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 ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
  53         struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
  54
  55         __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);
  56
  57         txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);
  58
  59         if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
  60                 __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);
  61
  62         txdesc->key_idx = hw_key->hw_key_idx;
  63         txdesc->iv_offset = ieee80211_get_hdrlen_from_skb(entry->skb);
  64
  65         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  66                 __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);
  67
  68         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
  69                 __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
  70 }
  71
  72 unsigned int rt2x00crypto_tx_overhead(struct ieee80211_tx_info *tx_info)
  73 {
  74         struct ieee80211_key_conf *key = tx_info->control.hw_key;
  75         unsigned int overhead = 0;
  76
  77         /*
  78          * Extend frame length to include IV/EIV/ICV/MMIC,
  79          * note that these lengths should only be added when
  80          * mac80211 does not generate it.
  81          */
  82         overhead += key->icv_len;
  83
  84         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  85                 overhead += key->iv_len;
  86
  87         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
  88                 if (key->alg == ALG_TKIP)
  89                         overhead += 8;
  90         }
  91
  92         return overhead;
  93 }
  94
  95 void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, unsigned int iv_len)
  96 {
  97         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
  98         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
  99
 100         if (unlikely(!iv_len))
 101                 return;
 102
 103         /* Copy IV/EIV data */
 104         memcpy(skbdesc->iv, skb->data + header_length, iv_len);
 105 }
 106
 107 void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, unsigned int iv_len)
 108 {
 109         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 110         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
 111
 112         if (unlikely(!iv_len))
 113                 return;
 114
 115         /* Copy IV/EIV data */
 116         memcpy(skbdesc->iv, skb->data + header_length, iv_len);
 117
 118         /* Move ieee80211 header */
 119         memmove(skb->data + iv_len, skb->data, header_length);
 120
 121         /* Pull buffer to correct size */
 122         skb_pull(skb, iv_len);
 123
 124         /* IV/EIV data has officially be stripped */
 125         skbdesc->flags |= FRAME_DESC_IV_STRIPPED;
 126 }
 127
 128 void rt2x00crypto_tx_insert_iv(struct sk_buff *skb)
 129 {
 130         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 131         unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
 132         const unsigned int iv_len =
 133             ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);
 134
 135         if (!(skbdesc->flags & FRAME_DESC_IV_STRIPPED))
 136                 return;
 137
 138         skb_push(skb, iv_len);
 139
 140         /* Move ieee80211 header */
 141         memmove(skb->data, skb->data + iv_len, header_length);
 142
 143         /* Copy IV/EIV data */
 144         memcpy(skb->data + header_length, skbdesc->iv, iv_len);
 145
 146         /* IV/EIV data has returned into the frame */
 147         skbdesc->flags &= ~FRAME_DESC_IV_STRIPPED;
 148 }
 149
 150 void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, unsigned int align,
 151                                unsigned int header_length,
 152                                struct rxdone_entry_desc *rxdesc)
 153 {
 154         unsigned int payload_len = rxdesc->size - header_length;
 155         unsigned int iv_len;
 156         unsigned int icv_len;
 157         unsigned int transfer = 0;
 158
 159         /*
 160          * WEP64/WEP128: Provides IV & ICV
 161          * TKIP: Provides IV/EIV & ICV
 162          * AES: Provies IV/EIV & ICV
 163          */
 164         switch (rxdesc->cipher) {
 165         case CIPHER_WEP64:
 166         case CIPHER_WEP128:
 167                 iv_len = 4;
 168                 icv_len = 4;
 169                 break;
 170         case CIPHER_TKIP:
 171                 iv_len = 8;
 172                 icv_len = 4;
 173                 break;
 174         case CIPHER_AES:
 175                 iv_len = 8;
 176                 icv_len = 8;
 177                 break;
 178         default:
 179                 /* Unsupport type */
 180                 return;
 181         }
 182
 183         /*
 184          * Make room for new data, note that we increase both
 185          * headsize and tailsize when required. The tailsize is
 186          * only needed when ICV data needs to be inserted and
 187          * the padding is smaller than the ICV data.
 188          * When alignment requirements is greater than the
 189          * ICV data we must trim the skb to the correct size
 190          * because we need to remove the extra bytes.
 191          */
 192         skb_push(skb, iv_len + align);
 193         if (align < icv_len)
 194                 skb_put(skb, icv_len - align);
 195         else if (align > icv_len)
 196                 skb_trim(skb, rxdesc->size + iv_len + icv_len);
 197
 198         /* Move ieee80211 header */
 199         memmove(skb->data + transfer,
 200                 skb->data + transfer + iv_len + align,
 201                 header_length);
 202         transfer += header_length;
 203
 204         /* Copy IV/EIV data */
 205         memcpy(skb->data + transfer, rxdesc->iv, iv_len);
 206         transfer += iv_len;
 207
 208         /* Move payload */
 209         if (align) {
 210                 memmove(skb->data + transfer,
 211                         skb->data + transfer + align,
 212                         payload_len);
 213         }
 214
 215         /*
 216          * NOTE: Always count the payload as transfered,
 217          * even when alignment was set to zero. This is required
 218          * for determining the correct offset for the ICV data.
 219          */
 220         transfer += payload_len;
 221
 222         /*
 223          * Copy ICV data
 224          * AES appends 8 bytes, we can't fill the upper
 225          * 4 bytes, but mac80211 doesn't care about what
 226          * we provide here anyway and strips it immediately.
 227          */
 228         memcpy(skb->data + transfer, &rxdesc->icv, 4);
 229         transfer += icv_len;
 230
 231         /* IV/EIV/ICV has been inserted into frame */
 232         rxdesc->size = transfer;
 233         rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
 234 }