Require fresh State Anchor absence before lease release

crates/lazaret-host-coordinator/src/bootstrap.rs

@@ -26,7 +26,10 @@ use crate::lifecycle::{
     SessionLifecycleAdapter,
 };
 use crate::network::NetworkCoordinator;
-use crate::runtime::{AwaitingAttachedRunsc, CommittedSandboxRuntime, SandboxCoordinator};
+use crate::runtime::{
+    AwaitingAttachedRunsc, CommittedSandboxRuntime, SandboxCoordinator,
+    StateAnchorAbsenceObservation,
+};
 use crate::state_anchor::{StateAnchorCoordinator, StateAnchorReleaseAuthority};
 
 #[derive(Debug)]
@@ -80,6 +83,7 @@ pub struct ProductionLifecycleAdapter<'a> {
     runtime: Option<CommittedSandboxRuntime>,
     state_anchor_mount: Option<MountIdentity>,
     state_anchor_release: Option<StateAnchorReleaseAuthority>,
+    state_anchor_absence: Option<StateAnchorAbsenceObservation>,
 }
 
 pub type ProductionHostCoordinatorLifecycle<'store, 'resources> = HostCoordinatorLifecycle<
@@ -175,6 +179,7 @@ impl<'a> ProductionLifecycleAdapter<'a> {
                 runtime: None,
                 state_anchor_mount: None,
                 state_anchor_release: None,
+                state_anchor_absence: None,
             },
             ProductionSessionRegistry { registry },
         )
@@ -409,18 +414,26 @@ impl<'a> ProductionLifecycleAdapter<'a> {
                 )
                 .map_err(failure)?,
         );
-        self.runtime
+        let runtime = self
+            .runtime
             .as_mut()
-            .ok_or_else(|| ProductionLifecycleError("committed runtime is absent".into()))?
+            .ok_or_else(|| ProductionLifecycleError("committed runtime is absent".into()))?;
-            .unmount_state_anchor(
+        let release = self
-                self.state_anchor_release
+            .state_anchor_release
-                    .as_ref()
+            .as_ref()
-                    .ok_or_else(|| {
+            .ok_or_else(|| ProductionLifecycleError("State Anchor release is absent".into()))?;
-                        ProductionLifecycleError("State Anchor release is absent".into())
+        runtime
-                    })?
+            .unmount_state_anchor(release.mount())
-                    .mount(),
-            )
             .map_err(failure)?;
+        self.state_anchor_absence = Some(
+            runtime
+                .observe_state_anchor_absence(
+                    release.user_namespace(),
+                    release.mount_namespace(),
+                    release.mount(),
+                )
+                .map_err(failure)?,
+        );
         self.state_anchor_mount = None;
         Ok(())
     }
@@ -428,11 +441,44 @@ impl<'a> ProductionLifecycleAdapter<'a> {
     fn release_prepared_lower(&mut self) -> Result<(), ProductionLifecycleError> {
         let release = self
             .state_anchor_release
-            .take()
+            .as_ref()
             .ok_or_else(|| ProductionLifecycleError("State Anchor release is absent".into()))?;
-        self.state_anchor()
+        let first_observation = self.state_anchor_absence.ok_or_else(|| {
-            .complete_release_after_unmount(&release, self.plan.state_anchor_layout)
+            ProductionLifecycleError("State Anchor absence evidence is absent".into())
-            .map_err(failure)
+        })?;
+        let runtime = self
+            .runtime
+            .as_mut()
+            .ok_or_else(|| ProductionLifecycleError("committed runtime is absent".into()))?;
+        let coordinator = StateAnchorCoordinator::new(&self.plan.store, self.plan.catalog);
+        coordinator
+            .complete_release_after_unmount(
+                release,
+                self.plan.state_anchor_layout,
+                first_observation,
+                || {
+                    runtime
+                        .observe_state_anchor_absence(
+                            release.user_namespace(),
+                            release.mount_namespace(),
+                            release.mount(),
+                        )
+                        .map_err(|error| {
+                            crate::state_anchor::StateAnchorCoordinatorError::InvalidState(
+                                match error {
+                                    crate::runtime::SandboxCoordinatorError::InvalidState(
+                                        detail,
+                                    ) => detail,
+                                    _ => "Runtime Supervisor absence observation failed",
+                                },
+                            )
+                        })
+                },
+            )
+            .map_err(failure)?;
+        self.state_anchor_release = None;
+        self.state_anchor_absence = None;
+        Ok(())
     }
 
     fn graceful_exit(&mut self) -> Result<(), ProductionLifecycleError> {

crates/lazaret-host-coordinator/src/runtime.rs

@@ -30,6 +30,14 @@ use crate::network::{NetworkCoordinator, NetworkCoordinatorError};
 
 const SUPERVISOR_EXIT_TIMEOUT: Duration = Duration::from_secs(5);
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct StateAnchorAbsenceObservation {
+    pub user_namespace: NamespaceIdentity,
+    pub mount_namespace: NamespaceIdentity,
+    pub mount: MountIdentity,
+    pub observed: MountIdentity,
+}
+
 #[derive(Debug)]
 pub enum SandboxCoordinatorError {
     Store(DomainStoreError),
@@ -967,6 +975,45 @@ impl CommittedSandboxRuntime {
         }
     }
 
+    /// Requests a fresh namespace-local observation of exact State Anchor absence.
+    ///
+    /// # Errors
+    /// Refuses an RS refusal, echoed mount, mismatched authority, or channel failure.
+    pub fn observe_state_anchor_absence(
+        &mut self,
+        user_namespace: NamespaceIdentity,
+        mount_namespace: NamespaceIdentity,
+        mount: MountIdentity,
+    ) -> Result<StateAnchorAbsenceObservation, SandboxCoordinatorError> {
+        self.control
+            .observe_state_anchor_absence(user_namespace, mount_namespace, mount)?;
+        match self.control.receive()? {
+            SupervisorEvent::StateAnchorAbsenceObserved {
+                user_namespace: observed_user_namespace,
+                mount_namespace: observed_mount_namespace,
+                mount: observed_mount,
+                observed,
+            } if observed_user_namespace == user_namespace
+                && observed_mount_namespace == mount_namespace
+                && observed_mount == mount
+                && observed != mount =>
+            {
+                Ok(StateAnchorAbsenceObservation {
+                    user_namespace: observed_user_namespace,
+                    mount_namespace: observed_mount_namespace,
+                    mount: observed_mount,
+                    observed,
+                })
+            }
+            SupervisorEvent::Refused(detail) => {
+                Err(SandboxCoordinatorError::Io(io::Error::other(detail)))
+            }
+            _ => Err(SandboxCoordinatorError::InvalidState(
+                "Runtime Supervisor did not provide exact State Anchor absence evidence",
+            )),
+        }
+    }
+
     /// Gracefully exits and reaps the resource-empty exact Runtime Supervisor.
     ///
     /// # Errors

crates/lazaret-host-coordinator/src/state_anchor.rs

@@ -15,6 +15,7 @@ use lazaret_state_anchor::{StateAnchorError, StateAnchorLayout, VerifiedStateAnc
 use lazaret_storage_catalog::{Catalog, CatalogError};
 
 use crate::domain_store::{DomainStoreError, DomainStoreMutation, HostCoordinatorDomainStore};
+use crate::runtime::StateAnchorAbsenceObservation;
 
 #[derive(Debug)]
 pub enum StateAnchorCoordinatorError {
@@ -367,11 +368,17 @@ impl<'a> StateAnchorCoordinator<'a> {
     ///
     /// # Errors
     /// Refuses a stale authority, any remaining mount, or release-evidence mismatch.
-    pub fn complete_release_after_unmount(
+    pub fn complete_release_after_unmount<Observe>(
         &self,
         authority: &StateAnchorReleaseAuthority,
         layout: &StateAnchorLayout<'_>,
-    ) -> Result<(), StateAnchorCoordinatorError> {
+        first_observation: StateAnchorAbsenceObservation,
+        mut observe_again: Observe,
+    ) -> Result<(), StateAnchorCoordinatorError>
+    where
+        Observe: FnMut() -> Result<StateAnchorAbsenceObservation, StateAnchorCoordinatorError>,
+    {
+        require_absence_observation(authority, first_observation)?;
         let expected_layout = layout.ownership_intent(authority.lease.prepared_artifact_id);
         let expected_merged = expected_layout.merged_path.as_ref().ok_or(
             StateAnchorCoordinatorError::InvalidState("State Anchor merged path is absent"),
@@ -407,7 +414,7 @@ impl<'a> StateAnchorCoordinator<'a> {
                 ));
             }
         }
-        self.release_catalog_lease_if_present(authority)?;
+        self.release_catalog_lease_if_present(authority, &mut observe_again)?;
         self.domain_store
             .apply(&[DomainStoreMutation::CleanParticipantAfterAbsence(
                 clean_participant(authority.generation_id, ParticipantRole::PreparedLower)?,
@@ -528,10 +535,14 @@ impl<'a> StateAnchorCoordinator<'a> {
         }
     }
 
-    fn release_catalog_lease_if_present(
+    fn release_catalog_lease_if_present<Observe>(
         &self,
         authority: &StateAnchorReleaseAuthority,
-    ) -> Result<(), StateAnchorCoordinatorError> {
+        observe_again: &mut Observe,
+    ) -> Result<(), StateAnchorCoordinatorError>
+    where
+        Observe: FnMut() -> Result<StateAnchorAbsenceObservation, StateAnchorCoordinatorError>,
+    {
         let snapshot = self.catalog.snapshot()?;
         let generation_lease = snapshot.artifact_leases.iter().find(|lease| {
             lease.domain_id == authority.lease.domain_id
@@ -570,12 +581,33 @@ impl<'a> StateAnchorCoordinator<'a> {
                     "Domain release evidence is not committed",
                 )));
             }
+            let observation =
+                observe_again().map_err(|error| CatalogError::Io(io::Error::other(error)))?;
+            require_absence_observation(authority, observation)
+                .map_err(|error| CatalogError::Io(io::Error::other(error)))?;
             Ok(())
         })?;
         Ok(())
     }
 }
 
+fn require_absence_observation(
+    authority: &StateAnchorReleaseAuthority,
+    observation: StateAnchorAbsenceObservation,
+) -> Result<(), StateAnchorCoordinatorError> {
+    if observation.user_namespace == authority.user_namespace
+        && observation.mount_namespace == authority.mount_namespace
+        && observation.mount == authority.mount
+        && observation.observed != authority.mount
+    {
+        Ok(())
+    } else {
+        Err(StateAnchorCoordinatorError::InvalidState(
+            "State Anchor absence evidence mismatches release authority",
+        ))
+    }
+}
+
 fn release_authority(
     domain: &lazaret_core::records::Domain,
     anchor: &Participant,

crates/lazaret-host-coordinator/src/state_anchor/tests.rs

@@ -182,6 +182,44 @@ fn durable_phases_resume_release_without_collapsing_lease_order() {
         ParticipantState::ReleaseIntent,
     );
     assert_eq!(catalog.snapshot().unwrap().artifact_leases, vec![lease]);
+    let valid = absence_observation(&authority);
+    let invalid_observations = [
+        StateAnchorAbsenceObservation {
+            observed: authority.mount(),
+            ..valid
+        },
+        StateAnchorAbsenceObservation {
+            user_namespace: NamespaceIdentity {
+                device: DeviceId::new(193),
+                inode: InodeId::new(194),
+            },
+            ..valid
+        },
+        StateAnchorAbsenceObservation {
+            mount_namespace: NamespaceIdentity {
+                device: DeviceId::new(195),
+                inode: InodeId::new(196),
+            },
+            ..valid
+        },
+        StateAnchorAbsenceObservation {
+            mount: valid.observed,
+            ..valid
+        },
+    ];
+    for invalid in invalid_observations {
+        assert!(
+            coordinator
+                .complete_release_after_unmount(&authority, &layout, invalid, || Ok(valid))
+                .is_err()
+        );
+        assert_states(
+            &domain_store,
+            ParticipantState::LeaseHeld,
+            ParticipantState::ReleaseIntent,
+        );
+        assert_eq!(catalog.snapshot().unwrap().artifact_leases, vec![lease]);
+    }
     let snapshot = domain_store.snapshot().unwrap();
     let prepared = role(
         &snapshot.participants,
@@ -197,9 +235,42 @@ fn durable_phases_resume_release_without_collapsing_lease_order() {
             DomainStoreMutation::PutParticipant(prepared_release_intent(prepared).unwrap()),
         ])
         .unwrap();
+    for invalid in invalid_observations {
+        assert!(
+            coordinator
+                .complete_release_after_unmount(&authority, &layout, valid, || Ok(invalid))
+                .is_err()
+        );
+        assert_eq!(catalog.snapshot().unwrap().artifact_leases, vec![lease]);
+    }
+    assert!(
+        coordinator
+            .complete_release_after_unmount(&authority, &layout, valid, || {
+                Err(StateAnchorCoordinatorError::InvalidState(
+                    "State Anchor absence evidence is unreadable",
+                ))
+            })
+            .is_err()
+    );
+    assert_eq!(catalog.snapshot().unwrap().artifact_leases, vec![lease]);
+    assert!(
+        coordinator
+            .complete_release_after_unmount(&authority, &layout, valid, || {
+                Err(StateAnchorCoordinatorError::InvalidState(
+                    "second State Anchor observation was skipped",
+                ))
+            })
+            .is_err()
+    );
+    assert_eq!(catalog.snapshot().unwrap().artifact_leases, vec![lease]);
+    let mut observations = 0;
     coordinator
-        .complete_release_after_unmount(&authority, &layout)
+        .complete_release_after_unmount(&authority, &layout, valid, || {
+            observations += 1;
+            Ok(valid)
+        })
         .unwrap();
+    assert_eq!(observations, 1);
     assert_states(
         &domain_store,
         ParticipantState::Clean,
@@ -208,6 +279,19 @@ fn durable_phases_resume_release_without_collapsing_lease_order() {
     assert!(catalog.snapshot().unwrap().artifact_leases.is_empty());
 }
 
+fn absence_observation(authority: &StateAnchorReleaseAuthority) -> StateAnchorAbsenceObservation {
+    StateAnchorAbsenceObservation {
+        user_namespace: authority.user_namespace(),
+        mount_namespace: authority.mount_namespace(),
+        mount: authority.mount(),
+        observed: MountIdentity {
+            mount_id: MountId::new(authority.mount().mount_id.get() + 1),
+            device: authority.mount().device,
+            inode: authority.mount().inode,
+        },
+    }
+}
+
 #[test]
 fn acquisition_resumes_after_prepared_intent_reopen() {
     let fixture = AcquisitionFixture::new(17);

crates/lazaret-runtime-supervisor/src/supervision.rs

@@ -9,7 +9,7 @@ use std::time::{Duration, Instant};
 use lazaret_core::codec::{decode, encode};
 use lazaret_core::identity::{
     ConfigurationFingerprint, CoordinatorId, DerivedPolicyDigest, DomainId, GenerationId,
-    NetworkSidecarId,
+    MountIdentity, NamespaceIdentity, NetworkSidecarId,
 };
 use lazaret_core::network::CanonicalDerivedNetworkPolicy;
 use lazaret_core::records::{
@@ -23,7 +23,8 @@ use lazaret_linux::process::{
     child_broker, current_process_identity,
 };
 use lazaret_state_anchor::{
-    RuntimeStateAnchorAuthority, RuntimeStateAnchorMount, StateAnchorLaunchAuthority,
+    RuntimeStateAnchorAbsenceAuthority, RuntimeStateAnchorAuthority, RuntimeStateAnchorInherited,
+    RuntimeStateAnchorMount, StateAnchorLaunchAuthority,
 };
 use rustix::event::{PollFd, PollFlags, Timespec, poll};
 use rustix::fs::{MemfdFlags, memfd_create};
@@ -86,6 +87,12 @@ pub enum SupervisorEvent {
     StateAnchorUnmounted {
         mount: lazaret_core::identity::MountIdentity,
     },
+    StateAnchorAbsenceObserved {
+        user_namespace: NamespaceIdentity,
+        mount_namespace: NamespaceIdentity,
+        mount: MountIdentity,
+        observed: MountIdentity,
+    },
     Exited,
     AttachedRunscExited,
     Stopped,
@@ -106,6 +113,11 @@ enum CoordinatorMessage {
     StopSandbox,
     StopSidecar,
     UnmountStateAnchor,
+    ObserveStateAnchorAbsence {
+        user_namespace: NamespaceIdentity,
+        mount_namespace: NamespaceIdentity,
+        mount: MountIdentity,
+    },
     Exit,
     Stop,
 }
@@ -225,6 +237,24 @@ impl CoordinatorChannel {
         send_message(&self.descriptor, &CoordinatorMessage::UnmountStateAnchor)
     }
 
+    /// # Errors
+    /// Returns an error when exact namespace-local absence observation cannot be requested.
+    pub fn observe_state_anchor_absence(
+        &self,
+        user_namespace: NamespaceIdentity,
+        mount_namespace: NamespaceIdentity,
+        mount: MountIdentity,
+    ) -> io::Result<()> {
+        send_message(
+            &self.descriptor,
+            &CoordinatorMessage::ObserveStateAnchorAbsence {
+                user_namespace,
+                mount_namespace,
+                mount,
+            },
+        )
+    }
+
     /// # Errors
     /// Returns an error when graceful Runtime Supervisor exit cannot be requested.
     pub fn exit(&self) -> io::Result<()> {
@@ -657,8 +687,19 @@ fn run_supervisor(arguments: &RuntimeArguments) -> io::Result<()> {
     let control = std::io::stdout();
     let parent = current_process_identity()?;
     let mut state_anchor = prepare_state_anchor(arguments, parent, namespaces, &control)?;
-    let result = run_supervisor_with_state(arguments, parent, &control, &mut state_anchor);
+    let mut state_anchor_absence = None;
-    let cleanup = state_anchor.take().map(RuntimeStateAnchorMount::unmount);
+    let result = run_supervisor_with_state(
+        arguments,
+        parent,
+        &control,
+        namespaces,
+        &mut state_anchor,
+        &mut state_anchor_absence,
+    );
+    let cleanup = state_anchor
+        .take()
+        .map(RuntimeStateAnchorMount::unmount)
+        .map(|result| result.map(drop));
     match (result, cleanup) {
         (Err(error), Some(Err(cleanup))) => Err(io::Error::new(
             error.kind(),
@@ -688,17 +729,17 @@ fn prepare_state_anchor(
             "Runtime Supervisor received no State Anchor mount command",
         ));
     }
-    let authority = RuntimeStateAnchorAuthority::from_inherited(
+    let authority = RuntimeStateAnchorAuthority::from_inherited(RuntimeStateAnchorInherited {
-        state.lower_fd,
+        lower_fd: state.lower_fd,
-        &state.lower_label,
+        lower_label: &state.lower_label,
-        state.persistent_root_fd,
+        persistent_root_fd: state.persistent_root_fd,
-        state.persistent_anchor_fd,
+        persistent_anchor_fd: state.persistent_anchor_fd,
-        &state.persistent_anchor_label,
+        persistent_anchor_label: &state.persistent_anchor_label,
-        state.runtime_root_fd,
+        runtime_root_fd: state.runtime_root_fd,
-        state.runtime_anchor_fd,
+        runtime_anchor_fd: state.runtime_anchor_fd,
-        &state.runtime_anchor_label,
+        runtime_anchor_label: &state.runtime_anchor_label,
-        state.expected_lower,
+        expected_lower: state.expected_lower,
-    )
+    })
     .map_err(io::Error::other)?;
     let ownership = ProcessOwnershipContext {
         slot: HostProcessOwnershipSlot::StateAnchorDaemon,
@@ -742,7 +783,9 @@ fn run_supervisor_with_state(
     arguments: &RuntimeArguments,
     parent: lazaret_core::identity::PidfsProcessIdentityV1,
     control: &std::io::Stdout,
+    namespaces: (NamespaceIdentity, NamespaceIdentity),
     state_anchor: &mut Option<RuntimeStateAnchorMount>,
+    state_anchor_absence: &mut Option<RuntimeStateAnchorAbsenceAuthority>,
 ) -> io::Result<()> {
     if arguments.state_anchor.is_some() {
         let message: CoordinatorMessage = receive_message(control)?;
@@ -827,7 +870,15 @@ fn run_supervisor_with_state(
             io::Error::other("sandbox commit acknowledgment was not received"),
         );
     }
-    supervise(control, process, network, state_anchor, &delete)
+    supervise(
+        control,
+        process,
+        network,
+        namespaces,
+        state_anchor,
+        state_anchor_absence,
+        &delete,
+    )
 }
 
 fn prepare_runtime_network(
@@ -983,10 +1034,17 @@ fn supervise(
     control: &std::io::Stdout,
     process: RetainedProcess,
     mut network: Option<PreparedNetwork>,
+    namespaces: (NamespaceIdentity, NamespaceIdentity),
     state_anchor: &mut Option<RuntimeStateAnchorMount>,
+    state_anchor_absence: &mut Option<RuntimeStateAnchorAbsenceAuthority>,
     delete: &TargetCommand,
 ) -> io::Result<()> {
     let mut process = Some(process);
+    let mut state_anchor = StateAnchorSupervision {
+        namespaces,
+        mount: state_anchor,
+        absence: state_anchor_absence,
+    };
     loop {
         let exited = match process
             .as_ref()
@@ -1059,7 +1117,7 @@ fn supervise(
                 &message,
                 &mut process,
                 &mut network,
-                state_anchor,
+                &mut state_anchor,
                 delete,
             ) {
                 Ok(true) => return Ok(()),
@@ -1070,12 +1128,18 @@ fn supervise(
     }
 }
 
+struct StateAnchorSupervision<'a> {
+    namespaces: (NamespaceIdentity, NamespaceIdentity),
+    mount: &'a mut Option<RuntimeStateAnchorMount>,
+    absence: &'a mut Option<RuntimeStateAnchorAbsenceAuthority>,
+}
+
 fn handle_supervisor_message(
     control: &std::io::Stdout,
     message: &CoordinatorMessage,
     process: &mut Option<RetainedProcess>,
     network: &mut Option<PreparedNetwork>,
-    state_anchor: &mut Option<RuntimeStateAnchorMount>,
+    state_anchor: &mut StateAnchorSupervision<'_>,
     delete: &TargetCommand,
 ) -> io::Result<bool> {
     match message {
@@ -1102,25 +1166,17 @@ fn handle_supervisor_message(
             stop_network(network.take())?;
             send_message(control, &SupervisorEvent::SidecarStopped)?;
         }
-        CoordinatorMessage::UnmountStateAnchor => {
+        CoordinatorMessage::UnmountStateAnchor
-            if process.is_some() || network.is_some() {
+        | CoordinatorMessage::ObserveStateAnchorAbsence { .. } => {
-                return Err(io::Error::other(
+            handle_state_anchor_message(
-                    "State Anchor unmount preceded runtime resource stop",
+                control,
-                ));
+                message,
-            }
+                process.is_some() || network.is_some(),
-            let mount = state_anchor
+                state_anchor,
-                .as_ref()
+            )?;
-                .ok_or_else(|| io::Error::other("State Anchor is absent"))?
-                .mount_identity();
-            state_anchor
-                .take()
-                .ok_or_else(|| io::Error::other("State Anchor is absent"))?
-                .unmount()
-                .map_err(io::Error::other)?;
-            send_message(control, &SupervisorEvent::StateAnchorUnmounted { mount })?;
         }
         CoordinatorMessage::Exit => {
-            if process.is_some() || network.is_some() || state_anchor.is_some() {
+            if process.is_some() || network.is_some() || state_anchor.mount.is_some() {
                 return Err(io::Error::other(
                     "Runtime Supervisor exit preceded resource cleanup",
                 ));
@@ -1150,6 +1206,70 @@ fn handle_supervisor_message(
     Ok(false)
 }
 
+fn handle_state_anchor_message(
+    control: &std::io::Stdout,
+    message: &CoordinatorMessage,
+    runtime_resources_present: bool,
+    state: &mut StateAnchorSupervision<'_>,
+) -> io::Result<()> {
+    match message {
+        CoordinatorMessage::UnmountStateAnchor => {
+            if runtime_resources_present {
+                return Err(io::Error::other(
+                    "State Anchor unmount preceded runtime resource stop",
+                ));
+            }
+            let mount = state
+                .mount
+                .as_ref()
+                .ok_or_else(|| io::Error::other("State Anchor is absent"))?
+                .mount_identity();
+            let absence = state
+                .mount
+                .take()
+                .ok_or_else(|| io::Error::other("State Anchor is absent"))?
+                .unmount()
+                .map_err(io::Error::other)?;
+            *state.absence = Some(absence);
+            send_message(control, &SupervisorEvent::StateAnchorUnmounted { mount })
+        }
+        CoordinatorMessage::ObserveStateAnchorAbsence {
+            user_namespace,
+            mount_namespace,
+            mount,
+        } => {
+            if (*user_namespace, *mount_namespace) != state.namespaces {
+                return send_message(
+                    control,
+                    &SupervisorEvent::Refused(
+                        "State Anchor absence request namespace authority mismatched".into(),
+                    ),
+                );
+            }
+            match state.absence.as_ref().map_or_else(
+                || {
+                    Err(lazaret_state_anchor::StateAnchorError::InvalidLayout(
+                        "State Anchor absence authority is absent",
+                    ))
+                },
+                |authority| authority.observe_absence(*mount),
+            ) {
+                Ok(observed) => send_message(
+                    control,
+                    &SupervisorEvent::StateAnchorAbsenceObserved {
+                        user_namespace: state.namespaces.0,
+                        mount_namespace: state.namespaces.1,
+                        mount: *mount,
+                        observed,
+                    },
+                ),
+                Err(error) => send_message(control, &SupervisorEvent::Refused(error.to_string())),
+            }
+        }
+        _ => Err(io::Error::other("message is not a State Anchor command")),
+    }
+}
+
 fn fail_active_runtime(
     process: Option<RetainedProcess>,
     network: Option<PreparedNetwork>,
@@ -1347,6 +1467,30 @@ mod tests {
             receive_message::<CoordinatorMessage>(&supervisor).unwrap(),
             CoordinatorMessage::UnmountStateAnchor
         );
+        let user_namespace = NamespaceIdentity {
+            device: lazaret_core::identity::DeviceId::new(11),
+            inode: lazaret_core::identity::InodeId::new(12),
+        };
+        let mount_namespace = NamespaceIdentity {
+            device: lazaret_core::identity::DeviceId::new(13),
+            inode: lazaret_core::identity::InodeId::new(14),
+        };
+        let mount = MountIdentity {
+            mount_id: lazaret_core::identity::MountId::new(15),
+            device: lazaret_core::identity::DeviceId::new(16),
+            inode: lazaret_core::identity::InodeId::new(17),
+        };
+        channel
+            .observe_state_anchor_absence(user_namespace, mount_namespace, mount)
+            .unwrap();
+        assert_eq!(
+            receive_message::<CoordinatorMessage>(&supervisor).unwrap(),
+            CoordinatorMessage::ObserveStateAnchorAbsence {
+                user_namespace,
+                mount_namespace,
+                mount,
+            }
+        );
         channel.exit().unwrap();
         assert_eq!(
             receive_message::<CoordinatorMessage>(&supervisor).unwrap(),

crates/lazaret-runtime-supervisor/tests/sandbox_builder.rs

@@ -11,7 +11,7 @@ use lazaret_core::identity::{ContainerId, DeviceId, InodeId, NamespaceIdentity};
 use lazaret_runtime_supervisor::sandbox::{
     CREDENTIALS_DESTINATION, ESCALATION_CLIENT_DESTINATION, HostTerminal,
     MAILBOX_REQUESTS_DESTINATION, MAILBOX_RESULTS_DESTINATION, NETWORK_NAMESPACE_PATH, RootProcess,
-    SANDBOX_INIT_DESTINATION, SandboxBuildErrorKind, SandboxBuildRequest,
+    SANDBOX_INIT_DESTINATION, SandboxBuildErrorKind, SandboxBuildRequest, SandboxBundle,
     TERMINFO_ROOT_DESTINATION, WORKSPACE_DESTINATION, build_sandbox_bundle,
     production_sandbox_layout, stage_host_terminal,
 };
@@ -312,7 +312,20 @@ fn deterministic_snapshot_has_only_private_namespaces_and_fixed_runtime_shape()
         }])
     );
 
-    assert_eq!(first.command().program(), OsStr::new("runsc"));
+    assert_runtime_command(&first, &fixture);
+    assert_eq!(
+        specification["root"]["path"],
+        fixture
+            .tree
+            .path()
+            .join("prepared-root")
+            .display()
+            .to_string()
+    );
+}
+
+fn assert_runtime_command(bundle: &SandboxBundle, fixture: &Fixture) {
+    assert_eq!(bundle.command().program(), OsStr::new("runsc"));
     let runtime_domain = String::from_utf8(
         fixture
             .configuration
@@ -323,7 +336,7 @@ fn deterministic_snapshot_has_only_private_namespaces_and_fixed_runtime_shape()
     )
     .unwrap();
     assert_eq!(
-        first
+        bundle
             .command()
             .arguments()
             .iter()
@@ -355,16 +368,7 @@ fn deterministic_snapshot_has_only_private_namespaces_and_fixed_runtime_shape()
             "11".repeat(32),
         ]
     );
-    assert_eq!(
+    assert!(!bundle.command().arguments().iter().any(|argument| {
-        specification["root"]["path"],
-        fixture
-            .tree
-            .path()
-            .join("prepared-root")
-            .display()
-            .to_string()
-    );
-    assert!(!first.command().arguments().iter().any(|argument| {
         matches!(
             argument.to_str(),
             Some("-detach" | "-console-socket" | "-c")

crates/lazaret-state-anchor/src/lib.rs

@@ -530,33 +530,39 @@ pub struct RuntimeStateAnchorAuthority {
     merged_descriptor: OwnedFd,
 }
 
+#[derive(Clone, Copy)]
+pub struct RuntimeStateAnchorInherited<'a> {
+    pub lower_fd: i32,
+    pub lower_label: &'a Path,
+    pub persistent_root_fd: i32,
+    pub persistent_anchor_fd: i32,
+    pub persistent_anchor_label: &'a Path,
+    pub runtime_root_fd: i32,
+    pub runtime_anchor_fd: i32,
+    pub runtime_anchor_label: &'a Path,
+    pub expected_lower: (u64, u64),
+}
+
 impl RuntimeStateAnchorAuthority {
     /// Reopens inherited authorities without falling back to ambient configured paths.
     ///
     /// # Errors
     /// Refuses missing, replaced, or incorrectly typed descriptors and fixed children.
     pub fn from_inherited(
-        lower_fd: i32,
+        inherited: RuntimeStateAnchorInherited<'_>,
-        lower_label: &Path,
-        persistent_root_fd: i32,
-        persistent_anchor_fd: i32,
-        persistent_anchor_label: &Path,
-        runtime_root_fd: i32,
-        runtime_anchor_fd: i32,
-        runtime_anchor_label: &Path,
-        expected_lower: (u64, u64),
     ) -> Result<Self, StateAnchorError> {
-        let retained_lower = reopen_inherited_directory(lower_fd)?;
+        let retained_lower = reopen_inherited_directory(inherited.lower_fd)?;
-        require_directory_descriptor_identity(&retained_lower, expected_lower)?;
+        require_directory_descriptor_identity(&retained_lower, inherited.expected_lower)?;
-        if !lower_label.is_absolute() {
+        if !inherited.lower_label.is_absolute() {
             return Err(StateAnchorError::InvalidLayout(
                 "prepared lower label is not absolute",
             ));
         }
-        let lower = open_exact_directory_path(lower_label, expected_lower)?;
+        let lower = open_exact_directory_path(inherited.lower_label, inherited.expected_lower)?;
-        let persistent_root = reopen_inherited_directory(persistent_root_fd)?;
+        let persistent_root = reopen_inherited_directory(inherited.persistent_root_fd)?;
-        let retained_persistent_anchor = reopen_inherited_directory(persistent_anchor_fd)?;
+        let retained_persistent_anchor =
-        if !persistent_anchor_label.is_absolute() {
+            reopen_inherited_directory(inherited.persistent_anchor_fd)?;
+        if !inherited.persistent_anchor_label.is_absolute() {
             return Err(StateAnchorError::InvalidLayout(
                 "persistent State Anchor label is not absolute",
             ));
@@ -570,12 +576,12 @@ impl RuntimeStateAnchorAuthority {
             (retained_persistent.st_dev, retained_persistent.st_ino),
         )?;
         let persistent_anchor = open_exact_directory_path(
-            persistent_anchor_label,
+            inherited.persistent_anchor_label,
             (retained_persistent.st_dev, retained_persistent.st_ino),
         )?;
-        let runtime_root = reopen_inherited_directory(runtime_root_fd)?;
+        let runtime_root = reopen_inherited_directory(inherited.runtime_root_fd)?;
-        let retained_runtime_anchor = reopen_inherited_directory(runtime_anchor_fd)?;
+        let retained_runtime_anchor = reopen_inherited_directory(inherited.runtime_anchor_fd)?;
-        if !runtime_anchor_label.is_absolute() {
+        if !inherited.runtime_anchor_label.is_absolute() {
             return Err(StateAnchorError::InvalidLayout(
                 "runtime State Anchor label is not absolute",
             ));
@@ -586,13 +592,15 @@ impl RuntimeStateAnchorAuthority {
             &confined_runtime_anchor,
             (retained.st_dev, retained.st_ino),
         )?;
-        let runtime_anchor =
+        let runtime_anchor = open_exact_directory_path(
-            open_exact_directory_path(runtime_anchor_label, (retained.st_dev, retained.st_ino))?;
+            inherited.runtime_anchor_label,
+            (retained.st_dev, retained.st_ino),
+        )?;
         for name in ["upper", "work"] {
             drop(open_directory(&persistent_anchor, Path::new(name))?);
         }
         let merged_descriptor = open_directory(&runtime_anchor, Path::new("merged"))?;
-        let merged_label = runtime_anchor_label.join("merged");
+        let merged_label = inherited.runtime_anchor_label.join("merged");
         Ok(Self {
             lower,
             persistent_anchor,
@@ -699,6 +707,32 @@ pub struct RuntimeStateAnchorMount {
     merged: OwnedFd,
 }
 
+pub struct RuntimeStateAnchorAbsenceAuthority {
+    runtime_anchor: OwnedFd,
+    mount: MountIdentity,
+}
+
+impl RuntimeStateAnchorAbsenceAuthority {
+    /// Reopens the exact runtime anchor to produce a fresh post-unmount observation.
+    ///
+    /// # Errors
+    /// Refuses an unreadable anchor or the continued presence of the retired mount.
+    pub fn observe_absence(
+        &self,
+        expected_mount: MountIdentity,
+    ) -> Result<MountIdentity, StateAnchorError> {
+        if expected_mount != self.mount {
+            return Err(StateAnchorError::OwnershipMismatch);
+        }
+        let observed = mount_identity(&open_directory(&self.runtime_anchor, Path::new("merged"))?)?;
+        if observed == self.mount {
+            Err(StateAnchorError::OwnershipMismatch)
+        } else {
+            Ok(observed)
+        }
+    }
+}
+
 impl RuntimeStateAnchorMount {
     #[must_use]
     pub const fn mount_identity(&self) -> MountIdentity {
@@ -756,7 +790,7 @@ impl RuntimeStateAnchorMount {
     ///
     /// # Errors
     /// Refuses mount replacement, unmount failure, or exact child cleanup failure.
-    pub fn unmount(self) -> Result<(), StateAnchorError> {
+    pub fn unmount(self) -> Result<RuntimeStateAnchorAbsenceAuthority, StateAnchorError> {
         let Self {
             authority,
             process,
@@ -777,7 +811,10 @@ impl RuntimeStateAnchorMount {
             return Err(StateAnchorError::OwnershipMismatch);
         }
         child_broker().reap(process)?;
-        Ok(())
+        Ok(RuntimeStateAnchorAbsenceAuthority {
+            runtime_anchor: authority.runtime_anchor,
+            mount,
+        })
     }
 }
 
@@ -1195,12 +1232,10 @@ fn append_fuse_option_path(target: &mut Vec<u8>, path: &Path) {
     }
 }
 
-#[allow(clippy::disallowed_methods, clippy::disallowed_types)]
 fn rootless_unmount(layout: &StateAnchorLayout<'_>) -> Result<(), StateAnchorError> {
     rootless_unmount_anchor(&layout.runtime_anchor)
 }
 
-#[allow(clippy::disallowed_methods, clippy::disallowed_types)]
 fn rootless_unmount_anchor(runtime_anchor: impl AsFd) -> Result<(), StateAnchorError> {
     let inherited_anchor = inherit_for_exec(runtime_anchor)?;
     let path = descriptor_child_path(&inherited_anchor, "merged");
@@ -1208,17 +1243,14 @@ fn rootless_unmount_anchor(runtime_anchor: impl AsFd) -> Result<(), StateAnchorE
 }
 
 fn rootless_unmount_path(path: &Path) -> Result<(), StateAnchorError> {
-    let status = std::process::Command::new("fusermount3")
+    child_broker()
-        .arg("-u")
+        .run_transient(
-        .arg(path)
+            &TargetCommand::new("fusermount3")
-        .status()?;
+                .argument("-u")
-    if status.success() {
+                .argument(path),
-        Ok(())
+        )
-    } else {
+        .map(drop)
-        Err(StateAnchorError::Io(io::Error::other(format!(
+        .map_err(StateAnchorError::from)
-            "fusermount3 exited with {status}"
-        ))))
-    }
 }
 
 fn require_mount_record(

crates/lazaret-state-anchor/tests/authority.rs

@@ -15,8 +15,8 @@ use lazaret_core::identity::{
 };
 use lazaret_core::records::{ArtifactState, PreparedArtifact};
 use lazaret_state_anchor::{
-    ProtectedRuntimeFiles, RuntimeStateAnchorAuthority, StateAnchorLaunchAuthority,
+    ProtectedRuntimeFiles, RuntimeStateAnchorAuthority, RuntimeStateAnchorInherited,
-    StateAnchorLayout,
+    StateAnchorLaunchAuthority, StateAnchorLayout,
 };
 
 static SEQUENCE: AtomicU64 = AtomicU64::new(0);
@@ -78,30 +78,12 @@ fn inherited_runtime_authority_accepts_only_the_exact_prepared_lower() {
     };
     let launch = StateAnchorLaunchAuthority::capture(&layout, &artifact).unwrap();
     let expected = launch.expected_lower();
-    RuntimeStateAnchorAuthority::from_inherited(
+    RuntimeStateAnchorAuthority::from_inherited(inherited(&launch, expected)).unwrap();
-        launch.lower_fd(),
-        launch.lower_label(),
-        launch.persistent_root_fd(),
-        launch.persistent_anchor_fd(),
-        launch.persistent_anchor_label(),
-        launch.runtime_root_fd(),
-        launch.runtime_anchor_fd(),
-        launch.runtime_anchor_label(),
-        expected,
-    )
-    .unwrap();
     assert!(
-        RuntimeStateAnchorAuthority::from_inherited(
+        RuntimeStateAnchorAuthority::from_inherited(inherited(
-            launch.lower_fd(),
+            &launch,
-            launch.lower_label(),
-            launch.persistent_root_fd(),
-            launch.persistent_anchor_fd(),
-            launch.persistent_anchor_label(),
-            launch.runtime_root_fd(),
-            launch.runtime_anchor_fd(),
-            launch.runtime_anchor_label(),
             (expected.0, expected.1 + 1),
-        )
+        ))
         .is_err()
     );
 }
@@ -150,18 +132,8 @@ fn namespace_local_rebound_refuses_a_replaced_state_anchor() {
     fs::create_dir(&anchor).unwrap();
 
     assert!(
-        RuntimeStateAnchorAuthority::from_inherited(
+        RuntimeStateAnchorAuthority::from_inherited(inherited(&launch, launch.expected_lower(),))
-            launch.lower_fd(),
+            .is_err()
-            launch.lower_label(),
-            launch.persistent_root_fd(),
-            launch.persistent_anchor_fd(),
-            launch.persistent_anchor_label(),
-            launch.runtime_root_fd(),
-            launch.runtime_anchor_fd(),
-            launch.runtime_anchor_label(),
-            launch.expected_lower(),
-        )
-        .is_err()
     );
 }
 
@@ -178,18 +150,8 @@ fn namespace_local_rebound_refuses_a_replaced_prepared_lower() {
     fs::create_dir(&lower).unwrap();
 
     assert!(
-        RuntimeStateAnchorAuthority::from_inherited(
+        RuntimeStateAnchorAuthority::from_inherited(inherited(&launch, launch.expected_lower(),))
-            launch.lower_fd(),
+            .is_err()
-            launch.lower_label(),
-            launch.persistent_root_fd(),
-            launch.persistent_anchor_fd(),
-            launch.persistent_anchor_label(),
-            launch.runtime_root_fd(),
-            launch.runtime_anchor_fd(),
-            launch.runtime_anchor_label(),
-            launch.expected_lower(),
-        )
-        .is_err()
     );
 }
 
@@ -207,18 +169,8 @@ fn namespace_local_rebound_refuses_a_replaced_persistent_anchor() {
     fs::create_dir(&anchor).unwrap();
 
     assert!(
-        RuntimeStateAnchorAuthority::from_inherited(
+        RuntimeStateAnchorAuthority::from_inherited(inherited(&launch, launch.expected_lower(),))
-            launch.lower_fd(),
+            .is_err()
-            launch.lower_label(),
-            launch.persistent_root_fd(),
-            launch.persistent_anchor_fd(),
-            launch.persistent_anchor_label(),
-            launch.runtime_root_fd(),
-            launch.runtime_anchor_fd(),
-            launch.runtime_anchor_label(),
-            launch.expected_lower(),
-        )
-        .is_err()
     );
 }
 
@@ -237,21 +189,28 @@ fn namespace_local_rebound_refuses_a_state_anchor_symlink() {
     std::os::unix::fs::symlink(&retained, &anchor).unwrap();
 
     assert!(
-        RuntimeStateAnchorAuthority::from_inherited(
+        RuntimeStateAnchorAuthority::from_inherited(inherited(&launch, launch.expected_lower(),))
-            launch.lower_fd(),
+            .is_err()
-            launch.lower_label(),
-            launch.persistent_root_fd(),
-            launch.persistent_anchor_fd(),
-            launch.persistent_anchor_label(),
-            launch.runtime_root_fd(),
-            launch.runtime_anchor_fd(),
-            launch.runtime_anchor_label(),
-            launch.expected_lower(),
-        )
-        .is_err()
     );
 }
 
+fn inherited(
+    launch: &StateAnchorLaunchAuthority,
+    expected_lower: (u64, u64),
+) -> RuntimeStateAnchorInherited<'_> {
+    RuntimeStateAnchorInherited {
+        lower_fd: launch.lower_fd(),
+        lower_label: launch.lower_label(),
+        persistent_root_fd: launch.persistent_root_fd(),
+        persistent_anchor_fd: launch.persistent_anchor_fd(),
+        persistent_anchor_label: launch.persistent_anchor_label(),
+        runtime_root_fd: launch.runtime_root_fd(),
+        runtime_anchor_fd: launch.runtime_anchor_fd(),
+        runtime_anchor_label: launch.runtime_anchor_label(),
+        expected_lower,
+    }
+}
+
 fn prepared_artifact(lower: &Path) -> PreparedArtifact {
     let metadata = lower.metadata().unwrap();
     PreparedArtifact {

crates/lazaret-state-anchor/tests/state-anchor-lifecycle.rs

@@ -19,9 +19,9 @@ use lazaret_linux::process::{
     ProcessOwnershipContext, current_process_identity, dispatch_private_process_role,
 };
 use lazaret_state_anchor::{
-    FuseOverlayfsMount, ProtectedRuntimeFiles, RuntimeStateAnchorAuthority, StateAnchorAcquisition,
+    FuseOverlayfsMount, ProtectedRuntimeFiles, RuntimeStateAnchorAuthority,
-    StateAnchorLaunchAuthority, StateAnchorLayout, StateAnchorSandboxView,
+    RuntimeStateAnchorInherited, StateAnchorAcquisition, StateAnchorLaunchAuthority,
-    unmount_after_coordinator_loss,
+    StateAnchorLayout, StateAnchorSandboxView, unmount_after_coordinator_loss,
 };
 use rustix::process::Signal;
 
@@ -80,18 +80,19 @@ fn run() -> io::Result<()> {
 
     let launch =
         StateAnchorLaunchAuthority::capture(&layout, &artifact).map_err(io::Error::other)?;
-    let runtime_authority = RuntimeStateAnchorAuthority::from_inherited(
+    let runtime_authority =
-        launch.lower_fd(),
+        RuntimeStateAnchorAuthority::from_inherited(RuntimeStateAnchorInherited {
-        launch.lower_label(),
+            lower_fd: launch.lower_fd(),
-        launch.persistent_root_fd(),
+            lower_label: launch.lower_label(),
-        launch.persistent_anchor_fd(),
+            persistent_root_fd: launch.persistent_root_fd(),
-        launch.persistent_anchor_label(),
+            persistent_anchor_fd: launch.persistent_anchor_fd(),
-        launch.runtime_root_fd(),
+            persistent_anchor_label: launch.persistent_anchor_label(),
-        launch.runtime_anchor_fd(),
+            runtime_root_fd: launch.runtime_root_fd(),
-        launch.runtime_anchor_label(),
+            runtime_anchor_fd: launch.runtime_anchor_fd(),
-        launch.expected_lower(),
+            runtime_anchor_label: launch.runtime_anchor_label(),
-    )
+            expected_lower: launch.expected_lower(),
-    .map_err(io::Error::other)?;
+        })
+        .map_err(io::Error::other)?;
     let expected = std::cell::Cell::new(None);
     let runtime_mount = runtime_authority
         .acquire(