linux-kernel - Re: [PATCH -v2 3/4] AUDIT: collect info when execve results in caps in pE

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Message-Id: <1225825646.4662.22.camel@localhost.localdomain>
Date:	Tue, 04 Nov 2008 14:07:26 -0500
From:	Eric Paris <eparis@...hat.com>
To:	"Serge E. Hallyn" <serue@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-audit@...hat.com,
	sgrubb@...hat.com, morgan@...nel.org, viro@...IV.linux.org.uk
Subject: Re: [PATCH -v2 3/4] AUDIT: collect info when execve results in
 caps in pE

On Tue, 2008-11-04 at 10:35 -0600, Serge E. Hallyn wrote:
> Quoting Eric Paris (eparis@...hat.com):
> > diff --git a/security/commoncap.c b/security/commoncap.c
> > index 8bb95ed..534abb5 100644
> > --- a/security/commoncap.c
> > +++ b/security/commoncap.c
> > @@ -8,6 +8,7 @@
> >   */
> > 
> >  #include <linux/capability.h>
> > +#include <linux/audit.h>
> >  #include <linux/module.h>
> >  #include <linux/init.h>
> >  #include <linux/kernel.h>
> > @@ -373,6 +374,9 @@ int cap_bprm_set_security (struct linux_binprm *bprm)
> > 
> >  void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
> >  {
> > +	kernel_cap_t pP = current->cap_permitted;
> > +	kernel_cap_t pE = current->cap_effective;
> > +
> >  	if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
> >  	    !cap_issubset(bprm->cap_post_exec_permitted,
> >  			  current->cap_permitted)) {
> > @@ -407,6 +411,12 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
> >  	}
> > 
> >  	/* AUD: Audit candidate if current->cap_effective is set */
> > +	if (!cap_isclear(current->cap_effective)) {
> > +		if (!cap_issubset(current->cap_effective, CAP_FULL_SET) ||
> 
> Hi Eric,
> 
> can you explain what the cap_issubset() check is for here?

I'm glad you noticed it, because it is backwards!

should be

if (!cap_issubset(CAP_FULL_SET, current->cap_effective) ||

The idea is that I don't care to audit
1) full set &&
2) this is root &&
3) root should have a full set

This would still consider a root without a full set because the bset had
been changed to be an interesting event.  I'm fine with that.

I'll send -v3 once I hear comments on everything else....

-Eric

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