[PATCH v9 5/9] tee: new ioctl to a register tee_shm from a dmabuf file descriptor
Jens Wiklander
jens.wiklander at linaro.org
Mon May 26 01:34:19 PDT 2025
On Fri, May 23, 2025 at 3:31 PM Sumit Garg <sumit.garg at kernel.org> wrote:
>
> On Tue, May 20, 2025 at 05:16:48PM +0200, Jens Wiklander wrote:
> > From: Etienne Carriere <etienne.carriere at foss.st.com>
> >
> > Add a userspace API 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 returned file descriptor.
> >
> > Userspace is free to close the dmabuf file descriptor after it has been
> > registered since all the resources are now held via the new tee_shm
> > object.
> >
> > Closing the tee_shm file descriptor will eventually release all
> > resources used by the tee_shm object when all references are released.
> >
> > The new IOCTL, TEE_IOC_SHM_REGISTER_FD, supports dmabuf references to
> > physically contiguous memory buffers. Dmabuf references acquired from
> > the TEE DMA-heap can be used as protected memory for Secure Video Path
> > and such use cases. It depends on the TEE and the TEE driver if dmabuf
> > references acquired by other means can be used.
> >
> > A new tee_shm flag is added to identify tee_shm objects built from a
> > registered dmabuf, TEE_SHM_DMA_BUF.
> >
> > Signed-off-by: Etienne Carriere <etienne.carriere at foss.st.com>
> > Signed-off-by: Olivier Masse <olivier.masse at nxp.com>
> > Signed-off-by: Jens Wiklander <jens.wiklander at linaro.org>
> > ---
> > drivers/tee/tee_core.c | 63 +++++++++++++++++++++-
> > drivers/tee/tee_private.h | 10 ++++
> > drivers/tee/tee_shm.c | 111 ++++++++++++++++++++++++++++++++++++--
> > include/linux/tee_core.h | 1 +
> > include/linux/tee_drv.h | 10 ++++
> > include/uapi/linux/tee.h | 31 +++++++++++
> > 6 files changed, 221 insertions(+), 5 deletions(-)
>
> With below minor comments fixed, feel free to add:
>
> Reviewed-by: Sumit Garg <sumit.garg at oss.qualcomm.com>
>
> >
> > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> > index 5259b8223c27..0e9d9e5872a4 100644
> > --- a/drivers/tee/tee_core.c
> > +++ b/drivers/tee/tee_core.c
> > @@ -353,11 +353,49 @@ 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,
> > @@ -388,6 +426,26 @@ static int param_from_user_memref(struct tee_context *ctx,
> > tee_shm_put(shm);
> > return -EINVAL;
> > }
> > +
> > + 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 are clear of 0.
> > + * We're getting another reference since
> > + * this shm will be used in the parameter
> > + * list instead of the shm we got with
> > + * tee_shm_get_from_id() above.
> > + */
> > + refcount_inc(&ref->parent_shm->refcount);
> > + tee_shm_put(shm);
> > + shm = ref->parent_shm;
> > + offs = ref->offset;
> > + }
> > + }
> > } else if (ctx->cap_memref_null) {
> > /* Pass NULL pointer to OP-TEE */
> > shm = NULL;
> > @@ -395,7 +453,7 @@ static int param_from_user_memref(struct tee_context *ctx,
> > return -EINVAL;
> > }
> >
> > - memref->shm_offs = ip->a;
> > + memref->shm_offs = ip->a + offs;
>
> Is this an issue being detected now? If yes then shouldn't it be a
> separate fix eligible for backport?
No, this is to add an eventual offset for a TEE_SHM_DMA_BUF, introduced above.
>
> > memref->size = ip->b;
> > memref->shm = shm;
> >
> > @@ -841,6 +899,8 @@ 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:
> > @@ -1300,3 +1360,4 @@ 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..308467705da6 100644
> > --- a/drivers/tee/tee_private.h
> > +++ b/drivers/tee/tee_private.h
> > @@ -13,6 +13,16 @@
> > #include <linux/mutex.h>
> > #include <linux/types.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;
> > +};
> > +
> > int tee_shm_get_fd(struct tee_shm *shm);
> >
> > bool tee_device_get(struct tee_device *teedev);
> > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> > index daf6e5cfd59a..e1ed52ee0a16 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>
> > @@ -45,7 +46,23 @@ 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 +74,10 @@ 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);
>
> redundant change?
Yes, I'll remove it.
>
> >
> > - kfree(shm);
> > + kfree(p);
> >
> > tee_device_put(teedev);
> > }
> > @@ -169,7 +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)
> > {
> > @@ -179,6 +197,91 @@ 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 = -EINVAL;
> > + 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);
> > +
> > /**
> > * 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 b8b99c97e00c..02c07f661349 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..8ec5f46fbfbe 100644
> > --- a/include/uapi/linux/tee.h
> > +++ b/include/uapi/linux/tee.h
> > @@ -118,6 +118,37 @@ 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 dmabuf reference
> > + * @size: [out] Size of referenced memory
> > + * @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 the
> > + * kernel. The supplied file deccriptor can be closed if it's not needed
> > + * for other purposes. 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)
>
> Please add this IOCTL in correct sequence order.
OK, I'll fix it.
Thanks,
Jens
>
> -Sumit
>
> > +
> > /**
> > * struct tee_ioctl_buf_data - Variable sized buffer
> > * @buf_ptr: [in] A __user pointer to a buffer
> > --
> > 2.43.0
> >
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