linux-kernel - Re: [RFC PATCH] Show data flow for file copyup in unions

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Message-ID: <20335.1268779891@jrobl>
Date:	Wed, 17 Mar 2010 07:51:31 +0900
From:	"J. R. Okajima" <hooanon05@...oo.co.jp>
To:	Valerie Aurora <vaurora@...hat.com>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	Miklos Szeredi <miklos@...redi.hu>,
	Dmitry Monakhov <dmonakhov@...nvz.org>,
	Jeff Layton <jlayton@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] Show data flow for file copyup in unions


Valerie Aurora:
> 1. Don't copyup if the operation would fail (e.g., open(O_WRONLY) on a
> file with mode 444).  It's inefficient and a possible security hole to
> copy up a file if no write (or maybe even read) can occur anyway.

Just a question.
How about this case?
When the file is writable (0644 or something) but its parent directory
is readonly (0555), do you think the file should be copied-up?


J. R. Okajima
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