diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index e13a6f9f4c3..cc8371a3bb4 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -62,6 +62,22 @@ config EFI_VARIABLE_FILE_STORE
Select this option if you want non-volatile UEFI variables to be
stored as file /ubootefi.var on the EFI system partition.
+config EFI_RT_VOLATILE_STORE
+ bool "Allow variable runtime services in volatile storage (e.g RAM)"
+ depends on EFI_VARIABLE_FILE_STORE
+ help
+ When EFI variables are stored on file we don't allow SetVariableRT,
+ since the OS doesn't know how to write that file. At he same time
+ we copy runtime variables in DRAM and support GetVariableRT
+
+ Enable this option to allow SetVariableRT on the RAM backend of
+ the EFI variable storage. The OS will be responsible for syncing
+ the RAM contents to the file, otherwise any changes made during
+ runtime won't persist reboots.
+ Authenticated variables are not supported. Note that this will
+ violate the EFI spec since writing auth variables will return
+ EFI_INVALID_PARAMETER
+
config EFI_MM_COMM_TEE
bool "UEFI variables storage service via the trusted world"
depends on OPTEE
diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
index a61c9a77b13..dde083b0966 100644
--- a/lib/efi_loader/efi_runtime.c
+++ b/lib/efi_loader/efi_runtime.c
@@ -127,6 +127,10 @@ efi_status_t efi_init_runtime_supported(void)
EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP |
EFI_RT_SUPPORTED_CONVERT_POINTER;
+ if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE))
+ rt_table->runtime_services_supported |=
+ EFI_RT_SUPPORTED_SET_VARIABLE;
+
/*
* This value must be synced with efi_runtime_detach_list
* as well as efi_runtime_services.
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index e6c1219a11c..47bb7992057 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -219,17 +219,20 @@ efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
return efi_get_next_variable_name_mem(variable_name_size, variable_name, vendor);
}
-efi_status_t efi_set_variable_int(const u16 *variable_name,
- const efi_guid_t *vendor,
- u32 attributes, efi_uintn_t data_size,
- const void *data, bool ro_check)
+/**
+ * setvariable_allowed() - checks defined by the UEFI spec for setvariable
+ *
+ * @variable_name: name of the variable
+ * @vendor: vendor GUID
+ * @attributes: attributes of the variable
+ * @data_size: size of the buffer with the variable value
+ * @data: buffer with the variable value
+ * Return: status code
+ */
+static efi_status_t __efi_runtime
+setvariable_allowed(const u16 *variable_name, const efi_guid_t *vendor,
+ u32 attributes, efi_uintn_t data_size, const void *data)
{
- struct efi_var_entry *var;
- efi_uintn_t ret;
- bool append, delete;
- u64 time = 0;
- enum efi_auth_var_type var_type;
-
if (!variable_name || !*variable_name || !vendor)
return EFI_INVALID_PARAMETER;
@@ -261,6 +264,25 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
!(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)))
return EFI_INVALID_PARAMETER;
+ return EFI_SUCCESS;
+}
+
+efi_status_t efi_set_variable_int(const u16 *variable_name,
+ const efi_guid_t *vendor,
+ u32 attributes, efi_uintn_t data_size,
+ const void *data, bool ro_check)
+{
+ struct efi_var_entry *var;
+ efi_uintn_t ret;
+ bool append, delete;
+ u64 time = 0;
+ enum efi_auth_var_type var_type;
+
+ ret = setvariable_allowed(variable_name, vendor, attributes, data_size,
+ data);
+ if (ret != EFI_SUCCESS)
+ return ret;
+
/* check if a variable exists */
var = efi_var_mem_find(vendor, variable_name, NULL);
append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
@@ -454,7 +476,79 @@ efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
u32 attributes, efi_uintn_t data_size,
const void *data)
{
- return EFI_UNSUPPORTED;
+ struct efi_var_entry *var;
+ efi_uintn_t ret;
+ bool append, delete;
+ u64 time = 0;
+
+ if (!IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE))
+ return EFI_UNSUPPORTED;
+
+ /*
+ * Authenticated variables are not supported. The EFI spec
+ * in ยง32.3.6 requires keys to be stored in non-volatile storage which
+ * is tamper and delete resistant.
+ * The rest of the checks are in setvariable_allowed()
+ */
+ if (attributes & EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
+ return EFI_INVALID_PARAMETER;
+
+ ret = setvariable_allowed(variable_name, vendor, attributes, data_size,
+ data);
+ if (ret != EFI_SUCCESS)
+ return ret;
+
+ /* check if a variable exists */
+ var = efi_var_mem_find(vendor, variable_name, NULL);
+ append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
+ attributes &= ~EFI_VARIABLE_APPEND_WRITE;
+ delete = !append && (!data_size || !attributes);
+
+ /* BS only variables are hidden deny writing them */
+ if (!delete && !(attributes & EFI_VARIABLE_RUNTIME_ACCESS))
+ return EFI_INVALID_PARAMETER;
+
+ if (var) {
+ if (var->attr & EFI_VARIABLE_READ_ONLY ||
+ !(var->attr & EFI_VARIABLE_NON_VOLATILE))
+ return EFI_WRITE_PROTECTED;
+
+ /* attributes won't be changed */
+ if (!delete && (((var->attr & ~EFI_VARIABLE_READ_ONLY) !=
+ (attributes & ~EFI_VARIABLE_READ_ONLY))))
+ return EFI_INVALID_PARAMETER;
+ time = var->time;
+ } else {
+ if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
+ return EFI_INVALID_PARAMETER;
+ if (append && !data_size)
+ return EFI_SUCCESS;
+ if (delete)
+ return EFI_NOT_FOUND;
+ }
+
+ if (delete) {
+ /* EFI_NOT_FOUND has been handled before */
+ attributes = var->attr;
+ ret = EFI_SUCCESS;
+ } else if (append && var) {
+ u16 *old_data = (void *)((uintptr_t)var->name +
+ sizeof(u16) * (u16_strlen(var->name) + 1));
+
+ ret = efi_var_mem_ins(variable_name, vendor, attributes,
+ var->length, old_data, data_size, data,
+ time);
+ } else {
+ ret = efi_var_mem_ins(variable_name, vendor, attributes,
+ data_size, data, 0, NULL, time);
+ }
+
+ if (ret != EFI_SUCCESS)
+ return ret;
+ /* We are always inserting new variables, get rid of the old copy */
+ efi_var_mem_del(var);
+
+ return EFI_SUCCESS;
}
/**
diff --git a/lib/efi_selftest/efi_selftest_variables_runtime.c b/lib/efi_selftest/efi_selftest_variables_runtime.c
index 4700d942410..986924b881d 100644
--- a/lib/efi_selftest/efi_selftest_variables_runtime.c
+++ b/lib/efi_selftest/efi_selftest_variables_runtime.c
@@ -62,9 +62,17 @@ static int execute(void)
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS,
3, v + 4);
- if (ret != EFI_UNSUPPORTED) {
- efi_st_error("SetVariable failed\n");
- return EFI_ST_FAILURE;
+ if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
+ /* At runtime only non-volatile variables may be set. */
+ if (ret != EFI_INVALID_PARAMETER) {
+ efi_st_error("SetVariable failed\n");
+ return EFI_ST_FAILURE;
+ }
+ } else {
+ if (ret != EFI_UNSUPPORTED) {
+ efi_st_error("SetVariable failed\n");
+ return EFI_ST_FAILURE;
+ }
}
len = EFI_ST_MAX_DATA_SIZE;
ret = runtime->get_variable(u"PlatformLangCodes", &guid_vendor0,