Re: Permission denied UNIX perms appear ok (ACL/MAC wrong?))

24 Aug 2022 · *austin@mail*


      There are a number of issues that can appear to be ACL issues when in fact
its something else.
As other's have mentioned, AppArmor profiles and SELinux contexts can be
checked and are the most common. There are ACL permissions as well if you
enabled ACL (they are not enabled by default on Ubuntu server).
I've occasionally (rarely) seen some weird interactions with sockets
between MDA and MTA if the permissions on the directory were not set
correctly.
Additionally, if a mount permission mask is being used, that can
occasionally cause similar issues as well, as is often the case with using
an NTFS backing filesystem for maildir that's been mounted with unix perms.
There can also be some edge-cases with permissions in Ubuntu's flavored
snap containers as well as docker containers and custom sieves.
Its difficult to say with any accuracy what is causing your issue with the
information provided.
Have you increased the verbosity of the logging?
If all of the normal culprits do not stand out, maybe some others will have
an idea.
As a final fallback you can always set a breakpoint and use a reverse
debugger. Its not going to be performant but it will at least narrow down
where the issue is coming from, and what the intermediate states were that
led to the error so you can save/replicate them moving forward for
resolution. Non-determinism can creep into code in a lot of different ways.
Best Regards,
N
On Tue, Aug 23, 2022 at 4:53 AM Austin Witmer <austin96@emypeople.net>
wrote:
...
Here is the output of dovecot -n
*austin@mail*:*~*$ doveconf -n
# 2.3.16 (7e2e900c1a): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.16 (09c29328)
# OS: Linux 5.15.0-46-generic x86_64 Ubuntu 22.04.1 LTS
# Hostname: mail
auth_mechanisms = plain login
listen = *
mail_location = mbox:~/mail:INBOX=/var/mail/%u
mail_privileged_group = mail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags
copy include variables body enotify environment mailbox date index ihave
duplicate mime foreverypart extracttext
namespace inbox {
inbox = yes
location =
mailbox Drafts {
special_use = \Drafts
}
mailbox Junk {
special_use = \Junk
}
mailbox Sent {
auto = subscribe
special_use = \Sent
}
mailbox "Sent Messages" {
special_use = \Sent
}
mailbox Spam {
auto = subscribe
}
mailbox Trash {
auto = subscribe
special_use = \Trash
}
prefix =
}
passdb {
driver = pam
}
passdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
passdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
plugin {
sieve =
file:/mnt/volume1/mailserver/plain/sieve/%d/%n/scripts;active=/mnt/volume1/mailserver/plain/sieve/%d/%n/%n.sieve
sieve_before = /var/lib/dovecot/sieve/
sieve_global_dir = /var/lib/dovecot/sieve/
sieve_global_path = /var/lib/dovecot/sieve/default.sieve
sieve_user_log =
file:/mnt/volume1/mailserver/plain/sieve/%d/%n/sieve_error.log
}
protocols = imap lmtp pop3 imap lmtp sieve pop3
service auth {
unix_listener /var/spool/postfix/private/auth {
group = postfix
mode = 0660
user = postfix
}
}
service imap-login {
inet_listener imap {
port = 0
}
inet_listener imaps {
port = 993
}
}
service lmtp {
unix_listener /var/spool/postfix/private/dovecot-lmtp {
group = postfix
mode = 0600
user = postfix
}
}
service managesieve-login {
inet_listener sieve {
port = 4190
}
service_count = 1
}
ssl = required
ssl_cert = </etc/letsencrypt/live/mail.mydomain.com/fullchain.pem
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_prefer_server_ciphers = yes
userdb {
driver = passwd
}
userdb {
driver = prefetch
}
userdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
userdb {
driver = prefetch
}
userdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
protocol lmtp {
hostname = mail.mydomain.com
mail_plugins = " sieve"
postmaster_address = postmaster@mydomain.com
}
protocol lda {
mail_plugins = " sieve"
}
Austin Witmer
On Aug 20, 2022, at 12:09 PM, Austin Witmer <austin96@emypeople.net>
wrote:
And no, I don’t think I am using ACL’s.
getfacl austin /mnt/volume1/mailserver/plain/maildir/
getfacl: austin: No such file or directory
getfacl: Removing leading '/' from absolute path names
# file: mnt/volume1/mailserver/plain/maildir/
# owner: austin
# group: austin
user::rwx
group::rwx
other::r--
Austin Witmer
On Aug 20, 2022, at 11:15 AM, spi <spi@nurfuerspam.de> wrote:

Am 20.08.22 um 16:52 schrieb Austin Witmer:
Hello all!
Recently I upgraded my mail server to Ubuntu 22.04 LTS and ever since
then I am periodically getting some dovecot errors like the below in
my mail log. As far as I can tell, my unix perms are just fine. What
is ACL/MAC?
Aug 20 14:41:58 mail dovecot:
imap(user@domain.com)<56316><1NieGKPmuOdKwxVI>: Error: Mailbox INBOX:
stat(/mnt/volume1/mailserver/plain/maildir/
domain.com/user/dovecot.index.log
<http://domain.com/user/dovecot.index.log>) failed: Permission denied
(euid=1000(austin) egid=1000(austin) UNIX perms appear ok (ACL/MAC
wrong?))
And here is the listing showing the permissions for that file.
*austin@mail*:*~*$ ls -la
/mnt/volume1/mailserver/plain/maildir/domain.com/user/dovecot.index.log
<http://domain.com/user/dovecot.index.log>
-rwxrwxr-- 1 austin austin 15796 Aug 20 14:41
*/mnt/volume1/mailserver/plain/maildir/domain.com/user/dovecot.index.log
<http://domain.com/user/dovecot.index.log>*
What in the world is causing these errors, and what can I do about them?
Thanks in advance!
Austin Witmer
Do you use any ACLs? Is this just a block device mounted or do you use
any network file sharing like nfs?
ACLs you can check by 'getfacl foo'.
--
Cheers
spi

Re: Permission denied UNIX perms appear ok (ACL/MAC wrong?))

lorek