peter
90567718b2
A /watch link's token is the credential, and it sat in the database as written. Migration 0107 replaces the column with the token's SHA-256 (the lookup) and a Fernet-encrypted copy (so the owner can copy the same link again); every existing address keeps working, and the downgrade decrypts them back. Without a copy this key can read, a link still opens but its address cannot be shown: "Copy link" then takes the newest link that has one or makes a new one, and the Share dialog says so in that row instead of a broken URL. Making, changing and revoking a link are audited, never with its token or password.
91 lines
3.3 KiB
Python
91 lines
3.3 KiB
Python
import hashlib
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from argon2 import PasswordHasher
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from argon2.exceptions import VerifyMismatchError
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from cryptography.fernet import Fernet
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from app import logs
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from app.config import settings
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log = logs.get_logger(__name__)
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# argon2id with the library defaults (sensible memory/time cost). One shared hasher instance.
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_ph = PasswordHasher()
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def hash_token(raw: str) -> str:
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"""SHA-256 hex digest for storing single-use tokens (email-link tokens, the setup token)
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by hash rather than in cleartext. Not a password hash — these are high-entropy randoms."""
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return hashlib.sha256(raw.encode()).hexdigest()
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def hash_password(password: str) -> str:
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return _ph.hash(password)
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def verify_password(password: str, hashed: str | None) -> bool:
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if not hashed:
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return False
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try:
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return _ph.verify(hashed, password)
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except VerifyMismatchError:
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return False # silent-ok: a wrong password. The commonest path through this function.
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except Exception as exc: # noqa: BLE001 — never raise to the caller, whatever went wrong
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# Everything else is a hash this process cannot USE — truncated in the column, written by
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# a different argon2 build. It is answered as "wrong password", so the owner of that
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# account is locked out by a bug and told they mistyped.
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log.warning(
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"a stored password hash could not be verified",
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extra=logs.event("auth.password.hash_unusable", reason=type(exc).__name__),
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)
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return False
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_fernet: Fernet | None = (
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Fernet(settings.token_encryption_key.encode()) if settings.token_encryption_key else None
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)
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def can_encrypt() -> bool:
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"""Whether a value can be stored encrypted here: TOKEN_ENCRYPTION_KEY is set. Production
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refuses to start without it (`config`); a local box may run without one."""
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return _fernet is not None
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def _require_fernet() -> Fernet:
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if _fernet is None:
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raise RuntimeError("TOKEN_ENCRYPTION_KEY is not configured")
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return _fernet
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def encrypt(value: str | None) -> str | None:
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if value is None:
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return None
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return _require_fernet().encrypt(value.encode()).decode()
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def decrypt(value: str | None) -> str | None:
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if value is None:
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return None
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return _require_fernet().decrypt(value.encode()).decode()
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def decrypt_optional(value: str | None) -> str | None:
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"""Like decrypt() but returns None instead of raising when the value is absent or not a valid
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ciphertext (e.g. a legacy plaintext token stored before encryption) — so callers fall back to
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a refresh rather than erroring."""
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if not value:
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return None
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try:
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return _require_fernet().decrypt(value.encode()).decode()
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except Exception as exc: # noqa: BLE001 — callers fall back to a refresh, never to an error
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# Info rather than warning because the docstring's legacy-plaintext case comes through
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# here too and is harmless. What is NOT harmless looks identical: a rotated
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# TOKEN_ENCRYPTION_KEY turns every stored token unreadable at once, and every account
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# then reads as "not connected" with nothing saying the key is the reason.
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log.info(
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"a stored ciphertext could not be decrypted",
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extra=logs.event("security.decrypt.failed", reason=type(exc).__name__),
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)
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return None
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