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// Copyright 2017 Louis McCormack
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"encoding/binary"
"fmt"
"os"
"os/signal"
bpf "github.com/iovisor/gobpf/bcc"
)
const source string = `
#include <uapi/linux/ptrace.h>
struct readline_event_t {
u32 pid;
char str[80];
} __attribute__((packed));
BPF_PERF_OUTPUT(readline_events);
int get_return_value(struct pt_regs *ctx) {
struct readline_event_t event = {};
u32 pid;
if (!PT_REGS_RC(ctx))
return 0;
pid = bpf_get_current_pid_tgid();
event.pid = pid;
bpf_probe_read(&event.str, sizeof(event.str), (void *)PT_REGS_RC(ctx));
readline_events.perf_submit(ctx, &event, sizeof(event));
return 0;
}
`
type readlineEvent struct {
Pid uint32
Str [80]byte
}
func main() {
m := bpf.NewModule(source, []string{})
defer m.Close()
readlineUretprobe, err := m.LoadUprobe("get_return_value")
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to load get_return_value: %s\n", err)
os.Exit(1)
}
err = m.AttachUretprobe("/bin/bash", "readline", readlineUretprobe, -1)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to attach return_value: %s\n", err)
os.Exit(1)
}
table := bpf.NewTable(m.TableId("readline_events"), m)
channel := make(chan []byte)
perfMap, err := bpf.InitPerfMap(table, channel, nil)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to init perf map: %s\n", err)
os.Exit(1)
}
sig := make(chan os.Signal, 1)
signal.Notify(sig, os.Interrupt, os.Kill)
fmt.Printf("%10s\t%s\n", "PID", "COMMAND")
go func() {
var event readlineEvent
for {
data := <-channel
err := binary.Read(bytes.NewBuffer(data), binary.LittleEndian, &event)
if err != nil {
fmt.Printf("failed to decode received data: %s\n", err)
continue
}
// Convert C string (null-terminated) to Go string
comm := string(event.Str[:bytes.IndexByte(event.Str[:], 0)])
fmt.Printf("%10d\t%s\n", event.Pid, comm)
}
}()
perfMap.Start()
<-sig
perfMap.Stop()
}
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