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

[Olivier Masse]

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@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>
> Signed-off-by: Olivier Masse <olivier.masse@xxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> 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