drivers/staging/rtl8192e/rtllib_crypt_ccmp.c

   1 /*
   2  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
   3  *
   4  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation. See README and COPYING for
   9  * more details.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/random.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/if_arp.h>
  20 #include <linux/string.h>
  21 #include <linux/wireless.h>
  22 #include "rtllib.h"
  23
  24 #include <linux/crypto.h>
  25
  26 #include <linux/scatterlist.h>
  27
  28 #define AES_BLOCK_LEN 16
  29 #define CCMP_HDR_LEN 8
  30 #define CCMP_MIC_LEN 8
  31 #define CCMP_TK_LEN 16
  32 #define CCMP_PN_LEN 6
  33
  34 struct rtllib_ccmp_data {
  35         u8 key[CCMP_TK_LEN];
  36         int key_set;
  37
  38         u8 tx_pn[CCMP_PN_LEN];
  39         u8 rx_pn[CCMP_PN_LEN];
  40
  41         u32 dot11RSNAStatsCCMPFormatErrors;
  42         u32 dot11RSNAStatsCCMPReplays;
  43         u32 dot11RSNAStatsCCMPDecryptErrors;
  44
  45         int key_idx;
  46
  47         struct crypto_tfm *tfm;
  48
  49         /* scratch buffers for virt_to_page() (crypto API) */
  50         u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
  51                 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
  52         u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
  53 };
  54
  55 static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
  56                              const u8 pt[16], u8 ct[16])
  57 {
  58         crypto_cipher_encrypt_one((void *)tfm, ct, pt);
  59 }
  60
  61 static void *rtllib_ccmp_init(int key_idx)
  62 {
  63         struct rtllib_ccmp_data *priv;
  64
  65         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  66         if (priv == NULL)
  67                 goto fail;
  68         priv->key_idx = key_idx;
  69
  70         priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
  71         if (IS_ERR(priv->tfm)) {
  72                 pr_debug("Could not allocate crypto API aes\n");
  73                 priv->tfm = NULL;
  74                 goto fail;
  75         }
  76         return priv;
  77
  78 fail:
  79         if (priv) {
  80                 if (priv->tfm)
  81                         crypto_free_cipher((void *)priv->tfm);
  82                 kfree(priv);
  83         }
  84
  85         return NULL;
  86 }
  87
  88
  89 static void rtllib_ccmp_deinit(void *priv)
  90 {
  91         struct rtllib_ccmp_data *_priv = priv;
  92
  93         if (_priv && _priv->tfm)
  94                 crypto_free_cipher((void *)_priv->tfm);
  95         kfree(priv);
  96 }
  97
  98
  99 static inline void xor_block(u8 *b, u8 *a, size_t len)
 100 {
 101         int i;
 102
 103         for (i = 0; i < len; i++)
 104                 b[i] ^= a[i];
 105 }
 106
 107
 108
 109 static void ccmp_init_blocks(struct crypto_tfm *tfm,
 110                              struct rtllib_hdr_4addr *hdr,
 111                              u8 *pn, size_t dlen, u8 *b0, u8 *auth,
 112                              u8 *s0)
 113 {
 114         u8 *pos, qc = 0;
 115         size_t aad_len;
 116         u16 fc;
 117         int a4_included, qc_included;
 118         u8 aad[2 * AES_BLOCK_LEN];
 119
 120         fc = le16_to_cpu(hdr->frame_ctl);
 121         a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
 122                        (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
 123
 124         qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
 125                        (WLAN_FC_GET_STYPE(fc) & 0x80));
 126         aad_len = 22;
 127         if (a4_included)
 128                 aad_len += 6;
 129         if (qc_included) {
 130                 pos = (u8 *) &hdr->addr4;
 131                 if (a4_included)
 132                         pos += 6;
 133                 qc = *pos & 0x0f;
 134                 aad_len += 2;
 135         }
 136         /* CCM Initial Block:
 137          * Flag (Include authentication header, M=3 (8-octet MIC),
 138          *       L=1 (2-octet Dlen))
 139          * Nonce: 0x00 | A2 | PN
 140          * Dlen
 141          */
 142         b0[0] = 0x59;
 143         b0[1] = qc;
 144         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
 145         memcpy(b0 + 8, pn, CCMP_PN_LEN);
 146         b0[14] = (dlen >> 8) & 0xff;
 147         b0[15] = dlen & 0xff;
 148
 149         /* AAD:
 150          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 151          * A1 | A2 | A3
 152          * SC with bits 4..15 (seq#) masked to zero
 153          * A4 (if present)
 154          * QC (if present)
 155          */
 156         pos = (u8 *) hdr;
 157         aad[0] = 0; /* aad_len >> 8 */
 158         aad[1] = aad_len & 0xff;
 159         aad[2] = pos[0] & 0x8f;
 160         aad[3] = pos[1] & 0xc7;
 161         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
 162         pos = (u8 *) &hdr->seq_ctl;
 163         aad[22] = pos[0] & 0x0f;
 164         aad[23] = 0; /* all bits masked */
 165         memset(aad + 24, 0, 8);
 166         if (a4_included)
 167                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
 168         if (qc_included) {
 169                 aad[a4_included ? 30 : 24] = qc;
 170                 /* rest of QC masked */
 171         }
 172
 173         /* Start with the first block and AAD */
 174         rtllib_ccmp_aes_encrypt(tfm, b0, auth);
 175         xor_block(auth, aad, AES_BLOCK_LEN);
 176         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 177         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 178         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 179         b0[0] &= 0x07;
 180         b0[14] = b0[15] = 0;
 181         rtllib_ccmp_aes_encrypt(tfm, b0, s0);
 182 }
 183
 184
 185
 186 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 187 {
 188         struct rtllib_ccmp_data *key = priv;
 189         int data_len, i;
 190         u8 *pos;
 191         struct rtllib_hdr_4addr *hdr;
 192         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 193                                     MAX_DEV_ADDR_SIZE);
 194         if (skb_headroom(skb) < CCMP_HDR_LEN ||
 195             skb_tailroom(skb) < CCMP_MIC_LEN ||
 196             skb->len < hdr_len)
 197                 return -1;
 198
 199         data_len = skb->len - hdr_len;
 200         pos = skb_push(skb, CCMP_HDR_LEN);
 201         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 202         pos += hdr_len;
 203
 204         i = CCMP_PN_LEN - 1;
 205         while (i >= 0) {
 206                 key->tx_pn[i]++;
 207                 if (key->tx_pn[i] != 0)
 208                         break;
 209                 i--;
 210         }
 211
 212         *pos++ = key->tx_pn[5];
 213         *pos++ = key->tx_pn[4];
 214         *pos++ = 0;
 215         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 216         *pos++ = key->tx_pn[3];
 217         *pos++ = key->tx_pn[2];
 218         *pos++ = key->tx_pn[1];
 219         *pos++ = key->tx_pn[0];
 220
 221
 222         hdr = (struct rtllib_hdr_4addr *) skb->data;
 223         if (!tcb_desc->bHwSec) {
 224                 int blocks, last, len;
 225                 u8 *mic;
 226                 u8 *b0 = key->tx_b0;
 227                 u8 *b = key->tx_b;
 228                 u8 *e = key->tx_e;
 229                 u8 *s0 = key->tx_s0;
 230
 231                 mic = skb_put(skb, CCMP_MIC_LEN);
 232
 233                 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
 234                                  b0, b, s0);
 235
 236                 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
 237                 last = data_len % AES_BLOCK_LEN;
 238
 239                 for (i = 1; i <= blocks; i++) {
 240                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 241                         /* Authentication */
 242                         xor_block(b, pos, len);
 243                         rtllib_ccmp_aes_encrypt(key->tfm, b, b);
 244                         /* Encryption, with counter */
 245                         b0[14] = (i >> 8) & 0xff;
 246                         b0[15] = i & 0xff;
 247                         rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
 248                         xor_block(pos, e, len);
 249                         pos += len;
 250                 }
 251
 252                 for (i = 0; i < CCMP_MIC_LEN; i++)
 253                         mic[i] = b[i] ^ s0[i];
 254         }
 255         return 0;
 256 }
 257
 258
 259 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 260 {
 261         struct rtllib_ccmp_data *key = priv;
 262         u8 keyidx, *pos;
 263         struct rtllib_hdr_4addr *hdr;
 264         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 265                                     MAX_DEV_ADDR_SIZE);
 266         u8 pn[6];
 267
 268         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 269                 key->dot11RSNAStatsCCMPFormatErrors++;
 270                 return -1;
 271         }
 272
 273         hdr = (struct rtllib_hdr_4addr *) skb->data;
 274         pos = skb->data + hdr_len;
 275         keyidx = pos[3];
 276         if (!(keyidx & (1 << 5))) {
 277                 if (net_ratelimit()) {
 278                         pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
 279                                  hdr->addr2);
 280                 }
 281                 key->dot11RSNAStatsCCMPFormatErrors++;
 282                 return -2;
 283         }
 284         keyidx >>= 6;
 285         if (key->key_idx != keyidx) {
 286                 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
 287                          key->key_idx, keyidx, priv);
 288                 return -6;
 289         }
 290         if (!key->key_set) {
 291                 if (net_ratelimit()) {
 292                         pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
 293                                  hdr->addr2, keyidx);
 294                 }
 295                 return -3;
 296         }
 297
 298         pn[0] = pos[7];
 299         pn[1] = pos[6];
 300         pn[2] = pos[5];
 301         pn[3] = pos[4];
 302         pn[4] = pos[1];
 303         pn[5] = pos[0];
 304         pos += 8;
 305         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 306                 key->dot11RSNAStatsCCMPReplays++;
 307                 return -4;
 308         }
 309         if (!tcb_desc->bHwSec) {
 310                 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
 311                                   CCMP_MIC_LEN;
 312                 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
 313                 u8 *b0 = key->rx_b0;
 314                 u8 *b = key->rx_b;
 315                 u8 *a = key->rx_a;
 316                 int i, blocks, last, len;
 317
 318
 319                 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
 320                 xor_block(mic, b, CCMP_MIC_LEN);
 321
 322                 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
 323                 last = data_len % AES_BLOCK_LEN;
 324
 325                 for (i = 1; i <= blocks; i++) {
 326                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 327                         /* Decrypt, with counter */
 328                         b0[14] = (i >> 8) & 0xff;
 329                         b0[15] = i & 0xff;
 330                         rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
 331                         xor_block(pos, b, len);
 332                         /* Authentication */
 333                         xor_block(a, pos, len);
 334                         rtllib_ccmp_aes_encrypt(key->tfm, a, a);
 335                         pos += len;
 336                 }
 337
 338                 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
 339                         if (net_ratelimit()) {
 340                                 pr_debug("CCMP: decrypt failed: STA= %pM\n",
 341                                          hdr->addr2);
 342                         }
 343                         key->dot11RSNAStatsCCMPDecryptErrors++;
 344                         return -5;
 345                 }
 346
 347                 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 348         }
 349         /* Remove hdr and MIC */
 350         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 351         skb_pull(skb, CCMP_HDR_LEN);
 352         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 353
 354         return keyidx;
 355 }
 356
 357
 358 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 359 {
 360         struct rtllib_ccmp_data *data = priv;
 361         int keyidx;
 362         struct crypto_tfm *tfm = data->tfm;
 363
 364         keyidx = data->key_idx;
 365         memset(data, 0, sizeof(*data));
 366         data->key_idx = keyidx;
 367         data->tfm = tfm;
 368         if (len == CCMP_TK_LEN) {
 369                 memcpy(data->key, key, CCMP_TK_LEN);
 370                 data->key_set = 1;
 371                 if (seq) {
 372                         data->rx_pn[0] = seq[5];
 373                         data->rx_pn[1] = seq[4];
 374                         data->rx_pn[2] = seq[3];
 375                         data->rx_pn[3] = seq[2];
 376                         data->rx_pn[4] = seq[1];
 377                         data->rx_pn[5] = seq[0];
 378                 }
 379                 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
 380         } else if (len == 0)
 381                 data->key_set = 0;
 382         else
 383                 return -1;
 384
 385         return 0;
 386 }
 387
 388
 389 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 390 {
 391         struct rtllib_ccmp_data *data = priv;
 392
 393         if (len < CCMP_TK_LEN)
 394                 return -1;
 395
 396         if (!data->key_set)
 397                 return 0;
 398         memcpy(key, data->key, CCMP_TK_LEN);
 399
 400         if (seq) {
 401                 seq[0] = data->tx_pn[5];
 402                 seq[1] = data->tx_pn[4];
 403                 seq[2] = data->tx_pn[3];
 404                 seq[3] = data->tx_pn[2];
 405                 seq[4] = data->tx_pn[1];
 406                 seq[5] = data->tx_pn[0];
 407         }
 408
 409         return CCMP_TK_LEN;
 410 }
 411
 412
 413 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
 414 {
 415         struct rtllib_ccmp_data *ccmp = priv;
 416
 417         seq_printf(m,
 418                    "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
 419                    ccmp->key_idx, ccmp->key_set,
 420                    ccmp->tx_pn, ccmp->rx_pn,
 421                    ccmp->dot11RSNAStatsCCMPFormatErrors,
 422                    ccmp->dot11RSNAStatsCCMPReplays,
 423                    ccmp->dot11RSNAStatsCCMPDecryptErrors);
 424 }
 425
 426 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
 427         .name                   = "R-CCMP",
 428         .init                   = rtllib_ccmp_init,
 429         .deinit                 = rtllib_ccmp_deinit,
 430         .encrypt_mpdu           = rtllib_ccmp_encrypt,
 431         .decrypt_mpdu           = rtllib_ccmp_decrypt,
 432         .encrypt_msdu           = NULL,
 433         .decrypt_msdu           = NULL,
 434         .set_key                = rtllib_ccmp_set_key,
 435         .get_key                = rtllib_ccmp_get_key,
 436         .print_stats            = rtllib_ccmp_print_stats,
 437         .extra_mpdu_prefix_len = CCMP_HDR_LEN,
 438         .extra_mpdu_postfix_len = CCMP_MIC_LEN,
 439         .owner                  = THIS_MODULE,
 440 };
 441
 442
 443 static int __init rtllib_crypto_ccmp_init(void)
 444 {
 445         return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
 446 }
 447
 448
 449 static void __exit rtllib_crypto_ccmp_exit(void)
 450 {
 451         lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
 452 }
 453
 454 module_init(rtllib_crypto_ccmp_init);
 455 module_exit(rtllib_crypto_ccmp_exit);
 456
 457 MODULE_LICENSE("GPL");