ip: fix possible missing trace indexes

Add safeguards when tracing packets to avoid cases where clear trace
was issue while buffers were held in reassembly.

Type: fix
Change-Id: I1bdd1e629e8bc08ce63913fd3c4b2327e47dec04
Signed-off-by: Klement Sekera <ksekera@cisco.com>

src/vnet/ip/reass/ip4_full_reass.c

@@ -342,6 +342,13 @@ ip4_full_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 {
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
   vnet_buffer_opaque_t *vnb = vnet_buffer (b);
+  if (pool_is_free_index
+      (vm->trace_main.trace_buffer_pool, vlib_buffer_get_trace_index (b)))
+    {
+      // this buffer's trace is gone
+      b->flags &= ~VLIB_BUFFER_IS_TRACED;
+      return;
+    }
   bool is_after_handoff = false;
   if (vlib_buffer_get_trace_thread (b) != vm->thread_index)
     {

src/vnet/ip/reass/ip4_sv_reass.c

@@ -235,6 +235,13 @@ ip4_sv_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 			u32 ip_proto, u16 l4_src_port, u16 l4_dst_port)
 {
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
+  if (pool_is_free_index
+      (vm->trace_main.trace_buffer_pool, vlib_buffer_get_trace_index (b)))
+    {
+      // this buffer's trace is gone
+      b->flags &= ~VLIB_BUFFER_IS_TRACED;
+      return;
+    }
   ip4_sv_reass_trace_t *t = vlib_add_trace (vm, node, b, sizeof (t[0]));
   if (reass)
     {

src/vnet/ip/reass/ip6_full_reass.c

@@ -319,6 +319,13 @@ ip6_full_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
   vnet_buffer_opaque_t *vnb = vnet_buffer (b);
   bool is_after_handoff = false;
+  if (pool_is_free_index
+      (vm->trace_main.trace_buffer_pool, vlib_buffer_get_trace_index (b)))
+    {
+      // this buffer's trace is gone
+      b->flags &= ~VLIB_BUFFER_IS_TRACED;
+      return;
+    }
   if (vlib_buffer_get_trace_thread (b) != vm->thread_index)
     {
       is_after_handoff = true;

src/vnet/ip/reass/ip6_sv_reass.c

@@ -228,6 +228,13 @@ ip6_sv_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 			u32 ip_proto, u16 l4_src_port, u16 l4_dst_port)
 {
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
+  if (pool_is_free_index
+      (vm->trace_main.trace_buffer_pool, vlib_buffer_get_trace_index (b)))
+    {
+      // this buffer's trace is gone
+      b->flags &= ~VLIB_BUFFER_IS_TRACED;
+      return;
+    }
   ip6_sv_reass_trace_t *t = vlib_add_trace (vm, node, b, sizeof (t[0]));
   if (reass)
     {

test/test_reassembly.py

@@ -170,6 +170,21 @@ class TestIPv4Reassembly(VppTestCase):
         self.verify_capture(packets)
         self.src_if.assert_nothing_captured()
 
+    def test_verify_clear_trace_mid_reassembly(self):
+        """ verify clear trace works mid-reassembly """
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(self.fragments_200[0:-1])
+        self.pg_start()
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.src_if.add_stream(self.fragments_200[-1])
+        self.pg_start()
+        packets = self.dst_if.get_capture(len(self.pkt_infos))
+        self.verify_capture(packets)
+
     def test_reversed(self):
         """ reverse order reassembly """
 
@@ -588,6 +603,42 @@ class TestIPv4SVReassembly(VppTestCase):
             self.assertEqual(sent[IP].dst, recvd[IP].dst)
             self.assertEqual(sent[Raw].payload, recvd[Raw].payload)
 
+    def test_verify_clear_trace_mid_reassembly(self):
+        """ verify clear trace works mid-reassembly """
+        payload_len = 1000
+        payload = ""
+        counter = 0
+        while len(payload) < payload_len:
+            payload += "%u " % counter
+            counter += 1
+
+        p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) /
+             IP(id=1, src=self.src_if.remote_ip4,
+                dst=self.dst_if.remote_ip4) /
+             UDP(sport=1234, dport=5678) /
+             Raw(payload))
+        fragments = fragment_rfc791(p, payload_len/4)
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[1])
+        self.pg_start()
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[0])
+        self.pg_start()
+        self.dst_if.get_capture(2)
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[2:])
+        self.pg_start()
+        self.dst_if.get_capture(len(fragments[2:]))
+
     def test_timeout(self):
         """ reassembly timeout """
         payload_len = 1000
@@ -1073,6 +1124,21 @@ class TestIPv6Reassembly(VppTestCase):
         self.src_if.assert_nothing_captured()
         self.dst_if.assert_nothing_captured()
 
+    def test_verify_clear_trace_mid_reassembly(self):
+        """ verify clear trace works mid-reassembly """
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(self.fragments_400[0:-1])
+        self.pg_start()
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.src_if.add_stream(self.fragments_400[-1])
+        self.pg_start()
+        packets = self.dst_if.get_capture(len(self.pkt_infos))
+        self.verify_capture(packets)
+
     def test_reversed(self):
         """ reverse order reassembly """
 
@@ -1635,6 +1701,41 @@ class TestIPv6SVReassembly(VppTestCase):
             self.assertEqual(sent[IPv6].dst, recvd[IPv6].dst)
             self.assertEqual(sent[Raw].payload, recvd[Raw].payload)
 
+    def test_verify_clear_trace_mid_reassembly(self):
+        """ verify clear trace works mid-reassembly """
+        payload_len = 1000
+        payload = ""
+        counter = 0
+        while len(payload) < payload_len:
+            payload += "%u " % counter
+            counter += 1
+
+        p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) /
+             IPv6(src=self.src_if.remote_ip6, dst=self.dst_if.remote_ip6) /
+             UDP(sport=1234, dport=5678) /
+             Raw(payload))
+        fragments = fragment_rfc8200(p, 1, payload_len/4)
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[1])
+        self.pg_start()
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[0])
+        self.pg_start()
+        self.dst_if.get_capture(2)
+
+        self.logger.debug(self.vapi.cli("show trace"))
+        self.vapi.cli("clear trace")
+
+        self.pg_enable_capture()
+        self.src_if.add_stream(fragments[2:])
+        self.pg_start()
+        self.dst_if.get_capture(len(fragments[2:]))
+
     def test_timeout(self):
         """ reassembly timeout """
         payload_len = 1000