lib/luks1/keyencryption.c

   1 /*
   2  * LUKS - Linux Unified Key Setup
   3  *
   4  * Copyright (C) 2004-2006, Clemens Fruhwirth <clemens@endorphin.org>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <string.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <ctype.h>
  24 #include <inttypes.h>
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <sys/ioctl.h>
  28 #include <sys/mman.h>
  29 #include <sys/utsname.h>
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #include <errno.h>
  33 #include <signal.h>
  34
  35 #include "luks.h"
  36 #include "internal.h"
  37
  38 #define div_round_up(a,b) ({          \
  39         typeof(a) __a = (a);          \
  40         typeof(b) __b = (b);          \
  41         (__a - 1) / __b + 1;          \
  42 })
  43
  44 static inline int round_up_modulo(int x, int m) {
  45         return div_round_up(x, m) * m;
  46 }
  47
  48 static const char *cleaner_name=NULL;
  49 static uint64_t cleaner_size = 0;
  50 static int devfd=-1;
  51
  52 static int setup_mapping(const char *cipher, const char *name,
  53                          const char *device,
  54                          struct volume_key *vk,
  55                          unsigned int sector, size_t srcLength,
  56                          int mode, struct crypt_device *ctx)
  57 {
  58         int device_sector_size = sector_size_for_device(device);
  59         struct crypt_dm_active_device dmd = {
  60                 .device = device,
  61                 .cipher = cipher,
  62                 .uuid   = NULL,
  63                 .vk     = vk,
  64                 .offset = sector,
  65                 .iv_offset = 0,
  66                 .size   = 0,
  67                 .flags  = (mode == O_RDONLY) ? CRYPT_ACTIVATE_READONLY : 0
  68         };
  69
  70         /*
  71          * we need to round this to nearest multiple of the underlying
  72          * device's sector size, otherwise the mapping will be refused.
  73          */
  74         if(device_sector_size < 0) {
  75                 log_err(ctx, _("Unable to obtain sector size for %s"), device);
  76                 return -EINVAL;
  77         }
  78
  79         dmd.size = round_up_modulo(srcLength,device_sector_size)/SECTOR_SIZE;
  80         cleaner_size = dmd.size;
  81
  82         return dm_create_device(name, "TEMP", &dmd, 0);
  83 }
  84
  85 static void sigint_handler(int sig __attribute__((unused)))
  86 {
  87         if(devfd >= 0)
  88                 close(devfd);
  89         devfd = -1;
  90         if(cleaner_name)
  91                 dm_remove_device(cleaner_name, 1, cleaner_size);
  92
  93         signal(SIGINT, SIG_DFL);
  94         kill(getpid(), SIGINT);
  95 }
  96
  97 static const char *_error_hint(char *cipherMode, size_t keyLength)
  98 {
  99         const char *hint= "";
 100
 101         if (!strncmp(cipherMode, "xts", 3) && (keyLength != 256 && keyLength != 512))
 102                 hint = _("Key size in XTS mode must be 256 or 512 bits.\n");
 103
 104         return hint;
 105 }
 106
 107 /* This function is not reentrant safe, as it installs a signal
 108    handler and global vars for cleaning */
 109 static int LUKS_endec_template(char *src, size_t srcLength,
 110                                struct luks_phdr *hdr,
 111                                struct volume_key *vk,
 112                                const char *device,
 113                                unsigned int sector,
 114                                ssize_t (*func)(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
 124         if(dmDir == NULL) {
 125                 log_err(ctx, _("Failed to obtain device mapper directory."));
 126                 return -1;
 127         }
 128         if(asprintf(&name,"temporary-cryptsetup-%d",getpid())               == -1 ||
 129            asprintf(&fullpath,"%s/%s",dmDir,name)                           == -1 ||
 130            asprintf(&dmCipherSpec,"%s-%s",hdr->cipherName, hdr->cipherMode) == -1) {
 131                 r = -ENOMEM;
 132                 goto out1;
 133         }
 134
 135         signal(SIGINT, sigint_handler);
 136         cleaner_name = name;
 137
 138         r = setup_mapping(dmCipherSpec, name, device,
 139                           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, 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,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                             const char *device,
 183                             unsigned int sector,
 184                             struct crypt_device *ctx)
 185 {
 186         return LUKS_endec_template(src,srcLength,hdr,vk, device,
 187                                    sector, write_blockwise, O_RDWR, ctx);
 188 }
 189
 190 int LUKS_decrypt_from_storage(char *dst, size_t dstLength,
 191                               struct luks_phdr *hdr,
 192                               struct volume_key *vk,
 193                               const char *device,
 194                               unsigned int sector,
 195                               struct crypt_device *ctx)
 196 {
 197         return LUKS_endec_template(dst,dstLength,hdr,vk, device,
 198                                    sector, read_blockwise, O_RDONLY, ctx);
 199 }