linux-kernel - Re: [v2 2/2] vfio iommu type1: fix the testing of capability for remote task

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Message-ID: <alpine.LRH.2.20.1701130922090.4964@namei.org>
Date:   Fri, 13 Jan 2017 09:22:18 +1100 (AEDT)
From:   James Morris <jmorris@...ei.org>
To:     Jike Song <jike.song@...el.com>
cc:     alex.williamson@...hat.com, serge@...lyn.com, kwankhede@...dia.com,
        kraxel@...hat.com, linux-security-module@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [v2 2/2] vfio iommu type1: fix the testing of capability for
 remote task

On Thu, 12 Jan 2017, Jike Song wrote:

> Before the mdev enhancement type1 iommu used capable() to test the
> capability of current task; in the course of mdev development a
> new requirement, testing for another task other than current, was
> raised.  ns_capable() was used for this purpose, however it still
> tests current, the only difference is, in a specified namespace.
> 
> Fix it by using has_capability() instead, which tests the cap for
> specified task in init_user_ns, the same namespace as capable().
> 
> Cc: Alex Williamson <alex.williamson@...hat.com>
> Cc: Kirti Wankhede <kwankhede@...dia.com>
> Cc: Gerd Hoffmann <kraxel@...hat.com>
> Signed-off-by: Jike Song <jike.song@...el.com>


Reviewed-by: James Morris <james.l.morris@...cle.com>

> ---
>  drivers/vfio/vfio_iommu_type1.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 9266271..77373e5 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -495,8 +495,7 @@ static int vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr,
>  				  unsigned long *pfn_base, bool do_accounting)
>  {
>  	unsigned long limit;
> -	bool lock_cap = ns_capable(task_active_pid_ns(dma->task)->user_ns,
> -				   CAP_IPC_LOCK);
> +	bool lock_cap = has_capability(dma->task, CAP_IPC_LOCK);
>  	struct mm_struct *mm;
>  	int ret;
>  	bool rsvd;
> 

-- 
James Morris
<jmorris@...ei.org>