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core/webauthn: Fix handling of interleaving frames to comply with the U2F HID specification.

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This commit is contained in:
Andrew Kozlik 2020-04-03 17:42:49 +02:00 committed by Andrew Kozlik
parent e6d884b145
commit 25a39ea729
1 changed files with 43 additions and 6 deletions
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49
core/src/apps/webauthn/fido2.py
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@ -41,6 +41,7 @@ _HID_RPT_SIZE = const(64)
_FRAME_INIT_SIZE = const(57)
_FRAME_CONT_SIZE = const(59)
_MAX_U2FHID_MSG_PAYLOAD_LEN = const(_FRAME_INIT_SIZE + 128 * _FRAME_CONT_SIZE)
_CMD_INIT_NONCE_SIZE = const(8)
# types of cmd
_CMD_PING = const(0x81) # echo data through local processor only
@ -418,20 +419,53 @@ async def read_cmd(iface: io.HID) -> Optional[Cmd]:
while datalen < bcnt:
buf = await loop.race(read, loop.sleep(_CTAP_HID_TIMEOUT_MS * 1000))
if not isinstance(buf, bytes):
if __debug__:
log.warning(__name__, "_ERR_MSG_TIMEOUT")
await send_cmd(cmd_error(ifrm.cid, _ERR_MSG_TIMEOUT), iface)
return None
cfrm = overlay_struct(bytearray(buf), desc_cont)
if cfrm.seq == _CMD_INIT:
# _CMD_INIT frame, cancels current channel
break
if cfrm.cid == ifrm.cid:
# _CMD_INIT command on current channel, abort current transaction.
if __debug__:
log.warning(
__name__,
"U2FHID: received CMD_INIT command during active tran, aborting",
)
break
else:
# _CMD_INIT command on different channel, return synchronization response, but continue on current CID.
if __debug__:
log.info(
__name__,
"U2FHID: received CMD_INIT command for different CID",
)
cfrm = overlay_struct(bytearray(buf), desc_init)
await send_cmd(
cmd_init(
Cmd(cfrm.cid, cfrm.cmd, bytes(cfrm.data[: cfrm.bcnt]))
),
iface,
)
continue
if cfrm.cid != ifrm.cid:
# cont frame for a different channel, reply with BUSY and abort
if __debug__:
log.warning(__name__, "_ERR_CHANNEL_BUSY")
await send_cmd(cmd_error(cfrm.cid, _ERR_CHANNEL_BUSY), iface)
# Frame for a different channel, continue waiting for next frame on the active CID.
# For init frames reply with BUSY. Ignore continuation frames.
if cfrm.seq & _TYPE_MASK == _TYPE_INIT:
if __debug__:
log.warning(
__name__,
"U2FHID: received init frame for different CID, _ERR_CHANNEL_BUSY",
)
await send_cmd(cmd_error(cfrm.cid, _ERR_CHANNEL_BUSY), iface)
else:
if __debug__:
log.warning(
__name__, "U2FHID: received cont frame for different CID"
)
continue
if cfrm.seq != seq:
@ -1099,6 +1133,9 @@ def cmd_init(req: Cmd) -> Cmd:
else:
resp_cid = req.cid
if len(req.data) != _CMD_INIT_NONCE_SIZE:
return cmd_error(req.cid, _ERR_INVALID_LEN)
buf, resp = make_struct(resp_cmd_init())
utils.memcpy(resp.nonce, 0, req.data, 0, len(req.data))
resp.cid = resp_cid