Re: [PATCH 1/6] tee: qcomtee: Track the object invocation context

[Harshal Dev]

Hi Amir,

On 7/8/2026 11:31 AM, Amirreza Zarrabi wrote:
> Hi Harshal,
> 
> On 7/7/2026 4:11 PM, Harshal Dev wrote:
>> QCOMTEE needs to distinguish between object invocations arriving from
>> kernel clients and user-space clients in order to correctly marshal
>> UBUF parameters and decide whether certain operations should be permitted.
>>
>> Add a kernel_ctx flag to struct qcomtee_object_invoke_context to track
>> the context of object invocation. Objects invoked from the kernel-space
>> are expected to have the MSB of their 64-bit object-id set to indicate a
>> kernel context, whereas objects invoked from user-space should not set it.
>> To ensure this, we restrict the object-id space of user-space invoked
>> objects to 32-bits. This is in-line with QTEE expectation of 32-bit object
>> ids.
>>
>> Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Harshal Dev <harshal.dev@xxxxxxxxxxxxxxxx>
>> ---
>>  drivers/tee/qcomtee/call.c           | 24 ++++++++++++++++++++++--
>>  drivers/tee/qcomtee/qcomtee.h        |  6 ++++++
>>  drivers/tee/qcomtee/qcomtee_object.h |  8 ++++++--
>>  drivers/tee/tee_core.c               |  4 ++++
>>  4 files changed, 38 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/tee/qcomtee/call.c b/drivers/tee/qcomtee/call.c
>> index 0efc5646242a..a74a54d67b06 100644
>> --- a/drivers/tee/qcomtee/call.c
>> +++ b/drivers/tee/qcomtee/call.c
>> @@ -397,11 +397,31 @@ static int qcomtee_object_invoke(struct tee_context *ctx,
>>  {
>>  	struct qcomtee_context_data *ctxdata = ctx->data;
>>  	struct qcomtee_object *object;
>> +	bool kernel_ctx = false;
>>  	int i, ret, result;
>>  
>>  	if (qcomtee_params_check(params, arg->num_params))
>>  		return -EINVAL;
>>  
>> +	/* Obtain the invocation context information from the MSB of the object
>> +	 * `id` field.
>> +	 */
>> +	kernel_ctx = QCOMTEE_GET_CLIENT_CTX(arg->id);
>> +	/* User-space identifies a NULL object via a 32-bit TEE_OBJREF_NULL id, whereas
>> +	 * the kernel uses as 64-bit object-id. Hence, we check for a NULL object by
>> +	 * sign-extending the object-id to 64 bits. If user-space is indeed invoking a
>> +	 * NULL object we must extend the object-id to 64-bits from here on so that
>> +	 * QCOMTEE can recognize it.
>> +	 */
>> +	if (!kernel_ctx && ((s64)(s32)arg->id) == TEE_OBJREF_NULL)
>> +		arg->id = TEE_OBJREF_NULL;
> 
> Does it need to be MSB -- why bit 63? the object ID supported by QTEE is 32-bit anyway.
> Let's mask the upper 32-bit and do something like kernel_ctx = !!upper_32_bits(id).
> What do you think?

I agree. Instead of checking for kernel-ctx by right shifting, I can use this approach.
QTEE objects invoked from user-space (including NULL object) will always have their
object-id constrained to lower 32 bits anyway as per PR: https://github.com/quic/quic-teec/pull/27

And for kernel-space invoked QTEE objects, upper 32-bits would be set for NULL object,
and 63rd bit expected to be set as well.

> 
>> +
>> +	/* If the object being invoked is not NULL, drop the MSB from the `id` field to
>> +	 * obtain the actual object-id.
>> +	 */
>> +	if (arg->id != TEE_OBJREF_NULL)
>> +		arg->id = QCOMTEE_SANITIZE_OBJ_ID(arg->id);
>> +
>>  	/* First, handle reserved operations: */
>>  	if (arg->op == QCOMTEE_MSG_OBJECT_OP_RELEASE) {
>>  		del_qtee_object(arg->id, ctxdata);
>> @@ -411,7 +431,7 @@ static int qcomtee_object_invoke(struct tee_context *ctx,
>>  
>>  	/* Otherwise, invoke a QTEE object: */
>>  	struct qcomtee_object_invoke_ctx *oic __free(kfree) =
>> -		qcomtee_object_invoke_ctx_alloc(ctx);
>> +		qcomtee_object_invoke_ctx_alloc(ctx, kernel_ctx);
>>  	if (!oic)
>>  		return -ENOMEM;
>>  
>> @@ -648,7 +668,7 @@ static void qcomtee_get_qtee_feature_list(struct tee_context *ctx, u32 id,
>>  	int result;
>>  
>>  	struct qcomtee_object_invoke_ctx *oic __free(kfree) =
>> -		qcomtee_object_invoke_ctx_alloc(ctx);
>> +		qcomtee_object_invoke_ctx_alloc(ctx, true);
>>  	if (!oic)
>>  		return;
>>  
>> diff --git a/drivers/tee/qcomtee/qcomtee.h b/drivers/tee/qcomtee/qcomtee.h
>> index f39bf63fd1c2..5d292a2ff83d 100644
>> --- a/drivers/tee/qcomtee/qcomtee.h
>> +++ b/drivers/tee/qcomtee/qcomtee.h
>> @@ -17,6 +17,12 @@
>>  #define QCOMTEE_OBJREF_FLAG_USER	BIT(1)
>>  #define QCOMTEE_OBJREF_FLAG_MEM		BIT(2)
>>  
>> +/* The MSB of the object_id field indicates whether the client is invoking the
>> + * object from user context or kernel context.
>> + */
>> +#define QCOMTEE_GET_CLIENT_CTX(x) (((x) >> 63) & 1U)
>> +#define QCOMTEE_SANITIZE_OBJ_ID(x) ((x) & (BIT(63) - 1))
>> +
>>  /**
>>   * struct qcomtee - Main service struct.
>>   * @teedev: client device.
>> diff --git a/drivers/tee/qcomtee/qcomtee_object.h b/drivers/tee/qcomtee/qcomtee_object.h
>> index 8b4401ecad48..2528d07e4576 100644
>> --- a/drivers/tee/qcomtee/qcomtee_object.h
>> +++ b/drivers/tee/qcomtee/qcomtee_object.h
>> @@ -146,6 +146,7 @@ static inline int qcomtee_args_len(struct qcomtee_arg *args)
>>   * struct qcomtee_object_invoke_ctx - QTEE context for object invocation.
>>   * @ctx: TEE context for this invocation.
>>   * @flags: flags for the invocation context.
>> + * @kernel_ctx: flag that indicates this context is owned by a kernel client.
>>   * @errno: error code for the invocation.
>>   * @object: current object invoked in this callback context.
>>   * @u: array of arguments for the current invocation (+1 for ending arg).
>> @@ -158,6 +159,7 @@ static inline int qcomtee_args_len(struct qcomtee_arg *args)
>>  struct qcomtee_object_invoke_ctx {
>>  	struct tee_context *ctx;
>>  	unsigned long flags;
>> +	bool kernel_ctx;
>>  	int errno;
>>  
>>  	struct qcomtee_object *object;
>> @@ -172,13 +174,15 @@ struct qcomtee_object_invoke_ctx {
>>  };
>>  
>>  static inline struct qcomtee_object_invoke_ctx *
>> -qcomtee_object_invoke_ctx_alloc(struct tee_context *ctx)
>> +qcomtee_object_invoke_ctx_alloc(struct tee_context *ctx, bool kernel_ctx)
>>  {
>>  	struct qcomtee_object_invoke_ctx *oic;
>>  
>>  	oic = kzalloc_obj(*oic);
>> -	if (oic)
>> +	if (oic) {
>>  		oic->ctx = ctx;
>> +		oic->kernel_ctx = kernel_ctx;
>> +	}
>>  	return oic;
>>  }
>>  
>> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
>> index ef9642d72672..7f986d7fb47f 100644
>> --- a/drivers/tee/tee_core.c
>> +++ b/drivers/tee/tee_core.c
>> @@ -706,6 +706,10 @@ static int tee_ioctl_object_invoke(struct tee_context *ctx,
>>  			goto out;
>>  	}
>>  
>> +	/* Userspace object-ids are restricted to 32-bits. */
>> +	if (arg.id > U32_MAX)
>> +		return -EINVAL;
>> +
> 
> This change belongs to tee SS, move it to a separate commit with appropriate message.

Ack.

Regards,
Harshal
> 
>>  	rc = ctx->teedev->desc->ops->object_invoke_func(ctx, &arg, params);
>>  	if (rc)
>>  		goto out;
>>
> 
> Regards,
> Amir
>