fix(web): restrict postMessage targetOrigin from wildcard to specific origins

[xuwei95]

Summary

This PR fixes a security vulnerability (CVE) related to postMessage usage in the web frontend. The changes restrict the targetOrigin parameter from wildcard (*) to specific origins.

Fixes #30723

Changes

1. Embedded Chatbot (web/app/components/base/chat/embedded-chatbot/header/index.tsx):

   • Changed from postMessage(..., '*') to using document.referrer to determine parent origin
   • Falls back to '*' only if referrer is unavailable

2. OAuth Hook (web/hooks/use-oauth.ts):

   • Changed from postMessage(..., '*') to using window.opener.origin
   • Falls back to '*' only if opener origin is unavailable

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint and make type-check (backend) and cd web && npx lint-staged (frontend) to appease the lint gods

[gemini-code-assist]

Summary of Changes

Hello @xuwei95, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the security posture of the web frontend by tightening the targetOrigin parameter used in postMessage communications. By moving away from a broad wildcard target to more specific origin validation based on document.referrer or window.opener.origin, the changes mitigate potential cross-site scripting (XSS) and data leakage risks, ensuring that messages are only sent to trusted recipients.

Highlights

• Security Fix: This pull request addresses a security vulnerability (CVE) by restricting the targetOrigin parameter in postMessage calls from a wildcard (*) to specific, validated origins.
• Embedded Chatbot Update: In web/app/components/base/chat/embedded-chatbot/header/index.tsx, the postMessage call now dynamically determines the targetOrigin using document.referrer, falling back to * only if the referrer is unavailable.
• OAuth Hook Enhancement: The web/hooks/use-oauth.ts file has been updated to use window.opener.origin as the targetOrigin for postMessage calls, providing a more secure communication channel and falling back to * if the opener origin is not accessible.

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[gemini-code-assist]

Code Review

This pull request is a good step towards enhancing security by restricting the targetOrigin in postMessage calls. The changes correctly identify the need to move away from a wildcard origin. However, the implementation in both modified files includes a fallback to '*', which could re-introduce the security vulnerability this PR aims to fix. My review includes suggestions to eliminate this fallback, particularly in use-oauth.ts where sensitive data is handled, and to improve the robustness of the origin detection in the embedded chatbot header.

[crazywoola]

Please link an issue in the description :)