whatcanGOwrong

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/examples/uretprobe/bpf_bpfel_x86.go

@@ -0,0 +1,124 @@
+// Code generated by bpf2go; DO NOT EDIT.
+//go:build 386 || amd64
+
+package main
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"io"
+
+	"github.com/cilium/ebpf"
+)
+
+type bpfEvent struct {
+	Pid  uint32
+	Line [80]uint8
+}
+
+// loadBpf returns the embedded CollectionSpec for bpf.
+func loadBpf() (*ebpf.CollectionSpec, error) {
+	reader := bytes.NewReader(_BpfBytes)
+	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("can't load bpf: %w", err)
+	}
+
+	return spec, err
+}
+
+// loadBpfObjects loads bpf and converts it into a struct.
+//
+// The following types are suitable as obj argument:
+//
+//	*bpfObjects
+//	*bpfPrograms
+//	*bpfMaps
+//
+// See ebpf.CollectionSpec.LoadAndAssign documentation for details.
+func loadBpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
+	spec, err := loadBpf()
+	if err != nil {
+		return err
+	}
+
+	return spec.LoadAndAssign(obj, opts)
+}
+
+// bpfSpecs contains maps and programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfSpecs struct {
+	bpfProgramSpecs
+	bpfMapSpecs
+}
+
+// bpfSpecs contains programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfProgramSpecs struct {
+	UretprobeBashReadline *ebpf.ProgramSpec `ebpf:"uretprobe_bash_readline"`
+}
+
+// bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfMapSpecs struct {
+	Events *ebpf.MapSpec `ebpf:"events"`
+}
+
+// bpfObjects contains all objects after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfObjects struct {
+	bpfPrograms
+	bpfMaps
+}
+
+func (o *bpfObjects) Close() error {
+	return _BpfClose(
+		&o.bpfPrograms,
+		&o.bpfMaps,
+	)
+}
+
+// bpfMaps contains all maps after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfMaps struct {
+	Events *ebpf.Map `ebpf:"events"`
+}
+
+func (m *bpfMaps) Close() error {
+	return _BpfClose(
+		m.Events,
+	)
+}
+
+// bpfPrograms contains all programs after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfPrograms struct {
+	UretprobeBashReadline *ebpf.Program `ebpf:"uretprobe_bash_readline"`
+}
+
+func (p *bpfPrograms) Close() error {
+	return _BpfClose(
+		p.UretprobeBashReadline,
+	)
+}
+
+func _BpfClose(closers ...io.Closer) error {
+	for _, closer := range closers {
+		if err := closer.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Do not access this directly.
+//
+//go:embed bpf_bpfel_x86.o
+var _BpfBytes []byte

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/examples/uretprobe/main.go

@@ -0,0 +1,113 @@
+// This program demonstrates how to attach an eBPF program to a uretprobe.
+// The program will be attached to the 'readline' symbol in the binary '/bin/bash' and print out
+// the line which 'readline' functions returns to the caller.
+
+//go:build amd64
+
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/cilium/ebpf/link"
+	"github.com/cilium/ebpf/perf"
+	"github.com/cilium/ebpf/rlimit"
+	"golang.org/x/sys/unix"
+)
+
+// $BPF_CLANG and $BPF_CFLAGS are set by the Makefile.
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc $BPF_CLANG -cflags $BPF_CFLAGS -target amd64 -type event bpf uretprobe.c -- -I../headers
+
+const (
+	// The path to the ELF binary containing the function to trace.
+	// On some distributions, the 'readline' function is provided by a
+	// dynamically-linked library, so the path of the library will need
+	// to be specified instead, e.g. /usr/lib/libreadline.so.8.
+	// Use `ldd /bin/bash` to find these paths.
+	binPath = "/bin/bash"
+	symbol  = "readline"
+)
+
+func main() {
+	stopper := make(chan os.Signal, 1)
+	signal.Notify(stopper, os.Interrupt, syscall.SIGTERM)
+
+	// Allow the current process to lock memory for eBPF resources.
+	if err := rlimit.RemoveMemlock(); err != nil {
+		log.Fatal(err)
+	}
+
+	// Load pre-compiled programs and maps into the kernel.
+	objs := bpfObjects{}
+	if err := loadBpfObjects(&objs, nil); err != nil {
+		log.Fatalf("loading objects: %s", err)
+	}
+	defer objs.Close()
+
+	// Open an ELF binary and read its symbols.
+	ex, err := link.OpenExecutable(binPath)
+	if err != nil {
+		log.Fatalf("opening executable: %s", err)
+	}
+
+	// Open a Uretprobe at the exit point of the symbol and attach
+	// the pre-compiled eBPF program to it.
+	up, err := ex.Uretprobe(symbol, objs.UretprobeBashReadline, nil)
+	if err != nil {
+		log.Fatalf("creating uretprobe: %s", err)
+	}
+	defer up.Close()
+
+	// Open a perf event reader from userspace on the PERF_EVENT_ARRAY map
+	// described in the eBPF C program.
+	rd, err := perf.NewReader(objs.Events, os.Getpagesize())
+	if err != nil {
+		log.Fatalf("creating perf event reader: %s", err)
+	}
+	defer rd.Close()
+
+	go func() {
+		// Wait for a signal and close the perf reader,
+		// which will interrupt rd.Read() and make the program exit.
+		<-stopper
+		log.Println("Received signal, exiting program..")
+
+		if err := rd.Close(); err != nil {
+			log.Fatalf("closing perf event reader: %s", err)
+		}
+	}()
+
+	log.Printf("Listening for events..")
+
+	// bpfEvent is generated by bpf2go.
+	var event bpfEvent
+	for {
+		record, err := rd.Read()
+		if err != nil {
+			if errors.Is(err, perf.ErrClosed) {
+				return
+			}
+			log.Printf("reading from perf event reader: %s", err)
+			continue
+		}
+
+		if record.LostSamples != 0 {
+			log.Printf("perf event ring buffer full, dropped %d samples", record.LostSamples)
+			continue
+		}
+
+		// Parse the perf event entry into a bpfEvent structure.
+		if err := binary.Read(bytes.NewBuffer(record.RawSample), binary.LittleEndian, &event); err != nil {
+			log.Printf("parsing perf event: %s", err)
+			continue
+		}
+
+		log.Printf("%s:%s return value: %s", binPath, symbol, unix.ByteSliceToString(event.Line[:]))
+	}
+}

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/examples/uretprobe/uretprobe.c

@@ -0,0 +1,31 @@
+//go:build ignore
+
+#include "common.h"
+
+#include "bpf_tracing.h"
+
+char __license[] SEC("license") = "Dual MIT/GPL";
+
+struct event {
+	u32 pid;
+	u8 line[80];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+} events SEC(".maps");
+
+// Force emitting struct event into the ELF.
+const struct event *unused __attribute__((unused));
+
+SEC("uretprobe/bash_readline")
+int uretprobe_bash_readline(struct pt_regs *ctx) {
+	struct event event;
+
+	event.pid = bpf_get_current_pid_tgid();
+	bpf_probe_read(&event.line, sizeof(event.line), (void *)PT_REGS_RC(ctx));
+
+	bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &event, sizeof(event));
+
+	return 0;
+}