From 99bfab8b5832273d66d724f906be43fe5bd7c1ba Mon Sep 17 00:00:00 2001
From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Wed, 15 Jul 2020 12:40:35 +0200
Subject: [PATCH] efi_loader: identify PK, KEK, db, dbx correctly
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>
---
include/efi_variable.h | 19 +++++++++++++++++++
lib/efi_loader/efi_var_common.c | 27 +++++++++++++++++++++++++++
lib/efi_loader/efi_variable.c | 27 ++++++++++++++-------------
3 files changed, 60 insertions(+), 13 deletions(-)
diff --git a/include/efi_variable.h b/include/efi_variable.h
index 5eec407a2b..021a74f309 100644
--- a/include/efi_variable.h
+++ b/include/efi_variable.h
@@ -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
diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c
index 36e31b4d45..ee2e67bc8c 100644
--- a/lib/efi_loader/efi_var_common.c
+++ b/lib/efi_loader/efi_var_common.c
@@ -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;
+}
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 64dc3d6df9..ecbc4f7f54 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -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;
--
2.39.5