96 lines
3.1 KiB
Ruby
96 lines
3.1 KiB
Ruby
# frozen_string_literal: true
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# The method `filename` must be defined in classes that mix in this module.
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#
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# This module is intended to be used as a helper and not a security gate
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# to validate that a file is safe, as it identifies files only by the
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# file extension and not its actual contents.
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#
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# An example useage of this module is in `FileMarkdownLinkBuilder` that
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# renders markdown depending on a file name.
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#
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# We use Workhorse to detect the real extension when we serve files with
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# the `SendsBlob` helper methods, and ask Workhorse to set the content
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# type when it serves the file:
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# https://gitlab.com/gitlab-org/gitlab/blob/33e5955/app/helpers/workhorse_helper.rb#L48.
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#
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# Because Workhorse has access to the content when it is downloaded, if
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# the type/extension doesn't match the real type, we adjust the
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# `Content-Type` and `Content-Disposition` to the one we get from the detection.
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module Gitlab
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module FileTypeDetection
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SAFE_IMAGE_EXT = %w[png jpg jpeg gif bmp tiff ico webp].freeze
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SAFE_IMAGE_FOR_SCALING_EXT = %w[png jpg jpeg].freeze
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PDF_EXT = 'pdf'
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# We recommend using the .mp4 format over .mov. Videos in .mov format can
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# still be used but you really need to make sure they are served with the
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# proper MIME type video/mp4 and not video/quicktime or your videos won't play
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# on IE >= 9.
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# http://archive.sublimevideo.info/20150912/docs.sublimevideo.net/troubleshooting.html
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SAFE_VIDEO_EXT = %w[mp4 m4v mov webm ogv].freeze
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SAFE_AUDIO_EXT = %w[mp3 oga ogg spx wav].freeze
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# These extension types can contain dangerous code and should only be embedded inline with
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# proper filtering. They should always be tagged as "Content-Disposition: attachment", not "inline".
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DANGEROUS_IMAGE_EXT = %w[svg].freeze
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DANGEROUS_VIDEO_EXT = [].freeze # None, yet
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DANGEROUS_AUDIO_EXT = [].freeze # None, yet
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def self.extension_match?(filename, extensions)
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return false unless filename.present?
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extension = File.extname(filename).delete('.')
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extensions.include?(extension.downcase)
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end
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def image?
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extension_match?(SAFE_IMAGE_EXT)
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end
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# For the time being, we restrict image scaling requests to the most popular and safest formats only,
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# which are JPGs and PNGs. See https://gitlab.com/gitlab-org/gitlab/-/issues/237848 for more info.
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def image_safe_for_scaling?
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extension_match?(SAFE_IMAGE_FOR_SCALING_EXT)
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end
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def video?
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extension_match?(SAFE_VIDEO_EXT)
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end
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def audio?
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extension_match?(SAFE_AUDIO_EXT)
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end
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def pdf?
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extension_match?([PDF_EXT])
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end
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def embeddable?
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image? || video? || audio?
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end
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def dangerous_image?
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extension_match?(DANGEROUS_IMAGE_EXT)
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end
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def dangerous_video?
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extension_match?(DANGEROUS_VIDEO_EXT)
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end
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def dangerous_audio?
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extension_match?(DANGEROUS_AUDIO_EXT)
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end
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def dangerous_embeddable?
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dangerous_image? || dangerous_video? || dangerous_audio?
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end
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private
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def extension_match?(extensions)
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::Gitlab::FileTypeDetection.extension_match?(filename, extensions)
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end
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end
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end
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