Re: [PATCH v2 1/1] tee: new ioctl to a register tee_shm from a dmabuf file descriptor

Hi Joakim, Hi Etienne,

Let me bring back this pull request for OPTEE Linux driver.

Last feedback was from Christian König and Sumit Garg. From Christian:

Just two comments:

1. Dmitry is working on a change which renames some functions and

makes it mandatory to call them with the dma_resv lock held.

Depending on how you want to upstream this change you will certainly run into conflicts with that.

Is there any update on these changes ?

2. Would it be possible to do this dynamically? In other words does

the tee driver has a concept of buffers moving around?

We do not support dynamic secure memory heap.

From Sumit:

What limits you to extend this feature to non-contiguous memory buffers? I believe that should be possible with OP-TEE dynamic shared memory which gives you the granularity to register a list of pages.

Our solution use a fixed protected reserved memory region and do not rely on a dynamic protection managed in secure.

The scope of this implementation rely on a static memory region handled by a specific DMA Heap type.

Best regards, Olivier MASSE

On ven., 2022-08-12 at 16:30 +0200, Olivier Masse wrote:

From: Etienne Carriere etienne.carriere@linaro.org

This change allows userland to create a tee_shm object that refers to a dmabuf reference.

Userland provides a dmabuf file descriptor as buffer reference. The created tee_shm object exported as a brand new dmabuf reference used to provide a clean fd to userland. Userland shall closed this new fd to release the tee_shm object resources. The initial dmabuf resources are tracked independently through original dmabuf file descriptor.

Once the buffer is registered and until it is released, TEE driver keeps a refcount on the registered dmabuf structure.

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_EXT_DMA_BUF. Such tee_shm structures are flagged with TEE_SHM_EXT_DMA_BUF.

Co-Developed-by: Etienne Carriere etienne.carriere@linaro.org Signed-off-by: Olivier Masse olivier.masse@nxp.com Reported-by: kernel test robot lkp@intel.com From: https://github.com/linaro-swg/linux.git (cherry picked from commit 41e21e5c405530590dc2dd10b2a8dbe64589840f)

---

drivers/tee/tee_core.c | 38 +++++++++++++++ drivers/tee/tee_shm.c | 99 +++++++++++++++++++++++++++++++++++++++- include/linux/tee_drv.h | 11 +++++ include/uapi/linux/tee.h | 29 ++++++++++++ 4 files changed, 175 insertions(+), 2 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 8aa1a4836b92..7c45cbf85eb9 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -355,6 +355,42 @@ 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 params_from_user(struct tee_context *ctx, struct tee_param *params, size_t num_params, struct tee_ioctl_param __user *uparams) @@ -829,6 +865,8 @@ 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:

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index 836872467dc6..55a3fbbb022e 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/mm.h> #include <linux/sched.h> @@ -12,6 +13,14 @@ #include <linux/uio.h> #include "tee_private.h" +/* extra references appended to shm object for registered shared memory */ +struct tee_shm_dmabuf_ref {

• struct tee_shm shm;
  

• struct dma_buf *dmabuf;
  

• struct dma_buf_attachment *attach;
  

• struct sg_table *sgt;
  

+};

static void shm_put_kernel_pages(struct page **pages, size_t page_count) { size_t n; @@ -71,7 +80,16 @@ 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) {

• if (shm->flags & TEE_SHM_EXT_DMA_BUF) {

• struct tee_shm_dmabuf_ref *ref;
  

• ref = container_of(shm, struct tee_shm_dmabuf_ref,
  

shm);

• 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); @@ -195,7 +213,7 @@ 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) { @@ -229,6 +247,83 @@ struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size) } EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_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->dmabuf = dma_buf_get(fd);
• if (IS_ERR(ref->dmabuf)) {

• rc = PTR_ERR(ref->dmabuf);
  

• goto err_put_dmabuf;
  

• }
• ref->attach = dma_buf_attach(ref->dmabuf, &ref->shm.ctx-

...

teedev->dev);

• if (IS_ERR(ref->attach)) {

• rc = PTR_ERR(ref->attach);
  

• goto err_detach;
  

• }
• ref->sgt = dma_buf_map_attachment(ref->attach,

DMA_BIDIRECTIONAL);

• if (IS_ERR(ref->sgt)) {

• rc = PTR_ERR(ref->sgt);
  

• goto err_unmap_attachement;
  

• }
• if (sg_nents(ref->sgt->sgl) != 1) {

• rc = PTR_ERR(ref->sgt->sgl);
  

• goto err_unmap_attachement;
  

• }
• ref->shm.paddr = sg_dma_address(ref->sgt->sgl);
• ref->shm.size = sg_dma_len(ref->sgt->sgl);
• ref->shm.flags = TEE_SHM_EXT_DMA_BUF;
• 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;
  

• goto err_idr_remove;
  

• }
• return &ref->shm;

+err_idr_remove:

• mutex_lock(&ctx->teedev->mutex);
• idr_remove(&ctx->teedev->idr, ref->shm.id);
• mutex_unlock(&ctx->teedev->mutex);

+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);
• 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);

static struct tee_shm * register_shm_helper(struct tee_context *ctx, unsigned long addr, size_t length, u32 flags, int id) diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h index 911cad324acc..40ddd5376c2d 100644 --- a/include/linux/tee_drv.h +++ b/include/linux/tee_drv.h @@ -25,6 +25,7 @@ #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_EXT_DMA_BUF BIT(4) /* Memory with dma-buf handle */ struct device; struct tee_device; @@ -276,6 +277,16 @@ 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_is_dynamic() - Check if shared memory object is of the

dynamic kind

• @shm: Shared memory handle

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 25a6c534beb1..baf3cd7cfdac 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -121,6 +121,35 @@ 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;

+} __attribute__ ((aligned (8)));

+/**

• • 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