drivers/qtn/wlan/ieee80211_crypto_wep.c - kernel/quantenna - Git at Google

 /*-
  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * $Id: ieee80211_crypto_wep.c 1721 2006-09-20 08:45:13Z mentor $
  */

 /*
  * IEEE 802.11 WEP crypto support.
  */
 #ifndef AUTOCONF_INCLUDED
 #include <linux/config.h>
 #endif
 #include <linux/version.h>
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/random.h>
 #include <linux/init.h>

 #include "net80211/if_media.h"

 #include "net80211/ieee80211_var.h"

 static void *wep_attach(struct ieee80211vap *, struct ieee80211_key *);
 static void wep_detach(struct ieee80211_key *);
 static int wep_setkey(struct ieee80211_key *);
 static int wep_encap(struct ieee80211_key *, struct sk_buff *, u_int8_t);
 static int wep_decap(struct ieee80211_key *, struct sk_buff *, int);
 static int wep_enmic(struct ieee80211_key *, struct sk_buff *, int);
 static int wep_demic(struct ieee80211_key *, struct sk_buff *, int);

 static const struct ieee80211_cipher wep = {
 	.ic_name	= "WEP",
 	.ic_cipher	= IEEE80211_CIPHER_WEP,
 	.ic_header	= IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
 	.ic_trailer	= IEEE80211_WEP_CRCLEN,
 	.ic_miclen	= 0,
 	.ic_attach	= wep_attach,
 	.ic_detach	= wep_detach,
 	.ic_setkey	= wep_setkey,
 	.ic_encap	= wep_encap,
 	.ic_decap	= wep_decap,
 	.ic_enmic	= wep_enmic,
 	.ic_demic	= wep_demic,
 };

 static int wep_encrypt(struct ieee80211_key *, struct sk_buff *, int);
 static int wep_decrypt(struct ieee80211_key *, struct sk_buff *, int);

 struct wep_ctx {
 	struct ieee80211vap *wc_vap;	/* for diagnostics + statistics */
 	struct ieee80211com *wc_ic;	/* for diagnostics */
 	u_int32_t wc_iv;			/* initial vector for crypto */
 };

 static void *
 wep_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
 {
 	struct wep_ctx *ctx;

 	_MOD_INC_USE(THIS_MODULE, return NULL);

 	MALLOC(ctx, struct wep_ctx *, sizeof(struct wep_ctx),
 		M_DEVBUF, M_NOWAIT | M_ZERO);
 	if (ctx == NULL) {
 		vap->iv_stats.is_crypto_nomem++;
 		_MOD_DEC_USE(THIS_MODULE);
 		return NULL;
 	}

 	ctx->wc_vap = vap;
 	ctx->wc_ic = vap->iv_ic;
 	get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
 	return ctx;
 }

 static void
 wep_detach(struct ieee80211_key *k)
 {
 	struct wep_ctx *ctx = k->wk_private;

 	FREE(ctx, M_DEVBUF);

 	_MOD_DEC_USE(THIS_MODULE);
 }

 static int
 wep_setkey(struct ieee80211_key *k)
 {
 	return k->wk_keylen >= 40 / NBBY;
 }

 #ifndef _BYTE_ORDER
 #error "Don't know native byte order"
 #endif

 /*
  * Add privacy headers appropriate for the specified key.
  */
 static int
 wep_encap(struct ieee80211_key *k, struct sk_buff *skb, u_int8_t keyid)
 {
 	struct wep_ctx *ctx = k->wk_private;
 	struct ieee80211com *ic = ctx->wc_ic;
 	u_int32_t iv;
 	u_int8_t *ivp;
 	int hdrlen;

 	hdrlen = ieee80211_hdrspace(ic, skb->data);

 	/*
 	 * Copy down 802.11 header and add the IV + KeyID.
 	 */
 	ivp = skb_push(skb, wep.ic_header);
 	memmove(ivp, ivp + wep.ic_header, hdrlen);
 	ivp += hdrlen;

 	/*
 	 * XXX
 	 * IV must not duplicate during the lifetime of the key.
 	 * But no mechanism to renew keys is defined in IEEE 802.11
 	 * for WEP.  And the IV may be duplicated at other stations
 	 * because the session key itself is shared.  So we use a
 	 * pseudo random IV for now, though it is not the right way.
 	 *
 	 * NB: Rather than use a strictly random IV we select a
 	 * random one to start and then increment the value for
 	 * each frame.  This is an explicit tradeoff between
 	 * overhead and security.  Given the basic insecurity of
 	 * WEP this seems worthwhile.
 	 */

 	/*
 	 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
 	 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
 	 */
 	iv = ctx->wc_iv;
 	if ((iv & 0xff00) == 0xff00) {
 		int B = (iv & 0xff0000) >> 16;
 		if (3 <= B && B < 16)
 			iv += 0x0100;
 	}
 	ctx->wc_iv = iv + 1;

 	/*
 	 * NB: Preserve byte order of IV for packet
 	 *     sniffers; it doesn't matter otherwise.
 	 */
 #if _BYTE_ORDER == _BIG_ENDIAN
 	ivp[0] = iv >> 0;
 	ivp[1] = iv >> 8;
 	ivp[2] = iv >> 16;
 #else
 	ivp[2] = iv >> 0;
 	ivp[1] = iv >> 8;
 	ivp[0] = iv >> 16;
 #endif
 	ivp[3] = keyid;

 	/*
 	 * Finally, do software encrypt if neeed.
 	 */
 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
 	    !wep_encrypt(k, skb, hdrlen))
 		return 0;

 	return 1;
 }

 /*
  * Add MIC to the frame as needed.
  */
 static int
 wep_enmic(struct ieee80211_key *k, struct sk_buff *skb, int force)
 {
 	return 1;
 }

 /*
  * Validate and strip privacy headers (and trailer) for a
  * received frame.  If necessary, decrypt the frame using
  * the specified key.
  */
 static int
 wep_decap(struct ieee80211_key *k, struct sk_buff *skb, int hdrlen)
 {
 	struct wep_ctx *ctx = k->wk_private;
 	struct ieee80211vap *vap = ctx->wc_vap;
 	struct ieee80211_frame *wh;

 	wh = (struct ieee80211_frame *)skb->data;

 	/*
 	 * Check if the device handled the decrypt in hardware.
 	 * If so we just strip the header; otherwise we need to
 	 * handle the decrypt in software.
 	 */
 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
 	    !wep_decrypt(k, skb, hdrlen)) {
 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
 			"%s", "WEP ICV mismatch on decrypt");
 		vap->iv_stats.is_rx_wepfail++;
 		return 0;
 	}

 	/*
 	 * Copy up 802.11 header and strip crypto bits.
 	 */
 	memmove(skb->data + wep.ic_header, skb->data, hdrlen);
 	skb_pull(skb, wep.ic_header);
 	skb_trim(skb, skb->len - wep.ic_trailer);

 	return 1;
 }

 /*
  * Verify and strip MIC from the frame.
  */
 static int
 wep_demic(struct ieee80211_key *k, struct sk_buff *skb, int hdrlen)
 {
 	return 1;
 }

 static const uint32_t crc32_table[256] = {
 	0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
 	0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
 	0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
 	0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
 	0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
 	0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
 	0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
 	0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
 	0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
 	0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
 	0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
 	0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
 	0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
 	0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
 	0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
 	0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
 	0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
 	0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
 	0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
 	0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
 	0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
 	0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
 	0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
 	0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
 	0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
 	0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
 	0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
 	0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
 	0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
 	0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
 	0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
 	0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
 	0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
 	0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
 	0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
 	0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
 	0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
 	0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
 	0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
 	0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
 	0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
 	0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
 	0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
 	0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
 	0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
 	0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
 	0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
 	0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
 	0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
 	0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
 	0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
 	0x2d02ef8dL
 };

 static int
 wep_encrypt(struct ieee80211_key *key, struct sk_buff *skb0, int hdrlen)
 {
 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
 	struct wep_ctx *ctx = key->wk_private;
 	struct ieee80211vap *vap = ctx->wc_vap;
 	struct sk_buff *skb = skb0;
 	u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
 	uint8_t *icv;
 	uint32_t i, j, k, crc;
 	size_t buflen, data_len;
 	uint8_t S[256];
 	uint8_t *pos;
 	u_int off, keylen;

 	vap->iv_stats.is_crypto_wep++;

 	/* NB: this assumes the header was pulled up */
 	memcpy(rc4key, skb->data + hdrlen, IEEE80211_WEP_IVLEN);
 	memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);

 	/* Setup RC4 state */
 	for (i = 0; i < 256; i++)
 		S[i] = i;
 	j = 0;
 	keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
 	for (i = 0; i < 256; i++) {
 		j = (j + S[i] + rc4key[i % keylen]) & 0xff;
 		S_SWAP(i, j);
 	}

 	off = hdrlen + wep.ic_header;
 	data_len = skb->len - off;

 	/* Compute CRC32 over unencrypted data and apply RC4 to data */
 	crc = ~0;
 	i = j = 0;
 	pos = skb->data + off;
 	buflen = skb->len - off;
 	for (;;) {
 		if (buflen > data_len)
 			buflen = data_len;
 		data_len -= buflen;
 		for (k = 0; k < buflen; k++) {
 			crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
 			i = (i + 1) & 0xff;
 			j = (j + S[i]) & 0xff;
 			S_SWAP(i, j);
 			*pos++ ^= S[(S[i] + S[j]) & 0xff];
 		}
 		if (skb->next == NULL) {
 			if (data_len != 0) {		/* out of data */
 #ifdef IEEE80211_DEBUG
 				const struct ieee80211_frame *wh =
 				    (const struct ieee80211_frame *) skb0->data;
 #endif
 				IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
 					wh->i_addr2,
 					"out of data for WEP (data_len %lu)",
 					(unsigned long) data_len);
 				return 0;
 			}
 			break;
 		}
 		skb = skb->next;
 		pos = skb->data;
 		buflen = skb->len;
 	}
 	crc = ~crc;

 	if (skb_tailroom(skb) < wep.ic_trailer) {
 #ifdef IEEE80211_DEBUG
 		const struct ieee80211_frame *wh =
 			(const struct ieee80211_frame *) skb0->data;
 #endif
 		/* NB: should not happen */
 		IEEE80211_NOTE_MAC(ctx->wc_vap, IEEE80211_MSG_CRYPTO,
 			wh->i_addr1, "no room for %s ICV, tailroom %u",
 			wep.ic_name, skb_tailroom(skb));
 		/* XXX statistic */
 		return 0;
 	}
 	/* Append little-endian CRC32 and encrypt it to produce ICV */
 	icv = skb_put(skb, IEEE80211_WEP_CRCLEN);
 	icv[0] = crc;
 	icv[1] = crc >> 8;
 	icv[2] = crc >> 16;
 	icv[3] = crc >> 24;
 	for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
 		i = (i + 1) & 0xff;
 		j = (j + S[i]) & 0xff;
 		S_SWAP(i, j);
 		icv[k] ^= S[(S[i] + S[j]) & 0xff];
 	}
 	return 1;
 #undef S_SWAP
 }

 static int
 wep_decrypt(struct ieee80211_key *key, struct sk_buff *skb0, int hdrlen)
 {
 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
 	struct wep_ctx *ctx = key->wk_private;
 	struct ieee80211vap *vap = ctx->wc_vap;
 	struct sk_buff *skb = skb0;
 	u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
 	uint8_t icv[IEEE80211_WEP_CRCLEN];
 	uint32_t i, j, k, crc;
 	size_t buflen, data_len;
 	uint8_t S[256];
 	uint8_t *pos;
 	u_int off, keylen;

 	vap->iv_stats.is_crypto_wep++;

 	/* NB: this assumes the header was pulled up */
 	memcpy(rc4key, skb->data + hdrlen, IEEE80211_WEP_IVLEN);
 	memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);

 	/* Setup RC4 state */
 	for (i = 0; i < 256; i++)
 		S[i] = i;
 	j = 0;
 	keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
 	for (i = 0; i < 256; i++) {
 		j = (j + S[i] + rc4key[i % keylen]) & 0xff;
 		S_SWAP(i, j);
 	}

 	off = hdrlen + wep.ic_header;
 	data_len = skb->len - (off + wep.ic_trailer),

 	/* Compute CRC32 over unencrypted data and apply RC4 to data */
 	crc = ~0;
 	i = j = 0;
 	pos = skb->data + off;
 	buflen = skb->len - off;
 	for (;;) {
 		if (buflen > data_len)
 			buflen = data_len;
 		data_len -= buflen;
 		for (k = 0; k < buflen; k++) {
 			i = (i + 1) & 0xff;
 			j = (j + S[i]) & 0xff;
 			S_SWAP(i, j);
 			*pos ^= S[(S[i] + S[j]) & 0xff];
 			crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
 			pos++;
 		}
 		skb = skb->next;
 		if (skb == NULL) {
 			if (data_len != 0) {		/* out of data */
 #ifdef IEEE80211_DEBUG
 				const struct ieee80211_frame *wh =
 					(const struct ieee80211_frame *) skb0->data;
 #endif
 				IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
 					wh->i_addr2,
 					"out of data for WEP (data_len %lu)",
 					(unsigned long) data_len);
 				return 0;
 			}
 			break;
 		}
 		pos = skb->data;
 		buflen = skb->len;
 	}
 	crc = ~crc;

 	/* Encrypt little-endian CRC32 and verify that it matches with
 	 * received ICV */
 	icv[0] = crc;
 	icv[1] = crc >> 8;
 	icv[2] = crc >> 16;
 	icv[3] = crc >> 24;
 	for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
 		i = (i + 1) & 0xff;
 		j = (j + S[i]) & 0xff;
 		S_SWAP(i, j);
 		/* XXX assumes ICV is contiguous in sk_buf */
 		if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
 			/* ICV mismatch - drop frame */
 			return 0;
 		}
 	}
 	return 1;
 #undef S_SWAP
 }

 /*
  * Module glue.
  */

 MODULE_AUTHOR("Errno Consulting, Sam Leffler");
 MODULE_DESCRIPTION("802.11 wireless support: WEP cipher");
 #ifdef MODULE_LICENSE
 MODULE_LICENSE("Dual BSD/GPL");
 #endif

 static int __init
 init_crypto_wep(void)
 {
 	ieee80211_crypto_register(&wep);
 	return 0;
 }
 module_init(init_crypto_wep);

 static void __exit
 exit_crypto_wep(void)
 {
 	ieee80211_crypto_unregister(&wep);
 }
 module_exit(exit_crypto_wep);
	/*-
	* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* Alternatively, this software may be distributed under the terms of the
	* GNU General Public License ("GPL") version 2 as published by the Free
	* Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* $Id: ieee80211_crypto_wep.c 1721 2006-09-20 08:45:13Z mentor $
	*/

	/*
	* IEEE 802.11 WEP crypto support.
	*/
	#ifndef AUTOCONF_INCLUDED
	#include <linux/config.h>
	#endif
	#include <linux/version.h>
	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <linux/netdevice.h>
	#include <linux/random.h>
	#include <linux/init.h>

	#include "net80211/if_media.h"

	#include "net80211/ieee80211_var.h"

	static void wep_attach(struct ieee80211vap , struct ieee80211_key *);
	static void wep_detach(struct ieee80211_key *);
	static int wep_setkey(struct ieee80211_key *);
	static int wep_encap(struct ieee80211_key , struct sk_buff , u_int8_t);
	static int wep_decap(struct ieee80211_key , struct sk_buff , int);
	static int wep_enmic(struct ieee80211_key , struct sk_buff , int);
	static int wep_demic(struct ieee80211_key , struct sk_buff , int);

	static const struct ieee80211_cipher wep = {
	.ic_name = "WEP",
	.ic_cipher = IEEE80211_CIPHER_WEP,
	.ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
	.ic_trailer = IEEE80211_WEP_CRCLEN,
	.ic_miclen = 0,
	.ic_attach = wep_attach,
	.ic_detach = wep_detach,
	.ic_setkey = wep_setkey,
	.ic_encap = wep_encap,
	.ic_decap = wep_decap,
	.ic_enmic = wep_enmic,
	.ic_demic = wep_demic,
	};

	static int wep_encrypt(struct ieee80211_key , struct sk_buff , int);
	static int wep_decrypt(struct ieee80211_key , struct sk_buff , int);

	struct wep_ctx {
	struct ieee80211vap wc_vap; / for diagnostics + statistics */
	struct ieee80211com wc_ic; / for diagnostics */
	u_int32_t wc_iv; /* initial vector for crypto */
	};

	static void *
	wep_attach(struct ieee80211vap vap, struct ieee80211_key k)
	{
	struct wep_ctx *ctx;

	_MOD_INC_USE(THIS_MODULE, return NULL);

	MALLOC(ctx, struct wep_ctx *, sizeof(struct wep_ctx),
	M_DEVBUF, M_NOWAIT \| M_ZERO);
	if (ctx == NULL) {
	vap->iv_stats.is_crypto_nomem++;
	_MOD_DEC_USE(THIS_MODULE);
	return NULL;
	}

	ctx->wc_vap = vap;
	ctx->wc_ic = vap->iv_ic;
	get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
	return ctx;
	}

	static void
	wep_detach(struct ieee80211_key *k)
	{
	struct wep_ctx *ctx = k->wk_private;

	FREE(ctx, M_DEVBUF);

	_MOD_DEC_USE(THIS_MODULE);
	}

	static int
	wep_setkey(struct ieee80211_key *k)
	{
	return k->wk_keylen >= 40 / NBBY;
	}

	#ifndef _BYTE_ORDER
	#error "Don't know native byte order"
	#endif

	/*
	* Add privacy headers appropriate for the specified key.
	*/
	static int
	wep_encap(struct ieee80211_key k, struct sk_buff skb, u_int8_t keyid)
	{
	struct wep_ctx *ctx = k->wk_private;
	struct ieee80211com *ic = ctx->wc_ic;
	u_int32_t iv;
	u_int8_t *ivp;
	int hdrlen;

	hdrlen = ieee80211_hdrspace(ic, skb->data);

	/*
	* Copy down 802.11 header and add the IV + KeyID.
	*/
	ivp = skb_push(skb, wep.ic_header);
	memmove(ivp, ivp + wep.ic_header, hdrlen);
	ivp += hdrlen;

	/*
	* XXX
	* IV must not duplicate during the lifetime of the key.
	* But no mechanism to renew keys is defined in IEEE 802.11
	* for WEP. And the IV may be duplicated at other stations
	* because the session key itself is shared. So we use a
	* pseudo random IV for now, though it is not the right way.
	*
	* NB: Rather than use a strictly random IV we select a
	* random one to start and then increment the value for
	* each frame. This is an explicit tradeoff between
	* overhead and security. Given the basic insecurity of
	* WEP this seems worthwhile.
	*/

	/*
	* Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
	* (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
	*/
	iv = ctx->wc_iv;
	if ((iv & 0xff00) == 0xff00) {
	int B = (iv & 0xff0000) >> 16;
	if (3 <= B && B < 16)
	iv += 0x0100;
	}
	ctx->wc_iv = iv + 1;

	/*
	* NB: Preserve byte order of IV for packet
	* sniffers; it doesn't matter otherwise.
	*/
	#if _BYTE_ORDER == _BIG_ENDIAN
	ivp[0] = iv >> 0;
	ivp[1] = iv >> 8;
	ivp[2] = iv >> 16;
	#else
	ivp[2] = iv >> 0;
	ivp[1] = iv >> 8;
	ivp[0] = iv >> 16;
	#endif
	ivp[3] = keyid;

	/*
	* Finally, do software encrypt if neeed.
	*/
	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
	!wep_encrypt(k, skb, hdrlen))
	return 0;

	return 1;
	}

	/*
	* Add MIC to the frame as needed.
	*/
	static int
	wep_enmic(struct ieee80211_key k, struct sk_buff skb, int force)
	{
	return 1;
	}

	/*
	* Validate and strip privacy headers (and trailer) for a
	* received frame. If necessary, decrypt the frame using
	* the specified key.
	*/
	static int
	wep_decap(struct ieee80211_key k, struct sk_buff skb, int hdrlen)
	{
	struct wep_ctx *ctx = k->wk_private;
	struct ieee80211vap *vap = ctx->wc_vap;
	struct ieee80211_frame *wh;

	wh = (struct ieee80211_frame *)skb->data;

	/*
	* Check if the device handled the decrypt in hardware.
	* If so we just strip the header; otherwise we need to
	* handle the decrypt in software.
	*/
	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
	!wep_decrypt(k, skb, hdrlen)) {
	IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
	"%s", "WEP ICV mismatch on decrypt");
	vap->iv_stats.is_rx_wepfail++;
	return 0;
	}

	/*
	* Copy up 802.11 header and strip crypto bits.
	*/
	memmove(skb->data + wep.ic_header, skb->data, hdrlen);
	skb_pull(skb, wep.ic_header);
	skb_trim(skb, skb->len - wep.ic_trailer);

	return 1;
	}

	/*
	* Verify and strip MIC from the frame.
	*/
	static int
	wep_demic(struct ieee80211_key k, struct sk_buff skb, int hdrlen)
	{
	return 1;
	}

	static const uint32_t crc32_table[256] = {
	0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
	0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
	0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
	0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
	0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
	0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
	0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
	0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
	0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
	0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
	0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
	0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
	0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
	0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
	0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
	0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
	0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
	0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
	0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
	0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
	0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
	0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
	0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
	0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
	0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
	0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
	0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
	0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
	0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
	0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
	0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
	0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
	0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
	0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
	0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
	0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
	0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
	0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
	0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
	0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
	0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
	0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
	0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
	0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
	0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
	0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
	0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
	0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
	0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
	0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
	0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
	0x2d02ef8dL
	};

	static int
	wep_encrypt(struct ieee80211_key key, struct sk_buff skb0, int hdrlen)
	{
	#define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
	struct wep_ctx *ctx = key->wk_private;
	struct ieee80211vap *vap = ctx->wc_vap;
	struct sk_buff *skb = skb0;
	u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
	uint8_t *icv;
	uint32_t i, j, k, crc;
	size_t buflen, data_len;
	uint8_t S[256];
	uint8_t *pos;
	u_int off, keylen;

	vap->iv_stats.is_crypto_wep++;

	/* NB: this assumes the header was pulled up */
	memcpy(rc4key, skb->data + hdrlen, IEEE80211_WEP_IVLEN);
	memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);

	/* Setup RC4 state */
	for (i = 0; i < 256; i++)
	S[i] = i;
	j = 0;
	keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
	for (i = 0; i < 256; i++) {
	j = (j + S[i] + rc4key[i % keylen]) & 0xff;
	S_SWAP(i, j);
	}

	off = hdrlen + wep.ic_header;
	data_len = skb->len - off;

	/* Compute CRC32 over unencrypted data and apply RC4 to data */
	crc = ~0;
	i = j = 0;
	pos = skb->data + off;
	buflen = skb->len - off;
	for (;;) {
	if (buflen > data_len)
	buflen = data_len;
	data_len -= buflen;
	for (k = 0; k < buflen; k++) {
	crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
	i = (i + 1) & 0xff;
	j = (j + S[i]) & 0xff;
	S_SWAP(i, j);
	*pos++ ^= S[(S[i] + S[j]) & 0xff];
	}
	if (skb->next == NULL) {
	if (data_len != 0) { /* out of data */
	#ifdef IEEE80211_DEBUG
	const struct ieee80211_frame *wh =
	(const struct ieee80211_frame *) skb0->data;
	#endif
	IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
	wh->i_addr2,
	"out of data for WEP (data_len %lu)",
	(unsigned long) data_len);
	return 0;
	}
	break;
	}
	skb = skb->next;
	pos = skb->data;
	buflen = skb->len;
	}
	crc = ~crc;

	if (skb_tailroom(skb) < wep.ic_trailer) {
	#ifdef IEEE80211_DEBUG
	const struct ieee80211_frame *wh =
	(const struct ieee80211_frame *) skb0->data;
	#endif
	/* NB: should not happen */
	IEEE80211_NOTE_MAC(ctx->wc_vap, IEEE80211_MSG_CRYPTO,
	wh->i_addr1, "no room for %s ICV, tailroom %u",
	wep.ic_name, skb_tailroom(skb));
	/* XXX statistic */
	return 0;
	}
	/* Append little-endian CRC32 and encrypt it to produce ICV */
	icv = skb_put(skb, IEEE80211_WEP_CRCLEN);
	icv[0] = crc;
	icv[1] = crc >> 8;
	icv[2] = crc >> 16;
	icv[3] = crc >> 24;
	for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
	i = (i + 1) & 0xff;
	j = (j + S[i]) & 0xff;
	S_SWAP(i, j);
	icv[k] ^= S[(S[i] + S[j]) & 0xff];
	}
	return 1;
	#undef S_SWAP
	}

	static int
	wep_decrypt(struct ieee80211_key key, struct sk_buff skb0, int hdrlen)
	{
	#define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
	struct wep_ctx *ctx = key->wk_private;
	struct ieee80211vap *vap = ctx->wc_vap;
	struct sk_buff *skb = skb0;
	u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
	uint8_t icv[IEEE80211_WEP_CRCLEN];
	uint32_t i, j, k, crc;
	size_t buflen, data_len;
	uint8_t S[256];
	uint8_t *pos;
	u_int off, keylen;

	vap->iv_stats.is_crypto_wep++;

	/* NB: this assumes the header was pulled up */
	memcpy(rc4key, skb->data + hdrlen, IEEE80211_WEP_IVLEN);
	memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);

	/* Setup RC4 state */
	for (i = 0; i < 256; i++)
	S[i] = i;
	j = 0;
	keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
	for (i = 0; i < 256; i++) {
	j = (j + S[i] + rc4key[i % keylen]) & 0xff;
	S_SWAP(i, j);
	}

	off = hdrlen + wep.ic_header;
	data_len = skb->len - (off + wep.ic_trailer),

	/* Compute CRC32 over unencrypted data and apply RC4 to data */
	crc = ~0;
	i = j = 0;
	pos = skb->data + off;
	buflen = skb->len - off;
	for (;;) {
	if (buflen > data_len)
	buflen = data_len;
	data_len -= buflen;
	for (k = 0; k < buflen; k++) {
	i = (i + 1) & 0xff;
	j = (j + S[i]) & 0xff;
	S_SWAP(i, j);
	*pos ^= S[(S[i] + S[j]) & 0xff];
	crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
	pos++;
	}
	skb = skb->next;
	if (skb == NULL) {
	if (data_len != 0) { /* out of data */
	#ifdef IEEE80211_DEBUG
	const struct ieee80211_frame *wh =
	(const struct ieee80211_frame *) skb0->data;
	#endif
	IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
	wh->i_addr2,
	"out of data for WEP (data_len %lu)",
	(unsigned long) data_len);
	return 0;
	}
	break;
	}
	pos = skb->data;
	buflen = skb->len;
	}
	crc = ~crc;

	/* Encrypt little-endian CRC32 and verify that it matches with
	* received ICV */
	icv[0] = crc;
	icv[1] = crc >> 8;
	icv[2] = crc >> 16;
	icv[3] = crc >> 24;
	for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
	i = (i + 1) & 0xff;
	j = (j + S[i]) & 0xff;
	S_SWAP(i, j);
	/* XXX assumes ICV is contiguous in sk_buf */
	if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
	/* ICV mismatch - drop frame */
	return 0;
	}
	}
	return 1;
	#undef S_SWAP
	}

	/*
	* Module glue.
	*/

	MODULE_AUTHOR("Errno Consulting, Sam Leffler");
	MODULE_DESCRIPTION("802.11 wireless support: WEP cipher");
	#ifdef MODULE_LICENSE
	MODULE_LICENSE("Dual BSD/GPL");
	#endif

	static int __init
	init_crypto_wep(void)
	{
	ieee80211_crypto_register(&wep);
	return 0;
	}
	module_init(init_crypto_wep);

	static void __exit
	exit_crypto_wep(void)
	{
	ieee80211_crypto_unregister(&wep);
	}
	module_exit(exit_crypto_wep);