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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/random.h>
17 #include <linux/skbuff.h>
18 #include <linux/netdevice.h>
19 #include <linux/if_ether.h>
20 #include <linux/if_arp.h>
21 #include <linux/string.h>
22 #include <linux/wireless.h>
24 #include "ieee80211.h"
26 #include <linux/crypto.h>
27 #include <linux/scatterlist.h>
29 MODULE_AUTHOR("Jouni Malinen");
30 MODULE_DESCRIPTION("Host AP crypt: CCMP");
31 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 void ieee80211_ccmp_aes_encrypt(struct crypto_tfm
*tfm
,
62 const u8 pt
[16], u8 ct
[16])
64 crypto_cipher_encrypt_one((void *)tfm
, ct
, pt
);
67 static void *ieee80211_ccmp_init(int key_idx
)
69 struct ieee80211_ccmp_data
*priv
;
71 priv
= kzalloc(sizeof(*priv
), GFP_ATOMIC
);
74 priv
->key_idx
= key_idx
;
76 priv
->tfm
= (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC
);
77 if (IS_ERR(priv
->tfm
)) {
78 pr_debug("could not allocate crypto API aes\n");
88 crypto_free_cipher((void *)priv
->tfm
);
96 static void ieee80211_ccmp_deinit(void *priv
)
98 struct ieee80211_ccmp_data
*_priv
= priv
;
100 if (_priv
&& _priv
->tfm
)
101 crypto_free_cipher((void *)_priv
->tfm
);
106 static inline void xor_block(u8
*b
, u8
*a
, size_t len
)
109 for (i
= 0; i
< len
; i
++)
113 static void ccmp_init_blocks(struct crypto_tfm
*tfm
,
114 struct ieee80211_hdr_4addr
*hdr
,
115 u8
*pn
, size_t dlen
, u8
*b0
, u8
*auth
,
121 int a4_included
, qc_included
;
122 u8 aad
[2 * AES_BLOCK_LEN
];
124 fc
= le16_to_cpu(hdr
->frame_ctl
);
125 a4_included
= ((fc
& (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
)) ==
126 (IEEE80211_FCTL_TODS
| IEEE80211_FCTL_FROMDS
));
128 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
129 (WLAN_FC_GET_STYPE(fc) & 0x08));
131 qc_included
= ((WLAN_FC_GET_TYPE(fc
) == IEEE80211_FTYPE_DATA
) &&
132 (WLAN_FC_GET_STYPE(fc
) & 0x80));
137 pos
= (u8
*) &hdr
->addr4
;
143 /* CCM Initial Block:
144 * Flag (Include authentication header, M=3 (8-octet MIC),
145 * L=1 (2-octet Dlen))
146 * Nonce: 0x00 | A2 | PN
150 memcpy(b0
+ 2, hdr
->addr2
, ETH_ALEN
);
151 memcpy(b0
+ 8, pn
, CCMP_PN_LEN
);
152 b0
[14] = (dlen
>> 8) & 0xff;
153 b0
[15] = dlen
& 0xff;
156 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
158 * SC with bits 4..15 (seq#) masked to zero
163 aad
[0] = 0; /* aad_len >> 8 */
164 aad
[1] = aad_len
& 0xff;
165 aad
[2] = pos
[0] & 0x8f;
166 aad
[3] = pos
[1] & 0xc7;
167 memcpy(aad
+ 4, hdr
->addr1
, 3 * ETH_ALEN
);
168 pos
= (u8
*) &hdr
->seq_ctl
;
169 aad
[22] = pos
[0] & 0x0f;
170 aad
[23] = 0; /* all bits masked */
171 memset(aad
+ 24, 0, 8);
173 memcpy(aad
+ 24, hdr
->addr4
, ETH_ALEN
);
175 aad
[a4_included
? 30 : 24] = qc
;
176 /* rest of QC masked */
179 /* Start with the first block and AAD */
180 ieee80211_ccmp_aes_encrypt(tfm
, b0
, auth
);
181 xor_block(auth
, aad
, AES_BLOCK_LEN
);
182 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
183 xor_block(auth
, &aad
[AES_BLOCK_LEN
], AES_BLOCK_LEN
);
184 ieee80211_ccmp_aes_encrypt(tfm
, auth
, auth
);
187 ieee80211_ccmp_aes_encrypt(tfm
, b0
, s0
);
190 static int ieee80211_ccmp_encrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
192 struct ieee80211_ccmp_data
*key
= priv
;
195 struct ieee80211_hdr_4addr
*hdr
;
196 int blocks
, last
, len
;
203 if (skb_headroom(skb
) < CCMP_HDR_LEN
||
204 skb_tailroom(skb
) < CCMP_MIC_LEN
||
208 data_len
= skb
->len
- hdr_len
;
209 pos
= skb_push(skb
, CCMP_HDR_LEN
);
210 memmove(pos
, pos
+ CCMP_HDR_LEN
, hdr_len
);
216 if (key
->tx_pn
[i
] != 0)
221 *pos
++ = key
->tx_pn
[5];
222 *pos
++ = key
->tx_pn
[4];
224 *pos
++ = (key
->key_idx
<< 6) | (1 << 5) /* Ext IV included */;
225 *pos
++ = key
->tx_pn
[3];
226 *pos
++ = key
->tx_pn
[2];
227 *pos
++ = key
->tx_pn
[1];
228 *pos
++ = key
->tx_pn
[0];
230 hdr
= (struct ieee80211_hdr_4addr
*)skb
->data
;
231 mic
= skb_put(skb
, CCMP_MIC_LEN
);
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
];
258 static int ieee80211_ccmp_decrypt(struct sk_buff
*skb
, int hdr_len
, void *priv
)
260 struct ieee80211_ccmp_data
*key
= priv
;
262 struct ieee80211_hdr_4addr
*hdr
;
264 size_t data_len
= skb
->len
- hdr_len
- CCMP_HDR_LEN
- CCMP_MIC_LEN
;
265 u8
*mic
= skb
->data
+ skb
->len
- CCMP_MIC_LEN
;
269 int i
, blocks
, last
, len
;
271 if (skb
->len
< hdr_len
+ CCMP_HDR_LEN
+ CCMP_MIC_LEN
) {
272 key
->dot11RSNAStatsCCMPFormatErrors
++;
276 hdr
= (struct ieee80211_hdr_4addr
*)skb
->data
;
277 pos
= skb
->data
+ hdr_len
;
279 if (!(keyidx
& (1 << 5))) {
280 if (net_ratelimit()) {
281 pr_debug("received packet without ExtIV flag from %pM\n",
284 key
->dot11RSNAStatsCCMPFormatErrors
++;
288 if (key
->key_idx
!= keyidx
) {
289 pr_debug("RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
290 key
->key_idx
, keyidx
, priv
);
294 if (net_ratelimit()) {
295 pr_debug("received packet from %pM with keyid=%d that does not have a configured key\n",
309 if (memcmp(pn
, key
->rx_pn
, CCMP_PN_LEN
) <= 0) {
310 if (net_ratelimit()) {
311 pr_debug("replay detected: STA=%pM previous PN %pm received PN %pm\n",
312 hdr
->addr2
, key
->rx_pn
, pn
);
314 key
->dot11RSNAStatsCCMPReplays
++;
318 ccmp_init_blocks(key
->tfm
, hdr
, pn
, data_len
, b0
, a
, b
);
319 xor_block(mic
, b
, CCMP_MIC_LEN
);
321 blocks
= (data_len
+ AES_BLOCK_LEN
- 1) / AES_BLOCK_LEN
;
322 last
= data_len
% AES_BLOCK_LEN
;
324 for (i
= 1; i
<= blocks
; i
++) {
325 len
= (i
== blocks
&& last
) ? last
: AES_BLOCK_LEN
;
326 /* Decrypt, with counter */
327 b0
[14] = (i
>> 8) & 0xff;
329 ieee80211_ccmp_aes_encrypt(key
->tfm
, b0
, b
);
330 xor_block(pos
, b
, len
);
332 xor_block(a
, pos
, len
);
333 ieee80211_ccmp_aes_encrypt(key
->tfm
, a
, a
);
337 if (memcmp(mic
, a
, CCMP_MIC_LEN
) != 0) {
339 pr_debug("decrypt failed: STA=%pM\n", hdr
->addr2
);
341 key
->dot11RSNAStatsCCMPDecryptErrors
++;
345 memcpy(key
->rx_pn
, pn
, CCMP_PN_LEN
);
347 /* Remove hdr and MIC */
348 memmove(skb
->data
+ CCMP_HDR_LEN
, skb
->data
, hdr_len
);
349 skb_pull(skb
, CCMP_HDR_LEN
);
350 skb_trim(skb
, skb
->len
- CCMP_MIC_LEN
);
356 static int ieee80211_ccmp_set_key(void *key
, int len
, u8
*seq
, void *priv
)
358 struct ieee80211_ccmp_data
*data
= priv
;
360 struct crypto_tfm
*tfm
= data
->tfm
;
362 keyidx
= data
->key_idx
;
363 memset(data
, 0, sizeof(*data
));
364 data
->key_idx
= keyidx
;
366 if (len
== CCMP_TK_LEN
) {
367 memcpy(data
->key
, key
, CCMP_TK_LEN
);
370 data
->rx_pn
[0] = seq
[5];
371 data
->rx_pn
[1] = seq
[4];
372 data
->rx_pn
[2] = seq
[3];
373 data
->rx_pn
[3] = seq
[2];
374 data
->rx_pn
[4] = seq
[1];
375 data
->rx_pn
[5] = seq
[0];
377 crypto_cipher_setkey((void *)data
->tfm
, data
->key
, CCMP_TK_LEN
);
387 static int ieee80211_ccmp_get_key(void *key
, int len
, u8
*seq
, void *priv
)
389 struct ieee80211_ccmp_data
*data
= priv
;
391 if (len
< CCMP_TK_LEN
)
396 memcpy(key
, data
->key
, CCMP_TK_LEN
);
399 seq
[0] = data
->tx_pn
[5];
400 seq
[1] = data
->tx_pn
[4];
401 seq
[2] = data
->tx_pn
[3];
402 seq
[3] = data
->tx_pn
[2];
403 seq
[4] = data
->tx_pn
[1];
404 seq
[5] = data
->tx_pn
[0];
411 static char *ieee80211_ccmp_print_stats(char *p
, void *priv
)
413 struct ieee80211_ccmp_data
*ccmp
= priv
;
415 "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n",
416 ccmp
->key_idx
, ccmp
->key_set
,
417 ccmp
->tx_pn
, ccmp
->rx_pn
,
418 ccmp
->dot11RSNAStatsCCMPFormatErrors
,
419 ccmp
->dot11RSNAStatsCCMPReplays
,
420 ccmp
->dot11RSNAStatsCCMPDecryptErrors
);
425 void ieee80211_ccmp_null(void)
429 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp
= {
431 .init
= ieee80211_ccmp_init
,
432 .deinit
= ieee80211_ccmp_deinit
,
433 .encrypt_mpdu
= ieee80211_ccmp_encrypt
,
434 .decrypt_mpdu
= ieee80211_ccmp_decrypt
,
435 .encrypt_msdu
= NULL
,
436 .decrypt_msdu
= NULL
,
437 .set_key
= ieee80211_ccmp_set_key
,
438 .get_key
= ieee80211_ccmp_get_key
,
439 .print_stats
= ieee80211_ccmp_print_stats
,
440 .extra_prefix_len
= CCMP_HDR_LEN
,
441 .extra_postfix_len
= CCMP_MIC_LEN
,
442 .owner
= THIS_MODULE
,
446 int ieee80211_crypto_ccmp_init(void)
448 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp
);
452 void ieee80211_crypto_ccmp_exit(void)
454 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp
);