- OP-TEE - lists.trustedfirmware.org

by Jens Wiklander

[BCC all OP-TEE maintainers] Hi OP-TEE maintainers & contributors, OP-TEE v4.1.0 is scheduled to be released on 2024-01-19. So, now is a good time to start testing the master branch on the various platforms and report/fix any bugs. The GitHub pull request for collecting Tested-by tags or any other comments is https://github.com/OP-TEE/optee_os/pull/6574. As usual, we will create a release candidate tag one week before the release date for final testing. In addition to that you can find some additional information related to releases here: https://optee.readthedocs.io/en/latest/general/releases.html Thanks, Jens

8 months, 2 weeks

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Secure interrupt while sending direct response

by Jens Wiklander

Hi all, I'm testing FF-A notifications with OP-TEE and Hafnium. I'm using interrupts from the secure uart as a trigger to set a notification for the normal world. Sometimes when testing I run into: VERBOSE: Secure virtual interrupt not yet serviced by SP 8001. FFA_MSG_SEND_DIRECT_RESP interrupted Hafnium then returns an FFA_ERROR (code -5) as a response to the FFA_MSG_SEND_DIRECT_RESP OP-TEE was just exiting with. After some digging in the code I find a comment at the top of plat_ffa_is_direct_response_interrupted() https://git.trustedfirmware.org/hafnium/hafnium.git/tree/src/arch/aarch64/p… /* * A secure interrupt might trigger while the target SP is currently * running to send a direct response. SPMC would then inject virtual * interrupt to vCPU of target SP and resume it. * However, it is possible that the S-EL1 SP could have its interrupts * masked and hence might not handle the virtual interrupt before * sending direct response message. In such a scenario, SPMC must * return an error with code FFA_INTERRUPTED to inform the S-EL1 SP of * a pending interrupt and allow it to be handled before sending the * direct response. */ The specification doesn't mention this as a valid error code for FFA_MSG_SEND_DIRECT_RESP. Is this something we can expect to be added to the specification or at least something OP-TEE has to be prepared to handle regardless? As far as I can tell there's no way of guaranteeing that Hafnium will not return this error for FFA_MSG_SEND_DIRECT_RESP. Even if we were able to execute the smc instruction with secure interrupts unmasked, what if the interrupt is raised just after the smc instruction has been trapped in Hafnium? It is a bit inconvenient as it means saving the registers passed to the smc instruction to be able to restart the smc instruction with the same arguments. It seems we may need to redesign the exit procedure. It would be nice with an example of how an S-EL1 SP is supposed to exit with FFA_MSG_SEND_DIRECT_RESP. Thoughts? Thanks, Jens

9 months, 2 weeks

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[GIT PULL] Improved TEE shared buffer support for v6.8

by Jens Wiklander

Hello arm-soc maintainers, Please pull this patch to add vmalloc support for shared buffer registration with the secure world. Thanks, Jens The following changes since commit b85ea95d086471afb4ad062012a4d73cd328fa86: Linux 6.7-rc1 (2023-11-12 16:19:07 -0800) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git tags/tee-iov-iter-for-v6.8 for you to fetch changes up to 7bdee41575919773818e525ea19e54eb817770af: tee: Use iov_iter to better support shared buffer registration (2023-12-13 07:23:22 +0100) ---------------------------------------------------------------- TEE: improve shared buffer registration compatibility ---------------------------------------------------------------- Arnaud Pouliquen (1): tee: Use iov_iter to better support shared buffer registration drivers/tee/tee_shm.c | 78 +++++++++++++++++++++++++++------------------------ 1 file changed, 42 insertions(+), 36 deletions(-)

9 months, 2 weeks

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[GIT PULL] OP-TEE cleanup for v6.8

by Jens Wiklander

Hello arm-soc maintainers, Please pull these two small patches for the OP-TEE driver that remove a redundant custom workqueue and add a description of an argument of a optee_handle_rpc(). Note that this pull request is made on top of optee-supplicant-fix-for-v6.7 7269cba53d90 ("tee: optee: Fix supplicant based device enumeration") which was merged into v6.7-rc5, but in turn was based on top of v6.6. I did it like this because the Tested-bys where provided in this context. Thanks, Jens The following changes since commit 7269cba53d906cf257c139d3b3a53ad272176bca: tee: optee: Fix supplicant based device enumeration (2023-11-03 09:27:20 +0100) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git tags/optee-cleanup-for-v6.8 for you to fetch changes up to b19773a1c6c02f5efc35e9f506aeddd2c7d2ac29: optee: add missing description of RPC argument reference (2023-12-11 15:02:12 +0100) ---------------------------------------------------------------- OP-TEE cleanup - Remove a redundant custom workqueue in the OP-TEE driver. - Fix a missing description of an argument to optee_handle_rpc(). ---------------------------------------------------------------- Etienne Carriere (1): optee: add missing description of RPC argument reference Sumit Garg (1): tee: optee: Remove redundant custom workqueue drivers/tee/optee/core.c | 13 ++----------- drivers/tee/optee/optee_private.h | 2 -- drivers/tee/optee/smc_abi.c | 1 + 3 files changed, 3 insertions(+), 13 deletions(-)

9 months, 2 weeks

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[PATCH v5] tee: Use iov_iter to better support shared buffer registration

by Arnaud Pouliquen

Currently it's not possible to register kernel buffers with TEE which are allocated via vmalloc. Use iov_iter and associated helper functions to manage the page registration for all type of memories. Suggested-by: Christoph Hellwig <hch(a)infradead.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen(a)foss.st.com> --- Update from V4 to V5: - replace import_ubuf() by iov_iter_ubuf(), - fix comment in register_shm_helper() function. Update from V3 to V4: - improve commit message, - use import_ubuf() instead of iov_iter_init(), - move shm_get_kernel_pages in register_shm_helper, - put back untagged_addr in register_shm_helper(), - move the comment related to pin pages from shm_get_kernel_pages() to register_shm_helper(). Update from V2 to V3: - break lines longer than 80 columns. Update from V1 to V2: - replace ITER_SOURCE by ITER_DEST flag in tee_shm_register_user_buf(), - replace IS_ERR_OR NULL(shm) by IS_ERR(shm) in tee_shm_register_user_buf(). V1: The support of buffer registration allocated with vmalloc is no more available since c83900393aa1 ("tee: Remove vmalloc page support"). This patch is an alternative to a revert and resulted from a discussion with Christopher Hellwig [1]. This patch has been tested using xtest tool in optee qemu environment [2] and using the series related to the remoteproc tee that should be proposed soon [3]. References: [1] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39f… [2] https://optee.readthedocs.io/en/latest/building/devices/qemu.html#build-ins… [3] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39f… --- drivers/tee/tee_shm.c | 78 +++++++++++++++++++++++-------------------- 1 file changed, 42 insertions(+), 36 deletions(-) diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index 673cf0359494..731d9028b67f 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -22,23 +22,12 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count) put_page(pages[n]); } -static int shm_get_kernel_pages(unsigned long start, size_t page_count, - struct page **pages) +static void shm_get_kernel_pages(struct page **pages, size_t page_count) { - struct page *page; size_t n; - if (WARN_ON_ONCE(is_vmalloc_addr((void *)start) || - is_kmap_addr((void *)start))) - return -EINVAL; - - page = virt_to_page((void *)start); - for (n = 0; n < page_count; n++) { - pages[n] = page + n; + for (n = 0; n < page_count; n++) get_page(pages[n]); - } - - return page_count; } static void release_registered_pages(struct tee_shm *shm) @@ -214,13 +203,14 @@ struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size) EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_buf); static struct tee_shm * -register_shm_helper(struct tee_context *ctx, unsigned long addr, - size_t length, u32 flags, int id) +register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, + int id) { struct tee_device *teedev = ctx->teedev; struct tee_shm *shm; - unsigned long start; - size_t num_pages; + unsigned long start, addr; + size_t num_pages, off; + ssize_t len; void *ret; int rc; @@ -245,31 +235,38 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr, shm->flags = flags; shm->ctx = ctx; shm->id = id; - addr = untagged_addr(addr); + addr = untagged_addr((unsigned long)iter_iov_addr(iter)); start = rounddown(addr, PAGE_SIZE); - shm->offset = addr - start; - shm->size = length; - num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE; + num_pages = iov_iter_npages(iter, INT_MAX); + if (!num_pages) { + ret = ERR_PTR(-ENOMEM); + goto err_ctx_put; + } + shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL); if (!shm->pages) { ret = ERR_PTR(-ENOMEM); goto err_free_shm; } - if (flags & TEE_SHM_USER_MAPPED) - rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE, - shm->pages); - else - rc = shm_get_kernel_pages(start, num_pages, shm->pages); - if (rc > 0) - shm->num_pages = rc; - if (rc != num_pages) { - if (rc >= 0) - rc = -ENOMEM; - ret = ERR_PTR(rc); - goto err_put_shm_pages; + len = iov_iter_extract_pages(iter, &shm->pages, LONG_MAX, num_pages, 0, + &off); + if (unlikely(len <= 0)) { + ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM); + goto err_free_shm_pages; } + /* + * iov_iter_extract_kvec_pages does not get reference on the pages, + * get a reference on them. + */ + if (iov_iter_is_kvec(iter)) + shm_get_kernel_pages(shm->pages, num_pages); + + shm->offset = off; + shm->size = len; + shm->num_pages = num_pages; + rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages, shm->num_pages, start); if (rc) { @@ -279,10 +276,11 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr, return shm; err_put_shm_pages: - if (flags & TEE_SHM_USER_MAPPED) + if (!iov_iter_is_kvec(iter)) unpin_user_pages(shm->pages, shm->num_pages); else shm_put_kernel_pages(shm->pages, shm->num_pages); +err_free_shm_pages: kfree(shm->pages); err_free_shm: kfree(shm); @@ -307,6 +305,7 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, u32 flags = TEE_SHM_USER_MAPPED | TEE_SHM_DYNAMIC; struct tee_device *teedev = ctx->teedev; struct tee_shm *shm; + struct iov_iter iter; void *ret; int id; @@ -319,7 +318,8 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, if (id < 0) return ERR_PTR(id); - shm = register_shm_helper(ctx, addr, length, flags, id); + iov_iter_ubuf(&iter, ITER_DEST, (void __user *)addr, length); + shm = register_shm_helper(ctx, &iter, flags, id); if (IS_ERR(shm)) { mutex_lock(&teedev->mutex); idr_remove(&teedev->idr, id); @@ -352,8 +352,14 @@ struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx, void *addr, size_t length) { u32 flags = TEE_SHM_DYNAMIC; + struct kvec kvec; + struct iov_iter iter; + + kvec.iov_base = addr; + kvec.iov_len = length; + iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, length); - return register_shm_helper(ctx, (unsigned long)addr, length, flags, -1); + return register_shm_helper(ctx, &iter, flags, -1); } EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf); -- 2.25.1

9 months, 3 weeks

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[PATCH v9 0/6] introduce tee-based EFI Runtime Variable Service

by Masahisa Kojima

This series introduces the tee based EFI Runtime Variable Service. The eMMC device is typically owned by the non-secure world(linux in this case). There is an existing solution utilizing eMMC RPMB partition for EFI Variables, it is implemented by interacting with OP-TEE, StandaloneMM(as EFI Variable Service Pseudo TA), eMMC driver and tee-supplicant. The last piece is the tee-based variable access driver to interact with OP-TEE and StandaloneMM. Changelog: v8 -> v9 - patch #6 "tee: optee: restore efivars ops when tee-supplicant stops" is newly added - remove !EFI_VARS_PSTORE Kconfig dependency, we have added a non-blocking set_variable and it just returns EFI_UNSUPPORTED. - remove obvious comments v7 -> v8 Only patch #3 "efi: Add tee-based EFI variable driver" is updated. - fix typos - refactor error handling, direct return if applicable - use devm_add_action_or_reset() for closing of tee context/session - remove obvious comment v6 -> v7 Patch #1-#4 are not updated. Patch #5 is added into this series, original patch is here: https://lore.kernel.org/all/20230609094532.562934-1-ilias.apalodimas@linaro… There are two issues in the v6 series and v7 series addresses those. 1) efivar ops is not restored when the tee-supplicant daemon terminates. -> As the following patch says, user must remove the device before terminating tee-supplicant daemon. https://lore.kernel.org/all/20230728134832.326467-1-sumit.garg@linaro.org/ 2) cause panic when someone remounts the efivarfs as RW even if SetVariable is not supported -> The fifth patch addresses this issue. "[PATCH v7 5/5] efivarfs: force RO when remounting if SetVariable is not supported" v5 -> v6 - new patch #4 is added in this series, #1-#3 patches are unchanged. automatically update super block flag when the efivarops support SetVariable runtime service, so that user does not need to manually remount the efivarfs as RW. v4 -> v5 - rebase to efi-next based on v6.4-rc1 - set generic_ops.query_variable_info, it works as expected as follows. $ df -h /sys/firmware/efi/efivars/ Filesystem Size Used Avail Use% Mounted on efivarfs 16K 1.3K 15K 8% /sys/firmware/efi/efivars v3 -> v4: - replace the reference from EDK2 to PI Specification - remove EDK2 source code reference comments - prepare nonblocking variant of set_variable, it just returns EFI_UNSUPPORTED - remove redundant buffer size check - argument name change in mm_communicate - function interface changes in setup_mm_hdr to remove (void **) cast v2 -> v3: - add CONFIG_EFI dependency to TEE_STMM_EFI - add missing return code check for tee_client_invoke_func() - directly call efivars_register/unregister from tee_stmm_efi.c rfc v1 -> v2: - split patch into three patches, one for drivers/tee, one for include/linux/efi.h, and one for the driver/firmware/efi/stmm - context/session management into probe() and remove() same as other tee client driver - StMM variable driver is moved from driver/tee/optee to driver/firmware/efi - use "tee" prefix instead of "optee" in driver/firmware/efi/stmm/tee_stmm_efi.c, this file does not contain op-tee specific code, abstracted by tee layer and StMM variable driver will work on other tee implementation. - PTA_STMM_CMD_COMMUNICATE -> PTA_STMM_CMD_COMMUNICATE - implement query_variable_store() but currently not used - no use of TEEC_SUCCESS, it is defined in driver/tee/optee/optee_private.h. Other tee client drivers use 0 instead of using TEEC_SUCCESS - remove TEEC_ERROR_EXCESS_DATA status, it is referred just to output error message Ilias Apalodimas (1): efivarfs: force RO when remounting if SetVariable is not supported Masahisa Kojima (5): efi: expose efivar generic ops register function efi: Add EFI_ACCESS_DENIED status code efi: Add tee-based EFI variable driver efivarfs: automatically update super block flag tee: optee: restore efivars ops when tee-supplicant stops drivers/firmware/efi/Kconfig | 15 + drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/efi.c | 18 + drivers/firmware/efi/stmm/mm_communication.h | 236 +++++++ drivers/firmware/efi/stmm/tee_stmm_efi.c | 617 +++++++++++++++++++ drivers/firmware/efi/vars.c | 8 + drivers/tee/optee/supp.c | 4 + fs/efivarfs/super.c | 45 ++ include/linux/efi.h | 13 + 9 files changed, 957 insertions(+) create mode 100644 drivers/firmware/efi/stmm/mm_communication.h create mode 100644 drivers/firmware/efi/stmm/tee_stmm_efi.c base-commit: b691118f2c44d16b84fc65b8147b33620eb18cac -- 2.30.2

9 months, 3 weeks

4
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[GIT PULL] OP-TEE kernel private shared memory optimizations for 6.8

by Jens Wiklander

Hello arm-soc maintainers, Please pull these two patches that optmize how the OP-TEE driver private shared memory allocated as dynamic shared memory. Thanks, Jens The following changes since commit b85ea95d086471afb4ad062012a4d73cd328fa86: Linux 6.7-rc1 (2023-11-12 16:19:07 -0800) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git tags/kern-priv-shm-for-v6.8 for you to fetch changes up to 225a36b96359aceaa9a6399f2dff99627397e637: optee: allocate shared memory with alloc_pages_exact() (2023-12-04 14:48:42 +0100) ---------------------------------------------------------------- OP-TEE kernel private shared memory optimizations Optimize OP-TEE driver private shared memory allocated as dynamic shared memory. Both to handle larger than one page allocations and for more efficient memory usage. ---------------------------------------------------------------- Jens Wiklander (2): optee: add page list to kernel private shared memory optee: allocate shared memory with alloc_pages_exact() drivers/tee/optee/core.c | 44 +++++++++++++++++++++++--------------------- drivers/tee/optee/smc_abi.c | 45 +++++++++++++++++++++------------------------ 2 files changed, 44 insertions(+), 45 deletions(-)

9 months, 3 weeks

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[GIT PULL] OP-TEE FF-A asynchronous notifications for 6.8

by Jens Wiklander

Hello arm-soc maintainers, Please pull these patches that enables asynchronous notifications in OP-TEE FF-A driver. This pull request is on top of the "system_thread_for_v6.8" pull request to avoid a merge conflict. Thanks, Jens The following changes since commit 4b391c9c37646f25118355f414b9e6d9fefe782f: firmware: arm_scmi: optee: use optee system invocation (2023-11-17 15:48:03 +0100) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git tags/ffa-notif-for-v6.8 for you to fetch changes up to d0476a59de064205f4aaa8f7c6d6f32bc28a44d4: optee: ffa_abi: add asynchronous notifications (2023-11-17 15:55:41 +0100) ---------------------------------------------------------------- OP-TEE: asynchronous notifications with FF-A Add support for asynchronous notifications in the OP-TEE FF-A driver. This is the FF-A counterpart to the asynchronous notifications already available in the OP-TEE SMC ABI. ---------------------------------------------------------------- Jens Wiklander (2): optee: provide optee_do_bottom_half() as a common function optee: ffa_abi: add asynchronous notifications drivers/tee/optee/call.c | 31 ++++++++++++- drivers/tee/optee/ffa_abi.c | 93 +++++++++++++++++++++++++++++++++++++-- drivers/tee/optee/optee_ffa.h | 28 ++++++++++-- drivers/tee/optee/optee_private.h | 9 +++- drivers/tee/optee/smc_abi.c | 36 ++------------- 5 files changed, 155 insertions(+), 42 deletions(-)

9 months, 3 weeks

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[GIT PULL] OP-TEE reserved system thread for 6.8

by Jens Wiklander

Hello arm-soc maintainers, Please pull these patches that enables SCMI with OP-TEE transport to to reserve a thread in the secure world to guarentee that requests will not have to wait for a thread to become available. Thanks, Jens The following changes since commit b85ea95d086471afb4ad062012a4d73cd328fa86: Linux 6.7-rc1 (2023-11-12 16:19:07 -0800) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git tags/system-thread-for-v6.8 for you to fetch changes up to 4b391c9c37646f25118355f414b9e6d9fefe782f: firmware: arm_scmi: optee: use optee system invocation (2023-11-17 15:48:03 +0100) ---------------------------------------------------------------- OP-TEE add reserved system thread Add support for a reserved system thread in the SMC-ABI of the OP-TEE driver. SCMI with OP-TEE transport uses this to guarantee that it will always have a thread available in the secure world. ---------------------------------------------------------------- Etienne Carriere (4): tee: optee: system thread call property tee: system session tee: optee: support tracking system threads firmware: arm_scmi: optee: use optee system invocation drivers/firmware/arm_scmi/optee.c | 4 ++ drivers/tee/optee/call.c | 130 ++++++++++++++++++++++++++++++++++++-- drivers/tee/optee/core.c | 5 +- drivers/tee/optee/ffa_abi.c | 14 ++-- drivers/tee/optee/optee_private.h | 29 ++++++++- drivers/tee/optee/smc_abi.c | 32 +++++++--- drivers/tee/tee_core.c | 8 +++ include/linux/tee_drv.h | 16 +++++ 8 files changed, 211 insertions(+), 27 deletions(-)

9 months, 3 weeks

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[PATCH v3] Documentation: Destage TEE subsystem documentation

by Sumit Garg

Add a separate documentation directory for TEE subsystem since it is a standalone subsystem which already offers devices consumed by multiple different subsystem drivers. Split overall TEE subsystem documentation modularly where: - The userspace API has been moved to Documentation/userspace-api/tee.rst. - The driver API has been moved to Documentation/driver-api/tee.rst. - The first module covers the overview of TEE subsystem. - The further modules are dedicated to different TEE implementations like: - OP-TEE - AMD-TEE - and so on for future TEE implementation support. Acked-by: Rijo Thomas <Rijo-john.Thomas(a)amd.com> Acked-by: Jens Wiklander <jens.wiklander(a)linaro.org> Signed-off-by: Sumit Garg <sumit.garg(a)linaro.org> --- Changes in v3: - Rebased to docs-next - Fixed dangling references to Documentation/staging/tee.rst. - Applied tags. Changes in v2: - Move userspace API to Documentation/userspace-api/tee.rst. - Move driver API to Documentation/driver-api/tee.rst. Documentation/driver-api/index.rst | 1 + Documentation/driver-api/tee.rst | 66 ++++ .../security/keys/trusted-encrypted.rst | 2 +- Documentation/staging/index.rst | 1 - Documentation/staging/tee.rst | 364 ------------------ Documentation/subsystem-apis.rst | 1 + Documentation/tee/amd-tee.rst | 90 +++++ Documentation/tee/index.rst | 19 + Documentation/tee/op-tee.rst | 166 ++++++++ Documentation/tee/tee.rst | 22 ++ Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/tee.rst | 39 ++ MAINTAINERS | 4 +- drivers/tee/optee/Kconfig | 2 +- 14 files changed, 410 insertions(+), 368 deletions(-) create mode 100644 Documentation/driver-api/tee.rst delete mode 100644 Documentation/staging/tee.rst create mode 100644 Documentation/tee/amd-tee.rst create mode 100644 Documentation/tee/index.rst create mode 100644 Documentation/tee/op-tee.rst create mode 100644 Documentation/tee/tee.rst create mode 100644 Documentation/userspace-api/tee.rst diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index 48bd9921d937..9511db303446 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -112,6 +112,7 @@ available subsections can be seen below. hte/index wmi dpll + tee .. only:: subproject and html diff --git a/Documentation/driver-api/tee.rst b/Documentation/driver-api/tee.rst new file mode 100644 index 000000000000..5eaeb8103988 --- /dev/null +++ b/Documentation/driver-api/tee.rst @@ -0,0 +1,66 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +TEE (Trusted Execution Environment) driver API +=============================================== + +Kernel provides a TEE bus infrastructure where a Trusted Application is +represented as a device identified via Universally Unique Identifier (UUID) and +client drivers register a table of supported device UUIDs. + +TEE bus infrastructure registers following APIs: + +match(): + iterates over the client driver UUID table to find a corresponding + match for device UUID. If a match is found, then this particular device is + probed via corresponding probe API registered by the client driver. This + process happens whenever a device or a client driver is registered with TEE + bus. + +uevent(): + notifies user-space (udev) whenever a new device is registered on + TEE bus for auto-loading of modularized client drivers. + +TEE bus device enumeration is specific to underlying TEE implementation, so it +is left open for TEE drivers to provide corresponding implementation. + +Then TEE client driver can talk to a matched Trusted Application using APIs +listed in include/linux/tee_drv.h. + +TEE client driver example +------------------------- + +Suppose a TEE client driver needs to communicate with a Trusted Application +having UUID: ``ac6a4085-0e82-4c33-bf98-8eb8e118b6c2``, so driver registration +snippet would look like:: + + static const struct tee_client_device_id client_id_table[] = { + {UUID_INIT(0xac6a4085, 0x0e82, 0x4c33, + 0xbf, 0x98, 0x8e, 0xb8, 0xe1, 0x18, 0xb6, 0xc2)}, + {} + }; + + MODULE_DEVICE_TABLE(tee, client_id_table); + + static struct tee_client_driver client_driver = { + .id_table = client_id_table, + .driver = { + .name = DRIVER_NAME, + .bus = &tee_bus_type, + .probe = client_probe, + .remove = client_remove, + }, + }; + + static int __init client_init(void) + { + return driver_register(&client_driver.driver); + } + + static void __exit client_exit(void) + { + driver_unregister(&client_driver.driver); + } + + module_init(client_init); + module_exit(client_exit); diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst index 9bc9db8ec651..e989b9802f92 100644 --- a/Documentation/security/keys/trusted-encrypted.rst +++ b/Documentation/security/keys/trusted-encrypted.rst @@ -88,7 +88,7 @@ safe. (2) TEE TEEs have well-documented, standardized client interface and APIs. For - more details refer to ``Documentation/staging/tee.rst``. + more details refer to ``Documentation/driver-api/tee.rst``. (3) CAAM diff --git a/Documentation/staging/index.rst b/Documentation/staging/index.rst index ded8254bc0d7..71592f3ce89b 100644 --- a/Documentation/staging/index.rst +++ b/Documentation/staging/index.rst @@ -12,5 +12,4 @@ Unsorted Documentation rpmsg speculation static-keys - tee xz diff --git a/Documentation/staging/tee.rst b/Documentation/staging/tee.rst deleted file mode 100644 index 22baa077a3b9..000000000000 --- a/Documentation/staging/tee.rst +++ /dev/null @@ -1,364 +0,0 @@ -============= -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 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 - 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. - -The TEE kernel interface -======================== - -Kernel provides a TEE bus infrastructure where a Trusted Application is -represented as a device identified via Universally Unique Identifier (UUID) and -client drivers register a table of supported device UUIDs. - -TEE bus infrastructure registers following APIs: - -match(): - iterates over the client driver UUID table to find a corresponding - match for device UUID. If a match is found, then this particular device is - probed via corresponding probe API registered by the client driver. This - process happens whenever a device or a client driver is registered with TEE - bus. - -uevent(): - notifies user-space (udev) whenever a new device is registered on - TEE bus for auto-loading of modularized client drivers. - -TEE bus device enumeration is specific to underlying TEE implementation, so it -is left open for TEE drivers to provide corresponding implementation. - -Then TEE client driver can talk to a matched Trusted Application using APIs -listed in include/linux/tee_drv.h. - -TEE client driver example -------------------------- - -Suppose a TEE client driver needs to communicate with a Trusted Application -having UUID: ``ac6a4085-0e82-4c33-bf98-8eb8e118b6c2``, so driver registration -snippet would look like:: - - static const struct tee_client_device_id client_id_table[] = { - {UUID_INIT(0xac6a4085, 0x0e82, 0x4c33, - 0xbf, 0x98, 0x8e, 0xb8, 0xe1, 0x18, 0xb6, 0xc2)}, - {} - }; - - MODULE_DEVICE_TABLE(tee, client_id_table); - - static struct tee_client_driver client_driver = { - .id_table = client_id_table, - .driver = { - .name = DRIVER_NAME, - .bus = &tee_bus_type, - .probe = client_probe, - .remove = client_remove, - }, - }; - - static int __init client_init(void) - { - return driver_register(&client_driver.driver); - } - - static void __exit client_exit(void) - { - driver_unregister(&client_driver.driver); - } - - module_init(client_init); - module_exit(client_exit); - -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. - -OP-TEE device enumeration -------------------------- - -OP-TEE provides a pseudo Trusted Application: drivers/tee/optee/device.c in -order to support device enumeration. In other words, OP-TEE driver invokes this -application to retrieve a list of Trusted Applications which can be registered -as devices on the TEE bus. - -OP-TEE notifications --------------------- - -There are two kinds of notifications that secure world can use to make -normal world aware of some event. - -1. Synchronous notifications delivered with ``OPTEE_RPC_CMD_NOTIFICATION`` - using the ``OPTEE_RPC_NOTIFICATION_SEND`` parameter. -2. Asynchronous notifications delivered with a combination of a non-secure - edge-triggered interrupt and a fast call from the non-secure interrupt - handler. - -Synchronous notifications are limited by depending on RPC for delivery, -this is only usable when secure world is entered with a yielding call via -``OPTEE_SMC_CALL_WITH_ARG``. This excludes such notifications from secure -world interrupt handlers. - -An asynchronous notification is delivered via a non-secure edge-triggered -interrupt to an interrupt handler registered in the OP-TEE driver. The -actual notification value are retrieved with the fast call -``OPTEE_SMC_GET_ASYNC_NOTIF_VALUE``. Note that one interrupt can represent -multiple notifications. - -One notification value ``OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF`` has a -special meaning. When this value is received it means that normal world is -supposed to make a yielding call ``OPTEE_MSG_CMD_DO_BOTTOM_HALF``. This -call is done from the thread assisting the interrupt handler. This is a -building block for OP-TEE OS in secure world to implement the top half and -bottom half style of device drivers. - -OPTEE_INSECURE_LOAD_IMAGE Kconfig option ----------------------------------------- - -The OPTEE_INSECURE_LOAD_IMAGE Kconfig option enables the ability to load the -BL32 OP-TEE image from the kernel after the kernel boots, rather than loading -it from the firmware before the kernel boots. This also requires enabling the -corresponding option in Trusted Firmware for Arm. The Trusted Firmware for Arm -documentation [8] explains the security threat associated with enabling this as -well as mitigations at the firmware and platform level. - -There are additional attack vectors/mitigations for the kernel that should be -addressed when using this option. - -1. Boot chain security. - - * Attack vector: Replace the OP-TEE OS image in the rootfs to gain control of - the system. - - * Mitigation: There must be boot chain security that verifies the kernel and - rootfs, otherwise an attacker can modify the loaded OP-TEE binary by - modifying it in the rootfs. - -2. Alternate boot modes. - - * Attack vector: Using an alternate boot mode (i.e. recovery mode), the - OP-TEE driver isn't loaded, leaving the SMC hole open. - - * Mitigation: If there are alternate methods of booting the device, such as a - recovery mode, it should be ensured that the same mitigations are applied - in that mode. - -3. Attacks prior to SMC invocation. - - * Attack vector: Code that is executed prior to issuing the SMC call to load - OP-TEE can be exploited to then load an alternate OS image. - - * Mitigation: The OP-TEE driver must be loaded before any potential attack - vectors are opened up. This should include mounting of any modifiable - filesystems, opening of network ports or communicating with external - devices (e.g. USB). - -4. Blocking SMC call to load OP-TEE. - - * Attack vector: Prevent the driver from being probed, so the SMC call to - load OP-TEE isn't executed when desired, leaving it open to being executed - later and loading a modified OS. - - * Mitigation: It is recommended to build the OP-TEE driver as builtin driver - rather than as a module to prevent exploits that may cause the module to - not be loaded. - -AMD-TEE driver -============== - -The AMD-TEE driver handles the communication with AMD's TEE environment. The -TEE environment is provided by AMD Secure Processor. - -The AMD Secure Processor (formerly called Platform Security Processor or PSP) -is a dedicated processor that features ARM TrustZone technology, along with a -software-based Trusted Execution Environment (TEE) designed to enable -third-party Trusted Applications. This feature is currently enabled only for -APUs. - -The following picture shows a high level overview of AMD-TEE:: - - | - x86 | - | - User space (Kernel space) | AMD Secure Processor (PSP) - ~~~~~~~~~~ ~~~~~~~~~~~~~~ | ~~~~~~~~~~~~~~~~~~~~~~~~~~ - | - +--------+ | +-------------+ - | Client | | | Trusted | - +--------+ | | Application | - /\ | +-------------+ - || | /\ - || | || - || | \/ - || | +----------+ - || | | TEE | - || | | Internal | - \/ | | API | - +---------+ +-----------+---------+ +----------+ - | TEE | | TEE | AMD-TEE | | AMD-TEE | - | Client | | subsystem | driver | | Trusted | - | API | | | | | OS | - +---------+-----------+----+------+---------+---------+----------+ - | Generic TEE API | | ASP | Mailbox | - | IOCTL (TEE_IOC_*) | | driver | Register Protocol | - +--------------------------+ +---------+--------------------+ - -At the lowest level (in x86), the AMD Secure Processor (ASP) driver uses the -CPU to PSP mailbox register to submit commands to the PSP. The format of the -command buffer is opaque to the ASP driver. It's role is to submit commands to -the secure processor and return results to AMD-TEE driver. The interface -between AMD-TEE driver and AMD Secure Processor driver can be found in [6]. - -The AMD-TEE driver packages the command buffer payload for processing in TEE. -The command buffer format for the different TEE commands can be found in [7]. - -The TEE commands supported by AMD-TEE Trusted OS are: - -* TEE_CMD_ID_LOAD_TA - loads a Trusted Application (TA) binary into - TEE environment. -* TEE_CMD_ID_UNLOAD_TA - unloads TA binary from TEE environment. -* TEE_CMD_ID_OPEN_SESSION - opens a session with a loaded TA. -* TEE_CMD_ID_CLOSE_SESSION - closes session with loaded TA -* TEE_CMD_ID_INVOKE_CMD - invokes a command with loaded TA -* TEE_CMD_ID_MAP_SHARED_MEM - maps shared memory -* TEE_CMD_ID_UNMAP_SHARED_MEM - unmaps shared memory - -AMD-TEE Trusted OS is the firmware running on AMD Secure Processor. - -The AMD-TEE driver registers itself with TEE subsystem and implements the -following driver function callbacks: - -* get_version - returns the driver implementation id and capability. -* open - sets up the driver context data structure. -* release - frees up driver resources. -* open_session - loads the TA binary and opens session with loaded TA. -* close_session - closes session with loaded TA and unloads it. -* invoke_func - invokes a command with loaded TA. - -cancel_req driver callback is not supported by AMD-TEE. - -The GlobalPlatform TEE Client API [5] can be used by the user space (client) to -talk to AMD's TEE. AMD's TEE provides a secure environment for loading, opening -a session, invoking commands and closing session with TA. - -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. - -[6] include/linux/psp-tee.h - -[7] drivers/tee/amdtee/amdtee_if.h - -[8] https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… diff --git a/Documentation/subsystem-apis.rst b/Documentation/subsystem-apis.rst index 930dc23998a0..2d353fb8ea26 100644 --- a/Documentation/subsystem-apis.rst +++ b/Documentation/subsystem-apis.rst @@ -86,3 +86,4 @@ Storage interfaces misc-devices/index peci/index wmi/index + tee/index diff --git a/Documentation/tee/amd-tee.rst b/Documentation/tee/amd-tee.rst new file mode 100644 index 000000000000..51500fde7038 --- /dev/null +++ b/Documentation/tee/amd-tee.rst @@ -0,0 +1,90 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================================= +AMD-TEE (AMD's Trusted Execution Environment) +============================================= + +The AMD-TEE driver handles the communication with AMD's TEE environment. The +TEE environment is provided by AMD Secure Processor. + +The AMD Secure Processor (formerly called Platform Security Processor or PSP) +is a dedicated processor that features ARM TrustZone technology, along with a +software-based Trusted Execution Environment (TEE) designed to enable +third-party Trusted Applications. This feature is currently enabled only for +APUs. + +The following picture shows a high level overview of AMD-TEE:: + + | + x86 | + | + User space (Kernel space) | AMD Secure Processor (PSP) + ~~~~~~~~~~ ~~~~~~~~~~~~~~ | ~~~~~~~~~~~~~~~~~~~~~~~~~~ + | + +--------+ | +-------------+ + | Client | | | Trusted | + +--------+ | | Application | + /\ | +-------------+ + || | /\ + || | || + || | \/ + || | +----------+ + || | | TEE | + || | | Internal | + \/ | | API | + +---------+ +-----------+---------+ +----------+ + | TEE | | TEE | AMD-TEE | | AMD-TEE | + | Client | | subsystem | driver | | Trusted | + | API | | | | | OS | + +---------+-----------+----+------+---------+---------+----------+ + | Generic TEE API | | ASP | Mailbox | + | IOCTL (TEE_IOC_*) | | driver | Register Protocol | + +--------------------------+ +---------+--------------------+ + +At the lowest level (in x86), the AMD Secure Processor (ASP) driver uses the +CPU to PSP mailbox register to submit commands to the PSP. The format of the +command buffer is opaque to the ASP driver. It's role is to submit commands to +the secure processor and return results to AMD-TEE driver. The interface +between AMD-TEE driver and AMD Secure Processor driver can be found in [1]. + +The AMD-TEE driver packages the command buffer payload for processing in TEE. +The command buffer format for the different TEE commands can be found in [2]. + +The TEE commands supported by AMD-TEE Trusted OS are: + +* TEE_CMD_ID_LOAD_TA - loads a Trusted Application (TA) binary into + TEE environment. +* TEE_CMD_ID_UNLOAD_TA - unloads TA binary from TEE environment. +* TEE_CMD_ID_OPEN_SESSION - opens a session with a loaded TA. +* TEE_CMD_ID_CLOSE_SESSION - closes session with loaded TA +* TEE_CMD_ID_INVOKE_CMD - invokes a command with loaded TA +* TEE_CMD_ID_MAP_SHARED_MEM - maps shared memory +* TEE_CMD_ID_UNMAP_SHARED_MEM - unmaps shared memory + +AMD-TEE Trusted OS is the firmware running on AMD Secure Processor. + +The AMD-TEE driver registers itself with TEE subsystem and implements the +following driver function callbacks: + +* get_version - returns the driver implementation id and capability. +* open - sets up the driver context data structure. +* release - frees up driver resources. +* open_session - loads the TA binary and opens session with loaded TA. +* close_session - closes session with loaded TA and unloads it. +* invoke_func - invokes a command with loaded TA. + +cancel_req driver callback is not supported by AMD-TEE. + +The GlobalPlatform TEE Client API [3] can be used by the user space (client) to +talk to AMD's TEE. AMD's TEE provides a secure environment for loading, opening +a session, invoking commands and closing session with TA. + +References +========== + +[1] include/linux/psp-tee.h + +[2] drivers/tee/amdtee/amdtee_if.h + +[3] http://www.globalplatform.org/specificationsdevice.asp look for + "TEE Client API Specification v1.0" and click download. diff --git a/Documentation/tee/index.rst b/Documentation/tee/index.rst new file mode 100644 index 000000000000..a23bd08847e5 --- /dev/null +++ b/Documentation/tee/index.rst @@ -0,0 +1,19 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============= +TEE Subsystem +============= + +.. toctree:: + :maxdepth: 1 + + tee + op-tee + amd-tee + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/tee/op-tee.rst b/Documentation/tee/op-tee.rst new file mode 100644 index 000000000000..b0ac097d5547 --- /dev/null +++ b/Documentation/tee/op-tee.rst @@ -0,0 +1,166 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================================================== +OP-TEE (Open Portable Trusted Execution Environment) +==================================================== + +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. + +OP-TEE device enumeration +------------------------- + +OP-TEE provides a pseudo Trusted Application: drivers/tee/optee/device.c in +order to support device enumeration. In other words, OP-TEE driver invokes this +application to retrieve a list of Trusted Applications which can be registered +as devices on the TEE bus. + +OP-TEE notifications +-------------------- + +There are two kinds of notifications that secure world can use to make +normal world aware of some event. + +1. Synchronous notifications delivered with ``OPTEE_RPC_CMD_NOTIFICATION`` + using the ``OPTEE_RPC_NOTIFICATION_SEND`` parameter. +2. Asynchronous notifications delivered with a combination of a non-secure + edge-triggered interrupt and a fast call from the non-secure interrupt + handler. + +Synchronous notifications are limited by depending on RPC for delivery, +this is only usable when secure world is entered with a yielding call via +``OPTEE_SMC_CALL_WITH_ARG``. This excludes such notifications from secure +world interrupt handlers. + +An asynchronous notification is delivered via a non-secure edge-triggered +interrupt to an interrupt handler registered in the OP-TEE driver. The +actual notification value are retrieved with the fast call +``OPTEE_SMC_GET_ASYNC_NOTIF_VALUE``. Note that one interrupt can represent +multiple notifications. + +One notification value ``OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF`` has a +special meaning. When this value is received it means that normal world is +supposed to make a yielding call ``OPTEE_MSG_CMD_DO_BOTTOM_HALF``. This +call is done from the thread assisting the interrupt handler. This is a +building block for OP-TEE OS in secure world to implement the top half and +bottom half style of device drivers. + +OPTEE_INSECURE_LOAD_IMAGE Kconfig option +---------------------------------------- + +The OPTEE_INSECURE_LOAD_IMAGE Kconfig option enables the ability to load the +BL32 OP-TEE image from the kernel after the kernel boots, rather than loading +it from the firmware before the kernel boots. This also requires enabling the +corresponding option in Trusted Firmware for Arm. The Trusted Firmware for Arm +documentation [6] explains the security threat associated with enabling this as +well as mitigations at the firmware and platform level. + +There are additional attack vectors/mitigations for the kernel that should be +addressed when using this option. + +1. Boot chain security. + + * Attack vector: Replace the OP-TEE OS image in the rootfs to gain control of + the system. + + * Mitigation: There must be boot chain security that verifies the kernel and + rootfs, otherwise an attacker can modify the loaded OP-TEE binary by + modifying it in the rootfs. + +2. Alternate boot modes. + + * Attack vector: Using an alternate boot mode (i.e. recovery mode), the + OP-TEE driver isn't loaded, leaving the SMC hole open. + + * Mitigation: If there are alternate methods of booting the device, such as a + recovery mode, it should be ensured that the same mitigations are applied + in that mode. + +3. Attacks prior to SMC invocation. + + * Attack vector: Code that is executed prior to issuing the SMC call to load + OP-TEE can be exploited to then load an alternate OS image. + + * Mitigation: The OP-TEE driver must be loaded before any potential attack + vectors are opened up. This should include mounting of any modifiable + filesystems, opening of network ports or communicating with external + devices (e.g. USB). + +4. Blocking SMC call to load OP-TEE. + + * Attack vector: Prevent the driver from being probed, so the SMC call to + load OP-TEE isn't executed when desired, leaving it open to being executed + later and loading a modified OS. + + * Mitigation: It is recommended to build the OP-TEE driver as builtin driver + rather than as a module to prevent exploits that may cause the module to + not be loaded. + +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. + +[6] https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… diff --git a/Documentation/tee/tee.rst b/Documentation/tee/tee.rst new file mode 100644 index 000000000000..fd9f8c4ff63d --- /dev/null +++ b/Documentation/tee/tee.rst @@ -0,0 +1,22 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================== +TEE (Trusted Execution Environment) +=================================== + +This document describes the TEE subsystem in Linux. + +Overview +======== + +A TEE 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 diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index bf8d2ee01580..93174ffc7350 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -30,6 +30,7 @@ place where this information is gathered. sysfs-platform_profile vduse futex2 + tee .. only:: subproject and html diff --git a/Documentation/userspace-api/tee.rst b/Documentation/userspace-api/tee.rst new file mode 100644 index 000000000000..e2368dbc3451 --- /dev/null +++ b/Documentation/userspace-api/tee.rst @@ -0,0 +1,39 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. tee: + +================================================== +TEE (Trusted Execution Environment) Userspace API +================================================== + +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 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 + 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. diff --git a/MAINTAINERS b/MAINTAINERS index 48fc02d3a1d1..6024d1d5ebf8 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -21351,7 +21351,9 @@ M: Jens Wiklander <jens.wiklander(a)linaro.org> R: Sumit Garg <sumit.garg(a)linaro.org> L: op-tee(a)lists.trustedfirmware.org S: Maintained -F: Documentation/staging/tee.rst +F: Documentation/driver-api/tee.rst +F: Documentation/tee/ +F: Documentation/userspace-api/tee.rst F: drivers/tee/ F: include/linux/tee_drv.h F: include/uapi/linux/tee.h diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig index 70898bbd5809..976928641aa6 100644 --- a/drivers/tee/optee/Kconfig +++ b/drivers/tee/optee/Kconfig @@ -23,4 +23,4 @@ config OPTEE_INSECURE_LOAD_IMAGE https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… Additional documentation on kernel security risks are at - Documentation/staging/tee.rst. + Documentation/tee/op-tee.rst. -- 2.34.1

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