[PATCH v6 06/10] tee: new ioctl to a register tee_shm from a dmabuf file descriptor

Jens Wiklander
2025-03-05T13:06:58Z

From: Etienne Carriere <etienne.carriere@linaro.org>

Enable userspace to create a tee_shm object that refers to a dmabuf
reference.

Userspace registers the dmabuf file descriptor as in a tee_shm object.
The registration is completed with a tee_shm file descriptor returned to
userspace.

Userspace is free to close the dmabuf file descriptor now since all the
resources are now held via the tee_shm object.

Closing the tee_shm file descriptor will release all resources used by the
tee_shm object.

This change only support dmabuf references that relates to physically
contiguous memory buffers.

New tee_shm flag to identify tee_shm objects built from a registered
dmabuf, TEE_SHM_DMA_BUF.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Olivier Masse <olivier.masse@nxp.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
---
drivers/tee/tee_core.c | 145 ++++++++++++++++++++++++++-----------
drivers/tee/tee_private.h | 1 +
drivers/tee/tee_shm.c | 146 ++++++++++++++++++++++++++++++++++++--
include/linux/tee_core.h | 1 +
include/linux/tee_drv.h | 10 +++
include/uapi/linux/tee.h | 29 ++++++++
6 files changed, 288 insertions(+), 44 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 685afcaa3ea1..3a71643766d5 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -353,6 +353,103 @@ tee_ioctl_shm_register(struct tee_context *ctx,
return ret;
}

+static int
+tee_ioctl_shm_register_fd(struct tee_context *ctx,
+ struct tee_ioctl_shm_register_fd_data __user *udata)
+{
+ struct tee_ioctl_shm_register_fd_data data;
+ struct tee_shm *shm;
+ long ret;
+
+ if (copy_from_user(&data, udata, sizeof(data)))
+ return -EFAULT;
+
+ /* Currently no input flags are supported */
+ if (data.flags)
+ return -EINVAL;
+
+ shm = tee_shm_register_fd(ctx, data.fd);
+ if (IS_ERR(shm))
+ return -EINVAL;
+
+ data.id = shm->id;
+ data.flags = shm->flags;
+ data.size = shm->size;
+
+ if (copy_to_user(udata, &data, sizeof(data)))
+ ret = -EFAULT;
+ else
+ ret = tee_shm_get_fd(shm);
+
+ /*
+ * When user space closes the file descriptor the shared memory
+ * should be freed or if tee_shm_get_fd() failed then it will
+ * be freed immediately.
+ */
+ tee_shm_put(shm);
+ return ret;
+}
+
+static int param_from_user_memref(struct tee_context *ctx,
+ struct tee_param_memref *memref,
+ struct tee_ioctl_param *ip)
+{
+ struct tee_shm *shm;
+ size_t offs = 0;
+
+ /*
+ * If a NULL pointer is passed to a TA in the TEE,
+ * the ip.c IOCTL parameters is set to TEE_MEMREF_NULL
+ * indicating a NULL memory reference.
+ */
+ if (ip->c != TEE_MEMREF_NULL) {
+ /*
+ * If we fail to get a pointer to a shared
+ * memory object (and increase the ref count)
+ * from an identifier we return an error. All
+ * pointers that has been added in params have
+ * an increased ref count. It's the callers
+ * responibility to do tee_shm_put() on all
+ * resolved pointers.
+ */
+ shm = tee_shm_get_from_id(ctx, ip->c);
+ if (IS_ERR(shm))
+ return PTR_ERR(shm);
+
+ /*
+ * Ensure offset + size does not overflow
+ * offset and does not overflow the size of
+ * the referred shared memory object.
+ */
+ if ((ip->a + ip->b) < ip->a ||
+ (ip->a + ip->b) > shm->size) {
+ tee_shm_put(shm);
+ return -EINVAL;
+ }
+
+ if (shm->flags & TEE_SHM_DMA_BUF) {
+ struct tee_shm *parent_shm;
+
+ parent_shm = tee_shm_get_parent_shm(shm, &offs);
+ if (parent_shm) {
+ tee_shm_put(shm);
+ shm = parent_shm;
+ }
+ }
+ } else if (ctx->cap_memref_null) {
+ /* Pass NULL pointer to OP-TEE */
+ shm = NULL;
+ } else {
+ return -EINVAL;
+ }
+
+ memref->shm_offs = ip->a + offs;
+ memref->size = ip->b;
+ memref->shm = shm;
+
+ return 0;
+}
+
static int params_from_user(struct tee_context *ctx, struct tee_param *params,
size_t num_params,
struct tee_ioctl_param __user *uparams)
@@ -360,8 +457,8 @@ static int params_from_user(struct tee_context *ctx, struct tee_param *params,
size_t n;

for (n = 0; n < num_params; n++) {
- struct tee_shm *shm;
struct tee_ioctl_param ip;
+ int rc;

if (copy_from_user(&ip, uparams + n, sizeof(ip)))
return -EFAULT;
@@ -384,45 +481,10 @@ static int params_from_user(struct tee_context *ctx, struct tee_param *params,
case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT:
case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
- /*
- * If a NULL pointer is passed to a TA in the TEE,
- * the ip.c IOCTL parameters is set to TEE_MEMREF_NULL
- * indicating a NULL memory reference.
- */
- if (ip.c != TEE_MEMREF_NULL) {
- /*
- * If we fail to get a pointer to a shared
- * memory object (and increase the ref count)
- * from an identifier we return an error. All
- * pointers that has been added in params have
- * an increased ref count. It's the callers
- * responibility to do tee_shm_put() on all
- * resolved pointers.
- */
- shm = tee_shm_get_from_id(ctx, ip.c);
- if (IS_ERR(shm))
- return PTR_ERR(shm);
-
- /*
- * Ensure offset + size does not overflow
- * offset and does not overflow the size of
- * the referred shared memory object.
- */
- if ((ip.a + ip.b) < ip.a ||
- (ip.a + ip.b) > shm->size) {
- tee_shm_put(shm);
- return -EINVAL;
- }
- } else if (ctx->cap_memref_null) {
- /* Pass NULL pointer to OP-TEE */
- shm = NULL;
- } else {
- return -EINVAL;
- }
-
- params[n].u.memref.shm_offs = ip.a;
- params[n].u.memref.size = ip.b;
- params[n].u.memref.shm = shm;
+ rc = param_from_user_memref(ctx, &params[n].u.memref,
+ &ip);
+ if (rc)
+ return rc;
break;
default:
/* Unknown attribute */
@@ -827,6 +889,8 @@ static long tee_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return tee_ioctl_shm_alloc(ctx, uarg);
case TEE_IOC_SHM_REGISTER:
return tee_ioctl_shm_register(ctx, uarg);
+ case TEE_IOC_SHM_REGISTER_FD:
+ return tee_ioctl_shm_register_fd(ctx, uarg);
case TEE_IOC_OPEN_SESSION:
return tee_ioctl_open_session(ctx, uarg);
case TEE_IOC_INVOKE:
@@ -1288,3 +1352,4 @@ MODULE_AUTHOR("Linaro");
MODULE_DESCRIPTION("TEE Driver");
MODULE_VERSION("1.0");
MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("DMA_BUF");
diff --git a/drivers/tee/tee_private.h b/drivers/tee/tee_private.h
index 6c6ff5d5eed2..aad7f6c7e0f0 100644
--- a/drivers/tee/tee_private.h
+++ b/drivers/tee/tee_private.h
@@ -24,6 +24,7 @@ void teedev_ctx_put(struct tee_context *ctx);
struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size);
struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
unsigned long addr, size_t length);
+struct tee_shm *tee_shm_get_parent_shm(struct tee_shm *shm, size_t *offs);

int tee_heap_update_from_dma_buf(struct tee_device *teedev,
struct dma_buf *dmabuf, size_t *offset,
diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index daf6e5cfd59a..8b79918468b5 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -4,6 +4,7 @@
*/
#include <linux/anon_inodes.h>
#include <linux/device.h>
+#include <linux/dma-buf.h>
#include <linux/idr.h>
#include <linux/io.h>
#include <linux/mm.h>
@@ -15,6 +16,16 @@
#include <linux/highmem.h>
#include "tee_private.h"

+/* extra references appended to shm object for registered shared memory */
+struct tee_shm_dmabuf_ref {
+ struct tee_shm shm;
+ size_t offset;
+ struct dma_buf *dmabuf;
+ struct dma_buf_attachment *attach;
+ struct sg_table *sgt;
+ struct tee_shm *parent_shm;
+};
+
static void shm_put_kernel_pages(struct page **pages, size_t page_count)
{
size_t n;
@@ -45,7 +56,23 @@ static void release_registered_pages(struct tee_shm *shm)

static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
{
- if (shm->flags & TEE_SHM_POOL) {
+ struct tee_shm *parent_shm = NULL;
+ void *p = shm;
+
+ if (shm->flags & TEE_SHM_DMA_BUF) {
+ struct tee_shm_dmabuf_ref *ref;
+
+ ref = container_of(shm, struct tee_shm_dmabuf_ref, shm);
+ parent_shm = ref->parent_shm;
+ p = ref;
+ if (ref->attach) {
+ dma_buf_unmap_attachment(ref->attach, ref->sgt,
+ DMA_BIDIRECTIONAL);
+
+ dma_buf_detach(ref->dmabuf, ref->attach);
+ }
+ dma_buf_put(ref->dmabuf);
+ } else if (shm->flags & TEE_SHM_POOL) {
teedev->pool->ops->free(teedev->pool, shm);
} else if (shm->flags & TEE_SHM_DYNAMIC) {
int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
@@ -57,9 +84,10 @@ static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
release_registered_pages(shm);
}

- teedev_ctx_put(shm->ctx);
+ if (shm->ctx)
+ teedev_ctx_put(shm->ctx);

- kfree(shm);
+ kfree(p);

tee_device_put(teedev);
}
@@ -169,7 +197,7 @@ struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size)
* tee_client_invoke_func(). The memory allocated is later freed with a
* call to tee_shm_free().
*
- * @returns a pointer to 'struct tee_shm'
+ * @returns a pointer to 'struct tee_shm' on success, and ERR_PTR on failure
*/
struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size)
{
@@ -179,6 +207,116 @@ struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size)
}
EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf);

+struct tee_shm *tee_shm_register_fd(struct tee_context *ctx, int fd)
+{
+ struct tee_shm_dmabuf_ref *ref;
+ int rc;
+
+ if (!tee_device_get(ctx->teedev))
+ return ERR_PTR(-EINVAL);
+
+ teedev_ctx_get(ctx);
+
+ ref = kzalloc(sizeof(*ref), GFP_KERNEL);
+ if (!ref) {
+ rc = -ENOMEM;
+ goto err_put_tee;
+ }
+
+ refcount_set(&ref->shm.refcount, 1);
+ ref->shm.ctx = ctx;
+ ref->shm.id = -1;
+ ref->shm.flags = TEE_SHM_DMA_BUF;
+
+ ref->dmabuf = dma_buf_get(fd);
+ if (IS_ERR(ref->dmabuf)) {
+ rc = PTR_ERR(ref->dmabuf);
+ goto err_kfree_ref;
+ }
+
+ rc = tee_heap_update_from_dma_buf(ctx->teedev, ref->dmabuf,
+ &ref->offset, &ref->shm,
+ &ref->parent_shm);
+ if (!rc)
+ goto out;
+ if (rc != -EINVAL)
+ goto err_put_dmabuf;
+
+ ref->attach = dma_buf_attach(ref->dmabuf, &ctx->teedev->dev);
+ if (IS_ERR(ref->attach)) {
+ rc = PTR_ERR(ref->attach);
+ goto err_put_dmabuf;
+ }
+
+ ref->sgt = dma_buf_map_attachment(ref->attach, DMA_BIDIRECTIONAL);
+ if (IS_ERR(ref->sgt)) {
+ rc = PTR_ERR(ref->sgt);
+ goto err_detach;
+ }
+
+ if (sg_nents(ref->sgt->sgl) != 1) {
+ rc = PTR_ERR(ref->sgt->sgl);
+ goto err_unmap_attachement;
+ }
+
+ ref->shm.paddr = page_to_phys(sg_page(ref->sgt->sgl));
+ ref->shm.size = ref->sgt->sgl->length;
+
+out:
+ mutex_lock(&ref->shm.ctx->teedev->mutex);
+ ref->shm.id = idr_alloc(&ref->shm.ctx->teedev->idr, &ref->shm,
+ 1, 0, GFP_KERNEL);
+ mutex_unlock(&ref->shm.ctx->teedev->mutex);
+ if (ref->shm.id < 0) {
+ rc = ref->shm.id;
+ if (ref->attach)
+ goto err_unmap_attachement;
+ goto err_put_dmabuf;
+ }
+
+ return &ref->shm;
+
+err_unmap_attachement:
+ dma_buf_unmap_attachment(ref->attach, ref->sgt, DMA_BIDIRECTIONAL);
+err_detach:
+ dma_buf_detach(ref->dmabuf, ref->attach);
+err_put_dmabuf:
+ dma_buf_put(ref->dmabuf);
+err_kfree_ref:
+ kfree(ref);
+err_put_tee:
+ teedev_ctx_put(ctx);
+ tee_device_put(ctx->teedev);
+
+ return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_GPL(tee_shm_register_fd);
+
+struct tee_shm *tee_shm_get_parent_shm(struct tee_shm *shm, size_t *offs)
+{
+ struct tee_shm *parent_shm = NULL;
+
+ if (shm->flags & TEE_SHM_DMA_BUF) {
+ struct tee_shm_dmabuf_ref *ref;
+
+ ref = container_of(shm, struct tee_shm_dmabuf_ref, shm);
+ if (ref->parent_shm) {
+ /*
+ * the shm already has one reference to
+ * ref->parent_shm so we should be clear of 0.
+ * We're getting another reference since the caller
+ * of this function expects to put the returned
+ * parent_shm when it's done with it.
+ */
+ parent_shm = ref->parent_shm;
+ refcount_inc(&parent_shm->refcount);
+ *offs = ref->offset;
+ }
+ }
+
+ return parent_shm;
+}
+
/**
* tee_shm_alloc_priv_buf() - Allocate shared memory for a privately shared
* kernel buffer
diff --git a/include/linux/tee_core.h b/include/linux/tee_core.h
index 16ef078247ae..6bd833b6d0e1 100644
--- a/include/linux/tee_core.h
+++ b/include/linux/tee_core.h
@@ -28,6 +28,7 @@
#define TEE_SHM_USER_MAPPED BIT(1) /* Memory mapped in user space */
#define TEE_SHM_POOL BIT(2) /* Memory allocated from pool */
#define TEE_SHM_PRIV BIT(3) /* Memory private to TEE driver */
+#define TEE_SHM_DMA_BUF BIT(4) /* Memory with dma-buf handle */

#define TEE_DEVICE_FLAG_REGISTERED 0x1
#define TEE_MAX_DEV_NAME_LEN 32
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index a54c203000ed..824f1251de60 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -116,6 +116,16 @@ struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
void *addr, size_t length);

+/**
+ * tee_shm_register_fd() - Register shared memory from file descriptor
+ *
+ * @ctx: Context that allocates the shared memory
+ * @fd: Shared memory file descriptor reference
+ *
+ * @returns a pointer to 'struct tee_shm' on success, and ERR_PTR on failure
+ */
+struct tee_shm *tee_shm_register_fd(struct tee_context *ctx, int fd);
+
/**
* tee_shm_free() - Free shared memory
* @shm: Handle to shared memory to free
diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
index d0430bee8292..1f9a4ac2b211 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -118,6 +118,35 @@ struct tee_ioctl_shm_alloc_data {
#define TEE_IOC_SHM_ALLOC _IOWR(TEE_IOC_MAGIC, TEE_IOC_BASE + 1, \
struct tee_ioctl_shm_alloc_data)

+/**
+ * struct tee_ioctl_shm_register_fd_data - Shared memory registering argument
+ * @fd: [in] File descriptor identifying the shared memory
+ * @size: [out] Size of shared memory to allocate
+ * @flags: [in] Flags to/from allocation.
+ * @id: [out] Identifier of the shared memory
+ *
+ * The flags field should currently be zero as input. Updated by the call
+ * with actual flags as defined by TEE_IOCTL_SHM_* above.
+ * This structure is used as argument for TEE_IOC_SHM_REGISTER_FD below.
+ */
+struct tee_ioctl_shm_register_fd_data {
+ __s64 fd;
+ __u64 size;
+ __u32 flags;
+ __s32 id;
+};
+
+/**
+ * TEE_IOC_SHM_REGISTER_FD - register a shared memory from a file descriptor
+ *
+ * Returns a file descriptor on success or < 0 on failure
+ *
+ * The returned file descriptor refers to the shared memory object in kernel
+ * land. The shared memory is freed when the descriptor is closed.
+ */
+#define TEE_IOC_SHM_REGISTER_FD _IOWR(TEE_IOC_MAGIC, TEE_IOC_BASE + 8, \
+ struct tee_ioctl_shm_register_fd_data)
+
/**
* struct tee_ioctl_buf_data - Variable sized buffer
* @buf_ptr: [in] A __user pointer to a buffer
--
2.43.0