Messages in this thread | | | Subject | Re: [Tee-dev] [PATCH v5 2/2] tee: add private login method for kernel clients | From | Jerome Forissier <> | Date | Thu, 26 Mar 2020 10:23:33 +0100 |
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On 3/26/20 10:07 AM, Sumit Garg wrote: > On Thu, 26 Mar 2020 at 14:05, Jérôme Forissier <jerome@forissier.org> wrote: >> >> 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. >> > > 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 <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 >>> >>> _______________________________________________ >>> Tee-dev mailing list >>> Tee-dev@lists.linaro.org >>> https://lists.linaro.org/mailman/listinfo/tee-dev
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