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

Hi Sumit,

On Tue, Mar 25, 2025 at 7:50 AM Sumit Garg sumit.garg@kernel.org wrote:

Hi Jens,

On Wed, Mar 05, 2025 at 02:04:12PM +0100, Jens Wiklander wrote:

...

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(-)

I am still trying to find if we really need a separate IOCTL to register DMA heap with TEE subsystem. Can't we initialize tee_shm as a member of struct tee_heap_buffer in tee_dma_heap_alloc() where the allocation happens?

No, that's not possible since we don't have a tee_context availble so we can't assign an ID that userspace can use for this shm object.

We could add new attribute types TEE_IOCTL_PARAM_ATTR_TYPE_MEMFD_*, but it's a bit more complicated than that since we'd also need to update for the life cycle.

We can always find a reference back to tee_shm object from DMA buffer.

Yes

Cheers, Jens

-Sumit

...

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