Class: GSSAPI::Simple

Inherits:
Object
  • Object
show all
Defined in:
lib/gssapi/simple.rb

Overview

This class is a simple wrapper around the most common usage of GSSAPI. If you are looking at doing

something a bit more advanced you may want to check out the LibGSSAPI module.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(host_name, service_name = nil, keytab = nil) ⇒ Simple

Initialize a new GSSAPI::Simple object

Parameters:

  • host_name (String) —

    the fully qualified host name

  • service_name (String) (defaults to: nil) —

    The service name. This can either be a GSS_KRB5_NT_PRINCIPAL_NAME in the form of srvc/fqdn@REALM or GSS_C_NT_HOSTBASED_SERVICE in the form of srvc@fqdn If there is no ‘@fqdn’ part, the host_name will be appended. If no service_name is given at all the default service of ‘host@fqdn’ will be used.



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# File 'lib/gssapi/simple.rb', line 22

def initialize(host_name, service_name=nil, keytab=nil)
  @host = host_name
  @service = service_name.nil? ? "host@#{@host}" : (service_name.include?('@') ? service_name : "#{service_name}@#{@host}")
  @int_svc_name = import_name(@service)
  @context = nil # the security context
  @scred = nil # the service credentials.  really only used for the server-side via acquire_credentials
  set_keytab(keytab) unless keytab.nil?
end

Instance Attribute Details

#context ⇒ Object (readonly)

Returns the value of attribute context.



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# File 'lib/gssapi/simple.rb', line 12

def context
  @context
end

Instance Method Details

#accept_context(in_token) ⇒ String, true

Accept a security context that was initiated by a remote peer.

Parameters:

  • in_token (String) —

    The token sent by the remote client to initiate the context

Returns:

  • (String, true) —

    If this is part of a continuation it will return a token to be passed back to the remote otherwise it will simply return true.

Raises:



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# File 'lib/gssapi/simple.rb', line 104

def accept_context(in_token)
  raise GssApiError, "No credentials yet acquired. Call #{self.class.name}#acquire_credentials first" if @scred.nil?

  min_stat = FFI::MemoryPointer.new :OM_uint32
  ctx = (@context.nil? ? LibGSSAPI::GssCtxIdT.gss_c_no_context.address_of : @context.address_of)
  no_chn_bind = LibGSSAPI::GSS_C_NO_CHANNEL_BINDINGS
  client = FFI::MemoryPointer.new :pointer  # Will hold the initiating client name after the call
  mech = FFI::MemoryPointer.new :pointer  # Will hold the mech being used after the call
  in_tok = GSSAPI::LibGSSAPI::UnManagedGssBufferDesc.new
  in_tok.value = in_token
  out_tok = GSSAPI::LibGSSAPI::ManagedGssBufferDesc.new
  ret_flags = FFI::MemoryPointer.new :OM_uint32

  maj_stat = LibGSSAPI.gss_accept_sec_context(min_stat,
                                              ctx,
                                              @scred,
                                              in_tok.pointer,
                                              no_chn_bind,
                                              client,
                                              mech,
                                              out_tok.pointer,
                                              ret_flags,
                                              nil, nil)

  raise GssApiError.new(maj_stat, min_stat), "gss_accept_sec_context did not return GSS_S_COMPLETE" if maj_stat > 1

  @context = LibGSSAPI::GssCtxIdT.new(ctx.get_pointer(0))
  out_tok.length > 0 ? out_tok.value : true
end

#acquire_credentials(princ = @int_svc_name, opts = {:usage => :accept}) ⇒ true

Acquire security credentials. This does not log you in. It grabs the credentials from a cred cache or keytab.

Parameters:

  • opts (Hash) (defaults to: {:usage => :accept}) —

    options to pass to the gss_acquire_cred function.

Options Hash (opts):

  • :usage (String) —

    The credential usage type (:accept, :initiate, :both). It defaults to ‘accept’ since this method is most usually called on the server only.

Returns:

  • (true) —

    It will return true if everything succeeds and the @scred variable will be set for future methods. If an error ocurrs an exception will be raised.

Raises:



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# File 'lib/gssapi/simple.rb', line 141

def acquire_credentials(princ = @int_svc_name, opts = {:usage => :accept})
  min_stat = FFI::MemoryPointer.new :OM_uint32
  scred = FFI::MemoryPointer.new :pointer

  case opts[:usage]
  when :accept
    usage = LibGSSAPI::GSS_C_ACCEPT
  when :initiate
    usage = LibGSSAPI::GSS_C_INITIATE
  when :both
    usage = LibGSSAPI::GSS_C_BOTH
  else
    raise GssApiError, "Bad option passed to #{self.class.name}#acquire_credentials"
  end

  maj_stat = LibGSSAPI.gss_acquire_cred(min_stat, princ, 0, LibGSSAPI::GSS_C_NO_OID_SET, usage, scred, nil, nil)
  raise GssApiError.new(maj_stat, min_stat), "gss_acquire_cred did not return GSS_S_COMPLETE" if maj_stat != 0

  @scred = LibGSSAPI::GssCredIdT.new(scred.get_pointer(0))
  true
end

#import_name(str) ⇒ Object

Convert a String to a GSSAPI usable buffer (gss_buffer_desc)

Parameters:

  • str (String) —

    the string to convert

Raises:



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# File 'lib/gssapi/simple.rb', line 34

def import_name(str)
  buff_str = LibGSSAPI::UnManagedGssBufferDesc.new
  buff_str.value = str
  # Choose the appropriate mechanism based on the string passed.
  if (str =~ /[A-Za-z0-9]+\/[^@]+@.+$/)
    mech = LibGSSAPI::GssOID.gss_c_no_oid
  else
    mech = LibGSSAPI::GSS_C_NT_HOSTBASED_SERVICE
  end
  name = FFI::MemoryPointer.new :pointer # gss_name_t
  min_stat = FFI::MemoryPointer.new :OM_uint32

  maj_stat = LibGSSAPI.gss_import_name(min_stat, buff_str.pointer, mech, name)
  raise GssApiError.new(maj_stat, min_stat), "gss_import_name did not return GSS_S_COMPLETE" if maj_stat != 0

  LibGSSAPI::GssNameT.new(name.get_pointer(0))
end

#init_context(in_token = nil, opts = {}) ⇒ String, true

Initialize the GSS security context (client initiator). If there was a previous call that issued a

continue you can pass the continuation token in via the token param.
If no flags are set the default flags are LibGSSAPI::GSS_C_MUTUAL_FLAG | LibGSSAPI::GSS_C_SEQUENCE_FLAG

Parameters:

  • in_token (String) (defaults to: nil) —

    an input token sent from the remote service in a continuation.

  • opts (Hash) (defaults to: {}) —

    misc opts to be set

Options Hash (opts):

  • :flags (Fixnum) —

    override all other flags. If you set the :delegate option this option will override it. @see tools.ietf.org/html/rfc4121#section-4.1.1.1

  • :delegate (Boolean) —

    if true set the credential delegate flag

Returns:

  • (String, true) —

    if a continuation flag is set it will return the output token that is needed to send to the remote host. Otherwise it returns true and the GSS security context has been established.

Raises:



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# File 'lib/gssapi/simple.rb', line 62

def init_context(in_token = nil, opts = {})
  min_stat = FFI::MemoryPointer.new :OM_uint32
  ctx = (@context.nil? ? LibGSSAPI::GssCtxIdT.gss_c_no_context.address_of : @context.address_of)
  mech = LibGSSAPI::GssOID.gss_c_no_oid
  if(opts[:flags])
    flags = opts[:flags]
  else
    flags = (LibGSSAPI::GSS_C_MUTUAL_FLAG | LibGSSAPI::GSS_C_SEQUENCE_FLAG | LibGSSAPI::GSS_C_CONF_FLAG | LibGSSAPI::GSS_C_INTEG_FLAG)
    flags |= LibGSSAPI::GSS_C_DELEG_FLAG  if opts[:delegate]
    flags |= LibGSSAPI::GSS_C_DELEG_POLICY_FLAG  if opts[:delegate]
  end
  in_tok = LibGSSAPI::UnManagedGssBufferDesc.new
  in_tok.value = in_token
  out_tok = LibGSSAPI::ManagedGssBufferDesc.new
  ret_flags = FFI::MemoryPointer.new :OM_uint32


  maj_stat = LibGSSAPI.gss_init_sec_context(min_stat,
                                            nil,
                                            ctx,
                                            @int_svc_name,
                                            mech,
                                            flags,
                                            0,
                                            nil,
                                            in_tok.pointer,
                                            nil,
                                            out_tok.pointer,
                                            ret_flags,
                                            nil)

  raise GssApiError.new(maj_stat, min_stat), "gss_init_sec_context did not return GSS_S_COMPLETE" if maj_stat > 1
  
  @context = LibGSSAPI::GssCtxIdT.new(ctx.get_pointer(0))
  maj_stat == 1 ? out_tok.value : true
end

#set_keytab(keytab) ⇒ Object

Add a path to a custom keytab file

Parameters:

  • keytab (String) —

    the path to the keytab

Raises:



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# File 'lib/gssapi/simple.rb', line 199

def set_keytab(keytab)
  maj_stat = LibGSSAPI.krb5_gss_register_acceptor_identity(keytab)
  raise GssApiError.new(maj_stat, min_stat), "krb5_gss_register_acceptor_identity did not return GSS_S_COMPLETE" if maj_stat != 0
  true
end

#unwrap_message(msg, encrypted = true) ⇒ Object

Unwrap a message previously wrapped with gss_wrap.

Parameters:

  • msg (String) —

    The message to unwrap

  • encrypted (Boolean) (defaults to: true) —

    Whether or not this message was encrypted (true) or just signed (false)

Raises:



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# File 'lib/gssapi/simple.rb', line 183

def unwrap_message(msg, encrypted = true)
  min_stat = FFI::MemoryPointer.new :OM_uint32
  in_buff = GSSAPI::LibGSSAPI::UnManagedGssBufferDesc.new
  in_buff.value = msg
  out_buff = GSSAPI::LibGSSAPI::ManagedGssBufferDesc.new
  conf_state = FFI::MemoryPointer.new :int
  conf_state.write_int((encrypted ? 1 : 0))
  q_op = FFI::MemoryPointer.new :OM_uint32
  q_op.write_int(0)
  maj_stat = GSSAPI::LibGSSAPI.gss_unwrap(min_stat, @context, in_buff.pointer, out_buff.pointer, conf_state, q_op)
  raise GssApiError.new(maj_stat, min_stat), "Failed to gss_unwrap message" if maj_stat != 0
  out_buff.value
end

#wrap_message(msg, encrypt = true) ⇒ String

Wrap a message using gss_wrap. It can either encrypt the message (confidentiality) or simply sign it (integrity).

Parameters:

  • msg (String) —

    The message to wrap

  • encrypt (Boolean) (defaults to: true) —

    Whether or not to encrypt the message or just sign it. The default is to encrypt.

Returns:

  • (String) —

    The wrapped message. It will raise an exception on error

Raises:



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# File 'lib/gssapi/simple.rb', line 167

def wrap_message(msg, encrypt = true)
  min_stat = FFI::MemoryPointer.new :OM_uint32
  conf_req = (encrypt ? 1 : 0)
  qop_req = GSSAPI::LibGSSAPI::GSS_C_QOP_DEFAULT
  in_buff = GSSAPI::LibGSSAPI::UnManagedGssBufferDesc.new
  in_buff.value = msg
  conf_state = FFI::MemoryPointer.new :OM_uint32
  out_buff = GSSAPI::LibGSSAPI::ManagedGssBufferDesc.new
  maj_stat = GSSAPI::LibGSSAPI.gss_wrap(min_stat, @context, conf_req, qop_req, in_buff.pointer, conf_state, out_buff.pointer)
  raise GssApiError.new(maj_stat, min_stat), "Failed to gss_wrap message" if maj_stat != 0
  out_buff.value
end