diff mbox series

[05/11] iommu: Add security context management for assigned devices

Message ID 20211115020552.2378167-6-baolu.lu@linux.intel.com (mailing list archive)
State Superseded
Delegated to: Bjorn Helgaas
Headers show
Series Fix BUG_ON in vfio_iommu_group_notifier() | expand

Commit Message

Baolu Lu Nov. 15, 2021, 2:05 a.m. UTC 
When an iommu group has DMA_OWNER_USER set for the first time, it is a
contract that the group could be assigned to userspace from now on. It
must be detached from the default iommu domain and all devices in this
group are blocked from doing DMA until it is attached to a user I/O
address space. Vice versa, the default domain should be re-attached to
the group after the last DMA_OWNER_USER is released.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/iommu.c | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

Comments

Christoph Hellwig Nov. 15, 2021, 1:22 p.m. UTC | #1 
On Mon, Nov 15, 2021 at 10:05:46AM +0800, Lu Baolu wrote:
> +			/*
> +			 * The UNMANAGED domain should be detached before all USER
> +			 * owners have been released.
> +			 */

Please avoid comments spilling over 80 characters.
Baolu Lu Nov. 16, 2021, 7:25 a.m. UTC | #2 
On 2021/11/15 21:22, Christoph Hellwig wrote:
> On Mon, Nov 15, 2021 at 10:05:46AM +0800, Lu Baolu wrote:
>> +			/*
>> +			 * The UNMANAGED domain should be detached before all USER
>> +			 * owners have been released.
>> +			 */
> 
> Please avoid comments spilling over 80 characters.

Sure! Thanks!

Best regards,
baolu
diff mbox series

Patch

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 39493b1b3edf..916a4d448150 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -293,7 +293,11 @@  int iommu_probe_device(struct device *dev)
 	mutex_lock(&group->mutex);
 	iommu_alloc_default_domain(group, dev);
 
-	if (group->default_domain) {
+	/*
+	 * If any device in the group has been initialized for user dma,
+	 * avoid attaching the default domain.
+	 */
+	if (group->default_domain && group->dma_owner != DMA_OWNER_USER) {
 		ret = __iommu_attach_device(group->default_domain, dev);
 		if (ret) {
 			mutex_unlock(&group->mutex);
@@ -2325,7 +2329,7 @@  static int __iommu_attach_group(struct iommu_domain *domain,
 {
 	int ret;
 
-	if (group->default_domain && group->domain != group->default_domain)
+	if (group->domain && group->domain != group->default_domain)
 		return -EBUSY;
 
 	ret = __iommu_group_for_each_dev(group, domain,
@@ -2362,7 +2366,11 @@  static void __iommu_detach_group(struct iommu_domain *domain,
 {
 	int ret;
 
-	if (!group->default_domain) {
+	/*
+	 * If any device in the group has been initialized for user dma,
+	 * avoid re-attaching the default domain.
+	 */
+	if (!group->default_domain || group->dma_owner == DMA_OWNER_USER) {
 		__iommu_group_for_each_dev(group, domain,
 					   iommu_group_do_detach_device);
 		group->domain = NULL;
@@ -3377,6 +3385,21 @@  static int __iommu_group_set_dma_owner(struct iommu_group *group,
 		refcount_set(&group->owner_cnt, 1);
 
 		if (owner == DMA_OWNER_USER) {
+			/*
+			 * The UNMANAGED domain shouldn't be attached before
+			 * claiming the USER ownership for the first time.
+			 */
+			if (group->domain) {
+				if (group->domain != group->default_domain) {
+					group->dma_owner = DMA_OWNER_NONE;
+					refcount_set(&group->owner_cnt, 0);
+
+					return -EBUSY;
+				}
+
+				__iommu_detach_group(group->domain, group);
+			}
+
 			get_file(user_file);
 			group->owner_user_file = user_file;
 		}
@@ -3397,6 +3420,13 @@  static void __iommu_group_release_dma_owner(struct iommu_group *group,
 		if (owner == DMA_OWNER_USER) {
 			fput(group->owner_user_file);
 			group->owner_user_file = NULL;
+
+			/*
+			 * The UNMANAGED domain should be detached before all USER
+			 * owners have been released.
+			 */
+			if (!WARN_ON(group->domain) && group->default_domain)
+				__iommu_attach_group(group->default_domain, group);
 		}
 	}
 }