Setting loginuid for a process starting at boot

Setting loginuid for a process starting at boot

[Maupertuis Philippe]

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Hi,
I want to monitor a process which starts at boot.
I would like to assign  it a specific loginuid for that purpose.
What is the best way to do that ?

Regards
Philippe

________________________________

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Re: Setting loginuid for a process starting at boot

[Eric Paris]

On Sun, 2014-01-12 at 23:00 +0100, Maupertuis Philippe wrote:
> Hi,
> 
> I want to monitor a process which starts at boot.
> 
> I would like to assign  it a specific loginuid for that purpose.
> 
> What is the best way to do that ?

Have the init script echo a value into /proc/self/loginuid ?

Re: Setting loginuid for a process starting at boot

[Steve Grubb]

On Monday, January 13, 2014 03:12:55 PM Eric Paris wrote:
> On Sun, 2014-01-12 at 23:00 +0100, Maupertuis Philippe wrote:
> > Hi,
> > 
> > I want to monitor a process which starts at boot.
> > 
> > I would like to assign  it a specific loginuid for that purpose.
> > 
> > What is the best way to do that ?
> 
> Have the init script echo a value into /proc/self/loginuid ?

The loginuid is supposed to be used only for real user sessions. The daemon 
would not normally qualify as a user session. I suspect that this is needed 
because we have no way to audit by process name. I suspect that is the real 
issue that leads to needing to use the loginuid for something it was not 
intended for.

-Steve

RE : Setting loginuid for a process starting at boot

[Maupertuis Philippe]

The process listens on a network port. It receives custom commands that are executed on the server.
Only one remote host can communicate with the host, the user identifies himself on the remote host only.
The goal is to allow the user to run  the same scripts  on a  lot of server in one command.

Please don't tell me it's silly or insecure or that softwares exist to do that in a secure  way.
I would like to be able to at least monitor what happend throughthis channel.
That means the listening process and all its childs where the valuable changes to the system are made.
It's why I was thinking of setting a dedicated loginuid.

Maybe, eventually it would turn in a PAM-aware application with a proper user authentication and my problems will be solved.

If a simple echo does the trick what is the use of audit_setloginuid or pam_loginuid ?
Any root script can defeat audit with a single command.
I am gobsmacked !
I hope I missed something.

Philippe
________________________________________
De : Steve Grubb [sgrubb@redhat.com]
Date d'envoi : lundi 13 janvier 2014 21:16
À : linux-audit@redhat.com
Cc : Eric Paris; Maupertuis Philippe
Objet : Re: Setting loginuid for a process starting at boot

On Monday, January 13, 2014 03:12:55 PM Eric Paris wrote:
> On Sun, 2014-01-12 at 23:00 +0100, Maupertuis Philippe wrote:
> > Hi,
> >
> > I want to monitor a process which starts at boot.
> >
> > I would like to assign  it a specific loginuid for that purpose.
> >
> > What is the best way to do that ?
>
> Have the init script echo a value into /proc/self/loginuid ?

The loginuid is supposed to be used only for real user sessions. The daemon
would not normally qualify as a user session. I suspect that this is needed
because we have no way to audit by process name. I suspect that is the real
issue that leads to needing to use the loginuid for something it was not
intended for.

-Steve


Ce message et les pièces jointes sont confidentiels et réservés à l'usage exclusif de ses destinataires. Il peut également être protégé par le secret professionnel. Si vous recevez ce message par erreur, merci d'en avertir immédiatement l'expéditeur et de le détruire. L'intégrité du message ne pouvant être assurée sur Internet, la responsabilité de Worldline ne pourra être recherchée quant au contenu de ce message. Bien que les meilleurs efforts soient faits pour maintenir cette transmission exempte de tout virus, l'expéditeur ne donne aucune garantie à cet égard et sa responsabilité ne saurait être recherchée pour tout dommage résultant d'un virus transmis.

This e-mail and the documents attached are confidential and intended solely for the addressee; it may also be privileged. If you receive this e-mail in error, please notify the sender immediately and destroy it. As its integrity cannot be secured on the Internet, the Worldline liability cannot be triggered for the message content. Although the sender endeavours to maintain a computer virus-free network, the sender does not warrant that this transmission is virus-free and will not be liable for any damages resulting from any virus transmitted.

Re: Setting loginuid for a process starting at boot

[Steve Grubb]

On Monday, January 13, 2014 10:17:43 PM Maupertuis Philippe wrote:
> The process listens on a network port. It receives custom commands that are
> executed on the server. Only one remote host can communicate with the host,
> the user identifies himself on the remote host only. The goal is to allow
> the user to run  the same scripts  on a  lot of server in one command.

OK, then it sounds like you have an entry point daemon and it should be 
setting the loginuid.


> Please don't tell me it's silly or insecure or that softwares exist to do
> that in a secure  way. I would like to be able to at least monitor what
> happend throughthis channel. That means the listening process and all its
> childs where the valuable changes to the system are made. It's why I was
> thinking of setting a dedicated loginuid.
> 
> Maybe, eventually it would turn in a PAM-aware application with a proper
> user authentication and my problems will be solved.
> 
> If a simple echo does the trick what is the use of audit_setloginuid or
> pam_loginuid ? 

They hide the implementation details in case it changes someday.

>Any root script can defeat audit with a single command.

There are restrictions (fs/proc/base.c). You can only set the loginuid on 
yourself.

> I am gobsmacked !
> I hope I missed something.

And besides, any root process can run auditctl -e 0 and disable the audit 
system (unless it was marked immutable).

-Steve

RE: Setting loginuid for a process starting at boot

[Maupertuis Philippe]

Auditctl -e wont probably go unnoticed while an inconspicuous echo probably would.
Is there a rule to track this action without overloading the system ?
Alternatively, is a post mortem analysis viable ?
I was thinking of finding process in the audit.log whose loginuid differs from parent's loginuid.
Is there a way to extract information and reformat the result (to keep process pid ppid loginuid for example) ?

Philippe

-----Message d'origine-----
De : Steve Grubb [mailto:sgrubb@redhat.com]
Envoyé : lundi 13 janvier 2014 23:06
À : Maupertuis Philippe
Cc : linux-audit@redhat.com
Objet : Re: Setting loginuid for a process starting at boot


On Monday, January 13, 2014 10:17:43 PM Maupertuis Philippe wrote:
> The process listens on a network port. It receives custom commands
> that are executed on the server. Only one remote host can communicate
> with the host, the user identifies himself on the remote host only.
> The goal is to allow the user to run  the same scripts  on a  lot of server in one command.

OK, then it sounds like you have an entry point daemon and it should be setting the loginuid.


> Please don't tell me it's silly or insecure or that softwares exist to do
> that in a secure  way. I would like to be able to at least monitor what
> happend throughthis channel. That means the listening process and all its
> childs where the valuable changes to the system are made. It's why I was
> thinking of setting a dedicated loginuid.
>
> Maybe, eventually it would turn in a PAM-aware application with a proper
> user authentication and my problems will be solved.
>
> If a simple echo does the trick what is the use of audit_setloginuid or
> pam_loginuid ?

They hide the implementation details in case it changes someday.

>Any root script can defeat audit with a single command.

There are restrictions (fs/proc/base.c). You can only set the loginuid on
yourself.

> I am gobsmacked !
> I hope I missed something.

And besides, any root process can run auditctl -e 0 and disable the audit
system (unless it was marked immutable).

-Steve


Ce message et les pièces jointes sont confidentiels et réservés à l'usage exclusif de ses destinataires. Il peut également être protégé par le secret professionnel. Si vous recevez ce message par erreur, merci d'en avertir immédiatement l'expéditeur et de le détruire. L'intégrité du message ne pouvant être assurée sur Internet, la responsabilité de Worldline ne pourra être recherchée quant au contenu de ce message. Bien que les meilleurs efforts soient faits pour maintenir cette transmission exempte de tout virus, l'expéditeur ne donne aucune garantie à cet égard et sa responsabilité ne saurait être recherchée pour tout dommage résultant d'un virus transmis.

This e-mail and the documents attached are confidential and intended solely for the addressee; it may also be privileged. If you receive this e-mail in error, please notify the sender immediately and destroy it. As its integrity cannot be secured on the Internet, the Worldline liability cannot be triggered for the message content. Although the sender endeavours to maintain a computer virus-free network, the sender does not warrant that this transmission is virus-free and will not be liable for any damages resulting from any virus transmitted.

Re: Setting loginuid for a process starting at boot

[Steve Grubb]

On Tuesday, January 14, 2014 02:13:45 PM Maupertuis Philippe wrote:
> Auditctl -e wont probably go unnoticed while an inconspicuous echo probably
> would.

Both are auditable events as required by common criteria. Changes to auditing 
must produce an event as well as the assignment of loginuids. This is 
automatic and not caused by a rule.

> Is there a rule to track this action without overloading the system?

Changes to audit state are auditable events. You can test this yourself with 
auditctl and ausearch.


> Alternatively, is a post mortem analysis viable ?

yes.


> I was thinking of finding process in the audit.log whose loginuid differs
> from parent's loginuid. Is there a way to extract information and reformat
> the result (to keep process pid ppid loginuid for example) ?

You can write a utility using the auparse library to do anything you want it 
to do.

https://fedorahosted.org/audit/browser/trunk/tools/aulastlog/aulastlog.c

The aulastlog program is probably a decent starting point to create something 
like this. Instead of keeping uid, you'd be keeping pids and some attributes 
of them. My guess is that you'll have long running processes that are not in 
the logs and you'll have some unknowns.

-Steve

RE: Setting loginuid for a process starting at boot

[Maupertuis Philippe]

Thank you so much for your very valuable answers.
After playing around, I found that the assignment of loginuid  produces a login type message (I could have guess)

Where can I find the description and the trigger of all messages types if such a documentation exists ?

Philippe

-----Message d'origine-----
De : Steve Grubb [mailto:sgrubb@redhat.com]
Envoyé : mardi 14 janvier 2014 15:34
À : Maupertuis Philippe
Cc : linux-audit@redhat.com
Objet : Re: Setting loginuid for a process starting at boot


On Tuesday, January 14, 2014 02:13:45 PM Maupertuis Philippe wrote:
> Auditctl -e wont probably go unnoticed while an inconspicuous echo
> probably would.

Both are auditable events as required by common criteria. Changes to auditing must produce an event as well as the assignment of loginuids. This is automatic and not caused by a rule.

> Is there a rule to track this action without overloading the system?

Changes to audit state are auditable events. You can test this yourself with auditctl and ausearch.


> Alternatively, is a post mortem analysis viable ?

yes.


> I was thinking of finding process in the audit.log whose loginuid differs
> from parent's loginuid. Is there a way to extract information and reformat
> the result (to keep process pid ppid loginuid for example) ?

You can write a utility using the auparse library to do anything you want it
to do.

https://fedorahosted.org/audit/browser/trunk/tools/aulastlog/aulastlog.c

The aulastlog program is probably a decent starting point to create something
like this. Instead of keeping uid, you'd be keeping pids and some attributes
of them. My guess is that you'll have long running processes that are not in
the logs and you'll have some unknowns.

-Steve


Ce message et les pièces jointes sont confidentiels et réservés à l'usage exclusif de ses destinataires. Il peut également être protégé par le secret professionnel. Si vous recevez ce message par erreur, merci d'en avertir immédiatement l'expéditeur et de le détruire. L'intégrité du message ne pouvant être assurée sur Internet, la responsabilité de Worldline ne pourra être recherchée quant au contenu de ce message. Bien que les meilleurs efforts soient faits pour maintenir cette transmission exempte de tout virus, l'expéditeur ne donne aucune garantie à cet égard et sa responsabilité ne saurait être recherchée pour tout dommage résultant d'un virus transmis.

This e-mail and the documents attached are confidential and intended solely for the addressee; it may also be privileged. If you receive this e-mail in error, please notify the sender immediately and destroy it. As its integrity cannot be secured on the Internet, the Worldline liability cannot be triggered for the message content. Although the sender endeavours to maintain a computer virus-free network, the sender does not warrant that this transmission is virus-free and will not be liable for any damages resulting from any virus transmitted.

Re: Setting loginuid for a process starting at boot

[Steve Grubb]

On Tuesday, January 14, 2014 04:55:30 PM Maupertuis Philippe wrote:
> Where can I find the description and the trigger of all messages types if
> such a documentation exists ?

To some extent, the documentation is in the header files. They describe what
the intended use is for the event record types.

https://fedorahosted.org/audit/browser/trunk/lib/libaudit.h#L40
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/include/uapi/linux/audit.h?id=refs/tags/v3.12.7#n30

As for what triggers them, it can mostly be deduced from the event's type.
However, some user space apps that do the same thing as others may not
have been updated to do auditing and various distributions may or may not
enable the auditing at build time. So, the user space support varies.

-Steve