check hostid on Jail.start when hostid_strict_check is enabled

Author: gronke

libioc/Config/Jail/Defaults.py

@@ -56,6 +56,8 @@
     "host_hostuuid": None,
     "host_hostname": None,
     "host_domainname": None,
+    "hostid": None,
+    "hostid_strict_check": False,
     "devfs_ruleset": 4,
     "enforce_statfs": 2,
     "children_max": 0,

libioc/Host.py

@@ -55,6 +55,7 @@ class HostGenerator:
     _devfs: libioc.DevfsRules.DevfsRules
     _defaults: libioc.Resource.DefaultResource
     _defaults_initialized = False
+    __hostid: str
     releases_dataset: libzfs.ZFSDataset
     datasets: libioc.Datasets.Datasets
     distribution: _distribution_types
@@ -114,6 +115,19 @@ def _init_defaults(
                 zfs=self.zfs
             )
 
+    @property
+    def id(self) -> str:
+        """Return the hostid and memoize on first lookup."""
+        try:
+            return self.__hostid
+        except AttributeError:
+            pass
+
+        with open("/etc/hostid", "r") as f:
+            self.__hostid = f.read().strip()
+
+        return self.__hostid
+
     @property
     def defaults(self) -> 'libioc.Resource.DefaultResource':
         """Return the lazy-loaded defaults."""

libioc/Jail.py

@@ -466,6 +466,7 @@ def start(
         """
         self.require_jail_existing()
         self.require_jail_stopped()
+        self.require_jail_match_hostid()
 
         try:
             yield from self.config["resolver"].apply(
@@ -1430,6 +1431,8 @@ def _create_from_resource(
         if backend is not None:
             backend.setup(self.storage, resource)
 
+        self.config["hostid"] = self.host.id
+
         self._update_fstab()
         self.save()
 
@@ -2012,6 +2015,26 @@ def require_jail_is_template(self, log_errors: bool=True) -> None:
                 logger=(self.logger if log_errors else None)
             )
 
+    def require_jail_match_hostid(self, log_errors: bool=True) -> None:
+        """Raise JailIsTemplate exception if the jail is a template."""
+        if self.hostid_check_ok is False:
+            raise libioc.errors.JailHostIdMismatch(
+                jail=self,
+                host_hostid=self.host.id,
+                logger=(self.logger if log_errors else None)
+            )
+
+    @property
+    def hostid_check_ok(self) -> bool:
+        """Return true if the hostid check passes."""
+        if self.config["hostid_strict_check"] is False:
+            self.logger.spam("hostid_strict_check is disabled")
+            return True
+        jail_hostid = self.config["hostid"]
+        if (jail_hostid is None) or (jail_hostid == self.host.id):
+            return True
+        return False
+
     def require_storage_backend(self, log_errors: bool=True) -> None:
         """Raise if the jail was not initialized with a storage backend."""
         if self.storage_backend is None:

libioc/errors.py

@@ -461,6 +461,23 @@ def __init__(
         IocException.__init__(self, message=msg, logger=logger)
 
 
+class JailHostIdMismatch(JailException):
+    """Raised when attempting to start a jail with mismatching hostid."""
+
+    def __init__(
+        self,
+        host_hostid: str,
+        jail: 'libioc.Jail.JailGenerator',
+        logger: typing.Optional['libioc.Logger.Logger']=None
+    ) -> None:
+        jail_hostid = jail.config["hostid"]
+        msg = (
+            f"The jail hostid '{jail_hostid}' "
+            f"does not match the hosts hostid '{host_hostid}'"
+        )
+        JailException.__init__(self, message=msg, jail=jail, logger=logger)
+
+
 class JailConfigNotFound(IocException):
     """Raised when a jail is not configured."""