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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>
This commit is contained in:
Matt McCutchen 2009-02-07 19:00:09 -05:00 committed by Junio C Hamano
parent 6e46cc0d92
commit 7e1100e9e9
2 changed files with 27 additions and 3 deletions

@ -214,6 +214,11 @@ not include variables usually directly set during build):
Rename detection options for git-diff and git-diff-tree. By default
('-M'); set it to ('-C') or ('-C', '-C') to also detect copies, or
set it to () if you don't want to have renames detection.
* $prevent_xss
If true, some gitweb features are disabled to prevent content in
repositories from launching cross-site scripting (XSS) attacks. Set this
to true if you don't trust the content of your repositories. The default
is false.
Projects list file format
@ -260,7 +265,9 @@ You can use the following files in repository:
A .html file (HTML fragment) which is included on the gitweb project
summary page inside <div> block element. You can use it for longer
description of a project, to provide links (for example to project's
homepage), etc.
homepage), etc. This is recognized only if XSS prevention is off
($prevent_xss is false); a way to include a readme safely when XSS
prevention is on may be worked out in the future.
* description (or gitweb.description)
Short (shortened by default to 25 characters in the projects list page)
single line description of a project (of a repository). Plain text file;

@ -132,6 +132,10 @@ our $fallback_encoding = 'latin1';
# - 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>;