// SPDX-License-Identifier: GPL-2.0
|
/*
|
* Host AP crypt: host-based WEP encryption implementation for Host AP driver
|
*
|
* Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
|
*/
|
|
#include <crypto/arc4.h>
|
#include <linux/fips.h>
|
#include <linux/module.h>
|
#include <linux/init.h>
|
#include <linux/slab.h>
|
#include <linux/random.h>
|
#include <linux/skbuff.h>
|
#include <linux/string.h>
|
#include "rtllib.h"
|
|
#include <linux/crc32.h>
|
|
struct prism2_wep_data {
|
u32 iv;
|
#define WEP_KEY_LEN 13
|
u8 key[WEP_KEY_LEN + 1];
|
u8 key_len;
|
u8 key_idx;
|
struct arc4_ctx rx_ctx_arc4;
|
struct arc4_ctx tx_ctx_arc4;
|
};
|
|
|
static void *prism2_wep_init(int keyidx)
|
{
|
struct prism2_wep_data *priv;
|
|
if (fips_enabled)
|
return NULL;
|
|
priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
|
if (priv == NULL)
|
return NULL;
|
priv->key_idx = keyidx;
|
|
/* start WEP IV from a random value */
|
get_random_bytes(&priv->iv, 4);
|
|
return priv;
|
}
|
|
|
static void prism2_wep_deinit(void *priv)
|
{
|
kfree_sensitive(priv);
|
}
|
|
/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
|
* for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
|
* so the payload length increases with 8 bytes.
|
*
|
* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
|
*/
|
static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
|
{
|
struct prism2_wep_data *wep = priv;
|
u32 klen, len;
|
u8 key[WEP_KEY_LEN + 3];
|
u8 *pos;
|
struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
|
MAX_DEV_ADDR_SIZE);
|
u32 crc;
|
u8 *icv;
|
|
if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
|
skb->len < hdr_len){
|
pr_err("Error!!! headroom=%d tailroom=%d skblen=%d hdr_len=%d\n",
|
skb_headroom(skb), skb_tailroom(skb), skb->len, hdr_len);
|
return -1;
|
}
|
len = skb->len - hdr_len;
|
pos = skb_push(skb, 4);
|
memmove(pos, pos + 4, hdr_len);
|
pos += hdr_len;
|
|
klen = 3 + wep->key_len;
|
|
wep->iv++;
|
|
/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
|
* scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
|
* can be used to speedup attacks, so avoid using them.
|
*/
|
if ((wep->iv & 0xff00) == 0xff00) {
|
u8 B = (wep->iv >> 16) & 0xff;
|
|
if (B >= 3 && B < klen)
|
wep->iv += 0x0100;
|
}
|
|
/* Prepend 24-bit IV to RC4 key and TX frame */
|
*pos++ = key[0] = (wep->iv >> 16) & 0xff;
|
*pos++ = key[1] = (wep->iv >> 8) & 0xff;
|
*pos++ = key[2] = wep->iv & 0xff;
|
*pos++ = wep->key_idx << 6;
|
|
/* Copy rest of the WEP key (the secret part) */
|
memcpy(key + 3, wep->key, wep->key_len);
|
|
if (!tcb_desc->bHwSec) {
|
/* Append little-endian CRC32 and encrypt it to produce ICV */
|
crc = ~crc32_le(~0, pos, len);
|
icv = skb_put(skb, 4);
|
icv[0] = crc;
|
icv[1] = crc >> 8;
|
icv[2] = crc >> 16;
|
icv[3] = crc >> 24;
|
|
arc4_setkey(&wep->tx_ctx_arc4, key, klen);
|
arc4_crypt(&wep->tx_ctx_arc4, pos, pos, len + 4);
|
}
|
|
return 0;
|
}
|
|
|
/* Perform WEP decryption on given struct buffer. Buffer includes whole WEP
|
* part of the frame: IV (4 bytes), encrypted payload (including SNAP header),
|
* ICV (4 bytes). len includes both IV and ICV.
|
*
|
* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
|
* failure. If frame is OK, IV and ICV will be removed.
|
*/
|
static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
|
{
|
struct prism2_wep_data *wep = priv;
|
u32 klen, plen;
|
u8 key[WEP_KEY_LEN + 3];
|
u8 keyidx, *pos;
|
struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
|
MAX_DEV_ADDR_SIZE);
|
u32 crc;
|
u8 icv[4];
|
|
if (skb->len < hdr_len + 8)
|
return -1;
|
|
pos = skb->data + hdr_len;
|
key[0] = *pos++;
|
key[1] = *pos++;
|
key[2] = *pos++;
|
keyidx = *pos++ >> 6;
|
if (keyidx != wep->key_idx)
|
return -1;
|
|
klen = 3 + wep->key_len;
|
|
/* Copy rest of the WEP key (the secret part) */
|
memcpy(key + 3, wep->key, wep->key_len);
|
|
/* Apply RC4 to data and compute CRC32 over decrypted data */
|
plen = skb->len - hdr_len - 8;
|
|
if (!tcb_desc->bHwSec) {
|
arc4_setkey(&wep->rx_ctx_arc4, key, klen);
|
arc4_crypt(&wep->rx_ctx_arc4, pos, pos, plen + 4);
|
|
crc = ~crc32_le(~0, pos, plen);
|
icv[0] = crc;
|
icv[1] = crc >> 8;
|
icv[2] = crc >> 16;
|
icv[3] = crc >> 24;
|
if (memcmp(icv, pos + plen, 4) != 0) {
|
/* ICV mismatch - drop frame */
|
return -2;
|
}
|
}
|
/* Remove IV and ICV */
|
memmove(skb->data + 4, skb->data, hdr_len);
|
skb_pull(skb, 4);
|
skb_trim(skb, skb->len - 4);
|
|
return 0;
|
}
|
|
|
static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv)
|
{
|
struct prism2_wep_data *wep = priv;
|
|
if (len < 0 || len > WEP_KEY_LEN)
|
return -1;
|
|
memcpy(wep->key, key, len);
|
wep->key_len = len;
|
|
return 0;
|
}
|
|
|
static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv)
|
{
|
struct prism2_wep_data *wep = priv;
|
|
if (len < wep->key_len)
|
return -1;
|
|
memcpy(key, wep->key, wep->key_len);
|
|
return wep->key_len;
|
}
|
|
|
static void prism2_wep_print_stats(struct seq_file *m, void *priv)
|
{
|
struct prism2_wep_data *wep = priv;
|
|
seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
|
}
|
|
static struct lib80211_crypto_ops rtllib_crypt_wep = {
|
.name = "R-WEP",
|
.init = prism2_wep_init,
|
.deinit = prism2_wep_deinit,
|
.encrypt_mpdu = prism2_wep_encrypt,
|
.decrypt_mpdu = prism2_wep_decrypt,
|
.encrypt_msdu = NULL,
|
.decrypt_msdu = NULL,
|
.set_key = prism2_wep_set_key,
|
.get_key = prism2_wep_get_key,
|
.print_stats = prism2_wep_print_stats,
|
.extra_mpdu_prefix_len = 4, /* IV */
|
.extra_mpdu_postfix_len = 4, /* ICV */
|
.owner = THIS_MODULE,
|
};
|
|
|
static int __init rtllib_crypto_wep_init(void)
|
{
|
return lib80211_register_crypto_ops(&rtllib_crypt_wep);
|
}
|
|
|
static void __exit rtllib_crypto_wep_exit(void)
|
{
|
lib80211_unregister_crypto_ops(&rtllib_crypt_wep);
|
}
|
|
module_init(rtllib_crypto_wep_init);
|
module_exit(rtllib_crypto_wep_exit);
|
|
MODULE_LICENSE("GPL");
|
