Date:   Fri, 12 Aug 2022 14:23:57 +0000
From:   Olivier Masse <olivier.masse@....com>
To:     "sumit.garg@...aro.org" <sumit.garg@...aro.org>
CC:     "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
        "christian.koenig@....com" <christian.koenig@....com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        Clément Faure <clement.faure@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "jens.wiklander@...aro.org" <jens.wiklander@...aro.org>,
        "op-tee@...ts.trustedfirmware.org" <op-tee@...ts.trustedfirmware.org>
Subject: 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@....com>
> wrote:
> > 
> > From: Etienne Carriere <etienne.carriere@...aro.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@...aro.org>
> > Signed-off-by: Olivier Masse <olivier.masse@....com>
> > From: 
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Flinaro-swg%2Flinux.git&amp;data=05%7C01%7Colivier.masse%40nxp.com%7C204e0821d1c84355ed4208da7c6be5c6%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637959100100176447%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=MRfnQNbwAIj%2Bnd9tSjSb5Nzrv3sQVpVMIdOxxRfu6U4%3D&amp;reserved=0
> > (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
> > 

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