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

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Date:	Sun, 6 Dec 2015 15:43:47 +0100
From:	Mickaël Salaün <mic@...ikod.net>
To:	Tristan Schmelcher <tschmelcher@...gle.com>
Cc:	linux-kernel@...r.kernel.org, Jeff Dike <jdike@...toit.com>,
	Richard Weinberger <richard@....at>,
	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

On 06/12/2015 12:32, Mickaël Salaün wrote:
> On 04/12/2015 18:13, Tristan Schmelcher wrote:
>> If there is a concern that the mkstemp implementation may be insecure,
>> why not set and restore the umask?
>>
> 
> I will add this safeguard.

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. I prefer to stick to fchmod and handle the race-condition with O_TMPFILE unsell someone is sure that this will not create bugs :)

 Mickaël


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