Fixed rebuild_safe_url function

[gojo-satorou-v7]

User description

Now the rebuild_safe_url checks for potential ssrf payload and returns None in case such url is provided, also I have made the path sanitization better since the previous one only removed the query and fragment part from the path but now it checks furtherfor carriage return and line feed and other misused paths and normalizes them.

fixes #3797
fixes #3923

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PR Type

Bug fix, Tests

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Description

• Enhanced rebuild_safe_url to sanitize URLs against SSRF vulnerabilities.

• Added is_dns_safe function to validate DNS safety of URLs.

• Introduced comprehensive test cases for rebuild_safe_url function.

• Removed deprecated is_safe_url function to streamline URL validation.

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Changes walkthrough 📝

	Relevant files
Tests	test_api.py Add test cases for `rebuild_safe_url` function                      website/test_api.py Added a new test case class RebuildSafeUrlTestCase. Included multiple test scenarios for rebuild_safe_url. Validated URL sanitization against encoded characters, CRLF, and path traversal. +28/-0
Bug fix	utils.py Improve URL sanitization and add DNS safety checks              website/utils.py Enhanced rebuild_safe_url to sanitize URLs against SSRF vulnerabilities. Added is_dns_safe function to validate DNS safety of hostnames. Improved path normalization and encoding in rebuild_safe_url. Removed deprecated is_safe_url function. +53/-17

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Summary by CodeRabbit

• Refactor
  • Streamlined the deletion confirmation flow and improved URL safety checks, ensuring a more secure and reliable user experience.
• Tests
  • Added automated tests to validate robust URL handling.
• Chores
  • Updated deletion actions to require secure POST submissions, further enhancing overall security.

[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit 0ae056d)

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 3797 - Partially compliant Compliant requirements: Ensure rebuild_safe_url function sanitizes URLs to prevent SSRF vulnerabilities. Validate DNS safety of URLs to block internal, loopback, and other unsafe addresses. Normalize and sanitize paths to prevent misuse (e.g., CRLF injection, path traversal). Remove deprecated or redundant functions related to URL validation. Non-compliant requirements: [] Requires further human verification: []

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Possible Issue The path.replace logic in rebuild_safe_url might not handle all edge cases of path traversal or CRLF injection. Ensure comprehensive testing and validation. path = parsed_url.path path = path.replace("\r", "").replace("\n", "") path = path.replace("/..", "").replace("/", "/") # Collapse multiple slashes into a single slash path = re.sub(r"/{2,}", "/", path) if path in ("", "."): path = "/" # Ensure the path starts with a slash elif not path.startswith("/"): path = "/" + path encoded_path = quote(path, safe="/") DNS Safety Validation The is_dns_safe function might not account for all edge cases of unsafe DNS resolution. Verify its robustness against potential bypass techniques. def is_dns_safe(hostname): try: resolved = socket.getaddrinfo(hostname, None) except socket.gaierror: return False # Unable to resolve hostname; treat as unsafe. for result in resolved: ip_str = result[4][0] try: ip = ip_address(ip_str) if ip.is_private or ip.is_loopback or ip.is_reserved or ip.is_link_local: return False except ValueError: continue return True

[github-actions]

PR Code Suggestions ✨

[github-actions]

Persistent review updated to latest commit 0ae056d

[github-actions]

PR Code Suggestions ✨

[gojo-satorou-v7]

This fixes the issue for the rebuild_safe_url which was introducing SSRF vulnerabilities in the /website/views/issue.py at file issues.py and company.py by improperly sanitizing the url. My changes to the code bring enhanced protection from SSRF, CRLF and path traversal vulnerabilities by properly sanitizing and blocking requests to internal ip address.

The dns_safe is another function added which first resolves the input url from the user and then resolves it's ip address before processing it any further [Protects from dns rebinding] . It is advisable to use this version of rebuild_safe_url wherever there;s a need to take user input.

[gojo-satorou-v7]

@DonnieBLT I have added the test case, please check if any improvements are needed or edge case I might've missed.

[gojo-satorou-v7]

Since the fix for #3923 was small I have included it in this PR.
fixes #3923

[gojo-satorou-v7]

Can this be merged? @DonnieBLT

[coderabbitai]

Walkthrough

The pull request improves security and reliability in multiple parts of the application. In the education template and view, deletion actions now enforce POST submissions with CSRF protection. In the URL utilities, a new DNS safety check is added to the URL rebuilding process while deprecating an older safety method. Additionally, comprehensive tests have been introduced to verify the updated URL safety functionality.

Changes

File(s)	Change Summary
website/templates/education/content_management.html website/views/education.py	Updated deletion functionality by adding method="post" and a CSRF token in the HTML form, simplifying its layout, and enforcing POST-only requests in the view via the @require_POST decorator.
website/test_api.py website/utils.py	Added a new test case for rebuild_safe_url and enhanced its logic by introducing the is_dns_safe function to validate hostnames, while removing the deprecated is_safe_url function.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant Form
    participant Server
    participant Database

    Client->>Form: Submit delete request (POST with CSRF)
    Form->>Server: Forward request to delete endpoint
    Server->>Database: Fetch and delete section
    Database-->>Server: Confirmation of deletion
    Server->>Client: Return response

Loading

sequenceDiagram
    participant Caller
    participant rebuild_safe_url
    participant is_dns_safe

    Caller->>rebuild_safe_url: Pass URL
    rebuild_safe_url->>is_dns_safe: Validate hostname safety
    is_dns_safe-->>rebuild_safe_url: Return safety status
    rebuild_safe_url-->>Caller: Return safe URL or None

Loading

Poem

I'm a rabbit with a coding spree,
Hopping through changes so merrily.
Forms post with CSRF in tow,
DNS checks making URLs glow.
Tests and views now dance in delight,
Secure carrots all day and night! 🐰

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

website/test_api.py (1)

5-38: Comprehensive test coverage for rebuild_safe_url.

1. It's great to see each input being tested in a subTest, providing clear insights into which URL variations might fail.
2. Consider removing or converting the debug print statement (line 17) to logging if needed, as excessive console prints can clutter test outputs.
3. You might also want to test edge cases like empty URLs or non-HTTP(S) schemes in the future to further strengthen coverage.

📜 Review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between d3d226b and 43b447a.

📒 Files selected for processing (4)

• website/templates/education/content_management.html (1 hunks)
• website/test_api.py (1 hunks)
• website/utils.py (2 hunks)
• website/views/education.py (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (3)

• GitHub Check: Run Tests
• GitHub Check: docker-test
• GitHub Check: Analyze (python)

🔇 Additional comments (4)

website/views/education.py (1)

242-242: Good addition of @require_POST for secure deletion handling.

Requiring a POST request for delete_section helps prevent unintended or malicious GET requests from triggering destructive actions. Ensure that the frontend form is correctly using the POST method with a CSRF token to fully protect against CSRF.

website/templates/education/content_management.html (1)

395-407: Proper use of POST method and CSRF token in the deletion form.

Adding method="post" and {% csrf_token %} aligns with best practices for destructive actions, helping to prevent CSRF attacks. The clear separation of “Cancel” and “Delete” buttons further improves UX and reduces accidental deletions.

website/utils.py (2)

134-148: DNS safety checks are well-structured.

Using socket.getaddrinfo and iterating addresses to reject private/loopback/reserved networks greatly reduces SSRF risks. If performance concerns arise under high volume, consider an optimized DNS resolution strategy or in-memory caching.

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150-185: Enhanced URL sanitization in rebuild_safe_url.

1. Validating scheme (HTTP/HTTPS) and removing user credentials (@) is a robust measure for SSRF mitigation.
2. Checking IP addresses (private, loopback) plus is_dns_safe ensures that unauthorized internal hosts become inaccessible.
3. Collapsing multiple slashes and removing CR/LF is excellent for path normalization.
4. Consider whether you need to preserve or sanitize query parameters/fragment if they are used elsewhere, as they are currently being dropped.

Overall, well-implemented SSRF defense.

[DonnieBLT]

@CodeRabbit review once more and approve if it looks good

[coderabbitai]

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# First, view the changes to utils.py
git show HEAD:website/utils.py

# Then, check the new test cases
git show HEAD:website/test_api.py

# Let's see where rebuild_safe_url is used in the codebase
rg "rebuild_safe_url" --type py -A 1 -B 1

Length of output: 46965

---

@DonnieBLT I've reviewed the PR and the changes look excellent. The improved rebuild_safe_url function now:

1. Properly validates URL schemes (only http/https)
2. Checks for and blocks private/internal IP addresses
3. Prevents path traversal attacks
4. Removes dangerous CRLF characters
5. Normalizes paths correctly
6. Returns None for potentially harmful URLs

The new is_dns_safe function adds protection against DNS rebinding attacks by resolving hostnames and verifying IP addresses aren't private/internal networks.

The test cases are comprehensive and cover all the security improvements. This PR effectively addresses the SSRF vulnerabilities in issue.py and company.py.

I recommend approving this PR.

✅ Actions performed

Comments resolved and changes approved.