1 files changed, 352 insertions, 0 deletions
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
new file mode 100644
index 00000000..9ebc8d8a
--- /dev/null
+++ b/net/mac80211/wep.c
@@ -0,0 +1,352 @@
+/*
+ * 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 <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <asm/unaligned.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)) {
+		local->wep_rx_tfm = ERR_PTR(-EINVAL);
+		return PTR_ERR(local->wep_tx_tfm);
+	}
+
+	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);
+		local->wep_tx_tfm = ERR_PTR(-EINVAL);
+		return PTR_ERR(local->wep_rx_tfm);
+	}
+
+	return 0;
+}
+
+void ieee80211_wep_free(struct ieee80211_local *local)
+{
+	if (!IS_ERR(local->wep_tx_tfm))
+		crypto_free_blkcipher(local->wep_tx_tfm);
+	if (!IS_ERR(local->wep_rx_tfm))
+		crypto_free_blkcipher(local->wep_rx_tfm);
+}
+
+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;
+	unsigned int hdrlen;
+	u8 *newhdr;
+
+	hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
+
+	if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
+		    skb_headroom(skb) < WEP_IV_LEN))
+		return NULL;
+
+	hdrlen = ieee80211_hdrlen(hdr->frame_control);
+	newhdr = skb_push(skb, WEP_IV_LEN);
+	memmove(newhdr, newhdr + WEP_IV_LEN, 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 + 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)) */
+int 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;
+
+	if (IS_ERR(tfm))
+		return -1;
+
+	icv = cpu_to_le32(~crc32_le(~0, data, data_len));
+	put_unaligned(icv, (__le32 *)(data + data_len));
+
+	crypto_blkcipher_setkey(tfm, rc4key, klen);
+	sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
+	crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
+
+	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];
+
+	iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
+	if (!iv)
+		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, keylen);
+
+	/* Add room for ICV */
+	skb_put(skb, WEP_ICV_LEN);
+
+	return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3,
+					  iv + 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 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;
+
+	if (IS_ERR(tfm))
+		return -1;
+
+	crypto_blkcipher_setkey(tfm, rc4key, klen);
+	sg_init_one(&sg, data, 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.
+ */
+static 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;
+	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 + WEP_IV_LEN + WEP_ICV_LEN)
+		return -1;
+
+	len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
+
+	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))
+		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;
+}
+
+
+bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+	unsigned int hdrlen;
+	u8 *ivpos;
+	u32 iv;
+
+	if (!ieee80211_has_protected(hdr->frame_control))
+		return false;
+
+	hdrlen = ieee80211_hdrlen(hdr->frame_control);
+	ivpos = skb->data + hdrlen;
+	iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
+
+	return ieee80211_wep_weak_iv(iv, key->conf.keylen);
+}
+
+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;
+
+	if (!ieee80211_is_data(hdr->frame_control) &&
+	    !ieee80211_is_auth(hdr->frame_control))
+		return RX_CONTINUE;
+
+	if (!(status->flag & RX_FLAG_DECRYPTED)) {
+		if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
+			return RX_DROP_UNUSABLE;
+	} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
+		ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
+		/* remove ICV */
+		skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
+	}
+
+	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);
+
+	if (!info->control.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 (info->control.hw_key->flags &
+			IEEE80211_KEY_FLAG_GENERATE_IV) {
+		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 = tx->skb;
+	do {
+		if (wep_encrypt_skb(tx, skb) < 0) {
+			I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
+			return TX_DROP;
+		}
+	} while ((skb = skb->next));
+
+	return TX_CONTINUE;
+}