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

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Message-ID: <6beee519-15f3-1d4d-5ea7-20fa6ba56d1c@nvidia.com>
Date:   Thu, 22 Dec 2016 17:50:37 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Jike Song <jike.song@...el.com>, <serge@...lyn.com>,
        <alex.williamson@...hat.com>
CC:     <linux-security-module@...r.kernel.org>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <kraxel@...hat.com>
Subject: Re: [PATCH 2/2] vfio iommu type1: fix the testing of capability for
 remote task



On 12/21/2016 9:40 PM, 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>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index f3726ba..b54aedf 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -394,8 +394,7 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
>  				  long npage, unsigned long *pfn_base)
>  {
>  	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);


Hi Jike,

Alex's patch already changes this to capable(), you need to resolve.
https://lkml.org/lkml/2016/12/20/490

You need to do only below change, which looks fine to me.

>  	struct mm_struct *mm;
>  	long ret, i = 0, lock_acct = 0;
>  	bool rsvd;
> @@ -491,8 +490,7 @@ 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;
> 


Thanks,
Kirti