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ieee80211_crypt_ccmp.c
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1 /*
2  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
3  *
4  * Copyright (c) 2003-2004, Jouni Malinen <[email protected]>
5  *
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
9  * more details.
10  */
11 
12 //#include <linux/config.h>
13 #include <linux/module.h>
14 #include <linux/init.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 <asm/string.h>
22 #include <linux/wireless.h>
23 
24 #include "ieee80211.h"
25 
26 #include <linux/crypto.h>
27 #include <linux/scatterlist.h>
28 
29 MODULE_AUTHOR("Jouni Malinen");
30 MODULE_DESCRIPTION("Host AP crypt: CCMP");
31 MODULE_LICENSE("GPL");
32 
33 
34 #define AES_BLOCK_LEN 16
35 #define CCMP_HDR_LEN 8
36 #define CCMP_MIC_LEN 8
37 #define CCMP_TK_LEN 16
38 #define CCMP_PN_LEN 6
39 
42  int key_set;
43 
46 
50 
51  int key_idx;
52 
53  struct crypto_tfm *tfm;
54 
55  /* scratch buffers for virt_to_page() (crypto API) */
59 };
60 
62  const u8 pt[16], u8 ct[16])
63 {
64  crypto_cipher_encrypt_one((void *)tfm, ct, pt);
65 }
66 
67 static void * ieee80211_ccmp_init(int key_idx)
68 {
69  struct ieee80211_ccmp_data *priv;
70 
71  priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
72  if (priv == NULL)
73  goto fail;
74  priv->key_idx = key_idx;
75 
76  priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
77  if (IS_ERR(priv->tfm)) {
78  printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
79  "crypto API aes\n");
80  priv->tfm = NULL;
81  goto fail;
82  }
83 
84  return priv;
85 
86 fail:
87  if (priv) {
88  if (priv->tfm)
89  crypto_free_cipher((void *)priv->tfm);
90  kfree(priv);
91  }
92 
93  return NULL;
94 }
95 
96 
97 static void ieee80211_ccmp_deinit(void *priv)
98 {
99  struct ieee80211_ccmp_data *_priv = priv;
100 
101  if (_priv && _priv->tfm)
102  crypto_free_cipher((void *)_priv->tfm);
103  kfree(priv);
104 }
105 
106 
107 static inline void xor_block(u8 *b, u8 *a, size_t len)
108 {
109  int i;
110  for (i = 0; i < len; i++)
111  b[i] ^= a[i];
112 }
113 
114 static void ccmp_init_blocks(struct crypto_tfm *tfm,
115  struct ieee80211_hdr_4addr *hdr,
116  u8 *pn, size_t dlen, u8 *b0, u8 *auth,
117  u8 *s0)
118 {
119  u8 *pos, qc = 0;
120  size_t aad_len;
121  u16 fc;
122  int a4_included, qc_included;
123  u8 aad[2 * AES_BLOCK_LEN];
124 
125  fc = le16_to_cpu(hdr->frame_ctl);
126  a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
128  /*
129  qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
130  (WLAN_FC_GET_STYPE(fc) & 0x08));
131  */
132  // fixed by David :2006.9.6
133  qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
134  (WLAN_FC_GET_STYPE(fc) & 0x80));
135  aad_len = 22;
136  if (a4_included)
137  aad_len += 6;
138  if (qc_included) {
139  pos = (u8 *) &hdr->addr4;
140  if (a4_included)
141  pos += 6;
142  qc = *pos & 0x0f;
143  aad_len += 2;
144  }
145  /* CCM Initial Block:
146  * Flag (Include authentication header, M=3 (8-octet MIC),
147  * L=1 (2-octet Dlen))
148  * Nonce: 0x00 | A2 | PN
149  * Dlen */
150  b0[0] = 0x59;
151  b0[1] = qc;
152  memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
153  memcpy(b0 + 8, pn, CCMP_PN_LEN);
154  b0[14] = (dlen >> 8) & 0xff;
155  b0[15] = dlen & 0xff;
156 
157  /* AAD:
158  * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
159  * A1 | A2 | A3
160  * SC with bits 4..15 (seq#) masked to zero
161  * A4 (if present)
162  * QC (if present)
163  */
164  pos = (u8 *) hdr;
165  aad[0] = 0; /* aad_len >> 8 */
166  aad[1] = aad_len & 0xff;
167  aad[2] = pos[0] & 0x8f;
168  aad[3] = pos[1] & 0xc7;
169  memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
170  pos = (u8 *) &hdr->seq_ctl;
171  aad[22] = pos[0] & 0x0f;
172  aad[23] = 0; /* all bits masked */
173  memset(aad + 24, 0, 8);
174  if (a4_included)
175  memcpy(aad + 24, hdr->addr4, ETH_ALEN);
176  if (qc_included) {
177  aad[a4_included ? 30 : 24] = qc;
178  /* rest of QC masked */
179  }
180 
181  /* Start with the first block and AAD */
182  ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
183  xor_block(auth, aad, AES_BLOCK_LEN);
184  ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
185  xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
186  ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
187  b0[0] &= 0x07;
188  b0[14] = b0[15] = 0;
189  ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
190 }
191 
192 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
193 {
194  struct ieee80211_ccmp_data *key = priv;
195  int data_len, i;
196  u8 *pos;
197  struct ieee80211_hdr_4addr *hdr;
198  int blocks, last, len;
199  u8 *mic;
200  u8 *b0 = key->tx_b0;
201  u8 *b = key->tx_b;
202  u8 *e = key->tx_e;
203  u8 *s0 = key->tx_s0;
204 
205  if (skb_headroom(skb) < CCMP_HDR_LEN ||
206  skb_tailroom(skb) < CCMP_MIC_LEN ||
207  skb->len < hdr_len)
208  return -1;
209 
210  data_len = skb->len - hdr_len;
211  pos = skb_push(skb, CCMP_HDR_LEN);
212  memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
213  pos += hdr_len;
214 // mic = skb_put(skb, CCMP_MIC_LEN);
215 
216  i = CCMP_PN_LEN - 1;
217  while (i >= 0) {
218  key->tx_pn[i]++;
219  if (key->tx_pn[i] != 0)
220  break;
221  i--;
222  }
223 
224  *pos++ = key->tx_pn[5];
225  *pos++ = key->tx_pn[4];
226  *pos++ = 0;
227  *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
228  *pos++ = key->tx_pn[3];
229  *pos++ = key->tx_pn[2];
230  *pos++ = key->tx_pn[1];
231  *pos++ = key->tx_pn[0];
232 
233  hdr = (struct ieee80211_hdr_4addr *)skb->data;
234  //mic is moved to here by john
235  mic = skb_put(skb, CCMP_MIC_LEN);
236 
237  ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
238 
239  blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
240  last = data_len % AES_BLOCK_LEN;
241 
242  for (i = 1; i <= blocks; i++) {
243  len = (i == blocks && last) ? last : AES_BLOCK_LEN;
244  /* Authentication */
245  xor_block(b, pos, len);
246  ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
247  /* Encryption, with counter */
248  b0[14] = (i >> 8) & 0xff;
249  b0[15] = i & 0xff;
250  ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
251  xor_block(pos, e, len);
252  pos += len;
253  }
254 
255  for (i = 0; i < CCMP_MIC_LEN; i++)
256  mic[i] = b[i] ^ s0[i];
257 
258  return 0;
259 }
260 
261 
262 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
263 {
264  struct ieee80211_ccmp_data *key = priv;
265  u8 keyidx, *pos;
266  struct ieee80211_hdr_4addr *hdr;
267  u8 pn[6];
268  size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
269  u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
270  u8 *b0 = key->rx_b0;
271  u8 *b = key->rx_b;
272  u8 *a = key->rx_a;
273  int i, blocks, last, len;
274 
275  if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
277  return -1;
278  }
279 
280  hdr = (struct ieee80211_hdr_4addr *)skb->data;
281  pos = skb->data + hdr_len;
282  keyidx = pos[3];
283  if (!(keyidx & (1 << 5))) {
284  if (net_ratelimit()) {
285  printk(KERN_DEBUG "CCMP: received packet without ExtIV"
286  " flag from %pM\n", hdr->addr2);
287  }
289  return -2;
290  }
291  keyidx >>= 6;
292  if (key->key_idx != keyidx) {
293  printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
294  "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
295  return -6;
296  }
297  if (!key->key_set) {
298  if (net_ratelimit()) {
299  printk(KERN_DEBUG "CCMP: received packet from %pM"
300  " with keyid=%d that does not have a configured"
301  " key\n", hdr->addr2, keyidx);
302  }
303  return -3;
304  }
305 
306  pn[0] = pos[7];
307  pn[1] = pos[6];
308  pn[2] = pos[5];
309  pn[3] = pos[4];
310  pn[4] = pos[1];
311  pn[5] = pos[0];
312  pos += 8;
313 
314  if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
315  if (net_ratelimit()) {
316  printk(KERN_DEBUG "CCMP: replay detected: STA=%pM"
317  " previous PN %pm received PN %pm\n",
318  hdr->addr2, key->rx_pn, pn);
319  }
321  return -4;
322  }
323 
324  ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
325  xor_block(mic, b, CCMP_MIC_LEN);
326 
327  blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
328  last = data_len % AES_BLOCK_LEN;
329 
330  for (i = 1; i <= blocks; i++) {
331  len = (i == blocks && last) ? last : AES_BLOCK_LEN;
332  /* Decrypt, with counter */
333  b0[14] = (i >> 8) & 0xff;
334  b0[15] = i & 0xff;
335  ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
336  xor_block(pos, b, len);
337  /* Authentication */
338  xor_block(a, pos, len);
339  ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
340  pos += len;
341  }
342 
343  if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
344  if (net_ratelimit()) {
345  printk(KERN_DEBUG "CCMP: decrypt failed: STA="
346  "%pM\n", hdr->addr2);
347  }
349  return -5;
350  }
351 
352  memcpy(key->rx_pn, pn, CCMP_PN_LEN);
353 
354  /* Remove hdr and MIC */
355  memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
356  skb_pull(skb, CCMP_HDR_LEN);
357  skb_trim(skb, skb->len - CCMP_MIC_LEN);
358 
359  return keyidx;
360 }
361 
362 
363 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
364 {
365  struct ieee80211_ccmp_data *data = priv;
366  int keyidx;
367  struct crypto_tfm *tfm = data->tfm;
368 
369  keyidx = data->key_idx;
370  memset(data, 0, sizeof(*data));
371  data->key_idx = keyidx;
372  data->tfm = tfm;
373  if (len == CCMP_TK_LEN) {
374  memcpy(data->key, key, CCMP_TK_LEN);
375  data->key_set = 1;
376  if (seq) {
377  data->rx_pn[0] = seq[5];
378  data->rx_pn[1] = seq[4];
379  data->rx_pn[2] = seq[3];
380  data->rx_pn[3] = seq[2];
381  data->rx_pn[4] = seq[1];
382  data->rx_pn[5] = seq[0];
383  }
384  crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
385  } else if (len == 0)
386  data->key_set = 0;
387  else
388  return -1;
389 
390  return 0;
391 }
392 
393 
394 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
395 {
396  struct ieee80211_ccmp_data *data = priv;
397 
398  if (len < CCMP_TK_LEN)
399  return -1;
400 
401  if (!data->key_set)
402  return 0;
403  memcpy(key, data->key, CCMP_TK_LEN);
404 
405  if (seq) {
406  seq[0] = data->tx_pn[5];
407  seq[1] = data->tx_pn[4];
408  seq[2] = data->tx_pn[3];
409  seq[3] = data->tx_pn[2];
410  seq[4] = data->tx_pn[1];
411  seq[5] = data->tx_pn[0];
412  }
413 
414  return CCMP_TK_LEN;
415 }
416 
417 
418 static char * ieee80211_ccmp_print_stats(char *p, void *priv)
419 {
420  struct ieee80211_ccmp_data *ccmp = priv;
421  p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
422  "tx_pn=%pm rx_pn=%pm "
423  "format_errors=%d replays=%d decrypt_errors=%d\n",
424  ccmp->key_idx, ccmp->key_set,
425  ccmp->tx_pn, ccmp->rx_pn,
429 
430  return p;
431 }
432 
434 {
435 // printk("============>%s()\n", __func__);
436  return;
437 }
438 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
439  .name = "CCMP",
440  .init = ieee80211_ccmp_init,
441  .deinit = ieee80211_ccmp_deinit,
442  .encrypt_mpdu = ieee80211_ccmp_encrypt,
443  .decrypt_mpdu = ieee80211_ccmp_decrypt,
444  .encrypt_msdu = NULL,
445  .decrypt_msdu = NULL,
446  .set_key = ieee80211_ccmp_set_key,
447  .get_key = ieee80211_ccmp_get_key,
448  .print_stats = ieee80211_ccmp_print_stats,
449  .extra_prefix_len = CCMP_HDR_LEN,
450  .extra_postfix_len = CCMP_MIC_LEN,
451  .owner = THIS_MODULE,
452 };
453 
454 
456 {
457  return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
458 }
459 
460 
462 {
463  ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
464 }