From da5ddd1714859bfffbb471569e87a7ddd72ac78b Mon Sep 17 00:00:00 2001 From: Alexander Chernavin Date: Tue, 7 Nov 2023 11:25:21 +0000 Subject: flowprobe: fix tx flows generated for rewritten traffic Currently, when IPFIX records generation is enabled for an interface in the TX direction, some rewritten traffic is being sent from that interface, and the Ethernet header's location has changed due to rewriting, generated TX flows will contain fields with wrong and zero values. For example, that can be observed when traffic is rewritten from a subinterface to a hardware interface (i.e. when tags are removed). A TX flow generated in this case will have wrong L2 fields because of an incorrectly located Ethernet header. And zero L3/L4 fields because the Ethernet type will match neither IP4 nor IP6. The same code is executed to generate flows for both input and output features. And the same mechanism is applied to identify the Ethernet header in the buffer's data. However, such general code usually works with the buffer's data conditionally based on the direction. For most input features, the buffer's current_data will likely point to the IP header. For most output features, the buffer's current_data will likely point to the Ethernet header. With this fix: - Keep relying on ethernet_buffer_get_header() to locate the Ethernet header for input features. And start using vlib_buffer_get_current() to locate the Ethernet header for output features. The function will account for the Ethernet header's position change in the buffer's data if there is rewriting. - After fixing Ethernet header determination in the buffer's data, L3/L4 fields will contain non-zero but still incorrect data. That is because IP header determination needs to be fixed too. It currently relies on the fact that the Ethernet header is always located at the beginning of the buffer's data and that l2_hdr_sz can be used as an IP header offset. However, this may not be the case after rewriting. So start calculating the actual offset of the IP header in the buffer's data. - Add a unit test to cover the case. Type: fix Change-Id: Icf3f9e6518912d06dff0d5aa48e103b3dc94edb7 Signed-off-by: Alexander Chernavin (cherry picked from commit 64d6463d2eac0c0fe434f3a7aa56fe4d85c046d9) --- src/plugins/flowprobe/node.c | 12 ++++--- test/test_flowprobe.py | 75 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+), 5 deletions(-) diff --git a/src/plugins/flowprobe/node.c b/src/plugins/flowprobe/node.c index 274ea388ccd..22bb6cea80a 100644 --- a/src/plugins/flowprobe/node.c +++ b/src/plugins/flowprobe/node.c @@ -384,9 +384,11 @@ add_to_flow_record_state (vlib_main_t *vm, vlib_node_runtime_t *node, flowprobe_record_t flags = fm->context[which].flags; bool collect_ip4 = false, collect_ip6 = false; ASSERT (b); - ethernet_header_t *eth = ethernet_buffer_get_header (b); + ethernet_header_t *eth = (direction == FLOW_DIRECTION_TX) ? + vlib_buffer_get_current (b) : + ethernet_buffer_get_header (b); u16 ethertype = clib_net_to_host_u16 (eth->type); - u16 l2_hdr_sz = sizeof (ethernet_header_t); + u16 l3_hdr_offset = (u8 *) eth - b->data + sizeof (ethernet_header_t); /* *INDENT-OFF* */ flowprobe_key_t k = {}; /* *INDENT-ON* */ @@ -423,13 +425,13 @@ add_to_flow_record_state (vlib_main_t *vm, vlib_node_runtime_t *node, while (clib_net_to_host_u16 (ethv->type) == ETHERNET_TYPE_VLAN) { ethv++; - l2_hdr_sz += sizeof (ethernet_vlan_header_tv_t); + l3_hdr_offset += sizeof (ethernet_vlan_header_tv_t); } k.ethertype = ethertype = clib_net_to_host_u16 ((ethv)->type); } if (collect_ip6 && ethertype == ETHERNET_TYPE_IP6) { - ip6 = (ip6_header_t *) (b->data + l2_hdr_sz); + ip6 = (ip6_header_t *) (b->data + l3_hdr_offset); if (flags & FLOW_RECORD_L3) { k.src_address.as_u64[0] = ip6->src_address.as_u64[0]; @@ -448,7 +450,7 @@ add_to_flow_record_state (vlib_main_t *vm, vlib_node_runtime_t *node, } if (collect_ip4 && ethertype == ETHERNET_TYPE_IP4) { - ip4 = (ip4_header_t *) (b->data + l2_hdr_sz); + ip4 = (ip4_header_t *) (b->data + l3_hdr_offset); if (flags & FLOW_RECORD_L3) { k.src_address.ip4.as_u32 = ip4->src_address.as_u32; diff --git a/test/test_flowprobe.py b/test/test_flowprobe.py index 5cc36ad305a..0ad94990f1f 100644 --- a/test/test_flowprobe.py +++ b/test/test_flowprobe.py @@ -26,6 +26,7 @@ from vpp_ip_route import VppIpRoute, VppRoutePath from vpp_papi.macaddress import mac_ntop from socket import inet_ntop from vpp_papi import VppEnum +from vpp_sub_interface import VppDot1ADSubint TMPL_COMMON_FIELD_COUNT = 6 @@ -36,6 +37,9 @@ TMPL_L4_FIELD_COUNT = 3 IPFIX_TCP_FLAGS_ID = 6 IPFIX_SRC_TRANS_PORT_ID = 7 IPFIX_DST_TRANS_PORT_ID = 11 +IPFIX_SRC_IP4_ADDR_ID = 8 +IPFIX_DST_IP4_ADDR_ID = 12 +IPFIX_FLOW_DIRECTION_ID = 61 TCP_F_FIN = 0x01 TCP_F_SYN = 0x02 @@ -1226,6 +1230,77 @@ class DatapathTx(MethodHolder, DatapathTestsHolder): intf3 = "pg6" direction = "tx" + def test_rewritten_traffic(self): + """Rewritten traffic (from subif to ipfix if)""" + self.pg_enable_capture(self.pg_interfaces) + self.pkts = [] + + # prepare a sub-interface + subif = VppDot1ADSubint(self, self.pg7, 0, 300, 400) + subif.admin_up() + subif.config_ip4() + + # enable ip4 datapath for an interface + ipfix = VppCFLOW( + test=self, + intf="pg8", + datapath="ip4", + layer="l2 l3 l4", + direction=self.direction, + ) + ipfix.add_vpp_config() + + # template packet should arrive immediately + ipfix_decoder = IPFIXDecoder() + templates = ipfix.verify_templates(ipfix_decoder, count=1) + + # forward some traffic through the ipfix interface + route = VppIpRoute( + self, + "9.0.0.0", + 24, + [VppRoutePath(self.pg8.remote_ip4, self.pg8.sw_if_index)], + ) + route.add_vpp_config() + + # prepare an IPv4 packet (subif => ipfix interface) + pkt = ( + Ether(src=subif.remote_mac, dst=self.pg7.local_mac) + / IP(src=subif.remote_ip4, dst="9.0.0.1") + / UDP(sport=1234, dport=4321) + / Raw(b"\xa5" * 123) + ) + self.pkts = [ + subif.add_dot1ad_layer(pkt, 300, 400), + ] + + # send the packet + capture = self.send_packets(self.pg7, self.pg8) + + # wait for a flow and verify it + self.vapi.ipfix_flush() + cflow = self.wait_for_cflow_packet(self.collector, templates[0]) + self.verify_cflow_data(ipfix_decoder, capture, cflow) + self.verify_cflow_data_detail( + ipfix_decoder, + capture, + cflow, + { + IPFIX_SRC_IP4_ADDR_ID: "src_ip", + IPFIX_DST_IP4_ADDR_ID: "dst_ip", + IPFIX_SRC_TRANS_PORT_ID: "sport", + IPFIX_DST_TRANS_PORT_ID: "dport", + IPFIX_FLOW_DIRECTION_ID: (self.direction == "tx"), + }, + ) + + self.collector.get_capture(2) + + # cleanup + route.remove_vpp_config() + subif.remove_vpp_config() + ipfix.remove_vpp_config() + @tag_fixme_vpp_workers class DatapathRx(MethodHolder, DatapathTestsHolder): -- cgit 1.2.3-korg