53 lines
1.8 KiB
Elixir
53 lines
1.8 KiB
Elixir
defmodule ToweropsWeb.Plugs.SecurityHeaders do
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@moduledoc """
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Adds security headers to all responses in production.
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Headers added:
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- Content-Security-Policy: Restricts resource loading to prevent XSS
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- X-Frame-Options: Prevents clickjacking attacks
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- X-Content-Type-Options: Prevents MIME type sniffing
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- Referrer-Policy: Controls referrer information leakage
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These headers are only applied in production to avoid interfering with
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development tools like LiveReload.
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"""
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import Plug.Conn
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def init(opts), do: opts
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def call(conn, _opts) do
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if Application.get_env(:towerops, :env) == :prod do
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conn
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|> put_resp_header("content-security-policy", csp_header())
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|> put_resp_header("x-frame-options", "SAMEORIGIN")
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|> put_resp_header("x-content-type-options", "nosniff")
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|> put_resp_header("referrer-policy", "strict-origin-when-cross-origin")
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else
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conn
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end
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end
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# Content Security Policy
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# - default-src 'self': Only load resources from same origin by default
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# - script-src: Allow inline scripts (needed for LiveView), eval, and self
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# - style-src: Allow inline styles (needed for Tailwind), unsafe-hashes, and self
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# - img-src: Allow images from self, data URIs, and https
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# - font-src: Allow fonts from self and data URIs
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# - connect-src: Allow WebSocket connections for LiveView
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# - frame-ancestors: Same as X-Frame-Options (SAMEORIGIN)
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defp csp_header do
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Enum.join(
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[
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"default-src 'self'",
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"script-src 'self' 'unsafe-inline' 'unsafe-eval'",
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"style-src 'self' 'unsafe-inline' 'unsafe-hashes'",
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"img-src 'self' data: https:",
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"font-src 'self' data:",
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"connect-src 'self' ws: wss:",
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"frame-ancestors 'self'"
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],
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"; "
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)
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end
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end
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