lib/luks1/keyencryption.c

   1 /*
   2  * LUKS - Linux Unified Key Setup
   3  *
   4  * Copyright (C) 2004-2006, Clemens Fruhwirth <clemens@endorphin.org>
   5  * Copyright (C) 2009-2012, 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 <string.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <ctype.h>
  25 #include <inttypes.h>
  26 #include <sys/types.h>
  27 #include <sys/stat.h>
  28 #include <sys/ioctl.h>
  29 #include <sys/mman.h>
  30 #include <sys/utsname.h>
  31 #include <fcntl.h>
  32 #include <unistd.h>
  33 #include <errno.h>
  34 #include <signal.h>
  35
  36 #include "luks.h"
  37 #include "internal.h"
  38
  39 #define div_round_up(a,b) ({          \
  40         typeof(a) __a = (a);          \
  41         typeof(b) __b = (b);          \
  42         (__a - 1) / __b + 1;          \
  43 })
  44
  45 static inline int round_up_modulo(int x, int m) {
  46         return div_round_up(x, m) * m;
  47 }
  48
  49 static const char *cleaner_name=NULL;
  50 static uint64_t cleaner_size = 0;
  51 static int devfd=-1;
  52
  53 static int setup_mapping(const char *cipher, const char *name,
  54                          const char *device,
  55                          struct volume_key *vk,
  56                          unsigned int sector, size_t srcLength,
  57                          int mode, struct crypt_device *ctx)
  58 {
  59         int device_sector_size = sector_size_for_device(device);
  60         struct crypt_dm_active_device dmd = {
  61                 .device = device,
  62                 .cipher = cipher,
  63                 .uuid   = NULL,
  64                 .vk     = vk,
  65                 .offset = sector,
  66                 .iv_offset = 0,
  67                 .size   = 0,
  68                 .flags  = (mode == O_RDONLY) ? CRYPT_ACTIVATE_READONLY : 0
  69         };
  70
  71         /*
  72          * we need to round this to nearest multiple of the underlying
  73          * device's sector size, otherwise the mapping will be refused.
  74          */
  75         if(device_sector_size < 0) {
  76                 log_err(ctx, _("Unable to obtain sector size for %s"), device);
  77                 return -EINVAL;
  78         }
  79
  80         dmd.size = round_up_modulo(srcLength,device_sector_size)/SECTOR_SIZE;
  81         cleaner_size = dmd.size;
  82
  83         return dm_create_device(name, "TEMP", &dmd, 0);
  84 }
  85
  86 static void sigint_handler(int sig __attribute__((unused)))
  87 {
  88         if(devfd >= 0)
  89                 close(devfd);
  90         devfd = -1;
  91         if(cleaner_name)
  92                 dm_remove_device(cleaner_name, 1, cleaner_size);
  93
  94         signal(SIGINT, SIG_DFL);
  95         kill(getpid(), SIGINT);
  96 }
  97
  98 static const char *_error_hint(char *cipherMode, size_t keyLength)
  99 {
 100         const char *hint= "";
 101
 102         if (!strncmp(cipherMode, "xts", 3) && (keyLength != 256 && keyLength != 512))
 103                 hint = _("Key size in XTS mode must be 256 or 512 bits.\n");
 104
 105         return hint;
 106 }
 107
 108 /* This function is not reentrant safe, as it installs a signal
 109    handler and global vars for cleaning */
 110 static int LUKS_endec_template(char *src, size_t srcLength,
 111                                struct luks_phdr *hdr,
 112                                struct volume_key *vk,
 113                                const char *device,
 114                                unsigned int sector,
 115                                ssize_t (*func)(int, void *, size_t),
 116                                int mode,
 117                                struct crypt_device *ctx)
 118 {
 119         char *name = NULL;
 120         char *fullpath = NULL;
 121         char *dmCipherSpec = NULL;
 122         const char *dmDir = dm_get_dir();
 123         int r = -1;
 124
 125         if(dmDir == NULL) {
 126                 log_err(ctx, _("Failed to obtain device mapper directory."));
 127                 return -1;
 128         }
 129         if(asprintf(&name,"temporary-cryptsetup-%d",getpid())               == -1 ||
 130            asprintf(&fullpath,"%s/%s",dmDir,name)                           == -1 ||
 131            asprintf(&dmCipherSpec,"%s-%s",hdr->cipherName, hdr->cipherMode) == -1) {
 132                 r = -ENOMEM;
 133                 goto out1;
 134         }
 135
 136         signal(SIGINT, sigint_handler);
 137         cleaner_name = name;
 138
 139         r = setup_mapping(dmCipherSpec, name, device,
 140                           vk, sector, srcLength, mode, ctx);
 141         if(r < 0) {
 142                 log_err(ctx, _("Failed to setup dm-crypt key mapping for device %s.\n"
 143                         "Check that kernel supports %s cipher (check syslog for more info).\n%s"),
 144                         device, dmCipherSpec,
 145                         _error_hint(hdr->cipherMode, vk->keylength * 8));
 146                 r = -EIO;
 147                 goto out1;
 148         }
 149
 150         devfd = open(fullpath, mode | O_DIRECT | O_SYNC);  /* devfd is a global var */
 151         if(devfd == -1) {
 152                 log_err(ctx, _("Failed to open temporary keystore device.\n"));
 153                 r = -EIO;
 154                 goto out2;
 155         }
 156
 157         r = func(devfd,src,srcLength);
 158         if(r < 0) {
 159                 log_err(ctx, _("Failed to access temporary keystore device.\n"));
 160                 r = -EIO;
 161                 goto out3;
 162         }
 163
 164         r = 0;
 165  out3:
 166         close(devfd);
 167         devfd = -1;
 168  out2:
 169         dm_remove_device(cleaner_name, 1, cleaner_size);
 170  out1:
 171         signal(SIGINT, SIG_DFL);
 172         cleaner_name = NULL;
 173         cleaner_size = 0;
 174         free(dmCipherSpec);
 175         free(fullpath);
 176         free(name);
 177         return r;
 178 }
 179
 180 int LUKS_encrypt_to_storage(char *src, size_t srcLength,
 181                             struct luks_phdr *hdr,
 182                             struct volume_key *vk,
 183                             const char *device,
 184                             unsigned int sector,
 185                             struct crypt_device *ctx)
 186 {
 187         return LUKS_endec_template(src,srcLength,hdr,vk, device,
 188                                    sector, write_blockwise, O_RDWR, ctx);
 189 }
 190
 191 int LUKS_decrypt_from_storage(char *dst, size_t dstLength,
 192                               struct luks_phdr *hdr,
 193                               struct volume_key *vk,
 194                               const char *device,
 195                               unsigned int sector,
 196                               struct crypt_device *ctx)
 197 {
 198         return LUKS_endec_template(dst,dstLength,hdr,vk, device,
 199                                    sector, read_blockwise, O_RDONLY, ctx);
 200 }