Re: Setuid programs

["Gábor Boskovits" <boskovits@gmail.com>]

Hello,

Christopher Lemmer Webber <cwebber@dustycloud.org> ezt írta (időpont:
2020. szept. 9., Sze, 21:00):
>
> Maxim Cournoyer writes:
>
> > Hello Gabor!
> >
> > Gábor Boskovits <boskovits@gmail.com> writes:
> >
> >> Hello guix,
> >>
> >> I would like to propose an extension to how setuid programs are
> >> currently handled. The last time I checked it could only do setuid and
> >> setgid root. Some services, such as postfix need a more fine grained
> >> setuid setup. I would propose a record type, such as:
> >> (setuid
> >> (program setuid-program)
> >> (setuid setuid-setuid)
> >> (setgid setuid-setgid)
> >> (user setuid-user)
> >> (group setuid-group))
> >>
> >> So that there is more fine grained control.
> >>
> >> I would also propose to move this to the services framework, so that
> >> services could extend this field on demand.
> >>
> >> Wdyt?
> >
> > This sounds great!  I also encountered such limitation and tried to
> > fixing it in https://issues.guix.info/41763, with some success (and an
> > unresolved limitation pointed by Chriistopher) but I agree that using a
> > record makes more sense and is more future proof.
> >
> > Maxim
>
> I'm eager to use Postfix on Guix (maybe it's me, but I just can't make
> sense of the weird DSL that opensmtpd uses) so I guess if that's what's
> necessary it already makes it a good idea.
>
> However I don't fully understand the syntax of what you proposed.  Let's
> see if I can guess with a fake entry
>
> #~(setuid
>    ;; The program to run, from the shady package
>    (program (string-append #$shady "/bin/scaryfoo")
>    ;; Would this be a boolean?  If so should it be `setuid?`
yes, this should be a bool, studi? looks good to me.
>    (setuid setuid-setuid)
>    ;; Likewise?
>    (setgid setuid-setgid)
yes, the same thing applies here.
>    ;; Presumably the use we want to set this to
>    (user setuid-user)
yes, this should just be the uid of the owner
>    ;; Presumably the group we want to se this to
this should be the gid.
>    (group setuid-group))
>
> ... right?
>
> I guess this could be done in a backwards compatible way;
> %setuid-programs could either evaluate to strings or records, so the
> "simpler" version can remain an option?
Yes, it can be done this way. Actually I had a bit more general
solution in mind,
I feel there should be service to install a file from a store to a
given place, and with all the access control available,
like acl-s, if supported. And then provide the whole setuid thing as a
backwards compatibility layer, somehow like you described.
For now I guess creating this record type and implementing the
extended setuid functionality would be a good first step.
>
>  - Chris
Best regards,
g_bor
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