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 <net/mac80211.h>
  15
  16 #include "ieee80211_i.h"
  17 #include "michael.h"
  18 #include "tkip.h"
  19 #include "aes_ccm.h"
  20 #include "wpa.h"
  21
  22 static int ieee80211_get_hdr_info(const struct sk_buff *skb, u8 **sa, u8 **da,
  23                                   u8 *qos_tid, u8 **data, size_t *data_len)
  24 {
  25         struct ieee80211_hdr *hdr;
  26         size_t hdrlen;
  27         __le16 fc;
  28
  29         hdr = (struct ieee80211_hdr *)skb->data;
  30         fc = hdr->frame_control;
  31
  32         hdrlen = ieee80211_hdrlen(fc);
  33
  34         *sa = ieee80211_get_SA(hdr);
  35         *da = ieee80211_get_DA(hdr);
  36
  37         *data = skb->data + hdrlen;
  38         *data_len = skb->len - hdrlen;
  39
  40         if (ieee80211_is_data_qos(fc))
  41                 *qos_tid = (*ieee80211_get_qos_ctl(hdr) & 0x0f) | 0x80;
  42         else
  43                 *qos_tid = 0;
  44
  45         return skb->len < hdrlen ? -1 : 0;
  46 }
  47
  48
  49 ieee80211_tx_result
  50 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
  51 {
  52         u8 *data, *sa, *da, *key, *mic, qos_tid;
  53         size_t data_len;
  54         u16 fc;
  55         struct sk_buff *skb = tx->skb;
  56         int authenticator;
  57         int wpa_test = 0;
  58         int tail;
  59
  60         fc = tx->fc;
  61
  62         if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
  63             !WLAN_FC_DATA_PRESENT(fc))
  64                 return TX_CONTINUE;
  65
  66         if (ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len))
  67                 return TX_DROP;
  68
  69         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
  70             !(tx->flags & IEEE80211_TX_FRAGMENTED) &&
  71             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) &&
  72             !wpa_test) {
  73                 /* hwaccel - with no need for preallocated room for Michael MIC
  74                  */
  75                 return TX_CONTINUE;
  76         }
  77
  78         tail = MICHAEL_MIC_LEN;
  79         if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  80                 tail += TKIP_ICV_LEN;
  81
  82         if (WARN_ON(skb_tailroom(skb) < tail ||
  83                     skb_headroom(skb) < TKIP_IV_LEN))
  84                 return TX_DROP;
  85
  86 #if 0
  87         authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
  88 #else
  89         authenticator = 1;
  90 #endif
  91         key = &tx->key->conf.key[authenticator ? ALG_TKIP_TEMP_AUTH_TX_MIC_KEY :
  92                                  ALG_TKIP_TEMP_AUTH_RX_MIC_KEY];
  93         mic = skb_put(skb, MICHAEL_MIC_LEN);
  94         michael_mic(key, da, sa, qos_tid & 0x0f, data, data_len, mic);
  95
  96         return TX_CONTINUE;
  97 }
  98
  99
 100 ieee80211_rx_result
 101 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
 102 {
 103         u8 *data, *sa, *da, *key = NULL, qos_tid;
 104         size_t data_len;
 105         u16 fc;
 106         u8 mic[MICHAEL_MIC_LEN];
 107         struct sk_buff *skb = rx->skb;
 108         int authenticator = 1, wpa_test = 0;
 109         DECLARE_MAC_BUF(mac);
 110
 111         fc = rx->fc;
 112
 113         /*
 114          * No way to verify the MIC if the hardware stripped it
 115          */
 116         if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
 117                 return RX_CONTINUE;
 118
 119         if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
 120             !(rx->fc & IEEE80211_FCTL_PROTECTED) || !WLAN_FC_DATA_PRESENT(fc))
 121                 return RX_CONTINUE;
 122
 123         if (ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len)
 124             || data_len < MICHAEL_MIC_LEN)
 125                 return RX_DROP_UNUSABLE;
 126
 127         data_len -= MICHAEL_MIC_LEN;
 128
 129 #if 0
 130         authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
 131 #else
 132         authenticator = 1;
 133 #endif
 134         key = &rx->key->conf.key[authenticator ? ALG_TKIP_TEMP_AUTH_RX_MIC_KEY :
 135                                  ALG_TKIP_TEMP_AUTH_TX_MIC_KEY];
 136         michael_mic(key, da, sa, qos_tid & 0x0f, data, data_len, mic);
 137         if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
 138                 if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 139                         return RX_DROP_UNUSABLE;
 140
 141                 printk(KERN_DEBUG "%s: invalid Michael MIC in data frame from "
 142                        "%s\n", rx->dev->name, print_mac(mac, sa));
 143
 144                 mac80211_ev_michael_mic_failure(rx->dev, rx->key->conf.keyidx,
 145                                                 (void *) skb->data);
 146                 return RX_DROP_UNUSABLE;
 147         }
 148
 149         /* remove Michael MIC from payload */
 150         skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
 151
 152         /* update IV in key information to be able to detect replays */
 153         rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
 154         rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
 155
 156         return RX_CONTINUE;
 157 }
 158
 159
 160 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 161 {
 162         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 163         struct ieee80211_key *key = tx->key;
 164         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 165         unsigned int hdrlen;
 166         int len, tail;
 167         u8 *pos;
 168
 169         info->control.icv_len = TKIP_ICV_LEN;
 170         info->control.iv_len = TKIP_IV_LEN;
 171
 172         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 173             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 174                 /* hwaccel - with no need for preallocated room for IV/ICV */
 175                 info->control.hw_key = &tx->key->conf;
 176                 return 0;
 177         }
 178
 179         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 180         len = skb->len - hdrlen;
 181
 182         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 183                 tail = 0;
 184         else
 185                 tail = TKIP_ICV_LEN;
 186
 187         if (WARN_ON(skb_tailroom(skb) < tail ||
 188                     skb_headroom(skb) < TKIP_IV_LEN))
 189                 return -1;
 190
 191         pos = skb_push(skb, TKIP_IV_LEN);
 192         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
 193         pos += hdrlen;
 194
 195         /* Increase IV for the frame */
 196         key->u.tkip.tx.iv16++;
 197         if (key->u.tkip.tx.iv16 == 0)
 198                 key->u.tkip.tx.iv32++;
 199
 200         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 201                 /* hwaccel - with preallocated room for IV */
 202                 ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 203
 204                 info->control.hw_key = &tx->key->conf;
 205                 return 0;
 206         }
 207
 208         /* Add room for ICV */
 209         skb_put(skb, TKIP_ICV_LEN);
 210
 211         hdr = (struct ieee80211_hdr *) skb->data;
 212         ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
 213                                     key, pos, len, hdr->addr2);
 214         return 0;
 215 }
 216
 217
 218 ieee80211_tx_result
 219 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
 220 {
 221         struct sk_buff *skb = tx->skb;
 222
 223         ieee80211_tx_set_protected(tx);
 224
 225         if (tkip_encrypt_skb(tx, skb) < 0)
 226                 return TX_DROP;
 227
 228         if (tx->extra_frag) {
 229                 int i;
 230                 for (i = 0; i < tx->num_extra_frag; i++) {
 231                         if (tkip_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 232                                 return TX_DROP;
 233                 }
 234         }
 235
 236         return TX_CONTINUE;
 237 }
 238
 239
 240 ieee80211_rx_result
 241 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 242 {
 243         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 244         int hdrlen, res, hwaccel = 0, wpa_test = 0;
 245         struct ieee80211_key *key = rx->key;
 246         struct sk_buff *skb = rx->skb;
 247         DECLARE_MAC_BUF(mac);
 248
 249         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 250
 251         if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
 252                 return RX_CONTINUE;
 253
 254         if (!rx->sta || skb->len - hdrlen < 12)
 255                 return RX_DROP_UNUSABLE;
 256
 257         if (rx->status->flag & RX_FLAG_DECRYPTED) {
 258                 if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
 259                         /*
 260                          * Hardware took care of all processing, including
 261                          * replay protection, and stripped the ICV/IV so
 262                          * we cannot do any checks here.
 263                          */
 264                         return RX_CONTINUE;
 265                 }
 266
 267                 /* let TKIP code verify IV, but skip decryption */
 268                 hwaccel = 1;
 269         }
 270
 271         res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
 272                                           key, skb->data + hdrlen,
 273                                           skb->len - hdrlen, rx->sta->addr,
 274                                           hdr->addr1, hwaccel, rx->queue,
 275                                           &rx->tkip_iv32,
 276                                           &rx->tkip_iv16);
 277         if (res != TKIP_DECRYPT_OK || wpa_test) {
 278 #ifdef CONFIG_MAC80211_DEBUG
 279                 if (net_ratelimit())
 280                         printk(KERN_DEBUG "%s: TKIP decrypt failed for RX "
 281                                "frame from %s (res=%d)\n", rx->dev->name,
 282                                print_mac(mac, rx->sta->addr), res);
 283 #endif /* CONFIG_MAC80211_DEBUG */
 284                 return RX_DROP_UNUSABLE;
 285         }
 286
 287         /* Trim ICV */
 288         skb_trim(skb, skb->len - TKIP_ICV_LEN);
 289
 290         /* Remove IV */
 291         memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
 292         skb_pull(skb, TKIP_IV_LEN);
 293
 294         return RX_CONTINUE;
 295 }
 296
 297
 298 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
 299                                 int encrypted)
 300 {
 301         u16 fc;
 302         int a4_included, qos_included;
 303         u8 qos_tid, *fc_pos, *data, *sa, *da;
 304         int len_a;
 305         size_t data_len;
 306         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 307
 308         fc_pos = (u8 *) &hdr->frame_control;
 309         fc = fc_pos[0] ^ (fc_pos[1] << 8);
 310         a4_included = (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
 311                 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS);
 312
 313         ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len);
 314         data_len -= CCMP_HDR_LEN + (encrypted ? CCMP_MIC_LEN : 0);
 315         if (qos_tid & 0x80) {
 316                 qos_included = 1;
 317                 qos_tid &= 0x0f;
 318         } else
 319                 qos_included = 0;
 320         /* First block, b_0 */
 321
 322         b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
 323         /* Nonce: QoS Priority | A2 | PN */
 324         b_0[1] = qos_tid;
 325         memcpy(&b_0[2], hdr->addr2, 6);
 326         memcpy(&b_0[8], pn, CCMP_PN_LEN);
 327         /* l(m) */
 328         b_0[14] = (data_len >> 8) & 0xff;
 329         b_0[15] = data_len & 0xff;
 330
 331
 332         /* AAD (extra authenticate-only data) / masked 802.11 header
 333          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
 334
 335         len_a = a4_included ? 28 : 22;
 336         if (qos_included)
 337                 len_a += 2;
 338
 339         aad[0] = 0; /* (len_a >> 8) & 0xff; */
 340         aad[1] = len_a & 0xff;
 341         /* Mask FC: zero subtype b4 b5 b6 */
 342         aad[2] = fc_pos[0] & ~(BIT(4) | BIT(5) | BIT(6));
 343         /* Retry, PwrMgt, MoreData; set Protected */
 344         aad[3] = (fc_pos[1] & ~(BIT(3) | BIT(4) | BIT(5))) | BIT(6);
 345         memcpy(&aad[4], &hdr->addr1, 18);
 346
 347         /* Mask Seq#, leave Frag# */
 348         aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
 349         aad[23] = 0;
 350         if (a4_included) {
 351                 memcpy(&aad[24], hdr->addr4, 6);
 352                 aad[30] = 0;
 353                 aad[31] = 0;
 354         } else
 355                 memset(&aad[24], 0, 8);
 356         if (qos_included) {
 357                 u8 *dpos = &aad[a4_included ? 30 : 24];
 358
 359                 /* Mask QoS Control field */
 360                 dpos[0] = qos_tid;
 361                 dpos[1] = 0;
 362         }
 363 }
 364
 365
 366 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
 367 {
 368         hdr[0] = pn[5];
 369         hdr[1] = pn[4];
 370         hdr[2] = 0;
 371         hdr[3] = 0x20 | (key_id << 6);
 372         hdr[4] = pn[3];
 373         hdr[5] = pn[2];
 374         hdr[6] = pn[1];
 375         hdr[7] = pn[0];
 376 }
 377
 378
 379 static inline int ccmp_hdr2pn(u8 *pn, u8 *hdr)
 380 {
 381         pn[0] = hdr[7];
 382         pn[1] = hdr[6];
 383         pn[2] = hdr[5];
 384         pn[3] = hdr[4];
 385         pn[4] = hdr[1];
 386         pn[5] = hdr[0];
 387         return (hdr[3] >> 6) & 0x03;
 388 }
 389
 390
 391 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 392 {
 393         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 394         struct ieee80211_key *key = tx->key;
 395         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 396         int hdrlen, len, tail;
 397         u8 *pos, *pn, *b_0, *aad, *scratch;
 398         int i;
 399
 400         info->control.icv_len = CCMP_MIC_LEN;
 401         info->control.iv_len = CCMP_HDR_LEN;
 402
 403         if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 404             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
 405                 /* hwaccel - with no need for preallocated room for CCMP "
 406                  * header or MIC fields */
 407                 info->control.hw_key = &tx->key->conf;
 408                 return 0;
 409         }
 410
 411         scratch = key->u.ccmp.tx_crypto_buf;
 412         b_0 = scratch + 3 * AES_BLOCK_LEN;
 413         aad = scratch + 4 * AES_BLOCK_LEN;
 414
 415         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 416         len = skb->len - hdrlen;
 417
 418         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 419                 tail = 0;
 420         else
 421                 tail = CCMP_MIC_LEN;
 422
 423         if (WARN_ON(skb_tailroom(skb) < tail ||
 424                     skb_headroom(skb) < CCMP_HDR_LEN))
 425                 return -1;
 426
 427         pos = skb_push(skb, CCMP_HDR_LEN);
 428         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
 429         hdr = (struct ieee80211_hdr *) pos;
 430         pos += hdrlen;
 431
 432         /* PN = PN + 1 */
 433         pn = key->u.ccmp.tx_pn;
 434
 435         for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
 436                 pn[i]++;
 437                 if (pn[i])
 438                         break;
 439         }
 440
 441         ccmp_pn2hdr(pos, pn, key->conf.keyidx);
 442
 443         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 444                 /* hwaccel - with preallocated room for CCMP header */
 445                 info->control.hw_key = &tx->key->conf;
 446                 return 0;
 447         }
 448
 449         pos += CCMP_HDR_LEN;
 450         ccmp_special_blocks(skb, pn, b_0, aad, 0);
 451         ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, b_0, aad, pos, len,
 452                                   pos, skb_put(skb, CCMP_MIC_LEN));
 453
 454         return 0;
 455 }
 456
 457
 458 ieee80211_tx_result
 459 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
 460 {
 461         struct sk_buff *skb = tx->skb;
 462
 463         ieee80211_tx_set_protected(tx);
 464
 465         if (ccmp_encrypt_skb(tx, skb) < 0)
 466                 return TX_DROP;
 467
 468         if (tx->extra_frag) {
 469                 int i;
 470                 for (i = 0; i < tx->num_extra_frag; i++) {
 471                         if (ccmp_encrypt_skb(tx, tx->extra_frag[i]) < 0)
 472                                 return TX_DROP;
 473                 }
 474         }
 475
 476         return TX_CONTINUE;
 477 }
 478
 479
 480 ieee80211_rx_result
 481 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 482 {
 483         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
 484         int hdrlen;
 485         struct ieee80211_key *key = rx->key;
 486         struct sk_buff *skb = rx->skb;
 487         u8 pn[CCMP_PN_LEN];
 488         int data_len;
 489         DECLARE_MAC_BUF(mac);
 490
 491         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 492
 493         if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
 494                 return RX_CONTINUE;
 495
 496         data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
 497         if (!rx->sta || data_len < 0)
 498                 return RX_DROP_UNUSABLE;
 499
 500         if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
 501             (rx->status->flag & RX_FLAG_IV_STRIPPED))
 502                 return RX_CONTINUE;
 503
 504         (void) ccmp_hdr2pn(pn, skb->data + hdrlen);
 505
 506         if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
 507 #ifdef CONFIG_MAC80211_DEBUG
 508                 u8 *ppn = key->u.ccmp.rx_pn[rx->queue];
 509
 510                 printk(KERN_DEBUG "%s: CCMP replay detected for RX frame from "
 511                        "%s (RX PN %02x%02x%02x%02x%02x%02x <= prev. PN "
 512                        "%02x%02x%02x%02x%02x%02x)\n", rx->dev->name,
 513                        print_mac(mac, rx->sta->addr),
 514                        pn[0], pn[1], pn[2], pn[3], pn[4], pn[5],
 515                        ppn[0], ppn[1], ppn[2], ppn[3], ppn[4], ppn[5]);
 516 #endif /* CONFIG_MAC80211_DEBUG */
 517                 key->u.ccmp.replays++;
 518                 return RX_DROP_UNUSABLE;
 519         }
 520
 521         if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
 522                 /* hardware didn't decrypt/verify MIC */
 523                 u8 *scratch, *b_0, *aad;
 524
 525                 scratch = key->u.ccmp.rx_crypto_buf;
 526                 b_0 = scratch + 3 * AES_BLOCK_LEN;
 527                 aad = scratch + 4 * AES_BLOCK_LEN;
 528
 529                 ccmp_special_blocks(skb, pn, b_0, aad, 1);
 530
 531                 if (ieee80211_aes_ccm_decrypt(
 532                             key->u.ccmp.tfm, scratch, b_0, aad,
 533                             skb->data + hdrlen + CCMP_HDR_LEN, data_len,
 534                             skb->data + skb->len - CCMP_MIC_LEN,
 535                             skb->data + hdrlen + CCMP_HDR_LEN)) {
 536 #ifdef CONFIG_MAC80211_DEBUG
 537                         if (net_ratelimit())
 538                                 printk(KERN_DEBUG "%s: CCMP decrypt failed "
 539                                        "for RX frame from %s\n", rx->dev->name,
 540                                        print_mac(mac, rx->sta->addr));
 541 #endif /* CONFIG_MAC80211_DEBUG */
 542                         return RX_DROP_UNUSABLE;
 543                 }
 544         }
 545
 546         memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
 547
 548         /* Remove CCMP header and MIC */
 549         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 550         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
 551         skb_pull(skb, CCMP_HDR_LEN);
 552
 553         return RX_CONTINUE;
 554 }