feat: allow customizing css filter and establish modified defaults

src/index.test.ts

@@ -1,3 +1,4 @@
+import { getDefaultCSSWhiteList } from "xss";
 import { Sanitizer } from "./index";
 
 // This file contains basic tests that validate the utility methods.
@@ -38,6 +39,20 @@ describe("Sanitizer", () => {
     "radarscope"
   ];
 
+  function getCSSOptions() {
+    const cssWhiteList = getDefaultCSSWhiteList();
+    cssWhiteList["flex"] = true;
+    cssWhiteList["flex-basis"] = true;
+    cssWhiteList["flex-direction"] = true;
+    cssWhiteList["flex-flow"] = true;
+    cssWhiteList["flex-grow"] = true;
+    cssWhiteList["flex-shrink"] = true;
+    cssWhiteList["flex-wrap"] = true;
+    cssWhiteList["line-height"] = true;
+    cssWhiteList["overflow"] = true;
+    return { whiteList: cssWhiteList };
+  }
+
   test("creates the Sanitizer object and extends options appropriately", () => {
     // Test with no arguments
     const sanitizer1 = new Sanitizer();
@@ -46,6 +61,7 @@ describe("Sanitizer", () => {
       defaultSanitizer1.arcgisFilterOptions
     );
     defaultOptions1.whiteList = defaultSanitizer1.arcgisWhiteList;
+    defaultOptions1.css = getCSSOptions();
     expect(sanitizer1.xssFilterOptions).toEqual(defaultOptions1);
 
     // Extending the defaults
@@ -58,6 +74,7 @@ describe("Sanitizer", () => {
     filterOptions2.whiteList = defaultSanitizer2.arcgisWhiteList;
     filterOptions2.whiteList.blink = [];
     filterOptions2.allowCommentTag = false;
+    filterOptions2.css = getCSSOptions();
     expect(sanitizer2.xssFilterOptions).toEqual(filterOptions2);
 
     // Passing an empty whitelist
@@ -68,11 +85,25 @@ describe("Sanitizer", () => {
       defaultSanitizer3.arcgisFilterOptions
     );
     defaultOptions3.whiteList = defaultSanitizer3.arcgisWhiteList;
+    defaultOptions3.css = getCSSOptions();
     expect(sanitizer3.xssFilterOptions).toEqual(defaultOptions3);
 
     // Test overriding defaults
     const sanitizer4 = new Sanitizer({ whiteList: { a: [] } });
     expect(sanitizer4.xssFilterOptions).toEqual({ whiteList: { a: [] } });
+
+    // Extending the CSS defaults
+    const sanitizer5 = new Sanitizer({ css: { whiteList: { "line-height": false, "align-items": true } } }, true);
+    const defaultSanitizer5 = new Sanitizer();
+    const defaultOptions5 = Object.create(
+      defaultSanitizer5.arcgisFilterOptions
+    );
+    defaultOptions5.css = getCSSOptions();
+    defaultOptions5.css.whiteList["line-height"] = false;
+    defaultOptions5.css.whiteList["align-items"] = true;
+    expect((sanitizer5.xssFilterOptions.css as any).whiteList["line-height"]).toBeFalsy();
+    expect((sanitizer5.xssFilterOptions.css as any).whiteList["align-items"]).toBeTruthy();
+    expect(sanitizer5.xssFilterOptions).toEqual(defaultOptions5);
   });
 
   test("sanitizes a value", () => {
@@ -451,6 +482,7 @@ describe("Sanitizer", () => {
     const strippedVideoSrc = "<video controls>";
     const fontFace = `<font face="Arial">Text content</font>`;
     const figure = `<figure style="background-color:blue;background-image:url("javascript:alert(\"xss\")";" onerror="alert(1)" onclick="javascript:alert(\"xss\")"><figcaption style="background-color:red;background-image:url("javascript:alert(\"xss\")";" onerror="alert(1)" onclick="javascript:alert(\"xss\")">Figure Caption</figcaption></figure>`;
+    const flexContainer = `<div style="flex:1 1 0%; flex-direction:column;">Flex container</div>`;
     const elementsWithStyle = ["a", "img", "span", "div", "font", "table", "tr", "th", "td", "p", "dd", "dl", "dt", "h1", "h2", "h3", "h4", "h5", "h6", "sub", "sup"];
 
     const sanitizer = new Sanitizer();
@@ -466,6 +498,7 @@ describe("Sanitizer", () => {
     expect(sanitizer.sanitize(video)).toBe(video);
     expect(sanitizer.sanitize(stripVideoSrc)).toBe(strippedVideoSrc);
     expect(sanitizer.sanitize(fontFace)).toBe(fontFace);
+    expect(sanitizer.sanitize(flexContainer)).toBe(flexContainer);
     expect(sanitizer.sanitize(figure)).toBe(
       `<figure style="background-color:blue;"><figcaption style="background-color:red;">Figure Caption</figcaption></figure>`
     );
@@ -585,4 +618,21 @@ describe("Sanitizer", () => {
     expect(sanitizer.sanitize(includesAllowed)).toBe(sanitizedAllowed);
   });
 
+  test("css overrides", () => {
+    const sanitizer = new Sanitizer();
+    const flexProperties = [
+      "flex:1 1 0%;",
+      "flex-basis:0.25rem;",
+      "flex-direction:row;",
+      "flex-flow:row wrap;",
+      "flex-grow:1;",
+      "flex-shrink:1;",
+      "flex-wrap:wrap;",
+    ];
+    flexProperties.forEach((prop) => {
+      const value = `<div style="${prop}">Flex property test</div>`;
+      expect(sanitizer.sanitize(value)).toBe(value);
+    });
+  });
+
 });

src/index.ts

@@ -25,6 +25,13 @@ export interface IWhiteList extends XSS.IWhiteList {
   source?: string[];
 }
 
+export interface ICSSFilter extends XSS.ICSSFilter {
+  whiteList: ICSSWhiteList;
+}
+export interface ICSSWhiteList {
+  [key: string]: boolean;
+}
+
 /** Options to apply to sanitize method */
 export interface ISanitizeOptions {
   /* Don't convert undefined to null */
@@ -120,6 +127,17 @@ export class Sanitizer {
       "width",
     ],
   };
+  private readonly arcgisCSSWhiteListOverrides: ICSSWhiteList = {
+    "flex": true,
+    "flex-basis": true,
+    "flex-direction": true,
+    "flex-flow": true,
+    "flex-grow": true,
+    "flex-shrink": true,
+    "flex-wrap": true,
+    "line-height": true,
+    "overflow": true
+  };
   public readonly allowedProtocols: string[] = [
     "http",
     "https",
@@ -186,15 +204,27 @@ export class Sanitizer {
       // Override the defaults
       xssFilterOptions = filterOptions;
     } else if (filterOptions && extendDefaults) {
+      const cssWhiteList = this._getArcGISCSSWhiteList();
+
       // Extend the defaults
       xssFilterOptions = Object.create(this.arcgisFilterOptions);
+      xssFilterOptions.css = { whiteList: cssWhiteList };
       Object.keys(filterOptions).forEach((key) => {
         if (key === "whiteList") {
           // Extend the whitelist by concatenating arrays
           xssFilterOptions.whiteList = this._extendObjectOfArrays([
             this.arcgisWhiteList,
             filterOptions.whiteList || {},
           ]);
+        } else if (key === "css") {
+          const cssExtensions = (filterOptions.css as ICSSFilter).whiteList;
+          if (cssExtensions != null && filterOptions.css instanceof Object) {
+            Object.keys(cssExtensions).forEach(
+              (attr) =>
+                ((xssFilterOptions.css as ICSSFilter).whiteList[attr] =
+                  cssExtensions[attr])
+            );
+          }
         } else {
           xssFilterOptions[key] = filterOptions[key];
         }
@@ -203,6 +233,7 @@ export class Sanitizer {
       // Only use the defaults
       xssFilterOptions = Object.create(this.arcgisFilterOptions);
       xssFilterOptions.whiteList = this.arcgisWhiteList;
+      xssFilterOptions.css = { whiteList: this._getArcGISCSSWhiteList() };
     }
 
     this.xssFilterOptions = xssFilterOptions;
@@ -353,6 +384,14 @@ export class Sanitizer {
     });
   }
 
+  private _getArcGISCSSWhiteList() {
+    const cssWhiteList = xss.getDefaultCSSWhiteList();
+    Object.keys(this.arcgisCSSWhiteListOverrides).forEach((key) => {
+      cssWhiteList[key] = this.arcgisCSSWhiteListOverrides[key];
+    });
+    return cssWhiteList;
+  }
+
   /**
    * Extends an object of arrays by by concatenating arrays of the same object
    * keys. If the if the previous key's value is not an array, the next key's