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/version.h> 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/slab.h> 16 #include <linux/random.h> 17 #include <linux/skbuff.h> 18 #include <asm/string.h> 19 #include "rtllib.h" 20 21 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,20)) 22 #endif 23 24 25 #if defined(BUILT_IN_CRYPTO) || (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)) 26 #include "rtl_crypto.h" 27 #else 28 #include <linux/crypto.h> 29 #endif 30 31 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20) 32 #include <asm/scatterlist.h> 33 #else 34 #include <linux/scatterlist.h> 35 #endif 36 #include <linux/crc32.h> 37 /* 38 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)) 39 #include "rtl_crypto.h" 40 #else 41 #include <linux/crypto.h> 42 #endif 43 44 #include <asm/scatterlist.h> 45 #include <linux/crc32.h> 46 */ 47 struct prism2_wep_data { 48 u32 iv; 49 #define WEP_KEY_LEN 13 50 u8 key[WEP_KEY_LEN + 1]; 51 u8 key_len; 52 u8 key_idx; 53 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 54 struct crypto_tfm *tfm; 55 #else 56 struct crypto_blkcipher *tx_tfm; 57 struct crypto_blkcipher *rx_tfm; 58 #endif 59 }; 60 61 62 static void * prism2_wep_init(int keyidx) 63 { 64 struct prism2_wep_data *priv; 65 66 priv = kmalloc(sizeof(*priv), GFP_ATOMIC); 67 if (priv == NULL) 68 goto fail; 69 memset(priv, 0, sizeof(*priv)); 70 priv->key_idx = keyidx; 71 72 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 73 priv->tfm = crypto_alloc_tfm("arc4", 0); 74 if (priv->tfm == NULL) { 75 printk(KERN_DEBUG "rtllib_crypt_wep: could not allocate " 76 "crypto API arc4\n"); 77 goto fail; 78 } 79 #else 80 priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); 81 if (IS_ERR(priv->tx_tfm)) { 82 printk(KERN_DEBUG "rtllib_crypt_wep: could not allocate " 83 "crypto API arc4\n"); 84 priv->tx_tfm = NULL; 85 goto fail; 86 } 87 priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); 88 if (IS_ERR(priv->rx_tfm)) { 89 printk(KERN_DEBUG "rtllib_crypt_wep: could not allocate " 90 "crypto API arc4\n"); 91 priv->rx_tfm = NULL; 92 goto fail; 93 } 94 #endif 95 96 /* start WEP IV from a random value */ 97 get_random_bytes(&priv->iv, 4); 98 99 return priv; 100 101 fail: 102 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 103 if (priv) { 104 if (priv->tfm) 105 crypto_free_tfm(priv->tfm); 106 kfree(priv); 107 } 108 #else 109 if (priv) { 110 if (priv->tx_tfm) 111 crypto_free_blkcipher(priv->tx_tfm); 112 if (priv->rx_tfm) 113 crypto_free_blkcipher(priv->rx_tfm); 114 kfree(priv); 115 } 116 #endif 117 return NULL; 118 } 119 120 121 static void prism2_wep_deinit(void *priv) 122 { 123 struct prism2_wep_data *_priv = priv; 124 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 125 if (_priv && _priv->tfm) 126 crypto_free_tfm(_priv->tfm); 127 #else 128 if (_priv) { 129 if (_priv->tx_tfm) 130 crypto_free_blkcipher(_priv->tx_tfm); 131 if (_priv->rx_tfm) 132 crypto_free_blkcipher(_priv->rx_tfm); 133 } 134 #endif 135 kfree(priv); 136 } 137 138 /* Perform WEP encryption on given skb that has at least 4 bytes of headroom 139 * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted, 140 * so the payload length increases with 8 bytes. 141 * 142 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) 143 */ 144 static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv) 145 { 146 struct prism2_wep_data *wep = priv; 147 u32 klen, len; 148 u8 key[WEP_KEY_LEN + 3]; 149 u8 *pos; 150 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); 151 #if ( !defined(BUILT_IN_CRYPTO) && ((LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,21)) || (OPENSUSE_SLED)) ) 152 struct blkcipher_desc desc = {.tfm = wep->tx_tfm}; 153 #endif 154 u32 crc; 155 u8 *icv; 156 struct scatterlist sg; 157 if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 || 158 skb->len < hdr_len){ 159 printk("Error!!!headroom=%d tailroom=%d skblen=%d hdr_len=%d\n",skb_headroom(skb),skb_tailroom(skb),skb->len,hdr_len); 160 return -1; 161 } 162 len = skb->len - hdr_len; 163 pos = skb_push(skb, 4); 164 memmove(pos, pos + 4, hdr_len); 165 pos += hdr_len; 166 167 klen = 3 + wep->key_len; 168 169 wep->iv++; 170 171 /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key 172 * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N) 173 * can be used to speedup attacks, so avoid using them. */ 174 if ((wep->iv & 0xff00) == 0xff00) { 175 u8 B = (wep->iv >> 16) & 0xff; 176 if (B >= 3 && B < klen) 177 wep->iv += 0x0100; 178 } 179 180 /* Prepend 24-bit IV to RC4 key and TX frame */ 181 *pos++ = key[0] = (wep->iv >> 16) & 0xff; 182 *pos++ = key[1] = (wep->iv >> 8) & 0xff; 183 *pos++ = key[2] = wep->iv & 0xff; 184 *pos++ = wep->key_idx << 6; 185 186 /* Copy rest of the WEP key (the secret part) */ 187 memcpy(key + 3, wep->key, wep->key_len); 188 189 if (!tcb_desc->bHwSec) 190 { 191 192 /* Append little-endian CRC32 and encrypt it to produce ICV */ 193 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2,5,0)) 194 crc = ~crc32_le(~0, pos, len); 195 #else 196 crc = ~ether_crc_le(len, pos); 197 #endif 198 icv = skb_put(skb, 4); 199 icv[0] = crc; 200 icv[1] = crc >> 8; 201 icv[2] = crc >> 16; 202 icv[3] = crc >> 24; 203 204 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)) 205 sg.page = virt_to_page(pos); 206 sg.offset = offset_in_page(pos); 207 sg.length = len + 4; 208 #else 209 sg_init_one(&sg, pos, len+4); 210 #endif 211 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 212 crypto_cipher_setkey(wep->tfm, key, klen); 213 crypto_cipher_encrypt(wep->tfm, &sg, &sg, len + 4); 214 return 0; 215 #else 216 crypto_blkcipher_setkey(wep->tx_tfm, key, klen); 217 return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4); 218 #endif 219 } 220 221 return 0; 222 } 223 224 225 /* Perform WEP decryption on given buffer. Buffer includes whole WEP part of 226 * the frame: IV (4 bytes), encrypted payload (including SNAP header), 227 * ICV (4 bytes). len includes both IV and ICV. 228 * 229 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on 230 * failure. If frame is OK, IV and ICV will be removed. 231 */ 232 static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 233 { 234 struct prism2_wep_data *wep = priv; 235 u32 klen, plen; 236 u8 key[WEP_KEY_LEN + 3]; 237 u8 keyidx, *pos; 238 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); 239 #if ( !defined(BUILT_IN_CRYPTO) && ((LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,21)) || (OPENSUSE_SLED)) ) 240 struct blkcipher_desc desc = {.tfm = wep->rx_tfm}; 241 #endif 242 u32 crc; 243 u8 icv[4]; 244 struct scatterlist sg; 245 if (skb->len < hdr_len + 8) 246 return -1; 247 248 pos = skb->data + hdr_len; 249 key[0] = *pos++; 250 key[1] = *pos++; 251 key[2] = *pos++; 252 keyidx = *pos++ >> 6; 253 if (keyidx != wep->key_idx) 254 return -1; 255 256 klen = 3 + wep->key_len; 257 258 /* Copy rest of the WEP key (the secret part) */ 259 memcpy(key + 3, wep->key, wep->key_len); 260 261 /* Apply RC4 to data and compute CRC32 over decrypted data */ 262 plen = skb->len - hdr_len - 8; 263 264 if (!tcb_desc->bHwSec) 265 { 266 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)) 267 sg.page = virt_to_page(pos); 268 sg.offset = offset_in_page(pos); 269 sg.length = plen + 4; 270 #else 271 sg_init_one(&sg, pos, plen+4); 272 #endif 273 #if ( defined(BUILT_IN_CRYPTO) || ((LINUX_VERSION_CODE < KERNEL_VERSION(2,6,21)) && (!OPENSUSE_SLED)) ) 274 crypto_cipher_setkey(wep->tfm, key, klen); 275 crypto_cipher_decrypt(wep->tfm, &sg, &sg, plen + 4); 276 #else 277 crypto_blkcipher_setkey(wep->rx_tfm, key, klen); 278 if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4)) 279 return -7; 280 #endif 281 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2,5,0)) 282 crc = ~crc32_le(~0, pos, plen); 283 #else 284 crc = ~ether_crc_le(plen, pos); 285 #endif 286 icv[0] = crc; 287 icv[1] = crc >> 8; 288 icv[2] = crc >> 16; 289 icv[3] = crc >> 24; 290 if (memcmp(icv, pos + plen, 4) != 0) { 291 /* ICV mismatch - drop frame */ 292 return -2; 293 } 294 } 295 /* Remove IV and ICV */ 296 memmove(skb->data + 4, skb->data, hdr_len); 297 skb_pull(skb, 4); 298 skb_trim(skb, skb->len - 4); 299 300 return 0; 301 } 302 303 304 static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv) 305 { 306 struct prism2_wep_data *wep = priv; 307 308 if (len < 0 || len > WEP_KEY_LEN) 309 return -1; 310 311 memcpy(wep->key, key, len); 312 wep->key_len = len; 313 314 return 0; 315 } 316 317 318 static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv) 319 { 320 struct prism2_wep_data *wep = priv; 321 322 if (len < wep->key_len) 323 return -1; 324 325 memcpy(key, wep->key, wep->key_len); 326 327 return wep->key_len; 328 } 329 330 331 static char * prism2_wep_print_stats(char *p, void *priv) 332 { 333 struct prism2_wep_data *wep = priv; 334 p += sprintf(p, "key[%d] alg=WEP len=%d\n", 335 wep->key_idx, wep->key_len); 336 return p; 337 } 338 339 340 static struct rtllib_crypto_ops rtllib_crypt_wep = { 341 .name = "WEP", 342 .init = prism2_wep_init, 343 .deinit = prism2_wep_deinit, 344 .encrypt_mpdu = prism2_wep_encrypt, 345 .decrypt_mpdu = prism2_wep_decrypt, 346 .encrypt_msdu = NULL, 347 .decrypt_msdu = NULL, 348 .set_key = prism2_wep_set_key, 349 .get_key = prism2_wep_get_key, 350 .print_stats = prism2_wep_print_stats, 351 .extra_prefix_len = 4, /* IV */ 352 .extra_postfix_len = 4, /* ICV */ 353 .owner = THIS_MODULE, 354 }; 355 356 357 int __init rtllib_crypto_wep_init(void) 358 { 359 return rtllib_register_crypto_ops(&rtllib_crypt_wep); 360 } 361 362 363 void __exit rtllib_crypto_wep_exit(void) 364 { 365 rtllib_unregister_crypto_ops(&rtllib_crypt_wep); 366 } 367 368 void rtllib_wep_null(void) 369 { 370 return; 371 } 372