Helps reviewing and understanding these checks.
v2: Remove misplaced newlines.
Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
Reviewed-by: David Herrmann <dh.herrmann at gmail.com>
---
drivers/gpu/drm/drm_drv.c | 113 ++++++++++++++++++++++++++++++---------------
1 file changed, 75 insertions(+), 38 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index ec651be..05e3053 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -286,6 +286,44 @@ static int drm_version(struct drm_device *dev, void *data,
}
/**
+ * drm_ioctl_permit - Check ioctl permissions against caller
+ *
+ * @flags: ioctl permission flags.
+ * @file_priv: Pointer to struct drm_file identifying the caller.
+ *
+ * Checks whether the caller is allowed to run an ioctl with the
+ * indicated permissions. If so, returns zero. Otherwise returns an
+ * error code suitable for ioctl return.
+ */
+static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
+{
+ /* ROOT_ONLY is only for CAP_SYS_ADMIN */
+ if (unlikely((flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN)))
+ return -EACCES;
+
+ /* AUTH is only for authenticated or render client */
+ if (unlikely((flags & DRM_AUTH) && !drm_is_render_client(file_priv) &&
+ !file_priv->authenticated))
+ return -EACCES;
+
+ /* MASTER is only for master */
+ if (unlikely((flags & DRM_MASTER) && !file_priv->is_master))
+ return -EACCES;
+
+ /* Control clients must be explicitly allowed */
+ if (unlikely(!(flags & DRM_CONTROL_ALLOW) &&
+ file_priv->minor->type == DRM_MINOR_CONTROL))
+ return -EACCES;
+
+ /* Render clients must be explicitly allowed */
+ if (unlikely(!(flags & DRM_RENDER_ALLOW) &&
+ drm_is_render_client(file_priv)))
+ return -EACCES;
+
+ return 0;
+}
+
+/**
* Called whenever a process performs an ioctl on /dev/drm.
*
* \param inode device inode.
@@ -350,52 +388,51 @@ long drm_ioctl(struct file *filp,
/* Do not trust userspace, use our own definition */
func = ioctl->func;
- if (!func) {
+ if (unlikely(!func)) {
DRM_DEBUG("no function\n");
retcode = -EINVAL;
- } else if (((ioctl->flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN))
||
- ((ioctl->flags & DRM_AUTH) &&
!drm_is_render_client(file_priv) && !file_priv->authenticated) ||
- ((ioctl->flags & DRM_MASTER) && !file_priv->is_master) ||
- (!(ioctl->flags & DRM_CONTROL_ALLOW) &&
(file_priv->minor->type == DRM_MINOR_CONTROL)) ||
- (!(ioctl->flags & DRM_RENDER_ALLOW) &&
drm_is_render_client(file_priv))) {
- retcode = -EACCES;
- } else {
- if (cmd & (IOC_IN | IOC_OUT)) {
- if (asize <= sizeof(stack_kdata)) {
- kdata = stack_kdata;
- } else {
- kdata = kmalloc(asize, GFP_KERNEL);
- if (!kdata) {
- retcode = -ENOMEM;
- goto err_i1;
- }
- }
- if (asize > usize)
- memset(kdata + usize, 0, asize - usize);
- }
+ goto err_i1;
+ }
- if (cmd & IOC_IN) {
- if (copy_from_user(kdata, (void __user *)arg,
- usize) != 0) {
- retcode = -EFAULT;
+ retcode = drm_ioctl_permit(ioctl->flags, file_priv);
+ if (unlikely(retcode))
+ goto err_i1;
+
+ if (cmd & (IOC_IN | IOC_OUT)) {
+ if (asize <= sizeof(stack_kdata)) {
+ kdata = stack_kdata;
+ } else {
+ kdata = kmalloc(asize, GFP_KERNEL);
+ if (!kdata) {
+ retcode = -ENOMEM;
goto err_i1;
}
- } else
- memset(kdata, 0, usize);
-
- if (ioctl->flags & DRM_UNLOCKED)
- retcode = func(dev, kdata, file_priv);
- else {
- mutex_lock(&drm_global_mutex);
- retcode = func(dev, kdata, file_priv);
- mutex_unlock(&drm_global_mutex);
}
+ if (asize > usize)
+ memset(kdata + usize, 0, asize - usize);
+ }
- if (cmd & IOC_OUT) {
- if (copy_to_user((void __user *)arg, kdata,
- usize) != 0)
- retcode = -EFAULT;
+ if (cmd & IOC_IN) {
+ if (copy_from_user(kdata, (void __user *)arg,
+ usize) != 0) {
+ retcode = -EFAULT;
+ goto err_i1;
}
+ } else
+ memset(kdata, 0, usize);
+
+ if (ioctl->flags & DRM_UNLOCKED)
+ retcode = func(dev, kdata, file_priv);
+ else {
+ mutex_lock(&drm_global_mutex);
+ retcode = func(dev, kdata, file_priv);
+ mutex_unlock(&drm_global_mutex);
+ }
+
+ if (cmd & IOC_OUT) {
+ if (copy_to_user((void __user *)arg, kdata,
+ usize) != 0)
+ retcode = -EFAULT;
}
err_i1:
--
1.7.10.4
