1 files changed, 328 insertions, 0 deletions
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
new file mode 100644
index 00000000000..1ad3d75281c
--- /dev/null
+++ b/net/mac80211/wep.c
@@ -0,0 +1,328 @@
+/*
+ * 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->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->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->alg != ALG_WEP)
+		return -1;
+
+	klen = 3 + key->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->key, key->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->keyidx || key->alg != ALG_WEP)
+		return -1;
+
+	klen = 3 + key->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->key, key->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->keylen))
+		return ivpos;
+
+	return NULL;
+}