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

#include <netdevice.h>
#include <img_mac80211_types.h>
#include <crc32.h>
#include <linux_crypto.h>
#include <linux_err.h>
#include <linux_scatterlist.h>
#include <mac80211.h>
#include "ieee80211_i.h"
#include "wep.h"
#include <errno.h>

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

	local->wep_tx_tfm = (struct crypto_cipher *)"arc4";
	local->wep_rx_tfm = (struct crypto_cipher *)"arc4";
	return 0;
}

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;
}


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;
}


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;
}


void ieee80211_wep_remove_iv(struct ieee80211_local *local,
				    struct sk_buff *skb,
				    struct ieee80211_key *key)
{
	(void)local;
	(void)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);
}

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_UNUSABLE;
	} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
		if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) +
					    IEEE80211_WEP_IV_LEN))
			return RX_DROP_UNUSABLE;
		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_UNUSABLE;
		rx->skb->trim_len = IEEE80211_WEP_ICV_LEN;
	}

	return RX_CONTINUE;
}

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) {
		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;
}