fix(security): harden uploads and wecom binding

backend/app/api/upload.py

@@ -1,12 +1,15 @@
 import uuid
+import io
+import warnings
 from datetime import date
 from pathlib import PurePosixPath
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends, File, HTTPException, UploadFile
+from PIL import Image, UnidentifiedImageError
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.database import get_db
 from app.middleware.auth import get_current_user, require_any_role
-from app.services.minio_client import generate_presigned_upload_url, generate_presigned_download_url
+from app.services.minio_client import generate_presigned_download_url, put_validated_image
 from app.models.visit import Visit
 
 router = APIRouter(prefix="/upload", tags=["Upload"])
@@ -16,16 +19,17 @@ _IMAGE_TYPES = {
     "image/png": "png",
     "image/webp": "webp",
 }
+MAX_IMAGE_BYTES = 10 * 1024 * 1024
+MAX_IMAGE_PIXELS = 25_000_000
 
 
 def validate_image_upload(filename: str, content_type: str) -> str:
-    """Validate client-declared image metadata before issuing a short-lived PUT URL."""
-    extension = _IMAGE_TYPES.get(content_type.lower())
-    if not extension:
+    """Validate image metadata before accepting bytes for server-side verification."""
+    if content_type.lower() not in _IMAGE_TYPES:
         raise HTTPException(status_code=400, detail="Only JPEG, PNG, and WebP images are supported")
     if PurePosixPath(filename).suffix.lower() not in {".jpg", ".jpeg", ".png", ".webp"}:
         raise HTTPException(status_code=400, detail="Invalid image filename extension")
-    return extension
+    return _IMAGE_TYPES[content_type.lower()]
 
 
 def build_object_key(user_id: str, extension: str) -> str:
@@ -44,22 +48,39 @@ def is_owned_upload_key(object_key: str, user_id: str) -> bool:
     )
 
 
-@router.post("/presigned-url")
-async def get_presigned_upload_url(
-    filename: str,
-    content_type: str = "image/jpeg",
+def normalize_image(image_bytes: bytes) -> bytes:
+    """Verify image bytes, enforce a pixel limit, and strip active/metadata content by re-encoding."""
+    if not image_bytes or len(image_bytes) > MAX_IMAGE_BYTES:
+        raise HTTPException(status_code=413, detail="Image must be between 1 byte and 10 MB")
+    try:
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", Image.DecompressionBombWarning)
+            with Image.open(io.BytesIO(image_bytes)) as image:
+                image.verify()
+            with Image.open(io.BytesIO(image_bytes)) as image:
+                if image.width * image.height > MAX_IMAGE_PIXELS:
+                    raise HTTPException(status_code=413, detail="Image dimensions are too large")
+                normalized = image.convert("RGB")
+                output = io.BytesIO()
+                normalized.save(output, format="JPEG", quality=85, optimize=True)
+                return output.getvalue()
+    except HTTPException:
+        raise
+    except (Image.DecompressionBombError, Image.DecompressionBombWarning, OSError, UnidentifiedImageError, ValueError) as exc:
+        raise HTTPException(status_code=400, detail="Invalid image content") from exc
+
+
+@router.post("/image")
+async def upload_image(
+    file: UploadFile = File(...),
     current_user: dict = Depends(require_any_role),
 ):
-    """Get a presigned PUT URL for direct MinIO upload."""
-    extension = validate_image_upload(filename, content_type)
-    object_key = build_object_key(current_user["user_id"], extension)
-
-    url = generate_presigned_upload_url(object_key)
-
-    return {
-        "upload_url": url,
-        "object_key": object_key,
-    }
+    """Validate and normalize an image before persisting it to private object storage."""
+    validate_image_upload(file.filename or "upload.jpg", file.content_type or "")
+    normalized = normalize_image(await file.read(MAX_IMAGE_BYTES + 1))
+    object_key = build_object_key(current_user["user_id"], "jpg")
+    put_validated_image(object_key, normalized)
+    return {"object_key": object_key}
 
 
 @router.get("/download-url")

backend/app/api/wecom.py

@@ -9,8 +9,9 @@ from fastapi.responses import PlainTextResponse
 from pydantic import BaseModel
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select
+from sqlalchemy.exc import IntegrityError
 from app.config import settings
-from app.database import get_db
+from app.database import async_session, get_db
 from app.middleware.auth import get_current_user, require_director
 from app.models.user import User
 from app.services.wecom import wecom_client, store_bind_token, consume_bind_token
@@ -116,21 +117,20 @@ async def wecom_callback_event(request: Request):
     # Triggers for binding
     if (msg_type == "text" and content == "绑定") or (msg_type == "event" and event == "click" and event_key == "BIND_ACCOUNT"):
         _log.info("wecom bind triggered")
-        _handle_bind_request(from_user)
+        await _handle_bind_request(from_user)
         return PlainTextResponse(content="success")
 
     _log.info("wecom message ignored (no matching action)")
     return PlainTextResponse(content="success")
 
 
-def _handle_bind_request(wecom_userid: str):
+async def _handle_bind_request(wecom_userid: str):
     """Generate bind token, store it, and push a bind link to the user."""
     if not wecom_userid:
         return
 
-    import asyncio
-
-    bind_token = store_bind_token(wecom_userid)
+    async with async_session() as db:
+        bind_token = await store_bind_token(db, wecom_userid)
 
     content = (
         f"【账号绑定】\n\n"
@@ -139,16 +139,7 @@ def _handle_bind_request(wecom_userid: str):
         f"绑定后可使用企微一键登录，并接收填报提醒通知。"
     )
 
-    try:
-        # Must run async in sync context
-        loop = asyncio.get_event_loop()
-    except RuntimeError:
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
-
-    loop.run_until_complete(
-        wecom_client.send_text_message([wecom_userid], content)
-    )
+    await wecom_client.send_text_message([wecom_userid], content)
 
 
 # ── Bind confirmation (JWT-protected) ──
@@ -163,7 +154,7 @@ async def bind_confirm(
     if not data.token:
         raise HTTPException(status_code=400, detail="token 不能为空")
 
-    wecom_userid = consume_bind_token(data.token)
+    wecom_userid = await consume_bind_token(db, data.token)
     if not wecom_userid:
         raise HTTPException(status_code=400, detail="绑定链接已过期或无效，请重新在企微发送「绑定」")
 
@@ -181,7 +172,11 @@ async def bind_confirm(
     )
     user = result.scalar_one()
     user.wecom_userid = wecom_userid
-    await db.commit()
+    try:
+        await db.commit()
+    except IntegrityError as exc:
+        await db.rollback()
+        raise HTTPException(status_code=409, detail="该企业微信已绑定其他账号") from exc
 
     return {"code": 200, "msg": "绑定成功", "wecom_userid": wecom_userid}
 

backend/app/main.py

@@ -51,6 +51,10 @@ async def lifespan(app: FastAPI):
         await conn.run_sync(lambda c: c.exec_driver_sql(
             "ALTER TABLE users ADD COLUMN IF NOT EXISTS color VARCHAR(7)"
         ))
+        await conn.run_sync(lambda c: c.exec_driver_sql(
+            "CREATE UNIQUE INDEX IF NOT EXISTS uq_users_wecom_userid "
+            "ON users (wecom_userid) WHERE wecom_userid IS NOT NULL"
+        ))
         # system_config table for v0.5
         await conn.run_sync(lambda c: c.exec_driver_sql(
             "CREATE TABLE IF NOT EXISTS system_config (key VARCHAR(64) PRIMARY KEY, value TEXT DEFAULT '')"

backend/app/models/__init__.py

@@ -10,6 +10,7 @@ from app.models.daily_note import DailyNote
 from app.models.ai_summary import AISummary
 from app.models.system_config import SystemConfig
 from app.models.leave import Leave
+from app.models.wecom_bind_token import WecomBindToken
 
 __all__ = [
     "User",
@@ -24,4 +25,5 @@ __all__ = [
     "AISummary",
     "SystemConfig",
     "Leave",
+    "WecomBindToken",
 ]

backend/app/models/wecom_bind_token.py

@@ -0,0 +1,18 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.database import Base
+
+
+class WecomBindToken(Base):
+    """A single-use, expiring binding token issued after a verified WeCom callback."""
+
+    __tablename__ = "wecom_bind_tokens"
+
+    token: Mapped[str] = mapped_column(String(64), primary_key=True)
+    wecom_userid: Mapped[str] = mapped_column(String(100), index=True)
+    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), index=True)
+    consumed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

backend/app/services/minio_client.py

@@ -1,4 +1,5 @@
 from datetime import timedelta
+from io import BytesIO
 from minio import Minio
 from app.config import settings
 
@@ -20,10 +21,16 @@ def get_minio_client() -> Minio:
     return _client
 
 
-def generate_presigned_upload_url(object_key: str, expires: int = 600) -> str:
-    """Generate a presigned PUT URL for direct upload to MinIO."""
+def put_validated_image(object_key: str, image_bytes: bytes) -> None:
+    """Store a normalized image only after the API has validated its content."""
     client = get_minio_client()
-    return client.presigned_put_object(settings.MINIO_BUCKET, object_key, expires=timedelta(seconds=expires))
+    client.put_object(
+        settings.MINIO_BUCKET,
+        object_key,
+        BytesIO(image_bytes),
+        length=len(image_bytes),
+        content_type="image/jpeg",
+    )
 
 
 def generate_presigned_download_url(object_key: str, expires: int = 3600) -> str:

backend/app/services/wecom.py

@@ -1,30 +1,41 @@
 import time
 import uuid
+from datetime import datetime, timedelta, timezone
 import httpx
+from sqlalchemy import delete, update
+from sqlalchemy.ext.asyncio import AsyncSession
 from app.config import settings
+from app.models.wecom_bind_token import WecomBindToken
 
-# In-memory bind token store (TTL 600s).  Replace with Redis if scaling to multiple workers.
-_bind_tokens: dict[str, tuple[str, float]] = {}  # token → (wecom_userid, expires_at)
-
-
-def store_bind_token(wecom_userid: str, ttl: int = 600) -> str:
-    """Store a bind token → wecom_userid mapping. Returns the token."""
+async def store_bind_token(db: AsyncSession, wecom_userid: str, ttl: int = 600) -> str:
+    """Persist a one-time bind token so it works across application workers."""
     token = uuid.uuid4().hex
-    _bind_tokens[token] = (wecom_userid, time.time() + ttl)
-    # Cleanup expired tokens
-    now = time.time()
-    for k in list(_bind_tokens):
-        if _bind_tokens[k][1] < now:
-            del _bind_tokens[k]
+    now = datetime.now(timezone.utc)
+    await db.execute(delete(WecomBindToken).where(WecomBindToken.expires_at < now))
+    db.add(WecomBindToken(
+        token=token,
+        wecom_userid=wecom_userid,
+        expires_at=now + timedelta(seconds=ttl),
+    ))
+    await db.commit()
     return token
 
 
-def consume_bind_token(token: str) -> str | None:
-    """Lookup and consume a bind token. Returns wecom_userid or None."""
-    entry = _bind_tokens.pop(token, None)
-    if entry and entry[1] > time.time():
-        return entry[0]
-    return None
+async def consume_bind_token(db: AsyncSession, token: str) -> str | None:
+    """Atomically consume an unexpired binding token and return its WeCom user ID."""
+    now = datetime.now(timezone.utc)
+    result = await db.execute(
+        update(WecomBindToken)
+        .where(
+            WecomBindToken.token == token,
+            WecomBindToken.consumed_at.is_(None),
+            WecomBindToken.expires_at > now,
+        )
+        .values(consumed_at=now)
+        .returning(WecomBindToken.wecom_userid)
+    )
+    await db.commit()
+    return result.scalar_one_or_none()
 
 
 class WecomClient:

backend/requirements.txt

@@ -13,3 +13,4 @@ openpyxl==3.1.5
 apscheduler==3.11.0
 python-dotenv==1.0.1
 pycryptodome
+Pillow==11.1.0

backend/tests/test_upload_security.py

@@ -1,7 +1,13 @@
-from fastapi import HTTPException
+import asyncio
+from io import BytesIO
+from unittest.mock import AsyncMock, MagicMock
 
-from app.api.upload import build_object_key, is_owned_upload_key, validate_image_upload
+from fastapi import HTTPException
+from PIL import Image
+
+from app.api.upload import build_object_key, is_owned_upload_key, normalize_image, validate_image_upload
 from app.config import settings, validate_security_settings
+from app.services.wecom import consume_bind_token, store_bind_token
 
 
 USER_ID = "a2d4447f-7b67-4304-ad9a-953007e75ef2"
@@ -32,6 +38,46 @@ def test_upload_rejects_an_invalid_filename_extension():
         raise AssertionError("invalid extensions must be rejected")
 
 
+def test_image_content_is_normalized_to_jpeg():
+    source = BytesIO()
+    Image.new("RGBA", (8, 8), color=(255, 0, 0, 128)).save(source, format="PNG")
+
+    normalized = normalize_image(source.getvalue())
+
+    with Image.open(BytesIO(normalized)) as image:
+        assert image.format == "JPEG"
+        assert image.mode == "RGB"
+
+
+def test_image_content_rejects_non_images():
+    try:
+        normalize_image(b"not an image")
+    except HTTPException as exc:
+        assert exc.status_code == 400
+    else:
+        raise AssertionError("non-image bytes must be rejected")
+
+
+def test_wecom_binding_tokens_are_persisted_and_consumed_atomically():
+    session = MagicMock()
+    session.execute = AsyncMock()
+    session.commit = AsyncMock()
+
+    token = asyncio.run(store_bind_token(session, "wecom-user"))
+
+    assert len(token) == 32
+    assert session.add.call_args.args[0].wecom_userid == "wecom-user"
+    session.commit.assert_awaited_once()
+
+    result = MagicMock()
+    result.scalar_one_or_none.return_value = "wecom-user"
+    session.execute = AsyncMock(return_value=result)
+    session.commit = AsyncMock()
+
+    assert asyncio.run(consume_bind_token(session, token)) == "wecom-user"
+    session.commit.assert_awaited_once()
+
+
 def test_production_rejects_placeholder_database_configuration(monkeypatch):
     monkeypatch.setattr(settings, "ENVIRONMENT", "production")
     monkeypatch.setattr(settings, "SECRET_KEY", "a" * 32)