From d76c30935460ded953792dfe49f72b8c5158e899 Mon Sep 17 00:00:00 2001
From: Daniel Pittman <daniel@puppetlabs.com>
Date: Wed, 28 Sep 2011 23:35:19 -0700
Subject: [PATCH] (#9792) Predictable temporary filename in ralsh.

When ralsh is used in edit mode the temporary filename is in a shared
directory, and is absolutely predictable.  Worse, it won't be touched until
well after the startup of the command.

It can be tricked into writing through a symlink to edit any file on the
system, or to create through it, but worse - the file is reopened with the
same name later, so it can have the target replaced between edit and
operate...

The only possible mitigation comes from the system editor and the behaviour it
has around editing through symbolic links, which is very weak.

This improves this to prefer the current working directory for the temporary
file, and to be somewhat less predictable and more safe in conjuring it into
being.

Fixes CVE-2011-3871

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>
---
 lib/puppet/application/resource.rb | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/lib/puppet/application/resource.rb b/lib/puppet/application/resource.rb
index 76d0fada81a..b1a3f8887ed 100644
--- a/lib/puppet/application/resource.rb
+++ b/lib/puppet/application/resource.rb
@@ -190,18 +190,25 @@ def main
     end.map(&format).join("\n")
 
     if options[:edit]
-      file = "/tmp/x2puppet-#{Process.pid}.pp"
+      require 'tempfile'
+      # Prefer the current directory, which is more likely to be secure
+      # and, in the case of interactive use, accessible to the user.
+      tmpfile = Tempfile.new('x2puppet', Dir.pwd)
       begin
-        File.open(file, "w") do |f|
-          f.puts text
-        end
-        ENV["EDITOR"] ||= "vi"
-        system(ENV["EDITOR"], file)
-        system("puppet -v #{file}")
+        # sync write, so nothing buffers before we invoke the editor.
+        tmpfile.sync = true
+        tmpfile.puts text
+
+        # edit the content
+        system(ENV["EDITOR"] || 'vi', tmpfile.path)
+
+        # ...and, now, pass that file to puppet to apply.  Because
+        # many editors rename or replace the original file we need to
+        # feed the pathname, not the file content itself, to puppet.
+        system('puppet -v ' + tmpfile.path)
       ensure
-        #if FileTest.exists? file
-        #    File.unlink(file)
-        #end
+        # The temporary file will be safely removed.
+        tmpfile.close(true)
       end
     else
       puts text