drivers/net/wireless/rt2x00/rt2x00crypto.c

   1 /*
   2         Copyright (C) 2004 - 2008 rt2x00 SourceForge Project
   3         <http://rt2x00.serialmonkey.com>
   4
   5         This program is free software; you can redistribute it and/or modify
   6         it under the terms of the GNU General Public License as published by
   7         the Free Software Foundation; either version 2 of the License, or
   8         (at your option) any later version.
   9
  10         This program is distributed in the hope that it will be useful,
  11         but WITHOUT ANY WARRANTY; without even the implied warranty of
  12         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13         GNU General Public License for more details.
  14
  15         You should have received a copy of the GNU General Public License
  16         along with this program; if not, write to the
  17         Free Software Foundation, Inc.,
  18         59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 /*
  22         Module: rt2x00lib
  23         Abstract: rt2x00 crypto specific routines.
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28
  29 #include "rt2x00.h"
  30 #include "rt2x00lib.h"
  31
  32 enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
  33 {
  34         switch (key->alg) {
  35         case ALG_WEP:
  36                 if (key->keylen == LEN_WEP40)
  37                         return CIPHER_WEP64;
  38                 else
  39                         return CIPHER_WEP128;
  40         case ALG_TKIP:
  41                 return CIPHER_TKIP;
  42         case ALG_CCMP:
  43                 return CIPHER_AES;
  44         default:
  45                 return CIPHER_NONE;
  46         }
  47 }
  48
  49 void rt2x00crypto_create_tx_descriptor(struct queue_entry *entry,
  50                                        struct txentry_desc *txdesc)
  51 {
  52         struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
  53         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
  54         struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
  55
  56         if (!test_bit(CONFIG_SUPPORT_HW_CRYPTO, &rt2x00dev->flags) ||
  57             !hw_key || entry->skb->do_not_encrypt)
  58                 return;
  59
  60         __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);
  61
  62         txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);
  63
  64         if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
  65                 __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);
  66
  67         txdesc->key_idx = hw_key->hw_key_idx;
  68         txdesc->iv_offset = ieee80211_get_hdrlen_from_skb(entry->skb);
  69
  70         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  71                 __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);
  72
  73         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
  74                 __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
  75 }
  76
  77 unsigned int rt2x00crypto_tx_overhead(struct rt2x00_dev *rt2x00dev,
  78                                       struct sk_buff *skb)
  79 {
  80         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
  81         struct ieee80211_key_conf *key = tx_info->control.hw_key;
  82         unsigned int overhead = 0;
  83
  84         if (!test_bit(CONFIG_SUPPORT_HW_CRYPTO, &rt2x00dev->flags) ||
  85             !key || skb->do_not_encrypt)
  86                 return overhead;
  87
  88         /*
  89          * Extend frame length to include IV/EIV/ICV/MMIC,
  90          * note that these lengths should only be added when
  91          * mac80211 does not generate it.
  92          */
  93         overhead += key->icv_len;
  94
  95         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  96                 overhead += key->iv_len;
  97
  98         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
  99                 if (key->alg == ALG_TKIP)
 100                         overhead += 8;
 101         }
 102
 103         return overhead;
 104 }
 105
 106 void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, unsigned int iv_len)
 107 {
 108         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 109         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
 110
 111         if (unlikely(!iv_len))
 112                 return;
 113
 114         /* Copy IV/EIV data */
 115         memcpy(skbdesc->iv, skb->data + header_length, iv_len);
 116 }
 117
 118 void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, unsigned int iv_len)
 119 {
 120         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 121         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
 122
 123         if (unlikely(!iv_len))
 124                 return;
 125
 126         /* Copy IV/EIV data */
 127         memcpy(skbdesc->iv, skb->data + header_length, iv_len);
 128
 129         /* Move ieee80211 header */
 130         memmove(skb->data + iv_len, skb->data, header_length);
 131
 132         /* Pull buffer to correct size */
 133         skb_pull(skb, iv_len);
 134
 135         /* IV/EIV data has officially be stripped */
 136         skbdesc->flags |= FRAME_DESC_IV_STRIPPED;
 137 }
 138
 139 void rt2x00crypto_tx_insert_iv(struct sk_buff *skb)
 140 {
 141         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 142         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
 143         const unsigned int iv_len =
 144             ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);
 145
 146         if (!(skbdesc->flags & FRAME_DESC_IV_STRIPPED))
 147                 return;
 148
 149         skb_push(skb, iv_len);
 150
 151         /* Move ieee80211 header */
 152         memmove(skb->data, skb->data + iv_len, header_length);
 153
 154         /* Copy IV/EIV data */
 155         memcpy(skb->data + header_length, skbdesc->iv, iv_len);
 156
 157         /* IV/EIV data has returned into the frame */
 158         skbdesc->flags &= ~FRAME_DESC_IV_STRIPPED;
 159 }
 160
 161 void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, unsigned int align,
 162                                unsigned int header_length,
 163                                struct rxdone_entry_desc *rxdesc)
 164 {
 165         unsigned int payload_len = rxdesc->size - header_length;
 166         unsigned int iv_len;
 167         unsigned int icv_len;
 168         unsigned int transfer = 0;
 169
 170         /*
 171          * WEP64/WEP128: Provides IV & ICV
 172          * TKIP: Provides IV/EIV & ICV
 173          * AES: Provies IV/EIV & ICV
 174          */
 175         switch (rxdesc->cipher) {
 176         case CIPHER_WEP64:
 177         case CIPHER_WEP128:
 178                 iv_len = 4;
 179                 icv_len = 4;
 180                 break;
 181         case CIPHER_TKIP:
 182                 iv_len = 8;
 183                 icv_len = 4;
 184                 break;
 185         case CIPHER_AES:
 186                 iv_len = 8;
 187                 icv_len = 8;
 188                 break;
 189         default:
 190                 /* Unsupport type */
 191                 return;
 192         }
 193
 194         /*
 195          * Make room for new data, note that we increase both
 196          * headsize and tailsize when required. The tailsize is
 197          * only needed when ICV data needs to be inserted and
 198          * the padding is smaller than the ICV data.
 199          * When alignment requirements is greater than the
 200          * ICV data we must trim the skb to the correct size
 201          * because we need to remove the extra bytes.
 202          */
 203         skb_push(skb, iv_len + align);
 204         if (align < icv_len)
 205                 skb_put(skb, icv_len - align);
 206         else if (align > icv_len)
 207                 skb_trim(skb, rxdesc->size + iv_len + icv_len);
 208
 209         /* Move ieee80211 header */
 210         memmove(skb->data + transfer,
 211                 skb->data + transfer + iv_len + align,
 212                 header_length);
 213         transfer += header_length;
 214
 215         /* Copy IV/EIV data */
 216         memcpy(skb->data + transfer, rxdesc->iv, iv_len);
 217         transfer += iv_len;
 218
 219         /* Move payload */
 220         if (align) {
 221                 memmove(skb->data + transfer,
 222                         skb->data + transfer + align,
 223                         payload_len);
 224         }
 225
 226         /*
 227          * NOTE: Always count the payload as transfered,
 228          * even when alignment was set to zero. This is required
 229          * for determining the correct offset for the ICV data.
 230          */
 231         transfer += payload_len;
 232
 233         /*
 234          * Copy ICV data
 235          * AES appends 8 bytes, we can't fill the upper
 236          * 4 bytes, but mac80211 doesn't care about what
 237          * we provide here anyway and strips it immediately.
 238          */
 239         memcpy(skb->data + transfer, &rxdesc->icv, 4);
 240         transfer += icv_len;
 241
 242         /* IV/EIV/ICV has been inserted into frame */
 243         rxdesc->size = transfer;
 244         rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
 245 }