From: Cornelia Huck <cohuck@redhat.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, freude@linux.ibm.com,
borntraeger@de.ibm.com, frankja@linux.ibm.com, david@redhat.com,
mjrosato@linux.ibm.com, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, pmorel@linux.ibm.com,
pasic@linux.ibm.com, alex.williamson@redhat.com,
kwankhede@nvidia.com
Subject: Re: [PATCH v4 3/7] s390: zcrypt: driver callback to indicate resource in use
Date: Tue, 18 Jun 2019 18:25:58 +0200 [thread overview]
Message-ID: <20190618182558.7d7e025a.cohuck@redhat.com> (raw)
In-Reply-To: <1560454780-20359-4-git-send-email-akrowiak@linux.ibm.com>
On Thu, 13 Jun 2019 15:39:36 -0400
Tony Krowiak <akrowiak@linux.ibm.com> wrote:
> Introduces a new driver callback to prevent a root user from unbinding
> an AP queue from its device driver if the queue is in use. This prevents
> a root user from inadvertently taking a queue away from a guest and
> giving it to the host, or vice versa. The callback will be invoked
> whenever a change to the AP bus's apmask or aqmask sysfs interfaces may
> result in one or more AP queues being removed from its driver. If the
> callback responds in the affirmative for any driver queried, the change
> to the apmask or aqmask will be rejected with a device in use error.
>
> For this patch, only non-default drivers will be queried. Currently,
> there is only one non-default driver, the vfio_ap device driver. The
> vfio_ap device driver manages AP queues passed through to one or more
> guests and we don't want to unexpectedly take AP resources away from
> guests which are most likely independently administered.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> drivers/s390/crypto/ap_bus.c | 138 +++++++++++++++++++++++++++++++++++++++++--
> drivers/s390/crypto/ap_bus.h | 3 +
> 2 files changed, 135 insertions(+), 6 deletions(-)
Hm... I recall objecting to this patch before, fearing that it makes it
possible for a bad actor to hog resources that can't be removed by
root, even forcefully. (I have not had time to look at the intervening
versions, so I might be missing something.)
Is there a way for root to forcefully override this?
next prev parent reply other threads:[~2019-06-18 16:26 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-13 19:39 [PATCH v4 0/7] s390: vfio-ap: dynamic configuration support Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 1/7] s390: vfio-ap: Refactor vfio_ap driver probe and remove callbacks Tony Krowiak
2019-06-17 8:27 ` Harald Freudenberger
2019-06-17 14:24 ` Tony Krowiak
2019-06-18 16:14 ` Cornelia Huck
2019-06-19 12:31 ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 2/7] s390: vfio-ap: wait for queue empty on queue reset Tony Krowiak
2019-06-17 8:47 ` Harald Freudenberger
2019-06-17 14:29 ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 3/7] s390: zcrypt: driver callback to indicate resource in use Tony Krowiak
2019-06-17 9:28 ` Harald Freudenberger
2019-06-17 14:37 ` Tony Krowiak
2019-06-18 16:25 ` Cornelia Huck [this message]
2019-06-19 13:04 ` Tony Krowiak
2019-06-26 21:13 ` Tony Krowiak
2019-06-27 7:25 ` Cornelia Huck
2019-06-27 12:59 ` Tony Krowiak
2019-07-01 19:26 ` Cornelia Huck
2019-07-08 14:27 ` Tony Krowiak
2019-07-09 10:49 ` Cornelia Huck
2019-07-09 21:11 ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 4/7] s390: vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 5/7] s390: vfio-ap: allow assignment of unavailable AP resources to mdev device Tony Krowiak
2019-06-17 10:05 ` Harald Freudenberger
2019-06-17 15:07 ` Tony Krowiak
2019-06-18 6:49 ` Harald Freudenberger
2019-06-19 13:39 ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 6/7] s390: vfio-ap: allow hot plug/unplug of AP resources using " Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 7/7] s390: vfio-ap: update documentation Tony Krowiak
2019-06-17 11:42 ` Harald Freudenberger
2019-06-17 15:21 ` Tony Krowiak
2019-07-09 15:30 ` [PATCH v4 0/7] s390: vfio-ap: dynamic configuration support Halil Pasic
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