drivers/staging/rtl8192u/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 #include <linux/crypto.h>
  24     #include <linux/scatterlist.h>
  25 #include <linux/crc32.h>
  26
  27 MODULE_AUTHOR("Jouni Malinen");
  28 MODULE_DESCRIPTION("Host AP crypt: WEP");
  29 MODULE_LICENSE("GPL");
  30
  31 struct prism2_wep_data {
  32         u32 iv;
  33 #define WEP_KEY_LEN 13
  34         u8 key[WEP_KEY_LEN + 1];
  35         u8 key_len;
  36         u8 key_idx;
  37         struct crypto_blkcipher *tx_tfm;
  38         struct crypto_blkcipher *rx_tfm;
  39 };
  40
  41
  42 static void * prism2_wep_init(int keyidx)
  43 {
  44         struct prism2_wep_data *priv;
  45
  46         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  47         if (priv == NULL)
  48                 goto fail;
  49         priv->key_idx = keyidx;
  50
  51         priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
  52         if (IS_ERR(priv->tx_tfm)) {
  53                 printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
  54                        "crypto API arc4\n");
  55                 priv->tx_tfm = NULL;
  56                 goto fail;
  57         }
  58         priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
  59         if (IS_ERR(priv->rx_tfm)) {
  60                 printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
  61                        "crypto API arc4\n");
  62                 priv->rx_tfm = NULL;
  63                 goto fail;
  64         }
  65
  66         /* start WEP IV from a random value */
  67         get_random_bytes(&priv->iv, 4);
  68
  69         return priv;
  70
  71 fail:
  72         if (priv) {
  73                 if (priv->tx_tfm)
  74                         crypto_free_blkcipher(priv->tx_tfm);
  75                 if (priv->rx_tfm)
  76                         crypto_free_blkcipher(priv->rx_tfm);
  77                 kfree(priv);
  78         }
  79
  80         return NULL;
  81 }
  82
  83
  84 static void prism2_wep_deinit(void *priv)
  85 {
  86         struct prism2_wep_data *_priv = priv;
  87
  88         if (_priv) {
  89                 if (_priv->tx_tfm)
  90                         crypto_free_blkcipher(_priv->tx_tfm);
  91                 if (_priv->rx_tfm)
  92                         crypto_free_blkcipher(_priv->rx_tfm);
  93         }
  94         kfree(priv);
  95 }
  96
  97 /* Perform WEP encryption on given skb that has at least 4 bytes of headroom
  98  * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
  99  * so the payload length increases with 8 bytes.
 100  *
 101  * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
 102  */
 103 static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 104 {
 105         struct prism2_wep_data *wep = priv;
 106         u32 klen, len;
 107         u8 key[WEP_KEY_LEN + 3];
 108         u8 *pos;
 109         cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 110         struct blkcipher_desc desc = {.tfm = wep->tx_tfm};
 111         u32 crc;
 112         u8 *icv;
 113         struct scatterlist sg;
 114         if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
 115             skb->len < hdr_len)
 116                 return -1;
 117
 118         len = skb->len - hdr_len;
 119         pos = skb_push(skb, 4);
 120         memmove(pos, pos + 4, hdr_len);
 121         pos += hdr_len;
 122
 123         klen = 3 + wep->key_len;
 124
 125         wep->iv++;
 126
 127         /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
 128          * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
 129          * can be used to speedup attacks, so avoid using them. */
 130         if ((wep->iv & 0xff00) == 0xff00) {
 131                 u8 B = (wep->iv >> 16) & 0xff;
 132                 if (B >= 3 && B < klen)
 133                         wep->iv += 0x0100;
 134         }
 135
 136         /* Prepend 24-bit IV to RC4 key and TX frame */
 137         *pos++ = key[0] = (wep->iv >> 16) & 0xff;
 138         *pos++ = key[1] = (wep->iv >> 8) & 0xff;
 139         *pos++ = key[2] = wep->iv & 0xff;
 140         *pos++ = wep->key_idx << 6;
 141
 142         /* Copy rest of the WEP key (the secret part) */
 143         memcpy(key + 3, wep->key, wep->key_len);
 144
 145         if (!tcb_desc->bHwSec)
 146         {
 147
 148                 /* Append little-endian CRC32 and encrypt it to produce ICV */
 149                 crc = ~crc32_le(~0, pos, len);
 150                 icv = skb_put(skb, 4);
 151                 icv[0] = crc;
 152                 icv[1] = crc >> 8;
 153                 icv[2] = crc >> 16;
 154                 icv[3] = crc >> 24;
 155
 156                 crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
 157                 sg_init_one(&sg, pos, len+4);
 158
 159                 return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
 160         }
 161
 162         return 0;
 163 }
 164
 165
 166 /* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
 167  * the frame: IV (4 bytes), encrypted payload (including SNAP header),
 168  * ICV (4 bytes). len includes both IV and ICV.
 169  *
 170  * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
 171  * failure. If frame is OK, IV and ICV will be removed.
 172  */
 173 static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 174 {
 175         struct prism2_wep_data *wep = priv;
 176         u32  klen, plen;
 177         u8 key[WEP_KEY_LEN + 3];
 178         u8 keyidx, *pos;
 179         cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 180         struct blkcipher_desc desc = {.tfm = wep->rx_tfm};
 181         u32 crc;
 182         u8 icv[4];
 183         struct scatterlist sg;
 184         if (skb->len < hdr_len + 8)
 185                 return -1;
 186
 187         pos = skb->data + hdr_len;
 188         key[0] = *pos++;
 189         key[1] = *pos++;
 190         key[2] = *pos++;
 191         keyidx = *pos++ >> 6;
 192         if (keyidx != wep->key_idx)
 193                 return -1;
 194
 195         klen = 3 + wep->key_len;
 196
 197         /* Copy rest of the WEP key (the secret part) */
 198         memcpy(key + 3, wep->key, wep->key_len);
 199
 200         /* Apply RC4 to data and compute CRC32 over decrypted data */
 201         plen = skb->len - hdr_len - 8;
 202
 203         if (!tcb_desc->bHwSec)
 204         {
 205                 crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
 206                 sg_init_one(&sg, pos, plen+4);
 207
 208                 if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
 209                         return -7;
 210
 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 int __init ieee80211_crypto_wep_init(void)
 283 {
 284         return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
 285 }
 286
 287 void __exit ieee80211_crypto_wep_exit(void)
 288 {
 289         ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
 290 }
 291
 292 void ieee80211_wep_null(void)
 293 {
 294 //      printk("============>%s()\n", __FUNCTION__);
 295         return;
 296 }