From 835822d404c507d1bad223d87eae24d0ff634918 Mon Sep 17 00:00:00 2001
From: Jouni Malinen <j@w1.fi>
Date: Sun, 16 Dec 2012 19:46:10 +0200
Subject: [PATCH] WNM: Fix GTK/IGTK encoding in WNM-Sleep Mode Exit frame

These subelements do not use AES key wrap (MFP is used instead).

Signed-hostap: Jouni Malinen <j@w1.fi>
---
 src/ap/wpa_auth.c | 112 ++++++++++++++--------------------------------
 1 file changed, 33 insertions(+), 79 deletions(-)

diff --git a/src/ap/wpa_auth.c b/src/ap/wpa_auth.c
index 0dc3f58a5..2c70149a1 100644
--- a/src/ap/wpa_auth.c
+++ b/src/ap/wpa_auth.c
@@ -2444,108 +2444,62 @@ void wpa_set_wnmsleep(struct wpa_state_machine *sm, int flag)
 
 int wpa_wnmsleep_gtk_subelem(struct wpa_state_machine *sm, u8 *pos)
 {
-	u8 *subelem;
 	struct wpa_group *gsm = sm->group;
-	size_t subelem_len, pad_len;
-	const u8 *key;
-	size_t key_len;
-	u8 keybuf[32];
-
-	/* GTK subslement */
-	key_len = gsm->GTK_len;
-	if (key_len > sizeof(keybuf))
-		return 0;
-
-	/*
-	 * Pad key for AES Key Wrap if it is not multiple of 8 bytes or is less
-	 * than 16 bytes.
-	 */
-	pad_len = key_len % 8;
-	if (pad_len)
-		pad_len = 8 - pad_len;
-	if (key_len + pad_len < 16)
-		pad_len += 8;
-	if (pad_len) {
-		os_memcpy(keybuf, gsm->GTK[gsm->GN - 1], key_len);
-		os_memset(keybuf + key_len, 0, pad_len);
-		keybuf[key_len] = 0xdd;
-		key_len += pad_len;
-		key = keybuf;
-	} else
-		key = gsm->GTK[gsm->GN - 1];
+	u8 *start = pos;
 
 	/*
+	 * GTK subelement:
 	 * Sub-elem ID[1] | Length[1] | Key Info[2] | Key Length[1] | RSC[8] |
-	 * Key[5..32] | 8 padding.
+	 * Key[5..32]
 	 */
-	subelem_len = 13 + key_len + 8;
-	subelem = os_zalloc(subelem_len);
-	if (subelem == NULL)
-		return 0;
-
-	subelem[0] = WNM_SLEEP_SUBELEM_GTK;
-	subelem[1] = 11 + key_len + 8;
+	*pos++ = WNM_SLEEP_SUBELEM_GTK;
+	*pos++ = 11 + gsm->GTK_len;
 	/* Key ID in B0-B1 of Key Info */
-	WPA_PUT_LE16(&subelem[2], gsm->GN & 0x03);
-	subelem[4] = gsm->GTK_len;
-	if (wpa_auth_get_seqnum(sm->wpa_auth, NULL, gsm->GN, subelem + 5) != 0)
-	{
-		os_free(subelem);
+	WPA_PUT_LE16(pos, gsm->GN & 0x03);
+	pos += 2;
+	*pos++ = gsm->GTK_len;
+	if (wpa_auth_get_seqnum(sm->wpa_auth, NULL, gsm->GN, pos) != 0)
 		return 0;
-	}
-	if (aes_wrap(sm->PTK.kek, key_len / 8, key, subelem + 13)) {
-		os_free(subelem);
-		return 0;
-	}
+	pos += 8;
+	os_memcpy(pos, gsm->GTK[gsm->GN - 1], gsm->GTK_len);
+	pos += gsm->GTK_len;
 
-	os_memcpy(pos, subelem, subelem_len);
-
-	wpa_hexdump_key(MSG_DEBUG, "Plaintext GTK",
+	wpa_printf(MSG_DEBUG, "WNM: GTK Key ID %u in WNM-Sleep Mode exit",
+		   gsm->GN);
+	wpa_hexdump_key(MSG_DEBUG, "WNM: GTK in WNM-Sleep Mode exit",
 			gsm->GTK[gsm->GN - 1], gsm->GTK_len);
-	os_free(subelem);
 
-	return subelem_len;
+	return pos - start;
 }
 
 
 #ifdef CONFIG_IEEE80211W
 int wpa_wnmsleep_igtk_subelem(struct wpa_state_machine *sm, u8 *pos)
 {
-	u8 *subelem, *ptr;
 	struct wpa_group *gsm = sm->group;
-	size_t subelem_len;
+	u8 *start = pos;
 
-	/* IGTK subelement
-	 * Sub-elem ID[1] | Length[1] | KeyID[2] | PN[6] |
-	 * Key[16] | 8 padding */
-	subelem_len = 1 + 1 + 2 + 6 + WPA_IGTK_LEN + 8;
-	subelem = os_zalloc(subelem_len);
-	if (subelem == NULL)
+	/*
+	 * IGTK subelement:
+	 * Sub-elem ID[1] | Length[1] | KeyID[2] | PN[6] | Key[16]
+	 */
+	*pos++ = WNM_SLEEP_SUBELEM_IGTK;
+	*pos++ = 2 + 6 + WPA_IGTK_LEN;
+	WPA_PUT_LE16(pos, gsm->GN_igtk);
+	pos += 2;
+	if (wpa_auth_get_seqnum(sm->wpa_auth, NULL, gsm->GN_igtk, pos) != 0)
 		return 0;
+	pos += 6;
 
-	ptr = subelem;
-	*ptr++ = WNM_SLEEP_SUBELEM_IGTK;
-	*ptr++ = subelem_len - 2;
-	WPA_PUT_LE16(ptr, gsm->GN_igtk);
-	ptr += 2;
-	if (wpa_auth_get_seqnum(sm->wpa_auth, NULL, gsm->GN_igtk, ptr) != 0) {
-		os_free(subelem);
-		return 0;
-	}
-	ptr += 6;
-	if (aes_wrap(sm->PTK.kek, WPA_IGTK_LEN / 8,
-		     gsm->IGTK[gsm->GN_igtk - 4], ptr)) {
-		os_free(subelem);
-		return -1;
-	}
+	os_memcpy(pos, gsm->IGTK[gsm->GN_igtk - 4], WPA_IGTK_LEN);
+	pos += WPA_IGTK_LEN;
 
-	os_memcpy(pos, subelem, subelem_len);
-
-	wpa_hexdump_key(MSG_DEBUG, "Plaintext IGTK",
+	wpa_printf(MSG_DEBUG, "WNM: IGTK Key ID %u in WNM-Sleep Mode exit",
+		   gsm->GN_igtk);
+	wpa_hexdump_key(MSG_DEBUG, "WNM: IGTK in WNM-Sleep Mode exit",
 			gsm->IGTK[gsm->GN_igtk - 4], WPA_IGTK_LEN);
-	os_free(subelem);
 
-	return subelem_len;
+	return pos - start;
 }
 #endif /* CONFIG_IEEE80211W */
 #endif /* CONFIG_WNM */