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Code Issues Releases Wiki Activity

wip buffer locking-

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[no changelog]
This commit is contained in:
M1nd3r 2024-12-11 11:46:55 +01:00
parent 62ee3fe3b1
commit beb8b58064
4 changed files with 226 additions and 161 deletions
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1
core/src/trezor/wire/thp/__init__.py
View File

@ -67,6 +67,7 @@ class ChannelState(IntEnum):
TP4 = 6
TC1 = 7
ENCRYPTED_TRANSPORT = 8
INVALIDATED = 9
class SessionState(IntEnum):

104
core/src/trezor/wire/thp/channel.py
View File

@ -8,7 +8,12 @@ from storage.cache_common import (
CHANNEL_NONCE_RECEIVE,
CHANNEL_NONCE_SEND,
)
from storage.cache_thp import TAG_LENGTH, ChannelCache, clear_sessions_with_channel_id
from storage.cache_thp import (
SESSION_ID_LENGTH,
TAG_LENGTH,
ChannelCache,
clear_sessions_with_channel_id,
)
from trezor import log, loop, protobuf, utils, workflow
from . import ENCRYPTED, ChannelState, PacketHeader, ThpDecryptionError, ThpError
@ -25,6 +30,7 @@ from .transmission_loop import TransmissionLoop
from .writer import (
CONT_HEADER_LENGTH,
INIT_HEADER_LENGTH,
MESSAGE_TYPE_LENGTH,
PACKET_LENGTH,
write_payload_to_wire_and_add_checksum,
)
@ -58,6 +64,7 @@ class Channel:
# Shared variables
self.buffer: utils.BufferType = bytearray(PACKET_LENGTH)
self.fallback_decrypt: bool = False
self.bytes_read: int = 0
self.expected_payload_length: int = 0
self.is_cont_packet_expected: bool = False
@ -97,24 +104,25 @@ class Channel:
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("set_channel_state: ", state_to_str(state))
def set_buffer(self, buffer: utils.BufferType) -> None:
self.buffer = buffer
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("set_buffer: ", str(type(self.buffer)))
# READ and DECRYPT
def receive_packet(self, packet: utils.BufferType) -> Awaitable[None] | None:
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("receive packet")
self._handle_received_packet(packet)
try:
buffer = memory_manager.get_existing_read_buffer(self.get_channel_id_int())
except BufferError:
pass # TODO ??
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("self.buffer: ", get_bytes_as_str(self.buffer))
self._log("self.buffer: ", get_bytes_as_str(buffer))
if self.expected_payload_length + INIT_HEADER_LENGTH == self.bytes_read:
self._finish_message()
return received_message_handler.handle_received_message(self, self.buffer)
return received_message_handler.handle_received_message(self, buffer)
elif self.expected_payload_length + INIT_HEADER_LENGTH > self.bytes_read:
self.is_cont_packet_expected = True
else:
@ -136,7 +144,9 @@ class Channel:
# ctrl_byte, _, payload_length = ustruct.unpack(PacketHeader.format_str_init, packet) # TODO use this with single packet decryption
_, _, payload_length = ustruct.unpack(PacketHeader.format_str_init, packet)
self.expected_payload_length = payload_length
packet_payload = memoryview(packet)[INIT_HEADER_LENGTH:]
# packet_payload = memoryview(packet)[INIT_HEADER_LENGTH:]
# The above could be used for single packet decryption
# If the channel does not "own" the buffer lock, decrypt first packet
# TODO do it only when needed!
@ -147,18 +157,22 @@ class Channel:
# if control_byte.is_encrypted_transport(ctrl_byte):
# packet_payload = self._decrypt_single_packet_payload(packet_payload)
self.buffer = memory_manager.select_buffer(
self.get_channel_state(),
self.buffer,
packet_payload,
payload_length,
)
cid = self.get_channel_id_int()
length = payload_length + INIT_HEADER_LENGTH
try:
buffer = memory_manager.get_new_read_buffer(cid, length)
except BufferError:
self.fallback_decrypt = True
# TODO decrypt packet by packet, keep track of length, at the end call _finish_message to clear mess
# if buffer is BufferError:
# pass # TODO handle deviceBUSY
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("handle_init_packet - payload len: ", str(payload_length))
self._log("handle_init_packet - buffer len: ", str(len(self.buffer)))
self._log("handle_init_packet - buffer len: ", str(len(buffer)))
return self._buffer_packet_data(self.buffer, packet, 0)
self._buffer_packet_data(buffer, packet, 0)
def _handle_cont_packet(self, packet: utils.BufferType) -> None:
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
@ -166,7 +180,12 @@ class Channel:
if not self.is_cont_packet_expected:
raise ThpError("Continuation packet is not expected, ignoring")
return self._buffer_packet_data(self.buffer, packet, CONT_HEADER_LENGTH)
try:
buffer = memory_manager.get_existing_read_buffer(self.get_channel_id_int())
except BufferError:
pass # TODO handle device busy, channel kaput
return self._buffer_packet_data(buffer, packet, CONT_HEADER_LENGTH)
def _buffer_packet_data(
self, payload_buffer: utils.BufferType, packet: utils.BufferType, offset: int
@ -174,6 +193,7 @@ class Channel:
self.bytes_read += utils.memcpy(payload_buffer, self.bytes_read, packet, offset)
def _finish_message(self) -> None:
self.fallback_decrypt = False
self.bytes_read = 0
self.expected_payload_length = 0
self.is_cont_packet_expected = False
@ -187,15 +207,19 @@ class Channel:
def decrypt_buffer(
self, message_length: int, offset: int = INIT_HEADER_LENGTH
) -> None:
noise_buffer = memoryview(self.buffer)[
buffer = memory_manager.get_existing_read_buffer(self.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO handle deviceBUSY
noise_buffer = memoryview(buffer)[
offset : message_length - CHECKSUM_LENGTH - TAG_LENGTH
]
tag = self.buffer[
tag = buffer[
message_length
- CHECKSUM_LENGTH
- TAG_LENGTH : message_length
- CHECKSUM_LENGTH
]
if utils.DISABLE_ENCRYPTION:
is_tag_valid = tag == crypto.DUMMY_TAG
else:
@ -234,11 +258,33 @@ class Channel:
if __debug__ and utils.EMULATOR:
self._log(f"write message: {msg.MESSAGE_NAME}\n", utils.dump_protobuf(msg))
self.buffer = memory_manager.get_write_buffer(self.buffer, msg)
noise_payload_len = memory_manager.encode_into_buffer(
self.buffer, msg, session_id
)
return self._write_and_encrypt(self.buffer[:noise_payload_len])
cid = self.get_channel_id_int()
msg_size = protobuf.encoded_length(msg)
payload_size = SESSION_ID_LENGTH + MESSAGE_TYPE_LENGTH + msg_size
length = payload_size + CHECKSUM_LENGTH + TAG_LENGTH + INIT_HEADER_LENGTH
try:
buffer = memory_manager.get_new_write_buffer(cid, length)
noise_payload_len = memory_manager.encode_into_buffer(
buffer, msg, session_id
)
except BufferError:
from trezor.messages import Failure, FailureType
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
self._log("Failed to get write buffer, killing channel.")
noise_payload_len = memory_manager.encode_into_buffer(
self.buffer,
Failure(
code=FailureType.FirmwareError,
message="Failed to obtain write buffer.",
),
session_id,
)
self.set_channel_state(ChannelState.INVALIDATED)
return self._write_and_encrypt(buffer[:noise_payload_len])
return self._write_and_encrypt(buffer[:noise_payload_len])
def write_error(self, err_type: int) -> Awaitable[None]:
msg_data = err_type.to_bytes(1, "big")
@ -254,7 +300,11 @@ class Channel:
def _write_and_encrypt(self, payload: bytes) -> Awaitable[None]:
payload_length = len(payload)
self._encrypt(self.buffer, payload_length)
buffer = memory_manager.get_existing_write_buffer(self.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO handle deviceBUSY
self._encrypt(buffer, payload_length)
payload_length = payload_length + TAG_LENGTH
if self.write_task_spawn is not None:
@ -263,7 +313,7 @@ class Channel:
self._prepare_write()
self.write_task_spawn = loop.spawn(
self._write_encrypted_payload_loop(
ENCRYPTED, memoryview(self.buffer[:payload_length])
ENCRYPTED, memoryview(buffer[:payload_length])
)
)
return self.write_task_spawn

251
core/src/trezor/wire/thp/memory_manager.py
View File

@ -1,70 +1,150 @@
from storage.cache_thp import SESSION_ID_LENGTH, TAG_LENGTH
from trezor import log, protobuf, utils
import utime
from micropython import const
from storage.cache_thp import SESSION_ID_LENGTH
from trezor import protobuf, utils
from trezor.wire.message_handler import get_msg_type
from . import ChannelState, ThpError
from .checksum import CHECKSUM_LENGTH
from .writer import (
INIT_HEADER_LENGTH,
MAX_PAYLOAD_LEN,
MESSAGE_TYPE_LENGTH,
PACKET_LENGTH,
)
from . import ThpError
from .writer import MAX_PAYLOAD_LEN, MESSAGE_TYPE_LENGTH
_PROTOBUF_BUFFER_SIZE = 8192
READ_BUFFER = bytearray(_PROTOBUF_BUFFER_SIZE)
WRITE_BUFFER = bytearray(_PROTOBUF_BUFFER_SIZE)
def select_buffer(
channel_state: int,
channel_buffer: utils.BufferType,
packet_payload: utils.BufferType,
payload_length: int,
) -> utils.BufferType:
lock_owner_cid: int | None = None
lock_time: int = 0
if channel_state is ChannelState.ENCRYPTED_TRANSPORT:
session_id = packet_payload[0]
if session_id == 0:
pass
# TODO use small buffer
else:
pass
# TODO use big buffer but only if the channel owns the buffer lock.
# Otherwise send BUSY message and return
READ_BUFFER_SLICE: memoryview | None = None
WRITE_BUFFER_SLICE: memoryview | None = None
# Buffer types
_READ: int = const(0)
_WRITE: int = const(1)
#
# Access to buffer slices
def get_new_read_buffer(channel_id: int, length: int) -> memoryview:
return _get_new_buffer(_READ, channel_id, length)
def get_new_write_buffer(channel_id: int, length: int) -> memoryview:
return _get_new_buffer(_WRITE, channel_id, length)
def get_existing_read_buffer(channel_id: int) -> memoryview:
return _get_existing_buffer(_READ, channel_id)
def get_existing_write_buffer(channel_id: int) -> memoryview:
return _get_existing_buffer(_WRITE, channel_id)
def _get_new_buffer(buffer_type: int, channel_id: int, length: int) -> memoryview:
if is_locked():
if not is_owner(channel_id):
raise BufferError
update_lock_time()
else:
pass
# TODO use small buffer
try:
# TODO for now, we create a new big buffer every time. It should be changed
buffer: utils.BufferType = _get_buffer_for_read(payload_length, channel_buffer)
return buffer
except Exception as e:
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.exception(__name__, e)
raise Exception("Failed to create a buffer for channel") # TODO handle better
update_lock(channel_id)
if buffer_type == _READ:
global READ_BUFFER
buffer = READ_BUFFER
elif buffer_type == _WRITE:
global WRITE_BUFFER
buffer = WRITE_BUFFER
else:
raise Exception("Invalid buffer_type")
if length > MAX_PAYLOAD_LEN or length > len(buffer):
raise ThpError("Message is too large") # TODO reword
if buffer_type == _READ:
global READ_BUFFER_SLICE
READ_BUFFER_SLICE = memoryview(READ_BUFFER)[:length]
return READ_BUFFER_SLICE
if buffer_type == _WRITE:
global WRITE_BUFFER_SLICE
WRITE_BUFFER_SLICE = memoryview(WRITE_BUFFER)[:length]
return WRITE_BUFFER_SLICE
raise Exception("Invalid buffer_type")
def get_write_buffer(
buffer: utils.BufferType, msg: protobuf.MessageType
) -> utils.BufferType:
msg_size = protobuf.encoded_length(msg)
payload_size = SESSION_ID_LENGTH + MESSAGE_TYPE_LENGTH + msg_size
required_min_size = payload_size + CHECKSUM_LENGTH + TAG_LENGTH
def _get_existing_buffer(buffer_type: int, channel_id: int) -> memoryview:
if not is_owner(channel_id):
raise BufferError
update_lock_time()
if required_min_size > len(buffer):
return _get_buffer_for_write(required_min_size, buffer)
return buffer
if buffer_type == _READ:
global READ_BUFFER_SLICE
if READ_BUFFER_SLICE is None:
raise BufferError
return READ_BUFFER_SLICE
if buffer_type == _WRITE:
global WRITE_BUFFER_SLICE
if WRITE_BUFFER_SLICE is None:
raise BufferError
return WRITE_BUFFER_SLICE
raise Exception("Invalid buffer_type")
#
# Buffer locking
def is_locked() -> bool:
global lock_owner_cid
global lock_time
time_diff = utime.ticks_diff(utime.ticks_ms(), lock_time)
return lock_owner_cid is not None and time_diff < 200
def is_owner(channel_id: int) -> bool:
global lock_owner_cid
return lock_owner_cid is not None and lock_owner_cid == channel_id
def update_lock(channel_id: int) -> None:
set_owner(channel_id)
update_lock_time()
def set_owner(channel_id: int) -> None:
global lock_owner_cid
lock_owner_cid = channel_id
def update_lock_time() -> None:
global lock_time
lock_time = utime.ticks_ms()
#
# Helper for encoding messages into buffer
def encode_into_buffer(
buffer: utils.BufferType, msg: protobuf.MessageType, session_id: int
) -> int:
"""Encode protobuf message `msg` into the `buffer`, including session id
an messages's wire type. Will fail if provided message has no wire type."""
# cannot write message without wire type
msg_type = msg.MESSAGE_WIRE_TYPE
if msg_type is None:
msg_type = get_msg_type(msg.MESSAGE_NAME)
assert msg_type is not None
if msg_type is None:
raise Exception("Message has no wire type.")
msg_size = protobuf.encoded_length(msg)
payload_size = SESSION_ID_LENGTH + MESSAGE_TYPE_LENGTH + msg_size
@ -96,84 +176,3 @@ def _encode_message_into_buffer(
buffer: memoryview, message: protobuf.MessageType, buffer_offset: int = 0
) -> None:
protobuf.encode(memoryview(buffer[buffer_offset:]), message)
def _get_buffer_for_read(
payload_length: int,
existing_buffer: utils.BufferType,
max_length: int = MAX_PAYLOAD_LEN,
) -> utils.BufferType:
length = payload_length + INIT_HEADER_LENGTH
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(
__name__,
"get_buffer_for_read - length: %d, %s %s",
length,
"existing buffer type:",
type(existing_buffer),
)
if length > max_length:
raise ThpError("Message too large")
if length > len(existing_buffer):
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(__name__, "Allocating a new buffer")
if length > len(READ_BUFFER):
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(
__name__,
"Required length is %d, where raw buffer has capacity only %d",
length,
len(READ_BUFFER),
)
raise ThpError("Message is too large")
try:
payload: utils.BufferType = memoryview(READ_BUFFER)[:length]
except MemoryError:
payload = memoryview(READ_BUFFER)[:PACKET_LENGTH]
raise ThpError("Message is too large")
return payload
# reuse a part of the supplied buffer
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(__name__, "Reusing already allocated buffer")
return memoryview(existing_buffer)[:length]
def _get_buffer_for_write(
payload_length: int,
existing_buffer: utils.BufferType,
max_length: int = MAX_PAYLOAD_LEN,
) -> utils.BufferType:
length = payload_length + INIT_HEADER_LENGTH
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(
__name__,
"get_buffer_for_write - length: %d, %s %s",
length,
"existing buffer type:",
type(existing_buffer),
)
if length > max_length:
raise ThpError("Message too large")
if length > len(existing_buffer):
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(__name__, "Creating a new write buffer from raw write buffer")
if length > len(WRITE_BUFFER):
raise ThpError("Message is too large")
try:
payload: utils.BufferType = memoryview(WRITE_BUFFER)[:length]
except MemoryError:
payload = memoryview(WRITE_BUFFER)[:PACKET_LENGTH]
raise ThpError("Message is too large")
return payload
# reuse a part of the supplied buffer
if __debug__ and utils.ALLOW_DEBUG_MESSAGES:
log.debug(__name__, "Reusing already allocated buffer")
return memoryview(existing_buffer)[:length]

31
core/src/trezor/wire/thp/received_message_handler.py
View File

@ -18,6 +18,7 @@ from storage.cache_thp import (
from trezor import log, loop, protobuf, utils
from trezor.enums import FailureType
from trezor.messages import Failure
from trezor.wire.thp import memory_manager
from .. import message_handler
from ..errors import DataError
@ -227,8 +228,12 @@ async def _handle_state_TH1(
ctx.handshake = Handshake()
buffer = memory_manager.get_existing_read_buffer(ctx.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO buffer is gone :/
host_ephemeral_pubkey = bytearray(
ctx.buffer[INIT_HEADER_LENGTH : message_length - CHECKSUM_LENGTH]
buffer[INIT_HEADER_LENGTH : message_length - CHECKSUM_LENGTH]
)
trezor_ephemeral_pubkey, encrypted_trezor_static_pubkey, tag = (
ctx.handshake.handle_th1_crypto(
@ -267,10 +272,13 @@ async def _handle_state_TH2(ctx: Channel, message_length: int, ctrl_byte: int) -
if ctx.handshake is None:
raise Exception("Handshake object is not prepared. Retry handshake.")
host_encrypted_static_pubkey = memoryview(ctx.buffer)[
buffer = memory_manager.get_existing_read_buffer(ctx.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO handle
host_encrypted_static_pubkey = buffer[
INIT_HEADER_LENGTH : INIT_HEADER_LENGTH + KEY_LENGTH + TAG_LENGTH
]
handshake_completion_request_noise_payload = memoryview(ctx.buffer)[
handshake_completion_request_noise_payload = buffer[
INIT_HEADER_LENGTH + KEY_LENGTH + TAG_LENGTH : message_length - CHECKSUM_LENGTH
]
@ -285,7 +293,7 @@ async def _handle_state_TH2(ctx: Channel, message_length: int, ctrl_byte: int) -
ctx.channel_cache.set_int(CHANNEL_NONCE_SEND, 1)
noise_payload = _decode_message(
ctx.buffer[
buffer[
INIT_HEADER_LENGTH
+ KEY_LENGTH
+ TAG_LENGTH : message_length
@ -349,8 +357,12 @@ async def _handle_state_ENCRYPTED_TRANSPORT(ctx: Channel, message_length: int) -
log.debug(__name__, "handle_state_ENCRYPTED_TRANSPORT")
ctx.decrypt_buffer(message_length)
buffer = memory_manager.get_existing_read_buffer(ctx.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO handle
session_id, message_type = ustruct.unpack(
">BH", memoryview(ctx.buffer)[INIT_HEADER_LENGTH:]
">BH", memoryview(buffer)[INIT_HEADER_LENGTH:]
)
if session_id not in ctx.sessions:
@ -372,7 +384,7 @@ async def _handle_state_ENCRYPTED_TRANSPORT(ctx: Channel, message_length: int) -
s.incoming_message.put(
Message(
message_type,
ctx.buffer[
buffer[
INIT_HEADER_LENGTH
+ MESSAGE_TYPE_LENGTH
+ SESSION_ID_LENGTH : message_length
@ -391,14 +403,17 @@ async def _handle_pairing(ctx: Channel, message_length: int) -> None:
loop.schedule(ctx.connection_context.handle())
ctx.decrypt_buffer(message_length)
buffer = memory_manager.get_existing_read_buffer(ctx.get_channel_id_int())
# if buffer is BufferError:
# pass # TODO handle
message_type = ustruct.unpack(
">H", ctx.buffer[INIT_HEADER_LENGTH + SESSION_ID_LENGTH :]
">H", buffer[INIT_HEADER_LENGTH + SESSION_ID_LENGTH :]
)[0]
ctx.connection_context.incoming_message.put(
Message(
message_type,
ctx.buffer[
buffer[
INIT_HEADER_LENGTH
+ MESSAGE_TYPE_LENGTH
+ SESSION_ID_LENGTH : message_length