Am 20.05.24 um 09:58 schrieb Yong Wu (吴勇):
On Thu, 2024-05-16 at 10:17 +0200, Christian König wrote:
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Am 15.05.24 um 13:23 schrieb Yong Wu:
Introduce a FLAG for the restricted memory which means the memory
is
protected by TEE or hypervisor, then it's inaccessiable for kernel.
Currently we don't use sg_dma_unmark_restricted, thus this
interface
has not been added.
Why should that be part of the scatterlist? It doesn't seem to
affect
any of it's functionality.
As far as I can see the scatterlist shouldn't be the transport of
this
kind of information.
Thanks for the review. I will remove this.
In our user scenario, DRM will import these buffers and check if this
is a restricted buffer. If yes, it will use secure GCE takes over.
If this judgment is not suitable to be placed in scatterlist. I don't
know if it is ok to limit this inside dma-buf. Adding such an
interface:
static bool dma_buf_is_restricted(struct dma_buf *dmabuf)
{
return !strncmp(dmabuf->exp_name, "restricted", 10);
}
No, usually stuff like that doesn't belong into DMA buf either.
Question here really is who controls the security status of the memory
backing the buffer?
In other words who tells the exporter that it should allocate and fill a
buffer with encrypted data?
If that is userspace then that is part of the format information and it
is also userspace who should tell the importer that it needs to work
with encrypted data.
The kernel is intentionally not involved in stuff like that.
Regards,
Christian.
Thanks.
Regards,
Christian.
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
---
include/linux/scatterlist.h | 34
++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/include/linux/scatterlist.h
b/include/linux/scatterlist.h
index 77df3d7b18a6..a6ad9018eca0 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -282,6 +282,7 @@ static inline void sg_unmark_end(struct
scatterlist *sg)
#define SG_DMA_BUS_ADDRESS(1 << 0)
#define SG_DMA_SWIOTLB(1 << 1)
+#define SG_DMA_RESTRICTED(2 << 1)
/**
* sg_dma_is_bus_address - Return whether a given segment was
marked
@@ -352,6 +353,31 @@ static inline void sg_dma_mark_swiotlb(struct
scatterlist *sg)
sg->dma_flags |= SG_DMA_SWIOTLB;
}
+/**
+ * sg_dma_mark_restricted - Mark the scatterlist for restricted
buffer.
+ * @sg:SG entry
+ *
+ * Description:
+ * Marks a a scatterlist for the restricted buffer that may be
inaccessiable
+ * in kernel if it is protected.
+ */
+static inline void sg_dma_mark_restricted(struct scatterlist *sg)
+{
+sg->dma_flags |= SG_DMA_RESTRICTED;
+}
+
+/**
+ * sg_dma_is_restricted - Return whether the scatterlist was
marked as restricted
+ * buffer.
+ * @sg:SG entry
+ *
+ * Description:
+ * Returns true if the scatterlist was marked as restricted
buffer.
+ */
+static inline bool sg_dma_is_restricted(struct scatterlist *sg)
+{
+return sg->dma_flags & SG_DMA_RESTRICTED;
+}
#else
static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
@@ -372,6 +398,14 @@ static inline void sg_dma_mark_swiotlb(struct
scatterlist *sg)
{
}
+static inline bool sg_dma_is_restricted(struct scatterlist *sg)
+{
+return false;
+}
+
+static inline void sg_dma_mark_restrited(struct scatterlist *sg)
+{
+}
#endif/* CONFIG_NEED_SG_DMA_FLAGS */
/**
