Subject: Pasword expiration warning

From: Gilles Darold <[email-masked]>
Date: Fri, 19 Nov 2021 15:49:37 +0100

Hi all,

Now that the security policy is getting stronger, it is not uncommon to 
create users with a password expiration date (VALID UNTIL). The problem 
is that the user is only aware that his password has expired when he can 
no longer log in unless the application with which he is connecting 
notifies him beforehand.

I'm wondering if we might be interested in having this feature in psql? 
For example for a user whose password expires in 3 days:

gilles=# CREATE ROLE foo LOGIN PASSWORD 'foo' VALID UNTIL '2021-11-22';
CREATE ROLE
gilles=# \c - foo
Password for user foo:
psql (15devel, server 14.1 (Ubuntu 14.1-2.pgdg20.04+1))
** Warning: your password expires in 3 days **
You are now connected to database "gilles" as user "foo".

My idea is to add a psql variable that can be defined in psqlrc to 
specify the number of days before the user password expires to start 
printing a warning. The warning message is only diplayed in interactive 
mode Example:

$ cat /etc/postgresql-common/psqlrc
\set PASSWORD_EXPIRE_WARNING 7

Default value is 0 like today no warning at all.

Of course any other client application have to write his own beforehand 
expiration notice but with psql we don't have it for the moment. If 
there is interest for this psql feature I can post the patch.

-- 
Gilles Darold

---

From: Dinesh Chemuduru <[email-masked]>
Date: Fri, 19 Nov 2021 20:46:29 +0530

On Fri, 19 Nov 2021 at 20:19, Gilles Darold <[email-masked]> wrote:

> is that the user is only aware that his password has expired when he can no
> longer log in unless the application with which he is connecting notifies
> him beforehand.
>
>
> I'm wondering if we might be interested in having this feature in psql? For
> example for a user whose password expires in 3 days:
>
> My idea is to add a psql variable that can be defined in psqlrc to specify
> the number of days before the user password expires to start printing a
> warning. The warning message is only diplayed in interactive mode Example:
>
> +1

It is useful to notify the users about their near account expiration,
and we are doing that at client level.

>
>
> Of course any other client application have to write his own beforehand expiration
> notice but with psql we don't have it for the moment. If there is interest
> for this psql feature I can post the patch.
>
> --
> Gilles Darold
>
>

---

From: Tom Lane <[email-masked]>
Date: Fri, 19 Nov 2021 10:55:34 -0500

Gilles Darold <[email-masked]> writes:
> create users with a password expiration date (VALID UNTIL).

TBH, I thought people were starting to realize that forced password
rotations are a net security negative.  It's true that a lot of
places haven't gotten the word yet.

> I'm wondering if we might be interested in having this feature in psql? 

This proposal kind of seems like a hack, because
(1) not everybody uses psql
(2) psql can't really tell whether rolvaliduntil is relevant.
    (It can see whether the server demanded a password, but
    maybe that went to LDAP or some other auth method.)

That leads me to wonder about server-side solutions.  It's easy
enough for the server to see that it's used a password with an
expiration N days away, but how could that be reported to the
client?  The only idea that comes to mind that doesn't seem like
a protocol break is to issue a NOTICE message, which doesn't
seem like it squares with your desire to only do this interactively.
(Although I'm not sure I believe that's a great idea.  If your
application breaks at 2AM because its password expired, you
won't be any happier than if your interactive sessions start to
fail.  Maybe a message that would leave a trail in the server log
would be best after all.)

> Default value is 0 like today no warning at all.

Off-by-default is pretty much guaranteed to not help most people.

			regards, tom lane

---

From: Gilles Darold <[email-masked]>
Date: Fri, 19 Nov 2021 17:56:20 +0100

> (1) not everybody uses psql

Yes, for me it's a comfort feature. When a user connect to a PG backend 
using an account that have expired you have no information that the 
problem is a password expiration. The message returned to the user is 
just: "FATAL: password authentication failed for user "foo".  We had to 
verify in the log file that the problem is related to "DETAIL:  User 
"foo" has an expired password.".  If the user was warned beforehand to 
change the password it will probably saves me some time.

>      maybe that went to LDAP or some other auth method.)

I agree, I hope that in case of external authentication rolvaliduntil is 
not set and in this case I guess that there is other notification 
channels to inform the user that his password will expire. Otherwise yes 
the warning message could be a false positive but the rolvaliduntil can 
be changed to infinity to fix this case.

> would be best after all.)

I think that this is the responsibility of the client to display a 
warning when the password is about to expire, the backend could help the 
application by sending a NOTICE but the application will still have to 
report the notice. I mean that it can continue to do all the work to 
verify that the password is about to expire.

> Off-by-default is pretty much guaranteed to not help most people.

Right, I was thinking of backward compatibility but this does not apply 
here. So default to 7 days will be better.

To sum up as I said on top this is just a comfort notification dedicated 
to psql and for local pg account to avoid looking at log file for 
forgetting users.

-- 
Gilles Darold

---

From: "Bossart, Nathan" <[email-masked]>
Date: Sat, 20 Nov 2021 00:17:53 +0000

> would be best after all.)

I bet it's possible to use the ClientAuthentication_hook for this.  In
any case, I agree that it probably belongs server-side so that other
clients can benefit from this.

Nathan

---

From: Michael Paquier <[email-masked]>
Date: Sat, 20 Nov 2021 14:46:02 +0900

> clients can benefit from this.

ClientAuthentication_hook is called before the user is informed of the
authentication result, FWIW, so that does not seem wise.
--
Michael

---

From: Andrew Dunstan <[email-masked]>
Date: Sat, 20 Nov 2021 08:48:35 -0500

> clients can benefit from this.

+1 for a server side solution. The people most likely to benefit from
this are the people least likely to be using psql IMNSHO.

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

---

From: Gilles Darold <[email-masked]>
Date: Sun, 21 Nov 2021 10:49:57 +0100

> this are the people least likely to be using psql IMNSHO.

Ok, I can try to implement something at server side using a NOTICE message.

-- 
Gilles Darold