Merge pull request #656 from eyakubovich/add-map-setters

Add Resize() and GetMaxEntries() to BPFMap

libbpfgo/libbpfgo.go

@@ -366,6 +366,33 @@ func (b *BPFMap) SetPinPath(pinPath string) error {
 	return nil
 }
 
+// Resize changes the map's capacity to maxEntries.
+// It should be called after the module was initialized but
+// prior to it being loaded with BPFLoadObject.
+// Note: for ring buffer and perf buffer, maxEntries is the
+// capacity in bytes.
+func (b *BPFMap) Resize(maxEntries uint32) error {
+	cs := C.CString(b.name)
+	bpfMap := C.bpf_object__find_map_by_name(b.module.obj, cs)
+	errC := C.bpf_map__resize(bpfMap, C.uint(maxEntries))
+	C.free(unsafe.Pointer(cs))
+	if errC != 0 {
+		return fmt.Errorf("failed to resize map %s to %v", b.name, maxEntries)
+	}
+	return nil
+}
+
+// GetMaxEntries returns the map's capacity.
+// Note: for ring buffer and perf buffer, maxEntries is the
+// capacity in bytes.
+func (b *BPFMap) GetMaxEntries() uint32 {
+	cs := C.CString(b.name)
+	bpfMap := C.bpf_object__find_map_by_name(b.module.obj, cs)
+	maxEntries := C.bpf_map__max_entries(bpfMap)
+	C.free(unsafe.Pointer(cs))
+	return uint32(maxEntries)
+}
+
 func GetUnsafePointer(data interface{}) (unsafe.Pointer, error) {
 	var dataPtr unsafe.Pointer
 	if k, isType := data.(int8); isType {

libbpfgo/selftest/perfbuffers/main.go

@@ -11,6 +11,23 @@ import (
 	bpf "github.com/aquasecurity/tracee/libbpfgo"
 )
 
+func resizeMap(module *bpf.Module, name string, size uint32) error {
+	m, err := module.GetMap("events")
+	if err != nil {
+		return err
+	}
+
+	if err = m.Resize(size); err != nil {
+		return err
+	}
+
+	if actual := m.GetMaxEntries(); actual != size {
+		return fmt.Errorf("map resize failed, expected %v, actual %v", size, actual)
+	}
+
+	return nil
+}
+
 func main() {
 
 	bpfModule, err := bpf.NewModuleFromFile("self.bpf.o")
@@ -19,6 +36,10 @@ func main() {
 	}
 	defer bpfModule.Close()
 
+	if err = resizeMap(bpfModule, "events", 8192); err != nil {
+		os.Exit(-1)
+	}
+
 	bpfModule.BPFLoadObject()
 	prog, err := bpfModule.GetProgram("kprobe__sys_mmap")
 	if err != nil {

libbpfgo/selftest/ringbuffers/Makefile

@@ -7,7 +7,7 @@ BPF_SRC := $(shell find . -type f -name '*.bpf.c')
 PWD := $(shell pwd)
 
 LIBBPF_HEADERS := /usr/include/bpf
-LIBBPF_OBJ := /usr/lib64/libbpf.a
+LIBBPF_OBJ := -lbpf
 
 .PHONY: all
 all: vmlinux.h $(TARGET) $(TARGET_BPF)

libbpfgo/selftest/ringbuffers/main.go

@@ -11,6 +11,23 @@ import (
 	bpf "github.com/aquasecurity/tracee/libbpfgo"
 )
 
+func resizeMap(module *bpf.Module, name string, size uint32) error {
+	m, err := module.GetMap("events")
+	if err != nil {
+		return err
+	}
+
+	if err = m.Resize(size); err != nil {
+		return err
+	}
+
+	if actual := m.GetMaxEntries(); actual != size {
+		return fmt.Errorf("map resize failed, expected %v, actual %v", size, actual)
+	}
+
+	return nil
+}
+
 func main() {
 
 	bpfModule, err := bpf.NewModuleFromFile("self.bpf.o")
@@ -19,6 +36,10 @@ func main() {
 	}
 	defer bpfModule.Close()
 
+	if err = resizeMap(bpfModule, "events", 8192); err != nil {
+		os.Exit(-1)
+	}
+
 	bpfModule.BPFLoadObject()
 	prog, err := bpfModule.GetProgram("kprobe__sys_mmap")
 	if err != nil {