drivers/staging/wlan-ng/p80211wep.c

   1 // SPDX-License-Identifier: (GPL-2.0 OR MPL-1.1)
   2 /* src/p80211/p80211wep.c
   3  *
   4  * WEP encode/decode for P80211.
   5  *
   6  * Copyright (C) 2002 AbsoluteValue Systems, Inc.  All Rights Reserved.
   7  * --------------------------------------------------------------------
   8  *
   9  * linux-wlan
  10  *
  11  *   The contents of this file are subject to the Mozilla Public
  12  *   License Version 1.1 (the "License"); you may not use this file
  13  *   except in compliance with the License. You may obtain a copy of
  14  *   the License at http://www.mozilla.org/MPL/
  15  *
  16  *   Software distributed under the License is distributed on an "AS
  17  *   IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
  18  *   implied. See the License for the specific language governing
  19  *   rights and limitations under the License.
  20  *
  21  *   Alternatively, the contents of this file may be used under the
  22  *   terms of the GNU Public License version 2 (the "GPL"), in which
  23  *   case the provisions of the GPL are applicable instead of the
  24  *   above.  If you wish to allow the use of your version of this file
  25  *   only under the terms of the GPL and not to allow others to use
  26  *   your version of this file under the MPL, indicate your decision
  27  *   by deleting the provisions above and replace them with the notice
  28  *   and other provisions required by the GPL.  If you do not delete
  29  *   the provisions above, a recipient may use your version of this
  30  *   file under either the MPL or the GPL.
  31  *
  32  * --------------------------------------------------------------------
  33  *
  34  * Inquiries regarding the linux-wlan Open Source project can be
  35  * made directly to:
  36  *
  37  * AbsoluteValue Systems Inc.
  38  * info@linux-wlan.com
  39  * http://www.linux-wlan.com
  40  *
  41  * --------------------------------------------------------------------
  42  *
  43  * Portions of the development of this software were funded by
  44  * Intersil Corporation as part of PRISM(R) chipset product development.
  45  *
  46  * --------------------------------------------------------------------
  47  */
  48
  49 /*================================================================*/
  50 /* System Includes */
  51
  52 #include <linux/crc32.h>
  53 #include <linux/netdevice.h>
  54 #include <linux/wireless.h>
  55 #include <linux/random.h>
  56 #include <linux/kernel.h>
  57 #include "p80211hdr.h"
  58 #include "p80211types.h"
  59 #include "p80211msg.h"
  60 #include "p80211conv.h"
  61 #include "p80211netdev.h"
  62
  63 #define WEP_KEY(x)       (((x) & 0xC0) >> 6)
  64
  65 /* keylen in bytes! */
  66
  67 int wep_change_key(struct wlandevice *wlandev, int keynum, u8 *key, int keylen)
  68 {
  69         if (keylen < 0)
  70                 return -1;
  71         if (keylen >= MAX_KEYLEN)
  72                 return -1;
  73         if (!key)
  74                 return -1;
  75         if (keynum < 0)
  76                 return -1;
  77         if (keynum >= NUM_WEPKEYS)
  78                 return -1;
  79
  80         wlandev->wep_keylens[keynum] = keylen;
  81         memcpy(wlandev->wep_keys[keynum], key, keylen);
  82
  83         return 0;
  84 }
  85
  86 /*
  87  * 4-byte IV at start of buffer, 4-byte ICV at end of buffer.
  88  * if successful, buf start is payload begin, length -= 8;
  89  */
  90 int wep_decrypt(struct wlandevice *wlandev, u8 *buf, u32 len, int key_override,
  91                 u8 *iv, u8 *icv)
  92 {
  93         u32 i, j, k, crc, keylen;
  94         u8 s[256], key[64], c_crc[4];
  95         u8 keyidx;
  96
  97         /* Needs to be at least 8 bytes of payload */
  98         if (len <= 0)
  99                 return -1;
 100
 101         /* initialize the first bytes of the key from the IV */
 102         key[0] = iv[0];
 103         key[1] = iv[1];
 104         key[2] = iv[2];
 105         keyidx = WEP_KEY(iv[3]);
 106
 107         if (key_override >= 0)
 108                 keyidx = key_override;
 109
 110         if (keyidx >= NUM_WEPKEYS)
 111                 return -2;
 112
 113         keylen = wlandev->wep_keylens[keyidx];
 114
 115         if (keylen == 0)
 116                 return -3;
 117
 118         /* copy the rest of the key over from the designated key */
 119         memcpy(key + 3, wlandev->wep_keys[keyidx], keylen);
 120
 121         keylen += 3;            /* add in IV bytes */
 122
 123         /* set up the RC4 state */
 124         for (i = 0; i < 256; i++)
 125                 s[i] = i;
 126         j = 0;
 127         for (i = 0; i < 256; i++) {
 128                 j = (j + s[i] + key[i % keylen]) & 0xff;
 129                 swap(i, j);
 130         }
 131
 132         /* Apply the RC4 to the data, update the CRC32 */
 133         i = 0;
 134         j = 0;
 135         for (k = 0; k < len; k++) {
 136                 i = (i + 1) & 0xff;
 137                 j = (j + s[i]) & 0xff;
 138                 swap(i, j);
 139                 buf[k] ^= s[(s[i] + s[j]) & 0xff];
 140         }
 141         crc = ~crc32_le(~0, buf, len);
 142
 143         /* now let's check the crc */
 144         c_crc[0] = crc;
 145         c_crc[1] = crc >> 8;
 146         c_crc[2] = crc >> 16;
 147         c_crc[3] = crc >> 24;
 148
 149         for (k = 0; k < 4; k++) {
 150                 i = (i + 1) & 0xff;
 151                 j = (j + s[i]) & 0xff;
 152                 swap(i, j);
 153                 if ((c_crc[k] ^ s[(s[i] + s[j]) & 0xff]) != icv[k])
 154                         return -(4 | (k << 4)); /* ICV mismatch */
 155         }
 156
 157         return 0;
 158 }
 159
 160 /* encrypts in-place. */
 161 int wep_encrypt(struct wlandevice *wlandev, u8 *buf,
 162                 u8 *dst, u32 len, int keynum, u8 *iv, u8 *icv)
 163 {
 164         u32 i, j, k, crc, keylen;
 165         u8 s[256], key[64];
 166
 167         /* no point in WEPping an empty frame */
 168         if (len <= 0)
 169                 return -1;
 170
 171         /* we need to have a real key.. */
 172         if (keynum >= NUM_WEPKEYS)
 173                 return -2;
 174         keylen = wlandev->wep_keylens[keynum];
 175         if (keylen <= 0)
 176                 return -3;
 177
 178         /* use a random IV.  And skip known weak ones. */
 179         get_random_bytes(iv, 3);
 180         while ((iv[1] == 0xff) && (iv[0] >= 3) && (iv[0] < keylen))
 181                 get_random_bytes(iv, 3);
 182
 183         iv[3] = (keynum & 0x03) << 6;
 184
 185         key[0] = iv[0];
 186         key[1] = iv[1];
 187         key[2] = iv[2];
 188
 189         /* copy the rest of the key over from the designated key */
 190         memcpy(key + 3, wlandev->wep_keys[keynum], keylen);
 191
 192         keylen += 3;            /* add in IV bytes */
 193
 194         /* set up the RC4 state */
 195         for (i = 0; i < 256; i++)
 196                 s[i] = i;
 197         j = 0;
 198         for (i = 0; i < 256; i++) {
 199                 j = (j + s[i] + key[i % keylen]) & 0xff;
 200                 swap(i, j);
 201         }
 202
 203         /* Update CRC32 then apply RC4 to the data */
 204         i = 0;
 205         j = 0;
 206         for (k = 0; k < len; k++) {
 207                 i = (i + 1) & 0xff;
 208                 j = (j + s[i]) & 0xff;
 209                 swap(i, j);
 210                 dst[k] = buf[k] ^ s[(s[i] + s[j]) & 0xff];
 211         }
 212         crc = ~crc32_le(~0, buf, len);
 213
 214         /* now let's encrypt the crc */
 215         icv[0] = crc;
 216         icv[1] = crc >> 8;
 217         icv[2] = crc >> 16;
 218         icv[3] = crc >> 24;
 219
 220         for (k = 0; k < 4; k++) {
 221                 i = (i + 1) & 0xff;
 222                 j = (j + s[i]) & 0xff;
 223                 swap(i, j);
 224                 icv[k] ^= s[(s[i] + s[j]) & 0xff];
 225         }
 226
 227         return 0;
 228 }