STUN: fix detection of DTLS

Fix a memory leak ``` ==97697==ERROR: LeakSanitizer: detected memory leaks Direct leak of 16 byte(s) in 1 object(s) allocated from: #0 0x55a6967cfa7e in malloc (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader+0x701a7e) (BuildId: c7124999fa1ccc54346fa7bd536d8eab88c3ea01) ntop#1 0x55a696972ab5 in ndpi_malloc /home/ivan/svnrepos/nDPI/src/lib/ndpi_memory.c:60:25 ntop#2 0x55a696972da0 in ndpi_strdup /home/ivan/svnrepos/nDPI/src/lib/ndpi_memory.c:113:13 ntop#3 0x55a696b7658d in processClientServerHello /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:2394:46 ntop#4 0x55a696b86e81 in processTLSBlock /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:897:5 ntop#5 0x55a696b80649 in ndpi_search_tls_udp /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:1262:11 ntop#6 0x55a696b67a57 in ndpi_search_tls_wrapper /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:2751:5 ntop#7 0x55a696b67758 in switch_to_tls /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:1408:3 ntop#8 0x55a696c47810 in stun_search_again /home/ivan/svnrepos/nDPI/src/lib/protocols/stun.c:422:4 ntop#9 0x55a6968a22af in ndpi_process_extra_packet /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:7247:9 ntop#10 0x55a6968acd6f in ndpi_internal_detection_process_packet /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:7746:5 ntop#11 0x55a6968aba3f in ndpi_detection_process_packet /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:8013:22 ntop#12 0x55a69683d30e in packet_processing /home/ivan/svnrepos/nDPI/fuzz/../example/reader_util.c:1723:31 ntop#13 0x55a69683d30e in ndpi_workflow_process_packet /home/ivan/svnrepos/nDPI/fuzz/../example/reader_util.c:2440:10 ntop#14 0x55a69680f08f in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:135:7 [...] SUMMARY: AddressSanitizer: 16 byte(s) leaked in 1 allocation(s). ``` Found by oss-fuzzer See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=64564
IvanNardi · Nov 29, 2023 · 802d129 · 802d129
1 parent d85f859
commit 802d129
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Showing 4 changed files with 50 additions and 10 deletions.
diff --git a/fuzz/fuzz_ndpi_reader.c b/fuzz/fuzz_ndpi_reader.c
@@ -37,6 +37,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
   int r;
   char errbuf[PCAP_ERRBUF_SIZE];
   NDPI_PROTOCOL_BITMASK all;
+  NDPI_PROTOCOL_BITMASK debug_bitmask;
   u_int i;
   FILE *fd;
 
@@ -60,6 +61,10 @@ int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
     NDPI_BITMASK_SET_ALL(all);
     ndpi_set_protocol_detection_bitmask2(workflow->ndpi_struct, &all);
 
+    NDPI_BITMASK_SET_ALL(debug_bitmask);
+    ndpi_set_log_level(workflow->ndpi_struct, 4);
+    ndpi_set_debug_bitmask(workflow->ndpi_struct, debug_bitmask);
+
     ndpi_load_protocols_file(workflow->ndpi_struct, "protos.txt");
     ndpi_load_categories_file(workflow->ndpi_struct, "categories.txt", NULL);
     ndpi_load_risk_domain_file(workflow->ndpi_struct, "risky_domains.txt");

diff --git a/src/lib/protocols/stun.c b/src/lib/protocols/stun.c
@@ -353,6 +353,8 @@ static int stun_search_again(struct ndpi_detection_module_struct *ndpi_struct,
   u_int16_t app_proto = NDPI_PROTOCOL_UNKNOWN;
   u_int32_t unused;
   int first_dtls_pkt = 0;
+  u_int16_t old_proto_stack[2];
+  ndpi_protocol_category_t old_category;
 
   NDPI_LOG_DBG2(ndpi_struct, "Packet counter %d protos %d/%d\n", flow->packet_counter,
                 flow->detected_protocol_stack[0], flow->detected_protocol_stack[1]);
@@ -396,6 +398,10 @@ static int stun_search_again(struct ndpi_detection_module_struct *ndpi_struct,
          * the easiest (!?) solution is to remove everything, and let the TLS dissector
 	   to set both master (i.e. DTLS) and subprotocol (if any) */
 
+      /* In same rare cases, with malformed/fuzzed traffic, `is_dtls()` might return false
+         positives. In that case, the TLS dissector doesn't set the master protocol, so we
+         need to rollback to the current state */
+
       if(packet->tcp) {
         /* TODO: TLS code assumes that DTLS is only over UDP */
         NDPI_LOG_DBG(ndpi_struct, "Ignoring DTLS over TCP\n");
@@ -407,6 +413,11 @@ static int stun_search_again(struct ndpi_detection_module_struct *ndpi_struct,
             /* First DTLS packet of the flow */
             first_dtls_pkt = 1;
 
+	    /* We might need to rollback this change... */
+	    old_proto_stack[0] = flow->detected_protocol_stack[0];
+	    old_proto_stack[1] = flow->detected_protocol_stack[1];
+	    old_category = flow->category;
+
             /* TODO: right way? It is a bit scary... do we need to reset something else too? */
             reset_detected_protocol(ndpi_struct, flow);
             change_category(ndpi_struct, flow, NDPI_PROTOCOL_CATEGORY_UNSPECIFIED);
@@ -423,6 +434,23 @@ static int stun_search_again(struct ndpi_detection_module_struct *ndpi_struct,
 
 	  NDPI_LOG_DBG(ndpi_struct, "(%d/%d)\n",
                        flow->detected_protocol_stack[0], flow->detected_protocol_stack[1]);
+
+	  /* If this is not a real DTLS packet, we need to restore the old state */
+          if(flow->detected_protocol_stack[0] == NDPI_PROTOCOL_UNKNOWN &&
+             first_dtls_pkt) {
+            NDPI_LOG_DBG(ndpi_struct, "Switch to TLS failed. Rollback to old classification\n");
+
+            ndpi_set_detected_protocol(ndpi_struct, flow,
+                                       old_proto_stack[1], old_proto_stack[0],
+                                       NDPI_CONFIDENCE_DPI);
+            change_category(ndpi_struct, flow, old_category);
+
+            flow->stun.maybe_dtls = 0;
+            flow->max_extra_packets_to_check -= 10;
+
+            NDPI_LOG_DBG(ndpi_struct, "(%d/%d)\n",
+                         flow->detected_protocol_stack[0], flow->detected_protocol_stack[1]);
+          }
         }
       }
     }

diff --git a/tests/cfgs/default/pcap/stun.pcap b/tests/cfgs/default/pcap/stun.pcap
diff --git a/tests/cfgs/default/result/stun.pcap.out b/tests/cfgs/default/result/stun.pcap.out
@@ -1,40 +1,47 @@
-Guessed flow protos:	0
+Guessed flow protos:	1
 
 DPI Packets (TCP):	9	(4.50 pkts/flow)
-DPI Packets (UDP):	12	(3.00 pkts/flow)
+DPI Packets (UDP):	16	(3.20 pkts/flow)
 DPI Packets (other):	1	(1.00 pkts/flow)
-Confidence DPI              : 7 (flows)
-Num dissector calls: 22 (3.14 diss/flow)
+Confidence DPI              : 8 (flows)
+Num dissector calls: 28 (3.50 diss/flow)
 LRU cache ookla:      0/0/0 (insert/search/found)
 LRU cache bittorrent: 0/0/0 (insert/search/found)
 LRU cache zoom:       0/0/0 (insert/search/found)
-LRU cache stun:       8/28/0 (insert/search/found)
-LRU cache tls_cert:   0/0/0 (insert/search/found)
+LRU cache stun:       8/32/0 (insert/search/found)
+LRU cache tls_cert:   0/1/0 (insert/search/found)
 LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 LRU cache stun_zoom:  0/0/0 (insert/search/found)
 Automa host:          0/0 (search/found)
 Automa domain:        0/0 (search/found)
 Automa tls cert:      0/0 (search/found)
 Automa risk mask:     1/0 (search/found)
-Automa common alpns:  0/0 (search/found)
-Patricia risk mask:   8/0 (search/found)
+Automa common alpns:  2/2 (search/found)
+Patricia risk mask:   10/0 (search/found)
 Patricia risk mask IPv6: 2/0 (search/found)
 Patricia risk:        1/0 (search/found)
 Patricia risk IPv6:   1/0 (search/found)
-Patricia protocols:   8/4 (search/found)
+Patricia protocols:   9/5 (search/found)
 Patricia protocols IPv6: 2/0 (search/found)
 
+DTLS	4	766	1
 Skype_TeamsCall	15	2124	1
 STUN	62	7620	2
 ICMP	1	122	1
 GoogleHangoutDuo	41	7228	2
 FacebookVoip	75	10554	1
 
+JA3 Host Stats: 
+		 IP Address                  	 # JA3C     
+	1	 192.168.43.169           	 1      
+
+
 	1	UDP 192.168.12.169:38123 <-> 31.13.86.54:40003 [proto: 78.268/STUN.FacebookVoip][IP: 119/Facebook][ClearText][Confidence: DPI][DPI packets: 2][cat: VoIP/10][40 pkts/6134 bytes <-> 35 pkts/4420 bytes][Goodput ratio: 73/67][10.09 sec][Hostname/SNI: turner.facebook][bytes ratio: 0.162 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 0/0 260/331 6004/5997 1040/1126][Pkt Len c2s/s2c min/avg/max/stddev: 70/68 153/126 190/174 31/39][Risk: ** Known Proto on Non Std Port **][Risk Score: 50][PLAIN TEXT (unauthorized)][Plen Bins: 8,14,9,28,40,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
 	2	UDP 192.168.12.169:49153 <-> 142.250.82.99:3478 [proto: 78.201/STUN.GoogleHangoutDuo][IP: 126/Google][ClearText][Confidence: DPI][DPI packets: 1][cat: VoIP/10][18 pkts/2856 bytes <-> 15 pkts/3436 bytes][Goodput ratio: 74/82][2.12 sec][bytes ratio: -0.092 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 8/0 88/153 699/625 177/222][Pkt Len c2s/s2c min/avg/max/stddev: 107/76 159/229 588/1240 107/297][PLAIN TEXT (BwlkYDtFJ)][Plen Bins: 0,6,57,21,6,0,0,0,0,0,0,0,0,0,0,0,0,6,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0]
 	3	UDP [3516:bf0b:fc53:75e7:70af:f67f:8e49:f603]:56880 <-> [2a38:e156:8167:a333:face:b00c::24d9]:3478 [proto: 78/STUN][IP: 0/Unknown][ClearText][Confidence: DPI][DPI packets: 5][cat: Network/14][21 pkts/1722 bytes <-> 21 pkts/2226 bytes][Goodput ratio: 24/41][191.49 sec][bytes ratio: -0.128 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 2/2 9451/9451 10358/10358 2441/2441][Pkt Len c2s/s2c min/avg/max/stddev: 82/106 82/106 82/106 0/0][PLAIN TEXT (WOBTrOXR)][Plen Bins: 50,50,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
 	4	TCP 87.47.100.17:3478 <-> 54.1.57.155:37257 [proto: 78/STUN][IP: 0/Unknown][ClearText][Confidence: DPI][DPI packets: 6][cat: Network/14][9 pkts/1494 bytes <-> 11 pkts/2178 bytes][Goodput ratio: 60/67][0.95 sec][Hostname/SNI: apps-host.com][bytes ratio: -0.186 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 0/0 104/96 267/252 102/93][Pkt Len c2s/s2c min/avg/max/stddev: 74/94 166/198 234/354 41/65][PLAIN TEXT (Unauthorized)][Plen Bins: 10,0,15,21,42,5,0,0,0,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
 	5	TCP 10.77.110.51:41588 <-> 10.206.50.239:42000 [VLAN: 1611][proto: 78.38/STUN.Skype_TeamsCall][IP: 0/Unknown][ClearText][Confidence: DPI][DPI packets: 3][cat: VoIP/10][7 pkts/1006 bytes <-> 8 pkts/1118 bytes][Goodput ratio: 58/57][1.05 sec][bytes ratio: -0.053 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 0/0 189/134 369/399 144/153][Pkt Len c2s/s2c min/avg/max/stddev: 70/64 144/140 164/172 31/43][Plen Bins: 0,0,25,75,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
 	6	UDP 192.168.12.169:43016 <-> 74.125.247.128:3478 [proto: 78.201/STUN.GoogleHangoutDuo][IP: 126/Google][ClearText][Confidence: DPI][DPI packets: 4][cat: VoIP/10][4 pkts/528 bytes <-> 4 pkts/408 bytes][Goodput ratio: 68/59][1.25 sec][Hostname/SNI: turn.l.google.com][bytes ratio: 0.128 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 9/23 342/409 974/1177 447/543][Pkt Len c2s/s2c min/avg/max/stddev: 62/74 132/102 198/122 61/19][PLAIN TEXT (BSnLfRxS6)][Plen Bins: 12,37,25,0,25,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
-	7	ICMP 192.168.12.169:0 -> 74.125.247.128:0 [proto: 81/ICMP][IP: 126/Google][ClearText][Confidence: DPI][DPI packets: 1][cat: Network/14][1 pkts/122 bytes -> 0 pkts/0 bytes][Goodput ratio: 65/0][< 1 sec][Risk: ** Unidirectional Traffic **][Risk Score: 10][Risk Info: No server to client traffic][PLAIN TEXT (62NfUD5)][Plen Bins: 0,0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
+	7	UDP 192.168.43.169:48854 <-> 134.224.90.111:8801 [proto: 30/DTLS][IP: 189/Zoom][Encrypted][Confidence: DPI][DPI packets: 4][3 pkts/660 bytes <-> 1 pkts/106 bytes][Goodput ratio: 81/60][0.12 sec][(Advertised) ALPNs: webrtc;c-webrtc][Risk: ** Known Proto on Non Std Port **** Missing SNI TLS Extn **][Risk Score: 100][DTLSv1.2][JA3C: 3e12a43c7535bb32beac3928f8fe905d][Firefox][PLAIN TEXT (DCBD09778680)][Plen Bins: 0,0,25,0,25,50,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
+	8	ICMP 192.168.12.169:0 -> 74.125.247.128:0 [proto: 81/ICMP][IP: 126/Google][ClearText][Confidence: DPI][DPI packets: 1][cat: Network/14][1 pkts/122 bytes -> 0 pkts/0 bytes][Goodput ratio: 65/0][< 1 sec][Risk: ** Unidirectional Traffic **][Risk Score: 10][Risk Info: No server to client traffic][PLAIN TEXT (62NfUD5)][Plen Bins: 0,0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]