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 #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 += TKIP_ICV_LEN;
  66
  67         if (WARN_ON(skb_tailroom(skb) < tail ||
  68                     skb_headroom(skb) < 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;
 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         /*
 165          * In some cases the key can be unset - e.g. a multicast packet, in
 166          * a driver that supports HW encryption. Send up the key idx only if
 167          * the key is set.
 168          */
 169         mac80211_ev_michael_mic_failure(rx->sdata,
 170                                         rx->key ? rx->key->conf.keyidx : -1,
 171                                         (void *) skb->data, NULL, GFP_ATOMIC);
 172         return RX_DROP_UNUSABLE;
 173 }
 174
 175
 176 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 177 {
 178         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 179         struct ieee80211_key *key = tx->key;
 180         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 181         unsigned long flags;
 182         unsigned int hdrlen;
 183         int len, tail;
 184         u8 *pos;
 185
 186         if (info->control.hw_key &&
 187             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
 188             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
 189                 /* hwaccel - with no need for software-generated IV */
 190                 return 0;
 191         }
 192
 193         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 194         len = skb->len - hdrlen;
 195
 196         if (info->control.hw_key)
 197                 tail = 0;
 198         else
 199                 tail = TKIP_ICV_LEN;
 200
 201         if (WARN_ON(skb_tailroom(skb) < tail ||
 202                     skb_headroom(skb) < TKIP_IV_LEN))
 203                 return -1;
 204
 205         pos = skb_push(skb, TKIP_IV_LEN);
 206         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 207         skb_set_network_header(skb, skb_network_offset(skb) + TKIP_IV_LEN);
 208         pos += hdrlen;
 209
 210         /* the HW only needs room for the IV, but not the actual IV */
 211         if (info->control.hw_key &&
 212             (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
 213                 return 0;
 214
 215         /* Increase IV for the frame */
 216         spin_lock_irqsave(&key->u.tkip.txlock, flags);
 217         key->u.tkip.tx.iv16++;
 218         if (key->u.tkip.tx.iv16 == 0)
 219                 key->u.tkip.tx.iv32++;
 220         pos = ieee80211_tkip_add_iv(pos, key);
 221         spin_unlock_irqrestore(&key->u.tkip.txlock, flags);
 222
 223         /* hwaccel - with software IV */
 224         if (info->control.hw_key)
 225                 return 0;
 226
 227         /* Add room for ICV */
 228         skb_put(skb, TKIP_ICV_LEN);
 229
 230         return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 231                                            key, skb, pos, len);
 232 }
 233
 234
 235 ieee80211_tx_result
 236 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 237 {
 238         struct sk_buff *skb;
 239
 240         ieee80211_tx_set_protected(tx);
 241
 242         skb_queue_walk(&tx->skbs, skb) {
 243                 if (tkip_encrypt_skb(tx, skb) < 0)
 244                         return TX_DROP;
 245         }
 246
 247         return TX_CONTINUE;
 248 }
 249
 250
 251 ieee80211_rx_result
 252 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 253 {
 254         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 255         int hdrlen, res, hwaccel = 0;
 256         struct ieee80211_key *key = rx->key;
 257         struct sk_buff *skb = rx->skb;
 258         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 259
 260         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 261
 262         if (!ieee80211_is_data(hdr->frame_control))
 263                 return RX_CONTINUE;
 264
 265         if (!rx->sta || skb->len - hdrlen < 12)
 266                 return RX_DROP_UNUSABLE;
 267
 268         /* it may be possible to optimize this a bit more */
 269         if (skb_linearize(rx->skb))
 270                 return RX_DROP_UNUSABLE;
 271         hdr = (void *)skb->data;
 272
 273         /*
 274          * Let TKIP code verify IV, but skip decryption.
 275          * In the case where hardware checks the IV as well,
 276          * we don't even get here, see ieee80211_rx_h_decrypt()
 277          */
 278         if (status->flag & RX_FLAG_DECRYPTED)
 279                 hwaccel = 1;
 280
 281         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 282                                           key, skb->data + hdrlen,
 283                                           skb->len - hdrlen, rx->sta->sta.addr,
 284                                           hdr->addr1, hwaccel, rx->security_idx,
 285                                           &rx->tkip_iv32,
 286                                           &rx->tkip_iv16);
 287         if (res != TKIP_DECRYPT_OK)
 288                 return RX_DROP_UNUSABLE;
 289
 290         /* Trim ICV */
 291         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 292
 293         /* Remove IV */
 294         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 295         skb_pull(skb, TKIP_IV_LEN);
 296
 297         return RX_CONTINUE;
 298 }
 299
 300
 301 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
 302                                 int encrypted)
 303 {
 304         __le16 mask_fc;
 305         int a4_included, mgmt;
 306         u8 qos_tid;
 307         u8 *b_0, *aad;
 308         u16 data_len, len_a;
 309         unsigned int hdrlen;
 310         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 311
 312         memset(scratch, 0, 6 * AES_BLOCK_SIZE);
 313
 314         b_0 = scratch + 3 * AES_BLOCK_SIZE;
 315         aad = scratch + 4 * AES_BLOCK_SIZE;
 316
 317         /*
 318          * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
 319          * Retry, PwrMgt, MoreData; set Protected
 320          */
 321         mgmt = ieee80211_is_mgmt(hdr->frame_control);
 322         mask_fc = hdr->frame_control;
 323         mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
 324                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 325         if (!mgmt)
 326                 mask_fc &= ~cpu_to_le16(0x0070);
 327         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 328
 329         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 330         len_a = hdrlen - 2;
 331         a4_included = ieee80211_has_a4(hdr->frame_control);
 332
 333         if (ieee80211_is_data_qos(hdr->frame_control))
 334                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 335         else
 336                 qos_tid = 0;
 337
 338         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 339         if (encrypted)
 340                 data_len -= CCMP_MIC_LEN;
 341
 342         /* First block, b_0 */
 343         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 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, CCMP_PN_LEN);
 350         /* l(m) */
 351         put_unaligned_be16(data_len, &b_0[14]);
 352
 353         /* AAD (extra authenticate-only data) / masked 802.11 header
 354          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 355         put_unaligned_be16(len_a, &aad[0]);
 356         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 357         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 358
 359         /* Mask Seq#, leave Frag# */
 360         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 361         aad[23] = 0;
 362
 363         if (a4_included) {
 364                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 365                 aad[30] = qos_tid;
 366                 aad[31] = 0;
 367         } else {
 368                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 369                 aad[24] = qos_tid;
 370         }
 371 }
 372
 373
 374 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 375 {
 376         hdr[0] = pn[5];
 377         hdr[1] = pn[4];
 378         hdr[2] = 0;
 379         hdr[3] = 0x20 | (key_id << 6);
 380         hdr[4] = pn[3];
 381         hdr[5] = pn[2];
 382         hdr[6] = pn[1];
 383         hdr[7] = pn[0];
 384 }
 385
 386
 387 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
 388 {
 389         pn[0] = hdr[7];
 390         pn[1] = hdr[6];
 391         pn[2] = hdr[5];
 392         pn[3] = hdr[4];
 393         pn[4] = hdr[1];
 394         pn[5] = hdr[0];
 395 }
 396
 397
 398 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 399 {
 400         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 401         struct ieee80211_key *key = tx->key;
 402         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 403         int hdrlen, len, tail;
 404         u8 *pos;
 405         u8 pn[6];
 406         u64 pn64;
 407         u8 scratch[6 * AES_BLOCK_SIZE];
 408
 409         if (info->control.hw_key &&
 410             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
 411             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
 412                 /*
 413                  * hwaccel has no need for preallocated room for CCMP
 414                  * header or MIC fields
 415                  */
 416                 return 0;
 417         }
 418
 419         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 420         len = skb->len - hdrlen;
 421
 422         if (info->control.hw_key)
 423                 tail = 0;
 424         else
 425                 tail = CCMP_MIC_LEN;
 426
 427         if (WARN_ON(skb_tailroom(skb) < tail ||
 428                     skb_headroom(skb) < CCMP_HDR_LEN))
 429                 return -1;
 430
 431         pos = skb_push(skb, CCMP_HDR_LEN);
 432         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 433         skb_set_network_header(skb, skb_network_offset(skb) + 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 += CCMP_HDR_LEN;
 459         ccmp_special_blocks(skb, pn, scratch, 0);
 460         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
 461                                   pos, skb_put(skb, 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[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 - CCMP_HDR_LEN - CCMP_MIC_LEN;
 502         if (!rx->sta || data_len < 0)
 503                 return RX_DROP_UNUSABLE;
 504
 505         if (status->flag & RX_FLAG_DECRYPTED) {
 506                 if (!pskb_may_pull(rx->skb, hdrlen + CCMP_HDR_LEN))
 507                         return RX_DROP_UNUSABLE;
 508         } else {
 509                 if (skb_linearize(rx->skb))
 510                         return RX_DROP_UNUSABLE;
 511         }
 512
 513         ccmp_hdr2pn(pn, skb->data + hdrlen);
 514
 515         queue = rx->security_idx;
 516
 517         if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) {
 518                 key->u.ccmp.replays++;
 519                 return RX_DROP_UNUSABLE;
 520         }
 521
 522         if (!(status->flag & RX_FLAG_DECRYPTED)) {
 523                 u8 scratch[6 * AES_BLOCK_SIZE];
 524                 /* hardware didn't decrypt/verify MIC */
 525                 ccmp_special_blocks(skb, pn, scratch, 1);
 526
 527                 if (ieee80211_aes_ccm_decrypt(
 528                             key->u.ccmp.tfm, scratch,
 529                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 530                             skb->data + skb->len - CCMP_MIC_LEN,
 531                             skb->data + hdrlen + CCMP_HDR_LEN))
 532                         return RX_DROP_UNUSABLE;
 533         }
 534
 535         memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);
 536
 537         /* Remove CCMP header and MIC */
 538         if (pskb_trim(skb, skb->len - CCMP_MIC_LEN))
 539                 return RX_DROP_UNUSABLE;
 540         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 541         skb_pull(skb, CCMP_HDR_LEN);
 542
 543         return RX_CONTINUE;
 544 }
 545
 546
 547 static void bip_aad(struct sk_buff *skb, u8 *aad)
 548 {
 549         __le16 mask_fc;
 550         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 551
 552         /* BIP AAD: FC(masked) || A1 || A2 || A3 */
 553
 554         /* FC type/subtype */
 555         /* Mask FC Retry, PwrMgt, MoreData flags to zero */
 556         mask_fc = hdr->frame_control;
 557         mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | IEEE80211_FCTL_PM |
 558                                 IEEE80211_FCTL_MOREDATA);
 559         put_unaligned(mask_fc, (__le16 *) &aad[0]);
 560         /* A1 || A2 || A3 */
 561         memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN);
 562 }
 563
 564
 565 static inline void bip_ipn_set64(u8 *d, u64 pn)
 566 {
 567         *d++ = pn;
 568         *d++ = pn >> 8;
 569         *d++ = pn >> 16;
 570         *d++ = pn >> 24;
 571         *d++ = pn >> 32;
 572         *d = pn >> 40;
 573 }
 574
 575 static inline void bip_ipn_swap(u8 *d, const u8 *s)
 576 {
 577         *d++ = s[5];
 578         *d++ = s[4];
 579         *d++ = s[3];
 580         *d++ = s[2];
 581         *d++ = s[1];
 582         *d = s[0];
 583 }
 584
 585
 586 ieee80211_tx_result
 587 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
 588 {
 589         struct sk_buff *skb;
 590         struct ieee80211_tx_info *info;
 591         struct ieee80211_key *key = tx->key;
 592         struct ieee80211_mmie *mmie;
 593         u8 aad[20];
 594         u64 pn64;
 595
 596         if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
 597                 return TX_DROP;
 598
 599         skb = skb_peek(&tx->skbs);
 600
 601         info = IEEE80211_SKB_CB(skb);
 602
 603         if (info->control.hw_key)
 604                 return TX_CONTINUE;
 605
 606         if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
 607                 return TX_DROP;
 608
 609         mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
 610         mmie->element_id = WLAN_EID_MMIE;
 611         mmie->length = sizeof(*mmie) - 2;
 612         mmie->key_id = cpu_to_le16(key->conf.keyidx);
 613
 614         /* PN = PN + 1 */
 615         pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);
 616
 617         bip_ipn_set64(mmie->sequence_number, pn64);
 618
 619         bip_aad(skb, aad);
 620
 621         /*
 622          * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
 623          */
 624         ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
 625                            skb->data + 24, skb->len - 24, mmie->mic);
 626
 627         return TX_CONTINUE;
 628 }
 629
 630
 631 ieee80211_rx_result
 632 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
 633 {
 634         struct sk_buff *skb = rx->skb;
 635         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 636         struct ieee80211_key *key = rx->key;
 637         struct ieee80211_mmie *mmie;
 638         u8 aad[20], mic[8], ipn[6];
 639         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 640
 641         if (!ieee80211_is_mgmt(hdr->frame_control))
 642                 return RX_CONTINUE;
 643
 644         /* management frames are already linear */
 645
 646         if (skb->len < 24 + sizeof(*mmie))
 647                 return RX_DROP_UNUSABLE;
 648
 649         mmie = (struct ieee80211_mmie *)
 650                 (skb->data + skb->len - sizeof(*mmie));
 651         if (mmie->element_id != WLAN_EID_MMIE ||
 652             mmie->length != sizeof(*mmie) - 2)
 653                 return RX_DROP_UNUSABLE; /* Invalid MMIE */
 654
 655         bip_ipn_swap(ipn, mmie->sequence_number);
 656
 657         if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
 658                 key->u.aes_cmac.replays++;
 659                 return RX_DROP_UNUSABLE;
 660         }
 661
 662         if (!(status->flag & RX_FLAG_DECRYPTED)) {
 663                 /* hardware didn't decrypt/verify MIC */
 664                 bip_aad(skb, aad);
 665                 ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
 666                                    skb->data + 24, skb->len - 24, mic);
 667                 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
 668                         key->u.aes_cmac.icverrors++;
 669                         return RX_DROP_UNUSABLE;
 670                 }
 671         }
 672
 673         memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
 674
 675         /* Remove MMIE */
 676         skb_trim(skb, skb->len - sizeof(*mmie));
 677
 678         return RX_CONTINUE;
 679 }
 680
 681 ieee80211_tx_result
 682 ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
 683 {
 684         struct sk_buff *skb;
 685         struct ieee80211_tx_info *info = NULL;
 686
 687         skb_queue_walk(&tx->skbs, skb) {
 688                 info  = IEEE80211_SKB_CB(skb);
 689
 690                 /* handle hw-only algorithm */
 691                 if (!info->control.hw_key)
 692                         return TX_DROP;
 693         }
 694
 695         ieee80211_tx_set_protected(tx);
 696
 697         return TX_CONTINUE;
 698 }