libbpf: Added AttachXDP wrapper (#170)

* libbpf: Added AttachXDP wrapper

* Added new link type XDP

* selftest: xdp: Added selftest

libbpfgo.go

@@ -238,6 +238,7 @@ const (
 	Uprobe
 	Uretprobe
 	Tracing
+	XDP
 )
 
 type BPFLink struct {
@@ -1277,6 +1278,26 @@ func (p *BPFProg) SetAttachType(attachType BPFAttachType) {
 	C.bpf_program__set_expected_attach_type(p.prog, C.enum_bpf_attach_type(int(attachType)))
 }
 
+func (p *BPFProg) AttachXDP(deviceName string) (*BPFLink, error) {
+	iface, err := net.InterfaceByName(deviceName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to find device by name %s: %w", deviceName, err)
+	}
+	link := C.bpf_program__attach_xdp(p.prog, C.int(iface.Index))
+	if C.IS_ERR_OR_NULL(unsafe.Pointer(link)) {
+		return nil, errptrError(unsafe.Pointer(link), "failed to attach xdp on device %s to program %s", deviceName, p.name)
+	}
+
+	bpfLink := &BPFLink{
+		link:      link,
+		prog:      p,
+		linkType:  XDP,
+		eventName: fmt.Sprintf("xdp-%s-%s", p.name, deviceName),
+	}
+	p.module.links = append(p.module.links, bpfLink)
+	return bpfLink, nil
+}
+
 func (p *BPFProg) AttachTracepoint(category, name string) (*BPFLink, error) {
 	tpCategory := C.CString(category)
 	tpName := C.CString(name)

selftest/xdp/Makefile

@@ -0,0 +1,91 @@
+BASEDIR = $(abspath ../../)
+
+OUTPUT = ../../output
+
+LIBBPF_SRC = $(abspath ../../libbpf/src)
+LIBBPF_OBJ = $(abspath $(OUTPUT)/libbpf.a)
+
+CC = gcc
+CLANG = clang
+GO = go
+
+ARCH := $(shell uname -m | sed 's/x86_64/amd64/g; s/aarch64/arm64/g')
+
+CFLAGS = -g -O2 -Wall -fpie
+LDFLAGS =
+
+CGO_CFLAGS_STATIC = "-I$(abspath $(OUTPUT))"
+CGO_LDFLAGS_STATIC = "-lelf -lz $(LIBBPF_OBJ)"
+CGO_EXTLDFLAGS_STATIC = '-w -extldflags "-static"'
+
+CGO_CFGLAGS_DYN = "-I. -I/usr/include/"
+CGO_LDFLAGS_DYN = "-lelf -lz -lbpf"
+
+.PHONY: $(TEST)
+.PHONY: $(TEST).go
+.PHONY: $(TEST).bpf.c
+
+TEST = main
+
+all: $(TEST)-static
+
+.PHONY: libbpfgo
+.PHONY: libbpfgo-static
+.PHONY: libbpfgo-dynamic
+
+## libbpfgo
+
+libbpfgo-static:
+	$(MAKE) -C $(BASEDIR) libbpfgo-static
+
+libbpfgo-dynamic:
+	$(MAKE) -C $(BASEDIR) libbpfgo-dynamic
+
+vmlinuxh:
+	$(MAKE) -C $(BASEDIR) vmlinuxh
+
+outputdir:
+	$(MAKE) -C $(BASEDIR) outputdir
+
+## test bpf dependency
+
+$(TEST).bpf.o: $(TEST).bpf.c
+	$(MAKE) -C $(BASEDIR) vmlinuxh
+	$(CLANG) $(CFLAGS) -target bpf -D__TARGET_ARCH_$(ARCH) -I$(OUTPUT) -c $< -o $@
+
+## test
+
+.PHONY: $(TEST)-static
+.PHONY: $(TEST)-dynamic
+
+$(TEST)-static: libbpfgo-static | $(TEST).bpf.o
+	CC=$(CLANG) \
+		CGO_CFLAGS=$(CGO_CFLAGS_STATIC) \
+		CGO_LDFLAGS=$(CGO_LDFLAGS_STATIC) \
+		GOOS=linux GOARCH=$(ARCH) \
+		$(GO) build \
+		-tags netgo -ldflags $(CGO_EXTLDFLAGS_STATIC) \
+		-o $(TEST)-static ./$(TEST).go
+
+$(TEST)-dynamic: libbpfgo-dynamic | $(TEST).bpf.o
+	CC=$(CLANG) \
+		CGO_CFLAGS=$(CGO_CFLAGS_DYN) \
+		CGO_LDFLAGS=$(CGO_LDFLAGS_DYN) \
+		$(GO) build -o ./$(TEST)-dynamic ./$(TEST).go
+
+## run
+
+.PHONY: run
+.PHONY: run-static
+.PHONY: run-dynamic
+
+run: run-static
+
+run-static: $(TEST)-static
+	sudo ./run.sh $(TEST)-static
+
+run-dynamic: $(TEST)-dynamic
+	sudo ./run.sh $(TEST)-dynamic
+
+clean:
+	rm -f *.o *-static *-dynamic

selftest/xdp/go.mod

@@ -0,0 +1,7 @@
+module github.com/aquasecurity/libbpfgo/selftest/perfbuffers
+
+go 1.16
+
+require github.com/aquasecurity/libbpfgo v0.2.1-libbpf-0.4.0
+
+replace github.com/aquasecurity/libbpfgo => ../../

selftest/xdp/go.sum

@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20210514084401-e8d321eab015/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

selftest/xdp/main.bpf.c

@@ -0,0 +1,33 @@
+//+build ignore
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#ifdef asm_inline
+#undef asm_inline
+#define asm_inline asm
+#endif
+
+struct {
+    __uint(type, BPF_MAP_TYPE_RINGBUF);
+    __uint(max_entries, 1 << 24);
+} events SEC(".maps");
+long ringbuffer_flags = 0;
+
+SEC("xdp")
+int target(struct xdp_md *ctx) {
+    int *process;
+
+    // Reserve space on the ringbuffer for the sample
+    process = bpf_ringbuf_reserve(&events, sizeof(int), ringbuffer_flags);
+    if (!process) {
+        return 0;
+    }
+
+    *process = 2021;
+
+    bpf_ringbuf_submit(process, ringbuffer_flags);
+    return XDP_PASS;
+}
+
+char LICENSE[] SEC("license") = "GPL";

selftest/xdp/main.go

@@ -0,0 +1,78 @@
+package main
+
+import "C"
+
+import (
+	"encoding/binary"
+	"fmt"
+	"os"
+	"os/exec"
+
+	bpf "github.com/aquasecurity/libbpfgo"
+)
+
+const (
+	deviceName = "lo"
+)
+
+func main() {
+
+	bpfModule, err := bpf.NewModuleFromFile("main.bpf.o")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(-1)
+	}
+	defer bpfModule.Close()
+
+	err = bpfModule.BPFLoadObject()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(-1)
+	}
+
+	xdpProg, err := bpfModule.GetProgram("target")
+	if xdpProg == nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(-1)
+	}
+
+	_, err = xdpProg.AttachXDP(deviceName)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(-1)
+	}
+
+	eventsChannel := make(chan []byte)
+	rb, err := bpfModule.InitRingBuf("events", eventsChannel)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(-1)
+	}
+
+	rb.Start()
+	numberOfEventsReceived := 0
+	go func() {
+		_, err := exec.Command("ping", "localhost", "-c 10").Output()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(-1)
+		}
+	}()
+
+recvLoop:
+
+	for {
+		b := <-eventsChannel
+		if binary.LittleEndian.Uint32(b) != 2021 {
+			fmt.Fprintf(os.Stderr, "invalid data retrieved\n")
+			os.Exit(-1)
+		}
+		numberOfEventsReceived++
+		if numberOfEventsReceived > 5 {
+			break recvLoop
+		}
+	}
+
+	rb.Stop()
+	rb.Close()
+}

selftest/xdp/run.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# SETTINGS
+
+TEST=$(dirname $0)/$1	# execute
+TIMEOUT=5			# seconds
+
+# COMMON
+
+COMMON="$(dirname $0)/../common/common.sh"
+[[ -f $COMMON ]] && { . $COMMON; } || { error "no common"; exit 1; }
+
+# MAIN
+
+kern_version ge 5.8
+
+check_build
+check_ppid
+test_exec
+test_finish
+
+exit 0