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Re: access to /proc/pid/maps

To: Martins Innus <minnus@xxxxxxxxxxx>
Subject: Re: access to /proc/pid/maps
From: fche@xxxxxxxxxx (Frank Ch. Eigler)
Date: Tue, 02 Jul 2013 17:34:16 -0400
Cc: pcp@xxxxxxxxxxx
Delivered-to: pcp@xxxxxxxxxxx
In-reply-to: <51D3282C.3060806@xxxxxxxxxxx> (Martins Innus's message of "Tue, 02 Jul 2013 15:21:16 -0400")
References: <51D3282C.3060806@xxxxxxxxxxx>
User-agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux)
Hi -

minnus wrote:

>     We've just noticed that with recent versions of pcp that run as
> non-root, we've lost access to the /proc/pid/maps information. [...]

As background, several months ago, proc_linux PMDA was removed from
the default pmcd/pmda suite because it exposed sensitive information
about processes to the network.  The separated PMDA could be
hand-enabled, but as you notice, when running as a DSO within PMCD in
uid=pcp mode, only a relatively unprivileged subset of information is
available.

The impending default solution to this is the pmcd
authenticated-connection mode, wherein a pcp client can forward user
identity to pmcd, after which the pmda-linux code can setuid to that
user temporarily to service proc requests.  The new AF_UNIX pmcd
transport will pass credentials automatically.  That should handle
users being able to monitor their own processes, or root monitoring
everyone, without having to run pmcd itself as root.

- FChE

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