| Message ID | 1455210877-15748-5-git-send-email-jens.wiklander@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 02/11/16 09:14, Jens Wiklander wrote: > Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org> > --- > Documentation/00-INDEX | 2 + > Documentation/tee.txt | 117 +++++++++++++++++++++++++++++++++++++++++++++++++ > MAINTAINERS | 1 + > 3 files changed, 120 insertions(+) > create mode 100644 Documentation/tee.txt > 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 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 any more, > + 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 end with '.' > + > +- TEE_IOC_INVOKE invokes a function in a Trusted Application ditto > + > +- TEE_IOC_CANCEL may cancel an ongoing TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE ditto > + > +- TEE_IOC_CLOSE_SESSION closes a session to a Trusted Application ditto > + > +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/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 f13414a..29af59a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9572,6 +9572,7 @@ 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 <andreas.noever@gmail.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org> --- Documentation/00-INDEX | 2 + Documentation/tee.txt | 117 +++++++++++++++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 120 insertions(+) create mode 100644 Documentation/tee.txt