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 MMIC */
  53                 return TX_CONTINUE;
  54         }
  55
  56         tail = MICHAEL_MIC_LEN;
  57         if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  58                 tail += TKIP_ICV_LEN;
  59
  60         if (WARN_ON(skb_tailroom(skb) < tail ||
  61                     skb_headroom(skb) < TKIP_IV_LEN))
  62                 return TX_DROP;
  63
  64 #if 0
  65         authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
  66 #else
  67         authenticator = 1;
  68 #endif
  69         key_offset = authenticator ?
  70                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
  71                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
  72         key = &tx->key->conf.key[key_offset];
  73         mic = skb_put(skb, MICHAEL_MIC_LEN);
  74         michael_mic(key, hdr, data, data_len, mic);
  75
  76         return TX_CONTINUE;
  77 }
  78
  79
  80 ieee80211_rx_result
  81 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
  82 {
  83         u8 *data, *key = NULL, key_offset;
  84         size_t data_len;
  85         unsigned int hdrlen;
  86         struct ieee80211_hdr *hdr;
  87         u8 mic[MICHAEL_MIC_LEN];
  88         struct sk_buff *skb = rx->skb;
  89         int authenticator = 1, wpa_test = 0;
  90
  91         /* No way to verify the MIC if the hardware stripped it */
  92         if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
  93                 return RX_CONTINUE;
  94
  95         hdr = (struct ieee80211_hdr *)skb->data;
  96         if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
  97             !ieee80211_has_protected(hdr->frame_control) ||
  98             !ieee80211_is_data_present(hdr->frame_control))
  99                 return RX_CONTINUE;
 100
 101         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 102         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
 103                 return RX_DROP_UNUSABLE;
 104
 105         data = skb->data + hdrlen;
 106         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
 107
 108 #if 0
 109         authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
 110 #else
 111         authenticator = 1;
 112 #endif
 113         key_offset = authenticator ?
 114                 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
 115                 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
 116         key = &rx->key->conf.key[key_offset];
 117         michael_mic(key, hdr, data, data_len, mic);
 118         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
 119                 if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 120                         return RX_DROP_UNUSABLE;
 121
 122                 mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
 123                                                 (void *) skb->data);
 124                 return RX_DROP_UNUSABLE;
 125         }
 126
 127         /* remove Michael MIC from payload */
 128         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
 129
 130         /* update IV in key information to be able to detect replays */
 131         rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
 132         rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
 133
 134         return RX_CONTINUE;
 135 }
 136
 137
 138 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 139 {
 140         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 141         struct ieee80211_key *key = tx->key;
 142         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 143         unsigned int hdrlen;
 144         int len, tail;
 145         u8 *pos;
 146
 147         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 148             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 149                 /* hwaccel - with no need for preallocated room for IV/ICV */
 150                 info->control.hw_key = &tx->key->conf;
 151                 return 0;
 152         }
 153
 154         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 155         len = skb->len - hdrlen;
 156
 157         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 158                 tail = 0;
 159         else
 160                 tail = TKIP_ICV_LEN;
 161
 162         if (WARN_ON(skb_tailroom(skb) < tail ||
 163                     skb_headroom(skb) < TKIP_IV_LEN))
 164                 return -1;
 165
 166         pos = skb_push(skb, TKIP_IV_LEN);
 167         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 168         pos += hdrlen;
 169
 170         /* Increase IV for the frame */
 171         key->u.tkip.tx.iv16++;
 172         if (key->u.tkip.tx.iv16 == 0)
 173                 key->u.tkip.tx.iv32++;
 174
 175         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 176                 /* hwaccel - with preallocated room for IV */
 177                 ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 178
 179                 info->control.hw_key = &tx->key->conf;
 180                 return 0;
 181         }
 182
 183         /* Add room for ICV */
 184         skb_put(skb, TKIP_ICV_LEN);
 185
 186         hdr = (struct ieee80211_hdr *) skb->data;
 187         ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 188                                     key, pos, len, hdr->addr2);
 189         return 0;
 190 }
 191
 192
 193 ieee80211_tx_result
 194 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 195 {
 196         struct sk_buff *skb = tx->skb;
 197         int i;
 198
 199         ieee80211_tx_set_protected(tx);
 200
 201         if (tkip_encrypt_skb(tx, skb) < 0)
 202                 return TX_DROP;
 203
 204         if (tx->extra_frag) {
 205                 for (i = 0; i < tx->num_extra_frag; i++) {
 206                         if (tkip_encrypt_skb(tx, tx->extra_frag[i]))
 207                                 return TX_DROP;
 208                 }
 209         }
 210
 211         return TX_CONTINUE;
 212 }
 213
 214
 215 ieee80211_rx_result
 216 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 217 {
 218         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 219         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 220         struct ieee80211_key *key = rx->key;
 221         struct sk_buff *skb = rx->skb;
 222
 223         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 224
 225         if (!ieee80211_is_data(hdr->frame_control))
 226                 return RX_CONTINUE;
 227
 228         if (!rx->sta || skb->len - hdrlen < 12)
 229                 return RX_DROP_UNUSABLE;
 230
 231         if (rx->status->flag & RX_FLAG_DECRYPTED) {
 232                 if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
 233                         /*
 234                          * Hardware took care of all processing, including
 235                          * replay protection, and stripped the ICV/IV so
 236                          * we cannot do any checks here.
 237                          */
 238                         return RX_CONTINUE;
 239                 }
 240
 241                 /* let TKIP code verify IV, but skip decryption */
 242                 hwaccel = 1;
 243         }
 244
 245         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 246                                           key, skb->data + hdrlen,
 247                                           skb->len - hdrlen, rx->sta->sta.addr,
 248                                           hdr->addr1, hwaccel, rx->queue,
 249                                           &rx->tkip_iv32,
 250                                           &rx->tkip_iv16);
 251         if (res != TKIP_DECRYPT_OK || wpa_test)
 252                 return RX_DROP_UNUSABLE;
 253
 254         /* Trim ICV */
 255         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 256
 257         /* Remove IV */
 258         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 259         skb_pull(skb, TKIP_IV_LEN);
 260
 261         return RX_CONTINUE;
 262 }
 263
 264
 265 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
 266                                 int encrypted)
 267 {
 268         __le16 mask_fc;
 269         int a4_included;
 270         u8 qos_tid;
 271         u8 *b_0, *aad;
 272         u16 data_len, len_a;
 273         unsigned int hdrlen;
 274         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 275
 276         b_0 = scratch + 3 * AES_BLOCK_LEN;
 277         aad = scratch + 4 * AES_BLOCK_LEN;
 278
 279         /*
 280          * Mask FC: zero subtype b4 b5 b6
 281          * Retry, PwrMgt, MoreData; set Protected
 282          */
 283         mask_fc = hdr->frame_control;
 284         mask_fc &= ~cpu_to_le16(0x0070 | IEEE80211_FCTL_RETRY |
 285                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 286         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 287
 288         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 289         len_a = hdrlen - 2;
 290         a4_included = ieee80211_has_a4(hdr->frame_control);
 291
 292         if (ieee80211_is_data_qos(hdr->frame_control))
 293                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 294         else
 295                 qos_tid = 0;
 296
 297         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 298         if (encrypted)
 299                 data_len -= CCMP_MIC_LEN;
 300
 301         /* First block, b_0 */
 302         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 303         /* Nonce: QoS Priority | A2 | PN */
 304         b_0[1] = qos_tid;
 305         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
 306         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 307         /* l(m) */
 308         put_unaligned_be16(data_len, &b_0[14]);
 309
 310         /* AAD (extra authenticate-only data) / masked 802.11 header
 311          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 312         put_unaligned_be16(len_a, &aad[0]);
 313         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 314         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 315
 316         /* Mask Seq#, leave Frag# */
 317         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 318         aad[23] = 0;
 319
 320         if (a4_included) {
 321                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 322                 aad[30] = qos_tid;
 323                 aad[31] = 0;
 324         } else {
 325                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 326                 aad[24] = qos_tid;
 327         }
 328 }
 329
 330
 331 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 332 {
 333         hdr[0] = pn[5];
 334         hdr[1] = pn[4];
 335         hdr[2] = 0;
 336         hdr[3] = 0x20 | (key_id << 6);
 337         hdr[4] = pn[3];
 338         hdr[5] = pn[2];
 339         hdr[6] = pn[1];
 340         hdr[7] = pn[0];
 341 }
 342
 343
 344 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
 345 {
 346         pn[0] = hdr[7];
 347         pn[1] = hdr[6];
 348         pn[2] = hdr[5];
 349         pn[3] = hdr[4];
 350         pn[4] = hdr[1];
 351         pn[5] = hdr[0];
 352 }
 353
 354
 355 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 356 {
 357         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 358         struct ieee80211_key *key = tx->key;
 359         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 360         int hdrlen, len, tail;
 361         u8 *pos, *pn;
 362         int i;
 363
 364         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 365             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 366                 /* hwaccel - with no need for preallocated room for CCMP
 367                  * header or MIC fields */
 368                 info->control.hw_key = &tx->key->conf;
 369                 return 0;
 370         }
 371
 372         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 373         len = skb->len - hdrlen;
 374
 375         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 376                 tail = 0;
 377         else
 378                 tail = CCMP_MIC_LEN;
 379
 380         if (WARN_ON(skb_tailroom(skb) < tail ||
 381                     skb_headroom(skb) < CCMP_HDR_LEN))
 382                 return -1;
 383
 384         pos = skb_push(skb, CCMP_HDR_LEN);
 385         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 386         hdr = (struct ieee80211_hdr *) pos;
 387         pos += hdrlen;
 388
 389         /* PN = PN + 1 */
 390         pn = key->u.ccmp.tx_pn;
 391
 392         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 393                 pn[i]++;
 394                 if (pn[i])
 395                         break;
 396         }
 397
 398         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 399
 400         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 401                 /* hwaccel - with preallocated room for CCMP header */
 402                 info->control.hw_key = &tx->key->conf;
 403                 return 0;
 404         }
 405
 406         pos += CCMP_HDR_LEN;
 407         ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
 408         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
 409                                   pos, skb_put(skb, CCMP_MIC_LEN));
 410
 411         return 0;
 412 }
 413
 414
 415 ieee80211_tx_result
 416 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 417 {
 418         struct sk_buff *skb = tx->skb;
 419         int i;
 420
 421         ieee80211_tx_set_protected(tx);
 422
 423         if (ccmp_encrypt_skb(tx, skb) < 0)
 424                 return TX_DROP;
 425
 426         if (tx->extra_frag) {
 427                 for (i = 0; i < tx->num_extra_frag; i++) {
 428                         if (ccmp_encrypt_skb(tx, tx->extra_frag[i]))
 429                                 return TX_DROP;
 430                 }
 431         }
 432
 433         return TX_CONTINUE;
 434 }
 435
 436
 437 ieee80211_rx_result
 438 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 439 {
 440         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
 441         int hdrlen;
 442         struct ieee80211_key *key = rx->key;
 443         struct sk_buff *skb = rx->skb;
 444         u8 pn[CCMP_PN_LEN];
 445         int data_len;
 446
 447         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 448
 449         if (!ieee80211_is_data(hdr->frame_control))
 450                 return RX_CONTINUE;
 451
 452         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 453         if (!rx->sta || data_len < 0)
 454                 return RX_DROP_UNUSABLE;
 455
 456         if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
 457             (rx->status->flag & RX_FLAG_IV_STRIPPED))
 458                 return RX_CONTINUE;
 459
 460         ccmp_hdr2pn(pn, skb->data + hdrlen);
 461
 462         if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
 463                 key->u.ccmp.replays++;
 464                 return RX_DROP_UNUSABLE;
 465         }
 466
 467         if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
 468                 /* hardware didn't decrypt/verify MIC */
 469                 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
 470
 471                 if (ieee80211_aes_ccm_decrypt(
 472                             key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
 473                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 474                             skb->data + skb->len - CCMP_MIC_LEN,
 475                             skb->data + hdrlen + CCMP_HDR_LEN))
 476                         return RX_DROP_UNUSABLE;
 477         }
 478
 479         memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
 480
 481         /* Remove CCMP header and MIC */
 482         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 483         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 484         skb_pull(skb, CCMP_HDR_LEN);
 485
 486         return RX_CONTINUE;
 487 }