net/mac80211/wpa.c

   1 /*
   2  * Copyright 2002-2004, Instant802 Networks, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/netdevice.h>
  10 #include <linux/types.h>
  11 #include <linux/slab.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/compiler.h>
  14 #include <linux/ieee80211.h>
  15 #include <asm/unaligned.h>
  16 #include <net/mac80211.h>
  17
  18 #include "ieee80211_i.h"
  19 #include "michael.h"
  20 #include "tkip.h"
  21 #include "aes_ccm.h"
  22 #include "wpa.h"
  23
  24 ieee80211_tx_result
  25 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
  26 {
  27         u8 *data, *key, *mic, key_offset;
  28         size_t data_len;
  29         unsigned int hdrlen;
  30         struct ieee80211_hdr *hdr;
  31         u16 fc;
  32         struct sk_buff *skb = tx->skb;
  33         int authenticator;
  34         int wpa_test = 0;
  35         int tail;
  36
  37         fc = tx->fc;
  38
  39         if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
  40             !WLAN_FC_DATA_PRESENT(fc))
  41                 return TX_CONTINUE;
  42
  43         hdr = (struct ieee80211_hdr *)skb->data;
  44         hdrlen = ieee80211_hdrlen(hdr->frame_control);
  45         if (skb->len < hdrlen)
  46                 return TX_DROP;
  47
  48         data = skb->data + hdrlen;
  49         data_len = skb->len - hdrlen;
  50
  51         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
  52             !(tx->flags & IEEE80211_TX_FRAGMENTED) &&
  53             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) &&
  54             !wpa_test) {
  55                 /* hwaccel - with no need for preallocated room for Michael MIC
  56                  */
  57                 return TX_CONTINUE;
  58         }
  59
  60         tail = MICHAEL_MIC_LEN;
  61         if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  62                 tail += TKIP_ICV_LEN;
  63
  64         if (WARN_ON(skb_tailroom(skb) < tail ||
  65                     skb_headroom(skb) < TKIP_IV_LEN))
  66                 return TX_DROP;
  67
  68 #if 0
  69         authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
  70 #else
  71         authenticator = 1;
  72 #endif
  73         /* At this point we know we're using ALG_TKIP. To get the MIC key
  74          * we now will rely on the offset from the ieee80211_key_conf::key */
  75         key_offset = authenticator ?
  76                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
  77                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
  78         key = &tx->key->conf.key[key_offset];
  79         mic = skb_put(skb, MICHAEL_MIC_LEN);
  80         michael_mic(key, hdr, data, data_len, mic);
  81
  82         return TX_CONTINUE;
  83 }
  84
  85
  86 ieee80211_rx_result
  87 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
  88 {
  89         u8 *data, *key = NULL, key_offset;
  90         size_t data_len;
  91         unsigned int hdrlen;
  92         struct ieee80211_hdr *hdr;
  93         u16 fc;
  94         u8 mic[MICHAEL_MIC_LEN];
  95         struct sk_buff *skb = rx->skb;
  96         int authenticator = 1, wpa_test = 0;
  97         DECLARE_MAC_BUF(mac);
  98
  99         fc = rx->fc;
 100
 101         /*
 102          * No way to verify the MIC if the hardware stripped it
 103          */
 104         if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
 105                 return RX_CONTINUE;
 106
 107         if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
 108             !(rx->fc & IEEE80211_FCTL_PROTECTED) || !WLAN_FC_DATA_PRESENT(fc))
 109                 return RX_CONTINUE;
 110
 111         hdr = (struct ieee80211_hdr *)skb->data;
 112         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 113         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
 114                 return RX_DROP_UNUSABLE;
 115
 116         data = skb->data + hdrlen;
 117         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
 118
 119 #if 0
 120         authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
 121 #else
 122         authenticator = 1;
 123 #endif
 124         /* At this point we know we're using ALG_TKIP. To get the MIC key
 125          * we now will rely on the offset from the ieee80211_key_conf::key */
 126         key_offset = authenticator ?
 127                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
 128                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
 129         key = &rx->key->conf.key[key_offset];
 130         michael_mic(key, hdr, data, data_len, mic);
 131         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
 132                 if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 133                         return RX_DROP_UNUSABLE;
 134
 135                 mac80211_ev_michael_mic_failure(rx->dev, rx->key->conf.keyidx,
 136                                                 (void *) skb->data);
 137                 return RX_DROP_UNUSABLE;
 138         }
 139
 140         /* remove Michael MIC from payload */
 141         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
 142
 143         /* update IV in key information to be able to detect replays */
 144         rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
 145         rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
 146
 147         return RX_CONTINUE;
 148 }
 149
 150
 151 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 152 {
 153         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 154         struct ieee80211_key *key = tx->key;
 155         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 156         unsigned int hdrlen;
 157         int len, tail;
 158         u8 *pos;
 159
 160         info->control.icv_len = TKIP_ICV_LEN;
 161         info->control.iv_len = TKIP_IV_LEN;
 162
 163         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 164             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 165                 /* hwaccel - with no need for preallocated room for IV/ICV */
 166                 info->control.hw_key = &tx->key->conf;
 167                 return 0;
 168         }
 169
 170         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 171         len = skb->len - hdrlen;
 172
 173         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 174                 tail = 0;
 175         else
 176                 tail = TKIP_ICV_LEN;
 177
 178         if (WARN_ON(skb_tailroom(skb) < tail ||
 179                     skb_headroom(skb) < TKIP_IV_LEN))
 180                 return -1;
 181
 182         pos = skb_push(skb, TKIP_IV_LEN);
 183         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 184         pos += hdrlen;
 185
 186         /* Increase IV for the frame */
 187         key->u.tkip.tx.iv16++;
 188         if (key->u.tkip.tx.iv16 == 0)
 189                 key->u.tkip.tx.iv32++;
 190
 191         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 192                 /* hwaccel - with preallocated room for IV */
 193                 ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 194
 195                 info->control.hw_key = &tx->key->conf;
 196                 return 0;
 197         }
 198
 199         /* Add room for ICV */
 200         skb_put(skb, TKIP_ICV_LEN);
 201
 202         hdr = (struct ieee80211_hdr *) skb->data;
 203         ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 204                                     key, pos, len, hdr->addr2);
 205         return 0;
 206 }
 207
 208
 209 ieee80211_tx_result
 210 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 211 {
 212         struct sk_buff *skb = tx->skb;
 213
 214         ieee80211_tx_set_protected(tx);
 215
 216         if (tkip_encrypt_skb(tx, skb) < 0)
 217                 return TX_DROP;
 218
 219         if (tx->extra_frag) {
 220                 int i;
 221                 for (i = 0; i < tx->num_extra_frag; i++) {
 222                         if (tkip_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 223                                 return TX_DROP;
 224                 }
 225         }
 226
 227         return TX_CONTINUE;
 228 }
 229
 230
 231 ieee80211_rx_result
 232 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 233 {
 234         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 235         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 236         struct ieee80211_key *key = rx->key;
 237         struct sk_buff *skb = rx->skb;
 238         DECLARE_MAC_BUF(mac);
 239
 240         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 241
 242         if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
 243                 return RX_CONTINUE;
 244
 245         if (!rx->sta || skb->len - hdrlen < 12)
 246                 return RX_DROP_UNUSABLE;
 247
 248         if (rx->status->flag & RX_FLAG_DECRYPTED) {
 249                 if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
 250                         /*
 251                          * Hardware took care of all processing, including
 252                          * replay protection, and stripped the ICV/IV so
 253                          * we cannot do any checks here.
 254                          */
 255                         return RX_CONTINUE;
 256                 }
 257
 258                 /* let TKIP code verify IV, but skip decryption */
 259                 hwaccel = 1;
 260         }
 261
 262         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 263                                           key, skb->data + hdrlen,
 264                                           skb->len - hdrlen, rx->sta->addr,
 265                                           hdr->addr1, hwaccel, rx->queue,
 266                                           &rx->tkip_iv32,
 267                                           &rx->tkip_iv16);
 268         if (res != TKIP_DECRYPT_OK || wpa_test)
 269                 return RX_DROP_UNUSABLE;
 270
 271         /* Trim ICV */
 272         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 273
 274         /* Remove IV */
 275         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 276         skb_pull(skb, TKIP_IV_LEN);
 277
 278         return RX_CONTINUE;
 279 }
 280
 281
 282 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
 283                                 int encrypted)
 284 {
 285         __le16 mask_fc;
 286         int a4_included;
 287         u8 qos_tid;
 288         u16 data_len, len_a;
 289         unsigned int hdrlen;
 290         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 291
 292         /*
 293          * Mask FC: zero subtype b4 b5 b6
 294          * Retry, PwrMgt, MoreData; set Protected
 295          */
 296         mask_fc = hdr->frame_control;
 297         mask_fc &= ~cpu_to_le16(0x0070 | IEEE80211_FCTL_RETRY |
 298                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 299         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 300
 301         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 302         len_a = hdrlen - 2;
 303         a4_included = ieee80211_has_a4(hdr->frame_control);
 304
 305         if (ieee80211_is_data_qos(hdr->frame_control))
 306                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 307         else
 308                 qos_tid = 0;
 309
 310         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 311         if (encrypted)
 312                 data_len -= CCMP_MIC_LEN;
 313
 314         /* First block, b_0 */
 315         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 316         /* Nonce: QoS Priority | A2 | PN */
 317         b_0[1] = qos_tid;
 318         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
 319         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 320         /* l(m) */
 321         put_unaligned_be16(data_len, &b_0[14]);
 322
 323         /* AAD (extra authenticate-only data) / masked 802.11 header
 324          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 325         put_unaligned_be16(len_a, &aad[0]);
 326         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 327         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 328
 329         /* Mask Seq#, leave Frag# */
 330         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 331         aad[23] = 0;
 332
 333         if (a4_included) {
 334                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 335                 aad[30] = qos_tid;
 336                 aad[31] = 0;
 337         } else {
 338                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 339                 aad[24] = qos_tid;
 340         }
 341 }
 342
 343
 344 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 345 {
 346         hdr[0] = pn[5];
 347         hdr[1] = pn[4];
 348         hdr[2] = 0;
 349         hdr[3] = 0x20 | (key_id << 6);
 350         hdr[4] = pn[3];
 351         hdr[5] = pn[2];
 352         hdr[6] = pn[1];
 353         hdr[7] = pn[0];
 354 }
 355
 356
 357 static inline int ccmp_hdr2pn(u8 *pn, u8 *hdr)
 358 {
 359         pn[0] = hdr[7];
 360         pn[1] = hdr[6];
 361         pn[2] = hdr[5];
 362         pn[3] = hdr[4];
 363         pn[4] = hdr[1];
 364         pn[5] = hdr[0];
 365         return (hdr[3] >> 6) & 0x03;
 366 }
 367
 368
 369 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 370 {
 371         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 372         struct ieee80211_key *key = tx->key;
 373         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 374         int hdrlen, len, tail;
 375         u8 *pos, *pn, *b_0, *aad, *scratch;
 376         int i;
 377
 378         info->control.icv_len = CCMP_MIC_LEN;
 379         info->control.iv_len = CCMP_HDR_LEN;
 380
 381         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 382             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 383                 /* hwaccel - with no need for preallocated room for CCMP "
 384                  * header or MIC fields */
 385                 info->control.hw_key = &tx->key->conf;
 386                 return 0;
 387         }
 388
 389         scratch = key->u.ccmp.tx_crypto_buf;
 390         b_0 = scratch + 3 * AES_BLOCK_LEN;
 391         aad = scratch + 4 * AES_BLOCK_LEN;
 392
 393         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 394         len = skb->len - hdrlen;
 395
 396         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 397                 tail = 0;
 398         else
 399                 tail = CCMP_MIC_LEN;
 400
 401         if (WARN_ON(skb_tailroom(skb) < tail ||
 402                     skb_headroom(skb) < CCMP_HDR_LEN))
 403                 return -1;
 404
 405         pos = skb_push(skb, CCMP_HDR_LEN);
 406         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 407         hdr = (struct ieee80211_hdr *) pos;
 408         pos += hdrlen;
 409
 410         /* PN = PN + 1 */
 411         pn = key->u.ccmp.tx_pn;
 412
 413         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 414                 pn[i]++;
 415                 if (pn[i])
 416                         break;
 417         }
 418
 419         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 420
 421         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 422                 /* hwaccel - with preallocated room for CCMP header */
 423                 info->control.hw_key = &tx->key->conf;
 424                 return 0;
 425         }
 426
 427         pos += CCMP_HDR_LEN;
 428         ccmp_special_blocks(skb, pn, b_0, aad, 0);
 429         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, b_0, aad, pos, len,
 430                                   pos, skb_put(skb, CCMP_MIC_LEN));
 431
 432         return 0;
 433 }
 434
 435
 436 ieee80211_tx_result
 437 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 438 {
 439         struct sk_buff *skb = tx->skb;
 440
 441         ieee80211_tx_set_protected(tx);
 442
 443         if (ccmp_encrypt_skb(tx, skb) < 0)
 444                 return TX_DROP;
 445
 446         if (tx->extra_frag) {
 447                 int i;
 448                 for (i = 0; i < tx->num_extra_frag; i++) {
 449                         if (ccmp_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 450                                 return TX_DROP;
 451                 }
 452         }
 453
 454         return TX_CONTINUE;
 455 }
 456
 457
 458 ieee80211_rx_result
 459 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 460 {
 461         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 462         int hdrlen;
 463         struct ieee80211_key *key = rx->key;
 464         struct sk_buff *skb = rx->skb;
 465         u8 pn[CCMP_PN_LEN];
 466         int data_len;
 467         DECLARE_MAC_BUF(mac);
 468
 469         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 470
 471         if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
 472                 return RX_CONTINUE;
 473
 474         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 475         if (!rx->sta || data_len < 0)
 476                 return RX_DROP_UNUSABLE;
 477
 478         if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
 479             (rx->status->flag & RX_FLAG_IV_STRIPPED))
 480                 return RX_CONTINUE;
 481
 482         (void) ccmp_hdr2pn(pn, skb->data + hdrlen);
 483
 484         if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
 485                 key->u.ccmp.replays++;
 486                 return RX_DROP_UNUSABLE;
 487         }
 488
 489         if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
 490                 /* hardware didn't decrypt/verify MIC */
 491                 u8 *scratch, *b_0, *aad;
 492
 493                 scratch = key->u.ccmp.rx_crypto_buf;
 494                 b_0 = scratch + 3 * AES_BLOCK_LEN;
 495                 aad = scratch + 4 * AES_BLOCK_LEN;
 496
 497                 ccmp_special_blocks(skb, pn, b_0, aad, 1);
 498
 499                 if (ieee80211_aes_ccm_decrypt(
 500                             key->u.ccmp.tfm, scratch, b_0, aad,
 501                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 502                             skb->data + skb->len - CCMP_MIC_LEN,
 503                             skb->data + hdrlen + CCMP_HDR_LEN)) {
 504                         return RX_DROP_UNUSABLE;
 505                 }
 506         }
 507
 508         memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
 509
 510         /* Remove CCMP header and MIC */
 511         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 512         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 513         skb_pull(skb, CCMP_HDR_LEN);
 514
 515         return RX_CONTINUE;
 516 }