[Bug 2107773] Re: [SRU] Enabling FIPS causes SALT to be 8 bytes, but OpenSSL 3.0.2 checks if SALT is < 16 bytes, breaking Dovecot and possibly other packages.
Eric Berry
2107773 at bugs.launchpad.net
Fri Oct 3 22:46:41 UTC 2025
** Merge proposal linked:
https://code.launchpad.net/~ericeberry/ubuntu/+source/dovecot/+git/dovecot/+merge/493829
--
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssl in Ubuntu.
https://bugs.launchpad.net/bugs/2107773
Title:
[SRU] Enabling FIPS causes SALT to be 8 bytes, but OpenSSL 3.0.2
checks if SALT is < 16 bytes, breaking Dovecot and possibly other
packages.
Status in dovecot package in Ubuntu:
Fix Released
Status in openssl package in Ubuntu:
Invalid
Status in dovecot source package in Focal:
Won't Fix
Status in openssl source package in Focal:
Won't Fix
Status in dovecot source package in Jammy:
New
Status in openssl source package in Jammy:
Invalid
Status in dovecot source package in Noble:
New
Status in openssl source package in Noble:
Invalid
Status in dovecot source package in Oracular:
Won't Fix
Status in openssl source package in Oracular:
Won't Fix
Status in dovecot source package in Plucky:
New
Status in openssl source package in Plucky:
Invalid
Status in dovecot source package in Questing:
Fix Released
Status in openssl source package in Questing:
Invalid
Bug description:
[ Impact ]
* When one enables FIPS mode on a Jammy system and then attempts to use Dovecot to create an encrypted mailbox, the module returns a invalid salt length error.
* FIPS mode requires a 16 byte salt for PBEKDF2 and Dovecot is only
requesting 8 bytes of salt. The solution is to modify Dovecot to
request 16 bytes of salt.
[ Test Plan ]
Test 1
------
* Install Dovecot on the system
- sudo apt install dovecot-auth-lua dovecot-core dovecot-gssapi dovecot-imapd dovecot-ldap dovecot-lmtpd dovecot-managesieved dovecot-mysql dovecot-pgsql dovecot-pop3d dovecot-sieve dovecot-solr dovecot-sqlite dovecot-submissiond
* Enable mailbox encryption.
- Add /etc/dovecot/conf.d//mail-crypt.conf to enable mailbox encryption:
mail_location = mbox:~/mail:INBOX=/var/mail/%u
listen = *
mbox_write_locks = fcntl
namespace inbox {
inbox = yes
location =
mailbox Drafts {
special_use = \Drafts
}
mailbox Junk {
special_use = \Junk
}
mailbox Sent {
special_use = \Sent
}
mailbox "Sent Messages" {
special_use = \Sent
}
mailbox Trash {
special_use = \Trash
}
prefix =
}
passdb {
driver = pam
}
userdb {
driver = passwd
}
mail_plugins = $mail_plugins mail_crypt
plugin {
mail_crypt_curve = secp521r1
mail_crypt_save_version=2
}
mail_attribute_dict = file:%h/Maildir/dovecot-attributes
imap_metadata = yes
* Add a test user to the system:
- sudo useradd -m -s /bin/bash -p <password> <username>
* Issue the following command to create an encrypted mailbox:
- sudo doveadm -o plugin/mail_crypt_private_password=e32f1f174d7576716d5df899e7d5cb6b64cdb33584c71882e9f7e1f79f2e695e mailbox cryptokey generate -u <username>
* Verify that no error occurs.
* Enable FIPS on a Jammy system.
- sudo pro attach <token>
- sudo pro enable fips-updates
- sudo reboot
(To test FIPS on a Noble system)
- sudo add-apt-repository ppa:fips-cc-stig/fips-under-certification
- sudo apt install -y ubuntu-fips openssh-server=1:9.6p1-3ubuntu13+Fips1~rc0 \
openssh-client=1:9.6p1-3ubuntu13+Fips1~rc0 \
openssh-sftp-server=1:9.6p1-3ubuntu13+Fips1~rc0 \
--allow-downgrades --yes
* Reboot
* Delete the mailbox
- rm -rf ~/mail
* Issue the following command to create an encrypted mailbox:
- sudo doveadm -o plugin/mail_crypt_private_password=e32f1f174d7576716d5df899e7d5cb6b64cdb33584c71882e9f7e1f79f2e695e mailbox cryptokey generate -u <username>
* Verify that an error occurs.
* Update Dovecot to the fixed version.
* Repeat the commands to delete the mailbox and to create an encrypted
mailbox.
* After installing the fix, verify that no error occurs.
Test 2 - This test needs to be performed on all releasess
------
* Setup dovecot on jammy without fips as before.
* Also install postfix and mailutils
- sudo apt install postfix mailtuils
- Setup postfix as a local server
* Send mail to the user on the same host:
- echo "This is a test" | mail -s "TEST" <username>@<hostname>
* Connect to the imaps mailbox from another system and verify messages can be read:
- openssl s_client --connect <hostname>:993
- a login <username> <password>
- b select inbox
- c fetch 1:* all
* Verify that message can be viewed.
* Update dovecot to the fixed version and verify that the message can still be downloaded
* Upgrade to fips
[ Where problems could occur ]
* The increased salt size of 16 bytes could potentially cause issues in allocated data structures, but unit tests don't seem to have a probleem.
* The patch is recent and has not been distributed in an upstream release.
[ Other Info ]
This is really only needed on systems where FIPS is supported, i.e.
Jammy and Noble and 26.04, but patches have been provided for
oracular, plucky, and questing.
--------------
We deployed Ubuntu Server 22.04 FIPS on Azure as it is now a FIPS Certified release. See https://ubuntu.com/blog/fips-140-3-for-ubuntu-22-04lts
~# lsb_release -rd
Description: Ubuntu 22.04.5 LTS
Release: 22.04
After installing Ubuntu Server 22.04 FIPS, we then deployed Dovecot modules as shown here:
--------------
# apt search dovecot | grep "install"
WARNING: apt does not have a stable CLI interface. Use with caution in
scripts.
dovecot-core/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-imapd/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-lmtpd/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-managesieved/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-mysql/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-pop3d/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
dovecot-sieve/jammy-updates,jammy-security,now 1:2.3.16+dfsg1-3ubuntu2.4 amd64 [installed]
~# apt-cache policy dovecot-core
dovecot-core:
Installed: 1:2.3.16+dfsg1-3ubuntu2.4
Candidate: 1:2.3.16+dfsg1-3ubuntu2.4
Version table:
*** 1:2.3.16+dfsg1-3ubuntu2.4 500
500 http://azure.archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
500 http://azure.archive.ubuntu.com/ubuntu jammy-security/main amd64 Packages
100 /var/lib/dpkg/status
1:2.3.16+dfsg1-3ubuntu2 500
500 http://azure.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
-------------
We attempted to add a mailbox with encryption:
-------------
sudo -u vmail doveadm -o plugin/mail_crypt_private_password=e32f1f174d7576716d5df899e7d5cb6b64cdb33584c71882e9f7e1f79f2e695e mailbox cryptokey generate -u user at domain.com
doveadm(user at domain.com): Error: mail_crypt_user_generate_keypair(user at domain.com) failed: error:1C800070:Provider routines::invalid salt length
doveadm(user at domain.com): Warning: mailbox cryptokey generate: Nothing was matched. Use -U or specify mask?
Folder Public ID
x ERROR: error:1C800070:Provider routines::invalid salt length
Segmentation fault
-------------
After researching the error, I found a single note in the OpenSSL bug tracker referencing the error.
https://github.com/openssl/openssl/issues/24962
The suggested options are not available as they defeat the purpose of
being FIPS compliant and certified.
As a result, Dovecot is completely broken on 22.04 FIPS if using
encrypted mailboxes. (At least in our testing)
Expected behavior:
The SALT length should match what the required check is, which is 16
bytes. Dovecot should utilize an appropriate version to produce
encryption keys using the required SALT length.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/dovecot/+bug/2107773/+subscriptions
More information about the foundations-bugs
mailing list