145 lines
3.9 KiB
Ruby
145 lines
3.9 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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class SSHPublicKey
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include Gitlab::Utils::StrongMemoize
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Technology = Struct.new(:name, :key_class, :supported_sizes, :supported_algorithms)
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# See https://man.openbsd.org/sshd#AUTHORIZED_KEYS_FILE_FORMAT for the list of
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# supported algorithms.
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TECHNOLOGIES = [
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Technology.new(:rsa, SSHData::PublicKey::RSA, [1024, 2048, 3072, 4096], %w(ssh-rsa)),
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Technology.new(:dsa, SSHData::PublicKey::DSA, [1024, 2048, 3072], %w(ssh-dss)),
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Technology.new(:ecdsa, SSHData::PublicKey::ECDSA, [256, 384, 521], %w(ecdsa-sha2-nistp256 ecdsa-sha2-nistp384 ecdsa-sha2-nistp521)),
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Technology.new(:ed25519, SSHData::PublicKey::ED25519, [256], %w(ssh-ed25519)),
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Technology.new(:ecdsa_sk, SSHData::PublicKey::SKECDSA, [256], %w(sk-ecdsa-sha2-nistp256@openssh.com)),
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Technology.new(:ed25519_sk, SSHData::PublicKey::SKED25519, [256], %w(sk-ssh-ed25519@openssh.com))
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].freeze
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def self.technologies
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if Gitlab::FIPS.enabled?
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Gitlab::FIPS::SSH_KEY_TECHNOLOGIES
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else
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TECHNOLOGIES
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end
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end
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def self.technology(name)
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technologies.find { |tech| tech.name.to_s == name.to_s }
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end
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def self.technology_for_key(key)
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technologies.find { |tech| key.instance_of?(tech.key_class) }
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end
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def self.supported_types
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technologies.map(&:name)
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end
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def self.supported_sizes(name)
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technology(name).supported_sizes
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end
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def self.supported_algorithms
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technologies.flat_map { |tech| tech.supported_algorithms }
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end
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def self.supported_algorithms_for_name(name)
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technology(name).supported_algorithms
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end
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def self.sanitize(key_content)
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ssh_type, *parts = key_content.strip.split
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return key_content if parts.empty?
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parts.each_with_object(+"#{ssh_type} ").with_index do |(part, content), index|
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content << part
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if self.new(content).valid?
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break [content, parts[index + 1]].compact.join(' ') # Add the comment part if present
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elsif parts.size == index + 1 # return original content if we've reached the last element
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break key_content
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end
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end
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end
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attr_reader :key_text, :key
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def initialize(key_text)
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@key_text = key_text
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# We need to strip options to parse key with options or in known_hosts
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# format. See https://man.openbsd.org/sshd#AUTHORIZED_KEYS_FILE_FORMAT
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# and https://man.openbsd.org/sshd#SSH_KNOWN_HOSTS_FILE_FORMAT
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key_text_without_options = @key_text.to_s.match(/(\A|\s)(#{self.class.supported_algorithms.join('|')}).*/).to_s
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@key =
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begin
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SSHData::PublicKey.parse_openssh(key_text_without_options)
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rescue SSHData::DecodeError
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end
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end
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def valid?
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key.present?
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end
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def type
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technology.name if valid?
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end
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def fingerprint
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key.fingerprint(md5: true) if valid?
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end
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def fingerprint_sha256
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'SHA256:' + key.fingerprint(md5: false) if valid?
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end
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def bits
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return unless valid?
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case type
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when :rsa
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key.n.num_bits
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when :dsa
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key.p.num_bits
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when :ecdsa
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key.openssl.group.order.num_bits
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when :ed25519
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256
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when :ecdsa_sk
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256
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when :ed25519_sk
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256
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end
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end
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def banned?
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return false unless valid?
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banned_ssh_keys.fetch(type.to_s, []).include?(fingerprint_sha256)
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end
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private
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def banned_ssh_keys
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path = Rails.root.join('config/security/banned_ssh_keys.yml')
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config = YAML.load_file(path) if File.exist?(path)
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config || {}
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end
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strong_memoize_attr :banned_ssh_keys
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def technology
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@technology ||=
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self.class.technology_for_key(key) || raise_unsupported_key_type_error
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end
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def raise_unsupported_key_type_error
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raise("Unsupported key type: #{key.class}")
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end
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end
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end
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