Fix: private dataset authorization bypass in shared dataset access checks (#14645)

### Related issues
Closes #14644

### What problem does this PR solve?

This PR fixes an authorization bug where datasets marked with
`permission = me` could still be accessed by other members of the same
tenant through APIs that relied on `KnowledgebaseService.accessible()`
or `DocumentService.accessible()`.

Before this change, those shared access helpers only checked tenant
membership and did not enforce the dataset's permission mode. As a
result, a non-owner who knew a private `dataset_id` could still reach
downstream document and chunk operations even though the dataset was
intended to be owner-only.

This change updates the central access checks so that:

- dataset owners always retain access
- joined tenant members only get access when the dataset permission is
`TEAM`
- private datasets with `permission = me` remain inaccessible to
non-owners
- document-level access follows the same dataset permission rules

The PR also adds regression coverage for private-vs-team dataset access
behavior.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

### Testing

- Added
`test/unit_test/api/db/services/test_dataset_access_permissions.py`
- Attempted to run: `python -m pytest
test\\unit_test\\api\\db\\services\\test_dataset_access_permissions.py
-q`
- Local execution in this workspace is currently blocked during test
collection because the environment is missing the `strenum` dependency

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: jony376 <jony376@gmail.com>
Co-authored-by: Wang Qi <wangq8@outlook.com>
Co-authored-by: d 🔹 <liusway405@gmail.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: Magicbook1108 <newyorkupperbay@gmail.com>
Co-authored-by: chanx <1243304602@qq.com>
Co-authored-by: sxxtony <166789813+sxxtony@users.noreply.github.com>
Co-authored-by: sxxtony <sxxtony@users.noreply.github.com>
Co-authored-by: Baki Burak Öğün <63836730+bakiburakogun@users.noreply.github.com>
Co-authored-by: bakiburakogun <bakiburakogun@users.noreply.github.com>
Co-authored-by: Panda Dev <56657208+pandadev66@users.noreply.github.com>
Co-authored-by: Haruko386 <tryeverypossible@163.com>
Co-authored-by: D2758695161 <13510221939@163.com>
Co-authored-by: Hunter <hunter@yitong.ai>
Co-authored-by: Lynn <lynn_inf@hotmail.com>
Co-authored-by: buua436 <sz_buua@foxmail.com>
Co-authored-by: web-dev0521 <jasonpette1783@gmail.com>
Co-authored-by: Tim Wang <38489718+wanghualoong@users.noreply.github.com>
Co-authored-by: wanghualoong <wanghualoong@gmail.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: qinling0210 <88864212+qinling0210@users.noreply.github.com>
Co-authored-by: dale053 <star05223@outlook.com>

test/unit_test/api/db/services/test_dataset_access_permissions.py

@@ -0,0 +1,119 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+import sys
+import types
+import warnings
+from types import SimpleNamespace
+
+# xgboost imports pkg_resources and emits a deprecation warning that is promoted
+# to error in our pytest configuration; ignore it for this unit test module.
+warnings.filterwarnings(
+    "ignore",
+    message="pkg_resources is deprecated as an API.*",
+    category=UserWarning,
+)
+
+
+def _install_cv2_stub_if_unavailable():
+    try:
+        import cv2  # noqa: F401
+        return
+    except Exception:
+        pass
+
+    stub = types.ModuleType("cv2")
+
+    stub.INTER_LINEAR = 1
+    stub.INTER_CUBIC = 2
+    stub.BORDER_CONSTANT = 0
+    stub.BORDER_REPLICATE = 1
+    stub.COLOR_BGR2RGB = 0
+    stub.COLOR_BGR2GRAY = 1
+    stub.COLOR_GRAY2BGR = 2
+    stub.IMREAD_IGNORE_ORIENTATION = 128
+    stub.IMREAD_COLOR = 1
+    stub.RETR_LIST = 1
+    stub.CHAIN_APPROX_SIMPLE = 2
+
+    def _missing(*_args, **_kwargs):
+        raise RuntimeError("cv2 runtime call is unavailable in this test environment")
+
+    def _module_getattr(name):
+        if name.isupper():
+            return 0
+        return _missing
+
+    stub.__getattr__ = _module_getattr
+    sys.modules["cv2"] = stub
+
+
+_install_cv2_stub_if_unavailable()
+
+from api.db import TenantPermission
+from api.db.services.document_service import DocumentService
+from api.db.services.knowledgebase_service import KnowledgebaseService
+from common.constants import StatusEnum
+
+
+def _unwrapped_kb_accessible():
+    return KnowledgebaseService.accessible.__func__.__wrapped__
+
+
+def _unwrapped_doc_accessible():
+    return DocumentService.accessible.__func__.__wrapped__
+
+
+def test_private_dataset_is_not_accessible_to_other_tenant_member(monkeypatch):
+    kb = SimpleNamespace(
+        id="kb-private",
+        tenant_id="owner-1",
+        permission=TenantPermission.ME.value,
+        status=StatusEnum.VALID.value,
+    )
+
+    monkeypatch.setattr(KnowledgebaseService, "get_by_id", classmethod(lambda cls, kb_id: (True, kb)))
+    monkeypatch.setattr(
+        "api.db.services.knowledgebase_service.TenantService.get_joined_tenants_by_user_id",
+        lambda _user_id: [{"tenant_id": "owner-1"}],
+    )
+
+    assert _unwrapped_kb_accessible()(KnowledgebaseService, "kb-private", "member-2") is False
+
+
+def test_team_dataset_is_accessible_to_joined_tenant_member(monkeypatch):
+    kb = SimpleNamespace(
+        id="kb-team",
+        tenant_id="owner-1",
+        permission=TenantPermission.TEAM.value,
+        status=StatusEnum.VALID.value,
+    )
+
+    monkeypatch.setattr(KnowledgebaseService, "get_by_id", classmethod(lambda cls, kb_id: (True, kb)))
+    monkeypatch.setattr(
+        "api.db.services.knowledgebase_service.TenantService.get_joined_tenants_by_user_id",
+        lambda _user_id: [{"tenant_id": "owner-1"}],
+    )
+
+    assert _unwrapped_kb_accessible()(KnowledgebaseService, "kb-team", "member-2") is True
+
+
+def test_document_access_respects_dataset_permission(monkeypatch):
+    doc = SimpleNamespace(id="doc-1", kb_id="kb-private")
+
+    monkeypatch.setattr(DocumentService, "get_by_id", classmethod(lambda cls, doc_id: (True, doc)))
+    monkeypatch.setattr(KnowledgebaseService, "accessible", classmethod(lambda cls, kb_id, user_id: False))
+
+    assert _unwrapped_doc_accessible()(DocumentService, "doc-1", "member-2") is False