On Thu, 26 Mar 2020 at 14:05, Jérôme Forissier <[email protected]> wrote:
>
> On Thu, Mar 26, 2020 at 8:24 AM Sumit Garg <[email protected]> wrote:
>>
>> There are use-cases where user-space shouldn't be allowed to communicate
>> directly with a TEE device which is dedicated to provide a specific
>> service for a kernel client. So add a private login method for kernel
>> clients
>
>
> OK
>
>> and disallow user-space to open-session using GP implementation
>> defined login method range: (0x80000000 - 0xFFFFFFFF).
>
>
> I'm not sure this is correct, because it would prevent the client library or the TEE supplicant from using such values, although they are part of the TEE implementation; and further, nothing mandates that an implementation-defined method should not be used directly by client applications.
>
Initial implementation of this patch only put restriction for single
implementation-defined login method (TEE_IOCTL_LOGIN_REE_KERNEL) only.
But after discussion with Jens here [1], I have changed that to
restrict complete implementation-defined range. If we think to further
partition this range considering API stability then I am open to that
too.
[1] https://lore.kernel.org/patchwork/patch/1088062/
-Sumit
> --
> Jerome
>
>>
>>
>> Signed-off-by: Sumit Garg <[email protected]>
>> ---
>> drivers/tee/tee_core.c | 6 ++++++
>> include/uapi/linux/tee.h | 8 ++++++++
>> 2 files changed, 14 insertions(+)
>>
>> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
>> index 37d22e3..533e7a8 100644
>> --- a/drivers/tee/tee_core.c
>> +++ b/drivers/tee/tee_core.c
>> @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
>> goto out;
>> }
>>
>> + if (arg.clnt_login & TEE_IOCTL_LOGIN_MASK) {
>> + pr_debug("login method not allowed for user-space client\n");
>> + rc = -EPERM;
>> + goto out;
>> + }
>> +
>> rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
>> if (rc)
>> goto out;
>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>> index 6596f3a..19172a2 100644
>> --- a/include/uapi/linux/tee.h
>> +++ b/include/uapi/linux/tee.h
>> @@ -173,6 +173,14 @@ struct tee_ioctl_buf_data {
>> #define TEE_IOCTL_LOGIN_APPLICATION 4
>> #define TEE_IOCTL_LOGIN_USER_APPLICATION 5
>> #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6
>> +/*
>> + * Disallow user-space to use GP implementation specific login
>> + * method range (0x80000000 - 0xFFFFFFFF). This range is rather
>> + * being reserved for REE kernel clients or TEE implementation.
>> + */
>> +#define TEE_IOCTL_LOGIN_MASK 0x80000000
>> +/* Private login method for REE kernel clients */
>> +#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000
>>
>> /**
>> * struct tee_ioctl_param - parameter
>> --
>> 2.7.4
>>
>> _______________________________________________
>> Tee-dev mailing list
>> [email protected]
>> https://lists.linaro.org/mailman/listinfo/tee-dev
On 3/26/20 10:07 AM, Sumit Garg wrote:
> On Thu, 26 Mar 2020 at 14:05, Jérôme Forissier <[email protected]> wrote:
>>
>> On Thu, Mar 26, 2020 at 8:24 AM Sumit Garg <[email protected]> wrote:
>>>
>>> There are use-cases where user-space shouldn't be allowed to communicate
>>> directly with a TEE device which is dedicated to provide a specific
>>> service for a kernel client. So add a private login method for kernel
>>> clients
>>
>>
>> OK
>>
>>> and disallow user-space to open-session using GP implementation
>>> defined login method range: (0x80000000 - 0xFFFFFFFF).
>>
>>
>> I'm not sure this is correct, because it would prevent the client library or the TEE supplicant from using such values, although they are part of the TEE implementation; and further, nothing mandates that an implementation-defined method should not be used directly by client applications.
>>
>
> Initial implementation of this patch only put restriction for single
> implementation-defined login method (TEE_IOCTL_LOGIN_REE_KERNEL) only.
> But after discussion with Jens here [1], I have changed that to
> restrict complete implementation-defined range. If we think to further
> partition this range considering API stability then I am open to that
> too.
>
> [1] https://lore.kernel.org/patchwork/patch/1088062/
In the end he proposed to reserve half the range for user space and half
for kernel space.
(BTW sorry for my previous HTML reply)
--
Jerome
>
> -Sumit
>
>> --
>> Jerome
>>
>>>
>>>
>>> Signed-off-by: Sumit Garg <[email protected]>
>>> ---
>>> drivers/tee/tee_core.c | 6 ++++++
>>> include/uapi/linux/tee.h | 8 ++++++++
>>> 2 files changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
>>> index 37d22e3..533e7a8 100644
>>> --- a/drivers/tee/tee_core.c
>>> +++ b/drivers/tee/tee_core.c
>>> @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
>>> goto out;
>>> }
>>>
>>> + if (arg.clnt_login & TEE_IOCTL_LOGIN_MASK) {
>>> + pr_debug("login method not allowed for user-space client\n");
>>> + rc = -EPERM;
>>> + goto out;
>>> + }
>>> +
>>> rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
>>> if (rc)
>>> goto out;
>>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>>> index 6596f3a..19172a2 100644
>>> --- a/include/uapi/linux/tee.h
>>> +++ b/include/uapi/linux/tee.h
>>> @@ -173,6 +173,14 @@ struct tee_ioctl_buf_data {
>>> #define TEE_IOCTL_LOGIN_APPLICATION 4
>>> #define TEE_IOCTL_LOGIN_USER_APPLICATION 5
>>> #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6
>>> +/*
>>> + * Disallow user-space to use GP implementation specific login
>>> + * method range (0x80000000 - 0xFFFFFFFF). This range is rather
>>> + * being reserved for REE kernel clients or TEE implementation.
>>> + */
>>> +#define TEE_IOCTL_LOGIN_MASK 0x80000000
>>> +/* Private login method for REE kernel clients */
>>> +#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000
>>>
>>> /**
>>> * struct tee_ioctl_param - parameter
>>> --
>>> 2.7.4
>>>
>>> _______________________________________________
>>> Tee-dev mailing list
>>> [email protected]
>>> https://lists.linaro.org/mailman/listinfo/tee-dev
On Thu, 26 Mar 2020 at 14:53, Jerome Forissier <[email protected]> wrote:
>
> On 3/26/20 10:07 AM, Sumit Garg wrote:
> > On Thu, 26 Mar 2020 at 14:05, Jérôme Forissier <[email protected]> wrote:
> >>
> >> On Thu, Mar 26, 2020 at 8:24 AM Sumit Garg <[email protected]> wrote:
> >>>
> >>> There are use-cases where user-space shouldn't be allowed to communicate
> >>> directly with a TEE device which is dedicated to provide a specific
> >>> service for a kernel client. So add a private login method for kernel
> >>> clients
> >>
> >>
> >> OK
> >>
> >>> and disallow user-space to open-session using GP implementation
> >>> defined login method range: (0x80000000 - 0xFFFFFFFF).
> >>
> >>
> >> I'm not sure this is correct, because it would prevent the client library or the TEE supplicant from using such values, although they are part of the TEE implementation; and further, nothing mandates that an implementation-defined method should not be used directly by client applications.
> >>
> >
> > Initial implementation of this patch only put restriction for single
> > implementation-defined login method (TEE_IOCTL_LOGIN_REE_KERNEL) only.
> > But after discussion with Jens here [1], I have changed that to
> > restrict complete implementation-defined range. If we think to further
> > partition this range considering API stability then I am open to that
> > too.
> >
> > [1] https://lore.kernel.org/patchwork/patch/1088062/
>
> In the end he proposed to reserve half the range for user space and half
> for kernel space.
It seems I probably misunderstood his proposal. So let me reserve
(0x80000000 - 0xBFFFFFFF) range for kernel space.
>
> (BTW sorry for my previous HTML reply)
>
No worries.
-Sumit
> --
> Jerome
> >
> > -Sumit
> >
> >> --
> >> Jerome
> >>
> >>>
> >>>
> >>> Signed-off-by: Sumit Garg <[email protected]>
> >>> ---
> >>> drivers/tee/tee_core.c | 6 ++++++
> >>> include/uapi/linux/tee.h | 8 ++++++++
> >>> 2 files changed, 14 insertions(+)
> >>>
> >>> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> >>> index 37d22e3..533e7a8 100644
> >>> --- a/drivers/tee/tee_core.c
> >>> +++ b/drivers/tee/tee_core.c
> >>> @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
> >>> goto out;
> >>> }
> >>>
> >>> + if (arg.clnt_login & TEE_IOCTL_LOGIN_MASK) {
> >>> + pr_debug("login method not allowed for user-space client\n");
> >>> + rc = -EPERM;
> >>> + goto out;
> >>> + }
> >>> +
> >>> rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
> >>> if (rc)
> >>> goto out;
> >>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
> >>> index 6596f3a..19172a2 100644
> >>> --- a/include/uapi/linux/tee.h
> >>> +++ b/include/uapi/linux/tee.h
> >>> @@ -173,6 +173,14 @@ struct tee_ioctl_buf_data {
> >>> #define TEE_IOCTL_LOGIN_APPLICATION 4
> >>> #define TEE_IOCTL_LOGIN_USER_APPLICATION 5
> >>> #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6
> >>> +/*
> >>> + * Disallow user-space to use GP implementation specific login
> >>> + * method range (0x80000000 - 0xFFFFFFFF). This range is rather
> >>> + * being reserved for REE kernel clients or TEE implementation.
> >>> + */
> >>> +#define TEE_IOCTL_LOGIN_MASK 0x80000000
> >>> +/* Private login method for REE kernel clients */
> >>> +#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000
> >>>
> >>> /**
> >>> * struct tee_ioctl_param - parameter
> >>> --
> >>> 2.7.4
> >>>
> >>> _______________________________________________
> >>> Tee-dev mailing list
> >>> [email protected]
> >>> https://lists.linaro.org/mailman/listinfo/tee-dev