[PATCH v8 0/4] generic TEE subsystem
Andreas Dannenberg
dannenberg at ti.com
Wed Mar 2 03:15:48 PST 2016
On Thu, Feb 11, 2016 at 06:14:33PM +0100, Jens Wiklander wrote:
> Hi,
>
> This patch set introduces a generic TEE subsystem. The TEE subsystem will
> contain drivers for various TEE implementations. 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.
>
> Regarding use cases, TrustZone has traditionally been used for
> offloading secure tasks to the secure world. Examples include:
> - Secure key handling where the OS may or may not have direct access to key
> material.
> - E-commerce and payment technologies. Credentials, credit card numbers etc
> could be stored in a more secure environment.
> - Trusted User Interface (TUI) to ensure that no-one can snoop PIN-codes
> etc.
> - Secure boot to ensure that loaded binaries haven’t been tampered with.
> It’s not strictly needed for secure boot, but you could enhance security
> by leveraging a TEE during boot.
> - Digital Rights Management (DRM), the studios provides content with
> different resolution depending on the security of the device. Higher
> security means higher resolution.
>
> A TEE could also be used in existing and new technologies. For example IMA
> (Integrity Measurement Architecture) which has been in the kernel for quite
> a while. Today you can enhance security by using a TPM-chip to sign the IMA
> measurement list. This is something that you also could do by leveraging a
> TEE.
>
> Another example could be in 2-factor authentication which is becoming
> increasingly more important. FIDO (https://fidoalliance.org) for example
> are using public key cryptography in their 2-factor authentication standard
> (U2F). With FIDO, a private and public key pair will be generated for every
> site you visit and the private key should never leave the local device.
> This is an example where you could use secure storage in a TEE for the
> private key.
>
> Today you will find a quite a few different out of tree implementations of
> TEE drivers which tends to fragment the TEE ecosystem and development. We
> think it would be a good idea to have a generic TEE driver integrated in
> the kernel which would serve as a base for several different TEE solutions,
> no matter if they are on-chip like TrustZone or if they are on a separate
> crypto co-processor.
>
> To develop this TEE subsystem we have been using the open source TEE called
> OP-TEE (https://github.com/OP-TEE/optee_os) and therefore this would be the
> first TEE solution supported by this new subsystem. OP-TEE is a
> GlobalPlatform compliant TEE, however this TEE subsystem is not limited to
> only GlobalPlatform TEEs, instead we have tried to design it so that it
> should work with other TEE solutions also.
>
> "tee: generic TEE subsystem" brings in the generic TEE subsystem which
> helps when writing a driver for a specific TEE, for example, OP-TEE.
>
> "tee: add OP-TEE driver" is an OP-TEE driver which uses the subsystem to do
> its work.
>
> This patch set has been prepared in cooperation with Javier González who
> proposed "Generic TrustZone Driver in Linux Kernel" patches 28 Nov 2014,
> https://lwn.net/Articles/623380/ . We've since then changed the scope to
> TEE instead of TrustZone.
>
> We have discussed the design on tee-dev at lists.linaro.org (archive at
> https://lists.linaro.org/pipermail/tee-dev/) with people from other
> companies, including Valentin Manea <valentin.manea at huawei.com>,
> Emmanuel MICHEL <emmanuel.michel at st.com>,
> Jean-michel DELORME <jean-michel.delorme at st.com>,
> and Joakim Bech <joakim.bech at linaro.org>. Our main concern has been to
> agree on something that is generic enough to support many different
> TEEs while still keeping the interface together.
>
> v8:
> * Rebased on v4.5-rc3
> * dt/bindings: add bindings for optee
> Acked-by: Rob Herring <robh at kernel.org>
> * Fixes build error for X86
> * Fixes spell error in "dt/bindings: add bindings for optee"
Jens,
thanks for the updated series and the continued work on this. I've
recently starting testing/experimenting with this in the context of
Kernel 4.4 (will try latest Kernel as a next step) and have not found any
issues so far. This is an ongoing effort and I'll provide feedback as I
encounter anything notable.
But I also wanted to use this opportunity to express that from a TI and
TI customer point of view (and probably beyond that) this TEE subsystem
support is seen as an important building block for a number real-world
use cases involving security.
Acked-by: Andreas Dannenberg <dannenberg at ti.com>
Regards,
--
Andreas Dannenberg
Texas Instruments Inc
>
> v7:
> * Rebased on v4.5-rc2
> * Moved the ARM SMC Calling Convention support into a separate patch
> set, which is now merged
>
> v6:
> * Rebased on v4.3-rc7
> * Changed smccc interface to let the compiler marshal most of the
> parameters
> * Added ARCH64 capability for smccc interface
> * Changed the PSCI firmware calls (both arm and arm64) to use the new
> generic smccc interface instead instead of own assembly functions.
> * Move optee DT bindings to below arm/firmware
> * Defines method for OP-TEE driver to call secure world in DT, smc or hvc
> * Exposes implementation id of a TEE driver in sysfs
> to easily spawn corresponding tee-supplicant when device is ready
> * Update OP-TEE Message Protocol to better cope with fragmented physical
> memory
> * Read time directly from OP-TEE driver instead of forwarding the RPC
> request to tee-supplicant
>
> v5:
> * Replaced kref reference counting for the device with a size_t instead as
> the counter is always protected by a mutex
>
> v4:
> * Rebased on 4.1
> * Redesigned the synchronization around entry exit of normal SMC
> * Replaced rwsem on the driver instance with kref and completion since
> rwsem wasn't intended to be used in this way
> * Expanded the TEE_IOCTL_PARAM_ATTR_TYPE_MASK to make room for
> future additional parameter types
> * Documents TEE subsystem and OP-TEE driver
> * Replaced TEE_IOC_CMD with TEE_IOC_OPEN_SESSION, TEE_IOC_INVOKE,
> TEE_IOC_CANCEL and TEE_IOC_CLOSE_SESSION
> * DT bindings in a separate patch
> * Assembly parts moved to arch/arm and arch/arm64 respectively, in a
> separate patch
> * Redefined/clarified the meaning of OPTEE_SMC_SHM_CACHED
> * Removed CMA usage to limit the scope of the patch set
>
> v3:
> * Rebased on 4.1-rc3 (dma_buf_export() API change)
> * A couple of small sparse fixes
> * Documents bindings for OP-TEE driver
> * Updated MAINTAINERS
>
> v2:
> * Replaced the stubbed OP-TEE driver with a real OP-TEE driver
> * Removed most APIs not needed by OP-TEE in current state
> * Update Documentation/ioctl/ioctl-number.txt with correct path to tee.h
> * Rename tee_shm_pool_alloc_cma() to tee_shm_pool_alloc()
> * Moved tee.h into include/uapi/linux/
> * Redefined tee.h IOCTL macros to be directly based on _IOR and friends
> * Removed version info on the API to user space, a data blob which
> can contain an UUID is left for user space to be able to tell which
> protocol to use in TEE_IOC_CMD
> * Changed user space exposed structures to only have types with __ prefix
> * Dropped THIS_MODULE from tee_fops
> * Reworked how the driver is registered and ref counted:
> - moved from using an embedded struct miscdevice to an embedded struct
> device.
> - uses an struct rw_semaphore as synchronization for driver detachment
> - uses alloc/register pattern from TPM
>
> Thanks,
> Jens
>
>
>
> Jens Wiklander (4):
> dt/bindings: add bindings for optee
> tee: generic TEE subsystem
> tee: add OP-TEE driver
> Documentation: tee subsystem and op-tee driver
>
> Documentation/00-INDEX | 2 +
> .../bindings/arm/firmware/linaro,optee-tz.txt | 31 +
> .../devicetree/bindings/vendor-prefixes.txt | 1 +
> Documentation/ioctl/ioctl-number.txt | 1 +
> Documentation/tee.txt | 117 +++
> MAINTAINERS | 13 +
> drivers/Kconfig | 2 +
> drivers/Makefile | 1 +
> drivers/tee/Kconfig | 19 +
> drivers/tee/Makefile | 4 +
> drivers/tee/optee/Kconfig | 8 +
> drivers/tee/optee/Makefile | 5 +
> drivers/tee/optee/call.c | 400 ++++++++++
> drivers/tee/optee/core.c | 522 ++++++++++++
> drivers/tee/optee/optee_msg.h | 423 ++++++++++
> drivers/tee/optee/optee_private.h | 146 ++++
> drivers/tee/optee/optee_smc.h | 418 ++++++++++
> drivers/tee/optee/rpc.c | 322 ++++++++
> drivers/tee/optee/supp.c | 212 +++++
> drivers/tee/tee.c | 873 +++++++++++++++++++++
> drivers/tee/tee_private.h | 80 ++
> drivers/tee/tee_shm.c | 324 ++++++++
> drivers/tee/tee_shm_pool.c | 133 ++++
> include/linux/tee_drv.h | 299 +++++++
> include/uapi/linux/tee.h | 383 +++++++++
> 25 files changed, 4739 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt
> create mode 100644 Documentation/tee.txt
> create mode 100644 drivers/tee/Kconfig
> create mode 100644 drivers/tee/Makefile
> create mode 100644 drivers/tee/optee/Kconfig
> create mode 100644 drivers/tee/optee/Makefile
> create mode 100644 drivers/tee/optee/call.c
> create mode 100644 drivers/tee/optee/core.c
> create mode 100644 drivers/tee/optee/optee_msg.h
> create mode 100644 drivers/tee/optee/optee_private.h
> create mode 100644 drivers/tee/optee/optee_smc.h
> create mode 100644 drivers/tee/optee/rpc.c
> create mode 100644 drivers/tee/optee/supp.c
> create mode 100644 drivers/tee/tee.c
> create mode 100644 drivers/tee/tee_private.h
> create mode 100644 drivers/tee/tee_shm.c
> create mode 100644 drivers/tee/tee_shm_pool.c
> create mode 100644 include/linux/tee_drv.h
> create mode 100644 include/uapi/linux/tee.h
>
> --
> 1.9.1
>
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