gitweb: add $prevent_xss option to prevent XSS by repository content
Add a gitweb configuration variable $prevent_xss that disables features
to prevent content in repositories from launching cross-site scripting
(XSS) attacks in the gitweb domain. Currently, this option makes gitweb
ignore README.html (a better solution may be worked out in the future)
and serve a blob_plain file of an untrusted type with
"Content-Disposition: attachment", which tells the browser not to show
the file at its original URL.
The XSS prevention is currently off by default.
Signed-off-by: Matt McCutchen <matt@mattmccutchen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 99f71b4..bdaa4e9 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -132,6 +132,10 @@
# - 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 $prevent_xss = 0;
+
# information about snapshot formats that gitweb is capable of serving
our %known_snapshot_formats = (
# name => {
@@ -4494,7 +4498,9 @@
print "</table>\n";
- if (-s "$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 @@
$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>;
