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

[Harshal Dev]

Hi Sumit,

On 17-07-2026 01:56 pm, Sumit Garg wrote:
> On Thu, Jul 16, 2026 at 12:28:25PM +0530, Harshal Dev wrote:
>> Hi Amir,
>>
>> On 7/15/2026 5:17 AM, Amirreza Zarrabi wrote:
>>> Hi Harshal,
>>>
>>> On 7/10/2026 4:37 PM, Harshal Dev wrote:
>>>> 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.
>>>>
>>>
>>> Re-thinking this, I'm a bit concerned about overloading id while keeping it as a u64,
>>> and then filtering its upper 32 bits in tee_ioctl_object_invoke(). It feels unintuitive,
>>> as it naturally raises the question: if only the lower 32 bits are meaningful,
>>> why is id a `u64` in the first place?
>>>
>>> What if we make the caller origin explicit instead, for example:
>>>
>>> enum tee_object_invoke_origin {
>>> 	TEE_OBJECT_INVOKE_USERSPACE,
>>> 	TEE_OBJECT_INVOKE_KERNEL,
>>> };
>>>
>>> and then pass it through the backend op:
>>>
>>> int (*object_invoke_func)(struct tee_context *ctx,
>>> 			  struct tee_ioctl_object_invoke_arg *arg,
>>> 			  struct tee_param *param,
>>> 			  enum tee_object_invoke_origin origin);
>>>
>>> It seems more straightforward and avoids encoding caller-origin metadata into id.
>>> If you are OK, let's do this.
>>>
>>
>> Honestly, this approach makes everything a lot more easier, since we don't need complex
>> bit manipulation in back-end to filter the upper 32 bits and handle the case of
>> TEE_OBJREF_NULL. I can also then drop the PR: https://github.com/quic/quic-teec/pull/27
>>
>> I am fine with updating this callback and calling it with TEE_OBJECT_INVOKE_USERSPACE from
>> https://elixir.bootlin.com/linux/v7.1/source/drivers/tee/tee_core.c#L704
>> and TEE_OBJECT_INVOKE_KERNEL from the newly introduced tee_client_object_invoke_func().
>>
>> But is there any special reason for choosing an enum over a boolean value here? Are we planning
>> to extend the enum later to introduce any other context information?
> 
> I think enum is just better to provide enough info for the flag.
>

Ack.

>>
>> I am fine with this approach. I hope the OP-TEE maintainers @Sumit are fine as well with the
>> new parameter addition in the callback.
> 
> That's fine with me if it simplifies the object handling for you folks.

Ack, thank you for your review, I will spin a v2 based on this feedback.

Regards,
Harshal

> 
> -Sumit