[7.x] Support deep links inside of RelayState for SAML IdP initiate…

…d login. (#69773)

# Conflicts:
#	x-pack/plugins/security/server/authentication/providers/saml.test.ts
#	x-pack/plugins/security/server/authentication/providers/saml.ts
#	x-pack/plugins/security/server/routes/authentication/saml.ts

* Fix eslint warning.

x-pack/dev-tools/jest/setup/polyfills.js

@@ -17,5 +17,7 @@ const MutationObserver = require('mutation-observer');
 Object.defineProperty(window, 'MutationObserver', { value: MutationObserver });
 
 require('whatwg-fetch');
-const URL = { createObjectURL: () => '' };
-Object.defineProperty(window, 'URL', { value: URL });
+
+if (!global.URL.hasOwnProperty('createObjectURL')) {
+  Object.defineProperty(global.URL, 'createObjectURL', { value: () => '' });
+}

x-pack/plugins/security/common/is_internal_url.test.ts

@@ -0,0 +1,88 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { isInternalURL } from './is_internal_url';
+
+describe('isInternalURL', () => {
+  describe('with basePath defined', () => {
+    const basePath = '/iqf';
+
+    it('should return `true `if URL includes hash fragment', () => {
+      const href = `${basePath}/app/kibana#/discover/New-Saved-Search`;
+      expect(isInternalURL(href, basePath)).toBe(true);
+    });
+
+    it('should return `false` if URL includes a protocol/hostname', () => {
+      const href = `https://example.com${basePath}/app/kibana`;
+      expect(isInternalURL(href, basePath)).toBe(false);
+    });
+
+    it('should return `false` if URL includes a port', () => {
+      const href = `http://localhost:5601${basePath}/app/kibana`;
+      expect(isInternalURL(href, basePath)).toBe(false);
+    });
+
+    it('should return `false` if URL does not specify protocol', () => {
+      const hrefWithTwoSlashes = `/${basePath}/app/kibana`;
+      expect(isInternalURL(hrefWithTwoSlashes)).toBe(false);
+
+      const hrefWithThreeSlashes = `//${basePath}/app/kibana`;
+      expect(isInternalURL(hrefWithThreeSlashes)).toBe(false);
+    });
+
+    it('should return `true` if URL starts with a basepath', () => {
+      for (const href of [basePath, `${basePath}/`, `${basePath}/login`, `${basePath}/login/`]) {
+        expect(isInternalURL(href, basePath)).toBe(true);
+      }
+    });
+
+    it('should return `false` if URL does not start with basePath', () => {
+      for (const href of [
+        '/notbasepath/app/kibana',
+        `${basePath}_/login`,
+        basePath.slice(1),
+        `${basePath.slice(1)}/app/kibana`,
+      ]) {
+        expect(isInternalURL(href, basePath)).toBe(false);
+      }
+    });
+
+    it('should return `true` if relative path does not escape base path', () => {
+      const href = `${basePath}/app/kibana/../../management`;
+      expect(isInternalURL(href, basePath)).toBe(true);
+    });
+
+    it('should return `false` if relative path escapes base path', () => {
+      const href = `${basePath}/app/kibana/../../../management`;
+      expect(isInternalURL(href, basePath)).toBe(false);
+    });
+  });
+
+  describe('without basePath defined', () => {
+    it('should return `true `if URL includes hash fragment', () => {
+      const href = '/app/kibana#/discover/New-Saved-Search';
+      expect(isInternalURL(href)).toBe(true);
+    });
+
+    it('should return `false` if URL includes a protocol/hostname', () => {
+      const href = 'https://example.com/app/kibana';
+      expect(isInternalURL(href)).toBe(false);
+    });
+
+    it('should return `false` if URL includes a port', () => {
+      const href = 'http://localhost:5601/app/kibana';
+      expect(isInternalURL(href)).toBe(false);
+    });
+
+    it('should return `false` if URL does not specify protocol', () => {
+      const hrefWithTwoSlashes = `//app/kibana`;
+      expect(isInternalURL(hrefWithTwoSlashes)).toBe(false);
+
+      const hrefWithThreeSlashes = `///app/kibana`;
+      expect(isInternalURL(hrefWithThreeSlashes)).toBe(false);
+    });
+  });
+});

x-pack/plugins/security/common/is_internal_url.ts

@@ -0,0 +1,38 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { parse } from 'url';
+
+export function isInternalURL(url: string, basePath = '') {
+  const { protocol, hostname, port, pathname } = parse(
+    url,
+    false /* parseQueryString */,
+    true /* slashesDenoteHost */
+  );
+
+  // We should explicitly compare `protocol`, `port` and `hostname` to null to make sure these are not
+  // detected in the URL at all. For example `hostname` can be empty string for Node URL parser, but
+  // browser (because of various bwc reasons) processes URL differently (e.g. `///abc.com` - for browser
+  // hostname is `abc.com`, but for Node hostname is an empty string i.e. everything between schema (`//`)
+  // and the first slash that belongs to path.
+  if (protocol !== null || hostname !== null || port !== null) {
+    return false;
+  }
+
+  if (basePath) {
+    // Now we need to normalize URL to make sure any relative path segments (`..`) cannot escape expected
+    // base path. We can rely on `URL` with a localhost to automatically "normalize" the URL.
+    const normalizedPathname = new URL(String(pathname), 'https://localhost').pathname;
+    return (
+      // Normalized pathname can add a leading slash, but we should also make sure it's included in
+      // the original URL too
+      pathname?.startsWith('/') &&
+      (normalizedPathname === basePath || normalizedPathname.startsWith(`${basePath}/`))
+    );
+  }
+
+  return true;
+}

x-pack/plugins/security/common/parse_next.ts

@@ -5,6 +5,7 @@
  */
 
 import { parse } from 'url';
+import { isInternalURL } from './is_internal_url';
 
 export function parseNext(href: string, basePath = '') {
   const { query, hash } = parse(href, true);
@@ -20,23 +21,8 @@ export function parseNext(href: string, basePath = '') {
   }
 
   // validate that `next` is not attempting a redirect to somewhere
-  // outside of this Kibana install
-  const { protocol, hostname, port, pathname } = parse(
-    next,
-    false /* parseQueryString */,
-    true /* slashesDenoteHost */
-  );
-
-  // We should explicitly compare `protocol`, `port` and `hostname` to null to make sure these are not
-  // detected in the URL at all. For example `hostname` can be empty string for Node URL parser, but
-  // browser (because of various bwc reasons) processes URL differently (e.g. `///abc.com` - for browser
-  // hostname is `abc.com`, but for Node hostname is an empty string i.e. everything between schema (`//`)
-  // and the first slash that belongs to path.
-  if (protocol !== null || hostname !== null || port !== null) {
-    return `${basePath}/`;
-  }
-
-  if (!String(pathname).startsWith(basePath)) {
+  // outside of this Kibana install.
+  if (!isInternalURL(next, basePath)) {
     return `${basePath}/`;
   }