kernel-fxtec-pro1x/net/ieee80211/ieee80211_crypt_wep.c
James Ketrenos 1264fc0498 [PATCH] ieee80211: Fix TKIP, repeated fragmentation problem, and payload_size reporting
tree 8428e9f510e6ad6c77baec89cb57374842abf733
parent d78bfd3ddae9c422dd350159110f9c4d7cfc50de
author Liu Hong <hong.liu@intel.com> 1124446520 -0500
committer James Ketrenos <jketreno@linux.intel.com> 1127313183 -0500

Fix TKIP, repeated fragmentation problem, and payload_size reporting

1. TKIP encryption
    Originally, TKIP encryption issues msdu + mpdu encryption on every
    fragment. Change the behavior to msdu encryption on the whole
    packet, then mpdu encryption on every fragment.

2. Avoid repeated fragmentation when !host_encrypt.
    We only need do fragmentation when using host encryption. Otherwise
    we only need pass the whole packet to driver, letting driver do the
    fragmentation.

3. change the txb->payload_size to correct value
    FW will use this value to determine whether to do fragmentation. If
    we pass the wrong value, fw may cut on the wrong bound which will
    make decryption fail when we do host encryption.

NOTE:  This requires changing drivers (hostap) that have
extra_prefix_len used within them (structure member name change).

Signed-off-by: Hong Liu <liu.hong@intel.com>
Signed-off-by: James Ketrenos <jketreno@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
2005-09-21 23:02:31 -04:00

258 lines
6.2 KiB
C

/*
* Host AP crypt: host-based WEP encryption implementation for Host AP driver
*
* Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. See README and COPYING for
* more details.
*/
#include <linux/config.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <asm/string.h>
#include <net/ieee80211.h>
#include <linux/crypto.h>
#include <asm/scatterlist.h>
#include <linux/crc32.h>
MODULE_AUTHOR("Jouni Malinen");
MODULE_DESCRIPTION("Host AP crypt: WEP");
MODULE_LICENSE("GPL");
struct prism2_wep_data {
u32 iv;
#define WEP_KEY_LEN 13
u8 key[WEP_KEY_LEN + 1];
u8 key_len;
u8 key_idx;
struct crypto_tfm *tfm;
};
static void *prism2_wep_init(struct ieee80211_device *ieee, int keyidx)
{
struct prism2_wep_data *priv;
priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
if (priv == NULL)
goto fail;
memset(priv, 0, sizeof(*priv));
priv->key_idx = keyidx;
priv->tfm = crypto_alloc_tfm("arc4", 0);
if (priv->tfm == NULL) {
printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
"crypto API arc4\n");
goto fail;
}
/* start WEP IV from a random value */
get_random_bytes(&priv->iv, 4);
return priv;
fail:
if (priv) {
if (priv->tfm)
crypto_free_tfm(priv->tfm);
kfree(priv);
}
return NULL;
}
static void prism2_wep_deinit(void *priv)
{
struct prism2_wep_data *_priv = priv;
if (_priv && _priv->tfm)
crypto_free_tfm(_priv->tfm);
kfree(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 crc, klen, len;
u8 key[WEP_KEY_LEN + 3];
u8 *pos, *icv;
struct scatterlist sg;
if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
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);
/* 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;
crypto_cipher_setkey(wep->tfm, key, klen);
sg.page = virt_to_page(pos);
sg.offset = offset_in_page(pos);
sg.length = len + 4;
crypto_cipher_encrypt(wep->tfm, &sg, &sg, len + 4);
return 0;
}
/* Perform WEP decryption on given 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 crc, klen, plen;
u8 key[WEP_KEY_LEN + 3];
u8 keyidx, *pos, icv[4];
struct scatterlist sg;
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;
crypto_cipher_setkey(wep->tfm, key, klen);
sg.page = virt_to_page(pos);
sg.offset = offset_in_page(pos);
sg.length = plen + 4;
crypto_cipher_decrypt(wep->tfm, &sg, &sg, 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 char *prism2_wep_print_stats(char *p, void *priv)
{
struct prism2_wep_data *wep = priv;
p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
return p;
}
static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
.name = "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 ieee80211_crypto_wep_init(void)
{
return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
}
static void __exit ieee80211_crypto_wep_exit(void)
{
ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
}
module_init(ieee80211_crypto_wep_init);
module_exit(ieee80211_crypto_wep_exit);