Bug 2402944 - opendkim private key permission error and multiple users in group 0
Summary: opendkim private key permission error and multiple users in group 0
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: opendkim
Version: 42
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Jonathan Wright
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-10-09 21:27 UTC by atcorduneanu
Modified: 2026-06-09 13:15 UTC (History)
3 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2026-06-09 13:15:28 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description atcorduneanu 2025-10-09 21:27:33 UTC
after generating the keypair with opendkim-genkey I placed in the path recommended in /usr/share/doc/opendkim/README (/var/db/dkim) with the recommended permissions.

When trying to start the service, the error that I encounter is:
/var/db/dkim/mail09oct2025.private: key data is not secure: opendkim is in group 0 which has multiple users (e.g., "sync")

From what I'm able to get from the message, opendkim would not start if the user is in group 0, where there are other members.
But the user opendkim is not in group 0. And in fedora there are plenty of users that have 0 as their primary group.

[root@mail ~]# id opendkim
uid=990(opendkim) gid=990(opendkim) groups=990(opendkim),12(mail)

[root@mail ~]# ls -laZ /var/db/dkim/
total 4
drwx------. 1 opendkim opendkim system_u:object_r:system_db_t:s0  42 Oct  9 21:23 .
drwxr-xr-x. 1 root     root     system_u:object_r:system_db_t:s0  16 Oct  9 21:23 ..
-rw-------. 1 opendkim opendkim system_u:object_r:system_db_t:s0 912 Oct  9 20:36 mail09oct2025.private

[root@mail ~]# getent group 0
root:x:0:
[root@mail ~]# awk -F':' '$4 == 0 {print $1" - "$4}' /etc/passwd
root - 0
sync - 0
shutdown - 0
halt - 0
operator - 0


Also found here: https://serverfault.com/questions/1025867/dovecot-postfix-cannot-retrieve-email-from-server-due-to-connection-timing-out/1056084#1056084

Reproducible: Always

Steps to Reproduce:
1.opendkim-genkey -r -s mail09oct2025 -d tpc.jacket.lime
2.create and set the right permissions and labels on /var/db/dkim
3. move key to /var/db/dkim
4. start the service
Actual Results:
The service does not start, and the error message is the following:
/var/db/dkim/mail09oct2025.private: key data is not secure: opendkim is in group 0 which has multiple users (e.g., "sync")

Expected Results:
Should have started as the permissions on the key and path seem to align with the recommendations in the README

Additional Information:
As a workaround, /etc/opendkim.conf could have the option:
RequireSafeKeys False

but having this check turned off is not pretty and is probably a bad idea for users.

Comment 1 cube00 2025-10-27 20:10:24 UTC
I checked through the code [1] and it's searching up the directory hierarchy.

The error message is misleading, the issue is with the file system permissions not the opendkim account.

Eventually it finds write permissions for the root group on / which fails because it doesn't allow any files/directories to have group write where the group has multiple users in it.

This group write permission on the filesystem root directory was added in Fedora 40 on the cloud images. I haven't checked the other images.

Fedora 39
$ ls -al /
dr-xr-xr-x.   1 root root  138 Nov  1  2023 .

Fedora 40
$ ls -al /
drwxrwxr-x.   1 root root  212 Nov 10  2024 .

I removed group write from the / directory to verify this is the only directory in the hierarchy causing the issue.

[1]: https://github.com/trusteddomainproject/OpenDKIM/blob/5c539587561785a66c1f67f720f2fb741f320785/opendkim/opendkim.c#L4452

Comment 2 Fedora Release Engineering 2026-05-06 14:33:24 UTC
This message is a reminder that Fedora Linux 42 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 42 on 2026-05-13.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
'version' of '42'.

Package Maintainer: If you wish for this bug to remain open because you
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Click the "Show advanced fields" button if you do not see it.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora Linux 42 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora Linux, you are encouraged to change the 'version' to a later version
prior to this bug being closed.

Comment 3 Aoife Moloney 2026-06-09 13:15:28 UTC
Fedora Linux 42 entered end-of-life (EOL) status on 2026-05-27.

Fedora Linux 42 is no longer maintained, which means that it
will not receive any further security or bug fix updates. As a result we
are closing this bug.

If you can reproduce this bug against a currently maintained version of Fedora Linux
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