unix socket auth

Author: mdevaev

kvmd/apps/__init__.py

@@ -360,6 +360,11 @@ def _get_config_scheme() -> dict:
                 "enabled": Option(True, type=valid_bool),
                 "expire":  Option(0,    type=valid_expire),
 
+                "usc": {
+                    "users":  Option([], type=valid_users_list),  # PiKVM username has a same regex as a UNIX username
+                    "groups": Option([], type=valid_users_list),  # groupname has a same regex as a username
+                },
+
                 "internal": {
                     "type":        Option("htpasswd"),
                     "force_users": Option([], type=valid_users_list),

kvmd/apps/kvmd/__init__.py

@@ -77,6 +77,8 @@ def main(argv: (list[str] | None)=None) -> None:
         auth_manager=AuthManager(
             enabled=config.auth.enabled,
             expire=config.auth.expire,
+            usc_users=config.auth.usc.users,
+            usc_groups=config.auth.usc.groups,
             unauth_paths=([] if config.prometheus.auth.enabled else ["/export/prometheus/metrics"]),
 
             int_type=config.auth.internal.type,

kvmd/apps/kvmd/api/auth.py

@@ -31,6 +31,7 @@
 from ....htserver import exposed_http
 from ....htserver import make_json_response
 from ....htserver import set_request_auth_info
+from ....htserver import get_request_unix_credentials
 
 from ....validators.auth import valid_user
 from ....validators.auth import valid_passwd
@@ -76,6 +77,14 @@ async def check_request_auth(auth_manager: AuthManager, exposed: HttpExposed, re
                 raise ForbiddenError()
             return
 
+        if exposed.allow_usc:
+            creds = get_request_unix_credentials(req)
+            if creds is not None:
+                user = auth_manager.check_unix_credentials(creds)  # type: ignore
+                if user:
+                    set_request_auth_info(req, f"{user}[{creds.uid}] (unix)")
+                    return
+
         raise UnauthorizedError()
 
 
@@ -85,7 +94,7 @@ def __init__(self, auth_manager: AuthManager) -> None:
 
     # =====
 
-    @exposed_http("POST", "/auth/login", auth_required=False)
+    @exposed_http("POST", "/auth/login", auth_required=False, allow_usc=False)
     async def __login_handler(self, req: Request) -> Response:
         if self.__auth_manager.is_auth_enabled():
             credentials = await req.post()
@@ -99,13 +108,14 @@ async def __login_handler(self, req: Request) -> Response:
             raise ForbiddenError()
         return make_json_response()
 
-    @exposed_http("POST", "/auth/logout")
+    @exposed_http("POST", "/auth/logout", allow_usc=False)
     async def __logout_handler(self, req: Request) -> Response:
         if self.__auth_manager.is_auth_enabled():
             token = valid_auth_token(req.cookies.get(_COOKIE_AUTH_TOKEN, ""))
             self.__auth_manager.logout(token)
         return make_json_response()
 
-    @exposed_http("GET", "/auth/check")
+    # XXX: This handle is used for access control so it should NEVER allow access by socket credentials
+    @exposed_http("GET", "/auth/check", allow_usc=False)
     async def __check_handler(self, _: Request) -> Response:
         return make_json_response()

kvmd/apps/kvmd/auth.py

@@ -20,6 +20,8 @@
 # ========================================================================== #
 
 
+import pwd
+import grp
 import dataclasses
 import time
 import datetime
@@ -35,6 +37,7 @@
 from ...plugins.auth import get_auth_service_class
 
 from ...htserver import HttpExposed
+from ...htserver import RequestUnixCredentials
 
 
 # =====
@@ -49,11 +52,13 @@ def __post_init__(self) -> None:
         assert self.expire_ts >= 0
 
 
-class AuthManager:  # pylint: disable=too-many-instance-attributes
+class AuthManager:  # pylint: disable=too-many-arguments,too-many-instance-attributes
     def __init__(
         self,
         enabled: bool,
         expire: int,
+        usc_users: list[str],
+        usc_groups: list[str],
         unauth_paths: list[str],
 
         int_type: str,
@@ -78,9 +83,15 @@ def __init__(
             logger.info("Maximum user session time is limited: %s",
                         self.__format_seconds(expire))
 
+        self.__usc_uids = self.__load_usc_uids(usc_users, usc_groups)
+        if self.__usc_uids:
+            logger.info("Unauth UNIX socket access is allowed for users: %s",
+                        list(self.__usc_uids.values()))
+
         self.__unauth_paths = frozenset(unauth_paths)  # To speed up
-        for path in self.__unauth_paths:
-            logger.warning("Authorization is disabled for API %r", path)
+        if self.__unauth_paths:
+            logger.info("Authorization is disabled for APIs: %s",
+                        list(self.__unauth_paths))
 
         self.__int_service: (BaseAuthService | None) = None
         if enabled:
@@ -244,3 +255,29 @@ async def cleanup(self) -> None:
             await self.__int_service.cleanup()
             if self.__ext_service:
                 await self.__ext_service.cleanup()
+
+    # =====
+
+    def __load_usc_uids(self, users: list[str], groups: list[str]) -> dict[int, str]:
+        uids: dict[int, str] = {}
+
+        pwds: dict[str, int] = {}
+        for pw in pwd.getpwall():
+            assert pw.pw_name == pw.pw_name.strip()
+            assert pw.pw_name
+            pwds[pw.pw_name] = pw.pw_uid
+            if pw.pw_name in users:
+                uids[pw.pw_uid] = pw.pw_name
+
+        for gr in grp.getgrall():
+            if gr.gr_name in groups:
+                for member in gr.gr_mem:
+                    if member in pwds:
+                        uid = pwds[member]
+                        uids[uid] = member
+
+        return uids
+
+    def check_unix_credentials(self, creds: RequestUnixCredentials) -> (str | None):
+        assert self.__enabled
+        return self.__usc_uids.get(creds.uid)

kvmd/htserver.py

@@ -22,6 +22,7 @@
 
 import os
 import socket
+import struct
 import asyncio
 import contextlib
 import dataclasses
@@ -83,21 +84,30 @@ class HttpExposed:
     method: str
     path: str
     auth_required: bool
+    allow_usc: bool
     handler: Callable
 
 
 _HTTP_EXPOSED = "_http_exposed"
 _HTTP_METHOD = "_http_method"
 _HTTP_PATH = "_http_path"
 _HTTP_AUTH_REQUIRED = "_http_auth_required"
+_HTTP_ALLOW_USC = "_http_allow_usc"
 
 
-def exposed_http(http_method: str, path: str, auth_required: bool=True) -> Callable:
+def exposed_http(
+    http_method: str,
+    path: str,
+    auth_required: bool=True,
+    allow_usc: bool=True,
+) -> Callable:
+
     def set_attrs(handler: Callable) -> Callable:
         setattr(handler, _HTTP_EXPOSED, True)
         setattr(handler, _HTTP_METHOD, http_method)
         setattr(handler, _HTTP_PATH, path)
         setattr(handler, _HTTP_AUTH_REQUIRED, auth_required)
+        setattr(handler, _HTTP_ALLOW_USC, allow_usc)
         return handler
     return set_attrs
 
@@ -108,6 +118,7 @@ def _get_exposed_http(obj: object) -> list[HttpExposed]:
             method=getattr(handler, _HTTP_METHOD),
             path=getattr(handler, _HTTP_PATH),
             auth_required=getattr(handler, _HTTP_AUTH_REQUIRED),
+            allow_usc=getattr(handler, _HTTP_ALLOW_USC),
             handler=handler,
         )
         for handler in [getattr(obj, name) for name in dir(obj)]
@@ -270,6 +281,34 @@ def set_request_auth_info(req: BaseRequest, info: str) -> None:
     setattr(req, _REQUEST_AUTH_INFO, info)
 
 
+@dataclasses.dataclass(frozen=True)
+class RequestUnixCredentials:
+    pid: int
+    uid: int
+    gid: int
+
+    def __post_init__(self) -> None:
+        assert self.pid > 0
+        assert self.uid >= 0
+        assert self.gid >= 0
+
+
+def get_request_unix_credentials(req: BaseRequest) -> (RequestUnixCredentials | None):
+    if req.transport is None:
+        return None
+    sock = req.transport.get_extra_info("socket")
+    if sock is None:
+        return None
+    try:
+        data = sock.getsockopt(socket.SOL_SOCKET, socket.SO_PEERCRED, struct.calcsize("iii"))
+    except Exception:
+        return None
+    (pid, uid, gid) = struct.unpack("iii", data)
+    if pid <= 0 or uid < 0 or gid < 0:
+        return None
+    return RequestUnixCredentials(pid=pid, uid=uid, gid=gid)
+
+
 # =====
 @dataclasses.dataclass(frozen=True)
 class WsSession:
@@ -314,13 +353,14 @@ def run(
 
         if unix_rm and os.path.exists(unix_path):
             os.remove(unix_path)
-        server_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-        server_socket.bind(unix_path)
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        sock.setsockopt(socket.SOL_SOCKET, socket.SO_PASSCRED, 1)
+        sock.bind(unix_path)
         if unix_mode:
             os.chmod(unix_path, unix_mode)
 
         run_app(
-            sock=server_socket,
+            sock=sock,
             app=self.__make_app(),
             shutdown_timeout=1,
             access_log_format=access_log_format,

testenv/linters/vulture-wl.py

@@ -83,3 +83,6 @@
 StorageContext.read_atx_cp_delays
 StorageContext.read_atx_cpl_delays
 StorageContext.read_atx_cr_delays
+
+RequestUnixCredentials.pid
+RequestUnixCredentials.gid

testenv/tests/apps/kvmd/test_auth.py

@@ -40,9 +40,9 @@
 
 
 # =====
-_E_AUTH = HttpExposed("GET", "/foo_auth", True, (lambda: None))
-_E_UNAUTH = HttpExposed("GET", "/bar_unauth", True, (lambda: None))
-_E_FREE = HttpExposed("GET", "/baz_free", False, (lambda: None))
+_E_AUTH = HttpExposed("GET", "/foo_auth", auth_required=True, allow_usc=True, handler=(lambda: None))
+_E_UNAUTH = HttpExposed("GET", "/bar_unauth", auth_required=True, allow_usc=True, handler=(lambda: None))
+_E_FREE = HttpExposed("GET", "/baz_free", auth_required=False, allow_usc=True, handler=(lambda: None))
 
 
 def _make_service_kwargs(path: str) -> dict:
@@ -62,6 +62,8 @@ async def _get_configured_manager(
     manager = AuthManager(
         enabled=True,
         expire=0,
+        usc_users=[],
+        usc_groups=[],
         unauth_paths=unauth_paths,
 
         int_type="htpasswd",
@@ -262,6 +264,8 @@ async def test_ok__disabled() -> None:
         manager = AuthManager(
             enabled=False,
             expire=0,
+            usc_users=[],
+            usc_groups=[],
             unauth_paths=[],
 
             int_type="foobar",