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Subject[PATCH] virt: vbox: Sanity-check parameter types for hgcm-calls coming from userspace
Date
Userspace can make host function calls, called hgcm-calls through the
/dev/vboxguest device.

In this case we should not accept all hgcm-function-parameter-types, some
are only valid for in kernel calls.

This commit adds proper hgcm-function-parameter-type validation to the
ioctl for doing a hgcm-call from userspace.

Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/virt/vboxguest/vboxguest_core.c | 31 +++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/drivers/virt/vboxguest/vboxguest_core.c b/drivers/virt/vboxguest/vboxguest_core.c
index 8ca333f21292..2307b0329aec 100644
--- a/drivers/virt/vboxguest/vboxguest_core.c
+++ b/drivers/virt/vboxguest/vboxguest_core.c
@@ -1298,6 +1298,20 @@ static int vbg_ioctl_hgcm_disconnect(struct vbg_dev *gdev,
return ret;
}

+static bool vbg_param_valid(enum vmmdev_hgcm_function_parameter_type type)
+{
+ switch (type) {
+ case VMMDEV_HGCM_PARM_TYPE_32BIT:
+ case VMMDEV_HGCM_PARM_TYPE_64BIT:
+ case VMMDEV_HGCM_PARM_TYPE_LINADDR:
+ case VMMDEV_HGCM_PARM_TYPE_LINADDR_IN:
+ case VMMDEV_HGCM_PARM_TYPE_LINADDR_OUT:
+ return true;
+ default:
+ return false;
+ }
+}
+
static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev,
struct vbg_session *session, bool f32bit,
struct vbg_ioctl_hgcm_call *call)
@@ -1333,6 +1347,23 @@ static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev,
}
call->hdr.size_out = actual_size;

+ /* Validate parameter types */
+ if (f32bit) {
+ struct vmmdev_hgcm_function_parameter32 *parm =
+ VBG_IOCTL_HGCM_CALL_PARMS32(call);
+
+ for (i = 0; i < call->parm_count; i++)
+ if (!vbg_param_valid(parm[i].type))
+ return -EINVAL;
+ } else {
+ struct vmmdev_hgcm_function_parameter *parm =
+ VBG_IOCTL_HGCM_CALL_PARMS(call);
+
+ for (i = 0; i < call->parm_count; i++)
+ if (!vbg_param_valid(parm[i].type))
+ return -EINVAL;
+ }
+
/*
* Validate the client id.
*/
--
2.21.0
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