mesh: Add variable length MTK support

This is needed as a part in enabling support for different pairwise
ciphers in mesh.

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

src/ap/sta_info.h

@@ -85,7 +85,8 @@ struct sta_info {
 	u8 my_nonce[WPA_NONCE_LEN];
 	u8 peer_nonce[WPA_NONCE_LEN];
 	u8 aek[32];	/* SHA256 digest length */
-	u8 mtk[16];
+	u8 mtk[WPA_TK_MAX_LEN];
+	size_t mtk_len;
 	u8 mgtk[16];
 	u8 sae_auth_retry;
 #endif /* CONFIG_MESH */

wpa_supplicant/mesh_mpm.c

@@ -793,8 +793,10 @@ static void mesh_mpm_plink_estab(struct wpa_supplicant *wpa_s,
 		MAC2STR(sta->addr));
 
 	if (conf->security & MESH_CONF_SEC_AMPE) {
+		wpa_hexdump_key(MSG_DEBUG, "mesh: MTK", sta->mtk, sta->mtk_len);
+		/* TODO: support for other ciphers */
 		wpa_drv_set_key(wpa_s, WPA_ALG_CCMP, sta->addr, 0, 0,
-				seq, sizeof(seq), sta->mtk, sizeof(sta->mtk));
+				seq, sizeof(seq), sta->mtk, sta->mtk_len);
 		wpa_drv_set_key(wpa_s, WPA_ALG_CCMP, sta->addr, 1, 0,
 				seq, sizeof(seq),
 				sta->mgtk, sizeof(sta->mgtk));
@@ -802,7 +804,6 @@ static void mesh_mpm_plink_estab(struct wpa_supplicant *wpa_s,
 				seq, sizeof(seq),
 				sta->mgtk, sizeof(sta->mgtk));
 
-		wpa_hexdump_key(MSG_DEBUG, "mtk:", sta->mtk, sizeof(sta->mtk));
 		wpa_hexdump_key(MSG_DEBUG, "mgtk:",
 				sta->mgtk, sizeof(sta->mgtk));
 	}

wpa_supplicant/mesh_rsn.c

@@ -445,9 +445,10 @@ int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta)
 	ptr += ETH_ALEN;
 	os_memcpy(ptr, max, ETH_ALEN);
 
+	sta->mtk_len = wpa_cipher_key_len(WPA_CIPHER_CCMP);
 	sha256_prf(sta->sae->pmk, SAE_PMK_LEN,
 		   "Temporal Key Derivation", context, sizeof(context),
-		   sta->mtk, sizeof(sta->mtk));
+		   sta->mtk, sta->mtk_len);
 	return 0;
 }