- OP-TEE - lists.trustedfirmware.org

[PATCH v12] 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> Reviewed-by: Sumit Garg <sumit.garg(a)linaro.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v12: - Fixed checkpatch strict issues Changes in v11: - Fixed typo in tee.rst documentation 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 | 137 ++++++++++++++++++++++++++++++++++ 5 files changed, 231 insertions(+) diff --git a/Documentation/staging/tee.rst b/Documentation/staging/tee.rst index 498343c7ab08..b11e9053bc99 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. + 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 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..6e1f023d50c6 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 +1373,120 @@ 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 = 0; + data_pa_low = 0; + data_size_high = 0; + 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 +1505,10 @@ 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; -- 2.40.0.348.gf938b09366-goog

3 years, 2 months

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[GIT PULL] TEE fix for v6.3

by Jens Wiklander

Hello arm-soc maintainers, Please pull this small fix of a call to virt_to_page() in the TEE subsystem. 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/tee-fix-for-v6.3 for you to fetch changes up to 8671133082176d1388e20ac33d61cf7e3b05adf5: tee: Pass a pointer to virt_to_page() (2023-03-30 08:34:52 +0200) ---------------------------------------------------------------- Add explicit cast to (void *) for virt_to_page() argument ---------------------------------------------------------------- Linus Walleij (1): tee: Pass a pointer to virt_to_page() drivers/tee/tee_shm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

3 years, 2 months

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[PATCH] tee: Pass a pointer to virt_to_page()

by Linus Walleij

Like the other calls in this function virt_to_page() expects a pointer, not an integer. However since many architectures implement virt_to_pfn() as a macro, this function becomes polymorphic and accepts both a (unsigned long) and a (void *). Fix this up with an explicit cast. Signed-off-by: Linus Walleij <linus.walleij(a)linaro.org> --- drivers/tee/tee_shm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index b1c6231defad..673cf0359494 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -32,7 +32,7 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count, is_kmap_addr((void *)start))) return -EINVAL; - page = virt_to_page(start); + page = virt_to_page((void *)start); for (n = 0; n < page_count; n++) { pages[n] = page + n; get_page(pages[n]); -- 2.34.1

3 years, 2 months

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[PATCH v6 1/2] dt-bindings: optee driver interrupt can be a per-cpu interrupt

by Etienne Carriere

Explicit in optee firmware device tree bindings that the interrupt used by optee driver for async notification can be a peripheral interrupt or a per-cpu interrupt. Signed-off-by: Etienne Carriere <etienne.carriere(a)linaro.org> --- No change since v5 No change since v4 Changes since v3: - Patch added in this v4 to address review comments. --- .../devicetree/bindings/arm/firmware/linaro,optee-tz.yaml | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml index d4dc0749f9fd..5d033570b57b 100644 --- a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml +++ b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml @@ -28,7 +28,8 @@ properties: maxItems: 1 description: | This interrupt which is used to signal an event by the secure world - software is expected to be edge-triggered. + software is expected to be either a per-cpu interrupt or an + edge-triggered peripheral interrupt. method: enum: [smc, hvc] -- 2.25.1

3 years, 2 months

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[PATCH][next] optee: Fix spelling mistake "Unuspported" -> "Unsupported"

by Colin Ian King

There is a spelling mistake in a #error message. Fix it. Signed-off-by: Colin Ian King <colin.i.king(a)gmail.com> --- 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 } -- 2.30.2

3 years, 2 months

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[Hafnium] Boot arguments for S-EL1 with SPMC at S-EL2

by 梅建强(禹夜)

Hi, Olivier, Whether Boot Information Blob is a file similar to manifest.dtb or sp.pkg? How do I generate this blob? Does it need to be packaged into atf firmware at compile phase？ Thanks. Regards, Yuye. ------------------------------------------------------------------ 发件人：Olivier Deprez <Olivier.Deprez(a)arm.com> 发送时间：2023年3月21日(星期二) 22:37 收件人：Jens Wiklander <jens.wiklander(a)linaro.org> 抄　送：hafnium(a)lists.trustedfirmware.org <hafnium(a)lists.trustedfirmware.org>; OP-TEE TrustedFirmware <op-tee(a)lists.trustedfirmware.org> 主　题：Re: [Hafnium] Boot arguments for S-EL1 with SPMC at S-EL2 Hi Jens, See comments inline [OD]. Regards, Olivier. ________________________________ From: Jens Wiklander via Hafnium <hafnium(a)lists.trustedfirmware.org> Sent: 21 March 2023 09:30 To: Olivier Deprez <Olivier.Deprez(a)arm.com> Cc: hafnium(a)lists.trustedfirmware.org <hafnium(a)lists.trustedfirmware.org>; OP-TEE TrustedFirmware <op-tee(a)lists.trustedfirmware.org> Subject: [Hafnium] Boot arguments for S-EL1 with SPMC at S-EL2 Hi Olivier, I'm trying to implement a relocatable OP-TEE binary so it can be loaded at different physical addresses without the need to recompile it. This means that in the case with Hafnium when changing "load-address" or "entrypoint-offset" in the OP-TEE SP manifest there's no need to recompile OP-TEE. For this to work OP-TEE must be able to figure out which memory range it's supposed to reside in. [OD] Fair enough, I believe that would conflate into some generic PIE support? I can see how this helps with the multi OP-TEE instances use case, perhaps? Currently, OP-TEE knows the entry point address from PC and "memory size" from X0. However, the "memory size" is from the "load-address" so "entrypoint-offset" must be subtracted from PC in order to know the allocated memory range. Do you have ideas on how OP-TEE at runtime can determine the allocated memory range? [OD] The standard way would be to use the FF-A boot protocol e.g. if you add this to OP-TEE's SP manifest: + /* Boot protocol */ + gp-register-num = <0x0>; + + /* Boot Info */ + boot-info { + compatible = "arm,ffa-manifest-boot-info"; + ffa_manifest; + }; See https://trustedfirmware-a.readthedocs.io/en/latest/components/secure-partit… <https://trustedfirmware-a.readthedocs.io/en/latest/components/secure-partit… > At SP entry, x0 contains the address of a 'Boot Information Blob' (FF-A v1.1 REL0 section 5.4.2) starting with a Boot Information Header (Table 5.9). The SP manifest DT address can be extracted from a Boot Information Descriptor (Table 5.8). Eventually the SP is able to parse its own SP manifest, into which it finds FF-A standard fields (load-address...) in addition to any impdef field added. Note the partition size is not standarded (it should probably be), so for starters you can add your own memsize field. There is some sample usage in TF-a-tests: https://git.trustedfirmware.org/TF-A/tf-a-tests.git/tree/spm/cactus/cactus_… <https://git.trustedfirmware.org/TF-A/tf-a-tests.git/tree/spm/cactus/cactus_… > and also in context of EDKII/StMM: https://github.com/odeprez/edk2/commit/7066c913cb227056d68ea99de5e92f2067fe… <https://github.com/odeprez/edk2/commit/7066c913cb227056d68ea99de5e92f2067fe… > Thanks, Jens -- Hafnium mailing list -- hafnium(a)lists.trustedfirmware.org To unsubscribe send an email to hafnium-leave(a)lists.trustedfirmware.org

3 years, 2 months

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[PATCH v11] 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> Reviewed-by: Sumit Garg <sumit.garg(a)linaro.org> Signed-off-by: Jeffrey Kardatzke <jkardatzke(a)google.com> --- Changes in v11: - Fixed typo in tee.rst documentation 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..b11e9053bc99 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. + 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 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

3 years, 2 months

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Linaro OP-TEE Contribution (LOC) monthly meeting March 28

by Jens Wiklander

Hi, It's soon time for another LOC monthly meeting. For time and connection details see the calendar at https://www.trustedfirmware.org/meetings/ If you have any topics you'd like to discuss, please let us know and we can schedule them. Thanks, Jens

3 years, 2 months

1
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load optee at 36bit address

by 梅建强(禹夜)

Hi, experts, We seem to have solved the problem. This problem is not caused by the load_address of optee, but by the security space configured in the ATF. It seems that the security space we have configured is too large. And why will it causes the problem needs to be further identified. Regards, Yuye. ------------------------------------------------------------------ 发件人：梅建强(禹夜) <meijianqiang.mjq(a)alibaba-inc.com> 发送时间：2023年3月22日(星期三) 11:50 收件人：Olivier Deprez <Olivier.Deprez(a)arm.com>; Jens Wiklander <jens.wiklander(a)linaro.org> 抄　送：hafnium <hafnium(a)lists.trustedfirmware.org>; op-tee <op-tee(a)lists.trustedfirmware.org> 主　题：load optee at 36bit address Hi, experts, We are currently moving optee to a 36bit address to boot with environment that hafnium runs at sel2 as spmc and optee runs at sel1 as sp. Now we have moved hafnium to 0x880000000 and run successfully. Then we tried moving optee to a 36bit address (0x89000000) as well. Although hafnium and optee were successfully initialized on the primary cpu, psci_cpu_on does not seem to be entered into when the secondary cpu is started. The error is as follows: https://github.com/OP-TEE/optee_os/issues/5895 <https://github.com/OP-TEE/optee_os/issues/5895 > Is there any difference between the two cases where hafnium and optee initialize the secondary cpu with different load_address? The log print shows that the secondary cpu has not entered hafnium. Could Hafnium be affected by the 36bit address when dealing with psci related transactions? Regards, Yuye.

3 years, 2 months

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load optee at 36bit address

by 梅建强(禹夜)

Hi, experts, We are currently moving optee to a 36bit address to boot with environment that hafnium runs at sel2 as spmc and optee runs at sel1 as sp. Now we have moved hafnium to 0x880000000 and run successfully. Then we tried moving optee to a 36bit address (0x89000000) as well. Although hafnium and optee were successfully initialized on the primary cpu, psci_cpu_on does not seem to be entered into when the secondary cpu is started. The error is as follows: https://github.com/OP-TEE/optee_os/issues/5895 <https://github.com/OP-TEE/optee_os/issues/5895 > Is there any difference between the two cases where hafnium and optee initialize the secondary cpu with different load_address? The log print shows that the secondary cpu has not entered hafnium. Could Hafnium be affected by the 36bit address when dealing with psci related transactions? Regards, Yuye.

3 years, 2 months

1
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