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>
29 MODULE_AUTHOR("Jouni Malinen");
30 MODULE_DESCRIPTION("Host AP crypt: CCMP");
31 MODULE_LICENSE("GPL");
33 #define AES_BLOCK_LEN 16
34 #define CCMP_HDR_LEN 8
35 #define CCMP_MIC_LEN 8
36 #define CCMP_TK_LEN 16
39 struct ieee80211_ccmp_data
{
43 u8 tx_pn
[CCMP_PN_LEN
];
44 u8 rx_pn
[CCMP_PN_LEN
];
46 u32 dot11RSNAStatsCCMPFormatErrors
;
47 u32 dot11RSNAStatsCCMPReplays
;
48 u32 dot11RSNAStatsCCMPDecryptErrors
;
52 struct crypto_cipher
*tfm
;
54 /* scratch buffers for virt_to_page() (crypto API) */
55 u8 tx_b0
[AES_BLOCK_LEN
], tx_b
[AES_BLOCK_LEN
],
56 tx_e
[AES_BLOCK_LEN
], tx_s0
[AES_BLOCK_LEN
];
57 u8 rx_b0
[AES_BLOCK_LEN
], rx_b
[AES_BLOCK_LEN
], rx_a
[AES_BLOCK_LEN
];
60 static inline void ieee80211_ccmp_aes_encrypt(struct crypto_cipher
*tfm
,
61 const u8 pt
[16], u8 ct
[16])
63 crypto_cipher_encrypt_one(tfm
, ct
, pt
);
66 static void *ieee80211_ccmp_init(int key_idx
)
68 struct ieee80211_ccmp_data
*priv
;
70 priv
= kzalloc(sizeof(*priv
), GFP_ATOMIC
);
73 priv
->key_idx
= key_idx
;
75 priv
->tfm
= crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC
);
76 if (IS_ERR(priv
->tfm
)) {
77 printk(KERN_DEBUG
"ieee80211_crypt_ccmp: could not allocate "
88 crypto_free_cipher(priv
->tfm
);
95 static void ieee80211_ccmp_deinit(void *priv
)
97 struct ieee80211_ccmp_data
*_priv
= priv
;
98 if (_priv
&& _priv
->tfm
)
99 crypto_free_cipher(_priv
->tfm
);
103 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_cipher
*tfm
,
111 struct ieee80211_hdr_4addr
*hdr
,
112 u8
* pn
, size_t dlen
, u8
* b0
, u8
* auth
, u8
* s0
)
117 int a4_included
, qc_included
;
118 u8 aad
[2 * AES_BLOCK_LEN
];
120 fc
= le16_to_cpu(hdr
->frame_ctl
);
121 a4_included
= ((fc
& (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
)) ==
122 (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
));
123 qc_included
= ((WLAN_FC_GET_TYPE(fc
) == IEEE80211_FTYPE_DATA
) &&
124 (WLAN_FC_GET_STYPE(fc
) & IEEE80211_STYPE_QOS_DATA
));
129 pos
= (u8
*) & hdr
->addr4
;
136 /* CCM Initial Block:
137 * Flag (Include authentication header, M=3 (8-octet MIC),
138 * L=1 (2-octet Dlen))
139 * Nonce: 0x00 | A2 | PN
143 memcpy(b0
+ 2, hdr
->addr2
, ETH_ALEN
);
144 memcpy(b0
+ 8, pn
, CCMP_PN_LEN
);
145 b0
[14] = (dlen
>> 8) & 0xff;
146 b0
[15] = dlen
& 0xff;
149 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
151 * SC with bits 4..15 (seq#) masked to zero
156 aad
[0] = 0; /* aad_len >> 8 */
157 aad
[1] = aad_len
& 0xff;
158 aad
[2] = pos
[0] & 0x8f;
159 aad
[3] = pos
[1] & 0xc7;
160 memcpy(aad
+ 4, hdr
->addr1
, 3 * ETH_ALEN
);
161 pos
= (u8
*) & hdr
->seq_ctl
;
162 aad
[22] = pos
[0] & 0x0f;
163 aad
[23] = 0; /* all bits masked */
164 memset(aad
+ 24, 0, 8);
166 memcpy(aad
+ 24, hdr
->addr4
, ETH_ALEN
);
168 aad
[a4_included
? 30 : 24] = qc
;
169 /* rest of QC masked */
172 /* Start with the first block and AAD */
173 ieee80211_ccmp_aes_encrypt(tfm
, b0
, auth
);
174 xor_block(auth
, aad
, AES_BLOCK_LEN
);
175 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
176 xor_block(auth
, &aad
[AES_BLOCK_LEN
], AES_BLOCK_LEN
);
177 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
180 ieee80211_ccmp_aes_encrypt(tfm
, b0
, s0
);
183 static int ieee80211_ccmp_hdr(struct sk_buff
*skb
, int hdr_len
,
184 u8
*aeskey
, int keylen
, void *priv
)
186 struct ieee80211_ccmp_data
*key
= priv
;
190 if (skb_headroom(skb
) < CCMP_HDR_LEN
|| skb
->len
< hdr_len
)
193 if (aeskey
!= NULL
&& keylen
>= CCMP_TK_LEN
)
194 memcpy(aeskey
, key
->key
, CCMP_TK_LEN
);
196 pos
= skb_push(skb
, CCMP_HDR_LEN
);
197 memmove(pos
, pos
+ CCMP_HDR_LEN
, hdr_len
);
203 if (key
->tx_pn
[i
] != 0)
208 *pos
++ = key
->tx_pn
[5];
209 *pos
++ = key
->tx_pn
[4];
211 *pos
++ = (key
->key_idx
<< 6) | (1 << 5) /* Ext IV included */ ;
212 *pos
++ = key
->tx_pn
[3];
213 *pos
++ = key
->tx_pn
[2];
214 *pos
++ = key
->tx_pn
[1];
215 *pos
++ = key
->tx_pn
[0];
220 static int ieee80211_ccmp_encrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
222 struct ieee80211_ccmp_data
*key
= priv
;
223 int data_len
, i
, blocks
, last
, len
;
225 struct ieee80211_hdr_4addr
*hdr
;
231 if (skb_tailroom(skb
) < CCMP_MIC_LEN
|| skb
->len
< hdr_len
)
234 data_len
= skb
->len
- hdr_len
;
235 len
= ieee80211_ccmp_hdr(skb
, hdr_len
, NULL
, 0, priv
);
239 pos
= skb
->data
+ hdr_len
+ CCMP_HDR_LEN
;
240 mic
= skb_put(skb
, CCMP_MIC_LEN
);
241 hdr
= (struct ieee80211_hdr_4addr
*)skb
->data
;
242 ccmp_init_blocks(key
->tfm
, hdr
, key
->tx_pn
, data_len
, b0
, b
, s0
);
244 blocks
= DIV_ROUND_UP(data_len
, AES_BLOCK_LEN
);
245 last
= data_len
% AES_BLOCK_LEN
;
247 for (i
= 1; i
<= blocks
; i
++) {
248 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
250 xor_block(b
, pos
, len
);
251 ieee80211_ccmp_aes_encrypt(key
->tfm
, b
, b
);
252 /* Encryption, with counter */
253 b0
[14] = (i
>> 8) & 0xff;
255 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, e
);
256 xor_block(pos
, e
, len
);
260 for (i
= 0; i
< CCMP_MIC_LEN
; i
++)
261 mic
[i
] = b
[i
] ^ s0
[i
];
267 * deal with seq counter wrapping correctly.
268 * refer to timer_after() for jiffies wrapping handling
270 static inline int ccmp_replay_check(u8
*pn_n
, u8
*pn_o
)
275 iv32_n
= (pn_n
[0] << 24) | (pn_n
[1] << 16) | (pn_n
[2] << 8) | pn_n
[3];
276 iv16_n
= (pn_n
[4] << 8) | pn_n
[5];
278 iv32_o
= (pn_o
[0] << 24) | (pn_o
[1] << 16) | (pn_o
[2] << 8) | pn_o
[3];
279 iv16_o
= (pn_o
[4] << 8) | pn_o
[5];
281 if ((s32
)iv32_n
- (s32
)iv32_o
< 0 ||
282 (iv32_n
== iv32_o
&& iv16_n
<= iv16_o
))
287 static int ieee80211_ccmp_decrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
289 struct ieee80211_ccmp_data
*key
= priv
;
291 struct ieee80211_hdr_4addr
*hdr
;
296 int i
, blocks
, last
, len
;
297 size_t data_len
= skb
->len
- hdr_len
- CCMP_HDR_LEN
- CCMP_MIC_LEN
;
298 u8
*mic
= skb
->data
+ skb
->len
- CCMP_MIC_LEN
;
299 DECLARE_MAC_BUF(mac
);
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 %s\n", print_mac(mac
, 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 %s"
326 " with keyid=%d that does not have a configured"
327 " key\n", print_mac(mac
, hdr
->addr2
), keyidx
);
340 if (ccmp_replay_check(pn
, key
->rx_pn
)) {
341 if (net_ratelimit()) {
342 IEEE80211_DEBUG_DROP("CCMP: replay detected: STA=%s "
343 "previous PN %02x%02x%02x%02x%02x%02x "
344 "received PN %02x%02x%02x%02x%02x%02x\n",
345 print_mac(mac
, hdr
->addr2
),
346 key
->rx_pn
[0], key
->rx_pn
[1], key
->rx_pn
[2],
347 key
->rx_pn
[3], key
->rx_pn
[4], key
->rx_pn
[5],
348 pn
[0], pn
[1], pn
[2], pn
[3], pn
[4], pn
[5]);
350 key
->dot11RSNAStatsCCMPReplays
++;
354 ccmp_init_blocks(key
->tfm
, hdr
, pn
, data_len
, b0
, a
, b
);
355 xor_block(mic
, b
, CCMP_MIC_LEN
);
357 blocks
= DIV_ROUND_UP(data_len
, AES_BLOCK_LEN
);
358 last
= data_len
% AES_BLOCK_LEN
;
360 for (i
= 1; i
<= blocks
; i
++) {
361 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
362 /* Decrypt, with counter */
363 b0
[14] = (i
>> 8) & 0xff;
365 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, b
);
366 xor_block(pos
, b
, len
);
368 xor_block(a
, pos
, len
);
369 ieee80211_ccmp_aes_encrypt(key
->tfm
, a
, a
);
373 if (memcmp(mic
, a
, CCMP_MIC_LEN
) != 0) {
374 if (net_ratelimit()) {
375 printk(KERN_DEBUG
"CCMP: decrypt failed: STA="
376 "%s\n", print_mac(mac
, hdr
->addr2
));
378 key
->dot11RSNAStatsCCMPDecryptErrors
++;
382 memcpy(key
->rx_pn
, pn
, CCMP_PN_LEN
);
384 /* Remove hdr and MIC */
385 memmove(skb
->data
+ CCMP_HDR_LEN
, skb
->data
, hdr_len
);
386 skb_pull(skb
, CCMP_HDR_LEN
);
387 skb_trim(skb
, skb
->len
- CCMP_MIC_LEN
);
392 static int ieee80211_ccmp_set_key(void *key
, int len
, u8
* seq
, void *priv
)
394 struct ieee80211_ccmp_data
*data
= priv
;
396 struct crypto_cipher
*tfm
= data
->tfm
;
398 keyidx
= data
->key_idx
;
399 memset(data
, 0, sizeof(*data
));
400 data
->key_idx
= keyidx
;
402 if (len
== CCMP_TK_LEN
) {
403 memcpy(data
->key
, key
, CCMP_TK_LEN
);
406 data
->rx_pn
[0] = seq
[5];
407 data
->rx_pn
[1] = seq
[4];
408 data
->rx_pn
[2] = seq
[3];
409 data
->rx_pn
[3] = seq
[2];
410 data
->rx_pn
[4] = seq
[1];
411 data
->rx_pn
[5] = seq
[0];
413 crypto_cipher_setkey(data
->tfm
, data
->key
, CCMP_TK_LEN
);
422 static int ieee80211_ccmp_get_key(void *key
, int len
, u8
* seq
, void *priv
)
424 struct ieee80211_ccmp_data
*data
= priv
;
426 if (len
< CCMP_TK_LEN
)
431 memcpy(key
, data
->key
, CCMP_TK_LEN
);
434 seq
[0] = data
->tx_pn
[5];
435 seq
[1] = data
->tx_pn
[4];
436 seq
[2] = data
->tx_pn
[3];
437 seq
[3] = data
->tx_pn
[2];
438 seq
[4] = data
->tx_pn
[1];
439 seq
[5] = data
->tx_pn
[0];
445 static char *ieee80211_ccmp_print_stats(char *p
, void *priv
)
447 struct ieee80211_ccmp_data
*ccmp
= priv
;
449 p
+= sprintf(p
, "key[%d] alg=CCMP key_set=%d "
450 "tx_pn=%02x%02x%02x%02x%02x%02x "
451 "rx_pn=%02x%02x%02x%02x%02x%02x "
452 "format_errors=%d replays=%d decrypt_errors=%d\n",
453 ccmp
->key_idx
, ccmp
->key_set
,
454 ccmp
->tx_pn
[0], ccmp
->tx_pn
[1], ccmp
->tx_pn
[2],
455 ccmp
->tx_pn
[3], ccmp
->tx_pn
[4], ccmp
->tx_pn
[5],
456 ccmp
->rx_pn
[0], ccmp
->rx_pn
[1], ccmp
->rx_pn
[2],
457 ccmp
->rx_pn
[3], ccmp
->rx_pn
[4], ccmp
->rx_pn
[5],
458 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
459 ccmp
->dot11RSNAStatsCCMPReplays
,
460 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
465 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp
= {
467 .init
= ieee80211_ccmp_init
,
468 .deinit
= ieee80211_ccmp_deinit
,
469 .build_iv
= ieee80211_ccmp_hdr
,
470 .encrypt_mpdu
= ieee80211_ccmp_encrypt
,
471 .decrypt_mpdu
= ieee80211_ccmp_decrypt
,
472 .encrypt_msdu
= NULL
,
473 .decrypt_msdu
= NULL
,
474 .set_key
= ieee80211_ccmp_set_key
,
475 .get_key
= ieee80211_ccmp_get_key
,
476 .print_stats
= ieee80211_ccmp_print_stats
,
477 .extra_mpdu_prefix_len
= CCMP_HDR_LEN
,
478 .extra_mpdu_postfix_len
= CCMP_MIC_LEN
,
479 .owner
= THIS_MODULE
,
482 static int __init
ieee80211_crypto_ccmp_init(void)
484 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp
);
487 static void __exit
ieee80211_crypto_ccmp_exit(void)
489 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp
);
492 module_init(ieee80211_crypto_ccmp_init
);
493 module_exit(ieee80211_crypto_ccmp_exit
);