Class: Bolt::Shell::Bash

Inherits:
Bolt::Shell show all
Defined in:
lib/bolt/shell/bash.rb,
lib/bolt/shell/bash/tmpdir.rb

Defined Under Namespace

Classes: Tmpdir

Constant Summary collapse

CHUNK_SIZE = 
4096

Instance Attribute Summary

Attributes inherited from Bolt::Shell

#conn, #logger, #target

Instance Method Summary collapse

Methods inherited from Bolt::Shell

#default_input_method, #envify_params, #select_implementation, #select_interpreter, #unwrap_sensitive_args

Constructor Details

#initialize(target, conn) ⇒ Bash

Returns a new instance of Bash.



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# File 'lib/bolt/shell/bash.rb', line 11

def initialize(target, conn)
  super

  @run_as = nil

  @sudo_id = SecureRandom.uuid
  @sudo_password = @target.options['sudo-password'] || @target.password
end

Instance Method Details

#build_sudoable_command_str(command_str, sudo_str, sudo_id, options) ⇒ Object

A helper to build up a single string that contains all of the options for privilege escalation. A wrapper script is used to direct task input to stdin when a tty is allocated and thus we do not need to prepend_sudo_success when using the wrapper or when the task does not require stdin data.



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# File 'lib/bolt/shell/bash.rb', line 297

def build_sudoable_command_str(command_str, sudo_str, sudo_id, options)
  if options[:stdin] && !options[:wrapper]
    "#{sudo_str} #{prepend_sudo_success(sudo_id, command_str)}"
  elsif conn.reset_cwd?
    "#{sudo_str} #{prepend_chdir(command_str)}"
  else
    "#{sudo_str} #{command_str}"
  end
end

#check_sudo(out, inp, stdin) ⇒ Object

See if there’s a sudo prompt in the output If not, return the output



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# File 'lib/bolt/shell/bash.rb', line 170

def check_sudo(out, inp, stdin)
  buffer = out.readpartial(CHUNK_SIZE)
  # Split on newlines, including the newline
  lines = buffer.split(/(?<=[\n])/)
  # handle_sudo will return the line if it is not a sudo prompt or error
  lines.map! { |line| handle_sudo(inp, line, stdin) }
  lines.join("")
# If stream has reached EOF, no password prompt is expected
# return an empty string
rescue EOFError
  ''
end

#execute(command, sudoable: false, **options) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 320

def execute(command, sudoable: false, **options)
  run_as = options[:run_as] || self.run_as
  escalate = sudoable && run_as && conn.user != run_as
  use_sudo = escalate && @target.options['run-as-command'].nil?

  command_str = inject_interpreter(options[:interpreter], command)

  if options[:environment]
    env_decls = options[:environment].map do |env, val|
      "#{env}=#{Shellwords.shellescape(val)}"
    end
    command_str = "#{env_decls.join(' ')} #{command_str}"
  end

  if escalate
    if use_sudo
      sudo_exec = target.options['sudo-executable'] || "sudo"
      sudo_flags = [sudo_exec, "-S", "-H", "-u", run_as, "-p", sudo_prompt]
      sudo_flags += ["-E"] if options[:environment]
      sudo_str = Shellwords.shelljoin(sudo_flags)
    else
      sudo_str = Shellwords.shelljoin(@target.options['run-as-command'] + [run_as])
    end
    command_str = build_sudoable_command_str(command_str, sudo_str, @sudo_id, options)
  end

  @logger.debug { "Executing: #{command_str}" }

  in_buffer = if !use_sudo && options[:stdin]
                String.new(options[:stdin], encoding: 'binary')
              else
                String.new(encoding: 'binary')
              end
  # Chunks of this size will be read in one iteration
  index = 0
  timeout = 0.1

  inp, out, err, t = conn.execute(command_str)
  result_output = Bolt::Node::Output.new
  read_streams = { out => String.new,
                   err => String.new }
  write_stream = in_buffer.empty? ? [] : [inp]

  # See if there's a sudo prompt
  if use_sudo
    ready_read = select([err], nil, nil, timeout * 5)
    read_streams[err] << check_sudo(err, inp, options[:stdin]) if ready_read
  end

  # True while the process is running or waiting for IO input
  while t.alive?
    # See if we can read from out or err, or write to in
    ready_read, ready_write, = select(read_streams.keys, write_stream, nil, timeout)

    # Read from out and err
    ready_read&.each do |stream|
      # Check for sudo prompt
      read_streams[stream] << if use_sudo
                                check_sudo(stream, inp, options[:stdin])
                              else
                                stream.readpartial(CHUNK_SIZE)
                              end
    rescue EOFError
    end

    # select will either return an empty array if there are no
    # writable streams or nil if no IO object is available before the
    # timeout is reached.
    writable = if ready_write.respond_to?(:empty?)
                 !ready_write.empty?
               else
                 !ready_write.nil?
               end

    begin
      if writable && index < in_buffer.length
        to_print = in_buffer[index..-1]
        # On Windows, select marks the input stream as writable even if
        # it's full. We need to check whether we received wait_writable
        # and treat that as not having written anything.
        written = inp.write_nonblock(to_print, exception: false)
        index += written unless written == :wait_writable

        if index >= in_buffer.length && !write_stream.empty?
          inp.close
          write_stream = []
        end
      end
    # If a task has stdin as an input_method but doesn't actually read
    # from stdin, the task may return and close the input stream before
    # we finish writing
    rescue Errno::EPIPE
      write_stream = []
    end
  end
  # Read any remaining data in the pipe. Do not wait for
  # EOF in case the pipe is inherited by a child process.
  read_streams.each do |stream, _|
    loop { read_streams[stream] << stream.read_nonblock(CHUNK_SIZE) }
  rescue Errno::EAGAIN, EOFError
  end
  result_output.stdout << read_streams[out]
  result_output.stderr << read_streams[err]
  result_output.exit_code = t.value.respond_to?(:exitstatus) ? t.value.exitstatus : t.value

  if result_output.exit_code == 0
    @logger.debug { "Command returned successfully" }
  else
    @logger.info { "Command failed with exit code #{result_output.exit_code}" }
  end
  result_output
rescue StandardError
  # Ensure we close stdin and kill the child process
  inp&.close
  t&.terminate if t&.alive?
  @logger.debug { "Command aborted" }
  raise
end

#handle_sudo(stdin, err, sudo_stdin) ⇒ Object

If prompted for sudo password, send password to stdin and return an empty string. Otherwise, check for sudo errors and raise Bolt error. If sudo_id is detected, that means the task needs to have stdin written. If error is not sudo-related, return the stderr string to be added to node output



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# File 'lib/bolt/shell/bash.rb', line 139

def handle_sudo(stdin, err, sudo_stdin)
  if err.include?(sudo_prompt)
    # A wild sudo prompt has appeared!
    if @sudo_password
      stdin.write("#{@sudo_password}\n")
      ''
    else
      raise Bolt::Node::EscalateError.new(
        "Sudo password for user #{conn.user} was not provided for #{target}",
        'NO_PASSWORD'
      )
    end
  elsif err =~ /^#{@sudo_id}/
    if sudo_stdin
      begin
        stdin.write("#{sudo_stdin}\n")
        stdin.close
      # If a task has stdin as an input_method but doesn't actually read
      # from stdin, the task may return and close the input stream before
      # we finish writing
      rescue Errno::EPIPE
      end
    end
    ''
  else
    handle_sudo_errors(err)
  end
end

#handle_sudo_errors(err) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 183

def handle_sudo_errors(err)
  if err =~ /^#{conn.user} is not in the sudoers file\./
    @logger.debug { err }
    raise Bolt::Node::EscalateError.new(
      "User #{conn.user} does not have sudo permission on #{target}",
      'SUDO_DENIED'
    )
  elsif err =~ /^Sorry, try again\./
    @logger.debug { err }
    raise Bolt::Node::EscalateError.new(
      "Sudo password for user #{conn.user} not recognized on #{target}",
      'BAD_PASSWORD'
    )
  else
    # No need to raise an error - just return the string
    err
  end
end

#inject_interpreter(interpreter, command) ⇒ Object

Returns string with the interpreter conditionally prepended



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# File 'lib/bolt/shell/bash.rb', line 308

def inject_interpreter(interpreter, command)
  if interpreter
    if command.is_a?(Array)
      command.unshift(interpreter)
    else
      command = [interpreter, command]
    end
  end

  command.is_a?(String) ? command : Shellwords.shelljoin(command)
end

#make_executable(path) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 235

def make_executable(path)
  result = execute(['chmod', 'u+x', path])
  if result.exit_code != 0
    message = "Could not make file '#{path}' executable: #{result.stderr.string}"
    raise Bolt::Node::FileError.new(message, 'CHMOD_ERROR')
  end
end

#make_tmpdir ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 243

def make_tmpdir
  tmpdir = @target.options.fetch('tmpdir', '/tmp')
  script_dir = @target.options.fetch('script-dir', SecureRandom.uuid)
  tmppath = File.join(tmpdir, script_dir)
  command = ['mkdir', '-m', 700, tmppath]

  result = execute(command)
  if result.exit_code != 0
    raise Bolt::Node::FileError.new("Could not make tmpdir: #{result.stderr.string}", 'TMPDIR_ERROR')
  end
  path = tmppath || result.stdout.string.chomp
  Bolt::Shell::Bash::Tmpdir.new(self, path)
end

#make_wrapper_stringio(task_path, stdin, interpreter = nil) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 202

def make_wrapper_stringio(task_path, stdin, interpreter = nil)
  if interpreter
    StringIO.new(<<~SCRIPT)
      #!/bin/sh
      '#{interpreter}' '#{task_path}' <<'EOF'
      #{stdin}
      EOF
    SCRIPT
  else
    StringIO.new(<<~SCRIPT)
      #!/bin/sh
      '#{task_path}' <<'EOF'
      #{stdin}
      EOF
    SCRIPT
  end
end

#prepend_chdir(command_str) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 289

def prepend_chdir(command_str)
  "sh -c #{Shellwords.shellescape("cd; #{command_str}")}"
end

#prepend_sudo_success(sudo_id, command_str) ⇒ Object

In the case where a task is run with elevated privilege and needs stdin a random string is echoed to stderr indicating that the stdin is available for task input data because the sudo password has already either been provided on stdin or was not needed.



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# File 'lib/bolt/shell/bash.rb', line 284

def prepend_sudo_success(sudo_id, command_str)
  command_str = "cd; #{command_str}" if conn.reset_cwd?
  "sh -c #{Shellwords.shellescape("echo #{sudo_id} 1>&2; #{command_str}")}"
end

#provided_features ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 20

def provided_features
  ['shell']
end

#run_as ⇒ Object

This method allows the @run_as variable to be used as a per-operation override for the user to run as. When @run_as is unset, the user specified on the target will be used.



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# File 'lib/bolt/shell/bash.rb', line 223

def run_as
  @run_as || target.options['run-as']
end

#run_command(command, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 24

def run_command(command, options = {})
  running_as(options[:run_as]) do
    output = execute(command, sudoable: true)
    Bolt::Result.for_command(target,
                             output.stdout.string,
                             output.stderr.string,
                             output.exit_code,
                             'command', command)
  end
end

#run_script(script, arguments, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 53

def run_script(script, arguments, options = {})
  # unpack any Sensitive data
  arguments = unwrap_sensitive_args(arguments)

  running_as(options[:run_as]) do
    with_tmpdir do |dir|
      path = write_executable(dir.to_s, script)
      dir.chown(run_as)
      output = execute([path, *arguments], sudoable: true)
      Bolt::Result.for_command(target,
                               output.stdout.string,
                               output.stderr.string,
                               output.exit_code,
                               'script', script)
    end
  end
end

#run_task(task, arguments, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 71

def run_task(task, arguments, options = {})
  implementation = select_implementation(target, task)
  executable = implementation['path']
  input_method = implementation['input_method']
  extra_files = implementation['files']

  running_as(options[:run_as]) do
    stdin, output = nil
    execute_options = {}
    execute_options[:interpreter] = select_interpreter(executable, target.options['interpreters'])
    interpreter_debug = if execute_options[:interpreter]
                          " using '#{execute_options[:interpreter]}' interpreter"
                        end
    # log the arguments with sensitive data redacted, do NOT log unwrapped_arguments
    logger.debug("Running '#{executable}' with #{arguments.to_json}#{interpreter_debug}")
    # unpack any Sensitive data
    arguments = unwrap_sensitive_args(arguments)

    with_tmpdir do |dir|
      if extra_files.empty?
        task_dir = dir
      else
        # TODO: optimize upload of directories
        arguments['_installdir'] = dir.to_s
        task_dir = File.join(dir.to_s, task.tasks_dir)
        dir.mkdirs([task.tasks_dir] + extra_files.map { |file| File.dirname(file['name']) })
        extra_files.each do |file|
          conn.copy_file(file['path'], File.join(dir.to_s, file['name']))
        end
      end

      if Bolt::Task::STDIN_METHODS.include?(input_method)
        stdin = JSON.dump(arguments)
      end

      if Bolt::Task::ENVIRONMENT_METHODS.include?(input_method)
        execute_options[:environment] = envify_params(arguments)
      end

      remote_task_path = write_executable(task_dir, executable)

      # Avoid the horrors of passing data on stdin via a tty on multiple platforms
      # by writing a wrapper script that directs stdin to the task.
      if stdin && target.options['tty']
        wrapper = make_wrapper_stringio(remote_task_path, stdin, execute_options[:interpreter])
        execute_options.delete(:interpreter)
        execute_options[:wrapper] = true
        remote_task_path = write_executable(dir, wrapper, 'wrapper.sh')
      end

      dir.chown(run_as)

      execute_options[:stdin] = stdin
      execute_options[:sudoable] = true if run_as
      output = execute(remote_task_path, execute_options)
    end
    Bolt::Result.for_task(target, output.stdout.string,
                          output.stderr.string,
                          output.exit_code,
                          task.name)
  end
end

#running_as(user) ⇒ Object

Run as the specified user for the duration of the block.



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# File 'lib/bolt/shell/bash.rb', line 228

def running_as(user)
  @run_as = user
  yield
ensure
  @run_as = nil
end

#sudo_prompt ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 439

def sudo_prompt
  '[sudo] Bolt needs to run as another user, password: '
end

#upload(source, destination, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 35

def upload(source, destination, options = {})
  running_as(options[:run_as]) do
    with_tmpdir do |dir|
      basename = File.basename(destination)
      tmpfile = File.join(dir.to_s, basename)
      conn.copy_file(source, tmpfile)
      # pass over file ownership if we're using run-as to be a different user
      dir.chown(run_as)
      result = execute(['mv', '-f', tmpfile, destination], sudoable: true)
      if result.exit_code != 0
        message = "Could not move temporary file '#{tmpfile}' to #{destination}: #{result.stderr.string}"
        raise Bolt::Node::FileError.new(message, 'MV_ERROR')
      end
    end
    Bolt::Result.for_upload(target, source, destination)
  end
end

#with_tmpdir ⇒ Object

A helper to create and delete a tmpdir on the remote system. Yields the directory name.



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# File 'lib/bolt/shell/bash.rb', line 267

def with_tmpdir
  dir = make_tmpdir
  yield dir
ensure
  if dir
    if target.options['cleanup']
      dir.delete
    else
      @logger.warn("Skipping cleanup of tmpdir #{dir}")
    end
  end
end

#write_executable(dir, file, filename = nil) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 257

def write_executable(dir, file, filename = nil)
  filename ||= File.basename(file)
  remote_path = File.join(dir.to_s, filename)
  conn.copy_file(file, remote_path)
  make_executable(remote_path)
  remote_path
end