Corrected PAN ID checking for NVM keys and MAC key remove on discovery

When NVM keys were used, PAN ID was not checked correctly. Now keys
are used only if PAN ID matches, and if EAPOL is initiated using
different PAN ID, previous keys are removed.
Modified functionality to remove only MAC keys when discovery is
started. EAPOL keys will remain valid and will be used on next
bootstart if same PAN ID is tried.

Author: Mika Leppänen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -2558,12 +2558,10 @@ void ws_bootstrap_trickle_timer(protocol_interface_info_entry_t *cur, uint16_t t
         // send PAN Configuration solicit
         if (cur->ws_info->pas_requests > PCS_MAX) {
             // if MAX PCS sent restart discovery
-            uint8_t empty_key[32];
-            memset(empty_key, 0, 32);
-            tr_debug("Restart???");
-            //Clear Key's
-            tr_debug("Remove not working GTK's");
-            ws_pae_controller_gtk_hash_update(cur, empty_key);
+
+            // Remove network keys from MAC
+            ws_pae_controller_nw_keys_remove(cur);
+
             ws_bootstrap_event_discovery_start(cur);
             return;
         }

source/6LoWPAN/ws/ws_pae_controller.c

@@ -393,6 +393,28 @@ int8_t ws_pae_controller_nw_key_index_update(protocol_interface_info_entry_t *in
     return 0;
 }
 
+void ws_pae_controller_nw_keys_remove(protocol_interface_info_entry_t *interface_ptr)
+{
+    pae_controller_t *controller = ws_pae_controller_get(interface_ptr);
+    if (!controller) {
+        return;
+    }
+
+    tr_info("NW keys remove");
+
+    if (controller->nw_keys_init_done) {
+        nw_key_t *nw_key = controller->nw_key;
+        for (uint8_t i = 0; i < GTK_NUM; i++) {
+            // Deletes the key if it is set
+            if (!sec_prot_keys_gtk_hash_empty(nw_key[i].hash)) {
+                tr_info("NW key remove: %i, slot: %i", i, nw_key[i].slot);
+                controller->nw_key_insert(interface_ptr, nw_key[i].slot, i, NULL);
+                memset(&nw_key[i], 0, sizeof(nw_key_t));
+            }
+        }
+    }
+}
+
 static void ws_pae_controller_nw_key_index_check_and_set(protocol_interface_info_entry_t *interface_ptr, uint8_t index)
 {
     pae_controller_t *controller = ws_pae_controller_get(interface_ptr);

source/6LoWPAN/ws/ws_pae_controller.h

@@ -338,6 +338,14 @@ int8_t ws_pae_controller_gtk_hash_update(protocol_interface_info_entry_t *interf
  */
 int8_t ws_pae_controller_nw_key_index_update(protocol_interface_info_entry_t *interface_ptr, uint8_t index);
 
+/**
+ * ws_pae_controller_nw_keys_remove remove network keys
+ *
+ * \param interface_ptr interface
+ *
+ */
+void ws_pae_controller_nw_keys_remove(protocol_interface_info_entry_t *interface_ptr);
+
 /**
  * ws_pae_controller_nw_key_insert network key insert callback
  *

source/6LoWPAN/ws/ws_pae_supp.c

@@ -79,7 +79,8 @@ const char *KEYS_FILE = "pae_keys";
 typedef struct {
     char network_name[33];                                 /**< Network name for keys */
     sec_prot_gtk_keys_t *gtks;                             /**< Link to GTKs */
-    uint16_t pan_id;                                       /**< PAN ID for keys */
+    uint16_t new_pan_id;                                   /**< new PAN ID indicated by bootstrap */
+    uint16_t key_pan_id;                                   /**< PAN ID for keys */
     bool updated : 1;                                      /**< Network info has been updated */
 } sec_prot_keys_nw_info_t;
 
@@ -159,13 +160,6 @@ int8_t ws_pae_supp_authenticate(protocol_interface_info_entry_t *interface_ptr,
         return -1;
     }
 
-    if (!dest_eui_64) {
-        pae_supp->sec_keys_nw_info.pan_id = dest_pan_id;
-        if (pae_supp->nw_keys_used_cnt > 1) {
-            pae_supp->nw_keys_used_cnt = 1;
-        }
-    }
-
     if (ws_pae_supp_nw_keys_valid_check(pae_supp, dest_pan_id) >= 0) {
         pae_supp->auth_completed(interface_ptr, true);
         return 0;
@@ -174,6 +168,16 @@ int8_t ws_pae_supp_authenticate(protocol_interface_info_entry_t *interface_ptr,
     // Delete GTKs
     sec_prot_keys_gtks_init(pae_supp->sec_keys_nw_info.gtks);
 
+    /* PAN ID has changed, delete key data associated with border router
+       i.e PMK, PTK, EA-IE data (border router EUI-64) */
+    if (pae_supp->sec_keys_nw_info.key_pan_id != 0xFFFF && pae_supp->sec_keys_nw_info.key_pan_id != dest_pan_id) {
+        sec_prot_keys_pmk_delete(&pae_supp->entry.sec_keys);
+        sec_prot_keys_ptk_delete(&pae_supp->entry.sec_keys);
+        sec_prot_keys_ptk_eui_64_delete(&pae_supp->entry.sec_keys);
+    }
+
+    pae_supp->sec_keys_nw_info.key_pan_id = dest_pan_id;
+
     // Prepare to receive new border router address
     pae_supp->new_br_eui_64_set = false;
 
@@ -203,8 +207,8 @@ int8_t ws_pae_supp_nw_info_set(protocol_interface_info_entry_t *interface_ptr, u
     }
 
     // PAN ID has been modified
-    if (pan_id != 0xffff && pan_id != pae_supp->sec_keys_nw_info.pan_id) {
-        pae_supp->sec_keys_nw_info.pan_id = pan_id;
+    if (pan_id != 0xffff && pan_id != pae_supp->sec_keys_nw_info.new_pan_id) {
+        pae_supp->sec_keys_nw_info.new_pan_id = pan_id;
         pae_supp->sec_keys_nw_info.updated = true;
     }
 
@@ -350,7 +354,7 @@ static int8_t ws_pae_supp_nvm_nw_info_write(pae_supp_t *pae_supp)
     nvm_tlv_list_t tlv_list;
     ns_list_init(&tlv_list);
 
-    nvm_tlv_entry_t *tlv_entry = ws_pae_nvm_store_nw_info_tlv_create(pae_supp->sec_keys_nw_info.pan_id,
+    nvm_tlv_entry_t *tlv_entry = ws_pae_nvm_store_nw_info_tlv_create(pae_supp->sec_keys_nw_info.key_pan_id,
                                                                      pae_supp->sec_keys_nw_info.network_name,
                                                                      &pae_supp->gtks);
     ns_list_add_to_end(&tlv_list, tlv_entry);
@@ -370,7 +374,7 @@ static int8_t ws_pae_supp_nvm_nw_info_read(pae_supp_t *pae_supp)
     ws_pae_nvm_store_tlv_file_read(NW_INFO_FILE, &tlv_list);
 
     ns_list_foreach_safe(nvm_tlv_entry_t, entry, &tlv_list) {
-        ws_pae_nvm_store_nw_info_tlv_read(entry, &pae_supp->sec_keys_nw_info.pan_id,
+        ws_pae_nvm_store_nw_info_tlv_read(entry, &pae_supp->sec_keys_nw_info.key_pan_id,
                                           pae_supp->sec_keys_nw_info.network_name,
                                           &pae_supp->gtks);
         ns_list_remove(&tlv_list, entry);
@@ -465,21 +469,18 @@ static int8_t ws_pae_supp_nw_keys_valid_check(pae_supp_t *pae_supp, uint16_t pan
         return -1;
     }
 
-    // First attempt to authenticate, checks if keys exists
-    if (pae_supp->nw_keys_used_cnt == 0 && pan_id == pae_supp->sec_keys_nw_info.pan_id) {
+    /* Checks if keys matches to PAN ID, and call inserts function that will update the
+       network keys as needed */
+    if (pan_id == pae_supp->sec_keys_nw_info.key_pan_id) {
+        tr_debug("Existing keys used, counter %i", pae_supp->nw_keys_used_cnt);
         if (pae_supp->nw_key_insert(pae_supp->interface_ptr, pae_supp->sec_keys_nw_info.gtks) >= 0) {
             tr_debug("Keys inserted");
-            pae_supp->nw_keys_used_cnt++;
-            return 0;
         }
-    }
-
-    if (pae_supp->nw_keys_used_cnt == 0) {
-        return -1;
-    } else {
-        tr_debug("Existing keys used, counter %i", pae_supp->nw_keys_used_cnt);
         pae_supp->nw_keys_used_cnt++;
         return 0;
+    } else {
+        pae_supp->nw_keys_used_cnt = 0;
+        return -1;
     }
 }
 
@@ -492,6 +493,8 @@ static void ws_pae_supp_keys_nw_info_init(sec_prot_keys_nw_info_t *sec_keys_nw_i
     memset(sec_keys_nw_info, 0, sizeof(sec_prot_keys_nw_info_t));
 
     sec_keys_nw_info->gtks = gtks;
+    sec_keys_nw_info->new_pan_id = 0xFFFF;
+    sec_keys_nw_info->key_pan_id = 0xFFFF;
     sec_keys_nw_info->updated = false;
 }
 

source/Security/protocols/sec_prot_keys.c

@@ -254,6 +254,13 @@ uint8_t *sec_prot_keys_ptk_eui_64_get(sec_prot_keys_t *sec_keys)
     return sec_keys->ptk_eui_64;
 }
 
+void sec_prot_keys_ptk_eui_64_delete(sec_prot_keys_t *sec_keys)
+{
+    memset(sec_keys->ptk_eui_64, 0, 8);
+    sec_keys->ptk_eui_64_set = false;
+    sec_keys->updated = true;
+}
+
 bool sec_prot_keys_ptk_lifetime_decrement(sec_prot_keys_t *sec_keys, uint32_t default_lifetime, uint8_t seconds)
 {
     if (!sec_keys->ptk_set) {

source/Security/protocols/sec_prot_keys.h

@@ -331,6 +331,14 @@ void sec_prot_keys_ptk_eui_64_write(sec_prot_keys_t *sec_keys, const uint8_t *eu
  */
 uint8_t *sec_prot_keys_ptk_eui_64_get(sec_prot_keys_t *sec_keys);
 
+/**
+ * sec_prot_keys_ptk_eui_64_delete deletes PTK EUI-64
+ *
+ * \param sec_keys security keys
+ *
+ */
+void sec_prot_keys_ptk_eui_64_delete(sec_prot_keys_t *sec_keys);
+
 /**
  * sec_prot_keys_ptk_lifetime_decrement decrements PTK lifetime
  *