Add mechanism for testing invalid Munge credential

src/plugins/auth/munge/auth_munge.c

@@ -107,8 +107,8 @@ const uint32_t plugin_version   = 10;
 const uint32_t min_plug_version = 10; /* minimum version accepted */
 
 static int plugin_errno = SLURM_SUCCESS;
-
 static int host_list_idx = -1;
+static int bad_cred_test = -1;
 
 
 enum {
@@ -154,12 +154,17 @@ static void           _print_cred_info(munge_info_t *mi);
 static void           _print_cred(munge_ctx_t ctx);
 static int            _decode_cred(slurm_auth_credential_t *c, char *socket);
 
-
 /*
  *  Munge plugin initialization
  */
 int init ( void )
 {
+	char *fail_test_env = getenv("SLURM_MUNGE_AUTH_FAIL_TEST");
+	if (fail_test_env)
+		bad_cred_test = atoi(fail_test_env);
+	else
+		bad_cred_test = 0;
+
 	host_list_idx = arg_idx_by_name( slurm_auth_get_arg_desc(),
 			                 ARG_HOST_LIST );
 	if (host_list_idx == -1)
@@ -240,6 +245,9 @@ slurm_auth_create( void *argv[], char *socket )
 		xfree( cred );
 		cred = NULL;
 		plugin_errno = e + MUNGE_ERRNO_OFFSET;
+	} else if ((bad_cred_test > 0) && cred->m_str) {
+		int i = ((int) time(NULL)) % strlen(cred->m_str);
+		cred->m_str[i]++;	/* random position in credential */
 	}
 
 	xsignal(SIGALRM, ohandler);
@@ -542,7 +550,6 @@ _decode_cred(slurm_auth_credential_t *c, char *socket)
 			_print_cred(ctx);
 			if (e == EMUNGE_CRED_REWOUND)
 				error("Check for out of sync clocks");
-
 			c->cr_errno = e + MUNGE_ERRNO_OFFSET;
 #ifdef MULTIPLE_SLURMD
 		} else {