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authorFenghua Yu2022-10-14 15:25:41 -0700
committerVinod Koul2022-10-19 19:02:10 +0530
commit0ec8ce07394442d722806fe61b901a5b2b17249d (patch)
tree2541d70f3a4e7fe628065ef9d01dada7aa115ec5
parent5a637f83d96fc9f27e93385924e7253a5f5187bc (diff)
dmaengine: idxd: Do not enable user type Work Queue without Shared Virtual Addressing
When the idxd_user_drv driver is bound to a Work Queue (WQ) device without IOMMU or with IOMMU Passthrough without Shared Virtual Addressing (SVA), the application gains direct access to physical memory via the device by programming physical address to a submitted descriptor. This allows direct userspace read and write access to arbitrary physical memory. This is inconsistent with the security goals of a good kernel API. Unlike vfio_pci driver, the IDXD char device driver does not provide any ways to pin user pages and translate the address from user VA to IOVA or PA without IOMMU SVA. Therefore the application has no way to instruct the device to perform DMA function. This makes the char device not usable for normal application usage. Since user type WQ without SVA cannot be used for normal application usage and presents the security issue, bind idxd_user_drv driver and enable user type WQ only when SVA is enabled (i.e. user PASID is enabled). Fixes: 448c3de8ac83 ("dmaengine: idxd: create user driver for wq 'device'") Cc: stable@vger.kernel.org Suggested-by: Arjan Van De Ven <arjan.van.de.ven@intel.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com> Link: https://lore.kernel.org/r/20221014222541.3912195-1-fenghua.yu@intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
-rw-r--r--drivers/dma/idxd/cdev.c18
-rw-r--r--include/uapi/linux/idxd.h1
2 files changed, 19 insertions, 0 deletions
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index c2808fd081d6..a9b96b18772f 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -312,6 +312,24 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
if (idxd->state != IDXD_DEV_ENABLED)
return -ENXIO;
+ /*
+ * User type WQ is enabled only when SVA is enabled for two reasons:
+ * - If no IOMMU or IOMMU Passthrough without SVA, userspace
+ * can directly access physical address through the WQ.
+ * - The IDXD cdev driver does not provide any ways to pin
+ * user pages and translate the address from user VA to IOVA or
+ * PA without IOMMU SVA. Therefore the application has no way
+ * to instruct the device to perform DMA function. This makes
+ * the cdev not usable for normal application usage.
+ */
+ if (!device_user_pasid_enabled(idxd)) {
+ idxd->cmd_status = IDXD_SCMD_WQ_USER_NO_IOMMU;
+ dev_dbg(&idxd->pdev->dev,
+ "User type WQ cannot be enabled without SVA.\n");
+
+ return -EOPNOTSUPP;
+ }
+
mutex_lock(&wq->wq_lock);
wq->type = IDXD_WQT_USER;
rc = drv_enable_wq(wq);
diff --git a/include/uapi/linux/idxd.h b/include/uapi/linux/idxd.h
index 095299c75828..2b9e7feba3f3 100644
--- a/include/uapi/linux/idxd.h
+++ b/include/uapi/linux/idxd.h
@@ -29,6 +29,7 @@ enum idxd_scmd_stat {
IDXD_SCMD_WQ_NO_SIZE = 0x800e0000,
IDXD_SCMD_WQ_NO_PRIV = 0x800f0000,
IDXD_SCMD_WQ_IRQ_ERR = 0x80100000,
+ IDXD_SCMD_WQ_USER_NO_IOMMU = 0x80110000,
};
#define IDXD_SCMD_SOFTERR_MASK 0x80000000