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From: "Mickaël Salaün" <mic@digikod.net>
To: Tristan Schmelcher <tschmelcher@google.com>
Cc: linux-kernel@vger.kernel.org, Jeff Dike <jdike@addtoit.com>,
	Richard Weinberger <richard@nod.at>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	user-mode-linux-devel
	<user-mode-linux-devel@lists.sourceforge.net>,
	user-mode-linux-user@lists.sourceforge.net
Subject: Re: [PATCH v2 1/2] um: Set secure access mode for temporary file
Date: Sun, 6 Dec 2015 12:32:58 +0100	[thread overview]
Message-ID: <56641CEA.5080202@digikod.net> (raw)
In-Reply-To: <CADNZ+wSJtq9Ymx-2YcYe5XwwXTmMdbtsuBz6JHotnnwH3G7GKg@mail.gmail.com>

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On 04/12/2015 18:13, Tristan Schmelcher wrote:
> File permissions are checked at time of open, so I think this fchmod
> call has never had any effect.

Indeed, mmap doesn't require the file to be executable, only readable and writable. The fchmod seems to be a guarantee for this permissions but I don't see why a file newly created could not be writable.

> 
> If there is a concern that the mkstemp implementation may be insecure,
> why not set and restore the umask?
> 

I will add this safeguard.

 Mickaël


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  reply	other threads:[~2015-12-06 12:11 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-29 14:03 [PATCH v2 0/2] um: Protect memory mapped file Mickaël Salaün
2015-11-29 14:03 ` Mickaël Salaün
2015-11-29 14:03 ` [PATCH v2 1/2] um: Set secure access mode for temporary file Mickaël Salaün
2015-11-29 14:03   ` Mickaël Salaün
2015-12-04 17:13   ` Tristan Schmelcher
2015-12-06 11:32     ` Mickaël Salaün [this message]
2015-12-06 11:57       ` Mickaël Salaün
2015-12-06 14:43       ` Mickaël Salaün
2015-12-08 20:37         ` Tristan Schmelcher
2015-12-08 20:37           ` Tristan Schmelcher
2015-12-08 21:45           ` Richard Weinberger
2015-12-08 21:45             ` [uml-devel] " Richard Weinberger
2015-12-09 23:58             ` Mickaël Salaün
2015-11-29 14:03 ` [PATCH v2 2/2] um: Use race-free temporary file creation Mickaël Salaün
2015-11-29 14:03   ` Mickaël Salaün
2015-12-04 17:26   ` Tristan Schmelcher

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