linux-kernel - Re: [PATCH] vhost-vdpa: honor CAP_IPC

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Message-ID: <4f3dcc1e-b95d-f17c-b371-52119d693d10@redhat.com>
Date:   Tue, 2 Mar 2021 18:52:27 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vhost-vdpa: honor CAP_IPC_LOCK


On 2021/3/2 5:51 下午, Michael S. Tsirkin wrote:
> On Tue, Mar 02, 2021 at 04:14:18AM -0500, Jason Wang wrote:
>> When CAP_IPC_LOCK is set we should not check locked memory against
>> rlimit as what has been implemented in mlock().
>>
>> Signed-off-by: Jason Wang <jasowang@...hat.com>
> Indeed and it's not just mlock.
>
> Documentation/admin-guide/perf-security.rst:
>
> RLIMIT_MEMLOCK and perf_event_mlock_kb resource constraints are ignored
> for processes with the CAP_IPC_LOCK capability.
>
> and let's add a Fixes: tag?


Sure, V2 is posted.

Thanks


>
>> ---
>>   drivers/vhost/vdpa.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>> index ef688c8c0e0e..e93572e2e344 100644
>> --- a/drivers/vhost/vdpa.c
>> +++ b/drivers/vhost/vdpa.c
>> @@ -638,7 +638,8 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
>>   	mmap_read_lock(dev->mm);
>>   
>>   	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>> -	if (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit) {
>> +	if (!capable(CAP_IPC_LOCK) &&
>> +	    (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit)) {
>>   		ret = -ENOMEM;
>>   		goto unlock;
>>   	}
>> -- 
>> 2.18.1