1. Optimization for WIMBOOT mode.

2. Add WIMBOOT for UEFI mode.

wimboot/wimboot-2.7.3/src/cookie.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/**
+ * @file
+ *
+ * Stack cookie
+ *
+ */
+
+#include "wimboot.h"
+
+/** Stack cookie */
+unsigned long __stack_chk_guard;
+
+/**
+ * Construct stack cookie value
+ *
+ */
+static __attribute__ (( noinline )) unsigned long make_cookie ( void ) {
+	union {
+		struct {
+			uint32_t eax;
+			uint32_t edx;
+		} __attribute__ (( packed ));
+		unsigned long tsc;
+	} u;
+	unsigned long cookie;
+
+	/* We have no viable source of entropy.  Use the CPU timestamp
+	 * counter, which will have at least some minimal randomness
+	 * in the low bits by the time we are invoked.
+	 */
+	__asm__ ( "rdtsc" : "=a" ( u.eax ), "=d" ( u.edx ) );
+	cookie = u.tsc;
+
+	/* Ensure that the value contains a NUL byte, to act as a
+	 * runaway string terminator.  Construct the NUL using a shift
+	 * rather than a mask, to avoid losing valuable entropy in the
+	 * lower-order bits.
+	 */
+	cookie <<= 8;
+
+	return cookie;
+}
+
+/**
+ * Initialise stack cookie
+ *
+ * This function must not itself use stack guard
+ */
+void init_cookie ( void ) {
+
+	/* Set stack cookie value
+	 *
+	 * This function must not itself use stack protection, since
+	 * the change in the stack guard value would trigger a false
+	 * positive.
+	 *
+	 * There is unfortunately no way to annotate a function to
+	 * exclude the use of stack protection.  We must therefore
+	 * rely on correctly anticipating the compiler's decision on
+	 * the use of stack protection.
+	 */
+	__stack_chk_guard = make_cookie();
+}
+
+/**
+ * Abort on stack check failure
+ *
+ */
+void __stack_chk_fail ( void ) {
+
+	/* Abort program */
+	die ( "Stack check failed\n" );
+}