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[79.136.84.105]) by smtp.gmail.com with ESMTPSA id g4sm2832994lfb.31.2019.07.08.08.39.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 08 Jul 2019 08:39:11 -0700 (PDT) Date: Mon, 8 Jul 2019 17:39:09 +0200 From: Jens Wiklander To: Sumit Garg Cc: keyrings@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, corbet@lwn.net, dhowells@redhat.com, jejb@linux.ibm.com, jarkko.sakkinen@linux.intel.com, zohar@linux.ibm.com, jmorris@namei.org, serge@hallyn.com, ard.biesheuvel@linaro.org, daniel.thompson@linaro.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, tee-dev@lists.linaro.org Subject: Re: [RFC 3/7] tee: add private login method for kernel clients Message-ID: <20190708153908.GA28253@jax> References: <1560421833-27414-1-git-send-email-sumit.garg@linaro.org> <1560421833-27414-4-git-send-email-sumit.garg@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1560421833-27414-4-git-send-email-sumit.garg@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sumit, On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg 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 and disallow user-space to open-session using this login method. > > Signed-off-by: Sumit Garg > --- > drivers/tee/tee_core.c | 6 ++++++ > include/uapi/linux/tee.h | 2 ++ > 2 files changed, 8 insertions(+) > > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c > index 0f16d9f..4581bd1 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_REE_KERNEL) { TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the range specified and implementation defined by the GP spec. I wonder if we shouldn't filter the entire implementation defined range instead of just this value. > + pr_err("login method not allowed for user-space client\n"); pr_debug(), if it's needed at all. > + 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 4b9eb06..f33c69c 100644 > --- a/include/uapi/linux/tee.h > +++ b/include/uapi/linux/tee.h > @@ -172,6 +172,8 @@ 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 > +/* Private login method for REE kernel clients */ It's worth noting that this is filtered by the TEE framework, compared to everything else which is treated opaquely. > +#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000 > > /** > * struct tee_ioctl_param - parameter > -- > 2.7.4 > Thanks, Jens