linux-kernel - Re: [PATCH 0/2] kvm: use anon_inode_getfd() with O

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Date:	Mon, 26 Aug 2013 13:20:24 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	Yann Droneaud <ydroneaud@...eya.com>
Cc:	Alexander Graf <agraf@...e.de>,
	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 0/2] kvm: use anon_inode_getfd() with O_CLOEXEC flag

On Sat, Aug 24, 2013 at 10:14:06PM +0200, Yann Droneaud wrote:
> Hi,
> 
> Following a patchset asking to change calls to get_unused_flag() [1]
> to use O_CLOEXEC, Alex Williamson [2][3] decided to change VFIO
> to use the flag.
> 
> Since it's a related subsystem to KVM, using O_CLOEXEC for
> file descriptors created by KVM might be applicable too.
> 
> I'm suggesting to change calls to anon_inode_getfd() to use O_CLOEXEC
> as default flag.
> 
> This patchset should be reviewed to not break existing userspace program.
> 
> BTW, if it's not applicable, I would suggest that new ioctls be added to
> KVM subsystem, those ioctls would have a "flag" field added to their arguments.
> Such "flag" would let userspace choose the open flag to use.
> See for example other APIs using anon_inode_getfd() such as fanotify,
> inotify, signalfd and timerfd.
> 
> You might be interested to read:
> 
> - Secure File Descriptor Handling (Ulrich Drepper, 2008)
>   http://udrepper.livejournal.com/20407.html
> 
> - Excuse me son, but your code is leaking !!! (Dan Walsh, March 2012) 
>   http://danwalsh.livejournal.com/53603.html
> 
Applied, thanks.

> Regards.
> 
> [1] http://lkml.kernel.org/r/cover.1376327678.git.ydroneaud@opteya.com
> [2] http://lkml.kernel.org/r/1377186804.25163.17.camel@ul30vt.home
> [3] http://lkml.kernel.org/r/20130822171744.1297.13711.stgit@bling.home
> 
> Yann Droneaud (2):
>   kvm: use anon_inode_getfd() with O_CLOEXEC flag
>   ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
> 
>  arch/powerpc/kvm/book3s_64_mmu_hv.c | 2 +-
>  arch/powerpc/kvm/book3s_64_vio.c    | 2 +-
>  arch/powerpc/kvm/book3s_hv.c        | 2 +-
>  virt/kvm/kvm_main.c                 | 6 +++---
>  4 files changed, 6 insertions(+), 6 deletions(-)
> 
> -- 
> 1.8.3.1

--
			Gleb.
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