Hello,
On version 2.3.20 (80a5ac675d), I have a problem with submission-login when using GSSAPI auth : it's not working, probably due to AUTH line being too long. It appeared after I activated PAC on my Kerberos infrastructure. Now the Kerberos tickets contains MS-PAC data and are bigger. It's part of the RFC and is a valid use case : https://datatracker.ietf.org/doc/html/rfc4120#section-5.2.6
Logs :
May 30 17:13:00 auth: Debug: auth client connected (pid=378) May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Sent: 220 mail.int.k8s.lemarchand.io Dovecot ready. May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Received new command: EHLO [192.168.202.16] May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: New command May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Execute command May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Pipeline blocked May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: 250 reply: Submitted May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Replied May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Ready to reply May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Trigger output May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Next to reply May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Sending replies May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Next to reply May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Completed May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Pipeline unblocked May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Connection state reset May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: 250 reply: Sent: 250-mail.int.k8s.lemarchand.io 8BITMIME AUTH GSSAPI PLAIN LOGIN BURL imap CHUNKING ENHANCEDSTATUSCODES SIZE P IPELINING May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Finished May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: Destroy May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command EHLO: 250 reply: Destroy May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Trigger output May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: No more commands pending May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Sending replies May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: No more commands pending May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Client sent invalid command: Command line is too long May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Invalid command May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: 500 reply: Submitted May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Replied May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Ready to reply May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Trigger output May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Sending replies May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Next to reply May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Completed May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: 500 reply: Sent: 500 5.5.2 Line too long May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Finished May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: Destroy May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: command [unknown]: 500 reply: Destroy May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Trigger output May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: No more commands pending May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Sending replies May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: No more commands pending May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Remote closed connection: Connection closed May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Disconnected: Connection closed May 30 17:13:00 submission-login: Debug: smtp-server: conn 10.200.114.128:13587 [1]: Connection state reset
My guess is that it's due to https://github.com/dovecot/core/blob/main/src/lib-smtp/smtp-common.h#L10 being too low (is it configurable ?), but I didn't read the code thoroughly. Red Hat IDM now activates MS-PAC by default, so any installation based on IDM (or FreeIPA) may have the same problem. What's your opinion ? Bug ?
Mail sent using password auth :'(
-- Thomas Lemarchand