bpo-40695: Limit hashlib builtin hash fallback (GH-20259)
:mod:`hashlib` no longer falls back to builtin hash implementations when
OpenSSL provides a hash digest and the algorithm is blocked by security
policy.
Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit 4cc2f9348c6e899b76af811fa3bb6c60de642a28)
Co-authored-by: Christian Heimes <christian@python.org>
diff --git a/Lib/hashlib.py b/Lib/hashlib.py
index 8d119a4..1b6e502 100644
--- a/Lib/hashlib.py
+++ b/Lib/hashlib.py
@@ -127,8 +127,9 @@
# SHA3/shake are available in OpenSSL 1.1.1+
f = getattr(_hashlib, 'openssl_' + name)
# Allow the C module to raise ValueError. The function will be
- # defined but the hash not actually available thanks to OpenSSL.
- f()
+ # defined but the hash not actually available. Don't fall back to
+ # builtin if the current security policy blocks a digest, bpo#40695.
+ f(usedforsecurity=False)
# Use the C function directly (very fast)
return f
except (AttributeError, ValueError):