Re: [PATCH v6 03/10] optee: account for direction while converting parameters

[Sumit Garg <sumit.garg@kernel.org>]

Hi Jens,

On Mon, Mar 17, 2025 at 08:42:01AM +0100, Jens Wiklander wrote:
> Hi Sumit,
> 
> On Thu, Mar 13, 2025 at 11:41 AM Sumit Garg <sumit.garg@kernel.org> wrote:
> >
> > Hi Jens,
> >
> > On Wed, Mar 05, 2025 at 02:04:09PM +0100, Jens Wiklander wrote:
> > > The OP-TEE backend driver has two internal function pointers to convert
> > > between the subsystem type struct tee_param and the OP-TEE type struct
> > > optee_msg_param.
> > >
> > > The conversion is done from one of the types to the other, which is then
> > > involved in some operation and finally converted back to the original
> > > type. When converting to prepare the parameters for the operation, all
> > > fields must be taken into account, but then converting back, it's enough
> > > to update only out-values and out-sizes. So, an update_out parameter is
> > > added to the conversion functions to tell if all or only some fields
> > > must be copied.
> > >
> > > This is needed in a later patch where it might get confusing when
> > > converting back in from_msg_param() callback since an allocated
> > > restricted SHM can be using the sec_world_id of the used restricted
> > > memory pool and that doesn't translate back well.
> > >
> > > Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
> > > ---
> > >  drivers/tee/optee/call.c          | 10 ++--
> > >  drivers/tee/optee/ffa_abi.c       | 43 +++++++++++++----
> > >  drivers/tee/optee/optee_private.h | 42 +++++++++++------
> > >  drivers/tee/optee/rpc.c           | 31 +++++++++----
> > >  drivers/tee/optee/smc_abi.c       | 76 +++++++++++++++++++++++--------
> > >  5 files changed, 144 insertions(+), 58 deletions(-)
> > >
> > > diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
> > > index 16eb953e14bb..f1533b894726 100644
> > > --- a/drivers/tee/optee/call.c
> > > +++ b/drivers/tee/optee/call.c
> > > @@ -400,7 +400,8 @@ int optee_open_session(struct tee_context *ctx,
> > >       export_uuid(msg_arg->params[1].u.octets, &client_uuid);
> > >
> > >       rc = optee->ops->to_msg_param(optee, msg_arg->params + 2,
> > > -                                   arg->num_params, param);
> > > +                                   arg->num_params, param,
> > > +                                   false /*!update_out*/);
> > >       if (rc)
> > >               goto out;
> > >
> > > @@ -427,7 +428,8 @@ int optee_open_session(struct tee_context *ctx,
> > >       }
> > >
> > >       if (optee->ops->from_msg_param(optee, param, arg->num_params,
> > > -                                    msg_arg->params + 2)) {
> > > +                                    msg_arg->params + 2,
> > > +                                    true /*update_out*/)) {
> > >               arg->ret = TEEC_ERROR_COMMUNICATION;
> > >               arg->ret_origin = TEEC_ORIGIN_COMMS;
> > >               /* Close session again to avoid leakage */
> > > @@ -541,7 +543,7 @@ int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
> > >       msg_arg->cancel_id = arg->cancel_id;
> > >
> > >       rc = optee->ops->to_msg_param(optee, msg_arg->params, arg->num_params,
> > > -                                   param);
> > > +                                   param, false /*!update_out*/);
> > >       if (rc)
> > >               goto out;
> > >
> > > @@ -551,7 +553,7 @@ int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
> > >       }
> > >
> > >       if (optee->ops->from_msg_param(optee, param, arg->num_params,
> > > -                                    msg_arg->params)) {
> > > +                                    msg_arg->params, true /*update_out*/)) {
> > >               msg_arg->ret = TEEC_ERROR_COMMUNICATION;
> > >               msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
> > >       }
> > > diff --git a/drivers/tee/optee/ffa_abi.c b/drivers/tee/optee/ffa_abi.c
> > > index 4ca1d5161b82..e4b08cd195f3 100644
> > > --- a/drivers/tee/optee/ffa_abi.c
> > > +++ b/drivers/tee/optee/ffa_abi.c
> > > @@ -122,15 +122,21 @@ static int optee_shm_rem_ffa_handle(struct optee *optee, u64 global_id)
> > >   */
> > >
> > >  static void from_msg_param_ffa_mem(struct optee *optee, struct tee_param *p,
> > > -                                u32 attr, const struct optee_msg_param *mp)
> > > +                                u32 attr, const struct optee_msg_param *mp,
> > > +                                bool update_out)
> > >  {
> > >       struct tee_shm *shm = NULL;
> > >       u64 offs_high = 0;
> > >       u64 offs_low = 0;
> > >
> > > +     if (update_out) {
> > > +             if (attr == OPTEE_MSG_ATTR_TYPE_FMEM_INPUT)
> > > +                     return;
> > > +             goto out;
> > > +     }
> > > +
> > >       p->attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT +
> > >                 attr - OPTEE_MSG_ATTR_TYPE_FMEM_INPUT;
> > > -     p->u.memref.size = mp->u.fmem.size;
> > >
> > >       if (mp->u.fmem.global_id != OPTEE_MSG_FMEM_INVALID_GLOBAL_ID)
> > >               shm = optee_shm_from_ffa_handle(optee, mp->u.fmem.global_id);
> > > @@ -141,6 +147,8 @@ static void from_msg_param_ffa_mem(struct optee *optee, struct tee_param *p,
> > >               offs_high = mp->u.fmem.offs_high;
> > >       }
> > >       p->u.memref.shm_offs = offs_low | offs_high << 32;
> > > +out:
> > > +     p->u.memref.size = mp->u.fmem.size;
> > >  }
> > >
> > >  /**
> > > @@ -150,12 +158,14 @@ static void from_msg_param_ffa_mem(struct optee *optee, struct tee_param *p,
> > >   * @params:  subsystem internal parameter representation
> > >   * @num_params:      number of elements in the parameter arrays
> > >   * @msg_params:      OPTEE_MSG parameters
> > > + * @update_out: update parameter for output only
> > >   *
> > >   * Returns 0 on success or <0 on failure
> > >   */
> > >  static int optee_ffa_from_msg_param(struct optee *optee,
> > >                                   struct tee_param *params, size_t num_params,
> > > -                                 const struct optee_msg_param *msg_params)
> > > +                                 const struct optee_msg_param *msg_params,
> > > +                                 bool update_out)
> > >  {
> > >       size_t n;
> > >
> > > @@ -166,18 +176,20 @@ static int optee_ffa_from_msg_param(struct optee *optee,
> > >
> > >               switch (attr) {
> > >               case OPTEE_MSG_ATTR_TYPE_NONE:
> > > +                     if (update_out)
> > > +                             break;
> > >                       p->attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
> > >                       memset(&p->u, 0, sizeof(p->u));
> > >                       break;
> > >               case OPTEE_MSG_ATTR_TYPE_VALUE_INPUT:
> > >               case OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT:
> > >               case OPTEE_MSG_ATTR_TYPE_VALUE_INOUT:
> > > -                     optee_from_msg_param_value(p, attr, mp);
> > > +                     optee_from_msg_param_value(p, attr, mp, update_out);
> > >                       break;
> > >               case OPTEE_MSG_ATTR_TYPE_FMEM_INPUT:
> > >               case OPTEE_MSG_ATTR_TYPE_FMEM_OUTPUT:
> > >               case OPTEE_MSG_ATTR_TYPE_FMEM_INOUT:
> > > -                     from_msg_param_ffa_mem(optee, p, attr, mp);
> > > +                     from_msg_param_ffa_mem(optee, p, attr, mp, update_out);
> > >                       break;
> > >               default:
> > >                       return -EINVAL;
> > > @@ -188,10 +200,16 @@ static int optee_ffa_from_msg_param(struct optee *optee,
> > >  }
> > >
> > >  static int to_msg_param_ffa_mem(struct optee_msg_param *mp,
> > > -                             const struct tee_param *p)
> > > +                             const struct tee_param *p, bool update_out)
> > >  {
> > >       struct tee_shm *shm = p->u.memref.shm;
> > >
> > > +     if (update_out) {
> > > +             if (p->attr == TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT)
> > > +                     return 0;
> > > +             goto out;
> > > +     }
> > > +
> > >       mp->attr = OPTEE_MSG_ATTR_TYPE_FMEM_INPUT + p->attr -
> > >                  TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
> > >
> > > @@ -211,6 +229,7 @@ static int to_msg_param_ffa_mem(struct optee_msg_param *mp,
> > >               memset(&mp->u, 0, sizeof(mp->u));
> > >               mp->u.fmem.global_id = OPTEE_MSG_FMEM_INVALID_GLOBAL_ID;
> > >       }
> > > +out:
> > >       mp->u.fmem.size = p->u.memref.size;
> > >
> > >       return 0;
> > > @@ -222,13 +241,15 @@ static int to_msg_param_ffa_mem(struct optee_msg_param *mp,
> > >   * @optee:   main service struct
> > >   * @msg_params:      OPTEE_MSG parameters
> > >   * @num_params:      number of elements in the parameter arrays
> > > - * @params:  subsystem itnernal parameter representation
> > > + * @params:  subsystem internal parameter representation
> > > + * @update_out: update parameter for output only
> > >   * Returns 0 on success or <0 on failure
> > >   */
> > >  static int optee_ffa_to_msg_param(struct optee *optee,
> > >                                 struct optee_msg_param *msg_params,
> > >                                 size_t num_params,
> > > -                               const struct tee_param *params)
> > > +                               const struct tee_param *params,
> > > +                               bool update_out)
> > >  {
> > >       size_t n;
> > >
> > > @@ -238,18 +259,20 @@ static int optee_ffa_to_msg_param(struct optee *optee,
> > >
> > >               switch (p->attr) {
> > >               case TEE_IOCTL_PARAM_ATTR_TYPE_NONE:
> > > +                     if (update_out)
> > > +                             break;
> > >                       mp->attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
> > >                       memset(&mp->u, 0, sizeof(mp->u));
> > >                       break;
> > >               case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT:
> > >               case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
> > >               case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
> > > -                     optee_to_msg_param_value(mp, p);
> > > +                     optee_to_msg_param_value(mp, p, update_out);
> > >                       break;
> > >               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 (to_msg_param_ffa_mem(mp, p))
> > > +                     if (to_msg_param_ffa_mem(mp, p, update_out))
> > >                               return -EINVAL;
> > >                       break;
> > >               default:
> >
> > Can we rather handle it as follows to improve code readability and
> > maintainence long term? Ditto for all other places.
> >
> > static int optee_ffa_to_msg_param(struct optee *optee,
> >                                   struct optee_msg_param *msg_params,
> >                                   size_t num_params,
> >                                   const struct tee_param *params,
> >                                   bool update_out)
> > {
> >         size_t n;
> >
> >         for (n = 0; n < num_params; n++) {
> >                 const struct tee_param *p = params + n;
> >                 struct optee_msg_param *mp = msg_params + n;
> >
> >                 if (update_out && (p->attr == TEE_IOCTL_PARAM_ATTR_TYPE_NONE ||
> >                      p->attr == TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT ||
> >                      p->attr == TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT))
> >                     continue;
> 
> You're missing updating the length field for memrefs.
>

Do we need to update length field for input memrefs when update_out is
set? I don't see that happening in your existing patch too.

-Sumit

> Cheers,
> Jens
> 
> >
> >                 switch (p->attr) {
> >                 case TEE_IOCTL_PARAM_ATTR_TYPE_NONE:
> >                         mp->attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
> >                         memset(&mp->u, 0, sizeof(mp->u));
> >                         break;
> >                 case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT:
> >                 case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
> >                 case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
> >                         optee_to_msg_param_value(mp, p);
> >                         break;
> >                 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 (to_msg_param_ffa_mem(mp, p))
> >                                 return -EINVAL;
> >                         break;
> >                 default:
> >                         return -EINVAL;
> >                 }
> >         }
> >
> >         return 0;
> > }
> >
> > -Sumit