Class: Toaster::SyscallTracer

Inherits:
Object
  • Object
show all
Defined in:
lib/toaster/state/syscall_tracer.rb

Constant Summary collapse

FILE_DUMPSTATE = 
"/tmp/tracer.dumpstate"
FILE_STATEDUMP = 
"/tmp/tracer.state.dump"
FILE_TMPDIR = 
"/tmp/tracer.tmp.dir"
FILE_ACKS = 
"/tmp/tracer.acks"

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SyscallTracer

Returns a new instance of SyscallTracer.



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# File 'lib/toaster/state/syscall_tracer.rb', line 22

def initialize()
  # type 0 syscalls (see below for parsing)
  @syscalls_0 = ["open", "write", "openat"]
  # type 1 syscalls (see below for parsing)
  @syscalls_1 = ["creat", "mkdir", "rmdir", "link", "unlink", "symlink", 
    "chown", "lchown", "chmod"]
  # type 2 syscalls (see below for parsing)
  @syscalls_2 = ["rename", "unlinkat", "mkdirat", "fchownat", "mknodat"]
  # type 3 syscalls (see below for parsing)
  @syscalls_3 = ["fchmod", "fchown"]
  # type 4 syscalls (see below for parsing)
  @syscalls_4 = ["utimensat"]
  @acked_syscalls = @syscalls_0.concat(@syscalls_1).concat(@syscalls_2).concat(@syscalls_3).concat(@syscalls_4)
  @monitored_syscalls = @acked_syscalls.dup.concat(["open", "openat", "chdir"]) #, "close", "dup", "dup2", "dup3"
  @grep_cmd = "ps aux | grep -v grep | grep -v bash | grep -v screen | grep -v SCREEN | grep strace | grep #{Process.pid}"
  @pwd_map = {}
  @num_acks_sent = 0
  @num_acks_received = 0
  @execution_prestate = {"files"=>{}}
end

Instance Method Details

#dump_execution_prestate ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 43

def dump_execution_prestate
  Util.write(FILE_DUMPSTATE, "1", true)

  # HACK: this causes a syscall which initiates the dump further below..
  Dir.mkdir(FILE_TMPDIR)
  Dir.rmdir(FILE_TMPDIR)

  state = File.read(FILE_STATEDUMP)
  if state.strip == ""
    puts "WARN: could not read pre-state dump from #{FILE_STATEDUMP}"
    return {}
  else
    return MarkupUtil.parse_json(state)
  end
end

#extract_pid(line) ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 178

def extract_pid(line)
  line.gsub(/^(\[pid\s+)?([0-9]+)\]?\s+([a-zA-Z0-2]+)\(.*/, '\2').strip
end

#extract_syscall(line) ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 175

def extract_syscall(line)
  line.gsub(/^(\[pid\s+)?[0-9]+\]?\s+([a-zA-Z0-2]+)\(.*/, '\2').strip
end

#is_correct_strace_line(line) ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 172

def is_correct_strace_line(line)
  line.match(/^(\[pid\s+)?[0-9]+\]?\s+[a-zA-Z0-2]+\(.*/)
end

#parse_line(line) ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 92

def parse_line(line)
  pwd_map = @pwd_map
  if is_correct_strace_line(line)

    syscall = extract_syscall(line)
    syscall_pid = extract_pid(line)
    if !pwd_map[syscall_pid]
      # get initial pwd for the process which does the syscall
      pwd_map[syscall_pid] = get_pwd_for_pid(syscall_pid)
    end
    pwd = pwd_map[syscall_pid]
    if syscall == "chdir"
      pwd = pwd_map[syscall_pid] = get_pwd_for_pid(syscall_pid)
    elsif syscall == "write"
      if line.match(/.*write\([0-9]+<(.*)>.*/)
        mod_file = line.gsub(/.*write\([0-9]+<(.*)>.*/, '\1').strip
        return report_file(mod_file, pwd)
      elsif line.match(/.*write\([0-9]+,.*/)
        fd = line.gsub(/.*write\(([0-9]+),.*/, '\1').strip
        mod_file = PtraceUtil.get_filename_for_fd(syscall_pid, fd)
        return report_file(mod_file, pwd)
      end
    elsif syscall == "open" || syscall == "openat"
      if  line.match(/O_WRONLY/) ||
          line.match(/O_RDWR/) ||
          line.match(/O_APPEND/) ||
          line.match(/O_CREAT/)
        if syscall == "open"
          mod_file = line.gsub(/.*open\("([^"]+)".*/, '\1').strip
          return report_file(mod_file, pwd)
        elsif syscall == "openat"
          if line.match(/.*openat\(AT_FDCWD,\s*"([^"]+)".*/)
            mod_file = line.gsub(/.*openat\(AT_FDCWD,\s*"([^"]+)".*/, '\1').strip
            return report_file(mod_file, pwd)
          elsif line.match(/.*openat\([0-9]+,\s*"([^"]+)".*/)
            fd = line.gsub(/.*openat\(([0-9]+),\s*"[^"]+".*/, '\1').strip.to_i
            mod_file = PtraceUtil.get_filename_for_fd(syscall_pid, fd)
            return report_file(mod_file, pwd)
          elsif line.match(/.*openat\("([^"]+)",\s*"[^"]+".*/)
            mod_file = line.gsub(/.*openat\("([^"]+)",\s*"[^"]+".*/, '\1').strip
            return report_file(mod_file, pwd)
          end
        end
      end
    else

      if @syscalls_1.include?(syscall)
        mod_file = line.gsub(/.*((#{@syscalls_1.join(')|(')}))\("([^"]+)".*/, "\\#{@syscalls_1.size + 2}").strip
        return report_file(mod_file, pwd)
      end
      if @syscalls_2.include?(syscall)
        mod_file = line.gsub(/.*((#{@syscalls_2.join(')|(')}))\([^,]+,\s*"([^"]+)".*/, "\\#{@syscalls_2.size + 2}").strip
        return report_file(mod_file, pwd)
      end
      if @syscalls_3.include?(syscall)
        fd = line.gsub(/.*((#{@syscalls_3.join(')|(')}))\(([^,]+),.*/, "\\#{@syscalls_3.size + 2}").strip.to_i
        mod_file = PtraceUtil.get_filename_for_fd(syscall_pid, fd)
        #puts "!! syscalls_3: #{mod_file}"
        return report_file(mod_file, pwd)
      end
      if @syscalls_4.include?(syscall)
        mod_file = nil
        pattern1 = ".*((#{@syscalls_4.join(')|(')}))\\(([0-9]+),.*"
        pattern2 = ".*((#{@syscalls_4.join(')|(')}))\\([^,]+,\\s*\"([^\"]+)\".*"
        if line.match(/#{pattern1}/)
          fd = line.gsub(/#{pattern1}/, "\\#{@syscalls_4.size + 2}").strip.to_i
          mod_file = PtraceUtil.get_filename_for_fd(syscall_pid, fd)
        elsif line.match(/#{pattern2}/)
          mod_file = line.gsub(/#{pattern2}/, "\\#{@syscalls_4.size + 2}")
        end
        #puts "!! syscalls_3: #{mod_file}"
        return report_file(mod_file, pwd)
      end

    end

  end
  return nil
end

#report_file(mod_file, pwd) ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 182

def report_file(mod_file, pwd)
  if !mod_file || mod_file.to_s.strip == ""
    return
  end
  if  !mod_file.match(/pipe:.*/) && 
      !mod_file.match(/socket:.*/) && 
      !mod_file.match(/\/dev\/.*/) &&
      !mod_file.match(/\/proc\/.*/) && 
      !mod_file.match(/\/tmp\/chef-script.*/) && 
      !mod_file.match(/\/var\/chef\/cache\/.*/) && 
      !mod_file.match(/\/tmp\/tracer\.acks.*/)
    if is_correct_strace_line(mod_file)
      puts "WARN: Apparently could not parse syscall line from strace: #{mod_file}"
      return
    end
    #puts "=====> #{pwd} - #{mod_file}"
    if mod_file[0] != "/" && pwd != ""
      mod_file = "#{pwd}/#{mod_file}"
    end
    # ignore /tmp files
    if !mod_file.match(/^\/tmp\//)
      return mod_file
    end
    return nil
  end
end

#start ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 59

def start()

  #puts "INFO: writing values to #{FILE_ACKS}"
  `echo ":#{@acked_syscalls.join(':')}:" > #{FILE_ACKS}`
  @monitoring_active = true

  `echo "" > #{FILE_DUMPSTATE}`
  `echo "" > #{FILE_STATEDUMP}`

  # start strace process
  do_start_process = true
  do_start_thread = false

  if do_start_process

    tracer_pid = start_strace()

    if do_start_thread
      __legacy_start_thread()
    end

  else
    __legacy_ruby_ptrace()
  end

end

#stop ⇒ Object 



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# File 'lib/toaster/state/syscall_tracer.rb', line 86

def stop()
  puts "DEBUG: writing empty string to #{FILE_ACKS}"
  `echo "" > #{FILE_ACKS}`
  @monitoring_active = false
end