bug#38198: closed (missing shell for postgresql system user)

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Your message dated Thu, 14 Nov 2019 11:02:15 +0100
with message-id <address@hidden>
and subject line Re: bug#38198: missing shell for postgresql system user
has caused the debbugs.gnu.org bug report #38198,
regarding missing shell for postgresql system user
to be marked as done.

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38198: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=38198
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--- Begin Message --- Subject: missing shell for postgresql system user Date: Wed, 13 Nov 2019 18:36:52 +0100

Hello Guix!

Current postgresql access rules (pg_hba.conf) defaults to (see
[bug#36191] for details on that patch):

--8<---------------cut here---------------start------------->8---
local   all     all                     peer
host    all     all     127.0.0.1/32    md5
host    all     all     ::1/128         md5
--8<---------------cut here---------------end--------------->8---

Peer authentication works by obtaining the (local) client's operating
system user name from the kernel and using it as the allowed database
user name, and is better than "trust" authentication

To access a database server on localhost for the first time as the user
postgres (the superuser) a person should use:

--8<---------------cut here---------------start------------->8---
sudo su postgres -c 'psql'
--8<---------------cut here---------------end--------------->8---

AFAIK this is the only method available after database initialization,
with peer authentication

Since the postgres user currently have a nologin shell (from
gnu/services/databases.scm):

--8<---------------cut here---------------start------------->8---
(define %postgresql-accounts
  (list (user-group (name "postgres") (system? #t))
        (user-account
         (name "postgres")
         (group "postgres")
         (system? #t)
         (comment "PostgreSQL server user")
         (home-directory "/var/empty")
         (shell (file-append shadow "/sbin/nologin")))))
--8<---------------cut here---------------end--------------->8---

the above command does not work

As a workaround I changed the postgres user shell to <store>/bin/bash
and I was able to connect

I do not see any security issue giving a shell to postgres, since it's
password is disabled in /etc/shadow so the only way to access as
postgres is via `sudo su postgres`

Thougts?

Thanks, Gio'

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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--- Begin Message --- Subject: Re: bug#38198: missing shell for postgresql system user Date: Thu, 14 Nov 2019 11:02:15 +0100

Hello Gábor,

Gábor Boskovits <address@hidden> writes:

[...]

>> To access a database server on localhost for the first time as the user
>> postgres (the superuser) a person should use:
>>
>> --8<---------------cut here---------------start------------->8---
>> sudo su postgres -c 'psql'
>> --8<---------------cut here---------------end--------------->8---

[...]

> I would not mind this change, I think it is ok. However it is easy to
> work around this with su -s.
> I usually do that.

Oh, that's the real solution: thanks! (I should study more...)

  sudo su postgres -s psql

Since giving a shell to the postgres user is **not** the solution, I'm
closing this bug.

I'll try to send a patch to the relevant documentation in the manual,
since now that we changed "trust" to "peer" a regular user cannot
connect to a newly initialized database using `psql -U postgres` (and is
good for security reasons); the user must be part of the "wheel" group
(or be authorized via sudoers in other ways) to be able to use `sudo su
postgres -s psql`

[...]

Thanks! Gio'

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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