tpm2_eventlog: parse vendor_db as EFI_SIGNATURE_DATA

Since 9a47a1e, EV_EFI_VARIABLE_AUTHORITY variables should be parsed
explictly, so here we add support for parsing vendor_db -- which contains
the shim's built-in vendor allowlist [1] -- as EFI_SIGNATURE_DATA, in a
similar way that we do with db and Shim.

Signed-off-by: Sergio Correia <scorreia@redhat.com>

[1] https://github.com/rhboot/shim/blob/afc4955/README.tpm#L16

Author: sergio-correia

lib/tpm2_eventlog_yaml.c

@@ -43,6 +43,8 @@
 #define NAME_SHIM "Shim"
 #define NAME_SHIM_LEN 4
 #define NAME_SECUREBOOT_LEN 10
+#define NAME_VENDOR_DB "vendor_db"
+#define NAME_VENDOR_DB_LEN 9
 
 static void guid_unparse_lower(EFI_GUID guid, char guid_buf[37]) {
 
@@ -646,8 +648,9 @@ static bool yaml_uefi_var(UEFI_VARIABLE_DATA *data, size_t size, UINT32 type,
                 }
                 return true;
             } else if ((strlen(ret) == NAME_DB_LEN && strncmp(ret, NAME_DB, NAME_DB_LEN) == 0) ||
-                       (strlen(ret) == NAME_SHIM_LEN && strncmp(ret, NAME_SHIM, NAME_SHIM_LEN) == 0)) {
-                /* db and Shim will be parsed as EFI_SIGNATURE_DATA */
+                       (strlen(ret) == NAME_SHIM_LEN && strncmp(ret, NAME_SHIM, NAME_SHIM_LEN) == 0) ||
+                       (strlen(ret) == NAME_VENDOR_DB_LEN && strncmp(ret, NAME_VENDOR_DB, NAME_VENDOR_DB_LEN) == 0))  {
+                /* db, Shim and vendor_db will be parsed as EFI_SIGNATURE_DATA */
                 free(ret);
                 tpm2_tool_output("    VariableData:\n");
                 EFI_SIGNATURE_DATA *s= (EFI_SIGNATURE_DATA *)&data->UnicodeName[