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core/sd-protect: If writing to the SD card fails in request_sd_salt(), inform the user and allow them to retry or abort.

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This commit is contained in:
Andrew Kozlik 2019-10-18 13:53:00 +02:00
parent 236b6334c6
commit 39b4376b65
1 changed files with 41 additions and 42 deletions
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83
core/src/apps/common/sd_salt.py
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@ -30,7 +30,7 @@ async def _wrong_card_dialog(ctx: Optional[wire.Context]) -> None:
text.br_half()
if SD_CARD_HOT_SWAPPABLE:
text.normal("Please insert the", "correct SD card for", "this device.")
btn_confirm = "Retry"
btn_confirm = "Retry" # type: Optional[str]
btn_cancel = "Abort"
else:
text.normal("Please unplug the", "device and insert the", "correct SD card.")
@ -51,7 +51,7 @@ async def _insert_card_dialog(ctx: Optional[wire.Context]) -> None:
text.br_half()
if SD_CARD_HOT_SWAPPABLE:
text.normal("Please insert your", "SD card.")
btn_confirm = "Retry"
btn_confirm = "Retry" # type: Optional[str]
btn_cancel = "Abort"
else:
text.normal("Please unplug the", "device and insert your", "SD card.")
@ -88,6 +88,27 @@ def _get_salt_path(new: bool = False) -> str:
return "%s/salt" % _get_device_dir()
def _load_salt(fs: io.FatFS, auth_key: bytes, path: str) -> Optional[bytearray]:
# Load the salt file if it exists.
try:
with fs.open(path, "r") as f:
salt = bytearray(SD_SALT_LEN_BYTES)
stored_tag = bytearray(SD_SALT_AUTH_TAG_LEN_BYTES)
f.read(salt)
f.read(stored_tag)
except OSError:
return None
# Check the salt's authentication tag.
computed_tag = hmac.new(auth_key, salt, sha256).digest()[
:SD_SALT_AUTH_TAG_LEN_BYTES
]
if not consteq(computed_tag, stored_tag):
return None
return salt
async def request_sd_salt(
ctx: Optional[wire.Context], salt_auth_key: bytes
) -> bytearray:
@ -102,56 +123,34 @@ async def request_sd_salt(
try:
fs.mount()
# Load salt if it exists.
salt = None # type: Optional[bytearray]
try:
with fs.open(salt_path, "r") as f:
salt = bytearray(SD_SALT_LEN_BYTES)
salt_tag = bytearray(SD_SALT_AUTH_TAG_LEN_BYTES)
f.read(salt)
f.read(salt_tag)
except OSError:
salt = None
if salt is not None and consteq(
hmac.new(salt_auth_key, salt, sha256).digest()[
:SD_SALT_AUTH_TAG_LEN_BYTES
],
salt_tag,
):
salt = _load_salt(fs, salt_auth_key, salt_path)
if salt is not None:
return salt
# Load salt.new if it exists.
new_salt = None # type: Optional[bytearray]
try:
with fs.open(new_salt_path, "r") as f:
new_salt = bytearray(SD_SALT_LEN_BYTES)
new_salt_tag = bytearray(SD_SALT_AUTH_TAG_LEN_BYTES)
f.read(new_salt)
f.read(new_salt_tag)
except OSError:
new_salt = None
if new_salt is not None and consteq(
hmac.new(salt_auth_key, new_salt, sha256).digest()[
:SD_SALT_AUTH_TAG_LEN_BYTES
],
new_salt_tag,
):
# Check if there is a new salt.
salt = _load_salt(fs, salt_auth_key, new_salt_path)
if salt is not None:
# SD salt regeneration was interrupted earlier. Bring into consistent state.
# TODO Possibly overwrite salt file with random data.
try:
fs.unlink(salt_path)
except OSError:
pass
fs.rename(new_salt_path, salt_path)
return new_salt
try:
fs.rename(new_salt_path, salt_path)
except OSError:
error_dialog = _write_failed_dialog(ctx)
else:
return salt
else:
# No valid salt file on this SD card.
error_dialog = _wrong_card_dialog(ctx)
finally:
fs.unmount()
sd.power(False)
await _wrong_card_dialog(ctx)
await error_dialog
async def set_sd_salt(
@ -195,7 +194,7 @@ async def commit_sd_salt(ctx: Optional[wire.Context]) -> None:
sd = io.SDCard()
fs = io.FatFS()
if not sd.power(True):
raise IOError
raise OSError
try:
fs.mount()
@ -216,7 +215,7 @@ async def remove_sd_salt(ctx: Optional[wire.Context]) -> None:
sd = io.SDCard()
fs = io.FatFS()
if not sd.power(True):
raise IOError
raise OSError
try:
fs.mount()