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// SPDX-License-Identifier: GPL-2.0+
/*
* UEFI runtime variable services
*
* Copyright (c) 2017 Rob Clark
*/
#define LOG_CATEGORY LOGC_EFI
#include <efi_loader.h>
#include <efi_variable.h>
#include <env.h>
#include <env_internal.h>
#include <hexdump.h>
#include <log.h>
#include <malloc.h>
#include <rtc.h>
#include <search.h>
#include <uuid.h>
#include <crypto/pkcs7_parser.h>
#include <linux/compat.h>
#include <u-boot/crc.h>
#include <asm/sections.h>
#ifdef CONFIG_EFI_SECURE_BOOT
/**
* efi_variable_authenticate - authenticate a variable
* @variable: Variable name in u16
* @vendor: Guid of variable
* @data_size: Size of @data
* @data: Pointer to variable's value
* @given_attr: Attributes to be given at SetVariable()
* @env_attr: Attributes that an existing variable holds
* @time: signed time that an existing variable holds
*
* Called by efi_set_variable() to verify that the input is correct.
* Will replace the given data pointer with another that points to
* the actual data to store in the internal memory.
* On success, @data and @data_size will be replaced with variable's
* actual data, excluding authentication data, and its size, and variable's
* attributes and signed time will also be returned in @env_attr and @time,
* respectively.
*
* Return: status code
*/
static efi_status_t efi_variable_authenticate(const u16 *variable,
const efi_guid_t *vendor,
efi_uintn_t *data_size,
const void **data, u32 given_attr,
u32 *env_attr, u64 *time)
{
const struct efi_variable_authentication_2 *auth;
struct efi_signature_store *truststore, *truststore2;
struct pkcs7_message *var_sig;
struct efi_image_regions *regs;
struct efi_time timestamp;
struct rtc_time tm;
u64 new_time;
u8 *ebuf;
enum efi_auth_var_type var_type;
efi_status_t ret;
var_sig = NULL;
truststore = NULL;
truststore2 = NULL;
regs = NULL;
ebuf = NULL;
ret = EFI_SECURITY_VIOLATION;
if (*data_size < sizeof(struct efi_variable_authentication_2))
goto err;
/* authentication data */
auth = *data;
if (*data_size < (sizeof(auth->time_stamp)
+ auth->auth_info.hdr.dwLength))
goto err;
if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
goto err;
memcpy(×tamp, &auth->time_stamp, sizeof(timestamp));
if (timestamp.pad1 || timestamp.nanosecond || timestamp.timezone ||
timestamp.daylight || timestamp.pad2)
goto err;
*data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
*data_size -= (sizeof(auth->time_stamp)
+ auth->auth_info.hdr.dwLength);
memset(&tm, 0, sizeof(tm));
tm.tm_year = timestamp.year;
tm.tm_mon = timestamp.month;
tm.tm_mday = timestamp.day;
tm.tm_hour = timestamp.hour;
tm.tm_min = timestamp.minute;
tm.tm_sec = timestamp.second;
new_time = rtc_mktime(&tm);
if (!efi_secure_boot_enabled()) {
/* finished checking */
*time = new_time;
return EFI_SUCCESS;
}
if (new_time <= *time)
goto err;
/* data to be digested */
regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
if (!regs)
goto err;
regs->max = 5;
efi_image_region_add(regs, (uint8_t *)variable,
(uint8_t *)variable
+ u16_strlen(variable) * sizeof(u16), 1);
efi_image_region_add(regs, (uint8_t *)vendor,
(uint8_t *)vendor + sizeof(*vendor), 1);
efi_image_region_add(regs, (uint8_t *)&given_attr,
(uint8_t *)&given_attr + sizeof(given_attr), 1);
efi_image_region_add(regs, (uint8_t *)×tamp,
(uint8_t *)×tamp + sizeof(timestamp), 1);
efi_image_region_add(regs, (uint8_t *)*data,
(uint8_t *)*data + *data_size, 1);
/* variable's signature list */
if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
goto err;
/* ebuf should be kept valid during the authentication */
var_sig = efi_parse_pkcs7_header(auth->auth_info.cert_data,
auth->auth_info.hdr.dwLength
- sizeof(auth->auth_info),
&ebuf);
if (!var_sig) {
EFI_PRINT("Parsing variable's signature failed\n");
goto err;
}
/* signature database used for authentication */
var_type = efi_auth_var_get_type(variable, vendor);
switch (var_type) {
case EFI_AUTH_VAR_PK:
case EFI_AUTH_VAR_KEK:
/* with PK */
truststore = efi_sigstore_parse_sigdb(u"PK");
if (!truststore)
goto err;
break;
case EFI_AUTH_VAR_DB:
case EFI_AUTH_VAR_DBX:
/* with PK and KEK */
truststore = efi_sigstore_parse_sigdb(u"KEK");
truststore2 = efi_sigstore_parse_sigdb(u"PK");
if (!truststore) {
if (!truststore2)
goto err;
truststore = truststore2;
truststore2 = NULL;
}
break;
default:
/* TODO: support private authenticated variables */
ret = EFI_UNSUPPORTED;
goto err;
}
/* verify signature */
if (efi_signature_verify(regs, var_sig, truststore, NULL)) {
EFI_PRINT("Verified\n");
} else {
if (truststore2 &&
efi_signature_verify(regs, var_sig, truststore2, NULL)) {
EFI_PRINT("Verified\n");
} else {
EFI_PRINT("Verifying variable's signature failed\n");
goto err;
}
}
/* finished checking */
*time = new_time;
ret = EFI_SUCCESS;
err:
efi_sigstore_free(truststore);
efi_sigstore_free(truststore2);
pkcs7_free_message(var_sig);
free(ebuf);
free(regs);
return ret;
}
#else
static efi_status_t efi_variable_authenticate(const u16 *variable,
const efi_guid_t *vendor,
efi_uintn_t *data_size,
const void **data, u32 given_attr,
u32 *env_attr, u64 *time)
{
return EFI_SUCCESS;
}
#endif /* CONFIG_EFI_SECURE_BOOT */
efi_status_t __efi_runtime
efi_get_variable_int(const u16 *variable_name, const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data,
u64 *timep)
{
return efi_get_variable_mem(variable_name, vendor, attributes, data_size,
data, timep, 0);
}
efi_status_t __efi_runtime
efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *vendor)
{
return efi_get_next_variable_name_mem(variable_name_size, variable_name,
vendor, 0);
}
/**
* 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)
{
if (!variable_name || !*variable_name || !vendor)
return EFI_INVALID_PARAMETER;
if (data_size && !data)
return EFI_INVALID_PARAMETER;
/*
* EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated.
* We don't support EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS.
*/
if (attributes & (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS | \
EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS))
return EFI_UNSUPPORTED;
/* Make sure if runtime bit is set, boot service bit is set also */
if ((attributes &
(EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)) ==
EFI_VARIABLE_RUNTIME_ACCESS)
return EFI_INVALID_PARAMETER;
/* only EFI_VARIABLE_NON_VOLATILE attribute is invalid */
if ((attributes & EFI_VARIABLE_MASK) == EFI_VARIABLE_NON_VOLATILE)
return EFI_INVALID_PARAMETER;
/* Make sure HR is set with NV, BS and RT */
if (attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD &&
(!(attributes & EFI_VARIABLE_NON_VOLATILE) ||
!(attributes & EFI_VARIABLE_RUNTIME_ACCESS) ||
!(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);
delete = !append && (!data_size || !attributes);
/* check attributes */
var_type = efi_auth_var_get_type(variable_name, vendor);
if (var) {
if (ro_check && (var->attr & EFI_VARIABLE_READ_ONLY))
return EFI_WRITE_PROTECTED;
if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
if (var_type >= EFI_AUTH_VAR_PK)
return EFI_WRITE_PROTECTED;
}
/* attributes won't be changed */
if (!delete &&
((ro_check && var->attr != (attributes & ~EFI_VARIABLE_APPEND_WRITE)) ||
(!ro_check && ((var->attr & ~EFI_VARIABLE_READ_ONLY)
!= (attributes & ~EFI_VARIABLE_READ_ONLY))))) {
return EFI_INVALID_PARAMETER;
}
time = var->time;
} else {
/*
* UEFI specification does not clearly describe the expected
* behavior of append write with data size 0, we follow
* the EDK II reference implementation.
*/
if (append && !data_size)
return EFI_SUCCESS;
/*
* EFI_VARIABLE_APPEND_WRITE to non-existent variable is accepted
* and new variable is created in EDK II reference implementation.
* We follow it and only check the deletion here.
*/
if (delete)
/* Trying to delete a non-existent variable. */
return EFI_NOT_FOUND;
}
if (var_type >= EFI_AUTH_VAR_PK) {
/* authentication is mandatory */
if (!(attributes &
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
EFI_PRINT("%ls: TIME_BASED_AUTHENTICATED_WRITE_ACCESS required\n",
variable_name);
return EFI_INVALID_PARAMETER;
}
}
/* authenticate a variable */
if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
if (attributes &
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
u32 env_attr;
ret = efi_variable_authenticate(variable_name, vendor,
&data_size, &data,
attributes, &env_attr,
&time);
if (ret != EFI_SUCCESS)
return ret;
/* last chance to check for delete */
if (!data_size)
delete = true;
}
} else {
if (attributes &
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
EFI_PRINT("Secure boot is not configured\n");
return EFI_INVALID_PARAMETER;
}
}
if (delete) {
/* EFI_NOT_FOUND has been handled before */
attributes = var->attr;
ret = EFI_SUCCESS;
} else if (append && var) {
/*
* data is appended if EFI_VARIABLE_APPEND_WRITE is set and
* variable exists.
*/
u16 *old_data = var->name;
for (; *old_data; ++old_data)
;
++old_data;
ret = efi_var_mem_ins(variable_name, vendor,
attributes & ~EFI_VARIABLE_APPEND_WRITE,
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;
efi_var_mem_del(var);
if (var_type == EFI_AUTH_VAR_PK)
ret = efi_init_secure_state();
else
ret = EFI_SUCCESS;
/*
* Write non-volatile EFI variables to file
* TODO: check if a value change has occured to avoid superfluous writes
*/
if (attributes & EFI_VARIABLE_NON_VOLATILE)
efi_var_to_file();
return EFI_SUCCESS;
}
efi_status_t __efi_runtime
efi_query_variable_info_int(u32 attributes,
u64 *maximum_variable_storage_size,
u64 *remaining_variable_storage_size,
u64 *maximum_variable_size)
{
if (!maximum_variable_storage_size ||
!remaining_variable_storage_size ||
!maximum_variable_size || !attributes)
return EFI_INVALID_PARAMETER;
/* EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated */
if ((attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS) ||
((attributes & EFI_VARIABLE_MASK) == 0))
return EFI_UNSUPPORTED;
if ((attributes & EFI_VARIABLE_MASK) == EFI_VARIABLE_NON_VOLATILE)
return EFI_INVALID_PARAMETER;
/* Make sure if runtime bit is set, boot service bit is set also. */
if ((attributes &
(EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)) ==
EFI_VARIABLE_RUNTIME_ACCESS)
return EFI_INVALID_PARAMETER;
if (attributes & ~EFI_VARIABLE_MASK)
return EFI_INVALID_PARAMETER;
*maximum_variable_storage_size = EFI_VAR_BUF_SIZE -
sizeof(struct efi_var_file);
*remaining_variable_storage_size = efi_var_mem_free();
*maximum_variable_size = EFI_VAR_BUF_SIZE -
sizeof(struct efi_var_file) -
sizeof(struct efi_var_entry);
return EFI_SUCCESS;
}
/**
* efi_query_variable_info_runtime() - runtime implementation of
* QueryVariableInfo()
*
* @attributes: bitmask to select variables to be
* queried
* @maximum_variable_storage_size: maximum size of storage area for the
* selected variable types
* @remaining_variable_storage_size: remaining size of storage are for the
* selected variable types
* @maximum_variable_size: maximum size of a variable of the
* selected type
* Returns: status code
*/
static efi_status_t __efi_runtime EFIAPI efi_query_variable_info_runtime(
u32 attributes,
u64 *maximum_variable_storage_size,
u64 *remaining_variable_storage_size,
u64 *maximum_variable_size)
{
if (!(attributes & EFI_VARIABLE_RUNTIME_ACCESS))
return EFI_INVALID_PARAMETER;
if ((attributes & (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS |
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS |
EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS)))
return EFI_UNSUPPORTED;
return efi_query_variable_info_int(attributes,
maximum_variable_storage_size,
remaining_variable_storage_size,
maximum_variable_size);
}
/**
* efi_set_variable_runtime() - runtime implementation of 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 EFIAPI
efi_set_variable_runtime(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;
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;
}
/**
* efi_variables_boot_exit_notify() - notify ExitBootServices() is called
*/
void efi_variables_boot_exit_notify(void)
{
/* Switch variable services functions to runtime version */
efi_runtime_services.get_variable = efi_get_variable_runtime;
efi_runtime_services.get_next_variable_name =
efi_get_next_variable_name_runtime;
efi_runtime_services.set_variable = efi_set_variable_runtime;
efi_runtime_services.query_variable_info =
efi_query_variable_info_runtime;
efi_update_table_header_crc32(&efi_runtime_services.hdr);
}
/**
* efi_init_variables() - initialize variable services
*
* Return: status code
*/
efi_status_t efi_init_variables(void)
{
efi_status_t ret;
ret = efi_var_mem_init();
if (ret != EFI_SUCCESS)
return ret;
ret = efi_var_from_file();
if (ret != EFI_SUCCESS)
return ret;
if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
ret = efi_var_restore((struct efi_var_file *)
__efi_var_file_begin, true);
if (ret != EFI_SUCCESS)
log_err("Invalid EFI variable seed\n");
}
return efi_init_secure_state();
}
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