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