linux-kernel - Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O

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Message-Id: <3557EF65-4327-4DAE-999A-B0EE13C433F5@suse.de>
Date:	Sun, 25 Aug 2013 16:04:21 +0100
From:	Alexander Graf <agraf@...e.de>
To:	Yann Droneaud <ydroneaud@...eya.com>
Cc:	Gleb Natapov <gleb@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag


On 24.08.2013, at 21:14, Yann Droneaud wrote:

> KVM uses anon_inode_get() to allocate file descriptors as part
> of some of its ioctls. But those ioctls are lacking a flag argument
> allowing userspace to choose options for the newly opened file descriptor.
> 
> In such case it's advised to use O_CLOEXEC by default so that
> userspace is allowed to choose, without race, if the file descriptor
> is going to be inherited across exec().
> 
> This patch set O_CLOEXEC flag on all file descriptors created
> with anon_inode_getfd() to not leak file descriptors across exec().
> 
> Signed-off-by: Yann Droneaud <ydroneaud@...eya.com>
> Link: http://lkml.kernel.org/r/cover.1377372576.git.ydroneaud@opteya.com

Reviewed-by: Alexander Graf <agraf@...e.de>

Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to.


Alex

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