mka: Extend CAK/CKN-from-EAP-MSK API to pass in MSK length

This can be used to allow 256-bit key hierarchy to be derived from
EAP-based authentication. For now, the MSK length is hardcoded to 128
bits, so the previous behavior is maintained.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/pae/ieee802_1x_kay.c

@@ -66,8 +66,8 @@ static struct mka_alg mka_alg_tbl[] = {
 
 		.icv_len = DEFAULT_ICV_LEN,
 
-		.cak_trfm = ieee802_1x_cak_128bits_aes_cmac,
-		.ckn_trfm = ieee802_1x_ckn_128bits_aes_cmac,
+		.cak_trfm = ieee802_1x_cak_aes_cmac,
+		.ckn_trfm = ieee802_1x_ckn_aes_cmac,
 		.kek_trfm = ieee802_1x_kek_aes_cmac,
 		.ick_trfm = ieee802_1x_ick_aes_cmac,
 		.icv_hash = ieee802_1x_icv_aes_cmac,

src/pae/ieee802_1x_kay_i.h

@@ -68,9 +68,10 @@ struct mka_alg {
 	u8 parameter[4];
 	size_t icv_len;
 
-	int (*cak_trfm)(const u8 *msk, const u8 *mac1, const u8 *mac2, u8 *cak);
-	int (*ckn_trfm)(const u8 *msk, const u8 *mac1, const u8 *mac2,
-			const u8 *sid, size_t sid_len, u8 *ckn);
+	int (*cak_trfm)(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			const u8 *mac2, u8 *cak, size_t cak_bytes);
+	int (*ckn_trfm)(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			const u8 *mac2, const u8 *sid, size_t sid_len, u8 *ckn);
 	int (*kek_trfm)(const u8 *cak, size_t cak_bytes,
 			const u8 *ckn, size_t ckn_len,
 			u8 *kek, size_t kek_bytes);

src/pae/ieee802_1x_key.c

@@ -82,33 +82,32 @@ static int aes_kdf(const u8 *kdk, size_t kdk_bits,
 }
 
 
-/********** AES-CMAC-128 **********/
 /**
- * ieee802_1x_cak_128bits_aes_cmac
+ * ieee802_1x_cak_aes_cmac
  *
  * IEEE Std 802.1X-2010, 6.2.2
  * CAK = KDF(Key, Label, mac1 | mac2, CAKlength)
  */
-int ieee802_1x_cak_128bits_aes_cmac(const u8 *msk, const u8 *mac1,
-				    const u8 *mac2, u8 *cak)
+int ieee802_1x_cak_aes_cmac(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			    const u8 *mac2, u8 *cak, size_t cak_bytes)
 {
 	u8 context[2 * ETH_ALEN];
 
 	joint_two_mac(mac1, mac2, context);
-	return aes_kdf(msk, 128, "IEEE8021 EAP CAK",
-		       context, sizeof(context) * 8, 128, cak);
+	return aes_kdf(msk, 8 * msk_bytes, "IEEE8021 EAP CAK",
+		       context, sizeof(context) * 8, 8 * cak_bytes, cak);
 }
 
 
 /**
- * ieee802_1x_ckn_128bits_aes_cmac
+ * ieee802_1x_ckn_aes_cmac
  *
  * IEEE Std 802.1X-2010, 6.2.2
  * CKN = KDF(Key, Label, ID | mac1 | mac2, CKNlength)
  */
-int ieee802_1x_ckn_128bits_aes_cmac(const u8 *msk, const u8 *mac1,
-				    const u8 *mac2, const u8 *sid,
-				    size_t sid_bytes, u8 *ckn)
+int ieee802_1x_ckn_aes_cmac(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			    const u8 *mac2, const u8 *sid,
+			    size_t sid_bytes, u8 *ckn)
 {
 	int res;
 	u8 *context;
@@ -122,8 +121,8 @@ int ieee802_1x_ckn_128bits_aes_cmac(const u8 *msk, const u8 *mac1,
 	os_memcpy(context, sid, sid_bytes);
 	joint_two_mac(mac1, mac2, context + sid_bytes);
 
-	res = aes_kdf(msk, 128, "IEEE8021 EAP CKN", context, ctx_len * 8,
-		      128, ckn);
+	res = aes_kdf(msk, 8 * msk_bytes, "IEEE8021 EAP CKN",
+		      context, ctx_len * 8, 128, ckn);
 	os_free(context);
 	return res;
 }

src/pae/ieee802_1x_key.h

@@ -9,11 +9,11 @@
 #ifndef IEEE802_1X_KEY_H
 #define IEEE802_1X_KEY_H
 
-int ieee802_1x_cak_128bits_aes_cmac(const u8 *msk, const u8 *mac1,
-				    const u8 *mac2, u8 *cak);
-int ieee802_1x_ckn_128bits_aes_cmac(const u8 *msk, const u8 *mac1,
-				    const u8 *mac2, const u8 *sid,
-				    size_t sid_bytes, u8 *ckn);
+int ieee802_1x_cak_aes_cmac(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			    const u8 *mac2, u8 *cak, size_t cak_bytes);
+int ieee802_1x_ckn_aes_cmac(const u8 *msk, size_t msk_bytes, const u8 *mac1,
+			    const u8 *mac2, const u8 *sid,
+			    size_t sid_bytes, u8 *ckn);
 int ieee802_1x_kek_aes_cmac(const u8 *cak, size_t cak_bytes, const u8 *ckn,
 			    size_t ckn_bytes, u8 *kek, size_t kek_bytes);
 int ieee802_1x_ick_aes_cmac(const u8 *cak, size_t cak_bytes, const u8 *ckn,

wpa_supplicant/wpas_kay.c

@@ -357,8 +357,8 @@ void * ieee802_1x_notify_create_actor(struct wpa_supplicant *wpa_s,
 
 	/* Derive CAK from MSK */
 	cak->len = DEFAULT_KEY_LEN;
-	if (ieee802_1x_cak_128bits_aes_cmac(msk->key, wpa_s->own_addr,
-					    peer_addr, cak->key)) {
+	if (ieee802_1x_cak_aes_cmac(msk->key, msk->len, wpa_s->own_addr,
+				    peer_addr, cak->key, cak->len)) {
 		wpa_printf(MSG_ERROR,
 			   "IEEE 802.1X: Deriving CAK failed");
 		goto fail;
@@ -367,9 +367,8 @@ void * ieee802_1x_notify_create_actor(struct wpa_supplicant *wpa_s,
 
 	/* Derive CKN from MSK */
 	ckn->len = DEFAULT_CKN_LEN;
-	if (ieee802_1x_ckn_128bits_aes_cmac(msk->key, wpa_s->own_addr,
-					    peer_addr, sid, sid_len,
-					    ckn->name)) {
+	if (ieee802_1x_ckn_aes_cmac(msk->key, msk->len, wpa_s->own_addr,
+				    peer_addr, sid, sid_len, ckn->name)) {
 		wpa_printf(MSG_ERROR,
 			   "IEEE 802.1X: Deriving CKN failed");
 		goto fail;