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feat(core/sdbackup): improve recovery

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- recovery does not need filesystem
- so far not possible to use SD with shamir
- export first backup block as a C constant
- WIP
This commit is contained in:
obrusvit 2023-12-06 11:20:27 +01:00
parent 83b4066f55
commit 9df4b5e24f
12 changed files with 166 additions and 82 deletions
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25
core/embed/extmod/modtrezorio/modtrezorio-fatfs.h
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@ -21,6 +21,7 @@
#include "py/mperrno.h"
#include "py/obj.h"
#include "py/objstr.h"
#include "stdio.h"
// clang-format off
#include "ff.h"
@ -559,10 +560,10 @@ STATIC mp_obj_t mod_trezorio_fatfs_mkfs(size_t n_args, const mp_obj_t *args) {
// create partition
if (n_args > 0 && args[0] == mp_const_true) {
// for SD card backup: we make a small partition and keep the rest
// unallocated
// TODO: seems like not big enough for Windows (problem detected popup)
const int n_clusters = 0xFFF5 + 1 + 549; // MAX_FAT16 + 1 + overhead
// for SD card backup: we make a small FAT32 partition and keep the rest
// unallocated, FatFS allows smallest size as 0xFFF5 + 550. Windows needs
// two more clusters not to complain. MAX_FAT16 + 1 + 551
const int n_clusters = 0xFFF5 + 552;
make_partition(n_clusters);
} else {
// for other use (SD salt): make the partition over the whole space.
@ -589,14 +590,14 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorio_fatfs_mkfs_obj, 0, 1,
/// """
STATIC mp_obj_t mod_trezorio_fatfs_get_capacity() {
FATFS_ONLY_MOUNTED;
/* printf("csize: %d\n", fs_instance.csize); */
/* printf("fatent: %d\n", fs_instance.n_fatent); */
/* printf("free clusters: %d\n", fs_instance.free_clst); */
/* printf("volbase: %d\n", fs_instance.volbase); */
/* printf("fatbase: %d\n", fs_instance.fatbase); */
/* printf("dirbase: %d\n", fs_instance.dirbase); */
/* printf("database: %d\n", fs_instance.database); */
/* printf("winsect: %d\n", fs_instance.winsect); */
printf("csize: %d\n", fs_instance.csize);
printf("fatent: %d\n", fs_instance.n_fatent);
printf("free clusters: %d\n", fs_instance.free_clst);
printf("volbase: %d\n", fs_instance.volbase);
printf("fatbase: %d\n", fs_instance.fatbase);
printf("dirbase: %d\n", fs_instance.dirbase);
printf("database: %d\n", fs_instance.database);
printf("winsect: %d\n", fs_instance.winsect);
// total number of clusters in the filesystem
DWORD total_clusters = fs_instance.n_fatent - 2;
// size of each cluster in bytes

6
core/embed/extmod/modtrezorio/modtrezorio-sdcard.h
View File

@ -25,6 +25,7 @@
/// package: trezorio.sdcard
/// BLOCK_SIZE: int # size of SD card block
/// BACKUP_BLOCK_START: int # first sector for SD seed backup
/// def is_present() -> bool:
/// """
@ -78,7 +79,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_trezorio_sdcard_capacity_obj,
/// """
/// Reads blocks starting with block_num from the SD card into buf.
/// Number of bytes read is length of buf rounded down to multiply of
/// SDCARD_BLOCK_SIZE.
/// SDCARD_BLOCK_SIZE.
/// """
STATIC mp_obj_t mod_trezorio_sdcard_read(mp_obj_t block_num, mp_obj_t buf) {
uint32_t block = trezor_obj_get_uint(block_num);
@ -97,7 +98,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorio_sdcard_read_obj,
/// """
/// Writes blocks starting with block_num from buf to the SD card.
/// Number of bytes written is length of buf rounded down to multiply of
/// SDCARD_BLOCK_SIZE.
/// SDCARD_BLOCK_SIZE.
/// """
STATIC mp_obj_t mod_trezorio_sdcard_write(mp_obj_t block_num, mp_obj_t buf) {
uint32_t block = trezor_obj_get_uint(block_num);
@ -124,6 +125,7 @@ STATIC const mp_rom_map_elem_t mod_trezorio_sdcard_globals_table[] = {
{MP_ROM_QSTR(MP_QSTR_capacity),
MP_ROM_PTR(&mod_trezorio_sdcard_capacity_obj)},
{MP_ROM_QSTR(MP_QSTR_BLOCK_SIZE), MP_ROM_INT(SDCARD_BLOCK_SIZE)},
{MP_ROM_QSTR(MP_QSTR_BACKUP_BLOCK_START), MP_ROM_INT(SDCARD_BACKUP_BLOCK_START)},
{MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mod_trezorio_sdcard_read_obj)},
{MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mod_trezorio_sdcard_write_obj)},
};

3
core/embed/trezorhal/sdcard.h
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@ -50,6 +50,9 @@
// this is a fixed size and should not be changed
#define SDCARD_BLOCK_SIZE (512)
// fixed offset for SD seed backup:
// Maximal size for FAT16 + overhead + start offset (65525 + 552 + 63)
#define SDCARD_BACKUP_BLOCK_START (66140)
void sdcard_init(void);
secbool __wur sdcard_power_on(void);

5
core/mocks/generated/trezorio/sdcard.pyi
View File

@ -1,5 +1,6 @@
from typing import *
BLOCK_SIZE: int # size of SD card block
BACKUP_BLOCK_START: int # first sector for SD seed backup
# extmod/modtrezorio/modtrezorio-sdcard.h
@ -37,7 +38,7 @@ def read(block_num: int, buf: bytearray) -> None:
"""
Reads blocks starting with block_num from the SD card into buf.
Number of bytes read is length of buf rounded down to multiply of
SDCARD_BLOCK_SIZE.
SDCARD_BLOCK_SIZE.
"""
@ -46,5 +47,5 @@ def write(block_num: int, buf: bytes) -> None:
"""
Writes blocks starting with block_num from buf to the SD card.
Number of bytes written is length of buf rounded down to multiply of
SDCARD_BLOCK_SIZE.
SDCARD_BLOCK_SIZE.
"""

1
core/src/apps/management/recovery_device/__init__.py
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@ -24,7 +24,6 @@ async def recovery_device(msg: RecoveryDevice) -> Success:
from trezor.ui.layouts import (
confirm_action,
confirm_reset_device,
choose_backup_medium,
)
from apps.common.request_pin import (

89
core/src/apps/management/recovery_device/homescreen.py
View File

@ -41,39 +41,57 @@ async def recovery_process() -> Success:
raise wire.ActionCancelled
async def _choose_backup_medium() -> str:
from trezor import utils
if utils.USE_SD_CARD:
from apps.management.sd_backup import bip39_choose_backup_medium
# ask the user for backup type (words/SD card)
backup_medium: str = await bip39_choose_backup_medium(recovery=True)
else:
backup_medium: str = "words"
return backup_medium
async def _continue_recovery_process() -> Success:
from trezor import utils
from trezor.errors import MnemonicError
from trezor.ui.layouts import choose_backup_medium
if utils.USE_SD_CARD:
from apps.management.sd_backup import (
sdcard_recover_seed,
)
# gather the current recovery state from storage
dry_run = storage_recovery.is_dry_run()
word_count, backup_type = recover.load_slip39_state()
# ask the user for backup type (words/SD card)
backup_medium: str = await choose_backup_medium(recovery=True)
if backup_medium == "sdcard":
from apps.management.sd_backup import sdcard_recover_seed
# Both word_count and backup_type are derived from the same data. Both will be
# either set or unset. We use 'backup_type is None' to detect status of both.
# The following variable indicates that we are (re)starting the first recovery step,
# which includes word count selection.
is_first_step = backup_type is None
words = await sdcard_recover_seed()
if not words:
raise wire.ProcessError("SD card backup could not be recovered.")
secret, backup_type = await _process_words(words)
else:
# Both word_count and backup_type are derived from the same data. Both will be
# either set or unset. We use 'backup_type is None' to detect status of both.
# The following variable indicates that we are (re)starting the first recovery step,
# which includes word count selection.
is_first_step = backup_type is None
if not is_first_step:
assert word_count is not None
# If we continue recovery, show starting screen with word count immediately.
await _request_share_first_screen(word_count)
if not is_first_step:
assert word_count is not None
# If we continue recovery, show starting screen with word count immediately.
await _request_share_first_screen(word_count)
secret = None
while secret is None:
if is_first_step:
secret = None
while secret is None:
if is_first_step:
backup_medium: str = await _choose_backup_medium()
if backup_medium == "sdcard":
# attempt to recover words from sd card
words = await sdcard_recover_seed()
if words is None:
continue
word_count = len(words.split())
if word_count not in (12, 24):
await show_warning("Shamir not yet supported for SD")
raise wire.ProcessError("Attempt to recover Shamir from SD card.")
else:
# If we are starting recovery, ask for word count first...
# _request_word_count
# For TT, just continuing straight to word count keyboard
@ -85,23 +103,24 @@ async def _continue_recovery_process() -> Success:
word_count = await layout.request_word_count(dry_run)
# ...and only then show the starting screen with word count.
await _request_share_first_screen(word_count)
assert word_count is not None
assert word_count is not None
if backup_medium == "words":
# ask for mnemonic words one by one
words = await layout.request_mnemonic(word_count, backup_type)
# if they were invalid or some checks failed we continue and request them again
if not words:
continue
# if they were invalid or some checks failed we continue and request them again
if not words:
continue
try:
secret, backup_type = await _process_words(words)
# If _process_words succeeded, we now have both backup_type (from
# its result) and word_count (from _request_word_count earlier), which means
# that the first step is complete.
is_first_step = False
except MnemonicError:
await layout.show_invalid_mnemonic(word_count)
try:
secret, backup_type = await _process_words(words)
# If _process_words succeeded, we now have both backup_type (from
# its result) and word_count (from _request_word_count earlier), which means
# that the first step is complete.
is_first_step = False
except MnemonicError:
await layout.show_invalid_mnemonic(word_count)
assert backup_type is not None
if dry_run:

10
core/src/apps/management/reset_device/__init__.py
View File

@ -215,18 +215,26 @@ def _compute_secret_from_entropy(
async def _backup_bip39_sdcard(mnemonic: str) -> None:
from apps.management.sd_backup import sdcard_backup_seed
backup_success: bool = await sdcard_backup_seed(mnemonic)
if not backup_success:
raise ProcessError("SD Card backup could not be verified.")
async def backup_seed(backup_type: BackupType, mnemonic_secret: bytes) -> None:
from trezor import utils
if backup_type == BAK_T_SLIP39_BASIC:
await _backup_slip39_basic(mnemonic_secret)
elif backup_type == BAK_T_SLIP39_ADVANCED:
await _backup_slip39_advanced(mnemonic_secret)
else:
backup_medium: str = await layout.bip39_choose_backup_medium()
if utils.USE_SD_CARD:
from apps.management.sd_backup import bip39_choose_backup_medium
backup_medium: str = await bip39_choose_backup_medium()
else:
backup_medium: str = "words"
if backup_medium == "sdcard":
await _backup_bip39_sdcard(mnemonic_secret)
elif backup_medium == "words":

6
core/src/apps/management/reset_device/layout.py
View File

@ -158,12 +158,6 @@ async def show_backup_success() -> None:
# BIP39
# ===
async def bip39_choose_backup_medium() -> str:
# TODO this will be general, not only for BIP39
from trezor.ui.layouts import choose_backup_medium
return await choose_backup_medium()
async def bip39_show_and_confirm_mnemonic(mnemonic: str) -> None:
# warn user about mnemonic safety

6
core/src/apps/management/sd_backup.py
View File

@ -5,6 +5,12 @@ from storage.sd_seed_backup import store_seed_on_sdcard, recover_seed_from_sdcar
if utils.USE_SD_CARD:
fatfs = io.fatfs # global_import_cache
async def bip39_choose_backup_medium(recovery: bool = False) -> str:
# TODO this will be general, not only for BIP39
from trezor.ui.layouts import choose_backup_medium
return await choose_backup_medium(recovery)
async def sdcard_backup_seed(mnemonic_secret: bytes) -> bool:
from apps.common.sdcard import ensure_sdcard

46
core/src/storage/sd_seed_backup.py
View File

@ -3,20 +3,19 @@ from typing import TYPE_CHECKING
import storage.device
from trezor import io, utils
from trezor.sdcard import with_filesystem
from trezor.sdcard import with_filesystem, with_sdcard
from trezorcrypto import crc
if utils.USE_SD_CARD:
fatfs = io.fatfs # global_import_cache
sdcard = io.sdcard # global_import_cache
SDCARD_BLOCK_SIZE_B = sdcard.BLOCK_SIZE # global_import_cache
SDBACKUP_BLOCK_START = 66_138
SDBACKUP_BLOCK_START = sdcard.BACKUP_BLOCK_START # global_import_cache
SDBACKUP_BLOCK_OFFSET = 130 # TODO arbitrary for now
SDBACKUP_MAGIC = b"TRZS"
SDBACKUP_N_WRITINGS = 100 # TODO decide between offset/writings
SDBACKUP_MAGIC = b"TRZM"
SDBACKUP_VERSION = b"00"
# TODO with_filesystem can be just with_sdcard, unnecessary to mount FS for recovery
@with_filesystem
def store_seed_on_sdcard(mnemonic_secret: bytes) -> bool:
@ -29,12 +28,11 @@ def store_seed_on_sdcard(mnemonic_secret: bytes) -> bool:
return False
@with_filesystem
@with_sdcard
def recover_seed_from_sdcard() -> str | None:
return _read_seed_unalloc()
@with_filesystem
def _verify_backup(mnemonic_secret: bytes) -> bool:
mnemonic_read_plain = _read_seed_plain_text()
mnemonic_read_unalloc = _read_seed_unalloc()
@ -49,15 +47,12 @@ def _verify_backup(mnemonic_secret: bytes) -> bool:
)
@with_filesystem
def _write_seed_unalloc(mnemonic_secret: bytes) -> None:
block_to_write = _encode_mnemonic_to_backup_block(mnemonic_secret)
for block_idx in _storage_blocks_gen():
# print(f"block_idx: {block_idx}, writing: {block_to_write[10:10+4]}")
sdcard.write(block_idx, block_to_write)
@with_filesystem
def _read_seed_unalloc() -> str | None:
block_buffer = bytearray(SDCARD_BLOCK_SIZE_B)
for block_idx in _storage_blocks_gen():
@ -66,28 +61,45 @@ def _read_seed_unalloc() -> str | None:
mnemonic_read = _decode_mnemonic_from_backup_block(block_buffer)
if mnemonic_read is not None:
break
except fatfs.FatFSError:
except Exception:
return None
# print(f"_read_seed_unalloc: block_read: {block_read}")
if mnemonic_read is None:
return None
mnemonic_read_decoded = mnemonic_read.decode("utf-8").rstrip("\x00")
# print(f"_read_seed_unalloc: mnemonic_read_decoded: {mnemonic_read_decoded}")
return mnemonic_read_decoded
def _storage_blocks_gen() -> Generator:
return _storage_blocks_gen_by_n()
def _storage_blocks_gen_by_offset() -> Generator:
cap = sdcard.capacity()
if cap == 0:
raise ProcessError
BLOCK_END = cap // SDCARD_BLOCK_SIZE_B - 1
return range(SDBACKUP_BLOCK_START, BLOCK_END, SDBACKUP_BLOCK_OFFSET)
def _storage_blocks_gen_by_n() -> Generator:
cap = sdcard.capacity()
if cap == 0:
raise ProcessError
BLOCK_END = cap // SDCARD_BLOCK_SIZE_B - 1
return (
SDBACKUP_BLOCK_START
+ n * (BLOCK_END - SDBACKUP_BLOCK_START) // (SDBACKUP_N_WRITINGS - 1)
for n in range(SDBACKUP_N_WRITINGS)
)
"""
Backup Memory Block Layout:
+----------------------+----------------------+----------------------+-------------------------------+
| SDBACKUP_MAGIC (4B) | SDBACKUP_VERSION (2B)| SEED_LENGTH (4B) | MNEMONIC (variable length) |
+----------------------+----------------------+----------------------+-------------------------------+
| CHECKSUM (4B) | Padding (variable) |
+----------------------------------------------------------------------------+----------------------------+
| CHECKSUM (4B) | Padding (variable) |
+-----------------------------------------------------------------------+----------------------------+
- SDBACKUP_MAGIC: 4 bytes magic number identifying the backup block
- SDBACKUP_VERSION: 2 bytes representing the version of the backup format
@ -147,13 +159,11 @@ def _decode_mnemonic_from_backup_block(block: bytes) -> bytes | None:
return None
@with_filesystem
def _write_readme() -> None:
with fatfs.open("README.txt", "w") as f:
f.write("This is a Trezor backup SD card.")
@with_filesystem
def _write_seed_plain_text(mnemonic_secret: bytes) -> None:
# TODO to be removed, just for testing purposes
fatfs.mkdir("/trezor", True)
@ -161,7 +171,6 @@ def _write_seed_plain_text(mnemonic_secret: bytes) -> None:
f.write(mnemonic_secret)
@with_filesystem
def _read_seed_plain_text() -> str | None:
# TODO to be removed, just for testing purposes
mnemonic_read = bytearray(SDCARD_BLOCK_SIZE_B)
@ -170,5 +179,4 @@ def _read_seed_plain_text() -> str | None:
f.read(mnemonic_read)
except fatfs.FatFSError:
return None
# print(f"_read_seed_plain_text: mnemonic_read: {mnemonic_read}")
return mnemonic_read.decode("utf-8").rstrip("\x00")

13
core/src/trezor/sdcard.py
View File

@ -26,6 +26,11 @@ if TYPE_CHECKING:
R = TypeVar("R")
def is_trz_card() -> bool:
sdcard.capacity()
pass
class FilesystemWrapper:
_INSTANCE: "FilesystemWrapper" | None = None
@ -78,3 +83,11 @@ def with_filesystem(func: Callable[P, R]) -> Callable[P, R]:
return func(*args, **kwargs)
return wrapped_func
def with_sdcard(func: Callable[P, R]) -> Callable[P, R]:
def wrapped_func(*args: P.args, **kwargs: P.kwargs) -> R:
with filesystem(mounted=False):
return func(*args, **kwargs)
return wrapped_func

38
core/tests/test_storage.sd_seed_backup.py
View File

@ -1,11 +1,11 @@
from common import *
from trezorio import sdcard, fatfs
from storage.sd_seed_backup import *
from trezor import io, sdcard
class TestStorageSdSeedBackup(unittest.TestCase):
# TODO add more tests, also with partly damaged backup
# TODO add more tests, also for repairing the backup card
def setUp(self):
self.mnemonic = (
@ -16,14 +16,44 @@ class TestStorageSdSeedBackup(unittest.TestCase):
# with self.assertRaises(fatfs.FatFSError):
# store_seed_on_sdcard(self.mnemonic.encode("utf-8"))
sdcard.power_on()
fatfs.mkfs(True)
io.sdcard.power_on()
io.fatfs.mkfs(True)
io.fatfs.mount()
success = store_seed_on_sdcard(self.mnemonic.encode("utf-8"))
self.assertTrue(success)
restored = recover_seed_from_sdcard()
self.assertEqual(self.mnemonic, restored)
io.fatfs.unmount()
io.sdcard.power_off()
def test_backup_partlywipe_restore(self):
with sdcard.filesystem(mounted=True):
success = store_seed_on_sdcard(self.mnemonic.encode("utf-8"))
self.assertTrue(success)
# wipe half of the card, restore must succeed
block_buffer = bytearray(SDCARD_BLOCK_SIZE_B)
with sdcard.filesystem(mounted=False):
for block_num in range((io.sdcard.capacity() // 2) // io.sdcard.BLOCK_SIZE):
io.sdcard.write(block_num, block_buffer)
with sdcard.filesystem(mounted=False):
restored = recover_seed_from_sdcard()
self.assertEqual(self.mnemonic, restored)
# remove everything, restore fails
with sdcard.filesystem(mounted=False):
for block_num in range(io.sdcard.capacity() // io.sdcard.BLOCK_SIZE):
io.sdcard.write(block_num, block_buffer)
with sdcard.filesystem(mounted=False):
restored = recover_seed_from_sdcard()
self.assertEqual(None, restored)
if __name__ == "__main__":
unittest.main()