If device is not rotational, do not use Gutmann wipe method.

git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@615 36d66b0a-2a48-0410-832c-cd162a569da5

lib/utils_wipe.c

@@ -0,0 +1,172 @@
+/*
+ * utils_wipe - wipe a device
+ *
+ * Copyright (C) 2004-2007, Clemens Fruhwirth <clemens@endorphin.org>
+ * Copyright (C) 2011, Red Hat, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+
+#include "libcryptsetup.h"
+#include "internal.h"
+
+#define MAXIMUM_WIPE_BYTES	1024 * 1024 * 32 /* 32 MiB */
+
+static ssize_t _crypt_wipe_zero(int fd, char *buffer, uint64_t offset, uint64_t size)
+{
+	memset(buffer, 0, size);
+	return write_lseek_blockwise(fd, buffer, size, offset);
+}
+
+/*
+ * Wipe using Peter Gutmann method described in
+ * http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
+ */
+static void wipeSpecial(char *buffer, size_t buffer_size, unsigned int turn)
+{
+	unsigned int i;
+
+	unsigned char write_modes[][3] = {
+		{"\x55\x55\x55"}, {"\xaa\xaa\xaa"}, {"\x92\x49\x24"},
+		{"\x49\x24\x92"}, {"\x24\x92\x49"}, {"\x00\x00\x00"},
+		{"\x11\x11\x11"}, {"\x22\x22\x22"}, {"\x33\x33\x33"},
+		{"\x44\x44\x44"}, {"\x55\x55\x55"}, {"\x66\x66\x66"},
+		{"\x77\x77\x77"}, {"\x88\x88\x88"}, {"\x99\x99\x99"},
+		{"\xaa\xaa\xaa"}, {"\xbb\xbb\xbb"}, {"\xcc\xcc\xcc"},
+		{"\xdd\xdd\xdd"}, {"\xee\xee\xee"}, {"\xff\xff\xff"},
+		{"\x92\x49\x24"}, {"\x49\x24\x92"}, {"\x24\x92\x49"},
+		{"\x6d\xb6\xdb"}, {"\xb6\xdb\x6d"}, {"\xdb\x6d\xb6"}
+	};
+
+	for(i = 0; i < buffer_size / 3; ++i) {
+		memcpy(buffer, write_modes[turn], 3);
+		buffer += 3;
+	}
+}
+
+static ssize_t _crypt_wipe_disk(int fd, char *buffer, uint64_t offset, uint64_t size)
+{
+	unsigned int i;
+	ssize_t written;
+
+	for(i = 0; i < 39; ++i) {
+		if                (i <  5) crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL);
+		else if(i >=  5 && i < 32) wipeSpecial(buffer, size, i - 5);
+		else if(i >= 32 && i < 38) crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL);
+		else if(i >= 38 && i < 39) memset(buffer, 0xFF, size);
+
+		written = write_lseek_blockwise(fd, buffer, size, offset);
+		if (written < 0 || written != size)
+			return written;
+	}
+
+	return written;
+}
+
+static ssize_t _crypt_wipe_random(int fd, char *buffer, uint64_t offset, uint64_t size)
+{
+	crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL);
+	return write_lseek_blockwise(fd, buffer, size, offset);
+}
+
+static ssize_t _crypt_wipe_ssd(int fd, char *buffer, uint64_t offset, uint64_t size)
+{
+	// FIXME: for now just rewrite it by random
+	return _crypt_wipe_random(fd, buffer, offset, size);
+}
+
+int crypt_wipe(const char *device,
+	       uint64_t offset,
+	       uint64_t size,
+	       crypt_wipe_type type,
+	       int exclusive)
+{
+	struct stat st;
+	char *buffer;
+	int devfd, flags, rotational;
+	ssize_t written;
+
+	if (!size || size % SECTOR_SIZE || (size > MAXIMUM_WIPE_BYTES)) {
+		log_dbg("Unsuported wipe size for device %s: %ld.",
+			device, (unsigned long)size);
+		return -EINVAL;
+	}
+
+	if (stat(device, &st) < 0) {
+		log_dbg("Device %s not found.", device);
+		return -EINVAL;
+	}
+
+	if (type == CRYPT_WIPE_DISK) {
+		if (!crypt_sysfs_get_rotational(major(st.st_rdev),
+						minor(st.st_rdev),
+						&rotational))
+			rotational = 1;
+		log_dbg("Rotational flag is %d.", rotational);
+		if (!rotational)
+			type = CRYPT_WIPE_SSD;
+	}
+
+	buffer = malloc(size);
+	if (!buffer)
+		return -ENOMEM;
+
+	flags = O_WRONLY | O_DIRECT | O_SYNC;
+
+	/* use O_EXCL only for block devices */
+	if (exclusive && S_ISBLK(st.st_mode))
+		flags |= O_EXCL;
+
+	devfd = open(device, flags);
+	if (devfd == -1) {
+		free(buffer);
+		return errno == EBUSY ? -EBUSY : -EINVAL;
+	}
+
+	// FIXME: use fixed block size and loop here
+	switch (type) {
+		case CRYPT_WIPE_ZERO:
+			written = _crypt_wipe_zero(devfd, buffer, offset, size);
+			break;
+		case CRYPT_WIPE_DISK:
+			written = _crypt_wipe_disk(devfd, buffer, offset, size);
+		case CRYPT_WIPE_SSD:
+			written = _crypt_wipe_ssd(devfd, buffer, offset, size);
+			break;
+		case CRYPT_WIPE_RANDOM:
+			written = _crypt_wipe_random(devfd, buffer, offset, size);
+		default:
+			log_dbg("Unsuported wipe type requested: (%d)", type);
+			written = -1;
+	}
+
+	close(devfd);
+	free(buffer);
+
+	if (written != size || written < 0)
+		return -EIO;
+
+	return 0;
+}