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         struct sk_buff *skb = tx->skb;
  32         int authenticator;
  33         int wpa_test = 0;
  34         int tail;
  35
  36         hdr = (struct ieee80211_hdr *)skb->data;
  37         if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
  38             !ieee80211_is_data_present(hdr->frame_control))
  39                 return TX_CONTINUE;
  40
  41         hdrlen = ieee80211_hdrlen(hdr->frame_control);
  42         if (skb->len < hdrlen)
  43                 return TX_DROP;
  44
  45         data = skb->data + hdrlen;
  46         data_len = skb->len - hdrlen;
  47
  48         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
  49             !(tx->flags & IEEE80211_TX_FRAGMENTED) &&
  50             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) &&
  51             !wpa_test) {
  52                 /* hwaccel - with no need for preallocated room for Michael MIC
  53                  */
  54                 return TX_CONTINUE;
  55         }
  56
  57         tail = MICHAEL_MIC_LEN;
  58         if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  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 #if 0
  66         authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
  67 #else
  68         authenticator = 1;
  69 #endif
  70         /* At this point we know we're using ALG_TKIP. To get the MIC key
  71          * we now will rely on the offset from the ieee80211_key_conf::key */
  72         key_offset = authenticator ?
  73                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
  74                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
  75         key = &tx->key->conf.key[key_offset];
  76         mic = skb_put(skb, MICHAEL_MIC_LEN);
  77         michael_mic(key, hdr, data, data_len, mic);
  78
  79         return TX_CONTINUE;
  80 }
  81
  82
  83 ieee80211_rx_result
  84 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
  85 {
  86         u8 *data, *key = NULL, key_offset;
  87         size_t data_len;
  88         unsigned int hdrlen;
  89         struct ieee80211_hdr *hdr;
  90         u8 mic[MICHAEL_MIC_LEN];
  91         struct sk_buff *skb = rx->skb;
  92         int authenticator = 1, wpa_test = 0;
  93         DECLARE_MAC_BUF(mac);
  94
  95         /*
  96          * No way to verify the MIC if the hardware stripped it
  97          */
  98         if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
  99                 return RX_CONTINUE;
 100
 101         hdr = (struct ieee80211_hdr *)skb->data;
 102         if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
 103             !ieee80211_has_protected(hdr->frame_control) ||
 104             !ieee80211_is_data_present(hdr->frame_control))
 105                 return RX_CONTINUE;
 106
 107         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 108         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
 109                 return RX_DROP_UNUSABLE;
 110
 111         data = skb->data + hdrlen;
 112         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
 113
 114 #if 0
 115         authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
 116 #else
 117         authenticator = 1;
 118 #endif
 119         /* At this point we know we're using ALG_TKIP. To get the MIC key
 120          * we now will rely on the offset from the ieee80211_key_conf::key */
 121         key_offset = authenticator ?
 122                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
 123                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
 124         key = &rx->key->conf.key[key_offset];
 125         michael_mic(key, hdr, data, data_len, mic);
 126         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
 127                 if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 128                         return RX_DROP_UNUSABLE;
 129
 130                 mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
 131                                                 (void *) skb->data);
 132                 return RX_DROP_UNUSABLE;
 133         }
 134
 135         /* remove Michael MIC from payload */
 136         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
 137
 138         /* update IV in key information to be able to detect replays */
 139         rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
 140         rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
 141
 142         return RX_CONTINUE;
 143 }
 144
 145
 146 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 147 {
 148         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 149         struct ieee80211_key *key = tx->key;
 150         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 151         unsigned int hdrlen;
 152         int len, tail;
 153         u8 *pos;
 154
 155         info->control.icv_len = TKIP_ICV_LEN;
 156         info->control.iv_len = TKIP_IV_LEN;
 157
 158         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 159             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 160                 /* hwaccel - with no need for preallocated room for IV/ICV */
 161                 info->control.hw_key = &tx->key->conf;
 162                 return 0;
 163         }
 164
 165         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 166         len = skb->len - hdrlen;
 167
 168         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 169                 tail = 0;
 170         else
 171                 tail = TKIP_ICV_LEN;
 172
 173         if (WARN_ON(skb_tailroom(skb) < tail ||
 174                     skb_headroom(skb) < TKIP_IV_LEN))
 175                 return -1;
 176
 177         pos = skb_push(skb, TKIP_IV_LEN);
 178         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 179         pos += hdrlen;
 180
 181         /* Increase IV for the frame */
 182         key->u.tkip.tx.iv16++;
 183         if (key->u.tkip.tx.iv16 == 0)
 184                 key->u.tkip.tx.iv32++;
 185
 186         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 187                 /* hwaccel - with preallocated room for IV */
 188                 ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 189
 190                 info->control.hw_key = &tx->key->conf;
 191                 return 0;
 192         }
 193
 194         /* Add room for ICV */
 195         skb_put(skb, TKIP_ICV_LEN);
 196
 197         hdr = (struct ieee80211_hdr *) skb->data;
 198         ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 199                                     key, pos, len, hdr->addr2);
 200         return 0;
 201 }
 202
 203
 204 ieee80211_tx_result
 205 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 206 {
 207         struct sk_buff *skb = tx->skb;
 208
 209         ieee80211_tx_set_protected(tx);
 210
 211         if (tkip_encrypt_skb(tx, skb) < 0)
 212                 return TX_DROP;
 213
 214         if (tx->extra_frag) {
 215                 int i;
 216                 for (i = 0; i < tx->num_extra_frag; i++) {
 217                         if (tkip_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 218                                 return TX_DROP;
 219                 }
 220         }
 221
 222         return TX_CONTINUE;
 223 }
 224
 225
 226 ieee80211_rx_result
 227 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 228 {
 229         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 230         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 231         struct ieee80211_key *key = rx->key;
 232         struct sk_buff *skb = rx->skb;
 233         DECLARE_MAC_BUF(mac);
 234
 235         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 236
 237         if (!ieee80211_is_data(hdr->frame_control))
 238                 return RX_CONTINUE;
 239
 240         if (!rx->sta || skb->len - hdrlen < 12)
 241                 return RX_DROP_UNUSABLE;
 242
 243         if (rx->status->flag & RX_FLAG_DECRYPTED) {
 244                 if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
 245                         /*
 246                          * Hardware took care of all processing, including
 247                          * replay protection, and stripped the ICV/IV so
 248                          * we cannot do any checks here.
 249                          */
 250                         return RX_CONTINUE;
 251                 }
 252
 253                 /* let TKIP code verify IV, but skip decryption */
 254                 hwaccel = 1;
 255         }
 256
 257         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 258                                           key, skb->data + hdrlen,
 259                                           skb->len - hdrlen, rx->sta->addr,
 260                                           hdr->addr1, hwaccel, rx->queue,
 261                                           &rx->tkip_iv32,
 262                                           &rx->tkip_iv16);
 263         if (res != TKIP_DECRYPT_OK || wpa_test)
 264                 return RX_DROP_UNUSABLE;
 265
 266         /* Trim ICV */
 267         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 268
 269         /* Remove IV */
 270         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 271         skb_pull(skb, TKIP_IV_LEN);
 272
 273         return RX_CONTINUE;
 274 }
 275
 276
 277 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
 278                                 int encrypted)
 279 {
 280         __le16 mask_fc;
 281         int a4_included;
 282         u8 qos_tid;
 283         u8 *b_0, *aad;
 284         u16 data_len, len_a;
 285         unsigned int hdrlen;
 286         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 287
 288         b_0 = scratch + 3 * AES_BLOCK_LEN;
 289         aad = scratch + 4 * AES_BLOCK_LEN;
 290
 291         /*
 292          * Mask FC: zero subtype b4 b5 b6
 293          * Retry, PwrMgt, MoreData; set Protected
 294          */
 295         mask_fc = hdr->frame_control;
 296         mask_fc &= ~cpu_to_le16(0x0070 | IEEE80211_FCTL_RETRY |
 297                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 298         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 299
 300         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 301         len_a = hdrlen - 2;
 302         a4_included = ieee80211_has_a4(hdr->frame_control);
 303
 304         if (ieee80211_is_data_qos(hdr->frame_control))
 305                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 306         else
 307                 qos_tid = 0;
 308
 309         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 310         if (encrypted)
 311                 data_len -= CCMP_MIC_LEN;
 312
 313         /* First block, b_0 */
 314         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 315         /* Nonce: QoS Priority | A2 | PN */
 316         b_0[1] = qos_tid;
 317         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
 318         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 319         /* l(m) */
 320         put_unaligned_be16(data_len, &b_0[14]);
 321
 322         /* AAD (extra authenticate-only data) / masked 802.11 header
 323          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 324         put_unaligned_be16(len_a, &aad[0]);
 325         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 326         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 327
 328         /* Mask Seq#, leave Frag# */
 329         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 330         aad[23] = 0;
 331
 332         if (a4_included) {
 333                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 334                 aad[30] = qos_tid;
 335                 aad[31] = 0;
 336         } else {
 337                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 338                 aad[24] = qos_tid;
 339         }
 340 }
 341
 342
 343 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 344 {
 345         hdr[0] = pn[5];
 346         hdr[1] = pn[4];
 347         hdr[2] = 0;
 348         hdr[3] = 0x20 | (key_id << 6);
 349         hdr[4] = pn[3];
 350         hdr[5] = pn[2];
 351         hdr[6] = pn[1];
 352         hdr[7] = pn[0];
 353 }
 354
 355
 356 static inline int ccmp_hdr2pn(u8 *pn, u8 *hdr)
 357 {
 358         pn[0] = hdr[7];
 359         pn[1] = hdr[6];
 360         pn[2] = hdr[5];
 361         pn[3] = hdr[4];
 362         pn[4] = hdr[1];
 363         pn[5] = hdr[0];
 364         return (hdr[3] >> 6) & 0x03;
 365 }
 366
 367
 368 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 369 {
 370         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 371         struct ieee80211_key *key = tx->key;
 372         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 373         int hdrlen, len, tail;
 374         u8 *pos, *pn;
 375         int i;
 376
 377         info->control.icv_len = CCMP_MIC_LEN;
 378         info->control.iv_len = CCMP_HDR_LEN;
 379
 380         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 381             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 382                 /* hwaccel - with no need for preallocated room for CCMP "
 383                  * header or MIC fields */
 384                 info->control.hw_key = &tx->key->conf;
 385                 return 0;
 386         }
 387
 388         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 389         len = skb->len - hdrlen;
 390
 391         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 392                 tail = 0;
 393         else
 394                 tail = CCMP_MIC_LEN;
 395
 396         if (WARN_ON(skb_tailroom(skb) < tail ||
 397                     skb_headroom(skb) < CCMP_HDR_LEN))
 398                 return -1;
 399
 400         pos = skb_push(skb, CCMP_HDR_LEN);
 401         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 402         hdr = (struct ieee80211_hdr *) pos;
 403         pos += hdrlen;
 404
 405         /* PN = PN + 1 */
 406         pn = key->u.ccmp.tx_pn;
 407
 408         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 409                 pn[i]++;
 410                 if (pn[i])
 411                         break;
 412         }
 413
 414         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 415
 416         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 417                 /* hwaccel - with preallocated room for CCMP header */
 418                 info->control.hw_key = &tx->key->conf;
 419                 return 0;
 420         }
 421
 422         pos += CCMP_HDR_LEN;
 423         ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
 424         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
 425                                   pos, skb_put(skb, CCMP_MIC_LEN));
 426
 427         return 0;
 428 }
 429
 430
 431 ieee80211_tx_result
 432 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 433 {
 434         struct sk_buff *skb = tx->skb;
 435
 436         ieee80211_tx_set_protected(tx);
 437
 438         if (ccmp_encrypt_skb(tx, skb) < 0)
 439                 return TX_DROP;
 440
 441         if (tx->extra_frag) {
 442                 int i;
 443                 for (i = 0; i < tx->num_extra_frag; i++) {
 444                         if (ccmp_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 445                                 return TX_DROP;
 446                 }
 447         }
 448
 449         return TX_CONTINUE;
 450 }
 451
 452
 453 ieee80211_rx_result
 454 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 455 {
 456         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
 457         int hdrlen;
 458         struct ieee80211_key *key = rx->key;
 459         struct sk_buff *skb = rx->skb;
 460         u8 pn[CCMP_PN_LEN];
 461         int data_len;
 462         DECLARE_MAC_BUF(mac);
 463
 464         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 465
 466         if (!ieee80211_is_data(hdr->frame_control))
 467                 return RX_CONTINUE;
 468
 469         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 470         if (!rx->sta || data_len < 0)
 471                 return RX_DROP_UNUSABLE;
 472
 473         if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
 474             (rx->status->flag & RX_FLAG_IV_STRIPPED))
 475                 return RX_CONTINUE;
 476
 477         (void) ccmp_hdr2pn(pn, skb->data + hdrlen);
 478
 479         if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
 480                 key->u.ccmp.replays++;
 481                 return RX_DROP_UNUSABLE;
 482         }
 483
 484         if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
 485                 /* hardware didn't decrypt/verify MIC */
 486                 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
 487
 488                 if (ieee80211_aes_ccm_decrypt(
 489                             key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
 490                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 491                             skb->data + skb->len - CCMP_MIC_LEN,
 492                             skb->data + hdrlen + CCMP_HDR_LEN)) {
 493                         return RX_DROP_UNUSABLE;
 494                 }
 495         }
 496
 497         memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
 498
 499         /* Remove CCMP header and MIC */
 500         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 501         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 502         skb_pull(skb, CCMP_HDR_LEN);
 503
 504         return RX_CONTINUE;
 505 }