Class: SeccompTools::CLI::Emu

Inherits:
Base
  • Object
show all
Defined in:
lib/seccomp-tools/cli/emu.rb

Overview

Handle 'emu' command.

Constant Summary collapse

SUMMARY =

Summary of this command.

'Emulate seccomp rules.'
USAGE =

Usage of this command.

"emu - #{SUMMARY}\n\nUsage: seccomp-tools emu [options] BPF_FILE [sys_nr [arg0 [arg1 ... arg5]]]".freeze

Instance Attribute Summary

Attributes inherited from Base

#argv, #option

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Emu

Instantiate an SeccompTools::CLI::Emu object, defaulting to verbose output.

Takes the same arguments as Base#initialize.



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# File 'lib/seccomp-tools/cli/emu.rb', line 23

def initialize(*)
  super
  option[:verbose] = 1
end

Instance Method Details

#handle ⇒ void

This method returns an undefined value.

Emulates the filter against the given syscall and shows the resulting action.



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# File 'lib/seccomp-tools/cli/emu.rb', line 49

def handle
  return unless super

  option[:ifile] = argv.shift
  return CLI.show(parser.help) if option[:ifile].nil?

  raw = input
  insts = SeccompTools::Disasm.to_bpf(raw, option[:arch]).map(&:inst)
  sys, *args = argv
  sys = evaluate_sys_nr(sys) if sys
  args.map! { |v| Integer(v) }
  trace = Set.new
  res = SeccompTools::Emulator.new(
    insts,
    sys_nr: sys,
    args:,
    instruction_pointer: option[:instruction_pointer] && Integer(option[:instruction_pointer]),
    arch: option[:arch]
  ).run

  if option[:verbose] >= 1
    disasm = SeccompTools::Disasm.disasm(raw, arch: option[:arch]).lines
    output_emulate_path(disasm, trace, res)
  end
  output do
    ret_type = Const::BPF::ACTION.invert[res[:ret] & Const::BPF::SECCOMP_RET_ACTION_FULL]
    errno = ret_type == :ERRNO ? "(#{res[:ret] & Const::BPF::SECCOMP_RET_DATA})" : ''
    format("return %s%s at line %04d\n", ret_type, errno, res[:pc])
  end
end

#parser ⇒ OptionParser

Define option parser.

Returns:

  • (OptionParser) —

    The parser of this command's options.



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# File 'lib/seccomp-tools/cli/emu.rb', line 31

def parser
  @parser ||= OptionParser.new do |opt|
    opt.banner = usage

    option_arch(opt)

    opt.on('-q', '--[no-]quiet', 'Run quietly, only show emulation result.') do |v|
      option[:verbose] = 0 if v
    end

    opt.on('-i', '--ip=VAL', Integer, 'Set instruction pointer.') do |val|
      option[:instruction_pointer] = val
    end
  end
end