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_NAME =

Used internally to select the signing digest from all computed digests

"SHA256"
RSA_DSA_KEY_LENGTH =

Length of keys created by RSA and DSA keys

3072
DEFAULT_KEY_ALGORITHM =

Default algorithm to use when building a key pair

"RSA"
EC_NAME =

Named curve used for Elliptic Curve

"secp384r1"
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

86_400
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 385

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 401

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

  cert.public_key = get_public_key(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 440

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 452

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_digest(algorithm = DIGEST_NAME) ⇒ Object

Creates a new digest instance using the specified algorithm. The default is SHA256.



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# File 'lib/rubygems/security.rb', line 462

def self.create_digest(algorithm = DIGEST_NAME)
  OpenSSL::Digest.new(algorithm)
end

.create_key(algorithm) ⇒ Object

Creates a new key pair of the specified algorithm. RSA, DSA, and EC are supported.



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# File 'lib/rubygems/security.rb', line 470

def self.create_key(algorithm)
  if defined?(OpenSSL::PKey)
    case algorithm.downcase
    when "dsa"
      OpenSSL::PKey::DSA.new(RSA_DSA_KEY_LENGTH)
    when "rsa"
      OpenSSL::PKey::RSA.new(RSA_DSA_KEY_LENGTH)
    when "ec"
      OpenSSL::PKey::EC.generate(EC_NAME)
    else
      raise Gem::Security::Exception,
      "#{algorithm} algorithm not found. RSA, DSA, and EC algorithms are supported."
    end
  end
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 489

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

  cn, dcs = email_address.split "@"

  dcs = dcs.split "."

  OpenSSL::X509::Name.new([
    ["CN", cn],
    *dcs.map {|dc| ["DC", dc] },
  ])
end

.get_public_key(key) ⇒ Object

Gets the right public key from a PKey instance



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# File 'lib/rubygems/security.rb', line 425

def self.get_public_key(key)
  # Ruby 3.0 (Ruby/OpenSSL 2.2) or later
  return OpenSSL::PKey.read(key.public_to_der) if key.respond_to?(:public_to_der)
  return key.public_key unless key.is_a?(OpenSSL::PKey::EC)

  ec_key = OpenSSL::PKey::EC.new(key.group.curve_name)
  ec_key.public_key = key.public_key
  ec_key
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

Raises:



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# File 'lib/rubygems/security.rb', line 508

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.to_s unless
    expired_certificate.check_private_key(private_key)

  unless expired_certificate.subject.to_s ==
         expired_certificate.issuer.to_s
    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

.reset ⇒ Object

Resets the trust directory for verifying gems.



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# File 'lib/rubygems/security.rb', line 533

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_NAME. Uses the default certificate validity range and extensions.

Returns the newly signed certificate.



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# File 'lib/rubygems/security.rb', line 544

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_NAME
end

.trust_dir ⇒ Object

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



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# File 'lib/rubygems/security.rb', line 572

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 583

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

.write(pemmable, path, permissions = 0o600, 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 592

def self.write(pemmable, path, permissions = 0o600, passphrase = nil, cipher = KEY_CIPHER)
  path = File.expand_path path

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

  path
end