You will also need to build the packages with SHA256 file digests. This is taken from /usr/lib/rpm/macros on RHEL 8. 

#	Algorithm to use for generating file checksum digests on build.
#	If not specified or 0, MD5 is used.
#	WARNING: non-MD5 is backwards incompatible with rpm < 4.6!
#	The supported algorithms may depend on the underlying crypto
#	implementation but generally at least the following are supported:
#	1	MD5
#	2	SHA1
#	8	SHA256 (default)
#	9	SHA384
#	10	SHA512
#
%_source_filedigest_algorithm	8
%_binary_filedigest_algorithm	8

Is there any possibility your build process can create the RPM packages using RPM version 4.14 or newer? My understanding is that will fix this issue and will also be backwards compatible with older RHEL/Centos versions.

Comment 4 Pierre Ossman 2022-06-27 08:38:27 CEST

Not at the moment, no. We'd need to check exactly what an upgrade means for the various distributions we try to support.

For now, I'm afraid you'll have to use the appropriate flags to rpm when installing on a FIPS enforcing system.

I did spend some effort researching this before posting here, so I think using RPM 4.14 will fix the issue and will also work on other older RPM platforms. 

https://fedoraproject.org/wiki/Changes/RPM-4.14 indicates they changed RPM to use SHA256 by default and they declare it is backwards compatible. 

From other research I did, there is an indication that building your package with  RPM 4.14 or newer will work on RHEL6, RHEL7, and RHEL8 (and their Centos equivalents) due to the backwards compatibility.

Maybe give it a try when you have a chance? Not sure what other RPM based systems you need to support, but many older ones are past or nearing EOL.

Comment 10 Adam Halim 2024-03-26 15:56:15 CET

In our quest to allow our RPMs to be installed on FIPS systems, we had to
change our file digests to use SHA256 instead of MD5. SHA256 digests have been
supported in RPM since version 4.6, and has been the default since 4.14. 

This means that with this change, we technically raise our minimum server
requirements to have an RPM version of >= 4.6. In practice, this should not
affect anyone as version 4.6 is very old. We had a quick look at some distros
and the oldest and found that SLES 12 has version 4.11, and even CentOS 6 uses
version 4.8.0.

Comment 12 Adam Halim 2024-03-27 16:06:25 CET

Tested build 3537, which is signed and uses SHA256 file digests.

The following distos were tested, with FIPS mode enabled:
* SLES 12   [1]
* SLES 15   [1]
* CentOS 6  [2]
* RHEL 7    [3]
* RHEL 8    [4]
* RHEL 9    [5]

We wanted to test whether signing our RPMs has any impact on installation on
FIPS systems. It seems like this does not matter for the distros that we
tested, see below:

* SLES 12
    ✅ Signed RPM, not trusted key
    ✅ Unsigned RPM
    ✅ MD5 file digest (tl-4.16.0)
        - Interestingly enough, the RPM installed successfully even though the
          RPM had MD5 digests.

* SLES 15
    ✅ Signed RPM, not trusted key
        - We get a warning if the key is not trusted, but the RPM is installed
          successfully.
> warning: tl-4.16.0post-server/packages/thinlinc-server-4.16.0post-3537.x86_64.rpm: Header V4 RSA/SHA256 Signature, key ID 5e02d204: NOKEY 
    ✅ Unsigned RPM
    ✅ MD5 file digest (tl-4.16.0)
        - Interestingly enough, the RPM installed successfully even though the
          RPM had MD5 digests.

* CentOS 6
    ✅ Signed RPM, not trusted key
    - We did not enable FIPS on this system, but the installation went fine.

* RHEL 7
    ✅ Signed RPM, not trusted key
    ✅ Unsigned RPM
    ✅ MD5 file digest (tl-4.16.0)
        - Interestingly enough, the RPM installed successfully even though the
          RPM had MD5 digests.

* RHEL 8
    ✅ Signed RPM, not trusted key
        - We get a warning if the key is not trusted, but the RPM is installed
          successfully.
> warning: tl-4.16.0post-server/packages/thinlinc-server-4.16.0post-3537.x86_64.rpm: Header V4 RSA/SHA256 Signature, key ID 5e02d204: NOKEY
    ✅ Unsigned RPM
        - No warning.
    ❌ MD5 file digest (tl-4.16.0)
> [root@lab-59 ~]# rpm -ivh tl-4.16.0-server/packages/thinlinc-server-4.16.0-3491.x86_64.rpm 
> Verifying...                          ################################# [100%]
> Preparing...                          ################################# [100%]
>     package thinlinc-server-4.16.0-3491.x86_64 does not verify: no digest

* RHEL 9
    ✅ Signed RPM, not trusted key
        - We get a warning if the key is not trusted, but the RPM is installed
          successfully.
> warning: tl-4.16.0post-server/packages/thinlinc-server-4.16.0post-3537.x86_64.rpm: Header V4 RSA/SHA256 Signature, key ID 5e02d204: NOKEY
    ✅ Unsigned RPM
        - No warning.
    ❌ MD5 file digest (tl-4.16.0)
> [root@lab-23 ~]# rpm -ivh tl-4.16.0-server/packages/thinlinc-server-4.16.0-3491.x86_64.rpm 
> Verifying...                          ################################# [100%]
> Preparing...                          ################################# [100%]
>     package thinlinc-server-4.16.0-3491.x86_64 does not verify: no digest

Note that it was only the newer RHEL distros (8 and 9) that failed to install
our RPMs if they had MD5 file digests.

This is how FIPS mode was enabled on the distros:
[1] https://www.suse.com/support/kb/doc/?id=000019432
[2] * We did not succeed in enabling FIPS on CentOS 6.
[3] https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/security_guide/chap-federal_standards_and_regulations
[4] fips-mode-setup --enable
[5] fips-mode-setup --enable

Comment 14 Adam Halim 2024-03-28 09:13:34 CET

Tested client build 3435 on SLES 15 and RHEL 9 with FIPS mode enabled.

The client installed successfully on both platforms and worked without issue.

Comment 15 Samuel Mannehed 2024-03-28 16:31:38 CET

Verified that build 3541 of the ThinLinc server, and build 3438 of the client works well on fips-enabled CentOS 8 and fips-enabled Ubuntu 22.04:

Client tests:

✓ Install client
✓ Launch client
✓ Sound redirection
✓ Local drive redirection

Server tests:

✓ Install server
✓ tl-setup
✓ Connect using Web Access
✓ Browsing different pages in Web Admin
✓ Sound redirection using native client
✓ Local printing using native client
✗(*) Local drive redirection using native client

(*) Didn't work on CentOS 8, see bug 8331. Worked well on Ubuntu.

To enable fips on Ubuntu [1], I needed to get a Ubuntu Pro token.

[1]: https://ubuntu.com/security/certifications/docs/2204/fips

Comment 16 Samuel Mannehed 2024-04-04 12:45:25 CEST

I verified that fips was indeed enabled on the Ubuntu 22.04 machine mentioned in the previous comment:

> cendio@ubuntu-22:~$ cat /proc/sys/crypto/fips_enabled 
> 1
> cendio@ubuntu-22:~$ cat /proc/cmdline 
> BOOT_IMAGE=/boot/vmlinuz-5.15.0-101-fips root=UUID=66891745-0aec-4830-a1b6-18035a54e613 ro quiet splash fips=1

Comment 17 Samuel Mannehed 2024-04-04 12:45:46 CEST

The code changes also look good. Closing.