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efi_loader: identify PK, KEK, db, dbx correctly

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To determine if a varible is on the of the authentication variables
PK, KEK, db, dbx we have to check both the name and the GUID.

Provide a function converting the variable-name/guid pair to an enum and
use it consistently.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2020-07-15 12:40:35 +02:00
parent be66b89da3
commit 99bfab8b58
3 changed files with 60 additions and 13 deletions
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19
include/efi_variable.h
View file

@ -10,6 +10,16 @@
#define EFI_VARIABLE_READ_ONLY BIT(31)
enum efi_auth_var_type {
EFI_AUTH_VAR_NONE = 0,
EFI_AUTH_VAR_PK,
EFI_AUTH_VAR_KEK,
EFI_AUTH_VAR_DB,
EFI_AUTH_VAR_DBX,
EFI_AUTH_VAR_DBT,
EFI_AUTH_VAR_DBR,
};
/**
* efi_get_variable() - retrieve value of a UEFI variable
*
@ -202,4 +212,13 @@ u64 efi_var_mem_free(void);
*/
efi_status_t efi_init_secure_state(void);
/**
* efi_auth_var_get_type() - convert variable name and guid to enum
*
* @name: name of UEFI variable
* @guid: guid of UEFI variable
* Return: identifier for authentication related variables
*/
enum efi_auth_var_type efi_auth_var_get_type(u16 *name, const efi_guid_t *guid);
#endif

27
lib/efi_loader/efi_var_common.c
View file

@ -16,6 +16,23 @@ enum efi_secure_mode {
EFI_MODE_DEPLOYED,
};
struct efi_auth_var_name_type {
const u16 *name;
const efi_guid_t *guid;
const enum efi_auth_var_type type;
};
static const struct efi_auth_var_name_type name_type[] = {
{u"PK", &efi_global_variable_guid, EFI_AUTH_VAR_PK},
{u"KEK", &efi_global_variable_guid, EFI_AUTH_VAR_KEK},
{u"db", &efi_guid_image_security_database, EFI_AUTH_VAR_DB},
{u"dbx", &efi_guid_image_security_database, EFI_AUTH_VAR_DBX},
/* not used yet
{u"dbt", &efi_guid_image_security_database, EFI_AUTH_VAR_DBT},
{u"dbr", &efi_guid_image_security_database, EFI_AUTH_VAR_DBR},
*/
};
static bool efi_secure_boot;
static enum efi_secure_mode efi_secure_mode;
@ -293,3 +310,13 @@ bool efi_secure_boot_enabled(void)
{
return efi_secure_boot;
}
enum efi_auth_var_type efi_auth_var_get_type(u16 *name, const efi_guid_t *guid)
{
for (size_t i = 0; i < ARRAY_SIZE(name_type); ++i) {
if (!u16_strcmp(name, name_type[i].name) &&
!guidcmp(guid, name_type[i].guid))
return name_type[i].type;
}
return EFI_AUTH_VAR_NONE;
}

27
lib/efi_loader/efi_variable.c
View file

@ -133,6 +133,7 @@ static efi_status_t efi_variable_authenticate(u16 *variable,
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;
@ -209,18 +210,20 @@ static efi_status_t efi_variable_authenticate(u16 *variable,
}
/* signature database used for authentication */
if (u16_strcmp(variable, L"PK") == 0 ||
u16_strcmp(variable, L"KEK") == 0) {
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;
} else if (u16_strcmp(variable, L"db") == 0 ||
u16_strcmp(variable, L"dbx") == 0) {
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;
@ -228,7 +231,8 @@ static efi_status_t efi_variable_authenticate(u16 *variable,
truststore = truststore2;
truststore2 = NULL;
}
} else {
break;
default:
/* TODO: support private authenticated variables */
goto err;
}
@ -347,6 +351,7 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
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) &&
@ -381,12 +386,8 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
return EFI_NOT_FOUND;
}
if (((!u16_strcmp(variable_name, L"PK") ||
!u16_strcmp(variable_name, L"KEK")) &&
!guidcmp(vendor, &efi_global_variable_guid)) ||
((!u16_strcmp(variable_name, L"db") ||
!u16_strcmp(variable_name, L"dbx")) &&
!guidcmp(vendor, &efi_guid_image_security_database))) {
var_type = efi_auth_var_get_type(variable_name, vendor);
if (var_type != EFI_AUTH_VAR_NONE) {
/* authentication is mandatory */
if (!(attributes &
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
@ -445,7 +446,7 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
if (ret != EFI_SUCCESS)
return ret;
if (!u16_strcmp(variable_name, L"PK"))
if (var_type == EFI_AUTH_VAR_PK)
ret = efi_init_secure_state();
else
ret = EFI_SUCCESS;