- 根目录:
- drivers
- md
- dm-android-verity.c
/*
* Copyright (C) 2015 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program 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 General Public License for more details.
*
*/
#include <linux/buffer_head.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/device-mapper.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/key.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/of.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <asm/setup.h>
#include <crypto/hash.h>
#include <crypto/public_key.h>
#include <crypto/sha.h>
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include "dm-verity.h"
#include "dm-android-verity.h"
static char verifiedbootstate[VERITY_COMMANDLINE_PARAM_LENGTH];
static char veritymode[VERITY_COMMANDLINE_PARAM_LENGTH];
static int __init verified_boot_state_param(char *line)
{
strlcpy(verifiedbootstate, line, sizeof(verifiedbootstate));
return 1;
}
__setup("androidboot.verifiedbootstate=", verified_boot_state_param);
static int __init verity_mode_param(char *line)
{
strlcpy(veritymode, line, sizeof(veritymode));
return 1;
}
__setup("androidboot.veritymode=", verity_mode_param);
static int table_extract_mpi_array(struct public_key_signature *pks,
const void *data, size_t len)
{
MPI mpi = mpi_read_raw_data(data, len);
if (!mpi) {
DMERR("Error while allocating mpi array");
return -ENOMEM;
}
pks->mpi[0] = mpi;
pks->nr_mpi = 1;
return 0;
}
static struct public_key_signature *table_make_digest(
enum hash_algo hash,
const void *table,
unsigned long table_len)
{
struct public_key_signature *pks = NULL;
struct crypto_shash *tfm;
struct shash_desc *desc;
size_t digest_size, desc_size;
int ret;
/* Allocate the hashing algorithm we're going to need and find out how
* big the hash operational data will be.
*/
tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0);
if (IS_ERR(tfm))
return ERR_CAST(tfm);
desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
digest_size = crypto_shash_digestsize(tfm);
/* We allocate the hash operational data storage on the end of out
* context data and the digest output buffer on the end of that.
*/
ret = -ENOMEM;
pks = kzalloc(digest_size + sizeof(*pks) + desc_size, GFP_KERNEL);
if (!pks)
goto error;
pks->pkey_hash_algo = hash;
pks->digest = (u8 *)pks + sizeof(*pks) + desc_size;
pks->digest_size = digest_size;
desc = (struct shash_desc *)(pks + 1);
desc->tfm = tfm;
desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
ret = crypto_shash_init(desc);
if (ret < 0)
goto error;
ret = crypto_shash_finup(desc, table, table_len, pks->digest);
if (ret < 0)
goto error;
crypto_free_shash(tfm);
return pks;
error:
kfree(pks);
crypto_free_shash(tfm);
return ERR_PTR(ret);
}
static int read_block_dev(struct bio_read *payload, struct block_device *bdev,
sector_t offset, int length)
{
struct bio *bio;
int err = 0, i;
payload->number_of_pages = DIV_ROUND_UP(length, PAGE_SIZE);
bio = bio_alloc(GFP_KERNEL, payload->number_of_pages);
if (!bio) {
DMERR("Error while allocating bio");
return -ENOMEM;
}
bio->bi_bdev = bdev;
bio->bi_iter.bi_sector = offset;
payload->page_io = kzalloc(sizeof(struct page *) *
payload->number_of_pages, GFP_KERNEL);
if (!payload->page_io) {
DMERR("page_io array alloc failed");
err = -ENOMEM;
goto free_bio;
}
for (i = 0; i < payload->number_of_pages; i++) {
payload->page_io[i] = alloc_page(GFP_KERNEL);
if (!payload->page_io[i]) {
DMERR("alloc_page failed");
err = -ENOMEM;
goto free_pages;
}
if (!bio_add_page(bio, payload->page_io[i], PAGE_SIZE, 0)) {
DMERR("bio_add_page error");
err = -EIO;
goto free_pages;
}
}
if (!submit_bio_wait(READ, bio))
/* success */
goto free_bio;
DMERR("bio read failed");
err = -EIO;
free_pages:
for (i = 0; i < payload->number_of_pages; i++)
if (payload->page_io[i])
__free_page(payload->page_io[i]);
kfree(payload->page_io);
free_bio:
bio_put(bio);
return err;
}
static inline u64 fec_div_round_up(u64 x, u64 y)
{
u64 remainder;
return div64_u64_rem(x, y, &remainder) +
(remainder > 0 ? 1 : 0);
}
static inline void populate_fec_metadata(struct fec_header *header,
struct fec_ecc_metadata *ecc)
{
ecc->blocks = fec_div_round_up(le64_to_cpu(header->inp_size),
FEC_BLOCK_SIZE);
ecc->roots = le32_to_cpu(header->roots);
ecc->start = le64_to_cpu(header->inp_size);
}
static inline int validate_fec_header(struct fec_header *header, u64 offset)
{
/* move offset to make the sanity check work for backup header
* as well. */
offset -= offset % FEC_BLOCK_SIZE;
if (le32_to_cpu(header->magic) != FEC_MAGIC ||
le32_to_cpu(header->version) != FEC_VERSION ||
le32_to_cpu(header->size) != sizeof(struct fec_header) ||
le32_to_cpu(header->roots) == 0 ||
le32_to_cpu(header->roots) >= FEC_RSM ||
offset < le32_to_cpu(header->fec_size) ||
offset - le32_to_cpu(header->fec_size) !=
le64_to_cpu(header->inp_size))
return -EINVAL;
return 0;
}
static int extract_fec_header(dev_t dev, struct fec_header *fec,
struct fec_ecc_metadata *ecc)
{
u64 device_size;
struct bio_read payload;
int i, err = 0;
struct block_device *bdev;
bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
if (IS_ERR(bdev)) {
DMERR("bdev get error");
return PTR_ERR(bdev);
}
device_size = i_size_read(bdev->bd_inode);
/* fec metadata size is a power of 2 and PAGE_SIZE
* is a power of 2 as well.
*/
BUG_ON(FEC_BLOCK_SIZE > PAGE_SIZE);
/* 512 byte sector alignment */
BUG_ON(((device_size - FEC_BLOCK_SIZE) % (1 << SECTOR_SHIFT)) != 0);
err = read_block_dev(&payload, bdev, (device_size -
FEC_BLOCK_SIZE) / (1 << SECTOR_SHIFT), FEC_BLOCK_SIZE);
if (err) {
DMERR("Error while reading verity metadata");
goto error;
}
BUG_ON(sizeof(struct fec_header) > PAGE_SIZE);
memcpy(fec, page_address(payload.page_io[0]),
sizeof(*fec));
ecc->valid = true;
if (validate_fec_header(fec, device_size - FEC_BLOCK_SIZE)) {
/* Try the backup header */
memcpy(fec, page_address(payload.page_io[0]) + FEC_BLOCK_SIZE
- sizeof(*fec) ,
sizeof(*fec));
if (validate_fec_header(fec, device_size -
sizeof(struct fec_header)))
ecc->valid = false;
}
if (ecc->valid)
populate_fec_metadata(fec, ecc);
for (i = 0; i < payload.number_of_pages; i++)
__free_page(payload.page_io[i]);
kfree(payload.page_io);
error:
blkdev_put(bdev, FMODE_READ);
return err;
}
static void find_metadata_offset(struct fec_header *fec,
struct block_device *bdev, u64 *metadata_offset)
{
u64 device_size;
device_size = i_size_read(bdev->bd_inode);
if (le32_to_cpu(fec->magic) == FEC_MAGIC)
*metadata_offset = le64_to_cpu(fec->inp_size) -
VERITY_METADATA_SIZE;
else
*metadata_offset = device_size - VERITY_METADATA_SIZE;
}
static struct android_metadata *extract_metadata(dev_t dev,
struct fec_header *fec)
{
struct block_device *bdev;
struct android_metadata_header *header;
struct android_metadata *uninitialized_var(metadata);
int i;
u32 table_length, copy_length, offset;
u64 metadata_offset;
struct bio_read payload;
int err = 0;
bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
if (IS_ERR(bdev)) {
DMERR("blkdev_get_by_dev failed");
return ERR_CAST(bdev);
}
find_metadata_offset(fec, bdev, &metadata_offset);
/* Verity metadata size is a power of 2 and PAGE_SIZE
* is a power of 2 as well.
* PAGE_SIZE is also a multiple of 512 bytes.
*/
if (VERITY_METADATA_SIZE > PAGE_SIZE)
BUG_ON(VERITY_METADATA_SIZE % PAGE_SIZE != 0);
/* 512 byte sector alignment */
BUG_ON(metadata_offset % (1 << SECTOR_SHIFT) != 0);
err = read_block_dev(&payload, bdev, metadata_offset /
(1 << SECTOR_SHIFT), VERITY_METADATA_SIZE);
if (err) {
DMERR("Error while reading verity metadata");
metadata = ERR_PTR(err);
goto blkdev_release;
}
header = kzalloc(sizeof(*header), GFP_KERNEL);
if (!header) {
DMERR("kzalloc failed for header");
err = -ENOMEM;
goto free_payload;
}
memcpy(header, page_address(payload.page_io[0]),
sizeof(*header));
DMINFO("bio magic_number:%u protocol_version:%d table_length:%u",
le32_to_cpu(header->magic_number),
le32_to_cpu(header->protocol_version),
le32_to_cpu(header->table_length));
metadata = kzalloc(sizeof(*metadata), GFP_KERNEL);
if (!metadata) {
DMERR("kzalloc for metadata failed");
err = -ENOMEM;
goto free_header;
}
metadata->header = header;
table_length = le32_to_cpu(header->table_length);
if (table_length == 0 ||
table_length > (VERITY_METADATA_SIZE -
sizeof(struct android_metadata_header)))
goto free_metadata;
metadata->verity_table = kzalloc(table_length + 1, GFP_KERNEL);
if (!metadata->verity_table) {
DMERR("kzalloc verity_table failed");
err = -ENOMEM;
goto free_metadata;
}
if (sizeof(struct android_metadata_header) +
table_length <= PAGE_SIZE) {
memcpy(metadata->verity_table, page_address(payload.page_io[0])
+ sizeof(struct android_metadata_header),
table_length);
} else {
copy_length = PAGE_SIZE -
sizeof(struct android_metadata_header);
memcpy(metadata->verity_table, page_address(payload.page_io[0])
+ sizeof(struct android_metadata_header),
copy_length);
table_length -= copy_length;
offset = copy_length;
i = 1;
while (table_length != 0) {
if (table_length > PAGE_SIZE) {
memcpy(metadata->verity_table + offset,
page_address(payload.page_io[i]),
PAGE_SIZE);
offset += PAGE_SIZE;
table_length -= PAGE_SIZE;
} else {
memcpy(metadata->verity_table + offset,
page_address(payload.page_io[i]),
table_length);
table_length = 0;
}
i++;
}
}
metadata->verity_table[table_length] = '\0';
goto free_payload;
free_metadata:
kfree(metadata);
free_header:
kfree(header);
metadata = ERR_PTR(err);
free_payload:
for (i = 0; i < payload.number_of_pages; i++)
if (payload.page_io[i])
__free_page(payload.page_io[i]);
kfree(payload.page_io);
DMINFO("verity_table: %s", metadata->verity_table);
blkdev_release:
blkdev_put(bdev, FMODE_READ);
return metadata;
}
/* helper functions to extract properties from dts */
const char *find_dt_value(const char *name)
{
struct device_node *firmware;
const char *value;
firmware = of_find_node_by_path("/firmware/android");
if (!firmware)
return NULL;
value = of_get_property(firmware, name, NULL);
of_node_put(firmware);
return value;
}
static bool is_unlocked(void)
{
static const char unlocked[] = "orange";
static const char verified_boot_prop[] = "verifiedbootstate";
const char *value;
value = find_dt_value(verified_boot_prop);
if (!value)
value = verifiedbootstate;
return !strncmp(value, unlocked, sizeof(unlocked) - 1);
}
static int verity_mode(void)
{
static const char enforcing[] = "enforcing";
static const char verified_mode_prop[] = "veritymode";
const char *value;
value = find_dt_value(verified_mode_prop);
if (!value)
value = veritymode;
if (!strncmp(value, enforcing, sizeof(enforcing) - 1))
return DM_VERITY_MODE_RESTART;
return DM_VERITY_MODE_EIO;
}
static int verify_header(struct android_metadata_header *header)
{
int retval = -EINVAL;
if (is_unlocked() && le32_to_cpu(header->magic_number) ==
VERITY_METADATA_MAGIC_DISABLE) {
retval = VERITY_STATE_DISABLE;
return retval;
}
if (!(le32_to_cpu(header->magic_number) ==
VERITY_METADATA_MAGIC_NUMBER) ||
(le32_to_cpu(header->magic_number) ==
VERITY_METADATA_MAGIC_DISABLE)) {
DMERR("Incorrect magic number");
return retval;
}
if (le32_to_cpu(header->protocol_version) !=
VERITY_METADATA_VERSION) {
DMERR("Unsupported version %u",
le32_to_cpu(header->protocol_version));
return retval;
}
return 0;
}
static int verify_verity_signature(char *key_id,
struct android_metadata *metadata)
{
key_ref_t key_ref;
struct key *key;
struct public_key_signature *pks = NULL;
int retval = -EINVAL;
key_ref = keyring_search(make_key_ref(system_trusted_keyring, 1),
&key_type_asymmetric, key_id);
if (IS_ERR(key_ref)) {
DMERR("keyring: key not found");
return -ENOKEY;
}
key = key_ref_to_ptr(key_ref);
pks = table_make_digest(HASH_ALGO_SHA256,
(const void *)metadata->verity_table,
le32_to_cpu(metadata->header->table_length));
if (IS_ERR(pks)) {
DMERR("hashing failed");
goto error;
}
retval = table_extract_mpi_array(pks, &metadata->header->signature[0],
RSANUMBYTES);
if (retval < 0) {
DMERR("Error extracting mpi %d", retval);
goto error;
}
retval = verify_signature(key, pks);
mpi_free(pks->rsa.s);
error:
kfree(pks);
key_put(key);
return retval;
}
static void handle_error(void)
{
int mode = verity_mode();
if (mode == DM_VERITY_MODE_RESTART) {
DMERR("triggering restart");
kernel_restart("dm-verity device corrupted");
} else {
DMERR("Mounting verity root failed");
}
}
static inline bool test_mult_overflow(sector_t a, u32 b)
{
sector_t r = (sector_t)~0ULL;
sector_div(r, b);
return a > r;
}
/*
* Target parameters:
* <key id> Key id of the public key in the system keyring.
* Verity metadata's signature would be verified against
* this. If the key id contains spaces, replace them
* with '#'.
* <block device> The block device for which dm-verity is being setup.
*/
static int android_verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
dev_t uninitialized_var(dev);
struct android_metadata *uninitialized_var(metadata);
int err = 0, i, mode;
char *key_id, *table_ptr, dummy,
*verity_table_args[VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS];
/* One for specifying number of opt args and one for mode */
sector_t data_sectors;
u32 data_block_size;
unsigned int major, minor,
no_of_args = VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS;
struct fec_header uninitialized_var(fec);
struct fec_ecc_metadata uninitialized_var(ecc);
char buf[FEC_ARG_LENGTH], *buf_ptr;
unsigned long long tmpll;
if (argc != 2) {
DMERR("Incorrect number of arguments");
handle_error();
return -EINVAL;
}
/* should come as one of the arguments for the verity target */
key_id = argv[0];
strreplace(argv[0], '#', ' ');
if (sscanf(argv[1], "%u:%u%c", &major, &minor, &dummy) == 2) {
dev = MKDEV(major, minor);
if (MAJOR(dev) != major || MINOR(dev) != minor) {
DMERR("Incorrect bdev major minor number");
handle_error();
return -EOVERFLOW;
}
}
DMINFO("key:%s dev:%s", argv[0], argv[1]);
if (extract_fec_header(dev, &fec, &ecc)) {
DMERR("Error while extracting fec header");
handle_error();
return -EINVAL;
}
metadata = extract_metadata(dev, &fec);
if (IS_ERR(metadata)) {
DMERR("Error while extracting metadata");
handle_error();
return -EINVAL;
}
err = verify_header(metadata->header);
if (err == VERITY_STATE_DISABLE) {
DMERR("Mounting root with verity disabled");
return -EINVAL;
} else if (err) {
DMERR("Verity header handle error");
handle_error();
goto free_metadata;
}
err = verify_verity_signature(key_id, metadata);
if (err) {
DMERR("Signature verification failed");
handle_error();
goto free_metadata;
} else
DMINFO("Signature verification success");
table_ptr = metadata->verity_table;
for (i = 0; i < VERITY_TABLE_ARGS; i++) {
verity_table_args[i] = strsep(&table_ptr, " ");
if (verity_table_args[i] == NULL)
break;
}
if (i != VERITY_TABLE_ARGS) {
DMERR("Verity table not in the expected format");
err = -EINVAL;
handle_error();
goto free_metadata;
}
if (sscanf(verity_table_args[5], "%llu%c", &tmpll, &dummy)
!= 1) {
DMERR("Verity table not in the expected format");
handle_error();
err = -EINVAL;
goto free_metadata;
}
if (tmpll > ULONG_MAX) {
DMERR("<num_data_blocks> too large. Forgot to turn on CONFIG_LBDAF?");
handle_error();
err = -EINVAL;
goto free_metadata;
}
data_sectors = tmpll;
if (sscanf(verity_table_args[3], "%u%c", &data_block_size, &dummy)
!= 1) {
DMERR("Verity table not in the expected format");
handle_error();
err = -EINVAL;
goto free_metadata;
}
if (test_mult_overflow(data_sectors, data_block_size >>
SECTOR_SHIFT)) {
DMERR("data_sectors too large");
handle_error();
err = -EOVERFLOW;
goto free_metadata;
}
data_sectors *= data_block_size >> SECTOR_SHIFT;
DMINFO("Data sectors %llu", (unsigned long long)data_sectors);
/* update target length */
ti->len = data_sectors;
/*substitute data_dev and hash_dev*/
verity_table_args[1] = argv[1];
verity_table_args[2] = argv[1];
mode = verity_mode();
if (ecc.valid && IS_BUILTIN(CONFIG_DM_VERITY_FEC)) {
if (mode) {
err = snprintf(buf, FEC_ARG_LENGTH,
"%u %s " VERITY_TABLE_OPT_FEC_FORMAT,
1 + VERITY_TABLE_OPT_FEC_ARGS,
mode == DM_VERITY_MODE_RESTART ?
VERITY_TABLE_OPT_RESTART : VERITY_TABLE_OPT_LOGGING,
argv[1], ecc.start / FEC_BLOCK_SIZE, ecc.blocks,
ecc.roots);
} else {
err = snprintf(buf, FEC_ARG_LENGTH,
"%u " VERITY_TABLE_OPT_FEC_FORMAT,
VERITY_TABLE_OPT_FEC_ARGS, argv[1],
ecc.start / FEC_BLOCK_SIZE, ecc.blocks, ecc.roots);
}
} else if (mode) {
err = snprintf(buf, FEC_ARG_LENGTH,
"2 " VERITY_TABLE_OPT_IGNZERO " %s",
mode == DM_VERITY_MODE_RESTART ?
VERITY_TABLE_OPT_RESTART : VERITY_TABLE_OPT_LOGGING);
} else {
err = snprintf(buf, FEC_ARG_LENGTH, "1 %s",
"ignore_zero_blocks");
}
if (err < 0 || err >= FEC_ARG_LENGTH)
goto free_metadata;
buf_ptr = buf;
for (i = VERITY_TABLE_ARGS; i < (VERITY_TABLE_ARGS +
VERITY_TABLE_OPT_FEC_ARGS + 2); i++) {
verity_table_args[i] = strsep(&buf_ptr, " ");
if (verity_table_args[i] == NULL) {
no_of_args = i;
break;
}
}
err = verity_ctr(ti, no_of_args, verity_table_args);
free_metadata:
kfree(metadata->header);
kfree(metadata->verity_table);
kfree(metadata);
return err;
}
static struct target_type android_verity_target = {
.name = "android-verity",
.version = {1, 0, 0},
.module = THIS_MODULE,
.ctr = android_verity_ctr,
.dtr = verity_dtr,
.map = verity_map,
.status = verity_status,
.ioctl = verity_ioctl,
.merge = verity_merge,
.iterate_devices = verity_iterate_devices,
.io_hints = verity_io_hints,
};
static int __init dm_android_verity_init(void)
{
int r;
r = dm_register_target(&android_verity_target);
if (r < 0)
DMERR("register failed %d", r);
return r;
}
static void __exit dm_android_verity_exit(void)
{
dm_unregister_target(&android_verity_target);
}
module_init(dm_android_verity_init);
module_exit(dm_android_verity_exit);