCMP_HDR_LEN
- CCMP_MIC_LEN
;
306 u8
*mic
= skb
->data
+ skb
->len
- CCMP_MIC_LEN
;
308 if (skb
->len
< hdr_len
+ CCMP_HDR_LEN
+ CCMP_MIC_LEN
) {
309 key
->dot11RSNAStatsCCMPFormatErrors
++;
313 hdr
= (struct ieee80211_hdr_4addr
*)skb
->data
;
314 pos
= skb
->data
+ hdr_len
;
316 if (!(keyidx
& (1 << 5))) {
317 if (net_ratelimit()) {
318 printk(KERN_DEBUG
"CCMP: received packet without ExtIV"
319 " flag from " MAC_FMT
"\n", MAC_ARG(hdr
->addr2
));
321 key
->dot11RSNAStatsCCMPFormatErrors
++;
325 if (key
->key_idx
!= keyidx
) {
326 printk(KERN_DEBUG
"CCMP: RX tkey->key_idx=%d frame "
327 "keyidx=%d priv=%p\n", key
->key_idx
, keyidx
, priv
);
331 if (net_ratelimit()) {
332 printk(KERN_DEBUG
"CCMP: received packet from " MAC_FMT
333 " with keyid=%d that does not have a configured"
334 " key\n", MAC_ARG(hdr
->addr2
), keyidx
);
347 if (ccmp_replay_check(pn
, key
->rx_pn
)) {
348 if (net_ratelimit()) {
349 printk(KERN_DEBUG
"CCMP: replay detected: STA=" MAC_FMT
350 " previous PN %02x%02x%02x%02x%02x%02x "
351 "received PN %02x%02x%02x%02x%02x%02x\n",
352 MAC_ARG(hdr
->addr2
), MAC_ARG(key
->rx_pn
),
355 key
->dot11RSNAStatsCCMPReplays
++;
359 ccmp_init_blocks(key
->tfm
, hdr
, pn
, data_len
, b0
, a
, b
);
360 xor_block(mic
, b
, CCMP_MIC_LEN
);
362 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
363 last
= data_len
% AES_BLOCK_LEN
;
365 for (i
= 1; i
<= blocks
; i
++) {
366 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
367 /* Decrypt, with counter */
368 b0
[14] = (i
>> 8) & 0xff;
370 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, b
);
371 xor_block(pos
, b
, len
);
373 xor_block(a
, pos
, len
);
374 ieee80211_ccmp_aes_encrypt(key
->tfm
, a
, a
);
378 if (memcmp(mic
, a
, CCMP_MIC_LEN
) != 0) {
379 if (net_ratelimit()) {
380 printk(KERN_DEBUG
"CCMP: decrypt failed: STA="
381 MAC_FMT
"\n", MAC_ARG(hdr
->addr2
));
383 key
->dot11RSNAStatsCCMPDecryptErrors
++;
387 memcpy(key
->rx_pn
, pn
, CCMP_PN_LEN
);
389 /* Remove hdr and MIC */
390 memmove(skb
->data
+ CCMP_HDR_LEN
, skb
->data
, hdr_len
);
391 skb_pull(skb
, CCMP_HDR_LEN
);
392 skb_trim(skb
, skb
->len
- CCMP_MIC_LEN
);
397 static int ieee80211_ccmp_set_key(void *key
, int len
, u8
* seq
, void *priv
)
399 struct ieee80211_ccmp_data
*data
= priv
;
401 struct crypto_tfm
*tfm
= data
->tfm
;
403 keyidx
= data
->key_idx
;
404 memset(data
, 0, sizeof(*data
));
405 data
->key_idx
= keyidx
;
407 if (len
== CCMP_TK_LEN
) {
408 memcpy(data
->key
, key
, CCMP_TK_LEN
);
411 data
->rx_pn
[0] = seq
[5];
412 data
->rx_pn
[1] = seq
[4];
413 data
->rx_pn
[2] = seq
[3];
414 data
->rx_pn
[3] = seq
[2];
415 data
->rx_pn
[4] = seq
[1];
416 data
->rx_pn
[5] = seq
[0];
418 crypto_cipher_setkey(data
->tfm
, data
->key
, CCMP_TK_LEN
);
427 static int ieee80211_ccmp_get_key(void *key
, int len
, u8
* seq
, void *priv
)
429 struct ieee80211_ccmp_data
*data
= priv
;
431 if (len
< CCMP_TK_LEN
)
436 memcpy(key
, data
->key
, CCMP_TK_LEN
);
439 seq
[0] = data
->tx_pn
[5];
440 seq
[1] = data
->tx_pn
[4];
441 seq
[2] = data
->tx_pn
[3];
442 seq
[3] = data
->tx_pn
[2];
443 seq
[4] = data
->tx_pn
[1];
444 seq
[5] = data
->tx_pn
[0];
450 static char *ieee80211_ccmp_print_stats(char *p
, void *priv
)
452 struct ieee80211_ccmp_data
*ccmp
= priv
;
453 p
+= sprintf(p
, "key[%d] alg=CCMP key_set=%d "
454 "tx_pn=%02x%02x%02x%02x%02x%02x "
455 "rx_pn=%02x%02x%02x%02x%02x%02x "
456 "format_errors=%d replays=%d decrypt_errors=%d\n",
457 ccmp
->key_idx
, ccmp
->key_set
,
458 MAC_ARG(ccmp
->tx_pn
), MAC_ARG(ccmp
->rx_pn
),
459 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
460 ccmp
->dot11RSNAStatsCCMPReplays
,
461 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
466 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp
= {
468 .init
= ieee80211_ccmp_init
,
469 .deinit
= ieee80211_ccmp_deinit
,
470 .build_iv
= ieee80211_ccmp_hdr
,
471 .encrypt_mpdu
= ieee80211_ccmp_encrypt
,
472 .decrypt_mpdu
= ieee80211_ccmp_decrypt
,
473 .encrypt_msdu
= NULL
,
474 .decrypt_msdu
= NULL
,
475 .set_key
= ieee80211_ccmp_set_key
,
476 .get_key
= ieee80211_ccmp_get_key
,
477 .print_stats
= ieee80211_ccmp_print_stats
,
478 .extra_mpdu_prefix_len
= CCMP_HDR_LEN
,
479 .extra_mpdu_postfix_len
= CCMP_MIC_LEN
,
480 .owner
= THIS_MODULE
,
483 static int __init
ieee80211_crypto_ccmp_init(void)
485 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp
);
488 static void __exit
ieee80211_crypto_ccmp_exit(void)
490 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp
);
493 module_init(ieee80211_crypto_ccmp_init
);
494 module_exit(ieee80211_crypto_ccmp_exit
);