Re: [PATCH 11/14] media: medkatek: vcodec: covert secure fd to secure handle

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Le mardi 19 septembre 2023 à 15:38 -0700, Jeffrey Kardatzke a écrit :
> On Tue, Sep 19, 2023 at 12:43 PM Nicolas Dufresne
> <nicolas.dufresne@collabora.com> wrote:
> > 
> > Le lundi 11 septembre 2023 à 20:59 +0800, Yunfei Dong a écrit :
> > > User driver will fill or parse data in optee-os with secure handle,
> > > need to covert secure fd to secure handle in kernel.
> > > 
> > > Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
> > > ---
> > >  .../vcodec/decoder/mtk_vcodec_dec_drv.c       |  1 +
> > >  .../vcodec/decoder/mtk_vcodec_dec_stateless.c | 54 ++++++++++++++++++-
> > >  drivers/media/v4l2-core/v4l2-ctrls-defs.c     |  5 ++
> > >  include/uapi/linux/v4l2-controls.h            |  4 ++
> > >  4 files changed, 62 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> > > index 0a89ce452ac3..64e006820f43 100644
> > > --- a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> > > +++ b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> > > @@ -571,3 +571,4 @@ module_platform_driver(mtk_vcodec_dec_driver);
> > > 
> > >  MODULE_LICENSE("GPL v2");
> > >  MODULE_DESCRIPTION("Mediatek video codec V4L2 decoder driver");
> > > +MODULE_IMPORT_NS(DMA_BUF);
> > > diff --git a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateless.c b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateless.c
> > > index 2ea517883a86..d2b09ce9f1cf 100644
> > > --- a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateless.c
> > > +++ b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateless.c
> > > @@ -426,6 +426,46 @@ static int mtk_vcodec_get_pic_info(struct mtk_vcodec_dec_ctx *ctx)
> > >       return ret;
> > >  }
> > > 
> > > +static int mtk_dma_contig_get_secure_handle(struct mtk_vcodec_dec_ctx *ctx, int fd)
> > > +{
> > > +     int secure_handle = 0;
> > > +     struct dma_buf *buf;
> > > +     struct dma_buf_attachment *dba;
> > > +     struct sg_table *sgt;
> > > +     struct device *dev = &ctx->dev->plat_dev->dev;
> > > +
> > > +     buf = dma_buf_get(fd);
> > > +     if (IS_ERR(buf)) {
> > > +             mtk_v4l2_vdec_err(ctx, "dma_buf_get fail fd:%d", fd);
> > > +             return 0;
> > > +     }
> > > +
> > > +     dba = dma_buf_attach(buf, dev);
> > > +     if (IS_ERR(dba)) {
> > > +             mtk_v4l2_vdec_err(ctx, "dma_buf_attach fail fd:%d", fd);
> > > +             goto err_attach;
> > > +     }
> > > +
> > > +     sgt = dma_buf_map_attachment(dba, DMA_BIDIRECTIONAL);
> > > +     if (IS_ERR(sgt)) {
> > > +             mtk_v4l2_vdec_err(ctx, "dma_buf_map_attachment fail fd:%d", fd);
> > > +             goto err_map;
> > > +     }
> > > +     secure_handle = sg_dma_address(sgt->sgl);
> > 
> > Does it mean if your secure dmabuf is passed to a driver that didn't know it was
> > secure it will pick the handle as a memory address and program the HW with it ?
> > That seems unsafe, the handle should be stored in a dedicated place and mapping
> > should either fail, or provide a dummy buffer.
> 
> Since the secure dmabufs don't support any mmap/cpu access to them and
> return -EPERM in those cases; wouldn't that prevent misuse of them in
> other places? (so the mmap operation and CPU access will fail, but
> getting the SG list from the dmabuf succeeds)

My impression is that if userspace can pass this FD to a driver without telling
the driver it is secure memory, the driver may potentially crash trying to use
the handle as an memory address.

In my opinion, sg_dma_address() should return addresses, like its name state. If
you want to get something else, you should find another way to obtain it.

Nicolas

> 
> > 
> > > +
> > > +     dma_buf_unmap_attachment(dba, sgt, DMA_BIDIRECTIONAL);
> > > +     dma_buf_detach(buf, dba);
> > > +     dma_buf_put(buf);
> > > +
> > > +     return secure_handle;
> > > +err_map:
> > > +     dma_buf_detach(buf, dba);
> > > +err_attach:
> > > +     dma_buf_put(buf);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > >  static int mtk_vdec_s_ctrl(struct v4l2_ctrl *ctrl)
> > >  {
> > >       struct mtk_vcodec_dec_ctx *ctx = ctrl_to_dec_ctx(ctrl);
> > > @@ -436,7 +476,7 @@ static int mtk_vdec_s_ctrl(struct v4l2_ctrl *ctrl)
> > >       struct v4l2_ctrl *hdr_ctrl;
> > >       const struct mtk_vcodec_dec_pdata *dec_pdata = ctx->dev->vdec_pdata;
> > >       const struct mtk_video_fmt *fmt;
> > > -     int i = 0, ret = 0;
> > > +     int i = 0, ret = 0, sec_fd;
> > > 
> > >       hdr_ctrl = ctrl;
> > >       if (!hdr_ctrl || !hdr_ctrl->p_new.p)
> > > @@ -489,6 +529,12 @@ static int mtk_vdec_s_ctrl(struct v4l2_ctrl *ctrl)
> > >                       return -EINVAL;
> > >               }
> > >               break;
> > > +     case V4L2_CID_MPEG_MTK_GET_SECURE_HANDLE:
> > > +             sec_fd = ctrl->val;
> > > +
> > > +             ctrl->val = mtk_dma_contig_get_secure_handle(ctx, ctrl->val);
> > > +             mtk_v4l2_vdec_dbg(3, ctx, "get secure handle: %d => 0x%x", sec_fd, ctrl->val);
> > > +             break;
> > >       default:
> > >               mtk_v4l2_vdec_dbg(3, ctx, "Not supported to set ctrl id: 0x%x\n", hdr_ctrl->id);
> > >               return ret;
> > > @@ -525,8 +571,9 @@ static const struct v4l2_ctrl_ops mtk_vcodec_dec_ctrl_ops = {
> > >  static int mtk_vcodec_dec_ctrls_setup(struct mtk_vcodec_dec_ctx *ctx)
> > >  {
> > >       unsigned int i;
> > > +     struct v4l2_ctrl *ctrl;
> > > 
> > > -     v4l2_ctrl_handler_init(&ctx->ctrl_hdl, NUM_CTRLS);
> > > +     v4l2_ctrl_handler_init(&ctx->ctrl_hdl, NUM_CTRLS + 1);
> > >       if (ctx->ctrl_hdl.error) {
> > >               mtk_v4l2_vdec_err(ctx, "v4l2_ctrl_handler_init failed\n");
> > >               return ctx->ctrl_hdl.error;
> > > @@ -543,6 +590,9 @@ static int mtk_vcodec_dec_ctrls_setup(struct mtk_vcodec_dec_ctx *ctx)
> > >               }
> > >       }
> > > 
> > > +     ctrl = v4l2_ctrl_new_std(&ctx->ctrl_hdl, &mtk_vcodec_dec_ctrl_ops,
> > > +                              V4L2_CID_MPEG_MTK_GET_SECURE_HANDLE, 0, 65535, 1, 0);
> > > +
> > >       v4l2_ctrl_handler_setup(&ctx->ctrl_hdl);
> > > 
> > >       return 0;
> > > diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > > index 8696eb1cdd61..d8cf01f76aab 100644
> > > --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > > +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > > @@ -1041,6 +1041,7 @@ const char *v4l2_ctrl_get_name(u32 id)
> > >       case V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD:     return "HEVC Size of Length Field";
> > >       case V4L2_CID_MPEG_VIDEO_REF_NUMBER_FOR_PFRAMES:        return "Reference Frames for a P-Frame";
> > >       case V4L2_CID_MPEG_VIDEO_PREPEND_SPSPPS_TO_IDR:         return "Prepend SPS and PPS to IDR";
> > > +     case V4L2_CID_MPEG_MTK_GET_SECURE_HANDLE:               return "MediaTek Decoder get secure handle";
> > > 
> > >       /* AV1 controls */
> > >       case V4L2_CID_MPEG_VIDEO_AV1_PROFILE:                   return "AV1 Profile";
> > > @@ -1437,6 +1438,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> > >       case V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES:
> > >               *type = V4L2_CTRL_TYPE_INTEGER_MENU;
> > >               break;
> > > +     case V4L2_CID_MPEG_MTK_GET_SECURE_HANDLE:
> > > +             *type = V4L2_CTRL_TYPE_INTEGER;
> > > +             *flags |= V4L2_CTRL_FLAG_WRITE_ONLY;
> > > +             break;
> > >       case V4L2_CID_USER_CLASS:
> > >       case V4L2_CID_CAMERA_CLASS:
> > >       case V4L2_CID_CODEC_CLASS:
> > > diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> > > index c3604a0a3e30..7b3694985366 100644
> > > --- a/include/uapi/linux/v4l2-controls.h
> > > +++ b/include/uapi/linux/v4l2-controls.h
> > > @@ -954,6 +954,10 @@ enum v4l2_mpeg_mfc51_video_force_frame_type {
> > >  #define V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC            (V4L2_CID_CODEC_MFC51_BASE+53)
> > >  #define V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P             (V4L2_CID_CODEC_MFC51_BASE+54)
> > > 
> > > +/*  MPEG-class control IDs specific to the MediaTek Decoder driver as defined by V4L2 */
> > > +#define V4L2_CID_MPEG_MTK_BASE                       (V4L2_CTRL_CLASS_CODEC | 0x2000)
> > > +#define V4L2_CID_MPEG_MTK_GET_SECURE_HANDLE  (V4L2_CID_MPEG_MTK_BASE+8)
> > > +
> > >  /*  Camera class control IDs */
> > > 
> > >  #define V4L2_CID_CAMERA_CLASS_BASE   (V4L2_CTRL_CLASS_CAMERA | 0x900)
> >