Messages in this thread Patch in this message | | | From | Sumit Garg <> | Date | Thu, 26 Mar 2020 15:09:08 +0530 | Subject | Re: [Tee-dev] [PATCH v5 2/2] tee: add private login method for kernel clients |
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On Thu, 26 Mar 2020 at 14:53, Jerome Forissier <jerome@forissier.org> wrote: > > 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.
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 <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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