drivers/staging/rtl8192u/ieee80211/ieee80211_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
  23 #include "ieee80211.h"
  24
  25 #include <linux/crypto.h>
  26     #include <linux/scatterlist.h>
  27
  28 MODULE_AUTHOR("Jouni Malinen");
  29 MODULE_DESCRIPTION("Host AP crypt: CCMP");
  30 MODULE_LICENSE("GPL");
  31
  32 #define AES_BLOCK_LEN 16
  33 #define CCMP_HDR_LEN 8
  34 #define CCMP_MIC_LEN 8
  35 #define CCMP_TK_LEN 16
  36 #define CCMP_PN_LEN 6
  37
  38 struct ieee80211_ccmp_data {
  39         u8 key[CCMP_TK_LEN];
  40         int key_set;
  41
  42         u8 tx_pn[CCMP_PN_LEN];
  43         u8 rx_pn[CCMP_PN_LEN];
  44
  45         u32 dot11RSNAStatsCCMPFormatErrors;
  46         u32 dot11RSNAStatsCCMPReplays;
  47         u32 dot11RSNAStatsCCMPDecryptErrors;
  48
  49         int key_idx;
  50
  51         struct crypto_tfm *tfm;
  52
  53         /* scratch buffers for virt_to_page() (crypto API) */
  54         u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
  55                 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
  56         u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
  57 };
  58
  59 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
  60                              const u8 pt[16], u8 ct[16])
  61 {
  62         crypto_cipher_encrypt_one((void *)tfm, ct, pt);
  63 }
  64
  65 static void *ieee80211_ccmp_init(int key_idx)
  66 {
  67         struct ieee80211_ccmp_data *priv;
  68
  69         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  70         if (!priv)
  71                 goto fail;
  72         priv->key_idx = key_idx;
  73
  74         priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
  75         if (IS_ERR(priv->tfm)) {
  76                 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate crypto API aes\n");
  77                 priv->tfm = NULL;
  78                 goto fail;
  79         }
  80
  81         return priv;
  82
  83 fail:
  84         if (priv) {
  85                 if (priv->tfm)
  86                         crypto_free_cipher((void *)priv->tfm);
  87                 kfree(priv);
  88         }
  89
  90         return NULL;
  91 }
  92
  93 static void ieee80211_ccmp_deinit(void *priv)
  94 {
  95         struct ieee80211_ccmp_data *_priv = priv;
  96
  97         if (_priv && _priv->tfm)
  98                 crypto_free_cipher((void *)_priv->tfm);
  99         kfree(priv);
 100 }
 101
 102 static inline void xor_block(u8 *b, u8 *a, size_t len)
 103 {
 104         int i;
 105
 106         for (i = 0; i < len; i++)
 107                 b[i] ^= a[i];
 108 }
 109
 110 static void ccmp_init_blocks(struct crypto_tfm *tfm,
 111                              struct rtl_80211_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 & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
 123                        (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
 124         /* qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
 125          *             (WLAN_FC_GET_STYPE(fc) & 0x08));
 126          */
 127         /* fixed by David :2006.9.6 */
 128         qc_included = (WLAN_FC_GET_TYPE(fc) == IEEE80211_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          */
 146         b0[0] = 0x59;
 147         b0[1] = qc;
 148         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
 149         memcpy(b0 + 8, pn, CCMP_PN_LEN);
 150         b0[14] = (dlen >> 8) & 0xff;
 151         b0[15] = dlen & 0xff;
 152
 153         /* AAD:
 154          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 155          * A1 | A2 | A3
 156          * SC with bits 4..15 (seq#) masked to zero
 157          * A4 (if present)
 158          * QC (if present)
 159          */
 160         pos = (u8 *)hdr;
 161         aad[0] = 0; /* aad_len >> 8 */
 162         aad[1] = aad_len & 0xff;
 163         aad[2] = pos[0] & 0x8f;
 164         aad[3] = pos[1] & 0xc7;
 165         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
 166         pos = (u8 *)&hdr->seq_ctl;
 167         aad[22] = pos[0] & 0x0f;
 168         aad[23] = 0; /* all bits masked */
 169         memset(aad + 24, 0, 8);
 170         if (a4_included)
 171                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
 172         if (qc_included) {
 173                 aad[a4_included ? 30 : 24] = qc;
 174                 /* rest of QC masked */
 175         }
 176
 177         /* Start with the first block and AAD */
 178         ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
 179         xor_block(auth, aad, AES_BLOCK_LEN);
 180         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
 181         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 182         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
 183         b0[0] &= 0x07;
 184         b0[14] = 0;
 185         b0[15] = 0;
 186         ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
 187 }
 188
 189 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 190 {
 191         struct ieee80211_ccmp_data *key = priv;
 192         int data_len, i;
 193         u8 *pos;
 194         struct rtl_80211_hdr_4addr *hdr;
 195         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 196
 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         /* mic = skb_put(skb, CCMP_MIC_LEN); */
 207
 208         i = CCMP_PN_LEN - 1;
 209         while (i >= 0) {
 210                 key->tx_pn[i]++;
 211                 if (key->tx_pn[i] != 0)
 212                         break;
 213                 i--;
 214         }
 215
 216         *pos++ = key->tx_pn[5];
 217         *pos++ = key->tx_pn[4];
 218         *pos++ = 0;
 219         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 220         *pos++ = key->tx_pn[3];
 221         *pos++ = key->tx_pn[2];
 222         *pos++ = key->tx_pn[1];
 223         *pos++ = key->tx_pn[0];
 224
 225         hdr = (struct rtl_80211_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 is moved to here by john */
 235                 mic = skb_put(skb, CCMP_MIC_LEN);
 236
 237                 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
 238
 239                 blocks = DIV_ROUND_UP(data_len, 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                         ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
 247                         /* Encryption, with counter */
 248                         b0[14] = (i >> 8) & 0xff;
 249                         b0[15] = i & 0xff;
 250                         ieee80211_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 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 262 {
 263         struct ieee80211_ccmp_data *key = priv;
 264         u8 keyidx, *pos;
 265         struct rtl_80211_hdr_4addr *hdr;
 266         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 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 rtl_80211_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 flag from %pM\n",
 280                                 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 keyidx=%d priv=%p\n",
 288                         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 with keyid=%d that does not have a configured key\n",
 294                                 hdr->addr2, keyidx);
 295                 }
 296                 return -3;
 297         }
 298
 299         pn[0] = pos[7];
 300         pn[1] = pos[6];
 301         pn[2] = pos[5];
 302         pn[3] = pos[4];
 303         pn[4] = pos[1];
 304         pn[5] = pos[0];
 305         pos += 8;
 306
 307         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 308                 if (net_ratelimit()) {
 309                         printk(KERN_DEBUG "CCMP: replay detected: STA=%pM previous PN %pm received PN %pm\n",
 310                                hdr->addr2, key->rx_pn, pn);
 311                 }
 312                 key->dot11RSNAStatsCCMPReplays++;
 313                 return -4;
 314         }
 315         if (!tcb_desc->bHwSec) {
 316                 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
 317                 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
 318                 u8 *b0 = key->rx_b0;
 319                 u8 *b = key->rx_b;
 320                 u8 *a = key->rx_a;
 321                 int i, blocks, last, len;
 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 = DIV_ROUND_UP(data_len, 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                         ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
 335                         xor_block(pos, b, len);
 336                         /* Authentication */
 337                         xor_block(a, pos, len);
 338                         ieee80211_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=%pM\n",
 345                                         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 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 362 {
 363         struct ieee80211_ccmp_data *data = priv;
 364         int keyidx;
 365         struct crypto_tfm *tfm = data->tfm;
 366
 367         keyidx = data->key_idx;
 368         memset(data, 0, sizeof(*data));
 369         data->key_idx = keyidx;
 370         data->tfm = tfm;
 371         if (len == CCMP_TK_LEN) {
 372                 memcpy(data->key, key, CCMP_TK_LEN);
 373                 data->key_set = 1;
 374                 if (seq) {
 375                         data->rx_pn[0] = seq[5];
 376                         data->rx_pn[1] = seq[4];
 377                         data->rx_pn[2] = seq[3];
 378                         data->rx_pn[3] = seq[2];
 379                         data->rx_pn[4] = seq[1];
 380                         data->rx_pn[5] = seq[0];
 381                 }
 382                 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
 383         } else if (len == 0) {
 384                 data->key_set = 0;
 385         } else {
 386                 return -1;
 387         }
 388
 389         return 0;
 390 }
 391
 392 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 393 {
 394         struct ieee80211_ccmp_data *data = priv;
 395
 396         if (len < CCMP_TK_LEN)
 397                 return -1;
 398
 399         if (!data->key_set)
 400                 return 0;
 401         memcpy(key, data->key, CCMP_TK_LEN);
 402
 403         if (seq) {
 404                 seq[0] = data->tx_pn[5];
 405                 seq[1] = data->tx_pn[4];
 406                 seq[2] = data->tx_pn[3];
 407                 seq[3] = data->tx_pn[2];
 408                 seq[4] = data->tx_pn[1];
 409                 seq[5] = data->tx_pn[0];
 410         }
 411
 412         return CCMP_TK_LEN;
 413 }
 414
 415 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
 416 {
 417         struct ieee80211_ccmp_data *ccmp = priv;
 418
 419         p += sprintf(p, "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n",
 420                      ccmp->key_idx, ccmp->key_set,
 421                      ccmp->tx_pn, ccmp->rx_pn,
 422                      ccmp->dot11RSNAStatsCCMPFormatErrors,
 423                      ccmp->dot11RSNAStatsCCMPReplays,
 424                      ccmp->dot11RSNAStatsCCMPDecryptErrors);
 425
 426         return p;
 427 }
 428
 429 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
 430         .name                   = "CCMP",
 431         .init                   = ieee80211_ccmp_init,
 432         .deinit                 = ieee80211_ccmp_deinit,
 433         .encrypt_mpdu           = ieee80211_ccmp_encrypt,
 434         .decrypt_mpdu           = ieee80211_ccmp_decrypt,
 435         .encrypt_msdu           = NULL,
 436         .decrypt_msdu           = NULL,
 437         .set_key                = ieee80211_ccmp_set_key,
 438         .get_key                = ieee80211_ccmp_get_key,
 439         .print_stats            = ieee80211_ccmp_print_stats,
 440         .extra_prefix_len       = CCMP_HDR_LEN,
 441         .extra_postfix_len      = CCMP_MIC_LEN,
 442         .owner                  = THIS_MODULE,
 443 };
 444
 445 int __init ieee80211_crypto_ccmp_init(void)
 446 {
 447         return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
 448 }
 449
 450 void __exit ieee80211_crypto_ccmp_exit(void)
 451 {
 452         ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
 453 }