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                 printk(KERN_DEBUG "rtllib_crypt_ccmp: could not allocate "
  73                        "crypto API aes\n");
  74                 priv->tfm = NULL;
  75                 goto fail;
  76         }
  77         return priv;
  78
  79 fail:
  80         if (priv) {
  81                 if (priv->tfm)
  82                         crypto_free_cipher((void *)priv->tfm);
  83                 kfree(priv);
  84         }
  85
  86         return NULL;
  87 }
  88
  89
  90 static void rtllib_ccmp_deinit(void *priv)
  91 {
  92         struct rtllib_ccmp_data *_priv = priv;
  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         for (i = 0; i < len; i++)
 103                 b[i] ^= a[i];
 104 }
 105
 106
 107
 108 static void ccmp_init_blocks(struct crypto_tfm *tfm,
 109                              struct rtllib_hdr_4addr *hdr,
 110                              u8 *pn, size_t dlen, u8 *b0, u8 *auth,
 111                              u8 *s0)
 112 {
 113         u8 *pos, qc = 0;
 114         size_t aad_len;
 115         u16 fc;
 116         int a4_included, qc_included;
 117         u8 aad[2 * AES_BLOCK_LEN];
 118
 119         fc = le16_to_cpu(hdr->frame_ctl);
 120         a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
 121                        (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
 122         /*
 123         qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
 124                        (WLAN_FC_GET_STYPE(fc) & 0x08));
 125         */
 126         qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
 127                        (WLAN_FC_GET_STYPE(fc) & 0x80));
 128         aad_len = 22;
 129         if (a4_included)
 130                 aad_len += 6;
 131         if (qc_included) {
 132                 pos = (u8 *) &hdr->addr4;
 133                 if (a4_included)
 134                         pos += 6;
 135                 qc = *pos & 0x0f;
 136                 aad_len += 2;
 137         }
 138         /* CCM Initial Block:
 139          * Flag (Include authentication header, M=3 (8-octet MIC),
 140          *       L=1 (2-octet Dlen))
 141          * Nonce: 0x00 | A2 | PN
 142          * Dlen */
 143         b0[0] = 0x59;
 144         b0[1] = qc;
 145         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
 146         memcpy(b0 + 8, pn, CCMP_PN_LEN);
 147         b0[14] = (dlen >> 8) & 0xff;
 148         b0[15] = dlen & 0xff;
 149
 150         /* AAD:
 151          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 152          * A1 | A2 | A3
 153          * SC with bits 4..15 (seq#) masked to zero
 154          * A4 (if present)
 155          * QC (if present)
 156          */
 157         pos = (u8 *) hdr;
 158         aad[0] = 0; /* aad_len >> 8 */
 159         aad[1] = aad_len & 0xff;
 160         aad[2] = pos[0] & 0x8f;
 161         aad[3] = pos[1] & 0xc7;
 162         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
 163         pos = (u8 *) &hdr->seq_ctl;
 164         aad[22] = pos[0] & 0x0f;
 165         aad[23] = 0; /* all bits masked */
 166         memset(aad + 24, 0, 8);
 167         if (a4_included)
 168                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
 169         if (qc_included) {
 170                 aad[a4_included ? 30 : 24] = qc;
 171                 /* rest of QC masked */
 172         }
 173
 174         /* Start with the first block and AAD */
 175         rtllib_ccmp_aes_encrypt(tfm, b0, auth);
 176         xor_block(auth, aad, AES_BLOCK_LEN);
 177         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 178         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 179         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 180         b0[0] &= 0x07;
 181         b0[14] = b0[15] = 0;
 182         rtllib_ccmp_aes_encrypt(tfm, b0, s0);
 183 }
 184
 185
 186
 187 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 188 {
 189         struct rtllib_ccmp_data *key = priv;
 190         int data_len, i;
 191         u8 *pos;
 192         struct rtllib_hdr_4addr *hdr;
 193         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 194                                     MAX_DEV_ADDR_SIZE);
 195         if (skb_headroom(skb) < CCMP_HDR_LEN ||
 196             skb_tailroom(skb) < CCMP_MIC_LEN ||
 197             skb->len < hdr_len)
 198                 return -1;
 199
 200         data_len = skb->len - hdr_len;
 201         pos = skb_push(skb, CCMP_HDR_LEN);
 202         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 203         pos += hdr_len;
 204
 205         i = CCMP_PN_LEN - 1;
 206         while (i >= 0) {
 207                 key->tx_pn[i]++;
 208                 if (key->tx_pn[i] != 0)
 209                         break;
 210                 i--;
 211         }
 212
 213         *pos++ = key->tx_pn[5];
 214         *pos++ = key->tx_pn[4];
 215         *pos++ = 0;
 216         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 217         *pos++ = key->tx_pn[3];
 218         *pos++ = key->tx_pn[2];
 219         *pos++ = key->tx_pn[1];
 220         *pos++ = key->tx_pn[0];
 221
 222
 223         hdr = (struct rtllib_hdr_4addr *) skb->data;
 224         if (!tcb_desc->bHwSec) {
 225                 int blocks, last, len;
 226                 u8 *mic;
 227                 u8 *b0 = key->tx_b0;
 228                 u8 *b = key->tx_b;
 229                 u8 *e = key->tx_e;
 230                 u8 *s0 = key->tx_s0;
 231
 232                 mic = skb_put(skb, CCMP_MIC_LEN);
 233
 234                 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
 235                                  b0, b, s0);
 236
 237                 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 238                 last = data_len % AES_BLOCK_LEN;
 239
 240                 for (i = 1; i <= blocks; i++) {
 241                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 242                         /* Authentication */
 243                         xor_block(b, pos, len);
 244                         rtllib_ccmp_aes_encrypt(key->tfm, b, b);
 245                         /* Encryption, with counter */
 246                         b0[14] = (i >> 8) & 0xff;
 247                         b0[15] = i & 0xff;
 248                         rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
 249                         xor_block(pos, e, len);
 250                         pos += len;
 251                 }
 252
 253                 for (i = 0; i < CCMP_MIC_LEN; i++)
 254                         mic[i] = b[i] ^ s0[i];
 255         }
 256         return 0;
 257 }
 258
 259
 260 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 261 {
 262         struct rtllib_ccmp_data *key = priv;
 263         u8 keyidx, *pos;
 264         struct rtllib_hdr_4addr *hdr;
 265         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 266                                     MAX_DEV_ADDR_SIZE);
 267         u8 pn[6];
 268
 269         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 270                 key->dot11RSNAStatsCCMPFormatErrors++;
 271                 return -1;
 272         }
 273
 274         hdr = (struct rtllib_hdr_4addr *) skb->data;
 275         pos = skb->data + hdr_len;
 276         keyidx = pos[3];
 277         if (!(keyidx & (1 << 5))) {
 278                 if (net_ratelimit()) {
 279                         printk(KERN_DEBUG "CCMP: received packet without ExtIV"
 280                                " flag from %pM\n", hdr->addr2);
 281                 }
 282                 key->dot11RSNAStatsCCMPFormatErrors++;
 283                 return -2;
 284         }
 285         keyidx >>= 6;
 286         if (key->key_idx != keyidx) {
 287                 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
 288                        "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
 289                 return -6;
 290         }
 291         if (!key->key_set) {
 292                 if (net_ratelimit()) {
 293                         printk(KERN_DEBUG "CCMP: received packet from %pM"
 294                                " with keyid=%d that does not have a configured"
 295                                " key\n", hdr->addr2, keyidx);
 296                 }
 297                 return -3;
 298         }
 299
 300         pn[0] = pos[7];
 301         pn[1] = pos[6];
 302         pn[2] = pos[5];
 303         pn[3] = pos[4];
 304         pn[4] = pos[1];
 305         pn[5] = pos[0];
 306         pos += 8;
 307         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 308                 key->dot11RSNAStatsCCMPReplays++;
 309                 return -4;
 310         }
 311         if (!tcb_desc->bHwSec) {
 312                 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
 313                                   CCMP_MIC_LEN;
 314                 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
 315                 u8 *b0 = key->rx_b0;
 316                 u8 *b = key->rx_b;
 317                 u8 *a = key->rx_a;
 318                 int i, blocks, last, len;
 319
 320
 321                 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
 322                 xor_block(mic, b, CCMP_MIC_LEN);
 323
 324                 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 325                 last = data_len % AES_BLOCK_LEN;
 326
 327                 for (i = 1; i <= blocks; i++) {
 328                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 329                         /* Decrypt, with counter */
 330                         b0[14] = (i >> 8) & 0xff;
 331                         b0[15] = i & 0xff;
 332                         rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
 333                         xor_block(pos, b, len);
 334                         /* Authentication */
 335                         xor_block(a, pos, len);
 336                         rtllib_ccmp_aes_encrypt(key->tfm, a, a);
 337                         pos += len;
 338                 }
 339
 340                 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
 341                         if (net_ratelimit()) {
 342                                 printk(KERN_DEBUG "CCMP: decrypt failed: STA="
 343                                 " %pM\n", hdr->addr2);
 344                         }
 345                         key->dot11RSNAStatsCCMPDecryptErrors++;
 346                         return -5;
 347                 }
 348
 349                 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 350         }
 351         /* Remove hdr and MIC */
 352         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 353         skb_pull(skb, CCMP_HDR_LEN);
 354         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 355
 356         return keyidx;
 357 }
 358
 359
 360 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 361 {
 362         struct rtllib_ccmp_data *data = priv;
 363         int keyidx;
 364         struct crypto_tfm *tfm = data->tfm;
 365
 366         keyidx = data->key_idx;
 367         memset(data, 0, sizeof(*data));
 368         data->key_idx = keyidx;
 369         data->tfm = tfm;
 370         if (len == CCMP_TK_LEN) {
 371                 memcpy(data->key, key, CCMP_TK_LEN);
 372                 data->key_set = 1;
 373                 if (seq) {
 374                         data->rx_pn[0] = seq[5];
 375                         data->rx_pn[1] = seq[4];
 376                         data->rx_pn[2] = seq[3];
 377                         data->rx_pn[3] = seq[2];
 378                         data->rx_pn[4] = seq[1];
 379                         data->rx_pn[5] = seq[0];
 380                 }
 381                 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
 382         } else if (len == 0)
 383                 data->key_set = 0;
 384         else
 385                 return -1;
 386
 387         return 0;
 388 }
 389
 390
 391 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 392 {
 393         struct rtllib_ccmp_data *data = priv;
 394
 395         if (len < CCMP_TK_LEN)
 396                 return -1;
 397
 398         if (!data->key_set)
 399                 return 0;
 400         memcpy(key, data->key, CCMP_TK_LEN);
 401
 402         if (seq) {
 403                 seq[0] = data->tx_pn[5];
 404                 seq[1] = data->tx_pn[4];
 405                 seq[2] = data->tx_pn[3];
 406                 seq[3] = data->tx_pn[2];
 407                 seq[4] = data->tx_pn[1];
 408                 seq[5] = data->tx_pn[0];
 409         }
 410
 411         return CCMP_TK_LEN;
 412 }
 413
 414
 415 static char *rtllib_ccmp_print_stats(char *p, void *priv)
 416 {
 417         struct rtllib_ccmp_data *ccmp = priv;
 418         p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
 419                      "tx_pn=%pM rx_pn=%pM "
 420                      "format_errors=%d replays=%d decrypt_errors=%d\n",
 421                      ccmp->key_idx, ccmp->key_set,
 422                      ccmp->tx_pn, ccmp->rx_pn,
 423                      ccmp->dot11RSNAStatsCCMPFormatErrors,
 424                      ccmp->dot11RSNAStatsCCMPReplays,
 425                      ccmp->dot11RSNAStatsCCMPDecryptErrors);
 426
 427         return p;
 428 }
 429
 430 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
 431         .name                   = "R-CCMP",
 432         .init                   = rtllib_ccmp_init,
 433         .deinit                 = rtllib_ccmp_deinit,
 434         .encrypt_mpdu           = rtllib_ccmp_encrypt,
 435         .decrypt_mpdu           = rtllib_ccmp_decrypt,
 436         .encrypt_msdu           = NULL,
 437         .decrypt_msdu           = NULL,
 438         .set_key                = rtllib_ccmp_set_key,
 439         .get_key                = rtllib_ccmp_get_key,
 440         .print_stats            = rtllib_ccmp_print_stats,
 441         .extra_mpdu_prefix_len = CCMP_HDR_LEN,
 442         .extra_mpdu_postfix_len = CCMP_MIC_LEN,
 443         .owner                  = THIS_MODULE,
 444 };
 445
 446
 447 int __init rtllib_crypto_ccmp_init(void)
 448 {
 449         return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
 450 }
 451
 452
 453 void __exit rtllib_crypto_ccmp_exit(void)
 454 {
 455         lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
 456 }
 457
 458 module_init(rtllib_crypto_ccmp_init);
 459 module_exit(rtllib_crypto_ccmp_exit);
 460
 461 MODULE_LICENSE("GPL");