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/version.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/random.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/if_ether.h>
  20 #include <linux/if_arp.h>
  21 #include <linux/string.h>
  22 #include <linux/wireless.h>
  23 #include "rtllib.h"
  24
  25 #include <linux/crypto.h>
  26
  27 #include <linux/scatterlist.h>
  28
  29 #define AES_BLOCK_LEN 16
  30 #define CCMP_HDR_LEN 8
  31 #define CCMP_MIC_LEN 8
  32 #define CCMP_TK_LEN 16
  33 #define CCMP_PN_LEN 6
  34
  35 struct rtllib_ccmp_data {
  36         u8 key[CCMP_TK_LEN];
  37         int key_set;
  38
  39         u8 tx_pn[CCMP_PN_LEN];
  40         u8 rx_pn[CCMP_PN_LEN];
  41
  42         u32 dot11RSNAStatsCCMPFormatErrors;
  43         u32 dot11RSNAStatsCCMPReplays;
  44         u32 dot11RSNAStatsCCMPDecryptErrors;
  45
  46         int key_idx;
  47
  48         struct crypto_tfm *tfm;
  49
  50         /* scratch buffers for virt_to_page() (crypto API) */
  51         u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
  52                 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
  53         u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
  54 };
  55
  56 static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
  57                              const u8 pt[16], u8 ct[16])
  58 {
  59         crypto_cipher_encrypt_one((void *)tfm, ct, pt);
  60 }
  61
  62 static void *rtllib_ccmp_init(int key_idx)
  63 {
  64         struct rtllib_ccmp_data *priv;
  65
  66         priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
  67         if (priv == NULL)
  68                 goto fail;
  69         memset(priv, 0, sizeof(*priv));
  70         priv->key_idx = key_idx;
  71
  72         priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
  73         if (IS_ERR(priv->tfm)) {
  74                 printk(KERN_DEBUG "rtllib_crypt_ccmp: could not allocate "
  75                        "crypto API aes\n");
  76                 priv->tfm = NULL;
  77                 goto fail;
  78         }
  79         return priv;
  80
  81 fail:
  82         if (priv) {
  83                 if (priv->tfm)
  84                         crypto_free_cipher((void *)priv->tfm);
  85                 kfree(priv);
  86         }
  87
  88         return NULL;
  89 }
  90
  91
  92 static void rtllib_ccmp_deinit(void *priv)
  93 {
  94         struct rtllib_ccmp_data *_priv = priv;
  95         if (_priv && _priv->tfm)
  96                 crypto_free_cipher((void *)_priv->tfm);
  97         kfree(priv);
  98 }
  99
 100
 101 static inline void xor_block(u8 *b, u8 *a, size_t len)
 102 {
 103         int i;
 104         for (i = 0; i < len; i++)
 105                 b[i] ^= a[i];
 106 }
 107
 108
 109
 110 static void ccmp_init_blocks(struct crypto_tfm *tfm,
 111                              struct rtllib_hdr_4addr *hdr,
 112                              u8 *pn, size_t dlen, u8 *b0, u8 *auth,
 113                              u8 *s0)
 114 {
 115         u8 *pos, qc = 0;
 116         size_t aad_len;
 117         u16 fc;
 118         int a4_included, qc_included;
 119         u8 aad[2 * AES_BLOCK_LEN];
 120
 121         fc = le16_to_cpu(hdr->frame_ctl);
 122         a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
 123                        (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
 124         /*
 125         qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
 126                        (WLAN_FC_GET_STYPE(fc) & 0x08));
 127         */
 128         qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
 129                        (WLAN_FC_GET_STYPE(fc) & 0x80));
 130         aad_len = 22;
 131         if (a4_included)
 132                 aad_len += 6;
 133         if (qc_included) {
 134                 pos = (u8 *) &hdr->addr4;
 135                 if (a4_included)
 136                         pos += 6;
 137                 qc = *pos & 0x0f;
 138                 aad_len += 2;
 139         }
 140         /* CCM Initial Block:
 141          * Flag (Include authentication header, M=3 (8-octet MIC),
 142          *       L=1 (2-octet Dlen))
 143          * Nonce: 0x00 | A2 | PN
 144          * Dlen */
 145         b0[0] = 0x59;
 146         b0[1] = qc;
 147         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
 148         memcpy(b0 + 8, pn, CCMP_PN_LEN);
 149         b0[14] = (dlen >> 8) & 0xff;
 150         b0[15] = dlen & 0xff;
 151
 152         /* AAD:
 153          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 154          * A1 | A2 | A3
 155          * SC with bits 4..15 (seq#) masked to zero
 156          * A4 (if present)
 157          * QC (if present)
 158          */
 159         pos = (u8 *) hdr;
 160         aad[0] = 0; /* aad_len >> 8 */
 161         aad[1] = aad_len & 0xff;
 162         aad[2] = pos[0] & 0x8f;
 163         aad[3] = pos[1] & 0xc7;
 164         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
 165         pos = (u8 *) &hdr->seq_ctl;
 166         aad[22] = pos[0] & 0x0f;
 167         aad[23] = 0; /* all bits masked */
 168         memset(aad + 24, 0, 8);
 169         if (a4_included)
 170                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
 171         if (qc_included) {
 172                 aad[a4_included ? 30 : 24] = qc;
 173                 /* rest of QC masked */
 174         }
 175
 176         /* Start with the first block and AAD */
 177         rtllib_ccmp_aes_encrypt(tfm, b0, auth);
 178         xor_block(auth, aad, AES_BLOCK_LEN);
 179         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 180         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 181         rtllib_ccmp_aes_encrypt(tfm, auth, auth);
 182         b0[0] &= 0x07;
 183         b0[14] = b0[15] = 0;
 184         rtllib_ccmp_aes_encrypt(tfm, b0, s0);
 185 }
 186
 187
 188
 189 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 190 {
 191         struct rtllib_ccmp_data *key = priv;
 192         int data_len, i;
 193         u8 *pos;
 194         struct rtllib_hdr_4addr *hdr;
 195         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 196                                     MAX_DEV_ADDR_SIZE);
 197         if (skb_headroom(skb) < CCMP_HDR_LEN ||
 198             skb_tailroom(skb) < CCMP_MIC_LEN ||
 199             skb->len < hdr_len)
 200                 return -1;
 201
 202         data_len = skb->len - hdr_len;
 203         pos = skb_push(skb, CCMP_HDR_LEN);
 204         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 205         pos += hdr_len;
 206
 207         i = CCMP_PN_LEN - 1;
 208         while (i >= 0) {
 209                 key->tx_pn[i]++;
 210                 if (key->tx_pn[i] != 0)
 211                         break;
 212                 i--;
 213         }
 214
 215         *pos++ = key->tx_pn[5];
 216         *pos++ = key->tx_pn[4];
 217         *pos++ = 0;
 218         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 219         *pos++ = key->tx_pn[3];
 220         *pos++ = key->tx_pn[2];
 221         *pos++ = key->tx_pn[1];
 222         *pos++ = key->tx_pn[0];
 223
 224
 225         hdr = (struct rtllib_hdr_4addr *) skb->data;
 226         if (!tcb_desc->bHwSec) {
 227                 int blocks, last, len;
 228                 u8 *mic;
 229                 u8 *b0 = key->tx_b0;
 230                 u8 *b = key->tx_b;
 231                 u8 *e = key->tx_e;
 232                 u8 *s0 = key->tx_s0;
 233
 234                 mic = skb_put(skb, CCMP_MIC_LEN);
 235
 236                 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
 237                                  b0, b, s0);
 238
 239                 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 240                 last = data_len % AES_BLOCK_LEN;
 241
 242                 for (i = 1; i <= blocks; i++) {
 243                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 244                         /* Authentication */
 245                         xor_block(b, pos, len);
 246                         rtllib_ccmp_aes_encrypt(key->tfm, b, b);
 247                         /* Encryption, with counter */
 248                         b0[14] = (i >> 8) & 0xff;
 249                         b0[15] = i & 0xff;
 250                         rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
 251                         xor_block(pos, e, len);
 252                         pos += len;
 253                 }
 254
 255                 for (i = 0; i < CCMP_MIC_LEN; i++)
 256                         mic[i] = b[i] ^ s0[i];
 257         }
 258         return 0;
 259 }
 260
 261
 262 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 263 {
 264         struct rtllib_ccmp_data *key = priv;
 265         u8 keyidx, *pos;
 266         struct rtllib_hdr_4addr *hdr;
 267         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 268                                     MAX_DEV_ADDR_SIZE);
 269         u8 pn[6];
 270
 271         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 272                 key->dot11RSNAStatsCCMPFormatErrors++;
 273                 return -1;
 274         }
 275
 276         hdr = (struct rtllib_hdr_4addr *) skb->data;
 277         pos = skb->data + hdr_len;
 278         keyidx = pos[3];
 279         if (!(keyidx & (1 << 5))) {
 280                 if (net_ratelimit()) {
 281                         printk(KERN_DEBUG "CCMP: received packet without ExtIV"
 282                                " flag from %pM\n", hdr->addr2);
 283                 }
 284                 key->dot11RSNAStatsCCMPFormatErrors++;
 285                 return -2;
 286         }
 287         keyidx >>= 6;
 288         if (key->key_idx != keyidx) {
 289                 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
 290                        "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
 291                 return -6;
 292         }
 293         if (!key->key_set) {
 294                 if (net_ratelimit()) {
 295                         printk(KERN_DEBUG "CCMP: received packet from %pM"
 296                                " with keyid=%d that does not have a configured"
 297                                " key\n", hdr->addr2, keyidx);
 298                 }
 299                 return -3;
 300         }
 301
 302         pn[0] = pos[7];
 303         pn[1] = pos[6];
 304         pn[2] = pos[5];
 305         pn[3] = pos[4];
 306         pn[4] = pos[1];
 307         pn[5] = pos[0];
 308         pos += 8;
 309         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 310                 key->dot11RSNAStatsCCMPReplays++;
 311                 return -4;
 312         }
 313         if (!tcb_desc->bHwSec) {
 314                 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
 315                                   CCMP_MIC_LEN;
 316                 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
 317                 u8 *b0 = key->rx_b0;
 318                 u8 *b = key->rx_b;
 319                 u8 *a = key->rx_a;
 320                 int i, blocks, last, len;
 321
 322
 323                 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
 324                 xor_block(mic, b, CCMP_MIC_LEN);
 325
 326                 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 327                 last = data_len % AES_BLOCK_LEN;
 328
 329                 for (i = 1; i <= blocks; i++) {
 330                         len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 331                         /* Decrypt, with counter */
 332                         b0[14] = (i >> 8) & 0xff;
 333                         b0[15] = i & 0xff;
 334                         rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
 335                         xor_block(pos, b, len);
 336                         /* Authentication */
 337                         xor_block(a, pos, len);
 338                         rtllib_ccmp_aes_encrypt(key->tfm, a, a);
 339                         pos += len;
 340                 }
 341
 342                 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
 343                         if (net_ratelimit()) {
 344                                 printk(KERN_DEBUG "CCMP: decrypt failed: STA="
 345                                 " %pM\n", hdr->addr2);
 346                         }
 347                         key->dot11RSNAStatsCCMPDecryptErrors++;
 348                         return -5;
 349                 }
 350
 351                 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 352         }
 353         /* Remove hdr and MIC */
 354         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 355         skb_pull(skb, CCMP_HDR_LEN);
 356         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 357
 358         return keyidx;
 359 }
 360
 361
 362 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 363 {
 364         struct rtllib_ccmp_data *data = priv;
 365         int keyidx;
 366         struct crypto_tfm *tfm = data->tfm;
 367
 368         keyidx = data->key_idx;
 369         memset(data, 0, sizeof(*data));
 370         data->key_idx = keyidx;
 371         data->tfm = tfm;
 372         if (len == CCMP_TK_LEN) {
 373                 memcpy(data->key, key, CCMP_TK_LEN);
 374                 data->key_set = 1;
 375                 if (seq) {
 376                         data->rx_pn[0] = seq[5];
 377                         data->rx_pn[1] = seq[4];
 378                         data->rx_pn[2] = seq[3];
 379                         data->rx_pn[3] = seq[2];
 380                         data->rx_pn[4] = seq[1];
 381                         data->rx_pn[5] = seq[0];
 382                 }
 383                 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
 384         } else if (len == 0)
 385                 data->key_set = 0;
 386         else
 387                 return -1;
 388
 389         return 0;
 390 }
 391
 392
 393 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 394 {
 395         struct rtllib_ccmp_data *data = priv;
 396
 397         if (len < CCMP_TK_LEN)
 398                 return -1;
 399
 400         if (!data->key_set)
 401                 return 0;
 402         memcpy(key, data->key, CCMP_TK_LEN);
 403
 404         if (seq) {
 405                 seq[0] = data->tx_pn[5];
 406                 seq[1] = data->tx_pn[4];
 407                 seq[2] = data->tx_pn[3];
 408                 seq[3] = data->tx_pn[2];
 409                 seq[4] = data->tx_pn[1];
 410                 seq[5] = data->tx_pn[0];
 411         }
 412
 413         return CCMP_TK_LEN;
 414 }
 415
 416
 417 static char *rtllib_ccmp_print_stats(char *p, void *priv)
 418 {
 419         struct rtllib_ccmp_data *ccmp = priv;
 420         p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
 421                      "tx_pn=%pM rx_pn=%pM "
 422                      "format_errors=%d replays=%d decrypt_errors=%d\n",
 423                      ccmp->key_idx, ccmp->key_set,
 424                      ccmp->tx_pn, ccmp->rx_pn,
 425                      ccmp->dot11RSNAStatsCCMPFormatErrors,
 426                      ccmp->dot11RSNAStatsCCMPReplays,
 427                      ccmp->dot11RSNAStatsCCMPDecryptErrors);
 428
 429         return p;
 430 }
 431
 432 void rtllib_ccmp_null(void)
 433 {
 434         return;
 435 }
 436
 437 static struct rtllib_crypto_ops rtllib_crypt_ccmp = {
 438         .name                   = "CCMP",
 439         .init                   = rtllib_ccmp_init,
 440         .deinit                 = rtllib_ccmp_deinit,
 441         .encrypt_mpdu           = rtllib_ccmp_encrypt,
 442         .decrypt_mpdu           = rtllib_ccmp_decrypt,
 443         .encrypt_msdu           = NULL,
 444         .decrypt_msdu           = NULL,
 445         .set_key                = rtllib_ccmp_set_key,
 446         .get_key                = rtllib_ccmp_get_key,
 447         .print_stats            = rtllib_ccmp_print_stats,
 448         .extra_prefix_len       = CCMP_HDR_LEN,
 449         .extra_postfix_len      = CCMP_MIC_LEN,
 450         .owner                  = THIS_MODULE,
 451 };
 452
 453
 454 int __init rtllib_crypto_ccmp_init(void)
 455 {
 456         return rtllib_register_crypto_ops(&rtllib_crypt_ccmp);
 457 }
 458
 459
 460 void __exit rtllib_crypto_ccmp_exit(void)
 461 {
 462         rtllib_unregister_crypto_ops(&rtllib_crypt_ccmp);
 463 }