Nitrokey Start ID switching without sudo

Makefile

@@ -55,6 +55,7 @@ semi-clean:
 clean: semi-clean
 	rm -rf $(VENV)
 	rm -rf dist
+	rm -rf ./.mypy_cache/
 
 
 # Package management

pynitrokey/cli/start.py

@@ -6,26 +6,22 @@
 # http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
 # http://opensource.org/licenses/MIT>, at your option. This file may not be
 # copied, modified, or distributed except according to those terms.
-
-
-from subprocess import check_output
+import binascii
+import typing
 from sys import stderr, stdout
-from time import sleep
 
 import click
 from tqdm import tqdm
 from usb.core import USBError
 
+from pynitrokey.confconsts import logger
 from pynitrokey.helpers import local_critical, local_print
 from pynitrokey.start.gnuk_token import OnlyBusyICCError, get_gnuk_device
 from pynitrokey.start.threaded_log import ThreadLog
 from pynitrokey.start.upgrade_by_passwd import (
     DEFAULT_PW3,
     DEFAULT_WAIT_FOR_REENUMERATION,
     IS_LINUX,
-    kill_smartcard_services,
-    logger,
-    restart_smartcard_services,
     show_kdf_details,
     start_update,
     validate_gnuk,
@@ -93,14 +89,79 @@ def rng(count, raw, quiet):
                 print(challenge.hex())
 
 
+class CardRemovedGPGAgentException(RuntimeWarning):
+    pass
+
+
+class NoCardPCSCException(RuntimeWarning):
+    pass
+
+
+def gpg_agent_set_identity(identity: int):
+    from subprocess import check_output as run
+
+    cmd = f"gpg-connect-agent" f"|SCD APDU 00 85 00 0{identity}" f"|/bye".split("|")
+    app_out = run(cmd)
+    logger.debug(cmd)
+    logger.debug(app_out)
+    if b"ERR 100663406 Card removed" in app_out:
+        raise CardRemovedGPGAgentException("Card removed")
+
+
+def pcsc_set_identity(identity):
+    try:
+        from smartcard import System
+        from smartcard.CardConnection import CardConnection
+        from smartcard.Exceptions import NoCardException
+
+        def find_smartcard(name: typing.Optional[str] = None) -> CardConnection:
+            # use this for debug: sudo pcscd -f -a
+            for reader in System.readers():
+                if "Nitrokey Start" not in str(reader) or (
+                    name and name not in str(reader)
+                ):
+                    continue
+                conn: CardConnection
+                conn = reader.createConnection()
+                try:
+                    conn.connect()
+                except NoCardException:
+                    continue
+                logger.debug([reader, conn])
+                return conn
+            raise NoCardPCSCException(f"No smartcard with UUID {name} found")
+
+        def select(conn: CardConnection, aid: bytes) -> bool:
+            apdu = [0x00, 0xA4, 0x04, 0x00]
+            apdu.append(len(aid))
+            apdu.extend(aid)
+            _, sw1, sw2 = conn.transmit(apdu)
+            return (sw1, sw2) == (0x90, 0x00)
+
+        def send_id_change(conn: CardConnection, identity: int) -> None:
+            out = [0x00, 0x85, 0x00, identity]
+            for i in range(2):
+                data, sw1, sw2 = conn.transmit(out)
+                logger.debug((bytes(out).hex(), data, hex(sw1), hex(sw2)))
+                res = bytes([sw1, sw2]).hex()
+                if res == "9000":
+                    break
+                if res == "6a88":
+                    logger.debug(f"error: {res}")
+                    continue
+
+        conn = find_smartcard()
+        aid = binascii.a2b_hex("D276:0001:2401".replace(":", ""))
+        select(conn, aid)
+        send_id_change(conn, identity)
+
+    except ImportError:
+        logger.debug("pcsc feature is deactivated, skipping this method")
+
+
 @click.command()
 @click.argument("identity")
-@click.option(
-    "--force-restart",
-    is_flag=True,
-    help="Force pcscd and GnuPG services restart once finished",
-)
-def set_identity(identity, force_restart):
+def set_identity(identity):
     """Set given identity (one of: 0, 1, 2)
 
     Might require stopping other smart card services to connect directly to the device over CCID interface.
@@ -118,7 +179,62 @@ def set_identity(identity, force_restart):
         local_critical("identity must be 0, 1 or 2")
 
     local_print(f"Setting identity to {identity}")
-    for x in range(3):
+
+    # Note: the error in communication coming after changing the identity is caused by the immediate restart of
+    # the device, without responding to the call. The idea was to avoid operating with a potentially inconsistent state in
+    # the memory.
+    def inner() -> None:
+        """
+        Call all the methods in the order of the success chance
+        """
+
+        # this works when gpg has opened connection, stops after changing identity with it
+        try:
+            logger.info("Trying changing identity through gpg-agent")
+            gpg_agent_set_identity(identity)
+            return
+        except CardRemovedGPGAgentException:
+            # this error shows up when the identity was just changed with gpg, and the new state was not reloaded
+            pass
+
+        try:
+            from smartcard.Exceptions import CardConnectionException  # type: ignore
+            from smartcard.pcsc.PCSCExceptions import EstablishContextException
+
+            # this works when gpg has no connection, but pcsc server is working
+            try:
+                logger.info("Trying changing identity through pcscd")
+                pcsc_set_identity(identity)
+                logger.info(
+                    f"Device returns success. Identity is already set to {identity}."
+                )
+                return
+            except CardConnectionException as e:
+                logger.debug(f"Expected error. PCSC reports {e}")
+                return
+            except (EstablishContextException, NoCardPCSCException) as e:
+                logger.debug(
+                    f"pcscd must not work, try another method. Reported error: {e}"
+                )
+        except ImportError:
+            local_print("pcsc feature is deactivated, skipping this switching method")
+
+        # this works, when neither gnupg nor opensc is claiming the smart card interface
+        try:
+            logger.info("Trying changing identity through direct connection")
+            set_identity_raw(identity)
+        except:
+            raise
+
+    inner()
+    # apparently calling it 2 times reloads the gnupg, and allows for immediate use of it after changing the identity
+    # otherwise its reload is needed with gpgconf --reload all
+    inner()
+    local_print(f"Reset done - now active identity: {identity}")
+
+
+def set_identity_raw(identity):
+    for x in range(1):
         try:
             gnuk = get_gnuk_device()
             with gnuk.release_on_exit() as gnuk:
@@ -127,7 +243,7 @@ def set_identity(identity, force_restart):
                     gnuk.cmd_set_identity(identity)
                     break
                 except USBError:
-                    local_print(f"Reset done - now active identity: {identity}")
+                    logger.debug(f"Reset done - now active identity: {identity}")
                     break
 
         except OnlyBusyICCError:
@@ -137,8 +253,8 @@ def set_identity(identity, force_restart):
             break
         except ValueError as e:
             if "No ICC present" in str(e):
-                local_print(
-                    "Device is occupied by some other service and cannot be connected to. Identity not changed."
+                local_critical(
+                    "Device is not connected or occupied by some other service and cannot be connected to. Identity not changed."
                 )
             else:
                 local_critical(e)

pynitrokey/confconsts.py

@@ -36,6 +36,8 @@ class Verbosity(IntEnum):
             f"environment variable: '{ENV_DEBUG_VAR}' invalid, "
             f"setting default: {VERBOSE.name} = {VERBOSE.value}"
         )
+    print(f"Found {ENV_DEBUG_VAR}='{_env_dbg_lvl}'. Setting VERBOSE={VERBOSE}")
+
 
 LOG_FN = tempfile.NamedTemporaryFile(prefix="nitropy.log.").name
 LOG_FORMAT_STDOUT = "%(asctime)-15s %(levelname)6s %(name)10s %(message)s"
@@ -47,3 +49,10 @@ class Verbosity(IntEnum):
 UDEV_URL = (
     "https://docs.nitrokey.com/nitrokey3/linux/firmware-update.html#troubleshooting"
 )
+
+
+logger = logging.getLogger(__name__)
+stream_handler = logging.StreamHandler()
+stream_handler.setLevel(VERBOSE)
+stream_handler.setFormatter(logging.Formatter(LOG_FORMAT_STDOUT))
+logger.addHandler(stream_handler)

pyproject.toml

@@ -97,5 +97,6 @@ module = [
     "usb1.*",
     "tlv8.*",
     "pytest.*",
+    "smartcard.pcsc.*",
 ]
 ignore_missing_imports = true