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/config.h>
13 #include <linux/version.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_tfm
*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 void ieee80211_ccmp_aes_encrypt(struct crypto_tfm
*tfm
,
62 const u8 pt
[16], u8 ct
[16])
64 struct scatterlist src
, dst
;
66 src
.page
= virt_to_page(pt
);
67 src
.offset
= offset_in_page(pt
);
68 src
.length
= AES_BLOCK_LEN
;
70 dst
.page
= virt_to_page(ct
);
71 dst
.offset
= offset_in_page(ct
);
72 dst
.length
= AES_BLOCK_LEN
;
74 crypto_cipher_encrypt(tfm
, &dst
, &src
, AES_BLOCK_LEN
);
77 static void *ieee80211_ccmp_init(int key_idx
)
79 struct ieee80211_ccmp_data
*priv
;
81 priv
= kmalloc(sizeof(*priv
), GFP_ATOMIC
);
84 memset(priv
, 0, sizeof(*priv
));
85 priv
->key_idx
= key_idx
;
87 priv
->tfm
= crypto_alloc_tfm("aes", 0);
88 if (priv
->tfm
== NULL
) {
89 printk(KERN_DEBUG
"ieee80211_crypt_ccmp: could not allocate "
99 crypto_free_tfm(priv
->tfm
);
106 static void ieee80211_ccmp_deinit(void *priv
)
108 struct ieee80211_ccmp_data
*_priv
= priv
;
109 if (_priv
&& _priv
->tfm
)
110 crypto_free_tfm(_priv
->tfm
);
114 static inline void xor_block(u8
* b
, u8
* a
, size_t len
)
117 for (i
= 0; i
< len
; i
++)
121 static void ccmp_init_blocks(struct crypto_tfm
*tfm
,
122 struct ieee80211_hdr
*hdr
,
123 u8
* pn
, size_t dlen
, u8
* b0
, u8
* auth
, u8
* s0
)
128 int a4_included
, qc_included
;
129 u8 aad
[2 * AES_BLOCK_LEN
];
131 fc
= le16_to_cpu(hdr
->frame_ctl
);
132 a4_included
= ((fc
& (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
)) ==
133 (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
));
134 qc_included
= ((WLAN_FC_GET_TYPE(fc
) == IEEE80211_FTYPE_DATA
) &&
135 (WLAN_FC_GET_STYPE(fc
) & 0x08));
140 pos
= (u8
*) & hdr
->addr4
;
147 /* CCM Initial Block:
148 * Flag (Include authentication header, M=3 (8-octet MIC),
149 * L=1 (2-octet Dlen))
150 * Nonce: 0x00 | A2 | PN
154 memcpy(b0
+ 2, hdr
->addr2
, ETH_ALEN
);
155 memcpy(b0
+ 8, pn
, CCMP_PN_LEN
);
156 b0
[14] = (dlen
>> 8) & 0xff;
157 b0
[15] = dlen
& 0xff;
160 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
162 * SC with bits 4..15 (seq#) masked to zero
167 aad
[0] = 0; /* aad_len >> 8 */
168 aad
[1] = aad_len
& 0xff;
169 aad
[2] = pos
[0] & 0x8f;
170 aad
[3] = pos
[1] & 0xc7;
171 memcpy(aad
+ 4, hdr
->addr1
, 3 * ETH_ALEN
);
172 pos
= (u8
*) & hdr
->seq_ctl
;
173 aad
[22] = pos
[0] & 0x0f;
174 aad
[23] = 0; /* all bits masked */
175 memset(aad
+ 24, 0, 8);
177 memcpy(aad
+ 24, hdr
->addr4
, ETH_ALEN
);
179 aad
[a4_included
? 30 : 24] = qc
;
180 /* rest of QC masked */
183 /* Start with the first block and AAD */
184 ieee80211_ccmp_aes_encrypt(tfm
, b0
, auth
);
185 xor_block(auth
, aad
, AES_BLOCK_LEN
);
186 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
187 xor_block(auth
, &aad
[AES_BLOCK_LEN
], AES_BLOCK_LEN
);
188 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
191 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
;
197 int data_len
, i
, blocks
, last
, len
;
199 struct ieee80211_hdr
*hdr
;
205 if (skb_headroom(skb
) < CCMP_HDR_LEN
||
206 skb_tailroom(skb
) < CCMP_MIC_LEN
|| skb
->len
< hdr_len
)
209 data_len
= skb
->len
- hdr_len
;
210 pos
= skb_push(skb
, CCMP_HDR_LEN
);
211 memmove(pos
, pos
+ CCMP_HDR_LEN
, hdr_len
);
213 mic
= skb_put(skb
, CCMP_MIC_LEN
);
218 if (key
->tx_pn
[i
] != 0)
223 *pos
++ = key
->tx_pn
[5];
224 *pos
++ = key
->tx_pn
[4];
226 *pos
++ = (key
->key_idx
<< 6) | (1 << 5) /* Ext IV included */ ;
227 *pos
++ = key
->tx_pn
[3];
228 *pos
++ = key
->tx_pn
[2];
229 *pos
++ = key
->tx_pn
[1];
230 *pos
++ = key
->tx_pn
[0];
232 hdr
= (struct ieee80211_hdr
*)skb
->data
;
233 ccmp_init_blocks(key
->tfm
, hdr
, key
->tx_pn
, data_len
, b0
, b
, s0
);
235 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
236 last
= data_len
% AES_BLOCK_LEN
;
238 for (i
= 1; i
<= blocks
; i
++) {
239 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
241 xor_block(b
, pos
, len
);
242 ieee80211_ccmp_aes_encrypt(key
->tfm
, b
, b
);
243 /* Encryption, with counter */
244 b0
[14] = (i
>> 8) & 0xff;
246 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, e
);
247 xor_block(pos
, e
, len
);
251 for (i
= 0; i
< CCMP_MIC_LEN
; i
++)
252 mic
[i
] = b
[i
] ^ s0
[i
];
257 static int ieee80211_ccmp_decrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
259 struct ieee80211_ccmp_data
*key
= priv
;
261 struct ieee80211_hdr
*hdr
;
266 int i
, blocks
, last
, len
;
267 size_t data_len
= skb
->len
- hdr_len
- CCMP_HDR_LEN
- CCMP_MIC_LEN
;
268 u8
*mic
= skb
->data
+ skb
->len
- CCMP_MIC_LEN
;
270 if (skb
->len
< hdr_len
+ CCMP_HDR_LEN
+ CCMP_MIC_LEN
) {
271 key
->dot11RSNAStatsCCMPFormatErrors
++;
275 hdr
= (struct ieee80211_hdr
*)skb
->data
;
276 pos
= skb
->data
+ hdr_len
;
278 if (!(keyidx
& (1 << 5))) {
279 if (net_ratelimit()) {
280 printk(KERN_DEBUG
"CCMP: received packet without ExtIV"
281 " flag from " MAC_FMT
"\n", MAC_ARG(hdr
->addr2
));
283 key
->dot11RSNAStatsCCMPFormatErrors
++;
287 if (key
->key_idx
!= keyidx
) {
288 printk(KERN_DEBUG
"CCMP: RX tkey->key_idx=%d frame "
289 "keyidx=%d priv=%p\n", key
->key_idx
, keyidx
, priv
);
293 if (net_ratelimit()) {
294 printk(KERN_DEBUG
"CCMP: received packet from " MAC_FMT
295 " with keyid=%d that does not have a configured"
296 " key\n", MAC_ARG(hdr
->addr2
), keyidx
);
309 if (memcmp(pn
, key
->rx_pn
, CCMP_PN_LEN
) <= 0) {
310 if (net_ratelimit()) {
311 printk(KERN_DEBUG
"CCMP: replay detected: STA=" MAC_FMT
312 " previous PN %02x%02x%02x%02x%02x%02x "
313 "received PN %02x%02x%02x%02x%02x%02x\n",
314 MAC_ARG(hdr
->addr2
), MAC_ARG(key
->rx_pn
),
317 key
->dot11RSNAStatsCCMPReplays
++;
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 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, b
);
333 xor_block(pos
, b
, len
);
335 xor_block(a
, pos
, len
);
336 ieee80211_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 MAC_FMT
"\n", MAC_ARG(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
);
359 static int ieee80211_ccmp_set_key(void *key
, int len
, u8
* seq
, void *priv
)
361 struct ieee80211_ccmp_data
*data
= priv
;
363 struct crypto_tfm
*tfm
= data
->tfm
;
365 keyidx
= data
->key_idx
;
366 memset(data
, 0, sizeof(*data
));
367 data
->key_idx
= keyidx
;
369 if (len
== CCMP_TK_LEN
) {
370 memcpy(data
->key
, key
, CCMP_TK_LEN
);
373 data
->rx_pn
[0] = seq
[5];
374 data
->rx_pn
[1] = seq
[4];
375 data
->rx_pn
[2] = seq
[3];
376 data
->rx_pn
[3] = seq
[2];
377 data
->rx_pn
[4] = seq
[1];
378 data
->rx_pn
[5] = seq
[0];
380 crypto_cipher_setkey(data
->tfm
, data
->key
, CCMP_TK_LEN
);
389 static int ieee80211_ccmp_get_key(void *key
, int len
, u8
* seq
, void *priv
)
391 struct ieee80211_ccmp_data
*data
= priv
;
393 if (len
< CCMP_TK_LEN
)
398 memcpy(key
, data
->key
, CCMP_TK_LEN
);
401 seq
[0] = data
->tx_pn
[5];
402 seq
[1] = data
->tx_pn
[4];
403 seq
[2] = data
->tx_pn
[3];
404 seq
[3] = data
->tx_pn
[2];
405 seq
[4] = data
->tx_pn
[1];
406 seq
[5] = data
->tx_pn
[0];
412 static char *ieee80211_ccmp_print_stats(char *p
, void *priv
)
414 struct ieee80211_ccmp_data
*ccmp
= priv
;
415 p
+= sprintf(p
, "key[%d] alg=CCMP key_set=%d "
416 "tx_pn=%02x%02x%02x%02x%02x%02x "
417 "rx_pn=%02x%02x%02x%02x%02x%02x "
418 "format_errors=%d replays=%d decrypt_errors=%d\n",
419 ccmp
->key_idx
, ccmp
->key_set
,
420 MAC_ARG(ccmp
->tx_pn
), MAC_ARG(ccmp
->rx_pn
),
421 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
422 ccmp
->dot11RSNAStatsCCMPReplays
,
423 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
428 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp
= {
430 .init
= ieee80211_ccmp_init
,
431 .deinit
= ieee80211_ccmp_deinit
,
432 .encrypt_mpdu
= ieee80211_ccmp_encrypt
,
433 .decrypt_mpdu
= ieee80211_ccmp_decrypt
,
434 .encrypt_msdu
= NULL
,
435 .decrypt_msdu
= NULL
,
436 .set_key
= ieee80211_ccmp_set_key
,
437 .get_key
= ieee80211_ccmp_get_key
,
438 .print_stats
= ieee80211_ccmp_print_stats
,
439 .extra_prefix_len
= CCMP_HDR_LEN
,
440 .extra_postfix_len
= CCMP_MIC_LEN
,
441 .owner
= THIS_MODULE
,
444 static int __init
ieee80211_crypto_ccmp_init(void)
446 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp
);
449 static void __exit
ieee80211_crypto_ccmp_exit(void)
451 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp
);
454 module_init(ieee80211_crypto_ccmp_init
);
455 module_exit(ieee80211_crypto_ccmp_exit
);