ieee80211_crypto.c

Linux下wifi实现

/*-
 * Copyright (c) 2001 Atsushi Onoe
 * 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.c 1426 2006-02-01 20:07:11Z mrenzmann $
 */
#ifndef EXPORT_SYMTAB
#define	EXPORT_SYMTAB
#endif

/*
 * IEEE 802.11 generic crypto support.
 */
#include <linux/config.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/random.h>

#include "if_ethersubr.h"		/* XXX ETHER_HDR_LEN */
#include "if_media.h"

#include <net80211/ieee80211_var.h>

/*
 * Table of registered cipher modules.
 */
static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];

static int _ieee80211_crypto_delkey(struct ieee80211vap *,
	struct ieee80211_key *, struct ieee80211_node *);

/*
 * Default "null" key management routines.
 */
static int
null_key_alloc(struct ieee80211vap *vap, const struct ieee80211_key *k)
{
	return IEEE80211_KEYIX_NONE;
}
static int
null_key_delete(struct ieee80211vap *vap, const struct ieee80211_key *k,
	struct ieee80211_node *ni)
{
	return 1;
}
static int
null_key_set(struct ieee80211vap *vap, const struct ieee80211_key *k,
	const u_int8_t mac[IEEE80211_ADDR_LEN])
{
	return 1;
}
static void null_key_update(struct ieee80211vap *vap)
{
}

#ifdef ATH_SUPERG_COMP
static void
null_comp_set(struct ieee80211vap *vap, struct ieee80211_node *ni, 
	int en)
{
}
#endif

/*
 * Write-arounds for common operations.
 */
static __inline void
cipher_detach(struct ieee80211_key *key)
{
	key->wk_cipher->ic_detach(key);
}

static __inline void *
cipher_attach(struct ieee80211vap *vap, struct ieee80211_key *key)
{
	return key->wk_cipher->ic_attach(vap, key);
}

/* 
 * Wrappers for driver key management methods.
 */
static __inline int
dev_key_alloc(struct ieee80211vap *vap, const struct ieee80211_key *key)
{
	return vap->iv_key_alloc(vap, key);
}

static __inline int
dev_key_delete(struct ieee80211vap *vap,	const struct ieee80211_key *key,
	struct ieee80211_node *ni)
{
	return vap->iv_key_delete(vap, key, ni);
}

static __inline int
dev_key_set(struct ieee80211vap *vap, const struct ieee80211_key *key,
	const u_int8_t mac[IEEE80211_ADDR_LEN])
{
	return vap->iv_key_set(vap, key, mac);
}

#ifdef ATH_SUPERG_COMP
static __inline void
dev_comp_set(struct ieee80211vap *vap, struct ieee80211_node *ni, int en)
{
	return vap->iv_comp_set(vap, ni, en);
}
#endif

/*
 * Setup crypto support for a device/shared instance.
 */
void
ieee80211_crypto_attach(struct ieee80211com *ic)
{
	/* NB: we assume everything is pre-zero'd */
	ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none;
}
EXPORT_SYMBOL(ieee80211_crypto_attach);

/*
 * Teardown crypto support.
 */
void
ieee80211_crypto_detach(struct ieee80211com *ic)
{
}
EXPORT_SYMBOL(ieee80211_crypto_detach);

/*
 * Setup crypto support for a vap.
 */
void
ieee80211_crypto_vattach(struct ieee80211vap *vap)
{
	int i;

	/* NB: we assume everything is pre-zero'd */
	vap->iv_def_txkey = IEEE80211_KEYIX_NONE;
	for (i = 0; i < IEEE80211_WEP_NKID; i++)
		ieee80211_crypto_resetkey(vap, &vap->iv_nw_keys[i],
			IEEE80211_KEYIX_NONE);
	/*
	 * Initialize the driver key support routines to noop entries.
	 * This is useful especially for the cipher test modules.
	 */
	vap->iv_key_alloc = null_key_alloc;
	vap->iv_key_set = null_key_set;
	vap->iv_key_delete = null_key_delete;
	vap->iv_key_update_begin = null_key_update;
	vap->iv_key_update_end = null_key_update;
#ifdef ATH_SUPERG_COMP
	vap->iv_comp_set = null_comp_set;
#endif
}
EXPORT_SYMBOL(ieee80211_crypto_vattach);

/*
 * Teardown crypto support for a vap.
 */
void
ieee80211_crypto_vdetach(struct ieee80211vap *vap)
{
	ieee80211_crypto_delglobalkeys(vap);
}
EXPORT_SYMBOL(ieee80211_crypto_vdetach);

/*
 * Register a crypto cipher module.
 */
void
ieee80211_crypto_register(const struct ieee80211_cipher *cip)
{
	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
		printf("%s: cipher %s has an invalid cipher index %u\n",
			__func__, cip->ic_name, cip->ic_cipher);
		return;
	}
	if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
		printf("%s: cipher %s registered with a different template\n",
			__func__, cip->ic_name);
		return;
	}
	ciphers[cip->ic_cipher] = cip;
}
EXPORT_SYMBOL(ieee80211_crypto_register);

/*
 * Unregister a crypto cipher module.
 */
void
ieee80211_crypto_unregister(const struct ieee80211_cipher *cip)
{
	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
		printf("%s: cipher %s has an invalid cipher index %u\n",
			__func__, cip->ic_name, cip->ic_cipher);
		return;
	}
	if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
		printf("%s: cipher %s registered with a different template\n",
			__func__, cip->ic_name);
		return;
	}
	/* NB: don't complain about not being registered */
	/* XXX disallow if references */
	ciphers[cip->ic_cipher] = NULL;
}
EXPORT_SYMBOL(ieee80211_crypto_unregister);

int
ieee80211_crypto_available(u_int cipher)
{
	return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL;
}
EXPORT_SYMBOL(ieee80211_crypto_available);

/* XXX well-known names! */
static const char *cipher_modnames[] = {
	"wlan_wep",	/* IEEE80211_CIPHER_WEP */
	"wlan_tkip",	/* IEEE80211_CIPHER_TKIP */
	"wlan_aes_ocb",	/* IEEE80211_CIPHER_AES_OCB */
	"wlan_ccmp",	/* IEEE80211_CIPHER_AES_CCM */
	"wlan_ckip",	/* IEEE80211_CIPHER_CKIP */
};

/*
 * Establish a relationship between the specified key and cipher
 * and, if necessary, allocate a hardware index from the driver.
 * Note that when a fixed key index is required it must be specified
 * and we blindly assign it w/o consulting the driver (XXX).
 *
 * This must be the first call applied to a key; all the other key
 * routines assume wk_cipher is setup.
 *
 * Locking must be handled by the caller using:
 *	ieee80211_key_update_begin(vap);
 *	ieee80211_key_update_end(vap);
 */
int
ieee80211_crypto_newkey(struct ieee80211vap *vap,
	int cipher, int flags, struct ieee80211_key *key)
{
#define	N(a)	(sizeof(a) / sizeof(a[0]))
	const struct ieee80211_cipher *cip;
	void *keyctx;
	int oflags;

	/*
	 * Validate cipher and set reference to cipher routines.
	 */
	if (cipher >= IEEE80211_CIPHER_MAX) {
		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
			"%s: invalid cipher %u\n", __func__, cipher);
		vap->iv_stats.is_crypto_badcipher++;
		return 0;
	}
	cip = ciphers[cipher];
	if (cip == NULL) {
		/*
		 * Auto-load cipher module if we have a well-known name
		 * for it.  It might be better to use string names rather
		 * than numbers and craft a module name based on the cipher
		 * name; e.g. wlan_cipher_<cipher-name>.
		 */
		if (cipher < N(cipher_modnames)) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: unregistered cipher %u, load module %s\n",
				__func__, cipher, cipher_modnames[cipher]);
			ieee80211_load_module(cipher_modnames[cipher]);
			/*
			 * If cipher module loaded it should immediately
			 * call ieee80211_crypto_register which will fill
			 * in the entry in the ciphers array.
			 */
			cip = ciphers[cipher];
		}
		if (cip == NULL) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: unable to load cipher %u, module %s\n",
				__func__, cipher,
				cipher < N(cipher_modnames) ?
					cipher_modnames[cipher] : "<unknown>");
			vap->iv_stats.is_crypto_nocipher++;
			return 0;
		}
	}

	oflags = key->wk_flags;
	flags &= IEEE80211_KEY_COMMON;
	/*
	 * If the hardware does not support the cipher then
	 * fallback to a host-based implementation.
	 */
	if ((vap->iv_caps & (1<<cipher)) == 0) {
		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
		    "%s: no h/w support for cipher %s, falling back to s/w\n",
		    __func__, cip->ic_name);
		flags |= IEEE80211_KEY_SWCRYPT;
	}