fix(chromium): better default security and DX for allow / deny lists

pkg/modules/chromium/browser.go

@@ -42,8 +42,8 @@ type browserArguments struct {
 	hyphenDataDirPath        string
 
 	// Tasks specific.
-	allowList         *regexp2.Regexp
-	denyList          *regexp2.Regexp
+	allowList         []*regexp2.Regexp
+	denyList          []*regexp2.Regexp
 	clearCache        bool
 	clearCookies      bool
 	disableJavaScript bool
@@ -356,9 +356,10 @@ func (b *chromiumBrowser) do(ctx context.Context, logger *zap.Logger, url string
 	// the extra HTTP headers, if any.
 	// See https://github.com/gotenberg/gotenberg/issues/1011.
 	listenForEventRequestPaused(taskCtx, logger, eventRequestPausedOptions{
-		allowList:        b.arguments.allowList,
-		denyList:         b.arguments.denyList,
-		extraHttpHeaders: options.ExtraHttpHeaders,
+		allowList:           b.arguments.allowList,
+		denyList:            b.arguments.denyList,
+		allowedFilePrefixes: options.AllowedFilePrefixes,
+		extraHttpHeaders:    options.ExtraHttpHeaders,
 	})
 
 	var (

pkg/modules/chromium/chromium.go

@@ -172,6 +172,12 @@ type Options struct {
 	// OmitBackground hides the default white background and allows generating
 	// PDFs with transparency.
 	OmitBackground bool
+
+	// AllowedFilePrefixes restricts file:// sub-resource access to only these
+	// directory prefixes. Applied in listenForEventRequestPaused in addition
+	// to the global allow/deny lists. Set internally by route handlers, not
+	// via form data.
+	AllowedFilePrefixes []string
 }
 
 // EmulatedMediaFeature gathers the available entries for emulating a media
@@ -421,8 +427,8 @@ func (mod *Chromium) Descriptor() gotenberg.ModuleDescriptor {
 			fs.Bool("chromium-allow-file-access-from-files", false, "Allow file:// URIs to read other file:// URIs")
 			fs.String("chromium-host-resolver-rules", "", "Set custom mappings to the host resolver")
 			fs.String("chromium-proxy-server", "", "Set the outbound proxy server; this switch only affects HTTP and HTTPS requests")
-			fs.String("chromium-allow-list", "", "Set the allowed URLs for Chromium using a regular expression")
-			fs.String("chromium-deny-list", `^file:(?!//\/tmp/).*`, "Set the denied URLs for Chromium using a regular expression")
+			fs.StringSlice("chromium-allow-list", []string{}, "Set the allowed URLs for Chromium using regular expressions - supports multiple values")
+			fs.StringSlice("chromium-deny-list", []string{`^file:(?!//\/tmp/).*`}, "Set the denied URLs for Chromium using regular expressions - supports multiple values")
 			fs.Bool("chromium-clear-cache", false, "Clear Chromium cache between each conversion")
 			fs.Bool("chromium-clear-cookies", false, "Clear Chromium cookies between each conversion")
 			fs.Bool("chromium-disable-javascript", false, "Disable JavaScript")
@@ -469,8 +475,8 @@ func (mod *Chromium) Provision(ctx *gotenberg.Context) error {
 		wsUrlReadTimeout:         flags.MustDuration("chromium-start-timeout"),
 		hyphenDataDirPath:        hyphenDataDirPath,
 
-		allowList:         flags.MustRegexp("chromium-allow-list"),
-		denyList:          flags.MustRegexp("chromium-deny-list"),
+		allowList:         flags.MustRegexpSlice("chromium-allow-list"),
+		denyList:          flags.MustRegexpSlice("chromium-deny-list"),
 		clearCache:        flags.MustBool("chromium-clear-cache"),
 		clearCookies:      flags.MustBool("chromium-clear-cookies"),
 		disableJavaScript: flags.MustBool("chromium-disable-javascript"),

pkg/modules/chromium/events.go

@@ -24,7 +24,8 @@ import (
 )
 
 type eventRequestPausedOptions struct {
-	allowList, denyList *regexp2.Regexp
+	allowList, denyList []*regexp2.Regexp
+	allowedFilePrefixes []string
 	extraHttpHeaders    []ExtraHttpHeader
 }
 
@@ -58,6 +59,25 @@ func listenForEventRequestPaused(ctx context.Context, logger *zap.Logger, option
 					allow = false
 				}
 
+				// Additional restriction: if the sub-resource is a file:// URL
+				// and we have allowed file prefixes, restrict access to only
+				// those directories. This prevents cross-request file access
+				// in /tmp.
+				if allow && strings.HasPrefix(e.Request.URL, "file://") && len(options.allowedFilePrefixes) > 0 {
+					prefixMatch := false
+					for _, prefix := range options.allowedFilePrefixes {
+						if strings.HasPrefix(e.Request.URL, "file://"+prefix) {
+							prefixMatch = true
+							break
+						}
+					}
+
+					if !prefixMatch {
+						logger.Warn(fmt.Sprintf("'%s' is not within any allowed file prefix", e.Request.URL))
+						allow = false
+					}
+				}
+
 				cctx := chromedp.FromContext(ctx)
 				executorCtx := cdp.WithExecutor(ctx, cctx.Target)
 

pkg/modules/chromium/routes.go

@@ -512,6 +512,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			}
 
 			url := fmt.Sprintf("file://%s", inputPath)
+			options.AllowedFilePrefixes = []string{ctx.DirPath()}
 			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert HTML to PDF: %w", err)
@@ -542,6 +543,7 @@ func screenshotHtmlRoute(chromium Api) api.Route {
 			}
 
 			url := fmt.Sprintf("file://%s", inputPath)
+			options.AllowedFilePrefixes = []string{ctx.DirPath()}
 			err = screenshotUrl(ctx, chromium, url, options)
 			if err != nil {
 				return fmt.Errorf("HTML screenshot: %w", err)
@@ -598,6 +600,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("transform markdown file(s) to HTML: %w", err)
 			}
 
+			options.AllowedFilePrefixes = []string{ctx.DirPath()}
 			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert markdown to PDF: %w", err)
@@ -637,6 +640,7 @@ func screenshotMarkdownRoute(chromium Api) api.Route {
 				return fmt.Errorf("transform markdown file(s) to HTML: %w", err)
 			}
 
+			options.AllowedFilePrefixes = []string{ctx.DirPath()}
 			err = screenshotUrl(ctx, chromium, url, options)
 			if err != nil {
 				return fmt.Errorf("markdown screenshot: %w", err)