core: Implement credential management.

core/src/apps/common/storage/webauthn.py

@@ -10,37 +10,48 @@ _RESIDENT_CREDENTIAL_START_KEY = const(1)
 _MAX_RESIDENT_CREDENTIALS = const(16)
 
 
-def get_resident_credentials(rp_id_hash: Optional[bytes]) -> List[Credential]:
+def get_resident_credentials(rp_id_hash: Optional[bytes] = None) -> List[Credential]:
     creds = []  # type: List[Credential]
-    for i in range(
-        _RESIDENT_CREDENTIAL_START_KEY,
-        _RESIDENT_CREDENTIAL_START_KEY + _MAX_RESIDENT_CREDENTIALS,
-    ):
-        stored_cred_data = common._get(common._APP_FIDO2, i)
-        if stored_cred_data is None:
-            continue
-
-        stored_rp_id_hash = stored_cred_data[:32]
-        stored_cred_id = stored_cred_data[32:]
-
-        if rp_id_hash is not None and rp_id_hash != stored_rp_id_hash:
-            # Stored credential is not for this RP ID.
-            continue
-
-        stored_cred = Fido2Credential.from_cred_id(stored_cred_id, stored_rp_id_hash)
-        if stored_cred is not None:
-            creds.append(stored_cred)
-
+    for i in range(_MAX_RESIDENT_CREDENTIALS):
+        cred = get_resident_credential(i, rp_id_hash)
+        if cred is not None:
+            creds.append(cred)
     return creds
 
 
+def get_resident_credential(
+    index: int, rp_id_hash: Optional[bytes] = None
+) -> Optional[Credential]:
+    if not (0 <= index < _MAX_RESIDENT_CREDENTIALS):
+        return None
+
+    stored_cred_data = common.get(
+        common.APP_FIDO2, index + _RESIDENT_CREDENTIAL_START_KEY
+    )
+    if stored_cred_data is None:
+        return None
+
+    stored_rp_id_hash = stored_cred_data[:32]
+    stored_cred_id = stored_cred_data[32:]
+
+    if rp_id_hash is not None and rp_id_hash != stored_rp_id_hash:
+        # Stored credential is not for this RP ID.
+        return None
+
+    stored_cred = Fido2Credential.from_cred_id(stored_cred_id, stored_rp_id_hash)
+    if stored_cred is None:
+        return None
+
+    stored_cred.index = index
+    return stored_cred
+
+
 def store_resident_credential(cred: Fido2Credential) -> bool:
     slot = None
-    for i in range(
-        _RESIDENT_CREDENTIAL_START_KEY,
-        _RESIDENT_CREDENTIAL_START_KEY + _MAX_RESIDENT_CREDENTIALS,
-    ):
-        stored_cred_data = common._get(common._APP_FIDO2, i)
+    for i in range(_MAX_RESIDENT_CREDENTIALS):
+        stored_cred_data = common.get(
+            common.APP_FIDO2, i + _RESIDENT_CREDENTIAL_START_KEY
+        )
         if stored_cred_data is None:
             if slot is None:
                 slot = i
@@ -66,13 +77,21 @@ def store_resident_credential(cred: Fido2Credential) -> bool:
     if slot is None:
         return False
 
-    common._set(common._APP_FIDO2, slot, cred.rp_id_hash + cred.id)
+    common.set(
+        common.APP_FIDO2,
+        slot + _RESIDENT_CREDENTIAL_START_KEY,
+        cred.rp_id_hash + cred.id,
+    )
     return True
 
 
 def erase_resident_credentials() -> None:
-    for i in range(
-        _RESIDENT_CREDENTIAL_START_KEY,
-        _RESIDENT_CREDENTIAL_START_KEY + _MAX_RESIDENT_CREDENTIALS,
-    ):
-        common._delete(common._APP_FIDO2, i)
+    for i in range(_MAX_RESIDENT_CREDENTIALS):
+        common.delete(common.APP_FIDO2, i + _RESIDENT_CREDENTIAL_START_KEY)
+
+
+def erase_resident_credential(index: int) -> bool:
+    if not (0 <= index < _MAX_RESIDENT_CREDENTIALS):
+        return False
+    common.delete(common.APP_FIDO2, index + _RESIDENT_CREDENTIAL_START_KEY)
+    return True

core/src/apps/webauthn/__init__.py

@@ -3,11 +3,12 @@ import ustruct
 import utime
 from micropython import const
 
-from trezor import config, io, log, loop, ui, utils, workflow
+from trezor import config, io, log, loop, ui, utils, wire, workflow
 from trezor.crypto import aes, der, hashlib, hmac, random
 from trezor.crypto.curve import nist256p1
+from trezor.messages import MessageType
 from trezor.ui.confirm import CONFIRMED, Confirm, ConfirmPageable, Pageable
-from trezor.ui.text import Text, text_center_trim_left, text_center_trim_right
+from trezor.ui.text import Text
 
 from apps.common import cbor, storage
 from apps.common.storage.webauthn import (
@@ -15,6 +16,7 @@ from apps.common.storage.webauthn import (
     get_resident_credentials,
     store_resident_credential,
 )
+from apps.webauthn.confirm import ConfirmContent, ConfirmInfo
 from apps.webauthn.credential import Credential, Fido2Credential, U2fCredential
 
 if __debug__:
@@ -464,6 +466,19 @@ def send_cmd_sync(cmd: Cmd, iface: io.HID) -> None:
 
 
 def boot(iface: io.HID) -> None:
+    wire.add(
+        MessageType.WebAuthnListResidentCredentials,
+        __name__,
+        "list_resident_credentials",
+    )
+    wire.add(
+        MessageType.WebAuthnAddResidentCredential, __name__, "add_resident_credential"
+    )
+    wire.add(
+        MessageType.WebAuthnRemoveResidentCredential,
+        __name__,
+        "remove_resident_credential",
+    )
     loop.schedule(handle_reports(iface))
 
 
@@ -526,64 +541,6 @@ async def confirm(*args: Any, **kwargs: Any) -> bool:
         return await dialog is CONFIRMED
 
 
-class ConfirmInfo:
-    def __init__(self) -> None:
-        self.app_icon = None  # type: Optional[bytes]
-
-    def get_header(self) -> Optional[str]:
-        return None
-
-    def app_name(self) -> str:
-        raise NotImplementedError
-
-    def account_name(self) -> Optional[str]:
-        return None
-
-    def load_icon(self, rp_id_hash: bytes) -> None:
-        from trezor import res
-        from apps.webauthn import knownapps
-
-        try:
-            namepart = knownapps.knownapps[rp_id_hash].lower().replace(" ", "_")
-            icon = res.load("apps/webauthn/res/icon_%s.toif" % namepart)
-        except Exception as e:
-            icon = res.load("apps/webauthn/res/icon_webauthn.toif")
-            if __debug__:
-                log.exception(__name__, e)
-        self.app_icon = icon
-
-
-class ConfirmContent(ui.Component):
-    def __init__(self, info: ConfirmInfo) -> None:
-        self.info = info
-        self.repaint = True
-
-    def on_render(self) -> None:
-        if self.repaint:
-            header = self.info.get_header()
-
-            if header is None or self.info.app_icon is None:
-                return
-            ui.header(header, ui.ICON_DEFAULT, ui.GREEN, ui.BG, ui.GREEN)
-            ui.display.image((ui.WIDTH - 64) // 2, 48, self.info.app_icon)
-
-            app_name = self.info.app_name()
-            account_name = self.info.account_name()
-
-            # Dummy requests usually have some text as both app_name and account_name,
-            # in that case show the text only once.
-            if account_name is not None:
-                if app_name != account_name:
-                    text_center_trim_left(ui.WIDTH // 2, 140, app_name)
-                    text_center_trim_right(ui.WIDTH // 2, 172, account_name)
-                else:
-                    text_center_trim_right(ui.WIDTH // 2, 156, account_name)
-            else:
-                text_center_trim_left(ui.WIDTH // 2, 156, app_name)
-
-            self.repaint = False
-
-
 class State:
     def __init__(self, cid: int, iface: io.HID) -> None:
         self.cid = cid

core/src/apps/webauthn/add_resident_credential.py

@@ -0,0 +1,54 @@
+from trezor import ui, wire
+from trezor.messages.Success import Success
+from trezor.messages.WebAuthnAddResidentCredential import WebAuthnAddResidentCredential
+from trezor.ui.text import Text
+
+from apps.common.confirm import require_confirm
+from apps.common.storage.webauthn import store_resident_credential
+from apps.webauthn.confirm import ConfirmContent, ConfirmInfo
+from apps.webauthn.credential import Fido2Credential
+
+if False:
+    from typing import Optional
+
+
+class ConfirmAddCredential(ConfirmInfo):
+    def __init__(self, cred: Fido2Credential):
+        self._cred = cred
+        self.load_icon(cred.rp_id_hash)
+
+    def get_header(self) -> str:
+        return "Import credential"
+
+    def app_name(self) -> str:
+        return self._cred.app_name()
+
+    def account_name(self) -> Optional[str]:
+        return self._cred.account_name()
+
+
+async def add_resident_credential(
+    ctx: wire.Context, msg: WebAuthnAddResidentCredential
+) -> Success:
+    if not msg.credential_id:
+        raise wire.ProcessError("Missing credential ID parameter.")
+
+    cred = Fido2Credential.from_cred_id(msg.credential_id, None)
+    if cred is None:
+        text = Text("Import credential", ui.ICON_WRONG, ui.RED)
+        text.normal(
+            "The credential you are",
+            "trying to import does",
+            "not belong to this",
+            "authenticator.",
+        )
+        await require_confirm(ctx, text, confirm=None)
+        raise wire.ActionCancelled("Cancelled")
+
+    content = ConfirmContent(ConfirmAddCredential(cred))
+    await require_confirm(ctx, content)
+
+    if store_resident_credential(cred):
+        return Success(message="Credential added")
+    else:
+        raise wire.ProcessError("Internal credential storage is full.")

core/src/apps/webauthn/confirm.py

@@ -0,0 +1,62 @@
+from trezor import log, ui
+from trezor.ui.text import text_center_trim_left, text_center_trim_right
+
+if False:
+    from typing import Optional
+
+
+class ConfirmInfo:
+    def __init__(self) -> None:
+        self.app_icon = None  # type: Optional[bytes]
+
+    def get_header(self) -> str:
+        raise NotImplementedError
+
+    def app_name(self) -> str:
+        raise NotImplementedError
+
+    def account_name(self) -> Optional[str]:
+        return None
+
+    def load_icon(self, rp_id_hash: bytes) -> None:
+        from trezor import res
+        from apps.webauthn import knownapps
+
+        try:
+            namepart = knownapps.knownapps[rp_id_hash].lower().replace(" ", "_")
+            icon = res.load("apps/webauthn/res/icon_%s.toif" % namepart)
+        except Exception as e:
+            icon = res.load("apps/webauthn/res/icon_webauthn.toif")
+            if __debug__:
+                log.exception(__name__, e)
+        self.app_icon = icon
+
+
+class ConfirmContent(ui.Component):
+    def __init__(self, info: ConfirmInfo) -> None:
+        self.info = info
+        self.repaint = True
+
+    def on_render(self) -> None:
+        if self.repaint:
+            header = self.info.get_header()
+            ui.header(header, ui.ICON_DEFAULT, ui.GREEN, ui.BG, ui.GREEN)
+
+            if self.info.app_icon is not None:
+                ui.display.image((ui.WIDTH - 64) // 2, 48, self.info.app_icon)
+
+            app_name = self.info.app_name()
+            account_name = self.info.account_name()
+
+            # Dummy requests usually have some text as both app_name and account_name,
+            # in that case show the text only once.
+            if account_name is not None:
+                if app_name != account_name:
+                    text_center_trim_left(ui.WIDTH // 2, 140, app_name)
+                    text_center_trim_right(ui.WIDTH // 2, 172, account_name)
+                else:
+                    text_center_trim_right(ui.WIDTH // 2, 156, account_name)
+            else:
+                text_center_trim_left(ui.WIDTH // 2, 156, app_name)
+
+            self.repaint = False

core/src/apps/webauthn/credential.py

@@ -30,6 +30,7 @@ _U2F_KEY_PATH = const(0x80553246)
 
 class Credential:
     def __init__(self) -> None:
+        self.index = None  # type Optional[int]
         self.id = b""  # type: bytes
         self.rp_id = ""  # type: str
         self.rp_id_hash = b""  # type: bytes
@@ -104,7 +105,9 @@ class Fido2Credential(Credential):
         self.id = _CRED_ID_VERSION + iv + ciphertext + tag
 
     @staticmethod
-    def from_cred_id(cred_id: bytes, rp_id_hash: bytes) -> Optional["Fido2Credential"]:
+    def from_cred_id(
+        cred_id: bytes, rp_id_hash: Optional[bytes]
+    ) -> Optional["Fido2Credential"]:
         if len(cred_id) < _CRED_ID_MIN_LENGTH or cred_id[0:4] != _CRED_ID_VERSION:
             return None
 
@@ -114,6 +117,16 @@ class Fido2Credential(Credential):
         iv = cred_id[4:16]
         ciphertext = cred_id[16:-16]
         tag = cred_id[-16:]
+
+        if rp_id_hash is None:
+            ctx = chacha20poly1305(key, iv)
+            data = ctx.decrypt(ciphertext)
+            try:
+                rp_id = cbor.decode(data)[_CRED_ID_RP_ID]
+            except Exception:
+                return None
+            rp_id_hash = hashlib.sha256(rp_id).digest()
+
         ctx = chacha20poly1305(key, iv)
         ctx.auth(rp_id_hash)
         data = ctx.decrypt(ciphertext)

core/src/apps/webauthn/list_resident_credentials.py

@@ -0,0 +1,38 @@
+from trezor import wire
+from trezor.messages.WebAuthnCredential import WebAuthnCredential
+from trezor.messages.WebAuthnCredentials import WebAuthnCredentials
+from trezor.messages.WebAuthnListResidentCredentials import (
+    WebAuthnListResidentCredentials,
+)
+from trezor.ui.text import Text
+
+from apps.common.confirm import require_confirm
+from apps.common.storage.webauthn import get_resident_credentials
+
+
+async def list_resident_credentials(
+    ctx: wire.Context, msg: WebAuthnListResidentCredentials
+) -> WebAuthnCredentials:
+    text = Text("List credentials")
+    text.normal(
+        "Do you want to export",
+        "information about the",
+        "resident credentials",
+        "stored on this device?",
+    )
+    await require_confirm(ctx, text)
+    creds = [
+        WebAuthnCredential(
+            index=cred.index,
+            id=cred.id,
+            rp_id=cred.rp_id,
+            rp_name=cred.rp_name,
+            user_id=cred.user_id,
+            user_name=cred.user_name,
+            user_display_name=cred.user_display_name,
+            creation_time=cred._creation_time,
+            hmac_secret=cred.hmac_secret,
+        )
+        for cred in get_resident_credentials()
+    ]
+    return WebAuthnCredentials(creds)

core/src/apps/webauthn/remove_resident_credential.py

@@ -0,0 +1,48 @@
+from trezor import wire
+from trezor.messages.Success import Success
+from trezor.messages.WebAuthnRemoveResidentCredential import (
+    WebAuthnRemoveResidentCredential,
+)
+
+from apps.common.confirm import require_confirm
+from apps.common.storage.webauthn import (
+    erase_resident_credential,
+    get_resident_credential,
+)
+from apps.webauthn.confirm import ConfirmContent, ConfirmInfo
+from apps.webauthn.credential import Fido2Credential
+
+if False:
+    from typing import Optional
+
+
+class ConfirmRemoveCredential(ConfirmInfo):
+    def __init__(self, cred: Fido2Credential):
+        self._cred = cred
+        self.load_icon(cred.rp_id_hash)
+
+    def get_header(self) -> str:
+        return "Remove credential"
+
+    def app_name(self) -> str:
+        return self._cred.app_name()
+
+    def account_name(self) -> Optional[str]:
+        return self._cred.account_name()
+
+
+async def remove_resident_credential(
+    ctx: wire.Context, msg: WebAuthnRemoveResidentCredential
+) -> Success:
+    if msg.index is None:
+        raise wire.ProcessError("Missing credential index parameter.")
+
+    cred = get_resident_credential(msg.index)
+    if cred is None:
+        raise wire.ProcessError("Invalid credential index.")
+
+    content = ConfirmContent(ConfirmRemoveCredential(cred))
+    await require_confirm(ctx, content)
+
+    erase_resident_credential(msg.index)
+    return Success(message="Credential removed")