key.c

/*
 * Copyright (c) 2009 Atheros Communications Inc.
 * Copyright (c) 2010 Bruno Randolf <br1@einfach.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <linux/export.h>
#include <asm/unaligned.h>
#include <net/mac80211.h>

#include "ath.h"
#include "reg.h"

#define REG_READ			(common->ops->read)
#define REG_WRITE(_ah, _reg, _val)	(common->ops->write)(_ah, _val, _reg)
#define ENABLE_REGWRITE_BUFFER(_ah)			\
	if (common->ops->enable_write_buffer)		\
		common->ops->enable_write_buffer((_ah));

#define REGWRITE_BUFFER_FLUSH(_ah)			\
	if (common->ops->write_flush)			\
		common->ops->write_flush((_ah));


#define IEEE80211_WEP_NKID      4       /* number of key ids */

/************************/
/* Key Cache Management */
/************************/

bool ath_hw_keyreset(struct ath_common *common, u16 entry)
{
	u32 keyType;
	void *ah = common->ah;

	if (entry >= common->keymax) {
		ath_err(common, "keyreset: keycache entry %u out of range\n",
			entry);
		return false;
	}

	keyType = REG_READ(ah, AR_KEYTABLE_TYPE(entry));

	ENABLE_REGWRITE_BUFFER(ah);

	REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_KEY2(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_KEY3(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_KEY4(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_TYPE(entry), AR_KEYTABLE_TYPE_CLR);
	REG_WRITE(ah, AR_KEYTABLE_MAC0(entry), 0);
	REG_WRITE(ah, AR_KEYTABLE_MAC1(entry), 0);

	if (keyType == AR_KEYTABLE_TYPE_TKIP) {
		u16 micentry = entry + 64;

		REG_WRITE(ah, AR_KEYTABLE_KEY0(micentry), 0);
		REG_WRITE(ah, AR_KEYTABLE_KEY1(micentry), 0);
		REG_WRITE(ah, AR_KEYTABLE_KEY2(micentry), 0);
		REG_WRITE(ah, AR_KEYTABLE_KEY3(micentry), 0);
		if (common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED) {
			REG_WRITE(ah, AR_KEYTABLE_KEY4(micentry), 0);
			REG_WRITE(ah, AR_KEYTABLE_TYPE(micentry),
				  AR_KEYTABLE_TYPE_CLR);
		}

	}

	REGWRITE_BUFFER_FLUSH(ah);

	return true;
}
EXPORT_SYMBOL(ath_hw_keyreset);

static bool ath_hw_keysetmac(struct ath_common *common,
			     u16 entry, const u8 *mac)
{
	u32 macHi, macLo;
	u32 unicast_flag = AR_KEYTABLE_VALID;
	void *ah = common->ah;

	if (entry >= common->keymax) {
		ath_err(common, "keysetmac: keycache entry %u out of range\n",
			entry);
		return false;
	}

	if (mac != NULL) {
		/*
		 * AR_KEYTABLE_VALID indicates that the address is a unicast
		 * address, which must match the transmitter address for
		 * decrypting frames.
		 * Not setting this bit allows the hardware to use the key
		 * for multicast frame decryption.
		 */
		if (mac[0] & 0x01)
			unicast_flag = 0;

		macLo = get_unaligned_le32(mac);
		macHi = get_unaligned_le16(mac + 4);
		macLo >>= 1;
		macLo |= (macHi & 1) << 31;
		macHi >>= 1;
	} else {
		macLo = macHi = 0;
	}
	ENABLE_REGWRITE_BUFFER(ah);

	REG_WRITE(ah, AR_KEYTABLE_MAC0(entry), macLo);
	REG_WRITE(ah, AR_KEYTABLE_MAC1(entry), macHi | unicast_flag);

	REGWRITE_BUFFER_FLUSH(ah);

	return true;
}

static bool ath_hw_set_keycache_entry(struct ath_common *common, u16 entry,
				      const struct ath_keyval *k,
				      const u8 *mac)
{
	void *ah = common->ah;
	u32 key0, key1, key2, key3, key4;
	u32 keyType;

	if (entry >= common->keymax) {
		ath_err(common, "set-entry: keycache entry %u out of range\n",
			entry);
		return false;
	}

	switch (k->kv_type) {
	case ATH_CIPHER_AES_OCB:
		keyType = AR_KEYTABLE_TYPE_AES;
		break;
	case ATH_CIPHER_AES_CCM:
		if (!(common->crypt_caps & ATH_CRYPT_CAP_CIPHER_AESCCM)) {
			ath_dbg(common, ANY,
				"AES-CCM not supported by this mac rev\n");
			return false;
		}
		keyType = AR_KEYTABLE_TYPE_CCM;
		break;
	case ATH_CIPHER_TKIP:
		keyType = AR_KEYTABLE_TYPE_TKIP;
		if (entry + 64 >= common->keymax) {
			ath_dbg(common, ANY,
				"entry %u inappropriate for TKIP\n", entry);
			return false;
		}
		break;
	case ATH_CIPHER_WEP:
		if (k->kv_len < WLAN_KEY_LEN_WEP40) {
			ath_dbg(common, ANY, "WEP key length %u too small\n",
				k->kv_len);
			return false;
		}
		if (k->kv_len <= WLAN_KEY_LEN_WEP40)
			keyType = AR_KEYTABLE_TYPE_40;
		else if (k->kv_len <= WLAN_KEY_LEN_WEP104)
			keyType = AR_KEYTABLE_TYPE_104;
		else
			keyType = AR_KEYTABLE_TYPE_128;
		break;
	case ATH_CIPHER_CLR:
		keyType = AR_KEYTABLE_TYPE_CLR;
		break;
	default:
		ath_err(common, "cipher %u not supported\n", k->kv_type);
		return false;
	}

	key0 = get_unaligned_le32(k->kv_val + 0);
	key1 = get_unaligned_le16(k->kv_val + 4);
	key2 = get_unaligned_le32(k->kv_val + 6);
	key3 = get_unaligned_le16(k->kv_val + 10);
	key4 = get_unaligned_le32(k->kv_val + 12);
	if (k->kv_len <= WLAN_KEY_LEN_WEP104)
		key4 &= 0xff;

	/*
	 * Note: Key cache registers access special memory area that requires
	 * two 32-bit writes to actually update the values in the internal
	 * memory. Consequently, the exact order and pairs used here must be
	 * maintained.
	 */

	if (keyType == AR_KEYTABLE_TYPE_TKIP) {
		u16 micentry = entry + 64;

		/*
		 * Write inverted key[47:0] first to avoid Michael MIC errors
		 * on frames that could be sent or received at the same time.
		 * The correct key will be written in the end once everything
		 * else is ready.
		 */
		REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), ~key0);
		REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), ~key1);

		/* Write key[95:48] */
		REG_WRITE(ah, AR_KEYTABLE_KEY2(entry), key2);
		REG_WRITE(ah, AR_KEYTABLE_KEY3(entry), key3);

		/* Write key[127:96] and key type */
		REG_WRITE(ah, AR_KEYTABLE_KEY4(entry), key4);
		REG_WRITE(ah, AR_KEYTABLE_TYPE(entry), keyType);

		/* Write MAC address for the entry */
		(void) ath_hw_keysetmac(common, entry, mac);

		if (common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED) {
			/*
			 * TKIP uses two key cache entries:
			 * Michael MIC TX/RX keys in the same key cache entry
			 * (idx = main index + 64):
			 * key0 [31:0] = RX key [31:0]
			 * key1 [15:0] = TX key [31:16]
			 * key1 [31:16] = reserved
			 * key2 [31:0] = RX key [63:32]
			 * key3 [15:0] = TX key [15:0]
			 * key3 [31:16] = reserved
			 * key4 [31:0] = TX key [63:32]
			 */
			u32 mic0, mic1, mic2, mic3, mic4;

			mic0 = get_unaligned_le32(k->kv_mic + 0);
			mic2 = get_unaligned_le32(k->kv_mic + 4);
			mic1 = get_unaligned_le16(k->kv_txmic + 2) & 0xffff;
			mic3 = get_unaligned_le16(k->kv_txmic + 0) & 0xffff;
			mic4 = get_unaligned_le32(k->kv_txmic + 4);

			ENABLE_REGWRITE_BUFFER(ah);

			/* Write RX[31:0] and TX[31:16] */
			REG_WRITE(ah, AR_KEYTABLE_KEY0(micentry), mic0);
			REG_WRITE(ah, AR_KEYTABLE_KEY1(micentry), mic1);

			/* Write RX[63:32] and TX[15:0] */
			REG_WRITE(ah, AR_KEYTABLE_KEY2(micentry), mic2);
			REG_WRITE(ah, AR_KEYTABLE_KEY3(micentry), mic3);

			/* Write TX[63:32] and keyType(reserved) */
			REG_WRITE(ah, AR_KEYTABLE_KEY4(micentry), mic4);
			REG_WRITE(ah, AR_KEYTABLE_TYPE(micentry),
				  AR_KEYTABLE_TYPE_CLR);

			REGWRITE_BUFFER_FLUSH(ah);

		} else {
			/*
			 * TKIP uses four key cache entries (two for group
			 * keys):
			 * Michael MIC TX/RX keys are in different key cache
			 * entries (idx = main index + 64 for TX and
			 * main index + 32 + 96 for RX):
			 * key0 [31:0] = TX/RX MIC key [31:0]
			 * key1 [31:0] = reserved
			 * key2 [31:0] = TX/RX MIC key [63:32]
			 * key3 [31:0] = reserved
			 * key4 [31:0] = reserved
			 *
			 * Upper layer code will call this function separately
			 * for TX and RX keys when these registers offsets are
			 * used.
			 */
			u32 mic0, mic2;

			mic0 = get_unaligned_le32(k->kv_mic + 0);
			mic2 = get_unaligned_le32(k->kv_mic + 4);

			ENABLE_REGWRITE_BUFFER(ah);

			/* Write MIC key[31:0] */
			REG_WRITE(ah, AR_KEYTABLE_KEY0(micentry), mic0);
			REG_WRITE(ah, AR_KEYTABLE_KEY1(micentry), 0);

			/* Write MIC key[63:32] */
			REG_WRITE(ah, AR_KEYTABLE_KEY2(micentry), mic2);
			REG_WRITE(ah, AR_KEYTABLE_KEY3(micentry), 0);

			/* Write TX[63:32] and keyType(reserved) */
			REG_WRITE(ah, AR_KEYTABLE_KEY4(micentry), 0);
			REG_WRITE(ah, AR_KEYTABLE_TYPE(micentry),
				  AR_KEYTABLE_TYPE_CLR);

			REGWRITE_BUFFER_FLUSH(ah);
		}

		ENABLE_REGWRITE_BUFFER(ah);

		/* MAC address registers are reserved for the MIC entry */
		REG_WRITE(ah, AR_KEYTABLE_MAC0(micentry), 0);
		REG_WRITE(ah, AR_KEYTABLE_MAC1(micentry), 0);

		/*
		 * Write the correct (un-inverted) key[47:0] last to enable
		 * TKIP now that all other registers are set with correct
		 * values.
		 */
		REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), key0);
		REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), key1);

		REGWRITE_BUFFER_FLUSH(ah);
	} else {
		ENABLE_REGWRITE_BUFFER(ah);

		/* Write key[47:0] */
		REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), key0);
		REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), key1);

		/* Write key[95:48] */
		REG_WRITE(ah, AR_KEYTABLE_KEY2(entry), key2);
		REG_WRITE(ah, AR_KEYTABLE_KEY3(entry), key3);

		/* Write key[127:96] and key type */
		REG_WRITE(ah, AR_KEYTABLE_KEY4(entry), key4);
		REG_WRITE(ah, AR_KEYTABLE_TYPE(entry), keyType);

		REGWRITE_BUFFER_FLUSH(ah);

		/* Write MAC address for the entry */
		(void) ath_hw_keysetmac(common, entry, mac);
	}

	return true;
}

static int ath_setkey_tkip(struct ath_common *common, u16 keyix, const u8 *key,
			   struct ath_keyval *hk, const u8 *addr,
			   bool authenticator)
{
	const u8 *key_rxmic;
	const u8 *key_txmic;

	key_txmic = key + NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
	key_rxmic = key + NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;

	if (addr == NULL) {
		/*
		 * Group key installation - only two key cache entries are used
		 * regardless of splitmic capability since group key is only
		 * used either for TX or RX.
		 */
		if (authenticator) {
			memcpy(hk->kv_mic, key_txmic, sizeof(hk->kv_mic));
			memcpy(hk->kv_txmic, key_txmic, sizeof(hk->kv_mic));
		} else {
			memcpy(hk->kv_mic, key_rxmic, sizeof(hk->kv_mic));
			memcpy(hk->kv_txmic, key_rxmic, sizeof(hk->kv_mic));
		}
		return ath_hw_set_keycache_entry(common, keyix, hk, addr);
	}
	if (common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED) {
		/* TX and RX keys share the same key cache entry. */
		memcpy(hk->kv_mic, key_rxmic, sizeof(hk->kv_mic));
		memcpy(hk->kv_txmic, key_txmic, sizeof(hk->kv_txmic));
		return ath_hw_set_keycache_entry(common, keyix, hk, addr);
	}

	/* Separate key cache entries for TX and RX */

	/* TX key goes at first index, RX key at +32. */
	memcpy(hk->kv_mic, key_txmic, sizeof(hk->kv_mic));
	if (!ath_hw_set_keycache_entry(common, keyix, hk, NULL)) {
		/* TX MIC entry failed. No need to proceed further */
		ath_err(common, "Setting TX MIC Key Failed\n");
		return 0;
	}

	memcpy(hk->kv_mic, key_rxmic, sizeof(hk->kv_mic));
	/* XXX delete tx key on failure? */
	return ath_hw_set_keycache_entry(common, keyix + 32, hk, addr);
}

static int ath_reserve_key_cache_slot_tkip(struct ath_common *common)
{
	int i;

	for (i = IEEE80211_WEP_NKID; i < common->keymax / 2; i++) {
		if (test_bit(i, common->keymap) ||
		    test_bit(i + 64, common->keymap))
			continue; /* At least one part of TKIP key allocated */
		if (!(common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED) &&
		    (test_bit(i + 32, common->keymap) ||
		     test_bit(i + 64 + 32, common->keymap)))
			continue; /* At least one part of TKIP key allocated */

		/* Found a free slot for a TKIP key */
		return i;
	}
	return -1;
}

static int ath_reserve_key_cache_slot(struct ath_common *common,
				      u32 cipher)
{
	int i;

	if (cipher == WLAN_CIPHER_SUITE_TKIP)
		return ath_reserve_key_cache_slot_tkip(common);

	/* First, try to find slots that would not be available for TKIP. */
	if (!(common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED)) {
		for (i = IEEE80211_WEP_NKID; i < common->keymax / 4; i++) {
			if (!test_bit(i, common->keymap) &&
			    (test_bit(i + 32, common->keymap) ||
			     test_bit(i + 64, common->keymap) ||
			     test_bit(i + 64 + 32, common->keymap)))
				return i;
			if (!test_bit(i + 32, common->keymap) &&
			    (test_bit(i, common->keymap) ||
			     test_bit(i + 64, common->keymap) ||
			     test_bit(i + 64 + 32, common->keymap)))
				return i + 32;
			if (!test_bit(i + 64, common->keymap) &&
			    (test_bit(i , common->keymap) ||
			     test_bit(i + 32, common->keymap) ||
			     test_bit(i + 64 + 32, common->keymap)))
				return i + 64;
			if (!test_bit(i + 64 + 32, common->keymap) &&
			    (test_bit(i, common->keymap) ||
			     test_bit(i + 32, common->keymap) ||
			     test_bit(i + 64, common->keymap)))
				return i + 64 + 32;
		}
	} else {
		for (i = IEEE80211_WEP_NKID; i < common->keymax / 2; i++) {
			if (!test_bit(i, common->keymap) &&
			    test_bit(i + 64, common->keymap))
				return i;
			if (test_bit(i, common->keymap) &&
			    !test_bit(i + 64, common->keymap))
				return i + 64;
		}
	}

	/* No partially used TKIP slots, pick any available slot */
	for (i = IEEE80211_WEP_NKID; i < common->keymax; i++) {
		/* Do not allow slots that could be needed for TKIP group keys
		 * to be used. This limitation could be removed if we know that
		 * TKIP will not be used. */
		if (i >= 64 && i < 64 + IEEE80211_WEP_NKID)
			continue;
		if (!(common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED)) {
			if (i >= 32 && i < 32 + IEEE80211_WEP_NKID)
				continue;
			if (i >= 64 + 32 && i < 64 + 32 + IEEE80211_WEP_NKID)
				continue;
		}

		if (!test_bit(i, common->keymap))
			return i; /* Found a free slot for a key */
	}

	/* No free slot found */
	return -1;
}

/*
 * Configure encryption in the HW.
 */
int ath_key_config(struct ath_common *common,
			  struct ieee80211_vif *vif,
			  struct ieee80211_sta *sta,
			  struct ieee80211_key_conf *key)
{
	struct ath_keyval hk;
	const u8 *mac = NULL;
	u8 gmac[ETH_ALEN];
	int ret = 0;
	int idx;

	memset(&hk, 0, sizeof(hk));

	switch (key->cipher) {
	case 0:
		hk.kv_type = ATH_CIPHER_CLR;
		break;
	case WLAN_CIPHER_SUITE_WEP40:
	case WLAN_CIPHER_SUITE_WEP104:
		hk.kv_type = ATH_CIPHER_WEP;
		break;
	case WLAN_CIPHER_SUITE_TKIP:
		hk.kv_type = ATH_CIPHER_TKIP;
		break;
	case WLAN_CIPHER_SUITE_CCMP:
		hk.kv_type = ATH_CIPHER_AES_CCM;
		break;
	default:
		return -EOPNOTSUPP;
	}

	hk.kv_len = key->keylen;
	if (key->keylen)
		memcpy(hk.kv_val, key->key, key->keylen);

	if (!(key->flags & IEEE80211_KEY_FLAG_PAIRWISE)) {
		switch (vif->type) {
		case NL80211_IFTYPE_AP:
			memcpy(gmac, vif->addr, ETH_ALEN);
			gmac[0] |= 0x01;
			mac = gmac;
			idx = ath_reserve_key_cache_slot(common, key->cipher);
			break;
		case NL80211_IFTYPE_ADHOC:
			if (!sta) {
				idx = key->keyidx;
				break;
			}
			memcpy(gmac, sta->addr, ETH_ALEN);
			gmac[0] |= 0x01;
			mac = gmac;
			idx = ath_reserve_key_cache_slot(common, key->cipher);
			break;
		default:
			idx = key->keyidx;
			break;
		}
	} else if (key->keyidx) {
		if (WARN_ON(!sta))
			return -EOPNOTSUPP;
		mac = sta->addr;

		if (vif->type != NL80211_IFTYPE_AP) {
			/* Only keyidx 0 should be used with unicast key, but
			 * allow this for client mode for now. */
			idx = key->keyidx;
		} else
			return -EIO;
	} else {
		if (WARN_ON(!sta))
			return -EOPNOTSUPP;
		mac = sta->addr;

		idx = ath_reserve_key_cache_slot(common, key->cipher);
	}

	if (idx < 0)
		return -ENOSPC; /* no free key cache entries */

	if (key->cipher == WLAN_CIPHER_SUITE_TKIP)
		ret = ath_setkey_tkip(common, idx, key->key, &hk, mac,
				      vif->type == NL80211_IFTYPE_AP);
	else
		ret = ath_hw_set_keycache_entry(common, idx, &hk, mac);

	if (!ret)
		return -EIO;

	set_bit(idx, common->keymap);
	if (key->cipher == WLAN_CIPHER_SUITE_CCMP)
		set_bit(idx, common->ccmp_keymap);

	if (key->cipher == WLAN_CIPHER_SUITE_TKIP) {
		set_bit(idx + 64, common->keymap);
		set_bit(idx, common->tkip_keymap);
		set_bit(idx + 64, common->tkip_keymap);
		if (!(common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED)) {
			set_bit(idx + 32, common->keymap);
			set_bit(idx + 64 + 32, common->keymap);
			set_bit(idx + 32, common->tkip_keymap);
			set_bit(idx + 64 + 32, common->tkip_keymap);
		}
	}

	return idx;
}
EXPORT_SYMBOL(ath_key_config);

/*
 * Delete Key.
 */
void ath_key_delete(struct ath_common *common, struct ieee80211_key_conf *key)
{
	ath_hw_keyreset(common, key->hw_key_idx);
	if (key->hw_key_idx < IEEE80211_WEP_NKID)
		return;

	clear_bit(key->hw_key_idx, common->keymap);
	clear_bit(key->hw_key_idx, common->ccmp_keymap);
	if (key->cipher != WLAN_CIPHER_SUITE_TKIP)
		return;

	clear_bit(key->hw_key_idx + 64, common->keymap);

	clear_bit(key->hw_key_idx, common->tkip_keymap);
	clear_bit(key->hw_key_idx + 64, common->tkip_keymap);

	if (!(common->crypt_caps & ATH_CRYPT_CAP_MIC_COMBINED)) {
		ath_hw_keyreset(common, key->hw_key_idx + 32);
		clear_bit(key->hw_key_idx + 32, common->keymap);
		clear_bit(key->hw_key_idx + 64 + 32, common->keymap);

		clear_bit(key->hw_key_idx + 32, common->tkip_keymap);
		clear_bit(key->hw_key_idx + 64 + 32, common->tkip_keymap);
	}
}
EXPORT_SYMBOL(ath_key_delete);