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TOMOYO Linux Cross Reference
Linux/net/mac80211/wpa.c

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  1 /*
  2  * Copyright 2002-2004, Instant802 Networks, Inc.
  3  * Copyright 2008, Jouni Malinen <j@w1.fi>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation.
  8  */
  9 
 10 #include <linux/netdevice.h>
 11 #include <linux/types.h>
 12 #include <linux/skbuff.h>
 13 #include <linux/compiler.h>
 14 #include <linux/ieee80211.h>
 15 #include <linux/gfp.h>
 16 #include <asm/unaligned.h>
 17 #include <net/mac80211.h>
 18 #include <crypto/aes.h>
 19 
 20 #include "ieee80211_i.h"
 21 #include "michael.h"
 22 #include "tkip.h"
 23 #include "aes_ccm.h"
 24 #include "aes_cmac.h"
 25 #include "wpa.h"
 26 
 27 ieee80211_tx_result
 28 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
 29 {
 30         u8 *data, *key, *mic;
 31         size_t data_len;
 32         unsigned int hdrlen;
 33         struct ieee80211_hdr *hdr;
 34         struct sk_buff *skb = tx->skb;
 35         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 36         int tail;
 37 
 38         hdr = (struct ieee80211_hdr *)skb->data;
 39         if (!tx->key || tx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
 40             skb->len < 24 || !ieee80211_is_data_present(hdr->frame_control))
 41                 return TX_CONTINUE;
 42 
 43         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 44         if (skb->len < hdrlen)
 45                 return TX_DROP;
 46 
 47         data = skb->data + hdrlen;
 48         data_len = skb->len - hdrlen;
 49 
 50         if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) {
 51                 /* Need to use software crypto for the test */
 52                 info->control.hw_key = NULL;
 53         }
 54 
 55         if (info->control.hw_key &&
 56             (info->flags & IEEE80211_TX_CTL_DONTFRAG ||
 57              tx->local->ops->set_frag_threshold) &&
 58             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
 59                 /* hwaccel - with no need for SW-generated MMIC */
 60                 return TX_CONTINUE;
 61         }
 62 
 63         tail = MICHAEL_MIC_LEN;
 64         if (!info->control.hw_key)
 65                 tail += IEEE80211_TKIP_ICV_LEN;
 66 
 67         if (WARN_ON(skb_tailroom(skb) < tail ||
 68                     skb_headroom(skb) < IEEE80211_TKIP_IV_LEN))
 69                 return TX_DROP;
 70 
 71         key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
 72         mic = skb_put(skb, MICHAEL_MIC_LEN);
 73         michael_mic(key, hdr, data, data_len, mic);
 74         if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
 75                 mic[0]++;
 76 
 77         return TX_CONTINUE;
 78 }
 79 
 80 
 81 ieee80211_rx_result
 82 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
 83 {
 84         u8 *data, *key = NULL;
 85         size_t data_len;
 86         unsigned int hdrlen;
 87         u8 mic[MICHAEL_MIC_LEN];
 88         struct sk_buff *skb = rx->skb;
 89         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 90         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 91 
 92         /*
 93          * it makes no sense to check for MIC errors on anything other
 94          * than data frames.
 95          */
 96         if (!ieee80211_is_data_present(hdr->frame_control))
 97                 return RX_CONTINUE;
 98 
 99         /*
100          * No way to verify the MIC if the hardware stripped it or
101          * the IV with the key index. In this case we have solely rely
102          * on the driver to set RX_FLAG_MMIC_ERROR in the event of a
103          * MIC failure report.
104          */
105         if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) {
106                 if (status->flag & RX_FLAG_MMIC_ERROR)
107                         goto mic_fail_no_key;
108 
109                 if (!(status->flag & RX_FLAG_IV_STRIPPED) && rx->key &&
110                     rx->key->conf.cipher == WLAN_CIPHER_SUITE_TKIP)
111                         goto update_iv;
112 
113                 return RX_CONTINUE;
114         }
115 
116         /*
117          * Some hardware seems to generate Michael MIC failure reports; even
118          * though, the frame was not encrypted with TKIP and therefore has no
119          * MIC. Ignore the flag them to avoid triggering countermeasures.
120          */
121         if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
122             !(status->flag & RX_FLAG_DECRYPTED))
123                 return RX_CONTINUE;
124 
125         if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) {
126                 /*
127                  * APs with pairwise keys should never receive Michael MIC
128                  * errors for non-zero keyidx because these are reserved for
129                  * group keys and only the AP is sending real multicast
130                  * frames in the BSS. (
131                  */
132                 return RX_DROP_UNUSABLE;
133         }
134 
135         if (status->flag & RX_FLAG_MMIC_ERROR)
136                 goto mic_fail;
137 
138         hdrlen = ieee80211_hdrlen(hdr->frame_control);
139         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
140                 return RX_DROP_UNUSABLE;
141 
142         if (skb_linearize(rx->skb))
143                 return RX_DROP_UNUSABLE;
144         hdr = (void *)skb->data;
145 
146         data = skb->data + hdrlen;
147         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
148         key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
149         michael_mic(key, hdr, data, data_len, mic);
150         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
151                 goto mic_fail;
152 
153         /* remove Michael MIC from payload */
154         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
155 
156 update_iv:
157         /* update IV in key information to be able to detect replays */
158         rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
159         rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;
160 
161         return RX_CONTINUE;
162 
163 mic_fail:
164         rx->key->u.tkip.mic_failures++;
165 
166 mic_fail_no_key:
167         /*
168          * In some cases the key can be unset - e.g. a multicast packet, in
169          * a driver that supports HW encryption. Send up the key idx only if
170          * the key is set.
171          */
172         mac80211_ev_michael_mic_failure(rx->sdata,
173                                         rx->key ? rx->key->conf.keyidx : -1,
174                                         (void *) skb->data, NULL, GFP_ATOMIC);
175         return RX_DROP_UNUSABLE;
176 }
177 
178 
179 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
180 {
181         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
182         struct ieee80211_key *key = tx->key;
183         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
184         unsigned int hdrlen;
185         int len, tail;
186         u8 *pos;
187 
188         if (info->control.hw_key &&
189             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
190             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
191                 /* hwaccel - with no need for software-generated IV */
192                 return 0;
193         }
194 
195         hdrlen = ieee80211_hdrlen(hdr->frame_control);
196         len = skb->len - hdrlen;
197 
198         if (info->control.hw_key)
199                 tail = 0;
200         else
201                 tail = IEEE80211_TKIP_ICV_LEN;
202 
203         if (WARN_ON(skb_tailroom(skb) < tail ||
204                     skb_headroom(skb) < IEEE80211_TKIP_IV_LEN))
205                 return -1;
206 
207         pos = skb_push(skb, IEEE80211_TKIP_IV_LEN);
208         memmove(pos, pos + IEEE80211_TKIP_IV_LEN, hdrlen);
209         skb_set_network_header(skb, skb_network_offset(skb) +
210                                     IEEE80211_TKIP_IV_LEN);
211         pos += hdrlen;
212 
213         /* the HW only needs room for the IV, but not the actual IV */
214         if (info->control.hw_key &&
215             (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
216                 return 0;
217 
218         /* Increase IV for the frame */
219         spin_lock(&key->u.tkip.txlock);
220         key->u.tkip.tx.iv16++;
221         if (key->u.tkip.tx.iv16 == 0)
222                 key->u.tkip.tx.iv32++;
223         pos = ieee80211_tkip_add_iv(pos, key);
224         spin_unlock(&key->u.tkip.txlock);
225 
226         /* hwaccel - with software IV */
227         if (info->control.hw_key)
228                 return 0;
229 
230         /* Add room for ICV */
231         skb_put(skb, IEEE80211_TKIP_ICV_LEN);
232 
233         return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
234                                            key, skb, pos, len);
235 }
236 
237 
238 ieee80211_tx_result
239 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
240 {
241         struct sk_buff *skb;
242 
243         ieee80211_tx_set_protected(tx);
244 
245         skb_queue_walk(&tx->skbs, skb) {
246                 if (tkip_encrypt_skb(tx, skb) < 0)
247                         return TX_DROP;
248         }
249 
250         return TX_CONTINUE;
251 }
252 
253 
254 ieee80211_rx_result
255 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
256 {
257         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
258         int hdrlen, res, hwaccel = 0;
259         struct ieee80211_key *key = rx->key;
260         struct sk_buff *skb = rx->skb;
261         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
262 
263         hdrlen = ieee80211_hdrlen(hdr->frame_control);
264 
265         if (!ieee80211_is_data(hdr->frame_control))
266                 return RX_CONTINUE;
267 
268         if (!rx->sta || skb->len - hdrlen < 12)
269                 return RX_DROP_UNUSABLE;
270 
271         /* it may be possible to optimize this a bit more */
272         if (skb_linearize(rx->skb))
273                 return RX_DROP_UNUSABLE;
274         hdr = (void *)skb->data;
275 
276         /*
277          * Let TKIP code verify IV, but skip decryption.
278          * In the case where hardware checks the IV as well,
279          * we don't even get here, see ieee80211_rx_h_decrypt()
280          */
281         if (status->flag & RX_FLAG_DECRYPTED)
282                 hwaccel = 1;
283 
284         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
285                                           key, skb->data + hdrlen,
286                                           skb->len - hdrlen, rx->sta->sta.addr,
287                                           hdr->addr1, hwaccel, rx->security_idx,
288                                           &rx->tkip_iv32,
289                                           &rx->tkip_iv16);
290         if (res != TKIP_DECRYPT_OK)
291                 return RX_DROP_UNUSABLE;
292 
293         /* Trim ICV */
294         skb_trim(skb, skb->len - IEEE80211_TKIP_ICV_LEN);
295 
296         /* Remove IV */
297         memmove(skb->data + IEEE80211_TKIP_IV_LEN, skb->data, hdrlen);
298         skb_pull(skb, IEEE80211_TKIP_IV_LEN);
299 
300         return RX_CONTINUE;
301 }
302 
303 
304 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
305                                 int encrypted)
306 {
307         __le16 mask_fc;
308         int a4_included, mgmt;
309         u8 qos_tid;
310         u16 len_a;
311         unsigned int hdrlen;
312         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
313 
314         /*
315          * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
316          * Retry, PwrMgt, MoreData; set Protected
317          */
318         mgmt = ieee80211_is_mgmt(hdr->frame_control);
319         mask_fc = hdr->frame_control;
320         mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
321                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
322         if (!mgmt)
323                 mask_fc &= ~cpu_to_le16(0x0070);
324         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
325 
326         hdrlen = ieee80211_hdrlen(hdr->frame_control);
327         len_a = hdrlen - 2;
328         a4_included = ieee80211_has_a4(hdr->frame_control);
329 
330         if (ieee80211_is_data_qos(hdr->frame_control))
331                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
332         else
333                 qos_tid = 0;
334 
335         /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
336          * mode authentication are not allowed to collide, yet both are derived
337          * from this vector b_0. We only set L := 1 here to indicate that the
338          * data size can be represented in (L+1) bytes. The CCM layer will take
339          * care of storing the data length in the top (L+1) bytes and setting
340          * and clearing the other bits as is required to derive the two IVs.
341          */
342         b_0[0] = 0x1;
343 
344         /* Nonce: Nonce Flags | A2 | PN
345          * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
346          */
347         b_0[1] = qos_tid | (mgmt << 4);
348         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
349         memcpy(&b_0[8], pn, IEEE80211_CCMP_PN_LEN);
350 
351         /* AAD (extra authenticate-only data) / masked 802.11 header
352          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
353         put_unaligned_be16(len_a, &aad[0]);
354         put_unaligned(mask_fc, (__le16 *)&aad[2]);
355         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
356 
357         /* Mask Seq#, leave Frag# */
358         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
359         aad[23] = 0;
360 
361         if (a4_included) {
362                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
363                 aad[30] = qos_tid;
364                 aad[31] = 0;
365         } else {
366                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
367                 aad[24] = qos_tid;
368         }
369 }
370 
371 
372 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
373 {
374         hdr[0] = pn[5];
375         hdr[1] = pn[4];
376         hdr[2] = 0;
377         hdr[3] = 0x20 | (key_id << 6);
378         hdr[4] = pn[3];
379         hdr[5] = pn[2];
380         hdr[6] = pn[1];
381         hdr[7] = pn[0];
382 }
383 
384 
385 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
386 {
387         pn[0] = hdr[7];
388         pn[1] = hdr[6];
389         pn[2] = hdr[5];
390         pn[3] = hdr[4];
391         pn[4] = hdr[1];
392         pn[5] = hdr[0];
393 }
394 
395 
396 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
397 {
398         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
399         struct ieee80211_key *key = tx->key;
400         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
401         int hdrlen, len, tail;
402         u8 *pos;
403         u8 pn[6];
404         u64 pn64;
405         u8 aad[2 * AES_BLOCK_SIZE];
406         u8 b_0[AES_BLOCK_SIZE];
407 
408         if (info->control.hw_key &&
409             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
410             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
411                 /*
412                  * hwaccel has no need for preallocated room for CCMP
413                  * header or MIC fields
414                  */
415                 return 0;
416         }
417 
418         hdrlen = ieee80211_hdrlen(hdr->frame_control);
419         len = skb->len - hdrlen;
420 
421         if (info->control.hw_key)
422                 tail = 0;
423         else
424                 tail = IEEE80211_CCMP_MIC_LEN;
425 
426         if (WARN_ON(skb_tailroom(skb) < tail ||
427                     skb_headroom(skb) < IEEE80211_CCMP_HDR_LEN))
428                 return -1;
429 
430         pos = skb_push(skb, IEEE80211_CCMP_HDR_LEN);
431         memmove(pos, pos + IEEE80211_CCMP_HDR_LEN, hdrlen);
432         skb_set_network_header(skb, skb_network_offset(skb) +
433                                     IEEE80211_CCMP_HDR_LEN);
434 
435         /* the HW only needs room for the IV, but not the actual IV */
436         if (info->control.hw_key &&
437             (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
438                 return 0;
439 
440         hdr = (struct ieee80211_hdr *) pos;
441         pos += hdrlen;
442 
443         pn64 = atomic64_inc_return(&key->u.ccmp.tx_pn);
444 
445         pn[5] = pn64;
446         pn[4] = pn64 >> 8;
447         pn[3] = pn64 >> 16;
448         pn[2] = pn64 >> 24;
449         pn[1] = pn64 >> 32;
450         pn[0] = pn64 >> 40;
451 
452         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
453 
454         /* hwaccel - with software CCMP header */
455         if (info->control.hw_key)
456                 return 0;
457 
458         pos += IEEE80211_CCMP_HDR_LEN;
459         ccmp_special_blocks(skb, pn, b_0, aad, 0);
460         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
461                                   skb_put(skb, IEEE80211_CCMP_MIC_LEN));
462 
463         return 0;
464 }
465 
466 
467 ieee80211_tx_result
468 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
469 {
470         struct sk_buff *skb;
471 
472         ieee80211_tx_set_protected(tx);
473 
474         skb_queue_walk(&tx->skbs, skb) {
475                 if (ccmp_encrypt_skb(tx, skb) < 0)
476                         return TX_DROP;
477         }
478 
479         return TX_CONTINUE;
480 }
481 
482 
483 ieee80211_rx_result
484 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
485 {
486         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
487         int hdrlen;
488         struct ieee80211_key *key = rx->key;
489         struct sk_buff *skb = rx->skb;
490         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
491         u8 pn[IEEE80211_CCMP_PN_LEN];
492         int data_len;
493         int queue;
494 
495         hdrlen = ieee80211_hdrlen(hdr->frame_control);
496 
497         if (!ieee80211_is_data(hdr->frame_control) &&
498             !ieee80211_is_robust_mgmt_frame(hdr))
499                 return RX_CONTINUE;
500 
501         data_len = skb->len - hdrlen - IEEE80211_CCMP_HDR_LEN -
502                    IEEE80211_CCMP_MIC_LEN;
503         if (!rx->sta || data_len < 0)
504                 return RX_DROP_UNUSABLE;
505 
506         if (status->flag & RX_FLAG_DECRYPTED) {
507                 if (!pskb_may_pull(rx->skb, hdrlen + IEEE80211_CCMP_HDR_LEN))
508                         return RX_DROP_UNUSABLE;
509         } else {
510                 if (skb_linearize(rx->skb))
511                         return RX_DROP_UNUSABLE;
512         }
513 
514         ccmp_hdr2pn(pn, skb->data + hdrlen);
515 
516         queue = rx->security_idx;
517 
518         if (memcmp(pn, key->u.ccmp.rx_pn[queue], IEEE80211_CCMP_PN_LEN) <= 0) {
519                 key->u.ccmp.replays++;
520                 return RX_DROP_UNUSABLE;
521         }
522 
523         if (!(status->flag & RX_FLAG_DECRYPTED)) {
524                 u8 aad[2 * AES_BLOCK_SIZE];
525                 u8 b_0[AES_BLOCK_SIZE];
526                 /* hardware didn't decrypt/verify MIC */
527                 ccmp_special_blocks(skb, pn, b_0, aad, 1);
528 
529                 if (ieee80211_aes_ccm_decrypt(
530                             key->u.ccmp.tfm, b_0, aad,
531                             skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN,
532                             data_len,
533                             skb->data + skb->len - IEEE80211_CCMP_MIC_LEN))
534                         return RX_DROP_UNUSABLE;
535         }
536 
537         memcpy(key->u.ccmp.rx_pn[queue], pn, IEEE80211_CCMP_PN_LEN);
538 
539         /* Remove CCMP header and MIC */
540         if (pskb_trim(skb, skb->len - IEEE80211_CCMP_MIC_LEN))
541                 return RX_DROP_UNUSABLE;
542         memmove(skb->data + IEEE80211_CCMP_HDR_LEN, skb->data, hdrlen);
543         skb_pull(skb, IEEE80211_CCMP_HDR_LEN);
544 
545         return RX_CONTINUE;
546 }
547 
548 
549 static void bip_aad(struct sk_buff *skb, u8 *aad)
550 {
551         __le16 mask_fc;
552         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
553 
554         /* BIP AAD: FC(masked) || A1 || A2 || A3 */
555 
556         /* FC type/subtype */
557         /* Mask FC Retry, PwrMgt, MoreData flags to zero */
558         mask_fc = hdr->frame_control;
559         mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | IEEE80211_FCTL_PM |
560                                 IEEE80211_FCTL_MOREDATA);
561         put_unaligned(mask_fc, (__le16 *) &aad[0]);
562         /* A1 || A2 || A3 */
563         memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN);
564 }
565 
566 
567 static inline void bip_ipn_set64(u8 *d, u64 pn)
568 {
569         *d++ = pn;
570         *d++ = pn >> 8;
571         *d++ = pn >> 16;
572         *d++ = pn >> 24;
573         *d++ = pn >> 32;
574         *d = pn >> 40;
575 }
576 
577 static inline void bip_ipn_swap(u8 *d, const u8 *s)
578 {
579         *d++ = s[5];
580         *d++ = s[4];
581         *d++ = s[3];
582         *d++ = s[2];
583         *d++ = s[1];
584         *d = s[0];
585 }
586 
587 
588 ieee80211_tx_result
589 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
590 {
591         struct sk_buff *skb;
592         struct ieee80211_tx_info *info;
593         struct ieee80211_key *key = tx->key;
594         struct ieee80211_mmie *mmie;
595         u8 aad[20];
596         u64 pn64;
597 
598         if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
599                 return TX_DROP;
600 
601         skb = skb_peek(&tx->skbs);
602 
603         info = IEEE80211_SKB_CB(skb);
604 
605         if (info->control.hw_key)
606                 return TX_CONTINUE;
607 
608         if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
609                 return TX_DROP;
610 
611         mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
612         mmie->element_id = WLAN_EID_MMIE;
613         mmie->length = sizeof(*mmie) - 2;
614         mmie->key_id = cpu_to_le16(key->conf.keyidx);
615 
616         /* PN = PN + 1 */
617         pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);
618 
619         bip_ipn_set64(mmie->sequence_number, pn64);
620 
621         bip_aad(skb, aad);
622 
623         /*
624          * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
625          */
626         ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
627                            skb->data + 24, skb->len - 24, mmie->mic);
628 
629         return TX_CONTINUE;
630 }
631 
632 
633 ieee80211_rx_result
634 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
635 {
636         struct sk_buff *skb = rx->skb;
637         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
638         struct ieee80211_key *key = rx->key;
639         struct ieee80211_mmie *mmie;
640         u8 aad[20], mic[8], ipn[6];
641         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
642 
643         if (!ieee80211_is_mgmt(hdr->frame_control))
644                 return RX_CONTINUE;
645 
646         /* management frames are already linear */
647 
648         if (skb->len < 24 + sizeof(*mmie))
649                 return RX_DROP_UNUSABLE;
650 
651         mmie = (struct ieee80211_mmie *)
652                 (skb->data + skb->len - sizeof(*mmie));
653         if (mmie->element_id != WLAN_EID_MMIE ||
654             mmie->length != sizeof(*mmie) - 2)
655                 return RX_DROP_UNUSABLE; /* Invalid MMIE */
656 
657         bip_ipn_swap(ipn, mmie->sequence_number);
658 
659         if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
660                 key->u.aes_cmac.replays++;
661                 return RX_DROP_UNUSABLE;
662         }
663 
664         if (!(status->flag & RX_FLAG_DECRYPTED)) {
665                 /* hardware didn't decrypt/verify MIC */
666                 bip_aad(skb, aad);
667                 ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
668                                    skb->data + 24, skb->len - 24, mic);
669                 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
670                         key->u.aes_cmac.icverrors++;
671                         return RX_DROP_UNUSABLE;
672                 }
673         }
674 
675         memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
676 
677         /* Remove MMIE */
678         skb_trim(skb, skb->len - sizeof(*mmie));
679 
680         return RX_CONTINUE;
681 }
682 
683 ieee80211_tx_result
684 ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
685 {
686         struct sk_buff *skb;
687         struct ieee80211_tx_info *info = NULL;
688 
689         skb_queue_walk(&tx->skbs, skb) {
690                 info  = IEEE80211_SKB_CB(skb);
691 
692                 /* handle hw-only algorithm */
693                 if (!info->control.hw_key)
694                         return TX_DROP;
695         }
696 
697         ieee80211_tx_set_protected(tx);
698 
699         return TX_CONTINUE;
700 }
701 

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