Andrew Kozlik
5 years ago
parent
f867b43251
commit
6350b1c61c
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from micropython import const
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from trezor import io, ui, wire
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from trezor.crypto import hmac
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from trezor.crypto.hashlib import sha256
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from trezor.ui.confirm import Confirm
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from trezor.ui.text import Text
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from trezor.utils import consteq
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from apps.common import storage
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from apps.common.confirm import require_confirm
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if False:
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from typing import Optional
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class SdProtectCancelled(Exception):
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pass
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SD_SALT_LEN_BYTES = const(32)
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SD_SALT_AUTH_TAG_LEN_BYTES = const(16)
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SD_SALT_AUTH_KEY_LEN_BYTES = const(16)
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async def wrong_card_dialog(ctx: Optional[wire.Context]) -> None:
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text = Text("SD card protection", ui.ICON_WRONG)
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text.bold("Wrong SD card.")
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text.br_half()
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text.normal("Please unplug the", "device and insert a", "different card.")
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if ctx is None:
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await Confirm(text, confirm=None)
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else:
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await require_confirm(ctx, text, confirm=None)
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async def insert_card_dialog(ctx: Optional[wire.Context]) -> None:
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text = Text("SD card protection")
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text.bold("SD card required.")
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text.br_half()
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text.normal("Please unplug the", "device and insert your", "SD card.")
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if ctx is None:
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await Confirm(text, confirm=None)
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else:
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await require_confirm(ctx, text, confirm=None)
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async def request_sd_salt(
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ctx: Optional[wire.Context], salt_auth_key: bytes
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) -> bytearray:
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device_dir = "/trezor/device_%s" % storage.device.get_device_id()
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salt_path = "%s/salt" % device_dir
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new_salt_path = "%s/salt.new" % device_dir
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sd = io.SDCard()
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fs = io.FatFS()
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if not sd.power(True):
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await insert_card_dialog(ctx)
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raise SdProtectCancelled
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try:
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fs.mount()
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# Load salt if it exists.
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try:
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with fs.open(salt_path, "r") as f:
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salt = bytearray(SD_SALT_LEN_BYTES) # type: Optional[bytearray]
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salt_tag = bytearray(SD_SALT_AUTH_TAG_LEN_BYTES)
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f.read(salt)
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f.read(salt_tag)
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except OSError:
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salt = None
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if salt is not None and consteq(
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hmac.new(salt_auth_key, salt, sha256).digest()[:SD_SALT_AUTH_TAG_LEN_BYTES],
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salt_tag,
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):
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return salt
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# Load salt.new if it exists.
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try:
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with fs.open(new_salt_path, "r") as f:
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new_salt = bytearray(SD_SALT_LEN_BYTES) # type: Optional[bytearray]
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new_salt_tag = bytearray(SD_SALT_AUTH_TAG_LEN_BYTES)
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f.read(new_salt)
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f.read(new_salt_tag)
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except OSError:
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new_salt = None
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if new_salt is not None and consteq(
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hmac.new(salt_auth_key, new_salt, sha256).digest()[
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:SD_SALT_AUTH_TAG_LEN_BYTES
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],
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new_salt_tag,
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):
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# SD salt regeneration was interrupted earlier. Bring into consistent state.
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# TODO Possibly overwrite salt file with random data.
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try:
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fs.unlink(salt_path)
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except OSError:
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pass
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fs.rename(new_salt_path, salt_path)
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return new_salt
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finally:
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fs.unmount()
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sd.power(False)
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await wrong_card_dialog(ctx)
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raise SdProtectCancelled
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async def set_sd_salt(
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ctx: Optional[wire.Context], salt: bytes, salt_tag: bytes, filename: str = "salt"
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) -> None:
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device_dir = "/trezor/device_%s" % storage.device.get_device_id()
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salt_path = "%s/%s" % (device_dir, filename)
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sd = io.SDCard()
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fs = io.FatFS()
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if not sd.power(True):
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await insert_card_dialog(ctx)
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raise SdProtectCancelled
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try:
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fs.mount()
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try:
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fs.mkdir("/trezor")
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except OSError:
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# Directory already exists.
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pass
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try:
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fs.mkdir(device_dir)
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except OSError:
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# Directory already exists.
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pass
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with fs.open(salt_path, "w") as f:
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f.write(salt)
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f.write(salt_tag)
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finally:
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fs.unmount()
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sd.power(False)
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async def stage_sd_salt(
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ctx: Optional[wire.Context], salt: bytes, salt_tag: bytes
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) -> None:
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await set_sd_salt(ctx, salt, salt_tag, "salt.new")
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async def commit_sd_salt(ctx: Optional[wire.Context]) -> None:
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device_dir = "/trezor/device_%s" % storage.device.get_device_id()
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salt_path = "%s/salt" % device_dir
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new_salt_path = "%s/salt.new" % device_dir
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sd = io.SDCard()
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fs = io.FatFS()
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if not sd.power(True):
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await insert_card_dialog(ctx)
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raise SdProtectCancelled
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try:
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fs.mount()
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# TODO Possibly overwrite salt file with random data.
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try:
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fs.unlink(salt_path)
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except OSError:
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pass
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fs.rename(new_salt_path, salt_path)
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finally:
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fs.unmount()
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sd.power(False)
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async def remove_sd_salt(ctx: Optional[wire.Context]) -> None:
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device_dir = "/trezor/device_%s" % storage.device.get_device_id()
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salt_path = "%s/salt" % device_dir
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sd = io.SDCard()
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fs = io.FatFS()
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if not sd.power(True):
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await insert_card_dialog(ctx)
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raise SdProtectCancelled
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try:
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fs.mount()
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# TODO Possibly overwrite salt file with random data.
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fs.unlink(salt_path)
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finally:
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fs.unmount()
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sd.power(False)
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@ -0,0 +1,169 @@
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from trezor import config, ui, wire
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from trezor.crypto import hmac, random
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from trezor.crypto.hashlib import sha256
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from trezor.messages import SdProtectOperationType
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from trezor.messages.Success import Success
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from trezor.pin import pin_to_int
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from trezor.ui.text import Text
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from apps.common.confirm import require_confirm
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from apps.common.sd_salt import (
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SD_SALT_AUTH_KEY_LEN_BYTES,
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SD_SALT_AUTH_TAG_LEN_BYTES,
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SD_SALT_LEN_BYTES,
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commit_sd_salt,
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remove_sd_salt,
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set_sd_salt,
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stage_sd_salt,
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)
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from apps.common.storage import device, is_initialized
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from apps.management.change_pin import request_pin_ack, request_pin_and_sd_salt
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if False:
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from trezor.messages.SdProtect import SdProtect
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async def sd_protect(ctx: wire.Context, msg: SdProtect) -> Success:
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if not is_initialized():
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raise wire.ProcessError("Device is not initialized")
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if msg.operation == SdProtectOperationType.ENABLE:
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return await sd_protect_enable(ctx, msg)
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elif msg.operation == SdProtectOperationType.DISABLE:
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return await sd_protect_disable(ctx, msg)
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elif msg.operation == SdProtectOperationType.REFRESH:
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return await sd_protect_refresh(ctx, msg)
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else:
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raise wire.ProcessError("Unknown operation")
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async def sd_protect_enable(ctx: wire.Context, msg: SdProtect) -> Success:
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salt_auth_key = device.get_sd_salt_auth_key()
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if salt_auth_key is not None:
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raise wire.ProcessError("SD card protection already enabled")
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# Confirm that user wants to proceed with the operation.
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await require_confirm_sd_protect(ctx, msg)
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# Get the current PIN.
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if config.has_pin():
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pin = pin_to_int(await request_pin_ack(ctx, "Enter PIN", config.get_pin_rem()))
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else:
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pin = pin_to_int("")
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# Check PIN and prepare salt file.
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salt = random.bytes(SD_SALT_LEN_BYTES)
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salt_auth_key = random.bytes(SD_SALT_AUTH_KEY_LEN_BYTES)
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salt_tag = hmac.new(salt_auth_key, salt, sha256).digest()[
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:SD_SALT_AUTH_TAG_LEN_BYTES
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]
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try:
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await set_sd_salt(ctx, salt, salt_tag)
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except Exception:
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raise wire.ProcessError("Failed to write to SD card")
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if not config.change_pin(pin, pin, None, salt):
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# Wrong PIN. Clean up the prepared salt file.
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try:
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await remove_sd_salt(ctx)
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except Exception:
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# The cleanup is not necessary for the correct functioning of
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# SD-protection. If it fails for any reason, we suppress the
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# exception, because primarily we need to raise wire.PinInvalid.
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pass
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raise wire.PinInvalid("PIN invalid")
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device.set_sd_salt_auth_key(salt_auth_key)
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return Success(message="SD card protection enabled")
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async def sd_protect_disable(ctx: wire.Context, msg: SdProtect) -> Success:
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if device.get_sd_salt_auth_key() is None:
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raise wire.ProcessError("SD card protection not enabled")
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# Confirm that user wants to proceed with the operation.
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await require_confirm_sd_protect(ctx, msg)
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# Get the current PIN and salt from the SD card.
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pin, salt = await request_pin_and_sd_salt(ctx, "Enter PIN")
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# Check PIN and remove salt.
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if not config.change_pin(pin_to_int(pin), pin_to_int(pin), salt, None):
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raise wire.PinInvalid("PIN invalid")
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device.set_sd_salt_auth_key(None)
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try:
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# Clean up.
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await remove_sd_salt(ctx)
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except Exception:
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# The cleanup is not necessary for the correct functioning of
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# SD-protection. If it fails for any reason, we suppress the exception,
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# because overall SD-protection was successfully disabled.
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pass
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return Success(message="SD card protection disabled")
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async def sd_protect_refresh(ctx: wire.Context, msg: SdProtect) -> Success:
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if device.get_sd_salt_auth_key() is None:
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raise wire.ProcessError("SD card protection not enabled")
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# Confirm that user wants to proceed with the operation.
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await require_confirm_sd_protect(ctx, msg)
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# Get the current PIN and salt from the SD card.
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pin, old_salt = await request_pin_and_sd_salt(ctx, "Enter PIN")
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# Check PIN and change salt.
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new_salt = random.bytes(SD_SALT_LEN_BYTES)
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new_salt_auth_key = random.bytes(SD_SALT_AUTH_KEY_LEN_BYTES)
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new_salt_tag = hmac.new(new_salt_auth_key, new_salt, sha256).digest()[
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:SD_SALT_AUTH_TAG_LEN_BYTES
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]
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try:
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await stage_sd_salt(ctx, new_salt, new_salt_tag)
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except Exception:
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raise wire.ProcessError("Failed to write to SD card")
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if not config.change_pin(pin_to_int(pin), pin_to_int(pin), old_salt, new_salt):
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raise wire.PinInvalid("PIN invalid")
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device.set_sd_salt_auth_key(new_salt_auth_key)
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try:
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# Clean up.
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await commit_sd_salt(ctx)
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except Exception:
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# If the cleanup fails, then request_sd_salt() will bring the SD card
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# into a consistent state. We suppress the exception, because overall
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# SD-protection was successfully refreshed.
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pass
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return Success(message="SD card protection refreshed")
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def require_confirm_sd_protect(ctx: wire.Context, msg: SdProtect) -> None:
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if msg.operation == SdProtectOperationType.ENABLE:
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text = Text("SD card protection", ui.ICON_CONFIG)
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text.normal(
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"Do you really want to", "secure your device with", "SD card protection?"
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)
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elif msg.operation == SdProtectOperationType.DISABLE:
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text = Text("SD card protection", ui.ICON_CONFIG)
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text.normal(
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"Do you really want to", "remove SD card", "protection from your", "device?"
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)
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elif msg.operation == SdProtectOperationType.REFRESH:
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text = Text("SD card protection", ui.ICON_CONFIG)
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text.normal(
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"Do you really want to",
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"replace the current",
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"SD card secret with a",
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"newly generated one?",
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)
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else:
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raise wire.ProcessError("Unknown operation")
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return require_confirm(ctx, text)
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