Hide sensitive tokens from install/test/post.

Hide these tokens to avoid malicious subprocesses e.g. sending them
over the network. Also, support using these tokens with environment
filtering and clear `HOMEBREW_PATH` from subprocesses to stop them
sniffing it. Finally, use `HOMEBREW_PATH` to detect Homebrew’s user’s
PATH for e.g. `brew doctor` etc.

1 files changed, 7 insertions, 0 deletions

diff --git a/Library/Homebrew/extend/ENV.rb b/Library/Homebrew/extend/ENV.rb
index 729598e28..283e90b69 100644
--- a/Library/Homebrew/extend/ENV.rb
+++ b/Library/Homebrew/extend/ENV.rb
@@ -26,6 +26,13 @@ module EnvActivation
   ensure
     replace(old_env)
   end
+
+  def clear_sensitive_environment!
+    ENV.keys.each do |key|
+      next unless /(cookie|key|token)/i =~ key
+      ENV.delete key
+    end
+  end
 end
 
 ENV.extend(EnvActivation)