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110d93ab25
On Windows, Nomad uses `syscall.NewLazyDLL` and `syscall.LoadDLL` functions to load a few system DLL files, which does not prevent DLL hijacking attacks. Hypothetically a local attacker on the client host that can place an abusive library in a specific location could use this to escalate privileges to the Nomad process. Although this attack does not fall within the Nomad security model, it doesn't hurt to follow good practices here. We can remove two of these DLL loads by using wrapper functions provided by the stdlib in `x/sys/windows` Co-authored-by: dduzgun-security <deniz.duzgun@hashicorp.com>
68 lines
1.9 KiB
Go
68 lines
1.9 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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//go:build windows
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package executor
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import (
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"fmt"
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"os"
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"syscall"
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"golang.org/x/sys/windows"
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)
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// configure new process group for child process
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func (e *UniversalExecutor) setNewProcessGroup() error {
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// We need to check that as build flags includes windows for this file
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if e.childCmd.SysProcAttr == nil {
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e.childCmd.SysProcAttr = &syscall.SysProcAttr{}
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}
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e.childCmd.SysProcAttr.CreationFlags = syscall.CREATE_NEW_PROCESS_GROUP
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return nil
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}
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// Cleanup any still hanging user processes
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func (e *UniversalExecutor) killProcessTree(proc *os.Process) error {
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// We must first verify if the process is still running.
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// (Windows process often lingered around after being reported as killed).
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handle, err := syscall.OpenProcess(syscall.PROCESS_TERMINATE|syscall.SYNCHRONIZE|syscall.PROCESS_QUERY_INFORMATION, false, uint32(proc.Pid))
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if err != nil {
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return os.NewSyscallError("OpenProcess", err)
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}
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defer syscall.CloseHandle(handle)
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result, err := syscall.WaitForSingleObject(syscall.Handle(handle), 0)
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switch result {
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case syscall.WAIT_OBJECT_0:
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return nil
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case syscall.WAIT_TIMEOUT:
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// Process still running. Just kill it.
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return proc.Kill()
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default:
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return os.NewSyscallError("WaitForSingleObject", err)
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}
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}
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// Send a Ctrl-Break signal for shutting down the process,
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func sendCtrlBreak(pid int) error {
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err := windows.GenerateConsoleCtrlEvent(syscall.CTRL_BREAK_EVENT, uint32(pid))
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if err != nil {
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return fmt.Errorf("Error sending ctrl-break event: %v", err)
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}
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return nil
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}
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// Send the process a Ctrl-Break event, allowing it to shutdown by itself
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// before being Terminate.
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func (e *UniversalExecutor) shutdownProcess(_ os.Signal, proc *os.Process) error {
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if err := sendCtrlBreak(proc.Pid); err != nil {
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return fmt.Errorf("executor shutdown error: %v", err)
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}
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e.logger.Debug("sent Ctrl-Break to process", "pid", proc.Pid)
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return nil
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}
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