[PATCH v3 1/3] udmabuf: add documentation

[PATCH v3 1/3] udmabuf: add documentation

[Gerd Hoffmann]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/uapi/linux/udmabuf.h         | 51 +++++++++++++++++++++++++++++++++---
 Documentation/driver-api/dma-buf.rst |  8 ++++++
 2 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/udmabuf.h b/include/uapi/linux/udmabuf.h
index 46b6532ed8..281e2c52f1 100644
--- a/include/uapi/linux/udmabuf.h
+++ b/include/uapi/linux/udmabuf.h
@@ -5,8 +5,39 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 
+/**
+ * DOC: udmabuf
+ *
+ * udmabuf is a device driver which allows userspace to create
+ * dmabufs.  The memory used for these dmabufs must be backed by
+ * memfd.  The memfd must have F_SEAL_SHRINK and it must not have
+ * F_SEAL_WRITE.
+ *
+ * The driver has two ioctls, one to create a dmabuf from a single
+ * memory block and one to create a dmabuf from a list of memory
+ * blocks.
+ *
+ * UDMABUF_CREATE - _IOW('u', 0x42, udmabuf_create)
+ *
+ * UDMABUF_CREATE_LIST - _IOW('u', 0x43, udmabuf_create_list)
+ */
+
+#define UDMABUF_CREATE       _IOW('u', 0x42, struct udmabuf_create)
+#define UDMABUF_CREATE_LIST  _IOW('u', 0x43, struct udmabuf_create_list)
+
 #define UDMABUF_FLAGS_CLOEXEC	0x01
 
+/**
+ * struct udmabuf_create - create a dmabuf from a single memory block.
+ *
+ * @memfd: The file handle.
+ * @offset: Start of the buffer (from memfd start).
+ * Must be page aligned.
+ * @size: Size of the buffer.  Must be rounded to page size.
+ *
+ * @flags:
+ * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf.
+ */
 struct udmabuf_create {
 	__u32 memfd;
 	__u32 flags;
@@ -14,6 +45,14 @@ struct udmabuf_create {
 	__u64 size;
 };
 
+/**
+ * struct udmabuf_create_item - one memory block list item.
+ *
+ * @memfd: The file handle.
+ * @offset: Start of the buffer (from memfd start).
+ * Must be page aligned.
+ * @size: Size of the buffer.  Must be rounded to page size.
+ */
 struct udmabuf_create_item {
 	__u32 memfd;
 	__u32 __pad;
@@ -21,13 +60,19 @@ struct udmabuf_create_item {
 	__u64 size;
 };
 
+/**
+ * struct udmabuf_create_list - create a dmabuf from a memory block list.
+ *
+ * @count: The number of list elements.
+ * @list: The memory block list
+ *
+ * flags:
+ * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf.
+ */
 struct udmabuf_create_list {
 	__u32 flags;
 	__u32 count;
 	struct udmabuf_create_item list[];
 };
 
-#define UDMABUF_CREATE       _IOW('u', 0x42, struct udmabuf_create)
-#define UDMABUF_CREATE_LIST  _IOW('u', 0x43, struct udmabuf_create_list)
-
 #endif /* _UAPI_LINUX_UDMABUF_H */
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index b541e97c7a..1f62c30a14 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -166,3 +166,11 @@ DMA Fence uABI/Sync File
 .. kernel-doc:: include/linux/sync_file.h
    :internal:
 
+Userspace DMA Buffer driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/uapi/linux/udmabuf.h
+   :doc: udmabuf
+
+.. kernel-doc:: include/uapi/linux/udmabuf.h
+   :internal:
-- 
2.9.3

[PATCH v3 2/3] udmabuf: check that __pad is zero

[Gerd Hoffmann]

Reported-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/dma-buf/udmabuf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 9edabce0b8..964beadd11 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -134,6 +134,8 @@ static long udmabuf_create(const struct udmabuf_create_list *head,
 
 	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
 	for (i = 0; i < head->count; i++) {
+		if (list[i].__pad)
+			goto err;
 		if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
 			goto err;
 		if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
-- 
2.9.3

[PATCH v3 3/3] udmabuf: check that flags has no unsupported bits set

[Gerd Hoffmann]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reported-by: Yann Droneaud <ydroneaud@opteya.com>
---
 drivers/dma-buf/udmabuf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 964beadd11..acd97670c5 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -128,6 +128,9 @@ static long udmabuf_create(const struct udmabuf_create_list *head,
 	int seals, ret = -EINVAL;
 	u32 i, flags;
 
+	if (head->flags & ~UDMABUF_FLAGS_CLOEXEC)
+		return -EINVAL;
+
 	ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
 	if (!ubuf)
 		return -ENOMEM;
-- 
2.9.3

Re: [PATCH v3 1/3] udmabuf: add documentation

[Randy Dunlap]

Hi Gerd,

Missed one from yesterday:

On 9/11/18 11:33 PM, Gerd Hoffmann wrote:
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  include/uapi/linux/udmabuf.h         | 51 +++++++++++++++++++++++++++++++++---
>  Documentation/driver-api/dma-buf.rst |  8 ++++++
>  2 files changed, 56 insertions(+), 3 deletions(-)
> 
> diff --git a/include/uapi/linux/udmabuf.h b/include/uapi/linux/udmabuf.h
> index 46b6532ed8..281e2c52f1 100644
> --- a/include/uapi/linux/udmabuf.h
> +++ b/include/uapi/linux/udmabuf.h
> @@ -5,8 +5,39 @@
>  #include <linux/types.h>
>  #include <linux/ioctl.h>
>  
> +/**
> + * DOC: udmabuf
> + *
> + * udmabuf is a device driver which allows userspace to create
> + * dmabufs.  The memory used for these dmabufs must be backed by
> + * memfd.  The memfd must have F_SEAL_SHRINK and it must not have
> + * F_SEAL_WRITE.
> + *
> + * The driver has two ioctls, one to create a dmabuf from a single
> + * memory block and one to create a dmabuf from a list of memory
> + * blocks.
> + *
> + * UDMABUF_CREATE - _IOW('u', 0x42, udmabuf_create)
> + *
> + * UDMABUF_CREATE_LIST - _IOW('u', 0x43, udmabuf_create_list)
> + */
> +
> +#define UDMABUF_CREATE       _IOW('u', 0x42, struct udmabuf_create)
> +#define UDMABUF_CREATE_LIST  _IOW('u', 0x43, struct udmabuf_create_list)
> +
>  #define UDMABUF_FLAGS_CLOEXEC	0x01
>  
> +/**
> + * struct udmabuf_create - create a dmabuf from a single memory block.
> + *
> + * @memfd: The file handle.
> + * @offset: Start of the buffer (from memfd start).
> + * Must be page aligned.
> + * @size: Size of the buffer.  Must be rounded to page size.
> + *
> + * @flags:
> + * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf.
> + */
>  struct udmabuf_create {
>  	__u32 memfd;
>  	__u32 flags;
> @@ -14,6 +45,14 @@ struct udmabuf_create {
>  	__u64 size;
>  };
>  
> +/**
> + * struct udmabuf_create_item - one memory block list item.
> + *
> + * @memfd: The file handle.
> + * @offset: Start of the buffer (from memfd start).
> + * Must be page aligned.
> + * @size: Size of the buffer.  Must be rounded to page size.
> + */
>  struct udmabuf_create_item {
>  	__u32 memfd;
>  	__u32 __pad;
> @@ -21,13 +60,19 @@ struct udmabuf_create_item {
>  	__u64 size;
>  };
>  
> +/**
> + * struct udmabuf_create_list - create a dmabuf from a memory block list.
> + *
> + * @count: The number of list elements.
> + * @list: The memory block list
> + *
> + * flags:

      @flags:

> + * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf.
> + */
>  struct udmabuf_create_list {
>  	__u32 flags;
>  	__u32 count;
>  	struct udmabuf_create_item list[];
>  };

-- 
~Randy