Reject unsafe filesystem paths from the HACS manifest

[frenck]

Proposed change

The filename and persistent_directory values from hacs.json end up in filesystem paths ({temp_dir}/{filename} in both zip download paths, and {content.path.local}/{persistent_directory} during install). They were only validated as str, so a hostile manifest could point them outside the intended directory with values like ../../custom_components/evil and place files outside its category lane.

This adds a shared is_safe_relative_path() helper that rejects absolute paths and any .. segment (both slash styles), and applies it in two places:

• HACS_MANIFEST_JSON_SCHEMA: used by the HACS action, so default repository submissions with such values are rejected loudly at publish time.
• HacsManifest.from_dict: the single construction point for all runtime manifests (fetched hacs.json, custom repositories, storage restore). Unsafe values are dropped with a warning instead of raising, so a bad stored manifest can never break the startup restore.

Nested relative paths like sub/dir remain allowed, existing legitimate repositories are unaffected.

For completeness: the zip extraction paths themselves were checked and are not vulnerable to zip-slip, Python's zipfile.extractall sanitizes .. components and absolute member names. This change is about the manifest values, which bypass that sanitization because they are used to build paths directly.

Type of change

• Enhancement (hardening, non-breaking)

Checklist

• The code change is tested and works locally.
• Local tests pass.
• There is no commented out code in this PR.

[Copilot]

Pull request overview

This PR hardens HACS manifest handling by preventing repository-provided manifest fields (filename, persistent_directory) from being used to form unsafe filesystem paths that could escape intended directories.

Changes:

• Introduces is_safe_relative_path() and applies it to manifest path-like fields.
• Enforces safe-relative-path validation in the publish-time schema (HACS_MANIFEST_JSON_SCHEMA).
• Sanitizes unsafe values at runtime in HacsManifest.from_dict() (dropping them with a warning) and adds/extends tests covering the behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
custom_components/hacs/utils/path.py	Adds the shared safe-relative-path helper used to gate manifest-derived paths.
custom_components/hacs/utils/validate.py	Updates the HACS manifest JSON schema to validate filename/persistent_directory as safe relative paths.
custom_components/hacs/repositories/base.py	Applies runtime sanitization of filename/persistent_directory when constructing HacsManifest from a dict.
tests/utils/test_validate.py	Adds schema-level tests ensuring unsafe paths and non-strings are rejected.
tests/utils/test_path.py	Adds unit tests for is_safe_relative_path() behavior.
tests/repositories/test_hacs_manifest.py	Adds runtime tests verifying unsafe values are ignored (and safe ones retained) during from_dict().

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