Enhance bpf_query to show TracingLinkInfo fields

The enhanced TracingLinkInfo struct now includes target_obj_id and
target_btf_id fields that are directly available from the kernel's
bpf_link_info structure. This eliminates the need for additional
syscalls to retrieve BTF information for tracing links.

Example output:

    $ sudo ./target/debug/bpf_query link
    id=   6 prog_id=1437 type=tracing
        attach_type=LsmMac target_obj_id=1 target_btf_id=59022

This output correlates with bpftool:

    $ sudo bpftool link show id 6
    6: tracing  prog 1437
            prog_type lsm  attach_type lsm_mac
            target_obj_id 1  target_btf_id 59022

Signed-off-by: Andrew McDermott <[email protected]>

Author: frobware

examples/bpf_query/src/main.rs

@@ -101,6 +101,13 @@ fn link() {
             "id={:4} prog_id={:4} type={}",
             link.id, link.prog_id, link_type_str
         );
+
+        if let query::LinkTypeInfo::Tracing(ref tracing) = link.info {
+            println!(
+                "    attach_type={:?} target_obj_id={} target_btf_id={}",
+                tracing.attach_type, tracing.target_obj_id, tracing.target_btf_id
+            );
+        }
     }
 }
 

libbpf-rs/src/query.rs

@@ -623,7 +623,7 @@ pub struct RawTracepointLinkInfo {
 pub struct TracingLinkInfo {
     /// Attach type of the tracing link.
     pub attach_type: ProgramAttachType,
-    /// Target object ID (prog_id for PROG_EXT, otherwise btf object id).
+    /// Target object ID (`prog_id` for `PROG_EXT`, otherwise btf object id).
     pub target_obj_id: u32,
     /// BTF type id inside the target object.
     pub target_btf_id: u32,