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authorAlexander Chernavin <achernavin@netgate.com>2023-11-07 11:25:21 +0000
committerMatthew Smith <mgsmith@netgate.com>2023-11-12 21:52:13 +0000
commit64d6463d2eac0c0fe434f3a7aa56fe4d85c046d9 (patch)
tree89871a62760cb89dfb37993fcf5b6d825cb6d0eb /src/plugins
parent4aaedaa2ffaf0cee9ceae62c785f940b6fe23535 (diff)
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 <achernavin@netgate.com>
Diffstat (limited to 'src/plugins')
-rw-r--r--src/plugins/flowprobe/node.c12
1 files changed, 7 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;