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drm/gem: implement vma access management

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We implement automatic vma mmap() access management for all drivers using
gem_mmap. We use the vma manager to add each open-file that creates a
gem-handle to the vma-node of the underlying gem object. Once the handle
is destroyed, we drop the open-file again.

This allows us to use drm_vma_node_is_allowed() on _any_ gem object to see
whether an open-file is granted access. In drm_gem_mmap() we use this to
verify that unprivileged users cannot guess gem offsets and map arbitrary
buffers.

Note that this manages access for _all_ gem users (also TTM+GEM), but the
actual access checks are only done for drm_gem_mmap(). TTM drivers use the
TTM mmap helpers, which need to do that separately.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
David Herrmann 2013-08-25 18:28:58 +02:00 committed by Dave Airlie
parent 88d7ebe593
commit ca481c9b2a
1 changed files with 17 additions and 0 deletions
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17
drivers/gpu/drm/drm_gem.c
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@ -298,6 +298,7 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
spin_unlock(&filp->table_lock);
drm_gem_remove_prime_handles(obj, filp);
drm_vma_node_revoke(&obj->vma_node, filp->filp);
if (dev->driver->gem_close_object)
dev->driver->gem_close_object(obj, filp);
@ -357,6 +358,11 @@ drm_gem_handle_create_tail(struct drm_file *file_priv,
}
*handlep = ret;
ret = drm_vma_node_allow(&obj->vma_node, file_priv->filp);
if (ret) {
drm_gem_handle_delete(file_priv, *handlep);
return ret;
}
if (dev->driver->gem_open_object) {
ret = dev->driver->gem_open_object(obj, file_priv);
@ -701,6 +707,7 @@ drm_gem_object_release_handle(int id, void *ptr, void *data)
struct drm_device *dev = obj->dev;
drm_gem_remove_prime_handles(obj, file_priv);
drm_vma_node_revoke(&obj->vma_node, file_priv->filp);
if (dev->driver->gem_close_object)
dev->driver->gem_close_object(obj, file_priv);
@ -793,6 +800,10 @@ EXPORT_SYMBOL(drm_gem_vm_close);
* the GEM object is not looked up based on its fake offset. To implement the
* DRM mmap operation, drivers should use the drm_gem_mmap() function.
*
* drm_gem_mmap_obj() assumes the user is granted access to the buffer while
* drm_gem_mmap() prevents unprivileged users from mapping random objects. So
* callers must verify access restrictions before calling this helper.
*
* NOTE: This function has to be protected with dev->struct_mutex
*
* Return 0 or success or -EINVAL if the object size is smaller than the VMA
@ -841,6 +852,9 @@ EXPORT_SYMBOL(drm_gem_mmap_obj);
* Look up the GEM object based on the offset passed in (vma->vm_pgoff will
* contain the fake offset we created when the GTT map ioctl was called on
* the object) and map it with a call to drm_gem_mmap_obj().
*
* If the caller is not granted access to the buffer object, the mmap will fail
* with EACCES. Please see the vma manager for more information.
*/
int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
{
@ -861,6 +875,9 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
if (!node) {
mutex_unlock(&dev->struct_mutex);
return drm_mmap(filp, vma);
} else if (!drm_vma_node_is_allowed(node, filp)) {
mutex_unlock(&dev->struct_mutex);
return -EACCES;
}
obj = container_of(node, struct drm_gem_object, vma_node);