Re: [PATCH v2 2/8] dma-buf: heaps: secure_heap: Add private heap ops

[Jeffrey Kardatzke]

On Sat, Nov 11, 2023 at 3:16 AM Yong Wu <yong.wu@xxxxxxxxxxxx> wrote:
>
> For the secure memory, there are two steps:
> a) Allocate buffers in kernel side;
> b) Secure that buffer.
> Different heaps may have different buffer allocation methods and
> different memory protection methods. Here abstract the memory
> allocation and securing operations.
>
> Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> ---
>  drivers/dma-buf/heaps/secure_heap.c | 58 ++++++++++++++++++++++++++++-
>  1 file changed, 57 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
> index a634051a0a67..87ac23072e9e 100644
> --- a/drivers/dma-buf/heaps/secure_heap.c
> +++ b/drivers/dma-buf/heaps/secure_heap.c
> @@ -24,15 +24,66 @@ struct secure_buffer {
>         size_t                          size;
>  };
>
> +struct secure_heap;
> +
> +struct secure_heap_prv_data {
> +       int     (*memory_alloc)(struct secure_heap *sec_heap, struct secure_buffer *sec_buf);
> +       void    (*memory_free)(struct secure_heap *sec_heap, struct secure_buffer *sec_buf);
> +
> +       /* Protect/unprotect the memory */
> +       int     (*secure_the_memory)(struct secure_heap *sec_heap, struct secure_buffer *sec_buf);
> +       void    (*unsecure_the_memory)(struct secure_heap *sec_heap, struct secure_buffer *sec_buf);
> +};
Move these into dma-heap-secure.h per the comments on the prior patch.

> +
>  struct secure_heap {
>         const char                      *name;
>         const enum secure_memory_type   mem_type;
> +
> +       const struct secure_heap_prv_data *data;
>  };
>
> +static int secure_heap_secure_memory_allocate(struct secure_heap *sec_heap,
> +                                             struct secure_buffer *sec_buf)
> +{
> +       const struct secure_heap_prv_data *data = sec_heap->data;
> +       int ret;
> +
> +       if (data->memory_alloc) {
> +               ret = data->memory_alloc(sec_heap, sec_buf);
> +               if (ret)
> +                       return ret;
> +       }
You should probably always require that memory_alloc is defined
(secure_the_memory can be optional, as that may be part of the
allocation).
> +
> +       if (data->secure_the_memory) {
> +               ret = data->secure_the_memory(sec_heap, sec_buf);
> +               if (ret)
> +                       goto sec_memory_free;
> +       }
> +       return 0;
> +
> +sec_memory_free:
> +       if (data->memory_free)
> +               data->memory_free(sec_heap, sec_buf);
You should probably always require that memory_free is defined.
> +       return ret;
> +}
> +
> +static void secure_heap_secure_memory_free(struct secure_heap *sec_heap,
> +                                          struct secure_buffer *sec_buf)
> +{
> +       const struct secure_heap_prv_data *data = sec_heap->data;
> +
> +       if (data->unsecure_the_memory)
> +               data->unsecure_the_memory(sec_heap, sec_buf);
> +
> +       if (data->memory_free)
> +               data->memory_free(sec_heap, sec_buf);
You should probably always require that memory_free is defined.
> +}
> +
>  static struct dma_buf *
>  secure_heap_allocate(struct dma_heap *heap, unsigned long size,
>                      unsigned long fd_flags, unsigned long heap_flags)
>  {
> +       struct secure_heap *sec_heap = dma_heap_get_drvdata(heap);
>         struct secure_buffer *sec_buf;
>         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
>         struct dma_buf *dmabuf;
> @@ -45,6 +96,9 @@ secure_heap_allocate(struct dma_heap *heap, unsigned long size,
>         sec_buf->size = ALIGN(size, PAGE_SIZE);
>         sec_buf->heap = heap;
>
> +       ret = secure_heap_secure_memory_allocate(sec_heap, sec_buf);
> +       if (ret)
> +               goto err_free_buf;
>         exp_info.exp_name = dma_heap_get_name(heap);
>         exp_info.size = sec_buf->size;
>         exp_info.flags = fd_flags;
> @@ -53,11 +107,13 @@ secure_heap_allocate(struct dma_heap *heap, unsigned long size,
>         dmabuf = dma_buf_export(&exp_info);
>         if (IS_ERR(dmabuf)) {
>                 ret = PTR_ERR(dmabuf);
> -               goto err_free_buf;
> +               goto err_free_sec_mem;
>         }
>
>         return dmabuf;
>
> +err_free_sec_mem:
> +       secure_heap_secure_memory_free(sec_heap, sec_buf);
>  err_free_buf:
>         kfree(sec_buf);
>         return ERR_PTR(ret);
> --
> 2.25.1
>