Support the request argument of the QBUF ioctl.

Signed-off-by: Alexandre Courbot <acour...@chromium.org>
---
 drivers/media/v4l2-core/v4l2-ioctl.c | 83 +++++++++++++++++++++++++++++++++++-
 1 file changed, 82 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c 
b/drivers/media/v4l2-core/v4l2-ioctl.c
index fdd2f784c264..3b44f1fe4f23 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -29,6 +29,7 @@
 #include <media/v4l2-device.h>
 #include <media/videobuf2-v4l2.h>
 #include <media/v4l2-mc.h>
+#include <media/media-request.h>
 
 #include <trace/events/v4l2.h>
 
@@ -965,6 +966,71 @@ static int check_fmt(struct file *file, enum v4l2_buf_type 
type)
        return -EINVAL;
 }
 
+/*
+ * Validate that a given request can be used during an ioctl.
+ *
+ * When using the request API, request file descriptors must be matched against
+ * the actual request object. User-space can pass any file descriptor, so we
+ * need to make sure the call is valid before going further.
+ *
+ * This function looks up the request and associated data and performs the
+ * following sanity checks:
+ *
+ * * Make sure that the entity belongs to the media_device managing the passed
+ *   request,
+ * * Make sure that the entity data (if any) is associated to the current file
+ *   handler.
+ *
+ * This function returns a pointer to the valid request, or and error code in
+ * case of failure. When successful, a reference to the request is acquired and
+ * must be properly released by the caller. If _data is not NULL, then it is
+ * filled with a pointer to the corresponding entity data.
+ */
+#ifdef CONFIG_MEDIA_CONTROLLER
+static struct media_request *
+check_request(int request, struct file *file, void *fh, struct 
media_request_entity_data **_data)
+{
+       struct media_request *req = NULL;
+       struct video_device *vfd = video_devdata(file);
+       struct v4l2_fh *vfh =
+               test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
+       struct media_entity *entity = &vfd->entity;
+       struct media_request_entity_data *data;
+
+       if (!entity)
+               return ERR_PTR(-EINVAL);
+
+       req = media_request_get_from_fd(request);
+       if (!req)
+               return ERR_PTR(-EINVAL);
+
+       /* Validate that the entity belongs to the correct media_device */
+       if (vfd->v4l2_dev->mdev->req_mgr != req->mgr) {
+               media_request_put(req);
+               return ERR_PTR(-EINVAL);
+       }
+
+       /* Validate that the entity's data belongs to the correct fh */
+       data = media_request_get_entity_data(req, entity, vfh);
+       if (IS_ERR(data)) {
+               media_request_put(req);
+               return ERR_PTR(PTR_ERR(data));
+       }
+
+       if (_data)
+               *_data = data;
+
+       return req;
+}
+#else /* CONFIG_MEDIA_CONTROLLER */
+static struct media_request *
+check_request(int request, struct file *file, void *fh)
+{
+       return ERR_PTR(-ENOSYS);
+}
+
+#endif /* CONFIG_MEDIA_CONTROLLER */
+
 static void v4l_sanitize_format(struct v4l2_format *fmt)
 {
        unsigned int offset;
@@ -1902,10 +1968,25 @@ static int v4l_querybuf(const struct v4l2_ioctl_ops 
*ops,
 static int v4l_qbuf(const struct v4l2_ioctl_ops *ops,
                                struct file *file, void *fh, void *arg)
 {
+       struct media_request *req = NULL;
        struct v4l2_buffer *p = arg;
        int ret = check_fmt(file, p->type);
 
-       return ret ? ret : ops->vidioc_qbuf(file, fh, p);
+       if (ret)
+               return ret;
+
+       if (p->request_fd > 0) {
+               req = check_request(p->request_fd, file, fh, NULL);
+               if (IS_ERR(req))
+                       return PTR_ERR(req);
+       }
+
+       ret = ops->vidioc_qbuf(file, fh, p);
+
+       if (req)
+               media_request_put(req);
+
+       return ret;
 }
 
 static int v4l_dqbuf(const struct v4l2_ioctl_ops *ops,
-- 
2.16.0.rc1.238.g530d649a79-goog

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