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         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 156             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 157                 /* hwaccel - with no need for preallocated room for IV/ICV */
 158                 info->control.hw_key = &tx->key->conf;
 159                 return 0;
 160         }
 161
 162         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 163         len = skb->len - hdrlen;
 164
 165         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 166                 tail = 0;
 167         else
 168                 tail = TKIP_ICV_LEN;
 169
 170         if (WARN_ON(skb_tailroom(skb) < tail ||
 171                     skb_headroom(skb) < TKIP_IV_LEN))
 172                 return -1;
 173
 174         pos = skb_push(skb, TKIP_IV_LEN);
 175         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 176         pos += hdrlen;
 177
 178         /* Increase IV for the frame */
 179         key->u.tkip.tx.iv16++;
 180         if (key->u.tkip.tx.iv16 == 0)
 181                 key->u.tkip.tx.iv32++;
 182
 183         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 184                 /* hwaccel - with preallocated room for IV */
 185                 ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 186
 187                 info->control.hw_key = &tx->key->conf;
 188                 return 0;
 189         }
 190
 191         /* Add room for ICV */
 192         skb_put(skb, TKIP_ICV_LEN);
 193
 194         hdr = (struct ieee80211_hdr *) skb->data;
 195         ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 196                                     key, pos, len, hdr->addr2);
 197         return 0;
 198 }
 199
 200
 201 ieee80211_tx_result
 202 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 203 {
 204         struct sk_buff *skb = tx->skb;
 205
 206         ieee80211_tx_set_protected(tx);
 207
 208         if (tkip_encrypt_skb(tx, skb) < 0)
 209                 return TX_DROP;
 210
 211         if (tx->extra_frag) {
 212                 int i;
 213                 for (i = 0; i < tx->num_extra_frag; i++) {
 214                         if (tkip_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 215                                 return TX_DROP;
 216                 }
 217         }
 218
 219         return TX_CONTINUE;
 220 }
 221
 222
 223 ieee80211_rx_result
 224 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 225 {
 226         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 227         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 228         struct ieee80211_key *key = rx->key;
 229         struct sk_buff *skb = rx->skb;
 230         DECLARE_MAC_BUF(mac);
 231
 232         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 233
 234         if (!ieee80211_is_data(hdr->frame_control))
 235                 return RX_CONTINUE;
 236
 237         if (!rx->sta || skb->len - hdrlen < 12)
 238                 return RX_DROP_UNUSABLE;
 239
 240         if (rx->status->flag & RX_FLAG_DECRYPTED) {
 241                 if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
 242                         /*
 243                          * Hardware took care of all processing, including
 244                          * replay protection, and stripped the ICV/IV so
 245                          * we cannot do any checks here.
 246                          */
 247                         return RX_CONTINUE;
 248                 }
 249
 250                 /* let TKIP code verify IV, but skip decryption */
 251                 hwaccel = 1;
 252         }
 253
 254         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 255                                           key, skb->data + hdrlen,
 256                                           skb->len - hdrlen, rx->sta->sta.addr,
 257                                           hdr->addr1, hwaccel, rx->queue,
 258                                           &rx->tkip_iv32,
 259                                           &rx->tkip_iv16);
 260         if (res != TKIP_DECRYPT_OK || wpa_test)
 261                 return RX_DROP_UNUSABLE;
 262
 263         /* Trim ICV */
 264         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 265
 266         /* Remove IV */
 267         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 268         skb_pull(skb, TKIP_IV_LEN);
 269
 270         return RX_CONTINUE;
 271 }
 272
 273
 274 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
 275                                 int encrypted)
 276 {
 277         __le16 mask_fc;
 278         int a4_included;
 279         u8 qos_tid;
 280         u8 *b_0, *aad;
 281         u16 data_len, len_a;
 282         unsigned int hdrlen;
 283         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 284
 285         b_0 = scratch + 3 * AES_BLOCK_LEN;
 286         aad = scratch + 4 * AES_BLOCK_LEN;
 287
 288         /*
 289          * Mask FC: zero subtype b4 b5 b6
 290          * Retry, PwrMgt, MoreData; set Protected
 291          */
 292         mask_fc = hdr->frame_control;
 293         mask_fc &= ~cpu_to_le16(0x0070 | IEEE80211_FCTL_RETRY |
 294                                 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
 295         mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 296
 297         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 298         len_a = hdrlen - 2;
 299         a4_included = ieee80211_has_a4(hdr->frame_control);
 300
 301         if (ieee80211_is_data_qos(hdr->frame_control))
 302                 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 303         else
 304                 qos_tid = 0;
 305
 306         data_len = skb->len - hdrlen - CCMP_HDR_LEN;
 307         if (encrypted)
 308                 data_len -= CCMP_MIC_LEN;
 309
 310         /* First block, b_0 */
 311         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 312         /* Nonce: QoS Priority | A2 | PN */
 313         b_0[1] = qos_tid;
 314         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
 315         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 316         /* l(m) */
 317         put_unaligned_be16(data_len, &b_0[14]);
 318
 319         /* AAD (extra authenticate-only data) / masked 802.11 header
 320          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 321         put_unaligned_be16(len_a, &aad[0]);
 322         put_unaligned(mask_fc, (__le16 *)&aad[2]);
 323         memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
 324
 325         /* Mask Seq#, leave Frag# */
 326         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 327         aad[23] = 0;
 328
 329         if (a4_included) {
 330                 memcpy(&aad[24], hdr->addr4, ETH_ALEN);
 331                 aad[30] = qos_tid;
 332                 aad[31] = 0;
 333         } else {
 334                 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
 335                 aad[24] = qos_tid;
 336         }
 337 }
 338
 339
 340 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 341 {
 342         hdr[0] = pn[5];
 343         hdr[1] = pn[4];
 344         hdr[2] = 0;
 345         hdr[3] = 0x20 | (key_id << 6);
 346         hdr[4] = pn[3];
 347         hdr[5] = pn[2];
 348         hdr[6] = pn[1];
 349         hdr[7] = pn[0];
 350 }
 351
 352
 353 static inline int ccmp_hdr2pn(u8 *pn, u8 *hdr)
 354 {
 355         pn[0] = hdr[7];
 356         pn[1] = hdr[6];
 357         pn[2] = hdr[5];
 358         pn[3] = hdr[4];
 359         pn[4] = hdr[1];
 360         pn[5] = hdr[0];
 361         return (hdr[3] >> 6) & 0x03;
 362 }
 363
 364
 365 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 366 {
 367         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 368         struct ieee80211_key *key = tx->key;
 369         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 370         int hdrlen, len, tail;
 371         u8 *pos, *pn;
 372         int i;
 373
 374         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 375             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 376                 /* hwaccel - with no need for preallocated room for CCMP "
 377                  * header or MIC fields */
 378                 info->control.hw_key = &tx->key->conf;
 379                 return 0;
 380         }
 381
 382         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 383         len = skb->len - hdrlen;
 384
 385         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 386                 tail = 0;
 387         else
 388                 tail = CCMP_MIC_LEN;
 389
 390         if (WARN_ON(skb_tailroom(skb) < tail ||
 391                     skb_headroom(skb) < CCMP_HDR_LEN))
 392                 return -1;
 393
 394         pos = skb_push(skb, CCMP_HDR_LEN);
 395         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 396         hdr = (struct ieee80211_hdr *) pos;
 397         pos += hdrlen;
 398
 399         /* PN = PN + 1 */
 400         pn = key->u.ccmp.tx_pn;
 401
 402         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 403                 pn[i]++;
 404                 if (pn[i])
 405                         break;
 406         }
 407
 408         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 409
 410         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 411                 /* hwaccel - with preallocated room for CCMP header */
 412                 info->control.hw_key = &tx->key->conf;
 413                 return 0;
 414         }
 415
 416         pos += CCMP_HDR_LEN;
 417         ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
 418         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
 419                                   pos, skb_put(skb, CCMP_MIC_LEN));
 420
 421         return 0;
 422 }
 423
 424
 425 ieee80211_tx_result
 426 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 427 {
 428         struct sk_buff *skb = tx->skb;
 429
 430         ieee80211_tx_set_protected(tx);
 431
 432         if (ccmp_encrypt_skb(tx, skb) < 0)
 433                 return TX_DROP;
 434
 435         if (tx->extra_frag) {
 436                 int i;
 437                 for (i = 0; i < tx->num_extra_frag; i++) {
 438                         if (ccmp_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 439                                 return TX_DROP;
 440                 }
 441         }
 442
 443         return TX_CONTINUE;
 444 }
 445
 446
 447 ieee80211_rx_result
 448 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 449 {
 450         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
 451         int hdrlen;
 452         struct ieee80211_key *key = rx->key;
 453         struct sk_buff *skb = rx->skb;
 454         u8 pn[CCMP_PN_LEN];
 455         int data_len;
 456         DECLARE_MAC_BUF(mac);
 457
 458         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 459
 460         if (!ieee80211_is_data(hdr->frame_control))
 461                 return RX_CONTINUE;
 462
 463         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 464         if (!rx->sta || data_len < 0)
 465                 return RX_DROP_UNUSABLE;
 466
 467         if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
 468             (rx->status->flag & RX_FLAG_IV_STRIPPED))
 469                 return RX_CONTINUE;
 470
 471         (void) ccmp_hdr2pn(pn, skb->data + hdrlen);
 472
 473         if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
 474                 key->u.ccmp.replays++;
 475                 return RX_DROP_UNUSABLE;
 476         }
 477
 478         if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
 479                 /* hardware didn't decrypt/verify MIC */
 480                 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
 481
 482                 if (ieee80211_aes_ccm_decrypt(
 483                             key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
 484                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 485                             skb->data + skb->len - CCMP_MIC_LEN,
 486                             skb->data + hdrlen + CCMP_HDR_LEN)) {
 487                         return RX_DROP_UNUSABLE;
 488                 }
 489         }
 490
 491         memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
 492
 493         /* Remove CCMP header and MIC */
 494         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 495         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 496         skb_pull(skb, CCMP_HDR_LEN);
 497
 498         return RX_CONTINUE;
 499 }