1 files changed, 296 insertions, 0 deletions
diff --git a/net/wireless/lib80211_crypt_wep.c b/net/wireless/lib80211_crypt_wep.c
new file mode 100644
index 0000000..6d41e05
--- /dev/null
+++ b/net/wireless/lib80211_crypt_wep.c
@@ -0,0 +1,296 @@
+/*
+ * lib80211 crypt: host-based WEP encryption implementation for lib80211
+ *
+ * Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
+ *
+ * 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. See README and COPYING for
+ * more details.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <linux/skbuff.h>
+#include <linux/mm.h>
+#include <asm/string.h>
+
+#include <net/lib80211.h>
+
+#include <linux/crypto.h>
+#include <linux/crc32.h>
+
+MODULE_AUTHOR("Jouni Malinen");
+MODULE_DESCRIPTION("lib80211 crypt: WEP");
+MODULE_LICENSE("GPL");
+
+struct lib80211_wep_data {
+	u32 iv;
+#define WEP_KEY_LEN 13
+	u8 key[WEP_KEY_LEN + 1];
+	u8 key_len;
+	u8 key_idx;
+	struct crypto_blkcipher *tx_tfm;
+	struct crypto_blkcipher *rx_tfm;
+};
+
+static void *lib80211_wep_init(int keyidx)
+{
+	struct lib80211_wep_data *priv;
+
+	priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
+	if (priv == NULL)
+		goto fail;
+	priv->key_idx = keyidx;
+
+	priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(priv->tx_tfm)) {
+		printk(KERN_DEBUG "lib80211_crypt_wep: could not allocate "
+		       "crypto API arc4\n");
+		priv->tx_tfm = NULL;
+		goto fail;
+	}
+
+	priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(priv->rx_tfm)) {
+		printk(KERN_DEBUG "lib80211_crypt_wep: could not allocate "
+		       "crypto API arc4\n");
+		priv->rx_tfm = NULL;
+		goto fail;
+	}
+	/* start WEP IV from a random value */
+	get_random_bytes(&priv->iv, 4);
+
+	return priv;
+
+      fail:
+	if (priv) {
+		if (priv->tx_tfm)
+			crypto_free_blkcipher(priv->tx_tfm);
+		if (priv->rx_tfm)
+			crypto_free_blkcipher(priv->rx_tfm);
+		kfree(priv);
+	}
+	return NULL;
+}
+
+static void lib80211_wep_deinit(void *priv)
+{
+	struct lib80211_wep_data *_priv = priv;
+	if (_priv) {
+		if (_priv->tx_tfm)
+			crypto_free_blkcipher(_priv->tx_tfm);
+		if (_priv->rx_tfm)
+			crypto_free_blkcipher(_priv->rx_tfm);
+	}
+	kfree(priv);
+}
+
+/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
+static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
+			       u8 *key, int keylen, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+	u32 klen, len;
+	u8 *pos;
+
+	if (skb_headroom(skb) < 4 || skb->len < hdr_len)
+		return -1;
+
+	len = skb->len - hdr_len;
+	pos = skb_push(skb, 4);
+	memmove(pos, pos + 4, hdr_len);
+	pos += hdr_len;
+
+	klen = 3 + wep->key_len;
+
+	wep->iv++;
+
+	/* 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 ((wep->iv & 0xff00) == 0xff00) {
+		u8 B = (wep->iv >> 16) & 0xff;
+		if (B >= 3 && B < klen)
+			wep->iv += 0x0100;
+	}
+
+	/* Prepend 24-bit IV to RC4 key and TX frame */
+	*pos++ = (wep->iv >> 16) & 0xff;
+	*pos++ = (wep->iv >> 8) & 0xff;
+	*pos++ = wep->iv & 0xff;
+	*pos++ = wep->key_idx << 6;
+
+	return 0;
+}
+
+/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
+ * for IV and 4 bytes of tailroom for ICV. 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))
+ */
+static int lib80211_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+	struct blkcipher_desc desc = { .tfm = wep->tx_tfm };
+	u32 crc, klen, len;
+	u8 *pos, *icv;
+	struct scatterlist sg;
+	u8 key[WEP_KEY_LEN + 3];
+
+	/* other checks are in lib80211_wep_build_iv */
+	if (skb_tailroom(skb) < 4)
+		return -1;
+
+	/* add the IV to the frame */
+	if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
+		return -1;
+
+	/* Copy the IV into the first 3 bytes of the key */
+	skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
+
+	/* Copy rest of the WEP key (the secret part) */
+	memcpy(key + 3, wep->key, wep->key_len);
+
+	len = skb->len - hdr_len - 4;
+	pos = skb->data + hdr_len + 4;
+	klen = 3 + wep->key_len;
+
+	/* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
+	crc = ~crc32_le(~0, pos, len);
+	icv = skb_put(skb, 4);
+	icv[0] = crc;
+	icv[1] = crc >> 8;
+	icv[2] = crc >> 16;
+	icv[3] = crc >> 24;
+
+	crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
+	sg_init_one(&sg, pos, len + 4);
+	return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
+}
+
+/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
+ * the frame: IV (4 bytes), encrypted payload (including SNAP header),
+ * ICV (4 bytes). 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.
+ */
+static int lib80211_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+	struct blkcipher_desc desc = { .tfm = wep->rx_tfm };
+	u32 crc, klen, plen;
+	u8 key[WEP_KEY_LEN + 3];
+	u8 keyidx, *pos, icv[4];
+	struct scatterlist sg;
+
+	if (skb->len < hdr_len + 8)
+		return -1;
+
+	pos = skb->data + hdr_len;
+	key[0] = *pos++;
+	key[1] = *pos++;
+	key[2] = *pos++;
+	keyidx = *pos++ >> 6;
+	if (keyidx != wep->key_idx)
+		return -1;
+
+	klen = 3 + wep->key_len;
+
+	/* Copy rest of the WEP key (the secret part) */
+	memcpy(key + 3, wep->key, wep->key_len);
+
+	/* Apply RC4 to data and compute CRC32 over decrypted data */
+	plen = skb->len - hdr_len - 8;
+
+	crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
+	sg_init_one(&sg, pos, plen + 4);
+	if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
+		return -7;
+
+	crc = ~crc32_le(~0, pos, plen);
+	icv[0] = crc;
+	icv[1] = crc >> 8;
+	icv[2] = crc >> 16;
+	icv[3] = crc >> 24;
+	if (memcmp(icv, pos + plen, 4) != 0) {
+		/* ICV mismatch - drop frame */
+		return -2;
+	}
+
+	/* Remove IV and ICV */
+	memmove(skb->data + 4, skb->data, hdr_len);
+	skb_pull(skb, 4);
+	skb_trim(skb, skb->len - 4);
+
+	return 0;
+}
+
+static int lib80211_wep_set_key(void *key, int len, u8 * seq, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+
+	if (len < 0 || len > WEP_KEY_LEN)
+		return -1;
+
+	memcpy(wep->key, key, len);
+	wep->key_len = len;
+
+	return 0;
+}
+
+static int lib80211_wep_get_key(void *key, int len, u8 * seq, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+
+	if (len < wep->key_len)
+		return -1;
+
+	memcpy(key, wep->key, wep->key_len);
+
+	return wep->key_len;
+}
+
+static char *lib80211_wep_print_stats(char *p, void *priv)
+{
+	struct lib80211_wep_data *wep = priv;
+	p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
+	return p;
+}
+
+static struct lib80211_crypto_ops lib80211_crypt_wep = {
+	.name = "WEP",
+	.init = lib80211_wep_init,
+	.deinit = lib80211_wep_deinit,
+	.build_iv = lib80211_wep_build_iv,
+	.encrypt_mpdu = lib80211_wep_encrypt,
+	.decrypt_mpdu = lib80211_wep_decrypt,
+	.encrypt_msdu = NULL,
+	.decrypt_msdu = NULL,
+	.set_key = lib80211_wep_set_key,
+	.get_key = lib80211_wep_get_key,
+	.print_stats = lib80211_wep_print_stats,
+	.extra_mpdu_prefix_len = 4,	/* IV */
+	.extra_mpdu_postfix_len = 4,	/* ICV */
+	.owner = THIS_MODULE,
+};
+
+static int __init lib80211_crypto_wep_init(void)
+{
+	return lib80211_register_crypto_ops(&lib80211_crypt_wep);
+}
+
+static void __exit lib80211_crypto_wep_exit(void)
+{
+	lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
+}
+
+module_init(lib80211_crypto_wep_init);
+module_exit(lib80211_crypto_wep_exit);