media: uvcvideo: Check controls flags before accessing them

We can figure out if reading/writing a set of controls can fail without
accessing them by checking their flags.

This way we can honor the API closer:

If an error is found when validating the list of controls passed with
VIDIOC_G_EXT_CTRLS, then error_idx shall be set to ctrls->count to
indicate to userspace that no actual hardware was touched.

Fixes v4l2-compliance:
Control ioctls (Input 0):
		warn: v4l2-test-controls.cpp(765): g_ext_ctrls(0) invalid error_idx 0
                fail: v4l2-test-controls.cpp(645): invalid error index write only control
        test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL

Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 2cc2ff0..18c315b 100644 (file)
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1042,6 +1042,28 @@ static int uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
        return 0;
 }
 
+int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
+                          bool read)
+{
+       struct uvc_control_mapping *mapping;
+       struct uvc_control *ctrl;
+
+       if (__uvc_query_v4l2_class(chain, v4l2_id, 0) >= 0)
+               return -EACCES;
+
+       ctrl = uvc_find_control(chain, v4l2_id, &mapping);
+       if (!ctrl)
+               return -EINVAL;
+
+       if (!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) && read)
+               return -EACCES;
+
+       if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) && !read)
+               return -EACCES;
+
+       return 0;
+}
+
 static const char *uvc_map_get_name(const struct uvc_control_mapping *map)
 {
        const char *name;

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index c6ec7dc..c10a638 100644 (file)
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -1003,6 +1003,26 @@ static int uvc_ioctl_query_ext_ctrl(struct file *file, void *fh,
        return 0;
 }
 
+static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
+                                struct v4l2_ext_controls *ctrls,
+                                unsigned long ioctl)
+{
+       struct v4l2_ext_control *ctrl = ctrls->controls;
+       unsigned int i;
+       int ret = 0;
+
+       for (i = 0; i < ctrls->count; ++ctrl, ++i) {
+               ret = uvc_ctrl_is_accessible(chain, ctrl->id,
+                                           ioctl == VIDIOC_G_EXT_CTRLS);
+               if (ret)
+                       break;
+       }
+
+       ctrls->error_idx = ioctl == VIDIOC_TRY_EXT_CTRLS ? i : ctrls->count;
+
+       return ret;
+}
+
 static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
                                 struct v4l2_ext_controls *ctrls)
 {
@@ -1012,6 +1032,10 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
        unsigned int i;
        int ret;
 
+       ret = uvc_ctrl_check_access(chain, ctrls, VIDIOC_G_EXT_CTRLS);
+       if (ret < 0)
+               return ret;
+
        if (ctrls->which == V4L2_CTRL_WHICH_DEF_VAL) {
                for (i = 0; i < ctrls->count; ++ctrl, ++i) {
                        struct v4l2_queryctrl qc = { .id = ctrl->id };
@@ -1048,13 +1072,17 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
 
 static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
                                     struct v4l2_ext_controls *ctrls,
-                                    bool commit)
+                                    unsigned long ioctl)
 {
        struct v4l2_ext_control *ctrl = ctrls->controls;
        struct uvc_video_chain *chain = handle->chain;
        unsigned int i;
        int ret;
 
+       ret = uvc_ctrl_check_access(chain, ctrls, ioctl);
+       if (ret < 0)
+               return ret;
+
        ret = uvc_ctrl_begin(chain);
        if (ret < 0)
                return ret;
@@ -1063,14 +1091,15 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
                ret = uvc_ctrl_set(handle, ctrl);
                if (ret < 0) {
                        uvc_ctrl_rollback(handle);
-                       ctrls->error_idx = commit ? ctrls->count : i;
+                       ctrls->error_idx = ioctl == VIDIOC_S_EXT_CTRLS ?
+                                                   ctrls->count : i;
                        return ret;
                }
        }
 
        ctrls->error_idx = 0;
 
-       if (commit)
+       if (ioctl == VIDIOC_S_EXT_CTRLS)
                return uvc_ctrl_commit(handle, ctrls->controls, ctrls->count);
        else
                return uvc_ctrl_rollback(handle);
@@ -1081,7 +1110,7 @@ static int uvc_ioctl_s_ext_ctrls(struct file *file, void *fh,
 {
        struct uvc_fh *handle = fh;
 
-       return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, true);
+       return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_S_EXT_CTRLS);
 }
 
 static int uvc_ioctl_try_ext_ctrls(struct file *file, void *fh,
@@ -1089,7 +1118,7 @@ static int uvc_ioctl_try_ext_ctrls(struct file *file, void *fh,
 {
        struct uvc_fh *handle = fh;
 
-       return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, false);
+       return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_TRY_EXT_CTRLS);
 }
 
 static int uvc_ioctl_querymenu(struct file *file, void *fh,

diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index b044d94..4aa7859 100644 (file)
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -901,6 +901,8 @@ static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
 
 int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
 int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
+int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
+                          bool read);
 
 int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
                      struct uvc_xu_control_query *xqry);