root/drivers/staging/rtl8192e/rtllib_crypt_wep.c

DEFINITIONS

1. prism2_wep_init
2. prism2_wep_deinit
3. prism2_wep_encrypt
4. prism2_wep_decrypt
5. prism2_wep_set_key
6. prism2_wep_get_key
7. prism2_wep_print_stats
8. rtllib_crypto_wep_init
9. rtllib_crypto_wep_exit

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Host AP crypt: host-based WEP encryption implementation for Host AP driver
   4  *
   5  * Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
   6  */
   7 
   8 #include <crypto/skcipher.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/slab.h>
  12 #include <linux/random.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/string.h>
  15 #include "rtllib.h"
  16 
  17 #include <linux/scatterlist.h>
  18 #include <linux/crc32.h>
  19 
  20 struct prism2_wep_data {
  21         u32 iv;
  22 #define WEP_KEY_LEN 13
  23         u8 key[WEP_KEY_LEN + 1];
  24         u8 key_len;
  25         u8 key_idx;
  26         struct crypto_sync_skcipher *tx_tfm;
  27         struct crypto_sync_skcipher *rx_tfm;
  28 };
  29 
  30 
  31 static void *prism2_wep_init(int keyidx)
  32 {
  33         struct prism2_wep_data *priv;
  34 
  35         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  36         if (priv == NULL)
  37                 goto fail;
  38         priv->key_idx = keyidx;
  39 
  40         priv->tx_tfm = crypto_alloc_sync_skcipher("ecb(arc4)", 0, 0);
  41         if (IS_ERR(priv->tx_tfm)) {
  42                 pr_debug("rtllib_crypt_wep: could not allocate crypto API arc4\n");
  43                 priv->tx_tfm = NULL;
  44                 goto fail;
  45         }
  46         priv->rx_tfm = crypto_alloc_sync_skcipher("ecb(arc4)", 0, 0);
  47         if (IS_ERR(priv->rx_tfm)) {
  48                 pr_debug("rtllib_crypt_wep: could not allocate crypto API arc4\n");
  49                 priv->rx_tfm = NULL;
  50                 goto fail;
  51         }
  52 
  53         /* start WEP IV from a random value */
  54         get_random_bytes(&priv->iv, 4);
  55 
  56         return priv;
  57 
  58 fail:
  59         if (priv) {
  60                 crypto_free_sync_skcipher(priv->tx_tfm);
  61                 crypto_free_sync_skcipher(priv->rx_tfm);
  62                 kfree(priv);
  63         }
  64         return NULL;
  65 }
  66 
  67 
  68 static void prism2_wep_deinit(void *priv)
  69 {
  70         struct prism2_wep_data *_priv = priv;
  71 
  72         if (_priv) {
  73                 crypto_free_sync_skcipher(_priv->tx_tfm);
  74                 crypto_free_sync_skcipher(_priv->rx_tfm);
  75         }
  76         kfree(priv);
  77 }
  78 
  79 /* Perform WEP encryption on given skb that has at least 4 bytes of headroom
  80  * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
  81  * so the payload length increases with 8 bytes.
  82  *
  83  * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
  84  */
  85 static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
  86 {
  87         struct prism2_wep_data *wep = priv;
  88         u32 klen, len;
  89         u8 key[WEP_KEY_LEN + 3];
  90         u8 *pos;
  91         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
  92                                     MAX_DEV_ADDR_SIZE);
  93         u32 crc;
  94         u8 *icv;
  95         struct scatterlist sg;
  96         int err;
  97 
  98         if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
  99             skb->len < hdr_len){
 100                 pr_err("Error!!! headroom=%d tailroom=%d skblen=%d hdr_len=%d\n",
 101                        skb_headroom(skb), skb_tailroom(skb), skb->len, hdr_len);
 102                 return -1;
 103         }
 104         len = skb->len - hdr_len;
 105         pos = skb_push(skb, 4);
 106         memmove(pos, pos + 4, hdr_len);
 107         pos += hdr_len;
 108 
 109         klen = 3 + wep->key_len;
 110 
 111         wep->iv++;
 112 
 113         /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
 114          * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
 115          * can be used to speedup attacks, so avoid using them.
 116          */
 117         if ((wep->iv & 0xff00) == 0xff00) {
 118                 u8 B = (wep->iv >> 16) & 0xff;
 119 
 120                 if (B >= 3 && B < klen)
 121                         wep->iv += 0x0100;
 122         }
 123 
 124         /* Prepend 24-bit IV to RC4 key and TX frame */
 125         *pos++ = key[0] = (wep->iv >> 16) & 0xff;
 126         *pos++ = key[1] = (wep->iv >> 8) & 0xff;
 127         *pos++ = key[2] = wep->iv & 0xff;
 128         *pos++ = wep->key_idx << 6;
 129 
 130         /* Copy rest of the WEP key (the secret part) */
 131         memcpy(key + 3, wep->key, wep->key_len);
 132 
 133         if (!tcb_desc->bHwSec) {
 134                 SYNC_SKCIPHER_REQUEST_ON_STACK(req, wep->tx_tfm);
 135 
 136                 /* Append little-endian CRC32 and encrypt it to produce ICV */
 137                 crc = ~crc32_le(~0, pos, len);
 138                 icv = skb_put(skb, 4);
 139                 icv[0] = crc;
 140                 icv[1] = crc >> 8;
 141                 icv[2] = crc >> 16;
 142                 icv[3] = crc >> 24;
 143 
 144                 sg_init_one(&sg, pos, len+4);
 145                 crypto_sync_skcipher_setkey(wep->tx_tfm, key, klen);
 146                 skcipher_request_set_sync_tfm(req, wep->tx_tfm);
 147                 skcipher_request_set_callback(req, 0, NULL, NULL);
 148                 skcipher_request_set_crypt(req, &sg, &sg, len + 4, NULL);
 149                 err = crypto_skcipher_encrypt(req);
 150                 skcipher_request_zero(req);
 151                 return err;
 152         }
 153 
 154         return 0;
 155 }
 156 
 157 
 158 /* Perform WEP decryption on given struct buffer. Buffer includes whole WEP
 159  * part of the frame: IV (4 bytes), encrypted payload (including SNAP header),
 160  * ICV (4 bytes). len includes both IV and ICV.
 161  *
 162  * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
 163  * failure. If frame is OK, IV and ICV will be removed.
 164  */
 165 static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 166 {
 167         struct prism2_wep_data *wep = priv;
 168         u32  klen, plen;
 169         u8 key[WEP_KEY_LEN + 3];
 170         u8 keyidx, *pos;
 171         struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 172                                     MAX_DEV_ADDR_SIZE);
 173         u32 crc;
 174         u8 icv[4];
 175         struct scatterlist sg;
 176         int err;
 177 
 178         if (skb->len < hdr_len + 8)
 179                 return -1;
 180 
 181         pos = skb->data + hdr_len;
 182         key[0] = *pos++;
 183         key[1] = *pos++;
 184         key[2] = *pos++;
 185         keyidx = *pos++ >> 6;
 186         if (keyidx != wep->key_idx)
 187                 return -1;
 188 
 189         klen = 3 + wep->key_len;
 190 
 191         /* Copy rest of the WEP key (the secret part) */
 192         memcpy(key + 3, wep->key, wep->key_len);
 193 
 194         /* Apply RC4 to data and compute CRC32 over decrypted data */
 195         plen = skb->len - hdr_len - 8;
 196 
 197         if (!tcb_desc->bHwSec) {
 198                 SYNC_SKCIPHER_REQUEST_ON_STACK(req, wep->rx_tfm);
 199 
 200                 sg_init_one(&sg, pos, plen+4);
 201                 crypto_sync_skcipher_setkey(wep->rx_tfm, key, klen);
 202                 skcipher_request_set_sync_tfm(req, wep->rx_tfm);
 203                 skcipher_request_set_callback(req, 0, NULL, NULL);
 204                 skcipher_request_set_crypt(req, &sg, &sg, plen + 4, NULL);
 205                 err = crypto_skcipher_decrypt(req);
 206                 skcipher_request_zero(req);
 207                 if (err)
 208                         return -7;
 209                 crc = ~crc32_le(~0, pos, plen);
 210                 icv[0] = crc;
 211                 icv[1] = crc >> 8;
 212                 icv[2] = crc >> 16;
 213                 icv[3] = crc >> 24;
 214                 if (memcmp(icv, pos + plen, 4) != 0) {
 215                         /* ICV mismatch - drop frame */
 216                         return -2;
 217                 }
 218         }
 219         /* Remove IV and ICV */
 220         memmove(skb->data + 4, skb->data, hdr_len);
 221         skb_pull(skb, 4);
 222         skb_trim(skb, skb->len - 4);
 223 
 224         return 0;
 225 }
 226 
 227 
 228 static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv)
 229 {
 230         struct prism2_wep_data *wep = priv;
 231 
 232         if (len < 0 || len > WEP_KEY_LEN)
 233                 return -1;
 234 
 235         memcpy(wep->key, key, len);
 236         wep->key_len = len;
 237 
 238         return 0;
 239 }
 240 
 241 
 242 static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv)
 243 {
 244         struct prism2_wep_data *wep = priv;
 245 
 246         if (len < wep->key_len)
 247                 return -1;
 248 
 249         memcpy(key, wep->key, wep->key_len);
 250 
 251         return wep->key_len;
 252 }
 253 
 254 
 255 static void prism2_wep_print_stats(struct seq_file *m, void *priv)
 256 {
 257         struct prism2_wep_data *wep = priv;
 258 
 259         seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
 260 }
 261 
 262 static struct lib80211_crypto_ops rtllib_crypt_wep = {
 263         .name                   = "R-WEP",
 264         .init                   = prism2_wep_init,
 265         .deinit                 = prism2_wep_deinit,
 266         .encrypt_mpdu           = prism2_wep_encrypt,
 267         .decrypt_mpdu           = prism2_wep_decrypt,
 268         .encrypt_msdu           = NULL,
 269         .decrypt_msdu           = NULL,
 270         .set_key                = prism2_wep_set_key,
 271         .get_key                = prism2_wep_get_key,
 272         .print_stats            = prism2_wep_print_stats,
 273         .extra_mpdu_prefix_len  = 4,    /* IV */
 274         .extra_mpdu_postfix_len = 4,    /* ICV */
 275         .owner                  = THIS_MODULE,
 276 };
 277 
 278 
 279 static int __init rtllib_crypto_wep_init(void)
 280 {
 281         return lib80211_register_crypto_ops(&rtllib_crypt_wep);
 282 }
 283 
 284 
 285 static void __exit rtllib_crypto_wep_exit(void)
 286 {
 287         lib80211_unregister_crypto_ops(&rtllib_crypt_wep);
 288 }
 289 
 290 module_init(rtllib_crypto_wep_init);
 291 module_exit(rtllib_crypto_wep_exit);
 292 
 293 MODULE_LICENSE("GPL");