release/src-rt-6.x.4708/linux/linux-2.6.36/net/mac80211/wpa.c

   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
  19 #include "ieee80211_i.h"
  20 #include "michael.h"
  21 #include "tkip.h"
  22 #include "aes_ccm.h"
  23 #include "aes_cmac.h"
  24 #include "wpa.h"
  25
  26 ieee80211_tx_result
  27 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
  28 {
  29         u8 *data, *key, *mic, key_offset;
  30         size_t data_len;
  31         unsigned int hdrlen;
  32         struct ieee80211_hdr *hdr;
  33         struct sk_buff *skb = tx->skb;
  34         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
  35         int authenticator;
  36         int tail;
  37
  38         hdr = (struct ieee80211_hdr *)skb->data;
  39         if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
  40             !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 (info->control.hw_key &&
  51             !(tx->flags & IEEE80211_TX_FRAGMENTED) &&
  52             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
  53                 /* hwaccel - with no need for SW-generated MMIC */
  54                 return TX_CONTINUE;
  55         }
  56
  57         tail = MICHAEL_MIC_LEN;
  58         if (!info->control.hw_key)
  59                 tail += TKIP_ICV_LEN;
  60
  61         if (WARN_ON(skb_tailroom(skb) < tail ||
  62                     skb_headroom(skb) < TKIP_IV_LEN))
  63                 return TX_DROP;
  64
  65         authenticator = 1;
  66         key_offset = authenticator ?
  67                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
  68                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
  69         key = &tx->key->conf.key[key_offset];
  70         mic = skb_put(skb, MICHAEL_MIC_LEN);
  71         michael_mic(key, hdr, data, data_len, mic);
  72
  73         return TX_CONTINUE;
  74 }
  75
  76
  77 ieee80211_rx_result
  78 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
  79 {
  80         u8 *data, *key = NULL, key_offset;
  81         size_t data_len;
  82         unsigned int hdrlen;
  83         u8 mic[MICHAEL_MIC_LEN];
  84         struct sk_buff *skb = rx->skb;
  85         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
  86         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
  87         int authenticator = 1, wpa_test = 0;
  88
  89         /* No way to verify the MIC if the hardware stripped it */
  90         if (status->flag & RX_FLAG_MMIC_STRIPPED)
  91                 return RX_CONTINUE;
  92
  93         if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
  94             !ieee80211_has_protected(hdr->frame_control) ||
  95             !ieee80211_is_data_present(hdr->frame_control))
  96                 return RX_CONTINUE;
  97
  98         hdrlen = ieee80211_hdrlen(hdr->frame_control);
  99         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
 100                 return RX_DROP_UNUSABLE;
 101
 102         data = skb->data + hdrlen;
 103         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
 104
 105         authenticator = 1;
 106         key_offset = authenticator ?
 107                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
 108                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
 109         key = &rx->key->conf.key[key_offset];
 110         michael_mic(key, hdr, data, data_len, mic);
 111         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
 112                 if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 113                         return RX_DROP_UNUSABLE;
 114
 115                 mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
 116                                                 (void *) skb->data, NULL,
 117                                                 GFP_ATOMIC);
 118                 return RX_DROP_UNUSABLE;
 119         }
 120
 121         /* remove Michael MIC from payload */
 122         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
 123
 124         /* update IV in key information to be able to detect replays */
 125         rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
 126         rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
 127
 128         return RX_CONTINUE;
 129 }
 130
 131
 132 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 133 {
 134         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 135         struct ieee80211_key *key = tx->key;
 136         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 137         unsigned int hdrlen;
 138         int len, tail;
 139         u8 *pos;
 140
 141         if (info->control.hw_key &&
 142             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 143                 /* hwaccel - with no need for software-generated IV */
 144                 return 0;
 145         }
 146
 147         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 148         len = skb->len - hdrlen;
 149
 150         if (info->control.hw_key)
 151                 tail = 0;
 152         else
 153                 tail = TKIP_ICV_LEN;
 154
 155         if (WARN_ON(skb_tailroom(skb) < tail ||
 156                     skb_headroom(skb) < TKIP_IV_LEN))
 157                 return -1;
 158
 159         pos = skb_push(skb, TKIP_IV_LEN);
 160         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 161         pos += hdrlen;
 162
 163         /* Increase IV for the frame */
 164         key->u.tkip.tx.iv16++;
 165         if (key->u.tkip.tx.iv16 == 0)
 166                 key->u.tkip.tx.iv32++;
 167
 168         pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 169
 170         /* hwaccel - with software IV */
 171         if (info->control.hw_key)
 172                 return 0;
 173
 174         /* Add room for ICV */
 175         skb_put(skb, TKIP_ICV_LEN);
 176
 177         hdr = (struct ieee80211_hdr *) skb->data;
 178         return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 179                                            key, pos, len, hdr->addr2);
 180 }
 181
 182
 183 ieee80211_tx_result
 184 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 185 {
 186         struct sk_buff *skb = tx->skb;
 187
 188         ieee80211_tx_set_protected(tx);
 189
 190         do {
 191                 if (tkip_encrypt_skb(tx, skb) < 0)
 192                         return TX_DROP;
 193         } while ((skb = skb->next));
 194
 195         return TX_CONTINUE;
 196 }
 197
 198
 199 ieee80211_rx_result
 200 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 201 {
 202         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 203         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 204         struct ieee80211_key *key = rx->key;
 205         struct sk_buff *skb = rx->skb;
 206         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 207
 208         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 209
 210         if (!ieee80211_is_data(hdr->frame_control))
 211                 return RX_CONTINUE;
 212
 213         if (!rx->sta || skb->len - hdrlen < 12)
 214                 return RX_DROP_UNUSABLE;
 215
 216         if (status->flag & RX_FLAG_DECRYPTED) {
 217                 if (status->flag & RX_FLAG_IV_STRIPPED) {
 218                         /*
 219                          * Hardware took care of all processing, including
 220                          * replay protection, and stripped the ICV/IV so
 221                          * we cannot do any checks here.
 222                          */
 223                         return RX_CONTINUE;
 224                 }
 225
 226                 /* let TKIP code verify IV, but skip decryption */
 227                 hwaccel = 1;
 228         }
 229
 230         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 231                                           key, skb->data + hdrlen,
 232                                           skb->len - hdrlen, rx->sta->sta.addr,
 233                                           hdr->addr1, hwaccel, rx->queue,
 234                                           &rx->tkip_iv32,
 235                                           &rx->tkip_iv16);
 236         if (res != TKIP_DECRYPT_OK || wpa_test)
 237                 return RX_DROP_UNUSABLE;
 238
 239         /* Trim ICV */
 240         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 241
 242         /* Remove IV */
 243         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 244         skb_pull(skb, TKIP_IV_LEN);
 245
 246         return RX_CONTINUE;
 247 }
 248
 249
 250 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
 251                                 int encrypted)
 252 {
 253         __le16 mask_fc;
 254         int a4_included, mgmt;
 255         u8 qos_tid;
 256         u8 *b_0, *aad;
 257         u16 data_len, len_a;
 258         unsigned int hdrlen;
 259         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 260
 261         b_0 = scratch + 3 * AES_BLOCK_LEN;
 262         aad = scratch + 4 * AES_BLOCK_LEN;
 263
 264         /*
 265          * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
 266          * Retry, PwrMgt, MoreData; set Protected
 267          */
 268         mgmt = ieee80211_is_mgmt(hdr->frame_control);
 269         mask_fc = hdr->frame_control;
 270         mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
 271                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 272         if (!mgmt)
 273                 mask_fc &= ~cpu_to_le16(0x0070);
 274         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 275
 276         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 277         len_a = hdrlen - 2;
 278         a4_included = ieee80211_has_a4(hdr->frame_control);
 279
 280         if (ieee80211_is_data_qos(hdr->frame_control))
 281                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 282         else
 283                 qos_tid = 0;
 284
 285         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 286         if (encrypted)
 287                 data_len -= CCMP_MIC_LEN;
 288
 289         /* First block, b_0 */
 290         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 291         /* Nonce: Nonce Flags | A2 | PN
 292          * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
 293          */
 294         b_0[1] = qos_tid | (mgmt << 4);
 295         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
 296         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 297         /* l(m) */
 298         put_unaligned_be16(data_len, &b_0[14]);
 299
 300         /* AAD (extra authenticate-only data) / masked 802.11 header
 301          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 302         put_unaligned_be16(len_a, &aad[0]);
 303         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 304         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 305
 306         /* Mask Seq#, leave Frag# */
 307         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 308         aad[23] = 0;
 309
 310         if (a4_included) {
 311                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 312                 aad[30] = qos_tid;
 313                 aad[31] = 0;
 314         } else {
 315                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 316                 aad[24] = qos_tid;
 317         }
 318 }
 319
 320
 321 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 322 {
 323         hdr[0] = pn[5];
 324         hdr[1] = pn[4];
 325         hdr[2] = 0;
 326         hdr[3] = 0x20 | (key_id << 6);
 327         hdr[4] = pn[3];
 328         hdr[5] = pn[2];
 329         hdr[6] = pn[1];
 330         hdr[7] = pn[0];
 331 }
 332
 333
 334 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
 335 {
 336         pn[0] = hdr[7];
 337         pn[1] = hdr[6];
 338         pn[2] = hdr[5];
 339         pn[3] = hdr[4];
 340         pn[4] = hdr[1];
 341         pn[5] = hdr[0];
 342 }
 343
 344
 345 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 346 {
 347         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 348         struct ieee80211_key *key = tx->key;
 349         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 350         int hdrlen, len, tail;
 351         u8 *pos, *pn;
 352         int i;
 353
 354         if (info->control.hw_key &&
 355             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 356                 /*
 357                  * hwaccel has no need for preallocated room for CCMP
 358                  * header or MIC fields
 359                  */
 360                 return 0;
 361         }
 362
 363         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 364         len = skb->len - hdrlen;
 365
 366         if (info->control.hw_key)
 367                 tail = 0;
 368         else
 369                 tail = CCMP_MIC_LEN;
 370
 371         if (WARN_ON(skb_tailroom(skb) < tail ||
 372                     skb_headroom(skb) < CCMP_HDR_LEN))
 373                 return -1;
 374
 375         pos = skb_push(skb, CCMP_HDR_LEN);
 376         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 377         hdr = (struct ieee80211_hdr *) pos;
 378         pos += hdrlen;
 379
 380         /* PN = PN + 1 */
 381         pn = key->u.ccmp.tx_pn;
 382
 383         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 384                 pn[i]++;
 385                 if (pn[i])
 386                         break;
 387         }
 388
 389         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 390
 391         /* hwaccel - with software CCMP header */
 392         if (info->control.hw_key)
 393                 return 0;
 394
 395         pos += CCMP_HDR_LEN;
 396         ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
 397         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
 398                                   pos, skb_put(skb, CCMP_MIC_LEN));
 399
 400         return 0;
 401 }
 402
 403
 404 ieee80211_tx_result
 405 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 406 {
 407         struct sk_buff *skb = tx->skb;
 408
 409         ieee80211_tx_set_protected(tx);
 410
 411         do {
 412                 if (ccmp_encrypt_skb(tx, skb) < 0)
 413                         return TX_DROP;
 414         } while ((skb = skb->next));
 415
 416         return TX_CONTINUE;
 417 }
 418
 419
 420 ieee80211_rx_result
 421 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 422 {
 423         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
 424         int hdrlen;
 425         struct ieee80211_key *key = rx->key;
 426         struct sk_buff *skb = rx->skb;
 427         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 428         u8 pn[CCMP_PN_LEN];
 429         int data_len;
 430         int queue;
 431
 432         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 433
 434         if (!ieee80211_is_data(hdr->frame_control) &&
 435             !ieee80211_is_robust_mgmt_frame(hdr))
 436                 return RX_CONTINUE;
 437
 438         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 439         if (!rx->sta || data_len < 0)
 440                 return RX_DROP_UNUSABLE;
 441
 442         if ((status->flag & RX_FLAG_DECRYPTED) &&
 443             (status->flag & RX_FLAG_IV_STRIPPED))
 444                 return RX_CONTINUE;
 445
 446         ccmp_hdr2pn(pn, skb->data + hdrlen);
 447
 448         queue = ieee80211_is_mgmt(hdr->frame_control) ?
 449                 NUM_RX_DATA_QUEUES : rx->queue;
 450
 451         if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) {
 452                 key->u.ccmp.replays++;
 453                 return RX_DROP_UNUSABLE;
 454         }
 455
 456         if (!(status->flag & RX_FLAG_DECRYPTED)) {
 457                 /* hardware didn't decrypt/verify MIC */
 458                 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
 459
 460                 if (ieee80211_aes_ccm_decrypt(
 461                             key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
 462                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 463                             skb->data + skb->len - CCMP_MIC_LEN,
 464                             skb->data + hdrlen + CCMP_HDR_LEN))
 465                         return RX_DROP_UNUSABLE;
 466         }
 467
 468         memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);
 469
 470         /* Remove CCMP header and MIC */
 471         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 472         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 473         skb_pull(skb, CCMP_HDR_LEN);
 474
 475         return RX_CONTINUE;
 476 }
 477
 478
 479 static void bip_aad(struct sk_buff *skb, u8 *aad)
 480 {
 481         /* BIP AAD: FC(masked) || A1 || A2 || A3 */
 482
 483         /* FC type/subtype */
 484         aad[0] = skb->data[0];
 485         /* Mask FC Retry, PwrMgt, MoreData flags to zero */
 486         aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6));
 487         /* A1 || A2 || A3 */
 488         memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN);
 489 }
 490
 491
 492 static inline void bip_ipn_swap(u8 *d, const u8 *s)
 493 {
 494         *d++ = s[5];
 495         *d++ = s[4];
 496         *d++ = s[3];
 497         *d++ = s[2];
 498         *d++ = s[1];
 499         *d = s[0];
 500 }
 501
 502
 503 ieee80211_tx_result
 504 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
 505 {
 506         struct sk_buff *skb = tx->skb;
 507         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 508         struct ieee80211_key *key = tx->key;
 509         struct ieee80211_mmie *mmie;
 510         u8 *pn, aad[20];
 511         int i;
 512
 513         if (info->control.hw_key)
 514                 return 0;
 515
 516         if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
 517                 return TX_DROP;
 518
 519         mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
 520         mmie->element_id = WLAN_EID_MMIE;
 521         mmie->length = sizeof(*mmie) - 2;
 522         mmie->key_id = cpu_to_le16(key->conf.keyidx);
 523
 524         /* PN = PN + 1 */
 525         pn = key->u.aes_cmac.tx_pn;
 526
 527         for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) {
 528                 pn[i]++;
 529                 if (pn[i])
 530                         break;
 531         }
 532         bip_ipn_swap(mmie->sequence_number, pn);
 533
 534         bip_aad(skb, aad);
 535
 536         /*
 537          * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
 538          */
 539         ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf,
 540                            aad, skb->data + 24, skb->len - 24, mmie->mic);
 541
 542         return TX_CONTINUE;
 543 }
 544
 545
 546 ieee80211_rx_result
 547 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
 548 {
 549         struct sk_buff *skb = rx->skb;
 550         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 551         struct ieee80211_key *key = rx->key;
 552         struct ieee80211_mmie *mmie;
 553         u8 aad[20], mic[8], ipn[6];
 554         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 555
 556         if (!ieee80211_is_mgmt(hdr->frame_control))
 557                 return RX_CONTINUE;
 558
 559         if ((status->flag & RX_FLAG_DECRYPTED) &&
 560             (status->flag & RX_FLAG_IV_STRIPPED))
 561                 return RX_CONTINUE;
 562
 563         if (skb->len < 24 + sizeof(*mmie))
 564                 return RX_DROP_UNUSABLE;
 565
 566         mmie = (struct ieee80211_mmie *)
 567                 (skb->data + skb->len - sizeof(*mmie));
 568         if (mmie->element_id != WLAN_EID_MMIE ||
 569             mmie->length != sizeof(*mmie) - 2)
 570                 return RX_DROP_UNUSABLE; /* Invalid MMIE */
 571
 572         bip_ipn_swap(ipn, mmie->sequence_number);
 573
 574         if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
 575                 key->u.aes_cmac.replays++;
 576                 return RX_DROP_UNUSABLE;
 577         }
 578
 579         if (!(status->flag & RX_FLAG_DECRYPTED)) {
 580                 /* hardware didn't decrypt/verify MIC */
 581                 bip_aad(skb, aad);
 582                 ieee80211_aes_cmac(key->u.aes_cmac.tfm,
 583                                    key->u.aes_cmac.rx_crypto_buf, aad,
 584                                    skb->data + 24, skb->len - 24, mic);
 585                 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
 586                         key->u.aes_cmac.icverrors++;
 587                         return RX_DROP_UNUSABLE;
 588                 }
 589         }
 590
 591         memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
 592
 593         /* Remove MMIE */
 594         skb_trim(skb, skb->len - sizeof(*mmie));
 595
 596         return RX_CONTINUE;
 597 }