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Commit d8099663 authored by Roger Pau Monne's avatar Roger Pau Monne Committed by Greg Kroah-Hartman
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xen/privcmd: allow fetching resource sizes 



commit ef3a575baf53571dc405ee4028e26f50856898e7 upstream.

Allow issuing an IOCTL_PRIVCMD_MMAP_RESOURCE ioctl with num = 0 and
addr = 0 in order to fetch the size of a specific resource.

Add a shortcut to the default map resource path, since fetching the
size requires no address to be passed in, and thus no VMA to setup.

This is missing from the initial implementation, and causes issues
when mapping resources that don't have fixed or known sizes.

Signed-off-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Tested-by: default avatarAndrew Cooper <andrew.cooper3@citrix.com>
Cc: stable@vger.kernel.org # >= 4.18
Link: https://lore.kernel.org/r/20210112115358.23346-1-roger.pau@citrix.com


Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8445d956

drivers/xen/privcmd.c

+19 −6
Original line number Diff line number Diff line
@@ -743,14 +743,15 @@ static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr, 
	return 0;

}



static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)

static long privcmd_ioctl_mmap_resource(struct file *file,

				struct privcmd_mmap_resource __user *udata)

{

	struct privcmd_data *data = file->private_data;

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	struct privcmd_mmap_resource kdata;

	xen_pfn_t *pfns = NULL;

	struct xen_mem_acquire_resource xdata;

	struct xen_mem_acquire_resource xdata = { };

	int rc;



	if (copy_from_user(&kdata, udata, sizeof(kdata)))
@@ -760,6 +761,22 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata) 
	if (data->domid != DOMID_INVALID && data->domid != kdata.dom)

		return -EPERM;



	/* Both fields must be set or unset */

	if (!!kdata.addr != !!kdata.num)

		return -EINVAL;



	xdata.domid = kdata.dom;

	xdata.type = kdata.type;

	xdata.id = kdata.id;



	if (!kdata.addr && !kdata.num) {

		/* Query the size of the resource. */

		rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);

		if (rc)

			return rc;

		return __put_user(xdata.nr_frames, &udata->num);

	}



	down_write(&mm->mmap_sem);



	vma = find_vma(mm, kdata.addr);
@@ -793,10 +810,6 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata) 
	} else

		vma->vm_private_data = PRIV_VMA_LOCKED;



	memset(&xdata, 0, sizeof(xdata));

	xdata.domid = kdata.dom;

	xdata.type = kdata.type;

	xdata.id = kdata.id;

	xdata.frame = kdata.idx;

	xdata.nr_frames = kdata.num;

	set_xen_guest_handle(xdata.frame_list, pfns);