[dhcp6relay] Add dhcpv6 option check (#10486)

dockers/docker-dhcp-relay/cli-plugin-tests/test_show_dhcp6relay_counters.py

@@ -32,6 +32,7 @@ expected_counts = """\
        Decline
  Relay-Forward
    Relay-Reply
+     Malformed
 
 """
 

dockers/docker-dhcp-relay/cli/show/plugins/show_dhcp_relay.py

@@ -12,7 +12,7 @@ from swsscommon.swsscommon import SonicV2Connector
 DHCPv6_COUNTER_TABLE = 'DHCPv6_COUNTER_TABLE'
 
 # DHCPv6 Counter Messages
-messages = ["Unknown", "Solicit", "Advertise", "Request", "Confirm", "Renew", "Rebind", "Reply", "Release", "Decline", "Relay-Forward", "Relay-Reply"]
+messages = ["Unknown", "Solicit", "Advertise", "Request", "Confirm", "Renew", "Rebind", "Reply", "Release", "Decline", "Relay-Forward", "Relay-Reply", "Malformed"]
 
 # DHCP_RELAY Config Table
 DHCP_RELAY = 'DHCP_RELAY'

src/dhcp6relay/src/relay.cpp

@@ -49,18 +49,19 @@ const struct sock_fprog ether_relay_fprog = {
 
 /* DHCPv6 Counter */
 uint64_t counters[DHCPv6_MESSAGE_TYPE_COUNT];
-std::map<int, std::string> counterMap = {{0, "Unknown"},
+std::map<int, std::string> counterMap = {{DHCPv6_MESSAGE_TYPE_UNKNOWN, "Unknown"},
-                                      {1, "Solicit"},
+                                      {DHCPv6_MESSAGE_TYPE_SOLICIT, "Solicit"},
-                                      {2, "Advertise"},
+                                      {DHCPv6_MESSAGE_TYPE_ADVERTISE, "Advertise"},
-                                      {3, "Request"},
+                                      {DHCPv6_MESSAGE_TYPE_REQUEST, "Request"},
-                                      {4, "Confirm"},
+                                      {DHCPv6_MESSAGE_TYPE_CONFIRM, "Confirm"},
-                                      {5, "Renew"},
+                                      {DHCPv6_MESSAGE_TYPE_RENEW, "Renew"},
-                                      {6, "Rebind"},
+                                      {DHCPv6_MESSAGE_TYPE_REBIND, "Rebind"},
-                                      {7, "Reply"},
+                                      {DHCPv6_MESSAGE_TYPE_REPLY, "Reply"},
-                                      {8, "Release"},
+                                      {DHCPv6_MESSAGE_TYPE_RELEASE, "Release"},
-                                      {9, "Decline"},
+                                      {DHCPv6_MESSAGE_TYPE_DECLINE, "Decline"},
-                                      {12, "Relay-Forward"},
+                                      {DHCPv6_MESSAGE_TYPE_RELAY_FORW, "Relay-Forward"},
-                                      {13, "Relay-Reply"}};
+                                      {DHCPv6_MESSAGE_TYPE_RELAY_REPL, "Relay-Reply"},
+                                      {DHCPv6_MESSAGE_TYPE_MALFORMED, "Malformed"}};
 
 /**
  * @code                void initialize_counter(swss::DBConnector *db, std::string counterVlan);
@@ -85,6 +86,7 @@ void initialize_counter(swss::DBConnector *db, std::string counterVlan) {
     db->hset(counterVlan, "Decline", toString(counters[DHCPv6_MESSAGE_TYPE_DECLINE]));
     db->hset(counterVlan, "Relay-Forward", toString(counters[DHCPv6_MESSAGE_TYPE_RELAY_FORW]));
     db->hset(counterVlan, "Relay-Reply", toString(counters[DHCPv6_MESSAGE_TYPE_RELAY_REPL]));
+    db->hset(counterVlan, "Malformed", toString(counters[DHCPv6_MESSAGE_TYPE_MALFORMED]));
 }
 
 /**
@@ -622,6 +624,8 @@ void callback(evutil_socket_t fd, short event, void *arg) {
     current_position = tmp;
 
     auto msg = parse_dhcpv6_hdr(current_position);
+    auto option_position = current_position + sizeof(struct dhcpv6_msg);
+
     counters[msg->msg_type]++;
     std::string counterVlan = counter_table;
     update_counter(config->db, counterVlan.append(config->interface), msg->msg_type);
@@ -632,9 +636,29 @@ void callback(evutil_socket_t fd, short event, void *arg) {
             relay_relay_forw(config->local_sock, current_position, ntohs(udp_header->len) - sizeof(udphdr), ip_header, config);
             break;
         }
+        case DHCPv6_MESSAGE_TYPE_SOLICIT:
+        case DHCPv6_MESSAGE_TYPE_REQUEST: 
+        case DHCPv6_MESSAGE_TYPE_RENEW:
+        case DHCPv6_MESSAGE_TYPE_REBIND:
+        case DHCPv6_MESSAGE_TYPE_RELEASE:
+        case DHCPv6_MESSAGE_TYPE_DECLINE:
+        {
+            while (option_position - message_buffer < len) {
+                auto option = parse_dhcpv6_opt(option_position, &tmp);
+                option_position = tmp;
+                if(ntohs(option->option_code) > DHCPv6_OPTION_LIMIT) {
+                    counters[DHCPv6_MESSAGE_TYPE_MALFORMED]++;
+                    update_counter(config->db, counterVlan.append(config->interface), DHCPv6_MESSAGE_TYPE_MALFORMED);
+                    syslog(LOG_WARNING, "DHCPv6 option is invalid or contains malformed payload\n");
+                    return;
+                }
+            }
+            relay_client(config->local_sock, current_position, ntohs(udp_header->len) - sizeof(udphdr), ip_header, ether_header, config);
+            break;
+        }
         default:
         {
-            relay_client(config->local_sock, current_position, ntohs(udp_header->len) - sizeof(udphdr), ip_header, ether_header, config);
+            syslog(LOG_WARNING, "DHCPv6 client message received was not relayed\n");
             break;
         }
     }

src/dhcp6relay/src/relay.h

@@ -16,6 +16,7 @@
 #define RELAY_PORT 547
 #define CLIENT_PORT 546
 #define HOP_LIMIT 8     //HOP_LIMIT reduced from 32 to 8 as stated in RFC8415
+#define DHCPv6_OPTION_LIMIT 56      // DHCPv6 option code greater than 56 are currently unassigned
 
 #define lengthof(A) (sizeof (A) / sizeof (A)[0])
 
@@ -37,6 +38,7 @@ typedef enum
     DHCPv6_MESSAGE_TYPE_DECLINE = 9,
     DHCPv6_MESSAGE_TYPE_RELAY_FORW = 12,
     DHCPv6_MESSAGE_TYPE_RELAY_REPL = 13,
+    DHCPv6_MESSAGE_TYPE_MALFORMED = 14,
 
     DHCPv6_MESSAGE_TYPE_COUNT
 } dhcp_message_type_t;