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

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Date:   Fri, 23 Dec 2016 10:36:55 +0800
From:   Jike Song <jike.song@...el.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
CC:     serge@...lyn.com, alex.williamson@...hat.com,
        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 12/22/2016 08:20 PM, Kirti Wankhede wrote:
> 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.
> 

Thanks for the point, will change it in v2.  However, that will probably be
after patch 1/2 accepted, otherwise we get undefined symbols.

--
Thanks,
Jike

>>  	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;
>>