From patchwork Thu Oct 29 08:21:28 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Wiklander X-Patchwork-Id: 55747 Delivered-To: patches@linaro.org Received: by 10.112.61.134 with SMTP id p6csp403938lbr; Thu, 29 Oct 2015 01:22:13 -0700 (PDT) X-Received: by 10.112.170.228 with SMTP id ap4mr245756lbc.25.1446106926558; Thu, 29 Oct 2015 01:22:06 -0700 (PDT) Return-Path: Received: from mail-lb0-x236.google.com (mail-lb0-x236.google.com. [2a00:1450:4010:c04::236]) by mx.google.com with ESMTPS id xj7si269232lbb.163.2015.10.29.01.22.06 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Oct 2015 01:22:06 -0700 (PDT) Received-SPF: pass (google.com: domain of jens.wiklander@linaro.org designates 2a00:1450:4010:c04::236 as permitted sender) client-ip=2a00:1450:4010:c04::236; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jens.wiklander@linaro.org designates 2a00:1450:4010:c04::236 as permitted sender) smtp.mailfrom=jens.wiklander@linaro.org; dkim=pass header.i=@linaro_org.20150623.gappssmtp.com Received: by lbbes7 with SMTP id es7so22880466lbb.2 for ; Thu, 29 Oct 2015 01:22:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro_org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=w4u0xjfsejph72yN5N9yDIbGGerys5bxnDfvxj5JrME=; b=Ywm5Iz2bo/C7Mbt58WGlswKev1nsH8m6dEKersneprZLuFV6rVG6/qbwYPjIboKulj B7OhOcUc9WuzKTseo3K2pZ9mS2ipad6ILk2RR+uSzpa44S5r1EyJntfRSVL294DxBaU2 C7GOgs4+2L3CNVjqaMjkok4qXonDaxpp99RD7jScRCTLPEv2mmnhwjinSPBX7SODXXMJ PZBEd4THA10K/REitm7blPnsoiZ5dP7TZw0TnR+PBvjRSDS5YOuYz+hBAFuuaUqAI68K rFUdkyJ1XZ1YhgUYS3FqT8QTYLg2qJh8efs59OrSPvz+qktFB+88MD3p/j/jRz7L+aYs oqIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=w4u0xjfsejph72yN5N9yDIbGGerys5bxnDfvxj5JrME=; b=d4bbh6F1RUoLevYMbGVj8phR4kvmtOlfTwLz3JM6Pb8JN0zkA/Jg26qrUZI/yWjk0L a2RIwCKgsZN2YqF2jEmQG9dxDZuDScL9EveXqCz84lCoyIGDgEPQF1O+aQRLnZZL+9Gd UiVGeR3dG863nb0vY6YpJt39aof4S0/F/zWwhjg3THT80LMFYFWJ/Fl74BcwHHQTJZEA /Sb3vimwIHiTY7iNhL0g4nucRvqgqbIzlgojLl8GFkykKlTuRGa+J4/s+1g18WJ4G7pq bnqXRUgCxoRH2SqIvbYViYHX28Ma9oe90PdUCitUEH/RqpPdquBun0bT6xN9szLVTXja NSTQ== X-Gm-Message-State: ALoCoQmGdsBqGusevW/O066tLf3wKxoBjH0sm2SQyHc3YLX0w6FdyO9qzd9fO/RDxooTlvMDCxLq X-Received: by 10.112.209.71 with SMTP id mk7mr263277lbc.46.1446106926414; Thu, 29 Oct 2015 01:22:06 -0700 (PDT) Return-Path: Received: from ermac.ideon.se ([85.235.10.227]) by smtp.gmail.com with ESMTPSA id q201sm73103lfe.43.2015.10.29.01.22.04 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 29 Oct 2015 01:22:05 -0700 (PDT) From: Jens Wiklander To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Arnd Bergmann , Greg Kroah-Hartman , Kees Cook Cc: valentin.manea@huawei.com, jean-michel.delorme@st.com, emmanuel.michel@st.com, javier@javigon.com, Jason Gunthorpe , Mark Rutland , Michal Simek , Rob Herring , Will Deacon , Jens Wiklander Subject: [PATCH v6 6/6] Documentation: tee subsystem and op-tee driver Date: Thu, 29 Oct 2015 09:21:28 +0100 Message-Id: <1446106888-8983-7-git-send-email-jens.wiklander@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1446106888-8983-1-git-send-email-jens.wiklander@linaro.org> References: <1446106888-8983-1-git-send-email-jens.wiklander@linaro.org> Signed-off-by: Jens Wiklander --- Documentation/00-INDEX | 2 + Documentation/tee.txt | 117 +++++++++++++++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 120 insertions(+) create mode 100644 Documentation/tee.txt -- 1.9.1 diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index cd077ca..bd3f803 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -435,6 +435,8 @@ sysrq.txt - info on the magic SysRq key. target/ - directory with info on generating TCM v4 fabric .ko modules +tee.txt + - info on the TEE subsystem and drivers this_cpu_ops.txt - List rationale behind and the way to use this_cpu operations. thermal/ diff --git a/Documentation/tee.txt b/Documentation/tee.txt new file mode 100644 index 0000000..4ac91d2 --- /dev/null +++ b/Documentation/tee.txt @@ -0,0 +1,117 @@ +TEE subsystem +This document describes the TEE subsystem in Linux + +A TEE (Trusted Execution Environment) is a trusted OS running in some +secure environment, for example, TrustZone on ARM CPUs, or a separate +secure co-processor etc. A TEE driver handles the details needed to +communicate with the TEE. + +This subsystem deals with: + +- Registration of TEE drivers + +- Managing shared memory between Linux and the TEE + +- Providing a generic API to the TEE + +The TEE interface +================= + +include/uapi/linux/tee.h defines the generic interface to a TEE. + +User space (the client) connects to the driver by opening /dev/tee[0-9]* or +/dev/teepriv[0-9]*. + +- TEE_IOC_SHM_ALLOC allocates shared memory and returns a file descriptor which + user space can mmap. When user space doesn't need the file descriptor anymore + it should be closed. When shared memory isn't needed any longer it should be + unmapped with munmap() to allow the reuse of memory. + +- TEE_IOC_VERSION lets user space know which TEE this driver handles and + the its capabilities. + +- TEE_IOC_OPEN_SESSION opens a new session to a Trusted Application + +- TEE_IOC_INVOKE invokes a function in a Trusted Application + +- TEE_IOC_CANCEL may cancel an ongoing TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE + +- TEE_IOC_CLOSE_SESSION closes a session to a Trusted Application + +There are two classes of clients, normal clients and supplicants. The latter is +a helper process for the TEE to access resources in Linux, for example file +system access. A normal client opens /dev/tee[0-9]* and a supplicant opens +/dev/teepriv[0-9]. + +Much of the communication between clients and the TEE is opaque to the +driver. The main job for the driver is to receive requests from the +clients, forward them to the TEE and send back the results. In the case of +supplicants the communication goes in the other direction, the TEE sends +requests to the supplicant which then sends back the result. + +OP-TEE driver +============= + +The OP-TEE driver handles OP-TEE [1] based TEEs. Currently it is only the ARM +TrustZone based OP-TEE solution that is supported. + +Lowest level of communication with OP-TEE builds on ARM SMC Calling +Convention (SMCCC) [2], which is the foundation for OP-TEE's SMC interface +[3] used internally by the driver. Stacked on top of that is OP-TEE Message +Protocol [4]. + +OP-TEE SMC interface provides the basic functions required by SMCCC and some +additional functions specific for OP-TEE. The most interesting functions are: + +- OPTEE_SMC_FUNCID_CALLS_UID (part of SMCCC) returns the version information + which is then returned by TEE_IOC_VERSION + +- OPTEE_SMC_CALL_GET_OS_UUID returns the particular OP-TEE implementation, used + to tell, for instance, a TrustZone OP-TEE apart from an OP-TEE running on a + separate secure co-processor. + +- OPTEE_SMC_CALL_WITH_ARG drives the OP-TEE message protocol + +- OPTEE_SMC_GET_SHM_CONFIG lets the driver and OP-TEE agree on which memory + range to used for shared memory between Linux and OP-TEE. + +The GlobalPlatform TEE Client API [5] is implemented on top of the generic +TEE API. + +Picture of the relationship between the different components in the +OP-TEE architecture. + + User space Kernel Secure world + ~~~~~~~~~~ ~~~~~~ ~~~~~~~~~~~~ + +--------+ +-------------+ + | Client | | Trusted | + +--------+ | Application | + /\ +-------------+ + || +----------+ /\ + || |tee- | || + || |supplicant| \/ + || +----------+ +-------------+ + \/ /\ | TEE Internal| + +-------+ || | API | + + TEE | || +--------+--------+ +-------------+ + | Client| || | TEE | OP-TEE | | OP-TEE | + | API | \/ | subsys | driver | | Trusted OS | + +-------+----------------+----+-------+----+-----------+-------------+ + | Generic TEE API | | OP-TEE MSG | + | IOCTL (TEE_IOC_*) | | SMCCC (OPTEE_SMC_CALL_*) | + +-----------------------------+ +------------------------------+ + +RPC (Remote Procedure Call) are requests from secure world to kernel driver +or tee-supplicant. An RPC is identified by a special range of SMCCC return +values from OPTEE_SMC_CALL_WITH_ARG. RPC messages which are intended for the +kernel are handled by the kernel driver. Other RPC messages will be forwarded to +tee-supplicant without further involvement of the driver, except switching +shared memory buffer representation. + +References: +[1] https://github.com/OP-TEE/optee_os +[2] http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html +[3] drivers/tee/optee/optee_smc.h +[4] drivers/tee/optee/optee_msg.h +[5] http://www.globalplatform.org/specificationsdevice.asp look for + "TEE Client API Specification v1.0" and click download. diff --git a/MAINTAINERS b/MAINTAINERS index e9be205..bcce97b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9144,6 +9144,7 @@ S: Maintained F: include/linux/tee_drv.h F: include/uapi/linux/tee.h F: drivers/tee/ +F: Documentation/tee.txt THUNDERBOLT DRIVER M: Andreas Noever