BUG: _presence_ of valid openssl.cnf Option = 'ServerPreference' causes Dovecot submission relay FAIL: "failed: Failed to initialize SSL: ..."

PGNet Dev pgnet.dev at gmail.com
Tue Aug 25 03:17:30 EEST 2020


 I've

	dovecot --version
		2.3.10.1 (a3d0e1171)
	openssl version
		OpenSSL 1.1.1g FIPS  21 Apr 2020

, atm on Fedora32.

I configure

	/etc/pki/tls/openssl.cnf

to set preferences for apps' usage, e.g. Postfix etc; Typically, here

	cat /etc/pki/tls/openssl.cnf

		openssl_conf = default_conf

		[default_conf]
		ssl_conf = ssl_sect

		[ssl_sect]
		system_default = system_default_sect

		[system_default_sect]
		MinProtocol = TLSv1.2
		Ciphersuites = TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256
		CipherString = ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256
		Options = PrioritizeChaCha,ServerPreference

However, any/all sends from local client via Dovecot submission -- from an instance on the same server --  FAILS with that^^ openssl.cnf,

	==> /var/log/dovecot/dovecot.log <==
		...
		2020-08-24 17:04:42 submission(testuser at example.com)<D4c5c6itUg2sHgsH>: Error: smtp-client: conn int.mx.example.net:465 (10.0.4.65:465) [1]: connect(int.mx.example.net:465) failed: Failed to initialize SSL: Couldn't initialize SSL context: Can't load SSL certificate: error:14187180:SSL routines:ssl_do_config:bad value: section=system_default, cmd=Options, arg=ServerPreference,PrioritizeChaCha
		2020-08-24 17:04:42 submission(testuser at example.com)<D4c5c6itUg2sHgsH>: Error: Failed to establish relay connection: Failed to connect to remote server
		...

editing,

-		Options = PrioritizeChaCha,ServerPreference
+		Options = PrioritizeChaCha

cures the error

	==> /var/log/dovecot/dovecot.log <==
		...
		2020-08-24 17:08:04 submission(testuser at example.com)<Uow+f6itZg2sHgsH>: Info: Successfully relayed message: from=<testuser at example.com>, size=433, id=Mh4pJWRWRF9jHQAAVDn7pA, nrcpt=1, reply=`250 2.0.0 Ok: queued as 4Bb8TJ4VQbz7v6t'
		...

checking ssl docs

	https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html

BOTH are valid 'Options',

	...
	ServerPreference: use server and not client preference order when determining which cipher suite, signature algorithm or elliptic curve to use for an incoming connection. Equivalent to SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.

	PrioritizeChaCha: prioritizes ChaCha ciphers when the client has a ChaCha20 cipher at the top of its preference list. This usually indicates a mobile client is in use. Equivalent to SSL_OP_PRIORITIZE_CHACHA. Only used by servers.
	...


The mere presence of that option in a system-wide openssl.cnf shouldn't cause a Dovecot submission failure.



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