Merge pull request 'disallow javascript: URI in the repository description' (#4896) from earl-warren/forgejo:wip-xss-repo-description into forgejo

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4896
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>

modules/markup/sanitizer.go

@@ -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")

modules/markup/sanitizer_test.go

@@ -84,12 +84,15 @@ 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 {