V3 LLDP: Add packet validation (system name and description)

LLDP type system name and system description should
be with in 255 characters and unique.

Let's add the validation to discard corrupt packets.

diff --git a/src/libsystemd-network/sd-lldp.c b/src/libsystemd-network/sd-lldp.c
index a63cdf1..bb4314b 100644 (file)
--- a/src/libsystemd-network/sd-lldp.c
+++ b/src/libsystemd-network/sd-lldp.c
@@ -145,12 +145,9 @@ static int lldp_receive_frame(sd_lldp *lldp, tlv_packet *tlv) {
 
 /* 10.3.2 LLDPDU validation: rxProcessFrame() */
 int lldp_handle_packet(tlv_packet *tlv, uint16_t length) {
+        bool system_description = false, system_name = false, chassis_id = false;
+        bool malformed = false, port_id = false, ttl = false, end = false;
         uint16_t type, len, i, l, t;
-        bool chassis_id = false;
-        bool malformed = false;
-        bool port_id = false;
-        bool ttl = false;
-        bool end = false;
         lldp_port *port;
         uint8_t *p, *q;
         sd_lldp *lldp;
@@ -231,8 +228,7 @@ int lldp_handle_packet(tlv_packet *tlv, uint16_t length) {
                         }
 
                         /* Look what subtype it has */
-                        if (*q == LLDP_CHASSIS_SUBTYPE_RESERVED ||
-                            *q > LLDP_CHASSIS_SUBTYPE_LOCALLY_ASSIGNED) {
+                        if (*q == LLDP_CHASSIS_SUBTYPE_RESERVED || *q > LLDP_CHASSIS_SUBTYPE_LOCALLY_ASSIGNED) {
                                 log_lldp("Unknown subtype: %d found in Chassis ID TLV. Dropping.", *q);
 
                                 malformed = true;
@@ -260,8 +256,7 @@ int lldp_handle_packet(tlv_packet *tlv, uint16_t length) {
                         }
 
                         /* Look what subtype it has */
-                        if (*q == LLDP_PORT_SUBTYPE_RESERVED ||
-                            *q > LLDP_PORT_SUBTYPE_LOCALLY_ASSIGNED) {
+                        if (*q == LLDP_PORT_SUBTYPE_RESERVED || *q > LLDP_PORT_SUBTYPE_LOCALLY_ASSIGNED) {
                                 log_lldp("Unknown subtype: %d found in Port ID TLV. Dropping.", *q);
 
                                 malformed = true;
@@ -291,6 +286,41 @@ int lldp_handle_packet(tlv_packet *tlv, uint16_t length) {
                         ttl = true;
 
                         break;
+                case LLDP_TYPE_SYSTEM_NAME:
+
+                        /* According to RFC 1035 the length of a FQDN is limited to 255 characters */
+                        if (len > 255) {
+                                log_lldp("Received invalid systemd name length: %d. Dropping.", len);
+                                malformed = true;
+                                goto out;
+                        }
+
+                        if (system_name) {
+                                log_lldp("Duplicate system name found. Dropping.");
+                                malformed = true;
+                                goto out;
+                        }
+
+                        system_name = true;
+
+                        break;
+                case LLDP_TYPE_SYSTEM_DESCRIPTION:
+
+                        /* 0 <= n <= 255 octets */
+                        if (len > 255) {
+                                log_lldp("Received invalid system description length: %d. Dropping.", len);
+                                malformed = true;
+                                goto out;
+                        }
+
+                        if (system_description) {
+                                log_lldp("Duplicate system description found. Dropping.");
+                                malformed = true;
+                                goto out;
+                        }
+
+                        system_description = true;
+                        break;
                 default:
 
                         if (len == 0) {