1 files changed, 122 insertions, 0 deletions
diff --git a/lib/utils_safe_memory.c b/lib/utils_safe_memory.c
new file mode 100644
index 0000000..b161369
--- /dev/null
+++ b/lib/utils_safe_memory.c
@@ -0,0 +1,122 @@
+/*
+ * utils_safe_memory - safe memory helpers
+ *
+ * Copyright (C) 2009-2023 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2009-2023 Milan Broz
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/mman.h>
+#include "libcryptsetup.h"
+
+struct safe_allocation {
+	size_t size;
+	bool locked;
+	char data[0] __attribute__((aligned(8)));
+};
+#define OVERHEAD offsetof(struct safe_allocation, data)
+
+/*
+ * Replacement for memset(s, 0, n) on stack that can be optimized out
+ * Also used in safe allocations for explicit memory wipe.
+ */
+void crypt_safe_memzero(void *data, size_t size)
+{
+	if (!data)
+		return;
+
+#ifdef HAVE_EXPLICIT_BZERO
+	explicit_bzero(data, size);
+#else
+	volatile uint8_t *p = (volatile uint8_t *)data;
+
+	while(size--)
+		*p++ = 0;
+#endif
+}
+
+/* safe allocations */
+void *crypt_safe_alloc(size_t size)
+{
+	struct safe_allocation *alloc;
+
+	if (!size || size > (SIZE_MAX - OVERHEAD))
+		return NULL;
+
+	alloc = malloc(size + OVERHEAD);
+	if (!alloc)
+		return NULL;
+
+	crypt_safe_memzero(alloc, size + OVERHEAD);
+	alloc->size = size;
+
+	/* Ignore failure if it is over limit. */
+	if (!mlock(alloc, size + OVERHEAD))
+		alloc->locked = true;
+
+	/* coverity[leaked_storage] */
+	return &alloc->data;
+}
+
+void crypt_safe_free(void *data)
+{
+	struct safe_allocation *alloc;
+	volatile size_t *s;
+	void *p;
+
+	if (!data)
+		return;
+
+	p = (char *)data - OVERHEAD;
+	alloc = (struct safe_allocation *)p;
+
+	crypt_safe_memzero(data, alloc->size);
+
+	if (alloc->locked) {
+		munlock(alloc, alloc->size + OVERHEAD);
+		alloc->locked = false;
+	}
+
+	s = (volatile size_t *)&alloc->size;
+	*s = 0x55aa55aa;
+	free(alloc);
+}
+
+void *crypt_safe_realloc(void *data, size_t size)
+{
+	struct safe_allocation *alloc;
+	void *new_data;
+	void *p;
+
+	new_data = crypt_safe_alloc(size);
+
+	if (new_data && data) {
+
+		p = (char *)data - OVERHEAD;
+		alloc = (struct safe_allocation *)p;
+
+		if (size > alloc->size)
+			size = alloc->size;
+
+		memcpy(new_data, data, size);
+	}
+
+	crypt_safe_free(data);
+	return new_data;
+}