[PATCH 3.16 106/178] drm/ttm, drm/vmwgfx: Relax permission checking when opening surfaces

From: Ben Hutchings
Date: Sun Jul 16 2017 - 10:16:00 EST


3.16.46-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Thomas Hellstrom <thellstrom@xxxxxxxxxx>

commit fe25deb7737ce6c0879ccf79c99fa1221d428bf2 upstream.

Previously, when a surface was opened using a legacy (non prime) handle,
it was verified to have been created by a client in the same master realm.
Relax this so that opening is also allowed recursively if the client
already has the surface open.

This works around a regression in svga mesa where opening of a shared
surface is used recursively to obtain surface information.

Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Reviewed-by: Sinclair Yeh <syeh@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_object.c | 10 +++++++---
drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 6 ++----
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 4 ++--
drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 22 +++++++++-------------
include/drm/ttm/ttm_object.h | 5 ++++-
5 files changed, 24 insertions(+), 23 deletions(-)

--- a/drivers/gpu/drm/ttm/ttm_object.c
+++ b/drivers/gpu/drm/ttm/ttm_object.c
@@ -179,7 +179,7 @@ int ttm_base_object_init(struct ttm_obje
if (unlikely(ret != 0))
goto out_err0;

- ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
+ ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);
if (unlikely(ret != 0))
goto out_err1;

@@ -318,7 +318,8 @@ EXPORT_SYMBOL(ttm_ref_object_exists);

int ttm_ref_object_add(struct ttm_object_file *tfile,
struct ttm_base_object *base,
- enum ttm_ref_type ref_type, bool *existed)
+ enum ttm_ref_type ref_type, bool *existed,
+ bool require_existed)
{
struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
struct ttm_ref_object *ref;
@@ -345,6 +346,9 @@ int ttm_ref_object_add(struct ttm_object
}

rcu_read_unlock();
+ if (require_existed)
+ return -EPERM;
+
ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),
false, false);
if (unlikely(ret != 0))
@@ -635,7 +639,7 @@ int ttm_prime_fd_to_handle(struct ttm_ob
prime = (struct ttm_prime_object *) dma_buf->priv;
base = &prime->base;
*handle = base->hash.key;
- ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
+ ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);

dma_buf_put(dma_buf);

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -1103,10 +1103,8 @@ int vmw_fence_event_ioctl(struct drm_dev
(void) vmw_fence_obj_reference(fence);

if (user_fence_rep != NULL) {
- bool existed;
-
- ret = ttm_ref_object_add(tfile, base,
- TTM_REF_USAGE, &existed);
+ ret = ttm_ref_object_add(vmw_fp->tfile, base,
+ TTM_REF_USAGE, NULL, false);
if (unlikely(ret != 0)) {
DRM_ERROR("Failed to reference a fence "
"object.\n");
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -587,7 +587,7 @@ static int vmw_user_dmabuf_synccpu_grab(
return ret;

ret = ttm_ref_object_add(tfile, &user_bo->prime.base,
- TTM_REF_SYNCCPU_WRITE, &existed);
+ TTM_REF_SYNCCPU_WRITE, &existed, false);
if (ret != 0 || existed)
ttm_bo_synccpu_write_release(&user_bo->dma.base);

@@ -771,7 +771,7 @@ int vmw_user_dmabuf_reference(struct ttm

*handle = user_bo->prime.base.hash.key;
return ttm_ref_object_add(tfile, &user_bo->prime.base,
- TTM_REF_USAGE, NULL);
+ TTM_REF_USAGE, NULL, false);
}

/*
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -902,17 +902,16 @@ vmw_surface_handle_reference(struct vmw_
uint32_t handle;
struct ttm_base_object *base;
int ret;
+ bool require_exist = false;

if (handle_type == DRM_VMW_HANDLE_PRIME) {
ret = ttm_prime_fd_to_handle(tfile, u_handle, &handle);
if (unlikely(ret != 0))
return ret;
} else {
- if (unlikely(drm_is_render_client(file_priv))) {
- DRM_ERROR("Render client refused legacy "
- "surface reference.\n");
- return -EACCES;
- }
+ if (unlikely(drm_is_render_client(file_priv)))
+ require_exist = true;
+
handle = u_handle;
}

@@ -934,17 +933,14 @@ vmw_surface_handle_reference(struct vmw_

/*
* Make sure the surface creator has the same
- * authenticating master.
+ * authenticating master, or is already registered with us.
*/
if (drm_is_primary_client(file_priv) &&
- user_srf->master != file_priv->master) {
- DRM_ERROR("Trying to reference surface outside of"
- " master domain.\n");
- ret = -EACCES;
- goto out_bad_resource;
- }
+ user_srf->master != file_priv->master)
+ require_exist = true;

- ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
+ ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL,
+ require_exist);
if (unlikely(ret != 0)) {
DRM_ERROR("Could not add a reference to a surface.\n");
goto out_bad_resource;
--- a/include/drm/ttm/ttm_object.h
+++ b/include/drm/ttm/ttm_object.h
@@ -229,6 +229,8 @@ extern void ttm_base_object_unref(struct
* @ref_type: The type of reference.
* @existed: Upon completion, indicates that an identical reference object
* already existed, and the refcount was upped on that object instead.
+ * @require_existed: Fail with -EPERM if an identical ref object didn't
+ * already exist.
*
* Checks that the base object is shareable and adds a ref object to it.
*
@@ -243,7 +245,8 @@ extern void ttm_base_object_unref(struct
*/
extern int ttm_ref_object_add(struct ttm_object_file *tfile,
struct ttm_base_object *base,
- enum ttm_ref_type ref_type, bool *existed);
+ enum ttm_ref_type ref_type, bool *existed,
+ bool require_existed);

extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,
struct ttm_base_object *base);