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Userspace code using uio_pci_generic may enable bus-mastering by directly manipulating a PCI device's command register. If a userspace program enables bus-mastering but exits/crashes uncleanly, bus- mastering will still be enabled and stale DMA addresses may be programmed and live in the device. Disable bus-mastering unconditionally on last close of a UIO PCI fd to avoid this. If the device did not have bus-mastering enabled, pci_clear_master() is a no-op. Signed-off-by: Venkatesh Srinivas <venkateshs@google.com> Reviewed-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Catherine Sullivan <csully@google.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
142 lines
3.7 KiB
C
142 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
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*
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* Copyright (C) 2009 Red Hat, Inc.
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* Author: Michael S. Tsirkin <mst@redhat.com>
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*
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* Since the driver does not declare any device ids, you must allocate
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* id and bind the device to the driver yourself. For example:
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*
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* # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
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* # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
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* .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
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*
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* Driver won't bind to devices which do not support the Interrupt Disable Bit
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* in the command register. All devices compliant to PCI 2.3 (circa 2002) and
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* all compliant PCI Express devices should support this bit.
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*/
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/slab.h>
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#include <linux/uio_driver.h>
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#define DRIVER_VERSION "0.01.0"
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#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@redhat.com>"
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#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"
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struct uio_pci_generic_dev {
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struct uio_info info;
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struct pci_dev *pdev;
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};
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static inline struct uio_pci_generic_dev *
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to_uio_pci_generic_dev(struct uio_info *info)
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{
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return container_of(info, struct uio_pci_generic_dev, info);
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}
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static int release(struct uio_info *info, struct inode *inode)
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{
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struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
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/*
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* This driver is insecure when used with devices doing DMA, but some
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* people (mis)use it with such devices.
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* Let's at least make sure DMA isn't left enabled after the userspace
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* driver closes the fd.
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* Note that there's a non-zero chance doing this will wedge the device
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* at least until reset.
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*/
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pci_clear_master(gdev->pdev);
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return 0;
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}
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/* Interrupt handler. Read/modify/write the command register to disable
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* the interrupt. */
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static irqreturn_t irqhandler(int irq, struct uio_info *info)
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{
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struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
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if (!pci_check_and_mask_intx(gdev->pdev))
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return IRQ_NONE;
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/* UIO core will signal the user process. */
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return IRQ_HANDLED;
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}
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static int probe(struct pci_dev *pdev,
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const struct pci_device_id *id)
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{
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struct uio_pci_generic_dev *gdev;
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int err;
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err = pci_enable_device(pdev);
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if (err) {
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dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
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__func__, err);
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return err;
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}
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if (pdev->irq && !pci_intx_mask_supported(pdev)) {
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err = -ENODEV;
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goto err_verify;
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}
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gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
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if (!gdev) {
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err = -ENOMEM;
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goto err_alloc;
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}
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gdev->info.name = "uio_pci_generic";
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gdev->info.version = DRIVER_VERSION;
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gdev->info.release = release;
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gdev->pdev = pdev;
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if (pdev->irq) {
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gdev->info.irq = pdev->irq;
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gdev->info.irq_flags = IRQF_SHARED;
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gdev->info.handler = irqhandler;
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} else {
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dev_warn(&pdev->dev, "No IRQ assigned to device: "
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"no support for interrupts?\n");
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}
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err = uio_register_device(&pdev->dev, &gdev->info);
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if (err)
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goto err_register;
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pci_set_drvdata(pdev, gdev);
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return 0;
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err_register:
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kfree(gdev);
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err_alloc:
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err_verify:
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pci_disable_device(pdev);
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return err;
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}
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static void remove(struct pci_dev *pdev)
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{
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struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
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uio_unregister_device(&gdev->info);
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pci_disable_device(pdev);
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kfree(gdev);
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}
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static struct pci_driver uio_pci_driver = {
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.name = "uio_pci_generic",
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.id_table = NULL, /* only dynamic id's */
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.probe = probe,
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.remove = remove,
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};
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module_pci_driver(uio_pci_driver);
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MODULE_VERSION(DRIVER_VERSION);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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