[PATCH v2 5/8] dma-buf: heaps: secure_heap: Add dma_ops

Yong Wu
2023-11-11T11:17:37Z

Add the dma_ops for this secure heap.
a) For secure buffer, cache_ops/mmap are not allowed, thus return
EPERM for them.
b) The secure buffer can't be accessed in kernel, thus it doesn't
have va/dma_address for it. Use the dma_address property to save the
"secure handle".

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
drivers/dma-buf/heaps/secure_heap.c | 120 ++++++++++++++++++++++++++++
1 file changed, 120 insertions(+)

diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
index 05062c14e7c7..25cc95442c56 100644
--- a/drivers/dma-buf/heaps/secure_heap.c
+++ b/drivers/dma-buf/heaps/secure_heap.c
@@ -9,6 +9,7 @@
#include <linux/dma-heap.h>
#include <linux/err.h>
#include <linux/module.h>
+#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>
#include <linux/uuid.h>
@@ -87,6 +88,10 @@ struct secure_heap {
const struct secure_heap_prv_data *data;
};

+struct secure_heap_attachment {
+ struct sg_table *table;
+};
+
static int tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
{
const struct secure_heap_prv_data *d = data;
@@ -238,6 +243,120 @@ static void secure_heap_secure_memory_free(struct secure_heap *sec_heap,
data->memory_free(sec_heap, sec_buf);
}

+static int secure_heap_attach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+ struct secure_buffer *sec_buf = dmabuf->priv;
+ struct secure_heap_attachment *a;
+ struct sg_table *table;
+ int ret;
+
+ a = kzalloc(sizeof(*a), GFP_KERNEL);
+ if (!a)
+ return -ENOMEM;
+
+ table = kzalloc(sizeof(*table), GFP_KERNEL);
+ if (!table) {
+ ret = -ENOMEM;
+ goto err_free_attach;
+ }
+
+ ret = sg_alloc_table(table, 1, GFP_KERNEL);
+ if (ret)
+ goto err_free_sgt;
+ sg_set_page(table->sgl, 0, sec_buf->size, 0);
+
+ a->table = table;
+ attachment->priv = a;
+
+ return 0;
+
+err_free_sgt:
+ kfree(table);
+err_free_attach:
+ kfree(a);
+ return ret;
+}
+
+static void secure_heap_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+ struct secure_heap_attachment *a = attachment->priv;
+
+ sg_free_table(a->table);
+ kfree(a->table);
+ kfree(a);
+}
+
+static struct sg_table *
+secure_heap_map_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction)
+{
+ struct secure_heap_attachment *a = attachment->priv;
+ struct dma_buf *dmabuf = attachment->dmabuf;
+ struct secure_buffer *sec_buf = dmabuf->priv;
+ struct sg_table *table = a->table;
+
+ /*
+ * Technically dma_address refers to the address used by HW, But for secure buffer
+ * we don't know its dma_address in kernel, Instead, we only know its "secure handle".
+ * Thus use this property to save the "secure handle", and the user will use it to
+ * obtain the real address in secure world.
+ *
+ * Note: CONFIG_DMA_API_DEBUG requires it to be aligned with PAGE_SIZE.
+ */
+ if (sec_buf->sec_handle) {
+ sg_dma_address(table->sgl) = sec_buf->sec_handle;
+ sg_dma_len(table->sgl) = sec_buf->size;
+ }
+ return table;
+}
+
+static void
+secure_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table,
+ enum dma_data_direction direction)
+{
+ struct secure_heap_attachment *a = attachment->priv;
+
+ WARN_ON(a->table != table);
+ sg_dma_address(table->sgl) = 0;
+ sg_dma_len(table->sgl) = 0;
+}
+
+static int
+secure_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+ return -EPERM;
+}
+
+static int
+secure_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+ return -EPERM;
+}
+
+static int secure_heap_dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
+{
+ return -EPERM;
+}
+
+static void secure_heap_free(struct dma_buf *dmabuf)
+{
+ struct secure_buffer *sec_buf = dmabuf->priv;
+ struct secure_heap *sec_heap = dma_heap_get_drvdata(sec_buf->heap);
+
+ secure_heap_secure_memory_free(sec_heap, sec_buf);
+ kfree(sec_buf);
+}
+
+static const struct dma_buf_ops sec_heap_buf_ops = {
+ .attach = secure_heap_attach,
+ .detach = secure_heap_detach,
+ .map_dma_buf = secure_heap_map_dma_buf,
+ .unmap_dma_buf = secure_heap_unmap_dma_buf,
+ .begin_cpu_access = secure_heap_dma_buf_begin_cpu_access,
+ .end_cpu_access = secure_heap_dma_buf_end_cpu_access,
+ .mmap = secure_heap_dma_buf_mmap,
+ .release = secure_heap_free,
+};
+
static struct dma_buf *
secure_heap_allocate(struct dma_heap *heap, unsigned long size,
unsigned long fd_flags, unsigned long heap_flags)
@@ -271,6 +390,7 @@ secure_heap_allocate(struct dma_heap *heap, unsigned long size,
if (ret)
goto err_free_buf;
exp_info.exp_name = dma_heap_get_name(heap);
+ exp_info.ops = &sec_heap_buf_ops;
exp_info.size = sec_buf->size;
exp_info.flags = fd_flags;
exp_info.priv = sec_buf;
--
2.25.1