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

Hi Sumit,

Thanks for your comments, please find my answer below.

On ven., 2022-08-12 at 19:36 +0530, Sumit Garg wrote:

Caution: EXT Email

Hi Olivier,

On Thu, 11 Aug 2022 at 19:26, Olivier Masse olivier.masse@nxp.com 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.

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.

But it will need more logic in OPTEE OS to verify that all pages are in the Secure Data Path protected area. Our solution use a fixed protected reserved memory region and do not rely on a dynamic protection set in secure.

Best regards, Olivier

-Sumit

...

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 From: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com... (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..6f84060ad005 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;
  

+} __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

-- 2.25.0