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contained.go
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contained.go
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// Copyright 2023-2024 The Parca Authors
// 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 contained
import (
"embed"
"encoding/binary"
"fmt"
"io"
"os"
"runtime"
libbpf "github.com/aquasecurity/libbpfgo"
"github.com/aquasecurity/libbpfgo/helpers"
"github.com/go-kit/log"
"go.uber.org/atomic"
parcalogger "github.com/parca-dev/parca-agent/pkg/logger"
)
//go:embed bpf/*
var bpfObjects embed.FS
const (
maxEvents = 25
pollIntervalMs = 50
binaryPath = "/proc/self/exe"
symbolName = "github.com/parca-dev/parca-agent/pkg/contained.testFunction"
)
//go:noinline
func testFunction() {
fmt.Fprintf(io.Discard, "Side-effect to avoid the compiler to optimize it out.")
}
func IsRootPIDNamespace(logger log.Logger) (bool, error) {
libbpf.SetLoggerCbs(parcalogger.NewLibbpfLogCallbacks(logger))
f, err := bpfObjects.Open(fmt.Sprintf("bpf/%s/pid_namespace.bpf.o", runtime.GOARCH))
if err != nil {
return false, fmt.Errorf("failed to open BPF object: %w", err)
}
defer f.Close()
bpfObj, err := io.ReadAll(f)
if err != nil {
return false, fmt.Errorf("failed to read BPF object: %w", err)
}
bpfModule, err := libbpf.NewModuleFromBufferArgs(libbpf.NewModuleArgs{
BPFObjBuff: bpfObj,
BPFObjName: "pid-namespace",
})
if err != nil {
return false, fmt.Errorf("new bpf module: %w", err)
}
err = bpfModule.BPFLoadObject()
if err != nil {
return false, fmt.Errorf("new bpf module: %w", err)
}
prog, err := bpfModule.GetProgram("uprobe__test_function")
if err != nil {
return false, fmt.Errorf("failed to get program: %w", err)
}
offset, err := helpers.SymbolToOffset(binaryPath, symbolName)
if err != nil {
return false, fmt.Errorf("failed to compute function offset: %w", err)
}
_, err = prog.AttachUprobe(-1, binaryPath, offset)
if err != nil {
return false, fmt.Errorf("failed to attach uprobe: %w", err)
}
eventsChannel := make(chan []byte)
lostChannel := make(chan uint64)
perfBuf, err := bpfModule.InitPerfBuf("events", eventsChannel, lostChannel, 64)
if err != nil {
return false, fmt.Errorf("failed to init perf buffer: %w", err)
}
defer perfBuf.Stop()
defer perfBuf.Close()
perfBuf.Poll(int(pollIntervalMs))
var shouldRun atomic.Bool
shouldRun.Store(true)
defer func() {
shouldRun.Store(false)
}()
go func() {
for {
if !shouldRun.Load() {
break
}
testFunction()
}
}()
for i := 0; i < maxEvents; i++ {
b := <-eventsChannel
val := int(binary.LittleEndian.Uint32(b))
if val == os.Getpid() {
return true, nil
}
}
return false, nil
}