Messages in this thread | | | From | Sumit Garg <> | Date | Thu, 26 Mar 2020 14:37:29 +0530 | Subject | Re: [Tee-dev] [PATCH v5 2/2] tee: add private login method for kernel clients |
| |
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/
-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
| |