The UEFI specification requires that the signature database may only be stored in tamper-resistant storage. So these variable may not be read from an unsigned file.
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com --- include/efi_variable.h | 5 +++- lib/efi_loader/efi_var_common.c | 2 -- lib/efi_loader/efi_var_file.c | 41 ++++++++++++++++++++------------- lib/efi_loader/efi_variable.c | 2 +- 4 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/include/efi_variable.h b/include/efi_variable.h index 4623a64142..2d97655e1f 100644 --- a/include/efi_variable.h +++ b/include/efi_variable.h @@ -161,10 +161,13 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t * /** * efi_var_restore() - restore EFI variables from buffer * + * Only if @safe is set secure boot related variables will be restored. + * * @buf: buffer + * @safe: restoring from tamper-resistant storage * Return: status code */ -efi_status_t efi_var_restore(struct efi_var_file *buf); +efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe);
/** * efi_var_from_file() - read variables from file diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c index 3d92afe2eb..005c03ea5f 100644 --- a/lib/efi_loader/efi_var_common.c +++ b/lib/efi_loader/efi_var_common.c @@ -32,10 +32,8 @@ static const struct efi_auth_var_name_type name_type[] = { {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; diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c index de076b8cbc..c7c6805ed0 100644 --- a/lib/efi_loader/efi_var_file.c +++ b/lib/efi_loader/efi_var_file.c @@ -148,9 +148,10 @@ error: #endif }
-efi_status_t efi_var_restore(struct efi_var_file *buf) +efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe) { struct efi_var_entry *var, *last_var; + u16 *data; efi_status_t ret;
if (buf->reserved || buf->magic != EFI_VAR_FILE_MAGIC || @@ -160,21 +161,29 @@ efi_status_t efi_var_restore(struct efi_var_file *buf) return EFI_INVALID_PARAMETER; }
- var = buf->var; last_var = (struct efi_var_entry *)((u8 *)buf + buf->length); - while (var < last_var) { - u16 *data = var->name + u16_strlen(var->name) + 1; - - if (var->attr & EFI_VARIABLE_NON_VOLATILE && var->length) { - ret = efi_var_mem_ins(var->name, &var->guid, var->attr, - var->length, data, 0, NULL, - var->time); - if (ret != EFI_SUCCESS) - log_err("Failed to set EFI variable %ls\n", - var->name); - } - var = (struct efi_var_entry *) - ALIGN((uintptr_t)data + var->length, 8); + for (var = buf->var; var < last_var; + var = (struct efi_var_entry *) + ALIGN((uintptr_t)data + var->length, 8)) { + + data = var->name + u16_strlen(var->name) + 1; + + /* + * Secure boot related and non-volatile variables shall only be + * restored from U-Boot's preseed. + */ + if (!safe && + (efi_auth_var_get_type(var->name, &var->guid) != + EFI_AUTH_VAR_NONE || + !(var->attr & EFI_VARIABLE_NON_VOLATILE))) + continue; + if (!var->length) + continue; + ret = efi_var_mem_ins(var->name, &var->guid, var->attr, + var->length, data, 0, NULL, + var->time); + if (ret != EFI_SUCCESS) + log_err("Failed to set EFI variable %ls\n", var->name); } return EFI_SUCCESS; } @@ -213,7 +222,7 @@ efi_status_t efi_var_from_file(void) log_err("Failed to load EFI variables\n"); goto error; } - if (buf->length != len || efi_var_restore(buf) != EFI_SUCCESS) + if (buf->length != len || efi_var_restore(buf, false) != EFI_SUCCESS) log_err("Invalid EFI variables file\n"); error: free(buf); diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c index ba0874e9e7..a7d305ffbc 100644 --- a/lib/efi_loader/efi_variable.c +++ b/lib/efi_loader/efi_variable.c @@ -426,7 +426,7 @@ efi_status_t efi_init_variables(void)
if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) { ret = efi_var_restore((struct efi_var_file *) - __efi_var_file_begin); + __efi_var_file_begin, true); if (ret != EFI_SUCCESS) log_err("Invalid EFI variable seed\n"); }