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https://github.com/basecamp/once-campfire.git
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Jeremy Daer
27f7b8a9b0
A request for several byte ranges gets a 206 multipart/byteranges whose
boundary the client needs to split the body. Rewriting it to
octet-stream lost the boundary. No browser runs that type as a script,
so it passes through.
(cherry picked from commit 9c37f41ff6)
37 lines
1.7 KiB
Ruby
37 lines
1.7 KiB
Ruby
# Uploaded files are served from this origin, so under script-src 'self' an
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# upload served with any JavaScript MIME type would run as one of our scripts.
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# Browsers accept sixteen spellings of that type, and Disk URLs sign the type
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# they were minted with, so a list of types to refuse can't cover old links.
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# Instead, anything Active Storage serves that isn't plainly media goes out as
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# a download, whatever its URL says. A multi-range response keeps its
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# multipart/byteranges type and boundary, which no browser runs as a script.
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# Only reads are touched: uploading
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# (direct upload JSON, Disk PUT) answers in its own types.
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#
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# Accepted on upgrade: a cache that stored an upload under a script type
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# before this guard shipped can still serve it as one until the entry expires.
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# For Disk URLs that's up to an hour (config/initializers/active_storage.rb).
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# Blob proxy URLs are cached publicly and as immutable for a hundred years
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# (Rails' http_cache_forever), so a copy a browser or a shared cache took that
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# way doesn't expire. Revalidation doesn't help, since a 304 carries no
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# content type.
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class UploadedScriptGuard
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SERVABLE = %r{\A(image|video|audio)/|\A(application/pdf|application/octet-stream|text/plain|multipart/byteranges)\z}
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def initialize(app)
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@app = app
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end
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def call(env)
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status, headers, body = @app.call(env)
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if env["REQUEST_METHOD"].in?(%w[ GET HEAD ]) && env["PATH_INFO"].start_with?("#{ActiveStorage.routes_prefix}/") && (type = headers["content-type"])
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headers["content-type"] = ActiveStorage.binary_content_type unless type.split(";").first.strip.downcase.match?(SERVABLE)
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end
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[ status, headers, body ]
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end
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end
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Rails.application.config.middleware.use UploadedScriptGuard
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