linux-kernel - Re: [PATCH] syslog: check cap_syslog when dmesg

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Date:	Wed, 8 Dec 2010 16:42:35 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Eric Paris <eparis@...hat.com>
Cc:	"Serge E. Hallyn" <serge@...lyn.com>,
	James Morris <jmorris@...ei.org>,
	Stephen Smalley <sds@...ho.nsa.gov>, dwalsh@...hat.com,
	Kees Cook <kees.cook@...onical.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] syslog: check cap_syslog when dmesg_restrict

Quoting Eric Paris (eparis@...hat.com):
> On Wed, 2010-12-08 at 15:19 +0000, Serge E. Hallyn wrote:
> Doesn't this return -EPERM right now?

Yes.

>   I think the code might be
> incorrect today as well......
> 
> I thought the flow was supposed to be
> 
> if (capable(CAP_SYSLOG))
> 	all good
> else if (capable(CAP_SYS_ADMIN))
> 	WARN, but still good for now

I prefer warn and deny.  Otherwise it's too easy to ignore warnings.  So
I prefer the msg to be there to explain why it failed - not that I expect
it to fail for anyone today.

> else
> 	EPERM
> 
> But it looks to me like the flow is
> 
> if (capable(CAP_SYSLOG))
> 	all good
> else if (capable(CAP_SYS_ADMIN))
> 	WARN, EPERM
> else
> 	EPERM
> 
> >  	}

Yup.

-serge
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