lib/utils_wipe.c

   1 /*
   2  * utils_wipe - wipe a device
   3  *
   4  * Copyright (C) 2004-2007, Clemens Fruhwirth <clemens@endorphin.org>
   5  * Copyright (C) 2011-2012, Red Hat, Inc. All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * version 2 as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <stdlib.h>
  24 #include <errno.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27 #include <sys/types.h>
  28 #include <sys/stat.h>
  29 #include <sys/ioctl.h>
  30 #include <fcntl.h>
  31
  32 #include "libcryptsetup.h"
  33 #include "internal.h"
  34
  35 #define MAXIMUM_WIPE_BYTES      1024 * 1024 * 32 /* 32 MiB */
  36
  37 static ssize_t _crypt_wipe_zero(int fd, int bsize, char *buffer,
  38                                 uint64_t offset, uint64_t size)
  39 {
  40         memset(buffer, 0, size);
  41         return write_lseek_blockwise(fd, bsize, buffer, size, offset);
  42 }
  43
  44 static ssize_t _crypt_wipe_random(int fd, int bsize, char *buffer,
  45                                   uint64_t offset, uint64_t size)
  46 {
  47         if (crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL) < 0)
  48                 return -EINVAL;
  49
  50         return write_lseek_blockwise(fd, bsize, buffer, size, offset);
  51 }
  52
  53 /*
  54  * Wipe using Peter Gutmann method described in
  55  * http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
  56  */
  57 static void wipeSpecial(char *buffer, size_t buffer_size, unsigned int turn)
  58 {
  59         unsigned int i;
  60
  61         unsigned char write_modes[][3] = {
  62                 {"\x55\x55\x55"}, {"\xaa\xaa\xaa"}, {"\x92\x49\x24"},
  63                 {"\x49\x24\x92"}, {"\x24\x92\x49"}, {"\x00\x00\x00"},
  64                 {"\x11\x11\x11"}, {"\x22\x22\x22"}, {"\x33\x33\x33"},
  65                 {"\x44\x44\x44"}, {"\x55\x55\x55"}, {"\x66\x66\x66"},
  66                 {"\x77\x77\x77"}, {"\x88\x88\x88"}, {"\x99\x99\x99"},
  67                 {"\xaa\xaa\xaa"}, {"\xbb\xbb\xbb"}, {"\xcc\xcc\xcc"},
  68                 {"\xdd\xdd\xdd"}, {"\xee\xee\xee"}, {"\xff\xff\xff"},
  69                 {"\x92\x49\x24"}, {"\x49\x24\x92"}, {"\x24\x92\x49"},
  70                 {"\x6d\xb6\xdb"}, {"\xb6\xdb\x6d"}, {"\xdb\x6d\xb6"}
  71         };
  72
  73         for(i = 0; i < buffer_size / 3; ++i) {
  74                 memcpy(buffer, write_modes[turn], 3);
  75                 buffer += 3;
  76         }
  77 }
  78
  79 static ssize_t _crypt_wipe_disk(int fd, int bsize, char *buffer,
  80                                 uint64_t offset, uint64_t size)
  81 {
  82         int r;
  83         unsigned int i;
  84         ssize_t written;
  85
  86         for(i = 0; i < 39; ++i) {
  87                 if (i <  5) {
  88                         r = crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL);
  89                 } else if(i >=  5 && i < 32) {
  90                         wipeSpecial(buffer, size, i - 5);
  91                         r = 0;
  92                 } else if(i >= 32 && i < 38) {
  93                         r = crypt_random_get(NULL, buffer, size, CRYPT_RND_NORMAL);
  94                 } else if(i >= 38 && i < 39) {
  95                         memset(buffer, 0xFF, size);
  96                         r = 0;
  97                 }
  98                 if (r < 0)
  99                         return r;
 100
 101                 written = write_lseek_blockwise(fd, bsize, buffer, size, offset);
 102                 if (written < 0 || written != (ssize_t)size)
 103                         return written;
 104         }
 105
 106         /* Rewrite it finally with random */
 107         return _crypt_wipe_random(fd, bsize, buffer, offset, size);
 108 }
 109
 110 static ssize_t _crypt_wipe_ssd(int fd, int bsize, char *buffer,
 111                                uint64_t offset, uint64_t size)
 112 {
 113         // FIXME: for now just rewrite it by random
 114         return _crypt_wipe_random(fd, bsize, buffer, offset, size);
 115 }
 116
 117 int crypt_wipe(struct device *device,
 118                uint64_t offset,
 119                uint64_t size,
 120                crypt_wipe_type type,
 121                int exclusive)
 122 {
 123         struct stat st;
 124         char *buffer;
 125         int devfd, flags, rotational, bsize;
 126         ssize_t written;
 127
 128         if (!size || size % SECTOR_SIZE || (size > MAXIMUM_WIPE_BYTES)) {
 129                 log_dbg("Unsuported wipe size for device %s: %ld.",
 130                         device_path(device), (unsigned long)size);
 131                 return -EINVAL;
 132         }
 133
 134         if (stat(device_path(device), &st) < 0) {
 135                 log_dbg("Device %s not found.", device_path(device));
 136                 return -EINVAL;
 137         }
 138
 139         if (type == CRYPT_WIPE_DISK && S_ISBLK(st.st_mode)) {
 140                 rotational = 0;
 141                 if (!crypt_sysfs_get_rotational(major(st.st_rdev),
 142                                                 minor(st.st_rdev),
 143                                                 &rotational))
 144                         rotational = 1;
 145                 log_dbg("Rotational flag is %d.", rotational);
 146                 if (!rotational)
 147                         type = CRYPT_WIPE_SSD;
 148         }
 149
 150         bsize = device_block_size(device);
 151         if (bsize <= 0)
 152                 return -EINVAL;
 153
 154         buffer = malloc(size);
 155         if (!buffer)
 156                 return -ENOMEM;
 157
 158         flags = O_RDWR | O_DIRECT | O_SYNC;
 159
 160         /* use O_EXCL only for block devices */
 161         if (exclusive && S_ISBLK(st.st_mode))
 162                 flags |= O_EXCL;
 163
 164         devfd = open(device_path(device), flags);
 165         if (devfd == -1) {
 166                 free(buffer);
 167                 return errno ? -errno : -EINVAL;
 168         }
 169
 170         // FIXME: use fixed block size and loop here
 171         switch (type) {
 172                 case CRYPT_WIPE_ZERO:
 173                         written = _crypt_wipe_zero(devfd, bsize, buffer, offset, size);
 174                         break;
 175                 case CRYPT_WIPE_DISK:
 176                         written = _crypt_wipe_disk(devfd, bsize, buffer, offset, size);
 177                         break;
 178                 case CRYPT_WIPE_SSD:
 179                         written = _crypt_wipe_ssd(devfd, bsize, buffer, offset, size);
 180                         break;
 181                 case CRYPT_WIPE_RANDOM:
 182                         written = _crypt_wipe_random(devfd, bsize, buffer, offset, size);
 183                         break;
 184                 default:
 185                         log_dbg("Unsuported wipe type requested: (%d)", type);
 186                         written = -1;
 187         }
 188
 189         close(devfd);
 190         free(buffer);
 191
 192         if (written != (ssize_t)size || written < 0)
 193                 return -EIO;
 194
 195         return 0;
 196 }