74 lines
2.2 KiB
Ruby
74 lines
2.2 KiB
Ruby
# frozen_string_literal: true
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# Signature verification with ed25519 keys
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# requires this gem to be loaded.
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require 'ed25519'
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module Gitlab
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module Ssh
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class Signature
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include Gitlab::Utils::StrongMemoize
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def initialize(signature_text, signed_text, committer_email)
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@signature_text = signature_text
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@signed_text = signed_text
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@committer_email = committer_email
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end
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def verification_status
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strong_memoize(:verification_status) do
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next :unverified unless all_attributes_present?
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next :unverified unless valid_signature_blob? && committer
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next :unknown_key unless signed_by_key
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next :other_user unless signed_by_key.user == committer
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:verified
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end
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end
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private
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def all_attributes_present?
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# Signing an empty string is valid, but signature_text and committer_email
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# must be non-empty.
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@signed_text && @signature_text.present? && @committer_email.present?
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end
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# Verifies the signature using the public key embedded in the blob.
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# This proves that the signed_text was signed by the private key
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# of the public key identified by `key_fingerprint`. Afterwards, we
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# still need to check that the key belongs to the committer.
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def valid_signature_blob?
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return false unless signature
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signature.verify(@signed_text)
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end
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def committer
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# Lookup by email because users can push verified commits that were made
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# by someone else. For example: Doing a rebase.
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strong_memoize(:committer) { User.find_by_any_email(@committer_email, confirmed: true) }
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end
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def signature
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strong_memoize(:signature) do
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::SSHData::Signature.parse_pem(@signature_text)
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rescue SSHData::DecodeError
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nil
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end
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end
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def key_fingerprint
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strong_memoize(:key_fingerprint) { signature&.public_key&.fingerprint }
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end
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def signed_by_key
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strong_memoize(:signed_by_key) do
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next unless key_fingerprint
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Key.find_by_fingerprint_sha256(key_fingerprint)
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end
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end
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end
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end
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end
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