linux/net/mac80211/wep.c
Johannes Berg 8f20fc2498 [MAC80211]: embed key conf in key, fix driver interface
This patch embeds the struct ieee80211_key_conf into struct ieee80211_key
and thus avoids allocations and having data present twice.

This required some more changes:
 1) The removal of the IEEE80211_KEY_DEFAULT_TX_KEY key flag.
    This flag isn't used by drivers nor should it be since
    we have a set_key_idx() callback. Maybe that callback needs
    to be extended to include the key conf, but only a driver that
    requires it will tell.
 2) The removal of the IEEE80211_KEY_DEFAULT_WEP_ONLY key flag.
    This flag is global, so it shouldn't be passed in the key
    conf structure. Pass it to the function instead.

Also, this patch removes the AID parameter to the set_key() callback
because it is currently unused and the hardware currently cannot know
about the AID anyway. I suspect this was used with some hardware that
actually selected the AID itself, but that functionality was removed.

Additionally, I've removed the ALG_NULL key algorithm since we have
ALG_NONE.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:48:51 -07:00

329 lines
8.1 KiB
C

/*
* Software WEP encryption implementation
* Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
* Copyright 2003, Instant802 Networks, Inc.
*
* 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.
*/
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/random.h>
#include <linux/compiler.h>
#include <linux/crc32.h>
#include <linux/crypto.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <asm/scatterlist.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "wep.h"
int ieee80211_wep_init(struct ieee80211_local *local)
{
/* start WEP IV from a random value */
get_random_bytes(&local->wep_iv, WEP_IV_LEN);
local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(local->wep_tx_tfm))
return -ENOMEM;
local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(local->wep_rx_tfm)) {
crypto_free_blkcipher(local->wep_tx_tfm);
return -ENOMEM;
}
return 0;
}
void ieee80211_wep_free(struct ieee80211_local *local)
{
crypto_free_blkcipher(local->wep_tx_tfm);
crypto_free_blkcipher(local->wep_rx_tfm);
}
static inline int ieee80211_wep_weak_iv(u32 iv, int keylen)
{
/* 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 ((iv & 0xff00) == 0xff00) {
u8 B = (iv >> 16) & 0xff;
if (B >= 3 && B < 3 + keylen)
return 1;
}
return 0;
}
void ieee80211_wep_get_iv(struct ieee80211_local *local,
struct ieee80211_key *key, u8 *iv)
{
local->wep_iv++;
if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen))
local->wep_iv += 0x0100;
if (!iv)
return;
*iv++ = (local->wep_iv >> 16) & 0xff;
*iv++ = (local->wep_iv >> 8) & 0xff;
*iv++ = local->wep_iv & 0xff;
*iv++ = key->conf.keyidx << 6;
}
u8 * ieee80211_wep_add_iv(struct ieee80211_local *local,
struct sk_buff *skb,
struct ieee80211_key *key)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 fc;
int hdrlen;
u8 *newhdr;
fc = le16_to_cpu(hdr->frame_control);
fc |= IEEE80211_FCTL_PROTECTED;
hdr->frame_control = cpu_to_le16(fc);
if ((skb_headroom(skb) < WEP_IV_LEN ||
skb_tailroom(skb) < WEP_ICV_LEN)) {
I802_DEBUG_INC(local->tx_expand_skb_head);
if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN,
GFP_ATOMIC)))
return NULL;
}
hdrlen = ieee80211_get_hdrlen(fc);
newhdr = skb_push(skb, WEP_IV_LEN);
memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
ieee80211_wep_get_iv(local, key, newhdr + hdrlen);
return newhdr + hdrlen;
}
void ieee80211_wep_remove_iv(struct ieee80211_local *local,
struct sk_buff *skb,
struct ieee80211_key *key)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 fc;
int hdrlen;
fc = le16_to_cpu(hdr->frame_control);
hdrlen = ieee80211_get_hdrlen(fc);
memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
skb_pull(skb, WEP_IV_LEN);
}
/* Perform WEP encryption using given key. data buffer must have tailroom
* for 4-byte ICV. data_len must not include this ICV. Note: this function
* does _not_ add IV. data = RC4(data | CRC32(data)) */
void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
size_t klen, u8 *data, size_t data_len)
{
struct blkcipher_desc desc = { .tfm = tfm };
struct scatterlist sg;
__le32 *icv;
icv = (__le32 *)(data + data_len);
*icv = cpu_to_le32(~crc32_le(~0, data, data_len));
crypto_blkcipher_setkey(tfm, rc4key, klen);
sg.page = virt_to_page(data);
sg.offset = offset_in_page(data);
sg.length = data_len + WEP_ICV_LEN;
crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
}
/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
* beginning of the buffer 4 bytes of extra space (ICV) in the end of the
* buffer will be added. 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))
*/
int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb,
struct ieee80211_key *key)
{
u32 klen;
u8 *rc4key, *iv;
size_t len;
if (!key || key->conf.alg != ALG_WEP)
return -1;
klen = 3 + key->conf.keylen;
rc4key = kmalloc(klen, GFP_ATOMIC);
if (!rc4key)
return -1;
iv = ieee80211_wep_add_iv(local, skb, key);
if (!iv) {
kfree(rc4key);
return -1;
}
len = skb->len - (iv + WEP_IV_LEN - skb->data);
/* Prepend 24-bit IV to RC4 key */
memcpy(rc4key, iv, 3);
/* Copy rest of the WEP key (the secret part) */
memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
/* Add room for ICV */
skb_put(skb, WEP_ICV_LEN);
ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen,
iv + WEP_IV_LEN, len);
kfree(rc4key);
return 0;
}
/* Perform WEP decryption using given key. data buffer includes encrypted
* payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
* Return 0 on success and -1 on ICV mismatch. */
int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
size_t klen, u8 *data, size_t data_len)
{
struct blkcipher_desc desc = { .tfm = tfm };
struct scatterlist sg;
__le32 crc;
crypto_blkcipher_setkey(tfm, rc4key, klen);
sg.page = virt_to_page(data);
sg.offset = offset_in_page(data);
sg.length = data_len + WEP_ICV_LEN;
crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
crc = cpu_to_le32(~crc32_le(~0, data, data_len));
if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0)
/* ICV mismatch */
return -1;
return 0;
}
/* Perform WEP decryption on given skb. Buffer includes whole WEP part of
* the frame: IV (4 bytes), encrypted payload (including SNAP header),
* ICV (4 bytes). skb->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, i.e., decrypted payload
* is moved to the beginning of the skb and skb length will be reduced.
*/
int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb,
struct ieee80211_key *key)
{
u32 klen;
u8 *rc4key;
u8 keyidx;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 fc;
int hdrlen;
size_t len;
int ret = 0;
fc = le16_to_cpu(hdr->frame_control);
if (!(fc & IEEE80211_FCTL_PROTECTED))
return -1;
hdrlen = ieee80211_get_hdrlen(fc);
if (skb->len < 8 + hdrlen)
return -1;
len = skb->len - hdrlen - 8;
keyidx = skb->data[hdrlen + 3] >> 6;
if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP)
return -1;
klen = 3 + key->conf.keylen;
rc4key = kmalloc(klen, GFP_ATOMIC);
if (!rc4key)
return -1;
/* Prepend 24-bit IV to RC4 key */
memcpy(rc4key, skb->data + hdrlen, 3);
/* Copy rest of the WEP key (the secret part) */
memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
skb->data + hdrlen + WEP_IV_LEN,
len)) {
printk(KERN_DEBUG "WEP decrypt failed (ICV)\n");
ret = -1;
}
kfree(rc4key);
/* Trim ICV */
skb_trim(skb, skb->len - WEP_ICV_LEN);
/* Remove IV */
memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
skb_pull(skb, WEP_IV_LEN);
return ret;
}
int ieee80211_wep_get_keyidx(struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 fc;
int hdrlen;
fc = le16_to_cpu(hdr->frame_control);
if (!(fc & IEEE80211_FCTL_PROTECTED))
return -1;
hdrlen = ieee80211_get_hdrlen(fc);
if (skb->len < 8 + hdrlen)
return -1;
return skb->data[hdrlen + 3] >> 6;
}
u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 fc;
int hdrlen;
u8 *ivpos;
u32 iv;
fc = le16_to_cpu(hdr->frame_control);
if (!(fc & IEEE80211_FCTL_PROTECTED))
return NULL;
hdrlen = ieee80211_get_hdrlen(fc);
ivpos = skb->data + hdrlen;
iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
if (ieee80211_wep_weak_iv(iv, key->conf.keylen))
return ivpos;
return NULL;
}