lib/verity/verity.c

   1 /*
   2  * dm-verity volume handling
   3  *
   4  * Copyright (C) 2012, Red Hat, Inc. All rights reserved.
   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 <errno.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <stdint.h>
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <fcntl.h>
  28 #include <netinet/in.h>
  29 #include <uuid/uuid.h>
  30
  31 #include "libcryptsetup.h"
  32 #include "verity.h"
  33 #include "internal.h"
  34
  35 #define VERITY_SIGNATURE "verity\0\0"
  36
  37 #define NEW_SB 1
  38
  39 #ifndef NEW_SB
  40 struct verity_sb {
  41         uint8_t signature[8];
  42         uint8_t version;
  43         uint8_t data_block_bits;
  44         uint8_t hash_block_bits;
  45         uint8_t pad1[1];
  46         uint16_t salt_size;
  47         uint8_t pad2[2];
  48         uint32_t data_blocks_hi;
  49         uint32_t data_blocks_lo;
  50         uint8_t algorithm[16];
  51         uint8_t salt[384];
  52         uint8_t pad3[88];
  53 };
  54 #else
  55 struct verity_sb {
  56         uint8_t  signature[8];  /* "verity\0\0" */
  57         uint32_t version;       /* superblock version */
  58         uint32_t hash_type;     /* 0 - Chrome OS, 1 - normal */
  59         uint8_t  uuid[16];      /* UUID of hash device */
  60         uint8_t  algorithm[32];/* hash algorithm name */
  61         uint64_t data_block_size; /* data block in bytes */
  62         uint64_t hash_block_size; /* hash block in bytes */
  63         uint64_t data_blocks;   /* number of data blocks */
  64         uint16_t salt_size;     /* salt size */
  65         uint8_t  _pad1[6];
  66         uint8_t  salt[256];     /* salt */
  67         uint8_t  _pad2[160];
  68 } __attribute__((packed));
  69 #endif
  70
  71 /* Read verity superblock from disk */
  72 int VERITY_read_sb(struct crypt_device *cd,
  73                    const char *device,
  74                    uint64_t sb_offset,
  75                    char **uuid_string,
  76                    struct crypt_params_verity *params)
  77 {
  78         struct verity_sb sb = {};
  79         ssize_t hdr_size = sizeof(struct verity_sb);
  80         int devfd = 0, sb_version;
  81 #ifndef NEW_SB
  82         uint64_t sb_data_blocks;
  83 #endif
  84         log_dbg("Reading VERITY header of size %u on device %s, offset %" PRIu64 ".",
  85                 sizeof(struct verity_sb), device, sb_offset);
  86
  87         if (params->flags & CRYPT_VERITY_NO_HEADER) {
  88                 log_err(cd, _("Verity device doesn't use on-disk header.\n"), device);
  89                 return -EINVAL;
  90         }
  91
  92         if (sb_offset % 512) {
  93                 log_err(cd, _("Unsupported VERITY hash offset.\n"));
  94                 return -EINVAL;
  95         }
  96
  97         devfd = open(device ,O_RDONLY | O_DIRECT);
  98         if(devfd == -1) {
  99                 log_err(cd, _("Cannot open device %s.\n"), device);
 100                 return -EINVAL;
 101         }
 102
 103         if(lseek(devfd, sb_offset, SEEK_SET) < 0 ||
 104            read_blockwise(devfd, &sb, hdr_size) < hdr_size) {
 105                 close(devfd);
 106                 return -EIO;
 107         }
 108         close(devfd);
 109
 110         if (memcmp(sb.signature, VERITY_SIGNATURE, sizeof(sb.signature))) {
 111                 log_err(cd, _("Device %s is not a valid VERITY device.\n"), device);
 112                 return -EINVAL;
 113         }
 114 #ifndef NEW_SB
 115         if (sb.version > 1) {
 116                 log_err(cd, _("Unsupported VERITY version %d.\n"), sb.version);
 117                 return -EINVAL;
 118         }
 119
 120         if (sb.data_block_bits < 9 || sb.data_block_bits >= 31 ||
 121             sb.hash_block_bits < 9 || sb.hash_block_bits >= 31 ||
 122             !memchr(sb.algorithm, 0, sizeof(sb.algorithm)) ||
 123             ntohs(sb.salt_size) > 256) {
 124                 log_err(cd, _("VERITY header corrupted.\n"));
 125                 return -EINVAL;
 126         }
 127
 128         sb_data_blocks = ((uint64_t)ntohl(sb.data_blocks_hi) << 31 << 1) |
 129                                 ntohl(sb.data_blocks_lo);
 130
 131         params->hash_name = strdup((const char*)sb.algorithm);
 132         if (!params->hash_name)
 133                 return -ENOMEM;
 134         params->data_block_size = 1 << sb.data_block_bits;
 135         params->hash_block_size = 1 << sb.hash_block_bits;
 136         params->data_size = sb_data_blocks;
 137         params->salt_size = ntohs(sb.salt_size);
 138         params->salt = malloc(params->salt_size);
 139         if (!params->salt)
 140                 return -ENOMEM;
 141         memcpy(CONST_CAST(char*)params->salt, sb.salt, params->salt_size);
 142         params->hash_type = sb.version;
 143 #else
 144         sb_version = le32_to_cpu(sb.version);
 145         if (sb_version != 1) {
 146                 log_err(cd, _("Unsupported VERITY version %d.\n"), sb_version);
 147                 return -EINVAL;
 148         }
 149         params->hash_type = le32_to_cpu(sb.hash_type);
 150         if (params->hash_type > VERITY_MAX_HASH_TYPE) {
 151                 log_err(cd, _("Unsupported VERITY hash type %d.\n"), params->hash_type);
 152                 return -EINVAL;
 153         }
 154
 155         params->data_block_size = le64_to_cpu(sb.data_block_size);
 156         params->hash_block_size = le64_to_cpu(sb.hash_block_size);
 157         if (VERITY_BLOCK_SIZE_OK(params->data_block_size) ||
 158             VERITY_BLOCK_SIZE_OK(params->hash_block_size)) {
 159                 log_err(cd, _("Unsupported VERITY block size.\n"));
 160                 return -EINVAL;
 161         }
 162         params->data_size = le64_to_cpu(sb.data_blocks);
 163
 164         params->hash_name = strndup((const char*)sb.algorithm, sizeof(sb.algorithm));
 165         if (!params->hash_name)
 166                 return -ENOMEM;
 167         if (crypt_hash_size(params->hash_name) <= 0) {
 168                 log_err(cd, _("Hash algorithm %s not supported.\n"),
 169                         params->hash_name);
 170                 free(CONST_CAST(char*)params->hash_name);
 171                 return -EINVAL;
 172         }
 173
 174         params->salt_size = le16_to_cpu(sb.salt_size);
 175         if (params->salt_size > sizeof(sb.salt)) {
 176                 log_err(cd, _("VERITY header corrupted.\n"));
 177                 free(CONST_CAST(char*)params->hash_name);
 178                 return -EINVAL;
 179         }
 180         params->salt = malloc(params->salt_size);
 181         if (!params->salt) {
 182                 free(CONST_CAST(char*)params->hash_name);
 183                 return -ENOMEM;
 184         }
 185         memcpy(CONST_CAST(char*)params->salt, sb.salt, params->salt_size);
 186
 187         if ((*uuid_string = malloc(40)))
 188                 uuid_unparse(sb.uuid, *uuid_string);
 189 #endif
 190         params->hash_area_offset = sb_offset;
 191         return 0;
 192 }
 193
 194 /* Write verity superblock to disk */
 195 int VERITY_write_sb(struct crypt_device *cd,
 196                    const char *device,
 197                    uint64_t sb_offset,
 198                    const char *uuid_string,
 199                    struct crypt_params_verity *params)
 200 {
 201         struct verity_sb sb = {};
 202         ssize_t hdr_size = sizeof(struct verity_sb);
 203         uuid_t uuid;
 204         int r, devfd = 0;
 205
 206         log_dbg("Updating VERITY header of size %u on device %s, offset %" PRIu64 ".",
 207                 sizeof(struct verity_sb), device, sb_offset);
 208
 209         if (!uuid_string || uuid_parse(uuid_string, uuid) == -1) {
 210                 log_err(cd, _("Wrong VERITY UUID format provided.\n"), device);
 211                 return -EINVAL;
 212         }
 213
 214         if (params->flags & CRYPT_VERITY_NO_HEADER) {
 215                 log_err(cd, _("Verity device doesn't use on-disk header.\n"), device);
 216                 return -EINVAL;
 217         }
 218
 219         devfd = open(device, O_RDWR | O_DIRECT);
 220         if(devfd == -1) {
 221                 log_err(cd, _("Cannot open device %s.\n"), device);
 222                 return -EINVAL;
 223         }
 224
 225         memcpy(&sb.signature, VERITY_SIGNATURE, sizeof(sb.signature));
 226 #ifndef NEW_SB
 227         sb.version = params->hash_type;
 228         sb.data_block_bits = ffs(params->data_block_size) - 1;
 229         sb.hash_block_bits = ffs(params->hash_block_size) - 1;
 230         sb.salt_size = htons(params->salt_size);
 231         sb.data_blocks_hi = htonl(params->data_size >> 31 >> 1);
 232         sb.data_blocks_lo = htonl(params->data_size & 0xFFFFFFFF);
 233         strncpy((char *)sb.algorithm, params->hash_name, sizeof(sb.algorithm));
 234         memcpy(sb.salt, params->salt, params->salt_size);
 235 #else
 236         sb.version         = cpu_to_le32(1);
 237         sb.hash_type       = cpu_to_le32(params->hash_type);
 238         sb.data_block_size = cpu_to_le64(params->data_block_size);
 239         sb.hash_block_size = cpu_to_le64(params->hash_block_size);
 240         sb.salt_size       = cpu_to_le16(params->salt_size);
 241         sb.data_blocks     = cpu_to_le64(params->data_size);
 242         strncpy((char *)sb.algorithm, params->hash_name, sizeof(sb.algorithm));
 243         memcpy(sb.salt, params->salt, params->salt_size);
 244         memcpy(sb.uuid, uuid, sizeof(sb.uuid));
 245 #endif
 246         r = write_lseek_blockwise(devfd, (char*)&sb, hdr_size, sb_offset) < hdr_size ? -EIO : 0;
 247         if (r)
 248                 log_err(cd, _("Error during update of verity header on device %s.\n"), device);
 249         close(devfd);
 250
 251         return r;
 252 }
 253
 254 /* Calculate hash offset in hash blocks */
 255 uint64_t VERITY_hash_offset_block(struct crypt_params_verity *params)
 256 {
 257         uint64_t hash_offset = params->hash_area_offset;
 258
 259         if (params->flags & CRYPT_VERITY_NO_HEADER)
 260                 return hash_offset / params->hash_block_size;
 261
 262         hash_offset += sizeof(struct verity_sb);
 263         hash_offset += params->hash_block_size - 1;
 264
 265         return hash_offset / params->hash_block_size;
 266 }
 267
 268 int VERITY_UUID_generate(struct crypt_device *cd, char **uuid_string)
 269 {
 270         uuid_t uuid;
 271
 272         if (!(*uuid_string = malloc(40)))
 273                 return -ENOMEM;
 274         uuid_generate(uuid);
 275         uuid_unparse(uuid, *uuid_string);
 276         return 0;
 277 }
 278
 279 /* Activate verity device in kernel device-mapper */
 280 int VERITY_activate(struct crypt_device *cd,
 281                      const char *name,
 282                      const char *hash_device,
 283                      const char *root_hash,
 284                      size_t root_hash_size,
 285                      struct crypt_params_verity *verity_hdr,
 286                      uint32_t activation_flags)
 287 {
 288         struct crypt_dm_active_device dmd;
 289         uint64_t offset = 0;
 290         int r;
 291
 292         log_dbg("Trying to activate VERITY device %s using hash %s.",
 293                 name ?: "[none]", verity_hdr->hash_name);
 294
 295         if (verity_hdr->flags & CRYPT_VERITY_CHECK_HASH) {
 296                 r = VERITY_verify(cd, verity_hdr,
 297                                   crypt_get_device_name(cd), hash_device,
 298                                   root_hash, root_hash_size);
 299                 if (r < 0)
 300                         return r;
 301         }
 302
 303         if (!name)
 304                 return 0;
 305
 306         dmd.target = DM_VERITY;
 307         dmd.data_device = crypt_get_device_name(cd);
 308         dmd.u.verity.hash_device = hash_device;
 309         dmd.u.verity.root_hash = root_hash;
 310         dmd.u.verity.root_hash_size = root_hash_size;
 311         dmd.u.verity.hash_offset = VERITY_hash_offset_block(verity_hdr),
 312         dmd.flags = activation_flags;
 313         dmd.size = verity_hdr->data_size * verity_hdr->data_block_size / 512;
 314         dmd.uuid = crypt_get_uuid(cd);
 315         dmd.u.verity.vp = verity_hdr;
 316
 317         r = device_check_and_adjust(cd, dmd.data_device, DEV_EXCL,
 318                                     &dmd.size, &offset, &dmd.flags);
 319         if (r)
 320                 return r;
 321
 322         r = dm_create_device(name, CRYPT_VERITY, &dmd, 0);
 323         if (!r && !(dm_flags() & DM_VERITY_SUPPORTED)) {
 324                 log_err(cd, _("Kernel doesn't support dm-verity mapping.\n"));
 325                 return -ENOTSUP;
 326         }
 327         if (r < 0)
 328                 return r;
 329
 330         r = dm_status_verity_ok(name);
 331         if (r < 0)
 332                 return r;
 333
 334         if (!r)
 335                 log_err(cd, _("Verity device detected corruption after activation.\n"));
 336         return 0;
 337 }