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// SPDX-License-Identifier: GPL-2.0+
/*
* EFI utils
*
* Copyright (c) 2017 Rob Clark
*/
#include <malloc.h>
#include <charset.h>
#include <efi_loader.h>
#define READ_ONLY BIT(31)
/*
* Mapping between EFI variables and u-boot variables:
*
* efi_$guid_$varname = {attributes}(type)value
*
* For example:
*
* efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
* "{ro,boot,run}(blob)0000000000000000"
* efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
* "(blob)00010000"
*
* The attributes are a comma separated list of these possible
* attributes:
*
* + ro - read-only
* + boot - boot-services access
* + run - runtime access
*
* NOTE: with current implementation, no variables are available after
* ExitBootServices, and all are persisted (if possible).
*
* If not specified, the attributes default to "{boot}".
*
* The required type is one of:
*
* + utf8 - raw utf8 string
* + blob - arbitrary length hex string
*
* Maybe a utf16 type would be useful to for a string value to be auto
* converted to utf16?
*/
#define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))
static int hex(int ch)
{
if (ch >= 'a' && ch <= 'f')
return ch-'a'+10;
if (ch >= '0' && ch <= '9')
return ch-'0';
if (ch >= 'A' && ch <= 'F')
return ch-'A'+10;
return -1;
}
static int hex2mem(u8 *mem, const char *hexstr, int size)
{
int nibble;
int i;
for (i = 0; i < size; i++) {
if (*hexstr == '\0')
break;
nibble = hex(*hexstr);
if (nibble < 0)
return -1;
*mem = nibble;
hexstr++;
nibble = hex(*hexstr);
if (nibble < 0)
return -1;
*mem = (*mem << 4) | nibble;
hexstr++;
mem++;
}
return i;
}
static char *mem2hex(char *hexstr, const u8 *mem, int count)
{
static const char hexchars[] = "0123456789abcdef";
while (count-- > 0) {
u8 ch = *mem++;
*hexstr++ = hexchars[ch >> 4];
*hexstr++ = hexchars[ch & 0xf];
}
return hexstr;
}
static efi_status_t efi_to_native(char **native, const u16 *variable_name,
efi_guid_t *vendor)
{
size_t len;
char *pos;
len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
*native = malloc(len);
if (!*native)
return EFI_OUT_OF_RESOURCES;
pos = *native;
pos += sprintf(pos, "efi_%pUl_", vendor);
utf16_utf8_strcpy(&pos, variable_name);
return EFI_SUCCESS;
}
static const char *prefix(const char *str, const char *prefix)
{
size_t n = strlen(prefix);
if (!strncmp(prefix, str, n))
return str + n;
return NULL;
}
/* parse attributes part of variable value, if present: */
static const char *parse_attr(const char *str, u32 *attrp)
{
u32 attr = 0;
char sep = '{';
if (*str != '{') {
*attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
return str;
}
while (*str == sep) {
const char *s;
str++;
if ((s = prefix(str, "ro"))) {
attr |= READ_ONLY;
} else if ((s = prefix(str, "boot"))) {
attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
} else if ((s = prefix(str, "run"))) {
attr |= EFI_VARIABLE_RUNTIME_ACCESS;
} else {
printf("invalid attribute: %s\n", str);
break;
}
str = s;
sep = ',';
}
str++;
*attrp = attr;
return str;
}
/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetVariable.28.29 */
efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size,
void *data)
{
char *native_name;
efi_status_t ret;
unsigned long in_size;
const char *val, *s;
u32 attr;
EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
data_size, data);
if (!variable_name || !vendor || !data_size)
return EFI_EXIT(EFI_INVALID_PARAMETER);
ret = efi_to_native(&native_name, variable_name, vendor);
if (ret)
return EFI_EXIT(ret);
debug("%s: get '%s'\n", __func__, native_name);
val = env_get(native_name);
free(native_name);
if (!val)
return EFI_EXIT(EFI_NOT_FOUND);
val = parse_attr(val, &attr);
in_size = *data_size;
if ((s = prefix(val, "(blob)"))) {
unsigned len = strlen(s);
/* number of hexadecimal digits must be even */
if (len & 1)
return EFI_EXIT(EFI_DEVICE_ERROR);
/* two characters per byte: */
len /= 2;
*data_size = len;
if (in_size < len)
return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
if (!data)
return EFI_EXIT(EFI_INVALID_PARAMETER);
if (hex2mem(data, s, len) != len)
return EFI_EXIT(EFI_DEVICE_ERROR);
debug("%s: got value: \"%s\"\n", __func__, s);
} else if ((s = prefix(val, "(utf8)"))) {
unsigned len = strlen(s) + 1;
*data_size = len;
if (in_size < len)
return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
if (!data)
return EFI_EXIT(EFI_INVALID_PARAMETER);
memcpy(data, s, len);
((char *)data)[len] = '\0';
debug("%s: got value: \"%s\"\n", __func__, (char *)data);
} else {
debug("%s: invalid value: '%s'\n", __func__, val);
return EFI_EXIT(EFI_DEVICE_ERROR);
}
if (attributes)
*attributes = attr & EFI_VARIABLE_MASK;
return EFI_EXIT(EFI_SUCCESS);
}
/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetNextVariableName.28.29 */
efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
u16 *variable_name,
efi_guid_t *vendor)
{
EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
return EFI_EXIT(EFI_DEVICE_ERROR);
}
/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#SetVariable.28.29 */
efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
u32 attributes, efi_uintn_t data_size,
void *data)
{
char *native_name = NULL, *val = NULL, *s;
efi_status_t ret = EFI_SUCCESS;
u32 attr;
EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
data_size, data);
if (!variable_name || !vendor) {
ret = EFI_INVALID_PARAMETER;
goto out;
}
ret = efi_to_native(&native_name, variable_name, vendor);
if (ret)
goto out;
#define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)
if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
/* delete the variable: */
env_set(native_name, NULL);
ret = EFI_SUCCESS;
goto out;
}
val = env_get(native_name);
if (val) {
parse_attr(val, &attr);
if (attr & READ_ONLY) {
/* We should not free val */
val = NULL;
ret = EFI_WRITE_PROTECTED;
goto out;
}
}
val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1);
if (!val) {
ret = EFI_OUT_OF_RESOURCES;
goto out;
}
s = val;
/* store attributes: */
attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS);
s += sprintf(s, "{");
while (attributes) {
u32 attr = 1 << (ffs(attributes) - 1);
if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
s += sprintf(s, "boot");
else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
s += sprintf(s, "run");
attributes &= ~attr;
if (attributes)
s += sprintf(s, ",");
}
s += sprintf(s, "}");
/* store payload: */
s += sprintf(s, "(blob)");
s = mem2hex(s, data, data_size);
*s = '\0';
debug("%s: setting: %s=%s\n", __func__, native_name, val);
if (env_set(native_name, val))
ret = EFI_DEVICE_ERROR;
out:
free(native_name);
free(val);
return EFI_EXIT(ret);
}
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