checkprocfs.go

// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Tetragon

package checkprocfs

import (
	"path/filepath"
	"syscall"

	"github.com/cilium/tetragon/pkg/logger"
	"github.com/cilium/tetragon/pkg/option"
	"github.com/sirupsen/logrus"
)

// Check tries to determine whether the configured procfs is the host's procfs
func Check() {

	path := filepath.Join(option.Config.ProcFS, "1", "ns", "pid")
	var stat syscall.Stat_t
	if err := syscall.Stat(path, &stat); err != nil {
		logger.GetLogger().WithField("path", path).WithError(err).Info("stat failed")
	}

	// we compare against the known inode of the host pid namespace:
	// ...
	// 	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
	// ...
	expectedIno := uint64(0xEFFFFFFC)
	if stat.Ino != expectedIno {
		logger.GetLogger().WithFields(logrus.Fields{
			"path":           path,
			"inode":          stat.Ino,
			"expected inode": expectedIno,
		}).Warn("inode mismatch: procfs does not appear to be host procfs")
	}
}