Re: [RFC PATCH 2/4] tee: new ioctl to a register tee_shm from a dmabuf file descriptor

On Fri, Aug 30, 2024 at 12:04 AM Jens Wiklander jens.wiklander@linaro.org 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 | 38 ++++++++++++++ drivers/tee/tee_shm.c | 104 +++++++++++++++++++++++++++++++++++++-- include/linux/tee_drv.h | 11 +++++ include/uapi/linux/tee.h | 29 +++++++++++ 4 files changed, 179 insertions(+), 3 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index e59c20d74b36..3dfd5428d58c 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -356,6 +356,42 @@ 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) @@ -830,6 +866,8 @@ 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 731d9028b67f..a1cb3c8b6423 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> @@ -14,6 +15,14 @@ #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;
  

•   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; @@ -44,7 +53,16 @@ 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_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);
  

@@ -56,7 +74,8 @@ 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);
  
  

@@ -168,7 +187,7 @@ 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) { @@ -178,6 +197,85 @@ 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->dmabuf = dma_buf_get(fd);
  

•   if (IS_ERR(ref->dmabuf)) {
  

•           rc = PTR_ERR(ref->dmabuf);
  

•           goto err_put_dmabuf;
  

•   }
  

Hi,

Most of the gotos in the errors paths from here on look offset by one to me. Attempting to put a dmabuf after failing to get, detaching after failing to attach, unmapping after failing to map, removing an IDR after failing to allocate one.

•   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 = page_to_phys(sg_page(ref->sgt->sgl));
  

•   ref->shm.size = ref->sgt->sgl->length;
  

•   ref->shm.flags = TEE_SHM_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);

/**

• tee_shm_alloc_priv_buf() - Allocate shared memory for a privately shared

•                       kernel buffer
  

diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h index 71632e3c5f18..6a1fee689007 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_DMA_BUF BIT(4) /* Memory with dma-buf handle */

struct device; struct tee_device; @@ -275,6 +276,16 @@ void *tee_get_drvdata(struct tee_device *teedev); struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size); struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);

+/**

• • 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);

struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx, void *addr, size_t length);

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 23e57164693c..77bc8ef24d3c 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -117,6 +117,35 @@ 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

-- 2.34.1