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Re: PCP Updates: pmlogger AF_UNIX socket for normal users; qa version ch

To: "Frank Ch. Eigler" <fche@xxxxxxxxxx>, Dave Brolley <brolley@xxxxxxxxxx>
Subject: Re: PCP Updates: pmlogger AF_UNIX socket for normal users; qa version check bump
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Thu, 6 Mar 2014 03:13:16 -0500 (EST)
Cc: pcp@xxxxxxxxxxx
Delivered-to: pcp@xxxxxxxxxxx
In-reply-to: <y0ma9d4e93m.fsf@xxxxxxxx>
References: <53075D46.6090807@xxxxxxxxxx> <1734063835.17483667.1393481715436.JavaMail.zimbra@xxxxxxxxxx> <53175AAC.5050706@xxxxxxxxxx> <y0ma9d4e93m.fsf@xxxxxxxx>
Reply-to: Nathan Scott <nathans@xxxxxxxxxx>
Thread-index: JbVHvMuVMG1qMKWNMGiTI1XDBRk5Hw==
Thread-topic: PCP Updates: pmlogger AF_UNIX socket for normal users; qa version check bump

----- Original Message -----
> 
> brolley wrote:
> 
> 
> > [...]
> >          [access]
> >         -disallow * : all;
> >         -allow localhost : enquire;
> >         +disallow .* : all;
> >         +disallow :* : all;
> >         +allow local:* : enquire;
> > [...]
> 
> That is a drastic change, by the way, removing "enquire" powers from
> localhost.  (We should open a bug to remind ourselves to fix the

Indeed, it is probably too big a risk for a point release I think,
given its the likely (root) cause of that test system failing to
start pmlogger after an upgrade with an existing config.

> pmlogger bug that allows mutation operations to be triggered at the
> pmlc-enquire privilege, as discussed on IRC.)
> 
> > This code tries to make sure that pmlogger is running by attempting to
> > connect
> > using pmlc. Without the updated access controls, pmlogger correctly rejects
> > each connection attempt [...]

That'd be a bug, for people on the point-release-upgrade path.  But...

> While you were away last week, we were talking about ACL enforcement
> options for the AF_UNIX link.  Because of world-readable directories,
> a default that prohibits localhost but permits local: (AF_UNIX)
> doesn't give us any additional security.

[ It does give us the option of moving away from a network accessible
socket (perhaps via command line flag), removing all remote exploit
possibilities - which is some additional security I guess. ]

>  We really need to use
> AF_UNIX's credential-passing facility.
> 
> Where is the "local:*" part of that ACL documented, by the way?  Can
> we teach it something like:
> 
> local:uid    /* to mean same-uid as pmlogger */
> local:gid    /* to mean same-gid as pmlogger */

But same-uid/gid should always be able to connect & have full access
permissions; in which case, this whole problem goes away (AFAICT) and
we have a safe upgrade path.  Simpler code & configuration files too.
Is there any reason to not allow same-uid/gid full access?

cheers.

--
Nathan

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