u-boot/lib/efi_loader/efi_variable.c
Heinrich Schuchardt 7dda16343d efi_loader: pre-seed UEFI variables
Include a file with the initial values for non-volatile UEFI variables
into the U-Boot binary. If this variable is set, changes to variable PK
will not be allowed.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2020-07-16 12:37:02 +02:00

608 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* UEFI runtime variable services
*
* Copyright (c) 2017 Rob Clark
*/
#define LOG_CATEGORY LOGC_EFI
#include <common.h>
#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
static u8 pkcs7_hdr[] = {
/* SEQUENCE */
0x30, 0x82, 0x05, 0xc7,
/* OID: pkcs7-signedData */
0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02,
/* Context Structured? */
0xa0, 0x82, 0x05, 0xb8,
};
/**
* efi_variable_parse_signature - parse a signature in variable
* @buf: Pointer to variable's value
* @buflen: Length of @buf
*
* Parse a signature embedded in variable's value and instantiate
* a pkcs7_message structure. Since pkcs7_parse_message() accepts only
* pkcs7's signedData, some header needed be prepended for correctly
* parsing authentication data, particularly for variable's.
*
* Return: Pointer to pkcs7_message structure on success, NULL on error
*/
static struct pkcs7_message *efi_variable_parse_signature(const void *buf,
size_t buflen)
{
u8 *ebuf;
size_t ebuflen, len;
struct pkcs7_message *msg;
/*
* This is the best assumption to check if the binary is
* already in a form of pkcs7's signedData.
*/
if (buflen > sizeof(pkcs7_hdr) &&
!memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) {
msg = pkcs7_parse_message(buf, buflen);
goto out;
}
/*
* Otherwise, we should add a dummy prefix sequence for pkcs7
* message parser to be able to process.
* NOTE: EDK2 also uses similar hack in WrapPkcs7Data()
* in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c
* TODO:
* The header should be composed in a more refined manner.
*/
EFI_PRINT("Makeshift prefix added to authentication data\n");
ebuflen = sizeof(pkcs7_hdr) + buflen;
if (ebuflen <= 0x7f) {
EFI_PRINT("Data is too short\n");
return NULL;
}
ebuf = malloc(ebuflen);
if (!ebuf) {
EFI_PRINT("Out of memory\n");
return NULL;
}
memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr));
memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen);
len = ebuflen - 4;
ebuf[2] = (len >> 8) & 0xff;
ebuf[3] = len & 0xff;
len = ebuflen - 0x13;
ebuf[0x11] = (len >> 8) & 0xff;
ebuf[0x12] = len & 0xff;
msg = pkcs7_parse_message(ebuf, ebuflen);
free(ebuf);
out:
if (IS_ERR(msg))
return NULL;
return msg;
}
/**
* 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(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;
enum efi_auth_var_type var_type;
efi_status_t ret;
var_sig = NULL;
truststore = NULL;
truststore2 = NULL;
regs = 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(&timestamp, &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 *)&timestamp,
(uint8_t *)&timestamp + 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;
var_sig = efi_variable_parse_signature(auth->auth_info.cert_data,
auth->auth_info.hdr.dwLength
- sizeof(auth->auth_info));
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(L"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(L"KEK");
truststore2 = efi_sigstore_parse_sigdb(L"PK");
if (!truststore) {
if (!truststore2)
goto err;
truststore = truststore2;
truststore2 = NULL;
}
break;
default:
/* TODO: support private authenticated variables */
goto err;
}
/* verify signature */
if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) {
EFI_PRINT("Verified\n");
} else {
if (truststore2 &&
efi_signature_verify_with_sigdb(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(regs);
return ret;
}
#else
static efi_status_t efi_variable_authenticate(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(u16 *variable_name, const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data,
u64 *timep)
{
efi_uintn_t old_size;
struct efi_var_entry *var;
u16 *pdata;
if (!variable_name || !vendor || !data_size)
return EFI_INVALID_PARAMETER;
var = efi_var_mem_find(vendor, variable_name, NULL);
if (!var)
return EFI_NOT_FOUND;
if (attributes)
*attributes = var->attr;
if (timep)
*timep = var->time;
old_size = *data_size;
*data_size = var->length;
if (old_size < var->length)
return EFI_BUFFER_TOO_SMALL;
if (!data)
return EFI_INVALID_PARAMETER;
for (pdata = var->name; *pdata; ++pdata)
;
++pdata;
efi_memcpy_runtime(data, pdata, var->length);
return EFI_SUCCESS;
}
efi_status_t __efi_runtime
efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *vendor)
{
struct efi_var_entry *var;
efi_uintn_t old_size;
u16 *pdata;
if (!variable_name_size || !variable_name || !vendor)
return EFI_INVALID_PARAMETER;
efi_var_mem_find(vendor, variable_name, &var);
if (!var)
return EFI_NOT_FOUND;
for (pdata = var->name; *pdata; ++pdata)
;
++pdata;
old_size = *variable_name_size;
*variable_name_size = (uintptr_t)pdata - (uintptr_t)var->name;
if (old_size < *variable_name_size)
return EFI_BUFFER_TOO_SMALL;
efi_memcpy_runtime(variable_name, var->name, *variable_name_size);
efi_memcpy_runtime(vendor, &var->guid, sizeof(efi_guid_t));
return EFI_SUCCESS;
}
efi_status_t efi_set_variable_int(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;
if (!variable_name || !*variable_name || !vendor ||
((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
!(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)))
return EFI_INVALID_PARAMETER;
/* check if a variable exists */
var = efi_var_mem_find(vendor, variable_name, NULL);
append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
attributes &= ~(u32)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_NONE)
return EFI_WRITE_PROTECTED;
}
/* attributes won't be changed */
if (!delete &&
((ro_check && var->attr != attributes) ||
(!ro_check && ((var->attr & ~(u32)EFI_VARIABLE_READ_ONLY)
!= (attributes & ~(u32)EFI_VARIABLE_READ_ONLY))))) {
return EFI_INVALID_PARAMETER;
}
time = var->time;
} else {
if (delete || append)
/*
* Trying to delete or to update a non-existent
* variable.
*/
return EFI_NOT_FOUND;
}
if (var_type != EFI_AUTH_VAR_NONE) {
/* 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_AUTHENTICATED_WRITE_ACCESS)
return EFI_INVALID_PARAMETER;
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_AUTHENTICATED_WRITE_ACCESS |
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 */
ret = EFI_SUCCESS;
} else if (append) {
u16 *old_data = var->name;
for (; *old_data; ++old_data)
;
++old_data;
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);
}
efi_var_mem_del(var);
if (ret != EFI_SUCCESS)
return ret;
if (var_type == EFI_AUTH_VAR_PK)
ret = efi_init_secure_state();
else
ret = EFI_SUCCESS;
/* Write non-volatile EFI variables to file */
if (attributes & EFI_VARIABLE_NON_VOLATILE &&
ret == EFI_SUCCESS && efi_obj_list_initialized == EFI_SUCCESS)
efi_var_to_file();
return EFI_SUCCESS;
}
efi_status_t efi_query_variable_info_int(u32 attributes,
u64 *maximum_variable_storage_size,
u64 *remaining_variable_storage_size,
u64 *maximum_variable_size)
{
*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
*/
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)
{
return EFI_UNSUPPORTED;
}
/**
* efi_get_variable_runtime() - runtime implementation of GetVariable()
*
* @variable_name: name of the variable
* @vendor: 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 *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data)
{
efi_status_t ret;
ret = efi_get_variable_int(variable_name, vendor, attributes,
data_size, data, NULL);
/* Remove EFI_VARIABLE_READ_ONLY flag */
if (attributes)
*attributes &= EFI_VARIABLE_MASK;
return ret;
}
/**
* 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
* @vendor: 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 *vendor)
{
return efi_get_next_variable_name_int(variable_name_size, variable_name,
vendor);
}
/**
* 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)
{
return EFI_UNSUPPORTED;
}
/**
* 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_init_secure_state();
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);
if (ret != EFI_SUCCESS)
log_err("Invalid EFI variable seed\n");
}
return efi_var_from_file();
}