fix(ebpf): prevent file descriptor leak in resource retrieval

Signed-off-by: Shivansh Sahu <sahushivansh142@gmail.com>

Author: shivansh-gohem

pkg/utils/ebpf.go

@@ -34,23 +34,23 @@ func GetProgramByName(name string) (*ebpf.Program, error) {
 
 	for {
 		if progID, err = ebpf.ProgramGetNextID(progID); err != nil {
-			err = fmt.Errorf("failed to get system next program id, err is %v\n", err)
-			return nil, err
+			return nil, fmt.Errorf("failed to get system next program id: %w", err)
 		}
 
 		if targetProg, err = ebpf.NewProgramFromID(progID); err != nil {
-			err = fmt.Errorf("failed to get new program from id:%v, err is %v\n", progID, err)
-			return nil, err
+			return nil, fmt.Errorf("failed to get new program from id:%v: %w", progID, err)
 		}
 
 		if targetProgInfo, err = targetProg.Info(); err != nil {
-			err = fmt.Errorf("failed to get new program info from fd:%v, err is %v\n", targetProg, err)
-			return nil, err
+			targetProg.Close()
+			return nil, fmt.Errorf("failed to get new program info from fd:%v: %w", targetProg, err)
 		}
 
 		if strings.Compare(targetProgInfo.Name, name) == 0 {
 			return targetProg, nil
 		}
+
+		targetProg.Close()
 	}
 }
 
@@ -66,22 +66,22 @@ func GetMapByName(name string) (*ebpf.Map, error) {
 
 	for {
 		if mapID, err = ebpf.MapGetNextID(mapID); err != nil {
-			err = fmt.Errorf("failed to get system next map id, err is %v\n", err)
-			return nil, err
+			return nil, fmt.Errorf("failed to get system next map id: %w", err)
 		}
 
 		if targetMap, err = ebpf.NewMapFromID(mapID); err != nil {
-			err = fmt.Errorf("failed to get new map from id:%v, err is %v\n", mapID, err)
-			return nil, err
+			return nil, fmt.Errorf("failed to get new map from id:%v: %w", mapID, err)
 		}
 
 		if targetMapInfo, err = targetMap.Info(); err != nil {
-			err = fmt.Errorf("failed to get new map info from fd:%v, err is %v\n", targetMap, err)
-			return nil, err
+			targetMap.Close()
+			return nil, fmt.Errorf("failed to get new map info from fd:%v: %w", targetMap, err)
 		}
 
 		if strings.Compare(targetMapInfo.Name, name) == 0 {
 			return targetMap, nil
 		}
+
+		targetMap.Close()
 	}
 }

pkg/utils/ebpf_test.go

@@ -0,0 +1,68 @@
+//go:build linux
+// +build linux
+
+package utils
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+// countOpenFDs returns the number of open file descriptors for the current process.
+// It returns an error if /proc is not available (e.g., non-Linux environments).
+func countOpenFDs(t *testing.T) int {
+	t.Helper()
+	pid := os.Getpid()
+	fds, err := os.ReadDir(fmt.Sprintf("/proc/%d/fd", pid))
+	if err != nil {
+		t.Fatalf("failed to read /proc/%d/fd: %v", pid, err)
+	}
+	return len(fds)
+}
+
+func TestGetProgramByName_FDLeak(t *testing.T) {
+	initialFDs := countOpenFDs(t)
+	t.Logf("Initial open File Descriptors: %d", initialFDs)
+
+	// Call the function in a loop.
+	// Searching for a non-existent program forces it to iterate through ALL
+	// loaded BPF programs, which would previously leak an FD for every single one.
+	for i := 0; i < 100; i++ {
+		_, err := GetProgramByName("non_existent_fake_prog_12345")
+		if err == nil {
+			t.Fatal("expected error for non-existent program, got nil")
+		}
+	}
+
+	finalFDs := countOpenFDs(t)
+	t.Logf("Final open File Descriptors: %d", finalFDs)
+
+	if finalFDs > initialFDs+10 {
+		t.Fatalf("FD LEAK DETECTED! Started with %d FDs, ended with %d FDs.", initialFDs, finalFDs)
+	}
+	t.Log("No leak detected.")
+}
+
+func TestGetMapByName_FDLeak(t *testing.T) {
+	initialFDs := countOpenFDs(t)
+	t.Logf("Initial open File Descriptors: %d", initialFDs)
+
+	// Call the function in a loop.
+	// Searching for a non-existent map forces it to iterate through ALL
+	// loaded BPF maps, which would previously leak an FD for every single one.
+	for i := 0; i < 100; i++ {
+		_, err := GetMapByName("non_existent_fake_map_12345")
+		if err == nil {
+			t.Fatal("expected error for non-existent map, got nil")
+		}
+	}
+
+	finalFDs := countOpenFDs(t)
+	t.Logf("Final open File Descriptors: %d", finalFDs)
+
+	if finalFDs > initialFDs+10 {
+		t.Fatalf("FD LEAK DETECTED! Started with %d FDs, ended with %d FDs.", initialFDs, finalFDs)
+	}
+	t.Log("No leak detected.")
+}