require 'net/ssh/buffer'
require 'net/ssh/errors'
require 'net/ssh/loggable'
require 'net/ssh/transport/server_version'
require 'socket'
require 'rubygems'
require 'net/ssh/authentication/pageant' if Gem.win_platform? && RUBY_PLATFORM != "java"
module Net; module SSH; module Authentication
# Class for representing agent-specific errors.
class AgentError < Net::SSH::Exception; end
# An exception for indicating that the SSH agent is not available.
class AgentNotAvailable < AgentError; end
# This class implements a simple client for the ssh-agent protocol. It
# does not implement any specific protocol, but instead copies the
# behavior of the ssh-agent functions in the OpenSSH library (3.8).
#
# This means that although it behaves like a SSH1 client, it also has
# some SSH2 functionality (like signing data).
class Agent
include Loggable
# A simple module for extending keys, to allow comments to be specified
# for them.
module Comment
attr_accessor :comment
end
SSH2_AGENT_REQUEST_VERSION = 1
SSH2_AGENT_REQUEST_IDENTITIES = 11
SSH2_AGENT_IDENTITIES_ANSWER = 12
SSH2_AGENT_SIGN_REQUEST = 13
SSH2_AGENT_SIGN_RESPONSE = 14
SSH2_AGENT_ADD_IDENTITY = 17
SSH2_AGENT_REMOVE_IDENTITY = 18
SSH2_AGENT_REMOVE_ALL_IDENTITIES = 19
SSH2_AGENT_ADD_ID_CONSTRAINED = 25
SSH2_AGENT_FAILURE = 30
SSH2_AGENT_VERSION_RESPONSE = 103
SSH_COM_AGENT2_FAILURE = 102
SSH_AGENT_REQUEST_RSA_IDENTITIES = 1
SSH_AGENT_RSA_IDENTITIES_ANSWER1 = 2
SSH_AGENT_RSA_IDENTITIES_ANSWER2 = 5
SSH_AGENT_FAILURE = 5
SSH_AGENT_SUCCESS = 6
SSH_AGENT_CONSTRAIN_LIFETIME = 1
SSH_AGENT_CONSTRAIN_CONFIRM = 2
SSH_AGENT_RSA_SHA2_256 = 0x02
SSH_AGENT_RSA_SHA2_512 = 0x04
# The underlying socket being used to communicate with the SSH agent.
attr_reader :socket
# Instantiates a new agent object, connects to a running SSH agent,
# negotiates the agent protocol version, and returns the agent object.
def self.connect(logger=nil, agent_socket_factory = nil)
agent = new(logger)
agent.connect!(agent_socket_factory)
agent.negotiate!
agent
end
# Creates a new Agent object, using the optional logger instance to
# report status.
def initialize(logger=nil)
self.logger = logger
end
# Connect to the agent process using the socket factory and socket name
# given by the attribute writers. If the agent on the other end of the
# socket reports that it is an SSH2-compatible agent, this will fail
# (it only supports the ssh-agent distributed by OpenSSH).
def connect!(agent_socket_factory = nil)
debug { "connecting to ssh-agent" }
@socket =
if agent_socket_factory
agent_socket_factory.call
elsif ENV['SSH_AUTH_SOCK'] && unix_socket_class
unix_socket_class.open(ENV['SSH_AUTH_SOCK'])
elsif Gem.win_platform? && RUBY_ENGINE != "jruby"
Pageant::Socket.open
else
raise AgentNotAvailable, "Agent not configured"
end
rescue StandardError => e
error { "could not connect to ssh-agent: #{e.message}" }
raise AgentNotAvailable, $!.message
end
# Attempts to negotiate the SSH agent protocol version. Raises an error
# if the version could not be negotiated successfully.
def negotiate!
# determine what type of agent we're communicating with
type, body = send_and_wait(SSH2_AGENT_REQUEST_VERSION, :string, Transport::ServerVersion::PROTO_VERSION)
raise AgentNotAvailable, "SSH2 agents are not yet supported" if type == SSH2_AGENT_VERSION_RESPONSE
if type == SSH2_AGENT_FAILURE
debug { "Unexpected response type==#{type}, this will be ignored" }
elsif type != SSH_AGENT_RSA_IDENTITIES_ANSWER1 && type != SSH_AGENT_RSA_IDENTITIES_ANSWER2
raise AgentNotAvailable, "unknown response from agent: #{type}, #{body.to_s.inspect}"
end
end
# Return an array of all identities (public keys) known to the agent.
# Each key returned is augmented with a +comment+ property which is set
# to the comment returned by the agent for that key.
def identities
type, body = send_and_wait(SSH2_AGENT_REQUEST_IDENTITIES)
raise AgentError, "could not get identity count" if agent_failed(type)
raise AgentError, "bad authentication reply: #{type}" if type != SSH2_AGENT_IDENTITIES_ANSWER
identities = []
body.read_long.times do
key_str = body.read_string
comment_str = body.read_string
begin
key = Buffer.new(key_str).read_key
key.extend(Comment)
key.comment = comment_str
identities.push key
rescue NotImplementedError => e
error { "ignoring unimplemented key:#{e.message} #{comment_str}" }
end
end
return identities
end
# Closes this socket. This agent reference is no longer able to
# query the agent.
def close
@socket.close
end
# Using the agent and the given public key, sign the given data. The
# signature is returned in SSH2 format.
def sign(key, data, flags = 0)
type, reply = send_and_wait(SSH2_AGENT_SIGN_REQUEST, :string, Buffer.from(:key, key), :string, data, :long, flags)
raise AgentError, "agent could not sign data with requested identity" if agent_failed(type)
raise AgentError, "bad authentication response #{type}" if type != SSH2_AGENT_SIGN_RESPONSE
return reply.read_string
end
# Adds the private key with comment to the agent.
# If lifetime is given, the key will automatically be removed after lifetime
# seconds.
# If confirm is true, confirmation will be required for each agent signing
# operation.
def add_identity(priv_key, comment, lifetime: nil, confirm: false)
constraints = Buffer.new
if lifetime
constraints.write_byte(SSH_AGENT_CONSTRAIN_LIFETIME)
constraints.write_long(lifetime)
end
constraints.write_byte(SSH_AGENT_CONSTRAIN_CONFIRM) if confirm
req_type = constraints.empty? ? SSH2_AGENT_ADD_IDENTITY : SSH2_AGENT_ADD_ID_CONSTRAINED
type, = send_and_wait(req_type, :string, priv_key.ssh_type, :raw, blob_for_add(priv_key),
:string, comment, :raw, constraints)
raise AgentError, "could not add identity to agent" if type != SSH_AGENT_SUCCESS
end
# Removes key from the agent.
def remove_identity(key)
type, = send_and_wait(SSH2_AGENT_REMOVE_IDENTITY, :string, key.to_blob)
raise AgentError, "could not remove identity from agent" if type != SSH_AGENT_SUCCESS
end
# Removes all identities from the agent.
def remove_all_identities
type, = send_and_wait(SSH2_AGENT_REMOVE_ALL_IDENTITIES)
raise AgentError, "could not remove all identity from agent" if type != SSH_AGENT_SUCCESS
end
private
def unix_socket_class
defined?(UNIXSocket) && UNIXSocket
end
# Send a new packet of the given type, with the associated data.
def send_packet(type, *args)
buffer = Buffer.from(*args)
data = [buffer.length + 1, type.to_i, buffer.to_s].pack("NCA*")
debug { "sending agent request #{type} len #{buffer.length}" }
@socket.send data, 0
end
# Read the next packet from the agent. This will return a two-part
# tuple consisting of the packet type, and the packet's body (which
# is returned as a Net::SSH::Buffer).
def read_packet
buffer = Net::SSH::Buffer.new(@socket.read(4))
buffer.append(@socket.read(buffer.read_long))
type = buffer.read_byte
debug { "received agent packet #{type} len #{buffer.length-4}" }
return type, buffer
end
# Send the given packet and return the subsequent reply from the agent.
# (See #send_packet and #read_packet).
def send_and_wait(type, *args)
send_packet(type, *args)
read_packet
end
# Returns +true+ if the parameter indicates a "failure" response from
# the agent, and +false+ otherwise.
def agent_failed(type)
type == SSH_AGENT_FAILURE ||
type == SSH2_AGENT_FAILURE ||
type == SSH_COM_AGENT2_FAILURE
end
def blob_for_add(priv_key)
# Ideally we'd have something like `to_private_blob` on the various key types, but the
# nuances with encoding (e.g. `n` and `e` are reversed for RSA keys) make this impractical.
case priv_key.ssh_type
when /^ssh-dss$/
Net::SSH::Buffer.from(:bignum, priv_key.p, :bignum, priv_key.q, :bignum, priv_key.g,
:bignum, priv_key.pub_key, :bignum, priv_key.priv_key).to_s
when /^ssh-dss-cert-v01@openssh\.com$/
Net::SSH::Buffer.from(:string, priv_key.to_blob, :bignum, priv_key.key.priv_key).to_s
when /^ecdsa\-sha2\-(\w*)$/
curve_name = OpenSSL::PKey::EC::CurveNameAliasInv[priv_key.group.curve_name]
Net::SSH::Buffer.from(:string, curve_name, :mstring, priv_key.public_key.to_bn.to_s(2),
:bignum, priv_key.private_key).to_s
when /^ecdsa\-sha2\-(\w*)-cert-v01@openssh\.com$/
Net::SSH::Buffer.from(:string, priv_key.to_blob, :bignum, priv_key.key.private_key).to_s
when /^ssh-ed25519$/
Net::SSH::Buffer.from(:string, priv_key.public_key.verify_key.to_bytes,
:string, priv_key.sign_key.keypair).to_s
when /^ssh-ed25519-cert-v01@openssh\.com$/
# Unlike the other certificate types, the public key is included after the certifiate.
Net::SSH::Buffer.from(:string, priv_key.to_blob,
:string, priv_key.key.public_key.verify_key.to_bytes,
:string, priv_key.key.sign_key.keypair).to_s
when /^ssh-rsa$/
# `n` and `e` are reversed compared to the ordering in `OpenSSL::PKey::RSA#to_blob`.
Net::SSH::Buffer.from(:bignum, priv_key.n, :bignum, priv_key.e, :bignum, priv_key.d,
:bignum, priv_key.iqmp, :bignum, priv_key.p, :bignum, priv_key.q).to_s
when /^ssh-rsa-cert-v01@openssh\.com$/
Net::SSH::Buffer.from(:string, priv_key.to_blob, :bignum, priv_key.key.d,
:bignum, priv_key.key.iqmp, :bignum, priv_key.key.p,
:bignum, priv_key.key.q).to_s
end
end
end
end; end; end