Host resource: use bash over netcat in Linux (#2607)

* Add support to use bash in host resource

Netcat's presence is widely regarded as a security issue, and thus not
always available. This solution first tries to use bash builtins and
timeout (from coreutils), so is less likely to require installing
additional packages.

* Darwin UDP support in host resource
* Host: use netcat first if available

Signed-off-by: João Vale <jpvale@gmail.com>
This commit is contained in:
João Vale 2018-03-07 13:39:27 +00:00 committed by Jared Quick
parent 0994c63d48
commit 3e2450e703
5 changed files with 231 additions and 121 deletions

View file

@ -55,13 +55,13 @@ module Inspec::Resources
@protocol = params.fetch(:protocol, 'icmp')
end
return skip_resource 'Invalid protocol: only `tcp` and `icmp` protocols are support for the `host` resource.' unless
%w{icmp tcp}.include?(@protocol)
@host_provider = nil
if inspec.os.linux?
@host_provider = LinuxHostProvider.new(inspec)
elsif inspec.os.windows?
return skip_resource 'Invalid protocol: only `tcp` and `icmp` protocols are support for the `host` resource on your OS.' unless
%w{icmp tcp}.include?(@protocol)
@host_provider = WindowsHostProvider.new(inspec)
elsif inspec.os.darwin?
@host_provider = DarwinHostProvider.new(inspec)
@ -147,6 +147,69 @@ module Inspec::Resources
end
class UnixHostProvider < HostProvider
def initialize(inspec)
super
@has_nc = inspec.command('nc').exist?
@has_ncat = inspec.command('ncat').exist?
@has_net_redirections = inspec.command("strings `which bash` | grep -qE '/dev/(tcp|udp)/'").exit_status == 0
end
def missing_requirements(protocol)
missing = []
if %w{tcp udp}.include?(protocol) && !@has_nc && !@has_ncat
if @has_net_redirections
missing << "#{timeout} (part of coreutils) or netcat must be installed" unless inspec.command(timeout).exist?
else
missing << 'netcat must be installed'
end
end
missing
end
def ping(hostname, port, protocol)
if %w{tcp udp}.include?(protocol)
if @has_nc || @has_ncat
resp = inspec.command(netcat_check_command(hostname, port, protocol))
else
resp = inspec.command("#{timeout} 1 bash -c \"< /dev/#{protocol}/#{hostname}/#{port}\"")
end
else
# fall back to ping, but we can only test ICMP packages with ping
resp = inspec.command("ping -w 1 -c 1 #{hostname}")
end
{
success: resp.exit_status.to_i.zero?,
connection: resp.stderr,
socket: resp.stdout,
}
end
def netcat_check_command(hostname, port, protocol)
if @has_nc
base_cmd = 'nc'
elsif @has_ncat
base_cmd = 'ncat'
else
return
end
if protocol == 'udp'
extra_flags = '-u'
else
extra_flags = ''
end
"echo | #{base_cmd} -v -w 1 #{extra_flags} #{hostname} #{port}"
end
def timeout
'timeout'
end
def resolve_with_dig(hostname)
addresses = []
@ -191,28 +254,8 @@ module Inspec::Resources
end
class DarwinHostProvider < UnixHostProvider
def missing_requirements(protocol)
missing = []
if protocol == 'tcp'
missing << 'netcat must be installed' unless inspec.command('nc').exist?
end
missing
end
def ping(hostname, port, protocol)
if protocol == 'tcp'
resp = inspec.command("nc -vz -G 1 #{hostname} #{port}")
else
resp = inspec.command("ping -W 1 -c 1 #{hostname}")
end
{
success: resp.exit_status.to_i.zero?,
connection: resp.stderr,
socket: resp.stdout,
}
def timeout
'gtimeout'
end
def resolve(hostname)
@ -221,43 +264,6 @@ module Inspec::Resources
end
class LinuxHostProvider < UnixHostProvider
def missing_requirements(protocol)
missing = []
if protocol == 'tcp' && (!inspec.command('nc').exist? && !inspec.command('ncat').exist?)
missing << 'netcat must be installed'
end
missing
end
def ping(hostname, port, protocol)
if protocol == 'tcp'
resp = inspec.command(tcp_check_command(hostname, port))
else
# fall back to ping, but we can only test ICMP packages with ping
resp = inspec.command("ping -w 1 -c 1 #{hostname}")
end
{
success: resp.exit_status.to_i.zero?,
connection: resp.stderr,
socket: resp.stdout,
}
end
def tcp_check_command(hostname, port)
if inspec.command('nc').exist?
base_cmd = 'nc'
elsif inspec.command('ncat').exist?
base_cmd = 'ncat'
else
return
end
"echo | #{base_cmd} -v -w 1 #{hostname} #{port}"
end
def resolve(hostname)
resolve_with_getent(hostname)
end

View file

@ -415,13 +415,22 @@ class MockLoader
"modprobe --showconfig" => cmd.call('modprobe-config'),
# get-process cmdlet for processes resource
'$Proc = Get-Process -IncludeUserName | Where-Object {$_.Path -ne $null } | Select-Object PriorityClass,Id,CPU,PM,VirtualMemorySize,NPM,SessionId,Responding,StartTime,TotalProcessorTime,UserName,Path | ConvertTo-Csv -NoTypeInformation;$Proc.Replace("""","").Replace("`r`n","`n")' => cmd.call('get-process_processes'),
# host resource: check to see if netcat is installed
%{bash -c 'type "nc"'} => cmd.call('type-nc'),
'type "nc"' => cmd.call('type-nc'),
# host resource: netcat for TCP reachability check on linux
'echo | nc -v -w 1 example.com 1234' => cmd.call('nc-example-com'),
# host resource: TCP/UDP reachability check on linux
%{bash -c 'type "nc"'} => empty.call,
%{bash -c 'type "ncat"'} => empty.call,
%{bash -c 'type "timeout"'} => empty.call,
%{strings `which bash` | grep -qE '/dev/(tcp|udp)/'} => empty.call,
%{echo | nc -v -w 1 -u example.com 1234} => empty.call,
%{echo | nc -v -w 1 example.com 1234} => empty.call,
'timeout 1 bash -c "< /dev/tcp/example.com/1234"' => empty.call,
'timeout 1 bash -c "< /dev/udp/example.com/1234"' => empty.call,
# host resource: netcat for TCP reachability check on darwin
'nc -vz -G 1 example.com 1234' => cmd.call('nc-example-com'),
'type "nc"' => empty.call,
'type "ncat"' => empty.call,
'type "gtimeout"' => empty.call,
'nc -vz -G 1 example.com 1234' => empty.call,
'gtimeout 1 bash -c "< /dev/tcp/example.com/1234"' => empty.call,
'gtimeout 1 bash -c "< /dev/udp/example.com/1234"' => empty.call,
# host resource: test-netconnection for reachability check on windows
'Test-NetConnection -ComputerName microsoft.com -WarningAction SilentlyContinue -RemotePort 1234| Select-Object -Property ComputerName, TcpTestSucceeded, PingSucceeded | ConvertTo-Json' => cmd.call('Test-NetConnection'),
# postgres tests

View file

@ -55,6 +55,14 @@ describe 'Inspec::Resources::Host' do
_(resource.to_s).must_equal 'Host example.com port 1234 proto tcp'
end
it 'check host udp on ubuntu' do
resource = MockLoader.new(:ubuntu1404).load_resource('host', 'example.com', port: 1234, protocol: 'udp')
_(resource.resolvable?).must_equal true
_(resource.reachable?).must_equal true
_(resource.ipaddress).must_equal ["12.34.56.78", "2606:2800:220:1:248:1893:25c8:1946"]
_(resource.to_s).must_equal 'Host example.com port 1234 proto udp'
end
it 'check host tcp on centos 7' do
resource = MockLoader.new(:centos7).load_resource('host', 'example.com', port: 1234, protocol: 'tcp')
_(resource.resolvable?).must_equal true
@ -63,6 +71,14 @@ describe 'Inspec::Resources::Host' do
_(resource.to_s).must_equal 'Host example.com port 1234 proto tcp'
end
it 'check host udp on centos 7' do
resource = MockLoader.new(:centos7).load_resource('host', 'example.com', port: 1234, protocol: 'udp')
_(resource.resolvable?).must_equal true
_(resource.reachable?).must_equal true
_(resource.ipaddress).must_equal ["12.34.56.78", "2606:2800:220:1:248:1893:25c8:1946"]
_(resource.to_s).must_equal 'Host example.com port 1234 proto udp'
end
it 'check host tcp on darwin' do
resource = MockLoader.new(:osx104).load_resource('host', 'example.com', port: 1234, protocol: 'tcp')
_(resource.resolvable?).must_equal true
@ -71,6 +87,14 @@ describe 'Inspec::Resources::Host' do
_(resource.to_s).must_equal 'Host example.com port 1234 proto tcp'
end
it 'check host udp on darwin' do
resource = MockLoader.new(:osx104).load_resource('host', 'example.com', port: 1234, protocol: 'udp')
_(resource.resolvable?).must_equal true
_(resource.reachable?).must_equal true
_(resource.ipaddress).must_equal ["12.34.56.78", "2606:2800:220:1:248:1893:25c8:1946"]
_(resource.to_s).must_equal 'Host example.com port 1234 proto udp'
end
it 'check host tcp on windows' do
resource = MockLoader.new(:windows).load_resource('host', 'microsoft.com', port: 1234, protocol: 'tcp')
_(resource.resolvable?).must_equal true
@ -89,12 +113,31 @@ describe 'Inspec::Resources::Host' do
end
describe Inspec::Resources::UnixHostProvider do
let(:provider) { Inspec::Resources::UnixHostProvider.new(inspec) }
let(:inspec) { mock('inspec-backend') }
let(:nc_command) { mock('nc-command') }
let(:ncat_command) { mock('ncat-command') }
let(:timeout_command) { mock("timeout-command") }
let(:strings_command) { mock("strings-command") }
before do
inspec.stubs(:command).with('nc').returns(nc_command)
inspec.stubs(:command).with('ncat').returns(ncat_command)
inspec.stubs(:command).with('timeout').returns(timeout_command)
inspec.stubs(:command).with('gtimeout').returns(timeout_command)
inspec.stubs(:command).with("strings `which bash` | grep -qE '/dev/(tcp|udp)/'").returns(strings_command)
end
describe '#resolve_with_dig' do
let(:provider) { Inspec::Resources::UnixHostProvider.new(inspec) }
let(:inspec) { mock('inspec-backend') }
let(:v4_command) { mock('v4_command') }
let(:v6_command) { mock('v6_command') }
before do
strings_command.stubs(:exit_status).returns(0)
nc_command.stubs(:exist?).returns(false)
ncat_command.stubs(:exist?).returns(false)
end
it 'returns an array of IP addresses' do
ipv4_command_output = <<-EOL
a.cname.goes.here
@ -169,16 +212,20 @@ EOL
end
describe '#resolve_with_getent' do
before do
strings_command.stubs(:exit_status).returns(0)
nc_command.stubs(:exist?).returns(false)
ncat_command.stubs(:exist?).returns(false)
end
it 'returns an array of IP addresses when successful' do
command_output = "123.123.123.123 STREAM testdomain.com\n2607:f8b0:4004:805::200e STREAM\n"
command = mock('getent_command')
command.stubs(:stdout).returns(command_output)
command.stubs(:exit_status).returns(0)
inspec = mock('inspec')
inspec.stubs(:command).with('getent ahosts testdomain.com').returns(command)
provider = Inspec::Resources::UnixHostProvider.new(inspec)
provider.resolve_with_getent('testdomain.com').must_equal(['123.123.123.123', '2607:f8b0:4004:805::200e'])
end
@ -186,84 +233,132 @@ EOL
command = mock('getent_command')
command.stubs(:exit_status).returns(1)
inspec = mock('inspec')
inspec.stubs(:command).with('getent ahosts testdomain.com').returns(command)
provider = Inspec::Resources::UnixHostProvider.new(inspec)
provider.resolve_with_getent('testdomain.com').must_be_nil
end
end
end
describe Inspec::Resources::LinuxHostProvider do
let(:provider) { Inspec::Resources::LinuxHostProvider.new(inspec) }
let(:inspec) { mock('inspec-backend') }
let(:nc_command) { mock('nc-command') }
let(:ncat_command) { mock('ncat-command') }
before do
provider.stubs(:inspec).returns(inspec)
describe "#ping" do
let(:command_response) { mock('response') }
before do
strings_command.stubs(:exit_status).returns(0)
ncat_command.stubs(:exist?).returns(false)
command_response.stubs(:exit_status).returns('0')
command_response.stubs(:stdout).returns('foo')
command_response.stubs(:stderr).returns('bar')
end
it "calls netcat if available" do
nc_command.stubs(:exist?).returns(true)
inspec.expects(:command).with('echo | nc -v -w 1 example.com 1234').returns(command_response)
provider.ping('example.com', '1234', 'tcp')
end
it "uses bash if netcat not available" do
nc_command.stubs(:exist?).returns(false)
inspec.expects(:command).with('timeout 1 bash -c "< /dev/tcp/example.com/1234"').returns(command_response)
provider.ping('example.com', '1234', 'tcp')
end
it "uses bash if netcat not available on Darwin" do
nc_command.stubs(:exist?).returns(false)
inspec.expects(:command).with('gtimeout 1 bash -c "< /dev/tcp/example.com/1234"').returns(command_response)
darwin_provider = Inspec::Resources::DarwinHostProvider.new(inspec)
darwin_provider.ping('example.com', '1234', 'tcp')
end
end
describe '#missing_requirements' do
it "returns an empty array if nc is installed but ncat is not installed" do
inspec.stubs(:command).with('nc').returns(nc_command)
nc_command.stubs(:exist?).returns(true)
inspec.stubs(:command).with('ncat').returns(ncat_command)
ncat_command.stubs(:exist?).returns(false)
describe 'bash with net redirects and no netcat' do
before do
strings_command.stubs(:exit_status).returns(0)
nc_command.stubs(:exist?).returns(false)
ncat_command.stubs(:exist?).returns(false)
end
provider.missing_requirements('tcp').must_equal([])
it "returns an empty array if timeout is available" do
timeout_command.stubs(:exist?).returns(true)
provider.missing_requirements('tcp').must_equal([])
end
it "returns a missing requirement when timeout is missing" do
timeout_command.stubs(:exist?).returns(false)
provider.missing_requirements('tcp').must_equal(['timeout (part of coreutils) or netcat must be installed'])
end
end
it "returns an empty array if nc is not installed but ncat is installed" do
inspec.stubs(:command).with('nc').returns(nc_command)
nc_command.stubs(:exist?).returns(false)
inspec.stubs(:command).with('ncat').returns(ncat_command)
ncat_command.stubs(:exist?).returns(true)
describe 'bash without net redirects' do
before do
strings_command.stubs(:exit_status).returns(1)
end
provider.missing_requirements('tcp').must_equal([])
end
it "returns an empty array if nc is installed but ncat is not installed" do
nc_command.stubs(:exist?).returns(true)
ncat_command.stubs(:exist?).returns(false)
provider.missing_requirements('tcp').must_equal([])
end
it "returns an empty array if both nc and ncat are installed" do
inspec.stubs(:command).with('nc').returns(nc_command)
nc_command.stubs(:exist?).returns(true)
inspec.stubs(:command).with('ncat').returns(ncat_command)
ncat_command.stubs(:exist?).returns(true)
it "returns an empty array if nc is not installed but ncat is installed" do
nc_command.stubs(:exist?).returns(false)
ncat_command.stubs(:exist?).returns(true)
provider.missing_requirements('tcp').must_equal([])
end
provider.missing_requirements('tcp').must_equal([])
end
it "returns an empty array if both nc and ncat are installed" do
nc_command.stubs(:exist?).returns(true)
ncat_command.stubs(:exist?).returns(true)
provider.missing_requirements('tcp').must_equal([])
end
it "returns a missing requirement when neither nc nor ncat are installed" do
inspec.stubs(:command).with('nc').returns(nc_command)
nc_command.stubs(:exist?).returns(false)
inspec.stubs(:command).with('ncat').returns(ncat_command)
ncat_command.stubs(:exist?).returns(false)
provider.missing_requirements('tcp').must_equal(['netcat must be installed'])
it "returns a missing requirement when neither nc nor ncat are installed" do
nc_command.stubs(:exist?).returns(false)
ncat_command.stubs(:exist?).returns(false)
provider.missing_requirements('tcp').must_equal(['netcat must be installed'])
end
end
end
describe '#tcp_check_command' do
it 'returns an nc command when nc exists' do
inspec.expects(:command).with('nc').returns(nc_command)
nc_command.expects(:exist?).returns(true)
provider.tcp_check_command('foo', 1234).must_equal 'echo | nc -v -w 1 foo 1234'
describe '#netcat_check_command' do
before do
strings_command.stubs(:exit_status).returns(1)
end
it 'returns an ncat command when nc does not exist but ncat exists' do
inspec.expects(:command).with('nc').returns(nc_command)
inspec.expects(:command).with('ncat').returns(ncat_command)
it 'returns an nc command when nc exists tcp' do
nc_command.expects(:exist?).returns(true)
ncat_command.expects(:exist?).returns(false)
provider.netcat_check_command('foo', 1234, 'tcp').must_equal 'echo | nc -v -w 1 foo 1234'
end
it 'returns an nc command when nc exists udp' do
nc_command.expects(:exist?).returns(true)
ncat_command.expects(:exist?).returns(false)
provider.netcat_check_command('foo', 1234, 'udp').must_equal 'echo | nc -v -w 1 -u foo 1234'
end
it 'returns an ncat command when nc does not exist but ncat exists tcp' do
nc_command.expects(:exist?).returns(false)
ncat_command.expects(:exist?).returns(true)
provider.tcp_check_command('foo', 1234).must_equal 'echo | ncat -v -w 1 foo 1234'
provider.netcat_check_command('foo', 1234, 'tcp').must_equal 'echo | ncat -v -w 1 foo 1234'
end
it 'returns an ncat command when nc does not exist but ncat exists udp' do
nc_command.expects(:exist?).returns(false)
ncat_command.expects(:exist?).returns(true)
provider.netcat_check_command('foo', 1234, 'udp').must_equal 'echo | ncat -v -w 1 -u foo 1234'
end
it 'returns nil if neither nc or ncat exist' do
inspec.expects(:command).with('nc').returns(nc_command)
inspec.expects(:command).with('ncat').returns(ncat_command)
nc_command.expects(:exist?).returns(false)
ncat_command.expects(:exist?).returns(false)
provider.tcp_check_command('foo', 1234).must_be_nil
provider.netcat_check_command('foo', 1234, 'tcp').must_be_nil
end
end
end