openssh unix dev - Jun 2020 - "ssh -Q key" does not list rsa-sha2 algorithms

With the upcoming deprecation of ssh-rsa I was trying to see what keys my
version of OpenSSH ( 7.8p1 ) supports. I noticed that "ssh -Q key"
does not
actually list the suggested algorithms to transition to ( rsa-sha2-256 and
rsa-sha2-512 ) even though they are supported. Looking through the code, it
looks like an issue with the arguments passed to sshkey_alg_list in ssh.c
where it should be as below:

        case 'Q':
            cp = NULL;
            if (strcmp(optarg, "cipher") == 0)
                cp = cipher_alg_list('\n', 0);
            else if (strcmp(optarg, "cipher-auth") == 0)
                cp = cipher_alg_list('\n', 1);
            else if (strcmp(optarg, "mac") == 0)
                cp = mac_alg_list('\n');
            else if (strcmp(optarg, "kex") == 0)
                cp = kex_alg_list('\n');
            else if (strcmp(optarg, "key") == 0)
-                cp = sshkey_alg_list(0, 0, 0, '\n');
+               cp = sshkey_alg_list(0, 0, 1, '\n');

is that right? I validated that the same code exists in HEAD as of this
morning. If so it should be a pretty simple bugfix I would be happy to make
or to let someone else from the dev team make if they have a spare moment.

It's totally a minor quality-of-life issue for understanding algorithms
supported compared to the other threads I saw about corner cases where the
rsa-sha2 family of algos is not used during negotiation, but I can
understand how this happens. The sshkey_alg_list call has the first 2 flags
be excluding bools ( set it to true to limit things ) whereas the third one
is an inclusive bool ( set it to true to include things ).

To close, love openssh, love the work the team does, just doing some minor
nitpicking :-)

Cheers,

Ethan

On 2020-06-01, Ethan Rahn <ethan.rahn at gmail.com> wrote:
> With the upcoming deprecation of ssh-rsa I was trying to see what keys my
> version of OpenSSH ( 7.8p1 ) supports. I noticed that "ssh -Q
key" does not
> actually list the suggested algorithms to transition to ( rsa-sha2-256 and
> rsa-sha2-512 ) even though they are supported.
"-Q key" are the supported key formats.  For the signature algorithms,
you want "-Q sig".  This is documented in the man page.

-- 
Christian "naddy" Weisgerber                          naddy at
mips.inka.de

On Tue, 2 Jun 2020 at 06:12, Christian Weisgerber <naddy at mips.inka.de>
wrote
> On 2020-06-01, Ethan Rahn <ethan.rahn at gmail.com> wrote:
>
> > With the upcoming deprecation of ssh-rsa I was trying to see what keys
my
> > version of OpenSSH ( 7.8p1 ) supports. I noticed that "ssh -Q
key" does not
> > actually list the suggested algorithms to transition to ( rsa-sha2-256
and
> > rsa-sha2-512 ) even though they are supported.
>
> "-Q key" are the supported key formats.  For the signature
algorithms,
> you want "-Q sig".  This is documented in the man page.
In addition, from version 8.2 ssh -Q will also accept ssh_config
keywords and emit the formats or algorithms accepted by that keyword,
eg.

$ ssh -V
OpenSSH_8.2p1, OpenSSL 1.1.1g FIPS  21 Apr 2020

$ ssh -Q PubkeyAcceptedKeyTypes
[...]
ssh-rsa
rsa-sha2-256
rsa-sha2-512
[...]

-- 
Darren Tucker (dtucker at dtucker.net)
GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860  37F4 9357 ECEF 11EA A6FA (new)
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

Il 1 giugno 2020 22:04:43 CEST, Christian Weisgerber <naddy at
mips.inka.de> ha scritto:
>"-Q key" are the supported key formats.  For the signature
algorithms,
>you want "-Q sig".  This is documented in the man page.
Listed starting from which version?

Latest man referred online
https://man.openbsd.org/sshd_config
Doesn't show it, right?

Btw, you are referring to:
https://man.openbsd.org/sshd_config#CASignatureAlgorithms
Right?

Thanks,
Daniele