[PATCH v3 3/3] efi: Add tee-based EFI variable driver
Masahisa Kojima
masahisa.kojima at linaro.org
Tue May 23 01:36:46 PDT 2023
Hi Jens,
On Mon, 8 May 2023 at 18:45, Jens Wiklander <jens.wiklander at linaro.org> wrote:
>
> Hi,
>
> On Wed, Feb 22, 2023 at 6:40 AM Masahisa Kojima
> <masahisa.kojima at linaro.org> wrote:
> >
> > When the flash is not owned by the non-secure world, accessing the EFI
> > variables is straightforward and done via EFI Runtime Variable Services.
> > In this case, critical variables for system integrity and security
> > are normally stored in the dedicated secure storage and only accessible
> > from the secure world.
> >
> > On the other hand, the small embedded devices don't have the special
> > dedicated secure storage. The eMMC device with an RPMB partition is
> > becoming more common, we can use an RPMB partition to store the
> > EFI Variables.
> >
> > 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
> > TEE(OP-TEE in this case), 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 TEE and StandaloneMM.
> >
> > So let's add the kernel functions needed.
> >
> > This feature is implemented as a kernel module.
> > StMM PTA has TA_FLAG_DEVICE_ENUM_SUPP flag when registered to OP-TEE
> > so that this tee_stmm_efi module is probed after tee-supplicant starts,
> > since "SetVariable" EFI Runtime Variable Service requires to
> > interact with tee-supplicant.
> >
> > Co-developed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> > ---
> > drivers/firmware/efi/Kconfig | 15 +
> > drivers/firmware/efi/Makefile | 1 +
> > drivers/firmware/efi/stmm/mm_communication.h | 249 ++++++++
> > drivers/firmware/efi/stmm/tee_stmm_efi.c | 626 +++++++++++++++++++
> > 4 files changed, 891 insertions(+)
> > create mode 100644 drivers/firmware/efi/stmm/mm_communication.h
> > create mode 100644 drivers/firmware/efi/stmm/tee_stmm_efi.c
> >
> > diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> > index 043ca31c114e..aa38089d1e4a 100644
> > --- a/drivers/firmware/efi/Kconfig
> > +++ b/drivers/firmware/efi/Kconfig
> > @@ -287,3 +287,18 @@ config UEFI_CPER_X86
> > bool
> > depends on UEFI_CPER && X86
> > default y
> > +
> > +config TEE_STMM_EFI
> > + tristate "TEE based EFI runtime variable service driver"
> > + depends on EFI && OPTEE && !EFI_VARS_PSTORE
> > + help
> > + Select this config option if TEE is compiled to include StandAloneMM
> > + as a separate secure partition it has the ability to check and store
> > + EFI variables on an RPMB or any other non-volatile medium used by
> > + StandAloneMM.
> > +
> > + Enabling this will change the EFI runtime services from the firmware
> > + provided functions to TEE calls.
> > +
> > + To compile this driver as a module, choose M here: the module
> > + will be called tee_stmm_efi.
> > diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> > index b51f2a4c821e..2ca8ee6ab490 100644
> > --- a/drivers/firmware/efi/Makefile
> > +++ b/drivers/firmware/efi/Makefile
> > @@ -41,3 +41,4 @@ obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
> > obj-$(CONFIG_EFI_EARLYCON) += earlycon.o
> > obj-$(CONFIG_UEFI_CPER_ARM) += cper-arm.o
> > obj-$(CONFIG_UEFI_CPER_X86) += cper-x86.o
> > +obj-$(CONFIG_TEE_STMM_EFI) += stmm/tee_stmm_efi.o
> > diff --git a/drivers/firmware/efi/stmm/mm_communication.h b/drivers/firmware/efi/stmm/mm_communication.h
> > new file mode 100644
> > index 000000000000..a7fa6723d56e
> > --- /dev/null
> > +++ b/drivers/firmware/efi/stmm/mm_communication.h
> > @@ -0,0 +1,249 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * Headers for EFI variable service via StandAloneMM, EDK2 application running
> > + * in OP-TEE
> > + *
> > + * Copyright (c) 2017, Intel Corporation. All rights reserved.
> > + * Copyright (C) 2020 Linaro Ltd.
> > + */
> > +
> > +#ifndef _MM_COMMUNICATION_H_
> > +#define _MM_COMMUNICATION_H_
> > +
> > +/*
> > + * Interface to the pseudo Trusted Application (TA), which provides a
> > + * communication channel with the Standalone MM (Management Mode)
> > + * Secure Partition running at Secure-EL0
> > + */
> > +
> > +#define PTA_STMM_CMD_COMMUNICATE 0
> > +
> > +/* OP-TEE is using big endian GUIDs while UEFI uses little endian ones */
> > +#define PTA_STMM_UUID \
> > + UUID_INIT(0xed32d533, 0x99e6, 0x4209, \
> > + 0x9c, 0xc0, 0x2d, 0x72, 0xcd, 0xd9, 0x98, 0xa7)
> > +
> > +#define EFI_MM_VARIABLE_GUID \
> > + EFI_GUID(0xed32d533, 0x99e6, 0x4209, \
> > + 0x9c, 0xc0, 0x2d, 0x72, 0xcd, 0xd9, 0x98, 0xa7)
> > +
> > +/* Defined in EDK2 MdePkg/Include/Protocol/MmCommunication.h */
> > +
> > +/**
> > + * struct efi_mm_communicate_header - Header used for SMM variable communication
> > +
> > + * @header_guid: header use for disambiguation of content
> > + * @message_len: length of the message. Does not include the size of the
> > + * header
> > + * @data: payload of the message
> > + *
> > + * Defined in EDK2 as EFI_MM_COMMUNICATE_HEADER.
> > + * To avoid confusion in interpreting frames, the communication buffer should
> > + * always begin with efi_mm_communicate_header.
> > + */
> > +struct efi_mm_communicate_header {
> > + efi_guid_t header_guid;
> > + size_t message_len;
> > + u8 data[];
> > +} __packed;
> > +
> > +#define MM_COMMUNICATE_HEADER_SIZE \
> > + (sizeof(struct efi_mm_communicate_header))
> > +
> > +/* Defined in EDK2 ArmPkg/Include/IndustryStandard/ArmMmSvc.h */
> > +
> > +/* SPM return error codes */
> > +#define ARM_SVC_SPM_RET_SUCCESS 0
> > +#define ARM_SVC_SPM_RET_NOT_SUPPORTED -1
> > +#define ARM_SVC_SPM_RET_INVALID_PARAMS -2
> > +#define ARM_SVC_SPM_RET_DENIED -3
> > +#define ARM_SVC_SPM_RET_NO_MEMORY -5
> > +
> > +/* Defined in EDK2 MdeModulePkg/Include/Guid/SmmVariableCommon.h */
> > +
> > +#define SMM_VARIABLE_FUNCTION_GET_VARIABLE 1
> > +/*
> > + * The payload for this function is
> > + * SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME 2
> > +/*
> > + * The payload for this function is SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_SET_VARIABLE 3
> > +/*
> > + * The payload for this function is
> > + * SMM_VARIABLE_COMMUNICATE_QUERY_VARIABLE_INFO.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO 4
> > +/*
> > + * It is a notify event, no extra payload for this function.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_READY_TO_BOOT 5
> > +/*
> > + * It is a notify event, no extra payload for this function.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_EXIT_BOOT_SERVICE 6
> > +/*
> > + * The payload for this function is VARIABLE_INFO_ENTRY.
> > + * The GUID in EFI_SMM_COMMUNICATE_HEADER is gEfiSmmVariableProtocolGuid.
> > + */
> > +#define SMM_VARIABLE_FUNCTION_GET_STATISTICS 7
> > +/*
> > + * The payload for this function is SMM_VARIABLE_COMMUNICATE_LOCK_VARIABLE
> > + */
> > +#define SMM_VARIABLE_FUNCTION_LOCK_VARIABLE 8
> > +
> > +#define SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET 9
> > +
> > +#define SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET 10
> > +
> > +#define SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE 11
> > +/*
> > + * The payload for this function is
> > + * SMM_VARIABLE_COMMUNICATE_RUNTIME_VARIABLE_CACHE_CONTEXT
> > + */
> > +#define SMM_VARIABLE_FUNCTION_INIT_RUNTIME_VARIABLE_CACHE_CONTEXT 12
> > +
> > +#define SMM_VARIABLE_FUNCTION_SYNC_RUNTIME_CACHE 13
> > +/*
> > + * The payload for this function is
> > + * SMM_VARIABLE_COMMUNICATE_GET_RUNTIME_CACHE_INFO
> > + */
> > +#define SMM_VARIABLE_FUNCTION_GET_RUNTIME_CACHE_INFO 14
> > +
> > +/**
> > + * struct smm_variable_communicate_header - Used for SMM variable communication
> > +
> > + * @function: function to call in Smm.
> > + * @ret_status: return status
> > + * @data: payload
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_HEADER.
> > + */
> > +struct smm_variable_communicate_header {
> > + size_t function;
> > + efi_status_t ret_status;
> > + u8 data[];
> > +};
> > +
> > +#define MM_VARIABLE_COMMUNICATE_SIZE \
> > + (sizeof(struct smm_variable_communicate_header))
> > +
> > +/**
> > + * struct smm_variable_access - Used to communicate with StMM by
> > + * SetVariable and GetVariable.
> > +
> > + * @guid: vendor GUID
> > + * @data_size: size of EFI variable data
> > + * @name_size: size of EFI name
> > + * @attr: attributes
> > + * @name: variable name
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE.
> > + *
> > + */
> > +struct smm_variable_access {
> > + efi_guid_t guid;
> > + size_t data_size;
> > + size_t name_size;
> > + u32 attr;
> > + u16 name[];
> > +};
> > +
> > +#define MM_VARIABLE_ACCESS_HEADER_SIZE \
> > + (sizeof(struct smm_variable_access))
> > +/**
> > + * struct smm_variable_payload_size - Used to get the max allowed
> > + * payload used in StMM.
> > + *
> > + * @size: size to fill in
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_GET_PAYLOAD_SIZE.
> > + *
> > + */
> > +struct smm_variable_payload_size {
> > + size_t size;
> > +};
> > +
> > +/**
> > + * struct smm_variable_getnext - Used to communicate with StMM for
> > + * GetNextVariableName.
> > + *
> > + * @guid: vendor GUID
> > + * @name_size: size of the name of the variable
> > + * @name: variable name
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME.
> > + */
> > +struct smm_variable_getnext {
> > + efi_guid_t guid;
> > + size_t name_size;
> > + u16 name[];
> > +};
> > +
> > +#define MM_VARIABLE_GET_NEXT_HEADER_SIZE \
> > + (sizeof(struct smm_variable_getnext))
> > +
> > +/**
> > + * struct smm_variable_query_info - Used to communicate with StMM for
> > + * QueryVariableInfo.
> > + *
> > + * @max_variable_storage: max available storage
> > + * @remaining_variable_storage: remaining available storage
> > + * @max_variable_size: max variable supported size
> > + * @attr: attributes to query storage for
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_QUERY_VARIABLE_INFO.
> > + */
> > +struct smm_variable_query_info {
> > + u64 max_variable_storage;
> > + u64 remaining_variable_storage;
> > + u64 max_variable_size;
> > + u32 attr;
> > +};
> > +
> > +#define VAR_CHECK_VARIABLE_PROPERTY_REVISION 0x0001
> > +#define VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY BIT(0)
> > +/**
> > + * struct var_check_property - Used to store variable properties in StMM
> > + *
> > + * @revision: magic revision number for variable property checking
> > + * @property: properties mask for the variable used in StMM.
> > + * Currently RO flag is supported
> > + * @attributes: variable attributes used in StMM checking when properties
> > + * for a variable are enabled
> > + * @minsize: minimum allowed size for variable payload checked against
> > + * smm_variable_access->datasize in StMM
> > + * @maxsize: maximum allowed size for variable payload checked against
> > + * smm_variable_access->datasize in StMM
> > + *
> > + * Defined in EDK2 as VAR_CHECK_VARIABLE_PROPERTY.
> > + */
> > +struct var_check_property {
> > + u16 revision;
> > + u16 property;
> > + u32 attributes;
> > + size_t minsize;
> > + size_t maxsize;
> > +};
> > +
> > +/**
> > + * struct smm_variable_var_check_property - Used to communicate variable
> > + * properties with StMM
> > + *
> > + * @guid: vendor GUID
> > + * @name_size: size of EFI name
> > + * @property: variable properties struct
> > + * @name: variable name
> > + *
> > + * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_VAR_CHECK_VARIABLE_PROPERTY.
> > + */
> > +struct smm_variable_var_check_property {
> > + efi_guid_t guid;
> > + size_t name_size;
> > + struct var_check_property property;
> > + u16 name[];
> > +};
> > +
> > +#endif /* _MM_COMMUNICATION_H_ */
> > diff --git a/drivers/firmware/efi/stmm/tee_stmm_efi.c b/drivers/firmware/efi/stmm/tee_stmm_efi.c
> > new file mode 100644
> > index 000000000000..da4bc447f515
> > --- /dev/null
> > +++ b/drivers/firmware/efi/stmm/tee_stmm_efi.c
> > @@ -0,0 +1,626 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * EFI variable service via TEE
> > + *
> > + * Copyright (C) 2022 Linaro
> > + */
> > +
> > +#include <linux/efi.h>
> > +#include <linux/kernel.h>
> > +#include <linux/slab.h>
> > +#include <linux/tee.h>
> > +#include <linux/tee_drv.h>
> > +#include <linux/ucs2_string.h>
> > +#include "mm_communication.h"
> > +
> > +static struct efivars tee_efivars;
> > +static struct efivar_operations tee_efivar_ops;
> > +
> > +static size_t max_buffer_size; /* comm + var + func + data */
> > +static size_t max_payload_size; /* func + data */
> > +
> > +struct tee_stmm_efi_private {
> > + struct tee_context *ctx;
> > + u32 session;
> > + struct device *dev;
> > +};
> > +
> > +static struct tee_stmm_efi_private pvt_data;
> > +
> > +/* UUID of the stmm PTA */
> > +static const struct tee_client_device_id tee_stmm_efi_id_table[] = {
> > + {PTA_STMM_UUID},
> > + {}
> > +};
> > +
> > +static int tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
> > +{
> > + /* currently only OP-TEE is supported as a communication path */
> > + if (ver->impl_id == TEE_IMPL_ID_OPTEE)
> > + return 1;
> > + else
> > + return 0;
> > +}
> > +
> > +/**
> > + * tee_mm_communicate() - Pass a buffer to StandaloneMM running in TEE
> > + *
> > + * @comm_buf: locally allocated communication buffer
> > + * @dsize: buffer size
> > + * Return: status code
> > + */
> > +static efi_status_t tee_mm_communicate(void *comm_buf, size_t dsize)
> > +{
> > + size_t buf_size;
> > + efi_status_t ret;
> > + struct efi_mm_communicate_header *mm_hdr;
> > + struct tee_ioctl_invoke_arg arg;
> > + struct tee_param param[4];
> > + struct tee_shm *shm = NULL;
> > + int rc;
> > +
> > + if (!comm_buf)
> > + return EFI_INVALID_PARAMETER;
> > +
> > + mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
> > + buf_size = mm_hdr->message_len + sizeof(efi_guid_t) + sizeof(size_t);
> > +
> > + if (dsize != buf_size)
> > + return EFI_INVALID_PARAMETER;
>
> I don't see why tee_mm_communicate() should need to look inside the
> communication buffer. If we need this sanity check it's better done in
> mm_communicate() below.
I think this check is redundant and we could remove it.
>
> > +
> > + shm = tee_shm_register_kernel_buf(pvt_data.ctx, comm_buf, buf_size);
> > + if (IS_ERR(shm)) {
> > + dev_err(pvt_data.dev, "Unable to register shared memory\n");
> > + return EFI_UNSUPPORTED;
> > + }
> > +
> > + memset(&arg, 0, sizeof(arg));
> > + arg.func = PTA_STMM_CMD_COMMUNICATE;
> > + arg.session = pvt_data.session;
> > + arg.num_params = 4;
> > +
> > + memset(param, 0, sizeof(param));
> > + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT;
> > + param[0].u.memref.size = buf_size;
> > + param[0].u.memref.shm = shm;
> > + param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> > + param[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
> > + param[3].attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
> > +
> > + rc = tee_client_invoke_func(pvt_data.ctx, &arg, param);
> > + tee_shm_free(shm);
> > +
> > + if (rc < 0 || arg.ret != 0) {
> > + dev_err(pvt_data.dev,
> > + "PTA_STMM_CMD_COMMUNICATE invoke error: 0x%x\n", arg.ret);
> > + return EFI_DEVICE_ERROR;
> > + }
> > +
> > + switch (param[1].u.value.a) {
> > + case ARM_SVC_SPM_RET_SUCCESS:
> > + ret = EFI_SUCCESS;
> > + break;
> > +
> > + case ARM_SVC_SPM_RET_INVALID_PARAMS:
> > + ret = EFI_INVALID_PARAMETER;
> > + break;
> > +
> > + case ARM_SVC_SPM_RET_DENIED:
> > + ret = EFI_ACCESS_DENIED;
> > + break;
> > +
> > + case ARM_SVC_SPM_RET_NO_MEMORY:
> > + ret = EFI_OUT_OF_RESOURCES;
> > + break;
> > +
> > + default:
> > + ret = EFI_ACCESS_DENIED;
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * mm_communicate() - Adjust the communication buffer to StandAlonneMM and send
> > + * it to TEE
> > + *
> > + * @comm_buf: locally allocated communication buffer
> > + * @dsize: buffer size
>
> This is confusing, comm_buf points to the mm header, while dsize tells
> the payload size. So the arguments to this function aren't the normal
> buffer pointer and length tuple. When looking at how this function is
> called it makes sense, but we should clarify the relationship here.
I will rename dsize argument to payload_size, then add some comments
for comm_buf.
>
> > + * Return: status code
> > + */
> > +static efi_status_t mm_communicate(u8 *comm_buf, size_t dsize)
> > +{
> > + efi_status_t ret;
> > + struct efi_mm_communicate_header *mm_hdr;
> > + struct smm_variable_communicate_header *var_hdr;
> > +
> > + dsize += MM_COMMUNICATE_HEADER_SIZE + MM_VARIABLE_COMMUNICATE_SIZE;
> > + mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
> > + var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
> > +
> > + ret = tee_mm_communicate(comm_buf, dsize);
> > + if (ret != EFI_SUCCESS) {
> > + dev_err(pvt_data.dev, "%s failed!\n", __func__);
> > + return ret;
> > + }
> > +
> > + return var_hdr->ret_status;
> > +}
> > +
> > +/**
> > + * setup_mm_hdr() - Allocate a buffer for StandAloneMM and initialize the
> > + * header data.
> > + *
> > + * @dptr: pointer address of the corresponding StandAloneMM
> > + * function
> > + * @payload_size: buffer size
> > + * @func: standAloneMM function number
> > + * @ret: EFI return code
> > + * Return: buffer or NULL
> > + */
> > +static u8 *setup_mm_hdr(void **dptr, size_t payload_size, size_t func,
> > + efi_status_t *ret)
> > +{
> > + const efi_guid_t mm_var_guid = EFI_MM_VARIABLE_GUID;
> > + struct efi_mm_communicate_header *mm_hdr;
> > + struct smm_variable_communicate_header *var_hdr;
> > + u8 *comm_buf;
> > +
> > + /* In the init function we initialize max_buffer_size with
> > + * get_max_payload(). So skip the test if max_buffer_size is initialized
> > + * StandAloneMM will perform similar checks and drop the buffer if it's
> > + * too long
> > + */
> > + if (max_buffer_size &&
> > + max_buffer_size < (MM_COMMUNICATE_HEADER_SIZE +
> > + MM_VARIABLE_COMMUNICATE_SIZE + payload_size)) {
> > + *ret = EFI_INVALID_PARAMETER;
> > + return NULL;
> > + }
> > +
> > + comm_buf = kzalloc(MM_COMMUNICATE_HEADER_SIZE +
> > + MM_VARIABLE_COMMUNICATE_SIZE + payload_size,
> > + GFP_KERNEL);
> > + if (!comm_buf) {
> > + *ret = EFI_OUT_OF_RESOURCES;
> > + return NULL;
> > + }
> > +
> > + mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
> > + memcpy(&mm_hdr->header_guid, &mm_var_guid, sizeof(mm_hdr->header_guid));
> > + mm_hdr->message_len = MM_VARIABLE_COMMUNICATE_SIZE + payload_size;
> > +
> > + var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
> > + var_hdr->function = func;
> > + if (dptr)
> > + *dptr = var_hdr->data;
> > + *ret = EFI_SUCCESS;
> > +
> > + return comm_buf;
> > +}
> > +
> > +/**
> > + * get_max_payload() - Get variable payload size from StandAloneMM.
> > + *
> > + * @size: size of the variable in storage
> > + * Return: status code
> > + */
> > +static efi_status_t get_max_payload(size_t *size)
> > +{
> > + struct smm_variable_payload_size *var_payload = NULL;
> > + size_t payload_size;
> > + u8 *comm_buf = NULL;
> > + efi_status_t ret;
> > +
> > + if (!size) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + payload_size = sizeof(*var_payload);
> > + comm_buf = setup_mm_hdr((void **)&var_payload, payload_size,
> > + SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE, &ret);
>
> The (void **) cast is a bit ugly. If instead the payload buffer was
> returned in the return value and &comm_buf was the first argument we
> wouldn't need to cast at all.
Thank you, I will fix it.
Sorry for the late reply.
Regards,
Masahisa Kojima
>
> > + if (!comm_buf)
> > + goto out;
> > +
> > + ret = mm_communicate(comm_buf, payload_size);
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > +
> > + /* Make sure the buffer is big enough for storing variables */
> > + if (var_payload->size < MM_VARIABLE_ACCESS_HEADER_SIZE + 0x20) {
> > + ret = EFI_DEVICE_ERROR;
> > + goto out;
> > + }
> > + *size = var_payload->size;
> > + /*
> > + * There seems to be a bug in EDK2 miscalculating the boundaries and
> > + * size checks, so deduct 2 more bytes to fulfill this requirement. Fix
> > + * it up here to ensure backwards compatibility with older versions
> > + * (cf. StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c.
> > + * sizeof (EFI_MM_COMMUNICATE_HEADER) instead the size minus the
> > + * flexible array member).
> > + *
> > + * size is guaranteed to be > 2 due to checks on the beginning.
> > + */
> > + *size -= 2;
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static efi_status_t get_property_int(u16 *name, size_t name_size,
> > + const efi_guid_t *vendor,
> > + struct var_check_property *var_property)
> > +{
> > + struct smm_variable_var_check_property *smm_property;
> > + size_t payload_size;
> > + u8 *comm_buf = NULL;
> > + efi_status_t ret;
> > +
> > + memset(var_property, 0, sizeof(*var_property));
> > + payload_size = sizeof(*smm_property) + name_size;
> > + if (payload_size > max_payload_size) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > + comm_buf = setup_mm_hdr(
> > + (void **)&smm_property, payload_size,
> > + SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET, &ret);
> > + if (!comm_buf)
> > + goto out;
> > +
> > + memcpy(&smm_property->guid, vendor, sizeof(smm_property->guid));
> > + smm_property->name_size = name_size;
> > + memcpy(smm_property->name, name, name_size);
> > +
> > + ret = mm_communicate(comm_buf, payload_size);
> > + /*
> > + * Currently only R/O property is supported in StMM.
> > + * Variables that are not set to R/O will not set the property in StMM
> > + * and the call will return EFI_NOT_FOUND. We are setting the
> > + * properties to 0x0 so checking against that is enough for the
> > + * EFI_NOT_FOUND case.
> > + */
> > + if (ret == EFI_NOT_FOUND)
> > + ret = EFI_SUCCESS;
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > + memcpy(var_property, &smm_property->property, sizeof(*var_property));
> > +
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
> > + u32 *attributes, unsigned long *data_size,
> > + void *data)
> > +{
> > + struct var_check_property var_property;
> > + struct smm_variable_access *var_acc;
> > + size_t payload_size;
> > + size_t name_size;
> > + size_t tmp_dsize;
> > + u8 *comm_buf = NULL;
> > + efi_status_t ret;
> > +
> > + if (!name || !vendor || !data_size) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
> > + if (name_size > max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + /* Trim output buffer size */
> > + tmp_dsize = *data_size;
> > + if (name_size + tmp_dsize >
> > + max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
> > + tmp_dsize = max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE -
> > + name_size;
> > + }
> > +
> > + /* Get communication buffer and initialize header */
> > + payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + tmp_dsize;
> > + comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
> > + SMM_VARIABLE_FUNCTION_GET_VARIABLE, &ret);
> > + if (!comm_buf)
> > + goto out;
> > +
> > + /* Fill in contents */
> > + memcpy(&var_acc->guid, vendor, sizeof(var_acc->guid));
> > + var_acc->data_size = tmp_dsize;
> > + var_acc->name_size = name_size;
> > + var_acc->attr = attributes ? *attributes : 0;
> > + memcpy(var_acc->name, name, name_size);
> > +
> > + /* Communicate */
> > + ret = mm_communicate(comm_buf, payload_size);
> > + if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL)
> > + /* Update with reported data size for trimmed case */
> > + *data_size = var_acc->data_size;
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > +
> > + ret = get_property_int(name, name_size, vendor, &var_property);
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > +
> > + if (attributes)
> > + *attributes = var_acc->attr;
> > +
> > + if (data)
> > + memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
> > + var_acc->data_size);
> > + else
> > + ret = EFI_INVALID_PARAMETER;
> > +
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static efi_status_t tee_get_next_variable(unsigned long *name_size,
> > + efi_char16_t *name, efi_guid_t *guid)
> > +{
> > + struct smm_variable_getnext *var_getnext;
> > + size_t payload_size;
> > + size_t out_name_size;
> > + size_t in_name_size;
> > + u8 *comm_buf = NULL;
> > + efi_status_t ret;
> > +
> > + if (!name_size || !name || !guid) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + out_name_size = *name_size;
> > + in_name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
> > +
> > + if (out_name_size < in_name_size) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + if (in_name_size >
> > + max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + /* Trim output buffer size */
> > + if (out_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
> > + out_name_size =
> > + max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE;
> > +
> > + payload_size = MM_VARIABLE_GET_NEXT_HEADER_SIZE + out_name_size;
> > + comm_buf = setup_mm_hdr((void **)&var_getnext, payload_size,
> > + SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME,
> > + &ret);
> > + if (!comm_buf)
> > + goto out;
> > +
> > + /* Fill in contents */
> > + memcpy(&var_getnext->guid, guid, sizeof(var_getnext->guid));
> > + var_getnext->name_size = out_name_size;
> > + memcpy(var_getnext->name, name, in_name_size);
> > + memset((u8 *)var_getnext->name + in_name_size, 0x0,
> > + out_name_size - in_name_size);
> > +
> > + /* Communicate */
> > + ret = mm_communicate(comm_buf, payload_size);
> > + if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
> > + /* Update with reported data size for trimmed case */
> > + *name_size = var_getnext->name_size;
> > + }
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > +
> > + memcpy(guid, &var_getnext->guid, sizeof(*guid));
> > + memcpy(name, var_getnext->name, var_getnext->name_size);
> > +
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
> > + u32 attributes, unsigned long data_size,
> > + void *data)
> > +{
> > + efi_status_t ret;
> > + struct var_check_property var_property;
> > + struct smm_variable_access *var_acc;
> > + size_t payload_size;
> > + size_t name_size;
> > + u8 *comm_buf = NULL;
> > +
> > + if (!name || name[0] == 0 || !vendor) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > + if (data_size > 0 && !data) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > + /* Check payload size */
> > + name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
> > + payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
> > + if (payload_size > max_payload_size) {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + /*
> > + * Allocate the buffer early, before switching to RW (if needed)
> > + * so we won't need to account for any failures in reading/setting
> > + * the properties, if the allocation fails
> > + */
> > + comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
> > + SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
> > + if (!comm_buf)
> > + goto out;
> > +
> > + /*
> > + * The API has the ability to override RO flags. If no RO check was
> > + * requested switch the variable to RW for the duration of this call
> > + */
> > + ret = get_property_int(name, name_size, vendor, &var_property);
> > + if (ret != EFI_SUCCESS) {
> > + dev_err(pvt_data.dev, "Getting variable property failed\n");
> > + goto out;
> > + }
> > +
> > + if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY) {
> > + ret = EFI_WRITE_PROTECTED;
> > + goto out;
> > + }
> > +
> > + /* Fill in contents */
> > + memcpy(&var_acc->guid, vendor, sizeof(var_acc->guid));
> > + var_acc->data_size = data_size;
> > + var_acc->name_size = name_size;
> > + var_acc->attr = attributes;
> > + memcpy(var_acc->name, name, name_size);
> > + memcpy((u8 *)var_acc->name + name_size, data, data_size);
> > +
> > +
> > + /* Communicate */
> > + ret = mm_communicate(comm_buf, payload_size);
> > + dev_dbg(pvt_data.dev, "Set Variable %s %d %lx\n", __FILE__, __LINE__, ret);
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static efi_status_t __maybe_unused tee_query_variable_info(u32 attributes,
> > + u64 *max_variable_storage_size,
> > + u64 *remain_variable_storage_size,
> > + u64 *max_variable_size)
> > +{
> > + struct smm_variable_query_info *mm_query_info;
> > + size_t payload_size;
> > + efi_status_t ret;
> > + u8 *comm_buf;
> > +
> > + payload_size = sizeof(*mm_query_info);
> > + comm_buf = setup_mm_hdr((void **)&mm_query_info, payload_size,
> > + SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO,
> > + &ret);
> > + if (!comm_buf)
> > + goto out;
> > +
> > + mm_query_info->attr = attributes;
> > + ret = mm_communicate(comm_buf, payload_size);
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> > + *max_variable_storage_size = mm_query_info->max_variable_storage;
> > + *remain_variable_storage_size =
> > + mm_query_info->remaining_variable_storage;
> > + *max_variable_size = mm_query_info->max_variable_size;
> > +
> > +out:
> > + kfree(comm_buf);
> > + return ret;
> > +}
> > +
> > +static int tee_stmm_efi_probe(struct device *dev)
> > +{
> > + struct tee_ioctl_open_session_arg sess_arg;
> > + efi_status_t ret;
> > + int rc;
> > +
> > + /* Open context with TEE driver */
> > + pvt_data.ctx = tee_client_open_context(NULL, tee_ctx_match, NULL, NULL);
> > + if (IS_ERR(pvt_data.ctx))
> > + return -ENODEV;
> > +
> > + /* Open session with StMM PTA */
> > + memset(&sess_arg, 0, sizeof(sess_arg));
> > + export_uuid(sess_arg.uuid, &tee_stmm_efi_id_table[0].uuid);
> > + rc = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
> > + if ((rc < 0) || (sess_arg.ret != 0)) {
> > + dev_err(dev, "tee_client_open_session failed, err: %x\n",
> > + sess_arg.ret);
> > + rc = -EINVAL;
> > + goto out_ctx;
> > + }
> > + pvt_data.session = sess_arg.session;
> > + pvt_data.dev = dev;
> > +
> > + ret = get_max_payload(&max_payload_size);
> > + if (ret != EFI_SUCCESS) {
> > + rc = -EIO;
> > + goto out_sess;
> > + }
> > +
> > + max_buffer_size = MM_COMMUNICATE_HEADER_SIZE +
> > + MM_VARIABLE_COMMUNICATE_SIZE +
> > + max_payload_size;
> > +
> > + tee_efivar_ops.get_variable = tee_get_variable;
> > + tee_efivar_ops.get_next_variable = tee_get_next_variable;
> > + tee_efivar_ops.set_variable = tee_set_variable;
> > + /* TODO: support non-blocking variant */
> > + tee_efivar_ops.set_variable_nonblocking = NULL;
> > + tee_efivar_ops.query_variable_store = efi_query_variable_store;
> > +
> > + efivars_generic_ops_unregister();
> > + pr_info("Use tee-based EFI runtime variable services\n");
> > + efivars_register(&tee_efivars, &tee_efivar_ops);
> > +
> > + return 0;
> > +
> > +out_sess:
> > + tee_client_close_session(pvt_data.ctx, pvt_data.session);
> > +out_ctx:
> > + tee_client_close_context(pvt_data.ctx);
> > +
> > + return rc;
> > +}
> > +
> > +static int tee_stmm_efi_remove(struct device *dev)
> > +{
> > + efivars_unregister(&tee_efivars);
> > + efivars_generic_ops_register();
> > +
> > + tee_client_close_session(pvt_data.ctx, pvt_data.session);
> > + tee_client_close_context(pvt_data.ctx);
> > +
> > + return 0;
> > +}
> > +
> > +MODULE_DEVICE_TABLE(tee, tee_stmm_efi_id_table);
> > +
> > +static struct tee_client_driver tee_stmm_efi_driver = {
> > + .id_table = tee_stmm_efi_id_table,
> > + .driver = {
> > + .name = "tee-stmm-efi",
> > + .bus = &tee_bus_type,
> > + .probe = tee_stmm_efi_probe,
> > + .remove = tee_stmm_efi_remove,
> > + },
> > +};
> > +
> > +static int __init tee_stmm_efi_mod_init(void)
> > +{
> > + return driver_register(&tee_stmm_efi_driver.driver);
> > +}
> > +
> > +static void __exit tee_stmm_efi_mod_exit(void)
> > +{
> > + driver_unregister(&tee_stmm_efi_driver.driver);
> > +}
> > +
> > +module_init(tee_stmm_efi_mod_init);
> > +module_exit(tee_stmm_efi_mod_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Ilias Apalodimas <ilias.apalodimas at linaro.org>");
> > +MODULE_AUTHOR("Masahisa Kojima <masahisa.kojima at linaro.org>");
> > +MODULE_DESCRIPTION("TEE based EFI runtime variable service driver");
> > --
> > 2.30.2
> >
>
> The TEE API usage looks OK in this patch.
>
> Cheers,
> Jens
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