disallow javascript: URI in the repository description

- Fixes an XSS that was introduced in
https://codeberg.org/forgejo/forgejo/pulls/1433
- This XSS allows for `href`s in anchor elements to be set to a
`javascript:` uri in the repository description, which would upon
clicking (and not upon loading) the anchor element execute the specified
javascript in that uri.
- [`AllowStandardURLs`](https://pkg.go.dev/github.com/microcosm-cc/bluemonday#Policy.AllowStandardURLs) is now called for the repository description
policy, which ensures that URIs in anchor elements are `mailto:`,
`http://` or `https://` and thereby disallowing the `javascript:` URI.
It also now allows non-relative links and sets `rel="nofollow"` on
anchor elements.
- Unit test added.

(cherry picked from commit bb448f3dc2)
This commit is contained in:
Gusted 2024-08-07 17:04:03 +02:00 committed by forgejo-backport-action
parent 1c0043efd6
commit dccf180307
2 changed files with 5 additions and 1 deletions

View file

@ -179,6 +179,7 @@ func createDefaultPolicy() *bluemonday.Policy {
// repository descriptions.
func createRepoDescriptionPolicy() *bluemonday.Policy {
policy := bluemonday.NewPolicy()
policy.AllowStandardURLs()
// Allow italics and bold.
policy.AllowElements("i", "b", "em", "strong")

View file

@ -82,12 +82,15 @@ func TestDescriptionSanitizer(t *testing.T) {
`<span class="emoji" aria-label="thumbs up">THUMBS UP</span>`, `<span class="emoji" aria-label="thumbs up">THUMBS UP</span>`,
`<span style="color: red">Hello World</span>`, `<span>Hello World</span>`,
`<br>`, ``,
`<a href="https://example.com" target="_blank" rel="noopener noreferrer">https://example.com</a>`, `<a href="https://example.com" target="_blank" rel="noopener noreferrer">https://example.com</a>`,
`<a href="https://example.com" target="_blank" rel="noopener noreferrer">https://example.com</a>`, `<a href="https://example.com" target="_blank" rel="noopener noreferrer nofollow">https://example.com</a>`,
`<mark>Important!</mark>`, `Important!`,
`<details>Click me! <summary>Nothing to see here.</summary></details>`, `Click me! Nothing to see here.`,
`<input type="hidden">`, ``,
`<b>I</b> have a <i>strong</i> <strong>opinion</strong> about <em>this</em>.`, `<b>I</b> have a <i>strong</i> <strong>opinion</strong> about <em>this</em>.`,
`Provides alternative <code>wg(8)</code> tool`, `Provides alternative <code>wg(8)</code> tool`,
`<a href="javascript:alert('xss')">Click me</a>.`, `Click me.`,
`<a href="data:text/html,<script>alert('xss')</script>">Click me</a>.`, `Click me.`,
`<a href="vbscript:msgbox("xss")">Click me</a>.`, `Click me.`,
}
for i := 0; i < len(testCases); i += 2 {