linux-kernel - Re: [RFC][PATCH] um: Remove proc command from mconsole

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Message-ID: <20170521213029.GB390@ZenIV.linux.org.uk>
Date:   Sun, 21 May 2017 22:30:29 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Richard Weinberger <richard@....at>
Cc:     user-mode-linux-devel@...ts.sourceforge.net,
        user-mode-linux-user@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, hch@....de
Subject: Re: [RFC][PATCH] um: Remove proc command from mconsole

On Sun, May 21, 2017 at 11:19:03PM +0200, Richard Weinberger wrote:
> This feature is another abuser of set_fs().
> Reading proc files from the host side is a debugging feature
> with no security checks at all. The path is not sanitized, therefore
> any file could be read.

ITYM "any file on procfs"

> Let's get rid of it.

Wait a sec - guest is not protected against anyone with mconsole access
anyway.

> Unless I miss something is feature is not ABI since it was addeded for
> debugging UML only. It is broken wrt. security and abuses set_fs().
> I think we can just remove it.

IDGI.  set_fs() abuses are trivial - just switch to kernel_read() and
be done with that...