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

Serge E. Hallyn
2008-11-04T19:28:44Z

Quoting Eric Paris (eparis@redhat.com):
> On Tue, 2008-11-04 at 10:35 -0600, Serge E. Hallyn wrote:
> > Quoting Eric Paris (eparis@redhat.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

Cool, that makes sense.

Would you mind adding a trivial patch to your set commenting
cap_issubset() in capability.h? If you feel it's too outside the scope
of this set I'll send such separately. Every time I see code using
it, it takes me 5 mins to remember which order they're supposed to be
in...

> 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

thanks,
-serge