From b678ed1efc50e8da4638d962f8eac13312a4048f Mon Sep 17 00:00:00 2001
From: michael-dev <michael-dev@fami-braun.de>
Date: Tue, 15 Aug 2017 17:21:03 +0200
Subject: [PATCH] macsec: Make pre-shared CKN variable length

IEEE Std 802.1X-2010, 9.3.1 defines following restrictions for CKN:

"MKA places no restriction on the format of the CKN, save that it comprise
an integral number of octets, between 1 and 32 (inclusive), and that all
potential members of the CA use the same CKN. No further constraints are
placed on the CKNs used with PSKs, ..."

Hence do not require a 32 octet long CKN but instead allow a shorter CKN
to be configured.

This fixes interoperability with some Aruba switches, that do not accept
a 32 octet long CKN (only support shorter ones).

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>
---
 wpa_supplicant/config.c      | 19 +++++++++++++++----
 wpa_supplicant/config_ssid.h |  5 +++--
 wpa_supplicant/wpas_kay.c    |  2 +-
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/wpa_supplicant/config.c b/wpa_supplicant/config.c
index 46792e7f0..a0293d2b7 100644
--- a/wpa_supplicant/config.c
+++ b/wpa_supplicant/config.c
@@ -2020,8 +2020,18 @@ static int wpa_config_parse_mka_ckn(const struct parse_data *data,
 				    struct wpa_ssid *ssid, int line,
 				    const char *value)
 {
-	if (hexstr2bin(value, ssid->mka_ckn, MACSEC_CKN_LEN) ||
-	    value[MACSEC_CKN_LEN * 2] != '\0') {
+	size_t len;
+
+	len = os_strlen(value);
+	if (len > 2 * MACSEC_CKN_MAX_LEN || /* too long */
+	    len < 2 || /* too short */
+	    len % 2 != 0 /* not an integral number of bytes */) {
+		wpa_printf(MSG_ERROR, "Line %d: Invalid MKA-CKN '%s'.",
+			   line, value);
+		return -1;
+	}
+	ssid->mka_ckn_len = len / 2;
+	if (hexstr2bin(value, ssid->mka_ckn, ssid->mka_ckn_len)) {
 		wpa_printf(MSG_ERROR, "Line %d: Invalid MKA-CKN '%s'.",
 			   line, value);
 		return -1;
@@ -2029,7 +2039,8 @@ static int wpa_config_parse_mka_ckn(const struct parse_data *data,
 
 	ssid->mka_psk_set |= MKA_PSK_SET_CKN;
 
-	wpa_hexdump_key(MSG_MSGDUMP, "MKA-CKN", ssid->mka_ckn, MACSEC_CKN_LEN);
+	wpa_hexdump_key(MSG_MSGDUMP, "MKA-CKN", ssid->mka_ckn,
+			ssid->mka_ckn_len);
 	return 0;
 }
 
@@ -2051,7 +2062,7 @@ static char * wpa_config_write_mka_ckn(const struct parse_data *data,
 {
 	if (!(ssid->mka_psk_set & MKA_PSK_SET_CKN))
 		return NULL;
-	return wpa_config_write_string_hex(ssid->mka_ckn, MACSEC_CKN_LEN);
+	return wpa_config_write_string_hex(ssid->mka_ckn, ssid->mka_ckn_len);
 }
 
 #endif /* NO_CONFIG_WRITE */
diff --git a/wpa_supplicant/config_ssid.h b/wpa_supplicant/config_ssid.h
index deba9d973..665437de1 100644
--- a/wpa_supplicant/config_ssid.h
+++ b/wpa_supplicant/config_ssid.h
@@ -821,8 +821,9 @@ struct wpa_ssid {
 	/**
 	 * mka_ckn - MKA pre-shared CKN
 	 */
-#define MACSEC_CKN_LEN 32
-	u8 mka_ckn[MACSEC_CKN_LEN];
+#define MACSEC_CKN_MAX_LEN 32
+	size_t mka_ckn_len;
+	u8 mka_ckn[MACSEC_CKN_MAX_LEN];
 
 	/**
 	 * mka_cak - MKA pre-shared CAK
diff --git a/wpa_supplicant/wpas_kay.c b/wpa_supplicant/wpas_kay.c
index d3d06b8ae..c662bbbeb 100644
--- a/wpa_supplicant/wpas_kay.c
+++ b/wpa_supplicant/wpas_kay.c
@@ -414,7 +414,7 @@ void * ieee802_1x_create_preshared_mka(struct wpa_supplicant *wpa_s,
 	cak->len = MACSEC_CAK_LEN;
 	os_memcpy(cak->key, ssid->mka_cak, cak->len);
 
-	ckn->len = MACSEC_CKN_LEN;
+	ckn->len = ssid->mka_ckn_len;
 	os_memcpy(ckn->name, ssid->mka_ckn, ckn->len);
 
 	res = ieee802_1x_kay_create_mka(wpa_s->kay, ckn, cak, 0, PSK, FALSE);