Plan Windows metadata targets from filesystem policy

codex-rs/core/src/exec.rs

@@ -95,7 +95,8 @@ pub struct ExecParams {
     pub arg0: Option<String>,
 }
 
-/// Resolved filesystem overrides for the Windows sandbox backends.
+/// Layer: Windows adapter layer. Resolved filesystem overrides for the Windows
+/// sandbox backends.
 ///
 /// The unelevated restricted-token backend only consumes extra deny-write
 /// carveouts on top of the legacy `WorkspaceWrite` allow set. The elevated
@@ -109,6 +110,24 @@ pub(crate) struct WindowsSandboxFilesystemOverrides {
     pub(crate) read_roots_include_platform_defaults: bool,
     pub(crate) write_roots_override: Option<Vec<PathBuf>>,
     pub(crate) additional_deny_write_paths: Vec<AbsolutePathBuf>,
+    pub(crate) protected_metadata_targets: Vec<WindowsProtectedMetadataTarget>,
+}
+
+/// Layer: Windows adapter layer. This is the Windows projection of
+/// `WritableRoot::protected_metadata_names` from `FileSystemSandboxPolicy`.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub(crate) struct WindowsProtectedMetadataTarget {
+    pub(crate) path: AbsolutePathBuf,
+    pub(crate) mode: WindowsProtectedMetadataMode,
+}
+
+/// Layer: Windows adapter layer. The enforcement layer needs to know why a
+/// protected metadata path is absent instead of treating every missing path as
+/// an existing filesystem object.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub(crate) enum WindowsProtectedMetadataMode {
+    ExistingDeny,
+    MissingCreationMonitor,
 }
 
 fn windows_sandbox_uses_elevated_backend(
@@ -1131,7 +1150,9 @@ pub(crate) fn resolve_windows_restricted_token_filesystem_overrides(
         }
     }
 
-    if additional_deny_write_paths.is_empty() {
+    let protected_metadata_targets = windows_protected_metadata_targets(&split_writable_roots)?;
+
+    if additional_deny_write_paths.is_empty() && protected_metadata_targets.is_empty() {
         return Ok(None);
     }
 
@@ -1143,6 +1164,7 @@ pub(crate) fn resolve_windows_restricted_token_filesystem_overrides(
             .into_iter()
             .map(|path| AbsolutePathBuf::from_absolute_path(path).map_err(|err| err.to_string()))
             .collect::<std::result::Result<_, _>>()?,
+        protected_metadata_targets,
     }))
 }
 
@@ -1263,9 +1285,12 @@ pub(crate) fn resolve_windows_elevated_filesystem_overrides(
         Vec::new()
     };
 
+    let protected_metadata_targets = windows_protected_metadata_targets(&split_writable_roots)?;
+
     if read_roots_override.is_none()
         && write_roots_override.is_none()
         && additional_deny_write_paths.is_empty()
+        && protected_metadata_targets.is_empty()
     {
         return Ok(None);
     }
@@ -1276,9 +1301,36 @@ pub(crate) fn resolve_windows_elevated_filesystem_overrides(
         read_roots_override,
         write_roots_override,
         additional_deny_write_paths,
+        protected_metadata_targets,
     }))
 }
 
+fn windows_protected_metadata_targets(
+    writable_roots: &[codex_protocol::protocol::WritableRoot],
+) -> std::result::Result<Vec<WindowsProtectedMetadataTarget>, String> {
+    let mut targets = BTreeSet::new();
+    for writable_root in writable_roots {
+        for metadata_name in &writable_root.protected_metadata_names {
+            let path =
+                normalize_windows_override_path(writable_root.root.join(metadata_name).as_path())?;
+            let path = AbsolutePathBuf::from_absolute_path(path).map_err(|err| err.to_string())?;
+            targets.insert(WindowsProtectedMetadataTarget {
+                mode: windows_protected_metadata_mode(&path),
+                path,
+            });
+        }
+    }
+    Ok(targets.into_iter().collect())
+}
+
+fn windows_protected_metadata_mode(path: &AbsolutePathBuf) -> WindowsProtectedMetadataMode {
+    if std::fs::symlink_metadata(path.as_path()).is_ok() {
+        return WindowsProtectedMetadataMode::ExistingDeny;
+    }
+
+    WindowsProtectedMetadataMode::MissingCreationMonitor
+}
+
 fn has_reopened_writable_descendant(
     writable_roots: &[codex_protocol::protocol::WritableRoot],
 ) -> bool {

codex-rs/core/src/exec_tests.rs

@@ -663,6 +663,20 @@ fn windows_restricted_token_supports_full_read_split_write_read_carveouts() {
             read_roots_include_platform_defaults: false,
             write_roots_override: None,
             additional_deny_write_paths: expected_deny_write_paths,
+            protected_metadata_targets: vec![
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".agents"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".codex"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".git"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+            ],
         }))
     );
 }
@@ -700,6 +714,7 @@ fn windows_elevated_supports_split_restricted_read_roots() {
             read_roots_include_platform_defaults: false,
             write_roots_override: None,
             additional_deny_write_paths: vec![],
+            protected_metadata_targets: vec![],
         }))
     );
 }
@@ -707,6 +722,9 @@ fn windows_elevated_supports_split_restricted_read_roots() {
 #[test]
 fn windows_elevated_supports_split_write_read_carveouts() {
     let temp_dir = tempfile::TempDir::new().expect("tempdir");
+    let expected_root = dunce::canonicalize(temp_dir.path())
+        .expect("canonical temp dir")
+        .abs();
     let docs = temp_dir.path().join("docs");
     std::fs::create_dir_all(&docs).expect("create docs");
     let expected_docs = dunce::canonicalize(&docs).expect("canonical docs");
@@ -757,6 +775,146 @@ fn windows_elevated_supports_split_write_read_carveouts() {
                 codex_utils_absolute_path::AbsolutePathBuf::from_absolute_path(expected_docs)
                     .expect("absolute docs"),
             ],
+            protected_metadata_targets: vec![
+                WindowsProtectedMetadataTarget {
+                    path: expected_root.join(".agents"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: expected_root.join(".codex"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: expected_root.join(".git"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+            ],
+        }))
+    );
+}
+
+#[test]
+fn windows_metadata_plan_marks_existing_metadata_for_deny() {
+    let temp_dir = tempfile::TempDir::new().expect("tempdir");
+    let cwd = dunce::canonicalize(temp_dir.path())
+        .expect("canonical temp dir")
+        .abs();
+    std::fs::create_dir_all(cwd.join(".git").as_path()).expect("create .git");
+    let policy = SandboxPolicy::WorkspaceWrite {
+        writable_roots: vec![],
+        network_access: false,
+        exclude_tmpdir_env_var: true,
+        exclude_slash_tmp: true,
+    };
+    let file_system_policy = FileSystemSandboxPolicy::restricted(vec![
+        codex_protocol::permissions::FileSystemSandboxEntry {
+            path: codex_protocol::permissions::FileSystemPath::Special {
+                value: codex_protocol::permissions::FileSystemSpecialPath::Root,
+            },
+            access: codex_protocol::permissions::FileSystemAccessMode::Read,
+        },
+        codex_protocol::permissions::FileSystemSandboxEntry {
+            path: codex_protocol::permissions::FileSystemPath::Special {
+                value: codex_protocol::permissions::FileSystemSpecialPath::project_roots(
+                    /*subpath*/ None,
+                ),
+            },
+            access: codex_protocol::permissions::FileSystemAccessMode::Write,
+        },
+    ]);
+
+    assert_eq!(
+        resolve_windows_elevated_filesystem_overrides(
+            SandboxType::WindowsRestrictedToken,
+            &policy,
+            &file_system_policy,
+            NetworkSandboxPolicy::Restricted,
+            &cwd,
+            /*use_windows_elevated_backend*/ true,
+        ),
+        Ok(Some(WindowsSandboxFilesystemOverrides {
+            read_roots_override: None,
+            read_roots_include_platform_defaults: false,
+            write_roots_override: None,
+            additional_deny_write_paths: vec![],
+            protected_metadata_targets: vec![
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".agents"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".codex"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".git"),
+                    mode: WindowsProtectedMetadataMode::ExistingDeny,
+                },
+            ],
+        }))
+    );
+}
+
+#[test]
+fn windows_metadata_plan_does_not_materialize_nested_missing_git() {
+    let temp_dir = tempfile::TempDir::new().expect("tempdir");
+    let repo = dunce::canonicalize(temp_dir.path())
+        .expect("canonical temp dir")
+        .abs();
+    std::fs::create_dir_all(repo.join(".git").as_path()).expect("create parent .git");
+    let cwd = repo.join("child");
+    std::fs::create_dir_all(cwd.as_path()).expect("create child workspace");
+    let policy = SandboxPolicy::WorkspaceWrite {
+        writable_roots: vec![],
+        network_access: false,
+        exclude_tmpdir_env_var: true,
+        exclude_slash_tmp: true,
+    };
+    let file_system_policy = FileSystemSandboxPolicy::restricted(vec![
+        codex_protocol::permissions::FileSystemSandboxEntry {
+            path: codex_protocol::permissions::FileSystemPath::Special {
+                value: codex_protocol::permissions::FileSystemSpecialPath::Root,
+            },
+            access: codex_protocol::permissions::FileSystemAccessMode::Read,
+        },
+        codex_protocol::permissions::FileSystemSandboxEntry {
+            path: codex_protocol::permissions::FileSystemPath::Special {
+                value: codex_protocol::permissions::FileSystemSpecialPath::project_roots(
+                    /*subpath*/ None,
+                ),
+            },
+            access: codex_protocol::permissions::FileSystemAccessMode::Write,
+        },
+    ]);
+
+    assert_eq!(
+        resolve_windows_elevated_filesystem_overrides(
+            SandboxType::WindowsRestrictedToken,
+            &policy,
+            &file_system_policy,
+            NetworkSandboxPolicy::Restricted,
+            &cwd,
+            /*use_windows_elevated_backend*/ true,
+        ),
+        Ok(Some(WindowsSandboxFilesystemOverrides {
+            read_roots_override: None,
+            read_roots_include_platform_defaults: false,
+            write_roots_override: None,
+            additional_deny_write_paths: vec![],
+            protected_metadata_targets: vec![
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".agents"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".codex"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+                WindowsProtectedMetadataTarget {
+                    path: cwd.join(".git"),
+                    mode: WindowsProtectedMetadataMode::MissingCreationMonitor,
+                },
+            ],
         }))
     );
 }

codex-rs/windows-sandbox-rs/src/lib.rs

@@ -26,6 +26,7 @@ windows_modules!(
     path_normalization,
     policy,
     process,
+    protected_metadata,
     token,
     wfp,
     wfp_setup,
@@ -173,6 +174,10 @@ pub use session::spawn_windows_sandbox_session_elevated;
 #[cfg(target_os = "windows")]
 pub use session::spawn_windows_sandbox_session_legacy;
 #[cfg(target_os = "windows")]
+pub use setup::ProtectedMetadataMode;
+#[cfg(target_os = "windows")]
+pub use setup::ProtectedMetadataTarget;
+#[cfg(target_os = "windows")]
 pub use setup::SETUP_VERSION;
 #[cfg(target_os = "windows")]
 pub use setup::SandboxSetupRequest;

codex-rs/windows-sandbox-rs/src/protected_metadata.rs

@@ -0,0 +1,174 @@
+#![allow(dead_code)]
+
+use crate::setup::ProtectedMetadataMode;
+use crate::setup::ProtectedMetadataTarget;
+use anyhow::Context;
+use anyhow::Result;
+use std::fs::Metadata;
+use std::io;
+use std::os::windows::fs::FileTypeExt;
+use std::os::windows::fs::MetadataExt;
+use std::path::Path;
+use std::path::PathBuf;
+use windows_sys::Win32::Storage::FileSystem::FILE_ATTRIBUTE_REPARSE_POINT;
+
+/// Layer: Windows enforcement layer. Existing metadata objects can be protected
+/// with ACLs; missing names are monitored and removed if the sandbox creates
+/// them.
+#[derive(Debug)]
+pub(crate) struct ProtectedMetadataGuard {
+    deny_paths: Vec<PathBuf>,
+    monitored_paths: Vec<PathBuf>,
+}
+
+impl ProtectedMetadataGuard {
+    pub(crate) fn deny_paths(&self) -> impl Iterator<Item = &PathBuf> {
+        self.deny_paths.iter()
+    }
+
+    pub(crate) fn cleanup_created_monitored_paths(&self) -> Result<Vec<PathBuf>> {
+        let mut removed = Vec::new();
+        for path in &self.monitored_paths {
+            let Some(existing_path) = existing_metadata_path(path)? else {
+                continue;
+            };
+            remove_metadata_path(&existing_path)
+                .with_context(|| format!("failed to remove protected metadata {}", path.display()))?;
+            removed.push(existing_path);
+        }
+        Ok(removed)
+    }
+}
+
+pub(crate) fn prepare_protected_metadata_targets(
+    targets: &[ProtectedMetadataTarget],
+) -> ProtectedMetadataGuard {
+    let mut deny_paths = Vec::new();
+    let mut monitored_paths = Vec::new();
+    for target in targets {
+        match target.mode {
+            ProtectedMetadataMode::ExistingDeny => {
+                deny_paths.extend(protected_metadata_existing_deny_paths(&target.path));
+            }
+            ProtectedMetadataMode::MissingCreationMonitor => {
+                monitored_paths.push(target.path.clone());
+            }
+        }
+    }
+    ProtectedMetadataGuard {
+        deny_paths,
+        monitored_paths,
+    }
+}
+
+pub fn protected_metadata_existing_deny_paths(path: &Path) -> Vec<PathBuf> {
+    if std::fs::symlink_metadata(path).is_ok() {
+        vec![path.to_path_buf()]
+    } else {
+        Vec::new()
+    }
+}
+
+fn existing_metadata_path(path: &Path) -> Result<Option<PathBuf>> {
+    match std::fs::symlink_metadata(path) {
+        Ok(_) => return Ok(Some(path.to_path_buf())),
+        Err(err) if err.kind() == io::ErrorKind::NotFound => {}
+        Err(err) => {
+            return Err(err)
+                .with_context(|| format!("failed to inspect protected metadata {}", path.display()));
+        }
+    }
+
+    let Some(parent) = path.parent() else {
+        return Ok(None);
+    };
+    let Some(expected_name) = path.file_name().and_then(|name| name.to_str()) else {
+        return Ok(None);
+    };
+    let entries = match std::fs::read_dir(parent) {
+        Ok(entries) => entries,
+        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(None),
+        Err(err) => {
+            return Err(err)
+                .with_context(|| format!("failed to scan protected metadata parent {}", parent.display()));
+        }
+    };
+
+    for entry in entries {
+        let entry = entry.with_context(|| {
+            format!(
+                "failed to read protected metadata parent entry {}",
+                parent.display()
+            )
+        })?;
+        if entry
+            .file_name()
+            .to_str()
+            .is_some_and(|name| name.eq_ignore_ascii_case(expected_name))
+        {
+            return Ok(Some(entry.path()));
+        }
+    }
+    Ok(None)
+}
+
+fn remove_metadata_path(path: &Path) -> Result<()> {
+    let metadata = match std::fs::symlink_metadata(path) {
+        Ok(metadata) => metadata,
+        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(()),
+        Err(err) => {
+            return Err(err)
+                .with_context(|| format!("failed to inspect protected metadata {}", path.display()));
+        }
+    };
+    let file_type = metadata.file_type();
+    if is_directory_reparse_point(&metadata) || file_type.is_symlink_dir() {
+        std::fs::remove_dir(path)
+            .with_context(|| format!("failed to remove protected metadata {}", path.display()))?;
+    } else if file_type.is_symlink_file() {
+        std::fs::remove_file(path)
+            .with_context(|| format!("failed to remove protected metadata {}", path.display()))?;
+    } else if metadata.is_dir() {
+        std::fs::remove_dir_all(path)
+            .with_context(|| format!("failed to remove protected metadata {}", path.display()))?;
+    } else {
+        std::fs::remove_file(path)
+            .with_context(|| format!("failed to remove protected metadata {}", path.display()))?;
+    }
+    Ok(())
+}
+
+fn is_directory_reparse_point(metadata: &Metadata) -> bool {
+    metadata.is_dir() && (metadata.file_attributes() & FILE_ATTRIBUTE_REPARSE_POINT) != 0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::setup::ProtectedMetadataMode;
+    use crate::setup::ProtectedMetadataTarget;
+
+    #[test]
+    fn cleanup_created_monitored_paths_removes_case_variant() {
+        let temp_dir = tempfile::TempDir::new().expect("tempdir");
+        let target = temp_dir.path().join(".git");
+        let created = temp_dir.path().join(".GIT");
+        std::fs::create_dir_all(&created).expect("create metadata");
+        let guard = prepare_protected_metadata_targets(&[ProtectedMetadataTarget {
+            path: target.clone(),
+            mode: ProtectedMetadataMode::MissingCreationMonitor,
+        }]);
+
+        let removed = guard.cleanup_created_monitored_paths().expect("cleanup");
+        assert_eq!(removed.len(), 1);
+        assert!(
+            removed[0]
+                .file_name()
+                .is_some_and(|name| name.eq_ignore_ascii_case(".git")),
+            "removed path should be a .git case variant: {}",
+            removed[0].display()
+        );
+        assert!(!target.exists());
+        assert!(!created.exists());
+    }
+}

codex-rs/windows-sandbox-rs/src/setup_orchestrator.rs

@@ -99,6 +99,23 @@ pub struct SetupRootOverrides {
     pub deny_write_paths: Option<Vec<PathBuf>>,
 }
 
+/// Layer: Windows enforcement request boundary. These targets are projected by
+/// the adapter layer before they reach the setup helper.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ProtectedMetadataTarget {
+    pub path: PathBuf,
+    pub mode: ProtectedMetadataMode,
+}
+
+/// Layer: Windows enforcement request boundary. The helper must distinguish
+/// existing metadata objects from missing names that need create monitoring.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum ProtectedMetadataMode {
+    ExistingDeny,
+    MissingCreationMonitor,
+}
+
 pub fn run_setup_refresh(
     policy: &SandboxPolicy,
     policy_cwd: &Path,