September 2024 - dovecot

allow_nets check failure still performs LDAP bind authentication
by Florian Wunderlich 04 Sep '24

04 Sep '24

Postfix authentication via Dovecot. Dovecot performs the allow_nets check, which fails. It then still attempts to authenticate the user via LDAP bind, thus allowing DoS attacks where the entry in the directory will be locked after a few failed attempts. dovecot --version: 2.3.19.1 (9b53102964) Debian GNU/Linux 12 (bookworm), x86, no NFS Sep 04 07:26:05 postfix/smtpd[48225]: connect from unknown[182.176.211.10] Sep 04 07:26:17 dovecot[33863]: auth: *ldap(XXX,182.176.211.10): allow_nets check failed: IP 182.176.211.10 not in allowed networks* Sep 04 07:26:17 dovecot[33863]: auth: *ldap(XXX,182.176.211.10): Password mismatch (for LDAP bind)* Sep 04 07:26:27 postfix/smtpd[48225]: warning: unknown[182.176.211.10]: SASL LOGIN authentication failed: Connection lost to authentication server, sasl_username=(unavailable) Sep 04 07:26:27 postfix/smtpd[48225]: lost connection after AUTH from unknown[182.176.211.10] Sep 04 07:26:27 postfix/smtpd[48225]: disconnect from unknown[182.176.211.10] ehlo=2 starttls=1 auth=0/1 commands=3/4 The allow_nets extra field comes from LDAP. This works as a pass_filter query is performed first, which returns the allow_nets. /DN is looked up by sending a pass_filter LDAP request and getting the DN from the reply. This is very similar to doing a password lookup. The only difference is that userPassword attribute isn’t returned. Just as with password lookups, the pass_attrs may contain special extra fields./ https://doc.dovecot.org/2.3/configuration_manual/authentication/ldap_bind/#… After this, Dovecot should immediately fail the authentication. /If the user tries to log in from elsewhere, the authentication will fail the same way as if a wrong password was given./ https://doc.dovecot.org/2.3/configuration_manual/authentication/allow_nets/ There is no need to perform the bind authentication. According to the log (and the locked user accounts), it is still performed. Configuration is irrelevant, for completeness’s sake: auth_bind = yes pass_filter = (&(|(objectClass=simpleSecurityObject)(objectClass=posixAccount))(cn=%n)) pass_attrs = \ cn=user, \ allowNets=allow_nets

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What are all the /var/spool/smtpd/offline/1689525601.XXXXlJ85yQ
by Steve Litt 03 Sep '24

03 Sep '24

Hi all, I just filled up my whole /var with zillions of files /var/spool/smtpd/offline , dating back to 2018. What are these files and is it safe for me to delete the ones more than a week old? Thanks, SteveT Steve Litt http://444domains.com

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Inconsistency in map index with dovecot v2.3.21
by Nikolaos Pyrgiotis 02 Sep '24

02 Sep '24

Hello, We have been running dovecot version 2.3.21 since July on debian bookworm system. After upgrading we have seen in the logs similar messages to the following: 2024-08-29T19:33:27.755399+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: Warning: mdbox /path/user1/mdbox/storage: Inconsistency in map index (2213,40 != 2213,56). 2024-08-29T19:33:27.755399+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: Warning: mdbox /path/user1/mdbox/storage: Inconsistency in map index (2213,40 != 2213,56) 2024-08-29T19:33:27.838990+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: sieve: msgid=<39f9c444-0c08-4bda-bfc9-512c34584470(a)modulus.gr>: fileinto action: stored mail into mailbox 'Replies' 2024-08-29T19:33:27.840222+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: Warning: fscking index file /path/user1/mdbox/storage/dovecot.map.index 2024-08-29T19:33:27.953281+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: Warning: mdbox /path/user1/mdbox/storage: rebuilding indexes 2024-08-29T19:37:27.989792+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481249><vhzsLROj0GYQVgcAfAk26A:P1>: Error: Timeout (180s)while waiting for lock for transaction log file /path/user1/mdbox/storage/dovecot.map.index.log (WRITE lock held by pid 481240) 2024-08-29T19:37:27.995913+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481249><vhzsLROj0GYQVgcAfAk26A:P1>: Error: sieve: msgid=<39f9c444-0c08-4bda-bfc9-512c34584470(a)modulus.gr>: fileinto action: failed to store into mailbox 'Mailbox': Timeout (180s) while waiting for lock for transaction log file /path/user1/mdbox/storage/dovecot.map.index.log (WRITE lock held by pid 481240) This has happened a few times since we upgraded always by a lmtp process. It seems to be happening randomly and we have not been able to reproduce it. The mailboxes are stored in a glusterfs server, and we use the dovecot director with shared mailboxes architecture. Usually this was mitigated automatically by dovecot index rebuilding, but last time it happened on a mailbox with a lot of giga byte of mail data the following logs were produced for more than an hour: 2024-08-29T19:45:30.506694+03:00 server1 dovecot: lmtp(user1(a)modulus.gr)<481240><7TMeHNei0GYpeTkA1g8ogQ:P1>: Error: mmap_anon(/path/user/mdbox/mailboxes/Mailbox/dbox-Mails/dovecot.index.cache, 74076160) failed: Cannot allocate memory During that period segfaults starting being generated for the imap processes accessing that mailbox probably caused by timeouts from imap processes attempting to fetch emails from the affected mailbox: [3912187.557029] imap[481783]: segfault at 38 ip 00007fb03248abf8 sp 00007ffc88b264f0 error 4 in libdovecot-storage.so.0.0.0[7fb0323c7000+d8000] likely on CPU 6 (core 3, socket 0) What might be the reason that inconsistency of the map index is introduced on random users? We have seen some other users had similar issues and have mentioned them on this mailing list(dovecot Digest, Vol 249, Issue 4, dovecot Digest, Vol 250, Issue 8)? Is there any update for a mitigation or bug confirmation for dovecot version 2.3.21 that might be responsible? Thank you, Nikos Pyrgiotis

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Fwd: maintainer-feedback requested: [Bug 280929] mail/dovecot move bogus warning "Time moved forwards" to debug
by Larry Rosenman 01 Sep '24

01 Sep '24

Comments from the dovecot community? Aug 19, 2024 11:07:30 AM bugzilla-noreply(a)freebsd.org: Bugzilla Automation <bugzilla(a)FreeBSD.org> has asked Larry Rosenman <ler(a)FreeBSD.org> for maintainer-feedback: Bug 280929: mail/dovecot move bogus warning "Time moved forwards" to debug https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=280929 --- Description --- Dovecot complains about time moving forward, which seems to be due to a broken mechanism (on FreeBSD) used to measure timeouts. This warning spams the maillog up to several hundred times per day. There's an ongoing thread about this issue in the freebsd forums: https://forums.freebsd.org/threads/dovecot-time-moved-forwards.82886 In post #33 RypPn points out the offending line in main.c and in post #34 msplsh suggests instead of completely removing/commenting out the line, it would be more sensible to move it from 'warning' to 'debug'. This is what this patch does: change the log facility to 'debug' to mute that bogus message for standard configurations, but keep it in 'debug' for anyone who might want to debug that issue in the future. I tested the patch as a local patch in poudriere and it builds fine on 13.3-RELEASE with the quarterly and latest branch.

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