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                          int bsize, struct volume_key *vk,
  55                          unsigned int sector, size_t srcLength,
  56                          int mode, struct crypt_device *ctx)
  57 {
  58         struct device *device = crypt_metadata_device(ctx);
  59         struct crypt_dm_active_device dmd = {
  60                 .target = DM_CRYPT,
  61                 .uuid   = NULL,
  62                 .size   = round_up_modulo(srcLength, bsize) / SECTOR_SIZE,
  63                 .flags  = CRYPT_ACTIVATE_PRIVATE,
  64                 .data_device = device,
  65                 .u.crypt = {
  66                         .cipher = cipher,
  67                         .vk     = vk,
  68                         .offset = sector,
  69                         .iv_offset = 0,
  70                 }
  71         };
  72         int r;
  73
  74         if (mode == O_RDONLY)
  75                 dmd.flags |= CRYPT_ACTIVATE_READONLY;
  76
  77         r = device_block_adjust(ctx, dmd.data_device, DEV_OK,
  78                                 dmd.u.crypt.offset, &dmd.size, &dmd.flags);
  79         if (r < 0)
  80                 return r;
  81
  82         cleaner_size = dmd.size;
  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                                unsigned int sector,
 114                                ssize_t (*func)(int, int, void *, size_t),
 115                                int mode,
 116                                struct crypt_device *ctx)
 117 {
 118         char *name = NULL;
 119         char *fullpath = NULL;
 120         char *dmCipherSpec = NULL;
 121         const char *dmDir = dm_get_dir();
 122         int r = -1;
 123         int bsize = device_block_size(crypt_metadata_device(ctx));
 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, bsize, vk, sector, srcLength, mode, ctx);
 140         if(r < 0) {
 141                 log_err(ctx, _("Failed to setup dm-crypt key mapping for device %s.\n"
 142                         "Check that kernel supports %s cipher (check syslog for more info).\n%s"),
 143                         device_path(crypt_metadata_device(ctx)), dmCipherSpec,
 144                         _error_hint(hdr->cipherMode, vk->keylength * 8));
 145                 r = -EIO;
 146                 goto out1;
 147         }
 148
 149         devfd = open(fullpath, mode | O_DIRECT | O_SYNC);  /* devfd is a global var */
 150         if(devfd == -1) {
 151                 log_err(ctx, _("Failed to open temporary keystore device.\n"));
 152                 r = -EIO;
 153                 goto out2;
 154         }
 155
 156         r = func(devfd, bsize, src, srcLength);
 157         if(r < 0) {
 158                 log_err(ctx, _("Failed to access temporary keystore device.\n"));
 159                 r = -EIO;
 160                 goto out3;
 161         }
 162
 163         r = 0;
 164  out3:
 165         close(devfd);
 166         devfd = -1;
 167  out2:
 168         dm_remove_device(cleaner_name, 1, cleaner_size);
 169  out1:
 170         signal(SIGINT, SIG_DFL);
 171         cleaner_name = NULL;
 172         cleaner_size = 0;
 173         free(dmCipherSpec);
 174         free(fullpath);
 175         free(name);
 176         return r;
 177 }
 178
 179 int LUKS_encrypt_to_storage(char *src, size_t srcLength,
 180                             struct luks_phdr *hdr,
 181                             struct volume_key *vk,
 182                             unsigned int sector,
 183                             struct crypt_device *ctx)
 184 {
 185         return LUKS_endec_template(src, srcLength, hdr, vk, sector,
 186                                    write_blockwise, O_RDWR, ctx);
 187 }
 188
 189 int LUKS_decrypt_from_storage(char *dst, size_t dstLength,
 190                               struct luks_phdr *hdr,
 191                               struct volume_key *vk,
 192                               unsigned int sector,
 193                               struct crypt_device *ctx)
 194 {
 195         return LUKS_endec_template(dst, dstLength, hdr, vk, sector,
 196                                    read_blockwise, O_RDONLY, ctx);
 197 }