u-boot/lib/efi_loader/efi_variable.c
AKASHI Takahiro a2c6983740 efi_loader: variable: attributes may not be changed if a variable exists
If a variable already exists, efi_set_variable() should not change
the variable's attributes. This patch enforces it.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2019-05-24 18:58:14 +02:00

515 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* EFI utils
*
* Copyright (c) 2017 Rob Clark
*/
#include <malloc.h>
#include <charset.h>
#include <efi_loader.h>
#include <hexdump.h>
#include <environment.h>
#include <search.h>
#include <uuid.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_"))
/**
* efi_to_native() - convert the UEFI variable name and vendor GUID to U-Boot
* variable name
*
* The U-Boot variable name is a concatenation of prefix 'efi', the hexstring
* encoded vendor GUID, and the UTF-8 encoded UEFI variable name separated by
* underscores, e.g. 'efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder'.
*
* @native: pointer to pointer to U-Boot variable name
* @variable_name: UEFI variable name
* @vendor: vendor GUID
* Return: status code
*/
static efi_status_t efi_to_native(char **native, const u16 *variable_name,
const 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;
}
/**
* prefix() - skip over prefix
*
* Skip over a prefix string.
*
* @str: string with prefix
* @prefix: prefix string
* Return: string without prefix, or NULL if prefix not found
*/
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_attr() - decode attributes part of variable value
*
* Convert the string encoded attributes of a UEFI variable to a bit mask.
* TODO: Several attributes are not supported.
*
* @str: value of U-Boot variable
* @attrp: pointer to UEFI attributes
* Return: pointer to remainder of U-Boot variable value
*/
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;
}
/**
* efi_efi_get_variable() - retrieve value of a UEFI variable
*
* This function implements the GetVariable runtime service.
*
* See the Unified Extensible Firmware Interface (UEFI) specification for
* details.
*
* @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
*/
efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
const 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);
EFI_PRINT("get '%s'\n", 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)"))) {
size_t 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) {
ret = EFI_BUFFER_TOO_SMALL;
goto out;
}
if (!data)
return EFI_EXIT(EFI_INVALID_PARAMETER);
if (hex2bin(data, s, len))
return EFI_EXIT(EFI_DEVICE_ERROR);
EFI_PRINT("got value: \"%s\"\n", s);
} else if ((s = prefix(val, "(utf8)"))) {
unsigned len = strlen(s) + 1;
*data_size = len;
if (in_size < len) {
ret = EFI_BUFFER_TOO_SMALL;
goto out;
}
if (!data)
return EFI_EXIT(EFI_INVALID_PARAMETER);
memcpy(data, s, len);
((char *)data)[len] = '\0';
EFI_PRINT("got value: \"%s\"\n", (char *)data);
} else {
EFI_PRINT("invalid value: '%s'\n", val);
return EFI_EXIT(EFI_DEVICE_ERROR);
}
out:
if (attributes)
*attributes = attr & EFI_VARIABLE_MASK;
return EFI_EXIT(ret);
}
static char *efi_variables_list;
static char *efi_cur_variable;
/**
* parse_uboot_variable() - parse a u-boot variable and get uefi-related
* information
* @variable: whole data of u-boot variable (ie. name=value)
* @variable_name_size: size of variable_name buffer in byte
* @variable_name: name of uefi variable in u16, null-terminated
* @vendor: vendor's guid
* @attributes: attributes
*
* A uefi variable is encoded into a u-boot variable as described above.
* This function parses such a u-boot variable and retrieve uefi-related
* information into respective parameters. In return, variable_name_size
* is the size of variable name including NULL.
*
* Return: EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
the entire variable list has been returned,
otherwise non-zero status code
*/
static efi_status_t parse_uboot_variable(char *variable,
efi_uintn_t *variable_name_size,
u16 *variable_name,
const efi_guid_t *vendor,
u32 *attributes)
{
char *guid, *name, *end, c;
unsigned long name_len;
u16 *p;
guid = strchr(variable, '_');
if (!guid)
return EFI_INVALID_PARAMETER;
guid++;
name = strchr(guid, '_');
if (!name)
return EFI_INVALID_PARAMETER;
name++;
end = strchr(name, '=');
if (!end)
return EFI_INVALID_PARAMETER;
name_len = end - name;
if (*variable_name_size < (name_len + 1)) {
*variable_name_size = name_len + 1;
return EFI_BUFFER_TOO_SMALL;
}
end++; /* point to value */
/* variable name */
p = variable_name;
utf8_utf16_strncpy(&p, name, name_len);
variable_name[name_len] = 0;
*variable_name_size = name_len + 1;
/* guid */
c = *(name - 1);
*(name - 1) = '\0'; /* guid need be null-terminated here */
uuid_str_to_bin(guid, (unsigned char *)vendor, UUID_STR_FORMAT_GUID);
*(name - 1) = c;
/* attributes */
parse_attr(end, attributes);
return EFI_SUCCESS;
}
/**
* efi_get_next_variable_name() - enumerate the current variable names
* @variable_name_size: size of variable_name buffer in byte
* @variable_name: name of uefi variable's name in u16
* @vendor: vendor's guid
*
* This function implements the GetNextVariableName service.
*
* See the Unified Extensible Firmware Interface (UEFI) specification for
* details: http://wiki.phoenix.com/wiki/index.php/
* EFI_RUNTIME_SERVICES#GetNextVariableName.28.29
*
* Return: status code
*/
efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
u16 *variable_name,
const efi_guid_t *vendor)
{
char *native_name, *variable;
ssize_t name_len, list_len;
char regex[256];
char * const regexlist[] = {regex};
u32 attributes;
int i;
efi_status_t ret;
EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
if (!variable_name_size || !variable_name || !vendor)
return EFI_EXIT(EFI_INVALID_PARAMETER);
if (variable_name[0]) {
/* check null-terminated string */
for (i = 0; i < *variable_name_size; i++)
if (!variable_name[i])
break;
if (i >= *variable_name_size)
return EFI_EXIT(EFI_INVALID_PARAMETER);
/* search for the last-returned variable */
ret = efi_to_native(&native_name, variable_name, vendor);
if (ret)
return EFI_EXIT(ret);
name_len = strlen(native_name);
for (variable = efi_variables_list; variable && *variable;) {
if (!strncmp(variable, native_name, name_len) &&
variable[name_len] == '=')
break;
variable = strchr(variable, '\n');
if (variable)
variable++;
}
free(native_name);
if (!(variable && *variable))
return EFI_EXIT(EFI_INVALID_PARAMETER);
/* next variable */
variable = strchr(variable, '\n');
if (variable)
variable++;
if (!(variable && *variable))
return EFI_EXIT(EFI_NOT_FOUND);
} else {
/*
*new search: free a list used in the previous search
*/
free(efi_variables_list);
efi_variables_list = NULL;
efi_cur_variable = NULL;
snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
list_len = hexport_r(&env_htab, '\n',
H_MATCH_REGEX | H_MATCH_KEY,
&efi_variables_list, 0, 1, regexlist);
/* 1 indicates that no match was found */
if (list_len <= 1)
return EFI_EXIT(EFI_NOT_FOUND);
variable = efi_variables_list;
}
ret = parse_uboot_variable(variable, variable_name_size, variable_name,
vendor, &attributes);
return EFI_EXIT(ret);
}
/**
* efi_efi_set_variable() - set value of a UEFI variable
*
* This function implements the SetVariable runtime service.
*
* See the Unified Extensible Firmware Interface (UEFI) specification for
* details.
*
* @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
*/
efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
const efi_guid_t *vendor, u32 attributes,
efi_uintn_t data_size, const 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);
/* TODO: implement APPEND_WRITE */
if (!variable_name || !vendor ||
(attributes & EFI_VARIABLE_APPEND_WRITE)) {
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);
/* We should not free val */
val = NULL;
if (attr & READ_ONLY) {
ret = EFI_WRITE_PROTECTED;
goto out;
}
/*
* attributes won't be changed
* TODO: take care of APPEND_WRITE once supported
*/
if (attr != attributes) {
ret = EFI_INVALID_PARAMETER;
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
* TODO: several attributes are not supported
*/
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 = bin2hex(s, data, data_size);
*s = '\0';
EFI_PRINT("setting: %s=%s\n", native_name, val);
if (env_set(native_name, val))
ret = EFI_DEVICE_ERROR;
out:
free(native_name);
free(val);
return EFI_EXIT(ret);
}