release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/staging/rtl8192e/ieee80211/ieee80211_crypt_wep.c

   1 /*
   2  * Host AP crypt: host-based WEP encryption implementation for Host AP driver
   3  *
   4  * Copyright (c) 2002-2004, 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/config.h>
  13 #include <linux/version.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/slab.h>
  17 #include <linux/random.h>
  18 #include <linux/skbuff.h>
  19 #include <asm/string.h>
  20
  21 #include "ieee80211.h"
  22
  23
  24 #include <linux/crypto.h>
  25
  26 #include <linux/scatterlist.h>
  27 #include <linux/crc32.h>
  28
  29 MODULE_AUTHOR("Jouni Malinen");
  30 MODULE_DESCRIPTION("Host AP crypt: WEP");
  31 MODULE_LICENSE("GPL");
  32 #ifndef OPENSUSE_SLED
  33 #define OPENSUSE_SLED 0
  34 #endif
  35
  36 struct prism2_wep_data {
  37         u32 iv;
  38 #define WEP_KEY_LEN 13
  39         u8 key[WEP_KEY_LEN + 1];
  40         u8 key_len;
  41         u8 key_idx;
  42         struct crypto_blkcipher *tx_tfm;
  43         struct crypto_blkcipher *rx_tfm;
  44 };
  45
  46
  47 static void * prism2_wep_init(int keyidx)
  48 {
  49         struct prism2_wep_data *priv;
  50
  51         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  52         if (priv == NULL)
  53                 goto fail;
  54         priv->key_idx = keyidx;
  55
  56         priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
  57         if (IS_ERR(priv->tx_tfm)) {
  58                 printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
  59                        "crypto API arc4\n");
  60                 priv->tx_tfm = NULL;
  61                 goto fail;
  62         }
  63         priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
  64         if (IS_ERR(priv->rx_tfm)) {
  65                 printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
  66                        "crypto API arc4\n");
  67                 priv->rx_tfm = NULL;
  68                 goto fail;
  69         }
  70
  71         /* start WEP IV from a random value */
  72         get_random_bytes(&priv->iv, 4);
  73
  74         return priv;
  75
  76 fail:
  77         if (priv) {
  78                 if (priv->tx_tfm)
  79                         crypto_free_blkcipher(priv->tx_tfm);
  80                 if (priv->rx_tfm)
  81                         crypto_free_blkcipher(priv->rx_tfm);
  82                 kfree(priv);
  83         }
  84         return NULL;
  85 }
  86
  87
  88 static void prism2_wep_deinit(void *priv)
  89 {
  90         struct prism2_wep_data *_priv = priv;
  91         if (_priv) {
  92                 if (_priv->tx_tfm)
  93                         crypto_free_blkcipher(_priv->tx_tfm);
  94                 if (_priv->rx_tfm)
  95                         crypto_free_blkcipher(_priv->rx_tfm);
  96         }
  97         kfree(priv);
  98 }
  99
 100 /* Perform WEP encryption on given skb that has at least 4 bytes of headroom
 101  * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
 102  * so the payload length increases with 8 bytes.
 103  *
 104  * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
 105  */
 106 static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 107 {
 108         struct prism2_wep_data *wep = priv;
 109         u32 klen, len;
 110         u8 key[WEP_KEY_LEN + 3];
 111         u8 *pos;
 112         cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 113         struct blkcipher_desc desc = {.tfm = wep->tx_tfm};
 114         u32 crc;
 115         u8 *icv;
 116         struct scatterlist sg;
 117         if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
 118             skb->len < hdr_len)
 119                 return -1;
 120
 121         len = skb->len - hdr_len;
 122         pos = skb_push(skb, 4);
 123         memmove(pos, pos + 4, hdr_len);
 124         pos += hdr_len;
 125
 126         klen = 3 + wep->key_len;
 127
 128         wep->iv++;
 129
 130         /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
 131          * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
 132          * can be used to speedup attacks, so avoid using them. */
 133         if ((wep->iv & 0xff00) == 0xff00) {
 134                 u8 B = (wep->iv >> 16) & 0xff;
 135                 if (B >= 3 && B < klen)
 136                         wep->iv += 0x0100;
 137         }
 138
 139         /* Prepend 24-bit IV to RC4 key and TX frame */
 140         *pos++ = key[0] = (wep->iv >> 16) & 0xff;
 141         *pos++ = key[1] = (wep->iv >> 8) & 0xff;
 142         *pos++ = key[2] = wep->iv & 0xff;
 143         *pos++ = wep->key_idx << 6;
 144
 145         /* Copy rest of the WEP key (the secret part) */
 146         memcpy(key + 3, wep->key, wep->key_len);
 147
 148         if (!tcb_desc->bHwSec)
 149         {
 150
 151                 /* Append little-endian CRC32 and encrypt it to produce ICV */
 152                 crc = ~crc32_le(~0, pos, len);
 153                 icv = skb_put(skb, 4);
 154                 icv[0] = crc;
 155                 icv[1] = crc >> 8;
 156                 icv[2] = crc >> 16;
 157                 icv[3] = crc >> 24;
 158
 159                 crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
 160                 sg_init_one(&sg, pos, len+4);
 161                 return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
 162         }
 163
 164         return 0;
 165 }
 166
 167
 168 /* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
 169  * the frame: IV (4 bytes), encrypted payload (including SNAP header),
 170  * ICV (4 bytes). len includes both IV and ICV.
 171  *
 172  * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
 173  * failure. If frame is OK, IV and ICV will be removed.
 174  */
 175 static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 176 {
 177         struct prism2_wep_data *wep = priv;
 178         u32  klen, plen;
 179         u8 key[WEP_KEY_LEN + 3];
 180         u8 keyidx, *pos;
 181         cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 182         struct blkcipher_desc desc = {.tfm = wep->rx_tfm};
 183         u32 crc;
 184         u8 icv[4];
 185         struct scatterlist sg;
 186         if (skb->len < hdr_len + 8)
 187                 return -1;
 188
 189         pos = skb->data + hdr_len;
 190         key[0] = *pos++;
 191         key[1] = *pos++;
 192         key[2] = *pos++;
 193         keyidx = *pos++ >> 6;
 194         if (keyidx != wep->key_idx)
 195                 return -1;
 196
 197         klen = 3 + wep->key_len;
 198
 199         /* Copy rest of the WEP key (the secret part) */
 200         memcpy(key + 3, wep->key, wep->key_len);
 201
 202         /* Apply RC4 to data and compute CRC32 over decrypted data */
 203         plen = skb->len - hdr_len - 8;
 204
 205         if (!tcb_desc->bHwSec)
 206         {
 207                 crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
 208                 sg_init_one(&sg, pos, plen+4);
 209                 if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
 210                         return -7;
 211                 crc = ~crc32_le(~0, pos, plen);
 212                 icv[0] = crc;
 213                 icv[1] = crc >> 8;
 214                 icv[2] = crc >> 16;
 215                 icv[3] = crc >> 24;
 216                 if (memcmp(icv, pos + plen, 4) != 0) {
 217                         /* ICV mismatch - drop frame */
 218                         return -2;
 219                 }
 220         }
 221         /* Remove IV and ICV */
 222         memmove(skb->data + 4, skb->data, hdr_len);
 223         skb_pull(skb, 4);
 224         skb_trim(skb, skb->len - 4);
 225
 226         return 0;
 227 }
 228
 229
 230 static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv)
 231 {
 232         struct prism2_wep_data *wep = priv;
 233
 234         if (len < 0 || len > WEP_KEY_LEN)
 235                 return -1;
 236
 237         memcpy(wep->key, key, len);
 238         wep->key_len = len;
 239
 240         return 0;
 241 }
 242
 243
 244 static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv)
 245 {
 246         struct prism2_wep_data *wep = priv;
 247
 248         if (len < wep->key_len)
 249                 return -1;
 250
 251         memcpy(key, wep->key, wep->key_len);
 252
 253         return wep->key_len;
 254 }
 255
 256
 257 static char * prism2_wep_print_stats(char *p, void *priv)
 258 {
 259         struct prism2_wep_data *wep = priv;
 260         p += sprintf(p, "key[%d] alg=WEP len=%d\n",
 261                      wep->key_idx, wep->key_len);
 262         return p;
 263 }
 264
 265
 266 static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
 267         .name                   = "WEP",
 268         .init                   = prism2_wep_init,
 269         .deinit                 = prism2_wep_deinit,
 270         .encrypt_mpdu           = prism2_wep_encrypt,
 271         .decrypt_mpdu           = prism2_wep_decrypt,
 272         .encrypt_msdu           = NULL,
 273         .decrypt_msdu           = NULL,
 274         .set_key                = prism2_wep_set_key,
 275         .get_key                = prism2_wep_get_key,
 276         .print_stats            = prism2_wep_print_stats,
 277         .extra_prefix_len       = 4, /* IV */
 278         .extra_postfix_len      = 4, /* ICV */
 279         .owner                  = THIS_MODULE,
 280 };
 281
 282
 283 int __init ieee80211_crypto_wep_init(void)
 284 {
 285         return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
 286 }
 287
 288
 289 void __exit ieee80211_crypto_wep_exit(void)
 290 {
 291         ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
 292 }
 293
 294 void ieee80211_wep_null(void)
 295 {
 296         return;
 297 }