gitweb: add $prevent_xss option to prevent XSS by repository content

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 99f71b47c2a6b53bb52ce29e96361e7c2acbe19d..bdaa4e9463460a149a5c7f13881e5373257bc4e5 100755 (executable)
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -132,6 +132,10 @@ BEGIN
 # - one might want to include '-B' option, e.g. '-B', '-M'
 our @diff_opts = ('-M'); # taken from git_commit
 
+# Disables features that would allow repository owners to inject script into
+# the gitweb domain.
+our $prevent_xss = 0;
+
 # information about snapshot formats that gitweb is capable of serving
 our %known_snapshot_formats = (
        # name => {
@@ -4494,7 +4498,9 @@ sub git_summary {
 
        print "</table>\n";
 
-       if (-s "$projectroot/$project/README.html") {
+       # If XSS prevention is on, we don't include README.html.
+       # TODO: Allow a readme in some safe format.
+       if (!$prevent_xss && -s "$projectroot/$project/README.html") {
                print "<div class=\"title\">readme</div>\n" .
                      "<div class=\"readme\">\n";
                insert_file("$projectroot/$project/README.html");
@@ -4739,10 +4745,21 @@ sub git_blob_plain {
                $save_as .= '.txt';
        }
 
+       # With XSS prevention on, blobs of all types except a few known safe
+       # ones are served with "Content-Disposition: attachment" to make sure
+       # they don't run in our security domain.  For certain image types,
+       # blob view writes an <img> tag referring to blob_plain view, and we
+       # want to be sure not to break that by serving the image as an
+       # attachment (though Firefox 3 doesn't seem to care).
+       my $sandbox = $prevent_xss &&
+               $type !~ m!^(?:text/plain|image/(?:gif|png|jpeg))$!;
+
        print $cgi->header(
                -type => $type,
                -expires => $expires,
-               -content_disposition => 'inline; filename="' . $save_as . '"');
+               -content_disposition =>
+                       ($sandbox ? 'attachment' : 'inline')
+                       . '; filename="' . $save_as . '"');
        undef $/;
        binmode STDOUT, ':raw';
        print <$fd>;