- OP-TEE - lists.trustedfirmware.org

Needing some help with OPTEE API and possible support

by Stroble, Matthew Scott

Hi OPTEE Developers, I am writing this email to you because we need some assistance with working with OPTEE OS in both QEMU v7 and a hardware implementation (rock pi 4b). We are currently able to get some aspects of our project working in the QEMU environment and need some assistance with OPTEE OS API documentation and possibly some help implementing a protocol we have developed to work with OPTEE OS. If possible we would like to schedule a Microsoft Teams meeting. Thank you for our time, Matthew

2 years, 7 months

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Re: optee xtest cannot run success stably

by 梅建强(禹夜)

Hi, Jens, We seem to have found the answer following the comment you gave in the issue: https://github.com/OP-TEE/optee_os/issues/5877 <https://github.com/OP-TEE/optee_os/issues/5877 > The reason seems to be that the system has more non-secure memory than what OP-TEE is aware of. When our system memory DRAM size is 32GB, optee has the following configuration for non-secure state memory: #define DRAM1_BASE 0x880000000UL #define DRAM1_SIZE 0x780000000UL On another device, our system memory DRAM size is 64G, optee uses the above configuration for non-secure memory. And xtest will not run stably. In addition, I would like to ask you a few questions in order to understand the problem better. 1. System has more non-secure memory than what OP-TEE is aware of, and optee will not run stably. Why? What is the root cause of TEEC_ERROR_OUT_OF_MEMORY on the issue? I'll do some research on it myself, meanwhile I hope you could give us some insights. 2. When I execute the following command, for i in {1.. 10}; do ./xtest&; done; xtest prints out of order, And the following error is reported: E/TC:032 002 mobj_ffa_get_by_cookie:356 possible spinlock deadlock reminder 1 E/TC:070 mobj_ffa_unregister_by_cookie:310 possible spinlock deadlock reminder 1 E/TC:004 003 mobj_ffa_get_by_cookie:356 possible spinlock deadlock reminder 1 E/TC:058 001 mobj_ffa_get_by_cookie:356 possible spinlock deadlock reminder 1 Then the system hangs and restarts automatically. Does optee currently support running multiple TAs in parallel? Is the maximum number of TAs running in parallel equal to the number of vcpus? 3. The values of MAX_XLAT_TABLES and CFG_CORE_HEAP_SIZE also seem to affect the stability of the system. What configurations, such as the number of cores, should I pay attention to if I want to configure appropriate values for these options? Thanks a lot. Regards, Yuye. ------------------------------------------------------------------ 发件人：Jens Wiklander <jens.wiklander(a)linaro.org> 发送时间：2023年3月20日(星期一) 15:05 收件人：梅建强(禹夜) <meijianqiang.mjq(a)alibaba-inc.com> 抄　送：Olivier Deprez <Olivier.Deprez(a)arm.com>; hafnium <hafnium(a)lists.trustedfirmware.org>; op-tee <op-tee(a)lists.trustedfirmware.org> 主　题：Re: optee xtest cannot run success stably Hi Yuye, Comment below. On Mon, Mar 20, 2023 at 4:43 AM 梅建强(禹夜) <meijianqiang.mjq(a)alibaba-inc.com> wrote: > Hi, experts > > Recently, we are testing the stability for running optee xtest with environment that hafnium runs as SPMC and optee runs on SPMC as SP. > When we reboot the system, xtest failed on some cases with TEEC_ERROR_OUT_OF_MEMORY. > It seems to be that there is an insufficient memory allocation somewhere in the chain. > We tried the following: > Using Single core startup, > Increased optee MAX_XLAT_TABLES size to 16, > Increased optee CFG_CORE_HEAP_SIZE to 0x2000000, > Increasing the size of optee CFG_TEE_RAM_VA_SIZE to 0x4000000, > Increasing the size of hafnium heap_pages to 8192, > But nothing seems to be working. > Can you offer any help or suggestions? It would help if you could pinpoint the source of the out-of-memory error. I guess it happens somewhere during mobj_ffa_get_by_cookie(), where especially thread_spmc_populate_mobj_from_rx() is interesting. It could also be worth setting CFG_CORE_DUMP_OOM=y, it's easy to enable but I'm afraid it's more of a long shot. Cheers, Jens > Some other configuration for optee is attached in the issue: > https://github.com/OP-TEE/optee_os/issues/5893 <https://github.com/OP-TEE/optee_os/issues/5893 > > > Regards, > Yuye. >

2 years, 7 months

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optee xtest cannot run success stably

by 梅建强(禹夜)

Hi, experts Recently, we are testing the stability for running optee xtest with environment that hafnium runs as SPMC and optee runs on SPMC as SP. When we reboot the system, xtest failed on some cases with TEEC_ERROR_OUT_OF_MEMORY. It seems to be that there is an insufficient memory allocation somewhere in the chain. We tried the following: Using Single core startup, Increased optee MAX_XLAT_TABLES size to 16, Increased optee CFG_CORE_HEAP_SIZE to 0x2000000, Increasing the size of optee CFG_TEE_RAM_VA_SIZE to 0x4000000, Increasing the size of hafnium heap_pages to 8192, But nothing seems to be working. Can you offer any help or suggestions? Some other configuration for optee is attached in the issue: https://github.com/OP-TEE/optee_os/issues/5893 <https://github.com/OP-TEE/optee_os/issues/5893 > Regards, Yuye.

2 years, 7 months

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[PATCH v10] tee: optee: Add SMC for loading OP-TEE image

by Jeffrey Kardatzke

Adds an SMC call that will pass an OP-TEE binary image to EL3 and instruct it to load it as the BL32 payload. This works in conjunction with a feature added to Trusted Firmware for ARMv8 and above architectures that supports this. The main purpose of this change is to facilitate updating the OP-TEE component on devices via a rootfs change rather than having to do a firmware update. Further details are linked to in the Kconfig file. Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)chromium.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v10: - Fixed tee.rst documentation formatting Changes in v9: - Add CPU hotplug callback to init on all cores at startup Changes in v8: - Renamed params and fixed alignment issue Changes in v7: - Added documentation to Documentation/staging/tee.rst Changes in v6: - Expanded Kconfig documentation Changes in v5: - Renamed config option - Added runtime warning when config is used Changes in v4: - Update commit message - Added more documentation - Renamed config option, added ARM64 dependency Changes in v3: - Removed state tracking for driver reload - Check UID of service to verify it needs image load Changes in v2: - Fixed compile issue when feature is disabled - Addressed minor comments - Added state tracking for driver reload Documentation/staging/tee.rst | 41 +++++++++++ drivers/tee/optee/Kconfig | 17 +++++ drivers/tee/optee/optee_msg.h | 12 +++ drivers/tee/optee/optee_smc.h | 24 ++++++ drivers/tee/optee/smc_abi.c | 134 ++++++++++++++++++++++++++++++++++ 5 files changed, 228 insertions(+) diff --git a/Documentation/staging/tee.rst b/Documentation/staging/tee.rst index 498343c7ab08..6e90ee726880 100644 --- a/Documentation/staging/tee.rst +++ b/Documentation/staging/tee.rst @@ -214,6 +214,47 @@ 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 documentation there +explains the security threat associated with enabling this as well as +mitigations at the firmware and platform level. +https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_model.html + +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. + Migitation: 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 an included + driver rather than a module to prevent exploits that may cause the module to + not be loaded. + AMD-TEE driver ============== diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig index f121c224e682..70898bbd5809 100644 --- a/drivers/tee/optee/Kconfig +++ b/drivers/tee/optee/Kconfig @@ -7,3 +7,20 @@ config OPTEE help This implements the OP-TEE Trusted Execution Environment (TEE) driver. + +config OPTEE_INSECURE_LOAD_IMAGE + bool "Load OP-TEE image as firmware" + default n + depends on OPTEE && ARM64 + help + This loads the BL32 image for OP-TEE as firmware when the driver is + probed. This returns -EPROBE_DEFER until the firmware is loadable from + the filesystem which is determined by checking the system_state until + it is in SYSTEM_RUNNING. This also requires enabling the corresponding + option in Trusted Firmware for Arm. The documentation there explains + the security threat associated with enabling this as well as + mitigations at the firmware and platform level. + https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… + + Additional documentation on kernel security risks are at + Documentation/staging/tee.rst. diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 70e9cc2ee96b..e8840a82b983 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -241,11 +241,23 @@ struct optee_msg_arg { * 384fb3e0-e7f8-11e3-af63-0002a5d5c51b. * Represented in 4 32-bit words in OPTEE_MSG_UID_0, OPTEE_MSG_UID_1, * OPTEE_MSG_UID_2, OPTEE_MSG_UID_3. + * + * In the case where the OP-TEE image is loaded by the kernel, this will + * initially return an alternate UID to reflect that we are communicating with + * the TF-A image loading service at that time instead of OP-TEE. That UID is: + * a3fbeab1-1246-315d-c7c4-06b9c03cbea4. + * Represented in 4 32-bit words in OPTEE_MSG_IMAGE_LOAD_UID_0, + * OPTEE_MSG_IMAGE_LOAD_UID_1, OPTEE_MSG_IMAGE_LOAD_UID_2, + * OPTEE_MSG_IMAGE_LOAD_UID_3. */ #define OPTEE_MSG_UID_0 0x384fb3e0 #define OPTEE_MSG_UID_1 0xe7f811e3 #define OPTEE_MSG_UID_2 0xaf630002 #define OPTEE_MSG_UID_3 0xa5d5c51b +#define OPTEE_MSG_IMAGE_LOAD_UID_0 0xa3fbeab1 +#define OPTEE_MSG_IMAGE_LOAD_UID_1 0x1246315d +#define OPTEE_MSG_IMAGE_LOAD_UID_2 0xc7c406b9 +#define OPTEE_MSG_IMAGE_LOAD_UID_3 0xc03cbea4 #define OPTEE_MSG_FUNCID_CALLS_UID 0xFF01 /* diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h index 73b5e7760d10..7d9fa426505b 100644 --- a/drivers/tee/optee/optee_smc.h +++ b/drivers/tee/optee/optee_smc.h @@ -104,6 +104,30 @@ struct optee_smc_call_get_os_revision_result { unsigned long reserved1; }; +/* + * Load Trusted OS from optee/tee.bin in the Linux firmware. + * + * WARNING: Use this cautiously as it could lead to insecure loading of the + * Trusted OS. + * This SMC instructs EL3 to load a binary and execute it as the Trusted OS. + * + * Call register usage: + * a0 SMC Function ID, OPTEE_SMC_CALL_LOAD_IMAGE + * a1 Upper 32bit of a 64bit size for the payload + * a2 Lower 32bit of a 64bit size for the payload + * a3 Upper 32bit of the physical address for the payload + * a4 Lower 32bit of the physical address for the payload + * + * The payload is in the OP-TEE image format. + * + * Returns result in a0, 0 on success and an error code otherwise. + */ +#define OPTEE_SMC_FUNCID_LOAD_IMAGE 2 +#define OPTEE_SMC_CALL_LOAD_IMAGE \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_TRUSTED_OS_END, \ + OPTEE_SMC_FUNCID_LOAD_IMAGE) + /* * Call with struct optee_msg_arg as argument * diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c index a1c1fa1a9c28..fcbcd0c0c3aa 100644 --- a/drivers/tee/optee/smc_abi.c +++ b/drivers/tee/optee/smc_abi.c @@ -7,10 +7,13 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/arm-smccc.h> +#include <linux/cpuhotplug.h> #include <linux/errno.h> +#include <linux/firmware.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/irqdomain.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/of.h> @@ -1149,6 +1152,22 @@ static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn) return false; } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE +static bool optee_msg_api_uid_is_optee_image_load(optee_invoke_fn *invoke_fn) +{ + struct arm_smccc_res res; + + invoke_fn(OPTEE_SMC_CALLS_UID, 0, 0, 0, 0, 0, 0, 0, &res); + + if (res.a0 == OPTEE_MSG_IMAGE_LOAD_UID_0 && + res.a1 == OPTEE_MSG_IMAGE_LOAD_UID_1 && + res.a2 == OPTEE_MSG_IMAGE_LOAD_UID_2 && + res.a3 == OPTEE_MSG_IMAGE_LOAD_UID_3) + return true; + return false; +} +#endif + static void optee_msg_get_os_revision(optee_invoke_fn *invoke_fn) { union { @@ -1354,6 +1373,117 @@ static void optee_shutdown(struct platform_device *pdev) optee_disable_shm_cache(optee); } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE + +#define OPTEE_FW_IMAGE "optee/tee.bin" + +static optee_invoke_fn *cpuhp_invoke_fn; + +static int optee_cpuhp_probe(unsigned int cpu) +{ + /* + * Invoking a call on a CPU will cause OP-TEE to perform the required + * setup for that CPU. Just invoke the call to get the UID since that + * has no side effects. + */ + if (optee_msg_api_uid_is_optee_api(cpuhp_invoke_fn)) + return 0; + else + return -EINVAL; +} + +static int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + const struct firmware *fw = NULL; + struct arm_smccc_res res; + phys_addr_t data_pa; + u8 *data_buf = NULL; + u64 data_size; + u32 data_pa_high, data_pa_low; + u32 data_size_high, data_size_low; + int rc; + int hp_state; + + if (!optee_msg_api_uid_is_optee_image_load(invoke_fn)) + return 0; + + rc = request_firmware(&fw, OPTEE_FW_IMAGE, &pdev->dev); + if (rc) { + /* + * The firmware in the rootfs will not be accessible until we + * are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until + * that point. + */ + if (system_state < SYSTEM_RUNNING) + return -EPROBE_DEFER; + goto fw_err; + } + + data_size = fw->size; + /* + * This uses the GFP_DMA flag to ensure we are allocated memory in the + * 32-bit space since TF-A cannot map memory beyond the 32-bit boundary. + */ + data_buf = kmalloc(fw->size, GFP_KERNEL | GFP_DMA); + if (!data_buf) { + rc = -ENOMEM; + goto fw_err; + } + memcpy(data_buf, fw->data, fw->size); + data_pa = virt_to_phys(data_buf); + reg_pair_from_64(&data_pa_high, &data_pa_low, data_pa); + reg_pair_from_64(&data_size_high, &data_size_low, data_size); + goto fw_load; + +fw_err: + pr_warn("image loading failed\n"); + data_pa_high = data_pa_low = data_size_high = data_size_low = 0; + +fw_load: + /* + * Always invoke the SMC, even if loading the image fails, to indicate + * to EL3 that we have passed the point where it should allow invoking + * this SMC. + */ + pr_warn("OP-TEE image loaded from kernel, this can be insecure"); + invoke_fn(OPTEE_SMC_CALL_LOAD_IMAGE, data_size_high, data_size_low, + data_pa_high, data_pa_low, 0, 0, 0, &res); + if (!rc) + rc = res.a0; + if (fw) + release_firmware(fw); + kfree(data_buf); + + if (!rc) { + /* + * We need to initialize OP-TEE on all other running cores as + * well. Any cores that aren't running yet will get initialized + * when they are brought up by the power management functions in + * TF-A which are registered by the OP-TEE SPD. Due to that we + * can un-register the callback right after registering it. + */ + cpuhp_invoke_fn = invoke_fn; + hp_state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "optee:probe", + optee_cpuhp_probe, NULL); + if (hp_state < 0) { + pr_warn("Failed with CPU hotplug setup for OP-TEE"); + return -EINVAL; + } + cpuhp_remove_state(hp_state); + cpuhp_invoke_fn = NULL; + } + + return rc; +} +#else +static inline int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + return 0; +} +#endif + static int optee_probe(struct platform_device *pdev) { optee_invoke_fn *invoke_fn; @@ -1372,6 +1502,10 @@ static int optee_probe(struct platform_device *pdev) if (IS_ERR(invoke_fn)) return PTR_ERR(invoke_fn); + rc = optee_load_fw(pdev, invoke_fn); + if (rc) + return rc; + if (!optee_msg_api_uid_is_optee_api(invoke_fn)) { pr_warn("api uid mismatch\n"); return -EINVAL; -- 2.40.0.rc1.284.g88254d51c5-goog

2 years, 7 months

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[PATCH v4 0/8] Export platform features from ccp driver

by Mario Limonciello

The i2c-designware-amdpsp driver communicates with a platform features mailbox provided by the PSP. The address used for communication is discovered via a non-architecturally guaranteed mechanism. To better scale, export a feature for communication with platform features directly from the ccp driver. v3->v4 Drop the ACPI ID as result of confirmation with internal team. Future platforms should use doorbell, so will treat Cezanne as quirk and assume doorbell going forward. Mario Limonciello (8): crypto: ccp: Drop TEE support for IRQ handler crypto: ccp: Add a header for multiple drivers to use `__psp_pa` crypto: ccp: Move some PSP mailbox bit definitions into common header crypto: ccp: Add support for an interface for platform features crypto: ccp: Enable platform access interface on client PSP parts i2c: designware: Use PCI PSP driver for communication crypto: ccp: Add support for ringing a platform doorbell i2c: designware: Add doorbell support for Skyrim arch/x86/kvm/svm/sev.c | 1 + drivers/crypto/ccp/Makefile | 3 +- drivers/crypto/ccp/platform-access.c | 232 ++++++++++++++++++++ drivers/crypto/ccp/platform-access.h | 35 +++ drivers/crypto/ccp/psp-dev.c | 32 +-- drivers/crypto/ccp/psp-dev.h | 11 +- drivers/crypto/ccp/sev-dev.c | 16 +- drivers/crypto/ccp/sev-dev.h | 2 +- drivers/crypto/ccp/sp-dev.h | 10 + drivers/crypto/ccp/sp-pci.c | 9 + drivers/crypto/ccp/tee-dev.c | 17 +- drivers/i2c/busses/Kconfig | 2 +- drivers/i2c/busses/i2c-designware-amdpsp.c | 188 ++++------------ drivers/i2c/busses/i2c-designware-core.h | 1 - drivers/i2c/busses/i2c-designware-platdrv.c | 1 - drivers/tee/amdtee/call.c | 2 +- drivers/tee/amdtee/shm_pool.c | 2 +- include/linux/psp-platform-access.h | 65 ++++++ include/linux/psp-sev.h | 8 - include/linux/psp.h | 29 +++ 20 files changed, 461 insertions(+), 205 deletions(-) create mode 100644 drivers/crypto/ccp/platform-access.c create mode 100644 drivers/crypto/ccp/platform-access.h create mode 100644 include/linux/psp-platform-access.h create mode 100644 include/linux/psp.h -- 2.34.1

2 years, 7 months

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[PATCH v9] tee: optee: Add SMC for loading OP-TEE image

by Jeffrey Kardatzke

Adds an SMC call that will pass an OP-TEE binary image to EL3 and instruct it to load it as the BL32 payload. This works in conjunction with a feature added to Trusted Firmware for ARMv8 and above architectures that supports this. The main purpose of this change is to facilitate updating the OP-TEE component on devices via a rootfs change rather than having to do a firmware update. Further details are linked to in the Kconfig file. Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)chromium.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v9: - Add CPU hotplug callback to init on all cores at startup Changes in v8: - Renamed params and fixed alignment issue Changes in v7: - Added documentation to Documentation/staging/tee.rst Changes in v6: - Expanded Kconfig documentation Changes in v5: - Renamed config option - Added runtime warning when config is used Changes in v4: - Update commit message - Added more documentation - Renamed config option, added ARM64 dependency Changes in v3: - Removed state tracking for driver reload - Check UID of service to verify it needs image load Changes in v2: - Fixed compile issue when feature is disabled - Addressed minor comments - Added state tracking for driver reload Documentation/staging/tee.rst | 41 +++++++++++ drivers/tee/optee/Kconfig | 17 +++++ drivers/tee/optee/optee_msg.h | 12 +++ drivers/tee/optee/optee_smc.h | 24 ++++++ drivers/tee/optee/smc_abi.c | 134 ++++++++++++++++++++++++++++++++++ 5 files changed, 228 insertions(+) diff --git a/Documentation/staging/tee.rst b/Documentation/staging/tee.rst index 498343c7ab08..315aa8e35e6b 100644 --- a/Documentation/staging/tee.rst +++ b/Documentation/staging/tee.rst @@ -214,6 +214,47 @@ 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 documentation there +explains the security threat associated with enabling this as well as +mitigations at the firmware and platform level. +https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_model.html + +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. + Migitation: 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. +3. 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 an included + driver rather than a module to prevent exploits that may cause + the module to not be loaded. + AMD-TEE driver ============== diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig index f121c224e682..70898bbd5809 100644 --- a/drivers/tee/optee/Kconfig +++ b/drivers/tee/optee/Kconfig @@ -7,3 +7,20 @@ config OPTEE help This implements the OP-TEE Trusted Execution Environment (TEE) driver. + +config OPTEE_INSECURE_LOAD_IMAGE + bool "Load OP-TEE image as firmware" + default n + depends on OPTEE && ARM64 + help + This loads the BL32 image for OP-TEE as firmware when the driver is + probed. This returns -EPROBE_DEFER until the firmware is loadable from + the filesystem which is determined by checking the system_state until + it is in SYSTEM_RUNNING. This also requires enabling the corresponding + option in Trusted Firmware for Arm. The documentation there explains + the security threat associated with enabling this as well as + mitigations at the firmware and platform level. + https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… + + Additional documentation on kernel security risks are at + Documentation/staging/tee.rst. diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 70e9cc2ee96b..e8840a82b983 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -241,11 +241,23 @@ struct optee_msg_arg { * 384fb3e0-e7f8-11e3-af63-0002a5d5c51b. * Represented in 4 32-bit words in OPTEE_MSG_UID_0, OPTEE_MSG_UID_1, * OPTEE_MSG_UID_2, OPTEE_MSG_UID_3. + * + * In the case where the OP-TEE image is loaded by the kernel, this will + * initially return an alternate UID to reflect that we are communicating with + * the TF-A image loading service at that time instead of OP-TEE. That UID is: + * a3fbeab1-1246-315d-c7c4-06b9c03cbea4. + * Represented in 4 32-bit words in OPTEE_MSG_IMAGE_LOAD_UID_0, + * OPTEE_MSG_IMAGE_LOAD_UID_1, OPTEE_MSG_IMAGE_LOAD_UID_2, + * OPTEE_MSG_IMAGE_LOAD_UID_3. */ #define OPTEE_MSG_UID_0 0x384fb3e0 #define OPTEE_MSG_UID_1 0xe7f811e3 #define OPTEE_MSG_UID_2 0xaf630002 #define OPTEE_MSG_UID_3 0xa5d5c51b +#define OPTEE_MSG_IMAGE_LOAD_UID_0 0xa3fbeab1 +#define OPTEE_MSG_IMAGE_LOAD_UID_1 0x1246315d +#define OPTEE_MSG_IMAGE_LOAD_UID_2 0xc7c406b9 +#define OPTEE_MSG_IMAGE_LOAD_UID_3 0xc03cbea4 #define OPTEE_MSG_FUNCID_CALLS_UID 0xFF01 /* diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h index 73b5e7760d10..7d9fa426505b 100644 --- a/drivers/tee/optee/optee_smc.h +++ b/drivers/tee/optee/optee_smc.h @@ -104,6 +104,30 @@ struct optee_smc_call_get_os_revision_result { unsigned long reserved1; }; +/* + * Load Trusted OS from optee/tee.bin in the Linux firmware. + * + * WARNING: Use this cautiously as it could lead to insecure loading of the + * Trusted OS. + * This SMC instructs EL3 to load a binary and execute it as the Trusted OS. + * + * Call register usage: + * a0 SMC Function ID, OPTEE_SMC_CALL_LOAD_IMAGE + * a1 Upper 32bit of a 64bit size for the payload + * a2 Lower 32bit of a 64bit size for the payload + * a3 Upper 32bit of the physical address for the payload + * a4 Lower 32bit of the physical address for the payload + * + * The payload is in the OP-TEE image format. + * + * Returns result in a0, 0 on success and an error code otherwise. + */ +#define OPTEE_SMC_FUNCID_LOAD_IMAGE 2 +#define OPTEE_SMC_CALL_LOAD_IMAGE \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_TRUSTED_OS_END, \ + OPTEE_SMC_FUNCID_LOAD_IMAGE) + /* * Call with struct optee_msg_arg as argument * diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c index a1c1fa1a9c28..fcbcd0c0c3aa 100644 --- a/drivers/tee/optee/smc_abi.c +++ b/drivers/tee/optee/smc_abi.c @@ -7,10 +7,13 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/arm-smccc.h> +#include <linux/cpuhotplug.h> #include <linux/errno.h> +#include <linux/firmware.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/irqdomain.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/of.h> @@ -1149,6 +1152,22 @@ static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn) return false; } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE +static bool optee_msg_api_uid_is_optee_image_load(optee_invoke_fn *invoke_fn) +{ + struct arm_smccc_res res; + + invoke_fn(OPTEE_SMC_CALLS_UID, 0, 0, 0, 0, 0, 0, 0, &res); + + if (res.a0 == OPTEE_MSG_IMAGE_LOAD_UID_0 && + res.a1 == OPTEE_MSG_IMAGE_LOAD_UID_1 && + res.a2 == OPTEE_MSG_IMAGE_LOAD_UID_2 && + res.a3 == OPTEE_MSG_IMAGE_LOAD_UID_3) + return true; + return false; +} +#endif + static void optee_msg_get_os_revision(optee_invoke_fn *invoke_fn) { union { @@ -1354,6 +1373,117 @@ static void optee_shutdown(struct platform_device *pdev) optee_disable_shm_cache(optee); } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE + +#define OPTEE_FW_IMAGE "optee/tee.bin" + +static optee_invoke_fn *cpuhp_invoke_fn; + +static int optee_cpuhp_probe(unsigned int cpu) +{ + /* + * Invoking a call on a CPU will cause OP-TEE to perform the required + * setup for that CPU. Just invoke the call to get the UID since that + * has no side effects. + */ + if (optee_msg_api_uid_is_optee_api(cpuhp_invoke_fn)) + return 0; + else + return -EINVAL; +} + +static int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + const struct firmware *fw = NULL; + struct arm_smccc_res res; + phys_addr_t data_pa; + u8 *data_buf = NULL; + u64 data_size; + u32 data_pa_high, data_pa_low; + u32 data_size_high, data_size_low; + int rc; + int hp_state; + + if (!optee_msg_api_uid_is_optee_image_load(invoke_fn)) + return 0; + + rc = request_firmware(&fw, OPTEE_FW_IMAGE, &pdev->dev); + if (rc) { + /* + * The firmware in the rootfs will not be accessible until we + * are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until + * that point. + */ + if (system_state < SYSTEM_RUNNING) + return -EPROBE_DEFER; + goto fw_err; + } + + data_size = fw->size; + /* + * This uses the GFP_DMA flag to ensure we are allocated memory in the + * 32-bit space since TF-A cannot map memory beyond the 32-bit boundary. + */ + data_buf = kmalloc(fw->size, GFP_KERNEL | GFP_DMA); + if (!data_buf) { + rc = -ENOMEM; + goto fw_err; + } + memcpy(data_buf, fw->data, fw->size); + data_pa = virt_to_phys(data_buf); + reg_pair_from_64(&data_pa_high, &data_pa_low, data_pa); + reg_pair_from_64(&data_size_high, &data_size_low, data_size); + goto fw_load; + +fw_err: + pr_warn("image loading failed\n"); + data_pa_high = data_pa_low = data_size_high = data_size_low = 0; + +fw_load: + /* + * Always invoke the SMC, even if loading the image fails, to indicate + * to EL3 that we have passed the point where it should allow invoking + * this SMC. + */ + pr_warn("OP-TEE image loaded from kernel, this can be insecure"); + invoke_fn(OPTEE_SMC_CALL_LOAD_IMAGE, data_size_high, data_size_low, + data_pa_high, data_pa_low, 0, 0, 0, &res); + if (!rc) + rc = res.a0; + if (fw) + release_firmware(fw); + kfree(data_buf); + + if (!rc) { + /* + * We need to initialize OP-TEE on all other running cores as + * well. Any cores that aren't running yet will get initialized + * when they are brought up by the power management functions in + * TF-A which are registered by the OP-TEE SPD. Due to that we + * can un-register the callback right after registering it. + */ + cpuhp_invoke_fn = invoke_fn; + hp_state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "optee:probe", + optee_cpuhp_probe, NULL); + if (hp_state < 0) { + pr_warn("Failed with CPU hotplug setup for OP-TEE"); + return -EINVAL; + } + cpuhp_remove_state(hp_state); + cpuhp_invoke_fn = NULL; + } + + return rc; +} +#else +static inline int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + return 0; +} +#endif + static int optee_probe(struct platform_device *pdev) { optee_invoke_fn *invoke_fn; @@ -1372,6 +1502,10 @@ static int optee_probe(struct platform_device *pdev) if (IS_ERR(invoke_fn)) return PTR_ERR(invoke_fn); + rc = optee_load_fw(pdev, invoke_fn); + if (rc) + return rc; + if (!optee_msg_api_uid_is_optee_api(invoke_fn)) { pr_warn("api uid mismatch\n"); return -EINVAL; -- 2.40.0.rc1.284.g88254d51c5-goog

2 years, 7 months

2
1
0 0

[PATCH v6] tee: optee: Add SMC for loading OP-TEE image

by Jeffrey Kardatzke

Adds an SMC call that will pass an OP-TEE binary image to EL3 and instruct it to load it as the BL32 payload. This works in conjunction with a feature added to Trusted Firmware for ARMv8 and above architectures that supports this. The main purpose of this change is to facilitate updating the OP-TEE component on devices via a rootfs change rather than having to do a firmware update. Further details are linked to in the Kconfig file. Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)chromium.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v6: - Expanded Kconfig documentation Changes in v5: - Renamed config option - Added runtime warning when config is used Changes in v4: - Update commit message - Added more documentation - Renamed config option, added ARM64 dependency Changes in v3: - Removed state tracking for driver reload - Check UID of service to verify it needs image load Changes in v2: - Fixed compile issue when feature is disabled - Addressed minor comments - Added state tracking for driver reload drivers/tee/optee/Kconfig | 29 +++++++++++ drivers/tee/optee/optee_msg.h | 12 +++++ drivers/tee/optee/optee_smc.h | 24 +++++++++ drivers/tee/optee/smc_abi.c | 97 +++++++++++++++++++++++++++++++++++ 4 files changed, 162 insertions(+) diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig index f121c224e682..8d4836c58486 100644 --- a/drivers/tee/optee/Kconfig +++ b/drivers/tee/optee/Kconfig @@ -7,3 +7,32 @@ config OPTEE help This implements the OP-TEE Trusted Execution Environment (TEE) driver. + +config OPTEE_INSECURE_LOAD_IMAGE + bool "Load OP-TEE image as firmware" + default n + depends on OPTEE && ARM64 + help + This loads the BL32 image for OP-TEE as firmware when the driver is + probed. This returns -EPROBE_DEFER until the firmware is loadable from + the filesystem which is determined by checking the system_state until + it is in SYSTEM_RUNNING. This also requires enabling the corresponding + option in Trusted Firmware for Arm. The documentation there explains + the security threat associated with enabling this as well as + mitigations at the firmware and platform level. + https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… + + When utilizing this option, the following mitigations should be + implemented to prevent attacks at the kernel level. + 1. There must be boot chain security that verifies the kernel and + rootfs, otherwise an attacker can modify the loaded OP-TEE binary. + 2. It is recommended to build it as an included driver rather than + a module to prevent exploits that may cause the module to not be + loaded. + 3. 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. + 4. 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 (such a USB). diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 70e9cc2ee96b..e8840a82b983 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -241,11 +241,23 @@ struct optee_msg_arg { * 384fb3e0-e7f8-11e3-af63-0002a5d5c51b. * Represented in 4 32-bit words in OPTEE_MSG_UID_0, OPTEE_MSG_UID_1, * OPTEE_MSG_UID_2, OPTEE_MSG_UID_3. + * + * In the case where the OP-TEE image is loaded by the kernel, this will + * initially return an alternate UID to reflect that we are communicating with + * the TF-A image loading service at that time instead of OP-TEE. That UID is: + * a3fbeab1-1246-315d-c7c4-06b9c03cbea4. + * Represented in 4 32-bit words in OPTEE_MSG_IMAGE_LOAD_UID_0, + * OPTEE_MSG_IMAGE_LOAD_UID_1, OPTEE_MSG_IMAGE_LOAD_UID_2, + * OPTEE_MSG_IMAGE_LOAD_UID_3. */ #define OPTEE_MSG_UID_0 0x384fb3e0 #define OPTEE_MSG_UID_1 0xe7f811e3 #define OPTEE_MSG_UID_2 0xaf630002 #define OPTEE_MSG_UID_3 0xa5d5c51b +#define OPTEE_MSG_IMAGE_LOAD_UID_0 0xa3fbeab1 +#define OPTEE_MSG_IMAGE_LOAD_UID_1 0x1246315d +#define OPTEE_MSG_IMAGE_LOAD_UID_2 0xc7c406b9 +#define OPTEE_MSG_IMAGE_LOAD_UID_3 0xc03cbea4 #define OPTEE_MSG_FUNCID_CALLS_UID 0xFF01 /* diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h index 73b5e7760d10..7d9fa426505b 100644 --- a/drivers/tee/optee/optee_smc.h +++ b/drivers/tee/optee/optee_smc.h @@ -104,6 +104,30 @@ struct optee_smc_call_get_os_revision_result { unsigned long reserved1; }; +/* + * Load Trusted OS from optee/tee.bin in the Linux firmware. + * + * WARNING: Use this cautiously as it could lead to insecure loading of the + * Trusted OS. + * This SMC instructs EL3 to load a binary and execute it as the Trusted OS. + * + * Call register usage: + * a0 SMC Function ID, OPTEE_SMC_CALL_LOAD_IMAGE + * a1 Upper 32bit of a 64bit size for the payload + * a2 Lower 32bit of a 64bit size for the payload + * a3 Upper 32bit of the physical address for the payload + * a4 Lower 32bit of the physical address for the payload + * + * The payload is in the OP-TEE image format. + * + * Returns result in a0, 0 on success and an error code otherwise. + */ +#define OPTEE_SMC_FUNCID_LOAD_IMAGE 2 +#define OPTEE_SMC_CALL_LOAD_IMAGE \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_TRUSTED_OS_END, \ + OPTEE_SMC_FUNCID_LOAD_IMAGE) + /* * Call with struct optee_msg_arg as argument * diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c index a1c1fa1a9c28..00b6b69b6f79 100644 --- a/drivers/tee/optee/smc_abi.c +++ b/drivers/tee/optee/smc_abi.c @@ -8,9 +8,11 @@ #include <linux/arm-smccc.h> #include <linux/errno.h> +#include <linux/firmware.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/irqdomain.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/of.h> @@ -1149,6 +1151,22 @@ static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn) return false; } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE +static bool optee_msg_api_uid_is_optee_image_load(optee_invoke_fn *invoke_fn) +{ + struct arm_smccc_res res; + + invoke_fn(OPTEE_SMC_CALLS_UID, 0, 0, 0, 0, 0, 0, 0, &res); + + if (res.a0 == OPTEE_MSG_IMAGE_LOAD_UID_0 && + res.a1 == OPTEE_MSG_IMAGE_LOAD_UID_1 && + res.a2 == OPTEE_MSG_IMAGE_LOAD_UID_2 && + res.a3 == OPTEE_MSG_IMAGE_LOAD_UID_3) + return true; + return false; +} +#endif + static void optee_msg_get_os_revision(optee_invoke_fn *invoke_fn) { union { @@ -1354,6 +1372,81 @@ static void optee_shutdown(struct platform_device *pdev) optee_disable_shm_cache(optee); } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE + +#define OPTEE_FW_IMAGE "optee/tee.bin" + +static int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + const struct firmware *fw = NULL; + struct arm_smccc_res res; + phys_addr_t data_pa; + u8 *data_buf = NULL; + u64 data_size; + u32 data_pa_high, data_pa_low; + u32 data_size_high, data_size_low; + int rc; + + if (!optee_msg_api_uid_is_optee_image_load(invoke_fn)) + return 0; + + rc = request_firmware(&fw, OPTEE_FW_IMAGE, &pdev->dev); + if (rc) { + /* + * The firmware in the rootfs will not be accessible until we + * are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until + * that point. + */ + if (system_state < SYSTEM_RUNNING) + return -EPROBE_DEFER; + goto fw_err; + } + + data_size = fw->size; + /* + * This uses the GFP_DMA flag to ensure we are allocated memory in the + * 32-bit space since TF-A cannot map memory beyond the 32-bit boundary. + */ + data_buf = kmalloc(fw->size, GFP_KERNEL | GFP_DMA); + if (!data_buf) { + rc = -ENOMEM; + goto fw_err; + } + memcpy(data_buf, fw->data, fw->size); + data_pa = virt_to_phys(data_buf); + reg_pair_from_64(&data_pa_high, &data_pa_low, data_pa); + reg_pair_from_64(&data_size_high, &data_size_low, data_size); + goto fw_load; + +fw_err: + pr_warn("image loading failed\n"); + data_pa_high = data_pa_low = data_size_high = data_size_low = 0; + +fw_load: + /* + * Always invoke the SMC, even if loading the image fails, to indicate + * to EL3 that we have passed the point where it should allow invoking + * this SMC. + */ + pr_warn("OP-TEE image loaded from kernel, this can be insecure"); + invoke_fn(OPTEE_SMC_CALL_LOAD_IMAGE, data_size_high, data_size_low, + data_pa_high, data_pa_low, 0, 0, 0, &res); + if (!rc) + rc = res.a0; + if (fw) + release_firmware(fw); + kfree(data_buf); + + return rc; +} +#else +static inline int optee_load_fw(struct platform_device *__unused1, + optee_invoke_fn *__unused2) { + return 0; +} +#endif + static int optee_probe(struct platform_device *pdev) { optee_invoke_fn *invoke_fn; @@ -1372,6 +1465,10 @@ static int optee_probe(struct platform_device *pdev) if (IS_ERR(invoke_fn)) return PTR_ERR(invoke_fn); + rc = optee_load_fw(pdev, invoke_fn); + if (rc) + return rc; + if (!optee_msg_api_uid_is_optee_api(invoke_fn)) { pr_warn("api uid mismatch\n"); return -EINVAL; -- 2.40.0.rc1.284.g88254d51c5-goog

2 years, 7 months

2
5
0 0

[PATCH] tee: optee: Fix typo Unuspported -> Unsupported

by Jules Maselbas

Fix typo Unuspported -> Unsupported Signed-off-by: Jules Maselbas <jmaselbas(a)kalray.eu> --- drivers/tee/optee/call.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c index 290b1bb0e9cd..df5fb5410b72 100644 --- a/drivers/tee/optee/call.c +++ b/drivers/tee/optee/call.c @@ -488,7 +488,7 @@ static bool is_normal_memory(pgprot_t p) #elif defined(CONFIG_ARM64) return (pgprot_val(p) & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL); #else -#error "Unuspported architecture" +#error "Unsupported architecture" #endif } -- 2.17.1

2 years, 7 months

3
2
0 0

[GIT PULL] Fix spell error in OP-TEE driver for v6.3

by Jens Wiklander

Hello arm-soc maintainers, Please pull this small patch fixing a spell error in an error message in the OP-TEE driver. Thanks, Jens The following changes since commit eeac8ede17557680855031c6f305ece2378af326: Linux 6.3-rc2 (2023-03-12 16:36:44 -0700) are available in the Git repository at: https://git.linaro.org/people/jens.wiklander/linux-tee.git/ tags/optee-fix-for-v6.3 for you to fetch changes up to 172fa6366c0c84eda31f1bc34e6c3e4698786215: tee: optee: Fix typo Unuspported -> Unsupported (2023-03-14 11:57:03 +0100) ---------------------------------------------------------------- Fixes a spell error in an error message in the OP-TEE driver ---------------------------------------------------------------- Jules Maselbas (1): tee: optee: Fix typo Unuspported -> Unsupported drivers/tee/optee/call.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

2 years, 7 months

1
0
0 0

[PATCH v7] tee: optee: Add SMC for loading OP-TEE image

by Jeffrey Kardatzke

Adds an SMC call that will pass an OP-TEE binary image to EL3 and instruct it to load it as the BL32 payload. This works in conjunction with a feature added to Trusted Firmware for ARMv8 and above architectures that supports this. The main purpose of this change is to facilitate updating the OP-TEE component on devices via a rootfs change rather than having to do a firmware update. Further details are linked to in the Kconfig file. Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)chromium.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v7: - Added documentation to Documentation/staging/tee.rst Changes in v6: - Expanded Kconfig documentation Changes in v5: - Renamed config option - Added runtime warning when config is used Changes in v4: - Update commit message - Added more documentation - Renamed config option, added ARM64 dependency Changes in v3: - Removed state tracking for driver reload - Check UID of service to verify it needs image load Changes in v2: - Fixed compile issue when feature is disabled - Addressed minor comments - Added state tracking for driver reload Documentation/staging/tee.rst | 41 +++++++++++++++ drivers/tee/optee/Kconfig | 17 ++++++ drivers/tee/optee/optee_msg.h | 12 +++++ drivers/tee/optee/optee_smc.h | 24 +++++++++ drivers/tee/optee/smc_abi.c | 97 +++++++++++++++++++++++++++++++++++ 5 files changed, 191 insertions(+) diff --git a/Documentation/staging/tee.rst b/Documentation/staging/tee.rst index 498343c7ab08..315aa8e35e6b 100644 --- a/Documentation/staging/tee.rst +++ b/Documentation/staging/tee.rst @@ -214,6 +214,47 @@ 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 documentation there +explains the security threat associated with enabling this as well as +mitigations at the firmware and platform level. +https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_model.html + +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. + Migitation: 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. +3. 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 an included + driver rather than a module to prevent exploits that may cause + the module to not be loaded. + AMD-TEE driver ============== diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig index f121c224e682..70898bbd5809 100644 --- a/drivers/tee/optee/Kconfig +++ b/drivers/tee/optee/Kconfig @@ -7,3 +7,20 @@ config OPTEE help This implements the OP-TEE Trusted Execution Environment (TEE) driver. + +config OPTEE_INSECURE_LOAD_IMAGE + bool "Load OP-TEE image as firmware" + default n + depends on OPTEE && ARM64 + help + This loads the BL32 image for OP-TEE as firmware when the driver is + probed. This returns -EPROBE_DEFER until the firmware is loadable from + the filesystem which is determined by checking the system_state until + it is in SYSTEM_RUNNING. This also requires enabling the corresponding + option in Trusted Firmware for Arm. The documentation there explains + the security threat associated with enabling this as well as + mitigations at the firmware and platform level. + https://trustedfirmware-a.readthedocs.io/en/latest/threat_model/threat_mode… + + Additional documentation on kernel security risks are at + Documentation/staging/tee.rst. diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 70e9cc2ee96b..e8840a82b983 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -241,11 +241,23 @@ struct optee_msg_arg { * 384fb3e0-e7f8-11e3-af63-0002a5d5c51b. * Represented in 4 32-bit words in OPTEE_MSG_UID_0, OPTEE_MSG_UID_1, * OPTEE_MSG_UID_2, OPTEE_MSG_UID_3. + * + * In the case where the OP-TEE image is loaded by the kernel, this will + * initially return an alternate UID to reflect that we are communicating with + * the TF-A image loading service at that time instead of OP-TEE. That UID is: + * a3fbeab1-1246-315d-c7c4-06b9c03cbea4. + * Represented in 4 32-bit words in OPTEE_MSG_IMAGE_LOAD_UID_0, + * OPTEE_MSG_IMAGE_LOAD_UID_1, OPTEE_MSG_IMAGE_LOAD_UID_2, + * OPTEE_MSG_IMAGE_LOAD_UID_3. */ #define OPTEE_MSG_UID_0 0x384fb3e0 #define OPTEE_MSG_UID_1 0xe7f811e3 #define OPTEE_MSG_UID_2 0xaf630002 #define OPTEE_MSG_UID_3 0xa5d5c51b +#define OPTEE_MSG_IMAGE_LOAD_UID_0 0xa3fbeab1 +#define OPTEE_MSG_IMAGE_LOAD_UID_1 0x1246315d +#define OPTEE_MSG_IMAGE_LOAD_UID_2 0xc7c406b9 +#define OPTEE_MSG_IMAGE_LOAD_UID_3 0xc03cbea4 #define OPTEE_MSG_FUNCID_CALLS_UID 0xFF01 /* diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h index 73b5e7760d10..7d9fa426505b 100644 --- a/drivers/tee/optee/optee_smc.h +++ b/drivers/tee/optee/optee_smc.h @@ -104,6 +104,30 @@ struct optee_smc_call_get_os_revision_result { unsigned long reserved1; }; +/* + * Load Trusted OS from optee/tee.bin in the Linux firmware. + * + * WARNING: Use this cautiously as it could lead to insecure loading of the + * Trusted OS. + * This SMC instructs EL3 to load a binary and execute it as the Trusted OS. + * + * Call register usage: + * a0 SMC Function ID, OPTEE_SMC_CALL_LOAD_IMAGE + * a1 Upper 32bit of a 64bit size for the payload + * a2 Lower 32bit of a 64bit size for the payload + * a3 Upper 32bit of the physical address for the payload + * a4 Lower 32bit of the physical address for the payload + * + * The payload is in the OP-TEE image format. + * + * Returns result in a0, 0 on success and an error code otherwise. + */ +#define OPTEE_SMC_FUNCID_LOAD_IMAGE 2 +#define OPTEE_SMC_CALL_LOAD_IMAGE \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_TRUSTED_OS_END, \ + OPTEE_SMC_FUNCID_LOAD_IMAGE) + /* * Call with struct optee_msg_arg as argument * diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c index a1c1fa1a9c28..00b6b69b6f79 100644 --- a/drivers/tee/optee/smc_abi.c +++ b/drivers/tee/optee/smc_abi.c @@ -8,9 +8,11 @@ #include <linux/arm-smccc.h> #include <linux/errno.h> +#include <linux/firmware.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/irqdomain.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/of.h> @@ -1149,6 +1151,22 @@ static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn) return false; } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE +static bool optee_msg_api_uid_is_optee_image_load(optee_invoke_fn *invoke_fn) +{ + struct arm_smccc_res res; + + invoke_fn(OPTEE_SMC_CALLS_UID, 0, 0, 0, 0, 0, 0, 0, &res); + + if (res.a0 == OPTEE_MSG_IMAGE_LOAD_UID_0 && + res.a1 == OPTEE_MSG_IMAGE_LOAD_UID_1 && + res.a2 == OPTEE_MSG_IMAGE_LOAD_UID_2 && + res.a3 == OPTEE_MSG_IMAGE_LOAD_UID_3) + return true; + return false; +} +#endif + static void optee_msg_get_os_revision(optee_invoke_fn *invoke_fn) { union { @@ -1354,6 +1372,81 @@ static void optee_shutdown(struct platform_device *pdev) optee_disable_shm_cache(optee); } +#ifdef CONFIG_OPTEE_INSECURE_LOAD_IMAGE + +#define OPTEE_FW_IMAGE "optee/tee.bin" + +static int optee_load_fw(struct platform_device *pdev, + optee_invoke_fn *invoke_fn) +{ + const struct firmware *fw = NULL; + struct arm_smccc_res res; + phys_addr_t data_pa; + u8 *data_buf = NULL; + u64 data_size; + u32 data_pa_high, data_pa_low; + u32 data_size_high, data_size_low; + int rc; + + if (!optee_msg_api_uid_is_optee_image_load(invoke_fn)) + return 0; + + rc = request_firmware(&fw, OPTEE_FW_IMAGE, &pdev->dev); + if (rc) { + /* + * The firmware in the rootfs will not be accessible until we + * are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until + * that point. + */ + if (system_state < SYSTEM_RUNNING) + return -EPROBE_DEFER; + goto fw_err; + } + + data_size = fw->size; + /* + * This uses the GFP_DMA flag to ensure we are allocated memory in the + * 32-bit space since TF-A cannot map memory beyond the 32-bit boundary. + */ + data_buf = kmalloc(fw->size, GFP_KERNEL | GFP_DMA); + if (!data_buf) { + rc = -ENOMEM; + goto fw_err; + } + memcpy(data_buf, fw->data, fw->size); + data_pa = virt_to_phys(data_buf); + reg_pair_from_64(&data_pa_high, &data_pa_low, data_pa); + reg_pair_from_64(&data_size_high, &data_size_low, data_size); + goto fw_load; + +fw_err: + pr_warn("image loading failed\n"); + data_pa_high = data_pa_low = data_size_high = data_size_low = 0; + +fw_load: + /* + * Always invoke the SMC, even if loading the image fails, to indicate + * to EL3 that we have passed the point where it should allow invoking + * this SMC. + */ + pr_warn("OP-TEE image loaded from kernel, this can be insecure"); + invoke_fn(OPTEE_SMC_CALL_LOAD_IMAGE, data_size_high, data_size_low, + data_pa_high, data_pa_low, 0, 0, 0, &res); + if (!rc) + rc = res.a0; + if (fw) + release_firmware(fw); + kfree(data_buf); + + return rc; +} +#else +static inline int optee_load_fw(struct platform_device *__unused1, + optee_invoke_fn *__unused2) { + return 0; +} +#endif + static int optee_probe(struct platform_device *pdev) { optee_invoke_fn *invoke_fn; @@ -1372,6 +1465,10 @@ static int optee_probe(struct platform_device *pdev) if (IS_ERR(invoke_fn)) return PTR_ERR(invoke_fn); + rc = optee_load_fw(pdev, invoke_fn); + if (rc) + return rc; + if (!optee_msg_api_uid_is_optee_api(invoke_fn)) { pr_warn("api uid mismatch\n"); return -EINVAL; -- 2.40.0.rc1.284.g88254d51c5-goog

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OP-TEE