madwifi/net80211/ieee80211_crypto.c

/*-
 * 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.
 *
 * $Id$
 */
#ifndef EXPORT_SYMTAB
#define	EXPORT_SYMTAB
#endif

/*
 * IEEE 802.11 generic crypto support.
 */
#ifndef AUTOCONF_INCLUDED
#include <linux/config.h>
#endif
#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"		/* for 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 ieee80211_keyix_t
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 ieee80211_keyix_t
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-zeroed */
	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 referenced */
	ciphers[cip->ic_cipher] = NULL;
}
EXPORT_SYMBOL(ieee80211_crypto_unregister);

/* 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    */
};


int
ieee80211_crypto_available(struct ieee80211vap *vap, u_int cipher)
{
#define	N(a)	(sizeof(a) / sizeof(a[0]))
	unsigned int status = 0;

	if (cipher < IEEE80211_CIPHER_MAX) {
		if (ciphers[cipher] == 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.
				 */
				if (ciphers[cipher] == 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++;
				} else
					status = 1;
			}
		} else
			status = 1;
	}
	return status;
#undef N
}
EXPORT_SYMBOL(ieee80211_crypto_available);

/*
 * 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)
{
	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)
		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))) {
		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;
	}
	/*
	 * Hardware TKIP with software MIC is an important
	 * combination; we handle it by flagging each key,
	 * the cipher modules honor it.
	 */
	if (cipher == IEEE80211_CIPHER_TKIP) {
		if (!(vap->iv_caps & IEEE80211_C_TKIPMIC)) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: no h/w support for TKIP MIC, falling back to s/w\n",
				__func__);
			flags |= IEEE80211_KEY_SWMIC;
	    	} else if (!((vap->iv_caps & IEEE80211_C_WME_TKIPMIC)) &&
		    (vap->iv_flags & IEEE80211_F_WME)) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: no h/w support for TKIP MIC when WMM is turned on,"
				" falling back to s/w\n",
				__func__);
			flags |= IEEE80211_KEY_SWMIC;
		}
	}

	/*
	 * Bind cipher to key instance.  Note we do this
	 * after checking the device capabilities so the
	 * cipher module can optimize space usage based on
	 * whether or not it needs to do the cipher work.
	 */
	if ((key->wk_cipher != cip) || (key->wk_flags != flags)) {
again:
		/*
		 * Fill in the flags so cipher modules can see s/w
		 * crypto requirements and potentially allocate
		 * different state and/or attach different method
		 * pointers.
		 *
		 * XXX: This is not right when s/w crypto fallback
		 *      fails and we try to restore previous state.
		 */
		key->wk_flags = flags;
		keyctx = cip->ic_attach(vap, key);
		if (keyctx == NULL) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: unable to attach cipher %s\n",
				__func__, cip->ic_name);
			key->wk_flags = oflags;	/* restore old flags */
			vap->iv_stats.is_crypto_attachfail++;
			return 0;
		}
		cipher_detach(key);
		key->wk_cipher = cip;		/* XXX: refcnt? */
		key->wk_private = keyctx;
	}
	/*
	 * Commit to requested usage so driver can see the flags.
	 */
	key->wk_flags = flags;

	/*
	 * Ask the driver for a key index if we don't have one.
	 * Note that entries in the global key table always have
	 * an index; this means it's safe to call this routine
	 * for these entries just to setup the reference to the
	 * cipher template.  Note also that when using software
	 * crypto we also call the driver to give us a key index.
	 */
	if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
		key->wk_keyix = dev_key_alloc(vap, key);
		if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
			/*
			 * Driver has no room; fallback to doing crypto
			 * in the host.  We change the flags and start the
			 * procedure over.  If we get back here then there's
			 * no hope and we bail.  Note that this can leave
			 * the key in a inconsistent state if the caller
			 * continues to use it.
			 */
			if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) {
				vap->iv_stats.is_crypto_swfallback++;
				IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
					"%s: no h/w resources for cipher %s, "
					"falling back to s/w\n",
					__func__, cip->ic_name);
				oflags = key->wk_flags;
				flags |= IEEE80211_KEY_SWCRYPT;
				if (cipher == IEEE80211_CIPHER_TKIP)
					flags |= IEEE80211_KEY_SWMIC;
				goto again;
			}
			vap->iv_stats.is_crypto_keyfail++;
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: unable to setup cipher %s\n",
				__func__, cip->ic_name);
			return 0;
		}
	}
	return 1;
}
EXPORT_SYMBOL(ieee80211_crypto_newkey);

/*
 * Remove the key (no locking, for internal use).
 */
static int
_ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key,
	struct ieee80211_node *ni)
{
	ieee80211_keyix_t keyix;

	KASSERT(key->wk_cipher != NULL, ("No cipher!"));

	IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
		"%s: %s keyix %u flags 0x%x tsc %llu len %u\n", __func__,
		key->wk_cipher->ic_name, key->wk_keyix, key->wk_flags,
		(unsigned long long)key->wk_keytsc, key->wk_keylen);

	keyix = key->wk_keyix;
	if (keyix != IEEE80211_KEYIX_NONE) {
		/* Remove hardware entry. */
		/* XXX: key cache */
		if (!dev_key_delete(vap, key, ni)) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
				"%s: driver did not delete key index %u\n",
				__func__, keyix);
			vap->iv_stats.is_crypto_delkey++;
			/* XXX: recovery? */
		}
	}
	cipher_detach(key);
	memset(key, 0, sizeof(*key));
	ieee80211_crypto_resetkey(vap, key, IEEE80211_KEYIX_NONE);
	return 1;
}

/*
 * Remove the specified key.
 */
int
ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key,
	struct ieee80211_node *ni)
{
	int status;

#ifdef ATH_SUPERG_COMP
	/* If valid node entry is present cleanup the compression state */
	if (ni)
		dev_comp_set(vap, ni, 0);
#endif
	ieee80211_key_update_begin(vap);
	status = _ieee80211_crypto_delkey(vap, key, ni);
	ieee80211_key_update_end(vap);

	return status;
}
EXPORT_SYMBOL(ieee80211_crypto_delkey);

/*
 * Clear the global key table.
 */
void
ieee80211_crypto_delglobalkeys(struct ieee80211vap *vap)
{
	int i;

	ieee80211_key_update_begin(vap);
	for (i = 0; i < IEEE80211_WEP_NKID; i++)
		(void) _ieee80211_crypto_delkey(vap, &vap->iv_nw_keys[i], NULL);
	ieee80211_key_update_end(vap);
}
EXPORT_SYMBOL(ieee80211_crypto_delglobalkeys);

/*
 * Set the contents of the specified key.
 *
 * Locking must be handled by the caller using:
 *	ieee80211_key_update_begin(vap);
 *	ieee80211_key_update_end(vap);
 */
int
ieee80211_crypto_setkey(struct ieee80211vap *vap, struct ieee80211_key *key,
	const u_int8_t macaddr[IEEE80211_ADDR_LEN],
	struct ieee80211_node *ni)
{
	const struct ieee80211_cipher *cip = key->wk_cipher;
	int ret;

	KASSERT(cip != NULL, ("No cipher!"));

	IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
		"%s: %s keyix %u flags 0x%x mac %s  tsc %llu len %u\n", __func__,
		cip->ic_name, key->wk_keyix, key->wk_flags,
		ether_sprintf(macaddr), (unsigned long long)key->wk_keytsc,
		key->wk_keylen);

	/*
	 * Give cipher a chance to validate key contents.
	 * XXX: Should happen before modifying state.
	 */
	if (!cip->ic_setkey(key)) {
		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
			"%s: cipher %s rejected key index %u len %u flags 0x%x\n",
			__func__, cip->ic_name, key->wk_keyix,
			key->wk_keylen, key->wk_flags);
		vap->iv_stats.is_crypto_setkey_cipher++;
		return 0;
	}
	if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
		/* NB: Nothing allocated, should not happen */
		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
			"%s: no key index; should not happen!\n", __func__);
		vap->iv_stats.is_crypto_setkey_nokey++;
		return 0;
	}
	ret = dev_key_set(vap, key, macaddr);
#ifdef ATH_SUPERG_COMP
	if (ret && ni) {
		/* Enable decompression only on receive key entries */
		if (key->wk_flags & IEEE80211_KEY_RECV)
			dev_comp_set(vap, ni, 1);
	}
#endif

	return ret;
}
EXPORT_SYMBOL(ieee80211_crypto_setkey);

/*
 * Add privacy headers appropriate for the specified key.
 */
struct ieee80211_key *
ieee80211_crypto_encap(struct ieee80211_node *ni, struct sk_buff *skb)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211_key *k;
	struct ieee80211_frame *wh;
	const struct ieee80211_cipher *cip;
	u_int8_t keyid;

	/*
	 * Multicast traffic always uses the multicast key.
	 * Otherwise if a unicast key is set we use that and
	 * it is always key index 0.  When no unicast key is
	 * set we fall back to the default transmit key.
	 */
	wh = (struct ieee80211_frame *)skb->data;
	if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
	    ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) {
		if (vap->iv_def_txkey == IEEE80211_KEYIX_NONE) {
			IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
				wh->i_addr1,
				"no default transmit key (%s) deftxkey %u",
				__func__, vap->iv_def_txkey);
			vap->iv_stats.is_tx_nodefkey++;
			return NULL;
		}
		keyid = vap->iv_def_txkey;
		k = &vap->iv_nw_keys[vap->iv_def_txkey];
	} else {
		keyid = 0;
		k = &ni->ni_ucastkey;
	}
	cip = k->wk_cipher;
	if (skb_headroom(skb) < cip->ic_header) {
		/*
		 * Should not happen; ieee80211_skbhdr_adjust should
		 * have allocated enough space for all headers.
		 */
		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr1,
			"%s: malformed packet for cipher %s; headroom %u",
			__func__, cip->ic_name, skb_headroom(skb));
		vap->iv_stats.is_tx_noheadroom++;
		return NULL;
	}
	return (cip->ic_encap(k, skb, keyid << 6) ? k : NULL);
}
EXPORT_SYMBOL(ieee80211_crypto_encap);

/*
 * Validate and strip privacy headers (and trailer) for a
 * received frame that has the Protected Frame bit set.
 */
struct ieee80211_key *
ieee80211_crypto_decap(struct ieee80211_node *ni, struct sk_buff *skb, int hdrlen)
{
#define	IEEE80211_WEP_HDRLEN	(IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
#define	IEEE80211_WEP_MINLEN \
	(sizeof(struct ieee80211_frame) + \
	IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211_key *k;
	struct ieee80211_frame *wh;
	const struct ieee80211_cipher *cip;
	const u_int8_t *ivp;
	u_int8_t keyid;

	/* NB: this minimum size data frame could be bigger */
	if (skb->len < IEEE80211_WEP_MINLEN) {
		IEEE80211_NOTE(vap, IEEE80211_MSG_ANY, ni,
			"%s: WEP data frame too short, len %u",
			__func__, skb->len);
		vap->iv_stats.is_rx_tooshort++;	/* XXX: unique stat? */
		return NULL;
	}
	/*
	 * Locate the key. If unicast and there is no unicast
	 * key then we fall back to the key id in the header.
	 * This assumes unicast keys are only configured when
	 * the key id in the header is meaningless (typically 0).
	 */
	wh = (struct ieee80211_frame *) skb->data;
	ivp = skb->data + hdrlen;
	keyid = ivp[IEEE80211_WEP_IVLEN];
	if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
	    ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none)
		k = &vap->iv_nw_keys[keyid >> 6];
	else
		k = &ni->ni_ucastkey;

	cip = k->wk_cipher;
	return (cip->ic_decap(k, skb, hdrlen) ? k : NULL);
#undef IEEE80211_WEP_MINLEN
#undef IEEE80211_WEP_HDRLEN
}
EXPORT_SYMBOL(ieee80211_crypto_decap);