From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: szelenka@gmail.com
Subject: BUG #17593: min key size 112 bits from FIPS SP800-131 requirement for HMAC-SHA raises exception in SCRAM-SHA-256
Date: Thu, 25 Aug 2022 17:26:08 +0000
Message-ID: <17593-3b34abcaff0d47e4@postgresql.org> (raw)
The following bug has been logged on the website:
Bug reference: 17593
Logged by: Scott Zelenka
Email address: szelenka@gmail.com
PostgreSQL version: 14.5
Operating system: Ubuntu 20.04
Description:
Running postgres with:
postgres -D /home/postgres/pgdata/pgroot/data \
--password_encryption=scram-sha-256 \
--ssl=on \
--ssl_cert_file='/run/certs/server.crt' \
--ssl_key_file='/run/certs/server.key'
Will raise an error when attempting to create a ROLE with a SCRAM-SHA-256
password:
CREATE ROLE "test-enc-pw" LOGIN ENCRYPTED PASSWORD
'SCRAM-SHA-256$4096:RlI0UDRNeEFSRUp0Y29kWA==$knE29fNkMKTvocaIou0vfZ+J+lwp4hawGKrXPVDOA08=:ZMQb8JU1qRdMv0wjFUBuD/E2G+YJhHV+KBSVzDC6ifA=';
Running on Postgres 125 BETA 3 gives more context into the error:
ERROR: could not compute server key: invalid key length
The "invalid key length" is returned from the FIPS Validated OpenSSL library
Postgres is linked to. Where it is enforcing FIPS SP800-131 requirement for
HMAC-SHA, minimum key size is 112 bits when used for security purposes.
This appears to be triggered during the NULL password check during CREATE
ROLE:
https://github.com/postgres/postgres/blob/REL_15_BETA3/src/backend/commands/user.c#L373
Attaching a debugger, we can see that in normal code execution path, the
plain_crypt_verify method should return STATUS_ERROR (because the password
is not actually empty) then continue on it’s way to perform the actual
encryption. But because we specify SCRAM-SHA we trigger
scram_verify_plain_password:
https://github.com/postgres/postgres/blob/REL_15_BETA3/src/backend/libpq/crypt.c#L236-L239
Which causes it to error out, rather than returning a STATUS_ERROR like the
working path(s).
There seems to be a conflict with how the NULL password is checked for, and
enforcement of FIPS SP800-131 by a FIPS Validated OpenSSL library.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-bugs@postgresql.org
Cc: noreply@postgresql.org, pgsql-bugs@lists.postgresql.org, szelenka@gmail.com
Subject: Re: BUG #17593: min key size 112 bits from FIPS SP800-131 requirement for HMAC-SHA raises exception in SCRAM-SHA-256
In-Reply-To: <17593-3b34abcaff0d47e4@postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox