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efi_loader: Enable run-time variable support for tee based variables

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We recently added functions for storing/restoring variables
from a file to a memory backed buffer marked as __efi_runtime_data
commit f1f990a8c9 ("efi_loader: memory buffer for variables")
commit 5f7dcf079d ("efi_loader: UEFI variable persistence")

Using the same idea we now can support GetVariable() and GetNextVariable()
on the OP-TEE based variables as well.

So let's re-arrange the code a bit and move the commmon code for
accessing variables out of efi_variable.c. Create common functions for
reading variables from memory that both implementations can use on
run-time. Then just use those functions in the run-time variants of the
OP-TEE based EFI variable implementation and initialize the memory
buffer on ExitBootServices()

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Ilias Apalodimas 2020-07-23 15:49:49 +03:00 • committed by Heinrich Schuchardt
parent db94dfbd52
commit e01aed47d6
7 changed files with 222 additions and 154 deletions
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82
lib/efi_loader/efi_variable_tee.c
View file

@ -15,6 +15,8 @@
#include <malloc.h>
#include <mm_communication.h>
#define OPTEE_PAGE_SIZE BIT(12)
extern struct efi_var_file __efi_runtime_data *efi_var_buf;
static efi_uintn_t max_buffer_size; /* comm + var + func + data */
static efi_uintn_t max_payload_size; /* func + data */
@ -237,8 +239,32 @@ efi_status_t EFIAPI get_max_payload(efi_uintn_t *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;
/*
* Although the max payload is configurable on StMM, we only share a
* single page from OP-TEE for the non-secure buffer used to communicate
* with StMM. Since OP-TEE will reject to map anything bigger than that,
* make sure we are in bounds.
*/
if (*size > OPTEE_PAGE_SIZE)
*size = OPTEE_PAGE_SIZE - MM_COMMUNICATE_HEADER_SIZE -
MM_VARIABLE_COMMUNICATE_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:
free(comm_buf);
return ret;
@ -592,39 +618,6 @@ out:
return ret;
}
/**
* efi_get_variable_runtime() - runtime implementation of GetVariable()
*
* @variable_name: name of the variable
* @guid: vendor GUID
* @attributes: attributes of the variable
* @data_size: size of the buffer to which the variable value is copied
* @data: buffer to which the variable value is copied
* Return: status code
*/
static efi_status_t __efi_runtime EFIAPI
efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
u32 *attributes, efi_uintn_t *data_size, void *data)
{
return EFI_UNSUPPORTED;
}
/**
* efi_get_next_variable_name_runtime() - runtime implementation of
* GetNextVariable()
*
* @variable_name_size: size of variable_name buffer in byte
* @variable_name: name of uefi variable's name in u16
* @guid: vendor's guid
* Return: status code
*/
static efi_status_t __efi_runtime EFIAPI
efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *guid)
{
return EFI_UNSUPPORTED;
}
/**
* efi_query_variable_info() - get information about EFI variables
*
@ -674,8 +667,10 @@ efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
*/
void efi_variables_boot_exit_notify(void)
{
u8 *comm_buf;
efi_status_t ret;
u8 *comm_buf;
loff_t len;
struct efi_var_file *var_buf;
comm_buf = setup_mm_hdr(NULL, 0,
SMM_VARIABLE_FUNCTION_EXIT_BOOT_SERVICE, &ret);
@ -688,6 +683,18 @@ void efi_variables_boot_exit_notify(void)
log_err("Unable to notify StMM for ExitBootServices\n");
free(comm_buf);
/*
* Populate the list for runtime variables.
* asking EFI_VARIABLE_RUNTIME_ACCESS is redundant, since
* efi_var_mem_notify_exit_boot_services will clean those, but that's fine
*/
ret = efi_var_collect(&var_buf, &len, EFI_VARIABLE_RUNTIME_ACCESS);
if (ret != EFI_SUCCESS)
log_err("Can't populate EFI variables. No runtime variables will be available\n");
else
memcpy(efi_var_buf, var_buf, len);
free(var_buf);
/* Update runtime service table */
efi_runtime_services.query_variable_info =
efi_query_variable_info_runtime;
@ -707,6 +714,11 @@ efi_status_t efi_init_variables(void)
{
efi_status_t ret;
/* Create a cached copy of the variables that will be enabled on ExitBootServices() */
ret = efi_var_mem_init();
if (ret != EFI_SUCCESS)
return ret;
ret = get_max_payload(&max_payload_size);
if (ret != EFI_SUCCESS)
return ret;