Module: Gem::Security

Defined in:
lib/rubygems/security.rb,
lib/rubygems/security_option.rb,
lib/rubygems/security/policies.rb,
lib/rubygems/commands/unpack_command.rb

Overview

forward-declare

Defined Under Namespace

Classes: Exception, Policy, Signer, TrustDir

Constant Summary collapse

DIGEST_ALGORITHM =

Digest algorithm used to sign gems

if defined?(OpenSSL::Digest::SHA256) then
  OpenSSL::Digest::SHA256
elsif defined?(OpenSSL::Digest::SHA1) then
  OpenSSL::Digest::SHA1
else
  require 'digest'
  Digest::SHA512
end
DIGEST_NAME =

Used internally to select the signing digest from all computed digests

if DIGEST_ALGORITHM.method_defined? :name then
  DIGEST_ALGORITHM.new.name
else
  DIGEST_ALGORITHM.name[/::([^:]+)\z/, 1]
end
KEY_ALGORITHM =

Algorithm for creating the key pair used to sign gems

if defined?(OpenSSL::PKey::RSA) then
  OpenSSL::PKey::RSA
end
KEY_LENGTH =

Length of keys created by KEY_ALGORITHM

3072
KEY_CIPHER =

Cipher used to encrypt the key pair used to sign gems. Must be in the list returned by OpenSSL::Cipher.ciphers

OpenSSL::Cipher.new('AES-256-CBC')
ONE_DAY =

One day in seconds

86400
ONE_YEAR =

One year in seconds

ONE_DAY * 365
EXTENSIONS =

The default set of extensions are:

  • The certificate is not a certificate authority

  • The key for the certificate may be used for key and data encipherment and digital signatures

  • The certificate contains a subject key identifier

{
  'basicConstraints'     => 'CA:FALSE',
  'keyUsage'             =>
    'keyEncipherment,dataEncipherment,digitalSignature',
  'subjectKeyIdentifier' => 'hash',
}.freeze
NoSecurity =

No security policy: all package signature checks are disabled.

Policy.new(
  'No Security',
  :verify_data      => false,
  :verify_signer    => false,
  :verify_chain     => false,
  :verify_root      => false,
  :only_trusted     => false,
  :only_signed      => false
)
AlmostNoSecurity =

AlmostNo security policy: only verify that the signing certificate is the one that actually signed the data. Make no attempt to verify the signing certificate chain.

This policy is basically useless. better than nothing, but can still be easily spoofed, and is not recommended.

Policy.new(
  'Almost No Security',
  :verify_data      => true,
  :verify_signer    => false,
  :verify_chain     => false,
  :verify_root      => false,
  :only_trusted     => false,
  :only_signed      => false
)
LowSecurity =

Low security policy: only verify that the signing certificate is actually the gem signer, and that the signing certificate is valid.

This policy is better than nothing, but can still be easily spoofed, and is not recommended.

Policy.new(
  'Low Security',
  :verify_data      => true,
  :verify_signer    => true,
  :verify_chain     => false,
  :verify_root      => false,
  :only_trusted     => false,
  :only_signed      => false
)
MediumSecurity =

Medium security policy: verify the signing certificate, verify the signing certificate chain all the way to the root certificate, and only trust root certificates that we have explicitly allowed trust for.

This security policy is reasonable, but it allows unsigned packages, so a malicious person could simply delete the package signature and pass the gem off as unsigned.

Policy.new(
  'Medium Security',
  :verify_data      => true,
  :verify_signer    => true,
  :verify_chain     => true,
  :verify_root      => true,
  :only_trusted     => true,
  :only_signed      => false
)
HighSecurity =

High security policy: only allow signed gems to be installed, verify the signing certificate, verify the signing certificate chain all the way to the root certificate, and only trust root certificates that we have explicitly allowed trust for.

This security policy is significantly more difficult to bypass, and offers a reasonable guarantee that the contents of the gem have not been altered.

Policy.new(
  'High Security',
  :verify_data      => true,
  :verify_signer    => true,
  :verify_chain     => true,
  :verify_root      => true,
  :only_trusted     => true,
  :only_signed      => true
)
SigningPolicy =

Policy used to verify a certificate and key when signing a gem

Policy.new(
  'Signing Policy',
  :verify_data      => false,
  :verify_signer    => true,
  :verify_chain     => true,
  :verify_root      => true,
  :only_trusted     => false,
  :only_signed      => false
)
Policies =

Hash of configured security policies

{
  'NoSecurity'       => NoSecurity,
  'AlmostNoSecurity' => AlmostNoSecurity,
  'LowSecurity'      => LowSecurity,
  'MediumSecurity'   => MediumSecurity,
  'HighSecurity'     => HighSecurity,
  # SigningPolicy is not intended for use by `gem -P` so do not list it
}.freeze

Class Method Summary collapse

Class Method Details

.alt_name_or_x509_entry(certificate, x509_entry) ⇒ Object


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# File 'lib/rubygems/security.rb', line 406

def self.alt_name_or_x509_entry certificate, x509_entry
  alt_name = certificate.extensions.find do |extension|
    extension.oid == "#{x509_entry}AltName"
  end

  return alt_name.value if alt_name

  certificate.send x509_entry
end

.create_cert(subject, key, age = ONE_YEAR, extensions = EXTENSIONS, serial = 1) ⇒ Object

Creates an unsigned certificate for subject and key. The lifetime of the key is from the current time to age which defaults to one year.

The extensions restrict the key to the indicated uses.


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# File 'lib/rubygems/security.rb', line 422

def self.create_cert subject, key, age = ONE_YEAR, extensions = EXTENSIONS,
                     serial = 1
  cert = OpenSSL::X509::Certificate.new

  cert.public_key = key.public_key
  cert.version    = 2
  cert.serial     = serial

  cert.not_before = Time.now
  cert.not_after  = Time.now + age

  cert.subject    = subject

  ef = OpenSSL::X509::ExtensionFactory.new nil, cert

  cert.extensions = extensions.map do |ext_name, value|
    ef.create_extension ext_name, value
  end

  cert
end

.create_cert_email(email, key, age = ONE_YEAR, extensions = EXTENSIONS) ⇒ Object

Creates a self-signed certificate with an issuer and subject from email, a subject alternative name of email and the given extensions for the key.


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# File 'lib/rubygems/security.rb', line 449

def self.create_cert_email email, key, age = ONE_YEAR, extensions = EXTENSIONS
  subject = email_to_name email

  extensions = extensions.merge "subjectAltName" => "email:#{email}"

  create_cert_self_signed subject, key, age, extensions
end

.create_cert_self_signed(subject, key, age = ONE_YEAR, extensions = EXTENSIONS, serial = 1) ⇒ Object

Creates a self-signed certificate with an issuer and subject of subject and the given extensions for the key.


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# File 'lib/rubygems/security.rb', line 461

def self.create_cert_self_signed subject, key, age = ONE_YEAR,
                                 extensions = EXTENSIONS, serial = 1
  certificate = create_cert subject, key, age, extensions

  sign certificate, key, certificate, age, extensions, serial
end

.create_key(length = KEY_LENGTH, algorithm = KEY_ALGORITHM) ⇒ Object

Creates a new key pair of the specified length and algorithm. The default is a 3072 bit RSA key.


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# File 'lib/rubygems/security.rb', line 472

def self.create_key length = KEY_LENGTH, algorithm = KEY_ALGORITHM
  algorithm.new length
end

.email_to_name(email_address) ⇒ Object

Turns email_address into an OpenSSL::X509::Name


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# File 'lib/rubygems/security.rb', line 479

def self.email_to_name email_address
  email_address = email_address.gsub(/[^\[email protected]]+/i, '_')

  cn, dcs = email_address.split '@'

  dcs = dcs.split '.'

  name = "CN=#{cn}/#{dcs.map { |dc| "DC=#{dc}" }.join '/'}"

  OpenSSL::X509::Name.parse name
end

.re_sign(expired_certificate, private_key, age = ONE_YEAR, extensions = EXTENSIONS) ⇒ Object

Signs expired_certificate with private_key if the keys match and the expired certificate was self-signed. – TODO increment serial


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# File 'lib/rubygems/security.rb', line 497

def self.re_sign expired_certificate, private_key, age = ONE_YEAR,
                 extensions = EXTENSIONS
  raise Gem::Security::Exception,
        "incorrect signing key for re-signing " +
        "#{expired_certificate.subject}" unless
    expired_certificate.public_key.to_pem == private_key.public_key.to_pem

  unless expired_certificate.subject.to_s ==
         expired_certificate.issuer.to_s then
    subject = alt_name_or_x509_entry expired_certificate, :subject
    issuer  = alt_name_or_x509_entry expired_certificate, :issuer

    raise Gem::Security::Exception,
          "#{subject} is not self-signed, contact #{issuer} " +
          "to obtain a valid certificate"
  end

  serial = expired_certificate.serial + 1

  create_cert_self_signed(expired_certificate.subject, private_key, age,
                          extensions, serial)
end

.resetObject

Resets the trust directory for verifying gems.


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# File 'lib/rubygems/security.rb', line 523

def self.reset
  @trust_dir = nil
end

.sign(certificate, signing_key, signing_cert, age = ONE_YEAR, extensions = EXTENSIONS, serial = 1) ⇒ Object

Sign the public key from certificate with the signing_key and signing_cert, using the Gem::Security::DIGEST_ALGORITHM. Uses the default certificate validity range and extensions.

Returns the newly signed certificate.


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# File 'lib/rubygems/security.rb', line 534

def self.sign certificate, signing_key, signing_cert,
              age = ONE_YEAR, extensions = EXTENSIONS, serial = 1
  signee_subject = certificate.subject
  signee_key     = certificate.public_key

  alt_name = certificate.extensions.find do |extension|
    extension.oid == 'subjectAltName'
  end

  extensions = extensions.merge 'subjectAltName' => alt_name.value if
    alt_name

  issuer_alt_name = signing_cert.extensions.find do |extension|
    extension.oid == 'subjectAltName'
  end

  extensions = extensions.merge 'issuerAltName' => issuer_alt_name.value if
    issuer_alt_name

  signed = create_cert signee_subject, signee_key, age, extensions, serial
  signed.issuer = signing_cert.subject

  signed.sign signing_key, Gem::Security::DIGEST_ALGORITHM.new
end

.trust_dirObject

Returns a Gem::Security::TrustDir which wraps the directory where trusted certificates live.


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# File 'lib/rubygems/security.rb', line 563

def self.trust_dir
  return @trust_dir if @trust_dir

  dir = File.join Gem.user_home, '.gem', 'trust'

  @trust_dir ||= Gem::Security::TrustDir.new dir
end

.trusted_certificates(&block) ⇒ Object

Enumerates the trusted certificates via Gem::Security::TrustDir.


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# File 'lib/rubygems/security.rb', line 574

def self.trusted_certificates &block
  trust_dir.each_certificate(&block)
end

.write(pemmable, path, permissions = 0600, passphrase = nil, cipher = KEY_CIPHER) ⇒ Object

Writes pemmable, which must respond to to_pem to path with the given permissions. If passed cipher and passphrase those arguments will be passed to to_pem.


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# File 'lib/rubygems/security.rb', line 583

def self.write pemmable, path, permissions = 0600, passphrase = nil, cipher = KEY_CIPHER
  path = File.expand_path path

  File.open path, 'wb', permissions do |io|
    if passphrase and cipher
      io.write pemmable.to_pem cipher, passphrase
    else
      io.write pemmable.to_pem
    end
  end

  path
end