On Mon, Aug 12, 2013 at 4:23 PM, Thibault, Daniel
<[email protected]> wrote:
> -----Message d'origine-----
> Envoyé : 12 août 2013 16:11
>
> On Mon, Aug 12, 2013 at 9:23 AM, Thibault, Daniel 
> <[email protected]> wrote:
>> ----------------------------------------------------------------------
>>    Actually, a non-root user can also access the root daemon if he has sudo 
>> privileges.
>>
>>    The root daemon will see the various user-space events, but it will
>> *not* list the user sessions: the various lttng-sessiond daemons do
>> not talk to each other.  (This may become possible with a later
>> version of lttng)
>>
>>    To funnel all tracing through the root daemon, make sure any user 
>> lttng-sessiond daemons are killed and only the root lttng-sessiond daemon is 
>> running, then either make your users members of the 'tracing' group, or 
>> systematically use 'sudo lttng ...' or 'sudo -H lttng ...' from the user 
>> shells.  The first form will put the trace outputs in each user's 
>> ~/lttng-traces, the second form will combine all trace outputs in 
>> /root/lttng-traces.  You may need to chmod the resulting folders and files 
>> if you want to later access them as non-root.
>
> Keep in mind that in this scenario, setting up your traces as root (using 
> sudo) will still not let users that are not part of the 'tracing' group trace 
> their applications as no interactions with the session daemon are allowed; 
> that includes application registration.
>
> Getting around that would require that your users also launch the 
> applications themselves as root (using sudo) which is an unnecessary security 
> risk.
>
> Jérémie Galarneau
> EfficiOS Inc.
> -----Fin du message d'origine-----
>
>    I'm not sure I understand what you're getting at when you say "setting up 
> your traces as root (using sudo) will still not let users that are not part 
> of the 'tracing' group trace their applications as no interactions with the 
> session daemon are allowed; that includes application registration."  Users 
> that are not part of the 'tracing' group need take no special action to get 
> their apps traced: the root session daemon sees all user-spaces.

You're right. There seems to be an unrelated problem on my system. So,
to clarify:

- A root session daemon can only be controlled (e.g. create and modify
sessions) by root and members of the tracing group.
- Applications do not need to run as a member of the tracing group to be traced.

Jérémie

>
> Daniel U. Thibault
> Protection des systèmes et contremesures (PSC) | Systems Protection & 
> Countermeasures (SPC)
> Cyber sécurité pour les missions essentielles (CME) | Mission Critical Cyber 
> Security (MCCS)
> R & D pour la défense Canada - Valcartier (RDDC Valcartier) | Defence R&D 
> Canada - Valcartier (DRDC Valcartier)
> 2459 route de la Bravoure
> Québec QC  G3J 1X5
> CANADA
> Vox : (418) 844-4000 x4245
> Fax : (418) 844-4538
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> Gouvernement du Canada | Government of Canada
> <http://www.valcartier.drdc-rddc.gc.ca/>



-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com

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