Change default authorizedkeys file

[otubo]

Proposed Commit Message

The following commit merged all ssh keys into a default user file
~/.ssh/authorized_keys in sshd_config had multiple files configured for
AuthorizedKeysFile:

commit f1094b1
Author: Eduardo Otubo otubo@redhat.com
Date: Thu Dec 5 17:37:35 2019 +0100

Multiple file fix for AuthorizedKeysFile config (#60)

This commit ignored the case when sshd_config would have a single file for
AuthorizedKeysFile, but a non default configuration, for example
~/.ssh/authorized_keys_foobar. In this case cloud-init would grab all keys
from this file and write a new one, the default ~/.ssh/authorized_keys
causing the bug.

rhbz: #1862967

Signed-off-by: Eduardo Otubo otubo@redhat.com

Additional Context

None

Test Steps

1. Prepare a VM with cloud-init enabled
2. Modify /etc/ssh/sshd_config to remove default .ssh/authorized_keys and change to another file e.g.:

# cat /etc/ssh/sshd_config | grep AuthorizedKeysFile
AuthorizedKeysFile .ssh/authorized_keys2

3. Remove /var/lib/cloud/instance/sem/config_ssh
4. systemctl restart cloud-init ; systemctl restart sshd
5. Try to ssh login through the cloud-init created user

Actual results:
Cannot login: Permission denied (publickey,gssapi-keyex,gssapi-with-mic)
The public key is written into .ssh/authorized_keys but not .ssh/authorized_keys2

Expected results:
Can login successfully. The public key is written into .ssh/authorized_keys2

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[otubo]

The commit that adapts the test cases also fixes the second test case test_multiple_authorizedkeys_file_order2 which was testing exact the same scenario as the first one.

[igalic]

unrelatedly, it's probably high time to retire DSA

[OddBloke]

This LGTM, and I've tested it locally. Thanks!