[wpa] Add general support for WPA-protected 802.11 networks

Modified-by: Marty Connor <mdc@etherboot.org>
Signed-off-by: Marty Connor <mdc@etherboot.org>

src/include/gpxe/errfile.h

@@ -161,6 +161,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_sec80211		( ERRFILE_NET | 0x00230000 )
 #define ERRFILE_wep			( ERRFILE_NET | 0x00240000 )
 #define ERRFILE_eapol			( ERRFILE_NET | 0x00250000 )
+#define ERRFILE_wpa			( ERRFILE_NET | 0x00260000 )
 
 #define ERRFILE_image		      ( ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_elf		      ( ERRFILE_IMAGE | 0x00010000 )

src/include/gpxe/wpa.h

@@ -0,0 +1,503 @@
+/*
+ * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _GPXE_WPA_H
+#define _GPXE_WPA_H
+
+#include <gpxe/ieee80211.h>
+#include <gpxe/list.h>
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Common definitions for all types of WPA-protected networks.
+ */
+
+
+/** EAPOL-Key type field for modern 802.11i/RSN WPA packets */
+#define EAPOL_KEY_TYPE_RSN	2
+
+/** Old EAPOL-Key type field used by WPA1 hardware before 802.11i ratified */
+#define EAPOL_KEY_TYPE_WPA	254
+
+
+/**
+ * @defgroup eapol_key_info EAPOL-Key Info field bits
+ * @{
+ */
+
+/** Key descriptor version, indicating WPA or WPA2 */
+#define EAPOL_KEY_INFO_VERSION	0x0007
+
+/** Key type bit, indicating pairwise or group */
+#define EAPOL_KEY_INFO_TYPE	0x0008
+
+/** Key install bit; set on message 3 except when legacy hacks are used */
+#define EAPOL_KEY_INFO_INSTALL	0x0040
+
+/** Key ACK bit; set when a response is required, on all messages except #4 */
+#define EAPOL_KEY_INFO_KEY_ACK	0x0080
+
+/** Key MIC bit; set when the MIC field is valid, on messages 3 and 4 */
+#define EAPOL_KEY_INFO_KEY_MIC	0x0100
+
+/** Secure bit; set when both sides have both keys, on messages 3 and 4 */
+#define EAPOL_KEY_INFO_SECURE	0x0200
+
+/** Error bit; set on a MIC failure for TKIP */
+#define EAPOL_KEY_INFO_ERROR	0x0400
+
+/** Request bit; set when authentication is initiated by the Peer (unusual) */
+#define EAPOL_KEY_INFO_REQUEST	0x0800
+
+/** Key Encrypted bit; set when the Key Data field is encrypted */
+#define EAPOL_KEY_INFO_KEY_ENC	0x1000
+
+/** SMC Message bit; set when this frame is part of an IBSS SMK handshake */
+#define EAPOL_KEY_INFO_SMC_MESS	0x2000
+
+
+/** Key descriptor version field value for WPA (TKIP) */
+#define EAPOL_KEY_VERSION_WPA	1
+
+/** Key descriptor version field value for WPA2 (CCMP) */
+#define EAPOL_KEY_VERSION_WPA2	2
+
+/** Key type field value for a PTK (pairwise) key handshake */
+#define EAPOL_KEY_TYPE_PTK	0x0008
+
+/** Key type field value for a GTK (group) key handshake */
+#define EAPOL_KEY_TYPE_GTK	0x0000
+
+/** @} */
+
+
+
+/** An EAPOL-Key packet.
+ *
+ * These are used for the WPA 4-Way Handshake, whether or not prior
+ * authentication has been performed using EAP.
+ *
+ * On LANs, an eapol_key_pkt is always encapsulated in the data field
+ * of an eapol_frame, with the frame's type code set to EAPOL_TYPE_KEY.
+ *
+ * Unlike 802.11 frame headers, the fields in this structure are
+ * stored in big-endian!
+ */
+struct eapol_key_pkt
+{
+	/** One of the EAPOL_KEY_TYPE_* defines. */
+	u8 type;
+
+	/** Bitfield of key characteristics, network byte order */
+	u16 info;
+
+	/** Length of encryption key to be used, network byte order
+	 *
+	 * This is 16 for CCMP, 32 for TKIP, and 5 or 13 for WEP.
+	 */
+	u16 keysize;
+
+	/** Monotonically increasing value for EAPOL-Key conversations
+	 *
+	 * In another classic demonstration of overengineering, this
+	 * 8-byte value will rarely be anything above 1. It's stored
+	 * in network byte order.
+	 */
+	u64 replay;
+
+	/** Nonce value
+	 *
+	 * This is the authenticator's ANonce in frame 1, the peer's
+	 * SNonce in frame 2, and 0 in frames 3 and 4.
+	 */
+	u8 nonce[32];
+
+	/** Initialization vector
+	 *
+	 * This contains the IV used with the Key Encryption Key, or 0
+	 * if the key is unencrypted or encrypted using an algorithm
+	 * that does not require an IV.
+	 */
+	u8 iv[16];
+
+	/** Receive sequence counter for GTK
+	 *
+	 * This is used to synchronize the client's replay counter for
+	 * ordinary data packets. The first six bytes contain PN0
+	 * through PN5 for CCMP mode, or TSC0 through TSC5 for TKIP
+	 * mode. The last two bytes are zero.
+	 */
+	u8 rsc[8];
+
+	/** Reserved bytes */
+	u8 _reserved[8];
+
+	/** Message integrity code over the entire EAPOL frame
+	 *
+	 * This is calculated using HMAC-MD5 when the key descriptor
+	 * version field in @a info is 1, and HMAC-SHA1 ignoring the
+	 * last 4 bytes of the hash when the version field in @a info
+	 * is 2.
+	 */
+	u8 mic[16];
+
+	/** Length of the @a data field in bytes, network byte order */
+	u16 datalen;
+
+	/** Key data
+	 *
+	 * This is formatted as a series of 802.11 information
+	 * elements, with cryptographic data encapsulated using a
+	 * "vendor-specific IE" code and an IEEE-specified OUI.
+	 */
+	u8 data[0];
+} __attribute__ (( packed ));
+
+
+/** WPA handshaking state */
+enum wpa_state {
+	/** Waiting for PMK to be set */
+	WPA_WAITING = 0,
+
+	/** Ready for 4-Way Handshake */
+	WPA_READY,
+
+	/** Performing 4-Way Handshake */
+	WPA_WORKING,
+
+	/** 4-Way Handshake succeeded */
+	WPA_SUCCESS,
+
+	/** 4-Way Handshake failed */
+	WPA_FAILURE,
+};
+
+/** Bitfield indicating a selection of WPA transient keys */
+enum wpa_keymask {
+	/** Pairwise transient key */
+	WPA_PTK = 1,
+
+	/** Group transient key */
+	WPA_GTK = 2,
+};
+
+
+/** Length of a nonce */
+#define WPA_NONCE_LEN		32
+
+/** Length of a TKIP main key */
+#define WPA_TKIP_KEY_LEN	16
+
+/** Length of a TKIP MIC key */
+#define WPA_TKIP_MIC_KEY_LEN	8
+
+/** Length of a CCMP key */
+#define WPA_CCMP_KEY_LEN	16
+
+/** Length of an EAPOL Key Confirmation Key */
+#define WPA_KCK_LEN		16
+
+/** Length of an EAPOL Key Encryption Key */
+#define WPA_KEK_LEN		16
+
+/** Usual length of a Pairwise Master Key */
+#define WPA_PMK_LEN		32
+
+/** Length of a PMKID */
+#define WPA_PMKID_LEN		16
+
+
+/** Structure of the Temporal Key for TKIP encryption */
+struct tkip_tk
+{
+	/** Main key: input to TKIP Phase 1 and Phase 2 key mixing functions */
+	u8 key[WPA_TKIP_KEY_LEN];
+
+	/** Michael MIC keys */
+	struct {
+		/** MIC key for packets from the AP */
+		u8 rx[WPA_TKIP_MIC_KEY_LEN];
+
+		/** MIC key for packets to the AP */
+		u8 tx[WPA_TKIP_MIC_KEY_LEN];
+	} __attribute__ (( packed )) mic;
+} __attribute__ (( packed ));
+
+/** Structure of a generic Temporal Key */
+union wpa_tk
+{
+	/** CCMP key */
+	u8 ccmp[WPA_CCMP_KEY_LEN];
+
+	/** TKIP keys */
+	struct tkip_tk tkip;
+};
+
+/** Structure of the Pairwise Transient Key */
+struct wpa_ptk
+{
+	/** EAPOL-Key Key Confirmation Key (KCK) */
+	u8 kck[WPA_KCK_LEN];
+
+	/** EAPOL-Key Key Encryption Key (KEK) */
+	u8 kek[WPA_KEK_LEN];
+
+	/** Temporal key */
+	union wpa_tk tk;
+} __attribute__ (( packed ));
+
+/** Structure of the Group Transient Key */
+struct wpa_gtk
+{
+	/** Temporal key */
+	union wpa_tk tk;
+} __attribute__ (( packed ));
+
+
+/** Common context for WPA security handshaking
+ *
+ * Any implementor of a particular handshaking type (e.g. PSK or EAP)
+ * must include this structure at the very beginning of their private
+ * data context structure, to allow the EAPOL-Key handling code to
+ * work. When the preliminary authentication is done, it is necessary
+ * to call wpa_start(), passing the PMK (derived from PSK or EAP MSK)
+ * as an argument. The handshaker can use its @a step function to
+ * monitor @a state in this wpa_ctx structure for success or
+ * failure. On success, the keys will be available in @a ptk and @a
+ * gtk according to the state of the @a valid bitmask.
+ *
+ * After an initial success, the parent handshaker does not need to
+ * concern itself with rekeying; the WPA common code takes care of
+ * that.
+ */
+struct wpa_common_ctx
+{
+	/** 802.11 device we are authenticating for */
+	struct net80211_device *dev;
+
+	/** The Pairwise Master Key to use in handshaking
+	 *
+	 * This is set either by running the PBKDF2 algorithm on a
+	 * passphrase with the SSID as salt to generate a pre-shared
+	 * key, or by copying the first 32 bytes of the EAP Master
+	 * Session Key in 802.1X-served authentication.
+	 */
+	u8 pmk[WPA_PMK_LEN];
+
+	/** Length of the Pairwise Master Key
+	 *
+	 * This is always 32 except with one EAP method which only
+	 * gives 16 bytes.
+	 */
+	int pmk_len;
+
+	/** State of EAPOL-Key handshaking */
+	enum wpa_state state;
+
+	/** Replay counter for this association
+	 *
+	 * This stores the replay counter value for the most recent
+	 * packet we've accepted. It is initially initialised to ~0 to
+	 * show we'll accept anything.
+	 */
+	u64 replay;
+
+	/** Mask of valid keys after authentication success
+	 *
+	 * If the PTK is not valid, the GTK should be used for both
+	 * unicast and multicast decryption; if the GTK is not valid,
+	 * multicast packets cannot be decrypted.
+	 */
+	enum wpa_keymask valid;
+
+	/** The cipher to use for unicast RX and all TX */
+	enum net80211_crypto_alg crypt;
+
+	/** The cipher to use for broadcast and multicast RX */
+	enum net80211_crypto_alg gcrypt;
+
+	/** The Pairwise Transient Key derived from the handshake */
+	struct wpa_ptk ptk;
+
+	/** The Group Transient Key derived from the handshake */
+	struct wpa_gtk gtk;
+
+	/** Authenticator-provided nonce */
+	u8 Anonce[WPA_NONCE_LEN];
+
+	/** Supplicant-generated nonce (that's us) */
+	u8 Snonce[WPA_NONCE_LEN];
+
+	/** Whether we should refrain from generating another SNonce */
+	int have_Snonce;
+
+	/** Data in WPA or RSN IE from AP's beacon frame */
+	void *ap_rsn_ie;
+
+	/** Length of @a ap_rsn_ie */
+	int ap_rsn_ie_len;
+
+	/** Whether @a ap_rsn_ie is an RSN IE (as opposed to old WPA) */
+	int ap_rsn_is_rsn;
+
+	/** List entry */
+	struct list_head list;
+};
+
+
+/** WPA handshake key integrity and encryption handler
+ *
+ * Note that due to the structure of the 4-Way Handshake we never
+ * actually need to encrypt key data, only decrypt it.
+ */
+struct wpa_kie {
+	/** Value of version bits in EAPOL-Key info field for which to use
+	 *
+	 * This should be one of the @c EAPOL_KEY_VERSION_* constants.
+	 */
+	int version;
+
+	/** Calculate MIC over message
+	 *
+	 * @v kck	Key Confirmation Key, 16 bytes
+	 * @v msg	Message to calculate MIC over
+	 * @v len	Number of bytes to calculate MIC over
+	 * @ret mic	Calculated MIC, 16 bytes long
+	 *
+	 * The @a mic return may point within @a msg, so it must not
+	 * be filled until the calculation has been performed.
+	 */
+	void ( * mic ) ( const void *kck, const void *msg, size_t len,
+			 void *mic );
+
+	/** Decrypt key data
+	 *
+	 * @v kek	Key Encryption Key, 16 bytes
+	 * @v iv	Initialisation vector for encryption, 16 bytes
+	 * @v msg	Message to decrypt (Key Data field)
+	 * @v len	Length of message
+	 * @ret msg	Decrypted message in place of original
+	 * @ret len	Updated to reflect encrypted length
+	 * @ret rc	Return status code
+	 *
+	 * The decrypted message is written over the encrypted one.
+	 */
+	int ( * decrypt ) ( const void *kek, const void *iv, void *msg,
+			    u16 *len );
+};
+
+#define WPA_KIES	__table ( struct wpa_kie, "wpa_kies" )
+#define __wpa_kie	__table_entry ( WPA_KIES, 01 )
+
+
+
+/**
+ * @defgroup wpa_kde Key descriptor element types
+ * @{
+ */
+
+/** Payload structure of the GTK-encapsulating KDE
+ *
+ * This does not include the IE type, length, or OUI bytes, which are
+ * generic to all KDEs.
+ */
+struct wpa_kde_gtk_encap
+{
+	/** Key ID and TX bit */
+	u8 id;
+
+	/** Reserved byte */
+	u8 _rsvd;
+
+	/** Encapsulated group transient key */
+	struct wpa_gtk gtk;
+} __attribute__ (( packed ));
+
+/** Mask for Key ID in wpa_kde_gtk::id field */
+#define WPA_GTK_KID	0x03
+
+/** Mask for Tx bit in wpa_kde_gtk::id field */
+#define WPA_GTK_TXBIT	0x04
+
+
+/** KDE type for an encapsulated Group Transient Key (requires encryption) */
+#define WPA_KDE_GTK	_MKOUI ( 0x00, 0x0F, 0xAC, 0x01 )
+
+/** KDE type for a MAC address */
+#define WPA_KDE_MAC	_MKOUI ( 0x00, 0x0F, 0xAC, 0x03 )
+
+/** KDE type for a PMKID */
+#define WPA_KDE_PMKID	_MKOUI ( 0x00, 0x0F, 0xAC, 0x04 )
+
+/** KDE type for a nonce */
+#define WPA_KDE_NONCE	_MKOUI ( 0x00, 0x0F, 0xAC, 0x06 )
+
+/** KDE type for a lifetime value */
+#define WPA_KDE_LIFETIME _MKOUI ( 0x00, 0x0F, 0xAC, 0x07 )
+
+
+/** Any key descriptor element type
+ *
+ * KDEs follow the 802.11 information element format of a type byte
+ * (in this case "vendor-specific", with the requisite OUI+subtype
+ * after length) and a length byte whose value does not include the
+ * length of the type and length bytes.
+ */
+struct wpa_kde
+{
+	/** Information element type: always 0xDD (IEEE80211_IE_VENDOR) */
+	u8 ie_type;
+
+	/** Length, not including ie_type and length fields */
+	u8 len;
+
+	/** OUI + type byte */
+	u32 oui_type;
+
+	/** Payload data */
+	union {
+		/** For GTK-type KDEs, encapsulated GTK */
+		struct wpa_kde_gtk_encap gtk_encap;
+
+		/** For MAC-type KDEs, the MAC address */
+		u8 mac[ETH_ALEN];
+
+		/** For PMKID-type KDEs, the PMKID */
+		u8 pmkid[WPA_PMKID_LEN];
+
+		/** For Nonce-type KDEs, the nonce */
+		u8 nonce[WPA_NONCE_LEN];
+
+		/** For Lifetime-type KDEs, the lifetime in seconds
+		 *
+		 * This is in network byte order!
+		 */
+		u32 lifetime;
+	};
+} __attribute__ (( packed ));
+
+/** @} */
+
+int wpa_make_rsn_ie ( struct net80211_device *dev, union ieee80211_ie **ie );
+int wpa_start ( struct net80211_device *dev, struct wpa_common_ctx *ctx,
+		const void *pmk, size_t pmk_len );
+void wpa_stop ( struct net80211_device *dev );
+
+#endif /* _GPXE_WPA_H */

src/net/80211/wpa.c

@@ -0,0 +1,973 @@
+/*
+ * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <gpxe/net80211.h>
+#include <gpxe/sec80211.h>
+#include <gpxe/wpa.h>
+#include <gpxe/eapol.h>
+#include <gpxe/crypto.h>
+#include <gpxe/arc4.h>
+#include <gpxe/crc32.h>
+#include <gpxe/sha1.h>
+#include <gpxe/hmac.h>
+#include <gpxe/list.h>
+#include <gpxe/ethernet.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+/** @file
+ *
+ * Handler for the aspects of WPA handshaking that are independent of
+ * 802.1X/PSK or TKIP/CCMP; this mostly involves the 4-Way Handshake.
+ */
+
+/** List of WPA contexts in active use. */
+struct list_head wpa_contexts = LIST_HEAD_INIT ( wpa_contexts );
+
+
+/**
+ * Return an error code and deauthenticate
+ *
+ * @v ctx	WPA common context
+ * @v rc	Return status code
+ * @ret rc	The passed return status code
+ */
+static int wpa_fail ( struct wpa_common_ctx *ctx, int rc )
+{
+	net80211_deauthenticate ( ctx->dev, rc );
+	return rc;
+}
+
+
+/**
+ * Find a cryptosystem handler structure from a crypto ID
+ *
+ * @v crypt	Cryptosystem ID
+ * @ret crypto	Cryptosystem handler structure
+ *
+ * If support for @a crypt is not compiled in to gPXE, or if @a crypt
+ * is NET80211_CRYPT_UNKNOWN, returns @c NULL.
+ */
+static struct net80211_crypto *
+wpa_find_cryptosystem ( enum net80211_crypto_alg crypt )
+{
+	struct net80211_crypto *crypto;
+
+	for_each_table_entry ( crypto, NET80211_CRYPTOS ) {
+		if ( crypto->algorithm == crypt )
+			return crypto;
+	}
+
+	return NULL;
+}
+
+
+/**
+ * Find WPA key integrity and encryption handler from key version field
+ *
+ * @v ver	Version bits of EAPOL-Key info field
+ * @ret kie	Key integrity and encryption handler
+ */
+struct wpa_kie * wpa_find_kie ( int version )
+{
+	struct wpa_kie *kie;
+
+	for_each_table_entry ( kie, WPA_KIES ) {
+		if ( kie->version == version )
+			return kie;
+	}
+
+	return NULL;
+}
+
+
+/**
+ * Construct RSN or WPA information element
+ *
+ * @v dev	802.11 device
+ * @ret ie_ret	RSN or WPA information element
+ * @ret rc	Return status code
+ *
+ * This function allocates, fills, and returns a RSN or WPA
+ * information element suitable for including in an association
+ * request frame to the network identified by @c dev->associating.
+ * If it is impossible to construct an information element consistent
+ * with gPXE's capabilities that is compatible with that network, or
+ * if none should be sent because that network's beacon included no
+ * security information, returns an error indication and leaves
+ * @a ie_ret unchanged.
+ *
+ * The returned IE will be of the same type (RSN or WPA) as was
+ * included in the beacon for the network it is destined for.
+ */
+int wpa_make_rsn_ie ( struct net80211_device *dev, union ieee80211_ie **ie_ret )
+{
+	u8 *rsn, *rsn_end;
+	int is_rsn;
+	u32 group_cipher;
+	enum net80211_crypto_alg gcrypt;
+	int ie_len;
+	u8 *iep;
+	struct ieee80211_ie_rsn *ie;
+	struct ieee80211_frame *hdr;
+	struct ieee80211_beacon *beacon;
+
+	if ( ! dev->associating ) {
+		DBG ( "WPA: Can't make RSN IE for a non-associating device\n" );
+		return -EINVAL;
+	}
+
+	hdr = dev->associating->beacon->data;
+	beacon = ( struct ieee80211_beacon * ) hdr->data;
+	rsn = sec80211_find_rsn ( beacon->info_element,
+				  dev->associating->beacon->tail, &is_rsn,
+				  &rsn_end );
+	if ( ! rsn ) {
+		DBG ( "WPA: Can't make RSN IE when we didn't get one\n" );
+		return -EINVAL;
+	}
+
+	rsn += 2;		/* skip version */
+	group_cipher = *( u32 * ) rsn;
+	gcrypt = sec80211_rsn_get_net80211_crypt ( group_cipher );
+
+	if ( ! wpa_find_cryptosystem ( gcrypt ) ||
+	     ! wpa_find_cryptosystem ( dev->associating->crypto ) ) {
+		DBG ( "WPA: No support for (GC:%d, PC:%d)\n",
+		      gcrypt, dev->associating->crypto );
+		return -ENOTSUP;
+	}
+
+	/* Everything looks good - make our IE. */
+
+	/* WPA IEs need 4 more bytes for the OUI+type */
+	ie_len = ieee80211_rsn_size ( 1, 1, 0, is_rsn ) + ( 4 * ! is_rsn );
+	iep = malloc ( ie_len );
+	if ( ! iep )
+		return -ENOMEM;
+
+	*ie_ret = ( union ieee80211_ie * ) iep;
+
+	/* Store ID and length bytes. */
+	*iep++ = ( is_rsn ? IEEE80211_IE_RSN : IEEE80211_IE_VENDOR );
+	*iep++ = ie_len - 2;
+
+	/* Store OUI+type for WPA IEs. */
+	if ( ! is_rsn ) {
+		*( u32 * ) iep = IEEE80211_WPA_OUI_VEN;
+		iep += 4;
+	}
+
+	/* If this is a WPA IE, the id and len bytes in the
+	   ieee80211_ie_rsn structure will not be valid, but by doing
+	   the cast we can fill all the other fields much more
+	   readily. */
+
+	ie = ( struct ieee80211_ie_rsn * ) ( iep - 2 );
+	ie->version = IEEE80211_RSN_VERSION;
+	ie->group_cipher = group_cipher;
+	ie->pairwise_count = 1;
+	ie->pairwise_cipher[0] =
+		sec80211_rsn_get_crypto_desc ( dev->associating->crypto,
+					       is_rsn );
+	ie->akm_count = 1;
+	ie->akm_list[0] =
+		sec80211_rsn_get_akm_desc ( dev->associating->handshaking,
+					    is_rsn );
+	if ( is_rsn ) {
+		ie->rsn_capab = 0;
+		ie->pmkid_count = 0;
+	}
+
+	return 0;
+}
+
+
+/**
+ * Set up generic WPA support to handle 4-Way Handshake
+ *
+ * @v dev	802.11 device
+ * @v ctx	WPA common context
+ * @v pmk	Pairwise Master Key to use for session
+ * @v pmk_len	Length of PMK, almost always 32
+ * @ret rc	Return status code
+ */
+int wpa_start ( struct net80211_device *dev, struct wpa_common_ctx *ctx,
+		const void *pmk, size_t pmk_len )
+{
+	struct io_buffer *iob;
+	struct ieee80211_frame *hdr;
+	struct ieee80211_beacon *beacon;
+	u8 *ap_rsn_ie = NULL, *ap_rsn_ie_end;
+
+	if ( ! dev->rsn_ie || ! dev->associating )
+		return -EINVAL;
+
+	ctx->dev = dev;
+	memcpy ( ctx->pmk, pmk, ctx->pmk_len = pmk_len );
+	ctx->state = WPA_READY;
+	ctx->replay = ~0ULL;
+
+	iob = dev->associating->beacon;
+	hdr = iob->data;
+	beacon = ( struct ieee80211_beacon * ) hdr->data;
+	ap_rsn_ie = sec80211_find_rsn ( beacon->info_element, iob->tail,
+					&ctx->ap_rsn_is_rsn, &ap_rsn_ie_end );
+	if ( ap_rsn_ie ) {
+		ctx->ap_rsn_ie = malloc ( ap_rsn_ie_end - ap_rsn_ie );
+		if ( ! ctx->ap_rsn_ie )
+			return -ENOMEM;
+		memcpy ( ctx->ap_rsn_ie, ap_rsn_ie, ap_rsn_ie_end - ap_rsn_ie );
+		ctx->ap_rsn_ie_len = ap_rsn_ie_end - ap_rsn_ie;
+	} else {
+		return -ENOENT;
+	}
+
+	ctx->crypt = dev->associating->crypto;
+	ctx->gcrypt = NET80211_CRYPT_UNKNOWN;
+
+	list_add_tail ( &ctx->list, &wpa_contexts );
+	return 0;
+}
+
+
+/**
+ * Disable handling of received WPA handshake frames
+ *
+ * @v dev	802.11 device
+ */
+void wpa_stop ( struct net80211_device *dev )
+{
+	struct wpa_common_ctx *ctx, *tmp;
+
+	list_for_each_entry_safe ( ctx, tmp, &wpa_contexts, list ) {
+		if ( ctx->dev == dev ) {
+			free ( ctx->ap_rsn_ie );
+			ctx->ap_rsn_ie = NULL;
+			list_del ( &ctx->list );
+		}
+	}
+}
+
+
+/**
+ * Check PMKID consistency
+ *
+ * @v ctx	WPA common context
+ * @v pmkid	PMKID to check against (16 bytes long)
+ * @ret rc	Zero if they match, or a negative error code if not
+ */
+int wpa_check_pmkid ( struct wpa_common_ctx *ctx, const u8 *pmkid )
+{
+	u8 sha1_ctx[SHA1_CTX_SIZE];
+	u8 my_pmkid[SHA1_SIZE];
+	u8 pmk[ctx->pmk_len];
+	size_t pmk_len;
+	struct {
+		char name[8];
+		u8 aa[ETH_ALEN];
+		u8 spa[ETH_ALEN];
+	} __attribute__ (( packed )) pmkid_data;
+
+	memcpy ( pmk, ctx->pmk, ctx->pmk_len );
+	pmk_len = ctx->pmk_len;
+
+	memcpy ( pmkid_data.name, "PMK Name", 8 );
+	memcpy ( pmkid_data.aa, ctx->dev->bssid, ETH_ALEN );
+	memcpy ( pmkid_data.spa, ctx->dev->netdev->ll_addr, ETH_ALEN );
+
+	hmac_init ( &sha1_algorithm, sha1_ctx, pmk, &pmk_len );
+	hmac_update ( &sha1_algorithm, sha1_ctx, &pmkid_data,
+		      sizeof ( pmkid_data ) );
+	hmac_final ( &sha1_algorithm, sha1_ctx, pmk, &pmk_len, my_pmkid );
+
+	if ( memcmp ( my_pmkid, pmkid, WPA_PMKID_LEN ) != 0 )
+		return -EACCES;
+
+	return 0;
+}
+
+
+/**
+ * Derive pairwise transient key
+ *
+ * @v ctx	WPA common context
+ */
+static void wpa_derive_ptk ( struct wpa_common_ctx *ctx )
+{
+	struct {
+		u8 mac1[ETH_ALEN];
+		u8 mac2[ETH_ALEN];
+		u8 nonce1[WPA_NONCE_LEN];
+		u8 nonce2[WPA_NONCE_LEN];
+	} __attribute__ (( packed )) ptk_data;
+
+	/* The addresses and nonces are stored in numerical order (!) */
+
+	if ( memcmp ( ctx->dev->netdev->ll_addr, ctx->dev->bssid,
+		      ETH_ALEN ) < 0 ) {
+		memcpy ( ptk_data.mac1, ctx->dev->netdev->ll_addr, ETH_ALEN );
+		memcpy ( ptk_data.mac2, ctx->dev->bssid, ETH_ALEN );
+	} else {
+		memcpy ( ptk_data.mac1, ctx->dev->bssid, ETH_ALEN );
+		memcpy ( ptk_data.mac2, ctx->dev->netdev->ll_addr, ETH_ALEN );
+	}
+
+	if ( memcmp ( ctx->Anonce, ctx->Snonce, WPA_NONCE_LEN ) < 0 ) {
+		memcpy ( ptk_data.nonce1, ctx->Anonce, WPA_NONCE_LEN );
+		memcpy ( ptk_data.nonce2, ctx->Snonce, WPA_NONCE_LEN );
+	} else {
+		memcpy ( ptk_data.nonce1, ctx->Snonce, WPA_NONCE_LEN );
+		memcpy ( ptk_data.nonce2, ctx->Anonce, WPA_NONCE_LEN );
+	}
+
+	DBGC2 ( ctx, "WPA %p A1 %s, A2 %s\n", ctx, eth_ntoa ( ptk_data.mac1 ),
+	       eth_ntoa ( ptk_data.mac2 ) );
+	DBGC2 ( ctx, "WPA %p Nonce1, Nonce2:\n", ctx );
+	DBGC2_HD ( ctx, ptk_data.nonce1, WPA_NONCE_LEN );
+	DBGC2_HD ( ctx, ptk_data.nonce2, WPA_NONCE_LEN );
+
+	prf_sha1 ( ctx->pmk, ctx->pmk_len,
+		   "Pairwise key expansion",
+		   &ptk_data, sizeof ( ptk_data ),
+		   &ctx->ptk, sizeof ( ctx->ptk ) );
+
+	DBGC2 ( ctx, "WPA %p PTK:\n", ctx );
+	DBGC2_HD ( ctx, &ctx->ptk, sizeof ( ctx->ptk ) );
+}
+
+
+/**
+ * Install pairwise transient key
+ *
+ * @v ctx	WPA common context
+ * @v len	Key length (16 for CCMP, 32 for TKIP)
+ * @ret rc	Return status code
+ */
+static inline int wpa_install_ptk ( struct wpa_common_ctx *ctx, int len )
+{
+	DBGC ( ctx, "WPA %p: installing %d-byte pairwise transient key\n",
+	       ctx, len );
+	DBGC2_HD ( ctx, &ctx->ptk.tk, len );
+
+	return sec80211_install ( &ctx->dev->crypto, ctx->crypt,
+				  &ctx->ptk.tk, len, NULL );
+}
+
+/**
+ * Install group transient key
+ *
+ * @v ctx	WPA common context
+ * @v len	Key length (16 for CCMP, 32 for TKIP)
+ * @v rsc	Receive sequence counter field in EAPOL-Key packet
+ * @ret rc	Return status code
+ */
+static inline int wpa_install_gtk ( struct wpa_common_ctx *ctx, int len,
+				    const void *rsc )
+{
+	DBGC ( ctx, "WPA %p: installing %d-byte group transient key\n",
+	       ctx, len );
+	DBGC2_HD ( ctx, &ctx->gtk.tk, len );
+
+	return sec80211_install ( &ctx->dev->gcrypto, ctx->gcrypt,
+				  &ctx->gtk.tk, len, rsc );
+}
+
+/**
+ * Search for group transient key, and install it if found
+ *
+ * @v ctx	WPA common context
+ * @v ie	Pointer to first IE in key data field
+ * @v ie_end	Pointer to first byte not in key data field
+ * @v rsc	Receive sequence counter field in EAPOL-Key packet
+ * @ret rc	Return status code
+ */
+static int wpa_maybe_install_gtk ( struct wpa_common_ctx *ctx,
+				   union ieee80211_ie *ie, void *ie_end,
+				   const void *rsc )
+{
+	struct wpa_kde *kde;
+
+	if ( ! ieee80211_ie_bound ( ie, ie_end ) )
+		return -ENOENT;
+
+	while ( ie ) {
+		if ( ie->id == IEEE80211_IE_VENDOR &&
+		     ie->vendor.oui == WPA_KDE_GTK )
+			break;
+
+		ie = ieee80211_next_ie ( ie, ie_end );
+	}
+
+	if ( ! ie )
+		return -ENOENT;
+
+	if ( ie->len - 6u > sizeof ( ctx->gtk.tk ) ) {
+		DBGC ( ctx, "WPA %p: GTK KDE is too long (%d bytes, max %d)\n",
+		       ctx, ie->len - 4, sizeof ( ctx->gtk.tk ) );
+		return -EINVAL;
+	}
+
+	/* XXX We ignore key ID for now. */
+	kde = ( struct wpa_kde * ) ie;
+	memcpy ( &ctx->gtk.tk, &kde->gtk_encap.gtk, kde->len - 6 );
+
+	return wpa_install_gtk ( ctx, kde->len - 6, rsc );
+}
+
+
+/**
+ * Allocate I/O buffer for construction of outgoing EAPOL-Key frame
+ *
+ * @v kdlen	Maximum number of bytes in the Key Data field
+ * @ret iob	Newly allocated I/O buffer
+ *
+ * The returned buffer will have space reserved for the link-layer and
+ * EAPOL headers, and will have @c iob->tail pointing to the start of
+ * the Key Data field. Thus, it is necessary to use iob_put() in
+ * filling the Key Data.
+ */
+static struct io_buffer * wpa_alloc_frame ( int kdlen )
+{
+	struct io_buffer *ret = alloc_iob ( sizeof ( struct eapol_key_pkt ) +
+					    kdlen + EAPOL_HDR_LEN +
+					    MAX_LL_HEADER_LEN );
+	if ( ! ret )
+		return NULL;
+
+	iob_reserve ( ret, MAX_LL_HEADER_LEN + EAPOL_HDR_LEN );
+	memset ( iob_put ( ret, sizeof ( struct eapol_key_pkt ) ), 0,
+		 sizeof ( struct eapol_key_pkt ) );
+
+	return ret;
+}
+
+
+/**
+ * Send EAPOL-Key packet
+ *
+ * @v iob	I/O buffer, with sufficient headroom for headers
+ * @v dev	802.11 device
+ * @v kie	Key integrity and encryption handler
+ * @v is_rsn	If TRUE, handshake uses new RSN format
+ * @ret rc	Return status code
+ *
+ * If a KIE is specified, the MIC will be filled in before transmission.
+ */
+static int wpa_send_eapol ( struct io_buffer *iob, struct wpa_common_ctx *ctx,
+			    struct wpa_kie *kie )
+{
+	struct eapol_key_pkt *pkt = iob->data;
+	struct eapol_frame *eapol = iob_push ( iob, EAPOL_HDR_LEN );
+
+	pkt->info = htons ( pkt->info );
+	pkt->keysize = htons ( pkt->keysize );
+	pkt->datalen = htons ( pkt->datalen );
+	pkt->replay = cpu_to_be64 ( pkt->replay );
+	eapol->version = EAPOL_THIS_VERSION;
+	eapol->type = EAPOL_TYPE_KEY;
+	eapol->length = htons ( iob->tail - iob->data - sizeof ( *eapol ) );
+
+	memset ( pkt->mic, 0, sizeof ( pkt->mic ) );
+	if ( kie )
+		kie->mic ( &ctx->ptk.kck, eapol, EAPOL_HDR_LEN +
+			   sizeof ( *pkt ) + ntohs ( pkt->datalen ),
+			   pkt->mic );
+
+	return net_tx ( iob, ctx->dev->netdev, &eapol_protocol,
+			ctx->dev->bssid );
+}
+
+
+/**
+ * Send second frame in 4-Way Handshake
+ *
+ * @v ctx	WPA common context
+ * @v pkt	First frame, to which this is a reply
+ * @v is_rsn	If TRUE, handshake uses new RSN format
+ * @v kie	Key integrity and encryption handler
+ * @ret rc	Return status code
+ */
+static int wpa_send_2_of_4 ( struct wpa_common_ctx *ctx,
+			     struct eapol_key_pkt *pkt, int is_rsn,
+			     struct wpa_kie *kie )
+{
+	struct io_buffer *iob = wpa_alloc_frame ( ctx->dev->rsn_ie->len + 2 );
+	struct eapol_key_pkt *npkt;
+
+	if ( ! iob )
+		return -ENOMEM;
+
+	npkt = iob->data;
+	memcpy ( npkt, pkt, sizeof ( *pkt ) );
+	npkt->info &= ~EAPOL_KEY_INFO_KEY_ACK;
+	npkt->info |= EAPOL_KEY_INFO_KEY_MIC;
+	if ( is_rsn )
+		npkt->keysize = 0;
+	memcpy ( npkt->nonce, ctx->Snonce, sizeof ( npkt->nonce ) );
+	npkt->datalen = ctx->dev->rsn_ie->len + 2;
+	memcpy ( iob_put ( iob, npkt->datalen ), ctx->dev->rsn_ie,
+		 npkt->datalen );
+
+	DBGC ( ctx, "WPA %p: sending 2/4\n", ctx );
+
+	return wpa_send_eapol ( iob, ctx, kie );
+}
+
+
+/**
+ * Handle receipt of first frame in 4-Way Handshake
+ *
+ * @v ctx	WPA common context
+ * @v pkt	EAPOL-Key packet
+ * @v is_rsn	If TRUE, frame uses new RSN format
+ * @v kie	Key integrity and encryption handler
+ * @ret rc	Return status code
+ */
+static int wpa_handle_1_of_4 ( struct wpa_common_ctx *ctx,
+			       struct eapol_key_pkt *pkt, int is_rsn,
+			       struct wpa_kie *kie )
+{
+	int rc;
+
+	if ( ctx->state == WPA_WAITING )
+		return -EINVAL;
+
+	ctx->state = WPA_WORKING;
+	memcpy ( ctx->Anonce, pkt->nonce, sizeof ( ctx->Anonce ) );
+	if ( ! ctx->have_Snonce ) {
+		get_random_bytes ( ctx->Snonce, sizeof ( ctx->Snonce ) );
+		ctx->have_Snonce = 1;
+	}
+
+	if ( is_rsn && pkt->datalen ) {
+		union ieee80211_ie *ie = ( union ieee80211_ie * ) pkt->data;
+		void *ie_end = pkt->data + pkt->datalen;
+
+		if ( ! ieee80211_ie_bound ( ie, ie_end ) ) {
+			DBGC ( ctx, "WPA %p: malformed PMKID KDE\n", ctx );
+			return wpa_fail ( ctx, -EINVAL );
+		}
+
+		while ( ie ) {
+			if ( ie->id == IEEE80211_IE_VENDOR &&
+			     ie->vendor.oui == WPA_KDE_PMKID ) {
+				rc = wpa_check_pmkid ( ctx, ie->vendor.data );
+				if ( rc < 0 ) {
+					DBGC ( ctx, "WPA %p ALERT: PMKID "
+					       "mismatch in 1/4\n", ctx );
+					return wpa_fail ( ctx, rc );
+				}
+			}
+
+			ie = ieee80211_next_ie ( ie, ie_end );
+		}
+	}
+
+	DBGC ( ctx, "WPA %p: received 1/4, looks OK\n", ctx );
+
+	wpa_derive_ptk ( ctx );
+
+	return wpa_send_2_of_4 ( ctx, pkt, is_rsn, kie );
+}
+
+
+/**
+ * Send fourth frame in 4-Way Handshake, or second in Group Key Handshake
+ *
+ * @v ctx	WPA common context
+ * @v pkt	EAPOL-Key packet for frame to which we're replying
+ * @v is_rsn	If TRUE, frame uses new RSN format
+ * @v kie	Key integrity and encryption handler
+ * @ret rc	Return status code
+ */
+static int wpa_send_final ( struct wpa_common_ctx *ctx,
+			    struct eapol_key_pkt *pkt, int is_rsn,
+			    struct wpa_kie *kie )
+{
+	struct io_buffer *iob = wpa_alloc_frame ( 0 );
+	struct eapol_key_pkt *npkt;
+
+	if ( ! iob )
+		return -ENOMEM;
+
+	npkt = iob->data;
+	memcpy ( npkt, pkt, sizeof ( *pkt ) );
+	npkt->info &= ~( EAPOL_KEY_INFO_KEY_ACK | EAPOL_KEY_INFO_INSTALL |
+			 EAPOL_KEY_INFO_KEY_ENC );
+	if ( is_rsn )
+		npkt->keysize = 0;
+	memset ( npkt->nonce, 0, sizeof ( npkt->nonce ) );
+	memset ( npkt->iv, 0, sizeof ( npkt->iv ) );
+	npkt->datalen = 0;
+
+	if ( npkt->info & EAPOL_KEY_INFO_TYPE )
+		DBGC ( ctx, "WPA %p: sending 4/4\n", ctx );
+	else
+		DBGC ( ctx, "WPA %p: sending 2/2\n", ctx );
+
+	return wpa_send_eapol ( iob, ctx, kie );
+
+}
+
+
+/**
+ * Handle receipt of third frame in 4-Way Handshake
+ *
+ * @v ctx	WPA common context
+ * @v pkt	EAPOL-Key packet
+ * @v is_rsn	If TRUE, frame uses new RSN format
+ * @v kie	Key integrity and encryption handler
+ * @ret rc	Return status code
+ */
+static int wpa_handle_3_of_4 ( struct wpa_common_ctx *ctx,
+			       struct eapol_key_pkt *pkt, int is_rsn,
+			       struct wpa_kie *kie )
+{
+	int rc;
+	u8 *this_rsn, *this_rsn_end;
+	u8 *new_rsn, *new_rsn_end;
+	int this_is_rsn, new_is_rsn;
+
+	if ( ctx->state == WPA_WAITING )
+		return -EINVAL;
+
+	ctx->state = WPA_WORKING;
+
+	/* Check nonce */
+	if ( memcmp ( ctx->Anonce, pkt->nonce, WPA_NONCE_LEN ) != 0 ) {
+		DBGC ( ctx, "WPA %p ALERT: nonce mismatch in 3/4\n", ctx );
+		return wpa_fail ( ctx, -EACCES );
+	}
+
+	/* Check RSN IE */
+	this_rsn = sec80211_find_rsn ( ( union ieee80211_ie * ) pkt->data,
+				       pkt->data + pkt->datalen,
+				       &this_is_rsn, &this_rsn_end );
+	if ( this_rsn )
+		new_rsn = sec80211_find_rsn ( ( union ieee80211_ie * )
+					              this_rsn_end,
+					      pkt->data + pkt->datalen,
+					      &new_is_rsn, &new_rsn_end );
+	else
+		new_rsn = NULL;
+
+	if ( ! ctx->ap_rsn_ie || ! this_rsn ||
+	     ctx->ap_rsn_ie_len != ( this_rsn_end - this_rsn ) ||
+	     ctx->ap_rsn_is_rsn != this_is_rsn ||
+	     memcmp ( ctx->ap_rsn_ie, this_rsn, ctx->ap_rsn_ie_len ) != 0 ) {
+		DBGC ( ctx, "WPA %p ALERT: RSN mismatch in 3/4\n", ctx );
+		DBGC2 ( ctx, "WPA %p RSNs (in 3/4, in beacon):\n", ctx );
+		DBGC2_HD ( ctx, this_rsn, this_rsn_end - this_rsn );
+		DBGC2_HD ( ctx, ctx->ap_rsn_ie, ctx->ap_rsn_ie_len );
+		return wpa_fail ( ctx, -EACCES );
+	}
+
+	/* Don't switch if they just supplied both styles of IE
+	   simultaneously; we need two RSN IEs or two WPA IEs to
+	   switch ciphers. They'll be immediately consecutive because
+	   of ordering guarantees. */
+	if ( new_rsn && this_is_rsn == new_is_rsn ) {
+		struct net80211_wlan *assoc = ctx->dev->associating;
+		DBGC ( ctx, "WPA %p: accommodating bait-and-switch tactics\n",
+		       ctx );
+		DBGC2 ( ctx, "WPA %p RSNs (in 3/4+beacon, new in 3/4):\n",
+			ctx );
+		DBGC2_HD ( ctx, this_rsn, this_rsn_end - this_rsn );
+		DBGC2_HD ( ctx, new_rsn, new_rsn_end - new_rsn );
+
+		if ( ( rc = sec80211_detect_ie ( new_is_rsn, new_rsn,
+						 new_rsn_end,
+						 &assoc->handshaking,
+						 &assoc->crypto ) ) != 0 )
+			DBGC ( ctx, "WPA %p: bait-and-switch invalid, staying "
+			       "with original request\n", ctx );
+	} else {
+		new_rsn = this_rsn;
+		new_is_rsn = this_is_rsn;
+		new_rsn_end = this_rsn_end;
+	}
+
+	/* Grab group cryptosystem ID */
+	ctx->gcrypt = sec80211_rsn_get_net80211_crypt ( *( u32 * )
+							( new_rsn + 2 ) );
+
+	/* Check for a GTK, if info field is encrypted */
+	if ( pkt->info & EAPOL_KEY_INFO_KEY_ENC ) {
+		rc = wpa_maybe_install_gtk ( ctx,
+					     ( union ieee80211_ie * ) pkt->data,
+					     pkt->data + pkt->datalen,
+					     pkt->rsc );
+		if ( rc < 0 ) {
+			DBGC ( ctx, "WPA %p did not install GTK in 3/4: %s\n",
+			       ctx, strerror ( rc ) );
+			if ( rc != -ENOENT )
+				return wpa_fail ( ctx, rc );
+		}
+	}
+
+	DBGC ( ctx, "WPA %p: received 3/4, looks OK\n", ctx );
+
+	/* Send final message */
+	rc = wpa_send_final ( ctx, pkt, is_rsn, kie );
+	if ( rc < 0 )
+		return wpa_fail ( ctx, rc );
+
+	/* Install PTK */
+	rc = wpa_install_ptk ( ctx, pkt->keysize );
+	if ( rc < 0 ) {
+		DBGC ( ctx, "WPA %p failed to install PTK: %s\n", ctx,
+		       strerror ( rc ) );
+		return wpa_fail ( ctx, rc );
+	}
+
+	/* Mark us as needing a new Snonce if we rekey */
+	ctx->have_Snonce = 0;
+
+	/* Done! */
+	ctx->state = WPA_SUCCESS;
+	return 0;
+}
+
+
+/**
+ * Handle receipt of first frame in Group Key Handshake
+ *
+ * @v ctx	WPA common context
+ * @v pkt	EAPOL-Key packet
+ * @v is_rsn	If TRUE, frame uses new RSN format
+ * @v kie	Key integrity and encryption handler
+ * @ret rc	Return status code
+ */
+static int wpa_handle_1_of_2 ( struct wpa_common_ctx *ctx,
+			       struct eapol_key_pkt *pkt, int is_rsn,
+			       struct wpa_kie *kie )
+{
+	int rc;
+
+	/*
+	 * WPA and RSN do this completely differently.
+	 *
+	 * The idea of encoding the GTK (or PMKID, or various other
+	 * things) into a KDE that looks like an information element
+	 * is an RSN innovation; old WPA code never encapsulates
+	 * things like that. If it looks like an info element, it
+	 * really is (for the WPA IE check in frames 2/4 and 3/4). The
+	 * "key data encrypted" bit in the info field is also specific
+	 * to RSN.
+	 *
+	 * So from an old WPA host, 3/4 does not contain an
+	 * encapsulated GTK. The first frame of the GK handshake
+	 * contains it, encrypted, but without a KDE wrapper, and with
+	 * the key ID field (which gPXE doesn't use) shoved away in
+	 * the reserved bits in the info field, and the TxRx bit
+	 * stealing the Install bit's spot.
+	 */
+
+	if ( is_rsn && ( pkt->info & EAPOL_KEY_INFO_KEY_ENC ) ) {
+		rc = wpa_maybe_install_gtk ( ctx,
+					     ( union ieee80211_ie * ) pkt->data,
+					     pkt->data + pkt->datalen,
+					     pkt->rsc );
+		if ( rc < 0 ) {
+			DBGC ( ctx, "WPA %p: failed to install GTK in 1/2: "
+			       "%s\n", ctx, strerror ( rc ) );
+			return wpa_fail ( ctx, rc );
+		}
+	} else {
+		rc = kie->decrypt ( &ctx->ptk.kek, pkt->iv, pkt->data,
+				    &pkt->datalen );
+		if ( rc < 0 ) {
+			DBGC ( ctx, "WPA %p: failed to decrypt GTK: %s\n",
+			       ctx, strerror ( rc ) );
+			return rc; /* non-fatal */
+		}
+		if ( pkt->datalen > sizeof ( ctx->gtk.tk ) ) {
+			DBGC ( ctx, "WPA %p: too much GTK data (%d > %d)\n",
+			       ctx, pkt->datalen, sizeof ( ctx->gtk.tk ) );
+			return wpa_fail ( ctx, -EINVAL );
+		}
+
+		memcpy ( &ctx->gtk.tk, pkt->data, pkt->datalen );
+		wpa_install_gtk ( ctx, pkt->datalen, pkt->rsc );
+	}
+
+	DBGC ( ctx, "WPA %p: received 1/2, looks OK\n", ctx );
+
+	return wpa_send_final ( ctx, pkt, is_rsn, kie );
+}
+
+
+/**
+ * Handle receipt of EAPOL-Key frame for WPA
+ *
+ * @v iob	I/O buffer
+ * @v netdev	Network device
+ * @v ll_source	Source link-layer address
+ */
+static int eapol_key_rx ( struct io_buffer *iob, struct net_device *netdev,
+			  const void *ll_source )
+{
+	struct net80211_device *dev = net80211_get ( netdev );
+	struct eapol_key_pkt *pkt = iob->data;
+	int is_rsn, found_ctx;
+	struct wpa_common_ctx *ctx;
+	int rc = 0;
+	struct wpa_kie *kie;
+	u8 their_mic[16], our_mic[16];
+
+	if ( pkt->type != EAPOL_KEY_TYPE_WPA &&
+	     pkt->type != EAPOL_KEY_TYPE_RSN ) {
+		DBG ( "EAPOL-Key: packet not of 802.11 type\n" );
+		rc = -EINVAL;
+		goto drop;
+	}
+
+	is_rsn = ( pkt->type == EAPOL_KEY_TYPE_RSN );
+
+	if ( ! dev ) {
+		DBG ( "EAPOL-Key: packet not from 802.11\n" );
+		rc = -EINVAL;
+		goto drop;
+	}
+
+	if ( memcmp ( dev->bssid, ll_source, ETH_ALEN ) != 0 ) {
+		DBG ( "EAPOL-Key: packet not from associated AP\n" );
+		rc = -EINVAL;
+		goto drop;
+	}
+
+	if ( ! ( ntohs ( pkt->info ) & EAPOL_KEY_INFO_KEY_ACK ) ) {
+		DBG ( "EAPOL-Key: packet sent in wrong direction\n" );
+		rc = -EINVAL;
+		goto drop;
+	}
+
+	found_ctx = 0;
+	list_for_each_entry ( ctx, &wpa_contexts, list ) {
+		if ( ctx->dev == dev ) {
+			found_ctx = 1;
+			break;
+		}
+	}
+
+	if ( ! found_ctx ) {
+		DBG ( "EAPOL-Key: no WPA context to handle packet for %p\n",
+		      dev );
+		rc = -ENOENT;
+		goto drop;
+	}
+
+	if ( ( void * ) ( pkt + 1 ) + ntohs ( pkt->datalen ) > iob->tail ) {
+		DBGC ( ctx, "WPA %p: packet truncated (has %d extra bytes, "
+		       "states %d)\n", ctx, iob->tail - ( void * ) ( pkt + 1 ),
+		       ntohs ( pkt->datalen ) );
+		rc = -EINVAL;
+		goto drop;
+	}
+
+	/* Get a handle on key integrity/encryption handler */
+	kie = wpa_find_kie ( ntohs ( pkt->info ) & EAPOL_KEY_INFO_VERSION );
+	if ( ! kie ) {
+		DBGC ( ctx, "WPA %p: no support for packet version %d\n", ctx,
+		       ntohs ( pkt->info ) & EAPOL_KEY_INFO_VERSION );
+		rc = wpa_fail ( ctx, -ENOTSUP );
+		goto drop;
+	}
+
+	/* Check MIC */
+	if ( ntohs ( pkt->info ) & EAPOL_KEY_INFO_KEY_MIC ) {
+		memcpy ( their_mic, pkt->mic, sizeof ( pkt->mic ) );
+		memset ( pkt->mic, 0, sizeof ( pkt->mic ) );
+		kie->mic ( &ctx->ptk.kck, ( void * ) pkt - EAPOL_HDR_LEN,
+			   EAPOL_HDR_LEN + sizeof ( *pkt ) +
+			   ntohs ( pkt->datalen ), our_mic );
+		DBGC2 ( ctx, "WPA %p MIC comparison (theirs, ours):\n", ctx );
+		DBGC2_HD ( ctx, their_mic, 16 );
+		DBGC2_HD ( ctx, our_mic, 16 );
+		if ( memcmp ( their_mic, our_mic, sizeof ( pkt->mic ) ) != 0 ) {
+			DBGC ( ctx, "WPA %p: EAPOL MIC failure\n", ctx );
+			goto drop;
+		}
+	}
+
+	/* Fix byte order to local */
+	pkt->info = ntohs ( pkt->info );
+	pkt->keysize = ntohs ( pkt->keysize );
+	pkt->datalen = ntohs ( pkt->datalen );
+	pkt->replay = be64_to_cpu ( pkt->replay );
+
+	/* Check replay counter */
+	if ( ctx->replay != ~0ULL && ctx->replay >= pkt->replay ) {
+		DBGC ( ctx, "WPA %p ALERT: Replay detected! "
+		       "(%08x:%08x >= %08x:%08x)\n", ctx,
+		       ( u32 ) ( ctx->replay >> 32 ), ( u32 ) ctx->replay,
+		       ( u32 ) ( pkt->replay >> 32 ), ( u32 ) pkt->replay );
+		rc = 0;		/* ignore without error */
+		goto drop;
+	}
+	ctx->replay = pkt->replay;
+
+	/* Decrypt key data */
+	if ( pkt->info & EAPOL_KEY_INFO_KEY_ENC ) {
+		rc = kie->decrypt ( &ctx->ptk.kek, pkt->iv, pkt->data,
+				    &pkt->datalen );
+		if ( rc < 0 ) {
+			DBGC ( ctx, "WPA %p: failed to decrypt packet: %s\n",
+			       ctx, strerror ( rc ) );
+			goto drop;
+		}
+	}
+
+	/* Hand it off to appropriate handler */
+	switch ( pkt->info & ( EAPOL_KEY_INFO_TYPE |
+			       EAPOL_KEY_INFO_KEY_MIC ) ) {
+	case EAPOL_KEY_TYPE_PTK:
+		rc = wpa_handle_1_of_4 ( ctx, pkt, is_rsn, kie );
+		break;
+
+	case EAPOL_KEY_TYPE_PTK | EAPOL_KEY_INFO_KEY_MIC:
+		rc = wpa_handle_3_of_4 ( ctx, pkt, is_rsn, kie );
+		break;
+
+	case EAPOL_KEY_TYPE_GTK | EAPOL_KEY_INFO_KEY_MIC:
+		rc = wpa_handle_1_of_2 ( ctx, pkt, is_rsn, kie );
+		break;
+
+	default:
+		DBGC ( ctx, "WPA %p: Invalid combination of key flags %04x\n",
+		       ctx, pkt->info );
+		rc = -EINVAL;
+		break;
+	}
+
+ drop:
+	free_iob ( iob );
+	return rc;
+}
+
+struct eapol_handler eapol_key_handler __eapol_handler = {
+	.type = EAPOL_TYPE_KEY,
+	.rx = eapol_key_rx,
+};
+
+/* WPA always needs EAPOL in order to be useful */
+REQUIRE_OBJECT ( eapol );