lib80211: absorb crypto bits from net/ieee80211

These bits are shared already between ipw2x00 and hostap, and could
probably be shared both more cleanly and with other drivers.  This
commit simply relocates the code to lib80211 and adjusts the drivers
appropriately.

Signed-off-by: John W. Linville <linville@tuxdriver.com>

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 000000000000..6d41e05ca33b
--- /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);