linux-kernel - Re: [PATCH v2 1/2] um: Set secure access mode for temporary file

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Date:	Tue, 8 Dec 2015 22:45:53 +0100
From:	Richard Weinberger <richard@....at>
To:	Tristan Schmelcher <tschmelcher@...gle.com>,
	Mickaël Salaün <mic@...ikod.net>
Cc:	linux-kernel@...r.kernel.org, Jeff Dike <jdike@...toit.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	user-mode-linux-devel <user-mode-linux-devel@...ts.sourceforge.net>,
	user-mode-linux-user@...ts.sourceforge.net
Subject: Re: [PATCH v2 1/2] um: Set secure access mode for temporary file

Am 08.12.2015 um 21:37 schrieb Tristan Schmelcher:
> On 6 December 2015 at 09:43, Mickaël Salaün <mic@...ikod.net> wrote:
>> Well, I'm concerned to use umask because it is not thread-safe and drivers may use create_mem_file() in a multi-theaded context.
> 
> You are right. We should perhaps set the umask to 0700 permanently
> during process start. But I am not sure if this will interfere with
> other UML code.

It *should* not hurt. Let's see what explodes. :)

>> I prefer to stick to fchmod and handle the race-condition with O_TMPFILE unsell someone is sure that this will not create bugs :)
> 
> The fchmod call is basically useless and should probably be removed.

I agree.

Thanks,
//richard
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