26 Mar
2020
26 Mar
'20
8:35 a.m.
On Thu, Mar 26, 2020 at 8:24 AM Sumit Garg sumit.garg@linaro.org 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.
--
Jerome
>
> Signed-off-by: Sumit Garg sumit.garg@linaro.org
> ---
> 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
>
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