The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

0ec8ce073944 ("dmaengine: idxd: Do not enable user type Work Queue without Shared Virtual Addressing") 403a2e236538 ("dmaengine: idxd: change MSIX allocation based on per wq activation") 23a50c803565 ("dmaengine: idxd: fix descriptor flushing locking") ec0d64231615 ("dmaengine: idxd: embed irq_entry in idxd_wq struct") 56fc39f5a367 ("dmaengine: idxd: handle interrupt handle revoked event") f6d442f7088c ("dmaengine: idxd: handle invalid interrupt handle descriptors") bd5970a0d01f ("dmaengine: idxd: create locked version of idxd_quiesce() call") 46c6df1c958e ("dmaengine: idxd: add helper for per interrupt handle drain") eb0cf33a91b4 ("dmaengine: idxd: move interrupt handle assignment") 8b67426e0558 ("dmaengine: idxd: int handle management refactoring") 5d78abb6fbc9 ("dmaengine: idxd: rework descriptor free path on failure") a3e340c1574b ("dmaengine: idxd: fix resource leak on dmaengine driver disable") e530a9f3db41 ("dmaengine: idxd: reconfig device after device reset command") 88d97ea82cbe ("dmaengine: idxd: add halt interrupt support") 85f604af9c83 ("dmaengine: idxd: move out percpu_ref_exit() to ensure it's outside submission")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0ec8ce07394442d722806fe61b901a5b2b17249d Mon Sep 17 00:00:00 2001 From: Fenghua Yu fenghua.yu@intel.com Date: Fri, 14 Oct 2022 15:25:41 -0700 Subject: [PATCH] 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

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