net/mac80211/wep.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Software WEP encryption implementation
  * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
  * Copyright 2003, Instant802 Networks, Inc.
  * Copyright (C) 2023 Intel Corporation
  */

 #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 <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/unaligned.h>

 #include <net/mac80211.h>
 #include "ieee80211_i.h"
 #include "wep.h"


 void ieee80211_wep_init(struct ieee80211_local *local)
 {
 	/* start WEP IV from a random value */
 	get_random_bytes(&local->wep_iv, IEEE80211_WEP_IV_LEN);
 }

 static inline bool 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 true;
 	}
 	return false;
 }


 static void ieee80211_wep_get_iv(struct ieee80211_local *local,
 				 int keylen, int keyidx, u8 *iv)
 {
 	local->wep_iv++;
 	if (ieee80211_wep_weak_iv(local->wep_iv, 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++ = keyidx << 6;
 }


 static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
 				struct sk_buff *skb,
 				int keylen, int keyidx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 	unsigned int hdrlen;
 	u8 *newhdr;

 	hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);

 	if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN))
 		return NULL;

 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 	newhdr = skb_push(skb, IEEE80211_WEP_IV_LEN);
 	memmove(newhdr, newhdr + IEEE80211_WEP_IV_LEN, hdrlen);

 	/* the HW only needs room for the IV, but not the actual IV */
 	if (info->control.hw_key &&
 	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
 		return newhdr + hdrlen;

 	ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
 	return newhdr + hdrlen;
 }


 static 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;
 	unsigned int hdrlen;

 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
 	skb_pull(skb, IEEE80211_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)) */
 int ieee80211_wep_encrypt_data(struct arc4_ctx *ctx, u8 *rc4key,
 			       size_t klen, u8 *data, size_t data_len)
 {
 	__le32 icv;

 	icv = cpu_to_le32(~crc32_le(~0, data, data_len));
 	put_unaligned(icv, (__le32 *)(data + data_len));

 	arc4_setkey(ctx, rc4key, klen);
 	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
 	memzero_explicit(ctx, sizeof(*ctx));

 	return 0;
 }


 /* 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,
 			  const u8 *key, int keylen, int keyidx)
 {
 	u8 *iv;
 	size_t len;
 	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];

 	if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN))
 		return -1;

 	iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
 	if (!iv)
 		return -1;

 	len = skb->len - (iv + IEEE80211_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, keylen);

 	/* Add room for ICV */
 	skb_put(skb, IEEE80211_WEP_ICV_LEN);

 	return ieee80211_wep_encrypt_data(&local->wep_tx_ctx, rc4key, keylen + 3,
 					  iv + IEEE80211_WEP_IV_LEN, len);
 }


 /* 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 arc4_ctx *ctx, u8 *rc4key,
 			       size_t klen, u8 *data, size_t data_len)
 {
 	__le32 crc;

 	arc4_setkey(ctx, rc4key, klen);
 	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
 	memzero_explicit(ctx, sizeof(*ctx));

 	crc = cpu_to_le32(~crc32_le(~0, data, data_len));
 	if (memcmp(&crc, data + data_len, IEEE80211_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.
  */
 static int ieee80211_wep_decrypt(struct ieee80211_local *local,
 				 struct sk_buff *skb,
 				 struct ieee80211_key *key)
 {
 	u32 klen;
 	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
 	u8 keyidx;
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	unsigned int hdrlen;
 	size_t len;
 	int ret = 0;

 	if (!ieee80211_has_protected(hdr->frame_control))
 		return -1;

 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 	if (skb->len < hdrlen + IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN)
 		return -1;

 	len = skb->len - hdrlen - IEEE80211_WEP_IV_LEN - IEEE80211_WEP_ICV_LEN;

 	keyidx = skb->data[hdrlen + 3] >> 6;

 	if (!key || keyidx != key->conf.keyidx)
 		return -1;

 	klen = 3 + key->conf.keylen;

 	/* 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_ctx, rc4key, klen,
 				       skb->data + hdrlen +
 				       IEEE80211_WEP_IV_LEN, len))
 		ret = -1;

 	/* Trim ICV */
 	skb_trim(skb, skb->len - IEEE80211_WEP_ICV_LEN);

 	/* Remove IV */
 	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
 	skb_pull(skb, IEEE80211_WEP_IV_LEN);

 	return ret;
 }

 ieee80211_rx_result
 ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
 {
 	struct sk_buff *skb = rx->skb;
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	__le16 fc = hdr->frame_control;

 	if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc))
 		return RX_CONTINUE;

 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
 		if (skb_linearize(rx->skb))
 			return RX_DROP_U_OOM;
 		if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
 			return RX_DROP_U_WEP_DEC_FAIL;
 	} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
 		if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) +
 					    IEEE80211_WEP_IV_LEN))
 			return RX_DROP_U_NO_IV;
 		ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
 		/* remove ICV */
 		if (!(status->flag & RX_FLAG_ICV_STRIPPED) &&
 		    pskb_trim(rx->skb, rx->skb->len - IEEE80211_WEP_ICV_LEN))
 			return RX_DROP_U_NO_ICV;
 	}

 	return RX_CONTINUE;
 }

 static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 {
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 	struct ieee80211_key_conf *hw_key = info->control.hw_key;

 	if (!hw_key) {
 		if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
 					  tx->key->conf.keylen,
 					  tx->key->conf.keyidx))
 			return -1;
 	} else if ((hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
 		   (hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
 		if (!ieee80211_wep_add_iv(tx->local, skb,
 					  tx->key->conf.keylen,
 					  tx->key->conf.keyidx))
 			return -1;
 	}

 	return 0;
 }

 ieee80211_tx_result
 ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
 {
 	struct sk_buff *skb;

 	ieee80211_tx_set_protected(tx);

 	skb_queue_walk(&tx->skbs, skb) {
 		if (wep_encrypt_skb(tx, skb) < 0) {
 			I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
 			return TX_DROP;
 		}
 	}

 	return TX_CONTINUE;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Software WEP encryption implementation
	* Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
	* Copyright 2003, Instant802 Networks, Inc.
	* Copyright (C) 2023 Intel Corporation
	*/

	#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 <linux/scatterlist.h>
	#include <linux/slab.h>
	#include <linux/unaligned.h>

	#include <net/mac80211.h>
	#include "ieee80211_i.h"
	#include "wep.h"


	void ieee80211_wep_init(struct ieee80211_local *local)
	{
	/* start WEP IV from a random value */
	get_random_bytes(&local->wep_iv, IEEE80211_WEP_IV_LEN);
	}

	static inline bool 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 true;
	}
	return false;
	}


	static void ieee80211_wep_get_iv(struct ieee80211_local *local,
	int keylen, int keyidx, u8 *iv)
	{
	local->wep_iv++;
	if (ieee80211_wep_weak_iv(local->wep_iv, 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++ = keyidx << 6;
	}


	static u8 ieee80211_wep_add_iv(struct ieee80211_local local,
	struct sk_buff *skb,
	int keylen, int keyidx)
	{
	struct ieee80211_hdr hdr = (struct ieee80211_hdr )skb->data;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	unsigned int hdrlen;
	u8 *newhdr;

	hdr->frame_control \|= cpu_to_le16(IEEE80211_FCTL_PROTECTED);

	if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN))
	return NULL;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	newhdr = skb_push(skb, IEEE80211_WEP_IV_LEN);
	memmove(newhdr, newhdr + IEEE80211_WEP_IV_LEN, hdrlen);

	/* the HW only needs room for the IV, but not the actual IV */
	if (info->control.hw_key &&
	(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
	return newhdr + hdrlen;

	ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
	return newhdr + hdrlen;
	}


	static 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;
	unsigned int hdrlen;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
	skb_pull(skb, IEEE80211_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)) */
	int ieee80211_wep_encrypt_data(struct arc4_ctx ctx, u8 rc4key,
	size_t klen, u8 *data, size_t data_len)
	{
	__le32 icv;

	icv = cpu_to_le32(~crc32_le(~0, data, data_len));
	put_unaligned(icv, (__le32 *)(data + data_len));

	arc4_setkey(ctx, rc4key, klen);
	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
	memzero_explicit(ctx, sizeof(*ctx));

	return 0;
	}


	/* 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,
	const u8 *key, int keylen, int keyidx)
	{
	u8 *iv;
	size_t len;
	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];

	if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN))
	return -1;

	iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
	if (!iv)
	return -1;

	len = skb->len - (iv + IEEE80211_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, keylen);

	/* Add room for ICV */
	skb_put(skb, IEEE80211_WEP_ICV_LEN);

	return ieee80211_wep_encrypt_data(&local->wep_tx_ctx, rc4key, keylen + 3,
	iv + IEEE80211_WEP_IV_LEN, len);
	}


	/* 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 arc4_ctx ctx, u8 rc4key,
	size_t klen, u8 *data, size_t data_len)
	{
	__le32 crc;

	arc4_setkey(ctx, rc4key, klen);
	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
	memzero_explicit(ctx, sizeof(*ctx));

	crc = cpu_to_le32(~crc32_le(~0, data, data_len));
	if (memcmp(&crc, data + data_len, IEEE80211_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.
	*/
	static int ieee80211_wep_decrypt(struct ieee80211_local *local,
	struct sk_buff *skb,
	struct ieee80211_key *key)
	{
	u32 klen;
	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
	u8 keyidx;
	struct ieee80211_hdr hdr = (struct ieee80211_hdr )skb->data;
	unsigned int hdrlen;
	size_t len;
	int ret = 0;

	if (!ieee80211_has_protected(hdr->frame_control))
	return -1;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	if (skb->len < hdrlen + IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN)
	return -1;

	len = skb->len - hdrlen - IEEE80211_WEP_IV_LEN - IEEE80211_WEP_ICV_LEN;

	keyidx = skb->data[hdrlen + 3] >> 6;

	if (!key \|\| keyidx != key->conf.keyidx)
	return -1;

	klen = 3 + key->conf.keylen;

	/* 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_ctx, rc4key, klen,
	skb->data + hdrlen +
	IEEE80211_WEP_IV_LEN, len))
	ret = -1;

	/* Trim ICV */
	skb_trim(skb, skb->len - IEEE80211_WEP_ICV_LEN);

	/* Remove IV */
	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
	skb_pull(skb, IEEE80211_WEP_IV_LEN);

	return ret;
	}

	ieee80211_rx_result
	ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
	{
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	struct ieee80211_hdr hdr = (struct ieee80211_hdr )skb->data;
	__le16 fc = hdr->frame_control;

	if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc))
	return RX_CONTINUE;

	if (!(status->flag & RX_FLAG_DECRYPTED)) {
	if (skb_linearize(rx->skb))
	return RX_DROP_U_OOM;
	if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
	return RX_DROP_U_WEP_DEC_FAIL;
	} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
	if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) +
	IEEE80211_WEP_IV_LEN))
	return RX_DROP_U_NO_IV;
	ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
	/* remove ICV */
	if (!(status->flag & RX_FLAG_ICV_STRIPPED) &&
	pskb_trim(rx->skb, rx->skb->len - IEEE80211_WEP_ICV_LEN))
	return RX_DROP_U_NO_ICV;
	}

	return RX_CONTINUE;
	}

	static int wep_encrypt_skb(struct ieee80211_tx_data tx, struct sk_buff skb)
	{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct ieee80211_key_conf *hw_key = info->control.hw_key;

	if (!hw_key) {
	if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
	tx->key->conf.keylen,
	tx->key->conf.keyidx))
	return -1;
	} else if ((hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) \|\|
	(hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
	if (!ieee80211_wep_add_iv(tx->local, skb,
	tx->key->conf.keylen,
	tx->key->conf.keyidx))
	return -1;
	}

	return 0;
	}

	ieee80211_tx_result
	ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
	{
	struct sk_buff *skb;

	ieee80211_tx_set_protected(tx);

	skb_queue_walk(&tx->skbs, skb) {
	if (wep_encrypt_skb(tx, skb) < 0) {
	I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
	return TX_DROP;
	}
	}

	return TX_CONTINUE;
	}