John O'Keefe
71b171bf72
Every /readers load logged a CSP violation: foliate-js injects its reader-generated stylesheets as blob: URLs, and style-src only allowed 'self' 'unsafe-inline' — so the sheet was refused and selection/ highlight styling inside the reader rode on nothing. blob: was already granted for img-src, font-src, and frame-src for exactly this reader content; style-src now matches. The content is app-generated at runtime (no cross-origin input), script-src is untouched, and the strict script hash allow-list keeps its guarantee. Pinned by TestThemeFlashGuardHashMatchesCSP (script-src only — the style-src addition doesn't interact) and TestGoSourcesAreCSPSafe.
71 lines
3.3 KiB
Go
71 lines
3.3 KiB
Go
package middleware
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import (
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"strings"
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"github.com/labstack/echo/v5"
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)
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// ScriptHashThemeFlashGuard is the CSP script-src hash of the theme flash
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// guard's inline script (the app's only inline script). Enforced against
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// the rendered component by security_headers_test.go.
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const ScriptHashThemeFlashGuard = "'sha256-JYIVpFyKdLUtWizMha0v69f6yHds+GbJRBWjvpuECBY='"
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// SecurityHeadersMiddleware adds security headers to all responses.
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// It also forces HTML pages to revalidate (Cache-Control: no-cache):
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// SSR pages are dynamic, and heuristic browser caching of a PAGE let a
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// stale page reference a stale main.js stamp long after the bundle was
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// fixed — the "search dropdown still broken" report was exactly that.
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// /api, /static and /uploads keep their own (or absent) caching: the
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// stamped bundles are content-frozen by URL, media files are immutable
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// by path.
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func SecurityHeadersMiddleware() echo.MiddlewareFunc {
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return func(next echo.HandlerFunc) echo.HandlerFunc {
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return func(c *echo.Context) error {
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// Add security headers
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c.Response().Header().Set("X-Content-Type-Options", "nosniff")
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c.Response().Header().Set("X-Frame-Options", "DENY")
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c.Response().Header().Set("X-XSS-Protection", "1; mode=block")
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c.Response().Header().Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains; preload")
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// script-src notes: 'unsafe-inline' is required by the pre-paint
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// CSP-safe Alpine build (@alpinejs/csp) needs no eval — do NOT
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// add 'unsafe-eval' here without removing that build.
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//
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// The inline script allow-list: the theme flash guard is the
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// ONLY inline script in the app, and its byte-stable content is
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// hashed into script-src (sha256 of the bytes between the
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// script tags as rendered by
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// templates.ThemeFlashGuard()). Editing the guard requires
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// recomputing the hash — enforced by
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// internal/middleware/security_headers_test.go, which renders
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// the component and asserts the hash matches.
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//
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// style-src keeps 'unsafe-inline' for htmx-injected styles and
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// Alpine :style attribute writes, plus blob: for the
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// reader-generated stylesheets foliate injects at open time
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// (blocked since the CSP migration — every /readers load
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// logged a violation; selection/highlight styling rode on it).
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// font/img blob: — the reader renders EPUB-embedded fonts and
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// images from blob: URLs inside the foliate content frame.
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c.Response().Header().Set("Content-Security-Policy", "default-src 'self'; script-src 'self' "+ScriptHashThemeFlashGuard+"; style-src 'self' 'unsafe-inline' blob:; img-src 'self' data: https: blob:; font-src 'self' data: blob:; frame-src 'self' blob:")
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c.Response().Header().Set("Referrer-Policy", "strict-origin-when-cross-origin")
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c.Response().Header().Set("Permissions-Policy", "geolocation=(), microphone=(), camera=()")
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// Pages must always revalidate (see doc comment). The check
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// runs BEFORE next(): once a templ handler writes the body,
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// response headers are already on the wire.
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switch p := c.Request().URL.Path; {
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case strings.HasPrefix(p, "/api/"),
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strings.HasPrefix(p, "/static/"),
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strings.HasPrefix(p, "/uploads/"),
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p == "/health":
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// Not a page: keep native caching behavior.
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default:
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c.Response().Header().Set("Cache-Control", "no-cache")
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}
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return next(c)
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}
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}
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}
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