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>
28 #include <linux/crypto.h>
29 #include <asm/scatterlist.h>
31 MODULE_AUTHOR("Jouni Malinen");
32 MODULE_DESCRIPTION("Host AP crypt: CCMP");
33 MODULE_LICENSE("GPL");
35 #define AES_BLOCK_LEN 16
36 #define CCMP_HDR_LEN 8
37 #define CCMP_MIC_LEN 8
38 #define CCMP_TK_LEN 16
41 struct ieee80211_ccmp_data
{
45 u8 tx_pn
[CCMP_PN_LEN
];
46 u8 rx_pn
[CCMP_PN_LEN
];
48 u32 dot11RSNAStatsCCMPFormatErrors
;
49 u32 dot11RSNAStatsCCMPReplays
;
50 u32 dot11RSNAStatsCCMPDecryptErrors
;
54 struct crypto_tfm
*tfm
;
56 /* scratch buffers for virt_to_page() (crypto API) */
57 u8 tx_b0
[AES_BLOCK_LEN
], tx_b
[AES_BLOCK_LEN
],
58 tx_e
[AES_BLOCK_LEN
], tx_s0
[AES_BLOCK_LEN
];
59 u8 rx_b0
[AES_BLOCK_LEN
], rx_b
[AES_BLOCK_LEN
], rx_a
[AES_BLOCK_LEN
];
62 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm
*tfm
,
63 const u8 pt
[16], u8 ct
[16])
65 struct scatterlist src
, dst
;
67 src
.page
= virt_to_page(pt
);
68 src
.offset
= offset_in_page(pt
);
69 src
.length
= AES_BLOCK_LEN
;
71 dst
.page
= virt_to_page(ct
);
72 dst
.offset
= offset_in_page(ct
);
73 dst
.length
= AES_BLOCK_LEN
;
75 crypto_cipher_encrypt(tfm
, &dst
, &src
, AES_BLOCK_LEN
);
78 static void * ieee80211_ccmp_init(int key_idx
)
80 struct ieee80211_ccmp_data
*priv
;
82 priv
= kmalloc(sizeof(*priv
), GFP_ATOMIC
);
85 memset(priv
, 0, sizeof(*priv
));
86 priv
->key_idx
= key_idx
;
88 priv
->tfm
= crypto_alloc_tfm("aes", 0);
89 if (priv
->tfm
== NULL
) {
90 printk(KERN_DEBUG
"ieee80211_crypt_ccmp: could not allocate "
100 crypto_free_tfm(priv
->tfm
);
108 static void ieee80211_ccmp_deinit(void *priv
)
110 struct ieee80211_ccmp_data
*_priv
= priv
;
111 if (_priv
&& _priv
->tfm
)
112 crypto_free_tfm(_priv
->tfm
);
117 static inline void xor_block(u8
*b
, u8
*a
, size_t len
)
120 for (i
= 0; i
< len
; i
++)
125 static void ccmp_init_blocks(struct crypto_tfm
*tfm
,
126 struct ieee80211_hdr
*hdr
,
127 u8
*pn
, size_t dlen
, u8
*b0
, u8
*auth
,
133 int a4_included
, qc_included
;
134 u8 aad
[2 * AES_BLOCK_LEN
];
136 fc
= le16_to_cpu(hdr
->frame_ctl
);
137 a4_included
= ((fc
& (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
)) ==
138 (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
));
139 qc_included
= ((WLAN_FC_GET_TYPE(fc
) == IEEE80211_FTYPE_DATA
) &&
140 (WLAN_FC_GET_STYPE(fc
) & 0x08));
145 pos
= (u8
*) &hdr
->addr4
;
152 /* CCM Initial Block:
153 * Flag (Include authentication header, M=3 (8-octet MIC),
154 * L=1 (2-octet Dlen))
155 * Nonce: 0x00 | A2 | PN
159 memcpy(b0
+ 2, hdr
->addr2
, ETH_ALEN
);
160 memcpy(b0
+ 8, pn
, CCMP_PN_LEN
);
161 b0
[14] = (dlen
>> 8) & 0xff;
162 b0
[15] = dlen
& 0xff;
165 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
167 * SC with bits 4..15 (seq#) masked to zero
172 aad
[0] = 0; /* aad_len >> 8 */
173 aad
[1] = aad_len
& 0xff;
174 aad
[2] = pos
[0] & 0x8f;
175 aad
[3] = pos
[1] & 0xc7;
176 memcpy(aad
+ 4, hdr
->addr1
, 3 * ETH_ALEN
);
177 pos
= (u8
*) &hdr
->seq_ctl
;
178 aad
[22] = pos
[0] & 0x0f;
179 aad
[23] = 0; /* all bits masked */
180 memset(aad
+ 24, 0, 8);
182 memcpy(aad
+ 24, hdr
->addr4
, ETH_ALEN
);
184 aad
[a4_included
? 30 : 24] = qc
;
185 /* rest of QC masked */
188 /* Start with the first block and AAD */
189 ieee80211_ccmp_aes_encrypt(tfm
, b0
, auth
);
190 xor_block(auth
, aad
, AES_BLOCK_LEN
);
191 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
192 xor_block(auth
, &aad
[AES_BLOCK_LEN
], AES_BLOCK_LEN
);
193 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
196 ieee80211_ccmp_aes_encrypt(tfm
, b0
, s0
);
200 static int ieee80211_ccmp_encrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
202 struct ieee80211_ccmp_data
*key
= priv
;
203 int data_len
, i
, blocks
, last
, len
;
205 struct ieee80211_hdr
*hdr
;
211 if (skb_headroom(skb
) < CCMP_HDR_LEN
||
212 skb_tailroom(skb
) < CCMP_MIC_LEN
||
216 data_len
= skb
->len
- hdr_len
;
217 pos
= skb_push(skb
, CCMP_HDR_LEN
);
218 memmove(pos
, pos
+ CCMP_HDR_LEN
, hdr_len
);
220 mic
= skb_put(skb
, CCMP_MIC_LEN
);
225 if (key
->tx_pn
[i
] != 0)
230 *pos
++ = key
->tx_pn
[5];
231 *pos
++ = key
->tx_pn
[4];
233 *pos
++ = (key
->key_idx
<< 6) | (1 << 5) /* Ext IV included */;
234 *pos
++ = key
->tx_pn
[3];
235 *pos
++ = key
->tx_pn
[2];
236 *pos
++ = key
->tx_pn
[1];
237 *pos
++ = key
->tx_pn
[0];
239 hdr
= (struct ieee80211_hdr
*) skb
->data
;
240 ccmp_init_blocks(key
->tfm
, hdr
, key
->tx_pn
, data_len
, b0
, b
, s0
);
242 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
243 last
= data_len
% AES_BLOCK_LEN
;
245 for (i
= 1; i
<= blocks
; i
++) {
246 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
248 xor_block(b
, pos
, len
);
249 ieee80211_ccmp_aes_encrypt(key
->tfm
, b
, b
);
250 /* Encryption, with counter */
251 b0
[14] = (i
>> 8) & 0xff;
253 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, e
);
254 xor_block(pos
, e
, len
);
258 for (i
= 0; i
< CCMP_MIC_LEN
; i
++)
259 mic
[i
] = b
[i
] ^ s0
[i
];
265 static int ieee80211_ccmp_decrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
267 struct ieee80211_ccmp_data
*key
= priv
;
269 struct ieee80211_hdr
*hdr
;
274 int i
, blocks
, last
, len
;
275 size_t data_len
= skb
->len
- hdr_len
- CCMP_HDR_LEN
- CCMP_MIC_LEN
;
276 u8
*mic
= skb
->data
+ skb
->len
- CCMP_MIC_LEN
;
278 if (skb
->len
< hdr_len
+ CCMP_HDR_LEN
+ CCMP_MIC_LEN
) {
279 key
->dot11RSNAStatsCCMPFormatErrors
++;
283 hdr
= (struct ieee80211_hdr
*) skb
->data
;
284 pos
= skb
->data
+ hdr_len
;
286 if (!(keyidx
& (1 << 5))) {
287 if (net_ratelimit()) {
288 printk(KERN_DEBUG
"CCMP: received packet without ExtIV"
289 " flag from " MAC_FMT
"\n", MAC_ARG(hdr
->addr2
));
291 key
->dot11RSNAStatsCCMPFormatErrors
++;
295 if (key
->key_idx
!= keyidx
) {
296 printk(KERN_DEBUG
"CCMP: RX tkey->key_idx=%d frame "
297 "keyidx=%d priv=%p\n", key
->key_idx
, keyidx
, priv
);
301 if (net_ratelimit()) {
302 printk(KERN_DEBUG
"CCMP: received packet from " MAC_FMT
303 " with keyid=%d that does not have a configured"
304 " key\n", MAC_ARG(hdr
->addr2
), keyidx
);
317 if (memcmp(pn
, key
->rx_pn
, CCMP_PN_LEN
) <= 0) {
318 if (net_ratelimit()) {
319 printk(KERN_DEBUG
"CCMP: replay detected: STA=" MAC_FMT
320 " previous PN %02x%02x%02x%02x%02x%02x "
321 "received PN %02x%02x%02x%02x%02x%02x\n",
322 MAC_ARG(hdr
->addr2
), MAC_ARG(key
->rx_pn
),
325 key
->dot11RSNAStatsCCMPReplays
++;
329 ccmp_init_blocks(key
->tfm
, hdr
, pn
, data_len
, b0
, a
, b
);
330 xor_block(mic
, b
, CCMP_MIC_LEN
);
332 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
333 last
= data_len
% AES_BLOCK_LEN
;
335 for (i
= 1; i
<= blocks
; i
++) {
336 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
337 /* Decrypt, with counter */
338 b0
[14] = (i
>> 8) & 0xff;
340 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, b
);
341 xor_block(pos
, b
, len
);
343 xor_block(a
, pos
, len
);
344 ieee80211_ccmp_aes_encrypt(key
->tfm
, a
, a
);
348 if (memcmp(mic
, a
, CCMP_MIC_LEN
) != 0) {
349 if (net_ratelimit()) {
350 printk(KERN_DEBUG
"CCMP: decrypt failed: STA="
351 MAC_FMT
"\n", MAC_ARG(hdr
->addr2
));
353 key
->dot11RSNAStatsCCMPDecryptErrors
++;
357 memcpy(key
->rx_pn
, pn
, CCMP_PN_LEN
);
359 /* Remove hdr and MIC */
360 memmove(skb
->data
+ CCMP_HDR_LEN
, skb
->data
, hdr_len
);
361 skb_pull(skb
, CCMP_HDR_LEN
);
362 skb_trim(skb
, skb
->len
- CCMP_MIC_LEN
);
368 static int ieee80211_ccmp_set_key(void *key
, int len
, u8
*seq
, void *priv
)
370 struct ieee80211_ccmp_data
*data
= priv
;
372 struct crypto_tfm
*tfm
= data
->tfm
;
374 keyidx
= data
->key_idx
;
375 memset(data
, 0, sizeof(*data
));
376 data
->key_idx
= keyidx
;
378 if (len
== CCMP_TK_LEN
) {
379 memcpy(data
->key
, key
, CCMP_TK_LEN
);
382 data
->rx_pn
[0] = seq
[5];
383 data
->rx_pn
[1] = seq
[4];
384 data
->rx_pn
[2] = seq
[3];
385 data
->rx_pn
[3] = seq
[2];
386 data
->rx_pn
[4] = seq
[1];
387 data
->rx_pn
[5] = seq
[0];
389 crypto_cipher_setkey(data
->tfm
, data
->key
, CCMP_TK_LEN
);
399 static int ieee80211_ccmp_get_key(void *key
, int len
, u8
*seq
, void *priv
)
401 struct ieee80211_ccmp_data
*data
= priv
;
403 if (len
< CCMP_TK_LEN
)
408 memcpy(key
, data
->key
, CCMP_TK_LEN
);
411 seq
[0] = data
->tx_pn
[5];
412 seq
[1] = data
->tx_pn
[4];
413 seq
[2] = data
->tx_pn
[3];
414 seq
[3] = data
->tx_pn
[2];
415 seq
[4] = data
->tx_pn
[1];
416 seq
[5] = data
->tx_pn
[0];
423 static char * ieee80211_ccmp_print_stats(char *p
, void *priv
)
425 struct ieee80211_ccmp_data
*ccmp
= priv
;
426 p
+= sprintf(p
, "key[%d] alg=CCMP key_set=%d "
427 "tx_pn=%02x%02x%02x%02x%02x%02x "
428 "rx_pn=%02x%02x%02x%02x%02x%02x "
429 "format_errors=%d replays=%d decrypt_errors=%d\n",
430 ccmp
->key_idx
, ccmp
->key_set
,
431 MAC_ARG(ccmp
->tx_pn
), MAC_ARG(ccmp
->rx_pn
),
432 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
433 ccmp
->dot11RSNAStatsCCMPReplays
,
434 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
440 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp
= {
442 .init
= ieee80211_ccmp_init
,
443 .deinit
= ieee80211_ccmp_deinit
,
444 .encrypt_mpdu
= ieee80211_ccmp_encrypt
,
445 .decrypt_mpdu
= ieee80211_ccmp_decrypt
,
446 .encrypt_msdu
= NULL
,
447 .decrypt_msdu
= NULL
,
448 .set_key
= ieee80211_ccmp_set_key
,
449 .get_key
= ieee80211_ccmp_get_key
,
450 .print_stats
= ieee80211_ccmp_print_stats
,
451 .extra_prefix_len
= CCMP_HDR_LEN
,
452 .extra_postfix_len
= CCMP_MIC_LEN
,
453 .owner
= THIS_MODULE
,
457 static int __init
ieee80211_crypto_ccmp_init(void)
459 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp
);
463 static void __exit
ieee80211_crypto_ccmp_exit(void)
465 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp
);
469 module_init(ieee80211_crypto_ccmp_init
);
470 module_exit(ieee80211_crypto_ccmp_exit
);