Bug#977358: release-notes: document how to make the rescue mode usable if no root password is set (buster)
Andrei POPESCU wrote:
> Ok, here is something, just to get the discussion started:
Thanks! My suggestions below still need some work, but I'll call this
my first pass:
> The `rescue` boot option is unusable without a root password.
>
> If a password for the `root` account is not set the system will
> still ask for the root password if booted with the `rescue` option,
> effectively making the rescue mode unusable. In order to avoid this
> it is possible to boot using the kernel parameter
> `init=/sbin/sulogin --force`.
Simplifying:
<title>
The <literal>rescue</literal> boot option is unusable without a root password
</title>
<para>
Booting with the <literal>rescue</literal> option always requires
the root password. If one has not been set, this makes the rescue
mode effectively unusable. However it is still possible to boot
using the kernel parameter <literal>init=/sbin/sulogin --force</literal>
</para>
(I don't think "root" needs special markup; "rescue" only needs it
when we're talking about an untranslatable literal string).
(Should there be some hint here at the fact that this has happened
because we've switched to an implementation of sulogin without the
slightly dodgy Debian-specific patches?)
> To configure pkg:systemd to always to do the equivalent of this on
^^^ ^^ ^^
When we're talking about machines booting with systemd-sysv, we should
avoid mentioning <systemitem role="package">systemd</systemitem>
(which is a pain to type anyway).
The "to" might go in either position, but not both. Here perhaps we
might be better off saying
To configure systemd to do the equivalent of this whenever the
<literal>rescue</literal> option is used,
> selecting the `rescue` option add `SYSTEMD_SULOGIN_FORCE=1` to the
> Environment of the rescue.service unit (see
> file:/usr/share/doc/systemd/ENVIRONMENT.md.gz). The `rescue.service`
At least this information is already on my system before the
dist-upgrade.
> unit is started by pkg:systemd in case it detects `single` in the
^^^^^^^
> kernel command line (see man:systemd).
Bad use of "in case" - most English-speakers interpret "in case of" as
"unconditionally, to avert the danger of".
systemd(1) defines "single" and "rescue" (and "1"!) as aliases of
"systemd.unit=rescue.target", so maybe we can make that clearer
earlier.
<para>
To configure systemd to do the equivalent of this whenever it
boots into rescue mode (also known as single mode - see <ulink
url="&url-man;/bullseye/systemd/systemd.1.html">systemd(1)</ulink>),
add <literal>SYSTEMD_SULOGIN_FORCE=1</literal> to the
Environment of the <literal>rescue.service</literal> unit (see
<filename>/usr/share/doc/systemd/ENVIRONMENT.md.gz</filename>).
</para>
Unfortunately we also need readers to know
* how to add things to a systemd unit (we don't want people editing
/lib/systemd/system/rescue.service and losing it in an upgrade)
* how much of the rest of the file they should copy (as little as
possible, I think, but how much is that?)
* how the syntax for multiple items in an Environment= line works
This probably needs an external link, but I'm not optimistic we'll
find one. Maybe this is another case where we'll need a dedicated
page on wiki.debian.org.
(And why *is* the systemd man page in section 1, anyway? Shouldn't it
be in section 8, like systemv init used to be?)
> It might be useful to do the same for the `emergency.service` unit
> (or instead) which is started ''automatically'' in case of certain
^^^^^^^^^^ ^^^^^^^^^^
> errors (see man:systemd.special), or if `emergency` is added to the
> kernel command line (e.g. in case the system can't be recovered by
^^^^^^^
> using the `rescue` mode).
"The same or instead" needs to be reorganised as "as well or instead".
One of those "in case"s almost works.
I'm not sure what markup you mean for ''automatically''.
<para>
It might be useful to do this for the <literal>emergency.service</literal>
unit (as well or instead), which is started automatically in the case
of certain errors (see <ulink
url="&url-man;/bullseye/systemd/systemd.special.7.html">systemd.special(7)</ulink>),
or if <literal>emergency</literal> is added to the kernel command line
(e.g. if the system can't be recovered by using the rescue mode).
</para>
(Why *did* setting these systems up with passwords in the first place
go out of fashion?)
> For background and a discussion on the security implications see
> bts:802211.
I forget if we've got special markup for this or whether we just say
<para>
For background and a discussion on the security implications see
<ulink url="https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=802211";>bug
#802211</ulink>.
</para>
Or even delegate it to the wiki link. Oh well, buster needed two
last-minute wiki pages for complicated issues, so if bullseye only
needs one for this we'll still be improving...
--
JBR with qualifications in linguistics, experience as a Debian
sysadmin, and probably no clue about this particular package
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