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