Add a function to validate an x509 RSA key pair

README.markdown

@@ -1182,6 +1182,22 @@ Instead, use:
 
 *Type*: statement.
 
+#### `validate_x509_rsa_key_pair`
+
+Validates a PEM-formatted X.509 certificate and private key using OpenSSL.
+Verifies that the certficate's signature was created from the supplied key.
+
+Fails catalog compilation if any value fails this check.
+
+Takes two arguments, the first argument must be a X.509 certificate and the
+second must be an RSA private key:
+
+  ~~~
+  validate_x509_rsa_key_pair($cert, $key)
+  ~~~
+
+*Type*: statement.
+
 #### `values`
 
 Returns the values of a given hash. For example, given `$hash = {'a'=1, 'b'=2, 'c'=3} values($hash)` returns [1,2,3].

lib/puppet/parser/functions/validate_x509_rsa_key_pair.rb

@@ -0,0 +1,47 @@
+module Puppet::Parser::Functions
+
+  newfunction(:validate_x509_rsa_key_pair, :doc => <<-ENDHEREDOC
+    Validates a PEM-formatted X.509 certificate and RSA private key using
+    OpenSSL. Verifies that the certficate's signature was created from the
+    supplied key.
+
+    Fail compilation if any value fails this check.
+
+    validate_x509_rsa_key_pair($cert, $key)
+
+    ENDHEREDOC
+  ) do |args|
+
+    require 'openssl'
+
+    NUM_ARGS = 2 unless defined? NUM_ARGS
+
+    unless args.length == NUM_ARGS then
+      raise Puppet::ParseError,
+        ("validate_x509_rsa_key_pair(): wrong number of arguments (#{args.length}; must be #{NUM_ARGS})")
+    end
+
+    args.each do |arg|
+      unless arg.is_a?(String)
+        raise Puppet::ParseError, "#{arg.inspect} is not a string."
+      end
+    end
+
+    begin
+      cert = OpenSSL::X509::Certificate.new(args[0])
+    rescue OpenSSL::X509::CertificateError => e
+      raise Puppet::ParseError, "Not a valid x509 certificate: #{e}"
+    end
+
+    begin
+      key = OpenSSL::PKey::RSA.new(args[1])
+    rescue OpenSSL::PKey::RSAError => e
+      raise Puppet::ParseError, "Not a valid RSA key: #{e}"
+    end
+
+    unless cert.verify(key)
+      raise Puppet::ParseError, "Certificate signature does not match supplied key"
+    end
+  end
+
+end

spec/functions/validate_x509_rsa_key_pair_spec.rb

@@ -0,0 +1,180 @@
+require 'spec_helper'
+
+describe 'validate_x509_rsa_key_pair' do
+
+  let(:valid_cert) do
+  <<EOS
+-----BEGIN CERTIFICATE-----
+MIIC9jCCAeCgAwIBAgIRAK11n3X7aypJ7FPM8UFyAeowCwYJKoZIhvcNAQELMBIx
+EDAOBgNVBAoTB0FjbWUgQ28wHhcNMTUxMTIzMjIzOTU4WhcNMTYxMTIyMjIzOTU4
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+-----END CERTIFICATE-----
+EOS
+  end
+
+  let(:valid_key) do
+  <<EOS
+-----BEGIN RSA PRIVATE KEY-----
+MIIEogIBAAKCAQEAz9bY/piKahD10AiJSfbI2A8NG5UwRz0r9T/WfvNVdhgrsGFg
+NQjvpUoZnNJpQIHBbgMOiXqfATFjJl5FjEkSf7GUHohlGVls9MX2JmVvknzsiitd
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+KAf7Dfqi608zBdnPWHacre2Y35gPHB00nFQOLS6u46aBNSq07YA=
+-----END RSA PRIVATE KEY-----
+EOS
+  end
+
+  let(:another_valid_key) do
+  <<EOS
+-----BEGIN RSA PRIVATE KEY-----
+MIIEpAIBAAKCAQEAoISxYJBTPAeAzFnm+lE/ljLlmGal2Xr3vwZKkvJiuKA/m4QJ
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+-----END RSA PRIVATE KEY-----
+EOS
+  end
+
+  let(:valid_cert_but_indented) do
+    valid_cert.gsub(/^/, '  ')
+  end
+
+  let(:valid_key_but_indented) do
+    valid_key.gsub(/^/, '  ')
+  end
+
+  let(:malformed_cert) do
+    truncate_middle(valid_cert)
+  end
+
+  let(:malformed_key) do
+    truncate_middle(valid_key)
+  end
+
+  let(:bad_cert) do
+    'foo'
+  end
+
+  let(:bad_key) do
+    'bar'
+  end
+
+  context 'function signature validation' do
+    it { is_expected.not_to eq(nil) }
+    it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+    it { is_expected.to run.with_params(0, 1, 2, 3).and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+  end
+
+  context 'valid input' do
+    describe 'valid certificate and key' do
+      it { is_expected.to run.with_params(valid_cert, valid_key) }
+    end
+  end
+
+  context 'bad input' do
+    describe 'valid certificate, valid but indented key' do
+      it { is_expected.to run.with_params(valid_cert, valid_key_but_indented).and_raise_error(Puppet::ParseError, /Not a valid RSA key/) }
+    end
+
+    describe 'valid certificate, malformed key' do
+      it { is_expected.to run.with_params(valid_cert, malformed_key).and_raise_error(Puppet::ParseError, /Not a valid RSA key/) }
+    end
+
+    describe 'valid certificate, bad key' do
+      it { is_expected.to run.with_params(valid_cert, bad_key).and_raise_error(Puppet::ParseError, /Not a valid RSA key/) }
+    end
+
+    describe 'valid but indented certificate, valid key' do
+      it { is_expected.to run.with_params(valid_cert_but_indented, valid_key).and_raise_error(Puppet::ParseError, /Not a valid x509 certificate/) }
+    end
+
+    describe 'malformed certificate, valid key' do
+      it { is_expected.to run.with_params(malformed_cert, valid_key).and_raise_error(Puppet::ParseError, /Not a valid x509 certificate/) }
+    end
+
+    describe 'bad certificate, valid key' do
+      it { is_expected.to run.with_params(bad_cert, valid_key).and_raise_error(Puppet::ParseError, /Not a valid x509 certificate/) }
+    end
+
+    describe 'validate certificate and key; certficate not signed by key' do
+      it { is_expected.to run.with_params(valid_cert, another_valid_key).and_raise_error(Puppet::ParseError, /Certificate signature does not match supplied key/) }
+    end
+
+    describe 'valid cert and key but arguments in wrong order' do
+      it { is_expected.to run.with_params(valid_key, valid_cert).and_raise_error(Puppet::ParseError, /Not a valid x509 certificate/) }
+    end
+
+    describe 'non-string arguments' do
+      it { is_expected.to run.with_params({}, {}).and_raise_error(Puppet::ParseError, /is not a string/) }
+      it { is_expected.to run.with_params(1, 1).and_raise_error(Puppet::ParseError, /is not a string/) }
+      it { is_expected.to run.with_params(true, true).and_raise_error(Puppet::ParseError, /is not a string/) }
+      it { is_expected.to run.with_params("foo", {}).and_raise_error(Puppet::ParseError, /is not a string/) }
+      it { is_expected.to run.with_params(1, "bar").and_raise_error(Puppet::ParseError, /is not a string/) }
+      it { is_expected.to run.with_params("baz", true).and_raise_error(Puppet::ParseError, /is not a string/) }
+    end
+  end
+
+  def truncate_middle(string)
+    chars_to_truncate = 48
+    middle = (string.length / 2).floor
+    start_pos = middle - (chars_to_truncate / 2)
+    end_pos = middle + (chars_to_truncate / 2)
+
+    string[start_pos...end_pos] = ''
+    return string
+  end
+end