sshd boolean option parsing is excessively case-sensitive

Bug #1656557 reported by nmarques on 2017-01-14
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
portable OpenSSH
Unknown
Unknown
openssh (Ubuntu)
Low
Unassigned

Bug Description

Dear People,

The field 'PasswordAuthentication' unlike all the others requires no capitalization in order for the ssh daemon to start properly!

While this works:

PasswordAuthentication yes

The following doesn't work for this field (though works for other fields):

PasswordAuthentication Yes

This is most likely an issue to bring up to upstream project. Could we have a fix so that configuration can be done in a consistent way and the daemon doesn't break because of capitalization of a given parameter (it works on the other fields using [Yy] or [Nn]).

This is a reality in 14.04 and 16.04.

Thanks for your time.

Colin Watson (cjwatson) wrote :

This is true of all the purely yes/no flags; I agree that there are some multi-state options that behave differently.

I've raised this upstream, and linked the bug here. Thanks for your report. I should warn you in advance that a backport to 14.04/16.04 is rather unlikely, but if fixed upstream then it'll make its way into later Ubuntu releases.

summary: - sshd_config issue crashes sshd daemon
+ sshd boolean option parsing is excessively case-sensitive
Colin Watson (cjwatson) on 2017-01-15
Changed in openssh (Ubuntu):
status: New → Triaged
importance: Undecided → Low
nmarques (nmo-marques) wrote :

Hi Collin, thanks for the input. I've spoken to upstream also about this, and they informed me that some options are parsed with a more advanced parser than others (the last being yes/no).

Their advice was to follow the comments spec.

Launchpad Janitor (janitor) wrote :

This bug was fixed in the package openssh - 1:7.7p1-2

---------------
openssh (1:7.7p1-2) unstable; urgency=medium

  * Fix parsing of DebianBanner option (closes: #894730).

 -- Colin Watson <email address hidden> Wed, 04 Apr 2018 00:47:29 +0100

Changed in openssh (Ubuntu):
status: Triaged → Fix Released
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