diff options
Diffstat (limited to 'lib/verity/verity.c')
| -rw-r--r-- | lib/verity/verity.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/lib/verity/verity.c b/lib/verity/verity.c new file mode 100644 index 0000000..278f34a --- /dev/null +++ b/lib/verity/verity.c @@ -0,0 +1,354 @@ +/* + * dm-verity volume handling + * + * Copyright (C) 2012-2021 Red Hat, Inc. All rights reserved. + * + * This file is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This file is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this file; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <stdint.h> +#include <ctype.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <netinet/in.h> +#include <uuid/uuid.h> + +#include "libcryptsetup.h" +#include "verity.h" +#include "internal.h" + +#define VERITY_SIGNATURE "verity\0\0" + +/* https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity#verity-superblock-format */ +struct verity_sb { + uint8_t signature[8]; /* "verity\0\0" */ + uint32_t version; /* superblock version */ + uint32_t hash_type; /* 0 - Chrome OS, 1 - normal */ + uint8_t uuid[16]; /* UUID of hash device */ + uint8_t algorithm[32];/* hash algorithm name */ + uint32_t data_block_size; /* data block in bytes */ + uint32_t hash_block_size; /* hash block in bytes */ + uint64_t data_blocks; /* number of data blocks */ + uint16_t salt_size; /* salt size */ + uint8_t _pad1[6]; + uint8_t salt[256]; /* salt */ + uint8_t _pad2[168]; +} __attribute__((packed)); + +/* Read verity superblock from disk */ +int VERITY_read_sb(struct crypt_device *cd, + uint64_t sb_offset, + char **uuid_string, + struct crypt_params_verity *params) +{ + struct device *device = crypt_metadata_device(cd); + struct verity_sb sb = {}; + ssize_t hdr_size = sizeof(struct verity_sb); + int devfd, sb_version; + + log_dbg(cd, "Reading VERITY header of size %zu on device %s, offset %" PRIu64 ".", + sizeof(struct verity_sb), device_path(device), sb_offset); + + if (params->flags & CRYPT_VERITY_NO_HEADER) { + log_err(cd, _("Verity device %s does not use on-disk header."), + device_path(device)); + return -EINVAL; + } + + if (MISALIGNED_512(sb_offset)) { + log_err(cd, _("Unsupported VERITY hash offset.")); + return -EINVAL; + } + + devfd = device_open(cd, device, O_RDONLY); + if (devfd < 0) { + log_err(cd, _("Cannot open device %s."), device_path(device)); + return -EINVAL; + } + + if (read_lseek_blockwise(devfd, device_block_size(cd, device), + device_alignment(device), &sb, hdr_size, + sb_offset) < hdr_size) + return -EIO; + + if (memcmp(sb.signature, VERITY_SIGNATURE, sizeof(sb.signature))) { + log_err(cd, _("Device %s is not a valid VERITY device."), + device_path(device)); + return -EINVAL; + } + + sb_version = le32_to_cpu(sb.version); + if (sb_version != 1) { + log_err(cd, _("Unsupported VERITY version %d."), sb_version); + return -EINVAL; + } + params->hash_type = le32_to_cpu(sb.hash_type); + if (params->hash_type > VERITY_MAX_HASH_TYPE) { + log_err(cd, _("Unsupported VERITY hash type %d."), params->hash_type); + return -EINVAL; + } + + params->data_block_size = le32_to_cpu(sb.data_block_size); + params->hash_block_size = le32_to_cpu(sb.hash_block_size); + if (VERITY_BLOCK_SIZE_OK(params->data_block_size) || + VERITY_BLOCK_SIZE_OK(params->hash_block_size)) { + log_err(cd, _("Unsupported VERITY block size.")); + return -EINVAL; + } + params->data_size = le64_to_cpu(sb.data_blocks); + + params->hash_name = strndup((const char*)sb.algorithm, sizeof(sb.algorithm)); + if (!params->hash_name) + return -ENOMEM; + if (crypt_hash_size(params->hash_name) <= 0) { + log_err(cd, _("Hash algorithm %s not supported."), + params->hash_name); + free(CONST_CAST(char*)params->hash_name); + params->hash_name = NULL; + return -EINVAL; + } + + params->salt_size = le16_to_cpu(sb.salt_size); + if (params->salt_size > sizeof(sb.salt)) { + log_err(cd, _("VERITY header corrupted.")); + free(CONST_CAST(char*)params->hash_name); + params->hash_name = NULL; + return -EINVAL; + } + params->salt = malloc(params->salt_size); + if (!params->salt) { + free(CONST_CAST(char*)params->hash_name); + params->hash_name = NULL; + return -ENOMEM; + } + memcpy(CONST_CAST(char*)params->salt, sb.salt, params->salt_size); + + if ((*uuid_string = malloc(40))) + uuid_unparse(sb.uuid, *uuid_string); + + params->hash_area_offset = sb_offset; + return 0; +} + +static void _to_lower(char *str) +{ + for(; *str; str++) + if (isupper(*str)) + *str = tolower(*str); +} + +/* Write verity superblock to disk */ +int VERITY_write_sb(struct crypt_device *cd, + uint64_t sb_offset, + const char *uuid_string, + struct crypt_params_verity *params) +{ + struct device *device = crypt_metadata_device(cd); + struct verity_sb sb = {}; + ssize_t hdr_size = sizeof(struct verity_sb); + size_t block_size; + char *algorithm; + uuid_t uuid; + int r, devfd; + + log_dbg(cd, "Updating VERITY header of size %zu on device %s, offset %" PRIu64 ".", + sizeof(struct verity_sb), device_path(device), sb_offset); + + if (!uuid_string || uuid_parse(uuid_string, uuid) == -1) { + log_err(cd, _("Wrong VERITY UUID format provided on device %s."), + device_path(device)); + return -EINVAL; + } + + if (params->flags & CRYPT_VERITY_NO_HEADER) { + log_err(cd, _("Verity device %s does not use on-disk header."), + device_path(device)); + return -EINVAL; + } + + /* Avoid possible increasing of image size - FEC could fail later because of it */ + block_size = device_block_size(cd, device); + if (block_size > params->hash_block_size) { + device_disable_direct_io(device); + block_size = params->hash_block_size; + } + + devfd = device_open(cd, device, O_RDWR); + if (devfd < 0) { + log_err(cd, _("Cannot open device %s."), device_path(device)); + return -EINVAL; + } + + memcpy(&sb.signature, VERITY_SIGNATURE, sizeof(sb.signature)); + sb.version = cpu_to_le32(1); + sb.hash_type = cpu_to_le32(params->hash_type); + sb.data_block_size = cpu_to_le32(params->data_block_size); + sb.hash_block_size = cpu_to_le32(params->hash_block_size); + sb.salt_size = cpu_to_le16(params->salt_size); + sb.data_blocks = cpu_to_le64(params->data_size); + + /* Kernel always use lower-case */ + algorithm = (char *)sb.algorithm; + strncpy(algorithm, params->hash_name, sizeof(sb.algorithm)-1); + algorithm[sizeof(sb.algorithm)-1] = '\0'; + _to_lower(algorithm); + + memcpy(sb.salt, params->salt, params->salt_size); + memcpy(sb.uuid, uuid, sizeof(sb.uuid)); + + r = write_lseek_blockwise(devfd, block_size, device_alignment(device), + (char*)&sb, hdr_size, sb_offset) < hdr_size ? -EIO : 0; + if (r) + log_err(cd, _("Error during update of verity header on device %s."), + device_path(device)); + + device_sync(cd, device); + + return r; +} + +/* Calculate hash offset in hash blocks */ +uint64_t VERITY_hash_offset_block(struct crypt_params_verity *params) +{ + uint64_t hash_offset = params->hash_area_offset; + + if (params->flags & CRYPT_VERITY_NO_HEADER) + return hash_offset / params->hash_block_size; + + hash_offset += sizeof(struct verity_sb); + hash_offset += params->hash_block_size - 1; + + return hash_offset / params->hash_block_size; +} + +int VERITY_UUID_generate(struct crypt_device *cd, char **uuid_string) +{ + uuid_t uuid; + + *uuid_string = malloc(40); + if (!*uuid_string) + return -ENOMEM; + uuid_generate(uuid); + uuid_unparse(uuid, *uuid_string); + return 0; +} + +/* Activate verity device in kernel device-mapper */ +int VERITY_activate(struct crypt_device *cd, + const char *name, + const char *root_hash, + size_t root_hash_size, + const char *signature_description, + struct device *fec_device, + struct crypt_params_verity *verity_hdr, + uint32_t activation_flags) +{ + uint32_t dmv_flags; + unsigned int fec_errors = 0; + int r, v; + struct crypt_dm_active_device dmd = { + .size = verity_hdr->data_size * verity_hdr->data_block_size / 512, + .flags = activation_flags, + .uuid = crypt_get_uuid(cd), + }; + + log_dbg(cd, "Trying to activate VERITY device %s using hash %s.", + name ?: "[none]", verity_hdr->hash_name); + + if (verity_hdr->flags & CRYPT_VERITY_CHECK_HASH) { + if (signature_description) { + log_err(cd, _("Root hash signature verification is not supported.")); + return -EINVAL; + } + + log_dbg(cd, "Verification of data in userspace required."); + r = VERITY_verify(cd, verity_hdr, root_hash, root_hash_size); + + if ((r == -EPERM || r == -EFAULT) && fec_device) { + v = r; + log_dbg(cd, "Verification failed, trying to repair with FEC device."); + r = VERITY_FEC_process(cd, verity_hdr, fec_device, 1, &fec_errors); + if (r < 0) + log_err(cd, _("Errors cannot be repaired with FEC device.")); + else if (fec_errors) { + log_err(cd, _("Found %u repairable errors with FEC device."), + fec_errors); + /* If root hash failed, we cannot be sure it was properly repaired */ + } + if (v == -EFAULT) + r = -EPERM; + } + + if (r < 0) + return r; + } + + if (!name) + return 0; + + r = device_block_adjust(cd, crypt_metadata_device(cd), DEV_OK, + 0, NULL, NULL); + if (r) + return r; + + r = device_block_adjust(cd, crypt_data_device(cd), DEV_EXCL, + 0, &dmd.size, &dmd.flags); + if (r) + return r; + + if (fec_device) { + r = device_block_adjust(cd, fec_device, DEV_OK, + 0, NULL, NULL); + if (r) + return r; + } + + r = dm_verity_target_set(&dmd.segment, 0, dmd.size, crypt_data_device(cd), + crypt_metadata_device(cd), fec_device, root_hash, + root_hash_size, signature_description, + VERITY_hash_offset_block(verity_hdr), + VERITY_FEC_blocks(cd, fec_device, verity_hdr), verity_hdr); + + if (r) + return r; + + r = dm_create_device(cd, name, CRYPT_VERITY, &dmd); + if (r < 0 && (dm_flags(cd, DM_VERITY, &dmv_flags) || !(dmv_flags & DM_VERITY_SUPPORTED))) { + log_err(cd, _("Kernel does not support dm-verity mapping.")); + r = -ENOTSUP; + } + if (r < 0 && signature_description && !(dmv_flags & DM_VERITY_SIGNATURE_SUPPORTED)) { + log_err(cd, _("Kernel does not support dm-verity signature option.")); + r = -ENOTSUP; + } + if (r < 0) + goto out; + + r = dm_status_verity_ok(cd, name); + if (r < 0) + goto out; + + if (!r) + log_err(cd, _("Verity device detected corruption after activation.")); + + r = 0; +out: + dm_targets_free(cd, &dmd); + return r; +} |