2902c9cc82
- login_user clears any pre-login session state before stamping user_id/pw_changed_at/admin so a fixated cookie value cannot smuggle data past the login boundary - logout_user now session.clear()s instead of only popping user_id, removing leftover pw_changed_at/admin markers - CSRF token comparison uses hmac.compare_digest - load_current_user rejects sessions where the stamped admin flag no longer matches the user row, preventing a demoted admin from retaining elevated access until next password change (backward-compatible: sessions issued pre-upgrade lack the marker and pass through until next login)
143 lines
3.9 KiB
Python
143 lines
3.9 KiB
Python
from datetime import datetime
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from functools import wraps
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from typing import Callable, TypeVar
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from urllib.parse import quote, unquote
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from flask import abort, g, redirect, request, session
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from sqlalchemy import select
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from werkzeug.security import check_password_hash, generate_password_hash
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from l4d2web.db import session_scope
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from l4d2web.models import User
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F = TypeVar("F", bound=Callable)
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def hash_password(raw: str) -> str:
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return generate_password_hash(raw)
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def verify_password(raw: str, digest: str) -> bool:
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return check_password_hash(digest, raw)
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MIN_PASSWORD_LENGTH = 8
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def validate_new_password(raw: str) -> str | None:
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if raw == "":
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return "password must not be empty"
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if len(raw) < MIN_PASSWORD_LENGTH:
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return f"password must be at least {MIN_PASSWORD_LENGTH} characters"
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return None
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def load_current_user() -> None:
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user_id = session.get("user_id")
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if user_id is None:
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g.user = None
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return
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with session_scope() as db:
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user = db.scalar(select(User).where(User.id == int(user_id)))
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if user is None or not user.active:
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g.user = None
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return
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marker = session.get("pw_changed_at")
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if marker is None:
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g.user = None
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return
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try:
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marker_dt = datetime.fromisoformat(marker)
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except ValueError:
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g.user = None
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return
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# user.password_changed_at comes back naive from SQLite; strip tz from the
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# marker so an aware-marker session (just stamped from an in-memory user)
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# compares cleanly with a freshly-loaded user row.
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if marker_dt.tzinfo is not None:
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marker_dt = marker_dt.replace(tzinfo=None)
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if marker_dt < user.password_changed_at:
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g.user = None
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return
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# Role change since login → reject. Prevents a demoted admin from
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# keeping admin until their next password change. Absence of the marker
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# means a pre-upgrade session; let it through and the next login will
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# stamp it.
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session_admin = session.get("admin")
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if session_admin is not None and bool(session_admin) != bool(user.admin):
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g.user = None
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return
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g.user = user
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def current_user() -> User | None:
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return getattr(g, "user", None)
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def login_user(user_id: int, password_changed_at, admin: bool) -> None:
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# Drop any pre-login session state so a fixated cookie value can't smuggle
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# data past the login boundary. The next request's csrf_protect hook will
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# mint a fresh csrf_token.
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session.clear()
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session["user_id"] = user_id
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session["pw_changed_at"] = password_changed_at.isoformat()
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session["admin"] = bool(admin)
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def logout_user() -> None:
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session.clear()
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def is_safe_next(target: str | None) -> bool:
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if not target:
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return False
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if not target.startswith("/"):
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return False
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if target.startswith("//"):
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return False
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if "://" in target:
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return False
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if "\\" in target:
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return False
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decoded_target = unquote(target)
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if decoded_target.startswith("//"):
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return False
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if "://" in decoded_target:
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return False
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if "\\" in decoded_target:
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return False
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return True
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def login_redirect_for_current_request():
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target = request.full_path.rstrip("?")
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if is_safe_next(target):
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return redirect(f"/login?next={quote(target, safe='/')}")
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return redirect("/login")
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def require_login(func: F) -> F:
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@wraps(func)
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def wrapper(*args, **kwargs):
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if current_user() is None:
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return login_redirect_for_current_request()
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return func(*args, **kwargs)
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return wrapper # type: ignore[return-value]
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def require_admin(func: F) -> F:
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@wraps(func)
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def wrapper(*args, **kwargs):
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user = current_user()
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if user is None:
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return login_redirect_for_current_request()
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if not user.admin:
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abort(403)
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return func(*args, **kwargs)
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return wrapper # type: ignore[return-value]
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